/. ex MEDICAL SCHOOL Medical Library Exchange Washington University Scho of ^edicine Library iltrfrind ^ e) 'j;< [ OF X 3 z E D i C A L D E PT ^ashington (j ^p»H6?Sy A .ABORATORY OF HUMAN ANATOMY ' LEWELLYS F. BARKER, M.B. TOR. PROFESSOR AND HEAD OF THE DEPARTMENT OF ANATOMY IN THE UNIVERSITY OF CHICAGO AND RUSH MEDICAL COLLEGE ASSISTED BY DEAN DE WITT LEWIS, A.B., M.D. AND DANIEL GRAISBERRY REVELL, A.B., M.B. INSTRUCTORS IN ANATOMY IN THE UNIVERSITY OF CHICAGO ILLUSTRATED PHILADELPHIA AND LONDON J. B. LIPPINCOTT COMPANY 1904 COPYRIGHT, 1904 BY J. B. LIPPINCOTT COMPANY ELECTROTYPED AND PRINTED BY J. B. LIPPINCOTT COMPANY, PHILADELPHIA, U.S.A. Hot PREFACE MANY instructors in anatomy have for some time felt the need of more systematic, more orderly, and more thorough work in the dissecting-room. Anatomy, one of the first sciences to be taught by the laboratory method, has not always kept pace with her younger sister sciences in the advance of methods of instruction. A number of laboratory manuals are, it is true, available ; but it has been complained that even the best of these is unsatisfactory, partly on account of nomenclature, partly because so much is included that the student tends to lean entirely upon his manual, rather than to observe at first hand for himself and to consult larger text-books and atlases. So convinced have some anatomists become of the inadequacy of present manuals that they have banished all dissecting guides from their laboratories, and insisted upon their students work- ing with no guide whatever except large atlases and text-books and occasional hints from the instructor. This latter plan has worked very well in some instances, especially where men enter- ing upon the study of medicine had previously undergone rigid laboratory training in physics, chemistry, and biology. But even such men had to pass through a period of doubt, perplex- ity, and discouragement before they became independent dis- sectors, and some of them completely failed to do so. Students without such preliminary training in science are very apt to be utterly lost if thrown entirely or almost entirely upon their own resources, especially where classes are large and more than ten students have to be cared for by one instructor. It is believed that the use of the Laboratory Manual here presented will enable the good student to become an independent worker much more quickly than wien b^. is left without such guidance ; he will be able to do his wora in less time and can assure himself that he is doing it thoroughly, using the Manual, if he prefer, merely as a control of his work ; at the same time the student who is less well-equipped will be gradually led into independent work, to which he might otherwise never attain. There should be also a marked saving of time and energy for the instructor, a matter of no little importance if he is to make vi PREFACE contributions to knowledge by original investigation in his department. There is no intention, however, to make " word of mouth" instruction superfluous. On the contrary, it is hoped that the use of the Manual will make it possible for the in- structor to concentrate his attention upon, and to give better than before, that particular help to the student which comes alone through the personal encounter. Whether the effort to find the golden mean between the " spoon-feeding" guide, on the one hand, and insufficient guid- ance, on the other, has been successful must be left to anatomical teachers to decide. The compilers have used the Manual in mimeograph form during the past year in the Anatomical Lab- oratory of the University of Chicago ; instructors and students both feel that it has been distinctly helpful. The sequence of dissection and the methods of exposing the various parts are those almost universally adopted in the better English and American laboratories. They represent the expe- rience and traditions of more than a hundred years of careful anatomical work. The influence of the Edinburgh school of anatomists has become widespread, and the directions of one of the principal representatives of that school, Professor D. J. Cunningham, of Edinburgh, as embodied in his admirable Manual of Dissection, have been closely followed herein. The Laboratory Manual is not intended to take the place of a descriptive text-book (see p. 30) ; on the contrary, it is hoped and expected that it will act as a stimulant to the student not only to use in connection with it the best descriptive text-book and atlas available, but also to refer to various atlases and text- books, as well as original articles in the literature. Though it is realized that the average medical student has not the time to range far afield, it would seem highly desirable that he should at least gain an idea of the wide extent of the subject and that he should learn that it is not all included between the covers of a dissecting manual. The nomenclature employed is that which was formulated by the German Society of Anatomists and which is rapidly being adopted in many of the best English and American laboratories. There seems to be no doubt that this nomenclature will be the prevalent one for at least many years to come. The magnificent atlases of Spalteholz and Toldt, which have recently been pub- lished, employ it exclusively, and the student will find it a great convenience to have the terms used in his laboratory manual identical with those of his atlas. Unfortunately, only one or PREFACE vn two of the most recent descriptive text-books of systematic human anatomy by English writers have yet adopted this nomen- clature. It is earnestly to be hoped that an advance will quickly be made in this direction and that text-books will employ it uni- formly. Special attention is drawn to the fact that in the fol- lowing Laboratory Manual the old terms, when different from the new, have been added in parentheses, so that the student need never be embarrassed in finding his way even in a de- scriptive text-book or atlas in which only the old terms are employed. He is advised, however, when purchasing a text- book to give preference to one in which the new nomenclature [BNA] is consistently employed. Indulgence is asked for misprints and errors almost certain to occur in the first edition of a work including such an enor- mous number of names as is involved in a subject like human anatomy. Should the Manual find enough friends to make a second edition desirable, many improvements can doubtless be made, and suggestions from instructors and students of anatomy will be cordially welcomed. The Manual contains about 300 illustrations, of which a special index is given. The drawings and plates represent in a very satisfactory way the most important structures of the body. These illustrations have been chosen to serve as a valu- able atlas to students who feel that they cannot afford to buy one of the more expensive atlases like those of Spalteholz and Toldt. On the other hand, students who own Spalteholz 's At- las, the one especially recommended for use in connection with this Manual, will find that the illustrations have been selected with the special aim of supplementing those of Spalteholz, and that they will prove a valuable addition to the latter. The Anatomical Atlas of Toldt, from which many of the illustrations in this Manual have been borrowed, can be very highly recommended; every student who can afford to do so should purchase it for his library. CHICAGO, October 1, 1904. TABLE OF CONTENTS ¥¥ INTRODUCTION PAGE GENERAL 17 INSTRUMENTS 19 PRESERVATION OF THE PART 24 CLOTHING 26 DRAWING 26 BOOKS 30 Library 30 DIVISION OF THE CADAVER INTO PARTS 34 ANATOMICAL TERMS OF POSITION AND DIRECTION 34 GENERAL ANATOMICAL TERMS . . 36 Part I. UPPER EXTREMITY. ARM AND WALL OF THORAX 41 SURFACE ANATOMY 41 REGIONS OF THE BACK 45 ANTERIOR THORACIC REGION AND AXILLARY FOSSA 51 REGION OF THE SHOULDER 68 ARM AND FOREARM 73 SHOULDER- JOINT 84 FOREARM AND HAND 87 WRIST AND PALM 96 DORSAL SURFACE AND RADIAL MARGIN OF FOREARM 104 DORSUM OF WRIST AND HAND 106 JOINTS . 109 Part II. LOWER EXTREMITY. INTRODUCTORY 121 GLUTEAL REGION 123 POPLITEAL FOSSA 129 POSTERIOR SURFACE OF THIGH 135 ANTERIOR SURFACE OF THIGH 138 MEDIAL SURFACE OF THIGH 152 HIP- JOINT 154 LEG AND FOOT 156 ix x CONTENTS PAGE LATERAL REGION OF LEG 163 MEDIAL REGION OF LEG 165 POSTERIOR REGION OF LEG AND HEEL 165 PLANTAR REGION OF FOOT 174 KNEE-JOINT 180 TlBIOFIBULAR JOINTS 184 ARTICULATION OF THE FOOT 185 ARTICULATIONS OF TOES . . 190 Part III. HEAD AND NECK AND DORSUM OF TRUNK. SCALP 194 OPENING THE CAVITY OF THE SKULL 197 REMOVAL OF BRAIN 199 SIDE OF NECK 204 MEDIAN LINE OF NECK 222 BACK OF HEAD, NECK, AND TRUNK 228 THE SPINAL CORD 242 FACE 247 TEMPORAL REGION AND RETROMANDIBULAR FOSSA 260 PTERYGOID REGION AND JOINT OF JAW 261 MANDIBULAR CANAL AND SUBMAXILLARY REGION 264 DEEP DISSECTION OF NECK 267 MIDDLE CRANIAL FOSSA 272 ORBIT 275 REGION IN FRONT OF CERVICAL SPINE 282 LIGAMENTS OF VERTEBRAL COLUMN AND SKULL 286 MOUTH AND FAUCES 288 PHARYNX 291 CAROTID AND INFRAORBITAL CANALS 297 SAGITTAL SECTION OF FOREPART OF HEAD NEAR MEDIAN PLANE 298 Otic Ganglion 299 Cavity of Nose '. 300 Sphenopalatine Ganglion 303 Intraosseous Course of some Cerebral Nerves 305 LARYNX 307 TONGUE 315 BRAIN 317 Membranes of Brain 317 Blood- Vessels of Brain 318 Removal of Meninges and Superficial Blood- Vessels 322 Cerebral Nerves 322 Larger Subdivisions of the Brain 324 External Morphology of Rhomboid Brain and Midbrain 326 Medulla Oblongata 326 Pons [Varolii] 327 Isthmus of Rhombencephalon 327 Midbrain 328 Cerebellum 328 Fourth Ventricle . . 330 CONTENTS xi PAGE BRAIN : External Morphology of Forebrain 331 End-brain 332 Hemisphere 332 Brain Mantle 332 Lobes of Cerebrum 333 Medial Surface of Hemisphere 336 Island 337 Olfactory Brain 337 Hypothalamus 338 Corpus Callosum 338 Lateral Ventricle 339 Septum Pellucidum 343 Fornix 343 Thalamencephalon 346 Third Ventricle 346 Sections through Brain 347 Sections of Medulla Obiongata 347 Sections of Pons 353 Sections of Cerebellum 354 Section of Rhombencephalic Isthmus, Corpora Quadrigemina, and Cerebral Peduncle 356 Sections of Hypothalamus 360 Sections of Thalamencephalon 362 Sections of Telencephalon 362 Conduction Paths of the Nervous System 364 Descending and Ascending Fibre Systems in Spinal Cord 365 Fibre Systems of Cerebral Nerves 365 Conduction Paths of Cerebellar Peduncles 369 Conduction Paths of Diencephalon and Telencephalon 372 Projection Fibre Systems 372 Associative Fibre Systems 373 ORGAN OF VISION 375 Introductory 375 Fibrous Coat of Eye 376 Sclera 378 Cornea 378 Vascular Coat of Eye 379 Chorioid 379 Ciliary Body 379 Diaphragm of the Eye (Iris) 380 Layer of Pigment 381 Retina 381 Vitreous Body 382 Ciliary Zonule 383 Crystalline Lens 383 Chambers of Eyeball 384 ORGAN OF HEARING 384 Introductory 384 External Acoustic Meatus 385 Cavity of Tympanum 385 xii CONTENTS PAGE ORGAN OF HEARING: Membrane of Tympanum 387 Tympanic Mucous Membrane 388 Auditory Ossicles 388 Joints and Ligaments of the Auditory Ossicles 390 Muscles of Auditory Bones 391 Osseous Labyrinth 391 Membranous Labyrinth 394 Part IV. THORAX. (WALLS AND VISCERA.) INTRODUCTORY 399 INTERCOSTAL MUSCLES 399 INTERCOSTAL NERVES 400 INTERCOSTAL VESSELS 401 INTERNAL MAMMARY ARTERY 402 TRANSVERSE MUSCLE OF THORAX 402 THORACIC CAVITY 403 PLEURA 403 EXPLORATION OF PLEURAL CAVITY 405 REMOVAL OF CENTRAL PORTION OF STERNUM 407 LUNGS 407 ROOT OF LUNG 408 PHRENIC NERVE AND CARDIAC PLEXUS 409 PERICARDIUM 410 THYMUS 411 GREAT VEINS OF THORAX AND THEIR TRIBUTARIES 411 HEART AND AORTA 412 TRACHEA AND BRONCHI 424 POSTERIOR MEDIASTINAL CAVITY AND ITS CONTENTS 424 INTERIOR OF THE LUNGS 426 THORACIC PORTION OF SYMPATHETIC NERVOUS SYSTEM 428 WALL OF THORAX FROM WITHIN 428 JOINTS OF THORAX . 429 Part V. ABDOMEN AND PELVIS. INTRODUCTORY 433 PERINEAL REGION 434 MALE PERINEUM 436 UROGENITAL REGION IN THE FEMALE 444 ANAL REGION AND DIAPHRAGM OF PELVIS IN BOTH SEXES 449 ANTERIOR ABDOMINAL WALL . . 451 CONTENTS xiii PAGE PERITONEUM AND ABDOMINAL VISCERA 462 Developmental Relations 462 Great Omenturn 467 Lesser Omentum 468 Mesentery 468 Mesocolon 468 Mesorectum 469 Fossae and Plicae 470 Omental Bursa 472 Peritoneal Ligaments 472 Superior Mesenteric Artery 474 Superior Mesenteric Vein 476 Superior Mesenteric Plexus 476 Inferior Mesenteric Vessels and Nerves 477 Small Intestine 479 Large Intestine 485 Structures in Lesser Omentum 489 Coeliac Artery 491 Duodenum 492 Pancreas 495 Vagus 497 Stomach 498 Abdominal Sympathetic 500 Spleen 501 Liver 502 Gall Bladder 505 UROPOETIC ORGANS 505 Kidney 506 Ureter 509 Suprarenal Glands 509 MUSCLES AND VESSELS IN THE ABDOMEN 511 NERVES IN THE ABDOMEN 516 DISSECTION OF THE MALE PELVIS 519 Peritoneal Folds 519 Hypogastric Plexus 519 Pelvic Fasciae 520 Rectum 524 Urinary Bladder 525 Prostate 525 Seminal Vesicles 527 Deferent Duct 527 ARTERIES OF THE PELVIS 528 VEINS OF THE PELVIS 533 MUSCLES AND NERVES OF THE PELVIS 533 PELVIC VISCERA 536 Rectum 536 Urinary Bladder 537 Male Urethra 539 Wall of Seminal Vesicle 539 DISSECTION OF THE FEMALE PELVIS 540 Peritoneum . 541 xiv CONTENTS PAGE DISSECTION OF THE FEMALE PELVIS: Hypogastric Plexus 541 Pelvic Fascia 541 Vessels and Nerves 542 Rectum 542 Bladder 543 Ureter 543 Uterus 543 Vagina 545 Ovary 546 Uterine Tube 546 Round Ligament 547 Diaphragm of Pelvis 547 Rectum 548 Urethra 548 Interior of Vagina 549 Interior of Uterus 549 Interior of Uterine Tube 550 JOINTS OF THE PELVIS 551 INTRODUCTION THE anatomical laboratory has the longest history of all the medical laboratories. The student has the experience of hun- dreds of years to draw upon. The best methods of isolating the various structures have been worked out and certain rules for dissection have been formulated; the student will do well to familiarize himself with these as early in his course as pos- sible. Careful, practical work in the dissection-room is the only means the medical student has of obtaining an independent view of the gross structures of which the human body is composed. Text-books, atlases, demonstrations, and lectures are useful aids, helpful in exciting interest, and favorable to the acquisition of powers of description and illustration; but the main part of the work in anatomy should consist of the student's personal observation. He should learn to see what comes under his eye. He should try by his own independent activity to see all that is there, for the student who learns to see only what he is told to see or what is pointed out to him will be spoiled for the study and practice of medicine. Many students in the past have entered the dissecting-room with an utter lack of independent power of observation, of ex- amination, and of description, and yet these three qualities are absolutely necessary for the man who is to engage successfully in the practice of medicine. While it is to be hoped that the advance in the requirements for admission to professional schools, leading as it does to observational work in physics, chemistry, and biology preliminary to the work of the medical course, will bring the students to our laboratories of anatomy better prepared than hitherto for the independent observation of anatomical structures, there can still be but little doubt that many students will learn how really to study and observe first in the dissecting-room. How important it is that the habits formed at this early period of the professional course should be such as will be of value to the student later, such as he would desire to have throughout his professional career ! If he have learned to be exact and steady, systematic and thorough, cleanly 2 17 18 INTRODUCTION and artistic, in his work in the dissecting-room, how much better for him than if at the outset of his career he become satisfied with superficial observation, with interrupted and irregular activity, with disorder and uncleanliness ! The habits formed in the anatomy building have their effect upon the whole life of the physician. Moreover, the very first dissection may be all-important as regards the subsequent dissections. He who fails in his earliest dissection to acquire the habit of working according to a definite method seldom learns later to become an exact, quick, and careful dissector. It is almost hopeless to try to make a man do exact and clean work in the dissecting-room after he has once formed inaccurate and dirty habits. The student in the beginning should aim not so much at rapidity as at method. When he has once formed the habit of proceeding always according to a care- ful method, the rapidity will quickly follow. It is sometimes asked, " Why should the medical student spend so much time and take so much pains in making a careful and beautiful dissection? Is it not time wasted to work out the smaller branches of the nerves and blood-vessels?" Expe- rienced teachers who require thorough work are not disturbed by such inquiries. Those who have had the best opportunity for judging assert that it is only when a man succeeds in making a fine dissection that he gains an interest and pleasure in an occupation which may not at first be attractive to him. Further, the importance of working out the finer structures lies not always so much in the actual knowledge of these structures gained by the student, as in the acquisition of the habit of thor- oughness of observation and investigation. The medical student who in the dissecting-room dissects out only the main trunks of the vessels and nerves, or only the structures which at the moment seem to physicians and surgeons of greatest practical import, is likely as a clinician to be satisfied with the detection of the more obvious and superficial symptoms, to the overlooking of the less prominent symptoms and the more obscure physical signs. The thorough dissector is much more likely later to become a finely discriminating physician and an effective pro- gressive surgeon. Again, if a dissector permit himself to expose structures roughly, to isolate them incompletely, and to clean them imperfectly, so that his dissection becomes indistinct, bad- smelling, and repulsive-looking, he will quickly lose interest in his work, slice the part desperately, neglect it, stay away from it, and fail utterly to benefit by it. Each student should, therefore, INTRODUCTION 19 at the beginning, err, if at all, upon the side of over-exactness and over-carefulness in the use of instruments, in the methods of handling anatomical objects, and in the isolation of the details of structure. He should at first force himself to follow estab- lished rules and regulations rigidly ; if desirable, later on in his work he may allow himself more latitude. He should aim to make his dissection such that he may at any moment and without embarrassment turn it over to an instructor who may wish to deliver a lecture on the part; he should aim to do his work so carefully that an artist may satisfactorily make a drawing of it to illustrate a text-book. While a large portion of the student's time in the early part of the dissection is occupied with the technique of the work, learning how to find the various structures and to demonstrate them properly, he should not forget that the mere mechanical side of the work, important as it is, is not the only side. It is necessary that he should also study the structures carefully, learn their names, examine their relations, and, above all, under- stand their significance. Atlases, text-books, models, and moist and dry preparations should be assiduously used in connection with the dissection of the part, if the student is to acquire in the anatomical laboratory the knowledge and skill which it is de- sired that that laboratory shall give him at the beginning as a basis for his other medical studies. INSTRUMENTS NEEDED. Each student should provide himself with a good set of dis- secting instruments made by a reliable manufacturer. They should be made of good steel, properly tempered and well ground. It is false economy to buy cheap instruments or to secure a set at second hand. The quality of the student's work will be much influenced by the kinds of instruments he uses and the state in which he keeps them. A good set of dissecting in- struments will not cease to be valuable to the medical student when he finishes his dissection, but will be found convenient for many purposes during his subsequent practical life. The sets supplied by the manufacturers vary greatly in ex- tent and quality, and the student may find it advantageous to make up a set for himself, choosing the individual instruments from stock, rather than to purchase any regular dissecting-case offered. As a minimum the student should possess : 20 INTRODUCTION 1. One cartilage-knife (with bellied blade). 2. Three dissecting scalpels with bellied blades, one large, one of medium size, and one small. 3. Two dissecting scalpels with straight edges and sharp points, one long and one short. 4. One pair of medium-sized scissors. 5. One pair of small scissors. 6. One blunt probe (Mall's). 7. One large dissecting forceps. 8. One tubulus or blowpipe. 9. One sound (fishbone or metal). 10. One good curved needle and sutures. 11. One good razor-strop. 12. A medium-sized sponge. Other instruments, including mallet and chisels, saws, rhachi- otome, myelotome, enterotomes, and bronchial scissors, will be supplied by the laboratory. The student may find it desirable to have more scalpels than are required above ; if so, he will find it best to have more belly- bladed knives than knives with straight edges. When purchasing forceps, the greatest care should be ex- ercised, for it is rare to find properly constructed samples. The branches should be relatively strong, not too flimsy; on closing they should come together almost with the weight of the thumb and finger, as nothing grows more tiresome than forceps which are too stiff to close easily. Forceps with well-worked-out points should be chosen, so that they will grasp fine structures with cer- tainty. The points should not slide over one another on closing. CAKE OF INSTRUMENTS. The best instruments are quickly ruined where no care is taken to prevent injury or deterioration. If scalpels and forceps are permitted to fall frequently to the floor, or if cutting instru- ments are thrown carelessly in contact with other instruments, their value as dissecting implements rapidly diminishes. Knives should be kept sharp and smooth-cutting. This is absolutely necessary if the student is to do good work, for it is impossible to dissect neatly and quickly with dull knives. The strop, if used at short intervals, — say, every ten or fifteen min- utes,— will keep a smooth-cutting edge on a sharp knife and increase its power of penetration. A knife properly sharpened and preserved from gross injury may be kept in good condition for a long time without honing or grinding if it be properly and frequently stropped. INTRODUCTION 21 When a knife becomes dulled and stropping is no longer suffi- cient to renew its edge, it should be honed. So few men learn how properly to hone a knife that it has been questioned whether students had better attempt it themselves or turn their scalpels over to an instrument-maker to be honed. Still, as one needs also to know how to keep a microtome-knife in repair, it is an advan- tage to learn to do the honing one's self. A good oil-stone or Ar- kansas stone is necessary. The knife, held obliquely, is drawn to and fro with the edge in advance, the stroke extending from the heel along the whole length to the toe of the blade. Ex- perience under some one who is skilled is very desirable, that one may know the exact angle of inclination to employ, and the point when the blade has been sufficiently honed, for after a time a continuance of the honing only does harm. Much skill and ex- perience are required to get exactly the right thinness of edge. It is to be borne in mind that dissecting knives ought not to be so thin as a surgical knife, where quick penetration is all-important and the knife is to be used only for a short period, for such knives are quickly dulled. After repeated honing a knife may lose all its thin edge ; it should then be ground. The student should avoid injuring his scalpels by cutting against bone or the end of the forceps. It is well to keep one coarse knife especially for cutting near the bone or through calcified tissues. All instruments should be cleaned and rubbed thoroughly dry before they are put away at the end of a day's work. If a dissection has been completed and the instruments are to be laid aside for some time, they should be boiled for ten minutes in a one per cent, solution of sodium carbonate, thoroughly dried, and lightly coated with clean vaseline. This sterilizes them com- pletely and helps to prevent rust. USE OF INSTRUMENTS. Scalpel. — One of the most important things for the student to learn in technique is the use of the convex or belly-bladed scalpel. This blade has a long cutting edge, and is employed for making large cuts or for cutting large surfaces; it is unsuited for small, careful cuts or for dissecting in angles or in the depth. The convex scalpel is used chiefly in dissecting the skin, fascia, and muscles, and in general where large incisions are to be made and the work is relatively gross. In the dissection of vessels and nerves, on the other hand, the larger belly-bladed UB«ARV 22 INTRODUCTION scalpels should never be used; even the smallest ones must be very carefully employed for such dissection, or important struct- ures will be injured. The scalpel with the straight edge and sharp point has a use entirely different from that of the belly-bladed knife. Although the blade of the knife with the straight edge may be quite long, one uses only the point of the knife in dissection ; the action of such a knife is, therefore, much more limited than is that of the belly-bladed scalpel, and it should be used in making only the smaller, less extensive cuts. Students are frequently seen try- ing unsuccessfully to make large incisions with such knives, especially when their convex blades are dull. The scalpel with straight edge and sharp point is especially valuable in the dis- section of the viscera, sense organs, blood-vessels, and nerves. It may well be employed whenever a small, careful cut is to be made, and it will be found of the greatest convenience when the student is working in corners or in deep fossae. The dissector should early learn the right way to hold a scal- pel. The manner of holding in the dissecting-room is quite different from that in the autopsy-room of the pathologist. In the former case and in surgical work the knife is to be held ' ' like a pen," between the thumb and the first two fingers, the handle of the scalpel pointing obliquely upward. In the post-mortem room the pathologist usually holds his knife " in his fist," the handle of the scalpel being raised only slightly above the level of the blade and resting in the palm of the hand. The only time the dissector in the laboratory of human anatomy is permitted to hold the knife " in his fist" is when he makes a long incision through tough skin ; in all other circumstances the knife should be held ' ' like a pen. ' ' The thumb, index and middle fingers should alone be used in holding the knife ' ' like a pen. ' ' The ring-finger should not be permitted to touch the knife, no matter how much the dissector is inclined thereto. Only by following this rule can the anatomi- cal workman secure the necessary freedom and acquire the deli- cacy of movement requisite to good work. The ring-finger and the little finger will be found very useful in making tissues tense, in retracting tissues, or in displacing them to the side. The scalpel should be grasped by the thumb and fingers at about the junction of blade and handle, certainly not high up on the handle, certainly not far down on the blade. In making careful cuts the hand should be supported upon its ulnar margin. This support permits of greater precision ; the cut desired may INTRODUCTION 23 be made with sureness and steadiness and without anxiety. The student should keep his finger- joints nimble, and should practise to acquire increased mobility of these joints. The skill gained in the use of instruments in the dissecting-room may be of great value in subsequent surgical practice. The importance of having several belly-bladed knives and several knives with straight edges has been referred to above. No good dissector cares to use the same knife for working out skin, vessels, muscles, nerves, etc. There should be a " division of labor" among scalpels. Hard, firm, tough tissues should be cut through only with the cartilage-knife or with a duller scalpel. Forceps. — These should be held in the left hand, " like a pen," between the thumb and first two fingers, the ring-finger and little finger being reserved for the support of the hand and never permitted to touch the instrument. The forceps should never be held * ' in the fist. ' ' They should be grasped about the middle, not too high up, and the fingers should not be cramped, otherwise the hand tires too quickly. The support of the hand on its ulnar margin by means of the little finger and the ring- finger is important, as it helps to make the work more exact and more certain. Scissors. — These should be grasped by the thumb and middle finger. The scissors are generally used where the parts to be cut through are soft, yielding, and easily displaceable and do not offer much resistance to the edge of the knife. Scissors are much employed by many dissectors in the study of the viscera and of the blood-vessels. They are especially valuable in fol- lowing out through loose connective tissue or fat the finer branches of arteries and veins, which might be more easily cut if the knife were used. Like the straight-edged scalpel with a sharp point, scissors are useful in cutting in angles or corners and in deep places. Fat held in the forceps can be most easily removed with scissors. Very fine scissors are useful in the dis- section of delicate nerves and of the small muscles of the face and orbit, but in general scissors are little suited to the dissec- tion of muscles and nerves. Probe. — The flimsy probes usually supplied in dissecting sets are of but little use and should be discarded. The firm probe devised for use in Baltimore by Professor Mall is the best one available. Many students do a very large part of their dissec- tion with this probe. It is especially useful for the beginner, who is afraid of destroying important structures with the knife. The " blunt dissection" which the probe permits of insures the 24 INTRODUCTION working out of many structures which would otherwise be cut away. In using the dissecting-probe the least force necessary to the purpose should be brought into play, the strength of the tissues being, as it were, continually tested, and the loose tissue between the definite structures being gently removed by repeated light strokes instead of by a few strong sweeps of the probe. " Wear away rather than tear away!" This will avoid giving the muscles a ragged appearance and will also preserve many small and delicate structures which would otherwise be lost. There is danger, however, of over-use of the method of blunt dissection with the probe. It is highly important that the stu- dent should gain skill with the scalpel, and this he can do only by constant practice with it. Again, where the probe is used instead of the scalpel, it is not possible to make so clean a dissec- tion as the student should require of himself. The structures are left ragged, and the artistic sense of the dissector remains unde- veloped, or, if developed, is offended. PRESERVATION OF THE PART. A large portion of the pleasure in his work and of the benefit to be derived from it will be lost if the student neglects to take proper care of the part while he is dissecting it and during the intervals between the periods of dissection. If a part be allowed to become dirty, if it be permitted to dry up, or if it become foul, the student will lose interest in it, will tire of it, and will inevi- tably neglect it. If the part has been well preserved in the first place, its preservation after arrival in the dissection-room depends entirely upon the student. If he handle it properly and protect it carefully, he can keep it in prime condition until the dissection has been completed. Drying of the part is the greatest of all dangers. The moment the tissues become dry, knives are dulled in dissecting them and it quickly becomes impossible to isolate the finer struct- ures, which, moreover, lose their natural color and form. In addition, the part grows repulsive to sight. The skin of the cadaver is one of the best protectives against drying. Skin when removed should always be kept as a covering for the part. When the dissection is put away at the end of a working period, it should be wrapped carefully in the integu- ment, which should be securely fastened by tying or pinning it in place. Some careful dissectors take the trouble to secure cutaneous flaps in position by stitches each time the part is put away. INTRODUCTION 25 In addition, the part should be thoroughly wrapped in gauze or cheese-cloth saturated with a three per cent, solution of car- bolic acid or other preserving fluid and held in place by twine. It is convenient to have a large quantity of the preserving fluid in a tub in the dissecting-room, out of which the wrappings may be wrung by hand or by a laundry wringer. The gauze or cheese- cloth should be folded into a convenient shape and size. — a few inches longer than the part to be covered and about eighteen inches wide. After being moistened in the preservative fluid, it may be wrapped about the part and secured by tapes or twine. Such a covering is readily and quickly removed when the part is required for work. It is also very useful for covering such portions as are not immediately under dissection or study. As an additional protection against drying, a piece of oil-cloth, about a foot square, is advisable for the hand, foot, and face. As soon as possible after the cadaver is placed on the table, the student should take charge of his part, wrap it up, and attach to it a label bearing his name. Not only in the intervals between the dissection periods, but also during working hours, care should be taken to prevent dry- ing. Parts not in actual use should be kept covered, for even two hours ' exposure causes drying which deteriorates the mate- rial. The portion of the dissection actually being worked upon should be moistened occasionally with a wet sponge. The best results are attainable only if the material be kept in good condi- tion; it is not possible to restore dried-out material to as good condition as it was in before drying or partial drying. Especial care should be taken to protect parts belonging to students not present. The cadaver should be kept raised on dissecting-blocks, so as to allow free drainage away of the fluids which otherwise cause the under parts to become macerated and offensive. The drain- pipe in the centre of the table must be kept unobstructed. Cleanliness about the dissection-table should be cultivated. Bits of fat and connective tissue which are removed should never be allowed to contaminate the wrappings of the part or the table itself. They should be collected on a piece of paper or cloth and then thrown into the refuse-pail. The student should leave his dissection and the dissection-table in perfect order and condition at the close of each day's work. A little care exercised in the formation of orderly and cleanly habits at this period of his development will be of great service to the student in his sub- sequent work. 26 INTRODUCTION CLOTHING. The better methods of preserving the material for dissection prevalent nowadays have removed some of the unpleasant feat- ures of the occupation. It is not possible, however, to avoid all odor or all contamination, and the student should, therefore, go to the dissecting-room clad in a manner which will permit him to work freely and without constant worry lest his clothing come into contact with the material. Hence it is necessary to have an old coat to be kept for use in the dissecting-room only, and it is preferable to change the whole suit on entering and on leaving the room. As a roomful of men garbed in old coats is not a pleasing spectacle, it is the custom in modern anatomical labora- tories to wear white cotton gowns over all. The student should, therefore, provide himself with three such gowns, so that he may always have the soiled ones laundered while the clean one is being worn. Gowns other than white should be avoided, as should the various oil-cloth sleeves and aprons formerly so much used. No inconsiderable part of the depressing influences of the old-time dissecting-room consisted of the dirty floors, the untidy tables, the tobacco-smoke, the spittoons, the oil-cloth sleeves and aprons, and the multicolored or checked gowns. Dissection is a serious task, requiring much energy and en- durance. Under the best conditions the student tires all too quickly. It is important, therefore, that the sanitary conditions of the room be the best possible, that as comfortable a position as practicable be assumed in dissecting, that the dress be one which while externally uniform throughout the room will permit of the . greatest freedom in work, and that all depressing in- fluences be as far as possible removed. DRAWING IN GBOSS ANATOMY. The student should not try to draw all that he sees, but only so much as is important in the stage represented. He should limit the contents of each picture to what can be shown clearly, and try to avoid unimportant detail. The drawing is to be made large enough to show clearly all that it contains. In general, it should be as large as the size of the drawing-paper will permit, allowing for the legend. It is well to make the drawing on a definite scale, and to record on it the proportion which the size of the picture bears to the natural size, using a fraction to express this,— e.g., Vs, V2, Vi, Vi> or whatever the scale is. INTRODUCTION 27 The drawing should always be " placed'7 carefully, so that it will not be too near either side, the top, or the bottom of the page. Space must be reserved for the legend. The drawings ought not to be crowded: one on a page is usually all there is room for, and only one side of the paper should be used.1 The gross features should first be attended to, the general direction of the lines wThich bound the structures, representing position, size, general shape, and proportions, being sketched in. These lines ought to be made as near right as possible without taking an undue amount of time. The finished drawing will be correct and satisfactory relatively to the accuracy of this pre- liminary, general sketch. The details, proceeding from larger to smaller, are to be drawn next. Usually much detail is not only unnecessary but even objectionable. The endeavor to get too much detail, and to get it without first attending to the general features, is almost the sole cause for the common remark, " I can't draw and never shall be able to!" Any one who can write can draw, and, by observing the right method and the proper sequence, can make drawings that are useful and valuable. The pencil should be medium soft; HB is the most useful grade. The lines should be drawn on, not into, the paper, and this requires lightness of touch. The pencil point is to be kept long and sharp,2 so that it will mark readily and make a fine line that can be seen while it is being made. The strength (that is, width and blackness) of the various lines in the finished drawing should be proportionate to the relative importance of the struct- ures which they represent. The term " relative importance" has reference here not to anatomical or physiological value, but to interest in the picture : the 'things in the picture that give it a name are the things of greatest relative value in that picture. In labelling " print" the names neatly, preferably with ink. If there be difficulty in making the words straight and horizontal, light, horizontal lines may be ruled for guides ; these can after- wards be erased. No attempt should be made to form the letters exactly like printed (press) type, but a free style is to be used. The pointing lines, either dotted or unbroken, should be ruled with a sharp pencil. This differentiates them from the lines of 1 The right side of the drawing-paper should always be used. The wrong side (when only one side is for use) is dimpled so as to look as if impressed with cotton or linen. 2 A piece of sand-paper glued to a strip of wood is handy for this. 28 INTRODUCTION the drawing. It is sometimes well to mark the exact termination of the line by a small cross. The name of the drawing in larger letters may be placed at the head or at the foot of the page. The view-point, scale, and date should also be given. Each sheet of the drawings should be initialed for identification, the initials being placed where they cannot be clipped off. Actual representation of an object is limited to the two dimen- sions of a plane. The third dimension of solid bodies is ex- pressed by perspective, which is made up of several factors, chiefly (a) binocular vision, (b) aerial perspective, (c) foreshort- ening, (d) sequence of objects, (e) chiaroscuro, or relation of light and shade. The part played by binocular vision is of use only in stereo- scopic pictures. Laboratory drawing is limited almost wholly to representation of things as seen by one eye. Foreshortening refers to apparent size and shape of objects (or surfaces) as dependent on position and distance. Ordinarily we do not take cognizance of it at all, or only partially. It may be made evident in several ways, — as, by inverting the head and looking at things upside down; by looking at them in a mirror and regarding the images as situated on its surface ; or by inter- posing a transparent plane object (wire netting or glass — e.g., window-pane) between the eye and the object, perpendicular to the line of vision, and regarding the lines as projected forward and drawn on this surface in one plane. To get a foreshortened drawing it is, then, only necessary to copy on paper the lines as thus seen; or they may be traced with crayon or India ink on the mirror, net, or glass itself. Objects that are partly hidden by nearer objects are thereby shown to be more distant than the latter. Aerial perspective, affecting color, distinctness of detail, etc., is of importance only when the distances are considerable, as in landscape, and need not be discussed here. The shading is self-evident. It is due to the amount of light reflected to the eye from the various surfaces, or areas of a sur- face, which have different directions, and therefore receive and reflect different amounts of light. For the purposes of drawing, the object may be regarded, and represented, as illuminated by light coming from a source above to the left. This simplifies shading and gives it a constant significance in expressing direc- tion of surfaces. (It is to be noted that shading can also be used, as in black and white pictures, to represent color-value or rela- INTRODUCTION 29 tive brightness of objects of different colors.) All surfaces so directed as to receive and reflect most of this light to the ob- server's eye will be brightest (unshaded, or having " high lights77); those directed away from the light will be darkest (shaded, or in shadow) ; while surfaces having an intermediate direction will be shaded less or more according as they approach one or other of the above extremes. A plane surface will have uniform light or shading. Rounded surfaces will have graduated shading ; areas separated by sharp edges will have abrupt differences of shading, the contrast being greater the smaller the angle between the adjacent areas, or, in other words, the greater the difference in their direction. In rounded objects the highest light and the deepest shade are sit- uated close to, but not at, the edge of the outline. All the shading should be kept right in relation to the deepest shadow. The student should examine book-illustrations and observe how shading is represented, (a) Some degree of depth may be given in a mere outline drawing by making the lines on the lower right side of the objects heaviest, (b) Plain parallel lines are used for shading in " line" drawings. The depth of shading is varied by the heaviness of the lines, their distance apart, and by " cross-hatching" or putting additional sets of shade-lines over the first at very acute angles of crossing.1 (c) The pencil may be held obliquely and rubbed most on the parts to be shaded, giving a photographic effect, (d) Some of the lead of the pencil may be scraped off with a knife and applied to the drawing-paper by means of a paper stump, giving a means of rapid working, but one that is apt to give a smudgy effect, (e) Wash-drawings are shaded either by repeating the wash or by using a stronger wash on the shaded parts. (/) A softer pencil may be used for the deeper shading. Finally, it is well to " pick out" the high lights with a soft eraser, (g) Dots may be used instead of lines, as in stippled drawings, Ross-board drawings, and half-tone illus- trations. Colors may be utilized to differentiate structures, — e.g., red for arteries, blue for veins, brown for muscles, green or orange (or plain black) for nerves. Good crayons are useful here. Big- gins's inks of various colors may be used in pen work. Washes are very effective also. As a rule, all color should be used very sparingly, and so should shading. 1 Sometimes the shading lines are curved in conformity to curvatures of the surfaces depicted, as may be seen in old wood-prints, steel engravings, and mechanical drawings. 30 INTRODUCTION To prevent smudging of soft pencil work, the drawings may be " fixed" by spraying them lightly with a fixative, such as bleached shellac dissolved in absolute alcohol or the regular solution that may be obtained, together with a spray-pipe, from dealers in artists' supplies. BOOKS. In addition to this Laboratory Manual, the student of gross human anatomy is advised to provide himself with certain neces- sary text-books, concerning which he should consult his in- structor. In the University of Chicago the following are recom- mended : (1) A good atlas of the human body, preferably W. Spalteholz's " Hand Atlas of Human Anatomy" (Barker's translation), or C. Toldt's " Anatomischer Atlas." (2) A good systematic text-book of human anatomy, preferably (at time of writing) the " Systematic Text-Book of Human Anatomy" edited by D. J. Cunningham or Quain's " Elements of Anatomy" edited by Schafer and Thane. (3) A text-book of embryology, preferably (at present) McMurrich's "Human Embryology" or C. S. Minot's "Embryology" or (if the student can read German) J. Kollmann's " Lehrbuch der Entwickelungsgeschichte des Menschen." (4) A text-book on neurology, preferably Barker's "The Nervous Sys- tem and its Constituent Neurones," or Van Gehuchten's text-book if a French, or Obersteiner's or Edinger's if a German, author be desired. LIBKARY. Students beginning to study medicine often have difficulty in learning how to use libraries and how to find the bibliography of a subject in which they are interested. Each student should at the earliest opportunity request an instructor or a librarian to teach him how to use the " Index-Catalogue of the Surgeon- General's Library77 and the " Index Medicus," the keys to medi- cal literature. For convenience, a list of some of the more important reference-books and journals to be consulted in con- nection with anatomical studies is here inserted. The student will find these books and journals in the college library. If any of them are lacking, he should use his influence to have them added to the library collection as soon as possible. The list is by no means exhaustive, but includes some of the books and journals likely to be frequently consulted; it does not consider the literature of microscopic anatomy and histology. INTRODUCTION 31 General Works on Human Anatomy. Allen, H. A System of Human Anatomy. Including its Medical and Surgical Relations. 4to. Philadelphia, 1882. v. Bardeleben, C. Handbuch der Anatomic des Menschen. 8 vols. Jena, 1902. Gegenbaur, C. Lehrbuch der Anatomic des Menschen. 7 Aufl. 2 vols. 8vo. Leipzig, 1898. Gerrish, F. H. A Text-book of Anatomy by American Authors. 2d ed. Phila. and New York, 1902. Gray, H. Anatomy, Descriptive and Surgical. Ed. by T. Pickering Pick and R. Howden. Phila. and New York, 1901. Huntington, G. The Anatomy of the Human Peritoneum and Abdominal Cavity, considered from the Stand-point of Development and Comparative Anatomy. New York, 1903. Krause, W. Handbuch der Anatomic des Menschen, mit einem Synonymen- register. Auf Grundlage der neuen Baseler anatomischer Nomenklatur unter Mitwirkung von W. His und W. Waldeyer und unter Verweisung auf den Handatlas von W. Spalteholz bearbeitet. Leipzig, 1898. von Langer, C. Lehrbuch der systematischen und topographischen Anatomic. 5 Aufl. 8vo. Wien und Leipzig, 1893. Morris, H. Human Anatomy. A Complete Systematic Treatise by Various Authors, including a Special Section on Surgical and Topographical Anat- omy. Last edition. Philadelphia. Poirier, P., et A. Charpy. Traite d' Anatomic humaine. 5 vols. Paris, 1901. Quain, J. Elements of Anatomy. Ed. by Schafer and Thane. 10th ed. 3 vols. London and New York, 1892. Rauber, A. Lehrbuch der Anatomic des Menschen. Leipzig. Sappey (M. — P. — C.). Traite d' Anatomic descriptive. 3 vols. 12mo. Paris, 1850-1864. Testut, L. Traite d'Anatomie humaine. 2 vols. royal 8vo. Paris, 1889-1891. Anatomical Atlases. Anatomischer Atlas f iir Studirende und Aerzte unter Mitwirkung von Professor Dr. Alois Dalla Rosa. Hrsg. von Carl Toldt. Wien und Leipzig, 2 Aufl., 1900. Broesike, G. Anatomischer Atlas des gesamten menschlichen Korpers. Berlin, 1899. Sobotta, J. Atlas der Anatomic des menschlichen Korpers. Miinchen, 1904. Spalteholz, W. Hand Atlas of Human Anatomy. Translated by L. F. Barker from the 3d German edition. 3 vols. Leipzig, 1901-1903. [The descriptive text accompanying the plates of this atlas is a model of conciseness; some students prefer it to that of the larger systematic text-books.] Manuals of Dissection. v. Bischoff, Th. L. W. Fiihrer bei den Prapaririibungen bearbeitet von Dr. N. Ruedinger. Miinchen, 1889. Braune, W., and His, W. Manuel de Dissection. Trad, par le Dr. G. Foettinger. Svo. Bruxelles, 1887. Campbell, W. A. Outlines of Anatomy for Students. A Guide to Dissection, based on Morris's Text-book of Anatomy. Svo. Philadelphia, 1895. 32 INTRODUCTION Cooke, T., and Cooke, F. G. H. Tablets of Anatomy, llth ed. 3 vols. London, 1898. Cunningham, D. J. Manual of Practical Anatomy. Philadelphia and London, 1903. Eckley, W. T., and Eckley, C. D. A Manual of Dissection and Practical Anat- omy. Philadelphia, 1903. Heath, C. Practical Anatomy; a Manual of Dissections. 8th ed. 12mo. Ed. by W. Anderson. Philadelphia, 1893. Holden's Anatomy. A Manual of Dissection of the Human Body. 7th ed., re- vised by A. Hewson. 2 vols. Philadelphia, 1901. Ruge, G. Anleitungen zu den Prapaririibungen an der menschlichen Leiche (1 und 2 Theile). 8vo. Leipzig, 1888. Anatomy of the Nervous System. Barker, L. F. The Nervous System and its Constituent Neurones. New York, 1900. Bruce, A. A Topographical Atlas of the Human Spinal Cord. Edinburgh, 1901. Dejerine, J. Anatomic des centres nerveux. 2 vols. 1895. Donaldson, H. H. The Growth of the Brain. New York and London, 1895. Edinger, L. Anatomy of Central Nervous System of Man and of Vertebrates in General. Transl. by W. S. Hall. Philadelphia, 1899. Flatau, E. Atlas des menschlichen Gehirns und Faserverlauf . Berlin, 1899. v. Gehuchten, A. Anatomic du Systeme nerveux de 1'homme. 3d ed. Louvain, 1900. Gordinier, H. C. The Gross and Minute Anatomy of the Central Nervous System. 1900. Hardesty, I. Neurological Technique. Chicago, 1902. v. Koelliker, A. Handbuch der Gewebelehre. Bd. ii. Leipzig, 1896. v. Lenhossek, M. Der feinere Bau des Nervensystems im Lichte neure Forsch- ungen. Berlin, 1895. Obersteiner, H. The Anatomy of the Central Nervous Organs in Health and in Disease. Transl. by A. Hill. London, 1900. Sabin, F. R. An Atlas of the Medulla and Midbrain: A Laboratory Manual. Edited by H. McE. Knower. Baltimore, 1901. Whitaker, J. R. Anatomy of the Brain and Spinal Cord. London, 1899. Whitehead. Anatomy of the Brain. Detroit, 1900. Ziehen, Th. Nervensystem, in Bardeleben's Handbuch der Anatomic des Men- schen. Surgical and Topographical Anatomy. v. Bardeleben, K., H. Hackel, und F. Frohse. Atlas der topographischen Anato- mic des Menschen. 2 Aufl. Jena, 1901. Deaver, J. B. Surgical Anatomy. 3 vols. Philadelphia, 1900-1903. Joessel, G. Lehrbuch der topographisch-chirurgischen Anatomic mit Einschluss der Operationsiibungen an der Leiche. Bearbeitet von W. Waldeyer. Bonn, 1898. McClellan. Regional Anatomy. Philadelphia, 189 — . Merkel, F. Handbuch der topographischen Anatomic. Braunschweig, 1898. Riidinger, N. Cursus der topographischen Anatomic. 4 Aufl. Miinchen, 1899. Treves, F. Surgical Applied Anatomy. 4th ed. London, 1889. Zuckerkandl, G. Atlas der topographischen Anatomic des Menschen. Wien, 1900. INTRODUCTION 33 Anatomy for Artists. Fritsch, G. Die Gestalt des Menschen. Stuttgart, 1899. Pfeiffer, L. Handbuch der angewandten Anatomic. Leipzig, 1899. Stratz, C. H. Die Schonheit des weiblichen Korpers. Stuttgart, 1899. Thompson, A. Handbook of Anatomy for Art Students. 2d ed. London, 1899. Comparative Anatomy of Vertebrates. Claus, C. Text-book of Zoology. 2d Eng. ed. London, 1890. Gegenbaur, C. Vergleichende Anatomic der Wirbelthiere mit Beriicksichtigung der Wirbellosen. Leipzig, 1898-1900. Jayne, H. Mammalian Anatomy as a Preparation for Human and Comparative Anatomy. Philadelphia, 1898. Parker, T. J., and W. A. Haswell. A Text-book of Zoology. 2 vols. London and New York, 1897. Wiedersheim, R. Grundriss der vergleichende Anatomic der Wirbelthiere. Jena, 1898. The Cambridge Natural History. 1895 on. Embryology. Balfour, F. M. A Treatise on Comparative Embryology. 2 vols. 1880-1881. Duval, M. Atlas d'Embryologie. Paris. Heisler, J. C. A Text-book of Embryology. Philadelphia, 1899. Hertwig, 0. Lehrbuch der Embryologie. His, W. Anatomie menschlichen Embryonen. Leipzig. Kollmann, J. Lehrbuch der Entwickelungsgeschichte des Menschen. McMurrich. Text-book of Human Embryology. Philadelphia, 1903. Minot, C. S. Human Embryology. New York. Anomalies. Le Double, A. Traite de variations du systeme musculaire de 1'homme et de leur signification au point de vue de Panthropologie zoologique. Tomes i., ii. Paris, 1897. Le Double, A. F. Traite des variations des os du crane de Phomme. Paris, 1903. Testut, Leo. Les anomalies musculaires chez Phomme expliqnees par Panatomie comparee, leur importance en anthropologie. Paris, 1884. Current Literature of Gross Anatomy. American Journal of Anatomy. Baltimore. Anatomischer Anzeiger. Jena. Archiv fur Anatomie und Entwickelungsgeschichte. Leipzig. Internationale Monatschrift fur Anatomie und Physiologic. Jahresberichte liber die Fortschritte der Anatomie und Entwickelungsgeschichte. Hrsg. von G. Schwalbe. Jena. Journal of Anatomy and Physiology. London. Merkel-Bonnet's Ergebnisse der Anatomie und Entwickelungsgeschichte. Wies- baden. Zeitschrift fiir Morphologic und Anthropologie. Hrsg. von Prof. Dr. Schwalbe. Stuttgart. 3 34 INTRODUCTION DIVISION OF THE CADAVER INTO PAETS. The number of men assigned to a given cadaver and the part that each will dissect will vary in different laboratories, partly according to the supply of material, partly according to the par- ticular plan favored by the instructor. Very satisfactory methods of division have been agreed upon, among others the following : A. For ten students to a cadaver, five on each side. 1. Arm and wall of thorax (extremitas superior). 2. Lower extremity (extremitas inferior). 3. Head, neck, and dorsum of trunk (caput, collum, et dorsum trunci). 4. Thorax. 5. Abdomen and pelvis (abdomen et pelvis). B. For six students to a cadaver, three on each side. 1. Arm and wall of thorax (extremitas superior). 2. Lower extremity, abdomen, and pelvis (extremitas inferior, ab- domen, et pelvis). 3. Head, neck, and upper part of trunk (caput, collum, dorsum trunci, et thorax). C. For four students to a cadaver, two on each side. 1. Upper half of body (caput, collum, dorsum trunci, thorax, et extremitas superior). 2. Lower half of body (extremitas inferior, abdomen, et pelvis). ANATOMICAL TEEMS INDICATING THE POSITION AND DIRECTION OF PAETS OF THE BODY. In descriptive anatomy certain technical terms, derived chiefly from the Latin and Greek, are necessary for the desig- nation of parts of the body and for specifying exactly their spatial relations. In descriptions the human body is usually thought of as standing upright, with the arms hanging at the sides, — i.e., alive ; the older anatomists always represented the volar surface of the forearm and the palm as looking forward, but at present no definite position in space is ascribed to the forearm. The body, so nearly symmetrical, is thought of as being halve'd by a per- pendicular plane, the so-called median (medianus) plane, into a right and a left half. The direction towards this median plane is designated as medial (medialis) ; that away from it, lateral (lateralis). By a vertical direction (verticalis) is meant one corresponding to the long axis of the median plane; a plane or line at right angles to the median plane, if it be parallel to the INTRODUCTION 35 surface of the earth, is spoken of as being horizontal (horizon- tails) ; if it merely run across the body or one of its parts at right angles to the axis of the body, it is said to be transversal (transver salts). The term transverse (transversus) means across the long axis of the organ concerned. Lines or planes which run parallel to the median plane are called sagittal (sagit- talis) ; those parallel to the surface of the forehead, frontal (front alls}. The terms inner (internus) and outer (externus) have been very loosely used in English text-books, often being employed in the sense of medial and lateral, as well as indicating the direc- tion in relation to the interior of organs, cavities of the body, or regions of the body; in the nomenclature used in this book the terms are restricted exclusively to the latter meaning. In de- scribing the dimensions of organs length or longitudinal direc- tion (longitudinalis) , breadth or transverse direction (trans- versus), and thickness are the terms employed to indicate the largest, middle, and smallest dimensions. Particular attention is called to the distinction between transversus and transver sails, the latter being reserved for a direction transverse to that of the median plane. The terms upper (superior] and lower (inferior] refer to the directions towards the vertex and towards the sole of the foot respectively, while the terms superficial (superficialis) and deep (profundus) indicate a position of less or greater separa- tion from the external surface of a part or organ. The term middle (medius) is used to indicate a position between superior and inferior or between externus and internus, but, since medius is easily confused by the beginning student with medialis, espe- cially when abbreviated, the term intermediate (intermedium) is employed to indicate a position midway between lateralis and medialis. In order to have terms, independent of the position of the body in space, for the directions towards the head-end or the tail-end of the body, the designations cranial (cranialis) and caudal (caudalis) have been introduced. In the head itself the continuance of the cranial direction can no longer very satis- factorily be designated as cranial ; accordingly, this direction as far as the mouth or the nose is spoken of as rostral (rostmlis). When the body is in the upright position, the direction towards the front is spoken of as anterior, that towards the back as posterior; the same directions in the body thought of as inde- pendent of its position in space, are spoken of as ventral (ven- 36 INTRODUCTION trails) and dorsal (dorsalis). The adjectives right (dexter) and left (sinister) have their ordinary meaning. Besides these general terms for the body as a whole, certain special terms for the extremities (termini ad extremitates spec- t antes) are found convenient. In the extremities especially it is desirable to have designations independent of the position in space. The direction towards the trunk is, therefore, spoken of as proximal (proximalis) ; that away from the trunk, as distal (distalis). In the forearm and hand the direction towards the thumb side is spoken of as radial (radialis) ; that towards the little-finger side, as ulnar (ulnaris) ; similarly, in the leg the direction towards the great-toe side is spoken of as tibial (tibi- alis) and that towards the little-toe side as fibular (fibularis). Furthermore, in both upper and lower extremities, for the ex- tensor surfaces the expression dorsal (dorsalis) is used; while for the flexor surfaces the term used in the forearm and hand is volar (volaris) ; that in the foot, plantar (plant aris). GENERAL ANATOMICAL TEEMS (TERMINI GEN ER ALES). A list of certain general terms, with the English synonyms, employed in gross anatomy is here included. It is not intended that the student should begin his work by memorizing these words. On the contrary, he will learn them best by adding them gradually to his vocabulary as the dissection proceeds. Accessorius (accessory). Acinus (berry). Aditus (entrance). Ala (wing) (contraction of axilla}. Alveolus (little hollow). Ampulla (flask). Angulus (angle). Ansa (handle or loop). Antrum (cave). Apertura (opening). Apex (tip). Appendix (appendage). Arcus (arch). Area (space). Axilla (wing). Basis (base). Brachium (arm). Canaliculus (small channel). Canalis (canal). Capitulum (little head). Capsula (capsule). Caput (head). Cartilago (cartilage). Caruncula (small piece of flesh). Cauda (tail). Caverna (cavern). Cavum (hole or cavity). Cellula (little chamber or cell). Circulus (circle). Cisterna (cistern). Collum (neck). Columna (column or pillar). Commissura (connection or commis- sure). Cornu (horn). Corona (wreath, garland, or crown). Corpus (body). Corpusculum (little body or cor- puscle). Crista (crest). INTRODUCTION 37 Cms (leg or limb). Decussatio (decussation or crossing). Dorsum (back). Ductulus (little duct). Ductus (duct). Eminentia (eminence or protuber- ance). Endothelium (endothelium). Epithelium ( epithelium ) . Extremitas ( extremity ) . Facies (face or surface). Fascia (bandage or band). Fasciculus (a little bundle or packet). Fibra (fibre or filament). Fibrocartilago ( fibrocartilage ) . Filum (thread). Fissura (fissure or cleft). Flexura (bending). Folium (leaf). Folliculus (little sac or bag). Foramen (hole, aperture, opening). Formatio (formation). Fornix (arch or vault). Fossa (ditch or trench). Fossula (little fossa). Fovea (pit). Foveola (little pit). Frenulum (cord or rein). Fundus (bottom). Funiculus (thin rope, cord, or string). Geniculum (little knee or knot). Genu (knee). Glandula (gland). Glomerulus (little skein). Glomus (skein). Hilus (hilus). Humor (liquid or fluid). Junctura ( j oint ) . Impressio (impression). Incisura (incision or notch). Inf undibulum ( funnel ) . Intestinum (intestine or inward). Isthmus (isthmus). Labinm (lip). Lacuna (gap, defect). Lamina (plate or layer). Latus (broad; flank). Ligamentum (ligament). Limbus (border or fringe). Limen (threshold or boundary). Linea (line). Liquor (fluid or liquid). Lobulus (a little lobe). Lobus (lobe). Macula (spot). Margo (margin). Massa (mass). Meatus (way or passage). Medulla (marrow). Membrana ( membrane ) . Membrum (limb or member). Mucus (mucus). Musculus (muscle). Nervus (nerve). Nodulus (nodule). Nucleus (nucleus or kernel). Organon (organ). Orificium (orifice). Os, oris (mouth). Os, ossis (bone). Ostium (entrance). Papilla (papilla or nipple). P arenchy ma ( p arenchy ma ) . Paries (wall). Perichondrium ( perichondrium ) . Periosteum ( periosteum ) . Plexus (plexus). Plica (fold). Polus (pole). Processus (process). Prominentia (prominence or projec- tion). Punctum (point or small puncture). Radix (root). Ramulus (little branch or twig). Ramus (branch). Raphe (raphe or seam). Recessus (recess). Regio (region or territory). Rete (net or net-work). Rim a (slit or fissure). Rudimentum ( rudiment ) . Septulum (little septum). Septum (partition). Sinus (sinus). Spatium (space). Spina (spine or thorn). Stratum (layer or covering). Stria (furrow, stripe, or ridge). Stroma (stroma, orbed). Substantia (substance). Succus (juice). 38 INTRODUCTION Sulcus (sulcus or furrow). Tsenia (ribbon; tapeworn). Tegmen (a cover). Tela (web). Tela conjunctiva (connecting web). Tela elastica (elastic web). Torus (round swelling or protuber- ance). Trabecula (little beam). Tractus (tract). Trigonum (trigone or triangle). Trochlea (pulley). Truncus (trunk). Tuber (swelling or hump). Tuberculum (tubercle). Tubulus (tubule or little tube). Tunica (coat or covering). Tunica propria (proper coat). Umbo (boss or prominence). Uvula (little cluster or bunch). Vagina (sheath). Vallecula (crevice). Vallum (wall or fortification). Valvula (valve). Vas (vessel). Velum (sail, covering, or curtain). Vertex (crown of head). Vesica (bladder). Vesicula (vesicle or little bladder). Vestibulum (vestibule or antechamber), Villus (shaggy hair). Viscera (entrails, viscera). Viscus (organ, internal organ). Vortex (whirlpool). Zona (girdle or zone). Part I DISSECTION OF THE UPPER EXTREMITY LABORATORY MANUAL OF HUMAN ANATOMY UPPER EXTREMITY MAKE four drawings : (a) anterior view of the upper extrem- ity and the wall of the thorax, (b) posterior view of the same, (c) lateral view of the upper extremity, (d) medial view of the same. In the drawings show that the upper extremity (extremitas superior) is attached to the chest (thorax) in the clavicular and scapular regions. Note the prominence of the shoulder (axilla) 1 and the projection in its upper lateral part (acromion). Con- tinuous with the shoulder is the rounded upper arm (brachium) ; beneath it, between the brachium and the thorax, is the axillary fossa (fossa axillaris). Draw in its anterior and posterior bounding folds (plica axillaris anterior, plica axillaris poste- rior). Show how the forearm (antibrachium) joins the brachium at the elbow (cubitus) ; illustrate the change in size and shape of the antibrachium distalward. In the drawings of the brach- ium label the anterior surface (fades anterior), posterior sur- face (fades posterior), lateral surface (fades lateralis), and medial surface (fades medialis), also the sulcus bidpitalis lat- er alls and the sulcus bidpitalis medialis; in the forearm distin- guish the radial side or border (mar go radialis), the ulnar side (mar go ulnaris), the dorsal surface (fades dorsalis), and the volar surface (fades volaris). Note how the hand (manus) is attached to the antibrachium by the narrower wrist (carpus). Distinguish the proximal por- tion of the hand (metacarpus) from the subdivided distal por- tion, the fingers (digiti manus). Number the digits from the thumb side. The thumb is the first (digitus L, or pollex), the index-finger is the second (digitus II., or index), the middle 1 This is the proper usage of " axilla." In English texts it is often used as synonymous with " fossa axillaris." 41 42 LABORATORY MANUAL OF HUMAN ANATOMY finger is the third (digitus III., or digitus medius), the ring- finger is fourth (digitus IV., or digitus annularis), and the little finger is fifth (digitus V., or digitus minimus). Notice the rela- tive lengths of the digits, especially the relation of the length of the index-finger to that of the ring-finger. Is this constant? In the hand make careful drawings of the " back of the hand" (dorsum manus) and of the flattened " hollow of the hand" (vola manus, s. palma), also of the " thumb side" of the hand (mar go radialis) and of the " little finger side" (mar go ulnaris). In each digit distinguish the facies dorsalis from the facies volaris .and the margo radialis from the margo ulnaris. In the upper extremity what is meant by the " proximal direction" or a " proximal part"? what by the " distal direction" or a " distal part"! In the drawings of the upper part of the trunk or chest (thorax) show its relation to the belly (abdomen). In the back (dorsum) look at and feel the spines of the vertebral column (columna vertebralis). Number these in your drawing and pay especial attention to the exact level of each and the relations of other parts (e.g., scapula) to their levels. Designate the spine of vertebra C. VII. separating the neck from the back. Illustrate the position of the projections corresponding to the ribs (costae) and number them. Note especially the rib-levels of the papilla mammae and of various portions of the scapula when the arm is in different positions. Draw the breast and show the depression between the two breasts, the so-called bosom (sinus). Below the bosom, just under the sternum, indicate the flattened so-called " heart fossa" (scrobiculus cordis). Show the limits of the areola mammae about the nipple, and, if Montgomery's glands (glandulae areolares [Montgomerii]) are visible, picture them. Draw in certain lines useful in topographical anatomy : (1) Anterior median line (linea mediana anterior). (2) Posterior median line (linea mediana posterior). (3) Sternal line (linea sternalis), along the lateral margin of the sternum. (4) Mammillary line (linea mammillaris), falling perpendicularly through the nipple. (5) Parasternal line (linea par ast emails) , midway between sternal and mammillary lines. (6) Costo-articular line (linea costo-articularis) , from the sternoclavicu- lar articulation to the tip of the eleventh rib. (7) Axillary line (linea axillaris), perpendicularly from the centre of the fossa axillaris. (8) Scapular line (linea scapularis), perpendicularly through the lower angle of the scapula. Vrigonum ~ \ deltoideopectordle [ ao,w.m-, i a^aoaom- VL-— ^ », i \ inati, I / inans I \? | | M ^G'Ml! /-J-l. _Vi / /k n v \v«.jN*«iix / r ta-. /-— V" i IT /- SiA. H2=K /-4 -f-TW I VA"-""""^ / il" -/ iHnf^ -f-li -R.brachii laterali* --B.mbiti la!erali» R.antil>mcKii.aor*(iHt R.nnMiiguinalis R.trocliaiiterica, The regions of the anterior surface of the body. ( After His, Anatomische Noinenclatur, Leipzig, 3895, Plate I.) FIG. 2. R.aMominalis lateralis. R.otecmni- B.cubili paste, wr Fossa retromnllfola R.rett oinalleolaris lateralis— The regions of the posterior surface of the body. (After His, Anatomische Nomenclatur, Leipzig, 1895, Plate II. ) DISSECTION OF THE UPPER EXTREMITY 45 Make four additional outline sketches and insert the " re- gions " of the upper extremity and thoracic wall, having first marked them out accurately with the end of the probe on the body. Use Figs. 1 and 2 as a guide. Ask yourself the reason for the name of each region. EEGIONS OF THE BACK (REGION ES DORSI). Surface Anatomy. In the median region of the back (regio mediana dor si) pal- pate the spinous processes (processus spinosi) of the vertebrae. Are they all in one plane ? Find the spine of the seventh cervical vertebra (vertebra prominens). Are any other spines especially noticeable? Enumerate the spines consecutively. Is there any marked kyphosis, lordosis, or scoliosis present?1 Palpate the scapula and ascertain its general outline. Move the arm in various directions and note accompanying changes in position of scapula. With the arm of the cadaver by the side, establish the spinal level and the rib-level of the angulus medialis and of the angulus inferior of the scapula. Run the finger along the spina scapulae and the acromion and note that both are subcu- taneous. Establish exactly the bony point corresponding to the junction of the lower border of the spina scapulae with the lat- eral margin of the acromion. ( Surgeons measure the arm from this point, the tape being carried down to the epicondylus later- alis of the humerus.) Superficial Structures. Make skin incisions (1) along the linea mediana posterior from the vertebra prominens to the tip of the coccyx, (2) from the tip of the coccyx to the posterior superior iliac spine, then along the crista iliaca to near the anterior superior iliac spine, (3) from the vertebra prominens to the medial edge of the acromion, and (4) from the processus spinosus vertebrae Jumbal is I. to the lateral margin of the acromion. Reflect the two triangular flaps of skin, taking none of the fat of the superficial fascia with it. Have your atlases open before you. Having ascertained the region in which tlie medial set of cuta- neous vessels and nerves is likely to be found, witli the knife make a small cut through the superficial fascia down to the deep 1 When a word is met with in this manual (or in any text-book) which is new to the student, he should look up its meaning at once in a good medical dictionary. 46 LABORATORY MANUAL OF HUMAN ANATOMY FIG. 3. fascia. With the special heavy probe recommended, separate an area of the superficial fascia until you encounter the trunk of a blood-vessel or a nerve coming through the deep fascia from below to enter the superficial fascia. It is common to find a nerve, an artery, and a vein together. Carefully separate the structure or structures found from the superficial fascia, tracing the blood-vessel or nerve as far as possible and cleaning it thor- oughly. In this way, isolate all the superficial blood-vessels and nerves in the medial and lateral areas in which they occur. The nerves and blood-vessels will be found emerging through the deep fascia. Their course and ramifications in the superficial fascia are to be traced out with- out removing the fat or disturb- ing the relations of the struct- ures any more than is necessary in exposing them. It should be borne in mind that it is only the natural relations that are of im- portance, and not the artificial relations due to dissection. Hence each structure should be studied as it is worked out, in- stead of its study being deferred until after it is isolated and cleaned. When the cutaneous nerves and vessels and superfi- cial glands have been thus ex- posed, a drawing of these should be made ; or the drawing may be made concurrently with the dissection, being then an aid to the determination of the exact relations. The deep fascia should be cleaned (by careful removal of the superficial fascia by blunt dissection) and its extent, nature, and attachments studied. The fasciae should then be removed piece- meal. In cleaning the surface of the muscles, place the body in such a position that the muscle-fibres will be rendered tense and carry the knife in the direction which permits removal of the fascia with the least disturbance of the underlying muscle. Care Skin incisions on the posterior surfaces of the body. DISSECTION OF THE UPPER EXTREMITY 47 FIG. 4. M. scmiitpinaliti capitis (turned back) Jf. rt'ctuft capifin ]ni. lumbalis III. Fascia transversalis M. latissimus dorsi Upper surface of the vertebra lumbalis IV. M. transversus abdominis M . obliquus interims abdominis i M. obliquus externus abdominis Fascia superficial^ Integumentum commune M. rectus abdominis Linea alba : : Umbilicus Lamina anterior Lamina posterior Vagina M. recti abdominis The muscles and fasciae in a transverse section of the right half of the wall of the trunk. (After Toldt, Anat. Atlas, Wien, 1900, 2 AufL, p. 281, Fig. 520. ) (a) External ramus of accessory nerve (ramus externus N. accessorii). (b) Muscular rami from cervical nerves (rami muscular es Nn. cervica- lium). DISSECTION OF THE UPPER EXTREMITY 51 Broad Muscles of the Back (Second Layer). Make the rhomboid muscles tense and clean their surfaces carefully. Find the trunk of the dorsal nerve of the scapula (A7, dor sails scapulae] (O. T.. nerve to the rhomboids) and the descending ramus of the transverse artery of the neck (A. trans- versa colli) in the interval between the M. levator scapulae and the M. rhomboideus minor. (a) Greater rhomboid muscle (M. rhomboideus major). (b) Lesser rhomboid muscle (M. rhomboideus minor). (c) Levator muscle of scapula (M. levator scapulae) (0. T. levator anguli scapulae). Establish the form, position, origin, insertion, action, and innervation of each. Find the two rami of the cervical nerve on the surface of the M. levator scapulae and then cut the muscle in two in the middle. Eeflect the lower portion lateralward. Cut through the attachments of the Mm. rhomboidei near the median plane and reflect the muscles lateralward. Dissect out care- fully- (a) Dorsal nerve of scapula (N. dorsalis scapulae). (b) Descending ramus of transverse artery of neck (ramus descendens A. transversae colli) (0. T. posterior scapular artery). Near the superior margin of the scapula expose the inferior belly of the omohyoid muscle (venter inferior M. omoliyoidei}. Define its exact attachment to the scapula. Note the relations of the A. transversa scapulae (0. T. suprascapular artery) and of the N. suprascapularis to the Lig. transversum scapulae superius. The dissector of the arm may next assist the dissector of the head in making out the muscles of the back. Study the form, position, origin, insertion, action, and innervation of each. ANTERIOR THORACIC REGION AND AXILLARY FOSSA. Surface Anatomy. Examine— (a) Outline of clavicle. (aa) Shaft of clavicle. (ab) Sternal extremity (extremitas sternalis). (ac) Acromial extremity (extremitas acromialis). 52 LABORATORY MANUAL OF HUMAN ANATOMY Compare the distance between the acromion and the ster- nal extremity of the clavicle on the two sides. Why would such a comparison be of importance in surgical diagnosis? (b) Outline of sternum. (ba) Manubrium sterni. Jugular notch (incisura jugularis) (0. T. suprasternal notch). (bb) Corpus sterni (0. T. gladiolus). Angle of sternum (angulus sterni) (0. T. angulus Ludovici, angle of Louis), an important landmark in counting ribs and intercostal spaces. (be) Processus xiphoideus (0. T. ensiform process). (c) Costal arches I -XII. (ca) Ribs (costae I.-XIL). (cb) Costal cartilages (cartilagines costales). Is a " rickety rosary" present ? (d) Coracoid process of scapula (processus coracoideus scapulae). Note its relation to the infraclavicular fossa (fossa infraclavicularis or Mohrenheim's fossa) and the relation of the clavicular origins of the M. pectoralis major and the M. deltoideus to the latter. (e) Breast (mamma). (ea) Papilla mammae, or nipple of the breast. Note its exact level and its distance from the anterior median line. (eb) Body of breast (corpus mammae). Note its dimensions. (ec) Areola mammae. (1) Sebaceous glands (Gl. sebaceae). (2) Areolar glands (Gl. areolares [Montgomerii]). (ed) Accessory breasts (mammae accessoriae) . Are any present? What is the direction of the so-called " milk-line" ? Note that of the two rows of milk-glands running from the forelimb to the inguinal fold, the head- ward portions are preserved in primates, the tailward por- tions in ruminants. What are meant by the terms poly- mastism, polythelism , and atavism? (f) Boundaries of axillary fossa (upper extremity abducted). (fa) Anterior axillary fold (plica axillaris anterior). To what is it due? (fb) Posterior axillary fold (plica axillaris posterior). To what is it due? Which fold extends to the lower level ? (g) Upper extremity of humerus. Palpate, in the axillary fossa, the medial surface of the surgical neck (collum chirurgicum) and feel the head of the humerus (caput humeri) rotate when the arm is rotated. Skin and Superficial Fascia, with Vessels and Nerves. Make the following incisions in the skin (cf. Fig. 7) : (a) In the linea mediana anterior from the fossa jugularis to the tip of the processus xiphoideus. DISSECTION OF THE UPPER EXTREMITY 53 (b) From the processus xiphoideus lateralward to the back. (c) From the upper end of the first incision lateralward along the clavicle to the tip of the acromion. (d) From the processus xiphoideus obliquely upward and lateralward along the plica axillaris anterior as far as the brachium. FlG. 7. With a sharp knife dissect up the two triangular flaps marked out by the incisions mentioned. Keep the knife close to the white corium so that none of the fat of the superficial fascia is re- moved with the skin. Compare the amount of fat in the superficial fascia in your subject with that in neighboring subjects. Find the fibres of the platysma streaming down into it over the clavicle. Note that the mammary gland is situated in the superficial fascia. Cut boldly through the superficial fascia down to the deep fascia in the middle line in front, and then with the blunt probe dissect up the superficial fascia, passing gradually lateralward. Find the cutaneous blood-vessels and nerves passing into the super- ficial fascia from the depth. When the trunks of these are found, follow each carefully out as far as possible into the super- ficial fascia, cleaning it care- fully. Avoid injury to the superficial nerves which pass down over the clavicle. Keep your atlases open before you as a guide to the location of the various structures. As soon as a nerve or blood-vessel is found, identify it, getting the name from the atlas. Find a description of it in your systematic text-book of anatomy (using the index of the latter) and com- pare the actual findings in your subject with the text-book de- scription. Note especially any differences between your object- ive findings and the printed descriptions. Skin incisions on the anterior surfaces of the body 54 LABORATORY MANUAL OF HUMAN ANATOMY Ramus cutaneus anterior of the N. intercostalis I. \ Rarmis cutaneus lateralis (pecto- ralis) of the N. intercostalis VI. Rami musculares of the N. intercostalis I. Mm. intcrcostales externi M. intercostalis interims Fascia endothoracica __N. intercostalis IV. Fascia endo- thoracica N. intercostalis VII. Ramus muscularis Ramus cutaneus ante- rior (abdominalis) of the N. intercostalis IX. Ramus cutaneus later- alis (ramus anterior) of the N. intercosta- lis XII. Ramus cutaneus anterior of the N. intercosta- lis XII. Ramus cutaneus anterior of the N.iliohypogas- tricus N. ilioinguinal . oil/quits internus abdomini* ._. M. transvcrsus N. intercostalis XII. Rami musculares Ramus muscu- laris of the N. ilioinguinalis ...N. ilioin- guinalis ,,N. spermaticus externus The cutaneous nerves of the anterior side of the trunk. (After Toldt, Anat. Atlas, Wien, 1903, 3 Aufl., p. 814, Fig. 1246. ) DISSECTION OF THE UPPER EXTREMITY 55 Study the following: Superficial Nerves. (Fig. 8.) (a) Supraclavicular nerves (Nn. supraclaviculares) (0. T. descending cutaneous nerves). (aa) Anterior (Nn. supraclaviculares anteriores) (0. T. supra- sternal branches). (ab) Middle (Nn. supraclaviculares medii) (0. T. supraclavicu- lar branches). (ac) Posterior (Nn. supraclaviculares posteriores) (0. T. supra- acromial branches). What are their relations to the platysma? (b) Anterior cutaneous rami of the intercostal nerves (rami cutanei anteriores Nn. intercostalium). (ba) Medial mammary rami (rami mam marii mediales). (c) Lateral cutaneous rami of the intercostal nerves (rami cutanei lat- erales Nn. intercostalium), dividing beneath the M. ser- ratus magnus into — (ca) Posterior rami (rami posteriores). (cb) Anterior rami (rami anteriores). Note that the latter give off the lateral mammary rami (rami mammarii laterales). Arteries. (Fig. 9.) (a) Perforating rami of internal mammary artery (rami perforantes A. mammarii internae). (aa) Mammary rami (rami mammarii). (ab) Muscular rami (rami musculares). (ac) Cutaneous rami (rami cutanei). (b) Anterior cutaneous rami of anterior rami of intercostal arteries (Rr. cutanei anteriores Er. ant. Aa. intercostalium), in fourth and sixth intercostal spaces only. (ba) Medial mammary rami (Er. mammarii mediales). (c) Lateral cutaneous rami of anterior rami of intercostal arteries (Er. cutanei laterales Er. ant. Aa. intercostalium). (ca) Posterior ramus (ramus posterior). (cb) Anterior ramus (ramus anterior). (cba) Lateral mammary' rami (Er. mammarii laterales). (d) Lateral thoracic artery (A. thoracalis lateralis). (da) External mammary rami (Er. mammarii externi). Veins. Tributaries of the axillary vein. (a) Lateral thoracic vein (V. thoracalis lateralis). (b) Thoraco-epigastric vein (V. thoraco-epigastrica) , receiving many of the Vv. cutaneae pectoris. Tributaries of the V. anonyma. (a) Tributaries of internal mammary vein. (aa) Perforating rami (rami perforantes). (ab) Intercostal veins (Vv. intercostales) (sternal extremi- ties). Tributaries of V. azygos. (a) Tributaries of intercostal veins (vertebralward). (aa) Cutaneous veins of chest (Vv. cutaneae pectoris). 56 LABORATORY MANUAL OF HUMAN ANATOMY FIG. 9. A. cervicalis superficial! A. transversa colli (arising abnormally) \ A. transversa scapulae A. subclavia dextra Ramus costalis lateralis (Var.) ^ A. mammaria interna Rami perforantes Kami cutanei M. obli- quus A. epigastrica inferior A. circumflexa ilium— profunda A. circumflexa ilium - superficialis A. lig. teretis uteri A. femoralis V. femoralis Aa. labiales anteriores/ Lymphoglandu- lae inguinal es Lymphoglandu- lae subinguinales superficiales V. saphena magna Aa. pudendae externae Arteries of the anterior body-wall. (After Toldt, Anat. Atlas, Wien, 1903, 3 AufL, p. 581, Fig. 957.) DISSECTION OF THE UPPER EXTREMITY 57 Mammary Gland (Mamma). (Fig. 10.) Compare the gland in your subject with one from a subject of the opposite sex. If the breast is well developed, dissect the gland under water and make out— (a) Lobes of breast (lobi mammae). (aa) Lobules of breast (lobuli mammae). (b) Milk-ducts (ductus lactiferi). (ba) Milk-sinuses or ampullae (sinus lactiferi). FIG. 10. Medial margin— Fascia pectoralis- - M. pectoralis major ^ Pannicidus adiposus,^ Integument um commune,- Lobuli mammae >•; Lobi mammae's;-' Papilla mammae^ Ductus lactiferi Sinus lactiferi Corpus mammae Lateral margin Horizontal cut through the female breast. (After Toldt, Anat. Atlas, Wien, 1900, 2 Aufl., p. 501, Fig. 860.) Review the blood-supply of the mamma. Study illustrations of the lymphatic channels leading from the breast to the pectoral lymph-glands (lymphoglandulae pectorales), the axillary lymph- glands (lymphoglandulae axillares), and the sternal lymph- glands (lymphoglandulae sternales). (Cf. Figs. 15, 86, and 93.) Note that where the breasts are very large the lymphatic chan- nels of one breast may communicate with those of the breast of the opposite side across the median line. Fascia Pectoralis or Deep Fascia. Note its relations above, below, medialward, and lateralward, a.nd the process from it to the fascia coracoclavicularis in the fossa infraclavicularis. 58 LABORATORY MANUAL OF HUMAN ANATOMY Greater Pectoral Muscle (M. pectoralis major). Make the muscle tense by abducting the upper extremity. Remove the fascia pectoralis from its surface and the deltoid portion of the fascia brachii from the anterior margin of the M. deltoideus. Stop at the plica axillaris anterior before reach- ing the fascia axillaris. Avoid injury to the vena cephalica and the acromial ramus of the arteria thoraco-acromialis (0. T. humeral thoracic artery). FIG. 11. Insertion of pectoralis Intermediate entopectoral slip Pectoralis minor M. pectoralis major with deficiency of sternocostal portion, and resulting production of an atypical displaced intermediate pectoral muscle (M. tensor semivaginae articulationis humero-scapularis, Gruber, M. pectoralis minimus). Adult human subject. From a fresh dissection. (After G. S. Huntington, Amer. Jour, of Anat., Baltimore, 1903, vol. ii., No. 2, Plate I., Fig. 1. ) Note in connection with the M. pectoralis major — (a) Its form. (&) Its position. DISSECTION OF THE UPPER EXTREMITY 59 (c) Its origin. (ca) Pars clavicularis. (cb) Pars sternocostalis. (cc) Pars abdominalis. (d) Its insertion. (e) Its innervation (Nn. thoracales anterior es]. (f) The bursa M. pectoralis majoris. Look up an article upon the torsion of the tendon of this muscle by Dr. Warren Lewis, in the American Journal of Anatomy. FIG. 12. ..Brachial arch Axillary arch The brachial and axillary arches. (From Poirier et Charpy, Traite d'Anat. hum., Paris, 1901, 2 ed., p. 164, Fig. 126.) Axillary Fascia (Fascia axillaris). (Figs. 12 and 13.) Carefully remove the superficial fascia over the base of the axillary fossa so as to expose the deep or axillary fascia. Note- (a) An apparent oval opening between the concave aponeurotic bands; the lower lateral concave band is the brachial arch (Armbogen of Langer) ; the upper medial concave band is the axillary arch (Achselbogen of Langer). If the dissection be made very care- fully, a delicate, much-perforated membrane can be made out, ex- tending from the brachial arch to the axillary arch, so that the bundle of vessels and nerves seen through the oval opening is not really subcutaneous. (Poirier.) Note the striking resemblance of 60 LABORATORY MANUAL OF HUMAN ANATOMY this oval opening to the fossa ovalis of the thigh, of the thin mem- brane covering it to the cribriform fascia, of the axillary arch to the cornu superius of the margo falciformis, and of the brachial arch to the cornu inferius of the margo falciformis. (6) The continuity of the fascia axillaris lateralward with the fascia brachii and with the fascia enclosing the M. latissimus dorsi and Mm. teretes major et minor; it becomes inserted into the axillary margin of the scapula. (c) The continuity of the fascia axillaris medialward, not with the fascia pectoralis, but with the fascia coracoclavicularis, which encloses the M. pectoralis minor. (Fig. 13.) The membrane extending from the axillary fascia to the lower bolder of the M. pectoralis minor was formerly called the suspensory ligament of the axilla (ligament suspenseur of Gerdy). FIG. 13. M. subscap- Bundle of nerves and vessels.... M. teres min. M. teres maj . M. lat. dorsi -.-.Clavicula M. subclav. ....Fascia coracoclav. -M. pect. min. — M. pect. maj. Axillary arch Sagittal section of the axillary fossa. (Very schematic.) (From Poirier et Charpy, Trait<§ d'Anat. hum., Paris, 1901, t. ii. p. 165, Fig. 128.) (d) The passage through the oval opening (and the cribriform fascia covering it) of the intercostobrachial nerves (Nn. intercosto- brachiales) (0. T. intercostohumeral nerves). These represent the lateral cutaneous rami of the second and third intercostal nerves (rami cutanei laterales Nn. inter cost alium II. et III.}. It is inter- esting that the vena basilica may occasionally bear the same rela- tion to the oval opening that the vena saphena magna bears to the fossa ovalis in the thigh; the usual condition, however, is for the V. basilica to pass beneath the deep fascia a little above the elbow. (e) Later in the dissection, the reflections of the axillary fascia upon the arteries and nerves going to the forearm. Structures in the Fossa Axillaris. (See Figs. 14, 15, and 16.) The fascia axillaris may now be reflected backward, care -being taken to dissect out carefully the intercostobrachial nerves. The structures in the axillary fossa are to be isolated and DISSECTION OF THE UPPER EXTREMITY 61 cleaned, the loose areolar tissue and fat in which they are era- bedded being gradually removed. Secure first the subscapular artery and the thoracodorsal nerve along the lower border of the M. subscapularis, then the lateral thoracic artery (lower border of M. pectoralis minor), next the long thoracic nerve (lying on M. serratus magnus). The various lymph-glands are FIG. 14. coracobrach. et biceps (cap. breve) T*. cephalica \ Tendon of M. lat. dorsi Tendon of caput longum \ ; / M. bicipitis M. deltoideus rM. teres major Humerus : • V. A. circ. post. N. axillaris M. teres min. M. triceps (cap. long.) Corpus scapulae Cross-section of the shoulder above the origin of the circumflex arteries, right side, segment distal to the cut. Subject fixed in formalin chromic acid. The fat over the V. and A. circumflex posterior and the N. axillaris has been removed to show the course of these structures. The N. radialis is seen medial to the N. axillaris. The N. ulnaris lies anterior to the N. radialis. The two heads of the median have just united and the N. musculocutaneus is separating off. (After Poirier et Charpy, Traite" d'Anat. hum., Paris, 1901, 2 ed., t. ii. p. 93, Fig. 87.) to be studied carefully as they are exposed and may afterwards be removed. The following structures are to be isolated and studied, some of them being best seen after the dissection of the M. pectoralis minor and the fascia coracoclavicularis. Lymphatic Glands. (Cf. Figs. 15, 86, and 93.) (a) Axillary lymph-glands (lymphoglandulae axillares}. (b) Pectoral lymph-glands (lymphoglandulae pectorales). 62 LABORATORY MANUAL OF HUMAN ANATOMY FIG. 15. Lymphoglandulae axillares— V. cephalica Lymphoglandulae cubitales superficiales Lymphatics of the arm and of the anterior and lateral sides of the thorax. (From Toldt, Anat. Atlas, Wien, 1900, 2 Aufl., p. 704, Fig. 1086.) DISSECTION OF THE UPPER EXTREMITY 63 (c) Subscapular lymph-glands (lymphoglandulae sub scapular es) . Count the number of lymph-glands found in each of these three chains. Whence do the glands of each of these three chains draw lymph? Note especially the intimate relations of the glands of the middle chain to the axillary vein. FIG. 16. Tmncus thyreocervicalis Jf. scalenus anterior '; transversa scapulae ; ; cransversa colli : : -; Ramus subclavius A. axillaris f Ramus pectoralis A. thoracoacromialis j Ramus acromialis "'• I Ramus deltoiden A . vertebralis :: A. mam TD aria interna : A. subclavia / / A. anonyma : N. medianus A. circumflexa I anterior humeri [posterior A. thoracalis lateralis The subclavian and the axillary artery and their relation to the plexus brachialis. (After Toldt, Anat. Atlas, Wien, 1900, 2 Aufl., p. G10, Fig. 986.) Arteries. (Fig. 16.) (a) Axillary artery (A. axillaris). (aa) Highest thoracic artery (A. thoracalis suprema) (0. T. superior thoracic artery). 64 LABORATORY MANUAL OF HUMAN ANATOMY (ab) Thoraco-acromial artery (A. thoraco-acromialis) (0. T. acromiothoracic or thoracic axis). (ac) Lateral thoracic artery (A. thoracalis lateralis) (0. T. long thoracic). (aca) External mammary rami (Er. mammarii externi). (ad) Subscapular artery (A. sub scapular is). (ada) Thoracodorsal artery (A. thoracodorsalis) . (adb) Circumflex artery of scapula (A. circumflexa scapulae) (0. T. dorsalis scapulae). (ae) Anterior circumflex artery of humerus (A. circumflexa humeri anterior). (af) Posterior circumflex artery of humerus (A. circumflexa humeri posterior) . Veins. (a) Axillary vein (V. axillaris). (Spalteholz, Fig. 492.) (aa) Lateral thoracic vein (V. thoracalis lateralis}. (aaa) Thoraco-epigastric vein (V. thoraco-epigastrica). (aab) Costo-axillary veins (Vv. costo-axillares). (ab) Brachial veins (Vv. brachiales). (ac) Cephalic vein (V. cephalica). (aca) Thoraco-acromial vein (V. thoraco-acromialis). (ad) Other tributaries corresponding to branches of axillary artery. Nerves. At this stage of the dissection the relation of a group of nerves to the A. axillaris should be closely observed, the full study of the brachial plexus and its branches being made a little later. Note then the relations of — (a) Ulnar nerve (N. ulnaris). (b) Medial cutaneous nerve of upper arm (N. cutaneus brachii me- dialis) (0. T. lesser internal cutaneous, or nerve of Wrisberg). (c) Medial cutaneous nerve of forearm (N. cutaneus antibrachii me- dialis) (0. T. internal cutaneous). (d) Radial nerve (N. radialis) (0. T. musculospiral). (e) Axillary nerve (N. axillaris) (0. T. circumflex). (/) Median nerve (N. medianus), with its two heads. (g) Musculocutaneous nerve (N, musculocutaneus) . Shape and Boundaries of Fossa Axillaris. Describe the form of the fossa. What is the position of its apex? How many walls has it? What structures help to form the anterior wall ? What structures enter into the formation of the posterior wall? Examine carefully the structures consti- tuting respectively the medial and lateral walls of the fossa. Coracoclavicular Fascia (Fascia coracoclavicularis). Divide the pars clavicularis of the M. pectoralis major close to the clavicle (leaving the pars sternocostalis for the present intact) and reflect it downward and lateral ward, avoiding injury DISSECTION OF THE UPPER EXTREMITY 65 to the vessels and nerves beneath. The coracoclavicular fascia is now exposed. What are its attachments? How does it form a sheath for the M. subclavius ? Divide the anterior layer of the sheath transversely close to the clavicle and expose the M. sub- clavius ; observe the N. subclavius entering the deep surface of the latter ; with the handle of the scalpel demonstrate the attach- ment of the posterior layer of the sheath behind the muscle. The portion of the fascia extending between the clavicle and the M. pectoralis minor is often called the " costocoracoid mem- brane. ' ' Piercing this portion of the fascia find the following : (a) Acromiothoracic artery (A. acromiothoracalis) (0. T. thoracic axis). (aa) Acromial ramus (ramus acromialis) . (ab) Acromial network (rete acromiale). (ac) Deltoid ramus (E. deltoideus) (0. T. humeral branch). (ad) Pectoral rami (Rr. pectorales). (b) Acromiothoracic vein (V. acromiothoracalis}. (c) Cephalic vein (V. cephalica). (d) Lateral anterior thoracic nerve (N. thoracalis anterior lateralis). Divide the pars sternocostalis of the M. pectoralis major about its middle and reflect it lateralward and medialward. Pre- serve the branches of the anterior thoracic nerves entering the deep surface of the muscle ; some of them have already passed through the M. pectoralis minor. Note that the sheath of the M. pectoralis minor is formed by a splitting of the fascia coracoclavicularis and that the fascia is continued from the lower margin of the muscle to become continuous with the fascia axillaris. Smaller Pectoral Muscle (M. pectoralis minor). Clean the external surface of the muscle by removing the an- terior layer of the investing fascia. Examine carefully its form, position, origin, insertion, action, and innervation, but do not reflect the muscle until later. Axillary Blood-vessels. Remove the so-called costocoracoid membrane, — viz., that portion of the fascia coracoclavicularis which extends between the clavicle and the upper border of the M. pectoralis minor. The fossa axillaris may now be entered from above. Remove any visible areolar tissue and fat and study carefully in this situation the relations of the axillary artery and vein to one another and to the large bundle of nerves. Note that all are 5 66 LABORATORY MANUAL OF HUMAN ANATOMY enclosed in a tough sheath (prolongation of fascia praeverte- bralis). Clean the axillary blood-vessels carefully and study them. Into what three parts is it customary arbitrarily to subdivide Cviii ci Plexus cervicobrachialis. (After P. Eisler, from Rauber's Text-Book.) Ventral view. h, N. hypoglossus; dh, ramus descendens N. hypoglossi, which, along with dc, the ramus de- scendens cervicalis, forms the ansa hypoglossi ; om, N. occipitalis minor ; au, N. auricularis magnus ; sec, N. cutaneus colli ; a, to N. accessorius ; spc, Nn. supraclaviculares ; p, N. phrenicus ; ds, N. dorsalis scapulae; sps, N. suprascapularis ; ss, Nn. subscapulares ; sc, N. subclavius; ax, N. axillaris; co, N. to M. coracobrachialis ; It, N. radialis; me, N. musculocutaneus ; M, N. medianus; ta, Nn. thoracales anteriores ; tt, N. thoracalis longus ; U, N. ulnaris ; cm, N. cutaneus antibrachii medialis ; ci, N. cutaneus brachii medialis ; ih, N. intercostobrachialis. (From Barker, The Nervous System, New York, 1899, p. 324, Fig. 186.) the axillary artery? Study the relations of each of these three portions. What branches come from the first portion? What from the second! What from the third! Clean each of these DISSECTION OF THE UPPER EXTREMITY 67 branches carefully and follow them to their terminations, com- paring their behavior with the text-book descriptions. Deal simi- larly with the axillary vein and its tributaries. Subclavius Muscle (M. subclavius). Clean it. Examine its form, position, origin, insertion, action, and innervation. With a small hand-saw excise the middle third of the clavicle. Eeflect the M. subclavius. Brachial Plexus (Plexus brachialis). (Fig. 17.) Divide the M. pectoralis minor four centimetres from the coracoid process and reflect the two portions lateralward and medialward respectively, avoiding injury to the medial anterior thoracic nerve. Examine the continuity of the axillary artery and vein with the subclavian artery and vein. Ligature the ar- tery in two places at level of clavicle and cut between. Cut vein similarly. Turn axillary vessels downward. Clean thoroughly the nerves making up the brachial plexus. Study carefully the formation of the plexus, using the cadaver before you, Tra- mond's models, and text-book descriptions. Does the plexus in your cadaver differ from the type ordinarily described? If so, how? Make a careful drawing of the plexus in your subject, with its various branches, labelling each neatly. Note that the plexus can be divided into a supraclavicular portion (pars supraclavicularis) and an infraclavicular portion (pars infra- clavicularis) . All the short branches are counted as belonging to the former, even though they do not actually come off until the trunks are below the clavicle. In conjunction with the dissector of the head and neck, study the Pars supraclavicularis. (a) Posterior thoracic nerves (Nn. thoracales posteriores). (aa) Dorsal nerve of scapula (N. dorsalis scapulae) (0. T. nerve to rhomboids). (ab) Long thoracic nerve (N. thoracalis longus) (0. T. external respiratory nerve of Bell). (b) Anterior thoracic nerves (Nn. thoracales anteriores). (ba) Lateral (0. T. external). (bb) Medial (0. T. internal). (c) Subclavian nerve (N. subclavius). (d) Suprascapular nerve (N. suprascapularis) . (e) Subscapular nerves (Nn. subscapulares) . (f) Thoracodorsal nerve (N. thoracodorsalis) (0. T. middle or long subscapular) . (g) Axillary nerve (N. axillaris) (0. T. circumflex). 68 LABORATORY MANUAL OF HUMAN ANATOMY The dissector of the arm next studies the Pars infraclavicularis. (a) Lateral cord (fasciculus lateralis) (0. T. outer cord). (aa) Musculocutaneous nerve (N. musculocutaneus) . (ab) Lateral or upper head of median nerve (N. medianus). (b) Medial cord (fasciculus medialis) (0. T. inner cord). (ba) Medial or lower head of median nerve (N. medianus). (bb) Ulnar nerve (N. ulnaris). (be) Medial cutaneous nerve of forearm (N. cutaneus anti- brachii medialis) (0. T. internal cutaneous). (bd) Medial cutaneous nerve of upper arm (N. cutaneus brachii medialis) (0. T. lesser internal cutaneous, or nerve of Wrisberg) . (c) Posterior cord (fasciculus posterior). (ca) Axillary nerve (N. axillaris) (0. T. circumflex, really supraclavicular ) . (cb) Radial nerve (N. radialis) (0. T. musculospiral). In order to get a good view of the posterior cord and of the Nn. sub- scapulares, the lateral and medial cords should be divided and reflected downward. Anterior Serratus Muscle (M. serratus anterior) (O. T. Serratus Magnus). Divide the posterior cord of the brachial plexus. Drag the arm forcibly from the body so as to put the M. serratus anterior on the stretch. Clean this muscle thoroughly and study carefully the exact course and distribution of the N. thoracalis longus and the A. thoracalis lateralis. Study the exact form, position, origin, insertion, action, and innervation of the M. serratus anterior. (Spalteholz, Fig. 311.) [When the student has completed this dissection of the ante- rior thoracic region and axillary fossa and has dissected that part of the back to which he is entitled, he may remove the upper extremity from the body and continue the dissection at a side- table. Cut through the Mm. serratus anterior, omohyoideus, and latissimus dorsi, the transverse and dorsal arteries of the scapula, and the Nn. suprascapularis et dorsalis scapulae.] REGION OF THE SHOULDER. Skin and Superficial Fascia. Place a block in the axillary fossa, and, beginning in front, dissect the skin off the anterior and lateral aspects of the shoul- der as far down as the insertion of the M. deltoideus. Eemove no fat with the skin. In the superficial fascia find the following : DISSECTION OF THE UPPER EXTREMITY 69 FIG. 18. Nn. supraclaviculares. N. cutaneus brachii medialis N. cutaneus brachii posterior (from the N. radialis) N. cutaneus antibracb dorsalis (from the N. radialis) N. cutaneus brachii lateralis (from the N. axillaris) Ramus ulnaris of the N . cutaneus antibrachii medialis The cutaneous nerves of the posterior surface of the shoulder and of the arm. (After Toldt, Anat. Atlas, Wieu., 1903, 3 Aufl., p. 831, Fig. 1264.) 70 LABORATORY MANUAL OF HUMAN ANATOMY Arteries. (a) Cutaneous rami of ramus acromialis and ramus deltoideus of A. thoraco-acromialis. Veins. (a) Tributaries of cephalic vein. Nerves. (Fig. 18.) (a) Posterior supraclavicular nerves (Nn. supraclaviculares poste- riores) (0. T. sup ra-acromial branches). (6) Lateral cutaneous nerve of the upper arm (N. cutaneus brachii lateralis) (0. T. cutaneous branch of circumflex). Look for the trunk of this hooking around the posterior margin of M. del- toideus five centimetres above its insertion; dissect it carefully throughout its course in the superficial fascia. Deep Fascia. Eemove the superficial fascia and study the appearance and attachments of— (a) Deltoid fascia (fascia deltoidea). (b) Subscapular fascia (fascia subscapularis) . (c) Supraspinous fascia (fascia supraspinata) . (d) Infraspinous fascia (fascia infraspinata). Deltoid Muscle (M. deltoideus) and the So-called Quadrilateral and Triangular Spaces. Hold the scapula down with hooks to make the fibres of the deltoid muscle tense, and carefully remove the deep fascia from its surface. Study carefully the form, position, origin, insertion, action, and innervation of the muscle. Note especially the three parts of the muscle corresponding to the three distinct muscles in the cat, — deltoclavicular, delto-acromial, and deltospinal of Strauss-Durckheim. How does the texture of the middle portion (delto-acromial) differ from that of the anterior and posterior portions? (Of. Poirier et Charpy, Fig. 83.) Look for a subcu- taneous acromial bursa (bursa subcutanea acromialis). (Of. Spalteholz, Fig. 349. ) Does one exist in your cadaver ? Place the posterior surface of the limb on the table, and examine the area through which the A. circumflexa humeri pos- terior and the N. axillaris pass to the back part of the shoulder. How is this area, "quadrilateral space," bounded above, below, lateralward, and medialward? Clean the surfaces and edges of the muscles of this region. What is the so-called "tri- angular space?" How is it bounded above, below, and lateral- ward? Follow the A. circumflexa scapulae (0. T. dorsalis scapulae) through this space. Place the anterior surface of the limb on the table, and ex- amine the boundaries of the quadrilateral and triangular spaces from behind. DISSECTION OF THE UPPER EXTREMITY 71 Divide the M. deltoideus close to its origin and reflect it downward, avoiding injury to the ramus acromialis of the A. thoraco-acromialis. Examine carefully the subdeltoid bursa (bursa subdeltoidea) and the subacromial bursa (bursa sub- acromialis). Beneath the deltoid dissect out carefully— (a) Posterior circumflex artery of humerus (A. circumftexa humeri pos- terior). (b) Anterior circumflex artery of humerus (A. circumftexa humeri an- terior). (c) Veins corresponding to these arteries. (d) Axillary nerve (N. axillaris) (0. T. circumflex). (da) Muscular rami (rami musculares). (daa) N. teres minor. (dab) Nn. deltoidei. (db) Lateral cutaneous nerve of the upper arm (N. cutaneus brachii lateralis). Teres Major Muscle (M. teres major) ("Larger Round Muscle"). Study carefully its form, position, origin, insertion, action, and innervation. Note especially the torsion the muscle un- dergoes. Review the relation of this muscle to the quadrilateral and triangular spaces. Between the tendon of insertion and the bone find the bursa of this muscle (bursa M. teretis ma- joris). Between the tendon of the M. teres major and that of the M. latissimus dorsi find the bursa of the latter muscle (bursa M. latissimi dorsi). Do you find any trace of a M. dorsi-epitrochlearis ? Examine carefully at this stage the exact mode of termination of the tendons of the Mm. pectoralis major and latissimus dorsi. Ligaments of Shoulder-blade and Acromioclavicular Articulation. Ligaments of the shoulder-blade. Study — (a) Coraco-acromial ligament (ligamentum coraco-acromiale) . (b) Superior transverse ligament of scapula (Lig. transversum scapulae inferius). (The latter will be seen at a later stage of the dissection.) Acromioclavicular articulation (articulatio acromioclavicularis) . Study — (a) Joint-capsule (capsula articulari$) . (b) Acromioclavicular ligament (ligamentum acromioclaviculare) . (c) Intercalated disk of fibrocartilage (discus articularis) . Is one present ? (d) Coracoclavicular ligament (ligamentum coracoclaviculare) . (da) Anterior, lateral, quadrangular part, or trapezoid ligament (Lig. trapezoideum) . 72 LABORATORY MANUAL OF HUMAN ANATOMY (db) Posterior, medial, triangular part, or conoid ligament (Lig. conoideum). Between (da) and (db) look for the bursa of the coraco- clavicular ligament (bursa ligamenti coracoclavicularis) . Deep Muscles of the Shoulder. Saw through the acromion at its junction with the spina scapulae. Cut through the fascia covering the M. teres minor and reflect it medialward; the septum passing from the fascia infraspinata between the M. teres minor and the M. infraspi- natus will be easily found and is the guide in the separation of FIG. 19. Caps, acrom.-clav. Lig. Lig. trapezoid. conoid. Lig. trans, scap. sup. Clavicula Lig. coraco- acromiale Connection of the clavicle with the scapula ; anterior view. (From Poirier et Charpy, Traite" d'Anat. hum., Paris, 1899, 2 ed., t. i. p. 610, Fig. 627.) the two muscles. Avoid injury to the A. circumflexa scapulae between the M. teres minor and the scapula. Clean the following muscles : (a) Supraspinous muscle (M. supraspinatus) . (b) Smaller round muscle (M. teres minor). (c) Infraspinous muscle (M. infraspinatus). (d) Subscapular muscle (M. subscapularis) . Study the form, position, origin, insertion, action, and inner- vation of each. Find the bursa M. subscapularis and with a probe demonstrate its continuity with the synovial cavity of the shoulder- joint. In front of the upper part of the tendon of the M. subscapularis, look for the bursa M. coracobrachialis. DISSECTION OF THE UPPER EXTREMITY 73 Vessels and Nerves behind the Scapula. Cut through the M. infraspinatus three centimetres from its insertion into the tuberculum majus humeri, avoiding injury to vessels beneath. Examine the bursa M. infraspinati between the tendon of insertion of the muscle and the articular capsule of the shoulder-joint. Reflect the main body of the muscle cau- tiously backward and medialward. Cut through the M. supra- spinatus in a similar way and reflect it medialward. Study — (a) Transverse artery of scapula (A. transversa scapulae) (0. T. supra- scapular). Does it pass over or under the Lig. transversum scapulae supe- rius? How is the artery distributed? Find — (aa) Acromial ramus (R. acromialis) going through M. trapezius to rete acromiale. (b) Transverse vein of scapula (V. transversa scapulae). Of what vein is it a tributary? (c) Suprascapular nerve (N. suprascapularis) . Does it pass over or under the Lig. transversum scapulae supe- rius? Review it to its origin from the supraclavicular portion of the brachial plexus. Note especially the branches — (ca) N. supraspinatus. (cb) N. infraspinatus. (d) Circumflex artery of scapula (A. circumftexa scapulae) (0. T. dor- salis scapulae artery). Study its exact course from origin to ter- mination. Note the opportunities for anastomoses about the scapula among its three main arteries — (1) A. transversa colli. (2) A. transversa scapulae. (3) A. subscapularis. Since (1) and (2) come from the A. subclavia (first portion) and (3) comes from the A. axillaris (third portion), the establishment of a collateral circulation after ligation of the subclavian or axil- lary between the origins of the arteries mentioned is seen to be easily possible. DISSECTION OF ARM AND FOEEAEM. Surface Anatomy. The principal features were studied at the beginning of the dissection. The student should now pay attention to certain special points, using his own arm or that of a companion as a control. (a) With the help of the photographs and accompanying key in Gerrish's Anatomy (2d edition, Figs. 971 to 979), identify the surface promi- nences due to the various muscles of the arm and forearm. ( b ) Note that the vena cephalica runs in the sulcus bicipitalis lateralis and the vena basilica in the sulcus bicipitalis medialis. 74 LABORATORY MANUAL OF HUMAN ANATOMY (c) Follow the medial margin (mar go medialis) downward to the medial epicondyle (epicondylus medialis), and the lateral margin (mar go later alis) downward to the lateral epicondyle (epicondylus later- alis). Note that, though the margo lateralis is more salient than the margo medialis, the epicondylus medialis is more prominent than 'the epicondylus lateralis. Feel through the skin behind the medial epicondyle for the groove for the ulnar nerve (sulcus N. ulnaris). Press upon the nerve in your own arm (" funny bone," or " crazy bone"). Whence does the sensation seem to come? (d) Observe the prominence due to the olecranon (1) when the forearm is extended, (2) when the forearm is flexed. Standing in front of a living body, take the two elbow-joints in the palms of the two hands, with the -forefinger resting on the tip of the olecranon, the thumb on the lateral epicondyle, and the middle finger on the medial epicondyle. Ask the person to flex and extend the fore- arms, and notice changes in relative position of bony points. Note the relative distance between the level of the olecranon and the epicondyles. The olecranon is a little nearer to the medial than to the lateral epicondyle, especially in children. Observe the free movement of the skin over the olecranon, due to a subcutaneous bursa. To what extent is the posterior surface of the ulna sub- cutaneous? Feel for the margins of the semilunar notch (incisura semilunaris) . (e) Extend the forearm. Place the thumb of the left hand on the lateral epicondyle of the humerus; seize the hand with your right hand and rotate gently. Feel the rounded head of the radius (capitulum radii) rotating immediately below the epicondyle. (/) In the forearm palpate — (fa) Dorsal margin of ulna (margo dorsalis ulnae). (fb) Styloid process of ulna (processus styloideus ulnae). (fc) Rounded head of ulna (capitulum ulnae). (fd) Styloid process of radius (processus styloideus radii). (fe) Radial artery (A. radialis). (ff) The tendons about the wrist. Skin and Superficial Fascia. Cut through the skin in the middle line of the anterior sur- face of the upper arm and the volar surface of the forearm as far as the wrist. Make a circular incision around the forearm just proximal to the wrist- joint. Remove the skin, dissecting lateralward and medialward, but take none of the fat of the superficial fascia with it. Preserve the skin, as it makes the best primary wrapping for the extremity in the intervals between dissection-periods. In the superficial fascia dissect out carefully the following : Nerves. (Cf. Fig. 20, and Spalteholz, Figs. 792 and 793.) (a) Intercostobrachial nerves (Nn. intercostobrachiales) (0. T. inter- costohumeral). DISSECTION OF THE UPPER EXTREMITY 75 FIG. 20. Clavicula M. subdavius A. subdavia Plexus brachialis (pars infracla vicularis) fasciculi medialis and lateralis Proccssus coracoideus Kami musculares for the M. coracobrachialis N. musculocutaneus M. coracobrachialis - N. medianuB -• N. radialis - A. brachialis N. cutaneus antibrachii medialis M. biceps bracMi V. cephalica— N. cutaneus antibrachii lateralis V. mediana antibrachii . Cartilago costalis 1. V. subdavia N. intercostobrachialis Ramus anastomoticus from the plexus brachialis to the N. / intercostobrachialis ^ Xn. subscapulares N. thoracodorsalis ^M- subscapularis M. teres major _. M. latissimus dorsi -Kami cutanei for the skin of the axillary fossa N. cutaneus brachii medialis Kami musculares of the N. radialis to the ~~Caput longnm ) of the M. caput mediale of > triceps the M. triceps -Oaput mediale ) brachii brachii _ .N. ulnaris -Ramus volaris -Ramus ulnaris M. brachialis V. basilica „ Septum intermusculare mediale V. mediana cubiti Lacertus fibrosus of the N. cutaneus anti- brachii medialis The deep nerves of the shoulder and arm seen from the anterior and medial side. (From Toldt, Anat. Atlas, Wieii, TJU3, 3 Ann., p. 822, Fig. 1254.) 7G LABORATORY MANUAL OF HUMAN ANATOMY (b) Medial nerve of forearm (N. cutaneus antibrachii medialis) (0. T. internal cutaneous). (See Fig. 24, p. 81.) (ba) Anterior cutaneous rami to upper arm (rami cutanei brachii anterior es). (bb) Ulnar ramus (ramus ulnaris) (0. T. posterior branch). (be) Volar ramus (ramus volaris) (0. T. anterior branch). (c) Medial nerve of upper arm (N. cutaneus brachii medialis) (0. T. lesser internal cutaneous, or nerve of Wrisberg). FIG. 21. — Integumentum commune Fascia superficialis Fascia brachii (lamina superficialis) — «r Point where the N. cutaneus antibrachii medialis comes through the fascia brachii Perimysium externum of the M. biceps brachii Fascia brachii (lamina profunda) N. cutaneus antibrachii later Bundle of vessels and nerv Vena Septum intermusculare mediate— N. utnarii Fascia, brachii (lamina superficialis) — Vena cutanea ( V. cephalica) ._ M. biceps brachii Line of uni9n of the lamina superficialis with the lamina profunda fasciae brachii M. brachialis N. radialis M. brachioradialis . Humerus Septum intermusculare laterale M. triceps brachii Fascia superficialis Integumentum commune The structures in the lower third of the arm cut across like stairs. (After Toldt, Anat. Atlas, Wien, 1900, 2 Aufl., p. 264, Fig. 502.) (d) Radial nerve (N. radialis) (0. T. musculospiral). Only super- ficial branches of this nerve are seen as yet. (da) Posterior cutaneous nerve of upper arm (N. cutaneus brachii posterior) (0. T. upper external cutaneous branch of musculospiral). (db) Posterior cutaneous nerve of forearm (N. cutaneus anti- brachii dorsalis) (0. T. lower external cutaneous branch of musculospiral). (e) Musculocutaneous nerve (N. musculocutaneus) . (ea) Lateral cutaneous nerve of forearm (N. cutaneus anti- brachii lateralis) (0. T. terminal cutaneous branch). (See Fig. 24.) DISSECTION OF THE UPPER EXTREMITY 77 Veins. (See also Fig. 24.) (a) Basilic vein (V. basilica}. At what point does it pierce the fascia brachii ? (b} Cephalic vein (V. cephalica}. (c} Median vein of elbow (V. mediana cubiti}, from V. cephalica obliquely upward to V. basilica. Instead of (c) there may be a — (d) Median vein of forearm (V. mediana antibrachii}, bifurcating at head of elbow into — (da} Basilic median vein (V. mediana basilica}, (db) Cephalic median vein (V. mediana cephalica}. In phlebotomy either the V. mediana cubiti or the V. mediana basilica is selected. Note the relations, to these veins, of the lacertus fibrosus, the arteria brachialis, and the ramus volaris of the N. cutaneus anti- brachii median's. FIG. 22. Integumentum commune* Bundle of vessels and nerves _^^__« ,™«^ — \'< IHL rcpfKitii'd Vena basilica -^M£ /^3^^E^£#m\l •Fascia brachii (lamina N.umans—^MOBaaKS^Bm ""•"""" ; -M. brachialis _ -M. brachiodorsalis Humerus ' M. triceps brachii-^HH^^M^H^Septum intermusculare laterale Cross-section of the right arm near its lower end, to show the grouping of the muscles and their relation to muscle-sheaths or fasciae. Half schematic. (After Toldt, Anat. Atlas, Wien, 1900, 2 Aufl., p. 264, Fig. 503.) Lymphatics. (a) Superficial lymph-glands of elbow (lymphoglandulae cubitales superficiales ) . They may be enlarged in infection of the hand or fingers. Deep Fascia of Arm (Fascia brachii) (O. T. Brachial Aponeurosis). (Figs. 21 and 22.) Having isolated the vessels and nerves of the superficial fascia, remove all the fat so as to clean the surface of the deep fascia. Note — (a) Its continuity with the deltoid and axillary fascia above and with the deep fascia of the forearm below. (b) That it is multiply perforated for the passage of vessels and nerves, and (c) The lacertus fibrosus. 78 LABORATORY MANUAL OF HUMAN ANATOMY Make an incision through the fascia brachii along the middle line of the front of the upper arm and a circular incision proxi- mal to the lacertus fibrosus. Reflect the fascia brachii from the front of the arm in two flaps, medial and lateral, until the strong lateral and medial intermuscular septa are reached,— (a) Medial intermuscular septum (septum intermusculare [humeri] mediate) (0. T. internal intermuscular septum). (b) Lateral intermuscular septum (septum intermusculare [humeri] lat- erale) (0. T. external intermuscular septum). Structures in Front of the Intermuscular Septa (Anterior Compart- ment of Arm). (See also Fig. 20.) Arteries. Arrange the axillary artery and vein and the divided nerves of the brachial plexus in their proper order and tie them to a small stick, four centimetres long, placed transversely. Fasten this with a loop of cord to the processus coracoideus. Clean the brachial artery carefully throughout its whole extent and study its relations. (a) Brachial artery (A. brachialis). At what point does it begin? Where and how does it end? With what veins, nerves, and muscles does it enter into relation in the various parts of its course? Study the mode of origin, course, and distribution of the following branches : (aa) Deep artery of upper arm (A. prof undo, brachii) (0. T. superior profunda). Note its relation to the radial nerve. Its branches and general distribution will be studied later. (ab) Superior ulnar collateral artery (A. collateralis ulnaris superior) (0. T. inferior profunda). Note its relation to the ulnar nerve. How does it arise? (ac) Inferior ulnar collateral artery (A. collateralis ulnaris in- ferior) (0. T. anastomotica magna). Note its anterior and posterior divisions. Veins. (a) Brachial veins (Vv. brachiales). (aa) Radial veins (Vv. radiales). (ab) Ulnar veins (Vv. ulnar es}. (ac) Basilic veins (Vv. basilicae), portions beneath fascia brachii. (b) Cephalic vein (V. cephalica), portion in a duplicature of the fascia brachii. Nerves. (a) Medial cutaneous nerve of upper arm (N. cutaneus brachii me- dialis) (0. T. lesser internal cutaneous, or nerve of Wrisberg). (b) Medial cutaneous nerve of forearm (N. cutaneus antibrachii me- dialis) (0. T. internal cutaneous). These nerves (a) and (b) have been studied before, with the exception of their parts subjacent to the fascia brachii. DISSECTION OF THE UPPER EXTREMITY 79 (c) Median nerve (N. medianus). How does it arise? Note its changing relations as regards the A. brachialis. Does it give off any branches above the elbow? (d) Ulnar nerve (N. ulnaris). Study its course in the upper part of the arm. Where and how does it leave the anterior compartment of the upper arm? FIG. 23. Ram. acrom. Aa. circ. hum. A. prof, hum A. thor. sup. ....Ram. pect. ...A. thor. lat. ...A. circ. scap. A. coll. uln. inf. A. rad. recur A. recur, uln. ant. A. rec. uln. post. A. ulnaris A. mediana Scheme of the branches of the brachial artery. (From Poirier et Charpy, Trait6 d'Anat. hum., Paris, 1901, t. ii. p. 732, Fig. 416.) (e) Musculocutaneous nerve (N. musculocutaneus) . Carefully dissect out this nerve and its branches. How does it arise from the plexus brachialis ? Study its exact course throughout the upper arm. (ea) Muscular rami (rami musculares}. (eaa) Nerve to M. coracobrachialis. 80 LABORATORY MANUAL OF HUMAN ANATOMY (eab) Nerve to M. biceps brachii. (eac) Nerve to M. brachialis. (eb) Lateral cutaneous nerve of forearm (N. cutaneus anti- brachii lateralis), already studied. (See Fig. 24.) Note the cutaneous ramus given off above the elbow to supply the skin over the lateral region of the elbow. Muscles. The muscles of the anterior compartment should now be thoroughly cleaned. Study the form, position, origin, insertion, action, and inner- vation of each. (a) Biceps muscle of upper arm (M. biceps brachii). (aa) Long head (caput longum}. The exact origin will be examined later. Observe the prolongation of the syno- vial membrane of the shoulder- joint in the sulcus inter- tubercularis. It is called the intertubercular mucous sheath (vagina mucosa intertubercularis). (ab) Short head (caput breve). The insertion, the lacertus fibrosus, and the bursae related to the tendon of insertion will be examined a little further on. Comparative anatomy indicates that the M. biceps brachii is really a quadrigeminal muscle, — coracoradial, coracocubital, glenoradial, and glenocubital (Krause). (b) Coracobrachial muscle (M. coracobrachialis) . Find the bursa M. coracobrachialis. Note that the M. coraco- brachialis really consists of two distinct bundles; these fuse at their two extremities, but not in the middle, thus forming a tunnel three centimetres long for the N. musculocutaneus. Note that the M. coracobrachialis in the arm corresponds to the ad- ductor system of muscles in the thigh. Find the fibrous arch extending from the insertion of the tendon of the muscle to the inferior border of the tuberculum minus (arch of Struthers). (c) Brachial muscle (M. brachialis) (0. T. brachialis anticus). How is it related to the medial and lateral bicipital sulci? Bend of the Elbow (Cubital Fossa). (Fig. 24.) Dissect in the depth between the M. brachialis and the M. brachioradialis for the radial nerve and the radial recurrent artery. Find the branch of the latter which perforates the sep- tum intermusculare laterale to join the rete articulare cubiti, thus establishing an anastomosis with the A. profunda brachii. Seek the branches from the radial nerve to the M. brachioradialis and the M. extensor carpi radial is longus. Compare the bend of the elbow with the popliteal space. Study the lacertus fibrosus (0. T. semilunar fascia) carefully and examine its relations. Why are these of surgical impor- tance? What is the shape of the space in front of the elbow? How is it bounded ? In this space examine the following : DISSECTION OF THE UPPER EXTREMITY 81 FIG. 24. N. cutaneus f Ramus ulnaris antibrachii medialis { Ramus volaris ji N. cutaneus antibrachii lateralis Ramus superflcialis of the N. radialis - Ramus palmaris N. mediani _- - Ramus cutaneus palmaris of the N. ulnaris The cutaneous nerves of the volar surface of the forearm. (After Toldt, Anat. Atlas, Wien, 1903, 3 Aufl., p. 830, Fig. 1263.) 82 LABORATORY MANUAL OF HUMAN ANATOMY (a) Brachial artery (A. brachialis). (aa) Radial artery (A. radialis). (ab) Ulnar artery (A. ulnaris}. (b) Tendon of M. biceps brachii. Find — (ba) Bursa bicipitoradialis. (bb) Bursa cubitalis interossea. (c) Median nerve (N. medianus). Remove the fat and clean the structures so as to examine in the floor of the space— (a) Brachial muscle (M. brachialis). (b) Supinator muscle (M. supinator) (0. T. supinator brevis). Divide the lacertus fibrosus (0. T. semilunar fascia or bicipi- tal fascia), pull the M. brachioradialis far later alward and the M. pronator teres far medialward. Examine carefully— (a) Radial nerve (N. radialis). (aa) Deep ramus (ramus profundus). (ab) Superficial ramus (ramus superficialis) . (b) Radial recurrent artery (A. radialis recurrens). (c) Inferior ulnar collateral artery (A. collateralis ulnaris inferior) (0. T. anastomotica magna). (d) Anterior ulnar recurrent artery (A. recurrens ulnaris anterior). (e) Epitrochlear lymph-gland. Structures behind the Intermuscular Septa (Posterior Compartment of Arm). Dissect the fascia brachii off the M. triceps, cleaning its three heads thoroughly. This will be facilitated by putting the muscle on the stretch (flex the forearm and raise the inferior angle of the scapula as far as possible). Dissect out the A. profunda brachii and the N. radialis and their branches. Study— (a) Triceps muscle (M. triceps brachii}. Study its form, position, origin, insertion, action, and innervation. (aa) Long head (caput longum). (ab) Lateral head (caput laterals} (0. T. outer head). (ac) Medial head (caput mediale) (0. T. inner head). Compare the M. triceps with the M. quadriceps femoris. Is a M. subanconaeus present? (b) Radial nerve (N. radialis) (0. T. musculospiral nerve). Insert a grooved director or the handle of a scalpel beneath the lateral head of the triceps muscle along the sulcus N. radialis (0. T. musculospiral groove). With this as a guide, cut through the lateral head of the triceps and reflect it medialward and downward. Study the rela- DISSECTION OF THE UPPER EXTREMITY 83 M. trapezius FIG. 25. ^Rami cutanei dorsalcs Nn. thoracalium 'V . tMm. rhomboidei, minor and major M. Icrator scapulae N. dorsalis scapulae Mfprcwpfoafttt M. infraspinatus f . s^prascapularis iiy. transversum scapulae superius Lig. transversum, 'scapulae inferius — Medial axillary space' " (triangular) N. cutaneus brachii lateralis M. triceps brachii Caput medial — Twig for the M. anconaeus and for the elbow-joint N. cutaneus brachii posterior <£ M. deltoideus \Lateral axillary space (quadri- lateral) radialis ^Rami muscu- lares of the N. radialis Caput laterale of the M. triceps brachii Ramus muscularis for the M. brachialis If. brachialis M. brachioradialis N. cutaneus anti- brachii dorsalis The nerves of the muscles about the shoulder-joint and of the M. triceps, together with the cutane- ous branches of the Nn. axillaris and radialis, and the distribution of the N. dorsalis scapulae. The acromion has been sawed off and drawn lateralward and the Mm. supraspinatus and infraspinatus cut through. The lateral head of the M. triceps brachii has been cut through obliquely and its two parts turned back. (After Toldt, Anat. Atlas, Wien, 1903, 3 Aufl., p. 824, Fig. 1256.) 84 LABORATORY MANUAL OF HUMAN ANATOMY tions of the nerve closely in the different parts of the upper arm. Branches in upper arm : (ba) Posterior cutaneous nerve of upper arm (N. cutaneus brachii posterior) (0. T. upper external cutaneous branch of mus- culospiral). (Already studied; vide supra.) (bb) Muscular rami (rami musculares). (bba) To three heads of M. triceps brachii. (bbb) To M. anconaeus. (bbc) To M. brachioradialis (already studied). (bbd) To M. extensor carpi radialis longus (already studied). (bbe) To M. brachialis. (be) Posterior cutaneous nerve of forearm (N. cutaneus anti- brachii dorsalis) (0. T. lower external cutaneous branch of musculospiral. (See Fig1. 28.) (c) Deep artery of upper arm (A. prof undo, brachii) (0. T. superior profunda artery). Study its relations in all parts of its course. Branches : (ca) Deltoid ramus (ramus deltoideus). (cb) Middle collateral artery (A. collateralis media). Note its contribution to the rete articulare cubiti. (cc) Radial collateral artery (A. collateralis radialis) (0. T. artic- ular branch of superior profunda). (cd) Nutrient arteries of the humerus (Aa. nutriciae humeri). These sometimes come from the brachial artery proper. (d) Other structures in back of arm. Dissect carefully above the back of the elbow — (da) Ulnar nerve (N. ulnaris), through the sulcus N. ulnaris. (db) Superior ulnar collateral artery (A. ulnaris collateralis supe- rior) (0. T. inferior profunda). Note relation to rete articulare cubiti. (dc) Ramus muscularis to medial head of M. triceps. This is sometimes called the " ulnar collateral nerve." (dd) Inferior ulnar collateral artery (A. collateralis ulnaris infe- rior) (0. T. anastomotica magna). Look for it beneath the tendon of the M. triceps, a little above the olecranon. (de) Bursa subtendinea olecrani. Look for a bursa subcutanea olecrani also and a bursa intratendinea olecrani. SHOULDER-JOINT (ARTICULATIO HUMERI, OR AR- TICULATIO SCAPULOHUMERALIS). This joint is an enarthrosis. (What is meant by this state- ment!) Review the muscles related to the joint and then remove them as follows : Cut through the origins of the M. coracobrachialis and the caput breve of the M. biceps brachii; divide the M. teres major DISSECTION OF THE UPPER EXTREMITY 85 midway between its origin and its insertion and the caput longum of the M. biceps four centimetres below its origin. Reflect these muscles. Carefully dissect from the capsule of the joint the Mm. supraspinatus, infraspinatus, teres minor, and subscapularis. FIG. 26. Cavity of the articulatio acromioclavicularis Clavicula -£-' M. supraspinatus Labrum glenoidale Bursa subdel- toidea M. deltoideus M. triceps Synovia! membrane and joint-capsule M. teres major Articulatio humeri, frontal section passing through the tuberositas minor, the arm adducted. Poirier et Charpy, Traite d'Anat. hum., Paris, 1899, 2 ed., t. i. p. 624, Fig. 636.) (From Clean the surfaces of the ligaments carefully, lowing : Study the fol- (a) Articular capsule (capsula articularis) . Note its cone shape, the summit attached to the labrum glenoi- dale, its base to the anatomical neck of the humerus. The attach- ment goes beyond the anatomical neck behind and below. Observe the variations in the thickness of the capsule in different parts. (b) Coracohumeral ligament (ligamentum coracohumerale) (0. T. acces- sory ligament). How is it attached medialward and lateralward ? Note that it corresponds to the interval between the tendons of the M. supra- spinatus and M. subscapularis, and so strengthens the capsule in a region otherwise feebly protected. (c) Glenohumeral ligaments. (Cf. Fig. 27.) Dissect off the posterior part of the capsula articularis, pull the bones well apart, look into the joint from behind, 86 LABORATORY MANUAL OF HUMAN ANATOMY and observe the following ligaments ; they are very variable in their development. (ca) Superior glenohumeral ligament (ligamentum glenohumerale superius) (0. T. coracobrachial ligament of Schlemm, supraglenosuprahumeral ligament of Faraboeuf). Note that it with the coracohumeral ligament forms a gutter in which the long head of the M. biceps runs. FIG. 27. Coracoglenoid ligament Lig. coracohumerale M. bizeps Superior glenohumeral ligament J M. subscapularis I y M. infraspinatus Inferior Middle gleno- gleno- humeral humeral ligament ligament M. teres minor Articulatio humeri, posterior view (the posterior part of the capsule and the head of the humerus have been cut away to show the articular surface of the anterior part of the capsule) . (From Poirier et Charpy, Traite" d'Anat. hum., Paris, 1899, 2 ed.( t. i. p. 628, Fig. 639.) (cb) Middle glenohumeral ligament (ligamentum glenohumerale medium) (0. T. Lig. glenoideobrachiale internum of Schlemm or supraglenoprehumeral ligament of Faraboeuf). Between (ca) and (cb) is the interstice known as the "foramen ovale" of Weitbrecht. (cc) Inferior glenohumeral ligament (ligamentum glenohumerale inferius) (0. T. Lig. glenoideobrachiale inferius of Schlemm, pregleno-infrahumeral ligament of Faraboeuf). (d) Glenoid lip (labrum glenoidale) (0. T. glenoid ligament). Divide the capsula articularis and the glenohumeral ligaments in front and pull the head of the humerus away from the glenoid cavity. Examine the labrum glenoidale. Note the relation to it of DISSECTION OF THE UPPER EXTREMITY 87 the long head of the M. biceps brachii above and of the long head of the M. triceps below. (e) Long head of biceps muscle (caput longum M. bicipitis brachii). Note its relations to the joint. Why is it of especial importance? Note its exact mode of origin. While in the joint, surrounded by the synovial membrane, it lies beneath a sort of inverted gutter formed by the superior glenohumeral ligament and by the posterior border of the coracohumeral ligament. [In the horse the tendon is inserted into the external surface of the capsula articularis; in sheep it becomes invaginated in the joint-capsule, is immediately related to the synovial membrane, being swung by a meso of the latter; in higher animals and man it is free in the joint. All these phylogenetic stages are repeated in the ontogeny of the human embryo. (Cf. Welcker, H., Die Einwanderung der Bicepssehne in das Schultergelenk, Arch. f. Anat. u. Physiol., Anat. Abth., Leipzig, 1871, p. 20.)] (/) Synovial membrane and its evaginations. Note exact extent of synovial membrane. Observe the following constant evaginations: (fa) Subscapular bursa, in the adult usually communicating with the M. subscapularis (already studied). (fb) Vagina mucosa intertubercularis (for tendon of long head of biceps muscle). (g) Movements of the joint. What muscles are concerned in the following movements? 1. Flexion. 2. Extension. 3. Abduction. 4. Adduction. 5. Circumduction. 6. Rotation. What structures check excessive movements in the directions mentioned ? What agencies contribute to keeping the joint surfaces in con- tact,— i.e.) to maintaining the integrity of the joint? For the details of the anatomy of this and other joints, consult R. Fick, Handbuch der Anatomic und Mechanik der Gelenke (in Bardeleben's Handbuch), Jena, 1904. FOREARM AND HAND (ANTIBRACHIUM ET MANUS). Superficial Fascia of Dorsum of Hand. Make incisions through the skin along the margo ulnaris and the margo radialis of the hand. Dissect off the skin of the back of the hand (dorsum manus), detaching the flap at the roots of the fingers. Make an incision along the middle line of the dorsum of each digit and reflect the skin radialward and ulnar- ward in each instance. Take no fat with the skin. 88 LABORATORY MANUAL OF HUMAN ANATOMY FIG. 28. N. cutaneus antibrachii dorsalis Ramus ulnaris of the N. cutaneus/' antibrachii medialis Ramus superficialis of the- N. radialis Ramus dorsalis manus of the N. ulnaris Ramus anastomoticus ulnaris Nn. digitales dorsales The cutaneous nerves of the dorsal surface of the forearm and hand. (After Toldt, Anat. Atlas, Wien, 1903, 3 Aufl., p. 831, Fig. 1265.) DISSECTION OF THE UPPER EXTREMITY 89 In the superficial fascia find the following : Nerves. (Fig. 28.) (a) Superficial ramus of radial nerve (ramus superficialis N. radialis) (0. T. radial branch of musculospiral). (aa) Ulnar anastomotic ramus (ramus anastomoticus ulnaris}. (ab) Dorsal digital nerves (Nn. digitales dorsales). (b) Dorsal ramus of hand from N. ulnaris (ramus dorsalis manus N. ulnaris) (0. T. dorsal branch of ulnar nerve). (ba) Dorsal digital nerves (Nn. digitales dorsales). Study exact distribution. FIG. 29. M. flex. poll. long. N. medianus M. palm, long j A. V. and N. inteross. volar. A. ulnarisv \ M. flex. dig. subv \ N. ulnaris M. flex, carpi radialis / M. pronator teres A. radialis M. flex. carpiN ulnaris Vv. ulnares^ M. flex, dig prof. M. brachioradialis Vv. radiales et " N. musculocut. ,-N. radialis -M. ext. carpi rad. long. - -Radius /T " ^M. ext. carpi rad. -«• brevis v * M. supinator (superf. bundle) Ext. digitorum communis M. supinator (deep bundle) M. ext. digiti V. prop. Section passing below the upper third of the forearm. Frozen subject ; right forearm ; segment distal to the cut. (P. Fredet. ) (From Poirier et Charpy, Traite d' Anat. hum., Paris, 1901, 2 ed., t. n. p. 166, Fig. 129.) Ulna M. anconaeus ""^W*": M. ext. carpi ulnaris A. interossea dors. Veins. (a) Venous network of back of hand (rete venosum dorsale manus). (aa) Dorsal metacarpal veins (Vv. metacarpeae dorsales). (aaa) Digital venous arches (arcus venosi digitales). (aaaa) Dorsal digital veins proper (Vv. digi- tales dorsales propriae). Note the relation of these veins to the V. basilica and V. cephal- 90 LABORATORY MANUAL OF HUMAN ANATOMY ica. Observe the communication of the deep veins with these super- ficial veins. Arteries. (a) Dorsal metacarpal and cutaneous rami of dorsal digital arteries (Aa. digitales dorsales, Aa. metacarpeae dorsales). Deep Fascia. Remove all remaining fat of superficial fascia, so as to clean carefully the deep fascia of the forearm and back of the hand. (a) Deep fascia of forearm (fascia antibrachii) . How is it related to the fascia brachii? What becomes of it below? Note the relation of the lacertus fibrosus to this fascia. Look closely at the fibres composing the fascia and note their direc- tion. What nerves and blood-vessels perforate the fascia on the volar and dorsal surfaces of the forearm? Besides those already mentioned find (1) ramus cutaneus palmaris N. ulnaris, (2) ramus palmaris N. mediani, and (3) ramus superftcialis N. radialis. (See Fig. 24.) (b) Deep fascia of back of hand (fascia dor sails manus). Is it as thick as the fascia antibrachii? Note its attach- ment proximalward to the ligamentum carpi dorsale and distalward to the fibrous sheaths of the extensor tendons. The deeper connections of the fascia may be studied later. (ba) Dorsal ligament of the wrist (Lig. carpi dorsale) (0. T. posterior annular ligament). What are its relations proxi- malward and distalward? Ascertain exactly its attach- ments to the radius. What becomes of the ligament ulnar- ward ? Radial Artery and its Relations in the Forearm (A. radialis). Turn aside the ramus volaris of the N. cutaneus antibrachii medialis, the N. cutaneus antibrachii lateralis, and the super- ficial veins. Dissect off the fascia antibrachii, but take care not to disturb the nerves going to the palm. Where muscle-fibres arise from its deep surface, do not remove the fascia. Note care- fully the attachments of the fascia antibrachii in the depth. Dis- sect out the radial artery and its branches in the forearm, clean- ing the adjacent muscles, but disturbing the relations as little as possible. Where does the artery begin? Note exact relations to various muscles in different parts of its course. Between what tendons does that portion of the artery usually palpated in taking the pulse lief Note the relations of the radial artery to the radial veins (Vv. radiates) and to that part of the super- ficial ramus of the radial nerve beneath the fascia antibrachii. Study the origin and distribution of the following branches : DISSECTION OF THE UPPER EXTREMITY 91 FIG. 30. Fascia brachii -. V. cephalica^J ^.Vasa lymphatica superficialia basilica ^_ Lymphoglandulae cubitales superflciales A. brachialis and Vv. brachiales.^ Tendon oj the M. biceps brachii... \ , Lymphoglandulae cubitales profundae Vasa lymphatica profunda J Fascia antibrarhn — 5 L-_,Vasa lymphatica superficialia Arched lymphatic vessels passing on to the dorsum manus N Region of origin of the vasa lymphatica / superficialia of the volar side of the forearm Arcus volaris superficialis Lymphatic vessels of the thumb. Lymphatic vessels of the finger passing on to the back of the hand Aponeurosis palmar is \— Lymphatic vascular network in the subcutaneous fatty tissue of the vola manus Subcutaneous adipose tissue o/ the finger Lymphatic vessels of the volar surface of the forearm and hand. In front of the elbow the fascia has been divided to expose the deep lymphatic vessels and glands. (After Toldt, Anat. Atlas, Wien, 1900, 2 Aufl., p. 705, Fig. 1087.) 92 LABORATORY MANUAL OF HUMAN ANATOMY (a) Radial recurrent artery (A. recurrens radialis). (b) Superficial volar ramus (ramus volaris superficialis) . (c) Muscular rami (rami musculares). (d) Volar carpal ramus (ramus carpeus volaris) (0. T. anterior radial carpal). The other branches of the A. radialis are studied subsequently. Radial Nerve (N. radialis) (O. T. Musculospiral) in the Forearm. (a) Deep ramus (ramus profundus). (aa) Muscular rami (rami musculares). FIG. 31. FCR *** •' A », •j — . iA ffl Ra CR at f/PC FCU Transverse section through the forearm of the opossum. ai, anterior interosseous nerve ; C, M. centralis; CR, M. condyloradialis ; CU, M. condylo-ulnaris; FCR, M. flexor carpi radialis ; FCU1, FCU,2 lateral and medial portions of the M. flexor carpi ulnaris ; m, median nerve ; PL, M. palmaris longus ; R, radius ; Ra, M. radialis ; U, ulna ; u, ulnar nerve ; UL, M. ulnaris. The shaded areas represent the M. flexor sublimis digitorum. (After McMurrich, Amer. Jour, of Anat., Baltimore, 1903, vol. ii., No. 2, p. 196, Fig. 5.) (b) Superficial ramus (ramus superficialis) (0. T. radial branch of mus- culospiral ) . The branches of (a) and (b) are studied later. Superficial Muscles of Volar Surface and Ulnar Margin of Forearm. All the superficial muscles of the forearm should now be dissected out and cleaned. Avoid injury to the sheath of the flexor tendons in the lower part of the forearm (vagina tendinum Mm. flexorum communium). Note that the tendon of the M. DISSECTION OF THE UPPER EXTREMITY 93 palmaris longus runs in front of the ligamentum carpi trans- versum (0. T. anterior annular ligament). The ulnar artery and nerve also run superficial to the ligamentum carpi trans- versum, though under cover of the more superficial ligamentum carpi volare. (Cf. Spalteholz, Figs. 362 and 363.) Study care- fully the form, position, origin, and innervation of each of the following muscles : (a) Brachioradial muscle (M. brachioradialis) (0. T. supinator longus). This will be studied more particularly later, when the back and radial margin of the forearm are dissected. FIG. 32. Transverse section through the forearm of a human embryo of 4.5 cm. ai, anterior interosseous nerve ; C, M. centralis ; CR, M. condyloradialis ; CU, M. condylo-ulnaris ; FCR, M. flexor carpi radialis; FCU, M. flexor carpi ulnaris; m, median nerve; PL, M. palmaris longus; It, radius; Ra, M. radialis; U, ulna; u, ulnaf nerve; UL, M. ulnaris. The shaded areas represent the M. flexor sublimis digitorum. (After McMurrich, Amer. Jour, of Anat., Baltimore, 1903, vol. ii., No. 2, p. 200, Fig. 8.) (b) Long palmar muscle (M. palmaris longus). (c) Round pronator muscle (M. pronator teres) (0. T. pronator radii teres). (ca) Humeral head (caput humerale). (cb) Ulnar head (caput ulnare) (0. T. coronoid head). Note relation of ulnar head to median nerve and ulnar artery. (d) Radial flexor muscle of wrist (M. flexor carpi radialis). 94 LABORATORY MANUAL OF HUMAN ANATOMY (e) Ulnar flexor muscle of wrist (M. flexor carpi ulnaris). (ea) Humeral head (caput humerale). (eb) Ulnar head (caput ulnare). What large nerve runs between these two heads'? (/) Superficial flexor muscle of the fingers (M. flexor digitorum sublimis). (fa) Humeral head (caput humerale). (fb) Radial head (caput radiale). Note space between these two heads for the passage of A. ulnaris and N. medianus. (See study of these flexor muscles by Professor McMurrich, of Ann Arbor, in the Amer. Jour, of Anat., Baltimore, vol. ii., No. 2.) Ulnar Blood-vessels and Ulnar and Median Nerves. These structures and their branches should next be carefully studied. Better to expose the ulnar artery, cut through the inter- muscular septum between the M. flexor digitorum sublimis and the M. carpi ulnaris. (a) Ulnar artery (A. ulnaris). Study its origin, course, relations, and the following branches : (aa) Recurrent ulnar arteries (Aa. recurrentes ulnares). (ab) Muscular rami (rami musculares). (ac) Volar carpal ramus (ramus carpeus volaris) (0. T. anterior ulnar carpal). (ad) Dorsal carpal ramus (ramus carpeus dorsalis) (0. T. poste- rior ulnar carpal). (ae) Common interosseous artery (A. interossea communis). (aea) Volar interosseous artery (A. interossea volaris) (0. T. anterior interosseous) (vide infra). (aeb) Dorsal interosseous (A. interossea dorsalis) (0. T. posterior interosseous), to be studied later. (b) Ulnar veins (Vv. ulnares). (c) Ulnar nerve (N. ulnaris). (ca) Palmar cutaneous ramus (ramus cutaneus palmaris). (cb) Dorsal ramus of hand (ramus dorsalis manus) (O. T. dorsal cutaneous). (cba) Dorsal digital nerves (Nn. digitales dor sales), already studied (vide supra}. (cc) Volar ramus of hand (ramus volaris manus) (branches in palm to be studied later). (cd) Rami musculares to M. flexor carpi ulnaris and part of M. flexor digitorum profundus. (d) Median nerve (N. medianus). Reflect the humeral head of the M. pronator teres and the radial head of the M. flexor digitorum sublimis, and study the median nerve throughout its whole course in the forearm. Note its relation to the A. mediana. Examine — (da) Muscular rami (rami musculares) to Mm. pronator teres, flexor carpi radialis, palmaris longus, flexor sublimis digi- torum,— i.e., to all muscles of superficial group except M. flexor carpi ulnaris. DISSECTION OF THE UPPER EXTREMITY 95 N. cutaneus antibrachii dorsalis^ \ I' N. FIG. 33. —M. brachialis —M. biceps brachtt .-Sulcus bicipitalis lateralis N. cutaneus antibrachii lateralis -^ Kami musculares - f Ramus superficialis — N. radialis < ' Ramus profundus _. r Sulcus bicipitalis medialis . A. brachialis ..N. medianus I — Ramus muscularis • A. ulnaris Rami musculares-*^ M. brachioradialis- — . (longus*- Mm. extensor es carpi] radiales } , \. brems._ V. cephalica -\ Branches of the N. cutaneus antibrachii lateralis 'M. pronator teres -M. supinator — M. flexor carpi radialis M. palmaris longus L flexor carpi ulnaris F A. radialis Ramus cutaneus - __Caput radiale of the M. flexor digitorum sublimis Ramus superficialis of the_. N. radialis .. Fascia antibrachii Ramus cutaneus palmaris of the N. ulnaris Small branches from the N. cutaneus antibrachii lateralis to the wrist Terminal branches of the N. cuta- neus antibrachii lateralis t!Ag. carpi volare .-Ramus profundus of the N. ulnaris N. ulnaris (ramus superficialis ) Ramus palmaris N. mediani, ^M. palmaris brevis A. ulnaris/] The deep nerves of the volar side of the forearm. (After Toldt, Anat. Atlas, Wien, 1903, 3 Aufl., p. 826, Fig. 1258.) 96 LABORATORY MANUAL OF HUMAN ANATOMY (db) Volar interosseous nerve of forearm (Ar. interosseus anti- brachii volaris) (0. T. anterior interosseous). (dba) Rami musculares, to be studied a little further on. (dc) Palmar ramus (ramus palmaris N. mediani) (0. T. median palmar cutaneous), already examined (vide supra). Deep Structures on Volar Surface of Forearm. The remaining structures on the volar surface are now to be dissected out and carefully cleaned. Muscles. (a) Deep flexor muscle of fingers (M. flexor digitorum profundus). (b) Long flexor muscle of thumb (M. flexor pollicis longus). (c) Quadrate (or square) pronator muscle (M. pronator quadratus). Blood-vessels. (a) Volar interosseous artery (A. interossea volaris) (0. T. anterior interosseous). (aa) Median artery (A. mediana). (ab) Muscular rami (rami musculares). (b) Volar interosseous veins (Vv. interosseae volares). (Cf. Toldt, Fig. 1063.) Volar interosseous nerve (N. interosseus [antibrachii] volaris) (0. T. anterior interosseous). (a) Muscular rami (rami musculares) to the M. flexor digitorum pro- fundus (lateral or radial part) and M. pronator quadratus. WRIST AND PALM (CARPUS ET VOL A MANUS [PALM A]). Study the surface anatomy first, noting the thenar and hy- pothenar eminences. Palpate the bony prominences in the front of the wrist. To what is each due ? Observe the three prominent furrows in the thick skin of the palm. Note also the transverse sulci on the palmar surfaces of the digits. In what relation do these stand to the metacarpophalangeal articulations and the finger- joints? To reflect the skin make (1) a vertical incision along the middle line of the vola manus and (2) a transverse incision near the metacarpophalangeal junction from the margo radialis to the margo ulnaris of the hand. Reflect the flaps of skin ulnar- ward and radialward respectively, proceeding with caution. Do not reflect the ulnar flap quite to the ulnar margin of the hand until the insertion of the M. palmaris brevis into it has been made out. DISSECTION OF THE UPPER EXTREMITY 97 Superficial Fascia of Palm. Note the subdivision of the fat into lobules. Study — (a) The short palmar muscle (M. palmaris brevis). After examination cut through its origin and reflect it ulnarward, avoiding injury to ulnar artery and nerve. (b) Cutaneous nerves of palm. (ba) Eamus palmaris N. mediani. (bb) Eamus cutaneus palmaris N. ulnaris. (be) Eamus superficialis N. radialis. FIG. 34. Surface markings of the palm of the hand. The thick black lines represent the chief creases in the skin. (After Treves, Surg. Ap. Anat., London, 1889, 4th ed., p. 260, Fig. 26. ) Deep Fascia of Palm (Aponeurosis palmaris). Clean the surface of this and note its three parts. (a) Radial or thenar aponeurosis. (b) Middle or principal palmar aponeurosis. (c) Ulnar or hypothenar aponeurosis. (a) and (c) are relatively thin; (b) is very thick. What is the shape of (b)? To what does the base of the triangle corre- 7 98 LABORATORY MANUAL OF HUMAN ANATOMY spond? Note the distribution of the longitudinal and transverse fibres which constitute it. Examine carefully — (d) Fasciculi transversi (0. T. transverse superficial ligament). Between each two digital slips of the aponeurosis palmaris, note the vessels and nerves. Cut through the fasciculi transversi in order to expose them better. Observe the septa passing into the depth from the margins of (b}. What three compartments are thus formed and what do they contain ? Superficial Volar Arch (Arcus volaris superficialis) (O. T. Superficial Palmar Arch) and Ulnar Artery. Cut through the narrow proximal part of the aponeurosis palmaris, reflect it distalward, and then remove it entirely. Be- move the ligamentum carpi volare and dissect out the ulnar vessels and ramus volaris manus N. ulnaris in the palm. Dissect out also the N. medianus and its branches; avoid injury to the muscular rami near the distal margin of the ligamentum carpi transversum. To follow out the digital vessels and nerves, make an incision along the middle line of the volar surface of each digit and reflect the skin ulnarward and radialward. How is the superficial volar arch formed! Study the ulnar artery and the superficial volar ramus of the radial artery. Where does the ulnar artery give off its deep volar ramus ! On the skin of your own palm draw a line with a colored pencil cor- responding to the position of the arcus volaris superficialis. Branches : (a) Common volar digital arteries (Aa. digitales volares communes) (0. T. palmar digital arteries). (aa) Volar digital arteries proper (Aa. digitales volares pro- priae) (0. T. collateral digital arteries). Note the point where the Aa. digitales volares communes receive the Aa. metacarpeae volares II.-IV. from the deep volar arch. Observe the relations of the digital arteries to the accom- panying nerves ; the relations of the proper digital differ from those of the common digital arteries. Median Nerve in Palm (N. medianus). (Fig. 35.) How does this nerve enter the palm? Note its relations to the ligamentum carpi transversum and to the mucous sheath of the flexor tendons. Study the following branches : (a) Muscular rami (rami musculares) to M. abductor pollicis brevis, M. flexor pollicis brevis (caput superficialis), and M. opponens pollicis. DISSECTION OF THE UPPER EXTREMITY 99 (b) Common volar digital nerves (Nn. digitales volares communes). Three from N. medianus. The second supplies M. lumbricalis II. The third gives off the ramus anastomoticus cum N. ulnari. (ba) Proper volar digital nerves (Nn. digitales volares propriae) (0. T. collateral digital nerves). Seven from N. me- dianus,— FIG. 35. A. radial M. abductor poll, longus- N. medianus l^^^H M. flexor carpi rad. '-^^ M. adductor pollicis brevis M. flexor brevis pollic M. adductor pollicis N. ulnaris R. profundus R. superficialis M. abductor digit! V. •M. flexor brevis digiti V. I — Anastomosis M. interossea dorsalis I. N. digiti volaris •{ Nerves of the volar surface of the hand. (After Gegenbaur, Lehrb. der Anat. des Mensch., Leipzig, 1899, 7 Aufl., Bd. ii. S. 499, Fig. 660.) I. and II. to skin of thumb; III. to skin of radial side of index and to M. lum- bricalis I.; IV. to skin of ulnar side of index; V. to skin of radial side of digitus medius; VI. to skin of ulnar side of digitus medius ; VII. to skin of radial side of digitus annularis. Work one of these out to its two terminals, — (1) volar, V i ^ ''• 100 LABORATORY MANUAL OF HUMAN ANATOMY to the pulp, (2) dorsal, to the bed of the nail. On the terminals find the form of terminal corpuscle known as the Pacinian corpuscle (corpuscula lamellosa [Vateri, Pacini]). Volar Ramus of Ulnar Nerve in Hand (Ramus volaris manus N. ulnaris). (Fig. 35.) Note position of volar ramus of ulnar nerve in wrist (between ligamentum carpi volar e and ligamentum carpi transversum). Observe branching as follows : (a) Deep ramus (ramus profundus). Note its disappearance between M. abductor digiti quinti and M. flexor digiti quinti brevis. It will be studied later. (b) Superficial ramus (ramus super ficialis) . (ba) Ramus muscularis to M. palmaris brevis. (bb) Common volar digital nerve (N. digitalis volaris communis). FIG. 36. Aa. metacarpeae volares Aa. metacarpeae dorsales, II. and III. Tendons of the M. flexor digitorum profundus and Mm. lumbricales M. adductor pollicis^ .^^^^^S^^^^^^f' suPer-Pcial \ Fascia of the back Deep fascia of the palm ^ ^^jJisM l£*\ lUfi ®-.Rffi§wW deeP of the hand ^^S^^^^^m^^i^mma^imm^'i^^' Thenar Arcus volaris superficialis Aponeurosis palmaris Cross-section of the palm of the hand through the bases of the metacarpal bones. Frozen section. Hand pronated. (After Toldt, Anat. Atlas, Wien, 1900, 2 Aufl., p. 621, Fig. 1000.) 1. Ramus anastomoticus cum N. mediani. 2. Rami cutanei to skin of palm. 3. Proper volar digital nerves (Nn. digit ales volares proprii) — VIII. to ulnar side of ring-finger ; IX. to radial side of little finger. (be) Proper volar digital nerve (N. digitalis volaris proprius), — X. to ulnar side of little finger. Find the muscular rami given off by this nerve to the muscles of the hypothenar eminence. Transverse Carpal Ligament (Ligamentum carpi transversum) (O. T. Anterior Annular Ligament). (Cf. Spalteholz, Figs. 363- 365.) Contrary to statements in many books, this ligament is not directly continuous either with the fascia antibrachii or with the DISSECTION OF THE UPPER EXTREMI aponeurosis palmaris. Note its attachments ulna medialward. Study the relations of its deep and supe faces. What is the canal beneath it called and what stru pass through this canal ? Flexor Tendons and their Mucous Sheaths. (Cf. Spalteholz, Fig. see.) (a) Mucous sheath of common flexor tendons (vagina [mucosa] tendinum Mm. flexorum communium) (0. T. synovia! sheath). If uninjured by dissection thus far, insert a blow-pipe into sheath proximal to ligamentum carpi transversum and inflate. Study the exact relations to the flexor tendons in your cadaver and compare with text-book descriptions. (Cf. Fig. 37.) FIG. 37. Palmar synovial sheaths (vaginae tendinum), normal adult type. (From Poirier et Charpy, Trait6 d'Anat. hum., Paris, 1901, 2 ed., t. ii. p. 190, Fig. 147.) (b) Mucous sheath of tendon of long flexor of thumb (vagina tendinis M. ftexoris pollicis longi). (c) Digital sheaths of the tendons (vaginae tendinum digitales). Note also the pairs of small folds extending between the first and second phalanges and the digital sheaths; these are the so- called "bands of union of the tendons" (vincula tendinum). They carry the blood-vessels to the tendons. 102 LABORATORY MANUAL OF HUMAN ANATOMY Study the ligaments of the sheaths of the fingers (ligamenta vaginalia digitorum manus} and the accessory ligaments. Of the latter, examine (1) the ring-ligaments (ligamenta annularia digi- torum manus) and (2) the cruciate ligaments (ligamenta cruciata digitorum manus). (Spalteholz, Fig. 363.) Cut through these ligaments and open up the digital sheaths of the tendons. The vincula tendinum are well seen on raising the tendons from the phalanges. (d) Flexor tendons and their insertions. (Fig. 38.) Cut through the ligamentum carpi transversum by a vertical incision at its middle, thus opening the carpal canal (canalis carpi). Examine the arrangement of the flexor tendons and dissect each free from the vagina tendinum. Compare the arrangement found with the description in your systematic text-book. Note the rela- tion of these tendons to the central compartment of the palm. Examine carefully the insertions of the tendons of the various flexor muscles. Where and how are the tendons of the superficial flexor perforated by those of the deep flexor? What is meant by the chiasm of the tendons (chiasma tendinum) ? FIG. 38. Os metacarpale Tendon of the M. flexor digitorum subfimis M. lumbricalia Tendon of the M. flexor digitorum profundus The terminal parts of the flexor and extensor tendons of the right middle finger, seen from the radial side. (After Toldt, Anat. Atlas, Wien, 1900, 2 Aufl., p. 323, Fig. 565. ) Follow the tendon of the M. flexor pollicis longus. Open the vagina tendinis and see how and where the tendon is inserted. What is its relation to the muscles of the thenar eminence1? Lumbrical Muscles (Mm. lumbricales). Cut through the arcus volaris superficialis on the ulnar side distal from the deep volar ramus of the ulnar artery, and on the radial side at its junction with the superficial volar ramus of the radial artery. Beflect the arch distalward. Cut through the N. medianus at the level of the wrist and reflect it radialward and distalward, noting again its branches to the muscles of the thenar eminence and the two (radial) Mm. lumbricales. Cut through the M. flexor digitorum sublimis at middle of forearm and reflect it and its tendons distalward as far as possible. Examine thor- oughly the tendons of the M. flexor digitorum profundus and the DISSECTION OF THE UPPER EXTREMITY 103 Mm. lumbricales. Study origin, insertion, form, position, action, and innervation of each of the four lumbrical muscles. Divide the M. flexor digitorum profundus in its muscular part in the forearm and reflect it far distalward, along with the Mm. lum- bricales. Take this opportunity to secure the branches of the ramus profundus of the ramus volaris manus of the N. ulnaris supplying the two (ulnar) lumbrical muscles. Short Muscles of Thumb and Little Finger. Study carefully the form, position, origin, insertion, action, and innervation of each of the following muscles : (a) Short abductor muscle of thumb (M. abductor pollicis brevis) (0. T. abductor pollicis). (b) Abductor muscle of little finger (M. abductor digiti quinti). (c) Short flexor muscle of little finger (M. flexor digiti quinti brevis). (d) Opposing muscle of thumb (M. opponens pollicis). (e) Short flexor muscle of thumb (M. flexor pollicis brevis). (f) Adductor muscle of thumb (M. adductor pollicis). (g) Opposing muscle of little finger (M. opponens digiti quinti). Deep Ramus of Volar Ramus of the Hand from the Ulnar Nerve (R. profundus R. volaris manus N. ulnaris). Study- (a) Muscular rami (rami musculares) to all muscles of palm lying ulnar- ward from tendon of M. flexor longus pollicis (except two radial Mm. lumbricales). Deep Volar Arch (Arcus volaris profundus) (O. T. Deep Palmar Arch). (See Fig. 34.) How is it formed! (Cf. Spalteholz, Fig. 460.) Compare its convexity with that of the superficial volar arch. With a colored pencil indicate its position on your own palm. Study carefully its relation to neighboring muscles and nerves. Cut through the M. adductor pollicis at its origin and reflect it. Follow out care- fully each of the four following branches : (a) Volar metacarpal arteries (Aa. metacarpeae volares). (aa) A. metacarpeae volaris I. (aaa) Branch to thumb (0. T. arteria princeps pollicis). (aab) Branch to radial side of index-finger (0. T. arteria radialis indicis). (ab) A. metacarpea volaris II. (0. T. first palmar interosseous), forward between second and third phalanges to join A. digitalis communis. 104 LABORATORY MANUAL OF HUMAN ANATOMY (ac) A. metacarpea volaris III. (0. T. second palmar interosseous), forward between third and fourth phalanges to join A. digitalis communis. (ad) A. metacarpea volaris IV. (0. T. third palmar interosseous), forward between fourth and fifth phalanges to join A. digitalis communis. Note rami perforantes given off by each volar metacarpal artery. Study the formation of the volar carpal network (rete carpi volar e) (O. T. anterior carpal rete). DORSAL SURFACE AND RADIAL MARGIN OF FORE- ARM (FACIES DORSALIS ET MARGO RADIALIS ANTIBRACHII). The skin and superficial fascia with their nerves and blood- vessels have already been studied. The fat of the superficial fascia should now be completely removed and the deep fascia studied. Dorsal Portion of Deep Fascia of Forearm (Fascia antibrachii) . How is it attached above and below ! Note the relation of its deep surface to the extensor muscles. The dorsal ligament of the carpus (lig amentum carpi dor sale) (0. T. posterior annular ligament) is really a part of it. Superficial Muscles of Dorsum of Forearm. Dissect away the deep fascia on the dorsum of the forearm, with the exception of that portion of it near the elbow overlying and giving origin to muscles underneath. The ligamentum carpi dorsale should also be preserved. Isolate as far as possible and clean the surfaces of the following muscles : (a) Brachioradial muscle (M. brachioradialis) (0. T. supinator longus). (b) Long radial extensor muscle of carpus (M. extensor carpi radialis longus). (c) Short radial extensor muscle of carpus (M. extensor carpi radialis b rev is). (ca) Bursa M. extensoris carpi radialis brevis (Spalteholz, Fig. 360). (d) Common extensor muscle of fingers (M. extensor digitorum com- munis ) . Study juncturae tendinum later. (e) Proper extensor muscle of fifth finger (M. extensor digiti quinti proprius) (0. T. extensor minimi digiti). DISSECTION OF THE UPPER EXTREMITY 105 (f) Elbow muscle (M. anconaeus). (g) Ulnar extensor muscle of carpus (M. extensor carpi ulnaris). Vessels and Nerves on Dorsum of Forearm. Divide the M. extensor digitorum communis and M. extensor digiti quinti proprius at about the middle of their fleshy bellies and reflect proximalward and distalward. Find the muscular rami from the ramus profundus N. radialis innervating these muscles. Dissect out carefully— (a) Dorsal interosseous artery (A. interossea dorsalis) (0. T. posterior interosseous artery). How does it arise? Follow its course and distribution. (aa) Recurrent interosseous artery (A. interossea recurrens) (0. T. posterior interosseous recurrent). (b) Arterial network about the elbow- joint (rete articular -e cubiti). Find the following tributaries : Above. (ba) A. collateralis ulnaris superior. (bb) A. collateralis ulnaris inferior. (be) A. collateralis media. (bd) A. collateralis radialis. Below. (be) A. recurrens ulnaris posterior. (bf) A. interossea recurrens. (bg) A. recurrens radialis. Ulnarward. (bh) Transverse branch fed by A. collateralis ulnaris inferior. (c) Terminal branch of volar interosseous artery (A. interossea volaris) (0. T. anterior interosseous). (d) Deep ramus of radial nerve (ramus profundus N. radialis). (da) Muscular branches (rami musculares). (db) Dorsal interosseous nerve (N. interosseus [antibrachii] dor- salis) (0. T. posterior interosseous). Deep Muscles of Dorsum of Forearm. Clean and study carefully— (a) Supinator muscle (M. supinator) (0. T. supinator brevis). (b) Long abductor muscle of thumb (If. abductor pollicis longus) (0. T. extensor ossis metacarpi pollicis). (c) Short extensor muscle of thumb (M. extensor pollicis brevis) (0. T. extensor primi internodii pollicis). (d) Long extensor muscle of thumb (M. extensor pollicis longus) (0. T. extensor secundi internodii pollicis). (e) Proper extensor muscle of index-finger (M. extensor indicts proprius) (0. T. extensor indicis). Whence does each get its nerve-supply? 106 LABORATORY MANUAL OF HUMAN ANATOMY DORSUM OF WRIST AND HAND. Radial Artery and Veins. Study- (a) Radial artery (A. radialis). (aa) Dorsal carpal ramus (ramus car pens dor sails) (0. T. pos- terior radial carpal). (ab) First dorsal metacarpal artery (A. metacarpea dorsalis I.). (aba) Aa. digitales dor sales. (1) A. dorsalis pollicis ulnaris. (2) A. dorsalis indicis. (ac) Dorsal digital artery to radial side of thumb (A. dorsalis pol lids ra dia Us). FIG. 39. Tendon of the M. flexor digitorum sublim Tendon of the M. flexor digitorum profundus M. flexor carpi ulnaris - A. ulnaris— N. ulnaris Ramus dorsalis manus — of the N. ulnaris Discus articularis.- Capitulum ulnae Tendon of the M. extensor carpi ulnaris-? Lig. carpi volare Tendon of the M. palmaris longus N. medianus ^.Tendon of the M. flexor carpi radialis ^Tendon of the M. flexor pollicis longuc __ .Ramus volaris superficialis _A. radialis -.M. abductor pollicis longus -M. extensor pollicis brevis -Radius M. extensor carpi radialis longus '..M. extensor carpi radialis brevis — M. extensor pollicis longus Tendon of the M. extensor digiti— V. proprius Lig. carpi dorsale Cross-section of the distal extremity of the right forearm. Surface distal to the cut. (After Toldt, Anat. Atlas, Wien, 1900, 2 Aufl., p. 621, Fig. 999.) Tendons of the Mm. extensor digitorum lommunis and extensor indicis proprius (ad) Dorsal carpal rete (rete carpi dorsale) (0. T. posterior carpal rete). (ada) Dorsal metacarpal arteries (Aa. metacarpeae dor- sales II., III., IV.) (0. T. dorsal interosseous arteries). Note how each of these divides into two dorsal digital arteries (Aa. digitales dorsales) for adja- cent margins of the second to the fifth finger. Find the artery passing directly from the ulnar side of the rete carpi dorsale towards the ulnar margin of the little finger. (b) Radial veins (Vv. radiales). Dorsal Ligament of Wrist (Ligamentum carpi dorsale) (O. T. Pos- terior Annular Ligament). How does it become attached radialward and ulnarward? How is the space beneath it subdivided ? To what are the various septa attached? Open up the following six compartments and study their contents. DISSECTION OF THE UPPER EXTREMITY 107 First Compartment. Tendons of M. abductor pollicis longus and M. extensor pollicis brevis. Vagina tendinum Mm. abductoris longi et extensoris brevis pollicis. Second Compartment. Tendons of Mm. extensor carpi radialis longus et brevis. Vagina tendinum Mm. extensorum carpi radialium. Third Compartment. Tendon of M. extensor pollicis longus. Vagina tendinis M. extensoris pollicis longi. Fourth Compartment. Tendons of M. extensor digitorum communis and M. extensor indicis proprius. Vagina tendinum Mm. extensoris digitorum communis et extensoris indicis. Fifth Compartment. Tendon of M. extensor digiti quinti proprius. Vagina tendinis M. extensoris digiti V. Sixth Compartment. Tendon of M. extensor carpi ulnaris. Vagina tendinis M. extensoris carpi ulnaris. Note the variable extent of the vaginae tendinum into the dorsum manus. (Spalteholz, Fig. 369.) Tendons of Extensor Muscles of Fingers. (Spalteholz, Fig. 361 ; Poirier et Charpy, t. ii., Figs. 109, no.) Note the divergence of the tendons after leaving the osteo- fibrous canals at dorsum of wrist. At level of head of each meta- carpal bone find fibrous expansion going from deep surface of tendon, becoming adherent to capsula articularis, and inserted into base of first phalanx. At this level note union of process of deep palmar fascia with lateral sides of tendon. Note aponeu- rotic expansion at sides of each tendon over first phalanx and find insertions of Mm. interossei and Mm. lumbricales into these. Observe division of tendon (reinforced by " dorsal expansion") into three tongues of fibrous tissue, the middle one becoming directly inserted into base of phalanx II. ; the lateral tongues, stronger, go farther, become united over the second phalanx, and are inserted into the base of phalanx III. (ungual phalanx). Study the aponeurotic bridges (juncturae tendinum) uniting one tendon with its neighbor. Why is the independent movement of the ring-finger backward so limited ? In the thumb, the tendons of the two extensors are placed side by side at the level of the metacarpophalangeal joint and receive the same expansions of the palmar fascia and also interosseous muscles (represented here by the M. abductor pollicis brevis and the M. interosseus I.). 108 LABORATORY MANUAL OF HUMAN ANATOMY Note the exact behavior of the tendons of the M. extensor indicis proprius and the M. extensor digit! quinti proprius at and near their terminations. Dorsal Interosseous Nerve (N. Interosseus dorsalis) (O. T. Pos- terior Interosseous). Find the terminal filament of this nerve. To what structures is it related! What joints are innervated by it? FIG. 40. M. lumbricalis Aponeurotic expansion on ulnar side — Tendon of M. ex- tensor commu- nis digitorum Slip to first phalanx _ Perforating fibres _ M. interosseus Tendons of the M. extensor communis digitorum: connections (deep surface). (From Poirjer et Charpy, Trait<§ d'Anat. hum., Paris, 1901, 2 ed., t. ii. p. 130, Fig. 109.) Transverse Ligament of the Heads of the Metacarpal Bones and the Interosseous Muscles. Place the volar surface of the hand upward and examine the transverse ligament of the heads of the metacarpal bones (liga- DISSECTION OF THE UPPER EXTREMITY 109 mentum capitulorum [ossium metacarpalium] transversum). Note that the Mm. lumbricales run volar and the Mm. interossei dorsal to this ligament. Study the form, position, origin, insertion, action, and inner- vation of — (a) Volar interosseous muscles (Mm. interossei volares I., II., III.). (b) Dorsal interosseous muscles (Mm. interossei dor sales I.-IV.). Eeflect the radial head of the M. interosseus dorsalis I. A good dorsal view of the deep head of the M. flexor pollicis brevis V. mediana basilica --s N. cutaneus anti- brachii medialis --- - N. / medianus ------ 7^ A. of the N. med.-- M. brach. --- M. pronat.. - teres M. palm. long. M. flex. _ sub. dig. A. collat. uln. sup. N. ulnaris - - M. flexor - - carpi ulnaris Bursa subcutanea olecrani FIG. 41. / A. brachialis / /- - V. mediana cephalica . . N. muscnlocutaneus Tendon of the _.M. biceps \ M. brachio- " " " radian's tTV " "N. radialis i-A.recurrens ^ radialis -Capsula articularis -M. extensor carpi rad. longus - - -M. extensor carpi rad. brevis A. interosseus recurrens — Common tendon of origin of extensors — — M. anconaeus Olecranon Transverse section of the left elbow (after Farabo3uf). The distal end of the humerus is seen intact. (From Poirier et Charpy, TraitS d'Anat. hum., Paris, 1899, 2 ed., t. i. p. 645, Fig. 655.) can now be obtained. How does this head arise? Where is it inserted? This part of the M. flexor pollicis brevis was desig- nated by Henle the M. interosseus volaris primus. The course of the tendon of the M. flexor radialis should now be followed and its exact insertion established. JOINTS. Elbow-joint (Articulatio cubiti). (Figs. 41, 42, and 43.) The muscles about the elbow may now be completely removed. Leave the M. supinator in position after removal of the others, in order that its exact origin, insertion, innervation, and mode 110 LABORATORY MANUAL OF HUMAN ANATOMY of action may be made out. It may then be cut away also. What bones are concerned in the formation of the elbow- joint? Note that the articulatio cubiti really includes three articulations : (a) Humero-ulnar articulation (articulatio humero-ulnaris) ; (b) Humeroradial articulation (articulatio humeroradialis) ; (c) Proximal radio-ulnar articulation (articulatio radio-ulnaris proxi- malis ) . Joints (a) and (b) are studied at this stage; joint (c), a little later. FIG. 42. Lig. coll. uln. Capsula articularis (anterior part) Humerqcoronoid fascicle .Olecranohumeral fascicle Ol ecranocoronoid fascicle (Cooper's ligament) Articulatio cubiti. (From Poirier et Charpy, Traite" d'Anat. hum., Paris, 1899, 2 ed., t. i. p. 641, Fig. 650.) Study carefully the form, position, and attachments of each of the following ligaments : (a) Joint-capsule (capsula articularis). (aa) Ulnar collateral ligament (ligamentum collaterale ulnare) (0. T. internal lateral ligament). (ab) Radial collateral ligament (ligamentum collaterale radiale) (0. T. external lateral ligament). Make a transverse cut across the anterior surface of the cap- sula articularis so as to open the joint. Examine the extent of the synovial membrane. Note the continuity of the cavities of the humero-ulnar and humeroradial articulations with that of the proximal radio-ulnar articulation, all forming one joint- cavity, that of the articulatio cubiti. (See Fig. 43.) DISSECTION OF THE UPPER EXTREMITY 111 Study the possible movements of the humeroradial and humero-ulnar articulations. Joint of the Hand (Articulatio manus). Dissect away the whole of the ligamentum carpi transversum and the ligamentum carpi dorsale. Reflect the flexor and ex- tensor tendons distalward, so as to leave the region of the wrist bare. Cut away the short muscles of the thenar and hypothenar eminences. FIG. 43. Labrum ,, falciforme" Articulatio cubiti, frontal section. (From Poirier et Charpy, Traite d'Anat. hum., Paris, 1899, 2 ed., t. L p. 644, Fig. 653.) Note that the joint of the hand is divisible into two chief parts : (a) Radiocarpal articulation (articulatio radiocarpea) (0. T. wrist- joint). (b) Intercarpal articulation (articulatio intercarpea) (0. T. carpal joints). ad (a) What bony articular surfaces are concerned in the radiocarpal articu- lation? Study carefully the following: (aa) Joint-capsule (capsula articularis) . (ab) Strengthening ligaments: (aba) Dorsal radiocarpal ligament (ligamentum radiocar- peum dorsale) (0. T. posterior ligament). (abb) Volar radiocarpal ligament (ligamentum radiocar- peum volare) (0. T. anterior ligament). (abc) Ulnar collateral ligament of carpus (ligamentum 112 LABORATORY MANUAL OF HUMAN ANATOMY collaterale carpi ulnare) (0. T. internal lateral ligament). (abd) Radial collateral ligament of carpus (ligamentum collaterale carpi radiate} (0. T. external lateral ligament). FIG. 44. V. Using the little finger as an axis JII. Using the middle finger as an axis I. Using the thumb as an axis I Supination Pronation Schema of pronation and of supination. On the right side of the figure are reproduced three tracings by the radius and the ulna in the movements of pronation and supination, taking as an axis the thumb (7.) , the middle finger (///.) , and the little finger ( V.) . (The larger curve belongs to the radius, the smaller to the ulna.) (From Poirier et Charpy, Traite d'Anat. hum., Paris, 1899, 2 ed., t. i. p. 658, Fig. 665.) (b) What bony articular surfaces are concerned in the intercarpal articu- lation? Study carefully the following: (ba) Joint-capsules (capsulae articular es) . (bb) Strengthening ligaments : (bba) Radiate ligament of carpus (ligamentum carpi ra- diatum}. (bbb) Dorsal intercarpal ligaments (Ligg. intercarpea dor- salia}. DISSECTION OF THE UPPER EXTREMITY 113 (bbc) Volar intercarpal ligaments (Ligg. intercarpea vo- laria) (0. T. palmar intercarpal). (bbd) Interosseous intercarpal ligaments (Ligg. intercar- pea interossea). To examine these ligaments carefully the ulnar and radial collateral ligaments of the carpus and the dorsal intercarpal ligaments should be cut through. In this connection study also the articulation of the pisiform bone (articulatio ossis pisiformis), examining the following: FIG. 45. Art. raclio-ulnaris distalis Radiocarpal interspace Intercarpal interspace Discus articularis Os triquetrum Carpometacarpal - J£*i§&t^ii8!£a$i;!^ _ _ Lig. carpometacarpale interspace ^^ilJ^w^d^J/M/v! ^** *\^^^^ .min. , il interosseum Lig. basis ( os. meta- carp.) interosseum Frontal section of the radiocarpal, carpal, and carpometacarpal joints. (From Poirier et Charpy, Trait6 d'Anat. hum., Paris, 1899, 2 ed., t. i. p. 660, Fig. 667.) (a) Joint-capsule (capsula articularis}. (b) Strengthening ligaments: (ba) Ligamentum pisohamatum. (bb) Ligamentum pisometacarpeum. How are these related to the tendon of the M. flexor carpi ulnaris, and of what importance are they? Of what movements is the hand capable at the radiocarpal articulation? In how far are these movements favored or in- creased by means of the intercarpal articulation? What muscles 8 114 LABORATORY MANUAL OF HUMAN ANATOMY are concerned in flexion, extension, abduction, and adduction of the hand? Of what especial advantage are the multiple bones and joints of the carpus? Radio-ulnar Joints. (See Figs. 44, 45, and 46.) These joints consist of— (a) Proximal radio-ulnar articulation (articulatio radio-ulnaris proxi- malis) (0. T. superior radio-ulnar). FIG. 46. Tend. M. bicipitis -Chorda obliqua (Lig. of Weitbrecht) .Ligamentum interosseum -Orifice for the A. interossea volaris The interosseous membrane of the forearm, volar surface. (After Poirier et Charpy, Traite d'Anat. hum., Paris, 1899, t. i. p. 655, Fig. 664.) (&) Distal radio-ulnar articulation (articulatio radio-ulnaris distalis) (0. T. inferior radio-ulnar). (c) Interosseous membrane and oblique cord (membrana interossea anti- brachii et chorda obliqua). To expose the ligaments, the muscles must be completely re- moved from the dorsal and volar surfaces of the forearm. (a) Proximal radio-ulnar joint. What bony surfaces are concerned? Study carefully the annular DISSECTION OF THE UPPER EXTREMITY 115 ligament of the radius (ligamentum annulare radii) (0. T. orbicu- lar ligament) and the sacciform recess (recessus sacciformis). (b) Distal radio-ulnar joint. What bony surfaces are concerned? Study carefully — (ba) Joint-capsule (capsula articularis}. (bb) Articular disk (discus articularis) (0. T. triangular fibro- cartilage). (be) Saccular recess (recessus sacciformis). (c) Interosseous membrane and oblique cord. Study exact form and attachments. What vessels and nerves are related to the interosseous membrane? In what movements are the radio-ulnar articulations con- cerned! Study carefully the movements of pronation and supi- nation (a) when the forearm is extended, (b) when it is flexed. What muscles are concerned in these movements ? Saw through the ulna at the junction of its distal and middle thirds ; cut through the membrana interossea. Draw the distal fragment of the ulna medialward ; open the recessus sacciformis. The proximal surface of the discus articularis can be seen and its attachments carefully examined. Carpometacarpal Joints (Articulationes carpometacarpeae). How many of these are there ? What bony surfaces are con- cerned in their formation? In order to examine these joints thoroughly, remove the Mm. interossei from the metacarpal bones and detach the tendons of the flexor muscles and the Mm. lumbricales from the fingers. Do not disturb the extensor ten- dons at present. Clean the carpometacarpal and the intermeta- carpal ligaments carefully. Study in the four ulnar carpometa- carpal articulations the following : (a) Joint-capsules (capsulae articular es] . (b) Strengthening ligaments : (ba) Dorsal carpometacarpal ligaments (ligamenta carpometacar- pea dorsalia). (bb) Volar carpometacarpal ligaments (ligamenta carpometacar- pea volaria). Note the special carpometacarpal joint for the thumb (articulatio carpometacarpea pollicis). Study its capsula articularis. Intermetacarpal Joints (Articulationes intermetacarpeae). These joints are amphiarthroses. What is an amphiarthro- sis ? Study— (a) Joint-capsules (capsulae articulares) . (b) Strengthening ligaments: 116 LABORATORY MANUAL OF HUMAN ANATOMY (ba) Dorsal ligaments of basal extremities of metacarpal bones (Ligg. basium [ossium metacarpalium] dorsalia). (bb) Volar ligaments of basal extremities of metacarpal bones (Ligg. basium [oss. metacarp.] volaria). (be) Interosseous ligaments of basal extremities of metacarpal bones (Ligg. basium [oss. metacarp.] interossea). These fill up the spatia interossea metacarpi and can be studied to better advantage later, when the bases of the metacarpal bones are separated from one another. Before leaving the joints of the carpus and metacarpus, the synovial membranes and articular surfaces of the joint-cavities should be carefully reviewed. (See Fig. 45.) Which joint-cavi- ties are independent? Which communicate? Detach the meta- carpus from the carpus and examine the articular surfaces. Then separate the various bones of the carpus and metacarpus from one another in order to see the extent of the various inter- osseous ligaments and articular surfaces. Study the possible movements in the various joints under examination. What muscles are especially concerned in the various movements ? Metacarpophalangeal Joints (Articulationes metacarpophalangeae). These five joints are arthrodiae. What is an arthrodia? Study- (a) Joint-capsules (capsulae articular es] . (b) Strengthening ligaments: (ba) Collateral ligaments (ligamenta collateralia) , one radial and one ulnar for each joint. (bb) Volar accessory ligaments (ligamenta accessoria volaria) (0. T. palmar ligaments). (c) Transverse ligaments of the heads of the metacarpal bones (Ligg. capitulorum [oss. metacarpalium] transversa). These have already been examined (vide supra). Eaise the extensor tendon from the dorsal aspect of each joint and note the absence of dorsal ligaments, their place being taken by the extensor tendon. Of what movements is each metacarpophalangeal joint capa- ble ? What are the muscles concerned in each case for the differ- ent joints? Joints of the Fingers (Articulationes digitorum manus). Note that the thumb has one, the other digits two ginglymi. What is a ginglymus ? Study— DISSECTION OF THE UPPER EXTREMITY H7 (a) Joint-capsule (capsula articularis) . (b) Strengthening ligaments (ligamenta collateralia), one ulnar, one radial (0. T. lateral ligaments). What muscles are concerned in flexion and in extension of each of these joints ? Review the bones of the upper extremity. Part II DISSECTION OF THE LOWER EXTREMITY LOWER EXTREMITY Introductory. ON the surfaces of the lower extremity mark out the regions (regiones extremitatis inferioris). Make four drawings indi- cating these, one anterior, one posterior, one medial, and one lateral. Make use of Figs. 1 and 2 (pp. 43 and 44). In the thigh (femur) observe the general cylindrical shape, tapering distalward, the prominence in the middle line of the thigh in front due to the M. rectus femoris, and medial from this another due to the M. vastus medialis, extending distalward to the knee-cap. Note the direction of the streams of hairs (flumina pilorum). At the knee (genu) observe the prominent knee-cap (patella). In the leg (crus) note the general shape and the lateral and medial prominences near the ankle (malleoli later alls et me- dialis). In the foot (pes) observe the heel (calx) behind, constituting part of the ankle (tarsus) ; anteriorly, the toes (digiti) ; and between the ankle and the toes, the metatarsus. Among the digits distinguish- ed First or great toe (digitus primus, or hallux). (b) Second toe (digitus secundus). (c) Third toe (digitus tertius). (d) Fourth toe (digitus quartus). (e) Fifth or little toe (digitus quintus). How many phalanges has each digit? Examine the nails (ungues), and distinguish (a) root of nail (radix unguis), (b) free margin (mar go liber), (c) covered margin (mar go occultus), (d) semilunar white area (lunula). On the lateral surface of the lower extremity (fades later- alis) observe the hip (coxa) and thigh (femur), with the iliac crest (crista iliaca) above. Note the general configuration; observe the depression over the trochanter major at the upper extremity of the thigh-bone. On the lateral surface of the knee observe the prominent fold of skin covering the tendon of the biceps muscle, and anterior to this the fold covering the iliotibial band of the fascia. At the ankle the lateral malleolus (malleolus lateralis) is prominent, with a depression (fossa retromalleo- 121 122 LABORATORY MANUAL OF HUMAN ANATOMY laris) behind it. In the foot note that the lateral margin (mar go later alis) rests on the floor when the body is erect. Examine the posterior surface (fades posterior) of the lower extremity. Observe the prominence of the buttocks (dunes or nates), separated from each other by the crena ani and from the thigh by the gluteal fold (sulcus glutaeus) ; behind the knee is the popliteal fossa (fossa poplitea). Examine its boundaries and extent. In the leg note the prominent calf (sura), and lower down the prominence due to the tendon of the calf muscles. In the sole of the foot (plant a) observe the grooves in the skin (sulci cutis) and the ridges (cristae cutis) between. Observe the arch of the foot : it is higher on the medial than on the lateral margin. Note the ball of the great toe and the eminence of the little toe. On the medial surface (fades medialis) of the lower extrem- ity, observe the prominence due to the M. vastus medialis in the thigh, that due to the malleolus medialis at the ankle, and the curved medial margin of the foot (mar go medialis pedis). After inspection the student should resort to palpation of these parts. In addition to what has been mentioned above, note the groove at the groin (sulcus inguinalis) and the depression in the subinguinal region corresponding to a deeper triangle (fossa Scarpae major, trigonum femorale) (0. T. Scarpa's tri- angle). Can you feel the superficial lymph-glands (lympho- glandulae subinguinales superfidales) ? Note the mobility of the skin over the patella, due to a bursa (bursa praepatellaris sub- cutanea). Feel the ligament of the patella (tig amentum pa- tellae) and note the mobility of the skin over it (bursa infra- patellaris subcutanea). Flex and extend the knee-joint. What are the limits of movement? Feel the line of the joint during the movement. Palpate the condyles of the femur and of the tibia. Locate the tuberosity of the tibia and note the mobility of the skin over it (bursa subcutanea tuber ositatis tibiae). Feel the anterior crest of the tibia. How much of it is immediately sub- cutaneous ? Feel the medial surface of the tibia and the tendons of the extensor muscles of the foot. In the front of the foot find the rounded bony prominence of the anterior end of the heel- bone (calcaneus), three or four centimetres anterior to the malle- olus medialis. Just anterior to this note the depression indi- cating the position of Chopart's transverse joint of the ankle (articulatio tarsi transversa [CJioparti]) . Run the finger along the iliac crest. Feel the sciatic tuber- osity (tuber iscMadicum) and also the greater trochanter (tro- chanter major) ; note the mobility of the skin over the latter DISSECTION OF THE LOWER EXTREMITY 123 (bursa subcutanea trochanterica). Draw the shortest possible line on the surface from the tuber ischiadicum to the spina iliaca anterior superior and note the relation which the upper extremity of the trochanter major bears to this line. Palpate the structures forming the boundaries of the popliteal fossa. Note the mobility of the skin over the malleoli (bursa subcutanea malleoli later alls et medialis). Feel the tendons in the retro- malleolar fossa. Palpate the various bony prominences that can be felt about the ankle and foot, and identify each by comparison with the skeleton. GLUTEAL EEGION (REGIO GLUTAEA). Make the following incisions (see Fig. 3) : (1) From the spina iliaca posterior superior along the crista iliaca as far forward as possible. (2) From the posterior extremity of this incision obliquely downward and medialward to the middle line of the sacral region, then vertically downward to the tip of the coccyx. (3) From the tip of the coccyx downward and lateralward over the back of the thigh, intersecting the sulcus glutaeus at its middle point, and terminating a little below the upper third of the thigh. The flap of skin thus formed should now be reflected lateralward, leaving intact the fat immediately beneath. There is now ex- posed to view- Superficial Fascia. Note the abundance of fat. How does the amount of fat contained compare in the male and female? Observe its tough, fibrous character over the tuber ischiadicum. This fascia should now be removed by blunt dissection. Find the following : Nerves. (Fig. 47.) (a) Middle nerves of buttock (Nn. clunium medii). These pierce the glutaeus maximus and the deep fascia in a line passing from the spina iliaca posterior superior to the tip of the coccyx. (&) Superior nerves of buttock (Nn. clunium superior es], crossing the crista iliaca at a point corresponding to the lateral limit of the attachment of the musculus sacrospinalis to the os ilium. (c) Lateral cutaneous ramus of iliohypogastric nerve (ramus cutaneus lateralis nervi iliohypogastrici). It generally crosses the iliac crest opposite a tubercle projecting from its outer lip, about two and one-half inches dorsal to the spina iliaca anterior superior. (d) Lateral cutaneous ramus of last thoracic nerve (ramus cutaneus lateralis N. thoracalis 7.) (0. T. last dorsal nerve). This nerve crosses the iliac crest a short distance anterior to the preceding. 124 LABORATORY MANUAL OF HUMAN ANATOMY FIG. 47. Nn. clunium medii Nn. clunium superiores Kami perineales Twigs of the N. cutaneus femoris ^ posterior Ramus cutaneus of the N. obturatorius Twigs of the N. cutaneus femoris lateralis Nn. clunium inferiores N. cutaneus femoris posterior shining through the fascia lata \Twigs of the N. cutaneus / femoris lateralis Twigs of the N. cutaneus surae lateralis Ramus cutaneus cruris medialis of the_ N. saphenus The cutaneous nerves of the gluteal region and on the posterior side of the thigh. (After Toldt, Anat. Atlas, Wien, 1903, 3 AufL, p. 849, Fig. 1286.) DISSECTION OF THE LOWER EXTREMITY 125 (e) Cutaneous twigs from the posterior cutaneous nerve of the thigh (N. cutaneus femoris posterior) (O. T. cutaneous branches of small sciatic), passing around the lower border of the glutaeus maximus. (ea) Inferior nerves of buttock (Nn. clunium inferior es}. (eb) Perineal branches (rami perineales). (f) Posterior branches of lateral cutaneous nerve of thigh (N. cuta- neus femoris lateralis) (0. T. external cutaneous). These nerves should be traced as far as possible and their distribution carefully noted. Deep Fascia. Remove the remaining portion of the superficial fascia, pre- serving the nerves, and expose the deep fascia. Notice the general character of this fascia anteriorly, where it covers the M. glutaeus medius, and compare it in general characteristics with that portion of the fascia covering the M. glutaeus maximus. After having made a careful study of this fascia, remove it in a continuous layer from above down- ward, after having rendered the muscle tense beneath by ro- tating the thigh medial ward. The borders of the muscle should be carefully defined; note that the thin fascia covering the latter becomes continuous with the dense pearly aponeurosis covering the muscle immediately anterior to it. In dissecting away this fascia, cut always in the direction of the muscle fibres. Glutaeus Maximus Muscle (M. glutaeus maximus). Note carefully the form, position, origin, insertion, action, and innervation of this muscle. What is the relation of the muscle to the dense fibrous band (tractus iliotibialis) passing from the ilium to the tibia? How does the size of this muscle in man compare with that in other animals? After having care- fully examined and drawn this muscle, the student may reflect it in the following manner : The two borders of the muscle should be freed and the hand passed under the muscular mass. Detach the muscle from its attachment to the ilium. Proceed cautiously as the upper margin of the greater sacrosciatic foramen (fora- men ischiadicum ma jus) is approached and avoid the gluteal ves- sels as they pass through this opening. Secure these and detach the muscle from the side of the sacrum, exposing the piriform muscle (M. piriformis) as it emerges from the pelvis. Separate the muscular fibres from the ligamentum sacrotuberosum (0. T. great sacrosciatic ligament) and the side of the coccyx, avoiding 126 LABORATORY MANUAL OF HUMAN ANATOMY the Nn. clunium inf eriores in order that they may later be traced to their source. The few coccygeal arteries passing through the ligamentum sacrotuberosum may be sacrificed. The muscle can now be partially reflected, but is still attached by blood-vessels and nerves entering its under surface. These should now be carefully cleaned. Having studied these last structures, they may be cut away, leaving a small piece of muscle connected to each. The whole muscle may then be reflected and its insertion examined. Clean and study the following : Bursae. (Vide Spalteholz, Figs. 385, 386.) (a) Bursa trochanterica M. glutaei maximi. (b) Bursa ischiadica M. glutaei maximi. (c) Bursae glutaeofemorales. Muscles. (a) Gluteus medius muscle (M. glutaeus medius). (b) Piriform muscle (M. piriformis). Note the relation it bears to the foramen ischiadicum ma jus. (c) Tendon of obturator internus muscle (M. obturator internus), pass- ing through the foramen ischiadicum minus and having the Mm. gemelli superior and inferior above and below it. (d) Quadratus femoris muscle (M. quadratus femoris). (e) Smallest adductor muscle (M. adductor minimus) (0. T. upper adductor magnus). (/) Tendon of the obturator externus muscle (M. obturator externus). Blood-vessels. (Fig. 48.) (a) Above the M. piriformis: (aa) Superior gluteal artery (A. glutaea superior}. (aaa) Upper ramus (ramus superior). (aab) Lower ramus (ramus inferior). (ab) Superior gluteal veins (Vv. glutaeae superior -es). (b) Below the M. piriformis: (ba) Inferior gluteal artery (A. glutaea inferior) (0. T. sciatic artery). (baa) Coccygeal branch, passing inward between the greater and lesser sacrosciatic ligaments to reach the integument and fascia in the region of the coccyx. Some twigs derived from this have already been cut in reflecting the muscle. (bab) Companion artery of the great sciatic nerve (A. comitans N. ischiadici). (bac) Artery to the quadratus femoris. This artery will serve as a guide for the nerve to this muscle in the further dissection. (bb) Inferior gluteal veins (Vv. glutaeae inf eriores). (be) Internal pudendal artery (A. pudenda interna). The pudic vessels can be seen emerging from the pelvis through the foramen ischiadicum ma jus and immediately re-enter- ing through the foramen ischiadicum minus. No DISSECTION OF THE LOWER EXTREMITY 127 branches of these vessels are found at this stage of the dissection. What is the canal of Alcock? (bd) Terminal branches of the medial circumflex artery (A. cir- cumflexa femoris medialis). What is the "crucial anas- tomosis" ? FIG. 48. A. glutaea superior A. perforans prima r Arteries of the gluteal region. The Mm. glutaeus max. and med. are, in great part, removed. (After Gegenbaur, Lehrb. der Anat. des Mensch., Leipzig, 1899, 7 Aufl., Bd. il. p. 285, Fig. 545.) Nerves. (Fig. 49.) (a) Above the M. piriformis: (aa) Superior gluteal nerve (N. glutaeus superior}. (b) Below the M. piriformis: (ba) Great sciatic nerve (TV. ischiadicus) . This nerve often divides into two branches (N. peronaeus communis and N. tibialis) over the piriformis muscle. The nerve sup- plying the M. obturator internus and M. gemellus su- perior will be found lying just lateral to the pudic vessels. It rests upon the base of the spina ischiadica. To expose the nerve to the quadratus femoris and gemel- lus inferior, reflect the gemelli muscles under which it runs. When traced as far as the gemellus inferior exer- cise great care and avoid injury to the twig passing into 128 LABORATORY MANUAL OF HUMAN ANATOMY this muscle. The quadratus femoris may now be reflected by detaching it from the femur and turning it towards the ischial tuberosity. The nerves supplying these mus- cles are derived from the tibial nerve (N. tibialis), a branch of the N. ischiadicus. FIG. 49. M. glutaeus max._ N. glutaeus sup. --| — ^ 9 \ Lig. sacrotuberosum- - N. pudendus Ramus perineal, N. cut. fern. post. — M. glutaeus min. - -- M. tensor fasc. lat. M. piriformis N. ischiadicus - M. quad. fern. — -M. glutaeus max. N. cut. fern, post Nerves of the gluteal region (after Hirschfeld, simplified). (From Poirier et Charpy, Trait6 d'Anat. hum., Paris, 1899, t. iii. p. 1111, Fig. 580.) (bb) Posterior cutaneous nerve of thigh (N. cutaneus femoris posterior] (0. T. small sciatic). (bba) Inferior nerves of buttock (Nn. clunium infe- r iores ) . (bbb) Perineal branches (rami perineales). (be) Pudendal nerve (N. pudendus) (0. T. internal pudic nerve). (bd) Inferior gluteal nerve (N. glutaeus inferior). Mm. Glutaei Medius et Minimus and Adjacent Structures. The M. glutaeus medius should be reflected after a careful study has been made of the preceding structures. Eotate the DISSECTION OF THE LOWER EXTREMITY 129 thigh lateralward. Pull the M. glutaeus maximus well outward and divide its aponeurosis of insertion downward for a distance of five to seven centimetres. Grasping the cut edge of the fascia lata just separated from the M. glutaeus maximus, pull it out- ward and dissect in the interval between it and the M. glutaeus medius. By traction upon this band the deep surface of the tensor muscle of the fascia lata (M. tensor fasciae latae) (0. T. tensor vaginae femoris) may be exposed. It is covered by a layer of fascia. The student should now find— (a) Terminal branch of superior gluteal nerve, piercing the anterior bor- der of the M. glutaeus minimus and entering the M. tensor fasciae latae. (b) Ascending branch of lateral circumflex artery (ramus ascendens A. circumflexae femoris lateralis). Separate the M. glutaeus medius from the M. glutaeus mini- mus by passing the fingers between their posterior borders. When completely isolated, divide the M. glutaeus medius five centimetres above the trochanter major and reflect the two parts upward and downward respectively. Carefully preserve the vessels and nerves between the two muscles and clean them thor- oughly. What vessels and nerves are exposed? Trace each to its termination. Can you find— (a) Bursa trochanterica M. glutaei medii posterior? (b) Bursa trochanterica M. glutaei medii anterior? Where is the bursa M. piriformis? Detach the M. glutaeus minimus from its origin and reflect it downward. Observe the capsular ligament of the hip-joint (cap- sula articularis) . Where is the bursa trochanterica M. glutaei minimi ? Find the reflected head of the M. rectus femoris. What is the action of the muscles supplied by the superior gluteal nerve I POPLITEAL SPACE (FOSSA POPLITEA). Before beginning the dissection, review the surface anatomy of this space, noting— (a) Lateral hamstring, formed by the biceps muscle. (b) Medial hamstring, formed by the tendons of the semitendinosus and semimembranosus muscles. (c) Tendon of adductor magnus muscle. Can you trace it as far down- ward as the adductor tubercle1? In what position of the leg can this tendon be outlined most easily? 130 LABORATORY MANUAL OF HUMAN ANATOMY (d) Epicondyles of femur. Which is the more prominent? (e) Line of the knee-joint. Flex and extend the leg to render this study easier. (/) Head of fibula (capitulum fibulae). Determine its relation to the tibia and femur. (g) Position of common peroneal nerve (TV. peronaeus communis). What relation does it bear to the lateral hamstring muscle1? Skin and Superficial Fascia. Make an incision in the middle line of the posterior surface of the thigh through the popliteal fossa from a point ten or twelve centimetres above the bend of the knee to a point ten centimetres below it. Two transverse incisions should next be made, one at each end of the vertical incision, and the flaps formed reflected medialward and lateralward respectively. (See Figs. 3 and 52.) Make the parts tense by means of a large block placed under the knee. Note the general characteristics of the superficial fascia. Re- move this fascia piecemeal, examining the following : (a) Twigs of posterior cutaneous nerve of thigh (N. cutaneus femoris posterior) (0. T. small sciatic). In what part of this space does the terminal branch of this nerve pierce the deep fascia? (b) Small saphenous vein (V. saphena parva). Preserve intact this vein and any of its radicles that you may find. What is the femoro- popliteal vein (V. femoropoplitea) ? (Vide Spalteholz, Fig. 509.) (c) Superficial lymphatic vessels (vasa lymphatica superficialia) . (Vide Fig. 50.) Boundaries of Fossa Poplitea. The fossa poplitea is diamond-shaped. Its roof is formed by the deep fascia (fascia cruris), sometimes called the " popliteal fascia. " Note carefully the density of this fascia. After the fascia has been studied, incise it in the median line and reflect each way. Care should be exercised to avoid injuring the com- municating fibular nerve (N. communicans peronaeus) and a bursa situated between the M. semimembranosus and the medial head of the M. gastrocnemius. Next study the lateral boundaries : (a) Biceps muscle (M. biceps femoris). (b) Semitendinosus muscle (M. semitendinosus) . (c) Semimembranosus muscle (M. semimembranosus). (d) Gastrocnemius muscle (M. gastrocnemius). (da) Lateral head (caput laterale). (db) Medial head (caput mediale). (e) Plantaris muscle (M. plantaris). DISSECTION OF THE LOWER EXTREMITY 131 FIG. 50. Scrotum Lymphoglandulae popliteae , f_Vas lymphaticum profundum F-. Fossa poplitca V. saphena parva The superficial lymphatic vessels of the posterior side of the lower extremity and the deep lymphatics of the popliteal space. (After Toldt, Anat. Atlas, Wien, 1900, 2 Aufl., p. 709, Fig. 1091.) 132 LABORATORY MANUAL OF HUMAN ANATOMY The exposed parts of each of these muscles should be care- fully cleaned. Eemove the fat of the fossa, carefully dissecting out its con- tents (vide infra). In cleaning the structures in the fossa, avoid disturbing their relations. FIG. 51. Tend. M. quadriceps fern. Patella Fascia lata .Strat. synoviale M. quadriceps fern. Lig. patell. prop. med. . % Femur...- M. quadriceps fern, et M. tensor fasciae latae Condyl. med.... M. gracilis— -• N. saphenamag..-' M. sartorius Cap. art. over the cond. med. M. semimemb. M. semitend. i M. gastroc. (caput med.) - Cond. lat. Cap. art. over the cond. lat. ••„ M. gastroc. (caput lat.) . M. biceps fern. N. peronaeus com. N. tibialis • V. poplitea A. poplitea Lymphogland. poplit. Cross-section of the articulatio genu, passing through the middle of the patella. Right side, seg- ment distal to the line of section (P. Fredet). (From Poirier et Charpy, Traite d'Anat. hum., Paris, 1901, 2 ed., t. ii. p. 242, Fig. 180.) Contents of Fossa Poplitea. (Figs. 51-53.) Nerves. (Figs. 51 and 52.) (a) Tibial nerve (N. tibialis) (0. T. internal popliteal nerve). What is its position in the fossa? (aa) Muscular branches (rami muscular es). Dissect each mus- cular branch out carefully and trace into the muscle. (db) Articular branch (ramus articularis) . (ac) Medial cutaneous nerve of the calf (N. cutaneus surae medialis) (0. T. nervus communicans tibialis). Interosseous nerve of the leg (N. interosseus cruris). DISSECTION OF T1IK LOWER EXTREMITY 133 (b) Common peroneal nerve (N. peronaeus communis) (0. T. external popliteal). (ba) Muscular branches (rami musculares). (bb) Lateral cutaneous nerve of calf (N. cutaneus surae lat- er alls}. (be) Peroneal anastomotic branch (ramus anastomoticus pero- naeus) (0. T. nervus communicans fibularis). (c) Posterior cutaneous nerve of thigh (N. cutaneus femoris posterior) (0. T. small sciatic nerve). This nerve is found directly under- neath the fascia. Its branches have already been referred to. (d) A branch of the obturator nerve (N. obturatorius) descends into the space in close relation to the artery. FIG. 52. M. adductor magnus N. tibialis Ramns muscularis M. semimembranosus M. semitendiuosus A. poplitea V. poplitea M. vastus medialis A. genu sup. med. Fossa poplitea Twig to the A. poplitea A. suralis medialis Kami musculares Ramus articularis A. genu inf. med. M. gastrocneralus (caput mediale) M. soleus Tendon of the M. plantaris N. cut. snrae med. M. popliteus M. bicipitis femoris Caput longum Caput breve N. peronaeus mm- munis Ramus artieularis for the knee-joint Ramus muscularis A. genu sup. lat. N. cut. surae lat. A. genu nit-din. M. plantaris A. suralis lateralis . peronaeus communis A. genu inf. lat. •riK-in'iiiius f caput laterale) Arcus tendincus M. -«>l«'i Ramus anast. peronaeus N. suralis The popliteal spare. (After Toldt, Anat. Atlas, Wien, 1900, 2 Aufl., p. 631, Fig. 1010, and (3 lAufl ) p. 842, Fig. 1278, and Cunningham, Manual of Prac. Anat., Phila., 1903, 3d ed., vol. i. p. 1 - 1. H Arteries. (Figs. 52 and 53.) (a) Popliteal artery (A. poplitea). Note especially the n-latu this artery bears to the structures contained in the sj >:»<•« 134 LABORATORY MANUAL OF HUMAN ANATOMY and dissect out its branches. Determine accurately the vessels which enter into the anastomosis about the knee. (aa) Lateral superior artery of knee (A. genu superior lateralis) (0. T. superior external articular artery). (ab) Medial superior artery of knee (A. genu superior medialis) (0. T. superior internal articular artery). (ac) Middle artery of knee (A. genu media) (0. T. azygos ar- ticular artery). (ad) Lateral inferior artery of knee (A. genu inferior lateralis) (0. T. inferior external articular artery). (ae) Medial inferior artery of knee (A. genu inferior medialis) (0. T. inferior internal articular artery). (af) Sural arteries (Aa. surales). What is the rete articular e genu? What is the rete patellae? FIG. 53. A. genu sup. med. A. genu inf. med. Art. nutric. tib.---- A, rec. tib. med ' A. tib. post. _A. recurrens tib. post. _A. tibialis post. A. peronaeus Schema of the A, poplitea, (From Poirier et Charpy, Traite d'Anat. hum., Paris, 1901, 2 eel., t. ii. p. 830, Fig. 448.) Veins. (a) Popliteal veins (Vv. popliteae). (aa) Small saphenous vein (V. saphena parva). (ab) Articular veins of knee (Vv. articulares genu). (ac) Lateral companion vein (V. comitans lateralis). (ad) Medial companion vein (V. comitans medialis). DISSECTION OF THE LOWER EXTREMITY 135 Note especially the relation of the vein to the artery in the upper and lower parts of the fossa. Incise the vein longitudinally and search for valves. Are any present? Lymphatics. (Vide Fig. 50.) (a) Popliteal lymph-nodes (lymphoglandulae popliteae). How many do you find? (b) Deep lymphatic vessels (vasa lymphatica profunda). Study in the floor of the fossa— (a) Popliteal surface (planum popliteum) of the femur. (b) Posterior ligament (ligamentum popliteum obliquum) of the knee- joint. (c) Strong fascia covering popliteal muscle. From what muscle is this fascia derived? A careful drawing of the boundaries and contents of this fossa should now be made. Each structure should be shown in its proper relation and carefully labelled. To complete the study make use of cross-sections. Make a drawing of a section through the middle of the space, labelling each structure found and giving correct relations. POSTERIOR SURFACE OF THIGH (FACIE S FE MORIS POSTERIOR). Make a vertical incision through the belt of skin remaining in the middle of the thigh. Reflect the flaps thus formed lateral- ward and medialward respectively. Superficial Fascia and Cutaneous Nerves. Note carefully branches of arteries and radicles of veins. Preserve these as carefully as possible and trace back the larger vessels. Study the cutaneous nerves in the superficial fascia. Consult Fig. 47, p. 124. (a) Branches of the posterior cutaneous nerve of the thigh (N. cutaneus femoris posterior) (0. T. small sciatic). (b) On the lateral surface of the thigh, passing backward, branches the lateral cutaneous nerve of the thigh (N. cutaneus femon* lat- eralis) (0. T. external cutaneous). (c) On the inner aspect of the thigh, near the knee, the cutaneous branc of the obturator nerve (ramus cutaneus nervi obturatoris) ; als twigs from the rami cutanei anteriores nervi femoralis. Deep Fascia (Fascia lata). (" Broad Fascia.") Clean away carefully and completely the superficial fascia and expose the deep layer of fascia. Note especially its 136 LABORATORY MANUAL OF HUMAN ANATOMY ness at different levels. The deep fascia may next be removed. Follow the rule already given for removal of fascia. Avoid the nervus cutaneus femoris posterior in the median line. Muscles of Back of Thigh. Note carefully the form, position, origin, insertion, action, and nerve supply of each of the following : (a) Biceps muscle of thigh (M. biceps femoris). (aa) Long head (caput longum). (ab) Short head (caput breve). (b) Semitendinosus muscle (M. semitendinosus) . (c) Semimembranosus muscle (M. semimembranosus). What do you understand by the hamstring muscles ? Nerves of Back of Thigh. (a) Posterior cutaneous nerve of thigh (N. cutaneus femoris posterior) (0. T. small sciatic). This nerve will be found directly underneath the deep fascia in the median line of the thigh. (b) Great sciatic nerve (N. ischiadicus] . Note the level at which this nerve divides into the N. tibialis and the N. peronaeus communis. What are the muscular branches (rami musculares) of the nerve and to what muscles are they distributed'? What is the relation of the N. peronaeus communis to the biceps muscle? Is there a triangle formed by the hamstring muscles in which you can readily find the N. ischiadicus? Blood-vessels and Lymphatics of Back of Thigh. The following arteries and accompanying veins will be seen piercing the large muscle inserted into the linea aspera. What muscle is this ? Arteries. (a) First perforating artery (A. perforans prima). (b) Second perforating artery (A. perforans secunda). (c) Third perforating artery (A. perforans tertia). Determine from which of these arteries the superior nutrient artery of the femur (A. nutricia femoris superior) and the infe- rior nutrient artery of the femur (A. nutricia femoris inferior) are derived. Clean each artery and trace it back to the muscle which it pierces. Dissect out the fibrous passage-way through which each artery passes. Note that these openings are in the same line with and exactly analogous to the one through which the terminal portion of the deep femoral artery (A. prof undo, femoris) passes to the back of the thigh. The terminal part of this artery is sometimes called the " fourth perforating artery." What is the purpose of these fibrous arches ? DISSECTION OF THE LOWER EXTREMITY 137 Veins. (a) First perforating vein (V. perforans prima). (b) Second perforating vein (V. perforans secunda). (c) Femoropopliteal vein (V. femoropoplitea). Into what larger vein does each empty? FIG. 54. A. epigastrica superf. .. A. cireumflexa ilium superf. -• A. cireumflexa fern, lat Ramus desc. A. circ. fern, lat V Aa. pudendae ext. -.-.A. cireumflexa med. £ JA. prof, femoris . perforans prima A. genu sup. lat. ?-.-.. A. perforans secunda 3 jJ-A. perforans tertia A. genu suprema .'. A. genu sup. med. Schema of the arteria femoralis. (From Poirier et Charpy Traite d' Anat. hum., Paris. 1901. 2 ed.. t. ii. p. 818, Fig. 4/1.) Paris, 1901, 2 ed., t. ii. p. Determine accurately the course of each of the preceding arteries and veins. What is their relation to the M. vastus lateralis 138 LABORATORY MANUAL OF HUMAN ANATOMY Lymphatics. (Fig. 50.) Do you find any lymphatic vessels ? If so, determine their course and distribution. Are any lymph-nodes (lymphoglandulae} to be found in this region? Great Adductor Muscle (M. adductor magnus). After having completed the dissection of the popliteal sur- face, divide the conjoined tendon of the M. semitendinosus and M. biceps, exposing the origin of the M. semimembranosus. After studying the origin of this muscle and charting the length and breadth of its origin, reflect it downward. Determine accurately the relation of the M. adductor magnus to the linea aspera. What is the adductor tubercle? The form, position, origin, insertion, action, and innervation of the great adductor muscle can best be studied later. Anastomosis upon the Back of the Thigh. (Fig. 54.) What vessels enter into the formation of this anastomosis? How would the circulation to the leg be carried on if the common femoral artery were ligated? Where may the femoral artery be ligated most advantageously, and with the greatest possi- bility of the establishment of a collateral circulation? ANTERIOR SURFACE OF THIGH (FACIES FEMORIS ANTERIOR). Skin and Superficial Fascia of Upper Part of Anterior Surface of Thigh. Make the following incisions : (a) From the spina anterior superior along the line of the inguinal liga- ment of Poupart to the symphysis pubis. (b) From the medial extremity of (a) downward, just lateral from the scrotum and along the medial surface of the thigh for a distance of ten centimetres. (c) From the lower extremity of (b) transversely lateralward over the anterior surface of the thigh to its lateral aspect. Raise the quadrilateral flap thus outlined, taking no fat of the superficial fascia with it. In the superficial fascia of the lower part of the anterior abdominal wall two layers are demonstrable, — (1) more super- ficial (Camper's fascia), fatty, continuous with the fatty super- ficial fascia of the thigh; and (2) a deeper layer (Scarpa's fascia), devoid of fat, inserted into the fascia lata a little below Poupart 's ligament. Study this fascia in conjunction with the DISSECTION OF THE LOWER EXTREMITY 139 FIG. 55. Lig. inguinale [Pouparti] Lymphoglamlnlae inguiiuiles A. i'emoralis V. femoralis Margo falciform is Lymphoglandulae subinguinale; superticiales V. saphena magna _ inguinal and adjacent regions. < After T»Mt, Aimt. Atlas, , 1900, 2 Aufl., p. 706, Fig. 1088.) 140 LABORATORY MANUAL OF HUMAN ANATOMY dissector of the abdomen. What bearing have the attachments of Scarpa's fascia upon the distribution of extravasated urine? Dissect out and study carefully in the superficial fascia the following structures : Veins. (a) Large saphenous vein (V. saphena magna) (0. T. internal saphe- nous). (aa) Accessory saphenous vein (V. saphena accessoria), incon- stant. (b) Superficial epigastric vein (V. epigastrica superficialis). (c) Superficial circumflex iliac vein (V. circumftexa ilium superficialis}. (d) External pudendal veins (Vv. pudendae externae}. Arteries. (a) Superficial epigastric artery (A. epigastrica superficialis}. (b) Superficial circumflex iliac artery (A. circumflexa ilium super- ficialis}. (c} External pudendal arteries (Aa. pudendae externae) (0. T. super- ficial and deep external pudic arteries). (d} Inguinal rami of femoral artery (rami inguinales A. femoralis}. Lymphatics. (Fig. 55.) (a) Inguinal lymph-glands (lymphoglandulae inguinales}. Whence do they draw lymph? Whither does the lymph go from them? (6) Superficial subinguinal lymph-glands (lymphoglandulae subingui- nales superftciales) . Whence do they draw lymph? Whither does lymph go from them? Nerves. (See Fig. 56, p. 143.) Avoid injury to the N. ilio-inguinalis, N. spermaticus externus, N. lumbo-inguinalis, and N. cutaneus femoris lateralis. These nerves are to be studied thoroughly a little later, when the rest of the skin on the anterior surface of the thigh is removed. Oval Fossa of Thigh (Fossa ovalis) (O. T. Saphenous Opening). The structures to be studied at and about the oval opening include— (a) Falciform margin (mar go falciformis}. (aa) Superior cornu (cornu superius). (ab) Inferior cornu (cornu inferius). (b) Covering of cribriform fascia (fascia cribrosa). (c) Junction of V. saphena magna with V. femoralis. (d) Lymph-glands. Remove with great care the superficial fascia of the region, beginning over the upper part of the M. adductor longus and M. pectineus, cleaning the deep fascia (fascia lata) lying beneath. Note that the latter is attached above to the posterior margin of DISSECTION OF THE LOWER EXTREMITY 141 Poupart's ligament. Following this portion of the fascia, fascia pectinea (0. T. pubic portion of fascia lata), lateralward, it will be seen to pass beneath the femoral vessels so as to line the fossa iliopectinea, becoming continuous lateralward with the fascia iliopectinea. The inferior cornu of the falciform margin is now visible. It belongs to that part of the fascia lata which lies lateral from the fossa ovalis, — viz., the superficial layer of the fascia lata (0. T. iliac portion of fascia lata), — and is inserted medialward into the fascia pectinea or deep layer. Observe the cribriform fascia (fascia cribrosa) closing the aperture of the fossa ovalis. The superficial subinguinal lymph-glands must be removed to display it properly. What vessels pass through this fascia cribrosa? Remove the fascia cribrosa carefully, so that the edge of the margo falciformis and its cornu superius may be clearly defined. The upper horn (cornu superius) (0. T. femoral ligament or Key's ligament or ligament of Allan Burns) consists of two layers, an anterior and a posterior. The anterior layer of the cornu superius is a broad lamina, strength- ened by Scarpa's fascia; it bounds the fossa ovalis above and lies ver- tically between it and Poupart's ligament, to which it is attached. The posterior, thicker layer of the cornu superius extends further upward than the anterior, passes superficial to the femoral vessels medialward and upward, assumes a horizontal position, filling up the acute angle between the medial end of Poupart's ligament and the pecten ossis pubis, and really forming (by fusion with the process of Poupart's ligament to the pecten) the anterior or inferior part of the ligamentum lacunare [Giin- bernati]. The femoral canal will be studied farther on. Beneath the fascia cribrosa within the fossa ovalis observe the deep sub- inguinal lymph-glands (lymphoglandulae subinguinales pro- fundae). Skin and Superficial Fascia of Anterior Surface of Thigh and Knee. Continue the vertical incision on the medial aspect of the thigh distalward as far as the medial condyle of the tibia. Make another incision from the medial condyle of the tibia lateralward across the front of the leg as far as the lateral condyle of the tibia. Eeflect the large flap lateralward, taking no fat with t skin and avoiding injury to nerves and blood-vessels and to tlio subcutaneous praepatellar bursa. In the fat of the superficial fascia dissect out carefully 1 following structures: 142 LABORATORY MANUAL OF HUMAN ANATOMY Veins. (a) Large saphenous vein (V. saphena magna) (0. T. internal saphe- nous vein) and its tributaries. Nerves. (a) Ilio-inguinal nerve (N . ilio-inguinalis] . (b) Lumbo-inguinal branch of genitofemoral nerve (N. lumbo-ingui- nalis N. genitofemoralis) (0. T. crural branch of genitocrural ) . (c) Lateral cutaneous nerve of thigh (N. cutaneus femoris lateralis) (0. T. external cutaneous). Follow this nerve into the sheath formed for it by the fascia lata. People whose occupations require excessive standing or walking (fascia lata tense) sometimes suffer from a severe neuralgia of this nerve, — so-called " meralgia paraesthetica," or " Bernhardt's disturbance of sensibility in the thigh." (d) Branches of femoral nerve (N. femoralis) (0. T. anterior crural). (da) Anterior cutaneous rami (rami cutanei anteriores) (0. T. middle and internal cutaneous). (db) Infrapatellar ramus of saphenous nerve (ramus infra- patellaris N. sapheni) (0. T. patellar branch of long saphenous). Look for it near the cutaneous branch of the A. genu suprema. (dc) Cutaneous ramus of obturator nerve (ramus cutaneus N. obturatorii). Bursa. Subcutaneous praepatellar bursa (bursa praepatellaris subcutanea). Pinch up a bit of tissue in front of the patella with forceps and make a transverse cut into the bursa. Explore with the finger. Deep Fascia of Thigh (Fascia lata). Clean the surface of the fascia lata carefully and examine its attachments above and below. Compare with the description in your systematic text-book. Pay especial attention to the fol- lowing points : (a) Superficial layer of fascia lata and margo falciformis of fossa ovalis (0. T. iliac portion of fascia lata). (b) Deep layer of fascia lata or fascia pectinea (0. T. pubic portion of fascia lata). (c) Cribriform fascia (fascia cribrosa). This is really a thin continuation of (a). (d) Iliotibial band (tractus iliotibialis [Maissiati]). What is its sig- nificance ? (e) White lines corresponding to intermuscular septa in depth. (ea) Lateral intermuscular septum of thigh (septum intermus- cular e [femoris} laterale) (0. T. external intermuscular septum). . (eb) Medial intermuscular septum of thigh (septum intermus- culare [femoris] mediale) (0. T. internal intermuscular septum). DISSECTION OF THE LOWER EXTREMITY 143 FIG. 56. N. cutan. fern. lat. Ramus N. cutan. surae l N. lumbo-inguiimlis iRami cut. ant. N. cut. dors. med... N. cut. dors, intermed... N. cut. dors. lat. N. saphenus N. peronaeus superf. N. per. prof. Cutaneous nerves of the flexor side of the lower extremity (schematic). (From Gegenbaur, I.«-hrb. der Anat. des Mensch., Leipzig, 1899, 7 Aufl., Bd. ii. p. 516, Fig. 669.) 144 LABORATORY MANUAL OF HUMAN ANATOMY Note that these two septa divide the thigh into two great osteofascial compartments, one in front, the other behind. The latter is further subdivided by a layer of fascia, sometimes called the * ' posterior intermuscular septum. ' ' The further dissection will reveal the following contents of these osteofascial compart- ments. (Fig. 57.) FIG. 57. V. femoralis jV. saphenus M. sartorius M. rectus femoris A. femoralis M. adductor longus V. saphena magna Sept u m intcrmusculare ~ (femoris) mediate M.gracilis- A. profunda— femoris M. adductor magnus M. semimeiribranosus M. semitendinosus M. rust it s intermedium M. rastits mcdialis _» M. vast us latcraHs Fascia lata ( Tract us iliotibialis) Septum wtermusculare (femoris ) laterale . perforans isckiadictu J/. bleep* fcmor is (caput longum) Cross-section of right thigh, a little above its middle. Surface distal to the cut. (After Toldt, Anat. Atlas, Wien, 1900, 2 AufL, p. 640, Fig. 1020.) (1) In the anterior osteofascial compartment (in front, between the me- dial and lateral septa) the extensor muscles and the femoral nerve. (2) In the posterior osteofascial compartment (behind, between the medial and lateral septa), — (a) Between the lateral and posterior septa, the flexor muscles and the great sciatic nerve. (b) Between the medial and posterior septa, the adductor muscles and the obturator nerve. Sheath for Femoral Vessels and Femoral Canal. Before proceeding to this dissection, the student should study thoroughly, on a dry preparation of the pelvis with its ligaments, the following : (a) Inguinal ligament of Poupart (Lig. inguinale [Pouparti]}. (b) Lacunar, ligament of Gimbernat (Lig. lacunare [Gimbernati] ). After this, divide the cornu superius of the margo falci- formis of the fossa ovalis and carry the knife lateralward just DISSECTION OF THE LOWER EXTREMITY 145 below Poupart's ligament to within two or two and a half cen- timetres of the spina iliaca anterior superior, so as to sever the attachment of this portion of the fascia lata from the ligament. Reflect the fascia and margo falciformis downward and lateral- ward. Carefully pick out the fat and deep subinguinal lymph- glands immediately subjacent, so as to expose the connective tissue sheath of the femoral vessels. With the handle of the scalpel gently separate the sheath from Poupart's ligament in front and from Gimbernat's ligament medialward from it. What is the shape of the femoral sheath? Note the points where it is perforated by— (a) Lumbo-inguinal branch of genitofemoral nerve. (b) Large saphenous vein. (c) Lymp h- vessels. By a study of the cadaver, the use of models and a systematic text-book of anatomy, ascertain how it is that the anterior wall of the femoral sheath represents the continuation into the thigh of the fascia transversalis of the abdomen, the posterior wall of the sheath the continuation of the fascia iliaca of the abdomen. Next open the femoral sheath by making three parallel and vertical incisions, the first over the femoral artery, the second over the femoral vein, and the third one centimetre medial from the second. The incisions all begin above at the Lig. in- guinale [Pouparti], the medial one being one centimetre long, each of the other two from three to four centimetres long. Note the septa, dividing the sheath into three compartments (Fig. 58)- (a) Lateral compartment. It contains the A. femoralis and the N. lumbo-inguinalis. (b) Middle compartment. It contains the V. femoralis. (c) Medial compartment (femoral canal or canalis femoralis) (0. T. crural canal). It contains a lymph-gland ( Rosenmiiller's lymph-gland), some lymphatic vessels, and loose areolar tissue. Observe that the femoral sheath and its contents completely fill up the lacuna vasorum. How is the lacuna vasorum bounded ? How is the lacuna musculorum bounded? What structures pass through the lacuna musculorum? This latter region will be dis- sected later. Introduce the little finger into the canalis femoralis. long is it ? How is it bounded ? Locate exact position of superior 10 146 LABORATORY MANUAL OF HUMAN ANATOMY aperture, — the so-called " femoral ring" (annulus femoralis) (0. T. crural ring). What is directly medial and what directly lateral from this ring? How is it closed above? Can you find the femoral septum of CJoquet (septum femorale [Cloqueti] ) ? What is meant by femoral hernia? Why should it occur where it does and not elsewhere ? Is it more common in males or in females, and why? What must have been the course of a hernia presenting over the fossa ovalis? In cutting down upon M. obliquus interims FIG. 58. Spina iliaca anterior superior Aponeurosis of the M. obliquus externus abdominis k Fascia transversalis Hj^ Nervus femoralis Fascia iliopectinea Lig. inguinale [Pouparti\ \^ Arteria femoralis \ ^v- X Vagina vasorum Vena femoralis Annulus femoralis Lig. lacunare [Gimbernati] M. rectus ab- dominis Cut edge of th( fascia iliaca M. iliopsoas Eminentia iliopectinea \ Fades symphyseos Fascia transversalis i Falx (aponeurotica) Lig. pubicum [Cooperfj \ inguinalis Annulus inguinalis subcutaneus The lacuna musculorum and the lacuna vasorum of the left side, seen from the internal, medial side. (After Toldt, Anat. Atlas, Wien, 1900, 2 Aufl., p. 374, Fig. 616.) it, what are the various coverings met with? Where is such a hernial sac most subject to constriction? How could such con- striction be relieved by the knife? In cutting Grimbernat's liga- ment, what is to be remembered about the origin of the obturator artery ? Femoral Triangle, or Larger Fossa of Scarpa (Trigonum femorale [Fossa Scarpae major]) (O. T. Scarpa's Triangle). Remove the fascia lata from the anterior aspect of the proxi- mal third of the thigh. Do not disturb the fascia lata farther DISSECTION OF THE LOWER EXTREMITY FIG. 59. 147 A. epigastrica - superficialis M. tensor fasciae latac- N. femoralis - A. femoralis -- V. femoralis--- M. sartorius-- A. profunda femoris--- A.circumflexa|Ram-ascendens-' femoris laterahs|Ram descendens - Cut edge of the lamina superficialis - fasciae latae A. perforans prima A. profunda femoris -- M. vastus medialis — V. femoralis N. saphenus A. femoralis M. rectus femoris --- Rete articulare genu A. spermatica externa •A. circumflexa femoris medialis — Ramus superficialis M. adductor brevis —M. adductor longus M. gracilis ^Anterior wall of the canalis adductorius [Hunteri] -Ramus muscularis - N. saphenue — M. sartor i a .< A. genu suprema --.A. genu superior medialis -.Ramus articularis ^Ramus saphenus The femoral arterv to its entrance into Hunter's canal, and segment of the M. sariorius has been taken away. (After Toldt, Anat. Atlas, * Fig. 1003. ) 148 LABORATORY MANUAL OF HUMAN ANATOMY distalward. The boundaries of the triangle may now be defined and its contents dissected out. Remove the femoral sheath and clean the vessels, nerves, and muscles related to the triangle. How is the femoral triangle bounded above, lateralward, and medialward? How is its floor formed? Among the contents find and study the following, comparing your findings with the descriptions in a systematic text-book. Arteries. (Fig. 59.) (a) Femoral artery (A. femoralis). Study carefully the relations of this artery in different parts of Scarpa's triangle. (aa) Superficial epigastric artery (A. epigastrica superficialis}. (ab) Superficial circumflex iliac artery (A. circumflexa ilium superficialis). (ac) External pudendal arteries (Aa. pudendae externae) (0. T. superficial and deep external pudic arteries). (ad) Inguinal rami (rami inguinales). (ae) Muscular rami (rami musculares) . (af) Deep artery of thigh (A. profunda femoris). (a fa) Medial circumflex artery of thigh (A. circumflexa femoris medialis) (0. T. internal circumflex). (afb) Lateral circumflex artery of thigh (A. circumflexa femoris lateralis) (0. T. external circumflex). (afc) Superficial ramus (ramus superficialis). Veins. (a) Femoral vein (V. femoralis). (aa) Superficial epigastric vein (V. epigastrica superficialis). (ab) Superficial circumflex iliac vein (V. circumflexa ilium superficialis). (ac) Thoraco-epigastric vein (V. thoraco-epigastrica) . (ad) External pudendal veins (Vv. pudendae externae) (0. T. external pudic veins). (ae) Large saphenous vein (V. saphena magna) (0. T. internal saphenous). (af) Deep vein of thigh (V. profunda femoris). (afa) Medial circumflex veins of thigh (Vv. circumflexae femoris mediates) . (afb) Lateral circumflex veins of thigh (Vv. circum- flexae femoris later ales}. Nerves. (a) Lumbo-inguinal nerve (N. lumbo-inguinalis) (0. T. crural branch of genitocrural). (b) Lateral cutaneous nerve of thigh (N. cutaneus femoris lateralis) (0. T. external cutaneous). How much of this nerve is in the triangle? (c) Femoral nerve (N. femoralis) (0. T. anterior crural). What is the relation of the branches of this nerve, given off in this fossa, to the A. circumflexa femoris lateralis1? DISSECTION OF THE LOWER EXTREMITY 149 Sartorius Muscle and Hunter's Adductor Canal (M. sartorius et Canalis adductorius [Hunteri]). (Figs. 59 and 60.) Eemove the fascia lata from the distal two-thirds of the thigh, leaving, however, the iliotibial band on the lateral surface. Clean the M. sartorius carefully, watching for the nerves which are near it or pass through it. Study its form, position, origin, in- sertion, action, and innervation. Whence has it received its name ? What is meant by " Hunter's canal' ' or the " adductor canal" (canalis adductorius [Hunteri]) ! Note that it is the continuation distalward of the lacuna vasorum. How is the V. femoralis A. femoralis I FIG. 60. M. vastus medialis N. saphenus Aponeurotic union between the M. vast us medialis and the J(. adductor magnus (ante- rior u-all of the canalis ad- ductorius) M. sartorin Canalis adductorius _. [Hunteri] V. saphena magna - M. adductor magnus, M. gracilis-' A. perforans III.--- M. semimembranomS'' -~M. rectus femoris M. vastus intermedium ..Fascia lata M. vastus lateralis Septum internutfculare (femoris) laterale '. biceps femoris «'ut breve) x. ttduadtau M. biceps femori* (caput longum) M. semitendinosus Cross-section of the right thigh through Hunter's canal, a little above the opening in the adductor magnus muscle. Surface distal to the section. (After Toldt, Anat. Atlas, Wien, 1900, 2 Aufl., p. 641, Fig. 1021.) canal or tunnel formed? Study the constituents of the walls of the canal. Cut through the fibrous expansion forming the ante- rior wall of the adductor canal and study the contents of the canal. How do the femoral vessels leave the canal to enter the popliteal space? Describe the opening in the M. adductor mag- nus (hiatus tendineus adductorius). At what point do the N. saphenus and the A. genu suprema leave the canal? Study 1 lower part of the A. femoralis and its relations. Examine the following branches: (a) Muscular rami (rami musculares). What muscles are supplied by these? 150 LABORATORY MANUAL OF HUMAN ANATOMY (b) Highest artery of knee (A. genu supremo] (0. T. anastomotica magna). (ba) Saphenous ramus (ramus saphenus). (bb) Muscular ramus (ramus muscularis). (be} Articular rami (rami articular e s) . Review now the femoral vein throughout its whole course, examining its various tributaries. How does its relative position as regards the femoral artery change as it proceeds distalward towards the hiatus tendineus adductorius? With scissors slit the vein open along its whole length and look for valves. The femoral vein is often thrombosed in the course of typhoid fever, or in pelvic infections, especially during the puerperal period (phlegmasia alba dolens). Femoral Nerve and Muscles of Front of Thigh. (Fig. 61.) Clean the muscles of the front of the thigh carefully and follow the nerve branch to each. Study thoroughly the femoral nerve (N. femoralis) (0. T. anterior crural) and all its branches, cutaneous and muscular. What are these and what do they supply? Does the femoral nerve innervate joints! Study the form, position, origin, insertion, action, and inner- vation of each of the following muscles : (a) Tensor muscle of fascia lata (M. tensor fasciae latae) (0. T. tensor vaginae femoris). Study exact relation to — (aa) Iliotibial band (tractus iliotibialis [Maissiati]) . Cut through the iliotibial band below the tensor muscle, deflect it forcibly lateralward, and displace the M. vastus lateralis medialward so as to expose the lateral intermuscu- lar septum (septum inter muscular e [femoris'] laterale). How is it attached at its two edges'? What important structures perforate it? Examine also the medial intermuscular septum (septum inter muscular e [femoris] mediale). Which is the stronger, the medial or the lateral septum? (b) Quadriceps ("four-headed") muscle of thigh (M. quadriceps femo- ris). (ba) Rectus ("straight") muscle of thigh (M. rectus femoris}. (baa) Bursa M. recti femoris. (bb) Vastus lateralis muscle ("lateral great muscle") (M. vastus lateralis) (0. T. vastus externus). (be) Vastus medialis muscle ("medial great muscle") (M. vastus medialis) (0. T. vastus internus). (bd) Vastus intermedius muscle ("intermediate great muscle") (M. vastus intermedius) (0. T. crureus). Cut through the M. rectus femoris at its middle and reflect distal end forcibly. Find the groove between the M. DISSECTION OF THE LOWER EXTREMITY L51 FIG. 61. M. psoas major. M. iliacm — N. femoralis Lig. inguinalc [Pouparti], M. s Superficial branches of the X. femoralis (cut off) M. ten xor fasciae latae — Rami musculares M. ri'ct us femoris- _ (tamed aside) i Ramus articularis Ramus muscularis for the - M. vast us medialis M. vastus lateralis — M. vastus intcrmedius - N. saphenus- Ramus muscularis for the— M. vastus lateralis and for the knee-joint M. vastus medialis — M. rectus femoris _ A. et V. iliaca ejcterna N. obturatorius Proiiinntnriiiin M. i>ictineu8 Li' i. juibocapsulare Opening nf th< caimli* oomraforfiM M. obturator extcrnus Ramus ante- Fascia lata— Patilla Rami musculares M. adductor longus (turned aside) •*«vRami musculares from the ramus i>osterior M. adductor />/>•;•/>• M. ffracilis -- Ramus cutaneus of the N'. obturatorius M. adductor mn. \\ 1903, 3 Aufl., p. 839, Fig. 1275. ) 152 LABORATORY MANUAL OF HUMAN ANATOMY vastus medialis and the M. vastus intermedius and follow it proximalward. Observe the nerve to the M. articularis genu running along the medial margin of the M. vastus intermedius. Cut through the body of the M. vastus me- dialis transversely five centimetres above the patella and reflect it mediahvard. Examine carefully the origin of the M. vastus medialis. (be) Articular muscle of knee (M. articularis genu) (0. T. sub- crureus). Make a vertical incision through the M. vastus intermedius so as to expose the M. articularis genu. What is the relation of the tendon of insertion of the latter muscle to the capsule of the knee-joint? Study the relations of the various constituents of the M. quadriceps femoris to the patella and the ligamentum patellae. Examine the retinacula patellae mediale et later ale. When the patellar tendon is struck during life, what constituents of the M. quadriceps femoris contract most? Try it on yourself at home with the thigh exposed. MEDIAL SURFACE OF THIGH (FACIE 8 MEDIALIS FEMORIS}. Long Adductor Muscle (M. adductor longus). Study its form, position, origin, insertion, action, and inner- vation. Then divide it near its origin and reflect it lateralward. Avoid injury to the ramus anterior of the N. obturatorius. Deep Artery of Thigh (A. profunda femoris) and M. Pectineus. The beginning of this artery and some of its branches have already been studied in the femoral triangle of Scarpa. Sepa- rate the aponeurotic tendon of the M. adductor longus from the M. vastus medialis in front and the M. adductor magnus behind, and study the deeper portions of the deep artery and vein of the thigh (A. and V. profunda femoris). The perforating branches of the artery deserve especial attention (cf. Fig. 54, p. 137) : (a) First perforating artery (A. perforans prima). (aa) Superior nutrient artery of femur (A. nutricia femoris superior). (b) Second perforating artery (A. perforans secunda). (c) Third perforating artery (A. perforans tertia). (ca) Inferior nutrient artery of femur (A. nutricia femoris infe- rior). DISSECTION OF THE LOWER EXTREMITY 153 The pectineus muscle (M. pectineus) should now be carefully studied. Ascertain its exact form, position, origin, insertion, action, and innervation. Note that it is covered by the fascia pectinea (0. T. pubic portion of fascia lata). Observe the bursa M. pectinei. Short Adductor Muscle (M. adductor brevis), Medial Circumflex Artery, and Obturator Nerve. Cut through the M. pectineus at its origin and reflect it distal- ward and lateralward. Avoid injury to the ramus anterior of the N. obturatorius. Is an accessory obturator nerve present? Dissect out the branches of the medial circumflex artery (A. cir- cumflexa femoris medialis) in this region and review the artery as a whole. Follow especially— (a) Superficial ramus (ramus super ficialis). (b) Deep ramus (ramus profundus). (c) Acetabular ramus (ramus acetabuli). Clean the short adductor muscle (M. adductor brevis) and study its form, position, origin, insertion, action, and innerva- tion. Then cut through it at its origin and reflect it distalward and lateralward. Now dissect out the posterior ramus of the ob- turator nerve (N. obturatorius) and study the nerve as a whole. How does it get into the thigh? What muscles receive their motor innervation from it? How do the anterior and posterior rami differ in their relations ? Which sends a branch to the hip- joint? Which to the knee-joint? How is the obturator innerva- tion of the hip and knee of interest in hip-joint disease? Other Muscles on Medial Side of Thigh. Study the form, position, origin, insertion, action, and inner- vation of the following: (a) Gracilis ("slender") muscle (M. gracilis). (aa) Bursa M. sartorii propria. (ab) Bursa anserina. (b) Smallest adductor muscle (M. adductor minimus) (0. T. upper por- tion of adductor magnus). (c) Great adductor muscle (M. adductor magnus). (ca) Hiatus tendineus adductorius (already studied). Observe its double nerve-supply. Detach (b) and (c) at their origins and reflect them. (d) External obturator muscle (M. obturator externus). (e) Psoas major ("larger lumbar") muscle (M. psoas major). (f) Iliac muscle (M. iliacus). The conjoined tendon of (e) and (/) may now be studied. 154 LABORATORY MANUAL OF HUMAN ANATOMY Obturator Artery (A. obturatoria). (Cf. Spalteholz, Fig. 469.) Eeflect the M. obturator externus and in it and beneath it find the following branches of the obturator artery : (a) Anterior ramus (ramus anterior). (b) Posterior ramus (ramus posterior). (ba) Artery of acetabulum (A. acetabuli). HIP- JOINT (ARTICULATIO COXAE}. Cut through the A. femoralis, V. femoralis, and N. femoralis two or three centimetres below Poupart's ligament; tie the dis- FIG. 62. Lig. iliofemorale (fasc. ilio-pretrochanter.) Memb. obturat. Articulatio coxae, anterior view. (From Poirier et Charpy, Traits d'Anat. hum., Paris, 1899, 2 ed., t. i. p. 716, Fig. 721.) tal stumps together and reflect them distalward. Then cut through the M. sartorius and M. rectus femoris five centimetres from their origin and reflect them. Cut away the conjoined tendon of the M. iliacus and M. psoas at its insertion and turn it proximalward. Examine the bursa iliopectinea, the bursa M. DISSECTION OF THE LOWER EXTREMITY 155 recti femoris, and the bursa iliaca subtendinea. Reflect the M. tensor fasciae latae. Clean the outer surface of the hip-joint. The joint is an enarthrosis. What is meant by this? What bony surfaces are concerned! Study the following ligaments (Figs. 62 and 63) : (a) Joint-capsule (capsula articularis). (b) Strengthening ligaments. (ba) Iliofemoral ligament (ligamentum iliofemorale) (0. T. Y- shaped ligament of Bigelow ) . (baa) Superior fasciculus to tubercle in front of great trochanter (Lig. iliofemorale superius). FIG. 63. M. glut, min Caps, articularis _ .M. obt. ext. Frontal section of the articulatio coxae, passing through the fovea capitis femoris (From Poirier et Charpy, Traite d'Anat. hum., Paris, 1899, 2 ed., t. i. p. 7-M, 1' ' (bab) Anterior or inferior fasciculus to tubercle in front of small trochanter (/.///. iliofemorale /////• rin§). This is perhaps the strongest ligament in tho body. It will resist a strain of from two hundred and fifty to seven hundred and fifty pounds. (bb) Ischiocapsular ligament (ligamentum ischiocapsular^ ischiocapsular band). (be) Pubocapsular ligament (ligamentum j.ul.n.apsulan pubocapsular band or pubofemoral l.uamrnt ) (bd) Orbicular zone (zona orhn-nlans) ,O. T. xonular 1 ring ligament). 156 LABORATORY MANUAL OF HUMAN ANATOMY Make the maximal movements in the joint in the direction of (1) extension, (2) flexion, (3) adduction, (4) abduction, (5) rota- tion medialward, (6) rotation lateralward, (7) circumduction. How are the ligaments affected in each instance ? What muscles are concerned in each movement in the living body ? Open the articulation. Eemove the whole capsule first, with the exception of the ligamentum iliof emorale. Test the strength of this and then remove it. Study each of the following ligaments : (a) Glenoid lip (labrum glenoidale] (0. T. cotyloid ligament). (b) Transverse ligament of acetabulum (ligamentum transversum ace- tabuli) . (c) Round ligament of the femur (ligamentum teres femoris). This would be better designated " triangular ligament," or, better still, Lig. intrarticulare coxae, a name suggested by Fick. It is probable that it is a vestige of a pubofemoral muscle the tendon of which has become invaginated into the joint. Study the blood supply and nerve supply of the joint. (Cf. Poirier et Charpy, t. i., Figs. 731 and 732.) Follow the reflec- tions of the synovial membrane. Cut through the ligamentum teres, remove the lower extrem- ity from the trunk, and continue the dissection at a side-table. LEG AND FOOT. Make the following incisions: (1) an incision distalward along the middle line of the leg and dorsum of the foot, in front, extending as far as the base of the middle toe; (2) transverse incisions extending (a) across the ankle and (b) across the bases of the toes. Reflect the flaps thus formed, taking no fat with the skin. Superficial Fascia. Note the characteristics of this fascia and determine with what fasciae it is continuous above and below. Dissect out the following : Veins. (Vide Spalteholz, Figs. 507-509.) (a) Dorsal digital veins of foot (Vv. digitales dor sales pedis}. (b) Intercapitular veins (Vv. int er capitular e s] . (c) Common digital veins of foot (Vv. digitales communes pedis). (d) Dorsal venous arch of foot (arcus venosus dorsalis pedis (cuta- neus)). (e) Dorsal cutaneous venous network of foot (rete venosum dorsale pedis cutaneum). DISSECTION OF THE LOWER EXTREMITY 157 (/) Lateral marginal vein (V. marginalis lateralis). (g) Medial marginal vein (V. marginalis medialis). Trace these veins proximalward and determine their relation to the large saphenous vein (V. saphena magna) and the small saphenous vein (V. saphena parva). Nerves. (See Fig. 56, p. 143.) Refer frequently to charts in the study of cutaneous nerves and determine the exact area of skin supplied by each. (a) Saphenous nerve (N. saphenus). (aa) Medial cutaneous branches of leg (rami cutanei cruris medialis). (b) Branches of lateral cutaneous nerve of calf (N. cutaneus surae). (c) Superficial peroneal nerve (N. peronaeus superficialis) . (d) Terminal twigs of deep peroneal nerve (N. peronaeus profundus). (e) Dorsal digital nerves (Nn. digitales dor sales}. (/) Lateral dorsal cutaneous nerve (N. cutaneus dorsalis lateralis), from the N. tibialis. Carefully remove the superficial fascia, preserving the struct- ures which you have dissected, and expose the deep fascia. Deep Fascia of the Leg (Fascia cruris). (Figs. 64 and 67.) Observe that this fascia is continuous with the fascia lata; note also its shiny, aponeurotic character just below the knee, where it gives origin to muscles. Trace the fascia downward, noting that it tends to become thinner distalward, but is strength- ened just above the ankle to form the transverse ligament of the leg (lig amentum transversum cruris) (0. T. upper or broad part of anterior annular ligament). Note the exact points of attach- ment of the ligament and observe that it sends a septum to the tibia, thus forming two compartments, one medial for the M. tibialis anterior, one lateral for the M. extensor longus hallucis and M. extensor longus digitorum. The fascia cruris becomes continuous below with the dorsal fascia of the foot (faxrin dorsalis pedis), the latter being continuous at the sides of the foot with the plantar aponeurosis (aponeurosis plantar is). In the fascia dorsalis pedis examine the Lig. cruciatum cruris (0. T. lower part of anterior annular ligament). Determine the exact attachments of the two limbs of the Y of this ligament, and their relations to the tendons of the muscles over which they pass. A good description is given in Spalteholz's Atlas, p. 356. Observe the band passing from the lateral malleolus to the pofl terior prominence of the os calcis; this is the retinaculun Mm. peronaeorum superius (0. T. external annular ligament). (Fig. 67.) 158 LABORATORY MANUAL OF HUMAN ANATOMY Incise now the deep fascia longitudinally, midway between the tibia and fibula, but do not cut through the Lig. transversum cruris or the Lig. cruciatum cruris. Note that the fascia becomes continuous medialward with the periosteum of the tibia, and that lateralward it sends a septum into the crista anterior of the fibula, forming the anterior [fibular] intermuscular septum (sep- tum intermusculare anterius [fibulare]) (0. T. anterior peroneal septum). This latter septum separates the contents of the " anterior tibiofibular compartment" of the leg from the con- tents of the " peroneal compartment." The latter is bounded posteriorly by another septum going into the crista lateralis of FIG. 64. M. tibialis anterior Tibia- V. saphena magna N. saphenus^ M. flexor digitorum longus^ M. tibialis posterior, A. tibialis posterior. N. tibialis- M. gastrocnemius— (caput mediate) Tendon of the M. plantaris -- M. soleus-" A", cutaneus surae medialis' Membrana interossea cruris A. tibialis anterior A", peronaeus profundus .!/. tjirnsor digitorum longus Septum intermuscular e anterius (fibulare) ^ — M. extensor hallucis longus _N. peronaeus superficialis ^.M. peronaeus longus -.Septum intermusculare posterius (fibulare) ^-A. peronaea Lamina pr0funda^fasc.ae ,. f cruris Lamina superficiahs) ' Ramus anastomoticus peronaeus saphena parva Cross-section of the right leg a little above its middle. Surface distal to the cut. (After Toldt, Anat. Atlas, Wien, 1900, 2 Aufl., p. 642, Fig. 1023.) the fibula and known as the posterior intermuscular septum (sep- tum intermusculare posterius) (0. T. posterior peroneal sep- tum). It will be studied later. Examine Fig. 64 carefully. Muscles of Anterior Tibiofibular Region. Use cross-sections to complete this study. Study the contents of the anterior tibiofibular osteofascial compartment. Clean carefully each muscle and determine its form, position, origin, insertion, action, and nerve supply. What are flexion and exten- sion of the foot? Study— (a) Anterior tibial muscle (M. tibialis anterior) (0. T. tibialis anticus). (b) Long extensor of digits (M. extensor digitorum longus). DISSECTION OF THE LOWER EXTREMITY FIG. 65. A. genu sup. lat. Patella A. genu infer, lat. .A. recurrens tihialisant. A. tibialis ant. 159 Lig. trans, eruris A. malleolaris ant. lat. A. dorsalis pedis A. arena ta Aa. inrtat.-irseae dorsales Arteries of the anterior part of the leg. The Mm. ext. hnllm-is long, and ext. dig. long, an- drawn aside and the M. ext. dig. hn-vis N divided. (From Gegenbaur, Lehrb. der Anat. dcs Mm-ch.. I 1899, 7 Aufl., Bd. ii. p. 294, Fig. .547.) 160 LABORATORY MANUAL OF HUMAN ANATOMY (c) Long extensor of great toe (M. extensor hallucis longus). (d) Third peroneal muscle (M. peronaeus tertius). Examine the vagina tendinis M. tibialis anterioris, the vagina tendinis M. extensoris hallucis longi, and the vagina tendinum M. extensoris digitorum longi. Arteries of Anterior Tibiofibular Region and Dorsum of Foot. Separate the M. extensor digitorum longus from the M. tibi- alis anterior and expose the following; at the same time dissect out the structures on the dorsum of the foot. (a) Anterior tibial artery (A. tibialis anterior). (Vide Fig. 65, and Spalteholz, Fig. 479.) How does this artery pass to the anterior compartment of the leg, and what is its relation to the membrana interossea cruris? (aa) Posterior recurrent tibial artery (A. recurrens tibialis pos- terior). (ab) Anterior recurrent tibial artery (A recurrens tibialis an- terior). (ac) Lateral anterior malleolar artery ( A. malleolaris anterior lat- eralis) (0. T. external malleolar). (ad) Medial anterior malleolar artery (A. malleolaris anterior medialis) (0. T. internal malleolar). (ae) Medial malleolar network (rete malleolar e mediale). (af) Lateral malleolar network (rete malleolar e laterale). The continuation of the anterior tibial artery from in front of the ankle-joint is known as the — (b) Dorsal artery of the foot (A. dorsalis pedis). (ba) Lateral tarsal artery (A. tarsea lateralis). (bb) Medial tarsal arteries (Aa. tarseae mediales). (be) Arcuate artery (A. arcuata). (bd) Dorsal network of foot (rete dorsale pedis). (be) Dorsal metatarsal arteries (Aa. metatarseae dorsales). (bf) Deep plantar branch (R. plantaris profundus). Nerves of Anterior Region of Leg and Dorsum of Foot. (a) Deep peroneal nerve (N. peronaeus profundus) (0. T. anterior tibial). (aa) Muscular branches (rami muscular es] . (ab) Dorsal digital nerves to lateral surface of hallux and to medial surface of digit II. (Nn. digitales dorsales hallucis lateralis et digiti secundi medialis). Determine how the deep peroneal reaches the anterior surface of the leg. Does it accompany the artery? What area of the skin does it supply? What muscles are supplied by this nerve? (b) Superficial peroneal nerve (N. peronaeus superficialis) (0. T. mus- culocutaneous). (ba) Muscular branches (rami muscular es). (bb) Medial dorsal cutaneous nerve (N. cutaneus dorsalis me- dialis). DISSECTION OF THE LOWER EXTREMITY 161 (be) Intermediate dorsal cutaneous nerve (N. cutaneus dorsali* intermedius). (bd) Dorsal digital nerves of the foot (Nn. digitales dorsales pedis ) . The proximal part of the N. peronaeus superficial will be studied later. FIG. 66. N. peronaeus com.. V \ N. et M. peronaea long. M-, ..N. peronaeus prof. M. tibialis ant. N. peronaeus superf. M. ext. dig. long. . .. .._ M. ext. hallucis long. N. suralis.,... M. peronaeus prof. Nn peronaei superficialis et prof undus (after Hirschfeld). (From Poirier et Charpy, Traite d'Anat. hum., Paris, 1899, t. iii. p. 1125, Fig. 584.) Muscles of Dorsum of Foot. Dissect these out carefully, studying the form posit ion, origin, insertion, action, and innervation of each. 67 and Spalteholz, Fig. 402.) 162 LABORATORY MANUAL OF HUMAN ANATOMY FIG. 67. M. peronaeus tertius — Vagina tendinum — , Mm. peronaeorum commums Rctinaculum Mm. — peronaeorum superius Retinaculum- Mm. peronae- orum inferius M. extensor digitorum brevis M. abductor digit! quinti Vagina tendinis M. tibialis antmoris Vagina tendinum M. extensor-is digitorum pedis longi Vagina tendinis M. extensor is hallucis longi _ M. extensor hallucis brevis M. opponens digiti quinti The muscles on the dorsum and lateral side of the foot. The sheaths of the tendons on the dorsum pedis and in the lateral retromalleolar region have been injected with strong alcohol. (After Toldt, Anat. Atlas, Wien, 1900, 2 Aufl., p. 356, Fig. 597.) DISSECTION OF THE LOWKK KXTKKM1TY 163 (a) Short extensor of great toe (M. extensor hallucis brevis). (b) Short extensor of digits (M. extensor digitorum brevis). Determine the relation of these muscles to the tendons of the long extensor of the digits. What is their action? Have they homologues in the hand? (c) Dorsal interosseous muscles (Mm. inter ossei dor sales). Compare these with similar muscles found in the hand, as regards origin, insertion, action, etc. Where are the bursae intermetatarsophalangeae situated? LATERAL OR PERONEAL REGION OF LEG (RE GIG CRURIS LATERALI8). The superficial fascia of this region has already been studied. An anterior intermuscular septum (septum inter muscular e ante- rius [fibulare] ) has been found passing from the deep fascia into the crista anterior fibulae. Incise the deep fascia longitudinally in this region ; reflect it posteriorly and note the corresponding posterior [fibular] intermuscular septum (septum intermuscu- lar e posterius [fibulare] ) going to the crista lateralis fibulae. A lateral or peroneal osteofascial compartment is thus formed. Dissect its contents and supplement the dissection by the use of cross-sections made at different levels ; note carefully the altera- tions in the relations of the different contents of the compart- ment at different levels. Study the following : Peroneal Muscles and Retinacula. Clean each muscle carefully, defining well its borders and noting the form, position, origin, insertion, action, and innerva- tion of each. (a) Long peroneal muscle (M. peronaeus longus). What action does this muscle have as regards the arch of the foot? (b) Short peroneal muscle (M. peronaeus brevis). Trace the tendons of both muscles distalward into the foot. What are their relative positions in the fossa retromalleolaris lateralis? (Cf. Fig. 68.) What is the trochlear process (j,n- cessus trochlearis) of the os calcis? Examine the bony foot and determine the position of the peroneal sulcus (sulcti* M. peronai '> [longi]). Define next the retaining bands of the peroneal muscles macula}. (Cf. Spalteholz's Atlas, Fig. 409.) 164 LABORATORY MANUAL OF HUMAN ANATOMY (a) Eetinaculum Mm. peronaeorum superius (0. T. external annular ligament). (b) Eetina^ulum Mm. peronaeorum inferius. What is the relation of the latter to the ligamentum cruciatum cruris? (See Fig. 67.) Dissect out carefully the common synovial sheath of the pero- neal muscles (vagina tendinum Mm. peronaeorum communis). FIG. 68. M. tibialis ant. A. et V. tibial. ant. and N. peronaeus prof. M. ext. hal. long. N. saphenus et V. saphena M. tibial. post- M. flex. dig. long. A. tibial. post.' N. tiabialis/. M. plantar ^ „ M. ext. dig. long. //// " - M. peronaeus long. v M. peronaeus brev. V. saphena parva M. flex. hal. long. ( M. triceps surae N. suralis Cross-section passing through the inferior part of the leg. Right side, segment distal to the line of section. Anterolateral region (lighter shade).— The two groups, anterior and lateral, are plainly separated. The M. tiabialis ant. has become tendinous and accompanies the A. tibialis ant. The fleshy fibres of the M. peronaeus long, have disappeared. The M. peronaeus brev. is attached to the corresponding surface of the fibula. The N. peronaeus superf. has emerged from between the two muscles, but runs beneath the fascia cruris, which it is about to perforate. Posterior region (darker shade).— There is to be noted a displacement of the muscles. The M. tibialis post, has left the space between the flexors and, gaining the medial aspect of the leg, passes beneath the tendon of the M. flex. dig. long. Superficial layer (intermediate shade).— The tendo calcaneus [Achillis] receives the lowest fibres of the M. soleus. (From Poirier et Charpy, Traite d'Anat. hum., Paris, 1899, 2 ed., t. ii. p. 268, Fig. 196.) What is its extent proximalward and distalward? This sheath may be seen to better advantage if injected. Note here also the subcutaneous bursa over the lateral malleolus (bursa subcutanea malleoli later alis). Peroneal Nerves. Trace the course of the N. peronaeus communis and dissect out all the branches : DISSECTION OF THE LOWER EXTREMITY 165 (a) Common peroneal nerve (N. peronaeus communis) (0. T. external popliteal nerve). (oa) Superficial peroneal nerve (N. peronaeus superficialis) (0. T. musculocutaneous nerve). (ab) Deep peroneal nerve (N. peronaeus profundus) (0. T. ante- rior tibial nerve). What muscles are supplied by the superficial peroneal nerve? What cutaneous area? Review at this stage of the dissection the distribution of the deep peroneal nerve. What are the homo- logues of these nerves in the forearm? MEDIAL REGION OF LEG (REGIO CRURIS ME- DIALIS) (0. T. TIBIAL REGION). The student has but little to examine here, as the tibia is sub- cutaneous. Study— (a) Tendons of insertion of Mm. sartorius, gracilis, and semitendinosus. (b) Great saphenous vein (V. saphena magna) (0. T. internal saphenous vein ) . (c) Branches of saphenous nerve (N. saphenus) (0. T. internal saphe- nous nerve). (ca) Infrapatellar branch (ramus infrapatellaris) . (cb) Medial cutaneous rami of leg (rami cutanei cruris mediales) . (d) Medial inferior artery of knee (A. genu inferior medialis) (0. T. inferior internal articular artery). (e) Tibial collateral ligament of knee-joint (Lig. collateral tibiale) (0. T. internal lateral ligament). POSTERIOR REGION OF LEG AND HEEL (REGIO CRURIS POSTERIOR ET REGIO CALCANEA) (0. T. POSTERIOR TIBIOFIBULAR REGION). Note how the leg tapers from above downward. The large, convex, fleshy upper half is known as the calf (sura). The lower half rapidly diminishes in size, so that the tibia and fibula may be felt as they pass into their respective malleoli. Behind each malleolus will be found a fossa. Flex the foot and extend it and note the play of tendons in each fossa. These fossae become obliterated in pathological processes involving the synovial mem- brane of the ankle-joint. Outline the stronger tendon (tendo calcaneus [Achillis] ) passing down to the os calcaneum. Superficial- Fascia of Leg. Make the muscles of the calf tense and continue the medial 166 LABORATORY MANUAL OF HUMAN ANATOMY incision already made in the dissection of the fossa poplitea down to the heel; at the distal extremity of this make a trans- verse incision extending for five centimetres along the margo pedis lateralis and margo pedis medialis. Eeflect the flaps. Note the general characteristics of this fascia as regards the amount of fat contained, the general direction of its fibres, and the strength of the same. In it, dissect out carefully the fol- lowing : Veins. (Vide Spalteholz, Fig. 509.) (a) Small saphenous vein (vena saphena parva) (0. T. external saphe- nous vein). What is its relation to the malleolus lateralis? Note that it is the continuation of the lateral marginal vein of the foot (vena marginalis lateralis) into the leg. In the upper half of the leg this vein is ensheathed by a duplicature of the fascia cruris. Dissect out the two branches into which it bifurcates above and trace these out into the vena poplitea and the vena femoris profunda. What is the relation of the vena femoro- poplitea to the latter? Trace one of the perforating veins through the fascia cruris. Incise the vein longitudinally and determine whether it has valves or not. (b) Large saphenous vein (V. saphena magna) (0. T. internal saphe- nous). Determine its relation to the malleolus medialis. It is the continuation of the medial marginal vein (vena marginalis medialis) of the foot into the leg. Do you find a collateral vein accompanying it? When present, it will be found just posterior to the large vein. Incise the vein longitudinally and determine the characteristics of its valves. Nerves. (Fig. 69.) (a) Nerve of the calf (N. suralis) (0. T. short saphenous nerve). This nerve is formed by the union of the following: (aa) Medial cutaneous nerve of the calf (N. cutaneus surae medialis). In the greater part of its course this nerve will be found beneath the fascia cruris. At the middle of the leg it pierces this fascia to become subcutaneous. (ab) Anastomotic peroneal branch of the N. cutaneus surae lateralis (ramus anastomoticus peronaeus}. (b) Lateral cutaneous nerve of calf (N. cutaneus surae lateralis) (0. T. nervus communicans fibularis). (c) Posterior cutaneous nerve of thigh (N. cutaneus femoris posterior) (0. T. small sciatic). This nerve will be found beneath the fascia cruris. It sends twigs through the fascia to end in the skin. (d) Medial cutaneous branches (rami cutanei cruris mediales) to the leg from the N. saphenus. Determine the area of skin supplied by each nerve. Eemove the superficial fascia of the leg, and study the deep fascia. DISSECTION OF THE LOWER EXTREMITY 167 FIG. 69. N. tibialis I N. cutaneus femoris posterior^ Ramus cutaneus cruris medialis.-. of the N. saphenus HID [— N. peronaeus rommunte N. cutaneus surae medialis N. cutanuiis sunn- laU-ralis .. V. saphena parra N. cutaneus surae medialis (shining through) I- N. cutaneus surae medialis ._ Ramus anastomoticus peronaeus ._.N. suralis N. cutaneus dorsalis lateralis Kami calcanei laterales /' The cutaneus nerves of the posterior side of the leg. (After Toldt, Anat. Atlas, Wi,n, 1903, SAufl., p. M9, Fig. 1287.) 168 LABORATORY MANUAL OF HUMAN ANATOMY Deep Fascia of Leg (Fascia cruris). This fascia extends from the knee to the malleoli. It repre- sents almost a complete cone, being interrupted only at the f acies medialis of the tibia. What is the relation of its superior cir- cumference to the capitulum fibulae, the condyles of the tibia, and the fascia lata? Its inferior circumference is attached to the malleoli and the tuber calcaneum. Between these three bony projections it becomes continuous with the annular ligaments about the ankle. Examine cross-sections of the leg and note the different relations of the fascial reflections and the osteofascial compart- ments formed by septa passing from this fascia into the tibia and fibula. They have already been referred to above. The septum intermusculare anterius [fibulare] and the septum intermuscu- lare posterius [fibulare] divide the sub fascial space into three compartments. (See Figs. 64 and 68.) (a) Anterior compartment, deep, prismatic in form. It lodges the M. tibialis anterior, the M. extensor digitorum longus, the M. extensor hal- lucis longus, the M. peronaeus tertius, and the anterior tibial vessels and nerves. (b) Lateral compartment: this lodges the peroneal muscles and the superior part of the nervus peronaeus superficialis. (c) Posterior compartment: this is divided into two secondary com- partments by the deep transverse fascia of the leg passing from the margo medialis of the tibia to the crista lateralis of the fibula. Posterior to this fascia will be found the M. triceps surae and the M. plantaris ; anterior to it will be found the M. tibialis posterior, M. flexor digitorum longus, M. flexor hallucis longus, the posterior tibial vessels and nerves, and the peroneal vessels. The fascia cruris varies much in thickness in different regions. It is composed of transverse longitudinal and oblique fibres. The transverse fibres arise from the crista anterior of the tibia and after encircling the leg are inserted upon the margo medialis of the same bone. The oblique and longitudinal fibres arise from the bony projections into which the superior circum- ference of this fascia is attached. What muscles send off proc- esses which reinforce the longitudinal and oblique fibres! Incise the fascia in the median line from the fossa poplitea to the os calcaneum and reflect the flaps. Muscles of the Superficial Posterior Osteofascial Compartment. These may now be dissected out. The muscles of the leg find their homologues in the muscles of the fore- arm. Any differences found are to be explained by the adaptation of the DISSECTION OF THE LOWER EXTREMITY 169 leg muscles to locomotion. The relative atrophy of the motor system of the toes is due to the loss of its femoral attachment and to a displacement of the flexors and extensors, deprived of their tibial and fibular attach- ments, downward into the intrinsic musculature of the foot. The pro- nator and supinator systems are almost absent, being represented by the popliteus alone, and this through skeletal modifications has lost its primi- tive role. The muscles of the leg, like those of the forearm, are delimited into an anterior, a posterior, and a lateral group by the bones of the leg and aponeurotic septa. Study carefully the origin, insertion, form, action, and inner- vation of the following muscles : (a) Triceps muscle of the calf (M. triceps surae). (Vide Spalteholz, Figs. 393-94.) (aa) Gastrocnemius muscle (M. gastrocnemius) . (aaa) Lateral head (caput laterale). Look for a small sesamoid cartilage or bone in this head. Observe the lateral bursa of the gastrocnemius (bursa M. gastrocnemii lateralis) and the bursa bicipitogas- trocnemialis. (aab) Medial head (caput mediale). Observe the medial bursa of the gastrocnemius (bursa M. gastrocnemii medialis) and the bursa M. semimembranosi. Dis- sect this bursa out carefully and determine whether or not it communicates with the joint-cavity. Divide the gastrocnemius transversely near its attachment to the tendo Achillis and reflect it upward, preserving vessels and nerves passing into each head, and study the muscle beneath the M. gastrocnemius. (ab) Soleus muscle (M. soleus). (Vide Spalteholz, Fig. 394.) 'Determine its exact origin from the fibula and tibia. Note that the tendon of this muscle fuses with the tendon of the gastrocnemius to form the— (aba) Tendo calcaneus [Achillis]. Divide the soleus transversely at the level at which it joins the gastrocnemius. Incise the belly of the soleus in the middle line and expose the tendinous arch (arcus tendineus M. solei) and the blood-vessels and nerves entering the muscle. The plantaris muscle may be divided to permit of the turning of the tendo calcaneus [Achillis] downward. Determine its exact attachment to the os calcaneum and study the following bursae : (1) Bursa subcutanea calcanea. (Vide Spalte- holz, Fig. 393.) (2) Bursa tendinis calcanea. (Vide Spalteholz, Fig. 395.) (b) Plantaris muscle (M. plantaris). (Vide SpaKaholz, Ffe. J tendon of this small muscle has already been divided to P«-n 170 LABORATORY MANUAL OF HUMAN ANATOMY the turning of the tendo calcaneus [Achillis] downward. Deter- mine its insertion. It is the homologue of the palmaris longus in the forearm. In monkeys, whose feet are prehensile, it is the proper tensor muscle of the plantar fascia. It is well developed in all plantigrade animals. Deep Transverse Fascia of Leg and Structures beneath it. Note its attachment medially to the tibia and laterally to the fibula. Trace the fascia downward to the ankle, where it becomes thickened to form the ligamentum laciniatum (0. T. internal an- nular ligament). (Vide Spalteholz, Fig. 395.) Incise this fascia longitudinally, leaving the Lig. laciniatum intact, and proceed to the study of the structures beneath it. Muscles. Note carefully the form, position, origin, insertion, action, and innervation of each. (Vide Spalteholz, Fig. 395.) (a) Popliteus muscle (M. popliteus). Determine the relation of its tendon to the capsule of the knee-joint and the ligamentum pop- liteum arcuatum. Note the dense aponeurosis covering this muscle. It receives a strengthening band from the tendon of the semimembranosus muscle. Examine the bursa of the popliteus muscle (bursa M. poplitei}. (Vide Spalteholz, Fig. 396.) Does this bursa communicate with the knee-joint? (b) Long flexor of the digits (M. flexor digitorum longus). (Vide Spalteholz, Fig. 395.) Examine the sheath of the long flexor tendons of the toes (vagina tendinum M. flexoris digitorum pedis longi). This sheath surrounds the tendon as it passes behind the malleolus medialis and is continued well down into the foot. Does it communicate with a sheath which surrounds the tendons of the tibialis posterior and the flexor longus hallucis? (c) Posterior tibial muscle (M. tibialis posterior] (0. T. tibialis pos- ticus). This muscle may be more or less fused with the long flexors, which is only an exaggeration of the normal disposition in man and a reproduction of the normal disposition in the cat. ( Strauss-Diirckheim. ) Examine the sheath of the tendon of the M. tibialis posterior (vagina tendinis M. tibialis posterioris) . (d) Long flexor of the great toe (M. flexor hallucis longus). Examine the sheath of the tendon of the long flexor of the great toe (vagina tendinis M. flexoris hallucis longi). At this stage in the dissection examine the bony leg and foot. Determine the exact position of the sulci through which these tendons pass. Note the exact relation of the tendons beneath the ligamentum laciniatum. (See Fig. 71.) Varieties in the flexor system of the foot are frequent. The tendency to differentiate may be accentuated, but more fre- quently there is a return to the primitive undivided mass arising DISSECTION OF THE LOWER EXTREMITY FIG. 70. 171 A. poplitea ( med. sup. Aa. genu < \- lat. sup. Aa. surah f A. genu inf. lat. A. tibialis ant.^ A. peronaea A. tibialis post.. A. malleolaris post. lat.. A. malleolaris post. med.. Rete calcan.. Arteries of the posterior part of the leg. The muscles of the calf have been removed. The A. peronaea is represented as showing through the muscle lying over it. (From Gegenbaur. Lehrb. der Anat. des Mt,-ii-<-h.. Leipzig, 1899. 7 Aufl.. Bd. ii. p. 295, Fig. 548.) 172 LABORATORY MANUAL OF HUMAN ANATOMY from the tibia and fibula. In the lower forms, such as the rabbit and kangaroo, this primitive undivided mass of flexors is the rule. Arteries. (Vide Fig. 70, and also Spalteholz, Fig. 478.) Trace the popliteal artery downward, and note that it bifurcates just anterior to the arcus tendineus M. solei into the anterior and posterior tibial arteries. The anterior tibial has already been dis- sected. Trace out the course of the posterior tibial artery. Determine the course and position of its linear guide. Where would you take the pulse in the leg and foot? Study — (a) Posterior tibial artery (A. tibialis posterior}. (aa) Fibular branch (ramus fibularis). (ab) Peroneal artery (A. peronaea). (1) Nutrient artery of the fibula (A. nutricia fibulae). (2) Perforating branch (ramus perforans). (3) Communicating branch (ramus communicans) . (4) Lateral posterior malleolar artery (A. malleolaris posterior lateralis). (5) Lateral calcanean branches (rami calcanei later ales). (ac) Nutrient artery of the tibia (A. nutricia tibiae). How are the nutrient arteries of the lower extremities directed ? (ad) Medial posterior malleolar artery (A. malleolaris posterior medialis) (0. T. internal malleolar). (ae) Medial calcanean branches (rami calcanei mediates). (af) Network of heel (rete calcaneum). The terminal branches of the A. tibialis posterior will be found when the dissection of the foot is made. Trace out the veins accompanying this artery and de- termine their anastomoses and the large veins into which they empty. Nerves. (Spalteholz, Fig. 823.) (a) Tibial nerve (N. tibialis). (aa) Muscular branches (rami muscular es). (ab) Interosseous nerve of the leg (N. inter osseus cruris). (ac) Medial cutaneous nerve of the calf (N. cutaneus surae medialis). This nerve has already been dissected. It unites with the ramus anastomoticus peronaeus to form the— (ad) Nerve of the calf (N. suralis). (ada) Lateral calcanean branches (rami calcanei lat- erales). (adb) Lateral dorsal cutaneous nerve of the foot (N. cutaneus dorsalis lateralis pedis). This nerve is the continuation of the N. suralis into the foot. Review at this stage of the dissection the cutaneous nerve supply of the dorsum of the foot. (ae) Medial calcanean branches (rami calcanei mediales) . Dissect out the branch passing into the syndesmosis tibiofibularis. Do you find any branches accompanying the A. tibialis posterior? DISSECTION OF THE LOWER EXTREMITY 173 Make a drawing showing the structures exposed and their exact relations at different levels. Pay especial attention to the relations of the structures in the fossa retromalleolaris medialis. Laciniate (" Fringed") Ligament (Ligamentum laciniatum) (O. T. Internal Annular Ligament). (Fig. 71.) Determine the different points of attachment of this fibrous triangular lamina and the relation that they bear to the malleolus medialis, the medial surface of the tuber calcanei, the medial FIG. 71. M. flexor digit, longus, M. flexor hallucis longus M. tibialis posterior, M. tibialis anterior. Lig. cruciat. crurisy . lai-iniatum I M. flexor hall, brevis Margo pedis medialis, showing the tendons of the muscles of the leg. (From Gegenbaur, Lehrb. der Anat. des Mensch., Leipzig, 1899, 7 Aufl., Bd. i. p. 468, Fig. 340.) plantar aponeurosis, the abductor hallucis muscle, and the fascia cruris. It covers the tendons of the tibialis posterior, the flexor digitorum longus, and the flexor hallucis longus muscles, and the posterior tibial vessels and nerves. Each of these struct im runs within a special sheath. The tibialis posterior and flexor digitorum longus are separated from each other by fibrous septum which passes off from the deep surface of ligament. The fibres constituting the septum pass beneath tendons; one process, ascending, is attached to the 174 LABORATORY MANUAL OF HUMAN ANATOMY medialis and the ligamentum deltoideurn ; the other, descending, is attached to the processus medialis tuberis calcanei. The tendon of the long flexor of the great toe is contained within a special sheath, altogether independent of the ligamen- tum laciniatum. The fibres of this sheath arise from the medial tip of the sulcus M. flexoris hallucis longi and from the summit of the sustentaculum tali. They terminate upon the medial tip of the same sulcus and the medial face of the os calcaneum about one centimetre below the sustentaculum tali. The vessels run above this sheath covered by the ligament, but generally the medial and plantar arteries are separated from each other by a septum. Detach the ligament from the malleolus medialis and dissect it towards the os calcaneum, determining its exact attachment and the position of the septa above mentioned. Make a drawing of these structures at this stage of the dissection. PLANTAR EEGION OF THE FOOT (EEGIO PLAN- TAEIS PEDIS). Before beginning this dissection, review the anatomy of the bones entering into the formation of the foot. Note the number and the exact position of each. (Vide Spalteholz, Figs. 198-99.) Study in the bony foot and upon your subject the following : Arches. (a) Longitudinal arch. This arch extends from the heel to the meta- tarsophalangeal joints. It is capped by the talus and may be divided into — (aa) A posterior limb, formed by the os calcaneum and the pos- terior part of the talus. Note the thickness and the strength of this posterior limb, which serves as a point of attachment for the tendo calcaneus [Achillis]. Study the skeletons of the white, the negro, and the monkey and compare the relative lengths of this posterior limb. (ab) An anterior limb. This limb is formed by the remaining bones of the tarsus and metatarsus. Examine a model of a foot in which the joint-cavities are represented, and note the amount of synovial membrane found in the joints of the anterior limb. These membranes produce an elastic resistance to any force applied to the anterior limb of the longitudinal arch. Shocks transmitted through it to the leg, pelvis, and trunk are much lessened by this arrangement. The anterior limb is subdivided into a medial pillar, formed by the talus, the navicular, the three cuneiform, and the three medial metatarsal DISSECTION OF THE LOWER KXTIiK.MITV bones, and a lateral pillar, formed by the calcam-mn, the cuboid, and the two lateral metatarsal bones. (b) Transverse arch. Where is this arch to be found and what function does it subserve? (c) Lateral arch. This arch is convex laterally and extends from the heel to the base of the little toe. Determine in what directions pressure exerted from above is radiated by this arrangement of the arches. What factors assist in the maintenance of the aivh of the foot? Study, in this connection, especially the tendon of the M. peronaeus. What is flat-foot? Where is the sprin.i: of the foot? In flat-foot the line of tenderness generally corre- sponds to the line of Chopart's joint. Examine the medial margin of the foot and determine the position of the following : (a) Sustentaculum tali. (b) Tuberositas ossis navicularis. (c) Line of calcaneo-astragaloid joint (articulatio talocalcanea) . (d) Line of tarsometatarsal joints (articulationes tarsometatarseae) . (e) Lines of metatarsophalangeal joints (articulationes metatarsopha- langeae). Examine upon the lateral margin of the foot— (a) Trochlear process (processus trochlearis) , not always present. (b) Line of calcaneocuboid joint (articulatio calcaneocuboidea) . In con- nection with Chopart's amputation it is important to know the structures which serve as guides in finding the mid-tarsal joint. (c) Tuberositas ossis metatarsalis. What is its relation to the articula- tiones tarsometatarseae? What is Lisfranc's ligament? (Vide Cunningham's Systematic Anatomy, p. 1218.) Examine now the skin covering the sole of the foot. Note its general characteristics and compare it with the skin of the palm of the hand. How does it compare with the skin over the dorsum of the foot ! Which is the more mobile, and which is the thinner ? Note the callosities that form about the heel and the ball of the toes. In standing which parts of the sole come in contact with the floor? The foot should be firmly fixed and the toes extended, thus rendering the plantar aponeurosis tense. Make the following incisions : (1) A perpendicular incision extending down the middle of the sole. (2) A transverse incision across the sole at the clefts of the toes. (3) A medial incision extending the length of each toe. Reflect the flaps of skin and study the fascia beneath. 176 LABORATORY MANUAL OF HUMAN ANATOMY Superficial Fascia of Sole. This fascia consists of but one layer, and resembles the fas- ciae of the palm of the hand and of the scalp. Note the peculiar character of the fat and its disposition. Thick fibrous processes will be found which connect this fascia to the skin. Dissect away this fascia carefully and study the following: Bursae. (a) Subcutaneous calcanean bursa (bursa subcutanea calcanea). (Vide Spalteholz, p. 348.) (b) Bursa in the ball of the great and of the little toe. Occasionally a small artery and nerve may be found passing into these bursae. When inflamed they are very painful. How may the formation of these subcutaneous bursae be accounted for? Veins. (a) Digital plantar veins (Vv. digitales plantar es}. (b) Plantar venous arch (arcus plantaris venosus). (ba) Intercapitular veins (Vv. inter capitular es} , single or dou- ble, passing between each pair of toes to join the Vv. digitales dorsales. (c) Plantar venous network (rete venosum plantare). Determine the exact course of the venous blood coming from the sole of the foot. Nerves. (a) Medial calcanean branches of the tibial nerve (rami calcanei N. tibialis). (b) Cutaneous branches of the plantar nerves. Lymphatics. Determine the exact course of the lymphatics of the sole of the foot. (Vide Toldt, Fig. 1090.) Plantar Aponeurosis (Aponeurosis plantaris.) Eemove now the superficial fascia and study the aponeurosis plantaris. (Vide Spalteholz, Fig. 397.) Note the density of this aponeurosis. It is attached poste- riorly to the os calcaneum and passes forward to cover the whole of the musculature of the foot. It is attached to the medial and lateral margins of the foot, and passes without interruption into the fascia of the dorsum of the foot. This aponeurosis, like the palmar aponeurosis, may be divided into a middle, a medial, and a lateral part. How does the strength of the middle part compare with that of the medial and lateral parts'? Trace this medial part forward, after having determined its posterior attachment; dissect out the five proc- esses into which it divides. Determine their relations to the Ligg. vaginalia and the phalanges. Dissect out carefully the transverse bundles (fasciculi transversi). DISSECTION OF THE LOWER EXTREMITY 177 The medial part is the weakest. It is continuous posteriorly with the ligamentum laciniatum, and is attached along the medial margin of the foot to the tarsal and first metatarsal bones. What muscles does this part cover! The lateral part is stronger than the medial. It is attached behind to the lateral tubercle of the os calcaneum and in front to the tuberosity and the lateral border of the fifth metatarsal. Posteriorly all three divisions give origin to muscles. From the deep surface of the plantar aponeurosis a medial and a lateral process are given off, which pass downward to fuse with the fascia interossea plantaris and to become attached to the tarsal bones. Three separate muscular compartments are thus formed. These septa may be seen if the plantar aponeurosis be incised in the median line from heel to toe and reflected each way. Contraction of the plantar fascia gives rise to the condition known as pes cavum. The division of the aponeurosis is most easily accomplished one inch in front of its attachments to the os calcaneum, where it is narrowest. Pus may collect beneath the fascia, and it is apt to burrow, because the aponeurosis is so dense that pus cannot perforate it. Occasionally pus may pass through one of the small foramina formed by the passage of small arteries and nerves through the aponeurosis. In this case two abscess-cavities will be formed. Such a condition is known as the abces en bissac. Eemove the aponeurosis plantaris and study the structures beneath. FIG. 72. J M. flexor dig. M. flexor hall, long Caput plantare • \\< / J 2 Relation of the tendons of the M. flexor digitoruin longus and of the M flexor halhieis longus x*n from the upper side. (From Gegenbaur, Lehrb. der Anat. des Mensch., Leipzig, 1H99, / Fig. 339.) Superficial Layer of Muscles of the Sole. (Vide Spalteholz, Fig. 398.) Note the form, position, origin, insertion, action, and inner- vation of each. 12 178 LABORATORY MANUAL OF HUMAN ANATOMY (a) Short flexor muscle of the toes (M. flexor digit orum brevis). Exam- ine its ligamentous sheath (ligamentum vaginale), annular ligament (ligamentum annular e), and the cruciate ligament (ligamentum cruciatum ) . After having made a careful study of this ligamentous sheath, incise it in the medial line and reflect each way, preserving care- fully the vessels and nerves. Note the synovial sheath (vaginae tendinum digitales pedis) surrounding the flexor tendons. (Vide Spalteholz, Fig. 407.) What relations exist between the tendons of the long and of the short flexors of the toes? Compare these relations with those found in the hand. (b) Abductor muscle of great toe (M. abductor hallucis}. (c) Abductor muscle of little toe (M. abductor minimi digiti). Divide these muscles at their origin and reflect them forward. Exercise great care and avoid injury to yessels and nerves immediately beneath. Plantar Arteries. (Vide Spalteholz, Fig. 481.) Determine the relations of these different arteries. What is the linear guide for each artery ? All the branches are mentioned here, although many will not be seen at this stage of the dis- section. (a) Medial plantar artery (A. plantaris medialis) (0. T. internal plan- tar). (aa) Superficial branch (ramus super ficialis) . (ab) Deep branch (ramus profundus). (b) Lateral plantar artery (A. plantaris lateralis) (0. T. external plan- tar). (ba) Plantar arch (arcus plantaris). (baa) Plantar metatarsal arteries (Aa. metatarseae plan- tares). (bab) Perforating branches (rami perforantes) . (bac) Digital plantar arteries (Aa. digitales plantar es). With what arteries do the above anastomose? Dissect out the veins accompanying the arteries and trace them into larger stems. Plantar Nerves. (Vide Spalteholz, Figs. 824 and 825.) Determine what muscle is supplied by each nerve, also the exact cutaneous supply. What is muscle sense! (a) Medial plantar nerve (N. plantaris medialis) (0. T. internal plantar). (aa) Common digital plantar nerves (Nn. digitales plantar es com- munes). (ab) Proper digital plantar nerves (Nn. digitales plantar es pro- prii). (b) Lateral plantar nerve (N. plantaris lateralis) (0. T. external plan- tar). (ba) Superficial branch (ramus superficialis) . Common digital plantar nerves (Nn. digitales plantar es communes). DISSECTION OF THE LOWER EXTREMITY 179 Proper digital plantar nerves (Nn. digitales plantar -es proprii). (bb) Deep branch (ramus profundus). Second Layer of Muscles and Tendons of the Sole. (a) Tendons of the M. flexor digitorum longus. (aa) Quadrate muscle of the sole (M. quadratics plantae) (0. T. accessorius muscle). (Fig. 72.) Two planes of fibres will be found in this muscle. Dis- sect both out carefully and determine their relations to the different tendons. (ab) Lumbrical muscles (Mm. lumbricales) . Determine the exact modes of origin from the tendons of the long flexor and trace them forward to the tendons of the long extensor. These little muscles act chiefly through the above tendons and produce, when active, a flexion of the first phalanx and extension of the second and third. Dissect out the bursae Mm. lumbricalium pedis. (b) Tendon of the long flexor of the great toe. Determine the relative position of this tendon and dissect out the tendinous process pass- ing over to the tendon of the long flexor of the digits. Divide the tendons of the M. flexor longus digitorum, M. flexor longus hallucis, M. quadratus plantae, and the plantar ves- sels and nerves near the os calcaneum and reflect them down- ward. Third Layer of Muscles of the Sole. (Vide Spalteholz, Fig. 400.) (a) Short flexor muscle of great toe (M. flexor hallucis brevis). (b) Adductor muscle of great toe (M. adductor hallucis). (ba) Oblique head (caput obliquum). (bb) Transverse head (caput transversum). (c) Short flexor muscle of fifth toe (M. flexor digiti quinti brevis). (d) Opposing muscle of little toe (M. opponens digiti quinti). Sever the M. flexor digitorum brevis and the caput obliquum of the M. adductor hallucis at their origins and reflect them downward. Complete now the study of the arcus plantaris. De- termine where the deep branch of the dorsal artery of the foot passes into the planta. Note the deep branch of the lateral plantar nerve close by the arch. Displace the digital vessels and nerves forward and sever t short flexor of the little toe and the transverse head of adductor hallucis at their origins and reflect. Note the strong bands of fibrous tissue (ligamentum capitulorum transversum) passing between the heads of the metacarpal bones. 180 LABOKATORY MANUAL OF HUMAN ANATOMY Fourth Layer of Muscles of the Sole. (a) Plantar interosseous muscles (Mm. inter ossei plantar es). (b) Dorsal interosseous muscles (Mm. inter ossei dor sales). Determine the form, position, origin, insertion, action, and innervation of each, and compare them with their homologues in the hand. Note that they are covered by a thin layer of inter- osseous fascia (fascia interossea). The points of insertion of the M. tibialis posterior will now be exposed. Dissect out the different reflections of its tendons and determine to what bones each is attached. Dissect out the tendon of the M. peronaeus longus. Note that it runs in a sulcus covered over by the ligamentum longum plantae. Dissect down to the tendon and trace it to its insertion, noting the plantar synovial sheath (vagina tendinis M. peronaei longi plant aris). (Vide Spalteholz, Fig. 407.) What role does it play in maintaining the arch of the foot 1 JOINTS OF THE LOWER EXTREMITY. The hip- joint has been studied already. The other joints should now be carefully dissected. Arterial Anastomosis about the Knee-joint. Before dissecting the knee-joint, review the various blood- vessels about the knee and study the most important anasto- moses. (Fig. 73.) Knee-joint (Articulatio genu). (Figs. 73-77.) Remove the popliteal vessels and nerves. The tendons of the muscles surrounding the joint should be left in place, so that their relations to the different ligaments may be studied. Divide the M. quadriceps extensor about eight centimetres above the patella and allow the lower part to remain in situ. Trace each of the articular arteries to its termination. Study the following : (a) Articular capsule (capsula articularis) . (b) Fibular collateral ligament (Lig. collaterale fibulare) (0. T. long external ligament). (c) Tibial collateral ligament (Lig. collaterale tibiale) (0. T. internal lateral ligament). (d) Oblique popliteal ligament (Lig. popliteum obliquum) (0. T. pos- terior ligament). (e) Arcuate popliteal ligament (Lig. popliteum arcuatum). Observe the retinaculum Lig. arcuati. DISSECTION OF THE LOWER EXTREMITY (/) Ligament of the patella (Lig. patellae}. (fa) Retinaculum patellae mediale. (fb) Retinaculum patellae laterale. 181 Fie. 73. A. genu sup. lat. A. genu inf. lat. .. A. rec. tib. post. V Ramus flb. A. tib. post. - —A. genu suprema ..A. genu sup. med. ....A. genu inf. med. -A. rec. tib. ant. A. tibialis anterior Arterial anastomosis about the knee. (After Poirier et Charpy, Traite d'Anat hum., Paris, 1901, 2 ed., t. ii. p. 831, Fig. 449.) Make a vertical incision into the joint on either side of the patella and ligamentum patellae. The common extensor ten- don and the patella should now be thrown downward and the following internal structures studied : (g) Lateral meniscus (meniscus lateralis) (0. T. external semilunar fibro- cartilage ) . (h) Medial meniscus (meniscus medialis) (0. T. internal semilunar fibro- cartilage). (i) Transverse ligament of the knee (Lig. transfer sum genu). (j) Crucial ligaments of the knee (Ligg. cruciata genu). (ja) Anterior crucial ligament (Lig. cruciatum anterius). (jb) Posterior crucial ligament (Lig. mirintinu postrriii*). (k) Patellar synovial fold (plica synovialis patellaris) (0. T. ligamentum mncosum ) . What is the significance of this fold? (0 Alar folds (plicae alares) (0. T. ligamenta alaria). 182 LABORATORY MANUAL OF HUMAN ANATOMY Study with care the reflections of the synovial membrane. It is the most extensive of any in the body, and is of great practical importance because of its frequent involvement in disease. Look for " loose bodies" in the cavity of the knee-joint; occasionally one is found. Eemember that in a Rontgen-ray Tend. M. quad, fern Lig. proprium pat. med. Meniscus medialis FIG. 74. Tend. M. adduct. mag. B. infrapat. prof. .- A. genu iuf. med. .. . M. semimemb. [• Lig. collat. tib. ..M. gastroc. (caput med.) Articulatio genu, medial view. The capsula articularis is removed to demonstrate its lines of attachment to the feimir and tibia. (From Poirier et Charpy, Traite d'Anat. hum., Paris, 1899, 2 ed., t. i. p. 737, Fig. 739.) picture the sesamoid bone in the origin of the M. gastrocnemius has before now been mistaken for such a i i loose body. ' ' Having charted the length and breadth of the muscular attachments on the tibia and fibula, remove the muscles and study the articulation between the bones. DISSECTION OF THE LOWER EXTREMITY 183 Lig. ant. men. med. ... Meniscus medialis_ Lig. post. men. med. . FIG. 75. Lig. transversum .. Lig. ant. men. lat. Lig. cruoiatum ant. .Lig. post. men. lat. . Meniscus lateralis Lig. cruciatum post. Condylus medialis et lateralis with menisci. (From Poirier et Charpy, Traits d'Anat. hum., Paris, 1899, 2 ed., t. i. p. 733, Fig. 737.) FlG. 76. Lateral intertrochleo-. condylar groove Lig. cruciatum. anterius Lig. collat. nbulare- Medial intertrochleo- condylar groove Lig. cruciatum post. Lig. transversum genu Lig. collat. tibiale Crucial ligaments of the knee (Ligg. cruciata genu) ; anterior view. The femur is flexed at right angles to the tibia. (From Poirier et Charpy, Traite d'Anat. hum., Paris, 185W, t. i. p. 74U, h i 184 LABORATORY MANUAL OF HUMAN ANATOMY Tibiofibular Articulation (Articulatio tibiofibularis) (O. T. Superior Tibiofibular Articulation). (Fig. 78.) (a) Articular capsule (capsula articularis) . (b) Ligaments of the head of the fibula (Ligg. capituli fibulae) (0. T. anterior and posterior superior tibiofibular ligaments). (c) Interosseous membrane of leg (membrana interossea cruris) (0. T. middle tibiofibular ligament). FIG. 77. Supracondylar process Tendon M. poplitei -.- BursaM. poplitei ... B. suprapatellaris - Cavum articulare ^.. Notch due to adipose mass Inferior compartment Synovial spaces of the articulatio genu, lateral view. (From Poirier et Charpy, Trait6 d'Anat. hum., Paris, 1899, 2 ed., t. i. p. 744, Fig. 745.) Tibiofibular Syndesmosis (Syndesmosis tibiofibularis) (O. T. Inferior Tibiofibular Articulation). Study- (a) Anterior ligament of lateral malleolus (Lig. malleoli lateralis ante- rius). (b) Posterior ligament of lateral malleolus (Lig. malleoli lateralis pos- terius ) . DISSECTION OF THE LOWER EXTREMITY L85 After the ankle-joint has been studied, the tibia and fibula should be sawn through about five centimetres above their lower articular surfaces. Make a coronal section of the bones and study the ligament passing between their lower extremities. Establish the continuity of the synovial membrane of this joint with that of the ankle. Remove the crucial ligament of the leg and the transverse ligament of the foot, also the tendons passing over the ankle, and dissect out the joints of the foot. FIG. 78. .A. rec. tib. ant. .A. tib. ant. .Memb. interos. .Ramus perf. A. peron. .A. tib. ant. Membrana interossea cruris. (After Poirier et Charpy, Tralt6 d'Anat. hum., Paris, 1899, 2 ed., t. i. p. 756, Fig. 755.) Articulations of the Foot (Articulationes Pedis). (Figs. 79-82.) Talocrural Articulation (Articulatio talocruralis) (Ankle-joint). In removing the soft parts in order to expose the joint, take great care not to injure the very delicate anterior part articular capsule. 186 LABORATORY MANUAL OF HUMAN ANATOMY (a) Articular capsule (capsula articular is ). (b) Deltoid ligament (Lig. deltoideum) (0. T. internal lateral ligament and anterior and posterior tibiotarsal ligaments). (ba) Tibionavicular ligament (Lig. tibionavi culare ) . (bb) Calcaneotibial ligament (Lig. calcaneotibiale). (be) Anterior talotibial ligament (Lig. talotibiale anterius). (bd) Posterior talotibial ligament (Lig. talotibiale posterius). (c) Anterior talofibular ligament (Lig. talofibulare anterius) (0. T. anterior fasciculus of external lateral ligament). (d) Posterior talofibular ligament (Lig. talofibulare posterius) (0. T. posterior fasciculus of external lateral ligament). (e) Calcaneofibular ligament (Lig. calcaneofibulare) (0. T. middle fasciculus of external lateral ligament). FIG. 79. Lig. talotibiale post. Lig. talocalc. post. j. naviculari- cuneiforme dorsale Lig. tibio- calcaneum Articulationes talocruralis et intertarseae. Medial view. (From Poirier et Charpy, Trait<§ d'Anat. hum., Paris, 1899, 2 ed., t. i. p. 761, Fig. 759.) The articular capsule should be opened anteriorly and poste- riorly after it has been cleaned. When opened, a good view of the interior of the joint may be had and the remaining ligaments more easily defined. Study sagittal and frontal sections through this joint on preparations in the anatomical museum; examine closely the relations of the ligaments and the folds of the capsule to the joint-cavity. Clean away all the muscles and tendons upon the foot, after DISSECTION OF THE LOWER EXTREMITY 187 the length and breadth of their attachments have been charted, and study the following joints. Intertarsal Articulations (Articulationes intertarseae). Taloealcaneonavicular Articulation (Articulatio talocalcaneonavicularis) . This is the more anterior of the two separate joint-cavities which exist between the talus on the one hand and the navicular bone and the calcaneus on the other. The posterior of the two joint-cavities is called the articulatio calcanea. (See Spalteholz, Fig. 271.) FIG. 80. Inferior tibiofibular interosseous ligament Lig. malleoli lateralis anterius Lig. talofibulare ant. Lig. talonaviculare [dorsale] Lig. calc. cuboi(f dorsale Lig. cuboideonavieulare dorsale Lig. naviculari- cuneifonn. dors. . !,„, ( Pars calcaneo- -Lig.bifur-l navi(.ularis rr,t:atn™. , 1 Pars mlouiro- cuboid. -a Lig. talocalc. Lig. calc.-flbulare lat" Articulationes talocruralis et intertarseae. Lateral view. (From Poirier etCharpy, Truite d'Anat. hum., Paris, 1899, 2 ed., t. i. p. 760, Fig. 758.) Study now : (a) Talocalcanean articulation (articulatio talocalcanea) . (aa) Articular capsule (capsula articularis) . (ab) Lateral talocalcanean ligament (Lig. talocalcaneum lat- erale) (0. T. external calcaneo-astragaloid ligament) (ac) Medial talocalcanean ligament (Lig. talocalcaneum medialc) (0. T. internal calcaneo-astragaloid ligament). (ad) Anterior talocalcanean ligament (Lig. talocalcaneum ante- rius). (ae) Posterior talocalcanean ligament (Lig. talocalc (b) Chopart's Inverse articulation of the tarsus (articulatio tarsi transversa [ Choparti] ) . 188 LABORATORY MANUAL OF HUMAN ANATOMY This demands particular attention because it is of great importance to the surgeon. Chopart's amputation of the foot is made through this joint. Besides, the pain of flat-foot is localized in this joint. (ba) Talonavicular articulation (articulatio talonavicularis) . Observe that this is really only a part of the articulatio talocalcaneonavicularis. (baa) Articular capsule (capsula articularis) . (bb) Calcaneocuboid articulation (articulatio calcaneocuboidea). (bba) Articular capsule (capsula articularis). (c) Cuneonavicular articulation (articulatio cuneonavicularis) . (d) Interosseous ligaments of tarsus (Ligg. tarsi interossea). (da) Interosseous talocalcanean ligament (Lig. talocalcaneum interosseum ) . (db) Interosseous cuneocuboid ligament (Lig. cuneocuboideum interosseum ) . (dc) Interosseous intercuneiform ligaments (Ligg. inter cunei- formia interossea). (e) Dorsal ligaments of tarsus (Ligg. tarsi dorsalia). (ea) [Dorsal] talonavicular ligament (Lig. talonaviculare [dor- sale]) (0. T. superior astragalonavicular ligament). (eb) Dorsal cuneocuboid ligament (Lig. cuneocuboideum dor- sale). (ec) Dorsal cuboideonavicular ligament (Lig. cuboideonavicu- lare dorsale). (ed) Bifurcate ligament (Lig. bifurcatum). (eda) Calcaneonavicular part (pars calcaneonavicularis) (0. T. superior or external calcaneonavicular ligament ) . (edb) Calcaneocuboidal part (pars calcaneocuboidea) (0. T. internal calcaneocuboid ligament). (ee) Dorsal calcaneonavicular ligament (Lig. calcaneonavicular e dorsale). (ef) Dorsal navicular cuneiform ligaments (Ligg. naviculari- cuneiformia dorsalia). (f) Plantar ligaments of tarsus (Ligg. tarsi plantaria). (fa) Long plantar ligament (Lig. plantare longum) (0. T. long calcaneocuboid ligament). (fb) Deep ligaments of tarsus (Ligg. tarsi profunda). (fba) Plantar calcaneocuboid ligament (Lig. calcaneo- cuboideum plantare). (fbb) Plantar calcaneonavicular ligament (Lig. calcaneo- naviculare plantare) (0. T. inferior calcaneo- navicular ligament). (fbc) Navicular fibrocartilage (fibrocartilago navicu- laris). (fbd) Plantar navicular cuneiform ligaments (Ligg. navicularicuneiformia plantaria) . (fbe) Plantar cuboideonavicular ligament (Lig. cuboid- eonaviculare plantare). DISSECTION OF THE LOWER EXTREMITY 189 (fc) Plantar intercuneiform ligaments (Ligg. intercuneiformia plantana). (fd) Plantar cuneocuboid ligament (Lig. cuneocuboideum plan- tare) . FIG. 81. Lig. calcaneo- naviculare plantare- Lig. nayiculari-. cuneiforme Lig. intercun. plantare Lig. tarsometatarseum... ..Lig. plantare longum ..Lig. cuboideonavic. plantare . Lig. plantare longum (superficial part) M. peronaeus long. Articulationes intertarseae and tarsometatarseae. Plantar view. (From Poirier et Charpy, Traite d'Anat. hum., Paris, 1899, 2 en,<-ic and shoulder regions. (After Toldt. Aunt. Atlas, Wirn, 1900, 2 Aufl., p. 702, Fig. 1 206 LABORATORY MANUAL OF HUMAN ANATOMY Vv. temporales superflcial V. temporalis media FIG. 87. Vv. palpebrales superiores Vv. palpebrales inferiores V. frontalis V. nasofrontalis J^k Vv. nasales extcrnae V. angularis V. transversa 1'aciei V. labialis superior Venous plexus about the ductus paroticleus V. anastomica faeialis '' V. labialis inferior ' Vv. parotideae anteriores V. faeialis anterior Vv. masseterk-au A. maxillaris externa . submentalis Glandula sv.bmasilht ris Vv. auriculares anteriores*'' V. occipitalis— ' V. auricularis posterior V. faeialis posterior •-' V. faeialis communis Fascia colli (lamina superficialis laid back) .Fascia praevertebralis V. cervicalis subcutanea V. cervicalis superficialis V. transversa scapulae. Lower belly of the M. omohyoideus "v ( enclosed in the deep layer of the- cervical fascia) Fascia coracodavicularis V. acromialis V. jugularis externa V. jugularis anterior Rete acromiale 'Fascia pectoralis (lamina profunda ) Kami pectorales of the A. and V. thoracoacromialis I 'Vv. deltoideae V. cephalica The superficial veins of the head and neck. ( After Toldt, Anat. Atlas, Wien, 1900, 2 Aufl., p. 664, Fig. 1046.) DISSECTION OF THE HEAD AND NECK 207 injury to the platysma, which lies in the superficial fascia. Observe the superior rami of the cutaneous nerve of the front of the neck (rami superiores N. cutanei colli), superficial to the platysma. The superficial lymphatic channels can be well seen only in especially injected specimens. (Vide Fig. 86.) Study the form, position, origin, insertion, innervation, and action of the platysma. Is the muscle in general placed super- ficial or deep as regards the panniculus adiposus ? Is the fat of double chin premuscular, retromuscular, or both ? Note that the platysma always moves with the skin of the neck. The loose areolar tissue between the platysma and the superficial layer of the fascia colli permits of free movement. What is the relation of the anterior jugular and of the external vein to the platysma? Why is the platysma called the muscle of fright? (Cf. Duchenne, Mecanisme de la physionomie humaine, Figs. 61, 62, and 63.) Why is it easier to pinch up a fold of skin vertically than trans- versely in the neck! What effect would the platysma have on the edges of a wound passing through the skin and muscles at right angles to the course of its fibres? Structures between the Platysma and the Surface of the Fascia Colli. Reflect the platysma from below upward, taking care not to injure the subjacent nerves and veins. Veins. External jugular (V. jugularis externa). (a) Posterior auricular (V. auricularis posterior). (b) Anterior jugular (V. jugularis anterior}. How would you draw a line on the surface of the neck correspond- ing to the position of the external jugular vein? Observe the super- ficial lymphatic glands (lympJioglandulae cervicales superficiales) along the external jugular vein. How many are there? Whence do they draw lymph? (Vide Figs. 86 and 93.) Nerves. Branches of the cervical plexus. (a) Lesser occipital nerve (N. occipitalis minor). (b) Great auricular nerve (N. auricularis magnus). (c) Cutaneous nerve of the front of the neck (N. cutaneus colli) (0. T. superficial cervical). (ca) Upper rami (rami superiores). (cb) Lower rami (rami inferiores). Is a cutaneous nerve of the back of the neck cutaneus cervicis) present? (d) Supraclavicular nerves (Nn. supraclaviculares) . (da) Anterior (Nn. supraclaviculares anteriores) (0. T. supn sternal). 208 LABORATORY MANUAL OF HUMAN ANATOMY FIG. 87a. N. auricu- laris Ramus anterior. Vena jugularis _ anterior Rami anastornotici •Ute' of the N. facialis magnus ( Ramus posterior.^ Ramus superior of the N. cutaneus colli Ramus colli of the N. facialis (for the "* platysma) Rami superiores of the N. cutaneus colli Connecting branch to the N. facialis -1 Ramus inferior of the N. cutaneus ~"~ colli --. Vena jugularis externa *> if. occipitalis minor N. cutaneus cervicis (Var.) Ramus externus of the N. accessorius Trunk of the Nn. ~- supraclaviculares Nll. supraclavicu- lares posteriores Nn. supraclaviculares /' ,* anteriores Platysma "/ f:S If Nn. supraclaviculares medii The cutaneous branches from the cervical plexus to the head and neck and their relation to the platysma. The bundles of the latter have been pulled apart in places to show partially the nerves under it. ( After Toldt, Anat. Atlas, \Vien, 1903, p. 819, Fig. 1251. ) DISSECTION OF THE HEAD AND NK< K 209 (db) Middle (Nn. supraclaviculares medii) (0. T. supra- clavicular). Note that the direction of the six principal branches corresponds to six lines radiating from a point at the middle of the posterior border of the M. sternocleidomastoideus. Branches of facial nerve to neck. (a) Branch to front of neck (ramus colli N. facialis). Note its anastomosis with a branch of the N. cutaneus colli. Deep Cervical Fascia and Aponeuroses. (Figs. 87, 88, and 89.) At this stage, before proceeding further with the dissection, the student will do well to read a good description of the deep cervical fascia. One of the best descriptions is that in Poirier et Charpy, t. ii. pp. 409-430. If the student does not read French easily, he will find a brief description in Cunningham's Text- Book of Anatomy, 1902, pp. 373, 374, 1178, 1179. In the descrip- tion, pay attention especially to the following points and verify each as the dissection goes on : General subdivision of the deep fascia and aponeuroses of the front of the neck into — (a) A superficial part (fascia colli, superficial layer), corresponding to the sternocleidomastoid muscles. (b) A middle part (fascia colli, deep layer) (0. T. pretracheal fascia), corresponding to the subhyoid muscles. (c) A deep part (fascia praevertebralis) , corresponding to the prever- tebral muscles. Between (b) and (c) are a large central compartment containing viscera and a small lateral compartment on each side containing the great vessels, each compartment having a sheath. The Superficial Part (Fascia colli, superficial layer). Attachments. Above, to prominentia occipitalis externa, linea nuchae superior, processus mastoideus, and to the fascia parotideomasseterica and the inferior border of the mandibula. Below, to the spina scapulae, anterior border of clavicle, upper border of sternum. Behind, to the ligamentum nuchae. In front, to same layer of opposite side. Note splitting of layer to enclose sternocleidomastoid muscle (M. sternocleidomastoideus) and again to enclose the trapezius muscle (M. trapezius) ; it does not split above the sternum to make suprasternal compartments, as ordinarily described. Observe firm transverse fixation of superficial layer of fascia colli to anterior surface of hyoid bone. This is the true line of demarcation between the head and the neck; the suprahyoid muscles are all innervated by cerebral nerves. The mtermuscu- 14 210 LABORATORY MANUAL OF HUMAN ANATOMY lar septa separating the muscles of the front of the neck (collum) from those of the back of the neck (cervix) are attached to the deep surface of the layer under description; they pass medial- ward and a little forward, and become attached to the lateral portion of the fascia praevertebralis which encloses the scalene FIG. 88. K Fascia parotideomasseterica' — Platysma M. sternocleidomastoideus — ^j Lamina profunda fasciae colli— Regio colli anterior M. sterno- cleidomastoideus — ^8P Lamina profunda — ~^H ll ^jffl. ,JJH Lamina profunda fasciae colli Platysma - The fascia colli on the right side after the removal of the platysma. The superficial lamina is partly taken away in places where it is sharply separated from the deep lamina. The middle portion of the sternocleidomastoid muscle has been removed to show the deep layer of the fascia colli, under which is seen the upper belly of the omohyoid muscle shining through. (After Toldt, Anat. Atlas, Wien, 1900, 2 Aufl., p. 287, Fig. 525.) muscles (Mm. scaleni) and extends between the anterior and posterior tubercles of the transverse processes of the cervical vertebrae. Note that where the superficial layer of the fascia colli is covered by the platysma it is thinner than elsewhere. Examine closely various parts of the fascia under description : DISSECTION OF THE HEAD AND NK< K I'll 1. Sternomastoid portion. 2. Parotid portion. 3. Submaxillary portion. 4. Median suprahyoid portion. 5. Median infrahyoid portion. 6. Supraclavicular portion. The Middle Part (Fascia colli, deep layer] ("omoclavicular aponeurosis" of Richet). Extent. Vertically, from os hyoideum to thorax. Laterally, from one M. omohyoideus to the other. FIG. 89. Sheath of the. scalene muscles Adipose mass Space behind the fascia praeverte- bralis I'rrviseeral --' space Superficial sub- aponeurotic space ...Visceral sheath The interaponeurotic spaces, seen in section and supposed to be injected. The visceral and vascular sheaths, the sagittal septa, and the fascia praevertebralis are represented by dotted lines, the middle aponeurosis by a heavy black line. The section passes immediately below the larynx. (From Poirier ct Charpy, Traits d'Anat. hum., Paris, 1901, 2 ed., t. ii. p. 426, Fig. 269.) Embedded in it are the omohyoid, sternohyoid, cleidohyoid, and thyreohyoid muscles. In lower forms this fascia is repre- sented by a single broad cleidohyoid muscle; in man it has become differentiated into several muscles with connective tissue between. (Gegenbaur.) 212 LABORATORY MANUAL OF HUMAN ANATOMY Distinguish in it— (1) A deep or intermuscular layer. (2) A superficial or premuscular layer. The suprasternal space (sometimes called Burns' space) is situated between the superficial layer of the fascia colli and the premuscular layer of the middle layer of the fascia colli. (Charpy.) Examine its contents. The interaponeurotic veins near the base of the neck are aspirated during inspiration. Hence this is the most dangerous area for the entrance of air into the veins during surgical operations. The Deep Part (Fascia praevertebralis). Note its two parts : (1) That extending from the anterior longitudinal ligament of the spine to the anterior tubercles of the transverse processes; it covers the pre vertebral muscles proper (Mm. longi colli et capitis). Observe the relation of the N. sympathicus to this part. (2) That extending from the anterior to the posterior tubercles around the Mm. scaleni. Observe the relation of the N. phrenicus and of the Nn. cervicales to this part. The fascia praevertebralis is part of the great common sheath of the body-cavity, being for the neck what the endothoracic fascia, the transversalis fascia, and the pelvic fascia are for the other visceral cavities. (Fawcett.) The Visceral Sheath. Contents. — Thyreoid gland, trachea, oesophagus, and pharynx. Shape. — In cross-section, semicylindrical. Attachments. Behind, by lateral angles to the vertebral column; between these two attachments is left a retrovisceral or prevertebral space. This is of especial interest in the retropharyngeal region (postpharyngeal abscess, etc.). Above, to base of skull. Below, extends into mediastinum. The Vascular Sheath. (a) Common sheath. (Note relation of ramus descendens N. hypo- glossi.) Observe attachment lateralward to deep layer of fascia colli and medialward to visceral sheath. The common sheath encloses b, c} and d. (b) Sheath for A. carotis (loose, to permit of pulsation). (c) Sheath for V. jugularis interna (dense, especially between artery and vein, septum vasorum). (d) Sheath for N. vagus (always satellite of artery, even in embryonic life, when vein is distant). DISSECTION OF THE 11KAI) AND NK( K 213 Some Enclosed Spaces of the Neck. (a) Subcutaneous space — between fascia superliruilis ;mphnriiliin>nalc$ dejctrae A. carotin iiitrriia Foramen jugulare - N. accessorius (ramus extern us) Rami pharyngei '-— Ramus thyreohyoideus _ N. laryngeus superior __ N. vagus (cervical part) M. aternocleidomastoideug (laid back) Plexus cervicalis N. phrenicus A. carotis communis _ _. Ramus cardiacus superior of the N. vagus ~ Plexus brachialis - A Bmnc-hing off of tin- N. recurrens A. pulmonalis Plexus canliacus NX- V. cava superior The anterior region of the neck. The head is strongly pull«'«l back. (After Toldt, Anat. Atlas, Wien, 1903, 3 Aufl., p. 878, Fig. 1321.) 222 LABORATORY MANUAL OF HUMAN ANATOMY Lymph-glands. (Vide Fig. 93.) (a) Superior deep cervical lymph-glands (lymphoglandulae cervicales profundae superiores). Viscera. (a) Larynx. (b) Pharynx. (c) Carotid skein (glomus caroticum) (0. T. intercarotid gland). Observe that some of the structures above enumerated become visible only after the parts have been loosened by dissection, that the greater cornu of the os hyoideum is in this space, and that, while the N. hypoglossus runs transversely in the spaces, the N. vagus and truncus sympathicus run vertically and the other large nerves obliquely. Muscular Triangle. Why is it so called ? Find and study the following structures : Muscles. (a) Sternohyoid (M. sternohyoideus). (b) Sternothyreoid (M. sternothyreoideus) . Arteries. (a) Superior thyreoid artery (A. thyreoidea superior). Nerves. (a) Muscular rami to M. sternohyoideus and M. sternothyreoideus (from the ramus descendens N. hypoglossi). (b) External ramus of superior laryngeal nerve (ramus externus N. laryng. sup.). (c) Recurrent laryngeal nerve (N. recurrens N. vagi). Viscera. (a) Larynx. (b) Trachea. (c) Thyreoid gland (glandula thyreoidea). (d) Oesophagus (on left side). Structures in the Anterior Median Line of the Neck and near it. (See Fig. 92, p. 221.) These should now be successively examined and studied. Suprahyoid Region. (a) Platysma. (b) Fascia superficial. (Note double chin.) (c) Space between anterior bellies of Mm. digastrici of two sides. (d) Mylohyoid muscles (Mm. mylohyoidei) and raphe between them. Infrahyoid Region. (a) Hyothyreoid membrane (membrana hyothyreoidea) (0. T. thyro- hyoid membrane). (b) Thyreoid cartilage (cartilago thyreoidea}. DISSECTION OF THE HEAD AND NECK 223 FIG. 93. Lympho- glandulae auriculares anteriores Lympho- glandulae ~ auricu- lares poste- riores Lympho- glandulae occipitales M. sternodcido mastoidcus (cut off] Lymphoglandulae eervi- *£-— cales profundae snperiores Lymphoglandulae eervicales profundae inferiores Ductus f Truncusjugularis lymphaticusj dexter Truncus subclavius Lymphoglandulae parotideae V. facialis anterior Mucous membrane of the lip , Lymphoglandulae submaxillares Union with the lymphoglandulae mediastinales antenores Lymphoglandulae Lymphoglandulae peetoralcs ih-ducts of tin- breast glands The lymphatic vessels of the head, the deep lymphatic vessels and lymph-glands of the neck and axillary space, and the lymphatic vessels of the female breast. ( After Toldt, Anat. Atlas, Wien, 1900, 2 Aufl., p. 703, Fig. 1085. ) 224 LABORATORY MANUAL OF HUMAN ANATOMY (c) Elastic cone and middle cricothyreoid ligament (conus elasticus, ligamentum cricothyreoideum [medium}} (0. T. cricothyroid membrane). Upon it lies the ramus cricothyreoideus of the A. thyreoidea superior. (d) Cricoid cartilage (cartilago cricoidea). (e) Cricothyreoid muscles (Mm. cricothyreoideae) . (/) Trachea. FIG. 94. M. sternocleidomastoideus. M. omohyoidcus M. scalenus medius ...M. thyreohyoideus M. trapezoideus M. scalenus posterior M. omchyoideus M. scalenus medius ...M. sternothy- reoideus - -M. scalenus posterior •C Muscles of the neck. (From Poirier et Charpy, Traite" d'Anat. hum., Paris, 1901, 2 ed., t. ii. p. 395, Fig. 249. ) (g) Isthmus of thyreoid gland (isthmus glandulae thyreoideae] . (h) Pyramidal lobe of thyreoid gland (lobus pyramidalis [Gl. thy- reoideae]). (i) Inferior thyreoid veins (Vv. thyreoideae inferiores). (j) Innominate artery (A. anonyma). (ja) Lowest thyreoid artery (A. thyreoidea ima). (k) Left innominate vein (V. anonyma sinistra). (I) Thymus. Surgical Anatomical Points. In the operation of laryngotomy the ligamentum cricothyreoideum is cut through transversely in its lower part, inferior to the ramus crico- thyreoideus of the A. thyreoideus superior. DISSECTION OF THE HEAD AND NECK 225 In the operation of tracheotomy the incision into the trachea is prefer- ably made between the cricoid cartilage and the isthmus of the thyreoid gland (so-called high operation). Muscles of the Neck. Study the form, position, insertion, and innervation of the following muscles : Those of the Second Layer. (a) Digastric muscle (M. digastricus) . (b) Stylohyoid muscle (M. stylohyoideus) . These are supplied by Nn. cerebrales. Those of the Third Layer. (a) Omohyoid muscle (M. omohyoideus) . (b) Sternohyoid muscle (M. sternohyoideus) . (c) Sternothyreoid muscle (M. sternothyreoideus) . (d) Thyreohyoid muscle (M. thyreohyoideus) . These are supplied by branches of the Nn. cervicales running in the descending ramus of the N. hypoglossus. The Sternoclavicular Joint and the Ligaments about the Clavicle, Sternum, and First Rib. The dissector of the upper extremity has removed the M. pectoralis major from the clavicle and sternum, and the sterno- clavicular joint (articulatio sternoclavicularis) may now be studied. (Cf. Spalteholz, Fig. 227.) What bony surfaces are here concerned ? Note the following : (a) Sternoclavicular ligament (Lig. sternoclaviculare) . (b) Interclavicular ligament (Lig. interclaviculare) . (c) Costoclavicular ligament (Lig. costoclaviculare) (0. T. rhomboid liga- ment). Cut through these ligaments and pull the clavicle lateralward so as forcibly to open the Sternoclavicular joint. Observe that the articular disk of fibrocartilage (discus articularis) separates two joint-cavities, each with a special capsule (capsula articu- laris} . The Root of the Neck. Remove with great care the areolar tissue at the root of the neck, avoiding injury to the finer rami of the sympathetic system. Study the structures on both sides of the body. Muscles. (a) Anterior , scalene (M. scalenus anterior). (b) Middle scalene (M. scalenus medius). (c) Posterior scalene (M. scalenus posterior). 15 226 LABORATORY MANUAL OF HUMAN ANATOMY (d) Smallest scalene (M. scalenus minimus] (inconstant). Study the relation of these to surrounding structures and note espe- cially the very important structures related to the most anterior of the three muscles. Arteries. (a) Subclavian artery (A. subclavia). (Vide Fig. 16.) Branches : Medialward from the M. scalenus anterior. (aa) Vertebral (A. vertebralis) . (ab) Internal mammary (A. mammaria internet). (ac) Thyreocervical trunk (truncus thyreocervicalis) . (aca) Inferior thyreoid (A. thyreoidea inferior}. (acb) Ascending cervical (A. cervicalis ascendens). (ace) Superficial cervical (A. cervicalis superficialis) . (acd) Transverse scapular (A. transversa scapulae). Behind the M. scalenus anterior. (ad) Costocervical trunk (truncus costocervicalis) (0. T. supe- rior intercostal). (ada) Highest intercostal artery (A. intercostalis su- prema) (0. T. superior intercostal proper). (adb) Deep cervical artery (A. cervicalis profunda). Between the Mm. scaleni. (ae) Transverse artery of neck (A. transversa colli). Veins. (a) Right and left innominate veins (Vv. anonymae dextra et sinistra). (aa) Inferior thyreoid veins (Vv. thyreoideae inferiores). (ab) Inferior laryngeal vein (V. laryngea inferior}. (ac) Lowest thyreoid vein (V. thyreoidea ima). (ad) Unpaired thyreoid plexus (plexus thyreoideus impar). (ae) Vertebral vein (V. vertebralis) . (aea) Deep cervical vein (V. cervicalis profunda). (b) Lower part of internal jugular vein (V. jugularis interna). (ba) An inferior thyreoid vein (V. thyreoidea inferior). Note the bulbus venae jugularis inferior. (c) Subclavian vein (V. subclavia). (ca) Thoraco-acromial vein (V. thoraco-acromialis) . (cb) Transverse vein of neck (V. transversa colli). Lymphatics. (a) Thoracic duct (ductus thoracicus). (Vide Fig. 93.) (b) Right lymphatic duct (ductus lymphaticus dexter). These may easily be mistaken for veins when first met with by the student. Nerves. (Vide Fig. 92.) (a) Phrenic nerve (N. phrenicus). Why should this nerve, arising in the neck, supply a muscle situated at the lower opening of the thorax? (b) Vagus nerve (N. vagus). Note its relation to the M. scalenus ante- rior, the trachea, and the A. carotis communis. (c) Lower part of cervical part of sympathetic trunk (truncus sym- pathicus). DISSECTION OF THE HEAD AND NECK 227 (ca) Middle cervical ganglion (ganglion cervicale medium). Does it rest on the A. thyreoidea inferior? (cb) Inferior cervical ganglion (ganglion cervicale inferius). Look for it in the depression between the transverse process of the seventh cervical vertebra and the neck of the first rib. (cc) Superior cardiac nerve (N. cardiacus superior). (cd) Middle cardiac nerve (N. cardiacus medius). (ce) Inferior cardiac nerve (N. cardiacus inferior). (cf) Subclavian loop (ansa subclavia [ Vieussenii] ) . (eg) Subclavian plexus (plexus subclavius). FIG. 95. M. trapeziu M. splenius M. spinalis cervicis^ M. inter spinali M. semispinalis cervic M. semispinalis capitis M. Lig. nuchae Lamina prof unda} -r^ - Lamina super-\-Fa*a ' ficwlu? \ M. levator scapulae ____ M. longissimus capitis ___ M. longissimus cervicis..,- M. iliocostalis cervicis^- M. scalenus medius.* Lymphoglandulae cervical es profundae"' infenores M, sternocleidomastoideus Vagina vasorum Platysma / , M. scalenus anterior / / M. longus capitis / f M. longus cotti / M. omohyoideus / M. sternothyreoideus / M. sternohyoideus / V. mediana colli of the IV. cervical vertebra V. cervicalis profunda Sinus vertebralis longi- tudinalis . vertebralis ^.Fascia praevertebralis —Lam. superflc. \ Fascia -.Lam. profunda) cotti -.interna ) -. . . , [ V. jugulans -externaJ — N. cervicalis descendens —N. vagus Truncus sympathicus A. carotis communis Ramus descendens N. h , A. and V. thyreoidea su \ \ V. jugularis anterior Jfascia praevertebralis -, Cavum pharyngis (pars laryngea) kima glottidis Cross-section through the neck at the level of the rima glottidis and through the body of the fifth cervical vertebra. Cut surface below the plane of section. (After Toldt, Anat. Atlas, Wien, 1900, 2Aufl.,p. 608, Fig. 984.) Viscera. (a) Summit of pleura (cupula pleurae). How far above the level of the sternal extremity of the clavicle does it extend into the neck? Which is higher, the left or the right? Is there a M. scalenus minimus or tensor of the cupula pleurae present? What is Sibson's fascia? What structures come into contact with the cervical pleura on the right side? What on the left? Note the fibrous expansions helping to support and fix the cupula (cf. Poirier et Charpy, t. iv., Figs. 250-252) : (1) From the apex of the dome to the fourth to seventh cer- vical vertebrae. 228 LABORATORY MANUAL OF HUMAN ANATOMY (2) From the lower half of the dome to the visceral sheath of the deep cervical fascia (pretracheal aponeurosis). (3) From the sixth and seventh cervical vertebrae to the first rib, often replacing the M. scalenus minimus. This is the ligamentum costopleurovertebrale. (4) From the anterior surface of neck of first rib to anterior surface of cupula. This is the ligamentum costopleu- rale. The two latter ligaments may be absent altogether. (b) Apex of lung (apex pulmonis). (c) Trachea, (d) Oesophagus. Cervical Plexus. (Vide Figs. 90 and 122.) The cervical plexus (plexus cervicalis) should now be studied. How is it formed ? What is its relation to the brachial plexus ? What are its exact situation and relation to surrounding parts? What muscles re- ceive their innervation from it? Review the communications formed by the cervical plexus with the cerebral nerves (N. hypoglossus, N. vagus, N. accessorius) . How is the sympathetic nervous system related to the cervical plexus ? Make drawings or diagrams to show the cervical plexus and its relations as they exist in your cadaver. General Review of Blood-vessels of Side of Neck. The dissector should now make a systematic review of all the blood- vessels of the side of the neck, reading on the structures from his text- book and making a sketch of the large arteries and their branches and the large veins and their tributaries. Further Study of Viscera of Neck. (a) Thyreoid gland (glandula thyreoidea). (aa) Isthmus of thyreoid (isthmus Gl. thyreoideae) . (ab) Pyramidal lobe (lobus pyramidalis) (inconstant). (oc) Right and left lobes (lobi dexter et sinister). (ad) Lobules of gland (lobuli Gl. thyreoideae) . (ae) Stroma of gland (stroma Gl. thyreoideae}. Are any accessory thyreoid glands present? (b) Trachea. (ba) Tracheal cartilages (cartilagines tracheales). (bb) Annular ligaments (Ligg. annulares trachealia). (be) Membranous wall (paries membranacea) . (c) Cervical part of gullet (oesophagus, pars cervicalis). BACK OF HEAD, NECK, AND TRUNK. The dissectors of the head and neck work in conjunction with those of the upper extremity. Make an incision in the middle line from the inion to the spine of the vertebra prominens, a second from the spine lateral- ward to the medial border of the acromion, and a third from the inion transversely lateralward (vide Fig. 3). Reflect the skin, DISSECTION OF THE HEAD AND NECK 229 taking no fat with it; the superficial fascia (fascia superficialis) is thus exposed. Why should the pain accompanying inflamma- tion at the nape of the neck — as, for example, in carbuncle be particularly severe I Superficial Vessels and Nerves. (Vide Fig. 4, p. 47.) Remove the superficial fascia piecemeal. The A. and V. occipitalis have already been met with in the dissection of the scalp, as have the terminals of the N. occipitalis major and M. occipitalis minor. The trunk of the N. occipitalis major pierces the M. trapezius; note exact spot, usually about two and one- half centimetres below the inion and one centimetre from the middle line. Is a N. occipitalis tertius present! If so, where does it pierce the M. trapezius and how is it related in distribu- tion to the N. occipitalis major? Find the dorsal cutaneous branches of the fourth, fifth, sixth, seventh, and eighth cervical nerves (rami cutanei dor sales Nn. cervicalium IV., V., VI., VII., VIII.}. Ascertain as closely as possible the area of skin inner- vated by each. Isolate the great auricular nerve (N. auricularis magnus) and follow its posterior branch (ramus posterior] ; its anterior branch (ramus anterior] will be studied later. Dissect out the cutaneous branches of the superficial cervical artery (A. cervicalis superficialis} and of the transverse artery of the scapula (A. transversa scapulae}. Note the correspond- ing veins. Into what lymph-glands do the lymphatics from this region empty? Make a drawing of the dissection at this stage. Upper Part of the Posterior Triangle of the Neck. Clean the surface of the trapezius muscle (M. trapezius} and the posterior border of the sternocleidomastoid muscle (M. sternocleidomastoideus} , which form the posterior and anterior boundaries of the triangle. Do not raise the M. sternocleidomast- oideus and take care not to disturb the nerves which lie beneath it at this stage of the dissection. Clean the floor of the triangle. Note the direction of the fibres of the splenius muscle of the head (M. splenius capitis} and of the elevator muscle of the scapula (M. levator scapulae} (0. T. levator anguli scapulae). Avoid injury to the rami musculares of the plexus cervicalis supplying the latter muscle; they lie usually upon its surface in close apposition with it. How is the apex of the triangle formed? Is the semispinalis muscle (M. semispinalis capitis} (0. T. corn- plexus) visible? If so, in what direction do its fibres run? Is 230 LABORATORY MANUAL OF HUMAN ANATOMY the occipital artery (A. occipitalis) to be seen in the triangle? Dissect out the portion of the accessory nerve (N. accessorius) belonging to the triangle. Note its exact point of emergence from the substance of the M. sternocleidomastoideus. Find the rami nmsculares of the plexus cervicalis which run across the triangle to disappear beneath the anterior margin of the M. trapezius. How are they related in position to the N. accesso- rius? Do you find any large cutaneous nerve of the cervix (N. cutaneus cervicis) I Broad Muscles of the Back (First Layer). (Vide Fig. 5, p. 49.) (a) Trapezius muscle (M. trapezius). After its surface has been thor- oughly cleaned, in conjunction with the dissector of the upper ex- tremity, the exact origin and insertion of the M. trapezius are to be established. Test the effect of contraction of its various por- tions, fixing alternately the head and the shoulder girdle. With the dissector of the upper limb, reflect the muscle and dissect the structures on its deep surface. Divide the attachment to the linea nuchae superior and protuberantia oecipitalis externa and cut through it about one centimetre from the cervical vertebral spines and five centimetres from the thoracic spines, taking care that the knife does not injure the underlying structures. Turn the muscle lateralward and allow the dissector of the upper limb to work out the distribution of the N. accessorius and the nerves from the cervical plexus going to the M. trapezius. Determine the origin and distribution of the A. cervicalis superficialis. In your cadaver does it come from the truncus thyreocervicalis or from the A. trans- versa colli? (ft) Broadest muscle of back (M. latissimus dor si}. The dissector of the arm has worked this muscle out and the dissector of the head should review his knowledge of it. (c) Elevator muscle of scapula (M. levator scapulae] (0. T. levator anguli scapulae) and neighboring vessels and nerves. Ex- amine the M. levator scapulae and the nerves on its surface (from the plexus cervicalis). Lift the muscle carefully and find beneath it — (ca) Descending branch (ramus descendens] of the A. transversa colli, often called the " posterior scapular artery." (cb) Dorsal nerve of scapula (N. dorsalis scapulae] (0. T. nerve to the rhomboids). Note the twigs from this nerve to the M. levator scapulae. Establish the exact origin and insertion of the muscle and test its action. Expose the scapular portion of the inferior belly (venter inferior] of the M. omohyoideus, and note the position of the A. transversa scapulae (0. T. suprascapular, or transversalis humeri) and the suprascapular nerve (N. suprascapularis) and DISSECTION OF THE HEAD AND NECK 231 the relation of each to the ligamentum transversum scapulae superius. Make a drawing of the part of the posterior triangle dissected and read in your systematic text-book descriptions of the various structures. Broad Muscles of the Back (Second Layer). (Fig. 96.) The larger and smaller rhomboid muscles (M. rhomboideus major, M. rhomboideus minor) have been worked out by the dis- sector of the arm. and may be conveniently reviewed. Broad Muscles of the Back (Third Layer). (Fig. 96.) The dissector of the head and neck now proceeds with the dissection of the muscles of the back, and permits the dissector of the upper extremity to study the parts. Observe the fascia nuchae. (a) Superior posterior serratus muscle (M. serratus posterior superior). Note its form and position. Establish its exact origin and inser- tion. Test its action. Is it concerned in inspiration or expiration? Find the nerves supplying it. What are they called? Is it a monomeric or a polymeric muscle ? Divide it close to its attachment to the vertebral spines and reflect it lateralward. (b) Inferior posterior serratus muscle (M. serratus posterior inferior). (c) Splenius ("bandage") muscle of head (M. splenius capitis). (d) Splenius muscle of neck (M. splenius cervicis) (0. T. splenius colli). Lumbodorsal Fascia (Fascia lumbodorsalis). (Vide Figs. 5 and 6.) The posterior layer of this fascia is now visible. That por- tion which corresponds to the thoracic spine is often spoken of as the " vertebral aponeurosis"; that portion corresponding to the small of the back is often called the ' ' lumbar fascia. ' ' Examine the posterior layer of the fascia lumbodorsalis. What are its medial and inferior attachments? How is it at- tached lateralward? What becomes of it above? These ques- tions may be answered (1) by making an incision through it in the middle of the thoracic region and passing the handle of the scalpel medialward and lateralward, and (2) by dividing the lumbar portion by a vertical cut made two or three centimetres from the median line and raising it from the subjacent M. sacro- spinalis. Then displace the M. sacrospinalis medialward and expose the anterior layer of the fascia lumbodorsalis. How is the anterior layer attached medialward? Note the fusion of the anterior and posterior layers lateralward. Cut through the anterior layer close to its medial attachment and lift it from the 232 LABORATORY MANUAL OF HUMAN ANATOMY FIG. 96. suprema Lin£anuchaeisuperior. M. semispinalis capitis M. sternocleidomastoideus (cut off and turned back) f capitis M. splenius< I cervicis M. levator scapulae M. serratus posterior superior Fascia lumbodorsalis Mm. intercostales externi M. serratus posterior inferior M. latissimus dorsi M. obliquus internus abdominis M. obliquus externus. abdominis Fascia lumbodorsal M. glutaeus medi M. glutaeus maximus Sutura lambdoidea Lig. nuchae Fascia nuchae (lamina profunda) Processus spinosus vertebrae cervicalis VII. M. serratus posterior superior M. rhomboideus minor M. rhomboideus major Processus spinosus vertebrae thoracalis XII. M. latissimus dorsi . obliquus externus abdominis Trigonum lumbale (Petiti) Cristailiaca Fascia glutaea The second layer of the broad muscles of the back, shown after removal of the latissimus dorsi and trapezms muscles; on the left side the rhomboid muscles also have been taken away. (AfterToldt, Anat. Atlas, Wien, 1900, 2 Aufl., p. 267, Fig. 505.) DISSECTION OF THE HEAD AND NECK 233 surface of the M. quadratus lumborum. Displace the latter medialward and the fascia covering the anterior surface of the latter will be brought into view. (This fascia was formerly called the anterior layer of the lumbar fascia.) Make a drawing of the structures in your cadaver corresponding to Spalteholz, Fig. 334. Long Muscles of the Back (First and Second Layers) (O. T. Third Layer of the Back). (Vide Fig. 4, p. 47.) Cut through the attachments of the M. splenius capitis and M. splenius cervicis, close to the spines of the vertebrae, and reflect the muscles upward and lateralward. Turn the whole of the posterior layer of the fascia lumbodorsalis with the M. ser- ratus posterior inferior lateralward. (a) Sacrospinal muscle (M. sacrospinalis) (0. T. erector spinae). What are the names given to the three main divisions of this muscle? Which is the largest of the three, and which the smallest? Pull the M. iliocostalis lateralward on the right side; reflect it on the left. Blood-vessels and nerves emerge between the M. iliocostalis and the M. longissimus dorsi and are the guide in dissection. (Vide Spalteholz, Fig. 336.) (aa) Lateral subdivision: iliocostal muscle (M. iliocostalis). (aaa) Iliocostal muscle of loins (M. iliocostalis lumborum) (0. T. sacrolumbalis). (aab) Iliocostal muscle of back (M. iliocostalis dorsi) (0. T. musculus accessorius). (aac) Iliocostal muscle of neck (M. iliocostalis cervicis) (0. T. cervicalis ascendens). Establish the exact origin and insertion of each. Test action. Find innervation. (ab) Middle subdivision: longest muscle (M. longissimus). (aba) Longest muscle of back (M. longissimus dorsi). (abb) Longest muscle of neck (M. longissimus cervicis) (0. T. transversalis cervicis). (abc) Longest muscle of head (M. longissimus capitis) (0. T. trachelomastoid). Establish exact origin and insertion of each. Test action. Find innervation. (ac) Medial subdivision: spinal muscle (M. spinalis). (aca) Spinal muscle of back (M. spinalis dorsi). (acb) Spinal muscle of neck (M. spinalis cervicis) (0. T. spinalis colli). (ace) Spinal muscle of head (M. spinalis capiti*). Establish exact origin and insertion of each. Test action. Find innervation. 234 LABORATORY MANUAL OF HUMAN ANATOMY Short Muscles of the Back (First, Second, and Third Layers). (Vide Spalteholz, Figs. 338, 339, and 340.) Cut away the attachments of the M. spinalis dorsi and reflect the M. longissimus dorsi lateralward. Reflect the M. longissimus capitis lateralward and upward. The M. semispinalis is now exposed. Clean it thoroughly. While cleaning the M. semi- spinalis capitis avoid injuring the posterior cutaneous rami of the cervical nerves (rami cutanei posteriores Nn. cervicalium) emerging from the substance of the muscle near the middle line. (a) Semispinal muscle (M. semispinalis). (Cf. Spalteholz, Fig. 338.) (aa) Semispinal muscle of back (M. semispinalis dorsi). (ab) Semispinal muscle of neck (M. semispinalis cervicis) (O. T. semispinalis colli). (ac) Semispinal muscle of head (M. semispinalis capitis) (0. T. complexus). Establish exact form, position, origin, insertion, action, and in- nervation of each. Cut away the attachments of the M. semispinalis from the ver- tebral spines and from the transverse processes, and study — (b) Multifidus ("much-divided") muscle (M. multifidus). What is its origin? Establish insertion, action, and innervation. Cut away the M. multifidus and expose the third layer of short muscles. Observe in the sacral region the posterior rami of the sacral and coccygeal nerves (rami posteriores Nn. sacralium et N. coccygei). (c) Rotator muscles (Mm. rotatores). (ca) Long rotator muscles (Mm. rotatores longi). (cb) Short rotator muscles (Mm. rotatores breves). (d) Elevators of the ribs (Mm. levatores costarum). (da) Short elevators of the ribs (Mm. levatores costarum breves). (db) Long elevators of the ribs (Mm. levatores costarum longi). (e) Interspinal muscles (Mm. interspinales) . (f) Intertransverse muscles (Mm. intertransversarii) . (fa) Cervical. (faa) Anterior (Mm. intertransversarii anteriores). (fab) Posterior (Mm. intertransversarii posteriores) . (fb) Lumbar. (fba) Medial (Mm. intertransversarii mediales). (fbb) Lateral (Mm. intertransversarii laterales). Short Muscles of the Neck. (Cf. Spalteholz, Fig. 341). Carefully clean the surface of the following muscles : (a) Larger posterior straight muscle of head (M. rectus capitis posterior major). (b) Lesser posterior straight muscle of head (M. rectus capitis posterior minor). (c) Superior oblique muscle of head (M. obliquus capitis superior). (d) Inferior oblique muscle of head (M. obliquus capitis inferior). DISSECTION OF THE HEAD AND NECK 235 Find the posterior ramus of the suboccipital nerve (ramus posterior N. suboccipitalis), the branches of which supply all four. Establish the origin, insertion, and action of each muscle. What are the boundaries of the " suboccipital space, or triangle'7? (Fig. 97.) Note in the space— (a) Posterior ramus of the first cervical nerve (N. sub occipitalis}. (b) Portion of the vertebral artery (A. vertebralis). Examine the floor of the space and distinguish— (a) Posterior arch of the atlas (arcus posterior atlantis). (b) Posterior atlanto-occipital membrane (membrana atlanto-occipitalis posterior). Blood-vessels and Nerves of Neck and Back. The more superficial vessels of the neck have already been studied. The student should carefully work out the following : Arteries. (Fig. 97.) (a) Occipital artery (A. occipitalis). How is it related to neighboring structures ? (aa) Muscular rami (rami musculares). To what muscles are these distributed? Note espe- cially the descending ramus (ramus descendens) (0. T. arteria princeps cervicis). (ab) Mastoid branch (ramus mastoideus). Into what foramen does this enter? (ac) Auricular branch (ramus auricularis ) . (ad) Occipital branches (rami occipitales) . (b) Ascending cervical artery (A cervicalis ascendens). (ba) Muscular branches (rami musculares). (bb) Deep ramus (ramus profundus). (c) Deep cervical artery (A. cervicalis profunda). With what vessels does this artery anastomose ? (d) Posterior ramus of highest intercostal artery (ramus posterior A. intercostalis supremae). (e) Posterior rami of intercostal arteries (rami posteriores Aa. inter- costalium). (ea) Muscular branches (rami musculares). (eb) Medial cutaneous rami (rami cutanei mediales). (ec) Lateral cutaneous rami (rami cutanei laterales). Veins. (a) Occipital vein (V. occipitalis). (aa) Mastoid emissary vein (emissarium mastoideum). Why are the emissary veins of special importance? Why is it a common practice to apply leeches and blisters behind the ear in certain intracranial affections? (b) Deep cervical vein (V. cervicalis profunda}. (c) Posterior rami of intercostal veins (rami posteriores Vv. intercos- talium). 236 LABORATORY MANUAL OF HUMAN ANATOMY (d) Posterior rami of lumbar veins (rami posterior es Vv. lumbalium). Nerves. In addition to those already studied note the following : (a) Posterior rami of cervical nerves (rami posterior es Nn. cervi- calium ) . (aa) Medial rami (rami mediales). (ab) Lateral rami (rami laterales). FIG. 97. Ramus descendens Ramus meningeus of the A. vertebralis Ramus mastoideu A. occipital! A. vertebralis - Proc. transversus attantis Posterior belly of the M. digastricus M. levator - scapulae M. semispinalis capitis M. semispinalis — cervicis Proc. spinosus vertebrae cervicalis VII. A. cervicalis profunda — A. transversa colli M. semispinalis — dorsi Rami occipitales of the A. occipitalis M. rectus capitis posterior minor . obliquus capitis superior Ramus occipitalis of the A. auricularis posterior — M. rectus capitis posterior major • Rami auriculares of the A. auricularis posterior Ramus muscularis of the A. vertebralis —A. vertebralis M. semispinalis capitis — Ramus profundus of the A. cervicalis ascendens M. semispinalis cervicis A. cervicalis profunda ". semispinalis cermcis Ranms dorsalis of the A. intercostalis suprema M. scalenus posterior .Ramus ascendens ] of the \ A. trans- .Ramus descendensl versa colli ..M. iliocostalis cervicis The arteries of the posterior region of the head and the deep arteries of the neck. (After Toldt, Anat. Atlas, Wien, 1900, 2 Aufl., p. 597, Fig. 972.) (b) Posterior rami of thoracic nerves (rami posterior es Nn. thora- calium ) . (ba) Medial rami (rami mediales) . (bb) Lateral rami (rami laterales). DISSECTION OF THE HEAD AND NECK 237 (c) Posterior rami of lumbar nerves (rami posteriores Nn. lum- balium ) . (ca) Medial rami (rami mediates) . (cb) Lateral rami (rami later ales). (d) Posterior rami of sacral and coccygeal nerves (rami posteriores Nn. sacralium et coccygei). Opening the Vertebral Canal. Carefully remove all muscles and tendons from the spinous processes and arches of the vertebrae from the occipital bone to the tip of the coccyx, avoiding injury, however, to the posterior rami of the spinal nerves (rami posteriores Nn. spinalium). Place high blocks under the thorax and let the head hang over the end of the table. The vertebral canal (canalis vertebralis) may be opened from behind in any one of four different ways: (a) with the double rhachiotome, (b) with a saw, (c) with mallet and chisel, (d) with bone-forceps. (a) With the Double Rhachiotome. — Place the saws of Luer's double rhachiotome on the cervical portion of the vertebral column; seize the handle with the right hand, pressing down from above upon the rhachi- otome with the left hand; saw (in the direction in which the teeth are set) with quick, rapidly repeated strokes through the vertebral arches. As soon as the saw has gone through, the same process is repeated a little lower down, and so on until the whole posterior wall of the vertebral column has been cut through as far as the last lumbar vertebra. Between the last lumbar vertebra and the sacrum cut through the ligamenta flava; introduce the vertebral forceps below the posterior arch of the last lumbar vertebra, seize hold of it and, grasping the forceps with both hands, tear away in one piece the whole posterior wall of the vertebral canal from the lumbar region to the occipital bone. If the cervical portion be not quite sawn through, apply the rhachiotome again and cut in a reverse direction. ( b ) With a Saw. — One may use a simple saw, cutting through first one side and then the other. The saw should pass close behind the articular processes and should be directed slightly obliquely, so that the cut passes a little medialward in the depth. It may be necessary to use the hammer and chisel also. Neelsen recommends the use of the " fox-tail saw." (c) With Mallet and Chisel— The vertebral arches may be chiselled instead of sawn through, if desired, but the tyro is apt to injure the cord. Special chisels (one for each side) are manufactured for the purpose, but a good heavy plain chisel works well. (d) With Bone-forceps. — Cut through the root of each vertebral arch (radix arcus vertebrae} (0. T. pedicle) on each side, just ventral to the superior articular processes, and thus remove the whole posterior wall of the vertebral canal. This method has the advantage that it opens up all intervertebral foramina and permits of the removal of the spinal ganglia and the proximal portion of each spinal nerve along with the spinal cord. 238 LABORATORY MANUAL OF HUMAN ANATOMY It will be well also to remove the posterior wall of the spinal canal in the sacrum and coccyx. The cord lying in its external covering, the dura mater, or pachymeninx spinalis, is now exposed. Notice the interspace between the third and fourth lumbar vertebrae. This is the site of Quincke 's ' ' lumbar puncture. ' ' Here a needle can be intro- duced into the cavum subarachnoideale during life without danger. Read carefully the description of the veins of the spinal column and study Spalteholz, Figs. 493 and 494. Examine carefully— (a) Spinal ramus of posterior ramus of each intercostal artery (ramus spinalis rami post. A. intercostalis) , passing through an interver- tebral foramen. (Cf. Spalteholz, Fig. 462.) (&) Spinal ramus of posterior ramus of each lumbar artery (ramus spi- nalis rami post. A. lumbalis). (c) Spinal rami of vertebral artery (rami spinales A. vertebralis) and the spinal rami of the ascending cervical artery (rami spinales A. cervicalis ascendentis ) . Spinal Meninges. (Fig. 98.) Clean the external surface of the dura mater, removing fat and areolar tissue. Lift the dura gently with fine forceps, and, with fine, sharp scissors, cut through the dura mater spinalis in the middle line .throughout its whole length. Take great care not to injure the spinal arachnoid (ar.achnoidea spinalis). Trace the terminal thread of the dura mater (filum durae mat r is spi- nalis) to its bony attachment. Note that the dura mater spinalis corresponds to the inner layer of the dura mater encephali, the outer layer having fused with the periosteum of the vertebral canal. The space (cavum epidurale) between the lining of the vertebral canal and the dura mater spinalis contains the plexus venosi, which in turn correspond to the cerebral sinuses. Note disproportion between the size of the cord and the size of the dura mater, especially in the regions where the mobility of the vertebral column is great. Observe the fibrous filaments from the anterior middle line of the dura which run obliquely down- ward ventralward to be inserted into the ligamentum longitudi- nale posterius; note their excessive development and fusion from the fourth lumbar vertebra downward; this is the liga- mentum sacrodurale anterius (ligament sacre anterieur of Tro- lard). (Cf. Poirier et Charpy, iii., Fig. 77.) What is its function? Note the dural sheaths of the nerve roots. DISSECTION OF THE HEAD AND NECK 239 Examine the membrane (arachnoidea spinalis) which bounds the cavum subdurale internally. Note that this is what many anatomists call the " visceral layer" of the arachnoid; below, at the summit of the conus terminal is (second sacral), it is re- flected upon the dura mater to form the " parietal layer " of the arachnoid; the " arachnoid cavity" of various writers is sit- Dura mater spinalis .Conus medullaris Arachnoidea spinalis Cavum subdurale Filum terminate ..7T^:Cavum subarachnoideale . Junction of arachnoidea and dura Filum terminale Arachnoidea spinalis xCavum subdurale Dura mater spinalis Disposition of the arachnoidea spinalis at the inferior extremity of the medulla spinalis. The sections are schematic (longitudinal and transverse). The pia mater is in red. The transverse section passes through the cauda equina. (From Poirier et Charpy, Traite d'Anat. hum., Paris, 1899, t. iii., 1, p. 118, Fig. 83.) uated between the parietal layer and the visceral layer, being the cavum subdurale of the present nomenclature. It is a serous cavity like the pleura. Can you separate the " parietal layer" from the dura! Do you see any blood-vessels in the " visceral layer"? Are there any calcified plates in the latter? Note the 240 LABORATORY MANUAL OF HUMAN ANATOMY prolongation of the arachnoid over the nerve roots and over the summits of the teeth of the liganientuin denticulatum. Lift the visceral layer of the arachnoid, cut through it with fine scissors, insert grooved director, and cut it open longitudi- nally a little to one side of median line. Examine the space (cavum subarachnoideale) beneath the visceral layer of the arachnoid and the pia mater. Note the expanse of the space especially in the region of the cauda equina, which it contains. FIG. 99. A Portions of the pars cervicalis of the spinal cord with nerve-roots. A, spinal cord seen from the ventral surface. On the right side the ventral fila radicularia have been cut through. S, spinal cord seen from the lateral surface.— 1, fissura mediana anterior ; 2, sulcus medianus posterior ; 3, sulcus lateralis ventralis, whence the ventral fila radicularia emerge ; 4, sulci laterales dorsales through which the dorsal root fibres enter the spinal cord ; 5, radix ventralis going past spinal ganglion cut through on the right side in Fig. A ; 6, radix dorsalis emerging from the ganglion spinale (&)• 7, N. spinalis immediately after its formation through the union of the radix ventralis and dorsalis dividing into 7, a ramus ventralis, and 7', a ramus dorsalis. The ramus com- municans and the ramus meningeus are not shown in this figure. (After Allen Thompson, from A. Rauber, Lehrbuch der Anatomie des Menschen, V. Aufl., Leipz., 1898, Bd. ii. S. 283, Fig. 248.) Where would the cerebrospinal fluid accumulate in greatest amount? Note precise spot where cavum subarachnoideale is tapped in Quincke's lumbar puncture. There is no communica- tion between the cavum subdurale and the cavum arachnoideale. Notice the areolar tissue everywhere present between the arach- noid and the pia. Make out the septum subarachnoideale pos- terius. Examine the spinal pia mater (pia mater spinalis). How DISSECTION OF THE HEAD AND NECK 241 closely does this membrane invest the cordf Note its extreme vascularity. What is meant by the term " lepto- meninx ' ' ? Study the lig amentum denticu- latum. Where is the medial border of the ligament inserted? On the lat- eral border note the teeth and the free arcades intermediate between the teeth. Into what are the summits of the teeth inserted! What is the rela- tion of the ligamentum denticulatum to the anterior and posterior roots? The number of teeth varies from eigh- teen to twenty-three. How many are there in your subject? What is the function of the ligament? Study the relations of the spinal nerve roots to the pia, the arachnoid, and the dura. (Cf. Poirier et Charpy, iii., Fig. 103.) The Spinal Nerves (Nervi spinales). (Figs. 99 and 100.) Count these on each side. Distin- guish the cervical nerves (Nn. cervi- cales, I -VIII.}, the thoracic nerves (Nn. thoracales, I.-XIL), the lumbar nerves (Nn. lumbales, I.-V. ) , the sacral Spinal cord in connection above with the medulla oblongata and pons. V, nervus trigeminus ; XII, nervus hypoglossus; C\, first cervical nerve ; C*2-8, second to eighth cervical nerve ; Tl-12, first to twelfth thoracic nerve ; L 1-5, first to fifth lumbar nerve ; S 1-5, first to fifth sacral nerve ; G, nervus coccygeus ; x, x, filum terminale of the spinal cord. From the root marked LI to x, cauda equina; Rr, plexus brachialis; CV, nervus femoralis ; Sc, nervus ischiadicus ; 0, nervus obtura- torius ; the enlargements opposite L 3, 4, and 5 represent the spinal ganglia on the dorsal roots. On the left side of the figure the sympathetic trunk is shown, a to as are ganglia; a, ganglion cervicale superius; & and c, ganglion cervicale medium et inferius; d, first thoracic ganglion; d', last thoracic ganglion ; I, first lumbar ganglion ; ss, first sacral ganglion. (After Allen Thompson, from A. Rauber, Lehrbuch der Anatomie des Menschen, V. Aufl., Leipz., 1898, Bd. ii. S. 504, Fig. 485. ) 16 FIG. 100. V »2 Rr 242 LABORATORY MANUAL OF HUMAN ANATOMY nerves (Nn. sacrales, L-V.), and the coccygeal nerve (N. coccy- geus}. Note the subdivision of each spinal nerve trunk into an anterior and a posterior ramus. Observe the roots of the spinal nerves (radices nervorum spinalium). Where does the ventral root (radix anterior) fuse with the dorsal root (radix poste- rior) 1 Note the ganglion (ganglion spinale) on the latter. What are the fila radicularia? Observe the relative lengths of the various nerve roots. How do you account for this? Which are the largest and which the smallest nerve roots? Examine the cauda equina carefully. How do the nerves leave and enter the vertebral canal ? Look for the ramus meningeus. Removal of Spinal Cord. Divide each spinal nerve trunk midway between the point of fusion of its two roots and the point of division into an anterior and a posterior ramus. Cut through the cord at the level of the first cervical nerve. Lift the cord and its membranes gently from the vertebral canal and transfer to formalin for subsequent study. THE SPINAL COED. Blood-vessels of the Spinal Cord. As a rule, special injections are necessary to demonstrate the blood-vessels of the cord well, but a good deal can be made out in ordinary cadavers. Study the following : Arteries. (a) Branches of vertebral artery (A. vertebralis). (aa) Spinal rami (rami spinales). (ab) Posterior spinal artery (A. spinalis posterior). (ac) Anterior spinal artery (A. spinalis anterior). (b) Branches of ascending cervical artery (A. cervicalis ascendens). (ba) Spinal rami (rami spinales). (c) Branches of highest intercostal artery (A. intercostalis suprema). (ca) Spinal rami (rami spinales). (d) Branches of intercostal arteries (Aa. intercostales) . (da) Spinal ramus of posterior ramus (ramus spinalis rami pos- terioris). (e) Branches of lumbar arteries (Aa. lumbales). (ea) Spinal ramus (ramus spinalis). (f) Branch of iliolumbar artery (A. iliolumbalis) . (fa) Spinal ramus (ramus spinalis). (g) Branches of lateral sacral artery (A. sacralis lateralis). (ga) Spinal rami (rami spinales). DISSECTION OF THE HEAD AND NECK 243 (For a description of the course of the vessels in the meninges and in the cord itself, see article " Spinal Cord" in last edition of Wood's Reference Hand-book of the Medical Sciences.) Veins. (a) Internal spinal veins (Vv. spindles internae). (b) Posterior external spinal veins (Vv. spinales externae posteriores) . (c) Anterior external spinal veins (Vv. spinales externae anteriores). (d) Intervertebral veins (Vv. intervertebrales) . External Morphology of Spinal Cord. What is the shape of the spinal cord! How is it curved? Note the position and extent of each of the following : (a) Cervical portion (pars cervicalis). (aa) Cervical enlargement (intumescentia cervicalis). (b) Thoracic portion (pars thoracalis) (0. T. dorsal portion). (c) Lumbar portion (pars lumbalis). (ca) Lumbar enlargement (intumescentia lumbalis). (d) Medullary cone (conus medullaris). (da) Swelling due to terminal ventricle (ventriculus terminalis). (e) Terminal thread (filum terminale). On the surface of the cord observe the following grooves : (a) Anterior median fissure (fissura mediana anterior). (b) Posterior median sulcus (sulcus medianus posterior). (c) Anterior lateral sulcus (sulcus lateralis anterior). (d) Posterior lateral sulcus (sulcus lateralis posterior). (e) Posterior intermediate sulcus (sulcus intermedius posterior) (0. T. paramedian furrow). (/) Anterior intermediate sulcus (sulcus intermedius anterior) (incon- stant). Between these grooves the funiculi of the spinal cord (funiculi medullae spinalis ) . (a) Anterior funiculus (funiculus anterior) (0. T. anterior column). (b) Lateral funiculus (funiculus lateralis) (0. T. lateral column). (c) Posterior funiculus (funiculus posterior) (0. T. posterior column). Transverse Sections of Spinal Cord. (Fig. 101.) Sections of the spinal cord (sectiones medullae spinalis) should next be studied. With a sharp, thin knife, cut through the cord transversely at the following levels: (1) just below roots of fourth pair of cervical nerves, (2) through middle of cervical enlargement, (3) through middle of thoracic cord, (4) through middle of lumbar enlargement, and (5) through conus terminalis. In the sections observe the differentiation into white matter (substantia alba) and gray matter (substantia grisea). 244 LABORATORY MANUAL OF HUMAN ANATOMY The Gray Matter. What is its form in cross-section? How does this vary at different levels? Localize the central canal (canalis centralis) FIG. 101. Cross-sections through the human spinal cord, stained with carmine. A, transverse section at the level of C iii : Cg, commissura grisea ; Ap, apex columnse dorsalis ; Ca, commissura ventralis alba ; Cc, canalis centralis ; Cm, commissura medullse spinalis ; Cm, cornu ven- trale; Crp, cornu dorsale; Fna, funiculus ventralis; FnB, fasciculus cuneatus Burdachi; FnG, fasciculus gracilis Golli ; Fnl, funiculus lateralis ; Fsla, flssura mediana ventralis ; Fslp, sulcus medianus dorsalis ; k, tractus solitarius ; Pr, formatio reticularis ; .Ra, radix ventralis ; Rp, radix dorsalis ; Sg, substantia gelatinosa Rolandi ; Sid, sulcus lateralis dorsalis ; Smd, septum medianum dorsale ; Spd, septum intermedium dorsale ; Til, tractus intennedio-lateralis. B, transverse section at the level of C vi : Prm, processus cervicalis medius cornu ventralis ; Til, columna intermedio-lateralis. C, trans- verse section at the level of T iii : CCl, nucleus dorsalis Clarkii. D, transverse section at the level of T xii : CCl, nucleus dorsalis. E, transverse section at the level of L v : m, medial cell group of the cornu ventrale ; Iv, lateral ventral, Id, lateral dorsal, and c, central cell group. F, transverse section at the level of S iii : m, medial, Id, lateral-dorsal cell group. G, transverse section through the lower part of the conus medullaris at the level of origin of the N. coccygeus. ( After H. Obersteiner, Anleitung beim Studium des Baues der nervosen Centralorgane im gesunden und kranken Zustande, III. Aufl., Leipz. u. Wien, 1896, S. 227, Figs. 96-102. ) and the gray matter close to it, the central gray substance (sub- stantia grisea centralis). In front of it is the anterior gray com- DISSECTION OF THE HEAD AND NECK 245 missure (commissura grisea anterior] and behind it the posterior gray commissure ( commissura grisea posterior) . Study in cross- section each of the following gray columns (columnae griseae) : (a) Anterior column of gray matter (columna anterior) (0. T. anterior horn). (6) Lateral column of gray matter (columna lateralis) (0. T. lateral horn). (ba) Reticular formation (formatio reticularis) . FIG. 102. .l.d. F.m.v. 5.U. N. Spinalis R.y. Schematic representation of the portion of a spinal cord corresponding to the attachment of the ventral and dorsal roots of one pair of spinal nerves. (From Barker, The Nerv. Syst., New York, 1901, PI. II. Fig. 2.) Black.— Cc., canalis centralis; C.d., commissura posterior (O.Y., commissura dorsalis) ; C.d.g., columna posterior (O.Y.,cornudorsalegriseum) ; C.v.g., columna anterior (O.Y.,cornuventralegriseum); Cm.v.a., commissura anterior alba (O.Y., com. ventralis alba) ; Cm.v.g., commissura anterior grisea (O.Y. com. ventralis grisea) ; Fc., funiculus cuneatus; Fg., funiculus gracilis; Fd., funiculus posterior (O.Y. funiculus dorsalis); FL, funiculus lateralis; Fv., funiculus anterior (O.Y., fun. ventralis); F.m.v., fissura mediana anterior (O.Y., fis. med. ventralis) ; G.sp., ganglion spinale ; R.d., radix posterior nervi spinalis (O.Y., rad. dorsalis) ; E.v., radix anterior (O.Y., ventralis) nervi spinalis (O.Y., rad. ventralis) ; S.I d., sulcus lateralis posterior (O.Y., sulc. lat. dorsalis) ; S.l.v., sulcus lateralis anterior (O.Y., sulc. lat. ventralis) ; S.i.d., sulcus intermedius posterior (O.Y., sulc. intermed. dorsalis) ; S.m.d., sulcus medianus posterior (O.Y., sulc. med. dorsalis.) Red.— Peripheral sensory neurones. The cell-bodies, 1, are situated in the spinal ganglion. The peripheral processes enter the peripheral nerves, the central axones pass by way of the radix posterior into the funiculus cuneatus of each side. There each axone bifurcates into an ascending and a descending limb, giving off also collaterals to the gray substance. Blue.— Lower motor neurones. The cell-bodies, 1, are situated in the columnae anteriores. They send their axones by way of the anterior roots into the peripheral nerves. The neural mechanism believed to form the basis of the simplest reflex arc is illustrated in the figure. (c) Posterior column of gray matter (columna posterior) (0. T. posterior horn). (ca) Neck of posterior column (cervix columnae posterioris) . (cb) Apex of posterior column (apex columnae posterioris). 246 LABORATORY MANUAL OF HUMAN ANATOMY (cc) Gelatinous substance of Rolando (substantia gelatinosa [Ro- (cd) Dorsal nucleus (nucleus dorsalis [Clarkii, Stillingi]) (0. T. Clarke's column). FIG. 103. Comma-shaped bundle Middle root-zone \ Posterior medial root-zone^ Radix posterior Lissauer's marginal zone (posterior lateral root-zone) Fasciculus cerebro- spinalis lateralis (pyramidalis lateralis)— Fasciculus cerebellospinalis Lateral limiting layer of the gray matter Bundle to lateral funicu- lusfrom Deiters's nucleus' and the red nucleus Fasciculus anterolateral superficialis [Gowersil] Corpora quadrigemina' (thalamus path) . Helweg's bundle Fila radicularia radicis anterioris Bundle connecting formatio reticularis with ' anterior funiculus (black : to the formatio / reticularis) Anterior marginal bundle (bundle to anterior funiculus from nucleus fastigii) / Commissural bundle Fasciculus gracilis [Golli] I Oval bundle of posterior funiculus (median root-zone) I I Ventral area of posterior funiculus (anterior root-zone) Stratum zonale (marginal zone) Substantia gelatinosa [Rolandi] Caput cplumnae posterioris (nucleus of the posterior horn) - Nucleus dorsalis [Stillingi, Clarkii] — Dorso- lateral Inter- mediate Ventral (ventrolateral and ventro- medial) Ganglion- cell groups of anterior horn Dorsomedial group of ganglion cells of anterior horn Fasciculus sulcpmarginalis (bundle from the superior colliculi of the corpora quadrigemina) Fasciculus cerebrospinalis anterior (pyramidalis anterior) Schematic transverse section of spinal cord with conduction paths and groups of ganglion cells. Magnification : circa 12.5 : 1 (Held). (All of the paths descending from the brain to the spinal cord are in colors ; all other paths in the spinal cord, ascending and descending, are indicated in black.) (After Spalteholz, Hand Atlas of Human Anatomy, Leipzig, 1903, vol. iii. p. 671, Fig. 749.) The White Matter. In the sections recognize in the white matter the position of each of the following : (a) In the anterior funiculus (funiculus anterior) : (aa) Anterior cerebrospinal or pyramidal fasciculus (fasciculus cerebrospinalis anterior [pyramidalis anterior]) (0. T. direct pyramidal tract). (ab) Proper anterior fasciculus (fasciculus anterior proprius [Flechsigi]) (0. T. anterior ground-bundle). (b) In the lateral funiculus (funiculus lateralis) : (ba) Lateral cerebrospinal or pyramidal fasciculus (fasciculus cerebrospinalis lateralis [pyramidalis lateralis]) (0. T. crossed pyramidal tract). (bb) Cerebellospinal fasciculus (fasciculus cerebellospinalis) (0. T. direct cerebellar tract of Flechsig).1 1 This would be better designated fasciculus spinocerebellaris dorsolateralis. DISSECTION OF THE HEAD AND NECK 247 (be) Superficial anterolateral fasciculus (fasciculus anterolateralis super ficialis [Gowersi]) (0. T. Gowers's tract). (bd) Proper lateral fasciculus (fasciculus lateralis proprius [Flechsigi]) (0. T. lateral ground-bundle). (c) In the posterior funiculus (funiculus posterior} : (ca) Slender fasciculus (fasciculus gracilis [Golli]) (0. T. column or tract of Goll). (cb) Wedge-shaped fasciculus (fasciculus cuneatus [Burdachi]) (0. T. column or tract of Burdach). (d) Anterior white commissure (commissura anterior alba). FACE. Surface Anatomy. The general features of the surface have already been exam- ined. The student will do well at this time to make especial drawings of the external appearance of the eye and mouth- opening. The Eye. Indicate the eyebrow (superdlium) , with the hairs (super- cilia). Examine the lids (palpebrae), closed and open. After noting the appearance of the anterior surface (fades anterior palpebrarum) , evert each lid and view the posterior surface (fades posterior palpebrarum). The slit between is called the palpebral fissure (rima palpebrarum). At the junction of the two lids are situated the medial and lateral palpebral commis- sures (commissurae palpebrarum lateralis et medialis) (0. T. external and internal canthi). These are at the lateral and medial angles of the eye (anguli oculi lateralis et medialis). Observe that the edge of each lid has two margins (limbus palpe- bralis anterior, — posterior). What is the relation of the eye- lashes (dlia) and of the openings of the Meibomian follicles (glandulae tar sales [Meibomi]) to these margins? Trace the continuity of the palpebral conjunctiva (tunica conjunctiva palpebrarum) with the bulbar conjunctiva (tunica conjunctiva bulbi). Note the recesses in the region where the palpebral con- junctiva is reflected upon the eyeball; these are the superior and inferior fornices (fornix conjunctivae superior, — inferior). Observe the triangular space (lacus lacrimalis) at the medial extremity of the rima palpebrarum; in its centre is a reddish flesh-like mass, the lacrimal caruncle (caruncula lacrimalis). Observe the small vertical semilunar fold of conjunctiva (plica semilunaris conjunctivae) just lateral from the caruncle. It cor- 248 LABORATORY MANUAL OF HUMAN ANATOMY responds to the third eyelid, or membrana nictitans, of lower animals. The stream (rivus lacrimalis) of tears (lacrimae) run- ning over the conjunctiva passes to the medial angle of the eye. At the point on each lid where the eyelashes cease is a small eminence, the lacrimal papilla (papilla lacrimalis). These eminences are perforated, the openings looking like two minute black dots (puncta lacrimalia) . The openings lead into small canals, lacrimal ducts (ductus lacrimales). Pass a fine bristle into each. The lacrimal apparatus will be further studied later. The Mouth-opening. Note that it is bounded by the two lips (labia on's), one supe- rior (labium superius), one inferior (labium inferius). At the junction of the lips at the two angles of the mouth (anguli oris) are the commissures of the lips (commissurae labiorum). The slit between the lips is called the rima oris. Note the curious transition between skin and mucous membrane in the lip. Skin and Superficial Fascia. Observe the thinness and fineness of the skin of the face. Compare its mobility with that of other parts. Which portions are most firmly attached to subjacent structures? Are any comedones visible! Note the distribution of the hairs of the beard (barba). Observe the long, rather stiff hairs at the nose openings (vibrissae). Through the skin feel the external maxil- lary artery where it passes over the margin of the mandible. Distend the cheeks and lips with moist cotton and stitch the margins of the lips together with a fine needle. Make an incision through the anterior median line and re- move the skin of the face, taking no fat with it. Avoid injury to the upper part of the platysma, the M. risorius, and the struct- ures of the eyelids. After the platysma has been carefully studied, it may be removed. Cutaneous Muscles of Face. (Vide Fig. 104.) Note that the majority of the muscles of the face and scalp have attachments to the skin; indeed, these muscles have been derived by progressive differentiation of a primitive cervico- f acial cutaneous muscle ; all of them are innervated by branches of the N. f acialis, which is the nerve of the hyoid arch. Observe the tendency to a grouping around various orifices, the muscles acting as dilators or constrictors of these orifices. What part do these muscles play in facial expression? DISSECTION OF THE HEAD AND NECK 249 Platysma. Muscles of the external ear. (a) M. auricularis anterior (already studied). (b) M. auricularis posterior (already studied). (c) M. auricularis superior (already studied). Muscles of the eyelids. Dilators. (a) M. epicranius (already studied). Note that the principal dilator, the M. levator palpebrae superioris, is not a skin-muscle. FIG. 104. Pericranium^ M. orbicularis oculi (parsorbitalis) M. corrugator supercilii.. M. orbicularis oculi (pars palpebralis) Ltg. palpebrale mediate M. procerus M. quadra- tus labii superioris M. auricularis superior M. auricularis anterior Caput angulare Caput infra- orbitale ... M. caninus M. zygomaticus M. risorius — M. triangularis > Platysma M. quadratus labii inferioris M. transversus menti ( Var. The muscles of the face. (After Toldt, Anat. Atlas, Wien, 1900, 2 Aufl., p. 296, Fig. 537.) Constrictors. (a) Procerus ("prolonged") muscle (M. procerus) (0. T. pyramid alis nasi). This muscle is wrongly classed as a part of the M. frontahs. Comparative anatomy has shown it to have been derived from the muscle which lifts the lip. Note that the M. procerus is an antagonist of the M. frontalis. (b) Orbicular muscle of eye (M. orbicularis oculi) (0. T. orbiculan palpebrarum). (ba) Palpebral part (pars palpebralis). 250 LABORATORY MANUAL OF HUMAN ANATOMY (baa) Medial palpebral ligament (ligamentum palpe- brale mediale). (bab) Lateral palpebral raphe (raphe palpebralis lat- (bb) Orbital part (pars orbitalis). (be) Lacrimal part (pars lacrimalis [Horneri]). (c) Corrugator muscle (M. corrugator). Note the relation of the muscle to physical or mental effort. Muscles of the nose. Dilators. (a) Transverse part of nasal muscle (pars transversa M. nasalis). Note the origin on the back of the nose and insertion into skin of nasolabial groove — not jugulum alveolare of upper canine tooth. It is called the " muscle of sensuality." (b) Dilator muscle of nose (M. dilator naris). (c) Angular head of quadrate muscle of upper lip (caput angular e M. quadrati labii superioris) (0. T. superficial elevator of lip). (d) Infraorbital head of quadrate muscle of upper lip (caput infra- orbit. M. quadrat, labii superioris) (0. T. deep elevator of upper lip). Constrictors. (a) Alar part of nasal muscle (pars alaris M. nasalis) (0. T. de- pressor alae nasi). (b) Depressor muscle of septum (M. depressor septi). (c) Triangular muscle of nose (M. triangularis nasi). Muscles of the lips. Dilators of mouth. Group 1. (a) Muscle of laughing (M. risorius). (b) Zygomatic muscle (M. zygomaticus) (muscle of grimace). Group 2. (c) Quadrate muscle of upper lip (M. quadratus labii superioris). (ca) Zygomatic head (caput zygomaticum) (0. T. zygomati- cus minor). (cb) Infraorbital head (caput infraorbitale) (0. T. levator labii superioris). (cc) Angular head (caput angular e) (0. T. superficial ele- vator of lip, or levator labii superioris alaeque nasi). Group 3. (d) Canine muscle (M. caninus) (muscle of menacing hate) (0. T. levator anguli oris). (e) Triangular muscle of mouth (M. triangularis oris) (muscle of sadness) (0. T. depressor anguli oris). Group 4. (/) Quadrate muscle of lower lip (M. quadratus labii inferioris) (0. T. depressor labii inferioris). (g) Chin muscle (M. mentalis) (muscle of hesitation, doubt, dis- dain, disgust). Group 5. (h) Cheek muscle (M. buccinator) (muscle of suckling; trumpet- blower's or glass-blower's muscle). DISSECTION OF THE HEAD AND NECK 251 (ha) Buccopharyngeal fascia (fascia buccopharyngea) . In cleaning this muscle avoid injury to the motor branch from the N. facialis and the sensory buc- cinator nerve from the N. trigeminus. Constrictors of mouth. (a) Orbicular muscle of mouth (M. orbicularis oris). As a muscle of vegetable life it closes the mouth to hinder exit of saliva and food, prevents entrance of foreign bodies, is prehensile in taking food and liquid, and is active in suction and mastication; as a muscle of relational life it closes lips partly or completely in physical effort, in articulation of words, whistling, playing musical instruments, kissing, etc. Note the division into a pars externa and a pars interna. The latter is unaffected in cerebral hemiplegia, and the patient can still close the mouth, whistle, and speak. Both are affected in glosso-labio-laryngeal paralysis, and the patient can no longer whistle, retain saliva, or pronounce the letters o and u. (b) Compressor muscle of lips (M. compressor labiorum [Kleinii]) (0. T. rectus labii of Aeby). (c) Incisive muscle of upper lip (M. incisivus labii superioris). (d) Incisive muscle of lower lip (M. incisivus labii inferioris). The incisive muscles act along with the M. orbicularis oris in pointing the mouth : they are sometimes called the " muscles of pouting." Eeferences. 1. On the origin of the facial muscles : Gegenbaur, C., Lehrbuch der Anatomic des Menschen. Ruge, Untersuchungen iiber die Gesichtsmuskulatur der Primaten, Leipzig, 1887. 2. On the muscles as agents of expression : Bell, C., Anatomy and Physiology of Expression, 1844. Duchenne (of Boulogne), Mecanisme de la physionomie humaine, 1852. Darwin, C., Expression of Emotions in Man and Animals. Region of Parotid Gland. In the study of the deep cervical fascia the parotideomasse- teric fascia (fascia parotideomasseterica) has been observed passing upward to become attached to the zygoma. On its sur- face the ramus anterior of the N. auricularis magnus was noted. The fascia is to be very carefully removed and the parotid gland defined. Observe the exact position and relations of the parotid gland (glandula parotis). Find its excretory duct (ductus parotideus [Stenonis] ) and follow it throughout its course. Cut into it and pass a probe through into the mouth. Note the position of the oral termination of the duct. In relation to the upper border of the duct, note the accessory parotid gland (Gl. parotis accesso- LABORATORY MAXUAL OF HUMAN ANATOMY ria) (O. T. socia parotidis). Follow the retromandibular proc- ess of the gland (processus retromandibularis) in behind the mandible. How is the pocket in which the parotid gland is con- tained separated from that in which the subniaxillarv gland is situated? Pick away the parotid gland bit by bit, in order to study the blood-vessels and nerves of the region, many of which pass directly through the gland-substance. Superficial Blood-vessels and Nerves of Face. (Vide Figs. 87. 873, and 105.) Arteries. (a) External carotid (A. carotis externa). (aa) Superficial temporal (A. temporalis superficial). (aaa) Parotid rami (rami parotidei). (aab) Transverse artery of face (A. transversa faciei). (aac) Anterior auricular rami (rami auricula res ante- riores). (aad) Middle temporal artery (A. temporalis media). (aae) Zygomatico-orbital artery (A. zygomatico-orbi- talis). The terminal rami have already been studied in the dissection of the scalp. (ab) Internal maxillary artery (A. maxittaris interna). Its branches cannot yet be seen. (ac) External maxillary artery (A. maxiOaris externa) (O. T. facial artery). (oca) Inferior labial (A. labialis inferior). (atA) Superior labial (A. labial is superior), (ace) Angular artery (A. angularis). Veins. (Cf. Spalteholz, Figs. 487, 488.) (a) Posterior facial vein (V. facialis posterior). (aa) Superficial temporal vein (V. temporalis superficialis) . (ab) Middle temporal vein (V. temporalis media). (ac) Anterior auricular veins (Ft?, auriculares anteriores). (ad) Posterior parotid veins (Vv. parotideae posteriores). (ae) Transverse vein of face (V. transversa faciei). (b) Anterior facial vein (V. facialis anterior). (ba) Angular vein (V. angularis). (baa) Frontal vein (V. frontalis). (bab) Supraorbital vein (V. supraorbitalis). (bac) Nasofrontal vein (V. nasofrontalis). (bad) External nasal veins (Vv. nasales externae). (bae) Veins of the lips (Vv. labiates superior et infe- rior). (baf) Anterior parotid veins (Vv. parotideae ante- riores). (bag) Masseteric veins (Vv. massetericae) . Nerves. Cut away free projecting part of proeessus mastoideus, with saw OX OF THE HEAD AXD XECK FIG. 105. Kami temporales soperficiales of the X. aoriculo- temporalis Xn. auriculares anteriores X. auriculo- temporalis Branches of the X. occipi- talis major Kami tonporales of the X. facialis Bami zygomatici of the X. :.. :=.!:- 4is externus - of the N. ethmoid- •tti ••MB '>:•- cipitalis X. auricularis posterior RMBBBdtoM Kami naaales ex tern i of the X. infraorbi- talis X. occipitalis minor X. auricularis magnns / X. hypogloasos / Ramos colli X. cutaneus colli AnsacervicalissoperficialiB The distribution of the facial, auriculotemporal. great auricular, greater and nerves and their communicatk muscle of the eye, the frontal muscle, and the platysma. p. S71, Fig. 1314.) occipital 254 LABORATORY MANUAL OF HUMAN ANATOMY first and chisel afterwards. Do not injure N. auricularis poste- rior. (a) Anterior ramus of N. auricularis magnus (ramus anterior N. auricularis magni). (b) Branches of facial nerve (N. facialis). (Vide Fig. 105.) (ba) Parotid plexus (plexus parotideus). (bb) Temporal rami (rami temporales). (be) Zygomatic rami (rami zygomatici). (bd) Buccal rami (rami buccales). (be) Ramus of margin of jaw (ramus marginalis mandibulae). Examine also — (bf) Digastric ramus (JR. digastricus) . (bfa) Stylohyoid ramus (R. stylohyoideus). (bfb) Ramus anastomosing with glossopharyngeal nerve (ramus anastomoticus cum N. glossopharyngeo}. (c) Branches of trigeminal nerve (N. trigeminus). (ca) Branches of ophthalmic nerve (N. ophthalmicus) . (caa) Branches of frontal nerve (N. frontalis). (caaa) Supraorbital nerve (N. supraorbitalis) . (caab) Frontal ramus (ramus frontalis). (caac) Supratrochlear nerve (N. supratroch- learis). (cab) Branches of nasociliary nerve (N. nasociliaris) . (caba) One of anterior nasal rami (rami na- sales anteriores). (cabaa) External nasal ramus (ramus nasalis externus). (cac) Branches of infratrochlear nerve (N. infratroch- learis). (caca) Superior palpebral ramus (ramus palpe- bralis superior). (cacb) Inferior palpebral ramus (ramus palpe- bralis inferior). (cb) Branches of the maxillary nerve (N. maxillaris) (0. T. superior maxillary). (cba) Branches of zygomatic nerve (N. zygomaticus). (cbaa) Zygomaticotemporal ramus (ramus zy- gomaticotemporalis) . (cbab) Zygomaticofacial ramus (ramus zygo- matico facialis). (ebb) Branches of infraorbital nerve (N. infraorbitalis) . (cbba) Inferior palpebral rami (rami palpe- bralesjnferiores). (cbbb) External nasal rami (rami nasales ex- terni) . (cbbc) Superior labial rami (rami labiales supe- rior es ) . (cc) Branches of the mandibular nerve (N. mandibularis) (0. T. inferior maxillary). (cca) Branch of masticatory nerve (N. masticatorius) . DISSECTION OF THE HEAD AND NECK 255 (ccaa) Buccinator nerve (N. buccinatorius) (0. T. long buccal). (ccb) Auriculotemporal nerve (N. auriculotemporalis) . (ccba) Parotid rami (rami parotidei). (ccbb) Anastomotic branch of facial nerve (ramus anastomoticus cum N. fa- cialis). (ccbc) Anterior auricular nerves (Nn. auricu- lares anteriores). (ccbd) Superficial temporal rami (rami tem- porales superficiales) . (ccc) Mental nerve (N. mentalis). (ccca) Mental rami (rami mentales). (cccb) Inferior labial rami (rami labiales infe- riores), Eyelids. (Figs. 106 and 107.) Dissect up the M. orbicularis palpebrarum in its entirety and reflect it medialward, avoiding injury to the underlying vessels and nerves. Study— (a) Orbital septum (septum orbitale) (0. T. palpebral ligaments). Note its attachments. (b) Tarsi. (ba) Upper tarsus (tarsus superior). (bb) Lower tarsus (tarsus inferior). How do these differ? (c) Tarsal glands (glandulae tarsales [Meibomi]) (0. T. Meibomian glands). Compare those of the upper with those of the lower lid. Exam- ine the orifices with a hand lens along the limbi palpebrales poste- riores. Squeeze the lid between the thumb and finger, so as to express some of the greasy secretion (sebum palpebrale). (d) Lateral palpebral raphe (raphe palpebralis lateralis) (0. T. external tarsal ligament). Examine its attachments to the os zygomaticum and to the tarsi. (e) Medial palpebral ligament (ligamentum palpebrale mediale) (0. T. internal tarsal ligament). Examine its attachments to the maxilla and to the tarsi. (f) Nerves and blood-vessels of the lids. These have been enumerated above in connection with the arteries, veins, and nerves of the face. (g) Tendon of insertion of the M. levator palpebrae superioris. This can be exposed by cutting transversely through the upper part of the septum orbitale close to the bone and reflecting it downward towards the tarsus superior. • Lacrimal Apparatus (Apparatus lacrimalis). Dissect out the upper and lower lacrimal glands (glandula lacrimalis superior, — inferior). Are any accessory lacrimal 256 LABORATORY MANUAL OF HUMAN ANATOMY Insertion of the tendon of the M. rectus superior Fascia muscularis Expansion of the ten- don of the M. leva- tor palpebrae superioris M. orbicularis oculi , Margosupraorbitalis Septum orbitale _ Fornix conjunctivae- superior Lens crystal lina-- Cornea Conjunctiva bulba Tarsus inferior Conjunctiva palpe-' brarum Fornix conjunctivae inferior M. obliquus inferior Insertion of the tendon of the M. rectus inferior FIG. 106. Spatium interfasciale (Tenoni) ,' Fascia bulbi (Tenoni) Periorbita | M. levator palpebrae superioris ; I M. rectus superior • / Corpus adiposum orbitae Foramen opticum Processus clinoideus anterior. '__ A. carotis interna . Sinus sphenoidalis -- N. opticus M. rectus inferior Sinus maxillaris Paries inferior orbitae \ Fascia bulbi (Tenoni) Sclera The capsule of Tenon (fascia bulbi) and its relation to the tendons of the superior and inferior straight muscles (Mm. rectus superior and rectus inferior). (After Toldt, Anat. Atlas, Wien, 1903, 3 Aufl p. 907, Fig. 1378.) FIG. 107. Septum orbitaleC Sutura zygomaticomaxillaris N. supraorbitalis ,_.Ramus frontalis |_ ..N. supratrochlearis - -c— -Tarsus superior "' f _\ Lig. palpebrale mediale /"~/ — Processes frontalis maxiUae ""* Tarsus inferior N. infraorbitalis The orbital septum (septum orbitale) and the tarsal cartilages. The skin and orbicular muscle of have been removed. ( After Toldt, Anat. Atlas, Wien, 1903, 3 Aufl., p. 909, Fig. 1385. ) DISSECTION OF THE HEAD AND NECK 257 glands (Gl. lacrimales accessoriae) present? Underneath the gland find the minute excretory ducts (ductuli excretorii GL lacrimalis). About how many are there ? Where do they open! Reflect the ligamentum palpebrale mediale and expose the ampulla ductus lacrimalis and the lacrimal sac (saccus lacri- malis}. Note its summit (fornix sacci lacrimalis} and the duct leading from it down into the nose (ductus nasolacrimalis} . (Fig. 108.) FIG. 108. Papillae lacrimales with the puncta lacrimalia Plica semilunaris — - -- conjunctivae Saccus lacrimalis Crista lacrimalis posterior -~ .:;:,: M. obliquus inferior -' ' Ductus nasolacrimalis •'"' Sinus maxillaris "" Ampulla ductus lacrimalis Lacus lacrimalis (tear lake) Fornix sacci lacrimalis \---Lig. palpebrale mediale ( turned back ) --(Jrista lacrimalis aiitn-inr Caruncula lacrimalis Mucous membrane of the nasal cavity (laid bare from the outside) Lower end of the ductus nasolacrimalis The tear sac (saccus lacrimalis), the lacrimal canals (ductus lacrimales), and the nasolaerinwl duct (ductus nasolacrimalis). Part of the maxilla has been removed. (After Toldt, Anat. Atlas, Wien, 1903, 3 Aufl., p. 912, Fig. 1391. ) Divide the lids vertically through the middle and turn the medial halves of the lids upward and downward respectively. Dissect away the conjunctiva at the medial angle of the eye and expose the superior tarsal muscle (M. tarsalis superior} and the inferior tarsal muscle (M. tarsalis inferior} (0. T. tensor tarsi). Note the relation of the saccus lacrimalis to the tarsal muscles on one hand and to the medial palpebral ligament on the other. What is the action of the tarsal muscles? Nose. At this stage the nasal bones (ossa nasalia} and cartilages (cartilagines nasi} may be conveniently examined. Dissect out and study the following: (a) Lateral cartilage of nose (cartilago nasi lateral is}. (b) Cartilage of septum of nose (cartilago septi misi) (anterior margin ). 17 258 LABORATORY MANUAL OF HUMAN ANATOMY (c) Larger alar cartilage (cartilago alaris major). (ca) Lateral crus (cms laterale). (cb) Medial crus (crus mediale). (d) Lesser alar cartilages (cartilagines alares minores). Are any sesamoid cartilages present f External Ear, or Auricle. (Fig. 109.) Though the auricle (auricula) (0. T. pinna) belongs to the cranium rather than to the face, it can be most conveniently dissected at this stage. FIG. 109. Helix Fossa triangularis Crura anthelicis Anthelix Scapha Concha auri- culae Cymba x conchae Cavum.N conchae ? Incisura anterior, Meatus auditorius externus. Tragus - y| Incisura intertragica ''I Lobulus auriculae helicis \ Sulcus auriculae posterior Antitragus The external ear (auricula) of a young woman. (After Toldt, Anat. Atlas, Wien, 1903, 3 Aufl., p. 920, Fig. 1406.) Make a careful drawing first of the lateral surface, then of the medial surface. Indicate- On the lateral surface — (a) Lobule of auricle (lobulus auriculae). (b) Tragus (tragus). (ba) Hairs of tragus (tragi). (c) Cartilage of antitragus (antitragus) . (d) Intertragic notch (incisura intertragica). (e) Anterior notch (incisura anterior). (f) Concha of auricle (concha auriculae). (fa) Cymba of concha (cymba conchae) (" boat of the concha"). (fb) Cavity of concha (cavum conchae). (g) Coil (helix). (ga) Crus of coil (crus helicis). DISSECTION OF THE HEAD AND NECK 259 (gb) Spine of coil (spina helicis). (gc) Tail of coil (cauda helicis). (h) Anthelix (anthelix). (ha) Crura of anthelix (crura antheUcis). (i) Triangular fossa (fossa triangularis). (j) Tubercle of auricle (tuberculum auriculae [Darwini]), if present. On the medial surface — (a) Fossa of anthelix (fossa antheUcis). (b) Eminence of concha (eminentia conchae). (c) Eminence of scapha (eminentia scaphae). (d) Eminence of triangular fossa (eminentia fossae triangularis). Eemove the skin from the whole auricle, taking care not to injure the minute muscles and ligaments beneath. Isolate the latter. FIG. 110. M. auricularis posterior M. transversus auriculae M. obliquus auriculae M. auricularis superior M. auricularis anterior (profundus) The muscles on the medial surface of the cartilage of the ear. Left ear. (After Toldt, Anat. Atlas, Wien, 1903, 3 Aufl., p. 921, Fig. 1413.) Muscles. (a) Larger muscle of helix (M. helicis major). (b) Smaller muscle of helix (M. helicis minor). (c) Muscle of tragus (M. tragicus). (d) Pyramidal muscle of ear (M. pyramidalis auriculae [Jungi]). (e) Muscle of antitragus (M. antitragicus) . (f) Transverse muscle of ear (M. transversus auriculae). (g) Oblique muscle of auricle (M. obliquus auriculae). (h) Muscle of notch of helix (M. incisurae helicis [Santorini]) . Ligaments. (a) Auricular ligaments (ligamenta auricularia [Valsalvae]). (aa) Anterior auricular (Lig. auriculare anterius). (ab) Superior auricular (Lig. auriculare superius). (ac) Posterior auricular (Lig. auriculare posterius). 260 LABORATORY MANUAL OF HUMAN ANATOMY Cut the auricle off close to the skull ; macerate the cartilages and scrape clean. Study the following: (a) Isthmus of cartilage of ear (isthmus cartilaginis auris). (b) Terminal notch of ear (incisura terminates auris). (c) Antitragohelicine fissure (fissura antitragohelicina). (d) Transverse anthelicine groove (sulcus anthelicis trans versus). (e) Groove of sulcus of crus (sulcus cruris helicis). TEMPORAL REGION AND RETROMANDIBULAR FOSSA. Clean away the superficial fascia and expose the deep fascia above the zygomatic process. Preserve the arteries, veins, and nerves on its surface, and watch especially for blood-vessels and nerves perforating the fascia. Temporal Fascia. The temporal fascia (fascia temporalis) should now be studied. What are its attachments? Demonstrate the two lay- ers below. What structures perforate the fascia? Trace the peripheral distribution of the following : (a) Zygomaticotemporal ramus of facial nerve (ramus zygomaticotem- poralis N. facialis) (0. T. temporal branch of temporomalar). (b) Temporal rami of facial nerve (rami temporales N. facialis). (c) Zygomaticofacial ramus of zygomatic nerve (ramus zygomaticofa- cialis N. zygomatici). Follow the middle temporal artery (A. temporalis media] from its origin from the A. temporalis superficialis to the point where it pierces the fascia. Masseter Muscle. The masseter muscle (M. masseter) may now be dissected out. Divide the N. facialis below the ear and throw it forward. If the other structures superficial to the M. masseter impede the dissection, they may also be reflected. Study the form, position, origin, and insertion of the muscle. Cut through the fascia tem- poralis just above the processus zygomaticus and reflect it upward, saving the vessels and nerves which pass through it. Cut through the bony arch of the zygoma in front of and behind tlie^ origin of the M. masseter. The anterior saw-cut must be obliquely made. Throw the bony arch with the M. masseter DISSECTION OF THE HEAD AND NECK 261 lateralward and downward and find the artery (A. masseterica) and nerve (N. massetericus, V. 3) passing through the incisura mandibulae (0. T. sigmoid notch) to it. Cut through these after they have been cleaned and studied, but do not detach the M. masseter from its insertion. Temporal Muscle. The temporal muscle (M. temporalis) may now be examined. How are the fibres arranged ! Saw nearly through the coronoid process of the mandible, making the cut pass obliquely from the middle of the incisura mandibulae downward and forward to the junction of the ramus with the basis mandibulae. Complete the division with fine forceps. Avoid injury to the N. buccinatorius. Reflect the processus coronoideus with the attached M. tempo- ralis upward and separate the muscle from the bone. Study the anterior and posterior deep temporal nerves (N. temporalis profundus anterior — posterior] and arteries (A. temporalis prof undo, anterior — posterior) ; follow the distribution of the A. temporalis media; find the point of exit of the ramus zygo- maticotemporalis N. zygomatici (0. T. temporal branch of tem- poromalar). Pterygoid Region. Make a cut through the neck of the condyloid process of the mandible and another transversely through the ramus man- dibulae just above the level of the mandibular foramen (O. T. inferior dental foramen). Begin the cuts with the saw and complete with bone-forceps. Eemove the incised portion of the ramus and dissect away the fat and areolar tissue, so as com- pletely to expose the pterygoid muscles and the pterygoman- dibular raphe (raphe pterygomandibularis) of the fascia bucco- pharyngea. Examine carefully the following structures : Muscles. (Spalteholz, Figs. 294 and 295.) (a) External pterygoid (M. pterygoideus externus). (b) Internal pterygoid (M. pterygoideus internus). (c) Buccinator muscle (M. buccinator). (ca) Buccopharyngeal fascia (fascia buccopharyngea) with its raphe pterygomandibularis. Arteries. (Vide Spalteholz', Fig. 439.) (a) Internal maxillary (.4. maxillaris rntrrna). First portion. (an) Deep auricular (.1. auricularis profunda}. (ab) Anterior tympanic (A. tympanica anterior). 262 LABORATORY MANUAL OF HUMAN ANATOMY (ac) Inferior alveolar (A. alveolaris inferior) (0. T. inferior dental). (aca) Mylohyoid ramus (ramus mylohyoideus). Second portion. (ad) Middle meningeal (A. meningea media). (ada) Accessory meningeal ramus (ramus meningeus ac- cessorius) (0. T. small meningeal). (ae) Masseteric (A. masseterica) . (af) Posterior and anterior deep temporal (Aa. temporales pos- terior et anterior profundae). (ag) Pterygoid rami (rami pterygoidei). (ah) Buccinator (A. buccinatoria) (0. T. buccal). (ai) Posterior superior alveolar (A. alveolaris superior poste- rior) (0. T. posterior dental). Third portion. It cannot be studied at this stage of the dissection. Veins. These are seldom well enough preserved to be studied in the dissec- tion satisfactorily. Atlases illustrating the part and, if possible, museum preparations of special venous injections, should be con- sulted. Tributaries of the posterior facial vein (V. facialis posterior). (a) Articular mandibular veins (Vv. articulares mandibulares) . (b) Stylomastoid vein (V. stylomastoidea) . (c) Pterygoid plexus (plexus pterygoideus). (ca) Middle meningeal veins (Vv. meningeae mediae). (cb) Deep temporal veins (Vv. temporales profundae). (cc) Masseteric veins (Vv. massetericae) . (cd) Inferior alveolar vein (V. alveolaris inferior) (0. T. in- ferior dental). (d) Transverse vein of face (V. transversa faciei). Joint of Jaw. The jaw-joint (articulatio mandibularis) (0. T. temporomax- illary articulation) should now be studied. What bony surfaces enter into its formation? Examine — • (a) Joint-capsule (capsula articularis) (0. T. capsular ligament). (b) Joint-disk (discus articularis) (0. T. interarticular fibrocar- tilage). (c) Temporomandibular ligament (ligamentum temporomandibu- lare) (0. T. external lateral ligament). (d) Sphenomandibular ligament (ligamentum sphenomandibulare) (0. T. internal lateral ligament). (e) Stylomandibular ligament (ligamentum stylomandibulare) (0. T. stylomaxillary ligament). DISSECTION OF THE HEAD AND NECK 263 Nerves of Pterygoid Region. To see these well the joint of the jaw should be opened and the condyloid process together with the M. pterygoideus externus turned forward. Avoid the N. auriculotemporalis. (a) Mandibular nerve (N. mandibularis) (0. T. inferior maxillary division of the trigeminal nerve), (aa) Spinosus nerve (N. spinosus) (0. T. recurrent nerve). N. temp. prof. post..-> Ramus meningeus_ . . N. auriculotetnp.. N. facial Chorda tympani . . ,!T FIG. 111. N. temporalis profundus medius I .N. ophthalmicus r.. — N. maxillaris .N. temporalis profundus anterior N". pterygoideus exterior X. massetericus N. buccinatorius .--N. lingualis N. alveolaris inferior . . N. mylohyoideus. Ramus digastricus Ramus anast. cum N. hypoglosso Plexus dentalis inferior N. mentalis i Diagram of the N. mandibularis. (From Poirier et Charpy, Trait6 d'Anat. hum., Paris, 1899, t. in., 3, p. 824, Fig. 463.) (ab) Masticator nerve (N. masticatorius) . (aba) Masseteric nerve (N. massetericus). (abb) Anterior and posterior deep temporal nerves (Nn. temporales profundi anterior et posterior). (abc) Buccinator nerve (N. buccinatorius). (abd) External pterygoid (N. pterygoideus externus). (abe) Internal pterygoid (N. pterygoideus internus). (ac) Auriculotemporal nerve (N. auriculotemporalis). (aca) Nerve of external auditory meatus (N. meatus au- ditorii externi). (acaa) Branch to tympanic membrane (ramus membranae tympani). 264 LABORATORY MANUAL OF HUMAN ANATOMY The other branches have been already studied, viz. — (acb) Parotid rami (rami parotidei). (ace] Anastomotic with the facial (rami anastomotici cum N. faciali). (acd) Anterior auricular (Nn. auriculares anteriores). (ace) Superficial temporal rami (rami temporales super- ficiales ) . (ad) Lingual nerve (N. lingualis) (branches studied later). (ae) Inferior alveolar nerve (N. alveolaris inferior) (0. T. in- ferior dental). (aea) Mylohyoid nerve (N. mylohyoideus) . Other branches studied later. (b) Chorda tympani of N. intermedius. (c) Otic gangiion (ganglion oticum). This can be exposed now, but can be better studied later. Mandibular Canal. The mandibular canal (canalis mandibularis) (0. T. inferior dental canal) is somewhat difficult to open. With Hey's saw, mallet and chisel, and bone-forceps remove the outer compact layer of the mandible so as to expose the con- tents of the canal. Study the following: (a) Inferior alveolar artery (A. alveolaris inferior) (0. T. inferior dental). (aa) Mylohyoid ramus (ramus mylohyoideus) (not in the canal). (ab) Mental artery (A. mentalis). (b) Inferior alveolar nerve (N. alveolaris inferior) (0. T. inferior dental). (ba) Inferior dental plexus (plexus dentalis inferior). (baa) Inferior dental rami (rami dentales inferiores). (bab) Inferior gingival rami (rami gingivales inferiores). (bb) Mylohyoid nerve (N. mylohyoideus) (not in the canal). (be) Mental nerve (N. mentalis). (bca) Rami to chin (rami mentales). (bcb) Rami to lower lip (rami labiales inferiores). SUBMAXILLAEY EEGION. Draw the tongue forcibly forward and stitch the tip of it to the end of the nose. Throw the head backward to the full extent and turn slightly to the opposite side. Mylohyoid Muscle (M. mylohyoideus) and Subjacent Structures. ^ The structures which have been dissected, cut superficial to this muscle, may now be reflected. Clean the muscle. Study its form, position, origin, insertion, action, and innervation. Cut DISSECTION OF THE HEAD AND NECK 265 FIG. 112. Papittaefoliatae Branch to the mucous membrane of the mouth-cavity Margo lateralis linguae ft Arcm Vlossopalatinm i • \ ! Mucous membrane of the isthmus faucium \ N. lingualis Kami linguales., M. ge Ramus anastomoticus cum n. hypoglosso .... Kami linguales ..: M. geniohyoidcus M. mylohyoideu hyogl nyionyoiariix M. hyoal,*™* Cornu majus ossis hyoidei • Membrana hyothyreoidea Cartilago thyreoidea "' M. cricothyreoideus Glandula thyreoidea TonsiUa palatina - M. xti/Iufi/iit ri/nycus -N. glossopharyngeus X. hj-poglossus M. constrictor pharyngis mcdius N. laryngeus superior -..Ramus interuus Lig. hyothyrcoit}' >nn laterals Ramus externus M. thyreopharyngeus M. cricopharyngeus N. laryngeus inferior > Rami oesophagei Kami tmcheale, * ™^-N'. recurrens The distribution of the Nn. lingualis, glossopharyngeus, and hypoglossus, and also of the Nn. laryn- geus superior and recurrens. The head and neck viscera arc isolated. The upper part of the thyreoid gland has been removed. (After Toldt, Anat. Atlas, Wien, 1903, 3 Aufl., p. 880, Fig. 1323.) 266 LABORATORY MANUAL OF HUMAN ANATOMY through the muscle close to the linea obliqua mandibulae and along the median raphe and turn it downward over the hyoid bone. Saw through the corpus mandibulae a little lateral from the median line. Lift the edge of bone and fasten it by a suture to structures above. Avoid injury to the mucous membrane in the floor of the mouth. Beneath the mylohyoid muscle study carefully the following : Muscles. (a) Hyoglossus muscle (M. hyoglossus). (b) Styloglossus muscle (M. stylo glossus). (c) Genioglossus muscle (M. genioglossus}. (d) Geniohyoid muscle (M. geniohyoideus) . FIG. 113. A. maxillaris externa, M. massetericus M. stylohyoideus Gl. parotis Gl. submaxillaris .M. hyoglossus .M. mylohyoideus M. digastricus A. lingualis M. omohyoid. V. facialis posterior M. thyreohyoideus N. hypoglossusi ^A. thyreoidea superior A. carotis externa: !N. laryngeus superior The structures in the submaxillary region. (After Haeckel in Atlas des Topograph. Anat. des Mensch.— v. Bardeleben, Haeckel, and Frohse-Jena, 1901, Fig. 49.) Nerves. (Fig. 112.) (a) Lingual nerve (AT. lingualis). (aa) Sublingual nerve (N. sublingualis). (ab) Lingual rami (rami linguales). (b) Hypoglossal nerve (N. hypoglossus). (ba) Lingual rami (rami linguales) . What muscles are innervated by the N. hypoglossus? (c) Submaxillary ganglion (ganglion submaxillare) . DISSECTION OF THE HEAD AND NECK 267 To find this dissect in the interval between the N. lin- gualis and the deep part of the glandiila submaxillaris. Find— (ca) Branches communicating with the lingual nerve (rami com- municantes cum N. linguali). (cb) Submaxillary rami (rami submaxillares) . (d) Glossopharyngeal nerve (N. glossopharyngeus) . How does it behave as regards the M. hyoglossus ? Arteries. (a) Lingual artery (A. lingualis}. (Fig. 113.) Veins. (a) Lingual vein (V. lingualis}. (aa) Sublingual vein (V. sublingualis}. (ab) Companion veins to hypoglossal nerve (Vv. comites N. hypoglossi). Salivary Glands. (a) Deep part of submaxillary gland (glandula submaxillaris). (aa) Submaxillary duct (ductus submaxillaris [Whartoni]). (b) Sublingual gland (glandula sublingualis). (ba) Larger sublingual duct (ductus sublingualis major) (0. T. duct of Bartholin). (bb) Smaller sublingual ducts (ductus sublinguales minores) (0. T. ducts of Rivini). Hyoglossal Muscle (M. hyoglossus). Study its form, position, origin, insertion, action, and inner- vation. Then detach it from the hyoid bone and reflect it upward. Study the structures beneath. Arteries. (a) Lingual (A. lingualis) in its second and third parts. (aa) Dorsal rami of tongue (rami dorsales linguae}. (ab) Sublingual artery (A. sublingualis). (ac) Deep artery of tongue (A. profunda linguae) (0. T. ranine artery). Veins. (a) Tributaries of lingual vein. (aa) Companion veins of lingual artery (Vv. comites A. lin- gualis). DEEP DISSECTION OF NECK. Stylopharyngeus Muscle (M. stylopharyngeus). (Vide Spalteholz, Fig. 53I-) Remove the calvarium; sponge the floor of the skull-cavity with alcohol. Cut through the venter posterior M. digastrici near its origin from the incisura mastoidea of the temporal bone, and turn it forward and downward. At this point observe the 268 LABORATORY MANUAL OF HUMAN ANATOMY anastomotic ramus connecting the facial with the glossopharyn- geal nerve (ramus anastomoticus cum N. glossopharyngeo}. From which branch of the N. facialis does it come? Cut through the A. carotis externa at a point just inferior to the terminal bifurcation into the A. temporalis superficial and the A. maxil- ]aris interna; cut through also the A. auricularis posterior and the A. occipital is at their origins and turn the A. carotis externa forward out of the way. Clean the M. stylopharyngeus, avoid- ing injury to the N. glossopharyngeus. Study the form, position, origin, action, and innervation of the muscle. The insertion can be seen best at a later stage of the dissection. Internal Carotid Artery (A. carotis interna). With bone-forceps cut through the base of the processus sty- loideus and reflect it, with the muscles attached to it, downward and forward. The vessels and nerves more medially situated may now be carefully dissected out of the tough fascia in which they lie and traced up to the base of the skull. Secure the pharyngeal rami of the N. vagus early; they will be found on the lateral surface of the A. carotis interna. Study with especial care the interval between the V. jugularis interna and the A. carotis interna just beneath the base of the skull. What is the level of origin of the A. carotis interna? How does it pass into the cranial cavity? Study carefully the compli- cated relations of its cervical portion. Why is its proximity to the pharynx and palatine tonsil emphasized in the text-books ? Smaller Arteries deep in the Neck. (Vide Spalteholz, Figs. 441 and 442.) (a) Ascending pharyngeal artery (A. pharyngea ascendens). Note its relations to the A. carotis interna and to the pharynx. Study the following branches: (aa) Pharyngeal rami (rami pharyngei}. (ab) Posterior meningeal (A. meningea posterior}. (ac) Inferior tympanic (A. tympanica inferior}. (b) Ascending palatine branch of external maxillary (A. palatina as- cendens} (0. T. inferior palatine). (c) Tonsillar ramus of external maxillary (ramus tonsillaris) (0. T. ton- sillitic artery). Internal Jugular Vein (V. jugularis interna) and its Tributaries. With what cerebral sinus is the internal jugular vein con- tinuous? What are the relations of the vein in the jugular fora- men? Where is the superior bulb of the jugular vein (bulbus DISSECTION OF THE HEAD AND NKCK 269 venae jugularis superior) situated? What is the relation of this vein to the other structures contained within the " vascular sheath" of the deep cervical fascia! Observe the entrance of the inferior petrosal sinus (sinus petrosus inferior) into the superior bulb of the vein. Pass a probe through the sinus from the skull cavity into the bulb. Find the pharyngeal plexus (plexus pharyngeus) and tributary veins (Vv. pharyngeae). The following tributaries of the internal jugular have been studied already, but they may now be reviewed with advantage : (a) Lingual vein (V. lingualis). (b) Superior thyreoid veins (Vv. thyreoideae superior -es). (c) Common facial vein (V. facialis communis). Slit open the internal jugular vein and observe the valve. In what part of the vein is it situated? How many flaps are to be seen! Hypoglossal Nerve (N. hypoglossus). (Vide Figs. 92 and 112.) Divide the V. jugularis interna five centimetres below the base of the skull and turn the upper part upward so as to expose the N. hypoglossus better as it emerges from the canalis hypo- glossi (0. T. anterior condyloid foramen). Note the close con- nection of the nerve with the ganglion nodosum of the N. vagus. At what point does the N. hypoglossus enter the anterior triangle of the neck! Note its relation to the A. occipitalis. Demon- strate, if possible, the branches of communication (1) with the superior cervical ganglion of the sympathetic, (2) with the gan- glion nodosum of the N. vagus, and (3) especially with the Nn. cervicales I. and II. What is the significance of the fibres to the N. hypoglossus from the cervical nerves! Make a list of (1) the muscles supplied by the N. hypoglossus proper and (2) the mus- cles supplied by fibres of cervical nerves running in the N. hypoglossus. Eeview the branches of the N. hypoglossus already studied, — viz., (1) ramus descendens, (2) ansa hypoglossi, (3) ramus thyreohyoideus, and (4) rami linguales. Accessory Nerve (N. accessorius) (O. T. Spinal Accessory). (Vide Fig. 92.) What is its relation to the N. vagus and N. glossopharyngeus in the jugular foramen! Study— (a) Internal ramus (ramus internus] (0. T. accessory portion). Follow it to where it fuses with the N. vagus. 270 LABORATORY MANUAL OF HUMAN ANATOMY (b) External ramus (ramus externus) (0. T. spinal portion). Follow it to the sternocleidomastoid muscle. Its peripheral distribution has been studied in the neck. Vagus Nerve (N. vagus) (O. T. Pneumogastric Nerve). (Vide Fig. 92.) Study the two ganglia from the cells of which its constituent sensory fibres arise : (a) Upper or jugular ganglion (ganglion jugulare) (0. T. ganglion of the root). (b) Lower or knotty ganglion (ganglion nodosum) (0. T. ganglion of the trunk). In special dissections from the museum, with the aid of models and atlases, study the following : (a) Meningeal ramus (ramus meningeus) (0. T. recurrent branch). (b) Auricular ramus (ramus auricularis) (0. T. Arnold's nerve). (c) Anastomotic ramus with glossopharyngeal nerve (ramus anastomoti- cus cum N. glossopharyngeo). The following branches, already examined in the dissection of the side of the neck, may be conveniently reviewed : (a) Pharyngeal rami (rami pharyngei). (b) Superior laryngeal nerve (N. laryngeus superior}. (ba) External ramus (ramus externus). (bb) Internal ramus (ramus internus). (be) Ramus anastomosing with. inferior laryngeal nerve (ramus anastomoticus cum N. laryngeo inferiori). (c) Superior cardiac rami (rami cardiaci superior es}. (d) Depressor nerve (N. depressor). (e) Recurrent nerve (N. recurrens) (0. T. recurrent laryngeal). The other branches are studied when the thorax and abdomen are dissected. Glossopharyngeal Nerve (N. glossopharyngeus). (Vide Fig. 112.) Examine its relations in the jugular foramen. Find the two ganglia which give origin to those of its fibres that are sensory : (a) Upper ganglion (ganglion superius) (0. T. jugular ganglion). (b) Lower or petrous ganglion (ganglion petrosum) (0. T. ganglion of Andersch). Find as many of the branches of the N. glossopharyngeus in your own dissection as you can and supplement the study of the DISSECTION OF THE HEAD AND NECK 271 cadaver by that of museum preparations, models, and atlases ; include the following : (a) Tympanic nerve (N. tympanicus) (0. T. Jacobson's nerve). (Vide Spalteholz, Fig. 773.) (aa) Tympanic plexus (plexus tympanicus [ Jacobsoni] ) . (aaa) Superior caroticotympanic nerve (N. caroticotym- panicus superior). (aab) Inferior caroticotympanic nerve (N. caroticotym- panicus inferior). (aac) Tubal ramus (ramus tubae). (b) Ramus anastomosing with the auricular branch of the vagus (ramus anastomoticus cum ramo auriculari N. vagi). (c) Pharyngeal rami (rami pharyngei). (d) Stylopharyngeal branch (ramus stylopharyngeus) . (e) Tonsillar rami (rami tonsillares) (0. T. tonsillitic branches). (/) Lingual rami (rami linguales) (0. T. terminal branches). Cervical Part of Sympathetic System (Pars cervicalis S. sympathici). Note that the sympathetic trunk (truncus sympathicus) in the neck has only three ganglia upon it. (Fig. 92.) (a) Superior cervical ganglion (ganglion cervicale superius). What evidence is there that it represents four segmental sympa- thetic ganglia? (b) Middle cervical ganglion (ganglion cervicale medium). Why does it probably correspond to two primitive ganglia? (c) Inferior cervical ganglion (ganglion cervicale inferius). Note that it represents at least two segmental ganglia. Study the exact level and relations of each of these ganglia. Find the rami communicantes connecting them with the Nn. cervicales. How much have you made out in your dissection of the fol- lowing : (a) Jugular nerve (N. jugularis). (b) Internal carotid nerve (N. caroticus internus). (c) Internal carotid plexus (plexus caroticus internus). (d) External carotid nerves (Nn. carotid externi). (e) External carotid plexus (plexus caroticus externus). (f) Superior thyreoid plexus (plexus thyreoideus superior). (g) Lingual plexus (plexus lingualis). (h) External maxillary plexus (plexus maxillaris externus). (i) Sympathetic root of submaxillary ganglion (radix sympathica gan- glii submaxillaris , . (,;') Occipital plexus (plexus occipitalis) . (k) Posterior auricular plexus (plexus auricularis posterior). (1) Superficial temporal plexus (plexus temporal™ superficialis) . (m) Internal maxillary plexus (plexus maxillaris internus). 272 LABORATORY MANUAL OF HUMAN ANATOMY (n) Common carotid plexus (plexus caroticus communis). (o) Laryngopharyngeal rarni (rami laryngopharyngei). (p) Ascending pharyngeal plexus (plexus pharyngeus ascendens). (q) Superior cardiac nerve (N. cardiacus superior). (r) Middle cardiac nerve (N. cardiacus medius). (s) Subclavian loop (ansa subclavia [ Vieussenii] ) . (*) Inferior cardiac nerve (N. cardiacus inferior). (u) Subclavian plexus (plexus subclavius). (v) Internal mammary plexus (plexus mammarius internus). (w) Inferior thyreoid plexus (plexus thyreoideus inferior}. (x) Vertebral plexus (plexus vertebralis) . Note that all the above, except (a), (i), (o), (g), (r), (s), (t), are plexuses about the larger arteries. Lateral Straight Muscle of the Head (M. rectus capitis lateralis). (Vide Spalteholz, Fig. 304.) Clean the muscle; find its origin and its insertion. What is its action! What nerve supplies it? Find the ramus anterior of the first cervical nerve. How is it related to the M. rectus capitis lateralis? How is the first loop of the plexus cervicalis formed? Divide the attachment of the M. rectus capitis lateralis close to the transverse process of the atlas and turn the muscle upward. Sever the origin of the M. obliquus capitis superior. Find the nerve to the M. rectus capitis lateralis and follow it to its origin from the first cervical nerve (N. suboccipitalis) . STRUCTURES IN FOSSA CEANII MEDIA. Removal of Dura Mater. (a) Cut through the dura mater just lateral from the openings through which the III., IV., and V. nerves pass, from the processus cli- noideus anterior to the apex pyramidis (0. T. tip of petrous bone). (b) Cut through the dura mater from the apex pyramidis backward and lateralward along the line of the sinus petrosus superior as far as the sulcus sigmoideus. (c) Cut through the dura from the processus clinoideus anterior lateral- ward and forward along the posterior margin of the ala parva of the sphenoid bone to its lateral extremity. Lift the dura carefully, keeping the edge of the knife close to the membrane, and thus avoid injury to the nerves attached to it beneath. DISSECTION OF THE HEAD AND NECK 273 Cavernous Sinus (Sinus cavernosus). (Vide Fig. 114.) Where is it situated! What are its boundaries! What im- portant structures pass through it? Note the following tribu- taries : (a) Superior ophthalmic vein ( V. ophthalmica superior) . (b) Inferior ophthalmic vein ( V. ophthalmica inferior). (c) Sphenoparietal sinus (sinus sphenoparietalis). Arteries of the Region. (a) Internal carotid artery (A. carotis interna). How does it enter the cranial cavity? Study its course. (aa) Ophthalmic artery (A. ophthalmica). (Vide Fig. 117.) FIG. 114. N. oculomotorius ,.X. trochlearis Hypophysis-'llllllllJllp^g^; ^ carotis interna X. ophthalmicus N. abducens maxillaris Sinus sphenoidalis-- -* Sinus cavernosus Histological section passing in a frontal plane through the hypophysis, adult (after Langer). (From Poirier et Charpy, Traite d'Anat. hum., Paris, 1901, 2 ed., t. ii. p. 767, Fig. 497. ) (b) Middle meningeal artery (A. meningea media). Through what open- ing does it enter the middle cranial fossa ? In what portion of your dissection did you meet with the origin of this artery? Find the following branches: (ba) Superficial petrosal ramus (ramus petrosus superficial) . (bb) Superior tympanic artery (A. tympanica superior). (c) Accessory meningeal ramus (ramus meningeus accessorius) of A. meningea media. Look for it entering the skull through the fora- men ovale. Nerves of the Region. (a) Trigeminal nerve (N. trigeminus) (0. T. N. cerebralis V.). Observe the exact position of the larger portion (portio major) (sensory) and of the smaller portion (portio minor) (motor) and their relations to the semilunar gan- glion (ganglion semilunare [Gasseri]) (0. T. Gasserian ganglion), the cells of which give origin to the sensory fibres of the nerve (vide Fig. 115). Read carefully a de- scription of the semilunar ganglion in your systematic toxt- 18 274 LABORATORY MANUAL OF HUMAN ANATOMY book and compare this with the findings in the cadaver. Study the mode of formation of the cavum Meckelii. Ex- amine the three great trunks: (aa) Ophthalmic nerve (N. ophthalmicus). (ab) Maxillary nerve (N. maxillaris) (0. T. superior maxillary). FIG. 115. N. lacrimalis N. nasociliaris Ganglion ciliare N. supratrochlearis N. ethmoidalis N. infratrochlearis N. supraorbitalis Ganglion sphenopalatinum N. canalis pterygoidei (Vidii) Plexus caroticus internus Ganglion oticum i Ganglion semilunare (Gasseri) N. zygomaticus Kami nasales anteriores K Kami nasales posteriores -/-— 3 N. infra-. orbitalis N. petrpsus super- ficialis major ; N. petrpsus super- ticialis minor Chorda tympani Kami alveolares superiores Nn. palatini'' Ganglion cervicale superius N. alveolaris inferior Nn. carotici extern! . Ganglion submaxillare -^Plexus caroticus externus ^ Plexus maxillaris externus A. carotis communis » Plexus alveolaris inferior N. mentalis Schematic representation of the N. trigeminus and its connections. (After Toldt, Anat. Atlas, Wien, 1903, 3 Aufl., p. 859, Fig. 1298.) (ac) Mandibular nerve (N. mandibularis) (0. T. inferior maxil- lary). Do these trunks arise from the convexity or from the concavity of the ganglion? With which is the motor root (portio minor) combined? Find the following branches of the N. ophthalmicus : DISSECTION OF THE HEAD AND NECK 275 (aca) Frontal nerve (N. frontalis). (acb) Lacrimal nerve (N. lacrimalis) . (ace) Nasociliary nerve (N. nasociliaris) . Through what openings does the N. maxillaris leave the skull? Find the meningeal branch (N. meningeus (medius)). Through what openings does the N. mandibularis leave the skull? Observe its relation to the ramus meningeus accessorius of the A. meningea media. (b) Oculomotor nerve (N. oculomotorius) (0. T. N. cerebralis III.). (ba) Superior branch (ramus superior). (bb) Inferior branch (ramus inferior). (c) Trochlear nerve (N. trochlearis) (0. T. nervus patheticus; N. cere- bralis IV.). (d) Abducent nerve (N. abducens) (0. T. N. cerebralis VI.). (e) Cavernous plexus of sympathetic (plexus cavernosus). (f) Larger superficial petrosal nerve (N. petrosus superficialis major). (g) Smaller superficial petrosal nerve (N. petrosus superficialis minor). ORBIT. Removal of Roof of Orbit (Facies superior orbitae). Chisel away the thick bone forming the cranial wall above the aditus orbitae, but leave unbroken the supraorbital margin (mar go supraorbitalis). Remove carefully the whole of the thin roof of the orbit (paries superior). With bone-forceps cut away that part of the ala parva of the sphenoid bone which forms the superior orbital fissure (fissura orbitalis superior) (0. T. sphe- noidal fissure). Cut away the processus clinoideus anterior. The periosteum of the paries superior is now exposed ; note its continuity with the dura mater through the superior orbital fissure. Cut through it sagittally midway between the lateral and medial walls of the orbit and also transversely near the anterior margin of the paries superior. Reflect the two halves medialward and lateral ward respectively. Grasp the front of the bulbus oculi with forceps, pull it forward, and fasten to the nose by means of needle and thread passed through the tunica conjunctiva bulbi. Avoid perforation of the eyeball proper. Frontal Nerve (N. frontalis). Find it lying upon the upper surface of the M. levator pal- pebrae superioris. Clean it and the upper surface of the muscle, avoiding, in front, the A. supraorbitalis. Study the following branches of the N. frontalis : 276 LABORATORY MANUAL OF HUMAN ANATOMY (a) Supraorbital nerve (N. supraorbitalis) . (b) Frontal ramus (ramus frontalis). (c) Supratrochlear nerve (N. supratrochlearis) . The peripheral distribution of these nerves has already been studied in the dissection of the face. Trochlear Nerve (N. trochlearis) (O. T. Patheticus, or Fourth Cran- ial Nerve). Carefully remove the fat along the medial wall of the orbit until the M. obliquus is found. On its hinder part find the troch- lear nerve. Notice the abundance of fat in the orbit (corpus adiposum orbitae). Lacrimal Nerve (N. lacrimalis). Look for it on the lateral wall of the orbit along with the A. lacrimalis above the superior margin of the M. rectus lateralis. Besides the branches to the lacrimal gland, secure the anasto- motic ramus to the zygomatic nerve (ramus anastomoticus cum N. zygomatico}. The student will recall having studied the ter- minals of the N. lacrimalis (rami palpebrales) in the dissection of the upper eyelid. Elevator Muscle of Upper Eyelid (M. levator palpebrae superioris). Study this muscle carefully. On lifting it, the minute branch of the N. oculomotorius innervating it may be seen approaching it from the upper surface of the M. rectus superior. Lacrimal Glands. (a) Superior lacrimal gland (glandula lacrimalis superior}. (b) Inferior lacrimal gland (glandula lacrimalis inferior). (c) Accessory lacrimal glands [inconstant] (glandulae lacrimales ac- cessoriae). (d) Excretory ductules (ductuli excretorii [Gl. lacrimalis]). Fascia of Eyeball (Fascia bulbi [Tenoni]) (O. T. Capsule of Tenon). Divide the N. frontalis in the middle of the orbit and reflect the stumps. Cut through the M. levator superioris in the middle and reflect. With the point of a sharp narrow-bladed knife make an oblique valvular opening into the eyeball at the junction of cornea and sclera. Introduce the tip of a blow-pipe and inflate the eyeball with air. On withdrawal, the valve-like character of the opening prevents the escape of the air. Pick up with DISSECTION OF THE HEAD AND NECK 277 forceps the upper part of the loose bursa-like tissue (fascia bulbi [Tenoni]) (O. T. capsule of Tenon) at the back of the eyeball and remove a bit with scissors. Through the opening thus made introduce the handle of the knife, and explore the interfascial space (spatium inter -fas dale [Tenoni]). Determine the extent of the space. What is the relation of the tendons of the eye- muscles to the fascia bulbi? Superior Straight and Superior Oblique Muscles of Eye (M. rectus superior; M. obliquus superior). Establish the form, position, origin, insertion, innervation, and action of each. Examine carefully the pulley (trochlea) through which the tendon of the superior oblique muscle runs. FIG. 116. M. leva tor palpebral superior M. obliquus superior Vasa ophthalmie'u M. rectus lateralis N. ophthalmicus M. rectus inferior Sinus maxillaris Frontal section through the right orbit behind the bulbus oculi. Posterior surface. (From Gegenbaur, Lehrb. der Anat. des Mensch., Leipzig, 1899, 7 Aufl., Bd. ii. p. 589, Fig. 715.) Optic Nerve and Neighborhood. (Vide Fig. 116.) Cut through the M. rectus superior and reflect the ends. Beneath its posterior part find the ramus superior of the N. oculomotorius. Remove the fat over the optic nerve and study the following structures : (a) Optic nerve (N. opticus). (b) Nasociliary nerve (N. nasociliaris) (0. T. nasal nerve). (ba) Long root of ciliary ganglion (radix longa ganglii ciliaris). (bb) Long ciliary nerves (Nn. ciliares longi). (be) Posterior ethmoidal nerve (N. ethmoidalis posterior). (bd) Anterior ethmoidal nerve (N. ethmoidalis anterior). (be) Infratrochlear nerve (N. infratrochlearis). (bea) Superior palpebral branch (ramus palpebralis supe- rior). 278 LABORATORY MANUAL OF HUMAN ANATOMY (beb) Inferior palpebral branch (ramus palpebralis infe- rior) (already studied in dissection of the face). (bf) Anterior nasal rami (rami nasales anteriores) (to be studied further when the nasal cavity is dissected). (c) Ciliary ganglion (ganglion ciliare) (0. T. lenticular or ophthalmic ganglion ) . (ca) Short ciliary nerves (Nn. ciliares breves). Try to find also the sympathetic roots of the ciliary gan- glion (radices sympathicae ganglii ciliaris). Blood-vessels of Orbit. Arteries. (a) Ophthalmic artery (A. ophthalmica). (aa) Central artery of retina (A. centralis retinae). (ab) Lacrimal artery (A. lacrimalis). (aba) Lateral palpebral arteries (Aa. palpebrales lat- er ales}. (ac) Muscular rami (rami musculares). FIG. 117. N. nasociliaris N. frontalis .— N. ethmoidalis anterior- N. frontalis j X X. lacrimalis -a—\. ophthalmica A. supraorbitalis A. ethmoidalis anterior \. lacrimalis A. ophthalmica Relation of the branches of the ophthalmic artery to the nerves. (After Poirier et Charpy, Trait6 d'Anat. hum., Paris, 1901, 2 ed., t. ii. p. 698, Fig. 103.) (ad) Short posterior ciliary arteries (Aa. ciliares posteriores breves). (ae) Long posterior ciliary arteries (Aa. ciliares posteriores longae). (af) Anterior ciliary arteries (Aa. ciliares anteriores). (a fa) Episcleral arteries (Aa. episclerales) . (afb) Anterior conjunctival arteries (Aa. conjunctivales anteriores). DISSECTION OF THE HEAD AND NECK 279 (ag) Supraorbital artery (A. supraorbitalis) . (ah) Posterior ethnioidal artery (A. ethmoidalis posterior), (ai) Anterior ethmoidal artery (A. ethmoidalis anterior), (aj) Medial palpebral arteries (Aa. palpebrales mediates). Note especially — (aja) Superior tarsal arch (arcus tarseus superior). (ajb) Inferior tarsal arch (arcus tarseus inferior). (ajc) Posterior conjunctival arteries (Aa. conjuncti-t vales posterior es] . (ak) Dorsal artery of nose (A. dorsalis nasi) (0. T. nasal branch). (al) Frontal artery (A. frontalis). Veins. (Tributaries of the sinus cavernosus.) (a) Superior ophthalmic vein (V. ophthalmica superior). (aa) Naso frontal vein (V. naso frontalis) . (ab) Anterior and posterior ethmoidal veins (Vv. ethmoidales anterior et posterior). (ac) Lacrimal vein (V. lacrimalis). (ad) Muscular veins (Vv. muscular es). (b) Inferior ophthalmic vein (V. ophthalmica inferior). (c) Central vein of retina (V. centralis retinae). The following veins of the bulbus oculi and of the eyelids are drained partly by the V. ophthalmica superior, partly by the V. ophthalmica inferior: (d) Vortex veins (Vv. vorticosae). (e) Posterior ciliary veins (Vv. ciliares posteriores) . (f) Anterior ciliary veins (Vv. ciliares anteriores). (g) Episcleral veins (Vv. episclerales) . (h) Palpebral veins (Vv. palpebrales). (i) Anterior and posterior conjunctival veins (Vv. conjunctivales pos- teriores et anteriores). Other Straight Muscles of Eyeball. The M. rectus superior has already been studied and re- flected. Examine the origin, insertion, position, action, and innervation of each of the following muscles : (a) Medial straight muscle (M. rectus medialis) (0. T. rectus internus). (b) Inferior straight muscle (M. rectus inferior). (c) Lateral straight muscle (M. rectus lateralis) (0. T. external rectus). (ca) Lacertus of lateral straight muscle (lacertus musculi recti lateralis). Divide the N. opticus close to the foramen opticum and turn the eyeball forward. Examine the attachment of the eye-muscles behind. What is meant by the common tendinous ring of Zinn (annulus tendineus communis [Zinni]) (O. T. ligament of Zinn)? 280 LABORATORY MANUAL OF HUMAN ANATOMY How are the muscles of the eye (musculi oculi} inserted into the eyeball (bulbus oculi} ? Oculomotor and Abducent Nerves (Nn. oculomotorius et abducens). Study these two nerves through their course. (a) Oculomotor nerve (N. oculomotorius) (0. T. third nerve). (aa) Superior ramus (ramus superior). (ab) Inferior ramus (ramus inferior). (aba) Short root of ciliary ganglion (radix brevis ganglii ciliaris) (0. T. motor root of lenticular ganglion). (b) Abducent nerve (N. abducens) (0. T. sixth nerve). What muscle does it innervate? FIG. 118. M. rect. sup.. .M. lev. palp. sup. A. ophthal. i : M. obliq. sup. N. lacrimalis ^ N. frontalis -J N. trochlearis - -*. N. ophthal. sup. -j| N. abducens M. rect. lat.- N. opticus. - — Annulus tend. com. [Zinni] . rect. med. M. rect. inf/ ; N nasociliaris 'Ram. inf. N. oculomotorii Schema of the annulus tendineus communis [Zinni] and its relations to the nerves of the orbit. (From Poirier et Charpy, Trait6 d'Anat. hum., Paris, 1899, t. iii., 3, p. 794, Fig. 440.) Compare the arrangement of the various nerves in the supe- rior orbital fissure (fissura orbitalis superior) (0. T. sphenoidal fissure) with that of the nerves in the sinus cavernosus. What are the principal differences ? Inferior Oblique Muscle of Eye (M. obliquus inferior). Replace the eyeball in its natural position. Evert lower eye- lid, and dissect off conjunctiva in the region of the fornix con- junctivae inferior. Find the inferior oblique muscle and clean it. Study its origin, insertion, action, and innervation. DISSECTION OF THE HEAD AND NK< K 281 FIG. 119. Ram. sup. N. oculomotorii N. maxillaris : N. abducens N. oculomotorius X. mandibularis i N. ophthalmicus i N. maxillaris G. sphenopalat. : ; Nn. ciliar. brev. N. infraoi i* Branch to M. obi. inf. G. ciliare Distribution of the N. oculomotorius (after Hirschfeld). (From Poirier et Charpy, Traits d'Anat. hum. Paris, 1899, t. iii., 3, p. 796, Fig. 441.) FIG. 120. Upper border of the tarsus superior Cut edge of the fascia muscularis Spatium interfasciale (Tenoni) Fascia bulbi (Tenoni) Tendon of the M. obliquus superior M. reotus medialis- N/opticus M. levator palpebrae superioris (turned forward) ^.Glandula lacrimalis Fascia musrularis of the M. n-ctus snj.rri.ir jit'tcr i«nssiii«- through the fascia hull.i M. reel i is superior M. Tvrtuslateralis The capsule of Tenon (fascia bulbi) and its relation t.. the superior reel us miMcle of the right eye. Seen from above. (After Toldt, Ami. Atlas, Wi(>n, 1903, 3 Aufl., p. 907, Fig. 1379.) 282 LABORATOKY MANUAL OF HUMAN ANATOMY Fascia of Bulb (Fascia bulbi [Tenoni]) (O. T. Capsule of Tenon). Compare the fascia in the eye before you with a description of it in some good systematic text-book. Open the interfascial space (spatium interfasciale [Tenoni]). (Compare Lockwood, J. Anat. and Physiol., Lond., vol. xx., 1885.) What is meant by the " fat body of the orbit" (corpus adiposum orbitae) 1 Zygomatic Nerve (N. zygomaticus) (O. T. Temporomalar Nerve). Find this nerve entering the orbit through the inferior orbital fissure (fissura orbitalis inferior) (0. T. sphenomaxillary fis- sure). Follow its two branches : (a) Zygomaticotemporal ramus (ramus zygomaticotemporalis) (0. T. temporal branch of temporomalar). (b) Zygomaticofacial ramus (ramus zygomaticofacialis} (0. T. malar branch of temporomalar). Recall where the terminals of these two rami were previously met with in the dissection. REGION IN FRONT OF CERVICAL SPINE (PRE VER- TEBRAL REGION). Place the dissection upside down, the cut margin of the cra- nium resting on the table. Cut through the A. carotis communis, V. jugularis interna, N. vagus and truncus sympathicus on each side at level of neck of first rib. Displace trachea, oesophagus, large vessels and nerves forward, separating them from the front of the spine. Complete the separation to the base of the skull, but be careful not to injure adjacent structures. Make a transverse cut through the thick periosteum on the pars basilaris of the occipital bone, the knife passing between the pharynx in front and the prevertebral muscles behind. Rest the inside of the base of the skull (basis cranii interna) upon a wooden block, apply a chisel in the line of the cut through the periosteum of the basis cranii externa (between pharynx and prevertebral mus- cles), and with a wooden mallet cut through the pars basilaris of occipital bone. Turn the head first on one side and then on the other, in each instance making a saw-cut through the side of the cranium from a point one centimetre behind the processus mastoideus, obliquely forward and medialward, to a point just behind the jugular foramen. Next place the dissection in such a position DISSECTION OF THE HEAD AND NECK 283 that the basis cranii interim looks upward; on each side com- plete the division of the base of the skull by chiselling through the solid interval still left, — i.e., from the lateral extremity of the chisel-cut through the pars basilaris backward upon the medial side of the jugular foramen to the medial end of the saw-cut. FIG. 121. Pars basilaris Process^ ^ofdCMf— \--"l*li£ >MHBWiW«\i" /"M" rectus Capitis latt'mlis Processm, ...— m •••••» air !• • • i •-^^•^•v posterior) culum anteriux utlanti* M. longus capitis . levator scapulae !M_ _M. longus colli ossis occipitalis Pars prtrosa ossis tempo rains M. scalenus medius M. scalenus anterior ~.M. scalenus posterior Scalenus-space costae II. The deep muscles of the front of the neck. (After Toldt, Anat. Atlas, Wk-n, 1900, 3 Aufl., p. 294, Fig The forepart of the skull (with the pharynx and great vessels and nerves) is now to be separated from the hind part (with the cervical spine). The N. hypoglossus is cut through close to the base of the skull, but should not be separated from the gan- glion of the N. vagus. Wrap the pharynx and forepart of the 284 LABORATORY MANUAL OF HUMAN ANATOMY skull in moist carbolized cloths and oil-cloth and lay aside for subsequent dissection. In the posterior part of the dissection work out the following : Muscles. (a) Lateral straight muscle of head (M. rectus capitis lateralis). This has been studied before in the deep dissection of the neck. (b) Anterior straight muscle of head (M. rectus capitis anterior) (O. T. rectus capitis anticus minor). (c) Long muscle of head (M. longus capitis) (0. T. rectus capitis an- ticus major). (d) Long muscle of neck (M. longus colli). Determine the form, position, origin, insertion, action, and innerva- tion of each of the above muscles. Review the attachments of the Mm. scaleni. Then cut away entirely the prevertebral and scalene muscles and study from in front — (e) Intertransverse muscles (Mm. intertransversarii) . (ea) Anterior (Mm. intertransversarii anteriores). (eb) Posterior (Mm. intertransversarii posteriores) . Nerves. Eight cervical nerves (Nn. cervicales I.~VIII.). (a) First cervical nerve (N. cervicalis I.). (aa) Anterior ramus (ramus anterior) (0. T. anterior primary division). (ab) Posterior ramus (ramus posterior, or N. suboccipitalis) (0. T. posterior primary division). (b) Second cervical nerve (N. cervicalis II.). (ba) Anterior ramus (ramus anterior) (0. T. anterior primary division ) . (bb) Posterior ramus (ramus posterior) (O. T. posterior pri- mary division). (bba) Medial ramus (ramus medialis, or N. occipitalis major). (bbb) Lateral ramus (ramus lateralis). (c) Third to eighth cervical nerves (Nn. cervicales III -VIII.). (ca) Anterior rami (rami anteriores) (0. T. anterior primary divisions). (cb) Posterior rami (rami posteriores) (0. T. posterior pri- mary divisions). Blood-vessels. Remove the intertransverse muscles (Mm. intertransversarii), M. rectus capitis lateralis, M. obliquus capitis superior, and M. obliquus capitis inferior. With bone-forceps cut away the anterior tubercles and costal processes of the transverse processes of the third, fourth, fifth, and sixth cervical vertebrae. Study— (a) Vertebral artery (A. vertebralis) . (aa) Spinal rami (rami spinales). Find the plexus vertebralis of the sympathetic around the artery. (b) Vertebral vein (V. vertebralis). DISSECTION OF THE HEAD AND NECK Ramus muscularis for the Mm. recti capitis, anterior and lateralis and the M. longus capitis M. rectus capitis lateral iv Ramus muscularis for the Mm. longus capitis. and longus colli \ Anastomosing branch to the ramus descendens. X. hypoglossi X. occipitalis minor. Anastomosing branch to the ramus externus X. accessorii X. auricularis magnus — « XT. cutaneus colli. Nn. supraclaviculares-x;^". N. phrenicus— '— - N. dorsalis scapulae— N. suprascapularis.— — - FIG. 122. A. i-arotix hit< run X. axillari X. radialis X. musculo-- cutaneus X. mediam X. ulnaris X. cutaneus anti-.' brachii medialis Xn. snbscapulares''''' ^ X. thoracalis loogttB M. rectus capitis anterior X. caroticus internus /X. cervicalis I. Ramus communicans X. cervicalis II. Ganglion cervicale superius Xn. cen-icales III., IV. Ramus communicans A. vertebral! s $• ^^Truncus sympathicus Xn. cervicalesV., VI., VII. ^Ganglion cervicale medium ,X. cervicalis VIII. Gangfipn cervicale inferius V , • - Ganglion thoracale I. E X. thoracalis I. ••-. ^Plexus vertebralis • Plexus subclavius \AlM sulx'lavia • (Vieuss«-iiii i M. serratus anterior Xn. thoracal.^ M. scalcnus mcdius anteriores The cervical and brachial plexuses. (After Toldt, Anat. Atlas, Wien, li»OS. :i Aufl., p. sic,. Kitf. 1'Jiv) 286 LABORATORY MANUAL OF HUMAN ANATOMY LIGAMENTS OF VERTEBRAL COLUMN AND SKULL (LIGAMENTA COLUMNAE VERTEBRALIS ET CRANII). Remove all muscles from the spinal column and posterior part of the bones of the skull and study the following : (a) Joints of the lower five cervical vertebrae. (aa) Intervertebral fibrocartilages (fibrocartilagines interverte- b rales), (aaa) Fibrous ring (annulus ftbrosus). FIG. 123. Pars basilaris os. occip. Lig. apicisdentis | Mem. atlanto-occipitalis ant. Bursa Caps, artic. of the articulatio ••— atlanto-epistrophica Lig. atlanto-epistrophicum ant. .... . Lig. longitudinale anterius .*••- Lig. longitudinale posterius __. Supra-odontoid synovial cavity — Memb. tectoria .... Lig. cruc. atlantis (superior limb) Lig. trans, atlantis . Synovial cavity of the lig. trans, atlan. Bursa Lig. cruc. atlan. (inferior limb) Epistropheus VAVy^ Sagittal section through the articulationes atlanto-occipitalis and atlanto-epistrophica. .From Pomer et Charpy, Traite" d'Anat. hum., Paris, 1899, 2 ed., t. i. p. 814, Fig. 799.) (aab) Pulp-like nucleus (nucleus pulposus). What is the relation of this to the chorda dorsalis of the embryo ? (ab) Yellow ligaments (ligamenta ftava) (0. T. ligamenta sub- flava). DISSECTION OF THE HEAD AND NECK 287 (ac) Joint-capsules (capsulae articulares) . (ad) Intertransverse ligaments (ligamenta intertransversaria) . (ae) Interspinous ligaments (ligamenta interspinalia) . (af) Supraspinous ligament (ligamentum supraspinale) . Here called the ligamentum nuchae. (ag) Anterior longitudinal ligament (Lig. longitudinale anterius) (0. T. anterior common ligament). (ah) Posterior longitudinal ligament (Lig. longitudinale posterius) (0. T. posterior common ligament). (b) Joint between atlas and occipital bone (articulatio atlanto-o'ccipitalis) . What kind of joint is it? Study— (ba) Joint-capsules (capsulae articulares). (bb) Anterior atlanto-occipital membrane (membrana atlanto- occipitalis anterior). (be) Posterior atlanto-occipital membrane (membrana atlanto- occipitalis posterior). (c) Joint between atlas and epistropheus or axis (articulatio atlanto- epistrophica) . (ca) Joint-capsules (capsulae articulares). FIG. 124. Pars basilaris ossis occipitalis | . cruciatum atlantis Lig. alare. f Lig. transversum atlantis Lig. cruciatum atlantis Lig. cruciatum atlantis— posterior view. (From Poirier et Charpy, Traittf d'Anat. hum., Paris, 1899, 2 ed., t. i. p. 818, Fig. 802.) Before studying further, cut away the posterior arches of the atlas and epistropheus with heavy bone-forceps. With a saw, cut through the occipital bone on each side from a point behind the processus jugularis and the condylus occipitalis into the foramen magnum, so that the whole squama occipitalis may be removed. Remove the dura mater and study the following: (cb) Tectorial membrane ("roof-membrane") (membrana tecto- ria) (0. T. posterior occipito-axial ligament). 288 LABORATORY MANUAL OF HUMAN ANATOMY Detach this from the epistropheus and reflect it upward. Study the following : (cc) Cruciform ligament of atlas (ligamentum cruciatum atlantis). Observe its two parts (cf. Spalteholz, vol. i., Fig. 218) : (cca) Transverse ligament (ligamentum transversum at- lantis). (ccb) Vertical part. Detach the vertical part, reflect it downward, and study — (cd) Alar ligaments (ligamenta alaria) (0. T. odontoid or check ligaments). (ce) Ligament of apex of tooth (ligamentum apicis dentis) (0. T. suspensory ligament). How is this ligament related to the chorda dorsalis? Name from before backward the ligaments of the articulatio atlanto-occipitalis and articulatio atlanto-epistrophica. (Cf. Spalteholz, p. 169.) What movements can occur at these joints! What muscles are concerned in such movements ? How is excessive movement in any direction checked ? MOUTH AND FAUCES. Eeturning to the forepart of the skull and neck, the dissector now studies the following, comparing his findings in the cadaver with illustrations in atlases and descriptions in his systematic text-book. Cavity of Mouth (Cavum or is). General. (a) Cheek (bucca). (aa) Fat body of cheek (corpus adiposum buccae). (b) Entrance to mouth (vestibulum oris). This is bounded in front and laterally by lips and cheeks, behind by teeth and gums. (c) Mouth cavity proper (cavum qris proprium). This is internal to the teeth. (d) Mouth slit or oral fissure (rima oris). (e) Lips of mouth (labia oris). (ea) Upper lip (labium superius). (eb) Lower lip (labium inferius). (f) Junction of lips (commissura labiorum). (g) Angles of mouth (angulus oris). (h) Palate (palatum). (ha) Hard palate (palatum durum). (hb) Soft palate (palatum molle). (he) Middle ridge of palate (raphe palati). DISSECTION OF THE HEAD AND NECK 289 FIG. 125. Septum cartilagineum Septum mobile nasi Cavum nasi Palatum durum Tonsilla pharyngea , Ostium pharyngeum tubae ^.Fornix pharyngis ^^ ,,.Pars nasalis pharyngis Isthmus faucium Velum ---- palatinum Epistropheus Pare oralis pharyngis Lymphoglandula- M. mylohyoideus' _Pars laryngea pharyngis Vestibulum laryngis .... Prominentia laryngea — Cavum laryngis Trachea - Isthmus glandulae thyreoideae— Venae thyreoideae inferiores -^ Vena anonyma sinistra — Thymus. J Cavum pericardii-^ Auricula cordis dextra Corpus tfrrui j Pericardium Sulcus coronarius cordis Atrium cordis dextrum Arteria anonyma -Aorta ascendent If Oesophagus (pars thoracalis) ordisdextrum \ \ *Lymphoglandulae bronchioles Cavum pcricardii ; perlcar(num Atrium cordis sinistrum The viscera of the head and neck and their connections in the thorax. (After Toldt, Anat. Atlas, Wien, 1900, 2 Aufl., p. 395, Fig. 636. ) 19 29Q LABORATORY MANUAL OF HUMAN ANATOMY Mucous Membrane of Mouth (Tunica mucosa oris). (a) Check-cord of upper lip (frenulum labii superioris). (b) Check-cord of lower lip (frenulum labii inferioris). (c) Gum (gingiva). (d) Sublingual caruncle (caruncula sublingualis). (e) Sublingual fold (plica sublingualis} . (/) Transverse palatine folds (plicae palatinae transversae). (g) Incisor papilla (papilla incisiva). Glands of Mouth (Glandulae oris). (a) Labial glands (glandulae labiales). (b) Buccal glands (glandulae buccales). (c) Molar glands (glandulae molares). (d) Palatine glands (glandulae palatinae). (e) Lingual glands (glandulae linguales). (f) Anterior lingual gland (glandula lingualis anterior [Blandini, Nuhni]) (0. T. gland of Nuhn). (g) Sublingual gland (glandula sublingualis). (ga) Larger sublingual duct (ductus sublingualis major). (gb) Smaller sublingual ducts (ductus sublinguales minores). (h) Submaxillary gland (glandula submaxillaris) . (ha) Submaxillary duct (ductus submaxillaris [Whartoni]) (0. T. Wharton's duct). (i) Parotid gland (glandula parotis). (ia) Retromandibular process (processus retromandibularis) (0. T. socia parotidis). (ib) Accessory parotid gland (glandula parotis accessoria). (ic) Parotid duct (ductus parotideus [Stenonis]) (0. T. Steno's duct). (j) Mixed mouth secretions (saliva). Teeth (Denies). (a) Superior dental arch (arcus dentalis superior). (b) Inferior dental arch (arcus dentalis inferior). How many teeth does each arch contain ? (c) Incisor teeth (denies incisivi). (d) Canine teeth (dentes canini). (e) Premolar teeth (dentes praemolares) (0. T. bicuspids). (/) Molar teeth (dentes molares). (fa) Late tooth (dens serotinus) (0. T. wisdom tooth). How many of these teeth are present in your cadaver? What is meant by deciduous teeth (dentes decidui) and permanent teeth (dentes permanent es) ? Tongue. (Vide Figs. 125 and 137.) (a) Dorsum of tongue (dorsum linguae). What is a " coated tongue" ? (b) Root of tongue (radix linguae). (c) Inferior surface (fades inferior [linguae]). (d) Lateral margin (margo lateralis [linguae]). (e) Apex or tip of tongue (apex linguae). (f) Mucous membrane (tunica mucosa linguae). The muscles of the tongue and the details of the mucous mem- brane will be studied later. DISSECTION OF THE HEAD AND NECK 291 Fauces. (a) Isthmus of fauces (isthmus faucium). (b) Palatine curtain (velum palatinum). (c) Uvula (uvula palatinum). This little body is often cut off by the surgeon if it becomes so relaxed and lengthened that it causes continued tickling of the throat. (d) Palatine arches (arcus palatini). (da) Glossopalatine arch (arcus glossopalatinus) (0. T. ante- rior pillar of fauces). (db) Pharyngopalatine arch (arcus pharyngopalatinus) (0. T. posterior pillar of fauces). (e) Tubopalatine or salpingopalatine fold (plica salpingopalatina) . This cannot be seen well until later, when the pharynx is opened from behind. (/) Palatine tonsil (tonsilla palatina) (0. T. ordinary tonsil). This will be studied later. The muscles of the palate and fauces will be studied with those of the pharynx. PHARYNX. Place the chin of the cadaver on a block with the pharynx hanging downward, its posterior surface turned towards dis- sector. Distend the cavity of the pharynx with cotton or tow. Buccopharyngeal Fascia (Fascia buccopharyngea). (a) Pterygomandibular raphe (raphe pterygomandibularis) (0. T. ptery- gomaxillary ligament). This will be seen as a dense cord between the hamulus pterygoideus and the posterior end of the crista buc- cinatoria [mandibulae] ) . Observe that the part of the fascia in front of (a) covers the M. buccinatorius, that behind (a) covers the muscles of the pharynx. Muscular Tunic of Pharynx (Tunica muscularis pharyngis). Study the form, position, origin, insertion, action, and inner- vation of each of the following muscles : (a) Inferior constrictor muscle of pharynx (M. constrictor pharyngis inferior). (aa) Thyreopharyngeal muscle (M. thyreopharyngeus). (ab) Cricopharyngeal muscle (M. cricopharyngeus) . (b) Middle constrictor muscle of pharynx (M. constrictor pharyngis medius). (ba) Chondropharyngeal muscle (M. chondropharyngeus) (from cornu minus os. hyoid.). (bb) Ceratopharyngeal muscle (M. ceratopharyngeus) (from cornu majus os. hyoid.). 292 LABORATORY MANUAL OF HUMAN ANATOMY Between (a) and (b) observe the A. laryngea inferior and the ramus internus of the N. laryngeus superior perforating the membrana hyo- thyreoidea. FIG. 126. Processus pterygoideus (lamina medialis} M. tensor veil mlatini Raphe pterygo- mandibularis M. buccinator M. hyoglossus Tendo M. digastrici Lamina membranacea tubae auditivae _M. levator veli palatini ~; Fascia pharyngobasilaris M. pterygo- pharyngeus - M. bucco- pharyngeus M. mylo- pharyngeus M. con- strictor pharyngis superior M. myloh Os hyoideum Membrana hyothyreoidea/ — M. glosso- pharyngeus j - M. stylopharyngeus M. styloglossus M. chondro-1 pharyngeus M. constrictor V pharyngis -M. cerato- medius pharyngeus j -Accessory muscle-bundle springing from the tendon of the M. stylohyoideus — Cartilago thyreoidea Tendinous streak J M. circothyreoideus. .M. thyreo- ] pharyngeus M. crico- pharyngeus M. constrictor pharyngis inferior Cartilago cricoidea Oesophagus "^•""'•n'- 'TUfth*' The muscles of the pharynx The ramus of the mandible and the styloid process of the temporal bone )een removed. (After Toldt, Anat. Atlas, Wien, 1900, 2 Aufl., p. 417, Fig. 682.) Next cut through the M. pterygoideus internus at its middle and s two ends; avoid injury to M. tensor veli palatini just medial (c) Superior constrictor muscle of pharynx (M. constrictor pharyngis superior}. DISSECTION OF THE HEAD AND NECK 293 (ca) Pterygopharyngeal muscle (M. pterygopharyngeus). (cb) Buccopharyngeal muscle (M. buccopharyngeus). (cc) Mylopharyngeal muscle (M. mylopharyngeus) . (cd) Glossopharyngeal muscle (M. glossopharyngeus). Between (b) and (c) observe the M. stylopharyngeus and the N. glossopharyngeus. Observe the interval between the uppermost con- strictor muscle and the base of the skull; here a thickened portion of the tela submucosa pharyngis (0. T. pharyngeal aponeurosis), called the pharyngobasilar fascia (fascia pharyngobasilaris) , is visible. The semilunar space where the muscle is absent is sometimes called the " sinus of Morgagni." In the lateral part of this on each side the M. levator veli palatini, the M. tensor veli palatini, and the cartilage of the Eustachian tube (cartilago tubae auditivae) can be seen; these structures will be dissected out carefully later. Cavity of Pharynx (Cavum pharyngis). Open the pharynx from behind by a vertical incision in the median line of its posterior wall along its whole length. Divide the fascia pharyngobasilaris close to the basis cranii externa on each side, carrying the knife from the median line lateralward as far as the cartilage of the Eustachian tube. Remove the stuff- ing of tow or cotton. Sponge the tunica mucosa clean and study the cavum pharyngis. With what cavities or tubes does the cavity of the pharynx communicate? Explore the " vault of the pharynx " (fornix pharyngis). How is the cavity of the pharynx bounded ? What very important structures are related to its lateral walls? Where does the pharynx end and the oesophagus begin? Observe the three parts of the cavum pharyngis (see Fig. 125) : (a) Nasal part (pars nasalis) (0. T. nasopharynx). (b) Oral part (pars oralis) (0. T. oral pharynx). (c) Laryngeal part (pars laryngea) (0. T. laryngopharynx). Find— - (d) Pharyngeal opening of Eustachian tube (ostium pharyngeum tubae auditivae}. (da) Anterior lip (labium anterius). (db) Posterior lip (labium posterius). This is sometimes called the tubal projection (torus tubarius), owing to the rounded eminence it forms. (dc) Salpingopharyngeal fold (plica salpingopharyngea) . It extends downward from the lower end of the labium posterins. (e) Pharyngeal recess of Rosenmiiller (recessus pharyngeus [Rosen- mulleri]) (0. T. recessus infundibuliformis). (/) Pharyngeal tonsil (tonsilla pharyngea) (0. T. Luschka's tonsil). It is enlargement of this tonsil that constitutes the " post- adenoids" so often met with in children. (fa) Tonsillar crypts (fossulae tonsillares). 294 LABORATORY MANUAL OF HUMAN ANATOMY (g) Pharyngeal bursa (bursa pharyngea}. Look into the nasal cavity behind and observe the septum of the nose (septum nasi) separating the two choanae. The fol- lowing are visible : (1) Nasopharyngeal meatus (meatus nasopharyngeus) . (2) Inferior meatus of nose (meatus nasi inferior). (3) Middle meatus of nose (meatus nasi medius). (4) Inferior turbinated bone (concha nasalis inferior). (5) Middle turbinated bone (concha nasalis media). FIG. 127. Fornix pharyngis Sinus sphenoidalis___ Concha nasalis media Meatus nasi medius Concha nasalis inferior Meatus nasi inferior i Palatum durum - Jlp Sulcus nasalis posterior^ Plica salpingopalatina Projection due to the M. leva tor veli palatini s Velum palatinum Paries lateralis pharyngis Fibrocartilago basalis Tonsilla pharyngea Bursa pharyngea (Var.) Fascia pharyngobasilaris Recessus pharyngeus _-( Rosen mu ell eri) Torus tubarius Ostium pharyngeum tubae auditivae Membrana atlanto- occipitalis anterior Plica salpingo- pharyngea —.Paries dorsalis pharyngis — fascia praeverte- fyralis _. JLrcus pharyngo- palatinus Medial aspect of right nasopharynx. (After Toldt, Anat. Atlas, Wien, 1900, 2 Aufl., p. 420, Fig. 686.) The posterior surface of the velum palatinum, the uvula, and the arcus pharyngopalatinus are to be examined; they have already been seen in front. Find the following : (h) Pharyngo-epiglottic fold (plica pharyngo-epiglottica) . (i) Aryepiglottic fold (plica aryepiglottica). (j) Opening into larynx (aditus laryngis) (vide Fig. 95). Observe the epiglottis guarding the opening. (k) Piriform recess (recessus piriformis) (0. T. sinus pyriformis). Foreign bodies often become lodged in this pocket. (ka) Fold of laryngeal nerve (plica nervi laryngei). Look for it in anterior part of recessus piriformis. Soft Palate (Palatum molle). (Vide Figs. 127 and 130.) The mucous membrane of this structure has already been viewed from the mouth; it is now to be studied also from the pharyngeal side. DISSECTION OF THE HEAD AND NECK 295 Make the velum palatinum tense by means of a hook and dissect the tunica mucosa off both its surfaces (oral and pharyn- geal) and also off the arcus glossopalatinus and the arcus phar- yngopalatinus. Observe the distribution of the glandulae pala- tinae. Study the form, position, origin, insertion, action, and inner- vation of each of the following : Muscles of the Palate and Fauces (Mm. palati et faucium). (Cf. Spalte- holz, Figs. 551 and 552.) (a) Glossopalatine muscle (M. glossopalatinus) (0. T. palatoglossus). (b) Pharyngopalatine muscle (M. pharyngopalatinus) (0. T. palato- pharyngeus). (Observe here the salpingopharyngeal muscle (M. salpingo- pharyngeus) ; it is really a part of the tunica muscularis pharyngis.) (c) Muscle of uvula (M. uvulae) (0. T. azygos uvulae). Now remove the wall of the pharynx between the Eustachian tube (tuba auditiva) above and the upper border of the M. con- strictor pharyngis superior below. Study — (d) Levator muscle of palatine curtain (M. levator veil palatini) (0. T. levator palati). (e) Tensor muscle of palatine curtain (M. tensor veil palatini} (0. T. tensor palati). Note especially the nerve supply of this muscle; also the bursa M. tensoris veli palatini. What is meant by the " palatal aponeurosis" ? Study also— Arteries. (a) Ascending palatine artery (A. palatina ascendens) (0. T. inferior palatine). Of what is it a branch? Where have you met it before ? (b) Pharyngeal rami of ascending pharyngeal artery (rami pharyngei A. pharyngeae ascendentis) (0. T. palatine branch of ascending pharyngeal). (c) Descending palatine artery from internal maxillary artery (A. palatina descendens). Veins. (a) Pharyngeal veins (Vv. pharyngeae), from pharyngeal plexus (plexus pharyngeus) to V. jugularis interna. (b) Palatine vein (V. palatina), corresponding to A. palatina ascendens and emptying into V. f acialis anterior. Nerves. (Figs. 12S and 132.) (a) Branches of N. accessorius (through the rami pharyngei N. vagi) to the M. levator palati, M. uvulae, M. pharyngopalatinus, and M. glossopalatinus. (b) Nerve of the palatine tensor (N. tensoris palatini), from motor part of N. trigeminus (through ganglion oticum) to the M. tensor veli palatini. 296 LABORATORY MANUAL OF HUMAN ANATOMY (c) Palatine nerves (Nn. palatini), from the N. trigeminus through the ganglion sphenopalatinum. (ca) Middle palatine nerve (N. palatinus medius) (0. T. exter- nal palatine). (cb) Posterior palatine nerve (TV. palatinus posterior}. Palatine Tonsils (Tonsillae palatinae). (Vide Spalteholz, Figs. 545- 548.) Observe the exact situation of the palatine tonsil on each side. How is it related to neighboring structures? What especial danger might be run in lancing a peritonsillar abscess ! (a) Tonsillar crypts or fossulae (fossulae tonsillares). Are any of them filled with yellowish- white plugs? (b) Tonsillar sinus (sinus tonsillaris). Is it completely filled by the tonsil or is there a fossa supratonsillarisf Note the plica triangu- laris. How is the tonsil supplied with blood? How is the tonsil related to the cervical lymph-glands? Auditory or Eustachian Tube (Tuba auditiva [Eustachii]). Of its two parts, one is lateral and bony (pars ossea tubae auditivae), the other medial and cartilaginous (pars cartilaginea tubae auditivae). The cartilaginous part is now studied. Its pharyngeal opening (ostium pharyngeum tubae auditivae) has already been examined. Pass a bristle or probe into it and ascer- tain the direction of the tuba auditiva. What is the position of the tuba as regards the M. levator veli palatini and the M. tensor veli palatini ? Dissect the mucous membrane cautiously away around the pharyngeal opening of the tube and examine the constitution of the cartilaginous portion. The cartilage of the Eustachian tube (cartilago tubae audi- tivae) consists of two laminae, one medial (lamina cartilaginis medialis) and one lateral (lamina cartilaginis lateralis). (Cf. Spalteholz, Fig. 552.) Where cartilage is lacking, a strong mem- branous layer (lamina membranacea) takes its place. Open the tuba auditiva and examine the mucous membrane (tunica mu- cosa). Are there any glands (glandulae mucosae) or solitary lymph-nodules (noduli lympJiatici tubarii) visible! Observe the trumpet-shape of the canal. From which of the inner branchial pockets of the embryo do the Eustachian tube and cavity of the middle ear arise? DISSECTION OF THE HEAD AND NECK 297 CAROTID AND INFRAORBITAL CANALS (CANALIS CAROTICUS ET CANALIS INFRAORBITALIS). Carotid Canal (Canalis caroticus). Remove the inferior wall of the carotid canal with strong forceps. Do not disturb the position of the Eustachian tube. Inside the carotid canal study the following : (a) Internal carotid artery (A. carotis internet). (Cf. Spalteholz, Fig. 442.) (aa) Caroticotympanic ramus (ramus caroticotympanicus) (0. T. tympanic branch). (b) Venous plexus of internal carotid (plexus venosus caroticus internus). (c) Internal carotid nerve of sympathetic system (N. caroticus internus). (Cf. Spalteholz, Figs. 773 and 779.) (ca) Internal carotid plexus (plexus caroticus internus). (caa) Deep petrosal nerve (N. petrosus profundus) (0. T. large, deep petrosal nerve), which runs to the pterygoid canal (0. T. Vidian canal) and unites with the N. petrosus superficialis major to form the nerve of the pterygoid canal (N. canalis ptery- goidei [Vidii]) (0. T. Vidian nerve). Infraorbital Canal (Canalis inf raorbitalis) . Remove the M. temporalis and the upper head of the M. pterygoideus externus ; saw through the squama temporalis and the ala magna oss. sphenoidalis, beginning on the cut margin of the skull just above the meatus acusticus externus and passing obliquely downward and forward towards the medial end of the fissura orbitalis superior (0. T. sphenoidal fissure). The saw-cut should enter the fissura orbitalis superior just lateral from the foramen rotundum. Make a second saw-cut from the cut margin of the cranial wall, just above the anterior margin of the ala magna oss. sphenoidalis, downward into the fissura orbitalis superior, to meet the first saw-cut. Remove the bone thus freed and with bone-forceps remove what remains of the ala magna lateral from the foramen rotundum, keeping intact, however, the entire bony margin of this aperture. Next open the canalis inf raorbitalis with bone-forceps (or chisel if necessary). Study the following: (a) Maxillary nerve (N. maxillaris) (0. T. superior maxillary). (Fig. 115, p. 274.) Trace it from the ganglion semilunare [Gasseri] to its termination. 298 LABORATORY MANUAL OF HUMAN ANATOMY (aa) Middle meningeal nerve (N. meningeus [medius]) (0. T. recurrent). This has been studied already within the cranium. (ab) Zygomatic nerve (N. zygomaticus) (0. T. orbital or temporo- malar). Already studied, with its two rami, in the orbit, .(ac) Sphenopalatine nerves (Nn. sphenopalatini) , going to the ganglion sphenopalatinum. (ad) Superior alveolar nerves (Nn. alveolares superiores). (ada) Posterior superior alveolar rami (rami alveolares superiores posteriores) (0. T. posterior superior dental). (ae) Infraorbital nerve (TV. infraorbitalis). (aea [also adb]) Middle superior alveolar ramus (ramus alveolaris superior medius) (0. T. mid- dle superior dental). (aeb [also adc]) Anterior superior alveolar rami (rami alveola? 3 s superiores anteriores) (0. T. anterior superior dental). How is the superior dental plexus (plexus den- dentalis superior) formed? Find — (1) Superior dental rami (rami dent ales supe- riores). (2) Superior gingival rami (rami gingivales superiores). The other terminal rami of the infraorbital nerve have been studied in the dissection of the face. (b) Infraorbital artery (A. infraorbitalis). Its origin has already been studied. Examine its course and — (ba) Anterior superior alveolar arteries (Aa. alveolares superiores anteriores) (0. T. anterior superior dental). SAGITTAL SECTION OF FOREPART OF HEAD NEAR MEDIAN PLANE. Remove the mandible, with the tongue and larynx, by making a cut backward from the angle of the mouth through the cheek, the raphe pterygomandibularis, and the lateral wall of the phar- ynx. Cut through also the vessels and nerves still connecting the pharynx with the skull. Wrap the larynx and tongue in moist cloth for subsequent dissection. Make a sagittal saw-cut through the forepart of the skull just lateral from the septum nasi; if the septum is not vertical, but deviates somewhat to one side, make the section close to the concave side of the septum. Before sawing, cut through the cartilaginous part of the nose as far as the nasal bone with a DISSECTION OF THE HEAD AND NECK 299 knife and cut through the soft palate in the same plane. Then saw through the bone from behind forward; the saw passes through the hard palate and the roof of the nose. FIG. 128. Ramus anastomoticus cum N. spinoso Portio minor -v Cms longum incudis Membrana tyrnpani^^ Chorda tympani N. petrosus superficial minor N. tensoris tympari M. tensor tympani \ N. trigemini Portio major j N. masticatorius Manubrium mallei N. facialis X N. auriculotemporalis Ganglion oticum X. tensoris veli palatini N. pterygoideus internus -N. pterygoideus externus ^..V. tensor veli palatini Ramus anastomoti- cus cum N. auriculo- temporali Ramus anastomoticus cum chorda tympani N. lingualis Plexus caroticus internus with its offshoots, the plexus maxillaris internus and meningeus , A. meningea media ! i_ , _ ,,„„„— ^-*^^, , N. alveolans infenor t. pterygoideus internus I. mylohyoideus The otic ganglion and its connections seen from the medial side. (After Toldt, Anat. Atlas, Wien, 1903, 3 Aufl., p. 867, Fig. 1307.) Radix sympathica of the Ganglion oticum Otic Ganglion (Ganglion oticum) (O. T. Ganglion of Arnold). (Fig. 128.) Place the sagittal cut surface upward ; detach the M. levator veli palatini at its origin and reflect it downward. Remove very cautiously the pars cartilaginea tubae auditivae; the otic gan- glion lies just beneath, between it and the N. mandibularis. A useful guide is the nerve to the M. pterygoideus internus ; follow it upward and backward to the otic ganglion. Find the fol- lowing i ' roots ' ' : (a) Short root: from the N. mandibularis. (b) Long root: lesser superficial petrosal nerve (N. petrosus super- ficialis minor) ; probably contains motor fibres from N. facialis and sensory fibres from N. glossopharyngeus. (c) Ganglionic or sympathetic root (radix sympathica} : from plexus in middle mening-eal artery. Branches of Distribution. (a) Nerve of tensor muscle of palatine curtain (N. tensoris veli pala- tini). 300 LABORATORY MANUAL OF HUMAN ANATOMY (b) Nerve of tensor muscle of tympanum (N. tensoris tympani). Connecting Branches. (a) With spinous nerve of mandibular nerve (ramus anastomoticus cum N. spinoso). (b) With auriculotemporal nerve of mandibular nerve (ramus anasto- moticus cum N. auriculotemporali) . (c) With chorda tympani (ramus anastomoticus cum chorda tympani). Cavity of Nose (Cavum nasi). (Vide Figs. 130 and 131.) Study- (a) Septum of nose (septum nasi). Remove the mucous membrane and examine — (aa) Cartilaginous septum (septum cartilagineum ) . (ab) Membranous septum (septum membranaceum) . Remove the cartilage and bones of septum piecemeal, avoiding injury to the mucous membrane of the opposite side of the septum. Find — N. nasopalatinus (Scarpae) FIG. 129. Nn. olfactorii (medial row) ;y--Bulbus olfactorius .Ramus nasalis internus (N. etnmoid- ant-) [Kami nasales f mediales Medial branches of the olfactory nerve (after Hirschfeld). (From Poirier et Charpy, Traite" d'Anat. hum., Paris, 1897, t. iii., 3, p. 775, Fig. 418.) (ac) Nerves of the septum nasi. (aca) Olfactory nerves (Nn. olfactorii). (acb) Medial superior posterior nasal rami (rami nasales posterior es superior es mediales). (acba) Nasopalatine nerve (N. nasopalatinus [Scarpae]) (0. T. nerve of Cotun- DISSECTION OF THE HEAD AND NECK 301 nius), from the sphenopalatine gan- glion. (ace) Medial nasal rami of internal nasal rami of ante- rior nasal rami of N. nasociliaris (rami nasales mediates) (O. T. septal branch of nasal nerve). (ad) Arteries going to the septum. Of what are they branches? Now cut through the tunica mucosa septi, with scissors, along the roof of the nasal cavity and reflect it; the nasopalatine nerve and medial nasal rami are to be preserved for further examination. FIG. 130. Concha nasalis media Concha nasalis superior : Meatus nasi superior • Apertura sinus sphenoidalis | i Meatus nasi medius Recessus sphenoethmoidalis Hypophysis Sinus sphenoidalis Fomix pharyngis Synchondrosis spheno-occipi talis Sulcus nasalis posterior Sinus frontalis Agger nasi Plica salpingo- — palatina Torus tubarius—- Ostium pharyngeum tubae auditivae Levator prominence -^ Plica salpingo- ^ pharyngea Velum palatinum Atrium meatus nasi medii Cartilage nasi lateralis Limen nasi Vestibu- lum nasi Cartilago alaris major (Cms mediale) Remnant of the cartilage of the lateral wall Concha nasalis inferior Meatus nasi inferior Medial aspect of the left wall of the nasal cavity (After Toldt, Anat. Atlas, Wien, 1903, 3Aufl., p 944, Fig 1473.) (b) Anterior apertures (nares). (c) Posterior apertures (choanae). (d) Vestibule of nose (vestibulum nasi). (da) Hairs in vestibule (vibrissae). (e) Threshold of nose (limen nasi). (f) Olfactory sulcus (sulcus olfactorius) . (g) Conchae (0. T. turbinated bones). (ga) Superior nasal concha (concha nasalis superior) (0. T. supe- rior turbinated bone). (gb) Middle nasal concha (concha nasalis media) (0. T. middle turbinated bone). 302 LABORATORY MANUAL OF HUMAN ANATOMY (*) (gc) Inferior nasal concha (concha nasalis inferior) (0. T. infe- rior turbinated bone). Is a highest nasal concha (concha nasalis suprema [San- torini]) present? Observe the mucous membrane of the nose (membrana mucosa nasi). Over the concha there is much erectile tissue (plexus cavernosi concharum). What is the spheno-ethmoidal recess (recessus spheno-ethmoid- alis) ? The agger ("elevation") of the nose (agger nasi) (0. T. rudiment of anterior turbinal). FIG. 131. Infundibulum ethmoidale with the apertura sinus maxillaris Opening of the labyrinthus ethrnoidalis \ Recessus sphenoethmoidalis Apertura sinus sphenoidalis > Concha nasalis superior Sinus sphenoidalis Meatus nasi superior- Concha nasali media (partly removed) Sulcus nasalis ' posterior Torus tubarius — Ostium pharyn- — geum tubae auditivae Levator prominence Bulla ethmoidalis Velum palatinum M. thyreoarytaenoideus (externus) Pars intennembranacea rimae glottidis M. vocalis .Pars interoartOacinea rimae glottidis Cartilago arytaenoidea (processus vocalis) Both sections of a larynx cut transversely across in the region of the ventricle. The mucous membrane has been removed from the right side of the lower section. (After Toldt, Anat. Atlas, Wien, 1900, 2 Aufl., p. 445, Fig. 757.) On each side of the aditus glottidis superior is situated the ventricle of the larynx (ventriculus laryngis [Morgagnii}) (O. T. laryngeal sinus), with its blind sac-like appendage, appendix ventriculi laryngis (O. T. laryngeal pouch or sac). The true vocal cord, or vocal fold (plica vocalis) on each side, is the free margin of the three-sided prismatic projection known as the vocal lip (labium vocale). Note that the plica vocalis is situated farther medialward than the plica ventricularis. Ob- serve near the anterior extremity of the plica vocalis the " yel- low spot" (macula flava). To what is this due? 310 LABORATORY MANUAL OF HUMAN ANATOMY Glottis. The two plicae vocales together form the glottis (O. T. glottis vera), the slit between them being known as the rima glottidis. The rima glottidis is divisible into— (a) Intermembranous part (pars intermembranacea) (0. T. glottis vo- calis), the anterior longer part, between the plicae vocales. (b) Intercartilaginous part (pars intercartilaginea) (0. T. glottis respira- toria), the posterior shorter part, between the medial surfaces of the arytaenoid cartilages. The cavity below the rima glottidis — i.e., the inferior cavity of the larynx — is called the aditus glottidis inferior. It leads below into the trachea. Mucous Membrane of the Larynx (Tunica mucosa laryngis). Observe— (a) Mucous laryngeal glands (Gl. laryngeae). (aa) Anterior (GL laryngeae anteriores), in front of and behind the epiglottis. (ab) Middle (GL laryngeae mediae), on the plicae ventriculares, in the ventricles, and around the cuneiform cartilages. (ac) Posterior (GL laryngeae posteriores) , in front of, in, and behind the M. arytaenoideus transversus. (b) Lymph-nodules of larynx (noduli lymphatici solitarii), especially on the posterior surface of the epiglottis and in the ventricles. Hyothyreoid Membrane and Laryngeal Muscles. With a probe stuff the ventricle of the larynx and its appen- dix full of moist cotton. Fasten the larynx with pins on a wooden block, the anterior surface upward. Find the ramus externus and ramus internus of the N. laryn- geus superior, the N. recurrens, the superior and inferior laryn- geal vessels, and avoid injury to them in the subsequent dissec- tion. Eemove the Gl. thyreoidea and the Mm. omohyoideus, sternohyoideus, sternothyreoideus, thyreohyoideus, and con- strictor pharyngis inferior. Clean and study the following structures : (a) Hyothyreoid membrane (membrana Jiyothyreoidea) (0. T. thyro- hyoid membrane). Observe how it is perforated by the A. and V. laryngea superior and by the ramus internus N. laryngei superioris. (aa) Middle hyothyreoid ligament (ligamentum Jiyofhyreoideum medium). (ab) Lateral hyothyreoid ligament (ligamentum hyothyreoideum laterale). DISSECTION OF THE HEAD AND NECK 311 (aba) Wheat-like or triticeous cartilage (cartilago triticea). (b) Cricothyreoid muscle (M. cricothyreoideus}. (ba) Straight part (pars recta) (0. T. anterior or oblique part). (bb) Oblique part (pars obliqua) (0. T. posterior or horizontal part). Study its origin, insertion, action, and innervation. (c) Middle cricothyreoid ligament (ligamentum cricothyreoideum [me- dium]) (0. T. middle portion of cricothyreoid membrane). This is really a part of the conus elasticus (vide infra). Reverse position of larynx on wooden block, so that posterior surface looks upward. Slit open oesophagus along middle line behind. Dissect the tunica mucosa cautiously off the posterior aspect of the cricoid and arytaenoid cartilages, avoiding injury to the A. laryngea inferior and N. recurrens (between thyreoid and cricoid cartilages). Clean carefully the following muscles and ascertain their form, position, origin, insertion, action, and innervation : (a) Posterior cricoarytaenoid muscle (M. cricoarytaenoideus posterior). (b) Oblique arytaenoid muscle (M. arytaenoideus obliquus). (ba) Aryepiglottic muscle (M. aryepiglotticus) (0. T. aryteno- epiglottidean muscle). (c) Transverse arytaenoid muscle (M. arytaenoideus transversus) . From this point on, the dissection is conducted differently on the two sides, that on the right being made especially for the muscles, that on the left for the vessels and nerves. Fasten larynx by its left side to the wooden block. Remove the M. cricothyreoideus of the right side. Cut through the right ligamentum hyothyreoideum laterale; disarticulate the right inferior cornu of thyreoid cartilage from the facies articularis thyreoidea on the side of the cricoid cartilage. Cut vertically through the lamina dextra of the thyreoid cartilage a little lat- eral from the anterior median line and remove the detached right lamina. Clean carefully and study the form, position, origin, inser- tion, action, and innervation of the following muscles : (a) Lateral crico-arytaenoid muscle (M. cricoarytaenoideus later alls}. (b) Thyreo-arytaenoid muscle (M. thyreoarytaenoideus [externus]). (c) Thyreo-epiglottic muscle (M. thyreoepiglotticus) (0. T. thyro-epi- glottidean muscle). (d) Vocal muscle (M. vocalis) (0. T. internal thyro-arytenoid muscle). (This muscle is best seen in a cross-section through the whole larynx at the level of the true vocal cord. It lies medial from the 312 LABORATORY MANUAL OF HUMAN ANATOMY M. thyreoarytaenoideus [externus], the two being scarcely sep- arable. ) (e) Ventricular muscle (M. ventricularis) . This is a minute muscle in the plica ventricularis, scarcely to be made out except with the aid of the microscope. Eemove cautiously the M. cricoarytaenoideus lateralis and try to separate the M. thyreoarytaenoideus [externus] from the more medially situated M. vocalis. Ascertain the relation of the latter to the labium vocale and then remove it. Study the parts now exposed. FIG. 136. Bundle of the M. stylopharyngeus XSB&X M. aryepiglotticus Glandulae laryngeae mediae _ Tunica mucosa laryngis ^ Mm. arytaenoidei obliqui _ M. arytaenoideus transversus — M. cricothyreoideus — Articulatio cricothyreoidea M. crico-arytaenoideus posterior M. ceratocricoideus (Var.) Muscles of larynx seen from behind. Part of the right lamina of the thyreoid cartilage has been removed. (After Toldt, Anat. Atlas, Wien, 1900, 2 Aufl., p. 444, Fig. 751.) Elastic Membrane of Larynx (Membrana elastica laryngis). (a) Elastic cone (conus elasticus} (0. T. cricothyroid membrane). (aa) Vocal ligament (ligamentum vocale} (0. T. inferior thyro- arytenoid ligament). Observe that this is really the upper free thickened border of the conus elasticus. Note especially its anterior and posterior attachments. Between the two ligamenta vocalia in front observe — (aaa) Sesamoid cartilage (cartilago sesamoidea}. (b) Quadrangular membrane (membrana quadrangularis) . (ba) Ventricular ligament (ligamentum ventriculare) (0. T. superior thyro-arytenoid ligament). DISSECTION OF THE HEAD AND NECK 313 Observe that this ligament is simply the thickened lower margin of the quadrangular membrane. Next dissect away on the right side the remains of the plica aryepiglottica, membrana quadrangularis, plica ventricularis, plica vocalis, and comis elasticus, but leave the arytaenoid and corniculate cartilages undisturbed. Remove the cuneiform car- tilage from the right aryepiglottic fold and preserve it for subse- quent study. The left wall of the cavity of the larynx may now be thoroughly studied, and any points not well made out in the preliminary study of the cavity before it was opened should be cleared up before going further. Vessels and Nerves of Larynx. The dissection of the vessels and nerves of the interior of the larynx should now be undertaken. (a) Internal ramus of superior laryngeal nerve (ramus internus 'N. laryn- gei superioris). (aa) Ramus anastomosing with inferior laryngeal nerve (ramus anastomoticus cum N. laryngeo inferiore) (0. T. Galen's loop). Make traction on this nerve outside the larynx where it pierces the membrana hyothyreoidea and cut through the tunica mucosa laryngis on the inner surface of this mem- brane and find the nerve and artery. Gradually dissect off the tunica mucosa and expose their branches. What is the function of the internal ramus of the N. laryngeus superior ? (b) Inferior laryngeal nerve from the recurrent nerve (N. laryngeus in- ferior N. recurrentis) (0. T. recurrent laryngeal nerve). To see it well, draw the thyreoid cartilage well lateral- ward. (ba) Anterior ramus (ramus anterior). What muscles are innervated by it ? (bb) Posterior ramus (ramus posterior). What muscles does it supply? (c) Superior laryngeal artery (A. laryngea superior). (d) Inferior laryngeal artery (A. laryngea inferior). Cartilages and Ligaments of Larynx. Some of these have already been examined. Remove the rest of the mucous membrane and the muscles from the cartilages, taking care not to injure the ligaments or the smaller cartilages. Study— Epiglottis and its Ligaments, (a) Epiglottis. Stem of epiglottis (petiolus epiglottidis) . 314 LABORATORY MANUAL OF HUMAN ANATOMY (ab) Epiglottic tubercle (tuberculum epiglotticum) (0. T. cushion of epiglottis). (ac) Epiglottic cartilage (cartilago epiglottica) . '(&) Thyreo-epiglottic ligament (ligamentum thyreoepiglotticum) (0. T. thyro-epiglottidean ligament), (c) Hyo-epiglottic ligament (ligamentum hyoepiglotticum) (0. T. hyo- epiglottidean ligament). Thyreoid Cartilage (Cartilago thyreoidea}. (a) Right and left plates (laminae [dextra et sinistra]) (0. T. ala). (b) Superior thyreoid notch (incisura thyreoidea superior). (c) Inferior thyreoid notch (incisura thyreoidea inferior). (d) Superior thyreoid tubercle (tuberculum thyreoideum superius). (e) Inferior thyreoid tubercle (tuberculum thyreoideum inferius). (f) Oblique line (linea obliqua). (g) Superior horn (cornu superius). (h) Inferior horn (cornu inferius). (i) Thyreoid foramen (foramen thyreoideum). Cricothyreoid Joint (Articulatio cricothyreoidea) . (a) Capsule of joint (capsula articularis cricothyreoidea). (b) Lateral ceratocricoid ligaments (Ligg. ceratocricoidea lateralia}. (c) Anterior ceratocricoid ligament (Lig. ceratocricoideum anterius). (d) Posterior ceratocricoid ligaments (Ligg. ceratocricoidea posteriora). Divide the structures connecting the thyreoid cartilage to the cricoid and remove the former. Cricoid Cartilage (Cartilago cricoidea). (a) Arch (arcus [cartilaginis cricoideae]) . (b) Lamina (lamina [cartilaginis cricoideae]). (c) Arytaenoid articular surface (fades articularis arytaenoidea) . (d) Thyreoid articular surface (fades articularis thyreoidea). Observe also the cricotracheal ligament (ligamentum crico- tracheale). Corniculate Cartilage (Cartilago corniculata [Santorini]) (0. T. carti- lage of Santorini). (a) Arycorniculate joint (synchondrosis arycorniculata) . (b) Corniculopharyngeal ligament (Lig. corniculopharyngeum) (0. T. Lig. jugale). (ba) Cricopharyngeal ligament (Lig. cricopharyngeum) . Arytaenoid Cartilage (Cartilago arytaenoidea). Remove one in order to study the cartilage itself; leave the other in situ for the study of the ligaments. (a) Tip or apex (apex [cartilaginis arytaenoideae]). (b) Base (basis [cartilaginis arytaenoideae]). (ba) Articular surface (fades articularis). (c) Posterior surface (fades posterior). (d) Medial surface (fades medialis) (0. T. internal surface). (e) Lateral surface (fades lateralis) (0. T. antero-external surface). (ea) Nodule or hillock (colliculus) . (eb) Arched ridge (crista arcuata). (ec) Triangular depression (fovea triangularis) . (ed) Oblong depression (fovea oblonga). DISSECTION OF THE HEAD AND NECK 315 (/) Vocal process (processus vocalis). (g) Muscular process (processus muscularis). Cuneiform Cartilage (Cartilago cuneiformis [Wrisbergi] ). Was this present on each side in the subject under dissection? Crico-arytaenoid Joint (Articulatio cricoarytaenoidea). (a) Joint-capsule (capsula articularis cricoarytaenoidea). (b) Posterior crico-arytaenoid ligament (Lig. cricoarytaenoideum pos- terius). The student is advised to read at this juncture on the physi- ology of voice-production and to study the action of the various laryngeal muscles. Why does food not enter the larynx during deglutition? TONGUE (LINGUA). Examine the following : (a) Back of tongue (dorsum linguae). (b) Root of tongue (radix linguae). To what is it attached? (Vide Figs. 125, 137.) FIG. 137. Epiglottis^ Plica glossoepiglottica mediana Vallecula epiglottica Plica glossoepiglottica ~ lateralis Foramen caecum linguae (Morgagnii) Sulcus terminalis^ linguae Papillae lenticulares-----'- Papillae vallatae-*1"^" Papillae foliatae-=.-— Papillae conicae- ' Papillae fungiformes Papillae filiformes^- Radix linguae Tonsilla lingualis Folliculi linguales Tonsilla palatina (in horizontal cross-section) -Sinus tonsillaris Plica triangularis Arcus glossopalatinus Corpus linguae (dorsum) -Margo lateralis linguae ._Sulcus medianus linguae -Apex linguae Dorsal surface of tongue. (After Toldt; Anat. Atlas, Wien, 1900, 2 Aufl., p. 403, Fig. 649.) (c) Body of tongue (corpus linguae). (d) Inferior surface (fades inferior [linguae]). (da) Fimbriated fold (plica fimbriata). 316 LABORATORY MANUAL OF HUMAN ANATOMY (e) Tip of tongue (apex linguae). (f) Mucous membrane of tongue (tunica mucosa linguae). This has already been studied in connection with the mouth cavity, but should now be reviewed. (fa) Frenuluni ("bridle" or "check-rein") of tongue (frenulum linguae). (fb) Lingual papillae (papillae linguales). (fba) Filiform papillae (papillae filiformes). (fbb) Conical papillae (papillae conicae). (fbc) Fungiform papillae (papillae fungiformes). (fbd) Lenticular papillae (papillae lenticular -e s) . (fbe) Vallate papillae (papillae vallatae) (0. T. cireum- vallate). (fbf) Foliate papillae (papillae foliatae). (g) Median sulcus of tongue (sulcus medianus linguae), (h) Terminal sulcus (sulcus terminalis) . FIG. 138. M. verticalis linguae M. transversus linguae Fascia linguae -*-M. longitudinalis superior Glandula lingualis anterior (Blandini, Nuhni) Plica fimbriata Facies inferior linguae Septum linguae Transverse section through the tongue near the tip. (After Toldt, Anat. Atlas, Wien, 1900, 2 AufL, p. 405, Fig. 652. (t) Blind foramen of tongue (foramen caecum linguae [Morgagnii]). (ia) Lingual duct (ductus lingualis). (iaa) Thyreoglossal duct (ductus thyreoglossus). (j) Lingual tonsil (tonsilla lingualis). (ja) Lingual folliculi (folliculi linguales). (k) Muscles of tongue. Remove the tunica mucosa linguae from the right side of the tongue; isolate the individual muscles and review their form, posi- tion, origin, insertion, action, and innervation. Extrinsic muscles (vide Fig. 112) : (ka) Genioglossus muscle (M. genioglossus). (kb) Hyoglossus muscle (M. hyoglossus). (kc) Chondroglossus muscle (M. chondroglossus). (kd) Styloglossus muscle (M. styloglossus) . Intrinsic muscles (vide Fig. 138) : (ke) Superior longitudinal muscle of tongue (M. longitudinalis superior linguae) (0. T. superficial lingual). (kf) Inferior longitudinal muscle of tongue (M. longitudinalis in- ferior linguae) (0. T. inferior lingual). DISSECTION OF THE HEAD AND NECK 317 (kg) Transverse muscle of tongue (M. transversus linguae), (kh) Vertical muscle of tongue (M. verticalis linguae). (I) Septum of tongue (septum linguae), (m) Nerves of tongue (to be studied on left side of tongue). (ma) Glossopharyngeal nerve (N. glossopharyngeus). (maa) Lingual rami (rami linguales). (mb) Lingual nerve (N. lingualis). (mba) Sublingual nerve (N. sublingualis) . (mbb) Lingual rami (rami linguales). Read on the relations of the N. trigeminus and the N. intermedius, respectively, to the N. lingualis. (me) Hypoglossal nerve (N. hypoglossus) . (mca) Lingual rami (rami linguales). What do they innervate? (n) Lingual artery (A. lingualis). (na) Dorsal rami of tongue (rami dor sales linguae), (nb) Deep artery of tongue (A. profunda linguae) (0. T. ranine artery). BRAIN (ENCEPHALON). The student should now undertake the systematic study of the brain. Membranes of Brain (Meninges encephali). (a) Dura mater of the brain (dura mater encephali). This has been examined before (p. 198). (b) Arachnoid of brain (arachnoidea encephali). (ba) Subarachnoid cavity (cavum subarachnoideale) . (bb) Subarachnoid cisterns (cisternae subarachnoideales) . Divide the arachnoid in the middle line over the anterior surface of the medulla oblongata and pons, and turn the two halves lateralward. (bba) Cerebellomedullary cistern (cisterna cerebellomedul- laris) (0. T. cisterna magna). (bbb) Cistern of the lateral fossa of the cerebrum (cis- terna fossae lateralis cerebri [Sylvii]). Note relation to A. cerebri media. . (bbc) Cistern of the chiasm (cisterna chiasmatis). (bbd) Interpeduncular cistern (cisterna interpeduncularis) (0. T. cisterna basalis). (bbe) Cistern of the large veins of the cerebrum (cisterna venae magnae cerebri). (be) Arachnoideal granulations (granulationes arachnoideales [Pacchioni]) (0. T. Pacchionian bodies).. (Vide Fig. 84.) (c) Pia mater of brain (pia mater encephali). Study this in its relation to the surface of the brain. The portions of the pia in the interior of the brain will be studied later on. 318 LABORATORY MANUAL OF HUMAN ANATOMY FIG. 139. in -vm ncl Cerebrum, with a portion of the spinal cord, viewed from the ventral surface. On the right-hand side the ventral roots are cut off short and turned medialward. I, tractus olfactorius ; II, tractus opticus ; III, N. oculomotorius ; IV, N. trochlearis ; V, N. trige- minus, portio major et portio minor; VI, N. abducens; VII, N. facialis ; Vir, N. intermedius; VIII, N. acusticus ; IX, N. glossopharyngeus ; X, N. vagus ; XI, N. accessorius ; XII, N. hypoglossus ; nc I, N. cervicalis primus. (After Rudinger and Henle, from A. Rauber's text-book.) Blood-vessels of Brain. (Vide Fig. 140.) Remove the arachnoidea encephali from the base of the cere- brum and from the anterior surface of the rhombencephalon. With scissors and forceps follow the blood-vessels, beginning at DISSECTION OF THE HEAD AND NECK 319 the large trunks and passing out to the finer subdivisions. Do not injure the brain substance. FIG. 140. The arteries of the base of the brain. T, lobus temporalis (cut off) ; T-XII, Nn. cerebral es; Accra, art. cerebri anterior; Coma, art. com- municans anterior ; A FSy, art. cerebri media ; A lent, art. lenticularis ; 1-5, the cortical chief branches of the A cer. med. ; cp, art. communicans posterior ; A cha, art. chorioidea ; ch, a small branch of the preceding which goes into the plexus chorioidei ; x, lateral branches of the A. com. post. ; A cp, art. cerebri posterior ; p, short branches of the preceding ; A bas, art. basilaris ; A t, art. temporalis (Duret) ; Aocc, art. occipitalis (Duret) ; JUvr»v//>. art. cerebelli superior; A cer med, art. cerebelli inferior ante- rior; A cerinf, art. cerebelli inferior posterior : .1 n rf, art. vertebralis; Spa, art. spinalis anterior. (After Monakow, Gehirnpathologie, Wien, 1897, p. 668, Fig. 151.) Arteries. (a) Vertebral artery (A. vertebralis). (aa) Posterior spinal artery ( A. spinalis posterior). (ab) Anterior spinal artery (A. spinalis anterior). 320 LABORATORY MANUAL OF HUMAN ANATOMY (ac) Meningeal ramus (ramus meningeus) (0. T. posterior nien- ingeal branch). (ad) Posterior inferior cerebellar artery (A. cerebelli inferior posterior), (b) Basilar artery (A. basilaris). (ba) Anterior inferior cerebellar artery (A. cerebelli inferior anterior). (bb) Internal auditory artery (A. auditiva interna) (0. T. auditory artery). (be) Rami to pons (rami ad pontem) (0. T. transverse arteries). (bd) Superior cerebellar artery (A. cerebelli superior). (be) Posterior cerebral artery (A. cerebri posterior). (bf) Arterial circle of Willis (circulus arteriosus [Wittisi]). Lateral view of the right hemisphere with the distribution of the A. cerebri media. Art. FS, art. cer. med. ; I, II, III, IV, V, the five chief branches of the preceding ; Ilia, lateral twigs of the third branch of the A. cer. med. ; Fc, sulcus centralis ; FS, fissura cerebri lateralis [Sylvii] ; JP, sulcus interparietalis ; t, sulcus temporalis superior ; F^-Fy, superior, middle and inferior frontal gyri ; SM, gyrus supramarginalis ; Ang, gyrus angularis ; Oi-03, gyri occipitales laterales. The dotted line indicates the extent of the distribution of the A. cer. med. (After v. Monakow, Gehirnpath., Wien, 1897, p. 673, Fig. 154.) (c) Internal carotid artery (A. carotis interna). (ca) Posterior communicating artery (A. communicans poste- rior). (cb) Chorioid artery (A. chorioidea) (0. T. anterior choroidal). (cc) Anterior cerebral artery (A. cerebri anterior). (cca) Anterior communicating artery (A. communicans anterior). DISSECTION OF THE HEAD AND NECK 321 (cd) Middle cerebral artery (A. cerebri media) (0. T. arteria fossae Sylvii). (Vide Figs. 140-142.) Distinguish between basal and central branches and cortical branches of the cerebral arteries. Why should emboli pass more Pare Gcp fo> Ch Frontal section through the right cerebral hemisphere (plane of the gyms centralis and chiasma opticum). Origin and course of the A. lenticularis as well as of the cortical branches of the A. cer- ebri media, schematically shown. Gca, anterior, Gcp, posterior central gyrus; Pare, lobulus paracentralis ; T]-T4, first to fourth tem- poral gyrus; S, corpus callosum; Am, nucleus amygdalae ; J, island; 7-X tissura rcrrbri latrralis [Sylvii] ; Li, nucleus lenticularis ; Thai, thalamus ; CH, gyrus hippocampi ; /, field of the A. cer. ant. ; //, of the A. cer. med. ; III, of the A. cer. post. The dotted lines show the boundaries between these. Ch, chiasma opticum ; Car, A. cer. inf. ; 1, stem of the A. cer. med. ; ta, course to the island is shown l>y dotted outline ; 2, lenticulo-striate arteries ; 5, lenticulo-optic arteries ; £, cortical branches of the A. cer. med. ; £a, medullary branches of the cortical twigs of the A. cer. med. (After v. Monakow, Gehirn- path., Wien, 1897, p. 674, Fig. 155.) frequently into the middle cerebral than into the anterior cere- bral artery! The " artery of cerebral hemorrhage " (Charcot), 21 322 LABORATORY MANUAL OF HUMAN ANATOMY so called on account of the frequency of its involvement, as com- pared with the other cerebral arteries, is one of the lenticular branches of the A. cerebri media. For a full description of the cerebral arteries and their relation to cerebral hemorrhages, see v. Monakow, Gehirnpathologie, pp. 667-792. Veins (Venae cerebri). Superficial. (a) Superior cerebral veins (Vv. cerebri superiores). (b) Middle cerebral vein (V. cerebri media}. (c) Inferior cerebral veins (Vv. cerebri inferiores). (d) Superior cerebellar veins (Vv. cerebelli superiores). (e) Inferior cerebellar veins (Vv. cerebelli inferiores). (f) Basal vein (V. basalis [Bosenthali]) . Deep. — These may be studied later. Removal of Meninges and Superficial Blood-vessels. Place the brain on the table, with the base upward. With forceps and scissors, cautiously remove the membranes and blood-vessels from the surface. The pia over the medulla oblon- gata and lower part of pons may be left until after the cerebral nerves have been identified and studied. The base of the brain is now exposed, including a part of the basis cerebri and the inferior (anterior) surfaces of the pons, medulla oblongata, and cerebellum. Observe— (a) Longitudinal fissure of cerebrum (fissura longitudinalis cerebri}. (b) Lateral fissure of cerebrum (fissura cerebri lateralis [Sylvii]) (0. T. fissure of Sylvius). (c) Temporal pole (polus temporalis). (d) Optic chiasm (chiasma opticum) with optic nerves (Nn. optici) and optic tracts (tractus optici). (e) Hypophysis (hypophysis) (0. T. pituitary body). This may have been left in the sella turcica. (f) Infundibulum (infundibulum) ("funnel"). (g) Ash-like tuber (tuber cinereum). (h) Mammillary bodies (corpora mammillaria) . (i) Cerebral peduncles (pedunculi cerebri) (0. T. crura cerebri). (j) Interpeduncular fossa (fossa inter peduncularis [Tarini]). (ja) Anterior recess (recessus anterior). (jb) Posterior recess (recessus posterior). (fr) Posterior perforated substance (substantia perforata posterior). (I) Pons (pons [Varolii]) ("bridge"). (m) Medulla oblongata. Cerebral Nerves (Nn. cerebrales). (Figs. 139 and 143.) The " superficial origins" of the cerebral nerves— i.e., their regions of exit from or entrance into the brain — may now be examined. DISSECTION OF THE HEAD AND NECK 323 I. Olfactory nerves (Nn. olfactorii). Do not confuse these with the olfactory tracts. Try to find the fine threads of the Nn. olfactorii penetrating- the ventral surface of each bulbus olfactorius. They come from the nasal mucous membrane, through the lamina cribrosa of the ethmoid bone. II. Optic nerve (N. opticus). It runs from the back of the eyeball to the optic chiasm. The student's later studies will show him that the optic nerve is really not a peripheral nerve, like the other cerebral nerves, but rather a part of the central nervous system. Gyrus rectus \ FIG. 143. Fissura longitudinalis cerebri Trigonum olfactorium N. opticus^ Chiasma opticum Corpus mammillare Uncus (gyri hippocampi) v N. oculomotorius Pedunculus cerebri Substantia perforata posterior (Fossa interpeduncularis) T\ (Pons Varolii) N. trigeminus ~i_ N. abducens N. facialis .. N. intermedius N. acustieus N. hypoglossus Pyramis (medullae oblongatae) Radix anterior N. cervicalis I. " Fissura mediana anterior Decussatio pyramidum Tractus olfactorius „ Stria olfactoria medialis Stria olfactoria intermedia Stria olfactoria lateralis '£ Substantia perforata anterior ^ — — Tuber cinereum and infundibulum — Tractus opticus - - Sulcus n. oculomotorii ^ Radix lateralis •> tractus ~~- Radix medialis) optici v Corpus geniculatum laterale — Fasciculus obliquus (pontis) -^. Sulcus basilaris - Brachium pontis Foramen caecum " Oliva Corpus restiforme Fibrae arcuatae externae Sulcus lateralis anterior Funiculus lateralis The medulla oblongata, pons (Varolii), cerebral peduncles, and part of the floor of the midbrain. Seen from the basal surface. (After Toklt, Anal. Atlas, Wien, 1903, 3 Aufl., p. 765, Fig. 1174.) III. Oculomotor nerve (N. oculomotorius). Look for it in the fossa inter- pedunculnris. It belongs to the midbrain. IV. Trnclilear nerve (X. t rochlearis) . While all the other cerebral nerves emerge from the ventral aspect of the brain-stem, this nerve emerges on the dorsal aspect. Its exact origin will be seen later. Note that it is on the lateral aspect of the pedunculus cerebri, while the oculomotor nerve is on the medial aspect of that structure. V. Trigeminal nerve (XT. Irigeminus). (a) Larger portion (portio major], sensory. (b) Smaller portion (portio minor}, motor. 324 LABORATORY MANUAL OF HUMAN ANATOMY VI. Abducent nerve (N. abducens). Emerges on each side at the junction of the pons with the medulla oblongata. VII. Facial nerve (N. facialis). (a) Intermediate nerve (N. intermedius) (0. T. pars intermedia, or nerve of Wrisberg). VIII. Acoustic nerve (N. acusticus) (0. T. auditory nerve). (a) Vestibular root (radix vestibularis) . This runs medial to the restiform body. (b) Cochlear root (radix cochlearis). This runs lateral from the restiform body. IX. Glossopharyngeal nerve (N. glossopharyngeus) . It may be difficult to decide exactly how many fila radicularia belong to this nerve and how many to X. and XI. X. Vagus nerve (N. vagus) (0. T. pneumogastric nerve). XL Accessory nerve (N. accessorius) (0. T. spinal accessory). XII. Hypoglossal nerve (N. hypoglossus) . Emerges between the oliva and the pyramis, by several fasciculi (fila radicularia). Larger Subdivisions of the Brain. Note the subdivision into rhomboid brain (rhombencephalon) and cerebrum, the junction being that between pons and mid- brain. The rhombencephalon includes — (a) After-brain (myelencephalon) (" medullary brain"). (b) Hind-brain (metencephalon), subdivisible into — ( ba ) Cerebellum. (bb) Pons [Varolii]. The cerebrum includes— (a) Midbrain (mesencephalon) . (b) Forebrain (prosencephalon), consisting of— (ba) Interbrain (diencephalon) and (bb) End-brain (telencephalon) . Examine carefully the longitudinal fissure of the cerebrum (fissura longitudinalis cerebri) (0. T. great longitudinal fissure). The following table shows the derivatives of the three cere- bral vesicles. DISSECTION OF THE HEAD AND NECK 325 H » § - ombencep Lozenge-sha Rh § •a •a I R g Metencephalon § T 31 & j o a f3 t^- § I E ( Hvpo- rs nptica g .y I 1 C -^ = = — 1 - — — ± — r 5 ~ q JOTJOJSOJ -9J90 ajppijn v ja;) JQIJ 326 LABORATORY MANUAL OF HUMAN ANATOMY The student may now remove one cerebral hemisphere (hemi- sphaerium cerebri). With a very sharp, thin knife, cut through the right cerebral peduncle just behind the right corpus mam- millare. Turn the brain over ; press the two hemispheres apart by widening the longitudinal fissure of the cerebrum; expose the corpus callosum and cut through it and the tissues beneath, as near the middle line as possible, or a very little to the left of it, so as to leave the septum pellucidum on the right hemisphere. Carry the incision backward to meet the transverse incision already made through the cerebral peduncle. This right hemi- sphere may be kept in the preserving fluid while the rest of the brain is being studied. External Morphology of Rhomboid Brain and Midbrain (Rhombencephalon and Mesencephalon). Lift the cerebellum gently from behind and observe the rela- tion of its inferior surface to the medulla oblongata and ven- triculus quartus. With a sharp, thin brain-knife, cut through the cerebellum in the middle line of the worm (vermis). Do no injury to the floor of the fourth ventricle, but permit the incision to pass forward through the anterior medullary velum as far as the inferior colliculi of the midbrain. Cut through the three cerebellar peduncles on the right side, — the superior peduncle (brachium conjunctivum) , the middle peduncle (brachium pon- tis), and the inferior peduncle (corpus restiforme). Eemove the right half of the cerebellum and preserve it for further study. Make three drawings showing anterior, lateral, and poste- rior views of rhombencephalon, and illustrating the following structures : Medulla Oblongata. (a) Anterior median fissure (fissura mediana anterior}. (b) Posterior median fissure (fissura mediana posterior). (c) Blind foramen (foramen caecum). (d) Pyramid (pyramis [medullae oblongatae] ). (e) Decussation of pyramids (decussatio pyramidum). (f) Anterior lateral sulcus (sulcus lateralis anterior}. (g) Posterior lateral sulcus (sulcus lateralis posterior), (h) Olive (oliva) (0. T. olivary eminence). (i) Restiform body (corpus restiforme) (0. T. inferior cerebellar peduncle). (j) Lateral funiculus (funiculus lateralis). (k) Cuneate funiculus (funiculus cuneatus) (0. T. column of Bur- dach). DISSECTION OF THE HEAD AND NECK 327 (I) Gray or ashen tubercle (tuberculum cinereum) (0. T. tubercle of Rolando). (m) Slender funiculus (funiculus gracilis) (O. T. column of Goll). (ma) Club (clava). (n) External arcuate fibres (fibrae arcuatae externae) (O. T. super- ficial arcuate fibres). Pons [Varolii]. (a) Basilar groove (sulcus basilaris), (b) Oblique bundle of pons (fasciculus obliquus [pontis]). (c) Brachium ("arm") of pons (brachium pontis) (0. T. middle cere- bellar peduncle). Sulcus hypothalamicus [Monroi] Corpus fornicis \ Foramen interventriculare [Monroi] \ Septum pellucidum , ' Lamina rostralis Rostrum corporis callosi Genu corporis callosi Gyrus subcallo-l sus [Pedunculuss corporis callosi] . Sulcus parolfac- torius posterior Commissura ante- rior [cerebri] - -JHi Sulcus parollac- tori us anterior ^-- Area parolfac- ...s—« toria [Brocae] Lamina terminalis --£_ 'f Recessus optic us -*^ Recessus inf undibuli „_-••* Chiasma opticum Infundibulum Hypo- \ lobus anterior physis | lobus posterior Recessus anterior fossae-' / / interpeduncularis / ,. ' / Corpus mammillare'' // Fossa interpeduncularis [Tarini] / Nervus oculomotorius-' / / Sulcus n. oculomotorii / Recessus posterior fossae interpeduncularis / , Decussatio brachii conjunrtivi « Pons [Varolii] (fibrae superficiales) Fasciculi longitudinal es [pyramidal es] Foramen caecum / Fasciculus longitudinalis medialis Medulla spinalis- FIG. 144. Truncus corporis callosi ; Massa intermedia Thalamus j Tela chorioidea ventriculi tertii Ventriculus tertius I Aditus ad aquaeductum cerebri Commissura posterior [cerebri] ' Recessus pinealis Commissura habenularum •• Recessus suprapinealis Corpus pineale ^ Lamina quadrigemina !k/ Aquaeductus cerebri [Sylvii] Splenium corporis callosi Nucleus n. trochlearis ^ ,Velum medullare anterius mf Lobulus centralis Mi.nticulus (Culmen) ^^^^.Lingula cerebelli ^•L Ventriculus quartus Fastigium . Monticulus (Declive) k . Laminae medullares Folium vermis XTuber yennia "x^ Pyramis [vermis] t -^ 'Corpus medullare Nodulus \ Uvula [vermis] Velum medullare posterius Median section of the brain-stem. Right half seen from the left. (Only a small part of the pallium is shown.) (After Spalteholz, Hand Atlas of Hum. Anat., Leipzig, 1903, p. 63G, Fig. 695.) Isthmus of Rhombencephalon (Isthmus rhombencephali). (a) Brachium conjunctivum ("connecting arm") of cerebellum (bra- chium conjunctivum [cerebelli]) (0. T. superior cerebellar pe- duncle). (b) Fillet or ribbon (lemniscus) . (ba) Lateral fillet (lemniscus lateralis). (bb) Medial fillet (lemniscus medialis) (0. T. ribbon of Reil). (be) Trigone of fillet (trigonum lemnisci). 328 LABORATORY MANUAL OF HUMAN ANATOMY (c) Anterior medullary velum (velum medullare anterius) (0. T. valve of Vieussens). (ca) Frenulum ("rein" or "check-rein") of anterior medullary velum (frenulum veli medullaris anterioris). Midbrain (Mesencephalon). (a) Peduncle of cerebrum (pedunculus cerebri) (0. T. crus cerebri). (aa) Aqueduct of cerebrum (aquaeductus cerebri [Sylvii]) (0. T. iter e tertio ad quartum ventriculum). (ab) Lateral sulcus (sulcus lateralis). (ac) Sulcus of oculomotor nerve (sulcus N. oculomotorii) . (&) Quadrigeminal bodies (corpora quadrigemina) (0. T. optic lobes). (ba) Quadrigeminal layer (lamina quadrigemina). (bb) Superior hillock (colliculus superior) (0. T. anterior body or nates). (be) Inferior hillock (colliculus inferior) (0. T. posterior body or testis). (bd) Superior quadrigeminal brachium (brachium quadrigemi- num superius). (be) Inferior quadrigeminal brachium (brachium quadrigemi- num inferius). FIG. 145. Incisura cerebelli anterior Lobulus centralis Monticulus .Ala lobuli centralis Pars anterior \ lobuli quad- Pars posterior/ rangularis ., Sulci cerebelli Folium vermis- Incisura cerebelli— posterior — Lobulus semilu- naris superior Sulcus horizontalis cerebelli Lobulus semilunaris inferior The upper surface of the cerebellum. (After Toldt, Anat. Atlas, Wien. 1903, 3 AufL, p. 770, Fig. 1182.) Cerebellum. (a) Convolutions of cerebellum (gyri cerebelli). (b) Sulci of cerebellum (sulci cerebelli). (c) Cerebellar vallecula ("little valley") (vallecula cerebelli). (d) Anterior notch of cerebellum (incisura cerebelli anterior) (0. T. semilunar notch). (e) Posterior notch of cerebellum (incisura cerebelli posterior) (0. T. marsupial notch). (f) Horizontal sulcus of cerebellum (sulcus horizontalis cerebelli) (0. . T. great horizontal fissure). (g) Transverse fissure of cerebellum (fissura transversa cerebelli). (h) Vermis ("worm") (vermis). (ha) Lingua ("tongue") of cerebellum (lingua cerebelli). DISSECTION OF THE HEAD AND NECK 329 (haa) Vinculum of the lingua ("tongue-band") (vin- culum linguae cerebelli). (hb) Central lobule (lobulus centralis) (0. T. lobus centralis). (he) Monticulus (monticulus) (" little mountain"). (hca) Culmen (culmen) ("summit"). (hcb) Declive (declive) ("slope or descent"). FIG. 146. Incisura cerebelli anterior.^ Flocculus Uvula vermis, Tuber vermis Folium vermis - Lobulus biventer Lobulus semilunaris inferior Sulcus horizontals cerebelli Lobulus semi- lunaris superior Incisura cerebelli posterior" The lower surface of the cerebellum. (After Toldt, Anat. Atlas, Wien, 1903, 3 Aufl., p. 770, Fig. 1183.) (hd) Folium vermis (folium vermis) ("leaflet of worm") (0. T. folium cacuminis). (he) Tuber of vermis (tuber vermis) (0. T. tuber valvulus). (Tif) Pyramid of vermis (pyramis [vermis]). FIG. 147. Vellum medullare anterius Ala lobuli centralis. Vineulumlingulae cerebelli. Hemisphaerium cerebelli (facies superior) Flocculi seeuiKlarii Vermis superior "obulus centralis Lingula cerebelli Brachium conjunctivmn Corpus restiforme Brachium pontis Sulcus horizon- .talis cerebelli Flocculus Hemisphaeriurn cerebelli iiacics inferior) Vermis inferior Fissura transversa cerebelli ^ Velum medullare posterius "Nodulus vermis Uvula vermis Vallecula cerebelli ' The anterior surface of the cerebellum. (After Toldt, Anat. Atlas, Wien, 1903, 3 Aufl., p. 771, Fig. 1184.) (hg) Uvula of vermis (uvula [vermis]). (hh) Nodule (nodulus). (i) Hemisphere of cerebellum (hemisphaerium cerebelli). (ia) Superior surface (facies superior). 330 LABORATORY MANUAL OF HUMAN ANATOMY (iaa) Wing of central lobule (ala lobuli centralis). - (iab) Quadrangular lobule (lobulus quadrangularis) (0. T. quadrate lobule). (1) Anterior part (pars anterior), (2) Posterior part (pars posterior), (0. T. two anterior erescentic lobules). (iac) Superior semilmiar lobule (lobulus semilunaris superior) (0. T. posterior erescentic lobule). (ib) Inferior surface (fades inferior). (iba) Inferior semilunar lobule (lobulus semilunaris in- ferior) (0. T. postero-inferior lobule). (ibb) Slender lobule (lobulus gracilis). (ibc) Biventral lobule (lobulus biventer). (ibd) Tonsil of cerebellum (tonsilla cerebelli). (ibe) Flocculus (flocculus) ("wool-tuft-like body"). (1) Secondary flocculi (flocculi secundarii), in- constant. (2) Peduncle of flocculus (pedunculus -flocculi). (ibf) Nidus avis (nidus avis) ("bird's nest"). FIG. 148. Corpora quadrigemina Trigonum lemnisci Corpus geniculatum mediate,^ Pedunculus cerebri^ Brachium conjunctivum— <^j^' Brachium pontis,,_ Corpus restifonne .. Taenia ventriculi quarti Obex Tuberculum cuneatum- Tuberculum cinereum-- Clava- Funiculus cuneatus' Funiculus gracilis- Funiculus lateralis.. Commissura posterior cerebri ,Locus caeruleus Eminentia medialis Sulcus longitudlnalis fossae rhomboideae ,Fovea superior Colliculus facialis ^ Striae medullares . Area acustica --Tuberculum acusticum Fovea inferior (ala cinerea) Eminentia medialis (trigonum n. hypoglossi) Calamus scriptorius Fissura mediana posterior Sulcus intermedius posterior Sulcus lateralis posterior The dorsal surface of the medulla oblongata and midbrain and the floor of the fourth ventricle The lum has been removed. (After Toldt, Anat. Atlas, Wien, 1903, 3 Aufl., p. 768, Fig. 1178.) Fourth Ventricle (Ventriculus quartus). (a) Rhomboid fossa (fossa rhomboidea). (aa) Inferior part (pars inferior fossae rhomboideae [calamus scriptorius]). DISSECTION OF THE HEAD AND NECK 331 (ab) Intermediate part (pars intermedia fossae rhomb oideae) . (aba) Lateral recess (recessus lateralis fossae rhom- boideae). (ac) Superior part (pars superior fossae rhomb oideae) . (ad) Limiting groove (sulcus limitans [fossae rhomb oideae]) . (ada) Inferior pit (fovea inferior). (adb) Superior pit (fovea superior). (b) Trigone of hypoglossal nerve (trigonum N. hypoglossi). (c) Medullary striae (striae medullares) (0. T. striae acusticae). (d) Medial eminence (eminentia medialis) (0. T. eminentia teres). (e) Facial hillock (colliculus facialis). (f) Ash-like wing (ala cinerea) (0. T. trigonum vagi). (g) Acoustic area (area acustica) (0. T. trigonum acustici). (h) Locus caeruleus (locus caeruleus) ("blue place"). (i) Roof of fourth ventricle (tegmen ventriculi quarti). (ia) Posterior medullary velum (velum medullare posterius). (ib) Junction of epithelial part of roof with compact nerve sub- stance (taenia ventriculi quarti). (iba) Obex (pbex) ("bar"). (ic) Epithelial chorioid layer (lamina chorioidea epithelialis) . (ica) Median aperture (apertura mediana ventriculi quarti [foramen Magendii]). (icb) Lateral aperture (apertura lateralis ventriculi quarti). (id) Fastigium (fastigium) (" summit of roof "). External Morphology of Forebrain (Prosencephalon). Cut cautiously through the remaining cerebral peduncle and place the rhombencephalon and the mesencephalon in preserving fluid for further study later. In the prosencephalon distinguish the following parts : Forebrain (prosencephalon). Interbrain ( diencephalon) . Thalamic brain (thalamencephalon). Mammillary part of hypothalanms (pars mammillaris hypothalami). End-brain (telencephalon) . Hemisphere ( hemisphaerium ) . Optic part of hypothalamus (pars optica hypothalami). Make three drawings of the half of the prosencephalon before you— (a) Of medial surface (fades medialis cerebri). (Fig. 151.) (b) Of convex surface (fades convexa cerebri). (Fig. 149.) (c) Of base (basis cerebri). (Fig. 150.) Take up systematically the study of the external morphology as follows : 332 LABORATORY MANUAL OF HUMAN ANATOMY End-brain (Telencephalon). Note that it consists of the optic part of the hypothalamus (pars optica hypothalami) and the hemisphere (hemisphaer- ium). Hemisphere (Hemisphaerium). This includes the brain-mantle (pallium), the olfactory brain (rhinencephalon) , and the striate body (corpus striatum). The fissura longitudinalis cerebri was examined before the hemi- spheres were separated. Locate now the transverse fissure of the cerebrum (fissura transversa cerebri). FIG. 149. Fissura parieto- occipitalis Gyrus frontal is \ inferior Pars orbitalis Pars triangularis Pars opercularis '.! Operculum The left cerebral hemisphere. Lateral aspect. (After Toldt, Anat. Atlas, Wien, 1903, 3Aufl., p. 777, Fig. 1194.) Brain-mantle (Pallium). Note its subdivision by fissures (fissurae cerebri) and grooves (sulci cerebri) into convolutions (gyri cerebri). What is the fference arbitrarily made between a " fissure " and a " sul- cus"? Besides the main gyri, there are others in the depth (gyri profundi) and small gyri connecting adjacent gyri, the o-called gyri transitivi (0. T. annectent gyri). On the basis cerebri note the petrosal impression (impressio petrosa) due to the petrous portion of the temporal bone. The student should begin his study of the topography of the pallium with a careful examination of the lateral fissure of the DISSECTION OF THE HEAD AND NECK 333 cerebrum (fissura cerebri lateralis [Sylvii]), ordinarily known as the " fissure of Sylvius. " Besides its main trunk (truncus), observe — (a) Posterior ramus (ramus posterior). (b) Ascending anterior ramus (ramus anterior ascendens). (c) Horizontal anterior ramus (ramus anterior horizontalis} . FIG. 150. Fissura longitudinalis cerebri, Polus frontalis \ Sulcus olfactorius Sulci orbitales Bulbus olfactorius ,' _ Tractus olfactorius Polus temporalis Trigonum.^ olfactorium Chiasma opticum. 4££-.- — 7*-- — Fissura col- lateralis Sulcus tem^ ralis inferior Isthmus gyri fornicati'' Striae olfactoriae, medialis, intermedia, lateralis Substantia perforate anterior Limen insulae Fissura cerebri —lateralis (Sylvii) Nucleus amygdalae Pedunculus cerebri (Basis pedunculi) -Substantia per- forata posterior Substantia nigra Tegmentum Aquseductus cerebri (Sylvii) Lamina quadrigemina Gyrus fornicatus Polus occipitalis Splenium corporis callosi Fissura longitudinalis cerebri Basal surface of the cerebrum. (After Toldt, Anat. Atlas, Wien, 1903, 3 Aufl., p. 775, Fig. 1191.) Lobes of Cerebrum (Lobi cerebri) and their Boundaries. The pallium has been subdivided arbitrarily into five lobes (1) Frontal lobe (lobus frontalis). (2) Parietal lobe (lobus parietalis). (3) Temporal lobe (lobus temporalis). (4) Occipital lobe (lobus occipitalis). (5) Island of Reil (insula). 334 LABORATORY MANUAL OF HUMAN ANATOMY These five lobes are bounded by six fissures : (1) Fissure of Sylvius (fissura cerebri lateralis [Sylvii]). (2) Central sulcus of Rolando (sulcus centralis [Rolandi]) (0. T. fissure of Rolando). (3) Sulcus of cingulum (sulcus cinguli) (0. T. callosomarginal sulcus). (4) Parieto-occipital fissure (fissura parietooccipitalis) . (5) Collateral fissure (fissura collateralis}. (6) Circular sulcus of Reil (sulcus circularis [Reili]) (0. T. limiting sulcus of Reil). Frontal Lobe (Lobus frontalis). Find its posterior boundary on the convex surface by locating the sulcus centralis [Rolandi] ; the latter is always between the two parallel, obliquely placed, central gyri. What is the infe- rior boundary of the frontal lobe on the convex surface? How is it bounded on the medial surface of the hemisphere! In the frontal lobe study the following : (a) Frontal pole (polus frontalis). (b) Anterior central gyrus (gyrus centralis anterior}. (c) Precentral sulcus (sulcus praecentralis) . (d) Superior frontal gyrus (gyrus frontalis superior). (e) Superior frontal sulcus (sulcus frontalis superior). (f) Middle frontal gyrus (gyrus frontalis medius). (fa) Superior part (pars superior). (fb) Inferior part (pars inferior). (g) Inferior frontal sulcus (sulcus frontalis inferior), (h) Inferior frontal gyrus (gyrus frontalis inferior). (ha) Opercular part (pars opercularis) (on the left side this con- stitutes the celebrated Broca's convolution, concerned in the function of speech). (hb) Triangular part (pars triangularis). (he) Orbital part (pars orbitalis). (i) Straight gyrus (gyrus rectus). (j) Olfactory sulcus (sulcus olfactorius) . (k) Orbital gyri (gyri orbitales). (I) Orbital sulci (sulci orbitales). Parietal Lobe (Lobus parietalis). How is it bounded— (a) On the convex surface? (b) On the medial surface? Examine on the convex surface — (a) Posterior central gyrus (gyrus centralis posterior) (0. T. ascending parietal convolution). DISSECTION OF THE HEAD AND NECK 335 (b) Interparietal sulcus (sulcus inter parietalis) (0. T. intraparietal sulcus of Turner). Note the sulcus paroccipitalis of Wilder, (c) Superior parietal lobule (lobulus parietalis superior). (d) Inferior parietal lobule (lobulus parietalis inferior). (da) Supramarginal gyrus (gyrus supramarginalis) around end of fissure of Sylvius. (db) Angular gyrus (gyrus angularis), around end of sulcus tem- poralis superior. The portion of the parietal lobe on the medial surface of the hemisphere will be studied later. Occipital Lobe (Lobus occipitalis). How is it bounded— (a) On the convex surface? (b) On the medial surface? On the convex surface, examine— (a) Transverse occipital sulcus (sulcus occipitalis transversus). (b) Superior occipital gyri (gyri occipitales superiores). (c) Superior occipital sulci (sulci occipitales superiores}. (d) Lateral occipital gyri (gyri occipitales laterales). (e) Lateral occipital sulci (sulci occipitales laterales). Locate the occipital pole (polus occipitalis). The medial surface of the occipital lobe will be studied later. Temporal Lobe (Lobus temporalis). What are its boundaries! Observe the temporal pole (polus temporalis). Examine the following: (a) Transverse temporal sulci (sulci temporales transversi). (b) Transverse temporal gyri (gyri temporaleb transversi). (c) Superior temporal gyrus (gyrus temporalis superior) (0. T. first tem- poral gyrus). (d) Superior temporal sulcus (sulcus temporalis superior) (0. T. parallel sulcus, or first temporal sulcus). (e) Middle temporal gyrus (gyrus temporalis medius) (0. T. second tem- poral gyrus). (/) Middle temporal sulcus (sulcus temporalis medius) (0. T. second temporal sulcus). (g) Inferior temporal gyrus (gyrus temporalis inferior) (0. T. third tem- poral gyrus). (h) Inferior temporal sulcus (sulcus temporalis inferior) (0. T. occipito- temporal sulcus). (i) Fusiform gyrus (gyrus fusiformis) (0. T. occipitotemporal convo- lution). (j) Lingual gyrus (gyrus lingualis). In some English books this is re- garded as a part of the occipital rather than of the temporal lobe. 336 LABORATORY MANUAL OF HUMAN ANATOMY Medial Surface of Hemisphere (Facies medialis hemisphaerii). Here study— (a) Sulcus of corpus callosum (sulcus corporis callosi) (0. T. callosal sulcus). , (b) Fissure of hippocampus (fissura hippocampi) (0. T. dentate fissure, or fissura dentata) (between gyrus hippocampi and fascia den- tata). (c) Fornicate gyrus (gyrus fornicatus) (0. T. limbic or falciform lobe). (ca) Gyrus of cingulum (gyrus cinguli) (0. T. callosal convolu- tion, or gyrus fornicatus). (cb) Gyrus of hippocampus (gyrus hippocampi] (0. T. hippo- campal convolution). (cba) Hook of gyrus hippocampi (uncus gyri hippocampi] (0. T. uncinate gyrus). (ebb) White reticular substance of Arnold (substantia reticularis alba [Arnoldi] ) . (cc) Isthmus of fornicate gyrus (isthmus gyri fornicati). FIG. 151. Sulcus cinguli (pars marginalis) Sulcus subparietalis Fissura parieto- occipitalis Sulcus cinguli (pars subfrontalis) Sulcus corporis collosi calcarina Genu corporis callosi Rostrum corporis callosi \ \ Sulcus parolfactorius anterior \ Area parolfactoria (Brocse) » Sulcus parolfactorius posterior Gyrus subcallosus (Pedunculus corporis callosi) The left cerebral hemisphere. Medial aspect. (After Toldt, Anat. Atlas, Wien, 1903, 3 Aufl., p. 777, Fig. 1195) (d) Sulcus of cingulum (sulcus cinguli) (0. T. callosomarginal fissure). (da) Subf rental part (pars subfrontalis). (db) Marginal part (pars marginalis). (e) Subparietal sulcus (sulcus subparietalis). (f) Paracentral lobule (lobulus paracentralis) . This belongs to the frontal lobe. (g) Precuneus (praecuneus) . This belongs to the parietal lobe. DISSECTION OF THE HEAD AND NECK 337 (h) Parieto-occipital fissure (ftssura parietooccipitalis) . (i) Cuneus (cuneus) ("wedge"). This belongs to the occipital lobe. (j) Calcarine fissure (ftssura calcarina). Island (Insula) (O. T. Island of Reil, or Central Lobe). Pull the lips of the Sylvian fissure apart and examine the island. If possible, study the island on a fresh brain or on one prepared especially to show the island. How is it bounded! Examine carefully the overhanging operculum, and note that it is subdivisible into a frontal part (pars frontalis), a parietal part (pars parietalis), and a temporal part (pars temporalis). In the island study— (a) Sulci of island (sulci insulae). (b) Gyri of island (gyri insulae). (ba) Long gyrus of island (gyrus longus insulae). (bb) Short gyri of island (gyri breves insulae). Olfactory Brain (Rhinencephalon). (Vide Fig. 151.) Examine— (a) Anterior parolfactory sulcus (sulcus parolfactorius anterior). (b) Anterior part of rhinencephalon (pars anterior [rhinencephali]). (ba) Olfactory lobe (lobus olfactorius) . (baa) Olfactory bulb (bulbus olfactorius). (bab) Olfactory tract (tractus olfactorius) (incorrectly sometimes designated "olfactory nerve"). (bac) Olfactory trigone (trigonum olfactorium) . (bad) Medial stria (stria medialis). (bae) Intermediate stria (stria intermedia). (bb) Parolfactory area of Broca (area parolfactoria [Brocae]). (c) Posterior parolfactory sulcus (sulcus parolfactorius posterior). (d) Posterior part of rhinencephalon (pars posterior [rhinencephali]). (da) Subcallosal gyrus (gyrus subcallosus [pedunculus corporis callosi] ) . (daa) Anterior perforated substance (substantia perforata anterior). (db) Lateral olfactory stria (stria olfactoria lateralis). (dc) Threshold of island (limen insulae). Note that, in the broader sense, the gyrus fornicatus, fimbria and fascia dentata hippocampi, fornix, and corpora mammilla- ria are often classed as belonging to the rhinencephalon. In the fissura hippocampi note the fimbria hippocampi and the fascia dentata hippocampi (O. T. gyrus dentatus), lying side by side. The handle of the scalpel shoved deeply into the brain just above the fimbria would enter the inferior cornu of the lateral ventricle. 22 338 LABORATORY MANUAL OF HUMAN ANATOMY Hypothalamus (O. T. Subthalamic Region). Note that it is subdivisible into— (a) Mammillary part of hypothalamus (pars mammillaris hypothalami). This belongs to the diencephalon and includes — (aa) Mammillary body (corpus mammillare) on each side. (b) Optic part of hypothalamus (pars optica hypothalami). This belongs to the telencephalon and includes — (ba) Tuber cinereum (tuber cinereum) (" ash-like tuber" ). (bb) Infundibulum (infundibulum) ("funnel"). (be) Hypophysis (0. T. pituitary body). Cut through this in the median sagittal plane and note — (bca) Anterior lobe (lobus anterior), from the hypoblast. (bcb) Posterior lobe (lobus posterior), from the epiblast. (bd) Optic tract (tractus opticus). (bda) Medial root (radix medialis). .(bdb) Lateral root (radix lateralis). (be) Optic chiasm (chiasma opticum). (bf) Terminal lamina (lamina terminalis). Corpus Callosum (Great Transverse Commissure of Cerebrum). With a sharp, thin, broad brain-knife, the upper part of the right hemisphere should be sliced off at the level of the sulcus cinguli. The cortical substance (substantia corticalis) and semi- oval centre (centrum semiovale) of the hemisphere are thus beautifully displayed. Cut transversely through the middle of the gyrus cinguli; insinuate the fingers cautiously beneath it and tear it away lateralward, observing how the fibres of the corpus callosum enter the hemisphere. These fibres constitute the radiation of the corpus callosum (radiatio corporis callosi). This radiation is subdivisible into a frontal part (pars front alls] (0. T. forceps minor), a parietal part (pars parietalis), a tem- poral part (pars temporalis), an occipital part (pars occipi- talis) (0. T. forceps major), and the " tapestry" (tapetum), the layer of fibres coming from the truncus corporis callosi and curving lateralward and downward over the inferior and poste- rior horns of the lateral ventricle. In the gyrus cinguli, just torn away, note on the deep surface a very definite bundle of sagittally directed arcuate fibres, easily lifted out of the bed in which it lies. This is the cingulum or "girdle," an association bundle pertaining to the rhinencephalon. (See full description in Barker's Nervous System, p. 1061.) Examine— (a) Splenium ("bandage") of corpus callosum (splenium corporis cal- losi). (b) Trunk of corpus callosum (truncus corporis callosi) (0. T. body). (c) Knee of corpus callosum (genu corporis callosi). DISSECTION OF THE HEAD AND NECK 339 (d) Beak of corpus callosum (rostrum corporis callosi). (da) Rostral lamina (lamina rostralis). (e) Transverse striae (striae transversae) . (f) Medial longitudinal stria (stria longitudinalis medialis). (g) Lateral longitudinal stria (stria longitudinalis lateralis). (h) Fasciola cinerea (fasciola cinerea) ("ash-like little bandage"). Lateral Ventricle (Ventriculus lateralis). Make a sagittal incision through corpus callosum one centi- metre from sagittal median plane; the part of the corpus cal- losum lateral from the incision is to be reflected lateral ward and removed; leave the part of the corpus callosum medial from the incision in place. Note the relation of the splenium corporis FIG. 152. Cornu anterius Foramen interventriculare [Monroi] Ventriculus tertius ..Cornu inferius Aquaeductus cerebri [SylviiJ Ventriculus quartus .Cornu poster! us Cast of the ventricles. (After Welcker.) (From Poirier et Charpy, Traite d'Anat. hum., Paris, 1901, 2ed., t. iii., 1, p. 365, Fig. 260.) callosi to the pars occipitalis of the radiatio corporis callosi, or forceps major; leave the latter in place. The central part and anterior cornu of the lateral ventricle are now exposed. Make a cut backward and lateralward through the white matter which forms the roof of the posterior horn and excise enough of this roof to permit of thorough inspection of the cavity. To open the inferior horn, place the tip of the knife in the central part of the ventricle at the entrance to the inferior horn and make a cut downward and forward through the outer part of the temporal lobe towards the polus temporalis, following the course of the inferior horn, which runs nearly parallel to the sulcus temporalis superior. Now remove the part of the 340 LABORATORY MANUAL OF HUMAN ANATOMY temporal lobe above this incision, including the pars temporalis of the operculum ; take care not to injure the island. Observe the general form, and study the walls, of the various subdivisions of the lateral ventricle ; compare your observations with atlases, models, and text-book descriptions. FIG. 153. Genu corporis callosi Septum pellucidum Cornu anterius ventriculi lateralis Columna fornicis v Commissura anterior^ (cerebri) Polus temporalis - Nucleus amygdalae Digitationes hippocampi Uncus _ Cornu inferius ven- triculi lateralis Ventriculus tertius Hippocampus - Fimbria hippocampi Fascia dentata hippocampi Radiatio corporis callosi (pars temporalis) Calcar avis Cornu posterius ventriculi lateralis Cerebellum (vermis superior) atum (caput) Kecessus triangularis Tuberculum anterius < thalami Taenia chorioidea Massa intermedia tertii Stria medullaris thalami Commissura habenularum .Trigonum habenulae ~r~-™f - Hippocampus Habenula Corpus pineale Trigonum collaterale Eminentia collateralis Tapetum Corpora quadrigemina The ventricles of the brain shown completely opened from above. The upper part of the cerebral hemispheres, the corpus callosum, the fornix, and the tela chorioidea have been removed, and the corpora quadrigemina, corpus pineale, and vermis superior laid bare. (After Toldt, Anat. Atlas, Wien, 1903, 3 Aufl., p. 782, Fig. 1200.) (a) Head of caudate nucleus (caput nuclei caudati). (b) Anterior horn (cornu anterius). (c) Posterior horn (cornu posterius). (d) Inferior horn (cornu inferius) (0. T. descending horn). In the anterior horn study— (a) Head of caudate nucleus (caput nuclei caudati). In the central part of the ventricle study — DISSECTION OF THE HEAD AND NECK 341 (a) (6) (c) (d) (e) (9) (h) (*) Caudate nucleus (nucleus caudatus). Terminal stria (stria terminalis) (0. T. taenia semicireularis). Terminal vein (vena terminalis) (0. T. vein of the corpus striatum). Lamina affixa (lamina affixa) ("fastened layer"). (The embryology of the part must be studied, in order to under- stand the origin of this structure.) Chorioid plexus of lateral ventricle (plexus chorioideus ventriculi lat- eralis ) . Epithelial chorioid layer (lamina chorioidea epithelialis). Chorioid taenia (taenia chorioidea). Thalamus (thalamus) (showing through). Taenia of fornix (taenia fornicis) (0. T. sharp edge of fornix). FIG. 154. Transverse section through the tela chorioidea, ventriculi tertii, and adjacent parts. II, lateral ventricle ; III, third ventricle ; Cc, corpus callosum ; F, fornix ; Th, thalamus ; St. TO, stria medullaris ; St. t, stria terminalis ; V. t, vena terminalis ; L, lamina affixa ; 1, taenia thalami ; 2 , taenia chorioidea ; 3, taenia fornicis. The figure shows the continuity of the taeniae and the epithelial layer of the plexus chorioidea. (After His, Die Anat. Nomenclatur, Leipzig, 1895, p. 166, Fig. 21.) In the posterior horn of the ventricle study— (a) Roof and lateral wall formed by tapetum. (b) Two ridges on medial wall. (ba) Upper ridge = bulb of posterior horn (bulbus cornu poste- rioris), due to pars occipitalis of radiatio corporis callosi, the so-called " forceps major/' hooking around the fissura parieto-occipitalis. (feb) Lower ridge = calcar avis (calcar avis) (" cock's spur") (0. T. hippocampus minor), due to fissura calcarina. Before studying the inferior horn of the ventricle in detail, insert the fingers cautiously beneath the pars frontalis and pars parietalis of the operculum of the island, and tear away the cortex. This exposes the island thoroughly, and its relations to the lateral ventricle can be examined. In the inferior horn of the ventricle study— (a) Its narrow inferior wall. (aa) Collateral eminence (eminentia collateralis) , corresponding to the fissura collateralis ; it is sometimes absent. 342 LABORATORY MANUAL OF HUMAN ANATOMY (aaa) Collateral trigone (trigonum collaterale) (0. T. trigonum ventriculi). (b) Its lateral and superior walls. (ba) Tapetum. (bb) Lowermost end of striate body (corpus striatum). (be) Swelling due to amygdaloid nucleus (nucleus amygdalae). (bd) Terminal stria (stria terminalis). (be) Tail of caudate nucleus (cauda nuclei caudati). Section through the base of the brain and the hippocampus lying beneath it. Plexus chorioideus made ampler than the actual. . (After L. Edinger, Nervose Centralorgane, V. Aufl., Leipzig, 1896, S. 225. (c) Its medial wall. (ca) Hippocampus (hippocampus) ("sea-horse") (0. T. hippo- campus major, cornu Ammonis, or Ammon's horn). It corresponds to the fissura hippocampi of the facies medialis hemisphaerii. (caa) Digitations of the hippocampus (digitationes hip- pocampi) (0. T. pes hippocampi). DISSECTION OF THE HEAD AND NECK 343 (cb) Chorioid plexus (plexus chorioideus ventriculi lateralis). The fimbria hippocampi and fascia dentata hippocampi have already been examined. The edge of the fimbria after tearing away the .chorioid plexus is called the taenia fim- briae. The student should next remove the remains of the right temporal and occipital lobes ; cut through (a) the fimbria hippo- campi, where it passes into the crus fornicis, and (b) the occipi- tal part of the radiation of the corpus callosum (0. T. forceps major). Next make an incision from the anterior end of the cornu inferius forward, above the level of the uncus, through the polus temporalis. Now separate the lobus temporalis, with the gyrus hippocampi medial to it, from the rest of the hemisphere, the separation taking place along the line of the inferior part of the fissura transversa cerebri. Cut away enough of the lateral edge of the remaining medial part of the corpus callosum to permit of a good view of the septum pellucidum and the f ornix, lying beneath it. Having noted their relations, cut across the remains of corpus callosum behind the genu, gently raise the truncus corporis callosi, and dissect backward, freeing it from the septum pellucidum and, further back, from the fornix. Septum pellucidum. (a) Layer of septum pellucidum (lamina septi pellucidi). (b) Cavity of septum pellucidum (cavum septi pellucidi) (0. T. fifth ventricle). Fornix. (a) Body of fornix (corpus fornicis). (aa) Taenia of fornix (taenia fornicis). (b) Crus of fornix (crus fornicis) (0. T. posterior pillar of fornix). (c) Column of fornix (columna fornicis) (0. T. anterior pillar of fornix). (ca) Free part (pars libera columnae fornicis). (cb) Covered part (pars tecta columnae fornicis). Next cut transversely through the corpus fornicis at its middle and gently reflect the two ends forward and backward respectively. Running medialward from the crus fornicis, infe- rior to the corpus callosum, towards the crus fornicis of the opposite side, observe the commissure of the hippocampus (commissura hippocampi) (0. T. lyra or lyre of David). The space between the commissura hippocampi and the inferior sur- face of the corpus callosum has been called " Verga's ventricle. " One-half of the so-called chorioid tela of the third ventricle (tela chorioidea ventriculi tertii) (0. T. velum interpositum) is now 344 LABORATORY MANUAL OF HUMAN ANATOMY exposed; note how it is formed by the pia mater encephali coming in through the fissura transversa cerebri. In connection with it, study— (a) Upper lamella, next to inferior surface of corpus callosum and fornix. (b) Lower lamella, over the surface of the thalamus. (c) Between (a) and (b) some loose connective tissue, a continuation of the subarachnoideal connective tissue of the cisterna venae cerebri magnae. In this study — FIG. 156. Cq* Cq Ccq Gcb Co II' Spa A portion of the right cerebral hemisphere resting on the polus frontalis, to illustrate the basis cerebri. Sea, brachium quadrigeminum superius ; Bcp, brachium quadrigeminum inferius ; Ccb, pedunculus cerebri ; Cgl, corpus geniculatum laterale ; Cgm, corpus geniculatum mediale ; Ccq, brachium conjunc- tivum ; Co, chiasma opticum ; Cq1, colliculus inferior ; Cqi, colliculus superior ; L, lemniscus ; Pv, pul- vinar of thalamus ; Spa, substantia perforata anterior ; St, stria terminalis ; II', tractus opticus. The radix medialis and the radix lateralis are well illustrated ; f, cut surface of tip of temporal lobe which has been removed. (After J. Henle, Handbuch der Nervenlehre des Menschen, II. Aufl., Braunsch.. 1879, S. 155, Fig. 80.) (ca) The two internal veins of the cerebrum (venae cerebri inter- nae) (0. T. veins of Galen), and their tribu- taries— (caa) Vein of septum pellucidum (V. septi pellucidi). (cab) Terminal vein (V. terminalis) (0. T. vein of the corpus striatum). (cac) Chorioid vein (V. chorioidea). The venae cerebri internae unite to form the DISSECTION OF THE HEAD AND NECK 345 large vein of the cerebrum (vena magna cerebri [Galeni]), which in turn opens into the straight sinus (sinus rectus). (d) Chorioid plexus of lateral ventricle (plexus chorioideus ventriculi lat- eralis ) . Pul Po Isthmus rhombencephali seen in profile. BIT, tractus opticus ; BrQa, brachiura quadrigeminum superius ; BrQp, brachium quadrigeminum inferius ; Cge, corpus geniculatum laterale ; Cgi, corpus geniculatum mediale ; Chll, chlasma opticum ; Crst, corpus restiforme ; Fla, funiculus lateralis of medulla oblongata ; Jaa, fibrae arcuatae externae ; Fob, fibrae superficiales pontis ; Cp, corpus pineale ; Nil, N. opticus ; Oi, oliva ; P, pedunculus cerebri ; Pern, brachium pontis; PCS, brachium conjunctivum; Po, pons Varoli ; Pul, pulvinar; Py, pyramis; Qa, colliculus superior; Qp, colliculus inferior; SI, trigonum lemnisci; Rm, lemniscus medialis; si, sulcus lateralis; Th, thalamus; Tpo, taenia pontis; Tpt, tractus peduncularis transversus. (After J. D6jerine, Anatomic des centres nerveux, t. i., Paris, 1895, p. 328, Fig. 192.) (da) Chorioid skein (glomus chorioideum) . Now cut through the V. terminalis at its junction with the V. cerebri interna, seize the apex of the right half of the tela chorioidea ventriculi tertii, and pull it with the chorioid plexuses backward, but be careful not to tear away the corpus pineale beneath it behind. Examine — (e) Chorioid plexus of third ventricle (plexus chorioideus ventriculi tertii) . 346 LABORATORY MANUAL OF HUMAN ANATOMY Thalamencephalon. This part of the diencephalon includes (1) the thalamus, (2) the metathalamus, and (3) the epithalamus. Thalamus (O. T. Optic Thalamus). The upper and medial surfaces of the thalamus may now be examined. Observe — ^a) Pulvinar (pulvinar) ("cushion"). (b) Anterior tubercle of the thalamus (tuberculum anterius thalami). (c) Medullary stria (stria medullaris) (0. T. stria fornicis or stria pine- alis). (d) Epithelial chorioid layer (lamina chorioidea epithelialis) . This covers the thalamus where it appears to be, but is not, in the lateral ventricle. Metathalamus. Behind and beneath the thalamus observe— (a) Medial geniculate body (corpus geniculatum mediale) (0. T. internal geniculate body). This has to do chiefly with the auditory conduc- tion path. (b) Lateral geniculate body (corpus geniculatum laterale) (0. T. external geniculate body). This has to do with the visual conduction path. Epithalamus. Here the student should study— (a) Pineal body (corpus pineale) (0. T. conarium, or epiphysis cerebri). (b) Pineal recess (recessus pinealis). (c) Suprapineal recess (recessus suprapinealis) . (d) Habenula (0. T. peduncle of the pineal body). (e) Commissure of the habenulae (commissura habenularum) . (f) Trigone of the habenula (trigonum habenulae). Third Ventricle (Ventriculus tertius). This has been cut in two in the median plane, and its roof, tela chorioidea ventriculi tertii, with the lamina chorioidea epi- thelialis, has been removed. The student should now study the following structures and openings : (a) Entrance to the aqueduct of the cerebrum (aditus ad aquaeductum cerebri). (b) Posterior commissure of the cerebrum (commissura posterior [cere- bri]) (above the aditus ad aquaeductus cerebri). (c) Interventricular foramen of Monro (foramen interventriculare [Mon- roi]). One on each side, connecting ventriculus tertius with ven- triculus lateralis. DISSECTION OF THE HEAD AND NECK 347 (d) Hypothalamic sulcus of Monro (sulcus hypothalamicus [Monroi]). Note the importance of this in connection with the embryology of the brain. Compare with the sulcus limitans in the floor of the fourth ventricle. (e) Intermediate mass (massa intermedia) (0. T. middle or soft or gray commissure). (/) Optic recess (recessus opticus). (Cf. W. His's models of developing brain.) (g) Recess of infundibulum (recessus infundibuli) . (h) Anterior commissure of cerebrum (commissura anterior [cerebri]). (i) Triangular recess (recessus triangularis) . SECTIONS THROUGH BRAIN (SECTIONES ENCEPHALI). Sections of Medulla Oblongata (Sectiones medullae oblongatae). Make three transverse sections through the medulla oblon- gata: (1) at the level of the decussation of the pyramids; (2) between the decussation of the pyramids and the olives; (3) FIG. 158. Fissura mediana posterior Nucleus fasciculi gracilis Nucleus fasciculi cuneati Nucleus tract-, spinal is N. tri gemini Formatio reticularis- Fasciculus gracilis [Golli] Fasciculus cuneatus [Burdachi] Secondary trigeminal path Tractus spinalis N. trigemini Fasciculus cere- bellospinalis Fila radicularia N. accessorii Gowers' tract and the tract to the lateral funiculus from Deiters' nucleus and from the red nucleus Fasciculus longitudinalis medialis Columna anterior Substantia grisea centralis Decussatio pyramid um Pyramis [medullae oblongatae] Transverse section of the brain-stem of an adult, through the decussation of the pyramids. Magnifica- ation : 6 : 1. (After Spalteholz, Hand Atlas of Hum. Anat., Leipzig, 1903, vol. iii., p. 656, Fig. 725.) through the middle of the olives. (Cf. Spalteholz, Fig. 723.) Examine first the unstained cross-sections and subsequently sec- tions, from the same levels, stained by Weigert's method.1 Use 1 The study is much simplified if sections through the brain-stem of a new- born babe are used; see Figs. 162-169. 348 LABORATORY MANUAL OF HUMAN ANATOMY a hand-lens or dissecting microscope, eating- Make drawings indi- (1) Median raphe (raphe). (2) Nuclear layer (stratum nuclear e}. (3) Nucleus of hypoglossal nerve (nucleus N. hypoglossi). (4) Ambiguous nucleus (nucleus ambiguus). (5) Nucleus of ala cinerea (nucleus alae cinereae). (6) Solitary tract (tractus solitarius) (0. T. respiratory bundle). (a) Nucleus of solitary tract (nucleus tractus solitarii). FIG. 159. Nucleus fasciculi gracilis Ganglion commissurale alae cinereae Nucleus fasciculi cuneati Substantia grisea centralis Nucleus tractus spinalis N. trigemini Formatio reticu - laris Fissura mediana posterior Fasciculus gracilis [Golli] Fasciculus cuneatus [Burdachi] Secondary trigeminal path ..Tractus spinalis " N. trigemini — Tuberculum cinereum . . Fasciculus cere- bellospinalis Fibrae arcuatae internae j Fissura mediana anterior Columna anterioT^^H& . i$^J \ Cowers' tract and the tract to the lateral funiculus from Deiters' nucleus and from the red nucleus Fila radicularia N. cervicalis I v \ Fasciculus longitudinalis medialis Pyramis [medullare oblongatae] Decussatio lemniscorum Transverse section through the brain-stem of an adult, between the decussation of the pyramids the olives. Magnification: 6:1. (Held.) (After Spalteholz, Hand Atlas of Hum. Anat., Leipzig, j.yuo, vol. ill., p. boo, .tig. 726.) (7) Spinal tract of trigeminal nerve (tractus spinalis N. trigemini) (0. T. ascending root of trigeminal nerve— a very bad name, for the fibres descend). (a) Nucleus of spinal tract of trigeminal nerve (nucleus tractus spinalis N. trigemini). (8) Nucleus of slender funiculus (nucleus funiculi gracilis) (0. T. nu- cleus of Goll's column). Nucleus of wedge-shaped funiculus (nucleus funiculi cuneati) (0. T. nucleus of Burdach's column). (10) Lateral nuclei (nuclei laterales). (11) Inferior olivary nucleus (nucleus olivaris inferior). (a) Hilus of olivary nucleus (hilus nuclei olivaris). (b) Medial accessory olivary nucleus (nucleus olivaris accessorius medialis). (9) DISSECTION OF THE HEAD AND NECK 349 FIG. 160. Area acustica Taenia ventriculi quarti Tractus solitarius *'» Nucleus N. vestibularis medialis [Schwalbe] Nucleus tractus solitarii \ \\\ Kadix dyscend..!.^ X. v.-stibularis \ \ U • Fila radicularia N. glossopharvngei Alacinerea.\ Nucleus alae cinereae ' Trigonum N. hypoglossi Sulcus medianus fossae ^ t rhomboideae Nucleus N. hy Fasciculus longitudinalis medialis Snbstantia reticularis grisea — (Nucleus lateralis inferior) Substantia reticularis alba — Fibrae cerebello-olivares ._. Fila radicularia - N. hypoglossi Stratum interolivare ^ lemnisci Raphe — Fibrae arcuatae externae (to the corpus restiforme) " Nucleus arcuatus Pyramis [medullae oblongatae] Nucleus tractus spinalis N. trigemini ^Corpus restiforme .Tractus spinal is N. trigemini Lateral areas of the for- matio reticularis la radicularia N. vagi .Nucleus ambiguus .Growers' tract and the tract to the '' lateral funiculus from Deiters' nucleus and from the red nucleus Nucleus olivaris accessories dorsal is "-.Fibrae arcuatae externae ^x-Hilus nuclei olivaris \ N. hypoglossus Nucleus olivaris inferior Nucleus olivaris accessorius medialis Transverse section of the brain-stem of an adult through the middle of the olive. Magnification : 4.5 : 1 (Held. ) (After Spalteholz, Hand Atlas of Hum. Anat., Leipzig, 1903, vol. iii., p. 657, Fig. 727.) FIG. 161. Nu.com. F.c.toEr. Transverse section through medulla oblongata of new-born child at level of decussatio lemnis- corum. (Series ii. section No. 50.) 1 C.c., canalis centralis ; Dec.l., decussatio lemniscorum ; F.a.i., fibrae arcuatae internae ; F.a.e., fibrae arcuatae externae ; .F.c., fasciculus cuneatus Burdachi ; F.c. to F.r., bundles from fasciculus cuneatus to formutio reticularis ; F.ds., fasciculus cerebellospinalis or direct cen-bellnr tract ; F.g., fasciculus gracilis Golli ; F.v.p., fasciculus ventralis proprius ; .\ti.<-»in., nucleus commissuralis ; Xit.f.c., nucleus funiculi cuneati et gracilis ; A>/./.> 3 2- ^ ? § e S-f ill I .? 11.^1^ 352 LABORATORY MANUAL OF HUMAN ANATOMY (c) Dorsal accessory olivary nucleus (nucleus olivaris accessorius dorsalis). (12) Arcuate nuclei (nuclei arcuati). (13) Internal arcuate fibres (fibrae arcuatae internae). (14) Gray reticular substance (substantia reticularis grisea). (15) White reticular substance (substantia reticularis alba). FIG. 165. NYttPIIS) Transverse section through the pons and cerebellum at the level of the principal motor nucleus of the trigeminal nerve. New-born babe. (Weigert-Pal, series ii. section No. 212.) Br.conj., brachium conjunctivum ; C.t., corpus trapezoideum ; F.l.m., fasciculus longitudinalis medialis ; F.Py., fasciculi pyramidales in the pars basilaris pontis ; L.m., lemniscus medialis ; X. V. (dec. ) , decussating part of root of N. trigeminus ; N. V. (motor), root of N. trigeminus ; N. V.(scrts), sensory root of N. trigeminus; N. V.I., root fibres of N. abducens ; Nu.m.m.n. V., nuclei motorii minores N. trigemini ; Nu.m.p.n. V., nucleus motorius princeps N. trigemini; Nu.o.s., nucleus olivaris superior and superior olivary complex ; R.d.n. V., radix descendens [mesencephalica] N. trigemini ; S.g., substantia gelatinosa. (From Barker, The Nerv. Syst., New York, 1899, p. 483, Fig. 313.) (16) Medial longitudinal fasciculus (fasciculus longitudinalis medialis) (0. T. posterior longitudinal bundle). (17) Interolivary layer of lemniscus (stratum interolivare lemnisci). (18) Decussation of lemniscus or fillet (decussatio lemniscorum) (0. T. sensory decussation of medulla oblongata). DISSECTION OF THE HEAD AND NECK 353 (19) Restiform body (corpus resti forme) (0. T. inferior cerebellar peduncle), (a) Fasciculi of restifonn body (fasciculi corporis restiformis). (20) Cerebello-olivary fibres (fibrae cerebelloolivares) . (21) Pyramidal fasciculi (fasciculi pyramidales) . (22) External arcuate fibres (fibrae arcuatae externae). Sections of Pons (Sectiones pontis). Make four sections through the pons. (See Spalteholz. Fig. 723.) FIG. 166. Transverse section through isthmus rhombencephali of new-born babe. (Weigert-Pal, series ii. section No. 268.) Sr.conj., brachium conjunctivum ; C.i., colliculus inferior; y, nucleus described by Westphal as probably concerned in the origin of the N. trochlearis ; F.l.m., fasciculus longitudinalis medialis ; F.Py., fasciculi longitudinales [pyramidales] ; L.I., lemniscus lateralis; L.m., lemniscus medialis; N.IV., decussatio nervorum trochlearium ; N.V., N. trigeminus ; yu.l.l., nucleus lemnisci lateralis; Nu.r.t. nucleus reticularis tegmenti pontis ; R.d. V., radix descendens [meseucephalica] nervi trigemini. (From Barker, The Nerv. Syst., New York, 1899, p. 484, Fig. 314.) (1) About at the junction of the pons and the medulla, passing through the level of entrance of N. acusticus. (2) At the level of the roots of N. facialis and N. abducens. (3) At the level of the roots of N. trigeminus. (4) Through the velum medullare anterius and the middle of the pons. Examine first the unstained cross-sections and subsequently sections, from the same levels, stained by Weigert's method. 23 354 LABORATORY MANUAL OF HUMAN ANATOMY Use a hand-lens or dissecting microscope. Make drawings indi- cating— In dorsal part of pons (pars dorsalis pontis). (1) Median raphe (raphe). (2) Nucleus of N. abducens (nucleus N. abducentis) (0. T. nucleus of sixth nerve). (3) Motor nuclei of trigeminal nerve (nuclei motorii N. trigemini}. (4) Descending or mesencephalic root of trigeminal nerve (radix mesencephalica N. trigemini). (5) Spinal tract of trigeminal nerve (tractus spinalis N, trigemini). (a) Nucleus of spinal tract of trigeminal nerve (nucleus tractus spinalis N. trigemini). (6) Nucleus of facial nerve (nucleus N'. facialis). (7) Root of facial nerve (radix N. facialis). (a) First part (pars prima). (b) [Internal] knee (genu [internum]). (c) Second part (pars secunda). (8) Nuclei of acoustic nerve (nuclei N. acustici) (0. T. auditory nucleus). (a) Nuclei of cochlear nerve (nuclei N. cochlearis). (aa) Ventral (nucleus N. cochlearis ventralis). (ab) Dorsal (nucleus N. cochlearis dorsalis [tubercu- lum acusticum] ) . (b) Nuclei of vestibular nerve (nuclei N. vestibularis) . (ba) Medial nucleus (nucleus N. vestibularis medialis). (bb) Lateral nucleus (nucleus N. vestibularis lateralis [Deitersi] ) . (be) Superior nucleus (nucleus N. vestibularis superior [Bechterewi] ) . (bd) Nucleus of descending root (nucleus N. vestibularis radicis descendentis) . (9) Superior olivary nucleus (nucleus olivaris superior). (10) Nucleus of lateral lemniscus (nucleus lemnisci lateralis). (11) Medial longitudinal fasciculus (fasciculus longitudinalis medialis) (0. T. posterior longitudinal bundle). (12) Reticular formation (formatio reticularis) . (13) Trapezoid body (corpus trapezoideum) . (14) Fillet or lemniscus (lemniscus). (a) Medial (sensory) fillet (lemniscus medialis [sensitivus] ) . (b) Lateral (acoustic) fillet (lemniscus lateralis [acusticus]) . In basilar part of pons (pars basilaris pontis). (1) Deep fibres of pons (fibrae profundae pontis). (2) Longitudinal pyramidal fasciculi (fasciculi longitudinales [pyrami- dales]). (3) Nuclei of pons (nuclei pontis). (4) Superficial fibres of pons (fibrae pontis superficiales) . Sections of Cerebellum (Sectiones cerebelli). Make a sagittal median section through the vermis. (Vide Fig. 144.) DISSECTION OF THE HEAD AND NECK 355 Study- (1) Medullary body (corpus medullare). (2) Medullary laminae (laminae medullares). (3) Arbor vitae (arbor vitae) ("tree of life"). (4) Cortical substance (substantia corticalis). (a) Inner, yellowish or reddish-brown, " granular" layer (stratum granulosum). (b) Outer gray layer (stratum cinereum). (c) Layer of Purkinje's cells between (a) and (b) (stratum gan- gliosum ) . Transverse section through brain of new-born babe. Level of colliculi inferiores of corpora quadrigemina. ( Weigert-Pal, series ii. section No. 290. ) Aq.cer., aquaeductus cerebri ; a, fibres running from lateral lemniscus toward dorsal border of brachium conjunctivum ; Br.Conj., brachium conjunctivum; C.c.L, commissure between the colliculi inferiores; Dec.Bech., ventral portion of brachium conjunctivum, which in reality forms a commissure between the superior nuclei of the vestibular nerves of the two sides; F.l.m., fasciculus longitudinalis medialis ; F.Py., fasciculi longitudinales pontis (pyramidales) ; L.I., lemniscus lateralis in large part terminating in the nucleus of the colliculus inferior ; L.m., lemniscus medialis; N.IV., N. trochlearis ; Nu.Coll.inf., nucleus colliculi inferioris ; Fu.c.s.(l), nucleus centralis superior, pars lateralis ; Nu.c.8.(m), nucleus centralis superior, pars medialis; R.d.n.V., radix descendens [mesencephalica] N. trigemini; St.gr.c., stratum griseum centrale. (From Barker, The Nerv. Syst., New York, 1899, p. 485, Fig. 315.) Make a frontal section through the left half of the cerebellum at about its middle (cf. Spalteholz, Fig. 743), and a horizontal section through the right half of the cerebellum in the general 356 LABORATORY MANUAL OF HUMAN ANATOMY direction of the brachium conjunctivum (cf. Spalteholz, Fig. 744). In these, study the following: (1) Dentate nucleus (nucleus dentatus). (a) Hilus of dentate nucleus (hilus nuclei dentati). (b) Capsule of nucleus dentatus (capsula nuclei dentati). (2) Nucleus of fastigium ("roof") (nucleus fastigii). (3) Nucleus fclobosus (nucleus globosus) (" spherical nucleus"). (4) Emboliform nucleus (nucleus emboliformis) (0. T. cork or plug). FIG. 168. Dpc.Br.Conj. Transverse section through mesencephalon of new-born babe. Level of colliculi superiores of corpora quadrigemina. (Weigert-Pal, series ii. section No. 338.) Aq.cer., aquaeductus cerebri ; Dec.Br.Conj., decussatio brachii conjunctivi ; D.t., decussatio tegmenti ventralis (ventrale Haubcnkreuzung of Forel) ; F.l.m,, fasciculus longitudinalis medialis ; F.Py., fasciculi pyramidales in the pars basilaris pontis; L.m., lemniscus medialis; N.IV., N. trochlearis; Nu.l.s., nucleus lateralis superior of Flechsig; Nu.n.IV., nucleus N. trochlearis; St.alb.p., stratum album pro- fundum; St.gr.c., stratum griseum centrale ; S.n., substantia nigra. (From Barker, The Nerv. Syst., New York, 1899, p. 486, Fig. 316.) Sections of Rhombencephalic Isthmus, Corpora Quadrigemina, and Cerebral Peduncle (Sectiones isthmi, corporum quadrigemi- norum, et pedunculi cerebri). Make two sections: (1) through the inferior colliculus at the level of the nucleus of the N. trochlearis; (2) through the level of the roots of the N. oculomotorius, nucleus ruber, superior colliculus, and lateral geniculate body. (Cf. Spalteholz, Fig. 723.) DISSECTION OF THE HEAD AND NECK 357 Study- In the isthmus rhombencephali. (1) Interpeduncular ganglion (ganglion inter peduncular e). (2) Nucleus of trochlear nerve (nucleus N. trochlearis). In the pedunculus cerebri. (A) Tegmentum. (1) Central gray layer (stratum griseum centrale). (2) Reticular formation (formatio reticularis) . (3) Medial longitudinal fasciculus (fasciculus longitudinalis medialis) (0. T. posterior longitudinal bundle). FIG. 169. Coll.sup. Aq.cer, St.gr.c, a Transverse section through mesencephalon, colliculi superiores of corpora quadrigemina and cerebral peduncle of new-born babe. (Weigert-Pal, series ii. section No. 384.) Aq.cer., aquaeductus cerebri; Coll.sup., colliculus superior; D.t., decussatio tegmenti dorsalis (fon- taineartige Haubenkrcuzung of Meynert); F.l.m., fasciculus longitudinalis medialis; F.Py., fasciculi pyramidales in the basis pedunculi ; F.r.(M), fasciculus retroflexus Meynerti ; L.m., lemniscus medialis ; Nu. F.l.m., nucleus fasciculi longitudinalis medialis or nucleus commissurae posterioris (oberer Octdomo- toriuskern of Darkschewitsch) ; Nu.n.III, nucleus N. oculomotorii ; Nu.r., nucleus ruber ; N.III, N. oculomotorius ; St.alb.p., stratum album profundum; St.gr.c., stratum griseum centrale ; S.n., substantia nigra ; a, region of Flechsig's Fussscfdeife ; /3, temporo-occipital tract to pons ; y, frontal tract from pallium to pons. (From Barker, The Nerv. Syst, New York, 1899, p. 487, Fig. 317.) (4) Descending root of trigeminal nerve (radix descendens N. trigemini). (5) Nucleus of descending root of trigeminal nerve (nucleus radicis descendentis N. trigemini = nuclei motorii mi- nor es N. trigemini}. (6) Nucleus of oculomotor nerve (nucleus N. oculomo.torii) (0. T. nucleus of III. nerve). (7) Nuclei of tegmentum (nuclei tegmenti). (a) Red nucleus (nucleus ruber). (8) Decussations of tegmenta (decussationes tegmentorum) . 358 LABORATORY MANUAL OF HUMAN ANATOMY (a) Decussation of brachium conjunctivum (decussatio brachii conjunctivi). (b) Dorsal decussation of tegmentum (decussatio teg- menti dorsalis) (German 0. T. fontaineartige Haubenkreuzung) . (c) Ventral decussation of tegmentum (decussatio teg- menti ventralis). (9) Lateral fillet (lemniscus later alls}. (10) Medial fillet (lemniscus medialis). (B) Base of peduncle (basis pedunculi) (0. T. "foot" of cerebral peduncle, or pes pedunculi). (1) Pyramidal path (fasciculi cerebrospinales) . (2) Temporal pontile path (fasciculus temporopontilis) (0. T. Turk's bundle). (3) Frontal pontile path (fasciculus frontopontilis) (0. T. Ar- nold's bundle). Between (A) and (B), study the substantia nigra (substantia nigra) (" black substance"). In the corpora quadrigemina. (1) Zonal layer (stratum zonale). (2) Gray layer of superior colliculus (stratum griseum colliculi supe- rioris). (3) Nucleus of inferior colliculus (nucleus colliculi inferioris). (4) Deep white layer (stratum album profundum). Sections through Prosencephalon (Sectiones diencephali et telen- cephali). Take the portion still remaining of the right cerebral hemi- sphere; with a broad, thin, sharp brain-knife, make horizontal slices, one-half or one centimetre thick, down as far as the level of the commissura anterior cerebri. Make a drawing of the surface of each slice. (Vide Fig. 177.) The left half of the brain, thus far preserved intact, should now be divided, at the choice of the instructor, either into vertical frontal or into obliquely frontal sections, the latter according to the method of Pitres.1 All the oblique sections pass in planes parallel to the course of the sulcus centralis Rolandi. Place the four fingers of the left hand in the sulcus centralis [Eolandi] , the hemisphere lying upon its medial surface with the polus occipitalis directed towards you. With the sharp, broad, thin brain-knife, make six sections from before backward, as indi- cated in the accompanying diagram. (Cf. Fig. 170.) 1 Pitres, Recherches sur les lesions du centre oval des hemispheres cerebraux, etudiees au point de vue des localisations cerebrales. Paris, 1877. DISSECTION OF THE HEAD AND NECK 359 (1) Prefrontal section, passing through the front of the lobus frontalis about live centimetres in front of the sulcus centralis and parallel to it. (2) Operculo frontal or pediculo frontal section, through the pars opercu- laris of the gyms frontalis inferior and the corresponding portions of the gyrus frontalis medius and gyrus frontalis superior ; in other words, through the " feet" of the frontal gyri. (3) Frontal section, through the middle of the gyrus centralis anterior. (4) First parietal section, through the middle of the gyrus centralis pos- terior. (5) Second parietal or pediculoparietal section, through the anterior ex- tremities ("feet") of the lobulus parietalis superior and lobulus parietalis inferior. (6) Occipital section, about one centimetre in front of the fissura parieto- occipitalis. FIG. 170. Operculofrontal Prefrontal section Frontal pj^ parietal Second parietal Occipital Prefrontal Operculofrontal Frontal / First parietal / Second parietal Pitres' method of sectioning the cerebral hemisphere.1 It will be advantageous to the student while studying anat- omy to become familiar with these obliquely frontal sections, as well as with the vertical frontal, for it is the former that are more often employed at the autopsy table of the pathological laboratories. The prefrontal section shows the cortex and white matter of the three frontal gyri, the orbital gyri, and the medial surface of the frontal lobe. The pediculo frontal section passes through the three frontal gyri, anterior end of island, orbital gyrus, corpus callosum, eaput nuclei caudati, ante- rior part of nucleus lentiformis, and lentieulostriate part of capsula interna. 1 The lines indicating the planes of the sections slope too much in this figure. 360 LABORATORY MANUAL OF HUMAN ANATOMY The frontal section passes through the gyrus centralis anterior, island, temporal gyri, corpus callosurn, cauda nuclei caudati, thalamus, middle piece of nucleus lentiformis, anterior part of lenticulo-optic part of capsula interna, capsula externa, and claustrum. The first parietal section passes through the gyrus centralis posterior, island, temporal gyri, corpus callosum, cauda nuclei caudati, posterior end of thalamus and of nucleus lentiformis, posterior end of lenticulo- optic part of capsula interna, capsula interna, capsula externa, and claustrum. The pediculo parietal section passes through the lobuli parietalis superior et inferior, temporal gyri, corpus callosum, most posterior part of thalamus, and cauda nuclei caudati. The occipital section passes through the cortex and white matter of the lobus occipitalis. In addition to the horizontal sections and frontal sections above mentioned, the student should study, if possible (perhaps from the anatomical museum), two other sections: (1) Section through the brain in a plane passing parallel to the course of the brachia conjunctiva and through them. (Cf. Spalteholz, Fig. 744.) (2) Section through the brain in a plane parallel to the course of the cerebral peduncles and through them. (Cf. Spalteholz, Fig. 745.) FIG. 171. Taenia semicircularis^ Nucleus lateralis thalami. Lamina medullaris medialis^ Nucleus medialis thalami. Ventriculus tertius- .. „ -Lamina medullaris lateralis Forel's Feld H— Nucleus ruber /*V ' '" 'JtfF$&%&*3xr N >• ;?;^>«^^^PN ^Nucleus hypothalamicus (corpus Luysi) ,"***^3SX \x BAThof Forel N. oculomotorius Substantia nigra Frontal section through the human brain-stem. BA Th, large bundle of fibres which, coming from the nucleus ruber and its capsule, runs upward, lateralward, and dorsalward to the ventral part of the thalamus to the reticular layer, to the lamina medullaris lateralis, etc., where the fibres become so interwoven with others that they cannot be fol- lowed farther; Ford's Feld H, dorsal white matter of regio subthalamica. (After A. Forel, Arch. f. Psychiat., Berl., Bd. vii., 1877, Taf. vii., Fig. 10.) Drawings should be made of all these sections, and the fol- lowing structures designated when met : Sections of Hypothalamus (Sectiones hypothalami). (1) Hypothalamic nucleus, or Luys's body (nucleus hypothalamicus [cor- pus Luysi}} (0. T. subthalamic nucleus). (2) Gray part of hypothalamus (pars grisea hypothalami). DISSECTION OF THE HEAD AND NECK 361 (3) Superior commissure of Meaner! (commissura superior [Meynerti]). (4) Inferior commissure of v. Gudden (commissura inferior [Guddeni]). (5) Nuclei of mammillary body (nuclei corporis mammillaris) . FIG. 172. Lamina medullaris media Capsula interna___^;c Nucleus lentifonnis. Lamina medullaris medialis / Nucleus medialis thalami (6) / / (centre median) Nucleus medialis thalami (a) Taenia thalami '~ 1- Lamina medullaris thalami Nucleus ruber •'«!--- Fasciculus retroflexus [M^nerti] Fasciculus pedunculomammillaris pars tegmentalis Nucleus hypothalamicus (corpus Luysi) Ventriculus lateralis (cornu inferius) / ,' Nucleus ventralis thalami (a) •' / Nucleus ventralis thalami (6) ! Basis pedunculi Frontal section through a normal human brain at the level of the lower end of the nucleus hypothalamicus. a, dorsal white matter of nucleus ruber ; /3, ventral white matter of nucleus ruber ; y, lateral white matter of nucleus ruber. (After C. von Monakow, Arch. f. Psychiat., Berl., Bd. xxvii., 1895, Taf. iii., Fig. 20.) (6) Thalamomammillary fasciculus (fasciculus thalamomammillaris [Vicq d'Azyri]) (0. T. bundle of Vicq d'Azyr). FIG. 173. Capsula interna _, Nucleus ventralis thalami (ant.) - Putamen \ / Globus pallidus, pars lateralis Globus pallidus, pars medialis' Commissura anterior cerebri Nucleus lateralis thalami / Nucleus anterior thalami (a) /Capsula ventralis nucl. ant. thalami B5 ' ' -Hi X /Taenia thalami . Fasciculus thalamo-mammillaris [Vicq d'Azyri] "T Stratum griseum centrale *--j Pedunculus thalami medialis y: •,/! ?', \ x-Columna fornicis V' -'-.'/ *• \Ansa lenticularis, pars ventralis Frontal section through a normal human brain at level of anterior part of thalamus. (After C. von Monakow, Arch. f. Psychiat., Berl., Bd. xxvii., 1895, Taf. iv., Fig. 33.) (7) Pedunculomamnrillary fasciculi (fasciculi pedunculomammillares) . (a) Tegmental part (pars tegmentalis). (b) Basilar part (pars basilaris). 362 LABORATORY MANUAL OF HUMAN ANATOMY (8) Peduncular loop (ansa peduncularis) . (a) Lenticular loop (ansa lenticularis) . (b) Inferior peduncle of thalamus (pedunculus thalami inferior) Sections of Thalamencephalon (Sectiones thalamencephali). (1) Zonal layer (stratum zonale). (2) Anterior nucleus of thalamus (nucleus anterior thalami). (3) Medial nucleus of thalamus (nucleus medialis thalami). (4) Lateral nucleus of thalamus (nucleus lateralis thalami). FIG. 174. Radiatio corporis callosi Bulbus cornu posterioris Calcar avis Hippo- campus Corpora quadrige- mina Nucleus colliculi — J!/f ••/, inferioris Splenium corporis i— .-' callosi Telachorio- idea ven- triculi tertii Corpus .pineale Cornu pos- terius ven- triculi lateralis Glomus chorio- ideum Aquaeduc- %'#f tus cerebri £;>- M^!l:~x:; Nucleus N.. -$&_,',_ % J\ trochlearis Fasciculus longitudi- ""^s nal is medialis '<» Cerebellum Brachium pontis-- Flocculus-"" Pyramis medullae oblongatae--' Radiatio "~' occipito- thalamica s__- Eminentia jJ collateralis x___Fissura collateralis Lemniscus lateralis Brachium con- junctivum stratum gri- seum centrale Lemniscus medialis "^ ^G Upper ends °f the Py^^ds of the medulla oblongata, through the splenium Wi?n 190C3 3Aufln ^ ? ° P°Steri°r parts of the lateral ventricles. (After Toldt, Anat. Atlas, (5) Medullary layers of thalamus (laminae medullares thalami). (6) Nucleus of medial geniculate body (nucleus corporis geniculati me- dialis). (7) Nucleus of lateral geniculate body (nucleus corporis qeniculati lat- eralis). (8) Nucleus of habenula (nucleus habenulae). Retroflex fasciculus (fasciculus retroflexus [Meynerti]). Sections of Telencephalon (Sectiones telencephali). (1) Cortical substance (substantia corticalis). Observe the difference in macroscopic appearance in different areas in the cortex. (2) Semioval centre (centrum semiovale). DISSECTION OF THE HEAD AND NECK 363 FIG. 175. Ventriculus lateral! (pars centralist Plexus chorioid- x eus ventriculi lateralis Nucleus caudatus Massa inter- media Nucleus (Putamen- Globus pallidus lenti- formis Capsul externa— Claustrum fe Ansa peclun-'';.' cularis ^ Tractus options, -.- Pedunculus f, thalami ''"••• inferior £. Cornu inf erius s' v ventriculi £ lateralis >* Digitatione.s hippocampi N. oculomotoriu Corpus callosum Fornix ./*Ventriculus tertius Thalamus Fasciculus ^ thalamo- mammillaris Tegmental ^.bundle to the lenticular nucleus - Nucleus hypothalam- icus (Corpus Luysi) Substantia nigra pedunculi Corpus •-mammillare Fossa » interpedun- cularis Pons (Varioli) Section through the third ventricle, cerebral peduncles, and corpora mammillaria. (After Toldt, Anat. Atlas, Wien, 1903, 3 Aufl., p. 792, Fig. 1219.) FIG. 176. Nucleus caudatus (caput) Capsula interim (pai frontalis) {Puta- f men .XJS1. Globus pal- ! lidus Lamina medullaris-- Capsula externa Claustrum -J Fissura longitudinalis cerebri Corpus callosum Cornu anterius ventriculi lateralis lexus chorioi- deus ventriculi lateralis Septum pellucidum TVna Foramen inter- vetitriculare i Monroi) Substantia per- forata anterior Uncus Commissura anterior (cerebri) Section through the optic chiasma and anterior cerebral commissure. 1903, 3 Aufl., p. 793, Fig. 1221.) fornicis _. Fissura cerebri | lateralis [Sylvii] jf-^Gyri insulae Recessus opti- cus ventnculi tertii ractus opticus Chiasma opti- cum (most pos- terior part) '"* Commissura inferior (Guddeni i (After Toldt, Anat. Atlas, Wein, 364 LABORATORY MANUAL OF HUMAN ANATOMY (3) Decursus ("running down") of cerebral fibres (decursus fibrarum cerebralium) . (4) Arcuate fibres of cerebrum (fibrae arcuatae cerebri). (a) Cingulum (cingulum) ("girdle"). (b) Superior longitudinal fasciculus (fasciculus longitudinalis superior). (c) Inferior longitudinal fasciculus (fasciculus longitudinalis in- ferior). (d) Uncinate ("hooked") fasciculus (fasciculus uncinatus). (e) Radiation of corpus callosum (radiatio corporis callosi). (ea) Frontal part (pars frontalis) (0. T. forceps minor). (eb) Parietal part (pars parietalis). (ec) Temporal part (pars temporalis) . (ed) Occipital part (pars occipitalis) (0. T. forceps major). (/) Tapetum (tapetum) (" carpet" or " tapestry"). (5) Lentiform nucleus (nucleus lentiformis) (0. T. lenticular nucleus). (a) Putamen (putamen) (" shell" or " paring"). (b) Globus pallidus (globus pallidus) (" pale sphere"). (6) Claustrum (claustrum) ("bulwark" or "barrier"). (7) External capsule (capsula externa). (8) Internal capsule (capsula interna). (a) Knee of internal capsule (genu capsulae internae). (b) Frontal part of internal capsule (pars frontalis capsulae in- ternae) (0. T. anterior limb). (c) Occipital part of internal capsule (pars occipitalis capsulae internae) (0. T. posterior limb). (9) Amygdaloid nucleus (nucleus amygdalae) ("almond" nucleus). (10) Corona radiata. (a) Frontal part (pars frontalis). (b) Parietal part (pars parietalis). (c) Temporal part (pars temporalis). (d) Occipital part (pars occipitalis). (11) Radiation of corpus striatum (radiatio corporis striati). (12) Oecipitothalamic radiation (radiatio occipitothalamica [Gratioleti]) (0. T. optic radiation). (13) Anterior commissure of cerebrum (commissura anterior cerebri). (a) Anterior part (pars anterior). (b) Posterior part (pars posterior). CONDUCTION PATHS OF THE NEKVOUS SYSTEM. The student should now take up systematically the study of the various motor, sensory, and associative conduction paths of the nervous system. For frequent consultation, Section VI. of ' The Nervous System and its Constituent Neurones" (D. Ap- pleton and Co., New York) is recommended. A study of sections of various spinal cords in which secondary degenerations have DISSECTION OF THE HEAD AND NECK 365 taken place is desirable for a thorough understanding of the complex relations which exist. Descending Fibre Systems in Spinal Cord. (1) Pyramidal tracts (anterior and lateral), from cortex of central gyri of same and opposite side. (2) Anterior marginal bundle from nucleus fastigii. (3) Sulcomarginal fasciculus = path from superior colliculus of corpora quadrigemina. (4) Descending paths in fasciculus lateralis proprius. (a) Tract from Deiters's nucleus to lateral funiculus. (6) Tract from red nucleus of opposite side to lateral funiculus. (c) Tract from nuclei laterales superior, medius, inferior, to lateral funiculus. (5) Descending paths in posterior funiculus. (a) Descending limbs of bifurcation of posterior root-fibres. (b) Endogenous fibres of posterior funiculi (comma bundle, ven- tral area, oval centre, median triangle). (6) Other descending paths in lateral and anterior funiculi. (a) Endogenous fibres (tautomeric and heteromeric). Ascending Fibre Systems in Spinal Cord. (Vide Fig. 103.) (1) Direct continuation of ascending limbs of bifurcation of posterior root-fibres to nucleus funiculi gracilis, nucleus funiculi cuneati, and partly to cerebellum. Secondary path: from nuclei of dorsal funiculi, through decussa- tio lemniscorum to stratum interolivare lemnisci of opposite side, and then through lemniscus median's to [ventro-] lateral nucleus of thalamus. Tertiary path : from ventrolateral nucleus of thalamus to cortex of central gyri (somaesthetic area). (2) Fibre systems leading from the end-stations of posterior root-fibres in the spinal cord to higher centres, (a) Cerebellospinal fasciculus (fasciculus cerebellospinalis) (0. T. direct cerebellar tract), from nucleus dorsalis of Clarke to cerebellum. (6) Gowers's tract (fasciculus anterolateralis superficialis [Gow- ersi]), from base of anterior horn to cerebellum. (c) From posterior horn upward in lateral limiting layer of gray matter, and in opposite anterior funiculus. (3) Fibre systems from some of cells in anterior horns upward in fascicu- lus anterior proprius and fasciculus lateralis proprius to formatio reticularis. Fibre Systems of Cerebral Nerves. Like the motor spinal nerves, the motor cerebral nerves arise from nuclei of origin (nuclei originis) in the brain-stem, the fibres leaving the central system to terminate in the muscles. 366 LABORATORY MANUAL OF HUMAN ANATOMY Like the sensory spinal nerves, the sensory cerebral nerves arise from ganglia outside the central nervous system and their axones terminate in certain end-nuclei (nuclei terminates) inside the central system; in these end-nuclei are cells which give off the axones of secondary fibre systems. OLFACTORY NERVES (NN. OLFACTORII). Nuclei originis: bipolar cells of regio olfactoria of nasal mucous mem- brane. Nuclei terminates : in olfactory glomeruli of bulbus olf actorius. Secondary path: from mitral cells of bulbus olf actorius through tractus olfactorius to — (a) Gray matter of trigonum olfactorium. (b) Through stria olfactoria lateralis to uncus and thence to hippo- campus and gyrus cinguli. (c) Through stria olfactoria intermedia to substantia perforata ante- rior. (d) Through stria olfactoria medialis to gyrus subcallosus. BIPOLAR CELLS OF RETINA (analogous, for visual path, to sensory fibres of pos- terior roots of spinal nerves). Nuclei terminates: ganglion cell layer of retina, Secondary path: from ganglion cell layer of retina, through (badly named) N. OPTICUS, chiasma opticum, and tractus optici, to — (a) Corpus geniculatum laterale. (b) Pulvinar thalami. (c) Superficial and middle gray strata of superior colliculus of corpora quadrigemina. Tertiary paths: (a) From corpus geniculatum laterale and pulvinar thalami, through radiato occipitothalamica [Gratioleti], to cortex of occipital lobe about the fissura calcarina. (b) From middle gray layer of colliculus superior, through decussatio tegmenti dorsalis of Meynert and fasciculus longitudinalis me- dialis of opposite side, to eye-muscle nuclei and spinal cord ; this is the so-called "optic-acoustic reflex path" (Held), OCULOMOTOR NERVE (N. OCULOMOTORIUS). Nuclei originis: nucleus of oculomotor nerve (nucleus N. oculomotorii) in tegmentum of cerebral peduncle. Cortical control: (a) From cortex of central gyri through capsula interna (?). (b) From cortex about fissura calcarina to superior colliculus and then through optic-acoustic reflex path. TROCHLEAR NERVE (N. TROCHLEARIS). Nucleus originis: nucleus of trochlear nerve (nucleus N. trochlearis) in isthmus rhombencephali on opposite side, through decussatio nervorum trochlearium. Cortical control: probably same as for N. oculomotorius. DISSECTION OF THE HEAD AND NECK 367 TRIGEMINAL NERVE (N. TRIGEMINUS). (A) Motor part (portio minor). Nuclei originis : (a) Principal motor nucleus (nucleus motorius princeps N. trigemini) in pars dorsalis pontis. (b) Lesser motor nuclei (nuclei motorii minores N. trigemini). (ba) Cells of locus caeruleus. (bb) Cells along descending or mesencephalic root (nucleus radicis descendentis ) . Cortical control: from lower third of gyrus centralis anterior and feet of frontal gyri, through capsula interna and partly through basis pedunculi (pyramidal tract), partly through area of lemniscus me- dialis (accessory lemniscus of v. Bechterew). (B) Sensory part (portio major). Nucleus originis: semilunar ganglion (ganglion semilunare [Gasseri]). Nuclei terminales: (a) Main sensory nucleus (nucleus sensibilis N. trigemini). (b) Nucleus of spinal tract (nucleus tractus spinalis N. trigemini). Secondary paths : (a) To opposite medial lemniscus and through it to [ventro-] lateral nucleus of thalamus. (b) To substantia reticularis alba of same and of opposite side, and through it to [ventro-] lateral nucleus of thalamus. Tertiary path: from [ventro-] lateral nucleus of thalamus to central gyri (somaesthetic area). ABDUCENT NERVE (N. ABDUCENS). Nucleus originis: nucleus of abducent nerve (nucleus N. abducentis) in pars dorsalis pontis. Cortical control: (a) Pyramidal tract (*?). (b) " Accessory lemniscus" (?). (c) Indirectly through optic-acoustic reflex path. FACIAL NERVE (N. FACIALIS). Nucleus originis: nucleus of facial nerve (nucleus N. facialis) in ventral lateral part of pars dorsalis pontis close to medulla oblongata. Cortical control: (a) Through pyramidal tract of the same and of the opposite side. (b) Through the "accessory descending lemniscus" of the same and of the opposite side (Hoche). INTERMEDIATE NERVE (N. INTERMEDIUS). Nucleus originis: geniculate ganglion (ganglion geniculi). Nucleus terminalis: probably the same as for N. vagus and N. glosso- pharyngeus. Secondary path: uncertain. ACOUSTIC NERVE (N. ACUSTICUS). (A) Vestibular nerve (N. vestibularis) . Nucleus originis: vestibular ganglion (ganglion vestibulare) . Nuclei terminales : (a) Lateral nucleus (nucleus N. vestibularis lateralis [Deitersi]). 368 LABORATORY MANUAL OF HUMAN ANATOMY (b) Medial nucleus (nucleus N. vestibularis medialis). (c) Superior nucleus (nucleus N. vestibularis superior). (d) Nucleus of descending root (nucleus radicis descendentis) . Secondary paths : (a) From lateral nucleus of Deiters to lateral funiculus of cord. (b) From medial and superior nuclei to fasciculi longitudinales me- diales of 'two sides for eye-muscle nuclei, etc. (c) From lateral and superior nuclei to nucleus fastigii, nucleus den- tatus, and cortex vermis. (d) From all the terminal nuclei, through the substantia reticularis alba to the [ventro-] lateral nuclei of the thalamus (?). Tertiary path: from [ventro-] lateral nuclei of thalamus to central gyri (somaesthetic area). (B) Cochlear nerve (N. cochlearis). Nucleus originis : spiral ganglion (ganglion spirals). Nuclei terminates : (a) Ventral nucleus (nucleus N. cochlearis ventralis). (b) Dorsal nucleus (nucleus N. cochlearis dorsalis [nucleus tuberculi acustici] ) . Secondary paths: (a) Fibres from ventral nucleus through corpus trapezoideum to upper olives, and through lateral lemniscus to nucleus of lat- eral lemniscus, inferior colliculus, middle gray layer of supe- rior colliculus, and through brachium quadrigeminum inferius to medial geniculate body, possibly some even to temporal cortex. (b) Fibres from dorsal nucleus through stria medullares to trapezoid body. Tertiary paths: from end-stations of secondary path (a), especially from nucleus colliculi inferioris and nucleus corporis geniculati me- dialis, through capsula interna and pars temporalis of corona radiata, to gyrus temporalis superior (junction of third and fourth fifths) and adjacent gyri temporales transversi. [When this cortical area is diseased, the patient has " word-deafness."] GLOSSOPHARYNGEAL AND VAGAL NERVES (N. GLOSSOPHARYNGEUS ET N. VAGUS). (A) Motor part. Nuclei originis: (a) Dorsal nucleus (nucleus dorsalis Nn. glossopharyngei et vagi) in medulla oblongata just medial from ala cinerea. (b) Ventral nucleus (nucleus ambiguus) in the formatio reticularis of medulla oblongata just dorsal from nucleus olivaris accesso- rius dorsalis. Cortical control: (a) Pyramidal tract from central gyri. (b) Accessory lemniscus (?). (B) Sensory part. Nuclei originis: (a) For N. glossopharyngeus. (aa) Superior ganglion (ganglion superius). (ab) Petrosal ganglion (ganglion petrosum). (b) For N. vagus. DISSECTION OF THE HEAD AND NECK 369 (ba) Jugular ganglion (ganglion jugular e). (bb) Ganglion nodosum (ganglion nodosum) ("knotty" gan- glion). Nuclei terminates: (a) Nucleus of ala cinerea (nucleus alae cinereae). (b) Nucleus of tractus solitarius (nucleus tractus solitarii). (c) Commissural nucleus (nucleus commissuralis) (O. T. ganglion commissurale). Secondary paths: (a) From nuclei terminates through fibrae arcuatae internae to oppo- site stratum interolivare lemnisci and thence through lemniscus medialis to [ventro-] lateral nucleus of thalamus. (b) From nuclei terminates through lateral bundles of substantia reticularis alba of same and of opposite side to [ventro-] lateral nuclei of thalamus. (c) From nuclei terminates through medial portion of corpus resti- forme to nucleus fastigii and cortex vermis. Tertiary path: probably from [ventro-] lateral nucleus of thalamus through capsula interna and corona radiata to central gyri (somaes- thetic area). Conduction Paths of Cerebellar Peduncles. PATHS OF CORPUS RESTIFORME (0. T. INFERIOR PEDUNCLE). (a) Paths of corpus resti forme proper. (aa) Cerebellospinal fasciculus (fasciculus cerebellospinalis, or, better, fasciculus spinocerebellaris dorsolateralis) (0. T. direct cerebellar tract). (ab) External arcuate fibres (fibrae arcuatae externae ) = crossed and uncrossed medullated axones from nuclei funiculi cuneati et gracilis. (ac) Cerebello-olivary fibres (fibrae cerebelloolivares) , partly as- cending, partly descending. (ad) Medullated axones from nuclei laterales to cerebellum. These paths (aa, ab, ac, and ad] run into the cerebellum to end in the cortex of the vermis; they give off collaterals and some terminals to the nucleus fastigii, nucleus dentatus, nucleus emboliformis, and nucleus globosus as these are passed. (b) Paths of medial part of corpus restiforme. (ba) Ascending paths, corresponding to secondary paths from the nuclei terminates of the Nn. vagus, glossopharyngeus, ves- tibularis, et trigeminus to the nucleus fastigii and cortex vermis. (bb) Descending paths from nucleus fastigii to opposite nucleus N. vestibularis [Deitersi]. This connects at Deiters' nu- cleus with the path leading to the lateral funiculus of the spinal cord. PATHS OF BRACHIUM PONTIS (0. T. MIDDLE CEREBELLAR PEDUNCLE). (a) Cerebellopontal paths, from cortex of hemisphaerium cerebelli to nuclei pontis of same and of opposite side. 24 370 LABORATORY MANUAL OF HUMAN ANATOMY 1C-' c, DISSECTION OF THE HEAD AND NECK 371 Horizontal section through the right cerebral hemisphere cut at a distance of 61 mm. below its superior border ; natural size. AM, claustrum; C, cuneus; CA, hippocampus (comu ammonis) ; Cc(g), genu corporis callosi ; Ce, capsula externa ; Cg, gyrus dentatus ; Cia, pars frontalis capsulae internae ; Ci(g), genu capsulae internae ; Cing, horizontal bundle of the cingulum ; Cing(p), posterior bundle of the cingulum ; dp, pars occipi- talis capsulae internae ; Ctrl, retrolenticular portion of internal capsule ; cm, sulcus cinguli ; CO, centrum semiovale ; cop, commissura posterior cerebri ; Csc, gyrus subcallosus ; do, cornu posterius ventriculi lateralis ; FI, gyrus frontalis superior ; Fz, gyrus frontalis medius ; Fs, gyrus frontalis inferior ; /1? sulcus rontalis superior ; /2) sulcus frontalis inferior; F3(c), pars triangularis gyri frontalis inferioris ; Fli, fasciculus longitudinalis inferior; FM, fasciculus retroflexus Meynerti ; Fm', fasciculus inferior or minor of the fornix ; Gh, nucleus habenulae ; Gp, corpus pineale ; la, insula (pars anterior) ; Jp, insula (pars posterior) ; K, fissura calcarina ; K\.po, union of the flssura calcarina with the fissura parieto- occipitalis; LI, gyrus cinguli; L(i), isthmus gyri fornicati ; Ic, lamina cornea and fibres of the taenia semicircularis ; Lg, gyrus lingualis ; Ime, lamina medullaris lateralis nuclei lentiformis ; Imi, lamina medullaris medialis nuclei lentiformis ; Ims, lamina medullaris superficialis ; mFi, facies medialis gyri frontalis superioris ; NC, caput nuclei caudati ; NC', cauda nuclei caudati ; Ne, nucleus lateralis thalami ; NL^, NL», globus pallidus (of nucleus lentiformis) ; NL%, putamen (of nucleus lentiformis) ; 0\, 02, gyri occipitales ; oa, sulcus occipitalis anterior of Wernicke ; OF, fasciculus occipito-frontalis ; oi, sulcus interoccipitalis ; Op,F3, pars opercularis gyrus frontalis inferioris ; OpR, Rolandic operculum ; Pa Th, pedunculus anterior thalami ; po, fissura parieto-occipitalis ; Pul, pulvinar ; ircl, cuneo-limbic fold; irplp, posterior parieto-limbic fold; RTh, radiatio occipito-thalamica [Gratioleti] ; S(p), ramus posterior fissurae cerebri lateralis Sylvii; S(v), ramus ascendens; sec, sinus corporis callosi; Sgc, sub- stantia grisea centralis; Sge, subependymal gray matter; H, gyrus temporalis superior; 7J>, gyrus temporalis medius ; ti, sulcus temporalis superior ; Tap, tapetum ; tec, taenia tecta ; Tga, anterior pillar of the fornix; TgV, ventriculus lateralis; Th, thalamus; Tp, gyrus temporalis transversus; tp, sulcus temporalis transversus ; V^, ventriculus tertius ; V, stripe of Vicq d'Azyr ; VA, fasciculus thalamo- mammillaris Vicq d'Azyri; TJ, cornu anterius ventriculi lateralis; Vsl, cavum septi pellucidi ; Zrt zona reticularis. (After J. Dejerine, Anatomie des Centres Nerveux, Paris, 1895, p. 408, Fig. 226.) 372 LABORATORY MANUAL OF HUMAN ANATOMY (b) Pontocerebellar paths, from nuclei pontis to cortex of hemisphaerium cerebelli of same and of opposite side. PATHS OF BRACHIUM CONJUNCTIVUM (0. T. SUPERIOR CEREBELLAK PEDUNCLE). (a) Paths from nucleus dentatus cerebelli through brachium conjunctivum to tegmentum of cerebral peduncle, there to decussate in large part in the decussatio brachii conjunctivi, then to give off large numbers of collaterals to the nucleus ruber, and finally, joining the fibres of the lemniscus medialis, to end in the [ventro-] lateral nucleus of the thalamus. There it connects with the thalamocortical path to the central gyri (somaesthetic area). This path influences the spinal cord in at least two ways : (1) By collateral fibres which leave main axones soon after exit from the cerebellum and pass down to the spinal cord (ramus de- scendens of Ramon y Cajal). (2) Through the red nucleus which sends a path to the lateral funiculus. (b) Path from spinal cord to cerebellum running in Gowers' tract upward to pons and corpora quadrigemina, then hooking around N. tri- geminus and running, in velum medullare anterius, close to bra- chium conjunctivum, to cerebellar vermis. Conduction Paths of Diencephalon and Telencephalon. I. PROJECTION FIBRE SYSTEMS. These are the fibre systems which connect the gray matter of the telencephalon (pallium, nucleus caudatus, nucleus lentiformis, rhinen- cephalon) with lower parts of the nervous system (thalamus, brain- stem, spinal cord). (A) Ascending projection systems (corticopetal paths). (1) Uppermost neurone systems of general sensory path. The medul- lated axones pass from the cells in the [ventro-] lateral nucleus of the thalamus, chiefly through the posterior third of the capsula interna and corona radiata, to the cortex of the cen- tral gyri (somaesthetic area) ; a few fibres go through or around the nucleus lentiformis, and by way of the capsula externa to the cortex. (2) Upper part of visual conduction path. The medullated axones pass from the cells in the nucleus corporis geniculati laterale and pul- vinar thalami, through the radiatio occipitothalamica, to the cortex about the fissura calcarina. (3) Upper part of auditory conduction path. The medullated axones pass from the cells in the nucleus corporis geniculati medialis and nucleus colliculi inferior, by way of the posterior part of the capsula interna, lateralward to the gyrus temporalis superior (junction of third and fourth fifths), and adjacent gyri tem- porales transversi. (B) Descending projection systems (corticofugal paths). (1) Pyramidal tract (fasciculi pyramidales] , from large pyramidal cells of central gyri and lobulus paracentralis, through corona radiata and through knee and anterior two-thirds of occipital limb of capsula interna (head-movement fibres in front, arm DISSECTION OF THE HEAD AND NECK 373 fibres in middle, and leg fibres behind), into basis pedunculi, to motor nuclei of cerebral nerves and to anterior horns of spinal cord. (2) "Accessory lernniscus" of v. Bechterew, from cortex to motor nuclei of cerebral nerves. (3) Frontal corticopontile path (fasciculus corticopontilis frontalis), from posterior part of frontal lobe, through frontal limb of capsula interna and through medial part of basis pedunculi (Arnold's bundle), to nuclei pontis. (4) Temporal corticopontile path (fasciculus corticopontilis tempo- ralis ) . (5) Occipitomesencephalic path (fasciculus occipitomesencephalica) (0. T. secondary optic radiation of Flechsig), fibres from visual sense area about fissura calcarina, downward through occipito- thalamic radiation to superior colliculus. (6) Projection fibre systems of central olfactory paths. (a) Hippocanipo-mammillary fibre system, going from cells in hippocampus, through fornix and columna for- nicis, to nuclei corporis mammillaris of same and of opposite side; there connecting with — (aa) Principal mammillary fasciculus (fasciculus mam- millaris princeps), which divides into — (aaa) Thalamomammillary fasciculus (fascicu- lus thalamomammillaris [Vicq d'Azyri]), going to nucleus anterior thalami, and (aab) Tegmental part of pedunculomammillary fasciculus (fasciculus pedunculomammil- laris, pars tegmentalis), to the tegmen- tum of the cerebral peduncle. (ab) Basilar part of pedunculomammillary fasciculus (fasciculus pedunculomammillaris, pars basilaris) (0. T. peduncle of mammillary body). II. ASSOCIATIVE FIBRE SYSTEMS. (A) Connecting different parts of same hemisphere. (a) Those with short axones, including the fibrae propriae of the gyri cerebri. (b) Those with long axones. (ba) Cingulum (cingulum) (" girdle"), in the gyrus cinguli and gyrus hippocampi. (bb) Superior longitudinal fasciculus (fasciculus longitudinalis superior), extending between lobus frontalis and lobus occipitalis. (be) Inferior longitudinal fasciculus (fasciculus longitudinalis inferior), between lobus occipitalis and more anterior parts of brain. (bd) Uncinate fasciculus (fasciculus uncinatus), between uncus and base of lobus frontalis. (B) Connecting the two hemispheres with each other (commissural fibre sys- tems). (a) Corpus callosum (corpus callosum) ("callous" or " hard" body). (b) Anterior commissure of cerebrum (commissura anterior [cerebri]). (c) Commissure of hippocampus (commissura hippocampi). FIG. 178. Stratum album profundum Nucleus N. oculomotorii Commissurae nuclei colliculi inferioris \ Fasciculus retroflexus [Meynerti] Lemniscus medialis Nucleus. colliculi" inferioris i Radix N - trochlearis Brachium conjunct! vumv Radix descendens-V — N. trigemini \ Locus caeruleus— \- Radix N. trigemini (mot.) Radix N. \ trigemini (sens.) Nucleus moto- rius princeps N. trigemini — Nucleus N. trigemini (sens.)-— Nucleus N. vestibuli - lateralis Corpus resti-... Jt forme Nucleus et radix N. ve*- tibuli Nucleus^ cochleae dorsalis Corpus restifonne__.. Tractus solitarius et nucleus alae cinereae Nucleus funiculi^ cuneati Fasciculus cuneatus — Nucleus funiculi gracilis__ Fasciculus gracilis- The nuclei of the cerebral nerves. Dorsal surface of model. (From Sabin, An Atlas of the Medulla and Midbrain, Baltimore, 1901, Plate iii.) Corpus restifonne Radix N. facialis - — (genu internum) — Nucleus N. abducentis ..Fasciculus longitu- dinalis medialis Nucleus olivaris inferior Nucleus N. hypoglossi DISSECTION OF THE HEAD AND NECK 375 ORGAN OF VISION (ORGAN ON VISUS). This includes the eyeball (bulbus oculi), the optic nerve (N. options), and the accessory organs of the eyeball (organa oculi accessories). The latter, including the extrinsic muscles of the eye, orbital fasciae, eyelids and eyebrows, conjunctiva, and lacri- mal apparatus, as well as the optic nerve, have already been studied. The eyeball itself should now be examined. The student should provide himself with several eyeballs from the ox and pig; some of these may be dissected fresh, FIG. 179. Linea visus (line or axis of vision) Axis optica (axis of the optical system, ocular axis) ~~1 . Vertex corneae Camera oculi anterior (anterior chamber) Camera oculi posterior ^^TZ- — H^-^^X^ Cornea. (posterior chamber) >O^\ I IV? \^V Iris Processus ciliaris . Zonula, ciliaris - ^ [Zinni] Lens crystallina-- ,. Conjunctiva bulbi -M. ciliaris .-.Pars ciliaris retinae Ora serrata -Nodal point Equatorial diameter -Pars optica retinae Corpus vitreunv Papilla N.optici-- Excavatio papillae N. optici-' *-»Fovea centralis of the macula lutea ill. __.N. opticus Schematic section in the horizontal meridian of the right eyeball. (After Toldt, Anat. Atlas, Wien, 1903, 3 Aufl., p. 892, Fig. 1334.) others after hardening in formalin. Sections in different planes should be made of eyeballs hardened in formalin. These may easily be permanently preserved in formalin gelatin. The eye- balls should first be cleaned. Remove the conjunctiva, eye- muscles, fat, and capsule of Tenon. This is best done by grasp- ing the conjunctiva and fascia bu^bi with the point of the forceps close to the limbus corneae and snipping through them with fine 376 LABORATORY MANUAL OF HUMAN ANATOMY sharp scissors, going right around the cornea in this way. All the soft parts may now be stripped off the sclera back as far as the N. opticus. Take two eyes, hardened in formalin, and divide one by a sagittal section into a medial and a lateral half, and the other by a coronal section through the equator into an anterior and a posterior half. With a sharp razor this can be easily accomplished in formalinized eyes without freezing. Ascertain the exact meaning of the following terms : (a) Anterior pole (polus anterior}. (b) Posterior pole (polus posterior}. (c) Equator (aequator}. (d) Meridians (meridiani}. (e) External axis of eyeball (axis oculi externa}. (f) Internal axis of eyeball (axis oculi interna}. (g) Optic axis (axis optica). (h) Line of vision (linea visus}. And of the two embryological terms : (i) Ophthalmic vesicle (vesicula ophthalmica} . (j) Ophthalmic cup (caliculus ophthalmicus} . Note that the eyeball possesses the following: (a) Fibrous tunic (tunica fibrosa oculi}. (aa) Cornea. (aft) Sclera. (6) Vascular tunic (tunica vasculosa oculi}. (ba} Chorioid coat (chorioidea} . (bb) Ciliary body (corpus ciliare}. (be} Iris (iris}. (c} Pigment layer (stratum pigmenti}. (d) True nervous portion of eye (retina}. (e} Anterior and posterior chambers (camera oculi anterior, posterior}, (f} Vitreous body (corpus vitreum}. (g} Crystalline lens (lens crystallina}. (h} Ciliary zonule (zonula ciliaris [Zinni]}. Fibrous Coat of Eye (Tunica fibrosa oculi). Make an incision with a very sharp knife through the sclera of an eyeball at the equator ; let the knife cut only as far as the black chorioidea, then lay it aside. Catch the edge of the sclera in forceps, and with sharp fine scissors cut through the sclera all the way around the eyeball, along the line of the equator. Raise the anterior and posterior segments of the sclera from the subjacent parts. In turning the anterior half forward, over- come the resistance met near the margin of the cornea, due to the attachment of the M. ciliaris to the deep surface of the sclera, DISSECTION OF THE HEAD AND NECK 377 with the probe or the blunt point of the closed forceps; on breaking through this resistance the so-called " aqueous humor" escapes. To separate completely the posterior segment of the sclera from the rest of the eyeball, cut through the fibres of the FIG. 180. Sinew radiation of the M. rectus superior •__ Sclera Aa. and Vv. ciliares anteriores Circulus arteriosus major |, Angulus iridis Sinus venosus sclerae (canalis Schlemmi) Conjunctiva bulbi .._ Episcleral connective tissue with Aa. and Vv episclerales Lig. pectinatum iridis Rima cornealis (groove for the cornea) _ Limbus corneae (border of the cornea) Iris (facies._ anterior) Camera oculi anterior Cornea (sub- stantia propria Facies posterior corneae Epithelium corneae Lamina elastica anterior fBow- mani] Lamina elastica posterior [Bes- eemed] with the M. endo- thelium camerae anterioris Pars ciliaris retinae Stratum pigmenti retinae Pars optica retinae Ora serrata Chorioidea Spatium perichorioideale with the lamina suprachorioidea I .Fibrae meridional es [Brueckei] ^.Fibrae circulares [Muelleri] .-Processus ciliaris ^,. Fibrae zonulares . Zonula ciliaris [Zinni] g. Spatia zonularia Camera oculi posterior Epithelium lentis -.:- Capsula lentis substantia jorticalis M. ciliaris Jubstantia lentis M. sphincter pupillae Stroma iridis Facies posterior iridis with the stratum pigmenti The upper half of a section in the vertical meridian of the anterior part of the eyeball. (After Toldt, Anat. Atlas, Wien, 1903, 3 Aufl., p. 893, Fig. 1337.) N. opticus in a plane corresponding to the inner surface of the sclera. Place the denuded eyeball in a dish of water and study the sclera and cornea. 378 LABORATORY MANUAL OF HUMAN ANATOMY In the SCLEEA (0. T. sclerotic coat, or white of the eye) exam- ine the following : (a) Sulcus of the sclera (sulcus sclerae). Make a meridional incision through the sclerocorneal junction and note — (b) Cleft for the cornea (rima cornealis). (c) Venous sinus of the sclera, or canal of Schlemm (sinus venosus sclerae [canalis Schlemmi, Lauthi]). (d) Brown layer (lamina fusca). To what is this due? (e) Perforated layer of sclera (lamina cribrosa sclerae). In the CORNEA study the following : (a) Ring of conjunctiva (annulus conjunctivae). (b) Vertex of cornea (vertex corneae). (c) Border of cornea (limbus corneae). (d) Anterior surface (fades anterior). (e) Posterior surface (fades posterior). Make a razor section or a frozen section through the cornea, and under the dissecting microscope observe — A. and V. ciliaris anterior A. and V. conjunctivalis- posterior A. and V. conjuncti- valis anterior Sinus venosus V< sclerae (Canalis Schlemmi) FIG. 181. -M. rectus medialis A. and V. episcleralis V. vorticosa (vortex vein) A. ciliaris posterior longa A. and V. ciliaris pos- terior brevis Vessels of the va- ^ gina N. optici Circulus anteri- ijor in cross-section N. opticus A. and V. cen- tralis retinae Scheme of the arrangement of blood-vessels in the eyeball. Horizontal section. (After Th. Leber.) (From Toldt, Anat. Atlas, Wien, 1903, 3 Aufl., p. 897, Fig. 1351.) (f) Epithelium of cornea (epithelium corneae). (ff) Anterior elastic layer (lamina elastica anterior [Bowmani]) (0. T. Bowman's membrane). (h) Proper substance (substantia propria). DISSECTION OF THE HEAD AND NECK 379 (») Posterior elastic layer (lamina elastica posterior [Demoursi, Desce- meti]) (0. T. Descemet's membrane). (,;') Endothelium of anterior chamber (endothelium camerae anterioris). Vascular Coat of Eye (Tunica vasculosa oculi). In the CHORIOID COAT (chorioidea) study the following: (a) Suprachorioid layer (lamina suprachorioidea) . (b) Perichorioideal space (spatium perichorioideale) . (c) Vascular layer (lamina vasculosa). Observe the Vv. vorticosae. If the pigment be washed out with a camel's-hair brush, these will become very evident. (d) Choriocapillary layer (lamina choriocapillaris) (0. T. tunica Ruysch- iana) . Between (c) and (d) observe the Aa. ciliares posteriores breves. In the CILIARY BODY (corpus ciliare) the ciliary wreath (corona ciliaris) and the ciliary disk (orbiculus ciliaris) are to be studied. To expose the ciliary wreath make a coronal section through an eyeball a little in front of the equator, and remove cautiously the vitreous humor from the anterior segment of the eyeball. Ex- amine— FIG. 182. - Orbiculus ciliaris Plicae ciliares — .Corpus ciliare Processus ciliares Iris (facies posterior) __Aequator lentis (lens capsule separated off a little) Lens crystallina ( facies posterior) A part of the ciliary processes and ciliary folds , enlarged. (After Toldt, Anat. Atlas, Wien, 1903. 3 Aufl., p. 895, Fig. 1342.) (a) Ciliary processes (processus ciliares). (b) Ciliary folds (plicae ciliares). With a camePs-hair brush wash out the pigment and note the exact disposition of the processes and folds. The ciliary wreath may be exposed from in front in another eyeball as follows : remove cornea with scissors at sclerocorneal junction. Make four meridional cuts through sclera and reflect 380 LABORATORY MANUAL OF HUMAN ANATOMY its parts backward, separating each from the M. ciliaris; pin these down to the bottom of a cork-lined tray. Examine the iris and then cautiously remove it. In the ciliary disk (orbiculus ciliaris) examine— (a) Ciliary muscle (M. ciliaris). (aa) Meridional fibres (fibrae meridionales [Brueckei]). (ab) Circular fibres (fibrae circulares [Mulleri]). These are best distinguished in a thin meridional section through the corpus ciliare under the microscope. (b) Ganglionic ciliary plexus (plexus gangliosus ciliaris}. Look for it at the junction of the chorioidea with the corpus ciliare. In the DIAPHRAGM OF THE EYE (iris) study — (a) Pupillary margin (mar go pupillaris). (b) Ciliary margin (mar go ciliaris). (c) Anterior surface (fades anterior). (d) Posterior surface (fades posterior). FIG. 183. Orbiculus ciliaris, Annulus ciliaris Chorioidea ! i Iris (facies anterior) MM Margo ciliaris - (iridis) Annulus iridis major / / fcupilla Circulus iridis minor 'Annulus iridis minor The iris ("rainbow") of a clear gray eye, with the adjacent part of the sclerotic coat. Seen from in front. (After Toldt, Anat. Atlas, Wien, 1903, 3 Aufl., p. 896, Fig. 1347.) (e) Greater ring of iris (annulus iridis major), between iris and corpus ciliare. (/) Lesser ring of iris (annulus iridis minor), between ciliary zone (zona ciliaris} and pupillary zone (zona pupillaris} of iris. (g) Folds of iris (plicae iridis). (h) Pupil (pupilla). (i) Sphincter muscle of pupil (M. sphincter pupillae). (j) Stroma of iris (stroma iridis) . (k) Dilator muscle of pupil (M. dilator pupillae). (1) Pectinate ("comb-like") ligament of iris (Lig. pectinatum iridis) (0. T. pillars of the iris). Observe the relation of the fibres of this ligament to those of Descemet's lamina. (m) Spaces of Fontana at the angle of the iris (spatia anguli iridis [Fon- tanae]). DISSECTION OF THE HEAD AND NECK 381 (n) Greater arterial circle (circulus arteriosus major), (o) Lesser arterial circle (circulus arteriosus minor). What is the pupillary membrane (membrana pupillaris) of foetal life? The ciliary nerves and ciliary arteries and the Vv. vorticosae should now be reviewed. (See pp. 277-281.) Examine espe- cially, at the back part of the eye, between the chorioid and the sclera, the passage of the Vv. vorticosae into the sclera; cut through these and observe the Aa. ciliares posteriores breves coming from the sclera to the chorioid. Layer of Pigment (Stratum pigment!) . In an eyeball which has had its sclera and cornea removed and is under water, remove the chorioidea piecemeal, so as to expose the stratum pigmenti and the retina. Note that the stratum pigmenti is divisible into three parts : (a) Pigment layer of retina (stratum pigmenti retinae). (b) Pigment layer of ciliary body (stratum pigmenti corporis ciliaris). (c) Pigment layer of iris (stratum pigmenti iridis). Retina. In this study the following : (a) Optic part of retina (pars optica retinae). (aa) Serrated edge (ora serrata). (b) Ciliary part of retina (pars ciliaris retinae). (c) Papilla of optic nerve (papilla N. optici). (d) Excavation of papilla of optic nerve (excavatio papillae N. optici). (e) Yellow spot (macula lutea). Present in man, but not in the ox or sheep. (/) Central fovea (fovea centralis). (g) Blood-vessels of the retina (vasa sanguinea retinae). (Fig. 184.) The blood-vessels of the retina may now be studied. The student should sometime control this study by an examination of the eye-ground of a living person through the ophthalmoscope. Note— (a) Superior arteriole [venule] of temporal retina (arteriola [venula] temporalis retinae superior). (b) Inferior arteriole [venule] of temporal retina (arteriola [venula] temporalis retinae inferior). (c) Superior arteriole [venule] of nasal retina (arteriola [venula] nasalis retinae superior). (d) Inferior arteriole [venule] of nasal retina (arteriola [venula] nasalis retinae inferior). 382 LABORATORY MANUAL OF HUMAN ANATOMY (e) Superior macular arteriole [venule] (arteriola [venula] macularis superior). FIG. 184. Arteriola and venula temporalis retinae superior Arteriola and venula nasalis retinae superior Arteriola and venula retinae medialis Arteriola and venula nasalis retinae inferior Arteriola and venula temporalis retinae inferior Papilla N. optici Fovea centralis of the macula lutea Venula macularis superior Venula macularis inferior The fundus of the eye. with the retinal vessels ; in the left normal eye of a dark-haired young man, as seen with the ophthalmoscope. Erect image. (After E. v. Jager, in Toldt, Anat. Atlas, Wien, 1903, 3 Aufl., p. 898, Fig. 1355.) (f) Inferior macular arteriole [venule] (arteriola [venula] macularis inferior). (g) Medial arteriole [venule] of retina (arteriola [venula] retinae me- dialis). Vitreous Body (Corpus vitreum). In an eyeball no longer fresh, one that has been kept for from one to four days, divide the tunicae of the eye at the equator, reflect the cut edges backward and forward, and, as Anderson Stuart has suggested, allow the " eye-kernel" (corpus vitreum + lens crystallina) to slip out into a vessel filled with clean water. Transfer it for a few minutes to a strong solution of picrocarmin, then wash in water. The membrana hyaloidea, capsula lentis, and zonula ciliaris [Zinni] will be stained red, and their connections are easily visible. In the vitreous body study — (a) Hyaloid canal (canalis hyaloideus) (0. T. canal of Stilling). (b) Hyaloid fossa (fossa hyaloidea) (0. T. fossa patellaris). (c) Hyaloid membrane (membrana hyaloidea). (d) Vitreous stroma (stroma vitreum). (e) Vitreous humor (humor vitreus). DISSECTION OF THE HEAD AND NECK 383 Where does the hyaloid artery (A. hyaloidea) run in the embryo ? Ciliary Zonule (Zonula ciliaris [Zinni]). (See Figs. 179 and 180.) How is this formed? What is its relation to the corpus vit- reum and to the lens? What part of it is known as the " sus- pensory ligament of the lens"? Study— (a) Zonular fibres (fibrae zonulares). (b) Zonular spaces (spatia zonularia) (0. T. canal of Petit). The well-known saccular appearance of these spaces may be easily produced if the point of a fine blow-pipe be inserted into them and they be inflated with air. FIG. 185. Facies anterior.. _^B mk - Facies posterior Polus anterior-'""!!!;" """ T polus posterior ''•Axis lentis Aequator lentiscT „ The terms used for the orientation of the lens. (After Toldt, Anat. Atlas, Wien, 1903, 3 Aufl., p. 900, Fig. 1363.) Crystalline Lens (Lens crystallina). Cut through the fibrae zonulares of the zonula ciliaris [Zinni] and remove the lens. Examine the following : (a) Capsule of lens (capsula lentis). (b) Anterior pole of lens (polus anterior lentis}. (c) Posterior pole of lens (polus posterior lentis). (d) Anterior surface of lens (fades anterior lentis). (e) Posterior surface of lens (fades posterior lentis). (f) Axis of lens (axis lentis). (g) Equator of lens (aequator lentis) (0. T. circumference). (h) Radii of lens (radii lentis). Now divide the anterior part of the capsula lentis with a sharp knife and press the lens out through the opening. Study the stained capsule as it floats in water. Press the substance of the lens (substantia lentis) between the finger and thumb, and 384 LABORATORY MANUAL OF HUMAN ANATOMY note that the cortical substance (substantial corticalis) is soft while the central part or nucleus of the lens (nucleus lentis) is firmer. Place a bit of the lens in thirty-three and one-third per cent, alcohol for twenty-four hours, then tease it apart and under the microscope examine — (a) Epithelium of lens (epithelium lentis). (b) Fibres of lens (fibrae lentis). Chambers of Eyeball (Camerae oculi). These are two in number : (a) Anterior chamber of eyeball (camera oculi anterior). (aa) Angle of iris (angulus iridis) (0. T. iridocorneal angle). Why is this of great importance ? (6) Posterior chamber of eyeball (camera oculi posterior). Study the form, position, and boundaries of each. Both con- tain the so-called aqueous humor. ORGAN OF HEARING (ORGAN ON AUDITUS). This consists of several parts, viz. : (a) Internal ear (awn's interna). (aa) Membranous labyrinth (labyrinthus membranaceus) . (ab) Osseous labyrinth (labyrinthus osseus). (b) Middle ear. (ba) Cavity of tympanum (cavum tympani). (bb) Eustachian tube (tuba auditiva [Eustachii]). (be) Mastoid cells (cellulae mastoideae). (c) External ear (auricula) (0. T. pinna). The dry temporal bone should be thoroughly reviewed in con- nection with the study of the organ of hearing. The external ear has been studied already. (Cf. p. 258.) Take a temporal bone, preferably one with the auricula still attached. to it; saw off the squama temporalis by making a horizontal cut at the level of the root of the zygomatic process ; remove roof and anterior wall of the external acoustic meatus piecemeal, with the aid of bone-forceps and chisel, until the mem- brane of the tympanum is exposed. DISSECTION OF THE HEAD AND NECK 385 External Acoustic Meatus (Meatus acusticus externus). Examine the external acoustic meatus (meatus acusticus ex- ternus) thus opened, and compare it with a dry temporal bone, and if possible with a macerated specimen showing the carti- laginous part well. Study— (a) External acoustic porus (porus acusticus externus). (b) Tympanic incisure (incisura tympanica [Eivini}). (c) Cartilaginous external acoustic meatus (meatus acusticus externus cartilagineus) . (d) Cartilage of acoustic meatus (cartilago meatus acustici). (da) Notches in cartilage of external meatus (incisurae cartilagi- nis meatus acustici externi [Santorini]). (db) Layer of tragus (lamina tragi). FIG. 186. Incus Canalis semicircularis lateralis Canalis semicircularis superior Vestibulum labyrinthi / Basis stapedis / Apertura vestibularis cochleae Area vestibula- ris superior .Grista trans- Meatus acus- ticus exter- nus s Tractusspiralisforaminosus Cochlea (scala tympani) Lamina spirnlis (ossea and membranacea ) I Jlulbus V. jugularis supcric Membrana tympani Cavum tymp'an'i Nearly frontal section through the outer, middle, and inner ear. (After Toldt, Anat. Atlas, Wien, 1903, 3 Aufl., p. 932, Fig. 1447.) Cavity of Tympanum (Cavum tympani). This cavity (cavum tympani) should next be studied. Make an opening through the roof of the tympanum (tegmen tympani) just lateral from the eminentia arcuata (due to the superior semicircular canal) and about one centimetre in front of the angulus superior pyramidis. The opening leads into the tym- panic antrum of the mastoid wall of the cavity of the tympanum. Enlarge the opening carefully with bone-forceps, gradually re- moving piece by piece the whole roof or tegmental wall (paries 25 386 LABORATORY MANUAL OF HUMAN ANATOMY tegmentalis). Note that the epitympanic recess (recessus epi- tympanicus} is opened into; observe its cupolar portion (pars cupularis). The general shape of the cavity and walls of the tympanum may easily be remembered by thinking of a miniature cigar-box obliquely placed inside the temporal bone. Study the following : (a) Jugular wall (paries jugularis) (0. T. floor). (ab) Styloid prominence (prominentia styloidea). (b) Mastoid wall (paries mastoidea) (0. T. posterior wall). (ba) Tympanic antrum (antrum tympanicum) (0. T. mastoidal antrum). (bb) Prominence of lateral semicircular canal (prominentia canalis semicircularis lateralis). (be) Prominence of facial canal (prominentia canalis facialis). (bd) Pyramidal eminence (eminentia pyramidalis). (be) Fossa of incus (fossa incudis). (bf) Posterior sinus (sinus posterior). (bg) Tympanic aperture of canaliculus of chorda (apertura tym- panica canaliculi chordae). (c) Carotid wall (paries carotica) (0. T. anterior wall). FIG. 187. Prominentia canalis semicircularis lateralis Eminentia pyramidalis, Fenestra vestibuli i Processus cochleariformis Semicanalis M. tensoris tympani ' Semicanalis tubae auditivae \ Antrum tympanicum Canal for the M. stapedius Canalis caroticw .Margo occipitalis Canalis facialis (FaUoppii) •^Cellulae mas- toideae Sulcus promontorii • ; \ Cavum tympani / Promontorium i Fossula fenestrae cochlea^ Incisura mastoidea The medial wall, paries labyrinthicus, of the left bony tympanic cavity, and the mastoid cells, cettulae mastoideae, shown in a section through the mastoid process and the anterior part of the petrous part of the temporal bone. Seen from the anterior and lateral side. (After Toldt, Anat. Atlas, Wien, 1903, 3 Aufl., p. 927, Fig. 1432.) (d) Labyrinthic wall (paries labyrinthicus) (0. T. inner wall). (Fig. 187.) (da) Fenestra ("window") of vestibule (fenestra vestibuli) (0. T. fenestra ovalis). (daa) Fossula of fenestra of vestibule (fossula fenestrae vestibuli). (db) Promontory (promontorium) . DISSECTION OF THE HEAD AND NECK 387 (dba) Sulcus of promontory (sulcus promontorii). (dbb) Subiculum ("support") of promontory (subiculum promontorii). (dc) Sinus of tympanum (sinus tympani). (dd) Fenestra ("window") of cochlea (fenestra cochleae] (0. T. fenestra rotunda). (dda) Fossula of fenestra of cochlea (fossula fenestrae cochleae). (ddb) Crest of fenestra of cochlea (crista fenestrae coch- leae). (de) Cochleariform process (processus cochleariformis). Observe the mastoid cells (cellulae mastoideae) and the tympanic cells (cellulae tympanicae}. (e) Membranous wall (paries membranaceus) (0. T. outer wall). This consists largely of the membrane of the tympanum, which should now be studied. FIG. 188. Margo occipitalis- Sulcus sigmoideus~ Cellulae mastoideae 'Membrane and proc- esses in the re- cessus epitympani- cus and in the an- trum tympanicum Cms longum incudis Manubrium mallei Membrana tympani Pars tympanica ossis temporaUs ** Canalis facialis (Fattoppii) ^Processus styloideus Processus mastoideus The lateral wall, paries membranaceus, of the left tympanic cavity, and the entrance to the mastoid cells. The antrum tympanicum contains branching connective -tissue strands. Seen from the medial side. (After Toldt, Anat. Atlas, Wien, 1903, 3 AufL, p. 927, Fig. 1433.) Membrane of the Tympanum (Membrana tympani) (O. T. Drum- head). (Figs. 186, 188, and 191-193.) Examine — (a) Flaccid part (pars flaccida) (0. T. Shrapnell's membrane). (b) Tense part (pars tensa). (c) Border of membrane of tympanum (limbus membranae tympani). (d) Anterior malleolar fold (plica malleolaris anterior). (e) Posterior malleolar fold (plica malleolaris posterior). These two folds are sometimes called " Prussak's striae." (/) Malleolar prominence (prominentia malleolaris). (g) Malleolar stria (stria malleolaris). (h) Umbo ("prominent part") of tympanic membrane (umbo mem- branae tympani). (i) Cutaneous layer (stratum cutaneum). 388 LABORATORY MANUAL OF HUMAN ANATOMY (j) Fibrocartilaginous ring (annulus fibrocartilagineus) . (k) Radiate layer (stratum radiatum). (1) Circular layer (stratum circulare). (m) Mucous layer (stratum mucosum). Tympanic Mucous Membrane. This membrane (tunica mucosa tympanica) presents a num- ber of folds and recesses. Examine— FIG. 189. M. tensor tympani Tuba Memb. tymp. aitdi- Meatus acusticus externus tiva The cavum tympani and membrana tympani. A part of the meatus acusticus externus and the tuba auditiva are seen from in front, and somewhat from above and the side. (From Gegenbaur, Lehrb. der Anat. des Mensch., Leipzig, 1899, 7 Aufl., Bd. II. p. 619, Fig. 730.) (a) Posterior malleolar fold (plica malleolaris posterior). (b) Anterior malleolar fold (plica malleolaris anterior). (c) Anterior recess of membrane of tympanum (recessus membranae tympani anterior). (d) Superior recess of membrane of tympanum (recessus membranae tympani superior). (e) Posterior recess of membrane of tympanum (recessus membranae tympani posterior). (f) Fold of anvil (plica incudis). (g) Fold of stirrup (plica stapedis). (h) Secondary membrane of tympanum (membrana tympani secundaria). Are any tympanic glands (Gl. tympanicae) visible? Auditory Ossicles. These small bones (ossicula auditus) are three in number,— stirrup (stapes], anvil (incus), and hammer (malleus). In the stapes study— (a) Head of stirrup (capitulum stapedis). (b) Anterior limb (crus anterius). DISSECTION OF THE HEAD AND NECK 389 (c) Posterior limb (cms posterius}. (d) Base of stirrup (basis stapedis) (0. T. foot-piece). Incisura tympanica (Rivini) Pars flaccida membra nae tympani Plica membranae tympani anterior Spina tympanica major ^^ Fissura pctroti/mpanica (Glaseri) Prominentia malleolaris Limbus membranae tympani Stria malleolaris^ Umbo membranae tympani FIG. 190. ^nr V£:$|L Plica membranae tympani posterior Spina tympanica, minor Meatus auditorius externus Limbus membranae tympani : — .Pars tensa membranae tympani '~ Oanalis fadalis (Fattoppii) The lateral surface of the left tympanic membrane (suface towards the meatus acusticus externus; the latter has been removed by a saw-cut parallel and close to the tympanic membrane). (After Toldt. Anat. Atlas, Wien, 1903, 3 Aufl., p. 924, Fig. 1420.) In the incus study— (a) Body (corpus incudis). (b) Long limb (crus longum). (ba) Lenticular process (processus lenticularis) . (c) Short limb (crus breve). FIG. 191. Plica malleolaris anterior Chorda tympani Lig. mallei superius — Recessus epitympanicus - rapitulum mallei ' Plica malleolaris posterior. Recessus membranae tympani' posterior Recessus membranae tympani anterior ^Tubaauditiva » --—Insertion of the M. tensor tympani -Manubrium mallei Membrana tympani Canalis facial is (Fattoppii)' Opening of the recessus membranae tympani superior The medial surface and the anterior and posterior recesses of the tympanic membrane, brought into view by a saw-cut through the tympanum close to and parallel to the membrane and by removal of the anvil. (After Toldt, Anat. Atlas, Wien, 1903, 3 Aufl., p. 924, Fig. 1421.) In the malleus study— (a) Handle of hammer (manubrium mallei). (b) Head of hammer (capitulum mallei}. 390 LABORATORY MANUAL OF HUMAN ANATOMY (c) Neck of hammer (collum mallei). (d) Lateral process (processus lateralis) (0. T. processus brevis). (e) Anterior process (processus anterior [Folii]) (0. T. processus gra- cilis). Joints and Ligaments of the Auditory Ossicles, Study the following: Joints (Articulationes ossiculorum auditus). (a) Joint between anvil and hammer (articulatio incudomalleolaris) . (b) Joint between anvil and stirrup (articulatio incudostapedia) . (c) Junction of stirrup and tympanum (syndesmosis tympanosta- pedia). FIG. 192. Posterior wall of the apex of the recess (fold of mucous membrane) Apex of the recess / Lig. mallei superius. Capitulum mallei in longitudinal ^ section Plica incudis Cms longum incudis,. Insertion of the M. tensor. tympani Processus lenticularis - Manubrium mallei Stratum mucosum'' Substantia propria-'" Membrana tympani Annulus fibro- cartilagineus Sulcus tympanicus/ Recessus epitympanicus .Lig. mallei laterale £•,__ Recessus membranae tympani superior '~*~ -•— Pars flaccida membranae tympani ~"~--Prominentia malleolaris : Umbo membranae tympani ~^-Meatus auditorius extern us -—Stratum cutaneum of the drum membrane Frontal section of the left tympanic membrane and of the adjacent part of the external auditory passage, meatus acusticus externus, made after hardening in chromic acid and alcohol and decalcifica- tion with hydrochloric acid. The section passes through the head of the malleus and in front of the manubrium mallei. Seen from in front. (After Toldt, Anat. Atlas, Wien, 1903, 3 Aufl., p. 925, Fig. 1423.) Ligaments (Ligg. ossiculorum auditus). (a) Anterior ligament of hammer (Lig. mallei anterius). (b) Superior ligament of hammer (Lig. mallei superius). (c) Lateral ligament of hammer (Lig. mallei laterale) (0. T. external ligament). (d) Superior ligament of anvil (Lig. incudis superius). (e) Posterior ligament of anvil (Lig. incudis posterius). (f) Obturator membrane of stirrup (membrana obturatoria [sta- pedis]). (g) Annular ligament of base of stirrup (Lig. annulare baseos sta- pedis). I Basis stapedis DISSECTION OF THE HEAD AND NECK 391 (h) Fixing- muscle of the base of the stapes (M. fixator baseos sta- pedis). Muscles of Auditory Bones. These muscles (musculi ossiculorum auditus) are two in number : (a) Tensor muscle of tympanum (M. tensor tympani). (b) Stapedius muscle (M. stapedius). Study form, position, origin, insertion, action, and innerva- tion of each. FIG. 193. Capitulum mallei, ^^^^^^ 'St" ^Ak Crus breve Spina tympanica minor-|» WJft f Incudis Processus anterior