i '; BIOLOGY v UBRARY G THE DUBLIN DISSECTOR, OR SYSTEM OF PRACTICAL ANATOMY. ROBERT HARRISON, M.D., M.R.I.A., KF.LLOW OF THE ROYAL COLLEGE OF SURGEONS IK IRELAND, AND OF ENGLAND; 980B 01 ANATOMY AND SIRGERY IN THE UNIVERSITY OF DT.T.LIX AHD ..\E OF THE .SURGEONS OF THE .TEKVIS- STREET INFIRMARY, ETC.. ETC. Centjj WITH ONE HUNDRED AND SIXTY ILLUSTRATIONS. VOL. I. DUBLIN: KAN NIX AND CO., GRAFTON-STRE KT, >1 M.F.RS TO THE ROYAL COLLEGE OF SURGEONS IN IRELAND. 'LONDON : LONG.MAN AND co. ; MA< f,A< HI A\ AND CO. H- Y-l BIOLOGY LIBRARY G PREFACE. IN presenting a new Edition of the Dublin Dissector, or System of Practical Anatomy, I have to express my satisfaction at the favourable reception the former edi- tions of this work have met with for many years. Since its first appearance, in the year 1827, several editions have appeared, each containing some additions and improvements. The last having been for some time out of print, my Publishers have urgently requested me to prepare this edition, the completion of which has been unavoidably delayed by numerous other avoca- tions. Since the first appearance of this work numerous Manuals of Anatomy have been published in these as well as in other countries, some of which have been arranged very much after the same plan, others in a more systematic form. In the present edition I have adhered very closely to that arrangement, which, being founded on practical experience, I originally adopted from a conviction of its being well suited to the improvement of the anatomical student : subsequent experience has confirmed this im- pression. The science, however, has of late years been A2 180289 iv PREFACE. so extended that the chief difficulty I have experienced has been to condense into a reasonable and convenient compass all the important parts of such a very extensive and varied subject. I have not abridged any portions of the former editions, but have added to, and altered most ; I have also corrected many errors and inaccuracies which escaped my observation in the original. I have in- troduced much new matter, particularly on General or Structural Anatomy, also on the Nervous System and on the Organs of Sense. The whole work has been revised with much care, and may indeed be said to have been re- written ; and I trust it will be found to contain a tolerably correct and complete, though condensed, view of the most important details of human descriptive anatomy. I have also, in the present edition, illustrated the descriptions by numerous Engravings, according to the plan now so generally adopted by writers on anatomy, as well as on other descriptive or demonstrative sciences.' For the selection, arrangement, and descriptions of the wood-cuts I am indebted to Dr. John Hill, late Demon- strator of Anatomy in the Park-street School of Medi- cine, Avho has devoted much time and trouble to this task. Many of the cuts are from original drawings by Mr. Du Noyer, and a considerable number are reduced copies, by that artist, of engravings in the standard works of the present day. In the preparation of this work, the great object I have always held in view has been to direct the student in the manner best adapted to facilitate his inquiries ; in the descriptive details, therefore, I have prefaced each with directions as to the best mode of displaying the anatomy of each region, and have then directed attention to those parts most useful in a practical, or most interesting in a physiological, point of view. The many additions to the present work have in- creased it to such a size that I have deemed it advisable to divide the whole into two volumes or parts, an arrangement which cannot, I think, be found in any way inconvenient, as each part contains distinct and independent subjects, and a copious Index of the entire is annexed to each volume. I may take this opportunity of presenting my acknow- ledgments to numerous writers to whom I have referred, and from whom I have quoted in the following pages. I have also to offer my sincere thanks to my friends, Dr. Hill, for his exertions in respect to the wood-cuts, and Drs. Hatchell and King for their trouble in revis- ing and correcting the Press. ROBERT HARRISON. 1, Hume-street, Dublin. CONTENTS. VOLUME I. PART I. OF THE MUSCLES, VISCERA, ETC. CHAPTER. PAGE. I. ANATOMY OF THE EXTERNAL, PARTS OF THE HKAD AND FACE, 1 External Parts of the Head, .... ib. General Remarks on Muscles of the Head, 2 Division of, ib. Superficial Muscles of the Head, ib. Occipito-frontalis Epicranial Aponeurosis, .... ib. Vessels and Nerves of Scalp, 3 Structure, Pathology, &c., of Scalp, 4 External Muscles of Ear, ib. External Parts of the Face, 5 Division of Muscles of, 6 Orbicularis Palpebrarum, ib. Physiology, &c., of ditto, 7 Tensor tarsi, or Homer's Muscle, 8 Muscles of the Nose, Lips, &c , ib. Buccinator Muscle, 11 Physiology, &c, of Facial Muscles, 12 Division of Glands in general, ib. Peculiarities of Salivary Glands, 13 Parotid Gland Steno's Duct, 14 Socia Parotidis, ib. Vessels and Nerves of Parotidean Region, 15 Pathology of Parotid Gland, 16 M.ivseter Muscle, ib. Teraporalis Muscle Temporal Aponuurosis 17 I'tcrygoid Muscles, 19 Motions of lower Jaw, 20 ta ami Nerves of the Face, 21 V1H CONTENTS. CHAPTER. PAGE. II. ANATOMY OF THE NECK, 24 The Muscles of the Neck, ib. General Remarks, 25 Platysma-myoides Musculus Risorius Santorini, . . 26 Cervical Fasciae, 27 Pre vertebral Fascia, 28 Sterno-cleido-mastoid Muscle, ib. Division of Neck into triangular Regions, 29 Sterno-hyoid, Sterno-thyroid, and Omo-hyoid Muscles, 31 Thyroid Body. Levator Glandule, 32 Physiology and Pathology of Thyroid Body, .... 33 Digastric Muscle, ib. Digastric Region, 34 Submaxillary Gland, ib. Whartonian Duct, 35 Pathology of Submaxillary Gland, ib. Mylo-hyoid and Genio-hyoid Muscles, ib. Sublingual Space, 36 Sublingual Gland, ib. Hyo-glossus and Genio-hyo-glossus Muscles, .... 37 Lingualis Muscle, 38 Styloid Muscles, ib. Vessels and Nerves of the Neck, 39 Mouth, 42 Tongue, 43 Pathology of Tongue, 44 Pharynx, 45 Constrictors of Pharynx, 46 Openings in Pharynx, 49 Palate, Arches of; Uvula, 50 Levator Palati and Tensor Palati Muscles 51 Motor Uvulae, Palato-glossus, &c., 52 Tonsil or Amygdala, ib. Deglutition, three Stages of, 53 Pathology of soft Palate, Tonsils, &c., 55 (Esophagus, 56 Pathology of Pharynx and (Esophagus, ib. Larynx, 57 Os Hyoides, ib. Cartilages of Larynx, 58 Ligaments of Larynx, 61 Muscles of Larynx, 63 Openings of Larynx, 67 Vessels and Nerves of Larynx, 68 Pathology of Laiynx and Trachea, 70 Deep Muscles of the Neck, 71 Longns Colli, Recti Capitis antici, &c., 72 ( oNTKNTS. lx CHAPTER. PAGE. III. ANATOMY OF THE THORAX, 74 Muscles on anterior and lateral parts of Thorax, . . ib. Mammary Gland, ib. Pathology of ditto, 77 Pectoralis Major, . . . . ib. Pectoralis Minor, &c., 79 Serratus Magnus, 80 Intercostal Muscles, 82 Levatores Costarum, Triangularis Sterni, ib. Axilla, 83 Vessels and Nerves of Axilla, 84 Cavity of the Thorax, 85 Mode of opening Thorax, 86 Anterior Mediastinum, ib. Pleurae, 87 Ligamentum latum Pulmonis, 89 Middle Mediastinum, 90 Posterior Mediastinum, Vena Azygos, Thoracic Duct, &c. &c., ib. Lungs, 92 Roots of the Lungs, 93 Structure of the Liings, 94 Pathology of Pleurae and Lungs, 97 Parts passing through upper Orifice of Thorax, ... 98 Trachea, 99 Bronchial Glands, ib. Bronchial Tubes, 102 Pericardium, ib. Openings in fibrous Layer of Pericardium, 100 Pathology of Pericardium, 107 Heart, ib. Pulmonary Artery, 115 Ductus Arteriosus, 116 Aorta, 120 Endocarde, 121 Vessels and Nerves of Heart, ib. Muscular Tissue of Heart, 124 Sounds of Heart, 131 Pathology of Heart, 132 IV. MrscLES ON THE POSTERIOR PART OF THE TRUNK, . 134 Muscles of the Back Ligamentum Nucha?, .... 134 Cervical A poneurosis Lumbar Fascia, 135 Trapezius, 137 Lalissimiis Dorsi, 138 lihomboid, minor and major 139 I.evator Anguli Scapula? Sorrati Post id 140 X CONTENTS. CHAPTER. PAGE. IV. MUSCLES ON THE POSTERIOR PART OF THE TRUNK con- tinued, Splenius Colli Splenius Capitis, 141 Sacro-lumbalis, Longissimus Dorsi, Spinalis Uorsi, Cer- vicalis Descendens, &c. &c., 143 Recti Postici and obliqui Capitis, 145 V. ANATOMY OF THE UPPER EXTREMITY, 148 Muscles of the Shoulder and Arm, ib. Supra and infraspinous Fascia?, ib. Subscapular Fascia Brachial Aponeurosis, .... 149 Superficial Veins of the Arm, ib. Deltoid Muscle, 150 Supraspinatus, 151 Infraspinatus Teres Minor, 152 Subscapular Muscle, 153 Remarks on Capsular Muscles of the Shoulder Joint, . 154 Teres Major Muscle, ib. Coraco-brachialis and Biceps Muscles, 154 Semilunar Fascia, 156 Brachialis Anticus, or Externus, 157 Triceps Extensor Cubiti, ib. Vessels and Nerves of the Arm, 159 Forearm and Hand, 160 Subcutaneous Bursae, ib. Superficial Veins Basilic, Cephalic, Median, . . . 161 Cutaneous Nerves, ib. Fascia of Forearm Annular Ligaments, 162 Palmar Fascia, 163 Palmaris Brevis Muscle, 164 Arrangement of the Muscles of Forearm, ib. Pronators and Flexors, 165 Supinators and Extensors, 170 Muscles of the Hand, 175 Vessels and Nerves of the Forearm and Hand, ... 181 VI. ANATOMY OF THE ABDOMEN AND PELVIS, 184 Muscles on anterior and lateral Parts of Abdomen, . ib. Superficial Fascia of Abdomen, ib. Scarpa's Fascia, Camper's Fascia, . 185 General Observations on the Abdominal Muscles, . . 186 Obliquus Externus, 188 Linea Alba, 189 Umbilicus, Linear semilunares, 190 Linea? Transverse, external inguinal or abdominal Ring, 191 Intercolumnar Fascia Spermatic or Cremaster Fascia. 1 l> - 2 t'ONTKN I-. XI CHAPTER. PAGE. VI. ANATOMY OF THE ABDOMEN AND PELVIS continued. Poupart's orFallopius' Ligament, or Crural Arch, . . 192 Gimbernaut's Ligament, 193 Triangular Ligament or Colles's Fascia, 194 Obliquus internus, ib. Conjoined Tendons, 195 Cremaster Muscle, ib. Transversalis, 196 Posterior Tendon of Transversalis, Fascia Lumborum, 198 Rectus, 200 Line* transverse, 201 Pyramidalis Muscle, 202 Fascia transversalis, 203 Internal inguinal or abdominal King, 205 Infundibuliform Fascia, ib. Tunica Vaginalis of the Cord, 206 Spermatic or inguinal Canal, ib. Hernia, 207 Oblique inguinal Hernia, ib. Coverings of oblique inguinal Hernia, ib. Direct or ventro-inguinal Hernia, 209 Coverings of direct Hernia, 210 Internal direct Hernia ; external direct, ..... ib. Crural Septum ; Inguinal Pouches, 212 Epigastric Artery ; Circumflex Ilii Artery, 213 Femoral or Crural Hernia, 214 Inguinal Region, 215 Inguinal Glands, Sapheua Vein, 216 Fascia Lata, ib. Cribriform Fascia ; Hey 's Ligament, 217 Internal Surface of Crural Arch, 219 Fascia propria, ib. Fascia iliaca, 220 Parts which occupy the Crural Arch, 222 Femoral or Crural" Ring, 223 Crural Sheath, ib. Coverings of Femoral Hernia, 224 Measurement of Parts engaged in Hernia, 225 Viscera of the Abdomen, 226 Regions of the Abdomen, ib. External Surface of the Peritonaeum, 228 Internal Surface, ib. Anatomy of the Peritonaeum, 229 Omenta, Mesocolons, &c. &c , 234 Division of Viscera of Abdomen, 238 Digestive Apparatus, ib. Stomach, 240 XIV CONTENTS. CHAPTER. PAGE. VIII. ANATOMY OF THE INFERIOR EXTREMITY continued. Fascia Lata, 362 Muscles on the Forepart and Sides of the Thigh, . . 364 Tensor Vaginae Femoris, ib. Sartorius, 365 Rectus Femoris, Vasti, Triceps Adductor, &c. &c., . . 366 Vessels and Nerves of the Thigh, 371 Anatomy of the posterior Part of the Thigh, 373 Muscles of the Hip, 374 Glutseus Maximus, Medius, &c., ib. Pyriformis, Gemelli, Obturator internus, externus, &c., 376 Glutoeal and Sciatic Vessels, &c., 379 Sciatic Nerve, &c., 380 Muscles on the back Part of the Thigh, ib. Hamstring Muscles, ib. Poplitaeal Space, 382 The Leg, 383 Fascia ; Subcutaneous Veins and Nerves, 384 Plantar Fascia, 385 Muscles on the anterior and external Part of the Leg, ib. Tibialis Anticus, Extensor Digitorum Longus, &c. &c., 386 Extensor Digitorum Brevis, 388 Peroneus Longus and Brevis, ib. Anterior tibial Vessels and Nerves, 389 Muscles on the Back of the Leg, 390 Gastrocnemius, Plantaris, Solaeus, &c. &c , ib. Muscles of the Foot, 396 Posterior tibial Vessels and Nerves, . . , 402 TABLE OF ILLUSTRATIONS. VOLUME I. FIG. PAGE. 1. Muscles of the Head and Face, 3 2. Pterygoid Muscles, 19 3. Muscles of the Neck, superficial layer, 25 4. Muscles of the Neck, 30 5. Styloid Muscles and Muscles of the Tongue, 37 6. Cavity of the Mouth, 42 7. Muscles of the inferior region of the Tongue, ..... 44 8. Muscles of the Pharynx ; posterior view, 45 9. Muscles of the Pharynx ; lateral view, 47 10. The Pharynx, laid open from behind, 48 11. Muscles of the soft Palate, 55 12. Cartilages of the Larynx ; lateral view, 58 13. Cartilages of the Larynx ; posterior view, 59 14. The Larynx ; vertical section, 60 15. The Rima Glottidis, .- 62 16. Muscles of the Larynx ; lateral view, 64 17. Muscles of the Larynx ; posterior view, ib. 18. Muscles of the Neck ; deep layer, 71 19. Muscles of the anterior aspect of the Trunk, 78 20. Muscles of the Thorax and Neck ; lateral view, .... 81 21. Viscera of the Thorax, 85 22. Transverse section of the Thorax, shewing the relations of the Pleurae, 88 23. The Heart and Roots of the Lungs ; anterior view, ... 94 24. The Trachea and Bronchial Tubes laid open, . . . . 95 25. Muscles of the posterior aspect of the Trunk, 136 26. Muscles of the Back ; second and third layer, .... 139 27. Muscles of the Back ; deep layer, 142 28. Muscles of the Shoulder, . * 151 29. Muscles of the Arm ; anterior view, 153 30. Muscles of the Arm ; posterior view, 157 31. Muscles of the anterior aspect of the Forearm ; superficial laver, . 164 XVI TABLE OF ILLUSTRATIONS. FIG. PAGE. 32. Muscles of the anterior aspect of the Forearm ; deep layer, 168 33. Muscles of the posterior aspect of the Forearm ; superficial layer, 170 34. Muscles of the posterior aspect of the Forearm ; deep layer, 173 35. Muscles of the Hand, 176 36. Muscles of the anterior aspect of the Abdomen, . . . . 187 37. Transverse Section of the Abdomen, 197 38. The Inguinal Region in the Male ; shewing the Anatomy of Inguinal Hernia, 204 39. The Coverings of a scrotal Hernia, 208 40. The Abdominal Kings and Crural Arch in the Female, . . 215 41. Transverse Section of the Abdomen and Pelvis, shewing the posterior Surface of the anterior Wall of the Abdomen, the Relations of the pel vie Viscera, &c., 218 42. The anterior Surface of the Abdomen divided into Regions, 227 43. The Reflections of the Peritonaeum, 230 44. Trans verse Section of the Abdomen, shewing the relations of the Peritonaeum, 232 45. The Alimentary Canal, from the (Esophagus to the Rec- tum, 239 46. The termination of the Ileum, and the commencement of the large Intestine 250 47. The Liver ; its superior and inferior surfaces, .... 273 48. Section of the Kidney, 284 49. Diaphragm ; thoracic surface, 291 50. Diaphragm ; inferior or abdominal surface, 292 51. Muscles of the Perinaeum, 304 52. Section of the Pelvis of the Male, shewing the Viscera in situ, 315 53. Transverse Section of the Pelvis, shewing the arrangement of the Fasciae, 323 54. The Urinary Bladder and Urethra laid open, 328 55. Section of the Testicle, 334 56. Section of the Pelvis of the Female, shewing the Viscera in situ, 350 5 7 . Muscles of the anterior aspect of the Trunk and Extremities, 360 58. Muscles of the Forepart and Sides of the Thigh, .... 365 59. Muscles of the posterior aspect of the Thigh and Leg, . . 372 60. Muscles of the Hip, 374 61. Muscles of the anterior and external part of the Leg, . . 386 62. Muscles of the Back of the Leg ; deep layer, . . . .- . 393 63. Muscles of the Sole of the Foot; first layer, 396 64. Muscles of the Sole of the Foot ; second layer, 398 65. Muscles of the Sole of the Foot ; third and fourth layers, . 399 THE DUBLIN DISSECTOR. CHAPTER I. DISSECTION OF THE EXTERNAL PARTS OF THE HEAD AND FACE. SECTION I. EXTERNAL PARTS OF THE HEAD. Tin: integuments (commonly called the scalp) covering the cranium are firm and dense, although when felt they give the sensation of being thin : the cuticle is delicate and scaly, but the cuds is very thick, and furnished with many sebaceous follicles. The subjacent cellular membrane contains gmndated fat, and the bulbs of the hairs, which afterwards perforate the skin in an oblique direction. This tissue is condensed and lamellated, having somewhat a ligamentous stnicture, and adheres so intimately to the subjacent muscular and tendinous expansion, that the inexperienced student may find some difficulty in exposing the surface of the latter. Both this and the skin differ in structure hi different situations ; hi the anterior third or fourth, or the frontal region, which is bald, and around which the hairs terminate in an abrupt line, as also around the ears, the cutis is delicate, and the cellular tissue is loose and contains less adeps ; posteriorly they are more dense, vascular, and adherent, and perfect baldness seldom occurs ; the hairs are stronger, they do not end abruptly, but continue soft and down-like for some distance along the neck : this part of the scalp is often found in the dead body congested with serous and sanguineous effusion, owing to the gravitation of the fluids after death. Make an incision through the integuments along the median line, from the tuberosity of the occipital bone, as far forwards as the lower part of the forehead ; from each extremity of this, make a transverse incision about three inches long ; let the posterior one be parallel to the Z DUBLIN DISSECTOR. superior transverse ridge of the occipital bone, and the anterior one parallel, and about half an inch superior to the eyebrow ; cautiously dissect off the integuments from the subjacent muscular and tendinous expansion, which is the occipito-frontalis. This muscle, like most of the superficial muscles of the face, is closely attached to the skin, which circumstance, added to the paleness and smallness of their fibres, ren- ders their dissection somewhat difficult and tedious ; there is no deep or dense fascia covering these muscles, as in other regions of the body. Most of the superficial muscles of the head and face, during life, assist some of the organs of sense, and contribute to produce certain changes in the countenance, indicative of character or passion, and expressive of many diseases, tetanus, peritonitis, &c. In point of function, they may be considered as belonging to the class of mixed muscles, that is, they are in part voluntary and in part involuntary : with the excep- tion of the aponeurosis of the occipito-frontalis, the tendon of the orbicularis palpebrarum, and that of the corrugator supercilii, there is no perfect tendinous structure in the other muscles of this class. The superficial muscles of the head are divided into those of the cranium aadrfaco.,, 1'hcse of the cranium are the occipito-frontalis, and the time common iiuiscles of the ear : to these some add the cor- rngatores supeiviliorum ; th'e^e, however, I prefer placing among the inus'4;s^of'-the, face. , GcciPiTO-FiiOis TA'HS is itie only muscle which properly belongs to the scalp ; it is a thin, broad, digastric, or rather quadriceps muscle, fleshy at each extremity, aponeurotic in the centre. It is often so pale, weak, and thin, as to be difficult of dissection ; the occipital por- tions are less adherent to the skin and more distinct than the frontal ; its tendinous expansion is stronger and more apparent before and behind than superiorly or laterally. It arises on each side by tendi- nous and fleshy fibres, from the two external thirds of the superior transverse ridge of the occipital bone, and from the external and pos- terior part of the mastoid process ; the fibres on each side ascend from behind forwards and from without inwards, and soon terminate in one thin and broad tendon, which extends over the upper and lateral parts of the cranium This epicranial aponeurosis having arrived opposite the coronal suture, ends in two convex fleshy portions, broader and thicker, but paler, than the posterior extremities of the miiscle ; these anterior portions, which are thicker externally than internally, de- scend over the frontal bone, and are inserted, fleshy on each side, into the integument of the eyebrow, mixing with the fibres of the corrugator supercilii and orbicularis palpebrarum muscles : a small fleshy slip is often continued down along the nasal bones, and is at- tached to the internal angular process of the os frontis, and infcriorly to the nasal bones or cartilages : this sh'p is described by some as a distinct muscle, under the name of pyramidalis nasi, or fronto-nasalis. Use. The occipito-frontalis muscle can raise the eyebrows and inte- guments of the forehead into transverse wrinkles, draw the eyebrows a little outwards, and make tense the skin of the upper eyelids, and thus .-xposcthe eyeball, as in staring: it can also pull tin- scalp backwards; but if the eyebrows bo depressed and lixed, this muscle can then (particularly in some persons) draw the scalp downwards and for- wards. This muscle is very closely connected to the scalp, particu- Fig. 1.* larly in front, but loosely to the cranium, it can thus move easily on the latter, carrying with it the former, which it also serves to support in apposition with the cranium, so as to prevent the skin slipping or yielding- when any weight, is pressed against the head. Its origin is connected Avith the sterno-mastoid, the trapezius, and splenius muscles, and its insertion with those of the eyebrows. Some describe the occipito-frontalis, not as one, but as four distinct muscles, two on each side, under the names of the occipital and frontal muscles of each side, and consider the cranial aponeurosis as their common in- sertion. Several vessels and nerves perforate this muscle, and ramify on its surface and in the integument, viz., anteriorly, the supra-orbital branches of the ophthalmic nerve and artery ; laterally, the temporal ' * The muscles of the head and face. 1. The occipital portion of the occipito- frontalis muscle. 2. Its frontal portion. 3. The epicranial aponeiu-osis. 4. The superior auris, or attollens aurem. 5. The anterior aims, or attrahens anrem. C. The posterior auris, or retrahens aurem. 7. The temporal aponeurosis. 8. The orbicularis palpebrannn, which conceals the cormgator supercilii and tensor tarsi. 9. The pyramidalis nasi. 10. The compressor nasi. 11. The le- vator labii superioris alajque nasi. li>. The zygomaticus minor. 13. The zy- gomaticus major. 14. The levator labii superioris proprius,- apart of the levator angnli oris is seen between the muscles I-.' and 13. 16. The depressor labii inferioris. 17. The orbicularis oris. 18. The buccinator, lit. The mas- ^ter. -2(i. The zygomatic arch. 21. The mastoid procc--. B2 4 DUBLIN DISSECTOR. and posterior auris arteries, with branches of the pbrtio dura and infe- rior maxillary nerves ; and posteriorly, the occipital arteries spread their tortuous branches upwards and fonvards, accompanied by the occipital nerves, branches of the second cervical nerve. It covers from behind fonvards, the occipital, temporal, parietal, and frontal bones, also the upper portion of each temporal aponeurosis, the corrugator supercilii muscle, and the supra-orbital nerves and vessels. The cra- nial or epicranial aponeurosis is composed of tendinous fibres which are distinct, glistening, and parallel behind, but anteriorly, superiorly, and laterally become weak, greyish, and interlaced like cellular tis- sue, and frequently deficient in spots. The integuments in this region are highly organized, being supplied with numerous nerves and vessels ; these are derived from different and distant sources, and are chiefly destined to nourish the hair bulbs hi the cellular tissue : in the line of the sutures they have frequent inos- culations with the vessels of the diploe, and of the dura mater. This high organization of the scalp is not only of anatomical but of practical importance, as it serves to explain many of the pathological phenomena which are of ordinary occurrence in this region ; thus, it is frequently the seat of encysted tumours, horny growths, &c. ; these often appear to arise in the sebaceous follicles, the ducts of which have be- come obstructed from irritation or injury ; a vitiated secretion then accumulates in the sac, which sometimes becomes circularly enlarged, and at others the contents slowly escaping from the ducts, and hardening, assume horny and various other appearances. The scalp is a common seat of erysipelas, both idiopathic and symptomatic. Injuries of it are of very frequent occurrence, and are more serious than those of the same extent in other situations. Incised wounds bleed more freely ; punctured wounds are very frequently followed by high inflammatory symptoms, local and general, in consequence of matter being confined under the tense epicranial aponeurosis, which, in such cases, will re- quire free division. The compact density of the cellular tissue explains the hard rim which surrounds the ecchymosis, the effect of contu- sion. In the foetus the scalp is very thin, and the aponeurosis is loosely attached to the pericranium by reticular membrane ; this, and not the subcutaneous cellular tissue, is the seat of those large ecchymoses so commonly seen after parturition, and which in general are quickly removed by the absorbent system : at this age, too, the pericranium is very vascular, and except along the sutures is easily raised from the bones, numerous red dots indicating the ruptured bloodvessels. The common muscles of the ear are three in number, viz., superior, anterior, and posterior auris : SUPERIOR AURIS, or ATTOLLENS AUREM, is a small, thin, triangu- lar muscle, situated on the temple and above the ear, arising broad and tendinous from the cranial aponeurosis, where it covers the tem- poral fascia on the side of the cranium, just above the external ear ; the fibres descend converging, become fleshy, and are inserted into the IH'ULIX DISSECTOR. 5 upper and anterior part of the cartilage of the car. Use, to raise the cartilage, and deepen the ineatus of the ear, also to make tense the epicruniul fascia. This muscle is between the skin and temporal fascia, its anterior edge is confounded with the following muscle. AMKKIOK Anns, or ATTRAHKXS AUREM, is connected with the la-t, i> of the same form, but smaller, and often indistinct; it arises from the posterior part of the zygomatic process, and from the cranial aponeurosis, passes backwards and downwards, and is inserted into the anterior part of the helix. Use, to draw the external ear forwards and upwards. This muscle is superficial, and lies on the temporal fascia, vessels, and nerves ; its lower edge is lost in the cellular tissue. POSTERIOR AURIS, or RETRAHEXS AUREM, often consists of two or three distinct fasciculi, it is the strongest of these auricular muscles ; it lias no connexion to the epicranial fascia, but arises from the mas- toid process above the sterno-mastoid muscle, passes forwards, and is inserted into the back part of the concha. Use, to enlarge the meatns of the ear and direct it backwards. This muscle . is covered only by the skin, it lies iipon the temporal bone. In addition to these muscles, which move the external ear, there are several small muscles attached to different parts of the cartilages, which serve to alter their form, and expand their cavities; these muscles, as also those in the tympanum, shall be described hereafter in the dissection of the organ of hearing.* SECTION II. DISSECTION OF THE EXTERNAL PARTS OF THE FACE. THE muscles of the face require careful dissection ; they are delicate, and often very pale ; they may be classed into the superficial and deep : the former into those of the eyelids, nose, and mouth, being the dilators and constrictors of these openings ; the latter into those of the lower jaw and palate. Make an incision around the base of the orbit, through the skin, which is here very fine, and closely adhering to the fibres of the orbicularis muscle ; next make a perpendicular incision, along the middle line of the nose, to the centre of the upper lip, conti- nue this in a semicircular manner round the angle of the mouth to the middle of the lower lip, and thence to the chin, and lastly from the chin to the angle of the jaw ; reflect the integuments cautiously from the eyelids and side of the face, as far back as the ear, avoiding the slender muscular fibres which adhere to the skin, and the vessels and nerves which will be exposed in this dissection. * Previous to, or immediately after dissecting the muscles of the face, the student .should examine the brain, the description of which organ will be found at the head of the nervous system. DUBLIN D1SSECTOK. The integuments of the face are generally soft, delicate, and highly organized with vessels, nerves, and follicles ; the vascularity is emi- nent in the lips and cheeks ; hair, soft and downy, covers the greater portion, particularly in man ; in the latter also the beard and whiskers, which are of variable extent and strength, require a corresponding organization in the cellular tissue : in the eyelids, the latter is loose and reticular, always free from adeps, but prone to serous infiltration ; both skin and cellular tissue are more dense in the median line than laterally, especially on the nose and lip : adipose substance surrounds most of the muscles and abounds in the young, and at all ages, be- tween the masseter and buccinator muscles. The superficial muscles of the face may be considered as thirty- three in number, that is sixteen pair and one azygos, and are arranged as follows. Three pair belong to the palpebrce, viz. : orbicularis palpebrarum, tensor tarsi, and corrugator supercilii, (the levator palpebrse is deep seated in the orbit, and is arranged among the muscles of that region). Four pair belong to the nose, viz., pyramidalis nasi, levator labii superioris alaeque nasi, compressor and depressor naris. Three pair belong to the upper lip, viz., levator labii superioris, levator anguli oris, and depressor labii superioris. Three pair belong to the lower lip, viz., depressor anguli oris, de- pressor labii inferioris, and levator labii inferioris. Three pair belong to the mouth, viz., zygomaticus major, minor, and buccinator, and one azygos, the orbicularis oris ; writers vary this ar- rangement, but no material difference exists. ORBICULARIS PALPEBRARUM, or SPHINCTER OCULI, broad and thin, somewhat oval, in some subjects very pale and indistinct, in others strong and well marked, it adheres to the skin, surrounds the base of the orbit, covers the eyelids, and occupies a great portion of the face ; it arises by several fleshy fibres from the internal angular process of the os frontis, and from the upper edge of a small horizontal tendon (which tendon, TENDO OCULI, or TENDO PALPEBRARUM, nearly one quarter of an inch in length, is inserted internally into the upper end of the nasal process of the superior maxillary bone, thence passes out- wards and backwards to the internal commissure of the eyelids, where it forks into two slips which enclose the caruncula lachrymalis, and are inserted each into the tarsal cartilage, and the lachrymal duct) ; the fleshy fibres then proceed in curves, upwards and outwards along the upper edge of the orbit, the eyelid and tarsal cartilage, as far as the temple and external commissure of the eyelids ; thence the fibres curve in a similar manner along the inferior eyelid and edge of the orbit to the internal canthus, where they are inserted into the nasal process of the superior maxilla, into the inferior edge of the hori- zon tul tendon, and into the inner third of the lower edge of the orbit. Use, to close the eyelids, chiefly by depressing the superior, the leva- lor muscle of which it directly opposes: it also serves to press the tears inwards towards the puncta lachrymalia ; the superior orbital fibres 01 BLIX DISSECTOR. 7 c'an depress tlu- eyebrow and aid the corrugator supercilii in drawing- it, as well as tin' eyelids, inwards, and oppose the occipito-frontalis and shade tlu- eye : (In- interior fibres can raise the cheek, raise and draw the lower eyelid inwards, and compress the lachrymal sac, wliich they eo\vr. In sk-ep it is principally relaxed, and the eye is covered chiefly by the descent of the upper palpebra, its elevator muscle being also relaxed : when awake its contraction covers the globe, not only by bringing down the upper, but also by elevating the lower eyelid, hence the " equator oculi," the line formed by the approximated tarsi, is lower during real than in feigned sleep; in the former, also, the cor- nea is seldom entirely covered, as it always is in the latter. This muscle is covered by and adheres to the skin ; superiorly it overlaps and intermixes with the occipito-frontalis, and covers the corrugator supercilii, the temporal fascia, the frontal vessels and nerves, the tarsal cartilage and ligament, and the levator palpebra? superioris ; inferiorly it intermixes with the muscles of the cheek and lips, and sometimes with the platysma myoides, it covers the malar bone, the inferior tarsus and its ligament, the origin of the levator anguli oris, levator labii superioris, and the infra-orbital vessels and nerves. The external or orbital fibres of this muscle are strong and red, and run circularly round the base of the orbit ; the middle orpal- pebral fibres are pale, thin, and scattered, and are contained in the eyelids ; the internal or ciliary portion is a thick but pale fasciculus, situated under the cilia?, at the edge of each eyelid. The palpebral and ciliary portions adhere more closely to the skin, and present an elliptical appearance, as the fibres from the upper and lower eyelid intersect each other at the outer canthus, and adhere to the ligament of the external commissure. The horizontal tendon of this muscle passes across the lachrymal sac a little above its centre, and is a little twisted ; a strong aponeurosis derived from its upper and lower edge, covers all the anterior surface of the sac, and adheres to the margins of the bony gutter, in which it is lodged, where it becomes continuous with the periosteum. This tendon can be seen or felt through the integuments during life, particularly when the muscle is in action, or wlu-n the eyelids are drawn towards the temple. Both in structure and function this muscle belongs to the mixed class; the external, circular or orbital fibres are red, strong, and voluntary, and act very powerfully, as when we endeavour to screen the eye from too bright a light, while the inner portions of the muscle are relaxed, or only in slight action, whereas these latter fibres are weak, pale, and scattered, and essentially involuntary, and act in winking, while the orbital fibres are relaxed ; during sleep also these fibres, like other sphincters, are in a state of gentle or tonic contrac- tility. It sympathises with the eye hi a remarkable and most useful manner ; it possesses great irritability, particularly in children ; in purulent and strumous ophthalmia it is frequently spasmodically con- tracted, and totally prevents the eye being seen ; this affection is 8 DUBLIN DISSECTOR. somewhat analogous to the spasmodic constriction of the sphincter ani muscle. In the operation of opening the lachrymal sac, the incision should commence immediately below this tendon, so as to avoid injuring it, and be carried obliquely downwards and outwards, to the extent of about half an inch. Separate the orbicularis from the occipito-frontalis over the internal half of the superciliary arch, the tensor tarsi and the corrugator su- percih'i muscles will be exposed. TENSOR TARSI arises tendinous from the posterior edge of the os unguis, where it joins the os planum, passes forwards between the conjunctiva and the expansion of the tendo oculi which covers the lachrymal sac, divides into two portions, which are inserted into the la- chrymal ducts, along which the fibres extend, nearly as far as the puncta. Use, to draw the puncta and eyelids into close contact with the eye, also to press the puncta towards the nose, to compress the lachrymal sac, and to force out the secretion from the follicles of the caruncula lachrymalis. This muscle is also named HORNER'S muscle, from its discoverer ; it will be better seen if the two tarsi be divided about their middle, and their inner portions turned towards the nose without injuring the tendo oculi. CORRUGATOR SUPERCILII arises fleshy and tendinous from the internal angular process of the os frontis, passes upwards and out- wards, and is inserted into the middle of the eyebrow, mixing with the orbicularis and occipito-frontalis muscles. Use, to depress and approximate the eyebrows, throwing the skin of the forehead into ver- tical wrinkles, as in the act of frowning ; this pair of muscles is vo- luntary, but they cannot act separately ; they directly oppose the occipito-frontalis and shade the eye. They are covered by the orbi- cularis and occipito-frontalis, and lie on the os frontis and on the fron- tal nerve and vessels. PYRAMIDALIS NASI, superficial, long, thin, often wanting, arises from the occipito-frontalis, descends close to its fellow between the brows, covering the nasal bones and sutures, becomes broad and aponeurotic, and is inserted into the compressor nasi muscle. Use, it raises the skin covering the ossa nasi, when the occipito-frontalis is in action, but if the latter be relaxed, it can then draw down the inner end of the eyebrow. COMPRESSOR NASI is thin and triangular, placed on the side of the nose, between the skin and the cartilage ; it arises from the inner side of the canine fossa, in the superior maxilla ; the fibres pass for- wards, expanding over the ala nasi, and are inserted by a thin apo- neurosis into the dorsum of the nose, joining some fibres from the opposite side. Use, to press the ala toward the septum, or to draw it from it, so that it may alternately enlarge or diminish the anterior naris ; its action will partly depend on the form of the cartilage ; if convex, it may compress, if concave it may expand the ala nasi ; in DfBLIX DISSECTOR. 9 cliflicult inspiration it appears in a state of increased action, and is then a dilator more than a compressor, at the same time raising the upper lip, but when inhaling odours it alternately expands and compresses the ala ; in tetanus it permanently dilates it. The insertion of this muscle is connected with the occipito-frontalis, and pyrarnidalis, and its ori- gin with the following, which partly covers it. LEVATOR LABII SUPERIORIS ALJEQUE NASI is long, thin, and triangular, placed on the side of the nose, between the orbit and the upper h'p ; it arises by two origins ; first, from the upper extremity of the nasal process of the superior maxilla ; second, broad, from the edge of the orbit, above the infra-orbital hole; the fibres descend and converge a little, and are inserted into the ala nasi, and into the upper lip and orbicularis oris rmiscle : its name denotes its use. The supe- rior and orbital origins of this muscle are covered by the orbicularis palpebrarum ; the inferior portion is superficial ; the angular vein and artery separate its origins : the orbital head covers the infra-orbital nerve and vessels, the levator anguli, and some of the orbicularis oris muscles.* ZYGOMATICUS MINOR is very small, and sometimes wanting ; it arises from the upper part of the malar bone, passes downwards and forwards, and is inserted into the upper lip near the commissure, unit- ing with the other muscles which are inserted there. C/se, to draw the angle of the mouth upwards and outwards, as in smiling ; it lies su- perior, and parallel to the major, between which, and the levator labii, it is inserted. ZYGOMATICUS MAJOR is long and narrow, and inferior to the last ; arises tendinous and fleshy from the lower part of the malar bone, near the zygomatic suture : it descends obliquely forwards, and is in- serted into the angle of the mouth. Use, to draw the corner of the mouth upwards and backwards. The zygomatic muscles are partly concealed at their origin by the orbicularis palpebrarum ; their in- sertion intermingles with the levator, depressor anguli, and orbicularis oris muscles ; they lie on the malar bone, and cross the masseter and buccinator muscles, also the labial vein and artery, and they run su- perficial and superior to the duct of the parotid gland ; they are im- bedded in much soft adipose substance. LEVATOR AXGULI ORIS (musculus caninus) is situated about the middle of the face, behind and a h'ttle external to the orbital portion of the levator labii superioris alaeque nasi, or the levator labii of some ; arises from the canine fossa in the superior maxillary bone, immediately * The external or orbital head of this muscle is described by most writers as a distinct muscle, and has been enumerated by me as such ; it is called Levator Labii Svperiorit : as, however, it will be found on dissection to be inseparably connected with the levator labii alseque nasi, I prefer describing it as part of the outer head of that muscle ; in like manner I have united the depressor labii sitjH'rioris or incisor, and the deiiressor nan's, which are by some described as distinct muscles; much variety will be found in the number and structure of the muscles in the nasal and labial regions ; this accounts for the different ex- pression of the corresponding features during life, as also for the different de- scriptions given of these muscles by different authors. 10 DUBLIN DISSECTOR. below the infra-orbital foramen, and above the alveolus of the first molar tooth ; it descends obliquely forwards and outwards, and is in- serted narrow into the commissure of the lips and into the orbicularis oris ; its name denotes its use. This muscle is covered by the orbicu- laris palpebrarum, levator labii superioris alaeque nasi, zygomatic muscles, and by a quantity of soft adeps, also by the infra-orbital nerve and vessels, which ramify upon its surface and separate it from the orbital portion of the levator labii alaeque nasi : it lies on the superior maxilla, the buccinator muscle, and the mucous mem- brane of the mouth. DEPRESSOR LABII SUPERIORIS AL^QUE NASI, a small flat muscle, very variable as to size and structure, exposed by everting the upper lip, and raising the mucous membrane on the side of its fraenum ; it arises from the myrtiform fossa in front of the alveoli of the canine and incisor teeth of the superior maxilla, ascends obliquely forwards, and is inserted into the integuments of the upper lip and into the fibro-cartilage of the septum and ala nasi. Use, to press the Up against the anterior teeth and even to draw it under these, also to depress the septum and ala nasi. It is covered by the levator labii, orbicularis oris, and mucous membrane, and it lies upon the bone. DEPRESSOR ANGULI, vel TRIANGULAKIS ORIS, flat and triangular, apex above, situated at the lower part of the face ; arises broad and fleshy from the external oblique line on the outer side of the lower jaw, which extends from the anterior edge of the masseter muscle to the mental foramen ; the fibres ascend converging, and are inserted narrow into the commissure of the lips, where the fibres are con- tinuous or mingled with the orbicularis, zygomatic, and levator anguli muscles : its name denotes its use. This muscle is covered by the skin, some of its fibres are continuous with those of the platysma myoides ; it overlaps the buccinator and the following muscle. The facial artery bounds its external edge and separates it from the nias- seter. DEPRESSOR LABII INFERIORIS, vel QUADRATUS MENTI, broad and somewhat square, arises from the side and front of the lower maxilla, just above its basis, internal to the last, and continues as far forwards as the middle line ; the fleshy fibres, intermixed with fat, ascend a little inwards, decussating with some of the opposite muscle, and are inserted into half of the lower lip and into the orbicularis oris ; its name denotes its use. This muscle is covered by the skin, and ex- ternally by the depressor anguli oris ; it lies on the bone, the mental nerves and vessels, orbicularis oris muscle, and mucous membrane : by separating this from the last muscle, the mental nerve and vessels are exposed ; the fibres are parallel, and many are continuous with those of the platysma ; this muscle is difficult to dissect, its inner fibres being pale and intermixed with fat, it is not unlike the structure of the tongue : it conceals the following muscle. LEVATOR LABII INFEUIORIS, vel MENTI, is best exposed by turn- ing down the upper lip, and raising the mucous membrane by the l>t I'.I.IN mss|:<'TOR. 1 I side of the fra-mim : drives from the alveoli of the incisor teeth of the lower maxilla, by the side of the symphysis : the tibres diverge as tliev descend obli<|iiely forwards between the mucous membrane and the depressor labii iut'erioris : inserted into the integument of the chin. T'-s-r. to elevate the chin and lower lip : this muscle is analogous to the deprosor of the upper lip. It assists iu forming the prominence of the chin. Our.icrLAms, vel SPHINCTER ORIS, surrounds the opening of the mouth ; consists of two fleshy fasciculi, one for either Up, placed be- tween the skin and mucous membrane, and constituting the chief thickness of the lip ; these fasciculi decussate each other at the com- missures, and intermix with all the dilating muscles inserted there. Use, to approximate the lips and regulate their motions in the acts of speaking and breathing, and to oppose the actions of the several mus- cles which are inserted into the commissures ; it can also close the lips with different degrees of force, as in the process of suction, mastica- tion, and deglutition. This muscle has no bony attachment; its tibres are blended with fat, particularly on their cutaneous surface ; internally they are more smooth and distinct ; they adhere most closely to the skin, and throw it into numerous minute ruga? when they contract. BUCCINATOR is broad, tlu'n, and somewhat square ; situated between the two alveolar arches, it forms the inner side of the cheek, and the lateral boundary of the mouth, and lies close to the mucous mem- brane of the latter ; arises posteriorly from the two last alveoli of the superior maxilla, as far back as the pterygoid process, from the ex- ternal .surface of the posterior alveoli of the lower maxilla, as far back as the coronoid process, and form a strong aponeurosis, named the ptcrygo or intermaxillary ligament (which extends from the extremity of the internal pterygoid plate and tuberosity of the superior max- illary bone, to the root of the coronoid process, and which affords attachment to the superior constrictor of the pharynx posteriorly and to the buccinator anteriorly). From these three origins the fibres pass forwards, at lirst horizontally, but then converge, and the superior and inferior decussate, and are inserted into the commissure of the lips, where the}' intermix with those of the orbicularis and of the other muscles at the angle of the mouth. Use, to press the cheek against the teeth, so as to bruise and push the food between them, and to di- minish the cavity of the mouth, as in mastication and deglutition ; it is also much engaged in the articulation of certain expressions, as well as in filling wind instruments; it can also retract the commis- sure of the lips. The buccinator is covered, even in thin subjects, by a considerable quantity of fat, which separates it from the coronoid proem of the lower maxilla, and from the insertion of the temporal muscle (this fat extends in the form of large, soft, round masses be- neath the masseter muscle) ; it is also covered by the zygomatic, the depressor anguli oris and platysma muscles, and by the facial vessels; several branches of the facial artery and vein, and of the seventh and 12 DUBLIN DISSECTOR. fifth pairs of nerves, ramify on its surface ; it lies on the mucous membrane and on a number of small round mucous glands called buccal ; it is perforated near its superior posterior third by the duct of the parotid gland, opposite the lower edge of the second or third superior molar tooth, a strong fascia is continued from the outer coat of this vessel over the muscle. The group of superficial muscles now described present peculiari- ties, both as to structure and function, when contrasted with those in other regions ; the orbicularis oris has no bony attachment ; all the other facial muscles have one extremity only inserted into bone or periosteum, and that in a very feeble manner, the other being attached to skin or subcutaneous or submucous tissue, or to some other mus- cle ; they have little or no tendon in their structure ; their fibres are weak, soft, and loosely connected to each other, without investing sheath or fascia ; their general development is very variable, and bears no ratio in strength and colour to that of the general voluntary mus- cular system. They present many characters hi common with the mixed class ; the will has not perfect control over them, and they occasionally assist in respiration without its influence ; nervous and mental emotions, health and disease, pleasure and pain, affect them in a well known and remarkable manner ; by their habitual action they cause certain folds or lines in the skin, more or less permanent, which give rise to peculiar expressions of the countenance, indicative of cor- responding feeling and passion, and thus lay the foundation for the study of physiognomy. A cheerful, joyous state of mind being for the most part denoted by an expansion and elevation of all the fea- tures, effected by the combined actions of the occipito-frontalis and of the elevators of the lips, and of their commissure ; while in the opposite condition, that of sadness, sorrow, or deep thought, the countenance is rather elongated, and the features depressed by the corrugators of the eyebrows, and by the depressors of the lips and commissure, aided also by the platysma myoides, which latter, though arranged among the cervical muscles, yet plainly intermingles by many fibres with those of the lips and cheeks, and must therefore exert considerable in- fluence in the motions of these parts, as also in the expressions of the countenance consequent thereon. The deep muscles of the face, which are connected with the lower maxilla, and which are employed in the process of mastication, arc the masseter, temporal, internal, and external pterygoid of each side : previous to dissecting these, the student should examine the situation and connexions of the parotid gland, the chief of the salivary glands. There are six salivary glands, three on each side, the parotid, sub- maxillary, and sublingual. The salivary glands, together with the lachrymal, mammary, and pancreas, are commonly called conglomerate glands, in contradistinc- tion to the absorbent, or lymphatic, or conglobate glands ; this term, however, is by no means distinct or definite, for other glands, viz., the liver and kidney, are equally conglomerate, though not so ob- DUBLIN D1SSKCTOK. 13 viously such. The general arrangement of the glandular system w<- liropo.se, is into two orders, the Absorbent and Secreting ; the absorbent, or lyntftltalic, or cISM-:TOI:. 1,5 proceeds, which after a abort course unites with the duct of Steno ; in SOUR- this duct opens distinctly into the month. The transverse artery of tin- face, and several branches of the facial nerve, accompany this vessel, and in general the artery is superior to it, while the nerves wind around it. This duct appears much larger than its calibre really is : it is formed of two coats, the external white, fibrous, and dense, commences beyond the anterior edge of the gland, and ends at the buccinator muscle ; and the internal, a fine, delicate, mucous mem- brane, is continuous with that lining the mouth : the canal is larger at the commencement and outside the buccinator than in the intervening space, or at the orifice in the mouth. The parts which pass through this gland are the external carotid artery and several of its branches, with their accompanying veins, and branches of the inferior maxillary and cervical nerves, also the plexus of the portio dura, or facial nerve. The first or most superficial of these parts is the ascendens colli nerve, or the superticialis colli or auricularis, it enters the gland near its lower border, and is lost chiefly in communicating with the portio dura ; this last-named nerve escapes from the cranium by the stylo-mastoid foramen, enters the gland at its posterior inferior part, passes forwards and up wards through it, and forms in its substance the remarkable plexus, parotidcean, or pes anserina, which crosses superficial to the external carotid artery, and then separates into its two great divisions, the superior and infe- rior ; a small portion of the gland intervenes between it and the ves- sels. The branch of the inferior maxillary nerve which traverses the gland is the temporo-auricular, which will be found between the neck of the lower jaw and the meatus auditorius, about half an inch above, but much deeper than the portio dura, with which it communicates, and for a branch of which it is sometimes mistaken. The external carotid artery will be found to enter the lower border of the gland, near its deep surface ; as it ascends it is crossed by the portio dura, and becomes much more superficial, its posterior auricular branch borders the lower and back part of the gland, the temporal ascends through it, the internal maxillary is deeply imbedded in it in its course forwards and inwards, the transverse facial artery also tra- verses it in a direction forwards, it also gives off numerous branches to the granules of the gland and to the ear. The veins corresponding to these arteries also pass through this organ ; the temporal and inter- nal maxillary, by their confluence, which is superficial to the external carotid artery, and very rarely to the portio dura also, forms the ex- ternal jugular vein, which descends through the gland and becomes superficial in the neck. Several lymphatic vessels and glands are con- nected with the parotid, particularly along its inferior border ; generally one or two small glands may be found imbedded in its substance, in front of the meatus auditorius. just where its cartilage is deficient. Now divide the parotid duct, raise off the gland from the masseter muscle, and from the ramus of the jaw, and observe its several deep- seated connexions. JO DUBLIN DISSECTOR. The deep or posterior surface of the gland is very irregular, it covers the posterior third of the masseter, also the ramus of the jaw behind which it sinks, and tills the deep excavation between this bone and the ear, envelopes the styloid process of the temporal bone and the muscles which arise from it, and touches the internal carotid artery, jugular vein, and the large nerves connected with these vessels ; it also fills the posterior part of the glenoid cavity in the temporal bone, and adheres to the capsular ligament of the maxilla, inferiorly it is wedged in between the internal pterygoid, digastric, and styloid muscles. The styloid process is in some cases so involved in this gland as to ap- pear to divide it into a superficial and a deep lobe, the latter will then be deeper than this process and in close connexion with the great cer- vical nerves and vessels : a portion of the parotid will also be found to accompany the internal maxillary artery between the ramus of the jaw and its internal lateral ligament ; this touches the inferior maxil- lary nerve, and in many instances extends into the fatty space between the two pterygoid muscles, where it swells out to a considerable size, so as to appear like a distinct lobe connected to the body of the gland by a narrow neck. The parotid gland receives its nutrient vessels from the external carotid artery and its branches ; its nerves are derived from the auri- cular branch of the fifth pair, from the cervical plexus, and from the sympathetic. The portio dura traverses it, but does not probably sup- ply it, although some of its filaments can be traced to the fibrous coat of its ducts. The parotid gland is composed of numerous small lobules, united together by cellular tissue, by branches of blood-vessels and nerves, and by the small roots of its excretory duct. A very small lobule can, by dissection and maceration, be divided into many smaller grains ; it is probable that each minute granule is essentially a small coecal pouch of a minute excretory duct ; several of these latter coalesce to form the excretory duct. The parotid gland is subject to several MOKBID changes, viz., in- flammation, or cynanche parotidaea, or parotitis, or mumps ; abscess ; hypertrophy, or scirrhous induration, which sometimes requires ex- tirpation ; scirrhus, ending in cancer ; fistula, the effect of abscess or wound of the gland or duct ; atrophy, or absorption ; this latter condition is usually caused by tumours, lymphatic or encysted, these by degrees come to occupy the position of the gland and cause its absorption. Such tumours simulate the enlarged parotid, though es- sentially different ; they admit of more easy extirpation, as they are usually surrounded by a capsule, and are not traversed by the ad- jacent nerves and vessels. Next clean the masseter muscle and the temporal aponeurosis. MASSETER The greater part of this muscle is superficial, it is thick and strong, covers the ramus and angle of the jaw, and consists of two portions, one anterior, which is the larger, the other posterior ; these decussate each other ; the anterior arises chiefly tendinous from the 17 superior maxilla where it joins the malar bone, also from the inferior edge of the latter, the fibres pass downwards and backwards and are inxi-rtfil tle>hy into the outer surface of the angle of the lower maxilla. The posterior or deep portion of the muscle arises chiefly fleshy from the edge of the malar bone and from the zygomatic arch, as far back as the glenoid cavity ; the fibres descend, some vertically, others obliquely forwards and are inserted, chiefly tendinous, into the exter- nal side of the angle and ramus of the jaw, as high as the coronoid process ; thus the two layers of this muscle are contrasted both in the direction of their fasciculi, as well as in the relative position of their tendinous and fleshy fibres. Use, if both portions of both muscles act together, they will elevate the lower jaw; if the anterior portions only of opposite sides act together, they can carry the jaw forwards and upwards ; and if the posterior alone, they can move it backwards and upwards ; if the superficial layer of one side act alone it can rotate the chin to the opposite side, and if the deep layer only act it can rotate it to its own side. Thus the masseter muscles of opposite sides, by the alternate action of their different portions, are powerful agents in mas- tication ; they not only cause the division of the food by the direct elevation and pressure of the lower maxilla against the upper, but they can also triturate it, by the great lateral motion of the jaw which their different lamina? are capable of exercising alternately. The masseter is covered by the skin, some fibres of the platysma and orbicularis palpebrarum, a portion of the parotid gland, and its excretory duct, by the transverse facial vessels and nerves, and by the zygomatic muscle. It lies on the ramus of the jaw, and conceals the insertion of the temporal, and the origin of the buccinator, from which it is sepa- rated by a great quantity of fat ; the superficial layer covers the deep one, except a small portion of the latter near the articulation of the maxilla ; strong, tendinous septa pass from the surface of this muscle through its substance, and adhere to the ramus of the bone beneath. The masseter, by its superficial layer, may assist in dislocating the lower jaw, if it suddenly contract when the chin is much depressed. This muscle, like the temporal, appears to be much under the influence of the nervous system and extremely irritable, it is very seldom in a state of paralysis, even when the superficial muscles of the face are so ; whereas in tetanus it is in a state of almost rigid contraction : in rigors also, or when exposed to much cold, these muscles evince their sym- pathy with the general system, the will loses all control over them, they act irregularly, and produce the " chattering of the teeth." TEMPORALIS is concealed by the temporal aponeurosis, the zygoma, and the masseter, it fills the temporal fossa, is thin and broad above, thick and narrow below. The aponeurosis is white and glistening, veiy strong and tense, of a semicircular form, adhering by its superior convex border to the semicircular ridge on the side of the cranium, which extends from the external angular process of the frontal along the parietal, as far back as the mastoid process of the temporal bone, and by its inferior straight margin to the upper edge of the zygoma, c 18 DUBLIN DISSECTOR. and to the superior posterior edge of the malar bone. This fascia is thin above, the muscle appears through it ; inferiorly it is thick and opaque ; it consists of tAvo laminae which are very distinct inferiorly, some fat, vessels and nerves being interposed ; the fibres composing the external layer run longitudinally, those of the internal irregularly. The temporal aponeurosis confines the muscle in its place, and gives additional origin to its fibres. Separate the masseter from its superior attachment, divide with the saw the zygoma at either end, and elevate it together with the lower part of the temporal fascia ; the temporal muscle will be thus exposed. It consists of two laminae, the super- ficial is thin, but the deep layer is very thick ; an aponeurosis or tendon is between these. It arises from all the side of the cranium beneath the semicircular ridge on the parietal bone, and from all the temporal fossa and fascia ; the fibres therefore are attached internally to the parietal, frontal, and temporal bones, also to the sphenoid as low down as the crest at the root of its great wing, which crest separates the temporal from the zygomatic fossa ; anteriorly to the malar bone, and externally to the inside of the temporal fascia, and to the zygomatic arch. The fleshy fibres all descend converging ; the middle nearly vertical ; the anterior with a little obliquity backwards ; the posterior, which are very long, pass nearly horizontally forwards, over a smooth surface at the root of the zygoma, and the inferior fibres, which arise from the' crest on the sphenoid bone, are very short, and pass trans- versely outwards. Inserted by a strong tendon into the coronoid process of the inferior maxilla ; it nearly surrounds that process, except on its outer side, and is continued along its forepart as far as the last molar tooth. Use, to raise the lower jaw when the whole muscle acts ; the anterior fibres may also advance the jaw, and the posterior long fibres can draw it backwards, while the inferior transverse fibres, which are nearly paral- lel to the external pterygoid muscle, may assist in its lateral and rota- tory motions ; this muscle, particularly its posterior portion, is the greatest security which the jaw possesses against dislocation, as it directly opposes the external pterygoid muscles which tend to advance the jaw, and to place its condyles on the zygomatic eminences. The temporal muscle is covered by the integuments, occipito-frontalis, superficial temporal vessels and nerves, temporal fascia, zygoma, mas- seter, orbicularis palpebrarum, and auricular muscles ; it lies on the side of the cranium, and covers all the bones which compose the tern poral fossa, also the deep temporal vessels, and part of the external pterygoid and buccinator muscles, from which it is separated by much fat. Wounds of the temporal aponeurosis are often attended with serious effects, the severe pain and tension interfere with the action or exten- sion of the muscle, the mouth can scarcely be opened, nor can mastica- tion be performed without great difficulty ; these symptoms simulate tetanus, from Avhich, however, they may be distinguished by attention to the countenance and to the state of the muscles of the opposite side : suppuration beneath this fascia is both troublesome and dangerous ; injury to it should be avoided in arteriotomy. In vital powers this muscle is analogous to the massi-tor. it is largely supplied with nerves from the same source. Remove the temporal, masseter, and bucci- nator muscles, also the zygomatic arch, saw or break off, low down, the coronoid process, dissect away some fat, and the pterygoid muscles will be exposed, the dissection of which maybe still further facilitated by dividing the side of the lower jaw in front of the insertion of the masseter, as the angle and rainus of the jaw can then be moved back- wards and forwards. The pterygoid muscles are situated very deep behind the ramus of the lower jaw, they are two hi number, internal and external, their names, however, only refer to their origins from the external pterygoid plate of the sphenoid bone, for neither are attached to the internal plate ; that which is called external is nearer to the median line of the body, the in- ternal is more superficial, and there- fore first met with in dissection. PTERYGOIDEUS INTERNUS is strong, thick, and somewhat quadrangular, placed on the inner side of the ramus of the jaw, parallel and very simi- lar to the superficial layer of the masseter muscle externally ; it arises tendinous and fleshy from the inner side of the external pterv- goid plate, and pterygoid process of the palate bone; it fills the greater part of the pterygoid fossa, descends obliquely outwards and backwards, and is inserted tendinous and fleshy into the inner side of the angle of the jaw, and into the rough surface above it. Use, if the muscles of opposite sides act together, to draw forwards and to elevate the jaw, thus cooperating with the superficial layers of the masseter muscles ; if alternately, they can rotate it, each moving the jaw late- rally, so as to turn it to the opposite side. This muscle is larger and longer than the external pterygoid, inferior and external to which it lies. Above, the tensor palati and superior constrictor, and below, the submaxillary gland are in contact with its internal surface : the ramus of the jaw is external to it, and separated from it by the dental nerve, the internal maxillary artery and its primary branches, which are protected from the pressure of the muscle by the internal lateral liga- ment of the jaw ; the gustatory nerve crosses it in front : the lower and posterior extremity of this muscle is very superficial, lying be- * The internal and external pterygoid muscles. The zygomatic arch and a portion of the ramus of the lower jaw have been removed. 1. The internal ptt-iy- goid. 2. The sphenoidal portion of the external ptervgoid. 3. Its ptefyeoid portion. 4. The condyle of the lower jaw. c 2 20 DUBLIN DISSECTOR. tween and in contact with the parotid and submaxillary glands : the upper extremity or origin is separated by the tendon of the tensor palati muscle from the internal pteiygoid plate, it is concealed by, and lies deeper than that of the external pteiygoid muscle. PTERYGOIDEUS EXTERNUS is short and triangular, the base at the pterygoid process, the apex at the condyle, placed at the lower part of the temporal fossa ; it arises broad and fleshy from the outer side of the external pteiygoid plate, from the crest on the root of the great wing of the sphenoid (which divides the temporal from the zygomatic fossa), and from the back part of the tuberosity of the superior max- illa ; the fibres pass outwards and backwards, horizontal, converging, and twisted, are inserted tendinous into the anterior and internal part of the neck of the lower jaw, into the interartieular cartilage and infe- rior synovial membrane. Use, when both muscles act, they draw for- ward the jaw, and at the same time the interarticular cartilages, which serve as moveable or temporary sockets to prevent the condyles slip- ping off the zygomatic eminences, when the chin is advanced, or the mouth much opened ; if the muscle of one side only act, it will draw forward the condyle of that side, and turn the chin to the opposite, and therefore when both muscles act alternately, they will become the prin- cipal agents in triturating or grinding the food. The external ptery- goid muscle lies in a transverse direction beneath the base of the cra- nium, superior to the internal pterygoid, except at its origin ; it is internal and inferior to the temporal muscle, and is also concealed by the masseter and the ramus of the jaw ; superiorly it is in contact with the sphenoid bone, posteriorly with a number of veins and with the inferior maxillary nerve at its exit from the foramen ovale, while anteriorly and inferiorly it is in contact with much adipose matter, and with the principal branches of the internal maxillary artery and inferior max- illary nerve. As the external and internal pterygoid muscles arise so near each other, and thence pass in different directions to their inser- tions, the external going transversely, and the internal descending, they leave between them a triangular space, which contains a quantity of fat, a small portion of the parotid gland, the internal maxillary artery and vein, and the dental and gustatory branches of the inferior maxillary nerve : as the internal maxillary artery is about to sink into the spheno-maxillary fossa, it sometimes passes between the origins of the external pterygoid muscle. The condyles of the jaw enjoy a slight rotation forwards and down- wards in the temporal articular cavities, they can also advance a little from the glenoid depressions, and descend so as to rest on the zygoma- tic tubercles. The lower jaw can be moved in five directions ; de- pressed, elevated, earned forwards, backwards, and rotated to either side. Depression, whereby the cavity of the mouth is opened, follows the simple relaxation of the elevator muscles, as when asleep in the erect posture ; but a greater depression, as in yawning, is effected by the platysma, digastric and hyoidaean muscles ; in opening the mouth Dllil.IN 1USSKC-TOR. 21 very wide, the upper jaw is also raised by the steruo-mastoid and di- gastric muscles. Elevation of the lower jaw is performed by the combined actions of the temporal, the masseter, and the internal ptery- goid muscles. The jaAv is moved forwards by the internal pterygoid, the anterior fibres of the temporal, the superficial layer of the masse- ter, and, above all, by the external pterygoid muscles ; if these of one side only act at a time, the cliin will not only be advanced, but turned to the opposite side. The jaw is carried backwards by the deep layer of the masseter, and particularly by the posterior portion of the tem- poral muscle. In the rotatory motions, such as occur in mastication, the chin is moved from one side to the other by those muscles which can advance and draw back the condyles acting in alternate succession on opposite sides ; during these rotatory motions, the elevators are also in slight action, and thus the food is perfectly comminuted by the pressure of the latter, and by the friction of the former against the uneven surfaces of the molar teeth. The external pterygoid muscles are the chief agents in producing dislocation of the jaw ; when the mouth is widely opened, their spas- modic action may suddenly draw the condyles and interarticular cartilages forwards off the tubercles into the zygomatic fossae. SECTION III. VESSELS AND NERVES OF THE FACE. THE arteries which are to be met with hi the dissection of tins re- gion, are the facial and the terminating branches of the external carotid ; the nerves are branches of the seventh and fifth pair. The facial artery, which is a branch of the external carotid, is seen wind- ing round the side of the jaw, anterior to the masseter, and running in a contorted course towards the commissure of the lips, and thence ascending along the side of the nose, to the internal canthus of the eye ; in this course it sends off numerous muscular branches, the co- ronary arteries of the lips, the nasal, and terminates in the angular, which communicates with the ophthalmic artery, at the inner side of the orbit. The facial artery and its divisions are accompanied by corresponding veins : the facial vein is not coiled like the artery, but is straight, and lies to its outer side; at the lower edge of the jaw it generally, but not always, divides into two branches, one superficial joins the external jugular vein, the other passing deeper in the neck joins the internal jugular. The external carotid artery, which is seen ascending from the neck into the parotid gland, gives off nume- rous branches to its several lobules, and to the ear, and a little below the condyle of the jaw divides into the transversalis faciei, temporalis su- perficialis, and maxillaris interna. The transverse artery of the face 22 DUBLIN DISSECTOR. crosses the masseter above, sometimes below the parotid duct, and divides into small muscular branches, some of which communicate wjth the facial and infra-orbital arteries. The temporal artery as- cends behind the articulation of the maxilla, on the temporal aponeu- rosis, and soon divides into an anterior and posterior branch ; the former is directed towards the forehead, supplies the integuments and muscles there, and communicates with the frontal branches of the ophthalmic artery ; the posterior division of the temporal runs tor- tuously upwards and backwards, and divides into numerous branches, which supply the integuments and inosculate with the occipital and posterior auris arteries. The internal maxillary artery is the largest branch of the carotid ; it bends in behind the neck of the lower jaw, between the bone and the internal latei'al ligament, then runs tor- tuously between the pterygoid muscles upwards, forwards, and in- wards, to the lower and back part of the orbit, where it sinks into the spheno-maxillary fossa ; in this course it sends off the middle artery of the dura mater, the inferior dental, several muscular branches to the temporal, masseter, pterygoid, and buccinator muscles, and ter- minates by dividing into the nasal, descending palatine, and infra- orbital arteries. Veins accompany these different arteries, and in the parotid gland we find the temporal and internal maxillary veins forming a plexus from which proceeds a considerable vessel called the external jugular vein, which will be afterwards seen descending su- perficially in the neck. (For the particular description of the blood- vessels of the face, see the Anatomy of the Vascular System). The nerves which are met with in the dissection of the face are branches of the seventh and fifth pair ; those of the seventh, or the portio dura, have in general a transverse direction from behind for- wards, are remarkable for their plexiform arrangement, and have nu- merous communications with the three branches of the fifth, which are distributed chiefly in a vertical direction along the anterior part of the face. The portio dura escapes from the temporal bone through the stylo-mastoid hole, and immediately gives off two or three small branches, the posterior auricular, digastric, andstylohyoid ; it then turns forwards into the parotid gland, superficial to the blood-vessels, here it divides into two large branches, the temporo-facial, and cervico- facial, which subdivide and join again by several filaments forming the plexus, named pes anserinus, or parotidcean plexus, from which pro- ceed several branches ; some ascend obliquely forwards to the temple and forehead, others pass transversely to the muscles of the face, and se- veral descend along the side of the neck, some parallel and others inferior to the side of the lower maxilla. The fifth pair of nerves consist of three portions, viz., the ophthal- mic, superior maxillary, and inferior maxillary; a branch of each of these divisions is met with in the dissection of the face. The fron- tal nerve, which is a branch of the ophthalmic, or first division of the fifth, is seen escaping from the orbit by the superciliary notch or fora- DIP, UN DISSECTOR. 23 men ; it then ascends on the forehead, distributes its branches to the inh'gmuents and muscles, and communicates with the portio dura. The infra-orbital nerve, which is a branch of the superior maxillary, or second division of the fifth, is observed passing out of the infra- orbital foramen, behind the levator labii superioris alaeque nasi, and dividing into several branches ; the most of these pass obliquely down- wards, and communicate freely with branches of the seventh pair. Through the mental foramen the mental nerve escapes : this is a branch of the inferior maxillary, or third division of the fifth pair; most of its branches ascend to the muscles of the lower lip, and several communicate with the portio dura. The temporo-auricular nerve is also a branch of the inferior maxillary, it lies deep-seated in the parotid gland, close to the meatus auditorius, to which it sends some branches, while others ascend with the temporal artery. (For the more parti- cular description of the nerves of the face, see the Anatomy of the Nervous System). The mouth, fauces, and palate, are the parts of the face next in order to be examined ; but as these are connected and continuous with the pharynx, and as this organ cannot be seen until the muscles of the neck have been removed, the student had better postpone the dissec- tion of the former until he has become acquainted with the anatomy of the latter ; we shall therefore proceed next to the dissection of the neck. 24 DUBLIN DISSECTOR. CHAPTER II. DISSECTION OF THE NECK. SECTION I. OF THE MUSCLES. THE neck implies that contracted portion of the trunk between the head and chest ; the cervical vertebrae alone forming its skeleton or support. It contains, besides the pharynx and oesophagus, larynx and trachea, numerous muscles, nerves, and vessels, whose mutual relations are complicated and intricate, but an accurate knowledge of which is of great practical importance. The neck presents a posterior, anterior, and two lateral aspects. The dissection of the posterior must be deferred, and conducted along with that of the back generally, from which it cannot be accurately separated, either superficially or still less in regard to its muscular contents ; the lateral and anterior regions may now be examined. Raise the shoulders of the subject by blocks placed beneath them, so as to make tense the muscles in this region ; divide the integuments, which are thin and delicate, near to, and in a line with the clavicle, also along the side of the jaw, from the chin to the mastoid process ; connect these incisions by another made in a perpendicular direction, in the middle line from the chin to the sternum ; dissect off the in- teguments from before backwards, in an oblique direction, from the chin towards the clavicle ; this should be done cautiously, to avoid injuring the platysma or fascia ; in the child and in the female there is generally more subcutaneous fat than in the male subject. The platysma myoides will be now fully exposed, and the sterno-mastoid and hyoid muscles partially so ; in the middle line of the neck a chain of projections maybe observed which can also be felt dxmng life, viz., a little below, but at some distance behind the chin, is the body of the os hyoides ; inferior to this is the angle of the thyroid cartilage ; next is the cricoid, below which the commencement of the trachea may be felt, on the forepart of which the soft swelling of the thyroid body can be discerned ; and lastly, the continuation of the trachea descending into the chest. The distance between the chin and ster- num, and the intervals between these several eminences, are much affected by the position of the neck from flexion to the extreme de- gree of extension. In the latter state, the space between the inferior DUlil.IN IMxviX TOR. 25 maxilla and the us hyoides, as also between the latter and the thy- roid cartilage, is greatly augmented, the trachea also is elongated and drawn upwards from the thorax : in flexion, on the contrary, the os hyoides is within the arch of the lower jaw, the cartilages of the larynx are pressed together, and but a short portion of the trachea is in this region. By altering the position of the neck, the student will soon perceive these facts, and cannot fail to conclude how much the details of any operation in the neck must be influenced by them. The muscles on the anterior part of the neck are very numerous, they are concerned in several functions and execute different motions ; some act as the ordinary muscles of locomotion, others are occasionally engaged in deglutition, and in respiration, also in the exercise of voice and speech. They are symmetrical, or similar on each side of the middle line ; they are twenty-one pair in number, and may be ar- ranged for the convenience of dissection into three layers, a superficial, middle, and deep ; the superficial consists of two pair, the platysma myoides and stemo-cleido mastoid; the middle may be divided into two orders, the superior and inferior ; the inferior are three in number, viz., sterno-hyoid, thyro-hyoid, and omo-hyoid ; the superior are nine in number, viz., digastric, mylo-hyoid, genio-hyoid; three styloid muscles, hyo-glossus, genio-hyo-glossus, and lingualis muscles ; the deep layer consists of seven pair, viz., longus colli, rectus capitis an- ticus, major and minor, rectus lateralis, and three scaleni ; this ar- rangement excludes the muscles of the palate, pharynx, and larynx. Fig. 3.* * The superficial muscles of the neck. 1. The platysma myoides. 2. The stemo- deido mastoideus. 3. Its sternal attachment. 4. Its clavicular attachment. 5. The stemo-hyoideus. 26 DUBLIN DISSECTOR. PLATYSMA-MYOIDES, or latissimus colli, is a thin and pale cuta- neous muscle, analogous to the panniculus camosus of quadrupeds ; in many subjects weak, and even indistinct ; it is situated on the fore- part and side of the neck, extending from the chest and shoulder to the face ; its figure is somewhat square, but a little longer than it is broad, and narrower in the centre than at either end ; it arises by many fine fleshy fibres from the cellular membrane, covering the upper part of the deltoid and pectoral muscles, a few also adhere to the cla- vicle ; the fibres ascend obliquely inwards ; at first loosely, afterwards closely connected to each other, and form a broad thin muscle, which covers the side and forepart of the neck; occasionally fine aponeurotic or short tendinous fibres may be noticed, prolonged into the cutis : inserted, first, into the skin and cellular tissue on the chin, decussating there with fibres from the opposite side ; second, into the fascia along the side of the lower jaw, a few only into the bone ; some fibres may be traced high on the face, and seen to join the depressor anguli oris, the zygomatic, and orbicularis palpebrarum muscles ; and third, into the fascia, which covers the parotid, and which adheres to the meatus auditorius ; some of these latter fibres take a waving transverse direc- tion towards the commissure of the lips, and constitute the musculus Risorius Santorini ; this transverse band is sometimes very strongly marked. Use, to depress the angle of the lips and the lower jaw, but if the mouth be closed it may elevate the integuments of the neck, and fold them into transverse wrinkles ; it also serves to compress and support the several muscles, glands, and vessels in this region. The platysma is covered only by the skin ; it partly conceals the cla- vicle and the deltoid and pectoral muscles, the sterno-mastoid, hyoid, and thyroid muscles ; also the digastric and stylo-hyoid, the sub- maxillary gland, the lower part of the parotid, the side of the jaw, and some of the muscles of the face ; also, in part, the external jugular vein. This vein commences in the parotid gland, descends obliquely out- wards over the sterno-mastoid muscle, where it lies very superficial, and then sinks deep behind the clavicle, and joins the subclavian vein or some of its branches. The upper portion of the external jugular vein is accompanied by a large nerve, which lies to its outer side, super- ficialis colli, a branch of the cervical plexus ascending to the parotid gland and external ear. This vein in its course down the neck receives several cutaneous veins, and almost always communicates with the internal jugular; it presents great varieties in its size and course, is sometimes double, and is sometimes even wanting. Superficial veins may also in general be marked descending along the anterior part of the neck; they arise about the os hyoides and upper part of the thy- roid body, and descend beneath some fibres of the platysma along the anterior edge of the mastoid muscle, and end in the internal or exter- nal jugular, or in the venae innominatae. The fibres of the platysma are closely connected to a layer of condensed cellular tissue, which in some subjects is very strong, and in some situations aponeurotic ; this IU 111. IN 1>!>SK( TOU. 27 is tin.- superficial cervical fascia. In some, the fibres of the platysma are so intermingled with this structure, that they cannot be perfectly separated and must be raised together. Some writers designate this as the deep cervical fascia, and apply the term superficial fascia to the subcutaneous cellular tissue, which connects and supports the fibres of the platysma, a title it does not appear to me to deserve, except in very few instances, and hi particular situations. This fascia extends over the anterior and lateral parts of the neck, is continued down over the forepart of the thorax, where it becomes cellular and adipose, ascends to the j aw, to which it is attached, expands over the parotid gland, and adlxeres to the cartilage of the ear ; in this situation its strength is greatly increased : towards the lateral and posterior parts of the neck it becomes weak like cellular membrane ; at the edge of the trapezius, one thin lamina passes superficial to this muscle, while the other stronger portion is continued beneath it to the ligamentum nuchae, giving off in this course processes to enclose the different muscles. From the posterior or deep surface of this fascia, a lamina of mem- brane is derived, which passes behind the sterno-mastoid muscle ; this is the deep cervical fascia, whose connexions are important, and may be examined in this stage of the dissection. If the superficial lamina be divided along the median line of the sterno-mastoid muscle, this deep fascia will be seen to be continuous with, or produced from, the superficial, and to pass behind the anterior border to the posterior sur- face of that muscle, so that the latter, as also the omo-hyoid, and the other muscles hi this region, may be considered as enclosed between these fasciae, each in a sort of sheath ; at the lower part of the neck it is strong, and adheres to the inter-clavicular ligament and posterior edge of the sternum and clavicles. Some loose fatty substance is here interposed between it and the superficial layer ; as the deep fascia ex- tends upwards, it covers and adheres to the sheath of the cervical ves- sels, and arriving at the space between the trapezius and mastoid muscles, it becomes, at first, weak and cellular, but inferiorly as it accompanies the great vessels beneath the clavicle it is dense, and serves to enclose the subclavian muscle, and is attached to the costo- clavicular, or coracoid ligament or membrane ; superiorly it is lost on the branches of the cervical plexus of nerves ; at the superior and lateral parts of the neck it sinks deep, behind the angle of the jaw, to which it adheres, and is connected to the styloid process of the tem- poral bone, and to the stylo-maxillary ligament, which it may be said to form ; absorbent glands, the lower part of the parotid, and much cellular membrane, here lie between these two fascise. In this situa- tion collections of matter often form, the result of cynanche parotidaea, or of inflammation of some of the lymphatic glands ; such collections are productive of great inconvenience, causing such swelling and tension, as to interfere with the motions of the jaw, and with the act of deglutition. The cervical fasciae bind down the muscles and support the vessels and glands in this region ; at the lower part of the neck they serve to protect the trachea and the upper part of the thorax 28 DUBLIN DISSECTOR. from the pressure of the atmosphere during inspiration. In the sub- sequent dissection of the deep muscles of the neck, this fascia will be found continued by lateral slips from the external sides of the sheaths of the cervical muscles to form another extensive sheath, the prevertebral fascia ; this adheres above to the occipital bone, and the adjacent mus- cles ; on either side, to the tips of the transverse processes, covers and binds down the longi colli, recti, and scaleni muscles, connected in front by loose reticular membrane to the pharynx and oasophagus, and inserted below into the first ribs, clavicles, and subclavian muscles ; it adheres to, and forms prolongations around the brachial vessels and nerves, and separates the axillae from the inferior triangular regions of the neck ; more internally it overlaps the two pleurae, and by its various inter-muscular and inter- vascular connexions with the super- ficial layers which adhere to the sternum and its ligaments, completes the cervico-thoracic septum, which, when viewed from the cavity of the thorax, appears as a vaulted partition perforated by various funnel- shaped passages for the several tubes and vessels, passing hi and out of the chest, attached to each by cellular and fibrous prolongations which are lost on their individual parietes. Dissect off the platysma and superficial fascia, and examine the subjacent muscles, the second pair of the first order. In the course of this dissection are seen branches of the cervico-facial division of the seventh pair ; many of these arch along the side of the neck towards the os hyoides and the chin, others descend to join the cutaneous branches of the cervical plexus, and they are all distributed to the platysma, fascia, and integuments. STERNO-CLEIDO MASTOIDEUS, long and flat at the extremities, but somewhat round in the centre ; placed at the anterior and lateral part of the neck ; arises by a strong flat tendon with fleshy fibres posterior to it, from the upper and anterior part of the first bone of the sternum, also by short aponeurotic and fleshy fibres from the iipper and ante- rior edge of the sternal third, sometimes half of the clavicle ; a small triangular space separates these two origins, through which small vessels and some cellular membrane pass : this space corresponds to the sterno -clavicular articulation. The sternal and longer portion of this muscle ascends obliquely backwards and outwards, and overlaps the clavicular, which ascends vertically ; about the middle of the neck they are intimately joined ; inserted by a tendon which is thick and rounded anteriorly, but thin, broad, and aponeurotic posteriorly, into the upper part of the mastoid process, and into the external third of the superior transverse ridge of the occipital bone. Use, the sternal portion can rotate the head so as turn the face towards the opposite side : the clavicular can bend the head and neck to its own side, so as to approximate the ear and shoulder ; and if the two portions of the muscle on each side act to- gether, they will move the head downwards and forwards, but if the muscles on the back of the neck be in action, so as to fix the vertebra and head, then these muscles, particularly the sternal portions, may assist in still further extending the neck, and carrying the head back- 7>1 -I5I.TX DISSECTOR. 29 wards, so as to turn the face upwards, in consequence of their insertion being posterior to the centre of motion in the occipital condyles ; this appears to be the case in tetanus : these muscles can also assist in la- borious respiration, by raising and fixing the shoulders. This muscle is covered by the integuments, platysma, superficial fascia, external jugular vein, ascending branches of the cervical plexus of nerves, descending branches of the portio dura, and by a small portion of the parotid gland ; it conceals part of the sternum and clavicle, of the sterno-hyoid, sterno-thyroid, omo-hyoid, and digastric muscles, also the lower part of the cervical vessels and several glands. The spinal accessory nerve perforates it obliquely a little above its centre, and near its posterior surface ; this nerve is a division of the eighth pair, it distributes small branches to the mastoid and trapezius muscles, and joins freely with the cervical plexus ; the spinal accessory does not always perforate, but sometimes passes posterior to the mastoid muscle ; it is supposed to associate the nerves and muscles of the neck with the respiratory system. The student may remark that the two sterno-mastoid muscles bound a large triangular space situated on the forepart of the neck, the apex at the sternum, the base at the jaw : this is divided by the mesial line into two lateral portions, which are named the anterior lateral triangles of the neck. Between the mastoid and the trapezius muscles also, on each side, a large triangular space is enclosed, the base formed by the clavicle, the apex by the mastoid process ; this space is called the posterior lateral triangle of the neck. Both these triangular regions may be observed to be subdivided into two by the omo-hyoid muscle, which crosses the neck obliquely from the shoulder to the os-hyoides. Thus on each side of the middle line four triangular spaces may be noticed, princi- pally formed by the trapezius, sterno-mastoid, and omo-hyoid muscles ; these triangles are distinguished by the terms 1. posterior inferior; 2. posterior superior ; 3. anterior inferior ; and 4. anterior superior. We do not at present allude to the important space bounded by the digastric muscle. The student should examine each of these regions, and consider the parts situated in each. These spaces can be ascertained dining life, and therefore an accurate knowledge of the contents of each may be of practical importance. 1. The posterior inferior triangle is that small space partly behind the clavicular portion of the mastoid muscle, and partly between it and the trapezius, above the clavicle and below the posterior belly of the omo-hyoid muscle ; in this space we find the trunk and several branches of the subclavian artery, vein, and the bra- chial plexus of nerves ; it is here that the operation of tying the sub- clavian artery, in case of axillary aneurism, is recommended to be performed. 2. The posterior superior triangle is above the posterior belly of the omo-hyoid, and between the mastoid and trapezius muscles; it contains the cervical plexus of nerves, several lymphatic glands, and a great quantity of cellular membrane. 3. The anterior inferior 30 DUBLIN DISSECTOR. triangle is above the sternal third of the clavicle, between the median line and anterior belly of the omo-hyoid, and rather behind the sterno- mastoid muscles ; this space contains the carotid artery, jugular vein, and accompanying nerves, also the lateral lobe of the thyroid body, all of which are covered by the sterno-niastoid, hyoid, and thyroid muscles. 4. The anterior superior triangle is between the sterno- mastoid and anterior belly of the omo-hyoid muscles ; the apex is formed by the decussation of these muscles, and is opposite the cricoid cartilage ; the base is, superiorly, marked by the digastric muscle and lingual nerve ; this space also contains the great vessels and nerves, Fig. 4.* * The muscles of the neck. 1. The mastoid process of the temporal bone. 2. The os hyoides. 3. The sterno-hyoideus muscle. 4. The sterno-thyroideus. 5. The omo-hyoideus. 6. Attachment of the omo-hyoideus to the superior costa of the scapula. 7. The thyroid body. 8. The anterior belly of the digastricus. 9. Its posterior belly. 10. Its median tendon perforating the stylo-hyoid muscle, and connected to the os hyoides by a tendinous pulley. 11. The mylo-hyoideus. 12. The genio-hyoideus. 13. The hyo-glossus. 14. 'The thyro-hyoideus. 15. The thyroid cartilage. 16. The scalenus anticus muscle. 17. The rectus capitis anticus major. 18. The levator anguli scapulae. I',). A portion of the splenius. DUBLIN DISSECTOR. 31 here, however, are only superficially covered, so that in this situation the operation of tying the carotid artery can be more easily effected. Divide the stemo-mastoid muscle about its centre, and re- flect each portion towards its attachment ; at the lower part of the neck, behind and between the sterno-mastoid muscles, are seen the following : STERXO-HYOIDEUS is long, flat, and thin, arises within the thorax from the posterior surface of the first bone of the sternum, cartilage of the first rib, sternal end of the clavicle, and sterno-clavicular capsule ; ascends obliquely inwards, approximating its fellow above, and is in- serted into the lower border of the body of the os hyoides, internal to the omo-hyoid. Use, to depress the os hyoides, pharynx, and larynx. This muscle is covered by the sternum and clavicle, by the sterno-mastoid and integuments ; it lies on the sterno-thyroid, crico-thyroid, and thyro-hyoid muscles, and on the thyroid gland and its vessels ; a tendinous h'ne often intersects it about its centre. Cut this muscle across, and reflect each portion towards its attachments, and we see the following pair of muscles : STERXO-THYROIDEUS is broader and shorter than the last, arises from the posterior surface of the sternum and cartilage of the second rib, ascends obliquely outwards, and is inserted into the obh'que line on the ala of the thyroid cartilage. Use, to depress the larynx. This muscle is covered by the sterno-mastoid and hyoid nmscles, and by the skin ; it conceals the arteria and vena innominata, the carotid and subclavian vessels, and adjacent nerves, also the thyroid body, and the trachea ; between it and the latter there is a considerable quantity of cellular membrane, wlu'ch contains several veins (inferior thyroid v.) Several filaments of the descendens noni nerve are distributed to this and to the former muscle ; it also is occasionally intersected by a ten- dinous line. It is between the sterno-thyroid muscles that the opera- tion of tracheotomy is performed, while that of laryngotomy is between the sterno-hyoid muscles, and between the thyroid and cricoid carti- lages. OMO-HYOIDEUS is long, slender, and digastric, situated obliquely along the inferior, lateral, and forepart of the neck ; it arises broad and fleshy from the superior costa of the scapula behind its semilunar notch, from the ligament covering that notch, sometimes from the base of the coracoid process, and sometimes also from the acromial end of the cla- vicle ; it ascends obliquely forwards a little above the clavicle, passes beneath the sterno-mastoid muscle, where it is generally tendinous, except in the very young subject ; becoming again fleshy, it ascends nearly vertical along the outer side of the sterno-hyoid, and is inserted fleshy into the lower border of the os hyoides, at the junction of its body and cornu, external and anterior to the insertion of the sterno- hyoid. Use (the muscle of one side cannot act independent of the other), both draw the os hyoides, pharynx, and larynx, downwards and backwards, and in deglutition serve to urge the food into the oesophagus; they also make tense the cervical fascia. The origin of 32 DUBLIN DISSECTOR. this muscle is concealed by the trapezius, it is anterior to the insertion of the levator anguti scapula?, and between the serratus magnus and supra-spinatus muscles ; the posterior belly is covered by the integu- ments and fascia, in some the clavicle overhangs it ; it divides the great posterior lateral triangle of the neck into an inferior and superior part, as was before mentioned ; this portion of the omo-hyoid can fre- quently be distinguished in the living neck. The tendon crosses the carotid arteiy and jugular vein, and is covered by the sterno-mastoid, which can thus move more easily on this structure. The anterior belly and insertion are covered by the integiiments and fascia ; this portion of the muscle divides the anterior lateral triangle of the neck into an inferior and superior part. The omo-hyoid is enclosed through its whole course between septa of the cervical fascia, it crosses over the scaleni muscles, the brachial plexus, phrenic, pneiuno- gastric and sympathetic nerves, the carotid artery, jugular vein, and superior thyroid vessels. Beneath the three last described muscles, and lying on the trachea and sides of the larynx, is a large, soft, red mass, of a crescentic shape, the concavity directed upwards ; this is the thyroid body ; it is in general larger and of a deeper colour in the child than in the adult or old, and in the female than in the male ; its size, however, varies considerably in different individuals, even of the same sex and age. It consists of two large pyramidal portions, called lateral lobes, connected together by a narrow slip, the middle lobe or isthmus ; the latter is thin and flat, and closely connected to the second, third, and fourth rings of the trachea ; the lateral lobes are plump and convex, large below, pointed above, placed by the side of the trachea and larynx, and extending as high as the alae of the thyroid cartilage ; the left lateral lobe rests on the oesophagus, and both right and left over- lap the carotid artery, inferior thyroid vessels, and recurrent nerve ; they are covered by the sterno-mastoid, hyoid, thyroid, and omo- hyoid muscles, by the platysma and skin ; they He on the side of the trachea and larynx, on the crico-thyroid and inferior constrictor of the pharynx. The middle lobe is very irregular, it is sometimes deficient, in other cases it is full and broad, and might even cause embarrass- ment in tracheotomy ; in some cases it passes behind the oesophagus, or between this tube and the trachea, a circumstance which might be productive of great inconvenience, and even danger, in the event of enlargement of this body occurring in one in whom this malformation existed. A narrow slip is often seen to ascend from the middle lobe as high as the os hyoides. A small muscular band is occasionally found to arise from its upper border, and to be inserted into the base of the os hyoides, or angle of the thyroid cartilage, named by Scemerring " levator glandula-." In the infant the lower part of the thyroid is connected to but not continuous in structure with the thymus gland. This organ has no perfect capsule, a fine cellular tissue only surrounds it ; it is of a soft and spongy texture, the cells contain a yellow, serous, and sometimes an oily fluid, it appears composed of a number IH'UUN DISSECTOK. 33 of granulations united by cellular tissue into lobules, the serous fluid is contained in the connecting cellular membrane, no excretory duct h;i< been discovered, nor does there appear to be any communication between the lobes and the lobules, except through the medium of the blood-vessels, which are of considerable si/e ; four arteries, t\vo from the carotid and two from the subclavian, are distributed to it, the for- mer border its superior margin, the latter bend along its inferior and posterior portions ; several veins issue from it, small superiorly, but very large and numerous below. This body has been by many con- sidered as glandular, and named accordingly the thyroid gland, but there does not appear anv evidence to support this opinion ; it cannot belong to the secreting glands, unless we admit that its veins (which are certainly very large) serve the additional office of excretory ducts, neither does it appear to have any peculiar connexion with the lympha- tic or absorbent system. Anatomical writers usually describe it in connexion with the larynx, but without any reason, except from its contiguity to that organ. Although it is an opinion prevalent among many physiologists, that the thyroid body is an organ for sanguifica- tion, yet it may be affirmed that its use is by no means fully ascertained. The thyroid body is very subject to enlargement, which is sometimes partial, sometimes general ; this affection is named bronchocele or goitre, and presents great varieties as to size, form, and consistence of the tumour, in some being firm and regular, in others very uneven, and soft or pulpy to the feel. Next dissect the muscles at the upper part of the neck. DIGASTKICUS, placed at the lateral and anterior part of the neck, thick and fleshy at each extremity, round and tendinous in the centre, arises from a groove in the temporal bone, internal to the mastoid process, descends obliquely forwards and inwards, ends in a round tendon which perforates the stylo-hyoid muscle, and is connected to the cornu of the os hyoides by a dense fascia, sometimes by a tendi- nous ring like a pulley ; the tendon is then reflected upwards and for- wards, and soon ends in the anterior fleshy belly, which continuing forwards and inwards, is inserted into a rough depression on the inner side of the base of the jaw, close to the symphysis. Use, to depress the lower jaw, and, when the mouth is closed, to elevate the os hyoides, tongue, and larynx ; the posterior belly can also draw these backwards and upwards, and the anterior upwards and forwards, so that this muscle can exert great influence in deglutition ; it can also draw the head backwards if the chin be fixed. The digastric is covered poste- riorly by the sterno-mastoid and splenius, and by a portion of the parotid, more anteriorly by a few fibres of the stylo-hyoideus and a small part of the submaxillary gland, by the cervical fascia, platysma, and skin ; it passes across the styloid muscles, the external and inter- nal carotid, the labial and lingual arteries, the eighth, ninth, and sympathetic nerves ; also the origin of the hyo-glossus and the inser- tion of the mylo-hyoid. In the position in which the subject is placed during this dissection, 34 DUBLIN DISSECTOR. this muscle forms the inferior or convex border of a semicircular space, the digastric region, the superior straight edge of which is marked by the side of the maxilla, and by a line continued from its angle to the mastoid process ; the skin, platysma, and cervical fascia close it in superficially, and the side of the jaw overhangs it ; its deep, or supe- rior surface is formed by the mylo-hyoid and lingual muscles, and by the side of the pharynx. This region is divided by the stylo-maxillary ligament into two spaces, the posterior or parotidaean, the anterior or submaxillary. The parotidcean space is the smaller, bounded behind by the mastoid process and meatus auditorius, and more deeply by the vaginal and styloid processes; it extends as high as the maxillary articulation ; the stylo-maxillary ligament, ramus and angle of the jaw, and internal pterygoid muscle, bound it anteriorly and separate it from the sub- maxillary space ; it is prolonged to some depth within the neck and ramus of the jaw between the pterygoid muscles ; this space contains the parotid gland, which is firmly wedged into it around the jaw, and impacted into all its irregular recesses ; also several absorbent glands, the external carotid artery and its terminal branches ; the commence- ment of the external jugular vein, the seventh nerve and its plexus, and more deeply the origin of the three styloid muscles, the internal carotid artery, internal jugular vein, and the eighth, ninth, and sym- pathetic nerves. The anterior, or submaxillary space, is larger, is bounded above by the mylo-hyoid muscle, and by the mucous membrane of the mouth reflected from the jaw to the tongue ; the muscle like a shelf divides it into a superficial and a deeper or sublingual portion, which commu- nicate around the outer border of that muscle. This space contains superficially the submaxillary and several lymphatic glands, the facial artery and vein, with their numerous branches, and the mylo-hyoid nerve of the fifth pair, and the submaxillary ganglion ; in the deeper or sublingual portion of this space, that is, above the mylo-hyoid muscle, and between it and the mucous membrane or the floor of the mouth, are contained the gustatory and lingual nerves, and more deeply still the glosso-pharyngeal ; also the Whartonian duct, the lin- gual artery and vein, with their tortuous branches, and the sublingual gland ; these last mentioned objects cannot be seen hi the present stage of the dissection. The submaxillary is the second of the salivary glands, of an oval form and pale colour, surrounded by cellular membrane and several absorbent glands, covered by the skin, platysma, and fascia, bounded posteriorly by the digastric tendon, externally by the internal ptery- goid muscle and stylo-maxillary ligament ; anteriorly by the side of the maxilla, and internally by the anterior belly of the digastric ; it rests on the mylo-hyoid, stylo-hyoid, and hyo-glossus muscles ; a small process of the gland accompanies its excretory duct, turns round the posterior edge of the mylo-hyoid, and lies between the upper sur- face of that muscle and the membrane of the mouth ; this process fre- m-MUN i>issi:rn>K. :',."> quently joins tin- sublingual gland. The facial artery and vein pass through a deep groove in this gland. The duct of this gland is called li'Jiartiniinn duct, it arises by numerous fine coecal radicles from the lobules of the gland, leaves it at its outer end, winds above the mylo- hyoid muscle, and rims forwards and inwards towards the franium lingua 1 , by the side of which it open* into the mouth ; the orifice can lie distinctly seen in the mouth in a prominent papilla, which appears when the anterior part of the tongue is raised ; this duct is about two inches and a half long, is thin and transparent, its coats are weaker, but its calibre is larger than in Steno's duct, the gustatory nerve ac- companies it, at first superior, but afterwards inferior to it ; sometimes a second or accessory duct is met with. The submaxillary gland is subject to the same morbid changes as those which have been alluded to in speaking of the parotid gland. Its removal in case of scirrhus is also spoken of by authors, and this operation has been described as having been frequently performed ; most probably, however, many of these recorded accounts were rather cases of tumours which have pressed this gland aside, or, causing its absorption, have thus come to occupy its place. The Whartonian duct is not unfrequently obstructed near to, or closed at its termination in the mouth, the saliva, and often calcareous matter, then distend it into the form of a tumour of variable size, which is situated beneath the tongue, and causes more or less inconvenience to the latter ; this dis- ease is termed Ranula. Detach this gland from the mylo-hyoid, turn it outwards, leaving the duct and deep process to be further examined afterwards ; separate the anterior belly of the digastric from the chin and we see the following muscle : MYLO-HYOIDEUS, triangular, arises from the oblique line (the my- loid ridge,) on the inner surface of the side of the maxilla, which line descends obliquely from beneath the last molar tooth towards the chin ; the fibres descend obliquely inwards and backwards to the mesial line, and are inserted into the base of the os hyoides, and along with its fellow, into a middle tendinous line between that bone and the chin, which latter point they seldom reach. Use, to elevate the os hyoides and tongue, so as to press the latter against the palate. This muscle is covered by the submaxillary gland, and by the digastric ; it lies on the hyo-glossus, stylo-glossus, and genio-hyoid muscles, and conceals the AVhartonian duct, the lingual and gustatory nerves, and sublingual gland. This pair of muscles seem like a digastric muscle, the tendon being in the mesial line, opposite to the raphe in the pharynx ; they might almost be considered as continuations of the superior constric- tors of that organ, the gustatory nerve at each side intervening and marking the separation. Detach this muscle from the os hyoides and from its fellow ; in the middle line we shall then see the following pair : GEXIO-HYOIDEUS, short and round, arises by a small tendon on the inner side of the chin, above the digastric, descends obliquely back- i) 2 6(j DUBLIN DISSECTOR. wards, and is inserted broad and fleshy into the base of the os hyoides. Use, to draw the os hyoides upwards and forwards, to push the tongue against the incisor teeth, or protrude it from the mouth ; this pair of muscles lie superior to the digastric and mylo-hyoid, and inferior to the genio-hyo-glossus. Reflect the genio and mylo-hyoid muscles towards the lower jaw, and the sublingual space within the submax- illary will be exposed ; the mucous membrane of the mouth bounds this above, the side of the tongue and pharynx internally, the mylo- hyoid muscle forms its floor. In this space are lodged the sublin- gual gland adhering to the mucous membrane, the gustatory and lingual, or the sentient and motor nerves of the tongue, with their connecting plexus, on the surface of the hyo-glossus muscle, the chorda tympani thrown off from the gustatory to the submaxillary ganglion, the Whartonian duct rising obliquely forwards to the side of the frre- num lingua?, accompanied usually by a lobe of glandular structure, a soda, as in the case of Steno's duct, the lingual artery emerging from under the hyo-glossus, and dividing into the sublingual and ranine, the styloid and lingual muscles, and the glosso-pharyngeal nerve winding around the stylo-pharyngeus muscle. Observe how any change of position of the head, neck, or jaw, affects this space as to dimension, aspect, and form ; any such, therefore, during life, must ma- terially influence an examination or operation in this region ; if the jaw be depressed, or the neck flexed, it will become compressed, or almost obliterated within the side of the jaw ; but if the moiith be closed, and the head thrown back and slightly turned to the opposite side, it will present an extended plane surface, through which the sub- maxillary gland can be felt and even seen. In this gland and the surrounding cellular tissue inflammation occasionally occurs with much swelling and suppuration beneath the cervical fascia ; the abscess in some cases opens into the mouth ; haemorrhage is not uncommon, and it may be necessary to open the cavity through the skin. A free semi- circular or crucial incision will open it into a superficial cavity, but a small vertical wound will only give the appearance of a narrow pit, or deep axilla, without exposing its contents to view. The sublingual is the third and smallest of the salivary glands, oblong, placed beneath the anterior and lateral part of the tongue, covered superiorly by the mucous membrane, to which it adheres, and resting inferiorly on the mylo-hyoid, is in contact internally with the genio-hyo-glossus, and is connected externally to the deep process of the submaxillary gland, and partly resting in a depression in the lower maxilla. This gland opens by several small ducts, some of which join the Whartonian canal, others perforate the mucous mem- brane of the mouth, between the tongue and inferior canine and bicus- pis teeth, by small openings which may be observed on a sort of crest or fold of the mucous membrane in this situation. The three salivary glands, though generally separated from each other, yet are in some cases so joined together as to resemble one irregular glandular mass, the parotid being united to the submaxillary behind the angle of the D11U.1N DISSECTOR. jaw. ami the latter being connected to the subliiigual around the inylo- hyoid muscle. Fig. 5.* HYO-GLOSSUS is flat and thin, arises from the cornu and part of the body of the os hyoides, ascends a little outwards, inserted into the side of the tongue. Use, to render the dorsum of the tongue convex by depressing its side; it may also elevate the os hyoides and base of the tongue. This muscle is covered by the mylo-hyoid, by the duct and deep lobe of the submaxillary gland, also by the sublingual gland and lingual nerve, and a plexus between this and the gustatory nerve; it lies on the middle constrictor of the pharynx, the lingual artery, and the substance of the tongue. GEXIO-HYO-GLOSSUS is triangular or fan-shaped, arises by a small tendon from an eminence inside the chin, beneath the fraenum linguae ; thence the fibres radiate, the superior ascend, and turn forwards towards the tip of the tongue ; the middle also ascend, some inclining forwards, others backwards ; the inferior and posterior pass backwards and down- wards to the base of the os hyoides ; inserted into the mesial line of * The styloid muscles and muscles of the tongue. 1. The superior maxillary bone. 2. The malar bone. 3. A portion of the ramus of the inferior maxillary bone drawn upwards in order to shew the origin of the styloid muscles. 4. The styloid proee>s of the temporal bone. 5. The inferior maxillary bone divided at the symphysis. 6. The genio-hyo-glossus muscle. 7. The hyo-glossus. 8. The stylo-glossus. !). The stylo-maxillary ligament. 10. The stylo-hyoid ligament. 11. The stylo-hyoideus muscle. 1-'. The stylo-pharyngeus muscle. 13. The genio-hyoideus muscle. 14. The thyro-hyoideus muscle. 15. The tongue. 38 DUBLIN DISSKCTOK. the tongue from the apex to the base, and into the body or cornu of the os hyoides. Use, the posterior fibres can draw the os hyoides towards the chin, and thus protrude the tongue from the mouth, and bend its tip down towards the frsenum ; the middle por- tion can depress the middle of the tongue and make it concave from side to side ; it can also draw it forwards so as to enlarge the opening of the fauces. This muscle is therefore used in mastication and deglu- tition, also in the articulation of several letters. The several muscles last described cover this muscle externally, internally it is in contact with its fellow. LINGUALIS is a fasciculus of fibres taking a longitudinal course on the inferior surface of the tongue from the base to the apex, and inter- mixing with the muscles on either side, so that it appears as being derived from these rather than a distinct muscle ; the fibres are at- tached through their whole length, and are mixed with a soft, fatty substance, with but little cellular tissue ; anteriorly they are broader and more distinct ; they are situated between the genio-hyo-glossus internally, and the hyo and stylo-glossus externally. Use, to shorten the tongue and bend the tip downwards and to one side. External to the muscles now described, we see the three styloid muscles. STYLO -HYOIDEUS arises from the outer side of the styloid process near its base, descends obliquely forwards parallel to the posterior belly of the digastric, whose tendon generally perforates this muscle ; inserted into the cornu and body of the os hyoides and into the fascia, which connects the digastric tendon to this bone. Use, to cooperate with the posterior part of the digastric, in raising and drawing back the os hyoides and tongue. This muscle is nearly superficial, but at first is covered by the parotid ; the digastric lies to its external side and the external carotid artery to its internal ; this vessel is posterior to the lower part of the muscle, but anterior to its origin ; a ligament often accompanies the stylo-hyoid muscle, from the styloid process to the cornu of the os hyoides ; it is named the stylo -hyoid ligament, and is sometimes ossified. Raise the digastric and stylo-hyoid, and we see the remaining styloid muscles. STYLO-GLOSSUS arises tendinous and narrow from the inner side of the styloid process near its point, and from the stylo-maxillary liga- ment ; descends obliquely forwards and inwards, and is inserted into the side of the tongue ; its fibres overlap and unite with those of the hyo-glossus, and can be traced as far as the tip. Use, to draw the tongue backwards, and to one side, and to raise the tip behind the upper incisor teeth. It is covered by the sub-maxillary and lingual glands, by the gustatory nerve and mucous membrane. STYLO-PIIARYNGEUS, long and narrow, arises from the back part of the root of the styloid process, descends inwards and very h'ttle forwards, passes between the superior and middle constrictors of the pharynx, with which it mixes ; is inserted with these into the side of the phaiynx, also into the cornu of the os hyoides and thyroid car- tilage. Use, to elevate and dilate the pharynx, so as to receive the DUBLIN DISSECTOR. 39 food from the tongue. It is covered by the stylo-hyoid, middle con- strictor, and external carotid, and it lies on the superior constrictor, internal carotid, sympathetic, and par vagum ; the glosso-pharyngeal nerve winds round it. SECTION II. DISSECTION OF THE VESSELS AND NERVES OF THE NECK. THE arteries which are met with in dissecting the neck, are the ca- rotid and subclavian of each side, and their several branches ; the veins are the external and internal jugular and subclavian, with numerous branches ; the nerves are the gustatory branches of the fifth, the eighth, and the ninth pair, the sympathetic, and the anterior branches of the eight cervical and first dorsal spinal nerves. The right carotid artery arises from the arteria innominata, behind the right sterno-clavicular articulation ; the left carotid arises from the upper part of the arch of the aorta ; in other respects these arteries are nearly similar ; both as- cend by the side of the trachea and larynx, surrounded by a sheath of cellular membrane, on the forepart of which are seen the branches of the descendens noni nerve ; behind the sheath lies the sympathetic, and within it are the jugular vein, lying to the outside of the artery, and the par vagum nerve, between, and rather behind both these ves- sels ; opposite the os hyoides, each carotid divides into two branches, viz., the internal and external ; the internal carotid artery is the larger branch, lies deeper in the neck, and more external ; it ascends tortuously along the forepart of the transverse processes of the vertebrae to the base of the cranium, enters this cavity, through the foramen caroticum in the temporal bone, and is distributed to the brain. The external carotid artery ascends towards the parotid gland, being crossed by the digastric and stylo-hyoid muscles, and by the lingual and portio dura nerves ; in this course it gives off several branches, viz., the superior thyroid, lingual, labial or facial, auricular, occipital, pharyngeal, transverse facial, internal maxillary, and temporal. The subclavian arteries are situated at the inferior and lateral part of the neck ; the right arises from the arteria innominata, the left from the posterior part of the arch of the aorta ; each subclavian artery passes upwards and outwards to the anterior scalenus, behind which it passes ; it then turns downwards and outwards behind the clavicle, and over the first rib, into the axilla ; the difference in the origin causes an important difference in the situations and connexions of the right and left subclavian in the early part of their course ; the right, being shorter and nearly transverse, lies higher in the neck, and more super- ficial than the left, which arises deep in the thorax, out of which it ascends perpendicularly before it turns outwards to pass between the 40 DUBLIN DISSECTOR. scaleni ; after this point, these vessels are similar in every respect, and give off the following branches, viz., arteria vertebralis, mam- maria interna, axis thyroidea, cervicalis profunda, and inter-costah's superior. The external jugular vein has been already noticed ; the internal jugular vein of each side commences at the termination of the lateral sinus in the foramen lacerum posterius, descends along the outer side, first, of the internal, and afterwards of the common carotid artery, and at the inferior part of the neck joins the subclavian vein, which returns the blood from the upper extremity, and accompanies the subclavian artery, but separated from it by the anterior scalenus muscle; the junction of each jugular and subclavian, which is posterior to the ster- nal end of each clavicle, forms the right and left vena? innominatse ; these veins enter the chest, and uniting, commence the superior vena cava, as will be seen in the dissection of the thorax. (For the par- ticular description of the vessels of the neck, see Vascular System). The gustatory nerve is the principal branch of the inferior maxillary or third division of the fifth pair ; it is seen, on dividing the mylo- hyoid, taking an arched course below the sublingual gland, parallel to the lingualis, and stylo-glossus muscles, from within the angle of the jaw towards the tip and side of the tongue ; it accompanies the Whar- tonian duct, at first above, afterwards beneath it, and then rises above the sublingual gland, between it and the tongue ; it gives branches to the submaxillary and sublingual glands, and terminates in fine fila- ments, which are lost in the papilla) beneath the mucous membrane co- vering the sides and tip of the tongue. The chorda tympani joins it near the condyle, and parts from it opposite the angle of the lower maxilla ; this delicate nerve then swells into a small ganglion, whose branches pass into the submaxillary gland. The eighth pair of nerves leave the cranium by the foramen lacerum posterius, anterior to the jugular vein ; it immediately separates into its three portions, the internal or glosso-pharyngeal, the external or spinal accessoiy, and the middle or par vagum. The glosso-pharyngeal is connected to the stylo-pharyngeus muscle, its name denotes its destination ; the arch which it forms, as it runs to the base of the tongue, is inferior to and deeper in the neck than the gustatory nerve. The spinal accessory nerve separates from the par vagum, and in general winds round be- hind the internal jugular vein, perforates the sterno-mastoid muscle, as was before mentioned, and distributes its branches to it and to the trapezius ; several of these also communicate with the cervical plexus, and descend towards the acromion. The par vagum or pneumogastric descends along the neck, between, and rather behind the carotid artery and jugular vein, and enclosed in their sheath ; it then passes through the thorax, and terminates on the stomach. The cervical portion only of this nerve is to be observed at present ; from it arise .several branches, viz., communicating branches to join the sympathetic and lingual ; pharyngeal branches to the side of the pharynx ; superior laryngeal nerve, which takes an arched course behind the great vessels to the PIT, I. IX DISSECTOR. -11 thyroid cartilage, and is distributed to the upper part of the larynx; and small cardiac branches, which join, .similarly named branches of the sympathetic nerve. At the inferior part of the neck, on each side of the trachea, a large nerve, the inferior luryugealm recurrent nerve, is seen ; this is also a branch of the par vagum. On the right side, this nerve urines at the lower part of the neck, turns round the subclavian artery, and passing In-hind it and the carotid, pursues its course up- wards and inwards, behind the thyroid body, to the lower and back part of the larynx ; on the left side the recurrent nerve arises in the thorax, opposite to the lower part of the arch of aorta, under which it passes, and then attaching itself to the forepart of the oesophagus, as- cends to the larynx, to the muscles of which it is distributed like that of the opposite side. At the inferior part of the neck, the eighth pair of nerves enter the thorax ; that of the right side passes anterior to the subclavian artery, crossing it at a right angle ; that of the left side descends anterior but parallel to the left subclavian artery. The ninth pair, or lingual nerve, leaves the cranium by the anterior condyloid hole hi the occipital bone, descends forwards and inwards, nearly pa- rallel to the digastric muscle, and is distributed to the muscles of the tongue ; the arch which the course of this nerve describes is parallel, but inferior to that of the gustatory. From the convexity of this arch a long branch arises, the descendens noni ; this descends along the forepart of the sheath of the carotid artery, communicates with the second and third cervical nerves about the middle of the neck, and is distributed to the omo and sterno-hyoid and thyroid muscles : in some cases this nerve descends within the sheath and behind the vein. The sympathetic nerve may be found descending along the vertebrae poste- rior to the carotid artery : this nerve commences at the base of the cra- nium, in a long, oval, red swelling, the superior cervical ganglion, which extends as IOAV as the third cervical vertebra ; from tin's the nerve, becoming very small, descends almost vertically, and in general opposite the fifth cervical vertebra it forms a second swelling, called the middle cervical ganglion ; from this the small nervous chord con- tinues its course down the neck, behind the sheath of the vessels, and op- posite the seventh cervical vertebra, and the neck of the first rib, it ex- pands into a large irregular swelling, the inferior cervical ganglion, from the lower part of which the nerve descends into the thorax. On the side of the neck are seen numerous branches of the cervical spinal nerves : there are eight pair of cervical nerves ; the first, or suboccipital, is very small ; the eighth is very large ; the first leaves the spinal canal between the occipital bone and the atlas ; and the eighth between the last cervical and 1ir>t dorsal vertebra: these cervical nerves all divide into a posterior and anterior branch, the former are distributed to the muscles and integuments on the back of the neck ; the anterior branches of the first, second, third, and fourth, communicate with each other, and give origin to several branches, which again unite with each other, and constitute the cervical plexus ; this plexus is between the mastoid and trapezius muscles ; it sends off several branches, which 42 DUBLIN DISSECTOR. are entangled with much cellular membrane, and several absorbent glands : the anterior branches of the four inferior cervical nerves, with that of the first dorsal, unite and form the brachial plexus ; this is si- tuated at the lateral and inferior part of the neck, and accompanies the subclavian artery beneath the clavicle into the axilla, in which region the plexus divides into several branches to supply the upper extremity and the muscles on the parietes of the thorax. In the inferior and la- teral parts of the neck, on each side, the phrenic nerve is also seen ; this arises by several fine filaments, from the third, fourth, and fifth cervical nerves ; the phrenic nerve descends obliquely inwards along the anterior scalenus muscle, enters the thorax between the subclavian vein and artery, and is distributed to the diaphragm. (For the par- ticular description of the branches of the sympathetic, as well as of the cerebral nerves, met with in the dissection of the neck, see the Ana- tomy of the Nervous System). Previous to examining the deep mus- cles of the neck, the student should study the anatomy of the mouth, pharynx, and larynx. SECTION III. DISSECTION OF THE MOUTH, PHAKYNX, AND LARYNX. THE cavity of the mouth may be exposed by dividing the commis- sure of the lips, and the cheek of one side, and removing a small por- tion of one side of the lower jaw; draw for- Fig. 6.* wards and fix the tongue with a tenaculum, and cleanse the parts veiy well. The mouth is bounded anteriorly by the lips, superiorly by the hard and soft palate, laterally by the cheeks, inferiorly by the tongue, and mucous membrane reflected from it to the gums ; pos- teriorly it communicates with the pharynx; this opening is named the isthmus faucium, is bounded above by the velum and uvula, below by the tongue, on each side by the arches of the palate. The anterior part of the palate, or hard palate, is formed of the pa- late plates of the maxillary and palate bones, covered by mucous membrane and glands ; the posterior part of the palate, or soft palate, or velum pendulum, consists of a dense aponeurosis, and of several mus- cles and glands, enclosed in mucous membrane. The cheeks are formed of mucous membrane, covered by the bucci- nator and a quantity of fat ; several small mucous glands lie between * The cavity of the mouth. 1. The upper lip. 2. The lower lip. 3. The in- ternal surface of the cheeks. 4. The tongue. 5. The velum pendulum palati, and uvula. 6. The oesophagus. IH 15I.IN IH-iSMTOn. 43 tlu- membrane and tin's muscle, and towards the upper and back part on each side we perceive the small opening- of Steno's duct. The lips are composed of integuments with more or less of fat, mus- cli's. vess.-ls, nerves, glands, and mucous membrane. The skin is delicate, and vascular, particularly at the red borders, where it is continuous with the mucous membrane of the mouth. The cuticle is continued over the latter to line the whole cavity as a very fine epi- thelium. The muscles are the orbicularis oris, with which the fibres of many others (already described) intermingle. The arteries of the lips are the coronary vessels, assisted by their inosculations with branches of the internal maxillary artery. The sentient nerves are derived from the infra-orbital and dental branches of the fifth, and the motor from the seventh pair. The labial glands are very numerous, they are rounded and pale, and are situated in the submucous loose cellular tissue, at some distance from the red border. The mucous membrane is continued from each lip to the alveolar processes of the maxilla?, and forms in the centre of each a small fold or fraenum ; this is larger in the upper than in the lower lip. The mouth is lined throughout by mucous membrane, which is con- tinuous with the cutis on the lips, and extends posteriorly through the pharynx, whence it ascends to line the nares, the Eustachian tube, and tympanum on each side, and descends to line the oesophagus and larynx : it is also continued into the ducts of the sublingual, submax- illaiy, and parotid glands ; as it is reflected from one surface to another, it forms folds or fra?na, as between the lips and alveoli, and beneath the tongue ; at the sides of the fauces, also, it forms two semilunar folds on each side, called the pillars or arches of the palate ; these folds enclose muscular fibres, which we shall examine afterwards. On looking into the mouth, either in the living or dead subject, the folio whig objects strike the attention ; inferiorly the tongue and in- ferior teeth ; laterally the cheek ; posteriorly the back part of the pharynx ; superiorly, the superior teeth, the hard and soft palate, from the centre of the latter, the nvula, and from the sides, the pillars or arches descending to the tongue and pharynx ; in the recess between these pillars on each side, the tonsil or amygdala is also seen ; lastly, if the tongue be drawn forward, the epiglottis comes into view. The tongue, though somewhat triangular, is of a very variable shape ; its base, thick and broad, is connected to the epiglottis, and to the palate by folds of mucous membrane, the former are the fraena of the epi- glottis, the latter are the arches of the palate, and to the os hyoides and inferior maxilla by muscles, to the latter also by a mucous fold, the fnviium lingua? ; the apex is thin and imattached ; that portion be- tween it and the base is named the body of the tongue ; all the up- per surface, the sides, and about one-third of its inferior surface, are covered by mucous membrane, which is very rough superiorly, from the number of papilla? that project through it ; anteriorly, these pa- pilla? are small, conical, and connected with the terminations of the nerves of taste ; posteriorly, they are large, rotuid, fungiform, lenticular, DUBLIN DISSECTOR. and very irregular ; these are small glands which open on the mu- cous surface ; near the epiglottis these glandular papillae are often ob- served to have a peculiar arrangement, like the letter v, the concavity turned forwards ; these are of a conical form, the apex attached in a little membraneous cup or calyx ; behind p iljf 7 * the apex of this angle, a deep depression (foramen coecum) is observable ; this con- tains some mucous follicles ; a superficial groove or raphe runs along the dorsum of the tongue, one more distinct exists along the inferior surface, and a cellulo-ligamen- tous line divides it mesially into two sym- metrical portions, this line is more distinct near the base ; in some animals it is very dense and even bony ; in paralysis one side only of this organ is frequently found af- fected.f The substance of the tongue is composed of adeps blended with numerous muscular fibres derived from the stylo, hyo, genio-hyo-glossi, and lingualis muscles, and of many other fleshy fibres which do not properly belong to any of these ; two large ar- teries (lingual), and six considerable nerves (the gustatory, the lingual, and the glos- so-pharyngeal, on each side), supply this organ. The tongue is not only the organ of taste, but by its great mobility it assists in speech, in suction, and in deglutition. The fifth pair of nerves endow the tongue with sensation and with the sense of taste, the ninth with mo- bility, and the eighth supply its base with sensation, and connect the motions of this organ with those of the pharynx and stomach. (See Nervous System). The tongue is subject to many morbid changes, viz., inflammation, acute or chronic, causing a great and dangerous, and sometimes fatal enlargement ; tumours of different kinds may occur in it, also ulcera- tion, cancerous, syphilitic, apthous, &c. ; portions of this organ can be removed with safety, either by ligature or excision. * The muscles of the inferior region of the tongue. (Gerdy). 1. The body of the os hyoides reversed by the position of the tongue upon a horizontal plane. 2. 2. Its greater cornua turned forwards instead of backwards. 3. Its appendix or lesser cornu. 4. The hyoidean appneurosis of the genio-hyo-glossns. 5. The right hyo-glossus muscle. 6. The left hyo-glossus detached from the os hyoides and turned aside. 7. 7. Longitudinal portions of the stylo-glossus muscles. 8. 8. Posterior and interior fibres of the genio-hyo-glossi. 9. 9. Their anterior fibres. 10. Their middle fibres. 11. 11. Section of the inferior angle of each of 12. 12. The lingualis profundus. hemiplegia, when the muscles of one side of the face are paralysed, it ;n remarked that, if the tongue be protruded, the apex will be directed the gen t In! has been remar towards the affected side ; this phenomenon, which is only an apparent excep- tion, depends on the action of the genio-hyo-glossus muscle of the healthy side, which will pull the base of the tongue, on that side, towards the chin, and must therefore turn the point to the opposite side ; but if when protruded the point be moved towards the sound side, it cannot again be pointed to the paralysed side. 1 T1U. IN DISSECTOR. SECTION IV. DISSECTION OF THE PHARYNX. To obtain a view of the muscles of the pharynx and palate, the stu- dent may now make the following dissection: divide the trachea and (esophagus in the lower part of the neck; detach them from the ver- tebra', to which they are loosely connected ; draw forward these organs, together with the vessels and nerves on either side ; place the saw flat on the bodies of the vertebne: insinuate its edge betAveen the styloid and mastoid processes on each side, and make a A~ertical section of the head ; Ave have thus the face and anterior part of the cranium sepa- rated from the vertebral column; or, should it be desirable to pre- serve the cranium, we may separate the occipital bone from the atlas, and then remove from the subject the Fig. 8.* whole head, together with the organs we wish to examine ; distend the pharynx Avith cotton, curled hair, or tow. and remoA'e some of the loose cellular tissue connected to it. It is quite possible, however, for the stu- dent to dissect the pharynx from the f< >re] >art of the neck ; indeed it is de- sirable that he should examine this organ in both these aspects. The pharynx is a large, muscular, and membranous bag. extending from the base of the cranium to the fourth or fifth cervical A'ertebra, Avhere it contracts and ends in the oesophagus behind the cricoid cartilage ; it is placed behind, and communicates with the nose, mouth, and larynx; is somewhat of an OA*al form, the largest part being opposite the os hyoides, and the smaller extremity joining the esophagus. The pharynx is attached superiorly and posteriorly to the cuneiform process, by an aponeurosis, which is very strong in * A posterior view of the muscles of the pharynx. 1. A vertical section carried transversely through the base of the skull. 2. The posterior border of theramus. 3. The angle of the inferior max ilia. 4. The internal pterygoid muscle. 5. The styloiil process of the temporal bone, giving attachment to, 6. the stylo-pharyn- sreua muscle. 7. The inferior extremity of the stylo-pharyngeus muscle, attached to the superior comu and posterior border of the thyroid cartilage. 8. The infe- rior constrictor of the pharynx. 9. The middle constrictor of the pharynx, 'partly covered on the left side by the inferior constrictor. 10. The superior'constrictor of the pharynx. 11. The external surface of mucous membrane of pharynx, un- covered by muscular fibres. 46 DUBLIN DISSECTOR. the middle line, laterally by a thinner aponeurosis to the petrous bone, and anteriorly, by fleshy fibres, to the internal pterygoid plate and hamular process, to the posterior part of the mylo-hyoid ridge of the lower maxilla, and to the sides of the tongue. The pharynx is con- nected posteriorly to the vertebrae, and to the deep muscles of the neck, by loose reticular membrane ; anteriorly, by mucous membrane and muscular fibres, to the cornua of the os hyoides and thyroid cartilage, and to the sides of the cricoid, behind which it abruptly contracts and ends in the oesophagus ; on either side of it are the styloid process with its muscles, and the sheath of the carotid artery with its ac- companying nerves. The pharynx is composed of muscular fibres, placed in successive strata, of mucous membrane, and of an intervening aponeurosis, which superiorly forms, as it were, its framework for the attachment and sup- port of the investing muscles, and the lining membrane. Thepharyn- geal aponeurosis is stronger mesially than laterally, is attached above and behind to the cuneiform process, and to the Eustachian tubes, descends mesially as a raphe or linea alba, and for about an inch and a half retains considerable strength, receiving the insertions of the con- strictor muscles ; laterally it is attached to each petrous bone internal to the carotid foramen and to the superior cervical ganglion by a strong band, which is continuous with the middle portion, and descend- ing expands into different processes, of which some continue between the muscular and mucous walls of the pharynx, as low down as the os hyoides ; others pass external to the superior constrictor, and are in- serted, some into the pterygoid fossa, between the tensor palati and in- ternal pterygoid muscles; others, encircling the tonsil, reach the posterior part of the inferior alveolar arch and the buccinator muscle. The mucous membrane is continuous with that lining the mouth, nares, and Eustachian tubes, and is continued inferiorly as a lining to the larynx and trachea in front, and the oesophagus behind ; it is soft, vascular, highly organized, very sensible, studded with numerous mu- cous glands, and covered with a fine epithelium. The muscular fibres which cover the back and sides of the pharynx, are named constrictor muscles ; they are symmetrical, and are three in number on each side, they are named the superior, middle, and infe- rior ; they overlap each other, the inferior being most superficial, the middle next, and the superior the deepest ; the constrictor muscles of opposite sides have one common insertion into the middle tendinous line, or raphe on the back part of the pharynx, which line is very strong and distinct superiorly, being inserted into the cuneiform pro- cess, but inferioTly is weak and often indistinct. CONSTRICTOR PHARYNGIS INFERIOR is of an irregular form, the anterior and inferior borders being shorter than the superior and pos- terior; arises by two heads, one from the side of the cricoid cartilage (crico-pharyngeus of some), the other from the inferior cornu and pos- terior part of the ala of the thyroid carilage, external to the crico- thyroid and thyro-hyoid (thyro-pharyngeus of some) ; the superior nrr.i.ix DISSECTOR. fibres ascend obliquely, and overlap Fig. 9.* the middle constrictor; the inferior fibres, a few of which often arise from the trachea, rnn circularly and over- lap the oesophagus ; inserted, along with that of the opposite side, into the middle line or raphe on the back of the pharynx; its origin is covered by the sterno-thyroid muscle, and the thyroid gland ; it lies on the mu- cous membrane, except its superior fibres, which are separated from it by the middle constrictor. The in- ferior laryngeal or recurrent nerves pass beneath its lower edge, and the superior laryngeal above its upper ; the inferior head or origin is be- tween the crico-thyroid and crico- arytenoideus posticus muscles ; and the superior between and behind the attachments of the sterno-thyroid and thyro-hyoid. CONSTRICTOR PHARYNGIS MEDirs, or HYO-PHARYNGEUS (im- properly called constrictor), is of a triangular form, arises from the cornu and appendix of the os hyoides, also from the stylo-hyoid and posterior thyro-hyoid ligaments ; its fibres expand on the back of the pharynx, the superior ascend to the occipital bone, the middle run transversely, and the inferior descend beneath the lower constrictor, inserted into the mesial tendinous line or raphe, and into the cuneiform process. The lingual artery and hyo-glossus muscle are connected to its origin, which is separated from the inferior constrictor by the su- perior laryngeal nerve and cornu of the thyroid cartilage, and from the superior constrictor by the stylo-pharyngeus muscle and glosso-pha- ryngeal nerve ; on dividing the edge of this muscle, the STYLO- PHARYNGEUS appears ; it arises from the root of the styloid process, descends to the side of the pharynx, where it expands between the superior and middle constrictors, and is inserted beneath the latter, partly into the submucous tissue, and partly into the cornu of the thyroid cartilage. Use, to elevate, dilate, and shorten the pharynx, and draw it slightly backwards, in order to receive the food from the tongue ; it will also raise the larynx. Divide the stylo-pharyugeus, and the superior constrictor will be exposed. * A lateral view of the muscles of the pharynx. 1. The zygomatic arch. 2. The external pterygoid plate. 3. The hamular process of the internal pterygoid plate. 4. The intermaxillary, or pterygo-maxillary ligament. 5. A portion of the in- ferior maxillary bone. 6. The os hyoides. 7. The thyro-hyoid membrane or ligament. 8. the thyroid cartilage. " 9. The cricoid cartilage. 10. The trachea. 11. The oesophagus. 12. The inferior constrictor of the pharynx. 13. The mid- dle constrictor. 14. The superior constrictor. 15. The buccinator muscle. 16. The mylo-hyoid muscle. DUBLIN DISSECTOR. CONSTRICTOR PHARYNGIS SUPERIOR, surrounds the superior part of the pharynx; arises by a dense aponeurosis from the petrous bone (which is, in fact, the lateral or bucco-pharyngeal portion of the pharyngeal aponeurosis) ; this soon becomes connected with the next origin, which is fleshy, from the lower part of the internal pterygoid plate and hamular process, also from the pterygo or intermaxillary ligament (see page 11), which connects it to the buccinator imiscle, from the posterior third of the mylo-lvyoid ridge, and from the side of the base of the tongue, between the stylo and hyo-glossus muscles ; all the fibres take a semicircular course backwards and inwards, and are inserted into the cuneiform process and into the middle tendinous line on the back of the pharynx. The superior constrictor is covered by the styloid muscles and by the great vessels and nerves, and inferiorly by the middle constrictor, from which the stylo-pharyngeus and glosso- pharyngeal nerve separate it ; between the lateral attachments to the petrous bones and the mesial one to the occipital, the mucous membrane and fascia are uncovered by muscular fibres in a small semicircular space, named sinus of Morgagni ; this is beneath the cuneiform pro- cess, on each side of the middle line, and internal to the Eustachian tube ; between the temporal and ptery- Fig. 10.* goid attachments, the levator palati muscle is seen, and between the ptery- goid and maxillary origins the internal pterygoid muscle and the gustatory nerve are situated. Use, the constric- tors, particularly the upper and lower, diminish the capacity of the phaiynx ; the inferior can also elevate the os hyoides and tongue, and shorten the pharynx ; by the successive contrac- tions of each, the food is forced into the oesophagus ; the complex mus- cular structure of the pharynx may also assist in the modulation of the voice and in the production of certain sounds. Open the pharynx by a perpendi- cular incision through the middle tendinous line ; on looking into the cavity it will be found divided by the velum and uvula into two por- * The pharynx, laid open from behind. 1. A vertical section carried transversely through the base of the skull. 2. 2. The walls of the pharynx drawn to each side ; on the right side the mucous membrane has been removed, in order to shew the internal surface of 3. The superior constrictor, and 4. The middle constrictor. 5. The palato-pharyngeus muscle. 6. 6. The posterior nares, separated by the vomer. 7. The levator palati. 8. The vertical portion of the circumflexus palati. 9. The extremity of the Eustachian tube of the right side. 10. The isthmus faucium. 11. The base of the tongue. 12. The epiglottis, and beneath it the superior opening of the larynx. The commencement of the oesophagus. 14. A portion of the internal pterygoid muscle. 4!) tions, ;i superior and inferior: seven openings also may be remarked leading from it in different directions, viz., in the upper or nasal portion there are the two posterior nares, and on the side of each of these is the opening of the Kustarhian tube; below the velum is the isthmus faucium or posterior opening of the mouth; below and behind the tongue is the opening of the glottis ; and lastly, the termination of the pharynx in the oesophagus. The openings of the nares are of an oval shape, their long diameter being vertical ; the body of the sphenoid bone bounds them superiorly, the palate bones inferiorly, the internal pterygoid plates externally, and the vomer, with a fibrous prolongation from its periosteum, sepa- rates them from each other ; all these bones are covered by the mucous membrane ; through these, which are permanently open, the air gene- rally passes during respiration. The Eustachian tubes open on each side of the posterior nares, be- hind the inferior spongy bone ; they are circular, and look downwards, forwards, and inwards towards the septum narium, are formed, in two- thirds of their circumference, of thick cartilage, covered by mucous membrane; through these, air is admitted from the nose and pharynx into the tympanum, to support the membrana tympani on its inner side. The Eustachian tube must be again examined in the dissection of the organ of hearing.* Beneath the velum is the isthmus faucium, transversely oval, but raj table of great change in figure and size, bounded above by the ve- lum and uvula, below by the tongue, and on either side by the pil- lars or arches of the palate, and by the amygdala?. The opening of the glottis, or superior opening of the larynx, is at the lower and anterior part of the pharynx, behind the epiglottis, and rather beneath the tongue; it is of a triangular form, the base ante- riorly formed by the epiglottis ; the sides are composed of folds of mucous membrane, termed aryteno-epiglottidean, and the apex, which is posteriorly and a little notched, is formed by the appendices of the arytenoid cartilages ; the sides are somewhat thickened and strength- ened by two small nbro-cartilages enclosed between the mucous folds (cuneiform cartilages or bodies). The glottis, which will again be con- sidered in speaking of the larynx, is always open, except in the act of deglutition. The oesophageal opening is below and behind the glottis ; it is always closed, except in deglutition. The student should next examine the velum pendulum palati, or palatum molle. * The student may practise the introduction of a probe into this tube ; slightly curve a blunt probe, pass it along the floor of the nose to the posterior nares, then direct its extremity upwards, outwards, and backwards, that is, towards the ear, and it will enter this tube. 50 DUIJLIN DISSEC'TOK. SECTION V. DISSECTION OF THE PAIATE AND ITS MUSCLES. THE velum pendulum palati, or palatum molle, is a soft, moveable partition, or valve, extending in a gentle curve the surface of the arched roof of the mouth, and the inclined plane of the nares, and se- parating the mouth and fauces from the nasal or superior region of the pharynx ; quadrilateral, its anterior and superior border, which is thick and strong, is firmly attached to the posterior part of the hard palate ; its posterior inferior margin is thin and concave, bounding the isthmus faucium ; from its centre a conical appendix (uvula) descends, and thus divides this margin into two slightly lunatecl portions, named by some the half arches of the palate. Its lateral limits are marked by a prominent ridge leading from the posterior part of the superior alveolar arch to that of the inferior one ; this ridge nearly corresponds to the anterior border of the internaJLpterygoid muscle, and contains a number of small mucous glands ; these are often collected into a dis- tinct, round cluster behind the last inferior molar tooth. The velum, when at rest, is placed obliquely ; near the hard palate it is horizontal, but towards its free margin it is curved downwards, so that the infe- rior or oral surface is concave, the superior convex ; on the former a dense, pale h'ne continued from the raphe on the hard palate marks it mesially and divides it into two symmetrical portions ; this surface looks downwards and forwards towards the tongue ; the opposite sur- face, also marked by a mesial raphe, but more prominent on either side, looks upwards and backwards ; during life these aspects are con- stantly being changed by the action of the muscles, which can depress, elevate, and make tense the velum. The uvula is a conical prolonga- tion of the mucous membrane of the velum, a sort of cul de sac, con- taining some muscular fibres superiorly, glands and cellular tissue inferiorly ; it hangs perpendicularly over the depression in the tongue, called foramen coecum, is not in contact, but so very close that nothing of any size can pass between them without affecting the sensibility of the uvula, whereby all the surrounding muscles are excited to action ; the point of the uvula is anterior to the epiglottis. This organ is very variable as to shape and size, it is sometimes a little bifid, sometimes nearly absent, and is wanting in almost all other mammalia, except the quadrumana. From either side of the uvula the mucous membrane of the velum is continued downwards in two folds, which contain muscular fibres, and are named the arches or pillars of the palate. The anterior arch or fold, passing from the base of the uvula, is curved downwards and outwards, and ends on the superior and lateral part of the tongue ; this fold is very concave inwards, and contains the palato-glossus or con- strictor isthmii faucium muscle. The posterior arch or fold arises near the point of the uvula, and is continued in a curved form from the free edge of the velum downwards, outwards, and backwards, and is lost in the side of the pharynx ; it contains the palato-pharyngeus muscle, ]>n;i.iN nissK.rTOK. . r I and is on a plane internal as well as posterior to the former; both these folds are somewhat triangular, the apex above, the base below, and as they diverge interiorly they leave a considerable spaee between them, in which the amygdala or tonsil of each side is lodged. This ton- silitic recess or ventricle is narrow and pointed above, broad and deep below, bounded before and behind by the arches of the palate, below by the base of the tongue and the mucous membrane passing from the pharynx to the epiglottis ; it corresponds externally and inferiorly to the angle of the jaw and to the integuments over the posterior part of the sublingual region. The velum is a highly organized structure, it is composed of a duplicature of mucous membrane, enclosing glands, celhdar tissue, nerves, and vessels, a strong aponeurosis forming the basis of general support, and several muscles designed to move it in different directions, namely, to elevate, depress, and make it tense. It is of great use in deglutition and in the modulation of the voice ; when depressed it conies into close contact with the tongue and closes the mouth posteriorly ; when elevated during the contraction of the pharynx it may touch the latter so as to separate or shut off the nasal division, and thus during deglutition or in vomiting prevents the food ascending into it and regurgitating through the nares and Eustachian tubes, its aponeurosis and tensor muscles regulate and restrict these motions and impart the necessary strength and resistance. The mucous membrane is continued from that of the hard palate, round the thin edge, to the upper surface, and is continuous with that covering the floor and septum of the nose ; the lamina? are in much closer apposition in the lunated borders of the free margin than in other situations ; a digital prolongation from the centre is produced downwards to constitute the uvula ; the lower surface is soft and vas- cular, resembling that in the adjacent regions, the upper, like that on the floor of the nose, is paler and thinner ; the mucous glands are but few above, but on the oral surface they form a thick, submucous layer, which is prolonged for a variable extent into the uvula. The palatine aponeurosis is very strong and laminated ; an inferior, weaker layer is continued from the hard palate, the submucous glands are intimately connected to it ; above this is a much stronger aponeurosis, formed partly of the expanded tendons of the tensor muscles, and partly of the fibrous tissue from the septum narium and adjacent bones. The muscles of the velum or soft palate are five pair, the levator and tensor palati, the motor uvula?., palato-glossus, and palato-pharyngeus. LEVATOR-PAI.ATI, thick and round, arises narrow from the petrous bone, in front of the foramen caroticum and behind the Eustachian tube, descends obliquely inwards, and is inserted broad into the velum near its centre : its name denotes its iise. It is situated on the side of the posterior nares, covered internally and posteriorly by mucous membrane, and externally by the tensor palati and superior con- strictor ; its insertion intermixes with its fellow, with the other muscles of the palate, and with the palato-pharyngeus. TENSOR PAI.ATI vel circumflexus palati, thin and slender, arises E 2 n DUBLIN DISSECTOR. fleshy from a depression at the root of the internal pterygoid plate, from the spinous process of the sphenoid, and from the forepart of theEus- tac.liian tube, descends between the internal pterygoid plate and muscle, ends in a flat tendon, which turns round the hamular process inwards to the velum, it then expands, and is inserted, with that from the opposite side, into the horizontal plate of the palate bones, and into the palatine aponeurosis. Use, to make tense the velum in a hori- zontal direction between the hamular processes ; it may possibly dilate the Existachian tube. MOTOR UVULAE, arises from the posterior extremity, or spine of the palate bones, or rather from the palatine aponeurosis, or fibrous conti- nuation of the septum narium ; descends close to its fellow along the median line of the nasal surface of the velum, and is inserted into the cellular tissue of the uvula. Use, to raise and shorten the uvula : this pair of muscles are so close that they appear but as one, hence they have sometimes received the name of azygos uvula. PALATO-GLOSSUS vel constrictor isthmi faucium, or the anterior arch or pillar of the palate, semilunar, narrow in the centre, broad at its extremities, arises from the inferior surface of the velum, descends a little forwards and outAvards, enclosed in a fold of mucous membrane anterior to the tonsil ; inserted into the side of the tongue, intermingling with the stylo-glossus. Use, to elevate the tongue or to depress the velum ; this pair of muscles may also close the fauces. PALATO-PHARYNGEUS, or posterior arch of the palate, arises broad from the inferior surface of the soft palate in common with its fellow ; arches downwards and backwards behind the tonsil, and is inserted into the side and back of the pharynx, and into the cornu of the thy- roid cartilage, its fibres mixing with those of the stylo-pharyngeus ; both this and the palato-glossus muscle are narrower in the centre than at their extremities. Use, to elevate the pharynx, like the stylo- pharyngei, in the commencement of deglutition, also to depress the velum, but chiefly to approximate the sides of the fauces and bring them, the tongue, and velum into contact. The tonsil, or amygdala, though apparently a compact body, is formed of a congeries of mucous glands, of an irregular figure, some- what oval, the larger extremity above, placed in a triangular recess between the pillars of the palate, above the side of the base of the tongue, and opposite the angle of the jaw ; covered internally by the mucous membrane, and externally by a fascia and by the superior constrictor of the phaiynx ; small holes are remarked on its surface ; these lead into interlobular cells from which the mucus can be ex- pressed. The amygdalae are very vascular and secrete a viscid fluid, which being pressed out in the moment of deglutition by the contrac- tion of the surrounding muscles, serves to lubricate the alimentary bolus in its passage. The internal carotid artery is posterior and somewhat external to it, and, when tortuous, very near to it ; the external carotid is also to its outer side, and the facial artery, just before it enters the i>i r-UN DISSI-X 101;. 53 Mihmaxillary gland, is anterior to it ; from these three vessels this gland, when of its healthv size, is separated by the superior constrictor, ami by a considerable interval which is filled by cellular tissue, but when enlarged, as in the case of abscess, it comes into such close con- tact with these, particularly with the intemal carotid, that there is some danger of wounding the latter in opening the abscess with the lancet. The group of muscles now described, though in a great degree vo- luntarv, yet rather belong to the mixed class ; the will can excite and control them only to a certain extent, it can even continue their actions for a time, but if there be no substance to be swallowed, their contrac- tions cannot be often repeated and volition is impotent ; they act, too, convulsively, and oftentimes without any cognizance ; deglutition occurs in sleep : the volition power is most enjoyed anteriorly, as in the tongue, lips, and cheeks; the mixed property prevails in the middle region ; the lower we descend the more involuntary is the mus- cular fibre, and so it is at the opposite or lower end of the alimentary canal, the mixed property and the volition power of the investing and surrounding muscles are gradually developed towards the orifice, while all the intervening muscular coat of the digestive tube is purely invo- luntary ; perhaps the muscular powers of the stomach, in some animals at least, may prove an exception to this general assertion. The sensi- bility to contact of the mucous membrane in the palatine region is very considerable, and exerts a rapid influence over the surrounding muscles through the reflex motor power of the nervous system, whereby the act of deglutition is effected ; this act, though momentary, and, as it were, convulsive, may be divided into three stages ; in the FIRST, which is in part only a continuation of mastication, the alimen- tary matter is pressed by the convex surface of the tongue, which is accu- rately and beautifully moulded to the vault of the palate, backwards into the space bounded by the anterior arches or pillars of the velum, that is, into the isthmus faucium ; during this stage the velum is depressed, and lies nearly in contact with the base of the tongue, the pharynx is in a state of rest ; this stage is accomplished chiefly by the muscles of the tongue and cheeks ; in the first instance the mouth is closed ante- riorly and the last agent is the constrictor isthmus faucium ; it is a voluntary act. In the SECOND stage, the alimentary matter is carried through the fauces and pharynx into the oesophagus ; the velum at first is made tense and slightly raised ; the tongue is retracted, the larynx drawn upwards beneath it so that the epiglottis is pressed or shut down over the glottis, and the alimentary mass glides over its centre and sides ; at this very instant the pharynx is advanced, its sides approximate, the velum descends a little, though still preserving the partition below the nares, and is held steady ; all the muscles now contract towards the base of the tongue, and thus a narrow inclined passage or chink conducts the food down to the oesophagus ; finally, the still contracting pharynx recedes ; and, last of all, the larynx descends coincident with the entrance of the morsel into the opening of the oesophagus. Tliis stage is effected not only without the influence of 54 DUBLIN DISSECTOR. the will, but even at times in opposition to it, although it may and does occasionally exert some power of control so as to retard, hurry, or even interrupt it. In the THIRD stage, the food descends along the oesophagus into the stomach by rapid, undulatory contractions, each portion of the tube first dilating to receive, and then contracting to propel, some- what analogous to the peristaltic action of the alimentary canal, and like that, too, wholly involuntary, and scarcely even giving rise to any sensation, unless the mass swallowed should be of inordinate magni- tude, or of a temperature extremely high or even very low, or unless the act be too rapidly repeated. Not only is the velum essential in deglutition, but it is also most usefully concerned in certain conditions of respiration, thus in suction it is indispensable ; in forced inspiration through the mouth, it is raised and made tense, and thus the whole of the air imbibed must descend into the chest, as none can enter the Eustachian tubes, or escape by the nares. In the modulation of the voice, the expression of sounds, words, and letters, it also acts an important part ; by being raised or depressed, made tense or loose to the requisite degrees, it produces the desired effect, and hence not only the difficulty of deglutition, but also the peculiar altered tone and indistinctness of voice and utterance when this organ is cleft or otherwise abnormal from original malformation or arrest in its development, or when it has become perforated by ulceration, condensed and shrivelled by dis- ease, or partially destroyed by gangrene. The mucous membrane of the velum and adjacent surfaces enjoys a certain degree of taste for peculiar substances, and is also exquisitely sensible to certain pungent, disagreeable, and noxious odours, and the irritability of all the sur- rounding muscles is thereby rapidly excited, through the reflex power of the nervous system, to active and repeated contractions, not so much in their ordinary as in a retrograde order, so as to lead to the rejection or expulsion, aided by forcible expiration, of the offending sub- stance, and thus by this endowment the lungs and stomach are won- derfully guarded against the admission of injurious or dangerous agencies. In these various offices of the velum, it is not easy to affirm the use of the uvula ; its muscle may stiffen and strengthen it when the palate is raised or tense, or when the latter is depressed, it may in a passive manner contribute to narrow the chink-like passage for the food ; however its variable and even occasional arrest of develop- ment, and not unfrequent removal in man without any corresponding deficiency, together with its total absence in most of the animal king- dom, preclude the idea of its being of any essential utility in a function so universal as is that of deglutition ; it may, no doubt, aid the velum in perfecting those modulations and expressions of voice already alluded to. It is very sensible to contact, and irritable, and all the sin-rounding parts very quickly sympathize with it ; from its depending position and the proximity of its apex to the base of the tongue, not even the thinnest stratum of fluid can glide between the two, without exciting the sensibility of the uvula, and thence the irritation is rapidly conveyed to all the muscles concerned in the second stage of deglutition ; it thus IH'BI.IN DISSEC'TOU. DO appears to act as a sort of sentinel in this important and critical posi- tion, and as deglutition of the salivary secretions constantly occurs at intervals during sleep, which man usually enjoys in the horizontal or reclined position, it may not, perhaps, be amiss to conceive that the superior development of this appendix in him has reference to that condition. A careful examination of all this curious and complicated palatine and pharyngeal apparatus will explain the mechanical arrangements which have been so ingeniously designed and so perfectly executed for the safe and frequent performance of functions so necessary to life ; how Fig. 11.* the air can freely pass, during sleeping as well as waking hours, to and from the lungs, as also into each tympanum, without descending into the stomach, and how all alimentary matters, solid as well fluid, are in safety propelled over the glottis into the oesophagus by the rapid, con- vulsive efforts of numerous concurring muscles, with only a momentary interruption to respiration, as this function, that is, the mechanical acts of inspiration and expiration, must be suspended during the in- stant in winch the second stage of deglutition is being performed. The soft palate and its arches, the uvula and the tonsils, are liable to many morbid affections, viz., acute inflammation and all its con- sequences ; syphilitic ulceration very commonly attacks these parts, particularly that surface towards the mouth ; polypi, also, are not un- * The muscles of the soft palate. 1. A transverse section of the skull, passing through the basilar process of the occipital bone in the centre, and through, 2. The posterior part of the great wing of the sphenoid. 3. The vomer covered by mucous membrane, and forming the posterior part of the septum of the nasal fossae. 4. The posterior nares. 5. The Eustachian tube. 6. The levator palati muscle. 7. 7. The tensor or circumflexus palati. 8. 8. The hamular process, round which the tensor palati turns. 9. The horizontal portion of the tensor palati, expanding in the structure of the soft palate. 10. The motor uvulae de- scending from the posterior spine of the palate bones. Ob DUBLIN DISSECTOR. frequently produced from the velum, and in general from its upper or nasal surface. When the uvula is the seat of inflammation, its pendu- lous extremity becomes so distended by serous infiltration that its figure is totally changed, and it sometimes interferes so much with deglutition and respiration, or excites such irritation, as to require free scarifica- tion, or excision of its lower portion. The velum is sometimes found cleft at birth with or without the accompanying similar abnormal state of the hard palate and upper lip. The tonsil is very subject to acute inflammation (cynanche tonsil- laris) ; in this affection it enlarges so much as to impede deglutition, induce deafness, and even in some cases to threaten suffocation. It is sometimes, also, the seat of chronic enlargement, to such a degree as to require the operation of removal ; it is also frequently affected with syphilitic ulceration, also with calcareous deposit : its cribriform surface, when covered with lymph, should not be mistaken for ulceration. The oesophagus appears as the continuation of the pharynx, it dif- fers from it, however, in structure ; the mucous membrane is paler, and thrown into longitudinal folds ; the muscular fibres are arranged in two lamina?, the external are longitudinal, strong, and red, attached superiorly and anteriorly to the cricoid cartilage, and below are lost on the stomach ; the internal circular fibres are pale, and cease abruptly at the cardiac orifice of the stomach. In the neck the oesophagus de- scends posterior to the trachea, and nearly in the middle line ; it in- clines a little to the left side below, so as to be uncovered by that tube ; in the upper part of the thorax it inclines a little to the right, and below again to the left. Tliis slightly tortuous, intestine-like course might offer some impediment to the passage of a bougie : the left lobe of the thy- roid gland, the recurrent nerve, and the inferior thyroid vessels, lie on it in this situation ; it is flattened in the neck, and rounded in the back, is wider below than above. The morbid appearances met with in the pharynx and oesophagus are not very many ; the mucous membrane of the former is liable to inflammation (cynanche pharyngea), and to iilceration from various causes ; the submucous tissue is frequently the source of polypous growths, particulai-ly at the upper part. The lining membrane of the O3sophagus is seldom the seat of active inflammation, except as the consequence of some foreign body, or the contact of some acrid sub- stance ; it is not unfrequently the seat of stricture, caused in some cases by a contraction and thickening of its coats, in others by true scirrhus, ending in cancerous ulceration ; tumours in the vicinity of this tube will also interrupt its functions, for example, bronchocele, enlarged bronchial glands, or aneurism of the descending aorta. The oesophagus is also sometimes affected with paralysis, and in hysterical patients it is very subject to nervous affections, which frequently bear a close resemblance to true stricture of this tube. The course and con- nexions of the oesophagus in the chest will be seen hereafter.* * The student should practise the passing of a probe or canula armed with a ligature, along the nares, into the pharynx, and endeavour to enclose the uvula 57 SECTION VI. DISSECTION OF THE LARYNX. THE larynx surmounts the upper extremity of the respiratory pas- sages with which it communicates below, as it does with the pharynx above ; it is composed of a complicated apparatus of several cartilages, muscles, and ligaments, which constitute the organ of voice; is placed at the anterior part of the neck, between the tongue and trachea, in front of the pharynx and oesophagus, covered only by the integuments and the subhyoidean muscles ; it is suspended by muscles and liga- ments from the os hyoides. Although this bone does not, strictly speaking, appertain to the larynx, but rather to the tongue, yet the former is so connected with it, that this appears a fitting situation to examine it. The os hyoides is connected to the chin by several muscles, and to the styloid process of the temporal bone on each side by the digastric and stylo-hyoid muscles and ligament ; it consists of five parts, the middle portion, or body, is very rough, and convex anteriorly and su- periorly for the attachment of muscles, concave posteriorly and infe- riorly, where it covers the epiglottidean submucous tissue ; from the body the cornua pass off, one to either side, giving attachment to mus- cles above and below, and lined by mucous membrane ; they serve to expand the pharynx and fauces ; where each cornu joins the body a small process, the appendix, ascends obliquely backwards, and gives attachment to the stylo-hyoid muscle and ligament. It sometimes happens that this ligament is ossified, so that the os hyoides will then be found attached to the cranium. In examining the different structures which enter into the forma- tion of the larynx, I shall pin-sue the following order : 1. the carti- lages, with their ligaments and articulations ; 2. the muscles ; 3. the mucous membrane and glands ; 4. the vessels ; 5. the nerves ; and, finally, offer a few general observations on this organ. Four true, or in the noose, thus imitating the operation of tying polypi when situated in the pharynx, on the velum, or in the posterior nares ,- he may also pass a flexible tube into the pharynx, and thence direct it to the stomach or into the larynx. Any practitioner may be suddenly called on to use the stomach pump in case of poison having been swallowed, or to inflate the lungs in asphyxia , in the first case, when the tube has passed into the pharynx, from the mouth or nares, the tongue should be pi'essed back, so as to close the glottis, and the end of the in- strument should be kept close to the vertebrae to avoid irritating or pressing on the epiglottis ; in the second case, the tube should be passed through either naris into the pharynx, the forceps or the finger of the surgeon, introduced into the mouth, can then guide it downwards and forwards to the glottis ; at this time, however, the tongue should be drawn forwards; thus the epiglottis will be raised, and the glottis opened opposite the edge of the-velum ; the tube may then be urged into the larynx, and artificial respiration commenced. In conducting this process it is advisable to press the upper part of the trachea gently against the vertebrae, so as to fix the larynx and the tube, as well as to guard against the admission of air into the oesophagus, and the consequent inflation of the sto- mach. 58 DUBLIN DISSECTOR. Fig. 12.* perfect, and four false, or imperfect, cartila- ges, enter into the formation of the skeleton of the larynx : the true cartilages are the thyroid, cricoid, and two aryte- noid ; the false cartilages are the two cor- pora cuneiforma, and the appendices or cornicula of the arytenoid cartilages ; there is also one fibro-cartilage, the epiglot- tis. The thyroid, or shield-like cartilage, is placed at the anterior and lateral parts of the larynx; it embraces the sides and back part of the cricoid, and protects the greater part of the mechanism of the la- rynx, but is open behind ; it is composed of two broad, irregularly shaped lateral plates or alse, which join in an anterior angle or prominence in the mesial line ; this is more developed in man than in the female or child, and is named the Pomum Adami. As each ala passes backwards it increases in depth, and presents two tubercles, one near the superior, the other smaller near the inferior margin ; an oblique ridge connects these, and divides the ala into two unequal segments, of which one is anterior and superior, and much larger than the other, which is be- hind and below this line. This ridge gives attachment to the sterno- thyroid, hyo-thyroid, and inferior constrictor muscles ; near the upper tubercle is a notch, or often a foramen, for the transmission of the su- perior laryngeal nerve. The upper border of each ala is convex, and gives attachment to the thyro-hyoid membrane ; it is deeply notched in front above the pomum. The inferior border is shorter, and nearly horizontal, and projected a little below the pomum, giving attachment to the elastic crico-thyroid ligament ; posteriorly this border is arched deeply. The alae are round and thick posteriorly, giving attachment to muscles and the mucous membrane of the pharynx, and resting against the vertebral column : from the upper and lower edge of each are continued the cornua. The superior or ascending cornua are long and round, and are connected to the os hyoides by round ligaments, which are often studded with cartilaginous and osseous grains. The inferior cornua are short, and bent a little inwards and forwards, and are articulated to the oblique surfaces on the cricoid cartilage. Each ala is concave internally, and covers the thyro -arytenoid, and the la- teral crico -arytenoid muscles. The posterior surface of the pomum is * A lateral view of the larynx, the muscles having been removed. 1. The body of the os hyoides. 2. Its appendix or lesser comu. 3. Its great cornu. 4. The superior extremity of the epiglottis. 5. The hyo-thyroid ligament or mem- brane. 6. The thyroid cartilage. 7. The cricoid cartilage. 8. The upper part of the trachea. in r.i.ix I>IX>KCTOK. 59 very concave, and gives attachment in tin- mesial line to the ligament of the epiglottis, ami on each side to the chorda} vocales. The cricoid or annular cartilage forms the lower part or base of the larynx, it is very thiek and strong ; it is not perfectly circular, but rather elliptical, narrow before, deep and strong behind; the inferior edge or circumference is nearly circular and horizontal, and connected by an elastic structure and mucous membrane, to the first ring of the trachea, than which it is thicker and deeper. The anterior and external surface is convex, and gives attachment to the crico-thyroid muscles, posterior to which is an articulating tubercle on each side for the in- ferior cornu of the thyroid cartilage. The superior margin is oblique, being bevelled from below and before, upwards, backwards, and a little inwards ; anteriorly there is a space between this border and the thy- roid cartilage, occupied by the elastic crico-thyroid ligament ; the pos- terior part of thi.s upper margin is horizontal, having on each side a smooth convex surface, looking upwards and outwards for articulation with the bases of the arytenoid cartilages. The posterior surface is nearly four times deeper than the anterior, and is divided by a middle vertical prominent ridge, to which some fibres of the oesophagus are attached ; on each side of this is a depression which is occupied by the crico-arytenoid postici muscles. The internal surface of this cartilage is smooth, and lined by the mucous membrane. The arytenoid, or ewer- shaped cartilages, are situated vertically on the articulating surfaces on the upper and posterior border of the cricoid ; they are somewhat pyramidal or triangular ; the Fig. 13.* base of each is below deeply curved into an oval, oblique, articulating surface, with two processes, one external for the attachment of the crico- arytenoid muscle, the other is anterior, for the insertion of the inferior chorda vocalis, which forms the side of the rima glottidis ; this latter prominence is pyramidal, it projects consider- ably over the side of the rima, nearly one- third of its extent. The apex of each arytenoid inclines a little backwards, and is surmounted by the appendix or corniculum. The posterior surface is concave, and covered by the arytenoid muscle. Anteriorly each is convex, with sharp, rugged ridges for the insertion of the superior chorda vocalis, and the aryteno-epiglottictoean folds of mucous mem- brane which form the side of the glottis ; these ridges are, of course, superior to the basilar projections into which the inferior chordae * A posterior view of the larynx, after the removal of its muscles. 1. The posterior surface of the epiglottis. 2. 2. Appendices or lesser comua of the os hyoides. 3. 3. The great cornua of the os hyoides. 4. 4. The posterior surface of the hyo-thyroid ligament. 5. 5. The posterior surface of the thyroid carti- lage. 6. 6. The ascending cornua of the thyroid cartilage. 7. 7. Its inferior cornua. 8. The cricoid cartilage. 9. a. The arytenoid cartilages. 10. The first ring of the trachea. 60 DUBLIN DISSECTOR. Fig. 14.* vocales are inserted. Their internal or opposed sides are flat and smooth, and covered by mucous mem- brane, so as to admit of their approxi- mation. These cartilages enjoy free motion in the four directions, forwards, backwards, inwards, and outwards, as well as a certain degree of rotation round the axis of their articulations on the cri- coid. The appendices or cornicula of the aiytenoids are two small, curved, cartila- ginous bodies, described by Santorini, inclining backwards and towards each other, loosely joined to the apex of each arytenoid, which they serve to lengthen in the vertical direction, and on which they can freely move. The epiglottis stands behind, the base of the tongue, nearly erect, in front of the opening of the glottis, over which it can, however, be bent almost horizontally, so as to cover this opening during degluti- tion. It is considered as a fibro-cartilage, but it is really a complex struc- ture, and may be regarded as one sui generis ; in form it is somewhat triangular or oval, its edges being curved or curled, so as to resemble a cordate leaf ; its colour is a pale yellow, with little appearance of vas- cularity ; anteriorly it is curved forwards above and a little along its edges, so as to be concave from above downwards, and convex transversely, while posteriorly it is convex from above downwards, and concave transversely. The anterior or lingual surface is free su- periorly, and can be seen and felt in the li ving mouth ; inferiorly this surface is adhering to the base of the tongue, os hyoides, and thyroid cartilage ; to the tongue by an elastic tissue, glosso-epiglottic liga- ment, which is below the mucous fraenum ; to the os hyoides by a thin ligament (hyo-epiglottic), extending from the upper and posterior edge of the base of that bone to the forepart of the epiglottis, and beneath this by a mass of cellulo-adipose matter of a yellowish colour, very soft, mobile, and somewhat elastic, and surrOunded by loose cellular * A vertical section of the larynx, exhibiting the interior of the left half. 1. A portion of the base of the tongue. 2. The section of the body of the os hyoides. 8. The frsenum epiglottidis. 4. The left half of the epiglottis. 5. The aryteno- epiglottidaean fold of mucous membrane. 6. A section of the epiglottidean gland. 7. The great cornu of the os hyoides. 8. The hyo-thyroid ligament. 9. The ascending cornu of the thyroid cartilage. 10. The mucous membrane of the pharynx. 11. The cavity of the oesophagus. 12. A section of the thyroid car- tilage. 13. The superior vocal chord. 14. The sinus or ventricle of the larynx. 15. The inferior vocal chord. 16. A prominence produced by the left aiytenoid cartilage. 17.17. Sections of the cricoid cartilage. 18. The internal surface of the cricoid cartilage, lined by mucous membrane. 19. The internal surface of the trachea. 20. A section of the thyroid gland. 1HT.I.1N l>ls>K transverse fibres, the former are superficial and consist of two or three fasciculi which pass from the apex of one cartilage to the base of the opposite ; the transverse fibres are anterior to the former, more nume- rous, and are attached to the posterior surface of each cartilage. Use, to approximate these cartilages, and close the sides of the riraa posteriorly: at the same time that they tend to separate their anterior processes, and tints can open the rima in front ; these, together with the thyro and crico-arytenoid laterales, are the contractors of the rima glottidis. In the aryteno-epiglottidean folds, fleshy fibres are sometimes discern- able, and have been described as distinct muscles, and named, from their situation, aryteno-epiglottidean, and thyro-epiglottidean, or the depressors of the epiglottis. In the human subject these are seldom sufficiently well marked to merit the appellation of distinct muscles. We shall, however, describe them as they are occasionally to be found. Timio-EpiGLOTTici are situated between the thyroid cartilage and the epiglottis ; arising from the internal surface of the angle of the thyroid, the fibres pass upwards and forwards to the base of the epi- glottis, and are inserted into it, behind the thyro-epiglottidean liga- ment ; the action of these fibres will be to depress the epiglottis. Tiie AnvTKxo-EpiGLOTTici arise from the apices of the aiytenoid cartilages, and the membrane around them, pass fonvards and upwards to the sides of the epiglottis, and the adjacent folds of mucous mem- brane ; the action of these fibres must be nearly similar to that of the former. Mr. Hilton has described an inferior aryteno-epiglottidean muscle, as arising from the arytenoid cartilage, just above the chorda? vocales, thence expanding fonvards and upwards, over the sacculus laryngis, and inserted broad into the side of the epiglottis ; its action he con- cludes to be, to compress and alter the form of this pouch, diminish its cavity, and compress the adjacent submucotis glands. The group of laryugeal muscles now described are exceedingly com- plex, and then- actions, individually and collectively, by no means easily understood. The articulations between the thyroid and cricoid cartilages, and the arytenoid, allow of such varied and composite motions, and the rima glottidis is so differently affected by each, even by the slightest alteration in the chordae vocales, that it is difficult, if not impossible, to appreciate the influence of each individual muscle ; neither can we suppose that any such isolated action occurs during life, but, on the contrary, in every vocal exertion it is more than pro- bable all these muscles are in a state of action, and by that har- monious consent and sympathy which is every where maintained in groups of muscles associated for one common purpose, they mutually adjust their states of action and of relaxation, in such nicely balanced proportions, as to produce the effect required, and that this exquisite de- gree of arrangement is acquired by an education and practice of the muscles, of which the will is scarcely cognizant ; for although thesi- muscles are, to a great extent, voluntary, and belong to the system of 66 DUBLIN DISSECTOR. animal life, yet the will has not perfect control over their individual ac- tions, neither can it separate those of one side from the opposite ; nay, those fibres which are connected with the epiglottis, and which probably minister to the function of deglutition rather than to that of voice, appear wholly from under the influence of the will, and act in that spasmodic or convulsive motion, by which the food is hurried over the glottis and precipitated into the oesophagus. The mucous membrane of the larynx is continued from that of the mouth, nose, and pharynx ; it is soft, smooth, and of a delicate rose colour, the tint differing in different situations ; it encloses both the anterior and posterior surfaces of its back part, descends into it, covers every irregularity of the surface, lines every depression, and is con- tinued through the trachea and bronchial tubes into the vesicular struc- ture of the lungs, thus constituting the anterior division of the great internal or gastro -pulmonary mucous membrane. As this membrane passes from the tongue to the epiglottis, it forms three folds which serve to connect the latter to the former, of these three glosso-epiglottic folds the centre or fraenum is the principal ; is continued all round the free surface of the epiglottis, and covers the entire of its pos- terior or laryngeal aspect ; is reflected from its edges to the arytenoid cartilages, forming the aryteno-epiglottic folds or lateral boundaries of the opening of the glottis or larynx, these enclose some ligamentous fibres ; as it descends it covers the chordae vocales, lines the ventricles and sacculi laryngis, and the adjacent muscles, and finally becomes the lining coat of the trachea. It is perforated by numerous minute holes, the orifices of mucous ducts ; the submucous tissue at the upper part is loose, and quickly admits of infiltration and swelling, or oedema, dur- ing inflammation, but below, as well as in the trachea, it is less in quantity, and of a more dense quality, therefore, inflammation is not succeeded so rapidly by submucous effusion, as it is by exudation of lymph upon its surface. Several mucous glands are connected with this membrane, the principal are to be found in the immediate vicinity of the ventricle and sacculus laryngis, and in the ary teno-epiglottidean folds of mucous membrane ; these latter are not to be confounded with the cuneiform cartilages which also occupy this situation, and were looked upon by some as glandular. The epiglottidean gland or body, situated in front of the epiglottis, behind the os hyoides, and beneath the hyo-epi- glottidean ligament, has been already considered. Some describe, but most probably incorrectly, the porous appearance presented by the laryn- geal surface of the epiglottis, as derived from the orifices of its ducts. The openings of the larynx are two, the superior or the glottis, and the inferior or the tracheal. Intermediate, and nearly midway within the larynx, is a very remarkable slit-like narrowing of its cavity, named the rima of the glottis or larynx, this is occasionally, but certainly inaccu- rately, called the lower opening of the larynx, to distinguish it the more certainly from the upper extremity or the glottis ; the rima, however, is by no means the lowest part of the organ ; it is the narrowest portion of D! I'.I.IN DISSECTOR. (he air tube, and is tin- scat of the vocal function. The superio or the glottis is at the lower and anterior part of the pharynx, behind the epiglottis, and rather beneath the tongue ; it is of a triangular form, the base anteriorly formed by the epiglottis; the sides are composed ,,f tlu- aryteno-epiglottidcan folds of mucous membrane, and the apex, which is posteriorly notched or bifid, is formed by the appendices of the arytenoid cartilages. The sides are somewhat thickened and strength- ened by the enclosed cartilages or bodies : the aspect of this opening is upwards and backwards ; when dilated it is the widest part of the tube ; it is momentarily, but perfectly, closed during deglutition ; its size and form, therefore, admit of every variety of change. The inferior opening of the larynx is always free, and nearly a per- fect circle, formed by the lower border of the cricoid cartilage, which is connected and continuous with the trachea : its size or figure cannot be altered by position or muscular action. The rima glottidis is an horizontal, slit-like passage, about three quarters of an inch below the glottis, bounded posteriorly by the mu- cous membrane connecting the bases of the arytenoid cartilages, and which covers a portion of the anterior surface of the arytenoid muscle, laterally by the chordae vocales, chiefly the lower and by the inner side of the bases of the arytenoid cartilages, and their anterior processes, and an- teriorly by the angle of the thyroid. We might regard the rima as double, one placed horizontally above the other; the upper one, between the upper or false chordae vocales, wide, and not so distinct as the lower or true rima, which is between the true vocal chords, and which is nar- row, distinct, and sharp ; the form of this true rima in a state of repose appears, on a superficial view, to be triangular, but on closer examina- tion it will be found contracted behind the centre, and in fact may be described as consisting of three distinct parts, an anterior, middle, and posterior. The anterior is the space enclosed between the true chorctee vocales, and extends from the angle of the thyroid to the anterior spurs of the arytenoids, the middle corresponds to the interval between the anterior thin edges of the arytenoid cartilages, and is the narrowest ; the posterior is bounded by the internal sides of the bases of the arytenoid cartilages and the semilunar fold of mucous membrane, before alluded to as forming the posterior boundary of the rima ; of these three spaces, the anterior is the most extensive, and of a compressed elliptical form ; the antero-posterior diameter of this portion is often considerably increased by an excavation in the pomuni Adami, or angle of the thyroid cartilage ; this excavation is very remarkable in some of the larger ru- minants. The middle division of the rima is the smallest, and the posterior is triangular, with an arched base, so that the three spaces, taken together, resemble the steel of a halbert in shape. The form of this opening, however, is variable, and depends on muscular action, as during every act of respiration, voice, or speech, it is subject to change in shape and size ; thus in ordinary breathing it dilates during inspi- ration, and contracts in expiration. If the lateral crico-arytenoid mus- cles are alone thrown into forcible action, the arytenoid cartilages are F2 68 DUBLIN DISSECTOR. rotated upon their articulations, so as to cause their anterior edges and spurs almost to meet, and thereby nearly divide the rima transversely into two unequal openings. The muscular action which appears most completely to dilate the rima, is the joint action of the crico-arytenoid laterales and postici, the former having the power of drawing the car- tilages forwards and outwards, the latter backwards ; the two forces will act in the diagonal, which is backwards and outwards, and so con- vert the rima into a lozenge-shape with unequal sides, the two anterior being longer than the posterior. The muscles which appear most com- pletely to close the rima, are the arytenoid and thyro-arytenoid acting in conjunction ; the former approximate the bases of the arytenoid, and the latter, causing the chordae vocales to meet, at the same time prevent the anterior edges of the arytenoids being turned outwards, a motion which, we have seen, the unassisted action of the arytenoid accomplishes. Immediately above the true chordae vocales, the larynx presents, on each side, a lateral dilatation called the ventricle or sinus of the larynx ; this elliptical space is bounded above by the semilunar folds, before alluded to under the name of the superior or false chordae vocales ; the mucous membrane lining these cavities presents numerous small glands, the mucus from w r hich is constantly expressed by the action of the thyro-arytenoid muscle, which forms the outer boundary of this space. From each ventricle of the larynx the mucous membrane is prolonged upwards in a thimble-like form, constituting a pouch or cul de sac, first noticed by Morgagni, also described by Cruveilhier, and more recently by Mr. Hilton,* under the name of sacculus laryngis; it com- municates with the ventricle by a narrow valve-like opening, extends upwards and forwards between the superior chorda? vocales and the ala of the thyroid cartilage to a variable distance in different individuals ; in some these sacs are small, and even indistinct, whereas in others, they ascend as high as the upper border of the thyroid cartilage, and in front of the epiglottis, so that two probes, introduced into these cavities, can be carried so far forwards and inwards as almost to meet in front of the latter : this, however, is by no means a constant con- formation. Each sac is lined by a thin membrane, and covered by the aryteno-epiglottic and thyro-epiglottic muscular fibres ; many mucous glands open on its surface, the secretion of which serves to lubricate the chordaB vocales. The arteries which supply the larynx are derived from the superior and inferior thyroid, the former is a branch of the external carotid, the latter of the subclavian, the accompanying veins open into the ad- jacent venous trunks. As the surface of the larynx possesses exquisite sensibility, and its muscles execute delicate and complex actions, it requires a proportiona- bly free supply of nerves. The laryngeal nerves are four in number, two on each side, the superior and inferior, or the recurrent nerves ; both are derived from the par vagum or pnetuno-gastric, the former arises * Guy's Hosp. Reports, No. V. G9 near the base of the cranium ; the latter, on the right side, arises in the lower part of the nock, and on the left in the thorax, below the arch of the aorta. The superior nerve first sends some filaments to the pharyngeal plexus, and to the lower part of the pharynx; next to the thyro-hyoid muscle, and to the thyroid gland ; it enters the larynx either above the thyroid cartilage, or by a foramen in its ala, and then sends its principal branches to the mucous membrane around the epiglottis, also some to the arytenoid muscles, to the thyro-arytenoid, and crico-arytenoid lateralis ; a long filament also to the crico-thyroid muscle, and descending filaments to anastomose with the recurrent. The inferior laryngeal nerve first gives off several car- diac branches, some to the trachea, oesophagus, and pharynx, and finally is lost in filaments wlu'ch supply the crico-arytenoideus posticus, arytenoidei, crico-arytenoideus lateralis, and thyro-arytenoideus, and also anastomose with the superior nerve. The precise functions of each of these nerves it is difficult to ascertain ; it is probable they are each compound nerves, that is, both motor and sensitive, but in inverse pro- portions ; the superior partakes of the sensitive endowment much more than the inferior, which is eminently motor, as may be inferred from the distribution of its branches being almost wholly to the muscles, and which opinion has been confirmed by experiments. Sensibility is more exalted at the upper than at the lower part of the larynx, with the obvious design of affording protection to the air passages against the admission of any noxious gas or foreign substance ; and here, accord- ingly, the mucous membrane is largely supplied by the sensitive por- tion of the superior laryngeal nerve, which, from its connexions with the pharyngeal plexus, and thereby with the glosso-pharyngeal, pneu- mo-gastric, and sympathetic, will most intimately associate the appa- ratus for deglutition with this particular part of the larynx, while again the connexion between the superior and inferior laryngeal nerves maintains that sympathy, which, between the several parts of so com- plex an apparatus, must be necessary to the due exercise of the func- tions of the whole. An extensive range of sympathetic connexions, interesting to regard in health, and important to reflect upon in disease, is main- tained between the organ of voice, and the great vital functions of digestion, respiration, and circulation, through the medium of the laryngeal, cardiac, pulmonary, resophageal, and gastric branches of the eighth pair, all of which are still further associated, not only with one another, but also with the great nervous centres, by their common and frequent communications with the great sympathetic or ganglionic system in the neck, in the chest, and in the abdomen. The reflex property of the nervous system is well exemplified in these nerves, as impressions made on the sensitive surface, and reflected to the medulla oblongata, are thence rapidly propagated to the motor nerves. The muscles of the larynx must be considered as belonging to the mixed rla>s; in the production of the voice, with its various modifications, they are wholly under the influence of the will, and their actions are i() DUBLIN DISSECTOR. improved by age, by practice, and by education ; but in deglutition, in spasmodic closure, and in the respiratory movements, the dilatation, and contractions of the glottis, corresponding to inspiration and expi- ration, and the design of which is to oppose the very contrary tendency in the current of air to and from the lungs, in all these, and in many other conditions, these muscles are wholly involuntary. (For a more par- ticular description of these nerves, see Par Vagum, in Nervous System). The larynx in the male is better developed than in the female ; the angle of the thyroid cartilage, the base of the os hyoides, and the an- terior segment of the cricoid, are all much less prominent in the latter. In the infant it is proportionately small, the cartilages are weak, the chordae vocales by no means strong and shining, the ventricles and laryngeal sacs scarcely visible, whereas the base of the os hyoides is large and prominent. The larynx undergoes but little change during the years of infancy and youth, and does not increase in the same ratio as other parts of the body ; but at puberty, coeval with the changes in the reproductive organs, it is rapidly developed, so that in the course of a year it loses the infantine, and acquires the adult character, either male or female. Ossification commences at uncertain ages, sel- dom before thirty-five or forty years, but occasionally much earlier ; it occurs first in the thyroid, next in the cricoid, and latest in the aryte- noid cartilages, and is always more perfect in the male than in the female. The larynx and trachea are subject to many morbid changes, of which the mucous membrane is most commonly the seat : inflamma- tion of that lining the larynx is named cynanche laryngea, or laryn- gitis ; of that lining the trachea, cynanche trachealis, or croup ; in the latter case an exudation of lymph, or a false membrane, is usually formed in the trachea, in the former case, effusion of serum in the loose submucous tissue, or oedema of the glottis, is a frequent and often fatal effect ; ulceration, the effect of inflammation, is not uncommon about the glottis, also diffuse inflammation ending in sloughing of the mucous and submucous tissues ; syphilis and phthisis, too, occasionally induce ixlceration in this part, and even involve the epiglottis and the aryte- noid cartilages. All the cartilages, except the epiglottis, especially in men, are very prone to ossification ; this can scarcely be regarded as disease ; these bodies are also liable to inflammation, softening, ulcera- tion, and change of form ; the epiglottis is occasionally shrivelled and contracted, and even completely separated and discharged externally, or almost wholly absorbed, and yet deglutition may continue unim- paired. The articulations, particularly the crico-arytenoid, are subject to the same morbid changes as other synovial membranes ; the muscles, without undergoing any obvious abnormal change in structure, are particularly liable to dangerous spasmodic affections, also to gout, rheumatism, and paralysis. Foreign bodies impacted in the lower part of the pharynx, or when engaged in the larynx, or when fallen into the trachea, may cause such suspension of respiration as to call for the operation of bronchotomy ; suspended animation, also, from any cause, or any tumour in the fauces which impedes respiration, may require Dl'BMN I>I>M:< foil. 71 the same nu-ans ; this operation i,s two-fold, laryngotomy and tracheo- tomy : in the tirst the air tube is to be opened through the crico-thy- roid ligament, hi the second through the fourth, fifth, and sixth rings of the trachea. SECTION VII. DISSECTION OF THE DEEP MUSCLES OF THE NECK. THESE muscles, which are seven in number on each side, form the third layer of the cervical muscles ; they lie close to the vertebrae, and are exposed by removing the pharynx, larynx, cervical vessels, and uerves. Fig. 18.* * The deep muscles of the neck. 1. A transverse section of the base of the skull. 2. The body of the seventh cervical vertebra. 3. The body of the first dorsal vertebra. 4. The longus colli muscle. 5. 5. The scalenus anticus muscle. 6. 6. The scalenus medius. 7. 7. The scalenus posticus. 8. The rectus capitis anticus major, drawn aside to shew, 9. The rectus capitis anticus minor. 10. The rectus capitis lateralis. 11. The first cervical inter-transversalis. If DUBLIN DISSKCTOB. LONG us COLLI extends from the third dorsal vertebra to the atlas ; it arises from the sides of the bodies of the three superior dorsal, and four inferior cervical vertebrae, from the intervertebral ligaments, also from the head of the first rib, and from the anterior tubercles of the transverse processes of the four last cervical vertebrae ; the fibres ascend obliquely inwards, adhering to each bone in their course, and are in- serted into the forepart of the first, second, and third cervical vertebra-. Use, to bend the neck to one side, and rotate the atlas on the clenta- tus ; or, if both muscles act, to strengthen and steady the neck, or to bend it directly forwards. This muscle appears to consist of an in- ferior and superior portion ; the first, arising from the bodies of the dorsal, is inserted into those of the inferior cervical vertebrae ; the se- cond, arising from the transverse processes of the third, fourth, and fifth cervical vertebrae, is inserted into the bodies of the first and se- cond. These muscles, like most of those which adhere to the vertebra?, though long, yet consist of short fibres which pass from one bone to another, are generally intermixed with tendinous substance, and are irregular as to the number of the vertebrae to which they are attached. The pharynx, oesophagus, sheath of the cervical vessels and nerves, are loosely connected to them in front. RECTUS CAPITIS ANTIOUS MAJOK, long and flat, thick above and narrow below, arises by small tendons from the anterior tubercles of the transverse processes of the four last cervical vertebra? ; they soon unite in a fleshy substance, which ascends obliquely inwards, and is inserted broad into the cuneiform process of the occipital bone. Use, to bend forwards the neck and head. This muscle lies behind the carotid artery and sympathetic nerve, and between the longus colli and scaleni, overlapping the former. Separate this muscle from its insertion, and we expose the following : RECTUS CAPITIS ANTICUS MIXOK, short and narrow, arises from the transverse process of the atlas, ascends inwards, and is inserted into the cuneiform process. Use, to bend the head forwards, and to one side, on the atlas ; this muscle lies to the outer side, but is in part concealed by the last, and by the superior ganglion of the sympathetic, it lies on the atlanto-occipital articulation. RECTUS CAPITIS LATERALIS, very short, arises from the transverse process of the atlas, ascends, and is inserted into the semilunar ridge or jugular process of the occipital bone, which extends from the con- dyle to the mastoid process. Use, with the last muscle it can bend the head forwards or incline it to one side. This muscle is external to that last described ; it lies on the vertebral artery, and is covered by the jugular vein. SCALENUS Avncus, at the root of the neck, in part continuous with the rectus anticus major, simple and broad below, but divided into slips above, arises tendinous from the anterior tubercles of the trans- verse processes of the third, fourth, fifth, and sixth cervical vertebrae ; the fibres descend obliquely forwards and outwards, form a flat muscle, which is inserted tendinous into the upper surface of the first rib, near nnu.iN DISSECTOR. 73 its cartilage. I'm'. t<> In-nd the neck forwards and laterallv. al>o t" elevate and lix tin- rik as in inspiration. The phrenic nerve descends on the anterior surl'ace of this muscle; the subclavian vein crosses its insertion : the transverse cervical vessels, the omo-hyoid and sterno- niastoid muscles, lie anterior to it ; the subclavian artery and brachial plexus are behind it. and the vertebral vessels separate it from the longns colli. S(. \i.i..\rs 3lKi>irs, larger and longer than the last, arises from the posterior tubercles of the transverse processes of four or five inferior cervical vertebnv, by small tendinous libres ; these become fleshy, de- >eend obliquely outwards and backwards, and are inserted into the upper surface of the first rib, behind the subclavian artery. Use, similar to the last. Tin's muscle is covered by the brachial plexus, sub- clavian artery, and anterior scalenus. ScAi.Kxrs POSTICTS arises from the posterior tubercles of tAvo or three lower cervical vertebrae, descends behind the former, and is in- serted into the upper edge of the second rib, between its tubercle and angle. Use, to elevate the second rib, to bend the neck to one side, and a little backwards. One or two branches of the brachial plexus sometimes separate this from the middle scalenus, at other times there is no distinction between them, excepting in their insertion ; behind the j iosterior scalenus lie the transversalis and splenius colli, also the leva- tor anguli scapulae, which muscles cannot be examined at present. We shall next proceed to the dissection of the thorax. 74 DUBLIN DISSECTOR. CHAPTER III. DISSECTION OF THE THORAX. SECTION I. OF THE MUSCLES ON THE ANTERIOR AND LATERAL PARTS OF THE THORAX. THE thorax, or chest, is the middle division of the body, continuous with the neck above, and abdomen below ; it contains the impor- tant organs of respiration and circulation, and serves as the basis of support and of attachment for the upper extremities ; it presents an anterior or sternal, a posterior or dorsal, and two lateral or costal re- gions. Make one incision through the integuments along the clavicle, a second from the upper end of the sternum to the ensiform cartilage, and from this point carry a third towards the shoulder ; reflect the integuments and subjacent cellular membrane from within and from below, upwards and outwards, and thus the great pectoral muscle will be exposed, the dissection of which will be facilitated if its fibres be made tense by separating the arm from the side.* The integuments are thicker mesially than at either side, and more so in the male than in the female ; in the former also they are more or less furnished with hairs. The superficial fascia is very variable, it adheres to the sternal and sterno-costal ligaments, but laterally is more loose and laminated ; its deeper layer adheres to the pectoral muscle, continuous above with the superficial fascia of the neck, and below with that on the abdomen; near the epigastrium it is more dense, and binds down the recti mus- cles. The anterior region of the chest may be divided into three, the middle or proper sternal, and the two lateral or mammary regions ; in the adult female these latter are of more importance, as they con- tain the mammary glands, which may now be examined. The MAMMAE, or BREASTS, are conglomerate glands, sympathizing in a remarkable manner with the uterus, and designed to secrete the * The student of some experience, instead of removing the skin from this re- gion, according to the above directions, may rather practise the operation of extirpation of the breast, which can be easily accomplished by two semielliptical incisions, one below, and the other above the gland, through the integuments, and nearly parallel to the fibres of the great pectoral muscle, from which the gland can be then easily detached, unless disease should have caused any very close adhesion. IH'HUN DISSIXTOK. 75 milk, that fluid which is to serve for some time as the nutriment for the infant. The importance of these orgau> is shewn by the fact of a very large division of the animal kingdom being named, from their existence, " Mammalia ;" this common character also implies, that all the females of this class are viviparous. In the human species, these glands are nearly symmetrical (the left is said to be very fre- quently larger than the right), and but two in number ; in most other animals they are more numerous, generally in the ratio of two for each of the young they ordinarily bring forth, and are mostly placed on the abdomen ; while in the human race they are situated on the chest, between the third and seventh ribs, so that the upper extremities can conveniently support the infant dining lactation. The niammse are also thoracic in the quadnunana and cheiroptera. The integmnent of the breast is soft and smooth ; in the young virgin of a pale white, or slightly bluish tint ; but in the aged, or in those who have borne children, it becomes uneven, wrinkled, thicker, and darker : a little below the centre is the nipple, an organ which presents great variety of appearances, cylindrical or conical, very long, or short, and even so depressed that the infant's lips can with difficulty embrace it ; it usually projects forwards and outwards, with a slight turn upwards ; in the virgin it is a rounded cone and nearly smooth, but in the lactating woman it presents a flattened, cribriform surface, its extremity being the broadest part ; in its centre are several depres- sions, or sometimes but one, in which are the small orifices of the milk ducts. It is surrounded by an areola, which in the young virgin is smooth, and of a pale red, or pinkish tint, but in the pregnant female, or in one who has suckled, it acquires a dark brownish hue. A num- ber of nervous papillae and small tubercles, sebaceous follicles, stud the skin both of the nipple and the areola, the secretion from winch de- fends it from excoriation dining lactation, the nipple being at that period very tender and irritable, and liable to cracks or fissures. The nipple consists of a reddish, cellular, and sensible tissue, traversed by the lactiferous ducts ; in the opinion of some, this is erectile tissue, but on dissection it does not present the spongy, cavernous tissue of the true erectile, but rather a vascular, fibrous sort of dartoid structure, which may account for the occasional erection of this organ, and the sudden expulsion of fluid from its ducts : the nipple is securely connected to the gland by a fascia surrounding the ducts, derived from that of the breast. The mammary gland, when separated from the surroimding adipose substance, appears of an hemispherical form, convex in front, slightly concave behind, and separated by a thin fascia from the pectoral muscle, on which it can be freely moved ; its circumference is thin and irregularly defined, some lobules being loose and scattered, and easily detached, particularly towards the axillary margin, hence it often presents an elliptical form in the transverse di- rection ; its convex surface is uneven, deep cells, or alveoli, filled with adeps. which previously smoothed off these irregularities: there is less of this adipose matter around the nipple than more externally. The 7H DUBLIN DISSECTOR. gland is surrounded by a capsule of cellular membrane, veiy variable in strength and distinctness ; it is prolonged into the gland, and sepa- rates and connects its lobules, vessels, and nerves : these processes (liga- menta suspensoria) are analogous to the septa in the testis ; anteriorly they are connected to the skin, and posteriorly to the fascia of the great pectoral ; thus they also serve to suspend and maintain the organ in its position ; in the old or emaciated, these become weak and elonga- ted, and the breast no longer occupies its original seat. This tissue in some is dense and fibrous, in others loose and cellular, on those diffe- rences depend, in a great degree, the firmness or softness of the organ ; the interstices between these septa are filled with adeps, on the greater or lesser qiiantity of which the size of the organ in a great degree de- pends ; owing to the same cause also the breasts in the male are occa- sionally found of considerable magnitude. The interior of the gland presents a white, fibrous appearance, divisible into masses, without that granular arrangement common to other conglomerate glands ; during lactation, however (the most suitable condition for the examination of the organ), the glandular grains are distinct, though very minute ; these granules are united into flattened lobules, and these again into lobes ; from each group of lobules a small excretory duct issues, evident by its white colour ; this, if injected, can be traced back into fine divisions, each of which ends, or rather commences in the fine coecal vesicle of which each granule is composed ; these ducts converge towards the areola, increasing in size but diminishing in number ; near the base of the nipple these terminate by five or six branches in small ampullae, or reservoirs ; in the human subject these scarcely deserve the name, but in most other mammalia they are of considerable size ; in the COAV, for example, they can con- tain a quart of fluid. From these ampullae the straight tubes proceed, twelve to twenty in number, and open on the cribriform surface of the nipple by very small orifices ; each duct is lined by an inflexion of the skin, which then assumes the mucous character, and is covered by a fine cellulo-fibrous tissue. Injection demonstrates, that the milk ducts have no valves, also that there is but little communication between them, or between the different lobes, as these latter can be injected with different coloured fluids ; hence, the breast may be regarded as an ag- gregate of glands, each capable of independent action, and each also liable to isolated disease. The mammary gland derives its arteries from the thoracic branches of the axillary, from the intercostals, and from the internal mammary, Avhich inosculates with the epigastric. The veins preponderate, and are arranged in two orders ; the deep set accompany and are closely connected to the arteries ; the superficial are subcutaneous and well developed, especially around the areola, where they present a plexiform anastomosis, thence they pass towards the circumference of the organ to join the deeper veins ; they can often be distinctly seen during life, and are veiy frequently much developed, and even varicose in certain DUBLIN DISSECTOR. 77 morbid conditions of the organ, also in elderly persons, or where the organ, once largo, has become atrophied. The nerves of the gland are derived from the intercostals, and from the brachial plexus, Avhile the integuments receive some filaments from the cervical nerves. The absorbents are very numerous ; they are superficial and deep ; the first proceed from the nipple and cutaneous glands ; the second from the glandular structure ; these pass into the axilla, enter the ab- sorbent glands, and then ascend, some internal, others external to the axillary vessels ; some open into the angle between the jugular and subclavian veins, others join the absorbents of the arm. From the sternal side of the nipple absorbent vessels also proceed, these pass through the intercostal spaces, into the mediastinum, and some absorbent glands situated there; some of these on the right side communicate with the absorbents of the liver ; all these vessels finally end in the angles between the jugular and subclavian veins. Some absorbents also pass from the posterior surface of the gland through the pectoral and intercostal muscles, accompany the intercostal ves- sels round to the posterior mediastinum, and either enter into the absor- bent glands in that region, or at once join the thoracic duct. In the breast these different sets of absorbents communicate together. The mammary glands in the male deserve examination, and require same brief description. The size is very variable, in some not larger than a pea, hi others they equal two inches. In those of effeminate appearance, or in whom the testes are atrophied, these glands have been found of the greatest size. The nipple and the areola present papillae and tubercles, as in the female, but smaller and less vascular. The gland consists of minute cells, and numerous small conical ducts, branching through it, these end in straight tubes which open on the nipple, and the whole is supported by a fascia. Cases are on record of the breasts in the male being found as large as in the female, and of the ducts emitting a serous fluid with the appearance of milk ; such cases explain the possibility of the male parent sustaining the infant, of which some well authenticated instances are recorded. The female breast is the seat of many morbid changes, viz., inflam- mation and suppuration, either in the body of the gland, or in the cellular tissue around it or behind it, that is, between it and the muscle ; enlargement ; atrophy ; tumours of various kinds, adipose, hydatid, cartilaginous, scirrhous, cancerous, &c. ; some indolent, chro- nic, and innocuous, others more rapid in their progress, fungoid, and malignant ; some involving the entire organ, others confined to cer- tain lobes, or certain portions of the interlobular cellular tissue.* PECTORALIS MAJOR, fiat and triangular, arises somewhat tendinous from the sternal half of the clavicle, from the anterior surface of the sternum, fleshy from the cartilages of the third, fourth, fifth, and sixth true ribs, and from an aponeurosis common to it and the external * See the invaluable treatise on this organ by Sir A. Cooper. 78 DUBLIN DISSECTOR. oblique muscle ; the clavicular fibres descend, the stemal pass hori- zontally, and the costal ascend obliquely ; all pass outwards in front of the axilla towards the humerus, into which they are inserted by a flat tendon into the anterior edge of the bicipital groove, and by an apo- neurosis into the fascia of the arm ; a line of cellular membrane sepa- rates the clavicular from the sternal portion ; in some cases these Fig. 19.* appear as distinct muscles. Use, the clavicular portion can raise the arm and draw it forward, the sternal can press it to the side, particu- larly if assisted by the latissimus dorsi, and the costal portion can draw it downwards and forwards : the whole muscle will draw the arm forwards and inwards on the chest ; if the arm have been rotated outwards, it can roll it inwards, and so pronate the hand ; if the arms * The muscles of the anterior aspect of the trunk ; on the right side the super- ficial layer is seen, and on the left side the deeper layer. 1. The frontal portion of the occipito-frontalis muscle. 2. The orhicularis palpebrarum. 3. The leva- tor labii superioris alseque nasi. 4. The levator labii superioris proprius. 5. The zygomaticus minor. 6. The zygomaticus major. 7. The levator anguli oris. 8. The masseter. 9. The platysma myoides. 10. A portion of the trapezius. 11. The sterno-hyoid and thyroid muscles. 12. The upper portion of the omo- hyoid muscle. 13. The sterno cleido-mastoideus. 14. The pectoralis major. 15. The deltoid. 16. The biceps. 17. The coraco-brachialis. 18. The triceps. 19. The serratus magnus. 20. A portion of the latissimus dorsi. '21. A part of the obliquus externus abdominis. 22. The pectoralis minor. 23. The subcla- vius muscle. 24. One of the internal intercostal muscles. 25. One of the ex- ternal intercostals. 26. The rectus abdominis ; on the left side the sheath of the muscle has been removed. DUBLIN DISSECTOR. 79 be fixed, and this pair of muscles act, they will draw the ribs upwards aud outwards, and thus, l>y enlarging the thorax, assist in inspiration. This muscle is covered by the skin, platysma, and mammary gland, and its insertion is partly concealed by the deltoid, it covers a portion of the sternum and of the true ribs, also the subclavian and lesser pec- toral muscles, the coraco-clavicular ligament, the thoracic and axillary U and nerves. Between the clavicular portion of this muscle, and the anterior edge of the deltoid, is a space tilled by cellular tissue, the cephalic vein, and a small artery. The tendinous fibres of the ster- nal portions of opposite sides decussate each other, and cover the ster- num with a sort of aponeurosis ; the insertion has a twisted appear- ance in front of the axilla, the sternal and costal portions being folded behind the clavicular, and inserted superior and posterior to it into the interior edge of the bicipital groove, wliile the clavicular is united to the deltoid, and is inserted into the humerus along with that muscle ; in some subjects a bursa may be found between these two insertions of the pectoral muscle. From the low r er edge of the costal portion a fleshy slip sometimes descends and joins either the rectus or external oblique muscle of the abdomen ; and in some a strong mus- cular band connects it to the inferior margin of the latissimus dorsi ; a tendinous band also has been observed to ascend from the upper edge of its insertion to the capsule of the joint. Make a perpendicular division of this muscle, reflect the edges, one towards the sternum, the other towards the shoulder ; and the lesser pectoral and subcla- vian muscles come into view. PECTORALIS MINOR, flat and triangular, arises from the external surface and upper edge of the third, fourth, and fifth ribs, sometimes from the second, external to their cartilages ; the fibres ascend obliquely outwards and backwards, and converging, end in a flat tendon, which is inserted into the inner and upper surface of the coracoid process, near its anterior extremity, being here connected with the coraco- brachialis and short-head of the biceps ; a band of this tendon fre- quently passes over this process through the triangular ligament, and is connected to it, or to the tendon of the supra-spinatus, or to the cap- sular ligament of the shoulder. Use, to draw the shoulder forwards, downwards, and inwards, also to assist the great pectoral in elevating the ribs in inspiration. This muscle is covered by the great pectoral, by the superior thoracic vessels and nerves, and partly at its insertion by the margin of the deltoid muscle, a few of its inferior fibres are covered only by the skin ; it lies anterior to the serratus magnus, axil- lary vessels, and nerves. As this muscle does not ascend so high as the clavicle, it forms the inferior boundary of a small subclavicular triangular region, which is bounded above by the subclavian muscle and costo- coracoid aponeurosis, or ligament ; internally by the ribs, and externally by the coracoid process : this space is traversed by the axil- lary vessels and brachial plexus of nerves ; it is closed, or covered by the clavicular portion of the great pectoral ; the cellular fissure between which and the deltoid leads into it ; by expanding this, or by dividing 80 DUBLIN DISSECTOR. a portion of the great pectoral, this space can be opened sufficiently to expose the axillary artery for the purpose of tying it. SUBCLAVIUS, small and round, arises by a flat tendon from the cartilage of the first rib, external to the rhomboid, or costo-clavicular ligament, soon becomes fleshy, and ascending outwards and backwards, is inserted into the external half of the inferior surface of the clavicle, extending as far outwards as the space between the conoid and tra- pezoid ligaments. Use, to draw the clavicle and shoulder forwards and downwards, also to elevate the first rib in inspiration, if the shoulder and clavicle be raised and fixed. This muscle is covered by the clavicle and great pectoral ; it lies anterior to the axillary vessels and nerves, which separate it from the first rib ; it is enclosed inferiorly in a thin but strong aponeurosis, which is attached to the cartilage of the rib, to the clavicle and subclavian muscle, from which it passes downwards and outwards to the coracoid process, arching across the great vessels, is then connected to that process, and to the tendon of the lesser pectoral ; this fascia is called by some the coraco-clamcular ligament, by others, the costo-coracoid ; it is sometimes very strong, and from the manner in which it is tensely extended over the vessels, and continued along them, especially the vein, it renders it difficult to feel the pulsation of the axillary artery below the clavicle, as also to separate it from the vein and nerves between which it lies. SEKRATUS MAGNUS, thin and broad, particularly anteriorly, placed behind the pectoral muscles and the axillary vessels, and between the scapula and the ribs, arises by eight or nine fleshy slips, from the eight or nine superior ribs ; the fibres ascend obliquely backwards, and are inserted between the subscapular, the rhomboid, and levator anguli muscles into the base of the scapula, but particularly into the superior and inferior angles. Use, to depress the scapula and draw it forwards, particularly the inferior angle, and thus by rotating this bone on its axis, to raise the acromion process and the shoulder joint ; when the upper extremity is fixed, this muscle can raise and draw outwards the ribs, so as to assist very considerably in inspiration. The serratus magnus lies on the ribs and intercostal muscles ; also on a portion of the serratus posticus ; external to it are the axillary vessels, the sca- pula and subscapular muscle ; the trapezius, latissimus dorsi, and rhom- boid muscles lie behind it, and the pectoral muscles are anterior to it ; an abundance of loose cellular membrane connected to its surfaces allows it to glide on the ribs, and also facilitates the movements of the scapula upon it. The four superior digitations lie behind those of the lesser pectoral, and the four inferior, which are only covered by the skin, indigitate with the origins of the external oblique. If the clavicle be separated from the sternum, and the scapula pulled from the side, this muscle will then become tense, and in this state it appears to con- sist of three portions, which differ in structure and in form : the supe- rior is a thick, short, and strong fasciculus, somewhat square, passing from the two first ribs beneath the axillary vessels and brachial plexus, to the superior angle of the scapxila ; its flat surface is directed up- 1M lll.IN niSSKCTOK. SI wards, and lies on a plane anterior to the next or middle division, which is very thin, consisting of hut. few lleshy fibres, connected toge- ther by an aponeumsis. Tins portion is of a triangular form, the apex FHJ. 20.* attached to the third and fourth ribs, the base to the basis of the scapula, ii( it always to the bone, but sometimes to a strong tendinous cord, or arch, which extends along tin's line from the superior to the inferior * A lateral view of the thorax and neck. 1. A portion of the occipital bone. "2. The mastoid process of the temporal bone. o. The anterior surface of the bo- dies df the cervical vertebrae. 4. The deep layer of muscles of the posterior cervical region. 5. The levator anguli scapula?. 6. The anterior scalenus mus- cle. 7. The middle and posterior scaleni. 8. The internal portion of the clavicle which has been sawn across. 9. Its external portion. 10. The sternum. 11. 1-'. lo. 14. 15. KJ. 17. 18. 19. The costal attachments of the serratus magnus. 20. -jo. 20. The external intercostal muscles. 21.21.21. Portion of the inter- nal intercostals. 22. The subscapular muscle. 2-3. The head of the humerus. 24. The coracoid process of the scapula. 25. The inferior angle of the scapula. G 82 DUBLIN DISSECTOK. angle and which is also common to the insertion of the greater rhom- boid ; in some two such tendinous arches exist, and in others none. The third, or inferior division of the serratus is the strongest and most extensive ; it is radiated or triangular ; the apex thick and fleshy, attached to the inferior angle of the scapula ; the base expanded in thin and long fasciculi on the ribs : to this portion the external res- piratory nerve is chiefly distributed. The serratus may be again exa- mined when dissecting the muscles on the back of the trunk. IXTERCOSTALES are twenty-two in number on each side, eleven external and eleven internal ; the external commence at the transverse processes of the dorsal vertebrae, arise from the inferior edge of each rib, descend in fasciculi obliquely forwards, and are inserted into the ex- ternal lip of the superior edge of the rib beneath, and terminate a little behind the costal extremity of the cartilages ; an aponeurosis, the fibres of which run in the same direction, supply their place as far as the sternum. The internal intercostal muscles take an opposite direc- tion, and decussate the former ; they commence at the sternum, and are discontinued at the angles of the ribs ; they arise from the inner lip of the lower edge of each cartilage and rib ; the fibres, paler and shorter than those of the external, descend obliquely backwards, and are inserted into the inner lip of the superior edge of the cartilage and rib beneath. Use, both laminae cooperate to raise the ribs, the first rib being fixed by the scaleni. The intercostal muscles, in elevating the ribs, also evert their lower edges, and twist them at their vertebral and sternal ends, and thus assist in inspiration by enlarging the chest transversely, and from before backwards. The internal layer lies on the pleura, and is separated from the external by the intercostal vessels and nerves ; the external layer is connected to the pleura only in the space between the angles of the ribs and the vertebra-. At the pos- terior extremity of the external intercostal muscles, there are the fol- lowing twelve small muscles, which, however, may be seen more fullv when the muscles of the back have been dissected. LEVATORES OosTABUM arise narrow and tendinous from the ex- tremity of each dorsal transverse process, descend obliquely outwards, and are inserted broad into the upper edge of the rib beneath, between its tubercle and angle ; their name denotes their use. They are pa- rallel to, and frequently appear as a portion of the external intercos- tals ; the first levator is short, and arises from the last cervical ver- tebra ; the inferior increase in length and size. These muscles are arranged by some, and not improperly, among those of the back. Be hind the sternum are a pair of small muscles, which cannot be seen until this bone is removed; we describe them now, although their dissection may be postponed until the thorax has been opened. TRIANGULARIS STERNI, or sterno-costalis, arises from the posterior surface and edge of the lower part of the sternum, and from the xiphoid cartilage ; the fibres ascend obliquely outwards, the inferior pass transversely, inserted into the cartilages of the fourth, fifth, and sixth ribs. Use, to depress and draw backwards the cartilages of the m r.Lix i>i--i:< nut. s:"! ril)s. s<. MS to assist in expiration. These muscles lie on the pleura, pericardium, and diaphragm, arc covered by the sternum, cartilages ot' the ribs, and mammary vessels. Tliey antagonize the external inter- costals, to whose fibres, however, they are parallel, but they arise from the more lixed, and are inserted into the more moveable part of the cartilage, and this fact also explains the cause of the external in- teivostals terminating at the ends of the rilis. and not continuing ;i- far forwards as the sternum. The mechanism of respiration shall be further considered when the diaphragm has been examined (see dissec- tion of it). In connexion with the muscles of the thorax, the student should study the anatomy of the axilla. SECTION II. IM^-KI TION 01 THK AXILLA. THK Axilla is a conical, or rather a triangular, pyramidal-shaped cavity, the apex superiorly at the coracoid process and clavicle, the base below, between the pectoralis major, and the latissimus dorsi muscles, and formed by the skin and a thick fascia ; it is bounded an- teriorly by the great and lesser pectoral muscles, internally by the serratus magnus and the ribs, externally by the scapula, subscapular muscle, and the upper part of the humerus, and posteriorly by the serratus. latissimus dorsi, and teres major muscles. The internal and posterior walls unite in an acute angle along the base of the scapula ; this angle is completely closed by the serratus muscle ; the anterior and internal, or thoracic boundaries also unite in a very acute angle, which is prolonged upon the thorax, beneath the pectoral muscles : the external angle is truncated, and presents a somewhat round sur- face, formed by the coraco-brachialis muscle, the humerus, and the shoulder joint ; the axillary artery can be compressed against the lower part of this surface. The axilla contains several lymphatic glands, vessels, and nerves, and a quantity of loose cellular and adipose tissue, which is continued from the neck beneath the clavicle, and which often presents a watery reddish appearance. When the pectoral muscles have been divided, and some cellular membrane removed, the axillary vein first appears; at the upper part of the axilla, this ves- sel is yen large, and is internal and anterior to the artery, connected to it by compact cellular tissue: it here rests upon the first intercostal muscle, the second rib, and the upper part of the serratus magnus; the eoraco-clavicular aponenrosis adheres to, and is continued on its anterior surface, it is also crossed by the thoracic arteries and nerves; through the rest of the axilla it approximates the artery, and descends more directly in front of it, though inclined to its inner side, and se- parated from it by the anterior branches of the brachial plexus of 84 DUBLIN DISSECTOR. nerves ; it receives the basilic vein below, the cephalic above, and the subscapular, circumflex, and thoracic branches intermediate. The axillary artery may be next seen, taking an oblique course downwards and outwards through tin's space, larger above, and close to the thorax, smaller below, and nearer to the arm ; thoracic and acromial branches are derived from it in front, the circumflex and subscapular behind ; all these branches, and even the trunk itself, are liable to varieties in size, number, position, and distribution. (See Vascular System}. At the upper part of the axilla, the brachial plexus of nerves is seen behind, and to the outer side of the artery, its cords collected into a bundle ; postei'ior to the lesser pectoral muscle it is somewhat unravelled, and its branches are entangled around the artery ; it then divides into axillary and brachial nerves, the former are the anterior and posterior thoracic and subscapular, the latter are the internal, cutaneous, median, ulnar, external or musculo-cutaneous, musculo-spiral, and articular or circumflex. Two or three filaments from the superior intercostal nerves traverse this region transversely, in front of the serratus, and are entangled with the thoracic vessels and nerves. Descending on the forepart of the serratus magnus, be- hind the great vessels and nerves, is the external respiratory nerve, a branch derived from the first roots of the plexus in the supra clavicu- lar region. At the lower part of the axilla, the artery may he ob- served in general to lie between the two roots of the median nerve, with the external cutaneous to its outer or humeral side, and with the ulnar and internal cutaneous to its inner or thoracic side, while pos- terior to it are the musculo-spiral and articular nerves. The general distribution of these branches will be noticed in the dissection of the upper extremity, and for their particular description see Anatomy of the Nervous System. The lymphatic vessels in this region are numerous and distinct, the principal set ascend from the arm; these are joined by several from the exterior of the thorax, from the mammary region, and from the inferior posterior part of the neck. The lymphatic glands are con- nected to the axillary vessels by the small branches which supply them ; one series of these lies posterior to the edge of the pectoral muscle ; from this a chain continues up to the coracoid process, and beneatli the clavicle to the glands in the neck ; another series lies on the subscapular muscle, and several are scattered indifferently through the axilla. In cases of malignant affections of the breast, some of these glands are often found diseased and require to be removed by the surgeon, at the time of extirpating the former. These glands also, to- gether with the surrounding cellular membrane, are very subject to acute inflammation and suppuration, large collections of pus are the result, which, if not opened sufficiently early, may prove troublesome, and even dangerous ; by pressure on the nerves and lymphatics, oedema and debility of the arm are induced, or the fluid may burrow between or beneath the muscles, and, by compressing the chest, dis- tress the respiration, or it may even open through one of the inter- costal spaces into the cavity of the pleura. 1>1 HI. IN IH--.SKCTDI;. 85 SECTION III. TIIK CAVITY OF THE THOHAX. Tin-: thorax is situated at the upper and anterior part of tho, trunk ; it contains tin- limits, the organs of respiration ; the heart, the chief in the circulation of the blood, also several nerves and vessels Fly. ~1\. * The situation and relations of the lungs, the heart, and the great vessels in the thorax. 1. 1. The pericardium cut open and its anterior portion removed, in order to display the heart. 2. The superior vena cava. '4. The same vessel covered by the pericardium, descending to 4. The right auricle of the heart. 5. The right or puhnonic ventricle of the heart. 0. The pulmonary artery a ris- ing from the right ventricle. 7. The appendix of the left auricle. 8. The left or aortic ventricle of the heart. !). The ascending portion of the arch of the aorta. KI. The transverse portion. 11. The arteria innominata. 1:2. The left carotid. 13. The left subclavian. 14. 14. The thvroid body or gland. 15. The trachea. 15. !}. The lungs. 17. 17. The pleura. " Slj n I 15 LIN DISSECTOR. passing to and from the heart, and through the cavity. This region is bounded anteriorly by the sternum and costal cartilages, laterally by the ribs and intercostal muscles, posteriorly by the vertebra; and angles of the ribs, inferiorly by the diaphragm, superiorly by the several muscles and fasciae connected to the clavicle, first rib, and sternum, and by the different parts passing into and out of the cavity. The thorax, viewed externally, presents a very different form before and after the upper extremities have been detached from it ; in the former state it appears of great transverse width above, and nar- row below ; whereas in the latter condition, it is seen to be very con- tracted above, and expanded below. The thorax may be compared to a section of a cone, the posterior fourth being removed, the three an- terior parts retained and united to each other. The axis of the cavity is oblique from above, downwards, and fonvards ; the base of the thorax is also oblique from before, backwards, and downwards, and the apex on the contrary is oblique from behind, fonvards, and down- wards ; hence the perpendicular diameter of the thorax is much greater posteriorly than it is -behind the sternum. The apex of the thorax is somewhat truncated, and presents an oval opening, longer transversely than from before backwards ; this, the superior orifice of the thorax, is bounded anteriorly by the upper edge of the sternum and intercla- vicular ligament, posteriorly by the. last cervical and first dorsal ver- tebrae, and laterally by the first ribs ; the several important parts which pass through this opening shall be noticed afterwards. The inferior circumference of the thorax is five or six times more extensive than the superior ; it is bounded by the xiphoid, the last true and all the false costal cartilages, and by the last dorsal and first lumbar vertebra? ; its longer diameter is also transverse. Open the cavity by dividing the cartilages of the ribs on each side of the sternum, and raising the latter from below upwards ; if we look under the sternum as we thus slowly raise it, we perceive that space called anterior mediastinum to be gradually developed, from the right and left pleura? separating from each other as we tear the loose cellular membrane, which naturally connects these membranes and the pericardium to the posterior surface of the bone ; when the sternum is removed, this region is fully exposed ; it is described as being of a triangular form, the base, the sternum ; the sides, the pleurae, converging behind, so as nearly to touch each other ; the apex, the small portion of pericardium left uncovered by the pleurse ; naturally, however, all the parts within the thorax are so closely applied to the parietes, that no space or cavity of a defined form, like that assigned to the anterior mediastinum, can truly be said to exist.* The dissector, however, may cause this space to ap- * For the purpose of examining the morbid appearances after death, the can- ties of the thorax and abdomen sire Irene-rally opened at the same time; an inci- sion, carried from the top of the sternum to the symphisis pnhis, through the in- teguments, muscles, and peritoneum, will brinjr the latter cavity into view ; next let the skin and muscles covering the front of the thorax be' turned back, which will expose the cartila.ws connecting the ribs with the sternum ; imme- diately at their point of connexion with the bone, these are to be cut ; in doing this take care not to wound the viscera within. DU1J1.IN IMSSKCTOK. *< pear inoiv distinct by the following precaution; before you divide the cartilages, push your lingers from the abdomen behind the sternum, and break down the cellular connexions between it and the pleura', then cut the cartilages very near the sternum, and raise the latter ; without tliis precaution before dividing the cartilages, the pleurae, par- ticularly the right, will be in almost every instance laid open, and so the appearance of the anterior mediastinum injured. This region in general inclines a little to the left side below, in consequence of the left pleura being more attached to the pericardium, which lies rather to the left of the middle line, whereas the right pleura is connected to the sternum in a vertical line ; the anterior mediastinum is wider su- periorly and interiorly than in the centre, hence some compare it to the letter X, and describe it as consisting of two triangular spaces, their apices joined in the centre, the base of one towards the neck, and that of the other towards the diaphragm ; the superior portion is larger in the tVetus, contains the origins of the sterno-hyoid and thy- roid muscles, and the remains of the thymus gland; inferiorly there is much loose cellular membrane, which leads from the neck to the abdominal muscles, also lymphatic glands, and close to the sternum are the mammary vessels, and the triangularis sterni muscle of the left side. Next examine the organs on each side of the thorax; these are the lungs and their investing membranes the pleura ; in almost all r.-spects these organs are similar on the right and left side, and therefore either may be selected for examination ; for this purpose lay open one side, suppose the right, of the thorax, by sawing through the ribs about their centre, and removing their anterior portion ; the first rib maybe left uninjured; thus the cavity of the right pleura Avill be opened, its glistening surface seen, with the lung lying col- lapsed ; or having' divided, with the saw, six or seven ribs at their angles, and cut through their cartilages near the sternum, the inter- vening bones may be raised by a careful dissection from the pleura, without o i)ening the cavity of the latter. The pleura; are serous membranes, their internal surface is smooth, polished, and free ; their external surface is connected by fine cellular membrane to the parietes of the thorax, and to the tissue of the lungs, over which they are reflected. That portion of each which invests the lungs is called pleura pulmonalis, and that which is connected to the parietes pleura parietalis or costalis, the latter portion of the membrane is much more dense and strong than the former ; each pleura is a .shut sac, of a conical shape, and contains only the serous vapour it exhales ; for although the lung appears within the cavity, it is yet really external to it or behind it ; internally each pleura pre- In some old subjects, where the cartilages of the ribs are in some degree ossi- fied, a .saw imi>t be employed; all the cartilages, except those of the first rib, bcin.u: divided, the sternum may be raised like the lid of a box, and a very con- venient liin-'e is made by euttin'tr the articulation between the first and second pieces of the sternum on the inside, opposite the second rib; the figure of the thorax will thus be preserved, and a sufficient view be obtained of its contents. DUBLIN DISSECTOR. sents one continuous surface, which can be traced throughout its whole extent ; thus we can perceive that the right pleura passes from the Fig. 22.* * A transverse section of the thorax opposite the fifth dorsal vertebra, to shew the relation of the pleura to the Avails of the chest, to the lungs, and to the peri- cardium. 1. The body of the fifth dorsal vertebra. 2. 2. Sections of the ribs. 3. A section of the sternum. 4. A section of the right lung. 5. Of the left lung. 6. The anterior surface of the heart, covered by the serous layer of the pericar- dium. 7. The trunk of the pulmonary artery issuing from the right ventricle of the heart. 8. The left, and 9. The right branch of the pulmonary artery. 10. A section of the aorta immediately above the sigmoid valves. 11. A part of the left, and 12. Part of the right auricle. 13. The superior vena cava. 14. The left bronchus. 15. The right bronchus. 16. The oesophagus. 17. The thoracic aorta. 18. 18. The cavity of the pleura. 19. 19. The costal layer of the pleura. 20.20. The pleura passing from the posterior walls of the chest, over the sides of the vertebral column to the posterior surface of the root of the lungs, leaving between them the .interval, 21. 21. called the posterior mediastinum. 22. The pulmonary layer of the pleura, covering the outer surface of the lung, and sink- ing into its fissures. 23. 23. The same membrane covering the internal surface of the lung. 24. 24. The pleura-, passing from the internal surface of the lungs, over the anterior surface of their roots, to attach itself to the sides of the pericar- dium. 25. 25. The pleura leaving the pericardium to reach the posterior surface of the anterior wall of thorax, where it is continuous with 19. the costal layer. 26. The anterior mediastinum. DCHI.IN i>issi;< TOK. B9 hack of tlu' sternum to form the side- of the anterior mediastinum, and, arriving at the forepart of the pericardium is continued along the side uf that bag as far back as the root of the lung, whence it is reflected over the anterior surface of this organ, sinking into its fissures, and connecting all its lobules to each other; having thus invested the whole lung, it arrives at the posterior surface of its root, from which it is reflected to the buck part of the pericardium, where it approaches the opposite pleura, to which it is connected by cellular membrane; thence it passes to the sides of the vertebrae, thus forming the side of the pos- terior mediastinum (to be examined presently) ; the pleura then ex- pands along the side of the spine, ascending as high as the transverse process of the sixth or seventh cervical vertebra, and descending to the diaphragm, the convex surface of which it covers ; on this muscle also it is reflected from the lower edge of the root of the lung by a fold called ligament urn latum pulmonis, loose and triangular, the base to- wards the diaphragm, one side connected to the lung, and the opposite to the mediastinum ; from the vertebrae, the pleura continues to pass outwards, lining the ribs and intercostal muscles, as far forwards as the side of the sternum, where the sac was opened, and the description commenced. The pleurae are of a conical form, the apex of each is in the neck, covered by the anterior scalenus and subclavian artery ; the base adheres to the diaphragm ; the right pleura is shorter but broader than the left, which is long and narrow ; the liver on the right side and the heart on the left cause these differences to exist ; the apex of the right is often higher hi the neck than that of the left. The pleura is covered by a strong fascia, which can be detached more easily from the costal than from the other divisions of this membrane, except the confines of the mediastina ; the phrenic portion is more adherent than the costal, but less so than the pulmonic ; on the pericardiac, and some- times on the phrenic portions, small, fatty appendices exist, analogous to those on the colon intestine. All portions of the pleurae are covered by a fascia, which in some situations is so fine, delicate, and trans- parent, as to be difficult of demonstration ; on the costal portion it is very strong, on the phrenic less so, on the mediastinal it is very dis- tinct, and even appears in some places continuous with the fibrous layer of the pericardium, though separated from it in others, as in the line of the phrenic nerves; beneath the pulmonic, in a perfectly healthy lung, it is extremely thin, though strong, resisting, and elastic, andean be exposed by very cautiously scratching ofF the serous layer from a small portion of lung distended and held tense ; the transpa- rent fascia can then also be dissected off the ah*- cells; therefore, strictly speaking, the pleura? are, like most other serous and synovial membranes, libro-serous, and consist of three layers or tissues; the external or the adherent layer is fibrous, the middle a fine, subserous, cellular tissue, and lastly, the serous lining. In the costal, phrenic, and mediastinal portions, these three components can at all times be made distinct, and equally so in the pulmonic portion on a lung which has been long affected with chronic inflammation. This fibrous struc- ^^ ry Y 90 DUBLIN DISSECTOK. ture of the pleura serves to explain the pain of plenrodyne and pleu- ritis, also, as Cruveilhier remarks,* why external abscesses so sel- dom perforate into the cavity of the chest, and why pleuritic efl'u- sions are so long retained before they point externally ; also, as Stokes j" has observed, the rarity of perforations of the pleura pulmonalis in ulcerations of the lung, which have approached so near the surface as to be bounded only by this libro-serous investment. The uses of the pleura are to serve as a fine, yielding, elastic, and insulating- integu- ment to the lungs, to strengthen the diaphragm, and to complete the walls of the thorax, while the lubricating serous exhalation which constantly moistens the polished, and at all times contiguous surfaces of their visceral and parietal layers, facilitates those mechanical changes in the form of the lungs, and in the condition of the walls of the chest, which are requisite in the respiratory process. The two pleurae have been resembled to two bladders placed nearly parallel to each other, not having any communication, but touching each other along the mesial line ; this juxta-position of the two pleurae between the sternum and vertebrae forms a sort of partition between the right and left side of the thorax ; this partition is called mediastinum ; it consists of course of two lamina;, right and left, connected anteriorly to the sternum, posteriorly to the spine ; these lamina' are separated from each other in three situations, in order to enclose certain organs, so that the mediastinum is divided into, first, the anterior parr, or an- terior mediastinum, which has been already examined ; second, the middle part, or middle mediastinum, which contains the heart and pe- ricardium, with the phrenic nerves, the ascending aorta, and superior vena cava, the division of the trachea, and the pulmonary arteries and veins ; and third, the posterior mediastinum, which lies in front of the vertebra?, and which the student may next examine. The posterior mediastinum extends in a vertical direction from the third to the tenth dorsal vertebra, behind the pericardium and roots of the lungs, and in front of the spine ; to obtain a view of the parts con- tained in it, draw the right lung forward, and to the left side, and make a perpendicular division of the right pleura, between the root of the lung and the spine. This region is described as being of a trian- gular form, the base posteriorly, the pleura- forming its sides, and the pericardium its apex ; like the anterior mediastinum, however, it has naturally no exact figure, the pleura; being folded round the organs which lie between them. In the posterior mediastinum we find the oesophagus and eighth pair of nerves, the thoracic duct, vena a/.ygos, descending aorta, splanchnic nerves, several lymphatic glands, and a considerable quantity of fine, loose, cellular membrane; the division of the trachea is immediately in front of this space, just at its commence- ment. The oesophagus is anterior to the other parts in the posterior mediastinum; this tube having passed behind the left division of the trachea, enters this space, and descends obliquely forwards behind the * Anat. Descrip. t. 2. p. 800. f Diseases of the Chest, p. 4(!o. !M iM-ricardinm and before the aorta; above, it lies to the right side of tins vessel, but In-low it is to the left ; in the lower part of its course it is surrounded by branches of the eighth pair of nerves, and, enlarging a little, it perforates the lieshy part of the diaphragm, opposite the ninth or tenth dorsal vertebra, and joins the stomach. The eighth pair of nerves having passed behind the roots of the lungs, attach themselves to the u-sophagus, and form by their branches a plexns around it (the cesophaueal plexus} ; the left nerve then descends on the fore, and the right on the back part of this tube to the stomach. The thoracic aorta enters this region about the fourth or fifth dorsal vertebra, and descends along the spine, to its left side above, but nearly in the mesial line below; about the eleventh or twelfth dorsal vertebra it passes between the crura of the diaphragm into the abdo- men ; in this course the aorta furnishes the following branches : two or three bronchial arteries, which go to the lungs, as many oesophageal branches, and nine or ten pair of intercostal arteries, whose name im- plies their destination. The vena azygos commences in the abdomen by a small branch from one of the superior lumbar veins, enters the thorax behind the right side of the posterior mediastinum, covered by the right pleura ; and opposite the third or fourth dorsal vertebra it arches forwards over the root of the right lung, and opens into the superior vena cava, as that vessel is entering the pericardium. The vena azygos in this course receives the bronchial, cesophageal,and intercostal veins ; those of the left side often unite into one branch, which, passing behind the aorta, joins opposite the sixth or seventh vertebra, the principal trunk on the right side. The thoracic duct also commences in the abdomen, on the second or third vertebra behind the aorta, in a sums, called receptaculum chyli ; contracting in si/e it enters the posterior mediastinum, along with, and to the right side of the aorta; it ascends close to this vessel, between it and the vena a/ygos, imbedded in fat, and opposite to the fifth or sixth dorsal vertebra it attaches itself to the back of the oesophagus, runs ob- liquely along it, behind the arch of the aorta, to the left side, and as- cends in the neck behind the left carotid artery and jugular vein, as high as t lie sixth cervical vertebra ; it then bends downwards and outwards, and enters the left subclavian, just before it joins the jugular vein. The coats of the thoracic duct are so fine and thin, that frequently it is difficult to see or trace this vessel, unless previously injected or in- flated from the abdomen; it is often found divided into two or three branches which unite again. (For a more particular description of it, see. tin: Anatomy of the Absorbent System}. The splanchnic nerves (trim- by four or live filaments from the dorsal ganglions of the sym- pathetic nerve: the lirst is from the fifth or sixth ganglion, the rest arise in succession below it ; all unite and form the splanchnic nerves, which descend obliquely forwards on each side of the aorta, along with which they enter the abdomen, where each terminates in a large ganglion, termed xaniltuKir ; these two ganglions are joined together 92 DUBLIN DISSECTOR. by numerous branches, which constitute the cceliac or solar plexus, from which the greater number of the abdominal viscera are supplied with nerves. In the dissection of the posterior mediastinum, the sym- pathetic nerve is also seen on each side ; it does not lie in this space, but descends external to it, between the pleurae and the heads of the ribs ; opposite each intercostal space it forms a ganglion, from which some branches pass to join the dorsal spinal nerves, others to form the great splanchnic ; and at the lower part of the thorax, two or three filaments often unite to form a small nerve, called lesser splanchnic, which enters the abdomen, behind or through the crura of the dia- phragm, and joins the renal plexus of nerves. The sympathetic on each side enters the thorax close to the neck of the first rib, where it forms a large ganglion ; it passes from this cavity by a very small iilament, between the crus of the diaphragm and the psoas magnus, into the abdomen, where it again enlarges considerably. (See the Anatomy of the Nervous System.^) The division of the trachea, the last part of any importance connected with the posterior mediastinum, does not, strictly speaking, lie in this space, but, like the heart and great vessels, it is in the middle mediastinum, or between the anterior and posterior ; this tube can be more conveniently examined afterwards, when we are dissecting the parts which pass through the upper open- ing of the thorax. Next examine the lungs. The lungs are situated at either side of the spine, and, when dis- tended \vith air, as they constantly are during life, they so exactly fill each side of the thorax that the pleura pulinonalis and costalis are always in such perfect apposition, that there never can be any inter- mediate cavity ; they are of a conical figure, the apex round and often irregularly bulged, when distended rises into the neck to a height vary- ing from one to two inches above the level of the first rib, which bone occasionally indents it anteriorly ; the apex of the right usually rises higher than that of the left ; the base concave, particularly of the right, accurately moulded to the convexity of the diaphragm, presents an inclined plane from before backwards, hence the vertical diameter of the lungs is much longer behind than before ; the dia- phragm is so convex on the right side, that a sort of angular gutter exists between it and the ribs, particularly behind, into this the lung fits exactly, by a thin, prolonged margin ; this conformation is less evi- dent on the left side ; it depends on the position of the liver, the con- vexity of which raises the diaphragm into the corresponding concavitv in the base of the lung ; this close apposition of the liver, diaphragm, and lung, explains how a wound, penetrating the right side of the chest, so high even as the fourth intercostal space, may also open the abdominal cavity, and thus injure, at once, the two layers of the pleura?, the lung, and the diaphragm, also the two layers of perito- neum, and the liver ; it also accounts for sympathy in disease, and the difficulty in diagnosis, as also for the occasional discharge of hepatic abscess into the right pleura, or into the bronchial tubes of the right lung. The posterior edge of the lung is long, thick, round, and ver- 03 tical, it fills the concavities of the ribs at each side of the spine. The anterior edge is much shorter, is thin, irregular, and oblique, that of tin- left lung presents two notches, a small, narrow one above, correspond- ing to the left subelavian artery, and a large open one below, opposite the apex of the heart : the anterior edge of the right lung also pre- sents two notches, but smaller, the superior corresponds to the descend- ing cava, the inferior to the right auricle. The external surface of eaeh lung is convex, corresponds to the pleura costalis, and presents a deep fissure, which commences below and behind the apex, descends obliquely forwards, and ends in front of the base ; it divides each lung into tAvo lobes, one superior and anterior, the other larger, inferior, and posterior, the base of the latter is the base of the lung, that of the former is above at the apex of the organ. This interlobular fissure penetrates to a great depth, and its opposed surfaces are smooth and serous ; from the middle of that on the right side, a short fissure leads forwards to the anterior edge of the lung, and cuts oft' the middle lobe from the superior ; this does not penetrate so deeply as the great fis- sure, it is sometimes absent, and in some it exists on the left lung also ; occasionally there are four lobes in the right, and three or four in the left, and examples are recorded of even five or six, the ordinary conformation in many other animals. The internal surface of each lung looks towards the mediastina, and is attached to the heart by its root, anterior to which, this surface particularly on the left side, is concave for the reception of the pericardium and its contents. The root of each lung is situated a little above the centre of the in- ternal surface, and about two-thirds from the anterior edge ; the phrenic nerve and a few filaments of the pneumogastric nerve, which form the small anterior pulmonary plexus, lie anterior to it, and the great pulmonary plexus is posterior to it ; the fold called liga- mentum-latum is below it. The superior cava, and the right auricle of the heart are in front of the root of the right lung, and the vena axygos bends round its upper margin; the arch of the aorta is above that of the left side, and the descending aorta is behind it. Each root consists of several vessels and nerves connected together by cellular tis- sue, and all enclosed between the lamina} of the pleura ; dissect off this membrane from the forepart of the root, and we shall observe the two pulmonary veins inferior, but anterior to the pulmonary artery, which is immediately above and behind them ; posterior and superior to the artery is the bronchial tube ; a quantity of cellular tissue connects these- vessels, and contains the bronchial arteries and veins, lymphatic ve-sels, and glands, also several nerves, which are derived from the pulmonary plexus. In the root of the left lung the bronchial tube is rather inferior to the artery, but still posterior to it, as on the right side. The function of the several parts in the root of each lung is as follows : the two pulmonary arteries convey from the heart, through the lungs, the dark and venous blood; the four pulmonary veins re- turn to the heart, this blood changed into bright arterial; the two bronchial tubes distribute the air through the lungs ; the bronchial itl DUBLIN DISSECTOR. arteries small, three or four on each side arise from the aorta, these, together with lymphatic vessels, and the nervous filaments, from the pneumogastric and sympathetic, are distributed through all parts Fig. 23.* of these organs, on the parietes of the air tubes, and in the interlo- bular cellular tissue, for the purposes of nutrition ; the corresponding bronchial veins open into the vena azygos, or into some of the inter- costal veins. The lungs have a peculiar soft, emphysematous feel, and are so light as to float in water ; their colour is grey, interspersed with spots of dark blue or blackish tint ; the younger the subject the redder they will be found ; in the adult they are generally grey, and slightly streaked with dark lines enclosing polygonal spaces ; in the old they are usually mottled with blue or black spots, which exist, not merely on the surface, but through their substance. The lungs are composed of the ramifications of the pulmonary arteries and veins, of the bron- chial arteries and veins, of the pulmonary nerves, of lymphatic vessels and glands, and of the ramifications of the bronchial tubes, which end * Anterior view of the heart and. roots of the lungs ; the lungs are separated from each other, and drawn outwards. 1. The right lung. 2. The left lung. 3. The interior portion of the trachea. 4. The right bronchus. 5. The left bronchus. 6. The anterior surface of the heart. 7. The right auricle. 8. The appendix of the left auricle. 9. The superior vena cava. 10. The inferior vena cava. 1J. The aorta, cut across a little above its origin. 12. The trunk of the pulmo- nary artery. 13. The right pulmonary artery. 14. The left pulmonary artery. 15. The ductns arteriosus. Ifi. The superior edge of the left auricle. 17 and 18. The superior and inferior pulmonary veins of the right side. 19 and 20. Supe- rior and inferior pulmonary veins of the left side. nrm.ix DISSECTOR. .> in niunorous air cells, the latter, together with their connecting cellu- lar tissue, constitute the principal bulk of the lungs. These cells are eolleeteil at lirst in clusters, and joined by cellular membrane into lobules : these last are again united into larger masses by the pleura, Fig. 24.* so as to form lobes. The air- cells are the terminations of the bron- chial vessels ; they are of an irregular form, are lined by mucous mem- brane, and covered by a delicate, fibrous, or, as some suppose, a mus- cular lamina ; each bronchus divides into two branches, these again subdivide into two, and so on in binary order, thus increasing in number, but diminishing in size; their final capillary 1 (ranches end in small ca-cal sacs or air-cells ; if any one bronchial tube be inflated, i all cells and lobules become observable on the surface, marked out and bounded by depressed bands of interlobular cellular tissue, and * The lower part of the trachea, and the left bronchus laid open dieissei son). 1. The oriticc of the riirht bronchus. 2. Longitudinal and elastic fibres. 3. The mucous membrane, separated from the longitudinal fibres. 4. Transverse mus- cular fibres expired by the removal of the mucous membrane and longitudinal fibivs. ",. The pulmonary artery injected and cut across. 99 DUBLIN DISSECTOR. it is principally in those lines, and at their angular junctions, the dark streaks and spots already mentioned may be observed ; the larger bronchial tubes are composed of the same materials as the trachea, but in the smaller branches there is no cartilaginous structure. On the delicate parietes of the latter, the fine capillaries of the pulmonary arteries and veins are spread, and here during life is effect- ed that important change in the blood, from venous to arterial, which appears to be the great design of the function of respiration. As to the minute structure and exact arrangement of the air-cells, it is dif- ficult to speak with confidence, Reisseisen and others maintain that each cell is but the globular dilatation of the ultimate ramification of a bronchial tube, like the cells or coecal extremities of the excretory ducts in the secreting glands, and that each lobule is an aggregate or group of cells, connected together and attached to a bronchial tube and its ramifications, like a bunch of fruit attached each by its own pe- dicle to the stalk, and that these cells communicate, not directly, but through the common tube from which their ducts proceed, and through which the atmosphere enters their cavity. Although an inspection of the foetal lungs encourages this view, yet it is by no means confirmed in those of the adult ; here the cells appear far more numerous than the ramifications of the bronchial tubes can even be supposed to be, and, therefore, some anatomists believe that each fine tube does not end in a single cell, but that it leads to a cluster of cells which communicate with each other. My own observations on this minute structure, not merely in man, but in many other animals, lead me to concur in this opinion. Addison (Phil. Trans, note, 1842), conceives that Reis- seisen's account is correct as regards these organs in the foetus, that is, that the tubes there end, each in a cell or coacal sac without adja- cent communications, but that after respiration a change occurs ; the feeble membrane composing these cells, becomes distended laterally into rounded inflations, new cells become moulded by angular pressure, and communicate freely with each other, the septa being incomplete, being mere filaments or laminae ; this open, reticulated texture in a single lobule, is analogous to the arrangement through the whole organ in some of the class reptilia. Thus we may regard each lobule as a small, but perfect lung, pos- sessing its air tubes and its bloodvessels, and capable of performing its functions, and often even exhibiting isolated disease, independent of the adjacent lobules; the interlobular cellular tissue is fine andreticii- lar, never contains adeps, but is permeable to serous and emphvso- matous effusions ; these lobules are of variable size and shape, those towards the surface are the largest, and are pyramidal or wedge- shaped, those deeper seated are of irregular figures, but accurately adapted to each other ; the cells in each lobule are generally said to be globular, but they have no determined form, some are larger and more permeable to the air than others; they are small in the foetal lung, and larger in the old than in the adult, and larger above than below ; in chronic cough they are often dilated, and Avhen very much so, they constitute the disease called pulmonary or vesicular emphy- sema, an affection very different from the cellular or interlolmlar em- physema : the air cells and smaller air-vessels are very thin, and SB a very delicate texture, although they exhibit much power of resistance in the injection or inflation of any part of the lung ; they are composed of mucous membrane, covered by a cellular and fibrous tissue, but there is no evidence of any muscular structure, the blood- Is lie between the contiguous walls of two of these air tubes and air cells, so that the capillary streams are exposed on all sides to the influence of the air. The spongy and yielding tissue of the lungs admits of the free en- trance and rapid circulation of the air through their cells, all which become distended in the moment of inspiration ; in this act the lungs are wholly passive, the air distending them in the exact proportion with which the parietes of the chest are expanded ; in expiration, the contraction of the thorax expels a great portion of the air from the cells, and thus the lungs become diminished in capacity ; in effecting this change, the elasticity of these organs, aided by the muscular energy of the bronchial tubes, may assist the muscular and elastic 1 tower of the parietes of the chest. In expiration the air-cells are not wholly emptied, as no power can completely discharge the air from lungs that have once breathed See Anatomy of the Diaphragm and Trachea. The pleurae and lungs are the seat of many morbid changes ; the pleura, when inflamed, becomes thickened and vascular, and presents a deposit of lymph on the surface, which commonly causes an adhesion between the pleura costalis and pulmonalis to a very variable extent ; when these adhesions are recent, they are soft and easily broken, but when of long standing they become strong and resisting ; adhesions of different extent and length are very common appearances. Portions of the pleura costalis are found sometimes converted into bony plates. Such deposits, when extensive, resemble the natural condition of the ribs in the turtle and the tortoise ; this deposit takes place in the fibrous, 7iot in the serous tissue ; it occasionally occurs also in the pleura pulmonalis, which corroborates the statement of the fascia ex- isting there also, and apparently without having caused any inflam- mation or inconvenience. The cavity of each pleura is also the seat of effusion ; if of water or serum, it is named hydro-thorax, if of air, pneumo-thorax, if of pus, empyema ; the operation of paracentesis, or tapping, is frequently required in the latter case. The place usually d for this operation is ahou* midway in the fifth or sixth in- t< Tcostal space, just in front of the digitations of the serratus magnus. The lungs are often found in a state of inflammation (pneumonia), this is denoted by increased density, weight, and colour, sometimes dark, sometimes very florid : the affected portion is often so heavy as tu sink in water: the dark colour, from the gravitation of blood to a depending part, must not be confounded Avith that arising from disease. Inflammation sometimes ends in gangrene, and sometinu -s in abfl H 98 DUBLIN DISSECTOK. which may open into the trachea or into the pleura, and so cause em- pyema. The lungs are very subject to tubercles, which present great variety in size, from a pin's head to that of a walnut ; when small they are firm, when large they become soft, suppurate in the centre, and form abscesses or vomica?, which often communicate with the bronchial tubes. Tubercles are often found in the upper part of the right lung, when the remainder of both organs is healthy. The lungs are also occasionally the seat of cancerous and fungoid tubercle and tumour. We shall next direct our attention to the parts passing through the upper orifice of the thorax. Posterior to the deep cervical fascia, we perceive the sterno-hyoid and thyroid muscles first ascending through this opening ; behind these is a quantity of cellular membrane, and the remains of the thy- mus gland ; next are the right and left venae innominatce, the former descending perpendicularly, the latter obliquely across this opening : these two veins unite opposite the first intercostal space or the carti lage of the second rib of the right side, and form the superior vena cava, which soon enters the pericardium, and empties itself into the right auricle. The venae innominatse are formed by the confluence of the internal jugular and subclavian, opposite the sternal end of each clavicle ; the right is about an inch and a-half long, descends almost vertically, inclining a little inwards towards the mesial line, parallel, but superficial and external to the arteria innominata ; at its com- mencement it is joined by the right absorbent trunk, afterwards by the vertebral, and in general also by the internal mammary and in- ferior thyroid veins of the right side. The left is much longer and a little larger, runs across this opening almost transversely, but descend- ing a little towards the right side, is convex forwards, is covered by the stemo-clavicular joint, the upper border of the sternum, the ster- nal muscles, and a strong layer of cervical fascia, a lamina of which connects it to the thoracic septum and to the pericardium ; it crosses over the three large arteries and the trachea, and receives at its origin the thoracic duct, and in its course the vertebral, mammary, and inferior thyroid veins of the left side, also the superior intercostal, the phrenic, thymic, mediastinic, and sometimes also the right mam- mary and thyroid. The superior cava is smaller than the united innominata?, about three inches in length ; descends along the right side of the mediastinum, inclining mesially, so as to be convex towards the right side, is separated from the right lung by the right pleura and the phrenic nerve, which from being external becomes rather anterior to it ; the aorta is anterior and to its right side, and the remains of the thymus and cellular tissue are hi front of it ; opposite the upper edge of the third costal cartilage it enters the pericardium, the serous layer of which is reflected down upon it and covers its two anterior thirds, or fourths ; posteriorly this portion of the cava is in contact with the pulmonary artery and superior pulmonary vein in the root of the right lung ; opposite the point of serous reflection, the vena azygos enters it posteriorly, occasionally, also, small branches from the adjacent parts join it in its descent ; its course and relations in the pericardium shall r>rnux DISSECTOR. 99 le considered presently in the description of the heart Behind the YI-N;V innominata-, (he phrenic and eighth pair of nerves cuter the chest ; the former is external and anterior to the latter, and both arc anterior to the subclavian arterio. The phrenic nerves, accompanied for a short distance by the internal mammary vessels in front of which they crov*. descend through the thorax, anterior to the roots of the I un.us, to the diaphragm, to which they are distributed ; the right de- scends vertically along the right vena innominata,, cava and pericardium, in front of the root of the lung, and to the right of the inferior cava to the diaphragm ; the left, as it descends to the chest, lies external to the left carotid artery, and in front of the par vagum, crosses the side of the arch of the aorta, to the median line of that nerve, and reaches the pericardium, on which it takes a curved course, convex to the left, around and behind the apex of the heart, it is therefore longer, and on a plane somewhat posterior to the right ; a small artery, from the internal mammary, accompanies each of these nerves, The eighth pair, entering the chest between the subclavian vein and artery, pass backwards behind the roots of the lungs, on Avhich they form an extensive plexus, pulmonary plexus ; they then enter the posterior mediastinum, and become attached to the oesophagus, which conducts them to the stomach. We next perceive the innominata, left carotid, and left subclavian arteries, ascending out of this cavity ; the innominata is most anterior, and the left subclavian the most pos- terior of the three ; the cardiac nerves are connected to these arteries. The trachea enters the thorax, behind these vessels, and inclines a little to the right side ; this tube commences opposite the fifth cervical vertebra, descends at first in the middle line, but as it enters the chest it inclines to the right, the aorta pressing on its left side, a little lower down ; in the thorax it descends obliquely backwards, and opposite the third dorsal vertebra divides into the right and left bronchial tubes ; a number of dark lymphatic glands (the broncJdal glands), of very irregular form, lie in the angle of the division, and adhere closely to the branches. Its average length is about five inches ; but as it admits of elongation, and possesses considerable elasticity ; it varies in this respect according as the neck is extended or flexed ; the loose cellular tissue around it permits free motion longitudinally, and even laterally, which latter circumstance, in the operation of tracheo- tomy during life, has proved a source of difficulty and danger ; its dia- meter varies according to age, sex, and general development of the respiratory organs ; it is larger hi man than in woman ; the transverse exceeds a little the antero-posterior diameter, as it deviates from a cylinder, the posterior third being flattened ; in tin's respect it differs from the cricoid cartilage, wliich is nearly circular, and which in other respects it equals, though in many instances I have known the trachea to exceed it in capacity ; in the adult male the transverse axis is be- tween half and three-quarters of an inch ; it is sometimes a little con- tracted at first, or about the third or fourth ring, and it is frequently enlarged just above the bifurcation ; in some it gradually enlarges as H2 100 DUBLLN DISS1XTOII. it descends, so as to assume a conical form, the base below ; it is very variable in this respect ; some have remarked both general and par- tial dilatation, in persons afflicted with severe cough ; such alterations in diameter are remarkable and normal in many of the bird tribe. The cervical and thoracic portions of the trachea are nearly of equal length ; the relations of the former are as follow : the first ring is superficial ; the second, third, and often the fourth are covered by the middle lobe of the thyroid body, which adheres closely ; below this, the cervical fasciae and the sterno-hyoid and thyroid muscles cover it, especially the latter, which being connected together by a sort of raphe derived from the deep fascia prevents its being even distinctly felt ; behind these muscles is a considerable quantity of cellulo-adipose membrane, containing the venous plexus of the inferior thyroid veins, in their descent to the left vena innominata ; a small artery (middle thyroid) frequently traverses this plexus ; near the root of the neck the arteria innominata passes in front of it and to its right side, rising to a variable height ; the left vena innominata also crosses it nearly on a level with the upper border of the sternum. On either side of the trachea in the neck we find the lateral lobes of the thyroid body, tin- sheath of the carotid arteiy, lymphatic glands, and much cellular and adipose tissue ; its flat posterior surface rests on the oesophagus, but towards the bottom of the neck the latter projects to the left side, and supports the left recurrent nerve; the right recurrent is behind the trachea. The proximity of the oesophagus to the fiat and membra- nous surface of the trachea accounts for the danger of suffocation from any large substance becoming impacted in the former, and the necessity for performing tracheotomy if it cannot be dislodged. This posterior flattening of the trachea has been thought by some to have been de- signed to facilitate deglutition, by admitting the distention of the oasophagus ; however, the same structure is continued in the bronchi, where no such intention could apply ; and in some animals the carti- lages are perfectly annular, and in others they even project behind in an angular form. In the thorax, the trachea is between the lungs and pleura, just above and in front of the posterior mediastinum ; ante- rior to it are the sternum with its muscles, the remains of the thy m us body, much cellular tissue, and the arteria innominata ; the left carotid is also in front and to its left side, a little lower down the arch of the aorta rests upon its anterior and left aspect ; the division of the pulmo- nary artery is immediately in front of the left bronchus ; these relations to the great vessels are of great interest and importance, in account- ing for many of the symptoms, as w r ell as the fatal results of aneurism of the aorta, or of any of the large arteries in this situation ; poste- riorly the trachea still rests on the oesophagus, on either side are the pleura and the pneumogastric nerves, and at its very entrance into the chest the recurrents also ; much cellular tissue and many lymphatic glands surround it, continuous with similar structures in the neck. The trachea, which serves as the free passage for the air to and from the lungs, and therefore requires to be permanently open, is composed THT.I.TN mssKCTOR. 101 of different tissues, vix. : lil>rous, cartilaginous, clastic, mucous nicm- hranc, with glands and muscular tiluvs. The fibrous membrane is tlie <'sst'iitial basis, it forms the continued tube, is attached above to the cricoid cartilage, divides below into the two bronchi, and is continued along their ramifications ihroogh the lungs as far, probably, as their terminations in the air cells : in this tissue the annular cartilaginous plates are deposited verv close to its inner or mucous surface ; the average number of these is eighteen, each forms about three-fourths of a circle, the posterior deficiency being supplied by, the fibrous mem- brane and transverse muscular fibres; each cartilage^ ccirfoer' ante - riorly and externally, and covered by the fibrou,'ile:byane,"e 1 brvcave posteriorly, and lined by mucous membrane their upper^aiyl Ipwjpj; margins are thin, attached to and enclosed in thp /jhrous >tfli>e/ t6ejr' extremities are blunt points ; as to size they J are J veiyiivegi Jar,' often" larger in one part than in another, they are not, therefore, always parallel : two are sometimes partially united, occasionally one or more will be found bifurcated ; the first ring is deeper than the others, par- ticularly in front, and is sometimes continuous with the cricoid ; the two last rings are also larger than those that preceded them ; the last >itsp>"ent, mid perforated by many small foramina, orifices of the mucous j/Lii >\b. \vhich are numerous in the parietes of this tube. These glands are found in three situations ; first, on the posterior flat Vm>\ac;eofthe tracliai and' connected to the fibrous membrane, are seve- ' ralof l a flattened, ovoid shape, these are the largest ; secondly, between this membrane and the muscular fibres, also in the interstices of the latter, we find almost a regular layer of these bodies ; and lastly, be- tween the edges of the cartilages beneath the fibrous coat, also between the former and the mucous lining a number of veiy small ones may be detected ; these glands, no doubt, furnish that fine muco-serous secre- tion which constantly coats the surface of the membrane and defends it from the irritation of the air. The arteries of the trachea are derived chiefly from the superior and inferior thyroid ; the veins are superficial and deep, the latter are subjacent to the mucous membrane posteriorly and laterally, and receive branches regularly from each annular interstice, they open into the adjacent veins ; the nerves are derived from the pneumo-gastrie and recurrents. The two bronchial tubes separate at an obtuse, or nearly a right angle ; a strong, elastic, triangular ligament occupies the angle of bifurcation, and limits their separation ; their united area; exceed that of the trachea. The right tube is the larger, as the right lung exceeds the left, it takes a short and nearly transverse course into the root of the right lung, above and behind the right pulmonary artery, having the vena azygos curved round it from behind upwards and forwards ; it soon divides into three branches. The left bronchus is smaller but much longer, and passes obliquely downwards into the root of the left lung, behind and below the level of the left pulmonary artery, and divides into two branches ; in this course it passes through the arch of the aorta, embraced by it above, and in front of the oeso- phagus, thoracic duct, and descending aorta. Both bronchi are inti- mately connected to the great pulmonic plexus of nerves, and to several lymphatic glands, wliich are usually, in the adult, of a very dark colour and soft consistence, and are frequently, in a diseased or altered state, indurated into a mass, or converted into a cheesy or cal- careous substance ; the pneumo-gastric and the left recurrent nerves will be often found imbedded in or surrounded by these morbid structures. The pulmonary arteries in the root of each lung, at first anterior to, gradually rise above the bronchial tubes and then pass be- hind them ; the veins at first are between the tubes and arteries, bxit K. 103 as they approach the heart are placed below and in front of both. In form and struct uro the bronchi resemble the trachea; flattened and deficient in cartilage behind, they possess all the other tissues in com- mon with it ; the right one possesses five or six annular pieces, the left nine or ten. Their arteries are derived from the bronchial branch- es of the aorta, and their veins open into the azygos or intercostals. As the bronchi proceed into and through the pulmonary tissue impor- tant changes occur : they rapidly branch off into numerous ramifica- tions, diverging in every direction, and therefore difficult to follow individually to any extent ; each branch first divides into two, each of these again into two, and so OH, as far as we can pursue them, they adopt this dichotomous division and subdivision, though occasionally Mipernnmcrary branches arise and separate at acute angles ; finally, the small terminating tubes lead each to a separate lobule, and each ends in a free communication with its air cells or vesicles ; these air vessels are accompanied throughout by the pulmonary arteries and veins ; the for- mer are very close to and usually behind them, the veins are more loosely connected ; these different vessels can be recognized on the surfaces of a section of the lung. The air vessels very soon lose the form and struc- ture of the trachea and primary bronchial tubes ; the fibrous and mu- cous coats continue through their entire course ; the longitudinal elas- tic tissue soon disappears, but the cartilages are curiously modified and changed in a gradual manner ; instead of forming large segments of a circle, they soon become divided into small curved pieces equally diffused round the whole tube, which now becomes cylindrical ; these .-egments are of the most varied forms, and are bounded by edges and points which can mutually overlap and glide upon each other; the muscular coat is also continued circularly, and forms a thin, circular tunic, like that on the intestine; the fibres are attached to the margins and points of the cartilages ; by this means the capacity of the tubes can be changed, particularly diminished, but not obliterated ; this ar- rangement continues even in the smaller tubes, but the cartilages gra- dually lose the curved angular form, and are reduced in size to mere lines, patches, or grains, and, finally, at the last bifurcation of an air tube, a small cartilaginous tubercle stands in the angle of division ; beyond this, the tube is wholly membranous, and, as well as the cells into which it opens, appears to be composed of nothing more than the mucous lining and a fine fibrous investment. How far the muscular coat extends, whether it ends abruptly at the last cartilaginous tubercle, or whe- ther it is continued, of great delicacy, over the final tube and air cells, is is impossible to speak with accuracy or confidence ; it is probable, however, that as soon as the cartilages cease, the muscular structure which was designed to act on them, and thereby to alter the diameter of the tube, ceases also ; but as to the final tubes and cells, there being no resisting medium in these, muscular struct tire might prove injurious rather than beneficial ; the air once inspired ever afterwards retains e in a more or less distended condition, and cannot wholly be ex- p'.-lkd during the healthy state of the organs, but is constantly under- 104 DUBLIN DISSECTOR. going a gradual change and gradual displacement, by the admixture of fresh air in each inspiration, and by the expiratory efforts. The respiratory tube, from the glottis above, to the terminating pulmo- nary 7 air vesicles below, presents a curious series of transition structures, each change being wonderfully adapted to a special purpose: the larynx, in one part, with its delicate and beautiful locomotive appara- tus and voluntary endowment, and in another composed of the un- yielding and, of course, unchanging circular wall of the cricoid carti- lage ; the trachea and bronchi, with their crescentic and elastic plates, convex on all sides exposed to pressure, but deficient behind, and thereby capable of yielding to expansion, and recoiling by elasticity, aided by the transverse involuntary muscular fibres attached to their extremities ; the pulmonary tubes, cylindrical and muscular, at the same time studded with a sufficiency of cartilaginous grains to prevent obliteration, and yet to admit of change of place and form ; and lastly, the capillary air tubes and air vesicles, wholly destitute of these two elements. These modifications of structure in the different sections of this one tube, are not only interesting to the anatomist and physiolo- gist, but are also of extreme importance to the pathologist, in con- nexion with the nervous and structural diseases of the respiratory organs. Behind the trachea, the oesophagus is next seen entering the thorax, lying close to the spine, or rather to the left longus colli muscle ; its course is slightly tortuous, like an intestine, at first a little to the left of the mesial line, afterwards to the right of that line, and as it descends through the posterior mediastinum, it again inclines to the left and a little forwards. On the left side of this tube, the thoracic duct is seen ascending from the thorax into the neck, between the left carotid and subclavian arteries. As the o?sophagus enters the chest, we observe on either side of it the recurrent nerve ; that of the left side passes out of this cavity, that of the right arises on a level with this opening. The oesophagus is a musculo-membranous tube, extend- ing from the pharynx to the stomach ; it commences behind the cri- coid cartilage, opposite the fifth cervical vertebra, and enters the ab- domen between the crura of the diaphragm. In its cervical portion the trachea is anterior to it, also the left lobe of the thyroid gland, and the inferior thyroid vessels, and recurrent nerve of the left side ; the sheath of the cervical vessels is related to it laterally ; and it is sur- rounded by loose cellular membrane, which connects it to the longi colli muscles. In the thorax it soon enters the posterior mediastinum, where it has been already examined. It is composed of muscular, mucous, and cellular tissue ; the muscular is very distinct, the fibres externally are longitudinal, internally circular ; both are more distinctly marked than in the digestive canal below, excepting in the rectum, to which it bears some analogy ; they are red above, pale below, and expand on the stomach ; these fibres belong to the involuntary muscles; cellular tissue connects them to the mucous or lining coat, which is thin avid pale, thrown into longitudinal plica-, and lined by a line mm. IN !>I->I:ated coagulable lymph is found loosely connecting it to the heart ; this sometimes has a reticulated or lac-like appearance, and portions of it float on the serous fluid which exists in the cavity. In some large quantities of pus are formed, without any appearance of ul- ceration, but always accompanied with a thickened state, and a depo- sition of coagulable lymph on the internal surface of the membrane. The presence of a small quantity of fluid in the pericardium after death, is not to be set down as a morbid appearance, or confounded with the disease called hydrops pericardii, as in every healthy body a few drachms of fluid are found in the bag of the pericardium, arising from the condensation of the natural exhalation, which exists in all serous cavities, or from the transudation of the blood from the contrac- tion of the heart after death. The HEART, the central organ in the apparatus for the circulation of the blood, is a strong muscular bag, divided into four compartments, the right and left auricles, and the right and left ventricles, and is designed to receive and to propel the blood from and to all parts of the body. The heart is of great importance in zoological science, as upon its presence or absence, its simple or complex structure, many circum- stances in the general organization of an animal depend. A perfect heart exists in all the vertebrata, but differently modified in the diffe- rent classes. Mammalia and birds possess a perfect, single, but qua- drilocular heart ; in reptiles and fish it is much more simple, orbilocular, tlvat is, it consists of a single auricle and ventricle, which latter in fish 108 DUBLIN DISSECTOR. is wholly pulmonary, or branchial, but in reptiles is both pulmonary and systemic. This organ exists in mollusca also, but in a simpler or more rudimentary form ; in some there are two, or even three sepa- rate hearts placed in different parts of the animal, to regulate and assist the circulation of its blood. In mammalia and birds, notwith- standing the heart appears as single, it is yet really double, and to a certain degree symmetrical, the right heart being connected with the venous and pulmonary circulation, the left with the arterial and sys- temic or aortic circulation ; hence the synonymous terms, right or pul- monic heart, left or aortic. In man the right heart is also anterior to the left. The heart is of a well known form ; the cone is not uniformly rounded, but is a little flattened anteriorly, as well as inferiorly, hence it presents distinct surfaces and edges, besides a base and apex. It is situated in the cavity of the thorax, near its centre, and corres- ponds to the union of the superior third of the body with the two infe- rior thirds ; placed in the middle mediastinum, behind and a little to the left of the sternum, obliquely in front of the spine, between the lungs, and above the diaphragm, which separates it from the liver, stomach, and spleen ; in this position it is maintained by the pericar- dium, the pleurae, and the large vessels passing to and fro ; it is, how- ever, subject to slight changes of position from natural or healthy causes, such as change of posture of the body, as it reclines horizon- tally, or is bent forward, or to either side, also according to the diffe- rent states of inspiration and of expiration ; the condition of the stomach, and other abdominal viscera may also exert some influence in this respect. The heart is placed obliquely from above and from behind, downwards, forwards, and to the left side ; the base looks upwards, backwards, and to the right, and corresponds to the front and right side of the mesial line of the fifth, sixth, and seventh dorsal vertebrae, it often extends in front of the fourth also, as well as of the eighth ; the base lies obliquely across the spine, and is therefore well supported by it, though separated from it by the parts in the posterior mediastinum. The apex is directed downwards, forwards, and to the left side, corresponds to the costal end of the sixth rib ; the lung being notched in this region, its pulsations can be felt through the fifth and sixth intercostal spaces, below the mamma. The axis of the heart, that is, a line traversing the apex and centre of the base, has an oblique course from the point, upwards, backwards, and to the right side, or towards the right scapula. The heart, or rather the ventricles, present, for our more minute examination, three surfaces, anterior, inferior, and posterior ; two edges, anterior thin, posterior thick ; also the base and apex. The anterior surface is the largest, flattened, and slightly convex, divided into two unequal parts by a longitudinal groove, which contains the left coronary artery imbedded in fat ; there is a similar groove on the posterior surface, which also contains a branch of the left coronary artery ; these two grooves correspond to the septum between the ventricles, and meet at the apex, 109 and divide the heart into the right, or anterior, and the left, or posterior. That portion of the anterior surface to the right of the anterior line, or groove, is larger than the left, and is formed of the rig-lit ventricle; to the touch this feels soft and flaccid, and corresponds to the sternum, while the left portion is linn and resisting, and is composed of the wall of the left ventricle, and is opposite the left costal cartilages. On this anterior surface a small white spot, of variable size, is often to be seen, sometimes two or three, probably owing to the thickening of the serous or sub-serous tissue, the result of some slight inflammatory action. The inferior surface is flat and horizontal, of a triangular shape, is formed of the right ventricle, and rests upon the diaphragm ; this surface is distinguished from the anterior by the thin edge of the heart, but is gradually rounded off into the posterior ; the latter is thick and convex, is formed of the left ventricle, and rests on the inner side of the left lung ; it is separated from the anterior surface by the left or thick edge of the heart, but is so continuous with the inferior that they are regarded by many as forming but one surface. The edges of the heart are two: the inferior or anterior is thin and nearly straight, or horizontal : it extends from the inferior cava to the apex, and fits into the angle between the anterior and inferior portions of the pericardium. The posterior, or left edge, does not deserve that name; it is thick, rounded, and vertical, is formed by the left ventricle bending round from the front to the back part of the heart. The base presents from right to left the two auricular processes, and the roots of the pulmonary artery and aorta; the pulmonary artery arises on the right side of the anterior cardiac groove ; that portion of the right ventricle from which it ari>es is prolonged up wards and a little to the left side, and, contract- ing into a funnel form, is named the infundibulum ; the artery then passes backwards and to the left side; on a plane behind this is the root of the aorta from the left ventricle, at first concealed by the infun- dibulum and by the root of the pulmonary artery; this vessel soon emerges from behind the latter, and appears prominently to its right side, so that these two great arteries cross obliquely, like the limbs of the letter X ; on a plane behind these we find a circular groove separating the auricles from the ventricles ; with this the ante- rior and posterior vertical grooves communicate ; this groove is very deep posteriorly, where it lodges the coronary vein and branches of the coronary arteries ; at the bottom of it we see the fleshy base of each ventricle folded in, as it were, to present a broad surface of support to the auricles ; this surface is cut off very obliquely from before back-" "uards and downwards, so that the anterior surface of the heart is nearly an inch longer than the posterior; in front of the anterior part ot'this groove, tiie two great arteries spring, the aorta being posterior, and nearest to the groove. There is generally, but especially in old persons, a considerable quantity of fat in this groove, as also along the whole course of the coronary arterie.s. The apex of the heart is often curved a little backwards, is formed in the adult wholly by the left 110 DUBLIN DISSECTOR. ventricle, but in the foetus the right also enters into it, hence, at this age, the point is rounder, and often a little bifid from the notch uniting the two vertical grooves ; this notch in the adult is filled by fat, and requires dissection to unfold it, it then lies to the right side of the apex. The heart is larger, and more muscular in proportion in the child than in the adult; in the former, also, there is no fat upon its surface, and in the adult but little ; but in the elderly it increases, particularly on the surface of the right ventricle, on the anterior thin edge, and in the course of the coronary vessels ; there is seldom any quantity of this deposit on the auricles. The heart consists of four ca vit ies, two ventricles arid two auricles ; these the student may examine in that order or course which the blood pursues in passing through this organ. Suppose the two verne cavje pour their blood into the right auricle, so as to distend it, the parietes of this cavity then con- tract, and empty its contents into the right ventricle ; this next propels the blood into the pulmonary artery, the branches of which convey it through the lungs ; from these organs it is returned by the four pul- monary veins, two on each side, into the left auricle ; from this cavity it is forced into the left ventricle, which then propels it into the aorta, through whose branches it is conveyed to all parts of the body, whence it is again returned to the heart 'by the veins. The superior vena cava is seen descending obliquely forwards and inwards within the pericardium, and joining the upper and back part of the right auricle. Of the inferior cava but a short portion is seen within the peri- cardium ; this vessel lies on a plane posterior to the superior cava, and passing obliquely upwards, backwards, and inwards, joins the lower and back part of the auricle ; as these two veins have different aspects and are on different planes, the descending column of blood does not fall perpendicularly upon the ascending. Between these two veins the right auricle is situated; it is somewhat square; if distended it becomes convex anteriorly and to the right side, and concave poste- riorly towards the root of the right lung, also internally towards the septum auricularum ; its largest diameter is from right to left and from before backwards ; it is broadest behind and below, and is prolonged anteriorly and superiorly into the appendix, or process called the auricle ; this is loose and free, more or less serrated on its edges, turns forwards, and lies between the upper part of the right ventricle and the aorta. The right and posterior portion of the auricle is connected with the two cavae, which are here continuous with each other, the expansion of the outer and posterior walls of which may, indeed be re- garded as forming this region of the cavity, and which, therefore, has been named the sinus of the auricle, or the sinus venosus; this divi- sion into sinus and proper auricle is more perfectly marked in the left auricle ; the right auricle is connected inferiorly to the right ventricle, and partly rests on the diaphragm ; on the right side it is free, and on the left it is connected to the left auricle ; lay open this cavity by a perpendicular incision from the superior down to within half an inch of the inferior cava, from the centre of this make a transverse cut towards I>ISM: IOK. Ill tin.; anterior part of the auricle, washout tin -blood; we may then ob- serve at tlu- back part of the sinus the <>jn II'IIKJX of the two eava?. and between thecrculinn Loircri ; and in the auricular appendix the muscular fibres called iniixritli pectinati. The opening of the superior or descending eava is at the upper and posterior angle of the sinus, circular, without any valve, and directed towards the passage into the right ventricle; a projecting muscular band separates it from the auricular process. The orifice of the in- ferior or ascending eava is larger, and on a plane posterior to that of the superior ; it looks towards a remarkable depression, the fossa ova- lis, and is partially protected in front by the semiluuar valve of Kus- tachius. The tubercle of Lower projects from the right and posterior aspect of the sinus, between the two cavse, and opposite to the auri- culo-ventricular opening, and just in front of the right pulmonary vcfls; this was supposed to be of some use in directing the streams of blood from the two veins towards that opening, and preventing their perpendicular pressure against each other ; it appears to be pro- duced by a slight increase of thickness in that part of the wall of the sinus, together with a little fat externally, it is, however, very varia- ble, and sometimes indistinct, or even altogether absent. The mus- ritU pectinati are those muscular fibres which line the anterior por- tion of the auricle and the appendix, internal to the venae cava? ; the fascicidi pass from the auricle to the ventricular opening, chiefly in a parallel direction, leaving interstices between them, and from some fan- cied, but slight resemblance to the teeth of a comb have been thus named ; in these interstices there is no muscular fibre, and the investing and lining membranes are in such close apposition, that the blood can be seen through them before the cavity was opened, or if the cavity be perfectly empty, these interstices appear as whitish lines, hence the auricle always presents a striped or variegated appearance externally, whereas the sinus possesses a dense, muscular wall, and is therefore uniformly opaque. The musculi pectinati are crossed irregularly by smaller fasciculi, which give rise to a reticulated mus- cular structure, such as is seen on the inner surface of the ventricles. The left or internal side of the auricle is formed by a thin sheet of membranous and muscular substance, the septum auricularum ; on the inferior part of this we may observe a depression, the fossa ovalis, immediately above the inferior cava, and surrounded hi part by a thick lip, named its annulus ; at the upper and deeper part of this fossa we frequently find, even in the adult, a small oblique passage leading into the left auricle, its obliquity, however, prevents any com- munication taking place during life ; in the foetus before birth, this was a free opening, the foramen ovale, between the two auricles. An- terior to the opening of the inferior cava, we observe the semilunar fold of the lining membrane, the Eustacliian valve : this valve is con- nected by its convex edge to the angle between the vein and auricle ; its concave edge is loose, and looks backwards and to the right side ; its superior cormi is connected to the anterior or the left limbus of the 112 DUBLIN DISSECTOR. fossa ovalis, and the inferior to the forepart of the vena cava, and is sometimes continued round that vessel to the posterior limbus of the fossa ovalis ; in the adult and old this valve is often reticulated and imperfect ; in the foetus it is generally more perfect and large, hence it is considered by many as being of use at that period in directing the blood from the inferior cava at once into the left auricle through the foramen ovale, and preventing its mixing with that from the superior cava. To the left side of the Eustachian valve, between it and the ventricle, is the orifice of the coronary sinus, a small thimble-like cavity with muscular walls, which is also partly covered by a semi- lunar fold of membrane, the free and concave edge of which is directed upwards; beneath this, open two or more of the coronary or cardiac veins ; this fold, or valve (valve of Tliebesius), secures these openings against the re-entrance of the blood during the contraction of the auricle ; this valve is also often imperfect ; on different parts of the auricle small ori- fices may be often seen {foramina Thebesii) ; some of these are proba- bly the extremities of small veins, others only lead into the muscular depressions : anteriorly and to the right side of the venae cava?, the au- ricle presents the pectiniform and recticular structure already alluded to ; the latter structure is also continued through the auricular appen- dix, or process, which communicates by a free, circular opening with the general cavity ; the distinction between the auricle and the appen- dix is not so well denned on the right as on the left side of the heart. Inferior to this process, and opposite the tuberculum Loweri, is the large orifice leading into the right ventricle ; this, the right auriculo-ventricu- lar opening, is circular, and surrounded by a dense Avhite line, whicli is usually designated as the right tendon of the heart. We may next examine the right ventricle : for this purpose open its cavity, by raising the anterior wall in the form of a flap from below, making one incision along its right side, and the other near the septum cordis. The right ventricle occupies the anterior, inferior, and right side of the heart; of a triangular form, its base is joined to the auricle and pulmonary artery, its apex is a little short of the apex of the heart; its walls are thicker than those of the right auricle, but thinner than those of the left ventricle, it is also thinner towards the apex than at the base ; its anterior and inferior walls are much thinner than the left or posterior, which is the septum ventriculorum, and which is thick, convex, and resisting, Avhereas the other sides are weak ; hence the parietes of this cavity always feel soft and flaccid ; they are rendered very irregular internally by numerous muscular projections, the car- nets columncK ; some of these are attached throughout their whole length, others are fixed by their extremities, and loose in their centre ; these are the most numerous, they subdivide and form numerous areoLe ; and a third, musculi papillares, are fixed by one end to the fleshy substance of the ventricle, by the other to thin tendinous cords which are attached to the auricular valves ; the earner columns take various directions, and are all covered by the fine lining membrane of the heart, they form a very intricate net work on the walls of the DUBLIN DISSECTOU, 113 ventricle, and several cross the cavity ; they are less numerous on the M'ptum and at the base than near the apex. At the base of the right ventricle we observe the auricular and arterial openings ; the latter is superior, anterior, and to the left side of the former; from the margin of the auricular opening a fold of the lining membrane descends into the ventricle ; the inferior loose edge of this valve divides into three principal portions, each ending in a very irregularly notched margin, to which the chordie tendineaj are attached ; these are the tricuspid valves ; one division is to the right side, the second is posterior, on the septum cordis, and the third, which is the largest, is anterior and to the left side, and separates the auricular from the arterial opening ; this (the septum of Lieutaud) is supposed to act as a valve on the pulmonary artery, so as to prevent the blood entering it during the tilling of the ventricle ; many of the tendinous threads are connected to the dorsum, as well as to the edge of these folds, and cross each other as they run to the carneae columnae ; some also are inserted into the septum ; the edges of the valve are often studded with reddish tu- bercles. Most of the tendinous threads arise from the carneae co- lumnae, or musculi papillares ; though slender, they are very strong, and in their course to the valves they diverge, often bifurcate, and com- municate together. The left, or anterior valve or curtain, is the lar- gest, and prevents the filling of the pulmonary artery during the distention of the ventricle, or the systole of the auricle ; the cords of this valve are inserted into a long fleshy column, which is attached to the anterior, or the yielding wall of the ventricle; from the lower part of this column a transverse muscular band passes across the ca- vity to the septum ; the right curtain is connected by its cords partly to the long column, and partly to a second, which is also on the ante- rior wall ; and the third valve has its cords inserted into the septum without any separate columns. The use of the tricuspid valves is to prevent the reflux of the blood from the ventricle into the auricle ; as the former cavity is being distended, the blood separates the valves from the parietes of the ventricle, and thus becomes situated on their outer side ; when the ventricle then contracts, it presses the blood against these folds, winch are thus approximated to each other, and slightly raised against the opening, so as to close it ; the earner co- lumnai at the same time contracting make tense the chordae tendinea?, and thus accomplish two objects, first, they approximate the valves ; and second, they prevent their being reversed, or thrown up into the auricle ; if, however, the right ventricle be over distended, as a consequence of impeded pulmonary circulation, the anterior more yielding wall will carry with it the columns and cords of the anterior and right valves, and thus effect an opening or passage between them, whereby the blood may regurgitate into the auricle, and thus the ventricle will be relieved ; this mecha- nism is said to answer the purpose of a safety valve :* another useful purpose also may have been designed in this peculiar attachment of this valve, namely, that the complete diastole of the ventricle * See Essay by T. W. King, Guy's Hospital Reports, vol. ii. I 1 14 DUBLIN DISSECTOR. shall clear the opening into the artery which has been closed by this curtain during the distention of the cavity. The orifice of the pulmonary artery is small, situated at the highest point, and at the left extremity of the ventricle, anterior to, and nearly an inch to the left side of the auricular opening, from which it is sepa- rated by a prominent concave muscular ridge, and by the septum of Lieutaud ; these divide the ventricle into two chambers, an auricular, which is extremely irregular, from the reticular cellular network formed by the carnese columnae, and an arterial, which is smooth and polished. Around the root of the artery the ventricle is prolonged into a sort of process, named from its form the infundibuhim, or conus arteriosus ; out of this the artery springs, being attached to the ven- tricle by, first, the reflected layer of the pericardium, continued a short distance upon the artery, and connected to it by cellular tissue ; second, by the lining membrane being continued from the ventricle into the artery ; and third, by the attachment of the middle, or yellow elastic coat of the vessel, to the firm fibrous zone, or ring, which sur- rounds and constricts the arterial opening. This, the right arterial ten- dinous zone, stands on a plane oblique from above and without down- wards and inwards, the outer edge of its upper surface is therefore the higher ; it is dense and firm, like fibro-cartilage, and appears com- posed of three semilimar roots, convex towards the ventricle ; the cor- nua are blended together, and thus one continuous circle is formed with three triangular projections towards the artery ; the intervals between these festoons are completed by the two serous membranes, with an intervening lamina of fibrous tissue, strong, but so thin as to be trans- lucent. The muscular fibres of the ventricle are inserted into the lower surface of these convex roots, and into the fibrous tissue in their inter- stices. The middle coat of the artery is connected to the outer edge of the tendinous zone, and to its anterior projections by three semicircular roots; this connexion is very close, although there is a manifest distinction between the tissues ; those fibres of the artery that are connected to the projecting cornua of the festoons form a distinct curved line, in passing from point to point, while below this they are thinner, weaker, and, of course, shorter, and correspond to three small dilatations, or sinuses, in the ailery, named sinuses of Morgagni, or Valsalva ; inter- nal to each of these sinuses is a semilunar or sigmoid valve. The sigmoid valves are three in number, one is anterior, another posterior, and to the left, and a third is to the right side ; occasionally there are but two, and very rarely four ; they consist of a duplicature of the lining membrane with some fibrous tissue enclosed ; each is attached by its convex edge to the inner lip of the upper surface of the fibrous zone, and strong tendinous fibres are enclosed in this situation ; in the concave edge also is a distinct tendinous thread, beneath the centre of which is that small, white, or yellowish corpuscle, named corpus Arantii, which thus divides this free margin into two short lunated portions ; between the concave and convex borders of each valve, finer tendinous threads exist, curving from the corpus Arantii to the border of the fes- DfUI.tN niSSKCTOR. ] 15 toon. The tendinous structure in the sigmoid valves is more deve- loped in the aorta than in the pulmonary artery ; so also are the si- nuses external to these valves.* Each of these sinuses may be deseri In 'das bounded thus : externally by the thin, bulging, eonvex, fibrous root of the artery ; internally, by the sigmoid valve ; interiorly, or towards the heart, by the narrow, oblique upper surface of the tendinous zone ; while supe- riorly or anteriorly it is open in the direction of the artery. These sinuses are better developed in the old than in the young. The sigmoid valves, though thin and transparent, are strong and resisting ; as their action is perfectly mechanical, they are named passive, in contra- distinetion to the auriculo-veutricular, which, as requiring muscular agenrv. are denominated active valves. Their use is to prevent the reflux of blood from the pulmonary artery to the right ventricle. As the blood rtows into the vessel, the valves become vertical, and are pressed towards the sides of the artery, not, however, into close con tact with them, as the puhnonic sinuses, which always contain some blood, are external to the valves ; in proportion as the diastole of the artery is perfected the valves are more vertical and more separate from the walls, and the sinuses become fully distended ; when the !e of the artery occurs the blood is pressed backwards and in- wards towards the ventricle, the valves are thereby approximated to each other, and are thrown horizontally across the calibre of the artery, towards which they are concave, while towards the ventricle they are convex, the opening into which is thereby closed, and only so much blood is forced backwards as lies between the valves, or towards the axis of the passage ; it has been thought by some, that the very axis is elosed by the meeting of the three tubercles of Arantius ; this opinion, however, is not confirmed by careful examination, for if we imi- tate their supposed condition during life, we shall find that the valves do not become perfectly horizontal, but that the edges rather overlap or press against each other ; these tubercles also are often very indis - tinct; in the young they do not project even to the edge ; they are, pro- bably, intended to give additional strength in the axis of the opening, where the reflux force will be most sensibly felt ; they may also serve as a fixed point for the tendinous threads enclosed in the folds. The pulmonary artery ascends obliquely backwards for about two inches within the pericardium, and just as it escapes from this cavity it divides into the right and left branch ; in this course it is convex forwards and to the left, lies at first anterior to the aorta, and then erodes over it to its left side. The right pulmonary artery is the longer branch ; it turns in a transverse direction to the right side, an- terior to the right bronchus, and passes through the arch of the aorta, behind the superior cava, to the root of the right lung, and there divides into three branches. The left pulmonary artery is short, pro- ceeds to the left side, and, entering the root of the left lung, anterior, and rather superior to the left bronchus, divides into two branches ; * See " Heart," by J. Pa-id, and " Aorta," by J. Hart, in Todd's Cyclop, of Aiiat. and I'hysiol.. also Anat. Generale, by Beclurd. i ' 116 DUBLIN DISSECTOR. from the division of the pulmonary artery a ligamentous cord extends backwards and downwards, in the direction of the primitive trunk, to the lower extremity of the arch of the aorta ; this is the remains of the ductus arteriosus, which in the foetus conveyed the blood from the pulmonary artery into the aorta, as it could not pass in any qtiantity through the condensed structure of the lungs ; the recurrent, or infe- rior laryngeal nerve of the left side winds round this substance. The pulmonary artery is composed of the same number of tunics as the aorta, but the fibrous coat is much weaker, therefore this vessel, when empty or divided, collapses. In the lungs the pulmonary arteries di- vide into numerous branches which accompany the bronchial tubes and pulmonary veins, the artery in general above and behind, and the vein below the bronchial vessel ; finally, the capillary terminations spread minutely on the air cells in innumerable ramifications, from which commence the pulmonary veins ; these unite with each other, and form larger trunks, which arrive at the root of the lungs, two on each side, where they lie anterior and inferior to the pulmonary arte- ries ; these veins then pass inwards to join the left auricle; those of the right side are concealed by the right auricle and superior vena cava, and open into the right side of the cavity ; the left veins are shorter, and open into the left side, a little nearer to each other ; a few fleshy fibres are continued on these vessels from the auricle, which ca- vity may be next examined. The left auricle is situated at the upper and back part of the base of the heart, in front of the posterior mediastinum ; it may be exposed either by raising the apex of the heart, or removing this organ from the body, and placing it on its anterior surface ; like the right, it may be divided into the sinus venosus, and the auricular appendix or pro- cess; the sinus is somewhat square, smaller than the right, but its parietes are thicker and stronger, and therefore more opaque ; from its anterior, upper, and left extremity the appendix passes forwards, and overlaps the origin of the pulmonary artery ; this appendix is longer, more curved, and irregularly notched than that on the right side, and communicates by a well defined opening with the ge- neral cavity. Open this chamber by a perpendicular incision along its posterior part in the middle line ; internally we perceive it smooth, except in the appendix, where a few fleshy fasciculi appear, as in the right side ; the posterior wall is flat, and corresponds to the oeso- phagus in the posterior mediastinum ; the right side is the septum auricularum, a slight depression in which, not so distinct as that in the right auricle, marks the former situation of the foramen ovale ; the four pulmonary veins are seen opening into the angles of this cavity, tAvo on each side ; those of the right are immediately be- hind the septum, those of the left open very near each other, and some- times in common, beneath the opening of the appendix ; at its inferior and anterior part we perceive the opening into the left ventricle, circu- lar, smooth, and marked by an opaque, dense, white line, as in the right auriculo-ventricular opening, than which this of the left side is somewhat smaller. DUBLIN DISSECTOB. 117 The left ventricle occupies the left and posterior regions of the heart, and forms the principal bulk of the organ ; of a conical form, the base above shorter than the right ventricle by the length of the infun- dibulum ; its point forms the apex of the heart and extends beyond the right ; it is a little longer, and apparently, though not really, smaller ; its walls feel firm and resisting, and do not collapse, though empty. Continue the incision already made in the left auricle, down- wards through the posterior wall of this chamber to its apex, and we shall perceive the superior thickness of its parietes, excepting near the point, where, especially in old persons, they are very thin, a fact which accounts for rupture of this cavity generally occurring in this situa- tion ; the septum cordis appears to belong to this ventricle, and is concave towards it, so that this chamber appears pushed or received into the right, particularly at the upper part, from the overlapping of the infundibulum, but not so below or at the apex ; the interior is not so much, or so deeply reticulated as the right, except near the point where it is very much so. This cavity presents also the three species of carneae columnar ; the musculi papillares are very large, but only two or three in number ; they arise low down near the apex, one from the posterior wall, near the septum, the other from the junction of the left and posterior wall ; they ascend, and about the middle of the ca- vity end in blunt points, often bifid, and sometimes trifid ; to these the chorda} tendineae are attached, which also are stronger and thicker, but fewer in number, than those in the right ; some few of these threads merely pass from one papillary muscle to another ; the others extend to the two valves of the auricular opening ; some of these di- vide and are inserted into both curtains, and from each of the muscles chords pass to both valves, so that they interlace ; they are attached not so much to their margin as to their dorsum, or ventricular surface, on which they form an expanded interlacement, and contribute much to their strength ; from this net-work some of the chordae tendineaj pass up to the margin of the auricular opening, and are inserted into its tendinous zone. The walls of the ventricle are smooth above towards the base, hi which are seen the openings of the auricle and of the artery ; the latter is smaller and directly in front of the former, and, like that of the pulmonary artery, is furnished with three sigmoid valves. The auricular opening is much larger, a little to its left side as well as behind it ; and, like that in the right ventricle, though smaller, is also provided with folds or curtains, which, however, are only two in number, and are named the mitral valves ; the auricular and aortic openings are very close, the anterior mitral valve only inter- vening ; this is so joined to the base, or origin of the adjacent or pos- terior sigmoid valve of the aorta, that if these two valves be removed the base of the ventricle will then present but a single orifice. The auricular opening is in the upper and back part of this cavity, of a circular or rather oval figure, its long axis transverse, and therefore nearly at right angles with the axis of the right auricular opening, which is longer and directed from before backwards ; it is sin-rounded 118 DUBLIN DISSECTOR. by a white and dense tendinous zone, from which a fibrous expansion descends, enclosed in the valvular duplicature of the lining membrane, the latter soon divides into two principal segments, one anterior and a little towards the right, the other posterior to this foramen and some- what to the left ; the anterior mitral valve is much larger, and directly intervenes between this and the arterial orifice, and, like the septum of Lieuteaud, in the right ventricle, divides this also into an auricular and an arterial chamber, and which can only communicate below this valve ; this larger curtain also is supposed to answer the purpose of preventing the influx of blood into the aorta during the diastole of the ventricle ; this object, however, is also secured by the aortic valves, for during the ventricular diastole the artery is in its state of systole, and, of course, is closed by the sigmoid valves, which are then across the mouth of the vessel. The posterior, or left curtain is shorter and more fixed, as one or two tendinous threads pass from its dorsum to the wall of the ventricle ; both these curtains are strengthened not only by the fibrous expansion they enclose, and by the tendinous interlacement on their ventricular surface, but also by containing, particularly the anterior one, firm cartilaginous tubercles, and even not unfrequently bony laminae, the former near their margin, the latter near the base. The mitral valves are stronger and more efficient as such than the tri- cuspid, and their office is analogous : as the blood descends into the ventricle, they are separated from the axis of the opening, and the larger is pushed beneath and across the mouth of the aorta ; as the diastole of the ventricle is perfected, the blood fills every recess, and, of course, occupies the spaces between the valves and the walls of the cavity ; in the systole of the ventricle they are approximated, and the papillary muscles, which must also contract, draw these curtains closer and closer, so as gradually to convert the opening into a narrow conical passage, the apex below, and finally to close it, while at the same moment that leading into the aorta is opened freely for the entrance of the fluid. The contractile efforts being directed upwards towards the base, accounts for the thinness of the apex contrasted with the muscular wall in the centre and above, at the same time it explains why, in cases of obstruction to the circulation, from any morbid cause, the former usually yields, and not unfrequently ruptures of a sudden. The opening of the aorta is directly in front and a little to the right of the auricular ; leading to it, the surface of the ventricle is smooth, white, and polished ; within the contracted orifice are seen the three semilunar valves, one anterior, another to the left, and the third to the right side. The attachment of the aorta to the ventricle, and the structure of its valves and corresponding sinuses, are so perfectly simi- lar to those of the pulmonary artery, which have been already so mi- nutely examined, that it would be superfluous to repeat the description of such analogous parts ; it is only necessary to observe, that all the tissues in the aorta are stronger, the tendinous ring from which it springs is more distinct and prominent, the sinuses of Valsalva, or Morgagni,' more developed, the sigmoid valves larger and thicker, and m Bl.l.N l>I.-.->iXTOK. IJ'J tin' rorpm-a Arantii in particular are much more prominent. Above the five margin of the anterior and leftsigmoid valves are the orifices of the right and left coronary arteries, the nutrient vessels of the heart ; if we press the valves against the sides of the artery, into that position hi \\ InYh \ve may suppose them placed in the systole of the ventricle, we shall find that they do not close or cover the mouths of these vessels, we may therefore inter, that the coronary arteries of the heart are tilled synchronously with all the branches of the aorta. The root of the aorta is implanted into the anterior angle between the two auriculo-ventricular tendinous zones, and its posterior half is intimately connected to both; its anterior portion is directly over the septum veutrieulorum, which at this spot is thin ; the root of the aorta occupies a portion of that space which intervenes between the origin of the pulmonary artery and the right auriculo- ventricular zone, while that of the pulmonary artery from the infundibulum is superior, anterior, and a little to its left side ; these two roots are very close together, being only separated by the upper thin edge of the septum cordis ; in a horizontal section of the heart made on a level with the base of the ventricles, when the organ has been removed from the chest, the four great openings will be found to have the following relations to each other from the right to the left side : first, the right auriculo- ventricular ; second, the aortic ; third, the pulmonic, also on a plane anterior to all ; and fourth, the left auri- culo-ventricular ; and as the auricles are posterior to the ventricles, their openings are behind the arterial, and their zones are conjoined towards the mesial line, while the arteries springing from the forepart of the ventricles appear to issue more from the centre of the heart, the auricular sinuses being behind, while the appendices bending forwards overlap them in front. In the common central point of attachment, between the root of the aorta and the two auricular tendinous rings, we find a dense, compact, fibrous, and even sometimes a cartilaginous tissue, of somewhat a semilunar form ; this serves as a firm and incom- pressible point of support for these three great openings, and of at- tachment and action for the muscular fibres. It is in this very- situation in the larger ruminantia that we find a distinct and perfect bone is placed ; and in the same place, too, we not unfrequently detect in the very aged heart of man, earthy and perfect ossific deposits, which sometimes extend even into the mitral valves, particularly the anterior one, and, if small, without impairing then- mobility ; one example, among many others that might be adduced, of abnormal appearances in the human subject being, as it were, repetitions of, or degenerations into forms and structures winch in other animals are the normal and the determined conditions. It has been just before observed, that the roots of the aorta and the pulmonary artery are very close together, the superior edge of the septum ventriculorum alone intervening ; hi the very young embryo this septum does not exist ; it commences be- low and increases upwards, unlike the septum auricularum, which de- scends, assisted by the valve of the oval hole which rises from below. Tlie last part of the septum cordis to be formed is the upper edge which 120 DUBLIN DISSECTOR. is immediately beneath the two great arteries ; previous to the deve- lopment of this septum, these vessels arise by one common tube, and this by the growing and ascending septum ultimately becomes subdi- vided into the pulmonary artery in front, and the aorta behind. These facts explain certain irregularities in these parts which we occasionally find in the infant, still more rarely in those of maturer years, such as a communication between the ventricles ; when this exists it is found at the upper part of the septum, and may be considered as the result of some delay or arrest in the growth or completion of this partition ; the same explanation will account for the aorta in some cases arising by a double origin, or rather springing out of both ventricles, as also for the aorta and pulmonary arising by a common stem, or, though rising distinctly, yet having a communication close to their roots. These and many other deviations from the established plan, and which may be regarded as abnormal, when found in the matured foetus, and which are usually incompatible with any long continued indepen- dent existence, were yet, however, in all cases, at an earlier period, then* actual, though but their transient condition; and it appears equally interesting to remark, that many of these peculiar conditions which are only temporary in the foetus, and which are considered abnor- mal when continued in the adult, are, in most of the class Reptilia, the normal, the permanent, and the necessary arrangements. The aorta at its origin is covered by the infundibulum and the pul- monary artery ; it ascends obliquely forwards and to the right, as high as on a level with the cartilages of the second rib of each side ; it then passes backwards, and to the left side ; and lastly, descending as low as the fourth dorsal vertebra, it becomes closely attached to the spine ; this portion of the aorta is called the arch, at the termination of which this vessel receives the name of thoracic or descending aorta, which descends through the posterior mediastinum, as was already stated. The arch of the aorta [is divided into the ascending, the transverse, and the descending ; the first is the longest portion, and in general is so much dilated at the upper and convex part as to have received the name of the great sinus ; this ascending portion is within the pericar- dium, covered at first by the pulmonary artery, it afterwards lies be- tween this vessel and the vena cava ; from the commencement of this the two coronary arteries arise ; the middle or transverse portion of the arch lies above the pericardium and in front of the trachea ; from it arise the innominata, left carotid, and left subclavian ; the descend- ing portion bends behind the root of the left lung, and is connected to the pulmonary artery by the remains of the ductus arteriosus ; through the arch of the aorta, the right pulmonary artery, left bron- chus, and left recurrent nerve pass. The heart is composed of several tissues, first, the reflected serous layer of the pericardium ; secondly, the muscular fibres which consti- tute the greater portion of the organ ; thirdly, tendinous and fibrous structures, which are only found at the four orifices in the heart and in the four sets of valves connected therewith ; fourthly, a fine lining DUBLIN DISSECTOR. 121 membrane, in many respects resembling the serous membranes ; and fifthly, the common elements of all organized parts, viz., cel- lular tissue, vessels, and nerves. The external serous membrane has IHVII already described ; it is thicker and more easily admits of sepa- ration on the auricles, and on the roots of the large vessels, than on the ventricles. The inner membrane is termed the Endocarde ; it may be traced from the entrance of the two venae cavse, the inner coat of which it forms, into the right auricle which it lines throughout, forms the Eustachian and the coronary valves, is smooth and polished, and ad- heres to the muscular fibres by such a close and fine tissue, as to be difficult of demonstration ; it then passes through the right auriculo- ventricular opening, adheres closely to its fibrous boundary, increases in density, and forms the loose, pendulous valve, named tricuspid, from the root of which it is expanded over the inner surface of the ven- tricle, of such extreme fineness as to be perfectly transparent, involving all the carnese oottnmue and coating all the areola? between these ; as it approaches the orifice of the pulmonary artery it is stronger, adheres to the line of its origin, assists in forming the sigmoid valves, and be- comes continued into the lining internal coat of that vessel and of its ramifications. In like manner, through the left cavities of the heart, we can trace it from the pulmonary veins into the left auricle, thence into the left ventricle and aorta, forming in its course the mitral and the sigmoid valves. The endocarde is thicker in the auricles than in the ventricles, and more so in the left than in the right ; its smooth and polished appearance causes it to be ranked as a serous membrane, with some characters, however, peculiar to itself. It serves to connect the muscular fibres together, and, in the auricles especially, to complete the walls in their interstices ; by its duplicatures it also forms the cur- tains in the valvular apparatuses at the different openings, while its smooth surface facilitates the passage of the blood through the cham- bers of the heart, and prevents its adhering to any of the irregularities they present ; analogy renders it more than probable (though difficult to determine), that this membrane, not only in the heart, bnt through the whole vascular system, exhales some fine vapour which must faci- litate the circulation of the blood. The structure of the heart and the roots of the large vessels are sup- plied with blood by the two coronary arteries, the openings of which from the aorta have been already noticed as just above the edge of the anterior and left sigmoid valves and sinuses ; these vessels can be traced without much dissection ; dividing the infundibulum will expose their origin, and their course is seen by removing the serous membrane and the cellular and adipose tissue in the cardiac grooves. The right coronary artery supplies the right auricle, the posterior I tart of both ventricles and the thin edge of the heart ; it arises from the fore- part of the aorta, above the anterior sigmoid valve, and appears between the infundibulum and the right auricle, sinks into the auriculo- ventricu- lar groove, winds round to the back part, sending a long branch along 122 DUBLIN DISSECTOR. the anterior thin edge of the heart which reaches to the apex, and then, opposite the posterior vertical groove, it ends in two branches, one descends in this groove along the back of the septum to the apex, and forms a vertical circular inosculation with the left coronary ; the other continues round in the superior sulcus, and, meeting the left ar- tery, forms a superior circular inosculation at right angles with the former ; this horizontal coronary inosculation is partly concealed by the trunk of the great coronary vein. The left coronary artery is somewhat smaller ; it supplies the left auricle, left ventricle, and the septum ; its origin is concealed by the infundibulum, but it soon appears between this and the left auricu- lar appendix, descends a little to the left, and divides into an inferior and superior branch ; the latter is the smaller, it winds round in the auriculo- ventricular sulcus to the back part of the heart, and meets the circular branch of the right ; the other branch, which is inferior, anterior, and the larger, descends tortuously in the anterior vertical groove as far as the apex, where it joins the branches from the right ; in this course it supplies the left ventricle and the septum cordis ; the coronary arteries communicate freely and frequently, not only in the two circles already mentioned, but by numerous branches on the aorta and pulmonary artery, on the surface and in the substance of the parietes of the heart. These arteries are frequently found spotted with calcareous grains, and sometimes as contracted rigid tubes ; in such cases the muscular structure of the heart appears pale, flaccid, and atrophied ; they also often present a flattened and a whitish aspect ; sometimes they appear a little dilated and very tortuous, and sur- rounded by serous infiltration ; I have seen them sh'ghtly varicose ; in an old person they are usually imbedded in fat. The cardiac veins do not exactly correspond to the arteries ; there is but one considerable vein, and this does not accompany either ar- tery through its entire course. The cardiac veins are great and small. The great or the coronary vein commences in a number of small branches about the apex, ascends in the anterior vertical groove, receiving anterior cardiac branches, both superficial and deep, and, in- creasing in size, it turns round the base of the heart, first to the left and then to the back part, lying in the left auriculo-veutricular sul - cus, superficial to the superior arterial circle ; in this situation it re- ceives posterior cardiac branches, auricular, ventricular, and interven- tricular, and appears oftentimes so dilated as to have received the name of coronary sinus ; it then opens into the posterior inferior part of the right auricle, to the left of the inferior cava, being pre- viously dilated into a sort of ampulla ; the opening is concealed by a semilunar valve, beneath which the orifice may be seen in a sort of smooth, deep sinus, and close to it very frequently are two or three other small venous openings. In the vertical part of its course it receives both deep and superficial branches from the ventricles and their septum, in its circular portion it receives a very large branch (the left cardiac vein), which ascends from the apex along the left side, DUBLIN DISSECTOR. \~2.J then, passing backwards over the corresponding artery, joins it at right angles : the coronary vein next receives several brandies from the back part of the left auricle, and from the back of the left ventricle ; a considerable one, also, from the septum cordis joins it near its termi- nation, but frequently opens distinctly into the auricle in the same sinus and beneath the coronary valve. The. small cardiac n-i/tv, -which are two or three in number, also one from the anterior edge of the heart (the vena Galeni), are si- tuated on the anterior surface of the right ventricle, and often open separately into the lower part of the auricle ; these veins return the blood from the anterior surface of the organ, while the great coronary returns it from the left and posterior regions, from the septum, and partly also from the anterior or right surface of the heart. The car- diac veins want valves except the single semilimar fold in the right auricle, but this is seldom a perfect valve ; injections can very generally be made to pass from the cavae through the auricle into this vein, and so till all its branches; during life, however, the contraction of tbe surrounding muscular fibres may assist this valve in closing the subjacent sinus against regurgitation ; this point, however, may be considered as doubtful, for the valve is often defective, and the circular portion of the vein is occasionally found considerably dilated; in such cases, most probably, regurgitation may have occurred during life, as it does into the veme cavae, especially if there have been any obstruction to the pulmonary circulation. The nerves of the heart are derived from the sympathetics, par vagum, andrecurrents ; the branches arising from these different sources are soft and grey, they all converge to the concavity of the arch of the aorta, and form, in front of the trachea, the cardiac plexus, which is a very entangled network of filaments, usually enclosing one or more masses of small, irregular-shaped ganglions ; the chief cardiac nerves arise on either side of the neck from the superior, middle, and inferior cervical ganglions, and are named accordingly the superior, middle, and inferior cardiac nerves, they are, however, very irregular in number and size, and often so indistinct as not to conform to any given description ; frequently there are only two on the left side ; t!i"~e nerves are joined above by many delicate filaments from the par vagum, and lower down by several large branches from the re- cunvnts. From the great cardiac plexus pass off two principal divi- sions, each of which forms a plexus surrounding either coronary ar- tery ; these are named the coronary plexuses, right and left, the latter is the larger, and supplies the left side of the heart ; they con- sist of numerous very fine filaments which accompany the ramifica- tions of the arteries, and can be traced as white lines, on the surface of the heart, beneath the serous membrane, fora considerable distance from the base towards the apex, and finally they enter into the mus- cular structure along with the capillaries, by such minute fibres, that the eye cannot determine their exact mode of termination ; the greater number are distributed to the ventricles and but comparatively few 124 DUBLIN DISSECTOR. to the auricles ; if the heart have been previously boiled or macerated in spirits, their course can be more easily traced. (See Nervous System.} The fibrous and tendinous tissues in the heart have been already par- tially noticed ; they exist at the four orifices, in the valves, and chordae tendineae; they form a sort of framework or foundation for the attach- ment of the two great arteries, and for the support of the muscular struc- ture. Each auriculo-ventricular opening is surrounded by a strong ten- dinous zone, to which the muscular fibres of the auricle are attached above, and those of the ventricle below ; that of the left side is stronger than the right, both are stronger and broader on the ven- tricular than on the auricular aspect, and the plane of each is oblique from before backwards and downwards ; from each an expansion is derived, which is enclosed in the mitral and tricuspid valves, and which imparts to them considerable strength and resistance ; the right margin of the left ring is closely connected to the aortic zone. The tendinous rings surrounding the arterial openings have also been already described, they are, of course, smaller, but they are firmer than the auricular, and the aortic is more so than the pul- monic ; each circle is smaller than the circumference of the artery immediately above ; from these also, tendinous expansions proceed, six in number, that is, one into each semilunar valve, and one into each of the angular spaces between the thin fibrous roots of the artery ; connected with the auriculo-ventricular valve also are the tendinous chords from the carnea; columnae, these present all the characters of true tendons, they are enclosed in the fine membrane of the ventricles, and are very distinct on the dorsum of the valves, at the root or fixed edge of which they are inserted into the tendinous rings ; some of these fibres often present a reddish appearance, probably only from being stained by the blood, at first view resembling muscular fibre, and some have supposed that such really exists in these valves, and that it even becomes occasionally much developed in certain diseases of the heart ; however, the most careful examination fails to detect any such muscular structure in a satisfactory manner in the human sub- ject, though in some of the larger animals it is manifest, and in birds one division of the tricuspid valve is wholly muscular. Tendinous fibres also exist, and have been already noticed in the arterial valves. Muscular tissue is the principal component of the heart, and con- stitutes its most essential element ; the heart, in fact, is a hollow muscle, or rather two hollow muscles, one auricular, the other ven- tricular, these are distinct, and independent of each other ; and each of these again is subdivided into two, a right and left, which in the perfect organ, are separated by distinct septa, so that the heart is truly quadrilocular ; the septa are formed of two laminae of endocarde, with an intermediate muscular stratum derived from an inflection of fibres from the walls ; the ventricular septum is very thick and eminently muscular, the endocarde being as nothing ; it appears to belong to the left ventricle, and is convex towards, or, as it were, pushed into X DISSECTOR. 125 tin 1 right ; the auricular septum is much thinner, contains but little* muscular tissue, and is chiefly composed of the lining membrane, tin* two lamina 1 of which are very distinct and strong ; this septum appears to belong to the right auricle rather than to the left, and is convex towards the latter. The cardiac muscles are usually regarded as ap- pertaining to the involuntary class ; in point of function they do so in an eminent manner, as during health and rest they act without our consciousness, but in structure they present peculiarities which dis- tinguish them from both the voluntary- and involuntary ; thus, in res- pect of colour and consistence, they exceed the involuntary, and equal, if not surpass, most of the voluntary, the latter also they resemble in possessing a distinct tendinous structure, which serves as a fixed point of attachment, or of origin and insertion, and some of the fleshy fibres end abruptly in the tendinous; many of the fasciculi also have a parallel course, as in the voluntary, yet again they constantly inter- mingle and alter their direction as do those of the involuntary muscles ; the fibres and fasciculi are much more intimately united to each other than those in either class, and the mode of their connexion constitutes one of the most striking peculiarities ; in all other muscles of either class the fasciculi are attached together by cellular tissue, but in the mus- cles of the heart there is so very little of this common vinculum, that the close connexion of their fibres must depend partly upon their compact juxta-position, and partly upon their complex interlacement. Cellular membrane is seen on the surface and edges of the organ, par- ticularly on the anterior, also around the nutrient vessels in the ver- tical grooves, and in the deep circular auriculo-ventricular channel ; in the latter it penetrates deep to the tendinous zones, as the fleshy fibres above and below this line are perfectly distinct, but along the vertical cardiac grooves it is confined to the vessels, and does not pass to any depth, there being only an indentation, but no separation or division of the muscular structure. It is not difficult to understand the design, and to perceive the special relation of this peculiar condi- tion ; this close intertexture of a considerable mass of muscular fibre in the walls, and the absence of any passive yielding material, impart a certain elasticity and a degree of strength well adapted to resist over- distention, while the alternate relaxation and contraction effected by this uniform structure is peculiarly well suited to its functions ; the cellular tissue found more or less in all other muscles admits of motion between the fasciculi themselves, and allows one portion of the mus- cle to contract, while another is relaxed, but in the heart the whole of each muscle must and does contract at once ; the fibres which en- close each ventricle, and those which connect both, act at the same moment ; the two ventricles, with their valve muscles, and septum, being synchronous in action; and so the fibres proper to each auricle, with the connecting fibres of both, act synchronously, and there can be no partial action or partial relaxation either in the superior or in- ferior cardiac muscle. From this peculiar disposition of cellular membrane on the heart, we can explain the appearances which adi- 126 DUBLIN DISSECTOR. pose deposits present, and which here, as in all other situations, have this tissue as their nidus and support ; on the heart fat is often depo- sited particularly in advanced life, and is found where the cellular tissue exists, in the circular and vertical grooves, in the course of the blood-vessels, and on the surfaces, especially the anterior, but not between the muscular fasciculi or on their internal surface ; in some instances the walls of the right ventricle appear converted into fat, but the deposit has either increased from the surface, or the structure appears to have been altogether changed, the muscle becoming soft and oily, as if it were partially dissolved or degenerated into this sub- stance ; this change is very seldom found in the left ventricle or in the septum cordis ; we may conclude, therefore, that the cardiac muscles cannot, in compliance with mere systematic arrangement, be placed in either class, but must stand alone, being muscles " sui generis" formed and endowed in a special manner and for a special purpose. The muscular fibres of the heart cannot be traced in the ordinary progress of dissection ; the organ must be prepared with care, and much time devoted to the examination ; the student will require at least two human hearts, one very young, the other adult, also the heart of an ox and calf, and of a sheep and lamb ; these must be washed free from blood ; the serous and cellular membrane, vessels, and nerves removed as fully as possible ; they should then be boiled for a short time, then macerated, and pai'tially dissected, then boiled and mace- rated again ; by repeating these processes with care, the structure will become loosened, though the fibres are hardened, and the latter may be separated, so as to render the course and arrangement of the fasci- culi tolerably evident. The muscular fibres of the auricles are independent of those of the ventricles, and are much fewer in number, hence these chambers feel weak and flaccid when contrasted with the latter; these fibres are attached to the upper narrow border of the auriculo- ventricular ten- dinous rings, also to that of the aorta, they consist in some situations of two planes, a superficial and a deep ; the first is common to both au- ricles, the latter is proper to each ; these two, however, are not sepa- rate, distinct, and perfect throughout, wherever any of the superficial fibres are deficient, some of the deep layer will supply their place, and frequently the fibres of one lamina, by a change in direction and course, will become a portion of the other. The superficial or common la- mina consists of fibres, mostly transverse, thinly expanded over the tight auricle, and attached to its tendinous ring, they pass across the septum auricularum to envelope the left, and to connect both ; on their anterior walls these transverse fibres are very distinct and strong behind the ascending aorta, towards which they present a marked con- cavity, and to which some fibres are usually attached ; towards the borders these fibres expand and separate to enclose rather than cover the appendices, and to admit the entrance of the great veins ; along the septum some fibres bend inwards into it, and surround three- fourths of the oval fossa like a sphincter : in the valve itself a few 1HB1.1N mSM-XTOR. 1 "2 7 muscular fibres may ho detected, this layer is very weak on the right aurii-le. much stronger on the left, and most distinct on the front of each. If these superficial transverse fibres be carefully divided over the septum auricularmn, and the handle of the knife insinuated into the posterior groove, we may, with much care, separate the auricles and divide the septum, provided it he complete, into two distinct por- tions, we shall then perceive the form and relative thickness of each, as also how the septum belongs to the right more than to the left, and the right auricle is convex towards the left and pushed into or received by it. The deep nniscular fibres are proper to each chamber, and are connected to the lining membrane ; arising from the aortic and auri- cular zones, they mostly take a circular course round the transverse axis, many, however, pass off obliquely or in a ramose manner, some enter the septum, some become superficial, others encircle, like sphinc- ters, the pulmonary veins, and form loops around and between them, also round the entrance into the left auricular appendix, and interlace with the superficial fibres, especially in their appendices, where their plexiform ramifications produce the peculiar reticulated texture, leav- ing interstices, wherein the internal and external serous membranes are in contact ; the course and the irregular ramifications of these fibres are best seen from the interior of the auricles, arising from the tendinous circles the columns ascend in different directions, and soon divide and subdivide, communicating and intertwining in a manner unknown in any other muscular structure, except, perhaps, in the muscular coat of the urinary bladder, which, in this one respect, bears a remote ana- logy to this arrangement. The action of the auricular muscles must be towards their fixed points, namely, the tendinous rings, they will, therefore, contract these chambers in all directions, and urge their contents through the large openings into the ventricles ; it is doubtful whether they affect the venous openings, their arrangement on the pulmonary veins would incline to the opinion that their contraction may partly propel their blood into the auricle, and during the systole of the latter may also constringe their openings, so as to prevent regurgitation into them ; the annular fibres also in the septum may, at an early age, assist the valve in the more perfect closure of the foramen ovale. The muscular structure of the two ventricles constitutes the principal portion of the heart, and gives to it its peculiar form and consistence; those lil ires, like those of the auricles, are divisible into superficial or oblique, and deep or circular, these can generally be made tolerably distinct and separate by dissection ; the superficial are common to both cavities, and the deep are proper to each, so that (as Cruveilhier -) the ventricles are two distinct sacs, enclosed in a common sac (vol. iii. p. 25). The superficial fibres are very long, and dis- posed in laminae or bands which can be separated and raised off one another, not, however, completely, as fibres pass to and fro connecting them together, and crossing or intersecting them obliquely; none of 128 DUBLIN DISSECTOK. these fibres are perfectly vertical, or perfectly transverse, they are all oblique, and the superficial are more so than the deeper ; none of them are superficial through their entire course, but only as they de- scend ; they become deep or internal as they ascend ; many of the fas- ciculi are of great length, arising from one part of the auricular ten- dinous ring, then, descending to different distances, they ascend, many of them to be again attached to the same structure. The most super- ficial fibres on the anterior surface arise from the inferior broad mar- gin of the auricular tendinous ring, descend obliquely towards the left as far as the apex, here they interlace with the corresponding fibres from the posterior surface, which, though more vertical, also descend obliquely to the right, they then ascend internal to the deep fibres, some terminate in the mammillary muscles, others ascending in the septum, and in the internal wall of the left ventricle, are again inserted into the auricular ring ; all these bands are common to both ventricles, being superficial in one, and deep-seated in another, and proceed in this spiral manner, and are broader near the base than the apex of the heart ; the superficial are longer than those deeper seated ; the ascend- ing and descending portions of each form arches or loops, convex towards the apex, and concave upwards, and each encloses a similar but shorter loop in succession, hence the walls are thicker in the base and centre than at the apex. As the superficial oblique fibres from both surfaces converge to the apex, they present in it a curious twisted vorticose appearance, both set interlacing and then ascending on the inner surface of the parietes, or in the septum ; thus the apex in its anterior and left side is formed by the fibres from the anterior or right surface, and in its posterior and in part of its right side by those from the left or posterior surface of the heart ; it consists of a number of bent or convex fasciculi, which from this point radiate upwards and in a stellate manner in all lateral directions ; when the serous membrane has been removed from this spot the interstices between these interlacing fasciculi can be expanded and stretched, the endo- carde at the same tune giving way, so that we can open into either cavity, without actually dividing any muscular fibre, because the deep layer of muscle does not descend quite to the point, hence another rea- son why the apex, especially of the left ventricle, is more liable to yield and to give way than any other portion of the parietes. The posterior superficial fibres ascend from the apex, partly in the septum, in the carneae columnie of the left ventricle, and in its posterior wall to the left auricular tendon ; but very few of the superficial fibres cross the anterior vertical cardiac groove, from the right to the left ventricle, except near the apex ; but several sink into the septum and inter- mingle with the ascending fibres, hence it is very difficult to unravel the septum in a satisfactory manner ; on the posterior vertical groove a number of fibres pass across from the left to the right ventricle and gradually bend into their course, while others pass into the sep- tum ; if the fibres crossing these two grooves be divided, we can, by patiently teazing through the septum with the handle of the knife, 129 tliviile it into two lamina*, and thus separate the ventricles ; wo shall then be able to contrast the two. and to judge of the superior thickness anil mass of the left, how it is pressed into the rig-lit, and how at the upi>er part, the inf'undibnlum, or conus arteriosus of the latter, is bent over it like the beak of a bird. If the same operation have been successfully performed on the auricles, we shall then be able to sepa- rate the two perfect hearts, and again replace them, and thus accu- rately examine the relative position of the four openings in the circular auricnlo-ventricular groove, also the position of the aortic root, be- hind and a little to the right side of that of the pulmonary artery, between the infundibulum and the right auriculo-ventricular foramen, and finally, the perfect crossing of these two great arteries. The deep muscular fibres of the ventricles are proper to each cavity ; their di- rection is generally circular, though many are spiral, and some are oblique ; they are placed between the descending and ascending por- tions of the superficial or common fibres, they are not, therefore, ex- posed to any extent, either externally or internally, without removing a portion of the latter, though internally they are in many places in contact with the endocarde ; they encircle each cavity, the superior rings are the largest, are attached to the auricular tendons, and many of the middle bend spirally to attain the same attachment ; the inferior rings diminish in size towards the apex, where they are very small and contracted ; they do not extend to the very point, and through the last and smallest rings the superficial or common fibres ascend ; each of these circular muscles is likened by Cruveilhier to a small oval barrel ; the large end above, open into the auricle, the small end be- low, a little short of the apex, open also, but occupied by the ascending common fibres. The ventricular muscles differ from the auricular in being much more fleshy, red, and strong, also in the direction of the fibres ; the superficial in the auricular being obliquely transverse, in the ventricular obliquely vertical, while the deep fibres in the former are circular round the transverse diameter of the cavities, and in the latter they are circular around their vertical axes. The action of the ventricular muscles must be to approximate the walls of the cavities they enclose, and as their fixed point is above at the fixed base of the heart, they must also shorten these chambers and urge their con- tents towards that point ; and the mammillary muscles having disposed the auricular valves, so as to close the auricular openings, the blood is necessarily propelled into the two great arteries by the synchronous contraction of these muscles ; the light ventricle, having to propel the blood through the pulmonary circulation only, requires less muscular energy and structure than the left, which has to influence the circula- tion through the entire system ; and as both ventricles expel their contents superiorly, they require more muscular power in their centre and base than at the apex ; for the effects of the systole must be, first to close this point, and then propel the blood from it to the centre and base of the cavity, and where, of course, a greater exertion is required to propel it into the arteries; this accounts for the thinness of the K. 130 DUBLIN DISSECTOR. walls at the apex contrasted with the centre and base ; the most fleshy part in the left ventricle is about its middle, and in the right nearer to its base. The changes in the cavities of the heart, and the actions of the car- diac muscles during life, have been observed to occur in the following order : first, the two auricles become distended with blood from the six great veins as well as from the cardiac ; this state (diastole) is fol- lowed by their rapid synchronous contraction, or systole, this is ac- companied by the enlargement, or diastole, of the two ventricles, and this is succeeded by their synchronous contraction, or systole, whereby the blood is propelled into the two great arteries ; then a rest or pause ensues, during which the auricles are again gradually filled from the veins, and the same train of actions follows. The auricular diastole commences during the systole of the ventricles, and is completed du- ring the pause or rest, in a longer or shorter time, according as the venous circulation is slow or rapid : the contractions of the auricles ap- pear rather feeble, and are rapidly followed by the systole of the ven- tricles, or, as it is termed, the systole of the heart. The diastole of the ventricles presents two stages, the first occurs suddenly after their systole, in it the heart returns to its former state, as it were, of rest, and the apex retires backwards and downwards ; the second stage is also rapid, and attended with a sudden and general expansion ; the parietes feel smooth, soft, and flaccid : the first stage is owing, most probably, to the elasticity of the muscular tissue, the fibres of which must have been more or less under compression during the systole ; the second stage depends on the systole of the auricles pouring in the blood, which, in the first stage, only flowed in a passive manner ; many, however, incline to the opinion, that the diastole of the ven- tricles is not a mere passive or elastic yielding, but a real active dila- tation, whereby the blood is drawn in to fill the vacuum, as well as impelled by the contraction of the auricles. In the systole the sur- face of the ventricles is rugged and firm, and the superficial veins dis- tended, the cavities contract in eveiy direction, the vertical and trans- verse axes are diminished, and the apex describes a spiral movement from right to left, and from behind forwards, so as to strike against the fifth and sixth ribs on the left side ; the whole heart appears tilted a little forwards, but most probably the apex only is moved in this di- rection in any sensible manner. That the apex should thus advance to the wall of the thorax during the systole, that is, during the con- traction and shortening of the ventricles, is contrary to what, from a priori reasoning, might be expected, and is, most probably, owing to the peculiar spiral arrangement of the muscular fibres, their greater length and quantity in front, their fixed attachment above to the auricular tendinous zones, their arched or looped course, and the ter- minations of several in the carneae columnar, in the septum, and hi the parietes ; this phenomenon, however, has also been attributed to other causes, namely, first, to the curvatures of the aorta and pulmonary artery : when the ventricles urge the blood into these arteries, it has been supposed that an effort is made to bring the heart and these IM KI.IX 1>I"^KOTOR. 131 curved tubes into one straight line, but the vessels being fixed, and the apex of the heart mow-able, it rotates upwards and forwards in an arc of a circle, and therefore approaches the ribs : secondly, to the position of the auricles, especially of the left, above and behind the ventricles : both auricles being distended at the moment of the ventri- cular systole, it has been maintained by some, must push forward the heart, and the apex in particular: and thirdly, this last agency has been supposed to be increased by the reflux of blood from the conical spaces enclosed between the tricuspicl and mitral valves, meeting that which is flowing in from the large veins, and thus causing such a sud- den distention of the auricles as may account for the protrusion of the heart ; but none of these latter explanations will stand the test of minute examination, and we are therefore disposed to infer, that this change in position of the heart's apex rather depends on the arrange- ment of the muscular fibres as stated above. The actions of the heart during life are accompanied by two distinct sounds, audible with the stethoscope ; the first is dull and prolonged ; the second follows this rapidly, is sharp, clear, and quick, and is suc- ceeded by a pause, after which the same sounds are again heard. The first sound is synchronous with the impulse of the heart against the ribs, or with the ventricular systole, and with the arterial pulse near the heart ; the second sound is synchronous with the first stage of the ventricular diastole ; the two sounds therefore correspond to one arte- rial pulsation. Various explanations have been offered, to account for these phenomena, such as the "bruit musculaire" attending the muscular contraction, particularly of the ventricles ; the impulse of the latter against the chest in the first instance, and afterwards against the thoracic viscera ; the propulsion of the blood through the auriculo- ventrictilar openings and the falling back of their valves ; the rushing of the fluid over the internal rough surface of the ventricles; the sud- den meeting of the auriculo-ventricular valves, by the action of the papillary muscles; the striking of the walls of the contracted ven- tricles against each other ; the rushing of the blood towards and through the narrow arterial mouths, against the semilunar valves ; and lastly, the arterial regurgitat ion of the blood against these valves when thrown across these openings. The limits of a work so purely practi- cal as the present do not permit the discussion of these hypotheses, many of them ingenious ; I shall, therefore, only observe, that in all probability the first sound of the heart, which is heavy and prolonged, and synchronous with its systole, is owing partly to the " bruit mus- ciilt KLIN DISSECTOR. 135 In most quadrupeds it is very strong and elastic, and presents a good example of the yellow elastic tissue. The cervical aponeurosis is not an independent aponeurosis, but only an elliptical portion of the ten- dons of the trape/.ius on each side of the mesial line ; it extends from the lit'tli cervical to the fifth dorsal vertebra, narrow at each extre- mity, and broad in the centre between the superior angles of the two scapula; the fibres are transverse, and continuous with the fibres of the t rape/his on each side ; it gives strength to these, and binds down the subjacent muscles. The lumbar aponeurosis, or fascia, is of great strength in the human subject; like the cervical it is not anin- dejK'iideiit structure, but a common tendon to several muscles, both of the back and of the abdomen ; it is also somewhat oval, attached by its inferior extremity to the spinous processes of the sacrum, and by its superior to those of the inferior dorsal vertebrae and to the two last ribs; on either side it is connected to the crest of the ilium, and to the abdominal muscles, particularly to the transversalis, also to the latissi mns dorsi and serratus posticns inferior ; its internal surface is attached along the median line to the spines of the lumbar vertebrae, and on either side to the transverse processes. In the course of the dissec- tion of the lumbar muscles, this fascia will be found to consist of three lamina 1 , the first, or posterior, that which is seen at present, is very strong and deeply indented in the middle line, from being attached to the spines of the lower dorsal and to those of all the lumbar vertebras and sacrum ; it gives attachment to the latissimus dorsi, serratus pos- ticus inferior, obliquus interims, and transversalis abdominis muscles. The second or middle layer is attached to the tips of the transverse processes of the lumbar vertebra?, and lies posterior to the quadratus lumborum muscle ; and the third, or anterior layer, is in front of the quadratus and psoas muscles, and is attached to the roots of the trans- verse processes and to the sides of the bodies of the lumbar vertebrae. This fascia gives great support to the loins, where the skeleton is com- paratively weak ; like the ligamentum nuchae it supports the trunk in flexion, it also assists in maintaining it in equilibria in lateral motion, and it also serves to give attachment to several muscles, which again, in their turn, serve to keep it in a state of tension ; this great tendinous expansion, together with that derived from the abdominal muscles in front, forms a sort of circular aponeurotic investment for this division of the trunk. The three lamina; of the lumbar fascia are regarded by many as the three tendinous layers of origin of the transversus abdomi- nis muscle ; the posterior layer (the true fascia lumborum) being the strongest, the anterior the weakest ; the posterior and middle laminae form one great aponeurotic sheath to enclose the erector muscles of the spine ; while the middle and anterior form another, which encloses the quadratus lumborum muscle ; the anterior lamina is also continued on the diaphragm, and forms the external ligamentum arcuatum ; these points cannot be fully examined until the abdomen has been opened. The muscles of the back are many of them indistinct, and vary very much in different subjects, both in their appearance and in their exact 136 DIBLIX WSSKCTOII. ' The muscles on the posterior part of the trunk; cm the left side the superficial layer has been removed. 1. The trapczius muscle. 2. The Jatissimus dorsi muscle. IK HI. IN 1HSSKCTOR. 137 attachments to any certain number of vertebrae ; the student is not to expect, therefore, to find each muscle in this region to correspond ac- curately with the description that is given, some being attached to a greater, others to a lesser number of processes than is stated. The muscles of the back are symmetrical on each side, and are arranged in four successive layers, each nearly covering the other between the in- teguments and the bones. These several laminae differ in structure, form, and use; the first and second are broad fleshy expansions, the former rather triangular, the latter quadrangular, and (with the exception of the serrati) chiefly designed to move the shoulder in dif- ferent directions. The third and fourth layers, not so distinctly sepa- rable, are principally elongated slips of muscular fibres, with numerous tendons, for the more convenient attachment to the projecting points of the vertebrae and of the occipital bone, for the purpose of securing the head upon the column, and of erecting and strengthening the latter, as well as for executing slight motions between its several segments, also for moving the head upon the atlas, and rotating both on the dentatns. The muscles of the first layer are two in number, viz., the trapezius and the latissimus dorsi. TKAPEZIUS, broad, triangular, the base along the spine, the apex at the shoulder, thin above and below, thick in the centre ; arises by a thin aponeurosis from the internal third of the superior transverse ridge of the occipital bone, from the ligamentum nuchae, and from the spinous processes of the last cervical, and of all the dorsal vertebrae ; the su- perior fibres descend obliquely outwards and forwards ; the middle pass transversely, the inferior ascend obliquely outwards ; all converge towards the shoulder, and are inserted into the posterior border of the external third of the clavicle, and of the acromion process, also into the upper edge of the spine of the scapula. Use, to raise and draw backwards the shoulder ; the inferior fibres, which end in a triangular- shaped tendon, which glides over the triangular smooth surface at the commencement of the spine, may draw down the base of the scapula, and thus, by rotating this bone, will elevate the acromion process, and assist the remainder of the muscle in raising the shoulder ; the trape- zius may also incline the head backwards and to one side. This muscle is only covered by the skin and a fine closely adhering cellular tissue ; its origin in many points is continuous with that of its fellow, and both are so thin and adherent to the integuments, that without caution in the dissection they may be raised with the latter ; it covers the splenii, complexi, serratus superior, levator scapulae, supra-spinatus, a small 3. The rhomboideus minor. 4. The rhpmboideus major. 5. The levator anguli scapulse. 6. The serratus posticus inferior. 7. 7. The splenius muscle. 8.. Portion of the sacro-lumbalis muscle. 9. Portion of the longissimus dorsi muscle. 10. Part of the complexus muscle. 11. Part of the sterno-mastoid. 12. The deltoid. 13. The supra-spinatus. 14. The infra-spinatus. 15. The teres minor. 16. The tores major. 17. Part of the serratus magnus. 18. Posterior portion of the ex- ternal oblique muscle. 19. Part of the internal oblique. 20. 20. The glutaeus medius. 21. The glutteus maximus. 22. The pyritbrinis muscle. 23. The su- perior gemellus. 24. The interior gemellus. 25. Portion of the obturator internus. 138 DUBLIN DISSECTOR. portion of the infra-spinatus, and of the latissimus dorsi, also the rhomboid and deeper muscles ; its anterior fibres are parallel to the sterno-mastoid, in contact with it above, but separated below, by fat, vessels and nerves ; in some subjects a band of fleshy fibres unites these muscles above the clavicle. The spinal accessory nerve is partly distributed to this muscle, whereby it is associated with the muscles of inspiration, wliich it can assist by raising and fixing the bones of the shoulders. LATISSIMUS DORSI is very broad, and also triangular, the superior external angle being much elongated ; it covers the greater part of the lumbar and dorsal regions, and extends from these to the inner side of the arm ; arises from the six inferior dorsal spines, and by the lumbar fascia from all the lumbar spines and supra-spinal ligament ; also from the back of the sacrum, from the posterior third of the crest of the ilium, and by distinct fleshy slips from the three or four last ribs near their anterior extremity ; the iliac and lumbar fibres ascend obliquely outwards ; the dorsal, wliich are much weaker, pass trans- versely ; and the costal are nearly vertical ; all converge towards the inferior angle of the scapula, over which they glide, and from which they often derive an additional fasciculus of fleshy fibres ; thence the muscle continues to ascend obliquely outwards over the teres major, and near the inside of the arm it twists beneath this muscle to its fore- part, ends in a flat broad tendon, which is closely connected to that of the teres, and is inserted into the concave surface and into the inner or posterior edge of the bicipital groove, anterior and superior to that tendon ; a small bursa is usually found between these tendons in this situation. Use, to depress the shoulder and arm, to draw the arm backwards and inwards, to rotate the humerus inwards, so as to turn the palm of the hand backwards, also to depress the ribs, as in expi- ration ; but if the upper extremity be raised and fixed, this muscle may elevate the ribs, and so assist in inspiration, as well as in raising the whole body, as in climbing. The dorsal portion of the latissimus dorsi is covered by the trape- zius ; the remainder of this muscle is superficial, its origin is superior to the glutseus maximus, its anterior edge is connected to the abdo- minal muscles, the inferior fasciculi of the external oblique indigitate with its costal origins ; it covers the serratus inferior, the lumbar muscles, and the angle of the scapula ; its humeral end forms the pos- terior fold of the axilla ; a fasciculus of fleshy fibres sometimes passes across the floor of this region, and connects the latissimus to the great pectoral muscle ; between the angle of the scapula and the humerus this muscle has a twisted appearance,, the lumbar and costal fibres become anterior, and are inserted into the upper part of the tendon, while the superior or dorsal become posterior, and are inserted into its inferior edge; the axillary vessels and nerves lie on this tendon at its insertion, and the bicipital groove is lined by aponeurotic fibres derived from it, and from the tendon of the great pectoral, which are thus united to each other, although previous to this they nnu.i.v PISSKCTOR. 139 raU'd I iy tin- brachial vessels and nerves, and by the coraco- brachialis and biceps muscles; from the upper edge of the tendon a band ascends to the lesser tuberosity of the humerus, and from its lower border an expansion to join the brachial aponeurosis. Divide the trapezius and latissimus longitudinally between the spine and the scapula, reflect one portion towards the vertebra?, the other towards the side, and the second layer of the dorsal muscles will be exposed. (In dissecting off the latissimus take care not to injure the serratus inferior, which is very thin and adheres closely to it). The second layer of muscles consists of the rhomboid, levator an- guli scapula?, serratus inferior and superior, and the splenii ; a con- siderable portion of each of these is now seen, although they partly conceal each other. RIIOMBOIDEUS is the most superficial of this layer ; broad, thin, thicker below than above ; it is divided into a superior or minor por- tion, and an inferior or major ; the minor arises from the lower part of the ligament um nucha?, and from the two last cervical spinous pro- cesses ; the fibres run parallel outwards and a little downwards, and Fig. 26. * A part of second and third layers of muscles of the back. 1. The occipital hone. _'. the mastoid process of temporal bone. 3. The splenius. 4. The complcxus. 5. The levator anjruli scapula?. 6. The scrratus posticus supe- rior. 7. The sacro-lumbalis. 8. The longissimus dorsi. 9. The spinalis dorsi. 10. Portion of the external intercostal muscles. 140 DUBLIN DISSECTOR. are inserted into the base of the scapula, opposite to and above the spine. The major arises from the four or five superior dorsal spines ; the fibres pass outwards and downwards, parallel to the former, and are inserted into a thin tendinous arch which extends along the base of the scapula from its spine to the inferior angle, also into the latter by a strong tendon with which the arch is continuous ; beneath the latter, anastomosing vessels pass between the posterior and subscapular arteries. Use, to draw the shoulder backwards and upwards ; the inferior fibres also can, by pulling back the inferior angle, rotate the scapula so as to depress the acromion process, thereby assisting the levator anguli and the pectoralis minor muscles. The rhomboid mus- cles are covered by the trapezius and latissimus, but a portion of the major between these muscles is subcutaneous ; then* origin is intimate- ly connected with the trapezius, and their insertion is between those of the serratus magnus, and the supra and infra-spinati muscles ; they conceal part of the splenii and serrati postici muscles. LEVATOR ANGULI SCAPULAE, long and flat, placed at the upper and posterior part of the side of the neck, arises by four or five distinct and separate tendons from the posterior tubercles of the transverse processes of the four or five superior cervical vertebrae ; these soon terminate in a fleshy belly, which descends obliquely outwards and backwards, and is inserted into the base of the scapula, between the spine and superior angle ; its use is to elevate the whole scapula, if assisted by the trapezius, or to elevate the superior angle alone, and to rotate the scapula so as to depress the acromion, thus cooperating with the lesser pectoral muscle ; it can also bend the head a little back- wards, and to its own side. It is covered by the trapezius ; a small portion may be seen superiorly between this and the sterno-mastoid muscle ; the tendinous origins have those of the splenius colli behind them, and of the scaleni and rectus capitis anticus major before them. Divide and reflect the rhomboid muscles ; beneath these a quantity of loose cellular membrane is placed, between them and the serratus magnus, to the posterior view of which muscle the student should now attend ; he may, therefore, again peruse the account given of that muscle. (See page 80.) SERRATUS POSTICUS SUPERIOR, placed on the superior posterior part of the thorax, somewhat square, arises by a thin aponeurosis from the ligamentum nuchse, and from two or three dorsal spines, forms a thin fleshy belly, which ends in three fleshy slips, which are inserted into the upper borders of the second, third, and fourth ribs, external to their angles. Use, to expand the thorax by elevating the ribs and drawing them outwards. This muscle is covered by the trapezius and rhomboid ; it lies on the splenius and the deep layer of muscles ; an aponeurosis is continued from it to the inferior ser- ratus. SERRATUS POSTICUS INFERIOR, at the lower part of the dorsal, and upper part of the lumbar regions, is broader and thinner than the last, arises by a thin tendinous expansion, which is connected through DUBLIN DISSECTOR. 141 the lumbar fascia to the two last dorsal and two upper lumbar spines ; it forms a thin fleshy expansion, which divides into three or four fas- ciculi, which are inserted into the lower edges of the four inferior ribs anterior to their angles ; the highest digitation is the largest, and the lowest extends as far forwards as the tip of the last rib. Use, by de- pressing the ribs it assists the abdominal muscles in expiration ; also, by fixing the lower ribs it increases the power of the diaphragm, and by aiding this muscle in enlarging the thorax it assists in inspiration ; the two serrati also, by making tense the aponeurosis which connects them to each other, compress and support the deep muscles in this region. This aponeurosis may be named vertebral or dorsal, in con- tradistinction to the cervical and lumbar, is broad and quadrilateral, attached internally to the dorsal spines, externally to the angles of the ribs, below to the edge of the serratus inferior, and above to that of the serratus superior, beneath which also it extends to cover the splenii muscles ; the fibres are mostly transverse ; though thin, and nearly transparent, it is tense and strong. The serratus posticus lies under the middle of the latissimus dorsi, to whose tendon it adheres inti- mately, but can be separated from it by cautious dissection ; its at- tachment to the ribs is behind those of the external oblique and latis- simus dorsi muscles. Reflect from their origin the serrati ; beneath the superior, we shall see the following muscle. SPLEXIUS is long and fat, fleshy and tendinous, lying beneath the trapezius, and extending in an oblique direction from below, upwards, forwards, and outwards ; it is divided about its centre into two por- tions, the inferior, or splenius colli, and the superior or splenius ca- pitis. The splenius colli arises from the spines of the third, fourth, fifth, and sixth dorsal, ascends obliquely outwards, and is inserted by distinct tendons into the transverse processes of the three or four su- perior cervical vertebra? behind the origins of the levator scapula?. Use, to bend the neck backwards, and to one side. Splenius capitis is larger than the last, superior and internal to which it lies ; it arises from the spinous processes of the two superior dorsal and three in- ferior cervical vertebrae, and from the ligamentum nuchae ; it ascends a little obliquely outwards, and, becoming larger, is inserted into the back part of the mastoid process, overlapped by the sterno-mastoid, also into the occipital bone, below its superior transverse ridge. Use, to bend back the head, and when one only acts to turn the head to that side ; thus cooperating with the sterno-mastoid of the opposite side. The splenii are covered below by the rhomboids and serratus superior, higher up by the levator anguli scapula?, and still higher by the sterno-mastoid muscles ; strictly speaking, they are but one mus- cle. The splenii capitis muscles diverge superiorly, and the complexi, which converge, appear between them. Detach the splenii from the spinous processes, and divide the fascia lumborum, and the next layer of muscles will appear ; this consists of the sacro-lumbalis, longissi- mus dorsi, and spinalis dorsi, cervicalis descendens, transversalis colli, trachdo-mastoideus, and complexus. 142 * The deep-seated muscles of the back, and posterior region of the neck. 1.1. The mastoid process of the temporal bone. 2. A portion of the occipital bone. 3. 3. The ossa innominata. 4. The os coccygis. 5. The sacro-lumbalis muscle. 6. The longissimus dorsi. 7. The spinalis dorsi. 8. 8. The cervicalis ascendens. 9. 9. The transversalis colli. 10. The trachelo-mastoideus. 11- The complexus. 12. 12. The semi-spinalis colli. 13. The semi-spinalis dorsi. 14. The rectus capi- tis posticus major. 15. The rectus capitis posticus minor. 16. The obliquus ca- pitis inferior. 17. The obliquus capitis superior. 1H III.IN DISSECTOR. 143 SACRO-LUMBALIS, LONGISSIMIS DORSI, and SrixALis DORSI, those three museles are so closely connected inforiorly as to appear but one ma>s of an oval form, narrow at the sacrum, full and prominent in tin' loins, and narrow in the back ; several fibres must be divided in order to separate them from each other ; they fill the hollow between tin- angles, of the ribs and the spinous processes ; the sacro-lumbalis is external, the longissimus dorsi in the middle, and the spinalis dorsi is internal. Sacro-linahaliit is the largest of the three; it arises from the posterior third of the crest of the ilium, from the oblique and trans-- verse processes of the sacrum, from the sacro-iliac ligaments, and from the transverse and oblique processes of the lumbar vertebra ; it as- cends and divides into several long tendons, which are inserted into all the ribs near their angles. Use, to extend the spine, and bend it a little to one side, also to depress the ribs as in expiration. The lon- gissimus dorsi lies internal to the last, and arises, in common with it, from the posterior surface of the sacrum, and from the spinous, transverse and oblique processes of the lumbar vertebrae ; ascending along the vertebral column, it is inserted internally by small tendons into the transverse processes of all the dorsal vertebra;, and externally by fleshy and tendinous slips into all the ribs between their tubercles and angles. Use, to extend, bend to one side, and support the spinal column. AVhen we separate the sacro-lumbalis from the longissimus dorsi, and evert the former, we shall expose five or six small tendinous and fleshy fasciculi, which arise from the superior edge of each rib, and ascend- ing are inserted into the tendons of the sacro-lumbalis ; these are called the musculi accessorii ; they are very irregular hi number, structure, and size. Spinalis dorsi lies between the longissimus dorsi and spine ; it arises from the two superior lumbar, and three inferior dorsal spines ; it ascends close to the spinal column, and is inserted into the nine superior dorsal spines ; its use is similar to the last. These three muscles are covered by, but distinct from, the lumbar fascia, and by the two preceding layers. These muscles in old sub- jects will be often found soft, weak, and pale, and often blended with a soft fatty substance, so as sometimes to resemble a mass of adi- pocere. CERVICALIS DESCEXDEXS, or more properly ASCENDEXS, looks like a continuation of the sacro-lumbalis, internal to which it arises, by four or five tendons, from as many of the superior ribs, between their tubercles and angles; these unite in a small fleshy belly, which ascends obliquely forwards and outwards, and is inserted by three or four tendons into the posterior tubercles of the transverse processes of the fourth, fifth, and sixth cervical vertebrae, between the spleniiis colli and levator scapulae. Use, to extend the neck, and incline or turn it to one side ; it may also assist in inspiration by elevating the ribs. TRAXSVERSALIS COLLI appears as a prolongation of the longissimus dorsi, internal to which it arises by small tendinous and fleshy slips from the transverse processes of five or six superior dorsal vertebrae ; the fibres uniting ascend obliquely outwards and forwards, and are 144 DUBLIN DISSECTOR. inserted by small tendons into the transverse processes of four or five inferior cervical vertebrae, between the cervicalis descendens and the trachelo-mastoideus ; its use is nearly similar to that of the last de- scribed muscle. TRACHELO-MASTOIDEUS, also like a continuation of the longis- simus dorsi, lies internal to the last, and external to the complexus ; it arises by several tendinous bands from the transverse processes of three or four superior dorsal vertebrae, and from as many inferior cer- vical ; ascending a little outward it is inserted into the inner and back part of the mastoid process, beneath the insertion of the splenius. Use, to assist in extending the neck, to bring the head backwards, and to incline and rotate it to one side. This muscle is covered by the sple- nius and transversalis, it lies upon the complexus, the obliqui capitis, and the digastric muscles. COMPLEXUS, thick and strong, arises from the transverse and oblique processes of three or four inferior cervical, and five or six su- perior dorsal vertebrae, internal to the transversalis and trachelo-mas- toideus ; it forms a very thick muscle intersected by many tendinous bands ; it ascends a little inwards, crossing the splenius, and is inserted close to its fellow into the occipital bone, between the two transverse ridges. Use, to draw back the head, to fix and support it on the spine, also to rotate it, being, in this action, an antagonist to the splenius, and an auxiliary to the sterno- mastoid of its own side. The complexus is concealed by the trapezius and splenius ; its insertion, which is covered by the former only, can be felt and seen tlirough the integuments ; it lies on the semi-spinalis colli, the deep cervical artery, and the small obliqui and recti muscles ; it is sometimes a di- gastric muscle, having a perfect tendinous intersection. Detach the complexus from the spine, and reflect it towards the occiput, and evert towards the ribs the other muscles of this layer, AVC shall thus expose the fourth layer of the dorsal muscles, which consist of the spinalis or semi-spinalis colli, the semi-spinalis dorsi, multifidus spinae, inter- spinales, inter-transversales, and immediately below the occiput, the recti postici, major and minor, and obliqui capitis, superior and in- ferior. SPINALIS, or SEMI-SPINALIS COLLI, is one of the largest muscles in this region; it arises from the extremity of the transverse pro- cesses of five or six superior dorsal vertebrae, ascends obliquely in- wards close to the spine, and is inserted by four heads into the spinous processes of the second, third, fourth, and fifth cervical vertebrae. Use, to extend the neck and incline it a little to its own side ; this thick muscle fills up the space between the spinous and transverse processes of the cervical and dorsal vertebrae ; it lies external to the semi-spi- nalis dorsi, is overlapped by the longissimus dorsi inferiorly, the com- plexus superiorly, and the serratus posticus superior hi the middle. SEMI-SPINALIS DORSI is similar to the last muscle in form and attachment ; indeed they appear as one long muscle, which has been thus rather unnecessarily divided into two, each named from the situa - i>issi:rTOR. 1 I."- tion of its principal portion; arises by five or six tendons from the transverse processes of the dorsal vertebra 1 , from the fifth to the eleventh : its (litres ascend obliquely inwards, and are inserted by five or six tendons into the spinous processes of two inferior cervical, and three or four superior dorsal vertebra?. Use, cooperates with the last described muscle, in extending the neck, supporting the trunk, and inclining the spine backwards, and to one side ; it is situated close to the spine above, and internal to the last muscle ; but below, it lies on the outer side of the spinalis dorsi. Mri.TiFinus SPIN^B is close to the vertebrae, between the spinous and transverse processes, and is covered by the two last described muscles ; it consists of a series of small tendinous and fleshy fascicidi ; the first arises from the spine of the dentatus, or second vertebra, and, descending obliquely outwards, is inserted into the transverse pro- cess of the third ; thus the succeeding muscles are attached, run- ning obliquely from vertebra to vertebra between their spinous and transverse processes ; some fasciculi extend over two or three vertebra? ; the hist arises from the spine of the last lumbar vertebra, and is in- serted into the false transverse process of the sacrum. Use, to sup- port the spinal column, extend it, and incline it to one sicle, also to rotate one bone upon the other, as far as their articulating surfaces will admit. INI KK-srixALEs are short muscles, consisting of longitudinal fibres ; their name expresses their situation and attachment ; between the cervical spines they are more distinct, and appear to be in pairs, right and left, as the spinous processes here are forked ; some fibres in the neck deserve the name of supra-spinous muscles, as they pass over these processes, cover and adhere to several of them ; in the back they are very indistinct, almost wanting, and in the loins they are much weaker than in the neck, chiefly consisting of ligamentous fibres, with a few muscular intermixed. Use, to support and extend the spine. IXTER-TRANSVEUSALCS consist of longitudinal fibres attached and situated as their name implies ; between the cervical vertebra? these nuiscles are more strong and distinct, and consist of two planes, an anterior and posterior ; between the lumbar vertebrae they are less distinct ; and still less so, indeed often wanting, between the dorsal. Use, to support the spine on either side, and to bend it laterally. External to these in the back, the levatores costarum muscles are seen, which have been already noticed in the description of the intercostals. Be- tween the occiput and the first and second vertebrae, the following four pair of muscles are situated. RECTUS CAPITIS POSTICUS MAJOR, triangular; arises narrow from the spinous process of the second vertebra ; ascends outwards, an< I is inserted broad into the inferior transverse ridge of the occipital bone. Use, to extend the head, or draw it backwards, so as to turn the face upwards, also to rotate it and the atlas on the dentatus, co- operating with the splenius of the same side; this muscle is situated obliquely between the occiput and the second vertebra ; it is covered 146 DUBLIN DISSECTOR. by the complextis ; its insertion is overlapped by that of the superior oblique. RECTUS CAPITIS POSTICUS MINOR, also triangular, arises narrow from the posterior part of the atlas ; passes upwards, outwards, and backwards, and is inserted broad into the occipital bone, behind the foramen magnum. Use, to assist the former in drawing back the head, and steadying it on the spine ; this pair is partly covered by the last muscles ; a portion of them, however, is seen between these ; both the recti resemble the continuation of the inter-spinous muscles, but are much more oblique, so that the name recti is by no means accu- rate. OBLIQUUS CAPITIS INFERIOR is the strongest of these small mus- cles ; it arises inferior and external to the posterior rectus, and su- perior to the spinalis colli, from the spinous process of the second vertebra, ascends obliquely forwards and outwards, and is inserted into the extremity of the transverse process of the atlas. Use, to ro- tate the head and atlas on the second vertebra, cooperating with the splenius of the same side, and the sterno-mastoid of the opposite side ; this muscle is covered by the complexus, trachelo-mastoideus, and trapezius, if conceals the lamina of the second vertebra, and the ver- tebral artery. OBLIQUUS CAPITIS SUPERIOR, smaller than the last, above the in- sertion of which it arises, narrow, from the upper part of the trans- verse process of the atlas, ascends obliquely inwards and backwards, overlapping the rectus, and is inserted broad into the occipital bone, between its transverse ridges, just behind the mastoid process, and above the rectus major. Use, to bend the head to one side, and to draw it a little backwards ; it cannot have any rotatory power, as there is no rotation between the occipital condyles and the atlas. These four pair of muscles are but higher developments of segments of the long spinal muscles which have been traced inferiorly ; the recti are analogous to the inter-spinous, the obliqui to the transverse spi- nous, for the mastoid process of the temporal, and the transverse ridge and tubercle of the occipital bones correspond to the projections of the spinal column. The recti and obliqui are separated from the com- plexi, by a strong aponeurosis, and much cellular tissue, which allows of the free motion of the atlas round the pivot of the second vertebra ; these small muscles on each side bound a triangular space nearly equi- lateral ; the recti in the middle line form the common base, the ex- tremity of the transverse process of the atlas is the apex of each, while the superior and inferior oblique muscles form the sides ; this space encloses a quantity of adeps and tough cellular tissue, deeply imbedded in which we may find the vertebral artery, a plexus of veins, some of which join the vertebral veins, others pierce the atlanto-occipital liga- ment, or pass through the posterior condyloid holes to open into the lateral sinus ; in this region also is the posterior division of the sub- occipital nerve, dividing into its branches to supply this group of small muscles ; when all these parts have been removed, we shall ex- DIHI.IX DISSKCTOR. 147 pose the semicircular rim of the atlas, the lamina of the dentatus, and tlic posterior atlanto-oceipital and axoid ligaments. The muscles of the back are found very unequally developed in dif- ferent subjects; in the young, active, and robust, who have died of acute disease, they will be found red, strong, and distinct, but in those who have been enfeebled and emaciated by long illness, in the para- lytic, and the bedridden, also in the very old, especially of the female sex, they often present, particularly in the lumbar and dorsal regions, a pale, weak, soft, yellowish appearance, with but little remains of the true muscular structure, and are not unlike the degenerated fatty heart occasionally found in the old and anasarcous, or the muscles adjacent to a scrofulous joint. This abnormal condition, so often met with in the aged in these particular muscles, may be partly the effect of want of exercise, and appears in conformity with the general stiffening of the spinal column, and shrivelling of the inter-vertebral ligaments, whereas, the motions of the head and neck continuing to the latest period of life, the muscles in the cervical region preserve their normal structure. In the dissection of the muscles of the back but few vessels or nerves of size or note are met with ; the arteries which supply these muscles are branches of the occipital and deep cervical superiorly ; the posterior branches of the intercostals in the middle, and of the lumbar arteries below. The veins accompany the arteries and join the nearest venous trunks. The nerves are the small posterior branches of the cervical, dorsal, and lumbar spinal nerves. 148 miHT/ix DISSECTOH. CHAPTER V. DISSECTION OF THE UPPER EXTREMITY. THE upper extremity is connected to the trunk by the stern o-cla- vicular ligaments, and by ten muscles, of which one is connected to the clavicle (subclavius), two to the humerus (pectoralis major and latissimus dorsi), and eight to the scapula, viz., trapezius, levator anguli scapulas, omohyoid, rhomboid major and minor, serratus mag- nus, pectoralis minor, and latissimus dorsi ; this last is also inserted into the humerus ; all these muscles have been already examined ; these the student may divide, then separate the extremity from the trunk, and place a block under the axilla ; the dissection of the arm, however, may also be performed while it remains connected to the body. The muscles of the upper extremity are classed into those of the shoulder and arm, forearm, and hand. SECTION I. DISSECTION OF THE MUSCLES OF THE SHOULDER AXD ARM. DISSECT off the integument from the shoulder and arm, as low as the bend of the elbow. The subcutaneous tissue is cellular and adi- pose, but very variable as to quantity and consistence, and does not deserve the name of superficial fascia ; beneath this, in the dissection of the scapula and brachial regions, we meet with different aponeuroses, which are more or less continuous with each other, but differ in struc- ture in different situations. 1. The SUPRA-SPINOUS FASCIA ; this is strong and tense, adheres to the borders of the fossa, and covers the muscle of that name, and is gradually lost on its tendon beneath the acromion process. 2. The INFRA-SPINOUS FASCIA is also very strong, is attached to the borders of the corresponding fossa, binds down the muscle within, and sends in septa between it and the teres minor and major muscles ; at the posterior edge of the deltoid it divides into two laminae, one, thin and delicate, passes over this muscle and joins the brachial aponeurosis, the other continues on the infra-spinatus and teres minor tendons, passes loosely over the joint, and is lost on the biceps and coraco- brachialis muscles. 149 The Srr.x AIM I.AI; FAM IA, weak and thin, but distinct, cover- the muscle of that name, and divides it into fasciculi by septa which pass in deep to adhere to projecting ridges on the bone. The BRA* IIIAL APONKIKOSIS invests the arm down to the elbow, over which it is partially continued into the fascia of the forearm ; it i- weak and imperfect in some places, as on the deltoid muscle, in others it is strong and well-marked ; its strength and tension increase as it descends; its fibres are mostly in the circular direction, but many are spiral and vertical : above it is continuous with the fascia cover- ing the pectoral and deltoid muscles, below the former it receives an addition from the fascia of the axilla, and from the posterior border of the latter, and from the infra-spinous fascia a considerable increase ; still lower down, tibres join it from the insertions of the deltoid, pec- toral, and latissimus dorsi ; these last-named muscles are enabled thereby to act slightly on it, and increase its tension, as it has no distinct tensor muscle like the fascia of the thigh ; about the middle of the arm the brachial aponeurosis adheres to the lateral ridges of the hu- merus by two septa named internal and external intermuscular liga- /H fiits, the fibres of these are oblique and vertical. The external com- mences at the lower part of the outer lip of the bicipital groove, receives a strong slip from the deltoid insertion, and descends to the outer condyle, is stronger and thicker above than below, it separates the triceps from the brachiaeus anticus muscle, and both receive fibres from it ; the musculo-spiral nerve and artery perforate it about its lower third, and then descend anterior to it. The internal is more distinct than the external, of a triangular form, the apex above thin, the base towards the inner condyle thick and strong ; it commences from the inner lip of the bicipital groove, below the teres major tendon, soon becomes continuous with that of the coraco-brachial, crossing its fibres obliquely, adheres to the internal ridge of the humerus, and is inserted broad into the inner condyle ; this ligament also separates the bnichut'us and triceps muscles, and affords attachment to fibres of each ; the ulnar nerve is anterior to it above, but perforates it, and lies be- hind it below; in addition to these two great septa between the flexors and extensors, this fascia also sends in thin processes to enclose the individual muscles, and to encircle the brachial vessels and nerves in an imperfect sheath ; inferiorly it is prolonged into the fascia of the forearm, which we shall examine afterwards. The brachial fascia serves to confine the several muscles in then- situations with such a degree of tension as not to restrain their actions ; it also augments the surface of their attachment, and compresses them together so as to preserve the form and symmetry of the limb ; it also protects the ves- >el> and ni Between the integuments and fascia of the arm we notice two cu- taneous veins, the cephalic on the outer, and the basilic on the inner HIS-I ( TOR. L58 SIK-M Arri..u:is is situated on the inner side of the scapula, op- posite to the three 1 last described muscles, broad and triangular, the base behind, Hit- apex before; it arises from all tin- surface and cir- cumfereiiee of the sub-scapular fossa, also by a few fibres from the long tendon of the triceps ; the lihres run in thick fasciculi upwards and forwards, and all converge towards the neck of the scapula, over which they glide, in a sort of pulley, beneath the coracoid process, and the muscles which are inserted into it ; they end in a tendon which is in- timately united to the capsular ligament, and inserted into the internal or small tubercle of the luunerus ; this muscle is covered by the sca- Fig. 29.* * The ndMcapnlar muscle and muscles of the arm. 1. The coracoid process of the scapula. _'. The acromion process. -',. The superior costa of the scapula. 4. The su|ira-spinatus muscle. 5. The subscapular muscle. 6. The inferior border of the tercs minor muscle. 7. The tores major muscle. 8. Portion of the Ijitissimus dorsi muscle. 9. The coraco-brachialis muscle. 10. The short head of the triceps muscle. 11. The long head of the triceps. 12. The tendon of the biceps inserted into the tubercle of the radius. 13. The long portion of the triceps muscle. 14. Portion of the outer bead of the triceps. 15. Internal or short portion of the .triceps. 1C. The brachialis anticus muscle. 17. Portion of the pectoralis major muscle. 154 DUBLIN DISSECTOR. pula and the muscles of the shoulder ; its inferior edge is in contact with the teres major; its internal surface, which forms part of the axilla, is connected to the serratus magnus, and to the axillary ves- sels and nerves, by loose cellular membrane ; a large bursa, very often communicating with the joint, lies between its tendon and the neck of the scapula, beneath the coracoid process ; another smaller bursa is sometimes situated lower down, between the tendon and the capsular ligament ; the inter-muscular septa often separate this muscle into three portions which thus correspond to the three muscles on the other aspects of the joint. Use, this, which is the strongest of these cap- sular muscles, strengthens the inner side of the articulation, and guards against dislocation when the elbow is suddenly drawn back- wards and outwards. This muscle can depress and adduct the arm, draw it backwards, and rotate it inwards, so as to turn the palm of the hand backwards, thus it antagonizes the infra-spinatus and teres minor muscles. The deltoid and the four capsular muscles, which have been just described, are of great use to the shoulder articulation ; the head of the humerus is so large, the glenoid cavity so superficial, and the cap- sular ligament so loose and long, that, but for these muscles, the bones could not remain in apposition ; hence, in cases of paralysis of the muscles of this region, the joint becomes elongated and flattened, and a partial dislocation exists ; in the dissected limb also, if we divide all the muscles surrounding the capsule, and leave the latter uninjured, the bones will no longer be in contact ; these muscles, therefore, serve to strengthen the capsule, to keep the head of the humerus pressed against the glenoid cavity, and thus to counteract that tendency to dislocate the head of the bone, which the larger muscles of the limb frequently have, in consequence of their insertion being at such a dis- tance from the centre of the joint, added to the anatomical imperfec- tions in the latter already alluded to ; which imperfections, however, are much counterbalanced by the great mobility which the joint enjoys in consequence of this formation, by the numerous opposing muscles which serve to protect the articulation, and by the rotatory motion of which the scapula is allowed to partake. TERES MAJOR, long and flat, arises from a rough, flat surface on the inferior angle of the scapula, below the infra-spinatus, and from the fascia which separates it from the adjacent parts ; it forms a thick fleshy belly, which ascends forwards and outwards to the inner side of the arm, and ends in a broad, thin tendon, which is at first closely connected to the back of the tendon of the latissimus dorsi ; but near the humerus a small bursa intervenes, and is inserted into the inner or posterior edge of the bicipital groove, behind the tendon of the la- tissimus, and in general, but not always, extending lower down than it. Use, to rotate the humerus inwards, to adduct and draw it down- wards and backwards ; also to draw forward the inferior angle of the scapula ; whereby it not only assists the capsular muscles in retaining these two bones in apposition, but it also keeps the glenoid cavity op- IH'IU.IN KlSsI-X'TOR. 155 ].n>rd {o the head of the- hnmerus. Tlie origin of this muscle is su- perficial, but the latissimus dorsi generally overlaps it, and then, turn- ing round its lower edge, heroines anterior to it ; it is here connected to the infra-spinatus and teres minor ; from tlie latter the long Iiead ot'thr triceps afterwards separates it ; it passes anterior to this muscle, and assists the latissimus dorsi in forming the posterior fold of the axilla. Tlie tour muscles of the arm are the coraco-brachialis, biceps, and brachheus anticus in front, and the triceps behind; the latter is the extensor of the elbow joint, and is analogous to the rectus and vasti on the forepart of the femur ; the biceps and brachiams, aided by the muscles of the forearm, wlu'ch arise from the inner condyle, are flexors of this joint ; the flexors predominate over the extensors, the con- trary is the case in the knee joint ; this arrangement is conformable to the destined function of each limb ; the upper extremity being for prehension and attraction towards the head and trunk, the flexors prevail, whereas the lower being for support in standing and in pro- iiiv^sioii, the extensors require and accordingly possess greater power. CORACO-BRACHIALIS arises tendinous and fleshy from the point of the coracoid process, and from the tendon of the short head of the bi- ceps ; it descends obliquely forwards, and is inserted, chiefly tendi- nous, into the internal side of the humerus, a little below the middle, and into the ridge leading to the internal condyle, by an aponeurosis, which is connected to the internal inter-muscular ligament, and is thereby joined to the fascia of the ann. Use, to adduct, raise, and draw for- wards the arm ; also to rotate it outwards. The origin of this muscle cannot be separated from the short head of the biceps, but as it de- scends, it lies behind, and to the inner side of that muscle ; it is covered above by the deltoid and pectoral ; a small portion of it below is super- ficial, and is seen between the biceps and triceps ; its insertion is just below that of the teres major, and separates the brachiaeus anticus and posticus ; the coraco-brachialis passes over the tendon of the subsca- pular, latissimus, and teres muscles ; the brachial artery and median nerve at first lie to its inner side, but pass superficial to its insertion ; the belly of this muscle is generally, but not always, perforated by the external, or musculo-cutaneous, or perforans Casserii nerve ; one of the roots of the median nerve also sometimes passes through it. Bit'Ers is situated along the forepart of the humerus, and consists of two portions superiorly, the external or long, the internal or short ; the internal arises tendinous from the coracoid process, between the coraco-brachialis and triangular ligament ; it soon becomes fleshy, de- fends obliquely outwards, and a little above the middle of the hume- rus is united to the external, or long head, which arises by a long tendon, from the upper part of the glenoid ligament of the scapula ; this tendon passes outwards through the joint over the head of the humerus, within the capsular ligament, but external to the synovial membrane ; it then descends into the groove, between the two tubero- sities of this bone, in which groove it is bound down by tendinous lihn-s, continued from the capsular ligament, and from the adjacent 10<) DUBLIN DISSECTOi:. tendons ; the synovial membrane of the joint is reflected on this ten- don at is origin, and is again reflected from it iuferiorly on the parietes of the groove, between the tendons of the great pectoral, latissimus dorsi, and teres major muscles; thus, although the tendon passes through the cavity of the joint, it is, strictly speaking, external to the synovial membrane. About the middle of the humerus these two portions of the biceps unite in a large fleshy belly, winch, descending to within about an inch and a half of the elbow joint, ends in a flat tendon ; this sends off a process from its anterior and outer border, called the semilunar fascia, which passes obliquely inwards to join the general aponeurosis of the forearm, the tendon then sinks below the joint into a triangular hollow between the supinator longus and pronator teres, and is inserted into the back part of the tubercle of the radius ; a bursa intervenes between this tendon and the anterior part of the tubercle, which is covered by cartilage; the semilunar fascia, which arises narrow from the forepart of this tendon, opposite the bend of the elbow, passes upwards and inwards, expanding towards the inter- nal condyle, to which, and to the muscles proceeding from it, some of its fibres are attached ; the remaining become continuous with the aponeurosis of the forearm. Use, to flex the forearm, and make tense its fascia ; also to abduct and raise the arm. When the hand is prone, the first effect of the contraction of the biceps is to roll the radius out- wards, and turn the hand supine, which it does with great power, as the tendon glides round the tubercle ; the long tendon of the biceps, by passing over the head of the humerus, prevents this bone being dis- located upwards and outwards, as otherwise might occur, in conse- quence of a fall, or of a sudden muscular contraction ; the biceps may also assist the coraco-brachialis, in rotating the scapula on the hume- rus, so as to depress the point of the shoulder. The long head of the biceps is concealed by the deltoid, supra-spinatus, and capsular liga- ment ; the short head by the great pectoral and deltoid ; not unfre- qucntly this muscle has another origin from the humerus below its head ; in some a fasciculus unites it to the coraco-brachialis, and in others to the brachiaeus anticus muscle, which lies behind it. The belly is superficial, and lies on the brachialis anticus, so also is the ten- don in its passage over the elbow joint, but as it approaches its inser- tion it lies very deep, and is embraced by the supinator brevis muscle, a bursa often separates it from the tendon of the brachiaeus anticus ; the brachial artery descends along its internal border, and somewhat overlapped by it, in the middle and lower part of the arm. This muscle or its tendon will serve as a guide in the living subject, in case we are required to tie this vessel, but superiorly the coraco-brachialis intervenes ; the semilunar fascia is extended over the brachial artery and nerve, and affords them some, but not a constant protection, in performing venesection in the median basilic vein, which vein is su- perficial to this fascia, but parallel, and often so close to the artery as to expose the latter to some danger in that operation. In dislocation, urni.IX DISSECTOR. Fig. 30.* and in other injuries of the shoulder joint, the long tendon of the bi- ceps is sometimes ruptured. 15i:.V( IIIAI.IS ANTHTS, or EXTEUXUS, improperly called by some IxTEiixrs, arises from the centre of the humerus by two fleshy slips, one on either side of the insertion of the deltoid, from the forepart of the bone down to the oondyles. and on each side as far as the intermus- cnlar ligaments : the fibres descend converging, pass anterior to the elbow joint, adhere to the synovial membrane, and are inserted by a strong tendon into the coronoid process of the ulna, and into a rough surface on this bone beneath that process. Use, to flex the forearm, and in doing so it draws the syno- vial membrane out of the angle of the joint ; it also strengthens this articulation in its extended state, by pressing the ulna against the hu- merus, and supporting the joint in front ; this muscle is covered by the biceps and by the brachial vessels and nerves ; external to the biceps it is superficial ; its external head is the longer, and lies between the deltoid and second head of the triceps ; lower down the external cutaneous nerve and cephalic vein are to its outer border; and on a deeper plane, the musculo-spiral nerve and artery separate it from the supinator longus, and from the extensors of the carpus ; the inter- nal separates the deltoid from the coraco-brachialis; the tendon passes deep into the hollow at the elbow, behind the tendon of the biceps, and is inserted on its internal side ; a fleshy fasciculus often unites this muscle and the biceps about the middle of the arm. TRICEPS EXTEXSOR CCBITI co- vers the back of the humerus, and extends from the scapula to the olecranon ; it consists superiorly of three portions, viz., the middle or long, the second or external, and * A posterior view of the upper arm. 1. The posterior surface of the scapula. 2. The capsular ligament of the shoulder joint. 3. The long or middle head of the triceps muscle. 4. Its external head. 5. Its short or internal head. 6. Com- mon tendon of the triceps muscle inserted into 7. The olecranon process of the ulna. 8. The internal condyle of the humerus. 158 DUBLIN DISSECTOR. the third or internal, or short head, or the brachiseus interims or pos- tiens. The long, or middle head, arises by a flat short tendon, about an inch broad, from the lower part of the neck of the scapula, and from the anterior portion of the inferior costa ; it also adheres to the infe- rior part of the capsule and to the glenoid ligament, somewhat like the biceps above, to which it is nearly opposite ; it soon ends in a large fleshy belly which descends along the back part of the hume- rus ; that surface which is towards the bone continues tendinous for some distance ; about the superior third of the arm it joins the second, or exter- nal head, which arises immediately below the insertion of the teres mi- nor by a narrow, tendinous, and fleshy slip, from a ridge on the outer side of the humerus commencing below the great tuberosity, and leading down to the external condyle, it also arises from the bone behind this ridge, from the intermuscular ligament, and from the external condyle, by a tendon which passes upwards and inwards, and joins the remainder of the muscle ; these inferior fibres are parallel to the anconaBus ; the third, or short head, or brachiceus internus, or posticus, improperly called brachiseus externus, arises narrow on the inside of the humerus, above its centre, commencing tendinous j ust below the insertion of the teres major, and continuing to arise from the ridge which leads to the inter- nal condyle, and from the internal intermuscular ligament; these three portions of the triceps unite above the middle of the arm, and, descending along its posterior part, end in a flat broad tendon, which consists of two laminae, a superficial and a deep ; the former is conti- nued over the flat triangular surface of the olecranon into the fascia on the back part of the forearm ; the latter, which is stronger but narrower, is inserted into the posterior border, but not the point, of the olecra- non process. Use, to extend the forearm on the arm, and by its long portion to carry the arm backwards, and in some cases to adduct it ; it also draws up the synovial membrane from between the olecranon process and the humerus, and thus protects it from pressure in the ex- tended state of the limb. The long head gives support to the inferior part of the capsular ligament of the shoulder, and so tends to protect that joint against dislocation, in that situation where it w r ould be most likely to occur. The sudden contraction of the triceps during life sometimes breaks off the olecranon process, and draws upwards the separated portion ; of course, the individual loses for some time the power of extending the forearm ; the fractured piece, however, is pre- vented being separated to any considerable distance partly by a liga- mentous baud which extends from the coronoid process along its side, and partly by the aponeurosis of the triceps which covers the olecra- non, and which joins the fascia of the forearm, also by the inferior fibres of this muscle, which, being connected to the condyles, and hav- ing to ascend a little to the olecranon, tend to keep down its fractured portion. The first, or long head of the triceps, arises and descends between the two teres muscles ; the second, or outer head, commences DUBLIN DISSKOTOK. 159 !>cli>si; ( TOI;. Ihl many long indented lines, like the marks of folds, crossing each other obliquely: on the forepart of the lingers are many line stria-, placed transversely, or circularly, also longitudinally on the first and middle phalanges, and in regular, spiral, and numerous arched curves on the surface of the last ; beneath these the cellular tissue contains a net- work of bloodvessels and nerves, the seat of the sense of touch : in the palm, the adipose substance is granulated and compact, and both it and the skin are connected by aponeurotic fibres to the subjacent strong palmar fascia ; posteriorly the skin is fine, and the cellular tissue is loose and reticular, and contains a number of large superficial veins, which are arranged in a tortuous arch across the metacarpal bones, the convexity towards the fingers receiving the digital veins ; the superficial veins in the palm are very small, and most of them pass into the deep veins ; from the extremities of the posterior cutaneous arch two principal branches proceed, the cephalic and basilic; the basilic commences by a small branch called salvatella from the side of the little finger, it then ascends along the ulnar side of the forearm, receiving in tin's course small branches from the front and back of the arm, and passing anterior to the internal condyle, it is joined by the median basilic ; it then ascends along the inner side of the arm, passes beneath the fascia, and joins one of the deep brachial veins ; sometimes it continues in a superficial course to the axilla, and joins the axillary vein. The cephalic vein commences by several small branches about the thumb and back of the hand ; it ascends along the radial side of the forearm, passes over the bend of the elbow, is joined by the median cephalic, and then ascends along the outside of the arm to the clavicle. The median vein arises by small branches from the forepart of the wrist, it ascends along the forearm between the cephalic and basilic veins, and near the elbow divides into two or three branches: first, the median basilic, which ascends obliquely over the fascia of the biceps to join the basilic ; second, the median cephalic, which passes ob- liquely upwards and outwards, and joins the cephalic vein ; the third branch of the median, when present, sinks deep, and joins one of the deep veins : the cutaneous veins of the forearm are so variable as to size, number, and situation, that they seldom conform precisely to the description given by any author See Venous System. Several subcutaneous nerves are met with in this dissection. The internal cutaneous nerve and its branches accompany the basilic vein, some j Kissing anterior, others posterior to it, and are distributed to the anterior, internal, and posterior aspects of the limb. The external cutaneous, or musculo-cutaneous, in general lies behind the cephalic vein at the bend of the elbow, its branches afterwards twine around that vessel, and are lost on the anterior, external, and posterior parts of the forearm ; the musculo -spiral nerve also gives off a cutaneous branch above the elbow, which descends on the outer and back part of the limb to the wrist ; over the back of the thumb and hand ramify the dorsal branches of the radial and ulnar nerves, while the 162 DUBLIN DISSECTOR. median and ulnar supply the forepart. The relation between the cu- taneous nerves and veins is liable to great variety. The fascia of the forearm, though semi-transparent, is very strong, particularly on the posterior part ; it consists of tendinous fibres, which run in every direction, but principally in the circular and oblique, connected on either side to the condyles, and to the muscles which are attached to these ; it receives an addition from the biceps before, and from the triceps behind ; as it descends, it invests the limb so closely as to give it a certain form ; it sends septa between the different muscles, which separate them into superficial and deep layers, and which also give attachment to several fibres ; it adheres very closely to the olecranoii and to the ulna its whole length ; and inferiorly it is connected to the annular ligaments of the carpus. It is perforated by numerous holes for vessels and nerves ; there is also a deficiency in it just above the fascia of the biceps, where- by the subcutaneous cellular tissue communicates with the inter- muscular ; the fibres of this semilunar process from the biceps tendon descend obliquely towards the inner condyle, intersecting and uniting with the fibres of the aponeurosis which arises in this region ; by means of this process the biceps muscle can act as tensor of the fascia of the forearm ; it also bounds in front, and confines together the sides of the anticubital fossa, which is a sort of narrow, deep, triangular axilla, bounded internally by the pronator teres, externally by the supinator longus ; the apex is below and external, the base is above and behind, formed by the brachiaeus anticus covering the joint ; into this hollow sink the median nerve, the brachial artery, with its venae comites, and the tendon of the biceps a little twisted, first giving off this fascia from its outer and anterior border. The annular ligaments of the wrist appear formed in part by this fascia, strengthened by proper transverse fibres ; the posterior consists of transverse and oblique fibres attached internally to the lower end of the ulna, and to the back of the pisiform bone ; externally to the lower end of the radius ; it is divided into several channels, or canals, by fibrous septa, which pass forwards between the tendons and are inserted into the radius ; there are six of these channels, and, tracing them from within outwards are, first, for the extensor carpi ulnaris ; second, the exten- sor minimi digiti ; third, the extensor communis ; fourth, the extensor pollicis major ; fifth, the radial extensors of the carpus ; and sixth, for the abductor, and extensor pollicis minor ; all these sheaths are lined by distinct synovial bursae which accompany the tendons some way beyond the borders of the ligament, and which materially facili- tate their motions. The anterior is much stronger and independent of the fascia, though connected to it ; attached externally in a curved manner to the scaphoid and trapezium ; the sheath of the flexor carpi radialis tendon runs through this insertion ; internally, to the unciform and pisiform bones, also to the tendon of the flexor carpi ulnaris ; the ulnar nerve separates these osseous attachments ; the fibres are trans- Dl'KUX DISSKCTOK. 1 i't'3 \vr>c and decussating, very strong, and almost as, firm as cartilage; the fascia of the 1'oivarm is attached to it above, that of the palm below, the palmaris tendon in front, the origin of the short muscles of the thumb externally, and the palmaris brevis and muscles of the little linger internally; it forms with the forepart of the carpus a complete ring, through which pass the median nerve and nine tendons, vi/. : the four deep and four superficial common flexors, also the long flexor of the thumb ; the flexor radialis cannot be said to pass through it ; the flexor ulnaris, and the ulnar nerve and arterv, are anterior to it. This ring is lined by the great carpal bursa, which is reflected from the posterior surface of the ligament on the forepart of the common fasciculus of the nerve and tendons, then round their ulnar side to their back part, passing more or less between them, and thence to the front of the carpus, on which it extends con- siderably up and down, and prolonged for some way in the palm along the four flexor tendons. The flexor polh'cis has a distinct synovial sheath which passes a considerable distance on this tendon in each di- rection. The carpal bursa is very liable to distention, it then bulges forward in an irregular form, above the ligament ; it often contains a number of firm, small, granular bodies floating in a thin fluid ; the uses of this bursa are obvious. On the back of the hand a very thin aponeurosis exists, continued from the posterior annular ligament ; it consists of delicate transverse fibres Avhich cover the extensor tendons ; a loose elastic cellular tissue separates it from the integuments. Ante- riorly, there is a remarkably strong fascia, the palmar fascia : this is of a triangular form, commences narrow at the annular ligament, from which, and from the tendon of the palmaris longus, it arises ; it then expands over the palm of the hand, and near the fingers divides into four fasciculi, or rather into eight, as each of them is forked and in- serted into either side of the sheaths of the flexor tendons, and into the capsular ligaments of the first phalanges ; transverse bands pass across these diverging fasciculi, and prevent their divarication, and thus fibrous arches are formed under which the flexor tendons and the digi- tal nerves and vessels pass, secure from displacement and from pressure ; several fibres penetrate between the tendons, and join the metacarpal bones and the interosseous muscles ; this fascia is closely connected to the integuments, but loose cellular tissue intervenes between it and the palmar vessels and nerves and the flexor tendons which thus can move easily beneath it ; two strong septa pass from its deep surface to join the interosseous fasciae, and separate the middle of the palm from the external and internal lateral portions. The connexions of the palmar aponenrosis to the sheaths of the tendons below, and .to the annular . ligament above, explain the effects of inflammation when seated within the former, such as the pain and tension in the palm, the fulness on the dorsum, and the extension of the disease to the forearm beneath the annular ligament. A thin aponeurosis, derived from the outer edge of the palmar fascia, covers the muscles oftine-thmnb. an d a similar one ,. ., M 2 fVtf THf \ f UNIVERSITY i 164 DUBLIN DISSECTOR. fig. those of the little finger. Attached to the palmar fascia is the following small cuta- neous muscle. PALMARIS BREVIS arises from the an- nular ligament and from the inner edge of the palmar fascia; the fasciculi pass transversely inwards, and are inserted by scattered fibres into the integuments on the inner side of the palm of the hand. Use, to deepen the hollow of the palm of the hand by drawing the integuments towards the thumb ; it covers the ulnar artery and nerve, and passes across the muscles of the little finger. We have no analogous muscle to this in the foot. We may now dissect off the fascia of the hand and forearm, to expose the muscles; in some situations it is difficult and indeed unnecessary to separate this from the muscular fibres ; beneath the palmar fascia we expose the superficial palmar arch of vessels and nerves passing across the flexor tendons and the lumbricales mus- cles. The muscles of the forearm are so very numerous, that it will be found convenient to class them according to their situations and their use. One set of these muscles is employed in bending the forearm, wrist, and fingers : these are the flexors : a second, nearly allied to these, have the power of pronating the hand, that is, of rolling the radius across the ulna, so as to make the palm of the hand look down- wards ; these are the pronator s : a third set, the extensors, can extend the forearm, hand, and fingers ; and a fourth, allied to * The superficial muscles on the anterior as- pect of the forearm. 1. The biceps muscle. 2. The inferior portion of the brachialis anticus muscle. 3. Inferior extremity of the external portion of the triceps. 4. The pronator teres muscle. 5. Portion of the supinator brevis muscle. 6. The flexor carpi radialis muscle. 7. The palmaris longtis muscle. 8. The insertion of the tendon of the palmaris longus into the palmar fascia and anterior annular ligament. !). The palmar fascia or aponeurosis. 10. 10. The anterior annular ligament. 11. 11. The flexor digitorum sublimis muscle. 12. The flexor carpi ulnaris muscle. 13. The pisi- form bone. 14. The supinator radii longus muscle. 15. Portion of the flexor pollicis longus muscle. 16. The palmaris brevis muscle. 17. The tendon of the extensor ossis metacarpi pollicis. 18. Portion of the pronator quadratus muscle. ]>l I1LIX DISSECTOR. 165 them, the ttiipinatom, can turn the hand supine; that is, place the radius and ulna on the same plane, and make the palm of the hand look upwards. The pronators and flexors arise chiefly from the in- ternal condyle, and from the inner or ulnar side of the forearm ; each of th.'s,. divisions may be arranged into a superficial and deep layer. The pronators and flexors, arising from the inner side of the fore- arm, are eight in number; five in the superficial layer, three in the deep ; the five superficial are, the pronator teres, flexor carpi radialis, palmaris lorigus, flexor digitorum sublimis, and flexor carpi ulnaris : the three deep muscles are the flexor digitorum profiuidus, flexor pol- liris longus, and pronator quadratus. In the following description of these muscles, the hand is supposed to be turned forwards, the radius externally, and the ulna internally ; the elbow joint above, and the hand and lingers below; the words "internal" and "external" are used synonymously with " ulnar" and " radial ;" and like the terms " abduction" and " adduction," are referred to the median line of the body; in the dissection, however, of some of the palmar and digital miiM-les, these latter terms have reference to the middle line of the hand, and not to that of the body. The muscles which arise from the internal condyle of the humerus are covered by the fascia of the bi- ceps ; they cannot be separated from each other above, but have a common tendinous origin from the condyle, the fascia, and its septa, al>o from the ulna. PROXATOR RADII TERES arises tendinous and fleshy from the an- terior part of the internal condyle, from the fascia of the forearm, and its intermuscular septa ; also by a small tendon from the coronoid process of the ulna, which lies between the median nerve and the ul- nar artery ; the nerve separates these origins ; the fibres pass ob- liquely outwards over the radius, and are inserted, chiefly tendinous, into the outer and back part of the radius, about its centre. Use, to pronate the hand, by rolling the radius forwards and inwards over the ulna ; it is also a flexor of the forearm : this is the most external of the muscles arising from the inner condyle ; it is superficial, except at its insertion, which is covered by the supinator longus, and by the radial vessels, and is inferior to the supinator brevis ; this muscle forms the internal boundary of the triangular hollow at the bend of the elbow, which contains the tendon of the biceps, the brachial nerve and vessels. FLEXOR CARPI RADIALIS arises narrow and tendinous from the inner condyle, and fleshy from the intermuscular septa ; it forms a thick belly, which lies very superficial, and ends in a prominent flat tendon which is equally so : this descends obliquely outwards, passes beneath or through the annular ligament, and is inserted into the base of the me- tacarpal bone of the index finger. Use, to bend the hand, wrist, and forearm ; it also assists in pronation ; it may also abduct the hand. This muscle is overlapped above by the pronator teres, and covered below by the annular ligament and by the muscles of the thumb, so that its insertion cannot be seen until the palm of the hand has been 1 ; it arises and descends at first between the pronator teres 166 DUBLIN DISSECTOR. and palmaris longus, afterwards between this latter and the supinator longus, from which it is separated by the radial nerve and vessels : the radial edge of this tendon may serve as a guide in cutting down on the radial artery in the living subject. PALMARIS LONGUS arises by a slender tendon from the inner con- dyle, and from the fascia of the forearm ; forms a short belly, which ends in a flat tendon ; inserted near the root of the thumb into the annular ligament and palmar aponeurosis. Use, to bend the hand and make tense the palmar fascia ; it descends between the flexor carpi radialis and ulnaris, and lies on the flexor sublimis, from which it is separated by a strong fascia. This muscle is sometimes wanting ; occasionally it arises deep, in which case it is covered in the upper two-thirds of the forearm by the flexor sublimis. FLEXOR CARPI ULNARIS arises tendinous from the internal con- dyle, tendinous and fleshy from the inner side of the olecranon process ; the ulnar nerve and posterior ulnar recurrent arteries separate these origins ; it also arises by a tendinous expansion from the inner edge of the ulna nearly its whole length, and from the fascia of the fore- arm ; the fibres pass obliquely forwards to a tendon which descends in front of the ulna, and which overlaps the ulnar nerve and vessels, and is inserted into the pisiform bone, and by a few ligamentous fibres into the base of the fifth metacarpal bone ; this insertion is also con- nected to the muscles of the little finger. Use, to flex the hand, and adduct it, particularly when assisted by the extensor carpi ulnaris ; adduction of the hand is not so limited as abduction, in consequence of the ulna being shorter below than the radius. This muscle is super- ficial, and lies internal and rather posterior to the preceding muscles ; it descends between the flexor sublimis and extensor carpi ulnaris, and lies upon the flexor profundus ; the tendon passes over the annular li- gament, and is connected to it by a tendinous slip which also passes over the ulnar artery and nerve. FLEXOR DIGITORUM SUBLIMIS PERFORATUS, arises tendinous and fleshy from the internal condyle and internal lateral ligament ; tendi- nous from the coronoid process and fleshy from that portion of the radius which is below its tubercle, and internal to the pronator teres, and between the supinator brevis and flexor pollicis longus : it forms a large muscle, which ends in four tendons ; these descend, two an- terior, for the middle and ring finger; and two posterior, for the index and little finger ; they all pass beneath the annular ligament, along with the median nerve, to their outer side ; they occupy the inner half of this space, and are close to the unciform bone ; they then proceed diverging along the palm of the hand, superficial to the deep flexor tendons, and beneath the palmar fascia ; and at the first phalanx of each finger, or opposite the head of each metacarpal bone, each of these tendons becomes enclosed in a strong sheath, with one of the deep flexors, and is slightly concave over it ; this sheath is continued to the anterior extremity of the second phalanx. Near the end of the first phalanx each of the superficial flexor tendons is split for the pas- DUBLIN DISSECTOR. 167 sage of the teadon of the deep flexor, which is continued on to the last or unguul phalanx : while the divisions of each of the superficial tendon.-; In-come somewhat twisted, that is, the inner or opposed edges f the slit are everted or folded out heneath the deep flexor, so as to lie nearer to the bone and to the joint, connected together by cross slips, and are inserted by two processes into the anterior margins of the second phalanx about its centre. Use, to flex the second joint of each linger on the hand, the hand on the forearm, and the latter on the arm. The origin of this muscle is partly concealed by the three first described muscles, which arise from the inner condyle, and to which it is connected by the intermuscular septa ; inferiorly a portion of it is superficial between the flexor carpi ulnaris and palmaris longus ; above it covers the uhiar vessels and nerve, which separate it from the profundus ; it also covers the median nerve and the flexor pollicis lon- gus, to which it is often connected by a fleshy slip. The tendons are enveloped in the carpal bursa behind the annular ligament. In the palm of the hand they are covered by the integuments, palmar fascia, and the superficial palmar arch of vessels and nerves ; above the metaearpo-plmlangal joints, these, together with the deep tendons and the lumbricales, are bound down by the fibrous sheaths and arches formed by the septa of the palmar fascia, and immediately after, and through the rest of their course along the fingers each tendon is enclosed in a strong fibrous sheath, which is continued to the end of the second pha- lanx. The sheaths for the flexor tendons require special attention, they are covered by the integuments, and laterally by the digital ves- sels and nerves ; one or two may be dissected ; each of these sheaths is an osteo-fibrous canal or tube ; the flat surface of the phalanges forming one Avail, the remainder composed of strong semicircular fibres, interlaced, and of a pearly colour, very dense opposite the phalanges, but thin, and even deficient over the angles of the articulations ; they commence beyond the metacarpo-phalangal joints, and are connected to their ligaments, and terminate above, between those of the second and last, or ungnal phalanx, by intermingling with the deep flexor ten- dons ; these tubes preserve their form even when the tendons have been removed ; the fibres are arranged in semicircular fasciculi, and are attached to each border of the phalanges ; open one of these sheaths, and the whole tube will be found lined by a synovial mem- brane, which is prolonged for some distance into the palmar region, and is reflected round these two tendons, enclosing each, and forming two or three triangular folds or retinacula, one posteriorly near the base of the first phalanx, and extending from one tendon to the other; another more anterior, passes from the split in the superficial to the deep tendon ; and the others pass from the deep tendon to the bone ; these bursuj end in two cul de sacs, one in the palm, the other at the extremity of the second phalanx; the retinacula sometimes contain fibrous cords, they resemble the synovial folds in the knee joint, and may be designed partly to support the tendons, and partly to convey nutritious vessels to the different tissues. These sheaths are very 108 DUBLIN DISSECTOR. Fig. 32. * useful in confining the tendons close to the phalanges, and preventing their starting forwards in the action of the muscles, the latter also, in consequence of their connexion to the metacarpo- phalangal joints, are enabled to flex the first phalanges and the metacarpus, which possesses no distinct flexor, un- less the flexor carpi radialis may be so considered. Divide the flexor sublimis and carpi radialis, and the three deep muscles will be partially exposed, namely, the flexor digitorum profundus, flexor pol- licis longus, arid, nearly concealed by these, the pronator quadratus. FLEXOR DIGITORUM PROFUNDUS PERFORANS arises fleshy from three superior fourths of the anterior surface of the ulna, and from the internal half of the interosseous ligament ; it sometimes receives a small slip from the radius below its tubercle ; it forms a thick muscle which descends along the middle and ulnar side of the fore- arm, betw r een the flexor ulnaris and flexor pollicis, and ends in four flat ten - * The muscles on the anterior aspect of the forearm, part of the superficial layer having been removed. 1. The inferior ex- tremity of the biceps muscle and its tendon, inserted into the tubercle of the radius. 2. The lower part of the brachialis anticus muscle, inserted into 3. The coronoid pro- cess of the ulna. 4. The internal condyle of the humerus. 5. The external condyle of the humerus. 6. The supinator brevis mus- cle. 7. The flexor digitorum sublimis mus- cle. 8. Its attachment to the internal con- dyle of the humerus. 9. Its attachment to the coronoid process of the ulna. 10. The attachment of the same muscle to the an- terior surface of the radius. 11. The four tendons of the flexor digitorum sublimis. 12. The four tendons of the flexor digi- torum profundus, lying beneath the ten- dons of the superficial flexor. 13. 13. The split in the superficial tendons through which the tendons of the deep flexor pass. 14. The tendon of the deep flexor, divided and drawn downwards to shew the disposition of the correspond- ing tendon of the superficial flexor. 15. A tendon of the deep flexor inserted into the last phalanx. 16. The flexor carpis ulnaris muscle. 17. The pisiform bone. 18. The hook of the nnciform bone. 19. The flexor pollicis longus. 20. Its tendon passing between the two portions of the short flexor to the last pha- lanx of the thumb. 21. The pronator quadratus muscle. 22. The abductor pol- licis muscle. DISSECTOK. 169 duns: these pass beneath the annular ligament, enter the ligamentous >lieaths on the lingers, pass through the slits in the superficial flexor tendons, and are inserted into the last phalanx of each finger. Use, to bend the last phalanx, and to cooperate with the superficial flexor muscle in bending the other phalanges and the wrist ; this muscle is covered by those of the superficial layer, which have been described ; the ulnar vessels, the median and ulnar nerves, also descend along it ; and it covers the ulnji, the interosseous ligament and vessels, the pro- nator quadratus, and the carpus; beneath the annular ligament the tendons are placed behind those of the sublimis, and separated from them by folds of the carpal bursa ; these deep tendons are not so dis- tinct and separate as the superficial, but are united more or less by tendinous bands ; that for the index finger, however, is usually dis- tinct from the others, analogous hi this respect to its extensor tendon ; on each finger its tendon is superficial to that of the flexor sublimis after its transit through the slit ; this portion of the tendon is marked by a longitudinal groove, and a retinaculum passes back from it to be in- serted into the first phalanx. As the lumbricales muscles may be considered as accessory to the deep flexor, they can be now ex- amined, or their dissection may be postponed until that of the other palmar muscles. LUMBRICALES are four in number, small, round, and fleshy, with long delicate tendons ; they arise from the outer and radial side of the tendons of the flexor profundus, near the carpus, a little beyond the annular ligament ; they each form a small fleshy belly, which ends in a tendon ; this runs along the radial side of the finger, joins the ten- don of the corresponding interosseous muscle, and is inserted about the middle of the first phalanx into the tendinous expansion which covers the back part of each finger. Use, to assist in bending the first joint of the finger ; they cannot do so unless the flexors are tense ; they can also adduct and abduct the fingers, and when the common ex- tensor muscle is in action, they may assist in extending them ; they may also prevent the displacement of the flexor and extensor tendons ; these small muscles axe covered by the superficial flexor tendons, palmar vessels, and nerves ; the first is the largest, the fourth the smallest ; the two middle run nearly parallel, but the internal and external diverge ; the tendons of the lumbricales frequently divide into two portions : one of these will be inserted into the first phalanx, the other into the posterior tendinous expansion. FLEXOR POLLICIS LOXGUS arises from the forepart of the radius, commencing narrow just below its tubercle, and from the interosseous membrane, to within about two inches of the carpus, it also very fre- quently arises by a long and narrow tendinous and fleshy slip from the coi'onoid process ; this at first looks like a distinct muscle ; all the fibres descend obliquely forwards to a tendon Avhich passes beneath the annular ligament, close to the carpus, behind the median nerve, external to the deep flexor tendons, and surrounded by a distinct sy- novial membrane, it then runs outwards between the two portions of the 170 DUBLIN DISSECTOR. short flexor, and the two sesamoid tuber- cles at the extremity of the metacarpal bone ; it next enters a strong ligamentous sheath lined by a bursa, and is confined by it as far as the last phalanx of the thumb, into the middle of which it is inserted. Use, to flex and adduct the different joints of the thumb upon the hand, and the latter upon the forearm. This muscle is covered by the flexor sublimis and radialis, and by the radial vessels, and inferiorly by the an- nular ligament, it descends along the radial side of the flexor profimdus. PROXATOR QUADRATUS is exposed by separating the flexor pollicis and profundus ; it is a small, square muscle, situated just above the carpus, and arises tendinous and fleshy from the inferior fifth of the internal and anterior surface of the ulna ; the fibres pass transversely outwards, winding round the ulna, and descend a little to be inserted into the anterior part of the inferior fourth of the radius. Use, to roll the radius over the ulna, and so to pronate the hand; this muscle is covered by the tendons of the preceding, and by the ulnar and ra- dial vessels, and it lies on the interosseous ligament, the radius, and the ulna. The muscles which are situated on the outer and back part of the forearm are supinators and extensors, and are also ar- ranged into two layers, a superficial and a deep ; the superficial consist of seven, namely, supinator radii longus, extensor * The superficial layer of muscles on the pos- terior aspect of the forearm. 1. The external condyle of the humerus. 2. The olecranon pro- cess of the ulna. 3. The supinator radii lon- gus muscle. 4. The extensor carpi radialis longus. 5. The extensor carpi radialis bre- vis. 6. The insertion of the tendon of the ex- tensor carpi radialis longus into the second metacarpal bone. 7. The insertion of the tendon of the extensor carpi radialis brevis into the third metacarpal bone. 8. The extensor digitorum communis muscle. 9. The extensor minimi digiti. 10. The extensor carpi ulnaris. 11. The anconajus muscle. 12. Part of the flexor carpi ulnaris. 13. The extensor ossis metacarpi pollicis. 14. The extensor primi internodii pollicis. 15. The tendon of the extensor sccimdi inter- nodii pollicis. 16. The posterior annular ligament of the carpus. 17. The ten- don of the extensor indicis. 18. The first dorsal interosseous muscle. The other three dorsal interosseous muscles are seen between the metacarpal bones of the other fingers. 19. Part of the adductor pollicis. 20. The muscles of the little finger. Dl'IJI.IX DISSECTOR. 171 carpi radialis longus, and brevis, extensor digitorum communis, ex- tensor minimi digiti, extensor carpi ulmiris and anconaeus; these mus- cles arise more distinctly than those on the internal side of the arm; sonic of them, however, particularly those on the back part, are closely connected to each other, arising in common from the external condyle of the humerus, from the posterior surface of the radius and ulna, also from the intermuscular ligaments and the fascia, which is partly derived from the tendon of the triceps. Sri-ixATOu RADII LOXGUS forms the prominence along the outer and anterior part of the forearm, arises tendinous and fleshy from the external ridge of the humerus, commencing a little below the deltoid, as high as the musculo-spiral groove, and continuing to within about two inches of the outer condyle ; it also arises from the intermuscular ligament, which separates it from the second or outer head of the tri- ceps, between which and the brachiseus anticus this muscle is situated. The supinator longus descends along the outer and anterior part of the elbow, and about the middle of the forearm ends in a flat tendon, which descends along the radius, and is inserted into a rough surface on the outside of that bone, near its styloid process, and sends off an expansion to line the groove for the extensor tendons of the thumb. f/A-e, to roll the radius backwards, so as to make the hand look supine ; it can also bend the elbow joint. When the forearm is extended and supinated, it is then a flexor of the elbow, but when the limb is pro- nated, it is then a powerful supinator ; it can scarcely ever act as an extensor ; it may have some influence as an abductor. This muscle is superficial ; it passes over the extensor carpi radialis longus above, the tendon of the pronator teres in the middle, and the radius infe- riorly ; its tendon descends at first between the pronator teres and extensor radialis longus, afterwards between the latter and that of the flexor carpi radialis ; at its insertion it is crossed by the extensor ten- dons of the thumb ; the cephalic vein and external cutaneous nerve lie between it and the biceps ; the musculo-spiral nerve and artery between it and the brachia3us anticus. This muscle and its tendon overlap the radial nerve and vessels ; its ulnar edge, therefore, will serve as a guide to the latter, in case we are required, during life, to expose them, in order to tie a ligature around the radial artery. EXTENSOR CARPI RADIALIS LONGUS arises tendinous and fleshy from the ridge on the external side of the humerus, between the su- pinator longus and the external condyle ; it forms a thick, short belly which passes over the outside of the joint, ends in a flat tendon, which descends along the outer and back part of the radius, runs through a groove on its lower extremity, and, passing over the wrist joint, is in- serted into the back part of the carpal end of the metacarpal bone of the index finger, nearly opposite to that of the flexor carpi radialis. / r *e, it extends the wrist, bends the hand backwards, and abducts it a little; it may also assist in bending the elbow joint ; its belly is covered by the last described muscle, but projects beliind it; the ten- don descends behind that of the supinator longus, and passes beneath 172 DUBLIN DISSECTOR. the extensors of the thumb and the annular ligament ; it covers the supinator brevis and the following muscle. EXTENSOR CARPI RADIALIS BREVIS arises tendinous and fleshy from the inferior and posterior part of the external condyle, and from the external lateral ligament, forms a thick belly, which descends along the back part of the radius, ends in a flat tendon, which runs through the same groove as the tendon of the last muscle, internal to which it lies : this groove is lined by a bursa, and is partly divided by a bony ridge; the tendon then passes beneath the annular ligament, and is inserted into the carpal extremity of the third metacarpal bone, or that of the middle finger. Use, similar to that of the last ; it is covered superiorly by the last described muscle, and by the supinator longus, and below by the tendons of the extensor muscles of the thumb, and by that of the last muscle, and by the skin ; it covers the supinator brevis and the insertion of the pronator teres. EXTENSOR DIGITORUM COMMUNIS is situated more towards the back part of the forearm than the last described muscles ; it arises, in common with the last, and with the extensor minimi digiti, from the external condyle, the fascia, and its intermuscular processes, also from the ulna ; it descends along the back of the forearm, and about the middle of the latter ends in four muscles, each of which ends in a ten- don ; these pass under the annular ligament in a groove in the radius, extend along the back of the hand, expanding as they approach the four fingers, into all the phalanges of which they are inserted by a tendinous expansion. Use, to extend all the joints of the fingers, also the carpus ; this muscle arises between the extensor carpi radialis brevis and extensor minimi digiti ; it descends superficially between these, and over the supinator brevis and extensors of the thumb ; on the back of the hand the tendons are connected to each other by cross slips, but the tendon of the index finger is generally free ; that which goes to the ring finger is the largest, and a strong transverse band often connects it to that of the little finger: all the tendons, as they approach the base of the first phalanx, become thick but narrow, and give off a fibrous expansion on each side to cover the joint; after- wards they enlarge and are joined by the tendons of the lumbricales and interossei ; at the articulation of the first and second phalanx each divides into three bands ; the middle one is inserted into the posterior surface of the upper end of the second phalanx ; the lateral pass along the sides of this articulation ; they afterwards converge and unite in a flat tendon, which is inserted into the base of the last or third pha- lanx. The back part of all the fingers is covered, so far as the last phalanx, by a tendinous expansion, derived from these tendons, and from those of the lumbricales and interossei muscles. EXTENSOR CARPI ULNARIS is very superficial, arises tendinous and fleshy between the extensor minimi digiti and .anconaeus, from the ex- ternal condyle, fascia, and intermuscular septa ; descends obliquely in- wards, between the flexor ulnaris and extensor minimi digiti, towards the ulna, and receives an addition from it ; it ends in a strong tendon, DUIJI.1X DISSECTOK. which runs through a groove on the back of the /'/;/. 86.* ulna, tlion beneath tlie annular ligament, and heliiiul the cuneiform bone, and is inserted into the carpal end of the fifth metacarpal bone. Use, to extend the hand and bend it backwards ; also to adduct it, that is, nex it laterally towards the ulna. AxcoN.Krs, small, triangular, and placed at the outer side of the olecranon, beneath the skin ; n rises from the posterior and inferior part of the external condyle and lateral ligament by a very distinct tendon, also by some fleshy fibres from the lower border of the triceps, forms a thick triangular mass, which adheres to the synovial membrane, and descends obliquely inwards, to be inserted into the external surface of the ole- cranon, and about the superior fifth of the pos- terior surface of the ulna. Use, to extend the forearm on the arm, and to raise the synovial membrane out of the articulation ; this muscle is partly covered by the tendon and aponeurosis of the triceps ; the remainder of it is superficial ; it is situated between the olecranon and the ex- tensor carpi ulnaris ; it often appears as a con- tinuation of the triceps ; it covers a portion of the radio-humeral joint, of the coronary ligament, and of the supinator brevis. EXTENSOR MINIMI DIGITI, vel AURICULARIS, arises in common with the extensor communis, and descends between it and the extensor carpi ulnaris ; it forms a small fleshy belly, which descends very obliquely inwards, and ends in a slender tendon ; this passes through a separate groove hi the radius, and also through a distinct division of the annular ligament, in which situa- tion it is frequently found divided into two, which continue hi contact, and afterwards unite : this tendon becomes attached to the fourth tendon of the extensor communis, and is inserted along with it into the posterior part of the phalanges of the little finger. Use, to assist the extensor communis, and to extend and abduct the little finger independent of the others. * The deep layer of muscles on the posterior aspect of the forearm. 1. The external condyle of the humerus. 2. The olecranon process of the ulna. 3. The supinator radii longns. 4. The extensor carpi radialis longus. 5. The extensor carpi radialis brevis. 6. The anconseus. 7. The supinator radii brevis. 8. The posterior surface of the radius. 9. The posterior surface of the ulna. 10. Portion of the flexor carpi ulnaris. 11. Extensor ossis metacarpi pollicis, or abductor pollicis longus. 12. The insertion of its tendon into the metacarpal bone of the thumb. I-'). The extensor primi intemodii pollicis. 14. The extensor secundi internodii pollicis. 15. The extensor indicis. 16. The inferior portion of the tendon of the extensor carpi ulnaris. 174 DUBLIN DISSECTOR. The deep muscles in this situation are five in number, they will be exposed by removing the superficial layer ; they consist of the supina- tor radii brevis, three extensors of the thumb, and the indicator. SUPINATOR RADII BREVIS, short and flat, surrounds the upper part of the radius, arises from the external condyle, extenial lateral, and coronary ligaments, and from a ridge on the outer side of the ulna, which commences below its lesser sigmoid cavity ; the fibres adhere to the capsular ligament, and descend obliquely outwards and for- wards round the upper part of the radius, and are inserted into the upper third of the external and anterior surface of this bone, from above its tubercle down to the insertion of the pronator teres. Use, to turn the radius outwards, so as to make the hand look supine, which it can effect with great power ; it can also assist in extending the forearm. This muscle nearly surrounds the upper part of the radius, it is covered by the supinator longus, the radial extensors of the carpus, and the extensor digitorum communis externally ; by the anconaeus and extensor ulnaris posteriorly ; and anteriorly by the radial nerve and vessels, and by the brachiaBus and biceps ; it partly surrounds the humeral and ulnar articulations of the radius ; its an- terior edge is notched above for the insertion of the biceps, and is overlapped by the pronator teres below ; it is perforated by the pos- terior interosseous nerve. EXTEXSOR Ossis METACARPI POLLICIS, or ABDUCTOR POLLICIS LONGUS, arises fleshy from the middle of the posterior part of the ulna, below the anconaeus, also from the interosseous ligament and posterior surface of the radius below the supinator brevis ; it de- scends outwards and forwards, and ends in a tendon, which passes through a groove on the outside of the lower end of the radius, runs by the side of the carpus, and is inserted in general by two tendons, one into the os trapezium, and the other into the upper and back part of the metacarpal bone of the thumb. Use, to extend the first joint of the thumb, and separate it from the fingers ; it also extends the wrist, and abducts the hand ; it can also assist in supination. The origin of this muscle is concealed by the extensor communis and carpi ulnaris ; the tendon is superficial and passes over the tendons of the radial extensors of the carpus, also over the radial vessels. I have sometimes found a second muscle analogous to this, but arising so high as from the external condyle of the humerus, and ending in a very long slender tendon which accompanied that of the last muscle, and inserted along with it into the metacarpal bone of the thumb. EXTENSOR PRIMI INTERNODII POLLICIS, or EXTENSOR MINOR, arises from the back part of the ulna, below its middle, and from the interosseous ligament and radius ; it descends along the ulnar side of the last muscle ; its tendon passes through the same groove in the ra- dius, and bound down by the same portion of the annular ligament, and is inserted into the posterior part of the first phalanx ; a small slip is often continued on to the second phalanx. Use, to extend the second joint of the thumb, and to assist the last described muscle ; its connexions are also similar. Dfl'.LlN DISSKCTOR. 175 EXTKNSOU Six IXDI IXTKRXOPII Poi.Licis, or EXTENSOR MAJOI:, f//-/,sT.s' from the posterior surface of the ulna above its centre, and from the interosseons membrane; its belly overlaps the two former muscles, its tendon passt-s along a distinct groove in the radius, runs over the outer side of the wrist, the metacarpal bone, and first phalanx of the thumb, and is inserted into the posterior part of the second or last phalanx. Use, to extend the last phalanx of the thumb upon the first, and to assist the former muscles in extending and stipulating the hand. The tendon of this muscle is separated from the two former, on the outer and back part of the wrist, by a small space distinct through the skin, in which we perceive the tendons of the radial ex- tensors of the carpus, and the radial artery ; the relations of this mus- cle in other respects are nearly similar to those of the other extensors of the thumb. EXTENSOR IXDICIS, or INDICATOR, arises from the middle of the posterior surface of the ulna and interosseous membrane ; its tendon passes under the annular ligament along with those of the common extensor, is attached to the radial side of that tendon which belongs to the forefinger, and is inserted along with it into its second and third phalanges. Use, it assists the common extensor, or produces the ex- tension of the forefinger alone, as in pointing. This muscle is con- cealed by the extensor communis and ulnaris, lies to the ulnar side of the extensor pollicis major, and its tendon passes under those of the common extensor, to which it is sometimes connected by a tendinous slip. Xext dissect the muscles of the hand, which consist, externally, of the muscles of the thumb ; internally, of those of the little finger, and in the middle of the lumbricales superficially, and the interossei, deep-seated ; the lumbricales, or the accessories to the flexor profundus, have been already examined. In conducting the dissection of this region, the student should make frequent and careful reference to its skeleton ; we may observe that few portions of the animal frame present more interesting characters for minute anatomical examination than the human hand, as it, most probably, affords the best example that could be adduced, not only of superiority in the human organization, when contrasted with that of any other created being, but also of the most perfect adaptation of structure to function, of means to an end, of design in a plan, and of perfection hi its execution. The great number of small bones, twenty- seven in all, with their joints and ligaments so securely connected, and so neatly adapted, as to combine the opposite qualities of strength and freedom of motion, all collected into so small a space with the nume- rous long and slender tendons, elegantly shaped, and each confined in its appropriate highly polished sheath or groove; the muscles of these, some large and strong, others small and weak, all linked together in the closest sympathy, and endowed witli powers of executing the most varied motions, delicate, yet rapid, powerful, yet enduring, often in- stinctive, and, as it were, without our thought or cognizance, yet are all these muscles voluntary and wonderfully capable of education and improvement, so as to become, not only the principal agents in most 176 DUBLIN DISSECTOR. of the physical acts of life, defensive or offensive, but also the immediate instrument in the production of every work of art, thereby, in a great mea- sure, pourtraying the feelings of the mind, and the powers of the intellect. The large supply of bloodvessels and of nerves, impairing the highest sensibility, and the most exquisite delicacy of tact and feeling, and these properties, too, residing in a part necessarily, and almost con- stantly exposed to violence or inj ury ; these, and many other circum- stances connected with the organization and the functions of the hand, are eminently calculated to excite our curiosity, and, when fully and properly investigated, cannot fail to ensure admiration and re- spect. The eight bones of the carpus, small, and of irregular forms, are Fig. 35.* * The muscles of the hand. 1. The anterior annular ligament. 2. The ab- ductor pollicis muscle divided close to its attachment to the annular ligament and tin-own downwards. 3. The flexor ossis metacarpi, or opponens pollicis. 4. The anterior, or exernal portion of the flexor pollicis brevis. 5. The posterior, or in- ternal portion of the same muscle. 6. The tendon of the flexor pollicis longus. 7. The adductor pollicis. 8. Portion of the first dorsal interosseons muscle. 9. Tendons of the flexor digitorum profundus. 10. The four lumbricales muscles. 11. The abductor minimi digiti. 12. The flexor breyis minimi digiti. 13. The opponens or adductor minimi digiti. 14. The os pisiforme. DUBLIN DISSECTOR. 177 compacted into an arch, which, by means of the annular ligament, is converted into a ring, thus this weak pile of hones acquires much strength, and a secure passage is provided for the tendons, vessels, and nerves. The nineteen metacarpal and phalangal hones, by their great length, add considerably to the length of the hand, and extend the sphere of its motions. The metacarpus is arched towards the palm in. both directions, thereby imparting that degree of strength which it requires as a medium for supporting the weight of the body, as is oc- casionally required, and at the same time fitting it the better to serve as an organ of prehension ; this cup-like form of the palm is beauti- fully completed by the muscular ball of the thumb externally, and by the muscles of the little finger internally ; the very limited motions of the metacarpus on the carpus secure this form permanently, while the arthrodial metacarpo-phalangal joints admit of motion in all di- rections, and the gynglymoid phalangal articulations allow of no mo- tion laterally or backwards beyond the line of extension, but can be flexed to a right angle, thus serving either to close the hand com- pletely, or to be used as instruments of touch with firmness and pre- cision ; the last phalanx is peculiarly shaped and flattened, so as to support the nail behind, and the pulpy organized apparatus for the sense of touch in front. The short muscles of the thumb are four in number, viz., the ab- ductor, opponens, flexor brevis, and adductor pollicis. Ar.nrcTOR POLLICIS arises broad and thin from the anterior part of the annular ligament, os naviculare, and trapezium, and from the tendon of the abductor longus, inserted into the outside of the base of the first phalanx, and by an expansion into the back of both pha- langes ; its name implies its use, to separate the thumb from the fin- gers ; it lies superficial, and is most external of these small muscles, which form the ball of the thumb. OPPONEXS POLLICIS, or FLEXOR Ossis METACARPI, arises from the annular ligament and os naviculare ; inserted into the anterior ex- tremity of the metacarpal bone of the thumb. Use, to approximate the thumb to the fingers ; it is internal to and partly overlapped by the last muscle ; it lies on a part of the annular ligament, and of the following muscle, from which it is separated with difficulty. FLKXOR POLLICIS BREVIS, consists of two portions, between which is the tendon of the flexor longus ; one head, the external or anterior, arises from the inside of the annular ligament, and from the trapezium and scaphoid bones, passes outwards, and is inserted into the external sesamoid bone, or cartilage, and base of the first phalanx of the thumb ; the second, or internal or posterior, arises from the os magnum, from the base of the metacarpal bone of the middle finger, and from the sheath of the flexor carpi radialis ; it also passes outwards, distinct from the other at first, but afterwards united to it, and inserted into the internal sesamoid bone, and base of the first phalanx. Use, to flex the first phalanx and metacarpal bone on the carpus ; this muscle is concealed by the two former, and by the first lunibricalis ; it covers the two first 178 DUBLIN DISSECTOR. interossei muscles, and the tendon of the flexor carpi radialis ; its outer edge is connected to the opponens pollicis, and the internal to the ad- ductor. ADDUCTOR POLLICIS, triangular and broad, arises fleshy from three- fourths of the anterior surface of the third metacarpal bone, or that of the middle finger ; the fibres pass outwards over the second metacarpal bone, and converging are inserted into the inner side of the root of the first phalanx of the thumb, along with part of the last muscle ; its name denotes its use. This muscle at its origin is covered anteriorly by the deep flexor tendons and by the lumbricales ; its insertion is co- vered by the abductor indicis. The adductor pollicis may be regarded as the first of the anterior interossei ; it is, however, much stronger than any of that group, and differs from them in passing over one metacarpal bone between its origin and insertion ; this is for the pur- pose of increasing the extent of adduction of the thumb. The number and strength of the muscles of this finger, as well as the peculiarity of its carpal articulation, render it eminently useful, and altogether supe- rior to the corresponding member hi any other animal, even in the highest of the quadrumana ; it possesses two flexors, three extensors, one of which is a powerful abductor, also a short abductor, an oppo- nens, and a very strong adductor ; the alternate, combined, or varied actions of these muscles can move the thumb in all directions. On the inner side of the palm of the hand are the short muscles of the little finger, which are three in number ; also the cutaneous muscle, palmaris brevis, which has been already examined. ABDUCTOR MINIMI DIGITI arises fleshy from the annular ligament and from the pisiform bone ; its fibres run along the ulnar side of the me- tacarpal bone, and are inserted tendinous into the ulnar side of the first phalanx ; its name implies its use ; it is superficial ; a few fibres of the palmaris only cover it ; its origin is partly continuous with the insertion of the flexor carpi ulnaris. FLEXOR BREVIS MINIMI DIGITI arises from the annular ligament and unciform bone, inserted by a round tendon into the base of the first phalanx of the little finger. Use, to flex and adduct the little finger ; it lies to the radial side of the last muscle, along with which it is inserted. ADDUCTOR, or OPPONENS MINIMI DIGITI, arises along with, but internal to the last, and overlapped by it, and is inserted into all the metacarpal bone of this finger : its name denotes its use. When all the flexor and extensor tendons have been removed, we observe the intervals between the metacarpal bones to be filled by muscular fibres, which are called the interosseous muscles. As there are four interosseous spaces, there must be eight of these muscles, two in each space, but one of the anterior set has been already described as the " adductor pollicis," differing from the interossei in passing across one metacarpal bone, as it proceeds from its origin to its inser- tion, in order to increase the extent of adduction of the thumb. One of the posterior set, also, is sometimes described as a distinct muscle, DUBLIN DISSECTOR. UP abductor indicia," therefore some only enumerate six interossei muscles, three anterior, and three posterior; we shall consider them .is seven in number, three in front and four behind : their actions on the lingers are chiefly adduction and abduction ; these terms are ap- plied in reference, not to the medial line of the body, as in the descrip- tion of other regions, but to the middle line or axis of the hand, which corresponds to the middle finger and its metacarpal bone ; ad- duction is the approximation of the fingers, abduction their divarica- tion. The anterior, or palmar interossei, are adductors ; their origin, or fixed point, being nearer the axis than their moveable insertion ; the posterior are abductors, their origin being further from the axis than their insertion, both also act on the extensor tendons, and keep these fixed to the dorsum of the fingers in the h'ne of their phalanges, thus answering the same purpose as the sheaths in front ; they may also, in consequence of this attachment, assist in the extension of the fingers, and hence it is that they have no power of acting, especially the posterior, unless the extensors are previously in action ; when the fingers are bent and the hand but partially closed, we cannot separate or abduct the fingers, but the mere act of flexion adducts them at the same time. The anterior, or palmar interossei, are three in number, the adductor pollicis being excluded ; they are placed on the metacar- pal bones, rather than between them, are covered anteriorly by the flexor tendons and the lumbricales, by the palmar vessels and nerves, and by the deep palmar fascia, from which septa pass between these and the posterior muscles, which also project into the palm ; posteriorly they are covered by the posterior interossei ; one side of each is at- tached to the metacarpal bone, and the other is in contact with the projecting posterior muscle, the thin fascia only intervening ; they each arise by a single, but a long origin, from one metacarpal bone, and are inserted into the first phalanx of the same finger, and into its extensor tendon ; the first is along" the ulnar side of the metacarpal bone of the index finger and inserted into its first phalanx, it will therefore adduct that finger towards the middle ; the second and third are along the radial sides of the metacarpal bones of the ring and little fingers, and, inserted into their first phalanges, will also adduct those fingers towards the middle finger ; the latter has no anterior interos- seous muscle attached to it, for obvious reasons, it being the axis towards which the other fingers are adducted. FIRST I'AT.MAK IXTEROSSEOUS, or ADDUCTOR INDICIS, arises by fleshy fibres from the two upper thirds of the ulnar side of the second metacarpal bone, and from the ligament connecting it to the trapezoid; these end in a small tendon which is inserted into the ulnar side of the base of the first phalanx of the forefinger and into the extensor aponeurosis. Use, to adduct this finger ; it is covered anteriorly by the adductor and flexor pollicis brevis ; the second dorsal interosseous is along its inner side. Si:< ONI) I'.VI.MAK INTEKOSSEOUS, or ADDUCTOR ANNULARIS arises in like manner as the last from the radial side of the fourth metacar- 180 DUBLIN DISSECTOR. pal bone, and is inserted into the radial side of the base of the ring linger and into its extensor tendon. Use, to adduct the ring finger towards the middle, THIRD PALMAR INTEROSSEOUS, or ADDUCTOR MINIMI DIGITI, arises from the radial side of the fifth metacarpal bone, and from the ligaments connecting it to the unciform ; inserted into the radial side of the base of the first phalanx of the little finger and into its extensor tendon ; it is covered by the opponens minimi digit! ; the fourth dorsal interosseous corresponds to its radial side. Use, to adduct the little to the ring and middle fingers. The posterior intcrossei are four in number ; they are longer and more distinct than the anterior ; they may be seen posteriorly, filling the metacarpal intervals, also an- teriorly projecting beyond the bones and connected to the anterior in- terossei ; the first is much the largest and is named the FIRST POSTERIOR INTEROSSEOUS, or ABDUCTOR INDICIS, between the thumb and forefinger ; thin, flat, and triangular, the base above, the apex at its insertion ; arises by two origins, each from the opposed sides of the first and second metacarpal bones ; a tendinous arch con- nects these posteriorly, behind which the radial artery passes into the palmar region ; the two fasciculi proceed distinct for some way, then end in a tendon which is inserted into the radial side of the base of the first phalanx of the index finger and into the border of its extensor tendon. Use, to move this finger from the others, or from the axis of the hand towards the thumb, it also draws it forwards towards the palm ; this muscle crosses behind the adductor pollicis and is subcu- taneous posteriorly ; it can be felt and seen in the triangular cutaneous fold between the thumb and index finger ; its palmar surface is in contact with the short flexor, and adductor of the thumb and first lumbricalis* SECOND POSTERIOR INTEROSSEOUS, or EXTERNUS MEDII, arises from the opposite sides of the second and third metacarpal bones, and is in- serted into the radial side of the middle finger, and into its extensor tendon. Use, to move the latter out-wards or towards the index. THIRD POSTERIOR INTEROSSEOUS, or INTERNUS MEDII, arises from the opposed sides of the middle and ring fingers, and is inserted, like the last, into the ulnar side of the middle. Use, to move the latter in- wards, or towards the ring finger ; thus the middle finger has two dorsal interosseous muscles ; which individually move it to either side, but when both act they fix it in the extended line ; this finger, there- fore, requires no anterior interosseous muscle. FOURTH POSTERIOR lNTEROssEous,or ABDUCTOR ANNULARIS, arises from the opposed sides of the fourth and fifth metacarpal bones, and is inserted into the ulnar side of the ring finger. Use, to separate this from the middle finger. No posterior interosseous muscle is inserted into the little finger, unless we regard its abductor muscle as one, its use being analogous, as it cooperates with the long abductor of the thumb, and with all the posterior intcrossei, in divaricating all the fingers, and thus enlarging the range of surface over which' the mssKCTOK. 181 liand and finders can extend. These three last interossei muscles are very similarly circumstanced, covered posteriorly by the integuments, the extensor tendons, and their connecting transverse hands, also by a tine fascia which binds them down on a plane with the metacarpal bones; they are all somewhat triangular, or prism-shaped, and their superior, or carpal extremities, are pierced by the perforating arteries from the deep palmar arch, in the same manner as the radial arteiy pierces that of the abductor indicis ; they all arise, by double origins, from two metacarpal bones, and are inserted singly into the first pha- lanx of one finger, and into its extensor tendon ; one origin is from the posterior lateral surface of one bone, and the other is from the en- tire side of the opposite ; the fasciculi are penniform, and proceed very obliquely, and their tendons pass over the metacarpo-phalangal joints and then expand as they join the extensor aponeuroses. All these muscles are covered in front by the palmar tendons, vessels, and nerves. From a review of the muscles of this region we may infer, that, as at the elbow, so at the wrist, hand, and fingers, the flexors predomi- nate over the extensors ; each of the four inner fingers possesses three flexors, the profundus perforans for the last phalanx, the sublimis perfomtus for the second, the accessory, or lumbricalis, for the first ; the latter may also flex the metacarpus, and the anterior interossei can assist these by pressing forwards the metacarpo-phalangal joints. The thumb has its long flexor, analogous to the pi'ofundus in the other fingers ; it wants, however, the second long flexor, as it has not the middle phalanx ; but it has a very strong short flexor, or accessory muscle, as also an opponens and an adductor, which cooperate with its flexors. Each of the four inner fingers has a long extensor, whose action is aided by the interossei and lumbricales ; the index and little finger have also an additional extensor ; and the thumb, in addition to the long abductor, or extensor of its metacarpal bone, has also an extensor for its first and for its second phalanx. The flexors have a tendency to adduct or approximate the fingers, and the anterior inter- ossei and lumbricales can cooperate ; while the extensors have a ten- dency slightly to abduct, and are greatly assisted in so doing by the posterior interossei. Although the thumb has no posterior iuteros- seous muscle, yet its long abductor, arising in the posterior interosseous space in the forearm, is analogous, but superior in power ; the index finger has its adductor, or anterior interosseous, and its abductor or posterior interosseous ; the middle, instead of an anterior, has two pos- terior interossei, which can fix it and move it to cither side, and therefore serves to abduct or adduct it ; the ring has its anterior inter- mi its posterior, or abductor ; and the little has the anterior intcrrossx-ou>, or adductor, and its abductor, which, how- ever, cannot be called an interosseous m;: In thu dissection of the forearm and hand Ave meet with the branches of the brachial artery, with their accompanying veins; also branches of the bnchial plexus of nerves : the cutaneous veins have 182 DUBLIN DISSECTOR. been already noticed. The brachial artery, when it arrives at the bend of the elbow, divides into its radial and ulnar branches. The radial artery descends from the elbow obliquely outwards, to the sty- loid process of the radius, passes over the outer side of the carpus, and then between the metacarpal bones of the thumb and of the forefinger, where it divides into three branches, radialis indicis, magna pollicis, and palmaris profunda : the radial artery at first lies between the pro- nator teres and supinator longus ; afterwards between the supinator and flexor carpi radialis ; it then winds round the carpus, over the external lateral ligament, and beneath the extensor tendons of the thumb ; in the forearm it is only overlapped above by the supinator longus ; in the rest of its course it is superficial ; it is accompanied by two veins, and by the radial branch of the musculo-spiral nerve, which lies to its outer side. The radial artery gives off, first, the re- current branch, which ascends in front of the external condyle, to supply the muscles attached there, and to inosculate with the superior profunda ; second, in its course down the forearm, several muscular branches ; third, near the wrist, the superficialis volae, which passes to the small muscles of the thumb, and communicates with the superficial palmar artery ; fourth and fifth, branches to the fore and back part of the carpus : and between the thumb and index finger it divides into its three last branches ; the magna pollicis subdivides, and supplies the sides of the thumb ; the radialis indicis, in like manner, supplies the forefinger ; and the palmaris profunda passes beneath all the flexor tendons across the four metacarpal bones, forms the deep palmar arch, and then joins a branch from the ulnar arteiy. The ulnar ar- tery is larger than the radial ; it descends obliquely inwards, beneath the superficial flexors and pronators, and lies on the flexor profundus ; it passes over the annular ligament into the palm of the hand, and there divides into a superficial and deep branch : this vessel is covered also by several muscles, inferiorly it is superficial, and lies between the tendons of the flexor sublimis and flexor carpi ulnaris ; it is attended by its two veins, and in the inferior two-thirds of the forearm by the uhiar nerve, which always lies to its ulnar side ; near the wrist this nerve is somewhat behind the artery. The ul- nar artery sends off, first and second, its recurrent branches ; the an- terior, small, ascends in front of the internal condyle ; the pos- terior, large, passes behind that condyle and joins the inferior pro- funda ; third, the interosseous artery, which passing backwards, divides into its posterior and anterior branch ; the posterior passes through the upper part of the interosseous space, and ascends in the substance of the anconasus ; the anterior interosseous descends between and beneath the flexor profundus and flexor pollicis, as far as the pro- nator quadratus, which it supplies, and is then lost on the carpus ; fourth, muscular branches ; fifth and sixth, to the back and front of the carpus ; and in the palm of the hand it terminates in the deep and superficial branch ; the former sinks between the muscles of the little finger, to join the deep palmar arch ; the superficial runs across l)f KLIN DISSKOTOl;. 1 ,S.'i the flexor tendons, forming the superficial arch, from the convex side of which, the long digital arteries arise ; these supply the three inner lingers See 1'ascular System. In addition to the cutaneous nerves already noticed, we find the median, ulnar, and musculo-spiral descench'ng in the forearm ; the median /icrre passes between the heads of the pronator teres, and de- scends beneath the flexor sublimis, giving off the anterior interosseous nerve, and branches to the muscles of the forearm; it passes beneath the annular ligament, appears superficial in the pahn of the hand near the thumb, and sends off digital branches, which accompany the digi- tal arteries to all the fingers, except the little and the ulnar side of the ring finger. The ulnar nerve winds round behind the internal condyle, between the heads of the flexor carpi ulnaris, and descends along the internal side of the ulnar artery to the hand, where it termi- nates, by dividing into a small superficial and a large deep branch. The musculo-spiral or radial nerve, is seen beneath the supinator longns, descending along the outer side of the radial artery, and sup- plying the adjacent muscles ; near the elbow it gives off the posterior interosseous nerve, and a little below the middle of the forearm it passes beneath the tendon of the supinator, and becomes cutaneous, being distributed to the integuments of the thumb and back of the hand. See Anatomy of the Nerwnti System. 184 DUBLIN DISSECTOR. CHAPTER VI. DISSECTION OF THE ABDOMEN. SECTION I. OF THE MUSCLES ON THE ANTERIOR AND LATERAL PARTS OF THE ABDOMEN. THE structures which compose the abdominal parietes, anteriorly and laterally, are the integuments, superficial fascia, muscles and tendons, a subjacent fibrous expansion, and a serous membrane ; nu- trient vessels and nerves ramify in and between these several laminae ; the integument is soft and smooth, but variable ; in women who have borne children it is found wrinkled, and the cuticle is marked in a peculiar reticular manner. Divide the integuments from the sternum to the pelvis, from the crest of each ilium to the umbilicus, also from this point upwards and outwards on either side over the cartilages of the ninth and tenth ribs, as high as midway between the axilla and the border of the thorax ; dissect off the flaps ; the subcutaneous cellular membrane will be found dense and strong, so as to have received the name of superficial fascia ; this may be removed, along with the integuments, from the superior and lateral parts of the abdomen, but inferiorly and anteriorly it may be suffered to remain for further examination, a knowledge of its structure and connexions being of practical impor- tance in the disease of hernia. The superficial fascia is continued from the surface of the thorax, over the abdominal muscles ; weak and thin above, it increases in density as it descends ; from the abdomen it extends 'on either side over Poupart's ligament to the thigh, which it invests, and in the centre over the organs of generation ; in the male a pro- cess of it passes round the spermatic cord on each side, descends into the scrotum, and is continuous with the fascia of the peringeum, and from the linea alba a thick portion runs to the dorsum of the penis, invests this organ, and serves as its superficial suspensory ligament and sheath ; the processes which enclose the testes are distinct and se- parate, and by their contact form the septum scroti. In the female it is loaded with fat in this situation, and descends into the labia, but these prolongations of the fascia in the male are always free from adipose deposit. As this fascia passes over Poupart's ligament, it is connected to it, through the medium of a thin, transparent, but strong DUBLIN DISSECTOR. 185 membrane, which ascends from the fascia lata of the thigh, and is soon lost on the abdominal muscles ; to this the superficial fascia is attached, so as to give the latter the appearance of adhering to Pou- part's ligament, alt hough it really is not so. This structure is sometimes called Scarpa's fascia, as that writer has described it under the name of the Aponeurosis of the fascia lata ;" we shall call it the deep fascia ofthe abdominal muscles ; it is always present, though very unequally developed in different subjects ; some of the inguinal glands separate this from the superficial fascia, so also does a femoral hernia, in its ascent on the surface of the abdomen ; though generally very thin, it imparts much strength and resistance to the tendon of the external oblique, as it adheres intimately to its fibres ; this fascia is also continued, as a very delicate lamina, over the spermatic cord, into the scrotum, this accounts for the fact, that when urinary effusions extend from the perinaaum over the abdomen, they do not pass towards the thigh, as this membrane forms a septum between it and the abdomen. About an inch below Poupart's ligament, in the groin, the superficial ad- heres intimately to the fascia lata ; in this situation the former is very thick and laminated, forming capsules for the inguinal lymphatic glands, and is connected to the fascia lata by vessels and nerves which perforate the latter in then- course to and from these glands, the superficial fascia, and integuments ; the fascia lata here also is very weak, and rather cellular, so that the superficial and deep fasciae are continuous or identified in this situation ; soon afterwards, however, they again become distinct. The superficial fascia is thinner along the sides than it is on the forepart of the abdomen ; its cutaneous sur- face is cellular, and closely connected to the integuments, particu- larly in the median line ; its posterior surface is more compact and smooth, and often appears to contain some elastic tissue, particularly about the lower part ofthe linea alba, not unlike the yellow fibrous ex- pansion which covers the abdomen of large quadrupeds ; several blood- vessels ramify between the skin and this membrane, three set on each side, viz., the external circumflex ilii, external epigastric, and external ptulic arteries; these all arise hi the groin, from the femoral artery, or from some of its branches, and ascend over Poupart's liga- ment ; the first ramifies towards the anterior spinous process of the ilium ; the second, which is the largest of the three, ascends towards the umbilicus ; and the third passes transversely towards the pubis ; these several arteries supply the integuments, and inosculate with the deep-seated vessels of the same name ; they are each accompanied by one or two veins, which are often found remarkably tortuous in preg- nancy or in ascites, and should be avoided in the operation of para- centesis of the abdomen; these superficial veins open into the saphe- na or femoral vein, below Poupart's ligament. The superficial fascia supports and connects the tleshy and tendinous fasciculi ofthe abdo- minal muscles ; it also possesses some power of resistance and a good deal of elasticity, which assists these muscles in the contraction ofthe pari les of the abdomen ; the superficial issometimes called "Camper's fascia." Remove the integuments and fascine from the surface of the 1 86 DUBLIN DISSECTOR. abdominal muscles, and continue the dissection as far back as within two or three inches of the spine. The dissection of these muscles re- quires much care and attention ; many of them are very thin, and in such close apposition, that the unpractised hand may have some dif- ficulty in raising their successive laminae ; some portions of these mus- cles also are often very indistinctly marked, particularly if the abdo- men have been long distended by dropsy, or in very weak, emaciated, or anasarcous subjects. In dissecting the external oblique muscle at its upper and anterior part, care must be taken not to raise its apo- neurosis or tendon, which is so thin, as it passes over the anterior part of the thorax, that it may be mistaken for condensed cellular membrane. In order to expose the external oblique muscle, make its fibres tense by putting a block under the loins, and dissect in a line nearly parallel to its fibres ; they are covered by a fine, closely- adhering, cellular coat, difficult to remove, if not already detached with the superficial fascia; to clean the posterior portion, the subject should be turned a little to the opposite side. The abdominal muscles are ten, or five pair, viz., obliqui externi, and interni, transversales, recti, and pyramidales ; the last are often wanting. Other muscles, however, are equally entitled to be called abdominal, viz., the diaphragm and the levator ani, quadratus lum- borum, psoas, and iliacus. These belong to the class of flat muscles, like the latissimus dorsi and serrati, the diaphragm and the levator ani ; they are placed in three laminae, one beneath the other, and it is important to observe that the fibres of one layer decussate those of the other two ; thus those of the external oblique descend obh'quely for- wards, those of the internal ascend obliquely forwards, and those of the transversales are circular, while in front those of the recti are ver- tical, and resemble longitudinal pillars opposed to the spine ; the three lateral muscxilar layers are closely connected together by snort cellu- lar tissue, with very little adeps, and their tendinous expansions an- teriorly are perfectly interlaced ; thus a very compact and resisting tissue is constructed out of thin and weak materials ; the fleshy fibres, though not actually interwoven, yet in effect resemble a platted tex- ture which prevents their divarication, and the consequent protrusion or hernia of any of the enclosed viscera. If the finger be introduced through an opening made in the side of the abdomen, even where the integuments have been removed, and an effort made to protrude it through the parietes, the resistance will be found very considerable, and such as, during life, must be fully competent to prevent a separa- tion of the fibres from any natural cause ; accordingly hernia occurs only in those situations where a natural weakness or deficiency exists, except in very rare instances, where the parietes have been injured by wound or disease, or much debilitated by long distention and absorp- tion of all adipose substance from the tendinous interstices; hence this, laminated and decussating arrangement is vastly superior to a simple circular muscle, the parallel fibres of which would be much more easy of separation, unless it possessed considerable thickness, which, how- IH'HLIX DISSECTOR. 187 ever, would have been not only inconvenient but even inferior to the present plan in power and variety of action ; the several lamina- an- mm- enabled to effect, not only a general and equable compression of Fig. 36.* * The muscles of the anterior aspect of the abdomen ; on the left side the su- perficial layer is seen, and on the right the deeper layer. 1. The inferior portion of the pectoralis major muscle. 2. The inferior indigitations of the serratus magnus muscle. 3. The external oblique muscle. 4. The anterior part of the crest of the ilium. 5. The aponeurosis of the external oblique passing in front of the rectus abdominis muscle. 6. The inferior border of the aponeurosis of the external oblique, forming what is termed the crural arch. 7. The intercolumnar bands, hi. The external abdominal ring. !). The superior and internal pillar ot the ring. in. Gimbcmaut's ligament. 11. Space beneath the crural arch or I'oupart's ligament, through which pass muscles, vessels, and nerves. 12. The xiphoid cartilage. 13. The umbilicus. 14. The pyramidalis muscle. 15. The m-tus muscle. 16. The internal oblique muscle. 17. The anterior layer of the tendon of the internal oblique', which passed in front of the rectus muscle, cut away close to its origin. 18. The posterior layer of the same tendon pawing be- hind the rectus muscle. 19. The internal surface of the aponeurosis of the ex- ternal oblique thrown downwards. -JO. The inferior fibres of the internal ob- lique. 188 DUBLIN DISSECTOR. the abdomen, but can also assist in a variety of most useful motions of the body with considerable effect. The fibres of some lamina; being oblique, and, therefore, longer than if they were circular, possess a greater degree of contractile force ; and as the fibres of one lamina have an origin, course, and insertion different from those of another, and as they can act either independently or in conjunction with the muscles on the same side, or with those on the opposite, which cor- respond in direction, and as both of these again may cooperate with, or antagonize other laminae, and may act or rest reciprocally, a compo- sition of forces is thus gained, from which must proceed an endless va- riety of results ; thus, while all concur in compressing the abdomen, the transversi and recti do so more directly; in expiration, in like manner, though all are concerned and press the viscera upwards and backwards, against the diaphragm, yet the obliqui are most efficient, as they also depress and adduct the ribs ; and again, while the entire group strengthen and support this division of the body, whose only fixed basis is the lum- bar spine, some can especially steady and balance it laterally, others bend it forwards, or to either side, and others, by rotating the lumbar ver - tebrrc, can move the whole body, as well as the pelvis and lower limbs, in almost all directions, so that no group of muscles can assist in a greater variety of pm-poses than those of the abdomen, although their name and their connexion Avith this cavity, may give rise to the im- pression, that their chief office is to assist in its functions, yet, most pro- bably, this is but their secondary use, it is rather as locomotive agents, as pelvi-thoracic muscles, they claim most attention ; in ordinary ex- piration, little more than their elasticity is required, though occasion- ally their full contractile power is called forth ; so in the function of the abdominal organs, the transverse or circular lamina, which has some resemblance to the involuntary muscles, is most influential, yet in occasional effoi'ts, such as vomiting, defalcation, and parturition, they all contribute to compress the viscera, and to contract the ca- vity. The abdominal parietes will be found chiefly tendinous poste- riorly and anteriorly, and fleshy on either side ; the anterior region is the most extensive, and the tendinous and fleshy strata which bind it are so arranged and proportioned, as to secure, to a certain extent, an equal degree of support, resistance, and contraction throughout, thus the external oblique is tendinous below, and fleshy above, the inter- nal is tendinous above and fleshy below, and the transverse is fleshy above and below, and tendinous in the centre ; the student may again peruse these preliminary observations after the dissection of these muscles. OBLIQUUS EXTERNUS, or DESCENDERS, broad, thin, and somewhat square, extends over the anterior and lateral parts of the abdomen, fleshy above and behind, tendinous before and below : some describe (unnecessarily in my opinion) the tendons of the oblique and trans- verse muscles as a distinct structure, and name it " anterior abdominal aponeurosis," as opposed to the posterior or lumbar, and composed of three, or, moi'e accurately, of four lamina? ; it arises by eight or nine DUBLIN DISSECTOR. 189 triangular fleshy slips (sometimes there are only seven) from the lower rill's and external surface of the eight or nine inferior ribs, at a little distance In mi their cartilages : the live superior indigitate with cor- responding portions of the serratus magnus ; and the three inferior with those of the latissimtis dorsi, by which they are a little over- lapped ; this serrated origin is in the form of a long curved line, the concavity upwards and backwards. The superior fibres are thin, aponeurotic, and weak, and pass horizontally inwards ; a tendinous and tleshy slip often connects this portion to the great pectoral muscle ; the middle are the longest, and descend obliquely forwards and inwards in the same line as the external intercostals ; the posterior are strong and fleshy, and descend almost vertically ; the superior and middle fibres end in a broad tendon, which commences at a little distance external to the linea semilunaris ; the outer border of this tendon extends in an irregularly concave line from the cartilage of the eighth rib, to the anterior superior spine of the ilium ; this line is external and differently curved to the linea semilunaris ; the tendon is continued over the fore- part of the abdomen, covers the rectus muscle, and is so broad inferiorly as, when taken with its fellow, to extend from one spine of the ilium to that of the opposite side ; it is very strong inferiorly, but so very thin above, where it covers the thoracic portion of the rectus, that the inex- perienced dissector often removes it along with the integument. The external oblique is inserted tendinous into the ensifonn cartilage, linea alba, pubis, Poupart's ligament (which is formed by a thickening and reflection or folding back of the lower fibres of this tendon), and into the anterior superior spinous process of the ilium, also tendinous and fleshy into the outer edge of the two anterior thirds of the crest of the ilium. Use, to depress and adduct the ribs, and compress the abdominal viscera, so as to assist in expiration, and hi the evacuation of the urine and faeces. When both muscles act, they can bend the trunk forwards ; if one only act, it will bend it to that side, audit may also rotate it to the opposite side ; if the thorax be the fixed point, they can bend forwards and upwards the pelvis, and each can rotate it towards its own side. This muscle is covered by the skin and superficial fascia, its posterior border is sometimes overlapped by the latissimus dorsi ; in some cases, however, these muscles do not meet, and a small part of the internal oblique is seen in the triangular space between them ; in this space a lumbar hernia has been known to have occurred ; in some forms of lumbar abscess, also, I have found the tumour to bulge towards the surface in this interval, which was then enlarged. On the dissected tendons of this pair of muscles, we may re- mark the following particulars : the linea alba and umbilicus, lineaa semilunaivs, linear transversa?, the external abdominal or inguinal rings, and Poupart's ligament on each side. The linea alba is a dense GgameotolU cord, extending from the ensifonn cartilage to the upper part of the symphisis pubis; it is formed by the intimate union and u-..s.-iug of the tendinous fibres of the two oblique and transverse muscles of opposite sides ; inferiorly, however, the fibres of the oppo- 190 DUBLIN DISSECTOR. site tendons only cross to be inserted into the opposite pubis, but do not unite or interlace ; its greatest breadth and thickness are at the umbilicus, from this to the pubis it decreases ; its superior portion is much broader than its inferior ; as the recti muscles are there so close together, it is reduced to a mere line, whereas above, particularly in corpulent persons, it is often half an inch broad ; in its infra-umbilical portion, where the decussating fibres of the tendons are less distinct, there is also a long, narrow, fibrous cord, which commences gradually a little below the umbilicus, and extends to the ligamentous covering of the pubes ; in very thin subjects this projecting cord can often be seen and felt through the skin ; as the linea alba is so narrow below, the abdomen is stronger in the middle region than above ; resistance and contraction being there more necessary, and here, therefore, hernia never occurs ; the integuments are more closely connected to this line, than they are at either side ; hence the more fat the subject, the more indented will the skin appear along it. About the centre of the linea alba, or a little below it, is the umbilicus ; this, in the foetus, was a foramen, through which were transmitted the umbilical vein from the mother, and the umbilical arteries and the urachus from the child ; before the integuments were removed, this spot appeared depressed, particularly if the subject have been very fat; it now projects, and seems formed of dense, cicatrized, cellular tissue, surrounded by, and connected to the adjacent tendinous fibres, and plugged up by the li- gamentous remains of the three blood-vessels which diverge from its posterior surface. Umbilical hernia occurs in the infant through this opening, but in the adult in its immediate vicinity ; posteriorly the peritoneum is in contact with the linea alba above, but below, the ura- chus, and occasionally the urinary bladder intervene. Several small openings exist in this line, through which bloodvessels pass and fatty masses protrude, and sometimes a small pouch of peritoneum ; the linea alba is increased in breadth, and becomes proportionately weak when the abdomen has long suffered disterition from any cause. The linea alba is regarded by some as the continuation of the ster- num, which, in some animals, is extended to the pubes ; it serves as a fixed point for the oblique and transverse muscles on either side, also as a resisting, but not an elastic ligament, to connect the thorax to the pelvis, and to support the former when bending the trunk back- wards, so as to resist or prevent too forcible extension of the spine. In the inferior part of this line the following operations may be perform- ed : puncturing the bladder in retention of urine ; paracentesis, or tapping of the abdomen, in ascites ; and the high operation for litho- tomy. The inferior fourth or fifth part of the linea alba is sometimes de- ficient, as also a portion of the muscles on each side, so that the urinary bladder is superficial, and constantly exposed; in such cases the anterior part of this viscus also is wanting, and therefore its ca- vity and the orifices of the ureters can be perceived during life. The Hnece semilunares extend from the tuberosity of the pubis on DUBLIN DISSKOTOK. 191 eaeh side upwards and outwards, about four inches from the linea alba, towards the cartilages of the eighth and ninth ribs ; they appear white, and somewhat depressed, and are formed by the tendons of the internal oblique, dividing at the edge of each rectus into two layers, to enclose tin's muscle in a sort of sheath ; the space enclosed between these two lines is oval, the larger end above ; it contains the two recti and the linea alba. In the living subject this line may be traced by taking a point midway between the umbilicus and the anterior su- perior spinous process of the ilium, and from it drawing one line towards the tuberosity, or spine of the pubis, and another towards the cartilage of the ninth rib. The operation of tapping ovarian dropsy should always be performed in this line ; and this situation is also se- lected by some as the best for performing paracentesis in cases of ascites. In this last-mentioned disease, however, this line is not exactly mid- way between the umbilicus and spine of the ilium, but half an inch nearer the latter, as the recti become flattened and expanded laterally. The lincce transversce are three or four on each side, they cross the rectus muscle from the linea alba to the linea semilunaris ; they are tendinous intersections of that muscle, particularly of its anterior part, which adhere so intimately to its sheath, as to give to the latter this indented appearance. They are much better marked in some than in others ; during life they are very distinct, when the abdominal mus- cles are in strong action ; one of these corresponds to the umbilicus, another to the ensiform cartilage, the third is midway between these ; if a fourth or fifth exist, they are inferior to the umbilicus and but feebly marked. These lines will be again noticed in the dissection of the rectus. Between the linea alba and semilunaris on each side many small holes are often to be observed in the tendon of the exter- nal oblique, these are only for the transmission of small vessels and nerves, are generally of a square form, and are much larger and more numerous in some than in others ; the fasciculi of the tendon also oc- casionally separate in a very variable manner, leaving triangular spaces between them, and in many situations they are intersected at various angles by other tendinous fibres. The external inguinal, or abdominal ring, also named by some anterior, and by others, inferior, transmitting, in the male, the spermatic cord and cremaster muscle, with its vessels and nerves, and in the female the round ligament of the uterus, is situated ex- ternal and superior to the pubis on either side. Tin's opening is of an oval or triangular form, the base is inferior and internal at the pubis, the apex is superior and external in the tendon, and formed by the separation of its fibres ; the sides are called the pillars of the ring, one of which is superior, internal, and anterior ; the other, or Poupart's ligament, is inferior, external, and posterior. The first, or superior pillar, is broad, and inserted into the symphysis and into the opposite pubis; some fibres are continuous with the fascia lata of the opposite thigh ; this pillar decussates with that of the opposite side, on the fort- part of the pubis, and both send fibres to the dorsum of the penis; the 192 DUBLIN DISSECTOR. inferior pillar is the internal or pubic end of Poupart's ligament ; the dimensions of this opening (improperly called a ring) are very va- riable, transversely they are about half an inch, and from an inch to an inch and a half from Avithin and from below, upwards and out- wards ; it is larger in the male than in the female. The apex of this opening is rounded by a series of fibres, which serve to connect the pillars to each other. These fibres arise from Poupart's ligament at a little distance from the spine of the ilium, pass in curved lines upwards and inwards across the upper part of the ring, and are lost superiorly on the surface of the tendon ; they serve, by preventing the separation of the sides of the ring, to protect this part of the abdomen against a protrusion of its contents ; the same order of fibres continue their at- tachments to the margins of the opening, and are prolonged inferiorly as a tine membrane on the spermatic cord ; in cases of long existing hernia this fascia becomes much developed, and forms one of the co- verings of the sac, and is found closely connected to the subjacent cre- master muscle. Anatomists have given to the whole of this structure the appropriate name of inter columnar fascia ; some, however, divide it into two, and name the superior fasciculated portion, " intercolum- nar bands, or fascia, 1 ' and the inferior membranous portion, " sperma- tic, or cremaster fascia ;" as, however, these two are so connected, and so allied in their use, we shall consider both as the intercolumnar fascia, only observing, that the superior portion is more distinctly ten- dinous and fasciculated, and the inferior more membranous ; if we se- parate this structure from the tendon and from the margins of the ring, commencing above, we can demonstrate the whole as one conti- nuous tissue extended indefinitely along the cord. It is this fascia, or these intercolumnal bands, that obscure this opening in many cases, and deprive it of that defined figure usually mentioned by writers, or delineated in plates. The tendon of the external oblique is alone con- cerned in the formation of the external abdominal ring, there being no corresponding deficiency in the internal oblique or transverse muscles ; the spermatic cord, or round ligament, must therefore have taken an oblique course to arrive at this opening ; this will be seen in the next stage of the dissection. Pouparfs, or Fallopius 1 ligament, or the/emora?, or crural arch^ is the inferior edge of the tendon of the external oblique, thickened and reflected upon itself from before backwards ; it is very strong, and when the lower extremity is extended, and the foot and toes everted, it appears very tense, and convex downwards and outwards ; it corres- ponds to the fold of the groin, separates, superficially, the abdomen from the thigh, and bounds anteriorly the large triangular or semi- lunar space, which the ilium and pubis complete posteriorly, and which space is occupied from without inwards by the iliac and psoas muscles, with the anterior crural nerve, the femoral artery and vein, internal to which are some cellular tissue, lymphatic vessels, and sometimes a lymphatic gland, also the origin of the pectinaeus muscle. If we consider it as a distinct ligament, it may be described DUBLIN DISSECTOR. 193 ;is having an attachment to, or as arising from the anterior superior spinous process of the ilium, thence it at first descends obliquely, and then proceeds forwards and inwards to the pubis, into which it is in- *erted by two attachments!, one anteriorly into the tuberosity or spine, and into the forepart of the bone beyond this process; the other, which <-t insists of the reflected fibres of the tendon, is narrow at first where it is folded in under that last described, and then expands, and is in- serted behind it, being continuous with it, partly into the spine, and principally into the prominent linea innominata of the pubis, or the commencement of the linea ileo-pectinea ; by means of this reflection backwards of these lower fibres, a sort of groove or channel is formed, which lodges the spermatic cord, supports it below, and separates it from the thigh ; the oblique tendon itself forms the front of this chan- nel ; this is named the spermatic, or inguinal channel, and will be more fully seen hereafter. The first, or iliac end of Poupart's liga- ment is broad and continuous above with the tendon of the oblique, and below with the fascia lata ; the anterior portion of the pubal end, or the second insertion, is distinct and round, and can be felt through the skin ; it lies behind the cord, and is connected to that portion of the fascia lata which covers the adductor muscles ; the posterior pubal attachment, or the third insertion, also called Gimbernaufs ligament, is broad and thin, and lies superior, posterior, and external to the former ; it may be seen by raising the cord out of the external ring, and everting Poupart's ligament a little ; it is of a triangular form, the apex is anterior, at the tuberosity, or spine of the pubis ; the base is external and posterior, somewhat crescentic, looking towards the femoral vessels ; to it some fibres from the outer, or ih'ac part of the fascia lata, are attached, so as to elongate it in this direction ; this third insertion of Poupart's ligament forms the internal boundary of the femoral ring, and is therefore concerned in the anatomy of femo- ral hernia, as will be seen hereafter. Poupart's ligament owes much of its strength to its connexion with the fascia lata of the thigh, as may be seen at present by merely flexing the limb ami inverting .the knee, the ligament then becomes relaxed, . as also the parietes of the ring ; hence this position is constantly resorted to, and often successfully, in attempting the reduction of inguinal hernia; it is this connexion to the fascia lata which gives it the arched, or curved appearance, convex towards the thigh, and which curve is straightened when the limb is bent and adducted ; it is also curved in another direction, concave forwards and convex backwards towards the ih'ac fossa ; this curva- ture depends on the intimate union between this ligament and the fascia iliaca and transversalis, which adds materially to the strength of this region ; and as the iliac fascia is also connected to that of the thigh, the position of the latter will alter or relax this curve as well as the former ; these curvatures are well marked during h'fe in the strong and muscular man: its attachment to the fascia transversalis and iliaca will be exposed in a future stage of the dissection. Poupart's ligament is of use in strengthening the inferior part of the abdomen, 194 DUBLIN DISSECTOR. and affording a fixed point of attachment to the deeper muscles and to the different aponeuroses ; it also protects the great femoral vessels and nerves in their passage from the abdomen to the thigh, and its third insertion partially fills up the internal portion of the crural arch. From this third insertion, and from the pubis, a band of fibres may be observed to pass upwards and inwards, behind the superior pillar of the ring, towards the linea alba ; these assume in general a triangular shape, and have received the name of the triangular ligament, or fascia ; the base is inferiorly at the linea ileo-pectinea ; the apex is superior and internal towards the linea alba, and is continuous with the external oblique tendon of the opposite side ; this fascia serves to protect the abdomen in this region ; this, though delineated by others, has been first particularly described in Colles' Surgical Anatomy, and is therefore commonly called " Colics' fascia ;" though described as a distinct structure, it really is only a continuation of the decussating fibres of the opposite tendons, as all through the linea alba above ; in fact, each of these ligaments is but a stronger portion of the external oblique tendon of the opposite side, and might be correctly described as arising from it in the linea alba, then expanding as it descends to its insertion in the opposite ileo-pectineal ridge ; it not only protects the abdomen behind the external ring, but it ties together all the sur- rounding textures, and confines them towards the linea alba ; it may be said to connect the superior pillar of one ring with the inferior pil- lar of the opposite ; it lies directly behind the cord, and is anterior, but inseparably united to the conjoined tendons of the internal oblique and transversalis, in front of the rectus ; its development as to strength and extent is very variable, m some it is so weak as scarcely to de- serve notice. Raise the external oblique, by dissecting off its serrated origins from the ribs, detach also its insertion from the crest of the ilium, and from the internal oblique muscle, cleaning at the same time the surface of the latter, throw the external oblique towards the opposite side, separating it as far forwards as its connexions will per- mit, that is, about half an inch internal to the linea semilunaris ; di- vide its tendon transversely from the spine of the ilium, towards the lower third of the rectus, about an inch above the external ring, thus preserving Poupart's ligament and the external ring for further exa- mination, in relation to the anatomy of hernia ; numerous small nerves and vessels are met with in this dissection ; several perforate the ten- don near the linea alba, and several also pass through its fleshy costal portions. When the external oblique is raised, we see the inferior ribs, the inferior intercostal muscles, the internal oblique, and the cremaster. OBLIQUUS INTERNUS, or ASCENDENS, is also situated at the ante- rior and lateral part of the abdomen, broader before than behind, and more fleshy below than above ; it arises tendinous, but soon becomes fleshy, from the fascia lumborum, from all the crest of the ilium, and from the two external thirds of the grooved, or abdominal surface of Poupart's ligament ; the fibres diverge in a radiated manner ; those DUBLIN mssl-XTOR. | <.).'> from the lumbar fascia and posterior part of the ilium ascend obliquely forwards ; those from the anterior part of the ilium pass transversely, and those from Poupart's ligament descend obliquely inwards ; the fibres continue fleshy further forward than those of the external oblique ; at the liuea semilunaris they end in a flat tendon, called by some the middle layer of the anterior abdominal aponeurosis ; at the edge of the rectus this divides into two layers to enclose this muscle ; the an- terior is united to the tendon of the external oblique, the posterior and thinner layer is joined to the tendon of the transversalis ; this does not extend so high as the anterior ; it commences on a level with the cartilage of the seventh or eighth rib only, so that above tin's point the rectus rests on the transverse muscle, which here continues fleshy for a little way internal to the liiiea semilunaris ; about midway between the umbilicus and the pubis, the tendon of the internal oblique does not divide, but the whole passes in front of the rectus, along with the tendon of the transversalis, to which it is closely con- nected; a little above the pubis these two tendons are intimately joined, and are called the conjoined tendons. The internal oblique is inserted, fleshy, into the cartilages of the four inferior ribs, the fibres meeting the internal intercostal muscles, to which they are parallel ; tendinous into the ensiform cartilage, and into that of the seventh and eighth ribs, also into the whole length of the linea alba ; the con- joined tendons are inserted into the symphisis and upper edge of the pubis, and, passing external to the rectus, are also inserted into the linea iunominata, where they are connected with Gimbernaut's ligament, and inseparably joined to the fascia transversalis ; while the inferior fleshy fibres pass anterior to the spermatic cord, these conjoined ten- dons lie posterior to it, also to the triangular ligament, and thus af- ford much security not only to that part of the abdomen behind the external abdominal ring, but also to the inguinal channel generally. The use of the internal oblique muscle is to assist the external oblique in expiration by depressing the ribs, and by compressing the abdomi- nal viscera, also to bend the trunk forwards, or to one side ; it can also rotate the trunk, but in doing so, it cooperates with the external oblique of the opposite side, with which it forms a sort of digastric muscle ; this muscle is covered by the external oblique and latissimus dorsi ; it lies on the transversalis muscle ; some small vessels ramify between them ; a small portion of the internal oblique is sometimes superficial, between the external oblique and latissimus dorsi, above the posterior part of the ilium ; the lower semilunar border is variable in strength and extent, it sometimes covers the cord as low as the ex- ternal ring ; along this inferior border we observe the following muscle : CREMASTER, or SUSPENSOUIUS TESTIS consists of a fasciculus of pale fleshy fibres, which arise from the internal surface of the external third of Poupart's ligament, and from the lower edge of the last de- scribed muscle ; a few fibres also sometimes proceed from the lower edge of the transversalis muscle ; it frequently, too, has a tendinous o 2 196 DUBLIN DISSECTOIt. attachment to the pubis, behind the external abdominal ring ; this fourth mentioned attachment, perhaps, rather deserves the name of insertion ; the fibres all pass downwards and forwards around the spermatic cord, but chiefly along its outer side, many of them in the form of arches reversed, or concave upwards ; they are inserted into the tunica vaginalis ; a few fibres are lost in the scrotum. Use, to support, compress, and raise the testicle and its vessels ; the origin of this muscle is covered by the tendon of the external oblique, and lies on the fascia transversalis ; a small but long nerve, a branch from one of the lumbar nerves, runs between its fibres ; the lower part of the muscle is superficial and very pale ; in cases of old hernia, the fibres of the cremaster are found greatly increased in thickness, and are often of a yellow colour ; and in that form of the disease called the oblique, or common inguinal hernia, this muscle always forms one of the coverings of the sac. The cremaster is absent in the female, or at least only rudimental. This muscle is probably formed incidentally ; the testis, in its descent to the scrotum, carrying before it the lower border of the internal oblique ; this will account for the arched direction of some of its fasciculi ; it is usually, but not always, much developed in cases of old inguinal, or scrotal hernia, also of hydrocele ; if an opportunity occur for examining it in the latter, it may be sometimes found, as described by different writers, to consist of two fasciculi, one descending from the inside of Poupart's ligament, having arisen from it and from the internal oblique, along the external and anterior sides of the cord, as low as the tunica vaginalis testis, on the surface of which it bends upwards, and becomes the other, or the ascending fasciculus, which rises along the inner and posterior sides of the cord, and is inserted into the pubis by tendinous or cellular tissue ; the continuity of these fasciculi is seldom satisfactorily seen ; during their course along the cord they are connected by fibrous loops, or arches, concave upwards. Raise off the internal oblique from the transversalis muscle ; com- mence above the anterior part of the crest of the ilium, where the muscles are separated by cellular membrane, and some branches of the circumflex ilii vessels, make one incision from the ilium towards the cartilage of the ninth rib, and another from the ilium towards the lower third of the linea semilunaris ; carefully dissect off the posterior part of the muscle, towards the spine, and the anterior towards the rectus ; this portion can be separated from the transversalis, a little beyond the linea semilunaris. TRANSVERSALIS, somewhat square, broader anteriorly than poste- riorly, arises tendinous from the fascia lumborum and the posterior part of the crest of the ilium, fleshy from the remaining anterior part of the crest, and from the iliac third of Poupart's ligament ; it also arises tendinous from the two last ribs, and by fleshy slips from the inner side of the five succeeding; these indigitate with the origins of the diaphragm ; all the fibres pass transversely forwards, except the most inferior, which are curved a little downwards ; they all end in a flat tendon, which, near the linea semilunaris, joins the posterior la- DUBLIN IHSSlXTOi;. 107 ininn of the internal oblique, and is inserted along with it into the whole length of the linea alba, into the upper edge of the pubis, and into the linea innoininata ; this tendon passes behind the rectus supe- riorly, but inferiorly, that is, about midway between the umbilicus and the pubis the conjoined tendons pass anterior to this muscle, and are inserted in the manner before mentioned. The transversalis ab- dominis is covered by the internal and external oblique ; it lies on the fascia transversalis and on the peritoneum. Use, to compress the ab- dominal viscera in the circular direction, and to assist in expiration ; it can also make tense the lumbar fascia, and approximate the ante- rior abdominal aponeurosis to it ; its fleshy fasciculi are weaker and paler than those of the obliqui ; they are frequently separated by in- terstices, in which the peritoneum and its cellule-fibrous covering ap- pear ; the fasciculi are connected to the latter by little slips, or pro- * A transverse section of the abdomen, to shew the relations of the abdominal muscles and their aponeuroses with each other, and with the neighbouring parts. 1. The upper surface of the body of the second lumbar vertebra. 2. A portion of the psoas magnus muscle. 3. A transverse section of the rectus abdominis muscle. 4. The cut edge of the external oblique muscle. 5. The internal ob- lique muscle. 6. The transversalis muscle. 7. The .latissimus dorsi muscle. 8. The quadratus lumbprum muscle. 9. The mass of muscle common to the sacro-lumbalis and longissimus dorsi muscles. 10. The aponeurosis of the inter- nal oblique uniting itself to that of the trimsversalis muscle. 11. The posterior aponeurosis of the transversalis muscle dividing into three laminae. 12. The an- terior lamina of the aponeurosis of the transversalis passing in front of the qua- dratus lumborum to its insertion at the root of the transverse process of the ver- tebra. 1-3. The middle layer of the same aponeurosis, passing behind the qua- dratus lumborum and in front of the lumbar mass of muscles, to be inserted into the apex of the transverse process. 14. The posterior layer of the same aponeu- rosis passing behind the lumbar mass of muscles to be inserted into the extremity of the spinous process of the lumbar vertebrae. 15. The aponeurosis of the ex- ternal oblique terminating in the linea alba. 16. The anterior aponeurosis of the internal oblique separating into two lavers at the external border of the rectus muscle. 17. The reunion of the same lavers at the linea alba. 198 DUBLIN DISSECTOR. cesses, which are very distinct, and which closely attach this muscle on each side to the lining membrane of the abdomen ; it is a perfect constrictor of this cavity, and appears a sort of transition muscle be- tween the voluntary or parietal muscles external to it, and the invo- luntary or visceral muscles within. This muscle is tendinous before and behind, fleshy in the middle, also above and below, contrary to the two oblique muscles ; the posterior tendon is described by some, as dividing into three layers, which are, in fact, the three sheets, or leaves, of the lumbar fascia ; the posterior, very strong, is continuous with the fascia lumborum ; the middle, thinner and weaker, is attached to the transverse processes of the lumbar vertebrae ; and is separated from the former by the lumbar muscles ; and the anterior lamina, which is the weakest, is expanded over the quadratus lumborum, and the inferior part of the diaphragm, and is connected to the sides of the bodies of the lumbar vertebrae. The anterior inferior edge of the transversalis is in some degree confounded with that of the internal oblique, particularly at their origin from Poupart's ligament ; its fleshy border, however, very seldom descends so low as that muscle ; it crosses the cord or round ligament, j ust as either of these is about to pass through the internal or superior abdominal ring in the fascia transversalis ; the internal oblique is on a level with the lower border of this opening, and therefore conceals it ; the transversalis is parallel to its upper, and only partially covers it, and is often connected to the cord at this point, in a manner we shall consider presently. The con- joined tendons generally admit of partial separation near the pubis and behind the external ring ; the tendon of the transversalis being broader and stronger than that of the oblique, its fibres may be ob- served to expand and curve downwards and outwards behind the cord, nearly as far as opposite the inner margin of the internal ring ; this expansion is inserted, along with the oblique tendon, into Gim- bernaut's ligament, and more externally into Poupart's ligament be- hind the cord, its transverse extent being from the rectus internally to a point externally below the internal ring ; the lower muscular fibres will be found to pass obliquely inwards above and before the cord, and then bending downwards, and a little outwards, end in this ten- dinous expansion behind it, occasionally some fleshy fibres descend on or among the tendinous, and are inserted into the pubis or into Pou- part's ligament ; to the posterior surface of this tendinous expansion the fascia transversalis is intimately attached ; this peculiar arrange- ment of the lower border of this muscle, its fleshy fibres being above and in front of the cord, and its tendinous expansion curving below and behind it, has been particularly noticed by Sir A. Cooper, in his paper on the descent of the testis ; it appears designed to enable this muscle, when in action, to close or contract this opening, as also the inguinal canal, and thereby protect this part of the abdomen against protrusion of its contents. When we proceed to raise the lower fleshy border of the transversalis, we shall often find a peculiar attachment between it and the cord, as the latter is about to pass through the DUBLIN DISSECTOR. 199 internal ring ; this attachment, according to Mr. Guthrie,* depends on a few fibres of the muscle passing behind the cord at this point, these then, descending inwards, join the tendon of the muscle in its course to Poupart's ligament, so that the cord actually splits the lower border of the transversalis, a small fasciculus only passing behind or between it and the fascia, and rounded so as to support it ; thus a sort of transverse elliptical opening exists near the inferior border of this muscle, through which the cord passes ; this posterior fasciculus is not in all cases fleshy, but only tendinous or cellule-fibrous, con- nected, however, externally to the muscle, and internally to its ten- dinous expansion ; this structure is of considerable importance, it fortifies the abdomen against hernia, and when this has occurred, it must not only exercise much influence on the tumour, but it also suggests practical hints for its treatment ; this slit Mr. Guthrie proposes to call the internal abdominal ring, instead of that passage through the trans- verse fascia which is directly behind it ; it does not, however, appear to me advisable to adopt this innovation as to name, although we may concur with much of the description. Since the publication of Mr. Guthrie's memoir, I have paid much attention to the anatomy of this part, and I freely admit that in many instances I have found his statement perfectly correct ; not long since I demonstrated the cord passing through the lower border of this muscle, and surrounded by an almost perfect sphincter. I have lately also seen the same forma- tion in a foetus, and I have also observed the round ligament to pass through it, and to have muscular fibres prolonged upon it, which must have had the power, not only of compressing, but also of retracting this substance. I have also sometimes seen a distinct muscular fascicu- lus arising by a tendon from Poupart's ligament near the ilium, thence passing behind the cord to join the common insertion ; and I believe that this, or some such connexion between the cord and the transver- salis muscle would be more frequently detected, if we dissected the parts from within outwards, that is, first draw down the flap of the abdo- minal parietes, then raise off the peritoneum, and separate and exa- mine the several laminae of fasciae, muscles, and tendons towards the skin. I must, however, observe, that the structure just described is by no means uniform ; I have often carefully looked for it and in vain. I have, no doubt, frequently noticed a feeble cellulo-fibrous band passing behind the cord, and connected to the muscle and its tendon, by its extremities ; it may have been that this band had been ori- ginally muscular, and had degenerated in course of time ; in other cases this also has been wanting, and the lower border of the muscle has had no connexion whatever, direct or indirect, with the cord, and has not even descended to within an eighth of an inch of the internal ring ; experience induces me to affirm, that not only is this particular structure extremely variable, but many other parts also in this region, so that the student will seldom find the appearances presented on dis- * Guthrie on inguinal and femoral Hernia. 200 DUBLIN DISSECTOB. section to correspond exactly with the descriptions or delineations of any author, he should, therefore, make frequent examinations of this region for himself, as in that way only can he hope to obtain an accu- rate and satisfactory knowledge of this intricate but important sub- ject. Replace the oblique muscles, divide their tendons along the side of the linea alba, and dissect them off the rectus towards the linea semilunaris ; this anterior part of the sheath adheres so closely to the lineae transverse, that it is difficult to separate it from them. RECTUS, long and flat, broad and thin above, thick, strong, and narrow below, arises by a flat tendon, which is sometimes double, from the upper and anterior part of the pubis, between the spine and symphysis ; the external tendon is the larger ; it also sometimes receives fibres from the linea alba, which decussate with the opposite; the size and extent of its origin depend on the presence or absence of the pyra- midal muscles ; it ascends parallel to its fellow, becomes broad but thin above the umbilicus, and is inserted into the anterior part of the thorax by three fasciculi, the internal one of which is fixed to the car- tilage of the seventh rib, and costo-xiphoid ligament ; the middle, longer and thinner, to the cartilage of the sixth rib, and the external, still broader and thinner, to the cartilage of the fifth rib ; occasionally a small fasciculus is attached to the ensiform cartilage, and it is by no means uncommon to find a slip continued into the great pectoral, more rarely this passes over it, and extends to the clavicle, or to the clavicular portion of the sterno-mastoid muscle. Use, to bend the chest towards the pelvis, or to raise the latter towards the chest, also to compress the abdomen. The rectus is covered superiorly by the great pectoral, in the middle by the tendon of the external, and the anterior layer of that of the internal oblique muscle, and inferiorly by the external oblique, and the conjoined tendons of the internal oblique and transversalis, also by the pyramidalis ; the fascia transversalis is closely attached to the outer edge of its inferior portion. These mus- cles are much nearer to each other below than above ; they are each enclosed in a distinct sheath, which consists, anteriorly, of the tendon of the external oblique, and the anterior lamina of the internal oblique, posteriorly of the posterior layer of the internal oblique, and the ten- don of the transversalis. The sheath commences at the edge of the thorax, and terminates midway between the umbilicus and the pubis ; below which all the tendons pass anterior to this muscle. If this part of the rectus be divided, the deficiency in the back of the sheath will be obvious, as it generally terminates abruptly by a lunated edge; in some cases, however, it ends gradually in a thin tendinous expan- sion ; the epigastric vessels ascend within this sheath, on the posterior surface of the muscle ; the posterior wall of the sheath is also deficient siiperiorly on the thorax ; the internal mammary vessels enter it above its superior posterior border, as the epigastric do below its inferior. The sheath of the rectus serves to confine this muscle in its proper place, and to prevent it, when contracted, from injuring the abdominal viscera immediately behind it ; it also strengthens the parietes of the DUBLIN DISSKCTOK. 201 abdomen, and prevents the more frequent occurrence of hernia ; the deficiency in the back part of the sheath below may permit the ab- dominal muscles to exert more direct influence on the uterus, also on the urinary bladder when distended. In wounds of the parietes in this situation, with protrusion of the intestines or omenta, we should take care, in returning them into the cavity, that they do not slip into this sheath behind the muscle : the linger should, therefore, follow the last portion, and by moving it laterally, the true course will be easily ascertained. The rectus is intersected by three or four irregular, or zigzag, transverse, tendinous lines ; one of these linea; transversce is always to be found opposite the umbilicus, a second midway between this and the xiphoid cartilage, opposite to which a third is always'placed ; if a fourth exist, it will be found below the umbilicus; these inter- sections are not complete ; they are generally deficient on the back part of the muscle, hence the posterior fasciculi are longer than the anterior ; the anterior part of the sheath, and the linea alba, adhere intimately to each of them ; by means of these lines the rectus is con- stituted a sort of poligastric muscle ; the fibres of the first muscle arising from the anterior surface of the thorax, and inserted into the first intersection, or linea transversa ; the second arising from this point, is inserted into the second intersection, and so on in succession ; al- though the posterior fibres are not thus regularly interrupted, yet they do not continue the entire length of the muscle ; some of the an- terior fibres also occasionally pass over one intersection without being entangled in it ; this structure enables the rectus to act in distinct or separate portions, so as to compress different parts of the abdomen in succession, each section having a distinct nerve ; it also imparts con- siderable strength and resistance to the anterior abdominal aponeu- rosis, and to the linea alba, while, moreover, it associates in a most important manner, the recti with the lateral muscles, so as to enable them, not only to cooperate, but reciprocally to balance and moderate each other ; when the recti contract, the viscera are pushed back- wards and pressed out laterally, the obliqui then support and com- press them ; and when the latter act, and the viscera are thereby pro- truded forwards, the recti in their turn resist and support them, and one object of the interruptions in these muscles would appear to be, to enable the recti to act the better as moderators of particular sec- tions of the obliqui, and vice versa in respect to the latter upon the former ; by means too of this association or connexion between the lateral muscles and these transverse partitions, the influence of the recti and obliqui must be greatly and remotely extended ; were the recti merely attached to the sternum and pubis, they could only com- press the viscera and approximate their own attachments by flexing the spine, but as the internal oblique are intimately united to their tendinous sheaths and intersections, the recti can now act through these oblique muscles on the whole of the anterior and lateral margins of the pelvis ; this apparently complex structure then in the recti, is clearly of essential sen-ice in the functions of all the abdominal muscles. 202 DUBLIN DISSECTOR. Meckel maintains that these intersections are " incontestibly" but in- complete repetitions of ribs in the abdominal walls, as the linea alba is analogous to the prolonged sternum of the crocodile, and the two oblique muscles to the two laminae of intercostals, and the transversa- les to the triangulares sterni. The doctrine of analogy is, no doubt, highly interesting, and often most useful as being explanatory, but when a special structure exists for an obvious special purpose, there appears but little advantage in resorting to it. Anterior to the origin of the rectus is the following small muscle. PYRAMIDALIS is sometimes absent, it arises broad and fleshy from the symphysis pubis, and from the upper edge of the bone external to it ; the internal fibres ascend vertically, the external obliquely in- wards, and are inserted narrow and tendinous into the linea alba, midway between the umbilicus and pubis. Use, it assists the rec- tus, and makes tense the h'nea alba ; it is covered by the tendon of the external oblique, by the triangular ligament, and the con- joined tendons ; it appears in some cases to be enclosed in a splitting of the latter ; bony processes or ridges sometimes rise from the upper border of the pubes, in the line of these muscles, denoting a remote analogy to the supra-pubal bones and muscles in the marsupiata. The group of muscles now described belongs to the class of volun- tary muscles, with certain peculiarities ; as locomotive agents, the will can excite and control them on both sides together, or on either singly ; also in the acts of expiration and vomiting, defecation and parturition, the will can influence them, although in each of these they occasionally act without even the consciousness of the indivi- dual, and thus afford remarkable examples of sympathy with different organs, the lungs and larynx, the stomach and intestines, the uterus and the bladder, sympathies which cannot be explained by any direct nervous communication, and must, therefore, depend on the excito- motor power of the nervous system. The combined actions of these muscles must be to diminish the cavity and to compress the viscera of the abdomen ; in painful conditions of the peritoneum or its contents, we perceive the efforts that are made to keep these muscles in a re- laxed state by bending the thighs, and approximating the pubes to the sternum, in this position. I think I have sometimes observed that a gentle action of the recti was maintained, as if to bear off' all ante- rior weight or pressure from the tender parts within. By the simul- taneous action of these muscles, the viscera are pressed backwards against the unyielding spine, upwards against the diaphragm which is thereby raised in an arched manner on either side, where it chiefly ad- mits of this change, against the lungs, from which the air is expelled, and expiration occurs ; also downwards into the pelvis, thereby press- ing against the levator ani (the counterpart of the diaphragm), this then protrudes towards the perinaeum, which becomes somewhat con- vex, and if the sphincters now assent, defalcation will result ; thus the transverse and antero-posterior diameters are lessened, while the ver- tical axis of the abdomen is increased, and, if the contraction be mo- 203 derate, the parts within suffer but little compression ; should the diaphragm, however, and levator ani contract at the same time, as they always do when any violent muscular effort or strain is made, then the cavity is contracted in all directions, the viscera are sub- jected to strong and general compression, and then it is that some weak spot in the parietes gives way, and a hernia protrudes : the sur- gical anatomy of the parts concerned in this disease shall next engage our attention. Dissect off the transversalis muscle in a direction from the ilium towards the linea semilunaris, and. the fascia transversalis will be ex- posed covering the peritonaeum ; this fascia is connected on either side to the internal h'p of the ilium and to the whole length of Poupart's ligament, as far as the pubis ; thence it extends all over the abdomen, lining the transverse muscle, covering the peritoneum, and presenting different appearances and degrees of strength hi different situations, aponeurotic in some, cellular in others. It consists, at least inferiorly, of two laminae ; the external or superficial is fibrous, and distinct, and strong in each inguinal region ; it lines the muscle and is closely united to its fasciculi ; this is the true fascia transversalis : the epigas- tric vessels intervene between it and the deep, or cellular layer, which is attached to the peritoneum, and is, in fact, its subserous tissue ; in the superior and lateral regions of the abdomen the fibrous tissue is scarcely discernible, and the whole fascia appears little more than fine connecting cellular tissue ; but in each inguinal region the fibrous layer is distinctly aponeurotic, and the deep cellular layer, or tissue, is thick and abundant, allowing the peritoneum to be freely separated from the iliac and inguinal fossae, filling up the angular insterstices behind Poupart's ligament, also partially closing the femoral ring, and then extending into the pelvis. It is not, perhaps, critically cor- rect to consider the subserous tissue as a layer of transverse fascia, although it may be convenient to do so in anatomical description ; this cellular lamina cannot be seen at present, but will be again al- luded to in connexion with the crural arch and femoral hernia : from Poupart's and Gimbernaut's ligament the fascia transversalis is pro- longed upwards, even to the diaphragm, with the cellular coating of which it is continuous ; externally, to the psoas muscle and to the spine, internally to the rectus ; to the border of which it adheres so closely as to appear to end abruptly ; a thin lamina, however, ex- tends behind to join that from the other side ; immediately above the pubis this close connexion to the edge of the rectus is very marked ; it here also plainly separates into two laminae, one, strong and tense, ad- heres to the outer and anterior border of the muscle; the other, thin and weak, passes posterior to it : between the pubis and the crest of the ilium, and for about an inch and a half above the crural arch, this fascia is generally aponeurotic and firm, and claims particular atten- tion ; immediately external to the rectus it is inserted into the h'nea innominata of the pubis in common with Gimbernaut's ligament, but on a plane posterior to it ; tracing it outwards we observe it advancing 204 DUBLIN DISSECTOR. a little forwards, and attached to the inner border of Poupart's liga- ment through its whole length, as far as the spine of the ilium, and beyond this to the crest of that bone ; its connexion to the ligament appears very intimate, and accounts for some writers describing the fascia, as " arising from the reflected border of the crural arch ;" this is not critically correct, for dissection will shew a portion of it descending into the thigh behind this arch, through a space about two Fig. 38.* * The inguinal region in the male. 1. The symphysis pubis. 2. The anterior superior spinous process of the ilium. 3. 3. The external oblique muscles. 4. The linea alba. 5. 5. The linea semilunaris. 6. 6. The external abdominal rings. 7. The origin of the intercolumnar fibres. 8. Poupart's ligament extending from 2. to !). The lower pillar of the abdominal ring. 10. The iliac portion of the fascia lata of the thigh. 11. The saphena vein. 12. The pubic portion of the fascia lata. 13. The tendon of the external oblique cut open, to shew the parts that are situated behind it. 14. The internal oblique muscle, its lower edge is raised and turned up. 15. The transversalis muscle, its lower edge is also raised and turned up. 16. The fascia transversalis. 17. The internal abdominal ring, the fascia is strong external and inferior to it, but weak on the pubal side, being there strengthened by the transversalis tendon. 18. The internal epigas- tric artery and vein, situated behind the fascia transversalis, at first on the inner side, and afterwards behind the spermatic cord. 1!. 19. The spermatic cord de- scending from the internal abdominal ring, along the inguinal canal, through the external abdominal ring, and down to the testicle. IH'HLIX DISSECTOK. 205 inches broad, in front of the crural ring, and of the femoral vessels ; tliis process is named the " anterior sheath" of these vessels, and it can be traced as low as the junction of the saphena with the femoral vein, where it is lost in the general cellular sheath ; for the present this process requires no further notice; external to the iliac or femoral ar- tery the fascia transversalis is most intimately attached to Poupart's ligament as far as the spine of the ilium ; and through this extent it is also continuous posteriorly with the fascia iliaca, which is a strong membrane covering the psoas and iliac muscles, and will be more par- ticularly noticed hereafter ; a dense white line marks the amalgama- tion between these three structures, viz. : the transverse and iliac fascia?, with Poupart's ligament ; this line extends in a gentle curve from the femoral artery to the crest of the ilium ; enclosed in its apo- neurotic or seam-like texture are the internal circumflex ilii artery and veins, these vessels give additional firmness to this line, which acts as a tense connecting band, strengthening Poupart's ligament, and tying it clown posteriorly close to the iliac muscle, so as to close com- pletely that portion of the crural arch external to the artery, and effectually secure it against any protrusion from the abdomen. From Poupart's ligament to a short distance above the level of the lower border of the transverse muscle, this fascia is usually firm and resist- ing, and therefore it materially serves to strengthen the wall of the abdomen, and to compensate for the deficiency and weakness of the internal oblique and transverse muscles, which do not descend so low as the crural arch through the whole of this extent ; this portion of the fascia is behind the spennatic cord ; it is covered immediately be- hind the external ring by the conjoined tendons, and more externally by the folded fibres, and by the tendinous expansion of the transver- salis muscle, and still more externally, for a short distance, the cord lies upon it, until it arrives at the superior, or internal ring, where occasionally a fasciculus of the transverse muscle intervenes; the sper- matic cord, or the round ligament, always perforates this fascia about half or three quarters of an inch above Poupart's ligament, and about an inch and a half or two inches from the tuberosity of the pubis; this perforation is called the internal, or posterior abdominal ring, and is situated about midway between the spine of the ilium and the symphisis pubis ; it is not a distinct opening, for the fascia is pro- longed in a tubular form for an indefinite distance, as one of the cover- ings of the cord, and, though fine, it can be traced even to the tunica \ a-inalis ; this process is named the infundibuliform fascia ; by gently drawing the cord towards the external ring it becomes very evident, and if this be now divided with a few circular touches of the knife, and pushed a little upwards, the internal, or superior, or poste- rior abdominal ring Avill become distinct ; through tin's opening ob- lique inguinal hernia occurs, audit is in this situation that the neck of the sac suffers strangulation ; about the eighth of an inch to its inner or pubal margin is placed the epigastric artery, usually with a vein on cither side ; these vessels are posterior to the fascia transversalis but 20G DUBLIN DISSECTOR. can generally be distinguished through it ; a small hole may be made in it to expose them more distinctly ; they may be considered practi- cally, though not critically so, as forming the internal, or pubal boundary of the ring, while the transverse muscle borders it supe- riorly and externally ; projecting through this opening we perceive the peritoneum covered by its subserous tissue, or the cellular layer of the fascia transversalis ; from this projection, or bulging of the perito- neum (which will be more evident if we make gentle pressure on the abdomen above), a fine smooth fibrous process extends down along the cord ; this is the remains of the tubular process of peritoneum which, in the foetus, led from the abdomen to the scrotum, and behind which, and enveloped by it, the testicle and cord were guided from their ori- ginal situation in the abdomen to their final destination in the scro- tum ; this tube was at first a serous canal, communicating above with the cavity of the peritoneum, and below with that of the tunica vagi- nah's ; shortly after the descent of the testis this tube becomes closed, its sides adhere, and in process of tune it loses all its original serous character ; it is named the tunica vaginalis of the cord, as it serves to enclose, in a sort of sheath, all its component parts, except the cremas- ter muscle, which is superficial to it. Inguinal hernia in the adult descends in front of this tissue, between it and the superadded cover- ings of the cord ; in infancy, however, this tube is not always closed sufficiently early or completely, and then an inguinal hernia may de- scend within it down to the testis, such form of hernia is named conge- nital inguinal hernia. The interval between the internal and external abdominal rings is traversed hi man by the spermatic cord, and is named the inguinal or spermatic canal, to the anatomy of which the student should particularly attend, as the disease of inguinal hernia is situated here, in the treatment of which a correct knowledge of this region will be required. The spermatic or inguinal canal represents a sort of oblique, narrow groove, or gutter, the concave surface below, one wall, or side, in front, another behind, and, superiorly, a mere muscular in- terstice; it commences at the internal ring, and leads obliquely downwards, forwards, and inwards to the external, or inferior ring, where it terminates ; this passage is bounded anteriorly by the skin and the two laminae of the superficial fascia, by the tendon of the ex- ternal oblique, and by the inferior fleshy margin of the internal ob- lique muscle ; posteriorly, and from the internal to the external ring, by the transversalis fascia, covered sometimes by a few fibres of the trans- verse muscle, which are behind the cord, and next by the folded fibres and expanded tendon of this muscle, and lastly, by the conjoined tendons covered by the triangular ligament ; inferiorly by the broad, grooved, or concave surface of Poupart's ligament and its reflected fibres proceeding to form its third insertion, or Gimbernaut's ligament, superiorly this space is closed by the apposition of its opposite sides ; or rather it is occupied by the fleshy margin of the transverse muscle : as this muscle seldom descends below the upper border of the internal ring, it cannot be correctly said to form auy of the anterior boundary 1M-RLIX DISSECTOR. 207 of Uiis space, though occasionally it has been so stated ; not so, how- ever, with the internal oblique, the fleshy margin of which is always anterior to this ring, and to the cord for some distance below it, whilst its tendon is posterior to it opposite the external ring; it is, perhaps, on this account, that some writers omit (I think incorrectly) this muscle from among the anterior boundaries of this canal. On the posterior, or abdominal wall of this ingui- nal channel we perceive a triangular depression, defined internally by the edge of the rectus, externally by the epigastric vessels, inferiorlv by Poupart's ligament ; this depression is bounded poste- riorly by the conjoined tendons and the triangular ligament in its two inner thirds, and in its outer third by the expansion of the transversa- lis tendon and fascia ; the lower part of this depression is opposite the external ring, and through this, direct or ventro- inguinal hernia oc- curs. In the male the spermatic cord and cremaster muscle, and in the female the round ligament of the womb, pass through this canal, the obliquity, or valve-like structure of which serves to protect the abdomen against a protrusion of its contents. Inguinal hernia occurs more frequently in the male than in the female sex, in consequence of the spermatic cord and the inguinal rings in man being larger than the ligamentum teres, or these openings in the female ; in the infant the inguinal canal is shorter, less oblique, the rings are more nearly opposite, owing to the narrow pelvis, and to the crural arch being short, hence if the same exciting causes were present at this age, hernia would be more frequent in its occurrence than in the adult ; I have, however, observed that the parietes are more muscular. Inguinal hernia is either oblique or direct. Oblique inguinal her- nia is the more common form ; hi this case the peritoneum, or hernial sac, with its contents, protrude through the internal ring along the anterior part of the spermatic vessels, carrying before it the surrounding cellular tissue and a prolongation of the fascia transversalis from the edges of the opening ; the first is called the fascia propria of inguinal hernia, and the second the fascia infundibuliform. When the tumour has arrived at the lower edge of the internal oblique it insinuates it- self between the cremaster muscle and the vessels of the cord, along which it descends to the external ring, where it is in general delayed for some time ; the form of this opening and the inter-columnar fascia preventing its free passage through it ; as the sac, however, descends towards the scrotum, these inter- columnar fibres become closely united to the cremaster, and are gradually elongated on the surface of the tumour. If oblique inguinal hernia which has passed the external ring be carefully dissected, it will be found covered by the following parts ; beneath the integuments is the superficial fascia, in general much thickened and divisible into two or more lamuiae, next is the in- ter-columnar fascia supporting the tumour and attaching it towards the external ring; beneath this, and generally intimately united to it, is tin- rreinaster muscle, the fibres of which are often, but not uni- formly, found considerably thickened and strengthened ; these two last 208 DUBLIN DISSECTOR. mentioned structures frequently form one capsule to the tumour; deeper than this is the infundibulifonn process of the fascia transver- salis, derived from the margins of the internal ring, and subjacent to this is the cellular, or internal layer of the fascia transversalis, thus immediately covers the hernial sac, or the peritoneum, and may be named its fascia propria ; beneath this the hernial sac, or the pe- ritoneum, will be found, which also, in cases of old hemia, will be consi- derably thickened ; on opening the hernial sac, its contents, either omenttun or intestine, will be seen ; these coverings are found to be Fig. 39.* * This plate represents, on the left side, a small oblique inguinal hernia, mak- ing its appearance at the internal ring, on the outer side of the internal epigas- tric artery ; and on the right side a scrotal hernia, with its coverings displayed by dissection. (After Sir A. Cooper.) 1. The anterior superior spirious process of the ilium. 2. The tendon of the external oblique muscle reflected, to shew the inguinal canal. 3. The external, or superficial abdominal ring. 4. Poupart's ligament. 5. The internal oblique muscle, its lower margin is turned upwards to expose the hernial sac. G. The lower edge of the transversalis muscle. 7. The fascia transversalis. 8. The femoral artery. 9. The femoral vein. 10. A hernia appearing at the internal abdominal ring, midway between the anterior superior spine of the ilium and the symphysis pubis ; a small portion of the internal epi- gastric arteiy is seen on its inner side. 11. 11. The spermatic cord seen emerg- ing from the internal abdominal ring behind the hernia, and taking its course through the external ring into the scrotum. 12. The rectus muscle, 13. 13. The integuments reflected, to shew the coverings of the hernia after it has reached the scrotum. 14. The fascia superficialis coining from the external abdominal ring, and forming the superficial investment of the hernia ; at its upper part the transverse fibres of the external ring are seen. 15. The cremaster muscle thickened ,- it is seen descending under the margin of the external ring, and is lost upon the tunica vaginalis at 17. 16. The hernial sac covered by the fascia propria. 17. The testicle. DUBLIN DISSECTOR. 209 extremely variable, being sometimes easy of separation, at others, con- densed and united by adhesive inflammation into one homogeneous covering, in wliieh it is impossible to recognize the different tissues and lamina 1 we have enumerated. The student should next attend to the situation of the epigastric vessels and their relation to the parts concerned in oblique inguinal hernia ; these vessels are placed behind the fascia transversalis between it and the peritonaeum, or rather be- tween the lihrous and cellular laminae of the fascia, and in general can be discerned through the latter; if not, a little dissection, as has been remarked before, will render them apparent ; two veins usually accom- pany the artery, one on either side ; sometimes there is but one epigas- tric vein, and that is on the pubal, or inner side of the artery. The epigastric artery arises from the external iliac, near Poupart's liga- ment ; it first descends a little forwards and inwards, then ascends towards the rectus muscle, immediately behind the fascia transversalis, and very near to the inner, or pubal side of the internal abdominal ring ; in this course it forms the external boundary of that triangular depression on the posterior surface of the inguinal channel, of which the rectus is the inner border, and Poupart's ligament the base ; this surface, as was mentioned before, is bounded posteriorly in its two in- ternal thirds by the tendons of the oblique and transverse muscles, and in its external third, by the fascia transversalis ; it is through some part of this space, internal to this artery, that direct inguinal hernia occurs ; nearly parallel to this vessel is the ligamentous cord- like remains of the umbilical or hypogastric artery, proceeding towards the umbilicus : this cannot be distinctly seen at present ; it will be found hereafter, that this substance, by projecting inwards, or towards tlie cavity of the abdomen, causes the peritoneum to bulge on either side of it into two pouches, called the internal and external inguinal pouches ; these are separated by this projecting cord, and when the viscera are forced, by the violent contraction of all the parietal muscles, into these pouches, there is a strong tendency to protrude them still more, and thus this conformation is very generally believed to favour the production of hernia ; the internal abdominal ring corresponds to the lower part of the external inguinal pouch ; and the triangular sur- face just spoken of, behind the external ring, corresponds to the in- ternal inguinal pouch. The obliterated hypogastric artery is not always parallel to the epigastric, but is sometimes a little internal to it, in which ease a small pouch, or fossa of peritoneum, will exist be- tween these, cut off by the epigastric artery from the large external inguinal pouch ; this fact will be shewn directly to possess some ana- tomical interest, as well as practical importance. In oblique inguinal hernia, particularly if of long standing, the neck of the sac is nearly in contaet with the epigastric vessels, which thus bound it on its inter- nal side : hence the rule of practice in performing the operation for the relief of strangulated oblique inguinal hernia, Avhen the stricture is seated in the neck of the sac, is, to direct the edge of the knife, or bis- toury, upwards, or upwards and outwards. Direct, or ventro-inguinal 210 DUBLIN DIS8EOTOK. hernia protrudes directly through the external ring, without descend- ing along the spermatic channel The occurrence of this species is in a great degree guarded against by the fascia transversalis, and by the expansion of the tendon of the transverse muscle, also by the conjoined tendons which lie immediately behind the external ring ; the contracted form of the base of this opening, together with the intercolumnar fascia, the edge of the rectus, the triangular ligament, and the spermatic cord, may be all enumerated as additional protections to this part of the ab- domen. In this species of hernia the sac will be found covered by the integuments, superficial and intercolumnar fasciae, also by an apo- neurosis derived from the conjoined tendons, and from the fascia trans- versalis, which the tumour has pushed before it, though in some in- stances the latter has been found to have burst through these structures ; the sac will be also covered by the usual cellular capsule ; it is not covered by the cremaster, and in general it descends along the inner and anterior side of the cord, that is, the cord will be found external and inferior or posterior to it, but in some few cases the cord has been found passing across the neck of the sac, that is, anterior to it ; the sac is seldom or never, however, found between the cremaster muscle and the spermatic vessels, except occasionally, in one particular form of which I shall speak directly. The epigastric vessels lie to the iliac, or outer side of the neck of the sac ; in dividing the latter, therefore, in case this operation be required during life, the edge of the knife should be directed upwards, or upwards and inwards. It is safer, as a general rule, to divide the stricture directly upwards in all forms of inguinal hernia, because it is often extremely difficult, and in some cases even impossible to determine, during an operation, the exact spe- cies of the disease ; thus when an oblique inguinal hernia has conti- nued for a considerable length of time, the spermatic canal will be found altered in many respects from its natural condition ; it will have become dilated and shortened, and the abdominal rings expanded and approximated, so as to render it difficult to distinguish it from a direct inguinal hernia ; and again, the direct hernia sometimes protrudes more externally, that is, close to the pubal side of the epigastric vein and artery, in which case the tumour may be delayed for some time in the canal, and must descend with some obliquity to reach the external ring : direct, or ventro-inguinal hernia, therefore, appears under two dif- ferent forms ; one, which is the more common, protrudes directly through the external ring, on the outer edge of the rectus, this is named internal, or inferior direct hernia ; the other, which is less frequent, protrudes close to the pubal side of the epigastric vessels, external to the obli- terated hypogastric artery, and in the small peritoneal pouch between these, this is named superior, or external direct hernia ; both forms correspond in not protruding through the internal ring, as the oblique hernia does, but through the posterior wall of the inguinal canal, and in some parts of the triangular depression before alluded to ; both also are internal, or on the pubic side of the epigastric vessels ; the internal, or inferior, is between the hypogastric artery and the rectus ; and the DUBLIN DISSECTOR. 211 superior, or external, is between the hypogastric and epigastric arte- rii-s ; the superior may be retained for a longer or shorter period in the canal, as the oblique often is, and in its course downwards may pass between the cremaster muscle and the cord, so as to be covered by the former; hence, then, the obliquity of the tumour will render it impos- sible, before operation or dissection, to discriminate this superior, or external direct hernia from the ordinary oblique, and even when the parts are partially exposed during life, the presence of the cremaster will render the diagnosis equally difficult and uncertain. To divide the stricture directly upwards, is, therefore, the best general rule to adopt, when it exists at the neck of the sac, which is found to be its most frequent situation ; if it be in any of the more superficial tissues, the direction of the division is comparatively unimportant ; great cau- tion, however, is to be observed in all the steps of such an operation, as deviations from the common arrangements are not uncommon ; thus the sac, in oblique hernia, sometimes separates the vessels of the cord from each other, and instead of their being placed posterior to it, the vasdeferens, or the spermatic artery, or a plexus of veins, may be unex- pectedly found crossing, or coursing along the tumour ; in the direct species, also, the whole cord has been found passing in front of the sac, and in old hernue of large size, whether oblique or direct, parts often undergo strange alterations, in structure as well as in position ; it is of importance also to bear in mind, that when a stricture on a hernia is placed in the neck of the sac, a division to a very short extent only is required, the mere pressure of the edge of the bistoury against it some- times suffices, and this is fortunate, for when the neck has become very large it will be found to have formed, not only a close lateral at- tachment to the epigastric artery and veins, but by the approximation and dilatation of the rings, and shortening of the canal, it will often have become partially encircled by those vessels, so that a too exten- sive incision directly upwards may divide them ; no doubt, should such an accident occur, a little dissection will enable the operator to expose and tie them ; but for obvious reasons, in this case especially, prevention is better than cure. The next point to be attended to, in connexion with the anatomy of inguinal hernia, is the disposition of the peritoneum in this region, and to which we have already partially alluded : divide the transverse fascia from the rectus to the crest of the ilium, carefully separate it and turn it down towards the thigh ; a layer of cellular membrane, containing more or less adipose substance, is now exposed, covering the peritoneum ; this layer some consider (as was before mentioned) the deep layer of the transverse fascia, but it is a totally different structure from it, at least in this particular region ; it is mere sub-peritoneal cellular tissue, it increases in thickness as it de- scends to Pouj >art's ligament, from which it is reflected backwards and upwards on the front of the external iliac vessels, and on the back part of the peritoneum towards the spine ; internally it descends into the pelvis ; as it passes from Poupart's ligament towards that region it closes the femoral ring beneath this ligament on the inner side of the femoral P 2 212 DUBLIN DISSECTOR. vein ; in that locality it becomes much thickened, and is commonly named the crural septum, implying that it separates the thigh from the abdomen, or closes up the communicating passages between these, and as it must be pushed before a femoral hernia, and form an imme- diate coveiing to it, it is called its fascia propria ; make a transverse incision through the peritoneum, from the umbilicus to the ilium, raise and hold tense the membrane, and look from above downwards into the cavity ; from the umbilicus three projecting ridges are seen to de- scend, one in the centre (urachus) to the summit of the urinary blad- der, and one on either side (obliterated umbilical, or hypogastric arte- ries), diverging towards each inguinal region, and then bending backwards towards the side of the pelvis ; these lateral ridges are more prominent than the central one, and as each of these is covered by a duplicators of the peritoneum, they throw this membrane into three falciform processes, converging to the umbilicus and separating below ; by these three folds, four pouches are formed, two on each side ; these are termed the right and left external and internal inguinal pouches ; the external is very large and deep, and in corpulent persons, or in long continued constipation and distention of the bowels, is often very prominent through the parietes ; this external pouch extends out- wardly to the ilium, and is bounded internally by the hypogastric artery, to which the epigastric is nearly parallel, though often the latter is a little external to it ; the internal ring is at the inner side and lower part of this pouch, and, of course, external to the falciform projection of the hypogastric artery ; when the intestines in this pouch are subjected to much pressure from the muscles of the ab- domen, this process would appear to resist their slipping inwards towards the pelvis, and thereby encourage the protrusion of the perito- neum and its contents through the internal ring; accordingly oblique inguinal hernia always leads out of this external inguinal pouch into the spermatic channel. The internal inguinal pouch is much smaller and never so deep as the external ; it is between the folds formed by the hypogastric artery externally and the urachus internally, and it corresponds to the external ring and posterior surface of the inguinal channel ; it is this pouch which is generally protruded in direct, or ventro-inguinal hernia ; when the hypogastric cord and epigastric artery are not parallel, but the latter at some distance external to the former, we shall find a small pouch, or fossa between these ; this might be named the middle inguinal pouch ; it is separated from the internal by the hypogastric cord, and from the external (from which it is cut off) by the epigastric artery ; it corresponds to that portion of the pos- terior wall of the spermatic channel which is almost wholly formed by the transversalis fascia ; through this pouch that rare form of hernia, called superior, or external direct, or ventro-inguinal, protrudes. In the dissection of these muscles several vessels and nerves are met with ; they are of a small size, and, with few exceptions, of little prac- tical importance ; the superficial branches from the femoral artery, which are distributed chiefly to the integuments, to the superficial DUBLIN DISSECTOR. '2 I '.> fascia, and to the external oblique muscle, have been already noticed ; the rive or six inferior intercostal arid the lumbar arteries send branches forwards between the muscular laminae to inosculate with the internal mammary and epigastric arteries ; these two last-named ves- sels are chiefly distributed to the recti ; inferiorly and laterally the ilio- lumbar and circumflex ilii arteries also assist in supplying the abdomi- nal muscles ; the origin and course of the mammary arteries have been already noticed ; the intercostal and lumbar arise from the de- scending aorta, the ilio-lumbar from the internal iliac, and the epigas- tric and circumflex ilii from the external iliac. THE EPIGASTRIC arises from the trunk a little distance above Poupart's ligament, it first descends a little forwards and inwards, with a curve concave upwards, convex downwards, it then ascends obliquely, between the fascia transversalis and the peritoneum, behind the spermatic cord, or the round ligament, and at a little distance from the inner side of the superior abdominal ring ; the vas deferens appears to bend round it externally, and then passes posterior to it in its course to the pelvis ; this artery, therefore, ascends behind the in- guinal channel, and of course between the two rings, but much nearer to the internal, or superior, than to the external, or inferior ; oblique inguinal hernia commences on its outer side and descends anterior to it ; direct hernia occurs internal to it, or between it and the rectus muscle ; betAveen the pubis and umbilicus it perforates the thin fascia transversalis, enters the sheath of the rectus just below its posterior deficiency., ascends at first posterior to the muscle, but near the um- bilicus it enters its substance and anastomoses with the internal mam- man", the abdominal branch of which enters the sheath of the rectus above the posterior deficiency in it, just beneath the cartilage of the seventh rib, and descends to the first or second linea transversa, then enters the muscle ; shortly after its origin the epigastric sends off its internal branches, which pass behind Poupart's ligament and thepubes, to anastomose with the opposite artery, and to communicate in general very freely with the obturator ; when this latter communication is much developed, and at the same time the pelvic origin of the obtura- tor diminished or wanting, then the latter vessel is said to arise from the epigastric, and this very frequently occurs : near the internal ring the epigastric gives off one or two spermatic branches, which are chiefly distributed to the cremaster muscle and other coverings of the cord ; be- fore its termination in the rectus, it gives off external branches to the lateral muscles of the abdomen ; its accompanying vein or veins open into the external iliac vein, near Poupart's ligament. Tin. CUM IMFLKX ILII ARTERY arises opposite and near to the epi- gastric, it passes outwards and upwards towards the spine of the ilium, parallel to but deeper than Poupart's ligament, and enclosed in a strong fibrous canal already described ; near the ilium it pierces this and runs for a short way beneath the transverse muscle, and about the mid< lie of the crest of the ilium it passes through this muscle and then rami- li.- between it and the internal oblique, sending some branches for- 214 DUBLIN DISSECTOR. wards to meet those from the epigastric, and continues itself upwards and backwards parallel to the iliac crest, and anastomoses freely with the ilio-lumbar artery from the intemal iliac ; it also sends several branches into the iliacus muscle, which anastomose in a similar man- ner ; its trunk is accompanied by one or two veins which pass across the external iliac artery and join the iliac vein. See Vascular System. The nerves in the anterior and lateral abdominal walls are deiived from the five or six lower intercostals and from the lumbar plexus ; the intercostal branches extend forwards between the internal oblique and transversalis to the sheath of the rectus, perforate this and enter the muscle ; each then divides into two branches at least, one for the muscle, the other, accompanied by a small artery, pierces the muscle and its anterior sheath near the linea alba and becomes cutaneous ; the last dorsal runs downwards and forwards, and sends off a large cutaneous branch which pierces the two obliqui and descends over the crest of the ilium and is distributed to the integuments over the glutaei. The branches of the lumbar plexus are only two or three in number, are of great length, and take an oblique course downwards and for- wards towards the inguinal region, and are partly muscular, but prin- cipally cutaneous or superficial ; the first is named by some, superior musculo-cutaneous, by others ilio-inguinal, or scrota! ; it is derived from the first lumbar, passes through the psoas, and runs obliquely down wards and outwards in the sub-peritoneal cellular tissue ; at the crest of the ilium it divides into an abdominal and a cutaneous branch ; the first passes, similarly to the intercostal branches, between the oblique and transverse, to the rectus ; the cutaneous branch proceeds as far as the anterior superior spine of the ilium, then proceeds parallel to Pou- part's ligament and joins the spermatic cord, or round ligament, ac- companies it through the canal, and is finally distributed to the inte- gument of the pubes and groin. The next abdominal branch of the lumbar plexus, or smaller musculo-cutaneous, runs like the last as far as the spine of the ilium, communicates with it, accompanies the cord, and is lost in the inguinal and scrotal integuments. See Nervous System. In connexion with inguinal hernia, the student may next study the anatomy of the groin in reference to femoral or crural hernia, or he may postpone this dissection until the contents of the abdomen have been examined and removed ; we shall, however, here subjoin the description of the parts concerned in this disease. Remove the integu- ments from the anterior part of the upper third of the thigh ; the su- perficial fascia will be seen descending over Poupart's ligament to invest the lower extremity ; in the groin this fascia is of very variable structure, sometimes it is very thick, and may be divided into se- veral layers, which are separated by lymphatic glands and by the superficial inguinal vessels ; it may be easily raised from the fascia lata on the outer and inner sides of the thigh, but in the middle of the groin and about an inch below Poupart's ligament they are almost DUNLIN DISSECTOR. 215 inseparably joined; when the superficial fascia shall have been dis- sected oft" the forepart of the thigh, we shall see several lymphatic glands, the saphena vein, and some small blood-vessels, lying on the fascia lata ; the form and boundaries of the inguinal region also may * The abdominal rings and crural arch in the female. 1. The symphysis pubis. 2. 2. The tuberosity or spine of the pubis. 3. The anterior superior spinous pro- cess of the ilium. 4. 4. The extenial oblique muscles. 5. The linea alba. 6. The linea semilunaris. 7. Poupart's ligament or the crural arch. 8. The interco- lumnar fibres. 9. The external abdominal ring. 10. The iliac portion of the fascia lata. 11. The cribriform portion. 12. The pubic portion of the fascia lata, 13. The internal or pi-eater saphena vein. 14. Burn's ligament. 15. Hey's liga- ment. 16. The femoral sheath cut open. 17. The femoral artery. 18. The. fe- moral vein, the course of femoral hernia is on the inner side of the vein. 19. Ab- sorbent vessels within the sheath. 20. 20. Absorbent glands. 21. The internal circumflex ilii artery. 22. The internal epigastric artery, seen through the fascia transversalis. 2-3. The external oblique divided and raised. 24. The inter- nal oblique muscle turned upwards. 2->. The edge of the transversalis muscle turned upwards. 2fi. The fascia transversalis, passing up behind the transver- salis muscle. 27. 27. The round ligament of the uterus, descending through the internal abdominal ring, in the inguinal canal, above Poupart's ligament, and through the external abdominal ring, to be lost in the fat on the pubis. 216 DUBLIN DISSECTOR. then be more distinctly seen ; the term crural is sometimes applied to this space, and that of inguinal to the smaller region above Poupart's ligament ; I prefer naming the latter spermatic, and the former in- guinal, or superior crural. The inguinal region is triangular, the base is Poupart's ligament ; the apex is, inferiorly, formed by the meeting of the sartorius and adductor muscles, at the lower part of the upper third of the thigh ; the external side is veiy prominent, and consists of the sartorius, iliacus, rectus, and other muscles, all covered by the fascia lata ; the internal, or pubic side, is flat and on a plane posterior to the iliac ; it is fonned by the pectinscus and adductor muscles, also covered by the fascia lata. The inguinal lymphatic glands are irre- gular in number and size ; they are in general about twelve in number, and may be divided into a superficial and a deep set ; the former are the more numerous, and may be arranged, from their situation, into the superior and inferior ; the superior are small, four or five in num- ber, lie parallel to Poupart's ligament, some above, others below it ; the inferior are two or three in number, larger than the former, and placed perpendicularly, or parallel to the saphena vein ; in general one lies behind this vessel, near its termination, and sometimes so low down as the middle of the thigh ; the deep inguinal glands are be- neath the fascia lata, are three or four in number, and are closely con- nected to the sheath of the femoral vessels, chiefly to its inner side ; in general one occupies the femoral ring ; the inguinal glands are usually more developed in the young than in the old ; their number is very uncertain and generally in an inverse ratio to their size, as if in some cases one gland was subdivided into several, and in others se- veral united into one. The saphena vein is the principal cutaneous vein of the lower ex- tremity ; it will be seen in a future dissection to arise from the dorsuin and inner side of the foot, and to ascend in front of the inner ankle along the inner side of the leg, and passing behind the inner condyle of the femur it continues to ascend along the inner and anterior part of the thigh to within about an inch and a-half of Poupart's ligament, where it passes through an opening in the fascia lata (the saphenic opening), and joins the femoral vein about an inch or an inch and a-half below the crural arch. The saphenic opening in the fascia lata will be veiy distinctly seen if the vein be divided on the thigh and raised toward's Poupart's ligament, it presents a well-marked semilunar edge (Burn's ligament), the concavity looking upwards ; this edge, though apparently sharp, yet if carefully examined will be found re- flected backwards on the sheath of the femoral vessels : remove the superficial inguinal glands, clean the surface of the fascia lata, to the connexions of which in this region the student should next attend. The fascia lata may be observed to be united to the spine of the ilium, to the whole length of Poupart's ligament, also to the linea innominata and spine of the pubis ; it covers the muscles on either side of the groin, and the vessels in the middle ; for the pur- pose of more particular examination, it may be divided in this region DUBLIN DISSECTOR. 217 into three portions, the internal, or pubic, orpectineal portion, the ex- ternal or iliac, and the middle or cribriform ; the internal or pubic portion covers the pecthuvnis, gradlis, and adductor muscles, and is inserted internally into the ramus of the ischium and pubis ; superior- Iv into the linea innominata or ileo-pectinea, anterior to Gimbernaut's ligament ; externally it passes behind the sheath of the femoral vessels, and at the edge of the psoas tendon divides into two lamina;, one passes beneath that tendon, and is attached to the capsular ligament of the hip-joint ; the other passes over that tendon and is continued into the deep surface of the fascia iliaca. The middle portion of the fascia lata is very thin, and has been termed the cribriform fascia : this extends from the saphena vein to Poupart's ligament, and is con- nected on either side to the pubic and iliac portions of the fascia lata. The cribriform fascia is limited to a small extent, it covers the femo- ral vessels, adheres intimately to their sheath, and is perforated by the lymphatic vessels passing to the deep lymphatic glands; this por- tion of the fascia lata is more closely connected than any other to the superficial fascia ; indeed in structure it resembles the latter more than the former, nor are all its fibres directly continued from those of the fascia lata ; some have, therefore, considered the cribriform fascia as a deep lamina of the superficial ; in many cases, however, it has an aponeurotic structure, and appears to be clearly derived from the iliac portion, and inserted into the pubic portion of the fascia lata ; it pre- sents much variety in this respect. The external or iliac portion of the fascia lata is very dense and strong, it is continued from the ex- ternal surface of the thigh, and is intimately attached superiorly to the spine of the ilium, and to Poupart's ligament ; and, uniting with the cribriform fascia, is continued in front of the femoral vessels, along with the inferior or reflected fibres of Poupart's ligament, and is in- serted along with these into the linea innominata, thus assisting to form the external part or the base of Gimbernaut's ligament. If the cribriform fascia be removed along with the superficial fascia, then the iliac portion of the fascia lata will present the appearance of a crescen- tic or falciform process, extending across the femoral vessels, the con- cavity looking downwards and inwards ; the inferior cornu joins the external cornu of the saphenic opening, and the superior cornu (Key's ligament) is inserted, along with the reflected fibres of Poupart's liga- ment, or Gimbernaut's ligament, into the linea innominata, on the internal border of the crural ring ; although this crescentic process appears to present a defined edge, yet if the latter be examined closely it will be found reflected backwards on the sheath of the vessels, and on the muscles external to them, in the same manner as the apparent edge at the lower part of the saphenic opening, beneath the saphena vein. When the thigh is extended and rotated outwards, this portion of the fascia lata will be found very tense, particularly the superior cornu of this falciform process, and if the limb be put into the oppo- site position, it will become relaxed, hence, then, in performing the taxis for the reduction of femoral hernia, the thigh should be flexed,. 218 DUBLIN DISSECTOR. Fig. 41.* * A vertical section passing transversely through the lower part of the abdo- men, and through the iliac bones, hip joints, femora, and ischia. This plate re- presents the peritoneum lining the inferior portion of the anterior wall of the abdomen, the posterior wall of the abdomen and pelvis having been removed. On the right side the peritoneum has been detached, and drawn over to the left side, in order to expose the parts upon which it was applied. 1. A horizontal section of the anterior wall of the abdomen a little below the umbilicus. 2. 2. A vertical section of the lateral walls, including the external oblique, internal ob- lique, and transversalis muscles. 3. 3. A section of the iliac bones. 4. 4. Section of the acetabula. 5. Section of the tuber ischii. G. Section of the femur. 7. Sec- tion of the glutseus maximus. 8. Of the glutams nredius. 9. Of the glutajus minimus. 10. Section of the vastus ex ternus. 11. The external obturator mus- cle. 12. Part of the adductor magnus. 13. Section of the psoas and iliac mus- cles. 14. The fascia transversalis exposed by the removal of the peritoneum. 15. The internal abdominal ring. 16. The posterior wall of the inguinal canal. 17. Gimbernaut's ligament. 18. The posterior surface of the rectus muscle. 19. The iliac fascia, covering the iliac and psoas muscles. 20. The pelvic fascia. 21. The spermatic vessels divided just above their entrance into the inguinal canal. 22. The divided extremity of the external iliac artery. 23. The external iliac vein. 24. The internal epigastric artery and vein. 25. The vas deferens. 26. The vesicula seminalis of right side. 27. The obturator artery. 28. Part of the posterior surface of the bladder deprived of its peritoneal coat. 29. Section of the levator ani muscle. 30. Section of the internal pudic artery and vein. 31. Section of the internal obturator muscle. 32. External sxirface of the peri- toneum, detached from part of the posterior surface of the bladder. 33. The peritoneum passing from the anterior wall of the abdomen to the summit and posterior surface of the bladder. 34. The peritoneum covering the posterior surface of the bladder. So. Its continuation covering the anterior surface of the iH r.i.iN i>i -SKCTOR. ZW addueted. and rotated inwards ; thus this process of the fascia, lata will be relaxed, and the crural ring more easily enlarged, for it is obvious that these fibres bound this opening anteriorly and internally, together with the reflected fibres of Poupart's ligament: there can, I conceive, be little doubt but that the upper and internal part of this falciform process is often concerned in forming the strangulation on femoral hernia. The close connexion between Poupart's ligament and this portion of the fascia lata imparts considerable strength to this re- gion, and draws this ligament downwards and backwards, so as to strengthen and assist in closing the external portion of the crural arch. Next direct your attention to the internal surface of the crural arch, and to the connexion between it and the deep fasciae of the abdomen, viz., the transversalis and iliaca : first cut across the cord or round ligament, next divide the fascia transversalis from the spine of the ilium towards the rectus muscle, and dissect it down from the perito- naeum, then, in the same direction, carefully separate from the latter the cellular layer which is attached to it ; finally, push upwards, and secure in that position, the peritoneum with the contained viscera ; the loose connecting cellular tissue in the iliac fossa readily admits of this separation ; the first object now to be attended to is the detached lamina of cellular membrane which was interposed between the peri- toneum and the fascia transversalis, and to which it is difficult to apply a name at once appropriate and unobjectionable. Some have called it the deep layer of the fascia transversalis ; this, however, is incorrect, as it is of a totally different tissue, and is separated from it by bloodvessels, and has also a considerably greater extent ; others have named it the subperitoneal or subserous cellular tissue, which it really is ; this name, however, does not seem very appropriately ap- plied to a structure which is to be examined detached from, and un- connected to that membrane ; the term crural septum has also been applied to it, and to a certain extent correctly, for it forms a partition between the thigh and the iliac region of the abdomen; it has also been designated as the fascia propria, because in herniae, whether inguinal or crural, this membrane must be protruded before the peritoneal sac, to which, therefore, it forms an immediate proper covering; under this title, then, we shall examine it, admitting, however, that this name is very open to criticism, it is in fact applying to a natural or normal structure a name derived from its unnatural or abnormal state ; su- periorly, then, this membrane is fine and delicate, merely serving as a connecting medium to the peritoneum ; inferiorly it is increased in thickness, is laminated, and contains more or less adipose substance, and is separated from the fascia transversalis by the epigastric ves- sels ; it lines Poupart's ligament, and rounds off the angle, by filling rectum. "0. Elevated fold of peritoneum, formed by the projection of the urachus and left umbilical artery. -J7. External inguinal pouch. 38. Perito- neum, de.scemling from the lateral wall of the abdomen over the internal iliac muscle, over 3J. The external iliac artery and vein, into the cavity of the pelvis. 220 DUBLIN DISSECTOR. up the interstices, between it and the iliac vessels as they descend be- hind it ; from this ligament the fascia propria is reflected upwards and backwards, externally over the iliac fascia, in the middle over the ex- ternal iliac artery and vein, and internally it passes across the femoral ring towards the cavity of the pelvis ; in the first or external portion it serves as a loose and cellular connexion between the iliac fascia and the peritoneum, as also between the former and the coecum intestine on the right side, and the sigmoid flexure of the colon on the left ; in its middle portion, that is, in its inflection on the forepart of the iliac ves- sels, it is thin but firm and strong, and adheres on either side of them to the iliac fascia, which is behind these vessels, it thereby retains these in their position along the margin of the pelvis, and binds the vein and artery so closely together, that in the operation of passing a ligature around the latter, much difficulty has been experienced in se- parating these vessels ; this difficulty, however, is easily surmounted by first making a small opening in this fascia and then tearing it to the extent required ; internal to these vessels, and close to Poupart's liga- ment and the pubis, the internal portion of this fascia becomes very thick, passes across the femoral ring, and is depressed into it, so as to present a concavity above ; this portion is often strengthened by apo- neurotic fibres traversing it from the fascia transversalis in front to the fascia iliaca behind, that is, from the anterior to the posterior part of the sheath of the vessels, and of the crural ring ; this is the proper crural septum, it often contains a lymphatic gland ; a cluster of lymphatic vessels always ascend through it ; this serves to protect this portion of the crural arch against a hernia, and when the latter does occur, this is protruded before it, and as it is essentially cellular it yields to distention, and forms a regular investing capsule for the hernial sac, hence the term fascia propria ; in its natural or normal state then, the term crural septum is correctly applied, but in its ab- normal condition, that is, when protruded before and around a hernia, its proper title is fascia propria ; the uses, therefore, of this structure generally, are : first, to serve as a connecting medium to the perito- neum, in which its nutrient vessels may ramify ; secondly, to add to the strength of the inferior or inguinal regions of the abdomen, by connecting the several structures more intimately together, and by filling up the angular interstices between substances of different form and consistence ; thirdly, it retains the external iliac vessels in a fixed position, and lastly, and above all, it closes the femoral ring, and thereby affords much security against the occurrence of femoral her- nia. This membrane may now be detached from this region, when we shall obtain a clear view of the internal surface of Poupart's liga- ment, of the parts which pass beneath it, and which fill the space or cavity of the crural arch, also of the attachments between Poupart's ligament, the fascia transversalis, and iliaca. To the fascia iliaca we shall next pay some attention. This is a distinct, and, in some situations, a very strong aponeurosis, principally developed in the iliac region, and hence its name ; it may be said to DUBLIN DISSECTOR. 2'J 1 arise from the inner border of the entire crest of the ilium, and from Poupart's ligament external to the iliac artery ; it expands over the iliac and psoas muscles, ascends on the latter as high as the dia- phragm, and is attached to the ligamentum arcuatum above, and internally and laterally to the sides of the lumbar vertebra?, forming a >eries of tendinous arches over the lumbar arteries and the communi- cating branches between the sympathetic ganglions and the lumbar spinal nerves ; each arch is opposite the groove on the side of the body of each vertebra ; the last arch is very large and strong, extend- ing from the last lumbar vertebra to the brim of the pelvis, the ob- turator and lumbo-sacral nerves pass beneath it ; from the spinous process of the ilium to the iliac artery, this fascia is intimately united to Poupart's ligament by a strong tendinous attachment which is also common to the fascia transversalis ; it is from this common tendinous structure, rather than from the ligament itself, that the lower fibres of the internal oblique and transverse muscles arise ; a dense opaque line marks it distinctly, this encloses the internal circumflex ilii ves- sels ; immediately on the outer side of the iliac artery the fascia se- parates from Poupart's ligament, presents a semilunar border towards the vessel, and then passing behind both the artery and vein and the crural ring, it descends into the thigh, forming the posterior part of the sheath of the femoral vessels, and lying in front of the psoas and iliac muscles, and of the anterior crui-al nerve; it adheres to these mus- cles, and internal to these to the pubis and to the capsule of the hip joint, and becomes continuous with the pubic or pectineal portion of the fascia lata ; from the iliac fossa it also passes inwards, behind the extemal iliac vessels, and is implanted into the thick fibrous covering of the lateral brim of the pelvis ; the psoas parvus tendon (when pre- sent) is blended with it by a broad expansion over this line, the fibres of each, however, pursue a different direction. The iliac fascia is thin superiorly on the psoas, stronger on the iliacus, but does not adhere closely to either, cellular tissue, and sometimes adeps being interposed ; its fibres are mostly transverse ; the lumbar nerves are all posterior to it. except some small, perforating, abdominal, and inguinal branches ; as it passes behind the femoral vessels, it separates the artery in front from the anterior crural nerve, which is pressed down behind it into a groove between the psoas and iliac muscles. The iliac and transverse fascia? are not only connected, or rather continuous with each other throughout the whole distance between the iliac artery and the spine of the ilium, but even when they have separated and descended into the thigh, the transverse in front of the vessels and the iliac behind them, they are still connected by two vertical antero-posterior pro- or septa, passing from the one fascia to the other, the first is between the artery and vein, the second is on the inner side of the vein, between it and the femoral ring and canal, and, in the case of a femoral hernia, will separate the tumour from that vessel, and prevent it compressing the latter. The iliac fascia serves, in the first place, as a firm covering to the psoas and iliac muscles ; -,,ndly, it affords considerable strength to the lower part of the 222 DUBLIN DISSECTOR. abdomen, by its firm adhesion to Poupart's ligament, which it ties down so closely as to contract the crural arch, and effectually prevent any abdominal protrusion through it between the artery and the spine of the ilium ; thirdly, it forms the posterior part of a smooth canal or sheath, for the passage of the femoral vessels and lymphatics, as the trans versalis fascia forms the anterior, and lastly, by means of the connecting septa between these two, the sheath is retained of the ne- cessary size only, and a strong resistance offered to its distention. The attachments of the iliac fascia would appear capable of exert- ing some influence on the course of purulent collections, which have formed higher up in either the subserous, or peritoneal, or in the sub- aponeurotic cellular tissue ; in either case it is a barrier, confining the fluid to the tissue in which it has been formed ; in either case the fluid may descend towards the groin, but if it be in the subserous tissue it will lie anterior to the great vessels, whereas it will be behind these if in the subaponeurotic, at least until it arrives in the thigh, where its further course may become modified by the connexions of the fascia lata. The fascia transversalis has been already minutely described in the anatomy of inguinal hernia, we have now, therefore, only to ob- serve its intimate attachment to the inner lip of the ilium and to Pou- part's ligament from the spine of that bone, as far as the pubis, into the linea innominate of which it is inserted ; here also it is inseparably joined to the conjoined tendons of the internal oblique and transverse muscles ; as this fascia is passing anterior to the iliac or femoral ves- sels, a portion of it extends beneath Poupart's ligament, in front of these vessels, so as to form the anterior part of their sheath, as well as of the crural ring and crural canal ; this process of the fascia trans- versalis soon becomes thin and indistinct, and is lost in the cribriform part of the fascia lata. The fascia ti'ansversalis and iliaca are not in- aptly compared to a funnel, containing in the superior wide portion the peritoneum and its contents, and enclosing in the inferior nai'row part, or pipe, the femoral vessels, and one or two lymphatic glands ; of this funnel the fascia transversalis forms the anterior, and the fascia iliaca the posterior wall ; these fasciae may now be seen to be perfectly continuous with each other, between the vessels and the spine of the ilium, different names only being applied to different portions of one extensive aponeurosis ; as the iliac and transverse fasciae are continued one into the other, external to the iliac artery, the white line already noticed may be again observed. The student should next consider how the space, commonly called the crural arch, is naturally filled ; that portion of it between the spine of the ilium and the iliac or femoral artery is occupied by the psoas and iliac muscles, imbedded between which is the anterior crural nerve : on the pubic side of these muscles is the femoral artery, crossed at a right angle by the circumflex ilii vein ; next to the artery is the femoral vein, and at a little distance to the pubal side of this vessel is Gimbernaut's ligament, which closes the internal part of this space ; thus almost all the crural arch is filled, except a small portion DUBLIN DISSECTOR. 223 between the femoral vein and the third insertion of Poupart's or Gim- bernaut's ligament ; this space is the femoral, or crural ring ; this is somewhat of a triangular form, the base, externally, is the femoral vein, the apex internally is Gimbernaut's ligament ; it is bounded an- teriorly by Poupart's ligament, and by the superior fibres, or cornu of the falciform process of the fascia lata, and posteriorly by the pubis, covered by the pectineal muscle, and by the pectineal portion of the fascia lata : the spermatic cord, or the ligamentum teres, lies on the anterior boundary of this opening, and above it, and still closer to it in front, is a small artery with its vein, branches from the epigastric vessels, which are passing inwards to the back part of the pubis ; this artery generally inosculates with the obturator ; this last-named ar- tery, which is normally a branch of the internal iliac, very frequently arises from the epigastric and then takes the course of the small anas- tomosing branch just mentioned, in front of the ring, and then drop- ping along its internal side into the pelvis ; this very frequent anomaly in this vessel, we may regard as an hypertrophy, or excessive de- velopment of this anastomosis, and a proportional diminution in the size of the more regular artery ; the epigastric vein and artery as- cend obliquely inwards along the outer and upper angle of this open- ing, so that bloodvessels surround it on all sides except posteriorly and internally, and even in the latter aspect also, when the obturator artery springs from the epigastric, as, in such a case, it may pass first in front, and then along its inner border, although occasionally it passes along the posterior border of the ring in its inward course to the pelvis. Gimbernaut's ligament prevents femoral hernia occurring internal to this space, which is the only part in the crural arch where a hernia can descend, and even here this accident is in a great degree guarded against, as a lymphatic gland generally occupies this situa- tion, and the layer of condensed cellular membrane, already described as the crural septum, extends across the opening, and as this must be carried down before the hernial sac, so as to form a covering for it, it has been also named the fascia propria ; this fascia, though often weak and indistinct in the natural and healthy state, becomes very thick and strong in cases of old femoral hernia. We should bear in mind that Gimbernaut's ligament is composed of the combined fibres of Poupart's ligament, and of the falciform process of the fascia lata ; the latter fibres form its outer part, or base, that is, the portion nearest to the ring ; this marginal base is somewhat crescentic, and is very similar to the semilunar border formed by the fascia iliaca on the outer side of the iliac, or femoral artery ; so that the upper, or pelvic extremity, or opening of the crural sheath, presents a transversely el- liptical figure; its anterior boundary is formed of fascia transversalis, Poupart's ligament, and the iliac portion of the fascia lata ; its poste- rior boundary is funned of fascia iliaca, and the pubic portion of the favia lata, covering the pubis, the pectineus, psoas, and iliac muscles, and the anterior crural nerve ; the lateral angles, or commissures, are the two semilunar borders just alluded to. The entire of this opening 224 DUBLIN DISSECTOR. may be considered as divided into three parts, or tubular processes, the external for the artery, the middle for the vein, and the internal is the crural ring, or canal. Crural hernia cannot occur external to the ring, as there the femoral vessels fill up the space, and strong partitions pass from the fascia trans versalis to the fascia iliaca, one on the inner side of the vein, and another between it and the artery ; these septa pre- vent the distention of the sheath ; the fascia propria also rounds off the angle between the fascia transversalis and the forepart of the vessels, and prevents a hernia occurring in front of the artery or vein ; exter- nal to these vessels the crural arch is completely closed by the close connexion between the fasciae, lata, transversalis, and iliaca, to Pou- part's ligament, in front of the psoas and iliac muscles. Femoral her- nia, then, can occur only at the femoral or crural ring ; this disease is more frequent in the female than in the male, the crural arch and ring being larger in the former than in the latter ; femoral hernia descends through a sort of canal which commences at the crural ring, and ends at the saphenic opening in the fascia lata, narrowing as it descends ; this canal is but the internal portion of the crural, or femoral sheath, and is separated from the femoral vein by the internal septum before described ; it is occupied by cellular tissue, lymphatic vessels, and very frequently by a gland ; it is closed above by the crural septum, or fascia propria, and below and in front by the cribriform fascia ; al- though it descends as low as the entrance of the saphena into the fe- moral vein, it does not follow that when a crural hernia enters this canal, it should descend to this point before it comes forward ; some writers have affirmed that it does ; my own experience, however, both in the living and the dead, induces me to doubt this, for I have found that the tumour had forced through the inner side of the canal at a point much higher than this. The hernial sac, in descending, car- ries before it the fascia propria, descends in the sheath of the vessels along the inner side of the vein, and may remain in this situation for a considerable time ; as the tumour increases in size it bursts through the sheath, and either tears or dilates some opening in the cribriform fascia, and then turns forwards into the groin ; if the tumour in- crease still further it is found to turn upwards over Poupart's liga- ment between the superficial and deep fasciae of the abdomen, and to rest on the lower part of the tendon of the external oblique, generally in the direction of Poupart's ligament, and therefore there is often some difficulty in distinguishing between a femoral and an inguinal hernia ; the form of the crural ring, the course of the superficial epigastric ves- sels, the close connexion between the superficial and cribriform fasciae, together with the frequent flexion of the limb, account for its ascending in this manner. If we dissect off the integuments from a femoral her- nia of long standing, we shall find beneath them the superficial fascia, often so increased in thickness and vascularity as to present a compact and almost fleshy-like appearance ; when this shall have been divided, the tumour can be brought down off the abdomen into the groin, and will be found covered by a dense and smooth capsule, which often pre- DUBLIN DISSECTOR. 220 a glossy appearance ; this is the fascia propria ; in dissecting oft' this, it will in general be found to consist of several lamina;, which MM nt 'times separate so easily and appear so distinct as to lead an in- experienced operator to suppose that the hernial sac itself is exposed. These, then, are the coverings of the sac, which is thus placed ex- ternal or superficial to the fascia lata : the neck of the sac, however, it is to be recollected, lies deep within the sheath of the vessels, and is, therefore, covered by the fascia transversalis, by the superior cornu of the falciform process of the fascia lata, and by the reflected fibres of Poupart's ligament passing backwards and inwards to their pubic in- sertion. Let the student now review the dissection that has been made ; let him move the thigh hi different directions, and he will remark that, when it is rotated imvards, .Poupart's and Gimbernaut's ligaments, as well as the fascia lata, feel relaxed, and that the crural ring will become larger or more dilatable ; let him also observe the relation of the fe- moral vein, the epigastric vessels, and the spermatic cord, or round ligament, to this opening ; pass up the finger from the groin into the crural ring, and suppose that the stricture on femoral hernia was seated there, and that this opening required to be dilated, he will now perceive that this may be done with most safety, by directing the edge of the bistoury forwards and a little inwards, so as to divide the exter- nal edge or base of Gimbernaut's ligament, which edge is composed of the insertion of the superior cornu of the falciform process of the fascia lata. The stricture on femoral hernia may be, however, and I believe very often is, seated lower down than in the neck of the sac ; it may be situated in that opening of the cribriform fascia through which the hernial sac has protruded ; in such a case, the stricture may be easily divided by directing the edge of the knife directly inwards along the surface of the pectinajus muscle ; or it may be caused by the superior cornu of the falciform process of the fascia lata twisting in from the forepart to the inner side of the tumour ; the exact position of the stric- ture can only be known during the operation ; in whatever tissue it is seated it is only necessary to pass the bistoury guided by the tip of the finger beneath it, and, turning the edge towards it, to press gently against it ; this will, I believe, in all cases, effect a safe division, and one sufficiently free for all practical purposes.* * The following measurements of the parts engaged in or referred to in the fore- going account of the anatomy of inguinal and femoral hernia have been ex- t rue-ted from Sir Astley Cooper's valuable work on hernia, and have been sanctioned liy several other writers on the same subject : I have tested these very frequently, and though I can bear testimony to their general accuracy, I must i >l iserve, 1 have found deviations to have occurred so frequently, and in cases where there was no Issi;tTOK. 231 this muscle, particularly in the left hypochondriuiu ; from the dia- phragm it is reflected on the left side, on the back part of the splenic rands, ami of the spleen, and is continued round the convex surface of this organ to the forepart of its vesssels ; more centrally it is re- flected on the stomach, and on the liver on the right side ; it is also re- flected on this last-named viscus by a distinct fold, the falciform, or suspensory ligament, which extends from the umbilicus, and from the abdominal muscles on the right side of the linea alba ; this fold con- tains the ligamentous remains of the umbilical vein : as the peritonaeum is reflected from the diaphragm on each side of these organs in the epigastric and hypochondriac regions, it forms folds, which to a certain extent, serve as ligaments ; these will be noticed more particularly in the examination of the individual viscera. Having covered the organs in the upper division of the abdomen, it is continued downwards in the following manner ; having invested both surfaces of the liver as far as its transverse fissure, it is conducted along and around the ves- sels of this gland towards the lesser curvature of the stomach ; this fold, which thus surrounds the hepatic vessels, is called the lesser or the gastro-hepatic omentum; it is also sometimes, but incorrectly, named the capsule of Glisson ; at the lesser arch of the stomach the two lamina? of this process separate to enclose this organ, the posterior layer giving a serous covering to its back part, and the anterior layer to its forepart, on which it is continuous with that portion of perito- naeum which has descended from the diaphragm, and with that which is also continued from the spleen to the stomach. The peritonaeum hav- ing thus enclosed the stomach and its vessels between the tAvo layers of the lesser omentum, we next observe that these laminae having passed the great curvature of the stomach, touch each other, and being joined by the peritonaeum from the splenic vessels and from the lower end of the spleen, descend, under the name of the gastro-colic or the great omen- turn, to the lower part of the abdomen ; in general this descends lower on the left side than on the right ; it then turns on itself, and ascends obliquely backwards to the arch of the colon, along the convex edge of which its laminae separate to enclose this intestine and its vessels ; along the concave edge of the colon these laminae again unite, and, in- creasing in density, form that process which is called the transverse meso-colon, which passes backwards to the spine : opposite the duode- num this process separates into an ascending and descending layer ; the inferior division of the duodenum lies between these ; the ascending layer proceeds in front of the lower and middle divisions of the duode- num and of the pancreas, to the back part of the right lobe of the liver, where it becomes continuous with the peritonaea! tunic of that viscus, and with the posterior layer of the lesser omentum, which is de- from the forepart of the uterus to the back of the bladder. 14. 14. The same layer passing from the superior fundus of the bladder to the abdominal muscles, on the inner surface of which it may be traced up to 1, on the infeiicr surface of !he diaphragm. 232 DUBLIN DISSECTOK. scending along the back part of the hepatic vessels. The descending layer of the transverse meso-colon expands into each lumbar region^ in which it attaches the lumbar portions of the colon by a duplica- ture, very variable in extent, called the right and left lumbar meso- colon ; in the centre the inferior layer of the transverse meso-colon Fig. 44.* * A transverse section of the abdomen, shewing the manner in which the pe- ritonaeum forms the mesentery, and covers the intestines without inclosing them in its cavity ; the section passes through the body of the last dorsal vertebra, obliquely downwards and forwards to a little below the umbilicus. Nearly the entire of the small intestines has been removed. 1. 1. Sections of the recti muscles of the abdomen. 2. A section of the external oblique, internal oblique, and transver- salis muscles. 3. Section of the lumbar mass of muscles. 4. Spinous process of twelfth dorsal vertebra. 5. The body of the twelfth dorsal vertebra. 6. The twelfth rib. 7. Transverse section of the kidney. 8. The inferior vena cava. 9. The abdo- minal aorta. 10. The right or ascending colon cut transversely. 11. The caecum and appendix venniformis, as seen from above. 12. The ileum cut transversely. 13. Its termination in the caecum. 14. The descending colon at its sigmoid flexure divided transversely. 15. the upper part of the rectum. 16. The supe- rior fundus of the bladder, covered by the peritonaeum. 17. The urachus raising up the peritonaeum in the median line, as it passes to the umbilicus. 18. 18. 18. The peritonaeum lining the anterior and latei'al walls of the abdomen. 19. The peri- tonaeum leaving the abdominal wall to envelope the left lumbar colon. 20. The peritonaeum returning to the abdominal wall, thus forming 21. The left lumbar meso-colon. 22. The continuation of the same layer of peritonaeum passing in front of the left kidney, renal vessels, abdominal aorta, and inferior cava. 23. The peritonaeum leaving the great vessels, enveloping the ileum, 24. and return- ing to the spine, 25. thus forming 26. The mesentery. 27. The peritonaeum pass- ing in front of the right kidney to the lateral wall of the abdomen. 28. The same layer leaving the lateral wall to envelope the right lumbar colon. 29. The peri- tonaeum leaving the colon to reach the lateral wall, thus forming 30. The right lumbar meso-colon. From this point the peritonaeum may be traced along the internal surface of the lateral wall to 18. where its description commenced. DUUL1X DISSECTOK. 233 adheres to the vertebral column, and to the great vessels which lie upon it, and is thence reflected forwards and downwards, over the small intestines and their vessels, and returns around these to the spine, thus forming a very important and remarkably folded, or plaited process, named the mesentery. From the inferior surface of the me- sentery the peritonaeum extends laterally into either iliac region, and in the* middle it descends, in front of the sacro-vertebral prominence, and of the aorta and iliac vessels, into the pelvis ; it serves to connect the caecum and the vermiform appendix by a small mesentery in the right, and the sigmoid curve of the colon in the left iliac fossa ; in the pelvis the peritonaeum descends around the rectum, forming the process named the meso-rectum ; opposite the lower third of the sa- crum it is reflected, in the male, to the lower and back part of the bladder, forming two lateral semilunar folds, called the posterior liga- ments of the bladder, between which it is depressed into a deep cul de sac, which descends to within a short distance of the prostate gland, and between the vesiculae seminales. In the female it is reflected from the rectum to the upper and back part of the vagina, from which it ascends on the uterus, and forms on each side of this organ the broad ligament which is subdivided superiorly into three smaller folds, the anterior containing the round ligament, the middle the Fallopian tube, and the posterior the ovary ; the peritonaeum is then reflected from the forepart of the uterus to the back of the bladder, and forms a cul de sac between them ; it has no connexion to the lower fourth of the ute- rus, or to the vagina in front, though it covers the upper third of that canal behind ; it then ascends, in either sex, along the posterior sur- face and sides of the bladder to its superior fundus ; its extent on this organ is very variable, according as the latter is empty or distended ; when it is contracted the peritonaeum descends behind the pubis, but when distended it rises into the abdomen, pushing the peritonaeum above it, and comes into cellular contact with the lower portion of the rccti ; from the bladder and from the iliac fossa? it is continued to the abdominal muscles, and may then be traced on the inner surface of the recti and transversi up to the umbilicus, where the sac was opened ; between the pubis and this point it is raised by the ligamentous re- mains of the urachus and umbilical arteries into three falciform folds, Avhereby the four inguinal pouches are formed. Although the perito- naeum has been thus traced as one uninterrupted surface, a sac -without an opening, yet there is an exception to this statement ; in the female pelvis, the serous and mucous membranes are continued into one another through the open fimbriated extremities of the Fallopian tubes ; this, which is the only exception in the human body to the perfectly closed condition of serous membranes, is somewhat analogous to the lateral anal openings in the abdomen of many fish, whereby the peritonaeal cavity communicates by an oblique passage on either side with the surface of the body ; in the human female, however, these fimbriated extremities are probably closed at all times except when in contact with, or adhering to the ovaries ; if such be the case, the serous mem- brane is still a shut sac, and the exception is more an apparent than a 234 DUBLIN DISSECTOR. real one ; during life \ve never find the water in ascites escaping by these channels, neither in the dead body air or fluid when injected into the peritonaeum. The different folds which the peritonaeum forms in this course are termed processes, the principal of which, in addition to the ligaments of the several organs which shall be noticed in the description of the latter, are the lesser omentum, the great omentum, the splenic omentum, the colic omentum, the appendices epiploicae, the transverse, and the right and left lumbar meso-colons, the mesentery, meso-caecum, and meso-rectum. The lesser, or gastro-hepatic omentum, consists of two lamina 1 , which extend from the transverse fissure of the liver to the lesser cur- vature of the stomach and to the upper part of the duodenum ; it con- tains between its layers the vessels of the liver, viz., the hepatic artery to the left side, the ductus choledochus to the right, and the vena porta behind and between both ; at its connexion to the stomach it encloses the coronary vessels of this organ ; the lesser omentum lies anterior to the foramen of Winslow ; it seldom contains much adipose sub- stance. The great or gastro-colic omentum consists of four laminae, that is, of two descending, and two ascending ; the former descend from the lower end of the spleen, and from the anterior and posterior surfaces of the stomach ; between these laminae are several long and tortuous vessels, descending from the vessels of the stomach, between its two anterior laminae, to its lower border ; they then turn up and ascend between its two posterior layers as far as the colon, on which in- testine they anastomose with the colic arteries ; between these laminae also is some adipose substance, the quantity of which varies very much in different subjects ; it is chiefly deposited along the blood- vessels, and often amounts to a considerable quantity in the adult ; in the child the omentum is usually very thin and free from fat ; in the adult also it is often cribriform, or very thin and transparent ; in extent also, as well as in structure, it is very variable : the omenta are the only portions of this serous membrane visibly supplied with bloodvessels; the finest injections demonstrate a network of capillaries external to the membrane, but these never permeate it, so as to appear on the serous surface ; it is difficult, therefore, to account for these omental arteries ; they may maintain some useful anastomosis between the gastric and colic arteries ; they exist in the omentum of the young, where there is as yet little or no adipose de- posit ; in fact, although the omentum is anatomically traced as a con- tinuation of the peritonaeum, it yet appears a totally different structure when minutely examined by the microscope, as well as when regarded physiologically or pathologically ; various opinions are entertained as to its uses or functions, but it appears to me to be wiser to admit that these are still unknown. The great omentum descends in front of the large and small intestines to the lower part of the abdomen, in general lower on the left than on the right side ; (this explains the reason why the omentum is more frequently found in a hernial sac on the left than on the right side) ; it then turns upwards and backwards DUBLIN DISSECTOR. 235 until it reaches the transverse arch of the colon ; that portion of omen- tuin, therefore, winch is inferior to the colon, consists of four lamina?, two descending and two ascending ; these, though shorter in the very young subject than in the adult, can often be separated from each other, and a distinct cavity can be seen between them ; this is part of the cavity or bag of the omentuni which communicates with the gene- ral cavity of the peritonaeum by the opening of Winslow, and which will be more particularly described presently ; at the arch of the colon the two ascending laminae of the great omentuni separate to enclose this intestine, and, again uniting, form the commencement of the fol- lowing process. The transverse meso-colon extends from the concave border of the arch of the colon backwards to the spine ; this process is very strong and dense, it encloses the vessels of the colon, and forms a sort of divi- sion or partition in the abdomen, between the epigastric and umbilical regions, the former containing the true digestive organs, the latter those of nutrition ; no communication can take place between these except that through the duodenum, and altogether behind the peritonaeum : when the transverse meso-colon has arrived at the spine, its two la- minae separate, one descends the other ascends ; the descending layer is very strong, expands laterally into the right and left lumbar regions, in each of which it is reflected either partially or perfectly around the ascending and descending colon, and thus forms a short fold or pro- cess very irregular in different subjects, termed the right and left lum- bar mesa-colons ; this inferior, or descending layer of the transverse meso-colon is also continued obliquely downwards in the middle line to form the mesentery, a process which we shall trace when we have pur- sued the superior, or ascending layer of the meso-colon to its termina- tion. This lamina is thin and delicate ; it ascends in front of the in- ferior and middle portions of the duodenum, and of the pancreas ; it also covers the aorta and vena cava, and continues along this latter vessel to the liver, on the Spigelian lobe of which it expands, and on it and on the right lobe, behind the foramen of Winslow, it becomes continuous with the peritonaeum, which has been reflected on the back part of the liver from the diaphragm. As this ascending layer pro- ceeds in front of the pancreas, it is continuous on each side with the posterior layer of the lesser omentuni which covers the back part of the stomach. This ascending layer may be best seen and traced by dividing the great omentuni a little below the stomach, and raising this organ towards the thorax ; we shall thus lay open the cavity of the omentum, and shall be able to trace the parietes of this bag through their whole extent. The cavity or sac of the omentum extends from the transverse fissure of the liver superiorly, to the lower border of the great omentum infe- riorly ; it is bounded anteriorly by the lesser omentum, the stomach, and the anterior or descending portion of the great omentum ; infe- riorly it is formed by the great omentum turning on itself; and pos- teriorly it is bounded by the ascending portion of the great omentum, 236 DUBLIN DISSECTOR. by the colon, by the transverse meso-colon, and by the superior, or ascending, layer of this process, which terminates at -the liver. The cavity of the omentum communicates with the general peritonaeal ca- vity through the foramen of Wlnslow ; this opening is situated in the lower part of the right hypochondriac region, just above the right lumbar ; it is somewhat oval, bounded anteriorly by the lesser omen- tum which encloses the vena porta, and the hepatic duct and artery, posteriorly by the termination of the ascending layer of the meso-colon which invests the vena cava, superiorly by the lobulus caudatus of the liver, and inferiorly by the superior portion of the duodenum. If the membrane composing the omenta be perfect, and if air be forced through this opening, it will descend behind the stomach, and will inflate the omental cavity ; the great omentum, however, in general, is so cribriform that this experiment cannot be performed ; the principal use of this cavity is most probably to afford a serous surface, or cavity for the stomach to move hi, or to distend into posteriorly during the progress of digestion. The splenic omentum extends from the fissure in the spleen to the great end of the stomach, and is continuous with the anterior layer of the great omentum ; the splenic vessels and the vasa brevia are contained between the laminae of this process. The colic omentum is a fold of peritonaeum which descends from the upper part of the right or ascending colon ; it generally lies posterior to the great omentum ; it is composed of two laminae, between which are contained blood-vessels and adipose substance. The right and left lumbar meso-colons are folds connecting the ascending and descending colons in the lumbar regions ; these are usually very imperfect, or open posteriorly, so that the back part of this intestine in each lumbar region is uncovered by peritonaeum, and is connected by cellular tissue to the kidney ; the right colon is usually more uncovered by it on this aspect than the left, and is there also in contact with the duodenum ; both are also connected to the quadratus lumborum muscles. The appendices epiploicce are attached all along the large intestine, but principally to the transverse arch of the colon ; they are small prolongations of the peritonaeum, filled with a soft fatty substance ; they are never found attached to the small intestine ; they vary very much in different subjects in number and size ; their use is not ascer- tained. The mesentery is the largest and most remarkable process of the pe- ritonaeum ; it is continuous with the descending layer of the meso- colon, and extends from the left side of the second lumbar vertebra obliquely downwards to the right iliac fossa ; this is the root of the mesentery ; from this it expands very much, and is folded round the jejunum and ileum intestines, and then returns again to the spine or to the inferior surface of the root ; the laminae of the mesentery can be easily separated ; between them we find the mesenteric arteries, veins, and nerves, also numerous absorbent vessels and glands ; the mesen- IH BUN DISSKCTOK. 237 u-ry serves to support the convolutions of the small intestines and the numerous vessels passing to and from these. The iHcso-cd-cum is a fold of peritonaeum which attaches the ca3cum to the right iliac fossa ; this process, however, is freqently imperfect ; the posterior portion of this intestine being often deprived of a serous coat, and connected to the iliac muscle by cellular membrane. The meso-rectum is a short fold of peritonaeum which connects the superior portion of the rectum to the upper and anterior part of the sacrum ; it encloses the hsemorrboidal vessels and nerves. The peritonaeum covers the abdominal viscera in a very unequal manner, that is, some only partially or imperfectly, others almost en- tirely ; no viscus can be wholly enveloped by it, as in every case some part must be free for the entrance and exit of its vessels, as these never perforate the membrane. The spleen, and the jejunum and ileuni intestines, are among the most perfectly enclosed organs, as the perito- neum is unadherent only along the concave aspect of each, where the vessels and nerves are placed ; next hi degree are the stomach and the transverse colon, on each of these the membrane is unconnected along the convex as well as the concave aspect ; on the liver also it is unattached at the great transverse fissure where the blood-vessels and nerves enter, and partially also along the convex or diaphragmatic border, where the veins escape from this organ ; the gall bladder also is only partially covered by it, as it attaches tin's viscus to the liver, but does not pass between them; the right and left colons very gene- rally want this coat posteriorly ; the middle and inferior divisions of the duodenum are but loosely covered by it in front, and no part of tlit> very termination of this intestine is attached to it, as the fasciculus of the superior mesenteric vessels is interposed ; the lower portion of the rectum is in the same predicament ; the urinary bladder, the pan- creas, and kidneys are all but imperfectly covered by it ; these facts are of some practical importance, and will be more particularly set forth in the description of the individual organs. The peritonaeum effects several useful purposes : first, it enters more or less into the structure of the several viscera, and in some it serves as an important 1 ihysical element ; second, it assists in retaining the organs in a certain position, and in maintaining their different relations ; third, it conducts the numerous vessels and nerves ; fourth, it strengthens the walls of the abdomen, by adhering to and connecting together the muscular fasciculi of which they are chiefly composed ; and lastly, by the exha- lation of a lubricating fluid, it allows opposed surfaces to glide on each other without any sensible friction, it thereby facilitates the ac- tions of the parietal muscles on the contained viscera, as well as the movements of the latter among one another. Tlu- peritonaeum is composed of the same elements as other serous membranes, namely, an external lamina which is similar to cellular or areolar tissue, containing the nutrient or functional vessels and nerves, and connected to the surrounding structure; and an internal layer, which Is .smooth, dense, and pearly, which appearance is sup- 238 DUBLIN DISSECTOR. posed to depend on the existence of a fine epithelium composed of in- numerable lamina? of flattened vesicles with central nuclei. The viscera contained in the abdomen are the digestive and urinary organs ; the former we shall examine first. The digestive appai'atus pre- sents a series of connected or continuous organs, each of which is con- cerned in some especial manner in effecting certain changes on the food, whereby it becomes fit for the nutrition of the system. The term " diges- tion" is commonly confined to the operation of the stomach; but it should be more extensively applied, so as to include the successive changes which the food undergoes from its reception into the mouth until it is sepa- rated in the small intestines into the nutritive portion or chyle, which is there absorbed by the lacteals, and into the residuum, which is discharged by the large intestine. Indeed, in a physiological sense, the term might be still further extended, as the chyle, most probably, is not fully elaborated for nutrition until it has been duly mingled with the blood by the circulation of the latter, and along with it purified by the respiratory process. This function, then, properly includes the processes of mastication, insalivation, and deglutition, which last con- veys the food into the stomach, where the next and decidedly the most interesting change takes place, that is chymification. In the duode- num chylification occurs ; in the jejunum and ileum the chyme is sepa- rated and absorbed ; and lastly the large intestine retains the resi- duum for convenience, and finally expels it from the body. The whole apparatus is one long canal, extending from the mouth to the anus, lined by mucous membrane or integument, which is continuous at either end with the general integument of the body. This tube pre- sents various shades as to organization and physical characters in dif- ferent situations ; it is throughout generally well supplied with vessels and nerves, although, except in some situations, it presents but few traces of sensibility, at least in the ordinary sense of that term ; it is covered throughout by lamina} of muscular fibres, which are eminently involuntary, excepting towards either extremity, where voluntary power, for obvious reasons, has been endowed : varied secretions are poured forth upon its surface, some from the folds and follicles which form part of its structure, others more elaborate are derived from organs at a distance, furnished with excretory ducts for the ^purpose of supply ; indeed the greater portion of tlu's tissue may be regarded as an expanded glandular membrane. The length of this canal is very considerable ; it is uncertain, but probably about seven times that of the height of the body ; it traverses the lower part of the face, the neck, and chest, is greatly complicated and extended in the abdomen, which it nearly occupies, also a great portion of the pelvis, and finally terminates in the anus, in front of the coccyx ; in the neck it is in con- nexion with the respiratory, and in the pelvis, but not so intimately, with the geni to-urinary apparatus. We have already examined the organs concerned in mastication, insalivation, and deglutition ; we shall now proceed to that important and more voluminous portion of this appai'atus which occupies the abdominal and a portion of the pelvic 239 * The alimentary canal laid open from the lower extremity of the oesophagus to the rectum. 6. The oesophagus. 7. The internal surface of the oesophagus. 8. The cardiac or cesophageal orifice of the stomach. 9. The internal surface - of the stomach. 10. The left or splenic extremity. 11. The right or pyloric extremity. 12. The lesser curvature of the stomach. 13. The greater curvature. 14. The pylorus. 15. The superior transverse portion of the duodenum. 16. The middle or perpendicular portion. 17. The inferior transverse portion. 18. The gall-bladder. ]!>. The cystic duct. 20. The hepatic duct. 21. The ductus com- numis cholcdochus. >." Its aperture in the duodenum. 23. The duct of the pancreas dissected from the gland ; its aperture in the duodenum is seen close to that of the ductus choledochus. 24. The commencement of the jejunum. 25. 25. The jejunum. '_'(!. 2C. The ileum. 27. Theileum opening into the great intes- tine. 28. The ileo-colic valve. 2. The : ileo-caral \alve.' :>0. The cavity of the ravum. -I. The appendix vermifonnis. M2. The ascending or right lumbar colon. ;;:{. The transverse arch of the colon. 34. The left or descending colon, ::">. The sigmoid tiexure of the colon. o<;. The rectum. :;". The anus. 240 DUBLIN DISSECTOR. cavity ; it is composed of several viscera, which may be divided into the membranous or hollow, and the glandular or solid. The membranous viscera are the stomach and intestinal tube : the latter is divided into the small and large intestine : the small intestine is subdivided into the duodenum, jejunum, and ileum ; the large intestine into the caecum, colon, and rectum. The glandular viscera are the liver, spleen, and pancreas. We shall consider the membranous viscera first, and com- mence with the description of the stomach, which is the most impor- tant part of the apparatus, the principal change of the food being accomplished in this organ. The stomach is the most dilated portion of the alimentary canal ; its capacity is very variable, depending in part upon the degree of disten- sion or contraction before death ; it is placed between the oesophagus and the duodenum, and communicates with both ; it is situated in the left hypochondriac and epigastric regions, and a small portion of it extends into the right hypochondrium : from the left side it passes across the epigastric region, obliquely downwards and forwards, and near its right or pyloric extremity it bends a little upwards and back- wards. It is connected to the diaphragm by the oesophagus and by the peritonaeum ; to the spleen by the splenic omentum and vasa brevia ; to the liver by the lesser omentum ; and to the arch of the colon by the great omentum : it is, therefore, nearly a fixed viscus, and not liable to displacement, although it has been found drawn downwards in old and very large umbilical herniae, also in cases of enlarged spleen. If the stomach be moderately distended with air or fluid, its form and connexions can be better understood ; it will then appear somewhat of a conical figure, the base to the left side, the apex to the right, the intermediate part being somewhat curved ; it will then also present two extremities, the left and right ; two orifices, the cardiac and pyloric ; two surfaces, an anterior or superior, a posterior or inferior ; and two curvatures or edges, the lesser or concave, the greater or convex. The left or splenic extremity is very large (great cul desac^, swells into the left hypochondrium beneath the ribs, so as nearly to conceal the spleen. The right or pyloric extremity is much smaller, is cylindrical and slightly convoluted like an intestine : it lies anterior and inferior to the left or splenic end, and extends to the fundus of the gall bladder or to the edge of the lobulus quadratus of the liver ; it sometimes descends into the umbilical region ; it forms the apex of the general cone, and is distinguished from the duodenum by the circular contraction of the pylorus, a little to the left of which the stomach is often found somewhat dilated towards the convex border, into a sort of sinus or cul de sac (antrum pylori) : sometimes also there is a smaller dilatation, nearly opposite to this, on the lesser curvature. The cardiac or cesophageal orifice is the highest point of the stomach ; it is situated between the left or great end and the lesser curvature, about three inches distant from the former ; it is surrounded by vessels and nerves, and is connected to the diaphragm by the peritonaeum. The pyloric orifice is between the stomach and the duodenum ; it lies to the right IH'IJI.IX IHSSKOTOR. _>-! 1 side of the spine ; it is moveable to a certain extent, its position is theiv- fure variaMe ; in general it is in contact with the liver and gall bladder, and is anterior to the pancreas and to the right epip- loic artery ; it is inferior, anterior, and to the right side of the cardiac orifice, has a peculiar firm, hard feel, and a constricted appearance. The angles at the cardiac and pyloric orifices are diflerently affected according as the organ is contracted or dis- tended ; in the former state there is no angle between the oeso- phagus and the stomach, whereas in the latter it may become even an acute one ; the contrary is the case at the pyloric, during the empty state of the stomach this forms with the duodenum an acute angle, convex above ; while, in the distended condition, the pylorus leads backwards and downwards into the duodenum : these altera- tions, in the form and aspect of these orifices, are in conformity with their respective functions. The anterior surface is below the xiphoid cartilage ; it looks upwards and forwards, and is hi contact with the diaphragm, the ribs, and the left lobe of the liver, and, when dis- tended, with the abdominal parietes. The posterior surface looks backwards and downwards ; it forms the front of the bag of the omen- turn, the cavity of which separates it from the meso-colon, pancreas, and duodenum. The lesser, or concave edge, looks backwards and upwards towards the spine and lobulus Spigelii of the liver ; this edge, near the pylorus, is convex, the great edge being concave opposite to this ; the lesser omentum is attached to it, and the coronary vessels run along it. The great or convex edge looks forwards and down- wards towards the colon ; to it the great omentum and the epiploic vessels are attached, and occasionally some lymphatic glands : in the empty or contracted state these edges are thin, and directed almost vertically, but when distended, they become enlarged and round, and continuous with the surfaces ; the convex edge is then directed for- wards as well as downwards towards the abdominal muscles, and the concave edge backwards and upwards towards the aorta and the spine. The stomach is composed of three proper tunica a serous, a mus- cular, and a mucous : these are connected to each other by laminae of cellular membrane, which are regarded by some as the common tunics. The serous or peritoneal coat is derived, as was before explained, from the laminae of the lesser omentum, separating at the lesser curvature, expanding over the surfaces, and uniting along the convex edge to form the great omentum; it is loosely united to the edges, but almost inseparably to the middle of each surface and to the pyloric extremity ; along each edge or curvature a triangular space is left, to which this membrane does not adhere ; that along the convex border is much the wider ; these spaces are enlarged during the distension of the organ, and facilitate its expansion ; whereas, if the peritonaeum adhered in these situations as closely as to the sur- faces, its want of extensibility would interfere with the sudden enlargement of the stomach. These spaces also afford a suitable enclo- sure for the blood-vessels ; the coronary being contained in that along T, and the epiploic in that along the greater curvature. A 242 DUBLIN DISSECTOR. layer of very fine subserous or cellular tissue connects this to the fol- lowing tunic, the muscular ; this consists of fibres which run in three different directions ; the first or superficial are longitudinal ; they art: continued from the longitudinal fibres of the oesophagus, arc radiated and scattered over its surfaces, and are very strong along the curva- tures, particularly on the lesser, the form of which they retain ; some fibrous bands usually run superficial to these in the subserous tissue ; these fibres are very strong near the pylorus ; some end in its constric- tion, and others are continued on the duodenum. The middle layer of fibres run circularly ; they commence at the left extremity, or cul de sac, and are arranged in nearly pai-allel rings ; they are weak and few on the left end, but very strong to the right of the centre, where they often cause a constricted appearance around the stomach, as if dividing it into two portions. The circular fibres again increase in thickness as they approach the pylorus, the sphincter of which they form : these fibres do not form perfect circles, the extremities of each fasciculus turn obliquely to one side. The third set of fibres take a very irregu- lar or oblique direction ; they are most distinct on the great end, or cul de sac, and appear as a continuation of the circular fibres of the O3sophagus, and run in loops or arches nearly parallel to the long axis of the stomach. The muscular coat of the stomach is very variable as to colour and development ; it is usually pale, sometimes almost white and semi-transparent ; along the curvatures, particularly the lesser, it is often not only strong, but very red, and sometimes contains a fibrous or tendinous band; it is always thin over the splenic end, or cul de sac, and much thicker at and near the pylorus ; in general its strength is in an inverse ratio to the size or capacity of the organ. These several planes of fibres do not form so many distinct layers, but rather inter- lace, so as to form more or less of an areolar muscular tissue ; the areolse are large in the distended condition of the organ. Beneath the muscular tunic is the second lamina of cellular tissue, which contains the minute divisions of the nerves and vessels of the stomach, and has been, by some, called the nervous coat of the stomach. This coat is connected to the muscular by numerous pi-ocesses or septa, and to the mucous by cellular tissue, vessels, and nerves ; it is composed of a dense net- work of filaments and lamina?, which possesses considerable strength, so as to resist distension in the muscular areolze. This tunic may be examined either by removing the serous and muscular, or, when the stomach has been everted, by raising a portion of the mucous mem- brane ; in the fine cellular tissue, which connects this to the mucous or lining coat, is contained the net-work of capillary vessels for the supply of the latter : it gives support to the mucous membrane, and forms, as it were, the frame-work of the organ ; and, therefore, some anatomists consider this tunic as the deep layer of the mucous mem- brane, and do not enumerate it among the distinct coats of the sto- mach. The internal or mucous coat, also called villous, from its soft, velvet-like appearance, is continuous with that lining the oesophagus and duodenum. In order to examine it the stomach should be re- moved from the subject, everted, or opened longitudinally, and washed N nissrx 101:. 24.'? under a gentle stream of water, as it is usually covered with viscid, adhesive, mucous and alimentary matters. It presents, it' recent and normal, a pale pink or rosy tint ; but the shade of colour is very varia- ble, and depends on many circumstances : in cases of sudden death, and the organ empty, it has been found of a pale red, but, if digestion had been in progress, of a more vivid tint ; if some days have elapsed between death and examination, it often presents brown or black patches, chiefly in the splenic end and around the large blood-vessels ; such patches are often soft, pulpy, and decomposed, and may be the effects of transudation of blood, or of putrefaction, or of solution by the gastric fluid. The shade of colour may also depend on the pre- vious state of the organ, as to health or disease ; on its state at the time of death, whether full or empty ; and if in the former, on the nature of its contents, and the influence of the gastric fluid upon the latter; also on the presence of bile, &c. This membrane is always thrown into folds or rugae, of which there are different species ; the most prominent and numerous are nearly parallel to the long axis of the organ ; some bend off tortuously from this direction ; these rugae are most distinct in the pyloric portion ; they are obviously designed to admit of the rapid and easy distension of the stomach, particularly in the circular direction ; the mucous tissue alone enters them ; they have no analogy to the permanent mucous folds, or valvulae conni- ventes, in the intestinal tube ; these folds are intersected here and there by others, so as to give rise te an areolated appearance ; these will facilitate longitudinal enlargement. If a recent and contracted sto- mach be filled with and immersed in spirits for some days, and then a portion of its anterior wall removed, the form of the organ and these several rugae are well preserved. At the cardiac orifice the lining membrane is plicated longitudinally, and somewhat festooned, the borders being marked by a slight projection, which in some cases is very abrupt and very distinctly marked ; but not so in others, indeed it seldom equals the representations hi the engravings of this part : these plicae chiefly consist of the epithelium continued from the oeso- phagus, where it is white, firm, and scaly, like epidermis ; whereas in the stomach beyond this it becomes soft, thin, and of a pink or reddish tint. Corresponding to the pylorus is a remarkable circular fold, with a small aperture in the centre (pyloric valve) ; this fold is encircled by a strong band of sphincter fibres, upon which its valvular powers depend, as it has none such in the dead body ; during life, when the sphincter acts, it can close the opening between the stomach and the intestine, and prevent the passage of any matter equally from one into the other. The mucous membrane, on its gastric surface, differs in organization from that on the duodenal aspect, being thicker and more follicular. If a stomach and duodenum be filled with air and dried, and in the course of a few days the pylorus with about two inches of the canal on either side removed, a very useful preparation of this valve is made; its circular, partition-like form and central aper- tnre are well seen, and bear some analog}' to the iris and the pupil, R2 244 DUBLIX DISSECTOR. This coat of the stomach is soft and thin, easily broken and detached, especially from the splenic end, where it is often found pulpy, and breaks off in shreds ; in the pyloric portion it is thicker and stronger, and can be dissected entire from the other coats : however, these as well as other physical characters, much depend on the general condi- tion of the organ and the length of time elapsed since death. Occa- sionally, in a very recent stomach, we may observe a marked line of distinction in the organization of the mucous membrane in the splenic and pyloric portions ; this line will correspond to the circular constric- tion caused by the muscular fibres, thus shewing some approximation to the bilocular or compound multiple stomach of many inferior animals. This membrane sometimes presents a peculiar granular appearance ; I have observed this more frequently along the lesser curvature, also near the pylorus ; it probably depends on an hypertro- phied state of the mucous glands and follicles. When the surface of this membrane is cleared of all adherent mucus, different portions of it may be removed and examined, some with a magnifying lens through a thin stratum of water, others floating in fluid beneath a glass globe, and others extended on thin plates of glass ; the surface will be found to be very irregular, though so soft and smooth to the feel. Numerous follicular papilla), but not true villi, project, and leave between them small depressions or pits studded with minute holes ; these pits are more or less circular, and are bounded and sepa- rated by the follicular elevations ; they are most distinct towards the pyloric portion of the stomach ; four or five foramina are seen in each ; these are the orifices of the small glands and ducts that elaborate the gastric fluid, the mucus probably being furnished by the follicles. If the cut margin of the membrane be examined, it will be found chiefly composed of tubes closely applied to each other, their caeca! ends lodged in the submucous tissue, and their open extremities are these small holes in the pits or alveoli on the surface of the membrane ; some are short and straight, others are longer, convoluted, and par- tially dilated ; bloqd- vessels pass between these, and cover them with a vascular net- work. Much of our information as to the characters of this membrane during life, as well as of the process of digestion, has been accidentally derived from that interesting case of Martin, noticed and recorded by Beaumont, and published by Coombe. In this case" a wound had divided the abdominal parietes and opened the stomach ; a fistulous passage formed leading into its cavity, and the general health having recovered, an opportunity was thus obtained for the inspection of this membrane, and for the examination of many of the phenomena of di- gestion. The following facts are recorded : " The inner coat, in its natural state, is of a light or pale pink colour, varying in hue according to its full or empty state, of a soft, velvet-like appearance, and constantly covered with a thin, transparent, viscid mucus. When aliment or any irritant is applied to the surface, innumerable lucid points and fine nervous or vascular papillae can be seen arising DUBLIN DISSECTOR. 245 through the mucous coat, from which distils a pure, limpid, colour- It's-, slightly viscid fluid. This is invariably acid. The mucous of tlx- stomach is less fluid, more viscid, semiopaque, a little saltish, and luts no acidity. The gastric fluid is never accumulated while fasting, and is seldom, if ever, discharged except under the excitement of food or other irritation; it is secreted only in proportion to the quantity of food supplied, provided there is not more of the latter than the system requires ; and, if an excess of food be taken, the residue either remains in the stomach, or passes into the bowels in a crude state, and gives ri>e to nervous irritation, pain, and disease. In disease or partial derangement of the healthy function of this membrane, it presents various appearances ; in febrile conditions, from any cause, it some- times becomes red and dry, at other times pale and moist, and the secretions vitiated: scarcely any mucus, and the follicles flat and flaccid; sometimes it presents an appearance of eruptions, pimples here and there, sharp and red, and often filled with white purulent fluid, red patches, aphthous crusts, and abrasions of the surface ; these are usually accompanied by dryness of the mouth and tongue, thirst and fever, and, when the healthy state of the stomach is restored, the tongue becomes clean and natural." We shall revert to the minute structure of this membrane when we have examined the remainder of the ali- mentary canal, and shall then also contrast it in different situations. The stomach is very freely supplied with blood from the caeliac axis; the coronary and epiploic arteries, with the vasa brevia, enclose it in a sort of net-work of inosculations. During its distension the trunks of the two former arteries are extended close to the organ, along its curvatures, but, when empty, they are removed to some distance from it, and are then flaccid and coiled. The veins are numerous and large, and join the portal system. The eighth nerve of the left side expands on the anterior, and that of the right side on the posterior surface : both form a plexus around the cardiac orifice, and appear to be chiefly distributed to the muscular tunic. From the solar plexus of the sympathetic numerous nerves are also derived ; these accompany the arteries, are supported by them, and penetrate the submucous tissue' as far as the eye can trace them. The stomach is not provided with lacteals, at least but very sparingly ; absorption of fluids, how- ever, rapidly takes place in it, and is effected through the medium of the venous capillaries by endosmose. The mucous coat of the stomach secretes the fluid called the gastric juice or acid, which is generally believed to have the remarkable properties of being powerfully solvent and anti-putrescent. In the stomach the food undergoes the first important change in digestion, being here converted into a soft, homo- geneous, pulpy mass, called chyme. To effect this important change, and which appears to be essentially chemical, the food must remain enclosed in the stomach for some time, varying as to the nature and quantity of the mass, as well as the condition of the organ and of the general health ; a gentle contraction, as well as the elasticity of the structures at the cardiac and pyloric orifices, are sufficient to retain it. 246 DUBLIN DISSECTOR. As each superficial stratum is digested, it is moved on by the gentle peristaltic action of the muscular coat, and transmitted through the pylorus, the sensible and irritable endowments of which are such as to oppose, at least for a considerable period, the transit of any large or undigested substance. Beaumont has observed, "that the food entering the stomach from the oesophagus, in successive waves, is sub- jected to a peculiar peristaltic action, which effects an intermixture of the gastric fluid with the alimentary mass, and aids the solution of the latter by gentle trituration. The stomach is also constantly agitated by the respiratory movements. The food, after passing the oesopha- geal orifice, moves from right to left along the small arch, then from left to right along the large curvature, and then returns and performs similar revolutions; a revolution occupies from one to three minutes; they are slower at first than after chymifica- tion has advanced, when there is also an increased impiilse towards the pylorus. It is probable that portions of chyme are constantly passing into the duodenum, as the alimentary mass progressively diminishes in bulk. This accelerated impulse appears to be effected by that portion of the circular fibres which embraces the organ about four inches from the pylorus, and which, in the latter part of the pro- cess, is found so constricted as almost to separate the two portions in an hour-glass form, so that, in introducing a long thermometer, the bulb was at first resisted, then allowed to pass, and then grasped and drawn in. Hence it is evident that this contraction tends to resist the passage of any solid matter into the pyloric portion of the stomach, while the fluid parts readily escape : these peculiar motions continue until the stomach becomes perfectly empty." The duodenum is the next portion of the alimentary canal ; it is so named from its length (which is from eight to nine inches), being equal to about twelve fingers' breadth : this is the first and shortest, but most dilatable division of the small intestine ; it extends from the pylorus to the root of the mesentery, where the jejunum commences ; it lies partly in the right hypochondriac and partly in the right lumbar and umbilical regions ; the greater portion of it is deep- seated, and surrounded by cellular and adipose tissue ; it takes a semi- circular course around the head of the pancreas, convex to the right side. This course may be divided into three parts : the first, or supe- rior transverse ; the second, or perpendicular ; and the third, or inferior transverse. The superior transverse portion ascends from the pylorus obliquely backwards and to the right side, beneath the edge of the liver, so as to touch the gall-bladder. Here the intestine makes a sudden or acute turn (the superior angle), and the middle or perpen- dicular portion of it commences ; this descends in front of the right kidney, as low as the third lumbar vertebra, where it makes a second turn (the inferior angle), from which the inferior transverse portion extends obliquely upwards across the spine ; and at the left side of the first or second lumbar vertebra ends in the jejunum. The duodenum differs so materially in function and structure from the remainder of 2-17 tin- small intestine as to have been regarded by .some as a second .sto- mach ; it is fixed in its situation, being only partially covered by the peritoneum, and is of much larger calibre, particularly near the interior angle ; it can never be protruded in hernia ; its muscular coat is very strong, and the valvuhe conniventes very numerous and large. The superior transverse portion, about two inches in length, is more contracted than any other part of it, and is covered on both surfaces by the peritonaeum, like the stomach, and is, there- fore, more moveable than the rest of the intestine. The perpendicular portion is concealed by the omentnra and by the colon, and is covered by the ascending layer of the meso-colon ; this portion lies on the right kidney, vena cava, and ductus choledochus, and has no perito- neum posterior to it ; it is, therefore, fixed, and is dilatable ; it is above three inches long. The biliary and pancreatic ducts perforate the inner side of this division of the duodenum ; these pass through its coats very obliquely, and open into the intestine, sometimes dis- tinctly and at other times conjointly, on a small papilla, opposite the inferior angle ; and hence the necessity for this intestine being fixed. The inferior transverse part of the duodenum passes across the spine, the right crus of the diaphragm, the aorta, and the right renal ves- sels ; like the middle portion, it is only partially covered by the peri- toiueum, being placed between the layers of the meso-colon ; the sac of the omentum separates it from the back of the stomach. Its lower border maybe seen, without dissection, projecting through the inferior layer of the meso- colon ; its upper border adheres to the pancreas, except where the superior mesenteric vessels intervene ; these pass in front of the termination of this part of the duodenum, and appear to compress it against the aorta, so as to retard the passage of its con- tents into the jejunum; a marked line or angle of distinction is thus made externally between the duodenum and jejunum, but internally no definite line is to be observed. The arteries of the duodenum are derived from the hepatic, splenic, and superior mesenteric ; the veins join the porta, and the nerves are from the solar plexus. In the duodenum the process of digestion is completed; the chyme is mixed with the biliary and pancreatic fluids, and a separation takes place between the chyle and the excrementitious part of the food. We shall consider the structure of this intestine presently. The />/' nnn m and ilcum intestines are partially concealed by the Amentum. If we raise this process and the arch of the colon," and place them on the edge of the thorax, the convolutions of these intes- tines will be seen in the umbilical, hypogastric, and iliac regions, convex anteriorly, concave posteriorly, and attached to the mesen- tery : the jejunum commences in the left lumbar, and the ileum ends in the right iliac region. There is no exact division between these two intestines; the upper two-fifths are named the jejunum, and are placed higher in the abdomen than the ileum, which is the name given to the three remaining fifths ; the former is redder, feels thicker, and is larger than the latter, which is pale and thin. These 248 DUBLIN DISSECTOR. differences are striking when we compare the commencement of the jejunum with the terminating portion of the ileum; in the interme- diate space, however, they are gradually lost ; they depend on the greater vascularity and number of valvulae conniventes in the first than in the second, but there is certainly no accurate anatomical reason for this division. From the duodenum the jejunum first passes for- wards and to the left side ; it then descends into the middle of the ab- domen, is folded upon itself over and over again, and extends into different regions, and, finally, the terminating portion of the ileum rises out of the pelvis from left to right, and joins the caecum at an acute angle convex upwards. The general direction of the canal is from the left side downwards and to the right, and its dimensions de- crease in this course, though the ileum is often dilated near its entrance into the caecum. The distance between the commencement of the jejunum and the end of the ileum is not more than five or six inches ; yet, if the coils of the tube be unfolded, it may be extended to fifteen, or even twenty feet. The length of the canal, however, cannot be accurately determined ; if detached from the body, flaccid and extended, it will measure longer than if distended and in situ ; it does not bear any uniform ratio to the height of the individual, but usually it is three or four times as long. The mesentery being broader in the centre than at its extremities, supports the numerous convolutions in a wonderful manner, free from any entanglement, compression, or obstruction, and though to a certain degree retained in their position, yet they enjoy considerable mobility; this, together with the yielding tissue of which they are composed, allow them to mould themselves to the adjacent parts, and to accommodate themselves to every alteration induced by change of position or by muscular action. At the same time, how- ever, this mobility, which is greater in some convolutions than in others, admits of the frequent occurrence of hernia, as also of intus- susceptio or imagination. Each convolution is curved into more than a semicircle, convex forwards, concave towards the mesentery, but the size and figure of each is constantly varying. These intestines are in contact with the abdominal parietes, except where the omentum intervenes, and they are separated from the spleen, stomach, and liver by the transverse colon and meso-colon ; the large intestine encircles them ; the arch of the colon is anterior, but the right and left colons and the rectum are behind them. Several coils occupy the peritonaea! cul de sac in the pelvis, between the bladder and rectum in the male, and before and behind the uterus in the female. To the ileum, near the lower end, a small digital appendix or diver ticulum is occasionally found attached, the embryonic remnant of the vitelline sac. The form of the small intestine is nearly circular, but a little concave posteriorly where the mesentery is attached, and where there is a small triangular space in which the peritonaeum does not adhere ; this loose cellular space facilitates the distension of the intestine and encloses its vessels and nerves. We shall consider the structure presently. The large intestine, from four to five feet long, forms about one-fifth '240 of the canal ; is divided into civcuin, colon, and rectum ; it differs from tlir s^niall not merely in size, but in being cellular or sacculated when distended ; small processes also (appendices epiploicaj) are attached to it; three strong, longitudinal, muscular bands may also be observed, chiefly in the caecum and colon, and appear to pucker it, and so cause the cellular appearance ; these bands also possess much elasticity, and in some animals are decidedly elastic. The large intestine is pale and thin, and has but few valvula; conniventes ; it extends from the right iliac region to the anus, encircling the convolutions of the small intes- tine ; in some situations it is superficial, in others deep-seated ; a por- tion of it is found in every region of the abdomen ; from the right iliac it ascends through the lumbar into the right hypochondriac, then tra- verses the epigastric and the umbilical tortuously ; it next sinks into the left hypochondriac, descends through the lumbar into the left iliac, and finally sinks through the hypogastric into the pelvis ; its lumbar portions are fixed, but its transverse arch and left iliac coils are very moveable. Its size is variable, though in general larger than the small intestine, yet it is often found in the child contracted into a cord-like form, while in the adult and aged it is sometimes dilated and distended with air to a surprising extent. The caecum is the largest part ; from this it gradually decreases until within about two inches of the anus, where it is usually expanded previous to the con- tracted anal opening. The caecum, or caput coli, is a cut de sac in the right iliac fossa, which it nearly fills, fixed by the peritonaeum, which in general covers it only inferiorly, anteriorly, and laterally, while cellular membrane connects it posteriorly to the iliac and psoas muscles and iliac fascia : in some, however, the peritonaeum covers it all round, and connects it so loosely by a meso-caecum that it may escape in hernia ; it is co- vered by the abdominal muscles, and sometimes partially by the coils of the ileum ; it lies beneath the kidney, and is continuous with the ileum and the colon ; is somewhat triangular, the apex below, and directed inwards to the left side ; the base above, and somewhat to the right, joins the colon at an obtuse angle, convex outwards ; there is no exact limit between them ; on its external surface are three irregu- lar protuberances, one anteriorly and two posteriorly. The appendix rermiforinis proceeds from the left side of its lower and posterior part ; this is a small, tortuous, tubular cul de sac, about the size of a goose- quill : it falls over the brim of the pelvis, and communicates with the caecum, just below the ileum, by a semi- valvular opening ; a mesen- tery connects it in its situation ; variable as to size and length, in some only an inch long, or less, in others five or six, its position also varies, being sometimes turned up behind the caecum ; it has been also found in inguinal and femoral hernia, and it has even caused an inter- nal strangulation, by having become twisted round a convolution of the ileum. Its use is not ascertained ; it may be regarded as an arrest of development, or rudiment of the more highly developed caecum of other animals. Before birth it proceeds from the lower end of the ra-mm, and appears like its contracted, tapering end, from which the 250 DUBLIN DISSECTOR. longitudinal bands proceed ; but as the caecum enlarges it bulges for- wards and downwards, while the appendix assumes the appearance of an offset directed inwards and backwards towards the pelvis. The ileum joins the left or inner side of the caecum at an acute angle, it appears to perforate it, the peritonaeum and external muscular fibres of the ileum being continued into the corresponding parietes of the caecum, -while the circular fibres and mucous coat of the ileum pro- trude into the caecum to form valves, as may be seen by opening the latter in a perpendicular dh'ection on the opposite, that is, on the right side, and washing out its contents. We then perceive the open- ing of the ileum, narrow, like a transverse or button-hole slit, look- ing obliquely downwards and outwards towards the right os ilii, and protected by two semilunar folds of mucous membrane, which enclose a few muscular fibres. These valves should be examined both in the recent state, in situ, or removed and floated in water, or in a dry, dis- tended preparation. The inferior, or ileo-cacal valve, is the larger, is somewhat vertical, it secures the ileum against regurgitation from the caecum ; the superior or ileo-colic valve is smaller, and rather ho- rizontal, it secures the ileum against regurgitation from the colon ; these are united at their extremities (commissures), and from each commis- sure a fold is continued round on the inner side of the cae- fig. 46.* cum, these are the fruena or re- tinacula of the valves, through the medium of which, and of the commissures, the distension of the caecum closes the ileo- caecal foramen. Each valve is composed of two laminae of mucous membrane, enclosing cellular tissue and a few mus- cular fibres ; the iliac surface of each differs in organization from the caecal. These valves are unlike that of the pylorus, or the valvulae conniventes ; in the dead body their valvular powers vary ; I have some- times been unable to force even air through them from the caecum or colon, but in other cases they have offered but little resistance ; they appear perfectly adequate to oppose the reflux of any solid or consistent substance, and they are certainly more effective in a recent specimen than in one long dead. The caecum is provided with the same longitudinal bands and appen- * The termination of the ileum and the commencement of the large intestine. 1. Portion of the, right or ascending colon. >. The cajcum or caput coli. 3. Portion of the ileum. 4. The ileo-colic valve. 5. The ileo-caecal valve. 6. C. Muscular coat, the peritonaeum having been removed. 7. 7. Submucous and mucous coats, forming folds. i>issi;< TOK. '251 il it-os epiplok-ic. and invents the same sacculatcd appearance as the colon : it has no valvular conniventes. The colon extends from the eiccuin to the rectum : it is divided into four portions, the right or ascending, the middle or transverse arch, the left or descending, and the sigmoid flexure ; there is, however, no mark of distinction what- ever as to structure between these different divisions. The ascending colon extends from the caecum to the inferior sur- face of the right lobe of the liver, which it marks with a superficial depression. This portion of thfll colon is concave anteriorly, and covered by the peritona-um and by the abdominal muscles; it lies on the right kidney and quadratus lumborum muscle ; the duodenum and p-nas muscle are connected to it internally ; the superior extremity is generally tinged with bile, from being in contact with the gall blad- der : it is fixed by the peritonaeum, which only passes in front of it, though occasionally it extends round it and forms the right lumbar meso- colon; the convolutions of the small intestines separate it from the abdominal parietes. The transverse, arch of the colon turns off at a right angle from the last, and extends tortuously from the gall bladder in the right hypo- chondrium across the inferior part of the epigastric and the umbilical region, as far as the spleen, in the left hypochondrium ; it is covered by the abdominal muscles and the great omentum, and lies anterior to the small intestines : on the right side it is connected to the liver, in the middle to the stomach and to the great omentum ; and its left ex- tremity, which is superior and posterior to the right, is attached to the spleen by the peritonaeum ; it is very moveable, is sometimes close to the stomach in the epigastrium ; at other times it lies in the umbi- lical, and even descends into the hypogastric region, and is therefore frequently protruded in hernia ; the convexity of the arch is directed forwards, and the concavity backwards, but its course is often so ser- pentine that the term " arch" is not very applicable. It is supported by the transverse meso-colon, which is attached to its posterior con- cavity ; the two lamina; of the great omentum descend in front of it Avithout adhering to it, but when these have ascended they are attached to its anterior border, and then separate to enclose this intes- tine in their progress to become the meso-colon. The appendices epiploicoe are very numerous on this part of the colon. The left or descending colon extends from the spleen to the iliac region, behind the small intestines, is longer than the right, and deeper seated ; it is connected posteriorly to the kidney and to the quadratus lumborum and psoas muscles by cellular tissue ; the peritonaeum covers it only in front ; from this circumstance, and from its proximity to the rectum, it has been selected as the most suitable situation for making an artificial anus, in case of obstruction in the rectum. The anatomi- cal relations of the right colon, with respect to the peritonaeum, are equallv favourable, if not more so, for such an operation. In some cases, on the left side, as upon the right, the peritonaeum envelopes this intestine, and forms a fold called "left meso-colon;" if the intestine 252 DUBLIN DISSECTOR. be contracted, this is more distinct, but, if the former be distended, the latter becomes expanded, and the intestine bulges posteriorly between its layers, so as to be uncovered by the peritonaeum, and therefore more eligible for puncture. The sigmoid flexure is connected so loosely in the iliac fossa that a great portion of it often lies in the pelvis : this part of the colon is par- tially covered by the small intestines, and connected to the psoas and iliac muscles, to the ureter and spermatic vessels ; it is surrounded by peritonaeum, which forms a loose fold (the iliac mcso-colon) of very variable extent : this fold is often so loose that this part of the colon is as free and floating as the small intestines ; it may, therefore, be found in other regions of the abdomen and in the pelvis, and may also protrude in hernia. It first passes upwards in front of the left colon, then descending it forms two or more coils, and joins the rectum opposite the left ilio-sacral symphysis, but without any precise dis- tinction ; its size as well as length vary considerably ; it usually occupies the greater portion of the iliac fossa, and, if distended, can be felt and examined during life through the abdominal parietes. The rectum, or straight intestine, extends from the sigmoid flexure of the colon to the anus ; it commences opposite the left ilio-sacral articulation, and descends obliquely towards the middle line as far as the lower end of the sacrum ; it then bends forwards towards the periuaeum, and lastly, turning a little backwards and downwards, it ends at the anus an inch or an inch and a half from the coccyx ; its course, therefore, is not straight, but curved both in the lateral and antero-posterior direction. As to the former, it commences opposite the left ilio-sacral symphisis, and descends obliquely to the median line as far as the middle of the sacrum, and then continues in that line to the anus. Tin's course, however, is variable ; it not unfre- quently happens that the rectum commences opposite the right side of the base of the sacrum, and descends obliquely to the left ; the antero- posterior curvature is double, the first or superior is concave forwards, is long and gradual ; the second, or inferior, is short and convex for - wards, and is in relation to the parts in the perineum rather than to those in the pelvis ; by this latter curvature backwards it separates from the urethra in the male, and from the vagina in the female. These points, however, cannot be fully ascertained until the dissection of the pelvis and perinaeum; in the examination of these regions, there- fore, we shall revert to those connexions of the rectum : in the foetus these curvatures scarcely exist, and this intestine is then nearly straight, as it is in most other animals. The rectum is connected posteriorly to the sacrum and coccyx by the meso-rectum superiorly, and by vessels and nerves inferiorly, and is separated from the former by the pyriform muscles and sciatic plexus of nerves ; anteriorly to the peritonaeum above, and below, in the male subject, to the inferior fundus of the bladder, the vesicular seminales, and the prostate gland ; in the female, to the left ovary and Fallopian tube, uterus, and vagina : along the sides of the rectum is a considerable quantity of m'BT.TN DISSECTOR. 250 cellular ti-siu-. also several vessels, particularly tortuous veins; inferiorly the levatore.s ani muscles cover and support the sides of this intestine, and its lower extremity is surrounded by the orbicular and cutaneous sphincters ; it is fixed not only by these several attach- ments, but also by the pelvic fascia, which is reflected upon its fore- part and sides ; it cannot, therefore, be displaced in hernia, but is liable to imagination from above, and to aversion or prolapsus of its mucous coat below, improperly called " prolapsus ani." The rectum is separated superiorly from the bladder in the male and from the uterus in the female by the cul de sac of the peritonaeum, which may or may not contain some of the small intestine, according to the state of the pelvic viscera. The rectum is only partially covered by the peritonaeum : in the superior third this membrane covers the intes- tine all around, forming the meso-rcctum behind it ; in the middle third it is only connected to the forepart, and somewhat to its sides ; and to its inferior third it is wholly unattached. The rectum is more cylindrical and less sacculated than the colon, and the cells present a different arrangement in consequence of the peculiar disposition of the lining membrane ; it is found in general much dilated about an inch above the anus. As the food is propelled onwards through the intestines, both large and small, it becomes mingled with a vast quantity of fluid (succus in- testinalis^, secreted by the mucous glands and follicles. In the jeju num and ileum the chyle is absorbed by their numerous villi ; the length and tortuosity of the tube, and its numerous valvulae conniventes, are admirably adapted to increase the extent of this secreting and absorb- ing surface, and at the same time to retard the progress of the food, and to penetrate and subdivide the mass, so as to search out, as it were, and extract all the nutriment or chyle it may contain. In the large intestine the contents acquire their feculent properties, the first traces of which they exhibit in the caecum. In their passage along this part of the canal the absorbents may probably continue to take up any chyle that may have escaped those in the ileum, as also the watery parts of the food, and the faeces become hardened by degrees, and moulded or figured according to the length of time they are lodged in the cells of the colon ; the great length of this tube, as well as its yielding structure, adapt it as a reservoir capable of retaining a considerable quantity, and thus obviating the inconvenience of frequent defaecation. The rectum also contributes to the same effect, being retained in a closed state by the sphincters and supported by the leva- tores ani muscles. When the evacuation of the bowels is called for by the peculiar sensations in the part, the contents are expelled partly by the muscular action of the rectum and the concurring relaxation of its sphincter, aided by the voluntary contraction of the diaphragm and abdominal muscles. The large and small intestines possess the same structure or number of coats, viz., the serous, muscular, fibrous, and mucous, but these, being differently modified in different situations, require to be exa- 254 DUBLIN DISSECTOR. mined distinctly in each division of the tube. Remove the following- portions of intestine, including each part between ligatures, having first distended them with air or fluid : a portion of duodenum, of jejunum near its commencement, of ileum near its termination, of the arch of the colon, and of the upper part of the rectum ; portions of each also should be inflated, dried, and opened, while other sections may be everted and suspended in fluid. Structure of the Duodenum It has been already stated that the serous tunic is only pai'tial ; the superior transverse portion, like the stomach, is perfectly invested by it, excepting along the superior and inferior borders, where its laminae enclose small triangular spaces ; the middle and inferior divisions are covered by peritonaeum only in front, and are very 7 loosely connected with it ; laterally and behind cellular tissue fixes this intestine hi its place ; the very termination of it has no connexion whatever to serous membrane, as the superior mesen- teric vessels intervene and lie in front of it. The muscular coat is formed of strong i*ed fibres, which take a circular direction ; there are very few longitudinal fibres to be observed along it, except on the superior transverse portion, which portion, being moveable, can be shortened by their action ; but on the middle and inferior divisions, which are fixed, such fibres would be useless. The fibrous and mucous coats are analogous to those of the jejunum and ileum, and may be examined at the same time. Structure of the Jejunum and Ileum The serous coat forms a per- fect investment, excepting in the small triangular space along their concave border, which encloses the nutrient vessels and nerves, and by the expansion of which the distension of the tube is admitted without undue extension of the investing membrane itself. The peri- tonaeum is very fine, and connected to the next coat by extremely delicate cellular tissue, in which adeps is never deposited. Although this serous coat is transparent, and so thin as to be difficult of removal, yet it is wonderfully strong, and serves to limit or restrict the distension of the tube. The muscular coat is not so strong as on the duodenum, but more evidently consists of two sets of fibres ; the longitudinal are the most superficial ; they are very pale and indistinct, except along the anterior or convex side of the intestine ; they are usually torn off with the peritonaeum in the dissection, they are so thin and transparent ; they are short ; the ends of one fasciculus being received between those of two others. The circular fibres lie beneath these ; they are more distinct, but also very pale : no fibre passes perfectly round the tube, but the extremities of each slant obliquely downwards, so as to form a series of spiral curves rather than annular bands. This coat of the intestine exerts an important influence in the digestive function ; the circular fibres, Avhich are stronger throughout than the longitudinal, especially on the duode- num, must have the effect of constricting or compressing the canal, thereby intermingling its contents and urging them onwards to the caecum, while the longitudinal fibres shorten the tube, and thus co- DUBLIN DISSECTOR. operate with the former by raising each successive convolution to receive the contents expelled from the preceding by the circular con- traction. These actions follow each other gradually, but sometimes in rapid succession along the tube, and are commonly named the vermi- cular ami peristaltic motions : the former are effected by the circular, the latter by the longitudinal fibres. The fibrous coat of the small intestine is analogous to that of the stomach. The mucous or in- ternal coat is connected to the latter by vessels and nerves, and by a fine cellular tissue, which is sufficiently loose to admit of separation by the knife, or to be permeated by air and rendered emphysematous by the blow-pipe. This membrane is continuous with and very simi- lar to that of the stomach in its general characters, but presents some peculiarities which deserve attention, one of the most important of which is the series of folds or duplicatures, named valvula? conniven- tes ; these are permanent processes or duplicatures of the membrane, and not effaced by distension, and therefore totally unlike the rugte of the stomach, which are merely accidental foldings of the lining tunic seen only in the contracted or empty, and effaced during the distended state of the organ : the valvulae conniventes should be in- spected in a portion of recent intestine opened and suspended in water, or everted and then suspended, or in a section that has been inflated, dried, and opened. They commence in the vertical portion of the duodenum, at first few and small, but soon increase in number and size, and exist in the remainder of the duodenum, in the whole of the jejunum, and upper half of the ileum ; they then again decrease in number and size, and are almost wholly absent in the last two or three feet of the ileum ; they are best seen in the jejunum ; they are semilunar folds or arches, extending round one-half or three-fourths < >f the tube perpendicular to its axis, broad in the middle, and narrow at the ends, which are often forked, and bend off obliquely, or end in vertical folds ; they are nearly parallel, and in some places so close that the edge of one will reach the base of the next, but they never overlap ; when the intestine is empty they lie flaccid, oblique, and vertical ; rugae are then also seen ; but, when distended, they become extended into shelf-like partitions, not exactly parallel, but inclined a little obliquely downwards, and alternating with one another on opposite sides, so as to render the canal a sort of spiral tube or wind- ing passage. A view of the dried preparation of these valves exhibits many of these characters very distinctly, but of course exaggerated as to strength and resistance, as they are naturally soft and flaccid, and can be folded in either direction, so that they cannot resist regurgita- tion, or act as true valves, like the pyloric or ileo-csecal ; each valve is composed of a fold of the lining membrane, enclosing nerves, blood- vessels, and absorbents ; the convex and concave edge of each appears stronger than the intermediate portion, from the existence of a fine fibrous band, which is most distinctly developed hi the duodenal folds ; they are very unequal in size, seldom exceeding a quarter of an inch, but are generally much smaller. They also vary much in different 256 DUBLIN DISSECTOR. individuals, as also in different tribes of animals. These valves are of use in increasing the extent of a highly organized surface, and in delaying the food in its passage along the canal, thus affording to the absorbents a better opportunity to imbibe all the nutritious matter or chyle which it may contain ; in proportion also as the intestine becomes distended, these valves become more tense, and project into the canal, so as to separate the food into smaller portions, and thus expose the entire mass to the action of the absorbents. The whole mucous surface of the small intestine is furnished with fol- licles and mucous glands ; it also presents numerous projecting pro- cesses, called villi, which are very distinctly seen on a portion of the membrane everted and suspended in fluid, and which give to it a fine velvet-like appearance. The follicles of Lieberkiihn are simple pouches of the membrane, very small, and scattered very numerously over the surface. They become very evident in enteritis, and are then filled with an opaque, whitish fluid ; their openings can be seen with a lens ; their ca3cal ends rest in the submucous tissue ; they generally surround the villi. The more elaborate intestinal glands present dif- ferent appearances, and are known by the very inappropriate names of glandulse Brunneri and glandulae Peyeri, also glanduhe agminate, and solitaria;, or sparsae. The glands of Brun are chiefly in the duo- denum, in the submucous tissue, they surround the intestine in the form of a lamina of white bodies, each of the size of hemp-seeds ; each con- sists of small lobules, the ducts opening into a common tube, and are very analogous to the pancreas and salivary glands, being of the same complex structure. They do not extend beyond the commencement of the duodenum. The glands of Peyer are sometimes collected into clusters (agminate), sometimes scattered separately in the lower part of the canal (solitariae) ; the former are more properly the glandulae Peyeri : in the healthy membrane they appear as small circular spots, white and slightly raised ; over these there are few, if any, villi ; the small openings of the follicles surround them ; they are chiefly along the convex part of the intestine, and are sometimes seen distinctly by holding up a portion of the extended and semi-transparent surface between the eye and the light ; no excretory duct can be seen, how- ever, leading from these glandular patches, but on rupturing one of them it is found to contain a cavity filled with mucous and small vesi- cles or cells ; it is supposed that at times an excretory duct opens from it and discharges the fluid of these cells or vesicles, or probably it has some communication with the adjacent follicles. Ulceration fre- quently destroys tliis investing membrane, and in such cases these glands appear as shallow, open ulcers. The use of these glands or bodies is unknown, as the nature of their secretion has not been ascer- tained ; indeed the latter remark is applicable to the whole extent of the intestinal mucous membrane; the secretions which are produced from the different follicles and glands cannot be procured separately, or examined distinctly, nor cannot it be determined whether they should be regarded as accessory to digestion in the same way as the gastric, hepatic, and pancreatic fluids, or as exerementitious secre- tiuiis. separating from the blood effete or noxious ingredients. We may. however, infer from the great extent of the surface, and from the abundance of secretion it affords, that any material alteration in its quantity must exercise an important influence on the general economy. The rifli are those short cylindrical, or conical processes seen on the mucous membrane in the small intestine, in some situa- tions so numerous as to give to the surface a fleecy appearance; these little processes, when examined with magnifying powers, are found to be covered not only by epithelium, but also by a fine membrane, and to contain a minute plexus of blood-vessels, through the medium of which the absorption of fluids from the canal takes place: the lacteal i!so commence in each villus by fine branches; but the most accurate and trustworthy observers of the present day deny that they open on the surface by free orifices, as was formerly supposed and very generally described ; and the same remark applies to the lymphatic \. . U which arise in the various other tissues of the body. In each villus, near its extremity, the interstices between the capillary vessels are occupied, while chylous absorption is proceeding, by very small spherical vesicles or cells containing an opalescent fluid, and, where the vesicles approach the granular texture of the substance of the villus, minute granular or oily particles are seen. When the intestine contains no more chyme, the vesicles disappear almost entirely, the lacteals empty themselves, and the villi become flaccid ; the epithe- lium, which had fallen off during the process of absorption, is then renewed. The vesicles at the ends of the villi may be regarded as cells whose lives are of short duration, selecting from the food the materials in contact with the villi, and appropriating these to their own growth, then liberating them by solution or disruption of the cell-wall in a situation where they can be absorbed by the lac-teals. This power of selection is probably a peculiar vital endowment of the cells at the extremities of the villi rather than of the lacteals, and appears analogous to the property possessed by the different cells of plants, of selecting from the common pabulum the materials requisite for the elaboration of their own peculiar products, such as colouring matter, starch, oil, &c. From our present state of knowledge of the function of absorption, which, however, is by no means perfect, it appears reasonable to conclude that the nutritive material, or the chyle, which may be regarded as imperfectly-elaborated blood, is thus absorbed by the lacteals ; and from the uniformity of its composition, notwithstanding the diversity of the food, that, those vessels, or rather the cells, at the extremities of the villi, have the power of selecting the ingredients of which it is composed ; whereas the veins only are concerned in the absorption of the fluids in the alimentary canal, these vessels being copiously distributed on the walls of the stomach and intestinal tube, and it is highly probable that the fluids are taken into them by the simple process of endosmose See Goodsir, Edinb. New Phil. Jour., July. l*i-_> ; and Carpenter's Human PhysioL, p. 393. 258 DUBLIN mSSECTOK. Structure of the large Intestine This, in some situations, as has been already observed, is but partially covered by peritonaeum : this membrane is more loosely connected to the transverse arch of the colon than it is to the small intestine, being unattached in two triangular spaces, one along the posterior concave border, between the lamina: of the meso --colon, the other along the anterior convex, between the layers of the great omentum ; these favour its distension ; it partially covers the caecum, ascending and descending colon, but is variable in this respect ; it surrounds the sigmoid flexure of the colon and the upper part of the rectum, as it does the small intestine ; from the caecum to the middle of the rectum it forms a number of processes, or cul de sacs, like omental, fatty appendices (append, epiploiciv), which vary very much in size and number ; they often contain a great quan- tity of adeps ; they diminish in size when the intestine is distended, and are elongated when it is contracted ; they have been found so long as to have caused strangulation of an intestine, or to have been engaged in a hernia : in the child they exist, but instead of adeps they contain a reddish cellular tissue. The muscular coat of the large intestine also consists of longitudinal and circular fibres ; the latter form a dee]) layer, pale and weak, and arranged as in the small intestine : the former, however, are collected into three fasciculi, all of which commence at the vermiform process, and pass along the cjecum and colon to the rectum ; of these bands one is anterior on the caecum ; the others are posterior, one internal, the other external ; they are aboiit equidistant, and a quarter of an inch broad; they are white and strong, and pos- sess considerable elasticity ; that which is anterior on the cax'iim, and on the ascending and descending colon, is somewhat inferior and ante- rior on the arch of the colon, and is enclosed between the lamina? of the great omentum ; it is the strongest band ; the posterior external band on the right and left colons and caecum, is superior and poste- rior on the arch, and is between the lamina? of the meso-colon ; the posterior internal on the lateral colons, is inferior on the arch, and is free and smooth. These two posterior bands usually unite into a broad and scattered lamina on the sigmoid flexure ; they are all shorter than the tube itself nearly by one- half, and therefore produce the peculiar cellular or sacculated form, the pouches bulging out between the bands, and constricted by circular, muscular, and cellular cord-like fibres ; the cells themselves being very thinly covered. If the intes- tine be inflated and extended, and then these longitudinal bands divided in different places, the tube will admit of extension to a con- siderable degree, and the pouches will be obliterated in the same pro- portion ; scattered, short, longitudinal fibres, also, are occasionally observed along the course of the colon. On the rectum the muscular tunic increases in thickness, and resembles that of the oesophagus ; the superficial or longitudinal lamina is continued from the bands of the colon, which have been previously expanding, but which now form a thick and perfect tunic, the vertical fasciculi of Avhich are very obvious near the anus, where they also become confounded with ix r.i.ix mssi-x.Toi:. 250 those tit' the levatur ani muscle of each side. Adipose substance i.- interposed between those and the peritonaeum. The circular fibres also increase in strength and redness as we descend, and are collected into a thick annular fasciculus a little above the anus ; this is termed the internal sphincter ani. The anal orifice is also furnished with a superficial or cutaneous sphincter, the anatomy of which, however, appertains to the perhueal region, in the examination of which, as well as of the pelvis, the rectum will again come under our notice. The internal or mucous coat of the large intestine is pale, and forms I nit few and imperfect folds. When distended and dried it presents internally several crests or semi-lunar ridges, separating the cells in the ca?cum and colon, but these are formed by all the coats, except the longitudinal bands. This membrane has no villi, but when exa- mined minutelv presents the honeycomb or irregularly pitted appear- ance of the mucous membrane of the stomach, the pits or alveoli being studded with small foramina, the orifices of numerous follicles ; it dif- fers, therefore, very obviously from the lining of the small intestine, and this distinction is abruptly marked at the ileo-ca3cal valves. In the vermiform appendix the follicles are large, close, and distinct ; in the rectum the mucous membrane is more loosely connected to the imi.-cular, particularly below, hence the frequency of its protrusion or e version, in this situation also it is surrounded by numerous veins; in this intestine the mucous membrane is thrown into several longitudi- nal plic;e. as in the oesophagus ; these are to admit of distension : it al>o presents some transverse or horizontal folds, one at its upper extremity, another about the middle, and the third lower down, this is the most regular, and extends from the anterior wall, opposite the lower fundus of the bladder; these folds are very distinct, in a dis- tended and dried intestine; they are, however, by no means regular in number or si/e. Mr. Houston, who has particularly described them (Dublin IIosp. Reports, vol. v.), considers that they are suffi- ciently large and strong to support the fa-cal mass, and thus to re- lieve the anus from its pressure ; the mucous surface of the rectum, particularly below, is furnished with many follicles, some of consider- able size, and with very distinct orifices. NVe shall conclude tin's article with a few remarks on mucous mem- brane generally, our knowledge of the minute structure and functions of which has been considerably elucidated of late years by the assis- tance of the microscope. The term " mucous membrane" is applied to those great membranous expansions which are continued from the skin to line all the internal organs and the various glandular ducts and follicles: they form, in fact, the internal integument, and, as they are always in contact more or less with extraneous matters, they are enated with a viscid secretion, termed mucus, which serves not only to defend their surface from contact, but also to lubricate the passage. The entire of the digestive and respiratory apparatus is lined by this structure, also the urinary and generative ; these two great mucous 21)0 DUBLIN D1SSKOTOU. surfaces are named, the former the gastro-pulmonary. Hie latter the genito- urinary ; to the first our present remarks chiefly apply. The gastro-pulmonary mucous membrane is continuous with the skin at the margins of the eyelids, nares, lips, and anus, lines the sinuses and recesses of the nose, the Eustachian tubes and tympana, covers the tongue, cheeks, palate, fauces, and pharynx, and at the lower part of the latter separates into two tubular prolongations ; one, anterior, descends into the larynx, trachea, and bronchial tubes, into the cajcal terminations of which it is continued ; the other, the posterior, lines the oesophagus, the stomach, and the entire alimentary canal, the pancreatic and biliary ducts and gall bladder, and the innumerable ducts and follicles that open upon this extensive surface. Although the appearance and character of this membrane vary in different situa- tions, its structure being modified according to the function of each part, yet a general similarity in tissue prevails throughout. Mucous membrane is now considered as composed of three elements ; first, the epithelium, which covers its free surface; second, the basement or papillary membrane, subjacent to the last; and third, the areolar tissue, which contains the nutrient and functional vessels and nerves, forms the principal portion of its bulk or substance, and serves to connect it to the surrounding tissues. The epithelium bears some analogy, as to structure and use, to the cuticle or epidermis on the external integument, but presents consi- derable variety in different situations ; in the mouth it consists of laminae, composed of cytoblasts, cells, and polygonal scales ; each cell and each scale has a central nucleus, within which are one or more nucleus corpuscles : the deepest lamina consists of cytoblasts only ; in the next the investing cell or vesicle is developed ; the cells by degrees become large and flattened, and in the superficial laminae are converted into thin scales. The nuclei, cells, and scales are connected together by a glutinous substance containing opaque granules ; the superficial scales exfoliate continually, and give place to the deeper layers : in the stomach and intestines these bodies are pyriform and columnar, the apices applied to the basement membrane, and the bases forming by their approximation the free surface. Each column has a central nucleus and nucleus corpuscle, which can be seen through the base of the transparent column. The columnar epithe- lium is produced in the same manner as the laminated, in cytoblasts, cells, and columns, and the latter are continually thrown off to give place to successive layers. As it is always in contact with fluids, it is soft and pliant, and, like the cuticle, it is constantly undergoing exfoli- ation and as constantly renewed ; like it, also, it is composed of small nucleated cells, which are sometimes tesselated, sometimes cylindrical ; the cells of the tesselated are polygonal, and composed of but few layers ; those of the cylindrical have the form of long cylinders or truncated cones, arranged side by side, one end free, the other resting on the basement membrane. Both forms sometimes co-exist, as in the glandular ducts ; and lien- also tin- cylinders are often ciliated, tin? motions of the cilia being towards the outlets of the canals they line. The cylinder epithelium is found in the stomach and intestinal canal, and in all the glandular ducts opening upon these: also in those of the salivary glands. The epidermoid tissues have the simplest struc - tare, and are the most easily renewed, of any solid parts in the body; there appears no limit to their reproduction; their origin appears to be in germs supplied by the basement membrane, through which the formative plasma transudes ; their duration varies in different parts ; the epidermic cells, exposed on one side to the air, soon dry, and are abraded gradually by friction or any other desquamating cause. On the internal serous surfaces, and in some few mucous, they are more permanent, but on most of the latter loss and renewal are almost in- mt. The epithelial cells, on the mucous expansions and in the glandular ducts, are considered as the really operative agents in the elaboration of the mucous secretions ; the cells are being continually cast off and replaced by fresh ones, and in this act of cell-growth the secreting process is accomplished. These cells of the tubes and folli- cles select from the blood those particles which it is their peculiar province to assimilate, and then discharge upon the surface ; but we are totally ignorant of the reason why, in one situation, cells should select one peculiar set of elements, and, in another, another, and thus produce from each organ a different secretion ; all that can be consi- dered as ascertained is, that the act of secretion is effected by the pro- cess of cell-growth, and that secretion and nutrition, or growth, appear to be analogous functions, or to be effected by analogous agen- ies, for as the cells in the extremities of the villi select from the dimentarv mass the nutritious particles which are to be absorbed, so the cells of the secreting ducts and follicles select from the blood those effete particles which it is their province to assimilate and discharge upon the surface of those canals whereby they will be removed from the system See Xasmyth's Mem. on the Teeth and Epithelium; aNo Mnc. Memb, in Todd's Cyclopa?dia of Anatomy and Phys., by Bowmen. The second lamina of mucous membrane is by some named " the basement membrane," by others " the papillary layer;" from it is pro- duced the epithelium ; its surface presents different appearances in different situations ; in the stomach it forms the cells or alveoli into which the follicles open ; in the small intestine it covers the numerous projections called villi, and in the large intestine again it presents jxdygonal cells like those in the stomach. The third element in mucous membrane is the fibrous lamina which gives it support, strength, and form, and so far is analogous to the corium in the skin, but seldom equals it in density ; it is also more loosely connected to the proper mucous lamina than the corium is to the papillary layer of the skin; it is chiefly composed of areolar tissue, in which the white and yellow fibrous elements can be detected ; these connect it to the sub -mucous tissue, from which indeed 262 DUBLIN D1SSKCTOK. it cannot be sepai'ated as a distinct lamina ; it contains the capillary blood-vessels, nerves, and absorbents. The peritonaeum and alimentary canal present many morbid ap- pearances. Peritonitis, or inflammation of the peritonaeum, is denoted by an increased and a reddish vascularity of the membrane, a number of small red vessels can be distinctly seen ; it loses its transparency, and becomes somewhat thick and pulpy ; the parietal and visceral layers are sometimes found agglutinated by coagulable lymph, which also cements the several intestinal convolutions, but sometimes the cavity is filled with serous or sero-purulent fluid, with shreds of lymph : peritonitis more frequently ends in some such effusion than in the adhesive process ; the contrary is more frequent in pleuritis ; perito- nitis also sometimes exhibits gangrenous patches, but if it have been chronic, adhesive bands and false membranes are very apparent. In ascites or dropsy of this membrane, the tissue of the latter appears sound, sometimes remarkably clear or pearly ; the intestines are usually compressed towards the spine, the fluid being accumulated in front ; in this disease some of the viscera, particularly the liver, are often found in an abnormal state. The omentmn is sometimes the seat of general induration, or of par- ticular tumours, adipose, sarcomatous, and fungoid. The omenta and the peritonaeum generally, but especially where it invests the small intestines, are not unfrequently the seat of tubercular deposit; the tubercles are often small, or miliary and innumerable. This morbid appearance is more frequently found in very young subjects. The stomach may be the seat of acute inflammation, or gastritis ; the coats will then appear more thick and vascular than usual, and blood is sometimes seen effused between them. Ulcers also are fre- quently found in the stomach, of an oval or circular form, witli thin and firm edges. Independent of disease, the stomach not unfre- quently presents considerable red patches on its mucous surface ; the coats are also sometimes nearly destroyed in some places, presenting a soft and ragged appearance ; this is caused by the gastric fluid digest- ing or dissolving the tissue after death. Both the cardiac and pyloric ends of the stomach are the frequent seat of cancer ; this principally involves the mucous and muscular tissues ; the latter becomes much thickened and intersected with grey, fibrous matter. On the former large fungoid masses are thrown out, which more or less constrict or obstruct the orifices of the organ, and impair its general functions. The intestinal tube is subject to numerous diseases, in most of which the effects of inflammation are more or less visible : inflamma- tion, or enteritis, is denoted by increased vascularity of the mucous surface and thickening of the tunics ; in some cases the peritonaaum is also engaged ; the colour of the intestine is a deep or dark red ; acute inflammation sometimes ends in gangrene and effusion, sometimes in nlceration. The whole of the intestinal surface may be the seat of ulceration ; in the small intestines the ulcers are generally small, and are often found in the situation of the mucous glands ; in the large DUBLIN mssi:< TOK. ?C>:\ intestines they are usually in larger patches, and in eases of dysentery are often very extensive. The intestinal tunics are occasionally the seat of malignant tubercle, which may obstruct the course of the contents if the tube; of all parts of the intestinal canal the rectum is most fiv ([iiently the seat of scirrhus and its consequences. The glandular viscera of the abdomen, which are subservient to digestion, are the liver, spleen, and pancreas. The lirer is the largest and heaviest secreting gland in the body ; it tills the right hypochondriiim, extends through the anterior part of the epigastric region into the left hypochondriiim, as far as the cardiac orifice of the stomach, beyond which, however, it frequently extends, even to the spleen ; it is situated below the diaphragm, and above the right kidney, the stomach, duodenum, and lesser omentum, ; is pro- tected by the seven or eight lower ribs of the right side, and is sup- ported in this situation by several folds of peritonaeum, termed inaccu- rately ligaments of the liver, viz., the falciform, round, right, left, and coronary ; these connect it to the diaphragm and to the abdominal muscles, and the lesser omentum attaches it to the stomach and duo- denum ; the inferior cava passes through it, is intimately attached to it, and also serves to retain it in its situation. Although the liver may be considered as a rixed vise us, its position can be affected by change of posture, by inspiration and expiration, and by abnormal conditions of the viscera of the abdomen, or of the thorax. Its weight, size, and figure are extremely variable, and consequently its position and extent must vary in proportion ; its weight varies from three to five pounds, and must in some measure depend on the quan- tity of blood it contains ; its transverse diameter is the longest, and is about ten or twelve inches ; the vertical diameter in the deepest part of the right lobe is about seven inches, but these dimensions are very variable ; it is in general larger in the male than in the female. The suspensory or falciform ligament is a fold of peritonaeum attached anteriorly by its convex border to the linea alba, to the rectus muscle of the right side, and to the diaphragm ; it passes obliquely backwards and to the right side, and is attached by its pos- terior or concave edge to the upper or convex surface of the liver, which it thus marks into two unequal portions, of which the right is the larger ; on these its lamina? separate, and expand over each side of this organ ; enclosed in the inferior edge of this fold is the oblite- rated umbilical vein, which substance in the adult is named the liga- menlum teres ; this, which is enumerated as the second ligament of the liver, ascends from the umbilicus obliquely backwards, and to the right side, and is inserted into a notch in the thin or anterior edge of the liver, which notch is the commencement of the umbilical or hori- zontal fissure of the liver. The falciform or suspensory ligament is improperly so called ; it cannot have the effect of supporting this organ, as it is never on the stretch. If the abdomen were much dis- tended, it might sustain the anterior surface and the inferior margin of the liver. The use or design of this fold was clearly to conduct 2tate descends no further than a transverse line eon- nei-ting the eighth rib* of opposite sides; in the foetus and infant it extends much lower, and very frequently also in the adult. The inferior surface has an aspect backwards and downwards ; it is very irregular, marked by several projections and depressions ; the former are called lobes, and are five in number, viz., first, the great or right lobe, which fills the right hypoehondrium, and is thick and nia>sy ; second, the left, thin and variable in size, separated from the former by the horizontal fissure on this surface, and by the falciform fold on the upper; this lobe occupies the epigastrium and part of the left hypochondrium, and rests on the stomach ; third, the Spigelian or mid- dle lobe; this is situated behind the lesser omentum, above and behind the transverse fissure, and between the oesophagus and the cava; it cor- responds to the lesser curvature of the stomach, and projects into the upl ier part of the sac of the omentum, towards the head of the pancreas ; the transverse fissure bounds it in front, the thick margin of the liver behind, the groove for the ductus venosus on the left side, and that for the vena cava on the right ; it is very variable in size and extent ; it has a mamillary form, the smooth and convex apex below embraced by the branches of the creliac axis of arteries ; it is con- nected to the right lobe by two roots ; one is thin, and placed verti- cally between the fissure for the vena cava and that for the ductus venosus ; the other is thick, and placed transversely, and is called lobulus caudatus, or the fourth lobe, of the liver ; the lobulus caudatus is immediately behind the transverse fissure, and in front of that for the inferior cava, and extends from the Spigelian obliquely outwards and forwards along the right lobe between the depressions marked by the colon and right kidney. Fifth, the lobulus quadratus, or anonymus, is at the anterior part of the right lobe, in front of the transverse fis- sure, and between the gall bladder and horizontal fissure ; its poste- rior border is sometimes so prominent as to have led to the name of the anterior portal eminence, as the Spigelian and caudatus lobes have been called the posterior. The principal depressions or fissures on the inferior surface of the liver are the following : first, the transverse fissure, or porta, which is situated between the lobulus quadratus and caudatus, and extends from the horizontal fissure transversely to the right ; it is very broad, and nearly two inches in length ; it is about the centre of the organ, but a little nearer to the posterior edge than to the anterior, and to the left than to the right extremity : the horizontal fissure bounds it on the left and communicates with it, and thus marks the course of the inosculation during foetal life between the umbilical and portal veins ; the lesser omentum is attached to its margins ; the sinus and the two great branches of the vena porta, the hepatic artery and duct, lympha- tic vessels and nerves, and much cellular tissue, occupy this depres- sion. Second, the horizontal fissure extends from the notch in the anterior edge of the liver backwards and upwards between the right and left lobes ; the anterior part of this fissure contains the fibrous re- 26G DUBLIN DISSECTOK. mains of the obliterated umbilical vein, the posterior part those of the obliterated duct us venosus. The anterior half is deeper than the postc rior, and is often converted into a complete tube by a transverse bridge of glandular or fibrous tissue ; the posterior half leads obliquely to the left of the Spigelian lobe, and communicates with the termination of the groove for the vena cava, and thus marks the course of the inos- culation in foetal life between the ductus venosus and the inferior cava, or rather one of the hepatic veins close to that trunk. Third, the fis- sure for the vena cava is between the lobulus Spigelii and the right lobe ; this, like the anterior part of the horizontal fissure, is frequently converted into a tube by a fibrous or glandular band. Fourth, the depression of the gall bladder is on the inferior surface of the right lobe, and to the right side of the lobulus quadratus ; the substance of the liver is sometimes deficient over this bag. Fifth and sixth, super- ficial depressions on the under surface of the right lobe ; the anterior corresponds to the colon, the posterior to the right kidney and its cap- side. These depressions are indistinctly marked in some subjects ; they are separated from each other by the extremity of the lobulus caudatus Seventh, a superficial depression on the under surface of the left lobe, corresponding to the anterior surface of the stomach. Eighth, a broad notch in the posterior edge of the liver, correspond- ing to the spine and to the right crus of the diaphragm ; the vena* cavae hepaticse leave the liver in this situation. The five principal fis- sures, namely, the horizontal and transverse, with those for the vena cava and gall bladder, have been resembled to the letter H ; the left limb being the umbilical fissure anteriorly, and that for the ductus venosus posteriorly ; the right limb, the groove for the gall bladder in front, and that for the vena cava behind, while the transverse fissure is the connecting bar. It is obvious that these five fissures are con- cerned in marking the divisions into the five lobes ; the distinctions, however, between these are merely accidental, and are only superficial, and do not exist on the upper surface, so that, strictly speaking, this great conglomerate gland is but one mass or lobe. The circumference of the liver presents anteriorly and inferiorly a thin, sharp edge, leading from the right side obliquely upwards and to the left ; on the right this edge corresponds to the border of the thorax, and looks forward* and downwards ; on it are two notches, one, very deep, leads into the horizontal fissure, and receives the fibrous remains of the umbilical vein ; the other is to the right side of this, corresponds to the base, of the gall bladder, and varies in extent and depth. The greater portion of this margin of the liver can be felt during life, when the abdominal parietes ai*e in a relaxed position. The right extremity of the circum- ference is thick, round, and smooth, and attached by the right lateral fold or ligament ; the left extremity is thin and elongated to a varia- ble extent ; the broad left lateral ligament fixes it to the diaphragm. The posterior part of the circumference is round, and thicker on the right side than on the left, adheres to the diaphragm by cellular tissue within the laminn? of the coronary fold or ligament, and presents the nritUN- MISSKCTOK. 2(57 It > ]i ;inl broad notch to correspond to the right cms of that muscle and t<> tin 1 spinal column. The groove for the vena cava terminates ;it this notch, and tin 1 large hepatic veins escape from the liver, and join that trunk. The liver is of a peculiar brown colour, interspersed with yellow ; in some subjects it is much darker than in others ; in the very young it is red and soft, and in the old it is generally pale and yellow, and often hard and brittle ; the tints and shades are of infinite variety, dark red, deep purple, brown chocolate, green, slate, pale yellow, grey, and even white ; all these depend on different degrees of conges- tion, either venous or biliary, and there is no valid reason for attributing them to two differently coloured tissues in the liver, the red and the yellow, as was considered to be the case by some. The consistence of the liver, like the colour, is very variable, even in the absence of actual disease ; it is usually dense, firm* and resisting to the feel, but sometimes it is very compact, and even hard, the edges, particularly, brittle or friable ; in such cases, it may be torn or broken, and the fractured surfaces will present a granular texture ; in other cases it is so soft as to retain the impression of the finger, or to break down under the slightest pressure ; in such instances, however, there is often a fatty degeneration of the organ. The liver has two coats, a serous and fibrous ; the serous or perito - meal tunic covers the whole surface of the liver, except in those situa- tions where the vessels, either pervious or obliterated, are situated, and between the laminae of the coronary ligament, also the depression in which the gall bladder is lodged ; this tunic is very thin, and adheres intimately to the fibrous capsule ; it gives support and con- nexion to the granules or lobules of the gland, and allows it and the adjacent parts to glide smoothly on each other. The second, or fibrous coat, is the immediate capsule to the gland ; it is thin, little more than condensed cellular membrane ; it is most distinct and strong where the serous coat is deficient ; it covers the whole sin-face of the liver, and adheres to it by innumerable shreds or processes, which pass into its substance between the granules, and forms a capsule for each lobule ; it also accompanies the three vessels of the liver which enter or leave the transverse fissure, and forms a capsule or sheath around their ramifications throughout the entire organ ; this sheath receives the name of the capsule of Glisson ; its processes or sheaths surround the vessels very loosely, as they also enclose loose cellular tissue ; externally these sheaths adhere to the lobules of the liver, as each sends off numerous processes to enclose the several granules similarly to these derived from the surface ; there is also an inflection of this tissue at the upper part of the liver, where the venae cava? hepaticae escape, but it contains no loose cellular tissue, hence it is that if the three sets of vessels, which pass from the trans- verse fissure in a radiated direction through the organ, from the centre towards the circumference, be divided by a perpendicular incision through the liver, they will be found to collapse and recede; whereas. 268 mm MX DISSK< TOK. if the venae cavse hepatic*, which run from the thin towards the thick edge of the liver, be divided by a transverse incision through this organ, they will not recede or collapse, but remain perfectly open, in conse- quence of the absence of this cellular tissue, and of their close adhe- sion to this membranous tube, to which the substance of the gland intimately adheres. This structure may be considered as the basis or foundation of the whole organ, forming not only a general covering for its surface, but for each of the granules of which it is composed, while it is also continued from the transverse fissure around the vena porta, hepatic artery, and biliary ducts, to form sheaths for these ves- sels, even to their ultimate ramifications. This capsule, though generally regarded as fibrous tissue, yet is really " a cellulo -vascular membrane in which the vessels divide with great minuteness ; it lines the portal canals, enters the interlobular fissures, and forms capsules for the lobules, and expands over the secreting biliary ducts ;" it commences in front of the spine, accompanies the hepatic vessels through the lesser omentum, and then through the organ, in the substance of which it may be divided into three portions, the vaginal, the interlo- bular, and the lobular. The vaginal portion svirrounds the hepatic artery and duct, and the vena porta in the portal canals ; the interlobular por- tion fills the interlobular fissures and spaces ; and the lobular portion supports the tissue of the lobules, and forms a capsule for each. The structure of the liver consists of numerous small granulations or lobules of a brown and yellow colour, connected together by the branches of the hepatic arteries and veins, and of the vena porta and biliary ducts, and by lymphatics and nerves, the whole of which are cemented together by Glisson's capsule, or the tunic just described. The arrangement of these several tissues has been admirably made out by Mr. Kiernan, and described by him in his excellent memoir pub- lished in the Phil. Trans, for the year 1833. To his account of this organ little can be added, and I therefore confidently refer the reader to his description of it. Although the surface of the liver is generally so smooth and compact as to appear one homogeneous structure, yet if its coats be removed, or if a portion of the gland be broken or torn, the surface presents an irregular aspect, rugged and granulated, evidently sheAving that this organ is composed of numerous minute bodies or grains closely connected together ; these, which are termed lobules, together with the ramifications of the vena porta, biliary ducts, hepatic arteiy and veins, lymphatics and nerves, all of which are cemented together by the fibro-cellulo- vascular tissue, or Glisson's capsule, constitute the mass of this very large conglomerate gland. On each of these we shall offer a few remarks. The lobules are small granules, of the size of millet seeds, but of irregular forms, rounded, and with angular prominences ; each pre- sents a base which rests upon an hepatic vein, which is therefore called sublobular vein, the remainder of this lobule is invested w r ith a capsule from Glisson's membrane ; this surface is connected to the cap- sular surfaces of the adjacent lobules ; the intervals between these 1M BL1N D1SS1-XTOK. 2i)9 lobules are called interlobular fissures, and the angular spaces formed by tlu- apposition of several of these lobules are called interlobular >paccs. The lobules* on the surface are larger and more flattened than those which are internal. Each lobule is composed of a plexus of biliary ducts, of a portal venous plexus, of an interlobular branch of an hepatic vein, and of minute arteries ; nerves and absorbents cannot be traced, but may be presumed to exist in each. The microscope exhibits the lobule as composed of numerous minute yellowish bodies, of various forms, and connected together by vessels; these minute bodies are the acini of Malpighi, and they are probably the csecal extremities or plexiform terminations of the biliary ducts : each lobule may be regarded as a very minute though a perfect gland, and the whole liver is but the aggregation and close union of these. Through the li ver four sets of vessels ramify, in addition to nume- rous lymphatics, viz., the branches of the hepatic arteries, venae por- tarum, hepatic ducts, and hepatic veins : the veme portarum are sup- po>cd to be the vessels from which the bile is secreted; the hepatic arteries nourish the substance of the liver, and join the vena portal plexus ; the hepatic ducts carry the bile from this organ, and the veiue cavo. 1 hepaticte return the blood which has circulated through the liver to the inferior vena cava, just as this vessel is passing through the diaphragm. The vena porta is a very large, a very important and peculiar ves- sel : though it arises in the abdomen as a vein, and serves the same otliee, yet in the liver it terminates like an artery, and has a secreting function ; it returns the blood from all the chylopoietic viscera to be distributed through the liver, and in the latter organ it receives the venous blood from the terminations of the hepatic artery. It is four or rive mches long, is formed by the confluence of the splenic and mesenteric veins behind the pancreas, in front of the aorta and to the left of the inferior cava ; it ascends obliquely to the right side, receiv- ing branches from the pancreas, duodenum, stomach, and gall bladder, enclosed in and conducted by the lesser omentum to the transverse li ss lire of the liver, the left extremity of which it enters, and then divides into a right and left branch ; these separate so widely as to form a short trunk or swell at right angles with the vein itself (sinus of the porta), then enter the liver, divide and subdivide into numerous branches, which radiate towards the circumference in horizontal directions, and lodged in canals, termed the portal canals, which are formed of the vaginal processes of the capsule of Glisson, and, like the superficies of the organ, by the capsular surfaces of the lobules. Each of these canals contains a portal vein and its branches, also an artery and a duct; in the large canals these vessels are sur- rounded more loosely by the capsule, but in the smaller canals the parietes are in close contact with the vein on one side, and with the artery and duct on the other. The branches of the vein are the vaginal, interlobular, and lobular. The vaginal arise in the portal canals, pass into the sheath formed by Glisson's capsule, and form in 270 DUBLIN DLS.SECTOK. it the vaginal plexus. The interlobular branches arise from the vaginal plexus, enter the interlobular spaces, and divide into branches which cover all sides of the lobules, except their bases on their perito- naeal surface ; these branches form a free communication through the entire organ. The lobular branches arise from the last, enter and form a plexus in eacli lobule, and end in a minute intralobular vein : this may be called the lobular venous plexus, and is between the inter- lobular portal veins and intralobular hepatic veins. In the meshes of this plexus are seen, by means of the microscope, the acini of Malpighi, or portions of the lobular biliary plexus. The capsu- lar veins of the liver not only join the porta, but also inosculate with the phrenic veins. In some cases of atrophy of the liver and obstructed circulation of the blood, collateral circulation has been maintained by the anastomoses between these veins, as also between the capsular branches of the hepatic artery and the phrenic and others. The hepatic artery is a branch of the caeliac axis ; it ascends in the lesser omentum to the left side of the bile duct, and in front of the vena porta enters the liver with this vein and with the hepatic ducts, pursues the same course, and divides into the corresponding branches, vaginal, interlobular, and lobular. The vaginal branches form a vaginal plexus ; the interlobular ramify in the interlobular fissures, and are chiefly distributed to the coats of the. biliary ducts ; small branches also ramify in the capsule of the liver and anastomose with branches from the phrenic, internal mammary, and suprarenal arteries. The lobular branches are very small and few ; they are the nutrient vessels of the lobule, and end in the lobular venous plexus of the vena porta. Kiernan maintains the opinion, and adduces strong evidence in its support, that the office of this artery is nutrient, and not secret- ing ; minute injections of it colour very highly the cellular tissue and the coats of the ducts and of the other vessels, as also the gall bladder, but produce very little effect on the lobules themselves. The termi- nating branches of this artery have no communication with the hepatic veins, but all join the lobular venous plexus of the porta, which is the secreting agent ; the intralobular veins, which are the radicles of the hepatic veins, receive the blood, not from the arterial capillaries, but from the lobular venous plexus. The hepatic ducts may be traced from the transverse fissure along with the last- mentioned vessels, and present the same order of branches, vaginal, interlobular, and lobular; the first form a vaginal biliary plexus, from which proceed the inter- lobular, which ramify on the capsular surface of the lobules, and freely communicate with each other ; the lobular ducts proceed from these, some also from the vaginal plexus ; these enter the lobule, and form within it the lobular biliary plexus, in which the ducts end either in csecal extremities, or in anastomosing arches. The coats of the ducts are very vascular ; they possess many mucous follicles : these are distributed irregularly in the large ducts, but are arranged in two longitudinal and parallel rows in the smaller. Hepatic reins convey the blood from all parts of the liver to the Drill. IN DISSl-X'TOK. L'71 vena cava ; they arc- also divisible into the three orders: intralobular, sublobular, and hepatic trunks. The intralobular pass through the central axis of the lobule and through the centre of its base, and end in the sublobular veins. The tublobuUtr veins are lodged in canals formed by th<- bases of the lobules, and are in close contact with the latter without the intervention of any of (ilisson's capsule; they are thin and transparent, and, if laid open, the bases of the lobules will be distinctly seen, separated by the interlobular lissures, and perforated in the centre by the intralobular vein. The hepatic veins are formed by the union of the sublobular veins ; they are lodged in canals lined by the capsule of the liver, but not surrounded by cellular tissue or vaginal plexus ; they all proceed from before and from below upwards and backwards, and end in two or three large trunks, which open into the cava close to the diaphragm : in this course they cross the brandies of the porta which radiate from the centre towards the mar- gins of the liver. When cut at right angles they remain open, and retain their cylindrical form, as they are closely connected to the lining of the hepatic canals in which they are lodged : no other vessel is enclosed with them, whereas every branch of the vena porta is accompanied by a small artery and bile duct, and the three are enveloped in the capsule of Glisson. The right and left hepatic ducts are nearly of cental size, and, on clearing the transverse fissure, unite at an obtuse 'angle, and form the hepatic duct, which descends for about one inch and a half along the right side of the lesser omentum, is then joined at an acute angle by the cystic duct, from the gall blad- der : the union of these forms the ductus coininumts clwledociius ; or rather the hepatic duct may be said to give off the cystic, which, pa>.>ing backwards and to the right side, dilates so as to form the gall bladder, and the ductus choledochus may then be regarded as the con- tinued hepatic duct. This vessel, about three or three-and-a-half inches long, descends obliquely backwards, at first in the lesser omen- tum. in front of the vena porta, and to the right of the hepatic artery ; then it passes behind the pylorus, the upper part of the duodenum and the pancreas, and is imbedded in the substance of the latter ; about the middle of the internal or concave side of the middle division of the duodenum it perforates the coats of this intestine in a very oblique direction, and opens on a small papilla internally, opposite the lower angle of the duodenum : as the ductus choledochus is about to perfo- rate the duodenum, it is in general joined on the left side by the duct from the pancreas. The lymphatic vessels of the liver are very numerous, and art- arranged' into a superficial and deep set ; the former present a net- work appearance beneath the peritonaeum, often very distinct ; the latter are larger, escape by the transverse fissure, enter the lesser omentum. and end some in the adjacent lymphatic glands, and others in the thoracic duct. The nerves are small : a fe\v from the pneumogastric, and probably some fine filaments from the right phrenic ; but the principal supply 272 DUBLIN DISSECTOR. is from the solar plexus; these form a plexus around the hepatic artery, and some also around the vena porta, and accompany these vessels as far as the eye can trace them. The gall bladder is of very variable size, is situated in the right hypochondrium in a depression on the inferior surface of the right lobe of the liver, between the right extremity of the transverse fissure and its anterior margin, and to the right side of the lobulus quadratus ; this membranous sac is of a pyriform figure ; the large extremity or fundus being directed forwards and downwards, and to the right ; in some it projects below the liver against the abdominal muscles, opposite the outer border of the right rectus muscle, and the cartilages of the ninth and tenth ribs ; it is generally contiguous to the pylorus and to the colon ; the smaller extremity or neck is directed upwards, backwards, and to the left ; is a little convoluted, and ends in the cystic duct, which is about an inch and a half long : this duct bends down- wards and inwards, and joins the hepatic duct at an acute angle, the union with which forms, as was before mentioned, the ductus choledo- chus. The gall bladder is closely united to the liver by the perito- naeum, which passes over it ; also by cellular membrane and small blood-vessels ; it is composed of three coats : a serous, which is only partial, a perfect cellule-fibrous coat, and a lining mucous membrane ; the latter has a peculiar honey-comb-like appearance, and in the duct is disposed in a spiral valvular lamina ; there is no appearance of a muscular coat. This viscus serves as a reservoir for the bile, when this fluid is not required in the intestinal canal ; and that its office is but secondary may be inferred from its absence in many animals ; it is wanting in all invertebrata ; the biliary ducts in these open on the surface of the digestive organ. In fishes it first appears, but is absent in many genera, and rudimentary in others, as a mere dilatation of the bile duct. It exists in all the reptilia ; in the ophidia it lies at a distance from the liver, and has therefore a very long cystic duct ; in the chelonia it is buried in the substance of the organ, and receives the bile by hepato-cystic ducts. In many birds it is absent, and in many it is present ; in the latter the bile is brought to it from the liver by an hepato- cystic duct ; the hepatic opens into the duodenum near the cystic ; there is no choledechus duct. In mammalia it is very uncer- tain ; it is absent in most herbivora, as horse, elephant, stag, but is present in many, as ox, sheep, and goat ; in one giraffe it was want- ing, in another it was double. The hepatic, cystic, and choledochus ducts are all composed of similar tissues, viz , a fine lining mucous membrane, thin and follicular, continuous Avith that of the duodenum and the gall bladder ; a middle, fibrous, and areolar texture, which most probably possesses some contractile property, and are external, cellular, and partial peritonaeal covering ; they are all thin and very dilatable ; the latter property is exemplified throughout the whole series when the flow of bile is arrested by any obstruction at the duodenal extremitv of the ductus choledochus. l>li;l. IN DISSECTOR. 273 I he lik- is sei'ivted in the liver, flows down the hepatic duct, and, if not required in the duodenum, or if obstructed in the ductus cholc- * The superior surface of the liver. 1. The right lobe. 2. The left lobe. 3. The anterior thin edge. 4. The posterior thick edge. 5. The suspensory or fal- ciform ligament. 6. The ligamentum teres. 7. The right lateral ligament. 8. The left lateral ligament. 9. The portion of the thick border of the li ver which is uncovered by the peritoneum, and surrounded by the coronary ligament. 10. The inferior vena cava cut across. 11. The posterior extremity of the Spi- gelian lobe. 12. The fundus of the gall bladder, projecting beyond the anterior edge of the liver. The inferior surface of the liver. 1. The right lobe. 2. The left lobe. 3. The Spigelian or middle lobe. 4. The lobulus caudatus. 5. The lobulus quadratus. 6. The pons hepatis, not always present. 7. The notch in the anterior edge of the liver, forming the commencement of 8. 8. The horizontal fissure. 9. The obliterated umbilical vein. 10. The obliterated ductus venosus. 11. The trans- verse fissure. 12. 12. The vena cava inferior. 13. The gall bladder. 14. A su- perficial depression, corresponding to the colon. 15. A similar one correspond- ing to the right kidney and supra renal capsule. T 274 DUBLIN DISSECTOR. dochus, passes into the cystic duct to the gall bladder, where it remains a longer or shorter period, during which some of its watery part is ab - sorbed ; at the end of some time, when required to assist in digestion, it is forced out of the gall bladder, and then flows again along the same cystic duct to the ductus choledochus, and so to the duodenum. The bile is not secreted in the gall bladder, nor can it possibly enter or leave this viscus by any other channel than through the cystic duct, as there are no hepato-cystic vessels, as in reptiles and in some birds. The office or use of the liver is to secrete the bile ; it is most pro- bable also that it exerts an important influence in sanguification, or in the purification of the blood. The secretion takes place in the lobules from the great venous plexus of the portal vein, and as the blood of the hepatic artery has become venous previous to its passage into the lobular venous plexus, this secretion must be wholly from venous blood ; the elements which are thus separated from the venous blood of the chylopoietic viscera, and which constitute the bile, are useful in digestion, and are supposed to act chemically on the chyme in the duodenum, and to produce the separation of the chyle ; the bile also combines with the residual or ftecal matter, to which it imparts its peculiar colouring matter, and it also stimulates the mucous surface of the intestinal tube to pour forth its secretions, and the mus- cular coat to contract upon its contents. That the liver also exerts some additional function in depurating the blood may be inferred from the great size of this organ compared with that of its excretory appa- ratus ; the considerable magnitude of it in foetal life, when the biliary secretion is scanty and not required in digestion ; the large venous system that is expanded through it; the proportion it bears in- versely to the lungs, but directly to the necessity for removing from the blood a larger quantity of hydrogen and carbon ; in the herbivor- ous animals, in the quadrumana, and in man, it is not so large as in the carnivora ; in birds it is larger, as there is great need of highly oxygenated blood ; in fish and in reptiles, with cold blood and imper- fect respiration, it is still larger ; it is also very large in the inver- tebrata. No viscus in the abdomen presents such frequent and varied abnor- mal appearances as the liver. The pathology of many of these has been much elucidated by the anatomical and physiological researches of Kiernan. Inflammation, acute or chronic, of its peritonaeal coat, or membran- ous hepatitis, is marked by the usual characters of serous inflamma- tion. The capillaries are injected with blood and coagulable lymph is effused, agglutinating the adjacent parts; adhesions more frequently occur on its convex than concave surface. This condition may exist independently of inflammation of the organ itself, though some con- gestion in the latter is commonly present. The mucous lining of its excretory vessels may also be in a state of acute or chronic inflammation, caused by extension of irritation from the mucous membrane of the gall bladder, duodenum, or alimentary m m.ix DISSI-XTOR. 275 oanal. This induces thickening, contraction, and partial obliteration of the ducts, and may thus become the source of many chronic diseases of the liver, and abnormal changes in its tissue. Hepatitis, or acute inflammation of its parenchyma, is seldom seen in the dead body ; it is denoted by a deep red or purple colour, a firm and heavy feel, and some increase in size ; the investing mem- branes are easily detached, and the subjacent surface is very granular and vascular. Hepatitis often ends in suppuration ; the pus may be collected in several small cysts through the liver, or diffused among its lobules, or it may be collected into one large abscess, the contents of which may be discharged in various directions, and recovery ensue. Adhesive inflammation attaches its walls to the surrounding parts, or to some adjacent viscus, and ulceration gives exit to its contents with- out any effusion into the abdomen. By this process an hepatic abscess may point, and be opened by the surgeon through the abdominal parietes, or between the ribs, or it may burst into the pleura, or by the continuation of the same adhesive process it may become attached to the lung, and the matter may escape into the bronchial tubes, and be coughed up, or it may open into the stomach, or duodenum, or colon, and be discharged through the alimentary canal; it has also been known to have opened into the pericardium and into the vena cava. The liver, containing an extensive venous expansion, is frequently the seat of abscess, in consequence of injuries of the head, or of the bones, or of wounds, or operations in any part of the body in which phlebitis has occurred. From a number of observations and ingenious experi- ments, Cruveilhier has concluded that in all these cases there has been a capillary phlebitis in the part injured, and that the globules of pus carried thence to the lungs and liver have produced irritation and sup- puration in these organs. In all such cases of hepatic suppuration he has found similar purulent deposits in the lungs ; in all visceral abscesses from this cause we find around the inflamed veins indura- tion, effusion of blood, lymph, and pus ; the latter also is found in the minute veins, and, when in the liver, diffused among the lobules, pro- ducing a sort of granite-like appearance. I'l-nnns congestion in the liver is very frequently seen in the dead body, and is to be considered rather as an effect depending on the abnormal state of some other organ or function than as a disease of this organ itself ; congestion may be partial or general, and it may be in the hepatic venous system, or in the portal. In hepatic venous con- gestion, the hepatic veins, their intralobular branches, and the central portions of their lobular plexuses, are all congested ; the centres of the lobules are red, while their non-congested margins are white, or yellow, or green, according to the quantity of bile in the ducts. This is the usual state of the liver after death, and arises from an impediment to the flow of flood through the hepatic veins, while the portal circula- tion still continues. This form of congestion will be very strongly marked in some diseases of the heart, and in acute disease of the lungs or pleura? ; in such cases the liver will be found large and full, from T2 276 DUBLIN DISSECTOR. the quantity of blood it contains ; sometimes also it will be in a state of biliary congestion : this combination gives rise to various appear- ances, known under the name of " nutmeg or dram-drinker's liver." Portal venous congestion is very rare, and has been only seen in children. In this the congested portions are never so red as in the last form ; the centres of the lobules are pale and non-congested, while the interlobular fissures and spaces are strongly so, and of a much deeper colour than natural ; from the liver this congestion may extend to the vessels of the alimentary canal, and give rise to gastric and intestinal haemorrhages, also to haemorrhoids and ascites. In general congestion the whole substance of the liver presents a diffused red colour, the central portions of the lobules being of a deeper hue than the margins. Hypertrophy differs from congestion, and implies an actual increase in size and growth ; it may be the result of chronic inflammation of the mucous tissue, or of any cause that has obstructed the circulation. In some instances it is found congested also, but in others pale and anemic. Atrophy is denoted by diminished size of the whole or of a part ; the lobules are indistinct, and often appear compressed by the cellular tissue, which is increased ; the hepatic venous congestion is sometimes combined ; the surface is often marked by irregular lines or grooves. This condition of the liver has been thought to have been induced in some cases by the injudicious pressure of tight dress ; it may also be the result of antecedent chronic inflammation. Cirrhosis is atrophy of the parenchyma and hypertrophy of the cellular tissue or basis of the liver ; some lobules are wholly, others par- tially atrophied, and the remainder are in a state of biliary congestion ; the organ is often diminished to one-half its size, and changed into a shapeless mass, the surface withered, with furrows, ridges, and wrin- kles of varying tints of green and yellow. On dividing it the struc- ture feels dense, and is irregularly granulated ; ascites, jaundice, and thoracic disease, are often concomitants to this abnormal condition of the liver. The liver is sometimes indurated to an extraordinary degree with or without hypertrophy or atrophy ; it is not unfrequently preterna- turally softened, so as to break into a grumous pulp under very slight pressure ; it is also sometimes so loaded with a fatty or oily matter as to resemble the liver of the cetacea ; this state is termed fatty degene- ration. The liver is the deposit of various species of tubercle ; the common scrofulous, the small diffused, the large circumscribed, the soft brown, the scirrhous, the fungoid, the melanotic, the hydatid ; this latter is in the form of a cyst, which sometimes contains several smaller hydatids, one enclosing the other ; these hydatids are classed by some under the head of the acephalyst entozoa ; small intestinal worms also have been occasionally found in the biliary ducts ; these probably have ascended from the duodenum through the choledochus duct. IH'KI.IX DISSECTOR. Zt i The morbid appearances found in the gall bladder are : great disten- sion from obstructed ductus choledochus, or total obliteration of its cavity from obstruction in the cystic duct ; it often contains biliary calculi ; if one only, it is usually large and ovoid ; if many, as is coni- monly the case, they present every variety of form and size, with smooth sides and defined angles, the probable effects of constant fric- tion one against the other. The spleen is a soft, spongy, vascular mass, very variable in size and consistence ; its texture, even in a healthy state, is often so weak and soft, or so brittle, as to break down under the slightest pressure. It has no excretory duct ; but as its vein directly joins the porta, and so reaches the liver, it may with great probability be regarded as accessory to this organ in its function of sanguification or of depura- tion of the blood. It is situated in the left hypochondrium, between the stomach and the ribs, beneath the diaphragm, and above the kidney and the colon : it is in contact with and connected to the diaphragm by the peritonaeum, also to the stomach and pancreas by vessels and by the peritonaeum. It is somewhat of an oval form, or a longitudinal sec- tion of an ellipse ; convex towards the ribs, and concave towards the stomach. On the latter surface there are several holes, and about the centre of it a depression or fissure, with a row of foramina for the entrance and exit of the blood-vessels and nerves ; this depression is named hilus of the spleen. The gastro-splenic omentuni, which con- tains the vasa brevia, is attached in this situation ; all this surface is not equally concave ; the part anterior to the vessels is most so, and is more or less closely related to the cul de sac of the stomach. The posterior portion is often convex, and is related to the left kidney, suprarenal capsule, left end of the pancreas, and left cms of the diaphragm, which separates it from the side of the spine. The smooth convex surface is in contact with the diaphragm, and by it is sepa- rated from the three or four last ribs. The upper extremity, large and round, is in contact with the diaphragm, and sometimes with the edge of the left lobe of the liver ; the inferior end smaller, thin, and ilatk'iK'd, is in contact with the left part of the arch of the colon, rests on the mesocolon, and is moveablc ; the posterior margin is thick and round, and often deeply notched ; the anterior edge is more thin and sharp, and is also often deeply notched ; these notches are uncertain, and appear rudimental divisions into lobes. The spleen, though a fixed viscus, partakes of some motion or change of place according to the state of the surrounding parts, parti- cularly of the diaphragm and stomach ; in deep inspiration it descends a little, and when the stomach is distended the lower extremity is tinned somewhat forwards ; it is then also more closely applied to the surface of its cul de sac, and has more of a horizontal than a vertical position. The size of the spleen is very variable, even more so than that of the liver ; in some it appears shrunk, with its capsules wrin- kled and loose, in others they are full and tense. It would appear, therefore, to be subject to distension and collapse, and many suppose 278 DUBLIN DISSECTOR that these conditions alternate in the inverse ratio with the correspond- ing states of the stomach. The colour of the spleen is very variable, from a deep, dark red to a pale grey, purple, livid, marbled, often like a leech ; long exposure to the air brightens the red colour. The spleen possesses two coats, serous and fibrous ; the serous or pe- ritonseal invests all portions of it except the hilus, which corresponds to the space between the laminae of the gastro-splenic omentum ; it gives a smooth covering, and attaches it to the surrounding organs. The fibrous or proper coat is thin and transparent, but very elastic ; the serous is closely united to it externally, and from its internal surface numerous shreds pass into the spleen all over its surface, while at the hilus it is not perforated, but inflected around the vessels, the ramifica- tions of which it accompanies, and joins the processes derived from the surface, so as to constitute a cellular or areolar basis or frame- work to lodge and to support the vascular tissue of the organ ; this areolar tissue may be well seen by macerating and washing away the blood from a divided spleen. Injection and inflation also demonstrate the same structure ; this tissue is divided into compartments, and hence injection will sometimes fill some of these only, leaving the others flaccid. These fibrous cells are filled with a substance like grumous blood ; they also contain a number of small red corpuscles, the nature of which is not understood. In addition to these cells and their con- tents this organ is essentially composed of blood-vessels. The splenic artery is the largest branch of the coeh'ac axis ; it is remarkably tor- tuous, and enters the spleen by five or six branches ; each of these pursues the same tortuous course within its substance, and divides into many ramifications ; those from one branch do not join those from another, so that the spleen may be regarded as a number of spleens, as in the case of conglomerate glands ; the spleen occasionally receives additional arteries from the phrenic, lumbar, and suprarenal. The splenic vein is much larger than the artery, and is the principal root of the vena porta ; its branches form the greater portion or bulk of the organ, so that it resembles a venous erectile tissue ; the cells are believed to communicate with the veins, or rather perhaps the former are but modifications of the latter, and that they are in fact composed of the lining membrane of the veins, supported by the fibrous sheaths and bands of the areolar texture. The nerves of the spleen are very distinct ; they are derived from the solar plexus, and twine around the artery and its divisions ; some small filaments also from the pneumo-gastric, in the gastro-splenic omentum, pass towards it in the course of the vasa brevia. The lymphatic vessels are superficial and deep ; some pass from the stomach towards the hilus, and enter the lymphatic glands. The exact use or function of this viscus is not yet ascertained ; sometimes two or more small bodies, of the same colour and structure as the spleen, are found in its vicinity between the laminte of the omentum. The spleen is not often found diseased ; the greatest possible variety DUBLIN DISSECTOK. 279 as t.i si/.o and consistence is observed without any morbid change ; in ome rases it is so soft as to break under the slightest pressure: its coats are subject to thickening and induration, cartilaginous and even bony tubercles or patches are very common occurrences in its fibrous capsule. The pancreas lies behind the stomach, and may be exposed by dividing the great omentuin between this organ and the colon. This conglomerate gland, in colour and texture, is very similar to the sali- vary glands ; it is flat, thin, and elongated, about seven inches long, and an inch and a half broad ; it extends from the lower part of the left hypochondriac and epigastric regions obliquely downwards and forwards into the umbilical region, where it is surrounded by the duo- denum ; it is covered by the stomach and the ascending layer of the mesocolon ; it lies anterior to the left crus of the diaphragm, the vena porta, the aorta, the vena cava, superior mesenteric artery, left kidney and suprarenal capsule, and the two first lumbar vertebrae ; the great end or head is encircled by the duodenum, the concave border of which it overlaps, and to which it adheres very closely, somewhat as the sublingual salivary gland does to the mucous membrane of the mouth : the middle portion is called the body. The splenic or left extremity (its tail} is small compared with the right, which is broad and flat, and is named the head ; the anterior surface looks a little upwards, the inferior edge being raised forwards and separated from the duodenum by the superior mesenteric artery and vein, which pass behind it through a deep groove or tubular passage in the gland ; a groove may also be remarked on its posterior and upper part, which contains the splenic artery and vein. The pancreatic duct is im- bedded in its substance, and may be seen by scraping off some of the surface of the gland about its centre. This duct is remarkably white and thin ; it commences in the small extremity of the gland, and extends to the large end, receiving in its course numerous branches on each side : it very generally joins the ductus choledochus in a small, ampulla-like dilatation, just before the duodenal opening ; sometimes there is a second duct, which opens into the duodenum distinctly ; attached to the head of the pancreas there is sometimes a glandular mass of the same structure as the pancreas, and opening by a small vessel into the pancreatic duct ; this is named the lesser pancreas. The pancreatic fluid is supposed to be of use in diluting the bile, and rendering it and the contents of the duodenum more miscible with each other. The structure of the pancreas is similar to that of the salivary glands, and is thence called by some the abdominal salivary gland. The pancreas is not often found in a morbid state ; induration of its structure and calculi in its duct may be occasionally noticed, and in -nun' cases distending the latter into a serous cyst: it is sometimes found adherent to the back part of the stomach, and in chronic nice- ration of the coats of the latter this gland has been found supplying 280 DUBLIN DISSECTOK. the deficiency, and thus preventing effusion from its cavity : its proxi- mity to the aorta and to the pylorus renders it at times extremely difficult to distinguish between the diseases of each. SECTION III. OF THE VESSELS AND NERVES OF THE ABDOMEN. THE abdominal aorta gives off three large branches to supply the organs of digestion, viz., the coeliac axis, the superior mesenteric and inferior mesenteric arteries. The coeliac axis may be seen by tearing through the lesser omentum above the lesser curvature of the stomach ; it arises from the forepart of the aorta, at the upper edge of the pan- creas, is about half an inch long, and divides into three branches, the gastric, hepatic, and splenic ; the gastric artery and its branches run between the laminae of the lesser omentum, along the concave edge of the stomach, and supply both surfaces of this organ. The hepatic ar- tery accompanies the vena porta and the biliary duct to the transverse fissure of the liver, first sending off a small branch to the pylorus (py- lorica superior), next a large branch (gastro duoderialis), which descends behind the pylorus, and subdivides into two branches, the pancreatico-duodenalis and gastro-epiploica dextra ; the former sup- plies the pancreas and duodenum ; the latter runs along the convex edge of the stomach, between the layers of the great omentum ; the hepatic arteiy then divides into the right and left hepatic arteries, which supply the right and left lobes of the liver ; the right hepatic is the larger, and gives off a small branch, arteria cystica, to the gall bladder. The splenic artery is the longest and largest branch of the cceliac axis ; it passes along the upper and posterior part of the pan- creas, to which it gives many branches ; near the spleen it sends off the gastro-epiploica sinistra, which runs along the convex edge of the stomach, between the layers of the great omentum ; the splenic artery then divides into five or six branches, which enter the foramina in the concave surface of the spleen : from these splenic branches five or six small arteries, the vasa brevia, pass -to the left or great end of the sto- mach. The superior mesenteric artery arises about an inch or less below the cosliac axis, behind the pancreas ; it descends in front of the duo- denum, enters the mesentery, and bends obliquely towards the right iliac fossa ; from its left or convex side it sends off sixteen or eighteen branches, which supply the jejunum and the ileum, and from its con- cave or right side arise three branches, the ileo-colica, colica dextra, and media ; these arteries supply the corresponding portions of the colon, and inosculate with each other. The inferior mesenteric artery arises a little above the division of the aorta into the iliac vessels ; it l>ll;l.IN 1USSKCTOK. 281 .1,-Mviuls t> tlu-. kit sitks and divides into three branches : the colica .-ini^tra. which supplies the left lumbar colon, and inosculates with the colica media ; the sigmoid artery, which supplies the sigmoid flexure of the colon ; and the superior hgemorrhoidal, which is distributed to the rectmn. These arteries are accompanied by corresponding veins, which all unite to form the vena porta. The inferior mesenteric vein accompanies the artery of that name to the aorta, and there joins the superior mesenteric vein, which is a very considerable vessel ; this common trunk then ascends behind the pancreas, and is joined by a very large vein from the spleen ; the confluence of the splenic and mesenteric veins forms the commencement of the vena porta ; this vessel ascends obliquely to the right side, surrounded by nerves and cellular membrane, and enclosed in the lesser omentum ; near the transverse fissure it becomes dilated (the sinus of the porta), and di- vides into the right and left branches ; the former is the larger, the latter the longer of the two ; each branches out through the li ver, sur- rounded by the capsule of Glisson, and runs hi a transverse direction : by the assistance of minute injections their terminating branches can be traced to the lobular venous plexus, in which they end. The nerves which supply the digestive organs are the eighth pair, and the splanchnic branches, from the sympathetic : the eighth pair descend along the oesophagus, and are distributed almost wholly to the stomach ; some few branches pass along the lesser omentum to the liver, some also join the solar plexus. The splanchnic nerves are two in number, a right and left ; they are each formed by filaments from the dorsal ganglions of the sympathetic nerve in the thorax ; they enter the abdomen either along with the aorta, or perforate the crura of the diaphragm on either side of that vessel; in the abdomen each nerve soon ends in a large ganglion, the semilunar ganglion, from which numerous branches pass across the aorta, around the coeliac axis, and, communicating with each other, form the nervous plexus, named solar or cmliac plextis, from which a fasciculus of nerves ex- tends along each of the branches of the coeh'ac artery to supply the viscera in the epigastric region ; thus a few accompany the gastric artery, and communicate with the eighth pair on the stomach ; several surround the hepatic artery, and by it are conducted to the liver ; in like manner others also pass to the spleen. From the lower part of the solar plexus several large branches descend, and become attached to the superior and inferior mesenteric arteries, form plexuses around these vessels, and receive additional branches from the lumbar or ab- dominal ganglions of the sympathetic nerves ; these nerves then twine around the mesenteric arteries and their branches, and are thus con- ducted to the intestines, in the internal tunic of which they terminate. See Anatomy of the Nervous System. The student may now re- move the abdominal viscera. Tie the lower extremity of the oesopha- gus and the upper end of the rectum, each with two ligatures, and divide these tubes between them ; dissect out the vena cava from the liver, cut across the hepatic vessels, the coeliac axis, the superior and 282 DUBLIN DISSECTOR. inferior mesenteric arteries ; and then separate the liver, spleen, pan- creas, and alimentary canal, from their connexions to the parietes of the abdomen ; next clean the surface of the abdominal aorta and vena cava, the right and left kidneys, and the renal capsules. The abdo- minal aorta may be now seen to pass into the abdomen, between the crura of the diaphragm, opposite the last dorsal vertebra ; it then descends obliquely to the left side of the median line, and divides on the body of the fourth lumbar vertebra into the right and left iliac arteries. The abdominal aorta sends off the following branches : first, the two phrenic arteries ; second, the cosliac axis ; third, the superior mesenteric artery ; fourth, the two renal arteries ; fifth, the spermatic arteries ; sixth, the inferior mesenteric artery ; also four or five pair of lumbar arteries from its posterior part; and lastly, from the angle of its division the middle sacral artery descends. The right and left iliac arteries descend obliquely outwards and backwards ; that of the right side is the longer of the two ; opposite each ilio- sacral articulation each common iliac artery divides into the internal and external iliac. The external proceeds along the inner side of the psoas magnus, and, passing beneath Poupart's ligament, becomes the femoral artery ; just above this ligament it sends off two branches, the epigastric and the circumflex ilii. The internal iliac artery descends into the pelvis, and gives off several branches, which shall be noticed afterwards in the dissection of that cavity. The veins in the abdomen correspond to the arteries ; each external iliac vein ascends along the inner side of the artery of the same name, and near the sacrum is joined by the internal iliac vein, which ascends from the pelvis ; the union of these on each side form the common iliac veins ; each of these ascends behind its accompanying artery ; and opposite the right side of the fourth or fifth lumbar vertebra these veins unite, and form the inferior or ascending vena cava ; the left common iliac vein is longer than the right, and passes behind the right iliac artery. The vena cava ascends along the right side of the aorta, and receives the sper- matic, renal, and lumbar veins ; it lies, inferiorly, on the right psoas muscle, and on the right crus of the diaphragm ; superiorly, it inclines forwards and to the right side, and enters the fissure in the liver ; here it receives the venae cavse hepaticae ; it then passes through the open- ing in the tendon of the diaphragm, and arrives at the right auricle of the heart. On each side of the abdominal aorta the sympathetic nerves may be seen ; they pass from the thorax into the abdomen, beneath the true ligamentum arcuatum, and then descend between the crus of the diaphragm and the psoas magnus on each side ; in this course they form three or four oval ganglions. At the last lumbar vertebra these nerves pass outwards and backwards, and then descend into the pelvis. The commencement of the vena azygos may be observed on the right side of the aorta ; it is formed by the first or second lumbar veins, which communicate with the renal and inferior lumbar veins, and sometimes with the inferior vena cava. The vena azygos enters the ])( BI.IN DISSJ-X'TOR. 283 thorax between tin- aorta and the right crus of the diaphragm, and then asiviids along the posterior mediastinum. The thoracic duct also may be seen to commence in the abdomen by the union of several ab- sorbent vessels on the body of the third lumbar vertebra ; this vessel, being larger here than it is above, has received the name of recepta- fiilniit cfu/li ; this, however, does not always exist. The thoracic duct is covered at first by the aorta ; it then ascends obliquely to its right side, and enters the thorax between it and the vena azygos. Let the student next examine the urinary organs ; these consist, first, of the two kidneys, which secrete the urine ; second, of the two excretory ducts, -the ureters, which convey this fluid to, third, the urinary bladder, which retains it for a longer or shorter time ; and fourth, the urethra, w r hich discharges it externally, and which, in the male, is common to both the urinary and genital organs. SECTION IV. DISSECTION OF THE KIDNEY AND UKETERS. THE kidneys present the well-known form of the kidney-bean ; the size is not so variable as that of some other glandular organs, yet one is often found larger than the other ; in general both are larger hi the infant, and in the female than in the male. The average dimensions are from four to four and a half inches in length, about two in breadth, and one in thickness. Sometimes there is only one kidney, which is then very large, of an irregular shape, and partly extended arross the spine like the pancreas ; sometimes the two kidneys are con- nected by a transverse glandular band, and resemble a horse-shoe, the concavity upwards, in the same manner as the lateral lobes of the thyi'oid body are connected by the transverse or middle lobe, the concavity of wliich is also upwards. The colour is a dark, brown red ; the texture is very firm to the touch. Each kidney is situated in the posterior part of each lumbar region, behind the peritonamm, between the last rib and the crest of the ilium, and corresponds to the two last dorsal and two first lumbar verte- bra ; the right kidney is often a little lower than the left, particularly in the female, also if the liver be larger than usual ; they are imbedded in a quantity of adipose substance, and lie on the diaphragm, psoas, and quadratus lumborum muscles, the fascia of the tranversalis abdo- niinis intervening ; the right kidney is also sometimes in contact with the iliaeus interims muscle : the ascending colon and duodenum lie anterior to the right, and the descending colon to the left kidney ; the right is in contact with the liver above and with the caecum below ; and the left with the spleen above and the sigmoid flexure of the colon below. The anterior surface of each is convex and directed 284 DUBLIN DISSECTOR. Fig. 48.' outwards ; the posterior is flat, and directed inwards ; in the young subject the surfaces are very uneven, the kidneys at that age being lobulated. The external border of each is smooth and convex, and directed outwards and backwards ; the concave edge is of much less extent, looks forwards and inwards, and presents the notch, or hilus, or pelvis, which is more open or distinct anteriorly ; it contains the arteries, veins, and excretory duct ; the veins are usually, but by no means constantly, anterior ; the arteries, five or six in number, are behind these ; and the ureter is posterior and inferior to both ; a plexus of nerves and lymphatics accompany these vessels. The superior end of each kidney is rounder, larger, and nearer to the spine than the inferior, which is directed outwards ; it is also surmounted by the su- prarenal body. The kidney is described by some as having three tunics : serous, cellulo-adipose, and fibrous ; the latter, however, alone deserves this name ; the peritonaeum is but very partially connected to its anterior surface only, and to a varia- ble extent; the cellular and adipose substance, in which each organ is im- bedded, differs in quantity and qua- lity ; in the young the cellular tissue predominates, in the old the adipose ; the proper coat is a strong, smooth, fibrous membrane, which adheres closely to its substance, preserves its form, and is continued into its inte- rior, along the vessels, as far as the calyces of the kidney ; it also sends in small shreds or processes from almost every point of the surface ; these are friable, and break in tearing this mem- brane from the gland, which is easily effected, and in doing which it can be divided into two distinct laminae. Re - move one kidney from the subject, and divide it by a perpendicular in- cision from the convex to the concave edge ; the gland will then be found to consist of two distinct substances, the external or vascular, the inter- nal or membranous, or the tubular cones. The external, vascular, or cortical substance, forms the superficial lamina of the gland, is about two lines thick, and sends long prolongations inwards, between the tubular fasciculi ; it is of a deep red colour, like muscle, particularly along its internal margin ; when the three vessels of the kidney are * A section of the kidney, shewing its internal structure. 1. The suprarenal capsule, attached to the upper extremity of the kidney. 2. 2. The fibrous tunic of the kidney. 3. The vascular or cortical substance. 4. 4. The tubular portion. 5. 5. The papilke. 6. 6. The calyces. 7. 7. 7. The infundibula. 8. The pelvis of the kidney. 9. The ureter. DUBLIN DISSECTOR. 285 injected minutely -with differently coloured fluids, and sections made of the cortex, the latter will be found to be very vascular and very tubular, as well as granular or glandular in appearance ; the minute arterial and venous ramifications are entangled with convoluted urini- fcrous tubes (tubes of Ferrein), and by the aid of the microscope an immense number of small granules can be detected in connexion with these tubes ; these are the corpora or acini of Malpighi. The intimate structure of these Malpighian corpuscles has been ably investigated by Mr. Bowman (the account of his anatomical researches, as well as his physiological views respecting the probable function of these bodies, have been published in his excellent paper in the Phil. Trans., 1842) ; they are very minute, about the T 5 of an inch in diameter ; their number corresponds with that of the convoluted urinous tubes, within the extremity of one of which each of them is lodged : a Mal- pighian corpuscle is a tuft of capillary arteries, arranged in loops closely pressed together and enclosed in a slight dilatation of the uri- nary tube, which thus forms a capsule for it : a small artery, called vas inferens, pierces this capsule, and then divides into the branches, which are coiled up to form this little vascular ball, from the interior of which a minute vein proceeds (vas efferens), which is smaller than the artery, piei'ces the capsule close to it, and along with other similar veins enters the venous plexus, which surrounds the convoluted urinous tubes, and from which the blood is ultimately conveyed from the kid- ney by branches converging and uniting to form the renal or emul- gent vein. Thus there are in this gland two perfectly distinct systems of capillary vessels, and through both the blood passes in its course from the arteries into the veins : the first is an arterial capillary sys- tem, forming the Malpighian tufts enclosed within the dilated extre- mities of the uriniferous tubes ; the second is the venous plexus, which surrounds these convoluted tubes ; this latter plexus rcvxmibles the portal plexus in the liver, which is entirely venous, though it receives the blood from the hepatic artery, and is in that gland the true secret- ing agent : so this renal plexus, which receives the efferent vessels of the Malpighian tufts, is essentially venous. Mr. Bowman advances the ingenious and plausible theory that the Malpighian or arterial capil- lary tufts are the media by which water, and the more simple and soluble elements of the urine, are discharged from the blood ; whereas by the venous capillary plexus, which is analogous to the portal, the proximate constituents of urine, such as urea, lithic acid, &c., are separated from the system. Internal to the cortex is the tubular substance, which consists of fine vessels of a pale colour and dense structure ; arranged in py- ramids or striated conical fasciculi, about fifteen in number; the base of each is directed towards the circumference, the apex towards the hilus of the kidney ; the base adheres to the cortex, which, by its prolongations inwards, envelopes each cone completely, except its apex or papilla : all these envelopes are continuous ; the section of this gland, therefore, shews that it is lobulated ; each lobe is a perfect kid- 286 DUBLIN DISSECTOR. ney ; these lobes are partially separate in the foetus, but in many animals are still more so during their whole life ; in some they are so separate as to resemble a bunch of grapes ; in partial disease of this organ, also, this lobular structure is occasionally well marked. These tubes are like fine hairs ; they are numerous towards the cortex, but diminish in number as they approach the apex or papilla ; although their diameter must be extremely minute, yet pressure on the cortical substance causes the urine to exude distinctly from these cut tubes, not only when they have been divided in the section, but also through numerous puncta on each papilla; in tracing these ducts from the apex of each cone towards the base, or towards the cortex, their num- ber appears to increase by dichotomous division, and on arriving at the cortex a total change takes place in their appearance ; at first view they would seem to end, or to commence abruptly at that line, but close inspection proves that they are continued into the cortical tissue, but altered in appearance and in direction ; they become ramose and tortuous, are inseparably entangled with the venous plexus and the arterial capillaries, and end either in caeca or in loops or arches ; hence the tubular structure of the kidney may be considered as consisting of two portions, one is convoluted and distributed through the cortex, the other is arranged in converging striae to form the cones or pyra- mids, and is only enveloped by the cortex; this latter portion, or the tubular cones, are probably only excretory in their office ; while the former, or the convoluted tubes, being surrounded by the venous plexus, and enclosing the Malpighian tufts, must be the seat of the essential part of the secreting process : at the junction of the cortex and the pyramids a line of a deep red or purple hue is observable, marking, in an undulating course, the whole extent of the inner sur- face of the former ; in this line some peculiar mode of division and inosculation occurs between the renal arteries of each lobule, which up to ^his point have been distinct. The papilla or the mamillary processes form the apices of the cones, and as two of the latter often converge into one point, the num- ber of papillae is less by four or six than that of the cones ; each papilla is perforated by several small holes, through which the urine may be observed to flow when the tubular cones are compressed ; some of them are blunt-pointed or cupped, with the orifices in their depressions ; each papilla is covered by a fine mucous membrane, which is continued through the foramina into the tubuli ; this mem- brane is also expanded round its base, and forms a little cup or calyx, which receives the fluid as it distils from the puncta ; the papilla? pos- sess no peculiar tissue, and are, therefore, essentially similar to the tubular cones which end in it, or which form it ; in its mucous epithe- lium, probably, there is some difference. The calyces are the membranous or fibro-mucous cups which, by one extremity, embrace the bases of the papillae, and by the other join the adjacent calyces to commence the ureter ; their number, six or eight, is less than that of the papillae, as two of the latter often DUBLIN DISSECTOR. 287 unite into one, and are received into the same calyx ; they are dense and white, composed externally of the fibrous coat of the kidney, and internally of a fine mucous membrane, which is continued from the mvtcr along the pelvis of the kidney, lines all the calyces, and is re- flected in the form of a very fine membrane over each papilla, and most probably is continued into the tubuli uriniferi. The calyces in each extremity, as also those in the centre, unite into three small tubes, which, being of a funnel shape, are called infundibula ; these have but a short course, and soon terminate in the pelvis of the kid- ney, which is a membranous reservoir formed by the union of the calyces or the infundibula, of a flattened oval figure, placed behind the blood-vessels of the kidney, and terminating in the ureter, which it resembles in structure ; adipose substance generally surrounds it, as well as the infundibula and the calyces. Each kidney receives a very large artery (the renal or emulgent), which arises at right angles from the aorta : this divides into six or eight branches, which enter the notch in the gland, subdivide into numerous fine vessels, which proceed between the tubular portions to the cortex ; at the line of junction of these two, or along the convexity of each conical fasci- culus, these branches form a net- work of inosculating arches, from which proceed numerous capillaries ; some are for the nutrient func- tions, and others, according to Mr. Bowman's views, become the vasa inferentia for the Malpighian coi-puscles, hi which they divide and sub- divide, and finally converge to the vasa efferentia, or the efferent veins, which are smaller than the arteries : these veins then proceed to join the capillary venous plexus surrounding the cortical or the con- voluted uriniferous ducts. The arterial plexus in the corpora Mal- pighiana separate the aqueous and saline, and the venous plexus the proximate principles of the urine, into the convoluted ducts ; thence the fluid passes into the conical tubuli uriniferi, which convey it to the papillae, through the small pores of which it gradually flows into the calyces, and from these into the pelvis, and so into the ureter. From the renal venous plexus the blood is conveyed by veins which converge to form the renal or emulgent veins ; these veins, one on each side, open distinctly into the cava ; the left renal receives the spermatic veins, is longer than the right, and passes in front of the aorta, below the vena porta and behind the duodenum and the superior mesenteric The nerves are derived from the solar plexus, lesser splanchnic, and lumbar ganglions of the sympathetic. The lymphatics join the lum- bar glands. The function of the kidneys is to separate or excrete certain effete n/oti/A'd substances, especially urea, which cannot be retained in the body with safety to health, or even with long continuance of life; these substances have accumulated in the blood during its circula- tion, and, if not removed, soon give rise to general disturbance of the s\ ISSK< TOK. cava or the renal vein : the nerves are numerous, they are from the semiltinar ganglion and from the solar and renal plexus. In the in- terior of each we often find the appearance of a small triangular cavity filled with a brownish fluid ; the walls of this cavity are very rough, no excretory duct can be found leading from it : the presence of this cavity is by no means uniform, some deny its existence altoge- ther, and attribute the appearance of it either to decomposition or laceration, or to the opening of the vein. The exact use of these bodies is not ascertained. The renal capsules in the adult are thin, and of a brownish yellow colour, and very variable as to size ; the right has been observed to be larger and of a different form from the left : in the foetus they are very large and vascular, nearly equal to the kidney in size, and contain a quantity of reddish fluid. These bodies, though usually described as appendages to the kidneys, yet have no such intimate connexion with them as to lead to the idea that there is any functional association between these organs ; there is more reason to suppose that they are influential in sanguification during uterine life, and, like the liver, thymus, and thyroid bodies, all large at that age, are concerned in the economy of the foetus, and pro- bably assist in performing some offices connected with embryonic existence, nutrition, and growth. The kidneys occasionally present the following morbid appear- ances : inflammation or nephritis is denoted by increased redness, of a dark tint, vascularity, and induration, and sometimes attended with pu- rulent infiltration ; when the ureter is engaged it is also found thicker and redder than natural, with purulent matter on its inner surface. Inflammation also sometimes ends in a well-defined abscess in the kid- ney. The inflammation may have involved all the tissue in the gland as well as its coverings ; or it may be confined to the former without the latter being engaged, or it may be seated in the mucous lining of the calyces and pelvis of the ureter. In both acute and chronic inflam- mation of this organ red dots and ecchymosed spots are often observ- able both on the surface and in the cortical tissue ; similar dots are also often seen in the early stage of Bright's disease, or granular degeneration with albuminous urine ; these probably indicate inflam- mation of the Malpighian corpuscles, which, as they become enlarged and indurated, impair the other tissues, and the function of the gland is proportionably deranged. These glands are frequently the seat of scro- fulous abscess, in which the pus is white and curdy. Calculi are very com- mon in the kidney, sometimes they are small, and found in the tubular portion, but generally they are large, and fill up more or less of the pelvis of the ureter, not unfrequently extending by a stalk a short distance along that tube, and presenting a branched appearance at the opposite extremity corresponding to the infundibula. When the calculus is large and obstructs the flow of urine, the membranous portions of the gland become dilated, and should the stone be impacted lower down in the ureter, this tube will also become greatly dilated above the seat of the obstruction ; in such cases the interior of the kidney will be- u 290 DUBLIN DISSECTOR. come more and more compressed and absorbed, and in time nothing- will remain but the thickened capsule with a thin layer of vascular and glandular matter, containing several cells which communicate freely ; sometimes the whole of the sac will be found in a state of sup- puration. Hydatids are common formations in the kidney, they are found on its surface and beneath its capsule ; they are generally scat- tered, each in its distinct cell. The kidneys present great variety as to form, size, colour, and consistence, without any known correspond- ing difference in function. In diabetes they have been found large, vascular, soft, and easily torn ; in purpura with hematuria the lining membrane has appeared turgid, and petechiaj have been distinctly seen beneath it. The kidneys may be the seat of cancer, fungus hse- matodes, and melanosis. The bladder and urethra are the next divisions of the urinary organs to be examined ; as these, however, are pelvic viscera, we shall post- pone their consideration for the present, and the student should next examine the deep muscles of the abdomen, .viz., the diaphragm, the quadratus lumborum, psoas parvus, psoas magnus, and iliacus inter- nus of each side. SECTION V. DISSECTION OP THE DEEP MUSCLES OF THE ABDOMEN. THE diaphragm is one of the most important muscles in the human body, second only to the heart ; it is the principal agent in respiration, and belongs to the class of mixed muscles ; volition can influence it to a great degree, but cannot wholly control its actions, which continue with surprising regularity through the whole of life, during sleeping and waking time, almost without our cognizance ; its structure also partakes of the mixed character ; in colour, in the possession of tendon and of fixed osseous attachments, it is like the voluntary, while in thin tissue and expanded form, and in being single, it resembles the involuntary or the hollow muscles ; and though it is attached to or encircled by bones, yet it is not designed to act on these as levers, like the voluntary muscles, which latter always lie around or external to the bones they are to move, whereas its contractions are only in- tended to influence the regions and the viscera between which it is interposed. This muscle should be examined both on its abdominal and on its thoracic aspect ; in the former it is exposed when the abdo- men has been opened, its viscera removed, and the peritonaeum with the connecting lamina of fine and closely adhering cellular tissue dis- sected from it ; in the latter the thorax must be opened before the abdomen, and the heart and lungs, with the pericardium and pleurre, detached : the inferior surface is generally selected for dissection and PIS.SKCTOR. 291 ,1, srription. The diaphragm may be said to divide the body into an upper and a lower half, and to constitute an active and moving septum Ix'twrcn the thorax and the abdomen, forming an irregularly convex tioor to the former, and a vaulted or concave ceiling to the latter ; it Fig. 49.* crosses the median line, and, being but partially allied to the voluntary muscles, it wants the lateral symmetry of that system, although it is partially divided before and behind into right and left ; the former, however, is more extended and more deeply arched than the latter. It is usually divided by the anatomist into two portions, but which are not to be considered as distinct muscles : one is superior, large, and broad transversely (the true or costal diaphragm) ; the other is inferior and posterior, small, thick, and narrow (the appendix, crura, or pillars, or vertebral diaphragm) ; these two portions, though sepa- rate at their osseous attachments, are yet blended together in the com- mon central tendon, and present a fan-shaped expansion, bent at their junction, the broad superior expanded portion being nearly horizontal or with an aspect downwards and forwards, while the posterior infe * A view of the diaphragm during expiration. 1. The superior extremity of the sternum. 2. The first rib. ?,. The dorsal region of the spine. 4. The supe- rior surface of the central tendon of the diaphragm. 5. The right lateral portion of the diaphragm. 6. The left lateral portion. 7. The xiphoid cartilage. 8. The right cms or pillar of the diaphragm. 9. The left cms. 10. The body of the third lumbar vertebra. 11. The posterior fibres of the diaphragm. 12. The aorta passing between and behind the pillars of the diaphragm. U 2 292 DUBLIN DISSECTOR. rior portion is vertical, and joined to the former at nearly a right angle, and has its surfaces directed forwards and backwards. The superior or true diaphragm is broad, thin, and circular, or rather transversely elliptical, being narrower from the sternum to the spine than from side to side, fleshy in the circumference, tendinous in the Fig. 50.* * The inferior or abdominal surface of the diaphragm. 1. The sternum. 2. 2. The costal cartilages. 3. The body of the third lumbar vertebra. 4. 4. The crests of the ilium. 5. 6. 7. The superior or true diaphragm : the figure 5 is placed on the anterior portion of the central tendon, the figure 6 upon the right, and the figure 7 upon the left division. 8. The posterior fibres of the diaphragm arising from the false or external ligamentum arcuatum. 9. The true ligamen- tum arcuatum. 10. The right eras of the diaphragm. 11. The left eras. 12. The aortic opening in the diaphragm through which the aorta is seen passing. 13. The inferior extremity of the ossophagus passing through the oesophageal open- ing. 14. The opening for the vena cava. 15. The quadratus lumborum muscle. 16. The psoas parvus 17. The psoas magnus. 18. The iliacus internus : the in- ferior extremities of the last three muscles have been removed. 19. The poste- rior portion of the transversalis abdominis muscle giving origin to its posterior tendon, the anterior lamina of which (20) is seen passing in front of the quadra- tus lumborum muscle. DUBLIN DISSECTOR. 293 centre, itritn-s anteriorly from the back part of the xiphoid cartilage I iv two weak fasciculi, separated by a line of cellular tissue (the me- dian line, analogous to that which separates the crura posteriorly) ; these ill >rcs arc sometimes absent, and then a considerable deficiency exists in this situation ; in some they are very strong, and appear to draw the cartilage inwards and backwards; external to these, and between them and the lateral fibres, there is in general a well-marked triangular space on either side, in which the pleurae and peritonaeum are connected by cellular tissue, and through which the terminating branches of the internal mammary vessels pass to the abdominal parietes ; thoracic and cervical abscesses sometimes take this course, and point in the epigastric or umbilical region ; violent exertion also might even force some of the abdominal viscera through this weak part, so as to cause diaphragmatic hernia ; the lateral and middle fibres arise from the internal surface of the cartilages of the last true and of all the false ribs, and from their contiguous bony portions, these fasciculi, at their origin, indigitate with those of the transverse muscles of the abdomen ; the anterior are the shortest ; the middle, those between the eighth and eleventh ribs, are the longest ; the fasciculi from the two last ribs are often attached to a considerable portion of these bones, and are also often connected to the transverse muscles by a common apo- neurosis ; the posterior fibres are thin and weak, but longer than the anterior ; they arise between the last rib and the spine, from the upper part of the strong but thin tendinous expansion, which is the anterior layer of the transversalis tendon, and which covers the quadratus lum- borum muscle, and adheres to the last rib ; the upper part of this fascia is strong, and so tense, when the last rib is everted, as to resemble a ligamentous cord between it and the spine, and has received the name of external or false Kpamatfwm arcuatum, to distinguish it from the internal or true lit/amentum arcuatum, which lies internal to the former, and is a true tendinous arch, attached by one cornu to the transverse process of the first lumbar vertebra, and by the other to the body of the second and to the tendon of the adjacent pillar or crus of the dia- phragm ; this true ligament, concave downwards, arches across the sympathetic nerve and the upper end of the psoas magnus muscle ; the anterior branch of the last dorsal nerve passes beneath, or rather through the external ligament ; the posterior fibres of the true dia- phragm arise from these two ligamentous structures ; those from the true or internal ligament are stronger, and are in connexion with the outer border of each crus ; those from the external or false ligament are pale, weak, and indistinct, and very often deficient in muscular structure ; from this extensive circular origin the fibres converge towards the central tendon, like radii from the circumference to the centre of a circle; the anterior, short and slender, pass backwards and upwards to its border, the lateral or middle fibres inwards and upwards, and then a little downwards to its sides, forming curved lines or arches concave downwards, convex upwards; those on the right side are longer and more arched than those on the left, the con- 29-i DUBLIN DISSEOTOK. vexity of the former being on a level with the fourth rib, that of the latter with the fifth or sixth; these long, curved, lateral fibres are immediately beneath the lungs ; the posterior fibres pass upwards and forwards to reach the back part of the tendon. The central or cordiform tendon of the diaphragm (phrenic centre) occupies considerable extent, and being surrounded or insulated by fleshy fibres, it constitutes the diaphragm a digastric muscle both from before backwards, and from side to side. It is a thin, tendinous expansion, of great transverse breadth. Its figure has been compared, not unaptly, to the trefoil leaf, the posterior notch receiving the inser- tion of the crura as the stalk, one leaf or lobe extending towards the left side, beneath the left pleura ; this is the smallest division, is long and narrow : a second leading forward towards the xiphoid cartilage ; this is usually the broadest and strongest portion, lies on a plane infe- rior to the others, and is immediately beneath the heart and pericar- dium : the third, extending to the right side, is larger than the left, and very often equal to the anterior or middle division. The relative size of these lobes is variable, and the tendon altogether is smaller in pro- portion in the young than in the old ; its fibres radiate from behind forwards and outwards, but are interlaced by transverse and oblique bands, in addition to which strong accessory fasciculi are attached to it, and cross it in different directions ; some of these are unattached in their centre, these are chiefly seen on the right leaf. This platted texture is more distinct on the abdominal than on the thoracic sur- face ; it obviously imparts mechanical strength to this thin expansion. Behind the left division is the fleshy opening for the passage of the O3sophagus ; and behind the right, or rather in the angle between it and the middle lobe, is the tendinous one for the vena cava ; of these we shall speak presently. The tendon is the highest part of the dia- phragm, less arched and more fixed than the fleshy portion. Behind and below this tendon are the two crura or appendices, or vertebral portions of the diaphragm, nearly parallel to the spine. The right cms, longer, thicker, and on a plane anterior to the left, arises by tendinous fibres from the anterior and right lateral surface of the bodies of the first four lumbar vertebrae and their intervertebral liga- ments ; the left, smaller and on a posterior plane, arises from the left side of the two first vertebrae ; both are confounded with the anterior vertebral ligament, and both also receive their external fibres from the true ligamentum arcuatum ; they ascend obliquely forwards, diverg- ing a little, but are soon connected to each other by a semilunar ten- dinous band, concave downwards, which is arched over the aorta and thoracic duct ; this tense cord is opposite the last dorsal vertebra ; it might be named the middle ligamentum arcuatum ; from its convex edge fleshy fibres proceed to each crus. A little above this the crura not only approximate so closely as to appear as one, but each sends a fasciculus to join the other ; these are named the decrissating fasciculi : that from the right crus is the larger, that from the left is smaller, and sometimes it crosses the former on a plane anterior to it. The exact DL'lil.IX DI.SSI-X'TOK. 295 arrangement of these fibres is very variable, but they always separate the aortic from tin- u-sophageal opening. The crura continue their course upwards and forwards;, and, increasing in breadth, are inserted into the notch and into tin- posterior border of the central tendon. The right cms is immediately covered by the vena cava, the right suprarenal body, the semilunar ganglion, and the liver ; the left by the aorta, left suprarenal body, and semilunar ganglion, spleen, and stomach. The duodenum, pancreas, and vena cava are also anterior to both. The superior or true diaphragm is related inferiorly to the liver, stomach, spleen, and kidneys ; it is lined throughout by the peritonaeum, except nt the coronary ligament of the liver, where the latter organ is in con- tact with it ; also posteriorly the kidneys intervene. It adheres to the muscular fibres by means of a fine but compact lamina of cellular tissue ; much of the physical strength of the muscle depends on this connexion ; the fasciculi are often separated by considerable intervals, particularly near the ribs, and in the interstices the pleura and peri- toneum are in juxtaposition. The thoracic surface is covered by three serous membranes, the pleura at each side, and the pericardium in the centre ; this surface is flat in the middle, and convex on each side, particularly the right ; the fibrous lamina of the pericardium adheres most intimately to the circumference of the anterior division of the tendon, particularly in front, where fibres of the latter ascend upon the former, and are lost in its tissue ; these serve to fix the tendon, and prevent its depression or descent. The serous lamina is connected to the tendon more loosely within this fibrous attachment ; the peri- cardium is also attached to the fleshy fibres between the anterior and left lobes; the adhesion between this membrane and the tendon is much less intimate in the child, and in some animals scarcely exists ; in the mediastinal spaces, before and behind the pericardium, the pleurae have no connexion to the diaphragm ; these membranes cover the superior lateral surfaces very perfectly, except small portions of their circumference, where the fleshy fibres come into contact with the triangulares sterni, intercostal, psoas magnus, and quadratus lumbo- rum muscles ; the diaphragmatic portions of the pleuras and the con- necting cellular tissue are not so dense as the corresponding struc- tures on the lower surface, and do not impart such physical strength. Indeed the diaphragm is very variable as to texture or apparent strength ; in some the fasciculi are very pale, weak, and separate ; and in all cases, when both surfaces have been cleanly dissected, it pos- - but little firmness or cohesion, loses its form, and becomes soft and flaccid ; much, therefore, of its normal strength and tension depend upon its investments, particularly upon that of the lower sur- face Three large openings exist in the diaphragm : one for the aorta, of ;i semilunar form, and in the median line; one for the inferior cava, nearly s([iiare and to the right side; and one for the oesophagus, ellip- tical and to the left side. The aortic opening leads from the posterior mediastinum into the 296 DUBLIN D1SSECTOK. abdomen, opposite the last dorsal vertebra, and nearly in the mesial line ; it is rather a tendinous passage behind and between the crura, which fold inwards and meet in an aponeurotic expansion behind the artery, while, anterior to the vessel, is their connecting tendinous semi- lunar cord. The thoracic duct and vena azygos ascend through it along the right side of the aorta ; the splanchnic nerves also, especially the left, sometimes escape by it ; but these nerves, particularly the right, very often perforate the crus on each side, and thus divide one or both into secondary crura or pillars. This is almost always the case with the lesser splanchnic nerves ; the parietes of this foramen are fixed, strong, and tense, and the fleshy fibres, which arise from its margin, cannot possibly contract its calibre, or constrict the parts passing through, as some have supposed. The opening for the oesophagus and eighth pair of nerves, is supe- rior, anterior, and to the left of the aortic, opposite the ninth or tenth dorsal vertebra, but not perfectly fixed, of an oval form, about an inch and a half long, and directed obh'quely backwards and downwards ; it is immediately behind the central tendon, which sometimes bounds its anterior extremity ; the decussating fasciculi form its parietes, separate it from the aortic passage, and would appear capable of con- tracting it, and thereby closing the cardiac orifice of the stomach so as to prevent regurgitation of its contents when subjected to the pressure of the abdominal parietes. The opening for the vena cava is at the back part of the right ten- dinous leaf, in the angle between it and the anterior, in front of the insertion of the right crus and opposite the ninth dorsal vertebra, on a higher plane than either the aortic or oasophageal, to the right side of the median line, and nearly fixed in its position ; its figure is an irregular square, the anterior or right sides being longer than the others ; it appears larger than the vein, along which small filaments of the phrenic nerves also enter the abdomen ; its margins are perfectly tendinous, with fasciculi crossing at right angles, and are attached to and prolonged upon the vessel, so as to form a sort of tendinous and valvular passage ; the anterior and lateral descending to the liver, the posterior ascending to the pericardium and to the right auricle ; the contraction of the diaphragm, so far from constricting this opening, must have an opposite effect, as the fleshy fibres, which are attached to three of its sides, will have a tendency to divaricate them, and so to enlarge the opening. The dimensions of the oesophageal and vena caval openings are so accurately adapted to the parts passing through them as to leave no opportunity for the escape of any of the viscera of the abdomen into the thorax ; therefore, the diaphragm can be scarcely said to be deficient in these situations. The same remark applies to the five tendinous arches posteriorly, namely, the aortic hi the middle, and the two ligamenta arcuata on each side ; the first is fully occupied by the vessels passing through it, and its edges are connected by a dense tissue to the artery and to its great caeliac branch ; the space beneath the true ligamentum arcuatum is filled by the sympathetic DUBLIN IHSSEC'TOK. 297 and psoas inagnus muscle, and a fascia is continued from its margins along the surface of the latter ; there is no space or deficiency beneath the external ligamentum arcuatum ; in addition to the three openings just described, there are numerous small ones for the passage <>t' IUTVCS and vessels, but too variable as to situation, and too insigni- ficant in size, to merit particular attention. The diaphragm is well supplied with blood ; it is the seat of many inosculations between vessels from different and distant sources, whereby a due supply is secured, one proportioned to its importance in the economy, and adequate to maintain its irritability and power of long continued action; the phrenic arteries behind and other small branches from the aorta, from the renal and lumbars of both sides, the internal mammary in front, and the intercostals all around, are freely distributed to its tissue ; the veins open into the cava either directly or into other veins proceeding to this trunk. The nerves are numerous, and, in conformity with the mixed cha- racter of the muscle, are derived from the spinal and from the sympa- thetic systems. The spinal nerves are symmetrical ; of these the two phrenic are the most important ; they arise from the cervical segment of the spinal cord, or from the third and fourth cervical nerves, descend along the anterior scaleni into the thorax, and, passing on either side of the pericardium, arrive at the diaphragm ; at the lower part of the neck they communicate with the sympathetic, pneumogastric and descendens colli nerves ; near the diaphragm they divide into four or five branches, most of which pierce the muscle anterior to the tendon, but one or two accompany the vena cava on the right side ; they ramify on the abdominal surface, the larger pass backwards, and many of them communicate with branches from the solar plexus ; the intercostal branches of the five or six inferior dorsal nerves are distri- buted to its costal fasciculi, and branches from the superior lumbar to the crura ; delicate filaments from the pneumogastric nerves are also sent to it from the cardiac portion of the stomach, and each phrenic artery is accompanied by a fasciculus from the solar plexus ; these latter follow the divisions of these vessels into the most minute rami- fications. Pathological research, and experiments on living animals, have established the fact that the phrenic nerves are the most influ- ential agents in the respiratory actions of this muscle ; the inoscula- tions between these and the eighth, ninth, and sympathetic, establish important sympathies between this muscle and the tongue, larynx, lungs, heart, and stomach : the dorsal and lumbar branches pro- bably associate it with the muscles of the trunk, as we find it co- operating with these in all the violent exertions of the body, while the branches of the solar plexus, which accompany its chief nutrient arteries, may be regarded as essential to its organization, as well as establishing a sympathetic connexion with the abdominal viscera. No other muscle in the body, then, receives nervous endowments from so many and from such varied sources, a fact fully in accordance not only 298 DUBLIN DISSECTOR. \vith its use and power, but also with the extensive sympathy it main- tains with all the organic and animal functions of the system. Use. It is the principal muscle in effecting inspiration, as it en- larges the chest in the perpendicular direction, and almost exclusively on each side ; the crura act as long muscles do towards their origin, and slightly depress and draw backwards the central tendon ; they also fix it. The superior diaphragm acts more like the hollow muscles ; the border of the tendon, and the margins of the ribs, which are held steadily everted by the intercostal muscles, serve as its fixed points, and when the fibres contract they descend, and then, instead of being curved and convex upwards, become nearly straight, so as to present a plane surface to the abdomen, looking downwards and forwards ; as the fleshy fibres are longest at the sides, it is here the greatest descent hi the muscle occurs, consequently the thorax is most enlarged beneath each lung, and in proportion as this change takes place the air rushes into these organs by the larynx and trachea, to fill the enlarging tho- rax, and ordinary inspiration is said to have taken place. There is but little enlargement or alteration in the centre beneath the heart and great vessels ; any such change in that situation would be not only useless, but injurious. When the diaphragm relaxes, its own elasti- city, together with that of the pleurae and pericardium, which are con- nected to its superior surface, aided by the pressure of the abdominal parietes against the viscera they enclose, cause it to re-ascend, so as again to present a concave surface to the abdomen, and to diminish the capacity of the thorax. The lungs are compressed in the same proportion ; the air is expelled, and then expiration is said to have occurred. Although the diaphragm is commonly said to descend in inspiration, yet this assertion must be taken with some limitation ; the tendinous centre admits of very little change in this direction, and the fleshy fibres can only become straight ; accordingly the liver, sto- mach, and spleen are not much depressed, but these, as well as the other abdominal viscera, are pushed forwards rather than downwards ; this may be ascertained by inspecting the abdomen during life in any person lying in the horizontal position on the back, prominence of the abdomen being synchronous with inspiration ; but the most careful examination can hardly discover any descent of the margin of the liver in ordinary breathing ; if, however, a very full inspiration be made, the viscera are then perceptibly depressed, and even a fulness in the perineum is perceived ; the attachment of the diaphragm to the ribs would, no doubt, tend to draw these bones inwards, and thereby contract the thorax transversely, which would be contrary to the ge- neral intention, but synchronous with its action is that of the inter- costal and levatores costarum muscles, which, by fixing these bones, not only prevent such a result, but also actually enlarge the thorax by slightly elevating and everting their lower margins. In ordinary inspiration these are the only agents employed, the diaphragm and intercostal muscles ; but in forced or in laborious breathing several l> IT. LIN DISSECTOK. 299 other muscles <>f the trunk and of the upper extremities assist, such as thr sterno-mastoid, scaleni, subclavian, serratus magnus, trapezius, pectorals, latissimi dorsi, and serrati postici. Expiration does not require the same muscular exertion; its ordinary degree is chiefly effected by elasticity and by the gentle resilient contraction of the abdominal parietes ; the ribs and their cartilages, the lungs, the dia- phragm, and the textures connected to its upper surface, all possess this property, and tend to produce this condition without any distinct muscular action, thus presenting an example of an elastic or mechani - cal force saving an expenditure of a vital power ; in violent expira- tion the abdominal muscles and levatores ani act with increased force, the triangulares stenii depress the cartilages of the ribs, the quadrati lumborum muscles assist in depressing these bones, the serrati postici inferiores may cooperate, so may the latissimi dorsi, by acting towards the lumbar vertebra 1 , and the arms themselves may be made to contribute by compressing the walls of the thorax ; and should the last rib be lixed, it is also possible that the series of intercostals may become muscles for expiration : besides these ordinary respiratory movements, the diaphragm is also essentially concerned in other phe- nomena more or less connected with this function, such as snuffing, sighing, yawning, hiccough, &c. Neither is its influence on the abdo- minal viscera to be overlooked, its alternate depression and elevation must contribute to their functions; the secretions of the liver and pan- creas, the contents of the gall bladder, stomach, and intestines, and the general circulation of the blood throughout this cavity, cannot fail to be beneficially affected by the constant motion and pressure of this muscle ; in vomiting also it is concerned, a full inspiration pre- ceding the expulsive efforts of the abdominal muscles and of the sto- mach itself ; this is instantly followed by its relaxation, which opens the cardiac orifice : in the forcible expulsion of the urine and fasces it is n-tained in a state of strong contraction, and presents a resisting surface against which the abdominal muscles press the viscera, and thus expel their contents. In these abdominal actions it principally cooperates with the tranversales, the only muscles with which it indi- gitates : a striking resemblance in structure exists between these and the diaphragm ; the two transverse with their weak and loosely attaclu-d fasciculi and their central tendon, being a sort of digas"- tric muscle expanded around the peritonaeum, and forming with the diaphragm one continuous muscular sac, enveloping and compressing the dig .-stive apparatus. We may regard this muscular envelope as completed below by the levatores ani, which, though described as two, yet might be considered a single muscle like the diaphragm, with its median aperture, opposed to it in situation, and in function, as far as respiration is concerned, but allied to it and cooperating with it and Avith the transversi as general compressors and supporters of the abdo- minal viscera. The diaphragm also affords powerful assistance in many of the violent muscular exertions of the body, such as strain- ing, wrestling, raising weights, &c. : by maintaining the thorax in an 300 DUBLIN DISSECTOR. expanded state it steadies the ribs, strengthens the trunk, and affords a firm support for the muscles that are engaged. We have already alluded to the possibility of diaphragmatic hernia occurring as the result of violent muscular efforts, either enlarging some of the natural openings, or bursting through some naturally weak or defective spot, or rupturing the muscle itself. Congenital deficiencies have been not unfrequently met with, but such are seldom compatible witli continued existence, though some rare exceptions are recorded ; such defects are to be considered as arrests of development, as the muscle in the very early periods of foetal life is deficient, and grows only by degrees from the circumference towards the centre. Mammalia alone possess a per- fect muscular diaphragm ; in birds it is rudimental, the pillars and cen- tral tendon being absent, and the costal fasciculi inserted into the base of each lung ; it is wanting in reptiles, fishes, and invertebrate animals. Quadratus lumborum is thick, flat, round on its outer edge, irre- gularly square, the greater diameter being from above downwards, and the outer and lower borders longer than the upper and inner, situ- ated in the lumbar region next the spine, between the ilium and last rib, forming part of the posterior wall of the abdomen, and, like the rectus muscle in front, enclosed in a strong aponuerotic sheath, formed by the anterior and middle lamina} of the tendon of the transversalis muscle, behind the colon and the kidney, the psoas and the diaphragm, and in front of the extensor muscles of the spine, and anterior to the sacro-lumbalis ; arises tendinous from the posterior fourth of the crest of the ilium, and from the ilio-lumbar ligament ; the fibres ascend obliquely inwards, and are inserted into the extremity of the trans- verse processes of the four first lumbar vertebras and of the last dorsal ; also into the internal surface of the posterior half of the last rib, be- neath the external or false ligamentum arcuatum ; the external or ilio-costal fibres are more vertical, the internal or ilio-lumbar more oblique ; these latter are usually crossed in front by another lamina of fibres, which ascend obliquely outwards from the three last transverse processes to the edge of the last rib. Use, to bend the spine to one side, to depress the last rib, and thus assist in expiration, being directly opposed to the scaleni ; when both muscles act they support the spinal column in the perpendicular direction. The complex struc- ture of this muscle gives additional strength and more varied power of action, and is analogous to the decussating laminae of the other ab- dominal muscles, or to the double layer of the intercostals, of which it may be regarded as a modified continuation. Psoas parvus, long, flat, thin, and narrow, fleshy in its upper third, tendinous below ; situated in front of the psoas magnus, and on its outer aspect above, its inner below ; arises by short, fleshy, and apo- neurotic fibres from the lower edge of the side of the body of the last dorsal vertebra, and sometimes from its transverse process, also from the body of the first lumbar, and the intervertebral substance ; the fibres descend in a direction outwards, and opposite the fourth verte- bra, end in a thin, glistening tendon, which crosses the psoas magnus, DUBLIN DISSECTOR. 301 dt-sirnds on its inner side, and is inserted broad and thin into theileo- peetin;val eminence and adjacent part of the brim of the pelvis; it is also attached externally to the iliac fascia by a broad aponeurotic expansion, which binds down the psoas and internal iliac muscles; inferiorly it is connected to the inner and back part of the crural arch, and to the pubic portion of the fascia lata behind the femoral vessels, and in front of the common tendon of the psoas and iliactis. Use, it assists in bending the body forwards, or in raising the pelvis; it makes tense the crural arch, and diminishes the aperture beneath it. This muscle is often wanting ; when present, it is connected to the psoas magnus by cellular tissue, and is partly concealed above by the diaphragm, the renal vessels, and the peritonaeum, and below by the external iliac vein and artery. Psoas ma gnus, long, round, thick in the centre, small in the extre- mities, fleshy above, tendinous below, extends along the sides of the lumbar vertebra?, the brim of the pelvis, and the anterior and inner part of the thigh. It arises by two planes of fleshy and aponeurotic fasciculi ; one large, anterior, and internal ; the other small, posterior, and external : the first arises from the side of the bodies of the two last dorsal and four first lumbar vertebrae, and from their interverte- bral ligaments ; the fibres are attached to the upper and lower mar- gins only of the vertebra?, and in the intervals to a series of tendinous arches, which are extended over the lateral grooves on these bones, to protect the lumbar vessels and the nerves which communicate between the sympathetic and the lumbar : the posterior fasciculi arise from the bases of the transverse processes. In the space between these two planes the lumbar plexus of the spinal nerves is contained, as the bra- chial plexus separates the scaleni muscles. The fibres all descend, at first vertically, afterwards obliquely outwards, along the brim of the pelvis, and, beneath Poupart's ligament, end in a tendon, which has been previously concealed among the fleshy fasciculi ; this receives the fibres of the iliacus muscle externally, and is, therefore, the common or conjoined tendon of these two muscles. This tendon descends ob- liquely outwards to about the centre of the crural arch, and escapes into the thigh beneath Poupart's ligament, in the groove between the inferior spine of the ilium and the ilio-pubal eminence; it then de- scends very obliquely inwards and backwards, being somewhat twisted round the hip joint, so that its anterior surface becomes turned in- wards, and its outer edge forwards, and is inserted into and around the lesser trochanter of the femur ; some fleshy fibres of the iliacus are also inserted into a ridge extending below to the linea aspera ; as the tendon glides round this process a small bursa is usually interposed, and a very large one always exists between it and the pubisand the fore- part of the capsule of the hip joint, and is sometimes found to commu- nicate with the synovial membrane of the latter. Use, to flex the thigh on the pelvis, or the body on the thigh; it also rotates the thigh outwards ; in standing it supports the spine, and prevents it bending backwards ; it can then, also, especially by its iliac portion, rotate the 302 DUBLIN DISSECTOK. body so as to turn its front to the opposite side; in walking it is par- ticularly engaged, raises and throws forward the lower extremit} 7 , assisted by the rectus femoris, at the same time turning the knee and foot outwards : its power is greatly increased by the reflection of the tendon over the pully-like surface of the ilium, whereby its direction becomes more perpendicular to its insertion. This muscle is situated between the psoas parvus and the quadratus lumborum above, and between the former muscle and the iliacus below ; and in the groin, between the sartorius and the pectinaeus . Its insertion is between the vastus internus and the pectinzeus, and as it extends round to the back part of the lesser trochanter, will be found to correspond to the hori- zontal line of separation between the quadratus femoris and the adductor magnus ; the lesser trochanter projects a little in this line or cellular interval, and, if the body be placed on the forepart, this insertion may be exposed posteriorly without injuring any muscle, by dividing the skin just below the fold of the natis and on the outer side of the hamstring muscles, between the tuber ischii and the great tro- chanter. The psoas is covered in the lumbar region by the diaphragm , the ligamentum arcuatum, the psoas parvus, the sympathetic nerves, the kidney and its vessels ; also on the right side by the vena cava and ascending colon, and on the left by the aorta and descend- ing colon. In the middle or pelvic division it lies between the exter- nal iliac vessels internally, and the iliac muscle and anterior crural nerve externally ; is covered by the peritonaeum, on the right side also by the ileum, caecum, and vermiform appendix, and on the left by the sigmoid flexure of the colon. The two psoae, together Avith the external iliac vessels, in this situation, overhang the margins of the pelvis, so as to diminish the transverse diameter of the upper orifice by at least half an inch ; the psoas is here also covered by the iliac fascia and the expansion of the psoas parvus ; the external iliac artery and vein are to its inner or pelvic side above, but, inferiorly, the artery is in front of it ; these vessels are connected to the muscle and its investing apo- neurosis by the fascia propria ; the anterior crural nerve is external to it, but on a deeper plane, being imbedded in the groove between it and the iliacus, and behind the iliac fascia ; in its lower or inguinal divi - sion it is partly covered by the femoral artery and vein, and by some of their branches, also by the inguinal glands, and by a considerable quantity of cellular membrane, which separates it from the fascia lata. The internal circumflex vessels follow the course of the tendon to the back part of the thigh, and separate it from the pectinaeus mus- cle. The psoas lies anterior to the transverse processes of the lumbar vertebrae, to the quadratus lumborum, the lumbar nerves, the inner edge of the iliacus internus, the ilio-pubal symphisis, the acetabulum, and the capsular ligament of the hip. The structure of this muscle is peculiar, not only in man, but in animals, as is well seen in those fattened for the table ; the fasciculi are very long and veiy tender, the connecting cellular membrane being very soft and delicate, and devoid of all fibrous and elastic tissue ; the investing sheath also is thin and DUBLIN nissi-.rroK. 303 lino. In chronic inflammation of this muscle, ending in suppuration, this >heath becomes very thick, and confines the pus as in a sac ; it is lined by organized lymph, and some pale, attenuated muscular fibres arc expanded on it ; the form of the muscle is preserved, but enlarged ; this disease is termed, "psoas abscess," and is in general connected with disease of the lumbar vertebrae, or intervertebral ligaments. Ilhu-ns inti-rmis, flat, or rather concave, radiated or triangular, iirixrs ilesliy from the transverse process of the last lumbar vertebra, ilio-lumbar ligament, base of the sacrum, the inner margin of three anterior fourths of the crest of the ilium, the two anterior spinous pro- 068868 <>f this bone, and the intervening notch, from the brim of the acetabulum and the capsular ligament, also from the iliac fossa, and from the strong aponeurosis, the iliac fascia, which covers it. This fascia is attached to the crest of the ilium and to Poupart's liga- ment as far inwards as the iliac artery, behind which it passes and becomes continuous with the pubic portion of the fascia lata; the fibres of this muscle all descend obliquely inwards, join the outer side of the tendon of the psoas magnus, and are inserted along with it, or rather into it ; the inferior fleshy fibres, which are attached to the in- ferior iliac spine and to the capsule of the hip joint, are also inserted into the anterior and inner surface of the femur, below the lesser tro- chanter; these fibres often appear as a separate muscle, which has been named ilio-capsular. Use, to assist the psoas in flexing the thigh, and in rotating it outwards ; also in abduction, it protects the forepart of the capsular ligament, and in flexion of the thigh draws it oat of the angle between the neck of the femur and the edge of the eetabolum : it fills up the concavity of the iliac fossa, some inguino- cutaneous nerves descend upon it ; on the right side it is covered by the CAC inn. on the left by the colon; in the groin it is partly covered by the sartorius, and lies upon the rectus and on the capsular ligament, anterior to the glutonis medius, and internal and posterior to the ten- sor vaginae femoris. We may next proceed to the dissection of the perineum and the viscera of the pelvis. SECTION VI. I.I. KCTION OF THE PEUINJSUM IN THE MALIC. I'LAC-K the subject on the back, bend the thighs and knees upon the trunk, and secure them in the same position as in the lateral ope- ration of lithotomy ; the dissection will be facilitated if the pelvis be rai'ial line, and detach one of them from the corpus spongiosum ure- thra, then, by examining its deep surface, its origin, particularly that which lies above the urethra, and anterior to the bulb, will be more dis- v seen. The tei : ! the anterior portions 310 DUBLIN DISSECTOR. occasionally cany along with them some muscular fibres to the dorsum of the penis, and from the attachment of the former to the suspensory ligament these fibres sometimes appear like distinct muscles, and hence, probably, Mr. Houston was led to describe a pair of muscles in this situation under the name of COMPKESSOKES VEN^E DORSALIS PENIS ; according to his account (Dub. Hosp. Rep. vol. v.) "these arise from the rami of the pubes, above the crura and erectores penis ; they ascend inwards and for- wards, unite, and are inserted in a common tendon above the dorsal vein in the median line ; they form a thin, musculo-tendinous stratum, about an inch long and three- quarters broad, separated from the penis by the dorsal vein, arteries, and nerves ; the pudic arteries, in their course to the dorsum of the penis, separate them from Wilson's mus- cles, or the anterior portions of the levatores aui. Use, to contract and close the vein, and thus, by mechanically obstructing the current of the blood, induce turgesceuce and erection of the organ." These muscles, however, which are well developed in the dog and in many other animals, do not, I believe, normally exist in man ; al- though I have, in some instances of young and robust subjects, seen the fibres above described, yet I think they are often very indistinct, and inadequate to the office assigned ; when present, I am disposed to regard them as only rudimental of the more perfect structure in other animals. TRANSVERSALIS PERIN^EI is thin and weak, often indistinct, and sometimes wanting ; it arises from the inside of the tuberosity of the ischium, above the erector penis muscle ; the fibres pass transversely inwards, but also a little forwards and downwai'ds, and are inserted into the central point of the perineum, behind the accelerator urinaj muscle. Use, to fix the central point, [and support and raise the anus ; it assists in defalcation, by pressing backwards the anus and the forepart of the rectum, which are drawn forwards and raised by the levatores ani muscles ; it may also dilate the bulb. This muscle is covered by the sphincter ani, and by the superficial fascia ; a small artery (tranversalis perinaei) runs along its anterior edge ; it lies on, or rather beneath the levator ani, and nearly parallel, connected to it by cellular membrane, and in some cases intimately joined to it ; the two transversi are sometimes continuous with each other across the median line, in front of the anus, so as to resemble a semicircle concave backwards, embracing and compressing the forepart of the rectum. In some subjects a second muscle may be observed taking a transverse course (the tranversalis alter, or ischio-bulbosus) ; this arises from the ramus of the ischium and pubis, proceeds obliquely forwards and inwards, and is inserted into the accelerator urinse and side of the bulb ; though shorter it is often stronger than the superficial trans- verse muscle ; it lies deeper and higher, that is nearer the pubis, and is partially concealed in the posterior part of the triangular or deep fascia of the perinaeum ; though not unfrequently a distinct fasciculus, it generally appears to me to be only a portion of the levator ani. The t DUBLIN DISSECTOR. 311 transversi perintvi muscles are very irregular in size in different per- sons, in some being found very distinct and strong, in others a few pale and scattered fibres only point out their course and situation ; the is frequently obliged to raise off a few fasciculi from the le- vat<>iv> uni muscles, to make even an appearance according with the description given in books. Between the three last described muscles on each side we may remark a triangular space, which is bounded ex- ternally by the crus penis and the erector penis muscle, internally by the urethra and accelerator urinae ; the base is posteriorly, and is formed by the transversalis perinsei muscle. This space contains a quantity of fat, also the perinatal artery, veins, and nerves, branches of the pudic vessels and nerves ; into this space, near its base, on the left side of the perimvum, the operator must sink his knife in the late- ral operation of lithotomy, in order to lay bare the groove in the staff. In this incision the transversalis muscle and artery of the perhueum must be divided. Next dissect oft' the erector penis from the crus penis, also the accelerators urina; muscles from the bulb and corpus spongiosum urethne ; detach the transverse muscle from its attach- ments, and remove the vessels and cellular membrane out of the tri- angular space just now described ; then press the bulb of the urethra to one side, from the crus penis, and between these two bodies we may observe a strong ligamentous substance, the fibres passing in different directions; this is the triangular ligament of the urethra, or iheinter- ii*.sr,,//s /it/ainent, or, according to some, the deep fascia of the per i- iio'inn. This is a strong aponeurosis, extended as a tense septum between the anterior part of the peruucum and the pelvis; of a triangu- lar shape, its apex is thin, and lost in front of the pubic syinphysis and subpubal ligament on the dorsal vessels of the penis ; from this it inclines obliquely downwards and backwards, attached on each side to the rami of the pubis and ischium, above the crura penis ; its base or posterior inferior margin, which is weak and undefined, is directed towards the rectum, and is connected mesially to the central point, and on either side is continued behind the transversus perimei, joins the middle perhneal aponeurosis and the ischio-rectal fascia, and is lost on the lower surface of the levator aid muscle ; it is covered on its perina-al aspect by the muscles, nerves, and vessels of the perhueuin, and by the bulb of the urethra ; the vessels of the latter are enclosed between its lamina: ; its upper or pelvic surface is in contact with a venous plexus and with the anterior portion of the levator ani ; about an inch below the pubic arch it is pierced by the urethra; this aperture correspond.-} to the angle between the bulb and the membranous por- tion of that tube, and from its margin are derived two laminae or pro- >ne, anterior and inferior, is lost upon the bulb, which it serves to fix, support, and compress ; the other, or the posterior lamina, is inure extensive, is continued backwards into the pelvis, around the membranous part of the urethra, and a delicate venous plexus, or spongy erectile tissue, and then expands to enclose the prostate gland; it is, therefore, of a funnel form, the apex towards the perineum, the 312 DUIJLIN DISSECTOR. base is in the pelvis, superiorly it covers the upper surface of the pros- tate and neck of the bladder, and is beneath the pubic ligament and the dorsal veins of the penis, and joins the convex surface of the ante- rior ligaments of the bladder, or the anterior reflection of the pelvic fascia ; laterally it forms a smooth, glistening capsule for the lobes of the pi'ostate, and is attached to the convex edge of the lateral vesical ligaments or folds of the pelvic fascia ; inferiority it extends backwards between the rectum and bladder, covers the prostate, vasa deferentia, and vesiculae seminales, and is connected between the latter to the con- vexity of the pelvic cul de sac, or recto- vesical fold of the peritonaeum ; this portion of the fascia is very distinct and strong, and has been described by Mr. Tyrrel as a distinct lamina of the pelvic aponeurosis, under the name of the recto-vesical fascia. The triangular or inter- osseous ligament is an important texture in this region ; it forms a septum or boundary to the lower and anterior part of the pelvis ; it sustains and fixes the canal of the urethra in its passage to the peri- naeum, and it supports and strengthens the bulb or the commence- ment of its corpus spongiosum ; by its attachments to the neck of the bladder and to the prostate gland, and by its continuity with the pelvic fascia, it serves to connect those organs to the pubes, and to retain them in certain fixed relations to the surrounding parts ; by its con- nexion, also, to the ischio-rectal fascia and levator ani muscle, it strengthens the inferior region of the pelvis posteriorly, and sustains this muscle and the rectum : as the pubic ligament intervenes supe- riorly between its two laminae, so inferiorly these are separated by the arteries of the bulb and by two small glands, Cowper's, or the anti- prostatic glands ; these may be next exposed by dividing a few fibres of the anterior layer of this ligament, and by a little dissection on each side of and a little below the bulb ; these are two in number, each about the size of a small pea, situated at each side of and behind the bulb, below the membranous part of the urethra, between the layers of the triangular ligament, and closely connected to the artery of the bulb ; they are covered anteriorly or inferiorly by the acceleratores urina) muscles, and by the anterior layer of the triangular ligament ; of a pale, reddish colour, and of a firm tissue, resembling that of the salivary glands ; they have no distinct capsule, and their form is there- fore variable ; from each a small, distinct duct, about an inch in length, passes forwards, and opens obliquely into the lower and lateral part of the urethra, at a little distance anterior to the bulb. Dissect away all the cellular membrane at the side of the rectum, between it and the tuber ischii ; you will thus expose the greater portion of the leva- tor ani muscle ; press the rectum to the opposite side, and you will then observe how this muscle posteriorly, and the triangular liga- ment anteriorly, close the inferior opening of the pelvis, and separate ibis cavity from the pcrinai'iun ; detach the cms penis from the bone on one side, and above it separate the triangular ligament on one side also from the rami of the pubis and ischium, and draw it over towards the bulb of the urethra, which, together with the rectum, press or fasten DUI5LIX DISSKCfOK. 313 with a tcnaculum, towards the opposite tuberosity of the ischium. In separating this ligament from the bone, the pudic artery and its ter- minating branches will be seen ; we thus also expose the greater por- tion of the levator ani muscle on one side, and which we may next examine, although, to understand the anatomy of this muscle fully, it must be examined in two other aspects ; the present dissection displays its inferior surface, the course of its fibres and their insertion or peri- mval attachment ; its upper or pelvic concave surface may be seen by raising the peritoneum and the intestines it contains out of the pelvis, and carefully dissecting the thin reflections of the pelvic fascia from its fibres ; and lastly, when the lateral dissection of the pelvis has been made (which we shall direct presently), the origin of the muscle on one side, and its relations to the rectum and neck of the bladder, will be fully displayed, in the course of which dissection the reader can again refer to the following description. LKVATOR Axi, flat, thin and broad, or irregular!}' square, situated at the inferior and lateral part of the pelvis, broader above at its origin than below at its insertion ; arises by three origins, the first is fleshy, from the posterior part of the symphisis pubis below the true ligaments of the bladder ; the second is thin and tendinous from the obturator fascia, and from the ilium above the thyroid hole, or rather from the inferior surface of that angle of reflection of the pelvic and vesical fascia?, from which both the anal and obturator lamina? de- scend external to this muscle ; its origin from the ilium is through the medium of the pelvic fascia ; the third is thick, tendinous, and fleshy from the inner surface of the ischium, and from its spi- nous process; the fibres descend obliquely inwards, by the side of the neck of the bladder and rectum ; the anterior passing more backwards than the others, while the posterior are more trans- verse or horizontal ; inserted, the anterior or pubic fibres into the central point of the perineum, and into the forepart of the rectum, uniting with the fibres from the opposite side ; these fibres descend along the side of the lower fundus of the bladder and of the prostate gland and membranous part of the urethra ; the middle fibres are in- 1 into the side of the rectum, passing internal to the sphincters, and united to the outer surface of the longitudinal fibres of the intes- tine : the posterior fibres into the back part of the rectum, and into a tendinous raphe, extending from it to the o.s coccygi.s, in which raphc the muscles from opposite sides unite, also into the two last bones of the coccyx. Use, to raise and draw forward the rectum, particularly when this intestine has been protruded by the efforts of the abdominal muscles and diaphragm to expel its contents ; it also assists in closing this intestine ; it compresses the vesicular seminales and prostate gland, and assists powerfully in the evacuation of the I'a-ces, urine, and semen ; the anterior portion supports the perimvum by raising the common central point, and may also compress and close, like a sphincter, the membranous portion of the urethra; these muscles complete the infe- rior boundary of the pelvis and abdomen, and form a muscular floor to 314 DUBLIN DISSECTOK. these regions, not unlike the diaphragm above, but opposed to it in respiration, being muscles of expiration ; they resemble a funnel, with two openings in it inferiorly, the concavity directed towards the pelvis, the convexity to the perineum, through the anterior aperture the urethra passes, through the posterior the rectum. On the perinatal surface of this muscle are placed the muscles, the triangular ligament, the anal fascia, and the adipose substance in the ischio-rectal space, of which we have already spoken, and which separates it from the obtu- rator fascia and rmiscle ; its pelvic surface is related to the bladder, prostate, and rectum, but is separated from these and from the perito- neum by the pelvic and vesical fasciae above, and by a thin lamina from the latter, which may be named rectal fascia, below. As the diaphragm owes much of its physical strength to its serous invest- ments, so the fasciculi of the levatores ani (many of which are weak and separated) are supported and connected by the aponeurotic sheath in which these muscles are enclosed on either side ; this sheath is formed on its superior or pelvic aspect by the pelvic, vesical, and rectal fascia} (but which cannot be seen in the present stage of the dissection), and on the inferior or perinatal aspect by the anal or ischio-rectal aponeurosis ; the sheath of one side is directly continuous with that of the opposite around the rectum posteriorly, and anteriorly through the intervention of the recto -vesical fascia, by which again this entire structure is attached to the triangular ligament of the urethra, and thereby maintained in such a state of tension as to afford resistance and strength to the inferior region of the perinaeum and to the parietes of the rectum. At the anterior edge of each levator ani muscle fleshy fibres may be observed to surround the membranous part of the urethra very closely. These fibres, particularly at their insertion, will in general be found so united to the levatores ani, that they may be considered as portions of these muscles; they have, however, been described differently by different anatomists, no doubt in consequence of the different appear- ances they present in different subjects, and from the different mode in which the dissection has been conducted. Mr. Wilson describes them as follows : COMPRESSORES, or LEVATORES URETHRA ; each arises by a nar- row tendon from the inside of the symphysis pubis, about one-eighth of an inch above the lower edge of the arch, and at neai-ly the same distance beneath the anterior ligaments of the bladder, to which, and to the tendon of the opposite muscle, it is connected by loose cellular membrane ; the tendons, at first round, become flat as they descend, are parallel and in contact ; they soon end in fleshy fasciculi, which separate and enclose the membranous part of the urethra, and, folding beneath it, are again united, and are inserted into a narrow tendinous line, which is lost in the common central point of the perinamm, and in the posterior layer of the triangular ligament between the prostate and the rectum. Use, to compress, contract, close, and elevate the membranous portion of the urethra : these fibres encircle the narrowest 1>L'BLIX DISSECTOK. 315 part of the urethra, that portion which is just behind the bulb, and may, by their contraction during life, form such an impediment to the passage of an instrument into the bladder as may lead the surgeon to suspect the presence of a stricture, when in reality no alteration of structure exists. The origin of these muscles is occasionally distin- guished from the levatores ani by some small veins which pass from tbe side of the neck of the bladder to join the trunk of the dorsal veins of the penis, but their insertion is confounded with these muscles in perkueo behind the bulb. To these perpendicular muscles Mr. Guthrie has added a pair of transverse compressors, arising narrow and tendinous from the rami of the ischium, they pass inwards and a little upwards, expand into a fan-like form, enclose the urethra, and are inserted into a common tendinous raphe on its upper and lower surface, extending from the prostate to the bulb, and connected to both. Mr. G. considers these Fig. 52.* * An antero-posterior section of the pelvis of a male, exhibiting the viscera in situ. 1. The bladder. 2. The prostate. 3. 3. The urethra laid open through its whole extent, 4. TheveaicolaBeminalifl laid open. 6. The bulb of the corpus spongiosum. 5. The corpus spongiosum seen both above and below the urethra. 7. The corpus cavcrnosum penis. 8. The right side of the scrotum, from which the testicle has been removed. !). The rectum. 10. The peritoneum lining the abdominal mnadea. 11. Ite reflection on the upper surface of the bladder. 12. Its reflection from the posterior surface ot tbe bladder on the rectum. !!. The section of the symphisis pubis. 14. A line marking the situation of the triangu- lar ligament. 316 DUBLIN DISSECTOK. as totally distinct from Wilson's muscles, which, according to him, descend only to the upper surface of the insertion of the transverse, and do not encircle the urethra, as Wilson and others have described. All this muscular structure is, in the adult, intermingled with a spongy, elastic, erectile tissue, and a fine, soft, adipose substance, not unlike that of the tongue, except for the preponderance of veins ; the exact course and termination or attachment of the fibres is indistinct, and appears very variable in different individuals. I consider that these perpendi- cular and transverse fibres, as well as the transversus perina;i alter, may all be regarded as portions of the levatores ani muscles, which close the pelvis inferiorly, and form a floor extending on each side from the pubis round to the coccyx ; the fibres of these thin and broad muscles are not always in close and parallel contact, but occasionally some cross others with more or less obliquity, forming imperfect but separate planes ; some fasciculi are separated by the passage of blood- vessels and by aponeurotic septa from the adjacent fasciai ; these, by careful dissection, may be still further isolated, and made to appear as distinct muscles : in the child the structure is more simple and the urethral fibres more distinctly connected with the levatores ani muscles. Let the student next replace the triangular ligament, &c., and then reconsider the several parts before him in reference to the operation of lithotomy : he has already examined the triangular space between the erector penis and accelerator urinre muscles, into which the knife of the operator is to sink in order to reach the groove in the staff; this space having been fully opened, the staff can be plainly felt or seen passing above the bulb through the membranous part of the urethra into the bladder : behind and below the bulb is the rectum ; and close to the rami of the pubis and ischium are the internal pudic vessels covered by the obturator fascia ; the large artery from the pudic, called the deep transverse artery, or the artery of the bulb, may also be observed passing in the substance of the triangular ligament, about an inch below the symphisis pubis. Hence, then, in order to lay bare the staff without injury to the more important parts which surround it, we should endeavour to open the urethra as near to the base of the trian- gular ligament as possible, as we shall thus be most likely to avoid the artery of the bulb. Suppose the knife of the operator to be lodged in the groove of the staff, and then to be pushed along it into the bladder, the student will perceive that at that moment the posterior layer of the triangular ligament, the anterior fibres of the levator ani, the compressores urethra?, and the left lateral lobe of the prostate gland, must be divided, and from this view he may also learn that the rectum will be protected from injury if the staff be well raised into the arch of the pubes, its groove turned a little to the left side, and the wrist of the operator depressed, so as to elevate the point of the knife, and thus direct it into the neck of the bladder. He may next learn in what direction the knife can be withdrawn with safety and effect, and what parts require to be divided ; it is to be withdrawn slowly mid steadily, in a direction backwards and outwards, nearly parallel to Dl KLKN DIS.sKCTOK. o 1 7 the line of the cutaneous incision, the edge so laterali/;ed as to avoid cutting the rectum posteriorly, or the pudic arteiy externally. Iii this part of the operation the middle libres of the levator ani must be divided, also the adipose substance on its perinatal surface. The stu- dent may next withdraw the staff from the bladder, and pass it again and again along the urethra into that cavity ; he will soon perceive how apt the point of the instrument is to descend into the sinus of the bulb, and the necessity of depressing the handle of the staff, in order to raise the point into the membranous part of the urethra ; at the same time he should observe that the latter is about an inch below the arch of the pubes, and that, therefore, the point of the instrument is not to be too much elevated, otherwise it may lacerate the upper part of the urethra, and injure some large veins that maybe found in this situation. The student may now also examine what occupies the space between the urethra and the pubes; immediately above that canal is the upper portion of the triangular ligament, attached to the crura penis ; behind and above this are one or two large veins from the dorsum of the penis ; these enter the pelvis along the upper surface of the prostate gland ; above these is a smooth dense ligament, the pubic liyament, which is attached to the lower edge of the symphysis pubis, and rounds off the angle between the opposite rami. Posterior to the levator arii, and overlapped by the glutaeus maxi- mus, is the following small muscle : COCCYGEUS, triangular, thin and flat, at the inferior and posterior part of the pelvis, behind and above the levator ani, and in front of the sacro-sciatic ligaments, arises narrow from the inner surface of the spine of the ischium and adjoining ligaments, the fibres expand along the inner or lesser sacro-sciatic ligament, and are inserted, fleshy and tendinous, into the extremity of the sacrum and side of the coc- cyx. Use, to support and raise the os coccygis in deiiecation, and to assist in closing the inferior and posterior part of the pelvis ; this mus- cle is between the levator ani and the glutieus maxim us ; is composed of aponeurotic and fleshy fibres ; it is more distinctly seen within the pelvis, as it is covered posteriorly by the sciatic ligaments and ghit;eu.s maximus ; its posterior margin reaches the lower edge of the pyrifor- mis, while its anterior is continuous with the levator ani, and is only distinguished from it by difference in structure ; its upper surface is concave, and in contact with the pouch of the rectum ; its lower con- vex surface is related to the gluUeus maximus muscle and to the sa- cro-sciatic ligaments. Next, let the student divide the central point of the perinautm, sepa- rate the rectum from the bulb, and draw the former a little downwards, from the bladder and piv.,t,;u.' ;:\a:id: he will thus expose the inferior or posterior surface of the neck of the bladder, the Hat posterior surface of the prostate gland, also the vesicuke semiuales, the terminations of the vasa deferentia, and the commencement of the urethra ; but the most important part to direct the attention to is a small triangular space or portion of the bladder, just above and behind the prostate gland, 318 DUBLIN DISSECTOR. which is bounded on either side by the vasa deferentia and vesicular seminales, posteriorly by the cul de sac of the peritonaeum, and ante- riorly by the prostate gland, which fonns the apex of this triangle ; all these are covered by a strong aponeurosis, the posterior layer of the triangular ligament, or the recto -vesical fascia of Tyrrel ; within this space, the bladder, when distended, is in contact with the rectum, and from the cavity of the latter the former organ may be perfo- rated during life without injuring any important part; this space is about three inches and a half or four inches from the anus, and is selected by some surgeons as the best situation for tapping the blad- der in case of retention of urine, when a catheter cannot be passed through the urethra. The student may now proceed to examine the pelvic viscera. SECTION VII. DISSECTION OF THE PELVIS. THE pelvis is the inferior portion of the trunk, continuous with and bounded above by the abdomen, with which it communicates so freely that some of the viscera of each may mutually occupy either situation; bounded on either side and in front by the ossa innominata, behind by the two last lumbar vertebra?, the sacrum, and coccyx, and closed below by the various tissues already described in the perinaeum : it is divided into the upper or false, and the lower or true pelvis ; the for- mer cannot be separated from the abdomen, as it forms an essential portion of it, but the latter is distinguished from both by a well- marked line, formed posteriorly by the promontory of the sacrum, on either side by the ilio-pectineal ridge, and anteriorly by the cristaa and symphysis of the pubes. The anatomy of the pelvis, therefore, implies that of the true pelvis, which cavity is bounded behind by the sacrum and coccyx, in front and on either side by the pubis* and ischium, and a small portion of the ilium ; the sacrum is partially lined or covered by the pyriform muscles and sciatic plexus of nerves, the pubes by the pelvic fascia, and the sides by the obturator and pelvic fascia?, the levatores ani, and internal obturator muscles. For the purpose of examining the viscera in this region, make the follow- ing dissection : separate the left cms penis, also the left border of the triangular ligament, from the rami of the ischium and pubis (if not already done), and detach the levator ani muscle of the left side from its pelvic attachments ; with the hand separate the cellular and apo- neurotic bands, which lie superior to this muscle ; then divide the sym- physis pubis, or saw the left os pubis about a quarter of an inch external to the symphysis ; divide the left ilio-sacral articulation, cut through the psoas muscle and iliac vessels, and then remove the os Dl liLIX D1SSKCTOK. 319 innominatum and lower extremity of the left side ; the pelvic viscera will remain in the concavity of the sacrum and of the os innomina- tum. These viscera will be rendered more distinct by a little prepara- tion ; first, moderately inflate the bladder through the ureter, a liga- ture having been tied around the penis, the rectum also may be moderately distended with curled hair or a sponge, and attached to the spine by a ligature. The pelvic portion of the peritoneum should be first attended to. This membrane may be now seen to descend along the sides and forepart of the rectum to within about four inches of the anus, whence it is reflected on the lower and back part of the bladder, a little above the base of the prostate gland ; the line of this reflection is, in the recumbent position of the subject, opposite the lower margin of the third piece of the sacrum ; in the erect posture it will be found on a level with the j unction of the sacrum and coccyx ; it is reflected on the bladder between the middle of the vesiculas semi- nales ; it then ascends on the back part and sides of this organ to its superior fundus, whence it is continued to the abdominal muscles. Below the line of its reflection, or below the cul de sac, we may again take notice of the small triangular space on the inferior fundus of the bladder, before alluded to, as the situation in which that viscus can be punctured from the rectum, in case of retention of urine. The reflec- tions of the peritoneum, from each side of the rectum to the back part of the bladder, are called the posterior ligaments, and the folds which this membrane forms, one on each side between the bladder and the iliac fossa, are named the lateral ligaments of the bladder ; these shall be more particularly noticed presently. The pelvic fascia may be con- sidered as a continuation of the iliac; it descends behind the iliac !s, from the brim of the pelvis, to which it adheres, lines the pari- etes of the cavity as low doAvn as the upper edge, or the origin of the levator ani muscle, and divides into two lamina?, between which this muscle is enclosed, the external is named the obturator, the internal the vesical fascia. The obturator fascia, or lateral pelvic aponeurosis, descends between the obturator internus and levator ani, adhering closely to the for- mer, and sends off the ischio- rectal or anal fascia, which covers the perinatal aspect of the levator ani muscle ; the obturator fascia is in- serted inferiorly into the projecting border, or falx-like process of the great sciatic ligament, into the tuber ischii, and into the rami of the ischium and pubis, where it is continuous with the triangular ligament of the urethra, which ligament thus appears to be the contin- uation of the obturator fascia, from one side of the pelvis to the other; it is also connected posteriorly to the overhanging border of the glut- reus maximus, and to the coccygeus muscles : its external surface is in contact above with the obturator intemus muscle, which separates it from the obturator ligament or membrane and from the bone, infe- riorly with the great pudic vessels and nerves, which it encloses in a sort of sheath, and which are thereby protected from injury in the lateral operation of lithotomy ; its internal surface is in contact above with the 320 DUBLIN DISSECTOR. levator ani muscle, but separated from it below by the anal fascia, and by the adipose mass which tills the ischio-rectal space, of which latter it forms the outer wall ; the obturator fascia is better seen in the dissec- tion of the perineum, where it has been already noticed (page 308). The vesical fascia, or superior pelvic aponeurosis, covers and adheres to the internal surface of the levator ani, lying between it and the peri- tonaeum ; in order to see it, the latter must be removed together with the loose connecting cellular tissue, which readily admits of being torn from it ; it may also be exposed on its perinatal aspect, by dividing the levator ani muscle and its investing fasciae, also the triangular li- gament of the urethra; this fascia descends, anteriorly, to the lower edge of the symphysis pubis, and laterally to a level with a line carried from this point round to the spine of the ischium ; from the pubes it is re- flected on the upper surface of the prostate gland, and on the neck of the bladder, forming the anterior true ligaments of this organ .; late- rally it is reflected from the pelvis on the side of the prostate, and on the lower part of the side of the bladder, just above the outer edge of each vesicula seminalis, and thus forms the true lateral ligaments of the bladder ; posteriorly it is thin and cellular, and lost on the fore- part of the sacrum, and on the nerves and vessels passing into and out of the pelvis. As this fascia is reflected upwards on either side to from the true lateral vesical ligaments, it encloses the vesical venous plexus, and sends off from its inferior or convex surface two processes or laminae ; one passes inwards and a little downwards, beneath the vesiculaj and the bladder, in front of the rectum, and joins a similar process from the other side ; this may be named (according to Tyr- rell) recto-venical fascia, or, if this latter be considered as derived from the posterior layer of the triangular ligament of the urethra (see p. 312), then this process may be considered as a mere connecting lamina between it and the vesical fascia; of each side ; the other pro- cess descends more directly on the upper or pelvic surface of the levator ani to the lower part of the rectum, on which it expands, and meets posteriorly the similar process from the other side, so as to invest it laterally and behind ; this process may be named the rectal fascia, and is not to be confounded Avith the anal or ischio- rectal, which covers the opposite or inferior surface of the levator ani ; the rectal fascia on either side and behind, together with the recto- vesical in front, form a complete aponeurotic investment for the lower portion of the rectum immediately above the insertions of the levatores ani muscles. The vesical fascia, therefore, on each side, may be described as dividing at the outer border of the vesicula, where it encloses a venous plexus, into three processes or lamina} : a superior, the true lateral vesical ligament ; a middle, the recto- vesical fascia ; and an inferior, the rectal fascia : at its anterior reflections it is short and very strong, and pre- sents the appearance of two flat tendons, with an intervening depres- sion, passing in an arched manner from the pubes to the neck of the bladder, and continuous with the muscular libres of the latter ; its long lateral reflection often presents the appearance of a strong tendinous DUBLIN DISSECTOR. 321 arch extending from the pubis, beneath the canal for the obturator Is, as far back as the spine of the ischium. The vesical fascia forms a pouch on each side of the bladder, which assists in closing the pelvis ; it also fixes the pelvic viscera, supports the peritonaeum, and resists the pressure of the abdominal muscles and diaphragm, and thus prevents perinaeal herniae; it separates the peri- nrcal from the pelvic or subperitoneal cellular membrane, and limits the progress of inflammation, or infiltration from the former to the latter ; its reflection on the prostate and neck of the bladder is superior to the line of the lateral incision in lithotomy through these parts, and therefore the pelvic cellular tissue is uninjured. This fascia is perfora- ted by several blood-vessels, anteriorly the small vesical and prostatic, posteriorly the sciatic and pudic ; there are also often small depres- sions and deficiencies in it filled with fat. At the anterior border of the great sciatic notch, it forms an arched boundary to the opening for the escape of the great glutaeal vessels and nerves ; when sciatic hernia occurs, it is through this opening and behind this arch. Divide the pelvic fascia on one side, in the course of its lateral re- flection, and the levator ani muscle will be exposed, particularly its origin, to the account of which the student may refer (page 313) ; the rectum, ureter, and vas deferens, also come into view, and deserve par- ticular attention ; these should be all carefully dissected, but disturbed as little as possible from their natural relations. The course of the ureter has been already described ; the vas deferens will be noticed hereafter with the generative organs ; but now remark the curved course of the rectum, its dilatation above the anus, the connexion of the peri- tonaeum to its upper and middle thirds ; and its lower third, below and wholly unattached to this membrane ; this portion is curved so as to be convex towards the prostate, concave towards the coccyx, and as the anal end of the intestine inclines backwards, it leaves between its forepart and the urethra a triangular space (recto-bulbar^ bounded above and before by the membranous portion and bulb of the urethra, behind by the rectum between the prostate and the anus ; the integu- ments, together with the central point of the perinaeum and the mus- cles inserted therein, form its base below ; this space is traversed la- terally by the knife in lithotomy, and if the convexity of the rectum, or its dilatation, be greater than usual, it is in danger of being wound- ed ; in the child, this lower curve or anterior convexity of the rectum is not developed, as the intestine is almost straight, or a little concave forwards. In the adult or old the dilatation of the rectum above the sphincters is often very considerable, particularly in front ; to it the prostate gland, vesicula3 seminales, and "bas fond" of the bladder, are connected by cellular tissue, in which a number of very large and tor- tuous veins may be observed. Next study the connexions of the urinary bladder. Vesica Urinaria is a musculo-membranous sac, the temporary re- ceptacle for the urine, which constantly trickles into it from the ureters ; 322 DUBLIN mSSECTOH. it is also the chief agent In the expulsion of this fluid from the system by the urethra, being assisted by the abdominal muscles and the dia- phragm ; situated in the median line, and, to a certain extent, a fixed viscus, its exact position and relations, as well as shape, must vary according as it is contracted or enlarged ; the latter also varies with age, and, in some measure, with sex. In the adult, in its contracted state, it is deeply sunk in the anterior and inferior part of the pelvis, behind and below the pubes, and is then of a flattened triangular form, the base towards the rectum, the apex behind the lower edge of the symphysis ; when moderately enlarged it becomes of an ovoid form, the larger end resting on the rectum, the smaller and anterior being towards the recti abdominis muscles, between the pubes and the peri- tonaeum ; when fully or over-distended the superior or abdominal end rises still higher in the abdomen, and enlarges more and more, so that the larger end of the oval is then above and the smaller end below in the pelvis. In the adult female, especially if she have borne children, the bladder has greater general capacity than in the male, is flattened before and behind as if by the pressure of the uterus and the pubes, and the transverse diameter is longer. In the infant it is pyriform, the large round end, or fundus, above in the hypogastric region of the abdomen, the small tapering neck below the pubis : this fact accounts for the term "fundus" being applied to the "summit" of the organ, which is not only inaccurate as to language, but is really incorrect, as applied to the adult, for the base or fundus is then in the pelvis : the long axis of the bladder is a line directed obliquely downwards and backwards through its cavity from one extremity to the other ; its obliquity is increased in proportion as the organ is distended and raised out of the pelvis ; it will then correspond to a line drawn from the coccyx to midway between the umbilicus and the pubes. When the trunk is slightly inclined forwards, the cervix is the most depending part ; but in the erect, and still more so in the horizontal posture, the " has fond" is on a plane inferior to the urethral opening, at least in the adult ; in the child, however, the bladder, being pyriform with the large end above, the "bas fond" is not developed, and the orifice is the most depending part. The bladder is connected to the parietes and to the viscera of the pelvis by folds of the peritonaeum, and by the reflections of the pelvic fascia. The former arc termed false liga- ments, and are five in number, viz., tivo posterior, two lateral, and one superior ; the latter are reflections of the pelvic fascia, and are four in number, two anterior and two lateral. The false ligaments are, first, the two posterior, one on each side, leading from the front of the rectum to the back part of the bladder, semilunar, concave forwards and upwards ; in each is contained the ureter posteriorly, and the obli- terated hypogastric artery anteriorly ; between these ligaments the recto- vesical cul de sac of the peritonaeum descends ; one or two semi- lunar folds usually exist on the posterior surface of the bladder, if in a state of contraction ; these disappear, however, when it expands, and 1>UIJL,IN 323 are therefore designed to admit of its more easy distension. The two lateral extend from its sides to the iliac fossae ; each contains in its dupl feature the vas deferens in the male, and the round ligament of the womb in the female. The superior ligament extends from the Fig. 53.* summit of the bladder to the recti muscles, and is partially reflected over the remains of the urachus and umbilical vessels. Detach the peritonaeum from the right iliac fossa, and gently draw the bladder and rectum from the pelvis, we shall then observe that the neck and sides of the former are retained in their situation by the reflections of * A posterior view of a transverse section of the pelvis, shewing the arrange- ment of the different layers of fasciae in the pelvis. 1. Section of the os innomi- natum. 2. Section of the upper extremity of the femur. 3. The iliacus interims and psoas muscles. 4. The divided extremity of the anterior crural nerve, ex- ternal to the sheath of the vessels. 5. The external iliac artery and vein. 6. The obturator internus muscle. 7. The internal pudic vessels and nerve. 8. The levator ani muscle. 9. The bladder. 10. The vesical plexus of veins. 11. The vesicula scminalis of one side. 12. The rectum. 13. The iliac fascia, co- vering the iliac and psoas muscles, and separating into two layers external to the vessels, so as to form a sheath for them. 14. These two layers, reuniting beneath the vessels to form the pelvic fascia, which, having descended into the pelvis, divides into, 13, the vesical fascia ; and, 1(J, the obturator fascia, descend- ing on the obturator internus muscle to the tuber ischii, and forming a sheath for the internal pudic vessels and nerve. 17. The anal or ischio-rectal fascia, given off by the obturator, and investing the inferior surface of the levator ani. 18. The vesical fascia, splitting into three laminae. 19. Its ascending lamina, forming one of the lateral ligaments of the bladder. 20. Its middle lamina, tin- ivt-to-VL'sical fascia of Tyrrell, passing beneath the vesicula? scminalcs and between the bladder and rectum. 21. Its inferior lamina, the rectal fascia, sur- rounding the rectum, and meeting the fascia of the opi .<>site side in the mesial line. Y 2 324 DUBLIN DISSECTOK. the pelvic fascia from the parietes of the pelvis upon this viscus ; these are the true ligaments of the bladder. The anterior, two in number, arise from the lower margin of the pubis by the side of the symphysis, pass backwards and upwards on the upper surface of the prostate gland, and expand on the anterior part of the bladder, with the muscular fibres of which they become partly continuous; their inferior or convex surface is united to the posterior layer of the triangular ligament ; a depression exists between them, along which the dorsal veins of the penis pass from beneath the arch of the pubes to the side of the bladder in their course to the inter- nal iliac veins ; the fascia, however, is not deficient between these ligaments, but is continued from one to the other, so as to line this depression and cover the veins. The true lateral ligaments are one on each side ; each is continuous with the anterior, and is formed by the reflection of the pelvic fascia from the inner surface of the levator ani to the side of the prostate gland and of the bladder, and encloses the vesical venous plexus. The superior anterior extremity is named the superior fundus ; the posterior, which presses against the rectum, the inferior fundus, or " has fond;" the intervening portion, the body ; and that part which is connected to the pubes, and is above the rectum, the cervix ; the latter is surrounded by the prostate gland, but little, however, of the latter being above it ; the cervix is somewhat conical ; in the adult it lies nearly horizontal, below and behind the pubes ; in the child it is more vertical or oblique. There is no exact distinction, however, between these several compartments, and a more accurate knowledge of the organ may be obtained by examining the several aspects or regions it presents when moderately distended, which are six in num- ber, and on each of which some important object may be noticed. 1st, The superior region is in contact posteriorly with the convolutions of the small intestines, and anteriorly with the recti muscles ; to it are attached the urachus and obliterated umbilical arteries ; posterior to which, only, it is covered by the peritonaeum ; if much distended, this region is sometimes found to incline to the left side. 2nd and 3rd, The lateral regions are contiguous to the sides of the pelvis, to the vesical fascia, and to the levatores ani muscles ; descending obliquely backwards along this region is the vas deferens, crossing over the um- bilical artery above, and the ureter below, passing internal to both, or nearer to the mesial line ; the peritonaeum adheres to so much of each lateral region as is posterior to the vas deferens, while that portion anterior to it is deficient of serous covering. 4th, The anterior region also looks a little downwards ; it is behind the recti muscles, the pubes, the pubic ligament, and the triangular ligament of the urethra ; all this region wants the peritonaeal covering ; towards its inferior part we observe the anterior ligaments of the bladder, between these the dorsal veins of the penis, and below these the neck of the bladder sur- rounded by the prostate gland. 5th. The posterior region is contigu- DLBI.IN DD98BCTOR. o'2o ous to the rectum in the male, to the uterus in the female, and in either sex occasionally to the convolutions of the small intestines : all lhi< ivinon is covered by peritonaeum. 6th. The inferior region, in the female, lies on the ureters and on the vagina ; in the male, on the vesicula) seminales, the intervening cul de sac of peritonaeum, the rectum, and the prostate gland ; the superior and posterior part of this region is covered by the peritonaeum ; but anterior to the line of the reflection of this membrane from the bladder to the rectum, is the tri- angular portion of tliis region, in which the peritonaeum is deficient, and wliich has been already attended to, as the situation hi which the operation of tapping the bladder from the rectum may be performed. In the contracted state of the organ, the peritonaeum descends almost to the prostate gland, and nearly covers all this space ; but hi the dis- tended state not only is the latter much enlarged, but the peritonaeum is raised out of it posteriorly, so as to allow the bladder and rectum to come hi contact. It is composed of five tunics or laminae, three of which are essential or proper, serous, muscular, and mucous ; these are connected by two laminae of cellular tissue. The serous is but a par- tial coat, covering those portions only which come into contact with other moveable viscera, namely, the posterior region, the back part of each side, and of the upper and lower fundus ; all the anterior region, the cervix, the forepart of the sides and fundus, are, therefore, unco- vered by peritonaeum ; when distended, there is more of it in propor- tion covered by this membrane than when it is contracted ; it is dense and strong, and can be easily detached from the muscular coat, to which it is connected by the first or external cellular tunic ; this la- mina, in some situations, is compact and elastic ; in others, as in front, it is loose and abundant, to allow the bladder to rise out of the pelvis ; inferiorly it contains several veins, partially envelopes the vesicula? seminales, and is continued to the forepart of the rectum ; it contains but little adipose substance ; blood-vessels and nerves ramify and divide in it in their course to the other textures ; it serves to connect the serous to the muscular coat, and to support and bind together the fibres of the latter. The muscular coat consists of fasciculi, arranged hi such different directions as to admit of partial separation into two or three lamina?, longitudinal, circular, and reticular ; they are very variable as to strength and colour, but in these respects they surpass those of other hollow viscera, except the heart and cesophagus ; the first or longitudinal are the strongest and most numerous, proceed from around the cervix, and expand over the entire surface ; those on the forepart are connected superiorly to the urachus, and inferiorly to the anterior ligaments, and through these, as by shining tendons, to the pubes ; hence some have described this lamina as a distinct muscle, " detrusor urinae," but incorrectly ; some pass deeper, and are inserted into the cellular tissue about the prostate, and some still deeper into the fibre-muscular tissue of the cervix, whereby they are enabled to expand the splu'ncter during their contraction, and so allow the escape of the urine ; laterally, these fibres are inserted into the prostate and 326 DUBLIN DISSECTOR. its investing fascia ; and, posteriorly, they are weak and scattered above, but below and between the ureters they form a strong, broad, and flat band ; several fibres are inserted into the trigone, into and around the ureters ; on the latter some even ascend in a retrograde course ; no fibres pass over the vesiculse seminales as over the prostate, but between these a distinct lamina descends to the base of the pros- tate, into and beneath which the fibres are inserted into the submucous tissue ; one fasciculus can be traced mesially beneath the uvula as far as the verumontanum, under which it is inserted by a delicate tendon; the effect of these fibres must be to depress the uvula, also to depress and retract the verumontanum, and thereby protect the latter from the irritation of the urine, and at the same time open the orifice of the urethra freely for the passage of this fluid : in the female these longi- tudinal fibres are inserted anteriorly and laterally into the cellulo- vas- cular and glandular tissue around the cervix, and posteriorly into a more dense tissue, connecting the urethra to the vagina ; the longitu- dinal fasciculi are frequently crossed by transverse and arched bands, particularly in front, where also they often decussate in the median line, and then pursue a different course ; this lamina may, by careful dissection, be raised in some places to some extent, particularly before and behind and below, but not uniformly throughout. The next order of fibres is circular ; these are pale and scattered, particularly above, but as they approach the cervix they become more close and distinct, and have been considered by some as the "sphincter vesicae," but there is no distinction between these and those above them, which are plainly designed to contract the organ ; this term, therefore, is proba- bly incorrectly applied. The circular or transverse fibres are very distinct posteriorly between the two ureters, and a strong semilunar band, concave backwards, forms the base of the trigone in front of the pouch or " bas fond," which is generally well developed in the adult and aged. This band can be better seen when the bladder is opened : it is impossible to raise these circular fibres as a distinct plane, as so many deviate from this direction and join deeper fibres in a tortuous or irregular course. The third set of muscular fibres are best seen from the internal surface ; they project through the mucous mem- brane as distinct fasciculi, large and separate, and most irregularly arranged, so as to present a reticulated or honeycomb appearance"; they are often very large, and, though paler, are not unlike some of the carnese columns of the heart ; they take various directions, divide, join again, subdivide, and unite with some of the other planes ; when hypertrophied, these fibres often project considerably into the cavity, causing proportioned depressions or pouches of the membrane between them. This condition is named the columnar bladder, and the pouches, which often become dilated, like offsets with narrow, con- stricted mouths, are true hernias of the mucous coat. This condi- tion is named the sacculated bladder. In these sacs calculi are some- times lodged, and one of them, may undergo such gradual enlargement and lateral elongation as to become engaged in femoral or inguinal DUBLIN DISSECTOll. 327 hernia. The neck of the bladder presents a peculiar structure ; there is no exact limit to this part, hence the tenn is differently applied by different writers : some include as cervix all that portion in front of the recto- vesical reflection of peritonaeum ; others consider it so much only as is surrounded by the prostate gland ; but most regard this as the first division of the urethra. There is, therefore, no exact limit or external mark to define this part, although it is one so generally alluded to. We consider as the neck that contracted, conical portion of the viscus, longer below and on the sides than above, which is em- braced inferiorly and laterally by the base of the prostate gland, and laterally and above by the peculiar contractile structure which fulfils the office of a sphincter ; this part contains internally and below, the slight elevation called the uvula or " luette," which lies over the mid- dle lobe of the prostate gland ; the contractile tissue is muscular, also fibrous and elastic, as well as vascular and nervous; it surrounds three- fourths of the orifice ; the muscular fibres are red and close, are attached to the fibrous basis of the trigone on each side of the uvula, behind which they do not pass ; they are not continuous with the cir- cular plane, but the longitudinal fibres are partly inserted into this semicircular muscle, in the same way as the levatores intermingle with the sphincter ani ; it is partly elastic, but essentially muscular ; bounds the urethral opening laterally and above, but not below : the slight projection of the uvula in the latter situation, and the elasticity and tonic contraction common to all sphincters, preserve the opening in a closed state, and the urine is thus retained in the bladder, the muscular coat of which is in a passive and relaxed state ; when distension ex- cites the usual feeling, the general muscular coat contracts towards the pubis and cervix, and the longitudinal fibres draw out from the axis of the opening the relaxed sphincter which encompasses three- fourths of it, while the long middle band will depress the uvula and retract the seminal caruncle, and thereby free the passage into the urethra. At the anterior part of the inferior region there is a com- pact laver of white, dense, fibrous substance, into which the muscular, particularly the longitudinal, fibres of the bladder are inserted, but which itself does not appear to be very muscular, except near the cer- vix : this structure will be found to correspond with a particular region, to be noticed presently, in the interior of the bladder, called the tri- gone, or velum. Beneath the muscular is the fourth, or the deep cel- lular coat ; it invests the whole organ, is very elastic, and seldom con- tains any adipose substance ; it supports and strengthens the mucous lining, and contains the nutrient vessels and nerves. Open the blad- der by a perpendicular incision through its anterior part, and the fifth, or mucous coat, will be observed, pale, and thrown into many folds, chietly transverse, particularly if the bladder had been empty, for this membrane has no contractile power 5 through it the muscular fibres project, presenting a reticulated appearance, and very frequently the mucous membrane forms pouches, or small sacs, between these : infe- 328 DUBLIN DISSECTOR. riorly is seen the orifice of the urethra, somewhat of a crescentic figure, the uvula projecting into it from below ; posterior to this the mem- brane presents a smooth and dense appearance through- out a small triangular space called the velum or trigone ; at the posterior angles of which are the orifices of the ureters ; the line extending between these forms the base of this triangle, is somewhat semilunar, and contains strong muscular fibres ; the sides are defined by lines drawn from each ureter to the uvula from an inch to an inch and a half in length ; beneath the membrane co- vering these, pale muscular fibres may in general be found ; these have been named by Mr. Bell the mus- cles of the ureters, who de- scribes each as arising from the vesical extremity of the ureter, and thence descend- ing obliquely forwards and inwards, to be inserted by a tendon common to its fellow into the uvula. The use which he assigns to them is, to restrain the termination of the ureters, and preserve the obliquity of the passage of these tubes through the coats of the bladder while it is being contracted ; for, says * The urinary bladder and canal of the urethra laid open. 1. The mucous coat of the bladder thrown into folds. 2. 2. The ureters. 3. 3. Their orifices at the posterior angles of the trigone. 4. The base of the trigone. 5. The uvula. 6. 6. The prostate gland. 7. The prostatic portion of the urethra, the figure is placed on the verumontanum. 8. The membranous portion of the urethra. 9. 9. The antiprostatic glands, or glands of Cowper. 10. 10. The bulb of the urethra. 11. The spongy portion of the urethra, the figure is placed on the sinus of the bulb. 12. The fossa navicularis. 13. The orifice of the urethra. 14. 14. The corpus spongiosum urethra. 15. The corpora cavernosa penis. 16. 16. The vasa deferentia. DUBLIN DISSECTOR. 329 ho, without this provision, the urine would be sent retrograde into the ureters, instead of forward into the urethra. These lines, however, seldom present this structure so distinctly as has been described, and how far their supposed use is correctly ascribed to them is very ques- tionable.* The uvula is a small eminence at the apex of the trigone, much better marked in some than in others ; nearly opposite, but a little anterior to the third or middle lobe of the prostate gland, it appears little more than a slight fulness or prominence of the mem- brane, with an increase in the submucous tissue, which contains some follicles ; it is vascular, and probably possesses some special organiza- tion, which endows it with peculiar sensibility and associates it with the entire organ ; it assists in closing the urethral opening, but is effaced in a great measure by opening the cervix from the urethra when the bladder has been removed from the body, as the membrane is easily extended ; but if only a small opening be made in the upper part, and we then look down towards the urethra, it appears as a small eminence in the median line, which it thus assists to close : it is smaller in the female ; hence the urethral opening is larger than hi the male. Throughout the area of the trigone the membrane is free from rugae, but often marked with fine striae, which converge to the urethral orifice, giving to the latter a puckered appearance. It usually presents a delicate rose tint, being variegated with fine vessels ; with the aid of a magnifying lens numerous villi can be detected ; it appears deli- cately and peculiarly organized, and is, no doubt, the most sensible part of the internal surface ; beneath it is a dense substratum of fibro-cel- lular tissue, exterior to which the longitudinal muscular fibres are very distinct, and many are inserted into it, but very few of the cir- cular or reticular can be detected ; it is also supported by the vasa deferentia, vesiculae, and prostate ; this portion is so firm and incom- pressible that the cavity corresponding to it cannot be wholly oblite- rated, so that in the most perfectly contracted state it will still retain a few drops of urine ; posterior to it the bladder is frequently, particu- larly in old subjects, dilated into a sort of pouch, which rests upon the rectum, and is so much below the level of the trigone that it is neces- sary, when sounding the bladder for the detection of a stone, to raise the handle of the instrument, and thus depress the point into this space, or the finger introduced into the rectum may raise forward this pouch, and thus strike the stone against the sound. In the female the trigone is smaller, less firm and distinct, but broader hi proportion, than in the male, and the uvula is less developed. The vesical arteries are variable as to origin, number, and size ; they arise from the internal iliac, pudic, and obturator ; the veins form a remarkable plexus around the cervix, which extends along the sides of the inferior fundus and vesiculse seminales, and opens into the internal iliac, or some of its branches ; the nerves are derived both from ganglionic and spinal filaments of the hypogastric plexus ; ac- * See art. " Bladder," Todd's Encyclop. of Anat. and Phys. 330 DUBLIN DISSECTOR. cordingly the muscular power is partly involuntary and partly under the influence of the will. This organ is by no means essential to the urinary secretion, and is absent in many animals ; it is merely intended as a reservoir for the urine, and to act in its expulsion, in which it is the chief agent, for when its muscular coat is in a state of paralysis the most violent action of the abdominal muscles and diaphragm is unable to empty it of its contents. The bladder is occasionally found in a diseased state ; inflammation of it (cystitis) may be general or confined to one particular part ; the portion which is most frequently so affected is that near the neck, and commonly arises from the presence of a rough stone : from the natu- rally pale appearance of the mucous membrane in the dead body any crowding of vessels containing arterial blood which takes place in in- flammation, makes this state of parts easy of detection, and this is the case in chronic inflammation or catarrh of the bladder : if the inflam- mation be violent, the muscular coat may become engaged, and ab- scesses and ulcers are not unfrequently the consequence ; they some- times proceed so far as to destroy a portion of the bladder, and form communications between it and the neighbouring viscera ; with the rectum in the male, and vagina in the female 5 they have also been known to open into the cavity of the abdomen, producing peritonitis and death from extravasation of urine ; abscesses about the ne.ck of the bladder are generally found as a consequence of the operation of lithotomy or of fatal retention of urine, or diseased prostate gland. The uvula, like other similar portions of mucous texture, is subject to infiltration and increase of size in acute inflammatory affections, as also to chronic enlargement, and closely simulates disease of the mid- dle lobe of the prostate gland. Calculi are not uncommonly formed in the bladder, their formation is confined to no particular period of life; they are found in very young children and in persons of middle and ad- vanced age ; they are less frequent in females, as the size of the urethra in that sex allows them to be discharged before they become large, probably also the tendency to their formation is not so strong. The stones which are found in the bladder are either originally formed in the kidneys, and pass through the ureters into the bladder, or they are at first formed in the bladder itself. Calculi lie either loosely in the cavity, or are confined to some fixed situation from particular cir- cumstances ; when they are of a small size they are sometimes lodged in pouches, formed by the protrusion of the mucous coat between the muscular fasciculi. Urinary calculi have sometimes a smooth, uniform surface, but more frequently they are granulated and rough. The urethra is the next division of the urinary organs to be exa- mined ; as this canal, however, in the male, is the common passage for the urine and semen, and a part both of the urinary and generative organs, we shall postpone the description of it until we have consi- dered the latter. DUBLIN DISSECTOK. 331 SECTION VIII. DISSECTION OF THE ORGANS OF GENERATION IN THE MALE. THESE are the testicles and their appendices, the vesiculae semi- nales, the prostate and anti-prostatic glands (the latter have been already examined), the penis, and the urethra. The testes secrete the seminal fluid, the vasa deferentia conduct this to the vesicular se- minales, whence it is conveyed, together with the secretion of these organs, by the ejaculatory ducts, into the urethra ; the secretions from the prostate and antiprostatic glands are added to it, but equally belong to this canal as a common passage for the urine, as well as semen ; finally, the urethra is enclosed in a spongy erectile tissue, to which is added the analogous structure of the two crura penis, whereby it is adapted for the final expulsion of the seminal fluid. We shall describe these organs in the following order : 1st, the testes with then: coverings ; 2nd, the vasa deferentia ; 3rd, the vesiculae serninales; 4th, the prostate gland ; 5th, the penis ; and 6th, the urethra, 1st. The Testes These two glands are, during the greater part of uterine life, contained in the abdomen beneath each kidney ; some time, however, previous to birth, they descend into that situation which they are found to occupy in the adult, and are surrounded by several tunics, viz., the scrotum, dartos, superficial fascia, tunica coin- mums, vaginalis, albuginea, and vasculosa; the three first are common to both, the others are proper to each testis. The Scrotum is a loose process of integument continued from the inner side of each thigh, and from the perinseum and penis ; it is gene- rally of a dark brown colour, thinly covered with oblique hairs, the white bulbs of which project upon the surface ; it usually presents numerous wrinkles, and is so thin that the subcutaneous veins and sebaceous follicles can be seen through it ; these latter secrete the pe- culiar perspirable matter of this region ; the prominent hard ridge or raphe is continued from the perimeum along its middle line as far as the penis. In the old and enfeebled, or under the influence of warmth, it is soft, flaccid, and elongated ; but in the robust, or when exposed to cold, it becomes rugous and closely contracted around the testes, and deeply indented between them ; certain mental and nervous emo- tions also induce similar changes, which most probably depend upon the action of the subjacent tissue, the dartos, rather than upon the skin itself. The Dartos is the peculiar cellular tissue immediately subjacent to the skin ; it usually presents a reddish appearance ; a number of small Is are distributed through it; its texture is very loose, and is readily distended in emphysema, or hi anasarca ; it never contains any fat ; it is somewhat more dense in the mesial line than at either side, is connected to the rami of the pubes and ischium, and to the raphe in the middle, thence it ascends a short way between the testes to the 332 DUBLIN DISSECTOR. urethra, and thus assists the superficial fascia in forming the septum scroti, which divides this pouch into two lateral portions, of which the left is generally the longer ; some describe the dartos as double, one for each side ; the dartos manifests during life a degree of contractility above that which cellular tissue enjoys in any other situation ; it pos- sesses the power of corrugating the skin, and moving the testes in a sort of vermicular or peristaltic manner, distinct from the upward motion of these glands produced by the cremaster muscles ; anteriorly and laterally it ends abruptly in the cellular and adipose tissue of each femoral and inguinal region ; in the middle it is continued round the penis, and can be sometimes traced even to the prepuce ; posteriorly it extends near to the anus, and often derives a few muscular fibres from its sphincter : it is composed of thin areolar tissue, traversed by nerves and vessels, and intermingled with fine, soft, reddish filaments, which are interlaced in an irregular manner ; some fibres are trans- verse, but the most are vertical ; these resemble the involuntary mus- cular fibre in being unstriped, and in the effect of acetic acid bringing into view the peculiar corpuscles they contain, and which distinguish them from the white and yellow fibrous elements of the areolar tissue : the dartoid then appears to be a peculiar tissue, intermediate between cellular and muscular: a somewhat analogous texture most probably pervades certain other parts, viz., the vagina, the nipple, the coats of some excretory ducts and blood-vessels ; the dartos exists in the scro- tum before the descent of the testes, and cannot therefore be derived from the expansion of the gubernaculum testis, as some have sup- posed. Beneath the dartos is the superficial fascia of the scrotum, con- tinued from that of the abdomen around each spermatic cord, testicle, and epididymis, thin, loose, and reticular, it becomes continuous with the fascia of the perinseum ; as it envelopes the cord and testis on each side, it assists the dartos in forming the septum scroti, and retaining each testicle at its own side ; it is very distinct above towards each inguinal ring, also posteriorly where it enters the perinoeuin, but in the intermediate space it is a mere cellular connexion between the dartos and the next covering of the testis. Some anatomists, there- fore, include this tissue in their account of the dartos, and do not con- sider it as a separate lamina of the scrotum. The tunica communis, or erythroides, or musculosa, is a compound tissue ; it commences in the inguinal channel, is composed essentially of the cremaster muscle, very variable in strength and colour, consisting superiorly of two or three fasciculi, which descend on the outer and forepart of the cord, expand and separate on the testis in curved or arched lines, concave upwards, and inserted partly into the tunica va- ginalis, and partly by re-ascending fibres into the cord and pubis (see page 195) ; the fasciculi are covered and bound together by a fascia derived from the deep aponeurosis of the abdominal muscles and from the pillars of the external ring (intercolumnar or spermatic fascia) ; internally they are also connected by a fine membrane derived from DUBLIN DISSECTOR. 333 the edges of the internal ring (the infundibuliform fascia from the transversalis), and from the cellular tissue in the canal ; the two for- mer components of the tunica communis expand all round the testis, but the latter being closely attached to the vessels of the cord adheres to its upper and back part and to the epididymis, and does not, there- fore, properly cover the gland : this tunic is the chief means of sus- pension of the testis, while the cremaster also draws it upwards and outwards, supports and compresses its vascular texture, and urges its secretion through the vas deferens : in old hernia and hydrocele it sometimes acquires prodigious strength and thickness ; the influence of these diseases upon this structure, however, is very variable. The tunica vaginalis, or serosa, was originally, that is, in foetal life, a process of the peritonaeum, having been prolonged in front of and around the cord and testis, as the latter was descending from the abdomen to the scrotum ; at this age the tunica vaginalis freely com- municated with the cavity of the peritonaeum by a canal which led along the forepart of the cord from the abdomen to the scrotum : this canal, however, previous to birth, was closed by the adhesive process, and ever afterwards the cavity of the tunica vaginalis is distinct from that of the peritonamm.* The tunica vaginalis, therefore, is a serous membrane, a shut sac of an oval form, suspending and partly enclos- ing the testicle, and also reflected over its anterior part and sides, and larger than the gland, as it also encloses a portion of the epididymis and of the cord ; that portion of it which suspends the gland, and which lines the scrotum, may be named the tunica vaginalis scroti, or parietal layer, while the reflected portion, which covers the sides and forepart of the testicle, is the tunica vaginalis testis, or visceral layer. This membrane is so loosely connected to the scrotum that it can be detached from it with little force ; it is thence reflected on the sides and forepart of the epididymis and testis ; it also ascends a short dis- tance on the forepart of the cord, higher upon its inner side, and sepa- rated from the epididymis by the vas deferens and the spermatic vessels ; the posterior part of the epididymis is altogether uncovered by it : as it is continued from the epididymis to the testicle it passes in between these organs on their outer side, so as to form a sort of pouch or cul de sac between them. Both the testicle and epididymis are in reality behind this serous membrane, and nothing is contained within its cavity except the serous fluid which lubricates its opposed surfaces, and which facilitates that gliding motion which the testicle undergoes in the scrotum ; hence in hydrocele, or dropsy of this sac, the testis is almost always at the upper, inner, and back part of the tumour. When the anterior part of the tunica vaginalis is divided, we see its internal surface smooth and polished ; shining through its reflected layer which covers the testis, we can discern the next, or the fibrous tunic of the gland, to which it adheres very intimately, * When tliis canal is not thus closed, a hernia usually occurs, which is named " congenital inguinal hernia." In most animals it communicates with the ge- neral peritonaeum at all ages. 334 DUBLIN DISSKCTOK. forming with it a true fibre-serous membrane like the pericardium or the dura mater : the tunica vaginalis serves to insulate the testis from adjacent parts, and to facilitate those gliding motions which enable it to elude injury or pressure. Tunica albuginea is a dense fibrous membrane, of a bluish white colour ; the proper capsule of the gland, adheres to it, preserves its form, and sends several processes or septa into it, which will be seen when it has been divided ; it has no connexion to the epididymis ; the reflected layer of the tunica vaginalis is intimately united to it ; through it the blood-vessels of the vascular coat can be distinctly seen ; having invested the whole gland, it is inflected into it poste- riorly in the form of a vertical plate or partition, composed of two laminae, one from either side, enclosing between them the vessels, nerves, and ducts ; this is the corpus Highmorianum or mediastinum testis ; from its anterior or visceral border numerous bands radiate for- wards, inwards, and outwards, and adhere to similar processes from the inner surface of this coat ; these are the septa or desipimenta testis, which divide the organ into so many compartments, conduct the vessels to and fro, preserve the form of each, and protect the glan- dular contents from compression ; in the mediastinal process the blood- vessels are most distinct posteriorly, the seminal ducts anteriorly. Tunica vasculosa, so named by Cooper, is an extremely delicate membrane, and in immediate contact with the glandular tissue, com- posed of minute but tortuous ramifications of the spermatic vessels, united by a fine cellular web ; it lines the albuginea, and is so thin in some places as scarcely to deserve the name of a distinct membrane ; it not only envelopes the sur- face, but also sends in delicate membranous processes along each of the septa, which convey the nutrient vessels to the lobules of the gland. Each testicle is of an oval form, flattened on each side, also a little on the back part beneath the epididymis ; it is suspended rather obliquely, the superior extremity being directed forwards and outwards, the inferior backwards and inwards ; the left is a little lower than the right ; hence, when the thighs are crossed, these glands do not approximate so closely, thereby they escape compression ; bent like an arch, along the * A section of the testicle. 1. The cavity of the tunica vaginalis ; the external layer is the tunica vaginalis scroti, and the internal, which covers the testicle, is the tunica vaginalis testis. 2. The tunica albuginea. 3. The tunica vasculosa, or pia mater testis. 4. The corpus Highmorianum, or mediastinum testis, shew- ing the rete testis between its lamina; and the fibrous septa which connect it to the internal surface of the tunica albuginea. 5. 5. The convolutions of the tu- Intli scminiferi, terminating in the tulmli rocti. fi. The epididymis. Fig. 55.* DUBLIN DISSECTOK. 335 posterior surface and external aspect of each, is the cpididymis, long and narrow, large above (globus major), narrow in the middle (body), and again enlarged below (globus minor), attached to the testis above by vessels, and in the rest of its extent by the reflected layer of the tunica vaginalis, closely on the internal, but very loosely on the external or femoral side ; from its inferior extremity the vas deferens proceeds, and thence ascends along its internal side. Divide the tunica albuginea anteriorly, and we observe the testicle to be composed of a soft, greyish, or yellowish pulpy substance, which, when opened out a little and floated in water, is found to consist of numerous fine, tortuous shreds or vessels of delicate texture, loosely connected to each other ; some are of considerable length, and with a little care may be drawn out of the gland to the extent of two or three feet, pre- senting at first a knotted or beaded appearance, owing to the coils or convolutions ; they are placed in packets or fasciculi, which are sepa- rated from each other by fibrous bands or septa, derived from the tunica albuginea, and which may now be seen to pass in considerable number through the gland towards the back part to join the corpus Highmorianum, which is broader above than below, and perforated in the former situation by the excretory ducts. These packets or bun- dles of tubes are the lobules of the testis, between three and four hun- dred in number ; each is of a flattened, conical form, the base towards the surface, the apex posteriorly towards the mediastinum, enclosed in two membranous capsules, one from the tunica albuginea, the other from the tunica vasculosa, and composed either of one or of a mass of convoluted tubuli seminiferi, with minute blood-vessels ; some tubes appear larger than others ; their average diameter is the 1 ^ 5 part of an inch, and occasionally they receive injection from mercury, but seldom admit any fine- coloured fluid ; in each lobule these tubes commence or terminate either in anastomosing loops or in free caecal ends ; their con- volutions also appear to communicate ; but the tubuli in one lobule do not directly inosculate with those in another, hence mercurial injec- tions are often but partially successful, some of the lobules only being filled ; the tubes are less convoluted posteriorly, where several coalesce, and they all terminate in about twenty larger and less convoluted vessels, which proceed in parallel lines towards the back part of the gland ; these are the tubuli recti ; they enter the mediastinum, and if one lamina of this process be raised off, they will be seen entangled with each other, and with the vessels and nerves of the gland ; this latter structure is named Retc Testis, is placed near the posterior part of the gland, between the lamina of the mediastinum ; from the upper part of it about eight or ten tortuous vessels ascend obliquely back- wards, pierce the tunica albuginea, and arrive at the head of the epi- didymis ; here they increase in size, and become coiled or convoluted ; these are the vasa cfferentia, or coni vasculosi : they form the head or globus major of the epididymis, and unite into one small duct (the vas deferens), which is twisted and coiled over and over again in a most extraordinary and peculiar manner. The body and globus minor arc 336 DUBLIN DISSECTOR. solely composed of this convoluted vessel, which by care may be unra- velled to a great extent ; some coni vasculosi, or coiled seminal ducts, continue from the head through the body of the epididymis, and end in the vas deferens ; the convolutions of this latter, of which the epidi- dymis thus principally consists, are connected to each other by fine cellular tissue, and by the reflected tunica vaginalis ; it has no fibrous capsule like the testis ; from its lower extremity the vas deferens at length escapes, and, increasing in size and density, this duct bends upwards along the inner side of the epididymis ; a little above the head of the latter it becomes a part of the spermatic cord, and is connected to the spermatic vessels and cremaster muscle behind, and distinct from both ; with these it continues its course obliquely upwards and outwards along the inguinal channel, and through the internal abdo- minal ring ; it here separates from the spermatic vessels, the latter ascending towards the spine, and passes backwards, inwards, and downwards, enclosed in the lateral fold of peritonaeum, which conducts it to the bladder, along the side and inferior fundus of which it runs internal to the vesicula seminalis, and converging to its fellow : at the base of the prostate gland each vas deferens joins obliquely the duct of the corresponding vesicula, the union of which forms the ductus eja- culatorius communis, which runs through the prostate obliquely for- wards and inwards, and opens into the prostatic portion of the urethra on the side of the verumontanum. While the vas deferens is con- tained in the spermatic cord, it lies posterior to the spermatic arteries and veins, and to the cremaster muscle ; as it passes through the inter- nal ring it hooks round the outer side of the epigastric artery, being separated from it by the spermatic artery alone ; it next passes over the psoas and iliac muscles, the external iliac artery and vein ; it then bends over the obliterated hypogastric artery and descends internal to it ; and in the same manner it next crosses over the ureter, so as to lie at first anterior to that tube, or between it and the bladder, and then to descend along its internal side ; it then runs between the bladder and rectum, near to its fellow, and internal to the vesicula seminalis, as far as the prostate gland, which it perforates in the direction before mentioned. This vessel has a peculiar, hard, wiry feel, like whipcord ; its cah'bre is very small ; its coats are two in number, an internal mu- cous, and an external very thick, firm, and white, like fibro-carti- lage ; the mucous surface is pale, rough, and alveolar, but very thin ; the external coat is most probably fibrous, the fibres being principally circular; their true character is not ascertained in man, but in some animals the fibres are longitudinal and circular, and apparently mus- cular. Between the vesiculse each vas deferens is flattened, enlarged, and often convoluted ; when it enters the prostate it again contracts, and its firm external tunic ceases. In some a second duct, vasculum aberrans, will be found to leave the testis or the epididymis, and to run for some distance parallel to the vas deferens, which in some cases it will join, while in others it will be found to end in a cul de sac, The spermatic cord extends from the epididymis to the internal ab- ]>rni.ix mssKrTOR. 337 dominal ring ; it consists of the vas deferens, spermatic artery, veins, nerves, and lymphatics ; this fasciculus of vessels is covered by loose cellular membrane, and by the cremaster muscle : beneath the latter and the fascia which supports it, the vessels of the cord will be found joined together by a fine membrane, named the tunica vaginalis of the cord; this is the remains of that portion of peritonaeum which in the foetus accompanied the spermatic vessels to the scrotum, and which after birth lost its serous characters, and became converted into con- densed cellular membrane ; this covering is strengthened by the pro- longation of the fascia transversalis which is continued from the inter- nal abdominal ring along the spermatic vessels. The spermatic artery arises from the abdominal aorta below the renal artery, and not unfrequently from the latter; it descends along the psoas muscle, passes through the internal abdominal ring on the outer side of the epigastric artery ; it then enters the spermatic cord, is conducted to the back part of the testicle, and divides into several branches which enter the rete testis ; these subdivide minutely as they proceed into the substance of the testicle, in which they twine around the tubuli semi- niferi and the spermatic veins ; one or two small arteries from the epi- gastric are distributed to the cremaster. The veins, when they leave the rete testis, twine around the arteries, and then ascend in the sper- matic cord ; a little above the testicle these vessels become very tor- tuous, and form a plexus, which is named Corpus Pampiniforme ; the spermatic veins then accompany the spermatic artery through the inguinal canal and along the psoas muscle towards the spine : the right spermatic vein generally ends in the inferior cava near the entrance of the right renal vein ; the left frequently ends in the left renal vein. The nerves of the testicle are derived chiefly from the spermatic plexus, which is formed by the union of branches from the lumbar ganglions of the sympathetic, with filaments from the splanchnic nerves and from the renal plexus ; the cremaster muscle is also sup- plied by branches from the lumbar plexus of spinal nerves, hence this muscle is, to a certain extent, voluntary. The vesiculce seminales are twc membranous sacs of variable size, situated on the inferior surface of the bladder, behind and above the prostate gland, on the outer side of the vasa deferentia, and anterior to the rectum, converging before, diverging behind, connected to the bladder by filamentous tissue, surrounded by venous plexus, and forming the sides of the triangular space, which is completed by the prostate gland, and by the recto- vesical fold of peritonaeum ; each is of an oval figure, about two inches long and half an inch broad ; the supe- rior and posterior extremity is large and round, and in contact with the ureter ; the anterior is narrow, connected to the prostate gland, and ends in a small duct which joins the vas deferens ; the union of these forming the common seminal or ejaculatory duct, which is about three quarters of an inch long, and passes obliquely forwards and inwards through the prostate gland, between its middle and lateral lobes, and opens into the urethra by the side of the anterior extremity of the 338 DUBLIN DISSECTOR. verumontanum. Although the vesiculae look like a congeries of cells, yet by dissection they may be unravelled, so as to appear as one con- tinued tube convoluted or coiled very much, the different coils com- municating with each other ; these organs are covered by a dense fascia, which is continued from that covering the prostate gland. Each vesicula consists of two tunics, viz., mucous membrane inter- nally, and peculiar grey substance externally, somewhat similar to, but softer than the outer coat of the vas deferens. The vas deferens communicates very freely with the corresponding vesicula ; hence air or fluid injected into the vas deferens will often distend the vesicula seminalis of the same side before it escapes into the urethra by the common ejaculatory duct. These organs are generally believed to contribute some additional secretion to the seminal fluid, rather than to serve as reservoirs for the latter ; their exact use, however, is not well known ; they are wanting in many animals. The common seminal or ejaculatory ducts are thin, the external coat of the vesi- culaa and of the vasa deferentia cease, and these canals appear to be formed of little more than a fine mucous membrane ; their calibre is larger and more dilatable than those of the vesiculse or testis. The prostate gland is situated at the anterior and inferior part of the pelvis, behind the triangular ligament, and in front of the rectum, to which it is connected by cellular membrane ; it surrounds the neck of the bladder and about an inch and a quarter of the urethra; is at- tached and nearly fixed in its position by the anterior ligaments of the bladder to the lower edge of the symphysis pubis, from which it is about three-fourths of an inch distant, also by the posterior lamina of the triangular ligament, which encloses the membranous part of the urethra, and expands around tin's gland ; it is also surrounded by several veins. The prostate is somewhat chesnut or heart-shaped, or triangular ; the base is posterior, and connected to the vesiculaj semi- nales ; the apex is anterior, and extends to within a short distance of the triangular ligament ; in the erect posture its long axis is nearly horizontal, sloping a little downwards and forwards, but in the recum- bent it is the reverse, the base being on a lower level than the apex : only a small portion of it lies superior to the neck of the bladder and urethra ; this part is convex, and is covered by the dorsal veins of the penis, and by the anterior ligaments of the bladder ; the inferior or posterior surface is almost flat, a slight groove is generally observable on it, extending along the mesial line ; this surface is attached to the forepart of the rectum, and may be felt distinctly either in the living or in the dead subject by the finger introduced into the intestine about two inches and a half above the anus ; the sides of the gland are smooth, very round, and covered by a strong fascia, by several veins, and by the levatores ani muscles ; the relation of the urethra to the prostate varies, in general it is one-third nearer to its upper than its lower surface ; in some the gland is absent above, and the urethra may be said to groove it only ; in others it forms a cylinder around the canal, wider in the centre than at the ends ; and in some rare nrni.ix DISSKCTOK. 339 cases it has been found thicker above the urethra, being separated from the rectum only by a thin lamina. In the base or posterior end is a notch for the entrance of the common ejaculatory ducts; this notch, together with the groove on the posterior surface, and the passage of the urethra above this, have caused it to be described as consisting of two lateral portions, called the right and left lateral lobes ; these are connected to each other posteriorly by a small transverse process called the middle lobe ; the latter may be seen by detaching the vesi- cular and vas deferentia from the bladder, and leaving them suspended by their common ducts, the middle lobe of the prostate will then be seen to pass from one lateral lobe to the other, and to be closely con- nected to the mucous membrane of the bladder, and above the ducts : the bilobed appearance of this gland is more distinct in animals than in man. The prostate has a firm, resisting feel, a greyish colour, and a very compact structure ; these characters, however, chiefly depend on the strong fascia which invests it, and which forms its capsule : the cap- sule has been already described as being partly derived from the pos- terior layer of the triangular ligament, which expands on the sides and inferior surface of the gland, and partly from the reflection of the pelvic fascia from the pubes, called the anterior ligaments of the blad- der. Next continue the incision, which was made in the forepart of the bladder, through the upper part of the prostate, so as to lay open the urethra ; we shall perceive how this gland surrounds the canal, also the greater thickness of its lateral portions. The prostate gland consists of several follicles or acini closely connected to each other, and covered externally by the capsule, and internally by the mucous membrane ; a reddish, filamentous tissue also pervades it, which appears of a fleshy nature, and continuous with the muscular fibres of the bladder ; these follicles open by several small ducts, ten or twelve on the lower surface of the urethra, in two lateral depressions, called prostatic sinuses, on either side of the verumontanum ; some small ducts also open on the upper surface of the canal ; a white, brownish, viscid fliu'd can be squeezed from these small openings ; the contraction of the bladder and of its sphincter, with that of the levatores ani mus- cles, no doubt express this fluid from the gland to lubricate the urethral canal. The prostate is absent in the female, and small and tender in the male, previous to puberty. The Penis is situated in front, and connected to the symphysis pubis ; is divided into its root or roots, body, and extremity or glans ; the two latter are covered by the integuments and partly by superficial fascia ; the skin, thin and loose, is continued from the abdomen and scrotum around this organ, and extends some way beyond it in the form of a loose sheath, the prepuce, from the extremity of which it is inflected as far as the corona glandis, where it becomes very thin ; is thence continued over the glans to the orifice of the urethra, and is continuous with its lining membrane ; inferior to this opening it forms a triuigular fold, the fraMuim preputii ; the sides of the prepuce are 7. 2 340 DUBLIN DISSECTOR. connected together by a very loose reticular tissue, and this fold is expanded and obliterated when drawn back, or when the penis be- comes distended ; the inner side of the prepuce is like mucous mem- brane, and of more delicate texture than the external, and that portion of it which is continued over the glans is still more delicate than either. Beneath the skin, around the corona glandis, are a number of small sebaceous glands, glandulae odoriferae, or Tysoni ; the subcuta- neous tissue, both of the prepuce and penis, is very loose, is continu- ous with and similar to the dartos ; it is never the seat of adipose deposit, but is liable to serous infiltration ; the orifice of the prepuce is sometimes, particularly in young persons, so contracted that the skin cannot be retracted so as to allow the escape or protrusion of the glans; this is termed "phymosis," and, if in this condition the skin be forcibly drawn back over the base of the glans, it sometimes cannot be returned, but forms a tense constriction or strangulation round the latter ; this is termed " paraphymosis." The superficial fascia which covers the penis is continued from that of the abdomen, and extends around the penis as far as the corona glandis ; it is thick and strong posteriorly, where it is reflected from the linea alba on the penis, so as to form the superficial suspensory ligament of the latter ; it often con- tains some yellow, elastic tissue ; anteriorly it is loose and deh'cate. The crura, or corpora cavernosa penis, are two long, semi-cylin- drical bodies, composed of a strong, elastic, tendinous, and fibrous sub- stance, forming a sort of tube, filled with a soft cellular or erectile tissue, through which a large artery and many small tortuous veins, with free cellular inosculations, run from one end to the other. Each crus commences narrow in front of the tuber ischii, and adheres most inti- mately to the rami of the ischium and pubis, as far forwards as the symphysis ; anterior to this the two crura become inseparably united, and continue so as far as the corona glandis, forming the body of the penis ; here they end in one obtuse point, over which the glans penis, which is the expanded extremity of the corpus spongiosum urethras, is folded, but with which it has little or no vascular commu- nication : the crura are attached to the symphysis by the true suspen- sory ligament, which is very strong, of a triangular figure, yellow, and elastic ; it arises from the symphysis, and is inserted into each crus ; it consists of two lamina?, between which the dorsal vessels and nerves of the penis pass. The crura are separated from each other by an imperfect tendinous septum, composed of parallel fibres, with such intervals between them that the cavity of one crus communicates with and can be injected from that of the other ; this septum is named pec- tiniforme ; it is more perfect behind, but so deficient in front that the two crura may be regarded as one ; a number of fibrous cords (trabe- culce) also cross the interior of each ; these chiefly arise from the infe- rior surface, and thence radiate in different directions, and are inserted into the inside of each sheath ; both these and the septum must impart considerable strength to the organ, and limit its distension. The crura penis are somewhat conical, the apex of each being attached to the DUBLIN DISSECTOR. 341 ischiiun and pubis, the base supporting the glans ; they are round externally, flattened towards each other; a wide and deep groove exists between them inferiorly, which contains the urethra and its corpus spongiosum, and a more superficial one superiorly, in which the dorsal vessels and nerves of the penis run. The erection of the penis during life is caused by a greater quantity of blood than usually circulates through tin's organ being propelled by an increased action of the arteries into the small vessels of the corpora cavernosa penis, in- duced by a peculiar excitement of the nervous energy. Anatomists are not agreed as to the exact structure of the corpora cavernosa, or as to the proximate cause of their erection during life, or how the blood is circumstanced during that condition : some consider that the arteries pour their blood into the cells of the cellular tissue which surrounds them, so as to cause their distension, and that from these the blood is slowly and gradually absorbed by the veins ; others conceive that the arteries directly communicate with the veins, and that these latter vessels are tortuous and coiled to such a degree, their coils communi- cating by lateral openings, as to form the plexuses which serve to retard the course and delay the return of the blood, and so cause the distension and consequent erection of the whole organ. The contrac- tion of the dartos, and of the special muscles alluded to (at page 310), have been also supposed to contribute to this condition. The penis is supplied with blood from the terminal branches of the pudic artery ; opposite the ramus of the ischium arises the artery of the bulb, enclosed hi the triangular ligament ; it ramifies in the corpus spongiosum urethra as far as the glans ; the pudic then ends in the arterioe dor- salis penis and cavernosa ; the dorsal passes between the crura and the arch of the pubis, and between the laminae of the suspensory ligament; it then runs tortuously forwards near the median line, ends in seve- ral preputial branches, and in some deeper ones, which form a free circular inosculation around the corona glandis, and also communicate with branches in the glans and corpus spongiosum urethra?. The arteria cavernosa enters the crus near its origin, and proceeds tortu- ously through it, near the septum, giving off numerous small branches in its course ; these are entwined among the ramifications of the venous plexus, with which they communicate freely. Muller has described small vessels, " arteriae helecinae," as arising from this artery, and pro- jecting in tufts from each side of it into the venous cells : this opinion has not been confirmed by subsequent observation. The veins of the penis are large and numerous, and supplied with valves ; they are deep and superficial, the former accompany the branches and the trunk of the pudic artery, and join the internal iliac; the superficial com- mence in the prepuce, pass backwards, receiving branches from its sides and inferior surface, and form the two dorsal veins of the penis ; these pass beneath the arch of the pubis through fibrous canals con- nected to the sub-pubic ligament : these canals, like the sinuses of the dura mater, serve to keep the veins open and free from pressure ; they open into the prostatic and vesical plexuses. The nerves of the penis 342 DUBLIN DISSECTOR. are derived from the sympathetic and pudic branches of the spinal. Each of these strong fibrous cylinders is filled with an areolar or cel- lulo-vascular tissue, which is strengthened by thetrabeculae, and which itself is chiefly composed of an interlacement of veins : the cells com- municate freely with each other and with the veins. There appears to be in erectile tissue a gradation of structure between true veins and venous plexus ; thus at first we find the veins communicating, as it were, by lateral perforations ; these become more numerous, distinct vessels disappear, and a mass of communicating cells alone can be de- tected ; these cells appear formed of the prolonged lining membrane of the veins ; the interstices of this plexus are filled with a peculiar fibrous texture, of a reddish appearance, and bearing some resemblance to muscular tissue. The Urethra is a membranous canal, about nine inches long, ex- tending from the neck of the bladder to the extremity of the penis, formed of mucous membrane, covered by an elastic coat ; the former is continuous posteriorly with that of the bladder, anteriorly with the thin integument of the glans, and in different situations with the lining membrane of the ducts that open on its surface, namely, the prostatic, ejaculatory, Cowper's, and numerous lacunae. The elastic coat differs in strength in different situations, and is covered at first by the pros- tate gland ; this portion of the canal is called the prostatic portion of the urethra ; next by the compressors urethra? muscles, the triangular ligament, and a peculiar reddish, spongy, or erectile tissue, which con- tains several small blood-vessels, chiefly veins ; this is called the mem- branous portion ; it is separated from the subpubic ligament by some considerable veins, and from the rectum by the small triangular space, recto-bulbar, already described. The remainder of the canal is covered by a cellulo- vascular substance of a dark red or purple colour, named corpus spongiosum urethras, which commences in the bulb, and ends in the glans penis ; this portion is named the spongy portion. The course or direction of the urethra should be first attended to ; from the neck of the bladder it passes downwards and forwards ; having arrived opposite the symphysis pubis, it describes a very slight curve, concave upwards ; it then rises on a higher level than the bulb in front of the pubes, and enters the groove on the lower surface of the corpora ca- vernosa penis ; the remainder of its course depends on the state of the penis ; if the latter be collapsed, it forms a marked curve, concave downwards, but this can be changed into nearly a straight line by elongating the penis, and during the erection of the organ it becomes concave upwards, so that in this condition of the penis the whole canal forms but one curve in that direction, but in the collapsed state it forms two curves, somewhat like the letter S, with the posterior curve less sharp or acute. The first, or the prostatic portion, is within the pelvis, about an inch and quarter or an inch and a half in length ; in the erect position of the body its direction is downwards and forwards, is nearer to the upper than to the lower surface of the gland. The membranous portion is about half or three-quarters of an inch long, DUBLIN DISSECTOR. 343 and is the narrowest part of the canal except the anterior orifice ; it is di'scribc'd in general as being concave towards the pubes : it is, how- ever, but very slightly so ; it is nearly horizontal, about three quar- ters of an inch below the symphysis pubes ; it is surrounded by an elastic and erectile tissue, also by the deep lamina of the triangular ligament, and by the compressores urethras muscles. The spongy portion commences in the bulb in front of the triangular ligament, ex- tends to the extremity of the canal, and ends in the glans penis. The corpus spongiosum urethrte consists of a fine erectile tissue, through which an artery from each side (a branch from the internal pudic) extends ; these vessels send oif numerous branches, which pour their blood into the surrounding venous cells ; the bulb and the glans are expansions of this texture, the former on the inferior, the latter on the superior part and sides ; it is invested by a fine but strong and semi- transparent aponeurosis, very different from that which covers the corpora cavernosa ; it surrounds the urethra, biit is thicker inferiorly and laterally than superiorly. The bulb occupies the space between the crura penis, is opposite the arch of the pubis, in front of the rectum and below the level of the membranous portion of the urethra, and about an inch distant from the anus ; it terminates gradually in front, in the corpus spongiosum ; it is embraced by the acceleratores urinae muscles, and immediately covered and supported by the anterior or inferior lamina of the triangular ligament ; on each side, and rather posteriorly, are the glands of Cowper, between the lamina? of the triangular ligament, and immediately beneath the arteries of the bulb ; the bulb is very small in the child. The glans is the anterior conical enlargement of the penis, of the same structure as the bulb, only more dense ; its base projects beyond the crura superiorly and laterally, and forms the corona glandis, and is cut off obliquely, so that its upper surface is twice as long as its lower ; the prepuce is connected to it inferiorly by the fraenum. There is no direct communication between the corpus spon- giosum urethras and the corpora cavernosa penis ; the one can, there- fore, be distended with air or injection without the other, or both may be injected with different coloured fluids. In order to inject the crura penis, make a small opening in each crus near its attachment to the ischium, insert a pipe into one of these, and force warm water through it ; this will soon escape through the opening in the opposite crus, car- rying along with it the blood which was contained in the cells ; then secure with a ligature the opposite crus, and inject some coloured fluid. To prepare the corpus spongiosum urethra?, make a small opening in the substance of the bulb ; next open the dorsal vein of the penis ; in it secure a small pipe ; water injected through this will escape at the opening in the bulb ; when all the blood shall have been thus washed out, the latter opening may be secured, and some coloured fluid in- jected along the dorsal vein ; if, however, a fine injection be forced from the pudic, or from the internal iliac artery, it will occasionally succeed in distending the corpora cavernosa penis and the corpus spongiosum urethras at one and the same time. The student may 344 DUBLIN DISSECTOR. now detach the crura penis and the neck of the bladder from the pubes, and remove these organs, together with the urethra, from the subject ; continue an incision from the anterior part of the bladder through the upper part of the prostate gland, and of the urethra to its extremity ; the mucous lining of the urethra will be thus exposed ; the difference in the diameter and other peculiarities in different parts of it may now also be observed. 1st. The prostatic portion is some- what contracted at either extremity, and dilated in the centre, parti- cularly on the lower surface, and at either side of the middle line. These enlargements are called the prostatic sinuses ; they are sepa- rated from each other by a prominent fold of the lining membrane, extending from the uvula of the bladder, along the mesial line of the urethra, as far as the bulb. This fold is named verumontanum, or caput gallinaginis : in the centre of it is a very large lacuna (sinus pocularis), the orifice of which is directed forwards ; on either side of this pouch, and in general external to it, is the opening of the common ejaculatory duct, external to which, and in the prostatic sinus on each side, are the several small orifices of the ducts of the prostate gland. In the closed state of the urethra, the uvula and verumontanum are pressed against the upper part of the canal, and the whole ring is closed by the sphincter vesicae, but when the bladder contracts, this ring is expanded by the longitudinal fibres, and the verumontanum is depressed by some of the posterior fibres which are inserted beneath it ; the prostatic portion of the urethra is then considerably dilated. The opening of the sinus pocularis, usually not larger than a pin's head, is sometimes much more so, and may admit and obstruct a bougie or catheter in its course to the bladder 2nd. The membran- ous portion is shorter, and of a smaller calibre, than the prostatic ; it is cylindrical ; its anterior extremity is the narrowest portion of the canal. 3rd. The spongy portion of the urethra is much dilated at first, particularly inferiorly (sinus of the bulb) ; anterior to this the small ducts of the anti-prostatic glands open. The canal contracts a little beyond the bulb, and continues of nearly the same diameter until it arrives opposite the scrotum ; it is there slightly contracted for a short distance : about an inch posterior to the external orifice of the urethra the canal is dilated in the transverse direction ; this dilatation is called the fossa navicularis. Lastly, the orifice of the urethra is contracted into a narrow vertical slit. Several small lacunae open on the surface of the mucous membrane of the urethra, between the bulb and the anterior extremity ; they are said by some to be most nume- rous on the upper surface ; they are veiy variable in number and size ; the orifices of these, in a healthy condition of the membrane, are very small ; they are all directed forwards. If bristles be introduced into some of these ducts, they will be found in many cases to extend back- wards for near an inch in the submucous tissue : these lacunae secrete a thin mucous fluid, which is expelled by the urine in its passage along the urethra. In chronic diseases of the urethra, these ducts not unfre- quently become so much enlarged as to admit the end of a small DUBLIN DISSECTOR. 345 bougie, and so lead to the formation of a false passage : the largest lacunae are on the upper surface of the urethra ; one in particular, m-ar the fossa navicularis, is named the lacuna magna* This mem- brane is very extensible as well as dilatable, hence neither its length nor its diameter can be accurately stated ; it presents many longitudi- nal folds which admit of distension ; through it appear irregular lon- gitudinal fibres, probably elastic, but by some supposed to be muscu- lar : there is no regular arrangement of circular fibres. The epidermic character of this membrane is most distinct in its anterior portion. If the urethra be distended with spirit, and the crura penis and corpus spongiosum carefully dissected off, a beautiful preparation of this semi-transparent canal may be obtained. The testicle is the seat of many morbid appearances, both in its tunics and in its substance ; hydrocele is very common ; this is a dropsy in the serous cavity of the tunica vaginalis ; this latter mem- brane may be inflamed, and the adhesive process may obliterate its cavity. The tunica albuginea is sometimes the seat of a firm fungus, which protrudes through the other coverings to the surface. The tes- ticle and epididymis may be the seat of acute inflammation or orchi- ds, as in hernia humoralis, the effect of gonorrhoea, also of chronic inflammation, with indolent enlargement, or sarcocele. The testis is also the frequent seat of strumous inflammation and suppuration, of fungoid disease in which there is great enlargement, total change of structure, and conversion into cerebriform matter; of true scirrhus and cancer, of hydatid tumours, &c. : these glands are also sometimes atro- phied. The spermatic cord is sometimes the seat of encysted hydro- cele, of varicocele, particularly on the left side, as also of different tu- mours. The prostate gland is seldom found diseased, except in old men ; it is rarely inflamed ; an abscess, however, has been met with (unac- companied by any thickening) in its substance, arising from common inflammation. Scirrhus. The most common disease of the prostate gland is scirrhus ; the gland in its natural state is known to be about the size of a chesnut, but when affected with scirrhus, it is often enlarged to the size of the list. The common appearances observed in scirrhus in other parts of the body can be plainly seen in this * During the dissection of the pelvic viscera, perinasum, &c., the student should frequently practise the introduction of a catheter into the bladder, which is to be done in the following manner : the subject lying on its back with the legs drawn up, the penis should be held by placing the thumb and index-finger on each side of the corona glandis, by which means the orifice of the urethra will not be compressed , the penis is then to be drawn upwards, and the catheter, being previously oiled, is next to be introduced in a line with the linea alba into the urethra, directly downwards as far as the bulb ; the concavity of the instru- ment being towards the abdomen. The catheter having reached the bulb, its handle is to be depressed by bringing it forwards between the thighs, and in pro- portion as this is done the point is elevated, and the catheter glides into the blad- der ; in this latter part of the operation, the penis must be allowed to sink down, for if it be kept extended on the instrument the membranous part of the urethra will be drawn towards the pubes, by which means the introduction of the instru- ment will be rendered difficult. 346 DUBLIN DISSECTOR. gland ; when cut into, it appears to consist of a very solid, whitish, or brown substance, with membranous septa running through it in various directions. According to the degree of enlargement that takes place, the urine is passed from the bladder, or the catheter can be introduced to draw it off, with greater or less difficulty. Calculi have been found lodged in the ducts of the prostate gland ; they are usually small granules of a dark colour, and give it a mottled appear- ance when cut into. The vesicular seminales are seldom found diseased ; in case of scro- fulous disease of the testicle they have been found similarly affected and filled with cheesy fluid. The urethra is the frequent seat of in- flammation, which, when recent, produces suppuration without ulcera- tion, and, if long continued, causes a thickening of the submucous tissue, and thus renders the canal narrow and irregular, and so com- mences the foundation of stricture. Chancres have been found in it even so far back as the membranous portion, and at the orifice (gene- rally at the lower side) they are by no means uncommon ; a chancre in this situation being, according to M. Ricord, the real cause of the peculiar characters of gonorrhoea virulenta. The coverings of the penis are the frequent seat of ulceration, also those of the glans penis; the latter in old persons are very often attacked with warty, cancerous ulceration. 347 CHAPTER VII. DISSECTION OF THE FEMALE ORGANS OF GENERATION. THE generative organs in the female are more distinct from the urinary than in the male ; they may be divided into the external and internal : the external parts are the mons veneris, vulva, labia, cli- toris, nymphoe, vagina, and perinaeum. The mons veneris is an eminence placed on the upper and anterior part of the pubes ; it consists of a quantity of adipose substance be- neath the integuments, which in the adult are covered with hair. The vulva is the fissure, or common urino-sexual opening between the labia, extending from the mons veneris to within an inch of the anus. The anterior perinaum is the small space in front of the anus. The posterior perineeum is between the anus and the os coccygis. The labia externa or majora are the prominent folds of integument which extend from the mons veneris, one on each side of the vulva, thicker before than behind, and are united inferiorly hi a crescentic edge, called the commissure or fourchette, between which and the vagina is a small depression, called fossa navicularis; the labia are composed of fat and loose areolar tissue, with numerous sebaceous glands and hair bulbs, vessels, and nerves ; beneath the skin and mucous surface is a dartoid texture like that hi the scrotum ; they are liable to serous infiltration ; during parturition they are unfolded, and admit of the expansion of the vulva ; in the infant they are less developed than the following. The nymphce, or labia minora, descend one on each side of the vagina, from the prepuce of the clitoris, and are gradually lost about the centre of the vulva, on the sides of the vaginal opening ; they are folds of mucous membrane enclosing an erectile tissue, and are covered by a fine epithelium, and have numerous and distinct sebaceous follicles ; they are narrow behind, broad before, and bifurcate at the clitoris ; the lower division joins the glans clitoridis, the upper unites with that from the opposite in a hood-like fold, called the prepuce of the cli- toris ; variable as to size ; in some very small, in others very large and prominent, and in some nations hypertrophied and elongated to an extreme degree ; in the infant they are more developed in propor- tion than the labia, and usually project beyond them. The clitoris is in the median line, about half an inch below the superior angle or commissure of the labia : it is a small red projection immediately be- neath the sympliysis pubis and above the vagina; attached by two crura to the ranii of the ischii and pubes ; these unite and fonii the body of the clitoris, opposite the symphysis, to which it is connected 348 DUBLIN DISSECTOR. by a suspensory ligament ; it then passes forwards, like a ridge, be- tween the labia from their anterior commissure to its extremity, a little curved, convex upwards, concave downwards and backwards, and terminates in a round, red swelling or tubercle, which, from a resemblance to the glans penis, is named glans clitoridis, and is co- vered by the thin, loose fold of the integument or mucous membrane, called the prepuce, derived from the upper division of the nymphse. The crura clitoridis are composed internally of a spongy cellular tex- ture, not very unlike the corpora cavernosa, or the corpus spongiosum urethras in the male ; each crus is invested with an erector or com- pressor muscle analogous to the erector penis ; the urethra is received in the angle between the two crura, and, passing forwards beneath the body, ends behind the glans; the whole organ is erectile, being com- posed of spongy, erectile tissue enclosed in a fibrous sheath : like the nymphse, it is large in the infant ; in the adult its size is variable ; in some it is hypertrophied and elongated to the extent of one, and even two inches. About half an inch below and a little behind the clitoris, between the nymph, and immediately above the projecting edge of the vagi- nat opening, is the round orifice of the meatus urinarius ; this open- ing always appears closed, is surrounded by a projecting fold of mu- cous membrane, on the sides of which are orifices of small mucous glands analogous to Cowper's glands in the male, although probably the true analogues to these bodies are those two organs to which attention has been recently directed by M. Huguier, in a memoir read before the Academy of Medicine of Paris, and which are named the vulvo-vaginal glands. These were first described by G. Bartholinus, and have been noticed by the older writers, but no mention is made of them by modern authors. These glands are seated one at each side of and a little behind the vaginal orifice, in size and appearance like an apricot-stone covered with its epidermis; their excretory ducts, about half an inch long, open near the margin of the hymen at the base of the lateral and posterior caruncles, by which they are usually concealed : like the other parts of the generative apparatus, these be- come much developed at puberty ; they pour out a copious supply of clear, transparent mucus, which M. H. states can, under peculiar ex- citement, be ejected by the involuntary contraction of the surround- ing muscles. These glands and their ducts are very variable as to size, and, like the ch'toris and adjacent surface, possess peculiar sensi- bility ; their atrophy and hypertrophy bear a proportion to the condi- tion of the ovaries ; hence attention to their condition may assist in the diagnosis of disease : during pregnancy they are diminished, and in old age are atrophied ; they are occasionally absent ; in structure, and in situation, also in pouring forth their secretion on the common urino- sexual surface, they have some analogy to Cowper's, or the anti-pros- tatic glands. Immediately behind and a little below, but partly sur- rounding this opening, and from this descending on each side of the vagina, is an elevation of the latter by an erectile tissue, somewhat DUBLIN DISSECTOR. 349 analogous to the bulb or spongy portion in the male. The meatus is about an inch and a half in length, leads backwards and upwards in the upper wall of the vagina, to which it adheres almost inseparably, is slightly curved beneath the symphysis pubis, to which, as also ito the crura of the clitoris, it is attached by the triangular ligament and pelvic fascia, or rather by the anterior ligaments of the bladder ; be- tween its upper surface and the latter is a venous plexus ; this canal is composed of mucous membrane continued from the bladder, sur- rounded by an elastic, erectile, and muscular tissue ; this membrane is of a deep red colour, and presents longitudinal plicae, which account for its great dilatability ; longitudinal veins appear through it, and several lacuna? open upon it ; its elastic and erectile tissue retains it in a closed state ; the longitudinal fibres of the bladder can be traced through the cervix into the latter, and probably assist in the expansion of this canal when contracting the reservoir ; it perforates the triangular liga- ment of the urethra in the same manner as the membranous portion does in the male, to which division of the canal in the latter the female urethra is somewhat analogous. The compressores urethra? muscles, both vertical and transverse, are similarly arranged ; the vesical open- ing has no encircling prostate gland ; the anterior orifice is a little con- stricted by a surrounding fibrous band, which resists dilatation as in the male, but it has not the same form. The orifice of the vagina is directly below that of the urethra, is some- what oval, with aprojecting and rather corrugated margin ; in the virgin it is partially closed in front by a crescentic fold of membrane, termed the hymen; concave forwards, only leaving the anterior superior part of the orifice free ; very variable, however, it is sometimes circular, with an opening in the centre ; its loose edge is usually fringed ; it is some- times only rudimental, and on the other hand it is sometimes complete, and is then called imperforate hymen, a condition attended with danger, as it confines the menstrual secretion : it is a fold of mucous membrane enclosing some small vessels. After laceration the margin presents an irregular series of reddish, fringe-like processes, named the carunculce myrtiformes ; these are variable in number and size. The course and connexions of the vagina will be better seen when the pelvis shall have been divided for the purpose of examining the internal organs of generation. Dissect off the integuments and fascia from the perinaeum and labia, and the following muscles may be observed: the sphincter ani, levatores ani, coccygcei, and transversales perinai, are similar to the muscles of the same name in the male ; the middle fibres of the levatores ani are expanded on the sides of the vagina : the erec- tores clitoridis are analogous to the compressores penis ; and the sphincter vaginas, corresponds to the acceleratores urinae ; it extends from the clitoris superiorly around each side of the vagina to the cen- tral point of the perinaeum in front of the anus ; it may be described as double, each arising in common from this point, then, passing forwards as a flat band on the side of the vagina, is inserted by a tendinous expansion partly into the side of the clitoris and partly into its upper 350 DUBLIN DISSECTOR. surface and suspensory ligament, in conjunction with that from the other side ; it contracts the orifice of the vagina, which is the narrow- est part of the canal. Fig. 56.* Make the lateral section of the pelvis in the same manner as was directed in the dissection of the male pelvis (page 318). The perito- naeum may be first examined ; this will be seen to descend along the forepart of the rectum to within three or four inches of the anus ; is thence reflected forwards on the posterior part of the vagina, the supe- rior third of which it covers ; ascends on the posterior surface and sides of the uterus ; continues round the superior fundus of this organ to its anterior part, on which it descends as low as the cervix only, and has, therefore, no connexion to the vagina in front ; it is thence reflected to the bladder, and continued over this organ, as in the male, to the abdominal muscles; thus, in the female pelvis, the perito- naeum forms one cul de sac, which is deep, between the rectum and vagina, and another between the uterus and bladder, which is shal- low. From each side of the uterus a broad fold of peritonaeum is ex- * An antero-posterior section of the pelvis of a female, giving a lateral view of the viscera in situ. 1. The symphysis pubis. 2. The urinary bladder. 3. The urethra. 4. The uterus. 5. The vagina, 6. The labia pudendi. 7. The clito- ris. 8. The rectum. 9. The perteetomun reflected over the bladder, uterus, and rectum. DUBLIN DISSECTOR. 351 tended transversely towards each iliac fossa ; these are the broad liga- ments of the uterus ; enclosed superiorly between the laminae of each are the Fallopian tube in the centre, the round ligament of the uterus in front, and the ovarium with its ligament and vessels behind ; the ovary and round ligament raise the membrane into two lesser folds, which, with the Fallopian in the centre, have been named alee vesper- tilionis. Dissect off the peritonaeum from one side of the rectum and vagina, and the pelvic viscera Anil be more distinctly seen. The rectum takes the same course as in the male, only it is some- what more curved ; it lies behind the uterus and vagina, and united to the latter by a vascular plexus. The vagina surrounds the neck of the uterus, is prolonged a little way upon it, and forms a circular de- pression around it, deeper behind than before ; thence it descends obliquely downwards and forwards for about six or seven inches between the rectum, the bladder, and urethra, in the axis of the lower orifice of the pelvis, slightly concave before and convex behind, of a circular form, the anterior and posterior walls flattened and in contact ; the uterine end is the largest part, and often much dilated ; the inferior orifice or vulva is the smallest ; the anterior wall is shorter than the posterior ; very dilatable and veiy elastic, as is seen during and after parturition, closely connected anteriorly to the blad- der by reddish filamentous structure, like the dartos, arid inseparably to the urethra ; posteriorly it is attached to the peritoneum during its upper third ; the remainder adheres to the rectum by a loose, dartoid, and venous tissue ; the broad peritoneal folds, the reflections of the pelvic fascia, the levatores ani muscles, cellular tissue, and venous plexuses, are connected to its sides; inferiorly the constrictor sur- rounds it ; its anterior wall is thicker than the posterior, and the urethral portion is the most so; lined by a vascular mucous mem- brane, which is transversely rugose. These rugae are very distinct in the infant, they are not like the ordinary plicae of mucous membranes, to admit of distension, but firm ridges like those on the palate behind the anterior teeth ; they are seen on the upper and lower sur- faces, but chiefly on the former, and near the vulva. In the median line, on each surface, is a more prominent ridge or raphe, extending nearly the whole length ; these lines are called the columns of the vagina. This membrane is covered with a distinct epithelium of the squamous or cuticular kind ; it extends into the uterus, but there be- comes of a different nature ; it is furnished with numerous follicles and papillae, especially near the vulva ; the mucous membrane is covered by a dense fibrous tissue and by numerous vessels, particularly veins, which form a retiform plexus, or a spongy erectile body, which is covered by a fibrous and dartoid tissue above, and by the sphincter vagi- nae muscle below ; there is an increase of this spongy tissue at either side of the orifice, between it and the crura of the clitoris. Between the bladder and the vagina the ureter may be observed, connected to the upper and lateral part of the latter ; its course is longer and more curved in the female pelvis than in the male ; its vesical extremity 352 DUBLIN DISSECTOR. corresponds to the cervix uteri ; its entrance into the bladder is nearer the uvula than in the male, and the trigone is of greater transverse, but of less an tero -posterior extent. The peculiarities of the female bladder have been already noticed. The Uterus is situated in the pelvis, between the bladder and rec- tum, connected to both by peritonaeum, and fixed thereby in its situ- ation, as also by its broad and round ligaments, and by the vagina ; it enjoys, however, a certain degree of mobility ; it occupies the median line, but often inclines to one side, especially the left, and is more or less in contact with the convolutions of the small intestines. The uterus is of a flattened pyriform or triangular shape ; the larger end or fundus is superior and anterior ; the smaller end or cervix inferior and posterior ; the intermediate portion is named the body, and is separa- ted from the neck by a constricted line ; the vagina surrounds the cervix uteri, and ascends higher posteriorly than anteriorly ; about three inches long, one inch thick, and two broad at its fundus, this and the body equal two inches in length and the cervix one ; at the lower extremity of the cervix is a small transverse slit, the os uteri or os tinea; the long axis of the uterus leads obliquely back- wards and downwards in the same line as that of the upper orifice of the pelvis, and forms an angle, concave forwards, with the axis of the vagina, which leads obliquely forwards and downwards in the line of that of the lower orifice. The anterior surface is flattened, and co- vered by the peritonaeum in its upper three- fourths ; the lower fourth is connected to the inferior surface of the bladder by cellular tissue: the posterior surface is more convex, and is entirely covered by perito- naeum : the sides are slightly concave, and give attachment to the broad, round, and ovarian ligaments, and to the Fallopian tubes. The broad ligaments are the two peritonaeal folds which extend to the iliac fossae, and form with this organ a transverse septum in the pelvis, between the bladder and rectum. The round ligament arises on each side anterior and inferior to the Fallopian tube, ascends obliquely out- wards in the anterior fold of the broad ligament, passes through the internal ring into the inguinal or spermatic canal, accompanied by a close sheath of peritonaeum (canal of Nuck), escapes through the ex- ternal ring, and is lost in the cellular tissue of the mons and labium externum ; is composed of muscular and fibrous tissue derived from the uterus, together with small, tortuous arteries, a venous plexus and filaments from the spermatic nervous plexus ; these ligaments retain the uterus in the median line, and, when it becomes enlarged, support it anteriorly, and draw it towards the abdominal muscles ; the veins in these cords are not unfrequently in a varicose state ; the arteries maintain a communication between those of the uterus and the groin. The ovarian ligament is a round, fibro-muscular cord, from an inch and a half to two inches long, arising from the upper arid lateral angle of the uterus, below and behind the Fallopian tube, and inserted into the inner end of the ovary. The Fallopian tubes extend from the upper angles of the uterus towards each side of the pelvis. The supe- DUBLIN DISSECTOR. 353 rior end or fundus is convex, and directed upwards and forwards ; it is behind the bladder, and below the level of the pubes. The lower end, or cervix, presents the os nteri or tinc3 at its termination, looks backwards and downwards, is embraced by and projects into the vagina. The os is small and circular, and the lips or borders smooth, hi the virgin, but in those who have borne children it becomes larger and more transverse, and the edges slightly fissured or wrinkled ; it presents two lips, one is anterior or superior, and thicker than the other, which is posterior or inferior, and longer. The parietes of the uterus are nearly a quarter of an inch thick ; its cavity, therefore, is very small, the surfaces nearly in contact, mucus only interposed ; the area in the body and fundus is somewhat triangular, the base above. The cervical portion is cylindrical and flattened, communi- cates with the vagina by the os uteri or tincae, or ostium externum, above which the canal through the cervix is narrowed, and leads into the body of the uterus by a very constricted opening, the ostium in- ternum. The triangular cavity in the uterus then commences ; the apex is in this opening, the base in the fundus, each angle of which is depressed into a funnel-shaped recess, in the bottom of each of which is the very minute orifice of the Fallopian tube. The uterus, being the organ for the gestation of the embryo during the long period be- tween its conception and the completion of its maturity, and also the principal agent in its final expulsion from the body of the parent, pos- sesses very peculiar organization, and is endowed with peculiar and interesting powers. It is composed of three different tissues or tunics, a serous, a fibrous or fibro-inuscular, and a mucous ; it is furnished with nerves and vessels, which are small in the quiescent state of the organ, but which become wonderfully developed during uterine gesta- tion ; it possesses very little of the areolar, and none of the adipose tissue, except the thin, connecting lamina between its peritonaeal and moBcalar tunics. The first or serous coat invests the fundus and body, all the posterior, and the three upper fourths of the anterior surface ; on each side of the anterior cul de sac, between the uterus and bladder, it forms a semi-lunar fold, named vesico-uterine ligaments, and in like manner its reflection from the vagina to the rectum pre- sents, on either side of the posterior cul de sac, a semi-lunar fold, named recto-uterine ligaments ; it adheres closely to the fundus and surfaces, but loosely to the sides, and, as the organ enlarges, the late- ral duplicatures or broad ligaments unfold and expand, and thus ma- terially contribute to a corresponding extension of the serous invest- ment. Tin's coat answers the same uses as on other hollow viscera ; when the womb is distended, it supports and strengthens its other tissues, it insulates it from surrounding parts, and mutually facilitates its motions and those of the adjacent organs. The mucous membrane is in general pale, though sometimes very dark ; it is smooth, and fur- nished with an epithelium, which is columnar and ciliated. In the cervix it presents longitudinal median lines or columns, from which 2A 354 DUBLIN DISSECTOK. pass off, at nearly right angles, smaller transverse rugae, like branches of a tree. This appearance, named arbor vitae uterina, is more per- fect in the virgin state : in this region of the uterus in particular are many mucous follicles, the closure and distension of which give rise to a vesi- cular, and sometimes even a morbid appearance (ovula of Naboth) ; the membrane is smoother and more vascular in the body than in the cervix ; this difference has been well observed in those who have died during the menstrual period ; under ordinary circumstances this mem- brane is very fine and delicate, and so difficult of demonstration that some have even (but erroneously) denied its existence ; it is continuous inferiorly with that of the vagina, and superiorly it extends through the Fallopian tubes and their fimbriated extremities, where it is con- tinuous with the peritonaeum on each side, thus presenting the single example of continuity between a mucous and serous membrane. The middle or muscular coat is very thick and firm, and resists the knife like cartilage ; composed of strong, greyish fibres, closely inter - Avoven and traversed by numerous vessels. The true nature of this structure could not be known if our observations were confined to the unimpregnated human uterus ; examination, however, of this organ, when pregnant, aided by the microscope, corroborated by chemical analysis, and elucidated by comparative anatomy, have revealed its true character to be muscular tissue ; this, in the quiescent state of the organ, is condensed, and, as it were, atrophied, but, when impreg- nated, the parietes become wonderfully vascular, the fibres softened and unravelled, the sensibility and nervous energy proportionably exalted, and the muscular structure is then developed in an eminent degree ; the muscular fasciculi become evident, and are expanded into extended laminae, whose fibres interlace in the same manner as those of the involuntary system, or of organic life in general ; like the fibres of the latter, also, they want the transverse striae. Around the cervix they are in circular laminae, some fibres interlacing or crossing others; on the body and fundus the fasciculi are large, and flat bands dis- posed in a superficial and deep lamina; the superficial are longitudinal or vertical on the front and back part, and oblique on the sides and fundus, and at the angles of the latter are continued on the Fallopian tubes and on the round and ovarian ligaments ; the deep layer con- sists of two series of conical fibres, the apices around the Fallopian tubes, the bases intermingling on the body of the uterus. This tunic of the uterus is truly interesting from the very curious changes it can undergo ; thus through the greater portion, and often through the entire period of life, it remains inactive, and condensed into a thick, close, and almost solid, whitish, homogeneous mass, without a single feature in common with contractile tissue ; with this contrast its plainly muscular appearance in the gravid uterus, when its fibres admit of a passive extension and elongation to an almost unlimited extent, while at the same time they present all the characters of highly developed muscle, except the manifestation of the contractile DUBLIN DISSECTOR. 355 power, which it refrains from exercising with anv vigour until the period of parturition, at which hour it displays this power with extra- onlinary energy and with wonderful intensity and force. During pregnancy the vascular system also of the uterine parietes is equally developed ; the uterine urtrries, which are derived from the internal iliac, and the sprnnntic from the aorta, become enlarged, elongated, and tortuous. The uterine veins are still more remarkable ; they form large channels (uterine sinuses), like the larger vena; cavas hepatica;, through the uterine Avails, and appear formed only of the lining membrane which adheres to the surrounding fibrous tissue ; these veins form plt'xnscs at each side of the uterus, and open into the internal iliac, the renal, and the cava. The nerve* of the uterus proceed from the hypogastric plexus, which consists of filaments from the sacral and Iinnliar and pelvic ganglions of the sympathetic ; these nerves accom- pany the uterine arteries ; others are derived from the renal plexus, and accompany the spermatic arteries; all these nerves arc small in the unimpregnated organ, and difficult to follow, but, like the muscular and vascular tissues, they also become enlarged during pregnancy into a great system of nerves, whereby not only are its functions regulated, but a sympathy is also maintained with the entire system. These nerves have beendescribed by Hunter and Tiedemann, and more recently and ably by Lee (Phil. Trans., 1842). The latter has described seve- ral nervous ganglia and plexuses in and about this organ, viz., the hypogastric ganglia, which are near the ureters on each side of the cervix, and which receive nerves from the hypogastric plexus, and Mipply the rectum, bladder, vagina, and uterus, with filaments which form minor ganglions, each named from their situation ; the branches of the uterus ascend, and, meeting some from the spermatic plexus, form a large ganglion (spermatic), which supplies the fundus ; the lilameiits from these several ganglia form a sort of nervous net- work over the entire organ. (See Nervous System). The more minute examination of the muscular, vascular, nervous, and mucous tissue in this organ, and of the changes which each undergoes in the several stages of pregnancy, are of great interest ; this study belongs, however, to that of the anatomy of the gravid uterus, which does not properly come within the limits of the present work. In the embryo, and previous to the third month, the uterus is found developed as bih'd or bicornate, a condition which is permanent in many animals ; about the fourth month the two cornna have united to form a single cavity: the two funnel-like depressions in the superior angles, in which arc the internal orilices of the Fallopian tubes, correspond with this ori- ginal conformation. An imperfect septum may coexist with this bifid form, of which the two median lines, or raphes, in the vagina, may )>e regarded as rudiments. In the fietns, at birth, the uterus is situated in the abdomen, and is very small; the cervix is longer in proportion than the body or fundus: as the pelvis is developed it gradually subsides into it, but undergoes little change or increase until 2 A 2 356 DUBLIN DISSECTOR. near puberty, when it rapidly attains its full dimensions and proper form ; in old age it becomes atrophied, and is often inclined to one side, or turned backwards towards the rectum ; a well-marked constriction then separates the neck and body, the latter becomes thin and softened, the former very dense, and the lips of the os are nearly effaced. The Fallopian tubes or oviducts are two in number, one on each side, from four to five inches in length ; they extend from the upper angles of the uterus to near the sides of the superior opening of the pelvis, at first straight upwards and outwards, then tortuously downwards and backwards, and a little inwards, loose and floating, supported by the broad ligaments, in the upper border of which they are enclosed behind the round and before and above the ovary and its ligament ; its uterine half is small, but the external portion is nearly the size of a goose-quill ; its calibre is very contracted throughout, and is like that of the vas deferens, to which this duct is also analogous in its firm, cord-like feel ; it opens internally into the upper angle of the womb by a minute foramen, almost capillary (ostium uterinum) ; externally by a much larger opening into the peritonzeal cavity (ostium abdomi- nale) ; this extremity, named corpus fimbriatum, is expanded in a trumpet form ; is soft, and irregularly fringed, or, as it were, lace- rated ; from this appearance, and from the manner in which it is sup- posed to seize the ovary during conception, the term morsus diaboli has been applied to it. The fringes surround the opening by one or two rows or borders ; it partly overhangs the ovary, and is connected to it either by one of the fringes, or by a fibrous band, which serves to conduct the tube to that body. This conformation can be well seen when the tube is removed and floated in water ; like the uterus, these are composed of three tunics : the external or serous, derived from the broad ligaments, is loose and easily detached ; the middle or fibrous, or fibro-muscular, consists of two planes of fibres, external or longitu- dinal, and internal or circular ; they are continuous with those of the uterus, and most probably of the same muscular character : the inter- nal or mucous coat is continuous with that of the uterus internally, and with the peritonaeum externally ; it is soft and reddish, and thrown into longitudinal plicae designed to admit of dilatation ; its epithelium is columnar and ciliated ; the external fimbrise are chiefly composed of the mucous and serous tissues ; the former is soft and vas- cular, the latter very thin ; the fibrous coat is wanting, or nearly so ; this extremity of the tube is dilatable, and much larger than the ute- rine portion. The Fallopian ducts are essential to reproduction ; they transmit the fecundating principle of the male to the ovary, which they embrace, and then conduct the fecundated ovum into the uterus. The ovaria, or female testes, are two small oval bodies, white or pale red, flattened before and behind, one at each side, enclosed in the posterior fold of the ligament, behind the Fallopian tube, connected to the uterus by the broad ligament and by a round, fibrous cord, its proper liga- ment, which is about two inches long, is enclosed between the laminae IM'IU.IN DISSI-X'TOR. 357 of the broad ligament, and is attached to the inner end of the ovary ami to the upper part of the side of the uterus, a little below its supe- rior angle : to its outer extremity, also one of the fringed processes of tlu' morsus diaboli, or a fibrous band, is attached ; it is free before, be- hind, and above : it is composed of a cellulo-vascular tissue enclosed in three tunics, a serous, a fibrous, and a vascular ; the serous invests the greater portion of it, and adheres most intimately to the fibrous coat, which is white, strong, and sclerotic ; the vascular not only covers it, but is continued into it internally, and assists in forming its areolar tissue. In the cells of this vascular structure, or stroma, a number of small vesicles are developed (Graafian vesicles) ; these are very varia- ble in number and size ; from six to ten or twelve, fully formed, are usually observed, but the microscope reveals numerous minute ovisacs throughout the parenchyma. This structure is most distinct if ex- amined shortly after parturition, the ovary being then swollen, soft, spongy, and vascular, and the vesicles enlarged. The Graafian vesi- cles are small, transparent cysts, varying in size from a pin's head to a small pea, containing a transparent, yellowish fluid, and adhering to the stroma ; each has two coats, an external or vascular, and an in- ternal (the ovi-capsule), lined with epithelium ; in each vesicle there is usually only one ovum at first in its centre, but as it is matured it approaches the inner surface of the internal coat, and becomes sur- rounded by a granular covering. An ovum is a spherical body, of uniform size, about j^g of an inch in diameter, with a thick but trans- parent coat, which surrounds the yolk ; within the latter is the ger- minal vesicle of Purkinjie, and within this again is the germinal spot of Wagner. (For further information on this subject, and on the changes that follow impregnation, see Muller's Physiol., transl. by Baly ; also Carpenter's Human Phys., p. 684). On one or both ovaries we commonly observe an appearance known under the name of corpora lutea. A corpus luteum is considered to be the remains of a vesicle ruptured hi consequence of impregnation ; it is usually a small, yellowish, brownish mass, of a spongy tissue, traversed by white bands, and containing a small cavity which had been occupied by the ovum ; it is lined by a puckered membrane, the remains of the ovisac ; if recent, the opening from this sac, through the capsule of the ovary, whereby the ovum escaped, is distinct ; when this is closed a small cicatrix exists in its situation. As the ovaries contain the ova, they are essential to reproduction. In the foetus they are large in proportion, and, like the testes, occupy the lumbar regions, and gradually descend into the pelvis. During pregnancy they are carried up into the abdomen along with the uterus, to the sides of which they are closely applied : shortly after parturition they are situated in the iliac fossae, and are not unfrequently retained there by adhesions during the rest of life. The mammary glands have been already examined (page 74). The female organs of generation are the seat of many morbid 358 DUBLIN DISSECTOU. changes. Not to notice the various ulcerations to which the external parts are liable, we occasionally find here also polypi, adipose, and sarcomatous tumours in the lahia, enlargement of the clitoris, &c. The uterus may be found inflamed (matritis) ; this most frequently occurs soon after parturition ; the adjacent peritonaeum is then also generally affected : the uterus itself exhibits the same appearances as other inflamed parts ; the inflammation is found to creep along the Fallopian tubes and ovaries. It often advances to suppuration, and pus is generally found in the large veins of the womb. In puerperal peritonitis, it has been remarked, that the extravasated fluid and coa- gulable lymph are found in a greater proportion to the degree of in- flammation, and the lymph softer and more coloured, than in common peritonitis. Polypi are very frequently found in the uterus; they may grow at any period of life, but they are rarely met with in the young. By a polypus is meant a diseased mass, which adheres to the cavity of the uterus by a sort of a neck or narrower portion. Polypus is of two different kinds ; the most common is hard, and consists of a substance divided by thick membranous septa. This sort of polypus varies much in its size, some not being larger than a walnut, and others exceeding in bulk a child's head. Another sort of polypus forms in the uterus, which consists of an irregular bloody substance, with tattered processes hanging from it ; when cut into, it appears to be a spongy mass, containing large cells. The most common part to which polypi adhere is the fundus uteri, and sometimes they are found attached to the os tineas. Hard, fibrous tumours also not unfrequently exist in the parietes of the uterus. One of the most frequent affections of this organ is a granulated state of the os tincso, giving rise to leucor- rhcea. The os, and the parts about it, are covered with minute red eleva- tions, like the surface of a raspberry, and the interstices are covered with a fluid resembling pus, but which is really serum. The uterus is also the seat of cancer, which usually commences near the os tinea?. It is likewise often subject to partial displacement, viz., prolapsus, inversio, and retroversio. The investing membrane, or the substance of the ovary, are very rarely found inflamed, except when they are included in general peri- tonitis. When the inflammation proceeds from the uterus, or from the csecum (perityphlitis), as occasionally happens, it sometimes goes on to the formation of pus in the ovary. The most common disease in the ovary is dropsy ; the whole substance of the ovarium is sometimes converted into a capsule containing fluid, the natural structure has disappeared, and it is found converted into cells, communicating with one another by considerable openings, and very much enlarged. The ovaria are sometimes converted into a series of cysts, which have no communication with each other : these cysts have been confounded with hydatids, to which they bear some resemblance ; they are, how- ever, very different ; they have much firmer and less pulpy coats than hydatids ; they contain a different kind of fluid, and they are diffe- 1UT.UX DI88BCTOB. oo'J rcntly connected among themselves. Ilydatids either lie unconnected, or diii 1 largo one encloses a number of small ones; while ovarian eyste ad lu-re to each other by broad surfaces, and do not enclose each other. The ovaria are sometimes found converted into cysts, holding large masses of fat, hair, ami some teeth ; these substances appear to be ge- nerated by the internal membrane of the cyst; the hairs are most of them loose in the fatty substance, but many of them adhere to the inside of the capsule ; the teeth, which are not always perfect, are sometimes attaehed to the cyst, and at others to an irregular mass of bone. 360 DUBLIN DISSECTOR. Fig. 57.* * The muscles of the anterior aspect of the trunk and extremities ; on the right side the superficial layer is seen, and on the left side the deeper layer. 1. 1. Supinator radii longus. 2. 2. Extensor carpi radialis longus. 3. Pronator radii teres. 4. Flexor carpi radialis. 5. Palmaris longus. 6. Flexor digitorum sublimis. 7. Flexor carpi ulnaris. 8. Portion of flexor digitorum sublimis. 9. Pronator quadratus. 10. Abductor pollicis. 11. Portion of obliquus externus abdominis. 12. Portion of obliquus internus. 13. Rectus abdominis. 14. In- ferior border of external oblique forming the crural arch. 15. Tensor vaginae l.ri'.I.IX DISSECTOR. 361 CHAPTER VIII. DISSECTION OF THE INFERIOR EXTREMITIES. EACH inferior extremity is connected to the trunk by the strong ligaments of the hip joint, and by several muscles which pass from the pelvis to the thigh and leg. This dissection may be performed while the pelvis remains attached to the spine, or the former may be sepa- rated from the lumbar vertebrae, and divided into two. The muscles of the lower extremity are classed into those of the pelvis or hip joint, thigh, leg, and foot ; those of the thigh are ar- ranged into posterior, anterior, external, and internal. As several of the muscles of the pelvis or hip cannot be seen until some of the inter- nal muscles of the thigh have been removed, it is inconvenient to com- mence the dissection of the limb with that of the former. We divide the whole series into two groups ; the first includes the anterior, exter- nal, and internal muscles of the thigh ; the second the muscles of the hip and of the back of the thigh : first examine the coverings of the limb from the pelvis to the knee, especially the fascia lata. SECTION I. DISSECTION OF THE l^USCLES OF THE THIGH. PLACE the extended limb on the back part, raise the integuments from the anterior and lateral parts of the thigh, and from the upper part of the leg ; several cutaneous nerves, veins, and lymphatic vessels are met with in this dissection ; the nerves are branches of the lumbar plexus and of the anterior crural nerve ; they pierce the fascia lata near Poupart's ligament, and descend chiefly along the anterior and outer side of the thigh. The cutaneous veins are branches of the in- ternal saphena vein. This vessel will be found, when dissecting the leg and foot, to commence at the inner side of the latter, and to ascend femoris. 16. Rectus femoris. 17. Sartorius. 18. 18. Vastus externus. 19. 19. Femoral portion of the psoas magnus and iliacus interims muscles. 20. 20. Pecrtnaeus muscle. 21. 21. Adductor longus. 22. Gracilis. 23. Part of the ad- ductor magnus. 24. 24. Vastus internus. 25. Crurseus. 26. The patella. 27. 27. Tibialis anticus. 28. 28. Extensor digitorum communis. 29. 29. Extensor pol- licis proprius. 30. Peronaei muscles. 31. Internal portion of gastrocnemius, 32. Solaris. 362 DUBLIN DISSECTOK. along the internal part of the leg and knee to the inner and forepart of the thigh, along which it continues its course to the groin ; about an inch and a half or two inches below Poupart's ligament it pierces the fascia lata, and joins the femoral vein. In this course it receives several cutaneous branches, and, in general, just before it ends in the femoral, it is joined by one or two large veins from the outer and fore- part of the thigh, and by some smaller branches from the abdominal parietes ; some cutaneous branches from the anterior crural and lum- bar nerves accompany this vein in its course along the thigh. Beneath the integuments the thigh is invested by the superficial fascia, which is prolonged around it from the parietes of the abdomen. In the groin this fascia is thick and laminated, and closely connected to the fascia lata, particularly to its cribriform portion ; but inferiorly and poste- riorly it is thin and loose, as ordinary sub -cutaneous cellular tissue. This fascia may be easily detached from the fascia lata, except in the groin ; in attempting to raise it in this region we expose the superficial inguinal glands, some of which lie between its laminae ; they are eight or ten in number ; five or six of them are placed parallel to Poupart's ligament, some above, others below it ; two or three are situated lower down in the groin than these, near the termination of the saphena vein. These last glands lie on the fascia lata ; they are larger than the former, and are parallel to the saphena vein. Through these con- globate glands the superficial absorbents of the lower extremities pass, also those from the external parts of generation. Beneath the fascia lata, close to, and generally internal to the femoral vessels, are the deep-seated inguinal glands ; small, only three or four in number ; they transmit the deep-seated absorbents of the limb. The integuments and superficial fascia having been removed, the fascia lata, or crural, or femoral aponeurosis, may be next examined. This aponeurosis surrounds the thigh ; it is very strong and tendinous externally, but so thin and weak internally that without caution it may be removed along with the integuments 5 it is attached superiorly and externally to the crest of the ilium ; posteriorly*to the sacrum and coccyx : on the glutaeus maximus it is weak and thin, but at the anterior border of this muscle it becomes very strong, receiving an addition of fibres both from the tendon of that muscle and from the tensor vagina? femoris ; anteriorly it is attached to Poupart's ligament, and internally to the rami of the ischium and pubis ; as it extends down the thigh it con- fines the different muscles in their situation, so as to preserve the figure of the limb ; several processes also pass inwards to form septa and sheaths for some muscles, and to bind others in their place : to many of these processes the muscles adhere, so that when in action they serve to make the fascia more tense and resisting ; this is espe- cially the case with the glutams maximus and the tensor vagina; : these processes also serve to increase the surface of origin or attach- ment of several muscles. Along the posterior part of the thigh it is connected to the whole length of the linea aspera, also to the insertion of the glutasus maximus, and to the origin of the short head of the DUUI.IX DISSECTOR. 330 biceps ; infcriorly it adheres to the eomlyles of the femur, surrounds the knee-joint, and receives an addition of fibres from the difl'crent ten- dons in this region ; a bursa separates it from the patella ; below the knee it is continued over the heads of the tibia and libula into the fascia of the leg. Numerous foramina are observable in the fascia lata, particularly at the upper and anterior part of the thigh ; they transmit cutaneous nerves and vessels : the most remarkable of these holes is that for the saphena vein ; it is situated on the anterior and inner aspect of the thigh, about an inch and a half or two inches below Pou- part's ligament, and may be most distinctly seen by dividing the vein below, and raising it towards the abdomen. This opening is semi- lunar, the concavity directed upwards ; from its apparently sharp edge the fascia is reflected backwards, and is lost on the sheath of the fe- moral vessels. That part of the fascia which is internal to this open- ing is named the pubic portion of the fascia lata ; it covers the pecti- nunis muscle, adheres to the spine and linea innominata of the pubis, extends behind the femoral vessels, and divides into two lamina? ; one is continuous with the fascia iliaca, in front of the psoas and iliac ten- don ; the other passes deeper and behind this tendon to join the ilio- femoral capsule ; that part of the fascia lata external to the saphenic opening is called the iliac portion; it covers the sartorius, tensor vaginae, rectus, and iliacus internus muscles, and is continued ob- liquely in front of the femoral vessels, in the form of a crescentic or falciform process, the concavity of which is directed downwards and inwards ; the convexity is towards the ilium, and attached to Poupart'.s ligament ; the lower cornu of this crescentic process is continuous with the outer cornu of the saphenic opening, and the upper cornu extends in front of the femoral vessels to their inner side, and is inserted along with the third insertion of Poupart's ligament, or Gimbernaut's liga- ment, into the linea iunominata, or ileo pectinaja. Between the mar- gin of the falciform process and the pubic part of the fascia lata is a thin membrane, perforated by numerous vessels ; this is termed the cribriform fascia ; it is connected on either side to the iliac and pubic portions of the fascia lata, and may be regarded either as a thin lamina of the fascia lata connecting these two lateral portions, or as a deep layer of the superficial fascia ; it extends from the saphena vein to I'oupart's ligament, in front of the sheath of the femoral vessels ; it adheres to the anterior part of this sheath, or to the fascia transver- >alis; when this cribriform fascia is removed the falciform process is made more distinct. (See Description of Crural Hernia, page 214.) The fascia lata, in some situations, particularly along the outer side of the limb, is seen to consist of two lamina- of fibres; the external take a circular, the internal a longitudinal direction ; these two lami- na* are very distinctly separated at the upper and outer part of the thigh by the insertion of the tensor vagina? femoris ; the deep layer, which in this situation is very strong, is attached to the capsular liga - ment of the hip joint, and to the external head of the rectus muscle ; of its intermuscular septa two are very strong, external and internal ; 364 DUBLIN DISSECTOR. the external extends from the great trochanter to the external con- dyle, attached to the linea aspera ; the vastus externus adheres to it in front, the short head of the biceps behind ; it is pierced above by the external circumflex, and below by the external articular vessels. The internal intermuscular septum arises from the anterior intertrochan- eric line, and is inserted into the inner condyle, adheres to the linea aspera between the vastus internus and the adductor tendons. These two great septa separate the muscles on the front from those on the inner and back part of the thigh ; between the two latter regions again a weaker septum is interposed, so that there are three principal mus- cular compartments, one for the postei'ior, another for the internal, and a third for the anterior muscles ; and the two latter compart- ments are subdivided into sheaths for the separate muscles, as will be seen in the course of their dissection. Raise the fascia lata from the anterior and lateral parts of the thigh ; several muscles will come into view, the femoral vessels also in the groin will be par- tially exposed ; they are still somewhat concealed by a quantity of adipose substance, by a few deep-seated lymphatic glands, and by their anterior sheath or the fascia transversalis ; when the former are removed, and the latter opened, we always find the vein internal to the artery, and about an inch and a half from the spine of the pubis : im- mediately external to the vein is the artery resting on the psoas, and about a quarter of an inch external to the artery is the anterior and crural nerve, imbedded between the psoas and iliacus, and covered by the fascia iliaca ; it does not, therefore, lie in the sheath of the vessels : internal to the vein, between it and the inner wall of the sheath, is the femoral ring. Clean the several muscles which now partially appear on the forepart of the thigh : external to the vessels the sartorius and tensor vaginae are first seen ; internal to the vessels are the pectinseus, gracilis, and the three adductors ; and immediately covering the ante- rior and lateral parts of the femur are the rectus, cruraeus, vastus in- ternus, and externus. SECTION II. MUSCLES ON THE FOREPART AND SIDES OF THE THIGH. THESE are eleven in number. 1. TENSOR VAGINAE FEMORIS, at the upper and outer part of the thigh, narrow above, broad and thin below, arises tendinous and fleshy from the external part of the anterior superior spinous pi*ocess and crest of the ilium ; it forms a fleshy belly, which descends ob- liquely backwards, and is inserted, broad and thin, into a duplicature of the fascia lata on the outside of the thigh, about three or four inches below the great trochanter. Use, to make tense the fascia, and com- press the vastus externus ; to rotate the thigh inwards ; also to assist Dl'BLIN DISSECTOR. 365 ill flexing and abducting it. The origin of this muscle is between the sartorius and glutens medius ; between these mus- cles it descends, covered by the fascia lata : its insertion is anterior to that of the glutieus maximus muscle. 2. SARTORIUS, or the tailor's muscle, is the longest muscle in the body, thin and flat like a riband, broader in the mid- dle than at the extremities, situated ob- liquely along the anterior and inner side of the thigh, arises by short, tendinous fibres from the anterior superior spine of the ilium, and from the notch below that process, it soon becomes broad and fleshy, extends obliquely across the thigh to its inner side, and, descending perpendicu- larly to the knee, passes behind the con- dyle of the femur ; it then turns forwards and outwards towards the inner side of the upper end of the tibia, into which it is inserted below the tubercle by a long, flat tendon, the anterior edge of which is attached to the fascia lata covering the knee-joint, and the posterior edge sends off an aponeurosis to the fascia of the leg. Use, to flex the leg upon the thigh, also the latter on the pelvis ; to adduct the thigh and leg obliquely, so as to cross the lower extremities, or to place one foot on the opposite knee; when the thigh and leg are extended, it assists in raising and advancing forwards the whole limb, also in turning the knee outwards ; in stand- ing it also supports the pelvis, and pre- vents it bending backwards on the thigh ; it may then also flex the body, and ro- tate it to the opposite side. This muscle through its whole extent is covered only by the fascia lata and the integuments ; Fiy. * The muscles on the forepart and sides of the thigh. I. The internal iliac fossa. 2. The crest of the ilium. 3. The anterior-superior spine of the ilium. 4. The anterior portion of the glu tarns medius. ~>. The tensor vagina} femoris muscle, cut off just below its insertion into the fascia lata. (i. The sartorius. 7. The rectus t'cinoris. SI-:CTOR. tendons together, the vein lying superficial : from the tendon of the gracilis an aponeurosis is sent off to the fascia of the leg. 8. PECTINM-:US. tlat, triangular, broad above, situated at the supe- rior, anterior, and internal part of the thigh ; arises fleshy from the linea innominata and the concave surface below it on the horizontal rainus of the pubis, between the spine of that bone and the ilio-pecti- na-al eminence ; it forms a flat, fleshy belly, which descends obliquely outwards and backwards, and, becoming narrower and a little twisted, is inserted by a flat tendon into the rough ridge which leads from the lesser trochanter to the linea aspera. t/se, to adduct and flex the thigh, also, to rotate it outwards ; it may also serve to strengthen the capsular ligament of the hip joint internally, and in adduction of the limb to draw the capsule inwards from between the neck of the femur and the acetabulum. It lies between the psoas magnus and the adductor longus ; the latter overlaps it, covered superiorly by the fascia lata, and inferiorly by the femoral vessels, the fascia interven- ing ; it covers the obturator nerve and vessels, the external obturator muscle, and the adductor brevis ; it also adheres to the capsular liga- ment of the hip joint. TRICEPS ADDUCTOR FEMORIS consists of three portions, which pass in distinct laminae from the pelvis to the thigh. 9. ADDUCTOR LONGUS, flat and triangular, base below, is situated at the upper and internal part of the thigh, superficial to the other adductors and to the pectinasus ; it arises by a short, small, but strong tendon from the anterior surface of the pubis, between its spine and the symphysis ; this ends in a broad, fleshy belly, which descends ob- liquely backwards and outwards, and is inserted by a broad, thin tendon into the middle third of the linea aspera, between the adductor magnus and the vast us interims, to both of which it is closely united. The origin of this muscle lies between the pectinaaus and the gracilis, and above the adductor brevis : its insertion is behind the vastus inter- ims, and in front of the profunda artery, and adductor magnus ; is co- vered by the integuments and fascia superiorly, and by the sartorius and femoral vessels inferiorly ; and there forms the posterior wall of that remarkable fibrous tube which encloses the femoral vein and artery in the middle of the thigh : it lies anterior to the two following muscles : its tendon is perforated by vessels. 10. ADDUCTOR BREVIS, thick and fleshy, short, flat, and triangu- lar, is situated posterior to the adductor longus and pectinseus, and internal to the psoas ; (trisc* flat and tendinous from the anterior infe- rior surface of the pubis, betAveen the gracilis muscle, the symphysis pubis, and the thyroid hole ; it soon ends in a fleshy belly, which passes outwards, backwards, and a little downwards, inserted by ten- dinous slips into the superior third of the internal root of the linea aspcra, extending for about three inches below the lesser trochanter; its origin is external to the gracilis, and internal to the obturator ex tennis, and concealed by the adductor longus and pectinaeus ; as it descends it is covered by these muscles, except a small portion near 2 it 370 DUBLIN DISSECTOK. its insertion, which appears between them ; this portion is posterior to the femoral and profunda vessels ; its insertion is anterior to that of the adductor magnus ; in its tendon one or two large openings fre- quently exist for the passage of some of the perforating arteries. 11. ADDUCTOR MAGNUS, the longest and largest of the adductors, very thick internally, triangular, the base attached to the femur, the apex to the pelvis ; composed of thick and separate fasciculi like the glutaeus maximus ; arises chiefly fleshy from the anterior surface of the descending ramus of the pubis, external to the gracilis, also from the ramus of the ischium, and tendinous from the external border of the tuberosity of the latter ; the fibres pass outwards with different de- grees of obliquity ; those which arise from the pubis ascend obliquely outwards, those from the ramus of the ischium pass outwards and downwards, and those from the tuber ischii more directly down- wards; inserted fleshy into the rough ridge which leads from the great trochanter to the linea aspera, tendinous and fleshy into the linea aspera, and by a long round tendon into the internal condyle of the femur, immediately above the inner tendon of the gastroc- nemius. This muscle forms a septum between the inner and back part of the thigh ; its superior edge has a twisted appearance, is nearly parallel to the quadratus femoris ; several branches of the in- ternal circumflex vessels pass between these, and in rotation of the leg inwards the lesser trochanter also projects between them ; the mid- dle portion, which is inserted into the linea aspera, is internal to the insertion of the glutaeus maximus, and to the origin of the short head of the biceps. This part of the muscle is perforated by several branches of the perforating arteries ; at the lower part of the linea aspera it ap- pears to separate into two portions, one of which is inserted into this line, between the vastus interims and the short head of the biceps ; the other is continued into the long tendon, which is inserted into the inner condyle ; the femoral vessels pass between these into the popli- taeal space. The adductor magnus is covered internally by the gra- cilis, and anteriorly by the long and short adductors, pectinaeus, part of the sartorius, and the femoral vessels ; posterior to it are the sciatic nerve and the hamstring muscles ; the tendinous insertion of the lower part of this muscle is intimately connected to the vastus internus. About the inferior fourth of the thigh there is a large oblique opening, bounded by these two muscles and by the adductor longus, through which the femoral vessels pass into the popliteal space. This muscle, particularly its origin, should also be examined on its posterior aspect, where it is covered by the three hamstrings, the sciatic nerve, and a large quantity of cellular and adipose tissue ; in this aspect its divi- sion into two is more distinct ; the superior or external portion passes more transversely outwards, consists of distinct fasciculi, the aponeu- rotic insertions of which are united with the other adductors, forming arched and incompressible openings for the passage of the femoral vessels, and for three or four perforating branches of the profunda artery ; the internal portion principally arises from the tuber ischii, descends DUBLIN DISSECTOR. 371 nearly vertical, and ends in the tendon which is inserted into the inner condyle. Use, the three adductors, in addition to addticting the limb, can rotate it outwards ; they also serve to steady and support the pelvis on the thigh ; the long and short adductors can also flex the thigh on the pelvis, and the adductor magnus can extend it when it has been flexed. In dissecting the preceding muscles we observe the following vessels and nerves : The Femoral Artery passes from under Poupart's ligament, about midway between the symphysis pubis and the spine of the ilium, de- scends obliquely inwards and backwards, and about the lower part of the middle third of the thigh perforates the adductor magnus, enters the popliteal space, and then receives the name of popliteal artery. In the upper third of the thigh, or in the inguinal region, it is covered only by the skin, superficial fascia, some lymphatic glands, and the fascia lata ; in the middle third of the thigh it receives the additional cover- ing of the sartorius, and beneath this of a very strong tendinous apo- neurosis, which passes from the tendons of the adductor longus and magnus over the artery and vein, and joins the tendon of the vastus internus. In this part of the thigh it is thus enclosed in a perfect ten- dinous sheath, consisting anteriorly of the aponeurosis just mentioned, posteriorly and internally of the tendons of the adductor longus and magnus, and externally of the vastus internus : at the lower end of this sheath it passes into the ham, through a large oval opening, which is bounded superiorly by the adductor longus and magnus, exter- nally by the vastus internus, internally by the adductor magnus, and inferiorly by the united tendons of the adductor magnus and vastus in tennis. The femoral artery in this course first passes over a few fibres of the psoas, next over the pectinaeus and adductor brevis, the adductor longus, and a small portion of the magnus : immediately below Poupart's ligament gives off, 1st, some cutaneous branches ; 2nd, small arteries to the inguinal glands ; 3rd, about two inches below Poupart's ligament, a very large branch, the profunda ; 4th, several muscular branches to the sartorius and vastus internus ; and 5th, just before it enters the ham, the anastomotica magna, which is distributed to the muscles and integuments at the inner side of the knee. The profunda is the largest branch of the femoral ; it descends behind that vessel and to its inner side, and gives several branches to the muscles of the thigh, namely, the external and internal circumflex, and the three or four perforating arteries. (See Anatomy of the Vas- cular System.) The femoral vein takes the same course as the artery; in the groin it always lies to its internal or pubic side, but as it de- scends it becomes posterior to it. In dissecting the muscles on the forepart of the thigh, numerous branches of the anterior crural nerve are met with. This nerve in the groin is separated into several branches ; many of these become cutaneous, others pass to the mus- cles on the forepart of the thigh, and two or three accompany the fe- moral artery ; one of these, the nervus saphemis, enters its tendinous sheath, and, descending along the forepart of the artery, as far as the DUBLIN DISSECTOR. Fig. 59.* * The muscles on the posterior aspect of the thigh and leg; part of the superfi- cial layer has been removed on the left side. 1. The glutseus maximus. 2. '2. DUBLIN DISSECTOR. 373 opening in the tendon of the triceps, then leaves that vessel, descends botwwn the tendons of the sartorius and gracilis muscles to the inner side of the knee, becomes cutaneous, and, attaching itself to the sa- phrna vein, accompanies this vessel along the inner side of the leg to the internal ankle. (See Anatomy of the Nervous System.) SECTION III. DISSECTION OF THE POSTERIOR PART OF THE THIGH. PLACE the detached extremity on its forepart, with a block beneath the hip joint, so as to flex the latter slightly, and thus extend the muscles in this region. Raise the integuments from the posterior sur- face of the limb, from the crest of the ilium to the calf of the leg. The cutaneous nerves which are met with in this dissection are branches from the lumbar nerves, from the sacral plexus, and from the sciatic nerve. The cutaneous veins pass in different directions, some turn round the inner side of the limb to the saphena vein, others penetrate between the muscles, and join the deep veins which accompany the muscular or the perforating arteries, and others descend to the popli- teal space, and join the popliteal or the lesser saphena vein. The fascia lata over the glutaeus maximus is weak, but anterior to that muscle, that is, covering the glutseus medius, it is very strong, and adheres to the surface of this muscle, and to the crest of the ilium above it. On the posterior part of the thigh the fascia is not so dense as on the outer or the anterior part ; inferiorly, over the popliteal re- gion, or the ham, it is much stronger than above ; from the thigh it is continued over the muscles of the leg, in which situation it may be examined afterwards : the fascia and integuments being removed, the muscles should be cleanly dissected ; these may be divided into the muscles of the hip and of the thigh. The glutasus medius. 3. Part of the pyriformis muscle. 4. The superior gemel- lus. 5. Portion of the obturator internus. 6. The inferior gemellus. 7. 7. The vastus extemus, covered on the right side by the fascia lata. 8. 8. The long head of the biceps flexor cruris. 9. Its short head. 10. 10. The semi-tendinosus. 11. The semi-membranosus. 12. The gracilis. 13. Part of the adductor magnus. 14. The popliteal region. 15. The gastrocnemius muscle. 16. 16. Theplantaris. 17. 17. The solfeus. 18. The popliteus. 19. 19. Thetendo Achillis. 20. 20. The os calcis. 21. 21. The tendons of the peroneus longus and brevis passing behind the external malleolus. 374 DUBLIN DISSECTOR. SECTION IV. DISSECTION OF THE MUSCLES OF THE HIP. THESE are nine in number, viz., the three glutaei, the pyriformis, the gemini, the two obturator, and the quadratus femoris. Fig. 60. * 1. GLUT^EUS MAXIMUS covers the greater part of the pelvis, also the upper part of the thigh ; it is somewhat square, one edge being the origin and attached to the sacrum, the opposite edge or the insertion to the femur, and to the fascia lata, the other edges are directed one upwards and forwards, the other downwards and backwards. The inferior edge is thick and round, and covered by a great quantity of fat ; this forms the fold of the nates. It is difficult to clean the sur- * The muscles of the hip. 1. The posterior surface of the sacrum covered by a flense aponeurosis. 2. The os coccygis. 3. 3. The crest of the ilium. 4. The external surface of the great trochanter. 5. The linea aspera of the femur. 6. The glutaaus maximus muscle. 7. A portion of the glntseus medius covered by the fascia luta. 8. The same muscle on the opposite side exposed. 9. The vastus externus muscle covered by the fascia lata. 10. The great sacro-sciatic ligament. 11. The tuberosity of the ischium. 12. The pyriformis muscle. 13. The supe- rior gemcllus. 14. A portion of the obturator interims. 15. The inferior gemel- lus. 16. The tendon of the obturator extemus. 17. The quadratus femoris. 18. The tendon of the glutfeus maximus thrown down to shew its insertion. 19. The biceps femoris muscle. 20. The semi-tendinosus. 21. The semi-membra- nosus, 22. The gracilis muscle. 37") face of the gluta-us niaximus, its fasciculi arc so coarse and rough ; this may IK- facilitated by dissecting parallel to the fibres, that is, in a line drawn from the sacrum towards the great trochanter. This mus- cle arises by fleshy and short aponeurotic fibres from the posterior fifth of the crest of the ilium, from the rough surface between the crest and the superior semicircular ridge on this bone, from the posterior sacro-iliac ligaments and lumbar fascia, from the tubercles on the pos- terior surface of the sacrum, the side of the coccyx, and from the great sciatic ligaments, which last it covers ; the fibres are collected into distinct fasciculi, which descend obliquely outwards and forwards, nearly parallel to each other, converging a little towards the thigh : the lower fibres are the longest, the}' all form a strong and dense mass, particularly below, and end in a flat and thick tendon, whose external surface is rough and coarse, but the internal smooth, and lined by a bursa which separates it from and allows it to glide over the great trochanter ; this tendon is inserted into a rough ridge, which leads from the trochanter to the linea aspera, also into the upper third of that line, and by a tendinous expansion into the fascia lata, covering the vastus externus muscle. Use, to extend the thigh, also to abduct and rotate it outwards, to support and extend the pelvis and the trunk on the lower extremity, also to make tense the fascia lumborum and the fascia lata- The glutaeus niaximus is covered by the integuments, by a considerable depth of fat, and by a thin fascia ; the fat is most abundant towards the lower part, where it forms an elastic cushion in the sitting posture ; this structure is continuous with a very loose eel- lulo-adipose tissue, which covers the tuber ischii, and which allows the muscle to glide over that projection. As the fascia approaches the upper edge of the muscle, it becomes more strong and adherent, and is thence extended over the anterior part of the gluttons medius, to which it adheres very closely, and is then inserted into the crest and anterior spine of the ilium. The glutams niaximus covers the tuber ischii and all the muscles on the posterior part of the pelvis, except the anterior portion of the glutaeus medius, which is covered by the fascia just now mentioned ; its insertion into the linea aspera is above the short head of the biceps, and between the vastus externus and adductor magnus ; a very large bursa lines its tendon, and is expanded over the trochanter and a portion of the vastus externus ; it is very thin, it usually contains much synovial fluid, and it is frequently in- tersected by tendinous bands : a smaller bursa is often situated below it, between the tendons of the glutseus niaximus and vastus externus. Divide this muscle by a perpendicular incision, and separate the edges. Several muscles, vessels, &c., may be noticed, having the fol- lowing relation to each other : commencing above, we see the glutaeus medius muscle, beneath this the pyriformis, and between these the glutaeal vessels and the superior glutaeal nerve ; below the pyrifonn muscle the great sciatic and some smaller nerves, also the sciatic and pudic vessels, all escaping from the pelvis by the lower part of the sciatic notch. Next in order arc the gemini muscles surrounding the 376 DUBLIN DISSECTOR. tendon of the obturator internus ; below these is the quadratus femoris, parallel to the superior fibres of the adductor magnus ; the great sci- atic ligament, the tuber ischii, and the superior attachment of the hamstring muscles, are all seen in this dissection, also several small arte- ries and veins, and a considerable quantity of loose, watery, cellular tissue, which surrounds the sciatic nerve in its course through the de- pression between the trochanter and tuber ischii. 2. GLUTJEUS MEDIUS, triangular, flat, thinner than the last de- scribed muscle, is exposed by dividing the glutaeus maximus and dis- secting off the strong fascia, which extends from its anterior edge to the crest of the ilium ; arises by fleshy and aponeurotic fibres from the deep surface of this fascia, from the three anterior fourths of the outer edge of the crest of the ilium, from the superior semicircular line or ridge which leads from the anterior spinous process of the ilium to the upper part of the sciatic notch, and from the surface of the ilium, above and below that ridge. The fibres descend in different directions ; the middle perpendicularly, the anterior, which are very short, and the posterior, which are long, obliquely ; they all converge into a strong and broad tendon, which is inserted into the upper and outer part of the great trochanter, and is attached anteriorly to the tendon of the glutaeus minimus. Use, to abduct the thigh ; its posterior fibres can extend and rotate it outwards, its anterior fibres can flex and rotate it inwards ; it also serves to maintain the pelvis in equilibrio on the femur, as when standing on one leg. This muscle is covered in part by the glutaeus maximus ; the anterior and larger portion is covered only by the integuments, the fascia lata, and its tensor ; it lies on the glutaeus minimus, its posterior edge is parallel to the pyriform muscle, and separated from it by the gutaeal vessels and nerves ; the anterior edge is nearly parallel to and behind the tensor vaginas muscle, is united to it above, but separated from it below by a quantity of fat, and by several branches of the external circumflex vessels and nerves. 3. GLUTAEUS MINIMUS is exposed by detaching from its origin the glutaeus medius ; small, semicircular, more tendinous than the last, it arises from the inferior semicircular ridge on the dorsum of the ilium, and from the rough surface between it and the edge of the acetabulum ; the fibres converge as they descend, and end in a strong, round, twisted tendon, which is inserted into the upper and anterior part of the great trochanter, first passing over a small bursa. t/se, similar to the last ; it also strengthens the ilio-femoral articulation, and as it adheres to the capsular ligament it can draw this out of the joint in abduction of the thigh. This muscle is covered by the glutaeus me- dius, and a little overlapped by the tendon of the pyriformis ; it covers the capsular ligament and the external tendon of the rectus. The six glutaei muscles are most powerful agents in maintaining the body in the erect posture, by resisting the tendency which its weight has to bend it forwards, hence these muscles are developed in man to a degree superior to any other animal. 4. PYRIFORMIS is of a flattened, triangular form, the base at the I > I I5LIN DISSECTOR. 6 I 7 sacrum within the pelvis, the apex at the trochanter ; situated partly within the pelvis, partly behind the hip joint, nearly parallel to the posterior border of the glutaeus minimus ; it arises within the pelvis by three tendinous and fleshy fasciculi, from the anterior or concave surface of the second, third, and fourth divisions of the sacrum ; it also receives a few fibres from the anterior surface of the great sciatic ligament, and from the upper and back part of the ilium ; the fibres form a thick, fleshy belly, which, passing through the great sciatic notch, descends obliquely outwards and a little forwards, and is in - serted by a round tendon into the upper part of the digital fossa, at the root of the great trochanter above the tendons of the gemini and obturator muscles, to which it is connected. Use, to abduct the thigh, to extend and rotate it outwards ; it can also act on the capsular liga- ment in the same manner as the glutaeus minimus. Within the pelvis this muscle lies on the sacrum, and is covered by the hypogastric ves- sels, the sciatic plexus of nerves, and the rectum ; the sciatic nerve often perforates it near its lower margin ; on the dorsum of the pelvis it is covered by the glutaeus maximus, and is parallel to but not co- vered by the glutaeus medius ; it adheres to the capsular ligament, and is superior to the gemini, from which it is separated by the sci- atic nerves and vessels ; it divides the sciatic notch into two parts, through the superior, pass the glutaeal vessels and nerves, through the inferior the sciatic and pudic vessels, the sciatic nerve, and several smaller branches of the sacral plexus of nerves. To expose the fol- lowing five small rotator muscles of the hip joint, draw to either side the great sciatic nerve, and remove the surrounding loose cellular tissue. 5, 6. GEMELLI, two small muscles inferior to the last, behind the ilio- femoral articulation, and between the ischium and the trochanter ; the SUPERIOR small, sometimes absent, arises narrow and fleshy from the spine of the ischium : the fibres pass outwards above the tendon of the obturator internus, and are inserted with it into the upper part of the digital fossa of the great trochanter. INFERIOR arises also fleshy, from the upper part of the tuber ischii, and from the great sciatic li- gament, the fibres run parallel to the former, and are also inserted into the digital fossa. Use, to rotate the thigh outwards, also to abduct it, to strengthen the capsular ligament, and to confine the obturator tendon in its situation. These muscles are concealed by the glutaeus maximus and the sciatic nerve ; are placed between the pyriformis and quadratus femoris muscles : they form a sort of sheath around the tendon of the obturator internus, and adhere to its edges, and appear as portions of this muscle added to it as it escapes from the pelvis : the inferior is the larger of the two ; the superior is inserted between the pyriformis and the obturator internus, and the inferior between the tendons of the obturator internus and externus : they both adhere to the capsular ligament. 7. OBTURATOR INTERNUS is situated partly within the pelvis and partly behind the ilio-femoral articulation ; somewhat triangular, the 378 DUBLIN DISSECTOR. base within the pelvis, the apex at the great trochanter, arises by aponeurotic and fleshy fibres within the pelvis from the superior or pelvic surface of the obturator or thyroid ligament, and from all the circumference of the foramen of that name, except at the upper part, where the obturator nerve and vessels pass through ; beneath these a ligamentous arch is extended, and from this some fibres of this muscle proceed ; it also arises from the pubis internally, from the ischium inferiorly, and from the thin but strong fascia of the same name which covers it, and separates it from the levator ani muscle ; the fibres descend obliquely outwards and backwards, converging towards the lesser sciatic notch, which is between the spine and the tuberosity of the ischium ; the fibres here end in a flat tendon, which, turning outwards, winds round the cartilaginous pully-like surface which the ischium presents ; a loose bursa, and one, in general con- taining a quantity of synovia, is interposed between it and the bone ; the tendon now runs outwards on the dorsum of the pelvis, between the gemini, and is inserted into the digital fossa of the great tro- chanter. Use, to abduct and rotate the thigh outwards ; it may also act on the capsular ligament. This muscle within the pelvis is covered by the peritonaeum, the pelvic fascia, levator ani muscle, and by a strong aponeurosis, the obturator fascia, which serves to give origin to some fibres both of this and of the levator ani muscles, between which it is interposed ; it is the external layer of the pelvic fascia, adheres superiorly to the ilium and pubis, and inserted iiiferiorly into the great sciatic ligament, into the tnberosity and ramus of the ischium, also into the ramus of the pubis, and is continuous with the triangular ligament of the urethra ; it is closely connected to this muscle ; inferiorly the internal pudic nerve and vessels partly inter- vene, and are partly enclosed in the tissue itself (pages 308, 319). As the obturator tendon is passing through the sciatic notch, its deep surface is divided into four or five distinct tendons, which are lined by the synovial membrane, and connected to each other like so many plaits or folds ; the pudic vessels lie external to the tendon in this situation ; the continuation of the tendon to its insertion has the same relations as the gemini muscles. 8. QUADRATUS FEMORIS, arises by fleshy and aponeurotic fibres from the external surface of the tuber ischii, anterior to the tendon of the semi-membranosus ; the fibres pass transversly outwards, and are inserted tendinous and fleshy into the inferior and posterior part of the great trochanter, and into the posterior inter-trochanteric line. Use, to adduct and rotate the thigh outwards : this muscle is covered by the gluta3us maximus and sciatic nerve ; its origin is also concealed by the hamstrings ; it is parallel to and between the gemini and the adductor magnus ; its lower border is overlapped by the latter ; it covers the obturator externus, the lesser trochanter, and the insertion of the psoas and iliacus. Divide this muscle, and a little dissection will expose the following, particularly if the gracilis, adductor, and pectinaeus muscles have been previously removed. IH'IiMN DISSECTOR. H/9 9. OBTURATOR EXTI.KMS, situated at the superior, posterior, and internal part of the thigh, somewhat triangular or pyramidal, the base towards the pubis, the apex at the trochanter; arises fleshy from the inferior surface of the thyroid or obturator ligament, and from the surrounding surface of the pubis and ischium, the fibres descend obliquely outwards and backwards behind the neck of the femur, in a sort of notch or grooved pulley between the tuber ischii and the edge of the aoetabulum ; here they end in a strong tendon, which ascends a little behind the neck of the femur, then runs directly outwards along the inferior gemellus, and, adhering to the capsular ligament, is inserted into the lower part of the digital fossa. Use, to adduct the thigh, and to rotate it outwards ; it also supports and strengthens the inferior and posterior part of the ilio-femoral articulation, particularly in abduction of the thigh. This muscle is placed in a very deep situation, being covered anteriorly and inferiority, by the adductor brevis and peetinonis, also by the obturator nerve and vessels, inter- nally by the adductor muscles, externally by the joint, and posteriorly by the quadratus femoris and glutaeus maximus. The several small muscles just described, in addition to their indi- vidual actions, effect the common purpose of strengthening the ilio- femoral articulation. The capsular ligament of this joint is covered anteriorly by the rectus, psoas, and iliacus ; internally by the pecti- naeus and obturator externus ; externally by the tendon of the rectus, the glutanis minimus and medius; posteriorly by the pyriform, gemini, obturator tendons, quadratus femoris, and glutseus maximus ; and in- feriorlv by the tendon of the obturator externus. Many of these muscles, like the small capsular muscles of the shoulder joint, guard against dislocation in the different motions of the limb, and also serve to protect the capsular ligament by drawing it out of the angle which is formed between the acetabulum and the neck of the femur in the rotatory motions of the thigh ; in the extended state of the limb, they chiefly act as rotators outwards, but in its flexed state they are ab- ductors ; when standing on one leg, which thus becomes fixed, they can rotate the pelvis and the trunk to the opposite side. In dissecting the foregoing muscles, several vessels and nerves must have been remarked ; the former are derived from the hypogas- tric or internal iliac vessels ; the latter from the sacral plexus of nerves ; the arteries are the glutaeal, sciatic, and pudic. The glutceal artery escapes through the upper part of the sciatic notch, above the pyriform muscle, and immediately divides into several branches; these are distributed to the three gluta>i muscles. The sciatic artery passes out of the pelvis through the lower part of the great sciatic notch, below the pyriformis; its principal branches descend between the tuber ischii and the great trochanter, and are lost in the surround- ing muscles. The pudic artery escapes from the pelvis along with the last described vessel; it soon, however, re-enters the cavity through the lesser sciatic notch, and pursues its course forwards and inwards towards the periiueum and pubis, lying at first on the internal surface 380 DUBLIN DISSECTOR. of the obturator internus, and afterwards on the rami of the ischium and pubis; its branches are distributed to the external organs of gene- ration, and to the muscles in the perineum. (See Anatomy of the Vascular System). Each of these arteries has its corresponding vein, which takes a similar course, and terminates in the internal iliac vein. The nerves which are found in this situation are the superior and inferior glutaeal, the posterior cutaneous, the pudic, the great and lesser sciatic ; these are all branches of the sacral plexus, except the superior glutceal nerve, which is a branch of the lumbo-sacral, it accompanies the glutaeal artery, and is distributed principally to the glutaeus medius and minimus muscles. The inferior glutceal nerve escapes below the pyriform muscle, and is distributed principally to the glutaeus maximus. The inferior or lesser sciatic nerve accompa- nies the last through the sciatic notch, descends obliquely inwards round the tuber ischii, and is distributed to the surrounding muscles and integuments. The posterior cutaneous nerve also passes through the lower part of the great sciatic notch, descends beneath the glutaeus maximus, and then, becoming cutaneous, divides into several long branches, which may be traced along the posterior surface of the thigh, even to the leg, where in general they will be found to communicate with the posterior cutaneous nerves of that region. The pudic nerves take the same course as the pudic artery, and terminate in corres- ponding branches. The great sciatic or posterior crural nerve is the largest nerve in the body ; it passes out of the pelvis below, but often through the pyriform muscle; descends behind the hip joint in the fossa between the trochanter and tuber ischii, covered by the glutaeus maximus, and passing over the gemini, obturator, and quadratus muscles ; its course along the back of the thigh, and its branches, shall be considered after the dissection of the following muscles. SECTION V. DISSECTION OF THE MUSCLES ON THE BACK PART OF THE THIGH. THE fascia hi this situation has been already noticed ; the muscles are only three in number, and are commonly called hamstrings ; the semi-tendinosus and semi-membranosus form the inner, the biceps the outer hamstring. BICEPS FLEXOR CRURIS consists of a long and short head : the LONG HEAD arises from the outer and back part of the tuber ischii and rather above it, in common with the semi-tendinosus ; this de- scends obliquely outwards, and soon ends in a thick fleshy belly; about the inferior third of the thigh it joins, at an acute angle, the SHORT HEAD, which arises fleshy from the linea aspera, between the DISSKCTOR. 381 vastus externus and the adductors, commencing below the insertion of the gluta-us maximus, and continuing to within two inches of the external condyle ; here the muscle ends in a strong tendon, which descends at first behind the knee, then turns forwards and outwards towards the head of the fibula, into which it is inserted ; the tendon is here divided in general by the external lateral ligament into two fasciculi, the superficial of which, in addition to its attachment to the head of the fibula, is also inserted into the fascia of the leg ; and the deep fasciculus, which is also inserted into the fibula, sends some fibres to the head of the tibia. Use, to flex the knee-joint, also, by its long head, to extend the thigh and rotate the whole limb outwards ; the long head can also fix the pelvis, prevent it and the trunk from bending forwards on the head of the femur, raise the body when bent, and maintain the erect posture. The superior fifth of this muscle is concealed by the glutanis maximus, the remainder is covered by the integuments and fascia, and descends between the vastus ex- tern us and semi-tendinosus, forming the outer hamstring ; the long head passes over the semi-membranosus, the sciatic nerve, and the triceps muscles ; it also conceals the short head : inferiorly the biceps passes over the external articular vessels and the external head of the gastrocnemius muscle. 2. SEMI-TEXDIXOSUS, large, flat, and fleshy above, round and ten- dinous below, arises by fleshy fibres from the tuberosity of the ischium in common with the long head of the biceps, also from the inner or anterior edge of the tendon of the latter for about three inches ; it de- scends obliquely inwards, and about four inches above the knee it ends in a long round tendon, which, passing behind the head of the tibia, is then reflected forwards between the tendon of the semi-mem- branosus and the internal head of the gastrocnemius, and is inserted into the anterior angle of the tibia below its tubercle, inferior and posterior to the tendons of the gracilis and sartorius, to which it is connected : from the convex edge of the tendon an aponeurosis is given off, which joins the fascia of the leg. Use, to flex the knee and rotate the leg inwards, to extend the thigh, to support the pelvis, and prevent the trunk bending forwards This muscle is covered supe- riorly by the glutanis maximus; the rest of its course is superficial ; a transverse aponeurotic line usually intersects it about its centre. 3. SEMI-MEMBRAXOSUS, beneath the semi-tendinosus, flat and aponeurotic superiorly, thick and fleshy in the middle, round and ten- dinous below ; arises by a flat tendon from the upper and outer part of the tuber ischii ; this descends obliquely inwards, ends in a fleshy belly, which retains the muscular structure lower down than either of the former muscles ; a little above the knee it ends in a round tendon, which passes behind the internal condyle, and divides into three pro- cesses, one of which passes outwards, another downwards, and a third forwards ; the first is a broad aponeurosis, which ascends obliquely outwards, beneath the heads of the gastrocnemius muscle. over the back part of the knee-joint, and is inserted into the external 382 DUBLIN DISSECTOR. condyle of the femur ; this aponeurosis has been termed the posterior ligament of the knee-joint, or the ligament of Winslow ; the second is a strong and broad fascia, which descends over the popliteus muscle, and is inserted into the posterior part of the heads of the tibia and fibula, and is also continuous with the deep fascia of the leg ; the third process appears the continuation of the tendon, turns forwards beneath the internal lateral ligament, round the head of the tibia, into which it is inserted. Use, to extend the thigh on the pelvis, and to support the latter on the thigh, to flex the knee and to rotate the leg inwards ; it also strengthens the back part of the knee, and can draw the synovial membrane out of the angle of the joint. This muscle, at its origin, lies external to the other hamstrings ; covered at first by the semi-tendinosus, biceps, and glutasus maximus, inferiorly it is superficial ; above it passes over the quadratus femoris and adductor magnus muscles ; below it overlaps the popliteal vessels, and the in- ternal head of the gastrocnemius, from which last it is separated by a bursa : the sciatic nerve is on its outer, the gracilis on its inner side. The arteries which are met with in the dissection of these muscles are branches of the sciatic, circumflex, perforating, and articular ; the numerous ramifications of these vessels are distributed to the ham- string and adductor muscles, and are accompanied by their corres- ponding veins : the principal nerve in this situation is the great sciatic ; from the back part of the hip joint, this large nerve descends along the back of the thigh to the iipper part of the popliteal space, where it divides into the peronreal and posterior tibial nerves; in this course it is covered at first by the glutaeus maximus, afterwards by the biceps and semi-tendinosus, and inferiorly by the integuments and fascia ; having passed over the quadratus femoris and the other small muscles at the back of the hip joint, it next lies on the adductor magnus, and inferiorly on a quantity of adipose substance. The sciatic nerve gives off several cutaneous and muscular filaments, in addition to its two terminating branches, the peronjeal and the poste- rior tibial ; the peronatal nerve takes the course of the biceps tendon towards the head of the fibula, where it divides into several branches which are distributed to the integuments and muscles on the outer and forepart of the leg, as will be described in the dissection of that region. The posterior tibial nerve accompanies the popliteal vessels through the space of that name, which space the student should next examine. The popliteal space is situated behind the knee-joint, extending upwards for about one-fourth of the thigh, and downwards for about one-sixth of the leg ; it is somewhat oval, is bounded internally by the inner hamstring, and the internal head of the gastrocnemius ; ex- ternally by the biceps, external head of the gastrocnemius, and plan- taris ; it is covered by the integuments and by a strong fascia, which, derived from the fascia lata, is strengthened by adhering to the con- dyles of the femur, and to the adjoining tendons ; this fascia serves to approximate the sides of this region, and thus to give to it a consider- DUBLIN DISSECTOK. 383 able depth. The popliteal space is bounded before by the flat surface of the femur, by the back part of the joint covered by the ligament of Winslow, by the head of the tibia, and by the popliteus muscle and its fascia. In this region are contained the terminating branches of the sciatic nerve, the popliteal artery and vein, with their branches, also some lymphatic glands and much adipose substance. The nerves are superficial and external to the vessels, that is, nearer to the biceps ; the vessels are close to the bone, and near to the semi-membranosus muscle, the vein being superficial, and a little to the outer side of the artery ; two or three lymphatic glands are connected to the latter ; and a quantity of fat, which is of a peculiar soft consistence, intervenes between the nerve and vessels. The course of the peronseal nerve has been already noticed. The posterior tibial nerve descends nearly verti- cally between the hamstring muscles and the heads of the gastrocne- mius, and then runs beneath the solaeus, and over the poplitaeus ; above it lies to the outer side of, and at some distance from, the artery, but below it is in close contact with it, and to its tibial or inner side ; it then accompanies the posterior tibial vessels down the leg, and along the inner side of the heel, to the sole of the foot, in which course it shall be examined afterwards. In the ham this nerve sends off muscular branches, also the posterior or external saphenns nerve, which accompanies the posterior saphena vein along the back of the leg, towards the outer ankle, behind which it passes to the ex- ternal and superior part of the foot, where it is distributed : this nerve is by some called "communicans tibialis." The popliteal artery de- scends obliquely outwards through this space, and at the lower edge of the poplitreus muscle divides into the anterior and posterior tibial arteries ; in this course it sends off many muscular and five articular branches ; the latter supply the ends of the bones and the synovial membrane of the knee-joint. The popliteal vein accompanies the artery, lying superficial and somewhat external to it ; it receives branches which correspond to those of the artery, and it is joined in- feriorly by the lesser or posterior saphena vein. Next proceed to the dissection of the leg. SECTION VI. DISSECTION OF THE LEG. REMOVE the integuments of the leg and foot ; on the plantar surface of the latter they are always remarkably hard and thick, even in the foetus, particularly beneath the heel and the first and last joints of the toes : in these situations, also, the subcutaneous fat has a peculiar gra- imlatrd structure, being intersected by tendinous bands, which pass from the skin to the plantar fascia. Beneath the integuments of the leg we find two cutaneous veins, the internal and external saphena ; 384 DUBLIN DISSECTOR. the internal saphena is large and regular, and has numerous branches ; it commences by small veins from the upper surface of the toes, and from the dorsum of the foot ; these run towards the inner malleolus, and unite in one large vessel, which ascends along the inner side of the leg, receiving in its course numerous branches from the integu- ments ; it then passes behind the inner condyle of the femur, and, ascending along the inner and anterior part of the thigh, terminates in the femoral vein about an inch and a half below Poupart's ligament. On the thigh this vein is accompanied by small nerves, which are derived from the lumbar plexus and from the anterior crural ; along the leg the saphenus nerve, a branch of the anterior crural, is attached to it, and winds round it. The posterior or external saphena vein commences behind the external ankle from the junction of several small veins from the integuments of the heel and the sole of the foot ; it ascends along the surface of the gastrocnemius muscle, accompanied by the communicans tibialis nerve. At the ham this vein in general joins the popliteal vein, but sometimes it here turns inwards and joins the internal saphena vein, with which it always communicates in its course along the leg. Several cutaneous nerves are distributed to the leg, namely, the internal saphenus from the anterior crural, the pos- terior saphenus or communicans tibialis from the posterior tibial, and several cutaneous branches from the peronaeal and anterior tibial nerves, which perforate the fascia of the leg on its outer and anterior part, and are distributed to the integuments of the leg and foot. The fascia of the leg is derived partly from the fascia lata of the thigh ; it also receives additional fibres from the tendons around the knee joint, namely, the rectus and vasti anteriorly ; the vastus exter- nus and biceps externally ; the sartorius, gracilis, and inner ham- string internally ; it adheres to the head of the tibia and fibula, to the spine of the tibia, near its whole length, to the annular ligaments of the ankle joint, and to the malleoli ; it can scarcely be said to exist on the anterior surface of the tibia, which is only covered by the skin and periosteum : it is stronger superiorly than inferiorly. Near the ankle it again increases in strength from its connexion to the malleoli and to the annular ligaments ; these are three in number, anterior, inter- nal, and external. The anterior annular ligament is a little above the joint ; it is somewhat square, and stronger externally than inter- nally ; in the latter situation it is attached to the malleolar process of the tibia and to the os naviculare ; in the former to the external mal- leolus, and to the upper part of the os calcis ; it consists of two layers, which, by separating and re-uniting, form three rings or sheaths for the tibialis anticus and the two extensor tendons ; the anterior tibial vessels and nerves also pass beneath it. The internal is broader than the anterior ; it is attached to the internal malleolus and to the os cal- cis, forms a sort of arch over the groove or canal in which the three flexor tendons and the plantar nerves and vessels run. The external, short and narrow, is attached to the end of the external malleolus and to the os calcis ; it binds down the peronaeal tendons. The fascia of DUBLIN DISSECTOR. 385 the leg is thin posteriorly ; near the heel it is indistinct : on either side it is roiiiuvU'd to the sheaths of the tendons that pass round the mal- Icoli; and on each side of the tendo Achillis it sends in a lamina to join the fascia which covers the deep muscles of the leg, and which will be noticed presently : it serves to confine the muscles in their situ- ation, and to give origin to many of their fibres, to which, therefore, it adheres above, but not below ; this last effect is further accomplished by inter muscular bands or septa, which pass in from the fascia, be- tween the extensor and peronaei muscles, attached to the tibia, fibula, and interosseous ligament. From the anterior annular ligament a thin fascia is extended over the dorsum of the foot ; that covering the sole of the foot, the plantar fascia, is remarkably strong; it arises from the extremity of the os calcis, narrow, but thick and strong ; passes forwards, expands, and divides into three parts, which lie on different planes, and which, by sending in two processes, serve to se- parate the plantar muscles into three orders, the internal, middle, and external ; the lateral portions are attached to the sides of the tarsus and metatarsus ; the internal portion is the weakest : the middle divi- sion jg the strongest, and on a plane inferior to the internal. As this middle portion expands beneath the plantar muscles, it is strengthened by transverse fibres, and near the base of the toes it divides into five fasciculi ; these diverge, and opposite the head of each metatarsal bone subdivide into two fasciculi, which pass along the sides of the meta- tarso-phalangal articulations, and are inserted into the lateral liga- ments of these joints, and into the sheaths of the flexor tendons ; be- tween these fasciculi the tendons pass, also the digital vessels and nerves of each toe. The plantar fascia possesses the same strength as ligamentous structure. Use, it serves to retain the arched form of the foot, and to protect the plantar muscles, vessels, and nerves, from pres- sure ; it also gives attachment to several muscular fibres. The skin and areolar tissue are directly connected to the fascia of the leg and foot, so that no distinct superficial fascia exists between them. The muscles of the leg may be divided into anterior, external, and pos- terior. SECTION VII. I>I->i:OTION OF THE MUSCLES ON THE ANTERIOH AND EXTERNAL I 'ART OF THE LEG. THE muscles on the forepart of the leg are four in number, viz., the tibialis anticus, extensor pollicis, extensor communis, and peronams tcrtius. The muscles on the outer side of the leg are the peronreus longus and brevis. Almost all these muscles are connected to each other superiorly, so that they cannot be perfectly separated from 2 c 386 DUBLIN DISSECTOK. Fig. 61.* each other ; they all adhere to and partly arise from the fascia of the leg ; therefore, when exposed, they present a rough surface supe- riorly. 1. TIBIALIS ANTIC us, on the outer side of and next the tibia, somewhat triangular, large and fleshy above, tendinous below, arises tendinous and fleshy from the outer part of the two superior thirds of the tibia, from the head of the fibula, from the inner half of the inter- osseous ligament, from the fascia of the leg, and from the intermuscular septa. The fibres descend obliquely inwards, end in a strong and flat tendon which crosses from the outer to the forepart of the tibia, runs through a distinct ring in the annu- lar ligament, near the internal mal- leolus, passes forwards and inwards above the astragalus and naviculare, increases in breadth, and is inserted into the inner side of the great or internal cuneiform bone, also by a tendinous slip into the base of the first metatarsal bone, or that of the great toe. Use, to flex the ankle, to adduct the foot, and to raise its inner edge from the ground ; to turn the toes inwards, also to support the leg when standing, and prevent it bending backwards. This muscle is superficial through its whole length ; the tendon, at its insertion, is partly concealed by the abductor and flexor pollicis brevis ; superiorly it is external to the tibia, inferiorly it is anterior to it : the extensor com - munis and extensor pollicis, the anterior tibial vessels and nerve are to its outer or fibular side ; a small * The muscles of the anterior and external part of the leg. 1. The superior extremity of the tibia. '2. A portion of the llgamentum patellas. 3. The subcu- taneous surface of the tibia. 4. The tibialis anticus muscle. 5. The extensor digitorum longus. 6. The extensor pollicis proprius. 7. The pcronaeus tertius. 8. The peronajus longus. 9. The;perona3us brevis. 10. A portion of the sol;eus muscle. 11. Edge of the gastrocnemius muscle. 12. The external malleolus. 13. The anterior annular ligament of the tarsus. 14. The extensor digitorum brevis. 15. The tendo Achillis. I>IS>K( TOK. 387 bursa separates its tendon from the upper part of the internal cuneiform bone ; another hursa in general surrounds it as it is passing over the synovial membrane of the ankle joint. 2. EXTKNSOI: DKJITOKIM Lo\<;i s arises tendinous and fleshy from the external part of the head of the tibia, from the head of the iibula, and from about three-fourths of this bone, from part of the interosseous ligament, from the fascia of the leg, and its intermuscular septa ; the fibres descend obliquely inwards ; a little below the middle of the leg they end in three flat tendons, which pass under the annular ligament through a ring common to these and to the peronaeus tertius, and extend forwards over the dorsum of the foot, the internal of the three tendons here divides into two : the four tendons now extend along the dorsum of each of the four external toes (the great toe does not receive any), and are inserted into the last phalanx of each. Use, to extend the toes and flex the ankle. This muscle is superficial ; superiorly, it lies between the tibialis anticus and peronaeus longus, and is connected to both. In the middle of the leg it is between the extensor pollicis and peronaeus brevis ; on the dorsum of the foot its tendons cross at an acute angle those of the extensor brevis, which separate the former from the bones of the tarsus. Opposite each of the four metatarso-phalangal joints one of its tendons unites with the inner border of the corresponding dee)) or accessory tendon, and both expand into the dorsal aponeurosis of the toe. This, similar to that upon the fingers, covers the dorsum of the first phalanx, and receives additional fibres from the lumbri- cales and interossan. Opposite the joints between the first and second phalanges these fibrous sheaths divide into three fasciculi ; the middle is inserted into the base of the second phalanx, the lateral pass over the sides of the joint, then unite on the dorsum of the second phalanx, and are inserted into the base of the last. 3. EXTKNSOU POLLICIS PROPKIUS arises tendinous and fleshy from the inner edge of the middle third of the fibula, and from the interosseous ligament nearly as low down as the ankle ; a few fibres also proceed from the lower part of the tibia ; its origin seldom ex- tends above the middle third of the leg ; the fibres descend obliquely forwards to a tendon which passes beneath the annular ligament, then runs forwards over the astragalus, navicular, and cuneiforme internum ; the tendon next passes over the first metatarsal bone, and is inserted by two tendinous fasciculi, one into the base of the first phalanx, which also gives off an expansion on either side, and the other into the base of the second or last phalanx of the great toe. Use, to ex- tend the great toe and flex the ankle ; it may also adduct the foot, and rotate it inwards, and both this and the former muscle may, from the obliquity of their course, turn the toes outwards, and slighth raise the inner border of the foot. The upper and middle portions of this muscle arc overlapped and concealed by the tibialis anticus and extensor communis, between which muscles it is situated; its tendon is superficial ; the anterior tibial nerve and vessels separate it from the tibialis anticus above, and from the extensor communis 2 c 2 388 DUBLIN DISSEOTOK. below ; it lies on the fibula and interosseous ligament above ; inferiorly it crosses over the tibial vessels, the synovial membrane of the ankle joint, and bones of the tarsus ; on the foot it crosses superficially the extensor brevis, and is on the inner side of the dorsal artery of the foot. 4. PERON^EUS TERTIUS, or anticus, appears to be a portion of the extensor communis, and in some cases cannot be separated from it ; it arises from the anterior surface of the lower half of the fibula ; the fibres pass forwards to a tendon which descends, along with that of the extensor communis, beneath the annular ligament; it then passes forwards and outwards, and is inserted broad and thin into the base of the fifth metatarsal bone, and it frequently sends a band of fibres to join the fourth tendon of the extensor communis. Use, to extend the little toe, to flex the ankle, to abduct the foot and raise its outer edge. This muscle is sometimes wanting, an additional tendon from the ex- tensor communis will then supply its place ; it is superficial ; on the foot it conceals the extensor brevis, which may be next examined. EXTENSOR DIGITORUM BREVIS, is the only muscle situated on the upper surface of the foot ; it arises tendinous and fleshy from the upper and anterior part of the os calcis, in front of the groove for the pero- nasus longus, also from the cuboid bone, the astragalus, and the an- nular ligament ; it forms a flat, fleshy belly, which passes forwards and inwards, divides into four fasciculi, which soon end in four tendons, of which the two internal are the strongest ; the little toe does not receive any ; these tendons are inserted thus : the first or most in- ternal into the base of the first phalanx of the great toe, passing beneath its long extensor at an acute angle, and crosses the dorsal artery of the foot as it is about to sink between the first and second metatarsal bones ; the three other tendons join the outer edge of the corresponding tendons of the extensor digitorum longus, and assist in forming the aponeurosis which covers the dorsum of each toe. Use, to extend the toes and rotate the anterior part of the foot outwards. This muscle is partly concealed by the tendons of the long extensor and peronseus tertius ; it projects, however, behind and between them ; the tendons cross the metatarsal bones and the interossei muscles, beneath and in a different direction to the long extensor tendons, and as their obliquity is contrary to that of the latter, the combined action of both is to extend the toes directly : as the extensor tendons run in a more direct manner from the wrist joint to their insertion, there is no obliquity to correct, therefore there is no analogous mus- cle to this on the dorsum of the hand. The muscles on the outer part of the leg are the two peronaei. 1. PERONSEUS LONGUS, arises tendinous and fleshy around the head of the fibula, and from the adjacent surface of the tibia, from the upper half of the external angle of the fibula, from the fascia and intermuscular septa, the fibres descend obliquely backwards and out- wards, end in a strong, flat tendon, which passes behind the external malleolus, through a grove in the lower end of the fibula, in which it is bound down by a strong aponeurosis, lined by a synovial mem- DUBLIN DISSECTOR. 389 brane ; it then passes forwards, downwards, and inwards, through a similar groove in the os calcis and cuboid, in each of which it is secured by a synovial membrane, and a very strong fibrous sheath ; in the cuboid groove it is much thickened, and generally has a sesamoid bone or cartilage developed in it ; it next passes across the sole of the foot, above the plantar muscles, obliquely inwards and forwards, towards the metatarsal bone of the great toe, into the outer side of which, and of the adjacent sesamoid bone, it is inserted; also, into the internal cuneiform, and into the base of the second metatarsal bone. t/se, to extend the ankle joint, turn the foot outwards, and raise its outer edge, also to press the great toe against the ground as in walking ; in the leg this muscle is superficial, and is situated between the extensor communis anteriorly and the solgeus and flexor pollicis posteriorly, separated from both by aponeurotic septa ; in the sole of the foot it is above all the muscles there, and cannot be seen until these are removed. 2. PERON.EUS BREVIS, arises fleshy from the outer and back part of the lower half of the fibula, and from the intermuscular septa ; the fibres descend obliquely, end in a tendon which passes behind the external malleolus in the same groove as the peronaeus longus; it then passes forwards through a distinct groove in the os calcis, above the peronreus longus, and is inserted into the base of the metatarsal bone of the little toe, and into the os cuboides. Use, similar to the last. This muscle arises between the extensor longus and peronaeus longus, and descends between the peronasus tertius and the flexor pollicis longus, and partly concealed by the peronaeus longus ; it con- tinues fleshy lower down than it, and projects on either side of its tendon ; it is separated from the peronieus tertius by the external malleolus ; in the groove in the latter it is beneath the long peronaeal tendon, that is, nearer to the bone, but on the os calcis it is superior to it ; an aponeurosis sometimes unites its insertion to that of the ex- tensor tendon of the little toe. When the fibula is fractured near its malleolus, these two muscles, by raising the outer edge of the foot and turning its sole outwards, frequently dislocate the foot outwards, or the ankle, that is the astragalus, inwards : in a sprain or twisting of the ankle, these two tendons sometimes burst their sheath, are dis- placed, and lie in front of the malleolus, their action is then somewhat changed, and they become flexors of the ankle as well as abductors of the foot. In the dissection of the foregoing muscles we meet with the ante- rior tibial vessels and their branches ; also the peronaeal nerve and its divisions. The anterior tibial artery is a branch of the popliteal ; it passes forwards between the solaeus and popliteus, perforates the interosseous space, surrounded by some fibres of the tibialis posticus; it then descends obliquely inwards and forwards as far as the cleft between the first and .second metatarsal bones ; in its course down the leg it is placed at first between the tibialis anticus and extensor com- munis, in the middle of the leg between the former and the extensor 390 DUBLIN DISSECTOR. pollicis, and inferiorly between the tendon of the latter and that of the extensor communis ; above it lies on the interosseous membrane, below it passes over the tibia, the synovial membrane of the ankle joint, the astragalus, navicular, and cuneiform bones, and beneath the annular ligament and the internal tendon of the extensor cligitorum brevis ; in the leg the anterior tibial artery sends off, first, the recur- rent branch, which ascends on the outer and forepart of the head of the tibia, and meets the external articular arteries ; second, in its course along the leg, several muscular branches ; third, near the ankle, the two malleolar branches, of these, the external is the larger, and inosculates with a small artery (the anterior peroneal) which perfo- rates the interosseous ligament about two inches above the ankle joint ; on the tarsus, the anterior tibial artery, or, now called, dorsal artery of the foot, sends off the tarsal and metatarsal branches, which pass obliquely outwards, and supply the interossei muscles, the bones and joints of the tarsus and metatarsus ; between the two first metatarsal bones the anterior tibial divides into the superior and in- ferior branch ; the former supplies the integuments of the great toe ; the latter passes deep towards the sole of the foot, and joins the external plantar artery ; the anterior tibial artery is accompanied by two veins, which end in the popliteal vein. The peronceal nerve winds around the head of the fibula, perforates the peronaeus longus, and divides into several branches ; some of these supply the peronaeal muscles, others the integuments on the outer and fore part of the leg and foot ; and the continuation of the peronaeal nerve passes obliquely forwards and downwards, accompanies the anterior tibial artery, lying in general superficial, and to its fibular side. SECTION VIII. DISSECTION OF THE MUSCLES ON THE BACK OF THE LEG. THESE muscles are seven in number, and may be divided into a superficial and a deep layer ; the former consists of three, the gastroc- nemius, solaeus, and plantaris ; the latter of four, the tibialis posticus, flexor pollicis longus, flexor digitorum communis, and popliteus. The cutaneous nerves and veins, and the fascia, have been already noticed. 1. GASTKOCNEMIUS, large and thick, tendinous below, fleshy and aponeurotic above, and divided into two heads ; both are somewhat oval, convex behind, flat before ; the internal longer and larger than the external ; arises from a digital depression on the upper and back part of the internal condyle of the femur, and fleshy from the oblique ridge above it, behind the insertion of the adductor magnus, and on a plane posterior to the external head, which is not so long or so large, DUBLIN niSSKOTOK. 391 and which (irises in the same manner above the external condylefrom a pit above the groove for the popliteus tendon. The libres of each descend converging, and form two fleshy bellies, which unite a little below tlie knee in a middle tendinous line, and form the calf of the leg; the inner head constituting the larger portion. About the middle of the limb the muscle ends in a broad and flat tendon, which gradu- ally unites with that of the solams underneath, and both form the strong tendon called tendo AchiUis, which is inserted into the lower and back part of the os calcis. Use, to extend the ankle joint, and thus, by raising the heel from the ground, to lift the weight of the whole body, and throw it forwards on the toes, as in progression ; to ilex the knee joint, also to secure this articulation against displace- ment, by preventing the condyles of the femur slipping backwards off those of the tibia. This great muscle is superficial, a small portion of its internal head is overlapped by the semi-membranosus ; its deep surface is more aponeurotic than its superficial ; the lower angle of the popliteal space separates its two heads ; in this angle the poph'teal ves- sels, posterior tibial nerve, and plantaris muscle, are contained ; a bursa is placed between each head and the condyle of the femur, which it covers ; a sesamoid bone or tubercle often exists in each, particu- larly the outer : these support the condyles like strong capsules : the external head conceals the tendon of the popliteus ; the internal co- vers the deep processes of the semi-membranosus tendon and an inter- vening bursa, also the insertion of the popliteus : the gastrocnemius covers the greater part of the solonis, therefore to examine the latter detach the heads of the former from the condyles, and separate it from the soLeus to within two or three inches of the heel, or cut the muscle transversely about the centre, and raise the upper portion, whereby its structure will be seen. The plantaris muscle is now also exposed. 2. PLANTAKIS arises fleshy from the back part of the femur, above the external condyle, and from the posterior ligament of the knee ; it is connected to the external head of the gastrocnemius, forms a small, pyramidal, fleshy belly, which descends obliquely inwards, crosses the popliteal vessels, and ends in a flat tendon (the longest in the body), which descends between the gastrocnemius and solaeus. When the tendons of these muscles are about to unite, that of the plantaris be- comes superficial, and descends along the inner side of the tendo Achillis to the heel, and is inserted into the posterior part of the os calcis. a little anterior to the tendo Achillis ; it has also some con- nexion to the plantar fascia and subcutaneous tissue. Use, to extend the foot, and turn it inwards, also to make tense the fascia, and to flex the knee ; its origin is partly concealed by the external head of the gastrociicniius ; its tendon also is at first covered by this muscle, but interiorly it is superficial. This muscle is sometimes wanting ; it may probably be considered as rudimentary rather than essential ; the ten- don is often found so long and loose, and even coiled, that we can scarcely suppose the muscle had been accustomed to act, at least with any force. In most animals it is better developed in proportion than in man ; in the quadrumana it acts as a tensor of the plantar fascia, 392 DUBLIN DISSECTOR. and in quadrupeds it answers to the perforated flexor of the toes ; but in man the great muscles of the calf preponderate over all other ani- mals, their superior development being obviously in relation to the erect position he is destined to enjoy. In some instances the plantaris tendon is short and tense ; in such the muscle may rupture it, an accident which has been noticed by surgical writers. 3. SOI^EUS, of an oval and flattened figure, consists superiorly of two heads, which are not so distinct from each other as those of the gastrocnemius ; the external is longer and larger than the internal, and arises from the back part of the head and from the superior third of the fibula, behind the peronasus longus : the internal arises from the middle third of the tibia, commencing below the oblique insertion of the popliteus ; the two heads are connected by a strong tendinous arch, beneath which pass the posterior tibial nerve and vessels ; all the fibres descend and form a large oval belly, which continues fleshy lower than the gastrocnemius. A tendon is formed first on its super- ficial surface, and is gradually united to that of the gastrocnemius to form the tendo Achillis. This strong tendon is broad and thin above, narrow and depressed in the middle, and round and thick below ; it is composed of strong vertical fibres, which descend behind the os calcis, over a bursa, covering a cartilaginous impression on that bone, and is inserted into a rough surface below that. Occasionally a small bursa is also found between it and the skin. This muscle is almost entirely concealed by the gastrocnemius ; a little below the middle of the leg, however, it projects on each side of the tendon of the latter, and forms the lower calf ; it covers the deep-seated muscles, vessels, arid nerves. Use, to assist the gastrocnemius in extending the ankle, but it cannot exert any influence on the knee-joint as that muscle does. When standing, the solaeus supports the leg, and resists the ten- dency of the body to fall forwards, while the gastrocnemii strengthen the back part of the knee joint, press the condyles forwai'ds, and re- sist their tendency to rotate backwards and upwards in the superficial tibial cavities ; they can also flex the knee when the anterior exten- sors permit, but, as they are very close to the fulcrum, their action in this respect is feeble, whereas the combined actions of these two mus- cles, which may be considered as one powerful triceps or quadriceps extensor pedis, and which is the largest muscle in the body, are most powerful ; they are the principal agents not only in maintaining the erect posture, but also in all locomotive exertions, such as walk- ing, running, dancing, leaping, &c. ; they are peculiarly and very favourably circumstanced for the exercise of power ; the lever, whereby they act, is of the second order, the toes being the fulcrum at one end ; the weight, which is the body, rests upon the astragalus in the ankle joint in the middle ; and the power, which is at the other hand, is re- presented by the insertion of the tendo Achillis into a rough projection on the lower part of the os calcis, and which insertion is perpendicular to the lever. A violent action of these powerful muscles occasionally ruptures the tendo Achillis, or tears off a fragment of the os calcis. Detach the solseus from its origin, and the strong, deep fascia of the DISSKCTOK. 30: leg is exposed : this fascia is partly derived from F'9- "-' iii-inembranosu? and popliteus, and partly from the more superficial fascia of the leg ; it ad- II.TCS to the tibia and lilmla, to the solaeus, and to the deep muscles : inferiorly it is strong, and con- nected to the sheaths of the tendons that pass be- hind the malleoli, and to the lateral annular liga- ments of the ankle ; raise it, and clean the four following muscles : popliteus, two long flexors of the toes, and the tibialis posticus ; the first is con- fined to the region of the knee, or ham, but the other three extend along the leg into the foot, and are all reflected or bent round the inner ankle, ver- tical in the leg, horizontal in the foot. 4. POPLITEUS, situated obliquely at the upper and back part of the leg, bound down by a strong fascia, behind the knee, above the other muscles in this region, flat and triangular ; arises by a round and very strong tendon from a depression on the external surface of the outer condyle, be- low the origin of the outer head of the gastroc- nemius and of the external lateral ligament ; de- scends obliquely inwards and backwards, above the head of the fibula, and along the external semilunar cartilage, to which it is connected by the synovial membrane of the knee, and by a few tendinous fibres ; becomes broad and fleshy, and is inserted into a flat, triangular surface, which occupies the superior fifth of the posterior surface of the tibia. Use, to bend the knee, and, when bent, to twist the foot and toes inwards ; it may also assist, when the limb is extended, in rotating the knee outwards : it supports the external semi- lunar cartilage, and moves it slightly, so as to adapt its situation to the external condyle of the femur in the rotatory motions of the joint ; the popliteus is covered by the two heads of the gas- trocnemius, the plantaris, the external lateral li- gament, and the popliteal nerve and vessels ; it is superior to the inner head of the solaeus, and passes * The deep layer of muscles on the back of the leg. 1. The lower extremity of the femur. % 2. The internal condyle. 3. The external condyle of the same bone. 4. The tendon of the semi-membranosus muscle. ;>. The ligamentnm posticum of Winslow. 9- c -3.* inferior set. The integuments and fascia in the sole of the foot have been already noticed. The muscles here are very nume- rous : they may be divided into four lami- nas ; these are tolerably distinct about the middle of this region, but at either side this arrangement is rather artificial ; the two intermuscular processes of the plantar fascia also divide these laminae into three com- partments, an internal, a middle, and an external. The muscles of the first, or su- perficial layer, are the abductor pollicis, flexor digitorum brevis, and. abductor mi- nimi digiti : in the second layer are the long flexor tendons, the accessory muscle, and the lumbricales. The third layer consists of the flexor pollicis brevis, adductor polli- cis, transversalis pedis, and flexor minimi digiti. In the fourth layer are the inter- ossei muscles, and the tendon of the pero- naeus longus. ABDUCTOR POLLICIS arises tendinous and fleshy from the lower and inner part of the os calcis, from the internal annular li- gament, the plantar aponeurosis, and inter- nal intermuscular septum ; the fibres pass forwards and inwards, and are inserted tendinous into the internal sesamoid bone, and into the internal side of the base of the first phalanx of the great toe. Use, to separate the great toe from the others ; it can also flex it. This muscle is by some writers called the adductor pollicis, its action being then referred to the mesial line of the body ; it is the most internal of the plantar nius- * The first or superficial, and part of the second layer of muscles in the sole of the foot, the plantar fascia having been removed. 1. The inferior surface of the os calcis. 2. The abductor pollicis. 3. The flexor digitorum brevis perforatus. 4. The abductor minimi digiti. 5. The tendon of the flexor pollicis longus. 6. 6. 6. 6. The lumbricales. 7. One of the tendons of the flexor digitorum longus passing through the slit in the corresponding tendon of the flexor digitorum brevis. DUBLIN DISSECTOR. 397 cles, and is superficial ; the fascia covering it is very thin ; the long tendons and plantar vessels and nerves pass between its heads or ori- gins from the internal malleolar region into the sole of the foot ; a septum from the plantar fascia alone separates its outer border from the following muscle. FLEXOK DIGITOKUM BREVIS PERFORATUS, short, thick, and nar- row behind ; arises from the inferior and rather from the internal part of the os calcis, from the internal annular ligament, the plantar apo- neurosis, and intermuscular septa ; it fonns a fleshy mass, which, pass- ing forwards, divides about the middle of the foot into four delicate muscles, which soon end in tendons; these accompany the flexor longus communis into the tendinous and synovial sheaths, beneath the phalanges of the four outer toes : each tendon is slit opposite the base of the second phalanx, and, having transmitted the long flexor ten- don, is then folded out on the inferior surface of the second phalanx, and again bifurcates close to the bone, and is inserted into its lateral borders, above the long flexor tendon, having been previously beneath it. Use, to assist the long flexor, to strengthen the plantar fascia, and to preserve the arch of the foot. This muscle is immediately above the strong central portion of the plantar fascia, from which a con- siderable portion of it arises, therefore it always presents a rough surface when dissected ; it is beneath the plantar vessels and nerves, the long flexor tendons, the accessory muscles, and the lumbricales ; it is joined to the abductor pollicis posteriorly, but anteriorly is separated from it by the tendon of the flexor pollicis longus ; the fourth, or the external of its tendons, or that for the little toe, is sometimes wanting. This muscle is analogous to the flexor sublimis of the fingers, but much smaller, and wants the vertical portion. ABDUCTOR MINIMI DIGITI is situated along the outer edge of the foot, arises tendinous and fleshy from the outer side of the os calcis, and from a strong ligament which extends from this to the fifth meta- tarsal bone, also from the bone of the latter, from the plantar fascia, and its external intermuscular septum; inserted tendinous into the outer side of the base of the first phalanx of the little toe, and into the adjoining surface of the metatarsal bone. Use, to separate the little toe from the others, and to flex it. This muscle is also superficial ; the fascia covering it is very strong ; it is the most external of the muscles in this region. Detach this first layer of muscles from their posterior attachments, and throw them forwards towards the toes ; the tendons of the flexor pollicis and communis are now exposed, also the accessory muscle and the lumbricales ; all these constitute the second layer of the plantar muscles, and which is partially concealed by the first. The tendon of the flexor longus digitorum communis is seen pass- ing from the inner side of the os calcis to the middle of the plantar region, where it divides into its four tendons, which have been already described as entering the sheaths on the inferior surface of the four outer toes, passing through the slits in the tendons of the flexor brevis, 398 DUBLIN DISSECTOR. and then inserted into the last phalanx of Fig.CA. 1 each toe. The tendon of the flexor pollicis longus is now also seen passing above the former, to which it is united by a tendinous fasciculus, and then proceeding forwards to its insertion to the base of the great toe. MUSCULUS ACCESSORIUS, or flexor digi- torum accessorius, square, flat, and fleshy ; arises bifurcated, fleshy and tendinous from the inferior and lateral borders of the os calcis, forms a flat and somewhat square, fleshy belly, which, proceeding forwards, is inserted into the upper and outer part of the tendon of the flexor digitorum longus, just before it divides ; an expansion from the flexor pollicis longus also joins it, and ex- tends to the flexor communis. Use, to assist the long flexor, and to counteract its obli- quity by pulling it directly towards the heel. This muscle lies above the flexor digitorum brevis and the plantar vessels and nerves, and beneath the os calcis and calceo-cuboid ligaments. There is no analogous muscle to this in the hand, as there the flexor tendons pass directly over the centre of the carpus. LUMBRICALES are four small muscles which arise tendinous and fleshy from the angles between the tendons of the flexor di- gitorum longus ; there is none for the great toe : the first or the internal one is the largest. These four muscles proceed forwards along the internal edge of the long flexor tendons ; each ends in a thin aponeurosis, which is inserted into the internal side of the first phalanx of the four lesser toes, and joins the tendinous expansion of the extensor tendons on the dorsum of the toes. Use, to adduct and to assist in flexing the four toes ; they may also extend their second and last phalanges. These muscles are covered in the sole of the foot by the superficial layer, but emerge from beneath this and the plantar fascia in the interstices between the sheaths of the flexor tendons ; their tendinous insertions are superficial, and are best seen on the dorsum of the toes. They are analogous to the four lum- bricales in the hand, which also arise from the deep or perforating flexors, and run along the radial side of each tendon, or that next the * The second and part of third layer of muscles in the sole of the foot 1 . The inferior surface of the os calcis. 2. A portion of the inferior calcaneo cuboid li- gament. 8. The tendon of the flexor digitorum longus dividing into its four por- tions. 4.4. The tendon of the flexor pollicis longus. 5. The musculus accesso- rius. 6.6.6.6. The Inmbricales muscles. 7.A portion of the flexor pollicis brevis. 8. Part of the flexor brevis minimi digiti. DUBLIN DISSECTOR. 399 thumb, so in the foot they run along that side which corresponds to the great toe ; hence, although they are described as running along the outer sides of the flexor tendons in the hand, and along the inner in the foot, yet still they are perfectly analogous, supposing the hand in the prone position, or the foot in the supine. Detach tliis second layer of muscles, and throw it also forwards towards the toes. The third layer of the plantar muscles consists of the flexor pollicis brevis, adductor pollicis, transversalis pedis, and flexor minimi digiti. FLEXOR POLLICIS BREVIS, narrow posteriorly, broad and notched Fig. 65.* anteriorly; arises by a strong tendon from the lower and anterior part of the os calcis, also from the cuboid and external cuneiform bone and their connecting ligaments ; it forms a fleshy belly which is inseparably connected to the abductor and adductor pollicis ; passes forwards and inwards, and divides into two short tendons ; inserted into the sesamoid bones beneath the first phalanx of the great toe. Use, to flex the first joint of the great toe, also to approximate this toe to the others. This muscle forms a sort of sheath for the tendon of the flexor pollicis longus, and is analogous to the short flexor of the thumb. ADDUCTOR POLLICIS is situated external to the last muscle, or more in the centre of the foot, is inseparably attached to it, and is the largest muscle in this plane ; it arises ten- dinous and fleshy from the strong calcaneo- cuboid ligament,* from the sheath of the pe- ronaeus longus, and from the base of the second, third, and fourth mctatarsal bones ; pu-so forwards and inwards, inserted along with the external portion of the last muscle into the external sesamoid bone. Use, to draw the great toe. outwards towards the others, also to flex it, so as to bring it beneath them. By some this muscle is named the abductor pollicis, its action being then re- ferred to the mesial line. TRANSVEKSALIS PEDIS arises by distinct, fleshy slips from the an- terior extremities of the four external metatarsal bones. The fibres pass inwards and forwards, converging to the external sesamoid bone of the great toe, into which they are inserted along with the last de- 'm* T h p thirtl and P art f the fourth layer of muscles of the sole of the foot 1 The interior surface of the os calcis. 2. The inferior calcaneo-scaphoid ligament' o. The inferior calcaneo-ciiboid ligament. 4. The flexor pollicis brevis. 5. The adductor polhcis. 6. The transversalis pedis. 7. The flexor brevis minimi di- tnti. 8. 8. b. The inferior interossei muscles. 9. The tendon of the peronseus longus, m its sheath, passing obliquely across the sole of the foot. 400 DUBLIN DISSECTOK. scribed muscle. Use, to approximate the toes, and to contract the transverse arch of the foot. There is no analogous muscle in the hand, except the anterior transverse fibres of the adductor pollicis. Behind this muscle, and nearly parallel to it, the strong calcaneo- cuboid liga- ment is observed ; also the tendon of the tibialis posticus dividing into several slips, which are inserted into the adjacent bones and ligaments. FLEXOR BREVIS MINIMI DIGITI arises tendinous and fleshy from the cuboid and fifth metatarsal bone, and from the sheath of the pero- naeus longus tendon ; it passes forwards and outwards, and is inserted into the inner side of the base of the first phalanx of the little toe. Use, to flex and adduct this toe. This muscle is connected to the ab- ductor minimi digiti ; it fills up the concavity of the fifth metatarsal bone. Detach these four muscles in this layer from the tarsus, and the fourth layer will come into view, namely, the tendon of the perona3iis longus and interossei muscles ; the former crosses the foot obliquely forwards and inwards from a deep groove in the ciAoid, beneath the cuneiform and metatarsal bones, to be inserted into the internal cu- neiform and into the base of the first and second metatarsal bones ; in this course this strong round tendon is enclosed in a tendinous sheath, which is lined by synovial membrane, and is attached to the several projections of the adjoining bones. Use, to serve as a strong, trans- verse ligament in strengthening the tarsus and metatarsus in that di- rection. This course and connexion of the tendon explain the action of the peronaeus longus muscle, namely, to extend the ankle joint, to elevate the external side of the foot, to depress its internal side, and to turn the point of the foot outwards. INTEROSSEI MUSCLES are seven in number ; three are seen in the sole of the foot, and four on the dorsum ; they fill up the interstices between the metatarsal bones : the three inferior are named interossei interni, or inferiores, and lie rather beneath or in the concavity of these bones than between them, the interosseous space being very nar- row ; they arise tendinous and fleshy from between the metatarsal bones of the four external toes, and are inserted tendinous into the inner side of the extensor tendon and of the base of the first phalanx of the three lesser toes. Use, they are all adductors of the toes, like the palmar interossei, that is, supposing the axis of the foot to be in the line of the second toe, and not, as in the hand, through the third or middle finger; they each arise from one metacarpal bone only, from its lower surface, and from the lower part of its inner side, that which looks towards the axis of the foot, and are inserted each into the inner side of the same toe ; none of them are attached to the first and second toes, but the adductor pollicis might be considered as belonging to this group. The first is between the second and third metatarsal bones, arises chiefly from the inner side of the third, and is inserted into the inner side of the first phalanx of the same or the middle toe ; this is the adductor medii digiti; the second is between the third and fourth metatarsal bones, arises chiefly from the inner side of the fourth, is inserted into the inner side of the first phalanx of the same toe, and is the adductor quarti digiti ; the third is between the fourth nrni.ix I>ISSKf the third toe. f'se, to separate the third toe from the second. The fourth or abductor digiti quarti is situated between the fourth and fifth metatarsal bones ; it arises from their opposite surfaces, and is inserted into the outer side of the first phalanx of the fourth toe from the three internal. All these muscles are covered by the long and short extensor tendons, and by a strong aponeurosis, which binds them down between the bones, and presses them towards the plantar surface; they conceal the inferior interossci, and are separated from them by a fine fascia derived from the plantar. ISoih set - of interossei -rve to >trcngthcn the metatarsus, and to press the metatar>al !."iie- tc-vther: they also serve to Hex the first joint ofthe four outer toes, but may aist in extending their last phalange. : these muscles can exert no influence on the great toe ; there is only one muscle between the two first metatarsal bones ; between the others there are two, therefore there are four superior or dorsal interossei muscles, but three inferior ; the latter are situated more in the concavity of each metatarsal bone than between these bones ; the superior are stronger and more tendinous than the inferior ; and are only partially covered by the long and short extensor tendons. In dissecting the muscles on the back of the leg, and those in the sole of the foot, we meet the posterior tibial vessels and nerve, and their principal branches. The posterior tibial artery is the larger branch of the popliteal; it descends obliquely inwards beneath the deep fascia and the superficial muscles, and over the tibialis posticus and flexor communis, to the fossa between the heel and inner ankle, it here ends in the two plantar arteries : in this course it gives off many muscular branches, also the peronaal artery ; the latter arises from the tibial, about an inch below the poplitseus ; it descends obliquely outwards along the back part of the fibula beneath the flexor pollicis longus ; behind and a little above the outer ankle, it divides into the anterior and posterior peronasal arteries ; the former perforates the interosseous space and joins the external malleolar artery ; the latter descends between the external ankle and the 'heel, and is distributed to the ligaments and adipose substance in that region. The two plantar branches of the posterior tibial artery are dis- tributed to the muscles and integuments of the foot and toes; the internal plantar is the smallei *. . the two, it supplies the muscles along the inner side of the tarsus : the external plantar, the large branch, runs across the foot obliquely outwards, towards the fifth metatarsal bonfCbetween the first and second layers of plantar muscles ; from the little toe it next runs obliquely forwards and inwards, towards the first metatarsal bone, above the second layer of the plantar muscles, and between the first and second metatarsal bones it joins the deep branch of the anterior tibial artery, and thus forms the great plantar arch of arteries, from the convexity of which proceed the digital arte- ries, to supply the toes. {See Anatomy of the Vascular System.) The posterior tibial artery and its several branches are accompanied by corresponding veins, all of which end in the popliteal vein. The pos- terior tibial nerve is the principal branch of the sciatic, it accompa- nies the posterior tibial artery, at first lying to its tibial, afterwards to its fibular side; in this course it sends off several small brandies to the deep and superficial muscles of the leg, and between the heel and ankle it divides into the two plantar nerves, which take the course of the corresponding arteries. In this internal malleolar region, when the integuments, fascia, and internal annular ligaments are removed, we find the three tendons and the posterior tibial nerves and vessels to have the following relation to each other : the tibialis posticus and flexor^communis tendons are bound close to the ankle ; about half an inch behind* these is the posterior tibial artery, accompanied by two veins ; tfie nerve is a little nearer to the heel ; and the tendon of the flexor pollicis lies about half an inch nearer to the latter. ,. 40 ERIOD 642-4493 BlOSCIENCl -< 40 Giannini ^ BOOKS MAY BE RECALLED AFTER 7 DAYS DUE AS STAMPED BELOW MAR 1 ta REG F I V F n iiAf^l f\ ^ inriv MAR 3 '99:> BI03CIENCES UNIVERSITY OF CALIFORNIA, BERKELEY O. DDO, 50m, 1/82 BERKELEY, CA 94720 U.C. BERKELEY LIBRARIES UNIVERSITY OF CALIFORNIA LIBRARY ,, ^_ .....