THE LIBRARY OF THE UNIVERSITY OF CALIFORNIA PRESENTED BY PRO F.CHARLES A. KOFOID AND MRS. PRUDENCE W. KOFOID A MANUAL CONTAINING RULES FOR DISPLAYING THE STRUCTURE OF THE BODY, SO AS TO EXHIBIT THE ELEMENTARY VIEWS OF ANATOMY, AND THEIR APPLICATION TO PATHOLOGY AND SURGERY BY JOHN SHAW, G AN OUTLINE OF THE DEMONSTRATIONS BY HIM TO THE STUDENTS IN THE SCHOOL OF GREAT WINDMILL-STREET. Revised and with Notes by WILLIAM ANDERSON, M D. The first American, from the last London Edition* TROY: PRINTED AND PUBLISHED BY J. DISTURtfELL* 1825, OGY LIBRARY Northern District of Nao-YarK, to wit : BE it remembered, that en the eleventh uay o, June, in the forty-ninth year of the Indepen- dence of the United States of America, A. D. 182o, JohnDisturnell, of the said district, hath deposited r f m ,^ in this office the title of a book, the right whereol he claims as proprietor, in the words following, to wit : ' A Manual for the Student of Anatomy. Containing Rules for Drying the Structured the Body, so as to exhibit the Ele- mentary Views of Anatomy, and their application to Patholog> Tnd SuLry, by John Shaw, being an Outline of the Demonrtra- VionsdeUve^d by him to the Students of the school in Great Windmill-Street. Reused, and with Notes by William Aiiaei- son M D. The first American, from the last London Edition. In conformity to the Act of the Congress of the United States., entitled " An Act for the encouragement of learning, by securing the copies of maps, charts, and books to the authors .d propne- fciso&uch copies, during the times therein mentioned." A ntl Sso to an act, entitled "An act, supplementary to an act, entitled, < an act for the encouragement of teaming, by securing the copi aps, charts, and books to the authors and proprietors of copies during the times therein mentioned,' and extending th benefits thereof to the arts of designing, engraving, and etduug historical and other prints." ^ LANS1NH , Clertcof Gictforth&n Diatrirt C.wrt, ofMti-Y'- 55 Page. INTRODUCTION, containing General Rules for a Student who is commencing a Course of Dissections, xiii. Plan of a Series of Dissections of the Lower Half of the Body, Manner of making the first Dissection of the Muscles of the Abdomen, Description of the Anatomy of the Parts connected with Hernia, and of the method of displaying the several Fascine which have been described by authors, with some observations on the changes which those parts undergo, when Hernia takes place, First View of the Viscera of the Abdomen, Dissection of the Diaphragm and deep Muscles of the Abdomen, .Method of injecting^ and dissecting the^Arteries and Veins of the Viscera, 4> Method of examining the minute Structure of the seve- ral Viscera, 59 Some observations on the manner of examining a Body, to discover the Seat of Disease in the Abdomen, and on the manner of distinguishing the Morbid from the Natural Appearances of the Viscera, 64 Plan which the Student should follow in the first Dis- section which he makes of the Parts in the Perineum, 6& .Manner of making a Section of the Pelvis, so as to give a general view of the Viscera, 80 Description of the Minute Anatomy of the Viscera of the Pelvis, &c. 8:i Dissection of the Perineum, and Section of the Pelvis, to illustrate the operation of Lithotomy, and to show those natural causes of obstruction to the introduction of a Catheter, which are frequently mistaken for Stricture of the Urethra, 85 Some observations on the Changes which the Viscera of the Pelvis undergo, in consequence of disease, 80 Table of the Muscles of the Perineum, 87 - -of the Arteries of the Perineum, 89 IV, CONTENTS. Page. Manner of examining the Structure of the Testicle, ^ 90 of making such Preparations of the Viscera of the Pelvis as may be useful to the Surgeon, Dissection of the Parts in the Pelvis of the Female, of the Uterus and Ovaria, 9S . : of the Muscles of the Thigh, 100 of the Muscles of the Leg, v 1 04 i of the Muscles of the Foot, Arrangement of these Muscles into Classes, Table of the Origins and Insertions of these Muscles, 108 Dissection of the Ligaments of the Pelvis, and of the Joints of the Lower Extremity, Table of the Ligaments of the Pelvis, of the Hip Joint, of the Knee Joint, 1 - ' . of the Ancle and Foot, Dissection of the Arteries of the Lower Extremity, of the deep Veins of the Thigh and Leg, Table of the Arteries of the Pelvis; of the Thigh and of the Leg and Foot, Dissection of the 'Nerves of tho Thigh and Leg, of the Superficial Veins and Lymphatics of the thigh and Leg, Surgical Dissection of the Lower Extremity, 145 Operation on the Dead Body to tie the External Iliac Artery, 146 _ to tie the Internal Iliac, 1 49 . to tie the Gluteal and Ischiatie, & - to tie the Superficial Fe- moral, Observations on the Anatomy of Buboes, : O f Lumbar Abscess, ib. Dissection of the Parts in the Ham, when there is Popli- teal Aneurism, Old Operation for Popliteal Aneurism, as performed of late years by the French Surgeons, To tie the Posterior Tibial and Fibular Arteries, Dissection of the Upper Part of the Body, Plan of a Series of Dissections of this part, Dissection of the Brain, so as to show each part, of the Origin of the Nerves from the Brain, 171 Dissection of the Sinuses of the Dura Mater, Manner of opening the Spinal Canal, > of examining the Brain, to discover the appear < CONTENTS. V. Page* ,iiioes of Disease, and to distinguish the Morbid from the Natural Changes which take place after Death, 174 Some Observations on the difficulty of deciding on the Cause of Death in supposed Injuries of the Brain, 17$ Dissection of the Muscles on the Fore Part of the Neck, 182 Table of the Origins and Insertions of the Superficial Muscles of the Neck, Dissection of the Muscles of the Face, 187 Table of the Origins and Insertions of these Muscles, 18 Dissection of the Doep Muscles of the Neck, 191 Table of the Origins and Insertions of these Muscles, 194 -of the Muscles be- tween the Cartilages of the Larynx, 198 Dissection of the Muscles on the Fore Part of the Chest, 198 Table of the Muscles on the Chest, 190 First Dissection of the Parts within the Thorax,. 201 Manner of Dissecting the Heart, 208 Dissection of the Coats of an Artery, 211 Manner of examining the Parts of the Thorax, to dis- cover the Seat of Disease, and to distinguish the Morbid from the Natural Appearances, 213 Method of injecting the Heart and Great Vessels, 221 Structure of the Mamma, 224 Dissection of the Muscles of the Back, 225 TuMe of the Muscles of the Back, 229 ~ of the Muscles on the Fore Part of the Spine, Ligaments of the Spine, 234 _ . of the Jaw, 237 of the Ribs, 23 between the Clavicles, Sternum, and the first Rib. 240 Method of injecting and dissecting the Arteries and Veins of the Chest, Neck and Head, i}>. 'fable of the Arteries in the Thorax, and of the Neck and Head, 251 dissection of the Nerves of the Neck and Head, with Notes on the Discoveries of Mr. Charles Bell, 258 ~~- : *of the Nerves of the Thorax and Abdomen, with some Observations on the Experiments with Gal- vanism on the Par Vagum, 26,2 , of the Deep Nerves of the head, with some Remarks on Mr. Bell's idea of considering the Vth Nerve as a continuation of the series of Spinal Nerves, 269 Description of the Portio Dura in the Elephant, 274 Deficiency of the Spinal Accessory, or Superior External Jiespfratorv, in the Camel, 27t? .? * CONTENTS, Page* Dissection of the Parts of the Nose and Eaiv 278 of the Eye, 283 of the Muscles and Lachrymal Apparatus of the Eye, 29.2 Method of making certain Preparations of the Eye, Surgical Dissection of the Neck and Head, 296 Dissection of the Arm after it is separated from the Body, 311 of the Muscles of the Upper Arm and Shoulder, ib. Table of the Origins and Insertions of these Muscles, 313 Arrangement of the Muscles on the Fore Arm, 317 Dissection of the Ligaments of the Shoulder and Arm. 322 of the Arteries of the Shoulder and Arm, 325 Table of the Arteries of the Shoulder and Arm, 330 Dissection of the Veins of the Arm, 333 of the Nerves of the Arm, 335 Surgical Dissection of the Arm, 339 Dissection of the Lymphatics, 348 .Description of the Plans, which are intended to illustrate the new arrangement of the Nervous System, by Mr. Charles Bell, nr,e ,iD VERT1SEMENT. THE great improvement made in anato- my within the last fifteen years, has ren- dered necessary something new in the form of a guide to the young practical anatomist'; and minute directions for the dissecting-room have always been receiv- ed with avidity whenever presented. In offering this volume to the student, the American Editor would say, that he has long observed the insufficiency of the . London Dissector to arswer the queries made in the dissecting-room; and had pro- posed to issue a new edition of that work .with such additions as might be necessary ; but finding, that Mr. Shaw's Manual had so far surpassed anything he could attempt in that form, the object was relinquished. This Manual, therefore, is replete witk minute anatomical information, followed up by useful practical deduction ; so that vm. while it may lay claim to the title of a sys- tem of anatomy, it is no less deserving of being considered a particular account oi surgical principle. In possession of Shawls Manual of Ana- tomy, the young student has the most full information concerning the structure and relative situation of important parts, and the best method of procedure for becom- ing acquainted with the same ; while the surgeon has always at hand a monitor thai will prepare him for the exercise of the knife on the living subject. Notes have been added in situations where they were supposed to extend the meaning of the text, and may be distin- guished by a small italic letter, while those 0f the author are referred to by an aster- isk, &c. WHILE engaged in assisting the students, in the dissecting-room, I have been in the practice of drawing up short notes, con- taining rules for the dissection of each part. As J found these to be of much advantage to myself, and of great use to the students, I have been induced, during the leisure oi the summer season, to arrange them in a systematic form. On revising them, however, for the press. I perceive, that I have many apologies to. make for the manner in which they are written: but I have some hopes, that the inelegancies of the language, and the care- lessness of the style, will be forgotten in the assistance which the young student may derive from the hints contained in them. He will find, indeed, that I have been indifferent to every other considera- tion, except that of proving useful to him., m the most difficult period of his anatomi- cal studies, X. PREFACE. One object in the following pages has been, to show the readiest methods by which a student may acquire, in the first instance, a general idea of anatomy ; and secondly, a minute and practical know- ledge, of the manner of exhibiting the struc- ture of each part. Another, and a still more important ob- ject, has been, to direct his attention par- ticularly, to those points of anatomy which are most useful, and the recollection of which, will be of high importance to him. when engaged in the practice of his pro- fession. In this attempt, the student will discover many observations to be those of Mr. Charles Bell : but in excuse for this, he will allow it to be difficult for one, w r ho has either been Mr. Bell's pupil or assis- tant for many years, to write a work on Surgical Anatomy, without showing ja pre- judice in favour of his doctrines and man- ner of teaching. In giving the description ofthemore mi- nute parts, I have taken all possible assis- tance from the best authorities ; for al- though I have spent twelve years in the dissecting-room, during ten of which, I have prepared the subjects for lecture, and have assisted the students, I still find, that no point of ajuatomy can be satisfactorily PREFACE. X*. made out, without referring to the labours of former anatomists. I have made much use of the "System of Dissections," written by Mr. Bell, twen- ty-two years ago, while a student in Edin- burgh, and at a time when the opportuni- ties of studying anatomy were very much restricted. may observe, however, that, notwith- standing the book was written under the disadvantages alluded to, it is from it, that the f. nonymous author of the " London Dis- scvlor" has taken all that is good in his Compilation. Indeed, both the plan and the object of the " System of Dissections,'-" have been imitated by. all who have writ- ten for the use of students in the dissect- ing-room; I am singular, only in acknow- ledging, that I have made free use of it. The observations which are taken from " Pole's Anatomical Instructor," need no apology, since they are my own ; having added them, in the form of notes, to the edition of that book, which was published eight years ago. Of the merits of this work, in facilitating the removal of the obstacles which stu- dents encounter in the commencement of fheir studies, they will be the best judges. To their candid examination I leave it, XII. PREFACE. promising, at the same time, should an op- portunity occur, that, my endeavours shall not be wanting, to clear the obscurities, and supply the deficiencies which they may discover in the present edition; JOHN SHAW .Albany .London, d\i%u*t is*, 1821. INTRODUCTION. AS it is allowed that the sciences of Medicine and Surge- ry, are, and ought to be, founded on Anatomy, there can be no occasion to enforce the necessity of studying 1 Anatomy ; still it may be necessary to offer some advice upon the manner, in which a young surgeon should prosecute the acquirement of the knowledge of this important branch of science. When I entered upon the study of my profession, I was taught, never to lose sight of the chief end of anatomy; and my attention was directed particularly to those parts, the re- collection of which, would be of use, when left to my own re~ sources. This advice I would wish to impress particularly upon those students, who, from circumstances, are not able to remain longer than one ot two seasons in London. I shall even ven- ture to advise the student, whose time is limited, not to ha- rass himself in acquiring such a knowledge of anatomy, as consists in a particular description of the seven-and-twenty processes of the sphenoid bone, or the exact origins and in- sertions of the multifidiis spinse ; nor to burthen his memory with certain Latinized names, at best but barbarous com- binations, which are given by some dissectors, to branches of arteries, in themselves so small, that, if cut, they would not throw out more than one jet of blood ; and so irregular, that they are seldom seen twice in the same relative position. When such a knowledge of anatomy as this, is considered to be of importance, it is not surprising, that the opportunity of studying what is truly useful, should be lost, and that the student should contemn the science altogether, when he be- comes a surgeon. He then finds, or is too apt to consider, that the only advantage which he derived from the study of a- natomy, was, that it enabled him to pass certain examinations I trust, that the contents of the following pages will prove, that notwithstanding what I have here said, I do not intend to disparage the knowledge of minute anatomy: on tho contrary, I contend, that no man can be a thorough good surgeon, without that knowledge ; but it must be a very dif ibrent "minute anatomy," from that of being able to give the accurate description of the shape and facits of a dry bone: or of the points, from which some deep muscle of the I arises, although expressed even in that technical language-, which appears so imposing to a beginner. B XiV INTRODUCTION. To counteract the effect of the long and hard-soundm* terms, these " sesquipedalia verba," which unfortunately have the effect of leading a young student to suppose, that the more difficult the name is to recollect, the greater neces- sity there is, of studying the part which it denominates, I would advise him, while he is engaged in the dissecting- room, to read those hooks on medicine and surgery, which are founded on the facts of anatomy. By such a course of study, he will be directed to the proper subjects of inquiry ; and he will also have the best chance of becoming so acquaint- ed with the changes produced by disease, that he willnotbe in danger of being discomposed and alarmed at their appear- ance, nor be obliged to stop in the middle of a perilous ope- ration, should he find the parts not exactly in the situation as demonstrated in the dissecting-room, or exhibited on the ta- ble of the lecturer. It would scarcely be believed, that I have occasionally found some difficulty in impressing the importance of such a course of study ; a difficulty originating in an advice which is given by many, to students, viz. " not to read" and this upon the authority of Mr. Hunter. I shall only ask, What kind of anatomy would nine-tenths of the students, who arc to spend only a short time in London, learn ? or of what use would it be to them, if their views were not properly direct- ed, by the study of good books ? The argument in favour of not reading, is, that the first impressions of a student should be derived from the dissected body. With this opinion, I most cordially agree ; but this argument offers no reason, why students should not, at the same time, take advantage of the hints contained in books, written by those who have known how to attach the due degree of importance to each part. Perhaps it will be allowed, that the probable conse- quence of the advice of not reading, is, that the student never reads a bookxm the subject, but is apt to become one of those self-taught geniuses, who, throughout his life, is making ab- surd and fancied discoveries in anatomy and surgery. I have often found, that the sarac students who have been advised not to read, have also been told, that they should not attend the dissecting-room during the first season of their studies; but, that they should acquire their first ideas of anatomy, from the appearance of the dissected body on the lecturer's table. Surely there is an inconsistency in these two opinions; the latter can never have been given by those who have had extensive opportunities of seeing the course of a student's progress. I would advise a student to attend the operations in the dissecting-room, from the first ; for though he should not uss the knife himself until he has a general idea of thegtruc- INTRODUCTION. XV lure of the body, he will have an opportunity of correcting the erroneous notions which he necessarily forms, from the exhibition of the parts, as prepared for demonstration on the lecturer's table; for he will discover how much must neces- sarily be taken away, to make the muscles, arteries, or nerves sufficiently distinct for public demonstration. But the more serious objection is, that a student who delays commencing- dissection until he has attended several courses of lectures on anatomy, never makes much proficiency in it, nor ever goes con amore to his task ; perhaps there may be a moral cause for this. The student finds, that those who commenced the study of anatomy, at the same time with himself, and who have been, from the first, attending the operations in the dissecting-room, are much farther advanc- ed in the actual knowledge of the parts ; he is ashamed to begin, knowing that his old companions are already adroit, and conscious that he must make an awkward exhibition ; indeed, I have frequently found that .students so situated, have, in the course of an hour, (to show somo dexterity,) 'finished -the" dissection of a limb; but, of course, in a very imperfect manner. It is surely needless to impress upon the student, that though he may be able to point out any part of the body which is exposed, he can never be a dexterous, nor even a safe operator, unless, he practices dissection: indeed, the question of the propriety of a.- man attempting to operate* who has never dissected, resolves itself simply into this ; as an operation is only a nice and difficult dissection, is the first essay to bo made on the living body? I would recommend the student not only to dissect the im- portant vessels, &c. with unwearied diligence; but also to practise himself in removing the cellular membrane from the larger muscles,* as it is the most likely way of giving him that peculiar command of the knife, which is so important for a surgeon to. possess, and which cannot be attained ex- cept by much practice. In proof of this, we see that when even a man who is naturally dexterous, takes the knife into his hand for the first time, he appears awkward; and the spectators at once per- ceive, that he is not familiar with the use of the instrument. * More use should be made of the bodies of animals than is., generally done. In a surgical view, the dissection of them can only be of use in giving a degree of familiarity in the manage- ment of the knife : but they are of great service in every ques- tion regarding the minute structure of a part, or of its function, nnd particularly in the investigation of the nervous system, or of tructure of the organs of sense, or of the viscera, Much of the appearance of dexterity, and even real dex- terity, being dependant on the manner in which an instru- ment is held, we ought to study what is the best and neatest mode ; taking care, however, to avoid the appearance of af- fectation. To perform almost any dissection, or operation, the knife should be held nearly in the same manner as we do a pen ; the motions should be executed with the fingers and wrist only, for in this way, the incisions will be made with more freedom and precision, than they can, when the shoulder, elbow, and hand are moved at each cut ; which they must, if the knife be held between the thumb and all the four fingers. It has been said, that Mr. Hunter used to hold his knife in this manner ; but on asking an old and fa- vourite pupil of Mr. Hunter, and who is yet famous for his dexterity in operating, and neatness in dissecting, whether This was true, he told me, that it was so ; but that the joint of Mr. Hunter's thumb was stiff, inconsequence of an accident. The student will find that he requires several instruments, besides those generally put into the dissecting case, to ena- ble him to make some of the more difficult dissections. Thus, for example, he could not dissect the nerves of the spine, nor of the head, without a small saw, two or three cliisels of different sizes, a small mallet, and the strong pin- cers, (that are used to pull out nails;) the knife (called a hacking knife,)which is used by plumbers to cut lead, will also be found very convenient.* For the more minute dis- sections, he will require two small hooks, and a sharp steel point ; the etching tools which are used by engravers, are very useful; particularly if the points are bent a little, as wo can then easily tear away the cellular membrane from the small nerves, f It is perhaps* unnecessary to say that the student should endeavour to prevent the bad effects of sitting several hours in a cold dissecting-room : the most effectual way, is, to put on an additional flannel jacket, and carpet shoes over his boots. I would, moreover, advise him, for the comfort of himself and his friends, to make a distinct rule, never to sit in the dissecting-room, with the coat which he wears through the day; but to keep one for the purpose of using while he is there. A cap should be worn, in preference to a hat, which is not only inconvenient, but also very quickly ac- quires a bad smell. * All these things may be got at a carpenter's tool shop ; th^ chisels which are used for cuttrng iron, are the best. t It is necessary to have one or two coarse cloths, to cover thn parts which have been dissected; as they very quickly spoil when left exposed to the air. FIRST DISSECTION MUSCLES OF THE ABDOMEN. IT is not of much consequence what part of the body the student dissects first. I shall here suppose, that he is to Commence with the lower half of the body, which includes idl the parts below the chest. But as this would be too much for one pupil to accomplish, it should be taken by two, between whom there ought to be a good understanding, as they will necessarily interfere with each other in their ope- rations, and particularly in the dissection of the viscera of the abdomen and of the pelvis. Before describing the manner of making each dissection, 1 shall endeavour, in a general way, to point out the best plan of proceeding. As a student ought to acquire only elementary views of Anatomy at first, he should commence'with the dissection of the origins and insertions of the abdominal muscles. After having dissected the muscles, he should examine the viscera. Having removed the viscera, he may dissect the deep muscles of the abdomen. If the body be a male, he should then dissect the muscles of the perineum ; and having made himself acquainted with them, he ought to make a perpendicular section of the pel vis. that he may examine the parts contained in it. The first dissection of the thigh and leg should be of the muscles and ligaments only. The plan which the more advanced student should follow is very 'different from this which I have laid down for the be- ginner ; I shall not enter upon it at present, but proceed to describe the manner in which the first course of dissection is to be prosecuted. DISSECTION OF THE MUSCLES OF THE ABDOMEN. The first observation which I shall make upon this d tion, is, that the student must not be disheartened if in his attempt he does not make -such a display of muscular ' 18 Bbres and glistening tendons, as he may sometimes see ex- hibited on the table of the lecturer; because it is really very difficult to make a neat and complete dissection of these muscles. I have already remarked, that the student must, in his first dissection, be content with making himself master of the general connections of the muscles only; for until he has done this, he is not prepared to study the surgical anatomy with advantage. Before commencing the dissection, the fibres of the muscles should be put upon the stretch by placing the body in a pro- per position,,. This may be done by putting a large wooden block under the loins, by letting the legs hang over the table,, and by throwing the arms towards the head. When the body is put in this position, an incision is to be made through the integuments, in the line of the linea alba* extending from an inch above the ensiform cartilage to the, symphysis of the pubes. A second cut should commence at the upper part of the first, and be carried in a semicircular direction over the chest to the posterior superior spinous pro- cess of the ilium. An incision from the umbilicus to the os- seous part of the sixth rib will facilitate the dissection. The student should now commence the dissection of the first, muscle, (external oblique,) at the cross cut ; and as this is, supposed to be his first attempt, I shall give a particular de- scription of the manner of proceeding. The cutting edge of the knife is to be placed perpendicular to the muscular fibres on the margin of the ribs, and is to be carried in the line of the incision towards the umbilicus. The knife may be set boldly on She fibres of the muscle which are between the ribs and the linea semilunaris ; but between this line and the um- bilicus much caution must be used, as the muscle forms a tendinous expansion here, which is frequently mistaken by the young dissector for cellular membrane, and thus the ten- don of the muscle is improperly lifted and cut away. In dis- secting this tendinous part, the edge of the knife should not be held perpendicular to the tendon, but rather in a slanting direction. After some fibres of the muscle have been ex- posed in their whole extent from the origin on the ribs to* their insertion into the linea alba, the forceps may be laid aside, and then with the finger and thumb of the left hand^ the flap of skin should be pulled downwards and outwards, so as to make the fibres of the muscle still more tense. The dissection is to be continued, in the manner already described^ down to the ilium. As the cellular membrane becomea- denser, as we approach the groin, it maybe mistaken for the tendon, but if it is not at once removed with the skin, it wLft 19 be difficult afterwards to make the muscle clean by dissec- tion with the forceps. The upper part of the muscle is now to be exposed. It is difficult to do this part of the dissection neatly ; we should, again commence at the cross cut, and carry the knife in direction parallel with that incision. The part of the muscle nearest to the ensiform cartilage must be dissected with great <'are, because it is very thin, and is liable to be raised, so as to expose the origin of the rectus, which confuses the young dissector exceedingly. The whole of the external oblique will now be seen ; but to make its serrated origins appear more distinct, a small part of the pectoralis major and latis simus dorsi should be dissected. The method which I have now proposed, is the easiest for the young dissector ; but the student who is accustomed to dissection need not make the- cross incision from the umbilicus to the. semicircular cut, but may commence at the sternum, and carry the flap down to- wards the ilium. I shall give the description of the origin and insertion of the abdominal muscles fuller than those of any of the other muscles, because I frequently see the young student experi- ence considerable difficulty in showing them. The obliquus dcscendens, or externus, may be seen to arise, by seven or eight distinct portions, from the seven or eight inferior ribs. Thc- four or ve upper portions mix their digitations with corres- ponding slips of the serratus magnus, and the two or three lower with the latissimus dorsi; sometimes a slip unites with the pectoralis major. The muscular fibres proceed obliquely downwards and forwards, and, at the semilunar white line r terminate abruptly in a thin tendon, which is united with the muscle of the other side, at the linea alba. The tendon is so thin at the upper part, that the muscular fibres of the rectum may be seen through it ; this is the part already described as very liable to be raised by the young dissector. While the tendinous expansions of the muscles of each side are united in the middte of the abdomen, so as to form the superficial part of the linea alba, the more oblique fibres are inserted into the two anterior thirds of the outer crista, and to the anterior superior spinous process of the os ilii, to the os pubis, and to the whole length of Poupart's ligament. The spermatic cord in the male, and the round ligament of the uterus in the fe- male, may now be seen passing between the tendinous fibres- of the muscle. This opening is called the external abdominal ring. The dissector should not now be particular in his at- tention to it, but wait until he makes the surgical vieir, v> h will be afterwards described. 20 We may now look to the general appearance of the muscle- First, the origins of the muscle from the side of the thorax, come down in thin layers over the rihs ; then a stronger and more fleshy part is seen winding round betwixt the false ribb- and the ilium ; the expanded tendon on the fore part of the belly, is bounded by the linea alba; and the muscular fibres are divided from the tendinous part by the linea semilunaris, which is that tendinous white line which runs, in a curved direction, from the os pubis to the margin of the ribs. In the space betwixt the two lines thorectusis indistinctly see a through the semi-transparent tendon, and intersected by white bands, whicli are formed by the union of its intermediate ten- lions with the tendons of the oblique muscles. In the middle of the linea alba the remains of the umbilical opening will be seen. It appears like a perforation in the tendons, and is filled up by a dense cellular substance, the re- mains of the umbilical vessels. The peritoneum will ..after- v/ards be found firmly attached to this part.(a) To dissect the next muscie, (internal oblique,) the body j-hould be thrown a little more upon one side. The dissection is to be begun by separating the serrated origins of the obli- quus externus from the ribs, and from its connection with the latissimus dorsi. The external oblique is then to be held as if it were the skin, and is to be detached from the internal, by carrying the knife in a direction parallel to the fibres of the latter, taking care to leave the cellular membrane which lies betwixt the two, on the external muscle. It is difficult to separate the two muscles from each other at the upper part', farther than the linea semilunaris, for at this line their ten- dons are united firmly ; but on the lower part of the abdomen, the whole extent of the internal oblique may be easily shown by cutting through the attachment of the external oblique to the ilium and Poupart's ligament. It is not easy to deter- mine which should be the origins, and which the insertions of the internal oblique, for the origin may occasionally be con- sidered as the insertion, and vice versa. Here, we may de* scribe it as arising from the two-thirds of the iliac portion of Poupart's ligament ; from the whole extent of the spine of the ilium; and from that fascia formed by the tendons of cer- tain muscles of the back, which is called fascia lumborum (this origin is sometimes described as from the lowest lumbar vertebra and os sacrum, by a tendon, which also gives origin (a) From this circumstance, umbilical herniae by some authors have been considered as always wanting a peritoneal sac. The covering oi these ruptures appears simple; from the membraiu being impacted with the common integuments. 21 t,o the serratus posticus inferior.'} The fibres which rise froift the posterior part of the spine or the ilium run obliquely up Wards, to be inserted by fleshy fibres into the three lowest ribs, and by a thin tendinous membrane to the four next ribs. The fibres which arise from the middle of the spine run to- wards the linea alba ; but at the linea semilunaris the tendon splits, and one portion having united to the tendon of the ex- ternal oblique, runs anterior to the rectus, and is inserted to the whole extent of the linea alba while the other portion of the tendon, which passes behind the rectus, is not attached to the whole of the linea alba, but is gradually lost about half way between the umbilicus and os pubis ; so that the whole of the rectus is not contained in a sheath. That portion of the internal oblique which arises from Poupart's ligament is inserted into the tuberous angle of the os pubis : but here there is a set of fibres which sometimes confuse the dissector ; they are seen distinctly in the male only, for they form the cremaster muscle; they arise generally from the internal oblique, but sometimes from the ligament; they cover the spermatic cord, pass with it through the ring, and are lost upon the upper part of the tunica vaginalis testis. Unless we are at liberty to put the body into whatever pa* feition we please, it will be very difficult to dissect the next muscle ; and it will be almost impossible to show all its origins before the muscles of the back are dissected ; for its fibres rise from the edges of the eleventh and twelfth ribs, and from the transverse processes of the last dorsal and the four supe- rior lumbar vertebra; so that, coming from this deep source, they must pass between the quadratus lumborum and sacro lumbalis. Therefore, at present, w r e can show only the con- nections which the transversalis has with the muscles on the anterior part of the abdomen* We may commence by rais- ing the attachments of the internal oblique from the cartila- ges of the ribs, from the fascia lumborum, and from the spine of the ilium ; but it is very difficult to separate the lower edges of the two muscles from each other, for they lie so close together, that, in raising the attachments of the oblique, we are apt to lift the transversalis also. The separation is most easily begun at the spine of the ilium, for there is a .small artery here, which marks the line of "division between the muscles. In this dissection we must not expect to make the transversalis appear very clean; for we must carry the knife across the line of the fibres. It will be difficult to carry the obliquus farther than the linea semilunaris, for there, the tendons of the two muscles are intimately united. The tendon of the transversalis being :**f Mched to the posterior portion of the. obliquus, passes with 22 it behind the rectus, from the ensiform cartilage to a point midway between the umbilicus and pubes, and there it passes anterior to the rectus, with the obliquus, and is inserted with it into the os pubis ; so that at the lower part of the abdo- men both muscles pass anterior to the rectus. It will be af- terwards found that there is only a little cellular membrane between this part of the rectus and the peritoneum. When the internal oblique has been raised so as to expose the whole of the transversalis, we shall find that its origin and insertion are very similar to those of the obliquus interims ; but it is generally described as arising from the cartilages of the seven lower ribs, from the fascia lumborum, from the transverse processes of the last dorsal and the four superior lumbar ver- tebrae, from the spine of the ilium, and one third of Poupart's ligament ; the fibres then pass to the linea alba and pubes. "The muscles which remain to be dissected are the rectu? and pyramidalis. The most important part of the anatomy of the rectus is its sheath. It has already been seen that it is formed by the splitting of the tendon of the internal oblique, to the anterior portion of which, the tendon of the external oblique is attached, while the tendon of the transversalis unites with the posterior layer. The rectus itself may be exposed by cutting through the tendon of the external oblique and the anterior layer of the internal oblique, at their attachment to the linea alba, but some difficulty will be ex- perienced in separating the sheath from the belly of the muscle, in consequence of the linear transverse. The muscle will be found at its lower end to be attached to the symphysis pubis, and at the upper to the ensiform cartilage and the car- tilages of the fifth, sixth and seventh ribs. At the lower part of the belly, a pyramidal set of fibres will generally be found, forming a distinct muscle, called the pyramidalis. It arises from the symphysis pubis, and is inserted into the linea alba, about two inches above the pubes. The parts being thus dissected, can be demonstrated in fjuch various views, and with such quick succession, that they cannot fail to be effectually understood. And having care- fully observed their strict anatomy, no one can be at a IOSF to recapitulate their general character and uses. It maybe observed in the skeleton how great a space there is to be covered from the edge of the thorax to the brim of the pelvis, and backwards to the spine; and recollecting, that in this space are contained the soft viscera of the abdomen, and that these must be sustained by an elastic and yielding covering, it will be understood how this covering, whilst it supports the viscera, and yields to and assists the operations vif the diaphragm, must support and poise the whole trun& 23 upon the pelvis ; and that although the muscles are thin ari delicate, yet, having so great a lever as. the edge of the tho- rax, while the centre of motion is in the spine, they must bend the upper part of the body with great force. We may now perceive that the abdominal muscles are muscles of respira- tion, that they are muscles of the trunk, and that they com- press and retain the viscera. Considering them as muscles of respiration, the student will be led to understand how pe- culiarities in the manner of breathing become a symptom of disease, and why we endeavour to substitute the action of these muscles, and the diaphragm, for the external muscles of respiration, in fractures of the ribs, sternum, &c. The question, Do the viscera of the abdomen suffer an un- ceasing pressure ? is a very important one. When on this subject, we are led to consider how the effects of pressure of the abdominal muscles may become a means of diagnosis in diseases of the abdomen ; and what are the effects of the re- moval of pressure by the delivery of the child, or the drawing off the water in ascites. Jut still, the most important subject of inquiry in the dis- gection of the abdominal muscles, is," the anatomy of the openings by which the intestines generally protrude in ingui- nal or femoral hernia. But before the young student can at* tend with advantage to this subject, he ought to make him* self master of the dissection of the viscera of the abdomen, and of the muscles and arteries of the thigh However, be- fore describing those parts, I shall here introduce part of a, paper which I published some years ago, descriptive of tha anatomy of hernia. ANATOMY OF HERNIA. It must have been remarked by every one who has been much in the society of students, that there is no subject^ which they are so anxious to comprehend as the anatomy of henna. Those who have read much on the question before they haVe dissected the partb, begin in utter hopelessness of understanding the subject; but if they be directed in their operations, they will, in the second or third attempt, make an accurate display of the parts ; but still they will not be satis- fied ; they believe that there must be something mysterious and unusually difficult in those fascice which have received such various names, and have required such extraordinary descriptions. They cannot imagine how turgeons can have puzzled themselves, and bewildered their readers, with that which they now think they find perfectly simple. We need not be surprised at this difficulty, since the descriptions which 24 &re given by some authors are quite at variance with true anatomy ; while those views which are really correct, are given in so complicated and obscure a manner, that it is almost impossible, even for a man who is conversant with the anatomy of the parts, to follow them. In the best authors there are omissions, which have been in a great measure the cause of the student's difficulty. A principal one is, the forgetting to describe the state of the body from which the views have been drawn. In a thin anasarcous body, all the fasciae that have ever been described inay be easily shown : the fascia transversalis will be so dis- tinct, that a student, even in his first dissection, can make out the internal ring, according to the description given by Mr. Cooper; while in a fat subject, this will be a difficult task for even the experienced dissector. Unless the student be told how to place the limb, and how to use the knife in the dissection of the parts concerned in femoral hernia, it will not be possible for him to show the various crescentic fasciae. The young dissector naturally proceeds with a sharp knife, to clear away the fat, glands, and cellular membrane, while the limb is lying in a straight line ; by doing this, he cannot avoid cutting through all the connections of the fasciae, so as to destroy all resemblance to those views which have been taken by merely detaching the loose cellular membrane and glands with the handle of the knife, while the legs were forcibly separated from each other. We shall endeavour to simplify this piece of anatomy by giving an account of the manner in which the dissection is made in the Dissecting Rooms of Great Windmill Street, and we shall add, in the form of notes, the names which have been given to the several fasciae by the various authors who have written on the subject. It is of considerable importance in this dissection to have, a good body. That of a strong muscular man is not so well adapted for the display of the anatomy of the groin, as that of a person who has died of a lingering disease. The body of a male is the best for the dissection of the inguinal canal, and that of a female for the parts connected with femoral hernia. The subject is to be so placed that the abdominal muscles may be made tense : this is most conveniently done by plac- ing a block of wood under the loins. To put the fasciae of the thigh upon the stretch, one leg ought to hang over the side of the table. The dissection of the upper part of the exter- nal oblique is to be made according to the general rule of re- moving all the cellular membrane from the muscular fibre; but this plan must not be followed lower down than to a line drawn from the one anterior superior spinous process o-' 25 tliuni to the other ; here, the skin only should be raised ; i? may be carried down to three ringers' breadth below the line of Poupart's ligament.* By this method we shall .leave upon the groin a quantity of condensed cellular membrane, between the layers of which is the arteria epigastrica superficialis ; this membrane may be traced from that which covers the pectora- lis muscle and the upper part of the muscles of the abdomen ; it has generally received the name of fascia superficialis coin- munis, because it is of equal importance to the inguinal and femoral hernia. This facia f is now to be dissected from the tendon of the external oblique. It has a very slight attach- ment to the expanded tendon, and the union between it and the spermatic cord is' so slight, that the handle of the knife can be pushed between them as far down as to the bottom of the scrotum. The attachment between the iliac! portion of Poupart's ligament and this facia is very strong ; but the connection between the pubic portion of the ligament and the fascia is so slight, that the handle of the knife is suffi- cient to destroy it. We can separate the fascia with great, ease for about an inch below the edge of this part of the lig- ament, but we cannot lift it farther without using the knife ; for the fascia becomes intimately united to the inguinal glands and to the fascia lata. Although we have raised this fascia, the accurately defined pillars of the abdominal ring, which are generally represented in plates as the first stage of the dissection, will not yet be visible ; but farther dissec- tion will be required, to show them ; for a fascia, which shall be presently described, covers the ring, so that only a pro- minence is seen, and which we shall find to be formed by the spermatic cord. It is of great importance to make this dissection in the manner that has been pointed out, because much of the pa- thology of femoral hernia may be explained by it. By look- ing narrowly into the depression which has been formed by raising the fascia superficialis, we may see lymphatic vessels passing across from the glands to perforate a membrane, * Tendon of the external oblique , Fallopian or Poupart's liga- ment; crural arch ; ligament of the thigh ; femoral ligament. t Fascia superficialis of Mr. Cooper ; described by Camper and many others as only a membranous layer ; by Scarpa, as a pro- longation of the fascia lata. In the scrotum of the foetus it forms the external lamina of the peritoneum of Langenbeck, J The terms-iliac and pubic are better than external end inter- nail. The length of the Poupart ligament may be divided into three portions : two of the thirds are called iliac, the other pitbic 9 b/*ibg that which is nearest to the pubes, C 26 which, though it appears to be a continuation of the lower &dge of Poupart's ligament, has been, by some, described as a uistinct fascia, under the name of cribi^iform, in consequence of the appearance which it presents when the lymphatics are cut short. Occasionally a small gland is projected through the membrane. The general course of the femoral hernia is either to displace this gland, or to break through the meshes of the net-work ; and then it will pass into the hollow which we have just described. The natural course of the hernia would be, to descend upon the thigh ; but it is prevented from passing farther down, than about an inch, on account of the close connection which exists between the fascia su- perficialis and the glands of the groin ; but when the hernia increases in size, as it is prevented from descending upon the thigh, it turns up and breaks through the slight connection which there is between the pubic pail of the ligament and the fascia superficialis, and thus takes the place of an ingui- nal hernia. This explains to us that the acute angle made in the gut is the principal cause of stricture in femoral her- nia ; and from the knowledge of this, we deduce principles upon which we must proceed to attempt the reduction of femoral hernia, when so situated. We must endeavour to bring the base of the sac to a straight line with the neck ; and to succeed in doing this-, we must first push the tumour downwards. It has occasionally happened that a femoral hernia has passed up before the surgeon had finished the operation. We have heard the surgeon blamed for operating in such a Case. It has been said, that the gut going up before the stricture was cut, proved that there was no necessity for the operation; but instead of joining in the censure, we think that it would be even advisable, in some cases, to cut through the fascia superficialis, so as to allow the sac to come to a straight line, rather than to persevere long in the use of the taxis. All who have seen many cases of femoral hernia must allow, that a cut through the skin and fascia, in an early stage, in many cases, would not be so dangerous as a pro- tracted attempt to reduce the gut by the taxis. We have further to consider, that if it be not possible to reduce a her- nia, after having cut through the fascia superficialis, that it never would have been reduced by the taxis ; in that case all the steps of the operation must be performed. We now return to the anatomy of the inguinal hernia. I we pull the spermatic cord towards the scrotum, we shall see a thin fascia passing off from the tendon of the external oblique and attached to the cord. It has been called fascia propria. It is very strong in cases of old hernia; but even in thenatu- 27 ral state of the parts, it is so distinct that it obscures thejnar* gins of the ring, (a) By cutting this thin fascia where it is con- nected with the cord, and by letting go the cord, the upper part of the pillars of the ring will be distinctly shown ; but to make the opening of the ring quite apparent, we must remove the loose fat with the forceps and scissars from the lower part of the cord; we shall then have such a view as is given in plates as the first stage of the dissection.* This opening has been called a ring, but it might with more reason be described us a triangle, the base of which is the os pubis, and the apex the splitting of the tendinous fibres of the external oblique, and which is rounded off by a set of cross fibres. The' supe- rior side, or pillar , is simply inserted into the symphysis pu- bis ; but in the attachment and form of the lower pillar there is a provision to prevent the compression of the spermatic cord during the contraction of the muscles, and it is thus the inferior pillar is formed by the pubic extremity of Poupart's ligament, which is not a rounded tendon that, viewing it on ?,he outside, we should expect it to be, but it is so formed that part of it passes onwards to be attached to the linea ileo- pectinea by a flat broad horizontal tendon, while its more ex- ternal part is inserted into the tubercle of the pubes; so that: by this form of insertion there is a groove made for the lodg- ment of the spermatic cord. The tendon of the external oblique is now to be cut through in two directions ; one in a line drawn from the superior ante- rior spinous process of the ilium to the linea alba, and the other in the linea alba to the pubes. The tendon of the ex* ternal oblique is to be carefully separated from the internal oblique, and is to be fastened by a hook to the fore-part of the thigh. This will give us a view of a great part of the inguinal (a] While the fascia superficialis was overlooked ; Camper described a covering to the cremaster muscle, extended from the edges of the external abdominal ring. This, however, has -since been traced in continuation with the fascia superfi- cialis; is a part of that fascia ; and covers the cremaster as the extended aponeurosis does the other superficial muscles of the body. I would rather retain the name of Camper's fascia, to this slip of the superficial fascia ; than call it fascia propria ; lest it might be confounded with the fascia propria. of a femoral hernia, that is derived from the cribriform por- tion of the crural sheath. * Inguinal ring; ring of the external oblique; or external abdominal ring. The anatomy of the canal is most accurate- ly described in the folio edition of Mr. Charles Bell's Jfecc- published in 179U. 28 '; onaL The cord will be seen lying under the lower margii; of the internal oblique, and so connected by cellular meln- brane to the edge of the muscle, that it is difficult for a stu- dent in his first dissection to tell what is muscle and what is cord. This is in a great measure owing to the cremaster muscle, for it certainly varies considerably in tho manner in which it takes its origin ; the view may be made more dis- tinct by pulling the cord in a direction towards the scrotum, and talking off the cellular membrane from it and from the margin of the internal oblique. By doing so, we shall see that the internal oblique is not attached to the whole extent of Poupart's ligament, but that, at two inches and a half from the symphysis pubis, its attachment to the ligament ceases ; It then passes, in the form of an arch, to the tubercle,* and to the linea ileo-pectineaf of the os pubis, so as to assist in clo- sing the space behind the external ring. At the termination of the connection of the internal oblique to Poupart's liga- ment, the fibres w^hich form the cremaster muscle come off; but as these fibres occasionally arise from Poupart's ligament, the cord sometimes appears to perforate the internal oblique ;t but in the greater number of cases, it is sufficiently clear that the cord passes under the internal oblique, not through it- In this part of the dissection we may observe a nerve running through the internal ohlique to pass on the cord, it is the spermaticus superficialis. The next stage of the dissection is to show the relation of the transversalis to the cord. It will be very difficult to raise the internal oblique from the transversalis, if we commence the separation at the lowe^ edge of the muscle; but by cutting through those fibres of * Spine of the os pubis; tuberculum spinosum; tuberosity of the pubes. f Linea ileo-pectinea ; linea innominata, continuous with the crista. | M. Cloquet describes the cremaster as formed by some fibres of the obliquus internus, which are pulled down by the testicle and gubernaculum, during the descent. He says that these fibres have two distinct attachments, one to the belly of the obliquus internus, and the other to the os pubis : so that each fibre forms a loop (des arises,) similar to extensible cords, which, when fixed at their two extremities, are drawn down in the middle. He also says that the testicle occasionally passes through the substance of the internal oblique, and then, the same appearance of fibres is found both before and behind the testicle ; and that an inguinal hernia in a female frequently pushes down some of the fibres of the interna i oblique before it, so as to form " un mmcle cremastw accident?!. ' 29 the internal oblique, which are connected with the superior anterior spinous process of the ilium, we shall find some cel- lular membrane, and a branch of the artery called circumflexa iJii, lying 1 upon the transversalis muscle, which will mark the line in which we are to dissect,, so as to raise the- internal .oblique from the transversalis. The internal oblique is to be separated from the transversalis, and from its connection with Poupart's ligament, as far as the origin of the cremaster, and it is then to be turned over 'towards the linea alba. The whole of the margin of the transversalis will now be seen, and we may observe that its relation to the cord is very nearly the- name as that of the internal oblique ; indeed, the tendons of the two muscles are so closely connected with each other, that it is almost impossible to separate them. It will be also ap- parent that the united tendons of these muscles, by their in- sertion into the linea ileo-pectinea, form the grand protection against hernia taking place through the external abdominal .ring ; but when this part is weak, In consequence of the defi- ciency of the tendons, that hernia which is called direct, or xcntro inguinal^ may take place. The muscular fibres of the transversalis are now to be very carefully detached from Pou- part's ligament, and then they are to be scraped, not cut. from the layer of condensed cellular membrane, which k called the fascia transversalis.* We have seen the cord pass through the external obliquo. and under the margins of the internal oblique and transver- salis, and we should now see the internal ring, described by Mr. Cooper ; but this ring must be made. When we pull th< cord towards the groin, we see part of the cellular membrane which lies under the transversalis muscle passing down upon it in a conical form: If we cut this membrane from the cord, and push it up, and then let the cord go, there will be a hole, formed in the shape of a ring, but which, on its iliac side only, has a distinct margin, for on its pubic side there is only tlit *. .cellular membrane surrounding the epigastric artery and veins. We may observe also, that the cord at this point has lost its rounded form that the vessels are not bound toge- ther, as they are at the external ring, but that the component , separating from each other, give the cord a flattened form. Having now made an internal ring,(-t) we should at- * Fascia transversalis, of Mr. Cooper; fascia longitudina- lis, or reflexa, of M. Cloquet ; condensed cellular membrane between the peritoneum and transversalis muscle, of many authors. (a)' This opening is not the creature of the knife, but exis! '< boitrc dissection has commenced, as perfectly as that on 30 tend to the situation of the epigastric artery. It generally arises from the pubic side of the external iliac artery, just be- fore it passes under Poupart's ligament. It will be found to descend a little, and then to proceed upwards towards the rectus, passing upon the pubic edge of the spermatic cord, and between the fascia transversalis and the peritoneum ; it tnen enters the substance of the rectus, about midway be- tween the pubes and umbilicus. As this artery is always on the pubic side of the spermatic cord, it follows, that when the inguinal hernia passes along the spermatic passage, (which it does in nine out often cases,) the epigastric artery will be on the pubic side of the hernia ; but in the direct or ventro inguinal hernia, the artery will be on the iliac side. Let us now trace the course of a common hernia to the scrotum, and show what coverings it may have, and what are the probable causes of stricture. The muscles and the peritoneum may be cut through in the usual way of exposing the viscera, and the flap held out so that the inside of the peritoneum, and the depression which is found at the part where the cord passes into the canal, may be seen. In the greater proportion of cases, it is at this point that hernia takes place. Having laid down the transversalis and internal oblique again in their natural situations, if we push the finger from "within downwards into the depression of the peritoneum, we shall exhibit in appearance the first stage of the descent of a hernia. The finger is as the sac would be, above the cord, and on the iliac side of the epigas- tric artery : by pressing forward the finger, and through the peritoneum, it will appear under the margins of the trans- versalis and internal oblique ; and if pushed farther, it will pass through the external ring. A hernia lying at this point, would be called inguinal hernia; but if it were to descend as far as into the scrotum, it would be called scrotal hernia. This is the common course of an inguinal hernia, but its rela- tion to the cord occasionally varies. When we look to the flattened and dispersed state of the cord at its upper part, we can understand how it may be split by the descent of a hernia- ry tumour. In such a case, the vas deferens is sometimes found on the anterior part, and the vessels behind ; but the vessels are more frequently on the fore part of the sac. We may now show what coverings the sac of a hernia would receive in its passage to the scrotum. In the common inguinal hernia, the peritoneum pushes be- fore it, that cellular membrane which has been called part of upper part of the cone of a funnel, by which, the pipe is con- jcl with the body of the article. 31 lie trans versalis fascia, and which we showed must be sepa- rated from the cord before the internal ring can be made ; this, when condensed, forms the innermost covering of the sac. The hernia then passes under the trans versalis and in- ternal oblique, and as the cremaster muscle runs from the in- ternal oblique to the cord, it follows, that if the hernia lies above the cord, the sac must be between the cremaster and the cord ; the fibres of the cremaster which lie above the sac will then be separated, by it, from each other, so that the cel- lular membrane which connects the scattered fibres, will form that which is called the cremastic or spermatic fascia. The hernia then passes through the external ring. In the early part of the dissection, there was a membrane shown passing from the margins of the ring to the cord, so as to make the ring indistinct ; this membrane, which is sometimes called fascia 'propria, must also form one of the coverings. The hernia may now either lie in the groin, or pass into the scro- tum, and in either case it will be covered by the condensed cellular membrane, called fascia superficialis. If a patient had worn a truss for some time, all these fascia might be distinctly seen in an operation ; but it is of more im- portance to recollect, that the peritoneum, which forms the .sac, and which, in its natural state, is very thin, would be found very much thickened, and particularly at the neck of the sac; indeed it is occasionally so much thickened, that it may be separated into a dozen layers. But if it were neces- sary to perform an operation for a hernia which had come down only a few hours before, after having cut through the skin and fat, instead of finding distinct fasciae, such as have been described, only a little cellular membrane would be seen covering the sac, and the sac itself would be so thin and trans- parent, that the colour of the gut may be seen shining- through it. The anatomy of the fasciaB in congenital hernia is much the same ; but the sac which is formed by the tunica vaginalis, is generally thin at the lower part, but very strong at the neck. Before describing what are the probable causes of stricture, there are some circumstances to be recollected. To produce strangulation, the gut must be compressed in the whole circle ; strangulation cannot be produced by the muscular fibres which stretch over the gut, for they relax occasionally ; as, for example, when a patient faints. The hole through which the gut is pushed is passive; its diameter is never diminished, but the protruded gut swells and is increased in size. The most common seat of stricture in inguinal hernia is the external ring ; for though we do not see the ring until we have dissected the pait^ atiH we cm feel it, even before the 32 slum is removed, by pushing the finger up along the cord. If the sac has been opened, if the external ring has been cut, and the stricture still continues, what is the cause of stricture : It cannot be produced by the margins of the internal obliqu*: or transversalis muscles, for they will relax. Since we ar<> told by high authority, that the stricture, in such a case, is caused by the internal ring, we cannot deny that it may occa- sionally happen ; but we should be more inclined to say, that the stricture is not caused by the internal ring itself, but by the neck of the sac, which is situated at that part. Our rea- sons for supposing so, are the following : In the dissection of the parts, in their natural or ruptured state, there is no inter- nal ring, until it is made by pushing up the cellular membrane which surrounds the cord ; and even then, if we try its .strength, we find it very weak, and particularly on tjie innev part ; while the neck of the sac is generally so stros|v that \vc might as easily break a circle of whip cord as, tear it- The external ring, and the neck of the sac, may be consid- as the most common scats of stricture ; but there aro vario ties, into the consideration of which it would be impossible to enter at present. There is a species of inguinal hernia called the direct or vcntro inguinal, which has been already mentioned as having the epigastric artery on its pubic side ;() in several other re- spects it differs from the common inguinal hernia. It doe," not come along the inguinal canal, but passes directly through the external ring ; it is not covered by the cremaster or any part of the fascia transversalis, but only by the fascia proprm and superficialis.(6) The peritoneum is' as liable to be thick- ened in this species as in the other. We have seen in opera- tion the sac a quarter of an inch in thickness. This kind of hernia does not take place often, but, in proportion to our limited opportunities, it has occurred to us more frequently than it appears to have done to Mr. Cooper. The dissection of the parts connected with femoral hernir; may now be made. We have already described the fir?' steps of the dissection. It is absolutley necessary that tho limbs be kept forcibly separated from each other., and that the handle of the knife only, should be used in removing the glands, as we are very apt to destroy some of the coi): 1 ions of the fascia?, if we use a sharp knife while the limb? (a) Certainly the iliac side ! (6) By this expression, the student would be led to expect that a scrotal hernia had two coverings from fascise above the aster; while Camper's fascia is the only one lyinbli(uie muscle. ' ' The common expression in London is, that 41 Gimbernat's ligament is the third insertion of Poupart's ligament." Now, it has already been shown, that, after the whole of the tendon of the external oblique has been cut , and, consequently, after that which is generally de- 38 scribed as the third attachment of Poupart's ligament, that there still remains that deep crescentic fascia which has been by us, perhaps erroneously, described as the continuation of the fascia transversalis, which is sufficiently strong to pro- duce strangulation. Now, if Mr. Key's description of Gim- bernat's ligament be correct, here is sufficient proof that it cannot be the part which actually causes the stricture. It would be much better if we were to lay aside the use of Gimbernat's name, for he has no right, from the merits of his publication, to be considered as an authority. Though seme of his remarks are very good, still we cannot have much re* spect for the anatomical acquirements of a man who say ? " Were it not an expansion of the fascia lata, which unites firmly with the bands of the external abdominal ring, and strengthens their junction, they would separate, on the appli- cation of the slightest force, as far as the spine of the ilium;" and in discussing an operation for femoral hernia, by Baudoti, in the Hotel Dieu, he says, " The spermatic artery, when di- vided within the abdomen^ occasions a haemorrhage very diffi- cult to stop." The operation of Gimbernat appears to have been suggest- ed by speculations upon the view of the parts in their natural state, and not from any observation of the difficulties which embarrass the surgeon in his operation. Surely there cannot be any thing worthy of admiration in his manner of operating, for he most awkwardly, with both his- hands, introduces his directory and bistoury on the gitte"of the sac next the pubep. and runs them inwards, so^a^'to cut up the attachment of the Poupart ligament to t.rre os pubis. He does not describe the danger which the obturator artery would be in frcm this cut, but he warns us to take care that we do not wound the uterus or bladder : by this last advice he clearly shows to what a depth he would pass his knife, and what a confused idea he had of the parts. We may say in conclusion, that although the study of the anatomy of the groin must always be considered as a princi- pal part of the surgical education of a student, still, after he has made himself master, not only of the simple anatomy, but also of the confused descriptions of the parts which have been given at various times, he has much to learn to make himself competent to undertake an operation for femoral hernia. Those who have seen many operations for femoral hernia, must allow, that they hardly ever saw the appearances exact- ly similar in two cases. The knowledge of all the circum- stances is only to be attained by watching the operations of a skilful surgeon; and by examining the diseased parts; and though we will confess that it is very difficult fora student. to 39 get such opportunities, still we think, that it is in his power, while prosecuting his studies in London, to derive much more benefit by examining the preparations of hernia which are to be found in Anatomical Museums, and by paying attention to the history of cases given by a surgeon well acquainted with anatomy, than by endeavoring to follow all the various de- scriptions which have been given of the fascia." I trust that what I have said in this paper will not be mis- construed, for -no one can have a stronger conviction than 3 have, of the absolute necessity of attending to the natural anatomy of the parts connected with hernia. But while stu- dents, in consequence of reading what they consider the best authors on this subject, are led to think only of the direction in which the stricture is to be divided, so as to avoid wound- Ing t^e epigastric artery or the spermatic cord, they are, for these supposed dangers, (for there is hardly a case on record of the wound of either of those parts,) neglecting the conside- j-ation of questions which will be forced upon them in almost every f operation. For instance, the changes which take place in the parts superficialto the sac, and in the sac itself, the difficulty of recognising the true peritoneal sac, the .stricture produced by the neck of the sac, the danger of re- ducing the serum in the sac, and leaving the intestine still, .strangulated, those changes which take piece in the gui producing strangulation, the difference between strangula- tion and incarceration, the circumstances which render an artificial anus necessary, or what is to be done for the re- newal of the course of the faeces. Some examples illustra- tive of these questions, will be found in a paper written by me, in the sixth number of the Quarterly Journal of Foreign Medicine and Surgery, February, 1820. The books on her- nia I need hardly point out; but prejudice in favour of lh<- history of operations in which I have personally assisted. 'Mids mo to direct the student's attention particularly to the vases which are related by Mr. Charles Bell. I shall now proceed to describe the dissection of the viscera of the abdomen, which I have already said ought to be made before the young student can attend, with advantage, to the t vi' hernia. . 40 FIRST VIEW OF THE VISCERA OF THE ABDOMEN The first general view of the viscera may be taken from the body on which the muscles have been dissected. Before exposing the cavity of the abdomen, the student should attend to those arbitrary divisions which have been called the Regions of the Abdomen. To mark these, one line should be drawn across the abdomen, between the most prominent parts of the cartilages of the ribs, and another be- tween the superior spinous processes of the ilia. These lines; will divide the belly into three parts, each of which is subdi- vided. The space above the middle line includes the epi- gastric and the right and left hypochondriac regions, thf cartilages of the ribs form the lateral boundaries of the epi- gastric region, the centre and upper part of which is often called scrobiculus cordis. If we take the umbilicus for a . centre, and describe a circle, the radius of which extends to the upper and lower line, we shall include in it the umbilical region; on each side of which is the iliac region ; and nearer to the spine, and on the same parallel, are the lumbar re- gions, or the loins. Below the lower line we have, in the middle, the hypogastric, or pubic region, and on each side of this, there is an inguinal region. In making the dissection of tha abdomen, to discover the cause of death, we must have a regard to what will least dis- figure the body; the method of doing this will be pointed out, afterwards ; but in the present dissection, the muscles must be cut^ though, in the manner best suited for giving a gene- ral idea of the anatomy. Before cutting through the peritoneum, the trans versalis. on the right side, may be divided, so as to expose the sur- face of the peritoneum ; then, by insinuating the finger be- tween the muscle and the peritoneum, and by carrying it to- wards the spine, we shall be able to form some idea of what is meant by the common expression, " that the viscera are behind the peritoneum," in doing this, we may observe, that the surface of the peritoneum in union with the muscles, is of a cellular texture : we shall afterwards find that the inner surface is smooth and serous. 41 'NY e may now expose the cavity of the abdomen, by making an incision on the left side of the linea alba, from the ensiform cartilage to the umbilicus, and then from the umbilicus to the spine of the ilium, on each side: the lower flap may be laid over the pubes. The view of the viscera now before us is most perplexing-, and has no resemblance to their situation in the living- body ; indeed it is impossible to put any one turn of the intestines into the relation which it had to any other, while it was sup- ported by the natural and uniform pressure of the abdominal muscles in the living -body. If we consider what the condi- tion of the viscera must be, when compressed by the respira- tory muscles, or when the body is in full action, and the viscera are at the same time, by their peculiar peristaltic ac- tion, propelling their contents from the stomach to the rec- tum, we may form some idea of what incorrect notions we should have of the course of a wound, or the seat of disease, were we to take our impressions from the present state of the viscera, which we see falling into almost inextricable -confusion as soon as the muscles are cut through. These* observations I have thought it necessary to make, because I very frequently find students teasing themselves with what they call " relative position ;" not only forgetting that the position of. the parts is changed in consequence of death, but that the state of all the viscera, from the oesopha- gus to the rectum, varies, according to their being full or empty. We may now proceed to examine the common appearance of the parts within the abdomen. When the abdomen is first opened, a small portion of the liver will be seen to project from under the ribs ; part of the great arch of the stomach will generally occupy the centre and left side. If the body be that of a young person, and if there have been no disease in the abdomen, the great omen- turn or epiploon will extend from the stomach over the small intestines. The great intestine, or colon, if distended, wiJi lie very close to the stomach ; it may perhaps be seen under the transparent omen-turn. If we lift up the omentum from below, and turn it over the margin of the ribs, we shall then see the small intestines and the colon. If the bladder be dis- tended, a small portion of it will be visible. Before examining the several viscera, we should attend to the inflections of the peritoneum,. It is difficult for a young- student to understand the relation which the peritoneum has to the viscera ; for when the abdomen is laid open, he is apt. to imagine that the intestines are contained within the incrn- , but it is not so : for if we trace the peritoneum 42 the inside of the transversalis muscle, we may strip It from the back of the colon ; thus proving, that this intestine i not surrounded by it. By a little care, we may show that the membrane has the same relation to the other viscera* and to the muscles of the abdomen. Hence, the peritoneum lias been described as a loose bag, the internal surface of which has the character of a serous membrane, which, being- interposed between the muscles and the viscera, adheres to each through the medium of its external cellular surface. It is not easy to show all the connections of the peritoneum, for it not only forms a covering to most of the viscera, but also holds them in a certain relative position to each other; whence, some parts of it have been described as ligaments, as, of the liver, spleen, colon, small intestines, &c. A stu- dent may form a general idea of the inflections of the perito- neum, by tracing it, from the inside of the right transversalis muscle over the colon, to form the lateral part of the meso- oolon, then to the small intestines, to form the mesentery, and from them to the sigmoid flexure of the colon and to the abdominal muscles of the left side, from which it may again* be traced towards the right side. It is more difficult* to trace the peritoneum from above downwards. We may begin to trace it at the diaphragm ; from which it maybe seen to pass off to the liver. From the liver, we may trace it, under the name of the lesser omentum, to the stomach, then, from the stomach to the arch of the colon, as the great omentum. If we hold up the colon, we shall be able to trace the perito- neum, from the surface of the gut towards the spine, as the mesocolon, or, as it is sometimes called, " the ligament ol" the colon," and which is needlessly divided into two portions, called " right and left mesocolon." From the lower part of the mesocolon, we may trace it to form the mesentery of the small intestines. From this it passes down to the rectum, and here it is called "the mesorectum." In the female, we may trace the membrane to the uterus, to form the ligament* of this viscus, and then, as the plica semilunaris, to the blad- der ; from which, as in man, we may again trace the perito- neum to the muscles of the abdomen, and, so, round to where we began.* * I shall here enumerate certain parts of the peritoneum, whicli have not yet been mentioned ; the student will have no difficulty in discovering them, without any further de- scription ligamentum dextrum venlriculi; the vinculum oeso- phagi ; vinculum inter cesophagum et lienem ; plica renalis et "ctpsularis ; plica d rene ad colon ; plica duodeno renalis ; plica *'pa*ico wnak. When the lower part of the muscles of the 43 The principal difficulty in following the inflections of the peritoneum, is owing to the great, or gastro-colic, omentum, the lamina of which have been always matter of great an- noyance to the student. If the omentum be not thickened by disease, it will be seen running from the stomach down nearly to the pelvis; and if it be lifted up, it will be found attached to the arch of the colon. If the colon had been far removed from the stomach, then the omentum would have appeared more simple ; for in this case, we might have traced one layer from the upper, and another from the lower surface of the stomach, to the corresponding* parts of the colon; but as the colon lies close upon the stomach, and as the omentum is of a great length, it is necessarily reflected back upon itself to pass to the colon, so that below the line of the colon, the two layers of the omentum must be doubled, and hence it may be said that the loose portion of the omentum which covers the small intestines is formed of four laminae. * The young student is not less puzzled by the descriptions which are generally given of the bag of the omentum and the foramen of Winslow, perhaps the difficulty will be les- sened if he examines the parts in the following manner: In pulling the stomach down from the liver, the lesser omentum or mesogastrium will be seen : and in doing this, the vessels which are passing to and from the liver may be seen or felt ; these vessels are surrounded by the peritoneum -and a portion of cellular membrane, and as this was de- scribed by Glisson as bearing some resemblance to a capsule, it has been called the capsule of Glisson. If the finger be put under these vessels on the right side, it will pass under the ligamentum hepatico duodenale, and into the foramen of Winslow, which is the opening of the great bag of the omen- turn, the boundaries of which may be traced in the following manner : If we push the finger towards the left side, it will be seen under the omentum minus ; if farther, it will pass abdomen are cut from the umbilicus to the ossa ilii, three lines will be seen on the peritoneum, the central one, from the fundus of the bladder to the umbilicus, is formed by the part which in the foetus was called "urachus;" and the two lateral lines are formed by the remains of the umbilical arteries. These parts are external, but adhere so closely to the peritoneum in the adult, as to appear to be produced by a thickening of the membrane. * The portion of the great omentum which runs towards the usseumis called " omentum caeci ;" this is quite different from .the appendices epiploicce, which are found on the colon, and. which are sometimes called " omentults intestini crassi." 44 'under the stomach; if we try and push it backwards, it \vjji be stopped by the pancreas and the parts lying on the spine ; if w r e pass it'in a direction downwards, it will be obstructed by the mesocolon, and if upwards, by the liver ; but if there be no adhesions formed, we shall be able to pass it up be- t ween the stomach and colon, into the space between the tluplicature of the omentum, which, in a young body, may be distended so as to appear like a bag, by blowing with a pair uf bellows into the foramen of Winslow. When the omentum is dissected from the stomach and co- lon, the viscera will appear very confused ; but by a little management, the parts may be unravelled. Look in the right iliac region for the termination of the small " intestine (the ileon) in the great intestine (the colon;) make a small opening in the ileon, about six inches from the colon; intro- duce a blow-pipe, and blow towards the colon : the colon being distended, will be seen with its membrane (mesocolou^ to form a natural division in the abdomen, all the small in- testines being below, and the stomach, &c. above it. When the colon is distended, we can understand the terms which ure given to its several parts, viz. caput ; ccecum ; processuv rcrmiformis; ascending part of the arch; transverse part of t ke arch ; descending part ; and si gmoid flexure. The small intestines are seen lying in a confused mass within the embrace of the colon : to unravel them, the blow- pipe should again be put into the lower part of the ileon; and then by blowing upwards, the whole of the intestinum tenue, or small intestines, will be distended. The upper part, which will be now easily found, should be tied just before it passes under the mesocolon. The small intestines are generally divided into five part?, three of wiiich are given to the upper portion, which is called jejunum, and two to the lower, viz. the ileon. The arteries seen in this view, are all branches either of the superior or inferior mesenteric. The email intestines may now be re- moved from the mesentery, by cutting all that is between the 3igature on the ileon, and that on the jejunum. We may now examine the viscera above the line of the colon. If the blow-pipe be introduced into the remaining- part of the jejunum, the air will distend the duodenum and the stomach. The colon is to be pulled downwards, and is then to be removed by dissecting away the mesoeolon from the parts below it; by doing so, we shaH get a view .of the liver, the stomach and spleen, the dmodenum and pan- creas. If we pull down the stomach, we shall see the oeso- phagus coming through the diaphragm, and entering the fiac orifice of the stomach ; upon its left side we e&ul see- 45 Oie spleen, attached by a set of small vessels. Tracing the arch of the stomach downwards, we come to the pylorus ; by taking this between the finger and thumb, we shall discover a thickening of the coats of the stomach, which forms the sphincter of the pylorus, improperly called a valve. Imme- diately below the sphincter, is the beginning of the duode- num; this gut appears generally so large, as, from its size, to entitle it to the name of ventriculus secundus ; it may be traced up towards the gall bladder, and then, taking an irregular turn upon itself, it passes towards the left side, across the -spine; at the point where it is passing over the spine, we see that is bound down by the mesocolon, and here we may also observe, that the peritoneum does not so entirely cover it as it does the other intestines. The most important parts which we have to attend to in the duodenum are the ducts which pass into it. The edge of the liver may now be held up by an assistant, that we may haVe a view oY the gall bladder, and of those vessels and ducts which are -contained within the capsule of Glisson. On holding up the liver in this manner, we shall understand the derivation of the name, porta, for the part of the liver into which those vessels are passing, has something of the form of a gateway; whence the name vena portce has been given to the principal vessel of the liver. When the arteries and veins are injected, there will be no difficulty in discovering the several parts ; but even in the umnjected state, they will be easily found, by merely taking off the cellular membrane investing them. The vessel on the left side will be the hepatic artery ; the large vessel in the middle is the vena portae ; the ductus communis choledo- chus is on the right side, and will be known by its dusky yel- low colour. It will be easy to trace from this, the ductus Cysticus ; into which such a hole is to be made as will admit a blow-pipe : by. blowing towards the liver, the gall bladder will be distended ; and by blowing in the other direction, we shall distend the hepatic ducts, and the ductus communis choledochus: by which the dissection will be facilitated. Perhaps a better mode of distending these parts will be, to make a very small puncture into the upper part of the gall bladder; from which the bladder and ah 1 the ducts maybe a\ once injected or filled with air. The cellular membrane is now to be carefully taken of!' from the pancreas, so as to expose the duct, which is like a vein, but of a whiter colour; it runs into the duodenum, close to the ductus communis choledochus. A second duct of the ea? will be generally found coming from that part of the 46 irfand which is called the head, and which adheres closely to the duodenum. Before separating the liver from the diaphragm, the liga- ments should' be observed: 1st. the round ligament, or the remains of the umbilical vein ; 2d. the broad, or suspensory ligament formed by the peritoneum passing from the mus- cles of the abdomen, and from the diaphragm; 3d. the coro- nary ligament, being the attachment of the liver to the dia- phragm, through the medium of the peritoneum; and 4th and 5th, the two lateral ligaments, which are only the right and left extremities of the coronary ligament. In separating the viscera from the abdomen, if we cut through the round and suspensary ligaments, the liver will be retained only by the coronary ligament ; in cutting this last ligament, we must also divide the venas cavse hepatica?. In removing- the stomach, the (esophagus must be pulled down ; but it should be tied with a double ligature before it is cut. The pancreas, &c. will also be easily separated by cutting- through a Tew vessels, and a little cellular membrane. The viscera may be put into water, for future examination. We may now show the muscular fibres of the diaphragm, by taking oif the peritoneum which covers it ; but in doin and abdomen ; it is concave downward and convex upward -, the middle of it, on each side, reaches as high within th thorax as the leyel of the fourth rib. The diaphragm is generally described as consisting of two muscles and an intermediate tendon. THE SUPERIOR OR GREATER MUSCLE OF THE DIAPHRAGM. OR. By distinct fleshy fibres : 1 . from the cartilago ensifor- mis ; 2. from the cartilages of the seventh, and of all the in- ferior ribs on both sides, and ligamentum arcuatum. IN. From these origins, the fibres run radiated from the circumference to the centre of the septum, and terminate in a cordiform tendon, which forms the middle of the diaphragm, and in which the fibres from the opposite sides are inserted and interlaced. To the right of this tendinous centre there is a perforation for transmitting the vena cava. THE INFERIOR OR LESSER MUSCLE OF THE DIAPHRAGM, OR. The second, third, and fourth lumbar vertebrae, by sev- eral tendinous heads, of which the central and longest are called the crura. (Between the crura, the aorta and tho- racic duct pass: and, on the outside of these, the great sym- pathetic nerves and branches of the vena azygos perforate the shorter heads.) The fibres run upwards, and form, in the middle, two fleshy columns, which decussate, and leave an oval space between them for the passage of the oesopha- gus and eighth pair of nerves. IN. The back part of the central tendon of the diaphragm, USE. The diaphragm is the principal muscle of respira* tion : when it is in action, the fibres bring the septum to- wards a plane, by which the cavity of the thorax is enlarged ; when relaxed, it is pressed by the abdominal muscles, which, acting through the viscera, thrust it up, and compress tin* Imgs. 48 QUADRATUS LUMBORUM. OR. From the posterior pai^ of the spine of the os ilium. IN. Into the transverse processes of all the lumbar verte- brae ; into the last rib near the spine ; and, by a small tendon, into the side of thelasi vertebra of the back. USE. To move the loins to one side ; to pull down the last rib; and when the -muscles of both sides act, "to bend the loins forward. PSOAS PARVUS. On. The sides of the two upper verte- brae of the loins. Sends off a small long tendon, which ends thin and flat, and is IN. Into the iliac fascia and Poupart's ligament. USE. To strengthen the insertion of the abdominal mus- des, and prevent their yielding in the straining of the mus- cles of the trunk. This muscle is often wanting. PSQAS MAGNUS. OR. 1. The body, and transverse pro- cess of the last vertebra of the back ; 2. from all those of the loins. IN. The trochanter minor of the thigh bone ; and into that bone a little below the trochanter. USE. To bend the thigh forwards, or, when the inferior extremity is fixed, to assist in bringing the body forward. ILIACUS INTERNUS. OR. 1. The transverse process of the last vertebra of the loins: 2. all the inner lip of the spine f the ilium ; 3. the edge of that bone, between its anterior superior spinous process and the acetabulum; 4. from most of the hollow part of the ilium. It joins with the psoas mag-- nus, where it begins to become tendinous, and is IN. Into the lesser trochanter. USE. To assist the psoas magnus. DISSECTION OF THE ARTERIES dJYD VEWS OF THE VISCERA. IP the student does not intend to examine the minutr- Structure of those viscera which he has removed from the- "body* he should now proceed to dissect the muscleB of fte- 19 ? high, or of the perineum, if it be a male body. But before describing those parts, I shall point out the method of dis- secting the vessels of the abdomen, and the manner of show- ing the minute anatomy of the several viscera. The arteries which supply the viscera are very easily ar- ranged ; indeed, the whole anatomy of them is BO simple, that it is almost a pity to sacrifice the abdomen for the arte- ries only; we should therefore endeavour, at the same time* to make a dissection of the venous system. The method of injecting the vessels will depend upon th/- manner in which the thorax is to be dissected. If the subject be young, and if it be intended to make u preparation of the arteries, then those of the abdomen aro to be filled, in common with the others, from the arch of the aorta ; but> in the usual dissection, where the parts are not to be preserved, the arteries may be injected after the mus- cles of the. abdomen have been dissected. To do this neatly, we should tie the aorta above the diaphragm, and also one bi the iliac arteries at its origin from the aorta, and then put a pipe into the other common iliac, as close to the aorta as possible, so that there may be enough of the artery left to enable us to put a tube into it afterwards for the injection of the lower extremity. When we inject the viscera of an adult subject at the same time with the vessels of the upper part of the body, from the arch of the aorta, it can hardly be expected that the vessels of the viscera, or of the limbs, will be fully dis- tended, for the size and dilatability of the vessels of the ab- domen will take off the force of the syringe from the smaller vessels. The objection to introducing the pipe into the aorta, above the diaphragm, and injecting downwards, is, that, to manage the pipe properly, a great part of the thorax must be destroyed. The best composition for the injection of the vessels of the viscera, is a strong solution of glue, coloured with red lead, or an injection made of tallow and turpentine varnish. As both of these compositions must be used while warm, it is necessary to heat the vessels of the abdomen; this is most easily done by making an opening into the intestines, and injecting a quantity of hot water into them. The veins must be injected- before the intestines are exa- mined; and as there are no valves in them, the injection will be easily made. The veins of the liver may be injected from the ramifica- tions of those in the mesentery ; or the veins of the intestines may be injected from the trunk of the vena portae. To find th? vena porta* as it enters the liver, the stomach should br E 50 held down, and the smaller omcntum cleared away fr om b> twixt the stomach and liver : the vein is then found (covered in part witli cellular substance) running obliquely across the spine, and parallel to the biliary duct. If we be uncertain of its situation, the substance of the liver may be pressed gently with the hand, or the blood urged alon<* the veins of the intestines, and then the vena portoe will rise from the confusion, as a large dark blue vein. But to understand the course of the veins which form the vena portae, and at the same time not to endanger the cutting of them, we should inject them by putting a pipe into the ileo colic vein. This branch is easily found, as it has its name from being subservient to the caput coli and that part of the intestinum ileon which joins the colon ; it is only ne- cessary, therefore,, to fold back the small intestines from the right os ilium, and to expose the caput coli, and to follow up the veins till they have assumed a size large enough to ad- mit the tube. After puncturing the vein, and fixing the tube, there should be a ligature put upon the part of the vessel behind the tube, that the injection may be prevented from coming round and escaping. Before throwing in the injection, the veins should be repeatedly syringed with warm water. The injection may be made to run more minutely into the vessels of the intestines by pressing gently upon the trunk of the vena portae. As the venos cavae hepatic may be filled by a successful injection, the vena cava should be tied just above the dia- phragm. The vena cava itself should not be injected, for its branches can be easily traced without their being filled. When they are injected at the same time with the other vessels of the abdomen, they encumber the dissector very much ; if we wish to fill them, we should put a pipe into the i'liac or femoral vein. When all the vessels are injected, the small intestines should be removed, and the colon blown up according to the description already given in the first dissection of the ab- domen. All those arteries which are seen on the part of the mesentery which has been left, and also- on the right side and middle of the mesocolon, are branches of the superior mesenteric artery ; while those which run towards the sigmoid flexure and rectum, are from the inferior mesen- teric. The dissection is to be begun with the loose mesentery, by dissecting off the peritoneal coat and fat from the ves- sels. These arteries in the mesentery have no appropriated names, but compose one set of innumerable branches, form- ing-, before they reach the email intestines, frequent 51 moses and arches, by which the capacity of the branches combined, must be wonderfully increased in proportion to that of the single trunk from which they arise. From the UPPER MESENTERIC ARTERY, upon the right side, three branches are given off to the colon. The ARTERIA ILIO-COLICA ; whose ramifications connect the branches which go to the small intestines, with those which go to the colon. It runs down to the caput coli, and last turns of the ileon. Its branches upon the small intes- tine inosculate with those branches of the superior mesenteric which are distributed to the small intestines in general; ancL upon the great intestine, it inosculates with the second colic branch of the superior mesenteric artery, viz. The COLIC A DEXTRA; which will be found running from the root of the superior mesenteric artery across towards the right side of the colon, where it begins to rise over the kidney, inosculating freely with the last branch, and up- wards with The COLICA MEDIA. This branch goes directly upward.-' from the trunk of the upper mesenteric artery, as it comes out from under the mesocolon. After running a little way upon the mesocolon, it divides ; and one of the division* going towards the right side, makes a large circle upon th- mesocolon, and forms a great inosculation with the right colic artery ; while the other division, going towards the left .side, makes such another sweep, and joins with the left colic, which is a branch from the lower mesenteric artery. These two branches of the median colic artery give off nu- merous ramifications, which supply a great extent of the middle part of the colon. The INFERIOR MESENTERIC. The branches of the inferior mesenteric artery are easily found. The dissection may be backwards, from the hsembrrhoidal artery lying upon the back and upper part of the rectum. Proceeding up along the gut, numerous branches are found distributed to that part of the colon which forms the sigmcid flexure. These are derived from the uppermost brancli of the lower mesen- 1 eric, and as it supplies the left side of the colon, it is called the COLICA SINISTRA; it communicates with the median colic brancli of the upper mesenteric artery, and completes a great circle of inosculations, reaching all the length of thu intestinal canal.* *In the dissection of the lower mesenteric artery, its root is found entangled by the nerves of the lower mesenteric plexus, which is formed by branches from the sympathetic. widby branches from the superior mesenteric plexus, and 52 OF THE ACCOMPANYING VEINS SEEN JN THIS VIEW OP THF INTESTINES. The branches of the veins run here in com- pany with the arteries, however different they may be in the direction of their trunks. Therefore the names and distri- bution of the one set of vessels being known, the other must be known also : for all vessels ehould be named from the parts to which they are distributed, and not from the trunks from which they are sent off; their distribution being con- stant, their derivation irregular. The veins, as seen in this view of the parts, preserve n uniform course; their varieties consisting only in the direc- tion of the trunks in which they are gathered to form the vena portee. Returning, then, upon the demonstration of the arteries The hicmorrhoidal vein, rising from the back of the recturm rway be easily found ; the vena coUca sinistra, coming fron i. the left part of the colon, is united to the last; the vena colica media, the vena colica dextra, and the vena ilio colica^ being united, return the blood from the arch of the colon ; while one great branch, which is promiscuously divided among the small intestines, carries back their blood to the vena port as These veins will be further traced in the next view of the intestines. The dissection of the cceliac artery, of the trunk of the vena portae, of the arteries and veins of the stomach, and of the corresponding arteries of the liver, gall-ducts, and pancreas, may now be made. Separate the arch of the colon from the stomach, and lay It down in the manner described in the first dissection. There is now much difficult dissection. The stomach will be seen lying under the projecting liver; the spleen, towards the left end of the stomach ; the pancreas will be found lying directly across the aorta, reaching from the spleen to the duodenum, and involved in the root of the me- jsocolon. The cceliac artery supplies all the parts lying in the upper division of the belly, above the mesocolon. It is the second artery of the abdominal aorta, coming off at the point where* the great artery seems to be extricating itself from the dia- phragm. It rises directly from the aorta, as a short trunk, \vlrich divides quickly into branches. The best way to dissect this artery, is, to distend the stomach slightly, and then to pull it down, so that we may threat coslic plexus. The lower mesenteric plexus, surround- ing- the trunk of the artery, sends branches out along the to the left side of the colon, and to the rectum. ct the lesser "omentum from betwixt it and the liver, The artery will then be found, dividing at once into many branches ; and as they depart in different directions from on< - point, as from a centre, the trunk is called the axis arteriw cceliacce. The ARTERIA CORONARIA VENTRICULI Will be foWld g011]g off towards the left side, and spreading largely over the up- per part of the stomach. If, in dissecting it where it goes off from the trunk of the cceliae, it is found to be larger than the Other branches, it may be expected to send a branch to the liver, and we should then be more cautious in dissecting in that direction ; for the vessel will pass to the right, and then upwards, till it be lost in the fossa ductus venosi. When, there is no branch sent to the liver, it holds its course to the left or superior orifice of the stomach. Here it divides into two brandies : one of which encircles the cardiac orifice, and inosculates with the gastro-epiploic artery above the spleen ; the other runs along the lesser arch of the stomach, sends a branch over the side of the stomach, and, continuing its course, inosculates with the pylorica, or coronaria dextra. \ In tracing these branches upon the lesser curvature of the stomach, we shall find several nerves which are branches of the eighth pair, or par vagum. The ARTERIA SPLENIC A arises from the trunk, or axis of the coeliac artery. It passes under the stomach, and along the border of the pancreas, where it gives off the pancreati- cae parvaa. Continuing its serpentine course, it gives the vasa brevia to the stomach, and small branches to the meso- colon. When it reaches the spleen, it makes a curve in its bosom, and enters it in several branches. It ?ends off from its branches in the spleen, a considerable branch to the stomach, which, inosculating with the right gastro-epiploic artery, is called the gastro-epiploica sinistra. The ARTERIA HEPATIC A runs in a direction opposite to the splenic artery, towards the right side. . After having run some way in the direction of the trunk of the vena portae, it divides, nearly at the same place> into four branches, which spread over the trunk of the vena portae. The first branch .sent off, is the arteria gastro-epiploica dextra, so named from its chief branch; or sometimes called the duodeno-gastriea, from that branch of it which goes to the duodenum. This artery, descending under the pylorus to gain the great cur- vature of the stomach, with its accompanying vein, catches the eye while the viscera are yet entire. It is seen beauti- fully distributed to the-stomach and omentum ; and reaching the left and obtuse end of the stomach, it inosculates largel}* -.vith the splenic artery, As this gastro-epiploic artery runs 54 across the under side of the duodenum, it gives oft 4 the pan- creatico duodenalis, which runs down the intestine, ant rfends a considerable branch along- the pancreas. The hepatic artery, after sending- off the gastro-epiploica ilextra, divides into the right and left hepatic branches. Prom the left hepatic, the coronaria dextra is sent off, which, turning backwards, spreads its branches upon the pyloric end of the stomach, inosculating with the proper coronary of the superior orifice, and with the pyloric arteries, which are numerous and important twigs from the surroundingjgreater arteries; the coronary sometimes comes off from the trunk of the hepatic artery, climbing upon the vena ports?, enters the liver, ceid,, separating into branches, is distributed within the liver, to the whole of the left kfbe, the lobe of Spigelius, and part of the right lobe. The right hepatic artery, passing under the hepatic duct of the liver, is distributed to the right lobe of the liver, and gives a branch which is called the cys- tica, to the gall-bladder. In dissecting the root of the coeliac artery, and part of the aorta, betwixt it and the superior mesenteric artery, we see the ccelic plexus, which is formed by branches from the se- milunar ganglions of the sympathetic nerves, and from the eighth pair, which is principally distributed to the stomach. Prom this plexus an immense number of smaller nerves arc* sent out, forming lesser plexuses, along the mesentery, and to the duodenum, liver, spleen, &c. Of the VEN^A. PORT.SE. The vena portse is formed by the union of the veins from the intestinal canal, and from those * of the spleen and pancreas. Near the liver, these veins are collected from three great branches, corresponding to the cosliac, upper and lower mesenteric arteries. The trunk of the vena portae lies obliquely across the spine, upon the body, and under the head of the pancreas. The branch answering to the cceliac, is the splenic vein. It forms one of the great divisions of the vena portse, as it gathers the blood from the spleen, stomach, pancreas, and omentum; it passes from the left towards the right side. The veins coming up from the lower part of the belly, cor- responding to the mesenteric arteries, are the mesenterica major, and the mesenterica minor. All the veins from the mesentery, and from one half of the colon, meeting together, form the first of these; which, from its size, is the most im- portant vein of the intestines. Its branches run in company with the extremities of the superior mesenteric artery, which pass from the duodenum along tne track of the intestines. to the middle of the colon. This vein joins the trunk of the venaportee. 55 The vena mesenterica minor carries back the blood fron> the left side of the colon, and from the rectum, accompanying the lower mesenteric artery in its whole course. From the branch which mounts up upon the back of the rectum, it has been called the hcemorrhoidea interna. This vein joins sometimes with the splenica ; more commonly with the me- senterica major. As the great mesenteric trunk goes up under the duodenum, it receives the veins of the pyloric orifice, and those answering to the pancreatico-duodenal ar- tery. As the trunk of the vena portse runs across the spine towards the liver, it receives the veins from the right side of the duodenum, and lesser arch of the stomach, answering to the lesser coronary, or right coronary of the stomach ; then mounting obliquely upwards and towards the right side, it enters the porta of the liver, and dividing into two great branches, forms the great binus of the liver. As the vena portse approaches the liver, it runs parallel with, and between the ducts and the hepatic artery. They are here included in one sheath of cellular substance, viz. the capsule of Glisson. The vena portse may be considered as a vein which performs the office of an artery in the liver,* by distributing in it that blood which it collects from the ar- teries of the intestines. But the proper veins of the liver, the venae cavie- hepaticse, return their blood directly to then heart. These, in their extremities, are distributed much like the vena portae ; but upon dissecting the under surface of the liver, they are found to run up towards the attachment of the liver to the diaphragm, and to enter into the inferior cava near the heart. In dissecting these veins, there is much cellular substance to be cleared away ; and it is not easy, if the injection be at all brittle, to dissect upon their thin coats without cutting them, or breaking the injection. The arteries which run to the kidneys, and the spermatic-, may now be seen by lifting up the mesocolon ; but in order to show them more distinctly, the chylopoetic viscera should be removed, and then we shall have a more distinct view of the trunk of the aorta, and the large branches going off from it. In order to remove the viscera, we- should first cut through the cceliac artery at the part where it is dividing into its branches, and through the superior and inferior mesenteric arteries ; leaving small portions of each, by which we may recognise them. The oesophagus is then to be divided ; and * I found it in the camel which was dissected in Windmill Street, in April, 1821, to be as distinctly muscular as the oesophagus,. 56 uy separating the liver from the diaphragm, the whole of the viscera above the mesocolon may be removed. In lifting the colon, we must take care that we do not cut through the arteries to the kidneys, or the spermatic vessels ; indeed, t.hese vessels ought to be fully exposed before the colon is raised, as the spermatic arteries will be much endangered if we pull the caput coli and sigmoid. flexure rudely up. A portion of the rectum should be left. We may now observe, that the aorta passes between the crura of the diaphragm, entering the abdomen rather on the left side of the spine, but, that as it passes down, it comes more to the middle, the vena cava is seen to be distinctly upon the right side of the spine, and continuing in the same line until it passes through the perforation in the tendon of the diaphragm. We should now turn our attention to the kidneys. -We see one on each side of the spine, and lying on the last ribs, the right being rather lower than the left. In a young body, we see a fatty mass lying on the upper part of the kidney, this decreases in size in the adult; it is called the renal cap- sule, or glandult atrabiliaris besides this, there is generally a quantity of fat surrounding the kidney. From the bosom and lower part of the kidney/ we see the ureter, or duct, passing towards the pelvis ; which, with the arteries run- ning from the aorta to the kidneys, may be easily exposed, by merely removing the cellular membrane. The only thing which tends to make the dissection of t)*e vessels difficult, is the number of nerves which encircle the several branches. We ought not to dissect too closely between the right cms of the diaphragm and the aorta, for here is the thoracic duct, which, with a little care, may be preserved, so that we may either inject it, or fill it with air by the blow-pipe; but though a large vessel, it is difficult to find it, on account of its being empty and its coats transparent. It is sometimes pos- sible to fill it, by throwing air or mercury into the substance of one of the lymphatic glands which lie by the side of the jumbar vertebrae. The arteries seen when the cellular membrane, &c. is re-- moved, will be- the phrenic arteries, which are sometimes branches of the eoslic; the trunk of the coalic : the superior mesenteric artery ; the capsulares, which sometimes come from the emulgents ; the renal or emulgents ; the right sper- matic, from the aorta ; the left spermetic, often from the left emulgent; and, lastly, the inferior mesenteric, all these are seen coming from the forepart of the aorta : but besides these, a regular set of vessels pass into the spaces between the vertebrae, these are the lumbar. There are also gene- xally some, small irregular branches to the glands. &c* 57 The aorta, passing down towards the pelvis, divides into two great branches The COMMON ILIACS ; and from these, all the arteries of the pelvis are given, except those to the rectum from the inferior mesenteric, and to the uterus, in the female, from the spermatic. Before examining- the arteries farther, we may observe how the vena cava is formed. The veins of the stomach and intestines, the pancreas and the spleen, we have already traced into the vena portee. We see the great vena cava formed principally by the veins from the lower extremities ; but we shall find that the veins of the kidney and the testicle also run into it. We may observe that the left emulgent vein, as it crosses over the aorta, is much longer than the right ; and that the left spermatic vein almost always joins the left emulgent, whiln the right passes direct into the vena cava. The cava occasionally receives some branches from the lumbar veins ; it then passes up towards the diaphragm, sometimes it passes through a hole of the liver, which must be recollected in removing this viscus; but it is more; Commonly covered by a portion of the liver, which forms an arch : just as it is passing through the diaphragm it receives t he venos cavse hepaticro, and the phrenic veins. TABLE OF THE ARTERIES WHICH ARE SENT OFF FROM THE ABDOMINAL AORTA, L PIIRENICA DEXTRA. II. PHRENICA SINISTRA. III. CCELIACA. IV. MESENTERICA SUPERIOR, V. MESENTERICA INFERIOR. VI. CAPSULARES. VII. RENALIS DEXTRA ETRENALIS SINISTRA. VIII. SPERMATICA DEXTRA ET SPERMATICA SINISTRA. IX. SMALL BRANCHES WHICH GO TO TIIK URETERS, FAT, &c. X. LUMBALES. T. & II. PIIRENICA DEXTRA & PHRENICA SINIS- TRA, give branches to the Diaphragm, inosculating with the Mammariss Interme, and also irregultu 58 branches to the Pancreas, to the Membranes of the Liver, and to the Spleen. III. C (ELI AC A, from which come, 1. CORONARIA VENTRI- CULI SUPERIOR ; 2. HEPATICA; 3. SPLENICA. From the CORONARIA VENTRICULI SUPERIOR there come two sets of branches, viz. a superior division to the stomach, to the (Esophagus, to the Diaphragm and Omentum Minus ; and the inferior division, to the Lesser Curvature of the Stomach, and the Pylorica Superior. From the HEPATICA. 1st. The Hepatica Dextra. which gives off the Cystica 2d. Hepatica Sinistnt. Sometimes, 3d. Coronaria Dextra 4th. Duodenu Gastrica. The lesser branches which corne frdm these are called Pylorica Inferior Pancreafica Duo- denalis Gestro Epiploica Dextra JPancreaticcc and Epiploicce. From the SPLENICA. Pancreaticce 'Castro Epi- ploica Sinistra and Vasa Brevia. IV. MESENTERICA SUPERIOR. Distributed to UK; whole of the Small Intestines ; and gives oft' to the Great Intestines, ILIO COLICA COUCA DEXTRA COLICA MEDIA. V. MESENTERICA INFERIOR has, as branches, CO- LICA SINISTRA HJKMORRHOIDALIS INTERNA. VI. CAPSULARES These, though called here primary branches, are very irregular, coming generally from the Renal, and even sometimes from the Phrenic. \ 7 II. RENALIS DEXTRA ET RENALIS SINISTRA. to the Kidneys. VIII. SPERMATIC A, to the testicles in man to the ova* ria in the female. IX. IRREGULAR BRANCHES, to the Ureters, &c* X. LUMBALES Five on each side. XI. ILIAC^E COMMUNES, divided into the ILIAC* EXTERNJE, and ILIACJE LNTERNJE. XII. SACRA MEDIA. The table of the arteries of the pelvis will be given after the description of the dissection of the parts in the pelvis. The nerves of the abdomen, though difficult to dissect, *rc eas^y arranged, for they some principally from Uvv ?eat sources, the par vagum and the sympathetic. But, as it is not possible to form an accurate idea of them, without, at the same time, having those of the thorax dissected, I shall defer the description of the manner of dissecting them, until we come to the examination of the thorax. MANNER OF EXAMINING THE MINUTE STRUCTURE OF THE VISCERA, The minute structure of the viscera ought to he more at- tended to than it generally is in the dissecting room ; but a*? I cannot enter fully into the description of it here, I shall only point out the manner of proceeding. After the liver, stomach, duodenum, spleen, and pancreas have been removed, in connection with each other, from the body, certain parts will be seen more distinctly than when they were in situ. The examination of them will be facilita- ted if w r e distend the stomach with air, for then the entry of the oesophagus into the cardiac orifice of the stomach, the great curvature, the lesser curvature, and the attachment of the spleen to the stomach, through the medium of the vasa brevia and membranes, will be easily understood. The dis- sector will, of course, a_gain examine the several vessels and ducts of the liver and pancreas. The greater part of the stomach is covered by the perito- neum, which is called its peritoneal coat. By stripping off a portion of this, the muscular coat will be seen, the princi- pal fibres of which may be traced from oesophagus. Before examining the internal coat, the stomach should be separa* ted from the other viscera, by cutting through the duode- num, immediately below the pylorus. It is then to be open- ed, or inverted. The internal, villaus, or mucous coat varies in its appear* ance in the several parts of the stomach. IS ear the esoph- agus, it resembles fine cuticle, which, in some cases, may be seen to terminate in a distinct line. In the great curva- ture, it has more the appearance of a secreting coat ; and in some animal?, there is a distinct glandular apparatus here. Towards the pyk-.rji?, the mucous coat assumes the charac- ter of the inner membrane of the intestines. We may now sec the impropriety of calling the structure at the pylorus, a valve, ibr it is distinctly a sphincter muscle, which, according to the ancients, was as a porter, that would not let any indigeetibie matter pass ; from this idea of its use, they gave it the name of pylorus. The student may form a more correct idea of the structure and functions of the different parts of the stomach, by exiu 60 mining those of certain animals, particularly of the horse, or ass, for the cuticular lining on the upper part ; of other do- mestic animals, for a glandular appearance near the pylorus ; tind of the sheep, or ox, as examples of the complicated struc- ture of the stomach of the ruminating animal, which forms a contrast with the stomach of those of the carnivorous kind, as the dog, cat, lion, &c. The stomach of birds is also worthy of examination, as there is not only much difference in its structure from that of an animal of the class of the mammalia, but there is also much variety in the stomachs of the different classes of birds, as of those which live upon grain, and those which are carnivorous. The opening by which the ducts enter into the duodenum, is to be particularly attended to ; when the gut is laid open, or inverted, it may be seen ; but as the duct opens obliquely into the intestine, we shall be generally obliged to pass a probe from the ductus communis choledochus into the gut, to mark the point at which it enters. A few muscular fibres resembling those of the ureters in the bladder, may be dis- covered in connection with the opening. The whole of the intestinum tenue is of the same struc- ture, having a peritoneal, muscular, and villous coat ; but as the jejunum is a larger and thicker gut than the ileon, the different coats will be more distinctly seen in it. If we tear off a portion of the peritoneal coat, in the direction of the length of the gut, we shall see the longitudinal muscular fibres ; if we take it off in the circle, the circular fibres will be shown. The muscular coats of the stomach and intes- tines will be more distinctly seen after the part has been plunged once or twice into boiling water. The valvulre con- niventes, or folds of the mucous or villous coat, will be seen by inverting a portion of the intestine, and putting it into water; if we distend the inverted gut with air, and then squeeze it, we shall show the cellular coats. The minute structure of the intestines is more distinctly shown by injecting part of them with size and vermilion ; to do this nicely we should cut off a portion of intestine, with its mesentery, and, after tying the txvo ends of the gut, put a pipe into that vessel which appears to be the trunk of the branches that are passing to the intestine. Upon the injected gut, some small transparent vessels may be seen, running in a longitudinal direction ; these are the lacteals ; and by opening one with a lancet, we may distend it with air, or mercury, which perhaps will pass into the glands of the mesentery, and then into the secondary- vessels which pass to the thoracic duct. When the injected gut is opened, the villous nature of the internal membrane 61 will be more evident ; perhaps some white points may i>. seen upon the surface ; they are the mouths of the lacteal^ full of chyle ; but this appearance will only be found when the process of absorption lias been going on immediately previous to death. The best illustration of the lacteal sys- tem is made, by giving an animal some meal and milk about an hour previous to killing it, and by putting a ligature round a part of the intestines, or by tying the thoracic duct imme- diately after death. The lacteals will be then distinct!} seen, filled with the white matter which is called chyle"; they are much more numerous on the jejunum, than on the ileon. The colon is next to be examined : there can be no diffi- culty in distinguishing this from any of the other intestines ; for we have not only the great omentmn attached to it, but also little projections of peritoneum, called appendices epi- ploicae, or ornentula ; but the longitudinal and circular bands of muscular fibres, are the most distinguishing mark;-. The circular bands are very numerous, but there are only three longitudinal ones. On examining the gut more mi* iiutely, we shall find that there are very few lacteals upon it, but plenty of absorbents ; and on the inner surface, tha* there are few valvulaa conniventes. The parts at the union between the ileon and colon ar*> complicated; when the gut is distended we see them mon- distinctly ; the whole is called capitt co/i, upon which we par- ticularize, the ceecum, which is the name given to that gut which, in horses, is nearly a yard long, but in the human body, it is only about two inches in length, and is not ob- servable except when distended with air ; tlie processus ver- miformis will be easily discovered, from its resemblance to an earth worm. The valve between the colon and ileon cannot be well understood except when the gut is dried ; but even in the fresh state, on opening the caecum in water, the valve may be seen to be formed by the projection of part of fhr muscular and internal coat of the ileon into the colon, .so a s to present an appearance like the flood-gates of a canal-. The peculiarities of the rectum will be observed in tin- dissection of the parts contained within the pelvis ; at pre sent, I shall only remark, that there are in the colon, and particularly in the rectum, mucous folicles, which have been called glandulee solitariae, to distinguish them from folicles which are found in sets in the small intestines, which have been there called the glandulee aggregate : these openings are more distinctly seen in the rectum of the hone o? ass, than in the human body, F 62 The most "important parts of the liver have already In- seen ; but when it is completely separated from the other viscera, some points may be more easily understood. If the liver has been taken from a young body, then the substance of the round ligament will not be firm, nor completely closed in the centre, but so open, that a probe may be pushed into it; this is in consequence of the umbilical vein which degen- erates into the round ligament, not having yet become so firm as it is found in the adult. If we trace the round or umbilical ligament, we shall find it become connected witli the vena ports?, and then pass to the upper and back part of the liver; but it does not retain the same name through its whole course ; for as, in the foetus, the vessel which passed from the vena portse, though really a continuation of the umbilical vein, was called the ductus venosus, so is the ligamentous matter, in the adult, above the transverse fissure, called the remains of the ductas venosus ; and even the portions of the great fissure receive names corresponding to the terms used in describing the two portions of the umbilical vein which lie in them. There are only two fissures in the liver which should be named : the Umbilical, which divides the right from the left lobe, and the Transverse, in which the great branches of the vena portes lodge. But anatomists have chosen to call the sulcus, in which the gall bladder lies ; the fissure of the gall bladder ; and the depression on the back part of the liver, for the passage of the great vein, has been called the fissure of the vena cava, though it is not unusual for the eava to pass through the substance of the liver ; even the notch corresponding to the convexity of the vertebra?, is sometimes called a fissure. Besides these fissures which are generally described, there are frequently irregular de- pressions, as if the lobes had been cut with a knife. There are generally five lobes of the liver described, but the two great lobes and the lobulus Spigelii are the only important ones ; for, the lobulus quadratus, or anony- mous, is only that portion of the liver which is between the gall bladder and the umbilical fissure, while lobulus, or processus caudatus, is the name given to that part of the right lobe which projects to the lobulus Spigelii. On the surface of the liver there are a great many lym- phatics, the branches of which can be injected from the trunks, as the valves may be broken down by the weight of the quicksilver. The greater number of the trunks pass to- wards the porta, so that they, also, as well as the principal vessels and nerves of the liver, are contained within the capsule of Glissou, 63 The substance of the liver was called by the ancients, pa- renchyma ; a name implying little more than a confused mass ; and if we make a section of the liver, though we shall see a great number of subdivisions formed by the mem- brane which supports the various sets of vessels, still they are so bound together, that it is very difficult to ascertain the real structure of the gland. The small round bodies, of which the substance is principally composed, have been called acini, and have been supposed to be the terminations of the very minute branches of the vena portse, which are called perdcilli. The biliary ducts, which have been descri- bed as conveying the secretion from the acini, are, at their commencement, called pori biliarii. The examination of the structure of the spleen will be still less satisfactory, for we cannot even discover a duct in it. When the substance is minutely injected, it appears to be made up almost entirely of vessels, the extremities of which appear to communicate with cells, which are con- nected by cellular membrane that has a particular stellated appearance when a section is made. The use of this part will probably remain always a problem ; but when we look to the immense size of the vein passing from the spleen to the vena porta?, we must suspect it to be in some way subservient to the liver. The pancreas has much resemblance, in its structure, to the parotid; and if we inject its duct, we shall find it dis- tributed in the substance of the gland, in the same manner as the ducts are arranged in the salivary glands about the jaw. The structure of the kidney is more easily understood than that of any other viscus. The parts may be seen in the uninjected kidney, but much more distinctly in one which has been minutely injected. Before we can understand the structure of the adult kid- ney, it is necessary to know, that in the foetal state, it is composed of a number of lobes, which give it, at that age, y, lobulated form ; but to see the several lobes in the adult kidney, we must make a section of it. Each lobe may be considered to be almost independent of the others ; for a separate branch of the renal artery passes to each, and has so little communication with those of the other lobes, that we may inject each of them with a different coloured fluid. The cortical part of the kidney appears to be that in which the secretion of urine is effected. It is highly vascu- lar, and when minutely injected, small round bodies, which are called corpora globosa, or crypto, are seen in it ; these have r by some anatomists, been described as small glands, 64 by others, as the termination of the convoluted artery- Prom these bodies we may discover small lines passing to? wards each of the white papillae in the centre : these lines- are said to be the tubuli uriniferi, terminating in the ducts that are called the ducti Bellini, and which carry the urine that is secreted in the cortical part to the papillae. Upon each papilla a depression may be seen, ana if we squeeze the part of the kidney corresponding to it, a little urine will drop from it. The pelvis, is the name given to the membrane forming the upper part of the duct, or ureter ; the portions of thii which pass up on each papilla, are called either calices or inilindibula, according to the manner in which they aro. examined; thus, if we look to them as running upwards, pad! part will resemble the calyx of a flower, but if we fake them in another view, they will appear as little fun-: uels. The structure of the kidney differs much in certain classes of animals, from that of the human body. In the kidney of the sheep, there is a very close resemblance to that of man ; bat in the lion, dog, cat, &c. the kidney is never tabulated, but has only one papilla, whence it is called a single kid- ney. In the ox it continues tabulated through the whole life of the animal : but the best examples of the tabulated kid- ney, are those of animals which occasionally inhabit tha water, as the bear, seal, &c. The capsula renalis, or, as it has been called by the an- cients, glandula atrabilaris, is of very curious structure, re- sembling a piece of fat : in the foetus, it is large, in propor- tion to the kidney ; but in old age, it is hardly possible to, discover it; the only thing observable in it, is a cavity, iu which there is occasionally a thick blackish fluid. I trust that this short sketch of the manner of investigat- ing the minute structure of the viscera, will be considered as only an endeavour to induce the student to prosecute this subject, which, though difficult, is highly interesting and important. SOME OBSERVATIONS ON THE MANNER OF EXAMINING A BODY TO DISCOVER THE SEAT OF 'DISEASE.. When called upon to make a private examination of the state of the abdomen of a person who has died inconse- quence of visceral disease, we should endeavour, in open- ing the body, to disfigure it as little as possible, The best- 65 manner of proceeding is, to cut through the skin only, in the line of the linea alba, beginning a little above the middle of the sternum, down to the pubes. The skin may be quickly dissected from the muscles, and pulled over to- wards each side : the muscles may then be cut in any direc- tion. If the body is not very fat, this longitudinal cut in the skin will give us sufficient room for our examination ; but we may be obliged to make a transverse incision below the umbilicus. When the dissection is finished, and the skin is sewed up, the incision should be concealed by strips of strongly adhesive plaster. The morbid anatomy of the viscera is a subject so exten- sive, that it is not possible for me to enter into it fully here. All that the limits of this work will permit, is, to endeavour to point out a few of the circumstances which are liable to lead those who are not conversant with anatomy, to make erroneous statements of the appearances which they see in making the examination of a body. It is not unusual to see a minute description given of : a very curious displacement of the viscera ;" but the posi- tion of the viscera in the dead body depends on such a varie- ty of circumstances, that we ought not to attach importance to any trifling change from that which is considered natural. The bmentum is frequently described as extra sedem : but, if I were to take the description of the omentum from the common appearance which it has in bodies after they have been moved, I should, have great difficulty in saying what its natural situation really is. I have observed, that if there has been any inflammation in any one of the viscera, at any period, that the omentum is found attached to it : thus, the most common appearance of disease in the abdomen of the female, is adhesion of the omentum to the uterus. It is a very common mistake to describe the loaded state of the vessels as an appearance denoting previous inflamma- tion : the state of the true inflamed intestine is so distinct, that it can hardly be forgotten after it has been once sees, In the first stage, there are numerous small vessels segn upon the gut, Tike those on the eye in ophthalmia, with a suffusion around them ; in the second stage, there is matter, or lymph, effused ; and in the more advanced state, adhe- sions are formed between the surfaces of the intestines. But there are many different lands of peritonitis. In that which is called idiopathic, the peritoneum will be found coated with lymph ; but after inflammation in consequence of strangulated hernia, the substance of the intestine will appear more affect- ed than the proper peritoneum. I cannot enter farther on 66 this important subject; but shall refer to a very early work, by Mr. Bell, in which much interesting matter on the mor- bid anatomy of all the viscera will be found. We must not fall into the mistake of supposing-, that the air which rushes out when the abdomen is opened, has been formed during- the life of the patient ; for though there may be cases of true tympanitis, still the most probable cause of the formation of this air, is the change produced after death by putrefaction. In some cases of gangrene of the intes- tines, air may have escaped .into the general cavity immedi- ately before death. The great distention of the stomach and intestines, is also commonly produced by the change which takes place in their contents after death; though there is always more or less air within the intestines during life. From the variety of appearances of inflammation, from the black spots, and from the ulceration and corrosion, which, in the course of my dissections, I have seen in the stomachs of those who have died without any marked symp^ toms of affection of that viscus, and from the close resem- blance which many of these have had to the stomachs of those persons who have swallowed poison, and from the similarity of the appearances produced by gastritis, and other diseases, to those caused by poison, I have come to the conviction, that the appearance of the stomach or int^s- . tines alone, in a question of poison, is not to be depended on* In the last book that has been written on poisons, (that of Or- filia,) the list of appearances which is given, as to be expect- ed, where poison has been taken, corresponds exactly with those which I have found in stomachs where I was certain no deleterious matter had been taken. I am happy to think, that this degree of uncertainty will prevent the anatomist from being called On to decide a question which may involve the life of a fellow creature. In examining the abdomen of children w r ho have died in consequence of irritation in the bowels, we shall frequently find one portion of the gut invaginated in the other. This is introsusceptio ; but in the child it is seldom the cause of death, while in the adult it is generally attended with such inflammation as to produce strangulation and death. If a . patient has died with symptoms of hernia, and no external tumour be discovered, we may expect to find an introsus- ceptio, or a portion of the intestine strangulated, by a noose formed of cojidensed omentum, or mesentery ; in these ca- ses, the portion of gut above the point of strangulation will be red, thickened, and distended, while the portion *-vi'j be nale and emptv. 67 If a patient has long suffered from chronic inflammation of the abdomen, we may expect to find the intestines com- pletely glued together : this is a common appearance in the abdomen of those who have been repeatedly tapped. In the scrophulous child we shall probably find the mesenteric glands enlarged and cheesy ; in such a case, the lacteals will be often found filled with scrophulous matter. In the greater number of those who die of fever, the mtestines appear gorged with blood not inflamed ; but on opening the lower part of the small mtestines, we shall ge- nerally discover small ulcers, with thickened edges : this appearance is almost always found in the great intestines of those who have died of dysentery. I may here remark, that a small pouch occasionally projects from the side of the ileon ; but this is considered only a lusus, it is called diver- ticulum ilii. The most common appearance of disease in the liver, is the tubercle ; and this occasionally suppurates. When we look to the proximity of the colon to the liver, and know, that in the previous inflammation they generally adhere, we cannot be surprised, that an abscess of the liver should occasionally communicate with the colon, and the matter be discharged by the rectum. If there be gall stones in the gall bladder, or ducts, we must not be surprised to find the coats thickened, for this is a natural consequence of the irritation.. It is hardly possible to say, whether the softening of the spleen is to be considered as a mark of disease, for it is ge- nerally softened, in all old subjects. The peritoneal coat is very frequently thickened, and particularly in those who have suffered from intermittent fever, as the Walcheren. The pancreas is naturally very firm, whence it is not imfrequently described, by those not familiar with anatomy, as scirrhous ; but I suspect, that, like the other salivary glands, it is very seldom diseased. A softening and tabula- ted form of the kidney, is the first appearance of disease in- this viscus. The kidney may be the seat of primary dis- ease, as of schrophula or stone^but we should always expect to find it more or less altered in structure, when there has been disease or irritation in. the bladder. We should not forget, that there is occasioimlly a yery curious variety in the natural form of the kidney, for, sometimes, the two kidneys are united with each other, sa as to present the form of a crescent, whence this lusus is called the horse shoe kidney. In such cases, I have sometimes found three ureters, but ge- nerally only one. It is not unusual to find two ureters corne from one of the kidneys, whichj in other respects, is of the: common form, 68 DISSECTION OF THE PARTS IN THE PERINEUM. AFTER the student has finished the dissection of the mus- cles and of the viscera of the abdomen, he should, in union with his companion, dissect the parts in the perineum ; but if the body be that of a female, he had better proceed to the dissection of the muscles of the thigh. It is almost need- less to remark, that before the muscles of the perineum can be shown, that the students who are dissecting the upper half, and to whom all the muscle's of the back belong, must either permit the body to be cut through at the loins, or to be put into a certain position. Although some of the mus- cles of the back must be cut in dividing the body, still it will be to the advantage of all parties that the division should be made, for the four dissectors must now necessarily in- terfere very much with each Qther. When we consider the operations which we may be called upon to perform on the parts in the perineum, we shall have a just notion of the necessity of the study of the anatomy of this part, to the surgeon who proposes to be an operator. But when it is known, that a common abscess in the peri- neum has not unfrequently been the cause of death, in con- sequence of the peculiar formation of these parts, it will be allowed, that the study of the minute anatomy of the peri- neum, should not be confined to the operating surgeon only. No one will assert that he can safely manage even the slight- est obstruction in the urethra, unless he knows every turn of the passage : and if he cannot be confident in his treatment of a most common case, how can he possibly understand the proper and safe treatment of those complicated fistulse which are now so frequent, and which require such nice opera- tions ? It might be thought that such observations were quite unnecessary, were it not a common opinion among students, that even the operation of lithotomy may be performed, by one who is not conversant with the anatomy of the parts, if lie makes use of instruments which are nicely adapted t i other- 69 Though much has been written on the perineum, and though many valuable observations have been made on par- ticular parts, still the anatomy of it is so complicated, that I have found very few students who were capable of making themselves masters of the many points of interest, unless they went through a regular series of dissections. I shall, therefore, endeavour to describe such a course of dissections of the perineum, as will enable the student to comprehend the simple anatomy, and also the manner of examining the parts, so as to discover the causes of difficulty in the seve- ral operations. In such a complicated structure as the outlet of the pelvis, it will be absolutely necessary to dissect the parts many times : I shall, therefore, in pointing out what I conceive to be the best plan of proceeding, endeavour to describe it, that the student may make the most of each body which he dissects. I shall first show the method of performing the dissection so as to enable the student to acquire a general idea of the muscles, and of those parts which are connected with, tho passage of the semen, the urine, and the fceces. POSITION OF THE BODY. Tie the hands and feet so as to put the body in the same position in which a patient is placed for the operation of lith- otomy ; then put a block under the sacrum introduce a sound into the bladder tie the glans penis to the upper part of the sound, and then fix it in the centre, by tying it to both knees. Before commencing the dissection, the rectum should be desired of its contents, by throwing in water forcibly with a syringo ; a little baked hair is then to be pushed into the rectum, and a round cork, with a string tttttichud to it, should bo passed just within the sphincter : this will be found useful in bringing the sphincter forwards. Place a pelvis in the same position as the body, and com- pare the ramus of the pubes and ischium, and the tuberosity of the ischium, with the same parts in the subject ; then make the first incision along the ramus of the pubes and ischium, down to tho tuberosity of the ischium. Make a second through the skin only, along the Raphe, in the mid- dle of the pern's, to within of an inch of the anus ; and then a third, from the one on the tuberosity of the ischium, to the termination of the cut on the Raphe. Make stilif another incision through the skin round the anus, beginning te union of the cross and. longitudinal incisions; and. 70 lastly, feal for the os coccygis, and make a cut from it to the circular one around the anus. (a) These incisions will enable us to expose the principal mus- i-les. The cut along- the ramus of the pubes and ischium, vill show the course of the erector penis : the cross cut, that of the transversalis ; the incision along the Raphe will show the union of the two ejaculators ; and the circular cut will be in the line of the fibres of the sphincter ani. It is better to make these incisions on both sides ; for I have al- ways found that the student got a very imperfect idea of the anatomy of the perineum, from the examination of one side only. The dissection is to be begun by cutting on the line of the ramus of the pubes and ischium, so as to expose the fibres of the erector, which will be found to form a tendinous ex- pansion that spreads upon the crus of the penis. But we must be particularly careful in dissecting the origin of this muscle, for the transversalis is connected with it. The same dissection should be made on the other side, and then there will be a distinct view of the crura of the penis, and the at- tachment of the erectors. The next step will be, to dissect, in the line of the cross cut, as far as to the union with that in the line of the Raphe, with the intention of laying bare the fibres of the transver- salis. But the student is very liable to be foiled in his first attempt to dissect this muscle, because its fibres are not only frequently very indistinct, but its place is often supplied l>y a set of fibres from the levatur ani. Sometimes, indeed, we may discover two transversales ; while in other bodies there is no proper transversalis, but a set of fibres which, though they may have the same origin, take a direction ob- liquely upwards. This slip of fibres has been called the transversalis alter. The transversalis is considered regular. figure ; the two obtuse angles of are inward from the tuberosities of the iechia : consequently, it has an anterior acute angle at the arch of the pubis : the posterior acute angle being in the situation of the apex of the sacrum, from which the os coccygis is seen stand- ing forward, this bone having its motion within the apace of the outlet. By reason of the more depending situation of the tuberosities of the ischia, the boundarie^ of the outlet are not on a plain ; but are to be considered collectively as forming an obtuse angle at an imaginary line ^tending- from one tubcrosity of the ischium to the other. 71 when it is inserted with the other muscles into the condens- ed cellular membrane on the lower part of the bulb. The ejaculator seminis may now be shown by dissecting carefully from the cut in the Raphe, towards the erector pe- rn's and cms of each side. After the fibres of this muscle are exposed, the loose skin should be taken off from the penis> so that a more distinct view of the parts may be given. We may now proceed with the dissection of the lower part, by cutting in the line of the incision which has been made round the verge of the anus, so as to expose the fibres of the sphincter. In doing this, the dissector will discover, that the most superficial set of fibres is attached to the skin in the line of the Raphe, but that the greater mass of the muscle is inserted into that point at which the two transver- sales and ejaculators unite ; indeed, this point is often called the " common centre of union." When the dissection of the sphincter is continued up for about an inch upon the rectum, some of the fibres of the levatur ani will be seen ; but, to expose the whole of this muscle, it will be necessary to remove a large quantity of fat and cellular membrane from the side of the rectum. This may be done very boldly, if we keep below the level of the trans versalis, for we may, without fear, set our knife on the edge of the tuber ischii, and carry it full of an inch in- wards and downwards, without the risk of cutting any fi- bres, except some of the gluteus maximus. The object of this first dissection being only to acquire a general knowledge of the relative situation of the principal parts, we ought not at present to attend to the vessels, but proceed to remove the superficial muscles. It will not be necessary to remove the erectors, for the erura penis are sufficiently distinct while they are attached to them ; but the fibres of the ejaculator and of the transversa- lis, are to be carefully raised, so as to expose the spongy body and its bulb. After removing the fibres of the ejacula- tor, which arise from between the erector and bulb, the fas/- cia, or ligament, which is called triangular, will be seen ; or by pushing in the finger, the ligament will be felt. After studying the appearance of the parts now presen- ted, a dissection of the pelvis should be made, so as to show the penis, bladder, &c. in their mutual relation to each other. The penis and bladder should be left attached to the right limb, that there may be a view of that side which is cut in the operation of lithotomy. The first step, in making the section, is to cut the left crus of the corpus cavernosum from the ramua of the pubes and ischium, and through tl;e 72 skin of the pubes and muscles of the abdomen; taking care to avokl the spermatic cord and testicle. The body is then to be untied and laid upon its back, the staff is to be taken out of the bladder, and the hair from the rectum. The hand is to be introduced into the pelvis (it is presumed that the muscles of the abdomen are already dissected ; and all the viscera, except the rectum and bladder removed), and the rectum and bladder are to be pulled over towards the right side ; taking care that the peritoneum be not torn from them* nor the ureter injured. The division of the bones are now to be made, by cutting with the saw, not exactly through the symphysis, but father to the left of it ; but in doing this, we must take care that we do not cut the origin of the gracilis muscle, on the inside of the thigh. The bone having been sawed through, and the viscera of the pelvis held aside, and the fibres of the levator arii being carefully cut, the knife (without regarding the pyriformis, great nerve, &c.) is to be carried through the parts, up to the notch of the ilium ; and then the thighs being forcibly pulled asunder, the left leg will be separated from the trunk, at its union with the sacrum. Tire muscles on the back part are then to be cut, and the left limb removed. In making this section, some of the arteries and nerves, with certain muscles of the left side, will be necessarily destroyed ; but they may be preserved if we make the division more in the middle of the pelvis ; to do this, we must pull the viscera quite over to the right side, so that we may saw through the middle of the sacrum and the symphysis of the pubes ; but in doing it, we must carefully avoid the urethra. By pro- ceeding in this manner, the muscles of the hip will be saved, but still the deep muscles of the back must be cut through by a cross incision ; however, these muscles are of little im- portance, compared to the parts seen in the lateral view of the pelvis : indeed the body should be divided immediately above the sacrum, before the perpendicular section is made. This last method may be sufficient to give a general idea of the bladder, rectum, and urethra ; but to form an accurate notion of the relation of these viscera to each other, we must make the section according to the manner first de- scribed. The view which is now given, will seem somewhat confu- sed to a dissector, in his first essay; for he will not, ae yet, be able to distinguish the bladder or rectum : but to make them distinct, it is only necessary to distend them. By in- troducing a, blow-pipe into the urethra, the bladder may be blown up ; but if the staff has been passed into the urethra, 73 *h' bladder may be distended by blowing into one of the uiv t ers. A small quantity of hair is again to he put into the rec- turn. The form and situation of the bladder will now 1 < distinct ; but as the surface will still he obscured by the pe- ritoneum which covers a great part of it, it may be useful, even in a first dissection, to pay some attention to the fold* of this membrane. The peritoneum will be seen passing from the muscles of the abdomen to the fundus of the bladder, and from that, continued down upon the back and lateral parts. It then ri- ses on the front of the rectum, so as to form, a bag. or pouch. between the bladder and rectum : the lateral boundaries of which are sometimes called the posterior ligaments of the bladder. If the lower part of the muscles of the abdomen be still entire, we may see the remains of the umbilical arteries running up along the- lateral parts of .the bladder to the um- bilicus, and, between them, the urachus passing from the fundus. These parts will appear like three thickened lines upon the peritoneum. The peritoneum may now be raised ; it is so loosely con- nected with the bladder at the fundus, that, with the fingers only, w r e may tear it from the muscular coat of the bladder ; but we must remove it more cautiously from the lower pait, or we may destroy the ducts of the testicle, which run on each side of the bladder ; but these ducts are so thick and dense, that, though they may not be seen, they will be easilv felt. If we put small bougies into the ureters, as a guard against wounding them, we may proceed more boldly in re- nioving the peritoneum from the lower part. TLe muscular fibres of the upper part of the bladder will now be seen ; but a great deal of dissection is required to make the parts below, distinct. Part of the rectum is still Covered by the levator ani, whicji ought now to be dissected away, and then a quantity of cellular membrane will be seen between the rectum and bladder. In removing this, the knife, must be used cautiously, until a portion of the vesicu- la seminalis, which lies between the rectum and bladder, is exposed ; it will be known by its dark glistening appearance. If we follow the vesicula forwards, we shall discover the lateral part of the prostrate gland. The bulb should now be made distinct by removing any muscular fibres that may be attached to it ; but we must be very careful in dissecting immediately under it, for the little bodies which are called Cowpers glands, are situated here. These bodies are not very easily shown ; but by taking the bulb between the fiu ger and thumb, we shall readily discover them ; although G 74 they will have rather the feel of condensed cellular mem- brane than of glands. After having made the prostate and bulb distinct, the portion of the urethra which is between them, and which it- called the membranous part, is to be examined. The staff may be felt in it ; but the muscular fibres and ligaments which Furronnd it, give it a very different appearance to what we should have expected to find, from the description there is of it in the greater number of books on anatomy. Such a dissection as has been described, will enable tho young student to understand the principal parts connected with the passage of the semen, of the urine, and of the lv ces ; and will enable him to follow the descriptions which are given in the " Systems of Anatomy." As it will net be possible in this view, to gain more than a general knowledge of the parts which are cut in lithotomy. I shall only remark at present, that, in this operation, after the external muscles are cut through, the knife is introduced into the membranous part of the urethra, and is carried on, so as to cut the lateral part of the prostate ; the level of the incision being sufficiently high to avoid the vesicula semi- nalis. Although the parts may not have been dissected in the manner best adapted for showing the causes which prevent the introduction of the catheter, yet it maf be well to re- move the staff, and again to introduce it. Indoing this, we cannot avoid observing, how liable the instrument is to be caught at the bulb, and the danger there would be of 1orni- ing a false passage, if we force it on. When we open tlie urethra, we shall find that there is, at this point, a natural pouch, which is called the sinus of the urethra. By putting the hand on the bladder, and pushing it towards the rectum, we shall see the attachments which it has to the es pubis, and which are called its anterior ligaments. Be- tween these we may see a number of holes, which form the faby-rinth through which the veins of the penis pass. The rectum should now betaken away, so that we may get a bet- ter view of the vesiculse, vasa defer en tia, and ureters. After these parts have been examined in their relative situation to each other, the bladder and penis should be removed from the piibes. To do this, it is only necessary to separate the right cms of the penis from the bone, and to cut through the ligaments of the bladder, and the vasa deferentia and ure- ters. The bladder, when detached, is again to be distend*- ed, and a straight staff is to be passed into the urethra. The cellular membrane may then be removed more carefully from the tower part of the bladder, so thai the v-eekuta semi*- 75 tales and vasa deferentia shall be still more distinctly seen. To show the lateral lobes of the prostrate, it will be only necessary to remove the cellular membrane, and the large veins that are upon it ; but if we follow the vasa deferentia quite into the prostate, and then separate them from each other, we shall see the little projection of the gland that has been called the middle lobe, and which, in consequence of a mistake made in the description of the morbid anatomy of the prostate, has, of late years, been considered of much more importance than it deserves. We may now take off the muscular fibres, &c. from that portion of the urethra which is between the prostate and the bulb, so as to give it more resemblance to a membranous part, as it is generally described : the staff being still in the urethra, will prevent us from cutting it. The bulb and Cowper's glands should also be made more distinct. Before examining the structure of the cavernous and spongy bodies, they should be distended. One of the crura of the corpus cavornosum is to be tied, and a blow-pipe fixed into the other. Though this body maybe fully distended, the spongy body will still remain flaccid, for there is no direct communication between it and the cavernous body. To dis- r<-u:i it. it will be necessary to make a puncture, sufficient to admit a blow-pipe into its substance. A bougie, or straight staff, being still in the canal, the bladder, prostate and urethra aro to be laid open, by cut- ting them through on the upper part., so as to avoid injuring the points of demonstration, which are all on the lower sur- face. The mucous coat of the bladder will be seen to extend alon.o- the urethra to the glans. In the lower part of the bladder, we may perceive the entry of the ureters, and those little eminences which pass from them towards -the ate; and which have been proved by Mr. Bell to be small muscles for regulating the opening of the ureters. By squeezing the vesiculas, the opening of their ducts, and of the testicle, will be discovered by a brown fluid issuing from an eminence on the anterior part of the prostate, u though called the verumontanum, or caput gallinagi- - only a loose portion of the internal membrane, which ots so as to form a pouch, or sinus, that opens towards the glans. The cavity formed by it has been called sinus igni, or sinus pocularis. By blowing towards th<- biaddev, the membrane will be raised ; but the vesicular will not be distended, as is generally supposed, for their ducts do not open into the sinus, but on each side of the membrane. 76 By squeezing the body of the prostrate, we shall so* white secretion issuing- by a number of ducts on each side of the verumontanum. By a little care we may pass bristles into the ducts ot'Cowper's glands; but they are very small, and. are situated about half an iru v h anterior to the bulb. On the surface of the 'urethra, we shall discover many small openings, that are called lacunae: but the principal one, which is called lacuna magna, is sometimes destroyed in making the section of the urethra, for it is situated on the upper surface, about an inch from the opening of the oflans. The cellular structure of the eavernous body surrounded by the ligamenr.ons membranes, and divided into two por- tions by the septum pectiniforme, will now be understood. No muscular fibres will be seen in the membrane of the ure- thra; but the appearance which has been described as mus- cular, may be easily understood by pulling the membrane in its length, for then the inner membrane will be thrown into folds, having the appearance of fibres. There is, likewise, a set of vessels immediately below the membrane, which, when empty, are very similar in appearance to muscular fibres. I have discovered that tkese vessels form an internal spongy body, which passes d"\vn to the membranous part of the ure- thra, and forms even a small bulb there. This I have par- ticularly described in the tenth volume of theMedico-CIiirur- ffical Transactions. Sir Kverard Home has lately given an account, in the Transactions of the Royal Society, of certain muscular fibres, which he thinks he has discovered in the urethra by the aid of a very powerful microscope; but as he has described them as muscles, the ten'lons of which are of the consistence nf niuf'H'^ we cannot suppose that any spasmodic affection of such muscles will account for the occasional difficulty of in- troducing a bougie into the urethra. I suspect that SirEve- rard has been mistaken in supposing that there are any mus- cular fibres in the urethra, for he does not seem to have been acquainted with my discovery, although it was published two years previous to his paper being read to the Royal Society. Since I described the minute structure of the urethra, in man, in the horse, and in the bull, I have had an opportunity of verifying my opinions, by the dissection of the same part, in the elephant and camel. 1 shall now describe the manner in which the more advan- ced student should make the dissection of the parts int.hr perineum, so as to enable him to understand their pathology, and the operations which it may be necessary to peri' upon them. 77. The arteries of the pelvis are to be injected. The bod} is to be put into the same position as that for the first dissec- tion ; but before this is done, the student may try to intro- duce the catheter into the bladder, taking care to do it lightly, so that he may not break through any of the natural obstructions to the entry of the instrument. The body being put into the proper position, a single cut. is to be made in the line of the Raphe, and the skin only, is to be dissected off to wards each rarnus of the pubes and is- ehium, so as to expose the superficial fascia of the perineum, which is strongly united by firm cellular membrane to the fascia that covers the gracilis and adductor muscles of the thigh, more loosely to the parts about the anus, and still less so to the cellular membrane of the scrotum.* The first circumstance that will naturally excite the attention of the, *iirgical student, is, that if matter should form under this fascia, it will with difficulty gain an exit; but his inte- rest, will be increased, when he recollects the quantity of loose cellular membrane which he found among the muscles of the perineum, in his first dissection : for be will see, that if an abscess under this fascia is not freely opened, the mat- tor may work its way backwards into the cellular membrane, so HS to do irreparable mischief to the parts within. But ?ttf most important view in which this fascia is to be consid- tTfrl, is in the case, where, after rupture of the urethra, the urine is effused into the parts of the perineum. As the urine cannot, in such a case, torce a passage through the fascia, it will be driven up among the loose cellular membrane of tlu penis and scrotum : and here it will very quickly produce gangrene, unless a free incision is made through the fascia. There are very few vessels seen in this stage of the dis- section; but after part of the fascia is cut through, the arte- "i<-s, which are called superficial perinei and transversal!?, will be seen, the first passing up between the ejaculator and the erector, the other running in the line of the trans versn- 3i* muscle. Both of these vessels must be cut, in the opera- tion of lithotomy ; but the bleeding from these small arteries may be of service after such an operation. The superficial fascia may now be raised, and then the muscles which were described in the first dissection, will In seen. After the muscles and arteries have been dissected, tht parts should be studied with reference to the operation ot * The observations which were made on fascice at the .rroin, are also applicable to this fascia. If the subject be tbund very difficult to give them the appearance of a neat small muscle, such as have been described by him, and at the same time to preserve the ligaments of the urethra and of * he prostate, and also the levator prostatae muscle. to show the true cause of the infiltration of urine into thw f-ellular membrane, after the operation of lithotomy. 82 There is not any farther dissection required, to enable us to comprehend the incisions which are made through the in- ternal parts, in the operation of lithotomy. The cut which is made by the best operators, begins about the middle of the membranous part of the urethra, and is continued, in a lateral direction, through the prostate and the sphincter of the blad- der, above the level of the vesicula seminalis. By the view of the parts before us, we may be convinced that in such an incision* no arteries of importance will be cut. The bleed- * It is to be hoped that the prejudice in favor of the gorget, will now give way to the use of the knife, in the operation of lithotomy. The ease and safety with which the operation with the scalpel may be performed, in comparison with that by the gorget, is admirably shown in the illustrations of the ( ireat Operations of Surgery, by Mr. Charles Bell. Mr. Bell has, in his Surgical Observations, published some time ago, given proofs of the success attending his mode of opera- ting ; but they have been lately corroborated, in an extraor- dinary degree, by the history which that excellent surgeon, Martineau, of Norwich, has given, in the Medico Chirurgic- ul Transactions, of more than eighty cases of lithotomy, in which he performed the operation nearly in the same man- ner. As to the question of the high operation, I shall refer to the remarks which I have made upon it in the Journal of Fo- reign Medicine and Surgery, where I hope I have proved, that it is not only a very dangerous, but also a more difficult operation to perform, than the lateral. Although the ob- servations which I have wade in that paper, have by somf been thought more severe than the occasion called for, yet 1 have been mucli gratified and flattered by the manner in which several surgeons of great eminence and learning have spoken of them. But nothing has given me so much plea- sure as to find that my opinions coincide with those of Mr. Martiaeati, who, I have been informed, was pleased to say, that he was sorry he had not read my observations before ho wrote his paper upon lithotomy, as he had taken the same view of the question of the high operation as I had." In the same paper I have dwelt at some length on the ques- t ion of haemorrhage, after the common lateral ^operation. At the time I wrote that paper, I thought that the fears of hae- morrhage, which are entertained by some surgeons, were groundless ; but I have since had an opportunity of examin- ing a body upon which the lateral operation had been per- formed : in the dissection of this body I discovered a good reason for these fears ; for the incision had been begun immr- 83 ing which takes place in an operation that has been well per- ibrmed, will be principally from the large veiiis which may be been surrounding the prostate and neck of the bladder. The next practical question founded directly on the anato- my, is the point through which the puncture of the bladder is to be made from the rectum. After the bladder has been fully distended with water, thf finger should be passed into the rectum, that we may form some idea of the feel of a distended bladder. It is very diffi- cult, even in the healthy state ofthe parts, to distinguish be- tween the prostate^ the vesieulae, and the muscular coat of the bladder; but if there be much cellular membrane inter- posed between the bladder and rectum, and if the coats of the bladder be thickened, as they generally are in tlio**' < ses which require the bladder to be punctured,- I belie vf that it will be found almost impossible to recognize the diil'e- rent parts, so as to mark the boundaries of that triangle whk-h is described as having the peritoneum for its base, the vasa. duttely below the arch of the pub es, and had not been continued further down than the upper part of the transversalis muscle, and even this muscle had not been cut through. Now, it it- easy to understand, that by such an operation, it must be al- most impossible to avoid cutting some important arteries. If this middle operation (as it was called by a young friend of mine) were the one generally performed as the lots opera- tion, it would not then be surprising that some gentlemen should have a desire to change the mode of operating ; for instead of the stone being easily extracted, as it may be, when the operation is performed low in the perineum, it will be pulled by the forceps against thte rami of the pubes, .so that the patient may be dragged ofi'the table before the si on* is extracted. If the stone should be extracted by such an incision, the chances are, that some of the vessels will be cut, and the patient die of haemorrhage : if he escapes this danger, he may still be in jeopardy in consequence of the urine not having a depending opening by which it may easily pass off after the operation. When discussing the operation of lithotomy with some of the young students in the dissecting-room, I have very often, put this question when the body is before them, " What is vour object in performing the operation of lithotomy?" Though this question is considered rather insulting, still if leads them to form a correct notion of one of the great prin- ciples ofthe operation, viz. to cut low in the perineum, that the extraction ofthe stone may not Ire obstructed by thr narrow part of the bony arch. 84 deferentia for its sides, and the prostate for its apex. When I have made this examination in a patient labouring under retention of urine, I confess that my impressions have been, that it must be by chance only that all these parts can b<> avoided in puncturing the bladder : however, it is' some re- lief to know, that in such a case the peritoneum will be re- moved to a greater distance than we would venture to push our instrument in. The peritoneum and the vasa deferentia may be consider- ed as the only parts which it is of much importance to avoid in this operation ; for it is only by those dissectors who have not attended to the practice of surgery, that much import- ance, can be attached to the wounding of the prostate. We should now take the opportunity of practising the ope- ration of sounding. A stone may be put into the bladder, through an opening in the fundus, which is to be closed, and the bladder is to be again filled with water. When the sound is in the bladder, we should try to pass it in several directions, as, round the stone, and over it, and be- low it, so that we may attain some idea of the sensation which is given to the hand by a stone of a particular shape, and in the different parts of the bladder. The finger should be passed into the rectum, and then the stone should be pressed clown towards it, so that we may see the possibility of esti- mating the size of a stone in the living body, by having it be- tween the sound and the finger. The operation of sounding is so important a step, previous to performing the operation of lithotomy, that we should pay particular attention to it. Indeed, by a good surgeon, this is always considered as the most important part of the operation. There is an excellent plate, demonstrative of the various positions which the stone may take in the bladder, given in the illustrations of the Great Operations of Surgery. Before we open the urethra, to examine the several points at which the catheter has been obstructed, we should pas? one down to the sinus of the bulb. While it is held there by an assistant, the urethra is to be opened, and then the point of the instrument will be seen lodged in the sinus. In this view, we shall see that the part of the urethra which is sur- rounded by the circular ligament, has so much resemblance to a stricture, that we can now easily comprehend how it may be mistaken for one in the living body. If in pushing the instrument towards the bladder, we de- press its point, it will again be impeded: if we lay open the Urethra, up to the point of obstruction,* we shall find that it * The great size of the cavity of the urethra, posterior to ir-' (Caused by the fascia of the prostate. By now carrying th catheter forwards, it will fall into the sulcus which is by the side of the verumontanum, and anterior to the sphincter oi the bladder. These are all the obstructions to the passage of the cathe- ter, which will be found in the dead body ; but in the living body, it is a very common occurrence for the surgeon to be foiled in his attempt to introduce the catheter through the part behind the bulb, not so much on account of the me- chanical difficulty, as in consequence of there being very fre- quently a spasmodic action of the muscles which surround this portion, for it is not only the narrowest, but also tlu- most irritable part of the canal. While the view of the section of the pelvis is before us, we should also take into consideration the operations to be per- formed upon the rectum. If the gut be cut-in the operation for fistula in ano, as far up as the linger will reach, we cannot, be'surprised that, after such an operation, a patient should die of haemorrhage; because, by such a cut, not only very large branches of the pudic, but even of the lower mes-enteric artery, may be divided. But, luckily, experience has taught us that it is very seldom necessary to cut more than the sphincter ani, in this operation. We have only to look to the curve which the rectum makes, to avoid falling into the error of supposing, that the difficulty which is offered by the, sacrum to the passing of a bougie, farther than six inches into the rectum, is caused by a stricture in the gut. If we examine the rectum with the finger, we shall find that there is a natural constriction about half an inch above the verge of the anus, here the cuticle appears to terminate, and the mucous coat of the intestine to commence. If we inject the lower mesenteric veins with size, we shall be able to form some idea of the nature of piles : for, in the greater number of bodies, the vein will appear constricted at the point of union between the mucous coat and the cuticle, and distended below it, so as to resemble piles in an early stage of their formation. Immediately above this point, the gut becomes more dilatable : and here it is that fish bones, or the stones of fruit, after having passed easily through the the ligament of the bulb, will explain to us the difficulty often experienced in the attempt to introduce the beak of the gor- get into the groove of a small staff. It is evident, that the dides of the urethra must fall together when cut ; a- diffi- culty which is completely obviated by the large staff which is used by Mr. Bell. H 86 whole intestinal canal, are liable to lodge, and occasionally to cause abscess and fistula. The knowledge of the changes which take place in the urethra and bladder, in consequence of disease, is most im- portant; but, as it would require a volume to detail all the morbid appearances which are found in the urethra and blad- der, I dare not enter upon the subject, farther than to point out one or two circumstances which have been.provedby the dissection of the bodies of those who have died in consequence of stricture. I confine myself to this, the more willingly, be- cause I can conscientiously recommend to the student the perusal of the observations which have been made on the morbid anatomy of the urethra and bladder, in that edition of the work on Stricture, by Mr. Bell, of which I was the editor. Stricture may -take place at any part of the urethra ante- rior to the triangular ligament, but ingerieral it occurs at two points : at an inch and a half from the glans, and at six or seven inches down, i. e. near the bulb. But I have already given sufficient reasons for our being guarded in supposii;f. that an obstruction to the passage of an instrument at the bulb, is produced by a stricture. There are two circumstances, not hitherto much noticed, to which I would particularly direct the student's atten- tion : 1st. That there is n'ot one example in a hundred of stric- ture occurring farther back, than immediately behind the ligament of the bulb. 2d. That the ducts of the prostate, which are naturally very small, are always more or less enlarged in cases vere stricture. It must be evident that certain practical rules are to be de- duced from these facts. 1st, If an instrument is obstructed posterior to the ligament of the bulb, that we may suspect that the cause of the obstruction is not such as will 'be over- come by the same means as a stricture would ; and 2d, Wr can now understand why, in a severe case of stricture, we ought to be content with so dilating the stricture, as to ena- ble the patient to pass his urine freely, and that we should not be too anxious to pass an instrument into the bladder, for; in the attempt, the point may enter into one of the en- larged ducts of the prostate, and consequently produce great irritation, and even lead us to suspect that there is still ano- ther stricture: if, with this idea, we persevere in pushing the instrument on, we shall certainly do irreparable mischief fa* the patient. 87 The urine is very often obstructed in old men, either by general or partial enlargement of the prostate. But as this disease cannot be understood by the appearance of the natu- ral parts, and as it is too important a subject to be treated of in so short a manner as the limits of this book would permit, I shall only remark^ that I think I have proved, by repeated dissections, that the obstruction is seldom, or never, produced by the enlargement of the third lobe, as is generally sup- posed. Some years ago I wrote a paper on this question, which is published in Mr. Bell's Surgical Observations. As in all cases of irritation of the urethra, or bladder, the muscular coat of the latter becomes thickened, we must not be surprised if we should, in the dissection of the body of a person who had died of stricture, discover the bladder in this state, and even having cysts communicating with it ; for when the muscular coat is thickened, it very frequently oc- curs, that a part of the internal coat is protruded between the fibres, and sometimes to such an extent, as to give the ap- pearance of a second bladder. I may also observe, that in the examination of such bodies, we must not express astonish- ment if we discover the ureters to be thickened and inflamed, and the kidneys to be tabulated and full of matter; for it fol- lows, almost invariably, that when the bladder is inflamed, the kidneys and ureters become also affected. TABLE OF THE MUSCLES. The muscles which are seen in the first dissection of the perineum, are ERECTOR PENIS. OR. The tuberosity of the os ischium: running upwards, it embraces the cms of the penis. IN. The sheath of the cms penis. EJACULATOR. OR. The crura penis and body of the pe- nis, and the triangular ligament : the inferior iibres run more transversely, and the superior descend in an oblique di- rection. IN. In the middle of the bulb and spongy body of the ure- thra ; and by the tibre-s of both sides uniting, the bulb is com- pletely enclosed. It is connected behind with the fibres of the sphincter ani and transversalis muscles ; these accordingly co-operate in their action. TRANSVERSALIS PERINEL. OR. The tuberosity of the os isrhium, below the origin of the erector: it runs trans- ely. IN. The ejaculator seminis, and fore part of the sphincter ani. 88 TRANSVERSAL is ALTER PERINEI, OR OBLIQ.UUS. OR. From fhe tuberosity of the ischium, behind the former: it run* more obliquely forwards. IN. The side of the ejaculator semthis. We do not always find both these muscles ; sometimes the one, and not the other. There is occasionally another portion found, which has been deseribed*as a TRANSVERSALIS PROFUNDUS ; but it runs so deep under the others, as to be generally described as a part of the levator ani. SPHINCTER ANI. This muscle consists of fibres, which en- circle the verge of the anus. It may be said to have neither origin, nor insertion into any particular point ; but we may observe, that certain superficial fibres, after encircling the anus, are attached, about an inch above the bulb, to the union of the ejaculator muscles, while a deeper set of fibres are inserted into the union between the transversalis and ejaculator : sometimes a slip runs distinctly to this last muscle, and is called MUSCULUS LATERALIS URETHRA. The fibres posterior to the anus are attached, by a distinct tendon, to the os coccygis. The lower set of the muscular fibres on the rectum, have been by some described as forming an internal sphincter. LEVATOR ANI. OR. 1. Os pubis and os ischium, within the pelvis, as far as the upper edge of the fbramen thyroi- deum ; 2. from the thin tendinous membrane that covers the obturator interims and coccygeus muscles ; 3. from the spi- nous process of the os ischium. Its fibres run down con- verging. IN. The sphincter ani, and verge of the anus, and anterior part of the two last bones of the coccyx. It surrounds the extremity of the rectum, neck of the bladder, prostate gland, and part of the vesicula? seminales. USE. To sustain the contents of the pelvis, and to help in ejecting the semen and contents of the rectum; to restrain the protrusion of the anus in evacuation of the faBces. I shall describe the coccygeus here, though it cannot pro- perly be considered a muscle of the perineum: COCCYGEUS. OR. Tendinous and fleshy, from the spinous process of the os ischium, and the inside of the posterior sacro- ischiatic ligament. From this narrow beginning, it gradu- ally increases, to form a thin fleshy belly, interspersed with tendinous fibres. IN. Into the extremity of the os sacrum, and nearly the whole length of the os coccygis. USE. To move the os coccygis forwards v 89 In dissecting the parts exposed by the section of the pelvic, we may observe certain small muscles, the connections of which are so difficult to show, that there are hardly two au- thorities who describe them in the same manner,. so that they have been frequently a subject of dispute : they are, the COMPRESSOR PRGSTATJE ami tile COMPRESSOR, Or LEVATOR URETHRA. According to the best authorities, the compres- sor prosta.tse arises, in loose fibres,' from between the symphy- sis pubis arid the membrana obturans ; it then runs back- wards, to the prostate gland and vesiculse seminales. The compressor, A PR>PAIA, Which ClltClV- i lie cavernous body, and into the .i; pi-:iMs, which passe* towards the glails. The deeper arteries v\ Inch arc set-.n in the lateral section. will be described with those of the pelvis. The veins are here, as in the other parts, named accord- ing to the arteries which they accompany. The ve. ' inth formed by those coming from the cavernous body, and the plexus of veins which surround the prostate gland, should be more particularly attended to, than the ^A' ones. 90 The nerves which are seen in the first dissection of the perineum, are branches of the pudic. The principal branch is found either above or below the transversalis muscle : several smaller twigs are sent to the muscles, while the trunk of the nerve passes, along with the pudic artery, into the penis. The parts within the pelvis are supplied with nerves prin- cipally from the hypogastric plexus, which will be described with the nerves of the abdomen. DISSECTION THE TESTICLE. IT is more important to have an accurate idea of the for- mation of the coats of the testicle, than of the structure of the gland ; because, without this, we cannot form a correct opinion upon the varieties of hydrocele and hernia. But as we cannot attain it, without examining the testicle in its de- scent in the foetus, I shall, before describing its structure in the adult, point out some of the changes which take place in its coverings, during the existence of the foetus. If we examine a foetus of six months old, we shall disco- ver the testicle lying under the kidney, on the fore part of the psoee muscles, and covered by the peritoneum, which adheres to it, in the same manner as to the viscera of the ab- domen : we may also observe a ligamentous, or cellular cord, which stretches up from the inside of the abdominal ring to the body of the testicle, this is the GUBERNACULUM TESTJS. In a foetus at the eighth month, we shall probably find the testicle lying in the inguinal canal, and a small portion of peritoneum projecting before it, towards the scrotum. But if we examine a child at the period of birth, or a short time after it, the testicle will be found in the scrotum* and covered by two portions of peritoneum ; the most superficial, is the same as that which, iu the foetus of eight months, projected 91 into the inguinal canal, the other, which adheres to the body of the gland, is the same which covered the tgs&eiu while it lay in the loin. If, at this period, a probe be"push- ed upwards between the two portions of the peritoneum, it will pass into the abdomen ; but in the adult, though the two portions of the peritoneum are still distinct from each other, we shall not be able to pass a probe farther than the upper part of the scrotum ; because the communication with the abdomen is now closed by the adhesion of the peritoneal surfaces. I shall now suppose that we are to make a dissection of the testicle, scrotum, &c. in an adult. We are told, that on cutting through the skin, we shall see the muscle which is called the DARTOS : but although there is an evident power of contraction in the skin of the scrotum, we shall seldom be able to discover muscular fibres under it, but, instead of them, a quantity of loose cellular membrane, which can easily be inflated with air. In blowing this up, a sort of natural septum will be seen between the two sides of the scrotum. This cellular structure is very often distended in general anas area, or in emphysema. The distention of it in either of these cases, is comparatively harmless : but if it be filled with urine, after the bursting of the urethra, it will be attended with more danger ; for if the urine be allowed to lodge, the membrane will become quickly gangrenous,. The scrotum may now be dissected off, so as to show the testicle and its cord. The cord is composed of a number of different vessels and nerves, which are surrounded by a tissue of cel- lular membrane, called the TUNICA VAGINALIS COMMUNIS. Upon the upper surface of this, are fche scattered fibres of the cremaster muscle. We may now take the testicle in our hand ; and if there has been no inflammation of the parts during life, we shall feel the body of the gland slipping about, as if it were con- tained within a sac. By dissecting on the fore part, we may open this sac, so as to show the gland lying within it. It is called the TUNICA VAGINALIS ; being the same portion of peritoneum which we saw projecting into the scrotum before the descent of the testicle. But we shall now find, that though this is called a sac, that it does not contain the whole testicle, as in a sheath, but only the two anterior thirds of the body of the gland, which will be seen covered with the dense white glistening coat, which was formed by the adhe- sion of the peritoneum to it, while it was within the abdo- men. This latter coat has, by the best authorities, been named "tunica albuginea," but by others, "tunica vaginali* reflexa;" the name " albuginea" being- given by them to s 92 dense fibrous matter which is under this coat, and immedi- ately invests the testicle. There is, however, some difficult} in determining which is the most proper name : for even Mailer is not very distinct in his definition of the two coats : but I am inclined to call the peritoneal covering, the TUNICA ALBUGINEA, because the name seems to have been origi- nally a surgical term, used in describing the white dense appearance of the peritoneal coat of the testicle, when the s;u- of a hydrocele was opened. It is observed in Warner's Treatise on the Testicle, that the "tunic a albuginea, so named from its complexion, is a compact, firm, white, strong, and smoothly polished membrane., having a tendinous ap- pearance;" and Pott, in speaking of hydrocele, says, "this fluid, in a natural and small quantity, serves to keep the tu- nica albuginea moist, an 1 to prevent a cohession between it an:l the tunica vaginalis*" The term Cw tunica vsginalis reflexa" is very objectionable, beccuise, as it is not used by any surgical writers in the de- scription of hydrocele or of congenital hernia, it is very liable to lead a student into great difficulties ; and, moreover, it is givon to a part which covered the testicle, while it was yet within the abdomen, and, consequently, before that which L^ called -'tunica vaginalis" was formed. If we wish to dis- tinguish the two portions of the peritoneum which are within the scrotum, wo may call that one in contact with the body oT the testicle, the Peritoneal Covering, and the other. the Reflected Peritoneal Coat of the testicle. as we distin- guish the part of the peritoneum which covers the intestines, from that which lines the abdominal muscles. By maceration, we may show the -fibrous: texture whic under the peritoneal covering ; but by this process of dissec- tion, we shall destroy all resemblance to a coat which we would call " rtlbuginca." Before dissecting farther, we should consider the surgical anatomy of these coats. We can now understand how, in a common hydrocele of the adult, the body of the testicle will be on the back part, and the water which is confined between the tunica vaginalis and albuginea, will form the anterior part of the tumour. We can also comprehend how, in a child, where the connection with the abdomen is not closed, that there may be a hydrocele which may be emp- tied by pressure and change of position, but which will a win rdurn when the child is put on its legs. It is also evident, that as loner as this communication remains open, that a portion of the intestine may come down into the ?r between the tunica vaginalis and albuginea, so as to forta the species of inguinal hernia which is called congenital.. 93 In dissecting the cord, we shall sometimes discover, that part of the peritoneal surface has not united firmly, but that a species of encysted hydrocele has taken place in it. We should now proceed to examine the structure of the testicle, as a gland. The CORD is composed of arteries, veins, absorbents, and the excretory duct of the testicle, which are all bound together by cellular membrane and the fibres of the CREM ASTER. The SPERMATIC ARTERY is the most difficult vessel to discover, as it is very small. The veins are very numerous, and easily seen. The manner of showing the absorbents will be described presently. As the vas defe- rens feels like a piece of whip-cord, compared to the other parts, there will be no difficulty in finding^ it. The cord should now be cut through, at' its exit from the abdominal canal ; but before we attempt to demonstrate the course of the vessels which convey the semen, we should in- ject some mercury into the vas deferens. The quicksilver will very seldom pass into the tubuli teetis, but will generally reach as far as the rete testis. After the injection is made, we may remove all the parts of the cord, except the vas deferens. In cutting away the veins from the body of the; testicle, we may observe, that they have a peculiar form, somewhat resembling the tendrils of a vine, whence they have been described as forming a CORPUS PAMPINIFORME ; and which is, from its pyramidal form, sometimes called CORPUS PVRAMIDALE: but this is more distinct in the testicle of the bull, or ram. We shall now see, that the vas deferens, as it passes downwards, becomes very much convoluted ; and that its convolutions lie on the body of the gland, in such a manner, as, by the ancients, to have been described as a dis- tinct body, under the name EPIDIDYMIS (didymi, or twins, being the name given to the testicles.) The first distinct turn which the epididymis takes, is on the lower part of the testicle : and here it forms a little eminence, which is called OLorujs MINOR ; while the part at wfiich the epididymis ter- minates, is called the G-LORUS MAJOR. We should now put the body of the testicle into water, and then, by cutting through the tunica albuginea, we shall see that the gland is composed of a mass, which, though apparently fibrous, may be proved, by a successful injection, to be composed of tubes. These tubuli are divided into sets, by portions of cellular membrane, which are called sepimenta. We may now tract ; the parts of the seminal duct, from the TUBULI to the vas de- ferens : by raising the coats towards the epididymis, we may, perhaps, seethe vessels called VASA RECTA, which pass from each bundle of the tubuli, to form the intricate plexus called RETE TEST-IS, and which is, continued towards the globus 94 ninjor, and gives off, within the cellular membrane covering it, the vessels which are called VAS A EFFKRKNTIA, OR VASCU- LAR CONES. The union of these vessels may be considered as the beginning- of the epididymis ; wh : ch may now be tra- ced backwards to the globus minor, as a duct very much con- voluted. As it rises from the globus minor, it is called the VAS DEFERENS, which name it retains, until it terminates in the urethra. We very frequently find a vessel called VAS ABKKRANS, passing oft' from the vas deferens, and termina- ting in a culde sac. The name of CORPUS HIGHMORIANUM is given to the part of the testicle where the vasa recta unite to the rete testis. 1 shall now describe the manner of making a few prepara- tions of the viscera of the pelvis, that may be useful to the surgeon ; some of them may be made from the same body in which the parts in the perineum have been examined. If, after dissecting the muscles, we saw through the raini of the pubes and isehium, below the part where the cura pe- nis arise, and then detach the bladder, &c. with the rec- tum, from their connections with the posterior and lower part of the pelvis, we may remove the whole of the viscera in connection with the os pubis. By a little care, we may also keep the testicles attached to the bladder, through the medium of the vasa deierentia. The bladder is then to be emptied, and the vesiculae and prostate are to be squeezed, so that all their secretions shall be pressed out. The lower part of each crus of the penis is to be opened ; a small pipe is to be fixed into one of them, through which a quantity of warm water is to be injected. The water, passing through the cellular structure, and septum pectiniforme of the cavernous body, will carry the blood with it, and escape by the hole which has been made in the other crus. A probe is to be passed along the vena dorsalis penis, towards the glans, so as to break down all the valves; and a pipe is then to be fix- ed into the vein, by which warm water is to be injected, so, H.S to wash the blood out of the spongy body. It has gene- rally been supposed, that, to distend the spongy body, it will be sufficient to inject from this vein; but I have seldom seen a good preparation made in this way. I have always found it safer to make another opening into the back part of the irlans, of sulHcient size to admit a small pipe ; so that, if the injection from the vein does not succeed, the glans and spon- gy body may be easily filled from this opening. After the H vernous and spongy bodies have been completely freed of 95 the blood and water, by being- Repeatedly squeezed, they arp in a fit state to be injected ; but previous to injecting them, a long iron sound should be passed into the bladd er : which will, in some degree, preserve the parts in their natural posi- tion. The white cold injection, or the plaster of Paris, may be injected into the cavernous body, by the pipe in its cms ; an assistant being prepared with a twisted suture, to close the opening in the other cms as soon as he perceives that all the blood and water have been pushed out by the injec- tion. When the cavernous body is sufficiently filled, the cold red injection is to be thrown into the vein on thedorsum of the penis. The asssistant must be very active in pushing the in- jection along the spongy body : but, as he will seldom suc- ceed in filling the bulb from this source, we should be prepa- red to inject, also, through the pipe in the glans. As soon as the injection in the penis has become hard, the bladder should be filled with plaster of Paris; but as the plaster would spoil a common syringe, we should make an apparatus for the purpose : this is easily done by tying a stop c ock to an ox's bladder, into which an opening has been made in the fundus, so that a quantity of plaster may be put into it. The stop-cock b^ing then passed into a pipe which has been previously fixed in the ureter, the plaster may be pushed on so as to fill the bladder. The vesiculae seminales may now be filled with mercury, by making an opening into each vas deferens, as it passes over the fundus of the bladder. We may also try to inject the testicles, by throwing the quicksilver in the opposite di- rection. The parts require very little dissection ; but it is necessary to watch them carefully while they are drying, so that they shall keep their natural position. After they have been thoroughly dried, they must be well varnished. It will be very useful to have a wax model, or cast, of tlif \irethra and bladder, in their natural situation. For this pur- pose, we should choose a subject in which the bladder is very much contracted. After the parts have been removed, with a small portion of the bone, in the same manner as the last preparation, and a rough dissection of the penis and bladder has been made, some very hard and tough wax injection should be thrown into the urethra, by the opening in the glans, and. into the bladder, by th'e ureters. When the in- j'^ction is cold> the bladder is to be opened, so that we may remove the cast. If the cavernous and spongy bodies have been previously well cleaned, we may put the penis and bladder into a strong aluminous spirit before cutting out the cast, so that when the cast is removed, the urethra and bladder shall preserve their 96 natural shape. But to make a good preparation of this kind, we should not take a cast at the same time; because the in- jection is not only liable to discolour the internal coat of the bladder, but the process of injecting will probably hurt the appearance of the parts, for the beauty of such a preparation will depend very much on its being cleanly and carefully ma- cerated. When the parts have been sufficiently macerated, some strong aluminous spirit is to be thrown into the cavernous and spongy bodies ; the urethra and bladder are also to be filled with the same fluid. The parts are then to be put, as nearly as possible in their natural relation to each other, into a glass jar full of spirits, and to remain in it until they are sufficiently hardened. The preparation is then to be taken out of the jar, and the external parts of the penis and bladder are to be more neatly dissected ; the lateral part of the urethra and bladder is then to be opened, so as to give a distinct view of the course of the canal ; bristles should be put into the seve- ral ducts. This preparation, though it may not give a very accurate idea of the size of the canal, will yet be very valuable, and should be put up neatly in a jar of spirits. I may here observe, that when we wish to preserve the bladder, &c. either in their natural or morbid state, that we should attend to the following general rules : 1st. previous to putting the part into maceration, we should dissect off all the muscles, &c. which we do not intend to preserve ; 2d. free the cavernous and spongy bodies, of blood, by repeatedly in- jecting them with water ; 3d. empty the vesiculce and the prostate by gently squeezing them ; 4th. before the part is put into the macerating pot, we should fill the bladder and the cavernous and spongy bodies with clean water ; lastly, the preparation should be suspended near the top of the jar r and the water changed twice a day. A preparation of a diseased penis and bladder may be re- moved, without even opening the body ; for if we make a long cut in the perineum, we may dissect the penis from the rami and arch of the pubes ; and then by passing a knife, directed by the ringer, into the pelvis, we may carry it round the bladder, so as to separate it from its connections internally ; and then by cutting the body of the penis across, all the parts may be easily pulled out. But if \ve are desirous of preserving the whole of the body of the penis, we ought to cut the attachment of the prepuce to the corona glandis, and then by pulling the penis from below, it will be easily separated from the loose skin. If the penis has been cut through, below the scrotum. it will be only necessary to sew up the cut in the perineum ; hut if the whole has been removed, then we must stuff tlie 97 skin of the penis with tow, having- first passed a fine thread through the inside of the prepuce, so as to give it the ap- pearance of a phymosis. When we cut out a fine example of stricture, &c. we should always endeavour to take a os pubis with the bladder. It is rather difficult to do this, unless we are at the samp time permitted to open the abdomen^ b*it an expert dissec- tor will be able to effect it, by makir^p. large incision below. Whenever a portion of bone is removed, before the parts art- sewed up, a strong cord should be passed through the obtu- rator holes, so as to hold the two sides of the pelvis togeth- er ; for if this is not done, the body will appear very much disfigured. DISSECTION Of THE PARTS IN THE PELVIS OF THE FEMALE. Although the dissection of the parts in the female pernm amis not Very interesting, in a surgical view, still it is nece?- *ury to make it ; and at the same time to attend to the names which have been given to the several parts. The Mons Veneris will be found to be only an accumula- tion of adipose substance under the integuments, and which varies in size according to the general state of the individual. The cavity which begins, as a fissure, under the mons vene~ ris, and extends to within an inch of the anus, is called vut- iw, being the name given to the opening of the vagina and urethra generally. The thick folds of integument which are continued down from the lateral parts of the mons veneris, are the Labia Externa, or Alee Majores ; their union, at the lower part of the vulva, being called the Frcenttm Labiorvm. or Fourchette : the kittle cavity above this angle of union* is sometimes called Fossa Navicufaris. The skin which is between the Fourchette and anus, is called the Anterior P? rineum ; while the part between the anus and os coccygi.* ,-;< the posterior. 98 If we separate the labia, we shall see, immediately under the mons veneris, a little projecting red body, with some loose skin covering- it ; this is the G/Vw.s> and Prepuce of the Clitoris. The two thin folds of membrane which may be traced down- wards from, the prepuce, are the Nympha* or, or Alee Mhwres, between which, and about three quarters of an inch below the clitoris, we shall discover the prominent opening of the urethra. The upper part of the vulva is called the Vest'ibu- him ; and below the level of the urethra, it is called Orijici>-m f^agince, which, in the virgin, is bounded by two folds of mem- brane, that nearly meet in the middle, and form the part cal- led Hymen : when, this is ruptured, there are little fleshy emi- nences seen on the laterol parts of the vagina, which are ge- nerally supposed to be the remains of the hymen, and are cal- led Cariinculce within the pelvis. It descends along the inferior part of the vagina and rectum. L\. Into the perineum and sphincter ani. After having- dissected the muscles, we'may remove them,' so as to expose the Crura of the Clitoris, which are attach- ed to the rami of the os pubis, nearly in the same manner as the crura of the corpus cavernosuiu are, in the male; by opening one cms we may distend the clitoris We shall find no spongy body in the clitoris; but there is something analo- gous to if, surrounding the oritice of the vagina ; it is called Rfitfi ra&culosum, or Pl.e-.cus ReUformis, or sometimes, Cor- pus Cavernosum Vagince. The parts within the pelvis should be examined, before a. perpendicular section is made. The peritoneum has been already described as passing from the rectum to the uterus, an 1 from the uterus to the bladder. If we pull up the uterus from between the bladder and rectum, we shall see the folds of the peritoneum which form the Bro'td Ligaments of the uterus ; between the duplicatures of which, we may feel the Round Ligament* which pass to the abdominal rings. The oo triit will be seen in the broad part of the ligament; and anterior to them, the Fallopian TI&PS, each of which has a floating fringed extremity, called the W>r*u* Diaboli. These parts are very seldom found in a natural state, for the uterus and its appendages are so prone to inflammation, that there aro generally adhesions between them : there are also very frequently, small tumours or hydatids attached to the ova- , rium. The section of the pelvis is to be made nearly in the same m.imier as it is directed to be made in the male. The struc- ture and form of the clitoris, the course of the urethra and of the vagina, willbe all now easily understood. If we lay open the vagina, we shall see the part of the uterus which is called the O; Lin'-(K ; the portiofi to which the vagina is attach- ed, being called the C^nix'. Upon the internal fine secreting mvnbranae of the vagina, many mucous folicles, or lacuna?, will be seen.- Tho urethra is very short, and very simple in its structure, compared with that of the male. We cannot discover any glands in it, similar to those which are connected with the neck of the bladder in the male ; but on opening the ure- thra, we shall see several lacume. The internal membrane H not muscular, but has many longitudinal folds, which per- mit of its being dilated to a great extent. Tii" 4 uterus and ovaria may now be dissected from the oth- er ,>arf>. When the cellular membrane is removed from the 100 uterus, we can comprehend how the nam.es of Cervix, Bod)/. and Fundus, have been given to its several parts. When tlit uterus i k s opened, we'shall see that it has, internally, a fleecy secreting* surface; and on each side of the upper part of the cavity, we shall discover an opening, by which we may pass bristles into the Fallopian tubes. If we make a section of the ovarium of a young- person, several small transparent ves- icles, which are supposed to be the Ova, will be seen ; they are often called Curytora Graajlana. In an older person, and particularly in one who has been pregnant, small cysts are generally found in the ovarium ; they are supposed to corres- pond to the number of ova which have escaped. Immedi- ately after conception there is a cyst of a yellow colour, whence it has been called Corpus Liiieum. The vessels in the pelvis of the- female differ considerably from those in the male, principally in there being four ad- ditional arteries of importance, viz. the two Spermatic Arteries, which run to the ovaria arid to the fundus, and to the body of the uterus; and the two Uterine Arteries, which arise from the internal iliacs, and pass to the lower part of the uterus, and inosculate freely with the spermatic arteries. Kach of these vessels has a corresponding vein- The arteries to the external parts, nearly correspond with those in the male. The JVerveswill be described with those of the Abdomen, DISSECTION THE THIGH. THE object of the student, in his first dissect ion of tin ?!.h, should be to acquire a general idea of the connections f the muscles and of the ligaments. In his second dissec- tion, he should trace the injected arteries: and in the third, the nerves, with the arteries uninjected ; he will then IK- prepared to study the parts in connection, so as to makf himself master of the surgical anatomy of the lower c> mitv. 101 I shall now endeavour to describe the best method of con- ducting* the investigation of the anatomy of the thigh and leg in this order. FIRST DISSECTION. The fascia which covers the muscles should be exposed, before they are dissected: but some care is requisite to do this neatly, as the fascia is very thin at certain points. In- deed, it is so thin on the fore and inner part of the thigh, that if the dissection is commenced at this point, it will be very difficult to avoid cutting the fascia. The leg ought, therefore, to be thrown over the other, so that an incision may be made through the skin, from the point over the tro- elmnter major, where the fascia is strong, to the head of the fibula. The skin is then to be separated from the fascia, by carrying the edge of the knife in a slanting direction. After a little of the fascia has been exposed through the whole extent of the incision, a cut is to be made through the skin only, across the lower part of the patella, and another from the trochanter to the pubes. The dissection is then to be continued, by raising the skin very carefully towards the fore and inner part of the thigh. If any muscular fibres be exposed, the dissector may be sure that he is doing wrong ; and if he looks at the inner surface of the skin, he will prob- ably see a portion of the fascia adhering to it. As the fas- cia is very strong on the back part of the thigh, it will be very easily exposed there : but I may here remark, that it will be more difficult to make a good exhibition of the fascia in a strong and fat subject, than in a thin one. After the skin is removed, we shall be able to see the muscles which are immediately under the fascia. The first muscle that will catch our eye is the Sartorius, the fibres of which should be now exposed by carrying the knife in the direction of them, from the ilium to the tibia. The muscle which is crossed by the sartorius, and runs down directly in the middle of the thigh, is the Rectus; but before we dissect, this, or the Vastus Exturnus, which is situated externally to the rectus, we should expose the fleshy part of the Ten- sor Vaginae, Femoris, or Faadnlis^ and then cut a slip of the fascia as far as to the fibula, so that it may be as a tendon to this muscle : the rest of the fascia may be then cut away, by which we shall be enabled to expose more easily, the fibres of the rectus and vastus externus. It is difficult to dissect this last muscle neatly, on account of the firm con- nection which the cellular membrane has with its lower semicircular fibres. I 2 102 We may now dissect the muscles which are on the insi:!*- of the thigh. But hefore beginning, we should separate the thighs a little, by which the thin muscle (the GraciHs} Miat passes from the pubes to the leg will be more easily dis- sected. Upon the inside of the gracilis, we shall see a mass of muscles passing from the pubes to the linea aspera ; this is principally composed of the three which form the Triceps or Adductor. To dissect the first of these, the Adduc- tor Longus, we have only to follow its fibres from the pubes to the linea aspera; but in doing this, we shall be obliged to cut through the great vessels, nerves, &c. which are passing from the pelvis to the leg ; this, however, ought to be considered of no consequence ; for in the first dissec- tion, every thing should be sacrificed to the muscles. If we continue the dissection towards the union of the os pubis and ilium, we shall expose the fibres of the muscle called Pectinalis. In tracing it down to its insertion, we shall be obliged to remove a number of vessels, glands, &c. by which we shall expose the insertion of the Psocts Magnus and Ilia- 'lift Internus into the trochanter minor. By dissecting be- tween tine pectinalis and adductor longus, we shall discover the Addiwtor Brevis, which has very nearly the same form as the pectinalis. After this, we may dissect part of the Ad- ductor Magnus ; but before we can expose all the fibres of this muscle, we must turn the leg : however, this is riot to be done. yet, for while the leg is in the present position, we should dissect the Vasius Internus, which arises from the greater extent of the thigh bone, and is inserted into the patella. When the 'dissection of this muscle is finished, the rectus may be raised and held aside, so that the Cruraeu-s, which is between the vasti, may be seen. It is difficult to separate the vasti neatly from the crurams ; for the only guide which we have, is a few vessels which pass between the muscles. After having made the origins and insertions of these muscles distinct, (for which see the annexed table,) the leg should be turned, and the muscles on the back part dissected. The first muscle which is to be dissected is the Glutens Mi-ximus. Before commencing, we should endeavour to make its fibres tense, by putting a block under the pelvis, and throwing the leg over the table and fixing it there, with the toes turned inwards. An incision is then to be made round the spine of the ilium, and another from the middle of the spine or the sacrum to opposite the trochanter major, this last incision should be slightly semicircular, with its con- cavity towards the anus. As there is no fascia covering this muscle, the fibres will now be seen, and may be fully 103 exposed by cutting boldly in the whole extent of the line of the semicircular cut, first in a direction towards the anus, and then towards the ilium. We, shall find that the muscle does not arise from the whole extent of the spine of the ilium, but that part of the spine is occupied by a portion of the Glutens Medvus, which is covered by a strong fascia. This fascia, which runs between the two muscles (and is united to the fascia lata,) is now to be divided, from the spine of the ilium to near the trochanter. By then cutting through the origin of the glutous maximus, from the iliurn and sacrum, it may be easily separated from the medius, and thrown down upon the thigh, leaving it attached, by its" insertion, to the linea aspera ; and in doing this, we should raise as much of the cellular membrane as we can, along with the muscle. If this has been done carefully, it will now be only neces- sary to dissect off the fascia from the upper and outer part of the gluteus medius, to make it distinct. When we wish to raise the gluteus medius, we should commence at the notch of the ilium, and remove the fibres from the dorsum of the ilium, as far as the anterior spinous process, by commencing at the notch we shall not endanger the Gluteus J\Iinimus so much as we should, if we w r ere to begin the separation at the upper and outer part. When the muscle is thrown down to its insertion, the Gluteus Minimus, Pyriformis, (part of which might be seen before the medius was lifted,) Gemcllus Superior, Obturator Intemus, Gemellus Inferior, and Quad- ratus Femoris, will be all partially seen. Before we can dissect these small muscles, we must turn the heel out, by which we shall stretch their fibres, which arise from the pelvis, and are inserted into the head of the femur. The great nerve which crosses the small muscles may be cut across ; or by bending the knee, it will be relax- ed, so that it may be held aside. I may also remark, that it will be necessary to turn to the inside of the pelvis, before the obturator internus aD'l pyriformis can be completely dis- sected : and that before the tendon of the Obturator Extermm can be seen, the quadratus femoris must be raised. To show the whole of the obturator, it will be necessary to remove the muscles which lie on the fore part ; but this should not be done, until all the other muscles are fully examined. Be- fore the muscles on the back of the thigh are exposed, the student should refer to the table of origins and insertion^, for a description of the muscles which he has just dissected. The limb is to be then extended, and laid on its fore part. The dissection should be begun on the inner part, by dis- secting behind the gracilis, by which we shall come upon the Semitendinoeus that runs from the ischiumto the inside 4 of the 104 tibia ; between it and the gracilis, we shall find some fibres of the adductor inagnus; these, however, at present, we should neglect. In dissecting the origin of the semitendino- sus, we shall discover the origin of another muscle which passes towards the outer part of the leg ; and if we follow it, we shall find that it is united with a set of fibres which arise from the back part of the lineaaspera, and that the two por- tions, when united., pass down to the head of the fibula; tliis is th j Biceps, and is the muscle which forms the outer ham-string. Before removing the fat and the nerve and ar- tery which are in. the ham, between the semitendinosus and biceps, we should dissect the muscle that arises from the ischium, below the semitendinosus, and is inserted into the head of the tibia. This muscle is distinguished from the semitendinosus by the name of Semimembranosus, which is given -to it, from its membranous ^appearance. These two last muscles form the inner ham-string. After removing all the vessels, nerves, & c. from the ham, the back part of the adductor magnus maybe easily exposed through its whole extent: and the opening in it through which the artery passes from the fore part of the thigh into thoham, will be also seen. In making this last dissection, we shall necessarily expose the origins of the GaMrocnemius; but the muscles of the leg should not be traced, until we have made ourselves com- pletely master of the anatomy of the muscles of the thigh, nor should the skin be raised, for as long as the muscles are covered by the skin, they will keep fresh. The dissection of the muscles of the leg is to be begun by making an incision from below the patella, along the spine of the tibia, to the great toe, and another along the middle of the back of the leg, from the knee to the heel ; the skin only, is then to be removed. This will expose a fascia, which, though very strong on the fore part of the leg, be- << ines still so much stronger at the ankle, in consequence of additional cross slips of fascia, that it is there described as forming particular ligaments, winch are called Annular Liga- rntnts. The fascia upon the fore part of the foot is very thin, being little more than cellular membrane. When the skin is taken off from the back part, very little fascia will be seen covering the large muscle, the gastrocne- mius ; but by continuing the incision from the heel along the sole of the foot, we shall discover a very strong fascia, which is called the Plantar Jlponeurosis. To dissect this neatly, we should pull the thick skin of the foot forcibly to each side, and carry the knife, in a slanting direction, close upon the fascia. 105 We may now proceed to dissect the muscles. The exter- nal muscle of the calf, the Gastrocnemius , is very easily. shown, for we have only to carry the knife in the direction of its fibres. In dissecting this, the edge of the next muscle, the soleus, will be exposed : but before it can be fairly seen, the origin of the gastrocnemius from the internal condyle. must be raised, and then we shall also see the small muscle (Plantaris) which arises in union with its external origin, and runs down to the inside of the os calcis. In this view, the Popliteus, which arises from the lower part of the exter- nal condyle, and runs to the tibia, will also be exposed. To show the tendo Achillis, which is formed by the Gastrocnemius^ Soleus, and Plantaris , we must remove a large quantity of fat, which is situated between it and the next layer of muscles. The soleus may then be raised from its origins, from the tibia and fibula, and turned down with the gastrocnemius and plantaris, to their attachment to the os calcis. This will enable us to see the deep layer of muscles, which are covered by a strong fascia; but it will not be possible to trace these muscles to their insertions, un- til those of the foot are dissected. By cutting away the fascia, and all the vessels and nerves, with their surrounding cellular membrane, the origins of these muscles will be seen, viz. of the Flexor Pollicis Longus, principally from the fibula the Fexor Longus Digitorum, from the tibia and, between the two, the Libialis Posticu^^ which has an ex- tensive origin from both bones. Each of these muscles passes behind the inner ankle, and is bound down by distinct annular ligaments : but before tracing them farther, we must dissect the muscles on the fore part of the leg. The fascia adheres very strongly to the muscles which arise from the tibia, and particularly to the Libialis Jlnticus, so that it is rather difficult to take it off neatly. In removing it, we must take care that we do not cut through the annular ligaments at the ankle. If we trace thq tibialis anticus, we shall find it pass to the internal cuneiform bone. The muscle which iies close upon it, and arises principally from the fibula, is the Extensor Communis D-igitorum, which passes to all the toes except the great toe. The separate extensor for the great toe (Extensor Pollicis Proprius) arises between the two last muscles. Upon the outer edge of the extensor commu- nis digitorum, there are three muscles, which, as they rise from the fibula, are called peronei : the first is called Peroneus Longus, and may be traced down, under the outer ankle, as far as the os cuboides, but here its tendon passes into a groove, and then across the sole of the foot, to the cuneiforme internum : this will be seen when the muscles of the foot are 106 dissected. The Peroneus Secundus, or Brevis, runs in the same Khe along- the fibula, but is inserted into the rnetatarsal bone of the little toe. The Peroneus Tertins is generally so much connected with the fleshy part of the extensor commu- nis digitorum, that it is difficult to separate them at this part ; we should therefore first dissect its tendon, which is inserted into the metatarsal bone of the toe next the little toe. As there is only one muscle on the fore part of the foot, (the Extensor Brevis Digitorum,] there can be no difficulty in dissecting it ; but it is not so with those in the sole of the foot, for the muscles there, are not only particularly com- plicated, but the difficulty is increased in consequence of several of the tendons of the muscles on the leg running be- tween them. The plontar fascia is to be first cut through, about the middle, and then the one half is to be raised towards the heel, and the other towards the toes ; but; in removing it, we must carefully avoid lifting the origin and insertions of the Flexor Digitorum Brevis, which arises, in part, from the fascia. After this muscle is dissected, the Abductor Pollicu\ -and Abductor J\finimi Digiti, which are on each side of the foot, are to be exposed ; then the flexor digitorum brevis is to be cut through at its origin, and is to be carried towards the toes ; this will expose the. tendon of the long flexor, to which the Flexor Accessorius, which arises from the os calcis, is attached. From the fore part of the same tendon, the Lwnbricales will be seen passing to the toes. When th-^e tendons are cut, and turned, with the lumbricales, towards the toes, the tendons of the tibialis posticus, and of the pero- neus longus, will be seen crossing the foot. We may now easily dissect the Flexor Brevis and Adductor Pollicis on the out? side, and the Flexor and Adductor Minimi Digiti on the other. When these are made out, there will only remain the Trans- yersalis- and the Interossei. It will, perhaps, assist us in recollecting these muscles, if we arrange them into classes. This may be done in several ways, but to all of which there are many objections. The following plan is offered, although it is also very faulty. To pull the thigh backwards, there are three muscles, viz. .the Glutens Jftaximus, Gluieus JWedius, and Glutens JWmimim^ which have, as antagonist muscles, the Psoas JWagnvs and Hi item Infernus. The class of muscles which more particularly roll the thigh, is composed of the Pyriformis, Gemellus Superior Obturator Internus, Gemellus Inferior, O'jiurator Extertu'*. and Quadratus Femo-ris. 107 CLASSIFICATION OF THE MUSCLES OF Tlif THIGH, LEG, AND FOOT. MUSCLES OF THE THIGH. The three superficial muscles, Fascialis, Sarlorhts> and Gracifis, may be classed together. If these three are removed, twelve muscles will remain on the thigh ; of which four are inserted into the patella, and extend the leg, viz. the Redux, J^astus Externus, Fastw inter- WAV, and Crurceus. Four bend the leg, and are inserted into the tibia and fibula, viz. Semite-ndincsus, Scmimeinbrano&tis, Biceps^ and Popliteus. And four, which pull the thighs together (ad- ductors,) are inserted into the linea aspera, viz.- Pectinate, Ad- ductor Longus, Adductor Brevis., arid Adductor J\lagnus. MUSCLES OF THE LEG. As the muscles which bend the toes are situated on the back part of the leg, and those which bend the foot are on ,- the fore part, it is not possible to make a good arrangement according to the uses of the muscles ; therefore, in the fol- lowing plan, the use of the muscles is entirely neglected, the arrangement being made according to their relative situations. There are twelve muscles on the leg, which may be di- vided into two great classes, viz. into six on the fore part, and the same number behind, both of which may be subdi- vided : the six on the fore part, into three on the fibula, viz, Peronefo Z/ongits, Peron-evs Brevi^ and Perorwu* Tertiior and three, more directly on the fore part, Tibialis Anticus, Extensor DigitorurnCornmunix, and Extensor Pollicis Propri us ; the six on the back part, may be still more easily subdivided into the three which are inserted into the os calcis, viz. Gagtrocnemitts, soleu9)WQ&Ptartari$ and into the three deep muscles, Tibia- Us PosticitSy Flexor Digitorwn Longus, and Flexor PolliciK Longus. MUSCLES OF THE FOOT. As the muscles which are on the sole of the foot are so dif- ficult to remember, any arrangement which will facilitate the recollection of them, must be acceptable. I have classed the three muscles belonging to the great toe, together, viz. the Abductor ', Ftexor Brcvis, and the Adductor Pollici* ; then the three belonging to the little toe the Abductor, Flexor ParwiSj and Adductor Minimi Digiti; in the middle of the sole of the foot there are the Flexor Brevis Digitorwn, the Flexor Accesso- rius, and the Lumbricafa (as one muscle.) After these nine xnusctes are removed, there are only the TrcwmersaUs and tho 108 Interossei Interni, on the sole of the foot ; and on the fort- part, the Extensor Brevis Digitorum and the Interossei Externi, The following table of the origins and insertions of the muscles, is given nearly in the same order in which the muscles have been arranged. GLUTEUS MAXIMUS. OR. 1. The posterior part of the spine of the os ilium, near the sacrum. 2. From the con- vexity of the os sacrum. 3. From the sacro^ischiatic liga- ment. 4. From the os coccygis. IN. By a strong broad tendon, under which is a largf ; bursa, into the upper and outer part of the linea aspera. USE. To carry forward the trunk upon the thigh. GLUTEUS MEDIUS. OR. 1. The anterior superior spi- nous process of the os ilium. 2. The edge of the spine of the ilium. 3. From the back part of the dorsum of the ilium. This muscle is covered by a strong fascia, from which many of its fleshy fibres arise. IN. By a broad tendon into the trochanter major. USE. To draw the thigh bone outwards, and a little bark- wards; to roll the thighbone outwards, especially when it is bended ; to assist the former muscle. GLUTEUS MINIMUS. OR. A ridge that is continued from the superior anterior spinous process of the os ilium, and from the middle of the dorsum of that bone, as far back as its great notch. IN. Into the fore and upper part of the trochanter major. USE. These two last muscles assist the maximus, and, an their size indicate, they are muscles of the trunk. They move the trunk forward by a succession of actions. N. B. The SOAS and ILIACUS have been described at page 48. PYRIFORMIS. OR. From the 2d, 3d, and 4th portions of the sacrum. A few fleshy fibres from the OB ilium. It passes out of the pelvis along with the posterior crural nerve. IN. By a round tendon, into the root of the trochanter major. USE. To roll the thigh, and twist the body forward, on the ball of the great toe. N. B. 'rtie COCCYGEUS has been described with the muscles of tbe perineum, at page 88. OBTURATOR INTERNUS. OR. The os pubis and ischium* where they form the foramen thyroideum; and from the 109 ** obturator ligament, a flattened tendon passes out of the pel- vis, between the posterior sacro-ischiatic ligament and tube- rosity of the osischium ; it passes ever thecapsular ligament of the thigh bone, where it is enclosed, as in a sheath, by the gemini muscles. IN. The pit at the root of the trochanter major. USE. To roll the thigh bone outwards. GEMINI, OR GEMELLUS SUPERIOR AND INFERIOR. OR. The Superior, from the spinous process ; the Inferior, from the tu- berosity of the os ischium ; and from the sacro-ischiatic liga- ment. (They are united by a tendinous and fleshy membrane, over which the tendon of the obturator interims muscle plays.) IN. The cavity at the root of the trochanter major, on each side of the tendon of the obturator internus, to which they adhere. USE. The same as the last. QUADRATUS FEMORIS. OR. The outside of the tuberosi- fryof the os ischium, (runs transversely.) IN. The intertrochanteral line or ridge. USE. To roll the thigh outwards. OBTURATOR EXTERNUS. OR. Fleshy, from the lower part of the os pubis and ischium; surrounds the foramen thyroi- deum. A number of its fibres, arising from the membrane which fills up that foramen, are collected, like rays, towards a centre, and pass outwards round the root of the cervix of the os femoris. IN. By a strong tendon, into the cavity at the root of the tvochanter major. USE. To roll the thigh bone obliquely outwards. MUSCLES ON THE FORE PART OF THE THIGH. TENSOR VAGINJE FEMORIS, OR FASCIALIS. OR. The ex- ternal part of the anterior superior spinous process of the os ilium. IN. Into the fascia which covers the outside of the thigh. and through it into the outside of the knee. USE. It is an abductor. SARTORIUS. OR. The anterior superior spinous process of the os ilium ; soon grows fleshy, rung down for some space upon the rectus, and going obliquely inwards, it passes over the vastus internus, and, about the middle of the os femori 4 over part of the triceps ; it runs down further between the tendon of the adductor magnus and that of the muscle. K 110 IN. By a broad and thin tendon, into the inner side of the tibia, hear the inferior part of its tubercle. USE. To draw the leg inward, and to bend the knee joint. GRACILIS. OR. By a thin tendon, from the os pubis, near the symphysis of these two bones; soon grows fleshy, and, descending by the inside of the thigh, is IN. Inner and fore part of the tibia, under the sheath of the sartorius. USE. It is an adductor and flexor. Under the name of the TRICEPS ADDUCTOR FEMORIS, are comprehended three distinct muscles, viz. ADDUCTOR LONGUS FEMORIS. OR. On the inside of the pectinalis, from the upper and fore part of the os pubis, and ligament of the symphysis. IN. The upper third of the linea aspera. ADDUCTOR BREVIS FEMORTS. OR. The os pubis, near the. symphysis, and lower than the last muscle. IN. The inner and upper part of the linea aspera, from a little below the trochanter minor, to the beginning of the in- sertion of the adductor longus. ADDUCTOR MAGNUS FEMORIS. OR. 1. From the ramus of the os pubis; 2. from the ramus and the tuberosity of the os ischium, as low down as the tuberosity. IN. 1. The whole length of tke linea aspera; 2. into a ridge above the internal condyle of the os fernoris; 3. by -a long round tendon (which is united to the vastus internus) into the upper part of the condyle. USE of these three muscles, or Triceps, to bring the thigh inwards and forwards, as in clinging to the saddle ; and, jii some degree, to roll the toe outwards. The pectinalis, which lies between the adductor iongus and brevis, may be classed with them. PECTINALIS. OR. Broad and Meshy from the upper ancf anterior part of the OB pubis, immediately above the fbramew thyroideum. IN. Into the anterior and upper part of the linea aspera of the os femoris, a little below the trochanter minor, by a flat and short tendon. USE. To bring the thigh upwards and inwards. QUADRICEPS EXTENSOR CRURIS, is composed of the fen* following muscles .* RECTUS. OR. 1. The lower and anterior spinou* jroeesg of the os ilium; 2. tendinous from the dersum of the ilium, a little above the aeetabuhim. IN. The upper part of the patella, and through the medium of the patella, and its ligament, into the anterior tubercle of the tibia. USE. To extend the leg, or raise the body. VASTUS EXTERNUS. OR. 1. The root of the trochanter major; 2. the whole length of the linea aspera, by fleshy fi- bres which run obliquely forwards to a middle tendon, where they terminate. IN. The patella ; part of the muscle ends in an aponeuro- sis, which is continued down on the leg, and is firmly fixed to the head of the tibia. USE. To extend the leg, or raise the body from the seat. VASTUS INTERNUS. OR. 1. The fore part of the os femo- ris; 2. root of the trochanter minor; 3. almost all the inside of the linea aspera; the fibres run obliquely forwards and downwards, and it is fleshy considerably lower than the last. IN. The patella ; part of this also ends in an aponeurosis, which is continued down the leg. USE. To extend the leg, or raise the body. CRURJEUS. OR. 1. From between the two trochanters of the os femoris ; 2. it adheres firmly to all the fore part of the os femoris, and joins the vasti muscles. IN. The patella, (behind the reef as.) USE. To assist the three last muscles. MUSCLES LYING ON THE BACK OF THE THIGH. FLEXORS OF THE LEG. SEMTTENDINOSUS. OR. The posterior part of the tubero- sity of the os ischium, in common with the long head of the biceps, to which it is connected by fleshy fibres to the extent of two or three inches. . l.\. The ridge, and inside of the tibia, a little below its tubercle. USE. To bend the leg. SBMIME,MBJIANOSUS. OR, B^ a strong tencon, from the upper and backmost part of the tuberosity of the os ischium. IN. The inner and back part of the head of the tibia. USE. To bend the leg. N, B. The two last form the inner ham-string. BICEPS FLEXOR CRURIS. OR. (Two distinct heads,) the first, longus, in common with the semitendinosus, from the back and outer part of the tuberosity of the ischium ; the se- cond, breyis, trom the linea aspera, beginning a little below 112 the insertion of the gluteus maximus, it continues to take its- attachment, till within a hand's breadth of the condyle. IN. Head of the fibula and ligaments. USE. To bend the leg. POPLITEUS. OR. The lower and back part of the external condyle of the os femoris, on the back of the joint. IN. The ridge on the inside of the tibia, a little below its head. USE. To assist in bending the leg. MUSCLES LYING ON THE BACK OF THE LEG. GASTROCNEMIUS EXTERNUS, OR GEMELLUS. OR. 1. The upper and back part of the internal condyle of the fernur, and from that bone, a little above its condyle; 2. the second head arises.tendinous from the upper and back part of the external condyle of the femur. After forming two beautiful bellies, which are united by a middle tendon, the muscle terminates in the tendo Achillis. SOLE us, OR GASTROCNEMIUS INTERNUS. OR. (Two ori- gins.) 1. The upper and back part of the head of the fibula, continuing to receive many of its fleshy fibres from the pos- terior part of that bone, for some space below its head. 2. From the back part of the tibia, lower down than the in- sertion of the popliteus. The flesh of this muscle, covered by the tendon of the gemellus, runs down, nearly to the lower end of the tibia by the tendo Achillis. IN. Into the backmost part of the os calcis, by the projec- tion of which these muscles gain a considerable leve*r power. USE. To extend the foot. PLANTARIS. OR. The upper and back part of the exter- nal condyle of the femur; it adheres to the ligament of the joint. It passes under the gastrocnemius, and forming a long slender tendon, then runs down by the inside of the ten- do Achillis. IN. The inside of the os calcis. USE. From its delicacy, and insufficiency to assist the last muscles, it is supposed to have a use in pulling the capsular ligament of the knee from between the bones. THE THREE DEEP MUSCLES, ARE THE TIBIALIS POSTICUS. OR. 1. The fore and upper part ot the tibia, just under the process which joins it to the fibula. 2. Then passing through a perforation in the upper part of the interosseous ligament, it continues its origin from the back part of the fibula next the tibia. 3. From near one hall' 113 te upper and back part of the tibia. 4. From theinteros- .seous ligament, the tendon passes behind the malleolus interims. IN. Spreads wide in the bottom of the foot, and is inserted into the os cuneiforme internum and medium ; and also to the os calcis, os cuboirles, and to the root of the metatarsal bone that sustains the middle toe. USE. To extend the foot, and to turn the toes inwards. FLEXOR LONGUS DTGITORUM PEDTS PERFORANS. OR. The back part of the tibia, some way below its head, and near the entry of the medullary artery; from this, it is continued down the inner edge of the bone ; also, by tendinous and fleshy fibres, from the outer edge of the tibia ; between thi* double order of fibres the tibialis posticus muscle lies en- closed. Having passed under two annular ligaments, it then passes through a sinuosity at the inside of the os calcis, and, about the middle of the sole of the foot, divides into four ten- dons, which pass through the slits in the perforatus. Just before its division, it receives a considerable tendon from that of the flexor pollicis longus. IN. Into the extremity of the last joint of the four lesser toes. USE. To bend the last joint of the toes. This muscle is assisted by the accessorius. See dissection of the sole of the foot. FLEXOR LONGUS POLLICIS PEDIS. OR. By an acute, ten- dinous, and fleshy beginning from the posterior part of the fibula, some way below its head, being continued down the same bone, almost to its inferior extremity, by a double order of oblique fleshy fibres ; its tendon passes under an annular ligament at the inner ankle. IN. Into the last joint of the great toe. It generally sends a small tendon to the os calcis. USE. To bend the last joint of this toe. MUSCLES ON THE FORE PART OF THE LEG. PERONEUS LONGUS. OR. From the head, and whole length of the fibula, as far down as to within a hand's breadth of the ankle. The tendon passes through a channel at the outer ankle, at the back of the lower head of the fibula ; it then runs along a groove in the os cuboides, across the sole f the foot. IN. The root of the metatarsal bone that sustains the great foe, and the os cuneiforme internum. USE. To move the foot outwards, and t* press dawn the 5a!l of the great toe. 114 PERONEUS BREVIS. OR. From the middle and lower par* of the fibula; from the fibula, above the middle; from the outer side of the anterior spine of this bone ; and also from its round edge externally, the fibres running obliquely out- wards, towards a tendon on its external side. It sends off a round tendon, which passes through the groove at the outer ankle, being there included under the same ligament with that of the preceding muscle ; and a little farther, it runs through an appropriate sheath. IN. The root and external part of the metatarsal bone that; sustains the little toe. USE. To direct the foot outwards, and by pressing the ball of the great toe to the ground, to assist in carrying forwards the whole body. PERONEUS TERTIUS. OR. The middle of the fibula, down to near its inferior extremixity ; the tendon passes under the annular ligament. IN. The root of the metatarsal bone that sustains the little toe. USE. To assist the other peronei muscles. N. B. The belly of this muscle is united to the extensor digitorum. TIBIALIS ANTICUS. OR. 1. The process of the tibia to which the fibula is connected above. 2. The outside of the tibia. 3. The upper part of the interosseous ligament. IN. The inside of the os cuneiforme internum, and nearer extremity of the metatarsal bone that sustains the great toe. USE. To bring the foot to right angles with the leg. EXTENSOR LONGUS DIGITORUM PEDIS. OR. 1. The ouU .side of the head of the tibia. 2. The head of the fibula, where it joins with the tibia, and spine of the fibula. 3. From the interosseous ligament. 4. From the tendinous fascia which covers the outside of the leg. IN. The root of the first bone of each of the four small toes, and is expanded over the upper side of the toes, as far as the root of the last bone. USE. To extend the four lesser toes. EXTENSOR PROPRIUS POLLICIS PEDIS. OR. Beginning- some way below the head and anterior part of the fibula along which it runs to near its lower extremity, connected to it by a number of fleshy fibres, which descend obliquely towards a tendon. IN. The first and last joint of the great toe. USE. To extend the great toe. 115 MUSCLES OF THE SOLE OF THE FOOT, AFTER; DISSECTING THE PLANTAR APONEUROSIS, SHORT MUSCLES OF THE GREAT TOE, ABDUCTOR POLLICIS PEDIS. OR. The inside of the pro- tuberance of the os calcis, where it forms the heel: and from the same bone, where it joins wtth the os naviculare. IN. The internal os sesamoideum, and root of the first joint of the great toe. USE. To pull the great toe from the rest ; but its power is lost by the use of shoes. FLEXOR BREVIS POLLICIS PEDIS. OR. 1. The under and fore part of the os calcis, where it joins with theos cuboides, 2. From the os cuneiforme externum ; it is inseparably uni- ted with the abductor and adductor pollicis. IN. The external sesamoid bone, and root of the first bone of the great toe. ADDUCTOR POLLICIS PEDIS. OR. 1. The os calcis. 2. The os cuboides. 3. The os cuneiforme externum, from the root of t-he metatarsal bone of the great toe. USE. To bring this toe nearer the rest ; but by the pres- vstire of the shoe, its power is much reduced. MUSCLES OF THE LITTLE TOE. ABDUCTOR MINIMI DIGITI PEDIS. OR. Side of the pro- tuberance of the os calcis, and from the root of the metatar- sal bone of the little toe. IN. The root of the first bone of the little toe. USE. To draw the little toe outwards from the rest ; and also to bend the toe. FLEXOR BREVIS MINIMI DIGITI PEDIS. OR. 1. The os cuboides, near the furrow for the tendoji of the peroneus Ion gus. 2. The outside of the metatarsal bone that sustains this toe. IN. The first bone of this toe. USE. To bend the toe. N. B. There is no proper ADDUCTOR MINIMI DIGITS but we may class one of the Internal Interossei as an Adductor. FLEXOR BREVIS DIGITORUM PEDIS, PERFORAUS. OR. The inferior and back part of a protuberance of the os calcis (be tween the abductor of the great and little toes.) It sends off four tendons, which split, for the transmission of the ten- dons of the flexor longus, 116 I.N. The second phalanx of the four lesser toes. (Tik- tendon of the little toe is often wanting.) USE. To bend the second joint of the toes. PLEXOR DIGITORUM ACCESSORIUS, OR MASSA CARNEA. .1 ACOBI SYLVII. OR. The sinuosity at the inside of the os calcis, the fore part of the bone. IN. The tendon of the flexor longus, just at its division into four tendons. USE. To assist the flexor longus, and to change the direc- tion of its operation. LUMBRICALES PEDIS. Are four in number. Each has ite origin thus : OR. The tendon of the flexor profundus, just before its division, and near the insertion of the massa car- nea. IN. The inside of the first joint of the toe. It is lost in the tendinous expansion that is sent from the extensor tendon to cover the upper part of the toe. USE. Flexors. TRANSVERSALIS PEDIS. OR. The extremity of the meta- tarsal bone of the great toe ; the internal os sesamoideum of the first joint (adheres to the adductor pollicis.) IN. The anterior extremity of the nietatarsal bone of the little toe, and ligament of the next toe. USE. To contract the foot, by bringing the great toe and the two outermost toes nearer each other, and to support the lateral arch of of the foot. INTEROSSEI PEDIS LNTERNI. The first, which is called Adductor JVfedii DigUi Pedis, arises from the inside of the root of the metatarsal bone of the middle toe* and is inserted into the inside of the root of the first joint of the middle toe : f he two others, which are called Adductor Tertii Digiti Pedis MTU! Adductor Minimi Digiti, rise in the same manner. MUSCLES SITUATED ON THE FOSIE PART OF THE FOOT. EXTENSOR BREVIS DIGITORUM PEDIS. OR. The fore and upper part of the os calcis ; it divides into four portions, which send tendons that pass over the upper part of the foot, under the tendons of the former. IN. The tendinous expansion which covers the toes ex- cept the little one. USE. To assist in extending the toes, and somewhat hange the direction of the force of the long extensor- 117 INTEROSSEI PEDIS EXTERNI BICIPIT*:S. There are four of ihese muscles, each of which arises, 1>y two origins, from the metatarsal bones, between which they lie. The following names have been given to them : Abductor Indicis Pedis ;-- Adductor Indicis Pedis ; Abductor Medii Dig-it i Pedis ; Abductor Tertii Digiti Pedis. DISSECTION OP THE LIGAMENTS OF THE PELVIS, AND OF THE JOINTS OF THE LOWER EXTREMITIES. THE dissection of the ligaments of the upper part of the pelvis is generally a very unpleasant task for the young stu- dent, because it is seldom made until the parts are almost putrid. If the muscles are much decayed, they should be remov- ed, and the pelvis put into water for a day or two. But the best method of proceeding is, either to remove the muscles while they are fresh, and to dissect the ligaments of the pel- vis before the muscles below the knee are examined, or to allow the parts to lie in water until the muscles become so soft that they can be easily separated from the ligaments. The ligaments of the pelvis may be divided into several distinct sets : 1st. those which unite the vertebrae and the sacrum ; 2d. the ligaments which run from the ilium to the vertebrae : 3d. those which are between the ilium and the sacrum ; but all these are of very trifling importance, com- pared to those which are between the bones at the outlet of the pelvis. The ligaments which are between the lumbar vertebrae and the sacrum, are so similar to those of the spine, that I shall omit the description of them here. But if we pull the spine from the ilium, before we remove the muscles which lie between the ilium and the last vertebr, we shall liiid 118 thai the bones are held together by two ligaments, one of which passes from the crest of the ilium to the trans- verse process and body of the last lumbar vertebra, and is called Ligamentum Anticum Superius. This ligament is often of a triangular form> in consequence of a small portion of it passing also to the fourth vertebra. The Ligamentum Anticum Inferius runs from the same point as the other, to- wards the union of the last vertebra with the sacrum. The principal connection between the sacrum and ilium, is at the sacro iliac symphysis, through the medium of a fibro cartilaginous structure, which is sometimes called the Sacro Iliac Ligament ; but this cannot be seen until all the ligaments are cut through, and the bones torn asunder. Some small ligaments will be seen, after the muscles which lie between the sacrum and ilium are removed. These ligaments have been commonly called L-igamenta Dorsalia raga ; but by Weiibrecht) that indefatigable dissector of ligaments, they have been divided into three distinct portions, and if we have patience, enough we may do the same. We shall find one portion passing from the superior posterior spinous pro- cess of the ilium, to the transverse process of the fourth bone of the sacrum ; this, Weitbrecht has called the Liga- mentum Posticum Longum Ossis I Hi. By raising this liga- ment, the Ligamentum Posticum Breve Ossis Ilii will be found running from the same point to the third bone : and from the internal part of the same spine, the Ligamentum Laterale parses to the inferior margin of the first bone of the sacrum. The most important ligaments are those situated at the outlet of the pelvis : to dissect these, it is only necessary to remove the muscles. We shall first expose the Sacro Ischia- tic-urn Majiis, or Posterius, which arises from the posterior part of the crest of the ilium, and from the sides and poste- rior part of the sacrum and os coccygis, and is attached to the tuberosity of the ischium. The portion of this ligament which runs up towards the superior posterior spinous process of the ilium, is called the Superior Appendix; but a more important portion, is that which may be traced from the tu- berosity of the ischiurn, towards the ramus of the pubes. It is called the Productio Falciformis of Winslow. (a) (a) Since no particular description of the Triangular Liga- ment of the Urethra has been given : from its connexion with what is called the productio falciformis of Winslow and from being really a ligament of the pelvis I shall introduce it in this place. This ligament then is situated across the arch and between the rarni of the pubes; is connected above to the under part of the annular or capsular of the symphy 119 The Lig amentum Sacro IscHaMcwn M'ntis, or will be seen above the last, rising from the sides of the sa- crum and os coccygis, and attached to the spine of the ischium. The [os coecygis is united, in early life, to the sacrum, bv ligaments analogous to those of the bodies of the vertebrae ; but no distinct ligaments can now be shown, for the bands covering the anterior and posterior parts of the bone, are merely continuations from the Ligamenta Vaga^ which con- nect the bones of the sacrum. The ossa pubis are united together by an intermediate car-= tilage, which has a considerable similarity to the interverte- bral substance. It has been called the Commissvra O^ium Pubit, and is strengthened by a ligament, to which the name ofAnnulus Ligamento&us has been given. The obturator foramen is all closed by the JWe-mbrana Ob- iurans, except a small portion at the upper part, which is for the transmission of the obturator artery and nerve. The Pouparfs Ligament is sometimes described as one holding the bones of the pelvis together. It is curious that Weitbrecht calls this the <( f^exatusimum Ligamentum." It may be truly so called still. Poupart first described it, from the dissection of a goat; and since his time, up to this day, there has always been a dispute, whether it is a distinct liga- ment, or only part of the tendon of the external oblique muscle. Weitbrecht considers it as a separate ligament ; and this is probably the most correct view. But we" shall not say morf upon it, as it has been already sufficiently dwelt upon in the description of the abdominal muscles. (a) feis ; and is about an inch and an half in depth. It is about half an inch thick ; but, gradually lessening, its lower edge is thin. At this part near the bone on each side the produc- tio falciformis is continuous with the ligament, by which it appears to be drawn down towards the tuberosities of the ischia ; and from the attachment of the sphincter ani, with the muscles of the perineum, into a middle point at the un- der edge of this ligament the appearance of a double arch is exhibited. By this connection the triangular ligament serves "to support the viscera of the pelvis, and assist in the joining* at the synisjphysis pubis. At about the centre of the ligament is a hole fdr the passage of the urethra from the bulb, and Cowper's glands are to be found in the substance of the liga- ment on each side this opening, which accounts for its greater thickness at it3 upper part. (a) I think it right to introduce here a description of the Arch, fo? from its structure stncl connexions ; i( 120 TABLE OF THE LIGAMENTS OF THE PELVI& (ON THE UPPER PART.) 1 . Ligamentum Anticum Superins. 2. ' Inferius. 3. _* Sacfo Iliacum. 4. Ligamenta Dorsalia Vaga? divided info-*- a. Ligamentum Longum Ossis Ilii. b. = Breve. c. Laterale. may be enumerated with the ligaments of the pelvis, with equal propriety as Poupart's ligament. For this purpose, I shall transcribe from my Surgical Anatomy, published New- York, 1822. k ' I am perfectly aware, that in the majority of instances, what I am about now to delineate, has the appearance of unity with Poupart's ligament: but from having so often seen them separate, I have ventured at a method of description, which is a little out of the common order pursued by anato- mists. I am not, however, altogether without precedent for this plan, since Mr. Hey, in the iirst edition of his Practical Observations on Surgery, had adopted it ; and moreover, as Mr. Robert Liston, of Edinburgh, has written a book solely upon the subject of the crural arch. In the course of my late dissections, I have frequently been led to a very careful examination into the ligamentous structure at the groin ; in order that I might satisfy myself of the particular disposition of those tendinous fibres, whicli form the ultimate seat of stricture in femoral hernia. As was to be expected, I found the ligament, of Poupart, running in a straight direction, after the parts connected with it were in a relaxed state ; but I also observed, what has been described as the third insertion of the external oblique muscle, to be a considerable ligamentous band, run- ning in an arched course, in the direction of the anterior part of the crural sheath ; having its inner attachment from the ligament covering the spinous ridge of the pubis, about an inch from the tuberosity ; and outwardly, its fibres seemed to seek connexion with the inferior anterior epinous process of the ilium ; by going between the psoas and iliacus muscles* as they come out of the pelvis. This crural arch at its inner and upper part, I have seen in many instances, quite distinct from Poupart's ligament, having only a membraneous joining with it, similar to that uniting the two columns of the tendon, of the external oblique, as they go to form the external ring. At about the centre of 121 * (6N THE LOWER PART.) t. Ligametituni Sacro Ischiaticum J^Iajus^ with its two appendages, Appendix ^Superior, and Productio Falciformis of Winslow. 2. Ligamentum Sacro Ischiaticwn JNiinus* 3. Ligamenta Vaga. (On the inside of the sacrum.) 4. Ccnnmissura Ossium P-ubis. 5. Annulus Ligamentosus. 6. Memhrana Obturans. 7. Liganientum PoupartiL this arch, however, the fibres become in close contact with Poupart's ligament, and firmly adhere to it, by which their arched course is sustained; yet the fibres are not incorpora- ted here with those of Poupart's ligament, as can be de- termined by maceration. After passing this centre, th" fibres of the crural arch again separate from those of Pou- part's ligament, and disappear between the psoas and iliacus interims muscles. Thus we have a ligamentous structure distinct from Poupart's ligament, distant from the tendon of the external oblique ; having attached to it in close union the process of fascia transversalis that descends into the thigh; and prescribing limits to the mouth of the cru- ral sheath. It is this which Gimbernat found only necessary to divide, to relieve the stricture in femoral hernia ; and it is this also, to which Mr. Hey, in the first edition of his Surgi- cal Observations, has given the name of femoral liga- ment. Now, although the separation between the fibres, of what I have here called exclusively, the crural arch ; and Poupart's ligament, is not always to be found equally dis- tinct ; yet the arched course of the one set, I believe to bt> always present, in opposition to that of the other, which from their nature of attachment, must run in a direct line. That the crural arch is always to be found, is proved by the acknowledged invariable oval shape of the mouth of the crural sheath, when beheld from the abdominal aspect. To the fact then : that, immediately in contact with and ever the anterior part of the mouth of the crural sheath, binding it down from the linea-ileo-pectinea, at about an inch from the tuberosity of the pubis, to the os ilium below the superior spinous process ; are tendinous fibres running in as arched direction, and placed, throughout their course, from being in contact with, to within the distance of L 122 There is very little dissection necessary, to show the liga- ments of the hip joint, for if all the muscles* are raised, the only ligament which surrounds the joint will be seen. This is a very strong ligament, arid is called the Ligctmentum Cap- mlare. It takes an attachment round the acetabulum, and descends to the line between the trochanters, in front, and to the same extent on the back part, so as to embrace the whole of the head and neck of the bone. The ligament is strength- ened, on the anterior part, by a band of fibres which run from the anterior spinous process of the ilium, form iheLiga- mcntum Accessorium Anticum. A similar band may be seen on the posterior part, and which forms the Ligamentvm Ac- ccssorium Posticum. By cutting through the capsular liga- ment, which is in some parts very strong, we shall expose below Poupart's ligament ; also ,that it is the sharp and inner edge of this, "which becomes the principal and ultimate seat of stricture in femoral hernia ; does this practical inference follow that we are not to expect much relief to the stran- gulated intestine, in femoral hernia, by elevating the thigh and relaxing the muscles and fasciae, connected with Pou- part's ligament. Hence, we are not to hold in high expec- tancy, the reduction a femoral hernia, by the taxis ; for we are told by Sir Astley Cooper, that, u in the inguinal hernia. the parts are so connected with muscles, that any relaxation brought upon these, affects the aperture through which the hernia descends: but in the crural hernia, the seat of the stricture is in parts less connected with the action of mus- cles, and general relaxation has but little ei ect upon them" and " the delay of the operation, which I lamented and con- demned, when speaking of inguinal hernia, is to be still more deprecated in the crural ; for death very generally happens- earlier in the latter disease than in the former." And Mr. Lawrence also, notwithstanding he has disagreed with Mr. Hey's notions, of a femoral ligament or crural arch, distinct from the ligament of Poupart, speaks with some emphasis, in reference to the hope, that is to be entertained, for the re- duction of a femoral hernia by the taxis. " Let the practi- tioner remember, that the smallness of the mouth of the sac, and the consequent tightness of the stricture, diminish the chance of effecting a replacement of the rupture, by means of the taxis; and consequently, that when the incarceration is completely formed, he should not waste much time in at* tempts of this description.' " * A large bursa will be seen, in cutting away the tendon of the gluteus maximus ; and generally another, under the ten- dons of the iliaeus ihternus, and psoas magnus. 123 the edge of the acetabulum ; but the bones will not yet fall separate, because the form of the acetabulum is such, that it surrounds part of the head, so as to hold it in its place, in- dependent of the ligaments ; but by pulling a little, the femur will be easily displaced : and now the ligament, which is called by some Ligamentum Teres, by others, Ligamentiwi Truwscuhire, will be seen rising- from the bottom of the ace- tabulum, and passing to the head of the femur. With a very slight jerk, this ligament may be torn ; and then we shall see a fatty substance at the bottom of the acetabulum, which has been called the Apparatus Mucosm, There are some little bands connecte 1 with it, which are called Ligamentulce Adiposce. The femur being removed, we should now compare the size of the acetabulum, with that in the skeleton. We shall see that it is much deepened by the addition of a ring of lig- amentous cartilage, which surrounds its edge. " On the inner part, where the bone is deficient, a distinct portion of liga- ment will be seen, running across the lower part of the ace- tabulum ; this has been called the Ligimentnm Transversals^ while the portion which encircles the edge of the acetabu- luin, is called the .Ligament 'im L'thri Cartll t^'inemn. When we examine the neck of the femur, we may see some small slips of ligament passing from the internal edge of the cap- sular ligament, towards the head of the bone : these slips Jiave been called Retinacula, <-but they are of no importance. TABLE OF THE LIGAMENTS OF THE HIP JOINT. 1. Ligamentum Capsulare. 3 /I , Terr? 5 , , 6. - The ligaments eomseetiag the femur, tibia, and patella to- gether, are very uurrjer.ous ; for though the motions of the knee joint are veyy &ifi?plfe, being merely flexion and exten- sion, still many ligaments are necessary, as the form of the bones is not at all adapted to restrain the joint from being -either too much bent, or too much extended ; but many of the ligaments which are enumerated, are so trifling, that they cannot be considered as in any way adding "to the strength of the joint. The first ligament to be dissected in this joint, as in almost M!! others, is the Capsulare. It is in itself very thin; but it: 124 is strengthened by tendons and ligaments, particularly on f lie fore and back part. There is only one distinct ligament On the inner side of the knee, which from its situation, is called the Ligamentum Lctic.rale Intemum; but on the out- side, two lateral ligaments are described, viz. Long-urn and Breve. There is no difficulty in finding the Longum^ but the Breve is very indistinct, being little more than some scatter- ed fibres, which run from the outer condyle to the tibia. When we examine the posterior part of the joint, we shall find a complicated set of ligaments running between the tibia and femur. They are sometimes described separately ; but they are more generally classed together, under the name of Ligamentum Poplitale, or Ligamentum Posticum Winslowii. The tendon which is between the patella and the tubercle of the tibia, is sometimes described as a liga- ment, and is called Ligamentum PateUce. These ligaments, which are all external to the capsular ligament, may be each considered as important. We should now examine those which appear to be internal to the cap- sular ligament. They are very numerous ; but of the whole, f here are only two, which can be considered of much impor- tance, viz. the two crucial ligaments, but, by a nice disssec- tion, these may be proved to be also external to the capsular ligament. To show the internal ligaments, we should cut through the capsular ligament, beginning at the upper part.* As the cut is carried past the patella, a duplicature, or tucking in of the ligament, will be seen on each side ; the one on the outside, is called the Ligamentum Jllare Exter- num, theother, the Ligamentum Jllare Internum. When we cut through these portions of the capsular ligament, and pull down the patella, we shall see a ligamentous band running towards the fatty matter which lies between the condyles : this is the Ligamentum Mucosum. When this is cut through . or broken, the Anterior Crucial Ligament will be seen ; but to make it more distinct, we should cut through the lateral ligaments, and the ligamentum poplitale, we shall then find, that although all the external ligaments are cut, that the femur and the tibia shall keep their relative position to each other. If we bend the femur to the utmost on the tibia, the Anterior crucial ligament will be distinctly seen : if we extend it fully, then the Posterior will be stretched : and if we twist the femur on the tibia, we shall comprehend why these ligaments are called Crucial. On cutting through * In cutting through the insertion of the muscles, to the patella, we shall open a large bursa, which is often connected with the capsular ligament* 125 these two ligaments,' the femur will fall, separated from the tibia. We have now finished the examination of the liga- ments which unite the femur with the bones of the leg ; but there are still some ligaments on the head of the tibia, which form part of the apparatus of the joint. The Semilunar Cartilages, which, by their peculiar form. deepen the concavity for the lodgement of the condyles, will be seen lying on the upper part of the tibia. If we put the handle of the knife under them, and push it towards the edge of the tibia, the ligament which is called Coronarivm, and which attaches the cartilages to the rim of the tibia, will be (there is only one described for both cartilages.) If we look on the anterior part, between the cartilages, wt< shall see the ligament which is called Transversale ; and lastly, */e may observe, that the extremities of the two car- tilages are attached to the tibia by separate ligaments, each of which is called OMV/v?. The ligaments which are generally enumerated, ?re : (EXTERNALLY.) 1. Ligamentum Capmtare. o. _ -- Patellcc. 3. -- Lot era! e Extcrnvm Lonvvnt 4. J --- , ----- , -- B lute, mum . PopHtale. (INTF.RNALLY.J I. LigatnentiiYn A lare Externum* 9. -- Inter num.. 3. - Cruciate Antic-urn. Posticum. (When the bones are separated,) Coronurinm. 7. _ - Tran.wersale. 8. 9. 10. li. The four Oblique. When we remove the muscles of the leg, we shall find. that the tibia and fibula are bound very strongly together by the Interosseous Ligament; but at the upper and* lower heads. we shall also find regular capsules, and strengthening liga- ments. At the upper head, there are two accessory liga- jnents, one of which is on the fore part, the other behind ; they are called Ligamentum Capititlct FibuJce Jlnticum cr jAgamentum Capitulce Fibulw Posticum; at the Ipwer head. they also receive similar names : but Ve may remark, that ki consequenqe of the inferior ligaments being tfivicted by 126 membrane, and vessels, which pass through the mid- dle of them, some authors have been induced to describe two before, and two behind, thus there would be a Ligamentwti Jlnticum Superius^ and Ligameniicum Jlnticum Inferius, and on the back part, Ligamentum Posticum Superius, and Lig(t~ tn.-en.tum Posticum Inferius. As the ankle joint is nearly a simple hinge joint, thf principal ligaments must be lateral; but, as in this joint, the form of the bones is not very well adapted for checking its motions of flexion and extension, there is a necessity for more ligaments, than those merely for the purpose of lateral motion. The ligamenturn capsulare is very thin in this joint, but it is strengthened by the ligamentous bands which keep the tendons of the' muscles in their proper petitions ; but both these, and the capsular ligament, must be removed, before we can see the proper ligaments. We shall then find, on the ir,side of the joint, a very strong ligament run- ning from the point of the tibia to the astragalus and navicu- lare ; this ligament from its shape, is called Deltoides, or Triangulare. From the tip of the fibula, three portions of ligament will be seen to pass off; one runs perpendicularly from the middle part, to the os calcis, whence it has receiv- ed the name of Perpendiculare, or ^Medium ; anothef runs to the anterior part of the astragalus, and is called Ligamentum inter Fihulam et Astra galum Anlwum; while the third passes from the back of the fibula to the posterior part of the astra- galus, and this is also named, according to its situation and course, { Ligamentum inter Fibvlam et Jlstragalum Posticum, Roth of these ligaments may occasionally be divided into two portions; but they are not named differently on that account. LIGAMENTS BETWEEN THE TIBIA AND FIBULA. (ON THE UPPER PAR.T.) L Ligamentum Capsulare. 2. CapitulcK Fibulae Antintm. 3. ____ __. Postic-wn . \. Interosseum. (AT THE LOWER PART.) 1 . Ligamentwn Aniicum Superius. 2. ' Inferiufi. 3. Posticum Sup 4, * ." 127 LIGAMENTS BETWEEN THE TIBIA, FIBULA. AND BONES OF THE TARSUS. 1. Ligament-urn Capwlare. 2. Deltoid es, or Triangulare. 3. Perpendiculare. 4. Inter Fibulam et Astragalum Aniicuin. 5. Posticum. The ligaments which connect the bones of the foot to- gether, rnay be exposed by removing the tendons of the mus- cles. The ligaments are very numerous, but not of much importance. The names which are given to them, are gen- erally descriptive of the bones between which they run, and the direction their fibres take. Upon the upper part of the foot, there are no ligaments which we would particularly notice. They are called Liga- menta Dorsalia, with the addition of the names of the bones between which they run, and the terms Recta, Obliqua, &c. In the middle of the sole of the foot, the bands are so nu- merous, that we never think of particularizing them; but on the inner and outer part, the ligaments are more distinct. On tiie inside, a strong band of fibres may be traced from the os calcis to the naviculare ; in the upper and middle part of this, a cartilage, somewhat resembling a small patella, will be found, under which is the projecting point of the astraga- lus : this portion of the ligament is called the Trochlea Car- niaginea, the other part being called the Ligamentum Plan- tare MA jus, the MINUS being a more internal portion of the same band. On the outside of the foot, we shall find a very strong ligament passing from the os calcis to'theos cuboides; this is also, by Weitbrecht, divided into two ligaments, viz. Ligamentum inter Os Calcis et Cuboides LONGUM, and Lig : BREVE. It is quite needless to enumerate the small ligaments which bind the metatarsal bones together. The phalanges of the toes are connected together by strong CAPSULAR and LATERAL ligaments, as the joints permit only of FLEXION and EXTENSION. The student will naturally direct his attention to the question of Dislocation and Fracture of the several bones, while the parts are before him. I cannot enter upon the subject, but must refer him to the essays by Mr. A. Cooper, and the system of Operative Surgery by Mr. Charles Bell, where he will find plans illustrative of the several dislocations and fractures. 128 DISSECTION OF THE ARTERIES OF THE LOWER EXTREMITY. As the object of the student, in his first dissection of the arteries, should be, to learn the course of the trunks, and their principal branches, the limb ought to be injected. If the subject be young-, the injection of the arteries of both legs may be made at once from the aorta; but if the body be old, it will be necessary to inject each limb sepa*- ratelv, because, in such a subject, we shall seldom succeed in pushing the injection from the aorta to the extremities of the arteries. But if both limbs be injected from their corres- ponding iliac arteries, the middle sacral artery will be lost. This, however, may also be filled, if the right leg be injected from the aorta, the left iliac having been tied immediately below the point of bifurcation. The other leg may be after- wards injected by putting a pipe into the iliac, below the point where it was tied. As the dissection of the arteries of the leg is very tedious, we should not spend much time in examining the abdominal muscles. We should merely dissect the inguinal canal, and then cut through the muscles below the umbilicus. The viscera should also be removed. The arteries of the pelvis should be dissected before those of the thigh ; because the parts in the pelvis very quickly be- come putrid, and when in this state, if there be any had in the composition forming the injection, the vessels will ap- pear of a black colour. There are very few directions necessary to be given for the dissection of arteries that have been injected. They are to be traced from trunk to branch : and to do this, it is only requisite to raise the cellular membrane, &c. with the for- ceps and scissors. But before the student commences the dissection of the arteries, he ought to consider what are the most important parts of that division of the body, which he is about to exa- mine. This will assist him very much in learning the distri- bution of the arteries, for he will find that the number of branches will very nearly correspond with the number of the more important parts. He will find, for example, that the 129 arteries'which go off from the lower part of the aorta may be divided into three classes : 1. The arteries which pass down to supply the thigh and leg. 2. Those which supply the muscles on the pelvis. 3. The branches which are distributed to the viscera of the pelvis. Those which pass to the thigh and leg will be afterwards subdivided. I shall now proceed to describe the manner in which those that supply the pelvis are to be traced. After the cellular membrane and peritoneum are removed from the Aorta, it will be seen to divide into two great branches, viz. the Common Iliacs. From the point of bifur- cation there is likewise a small vessel passing off', which is called the Sacra Media. The Common Iliac of either side may be very easily expo- sed, for there are seldom any branches given off by it : if there be one, it will probably be that which passes between the vertebra? and the ilium, and is called the ilio lumbalis. But this artery more generally rises from the internal iliac. If we trace the common iliac for about an inch and a half, we shall find it divided into two branches, the External and Internal Iliacs. The external iliac is the vessel which sup- plies the branches of the first class enumerated; but at present we should not trace it farther than to the ligament of Poupart. We may now return to the internal iliac, from which the two next classes of branches are given off. These are par- ticularly difficult to trace ; and were we not to recollect that they formed two distinct classes, it would be difficult to un- derstand them. The trunk, after leaving the common iliac, is almost con- cealed by the great veins ; but these may be cut away, be- cause, in the present dissection, every thing should be re- moved that impedes our view of the arteries. The first branch that is seen, will probably be that which has been already described as coming occasionally from the common iliac, viz. the ilio lumbalis. If the subject be very young, we shall find that the trunk of the internal iliac is continued up on the side of the bladder, and then becomes a ligamen- tous cord, which may be traced towards the umbilicus ; but in the adult, or old subject, we shall find the artery stop rather abruptly before it reaches the bladder. This will be explained by the dissection of the foetus, for there we shall find that the internal iliac is continued to the umbilicus as the hypogastric or umbilical artery, the upper portion of 130 which gradually degenerates into ligament as a person ad- vances in years. In the adult, small branches, which are called vesicates sit- periores, are sent to the fundus of the bladder, from the ter- mination of the artery : they will be seen more distinctly if the bladder be distended. If we hold aside the bladder, we shall probably see certain other branches passing towards its middle, and which are called vesicates medm. These come off generally from the artery, just as it is turning up from the trunk of the internal iliac; but they are very irregular. If we now pull up the bladder, and separate it a little from the rectum, we shall see branches passing towards the prostate and the vesiculse seminales. The origin of these cannot be seen at present, as they generally arise from the pudic. A section of the pelvis, such as has been described at page 80, must be made, before we can trace these branches, or the continued trunk of the iliac. After having made the section, and partially distended the bladder with air, the dissection of the internal iliac may be resumed. The branches of this artery are so irregular in their manner of coming 1 off, that we should trace them for some distance before we attempt to name them. If we should rind one going towards the obturator muscle, it will be the Obturator ; and if we see another large artery passing down towards the outlet of the pelvis, and dividing into two ferajiches, it will probably be the common trunk of the Is- chiatic and Pudic. The large vessel which runs in the angle between the sacrum and the ilium, and appears like the con- tinued trunk of the iliac, will be the Gluteal. But the ves- sels do not always come off in this order. The most irregu- lar is the obturator; for it frequently rises from the external iliac, in union with the epigastric. In dissecting these branches, it will be most Convenient to begin with the obturator. This maybe very quickly traced ; and having finished it, the pudic may be next followed. There is some difficulty in dissecting the first set of arteries which the pudic gives off, for they supply the viscera of the pelvis, and are united with the branches of the inferior me- Fcnteric. In the male, we shall find branches passing to the middle of the bladder (vesicates mediae,) to the rectum (/<#?- morrhoidales,) and to the lower part of the bladder (vesicates imae.) But in the female we shall find, besides these, a very large artery passing to the wterus (the utcrina.) We may now trace the trunk to the space between the sacro ischiatic ligaments. While here, it gives off some muscular branches, but it almost immediately passes again into the pelvis, and iy then distributed to the parts in the perineum, in the manner 131 described at page 78. This description will suffice for only one side of the pelvis ; for in the other the small branches must have been cut across in removing the viscera. As the Ischiatic comes as often from the gluteal as from the pudic, it is difficult to describe the irregular branches which pass from it while it is within the pelvis. But they are generally of little importance, for the artery will be found to pass out of the pelvis, very little diminished in size, to supply the muscles of the hip, in the manner described in the table. In tracing the Ghdeal while yet within the pelvis, we shall find a set of arteries passing off from it to the lateral parts of the sacrum, viz. sacrce laterales. These vessels sometimes arise in one common trunk, but more generally in three or four distinct branches, each of which inosculates with the sacra media, in its course along the middle of the sacrum. Before we can trace the external branches of the gluteal and ischiatic, we must make a superficial dissection of the muscles of the hip. If our object were to keep the arteries after they are dissected, we ought to preserve all the branches which go to these muscles ; but as at present we wish only to acquire a general knowledge of the vessels, we should not attempt to dissect all the smali muscular twigs. We should, therefore, make such a dissection of the mus- cles of the hip as is described in page 102 in doing this, some small arteries passing to the skin, and ramifying upon the fascia of the gluteus medius, will be seen. In separating the gluteus maximus from the gluteus medius, we shall be obliged to cut a large branch, the superjkialis, which passes into the substance of the gluteus maximus. If we then raise the gluteus medius, we shall discover an artery passing under it, and dividing into two branches, which are called Asccn- dens and T-ransversalis. At this stage of the dissection, we shall also see some of the branches of the ischiatic artery forming inosculations with those of the gluteal, and with tl.V branches from the pudic ; but the principal branches of the ischiatic will be afterwards seen passing over the small mus- cles, along with the great nerve, to form inosculations with the branches of the external iliac. We may now return to the dissection of the External Iliac, which has been already traced as far as the edge of thp Poupart ligament. If we hold up the flap of the abdominal muscles, and strip the peritoneum from it, we shall see the first branch, the Epigastric, passing from the trunk towards the rectus muscle ; the next, Circumflexa //', rises about half an inch below the epigastric, and on the iliac edge of the artery ; but the Obturator will be also found coining' from 132 the external iliac, in union with the epigastric, in the propor- tion of one in four to the number of times which it rises from the internal iliac. The main artery, after giving off these branches, passes under the ligament of Poupart : and here, instead of the name of " external iliac," it receives that of Inguinal, or Common Femoral. We shall find the arrangement of the branches which are given off from this artery before it becomes popliteal, to be very simple ; for there is only one series of branches to sup- ply the great muscles, and another to encircle the joints and to form inosculations with the other arteries. The branches which supply the muscles, are either called Perforantes or Jlluscular ; while those which surround the joints are called Circwnflexct) Articular, Recurrent, or AnaMomotic. But, in making this arrangement, we must, at the same time, recol- lect, that the vessel which is passing to supply the parts be- low the knee, is the principal artery in the thigh. The dissection is not to be begun in the same manner as that for the muscles : the skin only is to be carefully remo- ved from the groin, and then some small arteries will be seen passing into the glands of the groin, to the scrotum, to the skin of the penis, arid to the superficial parts of the ab- dominal muscles. Those going to the glands are called In- guinales ; those to the skin of the penis and scrotum, Puden- dce Externce ; and those which pass back to the abdominal muscles, Epigastrica Superficiaiis and Reflexa Ilii. Thesp small vessels are then to be h'eld aside, and the trunk is to be exposed by removing the cellular membrane with the forceps and scissors. The artery will be found lying upon the psoas muscle, with the great vein on its pubic side. The anterior crural nerve lies upon the iliac side of the artery, but not close upon it. There is here much difficult dissection, and the only rule that can be given for conducting it, is to trace the trunk very cautiously with the forceps and scissors, tor large branches will be found passing off from each side of it, and principally from its iliac side : these branches are intimately connected with those of the great vein and the anterior crural nerve, which, however, in this first dissection, may be all removed. The order in which the great branches arise, is so very irregular, that it is absolutely necessary here, as in many other parts of the body, to name the branches according to the parts to which they are going, not by the order of their coming off from the main trunk. At about two inches from the edge of Poupart's ligament, we shall probably find the great artery dividing into two large branches. The one, which passes deep, and rather to the 133 out side, is the vessel which generally gives off the principal branches to the thigh ; it is called the Proper Femoral, or the Profunda. The other is the continued trunk of the Femoral which, after giving off a very few branches, passes into the ham, and there divides into the arteries, for the supply of the parts below the knee. The dissection of the superficial artery should be made first. It may be traced as far .down as the part where it per- forates the tendon of the adductor magnus : in this course there are only some small branches given to the muscles which are close to it ; but while it is perforating the tendon of the triceps, it gives off an artery, which, though not large, is very important in a surgical view, the Anastomoticus Mag- nun. We may now return to the dissection of the branches of the Prof iinda. And here I can only repeat, that to expo.se these branches, we must remove the parts that are closely connected to them, with the forceps and scissors. The two first arteries which we should look for, are the Circwn-- Jiexa Externa and Circumflexa Interna. The first will be ge nerally found going off from the upper and outer part of the profunda, or from the main trunk, immediately before it di- vides ; it then passes under the rectus muscles, towards the outside of the hip : while passing under the rectus, it gene- rally gives off a branch which runs along the vastus externus to the outside of the knee, this is the Ramus Externus De- xcendens Longus. The internal circumflex passes off opposite to this, and immediately dips under the pectinalis, to supply the heads of the deep muscles at the joint, and to inosculate with the branches of the obturator artery. This is more pro- perly the artery of the joint than the external circumflex. The branches of the profunda, which are called Perforantes* and that may now be traced towards the insertions of the tri- ceps, through which they pass to the muscles on the back of the thigh, are, in number, three, four, or five. But before we can see them distinctly, we must make a careful dissec- tion of these muscles, and then many branches will be found going to inosculate with the gluteal and ischiatic arteries, and also with the two circumflex. The dissection of the two ham-string muscles should now be continued down to the knee. Very few arteries will be seen in the superficial dissection ; for the branches are bu- ried in the fat which lies between the muscles ; but if, in looking for the trunk, we dissect deeply the edge of the bi- ceps and semitendinosus, we shall be very apt to cut some of the lateral branches. This may be avoided, by commencing the dissection in the middle of the ham ; for after raising- J M 134 very little cellular membrane, we shall expose the great nerve ; and then, by drawing" it aside, or cutting' it through. we shall, at about half an inch cleeper, find the vein, and im- mediately under it, and close upon the bone, the continued trunk of the femoral artery, which is now called Pnptif.eaf. 1 f we now remove the fat, &c. from .the artery as far up as the point where it perforates the triceps, and as far down as we can, without cutting- through the gastroenemrue muscle, \\r shall discover a very regular series of branches : from the upper part ot the artery, there are several sent back to inos- culate with the perforantes, the principal one of which is Rnmus Profundus Popliteal ; from the lower'* part, two or three arteries, which are called Swales, pass to supply the, gastrocnemius and soleus. The intermediate branches are** called Articular, as they encircle the knee joint : two of thesf pass towards the inner condole, and are thence named Arti- cularis Superior Internet, and Atiicv.iaris Inferior Infema,. The two which arise on the outer edge of the artery, are cal- led Articularis Superior Extema and Arlicularis Jnfe.riorJ-.s~ terna ; but there is still a fifth articular artery, which passes through the ligamentum posticum Winslowii, and supplies the inner part of the joint, and is called, from its being a single branch, JLrticularis Azyga, or JMctfa. We must now separate trie origin of the gastrocnemius from the coridyles, and the origin of the soleus frcm the tibia, in order to show the Popliteal dividing into the Anterior and Posterior Tibial Arteries. We shall see only a small part of the Anterior Tibial, for it almost immediately passes through the interosseus liga- ment; but by raising the fascia which covers the deep layer of muscles, we shall see the Posterior Tibia!, through almost its whole course. This artery generally gives off the Pe.ro* neal, or Fibular Artery, about half an inch, or an inch, be- low the edge of the popliteus muscle. But the fibular is ve- jry irregular; indeed it is described, by many, as rising more frequently from the anterior, than the posterior tibial. While the posterior tibia! is passing the insertion of the popliteal muscle, it gives off a branch, which, passing into the bone, is called the Nutritia Tibiae. The artery may then be traced. under the fascia, to below the inner ankle, without our see- ing any branch of importance ; but here it senxis some branch- es to the heel, which are called Calcanece > and then divides into the Plantaris Externa and Plantaris Internet, which arc to be carefully traced between the muscles in the sole of the foot : in doing this, we shall be obliged to cut many of- the muscles. The plantar arteries will be seen to form mos- 135 euications with those branches of the anterior tibial, which perforate the spaces between the metatarsal bon^s. We should now return to the dissection of the , ..riches of the Fibular Artery. This vessel is not only very irregular in its origin, but also in its size ; for it always depends upon the magnitude of the anterior and posterior tibial arteries. In its course towards the ankle, it gives off small branches t the muscles rising from the fibula, one to the bone itself; and when about four inches from the ankle, it will be found to divide into two branches, which are called Anterior Fibu- lar and Posterior Fibular. The anterior inosculates with the branches from the Tamea-l of the anterior tibial, while the posterior inosculates with the Calcancas of the posterior tibial. We may now make the dissection of the Anterior Tibial. To rind it, we should Hret expose the muscles on the fore part. In doing this, we shall see the recur win passing back upon the knee ; then, by dissecting between the tibialis anti- i-.us and extensor coimnutiis digitorum, we shall discover the mum artery lying close upon the interosseous ligament. It may then be easily traced to the great toe, giving off branch- es in its course, the names of which are descriptive of the parts which they supply. The manner of dissecting the arteries, which has just been described, should be nearly, followed in making a prepara- tion ; but the dissection should be prosecuted in a very dif- ferent manner, in studying the surgical anatomy ; but that I shall not describe until the dissection of the nerves is fin- ished. VEINS OF THE LOWER EXTREMITY. The deep veins of the lower extremity are so easily under- stood, 1 >u-it it is not necessary to make a separate dissection, nor even to inject them, to enable us to trace, them. The Superficial Veuis^ which are the most important, are describ- ed with the cutaneous nerves. With regard to the deep veins, ur cena cowef.es, it is only necessary to say, that they accompany the arteries, and are named according to them. \Ve shall find that many of the arteries have a vena comes a'Ji bide. 136 TABLE OF THE ARTERIES OF THE PELVIS, OF THE THIGH, AND OF THE LEG AND FOOT. ARTERIES OF THE PELVIS. 'UACA COMMUMS, into the ILIACA INTERNA and 1LIACA EX- TERNA. Iliaca Internet, gives off. 1. ILIO LUMBALIS ; to supply the Iliacus Internus and Psoas Magnus. II. SACRJE LATERALES ; three or four in number, to the lateral part of the sacrum. III. UMBILICALIS, or HYPOGASTRICA ; gives off branches to the upper part of the bladder, viz. Vesicales Supe- riores. IV. OBTURATOR; 1. within the pelvis, muscular branch- es to the psoas and obturator interims ; 2. a branch to the back of the pubes ; 3. in the thigh, branches to the obturator externus, pectinalis, and triceps. V. GLUTEA ; passes out of the pelvis over the edge of the pyriformis, and betwixt two of the roots of the great ischiatic nerve, Within the pelvis, 1 . muscular branch- es (sometimes the sacras laterales) ; after it passes out, 2. Ramus Superficial, viz. under the gluteus maximus ; 3. Ramus Ascendens, viz. under the glu- teus medius ; 4. Ramus Transversus, viz. under the gluteus meclius, and forward. VI. ISCHIATICA ; within the pelvis, and in its passage out, branches to the bladder, rectum, and neighboring muscles ; on the back of the pelvis, to the glutei, to the great nerve, to the lesser muscles of the thigh bone, in many profuse branches. VII. Pubic A INTERNA; before it passes out of the pelvis, it gives off, 1. Ha}morrhoidales Mediae; 2 Vesicales Ima3 ; while between the ligaments, 3. to the gemini, ob- turator, and pyriformis muscles ; on entering the pel- vis again, 4. Ha3morrhoidales Externa3: in the perine- um, 5. Superficial Perinei ; 6. Transversalis Perin- ei ; then we find the three important arteries continued from the trunk, (Jlrteria Communis Penis) 1. Artery of the Bulb, 2. Arteria Profunda Propria, 3. Arteria Superficialis, Dorsalis Penis, 137 ARTERIES OF THE THIGH. ILIACA EXTERNA. (within the abdomen.) I. IRREGULAR BRANCHES TO THE MUSCLES. II. ARTERIA EPIGASTRICA : 1. to the cord and crernasU-r muscle ; 2. towards the back of the os pubis ; 3. prin- cipal branch ascending upon the rectus ; 4. sometimes the obturator. HI. ARTERIA CIRCUMFLEXA ILLI; to the iliacus interims, to the abdominal muscles, anastomosing with the ilio lumbalis, and often a branch to the spermatic cord. FEMORAL ARTERY. 1. KAMI IiNGurNALEs; 1. to the glands, fat, and integu- ments : -2. Ramus Major, sometimes called Reflexa Ilii ; 3. Epigastrica Superficialis, but this is very irregular. IE. ARTERIJE PTTDENDJE, viz. 1. pudenda superior, 2. pu- denda media, 3. pudenda inferior. HI. CIRCUMFLEXA EXTERNA ; (sometimes from the femo- ral, but most commonly from the profunda ;) 1. mus- cular branches ; 2. transverse branch to the muscles, 3. the proper branch to the joint communicating with the circumflexa interim ; 4. Ramus Externus De- scendens, passing between the vastus externus and rectus, arid inosculating with the articular arteries of the knee. IV. CIRCUMFLEXA INTERN A : (often from the profunda ;) 1. branches to the triceps ; 2. branches to inosculate with the obturator ; 3. branches to the capsule of the joint. V. PROFUNDA ; 1. irregular branches; 2. great descending internal branch 1 . ramus perforans primus, 2. ramus perforans secundus, 3. ramus perforans tertius, and sometimes, 4. ramus perforans quartus. SUPERFICIAL FEMORAL ARTERY. I 1 . IRREGULAR BRANCHES TO THE MUSCLES WHICH IT PAS- SES. It. RAMUS ANASTOMOTICUS MAGNUS. This is the first considerable branch which the femoral artery gives *ff, viz. while concealed in the tendon of t 138 POPLITEAL ARTERY. (Being that part of the trunk which lies in the cavity freinnu the knee joint.) I. RAMUS PROFUNDUS POPLITE^ : to the ham-string mus- cles, &c. II. ARTERIA ARTICULARIS SUPERIOR EXTERNA; 1. Ramus Profundus ; 2. Superficialis. III. ARTERIA ARTICULARIS SUPERIOR INTERNA ; 1. Ramus Profundus ; 2. Superficialis. IV. ARTERIA ARTICULARIS MEDIA. A branch enters under the ligament of Winslo w. V. ARTERIA ARTICULARIS INFERIOR EXTERNA; 1. to the muscles ; 2. deep, and passing above the head of the fibula. VI. ARTERIA ARTICULARIS INFERIOR INTERNA ; chiefly su- perficial, and beautifully encircling the head of the ti- bia. VII. BRANCHES TO THE GASTROCNEMII MUSCLES, viz. THJ. SURALES. GREAT DIVISION of the POPLITEAL ARTERY into the ANTERIOR TIBIAL ARTERY and the POSTE- RIOR TIBIAL ARTERY. ANTERIOR TIBIAL ARTERY. 'Before passing betwixt the bones 1 . A small ascending branch which may be called Articularis Tibialis. &s it escapes from the interosseous ligament 2. Recurrens Tibialis. Upon the ligament 3. Successive muscular branches- 4, Malleolaris Interna. 5. Malleolaris Externa. .Before the ankle 6. Tarsea. 7. interossea?. On the foot 8. Metatarsea. Dorsales Digitorum. 9. Dor- salis Halucis. 10. RAMUS PROFUNDUS ANASTOMOTI- cus. POSTERIOR TIBIAL ARTERY. I. MUSCULAR BRANCHES, AND THE NUTRITIA TIBIJE. II. FIBULAR ARTERY; 1. numerons muscular branches posterior fibular artery ; 3. anterior fibular artery. (near the ankle.) III. CALCANEJE. IV. PLANT ARIS EXTERNA ; 1 . Transversus Anastomoticus , 2. Profundse ; 3. Digitales, quartse ; 4. Interossea Profundse; 5. ANASTOMOTICA, viz. with the anterior tibial artery. 139 PLANTARIS INTERN A ; 1. branches to the flexor tendons, and to the abductor and flexor pollicis ; 2. ProfundsE;, viz. interior, middle, exterior ; 3. Ramus Externus. DISSECTION NER FES OF THE THIGH AND LEG, The arrangement of the nervous system of the lower ex- tremity, is very simple ; for there are only a few branches which pass to the skin, and three great nerves which supply the muscles. The dissection of these nerves would be very easy, were they all below the fascia ; but as the cutaneous nerves are superficial to it, it is very difficult to show them and the deep nerves at the same time. We should, therefore, dissect the cutaneous nerves first ; and after having examined them, we may cut them through, or hold them aside, that we may make the dissection of the deep branches.* If we tear the peritoneum from the lower part of the mus- cles of the abdomen, and of the loins, we shall see several small nerves passing across the iliac muscles towards the thigh ; these will be afterwards found to be the cutaneous nerves.f One of these may be seen running from the first lumbar, across the psoas magnus and the quadratus lumbo- rum, to the posterior part of the spine of the ilium. From this it may be traced, for some way, in a canal between the * It would, perhaps, have been better to have described the nerves of the viscera before those of the lower extremity, as it will be necessary to remove them, before the origin of se- veral of the nerves which pass to the thigh, can be shown. But as this would have broken in upon the arrangement of the dissections of the thigh, the present plan has been follow- ed; the nerves of the viscera will be described with those of the thorax ; if the student wishes to dissect them first, he should refer to that part of the work. t It is difficult to say what names ought to be given to the cutaneous nerves, because there are very few authors who 140 transversalis and spine of the ilium ; it then pierces the tran< versalis, and while lying between it and the internal oblique, divides into two branches one of which supplies the abdom- inal muscles and integuments ; the other may be traced be- tween the two muscles, and along Poupart's ligament, as far as the external abdominal ring ; it then perforates the apone- urosis of the external oblique, and is lost upon the skin and scrotum in the male, and upon the labia in the female. Another nerve may also be traced from the first lurrrbar, across the psoas and iliacus internus ; it pierces the transyer- salis and internal oblique, and then it gives off several branch- es ; the principal one is that which passes along the crural arch to the upper part of the scrotum. We may now look to the second lumbar nerve, and from it we may generally T race a nerve which pierces the psoas, and crosses the ilia- cus internus, to pass out of the pelvis, between the two ante- rior spinous processes of the ilium : it will then be found un- der the fascia lata ; here it a.ppears a little enlarged, and im- mediately divides into two branches, one of which passes to the skin, but the other goes directly downwards for a short distance before it pierces the fascia; it is then distributed to the skin on the outer part of the thigh, nearly as far down as the knee. But the most important branch of all these cuta- neous nerves, is that which rises from the first lumbar, and while it is passing through the substance of the psoas, re- ceives a branch from the second lumbar. This nerve passes along the fore part of the psoas, and when near the crural arch, divides into two branches, the largest of which follows the course of the spermatic cord, and is distributed on th..* scrotum and coats of the testicle; the other branch passes under the great vessels, and after giving twigs to the ingui- nal glands, sends a number of branches, through the fascia, to the skin on the fore part and middle of the thigh. Besides the branches which have just been enumerated, three or four nerves will be seen coming through the fascia, h> be distributed upon the skin on the fore part of the thigh. These will be afterwards found to arise from the anterior cruraL We should now trace the cutaneous nerves on the hip. In raising the skin from the gluteus maximus, we shall discover upon its upper part, a set of nerves which arise from the lum- bar ; on the lower part of the muscle we shall find another use the same terms ; but the most common plan is to give them such names as are descriptive of their situation thus we have the terms External Cutaneous, Internal Cutaneou^ Middle Cutanevus, External Spermatic, and External Pudu\ 141 set, which arise from the sacro-ischiatic, and the most im- portant brandies of which, pass to the skin of the perineum and anus. On removing- the skin from the ham-string mus- < les, several cutaneous branches will be seen passing down on the outer and inner edges of the thigh. Those which are on the inside, (called the Posterior Internal) may be traced from the sacro-ischiatic, as it passes over the quadratus fe- inoris ; and those on the outside, (the Posterior External ,} rise from the great nerve, after it has emerged from the glu- tens maximus. If we now continue the dissection along the .superficial part of the leg, we shall discover two branches, which unite nearly opposite to the middle of the gastrocnemius ; one of these, will be found to arise from the tibial portion of the .sacro-ischiatic the other from tho peroneal division ; they may be traced to the outer part of the tendo Achiliis, where they unite with nerves from the anterior part of the foot, whence the nerve formed by the union, has received the name of communicans tibialis. To discover the origin of the cutaneous nerves which sup- ply the fore part of the leg, it will be necessary to open the .sheath of the femoral artery, immediately before it pierces the adductor magrms; there we shall seethe nerve which is called saphenus longus. This "may be traced under the fas- cia, to the inside of the knee ; here it joins the saphena vein, which it accompanies to the inner ankle. In its course, it forms connections with the cutaneous nerves on the back of the leg, and with those of the deeper nerves, which shall be described presently. In making the dissection of the cutaneous nerves, we should, at the same time* attend to the distribution of the superficial veins, which may be seen, though uninjected. All the cutaneous veins of the leg are described as forming only two trunks, viz. Saphena Jttajor, or Interna, and Saphe- na Minor, or Externa. The saphena major may be traced from a plexus of veins on the inside and fore part of the foot ; from this it passes over the inner ankle, up to the inside of the knee ; it then passes upon the fascia lata to within a hand's breadth of Pou- part's ligament ; here it perforates the fascia, and unites with the great femoral vein. We shall sometimes find it divided into two branches above the knee; but these generally join, before the vein perforates the fascia. The saphena minor rises from the plexus on the back and outer part of the foot, from which it may be traced, alontr the middle of the gastrocnemius, to the ham ; here it termi- $ates, by uniting with the popliteal vein. 142 Some of the superficial lymphatics may be seen in tins *tage of the dissection, but to an inexperienced eye, it will be very difficult to discover them. The manner of injecting them, will be described in a separate article ; at present, I shall only notice, that these lymphatics are immediately un- der the true skin ; that they are more superficial than the veins and nerves; that they run in straight lines, and are only partially seen, or seem to be abruptly broken off, by tin? intervening pellicles of fat. They appear very large and varicose when distended, especially in the course of the sa- phena vein; and they are more numerous upon the middle part of the thigh, than upon the outer part. In colour and appearance, when in their natural state, and collapsed, they resemble loose muscular fibies, being flat reddish lines; be- ing pellucid only when distended with air. When they are blown up, or injected with mercury, they take a very pecu- liar appearance, for they swell only betwixt their valves. The lymphatics of the thigh, pass into the glands at the groin, but we must particularly notice that there are three sets of glands here the first receive the lymphatics from the super- ficial part of the thigh, the second receive the lymphatics of the skin of the penis and scrotum, and perineum, while a deeper set are formed by the lymphatics which accompany the great arteries of the legs When the glands are injected, secondary lymphatics may be traced from them into another set of glands. The lymph is then carried from these, by a third set of vessels, to glands which have a direct communication with the thoracic duct. The superficial lymphatics on the back of the leg, may be traced into a gland in the ham. Previous to the dissection of the deep serves of the thigh, a section of the pelvis should be made, according to the second method described at page 72. As it is supposed that all the nerves of the viscera, and the cutaneous nerves of the thigh, have been already traced, we have now to attend only to the origins of the Anterior Cru- iv//, Obturator, and Ischiatic Nerves. The fibres of the psoas muscle must be freely cut, so that we may e'xpose the plexus of nerves which gives origin to the Anterior Crural. This plexus is generally formed by the second, third, and fourth lumbar, and the first sacral. The anterior crural may be traced in the angle between the psoas and iliacus, as far as the edge of Poupart's liga- ment; but before we trace it farther, we should attend to the -Obturator, which is seen passing across the pelvis, to- wards the thyroid hole. If we trace this nerve back towards the loins, we shall find it in close connection with the ante- 113 rior crural nerve; for it also arises from a plexus, Which is formed by the third and fourth lumbar nerves, and sometimes by a twig from the second. By a very little dissection, we may now expose the great plexus of the Sacra-sciatic Nerve. When this is traced back- ward, it will be found to be formed by the fourth and fifth lumbar, arid by the first, second, and third sacral nerves.* The three great nerves, viz. Anterior Crural, Obturator* and Sacro-uchiatic, may now be traced to their final distribu- tion. The Anterior Crural, having passed under Poupart's liga- ment, immediately splits into a great number of branches, many of which may be traced into the muscles at the upper part of the thigh ; while others, which have been already de- scribed, go to the skin. Of the muscular branches there are only two which it is of much importance to trace, arid both of these run parallel to the femoral artery. The most external one does not run close upon the artery, but inclines towards the vastus inter- mis, upon which it is distributed; while the internal, (which is called the saphenus longus,) passes almost in the proper sheath, until thn artery perforates the triceps. The nerve may then be traced to the inside of the knee, to become the cutaneous nerve, which has been already seen going to the inner ankle, along with the saphena vein. To show the branches of the Obturator, we must dissect between the heads of the triceps : here we shall find many tvvigs, but of these, the only important ones are one or two which run along the inside of the thigh, to unite with the sa- phenus lougus.- While the Sacro Isrhiatic Nerve is in the form of a plexus in the pelvis, it gives off several branches, the principal of which is the P-mlic : indeed, this may be considered a separate nerve, as it arises from the third, fourth, and fifth sacral nerves. It may be traced by the side of the tuber ischii, along with the arteries, to the muscles of the perineum, and to the penis. In the female, it is distributed on the vagina and clitoris. The trunk of the ischiatic, after giving off the pudic, passes to the outer part of the pelvis ; it generally lies be- tween the pyriformis and gemini muscles, but it is not un- * These lumbar and sacral nerves may be more easily counted by looking into the section of the spinal canal. When the nervee of both sides are preserved, and pulled out from the spinal canal, there is the appearance produced, which has been called Cauda Equina. 144 usual to find the pyriformis perforated by the nerve ; some- times, indeed, the nerve is divided, by the tendon, into two branches, which, however, soon again unite. While the nerve lies here, it gives several small twigs to the muscles and to the skin. The two great gluteal muscles should now be raised, by which we shall expose the nerve where it passes betwixt the tuberosity of the ischium and great trochanter ; the two ham-string muscles must then be dissected to show the course of the nerve between them. About the middle of the thigh, the sciatic nerve will be found to divide into two great branches, the Tibial and Fi- bular. The trunk, however, will very often appear to go quite into the ham, without dividing ; but still we shall find that it may be very easily split, for some way up, into two portions. The Tibial should be traced first. The first branch of importance, is that which has been already seen in the dis- section of the cutaneous nerves (JVcrvus Communicans Ti- bialis.) After having given off this branch, the trunk passes through the popliteal space, giving off small branches to the back of the joint, and to the muscles. The internal heads of the gastrocnemius and sole us should now be divided, so that we may exhibit the nerve in its course under the fascia which covers the deep muscles. As it pas- ses to the ankle, it gives oifseveral branches, the principal one of which passes between the bones to supply the muscles on the fore and upper part of the interosseous ligament. At the internal ankle, the trunk will be found lying close upon the posterior tibial artery ; and whilg here, it gives off a cui taneous branch to the inside of the foot. The Internal Plantar, which is the largest, after giving off several branches to the muscles, is finally distributed to the great toe, second, third, and one side of the fourth toe. The External supplies its corresponding muscles, forms a connection with the internal plantar,and then supplies the little toe, and one side of the fourth toe. The Fibular Division of the great sciatic may now be traced. Before it passes round the head of the fibula, it gives off the cutaneous branch which has been described as con- nected with the communicans tibialis. After tracing the trunk over the fibula, it will be found lying very deep be- tweeen the muscles, where it immediately divides into two nerves. The most superficial should be traced first : it gen- erally sends one branch into the muscles, and then, passing under the head of the peroneus longus, may be traced under the aponeurois, to the skin on the fore part of the foot, where it unites, on the outer part, with the communicans tibialis, 145 and, on the inner part, \vith the internal plantar branches Those branches on the fore part of the ibot, are sometimes called Metatarml Nerves. We may now return to the dis- section of the deep nerve, which is sometimes called the An- terior Tibial -Nerve, as it accompanies the artery. It runt?, almost close upon the interosseous ligament, between the deep muscles, as far as the ankle, there it divides into two branches, which are called Ramus -Dorsalis PecHs Profwrxhis, and Superficial. The profundus may be traced, under the extensor brevis, to the outside of the tarsus. The superfi- cialis, though so called, runs deep under the tendons, u;xi at last comes out betwixt the great and second tee. SURGICAL DISSECTION OF THE LOWER EXTREMITY. I SHALL now r endeavor so to describe the manner of ma- king the dissection, as to enable the student to understand the principal points of the anatomy by which .he is to be gui- ded in the treatment of many of the most important cases in surgery. The arteries should not be injected nor should the abdo- men be opened : and if we wish to examine the parts connect- ed with the subject of hernia, we should not make the deep dissection, until we have seen the relative situations of the #reat arteries ; because the most important questions which may be understood from the views of the natural state of thr parts, relate to the different operations which it may be ne- cessary to perform for the various kinds of aneurism. But here 1 must beg the student to understand, that he will be sadly disappointed if he expects to see the parts as distinctly in an operation as he will now see them on dissection. He should, therefore, at the time he is investigating the anato- my, not only read the histories of all the cases and operations? which have been published, but also those works in whicf; the principles that are to guide us in determining on the mode of operating, are discussed. If he does this, he will then be able to assign the great improvements that of lalfr $ r -urs have taken place, to their proper source, 146 With the hope that the student will attend to the patholo- gy of aneurism, I ghall now confine myself to such points as maybe understood by the examination of the parts in the (lead body. The aorta has been tied for an aneurism of the inguinal ar- tery ; but the detail of the operation, and of the cases which were adduced in support of the principle upon which it was done, are sufficient to deter us from ever repeating the exper- iment. The common iliac has been twice tied ; and though the operations were unsuccessful, still the circumstances, in the one which I witnessed, were so far favorable, that we may expect, in certain cases, to tie this vessel with success : but I shall not give a separate description of the manner of dissecting for it, because it may be easily found by making a little variation in the operation for tying the internal iliac. But the most important operation, because .it is the more common, is that upon the external iliac. I ghall, therefore, particularly describe the manner in which this artery may be most easily found, and safely tied, for an aneurism at the groin. I shall suppose that the dissection is made on the liv- ing body ; and, in the description of it, I shall nearly follow that given by Mr. C. Bell, in the Illustrations of the Great Operations of Surgery. " The object of this operation is, to tie the external iliac artery so high, that the wound shall not interfere with the tumor of the aneurism, rioropen the coagulated blood to the influence of the air, nor excite inflammation in the sac, by its contiguity. The wound must not be a penetrating wound, that is, there must be no breach of the investing membrane of the abdomen ; or the patient's clanger will be increased a hundred fold. " Incision. Having ascertained the middle point betwixt the superior spinous process of the os ilii and the KymphisiB pubis, you feel there the pulsation of the artery. Next feel the spermatic cord, and trace it backwards into the abdcmr- iial ring ; and mark where it disappears. You have now got two points to direct your incision ; make another, by drawing a line from the superior spinous process of the os ilii to the umbilicus ; mark a point npon this line, two fingers' breadth from the process. Begin the incision opposite th> outer margin of the "abdominal ring ; carry it over the point where you felt the artery beating, in a direction outward and upward, and let it terminate at the point you have marked at two fingers' breadth from th spinous process of the os ilii measured in a direction towards the umbilicus. " Second Incision* Having exposed the aponeurosie or tendon of the external oblique muscle, and observed the di 147 rection of its fibres pass the directory into the ring, and into the spermatic passage ; taking care that the instrument is directly close under the tendon, and, consequently, external to the cord: slit up the tendon in the direction of its fibres. " Tke Cord. The spermatic cord is now exposed. With the blunt hook, and the handle of the knife, the cord is to be raised and pressed upward and inward. In doing this, you will necessarily raise the lower edge of the obliquus internns muscle. If the patient be fat, or the aneurism prominent and high, the wound, in this state, will be too confined ; and it will be necessary first to pass the directory, and then the point of the finger under the edge of the muscles, and to di- vide them in a direction upwards. The condensed cellular membrane, or fascia, which is on the lower surface of the transversalis, will generally yield to the finger. " There will be found a soft mass just within the Poupart ligament ; it may be mistaken for a vessel ; the more espe- . cialiy, as the pulsation may be felt on pressing it. It is a lymphatic gland. This gland is to be left in its place. Above this, there is a soft, fatty substance, which is to be put aside with the finger and the handle of the knife ; and now> upon putting in the finger, the artery will be distinctly felt. " The space where you feel the artery, is thus defined : 1. Balow, towards the thigh, there is the Pourpart ligament, and the internal inguinal gland. 2. On the inside, towards the pubes, you have the epigastric artery. 3. Above, and towards the ilium, there is the edge of the oblique and trans- versalis muscle. 4. And above, and towards the rectus, you have the spermatic cord. " You should now push up the spermatic cord and cellu- lar membrane,* and you place an assistant's finger there, to guard the peritoneum ; you have the epigastric artery on the inside, still involved in its cellular membrane : you may now expose the artery. " Feeling the artery full, and pulsating und^r your finger, you think it bare, when a little consideration should remind * To me, it appears that there are good reasons for push- ing up the spermatic cord. First, you get much easier at I he artery. Secondly, you have the spermatic cord betwixr, you and the peritoneum. Thirdly, if you incline, you may, in this direction, push the peritoneum very high, and expose the external iliac artery at its highest point ; whereas, if you go above the spermatic cord, and keep it in its place, you must be entangled in the reflection of the vast deferens, and you will make the peritoneum thin as a cobweb, by separa- ting the cellular tissue of the wrdfrom it. 118 you that it is" not.* It is still covered with its sheath, and ill aments of the fascia strengthen that sheath : and here 1 must again observe, that the safest way is, to scratch the sheath, directly over the centre of the artery; to cut at the side of the artery is dangerous. The vein lies close by the inside of the artery, and, in some measure, below it. The vein is on the inside, the anterior crural nerve on the outside. f Therefore, I advise you to scratch until you can pass your probe or blunt hook through the sheath and ligament ous fibres which directly cover the artery. " When you have exposed the proper coat of the artery, make the assistant raise the thigh as much as the circum- stances of the tumor will admit ; then you will be able to a - rasp the artery betwixt the thumb and the fore finger ; you will find it so loose, that you will experience no difficulty in ins?ing the needle under it. It is struggling to thrust the blunt needle through the sheath and fibres of the fascia, and neo'lecting to raise the limb, that makes this part of the ope- u tedious. One firm ligature of four threads, waxed and oiled, will ho sufficient ; it is not necessary to tie the artery twice, nor, consequently, to cut it across. "J The operation of tying the external iliac artery, has been very successful, when performed for spontaneous aneurism of the inguinal artery, but not for the aneurism that rises in- consequence of a wound of this vessel. It is, therefore, of the greatest importance to attend to the distinction of these * Mr. Albemarle says, " The pulsation of the artery made it clearly distinguishable from the conspicuous parts, but 1 could not get my finger round it with the facility which I ex- pected" " After ineffectual trials to pass my finger beneath the artery, I was obliged to make a slight incision on either side of it, in the same manner as is necessary when it is ta- ken up in the thigh, where the fascia, which binds it down in its' situation is strong." This double incision is not necessa- ry in either of these cases ; and, I apprehend, very danger- ous in the present instance. f The external iliac vein is close to the inside of the arte- ry. The anterior crural nerve is quite removed from the ar- tery. J Mr. John Bell and Mr. Abernethy, and Mr. Maunoir of Geneva, have been advocates for tying the artery twice, and cutting it betwixt the ligatures. It is a practice which may have advantages ; but the idea that they thereby made thr artery as secure as when tied in amputation, was undoubted \y a great mistake. 149 v.;is'-s. This difference was first particularly explained b) Mr. Charles Boll ; for he showed, that, in th'e case of spon- taneous aneurism, the tying of the artery at a certain dis- tance above the aneurism, would generally be successful ; but that the artery must be tied above and below an aneurism- which has arisen in consequence of a wound. As it is not possible to guess where it may be necessary to perform such an operation, we ought to make ourselves acquainted with all the connections of the artery through its whole course, that we may feel confident when called .upon to take it up, at any point, in the living body. The operation of tying the internal iliac artery, has been performed for aneurism of the gluteal artery, with success. The operation was thus described to me by Dr. Stevens : " I made an incision, about five inches in length, on the lower and lateral part of the left side of the abdomen, nearly half an inch to the outside of the epigastric artery, and par- allel to that vessel. After dividing the skin and the three abdominal muscles, successively, I separated the peritoneum from its connection with the iliacus interims and psoas, and then pushed it up towards the division of the common iliac. Here I was able to insinuate my finger behind the internal iliac, and then to compress it. between my finger and thumb ; I then passed a ligature befow the artery, with a blunt nee- dle, and tied it with a single ligature, about half an inch from its origin." The pulsation in the aneurism immediate- ly stopped, and the patient, got well. Though it is difficult to suppose that such a case will oc- cur, as would make it necessary to tie the gluteal or ischiatic arteries, where the parts surrounding them are, at the same time, in a natural state, still I shall describe the manner in which these arteries may be found, where the pressure of the blood has not destroyed the tissue of the muscles. For the Gluteal. The body should be laid flat on the bel- ly, and the foot should be turned inwards. The incision should begin at two fingers' breadth below the posterior epiaous process of the ilium, and be continued towards the upper part of the trochanter ;-.iajor. The fibres of the glute- us raaximus and medius, are then to ba divided, to the low- er edge of the ilium, and there, at the notch, and immediate* ly above the pyriforinis muscle, the artery will be found. In making these incisions, we must necessarily cut through se- veral very large arteries. The incision for the Itchiatic artery is to be begun at the side of the sacrum, at about three inches from the posterior spinous process of the ilium, and is to be carried in the length *ft&e fibres of the gkite.us maximum to the eutskle tftJie 150 tuberosity of the ischium ; by pushing in the finger, we shatf feel the external sacro sciatic ligament, along which, and immediately under the margin of the pyriformis, the artery passes. The great nerve is about an inch to the iliac side of the artery. We may now proceed to the consideration of the most, common operation which is performed on the arteries of the lower extremity, the ligature of the superficial femoral ar- f ery, for popliteal aneurism. As this operation, in nine out of ten cases, is done upon parts which are in their natural state, we can now form very nearly an accurate idea of the steps of an operation, which is little more than a simple dissection, made upon the living body. The limb should be laid rather on the side ; a point is then to be marked on the groin, equidistant from the symphysis of the pubes, and the superior spinous process of the ilium. Here the artery will be felt. A cord may be fixed at that point, and stretched to the patella ; an assistant should then stretch another cord bet ween the superior spinous process of the ilium and the inner condyle of the femur. The centre of the incision should be about an inch above the point where these lines cross ; it should be made about three inches long: not in the line of the fibres of the sartorius, but rather across them. The skin is to be divided in the first incision ; and in the second, the thin superficial fascia, which should be cut to the full extent of the incision through the skin. As the cut is made in a line across the sartorius, there will be little difficulty in recognizing this muscle. (And here I may re* mark, that none except those that have witnessed the exhibi- tion, can imagine the difficulties which have ensued, in con- sequence of the edge of the triceps having been mistaken for the sartorius.) The lower edge of the sartorius is now to be raised, this will expose the fascia which passes from the triceps to the vast us internus ; a little perforation is then to be made into the fascia, and a directory is to be passed under it, so that it may be slit up. The sheath which surrounds the artery, vein and nerve, will now be seen, and when this is opened, it will be easy to pass a blunt needle under the ves- sols. The saphena nerve is so far removed from the artery, that it can easily be avoided ; if it be tied, the patient will, as long as he Jives, be a reproach to the surgeon, for he will complain of a pain, so distinctly in the course of the nerve, that there never will be a doubt as to whom he owes it. The internal saphena vein is quite out of the line of the incision 151 lias been recommended ; but as it is irregular in if ^ Bourse, its situation should be marked, previous to com- mencing the operation, by compressing it high up. (Thr anatomy of popliteal aneurism will be described when we come to the dissection of the ham.) We may now open the abdomen, and examine the rela- tive position of the parts connected with the arteries which we have tied. The internal iliac vein and the ureter will be looked to with interest, in considering the operation of tying the internal illiac artery. * After having fully investigated the subject of the operation for aneurism, in all its bearings, we should make a superfi- cial dissection of the fascia of the thigh, preserving the veins, nerves, and glands. The lymphatics, of course, cannot be seen. The first thing we should attend to, is the anatomy of the glands. As the lymphatics pass from several sources into the glands, we may now understand that there may be many different causes for bubo. If there be a deep swelling in the groin, it may be in consequence of some irritation on the in- ternal parts of the limb, as after compound fracture, disea- sed joint or bone. If the swelling be more superficial, it may arise from irritation of the superficial lymphatics in some part of their course, as that produced by a. blister on the knee, or by a sore on the toe. If the tumour be high up in the groin, it will probably be from irritation on some part of the penis or scrotum. But there is another cause of bubo, which on account of the difficulty of tracing the lymphatics, is not generally known, viz. irritation about the anus, as piles, &,. Though buboes have been mistaken for hernia, and what is more serious, hernia has been mistaken for bubo, I hope it. is not now necessary to say any thing on the manner of dis- tinguishing the two diseases. When we recollect the origin of the small nerves which we now see on the thigh and hip, we cannot wonder, that painful sensations in the thighs, should be occasionally re- lieved by such purges as will completely empty the colon and rectum. By now making a very little dissection over the outer edge ofthe psoas muscle, we shall expose the course which the lumbar abscess generally takes ; and when we recollect ' the relations ofthe fascia iliaca, we shall understand why this abscess seldom or never points at the same part that femoral hernia protrudes. The lumbar abscess appears in the groin, commonly upon the outside of the femoral artery, under the stronger part of 152 the fascia, and near the os ilium. When the tumor form* slowly and regularly, the fascia can be plainly felt ; but when it is far advanced, the fascia generally gives way. This ab- scess, however, does not always point thus regularly, but is .sometimes more extensively diffused in the groin, even sur- rounding and including the femoral vessels ; or it runs so deeply among the muscles, that the lancet or trochar cannot reach it with safety. In the dead body, upon laying* open the abscess in the thigh, and freeing it of matter, a new dis- charge will be seen to come from within the belly. Upon following this sinus, it will be found to run up, behind the psoas muscle, upon the vertebrae of the loins, which are often carious. In some instances, the abscess continues its course by the sacrum and side of the rectum, and points by the side of the anus; and it has even made its way into the thorax; With this view of the fascia before us, we at once compre- hend the importance of making free incisions, when matter is collected below it. W T e may now make the dissection of the deep parts of the thigh. When the fascia is cut through below the groin, we shall see the vessels connected together by a separate fascia, which is called the sheath ; the great vein is here on the in- side of the artery, but it turns more and more under the arte- ry as it descends to pass through the triceps muscle. The vein is very strong in its coats ; and perhaps, in an opera- tion, it might be mistaken for the artery, if the surgeon were to judge by the feeling betwixt his fingers, which in many cases is a good criterion. The femoral artery, as it descends from the groin, gets be- twixt the tendinous insertions of the triceps and the origin of the vastus interims muscles. Betwixt these two muscles, there is such an interlacing of tendinous filaments, that they form the bottom of a deep groove, in which the artery runs ; and here it is covered by that fascia which has in part been out. to expose the artery, in performing the operation for aneurism. We may now trace the artery through the sheath formed by the tendon of the adductor magnus ; and we should par- ticularly notice a branch which is given off here, for though it is small, it is of considerable importance in the operation of amputation of a diseased knee; for as this is the part, at wjiich the great artery will be generally cut, there is some chance of this branch being overlooked in the securing of t he vessels : and when this has happened, a dangerous hse- morrhage has been the consequence. The easiest \vay oi* -luuuiging 1 this small vessel, will be, to pull the main artery 153 ouiot* its sheath, so 'that we may apply a ligature above thf the Presse Artere ; by the aid of which, the artery was Dot puckered, as it must always be by the circular ligature, 156 but it was"flattened by the little plate which forms the end of the instrument. I took care to moderate still more the pres- sure upon the artery, by putting under the plate a small piece of agaric, secured by a thread. After the superior and inferior ligatures were applied, the tourniquet was relaxed r the blood did not flow from the opening in the artery. T then proceeded to the application of the dressing. The liga- tures d'attente, being each enveloped in a piece of fine linen, were placed at the angles of the wound ; the wound was fil- led lightly with charpie, so as to avoid the slightest pressure, and at the same time to preserve the vertical position of thf k presse arlere" &c. We may now remove the skin from the parts below the knee, leaving the veins and small nerves upon it. In dissecting the veins, we should consider the. diseases which they are most liable to, particularly their varicose state. In the dissecting room we shall find many opportu- nities of examining varicose veins, and proving that the com- mon ideas upon this disease are erroneous ; for we shall find that the valves are not destroyed, but that the coats of the veins are thickened, so as to prevent the valves from doing 1 their office. I may here remark, that a practice, which, a priori, would not be considered good, will be of great service in relieving the varicose state of the veins, and the ulcers that are a consequence of it, that of applying a spring compress ver the trunk of the varicose vein. In dissecting these veins, we should pay particular atten- tion to their relation to the fascite, that we may not be foil- ed in finding them at once, when we wish to cut them across* We should now consider what will be the best method of dissecting for the anterior and posterior tibial arteries, if it should be necessary to tie them. If the anterior tibial is to be tied high in the leg, the inci- sion through the fascia w^hich covers the muscles, must be very free, because the artery lies very deep. By then dis- secting between the tiabilis anticus and the extensor eommu- nis digitorum, the artery will be found lying upon the inte- rosseous ligament, accompanied by the vena> comites, and almost covered by the nerve. The artery, about four inches from the ankle, will be found between the tibialis anticus and extensor longus pollicis ; and on the interior part of th* foot, between the extensor communis digitorum and the ex- tensor longus pollicis. The posterior tibial may be found about the middle of the leg, by first detaching part of the origin of the soleus from the -tibia, and then by freely cutting through the fascia which cavers the deep muscles j the artery will then be seen, a<- 157 c-ompanied by a vien on each side, and with the nerve on its fibular edge. It is an extraordinary circumstance that Mr. Hey, of Leeds, has advised us to cut out a piece of the fibula, in order to get at this artery. I have seen a patient, on whose leg my friend, Mr. Smith, of Leeds, tied the artery, with great ease, nearly in the same manner which I have now described. When there is a deep wound in the sole of the foot, it may be necessary to tie this artery. In such a case, we shoma dissect for it behind the inner ankle. The artery will be found under the fascia, and in the same rela- tion to the nerve as it is higher up; but the quantity of fatty substance which is here, will make it rather difficult to ex- pose the vessel. The fibular artery may be found at two hands' breadth from the heel, by cutting on the outside of the gastrocnemi- us, where it becomes tendinous. By turning up the edge of the tendon, the flexor pollicis magnus will be exposed. If the fascia which covers this muscle be not opened, we may perhaps come upon the posterior tibial ; but by opening the fascia, and detaching the fibrous origins of the flexor from the fibula, we shall find the artery under the acute margin of the bone, accompanied only by its venaB comites. After having attended to all the surgical questions con- nected with the anatomy of the arteries, we should consider of the most eligible positions for the relaxation of the mus- cles, in the different kinds of fracture ; and also the manner of distinguishing fractures from dislocations. When we open the joints, we shall be surprised to find the great number of instances in which the cartilages of the heads of the bone appear eroded. I have so frequently seen in all kinds of subjects, (and even in the joints of animals,) the appearance wliich is described by Mr. Brodie as ulcera- tion of the cartilage, that I cannot agree with him in suppo- sing that it is the effect of disease. I rather suspect that if is a change which very frequently takes place in the struct- ure of the cartilage, without any symptoms whatever being f he consequence of it. DISSECTION UPPER PART OF THE BODY As THE upper half of the body includes all the parts which are above the diaphragm, and the muscles of the back, it will be too much for a young student to undertake at once ; he should therefore begin with an arm, or one side of the head. But as these two parts are, according to the rules of the dissecting room, generally taken by the same student, I shall lay down a plan of such a series of dissections as will enable him to make the most of these parts, and which will, at the same time, be practicable while several pupils are en- gaged in dissecting the same body. As the student should dissect those parts first which be- come soonest putrid, he ought, on the first day, in union with his companion, to attempt to make a dissection of the princi- pal parts of the brain.* On the second day, he should dissect the superficial mus- cles of the neck ; and on the third day, the muscles of the face. On the fourth day, he may examine the deep muscles of the throat and of the jaw, and the general anatomy of the mouth. This plan may be very easily followed if the student can turn the body as he pleases ; but as I have supposed that there is another pupil engaged in dissecting the opposite s de of the head, his operations must also be taken into considera- tion. As it will be very inconvenient for both students to dissect the neck at the same time, they must either dissect at differ- ent hours, or one must pursue the dissections of the arm, while the other is engaged with the neck. But if both art young dissectors, the best plan will be, for the one to assist * Neither the arteries nor the veins should be injec.ted> 159 the other, as the dissection of the neck is very difficult for a beginner. The muscles on the fore part of the chest should be next dissected, and then the thorax may be opened, so that a gen- eral view of the viscera may be given ; after which, the heart and lungs; with the larynx, &c. should be removed, and put. into water, for future examination. At this stage of the dissection, the students who are dis- secting the lower half, will probaly be prepared either to make a section of the body, or to turn it. The superficial muscles of the back are then to be dissected. When these are finished, the arm should be separated from the trunk, by cutting through those muscles of the back and chest, which are inserted into the scapula, and by either dislocating the clav- icle from the sternum, or by cutting it through the middle. The arm should be wrapped up in a damp cloth, and laid in a cool place, until the dissection of the other part is finished. The deep muscles of the back and of the fore part of the nock should now be dissected. The vertebra? are then to be divided, so that the ligaments may be examined. If the student does not wish to preserve the scull, he should make such sections of it as will enable him to show the general anatomy of the nose, ear, &c. But before he exam- ines these, or dissects the ligaments, he should allow them to remain in water for some time : in the mean time he may dissect the muscles of the arm. After the muscles of the arm are dissected, he should examine the ligaments. In the second dissection of the upper half of the body, the arteries (having been previously injected) should be traced, with some of the principal nerves and veins. During this dis- sertion, the student should attend to the practical points of surgery ; but another body, in which the vessels are unin- jected, should also be devoted to this examination. In the third dissection, the brain and nerves should be more ijfirlv studied. 160 DISSECTION OF THE BR I SHALL at present describe only the common method of dissecting' the brain ; for, whatever changes may take place in our opinions regarding the nervous system, it will be al- ways necessary to be familiar with the natural appearances of the different parts of the brain, when it is dissected from above, downwards, because this has been the method gen- erally pursued in tracing the effects of disease or injury upon the brain. I think that the student will derive much advantage by dissecting the brains of the lower animals; because he will not only discover the meaning of certain names which are fiven to parts of the brain, but he will also find it to be the est and most interesting mode of investigating the anatomy in a physiological point of view. After he is familiar with the dissection of the brain of the pig, sheep, &c. he will be able to make the dissection of the human brain in a variety of ways. To prepare for the dissection of the brain, the scalp should be cut in the line of the coronal suture, from ear to ear; then the anterior portion is to be raised from the scull, and pulled down upon the face ; the posterior part should be carried to- wards the occiput. It is necessary to follow this plan in a private dissection ; for, unless we do so, we shall find some difficulty in making the parts appear decent after the dissec- tion is finished. In cutting through the scull, there is some nicety requir- ed. It should not be cut lower down, on the anterior part, than half an inch above the frontal sinuses; but the cut may be carried to a lower level behind. Before the saw is applied, a piece of whip-cord should be tied firmly round the scull, as a mark for the circular incision. The saw should not be carried through all the tables of the scull ; but after having cut through the external and middle tables, we should endeavour to break through the tabula vitrea,* with the *It is hardly necessary for me to remind the student, that in the child, the tables of the scull are not developed ; and 161 vln^I and mallet ; by proceeding thus, the dura mater will probably not be cut, which it is very difficult to avoid, if all the tables be sawed through. Although the bone may be completely divided, it will still be very difficult to raise the scull-cap, in consequence of the firm union which there is be- tween it and the Dura Mater. This forms an important point of demonstration, for it proves, that part of the dura mater is the internal periosteum. This is well exemplified in the scull of a child ; for there, it will be found impossible to raise the scull-cap, without, at the same time, cutting the dura mater ; even in the adult, it is necessary to use a lever between the portions of the scull, and then to pull it up, with some violence, before it will separate from the dura mater. When the adhesion is particularly strong, the separation may be facilitated by passing a whale-bone spatula, or the handle of the knife, between the dura mater and the bone. (a) When the scull-cap is torn off, we shall see pits and fur- rows upon its inner surface, and, on the dura mater, little fungous excrescences and vessels, corresponding to the pits and furrows in the bone. Tho fungi are most numerous on the parts opposite to the sagittal suture ; they are like soft warts, or pale granulations, and have been called Glowl-ufo Pacchiofii. If the arteries have been injected, the branches of the Meningea Media will be seen. The Anterior and Posterior Meningeal arteries are so small, that they will not be visible, until the brain is removed. If we make a puncture with the scissors into the most su- perior and central part of the dura mater, we shall pierce the .Longitudinal Sinus. If we pass a probe into this puncture, it may be pushed towards the occiput, and towards the fron- tal bone, thus showing the course of the sinus. The sinus may be opened, by cutting upon the probe. The first thing we shall observe in the sinus, is a body ge- nerally of a white colour ; but which, we shall find to be only a coagulum, that has taken the form of the sinus. The internal surface of the sinus is irregular, in consequence of * here being frequently many of the glandular Pacchioni in it ; and, from its being crossed by a number of small filaments. that, in extreme old age, they are all consolidated, it is only in the adult, that the three tables are distinct. (a) The adhesion between the dura mater and the inner table of the skull is from blood vessels entering the bone at every point, and from processes of the membrane passing out a H he sutures to communicate with the pericranium. 162 which, as well as a set of bands that are situated on the out- side of the sinus, have been called the Cordce Willisii. By putting the probe under one of these cords, we shall probably pass it into the mouth of one of the veins which enter, in a lateral direction, from the pia mater. We cannot prosecute the course of the sinuses farther, in this stage of the dissec- tion. Our next step must be, to raise the dura mater ; to do this, we should cut through it opposite to the ear, on both sides, and, with the scissors, carry the incision forwards nearly to the spine of the frontal bone, and on the back part, to the perpendicular ridge of the occipital bone. The lateral part* of the dura mater, may then be turned up towards the longi- tudinal sinus ; this will expose the substance of the brain, covered by the Tunica JLrachnoides and Pia Plater. In do- ing this, no adhesions will be found between the dura mater and the oths.r membranes, except at an inch, or half an inch,- from the sinus. This adhesion has a white, granulated ap- pearance, which has often been described as the effect of disease. When we tear this up, we shall see the veins of the brain entering into the sinus ; and by breaking down the connections on both sides, we may see* that prolongation of the dura mater, which is called the Falx, and which sepa- rates the upper part of the brain into Two Hemispheres; and by merely pulling aside the masses of the brain, and pass- ing down the handle of a knife between the hemispheres, we may expose this septum, in all its length. On its anterior part, we shall see that it is very narrow, and that it is attach- ed to the crista galli of the ethmoid bone ; as it passes back, -it is seen to increase in depth, until it becomes attached to the Tentorium; but the tentoriurn cannot be seen in this view, nor until a considerable part of the brain is removed. The scissors should now be passed between the anterior part, of the hemispheres, so as to divide the connection between the falx and crista galli ; the falx may then be pulled toward? the occiput, as a few small vessels are the only means of ad- hesion between it and the brain. The dura mater having; been thus laid down towards the occiput, we may examine the next membrane Tunica ArachnMea. If there be no effusion of serum on the surface of the brain, it will be diffi- cult to see the membrane, on account of its transparency; but when there is effusion, the membrane will be apparent, with-" out any -preparation, as the membrane will then be gener- aMy a little thickened. To show it, in all cases it is only ne- cessary to make such a puncture on the surface, as will ad- mit the point of the blow-pipe, the air will raise it in the form of vesicles. It is difficult to trace this membrane to ali: 163 Ui<- parts of the brain that it is said to go to. It is easy to trace it over the surface, passing from one convolution to another, without dipping between them, as the pia mater will be found to do. But it is said to be reflected on the inner surface of the dura mater, so as to give it its glistening- smooth appearance ; and it is also, by the French theorists described as passing into the ventricles, so as to cover their internal surface. When the base of the brain is exposed, the membrane will be seen to be much thicker at that part. The next membrane, the Pia Mater, is so distinctly seen through the last, that they have often been confounded. We see it loaded with arteries and veins, and when we pull upon a portion of it, we shall find that it goes down into the substance of the brain, and that it passes between the con- volutions. In the course of our dissection, we shall discover the pia mater in many parts of the interior of the brain, it being, in fact, the cellular membrane which supports the palp, and carries the several parts. We should now tear this membrane from one of the hemispheres, so as to show the convolutions. The surface of these convolutions will appear grey : but if we cut a slice off, we shall then see that the interior is of a white colour, from this circumstance, the surface has been called the Cine- ritious, or Cortical Part, and the internal, the Central, or Medullary. We should now separate the two hemispheres gently from each other, and then, by looking down between them, we shall see a white mass, and if the arteries have been inject- ed, two arteries will be perceived upon it : this white mass has been called the Corpus CallowmfoT, from the term Com- missure being given to the points of union between the se- veral parts of the brain, it has been called Commissura Mag- na, as being the largest. As we have nothing particular to remark in the structure of the upper part of the hemispheres, they may be gradually sliced down,* until we reach the level of the corpus callo- sum. In making these cuts, the relative disposition of the cmeritious and medullary matter will be seen to vary : about, an inch and a half from the surface of each hemisphere, the medullary matter will have an oval form, and be surrounded by a band of cineritious matter ; this is called the Centrum Ouale Parvum of Vicq-d'Azyr, and must not be confounded with the proper Centrum Ovate of Vieussens, which will be * In slicing the brain, we shall find that it will be done with more ease, if we occasionally dip the knife into water. 164 seen when both hemispheres are cut down nearly to a leve! with the corpus callosum, which we should now do. But we ought not to be too anxious to show this, exactly as an oval ; for, in doing so, we may cut so deep, as to open the Lateral Ventricles, if they should be distended with fluid. When this part has assumed the appearance of a large oval of medullary matter, we shall see, in the centre of it, the Corpus Callosum, and in the middle of this, there is a little furrow called Raphe, or Suture, which is formed by two lon- gitudinal ridges, running betv/een the anterior and posterior part of the brain. By examining the part closely, we may discover the fibres which run across, and are termed L'micf Our next object is, to open the Lateral Ventricdles. This may be very easily done, if there be water in them ; for we have only to slice down the medullary matter, horizontally. on each side of the corpus callosum, until the water flows out ; but we should preserve about a half, or three quarters of an inch in breadth of the corpus callosum, through its whole extent. It will be rather difficult to know when the Ventricle is opened, if there be no water in it (and this may be ascertained, by patting with the finger, on each side of the corpus callosum,) because the first part which will be seen, when the ventricle is laid open, is a grey mass; there being as yet no appearance of a cavity. But by insinuating a probe, or the handle of a knife, between this body (which is the upper part of the Corpus Striatimi] and the cut margin of the medullary matter, we shall be able to pass it, towards the frontal bone, into the cavity in the anterior lobe, and then into that in the posterior lobe. If the brain be firm, we may expose the cavities, by cutting upon the probe, or by taking out a piece with the scissors ; but the brain, when examined in the dissecting room, is generally so soft, that a knife, introduced like a bistoury, upon the probe, is sufficient to tear the medullary matter, still we ought not to do this, it' we can avoid it. Wnen both ventricles are opened in the same manner, we can understand how the corpus callosum is said to form the roof of the ventricles ; for it is now seen to .stretch from the anterior to the posterior part, in the form of an arch. If the brain be tolerably firm, we may be able to see the septum of the ventricles, which is formed by a thin lamina of medullary matter that passes down perpendicular- ly from the lower surface of the corpus callosum, towards the Jloor of the ventricle, and which we shall afterwards find to be formed by the Fornix. In consequence of this portion of medullary matter forming a transparent septum between the right and left ventricles, it has been called the Septum Lwd- 163 dum. But we shall very seldom get a brain sufficiently firm, to allow of the septum being seen. A small slip of writing paper should now be cut to the shape of the corpus callosuin, and laid on its upper surface ; this will give the corpus callosuin such a degree of firmness, that, after having cut it through at its anterior part, we shall be enabled to tear it back ; in doing this, the septum lucidum is necessarily destroyed, but we may observe, that, as it is torn, it separates into two laminae, that appear to have a ca- vity between them, and which has been called the Fifth Ven- tricle. When the corpus callosum is laid back as far as its con- nection with the medullary matter of the posterior lobe, th* Fornix will be seen, connected to the medullary matter ot the anterior lobe, and branching into two portions behind. Biit, in tearing back the corpus callosum and septum luci- dum, in a soft brain, we are very spt to tea* up a portion of the fornix, just at the point of its division, and thus to make the appearance of a hole in it. Before tracing the fornix, we should attend to the general form of the lateral ventricles. The cavities which have been already exposed, are called the Anterior and Posterior Horns or Sinuses ; but there is yet another sinus, which is called the Inferior or Middle Hern. This last should now be laid open ; but as it lies very deep in the middle 10be, it will be necessary to cut away a large quantity of the brairr. before we can show it. The knife may be placed oft the up- per part of the corpus striatum, and carried in a slanting di- rection, towards the angle formed by the union of the squa- mous and petrous portions of the temporal bone; and it may- be continued, in the same line, from the anterior to the pos- terior part of the brain. Even this large cut may not be sufficient to expose the inferior sinus; but in cutting more, we must proceed cautiously. The Posterior CVmofthe fornix will direct us to the opening of the sinus; we should; pass a probe, or the handle of a knife along the crus, and then cut upon it ; but as the sinus takes a sweep like a ram's horn, the turn must be cautiously followed. When the cavi- ties of both sides are exposed in their full extent, we may make our observations on the several parts which are in the two ventricles. We at once recognize the Corpora Striata ; for the incis- ions which have been made for the exposure of the inferior horns, exhibit the mixture of cineritious and medullary mat- ter, from which these bodies have got the name of corpora striata. We may now see that the Fornix is attached to the anterior lobe of the brain, by a part which appears single, but 166 which, we shall afterwards discover to be formed of two cords : however, this is generally called the Anterior Cms of the Fornix. If we trace the fornix backwards, we shall see it dividing into two parts, which are called its Posterior Cru- ra, and which diverge, and descend into the inferior horns. Between the fornix and the corpora striata, a reddish body will be seen ; this is part of the Plexus Choroides, which may be traced into the posterior horn, and also into the deepest part of the inferior horn: where it will be afterwards found to communicate with the pia mater which covers the base of the brain. If we now look into the posterior horn, we shall see a little medullary eminence, which has been called Hip- pocampus Minor, to distinguish it from a much larger emi- nence, of the same kind, which is in the inferior horn, and is called Hippocampus Major, from some resemblance which it has to a small marine animal. If we pull up the portion of the plexus which descends into the inferior horn, we shall see, that the hippocampus takes a turn somewhat like a ram's horn, whence it has sometimes received the name of Cornu Ammonia ; its extremity has a bulbous form, like the point of a finger, whence it is occasionally called Digital Process, and the extremity of the sinus, the Digital Cavity. At the first view, the hippocampus appears to be the continuation of the posterior crus of the fornix ; but, by following the crus, we shall find that it terminates in a thin layer of medullary mat- ter, which lies on the hippocampus : as this layer ^has soimr resembfance to a tape worm, it has been called Twnia, and to distinguish it from another taenia, it is called Tcenia Hip- pocampi, or, from its edge being, when in a fresh state, appa- rently fringed, it has also got the name of Tcenia Fimbriata. We should now examine the communication which there is between the two ventricles: If we trace the plexus cho- roides, we shall find it inclining towards the anterior crus of the fornix : if we then pass a curved probe, or small bougie, along the plexus, and under the anterior crus of the fornix, if will appear in the opposite ventricle. But it may be object* ed to tltis, that the brain is so soft, that the probe would meet with no resistance, were it to be passed through the matter of the fornix. The best proof we have of the exis* tence of a hole here, is by blowing on one side of the crus of the fornix, for the air will then pass into the other ventricle , or if we open the right ventricle, in a very fresh brain, and lay the head on the same side, the water will flow from the left ventricle through the hole. In cases of hydrocephalus, w r e shall sometimes find the hole large enough to admit the point of the finger. This opening has been, by some, called the Foramen of Monro ; but it is more generally called the For- 167 amen Commune Anterivs, as we shall afterwards find, thai if, also communicates with the third ventricle^ and with the Jnfundibulum, The fornix may now be cut at the point under which the probe has been passed, and may then be turned back ; but as the substance of the fornix is very soft, it should be strength- jnned by putting a piece of paper, of the same shape, upon it. When the fornix is thrown back as far as the point where it diverges, we may perceive upon its lower surface, white lines, something in the form of the strings of a lyre ; from this ap- pearance, the lower part has got thenameofiyra. We shall now have a complete view of the plexus choroi- des of each side, united together by a membrane which is ge- nerally called Velum Interpoxitum or Velum Vnsculosum^ or, from its similarity to the mesentery of the intestines, me- sentery of the plexus choroides. In the fresh and sound brain, the plexus and its velum will prevent us from seeing any of the Tkalamus which is below it ; but it generally happens, that the plexus of each side falls towards the middle, so as to expose a part of both thalami. If we examine the middle of the plexus, we shall see two veins passing backwards, to unite and form a larger one, the Vena Gal mi. We may trace this vessel back, by making it horizontal cut, on the level of the velum, quite to the occi- put, so as to remove all the remaining parts of the fornix and corpus callosum : the vein will then be seen entering into the fourth sinus of the dura mater, or Torcular Hierophi/i. which is just at the union between thefalx and tentorium. We should now raise the plexus choroides and velum from the anterior part, and carry it back ; but at first, we should not remove it farther than two inches. This will complete- ly expose the two white bodies which are called TKalumi JVe- vorum Opticorum. Upon their anterior part, we may see two little eminences, called the Monticuli ; and in the angles of union between the thalami and corpora striati, we shall see a streak of whitish matter, which has somewhat the form of a tape- worm, or piece of tape, whence it is called Tasnia ; and, from its direction, semicircularis ; and from its connex- ion with the thalami, which are sometimes called gemini, if has the word geminum added, Tcenia Semwircularis Gemi- num. On the anterior part of the thalami, we shall seethe open- ing which has already been described as forming part of the foramen commune anterius, If we direct a probe slantingly forwards, it will pass towards the part called Her ad infimdi- bulum ; if pushed on, it would pass through the substance of the infundibulum, and enter ihe Pituitary Gland. If the 168 probe b pulled out, and then passed downwards and back- wards, it will pass into the Third Ventricle. This open- ing has sometimes received the elegant name of Vulva > while the depression which may be now seen at the other ex- tremity of the thalami, has got the name of Anus. Thislat' ter opening is sometimes called foramen commune posterius ; but it differs from the anterior opening in this, that it is so covered by the velum interpositum, that there is no opening here until the velum is torn up. We may now trace the plexus choroides a little more. We shall find that it dips down behind the anus ; but we must be careful how we raise it at this part, for here it sur- rounds the Pineal gland ; therefore, the membrane shouJd not be rudely pul-led away, but should be dissected off with the forceps and scissors ; by which we shall expose a little reddish grey body, rather larger than a pea, and attached to the posterior part of each thalamus, by a little process or pe- duncle ; this is the famous Pineal Gland. When we take it between our fingers, we must not be surprised to find some gritty particles in it. We should now separate the tXalami gently from each oth- er, and we shall find that they are united by a grey mass, which is called the Commissura Mollis. The name implies, that this bond of union will be often dissolved before we reach this part of the dissection. The chink, or sulcus, which is seen on separating the thalami, is the Third Ven- tricle. If we separate the thalami to some distance from each other, and look towards the anterior part of the cavity, we shall see a white cord passing across it : this is called the Comnnssura Anterior ; we may see a similar cord on the posterior part, called the Commissura Posterior ; but to see these, and the third ventricle, more distinctly, we should now slice away a great part of the thalami and corpora striata. The next point of demonstration is the Nates and Tester, or Tuhercula Qwidragemma. It is rather difficult to expose these, as they^are situated in the space between the cerebrum and cerebellum. All the part of the posterior lobe which is lying on the tentorium, should be removed, and then the ten- torium should be cut through on each side, so as to expose the upper part of the cerebellum, the projecting part of which (processus vermiformis superior) is to be held down ; the four little eminences will then be seen ; the two superior being called the Nates, the inferior, the Teate-s. The next stage of the dissection is difficult ; for we ought now to expose the cavity of the Fourth Ventricle, which fies between the cerebellum and medulla oblongata. If we 'pass a probe, slightly curved, from the third ventricle, under tire 169 posterior commissure, and give it a direction downwards and backwards, it will pass into the fourth ventricle, the passage being called Iter a Tertio ad Quartum Ventriculum, or by the old name ofAquce Ductus Syivii. If we hold back, or slice away, the upper part of the cerebellum, and raise the probe, we may perceive it under at hin lamina of medullary matter^ which is the roof of the fourth ventricle, and is sometimes cal- led falvufa Cerebri, or Valvula Vieussenii ; by cutting through this, we may look into the cavity of the fourth ven- tricle : and now we may observe, that this valvula cerebri is connected with, or formed of two cords, running from the nates and tostes to the cerebellum; these cords are each cal- led Processus a Cercbello ad Testes. There are two or three different modes of exposing the ca- vity of the fourth ventricle more fully. One way is, to car- ry the knife down perpendicularly, so as to divide the cere- belluqjpnto two portions ; but the best way of examining it, is to cut out a triangular portion of the occipital bone, down to nearly as far as the foramen magnum. When the bone is removed, we shall see the cerebellum connected at the lower part, by the pia mater, to the beginning of the spinal marrow ; this portion of membrane is the only boundary which the fourth ventricle has on its lower part, so that it" we tear it, we shall open the cavity. By lifting the cerebel- lum, we shall expose the sulcus on the upper part of the spi- nal marrow, which has been called the Calamus Scriptorium ; then, by dividing the cerebellum vertically into two equal portions, we shall see the whole extent of the fourth ventri- cle, and also the appearance in the cerebellum which is cal- led Arbor Vitce. But before making this section, there are two parts of the cerebellum to attend to ; the names are ve- ry absurd, but, since they are always mentioned, we must de- scribe them. Processus Venniformis Superior, is the name sjiven to the little eminence on the highest portion of the cer- ebellujn, as it has some resemblance to a worm coiled up ; this is the same part which we were obliged to hold aside, or .out away, in showing the nates and testes, and valvula cere- bri. When we look at the lateral parts of the base of the cerebellum, upon the side of the sulcus which corresponds to the falx cerebelli, (and which has been removed in cutting the occipital bone,) two little convolutions will be seen, which, from some faint resemblance they have to worms, have been called the Inferior Vermiform Processes. The method just pointed out, is the best manner of giving an accurate notion of the relation of the fourth ventricle to tire other parts, of the brain ; but if we object to it, in conse- quence of the scull being hurt by cutting out the portion of 170 the occipital bone, we must raise the base of the brain from the scoff, before we can examine the parts in the fourth ven- tricle. But in doing this, there are several points of anato- my which should be noticed, previous to the examination of the ventricle. The scull should be allowed to fall back a little, and then, with the handle of the knife, we should lift part of the ante- rior lobe from its position on the frontal bone. In doing so, in a very fresh brain, we may see the Olfactory Nerves (I.) passing into the cribriform plate of the ethmoid bone ; but this nerve is so soft, that, in general, it is destroyed before we reach this stage of the dissection. In turning the lobes farther back, the Opiic Nerves (II.) with the Carotid drtciy rising by the side of J^hem, will be distinctly seen. These nerves should be eut across at their entry into the foramen opticum. The arteries, if injected, should be divided as far down as possible ; but if they are not injected, it isgiot of consequence where they are cut. On cutting througrr the^e parts, we should attend to a little red projection which passes towards the sella turcica ; this is the Infnndilwhim, which is attached to the Pituitary Gland, The next nerve theJWotor O0w&V(Iiy will be easily discovered ; but the Trochlearis (IV.) is difficult to find ; for it is not only very small, but it lies within the fold of the dura mater which passes from the tentorrum to the sphenoid bone ; when discovered, it should be cut, not torn. The next nerve, the Trigeminus, (V.) will be easily seen, as it is very large, and goes off in a lateral di- rection. The Mducens (VI.) will be seen to run in the same direction as (III.) (It generally happens, at this stage of the dissection, that the brain has fallen so far back that it must be supported, or the weight of the anterior part may tear it through.) After observing the (VII.) which is divided into two parts, Portio J^lollis and Portio Dura^ if we look jrtown towards the foramen magnum, we shall see the scattered fi- bres coming up to form the (VIIL) which is composed of three nerves, viz. Glosso Pharyngeal, Par Vagvm, and Spj- nal Accessory. In cutting them across, we must endeavor to leave the last nerve entire, as it comes up from within the spinal canal, to unite with the other. The fibres forming the Lingualis (IX.) will be easily seen. The brain will now be held in its place, only by the spina) marrow and the vertebral arteries ; the latter are to be snipped across, and then the spinal marrow is to be cut- through, as low down as we can carry the knife. We should now lay the brain on a wet board, and make thai 177 give it the appearance ef fungus. But if the tumor arise af- ter exfoliation of the bone and sloughing 1 of the dura mater, there will probably be a greater proportion of lymph on the surface ; which has led some to doubt the fact of there ever being a protrusion of the substance of the brain itself. In this latter case, an abscess will generally be found, extend- ing from the fungus to the ventricle. When a patient dies in a fit of apoplexy, we shall sometimes find only a very small clot, but occasionally, a mass of firm blood weighing some ounces. Where there is a large coagulum, the substance of the brain will be firm, and its vessels empty. In the greater number of these apoplectic cases, it is very difficult to discover the source of the bleeding ; and it is, with much reason, supposed to be frequently from very small vessels ; but if the patient has been suddenly seized while drunk, and struggling, there will probably be rupture of a large vessel. If a patient has survived an attack of apoplexy, we may discover the cavity in which the coagulum lay, - The sides of it will be smooth and tough ; and there will be serum, in place of the ceaguluia, which has beer, absorbed. If a man has been suddenly killed, while in a state of health, the ventricles will, on examination, be found to be merely lubricated with a fluid ; but in all cases where pa- tients die of protracted disease, more or less water will be found in the ventricles. In the acute hydrocephalus, there is frequently several ounces : but in the chronic hydrocephalus, the quantity of water will correspond to the size of the head, as in this disease, the iftass of the brain forms a mere sac for the water. The state of the plexus choroides should be compared with the appearance of the pia mater, for it will generally corres- pond with it. Small cysts, like hydatids, are so frequently found attached to the plexus choroides, that we can hardly consider them to be of importance ; but there are a few examples on record of very large cysts, or hydatids, having been found in the sub- stance of the brain. In the Museum, in Great Windmill Street, there are two very fine specimens; one of them con- tained four ounces of fluid. The Pineal gland is sometimes very soft ; at other times it appears like a vesicle. I have so frequently found it in oth of these states, that I cannot attach more importance to them, than to the gritty matter which is so often found in it. So far, the examination should be conducted nearly in the same manner as that described for investigating the natural anatomy ; but to prosecute it farther, the braiu should be 178 raised from the base of the scull. I shall endeavour to make my remarks correspond with the order in which the parts will be presented when the brain is raised from the anterior, and carried towards the posterior part. I shall, therefore, first observe, that if there has been disease of the ethmoid bone, as from polypus of the nose, venereal caries, &c. we may expect to find a corresponding state of the anterior lobes of the brain. It may be laid down as a general rule, that the carotid and vertebral arteries are always more or less ossified in a person above the age of fifty. If a person has been blind of one eye, we should examine the corresponding optic nerve, which will probably be small and transparent, and endeavour to trace it to the thalami, so as to assist in deciding whether the nerves always decus- sate (for it is still a question ;) though I may here observe, that when the left eye was blind, I have always found the right troctus opticus much smaller and more transparent than the other ; and vice versa. If there be matter in the cerebellum, we should look to The state of the temporal bone; for scrophulous caries in this bone will often be the cause of disease in the brain. When there is water found lodging upon the scull after the brain is removed, we must not suppose that it has existed there during the life of the patient, but that it has escaped from the several cavities during the dissection, and has fallen down to this part. It may even fall into the sheath of the spinal marrow ; but it must be, at the same time, admitted, that when there is water in the ventricles of the brain, there will be generally some found between the spinal marrow and its membranes, and perhaps even without disease, for in the prosecution of experiments on the spinal marrow of the ass, I have had occasion to open the sheath several times be- tween the occiput and atlas; and in every instance, imme- diately on puncturing it, about two ounces of clear limpid fluid have escaped in a stream. This I have noticed, in a proportionate degree, in other animals. In consequence of the difficulty in opening the spinal ca- nal, we are frequently unable to ascertain positively, whether the parts within, are diseased or not. Of late years, it has been a common opinion, that the spinal marrow is violently inflamed in cases of tetanus ; but I suspect that in the greater number of the cases which have been related, that the ap- pearance produced by the gravitation of the blood after death, has been mistaken for inflammation : and this I have been more convinced of, since I lately, with a view to ascer- tain the truth of this, examined the tody of a man who haU 179 died of tetanus. Immediately on the death of the patient, T got the body laid upon the belly, instead of the common po- sition : upon opening- the spine, there was no appearance of that loaded state of the vessels on the posterior column, which has been considered as a proof of the previous exis- tence of inflammation of the spinal marrow ; but the ante- rior portion, which, in this case, had been the most depend- ing 1 part while the blood was gravitating-, was covered with a congeries of distended vessels. I may here also observe, that if, in opening the spine, we puncture the membranes of the. spinal marrow, that part of the nervous pulp will be for- ced out in the form of a tumour. This will perhaps account for many of the tumours which are discovered in the spinal marrow. But it is not my intention to deny either the occa- sional inflammation of the spinal marrow, or the existence of tumours in it ; for I have several times seen tumours, of firm consistence, in it, arid similar to those which are occa- sionally found in the brain. I have also, in many instances, seen the membranes highly inflamed, and even matter on their surface, which has extended down to the cauda equine. INVESTIGATION OF THE STATE OF THE HEAD' IN CASES OF SUDDEN DEATH. When called upon to investigate the state of the head in cases of sudden death, or of death from injury, we must be particularly guarded in giving an opinion : for it is exceed- ingly difficult to ascertain, whether many of the appearances are attributable to injury, or to previous disease, or to a change which has taken place after death. Of the difficulty of coming to a decision on this subject, I am the more con- vinced, the greater number of bodies I examine. But as I cannot enter into the question fully, I shall only give a few hints ; which, however, 1 hope will induce the student to in- vestigate the subject further. The first thing we should know, is, that there is, very fre- quently, an appearance of bruises on the scalp; which, how- ever, is only the effect of pressure on a particular part of the head, when the scalp is cedematous and loaded with Wood. The question whether there has been a fracture previous to death, is sometimes more difficult to decide, than a per- son, who is not accustomed to dissection, could imagine. If the fracture has occurred immediately before the patient's death, there will be coagulated blood found upon the bone, and in the fissures ; but if the patient hat? survived foj- some 180 time, there will be marks of inflammation, and perhaps pus in contact with the scull. If a fracture has been produced in making the examination, (which sometimes happens even in a very careful dissector's hands,) the blood in the fracture Will not be coagulated, nor will there be any effusion around the portions. If there have been symptoms of fracture after a blow on the upper part, and. if we cannot discover one op- posite to the part struck, we should look to the temples, or to the base of the scull. It has been already remarked, that a blow on the scalp may be followed by abscess in the brain ; but we ought to re- collect, that a blow, which, in a greater number of constitu- tions, would be a mere trifle, may, in certain habits, be at- tended by a train of symptoms which may cause death. If effusion of blood be found between the dura mater and scull, and if a bruise on the scalp corresponds to the part, we may conclude, that it has been caused by the blow ; but if blood is found between the dura mater and the brain, though we should discover the marks of blows, or even frac- ture of the scull, still the question may be, might not the patient have been attacked with apoplexy during a struggle ? 'An interesting question of this kind occurred at the York Assizes, in the summer of 1820. But I shall here introduce the history of a case which occurred about twelve years ago, and at the dissection of which I assisted. This case has always made a great impression on my mind, for, as I was then very young, I might have given a very erroneous opin- ion upon it. It is related in Dr. Cheyne's Treatise on Apoplexy. " An industrious man returning home from hi? work, found riis house empty of every thing, the bed he was to lie upon, and the tools of his trade, sold for gin by his wife, whom he found in a gin shop, where she had been drinking and dan- cing. He brought her home, and in the passage of his house struck her, and ordered her to go up stairs. She refused ta go ; he carried her upon his shoulders, and the contention continuing up stairs, he struck her again. There having been no one present, we have only the husband's account of her death. He said, that whilst sitting on her chair, she fell down, upon which he threw her on the bed, conceiving she was in a fit, such as he had seen her in formerly. Some of her neighbors coming in, found her dead. Mr. C. Bell was Tequested to examine the body of this woman. The man Was afterwards tried at the Old Bailey for murder, and Mr. Bell's deposition was nearly to this effect. In the abdometx and' thorax, nothing appeared remarkable, further than thai the stomach contained a quantity of gin ; and that then* was 181 a blush of redness on the lower orifice of the stomach and duodenum. On the head, there were several bruises ; but the bone was not at all hurt, and no extravasation appeared under the bone. On exposing- the membranes of the brain, the vessels of the pia mater were empty of blood, as if from pressure. There was a serous effusion under the tunica arachnoidea, and in the cavities of the brain, similar to what has been found in those who have died from intoxication. On the surface of the brain, there were what appeared to be spots of extravasated blood ; but upon tracing- them towards the base, they proved to be streams of blood which had flow- ed from a vessel ruptured in the base of the brain. The base of the brain was covered with coagulated blood, in which al- so, all the roots of the nerves were involved. On dissetting the cavities of the brain, the blood was found to have pene- trated into the third ventricle, by perforating- its floor. Upon taking out the brain, and tracing the vessels in the base, the anterior artery of the cerebrum going off from the internal carotids of the left side, was found torn half way across : from this source came the extravasated blood. k< The cause oftiiis woman's death was the bursting 1 of the blood from the ruptured vessel, and the pressure on the brain, or, more correctly speaking, on the vessels of the brain. A? to the cause of the rupture, Mr. Bell's opinion coincided with the best authorities in pathology, that there is a state of the vessels in which an external injury or shock is more apt to produce rupture, and drunkenness may be supposed to be tiie artificial state of excitement, which most resembles this state of the vessels. Being asked whether the blows were the cause of the rupture ? he said he conceived it very likel y that a shock would rupture the vessel : and being then asked whether he conceived that this woman was more likely to have a vessel ruptured from having been intoxicated ? he was of opinion, that intoxication, and the struggle, were like- ly to produce such a degree of activity of the circulation in Uie head, that a less violent blow might produce rupture than what, in other circumstances, would have proved fatal." The man was acquitted. 182 DISSECTION OF THE MUSCLES ON THE FORE PART OF THE NECK. Ptaiysma Nyoides is the first muscle to be disserted. The fibres of this muscle are frequently so thin and indi.-tinrt that a student will find it sometimes difficult to expose them, particularly as they have neither origin nor insertion in bon?. A block of wood should be put under the shoulders, arid the head should be fixed by a chain hook to the table, .so as to make the fibres of the superficial layer of the muscles tense.* An incision should then be made through the skin o?/fy, iron] midway between the chin and the ear, to about three fingers' breadth from the sternal end of the clavicle. This incit ion will expose the fibres of the platysma, about their middle. The dissection should be continued, by cutting in the same line, first towards the larynx, and then towards the back part of the neck. In dissecting towards the fore part, the fibres of the sterno hyoideus will probably be in part exposed ; and towards the back part, the fibres of the sterno cloido mat-toi- dens will appear under the fascia, or condensed cellular mem- brane, in which the fibres ot the platysma terminate. The platysma may be cut across., about its- middle. The lower half is then to be carried toward*? the chest, by which we shall expose the fibres of the sterno cleido mastoiueus ; but in doing this, we should begin at the inner angle of the flap, and dissect in an oblique direction, or we shall be ob- liged to cut in a line across the fibres of the tsterno cleido rnastoideus muscle, which will increase the difficulty of rais- ing the cellular membrane. 1 he f-.ame thing is to be recol- lected in lifting the upper portion. When the platysma is raised, we shall see a number of glands on each side of the bterno cleido maetoideus , but these we may cut away without paying particular attention to them in the present dissection. The muscles which run from the jaw to the oshyoides, and those from the sternum to the game point, will be now par- * Previous to the dissection of these muscles, the student should particularly examine -the os hyoides, and the external cartilages of the larynx. 183 tially exposed : but previous to dissecting either of these sots of muscles, the origins and insertions of the Sterno Clei- do JWasttoiden* should be shown, after which the muscle may be cut through about the middle ; one half of it is then to be carried up towards the occiput, and the other towards the clavicle. There will now be little difficulty in exposing the small muscles, for the course of the fibres of several of them will be seen under a thin layer of cellular membrane. The Sterno Hyoideus , which is the most superficial, may be shown in its whole extent. But at present, we cannot exhibit the origin of the next muscle, (the Onio Hyoideus,) be- cause it arises from the scapula ; but by dissecting towards the shoulder, we shall find a central tendon, which divides this muscle into two parts, whence, besides the common name of 01110 hyoideus, it has been called Digastricus, and the term Inferior is also added to it, as there is another dou- ble bellied muscle situated under the jaw. The muscle which will be partially seen between the two last, IB the Sternff Tfvyr&ideiis. To expose it fully, the ster- 110 hyoidous should be cut through the middle, or held aside. In dissecting 1 the sterno thyroideus, the young student is ve- ry apt to raise the origin of the Thyro Hyoideus ^ which runs from the thyroid cartilage to the os hyoides, and thus to give the appearance of two sterno hyoidei muscles. When the sterno thyroid is raised, one half of the Thyroid Gland will be seen ; and if it be pulled aside, the small muscle which passes from the cricoid cartilage to the thyroid, (Crico Thy- roideux,) may be shown. The dissection of the muscles which run from the jaw to the os hyoides, should now be made. \s the most superficial mnscie, the Biventer Superior, is composed of two parts, it will be necessary to dissect in two ijinv.rpiit, directions, to expose its fibres. The origin of the portion which runs from the mastoid process towards the os hyoide-;-?, may be first dissected. To see its origin, we must raise the lobe of the para.ti'1 ; and in showing the connection of its middle tendon with the os hyoides, (which is only by a. ligament,) we must take care that we do not cut through the fibre* of the stylo hyoideus, which is perforated by it. The maxillary half of the muscle is to be dissected by carrying the knife in a direction from the chin to the os hyoides. The next muscle to be dissected, is the 'Jlfylo Hyoideus, But. before its middle fibres can be seen, that part of the sub- maxillary gland which lies upon it, must be removed ; nor w.U its attachment to the centre of the jaw,' or its connection 184 with its fellow, be seen, until the anterior portion of the bi- venter is raised. If the mylo hyoideus be carefully raised from the jaw, and and from its connection with the mylo of the opposite side, the Genio Hyoideus will be seen running from the jaw to the os hyoides : but it is so closely attached to its fellow, that the two muscles appear to form only one. There is another set of fibres which take nearly the same origin as the genio hy- oides ; but as these fibres run both to the os hyoides and to the tongue, the muscles which they form is called Genio Hyn Glossut. Certain fibres may now be seen passing from the os hyoides to the tongue, to form the Hyo Gtossus, on the inside of which may be found a set of fibres, running from thr base to the tip of the tongue, to form the Lingitalis. The next object of the dissection should be, to display the lateral muscles the Styloid. To do this, the lower portion of the parotid gland should be raised, and the origin of the digastricus should be cut. When this is done, some of the branches of the carotid will be exposed : but these, at pre- sent, may be cut through. Three muscles may now be easily shown, running from the styloid process : one, to the os hyoides ; another, to the tongue ; and the third to the pharynx. As each of these muscles is named according to its origin and insertion, they are called Stylo Hyaideus, Stylo Glossus, and Stylo Pharyngi- tis. The dissection of them will be facilitated by pulling the os hyoides downwards, and towards the opposite side. The dissection of the muscles of the neck should not be prosecuted farther, until those of the face are dissected. TABLE OF THE SUPERFICIAL MUSCLES OF THE NECK. LATISSIMUS COLLI,OR PLATYSMA MYOTDES. OR. By ma- ny delicate fleshy fibres, from the cellular substance which covers the upper parts of the deltoid and pectoral muscles. They pass over tlie clavicle adhering to it. They ascend obliquely, to form a thin muscle, which covers all the side of the neck. IN. 1. The fascia on the base of the lower jaw; 2. the de- pressor anguli oris, and the fascia on the cheek. USE. It is said to assist the depressor anguli oris in draw- ing the skin of the cheek downwards ; and, when the mouth is shut, it draws all that part of the skin to which it is con- nected below the lower jaw, upwards. The true use of th*- muscle, is, to assist the respiration and circulation. 185 STERNO CLEIDO MASTOTDEUS. OR. 1. The top of the tsterjmrn, near its junction with the clavicle; 2. the upper and anterior part of the clavicle. IN. The mastoid process of the temporal bone and mastoi.- dean angle. USE. To turn the head to one side, and bend it forwards. STERNO HYOIDEUS. OR. 1. The cartilaginous extremity of the first rib; 2. the upper and inner part of the sternum ; 3. the clavicle, where it joins with the sternum. IN. The base of the os hyoides. USE, To pull the os hyoides downwards. OMO HYOIDEUS, OR BIVENTER INFERIOR. OR. The supe- rior costa of the scapula, near the semilunar notch, and the ligament that runs across it. Ascending obliquely, it be- comes tendinous below the -sterno cleido mastoid muscle : it grows fleshy again towards its IN. Into the^base of the os hyoides. USE. To assist in pulling down the os hyoides. STERNO THYROIDEUS. OR. The edge of the triangular portion of the sternum, internally, and from the cartilage of the first rib. IN. The inferior edge of the thyroid cartilage. USE. To draw the larynx downwards. THYRO HYOIDEUS. OR. The lower part of thyroid car- tilage. l.\. Part of the base, and the cornu of the os hyoides. CRTCO THYROTDEUS. OR. The side and fore part of the eric oid cartilage. IN. The lower part of the thyroid cartilage, and its infe- rior conm. Dro ASTRICUS. OR. The groove in the mastcld process of the temporal bone ; it; runs downwards, and forwards. The tendon passes through the stylo hyoideus muscle, and is fixed by a ligament to the os hyoides ; then the tendon is reflected forward, and upward, and becoming again muscular, it has an IN. Into a rough part of the lower jaw, behind the chin. USE. To open the mouth, by pulling the lower jaw down- wards; when the jaws are shut, to raise the larynx, aud^ consequently, the pharynx, in deglutition. MYLO HYOIDEUS. OR. All .the inside of the base of the lower jaw. IN, 1. The lower edge of the basis ef the os hyoides; $, iiito its fellow, of the opposite eide. 186 USE. To pull the os hyoides upwards. GENIO HYOIDEUS. OR. A rough protuberance within tht- arch of the lower jaw, which forms the chin. IN. The basis of the os hyoides. USE. To raise the chin. GENIO Hro GLOSSUS. OR. The rough protuberance on the inside of the lower jaw. IN. The tip, middle, and root of the tongue, and base of the os hyoides, near its cornu. USE. According to the direction of its fibres, to move the tongue; to draw its root, and the os hyoides, forwards ; ,and to thrust the -tongue out of the mouth. HYO GLOSSUS. OR. The base, cornu, and appendix of the os hyoides* IN. The side of the tongue. USE. To pull the tongue into the mouth,, or to draw it Downwards. LINGUALIS. OR. Base of the tongue. IN. Tip of the tongue. STYLO HYOIIJEUS. OR. The middle and inferior part of the styloid process. IN. The os hyoides, at the junction of the base and cofnu, USE. To pull the os hyoides upwards. STYLO GLOSSUS. OR. The styloid process, and from & ligament that connects that process to the angle of the lowo? jaw. IN. The root of the tongue, being insensibly lost oa the side and tip of the tongue. USE. To draw the tongue laterally or backwards. STYLO PHARYNGEUS. OR. The root of the styloid process. IN. The side of the pharynx and bade part of the thyroid cartilage* 187 DISSECTION OF THE MUSCLES OF THE IF the scull be still entire, an incision should be made,, through the skin , from the middle of the parietal bone to the ex- ternal part of the eye-brow, and another, from the crown to the tip of the nose. The object of the first incision, is, to expose the muscular fibres of the Occipito Frontalis ; and that of the second, to show those fibres which pass down on the nose. The next incision is to be made in a semicircular direction over the. eye-brow, so as to meet the two first incisions. Another may then be made under the eye-brow, and be con- tinued round the orbit, so that the eye-brow will be left, and the fibres of the Orhicularis Oculi be exposed. After completing- the dissection of the occipito frontalis and the orbicularis oculi, with the Corrugator Supercilii, which will be exposed by cutting through the nasal fibres of the occipito frontalis, we should pass to the dissection of the muscles of the mouth. An incision is to be made round the mouth, leavivg a small- part of the lip : this will expose the Orbicularis Orw, into which the other muscles are inserted. By then carrying an incision from the zygomatic process to this circular cut, the Zygumatic Muscles will be exposed ; and if another is con- tinued down to the angle of the jaw, from the same point, the fibres of Masseter will be seen ; but in doing this, we must take care that we do not wound the parotid duct, which grosses the face, nearly in a line drawn from the upper part of the lobe of the ear, to the ala of the nose. By dissecting down the flap of skin between the two last fijts, the Buccinator will be exposed. A large portion of fat will be generally found running between this muscle and the edge of the masseter, but it is so loosely attached, that if may be pulled away with the fingers. As in this dissection, we do not value the skin, we should make another cut from the angle of the mouth, obliquely, towards the outer part of the jaw, so as to expose the Triangularis, or Depressor An- gttli Oris. The muscles which have been named, may be fully sjiowft. by dissecting in the direction of ti? incisioira pointed out . 188 but the dissection of many of the muscles of the mouth will be found very difficult, and particularly those about the chin, on account of the mixture of their fibres with the integu- ments into which they are inserted.* The muscles of the nose and upper lip, may now be dis- sected. A cut should be made from the inner angle of the orbit, down to the middle of the circular cut round the mouth : this will expose the fibres of the Levator Lftbii Superior^ Alec- yue JVcm, between which, and the zygomaticus, the Levator Anguli Oris will be found; and if we raise the levator labii superioris alseque nasi, the Levator Propriwt will be seen. The Compressor., or Dilator JVhHs, may be exposed, by dis- secting down from the cut that was made from the tip of the nose towards the last incision. There are still two muscles to be shown, viz. the Super- fc.w.9, or Levator Labii Inferiors* and the Depressor Labii Su- perioris. To show the superbus, we should turn flown the lower lip, and dissect the membrane from the root of the in- cisores. The Depressor Labii Superioris will be found, by lifting the upper lip, and raising the membrane which covers the upper incisores. TABLE OF THE MUSCLES OF THE FACE. ARRANGED IN THE ORDEJR IN WHICH THEY ARE TO BE His SECTED. OrcipfTo FFIONTALIS. OR. The superior transverse ridgr- of the occipital bone, and part of .the temporal bone. A ten- dinous web covers the cranium, which terminates forward deahy belly (the frontal portion:) this muscular portion ers the frontal bone. I.N. 1. Into the orbicularis palpebrarum ; 2. into the skin of flic eye-brows. It sends down a fleshy slip upon the nose. USE. It draws up the skin of the forehead, and raises the r-ye- brows, CORRUG \TOTI SUPERCILII. OR. The internal angular process of the os frontis. IK, The skin under the eye-brows, near the middle the arch. *The dissection of these muscles will be facilitated by put- ting a little, horsehair into the mouth. 189 USE. We have no power over the individual muscle. The corrugators knit the eye-brows, and are antagonists of the last muscle. ORBICULARTS OCULI. OR. 1. By many fibres, from the edge of the orbitary process of the superior maxillary bone ; '2. from a tendon near the inner angle of the eye. These run a little downwards, then outwards, over the upper part of the cheek covering the under eye-lid, and surround thp external angle. Being loosely connected only to the skin and fat, they run over the supercilary ridge of the os fron- tis, towards the inner canthus, where they intermix with those of the occipito frontalis and corrugator supercilii ; then, covering the upper eye-lid, they descend to the inner angle, opposite to the inferior origin of this muscle, adhering firmly to the internal angular process of- the os frontis, and to the short round tendon which serves to fix the palpebree and muscular fibres arising from it. IN. The nasal process of the superior maxillary bone, co- vering 1 a part of the lachrymal sac. This muscle should be divided into the external and inter- nal muscles, the internal is the Ciiiaristh&t covers the car- tilages of the eye-lids, which are called cilia or tarsi. OH.BTCULARIS Oais. This consists of circular fibres, which surround the mouth, and constitute a great part of the thick- ness of the lips. USE. To shut the mouth, and to oppose the muscles which converge to be inserted into the lips. Part of this is sometimes described as a distinct muscle, viz. NASALIS LABII SUPERIORIS. OR. The fibres of theorbi- cularis muscle. IN. The lower part of the septum nasi. USE. To draw down the point of the nose, by operating on the elastic septum. ZYGOMATICUS MAJOR. OR. The zygomatic process of the os malae. IN. The angle of the mouth. USE. To draw the corner of the mouth obliquely upwards. ZYGOMATICUS MINOR. (Often wanting.) OR. The up- per prominent part of the os malee, above the origin of the former muscle. IN. The upper lip, near the corner of the mouth, along with the levator anguli oris. USE. To draw the corner of the mouth upwards. 190 DEPRESSOJR ANGUI.I ORIS. OR. The base of the maxillary bone near the chin. IN. The angle of the mouth, uniting with the zygomaticus majorandlevator anguli oris. USE. To pull down the corner of the mouth. DEPRESSOR LABII INFT RTORIS, OR QUADRATUR GEN*:. On. Broad and fleshy, intermixed with fat, from the inferi- or part of the lower jaw next the chin ; runs obliquely up- wards, and is IN. Into the edge of the under lip; extends along one half of the lip, and is lost in its red part. USE. To pull the under lip and the skin of the side of the chin downwards, and a little outwards. BUCCINATOR. OR. 1. The alveolar part of the lower jaw ; - ternal cartilages will be exposed ; the first that are seen, will be the two which run from the back part of the cricoid cartilage to the arytenoid cartilages, whence they are called the Crico Arytenoidci Poslici. By then pulling the thyroid cartilage a little from the cricoid, a similar set of fibres will be seen on each side, passing from the lateral part of the cri- coid to the arytenoid ; these are called the Crico Arytewoidei Laterales. A considerable mass of fibres may now be ob- served, passing from one arytenoid cartilage to the other, This is divided into three muscles, there being a. Transfer- xnltSi and two Oblique. The fibres which run directly a R 194 ibrm the transversalis, and may be always easily shown ; but the oblique are so small, being merely three or four delicate fibres that pass from the base of one cartilage, to the tip of the other, that they are often cut away with the mucous membrane. There are still three other muscles described, as running from one cartilage to another ; but it will be only in the la- rynx of a very powerful man, that we shall see them dis- tinctly. The names which are given to them, are suffi- ciently descriptive of their course, Thyro Arytenoideus^ Thyro Epiglottideus, Aryteno Epiglottideus. The only mus- cle which is on the fore part of the larynx, is the crico thy- roideus, which, in the first dissection of the neck, was seen passing from the cricoid to the thyroid cartilage. We may now remove the small muscles, so as to show the cartilages and their ligaments, which are named according to the cartilages which they unite together. TABLE OF THE MUSCLES OF THE JAW, AND OF THE DEEP MUSCLES OF THE THROAT. TEMPORALIS. OR. The semicircular ridge of the lower and lateral parts of the parietal bone ; 2. the pars squamosa of the temporal bone ; 3. the external angular process of the OB frontis ; 4. the temporal process of the sphenoid bone ; 5. it is covered by an aponeurosis, from which it also takes an ftriein. The muscle pa,?emg under the jugurr^ has for its IN. The coronoid process of the lower jaw, which it grasps with a strong tendon. USE. To raise the lower jaw. MASSETER. OR. 1. The superior maxillary bone, where it joins the os males ; 2. the inferior part of the zygoma, in its whole length. IN. The outside of the angle of the upright part of the lower jaw. USE. To pull up the lower jaw, for performing the grind- ing, or lateral motions therei PTERYGOIDEUS INTFRNUS. OR. 1. The inner and upper part of the internal plate of the pterygoid process of the sphenoid bone ; 2. the palatine bone. It fills the space be- tween the two plates of the pterygcid process. IN. The inside of the angle of the lower jaw. USE. To move the jaw laterally. 195 PTERTGOIDKUS EXTERNUS. OR. 1. The outside of the external plate of the pterygoid process of the sphenoid bone ; 2. part of the unper maxillary bone adjoining. IN. The outside of the angle of the upright part of the lower jaw. USE. To pull up the lower jaw, for performing the grind- ing, or lateral motions there. CONSTRICTOR ISTHMI FAUCIUM. OR. The side of the tongue, near its root ; from thence running upwards, within the anterior arch of the fauces. IN. The middle of the velum pendulum palati, at the root of the uvula. It is connected with its fellow. TENSOR, or CIRCUMFLEXUS PALATI. OR. 1. The spinous process of the sphenoid bone, behind the foramen ovale; 2. the Eustachian tube. It then runs down along the pterygoi- deus internus muscle, passes over the hook or internal plate ofthe pterygoid process, and spreads into a broad membrane. IN. The velum pendulum palati. Some of its posterior fibres join with the constrictor pharyngis superior, and pala- to-pharyngeus. USE. To stretch and draw down the velum palati. LEVATOR PALATI. OR. The extremity of the pars petror .su of the temporal bone, near the Eustachian tube, and from the membranous part ofthe same tube. IN. The velum pendulum palati, and the root ofthe uvula. It unites with its fellow. USE. To draw the velum upwards, so as to shut the pos- terior nares. PALATO-PHARYNGEUS. OR. The middle of the velum pendulum palati, and from the tendinous expansion of the circumflexor palati. The fibres are collected wiUiin the pos- terior arch behind the amygdalae, and run backwards, to the top and lateral part of the pharynx, where the fibres are scattered, and mix with those of the stylo-pharyngeus. I\. The edge of the upper and back part of the thyroid cartilage, some of its fibres being lost between the membrane of the pharynx and the two inferior constrictors, Us F.. Draws the uvula and velum downwards, and back- wards ; and, at the same time, pulls the thyroid cartilage and pharynx upwards. In swallowing, it thrusts the food from the fauces into the pharynx. N. B, A few of the fibres of this muscle have been called, SAI.PINGO-PHARYNGEUS. And supposed to operate on the mouth of the Eustachian tube. 196 A a re os UVULJE. OR. The extremity of the suture which joins the palate bones. IN. The tip of the uvula. USE. Raises the uvula, and shortens it. MUSCLES ON THE BACK PART OF THE PHARYNX. CONSTRICXTOR PHARYNGIS INFERIOR. OR. t. The side of f he thyroid cartilage ; 2. The cricoid cartilage. This mus- cle is the largest of the three constrictors. IN. It joins with its fellow, on the back of the pharynx; the superior fibres run upwards, and cover part of the mid- file constrictor ; the inferior fibres run more transversely, and surround the oesophagus. USE. To compress the pharynx. CONSTRICTOR PHARYNGIS MEDIUS. OR. The appendix and corim of the os hyoides, and the ligament which connects the os hyoides and the thyroid cartilage ; the fibres of the superior part run upwards, and cover a considerable part of the superior constrictor. IN. The middle of the cuneiform process of the occiput : and it is joined to its fellow at the back of the pharynx. USE. To compress the pharynx, and draw it upwards. CONSTRICTOR PHARYNGIS SUPERIOR. OR. 1. The cunei- form process of the occiput, near the condyloid foramina ; 2.. the pterygoid process of the sphenoid bone ; 3. alveolar pro- cess of the upper jaw ; 4. the lower jaw. IN. A white line, in the middle of the pharynx, where it joins with its fellow, and is covered by the constrictor medius, USE. To compress the upper part of the pharynx, and draw it upwards. TABLE OF THE MUSCLES WHICH ARE FOUND PASSING BETWEEN THE CART1LATES OF THE LARYNX. CRICO-ARYT^NOIDETJS POSTICUS. OR. Fleshy, from the back part of the cricoid cartilage. IN. The posterior part of the base of the arytaenoid carti- lage. USE. To open the rima glottidis a little, and, by pulling back the aryteenoid cartilage, to stretch the ligament, so &s to make it tense. , I 197 LATERALTS. OR. From the cricoid ^ rtilajre, laterally, where it is covered by part of the thyroid. IN. Tile side of the base of the arytsenoid cartilage, near the former. USE. To open the rirna glottidis, by pulling the ligament? from each other. ARYTNOIDEUS TRA.NSVFRSTJS. P-^ses from the side of one arytsnoid cartilage, (its origin oxronding from near its articulation, with the cricoid, to near its tip,, towards the oth- er arytsenoid cartilage. USE. To shut the rima glottidis, by bringing these two cartilages, with their ligaments, nearer to one another. ART.^NOIDEUS OBLTQUUS. OR. The base of one arytae- noid cartilage ; crosses its fellow. IN. Near the tip of the other aryt?enoid cartilage. USE. When both act, they pull the arytaenoicl cartilage towards each other. Very often, one of these is wanting. THYREO ARYT^NOIDEUS. OR. The under and back part of the thyroid cartilage. IN. The arytaenoid cartilage, higher up and farther for- wards than the crico lateralis. AHYT^NO-EPIOLOTTIDEUS. Consisting of a few fibres. Oa. From the side of the arytsenoid cartiiage. IN. The epiglotis. USK, To pull down the epiglottis on the glottis. THYREO-EPIGLOTTIDEUS. OR. The thyroid cartilage. IN. The side of the epiglottis. USE, To expand the epiglottis. N. B. The crico thyroideus is described with those of the throat. 198 DISSECTION OF THE MUSCLES ON THE FORE PART OF THE CHEST. The first muscle which is to be dissected, is the Pectoralis Major. After the fibres have been made tense, by extend- ing the arm and throwing it out from the body, an incision is to be carried through the skin, from opposite to the union be- twoen the bone and cartilage of the fifth rib, to the inside of the arm, at about a hand's breadth below the shoulder. The muscle may be then easily exposed, by dissecting in the line of the fibres, and by carrying the skin first towards the lower part of the chest, and then towards the clavicle ; but we must rsc jllect, that the course of the fibres changes a little as we approach the clavicle. Upon the lower edge of the pectoralis, we shall see part of Serratus Major Jlntlcus. The fibres of this muscle are more difficult to dissect than those of the pectoralis, because their course changes according to the ribs from which they arise ; in consequence of this we shall not be able to make long in- cisions, as we could in dissecting the last muscle, but we must carry the knife in a sweeping direction along each por- tion. In tracing the fibres towards their origin, we shall see the slips of the obliquus externus, with which they indigi- tate ; but we shall not yet be able to follow the muscle to its insertion. Before the insertion of the serratus can be shown, several muscles must be partially dissected, particularly the Latissi,- mm Dorsi, the margin of which will be found running across tire axilla ; this portion of the latissimus should be exposed as far as i'ts insertion into the humerus, and when this is done,. we shall see that the upper and lower boundaries of the axilla are formed by the pectoralis major and the latissi- mus dorsi. A large quantity of fat and glands will be seen between the two muscles, and also many vessels and nerves, which v though they are very important, may be cut away in the pre- sent dissection. 199 Before tracing the lafjssimus' dorsi, or serratus magnus, farthcU' b xck wo should dissect upor; the l^we- edge of the pectoral!^ mr.ij .)*, so as to expose the margin of the Pectoralis Minor, or Serratm .Minor Jl-rdicus. After p, small portion of this is shown, we should raise the pectorahe major This may be done by cutting its origins from the cartilages of the ribs, and by then carrying it towards the sternum, from which it is also to be separated, as far as to the clavicle. In doing this, we should keep all the cellular membrane attached to its lower surface, by which we shall at once clean the surface of the pectoralis minor, and at the same time show a considera- ble part of the serratus magnus. The lattissimus dorsi may now be followed towards the back part of the chest, and by then removing the fat, &c. from its inner surface, we shall expose the edges of the Sub- scapularis and Teres Major muscles. These muscles are not yet to be followed to their insertions, but by making their bellies distinct, we shall expose the insertion of the ser- ratus magnus into the base of the scapula. The whole of the pectoralis major may now be cut away, except a small portion, which should be left attached to the deltoid ; this will enable us to see the Subclavius, which runs from the first rib to the clavicle. If we cut through the pectoralis minor, we shall have an opportunity of seeing the two sets of Intercostal Muscles ; for both layers are found in the middle of the chest, the Exter- nal being deficient on the anterior, and the internal on the posterior part of the ckest. The muscle ' which is called Triangularis Sterni cannot be seen until the sternum and the cartilages of the ribs are re- moved. The muscle will then be apparent on the inside of the sternum, without any dissection being necessary to show its fibres. TABLE OF THE MUSCLES SITUATED ON THE FORE PART OF THE CHEST. PECTORALIS MAJOR. OR. 1. The cartilages and bodies of the fifth, sixth and seventh ribs ; here it intermixes with the external oblique muscle of the abdomen ; 2. almost 'the whole length of the sternum ; 3. the anterior half of the clavicle. IN. Outside of the groove for lodging the tendon of tha long head of the biceps. The tendon is twisted before it is inserted. 200 USE. Tt5 move the arm- forwards, or to draw it down, or to draw it towards the side. SERRATUS MAGNUS, or ANTICUS. OR. The nine superior ribs, by digitations, which, resembling the teeth of a saw, the anatomist calls them serrated origins. IN. The whole base of the scapula, internally, between the insertion of the rhomboid and the origin of the subscap- ularis muscles ; it is, in a manner, folded about the two an- gles of the scapula. USE. To roll the scapula, and raise the arm. PECTORALIS MINOR. OR. The upper edge of the second, third and fourth ; or the third, fourth and fifth ribs, near their cartilages. IN. The coracoid process of the scapula. USE. To bring the scapula forwards and downwards, or to raise the ribs wjben the shoulder is fixed. SUBCLAVIUS. OR. The cartilage that joins the first rib to the sternum. IN. Extensively into the lower part of the clavicle. USE. To pull the clavicle downwards. INTERCOSTALE.S EXTTCRNT. OR. The inferior edge of. the rib, the whole length from the spine to near the joining ef the ribs with their cartilages. (From this to the sternum, there is only a thin membrane covering the internal intercos- tal muscle.) IN. The upper obtuse edge of the rib below, as far back as the spine. INTERCOSTALES JNTFRNI. OH. Like the external muscle ; the fibres run down, and obliquely backwards. IN. Into the margin of the rib below. (From the sternum to the angle? of the ribs.) TRIANGUT.ARTS STFRNI. OR. Frcm the posterior surface ,nd lateral edges of the sternum, and from the en.siibrm car- tilage - I-N. Into the posterior surfaces of the cartilages of tfce d, fourth, fifth and sixth ribs. 201 DISSECTION OF THE PARTS WITHIN THE THORAX. When the muscles are removed from the fore part, the sliest will appear of a eonicle shape, for each rib in succession from the first, forms the segment of a larger circle. We shall now see that it is the projection of the bones and mus- cles of the shoulder, which gives the appearance of breadth to the upper part of the thorax ; and this view will also ex- plain how it may be supposed that a'woimd has penetrated the chest, when it has only passed under the shoulder. There are several modes of opening the thorax. The fol- lowing method will be found useful, when we wish to ac- quire a general idea of its contents, and are not anxious to preserve the bones or the small arteries. The middle of the cartilages of all the seven superior ribs, except the first, are to be cut through with the knife ;* tin- bony parts of the some ribs are then to be sawed through at a point near to their angles, taking care not to encroach up- on any of the muscles of the back, except the latissimus dorsi. The intermediate portions of the ribs may then be remov- ed ; the sternum will remain supported in its natural posi- tion, by its union to the first rib and clavicle above, and to the remaining ribs below. We shall now see that the cavity of the thorax is divided into distinct pares, which are separated from each other by the septum, which is called Mediastinum. The lungs will be seen lying, collapsed, in each cavity ; but this is not the sit- uation in which they would be, in a state of health, in the living body, for, as there is then a complete vacuum in thf chest, the lungs would be distended with air, so as to fill it accurately. The heart, covered with its pericardium, will be seen protruding- its apex to the left side. If there has been no disease in the chest, the serous mem- brane, which is called Pleura, and which covers the lungs, and lines the inside of the ribs and diaphragm, will appear of a glistening colour. It is difficult for a student who studies * We shall be generally obliged to use a saw, to cut through the cartilages of a person above the age of forty. 202 anatomy from books only, to comprehend the folds and du- plicatures of this membrane ; for he is told, that it forms the Pleura Pulmonalis, Pleura Costalis, and ^Mediastinum. But, on examination of the body, he will find, that these terms are used, only to denote the several portions of the membrane. Perhaps the following mode of tracing the pleura will be ex- planatory of its folds, from the septum of the two ventricles ; from which they arise by separate pillars. And again, from the back part of the ventricle, there is a strong column, having a double origin from the two opposite sides of the ventricle, and to which the great posterior division of the membraneous valve is attach- ed. By the attachment of these three divisions to the ten- dinous circle which surrounds the opening between the auri- cle and ventricle, the tricuspid valve is formed. The smoothness of the ventricle towards the opening in- to the pulmonic artery, maybe observed. When the pulmo- nic artery is slit up, its three semilunar valves will be seen. These valves are more frequently perforated in the edges. than -those of the aorta. Ox OPKMISG THE I.F.FT SIDE OF THE HEART. - the blade of the scissors into one of the pulnionic veins, and,. insinuating it into the part of the auricle which projects by the sides of the pulmonic artery, slit it up. There is little to be observed in this auricle : the JiJusculi fectinati not so strong, nor so evident upon its inside., as those of the right auricle. The Puhnonic Veins pass almost always into the cavity by four openings ; those from the right lung are closer together than the left branches. To expose the left ventricle, make an incision as far to- wards >he left side of the artery and vein which rundown from the left auricle towards the apex- as the incision made to lay open the right ventricle was to the right of these ves- sels. In opening this ventricle, there is less fear of cutting upon the columns; carnete, or upon the septum ; fur, as the right ventricle is open, the septum can be seen,, and we can cut immediately on the other side of it ; while the columns? are collected in the further side- of the ventricle, round the opening of the auricle, and are not much exposed to the knife. Continuing the upper part of the incision round un- der the projecting auricle, slit up the aorta, to show its valves : in doing which, that branch of the left coronary ar- tery which comes out under the margin of the left auricle, must be cut through. When this ventricle is laid open, that part which id towards the septum, and more particularly near the artery, w r ill not appear rugged with the interlacements of the columns carnese, or lacerti, as they are sometimes cal- ed. The columns which are connected with the mitral valve, are thick and short, and confined in a corner of the ventricle ; nor do they spread their roots so extensively as those of the right ventricle. Turning our attention to the? semilunar, or sigmoid valves we may observe, in the child,, that they arc 211 loosely floating 1 membranes, variegated in part by a \\ opacity ; while their edges are at some places so transpa- rent , that there appears often be deficiencies of the valve near the edge, when there are none. There are, however, such deficiencies sometimes. In the adult, these valves ac- quire greater firmness and strength, and are opaque ; and there is always on the middle of each valve, a little body. Vv'hich is called Corpus Sesamoideum, or Corpus Aurantii. Behind each of these valves are seen the Lesser Sinuses of fie Aorta, or, as they are sometimes called, Sinuses ofjlfor- gagni ; here the coronary arteries will be seen to arise. When the heart of the foetus is examined, we shall find that it differs very essentially from that of the adult. If we lay open the two auricles, we shall see an oval hole (Foramen Ovale) in the septum, which in the adult separates the one auricle from the other. The ventricles are nearly the same as in the adult ; but from the pulmonary artery, a very large ves- sel passes directly to the aorta. This vessel is called Ductus Jirteriosus. In the adult, it is found degenerated into a lig- ament, which is called the remains of the ductus arteriosus. The minute structure of the walls of the ventricles maybe more easily shown, by plunging the heart into boiling water, for then v/e may easily strip off the pericardium from the sur- face, so as to exhibit the different orders of muscular fibres which compose it. Part of the aorta should be kept for the examination of the coats of an artery. About an inch of it may be distended with a piece of candle or bougie, and another portion may be laid open : in the distended portion we may show the coats, beginning a.t the external, in the other portion, the internal may be shown first. There are generally only three coats described in an arte- ry, but we may enumerate a fourth, by calling the cellular membrane which is between the muscular and internal coat, a distinct one. The three proper coats are, the first Cellular, Vascular, or Tendinous Coat ; the next is the J\Juscular Coat ; and the third the Internal. The outer cellular coat of an artery may be separated into many layers ; easily into three layers. These layers are gradually, as they proceed inwards, changed in their nature from that of the general investing cellular membrane by which the vessel is connected to the parts with which it is in Contact; they are at least incorporated into a more regular 'oat, whence this has been called the tendinous coat ; for it is dense, white and elastic, and has much more toughness than the inner .coats ; but while the inner surface of this, layer, viz* 212 that which is contiguous to the muscular coat, is more accu- rately defined, its outer surface seeming imperceptibly to de- generate into the nature of cellular substance whence it has been described as a cellular cwtt ; but it ha also been called the vascular coat, because the email arteries which ramify upon the larger trunks of arteries, (the Vam T r aso- rum,) run chiefly in it. These arteries are not, in general, der ved from the large vessels on which they lie, but come from some of the smaller branches of arteries. They are, to the great arteries, what the coronary arteries are to the heart. They supply and nourish the coats of the arteries , while the column of blood in their cavities seems to have no such effect. To prepare these subordinate vessels, they must be injected minutely (before the artery is removed from the body) with size, or fine varnish injection, of a light cole ur, or of pure white. If, after this minute injection, a cc arser and dark coloured injection be thrown into the trunks, the light coloured and fine injection will be pushed onward, while the coarse injection fills only the trunks ; making- thus a contrast between the lavge vessels and the ramifications of the vasa vasorum, upcn its surface. The artery, when thus injected and prepared, may be. dried and varnished, or pre- serv ed in spirits. THF, MUSCULAR COAT. Raving dissected these cuter layers, the muscular coat appears. Its fibres run in circles round the artery ; no fibres run in tfce length cf the artery. The circular fibres of the muscular coat do not all pass rcund die artery. On attempting to trace any single fibre, it may be found to make a complete circle round the artery ; but, on further examination, the circle w Tracks- lo Jtfastqideus; or, sometimes, from their intricacy, the corn- plexus minor. We shall now have a distinct view of the proper Complex- us, which is a very large muscle. That part of it which is near to the spine, has a central tendon, whence this portion has sometimes been described as a separate muscle, under the name of Biventer. After showing the numerous attach- ments of the complexus, it is to be raised from the spinous processes, and from the occiput. The Semi-Spinalis Colli will now be seen lying close upon the vertebra? ; and there will also be a set of small mnscles exposed, which run be- tween the vertebra dentata, the atlas, and the occiput. The one which runs from the spinous process of the dentata to the occiput, is the Rectus Capitis Posticus Major ; while the one which runs from the same point, to the transverse pro- 228 cess of the atlas, is the Obli-quus Capitis Inferior ; and from this transverse process, a set of fibres may be traced to the occiput, forming the muscle called Obliquus Capitis Superior. The last of these muscles is a very short one, which arises from the knob on the back part of the atlas, and is inserted into the edge of the foramen magnum ; it is the Rectus Capi- tis Minor. It is not necessary to give any directions for the dissection of the remaining muscles on the back. It only requires that their origins and insertions should be shown, according to the description given in the annexed table. There are still certain muscles which are connected with the spine and ribs, that have not yet been described, viz. those upon the fore and lateral parts of the neck. Directly on the fore part of the neck, there is on each side a long and thin muscle, which is called Longus Co//?. This is sometimes divided into an upper and lower portion : the upper portion runs obliquely from the transverse processes of the third, fourth and fifth cervical vertebrae, to the atlas ; while the inferior portion runs longitudinally from the bodies of the three upper dorsal vertebrae to the bodies of the six lower cervical vertebrae. This lower portion is often de- stroyed, by the vertebrae having been broken by turning the body in the course of the dissection. Upon the outer part of the upper portion, there is a small muscle, which runs from the transverse processes of the third, fourth, fifth and sixth cervical vertebrae, to the basilar process of the occipital bone ; it is the Rectus Anticus Ma- jor : the Rectus Anticus Minor being a very small muscle, which rises from the middle of the atlas, and passes to the edge of the condyle of the occiput. This last is often con- founded with another trifling muscle the Rectos Lateralis, which arises from the transverse process ofthe atlas, and is inserted between the condyie of the occiput and the niastoid process. These muscles which have just been described, may be dis- sected before those of the back ; so may also the Scaleni, which are the muscles that run from the transverse process- es of the cervical vertebree to the first arid second rib. These muscles are distinguished from each other by the terms Sea- lenus Anticus i Scalenus Medius, and Scaienus Posticus. We shall have no difficulty in showing the anticus as a distinct muscle, but the medius a,ndposticus are so closely connected, that they are, by many anatomists, described as one muscle. 229 Iti the following table, the muscles are arranged nearly the order in which they should be dissected. TABLE OF THE MUSCLES OF THE BACK. TRAPEZIUS, or CUCULARIS. OR. 1. The protuberai in the middle of the os oecipitis, by a thin membranous t< don, which covers $art of the splenius and complexus m eles ; 2. from the transverse ridge of the occiput, which < tends from the protuberance towards the mastoid process the temporal bone ; 3. from the ligarnentum nuchae : bel this, the muscle is connected with its fellow ; 4. from 1 spinous processes of the two inferior vertebrae of the ne< and from the spinous processes of all the vertebrae of 1 back. IN. 1. The outer half of the clavicle ; 2. the acromio 3. the spine of the scapula. USE. Moves the scapula according to the three differ* directions of its fibres ; for the upper descending fibres m draw it obliquely upwards, the middle, being transvei fibres, directly backwards, and the inferior ascending fib] obliquely downwards and backwards. LATISSIMUS DORSI. OR. 1- The posterior part of t spine of the os ilium ; 2. all the spinous processes of the sacrum and vertebrae of the loins ; 3. the seven infer spines of the vertebrae of the back ; 4. the extremities of t three or four inferior ribs. Tke inferior fibres ascend < liquely, and the superior run transversely over the infer angle of the scapula, towards the axilla, where they are collected. IN. By a strong thin tendon into the inner edge of t groove for lodging the tendon of the long head of the bicej: sometimes into the tendon of the triceps. USE. To pull the arm backwards and downwards, and roll the os humeri. SERRATUS POSTICUS INFERIOR. (Lying under the latis mus dorsi.) OR. In common with that of the latissim dorsi, from the spinous processes of the two inferior ven brae of the back, and from the three superior of the loins. IN. The lower e.dges of the four inferior ribs, by distil fleshy slips. USE. To depress the ribs. RHOMBOIDEUS. This muscle is divided into twoportioi rhoniboideus major and minor. U 230 RHOMBOIDEUS MAJOR. OR. The spinous processes of the five superior vertebrae of the back. IN. The basis of the scapula, below its spine. USE. To draw the scapula obliquely upwards and back- wards. RKOMBOIDEUS MINOR. OR. The spinous processes of the three inferior vertebrae of the neck, and from the ligamentum nuchce. IN. The base of the scapulae, opposite to its spine. USE. To assist the former. LEVATOR SCAPULJE. OR. The transverse processes of the five superior vertebrae of the neck : the slips unite, to form a muscle that runs downwards. IN. Near the superior angle of the scapula. USE. To pull the scapula upwards. SERRATUS POSTICUS SUPERIOR. OR. The spinous pro- cess of the three last vertebrae of the neck, and the two up- permost ojf the back. IN. The second, third, fourth and fifth ribs. USE To elevate the ribs and dilate the thorax. SPLENIUS. OR. 1. The four superior processes of the back ; 2. the five inferior of the neck, adheres to the liga- mentum nuchse. At the third vertebrae of the neck, the sple- nii recede from each other, so that part of the comptaxus mus- cle is seen. IN. 1. The five superior transverse processes of the ver- tebrae of the neck ; 2. the posterior part of the mastoid pro- cess ; 3. the os occipitis. USE. To bring the head 'and upper vertebrae of the neck backwards and laterally, and, when both act, to pull the head directly backwards. That portion which arises from the five inferior spinous processes of the neck, and is inserted into the mastoid pro- cess and os occipitis, is called Splenius Capitis ; and that por- tion which arises from the third and fourth of the back, and is inserted into the five superior transverse processes of the neck, is called Splenius Colti. SACRO LUMBALIS. OR. In common with the longissimus dorsi. IN. All the ribs, where they begin to be curved forwards, by long thin tendons. From Ui3 upper part of the six or eight lower ribs, arise bundles of thin fleshy fibres, which soon terminate in the in- ner side of this muscle, and are named Musculi ad Sacro-Lum~ balem Accessorii. 231 USE. To pull the ribs down, and assist to erect the trunk of the body. LONGISSIMUS DORSI. OR. Tendinous superficially, and fleshy within. 1. From the side, and spines of the os sa- crum ; 2. from the posterior spine of the os ilii ; 3. from all the spinous processes of the loins ; 4. the transverse proces- ses of the vertebrae of the loins. IN. 1. All the transverse processes of the vertebrae of the back, chiefly by small double tendons; 2. by a tendinous and fleshy slip, into the lower edge of all the ribs, except the two inferior, at a little distance from their tubercles. USE. To raise and keep the trunk of the body erect. From the upper part of this muscle, there runs up a round fleshy portion, which joins with the cervicalis descendens. CERVICALIS DESCENDENS. OR. From the upper edge of the four or five superior ribs, and continued from the sacro luinbalis. IN. The fourth, fifth and sixth transverse processes of the vertebra? of the neck, by distinct tendons. USE. To turn the neck obliquely backwards, and to one side. TRANSVERSAT,IS COI.LI. OR. The transverse processes of the five uppermost vertebrae of the back, and continued from the longissimus dorsi. IN. The transverse processes of the cervical vertebrae, from the second to the sixth. TRACHELO MASTOIDEUS. OR. The transverse processes of the three uppermost vertebrae of the back, and from the five lowermost of the neck, by thin tendons. IN. The posterior part of the mastoid process. USE. To assist the complexus ; but it pulls the head more to the side. COMPLEXUS Or. 1. The transverse processes of the se- ven superior vertebrae of the back, and four inferior of the neck ; 2. by a fleshy slip from the spinous process of the first vertebrae ofthe back : from these different origins it runs up- wards, and is every where inter mixed with tendinous fibres. IN. The protuberance of the os occipitis, and transverse line. USE. To draw the head backwards, and to one side, when acting as an individual muscle ; and when both act, to draw the head directly backwards. N. B. The long portion of this muscle that is situated next the spinous processes, lies more loose, and has a roundish ten- don in the middle of it ; for which reason Albinus calls it bi~ venter cervitis, but if this portion should be called biventer, the term " complexus" is quite misapplied to the other por- tion. SEMI-SPINALIS COLLI. OR. The transverse processes of the six uppermost vertebrae of the back : it ascends ob- liquely under the complexus. IN. The spinous processes of all the vertebrae of the neck, except the first and last. USE. To move the neck backwards. RECTUS CAPITUS POSTICUS MAJOR. OR. The spinout process of the second vertebrae of the neck. IN. The os occipitus, near the rectus capitis lateralis, ans4 the insertion of the obliquus capitis superior. USE. To pull the head backwards, and to assist a little i its rotation. RECTUS CAPITIS POSTICUS MINOR. OR. The knob in the back part of the first vertebras of the neck. IN. The os occipitis, near its foramen magnum. USE. To assist the rectus major in moving the head back- wards. OBLIQUUS CAPITIS SUPERIOR. OR. Tthe transverse pro- cess of the first vertebrae of the neck. IN. The os occipitis, near the mastoid process of the tem- poral bone, and under the insertion of the complexus muscle. USE. To draw the head backwards. OBLIQ.UUS CAPITIS INFERIOR. OR. The spinous process of the second vertebrae of the neck. IN. The transverse process of the first vertebrae of the neck. USE. To turn the head, by moving the atlas on the denta- tus. SEMI-SPINALIS DORSI, OR. The transverse processes of the seventh, eighth, ninth and tenth of the vertebrae of the baek. IN. Into the spinous processes of all the vertebrae of the back, above the eighth, and into the two lowermost of the neck. USE. To poise the spine and support the trunk. SPINALIS DORSI. 'Lying betwixt the spine and longissi- mus dorsi.) OR. The spinous processes of the two upper- most vertebrae of the loins, and the three inferior of the back. 233 IN. The apinous processes of the vertebrae of the back, from the second to the ninth. USE. To connect and fix the vertebrae, and to assist in raising- the spine. MULTIFIDUS SPINJE. OR. 1, The spines of the os sacrum; 2. the part of the os ilium where it joins with the sacrum ; 3. the oblique and transverse processes of all the vertebrae of the loins ; 4. the transverse processes of all the vertebrse of the back, and those of the neck, except the three first, by distinct tendons, which soon grow fleshy, and run in an ob- lique direction. IN. Into the spinous processes of all the vertebrae of the loins and back and neck, except the first. USE. To support the spine and trunk. INTERS-FINALES DORSI ET LUMBORUM, and the INTER** TRANSVERSALES DORSI, are rather small tendons than mus- cles, serving- to connect the spinal and transverse processes. INTERTRANSVERSALES LUMBORUM. Are four distinct small bundles of flesh, which fill up the spaces between the transverse processes of the vertebrae of the loins, and serve to draw them towards each other. LEVATORES COSTARUM. Are a set of muscles, each of which arises from the extremity of the transverse process of a dorsal vertebra, and is inserted into the upper border of the lib next to it. MUSCLES SITUATED ON THE FORE PART OP THE VERTEBRAE OF THE NECK. LONGUS COLLI. OR. 1. The bodies of the three superior vertebrae of the back, and lowest of the neck ; 2. from the transverse processes of the third, fourth, fifth, and sixth ver- tebrae of the neck. IN. The fore part of the bodies of all the vertebrae of the neck. USE. To bend the neck forwards or to one side. RECTUS CAPITIS ANTICUS MAJOR. OR. The points of the transverse processes of the third, fourth, fifth, and sixth ver- tebrae of the neck. IN. The cuneiform process of the os .occipitis, a little be- fore the condyloid process. 0s E. To bend the head forwards. 234 RECTUS CAPITIS ANTICUS MINOR. OR. The fore part of the body of the atlas. IN. The root of the condyloid process of the os occipitis. USE. To nod the head forwards. RECTUS CAPITIS LATERALIS. OR. The point of the transverse process of the atlas. IN. The os occipitis, opposite to the foramen stylo-mas- toideum of the temporal bone. USE. To move the head a little to one side. SCALENUS ANTICUS. OR. The transverse processes of the fourth, fifth, and sixth vertebrae of the neck. IN. The upper side of the first rib, near its cartilage. SCALENUS MEDIUS. OR. The transverse processes of all the vertebrae of the neck. (The nerves to the superior extremity, pass between this muscle and the former.) IN. The upper and outer part of the first rib, extending from its root to within the distance of an inch from its carti- lage. SCALENUS POSTICUS. OR. The transverse processes of the fifth and sixth vertebra? of the neck. IN. The upper edge of the second rib, near the spine. These three muscles bend the neck to one side. When the neck is fixed, they elevate the ribs, and dilate the chest. LIGAMENTS OF THE SPINE. The ligaments of the spine should be examined after the muscles are dissected. All the vertebra?, except the two first, (viz. the atlas and dentata,) are connected together, nearly in the same manner. The first set of ligaments to be dissected, are those which may be easily understood, though, from their shortness, it will be difficult to show them, viz. the capsular ligaments, which bind the articulating processes together. As each vertebra has four articulating surfaces, there must be as many eapsular ligaments, viz. two superior, and two inferior ; these will be sufficiently disctinctly seen, when the vertebra? are divided from each other. If we remove the muscles from the anterior part of several of the bodies of the vertebra?, we shall see a dense fascia^ which may be traced down the whole length of the fore part of the spine ; this is the ligament which is called Ligw- m&rtwn Commune AnteriuS) or Fascia Longitudinalis JLnteri 235 or; we may also see between the bodies of the vertebra, the matter which is called Intervertebral Substance, and, co- vering this, cross slips of ligament, which run from the body of one vertebra to the other ; these are the Crucial Liga- ments. By dissecting away the muscles from the back part of a few of the vertebrae, we shall see tendinous ligaments running between the tips of the spinous process ; these are principally found in the vertebrae of tke back and loins, and are called the Funiculi Ligam'entosi. Between the remaining parts of the spinous processes, an indistinct membranoui ligament may be seen, which is sometimes _ called the Mem- brana Spinosa; and between the transverse processes, from the fifth to the tenth dorsal, we shall find ligaments, that are called Ligamenta Processuum Transversorwn ; but both these, and the membrana spinosa^ are very little more than condensed cellular membrane. All the ligaments which have already been described^ may be found without cutting the vertebrae ; but before we can show the ligaments which are situated more deeply, we must take out two or three of the lower dorsal, or lumbar vertebrae, and cut down the spinal canal, so as to separate the bodies of the vertebras from the processes. Upon the back part of the body, a fascia, or ligament, will be found, corresponding to that which was seen on the fore part ; this is the Ligamentum Commune Posticum, or Fascia Longitudinals Posterior. If we remove the spinal marrow and its sheath from the part of the canal form- ed by the processes, and merely rub the parts with the han- dle of the knife, the ligaments which run from the root of one spinous process to the other, will be exposed ; these liga- ments have, in their fresh state, a yellowish appearance, whence the name of Ligamenta Subflava has been given to them, and, from their course, the words Crurwn Processu- um Spinosorum, are generally added. The ligaments which are common to almost all the verte- brae, may now be enumerated. BEFORE THE VERTEBRAE ARE CUT. 1. Ligamenta Capsularia. 2. Intervertebralia Cartilaginea. [Intervertebral substance*) &, Crucialia. 4. Ligamentum Commune Anterius, or Fascia Longitu- dinalis Anterior. 5. Funiculi Ligamentosi, or Ligamenta Apicinm cessuwn Spinosorum. 236 6. Jlfembrana inter Spinalis. 7. Ligamenta Procesmum Transversorwm* WHEN THE SECTION OF THE VERTEBRJE IS MADE. 1. Ligamentum Commune Posterius, or Fascia Lon~ gitudinalis Posterior. 2. Ligamenta Subflava Crurum Processuum Spinosorum. The connection between the occipit, atlas, and dentata. is very different from the other parts of the spine. The cap- sular ligaments between the atlas and dentata, are looser than between any of the other vertebrae, there is no inter- vertebral substance between them ; but the fascia longitudi- nalis anterior is so much stronger at the middle, that it al- most forms a distinct ligament. The atlas it attached to the occiput, by distinct capsidar ligaments, surrounding each condyle ; and there is also a ligament which surrounds the foramen magnum, and is connected to the upper margin of the atlas, which, as it has, on its internal aspect, some re- semblance to a funnel, was called by Winslow, the Ligamen- tum Infundibi/iforme. The middle of this ligament is strengthened, on the anterior part, by a continuation of the fascia Ion gitudinalis anterior, and on the posterior part, by a ligament something similar to the funiculi ligamentosi. All these connections may be seen by merely dissecting away the muscular fibres which cover them ; but to see the deep ligaments, the bones must be cut in a certain man- ner. As it is supposed that the brain, &c. have already been examined, we should cut through the spine, at the fifth cer- vical vertebrae, and then cut through the vertebrae longitu- dinally, leaving only the ' transverse processes attached to their bodies. We should then carry the saw in the same line, so as to cut through the occipital bone, immediately posterior to the condyles : as this cut will also go through part of the temporal bones, we must take care to keep to the posterior part of the mastoid processes, that we may not destroy the joint of the jaw. The first thing which we have to observe, is the firm at- tachment of the dura mater to the edge of the foramen mag^ num, and to the upper cervical vertebrae. When we tear off the dura mater, we shall see below it, a set of Hgamen- tous bands, which run from the edge of the foramen rnag- num, are then connected to the upper vertebrse, and appear to terminate about the third or fourth ; these bands form the the Apparatus Ligamentosus. We can now feel the proceg- 237 fttts dentatCrs ; and by dissecting away some of the apparatus tigamentows, we shall see two portions of ligament, which arise from the front and sides of the process, and proceed upwards, diverging a little, to be attached to the edge of the foramen magnum : these are generally called Ligamenta La- ter alia, or mod eratoria: for that which has been described as a, Perpendicular Ligament, is nothing more than a few slips of membrane which maybe found between these two lateral ligaments. J5ut the principal ligament here, is that which runs across between the two tubercles on the inside of the atlas ; it is called Ligamentum Transversaie, and locks in the processus dentatus. The Appendices of this ligament are merely its edges, extending upwards and downwards. The corresponding surfaces of the processus dentatus, and of the atlas, are connected together by a very fine capsular liga- ment. There is some difficulty in showing these ligaments dis- tinctly. The dissection will be facilitated by twisting the vertebr round ; for then the ligaments will be easily dis- tinguished from the cellular membrane which covers them^ by the resistance which they offer. LIGAMENTS BETWEEN THE ATLAS AND OCCIPUT. 1. Ligamentum Infundibiliforme. 2. Ligamenta Capsularia. 3. Apparatus Ligamentosus, BETWEEN THE DENTATA AND OCCIPUT.. 1. Ligamenta Lateralia. 2. Ligamentum Perpendiculare. BETWEEN THE ATLAS AND DENTATA, 1. Ligamenta Capsularia. 2. Ligamentum Transfer sate. 3. Capsulare (of the process.) LIGAMENTS OF THE JAW BONE. When the muscles are dissected away from below tfee jaw, the fascia which connects the styloid process to the- jaw, being necessarily cut through, the joint will be much weakened. To understand the structure of this joint, we should com- pare it with those of the carnivorous and graminivorous ani- mals. In the carnivorous animal, as, for example, ia the 238 badger, the jaw bone is locked into the gleneid cavity, s that it is purely a simple hinge joint; and there are only short lateral ligaments. In the graminivorous animal the ca- vity in the temporal bone is so shallow, that much lateral motion is allowed ; and the lateral ligaments are long. The joint in the human bo.dy is of an intermediate form ; for the jaw bone is not so nicely adapted to the hollows in the tem- poral bone, nor are the ligaments so short as in the carniv- orous animal ; but the cavity is deeper, aud the condyle is rounder, than in the graminivorous animal. In the dissection of the external part of the joint, we shall find a ligament running from the lower margin of the zygo- matic process, this may be divided into two portions, one of which runs perpendicularly to the neck, the other to the condyle of the jaw ; it is called Ligamentum Laterale Exter- num. When we look on the inside, we shall see a ligament ri- sing from the edge of the glenoid fissure, and the Eustochian tube, and running to the jaw bone, midway between the an- gle and the condyle ; this is the Ligamentum Laterale Jnter- num. Both of these ligaments are intimately connected with the Ligamentum Capsufare, which arises from the edge of the glenoid cavity, and is attached to the neck of the bone. When we cut through the capsular ligament, we shall find that the interior of the joint is divided into two parts, by an interarticular cartilage, to the edges of which the capsu- lar ligament is attached. LIGAMENTS OF THE RIBS. The ligaments which attach the ribs to the spine, are very simple. We may cut out three of the middle vertebrae, with their corresponding ribs, and then cut through the ribs, so as to leave only about three inches attached to the spine. When the pleura is torn off, the head of each rib will be seen to be articulated with the intervertebral substance of two vertebrse. From the head of each rib, we shall see ligamen- tous bands running to the body of each vertebra, which are called Ligamenta Capitelli Costantm (sometimes called Lig- amenta Antica.) If we cut/through these ligaments, we shall find that the two articulating surfaces on the head of the rib, are attached, by separate Capsular ligaments, to the two vertebrae : the back part of the rib is also articulated with the transverse process, by a distinct Capsular ligament. From the back part of the transverse process, a ligament will be found running to the tubercle of the rib ; this is called 239 the Ligamentum Transversale Extemum. If we forcibly se- parate the ribs from each other, we shall discover two other ligaments, which come from the transverse processes of the vertebrae, and are attached to the neck of the rib. The one which is on the inside, and which comes from the lower part of the transverse process of the vertebra, and is attached to the neck of the rib. immediately below it, is the Ligamtntum Cervicis Costaz Intefnum. The other is on the back part : it arises from the root of the transverse? process, crosses the firsthand is inserted into the upper edge of the neck of the rib ; it is called the Ligamentum Cervicis Costcc Externum.* MGAMENTS BETWEEN EACH RIB AND THE SPINE. 1 . Ligamentum Capitelli Costce, or Ligamentum Ante- terius. %. Ligamenta Capsularia Capitelli^ 3. Ligamentum Capsulare. (Of the union with the transverse process.) 4. Tranwersaie Externum. 5. ; Cermcis Inter num. 6. -Externum. The cartilages of the seven true ribs, are united to the sternum in a simple manner ; and to show the connection, very little dissection is necessary. The sternal extremities of the bony part of the rib being concave, receive the ends of the cartilages, which are convex ; the other extremity of each cartilage isimplanted into the concavities on the lateral part of the sternum. Surrounding each of these points of union, there are capsular ligaments ; and the union to the sternum is strengthened by slips of ligament, running' from the rib, upon the sternum ; these slips have been named according to the direction they run ; those running immediately from the rib to the sternum, are called Ligamenta Radiatim Disjecta ; and some slips, which cross from the cartilage of the one side to that of the other, are called Ligamenta Transversalia. Between the' first rib and the sternum, the union by carti- lage is very complete. The cartilages of the 6th, 7th, 8th, and 9th, are connected by loose capsular ligaments, and by ligamentous slips, which are extended between them, to keep them in their proper position. * When the bones are examined, it is evident that the lig- aments of the 1st, llth, and twelfth ribs must be different from the others, since they are each connected with one ver- tebra only. There is no articulation between the two last and the transverse processes. 240 LIGAMENTS BETWEEN THE CLAVICLES STER- NUM, AND THE FIRST RIB OF EACH SIDE. The sternum should be cut through the middle ; the clavi- cles and first ribs should also be cut, about the middle. The first ligament we perceive, is that running between the heads of the two clavicles, across the sternum ; it is cal- led Ligamentum Interclaviculare. There may then be observed, slips of ligament running from the heads of the clavicle, upon the sternum ; those on the external part, form the Ligamenta Ante^ia ; and on the internal part, the Ligamenta Postica. Under these slips, there is a capsular ligament ; but before examining this par- ticularly, we should attend to the connexion which there is between the clavicle and the first rib. Between the upper part of the rib, and the tubercle on the lower part of the cla- vicle, close to its connexion with the sternum, a strong liga- ment will be seen, which, from its shape, is called Ligamen- tum Rhomboideus. The capsular ligament between the clavicle and sternum, may now be opened ; and then there will be seen an interar- ticufar cartilage, which is connected to the sternum and cla- vicle, by portions of the capsular ligament, so that the cap- eular ligament may be described here, as in the jaw, as com- posed of two parts. DISSECTION OF THE ARTERIES AND VEINS OF THE CHEST, NECK AND HEAD. THERE is no part more important to the student, than the aurgical anatomy of these vessels ; but he must restrain his impatience, and be content, m the first dissection, to learn thek branches Ml The injection of the vessels of the upper part of an adult, or old body, is generally made in the following- manner : An incision is to be carried, through the skin, in the length of the sternum; the bone is then to be cut through, in the same line ; and the chest is to be forcibly opened, by pul- ling on the two portions of the sternum. A piece of wood, about four or five inches long, is then to be placed between them. The pericardium is to be opened : and a large pipe (around which a little cloth must be wrapped) is to be put into the aorta, just at its origin from the ventricle. The de- scending aorta must be tied, about opposite to the fifth dor- sal vertebra. It will easily be found, by tearing up the ad- hesions of the left lung. When an injection is made, with the arteries prepared in this manner, only the vessels of the head and arms, will be filled. Though this is not so good a method as the follow- ing, to^enable us to show the origins of the vessels from the aorta ; still we are generally obliged to do it, if the body is old, or if the aorta is very much dilated. But when the sub- ject is young, and when we are not anxious to preserve the muscles on the side of the chest, the thorax may be so open- ed, that a pipe may be put into the aorta, opposite to the sixth dorsal vertebra. The injection must, in this case, be prevented from distending the ventricle, by an assistant hol- ding the root of the aorta ; for the valves will very seldom prevent the wax from passing into the ventricle. If the in- jection be allowed to pass into the heart, the force, of the syringe will be so taken off, that the extreme branches of the head and arms will not be filled. The manner of inject- ing the heart, &c. for a preparation, has been already des- cribed at page 221. If the student wishes to make a very minute injection of wax, of the arteries of the head or arm, he must inject each part separately ; for when they are both injected at once from the aorta, the extreme branches are very seldom filled. In describing the manner of dissecting the great arteries, I shall suppose that the injection has been made from the aorta, opposite to the sixth rib. Though the ventricle has not been filled, the coronary ar- teries will ; there is not much dissection required to show them, unless the heart be very fat; and in such a case, part of the fat should be removed.* * The dissection of the arteries of the brain should be made, previous to tracing any of the arteries of the chest ; by which the student will have an opportunity of seeing- tiie parts of the brain, which he in all probability would lose, if W 242 By raising the pericardium, and the cellular membrane, from the root of the aorta, the ascending part of the Arch will be exposed ; and by cutting- a little higher, the great vessels which pass from it, would be seen ; but before this is done, we may examine some of the other vessels of the heart, which, though uninjected, may still be easily dissected. First, we may show the origin of the Pulmonary Artery, which, as it runs under the aorta, divides into two great branches, which pass into the lungs. The adhesion which is so strong between the lower part of the aorta., and the point of the bif- urcation of the pulmonary artery, is produced by the remains of the Ductus Anteriosus. On the right side of the ascending aorta, the Descending' Vena Cava is seen ; and when the pericardium is completely dissected away, the great veins which form it, will be shown, viz. the union of the Ltft Jugular, and Left Subclavian Veins* which form a branch, that passes across, to unite with the Right Subclavian, and Right Jugalar Veins. The Vena Azygos passes into the cava, after it has been formed by the union of the great branches. Though the lesser veins are not of much importance, and though they will scarcely be seen, unless they are injected or very much distended with blood, still I shall enumerate them. The Vena Jlfammaria Internet of the light side, joins the upper part of the superior vena cava ; that of the left side joins the subclavian vein, opposite to the cartilage of the first rib. The Diaphragmatica Superior, or Pericardio-Di- aphragmatim, on the right side, joins the upper part of the vena cava ; the left joins the subclavian, below the mamma- ria. The Thymica, on the right side, sometimes joins the right side, enters the root of the subclavian vein : on the left side, it joins the subclavian vein, or the diaphragmatica, or the mammaria interna. The Thyroid Vein, or Trachealis, or Gutturalis of the right side, passes into the upper part of the vena cava : of the left side, into the upper and back part of the left subclavian. The distribution of these veins is he were to leave the dissection of the branches of the inter- nal carotid, until he has finished those of the chest, and of the external carotid. The manner of dissecting the arteries of the brain, is described a little farther on. *The thoracic duct will not be seen unless it has been filled from below, it passes into the angle between the subclaviaw and jugular veins of the left side. 243 described by their names. It is for the most part very regu- lar ; but their communications with the larger veins are ve- ry inconstant, and differ in each side as the great trunks are different. The dissection of the arteries is now to be continued.- When the whole of the pericardium is removed, the arch of the Aorta will be seen, and arising from it, the Arteria Innom- iniltfy the Left Carotid and the Left Subdavian. Before these arteries are traced, the left lung may be pulled up, so that the Descending Aorta may be seen ; but we should not as yet cut away any of the ribs, to show the small vessels which arise from this part of the aorta. After making these trunks distinct, we should dissect the origins of the sterno cleido mastoideus ; and upon one side, (disregarding the relative situation of the parts,) cut off two inches of the clavicle, and an inch of the first rib, with a small portion of the sternum. But before we do this, we should look under the sternum for the mamaria interna, and separate it, so that we may preserve it as a detached vessel. After having made these cuts, which of course must be done carefully, a groat many branches will be exposed. The principal ones will be found to come from the subsdlavian ; for if we dissect between the larynx and the sterno cleido mastoideus muscle, we shall .find that the commojl carotid runs for a considerable distance before it gives off any branch- es. The dissection of the branches from the subclavian must, therefore, be first attended to. We cannot avoid seeing the Jffammaria Internet,, which passes down on the inside of the sternum ; and if we look im- mediately opposite to it, we shall find the Vertebral rising from the upper part of the artery. These two branches are very regular ; but all the others are so much the reverse, that the description which I shall now give, will in all proba- bility not correspond with the vessels which are seen in the first dissection. Close by the origin of the mammaria inter- na, we shall probably find a large trunk, which may be tra- ced towards the larynx, and under the carotid ; this will be the Inferior Thyroid. From the same source, and perhaps in union with it, another branch may be seen crossing the upper part of the neck : this last vessel is to be carefully fol- lowed,- for if it is small, it will be distributed on the muscles of the neck only, and be called the TransvcrsalisColli ; but if it be large, it may then be traced over the scapula, and thence be called the Supra Scapularis. Tkere is generally another branch found here, which pai~ 244 *es from the same trunk, in the clavicle. It is called the Transversali^ Hwneri. As these vessels are very irregular in their order of coming off from the subclavian, we must, in describing- them, give the name to the branches, and tracing them back, apply it it to the trunk from which they arise. If we now trace the subclavian a little farther, we shall sec some small branches lying upon the scalenus : these some- times arise in a distinct trunk, which is called Cervical is Su- perficmlis, but this is very frequently a branch of the trans- versalis colli : Cervicalis Profunda is the name which is given to the artery that rises from the subclavian, while it is- passing under the scalenus anticus. When the subclavian has passed about half an inch beyond the scalenus anticus, we shall find that if the transversalis colli has been small, that a large branch will be given off at this point, and which, as it passes to the scapula, is called the Scapu/aris, or Dorsalis Scapula?. The student must not call this description incorrect, if he does not find it correspond with the arrangement of the vessels which he discovers in the first body which he dissects, for he will, in the course of his studies, find that the order of the branches of the sub- clavian is exceedingly irregular. The description has hitherto been taken from the left side of the body. The manner in which the small vessels branch off, is not very different in the two sides ; but there is a most material difference in the relative position of the great trunks, on the right and left side : this should be particular- ly noticed in making the surgical dissection. As we have already loosened the attachments of the ster- no cleido muscle, by cutting through the sternum and clavi- cle, we may now lay it a little to one side. We shall then see the great Jugular Vein, lying almost over the artery, and the great nerve, the Par Vaguin^ by the side of it ; but at present we need not attend particu]arly to these parts, but pull them to one side, and then trace the common carotid, with the foreceps and scissars, from its origin, on the left side, from the arch of the aorta. The artery will be found to pass up by the side of the larynx, for three or four inches, without giving off any branch- es : here it is called the Common Carotid. It at once di- vides into two great trunks, which are called the External and Internal Carotids. The internal will afterwards be found to pass to the foramen caroticum of the temporal bone without giving off a branch. Hence all the branches which we have to trace among the muscles of the throat, and on the faoe and temples, mvist be from the external carotid, 245 The first branch which we shall find rising from the Exter- nal C f .:r<>tul* is the Superior Thyroifl this we ir,\\vt trace downwards, tow'rds the thyroid gland, m whirh we hhali find it distributed, and uniting 1 its branches with those of the Inferior Thyroid, which we have already seen coming fr ni the subclavian. The next branch which. is given of, is the Linf^unlis : we may trace this along the line of the cshyoides to the muscles of the tongue, where it divides into several branches : but before we can trace these fully out, we i: i^ ; follow some of those of the next artery, the Faci/.iis, or External Maxillary, This comes off very often in the same trunk with the lingualis, and if not, it rises immediately af- ter it. It runs first towards the lower part of the jaw, and under the muscles. (But as both this and the lingualis are covered by the digastricus 'and stylo hyoideus, it will be neces- sary to make a neat elk-section of the. muscles, before we can trace them farther.) After the facial emerges from under the muscles, it passes into the substance cf the snbmaxillary gland, through which the branches must be carefully traced*: from these, one branch will be seen to pa.^s on the anf part of the mylo hyoideus ; this i- the submentafis. The trunk of the artery, alter pacing through the submaxiliary gland, turns over the jaw, to be distributed upon the face ; but, the branches which pass to the face should not be dissect- ed until some of those below the jaw have been traced. The submaxillary gland should now be rahed ; the lin- gualis may then be traced under the thyreo hyoideus mus- ele, sending its branches among the muscles of tlit -. toinrrr. which can all be easily followed if we have already made ourselves master of the muscles of the tongue. Alter having 1 traced the lingua" artery to <-c me depth, it will be found to divide into two principal branches, which are the arltria dor- sal Is lingvce, running towards the root, and the rfminft, run- ning to the tip of the tongue, I ,-hall not here give ihe names of the smaller branches of the thyroid, facial, and lin- gual, but refer to the next //;/,/>. To prosecute the dissection farther, we should carefully raise the skin from over the outer part of the mnssele: wards the i.ube of the ear, and continue the dissection of rouri ilthe bock of ihe ear, and over the insertion of the .)/V.v- 'ti and Trdppzius. In removing the skin from the iwus- seter, we must take care that, we do not cut the Trunwrsu- />'> Fueled which lies immediately under the skin, and gene- rally in a line with the middle of the tube of the ear. Some small branches of the facial, which are called mawtf \vill also be seen upon the masseter. In removing the ^kin fiorn the back of the ear, we must avoid cutting the branch* 246 we of the Posterior Jluris, which are very superficial. Tiie- lame care is also to be taken in dissecting towards the occi- put, as many of the superficial branches of the Occipital pass ever the Jtfastouleus and Trapezius. The Parotid Gland will now be exposed ; but before we trace the branches through it, we should examine the trunks of those branches which are seen on the occiput and ear. Three arteries generally rise from the carotid, before it enters into the substance of the gland, viz. the Occipital, the Posterior A iris, and the Pk&ryngea Inferior. The occipital arid posterior auris very often come off in one tiunk, and if not. they come close together, and immediately at the outer edge of the digastricus and stylo hyoideus. The posterior auris may be traced first, as it runs superficially towards the back of the ear. The occipital will be found to run so deep under the insertion of the sterno cleido mastoideus, that, to trace it fully, we shall be obliged to dissect through the sub- stance of mis muscle ; we shall then find its branches be- coming superficial, some of which pass to the scalp, and oth- ers run to supply the superficial muscles of the back. The pharyngea inferior is not unfrequently the second branch that arises from the external carotid ; but, as it rises from the back part of the artery, it cannot be conveniently seen until the branches which have already been described, are partially dissected, and even in this stage, its trunk only can be seen : the branches will be seen after those under the jaw are dissected. The trunk of the carotid is now to be traced into the par- otid gland: while here, it gives off a number of small branches, which are to be exposed by carefully cutting away the substance of the gland. The larger branches, which are very superficial, should then be traced, viz. the Tempo- ral and the Transversalis Fwiei. These are so immediately under the skin, that there can be no difficulty in finding them, After exposing these branches, we may return to the dis- section of the arteries of the face, for which there is no farther rule necessary, than merely to follow them from trunk to branch, with the scissors and forceps. -The names of the small branches will be found in the Table. Many of these branches must now be destroyed, that we may show the arteries which pass into the deep parts of the face,* and particularly the branches of the Maxillaris In- * Nearly the same rules should be followed in making a of the arteries of the heud. The superficial ar- 247 The dissection of the branches of this artery is very diffi- cult ; for we must not only cut through the greater number of the muscles on the side of the face, but we must also re- move the greater part of the jaw. The first thing we should do, is to expose the trunk of the external carotid, until the internal maxillary is seen going off from it, which it generally does, opposite to the lobe of the ear. The artery is then to be traced &s far as possible under the jaw. After which, the jaw bone is to be cut through, just at the point where the facial artery passes over it (in doing this, we should, of course, take care not to in- jure the arteries of the neck.) We may then cut through the insertion of the pterygoidetis interims^ after which, trie knife is to be carried close upon the inside of the bone, so as to separate the buccinator and the membrane of the mouth from it. When this is done, we shall be enabled to pull the jaw aside, so as to enable us to trace the trunk a little far- ther, and perhaps to see its first principal branch, viz. the dental artery, which passes into the lower jaw ; but in a first dissection, this vessel is to be sacrificed,* for the whole of the side of the jaw should be removed ; but to do this safely, and at the same time to enable us to expose all the branches of the maxilaris interim, we must also remove the whole of the os malse, and zygomatic process of the tempo- ral bone. This may be done, by first cutting with the sa\v through the maxillary and frontal process of the os matae, and the root of the zygomatic process ; and then, with a blow of the chisel and hammer, the parts will be so loosened,, that they may be easily dissected off. The insertion of the temporalis should be cut from the coronoid process of the jaw; and by then merely cutting close upon the bone, and using a little force, we may remove the whole of the remain- ing part of the jaw. When the bones are removed, the parts will appear in great confusion, as the arteries are buried in the temporal muscle, and part of the two pterygoid ; but, as \ve have no object now in preserving these muscles, we should trace the branches of the great artery through their substance, with- out fearing to sacrifice their fibres : indeed, to make the teries should be preserved on one side, and on the other., they should be removed, so that the deep ones may be exhi- bited. * In making a preparation, we may preserve the dental ILT tery, by leaving a small portion of the jaw. 248 branches distinct, we shall at last be obliged to cut the mus- cular fibres entirely away. The first branch that comes off from the internal maxilla- ry, is one of little consequence, but the next, L- of the greatest importance, the JWeningea Media, for this is the vessel which supplies the principal part of the dura mater : it may be traced into the foramen spinale of the sphenoid bone. The next set of branches will be found passing through the substance of the pterygoid muscles. We shall then see the stump of the small branch which passes into the spinal hole, to supply the teeth, viz. the dental, or infe- rior marUlary. The'next branch is, the tempo-rails -i>r< fun- da, or media, which passes into the substance of the tempo- ral muscle, and runs close on the bone. The main trunk of the maxillary now becomes so crooked, that we shall be in danger of cutting it through, if we are not very cautious. It will be found lying on the back part of the superior maxillary bone ; and here it gives off some small branches, which are called alveolares superiores, as they pass to the teeth of the upper jaw. The trunk now becomes exceedingly difficult to follow ; for.it passes into the spheno palatino figure. From ihis part o le branch may be traced into the orbit, which we shall afterwards find, passes through the infra orbital canal, with the infra, orbital nerve, to the upper part of the supe- rior maxillary bone, where it inosculates with the branches of the facial; this artery is generally called the Infra Orbi- tal. The next branch is also very "difficult to follow ; for it passes at first directly .downwards, through the palatine fis- sure, into the palatine foramen, from which, it sends i-ne branch back to the velum and a larger to the anterior part of the palate : this last branch, the Pahdina, may be con- sidered as the extremity of the internal maxillary artery. Tnere are, however, still two branches to be enumeratd : first one which creeps by the side of the external pterygoid pr >cr^s, aii-1 is distributed on the upper part of the pharvnx, and. is called the superior p : >ar//n.^eal while another runs into the back oart of the nostril, through the spheuo palatine hole, and is called the nana' : this is distributed on the lower part of the nostrils; and from it, a branch may often be triced., along the lower part, to the foramen incisivum, to inosculate with the palatine. I have been a little more minute in tho description of this artery* than that of the others, for it is one particularly diffi- cult to follow ; indeed, in order to see the branches of it dis- tinctly, we must sacrifice every other pare. The student, while dissecting this artery, should have the basis of the scull 249 constantly before him, to enable him to understand the differ- ent twists of the artery. We should now turn our attention to the internal carotid. This artery will appear, at the bifurcation, to be more exter- nal than the external carotid ; but it almost immediately be- comes more internal^ and passes deep under the parotid gland, and there it is covered by the great nerve, and lies elose upon the rectus capitis anterior. vVe then lose it ; for it passes into the foramen caroticum of the temporal bone. During its whole course, we shall find no branches rising from it, except some very small ones, to the nerves and to the Eustachian tube. The internal carotid must now be followed through the bone. This may be done, and the branches of the maxilla- ris interim be still preserved : but we must entirely change our plan of dissection. If we wish merely to gain a knowledge of the course of the internal carotid, through the brain, we may remove the scull-cap, arid proceed to the dissection of the brain.* It is presumed, that the student has already a general knowledge of the parts of the brain. On raising the scull-cap, which is to be done in the manner recommended for examining the brain, at p. 160, the vessels of the dura mater will be the first that will strike the eye. Those on the part opposite to the frontal bone, may belong to the anler-ivr m&*ing&Lli which rises from the Ophthalndca ; but this artery is so small, that the large vessel, the Meningea Media, which will be seen under the parietal bone, generally gives off all the * T have, in a note at page 241, said, that the dissection of the branches of the internal carotid should be made, before any of the others, in & .first dissection; but if the student wishes to make a preparation of the arteries of the brain, it will be better to delay the dissection of them until all the others are finished, for then, (the brain being putrid,) the branches of the internal carotid may be exposed, by merely washing away the pulpy matter of the brain ; in this in- stance, "the scull should not be opened in the common man- ner, rut a cut should be made through the frontal and parie- tal bones, in the line of the falx, but a little to one side of it. This incision may extend from above the orbit, to the tuber- cle of the occipital bone. Another cut may then be made, above the level of the ear, to meet the two extremities of the first: the intermediate portion of bone is then to be entirely removed. By this, we shall have an opportunity, when the pulpy matter is washed away, of showing the prolongations f the dura mater. 250 branches that are seen in the first view. The meningea me- dia may afterwards be traced back to the foramen spinale of the sphenoid bone through which it comes from the maxil- laris interna. Some small twigs from the posterior mmin- geal may be seen, hut these are seldom apparent, until the tentorium is raised. The dura mater may now be cut through, along the line of the longitudinal sinus, and oh one side only, at present, so that the falx may be left entire. The dura mater i then to be folded over, towards the tem- ple. The vessels on the surface of the brain will now be seen in great numbers ; they arise from several sources, which will be discovered, as the dissection is continued, to- wards the base. The first arteries (which have distinct names) that can be seen, will be those of the corpus callosum ; the artery of each side may be shown, by merely pulling the hemisphere separate from the falx. After taking this view, we may cut the dura mater which covers the opposite hemisphere. We should then separate the falx from its connexion to the crista galli , and throw it backwards towards the tentorium ; and now we can sepa- rate the hemispheres, so as to have a better view of the ar- teries of the corpus callosum. The whole of each hemis- phere is then to be cut down to the level of the corpus callo- sum j for it is needless to attempt to trace the arteries which we see on the surface, down to their trunks, as they form a complete net- work in the substance of the brain, which net- work is supported by the pia marer. We may judge of the number of these vessels, by allowing a stream of water to play upon the mass which has been removed ; for this will wash away the pulp, leaving only the membrane and vessels. By now separating the two anterior lobes, we may trace the arteries of the corpus callosum towards a trunk, which we shall afterwards find to be the Anterior Cerebri. We may then open the ventricles, and we shall see the choroid plexus loaded with the vessels, which are to supply the most inter- nal parts of the brain. We oaust now examine the other brandies, by raising the brain from the scull. In lifting up the anterior lobes, we shall see the optic nerves; and by the side of them, the trunk? of the internal carotids. These must be cut across, but we should leave enough of each artery to show the ori- gin of the Opkthalmica, which passes into the orbit. The several nerves are to be cut through, as we carry the brain back. The tentorium is to be divided, by carrying the knife along the line of the petrous portion pf the temporal bone. 251 The two Vertebral arteries will then be seen,* coming up from the vertebral canal. When these, and the upper part of the spinal marrow are cut through, the whole mass of the brain may be lifted out. The vessels may be seen on the base, without any dissection, but they will be made more dis- tinct, by removing the tunica arachnoides. The enumera- tion which is given in the table will be a sufficient description of them. TABLE OF THE ARTERIES IN THE THORAX, AND OF THE NECK AND HEAD.. AORTA. Anterior to the Arch CORONARIA DEXTRA and CORONARIA IINISTRA. From the Arch INNOMINATA, divided into CAROTIS DEXTRA and SUBCLAVIA DEXTRA : CAROTIS SINISTRA and SUBCLAVIA SIMSTRA. From the descending Aorta a series of small arteries, viz. PERICARPIACA POSTERIOR; PER1CARDIACA INFERIOR; BRON- CHIALIS DEXTRA ; BRONCHIALIS SINISTRA ; CESOPHAGEJE ; IN- TERCOSTALES AORTFCJE. From the SUBCLAVIAN, the principal or primary branches are : I* MAM MARIA INTERN A ; II. TH YROIDE A IN- FERIOR ; III. INTERCOSTAJLIS ; IV. VERTEBRALIS ; V. CER- VICALIS PROFUNDA ; VI. CERVICALIS SuPERFICIALIS. I. MAMMARIA INTERNA gives these branches : -1. Thyroi- dece ; 2. Comes JVervi Phrenici; 3. Pericardiaca ; 4. JWcdiastince ; 5. JMammarice ; 6. Epigastrica Anastor moiica. II. THVROIDEA INFERIOR generally sonds off 1. Transver- salis Humeri ; 2. Transversalis Colli (either this or the * These arteries are very difficult to trace from their ora- gin from the subclavain, as the greater part of their course is through the canal which is formed in the transverse processes of the cervical vertebra. The spaces between the vertebrae should be cleared of the muscles, &c. to allow of the artery being seen ; or the processesses may be cut through. Sev- eral branches will be found passing oft from the artery, in it* passage upwards, which are enumerated in the Talie. We must be careful, in desecting between the atlas and the occi- put, as the artery bulges out so, between these bones, that it. is very liable to be cut. 2-52 last branch gives off the scapulari*, though it is often a principal branch of the subclavian ; it then rises be* low thescalemis;) 3. Thyroidea Ascendens ; 4. Thy- roidea Propria. III. INTERCOSTALIS : its branches pass irregularly to the two superior intercostal spaces, to the scalenus and oeso- phagus. Some branches pass to the muscles of the back. IV. The Fertebralis, principally to the back part of the brain ; but it also gives 1. a class of small branches to the muscles attached to the cervical vertebrse ; 2. to the theca and spinal marrow; 3. to the muscles under the occiput; 4. within the scull, to the dura mater, viz. Meningeaz Posterior es : 5. Inferior Cere- belli ; 6. Spinalis ^Posterior ; 7. Spinalis Anterior. The two vertebral then unite and form the Basilar. From the basilar there are 1. branches to the Me- dulla Oblongata, &c. 2. Prqfunda, or Posterior Cere bri ; 3. Arteriw Communwanies (uniting with those of the carotid, to form the Circle of Willis.) V. CERVICAL is PROFUNDA ; gives branches to the Scaleni and Longus Colli. VI. CERVICALIS SUPERFICIALIS ; passes to the Brachial plexus, Scaleni, Trapezm-s, &c. COMMON CAROTID divides into EXTERNAL and IK TEftNAL ; from the EXTERNAL, the principal branch- es are: I. TKYROIDEA SUPF.RIOH; II. LIJSGUALIS ; III. FACIALIS ; IV. PHARYNGEA ASCENDENS; V. OCCIPITALIS; VI. AURICULAR.IS POSTERIOR ; VII. TEMPORALIS ; VIII. MAX ILL A nis INTERN A.* I* THYROIDEA SUPERIOR gives off: 1. thyroidea propria ; 2. laryngea, to the epiglottis, and muscles of the ary- tenoicfcartOage. Superricialismusculares, viz. to the sternocleido mastoideus, to the sternoliyoidei and thy* roidei, to the thyreo-hyoideus. II. LINGUALIS. 1. Sublingualis ; 2. dorsalis linguae; 3. ranina ; 4. irregularly to the muscles of the tongue and pharynx. f * The arrangement of the branches of the external caro- tid is very simple. We have only to recollect the parts which it passes, and then We shall have the names of the ar- teries. Thus, it passes the tlyroid gland ; the tongue ; the face ; the pharynx ; the occiput ; the ear ; the inside of the jaw, and the temple. f These vessels may be divided into three sets, of compa- 253 1&. FACIALIS. I. Palatina ascendens; 2. to the glands and muscles of the tongue ; 3. to the submaxillary glands and the tonsilaris ; 4. submentalis ; 5. to the masse- ter and buccinator 6. coronaria labii inferioris ; 7. coronaria labii superioris ; l nasalis lateralis ; a an- gularis. IV. PHARYNGEA ASCENDENS. 1. Three internal pharyn- gese ; 2. Three posterior to the muscles, to the sym- pathetic nerve and jugular vein, to the glands; enters the foramen lacerum posterius. V. OCCIPITALIS. 1. To the digastricus, stylo hyoideus, and sterno cleido mastoideus ; 2. meningea, viz. with the jugiilar vein through the foramen; 3. cervicalis de- scendens ; an internal branch inosculates with the vertebralis ; 4. auricularis ; 5. occipitalis ascendens. The foramen mastoideum posterius receives a branch to the dura 'mater. VI. AURICULARIS POSTERIOR. 1. Branches to the parotid gland, biventer, and mastoid muscles ; 2. to the mea- tus extern us, and membrane of the tympanum ; 3. stylomastoidea, entering the tympanum, supplying the parts there and the mastoid cells ; 4. ascending behind the ear to its muscles and cartilages ; 5. as- cending on the temple. VII. TEMPORALIS. 1. A small deep branch, and a branch to the masseter ; 2. transversalis faciei, comes duc- tus saliv : 3. temporalis media profunda ; 4. auricula- res anteriores : 5. temporalis anterior, or frontalis ; 6. temporalis posterior, or occipitalis. VIII. MAXILLARIS INTKRTVA, (being in the order of the branching.) 1. Auricularis, prcfunda and tympani- ca ; 2. meningea media; 3. meningea parva, viz. to the pterygoicl muscles, and finally piercing the foramen ovale ; 4. maxillaris inferior ; 5. temporales profun- dfie maxillares, pterygoideae, and buccales ; 6. alveo- laris ; 7. infra orbftalis; 8. palatina maxillaris: 9. pharyngea superior ; 10. nasalis. rative importance in a surgical point of view. In the rirst set there are, the one to the thyroid gland, that to the tongue and the artery to the face. In the second set, the one to the inside of the jaw, arid those to the temple. The next set is of very little importance, as they lie deep, and are very small ; viz. those to tiie pharynx, occiput, and ear. 254 INTERNAL CAROTID. I. While in its transit through the bones, these branches; to the pterygoid canal and cavity of the tympanium ; to the cavernous sinus and pituitary canal ; to the fourth, fifth, and sixth pairs of nerves ; to the dura mater. (Within the cranium, and having emerged from the dura mater.) II. OPHTHALMICA CEREBRALIS. Passing into the orbit by the foramen opticum, gives these branches : 1. to the dura mater and sinus ; 2. lachrymalis, which goes to the gland,, after giving many branches to the perios- teum, optic nerve, &c. ?. ciliares" three or four ar- teries dignified with the distinction of inferiores, an- teriores, breves, longiorts ; 4. supra erbitalis ; 5. cen- tralis retinae ; 6. ethmoidales ; 7. palpebrales ; 8. na- 'salis ; 9. frontalis. III. SEVERAL LESSER BRANCHES TO THE PITUITARY GLAND, OPTIC NERVE, INFUNDIBULUM, AND PLEXUS CHO- ROIDES. XV. AA. COMMUNICANS. Constituting part of the circle of Willis. V. AA. CEREBRALIS ANTFRIOR. 1. Irregular branches to the first and second pair of nerves : 2. lesser irregular branches to the anterior lobe ; 3. anterior communi- cans (completing the circle of Willis interio/ly) 4. arteria corporis callosi. VI. AA. CEREBRALIS MEDIA. Entering the fossa Silvii ; it is minutely distributed to the substance of the middle lobe. OF THE VEINS OF THE HEAD. The veins of the face and neck may be seen without their being injected; indeed, this should never be done, except when we wish to make a preparation of them. For this purpose, a pipe should be placed in the frontal vein, through which a quantity of warm water should be thrown, so as to clear the superficial veins of their coagula. To distend the deep veins, a pipe should be put into the longitudinal sinus, directed towards the occiput, (a portion of the scull having been previously removed : or they may be filled by putting a pipe into each internal jugular vein. *The success of the in- 255 jection will depend very much on the veins being thoroughly cleared of the blood which is coagulated in them. After they are injected, the dissection will be very easily made ; for the veins are so superficial, that, in a thin body, they will be seen under the skin. The vein which may be traced from the inner angle of the eye, towards the lower jaw, is the Anterior Facial ^ or the Angularis* This vein receives branches from various parts of the face, which are named according to the points from which they come ; as, venafrontalis ; vena ophtlialmica ; ve- na dorsalis nasi, superior et "inferior ; vena alaris nasi ; vence labiales, magnce et minores ; vence buccales, fyc. At the angle of the jaw, the Facial vein will be found to unite with the Temporal, or, as it is sometimes called, the Posterior Facial. By this union, the External Jugular is generally formed. The temporal vein is formed by branches which come from the temple (generally four in number) ; by the veins which accompany the branches of the arteria maxillaris interna ; by the transversals faciei ; the posterior aims ; and some- times, by branches from those accompanying the arteria Hie- niiigea media. The External Jugular will be found to be very irregular ; sometimes it divides into two branches, the one being called the anterior, the other. posterior. The anterior division gen- erally receives the branches under the chin, and from the tongue, and often joins the great internal jugular vein : while the posterior receives some from the occiput and the back part of the ear, and then passes down to thesubclavian, in its course, receiving veins from the outer part of the neck, and upper part of the shoulder. The veins of the thyroid correspond very much with the course of the .arteries ; the superior ones passing into the jug- rJar, and the inferior into the subclavian, or the transverse vein, which passes across the great arteries. The Internal Jugular vein is formed principally by the sinuses of the dura mater, which have already been describ- e 1 at p. 173 : but in its passage down the neck, it generally receives the branches corresponding to the deep arteries. It will be difficult to trace the branches of the Vertebral Veins. The basilar sinus generally passes into them ; they receive, also, the branches from the upper part of the spinal marrow : but they are principally formed by a net- work of veins, which surrounds the processes of the spine, and come from the deep arteries which supply the small muscles of the back. The trunk of the vein passes in the same canal the artery, viz. in the transverse processes, and termir. in. the subclavian vein. 256 DISSECTION OF THE OF THE HEAD JtND NECK. WE may begin either with the dissection of the nerves of the face, which are from the Vth and the Vllth, or with the plexus, which is formed immediately under the skin of the neck, by the superficial branches of the cervical nerves and spinal accessory.* 1 shall suppose that we are to dissect those of the neck first. If we cut through the skin, about opposite to the middle of the sterno cleido raastoideus, we shall find some branches, which, if patiently followed, will lead to all the others. The nerves on the side of the neck are so numerous, that it is im- possible, in a work of this kind, to particularize them all ; but there is one more distinct than the others, which passes from the third cervical, along- the sterno cleido mastoideus muscle, to join the branches of the portio dura. This branch is sometimes called, nervus communicans, or superficialu Colli, When the skin over the parotid is raised, some branches of the Portio Dura, or respiratory nerve, of the face, will be seen. These may be traced into the substance of the parotid gland, by digging with the scissors ; this is to be done, by putting in the blades, closed, and then opening them, by which the portions of the gland will be torn, rather than cut. In following the branches ofthe portio dura upon the face, we should not remove more ofthe skin than the cutis vera* for many ofthe principal branches lie immediately under it ; * In the following description ofthe manner of dissecting the nerves, I shall introduce, in the form of notes, some of those observations which Mr. Bell has been for many years in the habit of making while delivering his. lectures on the nerves ; several of these will be found in the edition of the Plates of the Nerves, published in 1816. I shall only hint at certain experiments which are detailed by Mr. Bell, in, a pa- per in the transactions of the Royal Society for the present year. The new names which have been given to some ofthe nerves, will be underptood by referring to the explanation uf tf> plate*. 257 these will be found, in their course from the interior of the parotid to the different parts of the face, to be united togeth- er by cellular membrane, so as to have some resemblance to the webbed foot of an aquatic bird, whence the name of pes anserinus has been given to the plexus which is formed by them. The three branches, viz. the Supra Orbital, Superior Jftaril- lary, and Inferior Maxillary, of the Vth,* will be easily dis- covered by recollecting the three foramina through which they pass to the face, viz. the Superior Orbital, Infra Orbi- tal, and Mental. After the trunks are exposed, there will be no difficulty in tracing their branches to their terminations, and also to show the intimate connection which each of them has with the branches of the portio dura. The dissection will be most easily made, by tearing the cellular membrane from between the nerves, by using the srissors and a small hook, in the manner already described.! After having seen all the superficial nerves, we may pro- ceed to the dissection of those which lie deeper. The platisma may now be removed, and the external sur- face of the sterno cleido mastoideus be dissected clean ; so may the digastricus superior, and the mylo hyoideus : but we must not take off.all the cellular membrane from the sterno hyoideus and thyroideus muscles, because in doing so, we should cut across some of the branches of the descendant noni. The origins of the sterno cleido mastoideus may now be raised, and the muscle be carried towards its insertion. In doing this, we shall see, at about two inches from the mas- toid process, the Superior Respiratory Nerve, or Spinal Jtr.- cessory,\ entering into its substance, and perforating it, in an oblique direction. After tracing the branches of this nerve, we ..hould cut through the digastricus superior, so as to ex- pose the stylo hyoideus ; immediately below the level of which, we shall discover the IXth, or Lingual Nerce^ run- ning towards the os hyoideus : if we pull upon it, we ^hall see a small branch running down the neck, towards the mus- * See the notes upon the deep dissection of these nerves. f When we have finished the dissection for the day, we should either cover the parts with a wet cloth, or put them into water ; by this, the nerves will be blanched, and after- wards more distinctly seen. If bougies, or black pins, be put under the nerves which have been dissected, the display will be still more distinct. t See note upon this, in the deep dissection. 258 cles on the larynx ; this twig is the descendens rxmi, which, if followed, will be found to pass along the sheath surround- ing- the carotid artery and jugular vein, and to form connec- tions with some of the cervical nerves. It is lost upon the sterno hyoideus and thyroideus muscle.* The trunk of the IXth may be traced a little forward, but not far, as we shall have a better opportunity of seeing it presently. The sheath :of the vessels may now be opened. Immedi- ately between the artery and vein, the groat nerve, the Par Vagum, will be seen : and if we lift up the sheath altogeth- er, we shall find the sympathetic, lying closB upon the mus- cles of the. spine. These nerves may be exposed for a short distance ; but, those below the angle of the jaw, must be dis- sected, before we can show their connections. The first nerves which we should dissect under the jaw, are the three which pass to the tongue. We have already seen the IXth, or Motor Linguce. If we now hold aside the submaxillary gland, and cut care- fully through the mylo hyoideus, we shall seethe Gustatory ; and by lifting up the lobe of the parotid gland, and dissecting along the line of the stylo pharyngeus and glosso pharyngeus muscles, we shall find the Glosso Pharyngeal^ which* is the third nerve of the tongue, f * In the connections of the seventh, the ninth, the nervus &uperficialis, cervicales, the roots of the phrenic, and that which is called the external respiratory, we see the media of many combinations : the expression and consent of parts in sneezing, coughing, vomiting ; the expressive spasmodic actions during violent passion ; the spasms in hydrophobia and tetanus. In the connections of the phrenic nerve with the cervical nerves, we may observe the source of that re- markable sympathy which makes the affection, or wound of the diaphragm, be attended with pain in the shoulders, or convulsive rising and shrugging of the shoulders. f The gustatory nerve connects the salivary glands and muscles of mavstication. The ninth is the nerve of speech, a id connects the tongue with the muscles of the larynx and trachea. The glosso pharyngeai nerve associates the tongue and pharynx in the action of deglutition. We may now comprehend how the tongue, being put into action through the intervention of distinct nerves,, may be deprived of one faculty, and retain the others. Thus, a Sections of the brafh, and sometimes the disorders of the bowels, deprive the pa- tient, at one time of taste, at anoiher of speech 3 or at anot&ei $f swallowing. 259 But to facilitate this part of the dissection, and of the other deep- nerves, the jaw should be cut through at the symphy- sis and at the angle ; and after the membrane ofthe mouth has been separated from the bone, the intermediate portion may be removed. A piece of twine is then to be put thrcugfc the tip of the tongue, by which it nray be pulled out By holding aside the remaining parts of the jaw, fc great nerve will be discovered, emerging from between the two pterygoid muscles ; this is third of the Vth, being the trunk of the Gustatory, and of the Inferior Maxillary. After the inferior maxillary has been traced into the hole in the jaw bone, it should be cut through, and a piece of co- loured thread attached to it, by which we may again recog- nize it. The remaining portion of the jaw may now be re- moved ; but we must be particularly careful in extricating the condyle, or we shall be in danger of cutting a little nerve, \vhich funs backwards from the lower part of the gustatory* just at the point where it separates \ rom the inferior maxil- lary. This small twig will afterwards be found to paes through a little hole by the side of the glenohl cavity > and then to cross the merrlbrana tympani (whence its name of cordatympani ;) it joins the portio dura, but perhaps it will be more proper to describe it as a branch coming from the portio dura, to unite with the Vth.* The jaw being. now entirely removed, we shall have a beautiful exhibition of the nerves of the tongue ; for by merely pulling it out, we may trace the Gustatory to the tip, the lingual to the muscles* and the glosso pharyngeal lo the tongue and pharynx. We may now dissect away the parotid, and also the sty- loid muscles, and ,s many of the branches of the carotid as we can^ without injuring the trunk of the portio dura : this will expose what appears at first a very intricate plexus of nerves, but if we put probes under all those which have been already described, we shall find the intricacy to be very much unravelled. If we look towards the tongue, we shall aee the Lingual Gktstatory, and Glosso Pharyngeal ; and to- wards the back of the ear, the Portio Dura and Spinal Ac- cessory ; and downwards, the Par Vagicm and Sympathetic. These nerves now 7 enumerated, are the only ones to be found in the neck, except those which come direct from the spinal marrow, viz. the Cervical Nerves. We should now trace the Par Vagum. It will be found to be swollen into a sort of ganglion, where it emerges from the scull, and to be intimately connected with all the other * See Note upon this, in the deep dissection. 200 nerves under the angle of the jaw. The first distinct branch- es which will he found rising from it, are two small nerves, which go to the pharynx : at about an inch farther down, a large branch will be seen going off from it, obliquely down- wards, and across the neck, to pass into the larynx, between the thyroid and cricoid cartilages, this branch is called the Superior Larun^eal. The trunk of the nerve may then be traced down by the outside of the carotid, giving off no branches which have names, until it passes into the thorax. But as yet, we should not follow the nerve farther than the first rib; however, by looking 1 between the oesophagus and larynx, we shall discover the first branch which it gives oft' while in the thorax; for it is a Recurrent nerve, which comes back into the neck, to pass into the larynx, between the lower part of the thyroid and cricoid cartilages : it? branches unite with the superior laryngeal ; it is often cal- led the inferior laryngeal nerve.* The Symprtfhetie is now to be traced. We shall first ob- serve the enlargement of it under the parotid ; this is called its superior ganglion, from which it sends off branches to every one of the other nerves. As we trace it down the neck, we shall observe that it sends twigs to the cervical nerves, and nl-o some very soft delicate filaments to the arte- ry, which, from their appearance, have been called ncrm molles. About, the middle of the neck, we generally, but not always, (and oflener on the left than the right side) find another ganglion, From this, some very delicate nerves will be seen to pass, in a direction more superficial than the others; these may afterwards be traced over the aorta, to * In the distribution of the branches of the eighth nerve to the larynx and glottis, we remark that connection which so intimately unites the larynx and lungs. We observe how the slightest irritation on the former calls into activity the whole respiratory system. By its connections with phrenic and other respiratory nerves, it governs the actions of the muscles in respiration ; and being also the nerve of the stomach, by the same connections, it governs the muscles in vomiting, combining them in a different manner, to produce that action. In vomiting and in respiration, the same muscles are in action, but they are differently combined ; and muscles which in respiration are opponents, become coadjutors in vomiting. The variety of combinations of which these mus- cles are capable, explains the meaning of that intricacy and minuteness of subdivision, which characterize the nerves of the neck and chest. 261 assist in forming the mperfaml cardiac pJevus. The branch of the sympathetic continues to pass down, until it comes to opposite the first rih, and there it forms the tower cervical ganglion, from which branches go to encircle the subclavian and lower thyroid arteries. But here, we must for the present give up the pursuit of this nerve. We should now turn to the dissection of the lateral part of the neck. If we carefully dissect the anterior scalenus muscle, we shall see the Phrenic, or great internal muscular nerve of respiration, lying upon it ; upon tracing this nerve back, it will be seen to arise from several of the cervical nerves.* By then dissecting on the lower edge of the scalenns, and by throwing out the arm, we shall see a certain number of these cervical nerves, pissing to form the axillary plexus, viz. the four inferior cervical, and the first dorsal. But be- fore we trace these nerves back towards the spinal marrow, we should cut to the depth of a quarter of an inch through the fibres of the scalenus anticus; and then, about opposite to where the phrenie lies, we shall see a nerve, which rises from nearly the same roots as the phrenic, and which runs under the axillary plexus, as a distinct nerve, to the external muscles of respiration : this branch, Mr. Bell has called the External Nerve of the muscles of Respiration. As we shall now have exhibited all the principal branches of the neck, we may, after making them more distinct, pase either to the dissection of the deep nerves of the scull, or to those of the thorax and abdomen. If the body is not very fresh, we should first dissect those of the thorax. The deep nerves of the scull will be more distinctly seen, if the parts have been previously soaked in water. *This nerve is generally described as rising from the third and fourth cervical : but by dissecting it carefully, we shall find that it has origins from the portio dura, and from the ninth, and also the spinal accessory. It is a curious fact, that this is the only nerve which was. previous to the discoveries of Mr. Bell, considered as a res- piratory nerve to the muscles. He has called it the Inter- nal Respiratory Nerve,- 262 DISSECTION OF THE JVERVES IN THE THORAX AND ABDOMEN. THE viscera of the thorax and of the abdomen, should, m the first dissection of the nerves, be sacrificed to it. But after the nerves have been once fairly seen, there will he no difficulty in exposing them, in union with the arteries, in future dissections. The thorax is to be opened, by removing the sternum, with the cartilages of the ribs : but in doing this, we should cut very close upon the inside of the upper part of the ster- num, as some of the nerves lie very nea.r the inner surfa'ce of the bone. If there be no disease in the viscera of the thorax, the Phrenic Nerve of the left side will be seen passing over the pericardium, immediately opposite to the apex of the heart ; the one on the right side, id situateu rather lower down on the pericardium. There will be no difficulty in showing the distribution of these nerves upon the diaphragm. The dissection of the next set of nerves requires great care. If we look to the middle cervical ganglion, or to the point of the sympathetic, where this ganglion is generally . found, some very delicate branches will he seen going oft'; and which, if carefully traced will be found passing to form the Superficial Cardiac Plexus. The par vagum should be traced into the thorax, before the deeper branches of the SympfitheHc. On the left side, the par vagum will be seen passing over the aorta, towards the lower part of the heart and the lungs* While it lies on the aorta, it gives off that branch which has already been seen running to the lower part of the larynx, viz. the Inferior Laryn^eal, or Recurrent ; on the right side, tjje recurrent passes round the subsclavian artery. 263 The par vagum* will now be found to form intricate plexuses of branches with the sympathetic, for the supply of the back part of the heart, and of the anterior and poste- rior part of the lungs. These branches form the Deep Car- diac Plexus, and the anterior and posterior Pulnwnic 1 uses ; but to see them distinctly, we shall be obliged to cut off the ribs at the angles, on one, or both sides. If we then pull up the lung, we shall be able to see not only these plex- uses, but also those branches of the par vagum, which en- circle, or run in a net-work, on the oesophagus, and which form the (Jsoptiageal Plexus.^ After these are exposed, if * The par vagum connects the larynx, pharynx, lungs, heart, and stomach; and the sympathies it produces in health and disease, are very many. Disorder of the stomach de- ranges the secretion of the larynx: a vqinit, or nauseating medicine will loosen the viscid secretion of the larynx and pharynx ; disorders of the stomach, acting through the pul- monic plexus, will occasion cough ; ( and medicines acting on the stomach will alleviate asthma. Through the plexus of this nerve, the heart and lungs are united, ever correspond- ing in action. When life seems extinguished by suffocation, (in experiments on animals) pricking the heart will be fol- lowed by respiration ; and in the apparently drowned, the play of the lungs, in artificial breathing, brings after it the action of the heart. It is well known how disease of ihn lungs affects the heart ; but it is not so generally observed how much disease of the heart resembles pulmonary dis- ease. Looking to the distribution of the par vagum on the sto- mach, and the plexus of the nerve, in its course upon tho oesophagus, it will not appear surprising, that disorder of the uterine system, atfecting the stomach, and also primary dis- orders of the stomach itself, should produce the gtobv* hys- iericM^ or paralysis, or spasms of the pharynx and oesopha- gi**. Although the heart a ud stomach be separated by. the diaphragm, yet through this nervous cord they are united ; and this explains why disorder of the stomach should pro- duce such changes on the heart's action. The pause, or in- termission of tlie pulse, which, in many diseases, is a fatal symptom, is often produced in a manner less alarming, merely by irritation of the stomach. Seeing these many connections of the stomach with the vital parts, through this nerve, our surprise ceases at a blow. on the Stomach proving instantly fatal. fin the dissection of the camel, we discovered a very 204 we merely tear, up the pleura, we shall gee the continuation of the sympathetic upon the inside of the ribs, forming, at each intercostal space, a union with the dorsal or intercostal nerves, through the medium of a small ganglion. If we then trace the sympathetic backwards, we shall find that it encircles the subclavian artery with a plexus of branches, from the anterior part of which, those going to the viscera of the thorax pass oft', while the deeper branch forms a dis- tinct ganglion, and then passes down along the ribs, as that nerve which according to the old nomenclature, was called h e Intercostal.* By now tracing the oesophagus through the diaphragm, we shall see the united branches of the par vagum passing upon the cardiac part of the stomach, to form the plexus which has been celled the Corda Ventriculi. We should then look to the side of the chest, and we shall see three or four branches passing off from the sympathetic towards the bodies of the vertebrae: th;re they unite and form^a division, which is called the Anterior Splanchnic, which will be found to perforate the' diaphragm. By looking on the abdominal side of the diaphragm, we shall, by pulling upon the nerve within the chest, discover that a large g : anglion is formed immediately by the root of the cceliac artery : this, being of a crescentic shape, is called the Semilvnar Ganglion ; but it has more the appearance of a lymphatic gland than of any part belonging to the nervous system. From the gangloiri of each side, branches pass off, to unite together, and with those of the par vagum. so as to form a great plexus, which has been called the Cceliac Plexus, of, more commonly, the Solar Plexw ; from which, we may trace branches to each division of the viscera. If we lift up the liver, we shall see a set of nerves passing along the he- patic artery, and which form the Hepatic Plezux. If we dis- sect in the course of the splenic artery, we shall see the Splenic Plexus ; and, in the same manner, the Renal Plexu* beautiful plexus of nerves upon the oesophagus; these were in connection with a set of branches on the upper part of the pharynx. As these were also seen in the calf, and not in the asSj it is reasonable to suppose that they are peculiar to the ruminating animals, to combine the actions of the pharynx and stomach. * In dissecting the deep nerves of the thorax, we should place the body so, that the viscera of the abdcmen shall drag- down the diaphragm. It will be still better to open the ab- domen, and to remove all the small intestines, before the dis- section of the nerves of Uae thorax is completed. to the kidney ; and the Superior and Inferior Mesenteric P/tu * mes to the small intestines ; and also the Spenmtic Plexus to the testicle, and the Hypogastric Plexus to the bladder. In dissecting these plexuses, we should put probes under those which have been exposed, that they may not be lost while we are in search of the others. If, after these nerves of the viscera have been shown, the peritoneum be lifted up from the spine, the sympathetic will be seen passing from the thorax, along the lumbar vertebrae,* and forming connexions with each of the lumbar nerves, by a, series of small ganglions ; and if we follow it into the pel- vis, \ve shall find that it is connected with the nerves which pass to the leg. The sympathetic of the two sides will at last be found united on the extremity of the sacrum, forming a small ganglion, which is called the Coccygeal Ganglion , or This description is very superficial ; but I hope it will be sufficient to enable the dissector to make out what, is com- iion Sin c Pari. is description is ient to enable t] monly considered the anatomy of these nerves.f But 1 * A small division of the nerve which sometimes comes oft' from the sympathetic, about opposite to the llth or 12th rib, and passes to the ganglion, or to the renal plexus, is called the Lesser Splanchnic, or Accessory. f During the inquiries which have of late or years, been carried on in Windmill-Street, into the distinctions in the structure and uses of the several nerves, none of the experi- ments have been repeated which were instituted by several gentlemen, to discover how far the functions of the stomach are influenced by cutting the per vagum. It has not been from indolence, that they have been neg- lected, but from a conviction, that such experiments could not be attended with any satisfactory results. Perhaps it will be allowed, that the conflicting reports, which have late- ly been drawn up by the gentlemen who have been engaged in these experiments, warrant the opinion which had been previously formed by Mr. Bell, that the par vagum was a bond of connection between the several organs, and not a. source of nervous energy to the stomach. This opinion was founded on the minute examination of the anatomy of the several nerves, and particularly on the fact established by comparative anatomy, that stomachs of the most powerful digestion, in the lower animals, were independent of the par vagum : which is proved by the very conclusive evi- dence, that in many of those animals, there is no par vagum. The use of the nerve, and the phenomena which take place 266 Would advise the student who is anxious to know the subject minutely, to repeat the dissection frequently in the lower upon cutting it, may, perhaps, be understood by the investi- gation of comparative anatomy ; for by it, we shall find, that the existence of this nerve depends upon the manner in which an animal respires, and upon the connection which there is between the/ stomach and the organs of respiration. And as, in complicated animals, the par vagum passes to the throat, the larynx, the heart, the lungs, and the stomach, we may be permitted to draw the conclusion, that it is for connecting and combining, into one great system, these se* veral organs, each of which, has the power of performing. to a certain extent, its own peculiar function : but if it be cut through, then the connexion between all the organs, and also with the external muscular apparatus, upon which imperfection of the economy of each depends, must be de- stroyed. From what I have seen in experiments on the portio dura< and other nerves of the neck, I can readily believe in the ef- fects of the galvanic influence on the par vagum, when divi- ded : indeed it would be unwarrantable incredulity to doubt it, after the assertions that have been made. But still the question is open, whether the phenomena are to be explain- ed in the manner proposed by Dr. Philip. If we pinch the divided portio dura, the muscles to which it goes will be slightly convulsed, if we touch it with acid, they will be more so, but when we galvanize the nerve, the muscles will be thrown into full action : thus, it would ap- pear, that the energies of a nerve are excited in proportion to the degree of stimulus. From these experiments, it would be as just to call a pair of pincers, or an essential oil, or an acid, the nervous agent^ as the galvanic pile. Before instituting the experiments with galvanism, the fact was assumed, that by dividing the par vagum in the neck, all connexion between the brain and the stomach must be destroyed. This I cannot agree to ; for by a careful dissection of the nerves, I find that, at every point of the ab- domen and thorax, the par vagum and sympathetic have in- timate connexions with the spinal marrow, and conse- quently, through it, with the brain. I trust, that in examining a point of physiology which inust depend so much on the facts of anatomy, it will not be considered invidious in me to question how far the anatomy of the nerves has been attended to, in the experiments, and in the discussions which have taken place upon it. I think it will be admitted, that the greater number of the 267 animals * and then I hope, with the assistance of the hints which are given in the notes, that he will be able to make late experiments appear to have been founded on the views of the anatomy of the ganglionic system of nerves, which were.given by Bichat. Although I will, in common with every one, acknowledge Bichat to have been a man of the most brilliant talents, yet I will venture to assert, that his description of the anatomy of the nerves, as it now stands, is incorrect, and consequently, all his ideas on the gangli- onic system are untenable. If this be granted, it follows, as a matter of course, that all experiments which have been instituted under the idea that Bichat's anatomical observa- tions were correct, must be liable to objections. However, in justice to the memory of Bichat, I must mention the cir- cumstance told by his biographer : that he had commenced a review of the anatomy of the nerves ; and that he had been actually engaged in examining the cervical ganglions, on the very night in which he met with the accident which led to his death. It would appear from this, that he had some sus- picions of the accuracy of his former labours ; with which, 'however, those who have followed him, have been content. In proof that the anatomy has not been sufficiently attend- ed to, in conducting these experiments, I may remark, that from the intimate manner in which the sympathetic and par vagum of many animals are united, where they lie by the side of the larynx, the sympathetic must frequently be di- vided with the par vagum, when the experimenter lias sup- posed that he has cut only the latter nerve. That this has happened in the experiments on the horse, I have not the slightest doubt: for I have found it very difficult to separate these two nerves from each other, even in the dead animal. If this has taken place, (and which I have every reason to believe,) these experiments have shown, without the opera- tor's appearing to have been aware of it, the very curious fact, that whether the par vagum be cut singly, or with the sympathetic, the same consequences follow. The most extraordinary circumstance, regarding these en- quiries, remains to be noticed. The same gentlemen, after having made a great many experiments, have, during their last trials, come to a very" unexpected conclusion, and one which they did not contemplate at first, viz. that the powers of the stomach, when cut off by the division of the par va- gum, may be restored by the approximation of the divided ends, and that if a portion of the nerve be removed, the power of digestion will be renewed by forming a chain of 268 his, which has hitherto been considered a fagging* task, i* pleasing and interesting subject of inquiry. connexion between the brain and the stomach, by means of galvanism* The experiments from which these opinions are deduced: and which are, as yet, very few, are founded on the assump- tions (which has already been denied) that the power of di- gestion is conveyed from the brain to the stomach, through the par vagurn. In the next place, it is assumed, that by cutting out a portion of the par vagum, the connexion be- tween the brain and the stomach is cut off. This I must ob- ject to, when I see the intimate connection which there is, at every point of the thorax and abdomen, between the par vagum and the spinal marrow, and of course with the brain. We have in our experiments, found, when the power of a muscle depends on a certain nerve, that by simply cutting the nerve, the same effects are produced, as when a portion of it is cut out. In proof of this, I offer the experiment of dividing the portio dura, in the horse or ass. The zig-zag structure of the nerve, appears to me to render it almost im- possible, when it is cut, that its ends shall remain in contact ; at all events, the degree of retraction, that we always see in the portions of a divided nerve, entitles us to call upon the supporters of this new doctrine, to prove, that the ends of the nerves continued in contact in those rabbits in which the nerves were cut, and the digestion went on. It may also be required of the experimenters, to show, that the functions of the stomach will be restored by bring- ing the ends of a nerve again into contact, from which a por-> tlon has been removed, If the idea be correct, that there is a great and immediate difference between the consequences of simply dividing a nerve, and the removing a portion of it, will it not follow, that little or no effect would be produced by the application of a ligature on the par vagum, since by this, ther/if connexion will not be broken ? 269 DISSECTION ON THE DEEP JYERFES OF THE HEAD. BEFORE the student commences this dissection, he should furnish himself with a mallet and chissels, small saws, pin- cers, delicate hooks, and a magnifying glass. He should also have the base of a scull always lying before him. The manner in which the nerves arise from the brain, has- been pointed out at page 170. The 1st, or Olfactory, passes into the cribriform plate of the ethmoid bone, but its structure is generally so soft, that we cannot trace its filaments. The lid, or Optic, we see entering into the foramen opti- cum. We shall afterwards, in the dissection of the eye, find that it passes forward, without giving off any branches ; but to be expanded, as the Retina, in the interior of the eye.* We should now take hold of the dura mater which lies upon the frontal bone, with the pincers, or strong hook, and pull it off, towards the temporal and sphenoid bones. This requires some force, but it must, at the same time, be carefully done, particularly near the edges of the foramen lacerum, or we shall tear off some of the small nerves which pass into the orbit. Indeed, the third, and the fourth (which lies in the sphenoidal fold) should be partly exposed before the dura mater is torn down. When the membrane is torn from the sphenoid and tempo- ral bones, the Ga-sserian Ganglion of the Vth will be seen, from which there pass off the three grand divisions, viz. the Ophthalmic, passing through the foramen lacerum, into the orbit, iheJSuperior Maxillary, through the foramen rotun- dum, to the upper part of the face, and the Inferior J\laxilla~ ry, (which is divided into the dental and gustatory,) through the foramen ovale. The first nerves to be followed, are those which pass through the foramen lacerum into the orbit, viz. the third* the fourth, thejirst division ofthejifth, and the sixth. * Before exposing the course of the nerves which pass through the several foramina, we should attach coloured threads to them, by which we shall easily find them > during the course of the dissection. 270 Before we can trace these nerves, the orbit must be open- ed, by carrying the saw through the orbitary plate, in a line drawn from the middle of the foramen opticum, to the inner angle of the superciliary ridge, keeping about half an inch t6 the temporal side of the crista galli.* The os mala? is then to be cut to the depth of three-quarters of an inch, on a lev- el with the zygomatic process. The saw is then to be car- ried through the temporal process of the sphenoid bone, and the squamous part of the temporal, nearly to a level with the sella turcica. By a smart blow with the mallet, the roof of the orbit will now be so loosened, that by cutting close upon the bone, it may be entirely detached from the soft parts. We shall now have so exposed the orbit, that we may make the dissection of the nerves in it. The first nerve which will be seen, is a branch of the ophthalmic division of the Vth. It is the same which, in the dissection of the face, was found coming through the su* perciliary hole, to be distributed on the forehead. A black hair pin should be put under it to mark its situation. In tracing it, we shall find that it gives off two principal branch- es?, one to the lachrymal gland, and the other to the nose. This last one should be marked by a bristle or pin, as it must afterwards be minutely traced. As the IVth is very small, we should first look for the trochlearis muscle, upon which it is distributed, and then we shall see some of its fibres. By tracing them back, we shall discover the trunk of the nerve, which is not larger than a thread. The third will be found at its entry into the orbit, lying very close on the optic nerve. It almost imme- diately divides into several branches, one of which, in its course towards the obliquus, and at about three quarters of an inch from the foramen opticum, and on the temporal side of the optic nerve, will be found to form a union with the nasal branch of the Vth, (already described,) through the medium of a small ganglion whch is called the Lenticular. Prom this ganglion, a number of small nerves pass into the coats of the eye : these are called the ciliary nerves. The sixthis the last nerve of the orbit, to be dissected. It enters upon a lower level than any of the others ; and it passes through that spongy structure of the dura mater, which is railed the cavernous sinus, there is an intimate connexion be- 4 tween it and the sympathetic, but this union will be more * It is presumed, that the dissection of all the superficial nerves has already been made ; and that, therefore, there can be no hesitation in cutting through some of the superficial branches of the Vth, and of the Vllth. 271 particularly described presently* The trunk of the nerve will be found to be almost entirely distributed upon the rec- tus externus muscle.* We must now follow the other branches of the Vth pair. This we shall find to be a most difficult dissection, and one* in which we are often, after much labor, foiled, by an un- lucky blow of the mallet and chisel, f * In dissecting the nerves of the orbit, we should disturb the natural situation of the parts as little as possible ; and af- ter the dissection of each twig, we should mark it, by putting a black pin or bristle under it. f Mr. Bell has, in his late lectures on the nervous system, shown that all the spinal nerves, the suboccipital and the Vth, have several essential circumstances, in common : that they have each two distinct roots, that they have each a ganglion on one of their roots, that they are all exquisitely sensi- ble, that they are all distributed to the muscular frame, for locomotion and action, that each nerve is distributed to its corresponding division of the bodily frame, without ever taking a longitudinal course on the body, and finally, that these nerves are common to all animals which have a symme- trical body and a regular nervous system. This view will more easily be understood, by referring to the plan in plate I. When we examine the origin of the nerves minutely, we shall fmd that the Vth is the only nerve of the scull which comes oiFin such critical circumstances, as to have a root from the crus cerebri, and another from the crus cerebelli, which parts may, by comparative anatomy, be proved to be the continuations of the anterior and posterior divisions of the spinal marrow. The Vth will also be found to be the only nerve within the scull, which has a ganglion at its roots. Those who have dissected the deep nerves of the head, or who have attempted to demonstrate the branches of the Vth pair to students, will be able to estimate the value of thin view. I have examined the nerve repeatedly, in its whole course, in man, in the horse, the ass, the calf, and the dog. By these dissections, I have been convinced, that in every re- spect, the Vth pair resembles the spinal nerves, even in thr peculiar form of its ganglion and plexus. In the horse, therp is as distinct a plexus formed by the branches of this nerve which go to the different parts of the head, as there is form- ed by those which go from the axilla or loins to supply the limbs. I conceive, also, that the form of the part from which this nerve arises, is analogous to that of the spinal marrow where t}ie axillary nerves take their origin. If this 272 The eye, with its muscles, nerves, &c. may be remove *ir drawn aside. The zygomatic process of the temporal bo#e is to be cut through at its roots, so is the malar process of the superior maxillary. When the intermediate portion of bone is re- moved, we may easily trace the superior maxillary of the Vth, across the spheno palatine fissure, to the orbital canal of the superior maxillary bone, from which it emerges, at the infra orbital foramen, upon the face. In its passage across the spheno palatine fissure, it gives off some important twigs ; but before we can show these, we must remove a great deal of the pterygoid muscles. By then looking close upon the bone, we shall see a confused plexus ; which, however, will be found to be principally made by the branches of the internal maxillary artery ; therefore, as many as possible of these vessels are to be re- moved : we shall then discover two twigs, passing down to the narrowest part of the fissure, to be united with a small ganglion, which, from the name of the German professor who first described it, is called the ganglion of Meckel ; or, from its situation, the spheno palatine ganglion. When this ganglion is carefully examined, some branches will be seen passing off from it towards the palate and nose; and, from its back part, a nerve may, but with some trouble, be seen passing into the pterygoid, or Vidian hole of the sphenoid bone. This nerve (the Vidian] passes to unite with branches of the sympathetic, and with theportio dura ;* but it cannot be traced, until those of the other division of the fifth are examined. be correct, it will be another proof of the similarity of the Vth nerve to the spinal nerves. In this investigation, I have been able to correct the very Common mistake, that the sympathetic nerve has its prinei- tjonnexion with the nerves of the head, through the Vltli nerve. .The branches of the sympathetic, which appear to go to the VIth,go to the ganglionic portion of the Vth. By the establishment of this fact, it is proved, that even the connection between the sympathetic and the Vth, is sim- ilar to the union of the sympathetic with the ganglionic roots of the spinal nerves. For an account of the experiments by which the similarity of the Vth and spinal nerves is further proved, I must refer to a paper in the Philosophical transactions of the present year. * See what is said on the portio dura ? p. 256. 273 The third division of the Vth is BO large, that we shall at once see it by looking to the foramen ovale. To make if distinct, after it has passed through the hole, it is only ne- cessary to dissect carefully in the remaining part of thf pterygoid muscles. The branches which pass to the supply of these muscles, and to the temporal muscles, will then bo seen. It is presumed that the jaw bone has been removed in the first dissection, and that the dental branch is marked by a thread being attached to it. The only particular branch of this nerve that remains to be shown, is that which passe? back from the gustatory towards the glenoid fissure, (the corda tympani*). This nerve may, with some care, be traced through a small hole into the cavity of the tympanum; but in breaking up the bone, which it is necessary to do to ex- pose its course, it is generally torn. Its track across thf membrane of the tympanum, may be easily shown, by break- ing up the cavity, in the manner recommended in the dissec- tion of the ear. The foregoing is but a very slight sketch of the manner of dissecting the branches of the Vth pair ; but I hope the hints will be sufficient to enable an ingenious dissector to follow the branches to their termination. The Vllth pair will be seen passing into the foramen au- ditorium internum, where it almost immediately divides in- to the two divisions, Portio Moll-is and Portio Dura. The portio mollis is distributed entirely upon the organ of the ear. As the portio dura passes through the very dense part of the petrous portion of the temporal bone, it "is exceedingly difficult to follow ; but, with some care, it may be done, and then we shall find the union between it and the Vidian, and also with that which is called the corda tympani.f The * See the note upon the portio dura. f In the investigation of the minute anatomy of the portia dura, or, as it is called by Mr. Bell, the respiratory nerve of the face, we have been induced to consider the Vidian as that branch of the portio dura which passes to the respiratory muscles in the back part of the palate, and to the membrane of the nose ; and the corda tympani, as the twig which sup- plies the levator and tensor palati muscles : I think we may now be permitted to say, that these two nerves have hither- to been traced back from the Vth, only in consequence of their forming a union with the deep branches of the Vllth, similar to that which is formed by the superficial branches of the same nerves on the face. The dissection of the nerves in the horse would lead us to 1171 . e will bo found to emeruli i havo ronstitntod t'c mce \vhioh phy,- inad( x in tho proson.t day. Tho vory ourio'i Mits which \voiv in: t itn'od h\ him to investigate fho use f 'his IKTVO, \vill ho foinul in tlit 1 rhilos(>phic;il Transactions. Tho compriiv.tive anatomy of f!;oporlia wo\rr, 1 shall i. diico tho following observations on its distribution in tho olc- pbant : 'During tho last winter, when engaged in as.visfmcr !\| .-. Hell in the investigation oft! .-\s{im, ! HM! tho me- nge, to study t!' and use of the prohosri> of th il : and' tins I i H'ood oj>portunity of utlo, that he permitted metO l;::.n 'Io his trunk tree' Prom the o-rea! power which the elephant has over his triuik, 'Machine, I '.-d that there must be lan'.'e nerves running to it, similar to thoso which supply the , ?uan : hut as the n an i:up<-rhint part in tho respiratory system oi ,-i:il, I thought tluif in tin 1 re would be t!io mpsl curacy or faHnev of opinir-n on tho |>orlio dura. Tho animal died in Hie month of May : and, through the kindnt^s of my fn Mid, Mr. IVinvo, WMO pnrohasod if dy forthopurp lection, I was enabled t.o m.iK examination of thononvx /ir// the broken processes are to be torn off with a strong pa nippers. heath of the spinal marrow v; ill then be expo When it i~ opened, we -hall see the origins of arid the trunk, passing up to unite with the fib.-- the par van-urn and glosso pharyngeal, which have - be traced through the foramen lacenim, with th- jugular vein. As soon ^ they emerge from the scull. rate. The par :] be found to form ganglion, just at its exit from the scull. it passed from behind the jaw to th ' as an entire nerve, and of the size of the sciatic nerve in man in its .:ail branches to th' muscles of the- the ear. and to a .- muscle which corresponds with the platysma. Before it passed into thesul;.- *.iie proboscis, it . ted with the second division of the Vth paii. which c out from the infra orbital hole, in two large branc two nerves being then closely u; ; layers of aich form the greater part of the tr The portio dura became quickly diminished in size. : gave off its branches in great to the muscles : the Vth was contin- .-ery large nerve, to nearly the extremity nerv :gers in rnan. Onmaki::;. boscis, near its extremity, a great number of these n were seen in if .ce. A few branches of the portio dura ran to the valvular ap- paratus in the upper part of the trunk : but this peculiar pair, which was about the size of the radial nerve, and v. jit from the nriin br The exam, me animal who- bosci r. and n< ' ane time a resr-i: gan, would rr ; y at pro- sent be taken cs a proof, that wh^re the par' an or^ no portio dura. i very T remarkable nerve. In all animals in 276 The IXth pair will be found to come, by a single set of fil- aments, from the corpus pyramidale, and to pass through which it is found, it is intimately connected with the respira- tory nerves. If an animal does not perform part of the act of respira- tion by muscles which run from the scull to the chest, no spinal accessory, or superior external respiratory, as it is called by Mr. Bell, will be found. A common example of this may be seen, in any of the larger birds, as the swan, &c By experiments on the ass, we have proved, that, by cut- ring this nerve, we can paralyze the muscles to which it goes, AS muscles of respiration,- though the same muscles, being still supplied by other nerves, will retain their powers of raising the head, &c. During the month of April last, there was an excellent opportunity aiforded of corroborating the opinions which JVIr. Bell has formed on the use of this nerve, by the dissec j lion of the Courier Camel, or Maherry, which was brought from the interior of Africa by Captain Lyon, as a present to his Majesty. In the dissection of this animal, \Ve noticed many interesting facts, which have been overlooket! by com- parative anatomists, and particularly the distribution of the nerves of the neck and stomach. The arrangement of the nerves which combine the muscles of the throat and stom- ach, in the act of rumination, is very beautiful. But at pre- sent I shall confine my remarks to the spinal accessory, or superior respiratory nerve. The structure of the neck of the camel is very different from that of the horse or bullock. It more nearly resembles that of a large bird, such as the swan, to which, in the slow and successive motions of the head, it has a great resem- blance. Although we discovered, by dissection, that there was a great similarity in the muscular apparatus of the neck, to that of birds, we did not expect to find, that the arrange- ment of certain nerves would also correspond; and, at first, we were rather suprised that we could not find a spinal ac- cessory nerve in union with the VIHth, under the jaw, as we had found in all the other quadrupeds which we had ex- amined. However, on comparing the muscles of the neck, with those of the horse, a great difference was found; for. although there was the sterno maxillaris, which, in the horse, receives the greater part of the spinal accessory, yet it was so small, that it could have no power over the motions of the chest, as it has in the horse, ass, &c. In the lower part of the neck, there are several muscles corresponding to the scaleiu, which, besides the common cervical nerves 277 the foramen condyloicteum, direct to the inuscles of the tongue. We may now examine the manner in which each cervical nerve .arises from the spinal marrow. We shall find that each nerve has a double root, i. e. one from the anterior, and the other from the posterior column of the spinal marrow ; that the one from the posterior has, immediately before it joins with the anterior, a ganglion formed upon it ;* and if rve. carefully examine this, we. shall find, that from each ganglion a small nerve is sent off to unite with the sympa- thetic, f To trace the sympathetic through the foramen caroticum, and to show its connexions with the nerves within the scull, it will be necessary to sacrifice the greater number of thu other branches. When the foramen caroticum is opened, u, plexus of nerves will be found surrounding the carotid arte receive a blanch which arises in common with the phrenic. By this nerve, these inuscles are probably combined in ac- tion with the other muscles of respiration ; while the mus- cles on the upper part of the neck, from their comparative size, appear to be of as little use in producing respiratory motions of the chest, as those of a bird ; and this, we may be allowed to presume, is the reason, why there is no spinal accessory, or superior respiratory nerve, but only a branch, rising in union with the phrenic, to supply the respiratory muscles on the lower part of the neck. * Some curious experiments have been made in Windmill- street, on the comparative degree of sensibility of the two origins of these nerves. . Though in these experiments there was sufficient observed to induce us to believe that there is much difference between the two sets of fibrils,- yet, from the difficulty of making them, the facts are not yet so distinct as to permit us to mention them. f This union or origin of the sympathetic, appears to have been entirely overlooked by Bichat. He has described tho ganglion, but not the nerve of communication. Had he lived, ui all probability he would have investigated the anatomy farther , and then he might, perhaps, have given up the idea of considering the sympathetic as a part entirely distinct from the system of the spinal nerves. It is a striking and curious fact, that in the edition of his Anatomic Descriptife, publish ed in 1802, the editor says : " Nous reprenions ensemble J systemenerveux des ganglions et c'etoit le soir meme ou nous avions commence le ganglion cervical superieur, que Bichat tit cette funeste chute qui determina sa derniere maladie." Z 278 ry, which appear to be united witlr the Vlth, but when carefully traced, will be found to pass over the Vlth to the Casserian ganglion of the Vth.* There will also be branches seen passing along the Vidian nerve towards the ganglion of Meckel. DISSECTION OF THE PARTS OF THE JfOSE-dJVD OF THE EAR. AFTER having finished the dissection of the nerves, Hi' scull should be divided, so that we may have an opportunity of examining the nose, and some parts of the ear. The section of the scull may be made by carrying the saw through the remaining part of the bones of the head and face, in a perpendicular line, but a little to one side of the septum narium. The soft palate, &c. is to be cut in the same direction. Each of the sections will afford us some ve- ry useful views, particularly if the pharynx and larynx be left attached to one of them. Indeed the anatomy of the posterior nares, &c. is so important, that the student should always examine it, even though he should destroy many of the small muscles. The eavities of the nose will be made more' distinct, by cutting (in one of the sections) through the superior maxilla- ry bone, immediately below the orbital plate, and by contin- uing the cut in the same line, through the ethmoid and sphe- noid bones. * Professor Boch, of Leipsic, and M. Cloquet, of Paris have, in prosecuting the minute anatomy of the sympathetic nerves, discovered a small ganglion in the cavernous sinus. This I have often seen : but I think I have also shown, by the dissection of these nerves in the larger animals, that it is quite an error to suppose that the principal connection be- tween the sympathetic and the nerves of the head, is through the Vlth pair. By an attentive examination, it will be found that the branches of the sympathetic, which appear to unite with the Vlth, pass along it, and unite with the ganglionic portion of the Vth. The branches of the sympathetic which actually unite with the Vlth. are very small. 279 We may then see the mucous membrane which lines all the interior parts of the nose, viz. the Schneuhrian membrane; the inferior Spongy bone ; the labyrinth formed by the eth- moid bone ; the communication between the cells of the frontal, ethmoid, and sphenoid bones: immediately above the inferior spongy bone, we shall see the opening- into the antrum of Highmore L and below the bone, the passage to the lachrymal sac. On the other section, the septum narium will be seen to be formed by the union of the perpendicular plate of the ethmoid with the vomer, through the medium of a cartilage. Bylookingto the posterior part, we can under- stand the relation o <" the passage between the back part of the nostrils and the throat the posterior nares ; and, with a little care, we may discover the Ei-stachian tube, which leads into the cavity of the Tympanum. We may now take an opportunity of examining the gene- ral anatomy of the ear. The following description of the manner of dissecting the ear, will perhaps enable a young student to acquire a gene- ral idea of the relative position of the parts composing the organ. To comprehend the minute anatomy, requires more opportunities than a dissecting-room generally affords. The muscles of the cartilag-es of tiie external ear, are ge- nerally so small, that unless the dissection be made in a very ileshy ear, as in that of a negro, it will be impossible to find them ; but those running from the head to the ear, may al- ways be easily found.* * The following table of these muscles is added : MUSCLES LYJNG ON THE CARTILAGES OF THE EXTERNAL EAR. HELICIS MAJOR. OR. The upper and acute part of the helix, anteriorly. IN. Into its cartilage, a little above the tragus. HELTCIS MINOR. OR. The inferior and anterior part of the helix. IN. The crus of the helix, near the fissure in the cartilage, opposite to the concha. TRAGICUS. OR. The middle and outer parts of the con- cha, at the root of the tragus. IN. The point of the tragus. ANTITRAGICUS. OR. The internal part of the cartilage t;hat supports the antitragus. IN. The tip of the antitragus, as far as the inferior part of the antihelix, where there is a fissure in the cartilage. The several cartilages may be exposed by merely rendering the skin, &c. which covers them. The cartilaginous tul* should be followed down to the bone. The squamous pail of the temporal bane should then be cut, down to the level of the pars petrosa; and we should proceed to lay open the different cavities of the internal ear. The bone immmediatcly behind the squamons portion, and in. a line with the posterior part of tfie tube, is so very thin, that the slightest blow .with a small chisel will break it : if the fracture be made posterior to the line of the meatus ex- , ternus, the mastoid cells will be opened. After having done this, it is very easy to expose the whole cavity of the tympa- num, by breaking up the thin bone, in the direction towards the foramen spinale of the sphenoid bone. The membrane of the tympanum, with the chain, of bones, vvill now be seen, and also the communication of the tympa- mm with the mastoid cells ; and if a fine probe- be pushed ta- wards the fere part of the cavity, it will pass into the Eu- stachian tube ; but it will not be possible to push the probe in- TRANSVERSUS AURIS. OR. The prominent part of the concha on thedorsum of the ear. IN. Opposite to the outer side of the antihelix. These muscles are for the most part scarcely discernible : they are, no doubt, for giving- rigidity to the ear, the bettr to enable it to collect the sound. MUSCLES OF THE EXTERNAL EAR. ATTOLENS AURIS. A thin and almost tendinous sheet. OR.- The tendon of the occipito-frontalis, where it cove** the ape-neurosis of the temporal muscle. IN. The upper part of the ear, opposite to the antihelix. ANTERIOR AURIS. A membranous muscle also. On- Back part of the zygomatic process of the temporal bone. IN. The back of the helix, near the concha. RETRAIIENTES AURIS. Two delicate membranous mus- . rles. OR. The mastoid process, above the insertion of the v^terno cleido mastoideus. IN. That part of the back of the ear which is opposite to he septum that divides the scapha and concha. These muscles, in a state of nature, are designed to give /tension to the ear; to make it more capable of receiving sounds, and especially tobring us acquainted with the di- rection of sounds ; but their use is, in general, almost civ tirelv lost. 281 be throat, without injuring the little bones in' the tympa num, the tube, therefore, should be examined in the throat. * As we have determined to sacrifice the bones, for the purpose of examining the eye, nose and ear, the following cuts should be made: t the lower jaw having- been removed, the saw should be carried in a line parallel with the cavity ot the tympanum, cutting through the glenoid cavity, and ter- minating in the foramen ovale of the sphenoid bone ; another cut (if the orbit has not yet been opened) should pass through the os malae, at its union with the superior maxillary bone, and be carried in a 'line through the frontal and sphenoid bones, so as to meet the first cut into the foramen ovale ^ when the triangular piece of bone which is included between these cuts, is removed, it will be easy to show the whole ex- tent of the Eustachian tube ; and if one half of the soft pal- ate be cut away, the trumpet mouth of the tube will be ex- posed ; and now a small probe (for, at one point, the tubo is very narrow) may be passed into the tympanum ; the tube may be laid open, "thro ugh its whole length, with a pair of strong scissars. We shall now be convinced of the imprac- ticability of passing a probe into the ear from the mouth. The mere possibility of doing it from the nostril, will be- seen. It is now easy to understand, that if the Eustachian tubf* be closed, after an ulcerated sore throat, deafness may be the consequence ; or how temporary deafness is frequently oc- casioned by catarrh. In proof of the cause of this, we shall iind, that in children who die of cynanche, the tube is generally ftill of purulent matter. It must also be evident, that, in those people who can throw smoke from the mouth, out by the ear, tj|e membrana tympani must be in part des- *royed. Besides the bones, (the Jifaleus, Incus, Orbiculare, and Stapes,) there are certain small muscles within the cavity of tlte tympanum ; but these are very difficult to show. On the upper part of the Eustachian tube, a muscle lies, partly ui a cavity, which, in the dry bone, being something like a marrow-spoon, has been called the Spoon-like Cavity ; upon the extremity of which, the tendon of the muscle is reflected, and then runs to the long process of the malleus. This mus- cle is called the Tensor Tympani. From the opposite sid( of the Eustachian tube and glenoid fissure, another muscle * The following directions for cutting the bone, were writ- ten under the ida, that the dissection of the ear was to bt the principal object : it will be easy to vary the cuts a lit it" the posterior flares, &c. have already been examined, 232 passes, to be inserted into the malleus ; it is the Laxaiur Tympani. From the upper part of the tympanum, there is & thira muscle, which runs to the short process, and is called the Superior or External muscle ; but this last,, is denied by many to be of the nature of muscle. There is- still a very small muscle attached to the stapes, it is called Stapedius, and takes an origin from the interior of a little eminence, ab- surdly called pyramid. The corda tympani nerve, which has already been described at page 273, will be seen running across the membrane of the tympanum, and over the long process of the malleus. Although these muscles are now mentioned, it is not pos- sible to see them, all in this stage of the dissection, as the tympanum has not yet been sufficiently opened ; but to ex- pose it more at present, for the purpose of exhibiting these muscles, would endanger the parts composing the labyrinth* It is almost imposible for any one but an experienced dis- sector ,. to exhibit all the parts of the labyrinth, in one view. To do this, he must have a knowledge of each part ; and to expose them, he requires a variety of little instruments, as small chisels, files, and saws ; but it is possible for any one to make such a dissection, as will give a general idea of the relative situation of the parts. About a quarter of an inch posterior to the meatus internus, a ridge will be seen cross- ing the petrous portion ; if this surface be fried down, a ca- vity will be opened, viz. the Superior Semicircular Canal. This canal may be easily followed, by putting an awl into its cavity, and then, as with a lever, breaking up the bone : bv tracing it towards the cavity of the tympanum, we shaft show its communication with the Horizontal Canal ; by tra* cing its oth^r end, we shall open the Internal Canal; but it is very difficult to follow these two last carlals through their whole extent. The Vestibule may be opened by breaking the bone with a small chisel, immediately anterior to the union of the superior and external semicircular canals,- or a. better mark, is the base of the Stapes ; but in making the cut, we are very apt to break up the foramen ovale; To show the Cochlea, a slanting cut should be made across the meatus internus, towards the Eustachian tube. If this be done with a very fine saw, it will probably pass through the Modiolus, so as to give a view of all the parts of the cochlea; but in making the cut, the ssrw-dust will so fill the Scales Cochiece,thai it will be impossible to see them until they are cleaned ; but we must not put any instrument into the coch- lea to clean it ; it should be done by dipping the preparation into water, and blowing forcibly into the scalae with a bl We may then, perhaps, make the Modiolw and 283 miua Spiral, with the bifundibulum, distinct. I shall noi imter into a more minute description of the parts, but shall refer the student to go'od books of anatomy ; he will find threat assistance in the Plan of the Ear, published by Bur- gess and Hill, and which is copied from the drawing used in Windmill-street, for the demonstration of the internal struc- ture of the ear. DISSECTION OF THE E YE, As the parts of the human eye are not only on a small scale, but as we can seldom procure them sufficiently fresh for the dissection of the minute parts, we should have much difficulty in acquiring a knowledge of the structure of the eye, as an organ of vision, were it not that we have it always in our power to get the eyes of sheep, pigs, or oxen, in t>. perfectly fresh state. Indeed, we shall find it advantageous to dissect the eyes of some of those animals, before we exam- ine the human eye ; because, in them the important parts oi the organ are not only the same, but they have this great su- periority over human eyes for dissection, the being much larger. But to understand the eye, as a part upon which surgical operations are to be performed, we must carefully examine the human eye, and accurately mark the proportion- ate size and relative position of each part. It need hardly be said, that the eye-lids, and the lachry- mal apparatus, muscles, &c. must all be studied on tin* human body. The eye of a sheep is a very good subject for dissection ; but the eye of a pig, in some respects, more nearly resembles the human eye. The dissection- of the eye of the horse or ox will be found very useful when we wish to examine some- of the minute parts. Before endeavoring to discover the minute structure of the eye, we should make several sections, to acquire a general knowledge of its parts. We may commence by dissecting away the muscles, &c. which are attached to the ball of the eye. When this is done, the Sclerotic will be seen, with th# 284 transparent Cornea attached to its anterior, and the JV m r < perforating its posterior part. If we puncture the cornea, the Aqueous Humour will es- cape : if we cut out a portion of the cornea, we shall see the /m, with its central hole, called the Pupil. By now pres- sing on the ball of the eye, the Lens will be pushed forward into the pupil : by scratching with the point of the knife, we' shall open the capsule of the lens ; by increasing the pressure on the ball, the lens will start through the pupil, and then the Vitreous Humour will appear pushed forward into the pupil. But as the capsule of the vitreous humour (tunica hyaloidea) is very different from that of the lens, the mere scratching of its anterior part will not be sufficient to evacu- ate the humour ; but to do this, the instrument must be plunged deep into it, and be moved in several directions : by then squeezing the ball, an aqueous humour will exude. Another eye may now be cut through, at half an inch posterior to the edge of the cornea. On the ante* rior section, we shall see the back part of the iris, of a deep black colour : the transparent lens will be seen lying upon it. On the posterior half, we shall see the transparent vitre- ous humour ; and looking through it, we shall probably see the inner surface of the Choroid, because, in a very fresh eye, : the Retina^ which is interposed between the vitreous humour and the choroid, is generally transparent ; but perhaps some of the vessels of the tunica vasculosa retina may be seen, ap- parently on the back part of the vitreous humour. When we hold up this portion of the globe, and invert it, the vitre- ous humour will fall out ; and then the nervous matter ot* the retina, being exposed to the air, will become opaque, and consequently visible : but it will not keep its proper posi- tion ; it will fall back towards the bottom of the eye, so ?>' to expose the whole of the inner part of the choroid, which, in the sheep, is black and green. The choroid may now bt easily separated, with the handle of the knife, from the scle- rotic. Before we commence the examination of the minuf '< structure, we ought to fix the eye ; and this should be done in such a manner, that we may, in the course of the dissec- tion, be enabled to put the eye into water, for there are some parts too delicate to be dissected, unless they are, at the same time, supported in a fluid. Anything in the form of a small egg-cup, or pill-box, will hold the eye sufficiently steady to enable us to examine the principal parts ; but we should at once so fix it, that we may continue the dissection through the whole organ. The most convenient mode of fioing this, is to attach the ball of the eye, with a few pins., tc 285 a piece of cor-':, about an inch in diameter, and half an iiicL in depth, which has been previously hollowed out, and fixed to a saucer with sealing-wax. The pins may be pushed through the coats ; or it will be better to put the pins into the cork, and then to pass three or four threads, at different- points through the sclerotic, about half an inch from the , nerve ; the threads are then to be fixed to the pins. If it be too much trouble to make this apparatus, two small nails, slightly bent, maybe laid across each other", and fixed to v. saucer with sealing-wax ; the eye may then be easily at- tached to them. Li addition to the saucer, we should have a glass globe, one third of which has been cut off; for after the parts have been dissected, they will be seen to great ad vantage by filling this globe with water, and then inverting it over the saucer: the manner of doing this, does not re- quire much ingenuity to discover. We may now proceed to make a very minute examination of all the parts already mentioned. The transparent cornea, and the sclerotic, are so inti- mately connected, that, on the first examination, they will appear to be parts of the same coat ; indeed," we cannot sep- arate them ; yet by maceration, the connexion between them, will become so completely loosened, that the cornea will fall from the sclerotic, like a glass from its frame.- Even in the fresh state, we can show that they are of dif- ferent textures. To do this, the cornea must be cut from the sclerotic by a pair of sharp scissars(in doing which, the aqueous humour will escape), and then, by taking the cornea betwixt the finger and thumb, we shall feel that it is com- posed of several lamime, between which, there is a cellular structure, filled with a pellucid fluid. If we squeeze the ball of the eye, before the cornea is cut off, it will appear opaque, probably in consequence of the relative position of the cells being changed. When the pressure is taken off, the eye will again appear clear ; this explains the immediate good effect of puncturing the cornea, when there is effuson into the anterior chamber. This operation is frequently perfomed on horses. The cor- nea may be separated into distinct lamina?; but this will be more easily done after it has been macerated sometime; we shall then be able to discover, besides the proper laminae, a coat, upon the external surface of the cornea, which appear* to be the continuation of the tunica conjunctiva,- -and anoth- er, on the inner surface, which has sometimes been describ- ed as a capsule of the aqueous humour. This last is some- times called, from its discoverer, Tunica Wrisbcrgii. It would be inconvenient to examine the structure of tho 286 H'lerotic, at present : we may defer it until we finish other parts, or examine it, in another eye. We shall find that it is not lamsllated, but fibrous. The cornea being removed, the iris will be seen. It is almost needless to remark, that the shape of the iris in the sheep, is very different from that of man. The cut edge of the sclerotic should now be seized with , the forceps. Tlje point of the scissars is then to be gently insinuated under it, or will be better to pass an ivory or silver probe under the edge of the sclerotic, to the extent of a quarter of an inch, and then to gently move it round the circle ; this will separate the connections between the sclerotic and Lignmentum Ciliare, which is the name given to the part which connects the choroid and iris. The sclerotic may then be cut, so as to expose the outer part of the choroid: this is to be done, by first passing one blade of the scissars cautiously between the two coats, and then inclining the eye to one side, that the weight of the humours may so drag on the choroid, as to facilitate the sep- aration. After having removed a small portion of the scle- rotic, it will be well to put the saucer into a flat basin, or dish, with as much water in it, as will cover the eye. The whole of the sclerotic need not be removed, but only as much as will exhibit the external appearance of the choroid. A number of small nerves and vessels will be found running between the sclerotic and choroid, which ought to be cut, not torn. The choroid will now appear to be of a jet black colour, which is owing to a black secretion ; yet if we scrape Hie membrane with the finger, very little colouring matter will come off. But although this secretion is on its inner surface, still a little exudes through the coat ; for even in a very fresh eye, the surface of the sclerotic, in contact with the choroid, will be slightly discoloured. The iris will now be more distinctly seen, and, between it and the choroid, the white ring, which has received many names, viz. ligctmentum cilictre ; corpus ci/iare ; annulus lig-ci- mentosus ; annulus gangliformis tunicce choroidece : but the name most commonly given to. it, is Ligamentum Ciliare. The chorid consists of two lamuitB : by cutting* very carefully, with a small scalpel, through one half of the mem- brane about the middle of the eye, and by pulling upon the divided portion with the forceps, we may show both of the laminae; but it is difficult to do this nicely: how r ever, we shall at once be able to understand the difference between the two lamina?, when the choroid is separated from the re- tina ; for then, the- internal surface will appear of a bright 287 colour, and mllous^ while the external, will be dull, and cellular. The external part is called the true choroid, from its re- semblance to the chorion of the fetus, the inner part has, in honour of the discoverer, been called Tunica Ruy&ckiana: The variegated colour of the internal surface, in some ani- mals, having some resemblance to the colour of fine tapestry, has induced the Parisian dissectors to give it the name of Though we cannot make the following dissection on fhr same eye on which the internal part of the choroid has beer? examined, yet the description may now be given., The cor- nea, and half an inch of the anterior part of the sclerotic, IP to be carefully removed from the choroid : this will show the iris in union with the choroid, through the medium oi 1 the white body called ligamentum ciliare. It must be evident, at first view, that the iris is of a verx different structure from the choroid. On the latter, we sec a number of small veins, disposed in whirls or vortices, whence the name vasa vorticosa ; while on the. iris, we can not see any thing resembling them. There is not any ap- pearance in the choroid, of fibres ; but in the iris, we sec both radiated and circular,* which have been, by the besl authorities, supposed to be muscular. The colour of the two parts, anteriorly, is also very differ- ent ; for the name of iris has been given, from the variety of Colours seen upon it. When the anterior .surface is exam- ined with the microscope, a number of tilli will be seen. which are said to secrete the different coloured matters ; but when the back of the iris is examined, it will be found to In- covered with the pigmentum r.igrum, whence, from its black appearance, it has sometimes been called uvca. So far, it is sufficiently clear, that the choroid and iris arr very different from each other ; but many authors havf said, that the anterior part of the choroid is divided into two portions, viz. into the Iris and Ciliary Processes. But J think those authors must have come to this conclusion, in con- sequence of having made the dissection in rather a superfi- cial manner. To understand the true anatomy of the part. * The pigment, upon the surface of the tapetum, is g<^ ally black in men, but the secretion is of various cojours, in different animals ; sometimes it is deficient, and this i> i he appearance of the red eye, as in the white rabit, cream Coloured horse, or albino; for in them, the blood Circulating in the choroid, is seen through the pupil, while in the com- mon eye, the vessel j? are obscured by the pigmentv; 288 xvc must first examine the ligament by which the iris is con- nected to the choroid. In the fresh eye, it is so firm, that it is difficult to detach the iris; but after the eye has been macerated for some time, the iris may easily be separated from the choroid, and then the ciliary processes will be seen. This dissection may be made in two ways ; the first may be* done in an eye nearly quite fresh After the iris and part of the choroid have been exposed, we should introduce one blade of the scissars into the pupil, and cut across the iris, (but not quite to its root,) at two sides of the circle. If we then tear one half of the iris back towards the choroid, we ^hall expose the black circle of ciliary processes, lying loose on the margin of the capsule of the lens : by tearing away this portion of the iris, altogether from the ligament, we shall see that these processes are the termination of the choroid. To expose them in another manner, the eye should fee two days old. We should not now cut the cornea, but through the circle of the sclerotic, about a quarter of an inch from the margin of the cornea. We must not injure the choroid, but separate the sclerotic from it. In separa- ting these two coats, the iris will probably adhere to th sclerotic and cornea, so that when it is torn up, the ciliary jigament will be divided into two portions: the ciliary pro- cesses will be seen projecting from that part of the ligament which remains attached to the choroid. At the first view, the apices of the processes will appear to adhere to the capsxile of the lens, and so they have been described by many; but that they do not, may be proved, by blowing a little air between them and the lens: this will also show, that, at their bases, they appear to adhere to the capsule.; but they do riot actually touch it, for there is interposed be- tween them and the capsule, a membrane., presently to be described (Tunica Vasculosa Retinae). This part of thedis~ section is very difficult, and ought to be done while the parts are under water. There is still another method of giving a, view of the ciliary processes. This is, to make a section of the anterior part only of the eye, at the distance of half an inch posterior to the margin of the cornea. The lens will fee seen lying on the iris, and beneath its transparent margin, H black circle, which is formed by the ciliary processes. To examine the processes still farther in this section, the lens ma.y be removed, by cutting the posterior part of its capsule. If the parts be ROW put in water, and the proces- ses be scraped with the handle of the knife, the pigment which covers them will be washed away, and then they will have the form of a circle of white stride, projecting front "fr 1 f'horoid. and parking behind the iris. 289 As the retina is a very delicate part, considerable care is requisite in preparing it for demonstration. An ey e should be properly fixed in the saucer, and the chcroid prepared as has already been described ; then, while the eye is under water, a part of the choroid should be torn off, the white opaque retina will then be seen. But there is anoiher coat between this and the choroid, which, however, is so delicate a membrane, that it is almost impossible to see it with the Baked eye; but when the glass globe .is inverted over tku dissection, we shall then see it, floating between the cho Toid and nervous pulp of the retina: this is the membrane; described by Dr. Jacob, of Dublin.* Having seen this membrane, the choroid may be stripped farther off, and then the termination of the nervous matter of the retina will be seen, marked by a vessel, running about the eighth of a.n inch from the margin of thelens.f Some vessels will be seen unclor the nervous matter ; they are on the Tunica Vcisculosa Retince. It may now be understood, that the nervous pulp of the retina, is contained between the membrane of Jacob and the tunica vasculosa. The transparent coats which contain the humours, may now be examined. If we make a puncture in the angle between the margin of the lens and the vitreous humour, and then blow into the puncture, we shall distend the cavity that is called the Pe- tition Canal, and which surrounds the lens. When it is distended with air, or size injection, it has a plaited appear- ance, whence it was called by the French anatomists, Canal Godronnee. Different modes of showing this part, will be described presently. On the plaits, we shall see black stria?, which have erroneously been called the ciliary processes of the retinfE ; they are nothing more than marks left by tho iliary processes ; this appearance, however, gives a good idea of the shape and situation of these processes. J If we make a puncture on the anterior part of the lens, and blow into it, its capsule will be raised ; in doing this. * This membrane was shown to me by Dr. Jacob, while I was on a visit to Dublin, in 1318. Since that time, I b always demonstrated it by the name of Tunica Jacobi, in honour of my friend, who discovered it. f By dropping a little weak acid on the retina, the n- matter will become more distinct ; but if we wash the sur- face with an alkaline solution, the nervous matter will In* destroyed, and then the tunica vasculosa will be seen. | By Winslow, these marks are called S-ulci Ciliarrs ; by ', Corona Ciliaris ; by C. Bell, Halo A a 290 small quantity of fluid, which is called the Liquor Morgag- ni, will escape. By pushing the blow-pipe into the vitreous humour, we may distend the tunica hyaloidea, or capsule of the vitreous humour ; this is not a regular sac, similar to the capsule of the lens, hut has more of a cellular structure, and contains the humour in the cells. This capsule is supposed, by many, to split at the anterior part ; one portion is said to go anteri- or to the lens, the other, posterior to it ; and that, in this manner, the Petitian canal is formed. Mr. Charles Bell. however, has said, in his Description of the Eye, that the canal is formed by the splitting of the tunica vasculosa reti- nsB ; and this he deduces from the examination of the fretal eye, for in it, may be proved, that the vessels of the tunica vasculosa retina?, are continued on the back part of the cap- sule of the lens. But as all these .membranes are exceed- ingly delicate and transparent, in the adult, the manner in which they are connected together, will always continue to be a matter of dispute. If an eye be now so cut, as to allow the lens and vitreous humour to fall out, in connexion with each other, we may again have a good opportunity of showing the Petitian canal : for if we make a puncture in the angle between the two humours, we may distend the canal with any coloured fluid, as red ink: if it be done with size and vermilion, it may be kept as a preparation. The easiest way of doing this, is to suck up a little of the fluid with a glass tube which has been drawnto a point sufficiently fine to enter the puncture, by blowing a very little, the injection will fill the canal. This part may also be easily demonstrated when the eye is slightly putrid, by cutting of the cornea, and about a line of the sclerotic ; we should then tear up the iris, which will separate easily from the ciliary processes ; by then pushing the processes back with the probe, we shall be ena- bled to make a puncture by the side of the lens, into which the blow-pipe is to be introduced ; but if we have not made the puncture in the right place, the capsule of th*> tens, or the capsule of the vitreous humour, will be distended. There is still another transparent membrane, viz. that of the aqueous humour : in some animals, as in the hare, and rabbit, it is very easy to demonstrate it ; but the human eye, and that of the sheep, must be macerated, almost to putre- faction, before this delicate membrane will separate from th<* inside of the cornea. We have now to examine the humours. The Aqur Humour is seen, on puncturing the cornea : it is Described as having two chambers ; one, anterior to the iris. tire 291 r, posterior to it ; but when we cut off the cornea, we shall see that the lens lies almost close upon the iris, so that the space behind the iris, (the Posterior Chamber,) is al- most ideal.* When we take the Lens between our fingers, we shall find, that it is much denser in its centre, than in its circum- ference ; if we boil it, or put it into acid, we shall see this, still more distinctly. When it is boiled, it will have a la- minated form, and when pressed upon, in the centre, it will generally break into three portions. The Vitreous Hu- mour will be found to be a viscid watery humour, contained in a transparent cellular membrane, which gives it the ap- pearance of solid jelly. If we put this humour on a piece of card, and then make two or three holes in the bottom of the card, and, through them, puncture the membrane, the water will escape : then, with a little management, we may blow into the capsule, so as to distend arid dry it. The parts already described, are the principal poins of the anato- my to be attended to ; but if we can procure a very fresh human eye, by making a simple section of it, at half an inch posterior to the cornea, we may discover, near the optic nerve, on the temporal side, the spot described by Sommer- ing, it has the appearance of a hole, with a yellow border surrounding it. But I believe this should rather be consid- ered as a part of the retina, upon which the nervous matter is deficient, than a foramen. If we take the posterior half of the sclerotic, and look upon its inner surface, we shall see the entry of the optic nerve: if we rub the nervous matter off, we shall see a black hole, this is called the porus opti- cus, however, it is only the part at which the arteria cen- tralis retina? enters. By squeezing the nerve from behind, we shall see the pulpy matter oozing at many points, prov- ing, that the nervous matter comes through several forami- na, which form what is called the cribriform part of the scle- rotic, Lamina Cribrosa. In the foetal eye, there are some peculiarities, which i.- be shown by injecting a fcetal calf; the arteria central^ tinte will be seen passing through the centre of the nerve, and through the vitreous humour, to the back part of the cap- sule of the lens, upon which, the vessels run in the form of a spider's web, whence the capsule is sometimes called Tu- jiica Aranea. When the capsule is injected, the ve'ssels of the iris will also be filled. Four distinct arteries pass to the * The size of the two chambers may be shown, by freez- ing the eye, a thin pellicle only, of ice, will be found be- tween the lens and the iris. 292 iris; from the branches of which, vessels.may be seen slioo;- ing across the pupil, in that membrane which is most per- feet in the foetus of seven months, and which is called Mm brana Pitpillaris. DISSECTION OF THE MUSCLES AND LACHRYMAL APPARATUS OF THE EYE- THE parts external to the ball of the eye, may be examin- ed on the body in which the muscles of the face have been dis- sected, By cutting off the orbicularis muscle, and a little cellular membrane which is under it, the cartilages of the eye-lids (Tarsi) will be exposed. . In doing this, we must not lay the upper cartilage quite bare, or we shall be in danger of cut- ting the tendon of the muscle which raises it, Levator Pal- pebrce. By pulling the eye-lids towards the temple, the lig- ament which connects them to the superior maxillary bone, will -be seen. In dissecting this ligament, we must keep close upon it, or we shall open the lachrymal sac. The ex- ternal ligament by which the eye-lids are attached to the t>s make, may be shown, by pulling the lids towards the nose^ The names of External and Internal Canthus are given to these angles of union. Between the union of the eye-lids on the nasal side, there is a little projection called C'aruncula Lachrymali*. It is a prolongation of a fold of this kind, which forms the membra- na nictitons in some animals. The eye-lids are lined by a vascular membrane, which, when the eye-lids are everted, will be seen to be continued over the anterior part of the eye, whence it is named Cojunc tiva, or Adnata. We may now examine the apparatus for the secretion o the tears, and for their passage into the nose. If we pull down the upper eye-lid, and cut the cellular 293 connexion between it and the frontal bone, we shall dis- cover the lachrymal gland. It will be found very difficult to inject the ducts by which the tears pass from this gland into the space between the eye-lids ; but by a careful examina- tion, we may find eight or ten which open upon the inntv surface of the upper eye-lid. When the eye-lids are closed. a little gutter is formed, which conveys the tears to the Puncta,' which are small openings in each eye-lid, on little eminences at the nasal extremities of the cartilages. It is possible to pass bristles into these openings ; and, by a little management, they may be so directed as to pass into the sac which lies in the groove in the os unguis. If this groove be cut upon, the Lachrymal Sac (in which the bristles should be seen") will be opened. It will be found lined with a mucous membrane, and so large that it will ad- mit a common probe, and which, when slightly curved, may be passed from the sac into the duct which carries the teai> into the nose. There is still another secreting apparatus upon the carti- lages : it is composed of a series of small glands, which arc named, in compliment to the anatomist who first described them, Jlfeibomcan. When the eye-lids are everted, the glands will be seen in parallel rows, like a number of small ascarides, on the surface of the cartilages, and under th' conjunctiva. Each of them opens on the margin of the eye- lid by a separate duct. It is the inflammation of one of thcsf small glands which causes the common disease called Stye. In making the dissection ofthe eye-lids, we can easily un- derstand the two common diseases, ectropion and entropion. In the worst case of ectropion, it is necessary to cut out a portion, and unite the edges ofthe incision, so as to make the. lid shorter. In the entropion, an operation must be per- tonnedthat will make the lid longer ; a simple snip through the lid, which will be filled up by granulation, will sometimes be sufficient for this. The necessity of great care in remov- ing small tumours from the eye-lid, must be evident, when we examine the cartilages. I have seen a patient, on whom the operation of ectropian had been performed, by extracting the cartilage ; the consequence was, that the eye was near- ly destroyed by the constant pressure ofthe oibicularis mus- t.*le. The muscles of the eye should now be dissected^. Wt? should cut through the eye-lids at their two points of union, and then separate the lower eye-lid from the ball ofthe by dissecting the conjunctiva from its union to the-ball ; we may then cut off this eye-lid. We should separate the per eye-lid in the same manner; but we must not e\ A a '2 ' 294 away, as the levator palpcbrse must yet be dissected. It is difficult to disscet all the muscles without cutting par? of the frontal and malar bones; but if we are desirous of pre- serving the scull, we must do as well as We can in the nar- row space. To make a fine display of the muscles (if the scull has not been opened) we should cut through the as- cending orbital process of the os malie, to the depth of au inch, in a line with the floor of the orbit, and then cut the ex- ternal angular process of the frontal bone, commencing ia the superciliary ridge, and carrying the cut down so as to meet that on the os malse. If the scull-cap has been removed, the dissection may be made still more easy by cutting away the roof of the orbit : but in doing this, we must not come upon the foramen, nor nearer to the internal angular process than the supercil- iary hole : for if we break up the optic foramen, we shall destroy the origin V)f the muscles ; and if we cut down the internal angular process, we shall cut through the pully of the trochlearis* The first muscle to be dissected, is the only one which does not arise from the foramen opticum, the Obliquus In-- ferior, or Externus. To stretch its fibres, we should puU the ball of the eye towards the temple, for this muscle arises- from the bone, above the inferior orbital foramen, and is h> serted into the outer part of the ball of the eye. Before dissecting the muscles which pass from the fora- men opticum to the ball of the eye, we should pull down the remaining part of the upper eye-lid, and dissect the muscle which lies immediately under the roof of the orbit, viz. the Levator Palpebrce. Having dissected this, the eye-lid and muscle should be removed. The whole of the dissection now consists in removing the loose fat which is between the ntuscles. We shall find the Superior Oblique, or Troche! aris, lying upon the os planum : its tendon, after running through a small ligamentous and cartilaginous band (which is attached to the lower part of the internal angular process,) passes backwards, below the rec- tus superior, and is inserted into the ball of the eye, about its middle and upper part. There are no particular directions necessary to enable tho student to dissect the four recti muscles ; for they run direct irom around the foramen opticum, to the ball of the eye, 4 heir combined tendons forming, on the anterior part of the ball, an expansion of tendinous membrane, which is describ- ed as a coat, common to the ball of the eye and to the mus- des ; it is called the Tumca Albuginea, The muscles of the eve maveasilv be recollected, for there 295 nly seven in all ; of which, six belong to the ball of tii< eye, and one belongs to the upper eye-lid. The muscle of the eye-lid is called Levator Palpebrce Superiorly. It arises from the. upper edge of the foramen opticum, and is inserted into the cartilage of the eye-lid. The six muscles are divi- ded into the Four Rectia.nd the Two Oblique. The four reo ti are distinguished from each other by the terms Levator. Depressor, Mductor and Adductor : while the two oblique are named, the "one, External or Inferior ; the other, Inter- nal . or Superior ; or, from its passing through the pully, Trochleari*. All the four recti arise from around the foramen opticum, and are inserted into the sclerotic, at nearly equal distances from the cornea. The internal oblique also arises from the edge of the foramen opticum; its course and its insertion have already been described. The external oblique cannot be forgotten, as it is the only muscle which arises from the outer edge of the orbit. The dissection of the nerves of the orbit has already been described at page 269. The dissection of the arteries maybe made at the same time that those of the brain are examined ; and as the dis- section consists in merely following them from trunk to branch, I shall give only a Table of them : OPHTHALMICA CEREBRALIS. Passing into the orbit, by the foramen opticum, gives these branches : To the dura mater and'sinus ; 2. lachrymalis, which goes to the gland, after giving many branches to the periosteum, optic nerve, &c. ; 3. ciliares ; three or four arterie.s. dignified with the distinction of inferiorcs, anterior es, breves, longiores ; 4. supra orbitalis ; 5. centralis retina* G. aethmoidales ; 7. palpebrales ; 8, nasalis ; 9. fron-- talis. METHOD OF MAKING CERTAIN PREPARA- TIONS OF THE EYE. It will be very useful to preserve some human eyes, to show the relative situation of the parts : for this purpose : the eyes must be very fresh. A student will find it difficult to imitate some of the pre- parations which are preserved in anatomical museums : but any one may make suck dissections, as will give a general idea of the anatomy of the parts, and be of use in planning operations on the eye. If we remove all the muscles, &r. from the eye-ball, and cut off about one third of the cornea. 296 raid then insinuate the blade of the scissars between the ary ligament and the sclerotic, that we may cut oft* about a third of the sclerotic, the c'horoid, and its connexion with the iris, will be shown : this forms a very good preparation. Another eye may be prepared, so far in the same manner ; it is to be completed, by cutting away the portion of the cho- roid corresponding to the sclerotic, so as to expose the reti- na ; but in attempting to do this, we shall often be foiled. A third preparation may be made, nearly in the same man- ner ; but in it, we should remove the retina. This last preparation will be very useful ; for not only wiH one half of the cornea, the size of the anterior chamber, fhe ligament-urn ciliare, the iris, and the pupil be shown, but also the situation of the lens and ciliary processes, and the vitreous humour, will all be distinct]} 7 seen. As soon as such a dissection is made, the eye should be put into proof spirit. By this, however, both the lens and the capsule of the vitre- ous humour, will be made opaque. The view of the parts in this section, will prove, that oc* enlists who say they have put the cataract into the posterior chamber, must be ignorant of anatomy. The proper place tor the introduction of the needle, in couching, so as to avoid the ciliary processes, will be evident. In considering tin/, subject of couching, there is a point of great importance, which maybe understood in the dissection of even a sheep's eye, viz. the possibility of the lens and vitreous humour be- ing both turned round in the attempt to couch. When thi,< happens, total blindness may be the consequence, as the ner- vous matter of the retina may be destroyed by the displace- ment of the vitieous humour. SURGICAL DISSECTION, JYECK dJVD HEAD THERE are so many important questions connected wiiis the Surgical Anatomy of the neck and head, that it would be impossible for me to enter fully into any one ; all that the 297 limits of a book of this land will permit, is, to make such re- marks, as will rouee the student's attention to the importance of the subject. I shall suppose that the student has made himself master of all the muscles, arteries, nerves, &c. and that he is now about to make a dissection of the neck, as a part upon which he may be called on to operate, or to give an opinion as to the- nature and connexions of a tumour. The vessels should not be injected.* Previous to beginning the dissection, the student should mark all the prominent points with ink ; he should then vary the position of the head and neck, and compare the chann the sheath and the muscle. Bb 302 tlielic nerve lies close on the spine, and quite/ separated from the general sheath of the vessels. In making this dissection, we must not forget that the head is lying in a very different position from that of a pa- tient on whom an operation is to be performed. As the pa- tient will probably be sitting-, with his head reclining on a pillow, we ought to elevate the neck of the subject into that position.- The manner in which the artery is 'here advised to be tied, is nearly the same as that which is given, in the illustrations of the Grand Operations of Surgery, by Mr. Charles Bell. It differs considerably from the manner of operating recommended by Mr. Cooper, and by several other Surgeons. But before such a serious operation is perform- ed, I would recommend the operator to read every thing that has been written on the question, and to compare the several modes proposed. Many interesting cases will be found in the Medico- Chirurgical Transactions, related by Mr. Cooper, Mr. Dalrymple, Mr. Vincent, and Mr. Coates": and also many excellent remarks on the principle of the op- eration, in the illustrations of Surgery, by Mr. Bell. At the place just pointed out, the artery may be cut down upon, so as to be compressed between the linger and thumb, or tied, when a very severe operation is to be per- formed below the angle of the jaw. It is hardly necessary to consider how the carotid should be tied, when cut by the suicide ; for when it is opened by a large incision, the patient will probably be dead before the surgeon is brought to him ; but still, such a question rnay offer. Mr. John Bell tied i! one case, with success ; but the circumstances were peculiar, for the unfortunate person wa* so cool, and so determined to commit suicide, that after having read the description of the artery, in Mr. Bell's Work on Anatomy, he stood before a mirror, and calculated the situation of the carotid so nicely, as to pierce it with a pen- ! jorife; but in consequence of the small size of the external orifice, the haemorrhage was not very great, the external . wound closed, and an aneurism formed, lor which, Mr. Bel] performed the common operation.. The necessity of making ourselves intimately acquainted with the bearings of this artery, \vas strongly impressed up- on- me, Eome years ago, by a surgeon relating a case to me, where, after a stab in the neck, there was repeated ha?morr- hage : on saying to him, Why did you not tie the carotid ': with a most significant shake of his head, he replied, " Catch me at the carotid !" But the times are now altered ; for, that it is not now considered a difficult operation to tie this' artery, is proved, by some, surgeons having ^ven trirr 1 303 iinont of tying it for head-ache, and fur tumours, Ov but it is to be hoped, that even the great ease with which the artery maybe found, will not induce us to repeat any of fhose experiments. We may now prosecute the dissection towards the an-. of the jaw, and consider the manner of securing the vessels, when cut at the root of the tongue, by the suicide. We see the larnyx and the sterno cleido mastoideus pro- tect tho carotid, and that the branches most exposed, aiv those of the lingual and facial arteries. The cornu of the OH hyoides should be carefully marked ; for this is the part which we should feel for, as a guide, by which we shall ea- sily find. the lingual and 'facial arteries. The vessels will generally be easily secured in the wound made by the sui- cide ; for, there will be a large open incision, and before we are brought to him, the quantity of blood lost, will have di- minished the arterial force. In some cases, it maybe diffi- cult to tie the arteries neatly. I have been obliged, in sc- c jndary haemorrhage under the tongue, to pass a needle and ' uread coarsely round a bleeding surface. This was against ile; but I was forced to do it, because the state ofth< parts was such, tiiat I could not discover the bleeding ves- sel, and as the source of the hsemorrliage was exactly in the middle of the throat, I was afraid, that if I tied one caro- tid, I should be obliged to tie the other also; and that, even if J tied the carotid from which the vessel arose, there would still, from the anastomosing vessels, be bleeding suf- ficient to destroy a jmtient who had already, for the second time in six days,, lost two pounds of arterial blood. The pa- tient did well. We have now brought the dissection up to the angle of the jaw ; and here comes the very important question of extir- ,11 of tumours. In dissecting up the platysma, we exposed parts of the maxillary, and parotid glands ; under the margin of the submaxillary, and sometimes within its substance, we shall ihi'l a small lymphatic gland, when this becomes diseased, and grows large and hard, it presses up the submaxillary gland, so as to give it the appearance of being affected ; and thus we have narratives of the extirpation of the submaxil- lary, when, most probably, the disease has been only in the lymphatic gland ; for the salivary glands are very seldom scirrhous. The dissection will show, that an encysted tu- mour may sometimes betaken out, without much haemorr- hage. In such a case, we should first mark the situation of 1 he facial artery and vein, and, voiding them, make an inci- on the edge of the submaxillary gland, so that we m >y .304 lift up itsejge, and scoop out the tumour ; but if it be very hard, and adhering to the gland, then we may have con- siderable bleeding, but not necessarily dangerous ; for it will probably be from the facial, or lingual artery, and either of these arteries may be tied, the cornu of the os hyoi- above it, and the facial a little higher. We must not for- get that the lingual nerve is situated between these vessels. These remarks upon the liability of a scirrhous lymphatic being mistaken for disease of the salivary gland, apply more forcibly to the tumours which are connected with the paro- tid. Every student who examines the anatomy of the paro- tid gland, and, particularly when it is injected with quick* silver, will suspect that the histories of operations, in which a diseased parotid is said to have been wholly extirpated, are erroneous. The external carotid artery passes through the substance of the gland, but this is no objection to the accuracy of the report ; for it maybe tied both above and below; but, is there no danger of cutting the internal caro- tid, or the internal jugular, or the par vagum, in the attempt to extirp ite those parts of the gland which are situated so deep as the space between the occuput and atlas ? These considerations induce me to believe, that we cannot extir- pate the parotid gland. It is frequently necessary to cut off a portion of the paro- tid, when a scirrhous tumour is imbedded in it : in these op- erations, the blood issues as from a sponge, so that it is very difficult to find all the vessels ; but in the greater number of cases, the graduated compress will restrain the bleeding from the smaller arteries. If We must tie the external caro- tid previous to such an operation, we may proceed thus : If we cut through the skin, from the lobe of the ear, towards the cornu of ihe os hyoides, and then dissect through the platysma myoides, we shall come upon the digastric ; and if we then dissect along the upper edge of this muscle, we shall expose the stylo hyoideus, by forcing this last muscle* downwards, we shall find the continued trunk of the exter- nal carotid. In extirpating tumours from this part, we must cut across many branches of the portio dura,* which will cause partial paralysis of the face. * Since the use of the portio dura has been illustrated by the facts of comparative anatomy, and by various experi- ments instituted by Mr. Bell, we have been able to explain many symptoms of disease, which have hitherto puzzled eur- 305 v The dissection of the duct of the parotid should now bo made, and its situation accurately marked, that we may avoid That I may direct the student's attention more particular- ly to this subject, I shall mention one or two cases, which are illustrative of the consequence of an injury to this nerve. In a case of cynanche parotidea, where suppuration took place, every muscle to which the portio dura went, was pn - ralyzed in the act of respiration, or expression ; but the samr muscles were still efficient in the act of mastication : thus., when the patient attempted to whistle, or when he was made to sneeze, the muscles of only one side acted, but when he chewed his food, the muscles of both sides were in full action. This paralysis continued for a considerable timo after the sinuses were healed ; I then lost sight of the pa- tient. A slight degree of paralysis of one side of the face, is of- ten seen in young people. Such cases we have generally been able to trace to an inflamed gland below the ear. J was lately consulted in a very interesting ease, nearly of a similar nature. A young lady had, for several years, a dis- tinct twist of one side of her mouth, particularly when she smiled ; but of late, she has had an affection of her eye-lid. As she was under the care of a gentleman who was acquaint- ed with the experiments which we had been making in Windmill-street, the cause of the twist of the mouth was, by hinvcorrectly referred to a severe attack of inflammation, which the lady had had some years ago ; but as he found it. difficult to understand why the eye should be also now affect- ed, he begged that I would see the patient with him. On noticing the action of the muscles, which I did while the lady was sitting at luncheon, I observed that no act inn was deficient while she was eating, but that there was a dis- tinct paralysis when she smiled or laughed ; however, I was a little- puzzled to see the muscles of the mouth so distinctly affected, and not those of the eye ; because I had found iii all the experiments in which the portio dura was cut, and in the cases where the paralysis had been produced by an in- flamed gland under the ear, that both the muscles of the eye and of the mouth were affected at the same moment. But on farther inquiry, tho cause of the difference in this casf. was explained ; for I found that the inflammation which had been the original source of the injury to the nerve, was con- lined to the space above the molar teeth, so that the branch- .es of the nerve which go to the muscles round the eye, wero not included in the disease. The twitching of the eye-lki was quite different from that of the muscles of the mouth 306 it during the operations on the face. We shall find that a line, drawn from the middle of the tube of the ear to the opening of the nostril, will generally be immediately oven the duct ; but though we may mark its situation pretty accu- rately, we shall proceed with less dread in removing a tu- mour that is situated near it, if, instead of trusting to our recollection of the situation of the duct, we pass a fistula lachrymalis probe, into it : this may be easily done by averting the cheek ; for the opening of the duct will be found opposite to the second molaris. The bleeding, in most operations on the face, will be com- manded by the assistant pressing on the facial artery, where It was only that slight spasmodic affection which is so com- mon in hysterical girls, and would not have been noticed, had it not been supposed to have some connexion with the state of the mouth. This young lady told me, that, to a cer- tain degree, she could command the action of the muscles ; but, that she found it impossible to overcome it on her entry into a room where she was obliged to accost strangers. There are certain tumours under the ear, which are of so :;^e 278, we may understand how a tube may be p;> from the nose into the larynx; how a polypus hanging- down from the posterior nostril, may produce suffocation ; how il may be possible to restrain a violent haemorrhage from the nose, by plugging up the posterior nostrils. We may now understand how much the ethmoid bone. ;.? nd even the brain, may be endangered by the forcible ex-- traction of the polypi. The principles upon which the dif- ferent operations of fistula lachrymalrs are to be performed, may be seen. We shall also be able to determine upon the most favorable position of tho head, in cases where there is a collection of matter in the antrum ; and by pulling the se- cond molaris, we shall see that a free exit might be given to matter collected in that cavity. We may perform the operation of trephine upon the sub- ject, with much advantage; for we may make examples of the various fractures which require operation, and at the .same time see the greater number of difficulties which may occur daring the operation on a patient. If we allow the head to fall on the ground, we shall probably produce simple fracture^ with extensive fissure ; if we strike it a smart blow with a hammer, we shall per- haps produce a stellated fracture ; in such a case as this, wo may, with small levers and forceps, pick away the piece's of bone, without using the trephine. When the scull is struck with a sharp point, though there will be only a depression or hole in the external tables, yet there will probably be an ex- tensive fracture of the tabula vitrea ; this, it is evident, will require a large trephine. If the head be allowed to fall on the vertex, or if it be struck with a heavy body, as when a brick-tfat falls from a building on the top of the head, we may find that the fracture has taken place at one, or both, of the temples. In performing the operation, we should pay particular a-t- fention to the various degrees of thickness in the different parts of the scull. In a rickety person, we may expect that, at certain points, the scull will be very thick. As we shall . find that, in the greater number of sculls, there are no marks by which we *can be guided in judging of the thickness, we shall be satisfied of the justness of the rule, that, the opera- tion of trephine should always be very cautiously performed. There are certain points, which a dissector, who had not. seen much practice in surgery, would be afraid to set his tre- phine upon, as, for example, in the course of the longitudi- nal sinus; but experience shows, that there is no danger in opening the scull here. The manner in which the meningea media frequently runs in the substance of the bone, will 311 to us, that in the greater number of cases wheiv trephine is applied over its course, it must be cut ; but this frhould not alarm us, for when the artery is cut, the bleed- ing- can be easily stopped. The practical surgeon will agree with the dissector, in Considering it very difficult to apply the trephine over the irontal sinuses, or in the line of the spine of the os frontis. When the external table of the frontal sinus is removed, wo can understand how the membrane lining it, has, in ecme op- erations, been mistaken for the dura mater. By striking the scull smartly with a mallet, the dura ma- ter will be detached from the bone, at the part struck : if UK* head be afterwards injected with size, a coagulum will be found at this part. This experiment would lead us to d< the accuracy of Mr. Abernethy's explanation of the cau.-e of effusion of blood between the dura mater and the bone. While the student has these parts before him, he should read the Works of Pott, John Bell, and Abernethy, and oi" Charles Bell ; in the Fourth Number of the Surgical Obser- vations, by Charles Bell, he will find many remarks applies ble to the question of the varieties of fracture. DISSECTION OF THE ARM, AFTER IT IS SEPARATED FROM THE BOD\ THE dissection of the muscles by which the arm is attach "d to the body, is described at pages 199 and 2^9. The first muscles to be dissected, are those surrounding the shoulder joint.* A block should be put under the joint, o as to make the fibres of the principal muscle, the Deltoid, tense. We shall find that the cellular membrane and fal pass to such a depth between the fibres of this muscle, that * In the first dissection, every thing is to be cur. a^\ oopt the muscles. 312 ?ho knife must be set on very boldly, before we can make it appear clean. After the origins and insertion ofthe muscle have been shown, the tendinous fascia by which it is con- nected to the base of the scapula, is to be dissected up, so as to expose the muscles w T hich are below the spine of the scapu- la. This -mass appears at first to be formed by one muscle only ; but by looking near to the lower costa ofthe scapula, a line of division will be seen in it, which separates the Teres Minor from the Infra Spinatus ^ both of which may be traced to the great tubercle on the head ofthe humerus. On the lower edge of the teres minor, a distinct and large muscle, viz. the Teres Major, will be seen running from the inferior angle of the scapula to the humerus, to be inserted along with the latissimus dorsi. The origins of the deltoid, from the clavicle, acromion, and spine of the scapula, must now be raised. A small part ofthe muscle may be left attached to the humerus. A set of fibres will now be seen, occupying the space which in above the spine of the scapula,* and which pass under the acromidn, to the great tubercle on the head of the humerus ; these form the Supra Spinatus muscle. At the edge of the notch, we may observe the origin of the small muscle which passes to the neck, viz. the omo hyoideus. We may now turn to the lower surface ofthe scapula. The loose portion, which will probably appear ragged and slightly putrid, is a. part of the serratus major anticus : when this, with the cellular membrane which is below it, is dissect- ed off towards the base ofthe scapula, the Subscapularis will be exposed. This muscle will be found to occupy all the concave surface of the scapula, and to be inserted into the lesser tubercle ofthe humerus. We may now pass to the dissection of the muscles which lie on the hurnerus. The first muscle to be dissected on the forepart, is the Coraco Brarkialis ; the fibres of which run in a straight line from the coracoid process to the inside of the humerus. In expos ng the fibres of this muscle, those ofthe short head of biceps will also be shown. The belly of the Biceps is covered by a thin fascia, which is to be raised, by cutting in the direction ofthe fibres. When near the bend ofthe arm, we must be careful not to cut through the band of fascia which passes off from the edge ofthe biceps ; for this is an attachment which the muscle has with the fas- cia that covers those of the fore arm. The insertion ofthe biceps into the tubercle of the radius, cannot be shown until * Perhaps a part of the trapezius may still be attached to the clavicle and spine ofthe scapula : this should be rem<>v 313 !he muscles of the fore arm are dissected; nor should \Vf: at present, cut the capsular ligament of the shoulder joint-. ~to expose the origin of the long head of the biceps from the glenoid cavity. The Brachinlis Intcmus may be seen under the biceps. As the fibres of this muscle run nearly parallel to the bone, there can be no difficulty in showing them in their whole extent, iYom their origin on the humerus to their insertion into the coronoid process of the ulna. The large mass of muscle which is on the back part of the arm, forms the Triceps Extensor : it is merely necessary to look to the direction of the fibres of the three different heads, to enable us to dissect them down to their union and insertion into the olecranon ; but in dissecting the lower part of this muscle, we must not confound it with the Anco* #Mtf, which passes from the external condyle to the ulna. Before dissecting the muscles of the fore arm, the fascia which binds them together should be exposed : this is most easily done, by commencing the dissection at the outer part of the arm, and carrying it towards the inner. The dissec- tion should be continued to the wrist ; and then the several muscles which compose the first layer may be seen through the transparent fascia. The only rule necessary to be re- collected in the dissection of these muscles, is to remove the cellular membrane in the direction of the fibres. For their arrangement, and their origins and insertions, see page 317. The muscles of the hand are rather difficult to dissect, in consequence of their connexion with the palmar aponeuro- ais. This fascia ougnt to be exposed before we begin to dis- sect the muscles. The incision should be made in the mid- dle of the hand, from the annular ligament to the middle finger. The skin is to be carried towards the thumb, and towards the ulnar side of the hand. But in cutting in the last direction, we must take care that we do not dissect off the little muscle, Palmar^ Brevis, which is attached to the dkin for about an inch below the pisiform bone : indeed, this muscle should be exposed before the fascia is dissected. CLASSIFICATION OF THE MUSCLES OF THE ARM. It is hardly possible to arrange the muscles moving 1 tlu? .humerus, into classes which shall have each a distinct action to perform, in consequence of the motions of the humeru?. on the scapula, being so varied. Perhaps the following enu- meration will assist the student in recollecting them : The muscles which are inserted into the upper part. mu>* c 314 raise the arm : thus the supra spinatus, infra spinafats, and leres minor, being inserted into the great tubercle, are of this class : so is the delioides, which is also inserted into the upper part of the arm, but further from the head. There is only one muscle inserted into the lesser tubercle, the subscapularis, and which must pull the s^rm backwards and downwards. Two muscles are inserted into the outer edge of the bicip- ital groove, the pectoralis major and coraco brachialis ; and these must pull the arm inwards and forwards. The two muscles which are inserted into the outer part of the bicipita] groove, will pull the arm backwards, viz. the la- Ussimus dorsi and leres major. TABLE OF THE ORIGINS AND INSERTIONS OF THE MUSCLES MOVING THE IIUMERUS.* MUSCLES OF THE SHOULDER LYING ON THE SCAPULA. SUBSCAPULARIS. OK. 1. All the base and hollow of the scapula internally. 2. Its superior arid inferior costae. IN. The upper part of the internal or lesser protuberance on the head of the humerus. SUPRA SPINATUS. OR. 1. From all that part of the base of the scapula which is above its spine. 2. From the spine and superior costa. 3. From the fascia of the scapula. IN. The part of the larger protuberance on the head of the os humeri that is next the groove. INFRA SPINATUS. OR. 1. All that part of the base of the scapula which is between its spine and inferior angle. 2. The spine, as far as the cervix of the scapula. 3. The fas- cia of the scapula. IN. The upper and middle part of the large protuberance on the head of theos humeri. TERES MINOR. OR. From the inferior costa of the sca- pula, extending from the neck to an inch and a half from the inferior angle. IN. The back part of the large protuberances on the head 6f the os humeri. TERES MAJOR. OR. 1. The inferior angle. 2. Inferior costa of the scapula. * The origins and insertions of the latissinnis dor>i and pectoralis, are described at pages 229 and 109* 315 IN. The rulgc at the inner side of the groove for umy im- f|te tendon of the long head of the biceps (along with the fS&don of the latissimus dorsi.) DELTOIDES. OR. From the outer part of the clavicle. 2. From the acromion. 3. From the lower margin of almost, the whole spine of the scapula opposite to'the insertion of the cucullaris muscle. IN. A rough protuberance in the outer side of the os hu- ihen, near its middle. USE. Its centre raises the humerus, the lateral portions sustain the shoulder joint. CORACO BRACHIALIS. OR. The coracoid process of the scapula, adhering in its descent to the short head of the bi- ceps. ^ IN. The middle of the internal part of the os humeri, near nie origin of the third head of the triceps. USE. To raise the arm upwards and forwards. The muscles which move the fore arm are exceedingly smple ; as the form of the joint between the humerus an*d bones of the arm, is such as to admit only of two motions, viz. flexion and extension. The flexer muscles are two, tticeps and Brachudis Internus ; the extensors are also two, ?'riceps and Jlnconcus. TABLE OF THE MUSCLES WHICH MOVE THE FORE ARM ON THE HUMERUS. FLEXORS. BICEPS FLEXOR CUBITT. OR. By two heads.- I . Tendinous, from the upper edge of the glenoid cavity of the scapula. This tendon passes over the head of the os hu- mcri within the capsule, and, in its descent without the joint, runs in a groove on the head of the 6s humeri. and covered by a membraneous ligament that proceeds "from the capsule and adjacent tendons. 2. The second, and shorter head, arises from the coracoid process of the scapula, in common with the coraco brachialis muscle. IN. 1. By a strong round tendon, into the tubercle near the upper end of the radius ; 2. and, by a lateral slip of fas- cia, into the sheath of the fore arm. BRACHIALIS INTERNUS. OR. The middle of the os hu- meri, at each side of the insertion of the deltoid muscle, cov- ering all the inferior and fore part of this bone ; adheres te the ligament of the joint. IN. The coronoid process of the ulna. 316 EXTENSORS. -TRICEPS EXTENSOR CUBITI. On. By three heads ; the first and longest, from the inferior costa of the scapula, near its cervix. The second head, from the back part of the os humeri, under the great tubercle. The third* arises by an acute beginning from the back and inner part of the humerus, and continues its origin all down the bone. These three heads unite lower than the insertion of the teres major,* and cover the whole posteriar part of the hume- rus ; from which they receive additional origins in their de- scent. IN. The olecranon, and partly into the condyles of the os humeri, adhering to the ligament. ANCONEUS. OR. From the back part of the external con- dyle of the os humeri ; it soon grows fleshy. IN. A ridge on the outer and posterior edge of the ulma.. being continued some way below the olecranon. It is cover- ed with a strong fascia. The muscles lying on the fore arm, are generally consid- ered very difficult for a student to understand ; perhaps the following plan of arranging them in numbers, will obviate some of the difficulties. If we take the biceps flexor as a .supinator, which it truly is, and the mass of the flexor mus- cles (on the fore arm) as one great pronator, for such is their conjoint operation, then the muscles will go in threes, thus : For the .motion of the wrist, three flexors, the ulnari&, mdialis, and medius (commonly called palmaris longus) ; three extensors ulnaris^ radiatu, longior, and brevior : three pronators, the teres, quadratus, and the mass of the .flexor muscles ; three supinators, the supinator longus t brevis, and biceps cul-iti. There are three extensors of the fingers, viz. extensor com- munis digitoruify extensor primi digi/i, and extensor minimi digiti; three extensors of the thumb, extensor primus, sc'cimdus, and terlius ; three flexors of the fingers and thumb, -flexor digitorum, sublimis, flexor digitorum profun*- d us, flexor pollici-s longus. In describing the muscles of the fore arm, it is nearly cor- rect to say, that the flexors and pronators arise from the in- ner condyle, and the extensors and supinators from the outer * The third head is sometimes called brachialis internu^ and then the two first heads arc described as forming a &K r eps extensor. 317 ondyle : but the supinators and pronalors will be more pro- perly distinguished by their insertions, as all muscles which turn the hand must be inserted into the radius : as for exam- ple, the wpinator longus, the supinator brevis, the pronator icrcS) the pronator quadratus. TABLE OF THE MUSCLES LYING ON THE FORE ARM. FLEXORS OP THE WRIST. FLEXOR CARPI RADTALIS. Oa. The internal cpndyle oj' the os humeri, and from the fore and upper part of the ulna. IN. The fore and upper part of the metacarpal bone that sustains the fore finger, runs over the os trapezium. FLEXOR CARPI ULNARIS. OR. The internal condylu oi the os humeri, and side of theolecranon, and from the fascia- IN. The os pisiform, and ligament of the wrist. FLEXOR CARPI MEDIUS, OR PALMARIS LONGUS. OR. The internal condyle of theos humeri, from the intermuseu- lar ligament : it forms a neat small belly, and by a long slen- der tendon, has IN. Into the annular ligament of the wrist, and palmar aponeurosis. EXTENSORS OF THE WRIST. EXTENSOR CARPI RADIALIS LONGIOR. OR. From the low - er part of the external ridge of the os humeri, above its ex- ternal condyle, and below the supinator radii longus. IN. The back and uppar part of the metacarpal bone that sustains the fore finger. EXTENSOR CARPI RADIALIS BREVIOR. OR. 1. the ex- ternal condyle of the os humeri ; 2. the ligament that con- nects the radius to it. IN. The upper and back part of the metacarpal bone that sustains the middle finger. EXTENSOR CARPI ULNARIS. OR. 1. The external con- dyle of the os hurneri ; 2. the ulna, from its posterior bor- ber. IN. 'The posterior and upper part of the matacarpal bone that sustains the little finger. > MULCLES OP SUPINATION AND PRONATION. PROPER SUPINATORS ; that is, those which turn t af the hand upward, and have no other office. 318 SUPINATOR RADII LONGUS. OR. The external ridge of the os bumeri, nearly as far up as the middle of that bone. IN. The lower end of the radius, on its outer side. SUPINATOR RADII BREVIS. OR. 1. From the external condyle of the os humeri ; 2. from the external, and upper part of the ulna ; 3. the ligament which joins these two bones. IN. The neck and tubercle of the radius, and ridge run- ning downwards from the tubercle. PRONATORS ; that is, which throw the palm of the hand prone to the ground. PRONATOR RADII TERES. OR. 1. The internal condyle of the humerus ; 2. tendinous from the coronoid process of the ulna. IN. The outside of the radius, about the middle of the bone. PRONATOR RADII QUADRATUS. OR. The lower part of the ulna : the belly of the muscle runs transversely. IN. The lower and outer part of the radius. MUSCLES MOVING THE FINGERS, LYING ON THE FORE ARM. FLEXOR SUBLIMIS PERFORATUS. OR. 1. The internal eon- ilyleof the os humeri; 2. the coronoid process of the 'ulna; 3. the tubercle of the radius; 4. the middle of the fore part of the radius, where the flexor pollicis lorigus arises. The tendons pass under the ligament of the wrist. IN. The second bone of each finger, being, near its ex- tremity, divided for the passage of the tendons of the per- forans, or profundus. FLEXOR PROFUNDUS PERFORANS. OR. 1. The side and upper part of the ulna; 2. from a large share of the interos- seous ligament, and remotely through the fascia from the inner condyle ; its tendons pass under the annular ligament of the wrist, and then pass through the slits in the tendons '.f the flexor sublimis. IN. Last bones of the four fingers. FLEXOR LONGUS POLLICIS MANUS. OR. 1. The side of f he coronoid process of the alna ; 2. the radius, immediately below its tubercle ; it is continued down for some space on Ue fore part of the bone ; 3. the interosseous ligament: its- " pfldon passes under the ligament of the wrist. It has an 319 rigin, frequently, from the internal eondyle of the os humeri. IN. The last bone of the thumb. EXTENSOR MUSCLES OF THE FINGERS AND THUMB* EXTENSOR DIGITORUM COMMUNIS. OR. 1. From the < 'xternal condyle of the os humeri, where it adheres to the supinator radii brevis. Before it passes under the ligamen- turn carpi annulare externum, it splits into four tendons, some of which may be divided into several smaller. On the back of the hand, the tendons are often united by inter- change of tendinous filaments. IN. The posterior part of the bones of the fingers, by a tendinous expansion. USE. To extend all the fingers. EXTENSOR MINIMI DIGITI. OR. The external condyle ; the fascia of it adheres to the common extensor. IN. The last bone of the litttle finger. INDICATOR, OR EXTENSOR PRIMI DIGITI. OR. The mid die of the back part of the ulna ; its tendon passes under the same ligament with the extensor digitorum communis, with ' part of which it is IN. Into the posterior part of the fore fing'er. EXTENSOR PRIMI INTERNODII POLLICIS MANUS, VEL Os- sis METACARprPoLLicis. OR. 1. The middle and poster! or part of the ulna, immediately below the insertion of the a.nconeous muscle ; 2. the back part of the middle of the radius ; 3. the interosseous ligament. IN. (By two tendons) into the os trapezium, and uppci back part of the metacarpal bone of the thumb, and often joins with the abductor pollicis. USE. To draw the metacarpal bone of the thumb out- wardly. EXTENSOR SECUNDI INTERNODII. OR. 1. The back parf of the ulna, near the former muscle ; 2. the interosseous liga- ment. IN. The posterior part of the first bone of the thumb : part of it may be traced as far as the second bone. USE. To extend and draw the "second bone of the thumb outwards. EXTENSOR TERTII INTERNODIT. OR. 1. The middle and back part of the ulna; 2. from the interosseous H its tendon runs through a small groove, at the inner back part of the lower end of the radius. IN. The last bone of the thumb. USE-. To extend the last joint of the thumb. 320 The variety of motions which we are enabled .to execute with the fingers, is sufficient evidence of the complication of the small muscles which lie on the hand. If we first make an arrangement of the muscles which move the thumb, and those which move the little finger, there will not be much difficulty in recollecting the other muscles. We find a muscle for pulling the thumb from' the fingers, Abductor PoUicis: one for drawing the thumb towards the fingers, Adductor Pollicis : and to .bend the thumb, Flexor Hrevis: with this muscle may be classed the one called Opponent) of Flexor Ossis Meiacarpi Pollicis. For the little finger we have an Abductor, Adductor, and Flexor. There still remain the small muscles which bend all the fingers, viz. the Lumbricales. There is also a set of muscles which lie between the metacarpal bones ; these are called Interossei Externi and Intcrni ; the use of which, is, to draw the fingers separate .- with this class may be arrang- ed the muscle called Abductor Indicis ; as it lies between the metacarpal bone of the fore finger, and that of the thumb. There is one muscle omitted in this arrangement, be- cause it stands by itself, the Pa'maris Brevis ; being the >et of fibres which were seen on the palmar aponeurosis, and covering the muscles of the little finger. TABLE OF THE MUSCLES OF THE HAND. ' PALMARIS BREVIS. On. The ligamentum carpi annu- !aro, and tendinous membrane that is expanded on the palm of the hand. IN. Into the skin and fat that cover the abductor minimi digiti, and into the os pisiforme. "USE. To assist in contracting the palm of theha'nd: to sustain the grasp of the hand. MUSCLES WHICH FORM THE BALL OF THE THUMB. ABDUCTOR POLLICIS. OR. The os trapezium : and liga- ment of the carpus. IN. Root of the second bone of the thumb. USE. To separate the thumb from the fingers. OPPONENS POLLICIS. (Under the last.) OR. Os trapezium, and ligament of the carpus. IN. First bone of the thumb, or, metacarpal of the thumb, as it is sometimes called. I T ?E. To bring the thumb towards the palm and fingers- 321 PLEXOR BaEVia POLLICIS. (Divided by the tendon of tin* long 1 flexor.) OR. 1. Os trapezoidee; 2. os magnum; 3. os unciforme. IN. Ossa sesamoidea, and second bone of the thumb. USE. To bend the thumb. ADDUCTOR POLLICIS. OR. From the metaearpal bone oi' the middle fidger. IN. First phalanx of the thumb, at its carpal extremity. MUSCLES OF THE LITTLE FINGER. ABDUCTOR MINIMI DIGITI. OR. Os pisiforme and liga- ment of the carpus. IN. The side of the first bone of the little finger. FLEXOR PARVUS MINIMI DIGITI. OR. The ulnar side of the os unciforme and ligament of the wrist. IN. First bone of the little finger. USE. It is an assisting flexor of the little finger. ADDUCTOR MINIMI DIGITI. OR. Edge of the os unci- ibrme, and ligament of the wrist. IN. The side of the metaearpal bone of the little finger. USE. To draw the little finger towards the others. LUMBRICALES. These are four muscles, lying in the palm of the hand, thin and fleshy, so as to resemble earth worms. Each of these muscles may thus be described; OR. One of the tendons of the flexor profundus digitorum. IN. The sheath on the back of the fingers, along with the interossei. USE. To move the finger on the metaearpal bone. ABDUCTOR INDICIS. OR. Os trapezium, and metaearpal bone of the thumb. IN. The first bone of the fore finger. USE. To bring the fore finger towards the thumb. INTEROSSEI INTERNI. These are muscles lying deep be* twixt the metaearpal bones, each having its origin thus : OR. By one head, from a metaearpal bone. IN. Into the sheath of the extensor muscles on the back of the first phalanx. INTEROSSEI EXTERNI. These are bicipites, and lie on the back of the hand, but betwixt the metaearpal bones. OR., The roots of the metaearpal bones. IN. The tendinous expansion of the extensor communis. The PRIOR INDICIS is a muscle of the same character with fte former, only that, lying on the radial edge of the met a- 322 i-arpal ofKthe fore finger, it cannot be so properly called an, mterosseous, as those which are seated betwixt the metacar- pal bones. USE OF THE INTKROSSII. While there seems much rea- son in the supposition, that the lumbricales, being 1 small mus- < :les, are better calculated for the quick movements of the lingers, (whence they have been called fidicinales ;) the in- terossei interni, and externi, are for the lateral movements of the fingers, or the adduction, and abduction of the fingers, nd are of the same class with the adductors and abductors uf the thumb and little finder. DISSECTION LIGAMENTS OF THE ARM. AFTER having completed the dissection of the muscles of f.he arm, we should remove them, that we may examine the ligaments ; and in doing this, we should take the opportuni- ty of again comparing their origins and insertions with the description in the Table. We should not remove every part of the tendons of the muscles which are attached to the head of the humerus ; for they are so intimately connected with fhecapsular ligament, that we shall destroy it in the attempt, The ligaments about the shoulder may be divided into three sots: 1. into those which connect the clavicle and scapula; 2. the ligaments which pass from one point of the scapula to the other; 3. the ligaments connecting the humerus and sca- pula. When the fibres of the deltoid are removed, slips of liga- ment will be seen passing from the clavicle upon the acromi- on ; these are called Ligamenta Radiata. There is also a proper capsular ligament, and occasionally an intermediate carti- lage between the acromion and clavicle; but the principal ligaments pass between the coracoid process and the clavi- cle : one will be found running from the root of the process 323 up to the tubercle on the lower part of the clavicle, andfrou< its round shape, it is called Hgctmentum conoides ; another, but of a more square form, rims from the root to the lower part of the clavicle, extending from the last ligament to near the acromial end of the clavicle; this is called ligamtnhn lt trapezoides. The ligaments which run between the points of the sca- pula, are very simple : one, of a triangular form, will be found attached to almost the whole length of the coracoid pro* from which it passes to the tip of the acromion (it is some times divided into two portions, by a little cellular membra 1 this, from its shape, is called ligammium hi angular?., or toides. By removing the fibres of the supra spinatus mu we shall discover a small ligament running from the root of the coracoid process across the notch ; this is the ligamen- tum posticum (the supra scapular nerve almost always pas- ses under the ligament, and the artery generally over it.) The ligaments which run between the points of the scapula, are called the proper ligaments ; while those which corn the clavicle and scapula, are called the common. In dissecting the muscles which pass from the scapula tu the head of the humerus, we saw the supra spinatus, tin- infra spinatus, and teres minor, all spreading their tendons upon the upper surface of the thin capsule : and on the lower part, we might have seen the ligament strengthened by th- tendon of the subscapularis. If we now dissect away all these tendons, the capsule will appear as a transparent mi brane, rising from the edge of the glenoid cavity, and pas- sing down to surround the neck of the humerus. This view must prove to us, that the strength of this joint does not consist in its capsular ligament, but in the tor. of the muscles which surround it. In examining the capsule, in a superficial manner, pears to be perforated by the tendon of the long head of tie biceps ; but when the capsule is opened, we shall find tl very thin portion of the membrane passes down into th- cipital groove, and is then reflected on the tendon of th- ce p S) S o that the tendon is actually external to tho liga- ment. When we cut open the joint, we shall see that the glenoid cavity is deepened by a ring of fibrous cartilaginous ligament surrounding its edge. We should not omit to look for large bursa y which is between the deltoid and the capsulai ligament. The ligaments of the elbow joint are a little complicated, in consequence of the head of the radius entering into the articulation ; but still, as the joint is nearly a simple hr 324 the principal ligaments will be lateral. We shall find here* as in all other joints, a capsular ligament ; but its appear- ance is not that of a thin membrane, except at the posterior part, in consequence of its being covered both on the fore and lateral parts, by slips of ligament from the tendons of the muscles : those on the fore part are called accessoria a?i- tica ; while those on the sides are described as distinct fate* -ral ligaments. The external lateral runs from the external condyle to tht internal, and may be divided into two parts, we shall easily distinguish ; for one portion restrains the joint, when it is bent to a certain extent ; and the other checks it, when it is too much extended. The radius is articulated with the external condyle ; but by rolling it, we shall see that it is also connected with the ulna, by a thickening of the general capsular ligament, which is called ligamentum coronaritim. In taking off the muscles, to show the interosseous ligament, we must take care that we do not cut the ligamentum obliquum, or transversale^ which runs from the ulna to a point of the radius, below the tubercle. The wrist is rather a complicated joint ; but as the move- ments between the bones of the carpus and bones of the fore arm, are principally flexion and extension, we shall have on the inside and outside, lateral ligaments ; these ligament? are very loose and much connected with the general capsule . which will be found to be very strong, in consequence of the many slips which cross it. The capsular ligament does not bind the bones very closely together, but allows of a very considerable degree of lateral motion. When we open the capsular ligament, we shall find that the end of the ulna does not correspond exactly to the cune fbrm and lunar bones, but that there is a portion of cartilage tnterposed between them. We may now separate the car* pus from the radius and ulna, and then examine the connex- ion which is between these two bones. The convexity of the head of the ulna will be found attached to the concavity on the radius, by a coronary ligament, which, however, IF Called ligamentum sacciforme, or membrana sacciformis. The carpal, and the heads of the metacarpal bones, are connected together by capsular ligaments and by accessory slips, which are easily dissected : it would be needless to give them separate names. The metacarpal bones, and the seve? ral phalanges of the ringers, are united by capsular and lateral ligaments, which, though very simple, ought to be carefully studied, as the dislocations of the finger, and particularly of the thumb; are sometimes very troublesome. 325 DISSECTION OP THE ARTERIES O'F THE SHOULDER AND ARM. IN the first dissection of these arteries, they should be in- jected ; and that all the vessels of the shoulder may be seen, 'the injection should be made in the same manner as that de- scribed at p. 241. It may be done from the subclavian arte- ry, or from the axillary, after the arm is removed from the "body : but in either of these methods, a great many vessels mus't necessarily be destroyed. The manner of dissecting the arteries which arise from the subclavian, has already been described at page 243 ; st> we may now pass to the description of the branches which arise from the artery, after it has passed under the clavicle ; -and first, of that division of the artery which is called the Ax- illary. The pectoralis major, the deltoid, and the latissimus dorsJ, should be dissected in the manner recommended in the dis- section of the muscles, at page 199 ; but in doing this, we must take care to avoid the small branches which will be found on removing the cellular membrane. If we are dis- secting a female subject, in which the breasts are enlarged, *>r where milk has lately been secreted, we shall find upor. the surface of the pectoralis major a great many arteries pass- ing to the mamma. "Between the deltoid and pectoralis, we shall see arteries running down, and a vein passing up; the arteries af branches of the T/wracica Humeraria ; the vein is the Ce- yhatic. On the lower edge of the pectoralis, and upper edgj? of the latissimus dorei, branches of the Thoracica Alaris and of the Subscapular, will be found. By dissecting between the two muscles, we shall expose the axilla, in which .we hall see a net-work of vessels and nerves, complicated with many lymphatic glands. In considering the surgical anato- *iy, all the parts of the axilla will -excite much interest ; but. Bd 326 at present we should trace the branches of the arteries only through it. That we may follow the arteries more easily, we should now raise part of the pectoralis major from its origins. In doing this, we shall be obliged to cut through many branches : some of these come, through the intercostal muscles, from the mammaria interna ; but the principal ones are branches of the Thoracica Longior, or Mammaria Externa^ which, when the muscle is farther raised, will be seen rising in com- mon with the Thoracica Humeraria, or Acromialis ; the branches of which have already been observed passing be- tween the deltoid and pectoralis major. The muscle may now be completely thrown back, and then the pectoralis minor will be exposed. A small artery will now be seen passing into the space between the first and second ribs ; this is called the Thoracica Prima, or Supe- rior. On the lower edge of the pectoralis minor, some branches will be seen running into the fat and glands of the axilla, which must be carefully followed, by dissecting them with the forceps andscissars. These branches are describ- ed as coming from one trunk, which is called the Thoracica Jllaris ; but they generally arise in two or three small branch- es. The trunk of the artery may now be fully exposed. It will be found covered by the veins, but lying below the level of the axillary nerves. Until it has fairly passed under the pectoralis minor, there will be no difficulty in separating it. from the plexus of nerves ; but immediately after it passes this muscle, it will be found to be completely enveloped in the plexus. The arm must then be bent ; which will relax the plexus, and enable us to dissect the cellular membrane from between the artery and nerves. When the artery comes opposite to the upper part .of the insertion of the latissimus dorsi, it gives off the Subscapulw artery, which will be found to pass under the scapula, and to give off numerous branches to the serratus magnus, subscap- ularis, latissimus dorsi, &c. ; and frequently to the axillary glands. We should now observe the beginning of a branch, which we cannot follow to its termination until the body j* turned or the arm separated. This will afterwards be found to run to the dorsum of the scapula ; whence it is called the Dorsalis Scapulae. As the main trunk is so covered by the plexus, at the point where it gives off the subscapularis, we shall probably not at once discover the Posterior Circumflex ; which rises close to the trunk of the subscapularis, and sometimes in union with it. After we have found this artery, we shall not be able to 327 follow it far in the present position of the limb, as it passes between the long head of the biceps and humerus, to be dis- tributed on the deltoid. Its branches will be seen on dis- secting the back part of the arm. We generally find another artery, which passes to the an- terior part of the joint, rising immediately opposite to the the last ; it is called the Anterior Circumflex. The plexus of nerves must be pulled down to expose it. Jt is a small ves- sel, and generally runs between the tendons of the pectoralis major and the capsular ligament. We shall now have traced the main trunk fairly past the insertion of the pectoralis major and .latissimus dbrsi ; and here its name is changed to Humeral or Brachial, which it, retains until it reaches the elbow. The dissection of the portion between the scapula and el- bow is very easy. If we do not wish to keep the arm and chest connected, we may now, without hurting any vessels, separate the arm from the body. Before following the trunk of the artery, we should turn the arm round, and make a superficial dissection of the mus- cles lying on the scapula.* In dissecting the deltoid, seve- ral of the branches of the thoracica humeraria, and of thecir- cumflexa posterior, will be found. There will also, perhaps, be several branches of the supra scapularis (which is some- times a prolongation of the Transversatis Colli, described at page 243,) passing into the substance of the supra spkiatus muscle. f On the muscles below the spine, many branch- es of the dorsal-is scapulce^ and of. the subscapularis, will be found. All those arteries which pass to the scapula, are distributed so much on the surface of the bone, that, before we can show them, it will be necessary to remove the mus- cular fibres. The superficial dissection which has been begun on the deltoid, may be continued down upon the triceps. As we approach the elbow, we must carefully avoid the superficial branches, for they form inosculations with those of the fore arm. Those on the external part, are branches from the cir- cumflexa posterior, and the profunda superior ; while those on the inside, are from the profunda inferior, and the anas- tomotica. * This may be done without separating the arm from the body, by throwing the arm over the chest. f W r hen there is this arrangement of the artery, it very seldom passes under the ligamentum posticum. It appears to pass under the ligament, only when it arises from the sub- clavian, as a distinct branch, and low down. 328 We may now turn the arm, and continue the dissection of the trunk. An incision is to be made, down to the elbow, in the course of the artery : when the skin is dissected off; a thin facia will be seen to pass from the inside of tkc triceps to the biceps ; when this is opened, the trunk will be seen on the inside of the biceps, not now enveloped in a plexus of nerves, but with the radial, or median nerve, lying close up- on the inner side of it. The first branch (which has a name) we shall find, by' looking- for the muscular spiral nerve, or between the heads of the triceps. The artery is called the Profunda Superior; we may trace it into the deep parts of the arm, by following it along with the nerve. We may now for a moment disregard the branches, and trace the trunk to the elbow r , taking care not to cut any ves- sels. On the side of the artery next to the biceps, w r e shall see a great number of branches going off; these, however-, are merely muscular branches, and there are no particular names for them. The only one of these, which we should particularly observe, is a trunk, passing off at the lower part ofthecoraco brachialis to the bone: it is called Nutriti<* Magrut Humeri. On the side of the artery nearest to the jbrachialis internus, we shall find three, four, or five branches, all taking nearly the same course towards the inside of the elbow, and to communicate with the recurrent arteries of the fore arm. The upper one is generally called the Pro- funda Interior ; while the largest of those below, is the An- astomoticus Magnus, and .the next in size, the Anastomoii- cus Minor. We shall now have traced the main trunk to the bend of the arm, where it generally divides into the Radial and Ub- nar.* The trunk will be found lying close by the edge of the bi- ceps, and passing under the portion of its tendon which is in- serted into the fascia of the fore arm. .Before following the trunk, we should make a dissection of the fascia of the fore arm ; this may quickly be done, by making a cut through the skin, from the elbow to the wrist, and by then dissecting tbe skin off from all around the arm. We need not preserve the small branches which perforate the fascia to supply the skin ; but we must take care of branches which run around *The bifurcation occasionally takes place higher upon the arm ; but in what proportion of instances, Ihave a difficulty of determining; during some seasons I have observed it, in -nearly every third body. I think, however, it may be saici" to occur in a proportion, of about one to ten, 329 the elbow, and of any small branches which may be found near the wrist ; for the arteries there, are very irregular. In following the trunk, and the commencement of the ra- dial and ulnar arteries, we must be very careful ; as there- is always a quantity of fat and cellular membrane interposed between the tendons of the biceps, and the insertion of the brachialis internus, in which space, the artery generally divides : to see it distinctly, we must cut through the tendin- ous membrane which passes from the biceps to the fascia, of the fore arm. As the Radial lies more superficial than the ulnar, we should first trace it to the wrist. This will be very easy ; for by merely cutting through the fascia, we may follow the artery over the tendon of the pronator teres, towards the ra- dius, and then it runs down parallel with the bone, lying on the flexor pollicis longus, and between the supinator longus and the flexor carpi radialis. We need not here enumerate the several branches which are going to the muscle ; for they are very irregular; but we should particularly mark the branch which turns back, and round the tendon of tho biceps, to pass on the elbow : this is the Recurrens Radialis. The only other branch of importance, is that which is given off at the point where we generally feel the pulse ; viz. the Superjidalis Voice. : but this branch is very irregular in its size. We should not now trace the radial farther, but return to the ulnar. The ulnar passes much deeper than the radial ; conse- quently, it is more difficult to trace its branches. It will be found running at once deep into the arm, to pass under the pronator teres. While the artery is under this muscle, we shall often find a branch pass off, which is nearly as large as the ulnar itself; viz. the Interossea Interna. But before this great trunk is given off, we shall generally find a branch, running back to the elbow ; viz. the Recurrens Ulnaris. After these two branches are seen, the trunk may be traced down to the wrist, between the superficial and deep layer of the muscles : in its course, it gives off' many branches, the most important of which, will be enumerated in the Table. We should now trace the branches of the interoseea, for it is the vessel which supplies the principal parts of the fore arm. The trunk has already been seen, coming offftom the ulnaf, under the pronator teres, from which, we may now trace it, along the interosseous ligament, and between the flexor digitorum profun$us and flexor pollicis. But we shall generally find, that almost immediately on its rising from the ulnar ? it gives off a large branch, which may be traced? 330 through the ligament, to the supinators and extensors, and is lost at last, on the back of the hand. But before thin (the Interossea Externa) arises from it, there is generally a recwvent sent off, to inosculate with the anastornatici upon the elbow. When we have followed the internal artery as far down as to the pronator quadratus, we shall find it divide into two vessels ; one of which may be traced^ through the interosse- ous ligament, to the back of the wrist, while a smaller branch is continued down to the fore part of the bones of the carpus. The arteries of the hand are very numerous, and very com- plicated and difficult to dissect ; but still the small branches will easily be understood after a general arrangement is made. We should commence the dissection, by raising the skin from the palm of the hand, so as to expose the palmar aponeurosis. On removing the skin, a number of small branches will be seen ; those on the middle and outer part, come from the ulnar ; while those which are on the inside, and on the muscles of the thumb, are from the radial: but here, we shall probably find one larger than the others, viz. the Superfidalis Voice, When the skin is dissected from the back of the hand, the main trunk of the radial will be found passing between the tendons of the extensors of the thumb ; from which, it passes deep between the abductor indicis and adductor pollicis, to form the deep arch. There are no directions required, for tracing either the ulnar or the radial artery; farther than that of following them patiently from trunk to branch, with the forceps and scissars. In the first dissection, every thing is to be cut away, except the arteries and the tendons. We should first expose the Superficial Jlrch, which is formed by the ulnar ; and then the Deep Arch, formed by the radial : but this, we shall find to be very difficult. The arteries which are seen on the back of the wrist, and on the thumb, are generally from the external interosseal, and the radial, TABLE OF THE ARTERIES OF THE SHOULDER AND ARM. It is agreed by all authors (who have taken the description of the arteries from the dissection of many bodies,) that there are no vessels more irregular, than those which rise from the. subclavian. Bu4-the general arrangement is very simple . for we have here, as in the study of the arteries of the leg.. 331 r>nly to rec6llect, that the names of the branches correspond to the parts which the trunk passes. The following sketch will be found to agree, in most re- spects, with the description of Haller ; and I have attempt- ed to make the arrangement correspond with what I think is most commonly seen : The great trunk, in its course from the aorta to the fin- . gers, receives names corresponding to the parts which it pas- ses. From its branching off from the aorta, until it passes under the clavicle, it is called Subclavian. From the upper edge of the pectoralis minor, until it passes the insertion of the latissimus dorsi and pectoralis major, Axillary. From this point, until the division at the bend of the arm, Hume- ral, or Br actual. From the bend of the arm to the wrist, Radial, Ulnar, and Interosseal. From the wrist to the fin- gers, -Superficial Arch, Deep Arch, and Posterior Arteries. The names which are given to the branches, refer to each division of the trunk. The branches of the subclavian have already been enu- merated at page 251. The next division of the artery is the Axillary : from it, we have, thoracica superior ; thoracica longior, or mam- maria externa ; thoracica humeraria, or acromialis ; thora- tica alaris ; mbscapularis ; circumf.exa posterior* ; circum- flex a anterior. Thoracica Superior, gives branches between the first and socond ribs. Thoracia Longior^ to the pectoralis major and mamma. Thoracica Humeraria, branches between the pectoralis major and deltoid. Thoracica Alaris, to the fat, glands, pectoralis minor, &e. Subscapularis, 1. to the axilla and glands ; 2. to the. sub- .ioapular muscle; 3. infra scapular branch to the muscles of the back ; 4. dorsalis, or circumflexa subscapularis, to the muscles on the back of the scapula. Circumflexa Posterior, branches to the heads of the tri- i'eps, coraco brachialis, deltoid, and capsule. Circumflexa Anterior,- to fche periosteum and capsule. The third division of the artery is the Humeral or Brachi- &1 ; gives, 1 . a set of small branches to the muscles ; 2. profunda humeri superior ; 3. profunda humeri inferior ; 4. ttnastomotica magna. From the Set of small Branches, twigs go off to the biceps and brachialis interims, and also the arteria nutritia humeri. Profunda Superior, 1. to the muscles; 2. radialis commu- nicans, to the external condyle ; 3. branches to the back of the eibow ; to unite with the recurrens interosjsea and radi- 332 Profunda Inferior, to the brachialis interims and biceps , 2. to the external condyle and supinator ; 3. to the ulriar nerve and back of the elbow joint. Anastomotica Magna., 1. branch communicating with the profunda ; 2. descending superficial branch ; 3. descending deep branch : these two form, with the recurrents of the ar"- teries of the fore arm, the arcus anterior ; 4. transverse branch which goes behind, forming, with the profunda and recurrents, the circus posterior. The fourth division of the great artery is into the Radial ;ind Ulnar. The Radial gives off; 1 . to the supinator ; 2. recurrens radialis ; 3. in succession to the supinator., pronator and flexor muscles ; 4. superficialis voice ; 5. irregular branches to the wrist ; 6. dorsalis pollicis ; 7. dorsalis carpi ; 8. dorsalis me- tacarpi; 9. magna pollicis: 10. radialis indicis ; 11. deep palmar arch y which inosculates with the superficial arch from the ulnar, and gives off the interossea to the metacarpal spa- cos. Ulnaris, gives off the inferosseal artery : but before it does so, it sends off some smaller ones. 1. to the pronator ; 2. Perforans, through the interosseous ligament to the back of the joint ; 3. recurrens ulnaris, which has a superficial and deep branch ; 4. arteria nuiritia ; 5. interossea commu- nis (this will afterwards be considered as a principal branch,) t>. irregular branches to the muscles ; 7. dorsalis manus ; 8. to I he muscles of the little Jing-er ; 9. palmaris profunda^ which, uniting with the racial, forms the deep arch ; 10. superficial palmar arch, giving ^ff yolans ulnaris minimi digiti, digita- lis volans prima, digitalis volans secunda, digitalis volans tertia; these are the vessels to the fingers ; ll. communi- f'tfn*, joining the radial, on the thumb. Interossea Communis : 1. to the muscles and ligaments of the joint; 2. perforans superior, which gives off ramus de- scendens, and recurrens interossea ; 3. irregular branches to the flexor muscles : 4. perforans inferior ; passes through the upper edge of the pronator quadratus, and gives branches to the back of the wrist; 5. interossea volans anterior, or anterior articular artery of the wrist. 333 DISSECTION OF THE OF THE ARM: IT is almost needless to inject the veins of the arm, unless it be for the purpose of making a preparation ; for a much better knowledge is gained of the course of the superficial veins, by putting a ligature round the arm of a thin* muscular man, than is ever done by injecting, or dissecting them. As the deep veins all accompany the arteries, their course may also be easily understood ; but in making the surgical dis- section at the bend of the arm, it will be useful to have some of the veins filled. Though I do not think it neces^ry for the dissection, I shall here describe the manner of injecting the veins, that they may be preserved : In consequence of the numerous valves which are in the veins, it will be impossible to inject them from the subclavi- an; the injection must be thrown in, from one of the vessels on the hand. Those on the palm are so small, that it will be needless to try to introduce a pipe into them. We must look for a vein on the back of the hand. That vein which runs up from the fore finger, or the one between the little and ring finger, will generally be found to be the best. After we have introduced the pipe, a piece of the skin over the vein, should be included in the ligature ; or we shall be in danger of tearing the coats of the vein, while we are injecting it. The blood is to be first thoroughly pushed out of the veins, by injecting warm water into them, and allowing it to escape by the subclavian. This injection of warm water, should be repeated several times ; and previous to the injection with the wax, the water should be forced, out, by holding the arm., with the hand, perpendicular to the foody, and rubbing the vessels, down towards the axilla. A ligature may be put round the subclavian vein : but it should not be tied until the injection is thrown in from below ; so that any water which may not have been forced out, may be pushed before the in- jection; as soon as the wax appears &t the-sbclavian, an as- sistant should tie the ligature. The injection made from single vein, will very seldom be successful, we may, there - 334 fore, be obliged to put the pipe into one or two different veins \ but if, in cleansing the veins of the blood, the valves be much broken, the injection may pass easily from one vein to the other. The dissection of the veins is very simple ; for all the cu- taneous veins, when distended with wax, will be visible ; and to expose them, it will be only necessary to remove the skin. As the deep veins follow the course of the several arteries, they require no further description.- If the injection has been successful, it will have filled the veins of the hand below the part into which the pipe, was put; a plexus will be found running between the knuckles, and forming an arch on the back of the hand ; this has been called the Plexus, Dorsalis Manus, and the arch, the Arcus Venoms Dorsalis. From the part of the arch nearest to the thumb, and from a vein on the thumb, there is a trunk rises, which is called Vena Ce- phalica Pollicis ; this name heving been given to it by the Arabian anatomists, from the idea that opening it was useful in diseases of the head ; this vessel, when joined by pthi(r veins of the arch, forms a trunk, that runs up the radial edge of the arm, and is called Vena Cephalica Minor, or Radialis Exierna : at the bend of the arm, this is joined by the ^Median Cephalic ; and by this union, the Great Ceph- alic is formed, which passes up, first between the tendons of the biceps and triceps, and then between the tendons of the pectoralis major and deltoid, to dip into the axillary vein. The large vein, which is on the ulnar side of the arm, is cal- led Basilica, from a strange fancy of the ancients, that bleed- ing from this, was a sovereign remedy for many diseases ; and they moreover conceived, that the vein of the right arm belonged to the liver, and that of the left, to the spleen. This vein is formed by the vessels of the arch nearest the little finger, and by the vein that is between the little and ring finger ; which has, from the same conceit, been called Salvatella. From this source, we may trace the basalic ; sometimes in one or two branches, or as a plexus, to the ul- nar side of the arm, and here it is sometimes called Ulnaris Supcrficialis, or Culritalis Interna. It passes up by the inside of the tendon of the biceps ; there it receives the median ba- silic. It then passes deep by the side of the artery. It is sometimes found joined to the venae comites ; or it passes singly to the outside of the tendon of the pectoralis, and then falls into the axillary vein. On the fore part of the wrist, we see a plexus coming from the thumb and palm. This plexus is frequently con- tinued for a considerable way up the arm, before it forms 335 a trunk ; which gives out branches both to the basilic and cephalic ; the trunk is called Median, or Vena Superficialis Communis. Near the bend of the arm, it generally divides ; one branch goes to the basilic, and ivS called Median Basi- lic,, and the "other to the cephalic, and is called Median Cc- phalic*. It is needless to describe the deep veins of the arm, as they accompany the arteries, whence they receive the names Comites, or Satellites : there are generally two, accompany- ing each of the principal arteries. We have now traced the veins up into the axilla ; here the trunk is called Axillari*: and at this part, we may trace , branches into it from the shoulder, from the scapula (the Ex- ternal and Internal Scapular,} and some from the side (the Thoracic Veins.] We may then trace the vein under the davicle ; and there it is called Subclavian. If we have in- jected the great veins, we shall see the union, on the left side, with the Internal Jugular ; at this angle, the thoracic duct enters. The great trunk may be traced across the chest, to unite with those of the opposite side, to form the vena cava descendens ; but the manner of showing these is described more fully at page 242. DISSECTION NERVES OF THE ARM. THE dissection of the nerves of the arm may be made on the same limb in which the arteries are traced. The nerves which form the Axillary Plexus, viz. the Four Lower Cervical, and .First Dorsal, ' will be found coming from the spine, between the scalenus anticus and scalenus medius. These may be dissected with the branches of the subclavian artery. It is from this plexus that all the nerves pass to the arm. But in dissecting the external part of the axilla, we shall discover certain small nerves passing towards* the pectoralis major and latissimus dorsi, these are called the Thoracic Nerves : they are rather irregular in their course, as they occasionally come from the intercostal nerve?- By dissecting deeper, we shall expose the great plexus, .T?y 336 Examining the upper part of the plexus, we shall see a nerve passing towards the root of the coracoid process, viz. the Supra Scapular Nerve ; which may be traced through the notch to the supra spinatus muscle. Another nerve, the In- fras Capularis, will be found passing from the posterior part of the plexus : it lies upon the subscapularis, and sends its branches between this muscle and the latissimus dorsi ; but. its branches must not be confounded with those of the exter- nal respiratory r , which cross under the plexus, to the serra- tus and intercostal muscles. If we now pull out the plexus, and look to the back of it, and immediately above the insertion of the latissimus dorsi. we shall find the nerve, which, from its encircling the joint?, is called the Articular ; it rises very frequently in common with the infra scapular. The other nerves which pass out ftom the axillary plexus, will easily be recollected ; for there are only three which go to the integuments, and three which supply the muscles and tips of the ringers. The cutaneous nerves must necessarily be traced before the deep ones. An incision may be made through the skin only, in the line of the biceps muscle, down to the middle of the fore arm. In dissecting the flap, towards the chest, small nerves will be found coming through the interstices of the ribs ; some of which may perhaps be traced near to the el- "bow ; but these intercostal branches generally terminate on the skin, a little below the axilla : and for the supply of the skin, immediately below this point, we shall find a nerve that rises from the most superficial part of the inner side of the plexus. As this nerve was particularly described by Wrisberg, it is called th Cutaneous of Wrisberg. There is, however, some difficulty in determining whether this should be considered as a distinct nerve, or as only a branch of the Internal Cutaneous ; which will now be seen rising from the ulnar side of the plexus. The branches of this last nerve will afterwards be found to be continued to the skin on the inside of the fore arm. We may now dissect off the other flap of the skin. We shall find no branches upon it until we come opposite to the Lead of the brachiaiis internus ; and there we shall discover some considerable branches passing into the skin. If we trace these back towards their origin, we shall find that they have come from between the brachiaiis and biceps, having perforated the coraco brachiaiis ; and that they arise front the radial, or upper side of the plexus. The principal branch having been described by Casserius as the nerve which per- forated the coraco brachiaiis muscle, has been called .thf; 33t jPerforans CasserU ; but, from its giving branches to the co- '?aco brachialis and biceps, as well as to the skin, it is some- limes called the Muscuh Cutaneous :. however, from its rela- tive situation on the skin, it has got, more commonly, the name of External Cutaneous. The branches of the external and internal cutaneous should now be traced to their terminations. The external, as soori as it passes from below the biceps muscle, divides into three branches upon the skin ; two of which are distributed over the supinators, while the other passes down to the wrist . The branches of the internal cutaneous may be traced in Connexion with the basilic vein ; along the course of which they pass, in three or four branches, towards the wrist. The connexion of the branches of both these nerves with the Veins at the bend of the arm, will be fully described in the Surgical Dissection of that part. The three great nerves, the Radial or Median, the Ulnar and the Muscular Spiral, may easily be traced at the same time with the branches of the arteries. The Median or Ra- dial, will be found to rise from that division of the plexus which surrounds the artery, and to be often connected with the perfbrans Casserii. It may be traced along the inside of the artery, and closely connected with it. When at the bend of the arm, it gives off three branches, which supply the muscles of the fore arm. But the principal nerve does not now run in the course of either of the great arteries, but will be found to pass in the middle of the fore arm, between the flexor sublimis and flexor profundus ; whence it is more, properly called Median than Radial. It then passes under the annular ligament ; but previous to this, it generally givers off some small branches to the integuments upon the inside of the thumb. In the palm of the hand, it will generally be ^found to divide into five branches, one of which may be traced to the abductor and flexor pollicis brevis ; another to the adductor and side of the thumb ; a third, to the fore fin- ger ; the fourth passes to one side of the fore and middle fin- gers ; and the fifth to the other side of the middle, and to one side of the ring finger : besides these branches, lesser ones will be found* passing into the email muscles in the palm &f the hand. The Ulnar rises from the lower and inner part of the plex- us. The internal cutaneous will often be found to be the first branch which it gives off. It may then be traced down be- hind the inner condyle of the humerus ; but before it reaches this point, some branches will be seen going from it to the skin and triceps muscle* Immediately after passing the Condyle, it gives a 1 branch to the flexor muscles ;- it theft Ee 338 passes between the flexor carpi ulnaris and flexor digitorum sublimis : here it will be found to join the ulnar artery, along which it may be traced to the wrist. In this course it gives off a few muscular branches; but when near the wrist, a branch will be found which passes under the flexor carpi ul- naris, and over the lower end of the ulna, to be distributed on the back of the hand, and on the little and ring fingers : this is the Ramus Posticus. The trunk of the nerve passes under the annular ligament, into the palm, and there it will be found to divide into two principal branches, which are sometimes called the Sublimis and Profundus. The sublimis may be traced to the intern- ments on the ulnar side of the hand, and to the small muscles of the little finger ; then, to the sides of the little finger, anil one side of the ring finger. The profundus forms a sort of deep palmar arm, to supply the muscles. The Muscular Spiral nerve will be found lying quite be- hind the artery, and rising from the lower and back part of the plexus. It will be seen to give off many branches, al- most at its origin, to the muscles contiguous to it. The trunk may be traced along with the profunda superior arte- ry ; but we may generally observe a large branch rising from it,, before it perforates the triceps ; this branch accompanies the nerve and the artery for a short distance ; it will then be found to pass directly through the triceps, and to emerge up- on the skin, by the side of the supinator longus, from whence it passes, to be distributed nearly in the same manner as the branches of the external cutaneous. The principal nerve may be tra-ced between the brachialis internus and supinator longus ; it there gives off* a branch to the elbow, and it then divides into the profundus and superfi- dnHs. The profundus may be traced through the supinator brevis ; it will then be found to twist round the radius, and to divide into branches, for the supply of the muscles on the back part of the arm. But the other division, the superficial, is by far the most important : it lies between the supinator longus and pronator teres, from whence it may be traced between the supinator and flexor carpi radialis, and so close upon the radial artery, that it might be called a radial nerve : when near the wrist, it passes under the tendon of the supi- nator longus, and there it lies directly over the radial artery, viz. between the extensor muscles of the thumb. The nerve is, finally distributed on the back of the hand, on the back of the thumb, fore, middle and ring fingers. In recapitulation of the nerves which arise from the axilla- ry plexus, they may be arranged thus : Three to the shoul- der,, viz, Supra Scapular^ Infra Scapufar, and Articular. -~ 339 Three to the skin : External Cutaneous, Internal Cutaneous, and Cutaneous of Wrisberg. Three to the muscles : Radial or Median, Ulnar, and Muscular Spiral, SURGICAL DISSECTION, THE ARM. THK most important part of this dissection, is, that of the vessels about the elbow and wrist, for they are liable to be opened by .accidents which may appear trifling, but, if neglect- ed, or if treated by a surgeon who is not fully master of the anatomy, may he followed by the most serious consequences ; sometimes by the loss of the limb, or even by death. The dissection of the subclavian artery, above the clavicle, should also be most carefully made ; for though it is very im- probable that an operation on the artery itself will be follow- ed by success, still we ought to know accurately the connex- ions which it has with the parts in its vicinity, that we may be enabled to avoid -it in extirpating tumours, or even to take it up for a case of aneurism. The question of the rule of practice, in aneurism of the subclavian, is very difficult to determine. We shall find, by the history of the cases of aneurism of this artery, that the relative position of the parts connected wjth it, are so changed by the aneurismal tumour, that even though we may have a very accurate knowledge of them in their natural state, still we may be foiled in the at- tempt to take up the artery when an aneurism has formed. When it is known, that even Sir Astley Cooper has been obliged to stop in the middle of such an operation, we may be satisfied that it is not a very practicable one : his words are," The clavicle was thrust upwards by the tumour, so as to make it impossible to pass a ligature under the artery, without incurring a risk of including some of the nerves of the axillary plexus : the attempt was therefore abandoned.'' The game histories will also lead us to doubt the proprie- ty otVcc/' attempting this operation ; for, in the greater nun> 34O ber of cases, where even the artery has been neatly tiecf; the vessel has ulcerated above the ligature, and this, most probably, in consequence of the very short distance that there is between the large trunks, as the passage of the blood through them, will necessarily prevent the formation of a clot behind the ligature, which appears to be the prin- cipal source of the great success attending operations on the external iliac and carotid arteries. I cannot enter into the discussion of what should be done, in aneurism of the subcla- vian ; but I shall merely hint to the student, to inquire into the propriety of the proposal to remove the arm. To com- prehend the rationale of this proposal, he must take into con- sideration the effect which amputation of a limb, lias upon the great artery. The anatomy of the artery below the clavicle, should be- more interesting to the student ; for the tying of it, is a more practicable operation, and has occasionally been attended with success. 1 shall here introduce the description, which my friend, Mr. Smith, of the Leeds hospital, has given of the operation, which he performed on a young girl who had secondary haemorrhage from the stump, after the arm had been torn off by machinery : " One assistant compres- sed the artery, above the clavicle ; another, with the hand upon the acromion process, depressed the shoulder ; and a third pressed a dossil of lint in the stump, to restrain the he- morrhage. I then made an incision, from three to four in- ches in length, beginning about half an inch from the ster- nal extremity of the clavicle, and half an inch below it, fol- lowing the course of that bone towards the shoulder. By the first incision, I divided the integuments ; and by the second, the clavicular portion of tl/e pectoralis major: when this retracted, the edge of the pectoralis minor was seen. Several small arteries and veins were now visible, crossing the course of the artery : these were tied, above and below, before they were divided, as the blood issuing from them, would have retarded the operation. The great vein was then seen, and with an appearance of pulsation, caused by the artery below it. The artery was carefully separated from it, for about the third of an" inch, by the handle of a scalpel ; the vein was drawn to one side, by a curved probe ; a directory was then placed under the artery, to raise it a little, and a silk ligature was passed along the groove of the directory, by means of an eyed probe : the ligature was di- vided, and the probe withdrawn ; to the upper ligature was then tied as high as possible, and the other as low, but there was, still, just as much space left, between the liga- tures, as to allow of the artery being divided with safety/' 341 On my questioning the utility of dividing the artery between the ligatures, my friend agreed to my objections ; saying, that he had clone it, in compliance with the opinion of his senior, as he did not conceive any harm could result from it. The patient lived sufficiently long, to show, that the cali- bre of the artery was properly obliterated by the ligature: she died in consequence of haemorrhage from the face of the stump, which, on dissection, was discovered to have come from the subclavian, above the ligature, through the supra scapular branch of the inferior thyroid. This is highly im- portant to recollect ; because it is a proof that in a case of axillary aneurism, even though the subclavian has been tied, still the aneurismal tumour may be supplied with blood from the anastomosing branches, and may at last burst, even though the main trunk may be obliterated above the aneu- rism. We should now examine the parts in the axilla. These parts are so exceedingly complicated, that no surgeon should venture to operate upon them, unless he has such a know- ledge, as will give him boldness and decision. In making the dissection, we should endeavour to keep the .parts as much in their natural situation as possible. After laying bare the tendons of the pectoralis major, and of thelatissimus dorsi, we have to observe the place of the axillary glands, the size of the branches of the thoracic arteries, and of the scapular, and also the nerves which come from the intercostal spaces, to pass amongst them. The whole plexus of nerves, and the axillary artery, will be found to be braced down by a web of aponeuroeis. When this is lifted, w r e shall find that the nerves closely surround the artery ; which shows, that the artery, when wounded, must not be secured by diving with a needle : by such an operation, the nerves would be included, and the ligature would not come away until it was cut from the bundle of nerves. When the nerves and artery are disentangled, and the divisions of the -plexus are traced, we may recognize the radial nerve running upon the fore part of the humeral arte- ry ; the ulnar nerve taking its course towards the inner con- dyle of the humerus ; the muscular spiral nerve passing through the triceps, and behind the bone ; the external cuta- neous nerve passing before the humerus, and through the co- raco brachialis. We should then turn our attention to the circumstance of wounds penetrating the axilla ; for, often, when a ball has passed through the arm-pit, or when it lodg- es, the track, or seat of it, may be discovered by the numb- ness in the part of the arm supplied by the extremities of the nerve. Thus, if there should happen to be a wound of the E e2 342 axilla, attended with great haemorrhage, and yet it is nor evident whether the axillary artery or the subscapular arte- ry be wounded,, if we find the muscles supplied by the radial nerve, to be paralytic, and the sensibility of the thumb and fore and middle fingers, lost, the ball, most probably, will have passed through the main artery, since the radial nerve clings around it. We may also consider how the head of &e humerus being dislocated, may press on the plexus of nerves, or the artery, and cause one symptom announcing dislocation. The question may pass through our minds. Does a punctured wound of the axillary artery call for ampu- tation ?^ Does a wound, where the artery and the whole plexus of nerves are cut through, require amputation? We should likewise consider the parts in the axilla, and the mus- oles of the shoulder, in relation to the amputation of the arm At the shoulder- joint. We ought to observe the great group of lymphatic, or absorbent glands of the axilla, for these, when diseased, and clustering together, form a tumour, which it is dangerous to extirpate. The most important tumour, is that which is caused by die irritation proceeding from the cancerous breast. But we should recollect, that, if morbid matter be absorbed in the hand, buboes may be formed here, as in the lymphatic if lands of the groin. These cases are so common, that we may occasionally have opportunities, in the dissecting-room, of examining them. We shall find that, when the glands are not far advanced in disease, only feeling hard and en- Jarged, if a small incision be made over them, there is dan- ger of their escaping, by slipping amongst the loose cellular 1 substance. They should be firmly fixed with the two fin- gers, so that when the incision is made, they may start out ; or the fingers, should not be removed from them, when small and moveable, until they are taken up by the assistant's hook, If the glands have become much enlarged, they will form, adhesions with the surrounding cellular membrane; and they will group together, forming a fixed indurated mass, (n such cases, we often find numbness of the arm, and cede- matous swelling. The numbness, v*e may understand to bt a consequence of the pressure on the nerves : the swelling is : produced by the disturbance of the absorbents. The dissection may now be prosecuted by taking the in- teguments off the inside of the arm. After recognizing the- muscles in this more partial view, we ehould trace^ the branches of the humeral artery : we shall find the radial in company with the main artery ; the ulnar nerve ac< y the pjofunda interior ; and the piot'unda sure 343 nor, and mustular spiral nerve, passing together between the heads of the triceps. We should now observe the manner in which the hume- ral artery, and radial nerve, and vence comites, are involved in a sheath, and bound down by a membrane ; and particu- larly, how they pass under the stronger fascia near the bend of the arm. We may see, that, to cut for the humeral arte- ry, we have only to lay bare the edge of the biceps flexor cubiti, to open the sheath, and avoid the radial neive ; - that, high in the arm, the nerve is superficial to the artery ;, that, towards the bend of , the arm, it is on the inside of the artery. The Full Anatomy of the Bend of the Arm is very impor- tant. The following are the chief circumstances to be no- ticed* : On the fore part of the arm, we should save the superfi- cial veins ; viz, the cephalic vein, which is coming upon the radial edge ; the basilic, on the ulnar edge ; the median, in the centre. We should particularly attend to the divisions of the median vein, which are commonly selected for bleed- ing ; and to the manner in which they are connected with the two superficial, or cutaneous nerves. Betwixt the su- pinator longus, and the outer edge of the biceps muscle, we; shall find the external cutaneous nerve : we may trace its branches under the cephalic, and median cephalic veins- The internal cutaneous nerve will be found coming directly down from- the inside of the arm, over the fascia : the prin- cipal branch goes under the vein ; but sometimes a small fila- ment passes over it. We may now lift the fascia covering- the humeral artery, and observe how thin, but, at the same time, how strong it is. If, in bleeding in the median basilic, the lancet transfixes rhe vein and the fascia, the artery may be opened. The consequence of such an accident will most probably be, an aneurism, the operation for which, must be done by tying the artery above and below the puncture. The cases which have of late occurred, establish the propriety ofthi*. operation, instead of that, of only tying the artery above th& wound. This same accident has occasionally produced the varicose aneurism, but not so frequently as the common aneu- rism ; the progress and appearance of which, nearly corres- ponds with the following description : * If a little size injection be thrown into the veins, will more easily be made. 344 When the young surgeon opens the artery,* he, in great alarm, applies a firm compress and roller; by which, the ex- ternal wound, and that of the fascia, soon heal ; but the ar- tery will continue to bleed, though not outwardly ; the blood will be impelled under the fascia ; the connexions of the fas- cia will be torn up ; a regular tumour will be formed, occupy- ing the bend of the arm : and this tumour, stretching the fascia, will contract the fingers, and keep the fore arm at a right angle with the arm, as in other diseases in which the fascia is contracted, or the muscles under the fascia infla- med. "By observing the anatomy of the parts here, we shall see the danger of tying the median nerve along with the artery; and the difficulty there would be, in separating the nerve from the artery, if the arm be kept extended. We shall al- so see the danger of cutting off cither the radial or ulnar ar- tery, if, in operating here, we dissect too boldly. The ques- tion of the inosculations between these several vessels, should now pass through our minds. Nor should w T e forget the irregularities, that must occur in the vessels here, when there is a high bifurcation of the humeral artery. A very serious accident sometimes occurs in bleeding, which our knowldege of anatomy will hardly enable us to avoid, the puncture of one of the cutaneous nerves. When we examine the connexions of the internal cutaneous nervff with the median basilic, we shall see, that the principal branches pass under the vein ; but if we look to the median, and cephalic, we shall find several large branches from the external cutaneous, passing over them. This view should induce us to prefer performing the operation of bleeding in the median basilic vein, for, with a little care, and a sharp lancet, the artery (which is immediately below it) may be avoided : but the most dexterous surgeon may prick one of the nerves; the consequence of this, are sometimes terrible. We should now pay particular attention to the relative position of the arteries and nerves in the middle of the fore wrm ; for the arteries are of such a size, that, when wound- ed, they will in general require to be tied. The radial artery, at about one-third down the arm, may be sought for, by first cutting through the thin fascia. By * The superficial seat of the artery, and its contiguity U the vein, causes the blood to flow sometimes from the vein, per saltum ; which circumstance has given a pale face to ma- ny a youth, conceiving it to be the blood leaping from a wound of the artery. The pulsation ceases upon bending ? he 'arm a little. 345 then raising the edgaof the supinator longus, a second fas* da will be seen, covering 1 the artery as it passes over the ten- don of the pronator teres. The same artery, near the wrist^ will be found between the flexor carpi radialis, and the supi- Hator longus ; it is covered Jay a fascia * ? a considerable branch of the muscular spiral nerve will be seen on its radial side; and a smaller one, from the external cutaneous, almost im- mediately over it ; both of these nerves, are superficial to the fascia. The artery will be found on the back of the hand, between the extensor muscles of the thumb, but here it lies deep ; abranch of the muscular spiral nerve crosses it. The ulnar artery, about the middle of the fore arm, will be found between the flexor carpi ulnaris, and flexor digito- rum sublimis, but rather under the flexor sublimis. The ulnar nerve lies on the ulnar side of the artery. In looking for the artery, near the wrist, we should raise the fascia which binds down the tendon of the flexor carpi ulnaris; on holding aside the tendon, we shall see another fascia, and upon cutting through this, we shall find the artery. The nerve is rather more under the tendon, but still very close to the artery. These are very important points to attend to, for I have seen a great deal of mischief arise in consequence of an at- tempt to stop the bleeding, of even the superjicialis voice, by compression. Two cases, in which this small artery was wounded, 1 well remember. A drunken fellow, in fighting 1 , drove his arm through a pane of glass; the superficialis vo- lae was cut, and so near to the main trunk, that it was impos- sible to tie the stump of the artery. The radial was tied ; but, in consequence of the many ineffectual attempts, which had been made in chemist's shops, by compression, applica- tions of turpentine, &c. the wound did not heal kindly ; and the man being of a dissolute habit, gradually sunk. About twelve months ago; I was called to the daughter of a respect- able tradesman, who, in cutting bread, wounded the superfi- cialis voice. It would appear, that the artery had bled vio- lently ; as she had been, during the course of two hours, sent from shop to shop, until at last, after having lost about two pints of blood, she found one druggist bolder than tho others; who, however, to stop the haemorrhage, resorted to such means as injured the arm so much, that I found great difficult ty in saving it.* * A surgeon in the country will find, that an arm, which jias been only partially dissected, if preserved in spirits, (and so that it may be taken out of the jar for examination,) will to much more useful tQ him, than the finest display 346 , \ To impress upon the student the importance of the study of the surgical anatomy of the fore arm, I shall here intro- duce what Mr. Charles Bell has said, in his System of Dis*- sections : " Of the Ulnar and Radial Arteries at the WrivL There is no part of the body in which it is more necessary to con- nect the anatomy with the accidents, than here at the wrist; for, from apparently slight accidental wounds of these arte- ries, there come great pain, inflammation, deep driving, of the blood, unskilful operations, and bad surgery, and dan- ger of losing the arm, and even the life of the patient. The danger is from these vessels, the Ulnar Artery, as it turns aver the wrist, and the Radial, as it turns over the root of the thumb, or the Palmar Arch in the hand, not being neatly tied at iirst. The consideration of this department of surgerywould lead us too far ; I only say, look to it now, when the parts are before you. I would beg you also, to look to the pecu- liar appearance of the fat, and the aponeurosis on the palm. " In a wound of the artery in the palm, we put in a large pad or compress, and close the hand, and bind it firmly ; but if the arch of the palm be cut, this does not completely stem frhe blood, or the pain and inflammation are such, as will not allow the bandage to be drawn sufficiently tight : we must then undo the bandage, and endeavor to find the arte- ry ; but the appearance of the wound is changed: it is tu- mid, and the cellular membrane stuffed with blood, so that, from the confusion, we probably cannot see the mouth of the artery. In this state of things, the patient getting weak from loss of blood, and the vessels perversely bleeding, only when the dressings are applied, and stopping when they are undone, the surgeon is tempted to follow the artery with in- cisions, fruitless perhaps, because he is still amongst the dis- ordered parts. He is at last tempted to dive for the roots of those vessels with his needle. And now let us observe the consequence of this. Suppose that a surgeon does not dis- sect neatly for the radial or ulnar artery at the wrist, but plunges for it with his needle, the skin, tendons, and nerves are- included, and the ligature is drawn tight upon them; minute branches of the arteries. Such a. preparation will not be very expensive, nor will it be difficult to preserve. After the blood has been pushed out of the vessels, a mixture of proof spirit, saturated with alum, should be injected into them. A liquid composed of two-thirds of proof spirit to one of distilled water, saturated with alum, will then be suffi- ciently strong to preserve the arm ; it mav be cut through at the middle of the biceps, and at the middle of the fore arm-. 347 there maybe most dangerous nervous symptoms from the "in- cluding of the nerve, or, more certainly,the next day, by the fading of the parts, the ligature slackens, and the artery bleeds again. " When the student then, is. studying this part of the anat- omy, let him not run with too much rapidity over this im- portant lesson. I would recommend it to him to read Mr. John Bell's Principles of Surgery, upon this point, where ho will find surgical cases so pictured and represented to him, that he will not quickly forget them; let him return then again to his subject ; let him examine the fascia at the fore part of the wrist, and the manner in which it covers the arte- ry : let him observe the palmar aponeurosis, and mark accu- rately, the place at which the arteries turn over the wrist { let him mark the connexion of the ulnar artery and nerve, where they lie connected, and observe the radial nerve fre from the arteries, passing under the ligament of the wrist, and then he will not be guilty of seeking the radial nerve, in Border to separate it. from the radial artery." The situation of the nerves should be accurately marked '; lor ases occasionally occur, which may induce us to cut the branch of one of the nerves ; but the propriety of such an operation, is very questionable. We must not do it in a per- son who has the slightest symptoms of hysteria, as such cases will probably be very muc& aggravated by the operation. I was lately induced, by certain very distressing symptoms, which were distinctly referable to a small tumour in a branch of the radial nerve, to extirpate the tumour; but though the local symptoms were removed by the operation, still I would not like to repeat it ; for though my patient had never pre- viously been hysterical, she was affected, for several days -succeeding the operation, by a set of symptoms, which though not actually alarming, were very unpleasant. After removing the muscles, the joints should be particu- larly examined with reference to the subject of dislocation. In this inquiry, the student will find much assistance in thfc plans of the different dislocations, which are given in the operative surgery, by Mr. Charles Bell. 348 DISSECTION OP THE LYMPHATICS. THE dissection of the lymphatics is very easily made when they are injected; but to do this, is perhaps one of the mdst riifficut operations of Practical Anatomy. We require for it very delicate instruments ; those which are sold in the shops, and which are depicted in Sheldon's Work on the Absorbents, are better than the fine drawn glass "which is recommended by the continental anatomists ; for though the glass tube may be made very small, still it is so liable to break, that it is a constant source of vexation. Professor Dumerel has proposed to show the lacteals, by injecting them with milk, and then putting the injected por- tion of intestine into a weak acid, by which the milk will be coagulated ; but the best view of these vessels may be given by a method, which a man may be permitted to do for once, viz. that of tying the thoracic duct of an.animal which has Been fed, about half an hour previous to its death, upon meal find milk : there is no necessity for the cruel experiment of tying the duct, and opening the animal while alive ; for, as the action of the absorbents continues for a short time after the animal is deprived of sensibility, if the duct be then tied, the lacteals will become distended. In the injection of the lymphatics for a preparation, our success depends, perhaps, more on the body we choose than on any other circumstance. It has commonly been said, that dropsical bodies are the best for making lymphatic pre* parations from ; but it will be found, that bodies only slight- fy anasarcous, if they be emaciated, are much better. In a patient dying of consumption, or of any disease by which the fat of the body has been absorbed, we shall perhaps succeed better than in any other. It is not merely on finding the lymphatics, and filling them with mercury, (for this may be done in almost any body,) that the success of the preparation depends, but also on the quickness with which the parts can "be dried, after the vessels are injected. In consequence of the valvular structure of the lymphat- jes, it is necessary to inject from the extremities, toward* 349 .link. In injecting an arm or leg, \vc ought to begin as near the ringers or toes as possible ; but we need never expect to inject the lymphatics as low down as they are re- presented in some anatomical plates. The difficulty of discovering lymphatics is owing to seve- ral causes. Though they are very small, still that does not so much constitute the difficulty as their being generally empty and transparent. It is advised, by some, to make use of magnifying glasses ; but these will be found of little or no service, as it is the transparency of the vessels that is the cause of their obscurity. Small branches of nerves, and small veiny, are very often mistaken for lymphatics : even a person of the most -experienced eye will not always discover the mistake, until he attempts to fill them with mercury. It is almost in vain for any one to attempt injecting lym- phatics without an assistant ; for there are so many thing.-, requisite, besides merely the holding of the tube in the ves- sel, that he will find he can make but little progress by him- self. It is- necessary, before beginning, for the assistant to see that there are, within his reach, sharp-pointed scissars, knives, forceps, lancets, pokers, (for tubes) needles and waxed thread, so arranged, that they can be used instantly : for it will often happen, that it will be almost impossible for either the assistant or the operator to take his eye for a mo- ment off the vessel, without losing it. It is requisite, also, .that the assistant be very dexterous; as his office is often one of greater difficulty, than that of the principal operator. Every tiling being arranged, the foot or hand is to be pla- ced in a tray, that the mercury which falls, may be caught. The foot ought to be a little more elevated than the groin, to assist the flow of the mercury towards that part. With a sharp scalpel, a portion of the skin is to be cut off horizon- tally, so as to expose the loose cellular texture ; for in this texture, are the superficial lymphatics generally situated. If we cannot find one near the toes (which is very often the case) we shall probably discover one running across the sa- phena magna, on the instep. We must then take hold of it with the forceps, and dissect it from the surrounding sub- stance (to secure the keeping of it, we should put a needle with a fine waxed thread under it.) Having still hold of the vessel with the forceps, we should snip it half across with fine scissars, and into the cut made by the scissars, introduce the fine poker which is made for clearing the pipes. We should now take, from the assistant's hand, the tube con - taining the mercury, with the stop-cock already turned, and let the stream of mercury play on the side of the poker,; f 350 which will generally so direct the stream, that it will cuter the vessel. When once we have succeeded in getting a few drops of mercury into the lymphatic, it will be easy to get the pipe into the open mouth of the vessel, and then the po- Icer may be withdrawn. There is an apparent clumsiness in this method of filling the vessels : but in this manner, the smallest vessels may be injected, when it will be found quite impossible to inject them in the old way, of puncturing the lymphatic with a lan- cet, and introducing the point of the tube into it. The scis- sors make a better kind of cut than the lancet ; though there is a great deal of nicety required in using them, as they are liable to cut the vessel completely through. The poker is of very great service, as by it, it is always possible to know* whether it is a lymphatic or a small nerve that we have got : if it be a lymphatic, the poker will pass on smoothly ; if a, nerve, it will tear it into fibres. When introduced into a. lymphatic, it holds aside the lips of the cut, so that the mer- cury passes into the vessel, by the side of it. If the vessel into which the pipe is introduced, be large, it ought to be tied, round the pipe, with the thread which was previously put under it. The mercury is to be pressed on, by the assistant, with the handle of the knife; for the injector ought never to take his eye off the pipe, but he should, accor- ding to the direction of his assistant, elevate or depress the tube containing the mercury, which will regulate the force of the injection. The mouth of the vessel ought to be mois- tened at intervals, to prevent its getting dry, which impedes the flow of the mercury. If the lymphatic into which we have introduced the pipr. has filled a considerable number of vessels on the thigh, tln> mercury is then to be pressed on to the glands in the groin, taking care that the foot is not too much elevated ; as by that, the column of mercury would be raised higher than the ves- sels in the glands could bear, especially as the lymphatic* there, seem to be more easily burst, than at any other psrt. We should now withdraw the pipe, and look for other lym- phatics on the ancle, and proceed with them in the same man- ner. fr the glands are not completely filled, we ought to endea- vour to find the vessel that has the most influence in filling* each gland, for there generally appears to be one vessel which fills the gland more quickly than the others ; and at- ;r securing the other vessels, we should fill the gland from If we wish to make a good display of the glands at th'.t n, we ought to tie the seconclarv vessels arising frcin 351 i.hem ; as the mercury often passes into tlic secondary ves- sels, before it fills the gland itself. The vessels ought to be dissected and dried as quickly as possible ; for if the limb becomes putrid, the mercury in the lymphatics is liable to become black. After exposing them, and before they are dried, they ought to be tied at regular intervals ; they should always be kept in the horizontal po- sition, as they are liable to burst when dry, if held perpen- dicularly. We may generally succeed in injecting the lym- phatics of the liver, or the lacteals of the intestines, by mere- ly puncturing the vessels with the lancet ; for there is here, u surface opposed to the vessels, which keeps them more steady, than those in the limbs. By blowing air into the lymphatics, we may inject them more easily f but there is always the disadvantage attending this method, that the air prevents the flow of \he mercury into the glands. These preparations are attended with so much trouble in the making, that it is of some consequence to be able to pre- serve them. If we endeavour to do this, by merely varnish- ing and drying them, we shall soon see our labour defeated ; for the change from the horizontal position, or a change of temperature, will, in all probability, burst the vessels. By preserving them in spirits of turpentine, we shall riot only avoid the changes of temperature, and the destruction by in- sects, but add much to the beauty of the preparations. (a) (a) The lymphatics, for the most part, take the course of the veins from which we have a superficial and a deep seat- ed set. The superficial lymphatics run immediately under the common integuments: those of the extremities are on the inner side of the limb, and are more numerous than the veins in those places situated. The deep seated absorbents accompany the ramifications of the large arteries, and are lull double their number. The student, by a reference to some system of anatomy, will acquaint himself with the course of the absorbents throughout the body before he may attempt the injection of a single limb. He should be well acquainted where to look for these vessels, since, when exposed to the eye, they are with such difficulty distinguished. While on the examination of the parts concerned in femo= ral hernia, the student, if he introduce the pipe into the lym- phatics at the inner pait of the thigh, where the vessels are large and easily found, may nave a sight of the superficial absorbents, that, by perforating the crural sheath; give the 352 appearance called cribriform portion of that sheath. From this source, by a little care, the glands of the groin may be filled, and all the trunks of the absorbents seen as -they pass under Poupart's ligament. By this he will be able to see the part by which a femoral hernia appears at the upper part of the thigh, and have a full view of the cause that weakens the sheath at its inner and upper part. EXPLANATION OF THE PLATES, INDEPENDENTLY of the truth or philosophy of Mr. BellV observations on the nervous system, we have at present t< consider it as an arrangement merely, as a plan -for facili- tating the acquirement of a knowledge ofthe nerves. When we contemplate the dissection which we have made ofthe nerves of the face, neck and chest, and arc lost in the confusion ofthe Vllth, VHIthand IXth, of the branches of the cervical nerves, ancl of the sympathetic, ofthe diaphrag- matic and spinal accessory nerves, we shall be prepared to eee the advantages ofthe plans which are annexed. I think the student will soon discover that the system, of which the plans may give him some idea, is not only a most remarkable improvement in the knowledge of the structure and func- tion of animal bodies, but is of the greatest use in practical anatomy, by facilitating the comprehension of a very useful, department. The principal arrangement is this : there is an obvious division of the medulla spinalis, corresponding to the cere- brum and cerebellum ; every Regular Jferve has two roots, one from the anterior of these columns, and another from the posterior. Such are the Vth pair ; the Suboccipital ; the Seven Cervical ; the Twelve Dorsal ; the Five Lumbar ; ancl the Six Sacral^ viz. thirty-two Perfect, Regular, or Double vVerirc.y. These are laid down in 'the first plan. They are common to all animals, from the/worm up to man ; ami are for the purposes of common sensation and motion, or voli- tion. They run out laterally to the regular divisions of the body, and never take a course longitudinal to the body. For the sake of an arrangement (although the term be not correct where every thing is perfect,) the remaining nerves are called Irregular Nerves. These are distinguished by a simple fasciculus, or single root; that is, a root from on* column. These are imperfect in their origins, irregular m their distribution, and deficient in that symmetry which char- acterizes the first class. They are superadded to the origi- nal class, and correspond to the number and complication o; the superadded organs. Of these, there are the Hid, IVth, and Vlth, to the eye ; the Vllth, to the face; the IXtli 354 1 he tongue; the Gfosso Pharyngeal, to the pharynx ; the Vagus, to the larynx, heart, lungs, and stomach ; the Phre- nic, to the diaphragm ; the Spinal Accessory, to the muscles of the shoulder ; the External Respiratory, to the outside of the chest. If we inquire into the reason of this seeming confusion in the second class, or irregular nerves, we shall perceive, that it is owing to the complication of the superadded apparatus of respiration, and the variety of offices which this apparatus has to perform in the higher* animals. To explain this, the second plan is given. It presents, in one view, the nerves' destined to move the muscles in all the varieties of respira- tion, speech and expression. We may now see how confounding the nwnbcruig of the nerves, according to the system of Willis, is ; and how im- possible it is to make a natural arrangement, while the nerves are so numbered. PLATE I. A. A. Cerebrum. B.B Cerebellum. C.C. Crura Cerebri. D.D. Crnra Cerebelli. E.E.E. Spinal Marrow. 1. 1. Branches of the Vth pair, or Trigemimis, which are seen to arise from the union of the Crura Cerebri and Crura Cerebelli and to have a ganglion at the roots.. 3. 2. Branches of the Subcjccipital Nerves, which have double origins and a ganglion. 3. 3 The branches of the four Inferior Cerviclc Nerves, and of the first Dorsal, forming the Axillary Plexus : the ori> gins of these Nerves are similar to those of the Vth and the Suboccipital. 1. 4. 4. 4. Branches of the Dorsal Nerve. c ; which also arise in the same manner. 3. 5. The Lumbar Nerves, &. 6. The Sacral Nerves. 355 PLATE" IL A. CEHEBBVM. B. CEREBELLUM. C.C.C. SPINAL MARROW. D. TONGUE. E. LARYNX. P. LUNGS. G. HEART. H. STOMACH. I. DIAPHRAGM. 1.1.1. PAR VAGUM, arising by a single set of roots, am! passing to the larynx, the lungs, heart and stomach. 2. Superior Laryngcal Branches of the Par Vagum. 3. Recurrent, or Inferior Laryngeal of the Par Vagum. 4. Pulmonic Plexus of the Par Vagum. 5. Cardiac Plexus of the Par Vagum. 6. Gastric Plexus, or Corda Ventriculi of the Par Vagurn. 7. RESPIRATORY NERVE, or Portw Dura, to the Muscles <*.' the Face, arising by a series of single roots. 8. Branches of the GLOSSO PHARYNGEAL. 9. LINOTTALIS, sending branches to the Tongue and to UK Muscles on the forepart of the larynx. 10. Origins of the SUPERIOR EXTERNAL RESPIRATORY, or 8pinal Accessory. 11. Branches of the last Nerve, to the Muscles of the shou"! der. 12. 12. 12. INTERNAL RESPIRATORY, or the Phrenic, to thr Diaphragm. The origins of this nerve may be seen lit pass much higher up, than they are generally described. '3. INFERIOR EXTERNAL RESPIRATORY, to the Muscles' on therid&cfthe Chest. FINIS. U.C. BERKELEY LIBRARIES ,1