LIBRARY G

THE

CYCLOPAEDIA

OP

ANATOMY AND PHYSIOLOGY

VOL. I. A— -DEA

1835-1836

THE

CYCLOPAEDIA

OF

ANATOMY AND PHYSIOLOGY.

EDITED BY

ROBERT B. TODD, M.D. F.R.S.

\\

FELLOW OF THE ROYAL COLLEGE OF PHYSICIANS;

PHYSICIAN TO KING'S COLLEGE HOSPITAL ; AND FORMERLY

PROFESSOR OF PHYSIOLOGY AND OF GENERAL AND MORBID ANATOMY IN KING'S COLLEGE,

LONDON, ETC. ETC.

VOL. I. A DBA

1835—1836

LONDON LONGMAN, BROWN, GREEN, LONGMANS, & ROBERTS.

QL7

PREFACE.

To collect a series of Essays on all the various subjects of Anatomy and Phy- siology, by the co-operation of several Authors, who, as far as possible, should be selected in consequence of their special attention to, or interest in, the subject-matter of the articles which each would undertake to furnish, was the object of the Editor in projecting the "Cyclopaedia of Anatomy and Physiology."

The successful inauguration of a similar work on Practical Medicine, which had advanced some way prior to the commencement of this Cyclopedia, afforded great encouragement to the Publishers and to the Editor to prosecute their design.

The first part was published in 1835, twenty-four years ago. It was then calculated that twenty parts would complete the book, arid that not many years would have been sufficient for that purpose,

A glance at the Table of classified Contents will show the multipli- city of topics on which it was proposed to treat: — Anatomy, both as it regards man and all the tribes of inferior creatures, — Anatomy de- scriptive,— Anatomy physiological or histological, — Comparative Anatomy, — Morbid Anatomy, general and special. To these were to be added: Physiology (human and comparative) ; some brief notice of Vegetable Physi- ology ; the Anatomy and Physiology of the different classes of Animals, in- volving, in many instances, much reference to their Zoology ; and lastly Animal Chemistry, including the physiology of the fluids and secretions. VOL. i. a

PREFACE.

Numerous as were the articles which, according to the first plan of the work, were to have been introduced, it was soon found indispensable not only to add others quite new, but also to enlarge considerably the space allotted to each of those which formed the original catalogue, and to multiply greatly the number of illustrations.

All this was rendered necessary by the rapid strides which our know- ledge of many subjects in Anatomy and Physiology began to take at the time when the earlier parts of the Cyclopasdia made their appearance. Perhaps there never was greater activity of research in any branch of science during a given period, than that under which the sciences of Anatomy and Phy- siology advanced during the last quarter of a century. Minute anatomy, which thirty years ago was crude and undigested, now takes very high rank among the various branches of Natural Knowledge. During these years every tissue has been scrutinised ; many obscure points have been cleared up ; much that was wholly unknown has been brought to light. The additions to our knowledge of Anatomy, although there is yet ample room for fresh dis- coveries, have given a totally new phase to Physiology. From being little more than a series of vague and ill-founded hypotheses, scarcely deserving even that name, it has become a well-arranged science, embracing a vast amount of clearly defined facts, which, at once, form a solid basis for a superstructure of sound theory, and throw much light upon the various processes of animal and vegetable life.

It was the constant aim of the Editor, where it was possible, to secure the assistance of Contributors who would be likely to make original investiga- tions, and to employ new researches for furnishing the materiel of their articles. Whilst it is thankfully acknowledged, that in many instances the Editor's most sanguine hopes were fully attained, it is not less true that he was sometimes disappointed, and that much delay of publication and apparent breach of faith took place. A few completely failed to fulfil their engagements, without any assignable reason; others were unavoidably prevented from so doing. In several instances the articles were not completed at the stipulated time. For some of these the Editor was content to wait, notwithstanding that by so doing the immediate sale of the book was injured, and the Editor himself exposed (with apparent justice) to charges of violation of promises. But, in the particular cases referred to, the Editor knew that delay in the comple-

PREFACE.

tion of the articles was caused by an earnest wish on the part of the Authors to do ample justice to their subjects, and a praiseworthy scrupulousness in recording facts which they had not verified by actual observation.

To this it must be added, that for a considerable period the continuance of the work was jeopardised, and its publication wholly suspended for two years, by the death, in rapid succession, of the leading partners of the publishing firm under whose auspices the work was conducted, prior to its passing into ihe hands of its present publishers, the Messrs. Longman.

Nor will the Editor attempt to shield himself from blame as regards the tardy completion of the Cyclopaedia. He is quite ready to confess that, in other hands than his own, it would have been long since finished. He is con- scious that he has been often dilatory, sometimes vacillating, occasionally appalled by the magnitude of the undertaking, and by the knowledge of the inadequacy of his powers to carry it on to a close. At the same time, in self-defence, he feels bound to plead that, soon after the publication of the first two or three parts of the work, certain onerous duties devolved upon him, which greatly curtailed the amount of leisure available for literary pursuits. In the first place, he was called upon, at short notice, to deliver a lengthened course of Lectures on Anatomy and Physiology of a kind quite new in this country, both as regards extent and nature, which demanded a large amount of study and of personal inquiry and investigation ; soon afterwards was added the responsible office of a Hospital Physician and a Teacher of Clinical Medicine; these were, at no long interval, followed by professional engagements, which, although not more responsible, created more urgent and imperative claims upon his time and attention. With all these demands upon him, it will not excite surprise that literary work often became abandoned or postponed.

At length, " per varios casus et tot discrimina rerum," the period of com- pletion has arrived. And the Editor, while he is impressed with a deep sense of gratitude that his own health and life have been spared till the completion of the book, acknowledges, with thankfulness and pride, the invaluable aid which he has obtained from all quarters. He looks back with much of the same feelings which fill the mind of an architect who has projected a large

a 2

PREFACE.

building requiring for its completion a long series of years. While the original design, as well in its defects as in its merits, is due to himself, he is conscious how little he has had to do in supplying the materials, and completing the details of the building. For these he has trusted, and not in vain, to a body of collaborateurs, among whom he is proud to reckon many of the first scien- tific men both in this country and in Europe. How efficiently this work has been done, it is not for the Editor to say, but he deems himself justified in affirming that, for years to come, this Cyclopaedia will furnish a well-stocked field for reference to the student of Anatomy and Physiology.

It is remarkable how few of the members of this little phalanx of contributors have failed to see the completion of the work ! Nevertheless, we have to deplore some serious losses ; and the Editor trusts he may be pardoned for offering a passing tribute to the memory of some of the more distinguished among them.

Foremost among these, although but recently removed from amongst us, was the late Dr. MARSHALL HALL, who furnished articles on the (to him) favourite subjects, HYBERNATION, IRRITABILITY. x Although a veteran in science, he had finished his career before he had reached the ordinary limits of human life. To large gifts of natural genius he added an indomitable industry and perse- verance. His name must always occupy a prominent position in the annals of Physiology, by reason of the active and highly successful part which he took in advancing our knowledge of the Physiology of the Nervous System, and in promoting its application to the investigation of Pathology and the diagnosis and treatment of disease ; and the extremely ingenious speculations and hypotheses which he, from time to time, suggested for the explanation of various natural and morbid phenomena. The manner in which his almost latest hours were employed in applying physiological knowledge to the treatment of asphyxia shows how little it could have been said of him, " Superfluous lags the veteran on the stage."

Still more recently, another veteran, especially distinguished in anatomical science, has fallen while actually in the ranks. Professor HARRISON, having been during the previous day engaged in the duties of his chair, rapidly suc- cumbed, in the course of a night, under an apoplectic seizure. For forty years and upwards he maintained the highest reputation as a Teacher. At

PREFACE.

a time of life long subsequent to that at which most men seek repose from such labour, he was as fresh, clear, full, and impressive, in teaching ana- tomy, at once the most elementary and the most important of the studies accessory to medicine, as in his early days.

The celebrated discoverer of Endosmose, H. DUTROCIIET, lived to the ripe age of seventy-one. The article on that subject in this work was the contribution of his own pen. It contains a summary of his views up to the time of its publication. Dutrochet's discovery has the most interesting and important bearing upon the application of physical laws to the illustration of various processes of living organisms. It gave the clue to the elucidation of many obscure points in the physiology of animals and plants, and took a lead in directing the minds of Physiologists away from abstract and fruitless speculations concerning the nature of Life, into the true path of inquiry as to the dependence of vital phenomena on chemical and physical laws.

The value of this discovery is enhanced by the recent researches of Mr. GRAHAM, which have developed the laws of Osmose (to use his more concise and comprehensive designation), and have shown the intimate con- nexion of osmotic with chemical action. Further experiments on the osmotic phenomena of living animals and plants, assisted by the additional light ob- tained from Mr. Graham's researches, can scarcely fail to lead to important, practical results, both in Physiology and Pathology.

The loss of NEWPORT was a heavy blow to Physiology. A man of his skill as a dissector and observer of that large and most interesting tribe, the Insects, could ill be spared. The combination of such manual dexterity and of so much acuteness of observation as Newport displayed is rarely met with. His investigations embraced at once the most delicate anatomical analyses and the deepest questions of physiology. The article INSECTA, contributed by him to this work, is perhaps the most comprehensive account extant of the anatomy and physiology of this class of invertebrate animals. Newport was cut down in the prime of life, when, after many struggles and difficulties his merits were becoming recognised, and the value of his researches appre- ciated. There can be no doubt, had health and life been given him, he would have largely extended our knowledge of this branch of Comparative Anatomy and Physiology.

PREFACE.

Of not less promise, in a still wider field of research, was JOHN REID, who for a few years before his early removal under a painful and tedious disease, filled the chair of Medicine at the University of St. Andrew's, a position in which his great powers had but a limited scope. Reid was one of those men who are content to take nothing for granted which it was at all in their power to examine for themselves. His admirable investigation of the Anatomy and Physiology of the Eighth Pair of Nerves is a model of anatomical and physiological research, scarcely equalled and not surpassed by any similar essay of recent or remoter times. His articles, HEART and RESPIRATION, in this Cyclopaedia, bear ample testimony to his scientific character, and well sustain the high reputation he had acquired even at a very early age.

The late venerable Dr. BOSTOCK, who died at an advanced age, belonged to a different school of Physiologists from those already referred to. No man was more remarkable for the patience and depth of his literary researches. Conscientious almost to a fault, he has left a scrupulously faithful record of all that was done in Physiology up to the time at which he wrote, affording to those who take an interest in that branch of inquiry an impartial historical review of the progress of science. From the great erudition and sound judgment of this excellent man, the Editor derived many valuable hints in the first stages of the Cyclopedia, in the plan and early progress of which he was pleased to take a lively interest.

Born a British subject, the late W. F. EDWARDS (also a veteran in science although he had by no means attained a great age) had spent most of his life in France and followed his Physiological pursuits there. His principal re- searches were directed to the observation of the influence of various physical agents upon the phenomena of Life, and the investigation of the chemical changes which occur in some of the most important and recondite vital pro- cesses. Many of his Essays, which were at first published as detached Papers, were afterwards collected, and formed his well-known work on the " Influence of Physical Agents upon Life."* Dr. Edwards's researches, whilst they determined many new and highly interesting facts, were especially valu- able as promoting more philosophical views of life than those which referred all vital phenomena to the influence of a hypothetical entity.

* Translated into English by Drs, Hodgkin and Fisher, an. 1832.

PREFACE

An important article on Animal Chemistry in this Cyclopedia (PROTEINE) was contributed by a young and rising chemist, JOHN E. BOWMAN, whose brief career sufficed to impress his friends with a strong sense of the serious loss which society and science experienced by his early removal. His acute and well-cultivated intellect would have done much for chemistry had his life been prolonged, or had he even enjoyed, during its short span, an ordinary amount of health. But his last few years were greatly marred in their use- fulness by a singular chronic malady, which slowly undermined his vital powers, and greatly limited his ability for active exertion, whether bodily or mental. Nevertheless, he has left two works which, although of small size, are of considerable practical utility to the chemical student ; the one devoted to practical chemistry, the other to chemistry in its application to practical medicine.

The Editor takes this opportunity of acknowledging his obligations to gentlemen who, at different periods, rendered him the most efficient assistance in superintending the passing of the work through the press, and in other matters connected with his province.

Dr. ROBERT WILLIS, formerly of London, now extensively engaged in medical practice at Barnes in Surrey, for many years took an active part in the superintendence of the printing of the work, and contributed largely to the Bibliography appended to most of the articles, as he was so well qualified to do by his extensive knowledge of books. Dr. Willis also con- tributed the article ANIMAL. Upon his retirement, the Editor derived similar valuable assistance from his friend and former pupil, Mr. S. ROOD PITTARD, who also contributed several articles. And, subsequently, Dr, HYDE SALTER, now well-known, and of deservedly high reputation as a Physiologist and Physician, kindly afforded his aid in the same way, as well as by his valuable contributions of the articles PANCREAS and TONGUE.

This seems the fitting place to state that it has been found necessary, in a few instances, to depart from the strict alphabetical arrangement, either by placing articles under names not commonly used, or by clubbing together two or more subjects, to which it would appear, at first, more natural to have de- voted separate articles. The necessity for such modifications arose out of

PREFACE.

contingencies to which all works are liable, when they are published in Parts, and dependent for regularity of publication on the punctual contribution of the various articles. Where such punctuality could not be obtained, and where it was found absolutely necessary to curtail delay, the changes above alluded to were adopted as a matter of necessity rather than of choice. Thus, Ear is referred to HEARING, ORGAN OF; Kidney to REN. The union of certain articles together under one heading was sometimes found both convenient for treating the subjects, and economical of space. Thus, the Anatomy of the Brain was conveniently associated with that of the Spinal Cord, and will be found under NERVOUS CENTRES ; that of the Intestinal Canal under STOMACH AND INTESTINAL CANAL (Dr. Brinton) ; and that of the Ovary in the elaborate article of Dr. Farre, UTERUS AND ITS APPENDAGES. SEROUS AND SYNOVIAL MEMBRANES have been treated of under one heading, from the close analogy of their structure ; and Hairs, Nails, Skin, &c., are described under the general title TEGUMENTARY ORGANS.

It was found absolutely necessary, owing to difficulties which otherwise must have completely prevented the completion of the work, to place several articles in a supplementary volume, regardless of strict alphabetical arrange- ment. But it is hoped that for this, as well as the other departures from the strict Encyclopaedic form, compensation will be found in the various Indices, and in the Table of Classified Contents.

26 Brook Street, Grosvenor Square, London, Jan. 1859.

CLASSIFIED CONTENTS

THE CYCLOPEDIA OF ANATOMY AND PHYSIOLOGY.

HUMAN ANATOMY, DESCKIPTIVE.

Abdomen Dr. Todd

Ankle-joint Dr. Brenan

Aorta Dr. Hart

Vol. Page i. 1

i. 151 i. 187

Arm, Muscles of' the

Dr. Hart i. 219

Articulation ......... Dr. Todd ............

Axillary Artery ... Dr. Hart ............

Azygos ............... Dr. Harrison ......

Bladder ............... Dr. Harrison ......

Brachial Artery ... Dr. Hart ............

Brain. See Nervous Centres.

Carotid Artery ...... Dr. Hart ............

Cranium ............ J. Malyn, Esq. ...

Diaphragm ......... Dr. Benson .........

Ear. See Hearing, Organ of.

Eighth Pair of Nerves. See Glosso-

pharyngeal ; Par Vagum ; Spinal

Accessory. Elbow-joint ......... Dr. Hart ............

Extremity ......... Dr. Todd .........

Eye .................. Dr. Jacob .........

Femoral Artery ... Dr. Alcock .........

Fibular Artery ...... Dr. Todd .........

Fifth Pair of Nerves Dr. Alcock .........

Foetus ............... Dr. Montgomery...

Foot, Bones and1) _

lf Dr. Todd .........

Joints of the J

Fourth Pair ofi

} Dr. Alcock .........

Nerves J

Generation, Or- -^ T. Rymer Jones, -\ gans of J Esq. J

Glosso-pharyngeal

,T Nerve

„

Dr. Reid

Hand, Bones and

Joints of the VOL. i.

Dr. Todd.

i. 246

i. 363

i. 364

i. 376

i. 465

i. 482

i. 724

ii. 1

ii. 65

ii. 154

ii. 171

ii. 235

ii. 267

ii. 268

ii. 316

ii. 338

ii. 370

ii. 406

ii. 494

ii. 505

Hand, Muscles of "i Bishop MacDou-

the J gall

Hearing, Organ of T. W. Jones, Esq.

Heart Dr. Reid

Heart, Arrange- -»

ment of the Fi- \H. Searle, Esq. ...

bres of the J

Hip-joint H. Hancock, Esq.

Iliac Arteries Dr. Alcock

Innominata Arteria H. Hancock, Esq. Kidney. See Ren.

Knee-joint A. Higginson, Esq.

Lachrymal Organs T. W. Jones, Esq.

Larynx J. Bishop, Esq. ...

Leg, Muscles of. A.T.S. Dodd, Esq.

Liver E. Wilson, Esq. ...

Mammary Glands S. Solly, Esq

Mucous Membrane W. Bowman, Esq.

Nervous Centres ... Dr. Todd

Ninth Pair of-|

Nerve, }*•****..-

Nose J. Paget, Esq

(Esophagus Dr. G. Johnson ...

Optic Nerves Dr. Mayne

Orbit Dr. G. Johnson ...

Pacinian Bodies ... W. Bowman, Esq.

Pancreas Dr. Hyde Salter ...

Par Vagum Dr. J. Reid

Pelvis John Wood, Esq.

Penis E. Wilson, Esq. ...

Perineum Dr. Mayne

Peritoneum S. R. Pittard, Esq.

Pharynx W. Trew, Esq. ...

Pleura S. R. Pittard, Esq.

Prostate J. Adams, Esq. ...

Vol. Page

[ ii. 519

ii. 529

ii. 577

ii. 619

ii. 776

ii. 827

ii. 850

iii. 44

iii. 78

iii. 100

iii. 137

iii. 160

iii. 245

iii. 484

iii. 712

iii. 721

iii. 723

iii. 758

iii. 762

iii. 782

iii. 876

*. 81

iii. 881

s. 114

iii. 909

iii. 919

iii. 935

iii. 945

iv. 1

iv. 146

CLASSIFIED CONTENTS.

••. Thos. Williams s. 258

Vol. Page Radial Artery Dr. Brinton iv. 221

Radio-ulnar Arti-T _

\Dr. Brinton iv. 228

culation J

Ren Dr. Johnson iv. 231

Respiration, Or- gans of

Salivary Glands ... N. Ward, Esq. ... iv. 422 Scrotum Dr. Brinton iv. 438

Serous and Syno-1 ^

^ J \Dr. Brinton iv. 511

vial Membranes J

Sesamoid Bones ... S. R. Pittard, Esq. iv. 541 Seventh Pair °^T n 7? • / Nerves J

Shoulder-joint Dr. M( Dowel iv. 571

Sixth Pair of Nerves Dr. Brinton iv. 621

Spinal Accessory^

> Dr. John Reid iv. 745

Nerve J

Spinal Nerves N. Ward, Esq. ... iv. 750

Spleen Professor Kolliker i v. 771

Stomach and In- testinal Canal

\Dr.Bri

Brinton s. 293

Subclavian Arteries Dr. MlDowel

Supra-renal Cap-~i _

\ Prof. Heinrich Frey sules J

Sympathetic Nerve Dr. Drummond ...

Temporo-Maxil- -»

lary Articula- I S. R. Pittard, Esq. tions J

Testicle T. B. Curling, Esq.

Thorax Dr. Hutchinson ...

Thymus Gland Dr. Handheld Jones

Thyroid Gland ... Dr.Handfield Jones

Tibio-fibular Ar- ticulations

Tongue Dr. Hyde Salter ...

Urethra John Adams, Esq.

Uterus and its Ap- 1 _

" \ Dr. Arthur Farre pendages J

Venous System . . . Dr. M' Dowel

Vesicula Prostatica Prof. Leuckhardt Vesiculse Seminales S. R. Pittard, Esq. Wrist-joint Dr. M' Dowel

Dr. M'Dowel

Vol. Page iv. 814

iv. 827 s. 423

iv. 937

iv. 976 iv. 1016 iv. 1087 iv. 1102

iv. 1118

iv. 1120 iv. 1244

s. 545

iv. 1403 iv. 1415 iv. 1429 iv. 1505

HUMAN ANATOMY, SURGICAL OR TOPOGRAPHICAL.

147 Fore-arm, Muscles,

173 and Regions of /

216 Gluteeal Region ... A. T. S. Dodd,Esq. ii.

358 Groin, Region of the Dr. Todd ii.

367 Hand. Regions ofl _ ,. _. „ .. [• Bishop Mac Dougall u.

746 Leg, Regions of the A. T. S. Dodd, Esq. iii.

Neck, Muscles and i _

}J. Simon, Esq. ... in. 62 Regions of the J

207 Parotid Region ... Dr. G.Johnson... iii. Popliteal Region ... W. Trew, Esq. ... iv. Scapular Region ... Dr. M' Dowel iv.

Ankle, Region of the Dr. Brenan i.

Anus R. Harrison, Esq. i.

Arm Dr. Hart i.

Axilla Dr. Benson i.

Back Dr. Benson i.

Cranium, Regions -j

and Muscles oflz>r. Todd i.

the

Elbow, Region of the Dr. Hart. ii.

Face R. Partridge, Esq. ii.

Foot, Regions arid

Muscles of

\A.T.S.Dodd,Esq. ii. 350

361

500 503

523

126 561

902 60 433

ANATOMY, GENERAL OR PHYSIOLOGICAL.

Adipose Tissue Dr. Craigie i. 56

Artery Dr. Hart i. 220

Bone Dr. Benson i. 430

Bursas Mucosae Dr. Brenan i. 467

Cartilage Dr. Benson i. 495

Cavity Dr. Todd i. 500

Cellular Tissue R.D.Grainger,Esq. i. 509

Cilia Dr. Sharpey i. 606

Erectile Tissue Dr. Hart ii. 144

Excretion Dr. Alison ii. 147

Fascia Dr. Todd ii. 229

Fibro-cartilage. Dr. Todd ii. 260

Fibrous Tissue ... R.D. Grainger, Esq. ii. 263'

Ganglion R.D.Grainger,Esq. ii. 371

Gland R.D. Grainger,Esq. ii. 480

Lymphatic S. Lane, Esq iii. 205

Membrane Dr. Todd iii. 331

Meninges Dr. Todd iii. 331

Muscle W. Bowman, Esq. iii. 506

Nerve Dr. Todd iii. 591

Nervous System ... Dr. Todd iii. 585

Osseous Tissue ... J. Tomes, Esq. ... iii. 847

Skeleton Jos. Maclise, Esq. iv. 622

Vein 5. J. A. Salter, Ef<q. iv. 1367

CLASSIFIED CONTENTS.

ANATOMY, ABNORMAL AND MORBID.

Vol. Page

Adhesion B. Phillips, Esq.... i. 49

Ankle-joint It. Adams, Esq. ... i. 154

Artery W. H. Porter, Esq. i. 226

Bladder B. Phillips, Esq.... i. 389

Blood Dr. Babinyton ... i. 415

Bone W. H. Porter, Esq. i. 438

Cicatrix A.T.S.Dodd,Esq. i. 602

Cirronosis Dr. Todd i. 694

Cyst R. Phillips, Esq.... i. 787

Elbow-joint R. Adams, Esq. ... ii. 67

Foot A.T.S.Dodd,Esq. ii. 347

Hand R. Adams, Esq. ... ii. 510

Heart Dr. Todd ii. 630

Hermaphroditism... Dr. Simpson ii. 684

Hernia W. H. Porter, Esq. ii. 738

Hip-joint JR. Adams, Esq. ... ii. 780

Hypcrrcmia and "I Anaemia J

Hypertrophy and Atrophy ,

Knee-joint JR. Adams, Esq. ... iii.

Larynx W. H. Porter, Esq. iii.

Lymphatic System Dr. Todd iii.

Nervous Centres ... Dr. Todd iii.

Products, Adven- titious

Vol. Pago

Dr. Todd..., . ii. 825

Dr. Todd . . ii. 826

48 114 232 712

I Dr. Wolshe iv. 71

Shoulder-joint R. Adams, Esq. ... iv. 577

Softening and In-") _

\ Dr. P. M. Duncan iv. 703 duration J

Teratology Professor Vrolik ... iv. 942

Wrist-joint R. Adams, Esq. ... iv. 1508

ANATOMY, COMPARATIVE.

Chyliferous System Dr. Grant i.

Digestive Canal ... Dr. Grant ii.

Lymphatic and l

> S. Lane, Esq. Lacteal System J

Muscular System... Prof. It. Jones ... iii. Nervous System ... J. Anderson, Esq. iii.

600 27

iii. 205

530 601

Osseous System ... Prof. R. Jones

Shell Dr. Carpenter...

Teeth Professor Owen

Tegumentary Or- "1

gans (Hair, Nails, I T. Huxley, Esq.

Feathers, &c.) J

in. iv.

iv.

820 556 864

*. 473

ZOOLOGICAL ANATOMY AND PHYSIOLOGY.

Acalephse Dr. Coldstream

Acrita jR. Owen, Esq.

Amphibia T. Bell, Esq

Animal Kingdom Professor Grant

Annelida Dr. Milne Edwards

Arachnida Dr. Audouin

Articulata Professor Owen

Aves R. Owen, Esq.

Carnivora T. Bell, Esq.

Cephalopoda JR. Owen, Esq,

Cetacea M. F. Cuvier

Cheiroptera T. Bell, Esq.

Cirrhopoda Dr. Coldstream

Conchifera M. Deshayes

Crustacea Dr. Milne Edwards

Echinodermata Dr. Sharpey

Edentata T. Bell, Esq.

Entozoa Professor Owen

Gasteropoda T. R. J

Insecta G. Newport, Esq.

n ... i.	35
. ... i.	47
i.	90
nt i.	107
>ards i.	164
i.	198
n ... i.	244
. ... i.	265
i.	470
. ... i.	517
i.	562
i.	594
IM ... i.	683
i.	694
wards i.	750
ii.	30
ii.	46
°n ... ii.	111
Esq. ii.	377
Esq. ii.	853

Insectivora T. Bell, Esq ii. 994

Mammalia Professor Owen ... iii. 234

Marsupialia Professor Owen ... iii. 257

Mollusca Professor Owen ... iii. 363

Monotremata Professor Owen ... iii. 366

Myriapoda Prof. R. Jones ... iii. 545

Pachydermata Prof. JR. Jones ...iii. 858

Pisces Prof. R. Jones ...iii. 955

Polygastria Prof. R. Jones ... iv. 2

Polypifera Prof. R. Jones ... iv. 18

Porifera Prof. R. Jones ... iv. 64

Pteropoda Prof. R. Jones ... iv. 170

Quadrumana Professor Vrolik iv. 194

Eeptilia Prof . R. Jones ... iv. 264

Rodentia Prof. R. Jones iv. 368

Rotifera Dr. Lankester iv. 396

rDr. T. Spencer -|

Ruminantia <^ } *. 506

I Cobbold J

Solipeda Prof. R. Jones ... iv. 713

Tunicata Prof. R. Jones iv. 1185

CLASSIFIED CONTENTS.

PHYSIOLOGY.

Absorption ...	Dr Bostock	Vol. i	Page 20
	Dr. Symonds	i.	64
Albino ...	Dr. Bostock	i.	83
	Dr. Willis	i	118
		i.	257
	Dr. Allen Thomson	i.	638
Contractility	Dr. Alison .........	i	716
	Dr. Symonds	i.	791
	Dr. Bostock	ii.	6
Elasticity	Dr Brenan ,	ii	55
Electricity, Animal Endosmosis	Dr. Coldstream ... Dr. Dutrochet ...	ii. ii	81 98
	Dr. Allen Thomson	ii.	424
Hearing Heat Animal ...	Dr. Todd Dr W F Edwards	ii. ii	564 648
	Dr. Marshall Hall	ii.	764
		iii.	1
	Dr. Marshall Hall	iii.	29
Life	Dr. Carpenter	iii.	141
Luminousness, T Animal J Motion, Animal, -» including Loco- i- motion J	Dr. Coldstream ... J. Bishop, Esq. ...	iii. iii.	197 407

Dr. J. B.

derson

San-

Muscular Motion... W. Bowman, Esq. Nervous System ... Dr. Todd ............

Nutrition ............ Dr. Carpenter ......

Ovum ............... Dr. Allen Thomson

Parturition ......... Dr. Rigby .........

Pulse .................. Dr. Guy ............

Reproduction. Ve-

' getable (Vege- I

table Ovum) J Respiration ......... Dr. John Eeid ...

Secretion ............ Dr. Carpenter ......

Sensation ............ Dr. Todd ............

Sensibility ............ Dr. Todd ............

Sleep .................. Dr. Carpenter ......

Smell ............... Dr. Carpenter ......

Symmetry ..... . ...... S. R. Pittard, Esq.

Sympathy ............ Dr. Todd ............

Taste .................. Dr. Carpenter ......

Temperament ...... Dr. Todd .........

Touch ............... Dr. Carpenter .....

Varieties of Man-

Vol. Page iii. 519

iii. 720o.

iii. 741

s. 1

iii. 904 iv. 181

s. 211

iv. 325

iv. 439

iv. 508

iv. 510

iv. 677

iv. 697

iv. 845

iv. 852

iv. 856

iv. 935

iv. 1163

kind

Dr. Carpenter iv. 1294

Vision W.W. Cooper, Esq. iv. 1436

Voice John Bishop, Esq. iv. 1475

ANIMAL CHEMISTRY, PHYSIOLOGY OF THE FLUIDS AND

SECRETIONS.

Acids, Animal	W.T. Brande, Esq. i. W. T. Brande, Esq. i.	47 55	Milk Mucus	.. Dr. G. O. Rees ... iii. .. Dr. G. O. Rees ... iii	358 481
Albumen	W. T. Brande, Esq. i	88	Organic Analysis.	.. Dr. Miller ... iii.	792
Blood		404	Protein	. . Prof. J E. Bowman iv	162
Bile	W. T. Brande, Esq. i.	374	Saliva	.. Dr. Owen Rees .. iv.	415
	W.T. Brande, Esq. i.	562		f Drs. Wagner and ~) .
Fat	W.T. Brande, Esq. ii.	231		1 Leuckhardt J	472
	W. T. Brande Esq ii	257	Sweat	.. Dr. G. O. Rees ... iv.	841
Gelatin	W. T. Brande, Esq. ii	404	Synovia	.. Dr. G. O. Rees ... iv.	856
Haematosine	Dr. G. O. Rees... ii.	503	Urine	.. Dr. G. O. Rees ... iv.	1268

GENERAL SUBJECTS.

Medical Statistics .... Dr. Guy iv. 801 | Microscope Dr. Carpenter iii. 331

i Vital Statistics Dr. Guy iv. 1469

CONTENTS OF THE FIRST VOLUME.

Abdomen.	Dr. Todd Dr. Bostock ....	Page 1 20	Bladder, Normal Ana- )	Page Dr. Harrison .... 376
	Dr. Coldstream . .	35	Bladder, Abnormal ^
Acids Animal	W T.Brande Esq	47		B. Phillips, Esq. . 388
Acrita	R Owen ESQ	47	Blood	Dr. Milne Edwards 404
	B. Phillips, Esq .	49	Blood, Morbid Condi- )
	W T Brande Esq	55		Dr. Babington .. 415
Adipose Tissue ......	Dr. Craiffie .	56	Bone NormalAnatomy	Dr Benson,.. . .. 430
A°-e .,	Dr. Siiwonds ....	64	Bone, Pathological )
	Dr. Bostock	83		W.H. Porter, Esq. 438
Albumen	W. T. Brande Esq	88	Brachial Artery ....	Dr. Hart 465
Amphibia	T Bell Esq ....	90
Animal Kingdom < • . .	Dr. Grant	107	Carnivora	T. Bell, Esq 470
Animal . •	Dr. Willis	118		Dr. Hart 482
Ankle Region of the. .		147		Dr. Benson 495
Ankle, Joint of the . .		151	Cavity	Dr. Todd 600
Ankle-joint,Abnormal ) Condition of the . . *	R. Adams, Esq. . .	154	Cellular Tissue	R.D.Grainger,Esq. 509 R. Owen Esq .. 517
Annelida .	Dr Milne Edwards	164		W T Brande Eiq 562
	R. Harrison Esq	178		Mons. F. Cuvier . . 562
Aorta	Dr. Hart Dr. Audoitin. ....	Ib7 198	Cheiroptera Chyliferous System . .	T. Bell, Esq 594 Dr Grant 600
Arm	Dr. Hart	216		A. T. S.Dodd Esq. 602
Arm Muscles of the .	Dr Hart..	219	Cilia	Dr. Sharpey .... 606
Artery	Dr. Hart	220		Dr. Allen Thomson 638
Artery, Pathological >				Dr. Coldstream . . 683
Conditions of . . . . ' Articulate	W.n. Porter, Esq. R. Owen, Esq. . .	226 244	Cirronosis	Dr. Todd 694 M. Deshayes .... 694
Articulation	Dr. Todd	246	Contractility	Dr. Alison 716
		257		J. Malyn Esq. . . 724
Aves	R. Owen, Esq. . .	265	Cranium, Regions and }	Dr. Todd 746
Axilla		358	Muscles of the. . . . *
Axillary Artery ......	Dr. Hart	363		Dr. Milne Edwards 750
	Dr Harrison ....	364	Cvst . .	B. Phillips, Esq. . 787
Back		367	Death	Dr Symonds .... 791
Bile	W.T Brande Esq	374

THE

CYCLOPAEDIA

ANATOMY AND PHYSIOLOGY

a

terms synoi

ABDOMEN, (in anatomy,) with which the terms venter and alvus are sometimes used synonymously. Gr. ya<mj£. Germ, bauch, un- terleib, hinterleib. Ital. ventre, pancia, abdo- mine: the French anatomists use the word abdomen as we do, and also the term ventre as we do belly ; also bas-ventre. It is so called, " quod abdi et tegi soleat, aut quod alimenta in eo abdantur, aut intestina ibi sint abdita"*

The term denotes a particular region and cavity in a large proportion of the animal series, being found in most of the classes from Mam- malia down to Articulata. It is impossible to give such a definition of this region as will apply to all ; it appears, however, to have one property sufficiently general, viz. that it con- tains in all these classes more or less of the digestive organs. Thus, to ascend from the Articulata : —

It is in the class Insecta of the Articulata that we find the most defined region bearing this name. This region is the most posterior of the three portions into which the body of an insect is divided, and is composed of a series of seg- ments which unite to form a cavity enclosing the viscera subservient to nutrition, respiration, and reproduction ; it does not contain any of the organs concerned in locomotion. It is com- posed of a series of simple hoops, united to each other by a ligamentous connexion, which allows the abdomen to be flexible or otherwise, according to the closeness of the union ,f The abdomen is united by its anterior extremity to

* Facciolati, in verb.

t See a very good engraving from Cams, of the segments of an insect, in Roget's Uridgewater Trea- tise, vol. i. p. 321. VOL. i.

the thorax. (See INSECTA.) In the Arachnida there is also a similar division of the body, to which the name of abdomen has been applied, united in front with the cephalo-thorax, and separated from it by a deep groove, which leaves only a slender pedicle between them ; like that of the Insecta it contains the principal viscera. (See ARACHNIDA.)

In all the divisions of the Vertebrata there is an abdomen . In fishes the abdomen is situated towards the posterior extremity of the body, and is separated from the heart in front by a strong membrane analogous to the diaphragm ; it contains the digestive and generative organs. In reptiles the abdomen is that region which lies immediately anterior to the anus ; in many classes it is not separated from the cavity con- taining the lungs, so that the lungs, heart, organs of digestion and generation are all con- tained in one great cavity ; in the crocodile, however, a layer of muscular fibres, having the appearance of a diaphragm, covers the perito- neum,where it is connected with the liver, so that the lungs do not project into the abdomen. In birds, the abdomen extends from the posterior extremity of the sternum to the anus ; it is, as in fishes, separated from the thorax by a mem- brane which, though not muscular, is analogous to the diaphragm, but is perforated so as to allow the air to pass into the abdominal cells. In Mammalia, the abdomen is placed between the pelvis and thorax, with the former of which it is continuous ; but it is separated from the latter by the diaphragm ; its principal contents consist of the digestive organs, and its size varies in reference to their respective degrees of development.

ABDOMEN.

ABDOMEN (in* huritari anatomy.) In ex- amining .the* Jiuiaatt. skeleton, we. notice that from Jlte ajt^Cot'lhertboi^x.to th£ "inferior out- let of the pelvis, there exists one great oblong excavation. The two superior fifths of this cavity are separated from the remaining portion in the entire subject by a musculo- tendinous lamella, which, thrown into a vaulted form, constitutes the partition between the cavity of the thorax above and that of the abdomen below. This latter cavity communicates inferiorly with the space circumscribed by the ossa innominata, denominated the cavity of the pelvis ; nor is there any natural line of demarcation between the two cavities. The communication between the two cavities is as free in the recent subject as it is in the skeleton, and under various con- ditions the contents of those cavities pass from the one to the other. A plane extended hori- zontally from the linea iliopectinea on one side to the corresponding line on the other would constitute an artificial floor to the cavity of the abdomen, properly so called, and a limit be- tween it and the pelvis; and this artificial divi- sion of a cavity, naturally single, may be useful in describing the positions of viscera, but to understand the functions of the abdomen, it will be expedient to consider that cavity and the pelvis as one. Some anatomists ob- ject to the use of the term cavity as applied to the abdomen, because no cavity can be said to exist, except in the skeleton or in the evisce- rated subject; neither can there properly be said to be a cavity of the thorax or of the cra- nium, inasmuch as that cavity is obliterated so long as the viscera are in a state of integrity. I apprehend that the objection is hypercriti- cal, as it must be evident that the cavity does not become apparent till the viscera have been removed; nevertheless, it is perfectly correct to say that it contains the viscera, nor is it in- correct to make use of the expression " anatomy of the abdominal cavity," to imply the anatomy of its contents when in their natural position. Hence, then, we derive a natural subdivision, in treating the subject of this article, into two heads: 1. the anatomy of the walls of the abdomen ; and, 2. the anatomy of the cavity of the abdomen.

I. Of the walls of the abdomen. — One of the most striking differences between the abdomen and the other great visceral cavities consists in the small proportion of bone that exists in its walls. The osseous boundaries of the abdomen may be thus enumerated : superiorly, towards the posterior and outer part, the false ribs; posteriorly, the lumbar region of the spine, which by its transverse processes affords strong points for the attachment of muscles, and by the bodies projects into the cavity, forming an imperfect septum, slightly convex on its anterior surface, and dividing the cavity into two symmetrical portions. Inferiorly, the alse of the ilia afford lateral, expansions, which support some of the contents of the abdo- men, and the pelvic brim completed behind by the promontory of the sacrum, forms the opening by which the cavity of the true pelvis communicates with that of the abdomen.

Between the inferior margin of the thorax and the superior margin of the false pelvis are stretched muscular lamellae and tendinous ap- oneuroses, the cingulum abdominis musculoso- aponeuroticum of Albinus and Haller, which, with integument, cellular membrane, &c. form the anterior, lateral, and for the most part the posterior walls of the abdomen, and circum- scribe that space to which we have already alluded under the name of the cavity of the abdomen.

The superior wall of the abdomen is the diaphragm, and the inferior wall of the abdo- men, strictly so called, is formed by the ilia and their muscles, and is open in the centre at the superior outlet of the pelvis ; but if the abdominal and pelvic cavities be considered as one, then those parts which fill up the inferior outlet of the latter must be considered as likewise constituting the inferior wall of the former.

In the male adult the abdomen presents an expanded convex surface anteriorly (the ante- rior wall or proper abdominal region) ; poste- riorly a broad surface not so extensive, situated between the last ribs and the superior margin of the pelvis, and divided into two by the lumbar portion of the spine (the posterior wall, the loins, or lumbar regions.) The anterior and posterior walls are connected with each other on the sides by two narrow regions (the lateral walls or the flanks.)

The outline of the anterior wall or pro- per abdominal region constitutes an oval, whose long axis is vertical. The surface is generally more or less convex during life, proportionally with the degree of embonpoint of the indivi- dual, and also according to the condition of the diaphragm. After death, excepting in very fat subjects, or where the intestines or peritoneal cavity are much distended from any cause, this surface is in a variable degree collapsed, and more or less concave, but especially so in very thin and emaciated subjects. There is a con- stant adaptation in the condition of this surface to that of the abdominal viscera, so that the practitioner can in general argue pretty accu- rately, from the state of the abdominal surface, respecting that of the abdominal viscera, ex- cept in cases where every thing is masked by a superabundant deposition of adipose substance. So close is the apposition of the abdominal wall to the surfaces of the subjacent viscera, that in some cases of extreme emaciation the peristaltic movement of the intestinal canal is manifested by the successive elevation and depression of small portions of the walls corresponding to the dilated and contracted portions of intestine. This surface is divided into two equal and symmetrical portions by a groove which exists along the middle line, and which is chiefly ap- parent in the two superior thirds. This groove commences below the ensiform cartilage, where there is a slight depression, denominated the scrobiculus cordis, (creux de 1'estomac.) In this line, about midway between the pubis and xiphoid cartilage, is the round depression called the umbilicus or navel. Just over the pubis there is a prominent surface in both sexes covered

ABDOMEN.

with hair ; in the female it is much more pro- minent than in the male, and is called the mons Veneris. In subjects where the muscular sys- tem is well developed, there exists on each side of this median groove an oblong convexity, ex- tending from the anterior surface of the lower part of the chest to the pubis ; these convexities indicate the situation of the recti muscles. In statues representing athletic men, the promi- nences occasioned by these muscles are gene- rally very well shewn, and are divided by trans- verse superficial depressions into smaller qua- drilateral portions, generally three in number. External to these prominences there is, in similar muscular subjects, a fissure extending from the border of the chest, in a slightly curved course with external convexity, to a point a little to the inner side of the anterior superior spine of the ilium ; this fissure has internal to it the prominence from the recti muscles, and external that from the broad muscles of the

abdomen. Gerdy calls it the lateral groove or furrow of the abdomen.* (See Jig. 1.)

The posterior wall or the region of the loins, (lumbar region,) is in every way of less extent than the anterior. Its vertical height is equal to the distance between the last rib and the margin of the ilium. It is continuous on the sides with the flanks, and is divided along the middle line by a groove, corresponding to the lumbar spinous processes, into two symmetrical portions, each of which forms a large and pro- minent relief. Each relief corresponds to a great muscular mass, which almost wholly oc- cupies this region, and its prominence is greatest when those muscles are in a state of contrac- tion, as during the erect posture. Each relief is concave from above downwards, and in a degree directly proportionate to the contrac-

* Gerdy, Anatomic des Formes Exterieures, p. 189. The above engraving is reduced from the folio plates which accompany this \vork.

ABDOMEN.

ABD&MENYin hurtiaii anatomy.) In ex- Between the inferior margin of the thorax

Hence, then, we derive a natural subdivision, in treating the subject of this article, into two heads: 1. the anatomy of the walls of the abdomen; and, 2. the anatomy of the cavity of the abdomen.

I. Of the walls of the abdomen. — One of the most striking differences between the abdomen and the other great visceral cavities consists in the small proportion of bone that exists in its walls. The osseous boundaries of the abdomen may be thus enumerated: superiorly, towards the posterior and outer part, the false ribs ; posteriorly, the lumbar region of the spine, which by its transverse processes affords strong points for the attachment of muscles, and by the bodies projects into the cavity, forming an imperfect septum, slightly convex on its anterior surface, and dividing the cavity into two symmetrical portions. Inferiorly, the alae of the ilia afford lateral, expansions, which support some of the contents of the abdo- men, and the pelvic brim completed behind by the promontory of the sacrum, forms the opening by which the cavity of the true pelvis communicates with that of the abdomen.

stant adaptation in the condition of this surface to that of the abdominal viscera, so that the practitioner can in general argue pretty accu- rately, from the state of the abdominal surface, respecting that of the abdominal viscera, ex- cept in cases where every thing is masked by a superabundant deposition of adipose substance. So close is the apposition of the abdominal wall to the surfaces of the subjacent viscera, that in some cases of extreme emaciation the peristaltic movement of the intestinal canal is manifested by the successive elevation and depression of small portions of the walls corresponding to the dilated and contracted portions of intestine. This surface is divided into two equal and symmetrical portions by a groove which exists along the middle line, and which is chiefly ap- parent in the two superior thirds. This groove commences below the ensiform cartilage, where there is a slight depression, denominated the scrobiculus cordis, (creux de 1'estomac.) In this line, about midway between the pubis and xiphoid cartilage, is the round depression called the umbilicus or navel. Just over the pubis there is a prominent surface in both sexes covered

ABDOMEN.

Eg-. 2.

with liair ; in the female it is much more pro- minent than in the male, and is called the mom Veneris. In subjects where the muscular sys- tem is well developed, there exists on each side of this median groove an oblong convexity, ex- tending from the anterior surface of the lower part of the chest to the pubis ; these convexities indicate the situation of the rectl muscles. In statues representing athletic men, the promi- nences occasioned by these muscles are gene- rally very well shewn, and are divided by trans- verse superficial depressions into smaller qua- drilateral portions, generally three in number. External to these prominences there is, in similar muscular subjects, a fissure extending from the border of the chest, in a slightly curved course with external convexity, to a point a little to the inner side of the anterior superior spine of the ilium ; this fissure has internal to it the prominence from the recti muscles, and external that from the broad muscles of the

abdomen. Gerdy calls it the lateral groove or furrow of the abdomen.* (See Jig. 1.)

The posterior wall or the region of the loins, (lumbar region,) is in every way of less extent than the anterior. Its vertical height is equal to the distance between the last rib and the margin of the ilium. It is continuous on the sides with the flanks, and is divided along the middle line by a groove, corresponding to the lumbar spinous processes, into two symmetrical portions, each of which forms a large and pro- minent relief. Each relief corresponds to a great muscular mass, which almost wholly oc- cupies this region, and its prominence is greatest when those muscles are in a state of contrac- tion, as during the erect posture. Each relief is concave from above downwards, and in a degree directly proportionate to the conlrac-

* Gerdy, Anatomic des Formes Exterieures, p. 189. The above engraving is reduced from the folio platt-s which accompany this work.

ABDOMEN.

tion of the muscles, insomuch that in some in- dividuals the concavity is habitually very con- siderable, as in those who carry burdens on the head or in front of the body, in pregnant wo- men, &c. (See/g. 2.)

The limit of this wall on each side is indicated by a groove or fissure which passes .obliquely upwards and outwards towards the ribs, and corresponds to the outer margin of each relief, or that of the lumbar muscles; these lines also indicate the posterior limits of the lateral walls of the abdomen, or the flanks. Anteriorly the flank of each side is continuous with the anterior wall of the abdo- men ; above it is limited by the margin of the thorax, and below by the margin or crest of the ilium. It is concave on its surface from above downwards, (except in cases of great embon- point, where the concavity is obliterated,) and convex from before backwards. Gerdy remarks that in subjects in which the muscles have a considerable development, a relief is formed just above the crista ilii by the broad muscles of the abdomen at their insertion into this osseous border. Upon antique statues this relief is in general made too prominent.

The anterior or proper abdominal region has been subdivided into smaller compartments, with a view to facilitating descriptions, patho- logical or otherwise. This subdivision is com- pletely arbitrary, and therefore some differences will be found among the various anatomical authors as to the precise limits of each region. That which is here subjoined, however, appears to be pretty generally agreed upon in this country. Lines connecting particular points drawn upon the surface, mark out these subdi- visions, and if planes be supposed to be carried from these lines horizontally backwards to the posterior wall, the cavity of the abdomen will thus be divided into segments, each of which has its particular portion of the abdominal viscera. It is an instructive exercise for the student to practise himself in examining the particular viscera which correspond to particu- lar regions. We are thus enabled, as Blandin has remarked,* to resolve the problem, " a point of the surface of the abdomen being wounded deeply in a given direction, to de- termine what organs have been injured ; and reciprocally, an organ having been wounded in a particular part of the abdominal cavity by a sharp instrument, which entered in a given direction, to determine what part of the abdominal walls must necessarily have been injured. "t

The limits of these several regions or com- partments may be thus indicated : j let a line be drawn horizontally from the extremity of the last rib on one side to the same point on the other, and let another line parallel to the pre- ceding be drawn between the two anterior superior spinous processes of the ilium ; the

* Anatomie Topographique, p. 423.

t The division of the surface of the abdomen into regions is as old as Aristotle.

t See an engraving exhibiting these subdivisions, in the article ABDOMEN of the CYCLOPEDIA OF

PRACTICAL MEDICINE.

abdominal surface is thus divided into three great regions, each of which is subdivided into three by means of a vertical line let fall on each side from the anterior extremity of the seventh or eighth rib to a point a little external to the spine of the pubis. Nine regions are thus marked out, the relations and boundaries of which may be described as follows.

The superior region, or that above the first horizontal line, is the Epigastrium, which name it derives from its close relation to the stomach : (i7r>, upon, over ; yew-rug, the stomach.) The epi- gastrium is bounded superiorly and laterally by the margin of the thorax, and its inferior limit is indicated by the transverse line. The verti- cal lines subdivide it into two lateral regions, each of which is bounded immediately above by the lower margin of the thorax, beneath which these regions extend in a direction up- wards and backwards : they are hence called hypochondria (Wo, under, p^ov^os, cartilage). Between the hypochondria, is the proper epigastric region, which at its superior part and just below the xiphoid cartilage presents the depression already alluded to under the name of scrobiculus cordis (scrobiculus, the diminutive of scrobs, a depression).

Immediately below the epigastrium, and separated from it by the superior horizontal line, is the umbilical region, which has its name from the presence of the umbilicus in it. This region is limited above and below by the two horizontal lines, and is subdivided by the intersection of the two vertical lines into three regions : the lateral ones are the lumbar regions, so called from their correspondence with those portions of the posterior abdominal wall which bear the same name ; and the middle one is the proper umbilical region.

Between the inferior horizontal line and the margin of the pelvis, is the hypogastrium, (VTTO, beneath, yacrT*!^, the stomach). This region is li- mited below in the centre by the pubis, and on each side it communicates with the upper part of the thigh. It is subdivided into the iliac regions on each side, and the proper hypo- gastric or pubic region in the centre. The two former constitute the upper or abdominal portion of the great region of the groin, which is completed inferiorly by the upper part of the anterior surface of the thigh. These regions afford peculiar interest to the surgical ana- tomist, in consequence of the occurrence in them ofkthe most common forms of hernia.* (See GROIN, REGION OF THE.)

The structures which enter into the com- position of the abdominal parietes, or their elements, (as the term has been lately applied,) are — 1. the skin: 2. the subcutaneous tissue or superficial fascia : 3. muscles and their aponeurotic expansions : 4. a particular fibrous expansion, or fascia : 5. a thin and filamea- tous cellular tissue, which separates the fascia just named from the sixth element: 6. the peri- toneum, which, however, is not to be found in the composition of all the walls of the abdomen.

* Velpeau applies the term xone to the primary regions included between the horizontal lines. — Anat. Chirurg. t. ii.

ABDOMEN.

*3

In and between these several structures ramify the various arteries, veins, lymphatics, and nerves, which constitute the vascular and ner- vous supply to the abdominal parietes.

1. The skin on the anterior and lateral parts of the abdomen is thin and smooth, and in some parts covered with hairs, as along the middle line, especially below the umbilicus and over the pubic region. Along the median line the cutaneous follicles are largely developed, and during pregnancy an increased secretion of pigmentum is said to take place, producing a brownish colour of the skin in these regions. In women who have borne children, the skin becomes wrinkled to a considerable de- gree, and the epidermis exhibits, as Winslow has remarked, a great number of lozenge- shaped spaces disposed in a reticular manner.*

In the epigastric region the skin is much more sensitive during life than in the other parts of the abdomen, and with some persons sympathizes with the stomach in a remarkable degree, so that pressure on it even in the healthy state produces a degree of pain or un- easiness in that organ, or even a tendency to nausea. In the umbilical region we observe a depression, the floor of which is more or less elevated in the centre. This depression is de- nominated the navel or umbilicus, (the dimi- nutive of umbOj a nob or button.) It is produced by the firm adhesion of the skin to the subjacent structures, its true nature being that of a cicatrix, occupying the site of a former perforation through which the umbilical arteries and veins and the urachus passed in maintaining the circulation between the foetus and placenta. In very fat persons, the depth of the depression is often very much increased by reason of the great thickness of the abdomi- nal parietes, and in some instances its form assumes that of a slit, and sometimes, instead of a depression, there is a greater or Jess pro- minence of the integument.

In the lumbar region the skin is thicker and firmer than in the others; and we generally find it in a state of congestion after death, in consequence of the position of the body.

2. The subcutaneous cellular tissue on the anterior surface of the abdomen has obtained especial attention from anatomists, particularly that portion of it which is found in the hypo- gastric regions. It is denominated the superficial fascia,^ and is merely an expanse of cellular tissue possessing the same general characters

* Winslow's Anatomy, by Douglas, v. ii. p. 160.

t The application of the term fascia to the sub- cutaneous cellular investment in various parts of the body has occasioned no small degree of confusion among anatomists. A singular degree of confusion exists in Velpeau's description of this fascia : he observes in one place that the deep layers of the subcutaneous cellular tissue constitute the super- ficial fascia, and in the next page states that " the superficial fascia is nothing else than the cellular tissue condensed, whose laminae strongly applied one against the other, are ultimately reduced to somewhat of the aponeurotic form." I shall adhere to this latter definition, and consider superficial fascia as synonymous with subcutaneous cellular tissue. — Velpeau Anat. Chirurg. vol. ii. p. 4 and 5.

as that which is found in all other parts of the body ; it is continued upwards over the thorax, laterally into the region of the back, inferiorly along the thighs, and into the scrotum. It varies in thickness according to the quantity of fat which is deposited in its cells ;"* in some in- stances it has been known to possess a thick- ness of three inches. Thin but muscular subjects afford the best examples from which to study the superfical fascia of the abdomen : in such subjects we find it in general of a much denser character than in others, very strong and elastic and easily divisible into laminae, produced, no doubt, by the pressure which it experiences from the weight of the abdominal viscera, and the constant attrition occasioned by the action of the abdominal muscles. In the iliac region, immediately above Poupart's ligament, the density of this fascia is most conspicuous. Here some have regarded it as a nbro-cellular membrane ; but the opaque bands which give it a fibrous appearance are merely the walls of the membranous cells rendered thicker and denser than they are in other parts. I cannot agree with Beclardf that it presents almost all the characters of an aponeurosis, inasmuch as it differs from an aponeurosis in wanting the shining and regular surface, and in possessing a degree of elasticity which never belongs to aponeurotic expansions. The elasticity of the superficial fascia is remarkable, and is by some compared to the elastic expansion over the abdomen of the larger quadrupeds ; J the comparison, however, is inaccurate, inasmuch as they are two distinct tissues, the former being cellular, and the latter the aponeurosis of the oblique muscles, which in some degree parta.kes of the properties of the yellow elastic fibrous tissue (tissu jaune).

Inferiorly the superficial fascia moves freely over Poupart's ligament, and is continued over the thigh (see GROIN, REGION OF THE). Along the middle line it is very adherent to the sub- jacent aponeurotic structure (the linea alba) as well as to the skin, — a fact which may be remarked of the subcutaneous cellular tissue in other parts of the body, and which was long ago noticed by Bordeu, when he observed that the cellular tissue is constricted (etranglee) in all its median portion, and that its cells (ballons ou pouches) are closed over the axis of the body. When this superficial fascia is dissected off, a very thin layer of cellular membrane, perfectly diaphanous, is found to adhere to the subjacent aponeurotic expansion. This will be found particularly adherent over Poupart's ligament, and is that which is referred to by some ana- tomists (as Manec, Cloquet, &c.,) as a deep process of the superficial fascia which adheres to Poupart's ligament, and so forms a super- ficial septum between the abdomen and thigh. To see this layer the superficial lamina should be raised by commencing the dissection of it

* Cloquet says it is, as it were, decomposed by the deposition of fat. — Recherches Anat. sur les Hernies de 1'Abdomen, p. 11.

t Diet, de Medecine, art. abdomen.

j Vid. Blandin, Anat. Topog.

B 2

ABDOMEN.

below and carrying it upwards ; the expansion will then appear to arise from Poupart's liga- ment, and spread over the subjacent aponeuro- sis. In some subjects it is so thin as to appear to be little more than the proper cellular cover- ing of the muscle and its aponeurosis, but in others it assumes a considerable degree of density. It may be called the deep layer of the superficial fascia; it deserves attention from the fact that the femoral hernia, in its ascent on the abdomen, lies between it and the super- ficial layer. It is to this fascia that Scarpa must allude under the name of " aponeurotic web of the muscle of the fascia lata," and hence some have called it Scarpa's fascia.* The whole of the superficial fascia has been called Camper's fascia, because it was first fully described by that writer.f

On the posterior wall of the abdomen, in the lumbar regions, the cellular tissue is more abundant and more lax; here we frequently find it infiltrated with serous fluid, in conse- quence of the usual supine posture of the body after death. It is continuous above with the subcutaneous tissue in the dorsal region, and below with that in the gluUeal regions. It, too, is firmly adherent along the middle line to the lumbar spine anteriorly, and to the skin posteriorly.

3. Muscles and aponeuroses. — The abdo- minal parietes owe their thickness chiefly to the muscular lamellae and the aponeurotic ex- pansions, which enter into their composition. In the anterior and lateral walls we find on each side five pairs of muscles, of which four are constantly present. These are, 1, M. obli- quus externus ; 2, obliquus interims ; 3, trans- versalis ; 4, rectus abdominis ; 5, pyramidalis, which last is frequently absent.

1. Obliquus externus. (Obliquus descen- dens ; c&sto-abdominal ; ilio-pubi-costo-abdo- minal.)

When the superficial fascia covering the an- terior and lateral surfaces of the abdomen has been dissected away, this muscle is brought into view. It consists of a flat muscular portion, situated superiorly and posteriorly, and of a tendinous or aponeurotic lamella anteriorly and inferiorly, but which is largest and strongest in the latter situation.

The muscular portion of the external oblique is attached by separate fasciculi to the external surfaces of the eight inferior ribs, from the fifth to the twelfth inclusive. These fasciculi indigitate at their attachment with similar ones, of the serratus magnus, from the fifth to the ninth inclusive, and of the latissimus dorsi from the tenth to the twelfth. -From these points of attachment, described by most English anatomists as the origin of the muscle, the fibres pass obliquely downwards and forwards, with different degrees of ob- liquity, the middle fibres being the most ob-

* Vid. Scarpa on Hernia, by Wishart, p. 22 ; also Todd on Hernia, Dub. Hosp. Reports, vol. i.

S246 ; and Flood's plates of Inguinal and Femoral ernia. | Camper, Icones Herniarum, p. 11.

lique, the superior taking a direction nearly horizontally inwards, and the posterior ones passing nearly vertically downwards. The an- terior and middle fibres are inserted into the outer convex border of the aponeurotic lamella of the muscle, but the posterior are inserted into the outer lip of the two anterior thirds of the crista of the ilium by short tendinous fibres. The fibres of this muscle vary considerably in length, those which are highest up being the shortest, the middle ones the longest, and next in length the posterior fibres. The aponeurotic lamella of the external oblique muscle is found on the anterior part of the abdomen, both su- periorly and inferiorly. In the former situa- tion the aponeurosis is extremely thin and weak ; it is transparent, so that the upper extremity of the rectus muscle which it covers is visible through it. This, too, is the narrow- est portion of the aponeurosis, which increases in breadth, strength, and thickness as it de- scends. The aponeurosis, like the muscular portion, consists of a series of fibres, for the most part inclined obliquely downwards and inwards, excepting the superior ones, whose direction is horizontal. At several places these fibres are separated from each other so as to allow the subjacent muscle to be seen through the interval. At various parts the tendon is perforated by vascular apertures, which are oc- casionally so enlarged as to admit little peri- toneal prolongations to pass through them. Along the middle line, from the ensiform car- tilage to the symphysis pubis, the aponeurosis forms an interlacement with its fellow of the opposite side, and this interlacement with that of the subjacent aponeuroses constitutes the tendinous line called linea alba, which, as Velpeau observes, may be regarded as the centre in which all the fibrous elements of the abdomen terminate. Just above the symphysis pubis, the decussating fibres are not inter- mixed in the same manner as in other parts of the linea alba : there the bundle of one side crosses anteriorly or posteriorly to that of the other, without any union of fibres, to be in- serted into the pubis of the side opposite to that from which it came.

A little above and external to the pubis, a separation of the fibres of the tendon of the obliquus externus takes place, leaving an opening which is denominated the external abdominal ring, through which the rounded bundle composed of the spermatic vessels and duct (the spermatic cord) passes in the male, and the round ligament of the uterus in the female. The aponeurotic fibres which form the immediate boundaries of this opening are termed the pillars of the ring, of which one is superior, internal, and anterior, the other is in- ferior, external, and posterior, and passes behind the cord. External and inferior to this opening, we observe that the aponeurosis of the external oblique muscle is extended from the pubis to the anterior superior spine of the ilium. On the pubic side, the fibres, which are the same that form the inferior pillar of the ring, are in- serted into the spine of the pubis, and being

ABDOMEN.

reflected backwards, outwards, and a little upwards, they are likewise inserted into the linea ilio-pectinea, which commences at the spine of the pubis. The lower margin of the tendon is thus folded back a little as it arches over the excavation between the pubis and ilium, so as to present towards the abdomen a slight channel-like excavation, which affords origin to the muscular fibres of the internal oblique as well as to those of the transver- salis, whilst it has the appearance of a rounded ligamentous cord towards the thigh. In this manner is formed Poupart's ligament, which, contrary to what its usual name denotes, is not a distinct ligamentous cord, but the in- ferior margin of the external oblique stretched from pubis to ilium, and folded a little upon itself. By its superior margin it is continuous with the fibres of the tendon of the external oblique, which fall obliquely upon it ; by its in- ferior margin it is intimately connected with the fascia lata of the thigh ; externally it is inserted into the anterior superior spine of the ilium ; and by its pubic extremity it has three attachments, 1. to the body of the pubis; 2. to the spine of the same; and 3. to the linea ilio-pectinea, constituting what has been called GimbernaCs ligament, which has a sharp slightly crescentic margin directed backwards and outwards to- wards the femoral vessels.* (See GROIN, REGION OF THE.)

The external abdominal ring is a triangular opening, situated obliquely ; the superior angle being directed upwards and outwards, and its base, represented by a line uniting the pubic insertions of the two pillars, resting upon the pubis. The superior angle is formed evidently by the separation of the fibres of the aponeu- rosis, the primitive direction of which is the same as that of a perpendicular from the apex to the base of the triangle, viz. downwards and in- wards, (sacrad and pubad.) This separation, however, is strengthened, and the angle round- ed by some tendinous fibres which inter- sect the oblique ones nearly at a right angle, arising as a cord of variable thickness from Poupart's ligament, and passing upwards and inwards over the apex of the ring, gradually separating into several tendinous fibres. These fibres are sometimes very strong, at other times very feeble and scarcely perceptible ; but it rarely, if ever, happens that they are completely absent ; they have been termed intercolumnal bands. I have seen them so strong that they could be distinctly dissected off the external oblique aponeurosis, like a separate tendinous expansion; but most fre- quently they are so united to the aponeurosis as to render it impossible to remove them without injury to it. These fibres are evi- dently intended, as Scarpa expresses it, " to fix the limits of the inguinal ring, and to oppose the further divergence of the tendi- nous pillars towards the side." They are

* The terms crural arch, and ligament of Fallopius, are also used synonymously with Poupart's liga- ment. Velpeau calls it bandelette ilio-pubieune du grand oblique.

equally met with, although not nearly so much developed, in women and children as in men ; and Mr. Lawrence asserts that in old herniae they are particularly strong. I cannot confirm this remark from my own observation, as in my dissections of old herniae, I have not found them particularly developed; nor is it con- sistent with the general result of pressure from within on tendinous fibres to believe that such pressure would produce an increase of deve- lopment in them.

The size of the external abdominal ring is greatest in the male subject, but here it varies considerably, sometimes closely embracing the cord as it passes through it, and at others appearing much too large for it. In the male the parts which pass through it are the sper- matic cord, enveloped in its proper tunic, and in one of condensed cellular membrane pro- longed from the fascia transversalis, a branch of the genito-crural nerve, the cremaster mus- cle, the cremasteric artery, and the spermaticus superficialis nerve. In the female, we find the round ligament of the uterus, covered and accompanied by similar parts, excepting (he cremaster. From the margin of the external abdominal ring, a cellular expansion or fascia is carried over the cord or round ligament, and has been denominated fascia spermatica. This fascia consequently forms a covering of any hernia that may be protruded through the external ring; and, accordingly, in old herniae we find it greatly thickened. Its formation is simply in accordance with what we find oc- curring in all parts of the body, viz. that when any part passes through an opening in a fibrous membrane, it carries with it a cellular expan- sion from the margin of that opening. This we observe in the passage of the vena cava through the diaphragm, of the urethra through the triangular ligament or deep perineal fascia. This view confirms the opinion of Sir A. Cooper, that this fascia is a production from the margin of the ring itself.

The external oblique muscle is covered in all its extent by the superficial fascia ; its costal margin is related to the serratus magnus,and to the latissimus dorsi, with which muscle it is also in close relation by its posterior margin, being sometimes slightly overlapped by the anterior margin of the latissimus, but at others separated from that muscle by a triangular interval through which the fibres of the obliquus inter- nus appear: interiorly the fascia lata of the thigh is related to the margin of the external oblique muscle, both as it covers the glutaei,and as it lies in front of the thigh. Along the middle line the aponeuroses of opposite sides meet at the linea alba, and superiorly the mus- cular fibres are related to and sometimes con- nected by a fleshy slip with those of the pecto- ralis major, and the aponeurosis is continuous with that of the same muscle.* When the ex-

* " By its position, the direction of its fibres, and the short distance to which its fleshy portion extends forwards, the external oblique corresponds so much to the external intercostals, that one is led to say that it represents them in the abdomen," — Mechel.

ABDOMEN.

ternal oblique is removed from its osseous at- tachments, and raised inwards, it is found to cover the internal oblique, with part of the ten- don of which it is ultimately united as the two tendons approach the linea alba.

2. Obliquus internus (obliquus ascendens, ilio-abdominal, ilio-lumbo-costi-abdominal) is smaller than the preceding muscle, which it resembles in shape and general characters. The direction of its fibres, however, is opposite, inasmuch as the fibres of the two muscles decussate with each other, thus adding con- siderably to the strength of the abdominal wall, and forming a great protection against visceral protrusions. The external attachments (or, as systematic writers call it, the origin of the mus- cle) is 1. by short fleshy fibres to the tendinous expansion covering the lumbar mass of muscles, called fascia lumborum, which is formed by the posterior lamina of the tendon of the trans- versalis abdominis : 2. to the two anterior thirds of the middle portion of the crista ilii, between the external oblique and the transver- salis as far forwards as the anterior superior spine : 3. to the groove in the upper or abdo- minal surface of Poupart's ligament for about its external third. The superior fibres pass upwards and inwards, and are inserted by fleshy slips into the cartilages of the twelfth, ele- venth, and tenth ribs, in the intervals between which they are either separated from the inter- costal muscles by a fibrous intersection, or con- founded with them, and by a tendinous aponeu- rosis into the cartilages of the ninth, eighth, and seventh ribs as well as into the xiphoid cartilage. Lower down, the fibres which arise from the crista ilii, as well as those from Poupart's liga- ment, pass inwards, the superior obliquely upwards and inwards, the inferior more hori- zontally, and the lowest fibres inclining a little downwards, and are all inserted, like those of the obliquus externus into the outer convex margin of an aponeurotic expansion,, which goes to be inserted along the middle line. This ten- don passes inwards for a short distance, nearly as far as the outer margin of the rectus muscle, as a single lamina. Along this margin, and as low down as the inferior fourth of the rectus muscle, the tendon divides into two laminae, of which the anterior adheres to the posterior surface of the tendon of the external oblique, and the posterior to the subjacent tendon of the transversalis, both laminae going to be inserted into the ensiform cartilage and linea alba, the one in front, the other behind, the rectus muscle. (Seej%. 4, a. ) For a distance, however, corres- ponding to the inferior fourth of the rectus muscle, the tendon of the obliquus internus re- mains undivided, and does not adhere to that of the obliquus externus. It, however, is united, although not inseparably, to the tendon of the transversalis, and both go in front of the rectus to be inserted into the linea alba and pubis : these tendons are here called by some the con- joined tendons. Along the line at which the tendon of the obliquus internus divides into two laminae., the aponeurosis of the obliquus externus

and that of the trausversalis adhere to it more closely than they do externally to that line, and thus a thickened portion of the abdominal aponeurosis is formed, taking the course of the outer margin of the rectus muscle : this line is called the Linea semilunaris, and is that in which the operation of paracentesis abdominis used formerly to be practised.

The inferior margin of the obliquus internus is deserving of particular attention. The in- ferior fibres attached to the external third of Poupart's ligament in the groove formed in it pass transversely inwards and parallel to the ligament, crossing over the spermatic cord, to be inserted into the pubis. Here the muscle is confounded with the inferior fibres of the sub- jacent one, the transversalis ; so that it is not only difficult to say which muscle passes low- est down, but it is difficult, and often impossible, to separate the two muscles. Hence the lower margins of the fleshy fibres as well as of the apo- neuroses of these two muscles are constantly spoken of conjointly ; however, I have several times succeeded in separating them distinctly, and I am decidedly of opinion that the apo- neurosis of the obliquus internus seldom or never descends so low down as that of the trans- versalis. The lowest of the fibres of the obliquus internus are sometimes observed to separate a little from the others, so as, instead of a directly transverse, to assume a course slightly curved with the concavity upwards and a little outwards, lying in front of the cord ; in some cases fibres of this kind are observed to lie in front of th^ spermatic cord, and to descend much lower down, taking of course a much more curved direction, still attached on the outside to Pou- part's ligament, and on the inside to the pubis, so that a series of curved fibres are thus found to adhere to the anterior surface of the cord and of the tunica vaginalis, exhibiting an equal num- ber of reversed arches. But this disposition is rarely seen in its most highly developed state, excepting where some tumour has been con- nected with the cord or testicle, as hernia, hydrocele, &c.

This arched arrangement of muscular fibres in connection with the spermatic cord and tunica vaginalis testis constitutes the Cremas- ter muscle (K^^atu, suspendo,} the great tenuity of which in the natural state of the parts has ren- dered it difficult to determine its precise attach- ments, and consequently has given rise to the great discrepancy which is observable between the descriptions of different writers. When this muscle is examined in a case of old hernia or hydrocele, it is found, as Scarpa originally described it, to consist of two bundles ; the first, external to the cord which arises from Poupart's ligament along with the internal oblique, follows the course of the spermatic cord, which it ac- companies through the external abdominal ring, sending at intervals fibres arching in front of the cord to join a similar bundle on the inner side, as may be seen in the accompanying en- graving from a plate in Sir A. Cooper's work on the testis (fig. 3 ). Inferiorly, this bundle, a

ABDOMEN.

Fig. 3.

c, the internal oblique ; e, the descending fibres ; /, point, of insertion into the pubis ; h, one of the re- versed arches ; d, conjoined tendons ; a, rectus muscle.

good deal diminished in size, crosses over the inferior and anterior portion of the tunica vagi- nalis testis, and begins to ascend along the inner side of the testicle and cord, keeping more pos- teriorly : this constitutes the second bundle ; it gradually increases in size as it ascends by re- ceiving the transverse fibres from the bundle of the opposite side, and it is inserted, sometimes by a distinct tendon, into the pubis near its spine. In some cases I have totally failed, even after the most careful dissection, in detecting a conti- nuity by muscular fibre between these two bun- dles, insomuch as to lead me to imagine that they may be connected by a very condensed cel- lular tissue or thin aponeuro^c lamella after the manner of the digastric musaj^s. . In general the external bundle is largej^han the internal, but Cloquethas seen the re^K three times ; and on referring to my notes, I mjd I have seen two instances in which the internal bundle exceeded the external in size. V

Many anatomists have notic^ed only the ex- ternal bundle of the cremaster? and altogether overlooked its reversed arches, which is not to be wondered at when we remember that even where the lateral bundles are strong and well developed, the arched fibres are sometimes pale and thin. However, the description now given is pretty generally admitted as the true one, and is sanctioned by such observers as Scarpa, Cloquet, Cooper, Velpeau, and I may add that I have seen this arrangement in cases where both testicle and cord were healthy. It would appear that its formation is effected by the testicle in its descent, for before that takes place the muscle does not exist ; at least such is the result of Cloquet's observations on a con- siderable number of foetuses before, during, and after the descent of this organ. Before the de- scent the gubernaculum testis occupies the inguinal canal, and is covered by the fibres of the internal oblique, which adhere to it : when

the gubernaculum is drawn down, these fibres descend with it, forming a series of reversed arches.

In some female subjects we see an arrange- ment of the inferior fibres of the internal oblique as they cross over the round ligament, which resemble a rudimentary state of the cremaster muscle.

A thin layer of cellular tissue, sometimes containing a small quantity of fat, is interposed between the anterior surface of the obliquus internus and the obliquus externus. At the infe- rior edge of the obliquus internus the spermatic cord is seen emerging from the abdomen and passing obliquely inwards and a little down- wards to the external abdominal ring. Here it lies in a groove or channel, called the inguinal canal, which extends from the point at which the spermatic cord emerges from the abdomen, (the opening in the fascia transversalis called in- ternal abdominal ring) to the external abdo- minal ring. This canal is bounded or covered anteriorly by the tendon of the obliquus externus; posteriorly by the fascia trans- versalis and some fibres of the tendon of the transversalis muscle towards the inner side ; superiorly by the margin of the obliquus in- ternus and transversalis muscles ; and inferiorly by the groove of Poupart's ligament.* (A full description of this canal will be found in the article GROIN, REGION OF THE.)

3. Transversalis ( lumbo-abdominal, lumbo- ili-abdominal). This muscle is immediately under cover of the obliquus internus ; its name is derived from the transverse direction of its fibres. In its general character it resembles the obliqui, being like them a muscular lamella, inserted into a tendinous expansion, which again is inserted into the linea alba. Supe- riorly the fleshy fibres of this muscle are attach- ed by distinct bundles to the internal surface of the cartilages of the ribs forming the lower margin of the thorax, where these bundles in- digitate with those of the diaphragm : 2dly, in the interval between the last rib and the crista

Fig. 4.

* " The obliquus internus corresponds to the in- ternal intercostals by the direction of its fibres, by its being situated under cover of the obliquus externus, and because its fleshy fibres extend much further forwards than those of the last-named mus- cle. "—

ABDOMEN.

ilii, the fibres arise from a tendinous lamella, which itself is trifoliate in its origin. This ten- don is found as an undivided lamella between the outer margin of the quadratus lamborum and the commencement of the fleshy fibres of the muscle, extending vertically from the last rib to the crista ilii. ( Fig. 4, 1.) The three laminae of which this tendon is composed arise from different portions of the vertebrae in the lumbar region of the spine; the posterior, which is thick and strong, and is commonly called fascia lumborum, arises from the extremities of the spinous processes, and covers the lum- bar mass of muscles. (Fig. 4, g.) The mid- dle, which is weak, is attached to the apices of the transverse processes ; it lies in front of the lumbar mass and behind the quadratus lumbo- rum (Jig. 4, h); and the anterior arises from the pedicles which connect the transverse processes to the bodies of the vertebrae, and covers the quadratus lumborum muscle in front (Jig. 4, f). Inferiorly, the transversalis muscle at- taches itself to the inner lip of the crista ilii for its three anterior fourths, and to the ex- ternal third or half of Poupart's ligament, cor- responding to the attachments of the obliquus internus. The fleshy fibres of the muscle pass from these several points of attachment trans- versely inwards, the middle being the longest, and the superior the shortest, and are in- serted into the outer convex margin* of a tendinous aponeurosis, which extends to the linea alba. This aponeurosis is intimately connected with the posterior division of that of the obliquus internus for an extent corre- sponding to the three superior fourths of the rectus muscle, behind which both pass to be inserted into the ensiform cartilage and linea alba, (Jig. 4, a,) forming the posterior wall of the sheath of the rectus. Inferiorly, as we have already remarked, these conjoined tendons go together in front of the rectus, and are inserted into the inferior fourth of the linea alba and into the pubis. At the inner extre- mity of the inguinal canal, it will be seen by carefully raising up the spermatic cord, that this union of the tendons of these two muscles ceases, and we can trace the fibres of the trans- versalis tendon passing down in a curved direc- tion, more curved as they are more external, and insinuating themselves behind the cord to be inserted into Gimbernat's and Poupart's ligament for about its ^xternal third or fourth. This mode of insertion of the transversalis ten- don was first described by Sir Astley Cooper, f and these fibres were by him called thejblded fibres of the transversalis. They adhere to the subjacent fascia, (fascia transversalis,) and add to the strength of the inner portion of the pos- terior wall of the inguinal canal. They cor- respond, in a great measure, to the external abdominal ring, and may be counted as one of the obstacles provided against the direct descent of a hernia.

Such is unquestionably the usual mode of

* This margin forms the linea semilunaris of Spigelius.

t Cooper on the Testicle, p. 35.

insertion of the tendon of the transversalis muscle ; but Mr. Guthrie has lately called the attention of anatomists to a variety which it is important to know, although it cannot be of frequent occurrence. In this variety the spermatic cord appears to pass through a slit in the inferior margin of the transversalis muscle, so that a bundle of muscle passes behind as well as before the cord ; the posterior one end- ing in tendinous fibres, which, like the folded fibres above described, are inserted into Pou- part's ligament.* It is very generally believed that the inferior fibres of this muscle contribute, as well as those of the obliquus internus, to form the cremaster. The two muscles are so closely connected externally by their inferior margins, that it is natural to suppose that both do send fibres to the cremaster. Sir Astley Cooper expresses the relation of the cremaster to these two muscles in the clearest way, when he says that it arises from Poupart's ligament within the inguinal canal, and there blends with some of the fibres of both these muscles.f

A thin layer of cellular tissue covers the transversalis muscle, and separates it from the obliquus internus. At its superior margin it is intimately related to the diaphragm, and some of its fibres seem to be continuous with it : posteriorly, by the triple partition of its tendon, it ensheaths the lumbar muscles, and it lies upon the fascia transversalis, which, with a layer of cellular tissue, separates it from the peritoneum. |

4. Rectus abdominis (ster no-pub ien). After the superficial fascia has been removed so as to expose the aponeurosis of the external ob- lique, the recti muscles are seen on either side of the middle line covered by this aponeurosis, which it is necessary to slit up in order to ex- pose the muscles. The rectus owes its name to the perpendicular course of its fibres, which pass from the pubis to the thorax, nearly parallel to the middle line. It is long and narrow ; however, its breadth increases as it advances upwards, and as it increases in breadth it diminishes in thickness. At the pubis the muscle has its most fixed point of attachment, whence it is generally said to have its origin there: it arises by a short tendon from the symphysis of the pubis; this tendon is very narrow at its origin, but soon expands, and unites with the muscular fibres, which pass vertically upwards to the lower margin of the thorax, where the muscle is considerably increased in breadth, and divides into three portions; the first or internal one is inserted into the costoxiphoid ligament and cartilage of the seventh rib ; the middle, larger than the preceding, into the cartilage of the sixth rib at its inferior edge and anterior surface;

* Guthrie on Inguinal and Femoral Hernia, pp. 11, 12, 13, 4to. Lond. 1833.

t Op. cit. p. 38.

t " The transversalis corresponds, by the direction of its fibres, to the ' triangularis sterni ;' also, by its situation, by the attachment of its external edge to the internal surface of the ribs, and by that of its internal edge to the sternum and linea alba." — Mechel.

ABDOMEN.

and the external, the largest of the three, into the inferior edge of the cartilage of the fifth rib. This muscle is remarkable for its tendinous intersections, which cut the fibres at right angles, and are called linear transverse. ;* they vary in number from three to five, and are always more numerous above than below the umbilicus. In general there is one on a level with the umbilicus; the superior one being about an inch below the superior attachment of the muscle, and a third midway between these two : when a fourth and a fifth exist, they are below the umbilicus. They adhere to the an- terior wall of the sheath closely, and but very slightly or not at all to the posterior. Some- times the intersection does not go completely through the thickness of the muscle so as to appear on its posterior surface, and thus the posterior fibres are longer than the anterior; but as Bichat remarks, it never happens that any of the muscular fibres pass from one extre- mity of the muscle to the other without uniting at least one of these intersections. Sometimes, too, the intersection does not go through the breadth of the muscle, and this is generally the case with that below the umbili- cus. The effect of these intersections is to convert the muscle into so many distinct bellies, each of which has its proper action, and is, as Beclard asserts, provided with a separate nerve.f

The rectus muscle is enveloped in a fibrous sheath, the mode of formation of which the reader must have collected from the description of the oblique muscles. The anterior wall of this sheath is formed by the aponeurosis of the external oblique alone over the chest, and by the same aponeurosis and the anterior layer of that of the internal oblique, from the xiphoid cartilage to the inferior fourth of the muscle ; (both which aponeuroses over the internal half of the muscle are so adherent to each other as to form but one lamina;) and in its inferior fourth by the conjoined aponeuroses of the two obliqui and transversalis.

The posterior wall of the sheath is deficient superiorly where the muscle covers the carti- lages of the ribs with which it is' in contact, and inferiorly for a space corresponding to the inferior fourth of the muscle. So much of it as exists is formed by the tendon of the transver- salis and the posterior lamina of that of the internal oblique, so that the rectus appears to have passed at its inferior extremity through a transverse slit in these conjoined tendons, so as to get between them and the peritoneum.

The rectus muscle covers, at its superior ex- tremity, the cartilages of the two last true ribs and a part of those of the two first false, and also the xiphoid appendix. The internal mam- mary and epigastric arteries are found behind it in the sheath.

Between the recti muscles is the fibrous cord called linea alba, produced by the interlace-

* Also called enervations.— Window. They are, says Meckel, incontestahly incomplete repetitions of the ribs in the walls of the abdomen.

t Hence Meckel classes it among the polygastric muscles.

ment of the aponeuroses of the opposite sides, noted in surgery as being in its inferior half the seat of the operations of paracentesis abdominis, paracentesis vesicse supra pubem, the supra- pubic lithotomy, and the Caesarean operation. This cord extends from the xiphoid cartilage to the symphysis pubis, with the anterior liga- ment of which articulation it is identified. It does not present the same breadth in its whole course, being broader in the umbilical region than elsewhere. In this region we find in the linea alba the perforation which gave passage to the umbilical vessels in the foetus and the urachus, and through which the fibrous remains of those vessels pass to be inserted into the skin, whereby is formed the cutaneous depres- sion which marks the situation of this opening. In the adult the umbilicus may be considered as a point of considerable strength ; in the esti- mation of some it is the strongest point in the abdominal parietes : in dissecting away the skin at this point, we find subjacent to it a very con- densed cellular tissue, to which and to the skin the fibrous cords into which the umbilical vessels have degenerated adhere closely ; these cords, too, adhere not only to the skin, but likewise to the margin of the. fibrous ring through which they pass. " The umbilical opening, therefore," says Scarpa, " in the infant two months after birth, and still more in the adult, is not only like the other natural openings of the abdomen, strength- ened internally by the application of the peri- toneum and of the cellular substance, and on the outside by the common integuments, but it is likewise plugged up in the centre by the three umbilical ligaments and by the urachus; these ligaments form a triangle, the apex of which is fixed in the cicatrix of the in teguments of the umbilicus, the base in the liver, in the two ilio-lumbar regions, and in the fundus of the urinary bladder ; by this triangle is formed a strong and elastic bridle, capable of itself alone of opposing a powerful resistance to the viscera attempting to open a passage through the aponeurotic ring of the umbilicus, which apparatus does not exist at the inguinal ring or femoral arch."*

In the foetus the ring of the umbilicus is proportionally larger than at any period after birth when the cicatrix is fully formed : it is, however, at the full term, or even at the seventh or eighth month, and in the healthy state of the parts, equally filled up by the umbilical vessels and urachus, and we would say is equally capable of resisting intestinal protusion as at any subsequent period. Hence it may be in- ferred that congenital umbilical ruptures are always of very early date, being attributable to the persistence of the opening at the umbilicus, and the continuance in it of the intestinal pro- longation which exists there naturally at a very early period. It may likewise be inferred that the rupture in the adult can much more easily occur in the vicinity of, than through the umbi- lical ring; and experience confirms this deduc- tion from the anatomy of the parts.

* Scarpa on Hernia, p. 373.

10

ABDOMEN.

Above the umbilicus the linea alba is from two to four lines broad in the greater part of its extent; and below the umbilicus it gradually tapers down to the pubis, at the same time in- creasing in thickness.*

5. Pyramidalis ( pubio-sub-umbilical ) . At the inferior extremity of the recti, and separa- ting their origin, are two small muscles of a pyramidal form; their bases are inferior, and attached to the symphysis and body of the pubis, and uniting ligaments, and their apices superior and inserted into the linea alba by small tendons, from two to three inches above the symphysis pubis. Each muscle is enve- loped in a distinct sheath, and lies a little more prominently than the origin of the rectus of the same side. These muscles are not unfrequently absent. Sometimes, on the contrary, there have been two on one side and one on the other, or even two on each side.f

The muscles which enter into the composi- tion of the posterior wall of the abdomen are chiefly those which occupy the lumbar region of the back, filling up that empty space which in the skeleton is observed on each side of the spinal column between the crista ilii and the last rib. In dissecting from behind forwards in this region, having removed the skin and lax cellular tissue already described, we come upon the strong fibrous expansion, the fascia lumbo- rum. This has extensive osseous attachments, and thus firmly binds down the subjacent mus- cles. When it is removed, the lumbar portions of the sacrolumbalis and longissimus dorsi, and a little of the spinalis dorsi, are brought into view, the two former of which are described by some as a single muscle — the sacrospinalis. The external of these muscles is the sacrolum- balis, and its outer margin may be said to con- stitute the limit of the posterior wall of the abdomen in that direction. In this situation the posterior and middle layers of the tendon of the transversal is separate from each other to ensheath these muscles, the posterior layer forming the fascia lumborum. We must refer to the article BACK for a particular description of these muscles.

When the lumbar mass of muscles (as the three preceding have been called) has been re- moved, the next part brought into view is the anterior layer of their fibrous sheath formed by the middle lamina of the transversalis tendon, which is inserted into the apices of the trans- verse processes. This lamina is thin and semi- transparent, so that the fibres of the muscle

* " The linea alba performs the same office in the abdomen as the sternum does in the thorax, with this only difference, that it is not formed of bone. The anterior tendons of the broad muscles are at- tached to it, in the same way that the cartilages of the ribs are articulated with the sternum, and the difference of tissue which exists between it and the sternum is attributable to the general difference of structure between the abdominal and pectoral cavi- ties, the latter being formed almost entirely of osseous parts, whilst the walls of the former are fleshy and tendinous/' — Meckel.

t Meckel says that this muscle rarely presents anomalies ; in this he must be mistaken, as its ab- sence is ceitainly not a rare occurrence.

which lies immediately before it, are seen through it. This muscle is the

Quadratus lumborum (ilio-costal, ilio-lumbi- costal). The term quadratus is applied to this muscle, more from its quadrilateral form than from any nearer resemblance to a square, in- asmuch as all its sides are unequal. The most fixed attachment of this muscle is its inferior, where it is inserted by tendinous fibres into the iliolumbar ligament and into the inner lip of the crista ilii for about an inch to the outer side of the insertion of that ligament. From these points the fibres proceed vertically upwards, the ex- ternal ones going to be inserted into the inferior margin of the last rib for nearly its entire length, and the internal fibres, those in parti- cular which are attached to the ligament, ter- minating by four aponeurotic tongue-like bun- dles, which are inserted into the anterior surface of the transverse processes of the four superior lumbar vertebrae near their bases. The several bundles which end in these tongue-like pro- cesses vary in length ; those which are external being the longest, as going to higher vertebrae. This muscle is covered on its anterior or abdo- minal surface by the anterior lamina of the tendon of the transversalis muscle, by which it is separated from the diaphragm as well as from the psoas magnus.* The last dorsal nerve and the first two branches of the lumbar plexus, pass between the quadratus and the aponeurotic lamina which covers it.

Psoas magnus, (-»]/oa, lumbus) (prelombo, trochanterien, lumbaris.) The greatest por- tion of this muscle belongs to the abdominal region ; it lies along the side of, not only the lumbar but also of a small portion of the dorsal region of the spine, lodged in the angle between the transverse processes and bodies. It passes as high up as the twelfth dorsal vertebra, to the body of which as well as to those of the four suc- ceeding lumbar vertebrae, and to their interven- ing fibro-cartilages, the muscle is attached : it likewise is attached to the bases of the corres- ponding transverse processes, so that the inter- vals between the portions that are attached to the bodies, and those to the transverse processes, correspond to the intervertebral foramina or points of exit of the lumbar nerves, the an- terior branches of which plunge at once into the substance of the psoas muscle to form the lumbar plexus. The several bundles which thus take their origin from the vertebrae form a thick rounded muscle, which passes nearly vertically downwards, inclining a little out- wards, over the brim of the true pelvis, so as often to appear to encroach upon the circum- ference of the upper outlet of that cavity. A little way above Poupart's ligament the mus- cular fibres are inserted around a strong thick tendon. This tendon, which had commenced high up by distinct portions in the interior of the muscle, passes under Poupart's ligament over the horizontal ram us of the pubis. It descends over the capsular ligament of the hip-

* See Jig. 4,y; see also fig. 5, where on one side the muscle has been removed from between the laminae of the transversalis tendon.

ABDOMEN.

11

joint (from which as well as from the ramus of the pubis it is separated by a bursa) over the head and along the inner side of the neck of the femur, and is inserted into the posterior part of the trochanter minor at its base, being separated by a small bursa from the surface of that process. As the tendon is passing over the ramus of the pubis, it receives by its outer margin a series of fibres from the iliacus in- ternus muscle. At its superior portion the psoas muscle is covered by a thin fibrous ex- pansion, which is attached on the one hand to the apices of the transverse processes, and on the other to the bodies of the upper lumbar vertebrae ; this expansion, the arcus interior of Senac and Haller,* also called ligamentum arcitatum, separates the psoas from the dia- phragm. Below this the psoas muscle is covered with a lax, and in some degree fatty cellular tissue, which separates the muscle from the kidney externally, and from the peritoneum and ureter within, excepting where the psoas parvus covers it, and on the right side where the vena cava lies upon it. Along its internal margin are the lumbar portion of the sympathetic, the crura of the diaphragm, more especially on the left side, and on this side too the aorta ap- proaches a little its internal margin. The common and external iliac arteries and veins lie along the internal margin of the pelvic portion of the muscle, which is covered by the fascia iliaca. The several branches of the lumbar plexus issue from this muscle at its external margin, and the genito-crural nerve descends in front of it inferiorly. We refer to the article on the muscles of the thigh for a further account of this muscle, its relations in the upper part of the thigh, and its actions.

Psoas parvus, (prelombo-pubien). This muscle is similar to the psoas magnus in course and position. It is very much elongated, its fleshy portion being small and tapering. Su- periorly it is attached to the body of the first lumbar vertebra, and to the intervertebral sub- stance between it and the last dorsal, and sometimes to the body of the last dorsal ver- tebra. The fleshy belly soon ends in a flattened tendon, which descends obliquely downwards and outwards over the anterior surface of the psoas magnus, and at its inferior extremity ex- pands considerably, and is inserted along the linea ilio-pectinea near the junction of the ilium and pubis. An expansion from the margins of this tendon becomes united on the outside to the fascia iliaca, and on the inside to the internal portion of the same fascia which covers the great psoas, and passes beneath the iliac vessels to become united at the brim of the pelvis to the pelvic fascia.

We must not omit to state that the crura of the diaphragm, as they descend over the bodies of the lumbar vertebrae, (see DIAPHRAGM,) may be regarded as entering into the formation of the posterior wall of the abdomen. The inferior wall of the abdomen is not devoid of muscle, although those muscles can exercise very little, if

* Vid. Haller Icon. Scpti Transversi. Op. Minora, torn. 1.

any influence upon the contents of the cavity. The iliac fossa affords a large surface for the attachment of one of the principal muscles connecting the thigh with the trunk. This muscle is named

Iliacus internus, (iliaco-trochanterien.) This muscle fills up the iliac fossa, to the whole of whose concavity as well as to its margin, and the two anterior spinous processes of the ilium and the interval between them, its fibres are attached. From these several points of origin the fibres converge to form a thick and broad belly, which passes over the upper part of the acetabulum and horizontal ramus of the pubis, filling up the external portion of the upace between that bone and Poupart's ligament ; and it is inserted, as we have already observed, into the outer margin of the tendon of the psoas magnus, which is for thgt reason gene- rally described as the common tendon of the psoas and iliacus. The anterior surface of this muscle is traversed by two of the external branches of the lumbar plexus (inguino-cuta- neous), and the anterior crural nerve passes between its internal margin and the psoas magnus.

The superior wall of the abdomen is entirely formed by the muscular vault of the diaphragm, which by its contraction and relaxation exer- cises a considerable influence on the abdominal contents, and causes very obvious changes in the form of the cavity. The concavity of this vault is towards the abdomen, and is greater on the right side than on the left, in consequence, as it is said, of the presence of the liver on that side. It is through the several openings in this wall that a communication is established be- tween the thorax and abdomen. The largest of these openings are, that on the right side, which is completely tendinous, for the passage of the vena cava; the opening for the reso- phagus; and that for the aorta; in addition to these there is a small one behind the centre of the xiphoid appendix formed by a divarication of the anterior fibres of the dia- phragm, through which the cellular tissue of the anterior mediastinum communicates with the abdominal subserous tissue. There are, moreover, openings for the transmission of the splanchnic nerves, and the continued trunks of the sympathetics, as well as of branches of the phrenic arteries and nerves, and the abdominal branches of the internal mammary. The par- ticular description of this muscle will be given under the article DIAPHRAGM.

4. The next element which enters into the formation of the abdominal parietes is a fibro- cellular expansion, which, varying in density in different situations, lines the whole internal surface of the muscular walls. It is strongest and exhibits most of the real fibrous character in the iliac region on the anterior wall, and over the iliac fossa in the inferior. In the former situation it has received the name of fascia transversalis, which was applied to it by ' Sir A. Cooper in consequence of its close con- nexion with the transversalis muscle : in the latter, it is called the fascia iliaca, from its connexion with the iliac fossa and muscle.

12

ABDOMEN.

The fascia transversalis is best seen by re- moving the muscles which lie anterior to it : it is then distinctly observed to extend from the outer margin of the rectus muscle internally over the posterior surface of the anterior wall of the abdomen, and gradually to assume the character of a thin but condensed cellular la- mella over the abdominal surface of the lateral wall : it may, however, be traced internally as far as the linea alba behind the rectus muscle, but here it is extremely thin, and has totally lost the fibrous character. Inferiorly this fascia adheres to Gimbernat's ligament and to the reflected margin of Poupart's, from which it is said, by some French anatomists, to originate. Along the line of Poupart's ligament and ex- ternal to it along the crista ilii, this fascia is united with the fascia iliaca, the union be- ing indicated by a white opaque line formed by a thickening of the membrane, taking the course of Poupart's ligament and the crista ilii, except where it is interrupted for the passage of vessels or other parts. Superiorly, the fascia transversalis also degenerates into a cellular lamella, which passes on the transversalis muscle to the diaphragm. It is for a short distance above Poupart's ligament that this fascia demands most attention ; here it forms the posterior wall of the inguinal canal, and at a point a little external and superior to the middle of Poupart's ligament it presents an opening or separation of its fibres, through which the sper- matic vessels and vas deferens united by lax cellular tissue pass into the inguinal canal, carrying around them a funnel-shaped mem- brane which seems to be a prolongation from or continuation of the margins of this opening, but which is in texture merely a condensed cel- lular layer. This prolonged membrane is the first covering which the spermatic cord receives upon its formation, which takes place as its several constituent parts meet at the opening or slit in the fascia transversalis ; it immediately invests the cellular tissue connecting these parts, which is the tunica vaginalis of the cord ; as it proceeds, the cremaster muscle adheres to it from the external oblique and transversalis muscles, and this again receives at its exit through the external abdominal ring another cellular expansion, to which we have already alluded.

The opening or slit in the fascia transversalis which we have just described is denominated by anatomists the internal abdominal ring, although, if we speak with reference to the mid- dle line, it is external to the opening in the tendon of the obliquus externus, which is called the external ring. It would certainly be more consistent with the ordinary use of these ad- jectives in anatomy to reverse their application, or if the term anterior were applied to the ex- ternal ring, and posterior to the internal, every purpose would be answered.

The direction of the internal abdominal ring is vertical and inclined very slightly outwards. When the fibrous character of the fascia trans- versalis is obvious, we can generally observe two very distinct portions of it, one on each side of the ring. The fibres of the external

portion pass upwards and inwards ; those of the internal portion, which are generally stronger and more developed than in the external, pass upwards and outwards so as to decussate with the external fibres at the upper extremity of the ring. The outer margin of this internal portion often presents towards the ring a lunated ap- pearance, over which the vas deferens turns at a sharp angle ; it can be best seen by examining the parts from behind after the peritoneum has been removed.* The fascia transversalis is continued upwards along the posterior and lateral surface of the abdominal muscles and over the diaphragm under the form of a fine lamina of very condensed cellular membrane, which adheres pretty closely to the muscles, but especially to the diaphragm, where it seems to be incorporated with the proper cel- lular covering of that muscle. We refer to the article GROIN, REGION OF THE, for further particulars respecting the fascia transversalis.

In the iliac fossa we find a very distinct fibrous expansion covering the whole abdo- minal surface of the iliacus internus muscle. This is tine fascia iliaca. It is seen by raising the peritoneum and the subperitoneal cellular tissue from the fossa. Inferiorly this fascia is connected with the fascia transversalis along the line of Poupart's ligament, except where that connexion is interrupted by the passage of the vessels under the ligament. That space comprises the interval between the inner margin of the tendon of the Psoas and Gimbernat's ligament; and here the fascia lies close to the horizontal ramus of the pubis, and passes be- hind the vessels into the upper part of the thigh, where it adheres to the linea ilio-pectinea, and seems to become continuous with the fascia lata. Externally the fascia iliaca is con- tinuous with the fascia transversalis along the crista ilii, where an opaque line indicates the union, and just internal to which it splits to ensheath the circumflexa ilii artery. On the inner side of the iliac fossa this fascia unites with the pelvic fascia along the brim of the pelvis, this union being likewise indicated by an opaque line similar to that already noticed along the crista ilii. To arrive at this point the fascia, in proceeding from without inwards, passes over the iliacus internus, then over the psoas magnus and parvus, upon which it is thinner than elsewhere ; it then passes behind the iliac artery and vein, and arrives at the pelvic margin. Posteriorly this fascia is con- tinuous with a thin and less fibrous expansion which covers the psoas and quadratus lumborum muscles, adheres to the ligamentum arcuaturn, and is identified superiorly with the cellular expansion on the diaphragm, and externally with the fascia transversalis.

It has already been stated that the iliac fascia passes behind the iliac vessels. These vessels have also anterior to them a fibrous or cellulo- fibrous expansion, which is connected on the inner and outer side to the fascia iliaca. Some

* This lunated margin is very well delineated by Cloquet in the third figure of the first plate annexed to his work on Hernia, now translated by Mr. A.M. M'YVhinuic.

ABDOMEN.

13

consider this as merely a portion of the subperi- toneal cellular tissue, but I cannot help regard- ing it as a process from the iliac fascia itself to envelope the vessels just as that fascia envelopes the circumflexa ilii artery between two lamina at its outer margin. I have never seen an in- stance in which this sheath was not perfectly dis- tinct, in some cases it is of considerable strength, but in the majority weak and transparent. It was this slveath which impeded Mr. Abernethy in one of his earliest operations for applying a ligature to the external iliac artery.*

The connexion which the iliac fascia has with the fascia transversalis at the crural arch, and the relation both bear to the iliac vessels at their exit to become femoral, suggested to Mr. Colles a comparison which is constantly referred to by anatomists. " It may be said to resem- ble," he says, " a funnel, the wide part or mouth of which occupies the hollow of the ilium and lower part of the abdominal muscles, and the narrow part or pipe of which passes downwards on the thigh. The mouth of this funnel may be supposed to rise as high as the upper edge of the iliac muscle, and to be turned toward the cavity of the abdomen : the pipe joins the wide part where the external iliac vessels are passing under Poupart's ligament, and it is continued down on the thigh, so low as to reach the insertion of the saphena into the femoral vein."f

From the preceding sections it appears that a fibro-cellular expansion lines the whole in- ternal surface of the abdominal parietes. It is so likewise with the pelvis, and also with the thorax. The cavity of the cranium, too, is lined with a fibrous membrane,, although of a different nature, and doubtless performing a dif- ferent office.

5. Between the internal fibrous expan- sion of the abdomen and the peritoneum is a cellular tissue, which presents different cha- racters in each region ; it is the subperitoneal cellular tissue. Along the anterior wall it is thin and fine, except inferiorly opposite the in- ternal abdominal ring, where it becomes more abundant, as well as in the hypogastric region, immediately above the pubis. In the iliac fossa and lumbar region it is lax and abundant, especially in the latter, where there is also a considerable quantity of fat surrounding the kidney. In the iliac fossa this cellular tissue is stretched across the crural ring, and forms what Cloquet describes under the name of septum crurale. On the superior wall it is ex- tremely fine, and in very small quantity. Im- mediately behind the sternum, and in the mid- dle line, this cellular tissue communicates with that of the mediastinum through a separation of the anterior fibres of the diaphragm.

This subserous cellular tissue forms the pri- mary covering of all herniae, which push a peritoneal sac before them, and as being the fascia constituting the nearest investment of the sac, it is generally called the fascia propria.

* Abernethy's Surgical Works, vol. i. p. 225. t Colics' Surgical Anatomy, pp. 68, 69.

Opposite the crural canal this cellular tissue is often so abundant, as, when condensed by the pressure of the hernial tumour, to form an ex- pansion over the sac of considerable thickness. Sometimes it contains fat, and not unfrequently we find a large lymphatic ganglion in it, filling up the crural ring.

6. Peritoneum. — A considerable part of the abdominal surface of the walls of the abdomen is lined by a very fine transparent serous mem- brane— the peritoneum, which is likewise con- nected, to a greater or less extent, with every viscus within the cavity. In consequence of this double connexion, it happens that in various situations the peritoneum is reflected from the wall of the abdomen upon an adjacent viscus, and thus are produced various folds of this mem- brane, which demand the attention of the ana- tomist. These folds are rendered distinct when such a section of the anterior abdominal wall is made as without dividing them to allow of it being held apart from the viscera. I shall enumerate these folds in describing the relation of the peritoneum to the several walls. The anterior wall of the abdomen is entirely lined by peritoneum, and has in connexion with it four folds, all of which, as it were, radiate from the umbilicus. In the adult these folds are reflected round four ligamentous cords (three of which are the remains of bloodvessels in the foetus), which meet at the umbilicus and diverge, one upwards, backwards, and to the right side (the obliterated umbilical vein), two downwards and outwards towards Pou- part's ligament on each side, so as to pass behind the inguinal canal, nearly midway between the two rings (the obliterated um- bilical arteries), and the fourth nearly ver- tically downwards along the middle line to be inserted into the apex of the bladder (the ura- chus). The four folds are similar in direction to that of the fibrous cords contained within them : the fold which passes upwards towards the liver is falciform, the concavity being di- rected downwards and backwards. From its connexion with the convex surface of the liver it is also called the falciform ligament of the liver, and the fibrous cord contained in its in- ferior margin, the ligamentum teres. The in- ferior and external folds pass each from the umbilicus, downwards and outwards to the iliac fossa, to a point a little on the inner side of the internal abdominal ring, where it dis- appears, being continued externally over the iliac fossa, and internally behind the rectus muscle. This fold, when stretched towards the umbilicus, evidently forms the partition between two pouches, the external and in- ternal inguinal pouches, which correspond re- spectively to the internal and external abdo- minal rings, and indicate the situations at which make their escape those two forms of inguinal hernia, which, from their connexion with these pouches, are called by Hesselbach external and internal inguinal hernias ; the for- mer being that by oblique descent, the latter that by direct descent.

The fourth or vertical fold indicates the

14

ABDOMEN.

reflection of the peritoneum from the anterior abdominal wall upon the superior fundus and posterior surface of the bladder : when that viscus is empty and contracted, this fold dis- appears totally ; it is more apparent when the bladder is partially filled, and is still more distinct in the foetus in consequence of the greater size of the urachus at that period. Just above the pubis the peritoneum is con- nected to the abdominal wall by a very lax cellular tissue; and accordingly when the blad- der is much distended, the peritoneum is pushed upwards, and stripped off the abdo- minal wall to an extent proportioned to the degree of distension of the bladder, so that its anterior surface is then in immediate contact with the abdominal wall, and may be opened with impunity so far as the peritoneum is con- cerned.

The lateral walls of the abdomen are like- wise completely lined by peritoneum, which extends backwards as far as the junction of these walls with the posterior, where it is re- flected from them so as to involve the ascending colon on the right side and the descending on the left, and here it forms on each side the folds respectively termed right and left meso- colon. From the right lateral wall the peri- toneum is continued upwards upon the dia- phragm, and contributes to form the right lateral ligament of the liver ; on the left side it is continued in a similar manner on the diaphragm, and in passing from the spleen to that muscle forms the fold called splenico- phrenic.

The concave surface of the diaphragm is in greatest part lined by peritoneum : the an- terior half of the muscle is uninterruptedly covered by peritoneum, which adheres very closely to the central tendon, but is much more easily separated from the muscular portion. On the right side and in the middle, in front of the cesophageal opening, the peritoneum is re- flected from the diaphragm to the liver, forming the right lateral, coronary, and left lateral liga- ments of that organ. The posterior half of this surface is likewise covered by peritoneum, that membrane being deficient for a little way behind the opening for the vena cava and behind and on each side of the cesophageal and aortic openings : the crura of the diaphragm are covered chiefly on the outer side.

The peritoneum comes into immediate con- tact with the posterior abdominal wall only in a very small portion of its extent : in tracing it on the right side we find it covering the right colon, then passing inwards over the kidney and suprarenal capsule, the duodenum and vena cava, to the eras of the diaphragm above, and in the middle and below, where it also covers the vena cava, and the renal vessels, to form the right or superior lamina of the mesentery. On the left side it covers in a similar manner the left colon, the left kidney and capsule, and that portion of small intestine which projects just to the left of the superior mesenteric artery, which may be regarded as the commencement of the jejunum ; below this it manifests its

continuity with the layer of the opposite side by forming the left or inferior lamina of the mesentery. This lamina commences at the left side of the body of the second lumbar vertebra; as it descends, it gradually crosses more in front of the aorta, so as to terminate at the right sacro-iliac symphysis ; the right lamina is situated quite on the right side of the spine.

In the iliac fossae the peritoneum is in con- nexion with the fascia iliaca, except where it is separated by the coecum on the right side (on which side it sometimes forms a fold termed mesoccecum,} and by the sigmoid flexure on the left. Internal to these portions of intestine on each side, the peritoneum covers the ex- ternal iliac artery and vein, from which it is separated by a very loose and sometimes adi- pose cellular tissue, and by a process of the iliac fascia, to which allusion has already been made.

From the preceding description of the con- nection of the peritoneum with the parietes of the abdomen, it will appear how few are the situations at which the surgeon could cut through any portion of these walls without risk of wounding the serous membrane. Im- mediately above the pubis this may be done in consequence of the abundance of cellular membrane there which separates the serous membrane from the wall ; but in the con- tracted state of the bladder the operator must proceed with the greatest caution : in the dis- tended state of that viscus, however, the wall of the abdomen is deprived of its lining to an extent proportionate to the height to which the bladder ascends behind the recti muscles; and accordingly it is under such circumstances that the paracentesis vesicae supra pubem, and the high operation for the stone may be per- formed with impunity to the serous membrane. At the posterior wall an instrument may be passed into any part of the posterior surface of the kidney without injury to the peritoneum ; the pelvis of the kidney, or any part of the abdominal course of the ureter, may be opened too, or the vena cava ; and by cutting into the bodies of the vertebrae, and the muscular por- tion of the posterior wall in the dead body, a view of all the parts which lie upon that wall may be obtained without at all injuring the peritoneum.*

Further details respecting the anatomy of the peritoneum will be found in the article under that head.

Vessels and nerves of the abdominal walls. — a. The arteries. — The most important arterial ramifications are found in the anterior wall. In the superficial fascia we find the superficial epigastric artery or tegumentary artery, which exists as a trunk in the iliac regions. This artery, arising from the femoral, pierces the fascia lata, and passes over Poupart's ligament upwards and inwards, crossing the anterior

* The reader may examine with advantage, Lud- •wig, Icones cavitatum thoracis et abdominis a tergo apertarum. Leipzig, 1789.

ABDOMEN.

wall of the inguinal canal between the two rings ; it is distributed in the integuments and fascia of the iliac and umbilical regions, and anas- tomoses with its fellow of the opposite side, and by deep branches which pierce the aponeuroses, with the deep epigastric artery. In the epigas- trium and hypochondria the superficial fascia and integument are supplied by cutaneous branches from the internal mammary and the inferior intercostals. The deep-seated parts of this region are likewise supplied from the last- named arteries ; the largest and most constant of which is the abdominal branch of the internal mammary, which in the sheath of the rectus supplies that muscle, and establishes an im- portant communication with the epigastric : this anastomosis is said to have been known to Galen, who by it proposed to account for the sympathy which exists between the uterus and the breasts.* Another branch of the mammary supplies the muscles external to the rectus ; it runs between the obliquus internus and trans- versalis, and is lost in anastomosing with the inferior intercostal, the lumbar, and the circum- flexa ilii arteries.

Inferiorly, the abdominal wall is supplied by two considerable and very constant arteries, viz. the epigastric, which may be distinguished from the artery that supplies the integuments by the appellation deep, and the circumflexa ilii. The epigastric artery arises in general from the external iliac a little way above Poupart's liga- ment; it at first inclines downwards to that ligament, and then turns upwards, and directs itself forwards and inwards, crossing the iliac vein; it then runs along the posterior surface of the anterior wall of the abdomen, inclosed be- tween the peritoneum and fascia transversalis, at first situated between the external and inter- nal abdominal rings, and on arriving at the rectus muscle, the sheath of which it enters about two inches above the pubis, it gives off branches from either side to the abdominal muscles and peritoneum, and behind the linea alba, establishes a very free inosculation with its fellow of the opposite side. As it lies behind the inguinal canal, the epigastric artery is much nearer to the internal than to the external abdo- minal ring, being to the pubic side of the former ; here the vas deferens, as it passes up from the pelvis to the inguinal canal, hooks over it, and receives one or two small branches from it. In passing to the rectus muscle, this artery lies internal to the linea semilunaris. It enters the sheath of the rectus, and then termi- nates by anastomosing with the internal mam- mary. The course of this artery demands par- ticular attention from the surgical anatomist in reference to the operations for inguinal herniae, and to that for paracentesis abdominis, when the abdomen is perforated in the linea semilu- naris. The trunk of the artery is so distant from the linea alba in its whole course, that it is free from danger in any operation performed in that line, or in the internal half of the rectus muscle, and its security in such operations is increased under the altered state of parts con-

* Diet, de Medecine, art. Abdomen.

sequent on pregnancy, ascites, or any abdomi- nal tumour pressing similarly on the abdominal wall. In these cases the distance of the artery from the linea alba is increased by the flattening of the rectus muscle, which results from its compression. — (See GROIN, REGION OF; HERNIA; ILIAC ARTERY.)

The circumflexa ilii artery comes likewise from the external iliac, near to the origin of the epigastric; it passes upwards and outwards to- wards the spine of the ilium, runs along the line of junction of the fascia iliaca with the fascia transversalis, covered by the fascia, and follows the circumference of theiliacus internus muscle to end in anastomosing with the iliolum- bar artery. From that part of the artery which intervenes between its origin and the spine of the ilium, come the principal branches which it supplies to the abdominal muscles.

The lateral and posterior walls of the abdo- men are supplied by the inferior intercostals, the lumbar, the iliolumbar, the circumflexa ilii arte- ries; the superior walls by the phrenic branches of the internal mammary and by those of the aorta. It is in cases where the aorta has been obliterated that we can see best the extent of arterial ramification on the abdomen, and can appreciate the benefit of these numerous anas- tomoses, and the connexion which they esta- blish between the upper and lower portions of the aorta.*

b. The veins. — The veins of the abdominal parietes are much more numerous than the arteries ; each artery has its accompanying vein or veins, but those which are especially de- serving of attention are the tegumentary veins which accompany the superficial epigastric artery, and those which ramify along with the deep epigastric and mammary. The subcuta- neous veins demand attention in consequence of the considerable size which they sometimes attain ; this enlargement is commonly attendant on ascites and on pregnancy, and is occasionally, to a remarkable extent, a consequence of some irregularity, obstructionf or retardation of the circulation, in the deep-seated veins of the ab- domen, more especially the inferior vena cava. The veins which accompany the superficial epigastric artery empty themselves by one or more trunks into the vena saphena at the upper part of the thigh.

Two veins generally accompany the deep epigastric artery, which empty themselves into the external iliac vein. These veins are equally subject to enlargement with the preceding, and from similar causes, and they are often found in a varicose condition in women who have borne many children.

Some curious anomalies have been observed in the venous circulation of the anterior abdo- minal wall, which, as being calculated to in- terfere with the operator, the practitioner would

* See the interesting case of obliterated aorta re- corded by Messrs. Crampton and Goodissen. Dub. Hosp. Reports, vol. ii.

t As in the case of obliteration of the infeiior vena cava from the pressure of an aneurismal tumour observed by Reynaud. Journal Hebdom. de Med. vol. ii. p. 110.

16

ABDOMEN.

do well to note. M. Meniere* has described a case in which a very large vein, arising from the external iliac, passed up along the linea alba to the umbilicus, was continued along the obliterated umbilical vein, and opened into the vena portae. In another case, recorded by Manec, the vein originated in the same manner by two roots, reached the umbilicus, taking a course parallel to the umbilical artery, formed an arch outside the navel, and having re-entered the abdomen, opened into the vena portae. In another instance which occurred to Cruveilhier the superficial veins in the hypogastric region were enormously enlarged, at the umbilicus they ended in a trunk as large as a finger, which communicated with the vena cava as it passed under the liver.f Berard proposes to explain, by the supposition of the existence of such anomalies as those above described, the occurrence of fatal hemorrhages from wounds inflicted at the umbilicus, which have been attributed to the persistence of the um- bilical vein.J

c. The lymphatics. — Those on the anterior wall communicate above with the axillary glands, and below with those of the groin : the deep-seated lymphatics of the posterior wall communicate with the glands which lie along the lateral and anterior surfaces of the lumbar spine.

d. The nerves. — The nerves of the abdo- minal parietes are derived from the inferior intercostals and from branches of the lumbar plexus. The seventh, eighth, ninth, tenth, eleventh, and twelfth intercostal nerves termi- nate in supplying the transverse and oblique muscles and the recti ; the twelfth lies in front of the quadratus lumborum muscle, and gives several filaments to that muscle. The ilio- scrotal and inguino-cutaneous nerves are the branches of the lumbar plexus which mainly supply the inferior part of the oblique and transverse muscles. One branch of the genito- crural, which is found in the inguinal canal, also sends some twigs to these muscles.

The posterior wall is supplied by the sub- divisions of the posterior branches of the lumbar nerves.

Physiological action of the abdominal parietes and muscles. — We have already alluded to the peculiarity which distinguishes the abdominal cavity when compared with the other great cavities, namely, that its walls are in greatest part composed of contractile tissue. At first view the muscular apparatus of the abdomen would appear to be a great constrictor muscle destined principally to exert its influence on the cavity and its contents ; but when we take into account the attachments of those muscles

* Archives Gen. de Med. t. x. p. 381. The vascular distribution which existed in this subject presents, as Meniere has remarked, a striking simi- larity to that which is naturally found in the Saurian, Ophidian, and Batrachian reptiles, viz. a division of the general venous system which communicates with the hepatic vena portae.

t Velpeau, Anat. Chir. ed. 2. vol. ii. p. 32, and Mauec, Dissertation inaugurale. Paris, 1826.

$ Diet, de Med. art. Abdomen.

to the ribs, the vertebrae, and the pelvis, it becomes evident that they must likewise be destined to act upon the thoracic and pelvic cavities, as well as upon the vertebral column. In the constitution of the abdominal parietes we observe, as Berard* remarks, the most happy adaptation of structure to uses. A completely osseous covering would have greatly interfered with the functions of the abdominal organs, which are liable to experience changes both extensive and often very rapid, either by reason of the introduction of alimentary matter, whether solids or fluids, or by the disengage- ment of gases within the digestive tube, or by the progressive development of the impregnated uterus. We may moreover add that an exact repetition of the structure of the walls of the thorax would not have been well adapted to the abdomen for the same reason, namely, the too great resistance which it would afford to compression from within, thereby interfering with the distensibility of the enclosed viscera. The resistance, too, which a wall so constituted would afford to impulses from without could not have been so easily adapted to the impetus of the forces likely to act upon them as a purely muscular wall whose contractions and the intensity of them are obedient to the will.

The consideration of the action and uses of the abdominal muscles naturally comes under two heads : — 1 . their action upon the abdo- minal cavity and its contents ; 2. their influ- ence on the trunk generally, or parts of it.

It is the muscles that enter into the compo- sition of the anterior and lateral walls of the abdomen which act chiefly on the cavity and its contained viscera. The solidity of a con- siderable portion of the posterior wall, and the great strength of the lumbar muscles, give to that wall such a power of resistance as enables it to receive the compressed viscera without at all yielding. A reference simply to the attach- ments of the muscles of the anterior and lateral walls is sufficient to shew that these muscles when contracted must diminish the capacity of the abdomen, both in the lateral and antero- posterior directions ; and as the posterior wall is but little influenced, the viscera will be pushed partly upwards against the diaphragm, and partly downwards into the cavity of the pelvis, where their further descent is opposed by the levator ani. Hence it appears that a degree of antagonism exists between the diaphragm and the abdominal muscles, as well as also between those muscles and the levator ani. It is extremely difficult to maintain the abdominal muscles and the diaphragm at the same moment in a state of contrac- tion; in general they alternately yield the one to the other : and when it does happen that they are simultaneously contracted, the abdominal viscera must suffer an unusual de- gree of compression ; and it is not improbable that vomiting is sometimes produced by such a cause, and defecation, no doubt, is likewise aided by it. The danger of the protrusion of some of the hollow viscera between the fibres

* Loc. cit.

ABDOMEN.

17

of the muscles is provided against by the variation of direction in the fibres of the several layers; thus the fibres of the obliqui are in the directions of two intersecting diagonals, and those of the transversalis are different from both. By this arrangement a sort of network is formed, with meshes so small as to render a protrusion perfectly impossible in the healthy condition of the muscle. In the compression of the viscera the abdominal muscles are most completely congeneres, although the trans- versalis seems to be the best adapted to this action, and probably, for that reason, forms the layer which is placed nearest the peri- toneum. The recti muscles are powerful auxiliaries in affording a fixed point of attach- ment in front for the aponeuroses of the broad muscles, and the pyramidales assist in a similar manner by rendering tense the linea alba. Is this constant action of the abdominal parietes on the viscera necessary or favourable to the due performance of the functions of those organs, or to the continuance of the abdominal circulation? There certainly does not appear to be any evidence for the necessity of them for this purpose : that they are favour- able to it may be inferred from the fact that they do bear their present relation to them. We know from numerous experiments on animals, that both the transmission of the intestinal contents, and the abdominal circulation may go on when the abdominal muscles have been freely opened or removed. Hence we may answer this question with perfect justice in the words of Bichat : " The walls of the ab- domen favour these functions by their motions; but these motions are by no means essential to them."

It is in consequence of the power which the abdominal muscles thus appear to exert in compressing the viscera, that some physiolo- gists have attributed the act of vomiting to their action united with that of the diaphragm; and Magendie, reviving the opinions of Bayle, Chi- rac, and Shwartz,* went so far as to deny to the muscular coat of the stomach any partici- pation in this act, and to ascribe it wholly to the influence of the abdominal muscles. But Beclard, to whom the question was referred by the Academy of Medicine of Paris, proved satisfactorily that the abdominal muscles are active in producing vomiting when the sto- mach is distended in a certain degree, and that the muscular coat of the stomach is also active in emptying the contents of that viscus. This conclusion Haller had arrived at long ago, and clearly expresses it in the following passage : " Evidentissimum ergo videtur, vomitus qui- dem causam esse in ventriculo eumque in con- tractionem niti propriis vinbus atque aliquando vomitum perficere. Plerumque tamen irrita- tionem in ventriculo natam et sensum summse anxietatis, quse vomitum praecedunt, facere ut ad levandam aegrimoniam vires diaphragmatis 2t musculorum abdominis excitatae atque mo- lestiam de homine amoliturae, vomitum per-

* Vide Haller, Elementa Physiologiae, t. vi. sect. iv. § xiv. VOL. I.

ficiant. Unde neque a sola voluntate in pie- risque certe mortalibus vomitus cieri potest ncque a .sola absque voluntate natura — Quare recte conjunctas vires ventriculi et or^anorum respirationis Cl. Viri fecerunt. Et videtur dia- phragmaet abdomen plusvirium habere,quando ventriculus aut cibis repletus est, aut clausis ostiis distentus : tune enim magis ad perpen- diculum proximum ventriculum comprimunt et tota contingunt."*

If it be admitted that the abdominal muscles are active in producing vomiting, and in defe- cation and micturition, it will follow likewise that they must assist in parturition. While these pages were preparing for press, the fol- lowing passage presented itself to me, in an able arid interesting review of M. Velpeau's Treatise on Midwifery. It so fully illustrates the part which the abdominal muscles take in promoting parturition, that I venture to tran- scribe it, " It is certain," says the reviewer, " that a woman who ' bears down ' as it is termed, with all her force, who makes the most of her pains, however feeble they may be, will thus accelerate her delivery ; and that another may more or less delay delivery by voluntarily opposing muscular action as much as she can. For example; — a woman was admitted for de- livery at M. Baudelocque's theatre ; labour went on regularly, and the pupils assembled. The dilatation of the cervix now slackened, and no progress was made during the whole night. The ileves were fatigued and retired ; the pains immediately returned, and dilatation again went on. The young men again entered ; the phenomena of labour again ceased. Baude- locque, suspecting the cause, gave a hint to the students to retire, but to be at hand and enter upon a given signal. The patient now began to * bear down,' and the head of the child was quickly at the vulva The spectators were once more brought to the scene of action, and the labour was speedily terminated; for it had now advanced too far to be suspended by any voluntary effort or moral alarm of the woman. "f The fixedness of the inferior attachment of the abdominal muscles to the pelvis, and the mobility of the ribs, to which they are attached superiorly, evidently indicate that these muscles are destined to act upon the thoracic cavity. The transversalis does not, from the direction of its fibres, admit of this action to any extent; that office, therefore, devolves chiefly on the obliqui and recti. When these last-named muscles act together, they must compress the inferior opening of the thorax, draw its inferior margin downwards and backwards, and, by the compression thus exerted on the abdominal vis- cera, push them upwards against the diaphragm, which muscle is thus made to ascend into the thorax, and that cavity is thereby diminished in its vertical and antero-posterior diameters, and also, though not so obviously, in its trans- verse. Hence the lungs become so compressed as to be adapted to the altered capacity of the

* Haller, ubi supra. See, also, Richerand, Physi- ologic par Berard, art. Digestion, $ xxiv. t Medical Quarterly Review for April, 1835. p. 100.

Itf

ABDOMEN.

thorax, and thus these muscles must be con- sidered as very important agents in the act of expiration. It must be observed, however, that in order that they may act on the chest with their full force, it is necessary that that cavity should have been previously in a state of full dilatation, for under such circumstances the fibres of the obliqui and recti are con- siderably stretched and their levers elongated.* It is in the excited states of expiration, cough- ing, sneezing, &c., that this action of these muscles is most obvious.

But it is in the motions of the trunk that the abdominal muscles are called most into play. In all the inflexions of the trunk, whe- ther the body be horizontal or erect, these muscles are main agents. When the body is recumbent on a horizontal plane, the recti are thrown into action when the individual attempts to raise up the thorax, the spine being thereby brought into the state of flexion. If the thorax be fixed, while the body is still supine, the action of the recti will draw the pelvis upwards and forwards, causing slight flexion of the spine, and slightly approximating the upper margin of the pelvis to the lower margin of the thorax. Although the recti muscles are the principal agents in thus flexing the spine, the obliqui co- operate with them very powerfully, and are especially useful in maintaining the due propor- tion between the middle and lateral regions of the abdomen. When the two obliqui of the same side act together, the direction of their force is, as with all oblique muscles whose fibres decussate, in the diagonal between their fibres; and, therefore, when the obliqui of op- posite sides act in unison, they very powerfully aid the recti in flexion of the spine, approx- imating the thorax and pelvis anteriorly. When the obliqui of one side act, they produce a lateral inflexion of the trunk to that side, — the middle and opposite region of the abdomen being in this position rendered prominent by the viscera pushed over from the side of the contracted muscles. In what have been called the rotatory motions of the trunk, the obliqui muscles of the same side antagonize each other; thus in that movement by which the anterior surface of the trunk is made to look to the left side, the obliquus externus of the right side will co-operate with the obliquus internus of the left, but the obliquus internus of the right will antagonize the external muscle of the same side. " These muscles," (obliqui externi et in- terni,) says Dr. Barclay, " from occupying the whole of the lateral aspects extending be- tween the ilia and ribs, and from acting at the greatest lateral distance from the centre of motion, must always be muscles principally concerned in producing inflexions dextrad and sinistrad on the lumbar vertebrae, principal di- rectors in all the inflexions sternad and dorsad ; and, from the assistance which they give to the recti, principal librators also of the trunk, whe- ther we be sitting, standing, or walking."

The reciprocal action of the recti and ob- liqui on each other is one of the most beauti-

* Barclay on Muscular Motion, p. 522.

ful parts of the mechanism of the abdominal muscles. This is mainly to be attributed to the close connection which subsists between these muscles in consequence of the formation of the sheaths of the recti by their aponeuroses, and the adhesion of the anterior wall of those sheaths to the tendinous intersections of the recti. When the recti contract, the antero-pos- terior diameter of the abdomen is diminished, and consequently the viscera are pushed to- wards the sides ; when, on the other hand, the obliqui contract, they diminish the transverse diameter of the abdomen, and push the viscera forward in the middle line. In the one case, then, it will be evident that the obliqui act as moderators to the recti, and in the other the resistance of the recti moderates the action of obliqui, — the former muscles being, as Cru- veilhier remarks, as it were, two active pillars compressing forcibly the viscera against the an- terior surface of the spine. It is probably to enable the recti to act more completely as moderators upon the several segments of the obliqui that they are intersected by tendinous lines, with which theaponeurosesof those muscles are connected. Another use has been assigned to these intersections by Berlin, viz., — to multi- ply the points of attachment of the obliqui muscles, and to associate them, in many ac- tions, with the recti muscles. This is explained by a reference to the action of the recti in flex- ing the pelvis: were these muscles uncon- nected with the obliqui, they would act only on the pelvis, into which they are inserted ; but in consequence of the insertion of the internal oblique into the intersections of the recti, and the attachment of that muscle also to the crista ilii, the force of contraction of the recti is com- municated not only to the pubis, but also through the fibres of the obliquus internus to the rest of the pelvic margin.*

The action of the pyramidales seems to be chiefly on the linea alba, which they render, tense ; thus limiting the separation of the recti, and opposing the tendency to visceral protru- sion. Fallopius supposed that they acted on the bladder, especially when it was in a dis- tended state ; and Parsons conjectured that they might depress the suspensory ligament of the bladder (the urachus), and thus facilitate the contraction of that organ.

The other muscles which are from situation abdominal muscles in consequence of their connexion with the posterior wall of the abdo- men, are chiefly agents in the extension of the vertebral column : in their contracted state, however, they form a tense and resisting sur- face, against which the viscera are compressed by the contraction of the anterior muscles.

II. Of the Abdominal Cavity. — The annexed engraving (Jig. 5.) exhibits a view of the abdo- minal cavity, the anterior and part of the lateral walls having been cut away and the viscera removed. The subject is so bent backwards as to render the bodies of the vertebras very

* Berard, loc. cit., et Berlin, sur 1'usage de» enervations des muscles droits du bas-ventre, in . de 1'Acad. des Sciences de Paris.

ABDOMEN.

(Fig. 5.)

prominent anteriorly, and the continuity of the abdominal and pelvic cavities is thus clearly shewn. It is useful to examine the relations of the axes of these two cavities ; that of the pelvis passes forwards and upwards towards the umbilicus, while the axis of the abdomen passes from above downwards and forwards so as to terminate a little above the pubis, the two axes accordingly would intersect each other a little below the umbilicus at an obtuse angle. This angle may be obliterated by bringing the pelvis very much forward and producing a full flexion of the spine, and hence in all efforts for expulsion that attitude is almost instinctively assumed which shall identify the axes of the two cavities, and thus direct the efforts in the most favourable manner. The ordinary form of the cavity in the adult male is oval, but it presents some slight differences in the female and in the fetus ; and these differ- ences are dependent on the great or incomplete development of the pelvis. In the female the abdomen is generally more capacious than in the male ; and this greater size is more remark- able at the inferior part of it in the hypogastric region. In fact in the male it would seem that the great extremity of the oval is toward the thorax, and its smaller one towards the pelvis ; but in the female it is just the reverse, the larger extremity being toward the pelvis. It should be observed, however, that the modern

fashion of tightly compressing the lower part of the thorax has a material effect on the external characters of the female abdomen, otherwise there is no reason that the superior part of it should be proportionally less than in the male. In the foetus the abdomen is proportionally larger than at any other period of life : this is to be attributed to the imperfect development of the pelvis, and likewise to the great size which some of the abdominal viscera possess ; and as some time must elapse before the pelvis reaches its full dimensions, or the viscera lose their superfluous parts, the abdomen continues of this large size for a long period after birth.

The subdivision of the abdomen into regions is especially useful in reference to the contents of the abdominal cavity, which it is highly de- sirable the student should examine, so as to be able to assign to each compartment its appro- priate contents. The abdominal viscera may be subdivided into the membranous and the parenchymatous ; the former being such as the stomach and intestinal canal, the latter, such as the liver, spleen, pancreas, &c. The viscera have likewise been distinguished in reference to their position with respect to the peritoneum, by the names intra-peritoneal and extra-peri- toneal ; but it is sufficient to know that no serous membrane contains any organ within it (i. e. within its sac) to see the error of such a distinction. But we cannot adopt a better di- vision of the abdominal viscera than that which has reference to the functions of those organs, and which Beclard has adopted : viz. 1 . the organs of digestion — the stomach, the intes- tinal canal, the liver and its appendages, the spleen, and the pancreas : 2. the urinary organs — the kidneys and the ureters, to which may be added from their close relation to the kid- neys, the suprarenal capsules : 3. the organs of generation in the male — the vasa deferentia, and in the male foetus at the sixth or seventh month of intra-uterine life, the testicles ; none of the organs of generation can strictly be said to be abdominal organs in the female. In both male and female the other internal generative organs are pelvic viscera. If we add to the above enumeration of parts the abdominal por- tion of the aorta, its primary subdivision into the common iliacs ; the anterior subdivision of these arteries under the name of external iliacs ; the branches of the aorta which are distributed to the viscera as well as to the walls of the abdomen ; the common and external iliac veins; the vena cava ascendens ; the system of the vena portae ; the abdominal portion of the sympa- thetic system of nerves, both that which follows the arterial ramifications, and that which is the continuation of the chain of ganglia that lies along the spine, the termination of the par vagum ; the mesenteric glands, and the lacteals ; the lymphatics and their ganglia which lie along the spine; the origin of the thoracic duct, a portion of the course of that duct ;— these wil I complete the list of parts contained in the abdo- minal cavity.

The full particulars of the relative positions of the contents of the abdomen, and the abnormal

c 2

20

ABSORPTION.

states of that cavity, both congenital and mor- bid, including also the abnormal states of its parietes, we prefer to bring together in a sepa- rate article under the head CAVITY ABDO- MINAL, to which we beg to refer the reader. The special anatomy, both natural and ab- normal, of the several abdominal viscera is distributed among the articles INTESTINAL CANAL, KIDNEY, LIVER, PANCREAS, SPLEEN, SUPRARENAL CAPSULE.

BIBLIOGRAPHY. — The several systematic writers, as Winslow, Boyer, Portal, Bichat, Meckel, Cloquet, Marjolin, Hildebrandt, &c. for the titles of whose respective works seethe Bibliography of ANATOMY, (Introduction, ) — Velpeau, Anat. Chirurgicale. Paris, 1833. t. ii. Blandin, Anat. Topographique. Cru- veilhier, Dictionnaire de Med. et Chirurg. art. Abdo- men. Beclard et Berard, Diet, de Medecine. Ed. 2d. art. Abdomen. Pierer Anatomisch- Physiologisches Realworterbuch. herausgegeben von J. F. Pierer. Leipzig, 1816. art. Abdominal- muskeln. Gerdy, Anat. des formes exterieures. Paris, 1829. p. 122 and 199. Cloquet, Recherches Anat. sur les Hernies de 1'Abdomen, or the trans- lation by McWhinnie. Lond. 1835. Scarpa, on Hernia, by Wishart. Lawrence on ditto. Todd, on ditto. Dub. Hosp. Reports, vol. i. Flood's plates of Inguinal and Femoral Hernia. Lond. 1834. Cam- per, Icones Herniarum. Guthrie, on Inguinal and Femoral Hernia. A. Cooper, on ditto, and on the Testicle. Munec, Dissertation Inaugurale sur 1'Her- nie.1826. Colles's Surgical Anatomy. Dublin, 1811. Barclay on Muscular Motion, p. 337 et sqq.

( R. B. Todd.)

ABSORPTION in physiology (from ab- sorbeo : Lat. absorptio, Fr. absorption, Ger. die einsaugung, Ital. assorbimento.} The term absorption is employed in physiology to de- signate a vital organic function, the primary or immediate object of which is to furnish the system with a due supply of matter for its growth and subsistence. It is proposed, in the following article, first, to give an account of the organs by which the function is performed ; this will lead us, 2dly, to consider the question of venous absorption ; in the third place, we shall inquire into the mode in which the ab- sorbents act ; and, lastly, we shall offer some remarks upon the specific uses of the different parts of the absorbent system, and upon the re- lation which it bears to the other vital functions.

§. 1 . Description of the Absorbent System. — We propose, in the first instance, to restrict the term absorbent system to those organs, which are supposed to be exclusively appropriated to the function of absorption ; these may be in- cluded under the two heads of vessels and glands, the vessels being again subdivided into the lacteals and the lymphatics.

Although the absorbents are distributed to al- most every part of the body, and perform so im- portant an office in the animal economy, they were among the organs which were the latest in being discovered by anatomists. There are, indeed, some passages in the writings of Galen,* which would lead us to suppose that certain

* De Anat. Admin, lib. 7, sub finem ; De usu partium, lib. 4. cap. 19 ; An sanguis in arteriis &c. cap. 5.

parts of the absorbents had been seen by Erasistratus and Herophilus, as well as by himself; but it appears that they were, all of them, unacquainted with the relation which these vessels bore to the other organs, and were entirely ignorant of their office and destination. These scanty observations of the ancients seem to have been entirely neglected, or even for- gotten, until the study of anatomy was revived, together with that of the other medical sciences, in the sixteenth century. In the course of the researches which were then made into the structure of the animal body, various parts of the absorbent system appear to have been brought into view, and are noticed, among other writers, by Fallopio,* who discovered the lym- phatics, connected with some of the abdominal viscera, and by Eustachio,f who detected the thoracic duct. But although their descriptions, especially that of Eustachio, are sufficiently correct to enable us to identify them, as forming a part of the absorbent vessels, yet they were unacquainted with their specific nature and office, and with their relation to the sangui- ferous system.

It is generally admitted that the merit of the discovery of the lacteals is due to Aselli ; this discovery he made in the year 1622. While he was examining the abdominal viscera of a dog, he observed a series of vessels attached to the mesentery, which appeared to have no direct connexion with the arteries or veins, and which, from the circumstance of their con- taining a white opake fluid, he denominated Lacteals.]:

He regarded them as a distinct set of vessels, exercising a specific function, distinct from that of the sanguiferous system, and he as- certained that they took their origin from the surface of the intestines, and proceeded to- wards the more central parts of the body, but it was not until the year 1651, that their ter- mination in the thoracic duct was discovered by Pecquet. §

The discovery of the other species of ab- sorbent vessels, styled, from the appearance

* " Observ. de Venis," lib. 3., in Op. p. 532; first published in 1561. We may add the names of Fabricio, Piso, and Gassendi, who appear to have seen certain parts of the lymphatics, although they were not aware of their specific nature. See Bar- tholin, de Lact. Thor. c. 2 ; and Mascagni, Vas. Lymph. Hist. Proleg. sub init.

t De Vena sine pari, Antig. 13, sub finem, in Opusc. Anat. ; first published in 1564. See Haller, Bibl. Anat., p. 224 ; also Douglas, Bibliog. Anat., p. 99.

$ Dissertatio de Lactibus ; first published in 1627. See Bartholin, de Lact. Thor., c. 4 ; Sheldon on the Absorbent Syst., p. 20, 1. Aselli's work is ac- companied by plates of very rude execution, but sufficiently expressive of the object.

§ Exper. nova anat. ; first published in 1651 ; Bartholin, c. 5. In 1652, Van Home published the first plate of the thoracic duct. There is some reason to suppose that Vesling had an imperfect view of it previous to Pecquet ; he published his Syntagma Anat. in 1647. In describing the pancreas he speaks of the venae lacteae, lately discovered by Aselli, •which convey the chyle to the liver, and figures them in tab. 4. fig. 3.

ABSORPTION.

-21

of the fluid which they contain, the lymphatics, was posterior to that of the lacteals. The trans- parency of their contents rendered them less conspicuous and less easy of detection, so that, although certain parts of them appear to have been seen by Fallopio, and afterwards by Aselli and others, yet it was not until the year 1650, that they were distinctly recognized, and their connexions ascertained. The discovery of the lymphatic system was the subject of a warm controversy between Bartholin and Rud- bek, on the merits of which we are, after so long an interval, scarcely able to decide. It appears, however, to have been the opinion of Haller, and the most distinguished anatomists of the last century, that the lymphatics were detected, in the first instance, by Rudbek ; that Bartholin had some intimation of the dis- covery, that he then took up the subject, and pursued it much farther than it had been done by Rudbek.*

There is a third individual, on whose behalf a claim of priority has been made, which pos- sesses at least considerable plausibility. We are informed by Glisson, that an English ana- tomist of the name of JolifTe distinctly re- cognized and exhibited the lymphatics of many of the abdominal viscera, previously to the alledged discovery of either Rudbek or Bar- tholin.f But even if we allow Joliflfe the full merit both of discovering these vessels, and being aware of their specific nature, it does not appear that he published his discovery, so that it will scarcely affect the rival claims of the former anatomists. The discovery of the ab- sorbent or conglobate glands, as they have been termed, was made, for the most part, at the same time with that of the vessels, as a ne- cessary consequence of the intimate connexion which subsists between them.

After the existence of the lacteals had been clearly announced by Aselli, and of the lym- phatics by Rudbek and Bartholin, the atten- tion of anatomists was very generally directed to these organs, and discoveries were suc- cessively made, by various individuals, of the presence of the latter in almost every part of the body, and in connexion with almost every one of its organs. The labours of William and John Hunter, of Monro sec , arid of Hewson, were among the most important in their re- sults, while we are indebted to Cruikshank, and still more to Mascagni, for their minute descriptions and accurate representations of the absorbent system, in all its parts, and with its various relations and connexions.]:

* El. Phys., ii. 3. 1; BiV.l. Anat., t. i. §.378 and 415; and Not. 4. ad §. 121. Boer. Prsel. Bartholin's statement of his claim is contained in his " Anat. Reform." p. 621, 2 ; see also his trea- tise, " Vas. Lymph. Hist. Nov." and Rudbek's *' Nova Exerc. Anat." For the historical part of the subject we may refer to Mascagni, Prolegomena, and to Meckel, Manuel d'Anat. par Jourdan et Breschet, t. i. ch. 2. p. 179 . . 202.

t Anat. Hepat. c. 31. See Haller, Bibl. Anat., t. i. p. 452 ; also Mascagni, Prolegomena.

t For the most original and correct desciiption of the lacteals, the reader is referred to Haller, El. Phys. xxv. 1. 4 . . 8 j Mascagni, Vas. Lymph. Corp.

With respect to the minute anatomy of the lacteals, we are informed that they originate from certain small projecting bodies, termed villi, which are attached to the interior surface of the intestines, styled from this circumstance the villous coat. These villi are described as consisting of a number of capillary tubes, which terminate with open mouths, and that by the union of these tubes the branches of the lacteals are composed, which are suffi- ciently large to be visible to the eye. We must remark, however, that although these villi, as constituting the mouths of the lacteals, have been minutely described, and even figures given of the appearance which they exhibit in the microscope, yet that considerable doubt is still entertained of their existence, and that they are even entirely discredited by some anatomists of the first eminence.* Upon the whole we may conclude that the opinion, which has been generally adopted, respecting the capillary termination of the lacteals, is somewhat theo- retical, rather derived from the supposed ne- cessity of such a formation to cany on the functions of the vessels, than from any actual observations that have been made upon them.

When the lacteals have acquired sufficient magnitude to become visible to the eye, they are seen to proceed along the mesentery, the small vessels running together to form large branches, and these again forming others that are still larger, until the whole of them unite into a few main trunks, which terminate in the receptacle at the lower extremity of the thoracic duct. During their progress, the small vessels

Hist., p. 1. $. 7. art. 8. tab. 1. fig. 7; Sheldon,~on the Absorb. Syst. ch. 2. pi. 3, 4, 5 ; Santorini, Tabulae, No. 13. fig. 3 ; Magendie, Physiol. t. ii. p. 158 . . 0. The translation of Mascagni 's work, with copious notes by Bellini, may be advantageously consulted ; it is not accompanied by plates. For the lymphatics we may refer to Haller, ii. 3. 2 ; Meckel, Diss. Epist. de Vasis Lymphaticis ; Hew- son, Enq., ch. 3. pi. 3, 6 ; Mascagni, ps. 1. sect. 7. tab. 4 et seq. ; Cruikshank, on the Absorb., p. 148 et seq. ; Soemmering, Corp. Hum. Fabr. t. v. p. 388 et seq. ; many of Mascagni's plates are transferred into Cloquet's valuable " Manuel." Art. " Inhalation," par Rullier, in Diet, des Sc. Med. t. xxv. 3. Art. " Lymphatique," par Chaussier et Adelon, ibid, t. xxix. p. 249, 260 ; Meckel, Manuel, sect. 6. ch. 2; Quain's Elem. of Anat. p. 560 . . 574. In Elliotson's Physiol. ch. 9. p. 140 . . 2, we have a " short account of the first discovery of the absorbent system." Scemmer- ing's treatise, De Morbis Vasorum Absorb, con- tains a most ample and learned catalogue of the various works on absorption, from the earliest period to the date of its publication in 1795.

* See Lieberkuhn, Diss. de Fabr. Vill. Intest. passim, cum tab. 1, 2; Hewson's Enq., c. 12, pt. 2 ; Cruikshank's letter to Clare, p. 32 . . 4 ; Shel- don on the Absor. Sys., p. 32 . . 8, tab. 1, 2 ; Hedwig, Disq. Ampull. In opposition to these and other authorities, on the affirmative side of the question, we have the strong negative evidence of Mascagni, whose plates do not sanction the description of Lieberkuhn, tab. 1. fig. 1. 3 ; and tab. 3. fig. 1,2,3, 5; and the decided opinion of Magendie, Journ. de Physiol. t. i. p. 3 et alibi. On this sub- ject see the remarks of Haller, not. 9. ad §. 91. Boerhaave, Prael. et not. 4. ad §. 103. The ob- servations of Du Vernoi, Mem. Petrop. t. i. p. 262 ec seq., seem scarcely to have been confirmed.

22

ABSORPTION.

frequently anastomose with each other, so as, in many instances, to form a complete network or plexus, in which respect their course differs from that of the veins, where the small branches unite to form the larger ones, without the lateral communications.

The lacteals are furnished with numerous valves, which are disposed in pairs, and have their convex surface turned towards the intes- tine,* so that, in the ord.nary and healthy con- dition of the vessels, their contents are pre- vented from retrograding, and necessarily pro- ceed from the small branches to the larger trunks. The coats of the lacteals are thin and transparent, and hence it is that these vessels, except when they are filled with chyle, are so difficult of detection. They seem, however, notwithstanding the apparent delicacy of their texture, to be possessed of considerable strength, and to bear being distended far be- yond their ordinary dimensions without being ruptured. When they are completely filled with chyle, and still more, when they are for- cibly distended by injections, the number of valves which they possess gives them a jointed or knotted appearance, and it seems to have been this circumstance, together with the white colour of their contents, which first attracted the notice of anatomists, and led to their dis- covery. With respect to their structure, besides the peritoneal covering which they possess in common with all the abdominal viscera, they seem to be composed of two distinct parts, an internal membrane, which by its duplicature forms the valves, and an external membrane, which constitutes the main substance of the vessel.

To these two obvious component parts many authors have added a muscular coat, and some anatomists of great respectability assert that they have actually detected transverse fibres, in which their contractile power is supposed to reside. Other anatomists, however, of equal authority, deny the existence of this muscular coat, and, it must be acknowledged, that the weight of the negative evidence seems to pre- ponderate. But we may remark, on the other hand, that although these transverse fibres, constituting the muscular coat, in consequence of their transparency, or from some other cause, have hitherto eluded our observation, so that we have no positive proof of their existence, the lacteals certainly exhibit what appears to be very decided marks of contracti- lity, and as they are not immediately con- nected with any organ equivalent to the heart, there seems to be no means, except their own contractility, by which their contents can be propelled-! See CHYLIFEROUS SYSTEM; LAC-

* These were very minutely examined by Ruysch, Dilucid. Valvul., op. t. i, p. 1 . . 13 ; they are ac- curately described by Sheldon, p. 28.

t Mascagni, ps. i. sect. 4. p, 26, informs us that he could not detect the fibres; Cruikshank, on the contrary, conceives that he has seen them in the thoracic duct, p. 61 et alibi ; and Sheldon speaks of the muscular coat as sufficiently obvious, p. 26. Meckel, Manuel, (. i. p. 185, does not admit their sxistence ; and this is the case with Chaussier and

The anatomical structure of the lymphatics seems to be essentially similar to that of the lacteals ; they are composed of a firm elastic membranous substance, capable of consider- able distention without being ruptured, and furnished with numerous valves ; like the lac- teals they form very frequent anastomoses. We have the same evidence of their contracti- lity as of that of the lacteals, although we are perhaps still less able to demonstrate the actual existence of their muscular fibres. We presume that they are likewise analogous to the lacteals in the nature of their office, and in their desti- nation, although they differ from them with respect to their situation, or the parts of the body to which they are attached ; the lacteals being confined to the membranes connected with the intestines, while the lymphatics are found in almost every part of the body, and connected with nearly all its various textures.* They differ also in the nature of the fluid which they contain, for while that of the lac- teals, as has been stated above, is white and opaque, the fluid found in the lymphatics is transparent and colourless, so as to resemble water, from which they have derived their spe- cific denomination.

It is very difficult, if not impossible, to trace the actual commencement of the lymphatics ; but partly from anatomical researches, and partly from physiological considerations, we are led to conclude that they originate from the various surfaces of the body, of all de- scriptions, both internal and external. They resemble the lacteals, in passing from larger to smaller branches, which, after numerous anastomoses, unite in a few large trunks, the greatest part of which terminate in the thoracic duct. The great trunks of the lymphatics are, for the most part, arranged into two distinct series, one considerably more superficial than the other; it is observed that they generally follow the course of the great veins, but it may be doubted whether any direct communication

Adelon, " Lymphatique,"Dict. des Sc. Med. t.xxix. p. 256. Breschet, art. " Lymphatique Systeme," Diet, de Med. t. xiii. p. 389, considers it doubtful. Some curious observations were made by Desge- nettes, on the action of the absorbents after the apparent death of the system, Journ. Med. t. Ixxxiv. p. 499 et seq. Similar observations were after- wards made by Valentin, t. Ixxxvi. p. 231, et seq. ; this action was not, however, supposed to depend on contractility. Wrisberg informs us that he has frequently seen spasmodic contractions in the large vessels a'nd in the thoracic duct, Observ. Anat. Med. de Vas. Abs. Morb. in Comment. Soc. Reg. Gotting. v. ix. § 19. p. 149.

* For the extent of the lymphatic system, see Haller, El. Phys. ii. 3. 4, and the later account of M. Magendie, Physiol. t. ii. p. 174, and Jour, t. i. p. 3, who conceives that absorbent vessels have not been detected in the brain, the spine, and the organs of sense. Dr. Alison likewise conceives that they have not been detected in the cranium or ner- vous system, Outlines of Physiol. p. 76. Mas- cagni, however, appears to have detected a few small lymphatics in the brain, tab. 27. fig. 1. Monro secundus argues in favour of their existence, but it does not appear that he actually detected them in any part of the nervous system ; on the Nervous System, ch. v. sect 1. and Three Treatises, ch. 4, 5.

ABSORPTION.

23

exists between them during their course, and we are not aware of any physiological cause of this arrangement.

With respect to the mouths or origin of the lymphatics there is even more uncertainty than with respect to that of the lacteals ; no anato- mical investigation has hitherto been able to detect them, and although numerous facts of constant occurrence would seem to prove that their capillary extremities are distributed over all the surfaces of the body, it is from various pathological observations and from the analogy of the lacteals that we arrive at this conclu- sion.*

The thoracic duct is a vessel of considerable size, which is situated near the spine, and which extends from about the middle of the dorsal vertebrae to a short distance above the left subclavian vein ; here it assumes an arched form, and is bent down until it enters the vessel near its junction with the jugular vein of the same side.f The duct, in its passage along the spine, is deflected in various ways, and proceeds in a somewhat irregular or tortuous course. For the most part it consists of a single trunk, but occasionally there are two trunks, either of the same or of different sizes, and we have not unfrequently partial appen- dages, which are added to the main trunk in different parts of its course.]: Besides what is properly considered as the thoracic duct, in which all the lacteals and the greatest part of the lymphatics terminate, a portion of these latter, especially those which proceed from the upper part of the body and from the superior extremity of the right side, are generally col- lected into a separate trunk, named the great right lymphatic vessel, or right thoracic duct, which is connected with the right subclaviau vein.§ These irregularities in the disposition and form of the thoracic duct may be consi- dered as in no respect affecting its physiological uses, and to be no more than an anatomical variation of structure, probably depending

* See Magcndie, Physiol. t. ii. p. 175 Watson, however, conceived that he had detected their open mouths on the surface of the bladder, Phil. Trans, for 1769, pi. 16. Monro, in speaking of the lym- phatics of fishes, remarks that there is " no doubt that they begin by open mouths," p. 30.

t For descriptions and plates of the thoracic duct the following works may be referred to; Haller, Prim. Lin. c. xxv. § 565; Op. Min. t. i. p. 586 et seq. tab. 11, 12 ; and El. Phys. xxv. 1. 10 . . 3 : Albinus, Tab. Vas. Chylif. ; Holius and Saltzmann, in Haller, Disp. Anat. t. i. ; Cheselden, Anat. pi. 26; Portal, Mem. Acad. pour 1770; Sabatier, ibid, pour 1786 ; Haase, De Vas. Cut. et Intest. Abs. tab. 2. and tab. 3. fig. I ; Mascagni, ps. i. sect. 7. art. 8. tab. 13, 15, 19; Sheldon, pi. 5; Cruikshank, p. 166. . 176 ; Magendie, Physiol. t. ii. p. 160; Meckel, Manuel, § 1698.

J In Mascagni, tab. 15, we have an example of this irregularity.

§ This is said to have been discovered by Stenon in 1664 ; Meckel, Manuel, § 1703. See Haller, Prim. Lin. $ 766 and Hewson's Enq. pt. 2. p. 61 . . 3, pi. 4. Cruikshank, p. 176, 7, conceives that Hew- son was the first who described the lymphatics of the right side as being collected into one trunk. For the figure of this part, see Mascagni, tab. 19. nos. 185, 187.

upon some mechanical cause. It is, however, a circumstance of considerable importance in respect to the pathological conclusions that have been sometimes drawn from the obstruc- tions of this organ, as well as from the experi- ments that have been performed upon it.* The structure and properties of the thoracic duct appear to be similar to those of the large trunks of the lacteals and lymphatics; its coats are comparatively thin and transparent, yet it is possessed of considerable strength, and is ca- pable of being distended much beyond its ordinary bulk ; it is furnished with numerous valves, and exhibits a great degree of con- tractility.

The lymphatic or conglobate glandsf com- pose a very important part of the absorbent system, if we may judge from their number and their general diffusion over every part of the body. They are of various sizes, and are grouped together in various ways; occasionally they are single, but more frequently connected together in masses of considerable extent. They are found in almost every part of the body, always connected with the lacteals and lympha- tics, and it is asserted that each one of these ves- sels, in some part of its course, passes through or is connected with one or more of these glands.}; There are certain parts of the body in which they are more numerous, and are connected in larger masses ; the lacteals are furnished with numerous glands in their passage along the mesentery, while the glands that belong to the lymphatics are found in the greatest number and largest masses in the groin, the axilla, and the neck. It is necessary to remark that this account of the distribution of the lymphatic glands applies only to the animals which belong to the class of the mammalia; in birds they are much more rare, and still more so in fish, while among the lower animals, where we have suffi- cient evidence of the existence of an absorbent system, the glands have not yet been satisfac- torily demonstrated .§

With respect to the structure of these glands, as well as that of glands of other descriptions, a controversy has long existed among anato- mists, whether they consist of a series of cells or follicles, as they have been termed, or whe- ther they are composed simply of a congeries of vessels. The question may be regarded as still at issue ; but it may be remarked that whereas the older anatomists generally leaned to the opinion of the follicular structure of the

* See on this subject Sir A. Cooper, in Med. Rec. and Res. p. 86 ct seq., and Magendie, Journ. t. i. p. 21.

t Some ot the late French physiologists prefer the term lymphatic ganglions, upon the principle that the term gland more properly belongs to an organ of secretion.

$ Mascagni, ps. 1. sect. 4. p. 25 : but this h<* been doubted by some anatomists; see Hewson, pt.2. p. 44. 5.

$ See Fleming's Zool. t. i. p. 338 ; Blumenbarh's Coimp. Anat. by Lawrence, ch. xiii. p. 256 ; Diet, des Sc. Med. art. <« Lymphatique," par Chnussier et Adelon, p. 249; Breschct, art. " Lymph. Syst.," Diet, de Mod. t. xiii. p. 397. Hewson in- forms us that birds have lymphatic glands in the

24

ABSORPTION.

glands,* the moderns have more frequently adopted the hypothesis of their vascular texture, so that we may consider this doctrine as sup- ported by the most recent and elaborate re- searches, f See LYMPHATIC; GLAND.

§ 2. The guest ion of venous absorption con- sidered.— We have now been describing those organs, which are more specifically or appro- priately termed the absorbent system, as being those parts the office of which is confined to this operation. But a very important and in- teresting question must now be discussed, whether the function of absorption is exclusive- ly performed by the lacteals and the lymphatics.

The ancient anatomists and physiologists being unacquainted with the existence of the lacteals and the lymphatics, yet observing the evident effect of the operation of absorption, ascribed these effects to the action of the veins; and among the moderns, for some time after the discovery of what were more appropriately termed the absorbent vessels, it was still sup- posed that the veins co-operated with them, and in some cases were even the principal agents. This was the universal doctrine until the middle of the last century, and was one of the points which was decidedly maintained by Haller and his disciples.^

The arguments by which the hypothesis of venous absorption was supported may be re- duced to two classes, partly of a physiological and pathological, and partly of an anatomical nature; the first consisting of the results of experiments performed for the express purpose of investigating the subject, and of considera- tions derived from the morbid conditions of the system ; the second depending more exclu- sively upon anatomical considerations. The

neck, but that they are not found connected with the absorbents of the abdomen, and that they are en- tirely wanting in fish and in the amphibia ; Phil. Trans, for 1768, p. 217 et seq., and Enquiries, pt. ii. ch. 4, 5, 6. We have the same statement made by Monro. with respect to fish, p. 31. An- tommarchi, on the contrary, asserts that birds, fish, reptiles, and amphibia have " pochissime glan- dule ;" Prod, delle grande anat. di Mascagni, p. 8^ but the statement is made in a general way, and without reference to any particular observations. It would appear that no specific apparatus for ab- sorption has been discovered in any of the inverte- brated animals.

* We have the authority of Nuck, in favour of the cellular structure, Adenologia, c. ii. p. 30 et seq., fig. 9 . . 12 ; also of Cruikshank, c. 14 ; and of Abernethy, Phil. Trans, for 1776, p. 27 et seq.

t See Hewson, v. iii. c. 2. pi. 2; Werner and Feller, Vas. Lact. and Lymph. Descript. tab. 2; their figures, however, appear to be exaggerated ; Beclard, add. a Bichat, p. 231 ; Monro tert., Elem. v. i. p. 558. On the lymphatic glands generally see Haller, El. Phys. ii. 3. 16. .27 ; Beyer, Anat. t. iii. p. 243 . . 257 ; Mascagni, ps. i. sect. 5. p. 31 ; Rnliier, ubi supra, p. 120 et seq. ; Breschet, ubi supra, p. 394. For plates of the glands, see Mas- ca<mi, tab. 1 . fig. 8 ... 12, tab. 2. fig. 4 . . 8, tab. 4. fig. 2. tab. 8, 16, 26; Cruikshank, pi. 3; Sheldon, tab. 3, 5.

| Boerhaave, Praelect. § 103. and $ 247 ; Haller, in not, 1. ad § 106, Boerhaave, Praelect., and not. 1. ad § 245 ; also El. Phys. ii. 1. 28 ; Monro secun- dus, De Ven. Lymph., p. 14 . . 21 ; Walter, sur la Resorption, Nouv, Mem. Berlin, pour 1786 . .7, § 15 et seq. ; Magendie, Physiol. t. ii. p. 238.

experiments referred to consisted in passing injections from the veins to the absorbents, or the reverse, thus proving, as was supposed, that a direct connexion subsisted between these vessels. They were performed by the most skilful anatomists of the age, and were gene- rally acquiesced in, without either the accuracy with which they were conducted, or that of the conclusions deduced from them, being ever called in question. Another class of experi- ments consisted in passing ligatures round the thoracic duct, so as to render it impervious to the passage of the chyle, when it was supposed that under these circumstances the nutrition of the animal was not interrupted,* and the same conclusion appeared to be substantiated by various cases of natural obstruction of the duct, or by certain malformations of the part, where it was either defective, or did not convey its contents, in the ordinary manner, into the veins. The other set of arguments, which are more purely anatomical, were derived from the supposed fact that various parts of the body, which were evidently subject to the operation of absorption, were without lymphatics, and that this was likewise the case with large classes of animals, the general structure of which, as far as regards their growth and nutrition, was analogous to that of the mammalia. Admitting these data, it seemed to be a necessary conse- quence that absorption must in these instances be performed by the veins, and hence it was inferred that in all classes of animals, and in all parts of the body, the veins co-operated with the lacteals and the lymphatics in the function of absorption.

The doctrine of venous absorption was first formally called in question, nearly at the same time,f by Wm. Hunter and by Monro se- cundus,J who, as it would appear, to a certain extent, entered upon the investigation inde- pendently of each other. The priority of dis- covery in this, as in so many points connected with anatomy, was for a long time the subject of warm controversy. We may remark con- cerning this question, that if the judgment of Ihe present age should incline to ascribe to Hunter the original conception of the hypo- thesis, it is also disposed to allow to Monro the merit of establishing his opinion by a skilful and laborious process of experiment and observation.

The method which these illustrious rivals adopted was, first, to repeat the experiments of their predecessors, when, by noticing with scrupulous accuracy all the circumstances con- nected with them, they were able to demon- strate, or at least to render it highly probable, that in all those cases where injections had passed between the absorbents and the veins, either rupture or extravasation had taken place, and that, when this was carefully guarded

* Some experiments of this kind are referred to by M. Majendie, as having been performed by M. Dupuytren, Physiol. t. ii. p. 167. See also Ri- cherand, Elemens de Physiologie par Berard.

t Medical Comment., passim ; Cruikshank, In- trod.; Walter, § 10 et seq.

J Dissert, de Sem. rt Test, in Smellie, Thes. t. ii. and De Ven. Lymph. Valv.

ABSORPTION.

25

against, the supposed connexion between the two sets of vessels could not be demonstrated.* In those experiments, where the thoracic duct had been artificially obstructed, or in the cases where the same thing had occurred as the result of disease or malformation, they were enabled to detect some supplementary vessels or some imlirret channel, by means of which the chyle had been conveyed to the veins.

With respect to the parts of the body, or to the animals of an inferior order, which were supposed not to be furnished with ab- sorbent vessels, by prosecuting their examina- tion with more care they gradually detected the existence of these vessels in many cases where they had not been previously known to exist; and they were discovered in so many new situations that it became a fair inference that every part of the body, and every animal whose structure is generally analogous to that of the mammalia, is provided with an appropriate apparatus of absorption, although, from the texture or the peculiar nature of the vessels, it may be very difficult actually to demonstrate their existence. In this train of 'investigation the labours of William Hunter and Monro were ab!y seconded by various anatomists, both in this country and on the continent, among whom we may select the distinguished names of John Hunter, Hewson,f Cruikshank, and Mascagni.

* We must, however, bear in mind that we have the high authority of Meckel in favour of the com- munication between the lymphatics and the veins ; " Sur Resorption," "Nouv. Mem. Acad. Berl. ann. 1770, p. 19 et seq.

The researches of some of the most accurate among the anatomists of the present day seem also to show that occasional communications exist be- tween some of the lymphatics and the contiguous veins; but this is a different kind of relation from that \vhich was contemplated by the older anatomists between the sanguiterous and the absorbent systems. This point is fully discussed by Fohmann, in his late work, '• Sur le commun. des vaiss. lymph, avec les veins," where we have an account of his own observations, as well as those of preceding anatomists ; he conceives that the observations of Lippi, of which an account is given in his " Illus- trazioni fisiol.", are not correct : see also the remarks of Antommarchi, Ann. Sc. Nat. t. xviii. p. 108, 9. The observations of Fohmann have been confirmed by Lauth, in his " Essai sur les Vaisseaux Lymph." We may here refer to the observations of Bleuland, which were made fifty years ago, on what he styles the arteriol;e lym- phaticae, by which a communication was supposed to be maintained between the sanguiferous and absorbent systems; see his " Experim. Anat." Panizza of Pavia also opposes the doctrine of Lippi ; Ossorvazioni, c. 3 and 5. Mr. Abernethy, in examining the vascular system of the whale, discovered certain communications between the sanguiferous and the lymphatic vessels ; but the nature of the connexion is perhaps a little doubtful ; Phil. Trans, for 1796, p. 27 et seq. For further information on this subject, see a lecture on the lymphatic system lately published by Dr. Graves. Mr. Kiernan, in his elaborate researches into the anatomy of the liver, gives it as his opinion that the doctrine of Lippi has been " satisfactorily con- futed " by Panizza ; Ph. Tr. 1833, p. 729. See Elliotson's Physiol. p. 128,9 ; s. 1. also a paper in Ann. Sc. Nat. t. 21. p. 252 et seq.

t Phil. Trans, for 1768 and 1769; in these vo-

The experiments of Hunter may deserve to be particularly noticed, because they consisted not merely in repeating and correcting those of preceding anatomists ; but, in addition to these, he entered upon a series of original researches, which are highly characteristic of that ingenuity and acuteness for which he was so eminently distinguished. The experiments essentially consisted in filling portions of the small intestines with a fluid, the sensible pro- perties of which might be easily recognized, and retaining it there so as to allow of its entering into the veins of the mesentery, were they capable of absorbing it ; the result, however, is stated to have been that in no instance could the fluid be detected in these veins. These experiments appeared to have been so carefully conducted, and so frequently repeated, as to have impressed the minds of anatomists and physiologists with a conviction that the lacteals were the only vessels which are concerned in the absorption of the chyle ; and although it was not possible to perform analogous experi- ments on the lymphatics, yet it seemed a natural inference, that we might extend to them the conclusion which had been established with respect to the lacteals.*

In proof of lymphatic absorption various facts were brought forward, which seemed clearly to show that when extraneous or noxious substances were introduced into the system, it was done by the medium of the lymphatic vessels rather than of the veins; and it was thence argued that, as these vessels perform the func- tion of absorption under certain circumstances, and that we are not acquainted with any other office which they serve in the system, we may conclude that they are the sole agents in the action of absorption. Although the argument, as applied to the lymphatics, was far less direct and conclusive than to the lacteals, yet the analogy between the two organs appeared so strong, and so many concurring circum- stances appeared to favour the doctrine, that it was very generally received, and may be considered as having been the established opinion at the conclusion of the last century .f This unanimity of opinion was, however, of very short duration; for anatomists had scarcely ceased to contend for the honour of the dis- covery of the exclusive action of the lacteals and the lymphatics in the function of absorp- tion, when the doctrine itself was impugned by physiologists of the first eminence, who supported their views by a powerful train of arguments, enforced by numerous experiments,

lumes are contained his account of the lymphatics of birds and fishes.

* Med. Comment, c. 5 p. 42 . . 8 ; Cruikshank, c. 5. p. 21.

t See the judicious summary of opinions in Mascagni, ps. i. sect. 2, 3 : and in Rullier, ubi supra, p. 136 et seq. The doctrine of venous ab- sorption was, however, still maintained by many intelligent anatomists, especially by the high au- thority of Meckel, De Fin. Ven. et Vas. Lymph. 1772 ; and of Walter, Sur la Resorption, ubi supra. See particularly his general conclusion, § 92 : he conceives that the veins are the only agents in the absorption which is carried on ut the surface and from the cavities of the body.

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ABSORPTION.

and by various pathological considerations. Of these authors, one of the first, both in point of time and of ability, is M. Magendie, whose opinions on this subject, connected as as they are with some of those of his most distinguished countrymen, have been brought forward in a form which entitles them to the fullest and most respectful attention.

Of the two sets of observations by which Hunter and Monro attempted to establish their hypothesis respecting lymphatic absorption, those derived from the analogy of the lacteals may still be considered as maintaining their ground ; while the conclusion which they de- duced from their experiments has been called in question, partly because it was thought not to be the legitimate inference from the experi- ments, and partly in consequence of the ex- periments themselves having been conceived to be imperfect or incorrect. It is principally upon the latter ground that the force of the objections has been rested ; and it has been, first, by repeating the experiments of Hunter, and afterwards by varying them in different ways, that their insufficency has been attempted to be proved. It has been stated above that the main support of the doctrine of the ex- clusive action of the lacteals and the lymphatics was derived from those experiments of Hunter, in which it appeared that, when the circum- stances were the most favourable for the re- ception of substances into the veins of the mesentery, they could not be proved to have entered these vessels ; and hence it was con- cluded that the veins did not, under any cir- cumstances, possess the power of absorption.

We are informed, however, by M. Magendie that experiments have been performed by him- self and by M. Flandrin, which afforded directly contrary results, and that these experiments were so frequently repeated, and varied in such a manner, as to leave no doubt of their accuracy.* We have here the opposing testi- mony of individuals, both of them of the highest authority in science, and eminent for their skill in experimental research. From personal considerations it might be difficult, if not impossible, to decide between them ; but when we take into account the circum- stance that the experiments of MM. Magendie and Flandrin were executed subsequently to those of Hunter, and with the benefit of his experience and that of the improved state of the science during the last half century ; when, moreover, we are informed that the experiments of the French physiologists were more nu- merous than those to which they were opposed, and that their results were uniform and un- equivocal, we can scarcely refuse our assent to the conclusion, that the experiments of John Hunter do not afford a sufficient foundation for the doctrine of the non-absorption of the veins.

But the French physiologists have not sa- tisfied themselves with repeating the experi- ments of Hunter; they have extended them

* Physiol. t. ii. p. 181 et seq. ; Journ. Med. t. Ixxxv. p. 372 et seq., and t. Ixxxvii. p. 221. et seq., and t. ex. p. 73 et seq.

in various ways, and have obtained results supposed to be still more decisive in favour of venous absorption. Among the most im- portant, or at least the most curious of these, is an experiment which was performed by M. Magendie, in conjunction with M. Delille, and which was conceived by these physiolo- gists to afford the most unequivocal proof of their hypothesis. It consisted in dividing all the parts of one of the posterior extremities of a living animal except the artery and the vein, and in applying to the foot a poisonous substance ; when, in the short space of a few minutes, the effects of the poison on the func- tions of the animal were most distinctly ap- parent.* It was argued that in this case there was no mode of communication by which the poison could be conveyed from the extremity to the centre of the system except the vein, and that, therefore, the vein must have acted as the absorbing vessel. The experiment was rendered more striking, and, as was conceived, more conclusive, by dividing the bloodvessels themselves and introducing metallic tubes between the divided ends, through which alone the two currents of the arterial and venous blood respectively could pass in forming the communication between the extremity and the trunk of the animal, yet, under these appa- rently unfavourable circumstances, the delete- rious effects were manifested on the system as in the former case.f Experiments of this description appear to have been sufficiently multiplied to establish the fact, that the poison in these cases passed along the vein, and was conveyed in the general mass of the blood.

The result of these experiments is no doubt very remarkable, and what would scarcely have been anticipated; yet we may remark, that there is one circumstance connected with them, which, in a great measure, invalidates the conclusion that has been supposed to follow so necessarily from them. It may be inferred from the expression made use of, that the poison employed, which was the extract of the upas tree, was inserted by a puncture or incision into the foot of the animal, and would, therefore, in the first instance, be mixed with the blood ; so that the only deduction which we are warranted to draw from the experiment is, that the venous blood, being infected with the poison, had the power of communicating the infection to the system at large.J On this view of the subject we should not regard the above as a case of absorption, but merely as an instance of the power of extraneous sub- stances, under certain circumstances, of uniting with the venous blood and retaining their specific properties.

In connexion with these experiments of M. Magendie and his associates, we have another series which were performed by MM. Tiedemanri and Gmelin, and which bear di- rectly upon the question of venous absorption. Their object was to ascertain whether there

* Magendie, Journ. t. i. p. 25 . . 7. t Journ. t. i. p. 23 et seq. ; Elom. t. ii. p. 183 , . 5. J See llullier, ubi supra, p. 150 . . 2 : and Adelon, " Absorption," Diet, de Med. t. i. p. 148.

ABSORPTION.

27

was any direct communication between the organs of digestion and the bloodvessels except by means of the lacteals. For this purpose they mixed with the food of an animal various substances, which by their colour, odour, or other sensible and physical properties, might be easily detected in the fluids of the body. After some time the animal was examined, and the result was that unequivocal traces of the substances were not unfrequeritly detected in the venous blood and in the urine, while it was only in a very few instances that any in- dication of them could be discovered in the chyle. The colouring matters employed were various vegetable substances, such as gamboge, madder, and rhubarb ; the odorous substances were camphor, musk, assafoetida, &c. ; while, in other cases, various saline bodies, such as muriate of barytes, acetate of lead and of mercury, and some of the prussiates, which might be easily detected by chemical tests, were mixed with the food. The colouring matters, for the most