, 
 
THE LIBRARY 
 
 OF 
 
 THE UNIVERSITY 
 OF CALIFORNIA 
 
 PRESENTED BY 
 
 PROF. CHARLES A. KOFOID AND 
 MRS. PRUDENCE W. KOFOID 
 
HOLDEN'S MANUAL 
 
 DISSECTION OF THE HUMAN BODY 
 
 EDITED BY 
 
 LUTHEE HOLDER, P.E.C.S. 
 
 SURGEON TO ST. BARTHOLOMEW'S HOSPITAL, AND LECTURER ON ANATOMY AT THAT HOSPITAL; 
 
 MEMBER OP THE COUNCIL OF THE ROYAL COLLEGE Ob 1 SURGEONS OF ENGLAND J 
 
 SURGEON TO THE FOUNDLING HOSPITAL 
 
 AND 
 
 JOHN LAISTGTON, F.K.C.S. 
 
 ASSISTANT-SURGEON TO, AND DEMONSTRATOR OF ANATOMY AND OPERATIVE SURGETfY 
 
 AT ST. BARTHOLOMEW'S HOSPITAL ; SURGEON TO THE CITY ov 
 
 LONDON TRUSS SOCIETY 
 
 ILLUSTRATED WITH NUMEROUS WOOD ENG-RAVINO-S 
 
 THIRD EDITION 
 
 LONDON 
 JOHN CHURCHILL & SONS, NEW BURLINGTON STREET 
 
 MDCCCLXVIII 
 
Lilb 
 
 TO 
 
 THE STUDENTS 
 
 OF 
 
 ST. BARTHOLOMEW'S HOSPITAL 
 
 IN THE HOPE THAT IT MAY ASSIST THEM IN THEIR 
 ANATOMICAL STUDIES 
 
 K tyz parmal is gebwatcfc 
 
 BY THEIR FAITHFUL FRIEND AND WELL-WISHER 
 
 THE AUTHOR 
 
PREFACE 
 
 TO 
 
 THE THIRD EDITION, 
 
 WITHOUT DEPARTING from the original object of the Manual, new 
 matter has been added here and there to this edition, more es- 
 pecially concerning the Anatomy of the Brain, the Organs of the 
 Senses, and the Abdominal Viscera. 
 
 A few additional woodcuts have been introduced ; and the order 
 of dissection altered where it was considered advisable. 
 
 The author takes this opportunity of acknowledging that the 
 real work of preparing this edition has been done by his colleague 
 Mr. LANGTON, one of the Demonstrators of Anatomy at Saint 
 Bartholomew's Hospital. 
 
 65 (TOWER STREET , 
 October 1868. 
 
PREFACE 
 
 TO 
 
 THE SECOND EDITION. 
 
 IN THIS EDITION the author has most carefully revised the entire 
 work. Considerable additional matter has been introduced. 
 Many parts, which some students found obscure, have been 
 entirely re-written. 
 
 The object of the author throughout has been to be as concise 
 as possible, and to put the subject in as clear and practical a 
 light as is compatible with the faithful handling of its natural 
 difficulties. 
 
 It is hoped that the work, in its present form, is adapted, not 
 only for students, but for members of the profession who wish to 
 refresh their anatomical knowledge. 
 
 Most of the illustrations are the author's drawings from nature 
 on wood ; many he has taken from his own diagrams which he has 
 found useful in teaching ; others from photographs ; and for some 
 
X PREFACE TO THE SECOND EDITION. 
 
 he is indebted to the able pencil of Mr. GTODART, the ^Librarian of 
 the Hospital. The engraving has been accurately executed by 
 Mr. JOYCE, of Bolt Court. 
 
 P.S. The author suggests that students will find a great 
 advantage in colouring the woodcuts in light tints : the arteries 
 red, the veins blue, and the nerves yellow. 
 
 54 (TOWER STREET : 
 October 1861. 
 
PREFACE 
 
 TO 
 
 THE FIRST EDITION. 
 
 IF any apology be needed for the appearance of the present 
 Manual, it may be stated, without any wish to disparage the 
 labours of others, that the works of this kind hitherto published 
 seem to the author open to one or the other of two objections ; 
 either as being too systematic, and therefore not adapted for 
 the dissecting-room, or as obscuring* the more important features 
 of anatomy by a multiplicity of minute and variable details. 
 
 In endeavouring to supply a presumed deficiency, the author 
 has made it his special aim to direct the attention of the student 
 to the prominent facts of anatomy, and to teach him the ground- 
 work of the science ; to trace the connection, and to point out 
 the relative situation of parts, without perplexing him with 
 minute descriptions. 
 
 A concise and accurate account is given of all the parts of the 
 human body, the bones excepted, of which a competent knowledge 
 
Xll PREFACE TO THE FIRST EDITION. 
 
 is presupposed ; and directions are laid down for the* best method 
 of dissecting it. 
 
 The several regions of the body are treated of in the order 
 considered most suitable for their examination ; and the muscles, 
 vessels, nerves, &c. are described, as they are successively exposed 
 to view in the process of dissection. 
 
 The author has written the work entirely from actual observa- 
 tion : at the same time no available sources of information have 
 been neglected, the highest authorities both English and Foreign 
 having been carefully consulted. His acknowledgments are 
 especially due to F. C. SKEY, Esq. F.R.S., Lecturer on Anatomy 
 at St. Bartholomew's Hospital, for many valuable suggestions. 
 He is also much indebted to his young friend, Mr. W. CLUBBE, for 
 able assistance in dissections. 
 
 September 1851. 
 
A MANUAL 
 
 OF THE 
 
 DISSECTION OF THE HUMAN BODY. 
 
 
 DISSECTION OF THE SCALP. 
 
 AN incision should be made from the nose along the mesial line to 
 the occiput; another at right angles to the first from one side of 
 the head to the other. These incisions must not divide more 
 than the skin, that the subcutaneous vessels and nerves may not 
 be injured. 
 
 Strata com- ^ke severa ^ strata of tissues covering the skull-cap 
 posing the are 1, the skin ; 2, a thin layer of adipose tissue which 
 scalp. contains the cutaneous vessels and nerves and the bulbs 
 
 of the hair ; and by which the skin is very closely connected to, 
 3, the broad thin tendon of the occipito-frontalis muscle (aponeu- 
 rosis of the scalp) ; 4, an abundance of loose areolar tissue, which 
 permits the free motion of the scalp upon, 5, the pericranium, or 
 periosteum of the skull-cap. 
 
 Immediately beneath the skin, then, we expose the thin stratum 
 of adipose tissue which connects it to the aponeurosis of the scalp. 
 It forms a bed for the bulbs of the hair and for the ramifications 
 of the cutaneous arteries. The toughness of this tissue, in which 
 the arteries ramify, does not permit them to retract when divided ; 
 hence the haemorrhage which follows incised wounds of the scalp ; 
 hence, also, the difficulty of drawing them out with the forceps. 
 The blood-vessels of the scalp are derived, in front, from the 
 
 i; 
 
2 DISSECTION OF THE SCALP. 
 
 supra-orbital and frontal arteries, branches of the internal carotid ; 
 on the sides, from the temporal ; behind, from the occipital and 
 posterior auricular, branches of the external carotid. Trace the 
 leading trunks, and observe that they subdivide into branches, 
 which inosculate freely, and finally form a vascular network among 
 the bulbs of the hair. A few small branches here and there dip 
 down through the aponeurosis of the scalp to the pericranium. 
 The veins accompany the arteries. 
 
 n . . This cutaneous muscle is closely connected to the 
 
 Uccipito- ^ * 
 
 frontalis scalp. It consists of two fleshy portions, one on the 
 muscle. occiput, the other on the forehead, connected by a broad 
 aponeurosis. The origin of the muscle takes place from the outer 
 "two-thirds of the upper curve on the occipital bone, and the ad- 
 joining part of the mastoid process. The fibres ascend over the 
 back of the head, and terminate in the common aponeurosis. The 
 frontal portion, commencing in an arched form from the common 
 aponeurosis near the frontal suture, descends over the forehead, 
 and terminates partly in the skin of the brow, partly in the orbi- 
 cularis and corrugator supercilii. Some fibres run down the nose 
 under the name of the pyramidalis nasi. The aponeurosis of the 
 scalp is continued over the temples and side of the head, gradually 
 changing from tendinous into fibro-cellular tissue. This muscle 
 enables us to move the scalp backwards and forwards. But its 
 chief action is as a muscle of expression. It elevates the brows, 
 and occasions those transverse wrinkles in the expression of sur- 
 prise. Like the other muscles of expression, it is supplied by the 
 facial nerve. 
 
 There are several small muscles to move the cartilage 
 
 of *ke ear ' In man the y are thin ancl P ale ' kut in 
 animals who possess a more delicate sense of hearing, 
 they are much more developed, for the purpose of quickly direct- 
 ing the cartilage of the ear towards the pulse of the air. 
 
 To indicate the position of this muscle the student 
 s ^ ould ^ raw down the upper part of the pinna of the 
 ear, when it will be found immediately under the ridge 
 of skin so produced. It arises from the aponeurosis of the scalp, 
 
NERVES OF THE SCALP. 3 
 
 and is inserted into the cranial aspect of the upper part of the 
 concha. 
 
 The situation of this muscle, which is smaller than 
 
 M. attrahens ^ e preceding, is indicated by the prominence of skin, 
 
 produced by drawing backwards the front part of the 
 
 helix. It arises from the aponeurosis of the occipito-frontalis, and 
 
 is inserted into the front of the helix. 
 
 This muscle is exposed by reflecting the skin from 
 M. retrahens foe ridge produced by drawing the pinna forwards. It 
 proceeds from the base of the mastoid process to the 
 lower part of the concha. The retrahens and the attollens aurem 
 are supplied by the auricular branch of the facial nerve; the 
 attrahens by an offset from the temporal branch of the same 
 nerve. 
 
 The supra-orbital nerve is a branch of the ophthalmic 
 Nerves of division of the fifth. It emerges from the orbit through 
 the notch of the frontal bone, and subdivides into 
 branches, which are covered at first by the fibres of the orbicularis 
 and occipito-frontalis ; but they presently become subcutaneous : 
 some of them may be traced over the top of the head as far as the 
 occipital bone. 
 
 The supra-trochlear nerve is an offset from the frontal branch 
 of the ophthalmic division of the fifth. It appears at the inner 
 angle of the eyelids, and supplies the skin of the forehead. 
 
 The superficial temporal nerves ramify in company with the 
 arteries of the same name. Some of them are derived from the 
 superior, and some from the inferior maxillary division of the fifth 
 pair ; others from the facial. 
 
 The posterior auricular nerve is a branch of the facial, and 
 runs with its corresponding artery behind the pinna of the ear, to 
 supply the attollens and retrahens aurem, and the posterior belly 
 of the occipito-frontalis. 
 
 The great occipital nerve is the posterior branch of the second 
 cervical nerve. After passing through the complexus, it appears 
 on the occiput with the occipital artery, and divides into wide- 
 spreading branches, which supply the skin over the occiput. 
 
4 DISSECTION OF THE SCALF. 
 
 The small occipital nerve, a branch of the anterior division of 
 the second cervical (p. 15), runs along the posterior border of 
 the insertion of the sterno-mastoid, and supplies the scalp. 
 Points of Raise the aponeurosis of the scalp, and observe the 
 
 surgical quantity of loose areolar tissue which intervenes between 
 it and the pericranium. This tissue never contains fat. 
 There are some points of surgical interest concerning it : 1. Its 
 looseness accounts for the extensive effusions of blood which one 
 often sees after injuries on the head. 2. It admits of large flaps 
 of the scalp being detached from the skull-cap ; but these flaps do 
 not mortify because they carry their blood-vessels with them. 
 3. In phlegmonous erysipelas of the scalp, it becomes infiltrated 
 with pus and sloughs ; hence the necessity of making incisions ; 
 for the scalp will not lose its vitality, and liberate the sloughs like 
 the skin of other parts under similar conditions, because its vessels 
 run above the diseased tissue, and therefore its supply of blood is 
 not cut off. 
 
 The absorbent vessels of the scalp run most of them backwards 
 towards the occiput ; a few run towards the root of the zygoma, 
 where they enter the absorbent glands in those situations respec- 
 tively. Here, therefore, one finds glandular enlargements when 
 the scalp is diseased. 
 
 To examine the brain and its membranes, the skull-cap must 
 be removed about half an inch above the supra-orbital 'ridges in 
 front, and on a level with the occipital protuberance behind. It 
 is better to saw only through the outer table of the skull, and to 
 break through the inner with a chisel. In this way the dura 
 mater and the brain are less likely to be injured. On removing 
 the skull we expose a tough fibrous membrane, the dura mater, 
 which forms the most external of the membranes of the brain. 
 
 These arteries ramify between the skull and the dura 
 mater - Their course may be traced by the grooves 
 which they make in the bones. The most important is 
 the ' arteria meningea media,' a branch of the internal maxillary 
 artery. It enters the skull through the foramen spinosum, and 
 divides into two principal branches ; one runs in a groove along 
 
DURA MATER. o 
 
 the anterior inferior angle of the parietal ; the other curves back- 
 wards over the temporal bone, and subsequently ramifies on the 
 parietal bone. The artery is accompanied by two veins, which 
 empty themselves into the internal maxillary vein. The arteria 
 meningea parva and a meningeal branch from the ascending 
 pharyngeal artery also supply the dura mater and bones of the 
 middle fossa. The other meningeal arteries are of insignificant 
 size. The anterior come from the ethmoidal branches of the 
 ophthalmic. The posterior come from the occipital and vertebral: 
 these enter the skull through the foramen jugulare and the fora- 
 men magnum respectively. 
 
 The position of the meningeal arteries renders them liable to 
 injury in fractures of the skull ; hence extravasation of blood 
 between the skull and dura mater is one of the common causes of 
 compression of the brain. 
 
 This is so called from the notion that it gave rise 
 to all the other membranes in the body. It is rough 
 on its outer aspect, where it is more or less adherent to the 
 inner surface of the skull. Internally it is smooth and shining, 
 being lined by the parietal layer of the arachnoid membrane. Its 
 remarkably tough and fibrous structure adapts it exceedingly well 
 to the four purposes which it serves: 1. It forms the internal 
 periosteum of the skull ; 2. It forms, for the support of the lobes 
 of the brain, three partitions namely, the falx cerebri, the falx 
 cerebelli, the tentorium cerebelli ; 3. It forms the sinuses or 
 venous canals which return the blood from the brain ; 4. It forms 
 sheaths for the nerves as they leave the skull. 
 
 ^ Of the partitions formed by the dura mater for the 
 
 s; tionrformed support of the lobes of the brain, two are vertical, and 
 J^ by dura separate the two hemispheres of the cerebrum and 
 those of the cerebellum ; the third is nearly horizontal, 
 O and supports the posterior cerebral lobes. 
 
 . The great partition is named, from its resemblance 
 
 to the blade of a sickle, 'falx cerebri? It divides the 
 
 ^ cerebrum into two hemispheres a right and a left. It begins in 
 
 v a point attached to the ' crista yallij and gradually penetrates 
 
6 SINUSES OF THE DURA MATER. 
 
 deeper as it extends backwards. Its upper edge is convex and 
 attached to the median groove on the inner aspect of the vertex of 
 the skull ; its inferior margin is concave and free, and runs along 
 the upper aspect of the corpus callosum. From its base or 
 broadest part proceeds the horizontal partition named ' tentorium 
 cerebelli.' This forms an arch for the support of the 
 posterior cerebral lobes, so that they may not press 
 upon the cerebellum beneath them. Observe that the 
 tentorium is attached to the transverse ridge of the occipital bone, 
 to the superior margin of the petrous part of the temporal bone, 
 and to the posterior and anterior clinoid processes of the sphenoid. 
 The little partition which separates the lobes of the 
 eerebelli cerebellum is called f falx cerebelli.' It is placed ver- 
 tically in the same line with the falx cerebri, and its 
 point is attached to the edge of the foramen magnum. 
 SINUSES OF ^ * s one ^ the peculiarities of the cerebral circula- 
 THE DURA tion that the blood is returned through canals or 
 ' sinuses ' formed by the dura mater. These canals are 
 produced by a splitting of the dura mater into two layers as shown 
 in fig. 1, where 1 represents a vertical 
 section through the superior longitudinal Flg * L 
 
 sinus. They are lined by the same smooth 
 membrane as the rest of the venous sys- 
 tem. Since their walls consist of unyield- 
 ing structure,, and are always on the stretch, 
 it is obvious that they are admirably adapt- 
 ed to resist the pressure of the brain. 
 
 There are fifteen of these sinuses ; five are pairs, and five are single, 
 as follow : 
 
 The five pairs of sinuses are, The five single sinuses are, 
 
 The lateral. The superior longitudinal. 
 
 The superior petrosal. The inferior longitudinal. 
 
 The inferior petrosal. The circular. 
 
 The cavernous. The transverse. 
 
 The occipital. The straight. 
 
 All of these eventually discharge their blood into the internal 
 jugular veins. 
 
SUPERIOR LONGITUDINAL SINUS. 
 
 Superior Tbis runs a ^ on g tne upp er edge of the falx cerebri 
 
 longitudinal (fig. 2). It begins very small at the crista galli, 
 gradually increases in size in its course backwards, and 
 opposite the tubercle of the occipital bone divides into the right 
 and left lateral sinuses, the right 
 being in general the larger. Be- 
 sides numerous veins from the can- 
 cellous texture of the skull-cap, the 
 superior longitudinal sinus receives 
 large veins from each hemisphere 
 of the cerebrum. It is interesting 
 to observe that these veins run 
 from behind forwards, contrary to 
 the current of blood in the sinus, 
 
 , ., ., , ,. 1. Superior longitudinal sinua. 
 
 and that they paSS through the 2. Inferior longitudinal sinus. 
 
 wall of the sinus very obliquely, 
 
 J M. J > 4 } 4. Vense Galeni. 
 
 like the ureter into the bladder. 
 
 The probable object of this oblique entrance is to prevent regurgi- 
 
 tation of blood from the sinus into the veins of the brain. 
 
 Cut open the superior longitudinal sinus : observe that it is 
 triangular with its base upwards, and that its cavity is intersected 
 in many places by slender fibrous cords, termed s chordae Willisii.'* 
 Their precise use is not understood. 
 
 In the neighbourhood of the superior longitudinal 
 Pacchioni sinus we meet with small granulations, sometimes lying 
 singly, sometimes in clusters. They are termed ' glan- 
 dulce Pacchioni,'^ and are found in three distinct situations: 
 1, on the outside of the dura mater, often so large as to occasion 
 depressions in the bones ; 2, on the surface of the pia mater ; 
 3, in the interior of the longitudinal sinus, covered by its lining 
 membrane. Their size, number, and appearance differ in different 
 
 * So called after Willis, who first described them in his work De Cerebri Anatome, 
 1664. 
 
 f After the Italian anatomist, who first described them in 1705. These bodies 
 would appear to originate in the subarachnoid cellular tissue, whence they, in their 
 growth, either perforate the dura mater and hollow out the bones, or make their way 
 into the longitudinal sinus. 
 
8 SINUSES OF THE DURA MATER. 
 
 subjects. Nothing is determined concerning their precise nature ; 
 but it is presumed that they are morbid products, since they are 
 never observed in very young subjects. 
 
 The brain should now be removed, and preserved in spirit for 
 future examination. Its anatomy with that of its remaining 
 membranes will be described in a subsequent part of this work. 
 The other sinuses should now be examined. 
 
 These are the two great sinuses through which all 
 the blood from the brain is returned into the internal 
 jugular veins. Their course is well marked in the dry 
 skull. The right is commonly the larger. Each commences at 
 the internal occipital protuberance, and proceeds at first horizon- 
 tally outwards, enclosed between the layers of the tentorium, along 
 a groove in the occipital bon.e and the posterior inferior angle of 
 the parietal ; it then descends along the mastoid portion of the 
 temporal bone and again indenting the occipital, turns forwards to 
 the foramen lacerum posterius, and terminates in the internal 
 jugular vein.* 
 
 Inferior This is of small size. It runs along the inferior 
 
 longitudinal free border of the falx cerebri, and terminates in the 
 
 straight sinus at the anterior margin of the tentorium 
 
 (fig- 2). 
 
 This may be considered as the continuation of the 
 preceding. It runs along the line of junction of the 
 falx cerebri with the tentorium cerebelli, and terminates 
 at the divergence of the two lateral sinuses. It receives the two 
 ' venae Galeni ' (fig. 2), which return the blood from the lateral 
 ventricles of the brain. 
 
 This is so called because its interior is intersected by 
 
 numerous threads. It extends along the side of the 
 
 body of the sphenoid bone, outside the internal carotid 
 
 artery. It receives the ophthalmic vein which leaves the orbit 
 
 through the foramen lacerum orbitale ; and it communicates with 
 
 the circular sinus which surrounds the pituitary gland (fig. 3). 
 
 * It has in some subjects another outlet, through the foramen mastoideum, or else 
 the posterior condyloid foramen. 
 
SINUSES OF THE DUKA MATER. 
 
 Circular 
 sinus. 
 
 Petrosal 
 sinuses. 
 
 This surrounds the pituitary gland (P in the diagram), 
 and communicates on each side with the cavernous. 
 
 These lead from the cavernous to the lateral. There 
 are two on each side. The superior runs along the 
 upper edge of the petrous bone ; the inferior along the 
 suture between the petrous and the occipital bones. 
 
 Fig. 3. 
 
 Ophthalmic vein. 
 
 Third nerve . . . 
 
 Fourth nerve . . . 
 
 Sixth nerve . . . 
 
 First branch of the 
 fifth . 
 
 Superior petrosal sinus 
 
 Inferior petrosal sinus . 
 
 Carotid artery. 
 Cavernous sinus. 
 
 DIAGRAM OF THE VENOUS SINUSES AT THE BASE OF THE SKULL. 
 
 This extends from one inferior petrosal to the other, 
 across the basilar process of the occipital bone. 
 
 These are very small. They commence around the 
 margin of the foramen magnum, run in the falx 
 cerebelli, and open into the divergence of the lateral 
 sinuses.* 
 
 * The meeting of the several sinuses opposite the spine of the occipital bone is 
 
 Transverse 
 sinus. 
 
 Occipital 
 sinuses. 
 
10 EXIT OF THE CRANIAL NERVES. 
 
 The student should now proceed to examine the nerves as they 
 pass out of the base of the skull, and then to dissect the cavernous 
 sinus. 
 
 Exit of the The cranial nerves proceed in pairs through the 
 cranial foramina at the hase of the skull; they are named 
 
 nerves. first, second, third, fourth pair, &c., according to their 
 
 order of succession from before backwards. 
 
 The first pair are the olfactory nerves. These cannot be seen, 
 because the olfactory bulbs are removed with the brain, and torn 
 from the delicate filaments which pass through the cribriform plate 
 of the ethmoid bone. 
 
 The second (optic nerve) passes through the foramen opticum 
 into the orbit accompanied by the ophthalmic artery. 
 
 The third (motor oculi) passes through the dura mater, close 
 behind the anterior clinoid process, and enters the orbit through 
 the sphenoidal fissure. 
 
 The fourth (patheticus), a small nerve, passes through the dura 
 mater a little behind the posterior clinoid process. It then runs 
 forwards through the sphenoidal fissure, when it lies above the 
 third nerve, and is distributed to the superior oblique muscle. 
 
 The fifth (trigeminal nerve) passes through an aperture in the 
 dura mater beneath the tentorium cerebelli, just above the point 
 of the petrous portion of the temporal bone. Upon its larger or 
 sensitive root, is developed a great ganglion called the ' Gasserian 
 ganglion.' From this ganglion proceed the primary divisions of 
 the nerve namely, the ophthalmic, which passes through the sphe- 
 noidal fissure; the superior maxillary, through the foramen ro- 
 tundum ; and the inferior maxillary, through the foramen ovale. 
 The small motor root of the fifth lies beneath the ganglion, with 
 which it has no communication, and accompanies the inferior 
 maxillary division to supply the muscles of mastication. 
 
 The sixth (abducens) passes through the dura mater behind the 
 
 termed the ' torcular Herophili,' after the celebrated anatomist who first described it. 
 
 It is a kind of triangular reservoir, with the base below, and presents six openings 
 
 namely, that of the superior longitudinal sinus, those of the two lateral and of the two 
 occipital, and that of the straight sinus. The term 'torcular' is an incorrect ver- 
 sion of the original word <r<a\^v (a canal or gutter), employed by Herophilus. 
 
EXIT OF THE CRANIAL NERVES, 
 
 11 
 
 body of the sphenoid, which it grooves. It enters the orbit through 
 the sphenoidal fissure, and supplies the external rectus. 
 
 Olfactory bulb 
 
 Optic nerve . 
 Third nerve . 
 
 Fourth nerve . 
 Fifth nerve . 
 
 Sixth nerve . 
 Seventh nerve 
 
 Ninth nerve . 
 Eighth nerve 
 
 Fig. 
 
 EXIT OF THE CRANIAL NERVES. 
 
 The seventh, consisting of the faded and auditory nerves, passes 
 through the meatus auditorius internus, in which they are con- 
 
12 CAVERNOUS SINUS. 
 
 nected by small offsets. The facial nerve lies internal to and 
 above the auditory, before it enters the meatus auditorius. 
 
 The eighth, consisting of the glosso-pharyngeal^pneiimogastric^ 
 and spinal accessory, passes through the anterior part of the 
 foramen jugulare. These three divisions do not all pass through 
 the same tube of dura mater. The glosso-pharyngeal has a 
 separate tube anterior to the other two, which have a common 
 one. 
 
 The ninth, or hypoglossal nerve, passes through the anterior 
 condyloid foramen in two fasciculi, which unite external to the 
 skull. 
 
 We must now examine the cavernous sinus, and the nerves 
 which course through its walls to the orbit namely, the third, 
 the fourth, the first division of the fifth, and the sixth. 
 
 Cavernous Tnis s ^ nus (% 3 ) ^ ies ^7 the S ^ e f tbe kdy of 
 
 sinus. the sphenoid bone. In front it receives the ophthalmic 
 
 vein, which comes through the sphenoidal fissure ; behind, the 
 superior and inferior petrosal sinuses run out of it ; on the inner 
 side it communicates with the circular sinus which surrounds the 
 pituitary gland (P in the diagram). 
 
 In the outer wall of the cavernous sinus we trace from above 
 downwards the third nerve, the fourth, the first division of the 
 fifth, on their course to the orbit.* On its inner wall are situated 
 the sixth nerve, and the internal carotid artery. These objects are 
 said to be contained in the cavernous sinus ; but they are not 
 bathed by the blood of the sinus, because they are separated from 
 it by the lining membrane. 
 
 After the removal of the cavernous sinus, a good 
 the carotid view is obtained of the remarkable curves, like the 
 artery. letter S, made by the carotid artery by the side of the 
 
 sella turcica. The vessel enters the cranium at the apex of the 
 petrous portion of the temporal bone, makes its sigmoid curves, 
 and then passes through the dura mater, between the anterior 
 clinoid process and the optic nerve ; here it gives off the ophthalmic 
 
 * Such is the order in which the nerves are placed in the wall of the sinus. As 
 they enter the orbit, the fourth nerve crosses over the third. 
 
THE DISSECTION OF THE NECK. 13 
 
 artery. While in the cavernous sinus, small branches (arteriae 
 receptaculi) arise from the carotid and supply the pituitary body, 
 and the walls of the cavernous sinus. 
 
 Cavernous The superior cervical ganglion of the sympathetic 
 
 plexus. sends up with the carotid artery filaments, which form 
 
 a plexus round it in its tortuous course through the carotid canal, 
 and by the side of the sphenoid. After a careful dissection you 
 may discover with the naked eye in this plexus, very small ganglia 
 called carotid or cavernous ; but they vary in number, size, and 
 situation. Through these nerves a communication is established 
 between the sympathetic and the nerves which enter the orbit. 
 
 THE DISSECTION OF THE NECK. 
 
 Make an incision through the skin, down the middle of the neck 
 from the jaw to the sternum ; a second along the clavicle to the 
 acromion ; a third along the base of the jaw as far as the mastoid 
 process. Reflect the skin, and expose the cutaneous muscle called 
 the ( platysma myoides.'' Between the platysma and the skin is a 
 layer of adipose tissue, called the 'superficial fascia.' It varies in 
 thickness in different subjects, but is generally more abundant at 
 the upper part of the neck, especially in corpulent individuals, in 
 whom it occasions a double chin. 
 
 The platysm.a 'myoides is the cutaneous muscle of 
 ^ e nec ^' -^ arises from the subcutaneous tissue over 
 the pectoralis major and deltoid muscles ; thence pro- 
 ceeding over the clavicle and the side of the neck, its fibres 
 become more closely aggregated, and terminate thus: The 
 anterior cross those of the opposite platysma, immediately below 
 the symphysis of the jaw, and are lost in the skin of the chin ; the 
 middle are attached along the base of the jaw ; the posterior cross 
 the masseter muscle, and terminate partly in the subcutaneous 
 tissue of the cheek, partly in the muscles at the corner of the 
 mouth. 
 
14 EXTERNAL JUGULAR VE1X. 
 
 The platysma forms a strong muscular defence for the neck. 
 It is also a muscle of expression.* It is supplied with nerves by 
 the cervical plexus, and by the cervical branch of the facial nerve. 
 
 Cut through the platysma near the clavicle and turn it upwards. 
 Beneath it lies the general investment of the neck, called the 
 s deep cervical fascia.' Upon this fascia, we trace the superficial 
 branches of the cervical plexus of nerves, the external jugular vein, 
 and a smaller vein in front, called the anterior jugular. These 
 superficial veins are so variable in size and course, that a general 
 description only is applicable. 
 
 External ^ e ex t erna l jugular vein is formed within the sub- 
 
 jugular stance of the parotid gland by the junction of the 
 temporal and internal maxillary veins. After receiving 
 the transverse facial and posterior auricular veins, it appears at 
 the lower border of the gland, crosses obliquely over the sterno- 
 mastoid muscle (Fig. 5), to its posterior border, nearly as low 
 down as the clavicle, where it pierces the deep cervical fascia and 
 terminates in the subclavian vein. It is usually provided with two 
 pairs of valves. A line drawn from the angle of the jaw to the 
 middle of the clavicle would indicate its course. To trace the 
 vein, during life, press upon it just above the clavicle; but do not 
 be surprised if you fail to find it ; it is sometimes wanting. 
 
 Near the angle of the jaw the external jugular vein communi- 
 cates by a large branch with the internal jugular. 
 
 * If the entire muscle be permanently contracted it may occasion wry-neck, though 
 distortion from such a cause is an exceedingly rare occurrence. A case in point is 
 related by Mr. Gooch (Chirurg. Works}, in which a complete cure was effected, after 
 the failure of all ordinary means of relief, by the division of the platysma a little below 
 the jaw. 
 
 The platysma myoides belongs to a class of muscles called ' cutaneous, from their 
 office of moving the skin. There are not many in man, except upon the neck and face, 
 and there is a little one (palmaris brevis) in the palm of the hand. To understand 
 their use thoroughly we must refer to the lower orders of animals, in whom they fulfil 
 very important functions, by moving not only the skin, but also its appendages. For 
 instance, by muscles of this kind the hedgehog, porcupine, and animals of that family 
 can roll themselves up and erect their quills: we are all familiar with the broad ' pan- 
 niculus carnosus ' on the sides of herbivorous quadrupeds, which enables them to 
 twitch their skins, and thus rid themselves from insects. In birds, too, these cutaneous 
 muscles are extremely numerous, each feather having appropriate muscles to move it. 
 
ANTERIOR JUGULAR VEIN. 
 
 15 
 
 Before its termination the external jugular vein generally re- 
 ceives the supra-scapular, posterior scapular, and other unnamed 
 veins: a disposition very unfavourable for the surgeon, because 
 there is a confluence of veins immediately over the subclavian 
 artery in the place where it is usually tied. 
 
 Fig. 5. 
 
 Cervical branch of 
 facial n. . . . 
 
 N. superficialis 
 colli . . . 
 
 External jugu- 
 lar v. . . . 
 
 Anterior jugu- 
 lar v. ... 
 
 Small occipital 
 
 Auriculo-paro- 
 tidean n. 
 
 Nervus acces- 
 sorius. 
 
 Descending 
 branch of cer- 
 vical plexus. 
 
 Anterior 
 
 jugular 
 
 rein. 
 
 DIAGRAM OF THE SUPERFICIAL NERVES AND VEINS OF THE NECK. 
 
 The anterior jugular vein is situated more in the 
 middle of the neck, and is much smaller than the exter- 
 nal jugular. It commences by small branches below the 
 chin, and runs down the front of the neck, nearly to the sternum : 
 it then curves outwards, beneath the sterno-mastoid muscle, and 
 opens either into the external jugular or the subclavian vein. We 
 commonly meet with two anterior jugular veins, one on either 
 side ; immediately above the sternum they communicate by a 
 transverse branch. 
 
 The size of the anterior jugular vein is inversely proportionate 
 to that of the external jugular. When the external jugular is 
 small, or terminates in the internal jugular, then the anterior 
 
16 CUTANEOUS NERVES OF THE NECK. 
 
 jugular becomes an important supplemental vein,^nd attains con- 
 siderable size. It is not uncommon to find it a quarter of an inch 
 in diameter, and we have seen it nearly half an inch. These 
 varieties should be remembered in tracheotomy. 
 
 Superficial absorbent glands are sometimes found near the 
 cutaneous veins of the neck. They are small, and escape observa- 
 tion unless enlarged by disease. One or two are situated over the 
 sterno-mastoid muscle ; others near the mesial line. 
 
 The cutaneous nerves of the neck are the superficial 
 
 Cutaneous -, -, 
 
 nerves of branches of the cervical plexus : the plexus itself cannot 
 at present be seen. It lies under the sterno-mastoid 
 muscle, close to the transverse processes of the four upper cervical 
 vertebrae, and is formed by the communications of the anterior 
 divisions of the four upper cervical nerves. The cutaneous branches 
 of the plexus emerge beneath the posterior border of the sterno- 
 mastoid, and take different directions. We divide and name them 
 thus (fig. 5): 
 
 (Ascending branches ( Auriculo-parotidean. 
 
 \ Small occipital. 
 
 Cutaneous branches of I Transverse branch Superficialis colli. 
 
 the cervical plexus. "^ I Sternal. 
 
 Descending branches -I Clavicular. 
 
 (Acromial. 
 
 The auriculo-parotidean n. cornes from the second and third 
 cervical nerves, and ascends obliquely over the sterno-mastoid 
 muscle, near the external jugular vein, towards the parotid gland. 
 Near the gland it divides into two principal branches, of which 
 the anterior is distributed to the skin over the gland and the side 
 of the cheek ; the posterior ascends to the cartilage of the ear, 
 and ramifies chiefly upon its occipital surface. Other filaments 
 communicate in the substance of the parotid gland with branches 
 of the portio dura, or facial nerve. 
 
 The small occipital nerve comes from the second cervical nerve. 
 It runs near the posterior border of the sterno-mastoid muscle to 
 the occiput, where it supplies the back of the scalp. It also sends 
 off a branch which is distributed to the skin of the side of the 
 head. Beneath the sterno-mastoid this nerve commonly forms a 
 
CERVICAL FASCIA. 17 
 
 loop which embraces the nervus accessorius, and sends a branch 
 to it. 
 
 The transverse branch, called the n. superficialis colli, comes 
 from the second and third cervical nerves. It passes forwards over 
 the sterno-mastoid muscle, and supplies the front of the neck. 
 Some of its filaments ascend towards the jaw, and join the cer- 
 vical branch of the facial nerve ; other filaments descend and sup- 
 ply the skin in front of the neck as low as the sternum. 
 
 The descending branches are derived from the third and fourth 
 cervical nerves, and divide into three branches, which cross over 
 the clavicle, and supply the skin of the front of the chest and 
 shoulder. Of these, one, called the sternal, supplies the skin over 
 the upper part of the sternum; another, the clavicular, passes 
 over the middle of the clavicle, and is distributed to the skin over 
 the pectoral muscle, the mammary gland, and the nipple ; the 
 third, named acromial, crosses over the acromion to supply the 
 skin of the shoulder. Keviewing these cutaneous branches of the 
 cervical plexus, we find that they have a very wide distribution, 
 for they supply the skin covering the following parts viz., the 
 ear, the back of the scalp, the side of the cheek, the parotid gland, 
 the front and side of the neck, the upper and front part of the 
 chest and shoulder. 
 
 Look for this branch beneath the fascia near the 
 
 brand? of angle of the jaw (p, 15). It leaves the parotid gland, 
 
 the facial and divides into filaments which curve forwards below 
 
 the jaw ; some of these join the transverse branch of 
 
 the cervical plexus ; others supply the platysma. 
 
 Now turn your attention to the membranous invest- 
 fascia!* ment called the ' cervical fascia,' which encloses the se- 
 veral structures of the neck. In some subjects the fascia 
 is very thin; in others, with strong muscles, it is proportionably 
 dense and resisting. It is always relatively stronger in particular 
 situations, for the more effective protection of the parts beneath ; 
 for instance, in front of the trachea, in the fossa above the clavicle, 
 and below the angle of the jaw. It not only covers the soft parts 
 of the neck collectively, but, by its inflections, forms separate 
 
 c 
 
18 CEKVJCAL FASCIA. 
 
 sheaths for the muscles, vessels, and glands. It isolates them, and 
 keeps them in their proper relative position. A lengthened 
 description of its numerous layers would be not only extremely 
 tedious, but unintelligible, without considerable knowledge of the 
 anatomy of the neck. We propose, therefore, to give only a 
 general outline of the fascia, and of its principal layers, com- 
 mencing from behind. 
 
 Tracing it from behind, we find that the cervical fascia (some- 
 times called deep cervical or muscular fascia of the neck) is 
 attached to the ligamentum nuchaB and to the spinous and trans- 
 verse processes of the cervical vertebra?. From these attachments 
 it passes forwards to the posterior border of the sterno-mastoid, 
 where it splits into two layers, which invest that muscle and re- 
 unite at its anterior border. It then passes towards the mesial 
 line, where it becomes continuous with the corresponding fascia of 
 the opposite side. The layer which lies in front of the sterno- 
 mastoid is attached above to the base of the inferior maxilla, to 
 the zygoma, to the mastoid process, and the superior curved line of 
 the occipital bone. Traced downwards, we find it attached to the 
 clavicle and to the upper border of the sternum. In the middle 
 line it is closely connected to the hyoid bone, and below the thyroid 
 body divides into two layers, one being attached to the front of the 
 upper border of the sternum, the other to the back of the upper 
 border of the same bone. Between these layers there is a well- 
 marked interval, in which are contained more or less fat, and one 
 or two small absorbent glands. This layer forms investing sheaths 
 for the depressor muscles of the os hyoides and larynx. The other 
 layer viz., that which passes beneath the sterno-mastoid forms 
 the common sheath for the carotid artery, internal jugular vein, 
 and the pneumo-gastric nerve, which lie behind this muscle ; it 
 proceeds inwards as a thin layer, and is continued behind the 
 pharynx (constituting the prctvertebral fascia) to join the fascia of 
 the opposite side. Below, it is attached to the first rib, to which it 
 binds down the intermediate tendon of the omo-hyoid ; and still 
 further down it is continuous with the external coat of the aorta 
 and the pericardium. It may, also, be traced under the clavicle 
 
CERVICAL FASCIA. 19 
 
 along the axillary vessels and nerves into the axilla. Above it is 
 attached to the angle of the lower jaw, from which it extends 
 backwards to the styloid process, and forms the 'stylo-maxillary' 
 ligament. Thence it is attached to the base of the skull, the 
 petrous portion of the temporal bone, and the basilar process of the 
 occipital bone. 
 
 A correct knowledge of the attachments of the principal layers 
 of the cervical fascia is essential to a right understanding of the 
 course which pus takes when it forms in the neck. For instance, 
 suppose the pus to be formed at the lower part of the neck. 
 If it be seated immediately under the superficial layer (which is 
 attached to the clavicle), it may burrow beneath the clavicle into 
 the axilla. But if it be seated beneath the deep layer (which is 
 attached to the first rib), then it becomes a more serious affair, 
 since the pus may readily travel through the loose tissue by the 
 side of the pharynx, and make its way into the chest, where it will 
 probably burrow down the anterior or the posterior mediastinum, 
 and burst into the trachea or the oesophagus. 
 
 Besides forming sheaths for the several structures of the neck, 
 there are other purposes to which the cervical fascia is subservient. 
 The firm attachment of its layers to the sternum, the first rib, and 
 the clavicle, forms a fibrous barrier at the upper opening of the 
 chest, which supports the soft parts, and prevents their yielding 
 to the pressure of the atmosphere during inspiration. Dr. Allan 
 Burns* first pointed out this important function of the cervical 
 fascia, and has recorded a case exemplifying the results of its de- 
 struction by disease. 
 
 Moreover, the great veins at the root of the neck, namely, the 
 internal jugular, subclavian, and innominate, are so closely united 
 by the cervical fascia to the adjacent bones and muscles, that 
 when divided they gape. They are, as the French express it, 
 ( canalisees,' and are therefore better able to resist the pressure of 
 the atmosphere, which tends to render them flaccid and imper- 
 vious during inspiration. But this anatomical disposition of the 
 
 * Surgical Anatomy of the Head and Neck. 
 c 2 
 
20 STERNOCLEIDOMASTOIDEUS. 
 
 great veins makes them more liable to the entrance ^of air when 
 wounded. Many deaths are recorded, resulting from the sudden 
 entrance of air into the veins during operations about the neck, 
 or even the axilla. 
 
 The sterno-cleido-mastoideus arises by a round 
 cleido-mas- tendon from the upper part of the sternum, and by 
 toideus. fleghy fibres ^ from the s ternal third of the clavicle. It 
 is inserted by a thin aponeurosis into the mastoid process, and 
 about the outer half of the superior curved ridge of the occipital 
 bone. 
 
 The sternal origin of the muscle is at first separated from the 
 clavicular by a slight interval: subsequently the sternal fibres 
 gradually overlap the clavicular. The muscle is confined by its 
 strong sheath of fascia, in such a manner that it forms a slight 
 curve, with the convexity forwards. Observe especially that its 
 front border overlaps the common carotid artery; along this border 
 we make the incision in the operation of tying the -vessel. 
 Action f When both sterno-mastoidei act simultaneously, they 
 
 stemo- draw the head and neck forwards, and are therefore 
 
 mastoid. especially concerned in raising the head from the re- 
 cumbent position. When one sterno-mastoid acts singly, it turns 
 the head obliquely towards the opposite shoulder ; in this action it 
 co-operates with the splenins of the other side.* On emergency, 
 the sterno-mastoid acts as a muscle of inspiration, by raising the 
 sternum, its fixed point being, in this case, at the head. The 
 sterno-mastoid is supplied with nerves by the n. accessorius, and 
 by deep branches of the cervical plexus. It has three nutrient 
 arteries, an upper mastoid, a middle, and a lower. 
 
 The upper mastoid artery, a branch of the occipital, enters the 
 muscle with the n. accessorius ; the middle mastoid is a branch 
 
 * The single action of the muscle is well seen when it becomes rigid . and causes a 
 wry neck. Other means of relief failing, the division of the muscle near its origin is 
 sometimes beneficial in curing the distortion. In deciding as to the propriety of this 
 operation, we should be careful to examine the condition of the other muscles, lest, 
 after having divided the sterno-mastoid, we should be disappointed in removing the 
 deformity. 
 
TRIANGLES OF THE NECK. 21 
 
 of the superior thyroid; the lower mastoid is a branch of the 
 supra-scapular. 
 
 Anatomists avail themselves of the sterno-mastoid 
 f musc ^ e 5 to divide the neck on each side into two great 
 
 triangles, an anterior and a posterior (fig. 6). The base 
 of the anterior triangle is formed by the jaw, its sides by the 
 mesial line and the front border of the sterno-mastoid. The pos- 
 terior has the clavicle for the base, while the sides are defined by 
 the hind border of the sterno-mastoid, and the free border of the 
 trapezius. 
 
 The omo-hyoid muscle, which crosses the neck under the sterno- 
 mastoid, subdivides these great primary triangles into four smaller 
 ones (fig. 6), of unequal size : an anterior superior, an anterior 
 inferior, a posterior superior, and a posterior inferior. The direc- 
 tion of the omo-hyoid muscle renders their boundaries at once 
 obvious. 
 
 Contents of ^e ^ anc ^ ce ^ u l ar tissue must now be carefully 
 posterior removed from the posterior triangle. The following 
 
 muscles will be seen forming its floor, viz., beginning 
 from above, the splenius capitis, the levator anguli scapulae, the 
 scalenus medius and posticus. This triangle is subdivided into 
 two unequal parts by the posterior belly of the omo-hyoid an 
 upper or occipital and a lower or clavicular. In the upper tri- 
 angle are found the superficial branches of the cervical plexus, and 
 passing obliquely downwards from beneath the sterno-mastoid is 
 the spinal accessory nerve, which enters the under part of the 
 trapezius. The transversalis colli (posterior scapular) artery and 
 vein, and its branch the superficialis colli (which chiefly supplies 
 the trapezius), cross transversely outwards the lower part of the 
 space. A chain of lymphatic glands is also found along the pos- 
 terior border of the sterno-mastoid. 
 
 The upper part of the sterno-mastoid is traversed 
 
 obliquely by a large nerve called the spinal accessory or 
 
 n. accessorius. This nerve, one of the three divisions of 
 the eighth pair of cerebral nerves, arises from the cervical portion 
 of the spinal cord by a series of filaments from the lateral tract as 
 
22 
 
 NERVUS ACCESSORIUS. 
 
 low down as the sixth cervical vertebra. It ascends Jbetween the 
 ligamentum denticulatum and the posterior roots of the spinal 
 nerves, through the foramen magnum into the skull. It leaves 
 the skull through the foramen lacerum posterius, runs behind the 
 internal jugular vein, then passes obliquely through the upper 
 third of the sterno-inastoid, and crosses the posterior triangle of 
 
 Fig. 6. 
 
 N. accessorius . . 
 
 Digastricus . . . 
 Os-hyoides . . . 
 
 Omo-hyoideus . . 
 
 Sterno-mastoid 
 muscle drawn aside. 
 
 Splenius capitia 
 
 Levator anguli sca- 
 pulas. 
 
 - Scalenus medius. 
 
 Scalenus anticus. 
 
 TRIANGLES OF THE NECK. 
 
 the neck to the under surface of the trapezius, to which it is dis- 
 tributed. The nervus accessorius supplies also the sterno-mastoid, 
 and, after leaving the muscle, is joined by branches from the 
 second and third cervical nerves. The upper mastoid artery, a 
 branch of the occipital, runs into the sterno-mastoid with the 
 nerve. 
 
 Supra- The supra-clavicular triangle is bounded below by the 
 
 clavicular clavicle, in front by the outer border of the sterno-mas- 
 toid, and above by the posterior portion of the omo- 
 hyoid muscle. The area of the triangle thus formed will vary in 
 proportion to the obliquity of the omo-hyoid muscle, and the extent 
 to which the sterno-mastoid is attached to the clavicle ; the trape- 
 zius must also be taken into the account, for in some instances it 
 
SUPRA-CLAVICULAR TRIANGLE. 23 
 
 comes so far forwards as almost to meet the sterno-mastoid. The 
 depth of the vessels and nerves contained in this space depends 
 not only upon the degree to which the clavicle arches forwards, 
 but varies with the elevation and depression of the shoulder. 
 
 Immediately beneath the skin covering this region we find the 
 platysma myoides, the descending branches of the cervical plexus, 
 and a layer of fascia which binds down the omo-hyoid muscle to 
 the clavicle. Beneath this is a deeper layer of fascia, which covers 
 the subclavian vessels and the brachial plexus of nerves, and 
 descends with them beneath the clavicle into the axilla. Between 
 these two layers we meet with more or less fat and areolar tissue, 
 and absorbent glands continuous with those in the axilla. It will 
 be easily understood how a collection of matter, originating in the 
 axilla, may ascend in front of the vessels and point above the 
 clavicle, or, vice versa, matter formed in the neck may travel 
 under the clavicle and point in the axilla. 
 
 Near the posterior border of the sterno-mastoid muscle the 
 external jugular vein passes through both layers of the fascia, and 
 terminates in the subclavian : but before its termination it is 
 commonly joined by the supra-scapular, the posterior scapular, 
 and other unnamed veins proceeding from the surrounding 
 muscles ; so that we have in this particular situation a confluence 
 of veins, which, when large or distended, are exceedingly em- 
 barrassing. 
 
 The fascia and the glands should be removed, and the fol- 
 lowing objects carefully dissected. Behind and nearly parallel 
 with the clavicle is the supra-scapular (transversalis humeri) 
 artery, a branch of the thyroid axis. A little higher is the trans- 
 versalis colli, or posterior scapular (commonly a branch of the 
 thyroid axis), which crosses the lower part of the neck towards 
 the posterior superior angle of the scapula. Both these arteries, 
 the last particularly, are very irregular in respect to their origin. 
 Search for the outer border of the scalenus anticus, which de- 
 scends from the transverse processes of the cerebral vertebrae to 
 the first rib : running down perpendicularly upon it is seen the 
 phrenic nerve. The subclavian vein lies upon the first rib in front 
 
24 DEPKESSOKS OF THE OS-HYOIDES. 
 
 of the insertion of the muscle. The subclavian artery, which 
 appears behind the outer border of the scalenus anticus, must be 
 fairly exposed, care being taken to preserve the small branch 
 which proceeds from the brachial plexus to the subclavius muscle. 
 The large nerves constituting the brachial plexus will be found 
 emerging between the scalenus anticus and medius, higher than 
 the subclavian artery. 
 
 The anterior triangle must now be dissected. And 
 triangle 1 " ^ rst examine the flat muscles in front of the neck, 
 
 which pull down the larynx ; namely, the sterno-hyoid, 
 sterno-thyroid, and omo-hyoid.* Remove the fascia which covers 
 them, disturbing them as little as possible, and take care of the 
 nerves (branches of the descendens noni), which enter their outer 
 borders. 
 
 The sterno-hyoid arises from the back part of the 
 
 sternum and sterno-clavicular ligament, and is inserted 
 
 into the lower border of the body of the os-hyoides. 
 This is the most superficial of the muscles in front of the neck. 
 We cut in the mesial line between these muscles in laryngotorny. 
 
 The sterno-thyroid arises from the back part of the 
 thyroid. sternum, below the origin of the sterno-hyoid and the 
 
 cartilage of the first rib, and is inserted into the oblique 
 ridge on the ala of the thyroid cartilage. This muscle is situated 
 immediately under, and is much broader than, the sterno-hyoid. 
 
 Notice that the two sterno-hyoid muscles converge as they 
 ascend to their insertions, and that opposite the cricoid cartilage 
 and the two or three upper rings of the trachea they are in contact 
 with one another. The sterno-thyroid, however, diverge to their 
 insertions and are in contact below, the result of which is that the 
 trachea is completely covered in front by muscular fibres. 
 Om h - id ^^ e om -hyid arises from the upper border of the 
 
 scapula, and from the ligament over the notch, and is 
 
 * The sterno-hyoid and sterno-thyroid muscles often present slight transverse 
 tendinous lines. These tendinous intersections are quite rudimentary in man ; but in 
 some animals with long necks, e. g. the giraffe, they are so developed that each de- 
 j'Tessor muscle is composed of alternations of muscle and tendon. 
 
DEPKESSORS OF THE OS-HYOIDES. 
 
 25 
 
 inserted into the body of the os-hyoides near the great cornu. 
 This muscle is digastric ; that is, it consists of two fleshy portions 
 connected by a tendon. From the scapula it comes nearly hori- 
 
 Fie. 7. 
 
 Occipital a. . 
 
 Hypoglossal n. 
 Descendens 
 noni 11. . . 
 
 2nd cervical n. 
 Superior thy- 
 roid a. . . 
 
 3rd cervical n. . 
 Communicans 
 noni n. . . . 
 
 Crico-thyroid m, 
 Internal jugu- 
 lar v. . . . 
 Common caro- 
 tid a. . . . 
 
 Digastricns. 
 
 Junction of my- 
 lo-hyoidei. 
 
 . accessorius. 
 
 Os-hyoides. 
 
 Pomum Adami. 
 
 Cricoid cartilage. 
 
 Isthmus of thy- 
 roid gland. 
 
 Trachea. 
 
 Inferior thy- 
 roid v. 
 
 CENTRAL LINE OF THE NECK. COURSE AND RELATIONS OF COMMON CAROTID A. 
 
 zontally forwards across the lower part of the neck, and passes 
 beneath the sterno-mastoid, over the sheath of the great vessels of 
 the neck; then, changing its direction, it ascends nearly vertically 
 close to the outer border of the sterno-hyoid. Thus the muscle 
 
26 DEPRESSORS OF THE OS-HYOIDES. 
 
 does not proceed straight from origin to insertion, fyut forms an 
 obtuse angle beneath the sterno-mastoid muscle. The inter- 
 mediate tendon is situated at the angle, and is bound down to the 
 first rib by a process of the deep cervical fascia. The object of 
 this peculiar direction of the omo-hyoid appears to be to keep 
 tense that part of the cervical fascia which covers the apex of the 
 lung, and thus to resist atmospheric pressure. 
 
 The sterno-hyoid, sterno-thyroid, and omo-hyoid 
 of the de- muscles, co-operate in fixing the larynx and os-hyoides, 
 pressop 6j p. in sucking", or they depress the larynx after it has 
 
 muscles. . *' / r J 
 
 been raised in deglutition. Again, they depress it in the 
 utterance of grave notes. That the larynx is raised or depressed 
 according to the height of the note may be ascertained by placing 
 the finger upon it while we go through the gamut. 
 
 These depressor muscles are all supplied with nerves (fig. 7, 
 p. 25) by the 6 descendens noni ' (a branch of the ninth, or hypo- 
 glossal), and by the 6 communicantes noni ' (branches of the cervical 
 plexus). The descendens noni sends a separate branch to each 
 belly of the omo-hyoid. They are supplied with blood by the 
 superior thyroid artery. 
 
 The thyro-hyoid arises from the oblique line on the 
 hyoid" a ^ a f tDe thyroid cartilage, and runs up to be inserted 
 
 into the body and half the great cornu of the os- 
 hyoides. This muscle is a continuation of the sterno-thyroid. It 
 is supplied by a special branch from the hypoglossal nerve. It 
 covers the thyro-hyoid membrane, and the superior laryngeal 
 nerve and artery as they enter the larynx. 
 
 The sterno-mastoid muscle must now be reflected from its origin 
 to examine the course and relations of the common carotid artery. 
 This done, notice the strong layer of fascia which lies under the 
 sterno-mastoid, and forms the under part of its sheath. It is at- 
 tached to the angle of the jaw, thence descends over and protects 
 the great vessels of the neck, and is firmly connected to the 
 clavicle and first rib. This fascia prevents matter from coming 
 to the surface, when suppuration takes place by the side of the 
 pharynx. 
 
COMMON CAROTID ARTERY. 27 
 
 Remove this fascia, taking care not to cut away the descendens 
 noni and communicantes noni nerves, which cross the sheath of 
 the common carotid. Dissect out any absorbent glands which lie 
 about the sheath of the great vessels. 
 
 The common carotid arises on the right side from the 
 
 Course and. 
 
 relations of artena innommata behind the right sterno-clavicular 
 the common articulation ; on the left, from the arch of the aorta. 
 
 carotid. 
 
 It ascends in front of the bodies of the cervical ver- 
 tebraB, by the side of the trachea, thyroid gland, and larynx, as 
 high as the upper border of the thyroid cartilage, and then divides 
 into the external and internal carotid. Thus a line drawn from 
 the sternal end of the clavicle to a point midway between the 
 mastoid process and the angle of the jaw, will nearly indicate its 
 course. It is contained in a sheath of cervical fascia. In the 
 same sheath are the internal jugular vein and the pneumogastric 
 nerve. The vein lies on the outer side of, and parallel with, the 
 artery : the nerve lies behind, and between the artery and the 
 vein. Behind the sheath is the sympathetic nerve. Lastly, along 
 the vertebral column the sheath lies successively upon the longus 
 colli and the rectus capitis anticus major muscles. 
 
 At the lower part of the neck the carotid artery is deeply seated ; 
 it is covered by the superficial fascia, platysma myoides, deep 
 fascia, the sternal portion of the sterno- mastoid, the sterno-hyoid, 
 and thyroid muscles, and about two inches above the clavicle it is 
 crossed by the omo-hyoid. Above this point the artery becomes 
 more supevficial, and is covered by the platysma, cervical fasciae, 
 and only slightly overlapped by the sterno-mastoid. Lying im- 
 mediately upon the sheath of the artery, we find the descendens 
 noni joined by the communicantes noni nerves. The sheath is 
 crossed by three veins ; namely, the facial, the superior, and middle 
 thyroid- veins, which empty themselves into the internal jugular. 
 This is the general rule, and especial attention should be directed 
 to it, because the veins are liable to be overlooked and injured in 
 the operation of tying the carotid. 
 
 It is plain that it is easier to tie the common carotid above the 
 omo-hyoid than below it. We make an incision (three inches long) 
 
28 INTERNAL JUGULAR VEIN. 
 
 down the inner border of the sterno-mastoid ; we cutvthrough the 
 platysma and cervical fascia, draw aside the overlapping edge of 
 the sterno-mastoid, and expose the sheath of the vessel. We then 
 make a small opening in the sheath large enough to admit the 
 aneurismal needle, and tie the vessel, taking care not to include 
 the pneumogastric or descendens noni nerves in the ligature. 
 In what I n the first part of its course the left carotid differs 
 
 respects the from the right in the following particulars : 
 
 left carotid Tl ,, ,. , ,. ,, . .-, c 
 
 differs from ! It arises from the arch of the aorta, is therefore 
 the right. longer and deeper seated than the right, and is covered 
 by the first bone of the sternum. 
 
 2. It is crossed by the left brachio-cephalic vein. 
 
 3. It is in close relation with the oesophagus. 
 
 4. It is in close relation with the left recurrent nerve. 
 
 5. It is in close relation with the thoracic duct. 
 
 The common carotid at its division is often a little 
 of the bulbous. This dilatation is sometimes so marked, that 
 
 common during life we have seen it mistaken for an incipient 
 
 carotid. _, . , ., ,. ,. , 
 
 aneurism. It is necessary to be aware that the carotid 
 sometimes divides much lower than usual. Several times we have 
 seen the division as low as the level of the cricoid cartilage. 
 Internal ^e i n ^ erna ^ jugular vein returns the blood from the 
 
 jugular brain. Leaving the skull at the foramen jugulare, the 
 vein. ye j n (j e g ceric i s on the outer side of the carotid, but in 
 
 the sheath with it, and joins the subclavian vein at nearly a right 
 angle to form the brachio-cephalic. In its course down the neck 
 it receives the pharyngeal, occipital, lingual, facial, superior and 
 middle thyroid veins. 
 
 Previous to its termination the internal jugular advances slightly 
 to meet the subclavian vein, so that it lies on a plane a little ante- 
 rior to the carotid. Besides which, the direction of the vein being 
 perpendicular, and that of the artery oblique, there is necessarily a 
 small interval between them at the lower part of the neck, more 
 especially on the right side. In this interval we find the pneumo- 
 gastric nerve, and, deeper, the vertebral artery. Here, too, on the 
 left side, we look for the thoracic duct. 
 
THYROID BODY. 29 
 
 The descendens noni (p. 25), a branch of the hypo- 
 glossal, runs down obliquely over the sheath of the car- 
 Descendens o ^ ^ SU pply the depressor muscles of the os-hyoides. 
 Trace the nerve upwards, and see that it leaves the 
 hypoglossal where this nerve curves round the occipital, or perhaps 
 the mastoid artery. For a short distance the descendens noni lies 
 within the carotid sheath ; but about the level of the os-hyoides it 
 comes through the sheath, and crosses obliquely the carotid, from 
 the outer to the inner side. The descendens noni is reinforced by 
 one or more nerves termed communicantes noni (derived from the 
 second and third cervical nerves). These communicating branches 
 descend on the outer side of the internal jugular vein, and form 
 generally two loops in front of the carotid sheath. From these 
 loops the nerves proceed to the anterior and posterior bellies of 
 the omo-hyoid, the sterno-hyoid, and sterno-thyroid muscles. A 
 small branch may sometimes be traced proceeding from the descen- 
 dens noni into the chest to join the cardiac and phrenic nerves. 
 
 In some subjects the descendens noni seems to be wanting ; but 
 look carefully, and you will probably discover it concealed within 
 the carotid sheath : in such case the reinforcing loops from the 
 cervical nerves will be found behind the internal jugular vein. 
 
 Let us now examine the thyroid body, and, to expose it, let us 
 reflect the sterno-hyoid and thyroid muscles from their insertions 
 so that they can be replaced if necessary. Afterwards we will ex- 
 amine the absorbent glands of the neck, and then survey the 
 objects in the central line of the neck, from the jaw to the 
 sternum. 
 
 This very vascular gland-like substance lies over the 
 front and sides of the upper part of the trachea, and 
 extends upwards on each side of the larynx. It con- 
 sists of two lateral lobes, connected a little below the cricoid carti- 
 lage by a transverse portion called the ' isthmus.' Each lobe is 
 conical, about two inches in length, with the base opposite the 
 sixth or seventh ring of the trachea, and the apex by the side of 
 the thyroid cartilage. Its anterior surface is covered by the 
 sterno-hyoid, sterno-thyroid, and omo-hyoid muscles ; its deep 
 
30 THYROID BODY. 
 
 surface clasps the sides of the trachea and larynx, and, usually ex- 
 tends so far backwards as to be in contact with the pharynx. Its 
 external border overlaps, in most cases partially, but sometimes 
 completely, the common carotid artery, particularly on the right 
 side ; and there are instances in which the lobe is deeply grooved 
 by the vessel. 
 
 The isthmus lies over the second and third rings of the trachea. 
 This portion of the organ varies much in its dimensions. In some 
 instances there is no transverse portion. This corresponds with the 
 normal disposition in most of the lower orders of mammalia ; but 
 in man, it is a failure in the union of the two halves by which the 
 organ is originally developed.* Generally, the vertical measure- 
 ment is about half an inch. Between its upper border and the 
 cricoid cartilage is a space about four or five lines in extent, where 
 the trachea is free ; this space, therefore, is the more preferable 
 situation for tracheotomy. But the vertical measurement of this 
 isthmus is sometimes of very considerable length. We have seen 
 it covering the trachea almost down to the sternum.f 
 
 The thyroid body is closely connected, by fibrous tissue, to the 
 sides of the trachea and cricoid cartilage. Hence it rises and falls 
 with the larynx in deglutition. 
 
 Taken as a whole, the thyroid varies in size in different indi- 
 viduals and at different periods of life. It is relatively larger in 
 the child than the adult, in the female than the male. In old 
 
 * Concerning the development of the lateral halves and central portion of the 
 thyroid body, see a paper by Callender in the Proceedings of the Eoyal Society, 
 
 1867. 
 
 f From the upper part of the isthmus, or from the adjacent border of either lobe, 
 most commonly the left, a conical prolongation of the thyroid body, called ' the 
 pyramid,' frequently ascends in front of the crico-thyroid membrane, as high as the 
 ' pomum Adami,' and is connected to the body of the os-hyoides by fibrous tissue. 
 In some subjects we may observe a few muscular fibres passing from the os-hyoides 
 to the pyramid. This constitutes the ' levator glandulse thyroideae ' (see preparation in 
 Museum of St. Earth. Hosp., Patholog. Series, No. 14) of some anatomists. There 
 are instances in which the pyramid is double ; and, lastly, I have seen a considerable 
 portion of this thyroid substance lying over the crico-thyroid membrane, completely 
 isolated from the rest of the organ. These varieties deserve notice, because any one 
 portion of this structure may become enlarged independent of the rost, and occasion a 
 bronchocele. 
 
THYROID BODY. 31 
 
 age it diminishes in size, becomes firmer, and occasionally contains 
 earthy matter. 
 
 But by far the most notable considerations in respect to the 
 thyroid body are the number, the large size, and the free inoscula- 
 tions of its blood-vessels. In fact, it appears to be composed of a 
 tissue of arteries and veins. The superior thyroid arteries come 
 from the external carotid and enter the front surface of the apex 
 of each lobe ; the inferior thyroid come from the subclavian, and 
 enter the under surface of the base. An artery, called the middle 
 thyroid, is observed in some subjects ; it comes from the arteria 
 innominata, or the arch of the aorta, and ascends directly in front 
 of the trachea to the isthmus. 
 
 Its veins are equally large, and form a plexus upon it. The 
 superior and middle thyroid veins cross the common carotid, and 
 open into the internal jugular. The inferior thyroid veins, two in 
 number, descend over the front of the trachea, communicate freely 
 with each other, and terminate in the left brachio-cephalic vein. 
 When you perform tracheotomy, bear in mind the size of these infe- 
 rior thyroid veins, and the possible existence of a middle thyroid 
 artery. 
 
 Its nerves are furnished by the laryngeal branch of the pneumo- 
 gastric and the middle and inferior cervical ganglia of the sympa- 
 thetic. They accompany the arteries. 
 
 The thyroid body weighs from one to two ounces, and belongs 
 to the class of ductless glands, since no excretory duct 
 
 Structure of . . , . . 
 
 the thyroid has been discovered. It is invested b}^ a thin covering 
 gland. Q f conc i ense( } cellular tissue which penetrates into it, 
 
 imperfectly dividing it into lobes and supporting the vessels as 
 they enter it. It consists of a multitude of cells, which vary in 
 size, and do not communicate with each other. Some of them 
 may be recognised with the naked eye ; but the greater number 
 require the aid of the microscope. In hypertrophy of the gland 
 we sometimes see them as large as a horsebean, or even larger. 
 These cells are lined by a limitary membrane and contain a 
 glairy transparent fluid, in which are found a large number of 
 nuclei and nucleated cells. The arteries ramify most minutely 
 
32 THYROID BODY. 
 
 upon their walls. Of its functions nothing is with certainty 
 known. The presumption is, that it is concerned in the elabora- 
 tion of the blood. 
 
 An enlargement of the thyroid body is termed a * Bronchocele.' 
 If the relation of its lobes to the trachea and oesophagus be pro- 
 perly understood, it is easy to predicate the consequences which 
 may result from their enlargement. The nature and severity of 
 the symptoms will to a certain extent be determined by the part 
 of the organ affected. If the isthmus be enlarged, difficulty in 
 breathing will probably be the prominent symptom ; and an en- 
 largement of the left lobe is more likely to produce a difficulty in 
 swallowing, on account of the inclination of the oesophagus towards 
 the left side. 
 
 An instance is related by Allen Burns in which the isthmus was 
 placed between the trachea and the oesophagus. It must be 
 obvious that enlargement of a part so situated would occasion great 
 difficulty in swallowing. I have seen two cases in which the lateral 
 lobes projected so far inwards that they completely embraced the 
 back of the oesophagus. 
 
 Small absorbent glands are observed about the thyroid body, 
 especially in front of the trachea ; one is often situated over the 
 crico-thyroid membrane. These glands, if enlarged by disease, 
 might be mistaken for a small bronchocele. 
 
 In the areolar tissue which surrounds the great 
 cervical vessels of the neck, we meet with a series of absorbent 
 absorbent glands, called the deep cervical. They form an unin- 
 terrupted chain (whence their name glandulce con- 
 catenatce\ from the base of the skull, along the side of the neck, 
 to the clavicle, beneath which they are continuous with the 
 thoracic and the axillary glands. Some of these glands lie anterior 
 to the common carotid artery, others, between it and the spine. 
 This disposition explains the well-known fact, that, when these 
 glands are enlarged, the great vessels and nerves of the neck are 
 liable to become imbedded in their substance. 
 
 The glands are particularly numerous near the division of the 
 common carotid, by the side of the pharynx, and the posterior 
 
CENTRAL LINE OF THE NECK. 33 
 
 belly of the digastricus. The absorbents connected with them 
 come from all parts of the head and neck. These vessels unite, 
 to form, on both sides of the neck, one or more absorbent trunks, 
 called the jugular. On the left side this jugular trunk joins the 
 thoracic duct, or opens by a separate orifice into the left subclavian 
 vein : on the right it always opens into the subclavian vein. 
 
 The contiguity of the glands to the great vessels and nerves of 
 the neck explains the symptoms produced by their enlargement. 
 The tumour may be so situated as to be raised and depressed by 
 the pulsation of the carotid, and thus simulate an aneurism. A 
 careful examination, however, will distinguish between a real and 
 an apparent pulsation. By grasping the tumour we become sen- 
 sible that the rising and falling do not depend upon any varia- 
 tion of its magnitude, but upon the impulse derived from the 
 artery ; consequently, if the tumour be lifted from the vessel, all 
 feeling of pulsation ceases. 
 
 Study well the parts in the central line of the neck 
 (% ?> P- 25 )- Beginning at the chin, we observe the 
 
 tral line insertions of the digastric muscles. Below these is 
 neck. 6 tne junction, or 'raphe,' of the mylo-hyoid muscles. 
 
 Then comes the os-hyoides. Below the os-hyoides 
 comes the thyro-hyoid membrane, attached above to the upper 
 border of the hyoid bone and below to the thyroid cartilage. 
 Below this is the pomum Adami, or notch of the thyroid carti- 
 lage. Below the thyroid cartilage is the cricoid. These two 
 cartilages are connected by the crico-thyroid membrane. Below 
 the cricoid c. is the trachea. This is crossed by the isthmus of 
 the thyroid body, and lower down it is covered by the inferior 
 thyroid veins. 
 
 Now the chief surgical interest lies just above and below the 
 cricoid cartilage. We can feel this cartilage very plainly in the 
 living subject at any age, no matter how fat. In laryngotomy, 
 the crico-thyroid membrane is divided transversely. The mem- 
 brane should be divided close to the edge of the cricoid c., for two 
 reasons: 1. In order to be farther from the vocal cords. 2. To 
 avoid the crico-thyroid artery which crosses the middle of the 
 
 D 
 
34 CENTRAL LINE OF THE NECK. 
 
 membrane. If more room be required, tbe cricoid cartilage should 
 be divided longitudinally. 
 
 In tracheotomy, the trachea, is opened by a perpendicular inci- 
 sion, either above the isthmus of the thyroid body, or below it. 
 The operation above the isthmus, if there be space enough for the 
 introduction of the canula, is the easier and safer of the two ; for 
 here the trachea is nearer to the surface, and no large blood- 
 vessels are, generally speaking, in the way. The space available 
 measures from a quarter to half an inch ; and the isthmus is not 
 so firmly adherent to the trachea as to prevent its being drawn 
 downwards for a short distance. However, it is right to state, 
 that in one case out of every eight or ten, there is no available 
 space. 
 
 Tracheotomy below the isthmus is neither an easy nor a safe 
 operation, for many reasons: 1. The trachea recedes from the 
 surface as it descends, so that just above the sternum it is nearly 
 an inch and a half from the skin. 2. The large inferior thyroid 
 veins are in the way. 3. A middle thyroid artery may run up in 
 front of the trachea, direct from the arteria innominata. 4. The 
 arteria innominata itself lies sometimes upon the trachea higher 
 than usual, and may, therefore, be in danger. 5. The left brachio- 
 cephalic vein in some cases crosses the trachea above the edge of 
 the sternum instead of below it. The celebrated French surgeon 
 Beclard used to relate in his lectures the following occurrence : 
 A student had fallen into the Seine, and was nearly drowned. As 
 he was recovering very gradually, some kind friends attempted to 
 accelerate the process by making an opening into the trachea. In 
 so doing they wounded the brachio-cephalic vein. Blood poured 
 into the trachea, and the result was instantly fatal. 
 
 Some surgeons advocate the practice of dividing the isthmus 
 vertically, in order to get at the trachea beneath it. Let such 
 surgeons remember that an artery, which would bleed freely if 
 divided, generally runs along the upper edge of the isthmus. The 
 artery is a branch of the superior thyroid, and inosculates with a 
 corresponding branch on the opposite side. 
 
 Whoever pays attention to this subject in the dissecting-room 
 
SUBM AXILLARY REGION. 35 
 
 will soon be convinced of the fact, that not only large veins but 
 large arteries occasionally cross the crico-thyroid membrane as well 
 as the trachea. Every winter session convinces me more and 
 more of the necessity of cutting cautiously down to, and fairly ex- 
 posing the air tube, before we venture to open it. 
 
 When the platysma and the cervical fascia have been 
 
 removed from their attachment to the jaw, the most 
 submaxil- conspicuous object is the submaxillary gland. Observe 
 jrion^r that ^ ie f asc i a f rrns f r it a complete case. Beneath 
 the digas- the jaw we find several absorbent glands, of which some 
 angled" ^ e superficial to the salivary gland, others beneath it. 
 
 These glands receive the absorbents of the face, the 
 tonsils, and the tongue. 
 
 A little dissection will expose a muscle called the c digastricus,' 
 consisting of two distinct portions connected by a tendon. They 
 form, with the body of the jaw, a triangle, called the ' digastric,' 
 of which we propose to examine the contents. And first of the 
 digastric muscle itself. 
 
 The digastricus consists of two muscular bellies 
 
 united by an intermediate tendon. It arises from the 
 digastric fossa of the temporal bone, and is inserted close to the 
 symphysis of the lower jaw. Eaise the submaxillary gland to 
 see the intermediate tendon of the digastricus, the angle which it 
 forms, and how it is fastened by aponeurosis to the body and 
 greater cornu of the os-hyoides. Observe also that this aponeurosis 
 is connected in the mesial line with its fellow of the opposite side, 
 so that a fibrous expansion occupies the interval between the 
 anterior portions of the digastrici. 
 
 The chief action of the digastricus is to depress the lower jaw. 
 But if the lower jaw be fixed, then the muscle raises the os-hyoides, 
 as in deglutition. 
 
 The posterior belly of the digastricus is supplied by a nerve 
 from the facial ; the anterior belly by a branch from the mylo- 
 hyoidean nerve (which comes from the third division of the fifth 
 pair). 
 
 D 2 
 
36 
 
 SUBMAXILLARY REGION. 
 
 Stylo- 
 
 The stylo-hyoideus arises from the styloid process of 
 hyoideus. the temporal bone, and is inserted into the body of the 
 os-hyoides. This muscle runs close along the posterior 
 belly of the digastricus. Most frequently the digastric tendon 
 runs through the substance of it. Its nerve comes from the facial 
 
 Fig. 8. 
 
 Facial a. 
 Mylo-hyoid n. 
 
 Snbmental a. 
 
 Occipital 
 
 Hypoglossal n. . 
 
 Descendens noni n 
 Lingual ; 
 
 Internal jugular v 
 Superior thyroid a 
 
 Common carotid a. . . 
 
 DIGASTRIC TRIANGLE AND CONTENTS. 
 
 close to its exit from the stylo-mastoid foramen. Tts action is to 
 raise and draw back the os-hyoides. 
 
 The digastric triangle is bounded above by the body of the 
 lower jaw, parotid gland, and mastoid process of the temporal bone ; 
 behind by the posterior belly of the digastricus ; and in front by 
 
SUBMAXILLARY REGION. 37 
 
 the anterior belly. The objects we have to examine in this 
 triangle are twelve in number, as follow : 
 
 1. Submaxillary gland. 7. Stylo-maxillary ligament. 
 
 2. Facial vein. 8. Part of the parotid gland. 
 
 3. Facial artery. 9. Part of the external carotid artery. 
 
 4. Submental artery. 10. Mylo-hyoideus muscle. 
 
 5. Mylo-hyoidean nerve. 11. Hypoglossal nerve. 
 
 6. Submaxillary absorbent glands. 12. Part of the hyo-glossus muscle. 
 
 Submaxillar ^ n *^ e ordinary position of the head, the sub- 
 salivary maxillary gland is partially concealed by the jaw, 
 gland. j^ w h en kh e head f a n s back the gland is more ex- 
 
 posed. It is about the size of a chestnut, and is divided into 
 several lobes. Its upper margin is covered by the body of the 
 jaw; its lower margin overlaps the side of the os-hyoides. Its 
 cutaneous surface is flat, but the lobes on its deep surface are 
 irregular, and often continuous with those of the sublingual gland. 
 By raising the gland we find that it lies upon the mylo-hyoideus, 
 the hyo-glossus, the stylo-glossus, the tendon of the digastricus, 
 and a portion of the hypoglossal nerve, seen above the tendon. 
 The facial artery lies in a groove on its upper border ; and it is 
 separated from the parotid gland, which is situated behind it, by 
 the stylo-maxillary ligament. Mark these relations well, because 
 they are of importance, as we shall presently explain, in tying the 
 lingual artery. 
 
 The duct of the gland (Wharton's duct *) passes from its under 
 surface, runs forwards under the mylo-hyoideus and upon the 
 hyo-glossus muscle; it then passes beneath the gustatory nerve, 
 and subsequently runs between the sublingual gland and the 
 genio-hyo-glossus, to open into the floor of the mouth, by the side 
 of the frsenum linguae. Its length is about two inches ; its dimen- 
 sions are not equal throughout, for it is dilated about the middle, 
 and contracted at the orifice. Saliva, collected in the dilated 
 portion, is sometimes spirted to a considerable distance out of the 
 
 * Thorn. Wharton, Adenographia, seu glandularum totius corporis descriptio. 12mo. 
 Am'stel., 1659. 
 
38 SUBMAXILLARY REGION. 
 
 narrow orifice, in consequence of the sudden contraction of the 
 neighbouring muscles. 
 
 An abnormal dilatation of the submaxillary duct is called a 
 ' ranula.' It makes a tumour with semi-transparent walls, percep- 
 tible beneath the tongue. In some cases, however, what appears 
 to be a 6 ranula ' is in reality a cyst formed in the loose areolar 
 tissue under the tongue, or an enlargement of one of the small 
 bursae which are normally placed here."* 
 
 The facial vein does not accompany the facial artery. 
 Facial j^. i eaveg ^6 f ace a 0e an terior edge of the masseter 
 
 m., then runs over the submaxillary gland, the digas- 
 tricus and stylo-hyoideus and the carotid artery, to join the internal 
 jugular. This is the rule but there are frequent exceptions. 
 The principal point to remember is, that the vein runs superficial 
 to the gland, and that we must be cautious in opening abscesses 
 under the jaw. 
 
 The facial artery is the third branch of the external 
 artery carotid. It runs tortuously under the hypoglossal nerve, 
 
 the posterior belly of the digastricus and stylo-hyoideus, 
 and underneath or through the substance of the submaxillary 
 gland to the face, where it appears at the anterior border of the 
 masseter. Below the jaw the facial gives off the four following 
 branches : 
 
 1. The ascending or inferior palatine artery runs up between 
 the stylo-glossus and the stylo-pharyngeus in. to the soft palate 
 and tonsils, and inosculates with the descending palatine, a branch 
 of the internal maxillary. 
 
 2. The tonsillar runs up between the internal pterygoid and 
 the stylo-glossus m., then, perforating the superior constrictor, sup- 
 plies the tonsil and root of the tongue. 
 
 3. Glandular branches to the submaxillary gland. 
 
 4. The submental runs forwards upon the mylo-hyoideus muscle, 
 under the inferior maxilla, turns over the chin, and inosculates 
 with the terminal branches of the inferior dental and inferior 
 
 * These sublingual bursse were first described by Fleischmcinn, De novis sub- 
 lingua bursis, Nuremberg, 1841. 
 
SUBMAXILLARY REGION. 39 
 
 labial. It supplies the mylo-hyoideus, the anterior belly of the 
 digastricus, and the sublirigual absorbent glands. 
 M lo Look for the mylo-hyoidean nerve near the sub- 
 
 hyoidean mental artery. The nerve comes from the inferior 
 nerve. dental (before its entrance into the dental foramen), 
 
 and running along a groove on the inner side of the jaw, advances 
 between the bone and the internal pterygoid m., to supply the 
 mylo-hyoideus and the anterior belly of the digastricus. 
 
 The submaxillary absorbent glands receive the absorbent vessels 
 of the face and the tongue. We often see them enlarged in cancer 
 of the tongue and cancer of the lower lip. It is worth remem- 
 bering that there are absorbent glands in the mesial line below 
 the chin. 
 
 The mylo-hyoideus arises from the mylo-hyoid ridge 
 s ^ tne ^ ower J aw ? as ^ ar back as the last molar tooth, 
 and is inserted into the body of the os-hyoides. Its 
 fibres pass obliquely downwards and forwards, the posterior only 
 are inserted into the body of the os-hyoides, the anterior being 
 attached to a median tendinous line, termed a 'raphe.' Thus the 
 muscles of opposite sides form a muscular floor for the mouth. It 
 is supplied with nerves by the mylo-hyoid branch of the dental, 
 with blood by the submental a. The muscles of opposite sides 
 conjointly elevate the os-hyoides and the floor of the mouth as 
 in deglutition. 
 
 gt , lo _ This is simply a deep layer of the cervical fascia, 
 
 maxillary extending from the angle of the jaw to the styloid pro- 
 Lgamont. cegg ^ j^. j g a | [)roa ^ soee t o f fascia, and separates the 
 
 submaxillary gland from the parotid. It is continuous with the 
 fascia covering the pharynx ; this gives it a surgical interest, 
 because it prevents accumulations of matter formed near the 
 tonsils and upper part of the pharynx, from coming to the sur- 
 face. 
 
 The remaining objects seen in the submaxillary triangle, 
 namely, the parotid gland, the external carotid, the hypoglossal 
 nerve, and the hyo-glossus muscle, will be described presently when 
 they can be better seen. Your attention should now be directed 
 
40 SUBMAXILLARY REGION. 
 
 to a piece of surgical anatomy, which will enable you readily to 
 find and tie the lingual artery. It is this : 
 
 A horizontal incision being made along the body and greater 
 cornu of the os-hyoides through the skin, the platysma, and 
 the cervical fascia, you will come at once upon the lower edge 
 of the submaxillary gland. Lift up the gland, which can be easily 
 done, and underneath it you will observe that the tendon of the 
 digastricus makes two sides of a triangle, of which the base is 
 formed by the hypoglossal nerve crossing the hyo-glossus m. 
 Within this little triangle, cut transversely through the fibres of 
 the hyoglossus, and under them is the lingual artery. The first 
 time you perform this operation on the dead subject, you will 
 probably miss the artery and cut (through the middle constrictor) 
 into the pharynx. 
 
 The facial vessels must now be divided immediately below the 
 jaw. Reflect the anterior belly of the digastricus from its in- 
 sertion ; detach the mylo-hyoideus from the middle line and the 
 os-hyoides, and turn it over the body of the jaw, taking care not 
 to injure the muscle and structures beneath. The lower jaw must 
 now be sawn through, a little to the dissector's side of the sym- 
 physis, and the bone drawn upwards by hooks. The tongue should 
 be drawn out of the mouth, and fastened by hooks. The os- 
 hyoides should be drawn down by means of hooks, so as to put the 
 parts on the stretch. All this done, we have to make out the 
 following objects, represented in fig. 9, p. 41. 
 
 1. Genio-hyoideus. 6. Sublingual gland. 
 
 2. Hyo-glossus. 7. Hypoglossal nerve. 
 
 3. Stylo-glossus. 8. Gustatory nerve. 
 
 4. Genio- hyo-glossus. 9. Submaxillary ganglion. 
 
 5. Submaxillary duct. 10. Lingual artery. 
 
 The genio-hyoideus arises from the inferior tubercle 
 ho/deus behind the symphysis of the jaw, and is inserted into 
 the front of the bod}' of the os-hyoides. This round 
 muscle is situated in the mesial line, parallel to its fellow. Its 
 nerve comes from the hypoglossal, and its blood from the 
 lingual artery. Its action is to draw the os-hyoides forwards and 
 
SUBMAXILLARY REGION. 
 
 41 
 
 Hyo-glossus. 
 
 upwards ; and if the hyoid bone be fixed, it depresses the lower 
 jaw. 
 
 The hyo-glossus arises from the body, the greater 
 and lesser cornua of the os-hyoides, and is inserted into 
 the posterior two-thirds of the side of the tongue. It is a square 
 and flat muscle, and its fibres ascend nearly perpendicularly from 
 origin to insertion. Its nerve comes from the hypoglossal, and its 
 blood from the lingual artery 3 Its action (with that of its fellow) 
 
 Styloid process . . 
 
 Glosso-pharyngeal n. - 
 
 hypoglossal n. 
 occipital a. . 
 
 Submaxillary gan- 
 glion 
 
 Duct of submaxillary 
 gland 
 
 Middle constrictor m. 
 
 Fig. 9. 
 
 - Chorda tympani n. 
 Gustatory n. 
 
 Lingual a 
 
 Descendens noni n. . 
 
 MUSCLES, VESSELS, AND NERVES OF THE TONGUE. 
 
 is to depress the tongue. Observe the several objects which lie 
 upon the hyo-glossus ; namely, the hypoglossal and gustatory 
 nerves, the submaxillary ganglion, the duct of the submaxillary 
 gland, and the sublingual gland. Beneath the hyo-glossus muscle 
 lie the lingual artery, part of the middle constrictor of the pharynx, 
 part of the genio-hyo-glossus, the lingualis muscle, and the glosso- 
 pharyngeal nerve. 
 
42 SUBMAXILLARY REGION. 
 
 The genio-hyo-glossus arises by a tencjon from the 
 Geniohyo upper tubercle behind the symphysis of the lower jaw, 
 glossus. and is inserted into the os-hyoides and the tongue from 
 the base to the apex. It is the largest and most important 
 of the muscles of the tongue. It is fan-shaped, with the apex 
 attached to the symphysis : thence its fibres radiate into the entire 
 length of the tongue. It derives its nerves from the hypoglossal, 
 and its blood from the lingual artery. Its action is various. The 
 posterior fibres, by raising the os-hyoides and drawing forwards 
 the base of the tongue, protrude the tongue out of the mouth ; 
 the anterior draw the tongue back again. When every part of the 
 muscle acts, it draws down the whole tongue, and is therefore one 
 of the chief muscles concerned in suction. 
 
 The stylo-glossus, a long and slender muscle, arises 
 glossus from the apex of the styloid process and the stylo- 
 maxillary ligament, and is inserted along the side of 
 the tongue. It runs outside the hyo-glossus nearly to the tip of 
 the tongue. Its nerve comes from the hypoglossal. Its action is 
 to retract the tongue. 
 
 H Q The hypoglossal, or ninth cerebral nerve, is the motor 
 
 glossal nerve of the muscles of the tongue. It arises (by 
 
 several roots) from the front of the medulla oblongata 
 between the pyramid and the olive. After leaving the skull 
 through the anterior condyloid foramen, it lies beneath the internal 
 jugular vein and internal carotid artery, where it is intimately 
 connected with the pneumogastric nerve ; it then comes up 
 between the artery and vein, and, immediately below the posterior 
 belly of the digastricus, curves forwards round the occipital, over 
 both carotid and facial arteries. It then crosses the hyo-glossus 
 muscle, and passing beneath the mylo-hyoid, divides into branches 
 which supply all the muscles of the tongue ; namely, the stylo- 
 glossus, hyo-glossus, genio-hyo-glossus, lingualis, and the genio- 
 hyoideus. As it curves round the occipital artery, the hypoglossal 
 nerve sends the ' descendens noni ' to the depressors of the 
 os-hyoides (p. 25). It also sends a nerve to the thyro-hyoideus, 
 which proceeds from it where it crosses over the external carotid. 
 
SUBMAXILLARY REGION. 43 
 
 Near the anterior border of the hyo-glossus, it communicates with 
 the gustatory nerve. (Fig. 9.) 
 
 The hypoglossal at its origin is purely a motor nerve. But after 
 leaving the skull, it receives communications from the first two 
 cervical nerves. These communications are important physiologi- 
 cally for two reasons : 1. They account for the hypoglossal nerve 
 containing sensitive fibres. 2. They contribute the greater part of 
 the filaments of the ' descendens noni.' It is also connected with 
 the pneumogastric and sympathetic nerves at the base of the skull. 
 Sublin ual ^ e sublingual gland lies immediately beneath the 
 salivary mucous membrane of the floor of the mouth. Its shape 
 gland. j g oblong^ wifa the long axis (about an inch and a half) 
 
 directed from before backwards. It rests upon the upper surface of 
 the mylo-hyoid muscle, and towards the mesial line it* is in contact 
 with the hyo-glossus and the genio-hyo-glossus. 
 
 The ducts of the sublingual gland (ducts of Rivinus*) vary in 
 number from eight to twenty. They terminate by minute open- 
 ings behind the orifice of the submaxillary duct, along a ridge 
 upon the floor of the mouth. The ducts of some of the lobes ter- 
 minate in the submaxillary duct. 
 
 The duct of the submaxillary gland may now be traced across 
 the hyo-glossus, and under the gustatory nerve to the floor of the 
 mouth. 
 
 This nerve is a branch of the inferior maxillary or 
 nerve. ' OTy third division of the fifth pair of cerebral nerves. It 
 descends between the ramus of the jaw and the internal 
 pterygoid muscle, comes forwards over the superior constrictor of 
 the pharynx and along the upper part of the hyo-glossus, crossing 
 at an acute angle over the duct of the submaxillary gland. Having 
 reached the under part of the tongue, the nerve divides into fila- 
 ments which supply the papillae on its anterior three-fourths. 
 Submaxil Look a t the lower border of the gustatory nerve 
 
 lary gan- before it crosses the submaxillary duct : you will find a 
 ghon. small ganglion, about the size of a pin's head. Like 
 
 the other ganglia in connection with the branches of the fifth pair, 
 
 * Aug. Quirin. Rivinus, de Dyspepsia. Lips. 1678. 
 
44 SUBMAXILLARY REGION. 
 
 it receives nerve-filaments of three different kinds viz. motor, 
 sensitive, and sympathetic. Its motor root is the chorda tyrnpani, 
 which, apparently a branch of the gustatory, is derived from the 
 facial nerve (a nerve of motion). Its sensitive roots proceed from 
 the gustatory ; and its connection with the sympathetic system of 
 nerves is established by a branch which comes from the f nervi 
 molles ' round the facial artery. Thus provided with nerves, the 
 ganglion supplies the submaxillary and sublingual glands and 
 their ducts. 
 
 The lingual artery is generally the second branch of 
 the external carotid. Curving slightly upwards from its 
 origin, the artery soon runs forwards beneath the hyo- 
 glossus muscle, parallel to the os-hyoides. At the anterior edge of 
 the hyo-glossus it ascends to the under surface of the tongue, and 
 is continued forwards to the apex of the tongue under the name of 
 ( ranine.' The curves made by the artery are for the purpose of 
 allowing the elongation of the tongue. Under the hyo-glossus, the 
 artery lies upon the middle constrictor of the pharynx, and the 
 genio-hyo-glossus muscles ; in the substance of the tongue, it lies 
 between the genio-hyo-glossus and the lingualis. Its branches are 
 as follow : 
 
 1 . The hyoid, a small artery which runs along the upper border 
 of the hyoid bone, supplying the muscles and anastomosing with 
 its fellow. 
 
 2. The dorsales linguce, two or more, which run under the 
 hyo glossus to the back of the tongue. 
 
 3. The sublingual, arising near the anterior border of the hyo- 
 glossus, supplies the sublingual gland, the mylo-hyoideus, and the 
 mucous membrane of the mouth and gums. This artery gene- 
 rally gives off the little artery of the f fraenum linguae/ which is 
 sometimes wounded in cutting the fraenum in children who are 
 tongue-tied ; especially when we neglect the rule of pointing the 
 scissors downwards and backwards. 
 
 4. The ranine is the termination of the lingual artery. As it 
 runs forwards to the tip of the tongue along the outer side of the 
 genio-hyo-glossus, it distributes branc^gs to the tongue, and at the 
 tip inosculates slightly with its fellow. V 
 
EXTERNAL CAROTID ARTERY. 45 
 
 The lingual vein runs over the hyo-glossus, and terminates in 
 the internal jugular. 
 
 The best place for finding and tying the lingual artery has 
 already been mentioned. The rule laid down is trustworthy only 
 when the artery runs its normal course. I have known an instance 
 in which a good anatomist failed in an attempt to tie the lingual 
 artery, because the vessel arose from the facial behind the sub- 
 maxillary gland, and then passed through the mylo-hyoideus to 
 reach the tongue. 
 
 Study next the course and relations of the external carotid 
 artery, and its branches in the neck. In preparing a view of them, 
 observe that nearly all the veins lie in front of their corresponding 
 arteries. 
 
 The external carotid arises from the common carotid 
 
 bourse ana 
 
 relations about the level of the upper border of the thyroid car- 
 tenial ca~ tilage. I* ascends beneath the hypogiossal nerve, the 
 rotid ar- facial and lingual veins, the posterior belly of the 
 digastricus and stylo-hyoideus, enters the parotid gland, 
 where it lies beneath the facial nerve and external jugular vein, 
 and terminates near the neck of the jaw, by dividing into the 
 temporal and internal maxillary arteries. 
 
 Notice the relative position which the external and internal 
 carotids bear to each other. The external lies at first on the same 
 plane with, but nearer to the side of the pharynx than the internal. 
 The external, however, soon changes its position, and crosses 
 obliquely in front of the internal to reach the space between the 
 angle of the jaw and the mastoid process. The internal carotid 
 ascends perpendicularly by the side of the pharynx to the base of 
 the skull. 
 
 The external is separated from the internal carotid by the stylo- 
 glossus and stylo-pharyngeus muscles, the glosso-pharyngeal nerve, 
 and the stylo-hyoid ligament. 
 
 The external carotid gives off the following branches : 
 
 1. The superior thyroid. 5. The posterior auricular. 
 
 2. The lingual. 6. The internal maxillary. 
 
 3. The facial. 7- The temporal. 
 
 4. The occipital. 8. The ascending pharyngeal. 
 
46 BRANCHES OF THE EXTERNAL CAROTID. 
 
 The superior thyroid, the first branch of the external 
 Superior carotid, arises just below the great cornu of the os- 
 aitery. d hyoides. It runs beneath the omo-hyoid, sterno-hyoid, 
 and sterno-thyroid muscles to the upper and front 
 surface of the thyroid body, in which it terminates. Its branches 
 are the four following : 
 
 1. The fiyoid, a small muscular branch, runs horizontally in- 
 wards below the greater cornu of the os-hyoides, and anastomoses 
 with its fellow. 
 
 2. The superior laryngeal branch, accompanied by the supe- 
 rior laryngeal nerve, runs beneath the thyro-hyoid muscle, 
 perforates the thyro-hyoid membrane (sometimes the thyroid 
 cartilage), and supplies the muscles and the mucous membrane 
 of the larynx. 
 
 3. The sterno-mastoid, a small branch variable as to origin, 
 descends over the sheath of the carotid artery to the mastoid 
 muscle. 
 
 4. The crico-thyroid, an artery of great interest in reference to 
 the operation of laryngotomy, crosses the crico-thyroid membrane, 
 and communicates with a corresponding branch on the opposite 
 side (fig. 7, p. 25). One or two small branches pass through the 
 membrane to the interior of the larynx. It is important to know 
 that the crico-thyroid artery often varies in direction and size. In 
 most cases it is small, and runs across the centre of the membrane; 
 we should therefore be least likely to wound it in laryngotomy, by 
 dividing the membrane close to the cricoid cartilage. But it is 
 by no means infrequent to find this artery of considerable size, 
 taking an oblique or a perpendicular direction in front of the 
 membrane, and finally distributed to one of the lobes of the 
 thyroid body. I have seen several instances in which the mem- 
 brane was crossed by the main trunk of the superior thyroid. 
 These facts should establish the practical rule in laryngotomy, not 
 to make an opening into the larynx until we have fairly exposed 
 the parts, and ascertained whether any large artery lies in the 
 way. 
 
 Among the many arterial inosculations about the thyroid bodv 
 
BRANCHES OF THE EXTERNAL CAROTID. 47 
 
 are two which deserve notice ; the one is formed between the two 
 superior thyroid arteries along the upper border of the isthmus, 
 the other takes place along the back part of the lateral lobe 
 between the superior and inferior thyroid. 
 
 The superior thyroid vein crosses the sheath of the common 
 carotid, and joins the internal jugular. 
 
 The superior laryngeal nerve, mentioned as accompanying the 
 superior laryngeal artery, comes from the inferior ganglion of the 
 pneumogastric. It descends by the side of the pharynx, behind 
 both carotid arteries, enters the larynx through the thyro-hyoid 
 membrane, and supplies the mucous membrane of the larynx with 
 its exquisite sensibility. Some of its branches may be traced 
 upwards to supply the epiglottis and base of the tongue ; others 
 descend to the ( rima glottidis;' and a large branch passes down 
 behind the ala of the thyroid cartilage to join the recurrent 
 laryngeal nerve. 
 
 Before it enters the larynx, the nerve sends the ( external 
 laryngeal ' branch to supply the crico-thyroid muscle. 
 Lingual The lingual artery and its branches have been de- 
 
 artery, scribed (p. 44). 
 
 Facial The facial artery and its branches below the jaw have 
 
 artery. been described (p. 38). 
 
 The occipital artery, the fourth branch of the ex- 
 artery ternal carotid, runs backwards along the lower border 
 
 of the digastricus towards the mastoid process. It then 
 passes under all the muscles inserted into the mastoid process 
 namely, the sterrio-mastoid, the splenius capitis, and the trachelo- 
 mastoid. Arrived at the back of the head, the artery runs super- 
 ficial to the complexus, and divides into wide-spreading branches 
 for the supply of the scalp. Observe that in the first part of its 
 course, the occipital artery crosses over the internal carotid artery, 
 the internal jugular vein, the spinal accessory nerve, and is itself 
 crossed by the hypoglossal nerve. It sends off the three following 
 branches : 
 
 1. Thesterno-mastoid, which enters the muscle with the nervus 
 accessorius. 
 
48 BRANCHES OF THE EXTERNAL CAROTID, 
 
 2. The posterior meningeal ascends with the internal jugular 
 vein, and enters the cranium through the foramen jugulare to 
 supply the dura mater. 
 
 3. The princeps cervicis, which we shall see better hereafter, 
 runs down the back of the neck under the complexus, supplies 
 this muscle and the serni-spinalis colli. 
 
 The occipital vein usually terminates in the internal jugular, 
 sometimes in the external. 
 
 The posterior auricular artery, the fifth branch of 
 Posterior , -, , 
 
 auricular the external carotid, arises above the digastric muscle, 
 
 artery ' and runs, under cover of the parotid gland, to the 
 
 furrow between the cartilage of the ear and the mastoid process. 
 Above the mastoid process it divides into two branches, a posterior 
 which inosculates with the occipital, and an anterior which com- 
 municates with the temporal. It supplies the back of the scalp 
 and the cartilage of the ear. Its only named branch is the stylo- 
 mastoid, a very constant little artery, which runs through the 
 stylo-mastoid foramen to the tympanum of the ear. 
 Posterior ^ e P os t er i r auricular nerve lies close to the corre- 
 
 auricular spending artery. It is the first branch of the facial 
 
 after its exit from the stylo-mastoid foramen. It runs 
 behind the ear and divides into an auricular branch which supplies 
 the retrahens and attollens aurem, and an occipital branch distri- 
 buted to the posterior belly of the occipito-frontalis. 
 Ascending ^ D ^ s ar t ei 7 arises near the division of the common 
 pharyngeal carotid. It ascends between the internal carotid and 
 
 the side of the pharynx to the base of the skull, lying 
 upon the rectus capitis anticus major. It gives off some pharyn- 
 geal branches which supply the constrictor muscles. It then 
 enters the pharynx above the free border of the superior con- 
 strictor, and terminates on the soft palate, the Eustachian tube, 
 and the tonsils. It gives off a meningeal branch, which passes 
 through the foramen lacerum medium to the dura mater in the 
 middle fossa. 
 
 The examination of the two remaining branches of the external 
 carotid namely, the internal maxillary and temporal, must be 
 
CERVICAL PLEXUS. 49 
 
 for the present postponed. Meantime, let us make out the deepi 
 cervical plexus and its branches. 
 
 Cervical ^ n * s P^ exus ^ s formed by the anterior branches of 
 
 plexus of the four upper cervical nerves. It consists of a series 
 of loop-like communications, which take place between 
 these nerves, close to the transverse processes of the four upper 
 cervical vertebrae. The plexus is situated behind the sterno- 
 mastoid and internal jugular vein, and lies in front of the scalenus 
 medius and the levator anguli scapulae. 
 
 The plexus gives off superficial and deep branches. The super- 
 ficial branches have been already described (p. 16). 
 
 The deep branches may be divided into an internal and an 
 external series. 
 
 INTERNAL SERIES. 1. The phrenic arises from the third, fourth, 
 and fifth cervical nerves, and passes through the thorax to be 
 distributed to the diaphragm. 
 
 2. The communicantes noni come from the second and third 
 cervical nerves, wind round the internal jugular vein, and join the 
 descend ens noni in front of the carotid sheath, supplying the de- 
 pressor muscles of the os-hyoides and larynx. 
 
 3. Muscular branches to the recti antici and lateralis and longus 
 colli muscles. 
 
 4. Branches which communicate with the pneumogastric, hypo- 
 glossal, and sympathetic nerves, and one to join the fifth cervical. 
 
 EXTERNAL SERIES. 1. One or more branches to the nervus 
 accessorius. 
 
 2. Muscular branches to supply the trapezius, levator anguli 
 scapulae, scalenus medius, and sterno-mastoid. 
 
 The clavicle should now be sawn through the middle, and the 
 sternal half raised with the sterno-mastoid attached, so that the 
 bone can be replaced, to study its relation to the subjacent parts. 
 The scalene muscles and the subclavian artery throughout its whole 
 course must next be carefully dissected. 
 
 The scalene muscles, so called from their resemblance to a 
 scalene triangle, extend from the transverse processes of the 
 cervical vertebrae to the first and second ribs. They may be con- 
 
 j; 
 
50 SCALENE MUSCLES. 
 
 sidered as intercostal muscles, since the transverse processes of the 
 cervical vertebrae are but rudimentary ribs. Anatomists describe 
 them as three separate muscles an anterior, a middle, and a 
 posterior; the anterior and middle are attached to the first rib, the 
 posterior to the second. In plan and purpose these three muscles 
 are one. 
 
 Scalenus Tne scalenus anticus arises from the anterior tubercles 
 
 aoticus. O f the transverse processes of the third, fourth, fifth, and 
 sixth cervical vertebrae, and is inserted by a flat tendon into the 
 tubercle on the inner border of the first rib. 
 
 Scalenus The scalenus medius arises from the posterior 
 
 medius. tubercles of the transverse processes of the six lower 
 cervical vertebrae, and is inserted into the first rib behind the 
 scalenus anticus. 
 
 Scalenus The scalenus posticus arises from the posterior 
 
 posticus. tubercles of the transverse processes of the two or three 
 lower cervical vertebrae, and is inserted into the second rib between 
 its tubercle and angle. 
 
 The scalene muscles are important agents in raising the thorax, 
 in a deep inspiration. Take a deep breath, and you can easily feel 
 them contracting. They can bend the cervical portion of the 
 spine, if their lower attachment be the fixed point, as in rising 
 from the recumbent position. 
 
 The scalenus anticus is just one of those muscles about which 
 we ought to know well all that lies in front of it, and all that lies 
 behind it. In front of it are, the phrenic nerve, the subclavian 
 vein, the supra-scapular and posterior scapular arteries. Behind 
 it are the subclavian artery and the five nerves which form the 
 brachial plexus. 
 
 Make your finger familiar with the feel of the tubercle on the 
 first rib, to which the scalenus anticus is attached. This tubercle 
 is the best guide to the subclavian artery, for it guides you to the 
 outer edge of the scalenus anticus, where you must look for the 
 vessel. Is the scalenus anticus entirely concealed from view by the 
 stern o-mastoid or not ? This will depend upon the breadth of the 
 clavicular attachment of the sterno-mastoid. As a general rule, it 
 
 "* 
 
SUBCLAVIAN ARTERY, 51 
 
 may be said, that the scalene muscle is concealed by the sterno- 
 mastoid, and that consequently, in tying the subclavian artery, it 
 will greatly facilitate the operation, if the clavicular origin of the 
 muscle be partially divided. 
 
 Phrenic The phrenic nerve runs down in front of the scalenus 
 
 nerve. ariticus, from the outer to the inner border. It arises 
 
 from the third, fourth, and fifth cervical nerves, but chiefly from 
 the fourth. It enters the chest between the subclavian artery and 
 vein, crosses in front of the internal mammary artery, and con- 
 tinues its course between the pericardium and pleura, in front of 
 the root of the lung, to the diaphragm, which it supplies. 
 
 When the spinal cord is injured above the fourth cervical ver- 
 tebra, the origin of the phrenic is implicated ; therefore the dia- 
 phragm, as well as the other muscles of inspiration, are paralysed. 
 Death is the immediate result.* 
 
 COURSE AND RELATIONS OF THE SUBCLAVIAN ARTERIES. 
 
 The left subclavian artery differs from the right, not only in its 
 origin, but in the relations of the first part of its course. The 
 right should, therefore, be examined first, and then the differences 
 between it and left. 
 
 The right subclavian artery is one of the two great branches 
 
 into which the arteria innominata divides behind the 
 
 clavian ar- sterno-clavicular joint. It runs outwards behind the 
 
 ter y* scalenus anticus, then inclines downwards over the 
 
 * The phrenic nerve is frequently joined by a filament from that branch of the 
 brachial plexus which supplies the subclavius muscle. It is important to be aware 
 that cases sometimes occur in which this seemingly insignificant filament is a branch 
 of considerable size, and forms the greater portion of the phrenic itself. I have met 
 with many instances in which this accessory branch was larger than the regular 
 trunk ; in all of them it crossed over the subclavian artery in the third part of its 
 course, and would probably have been injured in the operation of tying this vessel. 
 That such an accident has actually happened is recorded by Bransby Cooper in his 
 surgical lectures. He speaks of having injured this accessory branch of the phrenic 
 in tying the subclavian artery. The patient had incessant spasm of the diaphragm 
 till he died. 
 
 K '2 
 
5*2 SUBCLAVIAN ARTERY. 
 
 first rib, at the lower border of which it takes the name of ' axil- 
 lary.' The artery describes a curve, of which the greatest con- 
 vexity is between the scalene muscles. The height to which the 
 arch ascends varies. Generally, it rises higher in women than in 
 men, on the right side than on the left. 
 
 To study its relations more precisely, the course of the sub- 
 clavian is divided into three parts : 1. The part which intervenes 
 between its origin and the inner border of the scalenus anticus. 
 2. That which lies behind the scalenus. 3. That which intervenes 
 between the outer border of the scalenus and the lower border of 
 the first rib. 
 
 The first portion of the artery lies deeply in the neck and passes 
 upwards and outwards to the inner border of the scalenus anticus. 
 It is covered by the skin, platysma, superficial and deep fasciae, 
 the sternal end of the clavicle, the stern o-mastoid, sterno-hyoid, 
 and sterno-thyroid muscles, and a layer of deep fascia, continued 
 from the inner border of the scalenus anticus. It is crossed by 
 the internal jugular and vertebral veins, by the pneumogastric 
 and phrenic nerves, and by some cardiac filaments of the 
 sympathetic. Behind the artery are the recurrent branch of 
 the pneumogastric, the sympathetic nerve, the apex of the lung 
 and the pleura. Three branches arise from this portion of the 
 subclavian viz., the vertebral, internal mammary, and thyroid 
 axis. 
 
 In the second part of its course, the artery lies between the 
 scalene muscles. It is covered by skin, platysma, and superficial 
 fascia, by the clavicular origin of the sterno-mastoid, the deep 
 cervical fascia, and by the scalenns anticus and phrenic nerve 
 which separate it from the subclavian vein. Behind the artery 
 is the scalenus medius ; above it, is the brachial plexus; Only one 
 branch, the superior intercostal, is given off from this part of the 
 artery. 
 
 In the third part of its course, the artery passes downwards and 
 outwards, and lies upon the surface of the first rib. Here it is 
 covered by the skin, platysma, and two layers of the cervical 
 fascia ; subsequently by the supra-scapular artery, the clavicle, the 
 
SUBCLAVIAN ARTERY. 
 
 53 
 
 subclavius muscle, with its nerve ; and, what is of much more con- 
 sequence, it is here crossed by the external jugular and (often) the 
 supra and posterior scapular veins ; so that we have here a con- 
 
 Fig. 10. 
 
 3rd cervical n. 
 
 Phrenic n. 
 
 Line of reflec- 
 tion of peri- 
 cardium. 
 
 Cervicalis ascendens a. 
 Scalenus anticus. 
 Inferior thyroid a. 
 Snperficialis colli a. 
 Phrenic n. 
 Posterior scapular a. 
 
 Supra scapular a. 
 SubclaVian a. 
 Superior intercostal a. 
 Internal mammary a. 
 Pneumogastric n. 
 
 Phrenic n. 
 
 Appendix of left auricle. 
 
 fluence of large veins in front of the artery. The subclavian vein 
 is -situated below the artery, but on a plane anterior to it. Above 
 the artery and to its outer side, are the trunk nerves of the 
 brachial plexus. One of these nerves (the conjoined fifth and 
 
54 SUBCLAVIAN ARTERY. 
 
 sixth cervical) runs so nearly parallel with the artery, and on 
 a plane anterior to it, that it is quite possible to mistake the 
 nerve for the artery, in the operation of tying it. I have heard 
 a hospital surgeon of great experience say, that he had seen this 
 mistake committed three times during life. Behind the artery 
 is the scalenus medius, and below it the first rib. In this part 
 of its course, the artery as a rule gives off no branches ; the most 
 frequent exceptions are the posterior scapular, and supra-sca- 
 pular. 
 
 The left subclavian is the last of the three great branches which 
 
 arise from the arch of the aorta. It ascends nearly 
 
 Left subcla- ver tically out of the chest, and then arches in front of 
 
 vian artery. J 
 
 the apex of the lung and pleura to reach the inner 
 border of the scalenus anticus, behind which it runs over the 
 first rib. 
 
 In the first part of its course, the left subclavian lies deeply in 
 the chest, near the spine. On its left side it is covered by the 
 pleura ; on its right side are the thoracic duct, the oesophagus and 
 the trachea : the pneumogastric, phrenic, and sympathetic nerves, 
 and the left carotid artery runs nearly parallel with it : the left 
 brachio-cephalic vein crosses in front of it. Behind it, is the 
 longus colli muscle and the inferior cervical ganglion. 
 
 Arrived at the level of the upper part of the chest, the left 
 subclavian arches, like the right, over the apex of the lung, and 
 has similar relations namely, in front, it is covered by the sternal 
 end of the clavicle, the sterno-mastoid, sterno-hyoid, and sterno- 
 thyroid muscles, and by the internal jugular and vertebral veins: 
 behind it, are the apex of the lung and the pleura. 
 
 Behind the scalenus anticus, and orr the surface of the first rib, 
 the relations of the left subclavian are similar to those of the right 
 (p. 52). 
 
 The left subclavian, then, differs from the right only in the first 
 part of its course. Now what are these differences ? 
 
 1. The left subclavian comes direct from the arch of the aorta, 
 and is therefore longer, deeper in the chest, and more vertical 
 than the right, which comes from the arteria innominata. 
 
SUBCLAVIAN ARTERY. 55 
 
 2. The left subclavian is in close relation with the oesophagus 
 and the thoracic duct : the right is not. 
 
 3. The left subclavian is crossed by the left brachio-cephalic 
 vein. 
 
 4. The left subclavian has the phrenic, pneumogastric, and sym- 
 pathetic nerves nearly parallel with it ; on the right side, these 
 nerves cross the artery at a nearly right angle. 
 
 5. The left subclavian is not embraced by the recurrent laryu- 
 geal nerve, like the right subclavian. 
 
 The thoracic duct bears an important relation to the left sub- 
 clavian. It ascends from the chest to the left of the oesophagus 
 and behind the artery ; then arches behind the internal jugular 
 vein, and terminates in the subclavian vein at its junction with 
 the jugular. The duct is so thin and transparent that it easily 
 escapes observation ; it is most readily found by raising the sub- 
 clavian vein close to its junction with the jugular, and searching 
 with the handle of the scalpel on the inner side of the scalenus 
 anticus, in front of the vertebral vein. 
 
 Before tracing the branches of the subclavian artery, consider 
 some points relating to the operation of tying it. 
 
 To tie the artery in the first part of its course, namely, on the 
 inner edge of the scalenus anticus, is an operation of great difficulty 
 and danger, even with the parts in a normal position. The great 
 depth at which the artery is placed, the size and close proximity 
 of its numerous branches, the large veins by which it is covered, 
 its connection with the pneumogastric, recurrent laryngeal, phrenic, 
 and sympathetic nerves, and above all its close contiguity with the 
 pleura, form a combination of circumstances so formidable that 
 one cannot be surprised the operation has never been performed 
 with a favourable result. 
 
 In the second part of its course, namely, between the scalene 
 muscles, the artery is more accessible. It would be necessary to 
 divide the clavicular origin of the sterno-mastoid, the cervical 
 fascia, and the scalenus anticus, to reach the vessel ; the phrenic 
 nerve and the subclavian vein would be the chief objects exposed 
 to injury. This operation was performed first and with success by 
 
56 8UBCLAV1AN ARTERY. 
 
 Dupuytren in the year 1819. More recently it has beeji performed 
 by Dr. Warren, of Boston. The patient recovered, though the 
 pleura was wounded."* 
 
 But in the last part of its course, that is, 'on the outer side of 
 the scalenus, the artery may be tied with comparative facility. 
 The incision should be made from three to four inches in length, 
 parallel with the upper border of the clavicle. We divide the 
 platysma, some of the supra-clavicular nerves, and the cervical 
 fascia. The external jugular vein must be drawn to the outer 
 side, or divided and tied at both ends. With the finger and the 
 handle of the scalpel we then make our way down to the outer 
 edge of the scalenus anticus, behind which the artery will be found 
 lying upon the first rib. Remember the tubercle on the inner edge 
 of the rib which indicates the insertion of the scalenus : this 
 tubercle is the best guide to the artery. It will be necessary to 
 divide a layer of fascia which immediately covers the vessel before 
 the needle can be introduced around it. Mr. Ramsden of St. 
 Bartholomew's Hospital was the first who tied the subclavian in 
 the third part of its course, in the year 1809 ; since that time the 
 operation has been repeatedly performed, with most favourable 
 results. 
 
 In the hands of a surgeon possessed of a practical knowledge of 
 anatomy the operation is easy, provided all circumstances be 
 favourable; but circumstances are often very unfavourable. It 
 often happens that the aneurismal or other tumour, on account of 
 which the operation is performed, raises the clavicle beyond its 
 natural level, and so disturbs the parts, that to expose the artery 
 and place a ligature around it becomes exceedingly difficult- 
 Under such circumstances one cannot be surprised that even dis- 
 tinguished anatomists have committed mistakes. Sir Astley 
 Cooperf failed in one instance. Dupuytren perforated the artery 
 with the point of the needle, and included one of the nerves in the 
 ligature : fatal haemorrhage was the result.J I was present at an 
 
 * Med. Chirurg. Trans., vol. xxix. p. 25. 
 
 f London Medical Review, vol. ii. p. 300. 
 
 | Edinburgh Med. and Surg. Journal, vol. xvi. 1820. 
 
BRANCHES OF THE SUBCL AVIAN. 57 
 
 operation in which the large nerve (a branch of the brachial plexus) 
 which runs parallel with and on a plain anterior to the artery was 
 mistaken for it and tied; the surgeon being deceived by the pulsa- 
 tion communicated to the nerve. 
 
 Branches of ^ e t >ranc ^ es f * ne subclavian extend so far, that in 
 the subcla- the present dissection we can trace them only for a short 
 tery * distance. They are four in number : 
 
 1. The vertebral. 
 
 2. The thyroid axis, which gives off the inferior thyroid, supra- 
 scapular, posterior-scapular, and cervicalis ascendens. 
 
 3. The internal mammary. 
 
 4. The superior intercostal, which gives off the deep cer- 
 vical. 
 
 As a rule, three branches are given off from the subclavian in 
 the first part of its course the vertebral, internal mammary, and 
 thyroid axis and one from the second part, the superior inter- 
 costal. The most frequent deviation is, that the posterior scapular 
 (transversalis colli) arises from the subclavian in the third part of 
 its course.* 
 
 This, the first and largest branch, arises from the 
 ll PP er part of the subclavian. For a short distance it 
 lies in the interval between the scalenus anticus and the 
 longus colli. Here it enters the foramen in the transverse process 
 of the sixth cervical vertebra, and ascends through the foramina 
 in the transverse processes of the succeeding vertebras. In the 
 interval between the axis and the atlas, the artery makes a sigmoid 
 curve, that it may not be stretched in the rotation of the head. 
 Having traversed the foramen of the atlas, the artery curves 
 backwards along the groove in its arch, perforates the posterior 
 occipito-allantoid ligament and the dura mater, then enters the 
 skull through the foramen magnum, and unites with its fellow 
 
 * With reference to the origin of the posterior scapular (transversalis colli) artery, 
 I made special observations during the winter session of 1858-59. I found that this 
 artery was given off most frequently, not by the thyroid axis, but by the subclavian 
 in the third part of its course. Under these circumstances the superficialis colli a. 
 generally came from the thyroid axis. 
 
58 BRANCHES OF THE SUBCLAVIAX. 
 
 near the lower border of the pons Varolii,' to fonn the basilar 
 artery. 
 
 The vertebral artery is accompanied by slender nerves from the 
 inferior cervical ganglion of the sympathetic. These nerves com- 
 municate with the spinal nerves forming the brachial plexus. 
 
 Destined for the brain, the vertebral gives off no branches in 
 the neck, except a few small ones to the deeply-seated muscles ; 
 it furnishes, however, to the spinal cord and its membranes small 
 arteries which pass through the intervertebral foramina. 
 
 The vertebral vein is formed by small branches from the muscles 
 near the foramen magnum. It descends in front of the artery 
 through the foramina in the transverse processes, and joins the 
 brachio-cephalic vein. It receives the veins from the cervical 
 portion of the spinal cord. In some subjects it communicates with 
 the lateral sinus by a branch through the posterior condyloid 
 foramen. 
 
 The cervical nerves pass through the intervertebral foramina 
 behind the vertebral artery, so that the artery runs behind its 
 vein, and in front of the nerves. 
 
 The thyroid axis arises from the subclavian near the 
 Thyroid inner edge of the scalenus anticus, and after a course of 
 
 3.X1S. 
 
 a quarter of an inch divides into four branches, which 
 take different directions ; namely, the inferior thyroid, the posterior 
 scapular, the supra-scapular, and the ascending cervical. 
 
 The inferior thyroid artery ascends tortuously behind the 
 sheath of the common carotid and the sympathetic nerve, to the 
 deep surface of the thyroid body, in which it communicates freely 
 with the superior thyroid and with its fellow. It gives small 
 branches to the trachea, the oesophagus, and the larynx. 
 
 The ascending cervical artery usually arises from the inferior 
 thyroid. It ascends close to the spine, between the scalenus 
 anticus and the rectus capitis anticus major, and terminates in 
 small branches, some of which supply these muscles ; others enter 
 the intervertebral foramina, and supply the spinal cord and its 
 membranes. 
 
 The supra-scapular artery (transversalis humeri) runs outwards 
 
BRANCHES OF THE SUBCLAVIAN. 59 
 
 over the scalenus anticus, then directly beneath and parallel with 
 the clavicle; crossing over the third part of the subclavian artery 
 to the superior border of the scapula, it passes above the trans- 
 verse ligament which bridges over the notch, and divides into 
 branches, some of which ramify above, others below, the spine of 
 this bone. It inosculates freely in the infra- spinous fossa with the 
 ' dorsalis scapulae,' a branch of the subscapular, and with the 
 posterior scapular artery. Near the notch, it is joined by the 
 supra-scapular nerve, which runs through it. 
 
 The posterior scapular (transversalis colli) artery, of which the 
 normal origin is said to be from the thyroid axis, very frequently 
 arises from the subclavian in the last part of its course. It is larger 
 than the preceding artery, and runs tortuously across the side of the 
 neck (higher than the supra-scapular), over the scalene muscles 
 and the great nerves of the brachial plexus (sometimes between 
 them), and disappears beneath the trapezius and the levator anguli 
 scapulae to reach the posterior angle of the scapula. It then runs 
 beneath the rhomboid muscles, in which it is lost. In the space 
 between the sterno-inastoid and trapezius, the posterior scapular 
 gives off the ' superficialis colli.' This vessel proceeds tortuously 
 across the posterior triangle of the neck to the under surface of 
 the trapezius, which, with the levator anguli scapulae, it principally 
 supplies. 
 
 The superficialis colli often comes direct from the thyroid axis, 
 when the posterior scapular arises from the last part of the sub- 
 clavian. 
 
 The veins corresponding to the supra-scapular and posterior 
 scapular arteries terminate in the external jugular, sometimes in 
 the subclavian. The middle thyroid vein crosses in front of the 
 common carotid artery, and joins the internal jugular. 
 
 This artery arises from the subclavian opposite to the thyroid 
 
 axis. It enters the chest behind the subclavian vein, 
 
 Internal anc j d escenc i g behind the cartilages of the ribs, about 
 
 mammary. 
 
 half an inch from the sternum. Its further progress 
 will be examined in the dissection of the chest. The correspond- 
 ing vein most frequently terminates in the brachio-cephalic. 
 
60 
 
 BRANCHES OF THE SUBCLAV1AN. 
 
 Fig. 11. 
 
 This artery is given off by the subclavian. behind the 
 Superior scalenus anticus, so that you must divide the muscle to 
 
 intercostal. . , i 
 
 see it. It descends into the chest behind the pleura, 
 passing over the necks of the first and second ribs, and furnishes 
 the arteries of the two upper intercostal spaces. It usually inoscu- 
 lates with the first inter- 
 costal branch of the aorta. 
 The corresponding vein 
 terminates on the right 
 side in the vena azygos ; 
 on the left in the brachio- 
 cephalic. 
 
 This artery 
 
 SrvLl. arises from the 
 superior inter- 
 costal, seldom direct from 
 the subclavian. It goes 
 to the back of the neck 
 between the first rib and 
 the transverse process of 
 the last cervical vertebra, 
 and ascends between the 
 complexus and the semi- 
 spinalis colli, both of which 
 it supplies. It sometimes 
 inosculates with the ( prin- 
 ceps cervicis,' a branch of 
 the occipital a. 
 
 To test your knowledge 
 of the branches of the sub- 
 clavian artery, reflect upon 
 the answer to the follow- 
 ing question : If the ar- 
 tery were tied in the^rs^ part of its course before it gives off any 
 branches, how would the arm be supplied with blood? The 
 answer is, by five collateral channels, as follow : 1. By the corn- 
 
 DIAGRAM TO SHOW THE INOSCULATIONS OF THE 
 SUBCLAVIAN ARTEHY. 
 
BRACHIAL PLEXUS OF XERVES. 61 
 
 munications between the superior and inferior thyroid : 2. By the 
 communication between the two vertebral : 3. By the communi- 
 cations between the internal mammary and the intercostals and 
 the epigastric: 4. By the communications between the thoracic 
 branches of the axillary, and the intercostal branches of the aorta : 
 5. By the communications between the superior intercostal and 
 the aortic intercostal. These inosculations are shown in the 
 diagram, p. 60. 
 
 Again, if the subclavian were tied in the third part of its course, 
 the circulation would be carried on by the communications : 1. 
 Between the supra-scapular and dorsalis scapulaB (branch of sub- 
 scapular): 2. Between the posterior scapular and the subscapular : 
 3. Between the long and short thoracic on the one hand, and the 
 internal mammary and aortic intercostals on the other. 
 
 The subclavian vein does not form an arch like the 
 
 Subclavian . . 
 
 vein. artery, but proceeds in a nearly straight line over the 
 
 first rib to join the internal jugular. Throughout its 
 whole course the vein is situated on a plane anterior to and a little 
 lower than the artery, from which it is separated by the scalenus 
 anticus, the phrenic and pneurnogastric nerves. It has a valve 
 just before its junction with the internal jugular. It receives the 
 anterior jugular, external jugular, and through it the supra- 
 scapular and posterior- scapular veins. 
 
 Brachial ^e ^ ar ^ e nerves forming the plexus which supplies 
 
 plexus the upper extremity are the anterior divisions of the 
 
 of nerves. four lower cervical and the first dorsal. Emerging 
 from the inter vertebral foramina they appear between the anterior 
 and middle scalene muscles, and pass with the subclavian artery 
 into the axilla. To this bundle of nerves the name 'plexus' is 
 given, on account of their mutual communications. The plexus 
 at its root is wide, and situated higher than the subclavian artery, 
 and nearly on the same plane ; but as the plexus descends beneath 
 the clavicle its component nerves converge, and in the axilla, com- 
 pletely surround the artery. 
 
 The plexus is crossed superficially by the omo-hyoid muscle, 
 and by the supra-scapular and posterior scapular arteries. 
 
62 
 
 BRACHIAL PLEXUS OF NERVES. 
 
 The arrangement of the nerves in the formation of the plexus is 
 usually thus : The fifth and sixth cervical unite to form a single 
 cord ; the eighth cervical and the first dorsal form another cord ; 
 
 Fig. 12. 
 
 DIAGRAM OF THE BRACHIAL PLEXUS OF NERVES, AND THEIR RELATION TO THE 
 AXILLARY ARTERY. 
 
 1. Ulnar. 
 
 2. Internal cutaneous. 
 
 3. Lesser int. cutaneous (n. of Wrisberg). 
 
 4. Musculo-spiral. 
 
 6. N. to latissimus dorsi. 
 
 6. N. to teres major. 
 
 7. N. to subscapularis. 
 
 8-9. Anterior thoracic n. to pectoral inusclea. 
 
 10. N. to serratus magnus. 
 
 11. Median. 
 
 12. Circumflex. 
 
 13. External cutaneous. 
 
 14. Supra-scapular. 
 
 15. Posterior scapular. 
 
 the seventh cervical runs for a short distance alone, and then splits 
 into two branches, one of which joins the cord formed by the fifth 
 and sixth cervical, the other, that formed by the eighth cervical 
 
BRANCHES OF THE BRACHIAL PLEXUS. 63 
 
 and first dorsal. The branch joining the trunk formed by the 
 eighth cervical and first dorsal usually receives a large reinforce- 
 ment from the conjoined fifth and sixth cervical. Thus two great 
 trunks are formed, which lie for some distance above and to the 
 outer side of the subclavian artery. Beneath the clavicle, a third 
 cord is formed by the junction of a fasciculus from each of the two 
 primary trunks, so that in the axilla there are three large cords, 
 one external to the axillary artery, one internal to it, the third 
 behind it.* 
 
 The plexus gives off above the clavicle the following nerves : 
 
 a. A branch forming one of the roots of the phrenic arises from 
 the fifth cervical. 
 
 b. Nerve to the subclavius m. This proceeds from the fifth 
 and sixth cervical, and crosses the subclavian artery in the third 
 part of its course. It frequently sends a filament, which passes in 
 front of the subclavian vein to join the phrenic nerve. 
 
 c. Nerves to the scalene and the longus colli muscles are given 
 off from the lower cervical nerves as they leave the intervertebral 
 foramina. 
 
 d. Nerve to the rhomboid muscles. This arises from the fifth 
 and sixth cervical nerves, and accompanies the posterior scapular 
 artery, beneath the levator anguli scapulas, which, as well as the 
 rhomboid muscles, it supplies. 
 
 e. The supra-scapular nerve arises from the cord formed by 
 the fifth, sixth, and seventh cervical n., runs to the upper border 
 of the scapula, where it meets with the corresponding artery, and 
 then passing through the notch in the scapula, terminates in the 
 supra-spinatus and infra-spinatus m. 
 
 /. The nerve (called external respiratory by Sir C. Bell) to the 
 serratus magnus arises from the fifth and sixth cervical, appears 
 between the middle and posterior scalene muscles, then descends 
 behind the plexus and the subclavian vessels to the outer surface 
 of the serratus magnus, to which it is exclusively distributed. 
 
 * This seems, from a number of dissections, to be the most frequent arrangement of 
 the nerves forming the brachial plexus. This arrangement is, however, very variable, 
 often differing on the two sides in the same subject. 
 
64 MUSCLES OF THE FACE. 
 
 It only remains to be observed that the upper cord of the 
 brachial plexus receives a branch from the lower com of the cer- 
 vical, and that each of its component nerves communicate by 
 slender filaments with the sympathetic system. 
 
 Below the clavicle the plexus divides into branches for the 
 supply of the arm ; namely, the anterior thoracic nerves (two in 
 number, to the pectoralis major and minor), the subscapular (three 
 in number, to the subscapularis, the latissimus dorsi, and teres 
 major), the circumflex ^to the deltoid and teres minor), the 
 median, the musculo-spiral, the ulnar, the external cutaneous, 
 the internal cutaneous, and the lesser internal cutaneous (nerve of 
 Wrisberg). 
 
 DISSECTION OF THE FACE. 
 
 Much practice is required to make a good dissection of the face. 
 The muscles of expression are numerous and complicated ; they 
 are interwoven with the subcutaneous tissue and closely united to 
 the skin : their fibres are often pale and indistinct. The face is 
 amply supplied with motor and sensitive nerves, of which the 
 ramifications extend far and wide. Therefore you must not be 
 discouraged, if in a first attempt you fail to make a satisfactory 
 display of the parts. 
 
 The cheeks and nostrils should be distended with horsehair, 
 and the lips sewn together. 
 
 Make an incision down the mesial line of the face ; another 
 from the chin along the base of the lower jaw to the angle, then 
 prolong it in front of the ear to the zygoma. Eeflect the skin 
 from below upwards. Each muscle as it is cleaned must be put 
 on the stretch by hooks. 
 
 The nerve which supplies all the muscles of the face is the 
 ' portio dura? or facial division of the seventh cerebral nerve. It 
 emerges from the stylo-mastoid foramen, and divides into branches, 
 which pass through the parotid gland, forming a plexus termed 
 the ' pes anserinus.' 
 
 The sensitive nerves of the face are supplied by the three 
 
MUSCLES OF THE FACE. 65 
 
 divisions of the fifth cerebral nerve ; namely, the supra-orbital, 
 the infra-orbital, and the mental. No other nerve takes any share 
 in conferring sensation upon the face except the auriculo-parotidean 
 branch of the cervical plexus (p. 16), which supplies the skin 
 covering the parotid gland and part of the cheek. 
 
 The skin covering the cartilages of the nose is supplied by a 
 small nerve called the naso-lobular. It is the terminal branch of 
 the nasal division of the ophthalmic nerve. It appears between 
 the bone and the cartilage, lying under the compressor naris in. 
 Musculus This muscle arises from the fascia over the masseter 
 
 risorius m., arid passes forwards to be inserted into the angle of 
 (Santorim). ^ mou tjj 5 w here it intermingles with the orbicularis 
 oris and other muscles in this situation. It produces the smile, 
 not of good humour, but of derision. 
 
 It is convenient to arrange the muscles of the face under three 
 heads ; appertaining respectively to the mouth, the nose, the eye- 
 brows and lids. Begin with those of the mouth. 
 
 The muscles of the mouth are arranged thus : there is an orbi- 
 cular or sphincter muscle surrounding the lips ; from this, as from 
 a common centre, muscles diverge and are fixed into the surround- 
 ing bones. They are named elevators, depressors, &c., according 
 to their respective action. 
 
 This muscle, nearly an inch in breadth, surrounds 
 r icu ans ^ j^^fo. j^-g s j ze an( j thickness in different indi- 
 
 O11S. 
 
 viduals, produce the variety in the prominence of the 
 lips. Observe that its fibres do not surround the mouth in one 
 unbroken series (excepting a thin fasciculus which is said to pass 
 around the free margin of the lips), but that those of the upper 
 and lower lip decussate at the angles of the mouth, and inter- 
 mingle with the fibres of the buccinator and other muscles which 
 converge from different parts of the face. The cutaneous surface 
 of the muscle is intimately connected with the lips and the sur- 
 rounding skin ; the deep surface is separated from the mucous 
 membrane by the labial glands and the coronary vessels. 
 
 The ' orbicularis ' is the antaonist of all the muscles which 
 
66 MUSCLES OF THE FACE. 
 
 move the lips. Upon a nice balance of their opposite actions 
 depends the play of the mouth.* 
 
 This muscle arises from the oblique line of the lower 
 Depressor . ] :)e i ow the foramen mentale, and is inserted into 
 
 anguli ons. J 7 
 
 the angle of the mouth, intermingling with the zygo- 
 matic muscles. It is an important muscle in the expression of 
 sorrowful emotions. We see its action when children cry. 
 
 This muscle arises from the oblique line of the 
 
 infer?o S ris%r " lower jaw, and is inserted into the lower lip. It 
 
 quadratus covers the vessels and nerves which come through 
 
 the foramen mentale. It must therefore be divided 
 
 in cutting through the nerve in cases of neuralgia. 
 
 This muscle arises from the lower jaw below the 
 incisor teeth, and is inserted into the skin of the chin. 
 To see it properly, evert the lower lip and remove the 
 mucous membrane on either side of the frsenum. There are two 
 of them, one for each side. Their action is well shown when we 
 shave. 
 
 Zygomati- ^ ne ^* ma j or arises from the outer surface of the 
 cus major malar bone, passes obliquely downwards and is inserted 
 into the angle of the mouth, joining the depressor 
 anguli oris. The Z. minor arises from the outer surface of the 
 malar bone, in front of the preceding, and is inserted into the 
 angle of the mouth, joining the levator labii superioris. The 
 action of the zygomatici is seen in laughing. 
 
 Before examining the orbicularis palpebrarum, notice the tendo 
 oculi. To make the tendon more apparent the tarsal cartilages 
 should be drawn outwards. 
 
 This tendon is about two linesf in length, and is 
 readily felt at -the inner angle of the eye by drawing 
 
 * In strong muscular lips the upper part of the orbicularis sends a small sub- 
 cutaneous slip of muscle from each side along the septum nasi nearly to the apex. 
 The interval between the two slips corresponds to the furrow which leads from the 
 nose to the lip. This is the ' naso-labialis' or 'depressor septi narium' of Haller 
 and Albinus. 
 
 f A line is the twelfth part of an inch. 
 
MUSCLES OF THE FACE. 67 
 
 the eyelids outwards. It is fixed to the nasal process of the supe- 
 rior maxillary bone, in front of the lachrymal groove, passes out- 
 wards, and divides into two portions, one of which is attached to 
 the upper, the other to the lower tarsal cartilage. The tendon 
 crosses the lachrymal sac a little above the centre, and furnishes a 
 tendinous expansion which covers the sac and is attached to the 
 margin of the bony groove. To see this expansion we must reflect 
 that portion of the orbicularis palpebramm which covers the sac. 
 
 In puncturing the lachrymal sac the knife is introduced below 
 the tendon, in a direction downwards, outwards, and a little back- 
 wards. We have to divide the skin, a few fibres of the orbicularis, 
 and the fibrous expansion from the tendo oculi. The angular 
 artery and vein are situated on the inner side of the incision. 
 
 This muscle arises from the tendo oculi, from the 
 nasal process of the superior maxillary bone, and from 
 the internal angular process of the frontal; it is in- 
 serted into the skin of the brow, temple, and cheek. 
 
 This broad sphincter muscle surrounds the margin of the orbit 
 and eyelids, and its fibres are divided into two portions, an 
 external or orbital and an inner or palpebral. Its orbital fibres 
 take a wide sweep, passing uninterruptedly around the orbit, and 
 mingle on the forehead with the occipito-frontalis ; on. the cheek 
 with the zygomaticus minor, and the levator labii superioris. 
 
 The fibres which belong to the eyelids (orbicularis palpebrarum) 
 are thin and pale. They arise from the tendo oculi, and form, 
 over each eyelid, a series of elliptical curves which meet at the 
 external canthus of the lids, and are attached to the external 
 tarsal ligament and malar bone. The degree of their curvature 
 becomes less as they approach the margin of the lids, so that some 
 fibres proceed close to the lashes. This was first pointed out by 
 Eiolanus,* and described as the ' musculus ciliaris.' f 
 
 * Anthropologia, lib. v. cap. 10. 
 
 t Strictly speaking the ciliary muscle arises from the two little divisions of the 
 tendo oculi, and is inserted, at the external canthus, into the fibrous tissue which 
 unites the two tarsal cartilages. 
 
 V -2 
 
68 STRUCTURE OF THE EYELIDS. 
 
 No fat is ever found on the eyelids ; nothing intervenes between 
 the skin and the muscle but loose areolar tissue, that there may 
 be no impediment to the free play of the lids. 
 
 The orbicular muscle not only shuts the eye but protects it. 
 When the eye is threatened by a blow, the muscle suddenly con- 
 tracts, presses the eye back into the orbit, and contracts the skin 
 of the brow and cheek so as to form a soft cushion in front of the 
 orbit. The cushion itself may be severely bruised, as is seen in a 
 ' black eye ' ; but the globe itself is rarely injured. When the 
 eye is closed, as in winking, the palpebral portion of the muscle 
 contracts. Observe this movement attentively, and see that the 
 lids are drawn slightly inwards as well as closed. The object of 
 this inward motion is to direct the tears towards the inner angle 
 of the eyelids, where they are absorbed by the puncta lachry- 
 malia. 
 
 Since the orbicular muscle is supplied by the facial nerve, it is 
 affected in facial palsy, and the patient cannot shut the eye. 
 
 This arises from the superciliary ridge of the frontal 
 supercilii r bone, passes outwards, and is inserted into the under 
 surface of the orbicularis oculi. It lies concealed be- 
 neath the orbicularis, and is the proper muscle of frowning. 
 
 This is situated on the bridge of the nose, on each 
 nash s ^ e f the m esial line, and is regarded as a prolonga- 
 
 tion of the occipito-frontalis. It mingles with the 
 fibres of the compressor nasi, and its action is to elevate the skin 
 of the nose, as in the expression of surprise. 
 
 The present being a good opportunity to examine the structure 
 of the eyelids, postpone for the present the dissection of the re- 
 maining muscles of the face. 
 
 STKUCTURE OF THE EYELIDS. The eyelids are composed of dif- 
 ferent tissues arranged in successive strata one beneath the other. 
 There are 1, the skin; 2, the orbicularis palpebrarum ; 3, the 
 expanded tendon of the levator palpebrae (in the upper lid only) : 
 4, the tarsal cartilage and the palpebral ligament which extends 
 from the margin of the orbit to the inner free margins of these 
 cartilages ; 5, Meibomian glands ; 6, mucous membrane. These 
 
STRUCTURE OF THE EYELIDS. 69 
 
 structures are separated by areolar tissue, which for good reasons 
 never contains fat. 
 
 The skin of the eyelids is remarkably smooth and delicate. It 
 is abundantly supplied with sensitive nerves by branches of the 
 fifth pair namely, by the supra-orbital, supra-trochlear, infra- 
 trochlear, lachrymal, and infra-orbital nerves. 
 
 The orbicularis palpebrarum has been already described (p. 67). 
 It is supplied with nerves by the facial. 
 
 The levator palpebrce arises from the back of the orbit, gradually 
 becomes broader, and terminates in a thin aponeurosis, which 
 unites with the broad tarsal ligament, and is lost on the upper 
 surface of the superior tarsal cartilage. 
 
 T , These are plates of fibro-cartilage which support and 
 
 tilages and give figure to the eyelids. There is one for each lid, 
 ligaments. an( j ^ ev are cormec t e d at the angles (commissures or 
 canthi) of the lids through the medium of fibrous tissue. One can 
 best examine them by everting the lids. Each cartilage resembles 
 its lid in form. The upper is the larger, is broad in the middle, 
 and gradually becomes narrower at either end. The lower is 
 nearly of uniform breadth throughout. Both are thicker on the 
 nasal than the temporal side. They are connected to the margin 
 of the orbit, and maintained in position by the tendo oculi, and 
 by what are called the broad tarsal or palpebral ligaments : these 
 ligaments are continuations from the periosteum of the orbit to the 
 tarsal cartilages. There are two of them, termed upper and lower, 
 and proceeding to each cartilage respectively. When an abscess 
 forms in the areolar tissue of the lids, these ligaments prevent the 
 matter from making its way into the orbit. 
 
 Each tarsal cartilage is moreover attached to the malar bone, by 
 means of a ligament, called the external tarsal ligament. 
 
 The ciliary margin is the thickest part of the tarsal cartilages. 
 It is generally stated that the inner edge of each is sloped or 
 beveled off; and that, when the lids are closed, there is formed, 
 with the globe of the eye, a triangular channel. This channel is 
 said to conduct the tears to the puncta lacrymalia. According to 
 our observation, this channel does not exist : for when the lids are 
 
70 
 
 STRUCTURE OF THE EYELIDS. 
 
 Fig. 13. 
 
 closed, their margins are in such accurate apposition, Jbh at not the 
 slightest interstice can be discovered between them. 
 
 The puncta lacrymalia are two pin-holes apertures, easily dis- 
 covered on the margin of the lids, close to the inner angle. They 
 are the orifices of the canals, called canaliculi, which pass 
 inwards, and convey the tears into the lachrymal sac. Observe 
 that their orifices are directed backwards. In facial palsy, the 
 tensor tarsi being affected, the puncta lose their proper direction, 
 and the tears flow over the cheek. 
 
 In the introduction of probes for the purpose of opening the 
 contracted puncta, or of slitting up the lachrymal duct, it is 
 necessary to know the exact direction of these tubes. (See diagram.) 
 
 By passing a bristle into one of 
 them, we find that it does not run 
 straight from the punctum to the 
 sac, but that it proceeds for a short 
 distance perpendicularly, and then, 
 dilating into a small pouch, makes 
 a sharp bend inwards to the la- 
 chrymal sac. In the majority of 
 cases, the tubes open into the sac 
 by a common orifice. When, from 
 any cause, the tears are secreted 
 in greater quantity than usual, they 
 overflow and trickl e d own the cheek. 
 
 The eyelashes (cilia) are planted in two or more rows along the 
 edge of the tarsal cartilages. The eyelashes of the upper lid are 
 longer and more numerous than in the lower ; and their convexity 
 is directed downwards, while those of the lower lid have an 
 opposite curve. The bulbs of the lashes are situated between the 
 tarsal cartilage and the fibres of the ciliary muscle. They are 
 supplied with blood by the palpebral branches of the ophthalmic, 
 which run parallel and close to the free borders of the lids under 
 the ciliary muscle. 
 
 These sebaceous glands, so called after the anatomist * who first 
 
 * H. Meibom, De vasis palpebrarum novis. Helmstedt, 1666. 
 
STRUCTURE OF THE EYELIDS. 7 1 
 
 described them, are situated on the under surface of 
 
 each of the tarsal cartila g es - In the u PP er Hd there are 
 about thirty ; not so many in the lower. On everting 
 the lid, they are seen running in longitudinal rows in grooves of 
 the cartilage. Under the microscope, one sees that they consist of 
 a central tube, round the sides of which are a number of openings 
 leading to short csecal dilatations. The orifices of these glands are 
 situated on the free margin of the lid behind the lashes. Their 
 use is to secrete an unctuous substance, which prevents the lids 
 from sticking together. 
 
 This name is given to a small reddish body situated 
 lacrymalis a ^ ^ e i nner corner of the eye. It is composed of an 
 aggregation of sebaceous glands covered by mucous 
 membrane. In some instances minute hairs grow upon it. Its 
 use is, probably, to support the inner junction of the eyelids. 
 When the caruncle is diminished in size by disease, the puncta 
 lacrymalia become displaced, and the tears run down the 
 cheek. 
 
 External to the caruncula lacrymalis is a slight vertical fold of 
 conjunctiva, 'plica semilunaris,' which is by some considered to 
 be a rudimentary membrana nictitans (third eyelid found in 
 birds). 
 
 The conjunctival coat of the eyelid will be described with the 
 anatomy of the eye. Observe at present, that it is more vascular 
 than the conjunctival coat of the eye, and that it presents a 
 number of minute papillae, which, when enlarged and aggre- 
 gated by inflammation, give rise to the disease called ' granular 
 lids.' 
 
 Such, in outline, is the structure of the eyelids. Their use is 
 best described by Socrates, who, in answer to the question whether 
 animals were made by chance or design, replies: ' Think you 
 not that it looks like the work of prescience, because the sight is 
 delicate, to have guarded it with eyelids, which open when we 
 want to see, but shut when we go to sleep ; to have fenced these 
 lids with eyelashes, which, like a sieve, strain the dusty wind, and 
 hinder it from hurting the eyes ; and over the eyes to have placed 
 
72 MUSCLES OF THE FACE. 
 
 eyebrows, as eaves, to carry off the sweat of the bro^w from dis- 
 turbing the sight ? ' * 
 
 The dissection of the muscles of the face must now be continued. 
 In order to see the origin of the elevators of the upper lip and 
 nose, the lower circumference of the orbicularis oculi must be 
 raised. 
 
 Levatorlabii ^^ ar ^ ses from the superior maxillary bone near 
 superioris its orbital margin, and passing downwards divides into 
 alseque nasi. two p Or ti O ns, an inner inserted into the side of the 
 nose, an outer into the upper lip. It acts chiefly in expressing 
 the smile of derision, and the scornful affections of the mind. 
 Its habitual use occasions corresponding permanent folds in the 
 skin, which are, to a certain extent, indicative of the feelings 
 and passions. 
 
 This arises from the lower margin of the orbit above 
 superioris. the infra-orbital foramen, and is inserted into the 
 
 upper lip. It is nearly an inch in breadth at its origin, 
 and it covers the infra-orbital vessels and nerves. 
 
 This muscle, which is covered by the levator labii 
 aneuHoris superioris, arises from the canine fossa of the superior 
 
 maxilla, below the infra-orbital foramen, and is inserted 
 into the angle of the mouth, superficial to the buccinator, its fibres 
 blending with those of the orbicularis oris, zygomatici, and de- 
 pressor anguli oris. 
 
 Two muscles belonging to the nose must now be examined 
 the triangularis or compressor nasi, and the depressor labii supe- 
 rioris 
 
 This muscle is triangular, and arises by its apex from 
 
 the superior maxillary bone, internal to the canine 
 
 fossa, and is attached by a broad thin aponeurosis which 
 spreads over the dorsum of the nose and joins its fellow. The 
 
 * Xenophon's Memorabilia, b. I.e. iv. : Ov 5o/cel <rot Ka\ r6$e irpovoias cpyy eoi/ce 
 rb, eirel a.ff6ei>r)s /J.4v fcrnv ?j otyis, )8Ae<|>apoiS avryv 
 a.va.ireTa.vvvTO.1, eV Se T&> tf/n>&j (Tiry/cAeieTcu ; ws 5' 
 
 &\}>api8as e/i<f>C<rar o<pp6ffi re airoyeKruffai TO. virep TUJV o/ji/j.dTuv a>y /xTjS' 6 (K rrjs 
 tfpcas Kanovpyfj- 
 
MUSCLES OF THE FACE. 73 
 
 origin of this muscle is concealed by the levator labii superioris 
 alseque nasi. 
 
 This arises from the superior maxilla, above the 
 SSTir*- secon d incisor tooth, and is inserted into the septum 
 rioris or de- and ala of the nose. It is situated between the mucous 
 nasi S r alSG membrane and the muscular structure of the upper lip. 
 To expose it, the upper lip must be everted and the 
 mucous membrane removed. 
 
 Besides the muscles above described, we find, in connection 
 with the cartilages of the ala of the nose, pale muscular fibres, in 
 which no definite arrangement can be traced. They constitute the 
 ' dilatator narium anterior' and the 'dilatator narium posterior ' 
 of some anatomists. By acting upon the cartilages of the nose, 
 these little muscles contribute in some degree to express the con- 
 dition of the mind. Some of them dilate the nostrils ; for instance, 
 in dyspnoea : others contract them, as in smelling. 
 
 The buccinator arises from the alveolar borders of 
 
 .Buccinator. . , 
 
 the upper and lower jaws, corresponding to the molar 
 teeth, and from the pterygo-maxillary ligament. The fibres 
 pass forwards and are inserted into the angle of the mouth and 
 the muscular structure of the lips ; the central fibres decussate, 
 i.e. the lower fibres pass upwards along the upper lip, and the 
 upper fibres pass downwards along the lower lip. 
 
 The buccinator is the great muscle of the cheek. It forms with 
 the superior constrictor of the pharynx, a continuous muscular 
 wall for the side of the mouth and pharynx. The bond of connec- 
 tion between the buccinator and the superior constrictor, is the 
 * so-called ' pterygo-maxillary ligament. Now this ligament (see 
 diagram) extends from the hamular process vertically to the pos- 
 terior extremity of the mylo-hyoid ridge of the lower jaw near the 
 last molar. To call it a ligament seems a misnomer : it is simply 
 a fibrous intersection between the two muscles. 
 
 The duct of the parotid gland passes obliquely through the 
 buccinator into the mouth, opposite the second moTar of the upper 
 jaw. 
 
 The chief use of the buccinator is to keep the food between the 
 
74 
 
 MUSCLES OF THE FACE. 
 
 teeth during mastication. It can also widen the mouth. Its 
 power of expelling air from the mouth, as in whistling or playing 
 on a wind instrument, has given rise to its peculiar name. It is 
 
 Fig. 14. 
 
 Orbicularis oris . 
 
 Pterygo-maxillary 
 
 ligament. . . 
 
 Mylo-hyoideus . 
 
 Os-hyoides . . . 
 Thyro-hyoid liga- 
 ment . . . . 
 
 Pomum Adami 
 
 Cricoid cartilage , 
 Trachea . , , 
 
 Glosso-pharyngeal n. 
 Stylo-pharyngeus. 
 
 Superior laryngeal 
 n. and a. 
 
 External laryngeal n. 
 Crico-thyroid. 
 
 Inferior laryngeal n. 
 (Esophagus. 
 
 MUSCLES OF THE PHARYNX. 
 
 supplied by the facial nerve, and is, therefore, affected in facial 
 paralysis. 
 
 The buccinator muscle is covered by a layer of fibrous 
 fascia. tissue, which adheres closely to its surface, and is at- 
 
 tached to the alveolar border of the upper and lower 
 
ARTEKIES OF THE FACE. 75 
 
 jaw. This structure is thin over the anterior part of the muscle, 
 but more dense behind, where it is continuous with the aponeurosis 
 of the pharynx. It is called the * bucco-pharyngeal ' fascia, since 
 it supports and strengthens the muscular walls of these cavities. 
 In consequence of the resistance of this fascia, abscesses do not 
 readily burst into the mouth or the pharynx. 
 
 The molar glands, three or four in number, situated 
 immediately outside the posterior part of the bucci- 
 nator, are about the size of a split pea, and their 
 secretion is conveyed to the mouth by separate ducts near the last 
 molar teeth. 
 
 Between the buccinator and the masseter there is in almost all 
 subjects an accumulation of fat. It is found, beneath the zygoma 
 especially, in large round masses, and may be turned out with the 
 handle of the scalpel. It fills up the zygomatic fossa, and being 
 soft and elastic, does not present the least obstacle to the free 
 movements of the jaw. Its absorption in emaciated individuals 
 occasions the sinking of the cheek. 
 
 The facial (external maxillary) artery is the third 
 Facial branch of the external carotid. It runs tortuously be- 
 
 artery. J 
 
 neath the hypoglossal nerve, the posterior belly of the 
 digastricus, and the stylo-hyoideus, next through the substance of 
 the submaxillary gland, and mounts over the base of the jaw at 
 the anterior edge of the masseter muscle. Up to this point we 
 traced it in the dissection of the neck (page 38). It now ascends 
 tortuously near the corner of the mouth and the ala of the nose, 
 towards the inner angle of the eye, where, much diminished in 
 size, it inosculates with the terminal branch of the ophthalmic, a 
 branch of the internal carotid. In the first part of its course, the 
 facial artery is covered only by the platysma ; above the corner of 
 the mouth it is crossed by a few fibres of the orbicularis oris and 
 the zygomatici ; still higher it is covered by some of the fibres of 
 the elevators of the upper lip and the nose. It lies successively 
 upon the buccinator, levator anguli oris, and levator labii superioris 
 muscles. In its course along the face it gives off the following 
 branches : 
 
76 ARTERIES OF THE FACE. 
 
 a. The inferior labial artery passes inwards voider the de- 
 pressor anguli oris and inosculates with the mental branch of the 
 inferior dental and the inferior coronary artery. 
 
 b. The inferior coronary artery comes off near the angle of the 
 mouth, runs tortuousjy along the lower lip, between the mucous 
 membrane and the orbicularis muscle, and inosculates with its 
 fellow. 
 
 c. The superior coronary proceeds along the upper lip close to 
 the mucous membrane, and inosculates with its fellow ; thus a 
 complete arterial circle is formed round the mouth. These arteries 
 can be felt pulsating on the inner side of the lip, near the free 
 border. From this circle numerous branches pass off to the 
 papillaB of the lips, and the labial glands. The superior coronary 
 gives off a small branch (artery of the septum) which ascends 
 along the septum to the apex of the nose. 
 
 d. The lateral artery of the nose, a branch of considerable size, 
 arises opposite the ala nasi, ramifies upon the external surface of 
 the nose, arid inosculates with the nasal branch of the ophthalmic 
 artery. 
 
 e. The angular artery, which may be regarded as the termina- 
 tion of the facial, inosculates on the inner side of the tendo oculi 
 with the ophthalmic. 
 
 The facial artery supplies numerous branches to the muscles of 
 the face, and inosculates with the trans versalis faciei, infra-orbital, 
 and mental arteries. 
 
 The facial artery and its branches are surrounded by a minute 
 plexus of nerves (nervi molles), invisible to the naked eye. They 
 are derived from the superior cervical ganglion of the sympa- 
 thetic, and exert a powerful influence over the contraction and 
 dilatation of the capillary vessels, and thus occasion those sudden 
 changes in the countenance indicative of certain mental emotions, 
 e. g. blushing or sudden paleness.* 
 
 * M. Bernard and Brown Sequart have proved by experiment that if the branches 
 of the sympathetic, which accompany the facial artery, be divided, the capillary 
 vessels of the face, being deprived of their contractile power, become immediately 
 distended with blood, and the temperature of the face is raised. 
 
PAROTID GLAND. 77 
 
 The facial vein does not run with the artery, but takes a 
 straight course from the inner angle of the eye to the anterior 
 edge of the masseter. In this course it descends beneath tbejzygp- 
 matic muscles, over the termination of the parotid duct, and at 
 the anterior border of the masseter passes over the jaw, behind the 
 facial artery, and joins the internal jugular. 
 
 The facial vein is a continuation of the frontal, which descends 
 over the forehead, and, after receiving the supra-orbital, takes the 
 name of angular at the corner of the eye. It communicates with 
 the .ophthalmic vein, receives the veins of the eyelids, the external 
 parts of the nose, the coronary veins, and others from the muscles 
 of the face. Near the angle of the mouth it is often increased in 
 size by a large vein which comes from a venous plexus deeply 
 seated behind the superior maxillary bone. 
 
 This artery arises from the temporal or the external 
 transversa- carotid in the substance of the parotid gland. It runs 
 forwards across the masseter above the parotid duct, 
 and is distributed to the glandula socia parotidis, and the masseter. 
 It anastomoses with the infra-orbital and facial. It is seldom of 
 large size, except when it supplies those parts which usually 
 receive blood from the facial. We have seen it as large as a 
 goose-quill, furnishing the coronary and the nasal arteries ; the 
 facial itself not being larger than a sewing thread. 
 
 Your attention must now be directed to the parotid gland ; its 
 boundaries, its deep relations, the course of its duct, and the 
 objects contained within the gland. 
 
 The parotid, the largest of the salivary glands, oc- 
 gland! cupies the space between the ramus of the jaw and the 
 
 mastoid process. It is .bounded above by the zygoma ; 
 below by the sterno-mastoid, and digastric muscles ; behind by the 
 meatus auditorius and the mastoid process ; in front, it lies over 
 the ascending ramus of the jaw, and is prolonged for some dis- 
 tance over the masseter. It is separated from the submaxillary 
 gland by the stylo-maxillary ligament ; sometimes the two glands 
 are directly continuous. 
 
 The superficial surface of the gland is flat, and covered by a 
 
78 PAROTID GLAND. 
 
 strong layer of fascia, a continuation of the cervical. * It not only 
 envelopes the gland, but sends down numerous partitions which 
 form a framework for its lobes. The density of this sheath ex- 
 plains the pain caused by inflammation of the gland, the tardi- 
 ness with which abscesses within it make their way to the surface, 
 and the propriety of an early opening. 
 
 The deep surface of the gland is irregular, and moulded upon 
 the subjacent parts. Thus, it passes inwards between the neck of 
 the jaw and the internal lateral ligament; it extends upwards and 
 occupies the posterior part of the glenoid cavity ; below, it reaches 
 the styloid process, and sometimes penetrates deep enough to 
 touch the internal jugular vein. 
 
 That portion of the gland which lies on the masseter muscle is 
 called ' glandula soda parotidis.' It varies in size in different 
 subjects ; and is situated chiefly above the parotid duct, into which 
 it pours its secretion by one or two smaller ducts. 
 
 The duct of the parotid gland (ductus Stenonis *) is thick and 
 strong, and about two inches long. In this respect it differs from 
 the duct of the submaxillary gland, which is less exposed to in- 
 jury. It runs transversely forwards over the masseter, about an 
 inch below the zygoma, perforates the buccinator obliquely, and 
 opens into the mouth opposite the second molar tooth of the upper 
 jaw. Near its termination it is crossed by the zygomaticus major 
 and the facial vein. After perforating the buccinator, the duct 
 passes for a short distance between the muscle and the mucous 
 membrane. Its orifice is small and contracted compared with the 
 diameter of the rest of the duct, which will admit a crow-quill ; it 
 is not easily found in the mouth, being concealed by a fold of 
 mucous membrane. 
 
 Since it is desirable, in operations about the face, to avoid in- 
 juring the parotid duct, it is well to know that the precise direc- 
 tion of the duct corresponds with a line drawn from the middle of 
 Jhe lobule of the ear to a point midway between the nose and the 
 upper lip. 
 
 * Nic. Steno, DC glandulis oris, &c. Lugd. Bat. 1661. 
 
PAROTID GLAND. 79 
 
 On cutting into the substance of the parotid gland, the follow- 
 ing objects are seen in its interior, proceeding in the order of 
 their depth from the surface : 
 
 1. Two or more small absorbent glands. 
 
 2. The *pes anserinus,' or primary branches of the facial 
 nerve. 
 
 3. Branches from the auriculo-parotidean and temporo-auricular 
 nerves which communicate here with the facial. 
 
 4. The external jugular vein formed by the junction of the 
 internal maxillary and temporal veins. 
 
 5. The external carotid, which, after giving many branches to 
 the gland, divides opposite the neck of the jaw, into the internal 
 maxillary and temporal arteries.* 
 
 The absorbent glands about the parotid deserve notice, because 
 they are liable to become enlarged, and simulate disease of the 
 parotid itself. An absorbent gland lies close to the root of the 
 zygoma, in front of the cartilage of the ear ; this gland is some- 
 times affected in disease of the external tunics of the eye ; e.g. 
 in purulent ophthalmia : also in affections of the scalp. 
 
 To display the plexus of nerves (pes anserinus), formed by the 
 branches of the facial in the parotid gland, find one of the larger 
 branches, say one of the malar, on the face, and trace this into 
 the substance of the gland, as a clue to the others, 
 p . , This is the motor nerve of the face. It supplies all 
 
 or facial the muscles of expression, except those which move the 
 eyes. It arises immediately below the ' pons Varolii,' 
 from the lateral tract of the medulla oblongata. The nerve enters 
 the meatus auditorius internus, lying upon the auditory nerve, 
 traverses a tortuous bony canal (aqueductus Fallopii) in the 
 
 * Reviewing the intricate and deep connections of the parotid gland, one cannot 
 but conclude that it is almost, if not quite, impracticable to remove it entirely during 
 life. If this conclusion be correct, even in the normal condition of the gland, what 
 must it be when the gland is enlarged by disease ? John Bell, however, relates a 
 case in which he was induced to attempt the extirpation of a diseased parotid (Prin- 
 ciples of Surgery, vol. iii. p. 262). Other surgeons, too, of more modern date, have 
 attempted the same thing. It is not unlikely that they haA*e mistaken a tumour in 
 the substance of the parotid for disease of the parotid itself. 
 
80 SERVES OF THE FACE. 
 
 petrous portion of the temporal bone, and leaves the^skull at the 
 stylo-mastoid foramen. Its course and connections in the tem- 
 poral bone will be investigated hereafter: at present we must 
 trace the facial part of the nerve. 
 
 Having emerged from the stylo-mastoid foramen, the nerve 
 enters the parotid gland, and soon divides into two primary 
 branches, named, from their distribution, temporo-facial and 
 cervico-facial. These primary branches cross over the external 
 carotid, and the external jugular vein, and form, by their com- 
 munications within the substance of the parotid, the plexus called 
 s pes anserinus,' from its resemblance to the skeleton of a goose's 
 foot. The plexus and the direction of its ramifications must be 
 carefully made out, for you may have to remove tumours formed 
 in the interior of the parotid ; you may find the nerves spread 
 over the tumour, and you must dissect between the nerves without 
 injuring them. 
 
 Close to the stylo-mastoid foramen, the facial nerve sends off its 
 posterior auricular branch (p. 3), which ascends behind the ear 
 and supplies the retrahens and attollens aurem m. and the pos- 
 terior belly of the occipito-frontalis ; it also gives off a branch to 
 the posterior belly of the digastricus and another to the stylo- 
 hyoideus. In this situation it communicates by filaments with 
 the glosso-pharyngeal, pneumogastric, and auriculo-parotidean 
 nerves. 
 
 The -temporo-facial division crosses the external carotid and the 
 neck of the jaw, receives two or more communications from the 
 temporo-auricular (branch of the fifth), and subdivides into tem- 
 poral, malar, and infra-orbital branches. 
 
 The temporal branches ascend over the zygoma, supply the 
 frontalis, the attrahens aurem, the orbicularis palpebrarum, the 
 corrugator supercilii, and tensor tarsi, and communicate with fila- 
 ments of the supra-orbital nerve. 
 
 The malar branches cross the malar bone, supply the orbicularis 
 oculi, and communicate with filaments of the lacrymal and superior 
 maxillary nerves. 
 
 The infra-orbital branches proceed transversely forwards beneath 
 
NERVES OF THE FACE. 81 
 
 the zygomatici over the masseter, and supply the elevators of the 
 upper lip and the muscles of the nose. Beneath the levator labii 
 superioris we find a free communication with the infra-orbital 
 branches of the superior maxillary nerve (second division of the 
 fifth). 
 
 The cervico-facial division, joined by filaments from the 
 auriculo-parotidean (branch of cervical plexus), descends towards 
 the angle of the jaw, and subdivides into buccal, supra- and infra- 
 maxillary branches. 
 
 The buccal branches pass forwards over the masseter parallel 
 with the parotid duct, and supply the buccinator : they communi- 
 cate with the buccal branch of the inferior maxillary nerve (second 
 division of the fifth). 
 
 The supra-maxillary branches advance over the masseter and 
 facial artery, and run under the depressor muscles of the lower lip, 
 all of which they supply. Some of the filaments communicate 
 with the mental branch of the dental nerve. 
 
 The infra-maxillary or cervical branches, one or more in 
 number, were dissected with the neck (p. 17). They arch for- 
 wards below the jaw, covered by the platysma, and communicate 
 with the superficialis colli (branch of the cervical plexus). 
 
 Kespecting the function of the facial nerve, it is necessary to 
 remember that though at its origin it is purely a motor nerve, yet 
 after leaving the stylo-mastoid foramen it becomes a compound 
 nerve, in consequence of the filaments which it receives from the 
 temporo-auricular branch of the fifth, and from the auriculo-paro- 
 tidean branch of the cervical plexus. These communications ex- 
 plain the pain which is often felt in facial paralysis along the track 
 of the facial nerves. 
 
 Sensitive These are the supra-orbital, the infra-orbital, and the 
 
 nerves of mental, all branches of the fifth pair. 
 the face. rpj^ W |j W Yj_0 r &# a J nerve is a branch of the first divi- 
 
 sion of the fifth pair. It leaves the orbit through the supra- 
 orbital notch, and is at first covered by the orbicularis and occipito- 
 frontalis. But it presently divides into wide-spreading branches, 
 
 G 
 
82 TEMPORAL REGION. 
 
 which supply the skin of the forehead and scalp. ^The supra- 
 orbital artery is a branch of the ophthalmic. 
 
 The infra-orbital nerve is the terminal branch of the superior 
 maxillary or second division of the fifth nerve. It emerges with 
 its artery from the infra-orbital foramen, covered by the levator 
 labii superioris. The nerve immediately divides into several 
 branches, palpebral, nasal, and labial ; the palpebral, ascending 
 beneath the orbicularis, supply the lower eyelid, and communicate 
 with the facial : the nasal pass inwards to supply the nose and 
 join the nasal branch of the first division of the fifth ; the labial, 
 by far the most numerous, descend into the upper lip, and eventu- 
 ally terminate in lashes of filaments, which endow the papillae of 
 the lip with exquisite sensibility. 
 
 The infra-orbital artery is the terminal branch of the internal 
 maxillary ; it supplies the muscles and skin, and inosculates with 
 branches of the facial. 
 
 The mental nerve is a branch of the inferior maxillary or third 
 division of the fifth. It emerges from the mental foramen in the 
 lower jaw, in a direction upwards and backwards, beneath the 
 depressor labii inferioris. It soon divides into a number of 
 branches, some of which supply the skin of the chin, but the 
 greater number terminate in the papillae of the lower lip. 
 
 The mental artery is a branch of the inferior dental. It sup- 
 plies the gums and the chin, and inosculates with the sub-mental 
 and inferior coronary arteries. 
 
 MUSCLES OF MASTICATION.- TEMPORAL AND SPHENO-MAXILLARY 
 
 REGIONS. 
 
 In this dissection, the parts should be examined in the following 
 order : 
 
 1. Superficial arteries and nerves of the 5. Pterygoid muscles. 
 
 temple. 6. Internal maxillary artery and 
 
 2. Masseter muscle. branches. 
 
 3. Temporal aponeurosis. 7. Inferior maxillary nerve and 
 
 4. Temporal muscle. branches. 
 
TEMPORAL REGION. 83 
 
 Reflect the skin of the temple from below upwards. Under the 
 skin you come upon a layer of tough fibro-cellular tissue, con- 
 tinuous, above, with the aponeurosis of the scalp, below, with the 
 fascia covering the masseter and the parotid gland. In this tissue 
 are contained the superficial temporal vessels and nerves. 
 
 This is the smaller of the two terminal branches of 
 artery"* 1 the externa l carotid. Arising in the substance of the 
 parotid gland near the neck of the jaw, it passes over 
 the root of the zygoma close to the rneatus auditorius, ascends 
 for about an inch and a half upon the temporal fascia, and there 
 divides into an anterior and a posterior branch. Above the 
 zygoma it is superficial, being covered only by the attrahens 
 aurem muscle ; here it is accompanied by the temporo-auricular 
 branch of the inferior division of the fifth nerve. It gives off 
 the following branches : 
 
 a. Several small branches to the parotid. 
 
 6. The transversalis faciei (p. 77). 
 
 c. The anterior auricular branches ramify on the front of the 
 pinna of the ear, inosculating with the posterior auricular. 
 
 d. The middle temporal, a small vessel, pierces the temporal 
 fascia above the zygoma, and running in the substance of the tem- 
 poral muscle, anastomoses with the temporal branches of the 
 internal maxillary. 
 
 Of the two branches into which the temporal divides, the ante- 
 rior runs tortuously towards the external angle of the frontal bone, 
 distant from it about an inch. Its ramifications, extend over the 
 forehead, supplying the orbicularis and frontalis m., and inosculate 
 with the supra-orbital and frontal arteries. The posterior runs 
 towards the back of the head, and inosculates freely with the occi- 
 pital and posterior auricular. The anterior branch is usually 
 selected for arteriotomy, the posterior being covered by a strong 
 and unyielding fascia. 
 
 Temporo- Th * s nerve supplies the temples and side of the head 
 
 auricular with common sensation. It arises from the third divi- 
 sion of the fifth pair by two roots (between which the 
 * middle meningeal artery' runs). From its origin it proceeds 
 
 oS 
 
84 TEMPORAL REGION. 
 
 outwards between the neck of the jaw and the internal lateral 
 ligament, over the root of the zjgoma, where it joins the temporal 
 artery, and divides like it into an anterior and a posterior branch. 
 Its ramifications correspond with those of the artery. 
 
 Near the condyle of the jaw the temporo-auricular nerve sends 
 branches to the upper division of the facial nerve, endowing it 
 with common sensibility. It here distributes branches to the 
 parotid gland, meatus auditorius, and the articulation of the jaw. 
 Above the zygoma it gives filaments (auricular) to the outer 
 surface of the pinna of the ear. 
 
 Lastly, in the subcutaneous tissue of the temple, we find the 
 temporal branches of the facial nerve, which supply the frontalis, 
 the attrahens aurem, the orbicularis oculi, tensor tarsi, and corru- 
 gator supercilii. 
 
 This muscle arises from the lower edge of the zygoma, 
 Masseter an( j j g i, nser ted into the outer side of the ramus and 
 
 muscle. 
 
 coronoid process of the jaw. The masseter is composed 
 of superficial and deep fibres which cross like the letter X. The 
 superficial fibres, constituting the principal part of the muscle, 
 arise from the anterior two-thirds of the zygoma by a strong 
 tendon which occupies the front border of the muscle, and sends 
 aponeurotic partitions into its substance. These fibres pass down- 
 wards and backwards, this direction giving them greater advantage, 
 and are inserted into the angle and part of the ramus of the jaw. 
 The deep fibres (which are concealed by the parotid gland) arise 
 from the posterior part of the zygoma, incline forwards, and are 
 inserted into the upper half of the ramus and the coronoid process. 
 Besides these, a few fibres, arising from the inner surface of the 
 zygoma, are inserted into the coronoid process and the tendon of 
 the temporal muscle. Its action is to masticate the food: it 
 closes the jaw with great force. 
 
 The following objects lie upon the masseter : 1. Glandula socia 
 parotidis, and parotid duct ; 2. Transversalis faciei artery ; 3. 
 Facial artery and vein ; 4. Branches of the facial nerve. 
 
 Eeflect the masseter from its origin. Observe the direction of 
 the superficial and deep fibres, and the tendinous partitions which 
 
SPHENO-MAXILLARY REGION. 85 
 
 augment the power of the muscle by increasing its extent of origin. 
 The masseteric nerve and artery enter the under surface of the 
 muscle through the sigmoid notch of the jaw; the artery comes 
 from the internal maxillary, the nerve from the motor division of 
 the inferior maxillary. 
 
 This strong shining membrane covers the temporal 
 Temporal muscle ; its chief use being to give additional origin to 
 
 aponeurosis. 
 
 it. It is attached above to the temporal ridge, and 
 increasing in thickness as it descends, divides near the zygoma 
 into two layers, which are attached to the outer and inner surfaces 
 of the zygomatic arch. These layers are separated by fat, in 
 which is found a filament from the orbital branch of the supe- 
 rior maxillary nerve. The density of this aponeurosis explains 
 why abscesses in the temporal fossa rarely point outwards; the 
 matter makes its way, beneath the zygoma, into the mouth. 
 
 Keflect the aponeurosis, and notice that it is separated from the 
 temporal muscle, near the zygoma, by fat. The absorption of this 
 fat, and the wasting of the muscle, occasion the sinking of the 
 temple in emaciation and old age. 
 
 This muscle arises from the temporal fossa and the 
 muscle 1 temporal aponeurosis. It is inserted by a strong tendon 
 
 into the inner surface, the apex, and anterior border of 
 the coronoid process. 
 
 The fibres of this muscle converging from their wide origin, pass 
 under the zygomatic arch, and terminate upon their tendon, the 
 outer surface of which is partially concealed by the insertion of 
 those fibres which come from the temporal aponeurosis : remove 
 them, and see how admirably this tendon radiates into the muscle 
 like the ribs of a fan. Thus the force of the muscle is collected 
 into one focus. 
 
 Eemove the zygomatic arch, to expose the coronoid 
 nmxUlary process of the jaw, the insertion of the temporal muscle, 
 or pterygo- and the loose fat which surrounds it. Next, saw through 
 
 tne coronoid process in a direction downwards and 
 
 forwards, so as to include the insertion of the muscle, 
 and reflect it upwards without injuring the subjacent vessels and 
 nerves. 
 
86 
 
 SPHENO-MAXILLARY KEGION. 
 
 To gain a good view of the muscles, nerves, and vessels of the 
 pterygo-maxillary region, a portion of the ascending ramus of the 
 jaw must be removed with a Hey's saw, as shown in the diagram 
 below. 
 
 In this region we have to examine the two pterygoid muscles, 
 the trunk and branches of the internal maxillary artery and 
 nerve, and the internal lateral ligament of the lower jaw. 
 
 This muscle arises by two heads, one from the outer 
 surface of the external pterygoid plate (a few fibres 
 taking origin from the outer side of the tuberosity of 
 the palate bone) ; the other from the great wing of the sphenoid. 
 It is inserted into the neck of the jaw, and slightly into the 
 border of the inter-articular fibre-cartilage of the joint of the jaw. 
 
 Anterior temporal n. and a. 
 
 Fig. 15. 
 
 External pterygoid m. 
 
 Posterior temporal n. and a. 
 | Masseteric n. and a. 
 
 I 
 
 Infra-orbital a. 
 Spheno-maxillary 
 fossa . . . 
 
 Superior dental a. 
 Buccal a. . . . 
 
 Parotid duct . . 
 
 Buccal n. . . . 
 
 Pterygo-maxillary 
 
 ligament. . . . 
 
 i Inter-articular 
 
 fibre-cartilage. 
 Temporal-artery 
 and nerve. 
 
 Middle meningeaU. 
 
 Inferior dental a. 
 -Inferior dental n. 
 Gustatory n. 
 Mylo-hyoid n. 
 Internal pterygoid m. 
 
 PTERYGOID MUSCLES AND INTERNAL MAXILLARY ARTERY. 
 
 The object of the insertion of some of its fibres into the inter- 
 articular cartilage is, that the cartilage may follow the condyle in 
 
SPHENO-MAXILLARY REGION. 87 
 
 all its movements. When the jaw is dislocated, it is chiefly by 
 the action of this muscle, which pulls the condyle into the zygo- 
 matic fossa ; the inter-articular cartilage being dislocated with the 
 condyle. 
 
 This muscle arises from the inner surface of the ex- 
 pterygoid. ternal pterygoid plate, and tuberosity of the palate 
 bone. It is inserted into the inner side of the angle of 
 the jaw. 
 
 Notice particularly the direction of the fibres of the pterygoid 
 muscles. The fibres of the external run horizontally outwards and 
 backwards from their origin ; the fibres of the internal run 
 downwards, backwards, and outwards from their origin. In 
 structure, these muscles are similar to the masseter ; that is, they 
 are intersected by tendinous septa for the purpose of giving origin 
 to muscular fibres. 
 
 The action of the pterygoid muscles is to produce the lateral 
 movements of the jaw essential to the mastication of the food. 
 Consequently they are enormously developed in all ruminants, 
 and comparatively feebly in carnivorous animals. 
 
 Cut through the neck of the jaw, and disarticulate the condyle 
 with its fibre-cartilage from the glenoid cavity, and turn it 
 forwards with the external pterygoid, so that the condyle can be 
 replaced if desirable. A little dissection will bring into view the 
 internal lateral ligament, and the internal maxillary artery. 
 Internal ^is * s one ^ *k e terminal branches into which the 
 
 maxillary external carotid divides opposite the neck of the jaw. 
 It passes horizontally forwards between the neck of the 
 jaw and the internal lateral ligament, then runs tortuously, in 
 some cases above, in others beneath the external pterygoid, 
 enters the spheno-maxillary fossa between the two heads of the 
 external pterygoid, and terminates by dividing into several 
 branches. 
 
 The course of this artery is divided into three stages. In the 
 first, the artery lies between the neck of the jaw and the internal 
 lateral ligament; in the second, it lies either over or under 
 the external pterygoid ; in the third, it lies in the spheno-maxillary 
 fossa. 
 
88 
 
 INTERNAL MAXILLARY ARTERY. 
 
 BRANCHES OF THE INTEKNAL MAXILLARY ARTERY IN THE THREE 
 STAGES OF ITS COURSE. 
 
 BRANCHES IN THE FIRST 
 
 STAGE. 
 
 Tympanic. 
 Meningea media. 
 Meningea parva. 
 Inferior dental. 
 
 BRANCHES IN THE SECOND BRANCHES IN THE THIRD 
 
 STAGE. STAGE. 
 
 Six to the muscles of masti- 
 cation, namely: 
 Masseteric. 
 Anterior and posterior 
 
 temporal. 
 External and internal 
 
 pterygoid. 
 Buccal. 
 
 Superior dental. 
 
 Infra-orbital. 
 
 Descending palatine. 
 
 Vidian. 
 
 Nasal or spheno-palatine. 
 
 Pterygo-palatine. 
 
 GL The tympanic ascends behind the jaw, and passes through 
 the glenoid fissure to the tympanum. It supplies the membrana 
 tympani, and anastomoses with the stylo-mastoid and Vidian 
 arteries. 
 
 Fig. 16. 
 
 Third stage. Second stage. First stage. 
 
 PLAN OF INTERNAL MAXILLARY ARTERY. 
 
 6. The middle meningeal artery ascends between the two roots 
 of the temporo-auricular nerve through the foramen spinosum into 
 the cranium, where it ramifies between the dura mater and the 
 bones. 
 
INTERNAL MAXILLARY ARTERY. 
 
 c. The meningea parva ascends through the foramen ovale into 
 the skull, and supplies chiefly the ganglion of the fifth pair. It 
 often comes from the meningea media. 
 
 d. The inferior dental artery descends behind the neck of the 
 jaw to the dental foramen, which it enters with the dental nerve. 
 It then proceeds through a canal in the diploe to the symphysis, 
 where it minutely inosculates with its fellow. In this canal, which 
 runs beneath the roots of all the teeth, the artery gives branches 
 which ascend through the little apertures in the fangs, and ramify 
 upon the pulp in their interior. Opposite the foramen mentale 
 arises the mental branch already described (p. 82). Before enter- 
 ing the jaw the dental artery furnishes a small branch mylo-' 
 hyoid which accompanies the nerve proceeding to the mylo-hyoid^. 
 muscle. 
 
 e. The masseteric branch passes through the sigmoid notch of 
 the jaw to the unde surface of the masseter, with the masseteric 
 nerve, and inosculates with the facial artery. 
 
 f. The anterior and posterior temporal arteries ascend to supply 
 the temporal muscle, ramifying close to the bone, one near the 
 front, the other near the posterior border of the muscle. 
 
 g. The pterygoid branches supply the internal and external 
 pterygoid muscles. 
 
 h. The buccal branch runs forwards with the buccal nerve to 
 the buccinator. 
 
 i. The superior-dental branch runs along the back part of the 
 superior maxillary bone, and sends small arteries through the 
 foramina in the bone to the pulps of the molar and bicuspid teeth. 
 It also supplies the gums. 
 
 j. The infra-orbital branch passes through the spheno-maxillary 
 fissure, then runs forwards along the infra-orbital canal with the 
 superior maxillary nerve, and emerges upon the face at the infra- 
 orbital foramen. In the infra-orbital canal the artery sends 
 branches downwards through little canals in the bone to the in- 
 cisor and canine teeth. 
 
 k. The descending palatine, a branch of considerable size, runs 
 down the posterior palatine canal with the palatine nerve (a 
 
90 INFERIOR MAXILLARY NERVE. 
 
 branch from Meckel's ganglion), and then along thereof of the 
 hard palate, towards the anterior palatine canal, in which, much 
 diminished in size, it inosculates on the septum nasi with a branch 
 of the spheno-palatine artery. It supplies the gums, the glands, 
 and mucous membrane of this part, and furnishes branches to the 
 soft palate. 
 
 L The Vidian, an insignificant branch, runs backwards through 
 the Vidian canal with the Vidian nerve, and is lost upon the 
 Eustachian tube and the pharynx. 
 
 m. The nasal or spheno-palatine branch enters the nose, 
 through the spheno-palatine foramen in company with the nasal 
 nerve from Meckel's (spheno-palatine) ganglion, and ramifies upon 
 the spongy bones and the septum narium. 
 
 n. The pterygo-palatine is a small but constant branch which 
 runs backwards through the pterygo-palatine canal, and ramifies 
 upon the upper part of the pharynx and the Eustachian tube. 
 
 The internal maxillary vein is formed by the veins correspond- 
 ing to the branches of the artery. It joins the temporal in the 
 substance of the parotid gland, and forms the external jugular. 
 
 This great nerve is the largest of the three divisions 
 maxilkry of the fifth cerebral nerve. It differs from the other 
 nerve and two divisions, i. e. the ophthalmic and the superior 
 maxillary, in that it contains motor as well as sensitive 
 filaments; the motor being furnished by the small non-ganglionic 
 root of the fifth nerve. Thus much of its physiology it is neces- 
 sary to know, in order to understand its extensive distribution ; 
 for the sensitive portion supplies the parts to which it is distri- 
 buted with common sensation only, whilst the motor portion sup- 
 plies all the muscles concerned in mastication. 
 
 The nerve, then, composed of sensitive and motor filaments, 
 emerges from the skull through the foramen ovale as a thick 
 trunk, under the name of the inferior maxillary. It lies directly 
 external to the Eustachian tube, and is covered by the external 
 pterygoid muscle, which should be turned on one side to expose 
 it. Immediately after its exit from the skull, the nerve divides 
 into its several branches : some, destined for the muscles, contain 
 
INFERIOR MAXILLARY NERVE. 91 
 
 motor as well as sensitive filaments ; others are purely sensitive, 
 as follow : 
 
 BRANCHES OF THE INFERIOR MAXILLARY NERVE. 
 
 BRANCHES OF COMMON SENSATION.] 
 
 Temporo-auricular. 
 Inferior dental. 
 Bucca|. 
 Gustatory. 
 
 BRANCHES MOTOR. 
 
 To temporal muscle. 
 
 masseter. 
 
 external pterygoid. 
 
 internal pterygoid. 
 
 tensor palati. 
 
 mylo-hyoideus. 
 
 anterior belly of digastricus. 
 
 The branches to the temporal muscle, two in number, gass 
 outwards close to the great wing of the sphenoid bone, and ascend 
 with the temporal arteries to the muscle. 
 
 The branch to the masseter runs outwards above the external 
 pterygoid, through the sigmoid notch of the jaw. 
 
 The branch to the external pterygoid comes apparently from 
 the buccal nerve in its passage through this muscle. 
 
 The branch to the internal pterygoid and tensor palati muscles 
 is rather difficult to find. It proceeds from the inner side of 
 the main trunk, close to the otic ganglion, and descends between 
 the internal pterygoid and the tensor palati, supplying them both. 
 
 The buccal branch passes either above or between the fibres of 
 the external pterygoid to the buccinator, where it spreads out into 
 filaments, which supply the skin, mucous membrane, and glands 
 of the cheek with common sensation. The motor power of the 
 buccinator, remember, is derived from the facial nerve. That this 
 buccal branch is purely sensory is proved by the action of the 
 muscle still continuing when the motor division of the fifth nerve 
 is paralysed. The evidence is corroborated by a case in which this 
 buccal branch proceeded from the second division of the fifth 
 nerve ; no communication being discovered, after very careful dis- 
 section, between it and the motor root of the third division.* 
 
 * Turner ' On the variation of the buccal nerve. 5 Journal of Anat. and Phys. No. I. 
 . 1866. 
 
92 
 
 INFERIOR MAXILLARY NERVE. 
 
 The temporo-aiiricular branch arises by two roots which embrace 
 the middle meningeal artery before it enters the skull. The nerve 
 runs outwards behind the external pterygoid and the neck of the 
 jaw, ascends over the root of the zygoma with the temporal artery, 
 and divides, like it, into an anterior and a posterior branch : these 
 are distributed to the skin of the side of the head. Behind the 
 
 Fig. 17. 
 
 PLAN OF THE BRANCHES OF THE INFEBIOE MAXILLARY NERVE. 
 
 condyle it sends filaments to the meatus auditorius, to the skin on 
 the outer aspect of the ear and to the articulation of the jaw. It 
 distributes also gland filaments to the parotid, and one especially 
 to the upper division of the facial, which endows it with common 
 sensibility. 
 
 The inferior dental branch emerges beneath the external ptery- 
 goid, and descends between the ramus of the jaw and the internal 
 
INFERIOR MAXILLARY NERVE. 93 
 
 lateral ligament of the jaw to the dental foramen, which it enters 
 with the dental artery. It then runs in the canal in the diploe of 
 the jaw below the fangs of all the teeth. It furnishes filaments 
 which ascend through the canals in the fangs of the teeth to the 
 pulp in their interior. Opposite the foramen mentale the mental 
 branch is given off. Observe that the same nerve which supplies 
 the teeth supplies the gums ; hence the sympathy between them. 
 
 The mylo-hyoid branch, apparently arising from the dental, is 
 derived from the motor root of the fifth, and may, with careful 
 dissection, be traced to it. It leaves the dental nerve near the 
 foramen in the jaw, and runs in a groove on the inner side of the 
 ramus to the lower surface of the mylo-hyoid, which muscle, 
 together with the anterior portion of the digastricus, it supplies 
 (p. 36). 
 
 The gustatory branch descends first between the ramus of the 
 jaw and the internal pterygoid, then for a short distance between 
 the jaw and the superior constrictor of the pharynx. Here it lies 
 close to the mucous membrane of the mouth near the last molar 
 tooth of the lower jaw ; and division of it here has been recom- 
 mended to relieve pain in cancer of the tongue. The gusta- 
 tory n. then crosses obliquely the stylo-glossus, and running along 
 the hyo-glossus to the tongue, is distributed to the papillas of its 
 tip and sides. 
 
 Beneath the external pterygoid the gustatory nerve is joined at 
 an acute angle by the chorda tympani (a branch of the facial). 
 This branch emerges from the glenoid fissure, and meeting the 
 gustatory, runs along the lower border of that nerve to join the 
 submaxillary ganglion. It is eventually distributed to the lingual is 
 muscle. 
 
 This 'so-called' ligament proceeds from the spinous 
 lateral process of the sphenoid bone, and is attached to the 
 
 ligament j aw on the inner side of the foramen dentale. Between 
 16 Ja ^ this ligament and the neck of the jaw we find the in- 
 ternal maxillary artery and vein, the temporo-auricular nerve, the 
 middle meningeal artery, the dental nerve and artery, and a por- j 
 tion of the parotid gland. 
 
94 STYLOID MUSCLES. 
 
 At this stage of the dissection you will be able tp trace the 
 course and relations of the internal carotid artery. But before 
 doing this, examine the several objects which intervene between 
 the external and internal carotid. These are 1. The stylo-glossus, 
 2. The stylo-pharyngeus, 3. The glosso-pharyngeal nerve, 4. The 
 stylo-hyoid ligament. 
 
 This arises from the styloid process near the apex, 
 
 St y l0 " and the stylo-maxillary ligament, and is inserted along 
 
 the side of the tongue, external to the hyo-glossus. 
 
 Its action is to retract the tongue. Its nerve comes from the hypo- 
 
 This arises from the styloid process near the base, 
 stylo " pha " and is inserted into the posterior edge of the thyroid 
 cartilage. It descends along the side of the pharynx 
 between the superior and the middle constrictor. Curving round 
 lower border is seen the glosso-pharyngeal nerve. Its nerve 
 from the pharyngeal plexus. Its action is to raise the 
 /fcl larynx with the pharynx in deglutition. 
 
 Between the stylo-glossus and stylo-pharyngeus, and nearly 
 parallel with both, is the stylo-hyoid ligament. It extends from 
 the apex of the styloid process to the lesser cornu of the os- 
 hyoides. It is often more or less ossified, 
 
 The ascending palatine artery, a branch of the external maxil- 
 lary or facial (p. 38), runs up between the stylo-glossus and the 
 stylo-pharyngeus, and divides into branches which supply these 
 muscles, the palate, the side of the pharynx, and the tonsils. It 
 inosculates with the descending palatine, a branch of the internal 
 maxillary. 
 
 The glosso-pharyngeal nerve is observed curving for- 
 wards un der the lower border of the stylo-pharyngeus. 
 It is one of the divisions of the eighth pair. It arises 
 by four or five filaments from the medulla oblongata in the groove 
 between the olivary body and the restiform tract. It leaves the 
 skull through the anterior part of the foramen lacerum posterius in 
 front of the remaining divisions of the eighth pair, and descends 
 between the internal jugular vein and the internal carotid artery. 
 
PHARYNGEAL PLEXUS. INTERNAL CAROTID. 95 
 
 It then crosses in front of the artery and proceeds along the lower 
 border of the stylo-pharyngeus. It now curves forwards over 
 that muscle and the middle constrictor of the pharynx, and dis- 
 appears beneath the hyo-glossus, where it divides into its terminal 
 branches for the supply of the mucous membrane of the pharynx, 
 the back of the tongue and the tonsils. 
 
 According to the present state of our knowledge, the glosso- 
 pharyngeal is, at its origin, purely a sensitive nerve. But soon 
 after its exit from the skull it receives communications from the 
 facial, the pneumogastric and the sympathetic, so that it soon 
 becomes a compound nerve i.e. composed of both sensitive and 
 motor filaments. At the base of the skull it is provided with two 
 ganglia the jugular and the petrous (ganglion of Andersch). 
 The minute branches given off by these ganglia will be noticed 
 hereafter ; at present we are more concerned with what is called 
 the f pharyngeal plexus ' of nerves. 
 
 By the side of the middle constrictor of the pharynx, 
 Pharyngeal ^""find a n intricate interlacement of nerves, constituting 
 
 plexus. 
 
 the plexus which presides over deglutition. Its dissec- 
 tion requires much time and care, and a pharynx prepared exclu- 
 sively for the purpose. The nerves which compose it are derived 
 from the glosso-pharyngeal, the pneumogastric, the sjpinal acces- 
 sory, and the sympathetic. Consequently it possesses nerves of 
 three different kinds ganglionic, sensitive, and motor. Its minute 
 ramifications supply the pharynx, the back of the tongue, and 
 tonsils. 
 
 Course and The internal carotid artery, proceeding from the divi- 
 relatkms s ion of the common carotid, opposite the upper border 
 nal carotid f the thyroid cartilage, ascends to the base of the skull, 
 artery. fay $IQ side of the pharynx close to the transverse pro- 
 
 cesses of the three upper cervical vertebrae. It enters the skull 
 through the carotid canal in the temporal bone, runs very tortu- 
 ously by the side of the body of the sphenoid, and terminates in 
 branches which supply the orbit and the brain. In the first part 
 of its course, it is situated immediately outside the external 
 carotid, near the inner border of the sterno-mastoid.^ But it 
 
96 PNEUMOGASTRIC NEEVE. 
 
 soon gets beneath the external carotid, and lies deeply seated by 
 the side of the pharynx. In its course it is crossed successively 
 by the hypoglpssal nerve, the occipital artery, the digastricus and 
 stylo-hyoid muscles ; higher, it is crossed obliquely, by the styloid 
 process, by the stylo-glossus and pharyngeus muscles, by the 
 glosso-pharyngeal nerve, and the stylo-hyoid ligament, all of 
 which last intervene between it and the external carotid. 
 
 The internal jugular vein runs along the outer side of the 
 artery. Behind the artery are the pneumogastric nerve and the 
 superior cervical ganglion of the sympathetic. The rectus capitis 
 anticus major separates it from the cervical vertebra?. But after 
 all, the most important relation of the artery in a surgical point 
 of view is, that it ascends close by the side of the pharynx and 
 tonsils. In opening an abscess, therefore, near the tonsils, or at 
 the back of the pharynx, be careful to introduce the knife with 
 its point inwards towards the mesial line : observe this caution 
 the more, because, in some subjects, the internal carotid makes a 
 curve, or even a complete curl upon itself, in its ascent near the 
 pharynx. In such cases the least deviation of the instrument in 
 an outward direction would injure the vessel. 
 
 Ascendin ^ n * s arterv general^ arises from the angle of the 
 pharyngeal common carotid, or from the commencement of the 
 external carotid ; it ascends between the internal 
 carotid artery and the side of the pharynx, towards the base of 
 the skull. It gives off branches which supply the pharynx, the 
 tonsils, the Eustachian tube, and the muscles in front of the spine. 
 A very constant branch runs down with the levator palati, above 
 the superior constrictor of the pharynx, and supplies the soft 
 palate. It also sends small meningeal branches to supply the 
 dura mater ; one of which ascends through the foramen lacerum 
 medium, and the other through the foramen jugulare with the 
 internal jugular vein. 
 
 Pneumo- ^ ne P neumo g a stric nerve is one of the three divisions 
 
 gastric of the eighth pair of cerebral nerves. It arises from 
 
 the medulla oblongata by a series of roots along the 
 
 groove between the olivary body and the restiform tract. It 
 
PNEUMOGASTRIC NEKVE. 97 
 
 passes out of the skull with the nervus accessorius through the 
 foramen jugulare. 
 
 Leaving the skull at the foramen jugulare, the nerve descends 
 in front of the cervical vertebrae, lying successively upon the 
 rectus capitis anticus major and the longus colli. In the upper 
 part 'of the neck it is situated behind the internal carotid artery ; 
 in the lower, between and behind the common carotid and the 
 internal jugular vein. It enters the chest, on the right side 
 crossing in front of the subclavian artery nearly at a right angle ; 
 on the left running nearly parallel with it. 
 
 In their course through the chest, the pneumogastric nerves 
 have not similar relations. The right nerve lies beneath the 
 subclavian vein, and then descending by the side of the trachea, 
 is continued behind the right bronchus to the posterior part of 
 the oesophagus. The left nerve passes behind the left brachio- 
 cephalic vein, then^os^s'TnTrontoT'tte arch of the aorta, and 
 behind the left bronchus to the anterior part of the oesophagus. 
 Both nerves subdivide on this tube into a plexus ; the right nerve 
 forming the posterior, and the left, the anterior wsophageal plexus. 
 Each plexus again collects its fibres together : thus two main 
 nerves are formed which pass with the oesophagus through the 
 diaphragm : of these the right is distributed over the posterior, 
 the left over the anterior surface of the stomach. 
 
 In their long course from the medulla oblongata to the abdo- 
 men, the pneumogastric nerves supply branches to most important 
 organs ; namely, to the pharynx, the larynx, the heart, the lungs, 
 the oesophagus, and the stomach. 
 
 Within the foramen jugulare, a small ganglion (Arnold's 
 ganglion) is formed upon the pneumogastric nerve, which is then 
 joined by a branch of considerable size from the nervus acces- 
 sorius. Arnold's ganglion will be described hereafter. But soon 
 after leaving the skull, the pneumogastric nerve swells out, and 
 forms a second ganglion (inferior ganglion) of a reddish-grey 
 colour. This ganglion occupies about an inch of the nerve, but 
 does not involve the whole of its fibres; the branch from the 
 spinal accessory not being included. It is united to the hypo- 
 
98 PNEUMOGASTRIC NERVE. 
 
 glossal nerve, from which it receives filaments. 1 1^ also receives 
 filaments from the first and second spinal nerves, and from the 
 superior cervical ganglion of the sympathetic. 
 
 Thus, the pneumogastric, at its origin probably a nerve of 
 sensation only, becomes, in consequence of the reinforcements 
 from these various branches, a compound nerve, and in all re- 
 spects analogous to a spinal nerve. Its branches are 
 
 1. The auricular (Arnold), which will be described hereafter. 
 
 2. The gha^yngeal, which arises from the inferior ganglion, and 
 descends either in front of or behind the internal carotid to join 
 the pharyngeal plexus (p. 95). 
 
 3. The superior laryngeal, also derived from the inferior 
 ganglion, descends behind the internal carotid to the interval 
 between the os-hyoides and the thyroid cartilage, where it enters 
 the larjmx through the thyro-hyoid membrane, and is distributed 
 to the mucous membrane of the larynx. The superior laryngeal 
 nerve gives off the ' external laryngeal," 1 which descends beneath 
 the depressors of the os-hyoides to supply the crico-thyroid 
 muscle. 
 
 4. The cardiac, two in number, which descend behind the 
 sheath of the carotid to the cardiac plexus. The upper branch is 
 small, and proceeds from the inferior ganglion ; the lower comes 
 from the main trunk in its course down the neck. On their 
 passage to the heart, the right cardiac nerves rim chiefly behind 
 the arch of the aorta to the deep cardiac plexus ; the left, chiefly 
 in front of it, to the superficial cardiac plexus. 
 
 5. The inferior laryngeal or recurrent branch of the pneumo- 
 gaslric turns on the right side under the subclavian artery (p. 53), 
 and runs up to the larynx, between the trachea and the bodies of 
 the cervical vertebra : on the left side, it turns under the arch 
 of the aorta, and ascends to the larynx between the trachea 
 and the oesophagus. On both sides it enters the larynx beneath 
 the lower border of the inferior constrictor, and supplies all the 
 intrinsic muscles of the larynx, except the crico-thyroid. The 
 remaining branches of the pneumogastric, to the lungs, the 
 oesophagus and stomach, will be examined in the dissection of 
 the chest. 
 
SYMPATHETIC NERVE IN THE NECK. 99 
 
 Now examine the cervical ganglia of the sympathetic 
 C s J stem of nerves. Speaking in general terms of this 
 system, it may be said that it consists of a series of 
 ganglia arranged on either side of the spine, from the first cervical 
 to the last sacral vertebra. The successive ganglia of the same 
 side are connected by intermediate nerves, so as to form a con- 
 tinuous cord on each side of the spine : this constitutes what is 
 called the trunk of the sympathetic system, and is connected with 
 all the spinal nerves. Its upper or cephalic extremity penetrates 
 into the cranium through the carotid canal, surrounds the internal 
 carotid artery, communicates with the third, fourth, fifth, and 
 sixth cranial nerves, and joins its fellow of the, opposite side upon 
 the anterior communicating artery.* Its sacral extremity joins 
 its fellow by means of a little ' ganglion irupar,' situated in the 
 mesial line, upon the last sacral vertebra. 
 
 The sympathetic system presides over the functions of those 
 organs which are withdrawn from our control. Thus it regulates 
 the circulation of the blood, respiration, digestion, and secretion. 
 Cervical gan- ^ R ^ oe cervical portion of the sympathetic are three 
 glia of sym- ganglia, named from their position, superior, middle, 
 
 pathetic. and inferior> 
 
 The superior cervical ganglion, the largest of the three, ^is 
 situated near the base of the skull, opposite the bodies of the 
 second and third cervical vertebrae, and lies behind the internal 
 carotid artery, upon the rectus capitis anticus major. It is of a 
 reddish-grey colour like other ganglia, of an elongated oval shape, 
 varying in length from one to two inches. To facilitate the 
 description of its several branches we divide them into 1st, those 
 which are presumed to connect it with other nerves ; and 2ndly, 
 those which originate from it. 
 
 It is then connected by branches as follow : 
 
 a. With each of the four upper spinal nerves. 
 
 6. With the hypoglossal, pneumogastric, and glosso-pharyngeal 
 nerves. 
 
 W "It '' O 
 
 * Here is situated the ' so-called ' ganglion of Kibes. (- 
 
 H2 
 
100 SYMPATHETIC NERVE IN THE NECK. 
 
 c. With the third, fourth, fifth, and sixth cerebral nerves (in the 
 cavernous sinus). 
 
 d. With the several ganglia of the sympathetic system about 
 the head and neck ; namely, the ophthalmic, spheno-palatine, otic, 
 and submaxillary. 
 
 The branches which it distributes are 
 
 e. Nerves to the heart. One or more descend behind the sheath 
 of the carotid, and entering the chest, join the cardiac plexuses, 
 superficial and deep. 
 
 /. Nerves to the pharynx. These join the pharyngeal plexus on 
 the middle constrictor of the pharynx. 
 
 g. Nerves to the blood-vessels. These nerves, named on account 
 of their delicacy * nervi molles,' ramify around the external carotid 
 artery and its branches. 
 
 The middle cervical ganglion is something less than a barley- 
 corn in size. It is situated behind the carotid sheath, about the 
 fifth or sixth cervical vertebra, near the inferior thyroid artery. 
 It receives branches from the fifth and sixth spinal nerves, and 
 gives off 
 
 a. Branches to the thyroid body. These accompany the inferior 
 thyroid artery. 
 
 b. Branch to the heart. This usually descends in front of the 
 subclavian artery into the chest, and joins the deep cardiac 
 plexus. 
 
 In cases where the middle cervical ganglion is absent, the pre- 
 ceding nerves are supplied by the sympathetic cord connecting the 
 superior and inferior ganglia. 
 
 The inferior cervical ganglion is of considerable size, and 
 is situated in the interval between the transverse process of 
 the seventh cervical vertebra and the first rib, immediately 
 behind the vertebral artery. It receives branches from the 
 seventh and eighth spinal nerves, and others which, descending 
 from the fourth, fifth, and sixth, through the foramina in the 
 transverse processes of the vertebrae, form a plexus around the 
 vertebral artery. 
 
 The branches which it gives off are 
 
DISSECTION OF THE CHEST. 101 
 
 a. Inferior cardiac nerve. This communicates with the re- 
 current laryngeal, and joins the cardiac plexus beneath the arch of 
 the aorta. 
 
 b. Nerves to the blood-vessels. These ramify around the verte- 
 bra] and subclavian arteries. 
 
 DISSECTION OF THE CHEST. 
 
 Before the several organs contained in the chest are examined, 
 we ought to have some knowledge of its frame-work. The true 
 ribs with their cartilages describe a series of arcs, increasing in 
 length from above downwards, and form with the spine behind, 
 and the sternum in front, a barrel of a conical shape, broader in 
 the lateral than in the antero-posterior direction. The lower 
 aperture or base of the cavity is closed in the recent state by the 
 diaphragm, which forms a muscular partition between the chest 
 and the abdomen. This partition is arched, so that it constitutes 
 a vaulted floor for the chest, and by its capability of alternately 
 falling and rising can increase or diminish the capaciousness of the 
 chest. The spaces between the ribs are filled by the intercostal 
 muscles. In each intercostal space there are two layers of these 
 muscles, arranged like the letter X. The fibres of the outer layer 
 run obliquely from above downwards, and forwards ; those of the 
 inner layer in the reverse direction. 
 
 The upper aperture of the chest gives passage to the trachea, 
 the oesophagus, the great vessels of the head, neck, and upper 
 extremities, the superior intercostal, and internal mammary arteries, 
 the inferior thyroid veins, the sterno-hyoid, sterno-thyroid, and 
 longus colli muscles, the pneumogastric, the left recurrent laryn- 
 geal, the phrenic, and the sympathetic nerves ; also to the first 
 dorsal passing up to join the brachial plexus, the thoracic duct, and, 
 lastly, to the apices of the lungs ; the interspaces between these 
 parts being occupied by a dense fibro-cellular tissue. 
 
 Such, in outline, is the frame-work of the cavity, closed on all 
 sides, which contains the heart and lungs. Observe that its walls 
 are made up of different structures, bone, cartilage, and muscle, 
 
102 DISSECTION OF THE CHEST. 
 
 admirably disposed to fulfil two important conditions. By their 
 solidity and elasticity they protect the important organs contained 
 in them ; by their alternate dilatation and contraction they act as 
 mechanical powers of respiration. For they can increase the cavity 
 of the chest in three directions : in height, by the descent of the 
 diaphragm ; in width, by the turning outwards of the ribs ; and in 
 depth, by the elevation of the sternum. 
 
 The chest of the female differs from that of the male in the 
 following points: Its general capacity is less; .the sternum is 
 shorter ; the upper opening is larger in proportion to the lower ; 
 the upper ribs are more movable, and therefore permit a greater 
 enlargement of the chest at its upper part, in adaptation to the 
 condition of the abdomen during pregnancy. 
 
 In the dissection of the chest let us take the parts in the 
 following order : 
 
 1. Triangular is sterni, with the internal mammary artery. 
 
 2. Anterior mediastintun. 
 
 3. Right and left brachio-cephalic veins and superior vena cava 
 
 4. Course and relations of the arch of the aorta. 
 
 5. The three great branches of the arch. 
 
 6. Course of the phrenic nerves. 
 
 7. Position and relations of the heart. 
 
 8. Pericardium. 
 
 9. Pleura. 
 
 10. Position and form of the lungs. 
 
 11. Posterior mediastinum and its contents ; namely, the aorta, the thoracic duct, 
 
 the vena azygos, the oesophagus, and pneumogastric nerves. 
 
 12. Sympathetic nerve. 
 
 13. Intercostal muscles, vessels, and nerves. 
 
 14. Cardiac plexus of nerves. 
 
 An opening must be made into the chest, by carefully removing 
 the upper four-fifths of the sternum, and the cartilages of all the 
 true ribs.* In doing this, care must be taken not to wound the 
 pleura, which is closely connected with the cartilages. On one 
 
 * Those -who are more proficient in dissection should not remove the whole of the 
 sternum, but leave, say a quarter of an inch of its upper part with the first rib attached 
 to it. This little portion serves as a valuable landmark, although it obstructs, to a 
 certain extent, the view of the subjacent vessels. 
 
DISSECTION OF THE CHEST. 103 
 
 side the internal mammary artery should be removed ; on the other, 
 left. 
 
 On the under surface of the sternum and cartilages of 
 Triangularis the ribs is a muscle, named the ' triangularis sterni.' 
 It arises from the ensiform cartilage and the lower part 
 of the sternum, and is inserted by digitations into the carti- 
 lages of the true ribs from the sixth to the second: its fibres 
 ascend outwards to their insertion ; its action is to depress the 
 costal cartilages. Thus, on emergency, it acts in expiration. Its 7 
 nerve comes from the intercostal nerves, its arteries from the 
 internal mammary. 
 
 Internal This artery springs from the subclavian in the first 
 
 mammary part of its course. On entering the chest it is crossed 
 artery. ^y ^ & ph ren j c nerve. It then descends perpendicularly, 
 
 about half an inch from the sternum, between the cartilages of 
 the ribs and the triangularis sterni : it then enters the wall of the 
 abdomen behind the rectus abdominis, and finally inosculates with 
 the epigastric (a branch of the external iliac). Its branches are 
 as follow : 
 
 a. Arteria comes nervi phrenici. A very slender artery, which 
 accompanies the phrenic nerve to the diaphragm, and anastomoses 
 with the phrenic branches of the abdominal aorta. 
 
 b. Mediastinal and tJtymic. These branches supply the cellular 
 tissue of the anterior mediastinum, the pericardium, and the tri- 
 angularis sterni. The thymic are only visible in childhood, and 
 disappear with the thymus gland. 
 
 c. Anterior intercostal. One, and often two, for each inter- 
 costal space are distributed to the five or six upper intercostal 
 spaces. They lie at first between the pleura and the internal 
 intercostal muscle, and subsequently between the two intercostals. 
 They inosculate with the intercostal arteries from the aorta, 
 
 d. Perforating arteries, which pass through the same number 
 of intercostal spaces as the preceding branches, and supply the 
 pectoral muscle and skin of the chest. In the female they are of 
 large size, for the supply of the mammary gland. 
 
 e. The intercosto-phrenic branch runs outwards behind the 
 
 
104 
 
 DISSECTION OF THE CHEST. 
 
 cartilages of the false ribs, and terminates near the last intercostal 
 space. It supplies small arteries to the diaphragm, to the sixth, 
 seventh, and sometimes the eighth intercostal spaces. 
 
 Two venaB comites surround the artery, and unite into a single 
 trunk in the upper part of the chest, to terminate in the brachio- 
 cephalic vein of its own side. 
 
 There are several absorbent glands in the neighbourhood of the 
 internal mammary artery. They receive the absorbents from the 
 inner portion of the mammary gland, from the diaphragm, and 
 the upper part of the abdominal wall. In disease of the inner 
 portion of the mamma, these glands may enlarge without any 
 enlargement of those in the axilla. 
 .,, ,. .. The ' mediastina ' are the spaces which the two 
 
 Mediastma, 
 
 anterior and pleural sacs leave between them in the antero-posterior 
 posterior. pl ane o f the chest. There is an anterior and a pos- 
 terior mediastinum. To put these spaces in the simplest light, 
 let us imagine the heart and lungs to be removed from the chest, 
 and the two pleural sacs to be left in it by themselves. The two 
 sacs, if inflated, would then appear like two bladders, in contact 
 only in the middle, as shown by the dotted outlines in the an- 
 nexed scheme (fig. 18). The interval marked a, behind the 
 
 sternum, would represent the an- 
 terior mediastinum : the interval 
 6, the posterior mediastinum. 
 But now let us introduce the heart 
 and lungs again, between the 
 two pleural sacs : these must give 
 way to make room for them, so 
 that the two sacs are not in contact 
 anywhere in the middle line of 
 the chest. 
 
 Therefore, with the heart and 
 lungs interposed, the pleural sacs 
 appear as shown in the diagram, fig. 19, which represents a trans- 
 verse section through the chest. Here you see that the heart and 
 the lungs become invested by the pleural sacs ; or, to speak more 
 
DISSECTION OF THE CHEST. 
 
 105 
 
 technically, the sacs are reflected over the heart and the lungs, on 
 each side respectively. But the anterior and posterior mediastina 
 remain unaltered. 
 
 Looking at the chest in front, the anterior mediastinum appears 
 as shown in the cut (p. 117). It is not precisely longitudinal in 
 its direction, but inclines slightly towards the left, owing to the 
 position of the heart. Its area varies : thus it is extremely narrow 
 in the middle where the edges of the lungs nearly meet ; but it is 
 wider above and below, where the lungs diverge. 
 
 What parts are contained in the anterior mediastinum ? The 
 remains of the thymus gland, the origins of the sterno-hyoid, sterno- 
 thyroid, and triangularis sterni muscles, the left brachio-cephalic 
 vein (which crosses behind the first bone of the sternum), and a 
 few absorbent glands. 
 
 Fig. 19. 
 
 Internal mam- 
 mary a. . , 
 
 Phrenic n. . . 
 
 Internal mam- 
 mary a. 
 
 Phrenic n . 
 
 (Esophagus with 
 
 n. vagi. 
 Aorta. 
 
 .Thoracic duct. 
 Vena azygoa. 
 
 DIAGRAM OF THE REFLECTIONS OF THE PLETJRAL SACS IN DOTTED LINES. 
 
 The posterior mediastinum (fig. 19) contains the cesophagus, 
 the two pneumogastric nerves, the aorta, the thoracic duct, and the 
 vena azygos. 
 
 A middle mediastinum is described by some anatomists. It 
 is the largest of the mediastina, and contains the heart with its 
 
106 BEACHIOCEPHALIC VEINS. 
 
 large vessels, the phrenic nerves, and the bifurcation of the 
 trachea. 
 
 Before we can display the brachio-cephalic veins, we must 
 remove a layer of the deep cervical fascia, which descends over 
 them from the neck, and is lost upon the pericardium. Their 
 coats are closely connected to this fascia ; and its chief use appears 
 to be to keep the veins always open for the free return of blood to 
 the heart. 
 
 The right and left brachio-cephalic (innominate) 
 
 Brachio- & . i \ , . . 
 
 cephalic veins are formed, near the sternal end of the clavicle, 
 veins. ^ ^ e con fl ue nce of the internal jugular and subclavian. 
 
 They differ in their course and relations, and must, therefore, be 
 described separately. 
 
 The left brachio-cephalic vein passes obliquely behind the first 
 bone of the sternum towards the right side, to join the vena cava 
 superior. It is about two inches and a half in length, and its 
 direction inclines a little downwards. It crosses over the trachea 
 and the origins of the three primary branches of the arch of the 
 aorta. We are reminded of this fact in some cases of aneurism of 
 these vessels ; for what happens ? The vein becomes compressed 
 between the aneurism and the sternum ; hence the swelling and 
 venous congestion of the parts from which it returns the blood ; 
 namely, of the left arm and left side of the neck. The upper 
 border of the vein lies not far from the upper border of the 
 sternum ; in some instances it lies even higher, and I have seen it 
 crossing in front of the trachea a full inch above the sternum. 
 This occasional deviation should be borne in mind in the perform- 
 ance of tracheotomy. 
 
 The right brachio-cephalic vein descends nearly vertically to 
 join the superior vena cava, opposite the first intercostal space. 
 It is about one and a half inch in length, and is situated about one 
 inch from the mesial line of the sternum. On its left side, but on 
 a posterior plane, runs the arteria innominata; on its right side is 
 the pleura. Between the vein and the pleura is the phrenic nerve. 
 The brachio-cephalic veins are not provided with valves. The 
 veins which empty themselves into the right and left brachio- 
 cephalic are as follow : 
 
VENA CAVA SUPERIOR. 
 
 107 
 
 The EIGHT B. C. Vein receives : 
 
 The vertebral. 
 
 The deep cervical. 
 
 The internal mammary. 
 
 The inferior thyroid (sometimes). 
 
 The LEFT B. C. Vein receives 
 The vertebral. 
 The deep cervical. 
 The internal mammary. 
 The inferior thyroid. 
 The superior intercostal. 
 The pericardiac. 
 
 This is the great channel through which the impure 
 blocd from the head, upper extremities, and chest, 
 returns into the right auricle. It is formed by the 
 confluence of the right and left brachio-cephalic veins, which 
 unite at nearly a right angle opposite the first intercostal space 
 on the right border of the sternum ; that is, about the level of the 
 highest point of the arch of the aorta (p. 53). The vena cava descends 
 
 Fig. 20. 
 
 Middle thyroid. 
 
 Internal jugular. 
 External jugular. 
 Vertebral. 
 
 Supra scapular. 
 Posterior scapular. 
 Subclavian. 
 
 Internal mammary . 
 Pericardiac. 
 
 Superior inter- 
 costal. 
 
 Superior intercostal . 
 Internal mammary . . 
 
 Vena azygos .... 
 
 SUPERIOR VENA CAVA AND ITS TRIBUTARIES. 
 
 vertically, with a slight inclination backwards, to the upper part 
 of the right auricle. It is from two and a half to three inches 
 long. The lower half of it is covered by the pericardium ; you 
 must, therefore, open this sac to see that the serous layer of the 
 pericardium is reflected over the front and sides of the vein. In 
 respect to its relations, notice that the vein lies in front of the 
 right bronchus and the right pulmonary vessels; and that it is 
 
108 ARCH OF THE AORTA. 
 
 overlapped by the ascending aorta, which lies to its left side and 
 parallel with it. In the upper half of its course, that is, above 
 the pericardium, it is covered on its right side by the pleura ; on 
 this side, in contact with it, descends the phrenic nerve. 
 
 Before it is covered by the pericardium, the vena cava receives 
 the right vena azygos, which comes in arching over the right 
 bronchus. 
 
 The aorta is the great trunk from which all the 
 arteries of the body carrying pure blood are derived. 
 the arch of ft arises from the upper and back part of the left ven- 
 tricle of the heart. Its origin is situated behind the 
 pulmonary artery and on the left side of the sternum, about the 
 level of the third intercostal space. It ascends forwards and to 
 the right as high as the first intercostal space on the right side ; 
 it then curves backwards towards the left side of the body of the 
 second dorsal vertebra, and turning downwards over the left side 
 of the third, completes the arch. The direction of the arch, 
 therefore, is from the sternum to the spine, and rather oblique 
 from right to left. 
 
 The arch of the aorta presents partial dilatations in certain 
 situations. One of these, called the ' sinus ' or bulge of the aorta, 
 is observed on the right side of the arch, about the junction of 
 the ascending with the transverse portion : it is little marked in 
 the infant, but increases with age. Three other dilatations (the 
 sinuses of Valsalva), one corresponding to each of the valves at 
 the commencement of the aorta, will be examined hereafter. 
 
 For convenience of description, the arch of the aorta is divided 
 into an ascending, a transverse, and a descending portion. 
 
 Ascending portion, To see this portion of the aorta, the 
 pericardium must be opened. You then observe that this part of 
 the artery is covered all round by the serous layer of the peri- 
 cardium, except where it is in contact with the pulmonary artery. 
 It is about two inches in length, and ascends with a slight curve 
 to the upper border of the second costal cartilage of the right side. 
 Its commencement is covered by the pulmonary artery, and over- 
 lapped by the appendix of the right auricle. On its right side, 
 
ARCH OF THE AORTA. 109 
 
 but on a posterior plane, descends the superior vena cava ; on its 
 left is the division of the pulmonary artery ; behind it, are part of 
 the auricle, the right pulmonary artery, and the right bronchus. 
 This part of the aorta gives off the right and left coronary arteries 
 for the supply of the heart. 
 
 Transverse portion. This portion of the aorta arches from the 
 front to the back of the thorax, and extends from the upper 
 border of the second right costal cartilage to the left side of the 
 second dorsal vertebra. In front it is covered by the left pleura, 
 and is crossed by the left phrenic and pneumogastric nerves. 
 Near its summit runs the left brachio-cephalic vein; within its 
 concavity are the left bronchus, the bifurcation of the pulmonary 
 artery, the left recurrent laryngeal nerve, and the remains of the 
 ductus arteriosus. The artery rests upon the trachea a little 
 above its bifurcation, the oesophagus, thoracic duct, and the left 
 recurrent laryngeal nerve. From the" transverse part of the arch 
 arise the arteria innominata, the left carotid, and subclavian 
 arteries. 
 
 Descending portion. This part of the arch lies upon the left 
 side of the body of the third dorsal vertebra. On its right side 
 are the oesophagus and thoracic duct ; on its left is the pleura. 
 
 What parts are contained within the arch of the aorta ? The 
 left bronchus, the right pulmonary artery, the left recurrent 
 nerve, the remains of the ductus arteriosus, and the deep cardiac 
 plexus. 
 
 These relations vary according to the size of the 
 the^arch of heart, the obliquity of the ribs, and the general de- 
 the aorta to velopment of the chest. In a well-formed adult the 
 
 the sternum. , . ., . P , 
 
 ascending aorta is, at the most prominent part of its 
 bulge, about half of an inch behind the first bone of the sternum. 
 The highest part of the arch is about one inch below the upper 
 edge of the sternum.* 
 
 * The relations of the arch of the aorta to the sternum vary even in adults, more 
 especially if there be any hypertrophy of the heart. As an instance among many, I 
 may mention that of a young female who died of phthisis. The position of the aortic 
 valves was opposite the middle of the sternum, on a level with the middle of the 
 
HO LEFT CAROTID ARTERY. 
 
 From the upper part of the arch arise three great arteries for 
 the head, neck, and upper limbs ; namely, the brachio-cephalic or 
 innominate artery, the left carotid, and the left subclavian. 
 
 This arises from the commencement of the trans- 
 
 B itf o~ r C in- verse P art of the arch> Jt ascends obliquely towards 
 nominate the right, and after a course of about one inch and a 
 half, divides behind the right sterno-clavicular joint 
 into two arteries of nearly equal size the right carotid, and the 
 right subclavian. 
 
 What are the relations of the innominate artery? It ascends 
 obliquely in front of the trachea ; the right brachio-cephalic vein 
 descends on its right side ; the left brachio-cephalic and inferior 
 thyroid veins cross in front of it : parallel and close to the artery 
 are the slender cardiac nerves.* 
 
 With the anatomy of the parts before you, it is easy to under- 
 stand that an aneurism of the innominate artery might be distin- 
 guished from an aneurism of the aorta J. By a pulsation in the 
 neck between the sterno-mastoid muscles, i.e. in the fossa above 
 the sternum ; 2. By occasional dyspnoea owing to pressure on the 
 trachea; 3. By venous congestion in the left arm; 4. By the 
 aneurismal thrill being confined to the right arm. 
 
 This artery arises from the arch of the aorta close to 
 "* ^ ne ai> teria innominata. It ascends obliquely behind 
 
 the first bone of the sternum to the neck. In the first 
 part of its course it lies upon the trachea, but it soon passes to the 
 left side of the trachea, and then lies for a short distance upon the 
 oesophagus and thoracic duct. It is crossed by the left brachio- 
 cephalic vein ; on its outer side are the left subclavian artery and 
 
 second costal articulation. The highest part of the arch was on a level with the 
 tipper border of the sternum; the arteria innominata was situated entirely in front of 
 the trachea ; and the left brachio-cephalic vein crossed the trachea so much above the 
 sternum that it would have been directly exposed to injury in tracheotomy. 
 
 * In some cases the innominate artery ascends for a short distance above the 
 clavicle before it divides, lying close to the right of the trachea. We have already 
 alluded to the fact that it occasionally gives off a middle thyroid artery (p. 31), which 
 ascends in front of the trachea to the thyroid body, and is therefore directly in the 
 way in tracheotomy, 
 
PHRENIC NERVES. Ill 
 
 pneumogastric nerve, and on the inner side is the arteria in- 
 norninata. In the rest of its course it resembles the right 
 carotid (p. 27). 
 
 This is the third branch of the arch. It ascends out of the 
 chest to the inner border of the first rib. and then 
 
 Left sub- 
 
 clavian curves outwards behind the scalenus anticus. In the 
 artery. ^.^ ^^ Q f -^ course jfc j s deeply seated, and is 
 
 covered on its left side by the pleura. Close to its right side 
 are the trachea and oesophagus; between the artery and the 
 oesophagus we find the thoracic duct. Like the other primary 
 branches of the arch, it is crossed by the left brachio-cephalic vein. 
 It is covered in front by the left lung, and it rests upon the 
 longus colli. The upper part of its course, where the vessel 
 passes in front of the apex of the lung, has been described with 
 the anatomy of the neck (p. 54). 
 
 The phrenic nerve comes from the third, fourth, and 
 phrenic nerves fifth cervical nerves. It descends over the scalenus 
 through the anticus, and enters the chest between the subclavian 
 
 chest. . 
 
 vein and artery. It then runs in front of the root 
 of the lung between the pleura and the pericardium to the dia- 
 phragm (fig. 21), to the under surface of which it is distributed. 
 
 In what respects do the phrenic nerves differ from each other in 
 their course ? The right phrenic runs along the outer side of the 
 brachio-cephalic vein and superior vena cava; the left crosses 
 in front of the transverse part of the arch of the aorta ; besides 
 which, the left is rather longer than the right, because it has to go 
 round the apex of the heart.* 
 
 Before the phrenic nerve divides into branches to supply the 
 diaphragm, it sends off minute filaments to the pleura and the 
 pericardium. 
 
 Having studied these anatomical details, consider for a moment 
 what kind of symptoms are likely to be produced by an aneurism 
 of the arch of the aorta, or any of the primary branches. A glance 
 at the important parts in the neighbourhood will answer the 
 
 * In the upper part of the chest the phrenic is sometimes joined by a branch from 
 the brachial plexus, less frequently by a branch from the descendens noni. 
 
112 
 
 PHRENIC NERVES. 
 
 question. The effects will vary according to the part of the artery 
 which is the seat of the aneurism, and, according to the volume 
 the form, and the position of the tumour. One can understand 
 
 Fig. 21. 
 
 3rd cervical n. 
 
 Phrenic n. 
 
 Line of reflec- 
 tion of peri- 
 cardium. 
 
 Cervicalis ascendens a. 
 Scalenus anticus. 
 Inferior thyroid a. 
 Superficialis colli a. 
 Phrenic n. 
 Posterior scapular a. 
 
 Supra scapular a. 
 Subclavian a. 
 Superior intercostal a. 
 Internal mammary a. 
 Pneumogastric n. 
 
 Phrenic n. 
 
 Appendix of left auricle. 
 
 that compression of the vena cava superior, or either of the brachio- 
 cephalic veins, would occasion swelling and congestion of the parts 
 from which it returns the blood ; that compression of the trachea 
 or one of the bronchi might occasion dyspnoea, and thus simulate 
 
POSITION OF THE HEART. 113 
 
 disease of the larynx;* that compression of the oesophagus would 
 give rise to symptoms of stricture. Nor must we forget the imme- 
 diate vicinity of the thoracic duct and the recurrent nerve,f and 
 the effects which would be produced by their compression. Can 
 one, then, be surprised that a disease which may give rise to so 
 many different symptoms should be a fertile source of fallacy in 
 diagnosis ? 
 
 You can easily see how aneurisms of the aorta prove fatal, by 
 bursting into the contiguous tubes or cavities ; for instance, into 
 the trachea, the oesophagus, the pleura, or the pericardium. You 
 will see, too, why an aneurism of the first part of the arch is so 
 much more dangerous than elsewhere. The reason is, that in this 
 part of its course the aorta is covered only by a thin layer of serous 
 membrane : now if an aneurism take place here, the coats of the 
 vessel soon become distended, give way, and allow the blood to 
 escape into the pericardium ; an occurrence which is speedily fatal, 
 because, the pericardium being filled with blood, prevents the 
 heart from acting. 
 
 Position and ^ e ^ ear ^ * s situated obliquejy in the chest, between 
 form of the the lungs. Its base, i.e. the part by which it is at- 
 heart. tached, and from which its great vessels proceed, is 
 
 directed upwards towards the right shoulder ; its apex points 
 downwards and to the left, between the fifth and sixth costal car- 
 tilages. It is supported by the tendinous centre of the diaphragm. 
 It is maintained in its position by a membranous bag termed the 
 ' pericardium,' which is lined by a serous membrane to facilitate 
 its movements. The pericardium must first claim our attention. 
 
 The pericardium is the membranous bag which en- 
 closes the heart and the large vessels at its base. It 
 is broadest below, where it is attached to the tendinous centre of 
 the diaphragm ; above it is prolonged over the great vessels of 
 the heart, and is connected with the deep cervical fascia. On each 
 
 * In the Museum of Guy's Hospital there is a preparation, No. 1487, in which 
 laryngotomy was performed under the circumstances described in the text. 
 
 f See Med. G-az., Dec. 22nd, 1843. A case in which loss of voice was produced by 
 the pressure of an aneurismal tumour upon the left recurrent nerfl. 
 
 I 
 
114 
 
 POSITION OF THE HEART. 
 
 side it is covered by the pleura; the phrenic nerve running down 
 between them. In front of it, is the anterior mediastinum ; behind 
 
 Fig. 22. 
 
 RELATIVE POSITION OF THE HEART AND ITS VALVES WITH REGARD TO THE WALLS OF 
 
 THE CHEST. 
 
 The valves are denoted by curved lines. The aortic valves are opposite the third in- 
 tercostal space on the left side, close to the sternum. The pulmonary valves are 
 just above the aortic, opposite the junction of the third rib with the sternum. The 
 mitral valves are opposite the third intercostal space, about one inch to the left of 
 the sternum. The tricuspid valves lie behind the middle of the sternum, about the 
 level of the fourth rib. Aortic murmurs, as shown by the arrow, are propagated 
 up the aorta : mitral murmurs, as shown by the arrow, are propagated towards the 
 apex of the heart. 
 
 it, the posterior. Of all the objects in the posterior mediastinum, 
 that which is nearest to the pericardium is the oesophagus. It is 
 
PERICARDIUM. 115 
 
 worth remembering that the oesophagus is in close contact with 
 the back of the pericardium for nearly two inches; this fact 
 accounts for what one sometimes observes in cases of pericarditis 
 where there is much effusion ; I mean pain and difficulty in swal- 
 lowing. 
 
 The pericardium is what is called a 'fibro serous ' membrane. 
 Its fibrous layer, which constitutes its chief strength, is external. 
 This layer is attached below to the central tendon of the diaphragm. 
 Above, it forms eight sheaths for the vessels at the base of the 
 heart ; namely, one for the vena cava superior, four for the pul- 
 monary veins, two for the pulmonary arteries, and one for the 
 aorta. The serous layer forms a shut sac. It lines the fibrous 
 layer, and is reflected over the great vessels and the heart. To see 
 where the serous layer is reflected over the vessels, distend the 
 pericardium with air. Thus you will find that this layer is reflected 
 over the aorta as high as the origin of the arteria innominata. It 
 is reflected over the vena cava superior, after the entrance of the 
 vena azygos.* 
 
 In the healthy state the capacity of the pericardium pretty 
 nearly corresponds to the size of the heart when distended to its 
 utmost. The healthy pericardium, with the heart in situ, may be 
 made to hold in the adult about ten ounces of fluid. The peri- 
 cardium is not extensible. When an aneurism bursts into it, death 
 
 * Those who choose to follow the reflections of the serous layer of the pericardium, 
 will find that it covers the great vessels to an extent greater than is generally imagined; 
 though in truth the extent is not precisely similar in all bodies. The aorta and pul- 
 monary artery are wrapped in a complete sheath, two inches in length, so that these 
 vessels are covered all round by the serous layer, except where they are in contact. 
 Indeed you can pass your finger behind them both, thrcragh a foramen bounded in 
 front by the two great vessels themselves, behind, by the upper part of the auricles, 
 and above by the right pulmonary artery. Again, the back of the aorta, where it 
 lies on tbe auricles, is covered by the serous pericardium. The superior cava is covered 
 all round, except behind where it crosses the right pulmonary artery. What little 
 there is of the inferior cava within the pericardium is also covered all round. The 
 left pulmonary veins are covered nearly all round ; the right less so. Behind the 
 auricles, chiefly the left, the serous layer extends upwards in the form of a pouch, 
 rising above their upper border, so as to be loosely connected to the left bronchus. 
 
 i 2 
 
116 PK^ECORDIAL KEGION. 
 
 is caused not by loss of blood, but by compression of the heart in 
 consequence of the inextensibility of the pericardium. 
 
 The pericardium derives its blood from the internal mammary, 
 bronchial, and cesophageal arteries. 
 
 Cut open the pericardium, and observe that the heart is conical 
 in form, and convex everywhere except upon its lower surface, 
 which is flat, and rests upon the tendinous centre of the diaphragm. 
 When the pericardium is thus laid open, the following objects are 
 exposed: viz. 1. Part of the right ventricle; 2. Part of the left 
 ventricle; 3. Part of the right auricle with its appendix over- 
 lapping the root of the aorta ; 4. The appendix of the left auricle 
 overlapping the root of the pulmonary artery ; 5. The aorta ; 6. 
 The pulmonary artery ; 7. The vena cava superior ; 8. The right 
 and left coronary arteries. 
 
 The heart then is placed behind the lower half of the sternum, 
 occupies more of the left than the right half of the chest, and rests 
 upon the central tendon of the diaphragm, which is nearly on a 
 plane with the lowest part of the fifth rib. At each contraction 
 the apex of the heart may be felt beating between the cartilages 
 of the fifth and sixth ribs, about two inches below the nipple, and 
 one inch on its sternal side. Its base extends as high as the upper 
 border of the third costal cartilage, and about half an inch to the 
 right of the sternum. 
 
 The ( prcecordial region* is the outline of the heart 
 traced upon the front wall of the chest. We ought to 
 be able to define this region with something like pre- 
 cision. We should know how much of it is covered and separated 
 from the wall of the chest by intervening lung (fig. 23). This 
 then is the rule : Let the middle of the fifth costal cartilage be 
 the centre of a circle two inches in diameter : this circle will define 
 well enough, for all practical purposes, that part of the prascordial 
 region which is naturally less resonant to percussion ; here the 
 heart is uncovered except by pericardium and loose cellular tissue, 
 and is very near the wall of the chest. In the rest of the prse- 
 cordial region the heart is covered and separated from the chest 
 by intervening lung. 
 
THE LUNGS. 117 
 
 Where should we put the stethoscope when we listen to the 
 valves of the heart ? For practical purposes it is enough to 
 remember that the mouth of an ordinary-sized stethoscope will 
 cover a portion of them all, if it be placed a little to the left of 
 the mesial line of the sternum opposite the third intercostal space 
 (fig. 23). They are all covered by a thin portion of lung : there- 
 fore we ask a patient to stop breathing while we listen to his heart. 
 
 Fig. 23. 
 
 FORM OF THE LUNGS, AND THE EXTENT TO WHICH THEY OVERLAP THE HEART AND 
 
 ITS VALVES. 
 
 The position of the heart alters a little with the position of the 
 body. Of this any one may convince himself by leaning alternately 
 forwards and backwards, by lying on this side and on that, placing 
 at the same time the hand upon the prsecordial region. He will 
 find that he can, in a slight degree, alter the place and the extent 
 
] 18 PLEURA. 
 
 of the impulse of the heart. Inspiration and expiration also alter 
 the position of the heart. In inspiration the heart descends with 
 the tendinous centre of the diaphragm about half an inch. 
 
 As the lungs are continually gliding to and fro, within 
 the chest, they are provided with a serous membrane 
 to facilitate their motion. This membrane is termed the pleura. 
 There is one for each lung. Each pleura forms a completely 
 closed sac, and is disposed like all other serous sacs ; that is, one 
 part of the sac lines the containing cavity, the other is reflected 
 over the contained organ. Its several parts are named after the 
 surface to which they adhere : that which lines the ribs is called 
 ' pleura costalis ; ' that which forms the mediastinum, ' pleura 
 mediastinalis ; ' that which covers the lung, ( pleura pulmonalis.' 
 Unlike the peritoneum, the pleura forms no folds except a small 
 one called ( ligamentum latum pulmonisj which extends from 
 the root of the lung to the diaphragm. 
 
 If asked to describe the reflections of the pleural sac (fig. 19, 
 p.105), I should say, that it lines the ribs and part of the sternum ; 
 from the sternum it is reflected backwards over the pericardium ; 
 from thence it passes over the front of the root of the lung, and so 
 on over the entire lung to the back part of its root, whence it is 
 reflected over the sides of the vertebrae, and thus reaches the ribs 
 again. 
 
 The spaces called ( anterior ' and c posterior ' mediastina, formed 
 by the pleura, have been already described, p. 104. 
 
 In health the internal surface of the pleura is smooth, polished, 
 and lubricated by moisture sufficient to facilitate the sliding of 
 the lung. When this surface is thickened and roughened by 
 inflammation, the moving lung produces a ' friction ' sound. 
 When the pleural sac is distended by serum, it constitutes hydro- 
 thorax ; when by pus, ' empyema ; ' and when by air, ' pneumo- 
 thorax.' 
 
 Introduce your hand into the pleural sac, and ascertain that the 
 reflection of the pleura on to the diaphragm corresponds with an 
 imaginary line commencing at the lower part of the sternum, and 
 sloping along the cartilages of the successive ribs down to the 
 
THE LUNGS. 119 
 
 lower border of the last rib. Suppose a musket ball to lodge in 
 the pleural sac, it would fall upon the dome of the diaphragm, 
 and roll down to the lowest part of the pleural cavity. The place, 
 therefore, to extract it would be in the back, at the eleventh 
 intercostal space. This operation has been done during life with 
 success. 
 
 Position and ^ke l un g s are situated in the chest, one on each side 
 form of the of the heart. Each fits accurately into the cavity which 
 contains it. Each, therefore, is conical in form; the 
 base rests on the diaphragm ; the apex projects in the neck a little 
 more than an inch above the sternal end of the clavicle. Its outer 
 surface is adapted to the ribs ; its inner surface is excavated to 
 make room for the heart. But the best way to see the shape of 
 the lungs is to inject the trachea with wax, which is tantamount to 
 taking a cast of each thoracic cavity. In such a preparation, 
 besides the general convexities and concavities alluded to, you 
 would find in the right lung a little indentation for the right 
 brachio-cephalic vein, in the left an indentation for the arch of the 
 aorta and the left subclavian artery. 
 
 Each lung is divided into an upper and a lower lobe by a deep 
 fissure, which commences behind about three inches from the 
 apex, and proceeds obliquely downwards to the front a little lower 
 than the fifth costal cartilage. Speaking broadly, the whole of the 
 anterior portion of the lung is formed by the upper lobe ; the whole 
 of the posterior portion by the lower lobe. It should be noticed, 
 however, that the upper lobe of the right lung is divided by a 
 second fissure which slices off a triangular portion called the 
 ' middle lobe.' 
 
 The dimensions of the right lung are greater than those of the 
 left in all directions except the vertical ; the reason of this excep- 
 tion is the greater elevation of the diaphragm on the right side 
 by the liver. On an average, the right lung is to the left, in point 
 of size, as 11 to 10. 
 
 To understand rightly the shape and play of the lungs in in- 
 spiration and expiration, take an opportunity of making the follow- 
 ing experiment : Cut away the intercostal muscles and the pleura, 
 
120 THE LUNGS. 
 
 without wounding the lungs, and then distend the lungs by blowing 
 into the trachea with bellows. Thus, you will ascertain how far 
 the front edge of the lung overlaps the pericardium ; how low the 
 lung descends between the ribs and the diaphragm on the side and 
 at the back of the chest. You will see the great gap in the left 
 lung for the point of the heart. By making the lung expand and 
 contract, you will observe how it slides along the pleural lining of 
 the chest. This sliding takes place in health in silence. But 
 when the naturally polished surface of the pleura becomes rough- 
 ened by inflammatory deposit, a sound of greater or less distinctness 
 (friction sound) may be heard. 
 
 The practical result of this investigation should be to enable us 
 to trace upon a living chest the outline of the lungs, that we may 
 know what parts are naturally resonant on percussion. 
 
 Commencing, then, from above (fig. 23, p. 117), we find that the 
 apex of the lung rises into the neck a little more than an inch 
 above the sternal end of the clavicle. This part of the lung 
 mounts up behind the subclavian artery and the anterior scalene 
 muscle, and deserves especial attention, because it is, more than 
 any other, the seat of tubercular disease. From the sternal end 
 of the clavicles the lungs converge towards the mesial line, where 
 their edges almost meet opposite the junction of the second rib. 
 There is little or no lung behind the first bone of the sternum. 
 
 From the level of the second costal cartilage to the level of the 
 fourth, the inner margins of each lung run parallel and almost 
 close behind the middle of the sternum; consequently they over- 
 lap the great vessels at the root of the heart. 
 
 Below the level of the fourth costal cartilage the margins of the 
 lungs diverge from each other, but not in an equal degree. The 
 left presents the notch for the heart, and curves nearly in the 
 course of the fourth costal cartilage ; at the lower part of its curve 
 it projects more or less over the apex of the heart. The right 
 descends almost perpendicularly behind the sternum as low as the 
 attachment of the ensiform cartilage, and then, turning outwards, 
 corresponds with the direction of the sixth costal cartilage. Hy- 
 pertrophy of the heart, or effusion into the pericardium, will not 
 
CONTENTS OF POSTERIOR MEDIASTINUM. 121 
 
 only raise above the ordinary level the point where the lungs 
 diverge, but also increase their divergence ; hence the greater 
 dulness on percussion. 
 
 The posterior mediastinum (p. 105) is formed by the 
 
 Posterior a _* * M. L '** * a 
 
 mediasti- reflection of the pleura! sac on each side, from the 
 
 content^ ^ root of tlie ^ im ^ to ^ e sicles of ^e Bodies of the dorsal 
 vertebrae. It is bounded in front by the pericardium. 
 To obtain a view of it, draw out the right lung, and fasten it to 
 the left side. This mediastinum contains the aorta ; in front of 
 the aorta, the oesophagus, with the pneumogastric nerves ; on the 
 right of the aorta is the vena azygos ; between this vein and the 
 aorta is the thoracic duct ; inferiorly are the splanchnic nerves 
 and some lymphatic glands. To expose these last, we have to 
 remove the pleura, and a layer of firm fascia which lines the 
 chest outside it. 
 
 We have already traced the arch of the aorta to the 
 lower border of the body of the third dorsal vertebra. 
 From this point, the aorta descends on the left side of 
 the spine, gradually approaching towards the middle line. Oppo- 
 site the last dorsal vertebra it passes between the crura of the 
 diaphragm and enters the abdomen. Its left side is covered by 
 pleura ; on its right run the vena azygos and thoracic duct ; in 
 front of it are, the root of the left lung, the pericardium, and 
 nearer to the mesial line is the oesophagus. Its branches will be 
 described presently. 
 
 This vein commences in the abdomen by small 
 
 Thoracic 
 aorta. 
 
 azygos. | 3ranc | ies f rom one O f th e lumbar veins, and generally 
 communicates with the renal, or the vena cava itself. This, indeed, 
 is the main point about the origin of the vena azygos, that it 
 communicates directly or indirectly with the vena cava inferior. 
 It enters the chest through the aortic opening of the diaphragm, 
 and ascends on the right side of the aorta through the posterior 
 mediastinum, in front of the bodies of the lower dorsal vertebra? 
 and over the right intercostal arteries. When the vein reaches the 
 level of the third dorsal vertebra, it arches over the right bronchus, 
 and terminates in the superior vena cava, just before this vessel is 
 
122 
 
 THORACIC DUCT. 
 
 Fig. 24. 
 
 covered by pericardium. In its course it receives all the right 
 intercostal veins, the spinal veins, the oesophageal and commonly 
 the right bronchial vein. Opposite the sixth dorsal vertebra 
 
 it is joined by the left vena 
 azygos. 
 
 The left vena azygos, 'vena 
 azygos minor,' runs up the left 
 side of the spine. This vein 
 commences in the abdomen by 
 small branches communicating 
 with the inferior vena cava, and 
 ascends on the left side of the 
 aorta, through the aortic opening 
 in the diaphragm. On a level 
 with the sixth or seventh dorsal 
 vertebra, it passes beneath the 
 aorta and joins the azygos major. 
 Before passing beneath the aorta 
 it usually communicates with the 
 left superior intercostal vein. It 
 receives five or six of the lower 
 intercostal veins of the left side. 
 None of these veins are provided 
 with valves. The purpose of the 
 azygos vein is to be supplemental 
 to the inferior vena cava. 
 
 The thoracic duct 
 Thoracic (% . ^ ig & c ^ 
 
 about eighteen inches 
 long, through which the contents 
 of the lacteal vessels from the 
 DIAGRAM TO SHOW THE COURSE OF THE intestines and the absorbents from 
 
 VENA AZYGOS AND THE THORACIC DUCT. ,11 v i j 
 
 the lower limbs are conveyed 
 
 into the blood. These vessels converge to a general receptacle, 
 termed ' receptaculum chyli,' situated in front of the body of 
 the second lumbar vertebra. From this receptacle, the duct passes 
 
(ESOPHAGUS. 123 
 
 through the aortic opening of the diaphragm into the chest, and 
 runs up the posterior mediastinum along the right side of the 
 aorta. Near the third dorsal vertebra, it passes under the oeso- 
 phagus, and ascends on the left side of this tube, between it and 
 the left subclavian artery, as high as the seventh cervical vertebra, 
 where it describes a curve with the convexity upwards, and opens 
 in front of the scalenus anticus into the back part of the confluence 
 of the left internal jugular and subclavian veins. The orifice of 
 the duct is guarded by two valves which permit fluid to pass 
 from the duct into the vein, but not vice versa. Valves, disposed 
 like those in the venous system, are placed at short intervals 
 along the duct, so that its contents can only pass upwards. The 
 duct is not much larger than a crow-quill ; its walls are thin and 
 transparent.* The calibre of the duct varies in size in different 
 parts of its course ; it is large at the commencement, diminishes 
 in the middle, and again enlarges towards the termination. 
 
 The ( oesophagus ' is that part of the alimentary canal 
 .sop agus. W j 1 j c | 1 convevs th e food from the pharynx to the stomach. 
 It commences about the fifth cervical vertebra, nearly opposite the 
 cricoid cartilage ; runs down first to the right side of the transverse 
 portion of the arch of the aorta, then through the posterior media- 
 stinum in front of the descending aorta, and passes -through a 
 special opening in the diaphragm to the stomach. It is from nine 
 to ten inches long. Its course is not exactly vertical : in the neck, 
 it lies to the left of the trachea; in the chest, i.e. about the 
 fourth dorsal vertebra, it inclines towards the right side, to make 
 way for the aorta ; but it again inclines to the left before it perforates 
 the diaphragm. 
 
 The oesophagus, in the first part of its course, rests upon the 
 longus colli muscle, then upon the third, fourth, and fifth inter- 
 
 * It is right to state that the thoracic duct varies in size in different individuals. 
 I have seen it of all sizes intermediate between a crow-quill and a goose-quill. It 
 may divide in its course into two branches, which subsequently reunite ; instead of 
 one, there may be several terminal orifices. Instances have been observed in which 
 the duct has terminated on the right instead of the left side (Fleischman, Leichen- 
 ceffnungen, 1815). It has been seen to terminate in the vena azygos (Miiller's Archives, 
 1834). 
 
124 PNEUMOGASTRIC IN THE CHEST. 
 
 costal vessels of the right side, and, lastly, lies in front, and slightly 
 to the left side of the aorta. In front of it is the left bronchus ; 
 and before it passes through the diaphragm it lies in close contact 
 with the pericardium for nearly two inches : this fact accounts for 
 the pain which is sometimes experienced in cases of pericarditis, 
 during the passage of food. The oesophagus is surrounded by a 
 nervous plexus, formed by the pneumogastric nerves, the left being 
 in front and the right behind it. 
 
 The oesophagus is supplied with blood by the inferior thyroid, 
 the cesophageal branches of the aorta, and the coronaria ventriculi. 
 It is supplied with nerves by the pneumogastric and the sympa- 
 thetic. The oesophagus is composed of three coats, an external or 
 muscular, a middle or cellular, and an internal or mucous. The 
 muscular coat consists of an outer longitudinal and an inner 
 circular layer of fibres. Both are of the non-striped variety. 
 The longitudinal layer is particularly strong, and arranged all 
 round the oesophagus so as to support the circular. The middle 
 coat is composed of cellular tissue, and connects very loosely the 
 muscular and mucous coats. The mucous membrane is of a pale 
 colour, and considerable thickness, and in the contracted state of 
 the oesophagus is arranged in longitudinal folds. It is lined by a 
 very thick layer of scaly epithelium. In the submucous tissue are 
 many small compound glands cesophageal glands especially 
 towards the lower end of the oesophagus. 
 
 Course and The right pneumogastric nerve enters the chest between 
 branches of ^he subclavian artery and vein, descends by the side of 
 
 the pneu- J J 
 
 mogastric the trachea, then behind the root of the right lung to 
 the posterior surface of the oesophagus, upon which it 
 divides into branches, which form a plexus (posterior cesophageal) 
 upon the tube. The plexus then reunites into a single trunk, 
 which passes into the abdomen through the cesophageal opening in 
 the diaphragm. The left pneumogastric descends into the chest 
 between the left subclavian and carotid arteries, and behind the 
 left brachio-cephalic vein. It then crosses in front of the arch 
 of the aorta, and passes behind the root of the left lung to the 
 anterior surface of the oesophagus, upon which it also forms a 
 
PNEUMOGASTRIC IN THE CHEST. 125 
 
 plexus (anterior oesophageal). The branches of the pneumogastric 
 nerve in the chest are as follow : 
 
 a. The inferior laryngeal or recurrent This nerve on the 
 right side turns under the subclavian and the common carotid 
 artery (p. 53) ; on the left, under the arch of the aorta, and 
 ascends to the larynx. It enters the larynx beneath the lower 
 border of the inferior constrictor of the pharynx. It supplies 
 with motor power all the muscles which act upon the rima 
 glottidis, except the crico-thyroid (supplied by the external la- 
 ryngeal branch of the superior laryngeal nerve). 
 
 b. Cardiac branches. These are very small, and join the cardiac 
 plexuses ; the right arise from the right recurrent laryngeal and 
 the right pneumogastric, close to the trachea ; the left come from 
 the left recurrent laryngeal nerve. 
 
 c. Pulmonary branches. These accompany the bronchial tubes. 
 The greater number run behind the root of the lung, forming the 
 posterior pulmonary plexus. A few, forming the anterior pul- 
 monary plexus, proceed over the front of the lung's root. Both 
 these plexuses are joined by filaments from the sympathetic system. 
 But the nerves of the lungs are very small, and cannot be traced 
 far into their substance.* 
 
 d. GEsophageal plexus. Below the root of the lung each 
 pneumogastric nerve is subdivided so as to form an interlacement 
 of nerves round the oesophagus (plexus guise). From this plexus 
 numerous filaments supply the coats of the tube ; but the majority 
 of them are collected into two nerves the continuation of the 
 left pneumogastric nerve lying in front of the oesophagus ; the con- 
 tinuation of the right lying behind it. Both nerves pass through 
 the diaphragm for the supply of the stomach. 
 
 Having examined the contents of the posterior mediastinum 
 from the right side, now do so from the left. The left lung is to 
 be turned out of its cavity and fastened by hooks towards the 
 right side. After removing the pleura, we see the descending 
 thoracic aorta, the pneumogastric nerve crossing the arch and 
 sending the recurrent branch through it ; also the first part of the 
 
 * Upon this subject, see the beautiful plates of Scarpa. 
 
126 
 
 SYMPATHETIC IN THE CHEST. 
 
 Fie. 25. 
 
 course of the left subclavian, covered externally by pleura. The 
 pneumogastric nerve must be traced behind the root of the left 
 luno- to the oesophagus, and the ossophageal plexus of this side 
 dissected. Lastly, notice the lesser vena azygos which crosses 
 under the aorta about the sixth or seventh dorsal vertebra to join 
 the vena azygos major. 
 
 This portion of the sympathetic system is generally 
 
 Thoracic por- J r ^ J 
 
 tion of the composed oi twelve ganglia covered by the pleura ; one 
 
 sympathetic. g an gii on being found over the head of each rib. Often 
 there are only ten ganglia, in consequence of one or two of them 
 
 fusing together. The first thoracic 
 ganglion is the largest. 
 
 Each ganglion is connected by two 
 branches with the corresponding spinal 
 nerve. The nerves proceeding from 
 the ganglia pass inwards to supply 
 the thoracic and part of the abdominal 
 viscera. The branches which proceed 
 from the upper six ganglia are small 
 and are distributed as follow (see the 
 diagram ) : 
 
 a. Minute nerves from the first and 
 second ganglia to the deep cardiac 
 plexus. 
 
 b. Minute nerves from the third 
 and fourth ganglia to the posterior 
 pulmonary plexus. 
 
 The branches arising from the six 
 lower ganglia unite to for in three nerves 
 the great splanchnic, the lesser, and 
 the smallest splanchnic nerves. 
 
 a. The great splanchnic nerve is 
 generally formed by branches from 
 the sixth to the tenth ganglia. They 
 descend obliquely along the sides of 
 
 , ,. ' , , . , , 
 
 ? bodies ot the dorsal vertebrae, ana 
 
 SOLAR PLEXUS I/ t 
 
 I/ A 
 
 DIAGRAM OF THE THORACIC PORTION 
 OF THE 
 
INTERCOSTAL VESSELS. 127 
 
 unite into a single nerve, which, passes through the corresponding 
 crus of the diaphragm, and joins the semilunar ganglion of the 
 abdomen, sending also branches to the renal plexus. 
 
 b. The lesser splanchnic nerve is commonly formed by branches 
 from the tenth and the eleventh ganglia. It passes through the 
 crus of the diaphragm to the renal plexus.*" 
 
 c. The smallest splanchnic nerve comes from the twelfth 
 ganglion, passes through the crus of the diaphragm, and terminates 
 in the renal plexus. (This is not seen in the diagram.) 
 
 The intercostal muscles occupy the intervals between 
 the ribs - Between eacn rib tnere are two layers of 
 muscles which cross like the letter X. The external 
 layer runs obliquely from behind, forwards, like the external 
 oblique muscle of the abdomen. The internal layer runs from 
 before backwards like the internal oblique. Observe that a few 
 fibres of the inner layer pass over one or even two ribs, and ter- 
 minate upon a rib lower down. 
 
 But neither of these layers extends all the way between the 
 sternum and the spine : the outer layer, beginning at the spine, 
 ceases at the cartilages of the ribs ; the inner, commencing at the 
 sternum, ceases at the angles of the ribs. 
 
 The intercostal muscles present a curious intermixture of tendi- 
 nous and fleshy fibres ; and they are covered inside and outside 
 the chest by a glistening fascia, to give greater protection to the 
 intercostal spaces. 
 
 The external intercostal muscles elevate the ribs, and are there- 
 fore muscles of inspiration. The internal intercostal muscles de- 
 press the ribs, and are therefore muscles of expiration. 
 
 There are twelve intercostal arteries on each side. 
 
 arteries^ 1 The two ll PP er are supplied by the intercostal branch 
 
 of the subclavian ; the remaining ten are furnished by 
 
 the aorta : and since this vessel lies rather on the left side of the 
 
 spine, the right intercostal arteries are longer than the left. The 
 
 * In a few instances we have traced a minute filament from one of the ganglia into 
 the body of a vertebra. According to a celebrated French anatomist (Cruvcilhier), 
 each vertebra receives one. 
 
128 INTERCOSTAL VESSELS. 
 
 upper intercostal arteries from the aorta ascend obliquely to reach 
 their intercostal spaces; the lower run more transversely. As 
 they pass outwards, they are covered by the pleura and the sympa- 
 thetic nerves ; the right, in addition, pass behind the oesophagus, 
 thoracic duct, and the vena azygos major. Having reached the 
 intercostal space, each artery divides into an anterior and a 
 posterior branch. The anterior branch in direction and size 
 appears to be the continuation of the common trunk. At first it 
 rims along the middle of the intercostal space, lying upon the 
 external intercostal muscle, and is separated from the cavity of 
 the chest by the pleura and intercostal fascia. Here, therefore, 
 it is liable to be injured by a wound in the back. But near the 
 angle of the rib it passes between the intercostal muscles, and 
 occupies the groove in the lower border of the rib above. Here it 
 gives off a smalt branch, which runs for some distance along the 
 upper border of the rib below, and is lost in the muscles. In 
 some cases I have seen this branch as large as the intercostal 
 itself, and situated so as to be directly exposed to injury in the 
 operation of tapping the chest. 
 
 In its course along the intercostal space, each artery sends 
 branches to the intercostal muscles and the ribs. About midway 
 between the sternum and the spine, each gives off a small branch, 
 which accompanies the lateral cutaneous branch of the intercostal 
 nerve. The continued trunk, gradually decreasing in size, be- 
 comes very small towards the anterior part of the space, and is 
 placed more in the middle of it. Those of the true intercostal 
 spaces inosculate with branches of the internal mammary, and 
 thoracic branches of the axillary; those of the false run between 
 the layers of the abdominal muscles, and anastomose with the 
 epigastric and lumbar arteries. 
 
 The posterior branch passes backwards between the transverse 
 processes of the vertebrae, to the muscles and skin of the back. 
 Each sends an artery through the intervertebral foramen to the 
 spinal cord and its membranes. 
 
 On the right side the intercostal veins terminate in the vena 
 azygos major; on the left, the lower seven or eight terminate 
 
INTERCOSTAL NERVES. 
 
 129 
 
 in the vena azygos minor, the remainder in the left superior 
 intercostal vein. 
 
 These are twelve in number, and are the anterior 
 nerves Stal divisions of the dorsal spinal nerves. Each dorsal 
 nerve (like all the spinal nerves) arises from the spinal 
 cord by two roots, an anterior or motor, and a posterior or sensi- 
 tive. The sensitive root has a ganglion upon it. The two roots 
 unite in the intervertebral foramen and form a compound nerve. 
 After passing through the foramen, Fi g . 26. 
 
 it divides into an anterior and a 
 posterior branch. The posterior 
 branches pass backwards between 
 the transverse processes of the dor- 
 sal vertebrae, and supply the muscles 
 of the back. The anterior branches 
 or the proper intercostal nerves pro- 
 ceed along the intercostal spaces in 
 company with, and immediately be- 
 low, their corresponding arteries. 
 Midway between the spine and the 
 sternum, they give off lateral cu- 
 taneous branches, which supply the 
 skin over the scapula and the thorax. 
 The intercostal nerves terminate in front, in the anterior cutaneous 
 nerves ; the upper six, coming through their respective intercostal 
 spaces, supply the skin over the chest ; the six lower terminate 
 in the front wall of the abdomen, near the linea alba. 
 
 Notice, that the first dorsal nerve ascends nearly perpen- 
 dicularly over the neck of the first rib to form part of the brachial 
 plexus. Before doing so, it sends a nerve to the first intercostal 
 space. This, as a rule, has no lateral cutaneous branch. 
 
 Intercostal absorbent glands. These are situated near the 
 heads of the ribs; there are some between the layers of the inter- 
 costal muscles. They are of small size, and send their absorbent 
 vessels into the thoracic duct. I have seen these intercostal glands 
 enlarged and diseased in phthisis. 
 
 DIAGRAM OF A SPINAL NERVE. 
 
130 PULMONARY ARTERY. 
 
 Bronchial and Small arteries, arising on the right side most fre- 
 cesophageal quently from the first aortic intercostal artery, and on 
 the left from the concavity of the arch of the aorta, 
 accompany the bronchial tube on its posterior aspect into the 
 substance of the lung. Their distribution and office will be con- 
 sidered with the anatomy of the lung. Other arteries proceed from 
 the front of the descending aorta to ramify on the oesophagus, when 
 they inosculate with the cesophageal branches of the inferior thyroid 
 and phrenic arteries. 
 
 Having finished the posterior mediastinum, replace the lung, and 
 turn your attention once more to the great vessels at the root of 
 the heart. 
 
 This vessel is about two inches in length, and conveys 
 Pulmonary the j mpure blood from the heart to the lungs. It pro- 
 ceeds from the right ventricle, crosses obliquely in front 
 of the root of the aorta, and on the left side of that vessel divides 
 into two branches, one for each lung. The right branch passes 
 through the arch of the aorta to the lung ; the left is easily fol- 
 lowed to its lung by removing its investing layer of pericardium. 
 
 Search should be made for a short fibrous cord which connects 
 the commencement of the left pulmonary artery with the concavity 
 of the arch of the aorta. This cord is the remains of the ductus 
 arteriosus, a canal which in foetal life conveyed blood from the 
 pulmonary artery to the aorta. 
 
 Draw towards the left side the first part of the arch of the aorta, 
 and dissect the pericardium from the great vessels at the base of 
 the heart. Thus a good view will be obtained of the trachea and 
 its bifurcation into the two bronchi. Below the division of the 
 trachea the right pulmonary artery is seen passing in front of the 
 right bronchus. The superior vena cava is seen descending in 
 front of, and nearly at right angles to, the right pulmonary artery. 
 The vena azygos is also seen arching over the right bronchus and 
 terminating in the vena cava. Notice, especially, a number of 
 absorbent glands called ' bronchial,' at the angle of bifurcation 
 of the trachea. The situation of these glands in the midst of so 
 many tubes explains the variety of symptoms which may be pro- 
 duced by their enlargement. 
 
CARDIAC PLEXUS. 
 
 131 
 
 The nerves of the heart are derived from the pneu- 
 mogastric and from the cervical ganglia of the sympa- 
 thetic. A general description of them will suffice. The 
 cardiac nerves of the right side descend chiefly behind the arch of 
 
 Cardiac 
 plexus of 
 nerves. 
 
 Fig. 27. 
 
 DIAGRAM SHOWING THE CONSTITUENTS OF THE BOOT OF EACH LUNG, AND THEIR 
 RELATIVE POSITION : ALSO THE POSITION OF THE VALVES OF THE HEART. THE 
 ARROWS INDICATE THE DIRECTION IN WHICH AORTIC AND MITRAL MURMURS ARE 
 PROPAGATED. 
 
 the aorta ; those of the left chiefly in front of the arch. The 
 nerves from both sides, however, converge to form a plexus called 
 the * cardiac? From this two secondary plexuses proceed ; the 
 superficial and the deep cardiac plexus. The superficial one lies 
 
 K 2 
 
132 DISSECTION OF THE HEART. 
 
 more in front of the aorta : the deep plexus is between the arch 
 of the aorta and the bifurcation of the pulmonary artery. 
 
 From these plexuses the nerves proceed, in company with the 
 coronary arteries, to the heart. Those which accompany the 
 anterior coronary artery form the ' anterior coronary plexus.' The 
 * posterior coronary plexus ' proceeds with its artery to the posterior 
 part of the heart. 
 
 But it is not an easy matter to trace the nerves into the sub- 
 stance of the heart. For this purpose a horse's heart is the best, 
 and previous maceration in water is desirable. The nerves in the 
 substance of the heart are peculiar in this respect ; that they pre- 
 sent minute ganglia in their course, which are presumed to preside 
 over the rhythmical contractions of the heart.* 
 Constituents Draw aside the margin of the right lung ; divide the 
 of the root of superior vena cava above the vena azygos, and turn 
 each lung. down the lower part. Remove the layer of pericardium 
 which covers the pulmonary veins, and the constituent parts of the 
 root. of the right lung will be exposed. It is composed of the 
 pulmonary artery, the pulmonary veins, bronchus, bronchial vessels, 
 anterior and posterior pulmonic plexus, and some lymphatics. The 
 following is the disposition of the large vessels forming the root of 
 the lung. In front are the two pulmonary veins : behind the 
 veins are the subdivisions of the pulmonary artery ; behind the 
 artery are the divisions of the bronchus. From above downwards 
 they are disposed thus: On the right side we find 1st, the 
 bronchus ; 2nd, the artery ; 3rd, the veins. On the left, we find : 
 1st, the artery; 2nd, the bronchus; 3rd, the veins, as shown in 
 fi^. 27. 
 
 DISSECTION OF THE HEAKT. 
 
 The heart is conical in form, and more or less convex on its 
 external aspect. It is situated obliquely in the chest, having its 
 base directed upwards and to the right ; its apex downwards and 
 to the left. Notice the longitudinal grooves on the upper and 
 
 * For the demonstration of the nerves of the heart, the student should see the 
 beautiful dissections by Pettigrew in the Museum of the Koyal College of Surgeons. 
 
DISSECTION OF THE HEART. 133 
 
 lower surfaces of the heart, indicating the divisions of the ven- 
 tricles, and the circular groove near the base, indicating the sepa- 
 ration between the ventricles and auricles. These grooves are 
 occupied by the coronary vessels and by more or less fat. 
 
 The average weight of the heart is from ten to twelve 
 ounces in the male, and from eight to ten in the female ; 
 but much depends upon the size and condition of the body gene- 
 rally. As a rule, it may be stated that the heart gradually in- 
 creases in length, breadth, and thickness, from childhood to age.* 
 
 The heart is a double muscular organ ; that is, it is composed 
 of two hearts, a right and a left, separated by a septum. Each 
 consists of an auricle and a ventricle, which communicate by a 
 wide orifice : the right heart propels the blood through the lungs, 
 and is called the pulmonic ; the left propels the blood through the 
 body, and is called the systemic. These two hearts are not placed 
 apart, because important advantages result from their union : by 
 being enclosed in a single bag they occupy less room in the chest ; 
 and the action of their corresponding cavities being precisely syn- 
 chronous, their fibres, mutually intermixing, contribute to their 
 mutual support. The cavities of the heart should now be 
 examined in the order in which the blood circulates through them. 
 
 This is situated at the right side of the base of the 
 e ' heart, and forms a quadrangular cavity between the 
 two venas cavae, from which it receives the blood. From its front 
 a small pouch projects towards the left, and overlaps the root of 
 the aorta ; this part is termed the appendix of the auricle, and 
 resembles a dog's ear in shape ; unde nomen. 
 
 To see the interior, make a horizontal incision through the 
 anterior wall from the apex of the appendix, transversely across 
 the cavity : from this make another upwards at right angles into 
 the superior vena cava. Observe that the interior is lined by a 
 polished membrane called the f endocardium, and that it is 
 everywhere smooth except in the appendix, where the muscular 
 fibres are collected into bundles, called, from their resemblance to 
 the teeth of a comb, ' musculi pectinati.' They radiate from the 
 
 * Consult Bizot, Mm. de la Soc. M6d. d'Obser. de Paris, torn. i. 1836. 
 
134 DISSECTION OF THE HEART. 
 
 auricles to the edges of the auriculo-ventricular opening. Examine 
 carefully the openings of the two venae cavse : they are not directly 
 opposite to each other ; the superior is situated on a plane rather 
 in front of the inferior, that the streams of blood may not meet. 
 
 Fig. 28. 
 
 Auriculo-ventricular orifice . 
 
 Fossa ovalis 
 
 Opening of the coronary vein 
 Line of Eustachian valve . 
 
 DIAGRAM OF THE INTERIOR OF THE RIGHT AURICLE. 
 
 The inferior cava, after passing through the tendinous centre of 
 the diaphragm, makes a slight curve to the left before it opens 
 into the auricle, that the stream of its blood may be directed 
 towards the auriculo-ventricular opening. The orifice of each vena 
 cava is nearly circular, and surrounded by muscular fibres continuous 
 with those of the auricle. 
 
 The internal wall of the auricle is formed by the ( septum 
 auricularum.' Upon this septum, above the orifice of the vena 
 cava inferior, is an oval depression (fossa ovalis\ bounded by a 
 prominent border (annulus ovalis). This depression indicates 
 the remains of the opening (foramen ovate) through which the 
 auricles communicated in foetal life. After birth this opening 
 closes ; but if the closure is imperfect, the stream of dark blood in the 
 right auricle mixes with the florid blood in the left, and occasions 
 what is called 'morbus cceruleus.' 9 A valvular communication, 
 however, not unfrequently exists between the auricles in this 
 situation which is not attended with indications of this disease. 
 
 Extending from the anterior margin of the vena cava inferior to 
 
DISSECTION OF THE HEART. 135 
 
 the anterior border of the fossa ovalis, is seen a thin fold of the 
 lining membrane of the heart : it is the remains of what was, in 
 foetal life, the Eustachian* valve. The direction of this valve is 
 such that it directs the current of blood from the inferior cava 
 towards the foramen ovale. It is a valve of considerable size in 
 the foetus, and contains a few muscular fibres ; but after birth it 
 diminishes, being no longer required. 
 
 To the left of the Eustachian valve, that is, between its remains 
 and the auriculo-ventricular opening, is the orifice of the coronary 
 vein; it is covered by a semicircular valve, called ' valvula The- 
 besiij to prevent regurgitation of the blood during the auricular 
 contraction. Here and there upon the posterior wall of the auricle 
 may be observed minute openings called 'foramina Thebesii : ' 
 they are the orifices of small veins returning blood from the sub- 
 stance of the heart. Lastly, to the left, and rather in front of the 
 orifice of the vena cava inferior, is the auriculo-ventricular opening. 
 It is oval in form, and will admit the passage of three fingers. 
 
 This forms the right border and about two-thirds of 
 Right yen- ^ e front surface of the heart. To examine its interior, 
 
 tricle. 
 
 a triangular flap should be raised from its anterior wall. 
 The apex of this flap should be below : one cut along the right 
 edge of the ventricle, the other along the line of the ventricular 
 septum. Observe that the wall of the ventricle is much thicker 
 than that of the auricle. The cavity of the ventricle is conical, 
 with its base upwards and to the right. From its walls project 
 bands of muscular fibres (columnaB carnea?) of various length and 
 thickness, which cross each other in every direction ; this muscular 
 network is generally filled with coagulated blood. Of these 
 columns carnese there are three kinds : one stands out in relief 
 from the ventricle ; another is attached to the ventricle by their 
 extremities only, the intermediate portion being free ; a third, and 
 by far the most important set, called 'musculi papillares? is fixed 
 by one extremity to the wall of the ventricle, while the other 
 extremity gives attachment to the fine tendinous cords (cordce 
 tendinece) which regulate the action of the tricuspid valve. The 
 
 * Eustachius, Libell. de vena sine pari. 
 
136 DISSECTION OP THE HEART. 
 
 number of these niusculi papillares is equal to the number of the 
 chief divisions of the valve ; consequently there are three in the 
 right and two in the left ventricle. Of those in the right ventricle, 
 one proceeds from the septum. 
 
 There are two openings in the right ventricle. One, the auriculo- 
 ventricular, through which the blood passes from the auricle, is 
 oval in form and placed at the base of the ventricle. It is sur- 
 rounded by a ring of fibrous tissue, to which is attached the tri- 
 cuspid valve. From the upper and front part of the ventricle, a 
 smooth passage (' infundibulum' or * conus arteriosus') leads to 
 the opening of the pulmonary artery. It is situated to the left 
 and in front of the auriculo-ventricular, and about three-fourths of 
 an inch higher. 
 
 This is situated at the right auriculo-ventricular 
 opening, and consists of three principal triangular flaps, 
 and besides these of intermediate flaps of smaller size. 
 Like all the valves of the heart, it is formed by a fold of the lining 
 membrane ('endocardium') of the heart, strengthened by fibrous 
 tissue, in which muscular fibres may be demonstrated. The base 
 of the valve is attached to the tendinous ring round the opening ; 
 its segments lying in the cavity of the right ventricle. Of its 
 three principal flaps, the largest is so placed that when not in 
 action, it partially covers the orifice of the pulmonary artery : 
 another lies behind the anterior wall of the ventricle, and the third 
 rests upon the septum ventriculorum. 
 
 Observe the arrangement of the tendinous cords which regulate 
 the action of the valve. First, they are all attached to the ven- 
 tricular surface of the valve. Secondly, the tendinous cords pro- 
 ceeding from a given papillary muscle are attached to the adjacent 
 halves of two of the larger flaps, and to a smaller intermediate 
 one ; consequently, when the ventricle contracts, and the papillary 
 muscle also, the adjacent borders of the flaps will be approximated. 
 Thirdly, to insure the strength of every part of the valve, the 
 tendinous cords are inserted at three different points of it in 
 straight lines ; accordingly, they are divisible into three sets. 
 Those of the first, which are three or four in number, are attached 
 
DISSECTION OF THE HEART, 137 
 
 to the base of the valve ; those of the second, from four to six, 
 proceed to the middle of it ; those of the third, which are the most 
 numerous, are attached to its free margin.* 
 
 Pulmonar or These are three membranous folds situated at the 
 semilunar orifice of the pulmonary artery. Their convex borders 
 are attached to the fibrous ring at the root of the 
 artery ; their free edges, which look upwards, present a festooned 
 border, in the centre of which is a small cartilaginous body called 
 the f nodulus ' or ' corpus ArantiiS The use of these bodies is 
 obvious. Since the valves are semilunar, when they fall together 
 they would not exactly close the artery ; there would be a space of a 
 triangular form left between them in the centre, just as there is when 
 we put the thumb, fore, and middle fingers together. This space is 
 filled up by these nodules, so that the closure becomes complete. 
 
 The valves are composed of a fold of the ' endocardium,' or 
 lining membrane of the heart, and contained between the folds is 
 a thin layer of fibrous tissue, which is prolonged from the ten- 
 dinous ring at the orifice of the artery. This layer of fibrous 
 tissue, however, reaches the free edge of the valve at three points 
 only; namely, at the centre, or corpus Arantii, and at each 
 extremity. Between these points it stops short, and leaves a 
 crescent-shaped portion of the valve thinner than the rest, and 
 consisting simply of endocardium. This crescent-shaped portion 
 (called the c lunula ') is not wholly without fibrous tissue, for a 
 thin tendinous cord runs along its free edge, to give it additional 
 strength to resist the impulse of the blood. Behind each of the 
 valves the artery bulges and forms three slight dilatations called 
 
 * The best mode of showing the action of the valve is to introduce a glass tube into 
 the pulmonary artery, and then to pour water through it into the ventricle until the 
 cavity is quite distended. By gently squeezing the ventricle in the hand, so as 
 artificially to imitate its natural contraction, the tricuspid valve will flap back like a 
 flood-gate, and close the auriculo-ventricular opening. In this way one can understand 
 how, when the ventricle contracts, the blood catches the margin of the valve, and by 
 its pressure gives it the proper distention and figure requisite to block up the aperture 
 into the auricle. It is obvious that the tendinous cords will prevent the valve from 
 being pushed too far back into the auricle; and this purpose is assisted by the papillary 
 muscles, which nicely adjust the degree of tension of the cords at a time when they 
 would otherwise be too much slackened by the contraction of the ventricle. 
 
138 DISSECTION OF THE HEART. 
 
 the 'sinuses of Valsalva.' These, we shall presently see, are 
 more marked at the orifice of the aorta. 
 
 The action of these valves is obvious. During the contraction 
 of the ventricle the valves lie against the side of the artery, and 
 offer no impediment to the current of blood ; during its dilatation, 
 the elasticity of the distended artery would force back the column 
 of blood, but that the valves, being caught by the refluent blood, 
 bag, and fall together so as to close the tube. The greater the 
 pressure, the more accurate is the closure. The coats of the 
 artery are very elastic and yielding, while the valve, like the 
 circumference to which it is attached, is quite unyielding ; conse- 
 quently, when the artery is distended by the impulse of the blood, 
 its wall is removed from the contact of the free margin of the 
 valves, and these are the more readily caught by the retrograde 
 motion of the blood. The force of the reflux is sustained by the 
 tendinous part of the valves, and by the muscular wall of the 
 ventricle (probably in a state of contraction), as shown by Mr. 
 Savory. According to Haller, the valves are capable of sustaining 
 a weight of sixty-three pounds before they give way. The thinner 
 portions (lunulce) become placed so as to lie side by side, each one 
 with that of the adjacent valve. This may be demonstrated by 
 filling the artery with water. 
 
 This is situated at the left side and posterior part of 
 the base of the heart, and is somewhat smaller than 
 the right auricle. It is quadrilateral and receives the four pul- 
 monary veins, two on either side, which return the purified blood 
 from the lungs. From its upper and left side, the auricular ap- 
 pendage projects towards the right, curling over the root of the 
 pulmonary artery. The auricle should be opened by a horizontal 
 incision from one pulmonary vein to another : from this a second 
 should be made into the appendix. Its interior is smooth and flat, 
 excepting in the appendix, which contains the ' musculi pectinati.' 
 Notice the openings of the four pulmonary veins. Upon the sep- 
 tum between the auricles is a depression indicating the remains of 
 the foramen ovale. At the lower and front part of the auricle is the 
 auriculo-ventricular opening. It is oval, with its long axis nearly 
 transverse, and in the adult will admit the passage of two fingers. 
 
DISSECTION OF THE HEART. 139 
 
 This occupies the left border, and forms the apex of 
 Left ventricle. . , , f ^ . , . , r . . -. . . , 
 
 the heart. One third ot it only is seen on the anterior 
 
 surface, the rest being on its posterior. To examine the interior, 
 raise a triangular flap, with the apex below, from its front wall. 
 Observe that it is about three times as thick as that of the right 
 ventricle, and that this thickness gradually diminishes towards the 
 apex. The interior of the left ventricle so closely resembles that 
 of the right that there is no necessity to describe it in detail. 
 The auricula-ventricular valve consists of only two principal 
 flaps : hence its name ( mitral ' or ' bicuspid.' The larger of 
 these flaps is placed between the aortic and auriculo-ventricular 
 orifices. There are only two ' musculi papillares ; ' one attached 
 to the anterior, the other to the posterior wall of the ventricle. 
 They are thicker and their ( cordce tendinece ' stronger than those 
 of the right ventricle, but their arrangement is precisely similar. 
 From the upper and back part of the ventricle, a smooth passage 
 leads to the orifice of the aorta. This orifice is placed rather in 
 front, and to the right side of the auriculo-ventricular opening ; 
 but the two orifices are close together, and only separated by the 
 larger flap of the mitral valve. The aortic orifice is guarded by 
 three semilunar valves, of which the arrangement, structure, and 
 mode of action are similar to those of the pulmonary artery. 
 Their framework is proportionately stronger, consistently with the 
 greater strength of the left ventricle, and the greater impulse of 
 the blood. In the ( sinuses of Valsalva ' are observed the orifices 
 of the two coronary arteries. 
 
 At the openings between the auricles and ventricles, 
 mgs ' and also at the commencement of the aorta and pul- 
 monary artery, we find fibrous rings. These rings serve as fixed 
 points for the attachment of the muscular fibres of the heart, the 
 tricuspid and the mitral valves. The rings on the left side are 
 stronger than those on the right. 
 
 The fibrous rings at the arterial orifices present three 
 
 of the great festoons with concavities directed upwards. These 
 
 arteries to festoons give attachment to the middle coat of the 
 
 artery above, to the muscular fibres of the heart below, 
 
 and internally to the tendinous fibres of the valves. The vessels 
 
140 DISSECTION OF THE HEART. 
 
 are also connected to the heart by the serous layer of the peri- 
 cardium, and by a continuation of the lining membrane (endo- 
 cardium) of the ventricle. 
 
 The heart is supplied with blood by the two coronary 
 Coronary arteries, a right or posterior, and a left or anterior. 
 Both arise from the aorta just above the semilunar 
 valves, and at such a distance as always to admit the passage of 
 blood : both run in the furrows between the ventricles and 
 auricles : both are accompanied by branches of the coronary vein, 
 and by the cardiac nerves. 
 
 The anterior, or left coronary artery, the smaller of the two, . 
 arises from the left side of the aorta. It appears on the left of 
 the pulmonary artery, and then runs down the inter- ventricular 
 furrow on the anterior surface of the heart to the apex, where it 
 inosculates with the posterior coronary. In this course, its prin- 
 cipal branch turns to the left, along the furrow between the left 
 ventricle and auricle, and then communicates at the back of the 
 heart with a branch of the posterior coronary. 
 
 The posterior or right coronary artery arises from the right 
 side of the aorta, and passes down between the pulmonary artery 
 and the appendix of the right auricle! It turns to the right along 
 the furrow between the right ventricle and auricle to the back of 
 the heart, whence it inosculates with the horizontal branch of the 
 left coronary. Besides this, it sends a branch down the inter- 
 ventricular furrow at the back of the heart to the apex, where it 
 communicates with the left coronary. 
 
 Thus the coronary arteries form two circles about the heart: 
 the one, horizontal, runs round the base of the heart, in the 
 furrow between the auricles and ventricles. The other, perpen- 
 dicular, runs in the furrow between the ventricles. 
 
 The veins corresponding to the coronary arteries 
 terminate in a single trunk e the coronary sinus ' 
 which opens into the right auricle between the remains 
 of the Eustachian valve and the auriculo-ventricular opening. The 
 orifice of the vein is guarded by a valve, to prevent regurgitation 
 of the blood. 
 
DISSECTION OF THE HEART. 141 
 
 The muscular fibres of the heart are of the striped 
 ofthe raus- variety, but differ from ordinary striped muscular 
 cular fibres tissue, in being somewhat smaller, destitute of sarco- 
 lemma, and branched. Most of the fibres are attached 
 by both extremities to the fibrous rings of the heart. The fibres 
 of the auricles are distinct from those of the ventricles. They 
 consist of a superficial layer common to both cavities, and a 
 deeper layer proper to each. The superficial fibres run trans- 
 versely across the auricles, and are most marked on the anterior 
 surface ; some pass into the septum. Of the deeper fibres, some 
 run in circles chiefly round the auricular appendages and the 
 entrance of the great veins, upon which a few may be traced for 
 a short distance ; others run over the auricles, and are attached 
 in front and behind to the auric ulo-ventricular rings. 
 
 Of the ventricular fibres, some are common to both ventricles, 
 others proper to each. The septum is formed principally by the 
 fibres of the left. The superficial fibres take a more or less spiral 
 course from the base towards the apex of the heart, where they 
 coil round, pass into the interior of the ventricle, and form either 
 the 'carneae columns' or 'musculi papillares.' Most of these 
 fibres are eventually inserted* into the auriculo-ventri cular rings. 
 The circular fibres are chiefly found near the base of the 
 ventricles, and passing round become attached to the rings at the 
 base of the heart.* 
 
 Eeduced to their simplest expression, the ventricles consist of 
 two muscular sacs, enclosed in a third equally muscular. The 
 same may be said of the auricles. 
 
 The average thickness of the right auricle is about 
 one line 5 that of the left, one and a half. The 
 measure must not be taken during the ' rigor mortis.' 
 
 The average thickness of the right ventricle at its thickest part 
 i.e. the base is about two lines : that of the left ventricle at 
 its thickest part i.e. the middle is about half an inch. In the 
 female the average is less. 
 
 * For further information upon this subject, see the article in Todd's Cyclopaedia. 
 Examine also the beautiful and elaborate dissections by Pettigrew, in the Museum of 
 the College of Surgeons. 
 
142 
 
 F03TAL CIRCULATION. 
 
 Peculiarities 
 of foetal 
 heart. 
 
 The heart of the foetus differs from that of the adult 
 
 in the following points : 1. The Eustachian valve is 
 well developed in order to guide the current of blood 
 from the vena cava inferior into the foramen ovale. 2. The 
 
 Fig. 29. 
 
 SUP R v, c 
 
 FORAMEN OVALE 
 
 'LAC ENTA 
 
 SCHEME OF THE FOSTAX CIRCULATION. 
 
 foramen ovale is widely open. 3. The right and left pulmonary 
 arteries are very much contracted, so as to admit very little blood 
 
FCETAL CIRCULATION. 143 
 
 to the lungs. 4. The ductus arteriosus (from the pulmonary artery 
 to the aorta) is open. 5. The right and left ventricles are of equal 
 thickness because they have equal work to do. 
 Circulation of ^ ne um kilical vein, fig. 29, bringing pure blood from 
 the blood in the placenta, enters at the umbilicus, and passes to the 
 MS ' under surface of the liver, where it sends off some small 
 branches to the left lobe. At the transverse fissure it divides into 
 two branches: one, the smaller, termed the 'ductus venosus, 
 passes straight to the inferior vena cava ; the other or right division 
 joins the vena porta, and after ramifying in the liver, returns its 
 blood through the hepatic veins into the inferior vena cava. From 
 the inferior vena cava, the blood enters the right auricle, and this 
 stream (directed by the Eustachian valve) flows through the fora- 
 men ovale into the left auricle. From the left auricle it runs into 
 the left ventricle, and thence through the aorta, into the great 
 vessels of the head and the upper limbs, which are thus supplied 
 by almost pure blood. 
 
 From the head and the upper limbs, the blood returns (impure) 
 through the superior vena cava into the right auricle, and flows 
 into the right ventricle. From the right ventricle it passes through 
 the pulmonary artery, and the s ductus arteriosus, ,' into the third 
 part of the arch of the aorta ; only a very small quantity of it 
 going to the lungs. From the aorta part of the blood is distri- 
 buted to the pelvis and lower extremities ; and part is conveyed 
 through the umbilical arteries to the placenta, where it becomes 
 purified. 
 
 The following changes take place in the circulation after birth : 
 
 1. The umbilical vein becomes obliterated from the second to 
 the fifth day after birth, and subsequently forms the round liga- 
 ment of the liver. 
 
 2. The ductus venosus also becomes closed about the same period. 
 
 3. The foramen ovale and ductus arteriosus become completely 
 closed from the sixth to the tenth day. 
 
 4. The pulmonary arteries enlarge and convey impure blood 
 to the lungs. These organs during foetal life receive only a small 
 quantity of blood from these arteries. 
 
144 STRUCTURE OF THE LUNGS. 
 
 5. The hypogastric arteries become obliterated from the fourth 
 or fifth day after birth. 
 
 STKUCTUKE OF THE LUNGS. 
 
 The lungs are very vascular, spongy organs, in which the blood is 
 purified by exposure to atmospheric air. Their situation and shape 
 iave been already described (p. 119). We have now to examine 
 their general structure. 
 
 The lungs are composed of cartilaginous and membranous tubes, 
 of which the successive subdivisions convey the air into closely- 
 packed minute cells, called the ' air vesicles ; ' of the ramifications 
 of the pulmonary artery and veins ; of the bronchial vessels con- 
 cerned in their nutrition ; of lymphatics and nerves. These com- 
 ponent parts are united by areolar tissue, and covered externally 
 by pleura. The point at which they respectively pass in and out 
 is called the * root ' of the lung. 
 
 The lungs are the lightest organs in the body, and float in water. 
 When entirely deprived of air, they sink. This is observed in 
 certain pathological conditions ; e.g. when one lung is compressed 
 by effusion into the chest, or rendered solid by inflammation. 
 
 When an opening is made into the chest, the lung, 
 oftheTun lty ^ich was in contact with the ribs, immediately recedes 
 from them, and, provided there be no adhesions, gra- 
 dually contracts. If the lungs be artificially inflated, either in or 
 out of the chest, we observe that, left to themselves, they spon- 
 taneously expel a part of the air. This constant disposition to 
 contract, in the living and the dead lung, is owing to the elastic 
 tissue in the bronchial tubes and the air-cells ; but more especially 
 to a layer of delicate elastic tissue on the surface of the lung, which 
 has been described by some anatomists as a distinct coat, under 
 the name of the second or inner layer of the pleura.* 
 
 The lungs are of a livid red or violet colour ; they 
 often present a mixture of tints, giving them a marble- 
 
 * In some animals, the seal especially, the elasticity of this tissue is very strongly 
 marked. 
 
STRUCTURE OF THE LUNGS. 145 
 
 like appearance. This is not the natural colour of the organ, since 
 it is produced in the act of dying. It depends upon the stagnation 
 of the venous blood, which the right ventricle still propels into the 
 lungs, though respiration is failing. The tint varies in particular 
 situations in proportion to the accumulation of the blood, and is 
 always the deepest at the back of the lung. But the colour of the 
 proper tissue of the lung apart from the blood which it contains is 
 pale and light grey. This colour is seldom seen except in the 
 lungs of infants who have never breathed, or after death from 
 profuse haemorrhage. 
 
 Upon or near the surface of the lungs, numerous dark spots are 
 observed, which do not depend upon the blood, since they are 
 seen in the palest lungs. They vary in number and size, and 
 increase with age. The source of these discolourations is not 
 exactly known ; but they are probably deposits of minute particles 
 of carbonaceous matter which have been inhaled with the air. 
 
 This is a partly membranous, partly cartilaginous 
 
 tube, which proceeds from the larynx opposite the fifth 
 cervical vertebra, and divides about the third dorsal vertebra 
 into two tubes, called the right and left bronchi, one for each 
 lung. Its length is from four to four and a half inches. Its 
 transverse diameter is about eight or ten lines in the adult, but it 
 varies according to the age of the individual, and the natural 
 volume of the lungs. It is kept permanently open by a series of 
 cartilaginous rings, from sixteen to twenty in number, which 
 extend round the anterior two-thirds of its circumference. These 
 rings are deficient at the posterior part of the tube, where it is 
 completed by fibrous membrane. This deficiency is for the pur- 
 pose of allowing the trachea to expand or contract; and the 
 membranous part of the tube is provided with transverse muscular 
 fibres which can approximate the ends of the rings. 
 
 The two bronchi differ in length, direction and 
 
 diameter. The right, shorter than the left, is about 
 an inch in length, and passes more horizontally to the root of its 
 lung. It is larger in all its diameters than the left ; hence, foreign 
 bodies which have accidentally dropped into the trachea are more 
 
 L 
 
146 STRUCTURE OF THE LUNGS. 
 
 likely to be carried into the right bronchus by the stream of the 
 air. The left bronchus is about two inches in length, and descends 
 more obliquely to its lung than the right. 
 
 The cartilages of the trachea vary in number from sixteen to 
 twenty ; those of the right bronchus from six to eight ; those of 
 the left from nine to twelve. They form about two-thirds of a 
 circle, and resemble a horse-shoe in form. The cartilage at the 
 bifurcation of the trachea is shaped like the letter V; its angle 
 projects into the centre of the main tube, and its sides belong one 
 to each bronchus. 
 
 The cartilages are connected, and covered on their outer and 
 inner surfaces by a tough membrane, consisting of fibrous and 
 yellow elastic tissue. This membrane is attached to the circum- 
 ference of the cricoid cartilage, and is continued through the whole 
 extent of the trachea and the bronchial tubes. Posteriorly, where 
 the cartilages are deficient, it maintains the integrity of the 
 tube ; in this situation, it consists of parallel and closely arranged 
 longitudinal fibres, which are seated immediately beneath the 
 mucous membrane, and raise it into folds. The elasticity of 
 this structure admits of the elongation and contraction of the 
 trachea. 
 
 Between the fibrous and muscular layers of the 
 trachea are a large number of small mucous glands, 
 which are most numerous on the posterior part of the 
 tube. In health, their secretion is clear, not tenacious, and just 
 sufficient to lubricate the air-passages. In bronchitis, they are 
 the sources of the abundant viscid expectoration. 
 
 After removing the fibrous membrane and the 
 fibres^ 1 a tracheal glands from the back of the trachea, we expose 
 a thin stratum of non-striped muscular fibres, some of 
 which extend transversely between the posterior free ends of the 
 cartilages, while others are arranged in longitudinal bundles. By 
 their contraction, they approximate the ends of the cartilages, and 
 diminish the calibre of the tube. 
 
 The mucous membrane lining the air-passages is a continuation 
 from that of the larynx. Its colour in the natural state is nearly 
 
STRUCTURE OF THE LUNGS. 147 
 
 white, but in catarrhal affections it becomes bright red, in con- 
 sequence of the accumulation of blood in the capillary vessels. 
 It is continued into the ultimate air-cells, where it becomes thinner 
 and more transparent. Its surface is lined by a layer of epithe- 
 lium of the ciliated kind, of which the vibratile movement is 
 directed in such a way as to favour the expectoration of the 
 mucus. The ciliated epithelium lining the mucous membrane 
 ceases at the commencement of the air-cells, where it is replaced 
 by the squamous variety. 
 
 At the root of the lung each bronchus divides into two branches, 
 an upper and a lower, corresponding to the lobes of the lung ; on 
 the right side the lower branch sends a small division to the third 
 lobe. The tubes diverge through the lung, and divide into 
 branches, successively smaller and smaller, until they lead to the 
 air-cells. These ramifications do not communicate with each other, 
 they are like the branches of a tree ; hence when a bronchial tube 
 is obstructed, all supply of air is cut off from the cells to which it 
 leads. 
 
 The several tissues, cartilaginous, fibrous, muscular, mucous, and 
 glandular, which collectively compose the air-passages, are not 
 present in equal proportions throughout all their ramifications, but 
 each is placed in greater or less amount where it is required. The 
 cartilaginous rings, necessary to keep the larger bronchi per- 
 manently open, become in the smaller tubes fewer and less regular 
 in form : as the subdivisions of the tubes multiply, the cartilages 
 consist of small pieces placed here and there, they become less 
 and less firm, and finally disappear altogether. The walls of the 
 air-passages, when no longer traceable by the naked eye, are 
 entirely membranous, being formed of fibrous, elastic, and muscular 
 tissues. 
 
 The surface of the healthy lung is marked by faint 
 f white lines, which map it out into a number of angular 
 spaces of various size. These spaces indicate the lobules 
 of the lung. Each lobule is a lung in miniature. Whoever 
 understands the structure of a single lobule, understands the struc- 
 ture of the entire lung. The lobules are connected by fine areolar 
 
 J. 2 
 
148 
 
 STRUCTURE OF THE LUNGS. 
 
 tissue, called ' interlobular,' which is everywhere soft and elastic to 
 allow the free expansion of the organ. The cells of this tissue 
 have no communication with the air-vesicles unless the latter be 
 ruptured by excessive straining, and then this intermediate tissue 
 becomes inflated with air, and gives rise to 6 interlobular emphy- 
 sema.' When infiltrated with serum it constitutes ' oedema ' of 
 the lungs. 
 
 Each lobule receives a small bronchial tube, which subdivides 
 into smaller branches. Thus reduced in size, the walls of the tubes 
 
 Fig. 30. 
 
 Fig. 31. 
 
 ULTIMATE AIR-CELLS OF THE LUNG (FROM KOLLIKER). MAGNIFIED TWENTY -FIVE TIMES 
 
 no longer present traces of cartilaginous tissue, but are composed 
 of a delicate elastic membrane upon which the capillaries ramify in 
 a very minute network.* Each tube finally leads into an irregular 
 passage (intercellular passage), from which proceed on all sides 
 numerous dilatations : these are the air-cells, which vary from the 
 ^--J-o-th to the y'-g-th of an inch in diameter (fig. 31). The air-cells 
 themselves present a number of shallow depressions, separated 
 by somewhat prominent partitions, so that their interior has a 
 
 * In phthisis the expectoration contains some of the debris of this elastic frame- 
 work of the air-vesicles ; they can be seen under the microscope. This is not a bad 
 test of the character of the sputa. 
 
STRUCTURE OF THE LUNGS. 149 
 
 honeycomb appearance, as shown in % 31. The purpose of this is 
 to increase the extent of surface upon which the capillaries may, 
 ramify. The structure of the minute air-cell of the human 
 lung is in all respects similar to the large respiratory sac of the 
 reptile. 
 
 The branches of the pulmonary artery subdivide with 
 ^ e bronchial tubes. Their ultimate ramifications 
 spread out in such profusion over the air-cells, that a 
 successfully injected lung appears a mass of the finest network of 
 capillaries. This network is so close that the interstices are even 
 narrower than the vessels, which are on an average about -j^-Q-th 
 of an inch in diameter. The blood and air are not in actual 
 contact. Nothing, however, intervenes but the wall of the cell 
 and the capillary vessel, which are such delicate structures that 
 they oppose no obstacle to the free interchange of gases by which 
 the blood is purified. This purification is effected by the taking 
 in of oxygen, and the elimination of carbonic acid and watery 
 vapour. The most complete purification takes place in the single 
 layer of capillaries between the folds of membrane projecting into 
 the cell ; for in this situation both sides of these vessels are ex- 
 posed to the action of the air. The blood, circulating in steady 
 streams through this capillary plexus, returns through the pulmo- 
 nary veins. These, at first extremely minute, gradually coalesce 
 into larger and larger branches, which accompany those of the 
 arteries, and finally emerge from the root of the lung by two 
 large trunks which carry the pure florid blood to the left auricle 
 of the heart. 
 
 From this outline of the anatomy of the lung, we see that the 
 organ is so constructed as, in a given space, to allow the largest 
 possible quantity of impure blood to be brought in communication 
 with the largest possible quantit} 7 of atmospheric air. It is diffi- 
 cult to conceive how any apparatus could be better adapted to the 
 object in view. A stratum of blood of great superficial extent is 
 exposed to an equal stratum of air, and these strata of contiguous 
 fluids are contained in the interior of an organ so small as to lie 
 within the compass of the chest. 
 
150 DISSECTION OF THE PHARYNX. 
 
 These are small arteries, two or more in number for 
 Bronchial e&c fa l un g. The right arises either from the first aortic 
 
 8/1*1" 6I*1GS 
 
 intercostal or, conjointly with the left bronchial, from the 
 concavity of the arch of the aorta. They enter the lung behind 
 the divisions of the bronchi, which they accompany. They are 
 the proper nutritive vessels of the organ. The old anatomists 
 called them the ( vasa privata pulmonum,' to distinguish them 
 from the ( vasa publica pulmonum ' namely, the pulmonary 
 arteries. The former provide f pro existentia privata pulmo- 
 num ; ' the latter ' pro bono publico totius organism^ The 
 bronchial vessels are distributed in various ways ; some of their 
 branches supply the coats of the air-passages and the large blood- 
 vessels, others the interlobular tissue, and a few reach the surface 
 of the lung, and ramify beneath the pleura. The right bronchial 
 veins terminate in the vena azygos ; the left, in the superior inter- 
 costal vein. 
 
 The nerves of the lung are derived from the pneumogastric and 
 the sj^mpathetic. They enter with the bronchial tubes, forming a 
 plexus in front and behind them (anterior and posterior pulmonary 
 plexus). 
 
 The absorbents of the lung form a network upon its surface 
 and in the interlobular spaces. They all pass through the bron- 
 chial glands. Of these, the larger are situated about the bronchi 
 near the root of the lung, particularly under the bifurcation of the 
 trachea. 
 
 DISSECTION OP THE PHAEYNX. 
 
 To obtain a view of the pharynx, cut through the trachea, oeso- 
 phagus, and the great vessels of the neck, and then separate them 
 from the bodies of the cervical vertebra, to which they are loosely 
 connected. The base of the skull should be sawn through between 
 the vertebral column and the styloid processes of the temporal 
 bones, so as to leave the pharynx and larynx attached to the anterior 
 half of the section. Horsehair should be introduced through the 
 mouth and oesophagus to distend the pharynx. 
 
 The term ' pharynx ' is applied to that part of the alimentary 
 
DISSECTION OF THE PHARYNX. 151 
 
 canal which receives the food after it has been masticated, and 
 propels it downwards into the oesophagus. It is a funnel-shaped 
 muscular bag, about four and a half inches in length. Its broad- 
 est portion is situated opposite the os-hyoides. Its upper part is 
 attached to the basilar process of the occipital bone ; from thence 
 it extends perpendicularly as low as the cricoid cartilage, or the 
 level of the fifth cervical vertebra, where the continuation of it 
 takes the name of f oesophagus.' The bag is connected behind to 
 the bodies of the cervical vertebrae by loose areolar tissue which 
 never contains fat. In abscesses at the back of the pharynx, the 
 matter is seated in this tissue. Parallel with and close to its 
 sides run the internal carotid arteries. Its dimensions are not 
 equal throughout. Its breadth at the upper part is just equal to 
 that of the posterior openings of the nose ; here it is only required 
 to transmit air : but it becomes much wider in the situation where 
 it transmits the food that is, at the back of the mouth : thence 
 it gradually contracts to the oesophagus. The pharynx, therefore, 
 may be compared to a funnel communicating in front by wide 
 apertures with the nose, the mouth, and the larynx ; while the 
 oesophagus represents the tube leading from its lower end. The 
 upper part of the funnel forms a cul-de-sac at the basilar process 
 of the occipital bone. At this part there is, on each side, the 
 opening of a narrow canal, called the ' Eustachian tube,' through 
 which air passes to the tympanum of the ear.* 
 
 Before the muscles of the pharynx can be examined, we must 
 remove a layer of condensed cellular membrane, called by some 
 anatomists the ' pharyngeal fascia.' It is a layer of deep cervical 
 
 * Observe that the pharynx conducts to the oesophagus by a gradual contraction 
 of its channel. This transition, however, is in some cases sufficiently abrupt to 
 detain a foreign body, such as a morsel of food more bulky than usual, at the top 
 of the oesophagus. If such a substance become firmly impacted in this situation, 
 one can readily understand that it will not only prevent the descent of food into 
 the stomach, but that it may occasion, by its pressure on the trachea, alarming 
 symptoms of suffocation. Supposing that the obstacle can neither be removed by 
 the forceps, nor pushed into the stomach by the probang, it may then become 
 necessary to extract it by making an incision into the oesophagus on the left side of 
 the neck. 
 
152 
 
 DISSECTION OF THE PHARYNX. 
 
 fascia behind the pharynx, and must not be confounded with the 
 proper pharyngeal c aponeurosis,' which intervenes between its 
 muscular and mucous walls. 
 
 At the back of the pharynx, near the base of the skull, we find 
 
 Fig. 32. 
 
 Tensor palati. 
 Levator palati. 
 
 Orbicnlaris oris . 
 
 Pterygo-maxillary 
 
 ligament . . 
 
 Mylo-hyoidens . 
 
 Os-hyoides . . . 
 Thyro-hyoid liga- 
 ment . 
 
 Pomum Adami . 
 
 Cricoid cartilage . 
 Trachea 
 
 MUSCLES OF THE PHAEYNX. 
 
 Glosso-pharyngeal n. 
 Stylo-pharyngeus. 
 
 Superior laryngeal 
 n. and a. 
 
 External laryngeal n. 
 Crico-thyroid. - 
 
 Inferior laryngeal n. 
 (Esophagus. 
 
 some absorbent glands. They sometimes enlarge, and form a per- 
 ceptible tumour in the pharynx. 
 
 In removing the fascia from the pharyngeal muscles, notice 
 
DISSECTION OF THE PHARYNX. 153 
 
 that a number of veins ramify and communicate in all directions. 
 They constitute the ^ pharyngeal venous plexus,' and terminate 
 in the internal jugular. 
 
 Constrictor They are three in number, and arranged so that they 
 muscles of overlap each other i. e. the inferior overlaps the 
 the pharynx. middlej and the ^dle the superior (fig. 32). They 
 have the same attachments on both sides of the body ; and the 
 fibres from the right and left meet together, and are inserted in 
 the mesial line, the insertion being marked by a white longitudinal 
 line called the ' raphe.' 
 
 The inferior constrictor arises from the side of the cricoid and 
 thyroid cartilages. Its fibres expand over the lower part of the 
 pharynx. The superior fibres ascend ; the middle run transversely ; 
 the inferior descend, and are identified with the oesophagus. Be- 
 neath its lower border the recurrent laryngeal nerve enters the 
 larynx. 
 
 The middle constrictor arises from the upper edge of the 
 greater cornu of the os-hyoides, from its lesser cornu, and part of 
 the stylo-hyoid ligament. Its fibres take different directions, so 
 that with those of the opposite muscle they form a lozenge. The 
 lower angle of the lozenge is covered by the inferior constrictor ; 
 the upper angle ascends nearly to the basilar process of the occi- 
 pital bone, and terminates upon the pharyngeal aponeurosis. 
 The external surface of the muscle is covered at its origin by the 
 hyo-glossus. 
 
 Between the middle and inferior constrictors, the superior 
 laryngeal artery and nerve perforate the thyro-hyoid membrane to 
 supply the larynx. 
 
 The superior constrictor arises from the hamular process of 
 the sphenoid bone, and from the lower part of its internal ptery- 
 goid plate ; from the pterygo-maxillary ligament (which connects 
 it with the buccinator); from the mylo-hyoid ridge of the lower 
 jaw, and from the side of the tongue. The fibres pass backwards 
 to the mesial line : some of them are inserted through the medium 
 of the pharyngeal aponeurosis into the basilar process. 
 
 The upper border of the superior constrictor presents on either 
 
154 DISSECTION OF THE PHARYNX. 
 
 side a free semilunar edge with its concavity upwards, so that 
 between it and the base of the skull a space is left in which the 
 muscle is deficient (fig. 32). Here the pharynx is strengthened 
 and walled in by its own aponeurosis. The space is called the 
 ' sinus of Morgagni ; ' and in it, with a little dissection, we expose 
 the muscles which raise and tighten the soft palate : i. e. the levator 
 palati, and the tensor palati. The Eustachian tube opens into the 
 pharynx just here. Observe that the fibres of the stylo-pharyngeus 
 pass in between the superior and middle constrictors, and expand 
 upon the side of the pharynx ; some of them mingle with those of 
 the constrictors, but most of them are inserted into the posterior 
 margin of the thyroid cartilage. 
 
 Pharyngeal ^ke P nai y n g ea l aponeurosis intervenes between the 
 membrane or muscles and the mucous membrane of the pharynx. It 
 aponeurosis. ig attaclied to the fcasilar process of the occipital bone, 
 and to the points of the petrous portions of the temporal bones. 
 It maintains the strength and integrity of the pharynx at its 
 upper part, where the muscular fibres are deficient; but it 
 gradually diminishes in thickness as it descends, and is finally lost 
 on the oesophagus. Notice the number of mucous glands upon 
 this aponeurosis, especially near the base of the skull and the 
 Eustachian tube. These glands sometimes enlarge and occasion 
 deafness from pressure on the tube. 
 
 Openings ^ay P en the P nar j nx by a longitudinal incision, and 
 
 into the observe the seven openings leading into it (fig. 33) : 
 1. The two posterior openings of the nares. 2. On 
 either side of them, near the lower turbinated bones, are the 
 openings of the Eustachian tubes : below the nares is the soft 
 palate, with the uvula. 3. Below the soft palate is the communi- 
 cation with the mouth, called the ( isthmus faucium.' On either 
 side of this are two folds of mucous membrane, constituting the 
 anterior and posterior half-arches of the palate ; between them are 
 the tonsils. Below the isthmus faucium is the epiglottis, which is 
 connected to the base of the tongue by three folds of mucous 
 membrane. 4. Below the epiglottis is the aperture of the larynx. 
 5. Lastly, is the opening into the oesophagus. 
 
DISSECTION OF THE PHARYNX. 
 
 1.55 
 
 All these parts are lined by mucous membrane common to the 
 entire tract of the respiratory passages and the alimentary canal. 
 But this membrane presents characteristic differences in the dif- 
 
 Fig. 33. 
 
 Eustachian tube. 
 Levator palati m. 
 
 Tensor palati m. 
 Hamular process. 
 
 Posterior palatine arch. 
 Tonsil. 
 
 Anterior palatine arch. 
 
 Epiglottis. 
 Aryteno-epiglottidean fold. 
 
 Opening into the larynx. 
 
 Opening into the oesophagus 
 
 VIEW OF THE PHARYNX LAID OPEN FROM BEHIND. 
 
 ferent parts of these channels, according as they are intended as 
 passages for air or for food. The mucous membrane of the pharynx 
 above the velum palati, being intended to transmit air only, is very 
 
156 SOFT PALATE. 
 
 delicate in its texture, and lined by ciliated epithelium like the rest 
 of the air-passages. But opposite the fauces, the mucous membrane 
 in every respect resembles that of the mouth, and is provided with 
 squamous epithelium. At the back of the larynx the membrane is 
 corrugated into folds, to allow the expansion of the pharynx during 
 the passage of the food. 
 
 The membrane is lubricated by a plentiful secretion from the 
 numerous mucous glands which are situated in the submucous 
 tissue throughout the whole extent of the pharynx, more particularly 
 in the neighbourhood of the Eustachian tubes. 
 Posterior These are two oval openings, each of which is about 
 
 openings of an inch long, and half an inch in the short diameter. 
 They are bounded above by the body of the sphenoid 
 bone, externally by its pterygoid plate, below by the horizontal 
 portion of the palate bone ; they are separated from each other by 
 the vomer. 
 
 If you remove the mucous membrane from the posterior part of 
 the roof of the nose, and the top of the pharynx, you will find beneath 
 it much fibrous tissue. Hence polypi growing from these parts 
 are generally of a fibrous nature. 
 
 This name is given to the opening by which the 
 
 fauchvm mouth communicates with the pharynx. It is bounded, 
 
 above by the soft palate and uvula, below by the root of 
 
 the tongue, and on either side by the arches of the palate, enclosing 
 
 the tonsils between them. 
 
 This movable prolongation of the roof of the mouth 
 is attached to the posterior border of the hard palate. 
 Inferiorly it is free, and from the middle hangs a pointed process 
 called the ' uvula.' It constitutes an imperfect partition between 
 the mouth and the posterior nares. Its upper or nasal surface is 
 convex and continuous with the floor of the nose ; its lower surface 
 is concave, in adaptation to the back of the tongue, and is marked 
 in the middle by a ridge, indicating its original formation by two 
 lateral halves. When the soft palate is at rest, it hangs obliquely 
 downwards and backwards ; but in swallowing, it is raised to the 
 horizontal position by the levatores palati, comes into apposition 
 
SOFT PALATE. 157 
 
 with the back of the pharynx, and thus prevents the food from 
 returning through the nose. 
 
 On making a perpendicular section through the soft palate, you 
 see that the great bulk of it is made up of mucous glands, which 
 lie thick on its under surface to lubricate the passage of the food. 
 Above these glands we come upon the aponeurosis of the palate, 
 still higher, upon the two portions of the palato-pharyngeus, 
 separated by the fibres of the levator palati, and, lastly, upon the 
 azygos uvulae covered by the nasal mucous membrane. The soft 
 palate is supplied with blood by the descendingpalatine branch of the 
 internal maxillary, and the ascending palatine branch of the ex- 
 ternal maxillary. Its nerves are derived from the palatine branches 
 of the second division of the fifth and from the glosso-pharyngeal. 
 The uvula projects from the middle of the soft palate, 
 
 and gives the free edge of it the appearance of a double 
 arch. It contains a number of mucous glands, and a small muscle, 
 the ' azygos uvulae.' Its length varies in different individuals, and 
 in the same person at different times, according to the state of its 
 muscle. It occasionally becomes permanently elongated, and 
 causes considerable irritation, a tickle in the throat, and harassing 
 cough. When you have to remove a portion of it, cut off only the 
 redundant mucous membrane. 
 
 The soft palate is continued into the tongue and 
 Arches o. the p} iarvnx by two folds of mucous membrane on each 
 
 side, enclosing muscular fibres. These are the anterior 
 and posterior half arches or pillars of the palate. The anterior 
 arch describes a curve from the base of the uvula to the side of the 
 tongue. It is well seen when the tongue is put out. The poste- 
 rior arch, commencing at the side of the uvula, curves along the 
 free margin of the palate, and terminates on the side of the 
 pharynx. The posterior arches, when the tongue is depressed, can 
 be seen through the span of the anterior. The pillars of each side 
 diverge from their origin, and in the triangular space thus formed 
 is situated the tonsil. The chief use of the arches of the palate is 
 to assist in the mechanism of deglutition. The anterior (enclosing 
 the ( palato-glossi ' muscles) contract so as to prevent the food 
 
158 SOFT PALATE. 
 
 from comiDg back into the mouth : the posterior (enclosing the 
 ' palato-pkaryngei') contract like side curtains, and co-operate in 
 preventing the food from passing into the nose. In vomiting, food 
 does sometimes escape through the nostrils, but one cannot wonder 
 at this, considering the violence with which it is driven into the 
 pharynx. 
 
 The muscles of the soft palate lie immediately under 
 Muscles of r J 
 
 the soft the mucous membrane. There are five pairs namely, 
 
 palate. j ie < i ev atores palati,' the ' circumflexi or tensores palati,' 
 
 the ' palato-glossi,' the ( palato-pharyngei,' and the 'azygos uvulae.' 
 This last pair is sometimes described as a single muscle. 
 
 This muscle arises from the apex of the petrous 
 portion of the temporal bone and from the cartilage of 
 the Eustachian tube. Its fibres spread out, and are 
 inserted along the upper surface of the soft palate, meeting those 
 of its fellow in the middle line (fig. 33). Its action is to raise the 
 soft palate, so as to make it horizontal in deglutition. 
 ' This muscle is situated between the internal ptery- 
 
 Circtimnextis l J 
 
 or tensor goid m. and the internal pterygoid plate of the sphenoid 
 palan. bone. It arises from the scaphoid fossa, and from the 
 
 outer side of the cartilage of the Eustachian tube. Thence it de- 
 scends perpendicularly, ends in a tendon which turns round the 
 hamular process, and expands into a broad aponeurosis, which is 
 inserted into the horizontal plate of the palate bone, and is also 
 connected to its fellow of the opposite side. It gives strength to 
 the soft palate. A synovial membrane facilitates the play of the 
 tendon round the hamular process. Its action is to draw down 
 and tighten the soft palate, and, owing to its insertion into the 
 palate bone, also to keep ,the Eustachian tube open. 
 Az os or This consists of two thin bundles of muscular fibres 
 
 levator situated one on each side of the middle line. They 
 
 arise from the aponeurosis of the palate and descend 
 along the uvula nearly down to its extremity. 
 Paiflfn crin< These muscles are contained within the arches of 
 
 x cllclLO'glOSSuS 
 
 and palato- the soft palate. The palato-glossus, within the an- 
 pharyngeus. ter j Qr arch ^ proceedg from tlie an t er ior surface of the 
 
TONSILS. 159 
 
 soft palate to the side of the tongue, and is lost in the st3^1o-glossus 
 muscle. The palato-pharyngeus, within the posterior arch, arises 
 from the posterior border of the soft palate by two origins separated 
 by the levator palati. It descends to the side of the pharynx, and 
 mixes with the fibres of the inferior constrictor and the stylo-pha- 
 ryngeus. 
 
 The tonsils are situated at the entrance of the fauces, 
 between the arches of the palate. Their use is to 
 lubricate the fauces during the passage of the food. On their 
 inner surface are visible from twelve to fifteen orifices leading into 
 depressions which give the tonsil an appearance like the shell of 
 an almond. Hence, as well as from their oval figure, they are 
 called the ' amygdalce? 
 
 These openings lead into small follicles in the substance of the 
 tonsil, lined by mucous membrane. Their walls are thick, and 
 formed by a layer of closed cells situated in the submucous tissue. 
 The cells secrete a glairy fluid, and closely resemble ' Peyers' ' 
 glands found in the intestines. The fluid, viscid and transparent, 
 in the healthy state, is apt to become white and opaque in in- 
 flammatory affections of the tonsils, and occasionally accumulates 
 in these superficial depressions, giving rise to the deceptive appear- 
 ance of a small ulcer, or even a slough in the part. 
 
 Concerning the relations of the tonsil, remember that it lies 
 close to the inner side of the internal carotid artery. It is only 
 separated from this vessel by the superior constrictor and the 
 aponeurosis of the pharynx. Therefore, in removing a portion of 
 the tonsil, or in opening an abscess near it, the point of the in- 
 strument should never be directed outwards, but imuards towards 
 the mesial line.* The tonsils are supplied with blood by the 
 tonsillar branch of the external maxillary, and the descending 
 palatine branch of the internal maxillary. 
 
 This canal conveys air from the pharynx to the 
 tympanum of the ear. Its orifice is situated opposite 
 the back part of the inferior spongy bone. The direc- 
 
 * Cases are related by Portal and Beclard, in which the carotid artery was punctured 
 in opening an abscess in the tonsil. The result was immediately fatal haemorrhage. 
 
160 EUSTACHIAN TUBE. 
 
 tion of the tube from the pharynx is upwards, backwards, and 
 outwards ; it is an inch and a half long. The narrowest part is 
 about the middle, and here its walls are in contact. Near the 
 tympanum its walls are osseous, but towards the pharynx they are 
 composed of fib ro- cartilage and fibrous membrane. The cartila- 
 ginous end projects between the origins of the levator and the 
 tensor palati, and gives attachment to some of their fibres. It is 
 situated at the base of the skull, in the furrow between the petrous 
 portion of the temporal and the great wing of the sphenoid bone. 
 It adheres closely to the bony furrow, as well as to the fibro- 
 cartilage filling up the ' foramen lacerum medium.' The orifice 
 is not trumpet-shaped, as usually described, but an elliptical slit 
 about half an inch long and nearly perpendicular. The fibro- 
 carfcilage bounds it only on the inner and the upper part of the 
 circumference ; the integrity of the canal externally is maintained 
 by tough fibrous membrane. 
 
 The Eustachian tube is lined by a continuation of the mucous 
 membrane of the pharynx, and covered by ciliated epithelium. 
 Hence, inflammatory affections of the throat or tonsils are liable 
 to be attended with deafness, from temporary obstruction of the 
 tube. 
 
 Mucous glands surround the orifice of the tube like a second 
 tonsil. They are similar in nature and function to the glands 
 beneath the mucous membrane of the mouth, the palate, and the 
 pharynx. 
 
 The hard- palate, formed by the superior maxillary and palate 
 bones, serves as a fulcrum for the tongue in the act of tasting, in 
 mastication, in deglutition, and in the articulation of sounds. The 
 tissue covering the bones is thick and close in texture, and firmly 
 united to the asperities on the bones. But it is not everywhere of 
 equal thickness. Along the raphe in the mesial line, it is much 
 thinner than at the sides ; for this reason, the hard palate is 
 in this situation more prone to be perforated by syphilitic disease. 
 
 A thick layer of glands (glandulce palatince) is arranged in 
 rows on either side of the hard palate. These glands become more 
 numerous and larger towards the soft palate. Their orifices are 
 
MECHANISM OF DEGLUTITION. 161 
 
 visible to the naked eye. The mucous membrane has a very 
 thick epithelial coat, which gives the white colour to the palate. 
 The descending palatine branch of the internal maxillary artery, 
 and the palatine nerves from the superior maxillary, may be traced 
 along each side of the roof of the mouth. The ramifications of 
 these arteries and nerves supply the soft as well as the hard 
 palate. 
 
 Mechanism With the anatomy of the parts fresh in your mind, 
 of degluti- consider for a moment the mechanism of deglutition. 
 lon ' The food duly masticated, is collected into a mass upon 
 
 the back of the tongue ; the lower jaw is then closed to give a fixed 
 point for the action of the muscles which raise the os-hyoides and 
 larynx, and the food is carried back into the pharynx by the 
 pressure of the tongue against the palate, at the same time that 
 the pharynx is elevated and expanded to receive it.* Having 
 reached the pharynx, the food is prevented from ascending into the 
 nasal passages by the approximation of the posterior palatine 
 arches, and the elevation of the soft palate, which thus forms a 
 horizontal temporary roof to the pharynx ; it is prevented from 
 returning into the mouth by the pressure of the retracted tongue, 
 and the contraction of the anterior palatine arches: it cannot enter 
 the larynx, because its upper opening is closed and protected by 
 the falling of the epiglottis : f consequently, being forcibly com- 
 pressed by the constrictors of the pharynx, the food passes into the 
 oesophagus. 
 
 The food passes with different degrees of rapidity through the 
 different parts of its course ; but most rapidly through the pharynx. 
 The necessity of this is obvious, when we reflect that the air-tube 
 must be closed while the food passes over it, and that the closure 
 produces a temporary interruption to respiration. The progress of 
 the food through the oesophagus is slow and gradual. 
 
 * The larynx being also elevated and drawn forward, a greater space is thus left 
 between it and the vertebrae for the distention of the pharynx. 
 
 f This falling of the epiglottis is effected, not by special muscular agency, but by 
 the simultaneous elevation of the larynx and the retraction of the tongue. A perpen- 
 dicular section through all the parts concerned is necessary to show the working of 
 this beautiful mechanism. 
 
 31 
 
162 DISSECTION OF THE LARYNX. 
 
 DISSECTION OF THE LARYNX. 
 
 Before commencing the dissection of the larynx, make yourself 
 familiar with the cartilages which compose it, and the ligaments 
 which connect them, as seen in a dry preparation. 
 
 This bone, named from its resemblance to the Greek 
 letter Upsilon, is situated between the larynx and the 
 tongue, and serves for the attachment of the muscles of the tongue. 
 It may be felt immediately below, and one inch and a half behind 
 the symphysis of the jaw. It is divided into a body, two greater 
 and two lesser cornua. The body is the thick central portion. 
 Its anterior surface is convex, and has a median vertical ridge ; 
 on each side of which are depressions for the attachment of muscles; 
 its posterior surface is smooth, concave, and corresponds to the 
 epiglottis. The greater cornua (right and left) project backwards 
 for about an inch and a half, with a slight inclination upwards, 
 and terminate in blunt ends tipped with cartilage. In young 
 subjects they are connected to the body of the bone by fibro- 
 cartilage; this in process of years becomes ossified. The lesser 
 cornua are connected, one on each side, to the point of junction 
 between the body and the greater cornua, by means of a little 
 joint lined by synovial membrane, which admits of free motion. 
 They are about the size of a barley-corn, and the stylo-hyoid 
 ligaments are attached to them. 
 
 The os-hyoides is connected to the thyroid cartilage by several 
 ligaments, which contain a quantity of elastic tissue. There is : 
 1. The thyro-hyoid membrane, which proceeds from the superior 
 border of the thyroid cartilage to the upper and posterior part of 
 the body of the hyoid bone. In front of this membrane there is, 
 in the perfect larynx, a bursa, of which the use is to facilitate the 
 play of the thyroid cartilage behind the os-hyoides. The central 
 portion is stronger than the lateral, hence it is sometimes called 
 the anterior thyro-hyoid ligament. Through the lateral part of 
 this membrane the superior laryngeal nerve and artery enter the 
 larynx. 2. The right and left lateral thyro-hyoid ligaments 
 
DISSECTION OF THE LARYNX. 163 
 
 extend between the extremities of the greater cornua of the os- 
 hyoides and the ascending cornua of the thyroid cartilage. They 
 often contain a little nodule of cartilage. 
 
 The frame-work of the larynx is composed of five 
 cartilages connected by joints and elastic ligaments, so 
 that they can be moved upon each other by appropriate 
 muscles ; the object of this motion being to act upon two elastic 
 ligaments called the ( vocal cords,' upon which the voice essentially 
 depends. 
 
 This cartilage, so called because it shields the beauti- 
 ^ mecoan i sm behind it,* consists of two lateral halves 
 (alee) united at an acute angle in front, which forms 
 the prominence termed * Pomum Adami? This prominence pre- 
 sents a notch at its upper part, to allow it to play behind the os- 
 hyoides in deglutition. There is a bursa in front of it. I have 
 seen this bursa as large as a pigeon's egg. The outer surface of 
 each ala is marked by an oblique line passing downwards and for- 
 wards from the upper cornu, which gives attachment to the 
 sterno-thyroid and thyro-hyoid muscles. The inferior border is 
 slightly arched in the middle, and on either side presents a convex 
 prominence, which gives attachment to the crico-thyroid muscle. 
 The superior border is nearly horizontal. The posterior border 
 is nearly vertical, and gives insertion to the stylo-pharyngeus and 
 palato-pharyngeus muscles. This border terminates above and 
 below in round projections called the upper and lower cornua. 
 The upper is the longer ; the lower articulates with the side of 
 the cricoid cartilage. 
 
 This cartilage, named from its resemblance to a 
 cartu!? e r ^ n g't ^ s situated below the thyroid. It is not of equal 
 depth all round. It is narrow in front, where it may be 
 felt about one quarter of an inch below the thyroid : from this 
 part, the upper border gradually rises, so that, posteriorly, the 
 ring is a full inch in vertical depth, and occupies part of the 
 interval left between the alse of the thyroid. In the middle of 
 
 , a shield. t KP'IKOS, a ring. 
 
 M 2 
 
164 DISSECTION OF THE LARYNX. 
 
 this broad posterior surface is a vertical ridge, on either side of 
 which observe a superficial excavation for the origin of the crico- 
 arytenoidei postici. On its upper part are two oval slightly convex 
 surfaces for the articulation of the arytenoid cartilages. In front, 
 its upper border presents a broad excavation to which the crico- 
 thyroid ligament is attached. On its lower border, external to 
 the depression for the crico-arytenoideus posticus, is an elevated 
 facet which articulates with the inferior cornu of the thyroid car- 
 tilage. The lower border is connected by elastic membrane to the 
 first ring of the trachea. 
 
 The thyroid is connected to the cricoid cartilage iri front by 
 the crico-thyroid membrane, which consists chiefly of elastic tissue, 
 and laterally by its two inferior horns. Between these two car- 
 tilages there is a perfect joint on either side, provided with a syno- 
 vial membrane, and secured by capsular ligaments. The object of 
 this joint is to permit the approximation of the cartilages. 
 
 These cartilages are situated, one on either side, at 
 tbe back of the cricoid - In tne recent state, before the 
 membranes and muscles have been removed, the space 
 between them resembles the lip of a ewer ; * hence their name. 
 Each is pyramidal with the apex upwards. The posterior surface 
 of each is concave, and gives attachment to the arytenoid muscle : 
 the anterior surface is convex and gives attachment to the thyro- 
 arytenoideus and the false vocal cord: the internal surface is 
 covered with mucous membrane and faces the corresponding sur- 
 face of the opposite cartilage : the base presents an oval surface, 
 which articulates with the cricoid cartilage. This joint has a very 
 loose capsular and synovial membrane, which permits motion in 
 all directions, like the first joint of the thumb. In front of the 
 base is a tubercle (anterior tubercle), which gives attachment to 
 the true vocal cord, and contributes to form part of the boundary 
 of the rima glottidis. At the outer and back part of the base is 
 another tubercle (external tubercle), into which certain muscles 
 moving the cartilage are inserted ; namely, the crico-arytenoideus 
 
 * 'A^trotj/a, a ewer. 
 
DISSECTION OF THE LARYNX. 165 
 
 posticus and crico-arytenoideus lateralis. The apex of the cartilage 
 is surmounted by one or two cartilaginous nodules, called ' corni- 
 cula laryngisS 
 
 This is a piece of yellow fibre-cartilage, which proiects 
 Epiglottis. ,. , ,., J . TJ. vi i r " i 
 
 over the larynx like a valve. It is like a leaf in shape, 
 
 with its stalk directed downwards. Its ordinary position is per- 
 pendicular, leaving the glottis free for respiration ; but during the 
 elevation of the larynx in deglutition it becomes horizontal, falls 
 over the glottis, and prevents the entrance of food into the larynx. 
 Understand that this falling of the epiglottis is accomplished, not 
 by special muscular agency, but by the simultaneous elevation of 
 the larynx and the retraction of the tongue. Its apex or lower 
 part is attached by the thyro-epiglottidean ligament to the angle 
 of the thyroid cartilage ; it is also connected by another ligament 
 (hyo-epiglottidean) to the os-hyoides. 
 
 The cartilages of the larynx resemble those of the ribs in struc- 
 ture. In the young they are dense and elastic, but they have a 
 tendency to ossify with age. In very old subjects, the thyroid and 
 cricoid cartilages are often completely ossified, and their interior 
 presents an areolar tissue, containing oily matter, analogous to the 
 spongy texture of the bones. The epiglottis is never ossified on 
 account of its peculiar organisation, which resembles that of the 
 ear and the nose. 
 
 The larynx is now to be examined in its perfect condition. 
 Mucous Except on the true vocal cords and the epiglottis, the 
 
 membrane of mucous membrane of the larynx presents a wrinkled 
 the larynx. a pp earancej and is loosely connected to the subjacent 
 structures by an abundance of fibre-cellular tissue, which admits 
 of its being pinched up into large folds. This tissue deserves 
 notice from the rapidity with which it becomes the seat of serous 
 effusion in acute inflammation of the larynx, and thus produces 
 sudden and alarming symptoms of suffocation. From the root of 
 the tongue to the anterior surface of the epiglottis, the membrane 
 forms three folds (glosso-epiglottidean), one median, and t\vo 
 lateral, containing elastic tissue. From the epiglottis it is con- 
 tinued backwards on either side to the apices of the arytenoid 
 
166 DISSECTION OF THE LARYNX. 
 
 cartilages, forming the < aryteno-epiglottidean ' folds which bound 
 the entrance into the larynx. In the natural state it is of a pale 
 rose colour, and covered by ciliated epithelium below the false 
 vocal cords, above these by squamous epithelium. 
 
 The mucous membrane of the larynx is remarkable for its acute 
 sensibility. This is requisite to guard the glottis during the 
 passage of the food over it. The glottis is closed during the act of 
 deglutition ; but, if during this process, any one attempt to speak 
 or laugh, the glottis opens, and allows the food to go, as it is 
 termed, the wrong way. As soon as the foreign body touches the 
 mucous membrane of the larynx, a spasmodic fit of coughing 
 expels it. 
 
 The sub-mucous tissue of the larynx is studded with mucous 
 glands. An oblong mass of them lies in the aryteno-epiglottidean 
 fold, and they are particularly numerous about the ( ventricles ' of 
 the larynx. The surface of the epiglottis towards the tongue is 
 abundantly provided with them. Their ducts pass through the 
 epiglottis, and may be recognised as minute openings on its laryn- 
 geal aspect. 
 
 Su erior This is the opening by which the larynx commnni- 
 
 opening of cates with the pharynx. Its outline is triangular, with 
 arynx. ^ g ^ SQ d{ rec ted forwards. Anteriorly it is bounded by 
 the epiglottis, laterally by the aryteno-epiglottidean folds, pos- 
 teriorly by the arytenoid cartilages. The apex presents the funnel- 
 shape appearance from which the arytenoid cartilages derive their 
 name. 
 
 Inferior Look down into the larynx and observe the trian- 
 
 opening of gular horizontal opening in the middle line ; this is the 
 or rima ' Tima glottidis,' or f glottis.' Its apex is directed 
 glottidis. forwards, its base backwards. The anterior two-thirds 
 of this opening is bounded by the inferior or true vocal cords, the 
 posterior third by the ar} T tenoid cartilages. Above the true vocal 
 cords are situated the superior or false vocal cords. On each side 
 of the larynx, between the true and false vocal cords, is a small 
 recess, the ventricle of the larynx, which leads into a pouch called 
 ' sacculus laryngis.' Pass the handle of the scalpel into one of 
 
DISSECTION OF THE LARYNX. 
 
 167 
 
 Cordse 
 vocales. 
 
 these cavities, and observe that it leads into a cul-de-sac, which 
 ascends for a short distance by the side of the thyroid cartilage. 
 These pouches contain a large number of muciparous glands. 
 The probable use of these cavities is to allow free space for the 
 vibration of the vocal cords. The mucous membrane lining them 
 is so sensitive that if a foreign body accidentally lodges there, the 
 patient has no rest until it is expelled. 
 
 These are the prominent folds which form the upper 
 fords 6 V Cal boun( iaries of the ventricles. They are called the < false 
 vocal cords ' because they have little or nothing to do 
 with the production of the voice. They are composed of elastic 
 tissue, like the true vocal cords ; but they also contain fatty tissue, 
 which the true ones do not. 
 
 These are two cords, composed of elastic tissue, ex- 
 tending horizontally from the angle of the thyroid 
 cartilage to the base of each of the arytenoid. They 
 diverge as they pass backwards ; the space between them is called 
 the f rima glottidis.' We shall presently see that, through the 
 muscles which act upon the ary- 
 tenoid cartilages, these cords can 
 be approximated or removed from 
 each other; in other words, the 
 rima glottidis can be closed or di- 
 lated. When sufficiently tight- 
 ened, and brought parallel by 
 means of certain muscles, the 
 cords are made to vibrate by the 
 stream of the expired air, and thus 
 is produced the voice. 
 
 What is the length of the true 
 
 vocal cords ? In the adult male they measure about five-eighths 
 of an inch ; in the female about four-eighths. In boys they are 
 shorter ; hence their peculiar voice. At puberty, the cords lengthen, 
 and the voice breaks. 
 
 The glottis admits of being dilated, contracted, and even com- 
 pletely closed by its appropriate muscles. When at rest, its shape 
 
 Fig. 34. 
 
 Thyroid cartilage. 
 True vocal cord. 
 
 Arytenoid cartilage. 
 Elastic ligament. 
 
 SHAPE OF THE GLOTTIS 
 WHEN AT REST. 
 
168 
 
 DISSECTION OF THE LARYNX. 
 
 is triangular, as shown in fig. 34, where the arytenoid cartilages are 
 cut through on a level with the vocal cords. During every in- 
 spiration, the glottis is dilated by the crico-arytenoidei postici ; it 
 then becomes spear-shaped (fig. 36). During expiration, it re- 
 sumes its triangular shape : and this return to a state of rest is 
 effected, not by muscular agency, but by two elastic ligaments 
 shown in fig. 34, which draw the arytenoid cartilages together. 
 Thus then the glottis, like the chest, is dilated by muscular 
 tissue ; like the chest, also, it is contracted by elastic tissue. In 
 
 Fig. 35. 
 
 Arytenoid cartilage . 
 Crico-arytenoid joint 
 
 Crico-thyroid joint . 
 
 Thyroid cartilage. 
 
 / - Thyroid cartilage depressed. 
 
 True vocal cord. 
 True vocal cord sti-etched. 
 
 Crico-thyroid muscle. 
 Cricoid cartilage. 
 
 DIAGEAM SHOWING THE ACTION OF THE CRICO-THYROID MUSCLE. 
 
 speaking or singing, the glottis assumes what is called the vocal- 
 ising position that is, the opening becomes narrower and its 
 edges nearly parallel. 
 
 j , . . There are nine muscles which act upon the ' rima 
 
 muscles of glottidis : ' four on each side and one in the middle. 
 the larynx, rpj^ f Qur p a ^ rg are ^ & cr i CO -thyroidei, the crico-aryte- 
 noidei postici, the crico-arytenoidei laterales, and the thyro-aryte- 
 noidei. The single one is the arytenoid eus. 
 
 This muscle is situated on the front of the larynx. 
 
 th' Widens Jt ar ^ ses from tue side of tne cricoid cartilage, ascends 
 
 obliquely outwards, and is inserted into the inferior 
 
DISSECTION OF THE LARYNX. 
 
 169 
 
 border of the thyroid. Its action is to tighten the vocal cords. 
 It does this by depressing the thyroid cartilage : for this cartilage 
 cannot be depressed without lengthening these cords, as shown 
 by the dotted line, fig. 35. Its nerve is the external laryngeal 
 branch of the superior laryngeal. 
 
 This muscle arises from the posterior part of the 
 
 M. crico- .... 
 
 arytenoideus cricoid cartilage : its fibres pass outwards and upwards, 
 posticus. an( j are inserted j n to the external tubercle of the ary- 
 tenoid. Its action is to dilate the glottis. It does this by drawing 
 the posterior tubercle of the arytenoid cartilage towards the 
 
 Fig. 36. 
 
 Vocal cord . . . 
 Thyroid cartilage 
 Cricoid- cartilage 
 
 Arytenoid cartilage 
 Elastic ligament (crico' 
 arytenoid) . . . , 
 
 Thy ro arytenoideus. 
 
 arytenoideus la- 
 teralis. 
 
 Ideal pivot. 
 
 Crico-arytenoideus pos- 
 ticus. 
 
 GLOTTIS DILATED. MUSCLES DILATING IT REPRESENTED WAVY. 
 
 mesial line, and therefore the anterior tubercle (to which the 
 vocal cord is attached) from the mesial line (fig. 36). In this 
 movement the arytenoid cartilage rotates as upon a pivot, and 
 acts as a lever of the first order ; the fulcrum or ideal pivot being 
 intermediate between the power and the weight. This muscle 
 dilates the glottis every time we inspire. Its nerve comes from 
 the inferior laryngeal. 
 
 This single muscle occupies the interval between the 
 
 noideiwT" ^ack of tbe arvtenoid cartilages. The fibres pass across 
 
 from one cartilage to the other. Most of them are 
 
 transverse, but some cross like the letter X, running from the 
 
170 
 
 DISSECTION OF THE LAKYNX. 
 
 base of the one to the apex of the other cartilage. Action. By 
 clasping the arytenoid cartilages, they assist in contracting the 
 glottis. 
 
 M crico- ^ ex P ose thi s muscle, cut away the ala of the 
 
 arytenoideus thyroid cartilage. It arises from the side of the 
 laterahs. cr i co id cartilage, and is inserted into the external tu- 
 bercle of the base of the arytenoid. Action. By drawing the 
 arytenoid cartilages inwards, the muscles of opposite sides contract 
 
 Fig. 37. 
 
 Vocal cord 
 
 Arytenoid cartilage 
 Elastic ligament . 
 
 Thyro-arytenoideus. 
 
 Crico-arytenoideus la- 
 teralis. 
 
 Crico-arytenoideus pos- 
 > ticus. 
 
 GLOTTIS CLOSED. MUSCLES CLOSING IT REPRESENTED WAVY. 
 
 the glottis (fig. 37). Its nerve comes from the inferior laryngeal. 
 M th ro- ^is mu scle arises from the angle of the thyroid 
 
 arytenoi- 
 deus. 
 
 cartilage and the crico-thyroid membrane, runs hori- 
 zontally backwards, and is inserted into the base and 
 anterior border of the arytenoid. Its fibres run parallel with the 
 vocal cord, and some of them are directly inserted into it. Part 
 of the muscle spreads out so as to form a floor for the ventricle of 
 the larynx, and is inserted into the outer border of the arytenoid 
 cartilage. Nerve from the inferior laryngeal. 
 
 This muscle relaxes the vocal cord. More than this, it puts 
 the lip of the glottis in the ' vocalising' position ; in this position, 
 the lips of the glottis are parallel, and the chink is reduced to the 
 breadth of a shilling.* 
 
 * M. aryteno-epiglottideus.This consists of a few pale muscular fibres enclosed in 
 the aryteno-epiglottidean fold. Some of them run near the free margin of the fold, 
 
DISSECTION OF THE LARYNX. 171 
 
 The following table shows the action of the several muscles which 
 act upon the glottis : 
 
 Crico-thyroidei . . . Stretch the Vocal Cords. 
 
 Thyro-arytenoidei . . Relax the Vocal Cords, and place them in the 
 
 vocalising position. 
 
 Crico-arytenoidei postici . Dilate the glottis. 
 Crico-arytenoidei laterales . Draw together the arytenoid \ 
 
 cartilages C ose the 
 
 Arytenoideus . . . Ditto Ditto Ditto J S lottls - 
 
 The blood-vessels of the larynx are derived from the superior 
 and inferior thyroid arteries. The laryngeal branch of the 
 superior thyroid passes through the thyro-hyoid membrane with 
 the corresponding nerve, and divides into branches, which supply 
 the muscles and the mucous membrane. The laryngeal branches 
 of the inferior thyroid ascend behind the cricoid cartilage. A 
 constant artery passes through the crico-thyroid membrane. 
 
 The nerves of the larynx are the superior and inferior (re- 
 current) laryngeal branches of the pneumogastric. 
 
 The superior laryngeal, having passed through the thyro-hyoid 
 membrane, divides into branches, distributed to the mucous mem- 
 brane of the larynx. Its filaments spread out in various direc- 
 tions ; some to the anterior and posterior surfaces of the epiglottis, 
 and to the aryteno-epiglottidean folds, others to the interior of the 
 larynx and the vocal cords. A constant filament descends behind 
 the ala of the thyroid cartilage, and communicates with the re- 
 current. Its external laryngeal branch supplies the crico-thyroid 
 muscle (p. 98). 
 
 The inferior (recurrent) laryngeal nerve enters the larynx 
 beneath the inferior constrictor, and ascends behind the joint 
 between the thyroid and cricoid cartilages. It supplies all the 
 intrinsic muscles of the larynx, except the crico-thyroid. If the 
 recurrent nerve be divided, or in any way injured, the muscles 
 
 others are found lower down. These, being distributed over the ventricle of the 
 larynx, can approximate its walls so as almost to obliterate the cavity. Hence the 
 name ' compressor sacculi laryngis,' given to this part of the muscle by Mr. Hilton 
 (Guy's Hospital Reports, vol. ii.), who first drew attention to it. 
 
172 DISSECTION OF THE TONGUE. 
 
 moving the glottis become paralysed, but its sensibility remains 
 unimpaired. When the nerve is compressed by a tumour for 
 instance, an aneurism of the arch of the aorta the voice is 
 changed to a whisper,* or even lost. 
 
 Until the approach of puberty, there is no great dif- 
 f erence m the relative size of the male and female 
 male and larynx. The male larynx, within two years after this 
 time, becomes nearly doubled in size ; the female grows 
 larger, but to a less extent. 
 The larynx of the adult male is in all proportions about one 
 third larger than that of the adult female. 
 
 The alse of the thyroid cartilage form a more acute angle in the 
 male ; hence the greater projection of the f pomum Adami,' and 
 the greater length of the vocal cords, in the male. 
 
 , (Male ... 8 lines. 
 The average length of the vocal cords is in the j -^ , 
 
 The average length of the glottis is in the . | Male ' ' ' 12 lines - 
 
 (Female . . 10 
 
 The size of the larynx does not necessarily follow the proportions 
 of the general stature ; it may be as large in a little person as in a 
 tall one : this corresponds with what we know of the voice. 
 Crico-th This joint is provided with a capsule and sy no vial 
 
 roid articu- membrane. There are, besides, two strong ligaments. 
 Both proceed from the cornu of the thyroid cartilage ; 
 the one upwards and backwards, the other downwards and forwards 
 to the cricoid. Eemember that the only kind of motion permitted 
 is vertical : and that this motion regulates the tension of the 
 vocal cords. 
 
 DISSECTION OF THE TONGUE. 
 
 The tongue is a complex muscular organ, subservient to taste, 
 speech, suction, mastication, and deglutition. It is connected by 
 muscles (genio-hyo-glossus, hyo-glossus, and stylo-glossus) to the 
 
 * Medical Gazette, Dec. 1843. 
 
DISSECTION OF THE TONGUE. 173 
 
 symphysis of the jaw, to the os-hyoides, and to the styloid process 
 of the temporal bone. To the soft palate it is connected by the 
 anterior palatine arch (p. 157) ; and to the epiglottis by three folds 
 of raucous membrane : in the middle fold is enclosed a layer of 
 elastic tissue, called the ' glosso-epiglottidean ' ligament. This 
 pulls up the epiglottis when the tongue is put out of the mouth : 
 hence the rule of never attempting to pass a tube into the oesopha- 
 gus without pushing back the tongue; otherwise the tube would 
 pass into the larynx. 
 
 The posterior part or root of the tongue is connected to the 
 hyoid bone by the hyo-glossi and the genio-hyo-glossi muscles ; its 
 anterior part or tip is free, and lies behind the lower incisor teeth. 
 Its upper surface or dorsum is convex with a median groove 
 which terminates posteriorly in a mucous follicle, the 'foramen 
 ccecam.^ On its under surface is a fold of mucous membrane, 
 called the '/rcenum lingucej which connects the tongue to the 
 floor of the mouth. 
 
 The surface of the tongue is covered with mucous membrane 
 which consists of structures similar to those of the skin generally ; 
 that is to say, it consists of a f cutis,' or true skin with numerous 
 projections, called 'papillce,' and of a thick layer of squamous 
 epithelium. The cutis is much thinner than that of the skin ; it 
 affords insertion to some of the superficial muscular fibres of the 
 tongue, and the blood-vessels form a close network in it before 
 they pass into the papillae. 
 
 The papillae on the tongue are distinguished, accord- 
 their s i ze an( i form* into three kinds, viz. 'papillce 
 maximce or circumvallatce,'' 'papillce fungiformcej 
 6 papillce filifoi^mce? (Fig. 38.) 
 
 The papillce circumvallatce vary in number from eight to 
 twelve. They are arranged at the back of the tongue in two 
 rows, which converge like the branches of the letter V, with the 
 apex backwards, towards the so-called ( foramen caecum.' Each of 
 these papillae is circular, from the ^-th to -j^-th of an inch wide, with 
 a central depression, and sorrounded by a fossa : the fossa itself 
 is circumscribed by an elevated ring. 
 
174 
 
 DISSECTION OF THE TONGUE. 
 
 The papillce fungiformce, smaller and more numerous than 
 the circumvallatw, are scattered chiefly over the sides and tip of 
 the tongue, and sparingly over its upper 
 surface. They vary in shape, some being 
 cylindrical, others having heads like mush- 
 rooms ; whence their name. Near the apex 
 of the tongue they may be distinguished 
 during life from the other papillae by their 
 redder colour. In scarlatina, and some ex- 
 anthematous fevers, these papillae become 
 elongated, and of a bright red colour : as the 
 fever subsides, their points acquire a brown- 
 ish tint ; giving rise to what is called ' the 
 strawberry tongue.' 
 
 The papillce filiformce are the smallest 
 and most numerous. They are so closely 
 aggregated that they give the tongue a velvet- 
 like appearance. Their points are directed 
 backwards, so that the tongue feels smooth, 
 if the finger be passed over it from apex to 
 base ; but rough, if in the contrary direction. 
 These papillae consist of small conical processes arranged for the 
 most part in a series of lines running parallel to the two rows of 
 the papillae circumvallatae. Each papilla is covered with a thick 
 layer of epithelium, which is prolonged into a number of free hair- 
 like processes. 
 
 If the papillae be injected, and examined under the microscope, 
 it is found that they are not simple elevations, like those of the 
 skin, but that from them arise secondary papillae. The ( papillae 
 circumvallatae ' consist of an aggregation of smaller papillae arranged 
 parallel to each other ; and the papillae fungiformae consist of cen- 
 tral stems from which minute secondary papillae shoot off. This 
 elaborate structure escapes observation because it is buried beneath 
 the epithelium.* Each secondary papilla receives a blood-vessel, 
 which passes nearly to its apex, and returns in a loop-like manner. 
 * See Bowman and Todd's ' Physiological Anatomy.' 
 
 1. Papillae circumvallatse. 
 
 2. Papillse fungiformse. 
 
DISSECTION OF THE TONGUE. 175 
 
 Filaments of the gustatory nerve have been traced in the papillae 
 circumvallatse and fungiformse, where they terminate in a minute 
 plexus. Their mode of termination in the papillse filiformse has 
 not been satisfactorily determined. 
 
 All the papillse are covered with a layer of squamous or tessel- 
 lated epithelium. That which covers the filiform is thicker than 
 the rest, and with a microscope is seen to project from their sides 
 like hair. The various kinds of ' fur ' on the tongue consist of 
 thickened and sodden epithelium. 
 
 Eespecting the use of the papillse, it is probable that they enable 
 the tongue to detect impressions with greater delicacy; and that 
 they are instrumental in detecting different kinds of sensation, 
 whether of taste or touch. From the density and arrangement of 
 their epithelial coat, the filiform papillae give the surface of the 
 tongue a roughness which is useful in its action upon the food. 
 An apparatus of this kind, proportionately stronger and more 
 developed, makes the tongue of ruminant animals an instrument 
 by which they lay hold of their food. In the feline tribe, e.g. the 
 lion and tiger, these papillse are so sharp and strong that they act 
 like rasps, and enable the animal to lick the periosteum from the 
 bones by a single stroke of his tongue. In some mammalia, they 
 act like combs for cleaning the skin and the hair. 
 
 Numerous small glands are found in the submucous tissue at the 
 root of the tongue. They are similar in structure and secretion to 
 the tonsillar and palatine glands, so that there is a complete ring 
 of glands round the isthmus faucium. Small round orifices upon 
 their surface indicate the termination of their ducts. Other 
 mucous glands, with ducts from one quarter to half an inch long, 
 are situated in the muscular substance of the tongue. 
 
 On the under surface of the apex of the tongue is 
 
 Glands be- , , . ., . , ,, , , 
 
 neath the placed, on either side, a group of glands presumed to be 
 apex of the salivary. Considering each group as one gland, observe 
 that it is oblong, with the long diameter from seven to 
 ten lines, parallel with the axis of the tongue. It lies near the 
 mesial line, a little below the ranine artery, on the outer side of 
 the branches of the gustatory nerve, under some of the fibres of 
 
176 DISSECTION OF THE TONGUE. 
 
 the stylo-glossus. Four or five ducts proceed from each group, and 
 terminate by separate orifices on the under surface of the tongue. 
 
 The interior of the tongue is composed of muscular 
 Muscular 
 fibres of the fibre and of a small quantity of fat. The extrinsic 
 
 tongue. muscles of the tongue have been described in the dis- 
 section of the submaxillary region (p. 41). We have now to exa- 
 mine its intrinsic muscles. For this purpose the mucous mem- 
 brane must be removed from the top of the tongue. On dissection 
 it will be found that the great bulk of the organ consists of fibres 
 which proceed in a longitudinal direction, constituting the ( lin- 
 guales' muscles. The lingualis of each half of the tongue is 
 separated into a superior and inferior layer by some transverse 
 fibres which pass nearly horizontally outwards from the 'fibrous 
 septum ' of the tongue. The superior fibres run in a longitudinal 
 direction under the mucous membrane of the dorsum, and are in- 
 serted into the submucous tissue. The ' inferior fibres ' (or ' true 
 lingualis^, more numerous than the preceding, are situated between 
 the genio-hyo-glossus and the hyo-glossus, and proceed from the 
 base to the apex of the tongue : these are readily exposed by dis- 
 secting on the under surface of the tongue immediately on the 
 outer surface of the genio-hyo-glossus. By the action of this mass 
 of longitudinal fibres the tongue can be moved so as to reach any 
 part of the mouth. Besides these longitudinal fibres, there are 
 transverse fibres which arise from the fibrous septum. These 
 pass outwards, running between the superior and inferior lingualis, 
 and are inserted into the sides of the tongue. A considerable 
 quantity of fat is found among these fibres. 
 
 If we trace the genio-hyo-glossi of opposite sides into the 
 tongue, we find that some of their fibres ascend directly to the 
 surface ; others cross each other in the middle line, intersect the 
 longitudinal fibres, and finally terminate upon the sides of the 
 tongue. Lastly, the fibres of the stylo-glossus should be traced 
 along the side of 'the tongue to the apex. 
 
 Fibrous ^ n *^ e mesial line, extending from the base to the 
 
 septum of apex of the tongue, is found a vertical plane of fibrous 
 the tongue. tissue? < ^ fibrous septum ; ' connected behind to the 
 
~ DISSECTION OF THE ORBIT. 1*7 
 
 body of the hyoid bone, and lost in front between the muscles. 
 " In it is sometimes found a piece of fibro-cartilage, called e nucleus 
 fibrosus linguae? a feeble representative of the lingual bone in 
 some of the lower animals. 
 
 The nerves supplying the tongue should be followed into its 
 substance. The hypoglossal nerve supplies all the muscles with 
 motor power. The gustatory or lingual branch of the fifth pair is 
 distributed to the mucous membrane about the apex and sides of 
 the tongue, and endows it with most acute sensibility. Upon this 
 nerve depends the sensation of all ordinary impressions, such as 
 that of hardness, softness, heat, cold, and the like. The glosso- 
 pharyngeal nerve supplies the mucous membrane at the back and 
 sides of the tongue. It is especially a nerve of taste. 
 
 DISSECTION OF THE OEBIT. 
 
 To expose the contents of the orbit, saw through the roof of the 
 orbit as far back as the optic foramen, making one section on the 
 outer side and the other on the inner side of the roof. In doing 
 this, be careful not to injure the little pulley on the inner side for 
 the superior oblique. The anterior fourth of the roof should be 
 left in situ, a the remainder removed by bone forceps. The eyeball 
 should be made tense by blowing air through a blow-pipe, passed 
 well into the globe through the end of the optic nerve. 
 
 The roof being removed, we expose the fibrous mem- 
 
 SfoSfeT of brane > which lines the walls of the orbit - Jt is a con - 
 
 tinuation of the dura mater through the sphenoidal 
 fissure. Traced forwards, we find that at the margin of the orbit 
 it divides into two layers, one of which is continuous with the 
 periosteum of the forehead, the other forms the broad tarsal liga- 
 ment which fixes the tarsal cartilage. 
 
 The fascia of the orbit serves the same purpose that 
 fascia does in other parts. It provides the lachrymal 
 gland, and each of the muscles, with a loose sheath, 
 thin and delicate at the back of the orbit, but stronger near the 
 eye. In this situation it passes from one rectus muscle to the 
 
 N 
 
178 
 
 DISSECTION OF THE ORBIT. 
 
 other, so that their tendinous insertions into the globe are connected 
 by it. From the insertion of the muscles it is reflected backwards 
 over the globe of the eye 3 and the optic nerve, and separates the 
 eye from the fat at the bottom of the orbit. 
 
 TV, , There are six muscles to move the eye ; four of 
 
 Muscles and 
 
 nerves of which, running in a straight direction, are called the 
 the orbit. 6 recti, and are arranged one above, one below, and 
 one on each side of the globe. The remaining two are called from 
 their direction, ' obliqui,' one superior, the other inferior. There 
 is also a muscle to raise the upper eyelid, termed ' levator palpebrce.' 
 
 Fig. 39. 
 
 DIAGRAM OF THE NERVES OF THE ORBIT. 
 
 The nerves are : the optic, which passes through the optic foramen ; 
 the third, the fourth, the first division of the fifth, and the sixth, 
 all of which pass through the sphenoidal fissure. The third 
 supplies all the muscles with motor power, except the superior 
 oblique, which is supplied by the fourth, and the external rectus, 
 which is supplied by the sixth. The ophthalmic division of the 
 fifth divides into a frontal, lachrymal, and nasal branch. The 
 orbit contains, also, a considerable quantity of soft fat, which forms 
 a bed for the eye and prevents it from being pulled too far back 
 by its muscles. Upon the quantity of this fat depends, in some 
 measure, the difference in the prominence of the eyes. Its absorp- 
 
DISSECTION OF THE ORBIT. 179 
 
 tion in disease or old age occasions the sinking of the eyes. The 
 eye is separated from the fat by a fold of the orbital fascia, which, 
 like a ( tunica vaginalis,' enables the globe to roll with the greatest 
 rapidity and precision. Lastly, the orbit contains the lachrymal 
 gland. 
 
 After the removal of the periosteum, and the fascia of the orbit, 
 the following objects are seen. In the middle we observe the 
 frontal nerve and artery, lying upon the levator palpebrse ; on the 
 inner side is the superior oblique muscle with its nerve (the 4th) ; 
 on the outer side is the lachrymal gland with the lachrymal nerve 
 and artery. 
 
 This is the largest of the three branches of the oph- 
 thalmic division of the fifth. It runs forwards upon 
 the upper surface of the levator palpebra, on which it 
 divides into two branches : 
 
 a. The supra-trochlear runs above the pulley of the superior 
 oblique to the inner angle of the orbit, and divides into branches, 
 which supply the skin of the upper eyelid, forehead, and ncse. 
 One or two very delicate filaments may be traced through the 
 bone to the mucous membrane of the frontal sinuses.* 
 
 b. The supra-orbital runs forwards to the supra-orbital notch, 
 through which it ascends. It supplies the skin of the upper eye- 
 lid, forehead, and scalp. 
 
 This is the smallest of the three divisions of the 
 
 P ntnalmic - Ifc runs alon g the outer side of the orbit 
 
 with the lachrymal artery, through the lachrymal gland, 
 and is distributed to the upper eyelid. Its branches within the 
 orbit are: 1, filaments to the lachrymal gland; 2, a malar, 
 which traverses a canal in the malar bone, and supplies the skin 
 of the cheek ; 3, one or two nerves, which pass down to commu- 
 nicate with the orbital branch of the superior maxillary division of 
 the fifth. 
 
 This nerve enters the orbit above the other nerves 
 
 Fourth, or 
 
 nervus which pass through the sphenoidal fissure. It runs 
 
 patheticus. a i on g f-.h e i nne r side of the frontal nerve, and enters 
 
 * These filaments have been noticed by Blumenbach, ' De Sinibus Frontal.' 
 
 N 2 
 
180 
 
 DISSECTION OF THE ORBIT. 
 
 Fig. 40. 
 
 the orbital surface of the superior oblique, to which it is exclusively 
 distributed. 
 
 This gland is situated within the external angular 
 Lachrymal p roce ss of the frontal bone. It is about the size and 
 shape of an almond. Its upper surface is convex, in 
 adaptation to the roof of the orbit ; its lower is concave, in adap- 
 tation to the eyeball. The anterior part of the gland lies some- 
 times detached from the rest, close to the back part of the upper 
 eyelid, and is covered by the conjunctiva. The whole gland is 
 kept in place by a capsule * formed by the fascia of the orbit. In 
 structure it resembles the salivary glands. 
 
 It consists of an aggregation of 
 small lobes composed of smaller 
 lobules, connected by fibre-cellular 
 tissue. The excretory ducts, seven 
 to ten in number, run parallel, and 
 perforate the conjunctiva about a 
 quarter of an inch above the edge of 
 the tarsal cartilage (fig. 40). They 
 are not easily discovered in the 
 human eye, but in that of the horse 
 or bullock they are large enough to 
 admit a small probe. The secretion 
 of the gland keeps the surface of the cornea constantly moist and 
 polished ; but if dust, or any foreign substance, irritate the eye, 
 the tears flow in abundance, and wash it off. 
 
 All the muscles of the orbit, with the exception of the inferior 
 oblique, arise from the margin of the foramen opticum, and pass 
 forwards, like ribands, to their insertions. 
 
 Levator This muscle arises from the roof of the orbit, im- 
 
 palpebrse mediately in front of the optic foramen. It gradually 
 ris * increases in breadth, and terminates in a broad, thin 
 aponeurosis, which is inserted into the upper surface of the tarsal 
 cartilage beneath the palpebral ligament. It is constantly in 
 
 * This capsule, being a little stronger on the under surface of the gland, is described 
 and figured by Scemmerring as a distinct ligament, ' Icones Oculi Humani,' tab. vii. 
 
DISSECTION OF THE ORBIT. 181 
 
 action when the eyes are open, in order to counteract the ten- 
 dency of the lids to fall. As sleep approaches, the muscle relaxes, 
 the eyes feel heavy, and the lids close. Its nerve comes from the 
 superior division of the third nerve, and enters it on its under 
 aspect. 
 
 This muscle arises from the inner side of the fora- 
 men opticum. It runs along the inner side of the 
 orbit, and terminates in a round tendon, which passes 
 through a cartilaginous pulley attached to the anterior and inner 
 part of the roof of the orbit. From this pulley the tendon is 
 reflected outwards and backwards to the globe of the eye. It 
 gradually expands, and is inserted into the outer and back part of 
 the sclerotica, between the external and superior recti. The 
 pulley is lined by a synovial membrane, which is continued upon 
 the tendon. The action of this muscle is to roll the eye on its own 
 axis. It is supplied by the fourth nerve, which enters the back 
 part of its upper surface. 
 
 The frontal nerve and levator palpebrse should now be reflected 
 from their middle, to expose the superior rectus muscle. 
 
 These four muscles have a tendinous origin round 
 muscles ^ e f ramen opticum, so that collectively they embrace 
 the optic nerve. They diverge from each other, one 
 above, one below, and one on either side of the optic nerve ; and 
 are named, accordingly, rectus superior, inferior, externus, and 
 interims. Their broad thin tendons are inserted into the opposite 
 sides of the sclerotic coat of the eye, about a quarter of an inch 
 from the margin of the cornea (fig. 41). 
 
 The external rectus not only arises from the circumference of 
 the optic foramen, but has another origin from the lower margin 
 of the sphenoid fissure. Between these origins pass the third nerve, 
 the nasal branch of the fifth, the sixth, and the ophthalmic vein. 
 The recti muscles enable us to direct the eye towards different 
 points ; hence the names given to them by Albinus attollens, 
 depressor, adductor, and abductor oculi. It is obvious that by 
 the single action of one, or the combined action of two, the eye 
 can be turned towards any direction. 
 
182 DISSECTION OF THE ORBIT. 
 
 The rectus superior is supplied by the upper division of the 
 third nerve ; the rectus internus, the rectus inferior and obliquus 
 inferior, by the lower division. The rectus externus is supplied by 
 the sixth. 
 
 Follow the recti to the eye, in order to see the tendons by which 
 they are inserted. Notice also the ' anterior ciliary arteries,' which 
 run to the eye along the tendons. The congestion of these little 
 
 vessels occasions the red zone round 
 the cornea in iritis. It has been 
 already mentioned that the tendons 
 are invested by a fascia, which 
 passes from one to the other, form- 
 ing a loose tunic over the back of 
 the eye. It is this fascia which 
 resists the passage of the hook in 
 the operation for the cure of 
 squinting. Even after the com- 
 plete division of the tendon, the 
 eye may still be held in its faulty 
 INSERTION OF THE RECTI MUSCLES WITH position, if this tissue, instead of 
 
 ANTERIOR CILIARY ARTERIES. 
 
 possessing its proper softness and 
 
 pliancy, happen to have become contracted and unyielding. 
 Under such circumstances it is necessary to divide it freely with 
 the scissors. 
 
 By removing the conjunctival coat of the eye, the tendons of 
 the recti are soon exposed. The breadth and the precise situation 
 of their insertion deserve attention in reference to the operation 
 for strabismus. The breadth of their insertion is about three 
 eighths of an inch, but, the line of this insertion is not at all 
 points equidistant from the cornea. The centre of the insertion 
 is nearer to the cornea by about one line than either end. Taking 
 the internal rectus, which has most frequently to be divided in 
 strabismus, we find that the centre of its tendon is, upon an 
 average, three lines only from the cornea, the lower part nearly 
 five lines, and the upper four. It is, therefore, very possible that 
 the lower part may be left undivided in the operation, being more 
 
DISSECTION OF THE ORBIT. 183 
 
 in the background than the rest. The tendon of the internal 
 rectus is nearer to the cornea than either of the others. 
 
 The superior rectus must now be reflected : in doing so, observe 
 the branch from the upper division of the third nerve, which 
 supplies it and the levator palpebrse. After the removal of a 
 quantity of fat, we expose the following objects: 1, the optic 
 nerve ; 2, the nasal nerve, the ophthalmic artery and vein, all of 
 which cross over the optic nerve from without inwards ; 3, the 
 inferior part of the third nerve ; 4, deeper towards the back of 
 the orbit, between the optic nerve and the external rectus, is 
 situated the * ophthalmic or lenticular ' ganglion ; and 5, the sixth 
 nerve entering the ocular aspect of the rectus externus. 
 
 Nasal nerve r ^ 1 * s * s one ^ ^ e ^ nree divisions f the ophthalmic 
 branch of the fifth pair (p. 178). It enters the orbit 
 through the sphenoidal fissure between the two origins of the 
 external rectus, and then crosses obliquely over the optic nerve 
 towards the inner wall of the orbit. After giving off the infra- 
 trochlear branch, the nerve runs out of the orbit between the 
 superior oblique and internal rectus, through the foramen orbi- 
 tale anterius, into the cranium, where it lies beneath the dura 
 mater, upon the cribriform plate of the ethmoid bone. However, 
 it soon leaves the cranium through a slit near the ' crista galli,' 
 and enters the nose. Here it sends filaments to the mucous 
 membrane of the upper part of the septum, and superior spongy 
 bone; but the main continuation of the nerve runs behind the 
 nasal bone, becomes superficial between the bone and the cartilage, 
 and, under the name of naso-lobular, is distributed to the skin of 
 the ala and tip of the nose. 
 
 The nasal nerve gives off the following branches in the orbit : 
 
 a. One or two slender filaments to the lenticular ganglion, 
 forming its upper or long root. 
 
 b. One or two long ciliary nerves. They run to the back of the 
 globe of the eye, and pass through the sclerotic coat to supply the 
 iris. 
 
 c. Infra-trochlear nerve. This runs below the pulley of the 
 superior oblique, where it communicates with the supra-trochlear 
 
184 DISSECTION OF THE ORBIT. 
 
 branch of the frontal nerve. It then divides into filaments, which 
 supply the skin of the eyelids, the lachrymal sac, and the side of 
 the nose. 
 
 Having passed through the optic foramen, this nerve 
 proceeds forwards and a little outwards to the globe of 
 the eye, which it enters on the nasal side of its axis. It then 
 expands to form the retina. The nerve is invested by a fibrous 
 coat derived from the dura mater. At the optic foramen it is sur- 
 rounded by the tendinous origins of the recti; in the rest of its 
 course, by loose fat and by the ciliary nerves and arteries. 
 
 This artery arises from the internal carotid. It 
 Ophthalmic en ^ ers the orbit through the optic foramen, outside the 
 
 artery. L 
 
 optic nerve ; occasionally through the sphenoidal fis- 
 sure. Its course is remarkably tortuous. Situated at first on the 
 outer side of the optic nerve, it soon crosses over it, and runs along 
 the inner side of the orbit, to inosculate with the internal angular 
 artery (the terminal branch of the facial). Its branches arise in 
 the following order : 
 
 a. Lachrymal artery. This branch proceeds along the outer 
 side of the orbit to the lachrymal gland. After supplying the 
 gland, it terminates in the upper eyelid. It anastomoses with the 
 deep temporal arteries, and also with a branch from the arteria 
 meningea media. 
 
 b. Supra-orbital artery. This branch runs forwards with the 
 frontal nerve along the roof of the orbit, and emerges on the fore- 
 head through the supra-orbital notch. 
 
 c. Arteria centralis retince. This small branch enters the 
 optic nerve, and runs in the centre of this nerve to the interior of 
 the eye. 
 
 d. Ciliary arteries, These branches proceed tortuously forwards 
 with the optic nerve. They vary from fifteen to twenty in number, 
 and perforate the sclerotic coat at the back of the eye, to supply 
 the choroid coat and the iris. They are sometimes called ' pos- 
 terior ciliary ,' to distinguish them from others named f anterior 
 ciliary' (branches of the muscular arteries), which proceed with 
 the tendons of the recti muscles, and enter the front part of the 
 
DISSECTION OF THE ORBIT. 185 
 
 sclerotica. In inflammation of the iris the vascular zone round the 
 cornea arises from enlargement and congestion of the anterior 
 ciliary arteries. 
 
 e, Ethmoidal arteries. These branches are two in number, the 
 anterior, the larger, passes through the anterior orbital foramen 
 with the nasal nerve ; the posterior enters the posterior orbital 
 foramen. Both give off anterior meningeal branches to the dura 
 mater, and also supply the mucous membrane of the nose. 
 
 /. Muscular arteries. These are uncertain in their origin, and 
 give off the anterior ciliary branches. 
 
 g. Palpebral arteries. These branches proceed from the lachry- 
 mal, nasal, and supra-orbital arteries. 
 
 h. Nasal artery. This branch may be considered one of the 
 terminal divisions of the ophthalmic. It leaves the orbit on the 
 nasal side of the eye, and inosculates with the angular artery (ter- 
 mination of the facial). It supplies the side of the nose and the 
 lachrymal sac. 
 
 i. Frontal artery. This is the other terminal branch of the 
 ophthalmic. It emerges at the inner angle of the eye, runs 
 upwards, and inosculates with the supra-orbital artery. 
 
 This commences at the inner angle of the eye, by a 
 Ophthalmic commun i C ation with the frontal and angular veins. It 
 
 vein. 
 
 runs backwards above the optic nerve in a straighter 
 course than the artery, receives corresponding branches, and finally 
 passes between the two origins of the external reetus, to terminate 
 in the cavernous sinus. 
 
 o v, h 1 ' ^i s little ganglion (G, p. 1 78), about the size of a pin's 
 or lenticular head, is situated at the back of the orbit, between the 
 ganglion. O ptic nerve and the external reetus. It receives a 
 sensitive branch (long root) from the nasal nerve, which joins its 
 posterior superior angle ; a motor branch (short root) from the 
 lower division of the third, which enters its posterior inferior angle ; 
 and it also receives (sympathetic) filaments from the plexus round 
 the internal carotid artery, which enter the ganglion between its 
 long and short roots. The ganglion thus furnished with motor, 
 sensitive, and sympathetic roots, gives off the ciliary nerves. 
 
186 DISSECTION OF THE ORBIT. 
 
 These, from ten to twelve in number, run forward very tortuously 
 with the optic nerve, pass through the back of the sclerotica, and 
 are distributed to the iris. Since the ciliary nerves derive their 
 motor influence from the third nerve, we see that the iris must 
 lose its power of motion when this nerve is paralysed. 
 
 Just before it enters the sphenoidal fissure, the third 
 m h toroculf' nerve divides into two branches, both of which pass 
 between the origins of the external rectus. The upper 
 division has been already traced into the superior rectus and levator 
 palpebrae. The lower division supplies a branch to the internal 
 rectus, another to the inferior rectus, and then runs along the 
 floor of the orbit to the inferior oblique muscle. 
 
 What is the result of paralysis of the third nerve ? falling of the 
 upper eyelid (ptosis), external squint, dilatation and immobility 
 of the pupil. 
 
 Sixth nerve nerve en ters the orbit between the origins of 
 
 motor ex- the external rectus, and terminates in fine filaments, 
 which are exclusively distributed to the ocular surface 
 of this muscle. 
 
 Eespecting the motor nerves in the orbit, observe that they all 
 enter the ocular surface of the muscles, with the exception of the 
 fourth. 
 
 Inferior ^is niuscle arises by a flat tendon from the superior 
 
 oblique maxillary bone, near the lower part of the lachrymal 
 muscle. groove. It runs outwards and backwards between the 
 rectus inferior and the orbit, then curves upwards between the 
 globe and the external rectus, and is inserted by a broad thin 
 tendon into the outer and back part of the sclerotic coat, close to 
 the tendon of the superior oblique. It is supplied by the lower 
 division of the third n. 
 
 The use of the oblique muscles is to rotate the eye 
 
 Action of ., ? . , , J , 
 
 the oblique upon its antero-posterior axis, so that, however much 
 JhTe 1 ? f tbe k eacl ^ e movecl obliquely to one side or the other, 
 the image of the object may be always kept stationary 
 upon one and the same point of the retina. This was first ex- 
 plained by Hunter. He says < When the head is moved towards 
 
SUPERIOR MAXILLARY NERVE. 187 
 
 the right shoulder, the superior oblique muscle of the right side 
 acts and keeps the right eye fixed on the object, and a similar 
 effect is produced upon the left eye by the action of its inferior 
 oblique muscle. When the head moves in a contrary direction, 
 the other oblique muscles produce the same effect.' * 
 
 This muscle has been particularly described by 
 
 Tensor tarsi. TT m 
 
 Horner,f an American anatomist. To expose it, cut 
 perpendicularly through the middle of the upper and lower lids, 
 and evert the inner halves towards the nose. After removing the 
 mucous membrane, the muscle will be seen arising from the ridge 
 on the lachrymal bone. It passes outwards and divides into two 
 portions, which are inserted into the upper and lower tarsal 
 cartilages, close to the orifices of the lachrymal ducts. It is 
 probable that the tensor tarsi draws backwards the open mouths 
 of the ducts, so that they may absorb the tears at the inner angle 
 of the eye. It is supplied by a small branch of the facial nerve. 
 Orbital This is always very small, and is sometimes absent, 
 
 branch of Jt comes from the trunk of the superior maxillary in 
 
 the supenor , , .,, ., . . 
 
 maxillary the spheno-maxiliary fossa (see diagram), enters the 
 nerve. orbit through the spheno-maxiliary fissure, and divides 
 
 into two branches. Of these, one, the temporal, after sending a 
 branch of communication to the lachrymal nerve in the orbit, 
 passes through a foramen in the malar bone to the temporal fossa. 
 It then pierces the temporal aponeurosis an inch above the 
 zygoma, and supplies the skin of the temple, joining the temporo- 
 auricular branch of the inferior maxillary. The other branch, the 
 malar ( ( subcutaneus mala?'), also passes through a foramen in 
 the malar bone, and supplies the skin of the cheek. 
 Superior To trace this nerve and its branches, we must remove 
 
 maxillary the outer wall of the orbit, so as to expose the spheno- 
 
 nerve, and .,, ,, 
 
 spheno-pala- maxillary fossa. 
 
 tine ganglion. The superior maxillary nerve is the second division 
 
 of the fifth cerebral nerve. Proceeding from the Grasserian gan- 
 
 * Observations on Certain Parts of the Animal Economy. 
 
 t Philadelphia Journal, Nov. 1824. But this muscle was accurately described by 
 Bosenmuller in his Handbuch der Anatomie. Leipzig, 1819. 
 
188 
 
 SUPERIOR MAXILLARY NERVE. 
 
 glion (fig. 42), it leaves the skull through the foramen rotundum, 
 passes horizontally forwards across the spheno-maxillary fossa, 
 enters the infra-orbital canal with the corresponding artery, and 
 finally emerges upon the face, through the infra-orbital foramen, 
 beneath the levator labii superioris. The branches given off are : 
 
 a. The orbital branch already described (p. 187). 
 
 6. Two branches to the spheno-palatine ganglion (MeckePs), 
 situated in the spheno-maxillary fossa. 
 
 c. Posterior dental branches, two or three. They descend along 
 the back part of the superior maxillary bone, and divide into 
 
 Fig. 42. 
 
 Trunk of the 
 fifth nerve . 
 
 Gasserian gan- 
 glion . . . 
 
 Facial n. 
 
 Chorda tym- 
 pani . . , 
 
 Submaxillary 
 ganglion . 
 
 Frontal, lachry- 
 mal and nasal 
 nn. 
 
 Orbital branch. 
 
 Infra-orbital n. 
 
 Anterior dental 
 
 n. 
 
 Naso-palatinen. 
 Palatine n. 
 
 Gustatory n. 
 
 DIAGRAM OF THE SUPERIOR MAXILLARY NERVE. 
 
 1. Spheno-palatine ganglion. 2. Otic ganglion. 
 
 smaller branches, which pass through holes in the bone in company 
 with minute arteries, and then run up the fangs of the molar teeth 
 to supply the pulp. They also supply the gums, and the lining 
 membrane of the antrum. 
 
 d. Anterior dental branch. This arises just before the nerve 
 emerges from the infra-orbital foramen. It descends in a special 
 canal in the anterior wall of the upper jaw, and gives filaments to 
 
SPHENO-PALATINE GANGLION. 189 
 
 the fangs of the first molar, canine, and incisor teeth. It also 
 supplies the gums and the mucous lining of the antrum. 
 
 6. The terminal branch, namely, the infra-orbital, was dissected 
 with the face (p. 82). 
 
 At this stage of the dissection, make a vertical incision rather on 
 one side of the middle line of the skull, to expose the cavity of 
 the nose. We shall thus be able to dissect the ' spheno-palatine 
 ganglion ' and its branches. 
 
 This little body (fig. 42), called, after its discoverer, 
 . ' Meckel's ganglion,' is deeply situated in the spheno- 
 maxillary fossa, close to the outer side of the spheno- 
 palatine foramen, immediately below the superior maxillary nerve. 
 Its sensitive roots proceed from the superior maxillary ; its motor 
 root from the vidian branch of the facial ; its sympathetic from the 
 carotid plexus, which joins the vidian nerve before it enters the 
 ganglion. Thus supplied, it furnishes branches to the mucous 
 membrane and glands of the hard and soft palate, and to the back 
 part of the nose. 
 
 Meckel's ganglion gives off the following branches : 
 
 a. Branches to the palate. To see these the mucous membrane 
 must be removed from the back part of the nose ; we shall then be 
 able to trace the nerves through their bony canals. Their course 
 is indicated by corresponding arteries. There are generally three 
 of these nerves, called by names originally given to them by 
 Meckel, anterior, middle, and posterior palatine. The anterior, 
 the large palatine nerve, descends through the posterior palatine 
 canal to the roof of the mouth, and then runs forwards along the 
 hard palate nearly to the gums of the incisor teeth ; but one or 
 two branches proceed backwards to supply the soft palate. The 
 middle palatine descends either in the same canal with the pre- 
 ceding, or in a smaller one of its own, and terminates exclusively 
 in the mucous membrane and glands of the soft palate. Thepos- 
 terior palatine nerve may be traced in a special bony canal down 
 to the soft palate, where it terminates in the mucous membrane 
 and glands. One or two filaments pass into the uvula.* 
 
 * According to Longet (Anat. et Physiol. du Systeme Nerveiix: Paris, 1842), the 
 posterior palatine nerve supplies the levator palati and the azygos uvulee with motor 
 
190 SPHENO-PALATINE GANGLION. 
 
 b. Spheno-palatine or nasal branches. These, three or four 
 in number, pass through the spheno-palatine foramen to the 
 mucous membrane of the nose. To see them clearly, the parts 
 should have been steeped for some time in dilute nitric acid : 
 afterwards, when well washed, these minute nerves may be easily 
 recognised beneath the mucous membrane covering the spongy 
 bones. Most of them ramify upon the outer wall of the nose and 
 the spongy bones. One branch (fig. 42), originally called by 
 Scarpa ( naso-palatine? traverses the roof of the nose, distributes 
 filaments to the back part of the septum narium, and then pro- 
 ceeds obliquely forwards along the septum to the foramen in- 
 cisivum, through which it passes, and finally terminates in the 
 palate behind the incisor teeth. 
 
 According to Cloquet, the corresponding nerves of opposite 
 sides unite at the foramen incisivum in a small ganglion which he 
 calls the 'naso-palatine.'* 
 
 c. Branches to the pharynx and Eustachian tube. In parts 
 prepared for the purpose we may sometimes trace minute fila- 
 ments to the mucous membrane of the back of the nares, the 
 Eustachian tube, and sphenoidal sinus. 
 
 d. Vidian branch. This proceeds, from the posterior part of 
 the ganglion, backwards through the vidian canal of the sphenoid 
 bone, traverses the fibro-cartilage at the base of the skull, and 
 here divides into two branches, fig. 43. One (the carotid) joins 
 the sympathetic plexus about the internal carotid artery ; the 
 other (sometimes called the great petrosal) enters the cranium, 
 runs under the Grasserian ganglion and the dura mater, in a small 
 groove on the petrous portion of the temporal bone, enters the 
 ' hiatus Fallopii,' and joins the facial nerve. It is probable that 
 the vidian nerve proceeds, not from, but to the ganglion, and that 
 
 power. In this view of the subject the nerve is considered to be the continuation or 
 terminal branch of the motor root of the ganglion, that, namely, derived from the 
 facial. This opinion is supported by cases in which the uvula is stated to have been 
 drawn on one side in consequence of paralysis of the opposite facial nerve. However, 
 we have not succeeded in tracing the nerve into these muscles. 
 
 * Dissert, sur les Odeurs et les Organes de 1'Olfaction : Paris, 1815. 
 
OTIC GANGLION. 191 
 
 it is the medium through which motor filaments are conveyed 
 to it. 
 
 The otic ganglion was discovered and described by 
 glfoiif an " Arnold, a German anatomist, in 1826.* ' It is situ- 
 ated,' he says, 'on the inner side of the inferior max- 
 illary division of the fifth pair, immediately below its exit through 
 the foramen ovale. (See diagram, page 188.) Its inner surface is 
 in contact with the circumflexus palati muscle and the cartilage 
 of the Eustachian tube, and immediately behind it is the middle 
 meningeal artery.' It is always of very small size. 
 
 Respecting its connections with other nerves, Arnold states that 
 the otic ganglion derives filaments (of sensation) from the inferior 
 maxillary, and also from the branch of this nerve, which goes to 
 the internal pterygoid muscle. It also derives a slender filament 
 from the temporo-auricular nerve. Its communication with the 
 sympathetic is established by filaments which proceed from the 
 ' nervi molles' round the middle meningeal artery. It communi- 
 cates also with the facial and glosso-pharyngeal nerves by a 
 branch commonly called the lesser petrosal nerve. This nerve 
 passes backwards either through the foramen ovale or the foramen 
 spinosum, or through a small hole between the two, and runs 
 beneath the dura mater along a minute groove on the petrous 
 bone (outside the great petrosal nerve). Here it divides into two 
 filaments, one of which joins the facial nerve in the aqueductus 
 Fallopii, the other joins the tympanic branch of the glosso-pharyn- 
 geal. These nerves are exceedingly difficult to trace, not only 
 on account of their minute size, but also because they frequently 
 run in canals in the petrous portion of the temporal bone. 
 
 The otic ganglion sends a branch to the tensor tympani and to 
 the circumflexus palati muscles. 
 
 * J. Arnold, Diss. inaug. med. &c. : Heidelbergse, 1826. 
 
192 DISSECTION OF EIGHTH PAIR OF NERVES OF SKULL. 
 
 DISSECTION OF THE EIGHTH PAIR OF NERVES AT THE BASE OF 
 
 THE SKULL. 
 
 In this dissection we propose to examine the glosso-pharyngeal, 
 pneumogastric, and spinal accessory nerves in the jugular fossa, 
 and the ganglia and nerves belonging to them in this part of their 
 
 Fig. 43. 
 
 DIAGRAM OF THE EIGHTH PAIB OF NERVES AT THE BASE OF THE SKULL. 
 
 1. Facial nerve. 10. Spheno-palatme or Meckel's ganglion. 
 
 2. Glosso-pharyngeal n. 11. Otic ganglion. 
 
 3. Pneumogastric. 12. Chorda tympani. 
 
 4. Spinal accessory. 13. Pharyngeal n. 
 
 5. Jacobson's or tympanic nerve. 14. Superior laryngeal n. 
 
 6. Lesser petrosal. 15. Jugular ganglion ) f , , . 
 
 7. Great petrosal branch, or Videan. . 16. Petrous ganglion ). 
 
 8. Branch to Eustachian tube. 17. Inferior ganglion 
 
 9. Arnold's or auricular n. 18. Superior ganglion 
 
 course. These are difficult to trace, and cannot be followed out 
 
 with success unless the nerves have been previously hardened by 
 
GANGLION OF ANDERSCH. 193 
 
 spirit, and the bones softened by acid. The first thing to be done 
 is to remove the outer wall of the jugular fossa. 
 
 This nerve passes through a separate tube of dura 
 
 mater in front f that f r the ther tw nerves ' L k - 
 
 ing at it from the interior of the skull, we observe that 
 it is situated immediately in front and rather to the inner side of 
 the jugular fossa. 
 
 In its passage through the fossa, the nerve presents two gan- 
 g] ionic enlargements, named respectively the jugular and the 
 petrous. 
 
 The jugular ganglion (ganglion superius) has been particularly 
 described by Muller."* It is found upon the nerve immediately 
 after its entrance into the canal of the dura mater, and is so 
 small that its size does not in any direction exceed -^th of an inch. 
 It occupies the outer side of the nerve, and does not implicate all 
 its fibres. According to our observation, this ganglion is fre- 
 quently absent. 
 
 The petrous ganglion (called, after its discoverer, the ganglion 
 of Andersch f ) is situated upon the glosso-pharyngeal nerve, near 
 the lower part of the jugular fossa. It is oval, and about -^-th of 
 an inch long. It is connected by filaments to the pneumogastric 
 and sympathetic nerves, and it gives off the tympanic or Jacob- 
 son's nerve. :f This tympanic branch of the glosso-pharyngeal 
 ascends through a minute canal in the bony ridge which separates 
 the carotid from the jugular fossa, to the inner wall of the tym- 
 panum, and terminates in several filaments. One traverses a 
 bony canal to the plexus of sympathetic nerves round the carotid 
 artery ; a second goes to the fenestra ovalis ; a third to the 
 fenestra rotunda ; a fourth is distributed to the mucous membrane 
 of the Eustachian tube ; a fifth ascends in front of the fenestra 
 ovalis, and joins the great petrosal nerve in the hiatus Fallopii ; a 
 sixth takes nearly a similar course, and under the name of the 
 lesser petrosal nerve proceeds along the front surface of the 
 
 * Medicin. Zeitung, Berlin, 1833, No. 52. 
 f Andersch, Fragm. descript. nerv. cardiac., 1791. 
 
 J This nerve, though commonly called Jacobson's, was fully described by Andersch. 
 
 O 
 
194 PORTIO DURA. 
 
 petrous bone to the otic ganglion. This tympanic branch is thus 
 distributed to the mucous membrane of the tympanum and the 
 Eustachian tube, and it communicates with the spheno -palatine 
 ganglion through the great petrosal nerve, and with the otic 
 ganglion through the lesser petrosal. 
 
 Pneumo- This nerve leaves the cranium with the nervus acces- 
 
 gastric sorius, through a canal in the dura mater behind that 
 
 for the glosso-pharyngeal. At its entrance into the 
 canal it is composed of a number of separate filaments ; but in 
 the foramen jugulare, these soon become imbedded in a small 
 ganglion the ganglion of the root of the pneumogastric. This 
 ganglion, first described by Arnold,* is about -j^th of an inch in 
 diameter. It is connected by filaments to the sympathetic, to the 
 petrous ganglion of the glosso-pharyngeal, to the spinal accessory 
 and the facial nerves. But its most singular branch is one named 
 by Arnold ' the auricular,' because it is distributed to the pinna 
 of the ear. This branch enters a minute foramen in the jugular 
 fossa, near the styloid process, and then proceeds through the 
 substance of the bone to the aqueductus Fallopii, where it 
 divides into two branches ; one joins the facial nerve, the other 
 passes to the outside of the head through a canal between the front 
 of the mastoid process and the meatus auditorius, and is distributed 
 to the cartilage of the ear, and the meatus auditorius. 
 
 Immediately below this its first ganglion the pneumogastric 
 nerve is joined by two branches from the nervus accessorius, and 
 consequently becomes after this junction a compound nerve. The 
 ganglion of the trunk, or inferior ganglion of this nerve below the 
 base of the skull, has been already examined (p. 97). 
 
 The portio dura or facial nerve, having arrived at 
 through the ^ ne bottom of the meatus auditorius internus, enters the 
 temporal ' aqueductus Fallopii.^ This is a tortuous canal ex- 
 cavated through the substance of the temporal bone, 
 and terminating at the stylo-mastoid foramen. When exposed 
 throughout its whole course, we observe that the nerve proceeds 
 
 * Der Kopftheil. des veget. Nerven Systems. Heidelberg, 1831. 
 
 f Fallopius was a distinguished Italian anatomist and professor at Paris, 1551. 
 
DISSECTION OF THE NOSE. 195 
 
 from the meatus interims for a short distance outwardly, then 
 makes a sudden bend backwards along the inner wall of the tym- 
 panum above the fenestra ovalis,'and, lastly, curving downwards at 
 the back of the tympanum, it leaves the skull at the stylo-mastoid 
 foramen. Its branches in the temporal bone are : 
 
 a. A communication between the facial and the auditory nerve 
 at the bottom of the meatus auditorius internus. 
 
 b. The great petrosal nerve (vidian), which runs to the spheno- 
 palatine ganglion (p. 192). 
 
 c. The lesser petrosal nerve, which runs to the otic ganglion. 
 
 d. Chorda tympani. This nerve arises from the facial about Jth 
 of an inch before its exit from the stylo-mastoid foramen, ascends 
 for a short distance in a bony canal at the back of the tympanum, 
 and enters that cavity below the pyramid and close to the mem- 
 brana tympani. It then runs forwards along the tympanum, across 
 the handle of the malleus, to the fissura Grlaseri, through which it 
 emerges at the base of the skull, and joining the gustatory nerve, 
 finally proceeds to the submaxillary ganglion, and ends in the 
 tongue. In its passage through the aqueductus Fallopii branches 
 are distributed to the stapedius and laxator tympani muscles. 
 
 DISSECTION OF THE NOSE. 
 
 Presuming that the dissector is familiar with the bones com- 
 posing the skeleton of the nose, we shall now describe, 1. The 
 nasal cartilages ; 2. The general figure and arrangement of the 
 nasal cavities ; 3. The membrane which lines them ; and, lastly, 
 the distribution of the olfactory nerves. 
 
 Two pieces of nbro-cartilage on either side assist in 
 forming the framework of the external nose ; and one 
 in the centre completes the septum between the nasal 
 fossae. 
 
 There are two lateral cartilages, an upper and a lower. The 
 upper, triangular in shape, is connected, superiorly, to the margin 
 of the nasal and superior maxillary bones, anteriorly, to the carti- 
 lage of the septum, and inferiorly, to the lower cartilage by means 
 
 o 2 
 
196 DISSECTION OF THE NOSE. 
 
 of a tough fibrous membrane. The lower is sometimes called the 
 cartilage of the pinna. It is elongated, and curved upon itself in 
 such a way as to form the boundary of the external opening of 
 the nose. Superiorly, it is connected by fibrous membrane to the 
 upper lateral cartilage ; internally it is in contact with its fellow 
 of the opposite side, forming the upper part of the ' columna 
 nasi ; ' posteriorly, it is attached by fibrous tissue to the superior 
 maxillary bone : in this tissue, at the base of the ala, are usually 
 found two or three nodules of cartilage, called ' cartilagines sesa- 
 moidece? By their elasticity they keep the nostrils continually 
 open, and restore them to their ordinary size whenever they have 
 been expanded by muscular action. 
 
 The cartilage of the septum, is placed perpendicularly in the 
 middle line : it may lean a little, however, to one side or the 
 other, and in some instances it is perforated, so that the two nasal 
 cavities communicate with each other. The cartilage is smooth 
 and flat, and its outline is nearly triangular. The posterior border 
 is received into a groove in the perpendicular plate of the eth- 
 moid ; the anterior border is much thicker than the rest of the 
 septum, and is connected, superiorly, with the nasal bones, and on 
 either side with the lateral cartilages. The inferior border is 
 attached to the vomer and the median ridge at the junction of the 
 palatine processes of the superior maxillae. 
 
 The muscles moving the nasal cartilages have been described 
 with the dissection of the face (p. 72). 
 
 A vertical section should be made through the right 
 
 Interior of nagal cav i ty a ii t tl e on the same side of the middle 
 the nose. J ' 
 
 line, to expose the partly bony and partly cartilaginous 
 
 partition of the nasal cavities (septum narium). Each nasal 
 fossa is narrower above than below. The greatest perpendicular 
 depth of each fossa is about the centre, and from this point the 
 depth gradually lessens, both towards the anterior and the pos- 
 terior openings of the nose. Laterally, each fossa is very narrow 
 in consequence of the projection of the spongy bones towards the 
 septum. : this narrowness in the transverse direction explains the 
 rapidity with which swelling of the lining membrane from a simple 
 cold obstructs the passage of air. 
 
DISSECTION OF THE NOSE. 197 
 
 The nasal fossae are bounded by the following bones : superi- \ 
 orly, by the nasal, the nasal spine of the frontal, the cribriform 
 plate of the ethmoid, and the body of the sphenoid ; inferiorly, 
 by the horizontal plates of the superior maxillary and palate bones ; 
 internally, is the smooth and flat septum formed by the perpen- 
 dicular plate of the ethmoid, the vomer, and the cartilage, also by 
 the nasal spine of the frontal, the rostrum of the sphenoid, and 
 the median ridge of the superior maxillary and palate bones; 
 externally, by the maxillary, the lachrymal, the ethmoid, the 
 palate, the inferior turbinated bone, and the internal pterygoid 
 plate of the sphenoid. 
 
 The outer wall of each nasal cavity is divided by the 
 turbinated bones into three compartments (meatus) of 
 unequal size ; and in these, are orifices leading to air- 
 cells (sinuses) in the sphenoid, ethmoid, frontal, and superior max- 
 illary bones. Each of these compartments should be separately 
 examined. 
 
 The superior meatus is the smallest of the three, and does not 
 extend beyond the posterior half of the wall of the nose. The 
 posterior ethmoidal and sphenoidal cells open into its anterior 
 part by one wide communication. 
 
 The middle meatus is larger than the superior. At its anterior 
 part is a long narrow passage (infundibulum), which leads up- 
 wards to the frontal and the anterior ethmoidal cells. About 
 the middle is a small opening which leads into the antrum of the 
 superior maxilla : this opening in the dry bone is large and ir- 
 regular, but in the recent state it is reduced nearly to the size of 
 a crow-quill by mucous membrane, so that a very little swelling 
 of the membrane is sufficient to close the orifice entirely. 
 
 Notice that the orifices of the frontal and ethmoid cells are so 
 disposed that their secretion will pass, by its own gravity, into the 
 nose. But this is not the case with the sphenoid and maxillary 
 cells; to empty which the head must be inclined on one side. 
 To see all these openings you must raise the respective turbinated 
 bones. 
 
 The inferior meatus extends nearly along the whole length of 
 
198 DISSECTION OF THE NOSE. 
 
 the outer wall of the nose. By raising the lower turbinated bone, 
 we observe, towards the front of the meatus, the termination of 
 the nasal duct, through which the tears pass down from the 
 lachrymal sac into the nose. This sac and duct we can now con- 
 veniently examine. 
 
 Lach al ^is * s ^ e P assa e e through which the tears are 
 sac and conveyed from the lachrymal ducts into the nose (p. 70). 
 ac ' The lachrymal sac occupies the groove on the nasal 
 side of the orbit, formed by the lachrymal and superior maxillary 
 bones. The upper end is round and closed ; the lower gradually 
 contracts into the nasal duct, and opens into the inferior meatus, 
 The sac is composed of a strong fibrous membrane, which adheres 
 very closely to the bone, and is lined by mucous membrane. Its 
 front surface is covered by the tendo oculi and the fascia proceed- 
 ing from it. 
 
 The nasal duct is from half to three quarters of an inch in 
 length, and is directed downwards and backwards. Its termina- 
 tion is guarded by a valvular fold of mucous membrane ; conse- 
 quently, when air is blown into the nasal passages while the 
 nostrils are closed, the lachrymal sac does not become distended. 
 The lachrymal sac and the nasal duct are lined with ciliated epi- 
 thelium and the canaliculi with the squamous variety. 
 
 Behind the inferior turbinated bone is the opening of the 
 Eustachian tube (p. 159). Into this, as well as into the nasal duct, 
 we ought to practice the introduction of a probe. The chief diffi- 
 culty is to prevent the probe from slipping into the cul-de-sac 
 between the tube and the back of the pharynx. 
 
 Mucous or membrane lines the cavities of the nose and 
 
 Schneiderian the air-cells communicating with it, and adheres very 
 membrane.* fi rm ]y t o ^ e periosteum. Its continuity may be traced 
 into the pharynx, the various sinuses, the orbits through the 
 nasal ducts, and into the tympana and mastoid cells through the 
 Eustachian tubes. Observe that at the lower border of the turbi- 
 nated bones it is disposed in thick and loose folds. The mem- 
 brane varies in thickness and vascularity in different parts of the 
 
 * Schneider, De catarrhis. Wittenberg, 1660. 
 
DISSECTION OF THE NOSE. 199 
 
 nasal cavities. Upon the lower half of the septum, and the lower 
 turbinated bones it is much thicker than elsewhere, in consequence 
 of a minute plexus of arteries and veins in the submucous tissue. 
 In the sinuses, the mucous membrane is thinner, less vascular, and 
 closely applied upon the periosteum. 
 
 The great vascularity of the Schneiderian membrane is obviously 
 intended to elevate the temperature of the inspired air, and to 
 pour out a copious secretion which prevents the membrane from 
 becoming too dry. 
 
 Near the nostrils the mucous membrane is furnished with 
 papillae, a squamous epithelium, like the skin, and a few small 
 hairs (vibrissce). In the sinuses and all the lower regions of the 
 nose, the epithelium is columnar, and provided with cilia ; but in 
 the upper part of the nose, where the sense of smell resides, we no 
 longer find ciliated epithelium, but columnar ; beneath which is a 
 stratum of nucleated cells.* 
 
 Bloodvessels Tlie arteries f ^ e nose are ? tlie ethmoidal and 
 of the interior nasal branches of the ophthalmic, and the nasal branch 
 of the nose. Q f ^ j n t erna | maxillary, which enters the nose 
 through the spheno-palatine foramen. The external nose is 
 supplied by the arteria lateralis nasi. 
 
 The veins of the nose correspond to the arteries. They com- 
 municate with the veins within the cranium through foramina in 
 the cribriform plate of the ethmoid bone, also through the oph- 
 thalmic vein and the cavernous sinus. These communications 
 explain the relief afforded by haemorrhage from the nose in cases 
 of cerebral congestion. 
 
 The olfactory nerves, proceeding from each olfactory 
 
 nerves ry bulb, in number about twenty on either side, pass 
 
 through the foramina in the cribriform plate of the 
 
 ethmoid bone. In its passage each nerve is invested with a coat 
 
 derived from the dura mater. They are divided into an inner, 
 
 a middle, and an outer set. The inner traverse the grooves on 
 
 the upper third of the septum. The middle supply the roof of 
 
 the nose. The outer pass through grooves in the upper and 
 
 * Bowman and Todd's Physiolog. Anatora., cap. xvi. 
 
200 MUSCLES OF THE BACK. 
 
 middle turbinated bones, and are lost in the mucous membrane on 
 the convex surfaces of these bones.* 
 
 The olfactory nerves descend between the mucous membrane and 
 the periosteum, and break up into filaments which communicate 
 freely with one another and form minute plexuses. Owing to the 
 difficulty of tracing the ultimate filaments, the exact mode of termina- 
 tion is at present undetermined. Microscopically, the olfactory fila- 
 ments differ from the other cerebral nerves, in containing no white 
 substance of Schwann, and in being finely granular and nucleated. 
 
 The olfactory are nerves of special sense. The common sensi- 
 bility of the mucous membrane of the nose is supplied by branches 
 from the fifth pair of nerves ; namely, the nasal branch of the 
 ophthalmic (p. 178), the nasal branch of the spheno-palatine 
 ganglion (p. 190), and the Vidian nerve. That the sense of smell 
 is independent of the common sensibility of the nose is proved by 
 experiment and by pathology. For instance, any disease affecting 
 the olfactory nerve, even the inflammation of a common cold, im- 
 pairs the sense of smell, whereas the common sensation of the part 
 continues equally acute, and becomes even more so, as one may 
 readily ascertain by introducing a foreign body into the nostril. 
 
 DISSECTION OF THE MUSCLES OF THE BACK. 
 
 Those muscles of the back, namely, the trapezius, latissimus 
 dorsi, levator anguli scapulae, and rhomboidei, which are concerned 
 in the movements of the upper extremity, will be examined in the 
 dissection of the arm. These, therefore, having been removed, we 
 proceed to examine two muscles, named, from their appearance, 
 'serrati, 9 which extend from the spine to the ribs. 
 Serratus ^ n * s musc ^ e ^ s situated beneath the rhomboidei. It 
 
 posticus arises from the ligamentum nucha3,f the spines of the 
 last cervical, and two or three upper dorsal vertebras, by 
 
 * See the plates of Scarpa and Soemmerring. 
 
 t The ligamentum nuchse is a rudiment of the great elastic ligament of quadrupeds 
 (termed the pack-wax] which supports the weight of the head. It proceeds from the 
 spine of the occiput to the spines of all the cervical vertebrae except the atlas ; other- 
 wise it would interfere with the free rotation of the head. 
 
Vertebral 
 
 MUSCLES OF THE BACK. 201 
 
 a sheet-like aponeurosis which makes up nearly half the muscle : 
 the fibres run obliquely downwards and outwards, and are inserted 
 by fleshy slips into the second, third, fourth, and sometimes the 
 fifth ribs beyond their angles. Its action is to raise these ribs, 
 and therefore to assist in inspiration. 
 
 This muscle is situated beneath the latissimus dorsi. 
 
 oerratus . *, 
 
 posticus It amses from the strong aponeurosis called ' vertebral 
 inferior. apoueurosisj opposite the two last dorsal and two 
 upper lumbar vertebrae. It ascends obliquely outwards, and is 
 inserted by fleshy slips into the four lower ribs, external to their 
 angles. The tendency of its action is to pull down these ribs, and 
 therefore to assist in expiration. 
 
 The dense and shining aponeurosis which covers the 
 erector spinae is called ' vertebral aponeurosis.' It is 
 
 aponeurosis. * 
 
 attached to the crest of the ilium, to the spines of the 
 lower dorsal, all the lumbar, and sacral vertebrae. Its use is, not 
 only to form a sheath for the erector spinae, but to give origin to 
 the latissimus dorsi, the serratus posticus inferior, the internal 
 oblique and transverse muscles of the abdomen. If you make a 
 vertical incision through it and reflect it, you will see that on the 
 outer side of the erector spinae it is inseparably connected with 
 the tendinous attachments of the internal oblique and transversalis 
 to the transverse processes of the lumbar vertebras. 
 
 The serratus posticus superior must now be reflected from its 
 origin, and turned outwards to expose the following muscle. 
 
 This arises from the spines of the five or six upper 
 
 LUS> dorsal and the last cervical vertebra, and from the 
 
 lower half of the ligamentum nuchae. The fibres ascend and divide 
 
 into two portions, named, according to their respective insertions, 
 
 splenius capitis and splenius colli. 
 
 a. The splenius capitis is inserted into the mastoid process, and 
 the superior curved ridge of the occipital bone beneath the sterno- 
 mastoid. 
 
 6. The splenius colli is inserted by tendinous slips into the 
 posterior tubercles of the transverse processes of the three upper 
 cervical vertebrae. 
 
202 MUSCLES OF THE BACK. 
 
 The action of the splenius, taken as a whole, is to draw the head 
 and the upper cervical vertebrae towards its own side: so far, it 
 co-operates with the opposite sterno-mastoid muscle. When the 
 splenii of opposite sides contract, they extend the cervical portion 
 of the spine, and keep the head erect. The permanent contraction 
 of a single splenius may occasion ' wry neck.' It is necessary to 
 be aware of this, otherwise one might suppose the opposite sterno- 
 mastoid to be affected, considering that the appearance of the 
 distortion is alike in either case. 
 
 The splenius and serratus posticus inferior are to be detached 
 from their origins ; after reflecting the vertebral aponeurosis from, 
 its internal attachment the erector spinae is exposed. 
 
 The mass of muscle which occupies the vertebral 
 Erector groove on either side of the spine, is, collectively, called 
 ' erector spinse,' since it counteracts the tendency of the 
 trunk to fall forwards. Observe that it is thickest and strongest 
 at that part of the spine where it has the greatest weight to support, 
 namely, in the lumbar region ; and that its thickness gradually 
 decreases towards the top of the spine. 
 
 It arises by tendinous fibres- from the posterior fifth of the crest 
 of the ilium, the sacrum, and the spines of the lumbar vertebras. 
 From this extensive origin the muscular fibres ascend, at first as a 
 single mass. Near the last rib, this mass divides into two ; an 
 outer, called the f sacro-lumbalis ; ' an inner, the ' longissimus 
 dorsi? These two portions should be followed up the back : and 
 there is no difficulty in doing so, because the division is indicated 
 by a longitudinal groove, in which we observe the cutaneous branches 
 of the intercostal vessels and nerves. 
 
 Tracing the sacro-lumbalis upwards, we find that it 
 balis" 1Um " terminates in a series of tendons which are inserted into 
 the angles of the six lower ribs. 
 
 By turning outwards the sacro-lumbalis, we observe 
 Musculus j s con tinued upwards under the name of ' mus- 
 
 accessorius. 
 
 culus accessorius ad sacro-lumbalem.' This arises by 
 a series of tendons from the angles of the seven or eight lower ribs, 
 and is inserted into the angles of the five or six upper ribs. 
 
MUSCLES OF THE BACK. 203 
 
 This is the cervical continuation of the musculus 
 accessorius. It arises by tendinous slips from the four 
 or five upper ribs, and is inserted into the transverse 
 processes of the three or four cervical vertebrae. 
 
 The longissimus dorsi (the inner portion of the erector 
 s pi n *) terminates in tendons which are inserted into the 
 tubercles * at the root of the transverse processes of the 
 lumbar vertebrae, also into the transverse processes of all the 
 dorsal vertebras, and into the greater number of the ribs (varying 
 from eight to eleven) close to their junction with the transverse 
 processes. 
 
 This is the cervical continuation of the longissimus 
 dorsi. It arises by tendinous- slips from the transverse 
 processes of the second, third, fourth, fifth, and sixth 
 dorsal vertebrae, and is inserted into^the posterior tubercles of the 
 transverse processes of the four or five lower cervical vertebrae. 
 
 This muscle, situated on the inner side of the pre- 
 mtoid~ ceding, is the continuation of the trans versalis colli to 
 the cranium. It arises from the transverse processes 
 of the fourth, fifth, and sixth dorsal, and the articular processes of 
 the three or four lower cervical vertebrae, and is inserted by a flat 
 tendon into the back part of the mastoid process beneath the 
 splenius.f 
 
 * Called ' anapophyses ' by Professor Owen. 
 
 f Those who are familiar with the transcendental nomenclature of the vertebrate 
 skeleton, will understand, from the following quotation, the plan upon which the 
 muscles of the back are arranged : 
 
 ' The muscles of the back are either longitudinal or oblique ; that is, they either 
 pass vertically downwards from spinous process to spinous process, from diapophysis 
 to diapophysis, from rib to rib (pleurapophyses), &c., or they extend obliquely from 
 diapophysis to spine, or from diapophysis to pleurapophysis, &c. 
 
 ' The erector spinse is composed of two planes of longitudinal fibres aggregated 
 together, below, to form one mass at their point of origin, from the spines and pos- 
 terior surface of the sacrum, from the sacro-iliac ligament, and from the posterior 
 third of the iliac crest. It divides into two portions, the sacro-lumbalis and the 
 longissimus dorsi. 
 
 1 The former, arising from the iliac crest, or from the pleurapophysis (rib) of the 
 first sacral vertebra, is inserted by short flat tendons into (1.) the apices of the stunted 
 lumbar ribs, close to the tendinous origins of the transversalis abdominis ; (2.) the 
 
204 
 
 MUSCLES OF THE BACK. 
 
 This is a long narrow muscle, situated close to the 
 spines of the dorsal vertebrae, and apparently a part of 
 the longissimus dorsi. It arises by tendinous slips 
 from the spines of the two lower dorsal and two upper lumbar 
 vertebrae, and is inserted by little tendons into the spines of the 
 six or eight upper dorsal vertebrae. 
 
 The muscles of the spine hitherto examined are all longitudinal 
 in their direction. ^e now come to a series which run obliquely 
 from the transverse to the spinous processes of the vertebrae. And 
 first of the complexus. 
 
 This powerful muscle arises from the transverse pro- 
 cesses of the three or four upper dorsal and the last 
 cervical vertebrae, also from the articular processes of the fourth, 
 fifth, and sixth cervical vertebrae. It is inserted between the two 
 curved lines of the occiput, near the vertical crest. In the centre 
 of the muscle there is generally tendinous tissue.* The muscle is 
 perforated by the posterior branches of the second (the great occi- 
 pital), third, and fourth cervical nerves. Its action is to maintain 
 the head erect. 
 
 Cut transversely through the middle of the complexus, and 
 
 angles of the eight or nine inferior dorsal ribs ; (3.) it is inserted, through the medium 
 of the musculus accessorius, into the angles of the remaining superior ribs, and into 
 the long and occasionally distinct pleurapophysial element of the seventh cervical 
 vertebra; and (4.) through the medium of the cervicalis ascendens, into the pleura- 
 pophysial elements of the third, fourth, fifth, and sixth cervical vertebrae. In other 
 words, the muscular fibres extend from rib to rib, from the sacrum to the third cervical 
 vertebra. 
 
 ' The longissimus dorsi, situated nearer the spine than the sacro-lumbalis, is in- 
 serted (1.) into the metapophysial spine of the lumbar diapophyses; (2.) into the 
 diapophyses of all the dorsal vertebrae, near the origin of the levatores costarum ; 
 (3.) through the medium of the transversalis colli into the diapophyses of the second, 
 third, fourth, fifth, and sixth cervical vertebrae ; and (4.) through the medium of the 
 trachelo-mastoid into the mastoid process, or the only element of a transverse process 
 possessed by the parietal vertebra. In other words, its fibres extend from diapophysis 
 to diapophysis, from the sacrum, upwards, to the parietal vertebra.' Homologies of 
 the Human Skeleton, by H. Coote, p. 75. 
 
 * The inner border of the complexus is described by some anatomists as a separate 
 muscle, under the name of ' biventer cervicis,' simply because it consists of two 
 muscular portions united by an intermediate tendon. 
 
MUSCLES OF THE BACK. 205 
 
 reflect it to see the 'arteria cervicalis profunda ' (p. 60), and the 
 posterior branches of the cervical nerves. 
 
 This is the mass of muscle which lies in the vertebral 
 g roove after fcne reflection of the complexus and the 
 erector spinse. It consists of a series of fibres which 
 extend from the transverse and articular processes to the spinous 
 processes of the dorsal and cervical vertebra?, and is usually divided 
 into the * aemispinalis dorsi ' and ' semispinalis colli.' 
 
 a. The semispinalis dorsi arises from the transverse processes 
 of the dorsal vertebra?, from the sixth to the tenth, and is inserted 
 into the spines of the four upper dorsal and the two or three lower 
 cervical vertebras. 
 
 b. The semispinalis colli arises from the transverse processes of 
 the five or six upper dorsal vertebra?, and the articular processes of 
 the four lower cervical, and is inserted into the spines of the axis 
 and the three or four succeeding vertebra?. 
 
 Now reflect part of the semispinalis dorsi in order to expose the 
 'multifidus spineeS This may be considered a part of the pre- 
 ceding muscle, since its fixed points and the direction of its fibres 
 are the same. It consists of a series of little muscles which extend 
 between the spines and transverse processes of the vertebra? from 
 the sacrum to the second cervical vertebra. Those in the lumbar 
 region are the largest. They arise by tendinous slips from the 
 transverse processes in the sacral and dorsal region, and from the 
 articular processes in the lumbar and cervical region. They all 
 ascend obliquely, and are inserted into the spines and lamina? of all 
 the vertebra? excepting the atlas. It should be observed that their 
 fibres are ifSbt of uniform length ; some extend only from vertebra 
 to vertebra, while others extend between one, two, or even three 
 vertebra?.* 
 
 The action of these oblique muscles is not only to assist in 
 
 * Beneath the multifidus spinse we find, in the dorsal region of the spine only, 
 eleven little flat muscles, called by Theile (Miiller's Archives f. Anat. &e., 1839), who 
 first described them, ' rotatores spines! They arise from the upper part of the trans- 
 verse process, and are inserted into the lower border of the lamina of the vertebra 
 above. These muscles form but a part of the multifidus spinae. 
 
206 MUSCLES OF THE BACK. 
 
 maintaiaing the trunk erect, but to bend the spine to one or the 
 other side. 
 
 These little muscles arise from the apices of the 
 transverse processes of the dorsal vertebrae, and are 
 inserted into the rib below. The direction of their 
 fibres corresponds with tbat of the outer layer of the intercostal 
 muscles. They are muscles of inspiration. 
 
 The muscles extend between the spines of contiguous 
 vertebras. They are arranged in pairs, and only exist 
 in those parts of the vertebral column which are the most mov- 
 able. In the cervical region they pass between the spines of the 
 six lower cervical vertebrae. In the dorsal they are found between 
 the spines of the first and second, and between those of the 
 eleventh and twelfth dorsal vertebrae. In the lumbar, between 
 the spines of the lumbar vertebrae. 
 
 These muscles extend between the transverse pro- 
 versales cesses in the cervical and lumbar regions. In the neck 
 they are arranged in pairs, like the interspinales, and 
 the corresponding cervical nerve separates one from the other. 
 In the loins they are four in number, and are arranged singly. 
 We have next to examine the muscles concerned in the movements 
 of the head upon the first and second cervical vertebrae 
 
 This is a largely developed interspinal muscle. It 
 capitis arises by a small tendon from the well-marked spine 
 
 posticus O f the second cervical vertebra, and, expanding con- 
 siderably, is inserted below the superior curved ridge 
 of the occipital bone; in other words, into the spine of the occi- 
 pital vertebra. These two recti muscles, as they ascend to their 
 insertions, diverge and leave an interval between them in which 
 are found the recti capitis postici minores. 
 
 -P This is also an interspinal muscle, but smaller than 
 
 pitis posticus the preceding. Arising from the feebly developed 
 spine of the first vertebra, it expands as it ascends, and 
 is inserted into the occipital bone between the inferior curved 
 ridge and the foramen magnum. The action of the two preceding 
 muscles is to raise the head. 
 
MUSCLES OF THE BACK. 207 
 
 This arises from the spine of the second vertebra, 
 an( ^ * s i nser t ea i* 1 * the transverse process of the first. 
 Its action is to rotate the first upon the second vertebra ; 
 in other words, to turn the head round. 
 
 This muscle arises from the transverse process of the 
 Obliquus rg t ver tebra, and ascending obliquely inwards is in- 
 serted in the interval between the curved ridges of 
 the occiput. Its action is to draw the occiput towards the spine. 
 
 Observe that the obliqui and recti muscles of one side form the 
 
 sides of a triangle, in which we find the branches of the suboccipital 
 
 or first cervical nerve, the vertebral artery, and the arch of the atlas. 
 
 This small muscle extends between the transverse 
 
 tiskteraHs" process of the first vertebra and the eminentia jugu- 
 
 laris of the occiput ; but since this eminence is the 
 
 transverse process of the occipital vertebra, the muscle must be 
 
 considered as an intertransverse one. 
 
 The posterior branches of the spinal nerves supply 
 thTback the muscles and skin of the back. They pass backwards 
 between the transverse processes of the vertebrae, and 
 divide into external and internal branches. The general plan 
 upon which these nerves are arranged is the same throughout the 
 whole length of the spine; but since there are certain peculiarities 
 deserving of notice in particular situations, we must examine each 
 region separately. 
 
 The posterior division of the first cervical nerve (the 
 suboccipital) passes between the arch of the atlas and 
 the vertebral artery, and divides into branches which 
 supply the recti and obliqui muscles concerned in the movement 
 of the head upon the first two vertebrae. It sometimes gives off 
 a cutaneous branch which accompanies the occipital artery, and is 
 distributed to the skin of the back of the scalp. 
 
 The posterior branch (the great occipital) of the second cervical 
 nerve is the largest of the series, and emerges between the arches 
 of the atlas and axis. It turns upwards beneath the inferior 
 oblique muscles, passes through the coraplexus, and runs with the 
 occipital artery to the back of the scalp. 
 
208 MUSCLES OF THE BACK. 
 
 The posterior divisions of the six lower cervical nerves divide 
 into external and internal branches. The external are small, and 
 terminate in the splenius, and the continuation of the erector 
 spinae, viz., the trachelo-niastoid, the transversalis colli, and the 
 cervicalis ascendens. The internal, by far the larger, proceed 
 towards the spines of the vertebrae ; those of the third, fourth, 
 and fifth lie between the complexus and the semispinalis,* and 
 after supplying the muscles terminate in the integument ; those of 
 the sixth, seventh, and eighth lie between the semispinalis and 
 the multifidus spinae, to which they are distributed. 
 
 The posterior divisions of the spinal nerves in this, 
 region region come out between the transverse processes and 
 
 the tendons attached to them. They soon divide into 
 external and internal branches. The external pass obliquely over 
 the levatores costarum, between the sacro-lumbalis and the longis- 
 simus dorsi ; and successively increase in size from above down- 
 wards. The upper six terminate in the erector spinae and the 
 levatores costarum ; the rest, after supplying these muscles, pass 
 through the latissimus dorsi, and become the cutaneous nerves of 
 the back. The internal successively decrease in size from above 
 downwards. They run towards the spine between the semispinalis 
 dorsi and the multifidus spinae. The upper six, after giving 
 branches to the muscles, perforate the trapezius and become 
 cutaneous nerves. The lower ones terminate in the muscles of the 
 vertebral groove. 
 
 The general arrangement of the nerves in this region 
 region*"* resembles that of the dorsal. Their external branches, 
 
 after supplying the erector spinae, become cutaneous and 
 terminate in the skin over the buttock. The internal branches 
 supply the multifidus spinae. 
 
 The posterior divisions of the spinal nerves in this 
 
 Sacral 
 
 come out of the spinal canal through the foramina in 
 
 region are small. With the exception of the last, they 
 
 # The posterior branches of the second, third, and fourth nerves are generally con- 
 nected, beneath the complexus, by branches in the form of loops. This constitutes the 
 posterior cervical plexus of some anatomists. 
 
MUSCLES OF THE BACK. 209 
 
 the back of the sacrum. The upper two or three divide into 
 external and internal branches. The internal terminate in the 
 multifidus spinse ; the external become cutaneous and supply the 
 skin of the gluteal region. The last two sacral nerves proceed, 
 without dividing, to the integument. 
 
 The coccygeal nerve is exceedingly small, and, after joining a 
 small branch from the last sacral, terminates in the skin.* 
 
 The vessels which supply the back are: 1. Small 
 branches from the occipital ; 2. Small branches from 
 the vertebral; 3. The deep cervical; 4. The posterior 
 branches of the intercostal and lumbar arteries. 
 
 The occipital artery furnishes several small branches to the 
 muscles at the back of the neck ; one, larger than the rest (called 
 arteria princeps cervicis), descends beneath the complexus, and 
 in some subjects inosculates with the deep cervical artery, and 
 with small branches from the vertebral. 
 
 The deep cervical artery is the posterior branch of the first in- 
 tercostal artery. It passes backwards between the transverse 
 process of the last cervical vertebra and the first rib : it then 
 ascends between the complexus and the semispinalis colli. 
 
 The posterior branches of the intercostal and lumbar arteries 
 accompany the corresponding nerves, and are in all respects similar 
 to them in distribution. Each sends a small branch into the 
 spinal canal. 
 
 The veins correspond to the arteries. 
 
 We have, lastly, to examine three muscles situated in 
 muscles. e d fr n t f t ne spine ; namely, the longus colli, the rectus 
 capitis anticus major, and the rectus capitis anticus 
 minor. In order to have a complete view of the two latter, a 
 special dissection should be made, before the head is removed 
 from the first vertebra. 
 
 Longus colli ^^ s m uscle is situated in front of the spine, and 
 
 extends from the third dorsal to the first cervical 
 
 vertebra. For convenience of description it is divided into three 
 
 * The branching of the posterior divisions of the seveial spinal nerves has been 
 accurately described by Mr. Ellis, Med. Gazette, Feb. 10, 1843. 
 
 r 
 
210 LIGAMENTS OF THE SPINE. 
 
 sets of fibres, of which one extends longitudinally from the body 
 of one vertebra to that of another; the two others extend ob- 
 liquely between the transverse processes and the bodies of the 
 vertebras. 
 
 The longitudinal portion of the muscle arises from the bodies 
 of the two or three upper dorsal and the two lower cervical vertebrae, 
 and is inserted into the bodies of the second, third, and fourth 
 cervical vertebrae. 
 
 The superior oblique portion, arising from the anterior tubercles 
 of the transverse processes of the third, fourth, and fifth cervical 
 vertebrae, ascends inwards, and is inserted into the front part or 
 body of the first cervical vertebra. The inferior oblique portion 
 proceeds from the bodies of the three upper dorsal vertebrae, and 
 is inserted into the transverse processes of the fifth and sixth 
 cervical vertebras. The action of this muscle, taken as a whole, 
 must be to bend the cervical region of the spine. Its nerves come 
 from the deep cervical and brachial plexuses. 
 
 This muscle arises from the anterior tubercles of 
 Bectus capitis the transverse processes of the third, fourth, fifth, and 
 
 JH1L1CU.S IHclJOr. A 
 
 sixth cervical vertebras, and is inserted into the basilar 
 process of the occipital bone, in front of the foramen magnurn. 
 
 This muscle arises from the root of the transverse 
 anTicus mmor P rocess of the first cervical vertebra, and is inserted 
 
 into the basilar process of the occipital bone, nearer to 
 the foramen magnum than the preceding muscle. The action 
 of the recti muscles is to bend the head forwards. They are 
 supplied with nerves from the deep cervical plexus. 
 
 LIGAMENTS OF THE SPINE. 
 
 The vertebras are connected by their intervertebral fibre-carti- 
 lages, by ligaments in front of and behind their bodies, and by 
 ligaments which extend between their arches and their spines. 
 Their articular processes have capsular ligaments, and synovial 
 membranes. 
 
LIGAMENTS OF THE SPINE. 211 
 
 Anterior ^is LS a strong band of longitudinal fibres which 
 
 common extends along the front of the bodies of the vertebrae 
 ligament. frQm the ^ tQ ^ Q sacrum. The fibres are not all of 
 equal length. The more superficial extend from one vertebra to 
 the fourth or fifth below it ; those a little deeper pass from one 
 vertebra to the second or third below it ; while the deepest of all 
 proceed from vertebra to vertebra. The ligament becomes broader 
 and stronger in proportion to the size of the vertebrae. By making 
 transverse incisions through it in different situations, we observe 
 that its fibres are more firmly adherent to the intervertebral 
 cartilages, and to the borders of the vertebrae, than to the middle 
 of the bones. 
 
 Inter- These bands of ligamentous fibres fill up the intervals 
 
 spinous between the spines of the dorsal and lumbar vertebrae. 
 1 s ' They are the most marked in the lumbar region. 
 Those fibres which connect the apices of the spines, being stronger 
 than the rest, are described as separate ligaments under the name 
 of supra-spinous. Their use is to limit the flexion of the spine. 
 These are called, on account of their colour, ligamenta 
 subflava. To obtain a good view of them, the arches 
 
 the arches of the vertebrae should be removed with a saw. They 
 P ass between the arches of the contiguous vertebrae, 
 
 from the axis to the sacrum ; none existing between the 
 occiput and the atlas, or between the atlas and axis. They are 
 composed of yellow elastic tissue, and their strength increases with 
 the size of the vertebrae. This elasticity answers a double pur- 
 pose : it not only permits the spine to bend forwards, but materi- 
 ally assists in restoring it to its curve of rest. They economise 
 muscular force, like the ligamentum nuchae in animals. 
 p . This extends longitudinally, in a similar manner to 
 
 common the anterior common ligament, along the posterior sur- 
 Lgament. ^ dcQ Q f ^ b 0( jj es o f j^e vertebrae, from the occiput to 
 the sacrum. 
 
 Interverte- ^is substance, placed between the bodies of the 
 bral fibro- vertebrae, is by far the strongest bond of connection 
 cartilage. between them, and fulfils most important purposes in 
 
 T> 2 
 
212 LIGAMENTS OF THE SPINE. 
 
 the mechanism of the spine. Its peculiar structure is adapted to 
 break shocks, and to render the spine flexible and resilient. To 
 see the structure of an intervertebral fibro-cartilage, a horizontal 
 section must be made through one of them. It is firm and resist- 
 ing near the circumference, but soft and pulpy towards the centre. 
 The circumferential portion is composed of concentric layers of 
 fibro-cartilage, placed vertically. These layers are attached by 
 their edges to the vertebrae ; they gradually decrease in number 
 from the . circumference towards the centre, and the interstices 
 between them are filled by the soft pulpy tissue. The central 
 portion is composed almost entirely of this pulpy tissue ; and it 
 bulges when no longer under pressure. Thus the bodies of the 
 vertebrae, in their motions upon each other, revolve upon a ball of 
 fluid tightly girt all round by bands of fibrous tissue. These 
 motions are regulated by the articular processes. 
 
 Dissect an intervertebral substance layer after layer in front, 
 and you will find that the circumferential fibres extend obliquely 
 between the vertebrae, crossing each other like the branches of the 
 letter X. 
 
 The thickness of the intervertebral cartilages is not the same in 
 front and behind. It is this difference in their thickness, more 
 than that in the bodies of the vertebra?, which produces the several 
 curves of the spine. In the lumbar and cervical regions they are 
 thicker in front ; in the dorsal region behind.* 
 
 * The structure of the intervertebral cartilages explains the well-known fact, that a 
 man becomes shorter after standing for some hours ; and that he regains his usual 
 height after rest. The difference between the morning and evening stature amounts 
 to more than half an inch. 
 
 It also explains the fact that a permanent lateral curvature of the spine may be 
 produced (especially in the young) by the habitual practice of leaning to this or that 
 side. Experience proves that the cause of lateral curvature depends more frequently 
 upon some alteration in the structure of the fibro-cartilages than upon the bones. 
 From an examination of the bodies of one hundred and thirty-four individuals with 
 crooked spines, it was concluded that in two-thirds the bones were perfectly healthy ; 
 that the most frequent cause of curvature resided in the invertebral substances ; these 
 being, on the concave side of the curve, almost absorbed, and on the convex side pre- 
 ternaturally developed. As might be expected in these cases, the muscles on the 
 convex side become lengthened, and degenerate in structure. On this subject see 
 Hildclrandfs Anatomic, B. ii. s. 155. 
 
LIGAMENTS CONNECTING THE HEAD TO THE SPINE. 213 
 
 Capsular Each joint between the articular processes has a cap- 
 
 ligaments, sular ligament and a synovial membrane. The surfaces 
 of the bones are crusted with cartilage. 
 
 Inter- These are thin bands of fibres which pass between 
 
 transverse the transverse processes of the vertebrae. They are 
 igaments. rudimentary in the cervical region, and are sometimes 
 absent. 
 
 Motions of Though but little movement is permitted between 
 the spine. anv two vertebrae (the atlas and axis excepted), yet the 
 collective motion between them all is considerable. The spine can 
 be bent forwards, backwards, or on either side ; it also admits of 
 slight rotation. In consequence of the elasticity of the inter- 
 vertebral cartilages and the ligamenta subflava, it returns spon- 
 taneously to its natural curve of rest like an elastic bow. Its 
 mobility is greatest in the cervical region, on account of the 
 thickness of the fibro-cartilages, the small size of the vertebra^ 
 the oblique direction of their articulations, and, above all, the 
 horizontal position and the shortness of their spines. In the 
 dorsal region there is very little mobility, on account of the 
 vertical direction of the articular processes, and the manner in 
 which the arches and the spines overlap each other. In the 
 lumbar region, the spine again becomes more movable, on account 
 of the thickness of the intervertebral cartilages, and the horizontal 
 direction of the spinous processes. 
 
 Li ments ^ ie occ ip u ^ ^ s connected to the atlas by an anterior 
 between the (occipito-atlantoid) membrane which passes from the 
 bonfand foramen magnum to the front part of the atlas. The 
 the first thickest part of this is in the middle. A posterior 
 (occipito-atlantoid) membrane extends in a similar 
 manner from the posterior border of the foramen magnum to the 
 arch of the atlas. It is perforated by the vertebral artery and the 
 suboccipital nerve. The movements which take place between 
 these bones are flexion and extension, as in nodding forwards and 
 backwards ; and lateral movement, as in inclining the head 
 sideways. 
 
214 LIGAMENTS CONNECTING THE HEAD TO THE SPINE. 
 
 Ligaments 
 between the 
 occipital 
 bone and 
 flie axis. 
 
 These are the most important ; and to see them, the 
 spinal canal must be exposed by removing the arches 
 of the upper cervical vertebrae, and the posterior com- 
 mon ligament, which is here very thick and strong. It 
 descends from the basilar process of the occipital bone 
 over the odontoid and transverse ligaments. 
 
 The odontoid or check ligaments (fig. 44) are two 
 or check very strong ligaments which proceed from the sides of 
 ligaments. ^ Q odontoid process to the tubercles on the inner sides 
 of the condyles of the occiput. Their use is to limit the rotation 
 of the head. A third or middle odontoid ligament passes from 
 
 Fig. 44. 
 
 POST? COMMON LICT 
 
 DIAGBAM OF THE ODONTOID AND TRANSVEKSE LIGAMENTS. 
 
 the apex of the odontoid process to the margin of the foramen 
 magnum. It is sometimes called the ligamentum suspensorium. 
 The odontoid process of the axis forms a pivot upon 
 which the head and atlas rotate. The most important 
 ligament is the transverse (fig. 44). It passes behind 
 the odontoid process, and is attached to the tubercles 
 on the inner side of the articular processes of the atlas. 
 From the centre of this ligament a few fibres pass upwards, and 
 
 Articula- 
 tion be- 
 tween the 
 atlas and 
 the axis. 
 
LIGAMENTS OF THE RIBS. 215 
 
 others downwards, giving it a cruciform appearance.* Thus it 
 forms with the atlas a ring, into which the odontoid process is 
 received. If this transverse ligament be divided, we observe that 
 the odontoid process is covered with cartilage in front and behind, 
 and is provided with two synovial membranes. 
 Articulation All the ribs, with the exception of the first and the 
 of the ribs, two last, are articulated with the bodies of two vertebrae, 
 and with the transverse processes. 
 
 The head of each rib presents two articular surfaces, correspond- 
 ing to the bodies of two vertebras. There are two distinct articu- 
 lations, each provided with a separate synovial membrane The 
 ligaments are: 1. An anterior, which connects the head of the 
 rib with the vertebrae, and with the intervening fibro-cartilage : 
 this, on account of the divergence of its fibres, is called the ' stel- 
 late ' ligament. 2. An inter-articular, which proceeds from the 
 head of the rib to the intervertebral cartilage. 
 
 The tubercle of the rib articulates with the transverse process. 
 This articulation has a capsular and synovial membrane, and is 
 secured by the following ligaments: 1. The posterior costo- 
 transverse passes from the apex of the transverse process to the 
 apex of the tubercle of the rib. 2. The middle costo-transverse 
 connects the neck of the rib to the front surface of the transverse 
 process. 3. The anterior costo-transverse ascends from the neck 
 of the rib to the lower border of the transverse process above it. 
 
 The head of the first rib articulates with a single vertebra. 
 
 The eleventh and twelfth ribs articulate each with a single 
 vertebra, and are not connected to the transverse processes. 
 
 The cartilages of all the true ribs are received into 
 between the slight concavities on the side of the sternum. In young 
 cartilages of subjects we find that the cartilages of the six lower true 
 the sternum. T ^ s have distinct articulations provided with synovial 
 membranes. They are secured in front and behind by 
 strong ligamentous fibres, which proceed from the cartilages and 
 radiate upon the sternum, crossing those of the opposite side. 
 
 * This is not shown in the diagram. 
 
216 
 
 LIGAMENTS OF THE LOWER JAW. 
 
 The costal cartilages from the sixth to the tenth are connected 
 by ligamentous fibres. 
 
 Articulation ^ e con( tyl e ^ tlie l wer j aw articulates with the 
 of the lower glenoid cavity of the temporal bone. The joint is 
 jaw. provided with an inter-articular fibro-cartilage, and 
 
 with external and internal lateral ligaments (fig. 45). 
 
 Fig. 45. 
 
 Section through the glenoid cavity 
 
 Inter-articular nbro-cartilage 
 
 Internal lateral ligament 
 
 TRANSVERSE SECTION TO SHOW THE LIGAMENTS AND THE FIBRO-CARTILAGE OF THE 
 JOINT OF THE LOWER JAW. THE DOTTED LINES REPRESENT THE TWO SYNOVIAL 
 MEMBRANES. 
 
 The external lateral ligament extends from the tubercle of the 
 zygoma downwards and backwards to the tubercle of the condyle 
 of the jaw. 
 
 The internal lateral ligament extends from the spinous process 
 of the sphenoid bone to the border of the dental foramen. This 
 * so-called ' ligament cannot in any way contribute to the strength 
 of the joint : the articulation of one side performs the office of 
 internal lateral ligament to the other. 
 
THE DISSECTION OF THE ARM. 217 
 
 The inter-articular fibro-cartilage is of an oval form, and thicker 
 at the margin than at the centre. It is connected on the outer 
 side to the external lateral ligament, and on the inner side some 
 of the fibres of the external pterygoid are inserted into it. 
 
 There are two synovial membranes for the joint. The larger 
 and looser of the two is situated between the glenoid cavity and 
 the fibro-cartilage. The other is interposed between the fibro- 
 cartilage and the condyle of the jaw. They sometimes communi- 
 cate through a small aperture in the centre of the fibro-cartilage. 
 
 The form of the articulation of the lower jaw admits of motion 
 upwards and downwards, forwards and backwards, and from 
 side to side. A combination of these motions takes place in 
 mastication: during this act the condyles of the jaw describe an 
 oblique rotatory movement upon the glenoid cavity. The purposes 
 served by this fibro-cartilage in this joint are, that it follows the 
 condyle, and adapts a convenient socket for all its movements ; 
 and that, being elastic, it breaks shocks ; for shocks here would 
 be almost fatal, considering what a thin plate the glenoid cavity 
 is, and that just above it is the brain. 
 
 THE DISSECTION OF THE AEM. 
 
 The arm being placed at right angles with the body, make 
 three incisions through the skin: the first, along the middle of 
 the sternum ; the second, along the clavicle and down the front of 
 the arm for about four inches ; the third, from the ensiform 
 cartilage vertically downwards, to the posterior border of the 
 axilla. 
 
 The skin should be carefully separated from the subjacent layer 
 of adipose tissue (called the superficial fascia). In doing so, 
 unless the subject be very muscular, you will scarcely notice the 
 thin pale fibres of the broad cutaneous muscle of the neck ( ( pla- 
 tysma myoides,' p. 13), which arises in this tissue. 
 Cutaneous The numerous nerves which run through the sub- 
 nerves, cutaneous tissue to the skin and mammary gland must 
 
218 PECTORAL REGION. 
 
 be carefully dissected. They are derived from various sources : 
 some, branches of the superficial cervical plexus, descend over the 
 clavicle ; others, branches of the intercostal nerves,- come through 
 the intercostal spaces close to the sternum, with a small artery ; a 
 third series, also branches of the intercostal nerves, come out on 
 the side of the chest, and run forwards over the outer border of 
 the pectoralis major. 
 
 The supra-clavicular nerves, which descend over the clavicle, 
 are subdivided, according to their direction, into sternal, cla- 
 vicular, and acromial branches (diagram, p. 15). The sternal 
 cross the inner end of the clavicle to supply the skin over the 
 upper part of the sternum. The clavicular pass over the middle 
 of the clavicle, and supply the integument over the front of the 
 chest and the mammary gland. The acromial branches cross 
 over the outer end of the clavicle, and distribute their filaments to 
 the skin of the shoulder. 
 
 Near the sternum you find the anterior cutaneous branches of 
 the intercostal nerves. After traversing the pectoralis major, each 
 nerve sends a filament to the skin over the sternum, and a larger 
 one, which supplies the skin, over the pectoral muscle. 
 
 Branches of the internal mammary artery, for the supply of the 
 mammary gland, accompany these nerves. During lactation they 
 increase in size, ramifying tortuously over the surface of the 
 gland. I have seen them nearly as large as the radial at the wrist. 
 They would require a ligature in removal of the breast. 
 
 The lateral cutaneous branches of the intercostal nerves come 
 out between the digitations of the serratus magnus on the side of 
 the chest. They will be more fully described presently. 
 
 Remove the superficial fascia with the mammary gland from 
 the pectoralis major, by dissecting parallel to the course of the 
 fibres. When the muscle has been fully exposed, observe its 
 shape, the course of its fibres, their origin and insertion. 
 Pectoralis The pectoralis major is the great triangular muscle 
 
 major. on the front of the chest. It arises from the sternal 
 
 half of the clavicle, from the front of the sternum, from the carti- 
 lages of all the true ribs except the last, and from the aponeurosis 
 
PECTORAL REGION. 219 
 
 of the external oblique muscle of the abdomen. The fibres con- 
 verge towards the arm, and terminate in a flat tendon, about two 
 inches in breadth, which is inserted into the anterior margin of 
 the bicipital groove of the humerus. Their arrangement, as well 
 as the structure of their tendon, is peculiar. The lower fibres 
 which form the boundary of the axilla are folded beneath the rest, 
 and terminate upon the upper part of the tendon, i.e. nearer to 
 the shoulder joint ; whereas the upper fibres, which arise from 
 the clavicle, and are frequently separated from the main body of 
 the muscle by a slight interval, descend in front of the lower, and 
 terminate upon the lower part of the tendon. Consequently the 
 upper and lower fibres of the muscle cross each other previously 
 to their insertion. 
 
 The object of this arrangement is to enable all the fibres to act 
 simultaneously when the arm is extended. 
 
 The upper part of the tendon sends off an ( aponeurosis,' 
 which straps down the long head of the biceps, and is attached 
 to the great tuberosity of the humerus. A second expansion is 
 prolonged backwards to the tendon of the deltoid muscle, and 
 a third is intimately connected with the fascia of the upper 
 arm. 
 
 The chief action of the pectoralis major is to draw the humerus 
 towards the chest : as in placing the hand on the opposite shoulder, 
 or in pulling an object towards the body. When the arm is raised 
 and made the fixed point, the muscle assists in raising the trunk, 
 as in climbing. 
 
 Between the pectoralis major and the deltoid, the great muscle 
 of the shoulder, is an interval varying in extent in different sub- 
 jects, but always more marked towards the clavicle. It contains 
 a small artery the thoracica humeraria and the cephalic vein, 
 which ascends on the outer side of the arm, and empties itself 
 into the axillary. This interval is the proper place to feel for the 
 coracoid process. In doubtful injuries about the shoulder, this 
 point of bone is a good landmark in helping the surgeon to arrive 
 at a correct diagnosis. 
 
 The pectoralis major is supplied with nerves by the anterior 
 
220 PECTORAL REGION. 
 
 thoracic branches of the brachial plexus ; with blood, by the long 
 and short thoracic branches of the axillary artery. 
 
 Reflect from the clavicle, the clavicular portion of 
 
 Anatomy of ,. _. . , . , . 
 
 the infra- the pectoralis major, and in doing so, a small nerve, 
 clavicular the an terior thoracic, must be noticed entering the 
 under surface of the muscle. Beneath the portion so 
 reflected, part of the pectoralis minor will be exposed. Between 
 the upper border of this muscle and the clavicle, is an important 
 space, in which you must dissect and examine the relative position 
 of the following objects 
 
 c a. A strong ligamentous expansion, called the costo- 
 
 coracoid coracoid fascia, which extends from the cartilage of 
 fascia. ^e rg f. j^j-j ^ th e coracoid process. Between these 
 
 points it is attached to the clavicle, and forms a complete invest- 
 ment for the subclavius muscle. It presents a crescent-shaped 
 edge, which arches over, and protects the axillary vessels and 
 nerves : from this edge is prolonged a fascia, which passes in front 
 of the axillary vessels forming the anterior portion of their sheath ; 
 the posterior being formed by a prolongation of the deep cervical 
 fascia. The front portion of this sheath is perforated by the 
 cephalic vein, thoracica acromialis artery, and anterior thoracic 
 nerve. This fascia must be removed. 
 
 b. The subclavius muscle enclosed in its fibrous sheath. 
 
 c. The axillary vein, artery, and brachial plexus of nerves. 
 
 d. A short arterial trunk (the thoracic axis), which divides into 
 several radiating branches. 
 
 e. The termination of the cephalic vein in the axillary. 
 
 /. Two nerves (the anterior thoracic), which descend from the 
 brachial plexus below the clavicle, cross in front of the axillary 
 vessels to supply the pectoral muscles. 
 
 This muscle lies between the clavicle and the first 
 rib. It arises from the cartilage of the first rib by a 
 round tendon, and is inserted into a groove on the under surface 
 of the clavicle between its two tubercles. Its nerve comes from 
 the brachial plexus. Its action is to depress the clavicle, and 
 prevent its too great elevation. 
 
PECTORAL REGION. 221 
 
 In the space now before us are the great vessels and 
 
 Relative po- ne rves of the axilla in the first part of their course. 
 
 sition ot the . A 
 
 axillary They lie at a great depth from the surface. They 
 vessels and are surrounc l e (l by a sheath of fascia, which descends 
 with them beneath the clavicle, and are situated with 
 regard to each other in the following manner. The axillary vein 
 lies in front of the artery, and rather to its thoracic side. The 
 axillary (brachial) plexus of nerves is situated above the artery, 
 and on a posterior plane. The plexus consists of two, or some- 
 times three large cords, which result from the union of the an- 
 terior branches of the last four cervical and the first dorsal. 
 Thoracic This is the first branch of the axillary artery. It 
 
 axis. comes off above the pectoralis minor, and soon divides 
 
 into three branches the superior or short thoracic, the thoracica 
 humeraria, and the thoracica acromialis. The superior or short 
 thoracic runs between the pectoralis major and minor, supplying 
 ramifications to both, and anastomosing with the intercostal and 
 internal mammary arteries. The thoracica humeraria descends 
 with the cephalic vein, in the interval between the pectoralis 
 major and deltoid, and ramifies in both. The thoracica acromialis 
 passes over the coracoid process to the under surface of the deltoid, 
 which it supplies, and communicates with the circumflex branches 
 of the axillary. All these arteries are accompanied by veins, 
 which most frequently empty themselves into the cephalic, but 
 occasionally into the axillary vein itself. 
 
 Cephalic The cephalic vein is one of the principal cutaneous 
 
 vem. veins of the arm. Commencing on the back of the 
 
 thumb and forefinger, it runs up the radial side of the forearm, 
 over the front of the elbow-joint; thence ascending along the 
 outer edge of the biceps, it runs up the interval between the 
 pectoralis major and deltoid, pierces the costo-coracoid fascia, and 
 finally empties itself into the axillary vein.* 
 
 * The cephalic vein, in some cases, runs over the clavicle to join the external 
 jugular; or there may be a communication (termed jugulo-cephalic) between these 
 
222 DISSECTION OF THE AXILLA. 
 
 Anterior These nerves come from the brachial plexus, to supply 
 
 thoracic the pectoral muscles. There are generally two an 
 
 external and an internal one for each pectoral muscle 
 
 (p. 62). The external arises from the outer cord of the brachial 
 
 plexus, passes over the axillary artery, and supplies the pectoralis 
 
 *JL& Ik* major ; the internal comes from the internal cord, and emerges 
 
 f^o^ between the axillary artery and vein, to enter the under surface 
 
 ^> of the pectoralis minor. 
 
 From this view of the relations of the axillary artery 
 ~ Difficulty of j n {.;h e rs f. p ar jt-g course ^ gome idea may be formed 
 
 first part of of the difficulty of passing a ligature round it in this 
 situation. In addition to its great depth from the sur- 
 face, varieties sometimes occur in the position of the 
 nerves and veins, which would render the operation still more 
 embarrassing. For instance, the anterior thoracic nerves may be 
 more numerous than usual, and form by their mutual communi- 
 cation a plexus around the artery. A large nerve is often seen 
 crossing obliquely over the artery, immediately below the clavicle, 
 to form one of the roots of the median nerve. The cephalic vein 
 , may ascend higher than usual, and open into the subclavian; 
 and, as it receives large veins corresponding to the thoracic axis, 
 a concourse of veins would be met with in front of the artery. 
 Again, it is by no means uncommon to find a deep-seated vein 
 (e.g. the supra-scapular) crossing over the artery to join the 
 j^ axillary vein. 
 
 DISSECTION OF THE AXILLA. 
 
 The skin having already been reflected, it is necessary to notice 
 the axillary sebaceous glands, and afterwards to make out the 
 axillary fascia. 
 
 Sebaceous ^ n close contact with the skin, near the roots of the 
 
 glands. hairs in the axilla, are numerous sebaceous glands. 
 They are of a reddish brown colour, and rather larger than a 
 pin's head. 
 
DISSECTION OF THE AXILLA. 223 
 
 Axillary Tnis tough membrane, which lies immediately be- 
 
 fascia. neath the skin of the axilla, is a continuation of the 
 
 general investment of the muscles. It closes in and forms the 
 floor of the cavity of the axilla. Externally it is strengthened by 
 fibres from the tendons of the pectoralis major and latissimus 
 dor si, and is continuous with the fascia of the arm ; internally, it 
 is prolonged on the side of the chest, over the serratus magnus 
 muscle ; in front and behind, it divides so as to inclose between 
 its layers the muscles which form the boundaries of the axilla. 
 Thus the anterior layer incloses the two pectoral muscles, and is 
 connected with the coracoid process, the costo-coracoid ligament, 
 and the clavicle ; the posterior layer incloses the latissimus dorsi, 
 and passes backwards to the spine. 
 
 A subcutaneous artery, sometimes of considerable size, often 
 runs in the substance of the axillary fascia. It generally arises 
 from the brachial, or from the lower part of the axillary, and runs 
 across the floor of the axilla towards the lower edge of the pecto- 
 ralis major. So far as I know, it has not hitherto been named; 
 but it is worth remembering, because it would occasion much 
 haemorrhage if wounded in opening an abscess. 
 Contents of Remove the axillary fascia, and display the boundaries 
 axilla. and the contents of the axilla. The dissection of this 
 
 cavity is difficult, and you must proceed cautiously. Bear in mind 
 that the trunk blood-vessels and nerves run through the upper 
 part of the axilla ; that the long thoracic artery runs along the 
 anterior border, and the subscapular artery along the posterior. 
 Commence working, therefore, in the middle ; break down with 
 the handle of the scalpel the loose connective tissue, fat, and 
 absorbent glands, which occupy the cavity. You will soon dis- 
 cover some cutaneous nerves coming out between the ribs, and 
 then crossing the axillary space. These nerves are the lateral 
 cutaneous branches of the intercostal nerves ; they perforate the 
 intercostal spaces between the digitations of the serratus magnus, 
 midway between the sternum and the spine, and divide into 
 anterior and posterior branches. The anterior turn over the 
 pectoralis major, to supply the skin on the front of the chest and 
 
224 DISSECTION OF THE AXILLA. 
 
 the mammary gland. The posterior pass backwards over the 
 latissimus dorsi, and are distributed to the skin covering this 
 muscle and the scapula. 
 
 Intercosto- ^ ie P er f ra ting branch of the second intercostal 
 humeral nerve requires a special description ; it is larger than 
 
 the others, and is called the ' intercosto-humeralS be- 
 cause it supplies the integuments of the arm. It comes through 
 the second intercostal space, traverses the upper part of the axilla, 
 where it receives a branch of the lesser internal cutaneous nerve 
 (nerve of Wrisberg), and terminates in filaments, which are dis- 
 tributed to the skin on the inner side of the arm, as low as the 
 internal condyle. The perforating branch of the third intercostal 
 is also an ' intercosto-humeral ' nerve. It receives a branch from 
 the second, and runs a similar course. The distribution of these 
 nerves may account for the pain down the arm which is sometimes 
 experienced in pleurisy. 
 
 Boundaries The axilla may be described as a conical space, of 
 of the axilla, which the summit is beneath the clavicle, and the base 
 between the pectoralis major and the latissimus dorsi. Now, 
 what are its boundaries ? On the inner side, it is bounded by the 
 ribs, covered by the serratus magnus ; on the outer side by the 
 humerus, covered by the coraco-brachialis and biceps ; in front 
 by the pectoralis major and minor; behind by the latissimus 
 dorsi, teres major, and subscapularis. Its anterior and posterior 
 boundaries converge from the chest, so that the axilla becomes 
 narrower towards the arm. With a full view of the axilla before 
 you, think what serious consequences may follow suppuration 
 here ; the matter may burrow under the pectoral muscles, or under 
 the scapula, or it may run up beneath the clavicle and point in 
 the neck. 
 
 Axillary The axillary glands form a continuous chain beneath 
 
 absorbent the clavicle, with the cervical glands. They are from 
 
 twelve to fifteen in number, of a reddish brown colour, 
 and variable size. Most of them lie near some large blood-vessel ; 
 others are imbedded in the loose tissue of the axilla ; sometimes 
 one or two small ones are observed along the lower border of the 
 
DISSECTION OF THE AXILLA. 225 
 
 pectoralis major. They are supplied with blood by a branch 
 (thoracica alaris) of the axillary artery, and by branches from 
 the thoracic and infra-scapular arteries. 
 
 These glands receive the absorbents from the arm, from the 
 front and side of the chest, and from the outer half of the mam- 
 mary gland. 
 
 Now reflect the pectoralis major from its origin, to expose the 
 pectoralis minor, and the ramifications of the short and long 
 thoracic arteries. Preserve the arteries as much as possible in 
 connection with the main trunks. 
 
 Pectoralis This muscle arises from the third, fourth, and fifth 
 
 minor. r {\) S) near the costal cartilages. The fibres run up- 
 
 wards and outwards, and converge to a strong tendon, which is 
 inserted into the anterior surface of the coracoid process. The 
 tendon is connected to that of the coraco-brachialis by a strong 
 fascia, which forms a protection for the subjacent axillary vessels 
 and nerves. The action of this muscle is to draw the scapula 
 downwards and forwards. 
 
 Latissimus This muscle forms the posterior margin of the axilla. 
 dorsi. It arises from the crest of the ilium, from the spines 
 
 of the two or three upper sacral, all the lumbar, and six lower 
 dorsal vertebra, and by digitations from the three lower ribs, 
 corresponding with those of the external oblique. It is inserted 
 by a broad flat tendon (which runs behind the axillary vessels and 
 nerves), into the bottom of the bicipital groove of the humerus. 
 
 This muscle lies behind the latissimus dorsi, is 
 maj r< closely connected with it, and assists in forming the 
 posterior boundary of the axilla. It arises from the lower angle of 
 the back of the scapula, and is inserted by a broad flat tendon into 
 the posterior margin of the bicipital groove of the humerus. A 
 bursa or sac, containing serum, to prevent friction, intervenes 
 between this tendon and that of the latissimus dorsi. The action 
 of this and the preceding muscle is to draw the humerus inwards 
 and backwards. 
 
 This muscle occupies the internal surface of the 
 Subscapularis. scapula> It ar i ses f rom the internal surface of the 
 
 Q 
 
226 DISSECTION OF THE AXILLA. 
 
 scapula, with the exception of the angles and neck, and terminates 
 in a strong tendon, which passes under the axillary vessels and 
 nerves, over the inner side of the shoulder-joint, and is inserted 
 into the lesser tuberosity of the humerus. The tendon of the 
 muscle is intimately connected with the capsular ligament of the 
 shoulder-joint, and between the coracoid process and the tendon 
 is a bursa, which frequently communicates with the joint. Its 
 action is to rotate the humerus inwards. 
 
 Serratus This muscle covers the side of the chest like a girth. 
 
 magnus. It arises from the eight upper ribs by nine slips or 
 digitations, the second rib having two. Its fibres converge and 
 are inserted into the posterior border of the scapula. Its action 
 is to draw the scapula forwards ; but of this more hereafter. It 
 is supplied by the following nerve, which you see on its outer 
 surface. 
 
 This nerve supplies the serratus magnus only. It 
 
 respiratory comes from the fifth and sixth cervical nerves ; and 
 
 nerve of after passing through the scalenus medius, runs behind 
 
 the axillary vessels, to the outer surface of the serratus 
 
 magnus ; each digitation receiving a separate filament.* 
 
 Having surveyed the muscles which bound the axilla, study 
 next the axillary artery, and its branches : to this end, reflect the 
 subclavius from its insertion, and the pectoralis minor from its 
 origin. 
 
 This artery, a continuation of the subclavian, takes 
 
 Course and ^he name o f 'axillary' at the outer border of the 
 
 relations 7 
 
 of the first rib. It runs downwards and outwards, through 
 
 axillary ^ e U pp er part of the axilla, beneath the two pectoral 
 muscles, and along the inner edge of the coraco-bra- 
 chialis, as far as the lower border of the tendon of the teres 
 major, where it takes the name of 'brachial.' Its course may 
 be divided into three portions : one above the pectoralis minor ; 
 one behind it; and the third below it. The artery in the 
 
 * It may be asked why this nerve is called the ' external respiratory.' It was so 
 named by Sir C. Bell, who considered the serratus magnus as the external respiratory 
 muscle. 
 
DISSECTION OF THE AXILLA. 227 
 
 first part of its course is covered by the pectoralis major and 
 the costo-coracoid sheath ; and is crossed by the cephalic vein. 
 On the inner side is the axillary vein ; on the outer, the brachial 
 plexus of nerves ; and behind it, is the first intercostal space 
 and the second digitation of the serratus magnus. In the second 
 part, it lies behind the pectoralis minor ; on its inner side is the 
 axillary vein, separated however from the artery by the brachial 
 plexus, which here surrounds the artery. The artery rests upon 
 loose cellular tissue. In the third part, i.e. below the pectoralis 
 minor, the artery lies upon the subscapularis, and then upon the 
 tendons of the latissimus dorsi and teres major. On the outer 
 side is the coraco-brachialis ; on its inner side, the axillary vein. 
 The brachial plexus here breaks up into its various divisions, 
 which are generally arranged in the following manner : in front 
 of the artery are the two roots of the median nerve, which con- 
 verge like the letter V ; on the outer side are the musculo-cutane- 
 ous and external root of the median ; on the inner, the ulnar, the 
 two internal cutaneous, and the internal root of the median; 
 behind it, the musculo-spiral and circumflex nerves, 
 -o , f The number and origin of these branches often vary, 
 the axillary but their general course is in most cases similar, and 
 aitery. they usually arise in the order in which they are here 
 described. 
 
 The thoracic axis arises above the pectoralis minor, and divides 
 into branches, which have been already described (p. 221). 
 
 The alar thoracic is variable in its origin, supplies the glands 
 and cellular tissue of the axilla 
 
 The inferior or long thoracic artery, sometimes called the ex- 
 ternal mammary, runs along the lower border of the pectoralis 
 minor. It supplies the mammary gland, the serratus magnus and 
 pectoral muscles, and maintains a free anastomosis with the short 
 thoracic, internal mammary, and intercostal arteries. 
 
 The subscapular is the largest branch of the axillary ; it arises 
 opposite the lower border of the subscapularis, and soon divides 
 into an anterior and posterior branch. 
 
 a. The anterior branch is the continued trunk ; it runs along 
 
 Q 2 
 
228 DISSECTION OF THE AXILLA. 
 
 the anterior edge of the subscapularis towards the lower angle of 
 the scapula. Its numerous branches supply the subscapularis, 
 latissimus dorsi, and serratus magnus, and anastomose with the 
 intercostal and thoracic arteries, as well as the posterior scapular 
 (a branch of the subclavian). 
 
 b. The posterior branch (dorsalis scapulae) runs to the back of 
 the scapula, through a triangular space, bounded in front by the 
 
 PLAN OF THE BRANCHES OF THE AXILLARY ARTERY. 
 
 1. Thoracic axis, giving off 6. Subscapular. 
 
 2. Short thoracic. 7. Dorsalis scapulae. 
 
 3. Thoracica acromialis. 8. Anterior circumflex. 
 
 4. Thoracica humeraria. 9. Posterior circumflex. 
 5. Long thoracic. 
 
 long head of the triceps; below, by the teres major; and above, 
 by the subscapular and teres minor (diagram, p. 229). On the 
 back of the scapula, it divides into branches, which ramify close 
 to the bone, supplying the infra-spinatas and teres minor, and 
 anastomose with the supra -scapular and posterior scapular arteries 
 (diagram, p. 60). The subscapular vein empties itself into the 
 axillary vein. 
 
 There are two circumflex arteries an anterior and 
 
 Anterior and . ., . . . . 
 
 posterior a posterior, so called from the manner in wnicn they 
 circumflex encircle the neck of the humerus. The posterior cir- 
 
 artenes. 
 
 cum/lex artery is as large as the subscapular, close to 
 which it is given off; or both may arise from a common trunk 
 from the axillary. It passes backwards through a quadrilateral 
 
DISSECTION OF THE AXILLA. 
 
 229 
 
 space, bounded above by the subscapularis and teres minor, below 
 by the teres major, externally by the neck of the humerus, and 
 internally by the long head of the triceps (fig. 47). It then winds 
 round the back of the neck of the humerus, and is distributed to 
 the under surface of the deltoid. 
 
 Fig. 47. 
 
 DIAGRAM OF THE ORIGINS OF THE TRICEPS. 
 
 1. Subscapularis. 
 
 2. Teres major. 
 
 3. Long head of triceps. 
 
 4. Square space for circumflex a. and n. 
 
 5. Triangular space for dorsalis scapulae a. 
 C. Space for musculo-spiral n., and superior 
 prof unda a. 
 
 Besides the deltoid, the posterior circumflex artery supplies the 
 long head of the triceps, the head of the humerus, and the shoulder- 
 joint. It inosculates above with the acromio-thoracic and supra- 
 scapular arteries, below with the ascending branch of the superior 
 profunda (a branch of the brachial), and in front with the anterior 
 circumflex artery. If you cannot find the posterior circumflex 
 artery in its normal position, look for it (as a branch of the 
 brachial) below the tendon of the teres major. 
 
 The anterior circumflex artery, much smaller than the pos- 
 terior, runs in front of the neck of the humerus, above the tendon 
 of the latissimus dorsi. It passes directly outwards beneath the 
 coraco-brachialis and short head of the biceps, close to the bone, 
 
230 DISSECTION OF THE AXILLA. 
 
 and terminates in the under surface of the deltoid, where it 
 inosculates with the posterior circumflex artery. 
 
 The most remarkable branch of the anterior circumflex artery 
 is one which runs with the long tendon of the biceps up the 
 groove of the humerus, and is called, on that account, the bicipital 
 artery. It supplies the shoulder-joint and the neck of the 
 humerus. 
 
 Axillary The axillary vein is formed by the junction of the 
 
 vein. venae comites of the brachial artery, near the lower 
 
 border of the subscapularis. It receives the subscapular and the 
 other veins corresponding to the branches of the axillary artery, 
 with the exception of the circumflex, which usually join either the 
 subscapular or one of the venae comites. The axillary also receives 
 the cephalic, and sometimes the basilic vein. 
 
 The axillary vein in the first part of its course lies in front of 
 the artery, and close to its sternal side ; in the lower two thirds of 
 its course the vein lies still to the sternal side of the artery, but is 
 separated from it by some of the nerves of the brachial plexus. 
 
 This plexus is formed by the anterior branches of 
 brachial the four lower cervical and first dorsal nerves, and 
 
 plexus of receives also a small communicating branch from the 
 nerves. 
 
 fourth cervical nerve. The plexus is broad at the 
 
 lower part of the neck, where it emerges between the anterior and 
 middle scalene muscles ; but it gradually contracts as it descends 
 beneath the clavicle into the axilla. 
 
 The arrangement of the nerves in the formation of the plexus is 
 usually thus : The fifth and sixth cervical unite to form a single 
 cord ; the eighth cervical and the first dorsal form another cord ; 
 the seventh cervical runs for a short distance alone, and then splits 
 into two branches, one 'of which joins the cord formed by the fifth 
 and sixth cervical, the other, that formed by the eighth cervical 
 and fir^t dorsal. The branch joining the trunk formed by the 
 eighth cervical and first dorsal usually receives a large reinforce- 
 ment from the conjoined fifth and sixth cervical. Thus two great 
 trunks are formed, which lie for some distance above and to the 
 outer side of the subclavian artery. Beneath the clavicle, a third 
 
DISSECTION OF THE AXILLA. 
 
 231 
 
 cord is formed by the junction of a fasciculus from each of the two 
 primary trunks, so that in the axilla there are three large cords, 
 
 Fig. 48. 
 
 DIAGRAM OF THE BRACHIAL PLEXUS OF NERVES, AND THEIR RELATION TO THE 
 AXILLARY ARTERY. 
 
 1. Ulnar. 
 
 2. Internal cutaneous. 
 
 3. Lesser int. cutaneous (n. of Wris- 
 
 berg). 
 
 4. Musculo-spiral. 
 
 5. N. to latissimus dorsi. 
 
 6. N. to teres major. 
 
 7. N. to subscapularis. 
 
 8-9. Anterior thoracic n. to pectoral 
 muscles. 
 
 10. N. to serratus magnus. 
 
 11. Median. 
 
 12. Circumflex. 
 
 13. External cutaneous. 
 
 14. Supra-scapular. 
 
 15. Posterior scapular. 
 
 one external to the axillary artery, one internal to it, the third 
 behind it.* 
 
 The axillary plexus gives off some branches above the clavicle ; 
 these were dissected with the neck (p. 63). Below the clavicle, 
 it gives off the following : 
 
 From the outer cord, an anterior thoracic branch, the external 
 
 * This seems, from a number of dissections, to be the most frequent arrangement of 
 the nerves forming the brachial plexus. This arrangement is, however, very variable, 
 often differing on the two sides in the same subject, 
 
. fj j 
 
 e^f -i *i4u$tULu -t^e^t 
 
 232 DISSECTION OF THE UPPER ARM. 
 
 cutaneous, and the outer head of the median ; from the inner cord, 
 another anterior thoracic nerve, the inner head of the median, the 
 ulnar, the internal, and the lesser internal cutaneous. From the 
 posterior cord, the three subscapular nerves, the circumflex and 
 the musculo-spiral. 
 
 The anterior thoracic nerves have been described (p. 222). 
 Subscapular The three 'subscapular' nerves are found on the 
 nerves. surface of the subscapularis. They come from the 
 
 posterior cord of the brachial plexus, and supply respectively the 
 latissimus dorsi, teres major, and subscapularis. The nerve for 
 the latissimus dorsi (called the long subscapular nerve) runs with 
 the anterior branch of the subscapular artery. 
 
 The nerve for the teres major is either a branch of the preceding, 
 or comes distinct from the plexus. It lies nearer to the humerus 
 than the long subscapular, and after supplying a branch to the 
 latissimus dorsi, terminates in the teres major. 
 
 The proper nerve of tJie subscapularis arises from the plexus 
 higher than the others. 
 
 Circumflex The posterior circumflex artery is accompanied by 
 nerve. the circumflex nerve which supplies the deltoid. This 
 
 large nerve comes from the posterior part of the brachial plexus, 
 in common with the musculo-spiral and subscapular nerves, and, 
 after sending a branch to the teres minor, terminates in the under 
 surface of the deltoid. The nerve supplies the skin covering the 
 deltoid by branches which turn round the posterior border of the 
 muscle ; other branches are distributed to the skin over the long 
 head of the triceps. 
 
 DISSECTION OF THE UPPEB AEM. 
 
 Let the incision be continued down the inner side of the arm 
 as far as two inches below the elbow. Eeflect the skin, and trace 
 the following cutaneous nerves. 
 
 Cutaneous The filaments of the intercosto-humeral nerves run 
 
 nerves. down the inner and posterior part of the arm, to the 
 
DISSECTION OF THE UPPER ARM. 233 
 
 oleeranon; on the inner side of the arm, one joins a branch from 
 the nerve of Wrisberg. 
 
 The branches of the internal cutaneous nerve perforate the 
 fascia about the middle of the inner side of the arm, and subdivide 
 into filaments which supply the anterior and posterior surface of 
 the forearm, as low as the wrist. 
 
 The lesser internal cutaneous (nerve of Wrisberg) perforates 
 the fascia about the lower third of the arm, and supplies the skin 
 over the internal, condyle and oleeranon. 
 
 The internal cutaneous branch of the musculo-spiral nerve, 
 sometimes wanting, and always small, comes through the fascia 
 near the middle of the inner side of the arm. 
 
 The nerves which perforate the fascia near the middle of the 
 outer part of the arm, are the external cutaneous branches of the 
 musculo-spiral. They are accompanied by a small branch from 
 the superior profunda artery. They divide into filaments, one of 
 which is to be traced down the outer and back part of the forearm, 
 nearly as low as the wrist. 
 
 On the outer side of the tendon of the biceps the external cu- 
 taneous nerve perforates the fascia, and divides into many branches, 
 which supply the skin of the outer part of the forearm. 
 
 . . The next object of attention should be the disposition 
 
 of veins in of the veins in front of the elbow. In cleaning these 
 front of the veins, take care not to divide the branches of the in- 
 
 c*lbow 
 
 ternal and external cutaneous nerves which pass both 
 above and below them. 
 
 The following is the ordinary arrangement of the superficial 
 veins at the bend of the elbow : On the outer side is the radial ; on 
 the inner side is the ulnar vein ; in the centre is the median, 
 which divides into two branches ; the external of which, uniting 
 with the radial to form the cephalic vein, is called the median 
 cephalic ; the internal, uniting with the ulnar to form the basilic, 
 is named the median basilic. Near its bifurcation, the median 
 vein communicates by a branch (mediana profunda) with the deep 
 veins which accompany the arteries of the forearm. 
 
 Trace the cephalic vein up the arm. It runs along the outer 
 
234 
 
 DISSECTION OF THE UPPER ARM. 
 
 border of the biceps to the groove between the pectoralis major 
 and the deltoid, where it terminates in the axillary. 
 
 Fig. 49. 
 
 
 Median basilic v. 
 
 Deep median v. 
 
 SUPEBFICIAL VEINS AND NERVES AT THE BEND OF THE LEFT ELBOW. 
 
 The basilic vein ascends along the inner side Q the arm with 
 the internal cutaneous nerve. Near the upper third of the arm, 
 it perforates the fascia, and empties itself either into the internal 
 vena comes of the brachial artery, or into the axillary vein. 
 
 The principal branches of the nerves pass beneath 
 the veins ; but many small filaments cross in front 
 which are exposed to injury in venesection. 
 
 Since the median basilic vein is larger than the 
 median cephalic, and, on account of the strong fascia 
 beneath, more easily compressible, it is usually chosen 
 for venesection ; its position therefore, in reference to 
 the brachial artery, becomes very important. The 
 vein is only separated from the artery by the fascia, derived from 
 
 Relation of 
 nerves and 
 veins at 
 elbow. 
 
 Relation of 
 median 
 basilic vein 
 to brachial 
 artery. 
 
DISSECTION OF THE UPPER ARM. 235 
 
 the tendon of the biceps. This fascia is in some subjects remark- 
 ably thin, or even absent. It sometimes happens that the artery 
 lies above the fascia, in absolute contact with the vein. In 
 choosing, therefore, this vein for venesection, there is a risk of 
 wounding the artery; hence the practical rule, to bleed either 
 from the median cephalic, or from the median basilic above the 
 situation where it crosses the brachial artery. 
 
 Immediately above the internal condyle, in the neighbourhood 
 of the basilic vein, we find one or two small absorbent glands. 
 Others may be higher up along the inner side of the arm. I have 
 seen a gland at the bend of the elbow ; but never below this joint. 
 These little glands are the first which become tender and enlarged 
 after an injury to the hand. 
 
 Muscular The fascia which invests the muscles of the upper 
 
 fascia. arm is a continuation of the fascia from the trunk and 
 
 the axilla. This membrane varies in density ; thus it is thin over 
 the biceps, stronger on the inner side of the arm, to protect the 
 brachial vessels and nerves, and strongest over the triceps. What 
 are its connections ? At the upper part of the arm it is connected 
 with the coracoid process and the clavicle ; it is strengthened at 
 the axilla by an expansion from the tendons of the pectoralis 
 major and latissimus dorsi; posteriorly, it is attached to the spine 
 of the scapula. The fascia surrounds the brachial vessels with a 
 sheath, and furnishes partitions which separate the muscles from 
 each other. Of these partitions the most marked are the external 
 and internal intermuscular septa, which divide the muscles on 
 the anterior from that on the posterior surface of the upper arm. 
 These septa are attached to the condyloid ridges of the hum eras 
 and to the condyles. The internal septum, the stronger of the 
 two, begins at the insertion of the coraco-brachialis, and separates 
 the triceps extensor from the brachialis anticus. The external 
 septum commences from the insertion of the deltoid, and separates 
 the brachialis anticus, the supinator longus, and the extensor 
 carpi radialis longior in front, from the triceps behind. 
 
 At the lower part of the upper arm, the fascia is remarkably 
 strong, especially where it covers the brachialis anticus, and the 
 
236 DISSECTION OP THE UPPER ARM. 
 
 brachial vessels, and is continued over the muscles on the inner 
 side of the forearm. At the back of the elbow, the fascia is 
 attached to the tendon of the triceps, and the olecranon. 
 
 Now remove the fascia in order to study the muscles on the 
 front of the arm ; namely, the biceps, the coraco-brachialis, and 
 the brachialis anticus. 
 
 The biceps, as its name implies, arises by two heads 
 a long and a short. The short or internal head 
 arises from the point of the coracoid process of the scapula, by a 
 thick flat tendon which is common to a slender muscle on its 
 inner side, called the coraco-brachialis. The long head of the 
 biceps arises from the upper border of the glenoid cavity of the' 
 scapula by a long round tendon, which traverses the shoulder- 
 joint and passes over the head of the humerus, and down the 
 groove between the two tuberosities. The tendon is retained in 
 the groove by a fibrous bridge derived from the capsule of the 
 joint, and connected with the tendon of the pectoralis major. 
 Divide this bridge and see that the synovia! membrane of the 
 joint is reflected round the tendon, and accompanies it for about 
 two inches down the groove, thus forming a sort of synovial fold. 
 The object of this is to facilitate the play of the tendon, and to 
 carry little arteries (from the anterior circumflex) for its supply. 
 The two heads unite about the middle of the arm, and form a 
 single muscle, which terminates in a strong flat tendon of con- 
 siderable length ; this sinks deep into the triangular space at the 
 bend of the elbow, and, after a slight twist upon itself, is inserted 
 into the posterior part of the tubercle of the radius. The anterior 
 part of the tubercle, over which the tendon plays, is crusted with 
 cartilage, and a bursamucosa intervenes to prevent friction. The 
 most internal fibres of the muscle are inserted into a strong broad 
 aponeurosis, which is prolonged from the inner border of the 
 tendon to the fascia on the inner side of the forearm. This 
 aponeurosis, called the semi-lunar fascia of the biceps, protects 
 the brachial vessels and the median nerve at the bend of the 
 elbow. 
 
 The action of the biceps is twofold. 1. It is a flexor of the 
 
DISSECTION OF THE UPPER ARM. 237 
 
 forearm : 2. It is a supinator of the forearm, in consequence of its 
 insertion into the posterior part of the tubercle of the radius. Its 
 power of supination is greatest when the arm is bent, because its 
 tendon is then inserted at a right angle. Why does the long 
 tendon pass through the shoulder-joint? It acts like a strap, and 
 confines the head of the humerus in its proper centre of motion. 
 But for this tendon, the head of the bone, when the deltoid acts, 
 would be pulled directly upwards and strike against the under 
 surface of the acromion. When the tendon is ruptured or dislo- 
 cated from its groove a man can move his arm backwards and 
 forwards, but he cannot raise the smallest weight. The biceps is 
 supplied with blood by an artery (from the brachial), which runs 
 into the middle of it, and then divides into ascending and descend- 
 ing branches. Its nerve comes from the external cutaneous 
 (musculo cutaneous). 
 
 Coraco- This thin muscle is situated at the upper part of the 
 
 brachialis. armj an d runs parallel to the inner border of the short 
 head of the biceps. It arises by fleshy fibres from the point of 
 the coracoid process, in common with the short head of the biceps, 
 and from a fibrous septum which lies between them. The muscle 
 terminates in a flat tendon, which is inserted into the inner side 
 of the middle of the humerus, between the brachialis anticus and 
 the inner head of the triceps. Its action is to draw the humerus 
 forwards and inwards, e. g. in bringing the gun up to the shoulder. 
 
 Concerning the coraco-brachialis remember, 1. That the ex- 
 ternal cutaneous nerve runs through it ; 2. That its inner fleshy 
 border is the guide to the axillary artery in the last part of its 
 course ; 3. That the brachial artery lies upon its flat tendon of 
 insertion, and can here be effectually compressed by the finger or 
 the tourniquet. 
 
 The coraco-brachialis and biceps are covered at their upper 
 part by the deltoid and pectoralis major. The head of the 
 humerus rolls beneath the coraco-brachialis and short origin of 
 the biceps ; and a large bursa is interposed between these muscles 
 and the tendon of the subscapularis, which covers the head of 
 the bone. 
 
 
238 DISSECTION OF THE UPPER 
 
 Brachialis This muscle is situated close to the lower half of the 
 anticus. humerus, and is partially concealed by the biceps. 
 Between the two muscles you find the external cutaneous nerve, 
 which supplies them both. 
 
 It arises from the humerus by a fleshy digitation on either side 
 of the tendon of the deltoid ; from the front surface of the bone 
 below this point, and from the intermuscular septa. The muscle, 
 becoming thicker and broader as it descends, covers the front of 
 the capsule of the elbow-joint, and terminates in a tendon, which 
 is inserted in a pointed manner into the coronoid process of the 
 ulna. Its action is to bend the forearm. 
 
 Now examine the course and relations of the brachial vessels 
 and nerves. 
 
 The brachial artery, a continuation of the axillary, 
 relations of takes its name at the lower border of the teres major, 
 the brachial j^- runs d own the inner side of the arm, along the inner 
 
 artery. 
 
 border of the coraco-brachialis and biceps, to the front 
 of the elbow, where it divides, near the coronoid process of the 
 ulna, into the radial and ulnar arteries. 
 
 Thus its direction corresponds with a line drawn from the 
 anterior part of the axilla to the central point between the condyles 
 of the humerus. 
 
 In the upper part of its course it lies on the long and inner 
 heads of the triceps (from the long head it is separated by the 
 musculo-spiral nerve and superior profunda artery); in the middle, 
 it lies on the tendon of the coraco-brachialis ; in the lower part, 
 on the brachialis anticus. 
 
 The artery is accompanied by two veins (vence comites), and 
 the median nerve, all of which are invested in a common sheath 
 of fascia. The median nerve crosses obliquely in front of the 
 artery, lying, near the axilla, on its outer side, near the elbow on 
 its inner. 
 
 The ulnar nerve at first runs along the inner side of the artery, 
 but below is separated from it by the internal intermuscular 
 septum, where it passes behind the internal condyle. Superficial 
 to the artery, we find the internal cutaneous nerve and the basilic 
 vein. 
 
DISSECTION OF THE UPPER ARM. 239 
 
 Observe particularly that the artery is more or less overlapped, 
 in the first part of its course, by the coraco-brachialis, lower down 
 by the fleshy belly of the biceps ; these muscles in their respective 
 situations are the best guides to the artery. 
 
 About the middle of the humerus, the artery lies for nearly two 
 inches on the tendon of the coraco-brachialis, and is so close to 
 the bone that it can be effectually compressed ; here, too, it is 
 crossed by the median nerve. 
 
 At the bend of the elbow the artery is protected by the semi- 
 lunar fascia from the tendon of the biceps. It enters a triangular 
 space, bounded by the pronator radii teres internally, and by the 
 supinator radii longus externally. It sinks into this space, with 
 the tendon of the biceps to its outer side, and the median nerve 
 to its inner ; all three rest upon the brachialis anticus. Opposite 
 the coronoid process of the ulna it divides into the radial and 
 ulnar arteries. 
 
 Two veins, of which the internal is the larger, lie in close con- 
 tact with the brachial artery, and communicate at frequent inter- 
 vals by transverse branches. 
 
 Branches of ^^ e brachial artery gives off three branches, which 
 brachial arise from its inner side ; namely, the superior pro- 
 tery ' funda, the inferior profunda, and the anastomotica 
 
 magna. It also gives off muscular branches to the coraco-brachi- 
 alis and biceps. 
 
 The profunda superior arises from the brachial artery, immedi- 
 ately below the tendon of the teres major.* It winds round the 
 posterior part of the humerus, between the outer and inner heads 
 of the triceps, with the musculo-spiral nerve (p. 229), and a little 
 above the middle of the arm divides into two branches, which run 
 for some distance on either side of the nerve. One of these runs 
 in the substance of the triceps muscle to the olecranon, and anasto- 
 moses with the ulnar recurrent, the interosseous recurrent, and 
 anastomotica magna arteries ; the other branch accompanies the 
 
 * If you cannot find the profunda in its usual place, look for it above the tendon of 
 the latissimus dorsi, when you will probably find that it is given off from a common 
 trunk with the posterior circumflex. 
 
240 DISSECTION OF THE UPPER ARM. 
 
 musculo-spiral nerve to the outer side of the arm, descends deep 
 in the fissure between the brachialis anticus and supinator radii 
 longus, and terminates in numerous ramifications, some of which 
 pass in front of the external condyle, and others behind it, to 
 inosculate with the radial and interosseous recurrent arteries. 
 
 Fig. 50. 
 
 - 
 
 Superior prof unda .... ^B Inferior prof unda. 
 
 Anastomotica magna. 
 
 _ _ "Anterior ulnar recurrent. 
 
 Interosseous recurrent. . . 
 
 Posterior ulnar recurrent. 
 
 Eadial recurrent. . . . / 
 
 ^ \ ^^ Common interosseous. 
 
 Posterior interosseous . . . 
 
 "Anterior interosseous. 
 
 PLAN OF THE BRANCHES OF THE BEACHIAL ARTERY AND THE ARTKUIAL 
 INOSCULATIONS ABOUT THE RIGHT ELBOW-JOINT. 
 
 Before its division, the superior profunda sends several branches 
 to the triceps, some of which inosculate minutely with the circum- 
 flex arteries. These would assist in establishing a collateral 
 
DISSECTION OF THE UPPER ARM. 241 
 
 circulation if the brachial artery were tied above the origin of the 
 prof un da. 
 
 The profunda inferior arises from the brachial, opposite to the 
 insertion of the coraco-brachialis, or sometimes by a common 
 trunk with the superior profunda. It runs with the ulnar nerve 
 on the inner head of the triceps (which it supplies), to the interval 
 between the internal condyle and the olecranon, where it inoscu- 
 lates with the posterior ulnar recurrent and anastomotica magna 
 arteries. 
 
 The medullary artery of the humerus arises sometimes from 
 the brachial, sometimes from the inferior profunda. It pierces 
 the tendon of the coraco-brachialis, runs obliquely downwards 
 through the bone, and in the medullary canal divides into ascend- 
 ing and descending brandies, which anastomose with the nutrient 
 vessels of the bone derived from the periosteum. 
 
 The anastomotica magna arises from the inner side of the 
 brachial, about two inches above the elbow, runs tortuously in- 
 wards across the brachialis anticus, and divides into branches, 
 some of which pass in front of, others behind the internal condyle, 
 anastomosing with the superior ffrofunda, the inferior profunda, 
 and the anterior ulnar recurrent arteries. 
 
 Numerous unnamed muscular branches arise from the outer 
 side of the brachial artery ; one of these, more constant than the 
 rest, supplies the biceps; another runs transversely beneath the 
 coraco-brachialis and biceps, over the insertion of the deltoid, 
 supplying this muscle and the brachialis anticus. 
 Venae The two veins which accompany the brachial artery 
 
 comites. are continuations of the deep radial and ulnar veins. 
 The internal is usually the larger, since it generally receives the 
 veins corresponding to the principal branches of the artery. In 
 their course they are connected at intervals by transverse branches 
 either in front of, or behind the artery. Near the subscapularis, 
 the vena comes externa crosses obliquely in front of the axillary 
 artery to join the vena comites interna, which then takes the 
 name of ' axillary.' 
 
 Now trace the great nerves of the upper arm, which proceed 
 
 R 
 
242 DISSECTION OF THE UPPER ARM. 
 
 from the brachial plexus near the tendon of the subscarplaris ; 
 namely, the median, the external cutaneous, ulnar, and musculo- 
 spiral or radial. 
 
 Median The median nerve arises by two roots, which con- 
 
 nerve, verge in front of the axillary artery (p. 231). The 
 
 external root is derived from a trunk in common with the external 
 cutaneous ; the internal from a trunk in common with the ulnar 
 and internal cutaneous. In its course down the arm, the nerve is 
 situated at first on the outer side of the brachial artery, between 
 it and the coraco-brachialis ; about the middle of the arm the 
 nerve crosses obliquely over the vessel, or perhaps beneath it, so 
 that at the bend of the elbow it is found on the inner side of the 
 artery, lying upon the brachialis anticus, and covered by the 
 semilunar fascia from the biceps.* 
 
 The eventual distribution of the median nerve is to the two 
 
 * I have observed the following varieties relating to the median nerve, and its course 
 in regard to the artery: 
 
 a. The roots may be increased in number by one on either side of the artery ; or the 
 internal root may be deficient. 
 
 b. They may vary in their position with regard to the artery ; both may be situated 
 behind the vessel, or one behind, and the other in front of it. 
 
 c. The nerve, formed in the usual manner, may be joined lower down by a large 
 branch from the external cutaneous ; such a case presents a junction of two large 
 nerves in front of the brachial artery, in the middle of the arm. 
 
 d. The nerve in many cases crosses under, instead of over the artery. 
 
 e. The nerve sometimes runs parallel and external to the artery ; or it may run 
 parallel to, and in front of the artery. 
 
 In one hundred arms the relative position of the nerve to the artery in its course 
 down the arm was as follows : 
 
 In 72, the nerve took the ordinary course. 
 
 ,, 20, the nerve, crossed obliquely under the artery. 
 
 5, the nerve ran parallel and superficial to the artery. 
 
 3, the nerve ran parallel and external to the artery. 
 
 These varieties of the median nerve are of practical importance, for this reason : 
 whenever, in the operation of tying the brachial artery, we do not find the nerve in 
 its normal position, we may expect to find some irregular distribution of the arteries, 
 e.g. a high division of the brachial, or even, which I have often seen, a ' vas aberrans ' 
 coming from the upper part of the brachial, and joining either the radial or ulnar 
 arteries. 
 
DISSECTION OF THE UPPER ARM. 243 
 
 pronators and all the flexors of the forearm (except the flexor 
 carpi ulnaris and the ulnar half of the flexor profundus digitorum), 
 to the muscles of the ball of the thumb, to both sides of the 
 thumb, fore and middle fingers, and the radial side of the ring 
 finger. 
 
 E t nal This nerve (often called the musculo-cutaneous or 
 
 cutaneous ( perforans Casserii') arises in common with the ex- 
 ternal root of the median, from the external cord of 
 the brachial plexus, and is situated on the outer side of the axillary 
 artery. It perforates the coraco-brachialis, and then runs down 
 between the biceps and the brachialis anticus. A little above the 
 elbow-joint, between the tendon of the biceps and the supinator 
 radii longus, the nerve becomes subcutaneous, and, passing under 
 the median cephalic vein, divides into branches, for the supply of 
 the integuments of the forearm. 
 
 The external cutaneous nerve, in the upper part of its course, 
 sends branches to the coraco-brachialis and the short head of the 
 biceps, and, as it descends between the biceps and the brachialis 
 anticus, it supplies both. Consequently, if the nerve were divided 
 in the axilla, the result would be inability to bend the arm.* 
 This nerve also sends some small branches to supply the elbow- 
 joint. 
 
 This nerve arises from the inner cord of the brachial 
 
 Ulnar nerve. , . .,, ,, . , , , 
 
 plexus, in common with the internal cutaneous and 
 
 the inner head of the median. It descends along the inner side 
 of the brachial artery, as far as the insertion of the coraco-brachi- 
 alis. The nerve then diverges from the artery, perforates the 
 internal intermuscular septum, and runs with the inferior pro- 
 fun da artery, behind the internal condyle. 
 
 * In some instances the external cutaneous nerve descends on the inner side of the 
 coraco-brachialis without perforating the muscle ; in these cases it often sends a larger 
 branch than usual to the median nerve. 
 
 The trunk of the external cutaneous nerve may come from the median at any point 
 between the axilla and the middle of the arm. In some subjects the nerve is absent ; 
 all its branches are then supplied by the median, which is larger than usual. Such 
 anomalies are easily explained by the fact of the two nerves having always a common 
 origin. 
 
 Bfl 
 
244 DISSECTION OF THE UPPER ARM.-. 
 
 The eventual distribution of the nerve is to the flexor carpi 
 ulnaris, half the flexor profundus digitorum, all the interosseous 
 muscles of the hand, both sides of the little finger, and the ulnar 
 side of the ring finger ; also to the muscles of the ball of the little 
 finger. 
 
 Previous to the examination of the musculo-spiral nerve, we 
 should have some knowledge of the great muscle which occupies 
 the whole of the posterior part of the humerus viz., the triceps. 
 Tricfi This muscle has three distinct origins, named from 
 
 extensor their position, external, internal, and middle or long 
 cubiti. k ea( j ^ 229). The middle or long head arises by a 
 
 flat tendon from the inferior border of the scapula, close to the 
 glenoid cavity. The external head arises from the humerus 
 immediately below the insertion of the feres minor. The internal 
 head arises from the humerus below the insertion of the teres 
 major. The three heads unite near the middle of the arm to 
 form a single fleshy mass, which covers the posterior part of the 
 elbow-joint, and is inserted by a thick tendon into the summit 
 and sides of the olecranon. 
 
 Mu This, the largest of the brachial nerves, arises, in 
 
 spiral or common with the circumflex, from the posterior cord 
 radial nerve. of the ax in aiy pl exu s (p. 231). It descends at first 
 behind the axillary artery, and then winds obliquely round the 
 posterior part of the humerus, between the external and internal 
 heads of the triceps, in company with the superior profunda 
 artery. About the lower third of the outer side of the arm, the 
 nerve runs deeply imbedded between the brachialis anticus and 
 the supinator radii longus. A little above the elbow-joint it 
 divides into its two principal branches the radial, which accom- 
 panies the radial artery along the forearm and the posterior 
 interosseous, which perforates the supinator brevis, and supplies all 
 the muscles on the back of the forearm. 
 
 What is the distribution of this great nerve ? In a word, it 
 supplies all the extensors of the forearm, wrist, thumb, and fingers ; 
 and all the supinators except one, namely, the biceps (supplied by 
 the external cutaneous nerve). 
 
DISSECTION OF THE FRONT OF THE FOREARM. 245 
 
 DISSECTION OF THE FEONT OF THE FOEEAEM. 
 
 Prolong the incision down to the wrist, and at its termination 
 make another transversely. Eeflect the skin, and carefully dissect 
 the subcutaneous veins and nerves. 
 
 On the inner side is found the anterior ulnar vein, 
 which commences on the front of the little linger and 
 wrist, and is then continued upwards on the inner side 
 of the forearm as far as the elbow, where it is joined by the 
 posterior ulnar vein to form the basilic (p. 234). 
 
 The veins on the back of the hand commence at the extremities 
 of the fingers, run up betiveen the knuckles, and unite on the 
 back of the hand in the shape of an arch, with its concavity up- 
 wards. The posterior ulnar vein arises from this arch by a branch 
 (vena salvatella) situated over the fourth interosseous space, and 
 runs up on the back of the forearm towards the inner condyle, to 
 join the anterior ulnar vein. 
 
 The radial vein, situated on the outer side of the forearm, 
 commences on the back of the hand from the venous arch, runs 
 up the outer side of the front of the forearm to the elbow, where 
 it becomes the cephalic. 
 
 Eunning up in front of the middle of the forearm is the median 
 veini near the bend of the elbow it is joined by a deep branch 
 mediana profunda after which it divides into two branches, an 
 outer or median cephalic, which joins the cephalic, and an inner or 
 median basilic, which joins the basilic. 
 
 On the radial side of the forearm, as low down as 
 the wrist, are found the terminal branches of the 
 musculo-cutaneous nerve. At the lower part of the 
 forearm, these filaments are situated over the radial artery. On 
 the ulnar side is the anterior division of the internal cutaneous 
 nerve, while its posterior branch passes to the back of the forearm, 
 supplying it as far as the middle. On the outer and back part of 
 the forearm near the elbow, the external cutaneous branch of the. 
 musculo-spiral is seen running down as far as the wrist. At the 
 lower third of the radial side of the forearm, the radial nerve 
 
246 DISSECTION OF THE FRONT OF THE FOREARM. 
 
 becomes superficial, and turns over the radius to supply the back of 
 the hand and fingers. Near the styloid process of the ulna, the 
 dorsal branch of the ulnar nerve perforates the fascia to reach the 
 back of the hand. 
 
 The muscles of the forearm are enveloped by a dense 
 Deep fascia shining aponeurosis, which is continuous with that of 
 
 of the fore- ,. T . .. . , ., , 
 
 arm> the upper arm. Its thickness increases as it approaches 
 
 the wrist, in order that the tendons in this situation 
 may be effectually maintained in their position. It is composed 
 of fibres which cross each other obliquely, and is attached above 
 to the condyles of the humerus and olecranon ; internally, to the 
 ridge on the posterior part of the ulna. At the back of the 
 wrist it forms the posterior annular ligament, and in front is 
 continuous with the anterior annular ligament. Above, the fascia 
 is strengthened by fibres from the tendons of the biceps and 
 brachialis anticus. The aponeurotic expansion from the inner 
 edge of the tendon of the biceps is exceedingly strong. It braces 
 the muscles on the inner side of the forearm, and interlaces at 
 right angles with the fibres of the fascia attached to the internal 
 condyle. The under surface of the fascia gives origin to the 
 muscular fibres in the upper part of the forearm, and furnishes 
 septa which separate the muscles, and form so many distinct 
 sheaths for them. The fascia is perforated at various parts for the 
 passage of the cutaneous vessels and nerves of the forearm. 
 
 Eemove the fascia from the muscles by incisions corresponding 
 to those for reflecting the skin ; taking care of the cutaneous 
 branches of the median and ulnar nerves close to the wrist. 
 
 At the bend of the elbow, a triangular space is found, with its 
 base towards the humerus ; on the inner side it is bounded by 
 the pronator teres ; on the outer, by the supinator radii longus. 
 In it are found the following objects, which must be carefully 
 dissected: 1. The brachial artery (with its companion veins) 
 dividing into the radial and ulnar ; 2, on the outer side of the 
 artery is the tendon of the biceps ; 3, on the inner, the median 
 nerve; 4, the musculo-spiral nerve, partly concealed by the 
 supinator longus ; 5, the radial recurrent artery ; 6, the anterior 
 
DISSECTION OF THE FRONT OF THE FOREARM. 247 
 
 ulnar recurrent ; 7, the common interosseous branch of the ulnar 
 artery. 
 
 The muscles of the forearm are arranged in two 
 
 Muscles of . , . r. j 
 
 forearm groups ; one, consisting ot supmators and extensors, 
 is attached to the outer condyloid ridge and condyle ; 
 the other, consisting of pronators and flexors, is attached to the 
 inner condyle. The inner group should be examined first : they 
 arise by a common tendon, and are arranged in the following 
 order : pronator teres ; flexor carpi radialis ; palmaris longus ; 
 flexor carpi ulnaris, and flexor sublirnis digitorum. 
 
 This muscle forms the inner boundary of the tri- 
 radiHeres an g u ^ ar space at the elbow. It arises from the 
 anterior surface of the internal condyle, from the 
 common tendon, and from the septum between it and the flexor 
 carpi radialis. It has also a small tendinous origin from the 
 coronoid process of the ulna. From these two origins, between 
 which the median nerve passes, the muscle proceeds obliquely 
 downwards, and is inserted by a flat tendon into a rough surface 
 on the outer and back part of the middle third of the radius. In 
 amputating the forearm, it is very desirable to save the insertion 
 of this muscle, that the stump may have a pronator. 
 
 This muscle arises by the common tendon from the 
 i n t erna l condyle, from the intermuscular septa, and 
 from the fascia of the forearm. The fleshy fibres 
 terminate near the middle of the forearm, in a flat tendon, which 
 runs in a separate sheath outside the anterior annular ligament of 
 the wrist, passes through a groove in the os trapezium, lined by a 
 synovial membrane, and is inserted into the bases of the second 
 and third metacarpal bones. Note that the outer border of its 
 tendon is the guide to the radial artery in the lower half of the 
 forearm. 
 
 This slender muscle arises from the common tendon 
 
 longus. a ^ the internal condyle, from the intermuscular septa, 
 
 and from the fascia of the forearm. About the middle 
 
 of the forearm it terminates in a flat tendon, which descends 
 
 vertically down the middle of the forearm to the wrist, lying upon 
 
248 DISSECTION OF THE FRONT OF THE FOREARM. 
 
 the flexor sublimis digitorum ; it then passes over the anterior 
 annular ligament, and is continued into the palmar fascia. This 
 muscle is a tensor of the palmar fascia. * i*$rr~ 
 
 This muscle arises by tflP> heacls; one from the 
 internal condyle, the common tendon, and the inter- 
 muscular septum ; . tfife '* o\her from the inner edge of 
 the olecranon : these two origins form an arch under which the 
 ulnar nerve passes. It also arises from the upper two-thirds of 
 the posterior edge of the ulna, through the medium of the aponeu- 
 rosis, which is common to this muscle and the flexor profundus 
 digitorum. The tendon appears on the radial side of the muscle, 
 about the lower third of the forearm, and receives fleshy fibres on 
 its ulnar side as low as the wrist. It is inserted into the os pisi~ 
 forme, and thence by a strong tendon into the os unciforme and 
 the base of the fifth rnetacarpal bone. 
 
 The tendon of the flexor carpi ulnaris is the guide to the ulnar 
 artery, which lies close to its radial side, and is overlapped by it. 
 As it passes over the annular ligament, the tendon furnishes a 
 fibrous expansion to protect the ulnar artery and nerve. 
 -p le This muscle is situated beneath those previously tnen- 
 
 sublimis digi- tioned, and has two distinct origins. The longer origin 
 takes place from the internal condyle, from the internal 
 lateral ligament, the common tendon, the intermuscular septa, 
 and the coronoid process of the ulna ; the shorter origin takes place 
 by tendinous and fleshy fibres from an oblique ridge on the front 
 of the radius, extending to about an inch below the insertion of 
 the pronator teres. This, called its radial origin, is partly con- 
 cealed by the pronator teres. The muscle thus formed passes down 
 the middle of the forearm, and divides into four distinct muscular 
 slips : from these, four tendons arise, which pass beneath the annu- 
 lar ligament into the palm, and on to the fingers, where they split 
 to allow the passage of the deep flexor tendons, and are inserted 
 
 * The palmaris longus is sometimes absent. The situation of its muscular portion is 
 subject to variety ; sometimes occupying the middle, sometimes the lower third of the 
 forearm. The tendon is in some instances wholly inserted into the anterior annular 
 ligament, 
 
DISSECTION OF THE FRONT OF THE FOREARM. 249 
 
 into the sides of the second phalanges. Its action is, therefore, to 
 bend the second joint of the fingers. 
 
 Having finished the superficial muscles on the inner side of the 
 forearm, notice one of those on the outer side, named supinator 
 radii longus, before you trace the vessels and nerves of the fore- 
 arm. 
 
 Su inator ^^ muscle forms the external boundary of the 
 
 radii longus. triangular space at the bend of the elbow. It arises 
 from the upper two-thirds of the external condyloid 
 ridge of the humerus, commencing a little below the insertion of 
 the deltoid. The muscular fibres terminate about the middle of 
 the forearm in a flat tendon, which is inserted into the base of the 
 stvloid process of the radius. The inner border of the muscle is 
 the guide to the radial artery. It supinates the hand, but acts 
 much more powerfully as a flexor of the forearm. 
 
 The radial artery, one of the divisions of the brachial, 
 ery 'runs down the radial side of the forearm to the wrist, 
 where it turns over the external lateral ligament of the carpus, 
 beneath the extensor tendons of the thumb, and sinks into the 
 space between the first and second metacarpal bones to form the 
 deep palmar arch. Thus, a line drawn from the middle of the 
 bend of the elbow to the front of the styloid process of the radius 
 indicates its course. In the upper third of the forearm, the artery 
 lies between the pronator teres on the inner, and the supinator 
 longus on the outer side ; the fleshy border of the latter overlaps 
 it in muscular subjects. In the lower two-thirds of the forearm 
 the artery is more superficial, and is placed between the tendons 
 of the supinator longus on the outer, and the flexor carpi radialis 
 on the inner side. In its course, it lies successively on the follow- 
 ing : first upon the tendon of the biceps ; secondly, upon the 
 supinator radii brevis ; thirdly, upon the tendon of the pronator 
 teres ; fourthly, upon the radial origin of the flexor sublimis ; 
 fifthly, upon the flexor longus pollicis ; sixthly, upon the pronator 
 quadratus ; and, lastly, upon the radius. It is accompanied by 
 two veins, which communicate at frequent intervals, and join the 
 ven^e comites of the brachial artery at the bend of the elbow. 
 
250 DISSECTION OF THE FRONT OF THE FOREARM. 
 
 In the middle third of its course the artery is accompanied by 
 the radial nerve (a branch of the musculo-spiral) which lies to its 
 outer side. Below this point, the nerve leaves the artery, and 
 passes under the tendon of the supinator longus to the back of the 
 hand. 
 
 Thus, in the situation where the pulse is felt, the radial nerve 
 no longer accompanies the artery ; nevertheless, the vessel is not 
 without a nerve, for it is accompanied by a branch of the musculo- 
 cutaneous (or external cutaneous), which runs superficial to it. 
 
 The radial artery sends off in the forearm the following branches, 
 besides offsets, which supply the muscles on the outer side of the 
 forearm. 
 
 The radial recurrent is given off just below the elbow ; it 
 passes outwards to supply the long and short supinators and the 
 two radial extensors. One of its ramifications runs up with the 
 musculo-spiral nerve between the supinator longus and brachialis 
 anticus, and forms a delicate inosculation with the superior 
 profunda (p. 240). 
 
 The arteria superficialis voice arises from the radial, about half 
 an inch, or more, above the lower end of the radius ; it runs 
 superficially over the anterior annular ligament, above or perhaps 
 through the origin of the muscles of the ball of the thumb, into 
 the palm of the hand, where it inosculates with the superficial 
 branch of the ulnar, and completes the superficial palmar arch.* 
 
 The anterior and posterior carpal arteries are small branches 
 of the radial, which run beneath the tendons, and supply the 
 synovial membrane and bones of the carpus, anastomosing with 
 the anterior interosseous, the carpal branches of the ulnar, and the 
 recurrent carpal branch of the deep palmar arch. 
 
 Eadial nerve Tlie ra ^ ia ^ nerve > a branch of the musculo-spiral, is 
 
 given off above the bend of the elbow, deep between 
 
 the supinator radii longus and brachialis anticus ; it descends on 
 
 * There is great variety in the size and origin of the superficialis volge ; sometimes 
 it is very large, arises higher than usual, and runs to the wrist parallel with the 
 radial ; sometimes it is very small, terminating in the muscles of the thumb ; or it may 
 be absent. 
 
DISSECTION OF THE FRONT OF THE FOREARM. 251 
 
 the outer side of the radial artery, covered by the supinator radii 
 longus. In the upper third of the forearm the nerve is at some 
 distance from the artery ; in the middle third it approaches nearer 
 to it ; but in the lower third, the nerve leaves the artery, passes 
 underneath the tendon of the supinator longus, perforates the fascia 
 on the outer side of the forearm, and divides into two branches, 
 which supply the back of the thumb, fore, and half the middle 
 finger. 
 
 This artery, the larger of the two divisions of the 
 ery ' brachial, comes off at the middle of the elbow, runs 
 obliquely inwards along the ulnar side of the forearm to the wrist, 
 passes over the annular ligament near the pisiform bone, and 
 entering the palm, forms the superficial palmar arch, by inoscu- 
 lating with the superficialis volse. 
 
 In the upper half of its course the artery describes a gentle 
 curve with the concavity towards the radius, and lies deep beneath 
 the superficial layer of muscles, the pronator teres, flexor carpi 
 radialis, palmaris longus, and flexor sublimis digitorum. It is 
 also crossed in its upper part by the median nerve. In the 
 lower part of its course it descends between the flexor sub- 
 limis and flexor carpi ulnaris, of which the tendon partially 
 overlaps it at the wrist. The artery lies for a short distance on 
 the brachialis anticus ; in the remainder of its course it lies on the 
 flexor profimdus digitorum. 
 
 The ulnar nerve is at first separated from the artery by a consi- 
 derable interval : but about the middle of the forearm it joins the 
 artery, and accompanies it in the rest of its course, lying close to 
 its inner side. Both pass over the anterior annular ligament of 
 the carpus, lying close to the pisiform bone, the nerve being 
 nearer to the bone. A strong expansion from the tendon of the 
 flexor carpi ulnaris protects them in this exposed situation. 
 
 Observe particularly the depth of the ulnar artery under the 
 many muscles which cover it in the upper third of its course. In 
 the middle third it is partially overlapped by the flexor carpi 
 ulnaris. In the lower third it lies under the radial border of the 
 flexor carpi ulnaris, which is the proper guide to the vessel. The 
 
252 DISSECTION OF THE FRONT OF THE FOREARM. 
 
 artery is accompanied by two veins which join the venae comites of 
 the brachial. 
 
 The ulnar artery furnishes the following branches in the fore- 
 arm : 
 
 The anterior and posterior ulnar recurrent arise immediately 
 below the elbow-joint, sometimes by a common trunk. The 
 anterior passes upward between the brachialis anticus and the 
 pronator teres, and inosculates with the inferior profunda and 
 anastomotica magna. The posterior ascends between the flexor 
 sublimis and the flexor profundus digitorum, to the space between 
 the internal condyle and the olecranon : it then passes up between 
 the two heads of the flexor carpi ulnaris, where it inosculates with 
 the same arteries as the anterior (p. 240). 
 
 The common interosseous artery arises from the ulnar, about 
 an inch and a half below the division of the brachial ; and soon 
 divides into the anterior and posterior interosseous, which we shall 
 examine presently. 
 
 The anterior and posterior carpal branches communicate with 
 corresponding branches from the radial, and supply the synovia! 
 membrane and bones of the carpus. 
 
 This nerve runs behind the internal condyle, between 
 the two origins of the flexor carpi ulnaris. In its course 
 down the upper part of the forearm, the nerve is still covered by 
 this muscle, and lies upon the flexor profundus digitorum. About 
 the middle third of the forearm, the nerve joins the ulnar artery, 
 and runs along its inner side over the annular ligament into the 
 palm. 
 
 The ulnar nerve gives off some filaments which are distributed 
 to the elbow-joint, and supplies two muscles in the forearm ; 
 namely, the flexor carpi ulnaris and the inner half of the flexor 
 profundus digitorum. 
 
 About one inch and a half above the styloid process of the ulna, 
 the nerve gives off a large cutaneous branch to the back of the 
 hand. It crosses under the tendon of the flexor carpi ulnaris, and, 
 immediately below the styloid process of the ulna, appears on the 
 back of the hand, where it divides into branches, which supply the 
 
DISSECTION OF THE FRONT OF THE FOREARM. 253 
 
 back of the little finger, the ring, and half the middle finger ; here 
 also it sends a branch which communicates with the radial nerve. 
 
 This nerve, at the bend of the elbow, lies on the 
 nerve. inner side of the brachial artery. It then passes be- 
 
 tween the two origins of the pronator teres, and de- 
 scends along the middle of the forearm, between the flexor subliniis 
 and the flexor profundus digitorum. At the lower part of the fore- 
 arm it becomes more superficial, lying about the middle of the 
 wrist, between the outer tendon of the flexor sublirnis, and the inner 
 border of the tendon of the flexor carpi radialis : it then enters 
 'the palm beneath the anterior annular ligament, and divides into 
 five branches for the supply of the thumb, both sides of the fore 
 and middle fingers, and the outer side of the ring finger.* 
 
 Immediately below the elbow, the median nerve sends branches 
 to the pronator teres and all the flexor muscles of the forearm^ 
 except the flexor carpi ulnaris and the inner half of the flexor 
 profundus, which are supplied by the ulnar. The interosseous 
 branch of the median runs with the anterior interosseous artery, 
 upon the interosseous membrane between the flexor longus pollicis 
 and flexor profundus digitorum : it supplies both these muscles 
 and the pronator quadratus. 
 
 Before the median nerve passes beneath the annular ligament, it 
 sends off its superficial palmar branch, which passes over the 
 ligament, and divides into small filaments to supply the skin of the 
 palm and ball of the thumb. 
 
 Now reflect the superficial layer of muscles, to see those more 
 deeply seated. Preserve the principal vessels and nerves. 
 
 The deep-seated muscles are the flexor digitorum profundus, 
 and the flexor longus pollicis ; beneath both, near the wrist, lies 
 the pronator quadratus. Close to the interosseous membrane run 
 the anterior interosseous artery and nerve. 
 
 This is the thickest muscle of the forearm. It arises 
 
 .Plexor pro- 
 
 fundus from the upper two-thirds of the anterior surface of the 
 
 digitorum. ulQa ^ from ^ game exten t O f jft s internal surface, from 
 
 * If the tendon of the palmaris longus happen to be broader than usual, it may 
 partially cover the median nerve near the wrist ; but most frequently the nerve is im- 
 mediately beneath the fascia, the tendon lying to its ulnar side. 
 
254 DISSECTION OF THE FRONT OF THE FOREARM. 
 
 the aponeurosis attached to the posterior edge of the ulna, and 
 from the inner two-thirds of the interosseous ligament. About 
 the middle of the forearm it divides into four muscular slips, which 
 terminate in flat tendons. These tendons lie upon the same plane, 
 and pass beneath the annular ligament under those of the super- 
 ficial flexor, into the palm. On the first phalanx of the fingers, 
 the tendons of the deep flexor perforate those of the superficial, 
 and are inserted into the base of the third or ungual phalanx, 
 .p. This muscle is situated on the front surface of the 
 
 longus radius, outside the preceding. It arises from the front 
 
 polhcis. surface of the radius, between the tubercle and the 
 pronator quadratus, and from the interosseous membrane.* Its 
 tendon proceeds beneath the annular ligament to the last phalanx 
 of the thumb. 
 
 Pronator This square muscle arises from the lower fourth of the 
 
 quadratus. ulna ; its fibres pass transversely outwards, and are 
 inserted into the lower fourth of the radius. It rotates the radius 
 on the ulna. 
 
 Interosseous Nearly on a level with the insertion of the biceps, the 
 artery. ulnar artery gives off from its outer side the common 
 
 interosseous 9 which runs backwards for about half an inch, and 
 divides into the anterior and posterior interosseous. 
 
 The anterior interosseous artery runs down close to the inter- 
 osseous membrane, lying between the flexor profundus digitorum 
 and flexor longus pollicis. At the upper edge of the pronator 
 quadratus it divides into two branches ; one of which, the smaller, 
 passes behind the muscle, supplies it and the front of the carpal 
 bones, communicating with the anterior carpal arteries from the 
 radial and ulnar; the other, the most important, perforates the 
 interosseous membrane, and helps to supply the muscles on the 
 back of the forearm. 
 
 A branch, the arteria comes nervi mediani, which almost always 
 accompanies the median nerve, is an offset from the anterior inter- 
 osseous. It lies in close contact with the nerve, sometimes in its 
 
 * Sometimes by a slip from the coronoid process. 
 
DISSECTION OF THE PALM OF THE HAND. 255 
 
 very centre ; though usually of small size, it may be as large as 
 the ulnar artery itself, and in such cases passes under the annular 
 ligament with the nerve to join the palmar arch. This is interest- 
 ing, because it helps to explain the recurrence of haemorrhage from 
 a wound in the palm, even after the radial and ulnar arteries have 
 been tied. 
 
 The anterior interosseous artery also gives off branches to the 
 muscles on either side, and the nutrient arteries, which enter the 
 radius and ulna from below upwards, near the centre of the fore- 
 arm, to supply the medullary membrane. 
 
 . . . This nerve is a branch of the median ; it is close to 
 
 interosseous the artery, supplies the flexor longus pollicis, half the 
 nerve. flexor profundus digitorum, and the pronator quadratus. 
 
 DISSECTION OF THE PALM OF THE HAND. 
 
 Make a vertical incision along the centre of the palm, and a 
 transverse one along the bases of the fingers ; from this transverse 
 cut continue vertical incisions along the front of the fingers, and 
 reflect the skin ; taking care not to remove a small cutaneous 
 muscle the palmaris brevis situated near the ball of the little 
 finger, and also two small cutaneous branches of the median and 
 ulnar nerves, which are found in the fat of the palm. 
 
 Observe how closely, in the centre of the palm, the skin, adheres 
 to the palmar fascia beneath it. On the ball of the little finger 
 and the distal ends of the metacarpal bones, the subcutaneous 
 structure is composed of a dense filamentous tissue, which con- 
 tains numerous pellets of fat, forming a kind of elastic pad. A 
 similar padding protects the palmar surfaces of the fingers. These 
 cushions on the ends of the fingers defend them in the powerful 
 actions of the hand ; they are also useful in subservience to the 
 nerves of touch. 
 
 The palm is supplied with nerves by two small branches one, 
 the palmar branch of the median, passes in front of the anterior 
 annular ligament to the centre of the palm ; the other, a branch 
 of the ulnar, supplies the inner aspect of the hand. 
 
256 DISSECTION or THE PALM OF THE HAND; 
 
 This small cutaneous muscle is situated on the inner 
 
 Palmaris gj^ o f fog palm. It arises from the inner edge of the 
 central palmar fascia, and terminates in the skin on the 
 inner side of the palm. Its use is to support the pad on the inner 
 edge of the palm : it acts powerfully as we grasp ; it raises the 
 edge of the palm and hollows it, forming the ' cup of Diogenes.' 
 It is supplied by the ulnar nerve. 
 
 This fascia has a silvery lustre, and, in the centre of 
 Palmar the palm, is remarkably dense and strong. It is divided 
 into three portions, a central by far the strongest ; an 
 external, covering the muscles of the thumb; and an internal, 
 covering the muscles of the little finger. From the deep surface 
 of the fascia two septa dip down, so as to divide the palm into 
 three separate compartments ; one for the ball of the thumb, a 
 second for that of the little finger, and a third for the centre of the 
 palm. 
 
 The fascia is formed by a prolongation from the anterior annular 
 ligament. It is also strengthened by the expanded tendon of the 
 palmaris longus. 
 
 The central portion of the fascia is triangular, with the apex at 
 the wrist. About the middle of the palm it splits into four portions, 
 which are connected by transverse tendinous fibres, extending com- 
 pletely across the palm, and corresponding pretty nearly to the 
 transverse furrow of the skin in this situation. 
 
 Examine any one of these four portions of the fascia, and you 
 will find that it splits into two strips which embrace the corre- 
 sponding flexor tendons, and are intimately connected with the 
 transverse metacarpal ligament. The effect of this is that the 
 flexor tendons of each finger are kept in place in the palm, by a 
 fibrous ring. Between the four divisions of the palmar fascia the 
 digital vessels and nerves emerge, and descend in a line with the 
 clefts between the fingers. 
 
 In the hands of mechanics, in whom the palmar fascia is usually 
 very strong, we find that slips of it are lost in the skin at the 
 lower part of the palm, and also for a short distance along the 
 sides of the fingers. 
 
DISSECTION OF THE PALM OF THE HAND. 257 
 
 The chief use of the palmar fascia is to protect the vessels and 
 nerves from pressure when anything is grasped in the hand. It 
 also confines the flexor tendons in their proper place. 
 
 Between the interdigital folds of the skin, we find aponeurotic 
 fibres to strengthen them, constituting what are called the trans- 
 verse ligaments of the fingers. They form a continuous ligament 
 across the lower part of the palm, in front of the digital vessels 
 and nerves. 
 
 Cut through the palmar fascia at its attachment to the anterior 
 annular ligament, and reflect it towards the fingers, to expose the 
 vessels, nerves, and tendons in the palm. The vessels lie above 
 the nerves, and the tendons still deeper. There is an abundance 
 of loose cellular tissue to allow the free play of the tendons. 
 When suppuration takes place in the palm, it is seated in this 
 tissue. Reflect for a moment, what mischief is likely to ensue. 
 The matter cannot get to the surface through the dense palmar 
 fascia, or on the back of the hand ; it will therefore run up under 
 the annular ligament, and make its way deep amongst the tendons 
 of the forearm. 
 
 The ulnar artery, having passed over the annular liga- 
 nalmararch. men t near the pisiform bone, describes a curve across 
 the upper part of the palm beneath the palmar fascia 
 towards the thumb, and, gradually diminishing in size, inosculates 
 with the superficialis volse, and very commonly with a branch 
 from the arteria radialis iridicis, to form the superficial palmar 
 arch. The curve of the arch is directed towards the ball of the 
 thumb. How are we to ascertain its exact position in the hand ? 
 Most commonly its greatest convexity descends as low as a hori- 
 zontal line drawn across the junction of the upper with the middle 
 third of the palm. 
 
 In its passage over the annular ligament, the artery is protected 
 in a furrow, between the pisiform and unciform bones, and by an 
 expansion from the tendon of the flexor carpi ulnaris to the pal- 
 maris longus. The ulnar nerve lies close to its inner side. In 
 the palm, the artery rests for a short distance upon the muscles of 
 the little finger, then it lies upon the superficial flexor tendons 
 
 s 
 
258 
 
 DISSECTION OF THE PALM OF THE HAND. 
 
 and the divisions of the ulnar and median nerves ; and is covered 
 by the palmaris longus and the palmar fascia. 
 
 Fig. 51. 
 
 Badial artery 
 
 Buperficialis volae 
 
 Arteriamagna 
 pollicis . . 
 
 Eadialis indicis . 
 
 Ulnar artery. 
 
 Ulnaris profunda. 
 
 DIAGBAM OF THE SUPEBFICIAL AND DEEP PALMAR ABCHES. 
 
 1, 2, 3, 4. Interosseous branches. 
 
 Immediately below the pisiform bone, the ulnar 
 unar artery gives off the ulnaris profunda, which sinks 
 artery in the d ee ply into the palm between the abductor and flexor 
 palm * brevis minimi digiti, to assist in forming the deep pal- 
 
 mar arch. It is accompanied by the deep branch of the ulnar nerve. 
 
DISSECTION OF THE PALM OF THE HAND. 259 
 
 From the concavity of the arch small branches ascend to the 
 carpus, and inosculate with the other carpal branches of the radial 
 and ulnar arteries. 
 
 From the convexity of the arch arise four digital arteries, which 
 supply all the fingers, excepting the radial side of the index finger. 
 Observe carefully the course of these arteries, because you may 
 have to open abscesses in the palm. The first descends over the 
 muscles on the inner side of the palm, to the ulnar side of the 
 little finger, along which it runs to the apex. The second, third, 
 and fourth descend nearly vertically between the tendons, in a line 
 ivith the clefts between the fingers, and about half an inch above 
 the clefts each divides into two branches, which proceed along the 
 opposite sides of the fingers nearly to the end of the last phalanges, 
 where they unite to form an arch with the convexity towards the 
 end of the finger ; from this arch numerous branches supply the 
 papillae of the skin. 
 
 In the palm of the hand the digital arteries before they divide 
 are joined by a small branch from the corresponding interosseous 
 artery (a branch of the deep palmar arch). 
 
 The digital arteries freely communicate, on the palmar and dorsal 
 aspect of the fingers, by transverse branches, which supply the 
 joints and the sheaths of the tendons. Near the ungual phalanx, 
 a considerable branch passes to the back of the finger, and forms a 
 network of vessels round the root of the nail. 
 
 The ulnar nerve passes over the annular ligament 
 Ulnar nerve ^ o ^ palm, on the inner side of the ulnar artery, and 
 
 in the palm. r ' . 
 
 a little behind it. It lies in a groove between the pisi- 
 form and unciform bones, so that it is perfectly secure from pres- 
 sure in this apparently exposed situation. Immediately below the 
 pisiform bone, the nerve divides into a superficial and a deep 
 palmar branch. The deep branch supplies the muscles of the 
 little finger, and accompanies the ulnaris profunda artery into the 
 palm, to supply all the interosseous muscles, and the two inner 
 lumbricales. The superficial branch sends filaments to the pal- 
 maris brevis, to the integument on the inner side of the palm, and 
 then divides into two digital nerves, one for the supply of the 
 
 s 2 
 
260 DISSECTION OF THE PALM OF THE HAND. 
 
 ulnar side of the little finger, and the other for the contiguous 
 sides of the little and ring fingers. 
 
 The digital branches run along the sides of the fingers to their 
 extremities superficial to their corresponding arteries. The more 
 external of the two branches communicates with the median nerve 
 behind the superficial palmar arch. 
 
 This exceedingly strong and thick ligament confines 
 annular the flexor tendons of the fingers and thumb, and fastens 
 ligament of together the bones of the carpus. It is attached exter- 
 
 tne carpus. 
 
 nally to the scaphoid and trapezium ; internally to the 
 
 pisiform and unciform. Its upper border is continuous with the 
 aponeurosis in front of the wrist ; its lower terminates in the 
 palmar fascia ; its anterior surface receives the expanded tendon 
 of the palmaris longus, and gives origin to most of the muscles 
 constituting the ball of the thumb and little finger. 
 
 Cut vertically through the ligament, and observe, that, with the 
 carpal bones, it forms an elliptical canal, with the broad diameter 
 transversely. This canal is lined by a synovial membrane which 
 is reflected loosely over the tendons. Superficial to the ligament, 
 pass the palmaris longus, the ulnar artery and nerve, and the 
 palmar branch of the median nerve ; beneath it, pass the super- 
 ficial and deep flexor tendons of the fingers, the long flexor tendon 
 of the thumb, and the median nerve. The tendon of the flexor 
 carpi radialis does not run with the other tendons, but is con- 
 tained in a distinct sheath, lined by a separate synovial membrane, 
 formed partly by the annular ligament and partly by the groove 
 in the trapezium. 
 
 In its passage under the annular ligament, the 
 median nerve is enveloped in a fold of synovial mem- 
 brane. It lies between the tendons of the flexor 
 sublimis and those of the flexor profundus, and is rather nearer to 
 the radial than the ulnar side of the wrist. As soon as it appears 
 in the palm, the nerve lies superficial to all the tendons, and then 
 divides into two branches ; the external gives off branches to the 
 muscles of the ball of the thumb, namely, to the abductor pollicis, 
 the opponens pollicis, and the outer head of the flexor brevis 
 
DISSECTION OF THE PALM OF THE HAND. 261 
 
 pollicis, and then terminates in three digital nerves, two of which 
 are distributed to the thumb, and the third to the outer side of 
 the index finger ; the internal gives off two digital branches which 
 supply the rest of the forefinger, the middle finger, and the radial 
 side of the ring finger. 
 
 The two nerves to the thumb proceed, one on each side of the 
 long flexor tendon, to the last phalanx. 
 
 The third digital nerve runs along the radial side of the index 
 finger. The fourth descends towards the cleft between the index 
 and middle fingers, and subdivides into two branches, which supply 
 their opposite sides. The fifth is joined by a filament from one of 
 the ulnar digital nerves, and then subdivides above the cleft be- 
 tween the middle and ring fingers, to supply their opposite sides. 
 
 Two small branches are given off from the third and fourth 
 digital nerves, to supply the two outer lumbricales ; the two inner 
 being supplied by the ulnar. 
 
 About an inch and a quarter above the clefts between the 
 fingers, each digital nerve subdivides into two branches, between 
 which the digital. artery passes and bifurcates lower down; there- 
 fore a vertical incision down the cleft would divide the artery 
 before the nerve. 
 
 In their course along the fingers and thumb, the nerves lie 
 superficial to the arteries, and nearer to the flexor tendons. About 
 the middle of the first phalanx each nerve sends a branch, which 
 runs along the back of the finger nearly to the extremity, commu- 
 nicating with the dorsal branches, derived from the radial and 
 ulnar nerves.* Near the ungual phalanx another branch is dis- 
 
 * We find upon the cutaneous nerves of the hand and feet, little bodies termed, after 
 their discoverer, corpuscles of < Pacini.' Some of them will be found, by carefully 
 examining the trunk of a nerve, or one of its smaller branches, in the subcutaneous 
 tissue at the root of a finger. Each corpuscle is about ~th of an inch long, and is 
 attached by a slender fibro-cellular pedicle to the nerve upon which it is situated ; 
 through the pedicle, a single primitive nerve fibril passes into the corpuscle. The 
 corpuscle itself is composed of a series of concentric capsules, varying from twenty to 
 fifty in number, and separated by intervals containing fluid: and the nerve fibril 
 terminates by a dilated extremity in a central cavity, which exists in the axis of the 
 corpuscle. Their function is unknown. 
 
262 DISSECTION OF THE PALM OF THE HAND. 
 
 tributed to the skin around and beneath the root of the nail. Each 
 nerve terminates near the end of the finger in a brush of filaments, 
 with their points directed to the papillae of the skin. 
 Flexor ten- Immediately below the annular ligament the tendons 
 dons and separate from each other ; near the metacarpal joints 
 J s ' they pass in pairs, through strong fibrous rings (p. 256) 
 formed by the divisions of the palmar fascia. Below the meta- 
 carpal joint the two tendons for each finger enter the sheath 
 (theca), which confines them in their course along the phalanges. 
 It is formed by a strong fibrous membrane, which is attached to 
 the ridges on the phalanges, and converts the groove in front of 
 these bones into a complete canal, exactly large enough to contain 
 the tendons. The density of the sheath varies in particular 
 situations, otherwise there would be an obstacle to the easy 
 flexion of the fingers. To ascertain this, cut open one of the 
 sheaths along its entire length ; you will then see that it is much 
 stronger between the joints than over the joints themselves. 
 Through these sheaths, inflammation commencing in the integu- 
 ments of the finger may readily extend to the synovial membrane 
 of the tendon. 
 
 In cases of whitlow, when matter forms in the theca, the incision 
 should be made deep enough to lay open this fibro-osseous canal, 
 without which the incision will be of no use. It is obvious that 
 the incision should be made down the centre of the finger, to avoid 
 the digital nerves and arteries. If this opening be not timely 
 made, the flexor tendons are likely to slough, and the finger 
 becomes stiff.* 
 
 But what protects the joints of the fingers where the flexor 
 
 * On closer inspection it will be observed that the sheath is composed of bands of 
 fibres, which take different directions, and have received distinct names. The 
 strongest are called the 'ligamenta vaginalia.' They constitute the sheath over the 
 body of the phalanx, and extend transversely from one side of the bone to the other. 
 The 'ligamenta cruciata' are two slips, which cross obliquely over the tendons. The 
 'ligamenta annul aria' are situated immediately in front of the joints, and maybe 
 considered as thin continuations of the ligamenta vaginalia. They consist of delicate 
 fibres, which are attached on either side of the joints to the glenoid ligaments, and 
 pass transversely over the tendons. 
 
DISSECTION OF THE PALM OF THE HAND. 263 
 
 tendons play over them ? Look into an open sheath, and you 
 will see that in front of the joints the tendons glide over a smooth 
 fibre-cartilaginous structure, called the 6 glenoid ' ligament. 
 
 To facilitate the play of the tendons, the interior of the sheath, 
 as well as the tendons, is lined by a synovial membrane, of the 
 extent of which it is important to have a correct knowledge. With 
 a probe you may easily ascertain that the synovial membrane is 
 reflected from the sheath upon the tendons, a little above the 
 metacarpal joints of the fingers ; that is, nearly in a line with the 
 transverse fold in the skin in the lower third of the palm. Towards 
 the distal end of the finger, the synovial sheath stops short of the last 
 joint, so that it is not injured in amputation of the ungual phalanx. 
 
 And now notice how beautifully the tendons are adapted to each 
 other in their course along the finger. The superficial flexor, near 
 the root of the finger, becomes slightly grooved to receive the deep 
 flexor ; about the middle of the first phalanx it splits into two 
 portions, through which the deep flexor passes. The two portions 
 reunite below the deep tendon so as completely to embrace it, and 
 then divide a second time into two slips, which interlace with 
 each other and are inserted into the sides of the second phalanx. 
 The deep flexor, having passed through the opening of the super- 
 ficial one, is inserted into the base of the last phalanx.* 
 
 In what way are the tendons supplied with blood ? Eaise and 
 separate the tendons, and you will see that slender folds of synovial 
 membrane (vincula tendinum) run up from the phalanges to the 
 tendons ; when minutely injected, these folds are full of blood- 
 vessels. 
 
 The tendon of the flexor longus pollicis lies on the radial side of 
 the other tendons beneath the annular ligament. It passes between 
 the two portions of the flexor brevis pollicis and the two sesamoid 
 bones of the thumb, enters its proper sheath, and is inserted into 
 
 * In the museum of the College of Surgeons, a preparation is put up which shows 
 a beautiful piece of animal mechanics about the flexor tendons ; namely, that in its 
 passage along the phalanges the deep flexor forms at the first phalanx a kind of little 
 patella for the superficial one; but at the second phalanx the superficial flexor lies 
 deeper than the other, and forms a little patella for it. This is a very pretty mechani- 
 cal ingenuity to increase the leverage in each case. 
 
264 DISSECTION OF THE PALM OF THE HAND. 
 
 the base of the last phalanx. Its synovial sheath is prolonged 
 from the large bursa of the flexor tendons beneath the annular 
 ligament, and accompanies it down to the last joint of the 
 thumb ; consequently the sheath is injured in amputation of the 
 last phalanx. 
 
 A large and loose synovial sac, called the bursa of the 
 thTcarpus car P us > facilitates the play of the tendons beneath the 
 
 anterior annular ligament. It lines the under surface of 
 the ligament and the groove of the carpus, and is reflected in loose 
 folds over the tendons. It is prolonged up the tendons for an inch 
 and a half, or two inches, and forms a ' cul-de-sac ' above the 
 ligament. Below the ligament the bursa extends into the palm, 
 and sends off prolongations for each of the flexor tendons, which 
 accompany them down to the middle of the hand. You will easily 
 understand that, when the bursa is inflamed and distended by fluid, 
 there will be a bulging above the annular ligament, and another in 
 the palm, with perceptible fluctuation between them ; the unyield- 
 ing ligament causing a constriction in the centre.* 
 
 These four slender muscles, one for each finger, are 
 
 attached to the deep flexor tendons in the palm. All 
 of them arise from the radial side of the deep tendon of their 
 corresponding finger : the third and fourth often arise from the 
 adjacent sides of two tendons. Each terminates in a broad thin 
 tendon which passes over the radial side of the first joint of the 
 finger, and is inserted into the extensor tendon on the back of the 
 finger. Their action is to bend the first joint of the fingers. Being- 
 inserted near the centre of motion, they can move the fingers with 
 great rapidity. As they produce the quick motions of the musician's 
 fingers, they are called by anatomists ( fidicinales.' 
 
 The two inner lumbricales are supplied by the deep branch of 
 
 * I have met with only one instance in which this bursa communicated with the 
 wrist joint. It communicates always with the synovial sheath of the long flexor of 
 the thumb, in most cases with that of the flexors of the little finger, and but rarely 
 with that of the index, middle, and ring fingers. On this account inflammation of the 
 theca of the thumb or little finger is more liable to bo attended with serious conse- 
 quences than either of the others. 
 
DISSECTION OF THE PALM OF THE HAND. 265 
 
 the ulnar nerve ; the two outer by the third and fourth digital 
 branches of the median. 
 
 Let us now proceed to the muscles composing the ball of the 
 thumb and the little finger. The dissection of them requires con- 
 siderable care. 
 
 Muscles of the ^ e & rea ^ strength of the muscles of the ball of the 
 ball of the thumb (unde nomen pollicis), is one of the dis- 
 tinguishing features of the human hand. This strength 
 is necessary in order to oppose that of all the fingers. In addition 
 to its strength, the thumb enjoys perfect mobility. It has no less 
 than eight muscles to work it : namely, an abductor, an opponens, 
 two flexors, three extensors, and an adductor. Take first the 
 muscles of the ball. 
 
 This is the most superficial. It is a thin, flat muscle, 
 ar ^ ses from tne os scaphoides and the annular 
 ligament ; and is inserted by a flat tendon into the 
 base of the first phalanx of the thumb. Its action is to draw the 
 thumb away from the fingers. Reflect it from its insertion to 
 expose the following 
 
 This muscle arises from the os trapezium and the 
 
 Flexor ossis IT . 
 
 metacarpi annular ligament, and is inserted into the whole length 
 pollicis or of tbe metacarpal bone of the thumb. The action of 
 
 opponens. x 
 
 this powerful muscle is to oppose the thumb to all the 
 fingers. Eeflect it from its insertion, to expose the following 
 
 This muscle has two origins ; one from the annular 
 ligament and os ^S^ m the other from the os 
 trapezoides, os magnum, and the base of the third 
 metacarpal bone. It is inserted by two strong tendons into the 
 base of the first phalanx of the thumb ; the' superficial tendon 
 being connected witli the abductor pollicis, and the deep one with 
 the adductor pollicis. A sesamoid bone is found in each of the 
 tendons. The tendons of insertion of this muscle are separated by 
 the long flexor tendon of the thumb and the arteria magna pollicis. 
 Its action is to bend the first phalanx of the thumb. 
 Adductor This muscle arises from the palmar aspect of the 
 
 pollicis. shaft of the metacarpal bone of the middle finger ; its 
 
26G DISSECTION OF THE PALM OF THE HAND. 
 
 fibres converge and are inserted, along with the inner portion of 
 the flexor brevis pollicis, into the base of the first phalanx of the 
 thumb. Its action is to draw the thumb towards the palm, as when 
 we bring the tips of the thumb and little finger into contact. It is 
 supplied by the deep branch of the ulnar nerve, which also supplies 
 the inner head of the flexor brevis pollicis. The other muscles of 
 the ball of the thumb are supplied by the median nerve. 
 Muscles of the ^ e musc l es * the little finger correspond in some 
 ball of the measure with those of the thumb. Thus we have 
 ) finger. an a k(j uc t or? a flexor brevis, and an opponens minimi 
 digiti. 
 
 This, the most superficial of the muscles of the little 
 m^nimidigiti. nn g er ? arises from the pisiform bone, and from the 
 
 tendinous expansion of the flexor carpi ulnaris : it is 
 inserted by a flat tendon into the base of the first phalanx of the 
 little finger. Its action is to draw this finger from the rest. 
 
 This slender muscle may fairly be considered as a 
 minimi digiti. P ortion of tne preceding. It arises from the unciform 
 
 bone and annular ligament, and is inserted with the 
 tendon of the abductor into the base of the first phalanx of the 
 little finger. Its action is similar to that of the abductor. Between 
 the origins of the abductor and flexor brevis minimi digiti, the 
 deep branch of the ulnar artery and nerve sinks down to form the 
 deep palmar arch. 
 
 The last two muscles must be reflected from their 
 
 Opponens 
 
 digiti insertion, to expose ttre opponens d^g^t^ minimi. It 
 
 arises from the unciform bone and the annular ligament, 
 and is inserted along the shaft of the metacarpal bone of the little 
 finger. Its action is to draw this bone, the most movable of all 
 the metacarpal bones of the fingers, towards the thumb. Thus it 
 greatly strengthens the grasp of the palm. 
 
 Now cut through all the flexor tendons, and remove the deep 
 fascia of the palm, to see the deep arch of arteries and its branches. 
 Branches of T ne radial artery enters the palm at the angle 
 the radial ar- between the first and second metacarpal bones (be- 
 palm. 'tween the inner head of the flexor brevis and the 
 
DISSECTION OF THE PALM OF THE HAND. 2f>7 
 
 adductor pollicis), and gives off three branches the arteria 
 magna pollicis, the radialis indicis, and the palmaris profunda, 
 which unites with the ulnar to form the deep arch. 
 
 The arteria magna pollicis runs in front of the abductor indicis 
 (first dorsal interosseous), close along the metacarpal bone of the 
 thumb : in the interval between the lower portions of the flexor 
 brevis pollicis, the artery divides into two branches, which proceed 
 one on either side of the thumb, and inosculate at the apex of the 
 last phalanx. Their distribution and mode of termination are 
 similar to those of the other digital arteries. 
 
 The arteria radialis indicis runs between the abductor indicis 
 and adductor pollicis, along the radial side of the index finger to 
 the extremity, where it forms an arch with the other digital artery, 
 a branch of the ulnar. Near the lower margin of the adductor 
 pollicis, the radialis indicis generally receives a branch from the 
 superficial palmar arch. 
 
 The palmaris profunda is considered as the continuation of 
 the radial artery. It enters the palm between the inner head of 
 the flexor brevis and the adductor pollicis, resting upon the bases of 
 the metacarpal bones and the interosseous muscles, and inosculates 
 with the deep branch of the ulnar artery, thus completing the deep 
 palmar arch. From the curve of the arch small recurrent branches 
 ascend to supply the bones and joints of the carpus, inosculating 
 with the other carpal arteries. From the convexity of the arch 
 four small branches, called palmar interosseous (fig. 51, p. 258), 
 descend to supply the interosseous muscles, and near the clefts of 
 the fingers communicate with the digital arteries. These palmar 
 interosseous branches are sometimes of considerable size, and take 
 the place of one or more of the digital arteries, ordinarily derived 
 from the superficial palmar arch. Other branches, called 'per- 
 forating? pass between the upper ends of the metacarpal bones to 
 the back of the hand, and communicate with the carpal branches 
 of the radial and ulnar. 
 
 Depp branch ^ n ^ s nerve siks into the palm with the ulnaris pro- 
 of the ulnar funda artery, between the abductor and flexor brevis 
 nerve. minimi digiti. It then runs with the deep palmar 
 
268 MUSCLES OF THE BACK CONNECTED WITH THE ARM. 
 
 arch towards the radial side of the palm, and terminates in the 
 adductor pollicis, and inner head of the flexor brevis pollicis. 
 Between the pisiform and unciform bones, the nerve gives a 
 branch to each of the muscles of the little finger. Subsequently 
 it sends branches to each interosseous muscle and to the two 
 inner lumbricales. 
 
 The tendon of the flexor carpi radialis in the palm must now 
 be followed to its insertion into the bases of the second and third 
 metacarpal bones. 
 
 The dissection of the remaining muscles of the palm, called, 
 from their position, ' interosseij must be for the present post- 
 poned. 
 
 MUSCLES OF THE BACK CONNECTED WITH THE ARM. 
 
 Make an incision down the spine from the occiput to the 
 sacrum ; another from the last dorsal vertebra upwards and out- 
 ward to the acromion ; and a third from the sacrum along the 
 crest of the ilium ; then reflect the skin outwards from the dense 
 subcutaneous tissue, in which will be found the following cuta- 
 neous nerves. 
 
 Cutaneous These are derived from the posterior branches of the 
 
 nerves of spinal nerves, and correspond generally to the number 
 of the vertebrae. The posterior primary branches, much 
 smaller than the anterior, divide between the transverse processes 
 into external and internal branches. From the internal, which 
 become superficial near the spines of the vertebra?, are derived 
 those branches which supply the skin in the cervical and upper 
 dorsal regions ; from the' external, which appear near the angles of 
 the ribs, those which supply the skin of the lower dorsal and lumbar 
 regions. In the cervical and upper dorsal region, the cutaneous 
 nerves perforate the complexus, splenius, and trapezius ; in the 
 lower dorsal and lumbar region they perforate the serratus posticus 
 inferior and latissimus dorsi. As might be expected, the external 
 branches are the larger, especially in the loins, where some of them 
 
MUSCLES OF THE BACK CONNECTED WITH THE AKM. 269 
 
 descend over the crest of the ilium, and terminate in the skin of 
 the buttock. 
 
 Of these cutaneous nerves notice particularly the following : 
 
 The posterior branch of the second cervical nerve is called the 
 great occipital. It perforates the complexus, and ramifies upon 
 the scalp, with the branches of the occipital artery. 
 
 The cutaneous branch of the third cervical nerve also sends a 
 branch to the back of the scalp. 
 
 The cutaneous branch of the second dorsal nerve is the largest 
 of all the dorsal cutaneous nerves. It may be traced outwards 
 towards the spine of the scapula. 
 
 The posterior branch of the second lumbar nerve perforates the 
 fascia lumborum near the posterior superior spine of the ilium, 
 and runs over the crest of the ilium, to supply the skin of the 
 buttock. 
 
 The trapezius and latissimus dorsi, which form the first layer of 
 muscles, must now be cleaned by dissecting in the course of their 
 fibres. 
 
 _ Alone, this muscle is triangular ; with its fellow, it 
 
 presents a trapezoid form. It arises from the inner 
 fourth, more or less, of the superior curved line of the occiput ; 
 from the ligamentum nuchse,* from the spines of the seventh 
 cervical, and all the dorsal vertebrae, and from their supraspinous 
 ligaments. The fibres converge towards the shoulder. The upper 
 are inserted fleshy into the external third of the clavicle ; the 
 middle, into the inner border of the acrornion and spine of the 
 scapula ; the lower terminate in a thin tendon, which plays over 
 the triangular surface at the back of the scapula, and is inserted 
 into the beginning of the spine. The insertion of the trapezius 
 exactly corresponds to the origin of the deltoid, and the two 
 
 * The ' ligamentum nuchse ' is, in man, only a rudiment of the great elastic ligament 
 which supports the weight of the head in quadrupeds. It extends from the spine of 
 the occiput to the spines of all the cervical vertebrse except the atlas ; otherwise it 
 would impede the free rotation of the head. In the giraffe this ligament is six feet 
 long, and as thick as a man's forearm. I am told by Professor Quekctt, that when 
 divided it shrinks at least two feet. 
 
270 MUSCLES OF THE BACK CONNECTED WITH THE ARM. 
 
 muscles are connected by a thin aponeurosis over the spine and 
 acromion. If both the trapezius muscles be exposed, you will see 
 that, between the sixth cervical and the third dorsal vertebra, 
 their origin presents an aponeurotic space of an elliptical form. 
 
 The fixed point of the muscle being at the spine, all its fibres 
 tend to raise the shoulder. The deltoid cannot raise the humerus 
 beyond an angle of sixty degrees : beyond this the elevation of the 
 arm is principally effected by the action of the trapezius rotating 
 the scapula. It is in strong action when a weight is borne upon 
 the shoulders ; again, its middle and inferior fibres act powerfully 
 in drawing the scapula backwards, as in preparing to strike a blow. 
 If both muscles act, they draw the head backwards; if one, it 
 draws the head to the same side. It is supplied by the nervus 
 accessorius and the cervical plexus, and by the superficialis colli 
 artery. 
 
 This broad flat muscle occupies the lumbar and 
 lower dorsal region, and thence extends to the arm, 
 'ScoC where it forms part of the posterior boundary of the 
 
 axilla. It arises from the posterior third of the external lip of 
 the crest of the ilium, from the spinous processes of the two upper 
 sacral, all the lumbar and the six lower dorsal vertebrae by a strong 
 aponeurosis; and, lastly, from the three or four lower ribs by 
 digitations, which correspond with those of the external oblique 
 muscle of the abdomen. All the fibres converge towards the 
 axilla, where they form a thick muscle, which curves round the 
 inferior angle of the scapula, and is inserted by a broad, flat 
 tendon, into the bottom of the bicipital groove of the humerus. 
 The tendon is about two inches broad, and lies in front of that of 
 the teres major, from which it is separated by a large bursa* 
 
 The latissimus dorsi draws the humerus inwards and backwards ; 
 rotating it also inwards. It also co-operates with the pectoralis 
 major in pulling any object towards the body: if the humerus be 
 the fixed point, it raises the body, as in climbing. The object of 
 
 * The latissimus dorsi sometimes receives a distinct accessory slip from the inferior 
 angle of the scapula. It is supplied by the long subscapular nerve. 
 
MUSCLES OF THE BACK CONNECTED WITH THE ARM. 271 
 
 the muscle arising so high up the back is, that the transverse 
 fibres of the muscle may strap down the inferior angle of the 
 scapula. It sometimes happens that the scapula slips above the 
 muscle : this displacement is readily recognised by the unnatural 
 projection of the lower angle of the bone, and the impaired move- 
 ments of the arm.* 
 
 Between the base of the scapula, the trapezius, and the upper 
 border of the latissimus dorsi, a triangular space is observed when 
 the arm is raised, in which the lower fibres of the rhomboideus 
 major and part of the sixth intercostal space, are exposed. Imme- 
 diately above the crest of the ilium, between the free margins of 
 the latissimus dorsi and external oblique, there is, also, an interval 
 in which a little of the internal oblique can be seen. 
 
 This dense shining aponeurosis of the back is situated 
 between the serrati postici and the erector spinae, of 
 which muscle it forms the posterior part of the sheath. 
 It is pointed above, where it is continuous with the deep cervical 
 fascia, broader and stronger below. It consists of tendinous fibres, 
 which are attached internally to the spines of the six or seven 
 lower dorsal, all the lumbar and sacral vertebrae ; externally, to the 
 angles of the ribs ; and inferiorly it is blended with the tendons 
 of the serratus posticus inferior and latissimus dorsi. When sup- 
 puration takes place in the loins, constituting ' lumbar abscess ' in 
 connection with spinal disease, the matter is seated beneath this 
 aponeurosis, and is therefore a long time in coming to the surface. 
 Eeflect the trapezius from its insertion. On its under surface 
 see the ramifications of its nutrient artery, the superficialis coll'i 
 (a branch of the posterior scapular). A large nerve, the spinal 
 accessory, enters its under surface near the clavicle, and divides 
 into filaments, some of which ascend, others descend in its 
 substance. 
 
 * We hare seen an instance of this displacement. There was great projection of 
 the inferior angle of the scapula, especially when the man attempted to raise the arm. 
 He could not raise the arm beyond a right angle, unless firm pressure was made on 
 the lower angle of the scapula, so as to supply the place of the rausciilar strap. 
 Whether the scapula can be replaced or not, apply a firm bandage round the chest. 
 
272 MUSCLES OF THE BACK CONNECTED WITH THE ARM. 
 
 Spinal acces- This nerve is one of the three divisions of the eighth 
 sory nerve, pair of cerebral nerves. It arises from the lateral part 
 of the cervical portion of the spinal cord by several roots, some of 
 which are as low as the sixth cervical vertebra. Formed by the 
 union of these roots, the nerve enters the skull through the 
 foramen magnum, and leaves it again through the foramen 
 jugulare. It then runs behind the internal jugular vein, traverses 
 obliquely the upper third of the sterno-mastoid, and crosses the 
 posterior triangle of the neck to the trapezius, which it supplies 
 (p. 15). 
 
 Beneath the trapezius we have to examine the second layer, 
 consisting of three muscles connected with the scapula ; namely, 
 the levator anguli scapulae, the rhomb oideus major and minor. 
 The scapula must be adjusted so as to stretch their fibres. 
 Levator an- This muscle is situated at the side of the neck. It 
 gull scapulae, arises by four tendons from the posterior tubercles of 
 the transverse processes of the four upper cervical vertebrae. The 
 muscular slips to which the tendons give rise, form a single 
 muscle, which descends down the side of the neck, and is inserted 
 into the posterior border of the scapula between its spine and 
 superior angle. Its action is to raise the posterior angle of the 
 scapula ; as, for instance, in shrugging the shoulders. Its nerve 
 comes from the fifth and sixth cervical. 
 
 P, These flat muscles extend from the spinous processes 
 
 ideus major of the vertebrae to the base of the scapula. They often 
 and minor, appear like a single muscle. The rhomboideus minor, 
 the higher of the two, arises by a thin aponeurosis from the spinous 
 processes of the last cervical and the first dorsal vertebra, and is 
 inserted into the base of the scapula opposite its spine. The 
 rhomboideus major arises by tendinous fibres from the spinous 
 processes of the four or five upper dorsal vertebrae, and is inserted 
 by fleshy fibres into the base of the scapula between its spine and 
 inferior angle. The action of these muscles is to draw the scapula 
 upwards and backwards. They are the antagonists of the serratus 
 magnus. 
 
 The nerve of the rhomboid muscles (posterior scapular) is a 
 
MUSCLES OF THE BACK CONNECTED WITH THE ARM. 273 
 
 branch of the fifth and sixth cervical. It passes outwards beneath 
 the lower part of the levator anguli scapulae, to which it sends a 
 branch, and is lost in the under surface of the rhomboidei. 
 Omo . This muscle extends from the scapula to the os 
 
 hyoideus. hyoides, and consists of two long narrow muscular por- 
 tions, connected by an intermediate tendon beneath the sterno- 
 mastoid. The posterior portion only can be seen in the present 
 dissection. It arises from the scapula, close behind the notch, 
 and from the ligament above the notch. From thence the slender 
 muscle passes forwards across the lower part of the neck, beneath 
 the sterno-mastoid, where it changes its direction and ascends 
 nearly vertically, to be attached to the os hyoides at the junction 
 of the body with the greater cornu (p. 22). Thus the two por- 
 tions of the muscle form beneath the sterno-mastoid an obtuse 
 angle, of which the apex is tendinous, and of which the angular 
 direction is maintained by a layer of fascia, proceeding from 
 the tendon to the first rib and the clavicle. Its action is to 
 depress the os hyoides. Its nerve comes from the descendens 
 noni. 
 
 Supra-scapu- This artery (transversalis humeri), a branch of the 
 lar artery. thyroid axis, runs beneath and parallel with the clavicle, 
 over the lower end of the scalenus anticus to the upper border of 
 the scapula, where it usually passes above the ligament, bridging 
 over the notch. It ramifies in the supra spinous fossa, supplying 
 the supra-spinatus, and then passes under the acromion to the 
 infra -spinous fossa, where it inosculates freely with the dorsalis 
 scapula, a branch of the subscapular. It sends off the supra- 
 acromial branch, which ramifies upon the acromion, anastomosing 
 with the other acromial arteries derived from branches of the 
 axillary. The supra-scapular vein terminates either in the sub- 
 clavian or in the external jugular. 
 
 The supra-scapular nerve, a branch of the fifth and sixth 
 cervical, runs with the corresponding artery, and after passing 
 through the supra-scapular notch, is distributed to the supra- 
 spinatus and infra-spinatus. In the supra-spinous fossa, this 
 nerve sends a small branch to the shoulder-joint. 
 
 T 
 
274 MUSCLES OF THE BACK CONNECTED WITH THE ARM. 
 
 Posterior This ar ^ er y? sometimes called the 6 transversalis 
 
 scapular colli,' is usually described as arising from the thyroid 
 axis, but it comes very frequently from the subclavian 
 in the third part of its course. It runs across the lower part of 
 the neck, above, or between the nerves of the brachial plexus, 
 towards the posterior superior angle of the scapula. Here it pur- 
 sues its course along the posterior border of the scapula beneath 
 the levator anguli scapulae and the rhomboidei, anastomosing with 
 branches of the supra-scapular and sub-scapular arteries. The 
 corresponding vein joins the external jugular or the subclavian. 
 
 Divide the rhomboid muscles near their insertion, and trace 
 the artery to the inferior angle of the scapula, where it terminates 
 in the rhomboidei, serratus magnus, and latissimus dorsi. 
 
 Numerous muscular branches arise from the posterior scapular. 
 One, the superficicdis colli, is given off near the upper angle of 
 the scapula for the supply of the trapezius. 
 
 Divide and reflect the latissimus dorsi below the inferior angle 
 of the scapula, and draw the scapula forcibly outwards, to have a 
 more perfect view of the extent of the serratus magnus than was 
 seen in the axilla. The abundance of cellular tissue in this situa- 
 tion is necessary for the play of the scapula on the chest. 
 
 This broad flat muscle intervenes between the scapula 
 
 mamma an( * tne T ^ s ' Jt ar ^ ses ^J nine nesn j digitations from 
 the eight upper ribs, each rib giving origin to one, 
 and the second to two. The four lower digitations correspond 
 with those of the external oblique muscle of the abdomen. All 
 the fibres pass backwards, and converge to be inserted along the 
 posterior border of the scapula, chiefly near the upper and lower 
 angles. 
 
 This is the most important of the muscles which regulate the 
 movements of the scapula; it draws the scapula forwards and 
 thus gives additional reach to the arm ; it counteracts all forces 
 which tend to push the scapula backwards ; for instance, when a 
 man falls forwards upon his hands, the serratus magnus sustains 
 the shock, and prevents the scapula from being driven back to the 
 spine. Supposing the fixed point to be at the scapula, some 
 
MUSCLES OF THE SHOULDER. 275 
 
 anatomists ascribe to it the power of raising the ribs ; hence Sir 
 Charles Bell called it the external respiratory muscle, as opposed 
 to the internal respiratory muscle, the diaphragm. 
 
 The nerve which supplies it is a branch of the fifth and sixth 
 cervical nerve : it descends along its outer surface (p. 226). 
 
 Divide the serratus magnus near the scapula, and remove the 
 arm by sawing through the middle of the clavicle, cutting through 
 the axillary vessels and nerves. These should be tied to the 
 coracoid process. After the removal of the arm, examine the 
 precise insertion of the preceding muscles. 
 
 DISSECTION OF THE MUSCLES OF THE SHOULDER. 
 
 Dissect first the cutaneous nerves of the shoulder; 
 Cutaneous these are derived, partly from the branches of the 
 
 nerves of the . ' r J . 
 
 shoulder. cervical plexus which descend over the acromion (p. 1 7 ), 
 partly from the circumflex nerve, of which one or two 
 branches turn round the posterior border of the deltoid ; others 
 perforate the muscle, each accompanied by a small artery. 
 
 Notice the strong layer of fascia upon the surface of the del- 
 toid, which extends from the aponeurosis covering the muscles 
 on the back of the scapula, and is continuous with the fascia of 
 the arm. It dips down between the fibres of the muscle, dividing 
 it into large bundles. This fascia must be removed. 
 
 The great muscle which covers the shoulder-joint is 
 named deltoid, from its resemblance to the Greek A 
 reversed. It arises from the external third of the clavicle, from 
 the acromion, and from the spine of the scapula down to the 
 triangular surface at its root. This origin, which corresponds to 
 the insertion of the trapezius, is tendinous and fleshy everywhere, 
 except at the commencement of the spine of the scapula, where it 
 is simply tendinous, and connected with the infra-spinous aponeu- 
 rosis. The muscular fibres descend, the anterior backwards, the 
 posterior forwards, the middle perpendicularly ; all converge to a 
 tendon which is inserted into a rough surface on the outer side of 
 
 T2 
 
276 
 
 MUSCLES OF THE SHOULDER. 
 
 Fig. 52, 
 
 the humerus, a little above the middle of the shaft. The insertion 
 of the tendon extends one inch and a half along the humerus, and 
 terminates in a smaller V-shaped form, the origin of the brachialis 
 anticus being on either side. 
 
 The muscular bundles composing the deltoid have a peculiar 
 arrangement: a peculiarity arising from its broad origin and its 
 narrow insertion. It consists in the interposition of tendons 
 between the bundles for the attachment of the muscular fibres. 
 The annexed woodcut shows this beautiful arrangement better 
 than any description. The action of the muscle is not only con- 
 centrated upon one point, but its power is also greatly increased, 
 by this arrangement. 
 
 It raises the arm ; but it cannot do so beyond an 
 
 the deltoid. an gl e f sixty degrees. The elevation of the arm 
 
 beyond this angle is effected through the elevation of 
 
 the shoulder by the trapezius and serratus magnus. Its anterior 
 
 fibres draw the arm forwards ; its 
 posterior, backwards. 
 
 This powerful muscle is well sup- 
 plied with blood, by the anterior 
 and posterior circumflex, the tho- 
 racica humeraria, the thoracica 
 acromialis, all from the axillary 
 artery ; also by the deltoid branch 
 of the brachial. Its nerve is the 
 circumflex. 
 
 The deltoid gives the rotundity 
 to the shoulder. When the head 
 of the humerus is dislocated into 
 the axilla, the fibres of the muscle 
 run vertically to their insertion ; 
 hence the flattening of the deltoid, 
 and the greater prominence of the 
 acromion. 
 
 Below the deltoid we generally meet with ununited fracture of 
 the humerus ; owing to the muscle raising the upper fragment. 
 
 ANALYSIS OF THE DELTOID. 
 
MUSCLES OF THE SHOULDER. 277 
 
 Reflect the deltoid from its origin, and turn it downwards. 
 Observe the ramifications of the circumflex artery and nerve, on its 
 under surface : also the large bursa between it and the tendons 
 inserted into the head of the humerus. See how the muscle pro- 
 tects the shoulder-joint; how it covers the coraco-acromial liga- 
 ment, the head, neck, and upper part of the humerus, as well as 
 the tendons inserted into the greater tuberosity. 
 
 A bursa of large size is situated between the deltoid, 
 
 T> J 
 
 the deltoid!' an( ^ ^he tendons inserted into the head of the humerus. 
 
 It extends for some distance beneath the acromion and 
 the coraco-acromial ligament, and covers the great tuberosity of 
 the humerus. I have seen it communicating by a wide opening 
 with the shoulder-joint, but this is a rare exception. Its use is to 
 facilitate the movements of the head of the bone under the 
 acromial arch. 
 
 Posterior ^ n ^ s ar t er y i g given off from the axillary : it runs 
 
 circumflex behind the surgical neck of the humerus, through a 
 
 quadrilateral opening, bounded above by the sub- 
 scapularis and teres minor, below by the teres major, externally 
 by the neck of the humerus, and internally by the long head of 
 the triceps (p. 229). Its branches terminate on the under surface 
 of the deltoid, anastomosing with the anterior circumflex, acromial 
 thoracic, and supra-scapular arteries. 
 
 From the posterior circumflex, a branch descends in the sub- 
 stance of the long head of the triceps, to inosculate with the 
 superior profunda ; this is one of the channels through which the 
 circulation would be carried on, if the axillary were tied in the 
 last part of its course. 
 
 This nerve, a branch of the posterior cord of the 
 Circumflex ax iHary plexus, runs with the posterior circumflex 
 
 nerve. 
 
 artery. It sends a branch to the teres minor, one or 
 two to the integuments of the shoulder, and terminates in the 
 substance of the deltoid. The proximity of this nerve to the head 
 of the humerus explains the occasional paralysis of the deltoid, 
 after dislocation or fracture of the humerus. The nerve is apt to 
 be injured, if not actually lacerated by the pressure of the bone. 
 
278 MUSCLES OF THE SHOULDER. 
 
 In the summer of 1840, a man was admitted into the hospital 
 with a severe injury to the shoulder, and died of delirium tremens. 
 On examination the humerus was found broken high up, the 
 capsule of the joint opened, and the circumflex nerve torn com- 
 pletely across.* 
 
 The muscles of the dorsum of the scapula are covered by a 
 strong aponeurosis, firmly attached to the spine and borders of the 
 bone. At the posterior edge of the deltoid, it divides into two 
 layers, one of which passes over, the other under, the muscle. 
 Eemove the aponeurosis, so far as it can be done without injury 
 to the muscular fibres which arise from its under surface. 
 
 This muscle arises from the posterior two-thirds of 
 the i^fra-spinous fossa, and from the aponeurosis which 
 covers it. The fibres converge to a tendon, which is at 
 first contained in the substance of the muscle, and then proceeds 
 over the capsule of the shoulder-joint to be inserted into the 
 greater tuberosity of the humerus. Its nerve comes from the 
 supra-scapular. 
 
 This long narrow muscle is situated below the infra- 
 spinatus, along the inferior border of the scapula. It 
 arises from the dorsum of the scapula, close to the inferior border. 
 The fibres ascend parallel with those of the infra-spinatus, and 
 terminate in a tendon, which passes over the capsule of the 
 shoulder- joint, and is inserted into the lowest depression on the 
 great tuberosity of the humerus, and by muscular fibres into the 
 bone below it. It is supplied by a branch of the circumflex 
 nerve, which has usually a small ganglion upon it. 
 
 The action of the infra-spinatus and teres minor is to rotate the 
 humerus outwards. 
 
 This muscle is closely connected with the latissimus 
 
 .Leres major. . 
 
 dorsi, and extends from the inferior angle of the scapula 
 to the humerus, contributing to form the posterior boundary of the 
 axilla. It arises from the flat surface at the inferior angle of the 
 back of the scapula, and from its inferior border, and terminates 
 
 * See preparation in Museum of St. Bartholomew's Hospital, series 3, no. 42, 
 
MUSCLES OF THE SHOULDER. 279 
 
 upon a flat tendon, two inches in breadth, which is inserted into the 
 inner edge of the bicipital groove of the humerus, behind and a 
 little below the tendon of the latissimus dorsi. Its action is to 
 draw the humerus backwards. It is supplied by the middle sub- 
 scapular nerve. 
 
 You will find a bursa in front of, and another behind the tendon 
 of the teres major; the former separates it from the latissimus 
 dorsi, the latter from the bone. 
 
 This muscle arises from the posterior two-thirds of 
 Supra- ^g supra-spinous fossa, and from its aponeurotic cover- 
 
 spmatus. . IT. 
 
 ing. It passes under the acromion, over the shoulder- 
 joint, and is inserted by a strong tendon into the greater tuber- 
 osity of the humerus. To see its insertion, the acromion should 
 be sawn off near the neck of the scapula. Its action is to assist 
 the deltoid in raising the arm. Its nerve is derived from the 
 supra- scapular. 
 
 This muscle occupies the subscapular fossa. It arises 
 Subscapu- from the posterior three-fourths of the fossa, from three 
 or four tendinous septa attached to the oblique ridges 
 on its surface. The fibres converge towards the neck of the 
 scapula, where they terminate upon three or four tendons, which 
 are concealed amongst the muscular fibres, and are inserted into 
 the lesser tuberosity of the humerus. Its broad insertion is closely 
 connected with the capsule of the shoulder-joint, which it com- 
 pletely protects upon its inner side. Its action is to rotate the 
 humerus inwards. The nerve which supplies it comes from the 
 posterior cord which gives off the circumflex and musculo -spiral. 
 
 The coracoid process, with the coraco-brachialis and short head 
 of the biceps, form an arch, under which the tendon of the sub- 
 scapularis plays. There are several bursce about the tendon. 
 One of considerable size on the upper surface of the tendon, facili- 
 tates its motion beneath the coracoid process and the coraco- 
 brachialis : this sometimes communicates with the large bursa 
 under the deltoid. Another is situated between the tendon and 
 the capsule of the joint, and almost invariably communicates 
 with it. 
 
280 TRICEPS. 
 
 Now reflect the muscles from the surfaces of the scapula, to 
 trace the arteries which ramify upon it. 
 
 This artery, a branch of the thyroid axis, runs under 
 of supra- an( ^ parallel with the clavicle, and passes above the 
 scapular notch of the scapula, into the supra-spinal fossa: it 
 sends a branch to the supra -spinatus, another to the 
 shoulder-joint, and then descends over the neck of the scapula 
 into the fossa below the spine, where it inosculates directly with 
 the dorsalis scapulae. Its branches ramify upon the bone, and 
 supply the infra-spinatus and teres minor. 
 
 The supra-scapular nerve passes most frequently through the 
 notch of the scapula, accompanies the corresponding artery, and 
 supplies the supra and infra-spinatus. 
 
 Dorsalis This artery, after passing through the triangular 
 
 scapulae space (p. 229), curves round the inferior border of the 
 scapula, which it sometimes grooves, to the infra- 
 spinous fossa, where it ascends close to the bone, and anasto- 
 moses with the supra and posterior scapula arteries. 
 
 The frequent communications about the scapula "between the 
 branches of the subclavian and axillary arteries, would furnish a 
 free current of blood to the arm, if the subclavian were tied above 
 the clavicle (p. 60). 
 
 This muscle, which arises by three heads, and was 
 
 Triceps . . . . 
 
 extensor only partially seen in the dissection of the upper arm 
 cubiti. ^ 229 ), should now be fully examined. The long head 
 
 arises immediately below the glenoid cavity of the scapula, by a 
 strong tendon which is connected with the capsule of the shoulder- 
 joint. The second or external head arises from the posterior part 
 of the humerus, below the insertion of the teres minor ; the third 
 or internal head arises from the posterior part of the humerus, 
 below the teres major. The precise origin of these heads from the 
 humerus may be ascertained by following the superior profunda 
 artery and musculo -spiral nerve, which intervene between them. 
 The three portions of the muscle terminate upon a broad tendon, 
 which covers the back of the elbow-joint, and is inserted into the 
 summit and sides of the olecranon; it is also connected with the 
 
TRICEPS. 281 
 
 fascia on the back of the forearm. The reason of this connection 
 is, that the same muscle which extends the forearm may at the 
 same time tighten the fascia which gives origin to the extensors of 
 the wrist and fingers. This is just what we observed in the case of 
 the biceps, and its semi -lunar expansion in the fascia of the forearm. 
 
 Between the tendon and olecranon is a bursa, commonly of 
 small size, but sometimes so large as to extend upwards behind 
 the capsule of the joint. This bursa must not be mistaken for 
 that which is always found between the skin and the olecranon, 
 and is so often injured by a fall on the elbow. 
 
 By dividing the triceps transversely a little above the elbow, 
 and turning down the lower portion, it will be observed that some 
 of the muscular fibres terminate upon the capsule of the joint. 
 They have been described by some anatomists as a distinct muscle, 
 under the name of ( subanconeus ; ' their use is to draw up the 
 capsule, so that it may not be injured during extension of the 
 arm. The subanconeus is in this respect analogous to the sub- 
 crurseus muscle of the thigh. Observe the bursa under the tendon, 
 and the arterial arch formed upon the back part of the capsule by 
 the superior profunda and the anastomotica magna (fig. 50, p. 240). 
 
 Trace the continuation of the superior profunda artery (p. 239), 
 and musculo-spiral nerve round the posterior part of the humerus. 
 They lie in a groove on the bone, between the external and in- 
 ternal heads of the triceps, and are protected by an aponeurotic 
 arch thrown over them by the external head of the triceps. After 
 supplying the muscles, the artery continues along the outer side 
 of the arm between the brachialis anticus and supinator radii 
 longus, and inosculates with the radial recurrent. It gives off a 
 branch which runs down between the triceps and the bone, and 
 inosculates at the back of the elbow with the anastomotica magna 
 and posterior interosseous recurrent. The musculo-spiral nerve 
 which accompanies the artery sends branches to supply the three 
 portions of the triceps, the supinator radii longus, and extensor 
 carpi radialis longior.* It then divides into the posterior inter- 
 
 * In some (rare) instances, the brachialis anticus receives a branch from the 
 mus culo-spiral. 
 
282 DISSECTION OF THE BACK OF THE FOREARM. 
 
 osseous and radial nerves. A small branch of this nerve, which 
 passes through the substance of the triceps to supply the anconeus, 
 must be made out. The cutaneous branches of the musculo- spiral 
 nerve have been already dissected (p. 233). 
 
 DISSECTION OF THE BACK OF THE FOEEARM. 
 
 Bemove the skin from the back of the forearm, hand, and fingers. 
 Observe the subcutaneous bursa over the olecranon. It is com- 
 monly of considerable size, and, if distended, would appear nearly 
 as large as a walnut. Another bursa is sometimes found a little 
 lower down upon the ulna. A subcutaneous bursa is generally 
 placed over the internal condyle, another over the external. A 
 bursa is also situated over the styloid process of the ulna ; this 
 sometimes communicates with the sheath of the extensor carpi 
 ulnaris. Small bursce are sometimes developed in the cellular 
 tissue over each of the knuckles. 
 
 The cutaneous veins from the back of the hand and forearm 
 join the venous plexus at the bend of the elbow (see p. 234). 
 
 They are the external cutaneous branches of the 
 Cutaneous musculo-spiral, branches of the internal cutaneous, 
 
 nerves of the r 
 
 back of the and of the external cutaneous. The greater number 
 d of these nerves ma y be traced down to the back of 
 
 the wrist. 
 
 The skin on the back of the hand is united to the subjacent 
 tendons by an abundance of loose connective tissue, in which 
 we find large veins, and branches of the radial and ulnar nerves. 
 The dorsal branch of the ulnar nerve passes beneath the ten- 
 don of the flexor carpi ulnaris, over the internal lateral liga- 
 ment of the wrist ; and divides upon the back of the hand into 
 filaments, which supply the back of the little finger, the ring 
 finger, and the ulnar side of the middle finger. The radial nerve 
 passes obliquely beneath the tendon of the supinator longus, and 
 subdivides into branches, which supply both sides of the back of 
 
DISSECTION OF THE BACK OF THE FOREAKM. 283 
 
 the thumb and forefinger, and the radial side of the middle 
 finger.* 
 
 The radial nerve commonly gives off a branch which joins that 
 division of the ulnar nerve which supplies the radial border of the 
 ring and contiguous side of the middle finger. 
 
 The fascia on the back of the forearm is composed of fibres 
 interlacing and stronger than that upon the front of the forearm. 
 It is attached to the condyles of the humerus and to the olecranon, 
 and is strengthened by an expansion from the tendon of the triceps. 
 Along the forearm it is attached to the ridge on the posterior part 
 of the ulna. Its upper third gives origin to the fibres of the 
 muscles beneath it, and separates them by septa, to which their 
 fibres are also attached. 
 
 Posterior ^^ s snou ld be considered as a part of the fascia of 
 
 annular the forearm, strengthened by oblique aponeurotic 
 fibres on the back of the wrist to confine the extensor 
 tendons, These fibres are attached to the styloid process of the 
 radius, and thence pass obliquely inwards to the inner side of the 
 wrist, where they are connected with the pisiform and cuneiform 
 bones. Observe that they pass below the styloid process of the 
 ulna, to which they are in no way attached, otherwise the rotation 
 of the radius would be impeded. 
 
 From the deep surface of this 6 so-called' ligament, processes 
 are attached to the ridges on the back of the radius, so as to form 
 six distinct sheaths for the passage of the extensor tendons. 
 Counting from the radius, the first sheath contains the tendons of 
 the extensor ossis metacarpi and the extensor primi internodii 
 pollicis; the second, the tendons of the extensor carpi radialis 
 longior and brevior ; the third, the tendon of the extensor secundi 
 
 * The relative share which the radial and ulnar nerves take in supplying the fingers 
 varies. Under any arrangement the thumb and each finger has two dorsal nerves, 
 one on either side, of which the terminal branches reach the root of the nail. They 
 supply filaments to the skin on the back of the finger, and have frequent communica- 
 tions with the palmar digital nerves. In some instances one or more of the dorsal 
 nerves do not extend beyond the first phalanx ; their place is then supplied by a branch 
 from the palmar nerve. 
 
284 DISSECTION OF THE BACK OF THE FOREARM. 
 
 internodii pollicis ; the fourth, the tendons of the indicator and 
 the extensor communis digitorum ; the fifth, the tendon of the 
 extensor minimi digiti ; and the sixth, the tendon of the extensor 
 carpi ulnaris. All the sheaths are lined by synovial membranes, 
 which extend nearly to the insertions of their tendons. In a few 
 instances, one or more of them communicate with the wrist- 
 joint. 
 
 The fascia of the metacarpus consists of a thin fibrous layer, 
 continued from the posterior annular ligament. It separates the 
 extensor tendons from the subcutaneous veins and nerves, and is 
 attached to the radial side of the second metacarpal bone, and the 
 ulnar side of the fifth. 
 
 The fascia must be removed from the muscles, with- 
 ou ^ i n j ur i n g the muscular fibres which arise from its 
 the back of under surface. Preserve the posterior annular liga- 
 ment. The following muscles are now exposed, and 
 should be examined in the order in which they are placed, pro- 
 ceeding from the radial to the ulnar side : 1. The supinator radii 
 longus (already described, p. 249). 2. The extensor carpi radi- 
 alis longior. 3. The extensor carpi radialis brevior. 4. The 
 extensor communis digitorum. 5. The extensor minimi digiti. 
 6. The extensor carpi ulnaris. 7. The anconeus. 
 
 A little below the middle of the forearm, the extensors of the 
 wrist and fingers diverge from each other, leaving an interval, in 
 which are seen the three extensors of the thumb the extensor 
 ossis metacarpi pollicis, the extensor primi internodii pollicis, and 
 the extensor secundi internodii pollicis. The two former cross the 
 radial extensors of the wrist, and pass over the lower third of the 
 radius. 
 
 Between the second and third extensors of the thumb, we ob- 
 serve a part of the lower end of the radius, which is not covered 
 either by muscle or tendon. This subcutaneous portion of the 
 bone is immediately above the prominent tubercle in the middle 
 of its lower extremity, and, since it can be easily felt through the 
 skin, it presents a convenient place for examination in doubtful 
 cases of fracture. 
 
DISSECTION OF THE BACK OF THE FOREARM. 285 
 
 Extensor ^is musc l e * s partly covered by the supinator radii 
 
 carpi radi- longus. It arises from the lower third of the ridge, 
 onglor ' leading to the external condyle of the humerus, and 
 from the intermuscular septum, descends along the outer side of 
 the forearm, and terminates about the middle, in a flat tendon, 
 which passes beneath the extensor ossis metacarpi, and primi 
 internodii pollicis, traverses a groove on the outer and back part 
 of the radius, lined by a synovial membrane, and is inserted 
 into the radial side of the carpal end of the metacarpal bone of 
 the index finger. Previous to its insertion, the tendon is crossed 
 by the extensor secundi internodii pollicis. It is supplied by a 
 branch from the musculo-spiral nerve. 
 
 Extensor This muscle arises from the external condyle and 
 
 carpi radialis from the external lateral ligament of the elbow-joint. 
 The muscular fibres terminate near the middle of the 
 forearm, upon the under surface of a flat tendon, which descends, 
 covered by that of the extensor carpi radialis longior, beneath the 
 first two extensors of the thumb. The tendon traverses a groove 
 on the back of the radius, on the same plane with that of the long 
 radial extensor, but lined by a separate synovial membrane, and is 
 inserted into the radial side of the metacarpal bone of the middle 
 finger. A bursa is generally found between the tendon and the 
 bone. Its nerve comes from the posterior interosseous nerve. 
 -P , This muscle arises from the common tendon attached 
 
 licensor 
 
 digitorum to the external condyle, from the septa between it and 
 communis. ^ con tiguous muscles, and from its strong fascial 
 covering. About the middle of the forearm the muscle divides 
 into three or four fleshy slips, terminating in as many flat tendons, 
 which pass beneath the posterior annular ligament, through a 
 groove on the back of the radius lined by synovial membrane. On 
 the back of the hand they become broader and flatter, and diverge 
 from each other towards the metacarpal joints of the fingers, 
 where they become thicker and narrower, and give off on each 
 side a fibrous expansion, which covers the sides of the joint. Over 
 the first phalanx of the finger, each tendon again spreads out, 
 receives the expanded tendons of the lumbricales and interossei 
 
286 DISSECTION OF THE BACK OF THE FOREARM. 
 
 muscles, and divides at the second phalanx into three portions, of 
 which the middle is inserted into the upper end of the second 
 phalanx; the two lateral, reuniting over the lower end of tte 
 second phalanx, are inserted into the upper end of the third.* 
 
 Observe the oblique aponeurotic slips which connect the tendons 
 on the back of the hand. They are subject to great variety. The 
 tendon of the index finger is commonly free ; it is situated on the 
 radial side of the proper indicator tendon, and becomes united 
 with it at the metacarpal joint. 
 
 The tendon of the middle usually receives a slip from that of 
 the ring-fiDger. The tendon of the ring finger generally sends a 
 slip to the tendons on either side of it, and in some cases entirely 
 furnishes the tendon of the little finger. 
 
 It is not only a general extensor of the fingers, but it can extend 
 some of the phalanges independently of the rest : e.g. it can extend 
 the first phalanges while the second and third are flexed ; or it can 
 extend the second and third phalanges during flexion of the first. 
 This long slender muscle, which is situated on the 
 inner side of the common extensor muscle, arises from 
 
 nimior the common tendon from the external condyle, and 
 from the septa between it and the contiguous muscles. 
 Its slender tendon runs beneath the annular ligament immedi- 
 ately behind the joint between the radius and ulna, in a special 
 sheath lined by synovial membrane. At the first joint of the little 
 finger, the tendon is joined by that of the common extensor, 
 and both expand upon the first and second phalanges, terminat- 
 ing in the same manner as the extensor tendons of the other 
 fingers. Its nerve comes from the posterior interosseus. 
 
 This muscle arises from the common tendon from 
 Extensor 
 
 carpi the external condyle, from the septum between it and 
 
 the extensor minimi digiti, and from the aponeurosis 
 
 of the forearm. The fibres terminate upon a strong broad tendon, 
 
 * The extensor tendons are only inserted into the periosteum, whereas the flexor 
 tendons are inserted into the substance of the bone. This accounts for the facility 
 with which the former will tear off the bones in cases of necrosis, while the latter will 
 adhere so tightly as to require cutting before the phalanx can be removed. 
 
DISSECTION OF THE BACK OF THE FORE ABM; 287 
 
 which traverses a distinct groove on the back of the ulna, close to 
 the styloid process, and is inserted into the carpal end of the 
 metacarpal bone of the little finger. Below the styloid process of 
 the ulna, the tendon passes beneath the posterior annular liga- 
 ment, over the back of the wrist, and is here contained in a very 
 strong fibrous canal, which is attached to the back of the cunei- 
 form, pisiform, and unciform bones, and is lined by a continuation 
 from the synovial membrane in the groove of the ulna. The 
 action of this muscle is to extend the hand, and incline it towards 
 the ulnar side. It is supplied by the posterior interosseous nerve. 
 In.pronation of the forearm, the lower end of the ulna* projects 
 between the tendons of the extensor carpi ulnaris and the extensor 
 minimi digiti. A subcutaneous bursa, is sometimes found above 
 the bone in this situation. 
 
 This small triangular muscle is situated at the outer 
 and back part of the elbow. It is covered by a strong 
 layer of fascia, derived from the tendon of the triceps, and appears 
 like a continuation of that muscle. It arises tendinous from the 
 posterior part of the external condyle of the humerus, and is 
 inserted into the triangular surface on the upper fourth of the 
 outer part of the ulna. Part of the under surface of the muscle 
 is in contact with the capsule of the elbow-joint. Its action is to 
 assist in extending the forearm. Its nerve comes from the 
 musculo-spiral. 
 
 To expose the deep layer of muscles, detach from the 
 external condyle, the extensor carpi radialis brevior, 
 
 the back of the extensor communis digitorum, the extensor minimi 
 digiti, and the extensor corpi ulnaris ; and after noticing 
 the vessels and nerves which enter their under surface, turn them 
 down. The deep-seated muscles, with the posterior interosseous 
 artery and nerve, must be cleaned. The muscles exposed are : 
 1. The extensor ossis metacarpi pollicis. 2. Extensor primi 
 internodii pollicis. 3. Extensor secundi internodii pollicis. 4. 
 Extensor indicis or indicator. 5. The supinator radii brevis. 
 They are all supplied by branches from the posterior interosseous 
 nerve. 
 
288 DISSECTION OF THE BACK OF THE FOREARM. 
 
 This muscle arises from the posterior surface of the 
 ossis meta- ulna below the supinator brevis, from the posterior 
 carpi pol- surface of the radius, and from the interosaeous liga- 
 ment. The muscle crosses the radial extensors of the 
 wrist about three inches above the carpus, and terminates in a 
 tendon, which passes along a groove, lined by synovial membrane, 
 on the outer part of the lower end of the radius, and is inserted 
 into the base of the metacarpal bone of the thumb, and frequently 
 also by a tendinous slip into the trapezium. 
 
 This muscle arises from the posterior surface of the 
 
 Jiixtensor A 
 
 primi in- radius and ulna, below the preceding, and from the inter- 
 ^md" osseous ligament. It turns over the radial extensors of 
 the wrist, and terminates upon a tendon which passes 
 beneath the annular ligament, through the groove on the outer 
 part of the radius, and is inserted into the radial side of the base 
 of the first phalanx of the thumb. 
 
 Extensor Arises from the posterior surface of the ulna, and 
 
 secundi inter- from the interosseous membrane. The tendon receives 
 nodn polhcis. fl es } iy fibres as low as the wrist, passes beneath the 
 annular ligament, in a distinct groove on the back of the radius, 
 crosses the tendons of the radial extensors of the wrist, proceeds 
 over the metacarpal bone and the first phalanx of the thumb, and 
 is inserted into the base of the last phalanx. 
 
 The tendons of the three extensors of the thumb may be easily 
 distinguished in one's own hand. The extensor ossis metacarpi, 
 and primi internodii pollicis, cross obliquely over the radial artery, 
 where it lies on the external lateral ligament of the carpus; the 
 extensor secundi internodii pollicis crosses the artery just before 
 it sinks into the palm, between the first and second metacarpal 
 bones, and is a good guide to the vessel. The action of the three 
 extensors of the thumb is implied by their names. 
 Extensor This musc ^ e Arises from the posterior surface of the 
 
 indicis, or ulna, and from the interosseous ligament. The tendon 
 passes beneath the posterior annular ligament, in the 
 same groove on the back of the radius with the tendons of the 
 extensor digitorum communis. It then proceeds over the back of 
 
DISSECTION OF THE BACK OF THE FOREARM. 289 
 
 the hand to the first phalanx of the index finger, where it is 
 united to the ulnar border of the common extensor tendon. By 
 the action of this muscle, the index finger can be extended inde- 
 pendently of the others. 
 
 Reflect the extensor carpi radialis longior and the anconeus 
 from their origins, to expose the following muscle. 
 
 This muscle embraces the upper third of the radius. 
 ^ arises from the external lateral ligament of the elbow- 
 joint, from the annular ligament surrounding the head 
 of the radius, from an oblique ridge on the outer surface of the 
 ulna below the insertion of the anconeus, and by fleshy fibres from 
 the triangular excavation below the lesser sigmoid notch of the 
 ulna. The muscular fibres turn over the neck and upper part of 
 the shaft of the radius, and are inserted into the upper third of 
 this bone, as far forwards as the ridge leading from the tubercle 
 to the insertion of the pronator teres. The muscle is perforated 
 obliquely by the posterior interosseous nerve, one of the terminal 
 divisions of the musculo-spiral nerve, and its upper part is in 
 contact with the capsule of the elbow-joint. It is a powerful 
 supinator of the forearm, some of its fibres acting at nearly a right 
 angle to the axis of the radius. 
 
 Posterior ^" s ar ^ er J comes from the ulnar by a common trunk 
 
 interosseous with the anterior interosseous (p. 254), and supplies the 
 artery. muscles on the back of the forearm. It passes between 
 
 the radius and ulna above the interosseous membrane, and appears 
 between the supinator radii brevis and the extensor ossis metacarpi 
 pollicis. After supplying branches to all the muscles in this 
 situation, the artery descends, much diminished in size, between 
 the superficial and deep layer of muscles to the wrist, where it 
 inosculates with the carpal branches of the anterior interosseous, 
 and the posterior carpal branches of the radial and ulnar arteries. 
 
 But the largest branch of this artery is the recurrent. It ascends 
 beneath the anconeus muscle to the space between the external 
 condyle and the olecranon, where it inosculates with the branch 
 of the superior profunda, which descends in the substance of the 
 triceps. 
 
290 DISSECTION OF THE BACK OF THE FOREAKM. 
 
 In the lower part of the back of the forearm, a branch of the 
 anterior interosseous artery is seen passing through the interosseous 
 membrane to reach the back of the wrist (see p. 254). 
 p . The nerve which supplies the muscles on the back of 
 
 interosseous the forearm is the posterior interosseous^ a branch of 
 nerve. ^ muscu l o _ S pi ra l. it passes obliquely through the 
 
 supinator radii brevis, and descends between the superficial and 
 deep layer of muscles on the back of the forearm, sending to each 
 a filament, generally in company with a branch of the posterior 
 interosseous artery. It sends a branch to the extensor carpi 
 radialis brevior, and supplies the supinator brevis in passing 
 through its substance. The supinator radii longus and the ex- 
 tensor carpi radialis longior are supplied by distinct branches from 
 the musculo- spiral. 
 
 The continuation of the posterior interosseous nerve descends 
 beneath the extensor secundi internodii pollicis and the tendons of 
 the extensor digitorum communis to the back of the wrist. Behind 
 the common extensor tendons the nerve forms a kind of gangliform 
 enlargement from which filaments are sent to the carpal and 
 metacarpal joints. 
 
 Trace the continuation of the radial artery over the 
 
 Kadial artery J 
 
 on the back external lateral ligament of the carpus, beneath the 
 of the wrist. ex tensor tendons of the thumb, to the upper part of the 
 interval between the first and second metacarpal bones, where it 
 sinks between the two origins of the abductor indicis, and entering 
 the palm, forms the deep palmar arch. In this part of its course 
 it is crossed by filaments of the radial nerve ; observe, also, that 
 the tendon of the extensor secundi internodii pollicis passes over 
 it immediately before it sinks into the palm. It supplies the 
 following small branches to the back of the hand: 
 
 a. Posterior carpal artery. This branch passes across the 
 carpal bones, beneath the extensor tendons. It inosculates with 
 the termination of the anterior interosseous artery, and with a 
 corresponding branch from the ulnar artery. The carpal artery 
 sends off small branches, called the dorsal interosseous, which 
 descend along the third and fourth interosseous spaces, beneath 
 
DISSECTION^ OF THE BACK'OF THE FOREARM. 291 
 
 the 'extensor tendons, inosculating near the carpal ends of the 
 metaearpal bones with the perforating branches from the deep 
 palmar arch. 
 
 6. The first dorsal interosseous artery is generally larger than 
 the others. It descends over the second interosseous muscle to 
 the cleft between the index and middle fingers, communicating 
 here with a perforating branch of the deep palmar arch, and 
 terminates in small branches, some of which proceed along the 
 back of the fingers, others inosculate with the palmar digital 
 arteries. 
 
 c. The dorsal artery of the index-finger, a branch of variable 
 size, passes over the first interosseous muscle to the radial side of 
 the back of the index finger. 
 
 d. The dorsal arteries of the thumb are two small branches 
 which arise from the radial opposite the head of the first meta- 
 carpal bone, and run along the back of the thumb, one on either 
 side. They are often absent. 
 
 These dorsal interosseous arteries supply the extensor tendons 
 and their sheaths, the interosseous muscles, and the skin on the 
 back of the hand, and the first phalanges of the fingers. 
 
 Kemove the tendons from the back and from the palin of the 
 hand : observe the deep palmar fascia which covers the interosseous 
 muscles. It is attached to the ridges of the metacarpal bones, 
 forms a distinct sheath for each interosseous muscle, and is con- 
 tinuous inferiorly with the transverse metacarpal ligament. On 
 the back of the hand the interosseous muscles are covered by a 
 thin fascia, which is attached to the adjacent borders of the meta- 
 carpal bones. 
 
 Transverse "^ s cons i s ts of strong bands of ligamentous fibres, 
 metacarpal which pass transversely between the digital extremities 
 ligament. o f t j ie me tacarpal bones. These bands are intimately 
 united to the fibro-cartilaginous ligament of the metacarpal joints, 
 and are of sufficient length to admit of a certain degree of move- 
 ment between the ends of the metacarpal bones. 
 
 Kemove the fascia which covers the interosseous muscles, and 
 separate the metacarpal bones by dividing the transverse meta- 
 
292 
 
 INTEROSSEOUS MUSCLES. 
 
 Interosseous 
 muscles. 
 
 carpal ligament. A bursa is frequently developed between their 
 digital extremities. 
 
 These muscles, so named from their position, extend 
 from the sides of the metacarpal bones to the bases of 
 the first phalanges and the extensor tendons of the 
 fingers. In each interosseous space (except the first, in which 
 there is only an abductor) there are two, one of which is an ab- 
 ductor, the other an adductor of a finger. According to this 
 arrangement there are seven in all; four of which, situated on the 
 back of the hand, are called dorsal ; the remainder, seen only in 
 the palm, are called palmar. 
 
 Fig. 53. 
 
 Fig. 54. 
 
 DIAGRAM OF THE FOUR DORSAL IN- 
 TEROSSEI, DRAWING FROM THE 
 MIDDLE LINE. 
 
 DIAGRAM OF THE THREE PALMAR IN- 
 TEROSSEI, AND ALSO THE ADDUCTOR 
 POLLICIS, DRAWING TOWARDS THE 
 MIDDLE LINE. 
 
 Each dorsal interosseous muscle arises from the 
 
 Dorsal opposite sides of two contiguous metacarpal bones 
 
 (fig. 53). From this double origin the fibres converge 
 
 to a tendon, which passes between the metacarpal joints of the 
 
 finger, and is inserted into the side of the base of the first phalanx ; 
 
INTEROSSEOUS MUSCLES. 293 
 
 it is also connected by a broad expansion with the extensor tendon 
 on the back of the finger. 
 
 The first dorsal interosseous muscle (abductor indicis) is larger 
 than the others^ and occupies the interval between the thumb and 
 fore-finger. It arises from the upper half of the ulnar side of the 
 first metacarpal bone, and from the entire length of the radial side 
 of the second : between the two origins, the radial artery passes 
 into the palm. Its fibres converge on either side to a tendon, 
 which is inserted into the radial side of the first phalanx of the 
 index finger and its extensor tendon. 
 
 The second dorsal interosseous muscle occupies the second meta- 
 carpal space. It is inserted into the radial side of the first phalanx 
 of the middle finger and its extensor tendon. 
 
 The third and fourth, occupying the corresponding metacarpal 
 spaces, are inserted, the one into the ulnar side of the middle, the 
 other into the ulnar side of the ring finger. 
 
 If an imaginary line be drawn longitudinally through the middle 
 finger, as represented by the dotted line in fig. 53, we shall find 
 that all the dorsal interosseous muscles are abductors from that 
 line; consequently, they separate the fingers from each other. 
 
 It requires a careful examination to distinguish this 
 f P m " se t of muscles, because the dorsal muscles protrude 
 with them into the palm. They are smaller than the 
 dorsal, and each arises from the lateral surface of only one meta- 
 carpal bone, that, namely, connected with the finger into which 
 the muscle is inserted (fig. 54). They terminate in small tendons, 
 which pass between the metacarpal joints of the fingers, and are 
 inserted, like the dorsal muscles, into the sides of the first phalanges 
 and the extensor tendons on the back of the fingers. 
 
 'The first palmar interosseous muscle arises from the ulnar side 
 of the second metacarpal bone, and is inserted into the ulnar side 
 of the index finger. The second and third arise, the one from the 
 radial side of the fourth, the other from the radial side of the fifth 
 metacarpal bone, and are inserted into the same sides of the ring 
 and little fingers. 
 
 The palmar interosseous muscles are all adductors to an imagi- 
 
294 
 
 LIGAMENTS OF THE CLAVICLE. 
 
 nary line drawn through the middle finger (fig. 54). They are, 
 therefore, the opponents of the dorsal interosseous muscles, and 
 move the fingers towards each other. 
 
 The palmar and dorsal interossei are supplied by offsets from 
 the deep branch of the ulnar nerve. 
 
 DISSECTION OP THE LIGAMENTS. 
 
 The inner end of the clavicle articulates with a shallow 
 excavation on the upper and outer part of the sternum. 
 The security of the joint depends upon the strength of 
 its ligaments. There are two synovial membranes, arid 
 an intervening fibre-cartilage. 
 The anterior sterno-clavicular ligament (fig. 55), consists of a 
 
 Fig. 55. 
 
 JOINT BE- 
 TWEEN THE 
 
 CLAVICLE 
 AND THE 
 
 STERNUM. 
 
 DIAGRAM OF THE STERNO-CLAVICULAE LIGAMENTS. 
 1. Interclavicnlar ligament. 3. Costo-clavicular ligament. 
 
 2. Anterior sterno-clavicular ligament. 
 
 4. Interarticular nbro-cartilage. 
 
 broad band of ligamentous fibres, which pass obliquely downwards 
 and inwards over the front of the joint, from the end of the clavicle 
 to the anterior surface of the sternum. 
 
 A similar band, the posterior sterno-clavicular ligament, ex- 
 tends over the back of the joint, from the back of the clavicle to 
 the back of the sternum. 
 
 The clavicles are connected by the inter-clavicular ligament. 
 It extends transversely above the notch of the sternum, and has a 
 
LIGAMENTS OF THE CLAVICLE. 295 
 
 broad attachment to the upper border of each clavicle. Between 
 the clavicles it is more or less attached to the sternum, so that it 
 forms a curve with the concavity upwards. 
 
 The three ligaments just described are so closely connected, that, 
 collectively, they form a complete fibrous capsule of great strength 
 for the joint. 
 
 A ligament, called the costo-davicular or rhomboid, connects 
 the clavicle to the cartilage of the first rib. It ascends from the 
 cartilage of the rib to a rough surface beneath the sternal end of 
 the clavicle. Its use is to limit the elevation of the clavicle. There 
 is such constant movement between the clavicle and the cartilage 
 of the first rib, that a well-marked bursa is commonly found 
 between them. 
 
 Liter articular fibro-cartilage. To see this, cut through the 
 rhomboid, the anterior and posterior ligaments of the joint, and 
 raise the clavicle. It is nearly circular in form, and thicker at 
 the circumference than the centre, in which there is sometimes a 
 perforation. Inferiorly, it is attached to the cartilage of the first 
 rib, close to the sternum ; superiorly, to the upper part of the 
 clavicle and the inter-clavicular ligament. Its circumference is 
 inseparably connected with the fibrous capsule of the joint. 
 
 The joint is provided with two synovial membranes : one between 
 the articular surface of the sternum and the inner surface of the 
 fibro-cartilage ; the other, between the articular surface of the 
 clavicle and the outer surface of the fibro-cartilage. 
 
 This interarticular fibro-cartilage is a structure highly elastic, 
 without admitting of any stretching. It equalises pressure, pre- 
 vents shocks, and also acts as a ligament, preventing the clavicle 
 from being driven inwards towards the mesial line. 
 
 Observe the relative form of the cartilaginous surfaces of the 
 bones : that of the sternum is slightly concave in the transverse, 
 and convex in the antero-posterior direction ; that of the clavicle 
 is the reverse. 
 
 The form of the articular surfaces and the ligaments of a joint 
 being known, it is easy to understand the movements of which it 
 is capable. The clavicle can move upon the sternum in a direction 
 
296 SHOULDER-JOINT. 
 
 either vertical or horizontal: thus it admits of circumduction. 
 These movements, though limited at the sternum, are considerable 
 at the apex of the shoulder. 
 
 The outer end of the clavicle articulates with the 
 OF THE CIA- acromion, and is connected by strong ligaments to the 
 VICLE WITH C oracoid process of the scapula. 
 
 THE SCAPULA. . . I . 7 . 7 7 mi 
 
 Joint between the acromion and the clavicle. The 
 clavicle and the acromion articulate with each other by two flat 
 oval cartilaginous surfaces, of which the planes slant inwards, and 
 the greater diameters are in the antero-posterior direction. 
 
 The superior ligament, a broad band of ligamentous fibre.s, 
 strengthened by the aponeurosis of the trapezius, extends from the 
 upper surface of the acromion to the upper surface of the clavicle. 
 
 The inferior ligament, of less strength, extends along the under 
 surface of the joint from bone to bone. 
 
 An interarticular Jibro-cartilage is sometimes found in this 
 joint : but it is incomplete, and seldom extends lower than the 
 upper half. There is only one synovial membrane. 
 
 Coraco-clavicular ligament. The clavicle is connected to the 
 coracoid process of the scapula by two strong ligaments the 
 conoid and trapezoid, which, being continuous with each other, 
 might fairly be considered as one. The trapezoid ligament is the 
 more anterior and external. It arises from the back part of the 
 coracoid process, and ascends obliquely outwards to the clavicle, 
 near its outer end. The conoid ligament is fixed at its apex to 
 the root of the coracoid process, ascends vertically, and is attached 
 by its base to the clavicle, near the posterior border. When the 
 clavicle is fractured in the line of the attachment of the coraco- 
 clavicular ligament, there is no displacement of the fractured ends ; 
 these being kept in place by the ligament. 
 
 Ligaments proper to the scapula. There are two : the coracoid 
 ligament, attached to the margins of the supra-scapular notch ; and 
 the coraco-acromial or triangular ligament, attached by its apex 
 to the acromion, and by its base to the outer border of the cora- 
 coid process. It is separated from the upper part of the capsule 
 of the shoulder-joint by a large bursa. 
 
SHOULDER-JOINT. 297 
 
 The articular surface of the head of the humerus, 
 f rmm g rather more than one-third of a sphere, moves 
 upon the shallow glenoid cavity of the scapula, which 
 is of an oval form, with the broader end downwards, and the long 
 diameter nearly vertical. The security of the joint depends, not 
 upon any mechanical contrivance of the bones, but upon the great 
 strength and number of the tendons which surround it. 
 
 To admit the free motion of the head of the humerus upon the 
 glenoid cavity, it is requisite that the capsular ligament of the 
 joint be loose and capacious. Accordingly, the head of the bone, 
 when detached from its muscular connections, may be separated 
 from the glenoid cavity to the extent of an inch, or more, without 
 laceration of the capsule. This explains the elongation of the arm 
 observed in some cases in which effusion takes place into the joint ; 
 also in cases of paralysis of the deltoid. 
 
 The capsular ligament is attached above, round the circum- 
 ference of the glenoid cavity ; and below, round the anatomical 
 neck of the humerus. It is strengthened on its upper and pos- 
 terior part by the tendons of the supra-spinatus, infra-spin attis, 
 and teres minor ; its inner part is strengthened by the broad tendon 
 of the subscapularis, its lower part by the long head of the triceps. 
 
 Thus the circumference of the capsule is surrounded by tendons 
 on every side, excepting a small space towards the axilla. If the 
 humerus be raised, it will be found that the head of the bone rests 
 upon this unprotected portion of the capsule between the tendons 
 of the subscapularis and the long head of the triceps : through this 
 part of the capsule the head of the bone usually protrudes in dis- 
 locations into the axilla. 
 
 At the upper and inner side of the joint, a small opening (fora- 
 men ovale) is observable in the capsular ligament, through which 
 the tendon of the subscapularis passes, and comes in contact with 
 the sy no vial membrane. 
 
 The upper surface of the capsule is strengthened by a strong 
 band of ligamentous fibres, called the cor aco -humeral or accessory 
 ligament. It is attached to the root of the coracoid process, 
 expands over the upper surface of the capsule, with which it is 
 
298 ELBOW-JOINT. 
 
 inseparably united, and is fixed into the greater tuberosity of the 
 humerus. 
 
 Open the capsule to see the tendon of the long head of the biceps. 
 It enters the joint through the groove between the two tuber osities, 
 becomes slightly flattened, and passes over the head of the bone to 
 be attached to the upper border of the glenoid cavity. It is loose 
 and movable within the joint ; and it acts like a strap, keeping down 
 the head of the bone. 
 
 The tendon of the biceps does not perforate the synovial mem- 
 brane of the joint. It is inclosed in a tubular sheath, which is 
 reflected over it at its attachment to the glenoid cavity, and 
 accompanies it for two inches down the groove of the humerus. 
 During the earlier part of foetal life it is connected to the capsule 
 by a fold of synovial membrane, which subsequently disappears. 
 
 The margin of the glenoid cavity of the scapula is surrounded 
 by a fibro-cartilaginous band of considerable thickness, called the 
 glenoid ligament. This not only enlarges but deepens the cavity. 
 Superiorly, it is continuous on either side with the tendon of the 
 biceps ; inferiorly, with the tendon of the triceps : in the rest of 
 its circumference it is attached to the edge of the cavity. 
 
 The cartilage covering the head of the humerus is thicker at 
 the centre than at the circumference. The reverse is the case in 
 the glenoid cavity. 
 
 The synovial membrane lining the under surface of the capsule 
 is reflected around the tendon of the biceps, and passes with it in 
 the form of a cul-de-sac, down the bicipital groove. On the inner 
 side of the joint it always communicates with the bursa beneath 
 the tendon of the subscapularis. 
 
 The shoulder-joint has a more extensive range of motion than 
 any other joint in the body ; it is, in fact, a universal joint. It is 
 capable of motion forwards and backwards ; of adduction, abduction, 
 circumduction, and rotation. 
 
 The elbow-joint is a perfect hinge. The larger sig- 
 moid cavity of the ulna is adapted to the trochlea upon 
 the lower end of the humerus, admitting of simple 
 flexion and extension ; while the shallow excavation upon the head 
 
ELBOW-JOINT. 
 
 299 
 
 of the radius admits not only of flexion and extension, but of rota- 
 tion upon the rounded articular eminence (capitellum) of the hu- 
 merus. The joint is secured by two strong lateral ligaments. No 
 ligament is attached to the head of the radius, otherwise its rotatory 
 movement would be impeded. It is simply surrounded by a liga- 
 mentous collar, called the annular ligament, within which it freely 
 rolls. 
 
 Internal lateral ligament. This is triangular. Its apex is 
 attached to the internal condyle of the humerus : from this point 
 the fibres radiate, and are inserted into the greater sigmoid cavity 
 of the ulna. 
 
 A transverse band of ligamentous fibres extends from the ole- 
 cranon to the coronoid process across a notch observable on the 
 inner side of the sigmoid cavity : through this notch vessels pass 
 into the joint. 
 
 External lateral ligament. This is attached to the external 
 
 Fig. 56. 
 
 a 
 
 a. External lateral ligament. 
 ft. Orbicular ligament. 
 
 c. Internal lateral ligament. 
 
 <?. Radius, removed from its ring. 
 
 LIGAMENTS OP THE ELBOW. 
 
 condyle of the humerus ; the fibres spread out as they descend, and 
 are interwoven with the annular ligament, surrounding the head 
 of the radius. 
 
300 ELBOW-JOINT. 
 
 The anterior and posterior ligaments of the elbow-joint consist 
 merely of a few thin ligamentous fibres spread over the capsule of 
 the joint in front and behind. There is no need of ligaments to 
 limit flexion and extension in this joint : for the coronoid process 
 limits the one ; the olecranon the other. 
 
 The preceding ligaments, collectively, form a continuous capsule 
 for the joint. 
 
 The orbicular or annular ligament of the radius (fig. 56) is 
 attached to the anterior and the posterior border of the lesser 
 sigmoid cavity of the ulna. With this cavity, it forms a complete 
 collar, which encircles the head and part of the neck of the radius. 
 The lower part of the collar is narrower than the upper, in order 
 to clasp the neck of the radius, and maintain it more accurately in 
 position. 
 
 Synovial membrane of the elbow-joint. Open the joint by a 
 transverse incision in front, and observe the relative adaptation of 
 the cartilaginous surfaces of the bones. The synovial membrane 
 lines the interior of the capsule, and forms a cul-de-sac between 
 the head of the radius and its orbicular ligament. It is widest 
 and loosest under the tendon of the triceps. Where the mem- 
 brane is reflected from the bones upon the ligaments, there is 
 more or less adipose tissue, particularly in the fossae on the front 
 and back part of the lower end of the humerus. 
 Interosseous ^is * s an a P neur tic septum, stretched between 
 ligament or the bones of the forearm, of which the chief purpose is 
 
 i rane. j. Q a ff or( j an i ncrease o f surface for the attachment of 
 muscles. The septum is deficient above, to permit free rotation 
 of the radius. Its fibres extend obliquely downwards from the 
 radius to the ulna. It is perforated in its lower third by the 
 anterior interosseous vessels. 
 
 The name of round or oblique ligament is given to a thin band 
 of ligamentous fibres, which extends obliquely between the bones 
 of the forearm in a direction contrary to those of the interosseous 
 membrane. It is attached, superiorly, to the front surface of the 
 ulna, near the outer side of the coronoid process ; inferiorly, to the 
 radius immediately below the tubercle. Between this ligament 
 
WRIST-JOINT. 301 
 
 and the upper border of the interosseous membrane is a triangular 
 interval through which the posterior interosseous artery passes to 
 reach the back of the forearm. A bursa intervenes between the 
 oblique ligament and the insertion of the tendon of the biceps. 
 The use of this ligament is to limit supination of the radius. 
 EADIO-CAR- ^ n * s J^ n * * s f rme( i by the lower end of the radius, 
 PAL OB which articulates with the scaphoid and semilunar bones 
 WBIST JOINT. Q f fa e car p us . the i ower eiic i O f the ulna is excluded 
 from the joint by a triangular fibre-cartilage, which articulates 
 with a small portion of the cuneiform bone. The joint is secured 
 by an anterior, a posterior, and two lateral ligaments, forming, 
 together, an uninterrupted capsule around it. 
 
 The external lateral ligament extends from the styloid process 
 of the radius, to the scaphoid bone and the anterior annular 
 ligament (p. 302). 
 
 The internal lateral ligament proceeds from the extremity of 
 the styloid process of the ulna, to the cuneiform bone. Some of 
 its fibres are attached to the pisiform bone, and the anterior annu- 
 lar ligament. 
 
 The anterior ligament consists of two or more broad bands of 
 ligamentous fibres, which extend from the lower end of the radius, 
 to the first row of carpal bones. 
 
 The posterior ligament, weaker than the preceding, proceeds 
 from the posterior surface of the lower end of the radius, and is 
 attached to the posterior surfaces of the first row of carpal bones. 
 
 The synovial membrane lines the under aspect of the triangu- 
 lar fibro-cartilage at the end of the ulna, is reflected over the 
 several ligaments of the joint, and thence upon the first row of 
 the carpal bones. 
 
 JOINT BE- r -T ne inner surface of the lower end of the radius 
 TWEEN THE presents a slight concavity, which rotates upon the 
 OF THE RA- convex head of the ulna : this mechanism is essential 
 
 
 AND to the pronation and supination of the hand. These 
 corresponding surfaces are crusted with a thin layer of 
 cartilage, and are provided with a very loose synovial membrane. 
 The joint is strengthened in front and behind by a thin transverse 
 
302 
 
 WRIST-JOINT. 
 
 ligament, which extends from the anterior and posterior borders 
 of the sigmoid cavity of the radius, to the anterior and posterior 
 surfaces of the styloid process of the ulna. But the principal 
 uniting medium between the bones is a strong nbro-cartilage. 
 
 Fibro-cartilage between the radius and ulna. Saw through 
 the bones of the forearm, and separate them by cutting through 
 the interosseous membrane, and opening the synovial membrane 
 of the joint between the lower ends. Thus a good view is ob- 
 
 Fig. 57. 
 
 1. External lateral ligament. 
 
 2. Internal lateral ligament. 
 
 3. Interarticular fibro-car- 
 
 tilage. 
 
 4. Interosseous liga- 
 ments. 
 
 5. Lateral ligaments of 
 the intercarpal joint. 
 
 DIAGBAM OF THE WHIST-JOINT. 
 
 tained of the nbro-cartilage which connects them (fig. 57) It is 
 triangular, and placed transversely at the lower end of the 
 ulna, filling up the interval caused by the greater length of the 
 radius. Its base is attached to the lower end of the radius, and 
 its apex to the root of the styloid process of the ulna. It is thin 
 at the base and the centre, thicker at the apex and the sides. Its 
 upper surface is in contact with the ulna, and covered by the 
 synovial membrane of the radio-ulnar joint; its lower surface, 
 
CARPAL BONES. 303 
 
 forming a part of the wrist-joint, corresponds to the cuneiform 
 bone. Its borders are connected with the anterior and posterior 
 ligaments of the wrist. In some instances there is an aperture in 
 the centre. 
 
 When, from accident or disease, this fibro-cartilage gets de- 
 tached from the radius, the consequence is a preternatural projec- 
 tion of the lower end of the nlna. 
 
 The synovial membrane of this joint is distinct from that of the 
 wrist, except in the case of a perforation through the fibro-carti- 
 lage. On account of its great looseness, necessary for the free 
 rotation of the radius, it is called ' membrana sacciformis.' 
 CONNECTION The bones of the carpus are arranged in two rows, an 
 OF THE CAR- U pp er an d a lower, adapted to each other, so as to form 
 
 PAL BONES * r C 
 
 WITH EACH between them a joint, connected by anterior, posterior, 
 OTHER. internal, and external lateral ligaments. 
 
 The bones, constituting each row, are united by ligaments placed 
 on their palmar and dorsal surfaces, and by others, placed between 
 the bones, and hence called interosseous. Their contiguous sur- 
 faces (those of the pisiform and cuneiform excepted) are covered 
 by the reflections of one synovial membrane. 
 
 The upper row is united by transverse ligaments proceeding 
 from the scaphoid to the semilunar bone, and from the semilunar 
 to the cuneiform, both on their dorsal and palmar surfaces : also 
 by interosseous ligaments, proceeding from the semilunar to the 
 bones on either side of it (fig. 57). 
 
 The pisiform bone is articulated to the palmar surface of the 
 cuneiform bone, to which it is united by a fibrous capsule. In- 
 feriorly it is attached by two strong ligaments, the one to the 
 unciform bone, the other to the carpal end of the fifth metacarpal 
 bone. This articulation has a distinct synovial membrane. 
 
 The lower row of carpal bones is connected in the same way as 
 the upper. The dorsal and palmar ligaments pass transversely 
 from one to the other. There are only two interosseous ligaments, 
 one on either side of the os magnum ; they are thicker and stronger 
 than those of the upper row, and unite the bones more firmly to- 
 gether (fig. 57). 
 
304 INTERCARPAL JOINT. 
 
 The upper row of carpal bones is arranged in the 
 f rm f an arch, s@v-as to receive the corresponding con- 
 vex surfaces of the os magnum and unciforme. Ex- 
 ternally to the os magnum, the trapezium and trapezoid bones 
 present a slightly concave surface, which articulates with the 
 scaphoid. In this way a joint capable of flexion and extension 
 only is formed between the upper and lower row. It is secured by 
 anterior, posterior, and two lateral ligaments. The anterior liga- 
 ment consists of strong ligarnentous fibres, which pass obliquely 
 from the bones of the upper to those of the lower row. The pos- 
 terior ligament consists of oblique and transverse fibres, which 
 connect the dorsal surfaces of the bones of the upper with the 
 lower row. 
 
 The lateral ligaments connect, externally, the scaphoid and 
 trapezium ; internally, the cuneiform and unciform bones (fig. 57). 
 Divide the ligaments, to see the manner in which the carpal 
 bones articulate with each other. Their surfaces are crusted with 
 cartilage, and have a common synovial membrane. This mem- 
 brane extends, superiorly, between the three bones of the upper 
 row, so as to form two culs-de-sac ; inferiorly, it is prolonged into 
 the joint between the carpal and the second and third metacarpal 
 bones. 
 
 , The trapezium presents a cartilaginous surface, con- 
 
 TWEEN TKA- vex in the transverse, and concave in the anterior 
 THE 1U rmsT D P os t er ior direction (i.e. saddle-shaped), which articu- 
 METACARPAL lates with a cartilaginous surface on the metacarpal 
 bone of the thumb, concave and convex in the opposite 
 directions. This peculiar adaptation of the two surfaces permits 
 the several movements of the thumb, viz., flexion, extension, 
 abduction and adduction ; consequently circumduction. Thus we 
 are enabled to oppose the thumb to all the fingers. The joint is 
 surrounded by a fibrous capsule sufficiently loose to admit free 
 motion, and stronger on the dorsal than on the palmar aspect. 
 The security of the joint is increased by the muscles which 
 surround it. It has a separate synovial membrane. 
 
METACARPAL JOINTS. 305 
 
 CARPO The me tacarpal bones of the fingers are connected to 
 
 METACAKPAL the second row of the carpal bones by ligaments upon 
 rTS< their palmar and dorsal surfaces. 
 
 The dorsal ligaments are the stronger. The metacarpal bone 
 of the fore-finger has two ; one from the trapezium, another from 
 the trapezoid bone. That of the middle finger has also two, pro- 
 ceeding from the os magnum, and the os trapezoides. That of the 
 ring finger has also two, proceeding from the os magnum, and the 
 unciform bone. That of the little finger has one only, from the 
 unciform bone. 
 
 The palmar ligaments are arranged nearly upon a similar plan. 
 The metacarpal bone of the fore-finger has one, from the trapezoid 
 bone. That of the middle finger has three, proceeding from the 
 tapezium, the os magnum, and the unciform bone. Those of the 
 ring and little fingers have each one, from the unciform bone. 
 
 Besides the preceding ligaments, there is another of considerable 
 strength, called the interosseous. It proceeds from the adjacent sides 
 of the os magnum and the os unciforme, descends vertically, and 
 is fixed into the radial side of the metacarpal bone of the ring 
 finger (fig. 57). This ligament isolates the synovial membrane of 
 the two inner metacarpal bones from the common synovial mem- 
 brane of the carpus. 
 
 Separate the metacarpal bones from the carpus, and observe the 
 relative form of their contiguous surfaces. The metacarpal bones 
 of the fore and middle fingers are adapted to the carpus in such 
 an angular manner as to be almost immovable. The metacarpal 
 bone of the ring finger, having a plane articular surface with the 
 unciform bone, admits of more motion. But still greater motion 
 is permitted between the unciform and the metacarpal bone of 
 the little finger ; the articular surfaces of each being slightly con- 
 cave and convex in opposite directions. The greater freedom of 
 motion of the metacarpal bone of the little finger is essential to 
 the expansion and contraction of the palm. 
 
 The carpal extremities of the metacarpal bones of the fingers 
 are connected with each other by transverse ligaments, both on 
 their dorsal and their palmar surfaces. They are also connected 
 
 x 
 
306 JOINTS OF THE FINGEKS. 
 
 by interosseous ligaments, which extend between the bones, imme- 
 diately below their contiguous cartilaginous surfaces. 
 
 The digital extremities of these bones are loosely connected on 
 their palmar aspect by the transverse metacarpal ligament. 
 
 There are six distinct synovial membranes, proper to 
 MEMBRANES the lower end of the radius, and the several bones of 
 or THE the carpus : see the diagram (p. 302). 
 
 a. One between the lower end of the radius and the 
 ulna. 
 
 6. One between the radius and the first row of carpal bones. 
 
 c. One between the trapezium and the metacarpal bone of the 
 
 thumb. 
 
 d. One between the cuneiform and pisiform bones. 
 
 e. One between the first and second rows of carpal bones (the 
 
 intercarpal joint). This extends to the metacarpal bones 
 of the fore and middle fingers. 
 
 /. One between the unciform bone and the metacarpal bones of 
 the little and ring fingers. 
 
 The first phalanx of the finger presents a shallow 
 or THE oval cavity, crusted with cartilage, with the broad 
 FINGERS. diameter in the transverse direction, to articulate with 
 the round cartilaginous head of the metacarpal bone, of which the 
 articular surface is elongated in the antero-posterior direction, 
 and of greater extent on its palmar than its dorsal aspect. This 
 formation of parts permits flexion of the finger to a greater degree 
 than extension ; and also a slight lateral movement. 
 
 Each joint is provided with two strong lateral, and a palmar or 
 glenoid ligament. 
 
 The lateral ligaments arise from the tubercles on either side of 
 each metacarpal bone, and inclining slightly forward, are inserted 
 into the sides of the base of the first phalanx of the finger. 
 
 The palmar or glenoid ligament. This is a thick, compact, 
 fibro-cartilagmous structure, which extends over the palmar surface 
 of the joint. Its lower end is firmly attached to the base of the 
 first phalanx of the finger ; its upper end is loosely adherent to 
 the rough surface above the head of the metacarpal bone. On 
 
JOINTS OF THE FINGERS. 307 
 
 either side it is inseparably connected with the lateral ligaments, so 
 that with them it forms a strong capsule over the front and sides 
 of the joint. Its superficial surface is slightly grooved, to receive 
 the flexor tendons ; its' deep surface is adapted to cover the head of 
 the metacarpal bone. Two sesamoid bones are found in the glenoid 
 ligament belonging to the joint between the metacarpal bone and 
 the first phalanx of the thumb. 
 
 The glenoid ligaments have a surgical importance for the follow- 
 ing reason : In dislocation of the fingers, the facility of reduction 
 mainly depends upon the extent to which the glenoid ligament is 
 injured. If it be much torn there is but little difficulty : if entire, 
 the reduction is tedious and sometimes impracticable. 
 
 These joints are secured on their dorsal aspect by the extensor 
 tendon, and the expansion proceeding from it on either side. Their 
 synovial membranes are loose, especially beneath the extensor 
 tendons. 
 
 The corresponding articular surfaces of the phalanges 
 SECOND AND . 
 
 LAST JOINT o* the fingers and thumb are so shaped as to torm a 
 
 or THE hinge-joint, and, therefore, incapable of lateral move- 
 
 ment. The ligaments connecting them are similar in 
 every respect to those between the metacarpal bones and the first 
 phalanges. The glenoid ligament of the last joint of the thumb 
 generally contains a sesamoid bone. 
 
 \ -2 
 
308 
 
 THE ABDOMEN. 
 
 Fig. 58. 
 
 DISSECTION OF THE ABDOMEN. 
 
 . , . We divide the abdomen into arbitrary regions, that 
 
 division into the situation of the viscera contained in it may be more 
 regions. easily described. For this purpose we draw the fol- 
 lowing imaginary lines : one horizontal across the abdomen on a 
 level with the cartilages of the ninth ribs ; another on a level with 
 the anterior spines of the ilia. These lines form the boundaries 
 
 of three spaces, each of which is sub- 
 divided into three regions by a vertical 
 line drawn on each side from the carti- 
 lage of the eighth rib to the middle of 
 Poupart's ligament. Thus, we have a 
 central and two lateral regions in each 
 space. The central region of the upper 
 space is termed the epigastric or scro- 
 biculus cordis, the central one of the 
 middle space is called the umbilical 
 region, and the central of the inferior 
 space, the hypogastric region. The 
 lateral regions of the spaces from above 
 downwards are termed the right and 
 left hypochondriac, the right and left 
 lumbar^ and the right and left inguinal 
 or iliac regions, respectively. 
 
 The abdomen should be distended with air, by means of a blow- 
 pipe inserted into the abdominal cavity at the umbilicus. 
 
 An incision should be made from the sternum to the pubes, 
 another from the anterior spine of the ilium to a point midway 
 between the umbilicus and pubes, and a third from the ensiform 
 cartilage, transversely outwards towards the axilla as far as the 
 
SUPERFICIAL VESSELS OF THE GROIN. 309 
 
 angles of the ribs. The skin should then be dissected from the 
 subjacent adipose and areolar tissue, called the ' superficial fascia.' 
 The subcutaneous tissue of the abdomen presents the 
 same general characters as that of other parts, and 
 varies in thickness in different individuals. At the 
 lower part of the abdomen, it admits of separation into two layers, 
 between which are found the subcutaneous blood vessels, the 
 absorbent glands, the ilio-inguinal nerve, and the hypogastric 
 branch of the ilio-hypogastric nerve. 
 
 Respecting the superficial layer, observe that it contains the fat, 
 and is continuous with the superficial fascia of the thigh, the 
 scrotum, and the perineum. The deeper layer is intimately con- 
 nected with Poupart's ligament and the linea alba ; but it is very 
 loosely continued over the spermatic cord and the scrotum, and 
 becomes identified with the deep layer of the superficial fascia of 
 the perineum. These points deserve attention, since they explain 
 how urine, extra vasated into the perineum and scrotum, readily 
 makes its way over the spermatic cord on to the surface of the ab- 
 domen ; but from this it cannot travel down the thigh, on account 
 of the connection of the fascia with Poupart's ligament. 
 Superficial Between the layers of the superficial fascia on the 
 blood-vessels groin and upper part of the thigh, are several absorbent 
 and glands. glandg and gmall blood vesse i s (fig. 59). The glands 
 
 are named, according to their situation, inguinal and femoral. 
 The inguinal, from three to four in number, are often small, and 
 escape observation. They are of an oval form, with their long 
 axis corresponding to the line of the crural arch (represented by 
 the dark line in fig. 59). They receive the absorbents from the 
 lower part of the wall of the abdomen, from the scrotum and 
 penis, and are therefore generally affected in venereal disease. 
 The lymphatics from the upper part of the abdominal parietes 
 terminate in the lumbar glands. 
 
 The superficial arteries in the neighbourhood arise from the 
 femoral. One, the epigastric, ascends over Poupart's ligament and 
 ramifies over the lower part of the abdomen, inosculating with the 
 deep epigastric artery ; another, the pudic, crosses the spermatic 
 
310 
 
 SUPERFICIAL VESSELS OF THE GROIN. 
 
 cord, and is distributed to the skin of the penis and scrotum ; a 
 third, the circumflexa ilii, ramifies towards the spine of the ilium. 
 These subcutaneous arteries, the pudic especially, often occasion a 
 free haemorrhage in the operation for strangulated hernia. 
 
 The corresponding veins join the saphena vein of the thigh. 
 Under ordinary circumstances they do not appear in the living sub- 
 Fig. 59. 
 
 SUPERFICIAL VESSELS AND GLANDS OF THE GROIN. 
 
 1. Saphenous opening of the fascia lata. 
 
 2. Saphena vein. 
 
 3. Superficial epigastric a. 
 
 4. Superficial circumflexa ilii a. 
 
 5. Superficial pudic a. 
 
 6. External abdominal ring. 
 
 7. Fascia lata of the thigh. 
 
 ject; but, when any obstruction occurs in the inferior vena cava, they 
 become enlarged and tortuous, and constitute the chief channels 
 through which the blood would be returned from the lower limbs.* 
 
 * A cast, in illustration of this, is preserved in the Museum of St. Bartholomew's 
 Hospital. 
 
ABDOMINAL MUSCLES. 311 
 
 The skin of the abdomen is supplied with nerves after 
 >us th 
 
 nerves. 
 
 Cutaneous ^ e game plan ag the cnest . name ly, by lateral and 
 
 anterior branches derived from the lower intercostal 
 nerves. 
 
 a. The lateral cutaneous nerves come out between the digita- 
 tions of the external oblique muscle, in company with small 
 arteries, and divide into anterior and posterior branches; the 
 anterior supply the skin as far as the rectus ; the posterior, the skin 
 over the latissimus dorsi. Observe, that the lateral branch of the 
 twelfth dorsal nerve is larger than the others, and that it passes 
 over the crest of the ilium to the skin of the buttock. The cor- 
 responding branch of the first lumbar has a similar distribution. 
 
 6. The anterior cutaneous nerves come with small arteries 
 through the sheath of the rectus. They are not only smaller than 
 the lateral nerves, but their number and place of exit is less 
 regular. That which comes through the external abdominal ring 
 (ilio-inguinal), as well as that which comes through the wall of 
 the abdomen just above it (the hypogastric branch of the ilio- 
 hypogastric), are derived from the first lumbar nerve. These, 
 however, are but repetitions of the others, and supply the skin of 
 the groin and scrotum in the male, and the labium pudendi of the 
 female.* 
 
 The deep layer of the superficial fascia should now be removed 
 from the external oblique, by commencing at the fleshy portion of 
 the muscle, and working in the course of its fibres. Care must be 
 taken not to remove any of its aponeurosis, which is very thin. 
 The digitations of this muscle with the serratus magnus and latis- 
 simus dorsi must also be made out. 
 
 Muscles of f ^ ie abdominal muscles, three on each side, are 
 the abdomi- arranged in strata, named, after the direction of their 
 nalwall. fibres? the < externa i oblique,' 'internal oblique,' and 
 ' transversalis.' They terminate in front in strong aponeuroses, 
 arranged so as to form a sheath for a broad muscle, called the 
 
 * A third small nerve, namely, the genital branch of the genito-crural, comes through 
 the external ring. It lies behind the cord close to the outer pillar. 
 
312 ABDOMINAL MUSCLES. 
 
 ' rectus,' which extends perpendicularly on each side the linea alba 
 from the sternum to the pubes (fig. 60, p. 314). 
 
 This muscle arises from the eight or nine lower ribs, 
 ^7 as many pointed bundles, called ' digitations.' The 
 upper five of these fit in with similar bundles of the 
 serratus magnus, and are obvious during life ; the three lower cor- 
 respond in like manner with the origin of the latissinms dorsi ; but 
 they cannot be seen unless the body be turned on the side. The 
 upper part of this muscle descends obliquely forwards, and ter- 
 minates on the aponeurosis of the abdomen ; the lower proceeds 
 almost perpendicularly from the last ribs, and is inserted into the 
 outer lip of the anterior two-thirds of the crest of the ilium.* 
 
 The aponeurosis of the external oblique increases in strength, 
 breadth, and thickness, as it approaches the lower margin of the 
 abdomen, this being the situation where the greater pressure of 
 the viscera requires the most effective support. Its tendinous 
 fibres take the same direction as the muscle, and form the ' linea 
 alba? by their decussation in the middle line from the ensiform 
 cartilage to the pubes. 
 
 Along the line of junction of the abdomen with the 
 
 Poupart's * 
 
 ligament or thigh, the aponeurosis extends from the anterior spine 
 crural arch. Q ^e ilium to the spine of the pubes, and forms an 
 arch over the intermediate bony excavation (p. 317). This, which 
 is termed the crural arch, or, more commonly, Pouparfs liga- 
 ment^ transmits the great vessels of the thigh, with muscles and 
 nerves. Near the pubes is an opening in the aponeurosis for the 
 passage of the spermatic cord in the male, and the round ligament 
 in the female. It is called the ( external abdominal ring.' Of 
 this, as well as of the crural arch, you must postpone the more 
 particular examination till the dissection of the parts concerned in 
 inguinal hernia. The external oblique should be carefully detached 
 
 * Prom its position and the direction of its fibres, it is manifest that the external 
 oblique represents, in the abdomen, the external intercostal muscles of the chest. 
 
 f This was first described by Fallopius, an Italian anatomist, in his ' Observationes 
 Anatomicse,' published in 1561. It was subsequently described by Poupart in 1705, 
 in the 'Mem. de 1'Acad. de Paris,' and is now commonly called 'Poupart's ligament.' 
 
ABDOMINAL MUSCLES. 313 
 
 from the ribs and the crest of the ilium, and turned forwards as 
 far as this can be done without injuring its aponeurosis or the 
 crural arch. The second muscular stratum will thus be exposed, 
 and recognised by the difference in the direction of its fibres which 
 pass upwards and inwards. 
 
 This muscle arises from the outer half of the crural 
 Internal arch, from the anterior two-thirds of the middle lip of 
 
 oblique. A 
 
 the crest of the ilium, and from the fascia lumborum. 
 The fibres ascend obliquely, and are inserted partly into the 
 abdominal aponeurosis, partly into the cartilages of the three or 
 four lower ribs.* 
 
 The internal oblique should be detached from the ribs, and from 
 the crest of the ilium, and turned forwards ; but that portion of it 
 connected to the crural arch must not be disturbed. In removing 
 the internal oblique, we are apt to cut away the transversalis. To 
 avoid this mistake, dissect near the crest of the ilium, and endeavour 
 to find an artery which- runs between the muscles, and serves as a 
 guide. This artery, called the deep c circumflexa iliij proceeds 
 from the external iliac, and supplies the abdominal muscles. Be- 
 neath the internal oblique the continuations of the intercostal nerves 
 and vessels are brought into view. These must be preserved. 
 
 This muscle arises from the outer third of the crural 
 
 Transversalis. ..'.-- . 
 
 arch, from the anterior two-thirds of the crest of the 
 ilium, from a fascia attached to the transverse processes of the 
 lumbar vertebrae, and, lastly, from the inner surfaces of the six or 
 seven lower costal cartilages, by digitations which correspond with 
 those of the diaphragm. From this origin the fibres proceed hori- 
 zontally forwards, and terminate in the abdominal aponeurosis. 
 Some of its fibres arch downwards, and are attached conjointly with 
 fibres of the internal oblique into the pubes. 
 Rectus ^is musc l e li es perpendicularly along the front of 
 
 the abdomen, and is enclosed in a sheath formed by the 
 aponeuroses of the lateral muscles of the abdomen. To expose it, 
 therefore, slit up its sheath along the middle, and reflect the two 
 
 * The internal oblique represents in the abdomen the internal intercostal muscles 
 of the chest. 
 
314 
 
 ABDOMINAL MUSCLES. 
 
 halves. It arises by two tendons, the inner of which is attached to 
 the symphysis, the outer, to the crest of the pubes. It is inserted 
 into the fifth, sixth, and seventh costal cartilages. Notice the 
 tendinous intersections across the muscle called ' linece transversce,' 
 which are only incomplete repetitions of the ribs in the wall of the 
 abdomen.*" Their number varies from three to five, but there are 
 always more above than below the umbilicus. These tendinous 
 intersections adhere closely to the sheath in front, but not behind ; 
 consequently, matter formed between the front of the rectus and 
 its sheath would be confined by two intersections ; not so on the 
 back of the muscle, for matter might travel down the entire length 
 of it. 
 
 The sheath of the rectus is composed in front by the aponeurosis 
 ;p ig 60 of the external oblique, 
 
 and half the thick- 
 ness of that of the in- 
 ternal oblique ; f while 
 the back of the sheath 
 comprises the aponeu- 
 rosis of the transversa- 
 lis, and the other half 
 of the internal oblique 
 (fig. 60). This, however, 
 applies only to the up- 
 per three- fourths of the 
 muscle; the lower fourth 
 THE has no sheath behind, 
 for all the aponeuroses 
 pass in front of it. 
 
 . This small triangular muscle is situated near the 
 
 pubes, close to the linea alba, and has a sheath of its 
 
 own. It arises from the upper part of the pubes in front of the 
 
 rectus, and terminates in the linea alba about midway between the 
 
 * Som'e animals e.g. the crocodile have bony abdominal ribs, 
 f The line where the internal oblique splits namely, along the outer border of the 
 rectus is called the linea semilunaris. 
 
 ERECTOR SP 
 DIAGRAM OF 
 
 TRANSVERSE SECTION THROUGH 
 ABDOMINAL MUSCLES. 
 
ABDOMINAL MUSCLES. 315 
 
 pubes and the umbilicus. It is said to be of use in tightening the 
 linea alba, but it does not appear to have any special purpose 
 in the human subject, for it is sometimes deficient on one or even 
 both sides. 
 
 Along the middle line of the abdomen the several 
 aponeuroses decussate so as to form a white tendinous 
 line extending from the sternum to the pubes. This is the ' linea 
 alba : ' it is but a continuation of the sternum deprived of its 
 earthy matter, in adaptation to the functions of this part of the 
 body. A little below the middle of it, is situated what was in the 
 foetus the opening for the passage of the umbilical vessels. After 
 birth, the vessels being no longer required, the opening gradually 
 closes, and becomes plugged by their fibrous remains. 
 
 Since the linea alba is the thinnest part of the abdomen, and is 
 free from blood vessels, it is chosen as a safe line for tapping in 
 dropsy, and for puncturing the bladder in retention of urine. 
 
 By dividing the rectus transversely near the umbilicus, and 
 raising it from its position, we have a complete view of the manner 
 in which the sheath is formed ; we observe, too, that this is very 
 indistinct behind the lower fourth of the muscle. Eamifying in 
 the substance of the muscle is a large artery, called the ' epigastric,' 
 a branch of the external iliac ; also the continuation of the internal 
 mammary, which descends from the subclavian. 
 Nerves of the T ese nerves are the continuations of the six lower 
 abdominal intercostal nerves, and of the first lumbar. They have 
 wall> the same general course and distribution. They run 
 
 forwards between the internal oblique and transversalis towards 
 the rectus. They furnish branches to the abdominal muscles, 
 and each gives off its lateral and anterior cutaneous branches, 
 described p. 311. 
 
 . f In consequence of their stratified arrangement, and 
 
 abdominal the different direction of their fibres, the abdominal 
 muscles. musc les answer many important purposes: 1. The 
 abdominal muscles maintain a gentle but effective pressure upon 
 the viscera, and serve to shield them from injury. The pressure is 
 proved by the fact that the bowels are almost sure to protrude 
 
316 PARTS CONCERNED IN INGUINAL HERNIA. 
 
 through a wound of the abdominal wall. The protection is proved 
 by the hard blow which the abdomen will stand provided its muscles 
 are on their guard ; 2. They are the principal muscles concerned 
 in forcible expiration ; 3. By compressing the viscera in conjunction 
 with the diaphragm, they are the chief agents in the expulsion of 
 the faeces and urine, also in vomiting, sneezing, laughing, cough- 
 ing ; 4. They act, each in its own way, as movers of the trunk ; 
 e. g. the right external oblique, co-operating with the left internal 
 oblique, can draw the trunk towards the left side, and vice versa. 
 The recti raise the body from the horizontal position, as any one 
 may ascertain by laying the hand on the abdomen while rising 
 from the ground. 
 
 EXAMINATION OF THE PARTS CONCERNED IN INGUINAL HERNIA. 
 
 "X. 
 
 General idea Having proceeded so far in the examination of the 
 of the sub- abdominal wall, now turn your attention to the anatomy 
 J 60 ' of the parts concerned in inguinal hernia. 
 
 The testicle, originally formed in the loins, passes, about the 
 eighth month of foetal life, from the abdomen into the scrotum, 
 through an oblique canal in the wall of the abdomen, called the 
 ' inguinal canal. 1 A portion of peritoneum is pouched out before 
 the testicle, and constitutes the tunica vaginalis testis. The blood 
 vessels, nerves, and excretory duct are drawn down after the 
 testicle and form the spermatic cord. The inguinal canal is 
 valvular and runs obliquely, so that the abdominal wall may the 
 better resist protrusion of the viscera. 
 
 The wall of the abdomen, as previously stated, is composed of 
 strata of different structures, and we shall presently find that the 
 spermatic cord, as it passes through each stratum, derives from 
 each a covering similar in structure to the stratum itself. Of these 
 strata there are three : the first that is, the aponeurosis of the 
 external oblique is called the ' aponeurotic stratum ; ' the second 
 that is, the internal oblique and transversalis muscles is called the 
 ' muscular stratum ; * the third namely, the fascia transversalis, 
 
PARTS CONCERNED IN INGUINAL HERNIA. 
 
 317 
 
 which lines the under aspect of the transversalis muscle is called 
 the ' fascial stratum.' The most intelligible way of investigating 
 the subject is to examine each stratum as it appears on dissection, 
 and then to consider the inguinal canal as a whole. First, then, of 
 the aponeurotic stratum. 
 
 The lower border of the aponeurosis of the external 
 Btraium, and oblique, extending from the spine of the ilium to the 
 external ab- S pi ne O f the pubes, constitutes Poupart's ligament, or 
 
 dominal ring. r * , , 
 
 the crural arch. Above, and somewhat to the outer 
 side of the spine of the pubes, is situated an opening in the apon- 
 eurosis called the ' external abdominal ring,' which varies in size 
 
 Fig. 61. 
 
 1. External abdominal 
 
 ring. 
 
 2. Gimbernat's ligament. 
 
 3. Poupart's ligament, or 
 
 outer pillar of the 
 ring. 
 
 4. Internal pillar of the 
 
 ring. 
 
 5. Position of the inter- 
 
 nal ring, in dotted 
 outline. 
 
 DIAGRAM OF POUPART'S LIGAMENT, OF THE APONEUROSIS OF THE EXTERNAL OBLIQUE, 
 AND OF THE EXTERNAL ABDOMINAL RING. 
 
 and shape in different individuals. In the male it is a triangular 
 opening about an inch long, with its base towards the pubes, and 
 will admit the passage of a finger. In the female it is smaller, 
 and transmits the round ligament of the uterus. It is bounded 
 
318 PARTS CONCERNED IN INGUINAL HERNIA. 
 
 above and below by the free margins of the aponeurosis, which are 
 called its 6 columns or pillars.' The inner or upper pillar is thin, 
 and is attached to the front of the pubes, and decussates with 
 its fellow of the opposite side in front of the symphysis. The 
 outer pillar is thicker and stronger, and has three attachments ; 
 one to the spine of the pubes (Poupart's ligament), another for 
 nearly an inch along the linea ilio-pectinea (Grimbernat's liga- 
 ment), and a third (triangular ligament) consists of a few fibres 
 which pass upwards and inwards beneath the inner pillar as far as 
 the linea alba, where they are continuous with the aponeurosis 
 of the opposite side. At the lower part of the aponeurosis 
 of the external oblique, there are a number of arched fibres called 
 * intercolumnar bands? which are strongest at its lowest part, 
 above the external ring. Their purpose is to strengthen the 
 opening and prevent the ring from enlarging. 
 
 Attached to the margin of the external ring is a thin fascia, the 
 intercolumnar or spermatic fascia, which is prolonged over the 
 spermatic cord, and forms a thin covering over it extending down 
 into the scrotum. The spermatic cord in its passage through the 
 ring rests upon the external pillar. 
 
 Muscular ^ exam i ne the muscular stratum, the aponeurosis 
 
 stratum and of the external oblique must be reflected. This is to 
 cremaster. j^ done by making a transverse incision through it, 
 from the spine of the ilium to the linea alba and another at right 
 angles to it, along the linea alba to the pubes. The triangular 
 flap of aponeurosis is to be reflected and turned downwards, 
 without injuring the external ring or the crural arch. The 
 muscular stratum is now fairly exposed. This stratum consists 
 of the combined fibres of the internal oblique and transverse 
 muscles : these, so far as our present subject is concerned, may be 
 considered as one, having the same origin, direction, and insertion. 
 Their origin is from the outer half of the crural arch ; their direc- 
 tion is transversely towards the mesial line, and they terminate 
 upon a thin aponeurosis termed the ( conjoined tendon,' which is 
 inserted into the upper part of the pubes and the linea alba 
 (fig. 62). This tendon is situated immediately behind the ex- 
 
PARTS CONCERNED IN INGUINAL HERNIA. 
 
 319 
 
 ternaLring, for the purpose of strengthening the abdominal wall 
 just at a part where, without such provision, the liability to 
 hernia would have been very great. 
 
 From the middle of the crural arch, and from the lower part of 
 the internal oblique, arises the * cremaster muscle,' which is thin 
 and pale, or the reverse, according to the condition of the 
 subject. Its fibres descend in front of the cord, and then arch up 
 again towards the pubes, forming a series of loops of different 
 
 Fig. 62. 
 
 1. Conjoined tendon of 
 internal oblique and 
 transversalia. 
 
 2. Cremaster muscle 
 passing down in 
 loops over the 
 cord. 
 
 DIAGRAM OF THE LOWER FIBRES OF THE INTERNAL OBLIQUE AND TRANSVERSALIS, WITH 
 THE CREMASTER MUSCLE. 
 
 lengths ; some, reaching only as low as the external ring, others 
 lower still, whilst the lowest cover the tunica vaginalis of the 
 testicle. Its nerve comes from the genital branch of the genito- 
 crural, and its artery from the deep epigastric. The internal 
 oblique and transversalis must now be reflected, by making inci- 
 sions similar to those for the reflection of the aponeurosis of the 
 external oblique : this must be done carefully, so as to disturb as 
 
320 
 
 PARTS CONCERNED IN INGUINAL HERNIA. 
 
 Fascial 
 stratum. 
 
 little as possible the transversalis fascia, which lies immediately 
 behind. 
 
 The third and last stratum is the fascia, which lies 
 behind the transversalis muscle. It is attached, below, 
 to the crural arch, thence ascends, and gradually 
 diminishing in thickness, is lost on the under surface of the 
 transversalis muscle. Its inner border is connected to the margin 
 of the rectus, to the lower margin of the conjoined tendon, and 
 
 Fig. 63. 
 
 1. Internal abdominal 
 
 ring. 
 
 2. Position of the ex- 
 
 ternal abdominal 
 ring, in dotted 
 outline. 
 
 3. Epigastric a. in dot- 
 
 ted outline. 
 
 4, 4. Sheath of the femo- 
 ral vessels, con- 
 tinued from the 
 fascia transver- 
 salis. 
 
 5. Femoral a. 
 
 6. Profundaa. 
 
 7. Saphena v. 
 
 8, 8. Fascia t ransver- 
 salis. 
 
 DIAGRAM OF THE FASCIA TRANSVERSALIS SEEN FROM THE FRONT. 
 
 also to the pubes. This fascia is strongest just behind the external 
 ring, and but for it and the conjoined tendon, there would be a 
 direct opening into the cavity of the abdomen through the external 
 ring. The outer half of the fascia is very firmly connected to the 
 crural arch, and also to the fascia iliaca ; but the inner half is 
 loosely connected with the crural arch, and passes down under it, 
 over the femoral vessels into the thigh, and forms what is called 
 6 the sheath of the femoral vessels.' 
 
PARTS CONCERNED IN INGUINAL HERNIA. 321 
 
 The opening in the fascia transversalis through which 
 abdominal the spermatic cord passes, is called the ' internal abdo- 
 nng. minal ring.'* It corresponds to a point midway between 
 
 the anterior superior spine of the ilium and the symphysis pubis, 
 and about two-thirds of an inch above the crural arch. It is oval 
 in shape, with the long diameter directed nearly vertically ; its 
 margin is well defined on the pubic side, but not on the iliac, and 
 from its border is continued forwards a funnel-shaped prolongation 
 over the cord as it passes through the opening. This covering, 
 thin and delicate, is termed the ' infundibuliform fascia.' (This 
 is not seen in the diagram.) Close by the inner border of the in- 
 ternal ring, the epigastric artery will be found ascending to enter 
 the substance of the rectus. 
 
 To see that part of the peritoneum concerned in inguinal hernia, 
 the fascia transversalis must be removed by incisions similar to 
 those recommended before. The fascia is easily separable from 
 the peritoneum, which is situated immediately behind it. The 
 peritoneum at the inner ring presents a well-marked depression, 
 which varies, however, considerably ; in some being scarcely visible ; 
 in others, being continued downwards into the inguinal canal, in 
 the form of a pouch. In some instances, a communication will be 
 found still existing between the general cavity of the peritoneum 
 and the tunica vaginalis testis. 
 
 Having examined the several strata through which 
 ^* e s P erma ^ c cor( l passes, replace them in their 
 natural position, and examine the inguinal canal as a 
 whole. You will perceive that its direction is obliquely downwards 
 and inwards. Its length in a well-formed adult male is from one 
 and a half to two inches. It is bounded in front by the aponeurosis 
 of the external oblique ; behind, by the fascia transversalis and the 
 conjoined tendon of the internal oblique and transversalis; above, 
 by the lower fleshy fibres of the internal oblique and transversalis ; 
 below bv the crural arch 
 
 * Or the inner aperture of the inguinal canal. 
 Y 
 
322 PAKTS CONCEKNED IN INGUINAL HEKNIA. 
 
 In a surgical point of view this is one of the most 
 
 Course and . . . 
 
 relations of important arteries in the body. It arises from the ex- 
 the epigas- ternal iliac, just before this vessel passes under the 
 
 trie artery. ' J r 
 
 crural arch. It ascends inwards between the fascia 
 transversalis and the peritoneum, forms a gentle curve round the 
 inner side of the internal abdominal ring, and consequently on 
 the inner side of the spermatic cord, and then enters the rectus 
 muscle, in which it is gradually lost. 
 
 The artery is accompanied by two veins, of which the larger is 
 constantly found on the inner side of it. They terminate by a 
 single trunk in the iliac vein. 
 
 Branches ^ *^ e Branches ^ * ne epigastric artery the most 
 
 of the epi- important is the 'pubic.' It runs inwards, behind the 
 gastric. crural arch, towards the pubes, and derives its chief 
 practical interest from the fact that it is liable to be wounded in 
 dividing the stricture in femoral hernia.* But its size varies in 
 different subjects, and is sometimes so small as to escape observa- 
 tion. The second branch is the ' cremasteric.' It supplies the 
 coverings of the cord, and chiefly the cremaster muscle. After 
 giving off other unnamed muscular branches, the main trunk ter- 
 minates in the rectus by minute inosculations with the internal 
 mammary. 
 
 Such is an outline of the anatomy of the parts concerned in 
 inguinal hernia. The description applies equally to the female, 
 provided the round ligament be substituted for the spermatic 
 cord. Of course the inguinal canal is proportionably smaller, and 
 there is no cremaster. 
 
 When a piece of intestine escapes through the inner 
 Nomenclature L , , , . . . , . , . 
 
 of the several ring, along the inguinal canal with the cord, and pro- 
 kinds of in- trudes through the outer ring, it is called an external^ 
 
 gumal hernia. . . . . T _ . . ' 
 
 or oblique inguinal nerma. it tne intestine stop in the 
 
 * There is a preparation (No. 83, Ser. 17) in the Museum of St. Bartholomew's Hos- 
 pital quite to the point. The patient had profuse haemorrhage, which commenced 
 five hours after the operation. He died with peritonitis. 
 
 t A hernia is sometimes called external or internal, according to the relationship 
 of the protrusion to the epigastric artery ; thus, an oblique inguinal hernia which first 
 protrudes through the inner ring is called an external hernia, and vice versa. 
 
PARTS CONCERNED IN INGUINAL HERNIA. 323 
 
 inguinal canal, it is called an incomplete inguinal hernia; such 
 an one is generally of small size, and sometimes difficult of detec- 
 tion. Lastly, if a portion of intestine escape at once through the 
 external ring, then it is called an internal or direct inguinal 
 hernia. 
 ~ . , An oblique inguinal hernia has all the coverings of 
 
 Coverings 01 * ' 
 
 the different the cord. Beneath the skin, therefore, and the sub- 
 hermse. cutaneous tissue there will be 
 
 1. The spermatic fascia, derived from the aponeurosis of the 
 external oblique. 
 
 2. The cremaster muscle, derived from the internal oblique 
 and transversalis. 
 
 3. The infundibuliform fascia, derived from the fascia trans- 
 versalis. 
 
 The incomplete inguinal hernia will be covered by 
 
 1. The aponeurosis of the external oblique. 
 
 2. The cremaster. 
 
 3. The infundibuliform fascia. 
 
 The direct inguinal hernia will be covered by 
 
 1. The spermatic fascia. 
 
 2. The fascia transversalis.* 
 
 In all cases, or at any rate with very few exceptions, the im- 
 mediate investment of the intestine is the peritoneum. This con- 
 stitutes the sac of the hernia. The opening of the sac, communi- 
 cating with the abdomen, is called its mouth, then comes the 
 neck, and, lastly, the body or expanded part of the sac. 
 Con enltal There are two varieties of oblique inguinal hernia, 
 and infantile termed the ' congenital ' and the ' infantile,' to which a 
 hernia. passing allusion must be made. The congenital^ 
 
 * What becomes, it may be asked, of the fibres of the conjoined tendon of the in- 
 ternal oblique and transversalis ? They are either protruded before the peritoneum, or 
 permit the hernia to slip between them. 
 
 f The term ' congenital ' applied to this form of hernia is apt to suggest the idea 
 that it occurs at birth. But this is not of necessity so. Although the state of parts 
 favourable to its occurrence exists at birth, the hernia itself may not take place till 
 many years afterwards ; in fact, at any period of life, 
 
 Y2 
 
324 PARTS CONCERNED IN INGUINAL HERNIA. 
 
 variety occurs when a protrusion of intestine takes place through 
 the narrow canal, which in some cases persists between the general 
 cavity of the peritoneum and the tunica vaginalis testis, in conse- 
 quence of the non-obliteration of the original communication 
 between them. In this variety, the intestine surrounds the tes- 
 ticle, and the hernial sac is formed by the tunica vaginalis testis 
 (fig. 64). The infantile variety is rare, and occurs when the 
 original peritoneal canal alluded to, is only partially obliterated. 
 The result of which is, that the tunica vaginalis testis may reach 
 as high as the external or even the internal abdominal ring. Now 
 in this variety of hernia, the Intestine protrudes a sac behind the 
 abnormal extension of the tunica Fig. 64. * 
 
 vaginalis ; so that, in front of 
 the hernia there are three layers 
 of peritoneum ; namely, two 
 formed by the tunica vaginalis 
 testis, and one by the hernial 
 sac (fig. 64). 
 Position of The spermatic cord is generally situated behind and 
 
 spermatic on the outer side of a hernial sac. In some cases, how- 
 cord in refer- ,, . ., ... r- 11 j 
 
 ence to the ever, the hernia separates the constituents ot tne cord, 
 hernia. 8O that one or other of these may lie on the front of 
 
 the protrusion. 
 
 The stricture may be seated either at the external 
 
 stricture %> tlie interna ^ rin g> or at anv intermediate part. 
 Sometimes there is a double stricture, one at the ex- 
 ternal ring, the other at the internal. 
 
 The stricture, however, may be caused by the mouth of the sac 
 itself, independently of the parts outside it ; for the peritoneum 
 may become thickened and indurated, and sufficiently unyielding 
 to strangulate the protruded parts. 
 
 Direction in We cannot do better than adhere to the golden rule 
 which the laid down by Sir A. Cooper ; namely, to divide the 
 shoSdbe stricture, in all cases, directly upwards. In this direc- 
 divided. tion, we are least likely to wound the epigastric artery. 
 
 * Fig. 64. The arrows denote the course of the hernia. 
 
POSITION OF ABDOMINAL VISCERA. 325 
 
 Whoever has the opportunity of dissecting an old 
 
 Changes pro- 
 duced by an hernia, of some size, will observe that the obliquity 
 
 lar s e of the inguinal canal is destroyed. The constant 
 dragging of the protruded viscera gradually brings the 
 internal ring nearer to the external, so that at last the one gets 
 quite behind the other, and there is a direct opening into the 
 abdomen. But the position of the epigastric artery with regard 
 to the sac remains unaltered. It is still on the inner side of the 
 neck of the sac. 
 
 In hernia of long standing, all its coverings undergo a change. 
 They become thickened and hypertrophied to such an extent, and 
 so altered from what they once were, that they scarcely look like 
 the same parts. 
 
 Expose the contents of the abdomen, by an incision from the 
 ensiform cartilage to the pubes a little to the left side of the 
 linea alba, so as to preserve a ligament, ' ligamentum teres,' 
 which passes from the umbilicus to the liver, and also a cord, 'the 
 urachus,' which ascends in the middle line from the bladder to the 
 umbilicus ; then make another incision transversely on a level 
 with the umbilicus, and turn the flaps outwards. 
 
 On the under surface of the lower right flap, the 
 peritoneum is raised into a fold by a fibrous cord, 
 passing from the bladder to the umbilicus ; this is the * urachus^ 
 which in foetal life is a tube connecting the bladder with the 
 allantois. On either side of the urachus are two other folds in- 
 closing cords which ascend obliquely towards the umbilicus : these 
 are the impervious remains of the umbilical arteries. 
 
 Take now a survey of the viscera before they are disturbed from 
 their relative positions. 
 
 . In the right hypochondrium the liver is seen project- 
 
 on opening ing more or less below the cartilages of the ribs, and 
 the abdomen. the fundus o f tne gall-bladder below the edge of the 
 liver, near the end of the ninth costal cartilage. In the left hypo- 
 chondrium is seen more or less of the stomach. Across the 
 umbilical region extends a broad fold of the peritoneum containing 
 fat, the great omentum, which descends from the lower border of 
 
326 POSITION OF ABDOMINAL VISCERA. 
 
 the stomach to the pelvis, forming a curtain over the convolutions 
 of the small intestines. The breadth of this fold varies in different 
 instances, sometimes being so shrunk and crumpled as to be scarcely 
 visible. The lower part of the belly and part of the pelvis are 
 occupied by the small intestines. The urinary bladder is not 
 apparent, unless distended sufficiently to rise out of the pelvis. 
 In the right iliac fossa is the ' caput coli,' the commencement of 
 the large intestine ; but the ascending part of the large intestine 
 in the right lumbar region, and the descending part of it in the 
 left, are not visible unless distended : they lie contracted at the 
 back of the abdomen. These are the viscera usually seen on 
 opening the abdomen ; but a certain latitude is to be allowed, as 
 sometimes more of one organ is seen and less of another, according 
 as this or that is distended or hypertrophied. Much also depends 
 upon the amount of pressure which the ribs have undergone during 
 life. 
 
 Particular ^ e position of each viscus should now be examined 
 
 position of separately, and first that of the stomach. 
 
 The stomach is irregularly conical in shape. Its 
 ' great end is situated in the left hypochondrium ; its 
 narrow or pyloric end extends obliquely across the epigastrium into 
 the right hypochondrium, where it is overlapped by the liver. 
 The relative position and size of the stomach vary according to the 
 amount of distention ; when much distended the anterior surface, 
 owing to the greater mobility of the great curve and the pyloric 
 end of the stomach, is turned upwards, and the lower border, 
 forwards. 
 
 The first part of the intestinal canal is termed ' intes- 
 tinum duodenum,' because it is about twelve inches 
 long. Commencing at the pyloric end of the stomach (p. 338), the 
 duodenum ascends as high as the neck of the gall-bladder ; then, 
 suddenly bending, it descends in front of the right kidney ; lastly, 
 making another bend, it crosses the spine obliquely towards the 
 left side of the second lumbar vertebra : here the intestinum 
 * jejunum' begins, and this part of the canal may be seen by 
 raising the transverse colon. Thus then, the * duodenum ' describes 
 
POSITION OF ABDOMINAL VISCERA. 327 
 
 a kind of horse-shoe curve, of which the concavity is towards the 
 left, and embraces the large end or head of the pancreas. For 
 convenience of description, the duodenum is divided into an ascen- 
 ding, a descending, and a transverse portion. The first is completely 
 surrounded by a peritoneal covering ; the second and third are 
 only covered by peritoneum in front, and are fixed to the back of 
 the abdomen. The relative anatomy of the duodenum will be 
 more fully seen hereafter. 
 
 Pursuing its course from the left side of the second 
 
 T * A 
 
 ileum!" 1 lumbar vertebra, the intestinal canal forms a number 
 of convolutions, which are loosely connected to the 
 spine by a broad peritoneal fold termed the ( mesentery? Of these 
 convolutions, the upper two-fifths constitute the 6 intestinum 
 jejunum ; ' the lower three-fifths the ( intestinum ileum? This 
 is an arbitrary division. There is no definite limit : the character 
 of the bowel gradually changes that is, it becomes less vascular, 
 has fewer folds of the lining membrane, and its coats are therefore 
 less substantial to the feel. 
 
 Commence- ^ n * ne r ^ n ^ ^ ac f ssa > the small intestine opens into 
 ment of large the left side of the colon, which is easily recognised by 
 intestine. ^ g saccu i a t e( i appearance: here the large intestine 
 begins: here is the ilio-ca3cal valve (fig. 65). Immediately below 
 the junction, the large intestine is expanded into a blind pouch, 
 called the caecum or caput coll. Into the back part of this pouch 
 opens a little tube closed at the other end, called the ' appendix 
 vermiformis.' This tube is generally three inches long, about as 
 thick as a tobacco-pipe, and is either coiled up behind the caecum, 
 or connected to it by a peritoneal fold, so as to hang loose in the 
 pelvis. The commencement of the large intestine is generally 
 confined by the peritoneum to the iliac fossa, in which it lies.* 
 Tracing it from this point, it ascends through the right lumbar 
 region in front of the right kidney ; then, crossing the umbilical 
 
 c * But this is not invariably so. The bowel is, in some subjects, connected to the 
 fossa by a fold of peritoneum or a ' meso-c&cum.' I have often seen this fold suf- 
 ficiently loose to allow the caput coli to travel over to the left iliac fossa. 
 
328 POSITION OF ABDOMINAL VISCERA. 
 
 region towards the left side,* it descends in front of the left 
 kidney f down the left lumbar region into the iliac fossa, where it 
 curves like the letter S. These successive portions of the large 
 intestine are termed, respectively, the ascending, transverse, de- 
 scending, and sigmoid parts of its course. Lastly, the bowel enters 
 the pelvis on the left side of the sacrum, and here takes the name 
 of ' rectum.'' This term, so far as concerns the human subject, is 
 
 Fig. 65. 
 
 1. Ileum. 
 
 2. Csecum or caput coli. 
 
 3. Appendix vermiformis. 
 
 SECTION THROUGH THE JUNCTION OF THE LARGE AND SMALL INTESTINE TO SHOW THE 
 
 ILIO-C^CAL VALVE. 
 
 misapplied ; the canal runs anything but a straight course through 
 the pelvis, for it curves so as to adapt itself to the sacrum. 
 
 Looking at the entire course of the colon, observe that it forms 
 
 * This transverse part of the colon, in some instances, makes a coil behind the 
 stomach to the diaphragm ; such a state of things, when the bowel happens to be dis- 
 tended, is apt to give rise to symptoms of diseased heart. See some observations in 
 point by Dr. Copland, in Lond. Med. Gaz. 1847, vol. v. p. 660. 
 
 f The contiguity of the ascending and descending colon to the right and left kidney 
 respectively, explains the occasional bursting of renal abscesses into the intestinal 
 canal. 
 
POSITION OF ABDOMINAL VISCERA. 329 
 
 an arch, of which the concavity embraces the convolutions of the 
 small intestines. 
 
 The small intestines, including the duodenum, vary 
 
 Length of the " J 
 
 alimentary from sixteen to twenty-four feet in length, and the 
 canal. large intestines from five feet to five feet and a half ; 
 
 these measurements are subject to some variation according to the 
 height of the individual. In round numbers, we may say that the 
 small and large intestines are from five to six times the length of 
 the body. 
 
 The liver occupies the whole of the right hypo- 
 
 The liver. . , . , ,, . . . & . -^ 
 
 chondrium, and extends over the epigastric region mor 
 or less into the left. Unless the individual be very corpulent, we 
 can ascertain during life the extent to which the liver projects 
 below the costal cartilages, and the general dimensions of the 
 organ may be tolerably well told by percussion. Its anterior 
 border is sharp and thin; its posterior is broad and connected 
 to the diaphragm by peritoneal ligaments. Its under surface 
 overlays part of the stomach, of the duodenum, of the right 
 kidney, of the transverse colon, and of the suprarenal capsule : its 
 upper surface is convex, and accurately adapted to the arch of the 
 diaphragm. To this muscle the liver is connected by folds of 
 peritoneum, called ' ligaments.' One of these, nearly longitudinal 
 in direction, and called the ' suspensory,' or, from its shape, the 
 6 falciform ' ligament, is situated a little to the right of the mesial 
 line. The free edge of it in front contains the impervious remains 
 of the umbilical vein, called the ' round ' ligament. The sus- 
 pensory ligament, traced backwards, leads to another broad fold 
 extending horizontally from the diaphragm to the posterior 
 border of the liver ; this constitutes the ' lateral ' ligament, right 
 or left, according as we trace it on one or other side of the falciform 
 ligament. 
 
 The junction of the lateral and falciform ligaments is described 
 by some authors as the coronary ligament. 
 
 The gall-bladder is the reservoir for the bile, and is 
 
 closely confined by the peritoneum in a slight depres- 
 sion on the under surface of the liver. Its lower end or fundus 
 
330 POSITION OP ABDOMINAL VISCERA. 
 
 projects beneath the cartilage of the ninth rib. This is important 
 practically. It sometimes happens that the gall-bladder, in conse- 
 quence of some obstruction to its duct, becomes unusually distended, 
 and occasions a swelling below the margin of the ribs, which might 
 be mistaken for an hepatic abscess.* The close proximity of the 
 gall-bladder to the duodenum and the transverse colon explains the 
 occasional evacuation of gall-stones by ulceration into the in- 
 testinal canal, f 
 
 The spleen is deeply situated in the left hypo- 
 chondrium, between the stomach and the ninth, tenth, 
 and eleventh ribs. Its outer surface is smooth and convex, to 
 correspond with the diaphragm and the ribs; its inner surface, 
 where its great vessels enter, is concave and connected to the 
 great end of the stomach by a peritoneal fold called the f gastro- 
 splenic omentum? Generally, too, the spleen is connected by a 
 small peritoneal fold, the suspensory ligament, to the under 
 aspect of the diaphragm.^ 
 
 This is the salivary gland of the abdomen. It lies 
 behind the stomach, transversely across the spine, about 
 the level of the first lumbar vertebra. Its right end or head is con- 
 tained within the curve of the duodenum : its left end or tail 
 extends as far as the spleen. The further connections and relations 
 of the pancreas cannot in this stage of the dissection be satis- 
 factorily seen. 
 
 The kidneys are situated in the lumbar region, 
 nearly opposite the two lower dorsal and the two upper 
 lumbar vertebrae ; the right being a little lower than the left. 
 They lie imbedded in fat, partly upon the quadratus lumborum, 
 partly upon the psoas. In contact with the right kidney, we have 
 the liver, the second part of the duodenum, and the ascending 
 colon; in contact with the left, are the spleen, the end of the 
 pancreas, and the descending colon. 
 
 * See cases in point recorded by Andral, Clin. Med. torn. iv. ; and Graves, Dublin 
 Hospital Eeport, vol. iv. 
 
 f See preparations in the Museum, Ser. 16, No. 84. 
 
 J Every now and then we find in the gastro-splenic omentum one or more little 
 spleens in addition to the large one. 
 
PEKITONEUM. 331 
 
 This body is situated at the top of the kidney. It 
 Renal capsule. . ., ,. , ^ r 
 
 lies upon the crus ol the diaphragm. You will see 
 
 the right renal capsule by lifting up the liver ; the left, by lifting 
 up the spleen, and the great end of the stomach. 
 
 A certain range of motion being necessary to the 
 
 Peritoneum, , . . . . J 
 
 abdominal viscera, they are provided with a serous 
 membrane, called the ' peritoneum.' This membrane is, like other 
 serous membranes, a closed sac, one part of which lines the con- 
 taining cavity, the other is reflected over the contained viscera. 
 These are respectively termed the parietal and the visceral layers. 
 In the female, however, it is not, strictly speaking, a closed sac, 
 since it communicates with the cavity of the uterus through the 
 Fallopian tubes. The internal surface of the peritoneum is smooth 
 and polished, and lined by squamous epithelium : the external 
 surface, the subperitoneal tissue, is composed of areolar tissue 
 which connects the internal layer to the invested viscus or 
 abdominal parietes. There is nothing between the parietal and 
 the visceral layers, in other words, inside the sac, but just sufficient 
 moisture to lubricate its smooth and polished surface. The viscera 
 are all, more or less, outside the sac ; some lie altogether behind 
 it, as the pancreas, kidneys, and renal capsules ; others, as the lower 
 parts of the duodenum, caecum, ascending and descending colon, 
 are only partially covered by it ; while others, as the stomach, 
 liver, jejunum, ileum, and some parts of the large intestine, are 
 completely invested by it : these latter push the visceral layer 
 before them, and so give rise to membranous folds ; the larger the 
 fold, the freer is the mobility of the viscus which occasions it. 
 
 Now trace the peritoneum as a continuous membrane. 
 ^^ nce *he peritoneum is a perfect sac, it matters not 
 where we begin, for we must come back to the starting 
 point. 
 
 Supposing, then, a longitudinal section to be made through the 
 viscera in the middle of the body, one might trace the peritoneum 
 thus beginning at the diaphragm, and taking, for brevity's sake, 
 two layers at a time (fig. 66). 
 
 From the diaphragm two layers of peritoneum proceed to the 
 
332 
 
 PEKITONEUM. 
 
 Fig. 65 a. 
 
 liver, forming its lateral ligaments ; they separate to inclose the 
 liver, meet again on its under aspect, and pass on, under the name 
 of the gastro-hepatic omentum, to the small curve of the stomach. 
 Separating here they embrace the stomach, and meeting again at 
 
 its greater curve, pass down as a 
 curtain over the small intestines 
 to form the great omentum. At 
 the lower margin of the great 
 omentum, they are reflected up- 
 wards (so that the great omentum 
 consists of four layers), to the front 
 of the colon, which they inclose, 
 and after joining again at the back 
 of the colon, proceed to the spine, 
 forming the trans verse meso-colon. 
 At this situation the two layers di- 
 verge, the upper one ascends in 
 front of the pancreas, and the 
 crura of the diaphragm to its 
 under surface, at which point we 
 started.* 
 
 The lower layer is reflected from 
 the spine over the small intestines 
 back again to the spine, to form 
 the mesentery. From the root of 
 the mesentery it descends into 
 the pelvis, and invests the upper 
 two-thirds of the rectum. From 
 the rectum, in the male, it is re- 
 flected to the posterior part of the 
 bladder, forming the recto-vesical 
 
 * In foetal life, the ascending layers of the great omentum may be traced back to the 
 spine near the pancreas ; and here the layers diverge from each other. The upper 
 layer ascends in front of the pancreas to the diaphragm ; the lower layer proceeds over 
 the arch of the colon, and then back to the spine, thus forming the transverse meso- 
 colon. Its reflections afterwards are the same as in the adult. As the foetus grows, 
 the great omentum becomes adherent to the arch of the colon. 
 
 DIAGRAM OP THE PERITONEUM. 
 
PERITONEUM. 333 
 
 pouch, and thence to the wall of the abdomen, along which we 
 trace it up to the diaphragm. In the female, it is reflected from 
 the rectum on to about one inch of the posterior wall of the 
 vagina, constituting the recto-vaginal pouch, and thence over all 
 the back, but only about half-way down the front of the uterus, 
 to the posterior wall of the bladder ; after which its reflections 
 are the same as in the male. 
 
 Such is the course of the peritoneum as seen in a longitudinal 
 section, but there are certain lateral reflections which cannot be 
 seen except in a transverse section : thus, from the great .end of 
 the stomach, two layers proceed to the spleen, forming the gastro- 
 splenic omentum ; from the transverse meso-colon it is reflected on 
 either side over the ascending and descending colon. 
 
 The following parts of the alimentary canal are only partially 
 covered by peritoneum : the descending and transverse portions 
 of the duodenum, the caecum, the ascending and descending colon, 
 (with exceptional cases) the lower part of the rectum. 
 
 Anatomists speak of the lesser cavity of the peritoneum as dis- 
 tinguished from the greater. This lesser cavity, or sac of the 
 omentum, is situated behind the stomach and the descending layers 
 of the great omentum. If air be blown through the foramen of 
 Winslow (which is the constricted communication between the 
 greater and lesser cavities of the peritoneum), we distend the lesser 
 cavity; it is bounded, in front, by the lesser omentum, the stomach, 
 and the descending layers of the great omentum ; behind, by the 
 ascending layers of the great omentum, the colon, and the trans- 
 verse meso-colon ; above, by the liver. 
 
 This foramen is the narrow circular opening between 
 Winstow f *ke reater an( i lesser cavities of the peritoneum, 
 through which the two cavities communicate. It is 
 situated behind the right edge of the gastro-hepatic, or lesser 
 omentum. By passing your finger into it, you will find the 
 foramen bounded above by the lobulus Spigelii of the liver, below, 
 by the commencement of the duodenum, in front by the lesser 
 omentum, and behind by the vena cava inferior. 
 
 The several folds, formed by the reflections of the peritoneum, 
 
334 PERITONEUM. 
 
 which connect the viscera either to each other or to the back of 
 the abdomen, have now to be examined. 
 
 This is the fold which suspends the small intestines 
 ery ' from the back of the abdomen. To see it, raise the 
 great omentum and the transverse arch of the colon. Its attached 
 part or root extends from the left side of the second lumbar 
 vertebra obliquely across the spine to the right iliac fossa. The 
 loose part of the mesentery curves as it were like a ruffle, and 
 incloses the small intestines from the beginning of the jejunum to 
 the end of the ileum. Between its layers the mesenteric vessels, 
 nerves, glands, and lymphatics must be made out. 
 
 This broad fold connects the transverse colon to the 
 
 meso-IoTo & n back of the abdomen - Jt forms a sort of partition 
 dividing the abdomen into an upper compartment, 
 containing the stomach, liver, and spleen ; and a lower, containing 
 the convolutions of the small intestines. As regards the caecum, 
 the ascending and descending portions of the colon, they, as a 
 general rule, are bound down by the peritoneum in their respective 
 situations. It covers only two-thirds or thereabouts of their an- 
 terior surface ; the rest is connected by loose cellular tissue to the 
 back of the abdomen.* 
 
 This broad peritoneal fold is composed of four layers, 
 omentum anc ^ P rocee ds from the lower border of the stomach, 
 like a curtain over the convolutions of the small intes- 
 tines. Its thickness varies considerably, in thin subjects it is 
 often transparent, while in fat persons, on the other hand, it is 
 loaded with fat, and contributes in great measure to the size of the 
 abdomen. Its length also varies. In some bodies we find it extend- 
 ing far into the pelvis, in others, small and crumpled. 
 
 This fold passes from the transverse fissure on the 
 
 hepatic or under surface of the liver to the upper aspect of the 
 
 lesser omen- stomach. It is composed of two layers ; and between 
 
 them, we find the vessels and nerves going to, and the 
 
 * In some (rare) cases, the ascending and descending colon are completely sur- 
 rounded by peritoneum, and connected to the lumbar regions, respectively, by a right 
 and left lumbar meso-colon. 
 
BRANCHES OF ABDOMINAL AORTA. 
 
 335 
 
 duct coming from the liver. The right border of this reflected 
 fold is free, while the left passes on to the oesophagus. In this 
 fold the bile-duct lies to the right, the hepatic artery to the left, 
 and the vena portse behind and between them. If the finger be 
 introduced behind the right border, it' passes through the foramen 
 of Winslow into the lesser cavity of the peritoneum. 
 
 This fold proceeds from the great end of the stomach 
 iC to the 8 P leen > and is continuous below with the great 
 omentum. It contains between its layers, the ' vasa 
 
 Fig. 66. 
 
 1. Phrenic. 
 
 2. Caeliac axis. 
 
 3. Superior mesenteric. 
 
 4. Supra-renal. 
 
 5. Kenal. 
 
 6. Spermatic. 
 
 7. Inferior mesenteric. 
 
 8. Lumbar. 
 
 9. Sacra media. 
 
 BRANCHES OF THE ABDOMINAL AORTA. 
 
 brevia,' branches which proceed from the splenic artery to the 
 great end of the stomach. 
 
 Branches of m next object should be the examination of the 
 
 the abdominal arteries which supply the viscera. The aorta enters 
 
 the abdomen between the pillars of the diaphragm, 
 
 and then descending a little to the left side of the front of the 
 
336 BRANCHES OF ABDOMINAL AORTA. 
 
 spine, divides opposite the fourth lumbar vertebra into the two 
 common iliac arteries. In this course it gives off its branches in 
 the following order (fig. 66). 
 
 1. The phrenic, for the supply of the diaphragm. 
 
 2. The cceliac axis, a short thick trunk which immediately 
 subdivides into three branches for the supply of the stomach, the 
 liver, and the spleen. 
 
 3. The superior mesenteric, for the supply of all the small in- 
 testines and the upper half of the large. 
 
 4. 5. The supra-renal and the renal arteries. 
 
 6. The spermatic, for the testicles in the male, and the ovaries 
 in the female. 
 
 7. The inferior mesenteric, for the supply of the lower half of 
 the large intestine. 
 
 8. The lumbar, a series of branches, analogous to the intercostals, 
 for the supply of the back part of the abdomen. 
 
 9. The arteria sacra media, which is given off at the bifurca- 
 tion of the aorta, and runs down in front of the sacrum. 
 
 These branches are to be traced throughout in the order most 
 convenient. Take the caeliac axis first. To dissect this artery and its 
 branches, the liver must be well raised, as in fig. 67, and a layer of 
 peritoneum removed from the gastro-hepatic omentum. There is 
 a close network of very tough tissue about all the visceral branches 
 of the aorta. This tissue consists almost entirely of plexuses of 
 nerves, derived from the sympathetic system. Of these plexuses, 
 the largest surrounds the cseliac axis like a ring. This is the solar 
 plexus, or more appropriately, the brain of the abdomen, and is 
 formed by the junction of the two semi-lunar ganglia (see dissection 
 of thorax, p. 126). From this, as from a root, other secondary 
 plexuses branch off, and surround the following arteries : the 
 phrenic, coronary, hepatic, splenic, superior mesenteric, inferior 
 mesenteric, and renal : the plexus receiving the name of the arteries 
 around which they twine. It requires a very lean subject, and 
 great anatomical dexterity to trace them. 
 
BRANCHES OF ABDOMINAL AORTA. 337 
 
 PLAN OF THE BRANCHES OF THE C^LIAC AXIS. 
 
 / Coronaria vcntriculi. 
 
 ( pancreatic branches. 
 
 Splenic 
 
 j gastro-epiploica sinistra. 
 vasa breA'ia to stomach. . 
 
 ( pyloric. | pancreatico- 
 
 Hepatic ...... n gastro-epiploica dextra. i duodenalis. 
 
 (cystic. (omental. 
 
 Cseliac axis 
 
 Cseliac axis ^^ e C8e ^ ac ax i g arises from the front of the aorta, 
 and its between the pillars of the diaphragm, just above the 
 
 upper border of the pancreas. It is a very thick, 
 short trunk, which after a course of about half an inch divides 
 into three branches the coronaria ventriculi or gastric, the 
 splenic, and the hepatic. 
 
 The coronaria ventriculi, the smallest of the three, ascends a 
 little to the left towards the cesophageal end of the stomach, where 
 it gives off branches to the oasophagus, which inosculate with the 
 oesophageal offsets of the thoracic aorta. It then curves along the 
 upper border of the stomach towards the pylorus, to anastomose 
 with the pyloric branch of the hepatic artery. 
 
 The hepatic artery ascends to the right between the layers of the 
 lesser omentum to the transverse fissure of the liver, where it divides 
 into two branches, right and left, for the supply of the respective 
 lobes of the liver. 
 
 In its course to the liver, it lies to the left of the bile duct, and 
 in front of the portal vein ; all three are contained in the right 
 border of the lesser omentum. The hepatic gives off 
 
 a. The pyloric, which runs along the upper curve of the stomach 
 from right to left, and inosculates with the coronaria ventriculi. 
 
 6. The gastro-epiploica dextra, which runs behind the duo- 
 denum, then along the great curve of the stomach, from right to 
 left, and inosculates directly with the gastro-epiploica sinistra, a 
 branch of the splenic. It gives off: 1. The pancreatico duodenalis, 
 which runs down between the head of the pancreas and the de- 
 scending part of the duodenum. It supplies branches to each, and 
 
338 
 
 BRANCHES OF ABDOMINAL AORTA. 
 
 inosculates frequently with a similarly named branch of the su- 
 perior mesenteric artery. 2. Branches which descend to supply 
 the great omentum. 
 
 Fig. 67. 
 
 Gall- 
 bladder 
 
 I Spleen. 
 
 Termination 
 of bile-duct 
 
 Commencement of the jejunum. 
 
 DIAGRAM OF THE BRANCHES OF THE CJELIAC AXIS. 
 
 (Pancreas in dotted outline behind the stomach.) 
 
 1. Coronaria ventriculi. 
 
 2. Splenic a. 
 
 3. Hepatic a. 
 
 4. Pylorica. 
 
 5. Grastro-epiploica dextra. 
 
 6. Grastro-epiploica sinistra. 
 
 7. Vasabrevia. 
 
 8. Superior mesenteric a. 
 
 c. The cystic, commonly a branch of the right hepatic, ramifies 
 on the under surface of the gall-bladder, supplying its coats. 
 
 The splenic, the largest of the three, proceeds tortuously towards 
 the left side, along the upper border of the pancreas to the spleen, 
 which it enters by numerous branches. 
 
VENA 
 
 339 
 
 It gives off: 1. Several small branches to the pancreas, pan- 
 creaticce parvce. One, rather larger than the rest, which ac- 
 companies the pancreatic duct, is called pancreatica magna. 
 2. The gastro-epiploica sinistra, which runs to the right along 
 the great curve of the 
 
 Fig. 68. 
 
 curve 
 
 stomach, and inosculates 
 with the gastro-epiploica 
 dextra. 3. Vasa brevia, 
 which proceed between the 
 layers of the g astro-splenic 
 omentum, to the great end 
 of the stomach, where they 
 communicate with branches 
 from the coronaria ven- 
 triculi. 
 
 Thus the stomach is sup- 
 plied with blood by four 
 channels, which by their 
 inosculations form a main 
 artery along its lesser curve, 
 another along its greater; 
 from these, numerous bran- 
 ches are furnished to both 
 sides of the stomach. The 
 artery of the greater curve 
 also sends down numerous 
 branches to the omentum, 
 which form a beautiful net- 
 work between its layers. The 
 advantage of this free in- 
 osculation of arteries about the stomach must be apparent. 
 
 DIAGRAM OF THE VENA POBT.E. 
 
 (The arrow is introduced behind the free 
 border of the lesser omentum.) 
 
 Vena portse: 
 
 The veins which return the blood from the abdomi- 
 
 its pecu- 
 liarities. 
 
 nal portion of the alimentary canal, the pancreas, and 
 the spleen, have this peculiarity, that they do not empty 
 themselves into the vena cava, but all unite into one great vein, 
 called the i vena portse,' which ramifies throughout the liver, and 
 
 z 2 
 
340 BRANCHES OP ABDOMINAL AORTA. 
 
 secretes the bile. The trunk of the vena portse itself is from three 
 to four inches long. By tracing it downwards you find that it 
 is formed behind the great end of the pancreas, by the confluence 
 of the splenic and superior mesenteric veins (fig. 68). In its pas- 
 sage to the liver, the vena portse is accompanied by the hepatic 
 artery and the common bile-duct, lying behind and between them. 
 Traced upwards you find that at the transverse fissure of the liver 
 it divides into two branches corresponding to the two great lobes 
 of the organ. The vein ramifies in the substance of the liver like 
 an artery, and is inclosed with branches of the hepatic artery 
 and duct in a sheath called c Glisson's capsule.' The vena portse 
 may, then, be compared to the stem of a tree, of which the roots 
 arise in the digestive organs, and the branches spread out in the 
 liver. After receiving the veins corresponding to the branches 
 of the hepatic artery, the vena portse returns its blood into the 
 inferior vena cava through the vense cavse hepaticse. 
 
 The veins which empty themselves into the vena portse are also 
 peculiar, in that they have no valves. Therefore, if any obstruc- 
 tion arise in the venous circulation through the liver, the roots of 
 the portal vein are apt to become congested : this is a common 
 cause of hsemorrboids, diarrhoea, hsemorrhage from the bowels, and 
 ascites. Leeches applied to the anus have been long recognised as 
 beneficial in congestion of the liver. 
 
 The hepatic duct is composed of two trunks, one from 
 
 >duct< the right lobe and the other from the left : it is soon 
 joined by the cystic or the duct from the gall-bladder. The 
 common duct, ' ductus communis choledochusj thus formed, 
 passes along the right edge of the lesser omentum, then behind 
 the first portion of the duodenum, and opens obliquely into the 
 back part of the second portion (p. 338). This common duct is 
 from three to four inches long, and, if distended, would be about 
 the size of a small writing quill. 
 
 The great omentum, with the arch of the colon, must now be 
 turned up over the chest, and the small intestines should be pushed 
 towards the left side. Then, by removing a layer of peritoneum 
 from the mesentery, we expose the mode in which the superior 
 
BRANCHES OF ABDOMINAL AORTA. 
 
 341 
 
 mesenteric artery ramifies so as to supply the small intestines. In 
 making this dissection, the mesenteric glands immediately attract 
 notice. They lie in great numbers between the layers of the 
 mesentery, and vary considerably in size. The fine tubes, called 
 lacteal vessels, which traverse the glands, are too thin and trans- 
 Fig. 69. 
 
 1. Superior mesenteric a. 
 
 2. Colica media. 
 
 3. Colica dextra. 
 
 4. Ileo-colica. 
 
 5. Inferior mesenteric a. 
 
 6. Colica sinistra. 
 
 7. Arteria sigmoidea. 
 
 8. Superior hasmorrhoidal a. 
 
 PLAN OF THE MESENTERIC ARTERIES, AND THEIR COMMUNICATION. 
 
 parent to be seen under ordinary circumstances. But in cases 
 where sudden death has taken place during digestion, they are 
 found distended with chyle, and can be traced into the glands from 
 all parts of the small intestines.* After traversing the glands, 
 they all eventually empty their contents into the receptaculum 
 chyli (p. 122). 
 
 This large artery descends beneath the pancreas, over 
 mesenteric the transverse part of the duodenum (p. 338), and then 
 artery and ruDS b e t we en the layers of the mesentery towards the 
 
 branches. . J J 
 
 right iliac fossa, where it terminates in branches for the 
 
 * The arrangement of the chyliferous vessels is extremely well displayed in the 
 beautiful plates of Mascagni. 
 
342 BRANCHES OF ABDOMINAL AORTA. 
 
 supply of the caecum. Thus its course describes a gentle curve 
 from left to right. It gives off the following branches: 1, the 
 pancrecttico duodenal branch, given off close to its origin, runs up 
 to inosculate with a similar named branch of the hepatic artery ; 
 2, branches to the small intestines from ten to sixteen in number 
 are given off from the left or convex side of the curve ; while from 
 the concave side come, 3, the ileo-colic ; 4, the right colic ; and 5, 
 the middle colic arteries for the supply of the upper half of the 
 large intestines. 
 
 The student should now trace the branches to the small intes- 
 tines,, in order to see the beautiful series of arches which they form 
 by their mutual inosculations. There are three or four tiers of 
 them, each tier composed of smaller and more numerous branches 
 than the preceding. The ultimate branches ramify in circles 
 round the intestine. This circular arrangement of the vessels in 
 the coats of the bowel is practically interesting, because it enables 
 one in almost all cases to distinguish the intestine from the hernial 
 sac. 
 
 The colic branches of the superior mesenteric are the ileo-colic, 
 which is the continuation of the main trunk, and divides into two 
 branches ; one supplies the lower part of the ileum, and the other 
 the caecum : the right colic, which proceeds towards the ascending 
 colon, and the middle colic, which ascends between the layers of the 
 ineso-eolon to the arch. They are arranged after the same plan as 
 those of the small intestines ; that is, they inosculate so as to form 
 a series of arches which successively decrease in size and finally ter- 
 minate in circles round the bowel. 
 
 The superior mesenteric vein joins the splenic behind the pan- 
 creas, and forms the vena portae (p. 339). 
 
 To trace this artery.the small intestines must be drawn 
 
 Inferior me- . .. . 
 
 senteric artery over towards the right side, and the peritoneum covering 
 and branches. ^e ar ^ er y removed. It is given off about two inches 
 above the bifurcation of the aorta. Descending into the pelvis over 
 the left common iliac artery, it passes between the layers of the 
 meso-rectum, and, taking the name of superior haemorrhoidal, is 
 finally distributed to the upper part of the rectum. Its branches 
 
BRANCHES OF ABDOMINAL AORTA. 343 
 
 are : 1, The colica sinistra, which crosses over the left kidney and 
 supplies the descending colon ; 2, the sigmoidea, which is distributed 
 to the sigmoid flexure ; and 3, the superior hcemorrhoidal, which 
 supplies the rectum, and will be dissected with the side view of the 
 pelvis. 
 
 These inosculate in the form of arches. The colica sinistra, too, 
 forms a large arterial arch with the colica media, so that there is a 
 chain of arterial communications from one end to the other of the 
 intestinal canal (fig. 69). 
 
 The inferior mesenteric vein joins the splenic behind the pancreas. 
 
 To see the relations of the duodenum and the pancreas, two 
 ligatures about an inch apart should be placed on the upper end of 
 the jejunum, and two others at a similar distance apart on the lower 
 end of the sigmoid flexure of the colon. The intestines should be 
 cut through between each set of ligatures, and the intermediate 
 portions of the small and large intestines removed. By turning up 
 the stomach we expose at once the horse-shoe course of the duo- 
 denum round the great end of the pancreas. 
 
 The duodenum (p. 338) commences at the pyloric end of 
 the stomach, and terminates on the left side of the second 
 lumbar vertebra. It is divided into three parts, an ascending, de- 
 scending, and transverse. 
 
 The first portion ascends obliquely as high as the neck of the gall- 
 bladder ; then making a sudden bend, it descends in front of the 
 right kidney as low as the third lumbar vertebra. Lastly, making 
 another bend it ascends obliquely across the spine to the left side 
 from the third to the second lumbar vertebra : here the canal takes 
 the name of jejunum. 
 
 Thus the duodenum describes a horse-shoe curve, the concavity 
 of which is towards the left side, and embraces the head of the 
 pancreas. The first part of the duodenum is completely invested 
 by peritoneum, and is comparatively loose, that the movements 
 of the stomach may not be restricted. The second and third parts 
 are only covered by peritoneum in front. Into the descending 
 portion, the common bile duct and the pancreatic duct empty 
 themselves, either by separate or conjoined openings. 
 
344 KIDNEYS AND UKETER. 
 
 This great salivary gland of the abdomen is situated 
 immediately behind the stomach (p. 338). It is of an 
 elongated form, and is placed transversely across the spine ; its 
 larger end, or head, is embraced by the duodenum ; its lesser is in 
 contact with the spleen. The splenic artery and vein run along 
 the upper border of the gland; the lower border is in relation 
 with the transverse portion of the duodenum, from which it is 
 separated by the superior mesenteric vessels. Posteriorly the 
 pancreas rests upon the inferior vena cava, the left kidney, the 
 left supra-renal capsule, and the commencement of the vena 
 portae. Its duct runs from left to right near the lower border and 
 anterior surface of the gland, and empties itself into the back part 
 of the descending portion of the duodenum, conjointly with, or 
 close to, the opening of the common bile duct. It receives 
 numerous branches from the splenic artery, which runs along its 
 upper border ; some from the superior mesenteric, which lies im- 
 mediately beneath it, and others from the gastro-epiploica dextra. 
 The liver, stomach, duodenum, pancreas, and spleen, should now 
 be collectively removed. For this purpose it is necessary to cut 
 through the ligaments of the liver, the venae cavse hepaticae, and 
 the branches of the cseliac axis. These viscera, with the re- 
 mainder of the intestinal canal, should be macerated in water, 
 while you examine all that is to be seen at the back of the abdomen ; 
 namely, the deep-seated muscles, the aorta, the inferior vena 
 cava, the kidneys, the lumbar plexus of nerves, and the sympa- 
 thetic nerve. 
 
 The kidneys are placed in the lumbar region, one on 
 each side of the spine. ' They lie imbedded in more or 
 less fat, on the quadratus lumborum, and psoas muscles, 
 nearly opposite the two lower dorsal and the two upper lumbar 
 vertebrae. On the top of each is situated a little body, called the 
 supra-renal capsule. The excretory duct of the kidney, or ureter, 
 descends almost vertically on the psoas muscle, enters the pelvis 
 over the division of the common iliac artery, and empties itself 
 into the lower part of the bladder after running obliquely through 
 its coats. 
 
DIAPHRAGM. 
 
 345 
 
 In front of the right kidney is the liver, the ascending colon, 
 and the vertical portion of the duodenum ; in front of the left, 
 the descending colon, part of the spleen, and pancreas. This ex- 
 plains how it is that a renal abscess or calculus is sometimes 
 evacuated by the rectum. 
 
 The kidneys and supra-renal capsules must be removed and 
 reserved for further examination. 
 
 Two large ganglia, the semilunar, are now to be searched for in 
 the solar plexus. They are situated on each side of the caeliac 
 axis, in the neighbourhood of the supra-renal bodies ; that on the 
 
 Fig. 70. 
 
 1 . Aorta passing be- 
 
 tween the crura. 
 
 2. Opening for oeso- 
 
 phagus. 
 
 3. Opening for vena 
 
 cava. 
 
 4. Quadratus lum- 
 
 ber urn. 
 
 5. Psoas magnns. 
 
 The dark arches 
 are the ' arcu- 
 late ligaments.' 
 
 DIAGRAM OF THE DIAPHRAGM, THE OPENINGS IN IT, AND THE PHRENIC ARTERIES. 
 
 right side will be found lying under the vena cava inferior. They 
 are more or less oval, and filaments are distributed to the supra- 
 renal and renal plexuses, and to the plexuses which surround the 
 branches of the abdominal aorta. Above it is connected with the 
 great splanchnic nerve (p. 126). 
 
 This is a partly muscular and partly tendinous arch, 
 Diaphragm, go constructed as to form a complete movable partition 
 between the chest and the abdomen; a floor for the 
 one, and a roof for the other. Its upper or thoracic surface is 
 convex ; its lower or abdominal, concave. To see the structure 
 of the arch, its peritoneal lining must be removed. We then 
 
346 DIAPHRAGM. 
 
 observe that there is a broad tendon in the centre, and that 
 muscular fibres converge to it from all sides (fig. 70). The dia- 
 phragm arises, 1. From the ensiform cartilage; 2. From the inside 
 of the cartilages of the six lower ribs by as many digitations, which 
 correspond with those of the transverse muscle of the abdomen ; 
 3. In the interval between the last rib and the spine, it arises 
 from two thin tendinous arches, called respectively, the ligamenta 
 arcuata (externum and internum). The external arch extends from 
 the last rib to the transverse process of the first lumbar vertebra, 
 and arches over the quadratus lumborum ; the internal passes from 
 the transverse process of the. first lumbar vertebra to the body of 
 the same vertebra, and arches over the psoas ; lastly, it arises from 
 the front of the bodies of the lumbar vertebra by two elongated 
 bundles, called the crura of the diaphragm. Both crura have 
 tendinous origins ; the right crus is, however, a little longer than 
 the left ; for the former arises from three or four upper lumbar 
 vertebrae and their intervening cartilages, whereas the left does 
 not descend so low by one vertebra. Between the two crura, the 
 aorta enters the abdomen. 
 
 From these various origins the fibres ascend, at first nearly 
 vertically, and then all arch inwards, and converge to be inserted 
 into the central tendon. 
 
 The central tendon is nearly the highest part of the diaphragm. 
 It presents a beautiful glistening surface, owing to the crossing of 
 its fibres; and its shape may be rudely compared to that of a 
 trefoil leaf. The chief point of interest about the tendon is, that, 
 in consequence of its connections with the pericardium, beneath 
 which it lies (p. 115), it is always maintained nearly on the same 
 level ; so that it helps to support the heart, and serves as a fixed 
 point for the insertion of the muscular fibres of the diaphragm. 
 
 There are three large openings in the diaphragm for 
 Openings the transmission of the aorta, the oasophagus, and the 
 
 inthedia- . . . , m , ,. T 
 
 phragm. inferior vena cava respectively. The aortic opening lies 
 
 between the crura in front of the spine ; it transmits, 
 
 also, the vena azygos and the thoracic duct, both of which lie rather 
 
 to the right side of the aorta. Trace the crura upwards, and ob- 
 
DIAPHRAGM. 
 
 347 
 
 Fig. 71. 
 
 serve that the inner fibres of each cross each other in front of the 
 aorta, somewhat like the letter X.* Just above the crossing, and 
 a little towards the left side of it, is the cesophageal opening ; this 
 is entirely muscular, and transmits the oesophagus and the pneumo- 
 gastric nerves. The opening for the vena cava is situated in the 
 central tendon, rather to the 
 right of the middle line: 
 observe that the vein is in- 
 timately connected to its 
 margin, so that it may be 
 kept permanently open. 
 Lastly, there pass through 
 the crus, on each side, the 
 sympathetic, the greater and 
 lesser splanchnic nerves. 
 
 The nerves of the dia- 
 phragm are the phrenic 
 (p. Ill ), and the five or six 
 lower intercostal nerves on 
 each side. Its blood vessels 
 are the two phrenic, derived 
 from the aorta, the internal 
 
 DIAPHRAGM FROM ITS UPPER SURFACE. 
 
 (The dotted lines show how much it descends 
 when it contracts.) 
 
 mammary (p. 103), and the 
 lower intercostal. 
 
 F The diaphragm is the great muscle concerned in in- 
 
 the dia- spiration. Truly it may be said with Haller, that it is 
 phragm. < musculus post cor nobilissimus.' During inspiration the 
 muscular sides of the diaphragm contract, and become less arched 
 (as shown by the dotted line in fig. 71); the floor of the chest 
 sinks in consequence, and more room is made for the expansion of 
 the lungs. During expiration the diaphragm relaxes, and the air 
 is expelled partly by the elasticity of the lungs and the thoracic 
 walls ; partly by muscular action. This alternate falling and rising 
 
 * This decussation is not invariable. But the right cms always crosses more or 
 less over the left, so that the crura are never strictly parallel. 
 
348 PSOAS MAGNUS. 
 
 of the diaphragm constitutes the mechanical part of the breathing. 
 But the diaphragm conduces to the performance of many other 
 functions. Acting in concert with the abdominal muscles, it as- 
 sists in the expulsion of the faeces and the urine, also in parturi- 
 tion and in vomiting: for in all these operations, we first take 
 in a deep breath, that the diaphragm may be in a state of con- 
 traction, and so form a resisting surface, against which the viscera 
 may be compressed by the abdominal muscles. Moreover, by its 
 rapid or spasmodic contractions it is one of the chief agents con- 
 cerned in laughing, sneezing, coughing, hiccough. 
 
 The muscles and nerves at the back of the abdomen must be 
 carefully cleaned; also, the abdominal aorta, and vena cava 
 inferior in front of the spine, without injuring the sympathetic 
 nerves, situated on each side of the bodies of the vertebrae. The 
 sheath which invests the psoas should be examined, and the 
 branches of the lumbar plexus preserved as they emerge from the 
 outer part of the muscle. 
 
 The sheath of the psoas is attached to the sides of the vertebrae, 
 the brim of the pelvis, and above to the ligamentum arcuatum 
 internum. It is this sheath which determines the ordinary course 
 of a psoas abscess, namely, beneath the crural arch into the upper 
 part of the thigh; for it is a rare exception when the matter 
 travels into the pelvis. 
 
 This long muscle arises from the bodies and trans- 
 verse processes of the last dorsal and the lumbar 
 vertebrae, and their intervening nbro-cartilages ; but 
 observe, only from the projecting borders of the vertebrae, not 
 from the central grooved part : here the fibres arise from a tendi- 
 nous arch thrown over the lumbar vessels. The muscle descends 
 vertically along the brim of the pelvis, beneath the crural arch 
 into the thigh, and is inserted by a strong tendon into the back 
 part of the lesser trochanter of the femur. 
 
 As it passes under the crural arch, the tendon of the psoas lies 
 immediately over the capsule of the hip-joint, and there is a large 
 bursa between them to facilitate the play of the tendon. It should 
 be borne in mind, that occasionally, even in young subjects, but 
 
ILIACUS INTERNUS AND ILIAC FASCIA. 340 
 
 more frequently in old ones, in consequence of wear and tear, 
 this bursa communicates with the capsule of the hip-joint. The 
 fact is interesting; for it explains how a psoas abscess some- 
 times makes its way into the hip-joint; a result almost always 
 fatal. 
 
 Once in about eight or ten subjects there is a small 
 parvus muscle called the psoas parvus. It arises from the 
 
 last dorsal and the first lumbar vertebra, and the inter- 
 vening cartilage ; thence descending in front of the great psoas, it 
 soon ends in a long flat tendon, which spreads out, and is inserted 
 into the brim of the pelvis. 
 
 Iliacus in ^^ s musc ^ e occupies the iliac fossa, and is covered 
 
 ternus and by a fascia. This iliac fascia, as it is called, is attached 
 iliac fascia. to the cregt of the ilium ^ and indirectly to the brim of 
 
 the pelvis through its connection with the sheath of the psoas. 
 But its most important attachment is to the outer half of the 
 crural arch ; here it is directly continuous with the fascia trans- 
 versalis (p. 320), so that together they present an effectual barrier 
 to the escape of intestine beneath this part of the arch.* 
 
 To return to the muscle. It arises from the iliac fossa, from 
 the ilio-lumbar ligament, f also from the capsule of the hip -joint. 
 The fibres pass beneath the crural arch, and are inserted into the 
 outer side of the tendon of the psoas. Thus the two muscles, so 
 far as their action goes, may be considered as one. 
 
 The combined action of the psoas and iliacus is to assist in 
 raising the body from the recumbent position, and to fix the 
 pelvis steadily on the thigh : this supposes the fixed point to be 
 at the trochanter minor. But supposing the fixed point to be at 
 the spine, then the muscle can raise and rotate the femur outwards. 
 
 * The iliac fossae are very liable to be the seat of suppuration, and the course which 
 the matter takes depends upon its position with regard to the iliac fascia. If the 
 matter be seated in the loose cellular tissue between the peritoneum and the fascia, it 
 usually advances just above the crest of the ilium, or else towards the groin through 
 the inguinal canal ; but, if seated beneath the fascia, the chances are that the matter 
 will make its way under the crural arch towards the upper and outer part of the thigh. 
 
 f This ligament extends from the transverse process of the last lumbar vertebra to 
 the ilium. 
 
350 QUADEATUS LUMBOKUM. 
 
 It is this action which is so troublesome to counteract in fractures 
 of the upper third of the femur. 
 
 This muscle extends from the crest of the ilium to 
 l^bornm the last rib > and is contained in a sheath formed for it 
 .and its by the aponeurotic origin of the transversalis (p. 314). 
 
 The anterior layer of its sheath is attached to the roots 
 of the transverse processes of the lumbar vertebrae, and the pos- 
 terior layer to their summits. The muscle, broader below than 
 above, arises from about an inch and a half of the crest of the 
 ilium and from the ilio-lumbar ligament : it ascends nearly per- 
 pendicularly, and is inserted into the last rib, and into the front 
 of the transverse processes of the four upper lumbar vertebras 
 by as many tendinous slips. In addition to these, a few fibres 
 frequently take origin from the transverse processes, and run 
 up to the last rib, crossing the front of the other part of the 
 muscle. The principal use of the muscle is to steady the 
 spine ; it also steadies the last rib, and enables it to serve as a 
 fixed point for the action of the intercostal muscles and the 
 diaphragm.* 
 
 By raising the quadratus, we observe the aponeurotic origin of 
 the transversalis from the summits of the transverse processes : 
 this constitutes the posterior part of its sheath, and separates the 
 muscle from the erector spinae. 
 
 Before examining the course of the aorta and its great primary 
 divisions, notice that a chain of absorbent glands extends along 
 the brim of the pelvis and the bodies of the lumbar vertebrae, 
 following nearly the course of the great blood vessels. Generally 
 speaking they are small ; only one here and there attracts obser- 
 vation. They transmit the lymphatics from the lower limbs, the 
 abdominal wall, and the testicle ; and all eventually lead to the 
 
 * The respective attachments of the quadratus lumborum, the crossing of its fibres, 
 and its mode of action, lead to the inference that it is a large intercostal muscle. It 
 is worth remembering that the outer edge of the quadratus lumborum, in a well-grown 
 adult, is about three inches from the spines of the lumbar vertebrae, and midway be- 
 tween the last rib and the crest of the ilium. It is just outside the edge of this muscle 
 that we can cut down to open the large bowel without wounding the peritoneum. 
 
PHRENIC ARTERIES. 351 
 
 receptaculum chyli, or the beginning of the thoracic duct (p. 122). 
 This is usually found on the right of the aorta, close to the second 
 lumbar vertebra. 
 -P , .. ,, The aorta enters the abdomen between the crura of 
 
 Kelations ol 
 
 the abdomi- the diaphragm about the last dorsal vertebra, and 
 nal aorta. d esce nds a little to the left side of the mesial line in 
 front of the spine, as low as the fourth lumbar vertebra, where it 
 divides into the two common iliac arteries. The exact point of 
 division cannot be specified with precision, because it varies in 
 different subjects. But for all practical purposes it is sufficient 
 to know that its division takes place about the level of the 
 highest point of the crest of the ilium. The aorta is crossed 
 in front by the splenic vein, the pancreas, the transverse por- 
 tion of the duodenum, and the left renal vein. To the right 
 side of it lie the vena cava inferior, the thoracic duct, and 
 the vena azygos. On each side are situated the sympathetic 
 nerves. 
 
 The branches of the aorta still to be examined, arise from it in 
 pairs namely, the phrenic, capsular, renal, spermatic, and lumbar. 
 See diagram (p. 335). 
 
 These arteries supply the diaphragm, and arise 
 arteries separately, or by a common trunk, from the aorta as 
 soon as it comes through the pillars (p. 345). The right 
 phrenic passes outwards, behind the vena cava, the left behind the 
 oesophagus, and both ascend to ramify extensively on the under 
 aspect of the diaphragm. Their first branches are to the supra- 
 renal capsules ; after which, each divides into two branches : an 
 internal, which supplies the anterior part of the diaphragm ; and 
 an external, distributed to the outer part of it. They inosculate 
 with each other, with the internal mammary, and the intercostal 
 arteries. The right phrenic vein terminates in the inferior 
 vena cava; the left, in the renal vein, when not in the vena 
 cava. 
 
 The capsular arteries proceed to the renal capsules. The 
 capsular veins terminate on the right side in the vena cava ; on 
 the left in the renal. 
 
352 LUMBAR ARTERIES AND BRANCHES. 
 
 The renal arteries arise from the aorta at right 
 arteries and angles, and run transversely to the kidneys. Both are 
 veins. covered by their corresponding veins. The right is 
 
 necessarily longer than the left, and passes beneath the vena cava. 
 Each, after sending a small branch to the supra-renal body, enters 
 its kidney, not as one trunk, but by several branches, correspond- 
 ing to the original lobes of the organ. The renal veios lie ,in 
 front of the arteries, and join the vena cava at right angles. 
 The left is longer than the right, and crosses over the aorta ; it 
 receives the spermatic, capsular, and sometimes the phrenic veins 
 of its own side. 
 
 The spermatic arteries arise from the front of the 
 arteries and aorta, a little below the renal. They descend along the 
 vems. psoas, behind the peritoneum, and then "through the 
 
 inguinal canal to the testicle. In the female, the corresponding 
 arteries proceed between the layers of the broad ligament to the 
 ovaries. Each artery is accompanied by two very tortuous veins, 
 which unite and then empty themselves, on the right side, into 
 the vena cava ; on the left, into the renal vein. 
 
 T , There are five of these arteries on either side : four 
 
 J-Ainibar 
 
 arteries and arise from the aorta, the fifth comes from the arteria 
 branches. sacra media. They are strictly repetitions of the inter- 
 costal arteries on a small scale, so that ' lumbar intercostals ' would 
 be an appropriate name for them. They proceed outwards over 
 the bodies of the vertebrae towards the intervertebral foramina, 
 and then, like the thoracic intercostals, divide into dorsal and 
 abdominal branches. 
 
 The dorsal branches pass between the transverse processes 
 accompanied by the posterior branches of the corresponding 
 nerves, and are of a size proportionate to the large development 
 of the muscles of the back which they supply. They also send 
 arteries into the spinal canal, some of which are distributed 
 to the cauda equina, and others to the bodies of the lumbar 
 vertebrae. 
 
 The abdominal branches all run outwards behind the quadratus 
 lumboruin, except the last, which usually runs in front. After 
 
COMMON ILIAC ARTERIES. 353 
 
 supplying the quadratus and psoas, they are lost in the wall of 
 the abdomen.* 
 
 The lumbar veins empty themselves into the vena cava in- 
 ferior. 
 
 The arteria sacra media, a diminutive continuation of the 
 aorta, proceeds from its bifurcation, and runs down in front of the 
 sacrum to the coccyx. In animals it is the artery of the tail. It 
 sends off the fifth lumbar artery, and lateral branches, which 
 anastomose with the lateral sacral arteries ; it also supplies small 
 vessels to the posterior part of the rectum. Its vein empties itself 
 either into the left common iliac vein, or into the inferior vena 
 cava. 
 
 The vena cava inferior is formed by the junction of 
 inferior! ^ ne ^ wo common iliac veins. It ascends on the right of 
 the aorta, close to the spine in the greater part of its 
 course. As it approaches the diaphragm, the vena cava passes off 
 a little to the right, to go through its tendinous opening in the 
 diaphragm, and reach the right side of the heart. Its relations, 
 beginning from below, are in front, the mesentery, the third part 
 of the duodenum, the pancreas and liver ; behind, the right renal 
 artery, the right lumbar arteries, and part of the sympathetic of 
 the right side. It receives the lumbar veins, the right spermatic 
 (the left joins the renal), the renal, the capsular,the right phrenic, 
 and the hepatic veins. 
 
 The two common iliac arteries resulting from the 
 COMMON ILIAC . . & 
 
 ARTERIES AND bifurcation of the aorta opposite the fourth lumbar 
 VEINS. vertebra, diverge from each other at an acute angle, 
 
 towards the sacro- iliac symphysis, and after a course of about two 
 inches, divide into the external and internal iliac. They lie close 
 to the vertebrae, and each, at or near its point of division, is crossed 
 by the ureter; the left is crossed by the colon, and by the inferior 
 mesentery artery. 
 
 * Just as the thoracic intercostals, by communicating with the internal mammary, 
 form a vascular ring round the chest, so do the lumbar, by communicating with 
 the epigastric, form a vascular ring, though less perfect, round the walls of the 
 abdomen. 
 
 A A 
 
354 EXTERNAL ILIAC ARTERY. 
 
 The right lies upon the right and left common iliac veins, and 
 is in relation also with the inferior vena cava. 
 
 The relations of these arteries are interesting in a practical 
 point of view ; and the most important one is their position with 
 regard to their corresponding veins. By reason of the close 
 connections of the right iliac artery with the right and left iliac 
 veins, it is easier to pass a ligature round the left artery than the 
 right. 
 
 With the parts before you, consider what would be the easiest 
 way of performing this operation. Several modes have been 
 recommended. Upon the whole, the best authorities* agree that 
 the artery is most accessible from behind. An incision should 'be 
 made perpendicularly from the end of the last rib to the ilium ; 
 another transversely along the margin of this bone nearly to its 
 spine. We then cut, layer after layer, through the abdominal 
 muscles till the peritoneum is exposed ; this is easily raised from 
 the iliac fascia, and with it the ureter is raised too. The applica- 
 tion of the ligature is, after all, the most delicate part of the 
 operation. It ought to be placed, as near as possible, midway 
 between the origin and the division of the artery, so that there 
 may be room enough for the formation of a clot on either side.f 
 
 This artery passes along the brim of the pelvis, on 
 
 IMAC ARTERY. * ne i nner side of the psoas, and then running under 
 
 the crural arch about midway between the spine of the 
 
 ilium and the symphysis pubis, takes the name of femoral. The 
 
 corresponding vein lies close to its inner side, and on a posterior 
 
 * Consult some observations in point by Sir P. Crampton, in Med. Chir. Trans, 
 vol. xvi. 
 
 f It is important to be aware that the length of the common iliac artery is apt 
 to vary in different persons. I have seen it from three-fourths of an inch to three 
 and a half inches long. These varieties may arise either from a high division of the 
 aorta, or a low division of the common iliac, or both. It is impossible to ascertain, 
 beforehand, what will be its length in a given instance, for there is no necessary 
 relation between its length and the height of the adult individual. It is often very 
 short in men of tall stature, and vice versa. Anatomists generally describe the left as 
 rather longer than the right; but, from the examination of 100 bodies, I conclude that 
 their average length is the same. 
 
EXTERNAL ILIAC ARTERY. 355 
 
 plane. The artery, with its vein, is bound down upon the psoas 
 by a thin layer of fascia derived from the iliac. There are two 
 other circumstances of practical interest respecting this artery: 
 
 1. A slender nerve, the genito-crural, runs close to its outer side; 
 
 2. Just before it leaves the pelvis it is crossed by the circumflexa 
 ilii vein. The branches given off by this artery are : 
 
 The epigastric, already described (p. 322). 
 
 The circumflexa ilii, which arises just above the crural arch, 
 and running towards the spine of the ilium in a sheath formed for 
 it by the fascia iliaca, subsequently perforates the transversalis 
 muscle.* In the dissection of the abdominal muscles (p. 3 13), the 
 continuation of it was seen skirting the crest of the ilium between 
 the internal oblique and the transversalis, and sending a branch 
 upwards between these muscles for their supply. The main trunk, 
 much reduced in size, inosculates with the ilio-lumbar derived 
 from the internal iliac. 
 
 How to tie ^ ne eas i es t wa J f tying the external iliac is to make 
 the external a curved incision at the lower part of the abdomen, 
 beginning a little above the middle of the crural arch, 
 and ending a little beyond the spine of the ilium. The strata of 
 the abdominal muscles, with the fascia transversalis, should then 
 be divided to the same extent ; after which, the peritoneum must 
 be separated by the fingers from the iliac fossa. It is necessary to 
 make a small incision through the sheath of the vessel, to facilitate 
 the passage of the needle. Kemember that the vein is closely 
 connected to its inner side,f and that the genito-crural nerve is 
 not far off. 
 
 * The course of this artery should be borne in mind in opening iliac abscesses. 
 
 t This relative position of the vessels must not always be taken for granted. In 
 old subjects, less frequently in adults, it is sometimes found that the external iliac 
 artery runs very tortuously, instead of nearly straight, along the brim of the pelvis. 
 But the vein does not follow the artery in its windings, and may possibly lie outside 
 the artery just where we propose to place the ligature. 
 
 The mode of performing the operation described in the text is recommended by 
 Sir A. Cooper. Mr. Abernethy, however, who first set the example of tying this 
 artery, in 1796, adopted a somewhat different proceeding. He says: 'I first made 
 an incision about three inches in length through the integuments of the abdomen, in 
 
 A A 2 
 
356 LUMBAR PLEXUS. 
 
 The general plan upon which the sympathetic nerve 
 
 rHETXG ifl 
 NERVE. 
 
 SYMPATHETIC - g arran g e( j j nas been noticed in the dissection of the 
 
 neck (p. 99). The lumbar portion of it must now be 
 examined. 
 
 The abdominal part of the sympathetic descends on either side, 
 in front of the bodies of the lumbar vertebras, along the inner 
 border of the psoas. The nerve has a ganglion opposite each 
 lumbar vertebra, so that there are five on each side. These 
 ganglia are connected with one another by small filaments, and 
 each ganglion receives two branches from the corresponding spinal 
 nerve, just as in the chest. They give off filaments, of which 
 some twine round the aorta, and accompany the inferior mesenteric 
 and spermatic arteries to the large intestine and the testicle ; but 
 the greater number terminate in the hypogastric plexus. 
 
 The hypogastric plexus is situated between the com- 
 Hypogastnc mon ^j ac ar teries, on the last lumbar and first sacral 
 
 plexus. 
 
 vertebras. It consists of an inextricable interlacement 
 of nerves, partly sympathetic, and partly spinal, and is a sort of 
 nerve centre for the supply of the pelvic viscera. Tracing it for- 
 wards, you find that it is continued on in two divisions, one for 
 each side of the pelvis. The minute filaments proceeding from 
 each division accompany the visceral branches of the internal iliac 
 artery of their respective sides, and supply the bladder, prostate 
 gland, and rectum ; and in the female, the uterus and vagina. 
 Thus we have the vesical, hasmorrhoidal, uterine, and vaginal 
 plexuses. Of these, however, none are seen in an ordinary dis- 
 section. No ganglia are found in the hypogastric plexus. 
 LUMBAR ^his plexus is formed by the union of the anterior 
 
 PLEXUS OF branches of the four upper lumbar nerves. The fifth 
 
 lumbar does not form part of this plexus, but joins 
 
 the direction of the artery, and thus laid bare the aponeurosis of the external oblique 
 muscle, which I next divided from its connection with Poupart's ligament, in the 
 direction of the external wound, for the extent of about two inches. The margins of 
 the internal oblique and transversalis muscles being thus exposed, I introduced my 
 finger beneath them for the protection of the peritoneum, and then divided them. 
 Next, with my hand, I pushed the peritoneum and its contents upwards and inwards, 
 and took hold of the artery.' 
 
LUMBAR PLEXUS. 357 
 
 the sacral plexus under the name of the lumbo-sacral cord. The 
 plexus lies over the transverse processes of the corresponding 
 vertebrae, embedded in the substance of the psoas, so that this 
 muscle must be dissected away before it can be seen. Like the 
 brachial plexus, the nerves composing it successively increase in 
 size from above. Its branches are five in number, and generally 
 arise in the following order (fig. 72). 
 
 The first lumbar nerve generally divides into two branches ; 
 the upper being commonly the ilio-hypogastric, the lower, the 
 ilio-inguinal. They cross obliquely over the quadratus lumborum 
 to the crest of the ilium, and then separate. The ilio-hypogastric 
 passes through the transversalis, and divides into its two terminal 
 branches; the iliac branch, which supplies the skin over the 
 glutseal region, and the hypogastric branch, which runs forwards 
 between the transversalis and internal oblique, and then perforates 
 the aponeurosis of the external oblique in the hypogastric region 
 to supply the skin. The ilio-inguinal perforates the transversalis 
 and internal oblique, comes out through the external abdominal 
 ring in front of the spermatic cord, and supplies the skin of the 
 penis and scrotum in the male, and the labium in the female. 
 
 The external cutaneous nerve of the thigh is generally derived 
 from the second lumbar. It runs through the psoas, then, crossing 
 obliquely over the iliacus towards the spine of the ilium, passes 
 beneath the crural arch, and is finally distributed to the skin on 
 the outside of the thigh. If the external cutaneous be not found 
 in its usual situation, look for it as a distinct branch of the anterior 
 crural, nearer the psoas muscle. 
 
 The genito-crural nerve is of small size, and generally comes 
 from the second lumbar. After perforating the psoas, it runs 
 down along the outer side of the external iliac artery, and near the 
 crural arch divides into the genital branch (g\ which runs through 
 the inguinal canal, on the under aspect of the spermatic cord, 
 and supplies the cremaster ; and the crural (e), which proceeds 
 under the crural arch, and is lost in the skin of the upper part 
 of the thigh, where it communicates with the middle cutaneous 
 nerve. 
 
358 
 
 LUMBAR PLEXUS. 
 
 The anterior crural (d\ the largest and most important branch, 
 is generally formed by the union of the third and fourth lumbar. 
 It descends in a groove between the psoas and the iliacus, supplies 
 both these muscles, and then, passing under the crural arch, is 
 finally distributed to the extensor muscles, to the sartorius and 
 pectineus, and the skin of the thigh. 
 
 Fig. 72. 
 
 a. Ilio-hypogastric n. 
 ft. Ilio-inguinal n. 
 
 c. External cutaneous n. 
 
 d. Anterior crural n. 
 
 e. Crural branch of genito- 
 
 crural n. 
 /. Obturator n. 
 g. Genital branch of genito- 
 
 crural n. 
 A. Lumbo-sacral n. 
 
 1. First lumbar n. 
 
 2. Second 
 
 3. Third 
 
 4. Fourth 
 
 5. Fifth 
 
 PLAN OF THE LUMBAR PLEXUS AND BRANCHES. 
 
 The obturator nerve (/) is next in size to the anterior crural. 
 It proceeds from the third and fourth lumbar nerves, descends 
 along the brim of the pelvis to the obturator foramen, and is dis- 
 tributed to the adductor muscles of the thigh. 
 
 The accessory obturator nerve is by no means a constant branch, 
 but when present, comes from the obturator or third and fourth 
 lumbar nerves. It descends over the horizontal ramus of the 
 pubes, and supplies the pectineus on its under aspect. 
 
DISSECTION OP THE PELVIS. 359 
 
 Postponing the minute anatomy of the abdominal viscera, begin 
 the examination of the contents of the pelvis. 
 
 DISSECTION OF THE PELVIS. 
 
 The purposes of the pelvis are to protect its own viscera; to 
 support those of the abdomen ; to give attachment to the muscles 
 which steady the trunk ; to transmit the weight of the trunk to 
 the lower limbs, and to give origin to the muscles which move 
 them. In adaptation to these functions, the form of the pelvis is 
 that of a perfect arch, with broadly expanded wings at the sides, 
 and projections in appropriate situations to increase the leverage 
 of the muscles. The sacrum, impacted between the ilia, repre- 
 sents the key-stone of the arch, and is capable of supporting not 
 only the trunk, but great burdens besides. The sides or pillars 
 are represented by the ilia; these transmit the weight to the 
 heads of the thigh bones, and are thickest and strongest just in 
 that line, i.e. the brim of the pelvis, along which the weight is 
 transmitted. Moreover, to effect the direct transmission of the 
 weight, the plane of the arch is oblique. This obliquity of the 
 pelvis, its hollow expanded sides, its great width, the position and 
 strength of the tuberosities of the ischia, are so many proofs that 
 man is adapted to the erect posture. 
 
 The general conformation of the pelvis in the female is modified, 
 so as to be adapted to utero-gestation and parturition. Its breadth 
 and capacity are greater than in the male. Its depth is less. The 
 alse of the iliac bones are more expanded. The projection of the 
 sacrum is less perceptible, and consequently the brim is more 
 circular. Above all, the span of the pubic arch is wider. The 
 bones, too, are thinner, and the muscular impressions less strongly 
 marked. 
 
 The cavity of the pelvis being curved, the axis, or a central 
 line drawn through it, must be curved in proportion. For all 
 practical purposes, it is sufficient to remember that the axis of 
 
360 CONTENTS OF THE MALE PELVIS. 
 
 the pelvis corresponds with a line drawn from the anus to the 
 umbilicus.* 
 
 CONTENTS or ^ e ma ^ e pelvis contains the last part of the intestinal 
 THE MALE canal, named the ' rectum,' the bladder with the pros- 
 tate gland at the neck, and the vesiculse seminales. If 
 the bladder be empty, some of the small intestines will be in the 
 pelvis ; not so if the bladder be distended. 
 
 The rectum enters the pelvis on the left side of the 
 th^rectum sacrum, and, after describing a curve corresponding with 
 the concavity of the sacrum, terminates at the anus. 
 In the first part of its course, it is loosely connected to the back 
 of the pelvis by a peritoneal fold, called the ' mesa-rectum : ' be- 
 tween the layers of this fold the terminal branches (superior 
 haemorrhoidal) of the inferior mesenteric vessels with nerves and 
 absorbents run to the bowel. 
 
 It is worth remembering that the rectum does not take this 
 course in all cases ; sometimes it makes one, or even two lateral 
 curves. In some rare cases it enters the pelvis on the right side 
 instead of the left. Since these variations from the usual arrange- 
 ment cannot be ascertained during life, they should make us 
 cautious in the introduction of bougies. f 
 
 Whilst the parts are still undisturbed, introduce the 
 t what is called the recto-vesical peritoneal 
 pouch (fig. 73). This is a cul-de-sac formed by the 
 peritoneum in passing from the front of the rectum to the lower 
 and back part of the bladder. In the adult male subject, the 
 bottom of this pouch is about one inch distant from the base of the 
 
 * In a well-formed female the base of the sacrum is about four inches higher than 
 the upper part of the symphysis pubis, and the point of the coccyx is rather more than 
 half an inch higher than the lower part of the symphysis. 
 
 The obliquity of the pelvis is greatest in early life. In the foetus, and in young 
 children, its capacity is small ; and the viscera, which subsequently belong to it, are 
 situated in the abdomen. 
 
 t In old age the rectum has sometimes a zig-zag appearance immediately above the 
 anus. These lateral inclinations are probably produced by the enormous distentions 
 to which the bowel has been occasionally subjected. 
 
RECTO-VESICAL POUCH. 
 
 361 
 
 prostate gland : * therefore part of the under surface of the bladder 
 is not covered by peritoneum ; and since this part is in immediate 
 contact with the rectum, it is practicable to tap the distended 
 bladder through the front of the bowel without injuring the 
 peritoneum. The operation has, of late years, been revived, and 
 with great success.f It is easily done, and not attended with risk 5 
 provided all the parts be in their regular position. But this is 
 not always the case. It sometimes happens that the peritoneal 
 
 Fig. 73. 
 
 Symphysis pubis . 
 
 Corpus cavernosum 
 penis 
 
 Q-lans penis . . . 
 
 Corpus spongiosum 
 urethras. . . . 
 
 Bulb of corp. spon- 
 giosum . . . . 
 
 Covvper's gland with 
 duct 
 
 Membranous part 
 of urethra sur- 
 rounded by com- 
 pressor muscle. 
 
 Prostate gland 
 
 Peritoneum in dot- 
 ted outline. 
 
 Ureter. 
 
 Vas deferens. 
 Vesicula seminalis. 
 
 'Ul 
 
 
 
 DIAGRAM OF THE RELATIVE POSITION OF THE PELVIC VISCERA. 
 
 pouch comes down nearer to the prostate than usual we have 
 seen it in actual contact with the gland ; so that in such a case it 
 would be almost impossible to tap the bladder from the rectum 
 without going through the peritoneum. In children the peri- 
 toneum comes down lower than it does in the adult, because the 
 bladder in the child is not a pelvic viscus. 
 
 The recto- vesical pouch is permanent. But there is another 
 
 * The bottom of the pouch is from three to four inches distant from the anus, 
 t See a paper in the Med. Chir. Trans, vol. xxxv. by Mr. Cock. 
 
362 MALE PERINEUM. 
 
 peritoneal pouch on the front part of the bladder, which is only 
 produced when the bladder is distended. To produce it, the 
 bladder should be blown up through one of the ureters. It soon 
 fills the pelvis, and then, rising into the abdomen, occasions the 
 pouch in question between it and the abdominal wall. At first, 
 the pouch is shallow, but it gradually deepens as the bladder rises. 
 Now, if the bladder be distended half way up to the umbilicus, 
 which is commonly the case when it has to be tapped, we find that 
 the bottom of the pouch would be about two inches from the sym- 
 physis pubis (fig. 73). Within this distance from the symphysis, 
 the bladder may be tapped in the linea alba, without risk of 
 wounding the peritoneum. Thus, the surgeon has the choice of 
 two situations in which he may tap the bladder above the pubes, 
 or from the rectum. Which of the two be the more appropriate, 
 must be decided by the circumstances of the case. 
 
 DISSECTION OF THE MALE PERINEUM. 
 
 Before dissecting the perineum, it is expedient first to examine 
 the osseous and ligamentous boundaries of the lower aperture of 
 
 the pelvis. Looking at the male pelvis 
 (with the ligaments preserved), we ob- 
 serve that this aperture is of a lozenge 
 shape; that it is bounded in front by 
 the symphysis of the pubes, laterally by 
 the rami of the pubes and ischium ; be- 
 hind, by the coccyx and the great sacro- 
 ischiatic ligaments. 
 
 This space, for convenience of descrip- 
 tion, we divide into two by an imaginary 
 line drawn from one tuber ischii to the 
 
 DIAGRAM OF THE FRAMEWORK ., mi r i 
 
 OF THE PERINEUM. other. 1 he anterior lorms a nearly equi- 
 lateral triangle, of which the sides are 
 
 from three to three and a half inches long ; and since it trans- 
 mits the urethra, it is called the urethral divison of the perineum. 
 
MALE PEKINEUM. 363 
 
 The posterior, containing the anus, is called the anal division 
 (fig. 74). 
 
 The subject is to be placed in the usual position for lithotomy, 
 with a full-sized staff in the bladder, the rectum moderately dis- 
 tended with tow, and the scrotum raised by means of hooks. 
 Observe that a central ridge, named the 'raphe,' extends from 
 the anus, along the perineum, scrotum, and under surface of 
 the penis. Between the tuberosities of the ischia and the anus 
 are two depressions, marking out the ischio-rectal fossae, which 
 are found immediately beneath the skin, filled with fat. In 
 the lateral operation of lithotomy, the incision should commence 
 an inch and a quarter above the anus, close to the left side of the 
 raphe ; it should be carried downwards and outwards for three 
 inches, to a point midway between the tuber ischii and the anus. 
 In the bilateral operation, the incision is semi-lunar, the horns 
 being made on either side between the tuber ischii and the anus, 
 equidistant from these points respectively ; while the centre of the 
 incision runs about three-quarters of an inch above the anus. 
 
 At the anus the skin becomes finer and more deli-' 
 cate, forming a gradual transition towards mucous 
 membrane : during life it is drawn into wrinkles by the permanent 
 contraction of the cutaneous sphincter. Moreover, the skin at 
 the margin of the anus is richly provided with minute glands,f 
 which secrete an unctuous substance to facilitate the passage of the 
 faeces. When this secretion becomes defective or vitiated, the anal 
 cutaneous folds are apt to become excoriated, chapped, or fissured ; 
 and then defaecation becomes exceedingly painful. 
 
 The skin should be reflected, by making an incision 
 alon the ra P h > round the margin of the anus to the 
 coccyx. Two others must be made on each side at right 
 
 * It is well to bear in mind, that the dimensions of the lower outlet of the pelvis 
 are apt to vary in different subjects, and the lithotomist must modify his incisions 
 accordingly. 
 
 f These glands are the analogues of the anal glands in some animals, e.g. the dog 
 and the beaver. They are found not only about the amis, but also in the subcutaneous 
 tissue of the perineum, a fact for the demonstration of which we are indebted to 
 Professor Quekett. They are large enough to be seen with the naked eye. 
 
364 MALE PERINEUM. 
 
 angles to the first, the one at the upper, and the other at the lower 
 end of it. The skin of the perineum must then be reflected out- 
 wards. In reflecting the skin, we have to notice the characters of 
 the subcutaneous structure.* Its characters alter in adaptation to 
 the exigencies of each part. On the scrotum the fat constituent 
 of the tissue is entirely, and for obvious reasons, absent ; while the 
 fibro-cellular element is most abundant, and during life elastic 
 and contractile. But, as we recede from the scrotum, and ap- 
 proach the anus, the fat accumulates more and more, 
 
 Fat in ischio- an( j on e jther side of the rectum it is found in the shape 
 rectal fossae. L 
 
 of large masses, filling up what would otherwise be two 
 
 deep hollows in this situation namely, the ischio- rectal fossae. 
 These fossae are triangular, with their bases towards the skin, and 
 their apices at the divergence of the obturator internus and levator 
 ani. They are about two inches in depth, and are much deeper 
 posteriorly than in front. The purpose of this accumulation of fat 
 on each side of the anus, is to permit the easy distention and con- 
 traction of the lower end of the bowel during and after the passage 
 of the fasces.f Over the tuberosities of the ischia, we meet with 
 large masses of fat, separated by tough, fibrous septa, passing from 
 the skin to the bone, so as to make an elastic padding to sit upon. 
 Occasionally, too, there are one or more large bursce, interposed 
 between this padding and the bone. 
 
 So much respecting the general characters of the subcutaneous 
 tissue of the perineum. Some anatomists describe it as consisting 
 of three, four, or even more layers, but in nature we do not find 
 it so. It may, indeed, be divided into as many layers as we please, 
 according to our skill in dissection; but this only complicates 
 what is, in itself, simple. 
 
 * The probable thickness of this subcutaneous tissue is a point which ought to be 
 determined by the lithotomist in making his first incision. Its great thickness in 
 some cases explains the depth to which the surgeon has to cut in letting out matter 
 from the ischio-rectal fossa. 
 
 f It is this fat in the ischio-rectal. fossae which renders them so liable to the occur- 
 rence of peculiarly foatid gangrenous abscesses. These should be opened as early as 
 possible, lest they burst into the rectum ; and one sees how deep the knife must be 
 introduced, in order to reach the seat of the mischief. 
 
MALE PERINEUM. 365 
 
 The cutaneous sphincter ani must now be cleaned ; care being 
 taken not to remove any of its fibres. Posteriorly, the lower border 
 of the glutseus maximus must be displayed, and the vessels and 
 nerves crossing the perineum, towards the anus, carefully dis- 
 sected. 
 
 The cutaneous sphincter of the anus arises from the 
 
 Cutaneous 
 
 sphincter point of the coccyx, and from the ano-coccygeal liga- 
 am> ment. The muscular fibres surround the anus, and are 
 
 inserted in a pointed manner in the tendinous centre of the 
 perineum (p. 367). It is called the cutaneous sphincter, to dis- 
 tinguish it from a deeper and more powerful band of muscular 
 fibres which surrounds the last inch or more of the rectum, and is 
 situated nearer to the mucous membrane. 
 
 Cutaneous ^ e cu t aneous vessels and nerves of the perineum 
 
 vessels and come from the internal pudic artery and nerve, and 
 nerves. chiefly from that branch of it called the ( superficialis 
 
 perinei.' This will be traced presently. Besides this, a cutaneous 
 nerve is distributed to these parts from the lesser ischiatic, called 
 the long pudendal nerve (p. 367). It comes through the muscular 
 fascia of the thigh a little above the tuber ischii, and ascends, 
 dividing into filaments, which supply the skin of the perineum 
 and scrotum. 
 
 Crossing transversely through the ischio -rectal fossa, from the 
 ramus of the ischium towards the anus, are the external or in- 
 ferior hcemorrhoidal arteries. These come from the pudic (which 
 may be felt on the inner side of the ischium), and running in- 
 wards, supply the rectum, levator ani, and sphincter ani. The 
 nerve which accompanies the artery comes from the pudic, and 
 supplies the sphincter ani and the skin of the perineum. 
 
 er fi j. i The subcutaneous fascia of the perineum is composed 
 or muscular of a superficial and a deep layer. The superficial 
 fascia of the j aver contains more or less fat, and is continuous with 
 
 perineum. J 
 
 that of the scrotum, the thighs, and the posterior part 
 of the perineum. The deeper layer is best demonstrated by blow- 
 ing air beneath it with a blow-pipe ; its connections are as follow : 
 It is attached on either side to the anterior lip of the ramus of 
 
366 MALE PERINEUM. 
 
 the pubes and ischium ; traced forwards, it is directly continuous 
 with the tunica dartos of the scrotum ; traced backwards, we find 
 that at the base of the urethral triangle it is reflected beneath the 
 trans versus perinei muscle, and joins the ' deep perineal fascia' 
 or * triangular ligament.' These connections explain the reason 
 why urine effused into the perineum, does not make its way into 
 the ischio-rectal fossae, or down the thighs. 
 
 Remove the fascia to see the muscles which cover the bulb of 
 the urethra and the crura of the penis. The bulb of the urethra 
 lies in the middle of the perineum, and is covered by a strong 
 muscle, called ' accelerator urinse.' The crura penis are attached, 
 one to each side of the pubic arch, and are covered each by a 
 muscle, called ( erector penis.' A narrow slip of muscle, called 
 * transversus perinei,' extends on either side from the tuber ischii 
 to the central tendinous point of the perineum. This point is 
 about one inch and a quarter in front of the anus, and serves for 
 the attachment of muscular fibres from all quarters of the peri- 
 neum. 
 
 Thus the muscles of the perineum describe on each side a 
 triangle, of which the sides are formed by the accelerator urinae 
 and the crus penis respectively, and the base by the transversus 
 perinei. Across this triangle run up from base to apex the super- 
 ficial perineal vessels and nerves. External to the ramus of the 
 ischium is seen a nerve, the long pudendal, a branch of the lesser 
 ischiatic, perforating the muscular fascia of the thigh. 
 Su erficial ^^ e su P er fi G ^ p&rineol artery proceeds from the 
 perineal internal pudic as it runs up the inner side of the tuber 
 nerves 8 ^ ^ scm ^ Though the main trunk cannot be seen, it can 
 be easily felt by pressing the finger against the bone. 
 The artery comes into view a little above the level of the anus, 
 and then passes up the perineal triangle, distributing branches to 
 all the muscles, and is finally lost on the scrotum. The only 
 named branch is a muscular one, called ( transversalis perinei ' 
 (p, 367). This is given off near the base of the triangle, and runs 
 with the transversus perinei muscle towards the central point of 
 the perineum. It is necessarily divided in the first incision in 
 
MALE PERINEUM. 
 
 367 
 
 lithotomy, and deserves attention, because it is sometimes of con- 
 siderable size. 
 
 The artery is accompanied by two veins, which are frequently di- 
 lated and tortuous, especially in diseased conditions of the scrotum. 
 
 The nerves, two in number, are derived from the internal pudic, 
 follow the course of their corresponding arteries, and give off 
 
 Fig. 75. 
 
 Triangular liga- 
 ment . . 
 
 Tendinous centre 
 of the perineum 
 
 Transversus peri- 
 nci 
 
 Ischio-rectal fossa 
 
 Long pudendal n. 
 
 Transversalis 
 perinei a. 
 
 Superflcialis 
 
 perinei a. 
 External hae- 
 
 morrhoidal a. 
 
 MUSCLES, WITH SUPERFICIAL VESSELS AND NERVES, OF THE PERINEUM. 
 
 similar branches. They not only supply the skin of the perineum 
 and scrotum, but each of the permeal muscles. 
 
 The long pudendal nerve, a branch of the lesser ischiatic, 
 
368 
 
 MALE PERINEUM. 
 
 makes its exit through the muscular fascia of the thigh, a little 
 above the tuber ischii. It ascends nearly parallel to the ramus of 
 the ischium and pubes, and dividing into filaments, supplies the 
 skin of the perineum and scrotum. 
 
 This muscle embraces the bulb of the urethra. It, 
 Accelerator ar i ses f rO m a fibrous median raphe beneath the bulb, 
 and from the tendinous centre of the perineum. Start- 
 ing from this origin, the fibres diverge and are inserted as follows : 
 The upper ones proceed on either side round the corpus caver- 
 Fig. 76. 
 
 Corpus cavernosum 
 Corpus spongiosum 
 
 Upper fibres 
 Middle fibres 
 
 Lower fibres 
 
 Tendinous centre of perineum 
 
 OWPERS c uN 
 TRIANGULAR 
 L 'CAMENT 
 
 DIAGRAM TO SHOW THE ACCELERATOR URINJE IN PROFILE. 
 
 nosum penis, like the branches of the letter V, and are fixed on its 
 upper surface: the middle completely embrace the bulb, like a 
 ring, and meet in a tendon on the upper surface of the urethra ; 
 the lower are fixed to the anterior surface of the deep perineal 
 fascia (fig. 76). 
 
 Thus, the entire muscle acts as a powerful compressor of the 
 bulb, and expels the last drops of urine from this part of the 
 urethra. By dividing the muscle along the middle line and turn- 
 ing back each half, its insertion, as above described, can be clearly 
 made out. 
 
MALE PERINEUM. 369 
 
 These muscles are moulded, one upon each crus of 
 Erectores ^ e p en { s> Each muscle arises from the inner surface 
 of the tuber ischii ; the fibres ascend, completely cover- 
 ing the crus, and terminate on a strong aponeurosis, which is 
 inserted into the external and inferior aspect of the crus. The 
 action of these muscles is to compress the root of the penis, and 
 so to contribute to the erection of the organ. 
 
 These muscles are of insignificant size, and sometimes 
 
 al:)sent - Tne J arise > one on eacn side > from tne tuber 
 
 ischii, and proceed towards the central point of the 
 perineum, where they are blended with the fibres of the accelerator 
 urinse. This muscle with its artery is divided in lithotomy. 
 
 The next stage of the dissection consists in reflecting and re- 
 moving the accelerator urinse from the bulb of the urethra, the 
 erector penis with the crus penis from the rami of the pubes and 
 ischium, and the transversi perinei muscles. This done, the 
 triangular ligament or ' deep perineal fascia ' is fairly exposed. 
 Trian ular Understand that the ' triangular ligament of the 
 ligament of urethra ' and the deep perineal fascia are synonymous 
 
 the urethra. termSt 
 
 The triangular ligament, shown in fig. 77, is a strong and re- 
 sisting membrane stretched across the upper pa,rt of the pubic 
 arch. On each side it is firmly attached to the posterior lip of 
 the rami of the pubes and ischium ; superiorly, i.e. towards the 
 symphysis of the pubes, it is connected with the sub-pubic liga- 
 ment ; inferiorly, it does not present a free border, but is connected 
 to the tendinous centre of the perineum, and becomes identified 
 with the deep layer of the superficial perineal fascia under the 
 transversus perinei muscle (p. 367). This ligament, by most 
 anatomists, is described as composed of two layers, an anterior 
 and a posterior, between which the membranous portion of the 
 urethra is situated. The anterior layer becomes continuous below 
 with the superficial perineal fascia; the posterior is a part of the 
 pelvic fascia, and is lost upon the prostate. 
 
 The membranous part of the urethra runs through the triangular 
 ligament about one inch below the symphysis pubis. The aperture 
 
 B B 
 
370 
 
 MALE PERINEUM. 
 
 for it does not present a distinct edge, because the ligament is 
 prolonged forwards over the bulb, and serves to keep it in 
 position. 
 
 Fig. 77. 
 
 Crus penis .... 
 
 Crus penis with its ar- 
 tery cut through . 
 
 Bamus of the pubes 
 
 Artery of the bulb . 
 Cowper's gland . . 
 Pudic artery . . . 
 
 Tuber ischii . 
 
 DIAGRAM TO SHOW THE TRIANGULAR LIGAMENT OF THE URETHRA. 
 
 Points of sur- The triangular ligament is very important surgically 
 gical interest. f or these reasons : 
 
 1. Here we meet with difficulty in introducing a catheter, unless 
 we can hit off the right track through the ligament. The soft 
 and spongy tissue of the bulbous part of the urethra in front of 
 
MALE PERINEUM. 
 
 371 
 
 the ligament readily gives way, if violence be used, and a false 
 passage results. 
 
 Fig. 78. 
 
 Compressor urethras . . 
 
 Membranous part of the 
 urethra surrounded by 
 its compressor muscle. 
 
 Prostate gland . . . . 
 
 Anterior fibres of the le- 
 vator ani . 
 
 DIAGRAM OF THE PARTS BEHIND THE TRIANGULAR LIGAMENT OF THE URETHRA. 
 
 (The anterior fibres of the levator ani are hooked clown to show part of the prostate ; 
 the rest is tracked by a dotted line.) 
 
 2. By elongating the penis, we are much more likely to hit off 
 the proper opening through the ligament. 
 
 3. When, in retention of urine, the urethra gives way anterior 
 
 B 2 
 
372 MALE PERINEUM. 
 
 to this ligament, it is this which prevents the urine from travel- 
 ling into the pelvis. Its connection with the superficial perineal 
 fascia prevents the urine from getting into the ischio-rectal fossa : 
 nor can the urine make its way into the thighs. The only outlet 
 for it is into the cellular tissue of the scrotum and penis. 
 
 4. When suppuration takes place behind the ligament, the 
 matter is pent up and should be speedily let out ; if not, it will 
 find its way into the cellular tissue of the pelvis and may burst 
 into the urethra or the rectum. 
 
 5. The ligament is partially cut through in lithotomy. 
 
 The parts divided in the lateral operation of lithotomy are : the 
 skin, the superficial fascia, the transverse perineal muscle, vessels 
 and nerve ; the accelerator urinee, the anterior fibres of the leva- 
 tor ani, the compressor urethrse, the triangular ligament, the mem- 
 branous and prostatic parts of the urethra, and a small portion of 
 the prostate. 
 
 The anterior layer of the triangular ligament must 
 What lies now ^ Q cu f. awav ^ see w h a t lies behind it. These parts 
 
 between the 
 
 layers of the are shown in fig. 78 ; namely : 1, the membranous part of 
 the urethra, surrounded by, 2, the compressor urethras 
 muscle; 3, Cowper's glands; 4, the pudic artery and 
 its three terminal branches, i.e. the artery of the bulb, the artery 
 of the crus, and the dorsal artery of the penis. 
 
 ( To obtain the best perineal view of the compressor urethraa 
 muscle, cut through the spongy part of the urethra about three 
 inches above the end of the bulb, and dissect it from the corpus 
 cavernosum. Thus, the upper fibres of the constrictor will be 
 exposed ; to see the lower, it is only necessary to raise the bulb. 
 The most perfect view, however, of the muscle is obtained by 
 making a transverse section through the rami of the pubes, so as 
 to get at the muscle from above, as shown in fig. 79. 
 
 This muscle surrounds and supports the urethra in 
 ** s P assa g e beneath the pubic arch. It arises from the 
 rarnus of the pubes on either side; from thence its 
 fibres pass, some above, some below the urethra, along the whole 
 length of its membranous part. It forms a complete muscular 
 
MALE PERINEUM. 
 
 373 
 
 covering for the urethra between the prostate and the bulb. It is 
 chiefly through its agency that we retain the urine. This muscle 
 is the chief cause of spasmodic stricture of the urethra.* 
 
 Fig. 79. 
 
 Catheter 
 
 Dorsal nerve of the penis . 
 Dorsal artery of the penis . 
 Dorsal vein of the penis . 
 
 Anterior layer of triangular 
 ligament 
 
 Bam us of pubes cut through 
 
 Posterior layer of triangular 
 
 ligament : part of the 
 
 pelvic fascia 
 
 i 
 
 ! j 
 DIAGRAM OF THE RELATIONS OF THE COMPRESSOR URETHRA SEEN FROM ABOVE. 
 
 * The compressor urethrse was first accurately described and delineated by Santorini 
 (septemdec. tabulae), and afterwards by Miiller in his monograph (Ueber die organ. 
 Nerv. der mannlich. Greschlechtsorgane). 
 
374 MALE PEKINEUM. 
 
 These glands are imbedded, one on either side, im- 
 Cowper s mediately behind the bulb, in the substance of the com- 
 pressor urethrae. Each consists of a cluster of little 
 glands. Their collective size is about that of a pea, but it varies 
 in different individuals. From each a slender duct runs forwards, 
 and, after a course of about one inch, opens into the under surface 
 of the bulbous part of the urethra (p. 377). Their use is to furnish 
 a secretion accessory to generation. 
 
 Pudic arte ^ ne P a ^ c ar t er j is a branch of the internal iliac. 
 and its It leaves the pelvis through the great ischiatic notch, 
 
 ranches. winds round the spine of the ischium, re-enters the 
 pelvis through the lesser ischiatic notch, and then runs along the 
 inner side of the tuber ischii up towards the pubic arch. About 
 an inch and a half above the tuber ischii, we can feel the trunk of 
 the pudic artery; but we cannot see it, nor draw it out, for it is 
 securely lodged in a fibrous canal formed by the obturator fascia. 
 Traced upwards, it runs between the two layers of the triangular 
 ligament, and divides into three principal branches ; the artery of 
 the bulb, the artery of the crus, and the dorsal artery of the penis 
 (fig. 78). The external hsemorrhoidal and superficial perineal 
 branches have already been described (p. 366). 
 
 The artery of the bulb is of considerable size, and passes trans- 
 versely inwards ; it runs through the substance of the compressor 
 urethrse, and before it enters the bulb divides into two or three 
 branches. It also sends a small branch to Cowper's gland. From 
 the direction of this artery it will at once strike the attention that 
 there is great risk of dividing it in lithotomy. If the artery run 
 along its usual level, and the incision be not made too high in the 
 perineum, then indeed it is out of the way of harm. But, sup- 
 posing the reverse, the artery cannot escape ; and its size is such 
 that it might occasion alarming haemorrhage. If it be asked, how 
 often does the artery run along a dangerous level ? about once in 
 twenty subjects; and there is no possibility of ascertaining this 
 anomaly beforehand. 
 
 The artery of the crus penis is given off after that of the bulb. 
 
MALE PERINEUM. 375 
 
 It ascends for a short distance under cover of the arch, but soon 
 enters the crus. 
 
 To see the dorsal artery of the penis, the penis must be dis- 
 sected from its attachment to the symphysis pubis. The artery 
 should be traced running upon the dorsum of the penis down to 
 the glans. It forms a complete arterial circle round the corona 
 glandis, and gives numerous ramifications to the papillae on the 
 surface. 
 
 The pudic nerve comes from the sacral plexus, and 
 corresponds both in its course and branches with the 
 artery. It gives off its external or inferior hsemorrhoidal, and its 
 superficial perineal branches a small one to the bulb, and another 
 to the crus penis ; but the main trunk of the nerve runs with the 
 artery along the dorsum of the penis to the glans (p. 373). In its 
 passage it supplies the integuments of the penis, and sends one or 
 two branches into the corpus cavernosum. This part of the penis 
 also receives nerves from the sympathetic system. 
 
 This is the deep hollow on each side between the 
 lscHio-RECTAL anug an( j ^e tuber ischii. When all the fat is removed 
 from it, observe that it is lined on all sides by fascia. 
 Introduce the finger into it to form a correct idea of its extent and 
 boundaries. Externally, it is bounded by the tuber ischii and 
 the fascia covering the obturator internus muscle ; internally, by 
 the rectum, levator ani and coccygeus ; posteriorly, by the glutseus 
 maximus; anteriorly, by the transversus perinei. The fossa is 
 crossed by the external haemorrhoidal vessels and nerves. 
 
 These deep recesses on each side of the rectum explain the great 
 size which abscesses in this situation may attain. The matter can 
 be felt only through the rectum. Nothing can be seen outside. 
 Perhaps nothing more than a little hardness can be felt by the 
 side of the anus. These abscesses should be opened early ; else 
 they form a large cavity, and may burst into the rectum. 
 
376 SIDE VIEW OF THE PELVIC VISCERA. 
 
 ANATOMY OF THE SIDE VIEW OF THE PELVIC VISCEKA. 
 
 To make a side view of the pelvic viscera, the left innominate 
 bone should be removed thus : Detach the peritoneum and the 
 levator ani from the left side of the pelvis ; saw through the pubes 
 about two inches external to the symphysis, and cut through the 
 sacro-iliac symphysis ; now draw the legs apart, and saw through 
 the base of the spine of the ischium; after cutting through the 
 pyriformis, the great sacro-ischiatic ligament and ischiatic nerves, 
 the innominate bone can be easily detached. This done, the 
 rectum should be distended with tow, and the bladder blown up 
 through the ureter. A staff should be passed through the urethra 
 into the bladder. 
 
 You have already seen how the peritoneum passes from the 
 front of the rectum to the lower part of the bladder (forming the 
 recto- vesical pouch), and thence over the back of the bladder to 
 the wall of the abdomen. You see where the distended bladder is 
 bare of peritoneum, and that it can be tapped either through the 
 rectum or above the pubes without injury to the serous membrane, 
 as shown by the arrows in fig. 80. 
 
 False lisa- ^ ie P er ^ onea l connections of the bladder are called 
 ments of the its false ligaments ; false in contradistinction to the 
 bladder. true, which are formed by the fascia of the plevis, and 
 really do fasten the neck of the bladder in its proper position. 
 The false ligaments are five in number, two posterior, two lateral, 
 and one superior. The posterior are produced by two peritoneal 
 folds, one on either side the recto-vesical pouch, over the fibrous 
 remains of the umbilical arteries ; the two lateral by reflections of 
 the peritoneum from the side of the pelvis to the side of the 
 bladder ; the superior is produced by the passage of the peritoneum 
 to the abdominal wall, and contains the urachus and obliterated 
 umbilical arteries. 
 
 To expose the pelvic fascia, the peritoneum must be 
 Pelvic fascia. . r _f ' : r 
 
 removed from that side of the pelvis which has not 
 
 I 
 
 X 
 
SIDE VIEW OF THE PELVIC VISCERA. 
 
 377 
 
 been disturbed : in doing so, notice the abundance of loose cellular 
 tissue interposed between the peritoneum and the fascia, to allow 
 the bladder to distend with facility. Whenever urine gains access 
 to this cellular tissue, it is sure to produce the most disastrous 
 consequences ; therefore in all operations on the perineum, it is of 
 the utmost importance not to injure this fascia. 
 
 Fig. 80. 
 
 Peritoneum in dot- 
 ted outline . . . 
 
 Corpus cavernosum 
 penis 
 
 Triangular liga- 
 ment 
 
 Catheter in the 
 urethra .... LL 
 
 Bulb of the urethra 
 
 Cowper's gland with 
 duct 
 
 Prostate . 
 
 VERTICAL SECTION THROUGH THE PERINEUM AND PELVIC VISCERA. 
 
 The pelvic fascia is a thin but strong membrane, and constitutes 
 the true ligaments of the bladder, and the other pelvic viscera, 
 supporting and maintaining them in their proper position. 
 
 Examine first, to what parts of the pelvis the fascia is attached ; 
 secondly, the manner in which it is reflected on the viscera. 
 
 Beginning, then, in front (fig. 81), the fascia is attached to the 
 body of the pubes ; thence, we trace its attachment along the side 
 
378 
 
 SIDE VIEW OF THE PELVIC VISCERA. 
 
 of the pelvis, just above the obturator foramen, to the greater 
 ischiatic notch : here it becomes gradually thinner, covers the 
 pyriformis muscle, and is lost on the sacrum. From this attach- 
 ment the fascia descends as far as a line drawn from the spine of 
 the ischium to the symphysis pubis. Along this line, which corre- 
 
 Fig. 81. 
 
 --Iliac fascia. 
 
 Pelvic fascia. 
 
 Obturator fascia. 
 
 Pelvic fascia 
 covering over 
 levator ani. 
 
 Anal fascia. 
 
 TRANSVERSE SECTION OF THE PELVIS, TO SHOW THE REFLECTIONS OF 
 
 THE PELVIC FASCIA. (After Gray.} 
 
 sponds with the origin of some of the fibres of the levator ani, the 
 fascia divides into two layers, an inner, called the recto-vesical 
 fascia; an outer, called the obturator fascia. 
 
 The obturator fascia is the continuation of the pelvic fascia, 
 and runs down on the inner surface of the obturator internus, 
 
SIDE VIEW OF THE PELVIC VISCERA. 379 
 
 formiDg, at the same time, a sheath for the pudic vessels and 
 nerve. It is attached to the arch of the pubes, and to the tuber- 
 osities of the ischia. From this fascia is derived the anal fascia 
 which lines the lower surface of the levator ani, and is subse- 
 quently lost upon the rectum. 
 
 The recto-vesical fascia descends on the upper or internal sur- 
 face of the levator ani to the bladder and prostate. From the 
 pubes it is reflected over the prostate and the neck of the bladder, 
 to form, on either side of the symphysis, two well-marked bands 
 the anterior true ligaments of the bladder. From the side of the 
 pelvis it is reflected on to the side of the bladder, constituting the 
 lateral true ligaments of the bladder, and incloses the prostate 
 and the vesical plexus of veins. A prolongation from this liga- 
 ment incloses the vesicula seminalis, and then passes between the 
 bladder and the rectum, to join its fellow from the opposite sides. 
 The pelvic viscera are so surrounded by veins and 
 loose areolar tissue, that he who dissects them for the 
 
 POSITION OF 
 
 THE PELVIC first time will find a difficulty in discovering their 
 definite boundaries. The rectum runs at the back of 
 
 the pelvis. The bladder lies in front of the rectum, 
 immediately behind the symphysis pubis. At the neck of the 
 bladder is the prostate gland through which the urethra passes. 
 In the cellular tissue, between the bladder and the rectum, there 
 is, on each side, a convoluted tube called the ' vesicula seminalis ; ' 
 and on the inner side of each vesicula, is the seminal duct or vas 
 deferens. Before describing these parts in detail, it is necessary 
 to say a few words about the large tortuous veins which surround 
 them. 
 
 Beneath the pelvic fascia about the prostate and the 
 
 nec k of t ne bladder, are large and tortuous veins, which 
 prostate and form the prostatic and the vesical plexuses. They 
 bladder empty themselves into the internal iliac. In early life 
 
 they are not much developed, but as puberty ap- 
 proaches, they gradually increase in size; and one not familiar 
 with the anatomy of these parts would hardly credit the volume 
 which they sometimes attain in old persons. They communicate 
 
380 
 
 SIDE VIEW OF THE PELVIC VISCERA. 
 
 freely with the inferior heemorrhoidal plexus, or veins about the 
 anus, and they receive the blood returning from the penis through 
 the large veins which pass under the pubic arch. This is one of 
 the reasons why the prostatic plexus is so capacious. 
 
 Fig. 82. 
 
 SIDE VIEW OF THE PELVIC VISCEBA. 
 (Taken from a Photograph.) 
 
 - 1. External sphincter. 
 
 2. Internal sphincter. 
 
 3. Levator ani cut through. ' 
 
 4. Accelerator urinae. 
 
 5. Membranous part of the urethra, sur- 
 
 rounded by compressor muscle. 
 
 6. Prostate gland. 
 
 7. Vesicula seminalis. 
 
 8. Ureter. 
 
 9. Vasdeferens. 
 
 10. Crus penis divided. 
 
 11. Triangular ligament. 
 
 12. Superficial perineal fascia. 
 
 13. Rectum. 
 
 If, in lithotomy, the incision be carried beyond the limits of 
 the prostate, the great veins around it must necessarily be divided : 
 these, independently of any artery, are quite sufficient to occasion 
 serious haemorrhage. 
 
SIDE VIEW OF THE PELVIC VISCERA. 381 
 
 Rectum ^ e rec ^ um enters the pelvis on the left of the sacrum, 
 
 intestinum and describes a curve corresponding to the axis of the 
 relations pelvis. Before its termination, the bowel curves down- 
 wards so that the anal aperture is dependent. The 
 rectum is not throughout of equal calibre. Its capacity becomes 
 greater as it descends into the pelvis : and, immediately above the 
 sphincter, it presents a considerable dilatation (fig. 80). This 
 dilatation is not material in early life, but it increases as age 
 advances. An adequate idea of it cannot be formed unless the 
 bowel be fully distended. Under such circumstances the rectum 
 loses altogether its cylindrical form, and bulges up on either side 
 of the prostate and the base of the bladder. For this reason the 
 rectum should always be emptied before the operation of litho- 
 tomy. 
 
 The upper part of the rectum is connected to the sacrum by a 
 fold of peritoneum termed ' mesa-rectum.' In this fold, the 
 terminal branch of the inferior mesenteric artery with its vein 
 runs up to supply the bowel. Below the meso-rectum, the gut is 
 connected to the sacrum and coccyx by loose cellular tissue, which 
 allows its easy distention. The rectum is supported by the leva- 
 tores ani, the larger portions of which are inserted into its side. 
 
 The relations of the front part of the rectum, that, namely, 
 included between the recto-vesical pouch and the anus are most 
 important. Supposing the forefinger to be introduced into the 
 anus, and a catheter in the urethra, the first thing felt through 
 the front wall of the bowel is the membranous part of the urethra 
 (fig. 82). It lies just within the sphincter, and is about ten lines 
 in front of the gut. About one and a half or two inches from the 
 anus the finger comes upon the prostate gland ; this is in close 
 contact with the gut, and is readily felt on account of its hard- 
 ness ; by moving the finger from side to side we recognise its 
 lateral lobes. Still higher up, the finger goes beyond the prostate, 
 and reaches the ' trigone ' of the bladder : the facility with which 
 this can be examined depends not only upon the length of the 
 finger and the amount of fat in the perineum, but upon the degree 
 of distention of the bladder ; the more distended the bladder, the 
 
382 SIDE VIEW OF THE PELVIC VISCERA. 
 
 better can the prostate be felt. These several relations are practi- 
 cally important. They explain why, with the finger in the rectum, 
 we can ascertain whether the catheter is taking the right direction, 
 whether the prostate be enlarged or not. We might even raise 
 a stone from the bottom of the bladder so as to bring it in contact 
 with the forceps. The rectum is supplied with blood by the 
 superior, middle, and inferior hsemorrhoidal arteries. The superior 
 come from the inferior mesenteric (p. 341); the middle and in- 
 ferior from the pudic artery. The superior and middle hsemor- 
 rhoidal veins join the inferior mesenteric, and consequently the 
 portal system; the inferior haemorrhoidal veins join the internal 
 pudic. They are very large and form a very tortuous plexus about 
 the lower part of the rectum. Having no valves, they are liable 
 to become dilated and congested from various internal causes; 
 hence the frequency of haemorrhoidal affections. 
 
 This viscus, being a receptacle for the urine, must 
 necessarily vary in size, and accordingly the nature of 
 its connections and coats are such as to permit this variation. 
 When contracted, the bladder sinks into the pelvis behind the 
 pubic arch, and is completely protected from injury. But, as it 
 gradually distends, it rises out of the pelvis into the abdomen, 
 and, in cases of extreme distention, may reach nearly up to the 
 umbilicus.* Its outline can then be easily felt through the walls 
 of the abdomen. The form f of the distended bladder is oval, and 
 its long axis, if produced, would pass superiorly through the 
 umbilicus, and inferiorly through the end of the coccyx. The 
 
 * When the bladder is completely paralysed it becomes like an inorganic sac, and 
 there seems to be no limit to its distention. Haller found in a drunkard the bladder 
 so dilated that it would hold twenty pints of water. (Elem. Phys. art. Vesica.) 
 Frank saw a bladder so distended as to resemble ascites, and evacuated from it twelve 
 pounds of urine. (Oratio de Signis morborum, &c. &c. Ticini, 1788.) 
 
 W. Hunter, in his Anatomy of the Gravid Uterus, has given the representation of a 
 bladder distended nearly as high as the ensiform cartilage. 
 
 f In all animals with a bladder, the younger the animal the more elongated is the 
 bladder. This is indicative of its original derivation from a tube, i.e. the urachus. 
 In the infant, the bladder is of a pyriform shape, as it is, permanently, in the quad- 
 ruped ; but as we assume more and more the perpendicular attitude, the weight of the 
 urine gradually makes the lower part more capacious. 
 
SIDE VIEW OF THE PELVIC VISCERA. 383 
 
 axis of a child's bladder is more vertical than in the adult ; for in 
 children, the bladder is not a pelvic viscus. This makes lithotomy 
 in them so much more difficult. 
 
 The quantity of urine which the bladder will hold without much* 
 inconvenience varies. As a general rule it may be stated at about 
 a pint. A good deal depends upon the habits of the individual ; 
 but some persons have, naturally, a very small bladder, and are 
 obliged to empty it more frequently. 
 
 In young persons the lowest part of the bladder is the neck, or 
 that part which joins the prostate. But as age advances, the 
 
 Fig. 83. 
 
 :%&. - ' 4 - Tri *" e - 
 
 3. Vesicula seminalis. 
 
 POSTERIOR VIEW OF THE BLADDER. 
 
 bottom of the bladder gradually deepens so as to form a well or 
 pouch behind the prostate. In old subjects, more particularly if 
 the prostate be enlarged, this pouch becomes of considerable depth, 
 and renders micturition tedious. It sometimes happens that a 
 stone in the bladder cannot be felt; the reason of which may be 
 that the stone, lodged in such a pouch below the level of the 
 neck of the bladder, escapes the detection of the sound. Under 
 these circumstances, if the patient be placed on an inclined plane 
 with the pelvis higher than the shoulders, the stone falls out of 
 the pouch, and is easily recognisable. 
 
384 SIDE VIEW OF THE PELVIC VISCERA. 
 
 This tube, about eighteen inches long, conveys the 
 urine from the kidney to the bladder. In the dissection 
 of the abdomen we saw it behind the peritoneum, descending along 
 the psoas muscle, and crossing the division of the common iliac 
 arteries. Tracing it downwards, in the posterior false ligament of 
 the bladder, we find that it runs along the bladder, external to the 
 vas deferens, and enters it about an inch and a half behind the 
 prostate, and about two inches from its fellow of the opposite 
 side (fig. 82). It perforates the bladder very obliquely, so that 
 the aperture, being valvular, allows the urine to flow into, but not 
 out of the organ. The narrowest part of the ureter is at the 
 vesical orifice; here, therefore, a calculus is more likely to be 
 detained than at any other part of the canal. 
 
 This tube conveys the seminal fluid from the testicle 
 
 Vas deferens. . , ., ,. P ., ., T . , 
 
 into the prostatic part of the urethra. It ascends at 
 the back part of the spermatic cord through the inguinal canal 
 into the abdomen; then leaving the cord at the inner ring, it 
 curves downwards over the side of the bladder, gradually approach- 
 ing nearer the middle line. Before it reaches the prostate it 
 passes between the bladder and the ureter ; then, becoming very 
 tortuous, it runs internal to the vesicula seminalis, and is joined 
 by the duct of this vesicle. The common duct thus formed 
 (ductus communis ejaculatorius) terminates in the lower part of 
 the prostatic portion of the urethra (fig. 73, p. 361). In point of size 
 and hardness, the vas deferens has very much the feel of whipcord.* 
 These are situated, one on either side, between the 
 bladder and the rectum (fig. 82). Each is a tube, 
 but so convoluted that it looks like a little sacculated 
 bladder. When rolled up, the tube is about two and a half inches 
 long ; when unravelled, it is more than twice that length, and 
 about the size of a small writing quill. Several blind tubes, or 
 csecal prolongations, proceed from the main one, after the manner 
 
 * The description in the text presumes the bladder to be distended. But when 
 the bladder is empty the vas deferens runs down upon the bide of the pelvis. In this 
 course it may be seen, through the peritoneum, crossing 1, the external iliac vessels ; 
 2, the remains of the umbilical artery ; 3, the obturator artery and nerve ; 4, the ureter. 
 
SIDE VIEW OF THE PELVIC VISCEKA. 385 
 
 of a stag's born. The vesiculse seminales do not run parallel, but 
 diverge from each other posteriorly, like the branches of the letter 
 V ; and each lies immediately on the outer side of the vas deferens, 
 into which it leads. The function of the vesicula? seminales is to 
 serve as reservoirs for the semen. 
 
 They contain a brownish-coloured fluid, presumed to be in 
 some way accessory to the function of generation.* 
 
 The prostate gland is situated at the neck of the 
 gland. bladder, and surrounds the first part of the urethra 
 
 (p. 394). In the healthy adult it is about the size and 
 shape of a chesnut. Its apex is directed forwards. It is sur- 
 rounded by a plexus of veins (p. 379), and is maintained in its 
 position by the pelvic fascia (p. 378). Its upper surface is about 
 three-quarters of an inch below the symphysis pubis : its apex is 
 about one inch and a half from the anus ; the base is about two 
 and a half. 
 
 Above the prostate are the anterior ligaments of the bladder, 
 with the dorsal vein of the penis between them ; below, and in 
 contact with it, is the rectum ; on each side of it is the levator 
 ani ; in front of it we have the membranous part of the urethra 
 (surrounded by its compressor muscle), and the triangular liga- 
 ment; behind, are the neek of the bladder and the vesiculse 
 seminales with the ejaculatory ducts. 
 
 The transverse diameter is about one inch and a half; the 
 vertical is about half an inch less. But the gland varies in size 
 at different periods of life. In the child it is not developed, or at 
 all events is very small : it gradually grows towards puberty, and 
 generally increases in size with advancing age. 
 
 To ascertain the size and condition of the prostate during life, 
 the bladder should be at least half full : the prostate is then 
 pressed down towards the rectum, and more within reach of the 
 finger. 
 
 The urethra is a canal about eight inches in length, 
 
 Anatomy of 
 
 the urethra and leads from the bladder to the end of the penis. 
 
 * The vesiculse seminales are imperfectly dereloped till the age of puberty. In a 
 child of three years of age they can hardly be inflated with the blowpipe.. 
 
 C C 
 
386 SIDE VIEW OF THE PELVIC VISCERA. 
 
 in its passage ft is divided into three portions the prostatic, the 
 
 under the 
 
 pubic arch, membranous, and tiie spongy. At present we can only 
 
 examine the relations of the membranous part, which 
 comprises that part of the canal intermediate between the pros- 
 tate and the bulb. The urethra in this part is about one inch in 
 length, but somewhat longer on its upper than its lower surface, 
 in consequence of the encroachment of the bulb. In its passage 
 under the arch of the pubes, it is surrounded by the muscular 
 fibres of the compressor urethrse. It traverses the two layers of 
 the triangular ligament, and is about an inch below the symphysis 
 pubis, and nearly the same distance from the rectum ; it is not, 
 however, equidistant from this portion of the intestine at all points, 
 because of the downward bend which the rectum makes towards 
 the anus.* 
 
 The membranous part of the urethra in children is very long, 
 owing to the smallness of the prostate at that period of life ; it 
 is also composed of thin and delicate walls, and lies close to the 
 rectum. In sounding a child, therefore, it is very necessary not 
 to use violence, else the instrument is likely to pass through the 
 coats of the urethra and make a false passage. 
 
 This muscle supports the anus and lower part of the 
 
 rectum like a sling ; and, with the coccygeus and com- 
 pressor urethrse, forms a muscular floor for the cavity of the pelvis. 
 To see it, the pelvic fascia must be reflected from its inner sur- 
 face. It arises from the ramus of the pubes near the symphysis, 
 from the spine of the ischium, and from a tendinous line extend- 
 ing in a gentle curve between these points of bone ; this line being 
 the division of the pelvic fascia (p. 378). From this long origin 
 the fibres descend, and are inserted thus the anterior, passing 
 under the prostate, meet their fellow in the middle line of the 
 perineum in front of the anus (sometimes called levator pros- 
 tatse) ; the middle are inserted into the side of the rectum, while 
 the posterior meet their fellow behind the rectum. 
 
 * If a clean vertical section were made, we should see that the two canals form the 
 sides of a triangular space, of which the apex is towards the prostate. This is some- 
 times called the recto-urethral triangle. 
 
SIDE VIEW OF THE PELVIC VISCERA. 387 
 
 The function of the levatores ani is to retract the anus and the 
 rectum after it has been protruded in defsecation by the combined 
 action of the abdominal muscles and the diaphragm. 
 
 This muscle should be regarded as a continuation of 
 the levator ani. It arises from the spine of the 
 ischium, gradually spreads out, and is inserted into the side of 
 the coccyx, which it serves to support. 
 
 At this stage of the dissection, the bladder should be drawn 
 downwards, and the branches of the internal iliac artery and the 
 sacral plexus clearly displayed. 
 
 Fig. 84. 
 
 MOT 
 
 SAC LAT? 
 
 PLAN OF THE BRANCHES OF THE INTERNAL ILIAC. 
 
 Internal From the division of the common iliac artery, the 
 
 iliac artery internal iliac descends into the pelvis, and, after a 
 and branches. course o f a b ou t an inch and a half, divides, opposite 
 the great sacro-ischiatic notch, into two large branches, an ante- 
 rior and a posterior (fig. 84). The artery lies upon the lumbo- 
 sacral cord and the pyriformis muscle ; the ureter, inclosed in the 
 posterior false ligament of the bladder, passing in front. 
 
 The posterior division gives off the ilio-lumbar, lateral sacral, 
 and glutseal arteries ; the anterior gives off the superior vesical, 
 obturator, inferior vesical, middle hsemorrhoidal, ischiatic and 
 
 c c 2 
 
388 SIDE VIEW OF THE PELVIC VISCERA. 
 
 pudic ; also the uterine and vaginal in the female. Such is their 
 usual order; but these branches, though constant as to their 
 general distribution, vary as to their origin. 
 
 a. The ilio-lumbar is analogous to the lumbar branches of the 
 aorta. It ascends outwards beneath the psoas, sends branches to 
 this muscle and the quadratus lumborum; then, running near 
 the crest of the ilium, it supplies the iliacus internus, and finally 
 inosculates with the cicumflexa ilii (p. 354). 
 
 6. The lateral sacral, usually two in number, descend perpen- 
 dicularly in front of the sacral foramina, and inosculate on the 
 coccyx with the middle sacral artery. They give branches to the 
 pyriformis, the bladder, and rectum, and others which enter the 
 anterior sacral foramina for the supply of the camda equina. 
 
 c. The glutceal is the largest branch. It passes immediately out 
 of the pelvis through the great ischiatic notch, above the pyriformis 
 muscle, and then divides into branches for the supply of the great 
 muscles of the buttock. These will be dissected with the thigh. 
 
 d. The superior vesical artery comes off from the unobliterated 
 portion of the hypogastric, and supplies the upper part of the 
 bladder. It gives off the middle vesical artery ; and a still smaller 
 one, the deferential, which accompanies the vas deferens. The 
 inferior vesical artery ramifies on the under surface of the bladder, 
 the vesiculse seminales and the prostate, and gives off the middle 
 hsemorrhoidal which supplies the rectum. 
 
 e. The obturator artery runs along the side of the pelvis, below 
 the corresponding nerve, to the upper part of the obturator fora- 
 men, through which it passes to be distributed to the muscles of 
 the thigh. In the pelvis it gives off a small branch to the iliacus 
 internus, and another, the pubic, which ramifies on the back of 
 the pubes. 
 
 The obturator artery does not, in all subjects, take the course 
 above stated. It may arise from the external iliac near the crural 
 arch, or by a short trunk in common with the epigastric.* Under 
 
 * In most subjects a small branch of the obturator ascends behind the ramus of the 
 pubes to inosculate with the epigastric. The variety in which the obturator arises in 
 
SIDE VIEW OF THE PELVIC VISCERA. 389 
 
 these circumstances, in order to reach the obturator foramen, it 
 generally descends on the outer side of the femoral ring. Instances, 
 however, occasionally occur, where it makes a sweep round the 
 inner side of the ring ; so that three-fourths of the ring, or, what 
 comes to the same thing, of the mouth of a femoral hernia, would 
 in such a case be surrounded by a large artery.* 
 
 /. The ischiatic artery is smaller than the glutseal. It proceeds 
 over the pyriformis and the sacral plexus, to the lower border of 
 the great ischiatic notch, through which it passes out of the pelvis 
 to the buttock, where it runs with the great ischiatic nerve. It 
 gives off small muscular branches in the pelvis to the pyriformis 
 and coccygeus. 
 
 g. The pudic artery supplies the perineum and the penis. It 
 passes out of the pelvis through the great ischiatic notch, below 
 the pyriformis, crosses the spine of the ischium, and re-enters the 
 pelvis through the lesser notch. It then ascends on the inner side 
 of the obturator internus towards the pubic arch, where it gives 
 branches to the several parts of the penis. In its passage over the 
 obturator muscle it is inclosed in a strong tube of fascia (formed 
 by the obturator fascia), and is situated about one inch and a 
 quarter above the tuberosity of the ischium. The branches of the 
 pudic artery were described in the dissection of the perineum 
 (p. 374). 
 
 The pudic artery, however, sometimes takes a very different 
 course. Instead of passing out of the pelvis, it may run by the 
 side of the prostate gland to its destination ; or, one of the large 
 branches of the pudic may take this unusual course, while the 
 pudic itself is regular, but proportion ably small. All practical 
 anatomists are familiar with these varieties, and we seldom pass a 
 
 common with the epigastric is but an unusual development of this branch. The branch 
 derives additional interest from the fact, that after ligature of the external iliac it 
 becomes greatly enlarged, and carries blood directly into the epigastric. See a case in 
 Med. Chir. Trans, vol. xx. 1836. 
 
 * The Museum of St. Bartholomew's Hospital contains two examples of double 
 femoral hernia in the male, with the obturator arising on each side from the epigastric. 
 In three out of the four ruptures the obturator runs on the inner side of the mouth of 
 the sac. (See Preparations 55, 69, Series 17.) 
 
390 SIDE VIEW OF THE PELVIC VISCEKA. 
 
 winter session without meeting with one or two examples of them. 
 It need hardly be said that lithotomy, under such conditions, might 
 be followed by fatal haemorrhage. 
 
 h. The middle sacral artery is a very diminutive prolongation 
 of the aorta down to the coccyx. It becomes gradually smaller as 
 it descends, and finally inosculates with the lateral sacral arteries. 
 In animals this is the artery of the tail. 
 
 Eespecting the veins in the pelvis, they correspond with the 
 arteries, and empty themselves into the internal iliac vein. The 
 remarkable plexus of veins about the prostate, neck of the bladder, 
 and rectum, has been described (p. 379). 
 
 NERVES OF Those which proceed from the spinal cord should be 
 THE PELVIS, examined first, afterwards those derived from the sym- 
 pathetic system. 
 
 Sacral nerves Five sacral nerves proceed from the spinal cord 
 and plexus, through the sacral foramina. The upper four, from 
 their large size, at once attract observation ; but the fifth is small, 
 perforates the coccygeus muscle, supplying it and the skin over 
 the coccyx. 
 
 The coccygeal nerve is not easily found : it communicates with 
 the fifth sacral nerve, and supplies the same parts as that nerve ; 
 namely, the coccygeus and the skin over the coccyx. 
 
 The three upper sacral nerves, and part of the fourth, with the 
 lumbo-sacral cord, form the sacral plexus. The great nerves of 
 the plexus lie on the pyriformis muscle, beneath the branches of 
 the internal iliac artery, and coalesce to form the great ischiatic 
 nerve, which passes out at the back of the pelvis, for the supply 
 of the flexor muscles of the inferior extremity. The other branches 
 of the plexus are as follow : 
 
 a. Muscular branches distributed to the levator ani, the coccy- 
 geus, the cutaneous sphincter of the anus, the pyriformis, gemelli, 
 quadratus femoris, and obturator internus. The nerve to the last- 
 named muscle (sometimes derived from the pudic) leaves the 
 pelvis with the pudic artery, and re-enters with it to reach the 
 muscle. / 
 
 b. The superior glutceal nerve proceeds from the lumbo-sacral, 
 
SIDE VIEW OF THE PELVIC VISCERA. 
 
 391 
 
 leaves the pelvis above the pyriformis with the glutaeal artery, and 
 supplies the glutseus medius and minimus, and the tensor fasciae 
 femoris. 
 
 c. The lesser ischiatic supplies the glutseus maximus, the skin 
 of the buttock, the perineum, and the back of the thigh. 
 
 Fig. 85. 
 
 LUMB* 
 
 12. N. of pyriformis. 
 
 13. N. of geinellus superior. 
 
 14. N. of gemellus inferior. 
 
 15. N. of quadratus femoris. 
 
 16. N. of glutaeus maximus. 
 
 17. Long pudendal n. 
 
 18. Cutaneous n. of the but- 
 
 tock. 
 
 19. N. of the long head of 
 
 the biceps. 
 
 20. N. of semi-tendinosus. 
 
 21. N. of semi-membrano- 
 
 sus. 
 
 22. N. of short head of the 
 
 biceps. 
 
 1,2, 3, 4,' 5." Sacral nn. 
 
 6. Superior glutaeal n. 
 
 7. Great ischiatic n. 
 
 8. Lesser ischiatic n. 
 
 9. Pudic n. 
 
 10. N. of obturator interims. 
 
 11. N. of levator ani. 
 
 PLAN OF THE SACBAL PLEXUS AND BEANCHES. 
 
 d. The pudic nerve runs with the pudic artery, and like it, sup- 
 plies the rectum, the muscles of the perineum, and the penis. 
 
 e. The branches for the pelvic viscera are very small. They 
 proceed chiefly from the third and fourth sacral nerves, and form 
 an intricate plexus about the bladder, prostate, and rectum. 
 
 From the lumbar region the sympathetic nerve 
 
 Sympathetic ^ escen( j s j n t o the pelvis, along the inner side of the 
 
 sacral foramina. In this part of its course its ganglia 
 
392 STRUCTURE OP THE BLADDER AND PROSTATE. 
 
 vary in number from three to five. The nerves of opposite sides 
 unite in front of the coccyx, where they form the 'ganglion 
 import 
 
 The plan upon which the sympathetic nerves are distributed in 
 the pelvis is similar to that in the abdomen. Each ganglion re- 
 ceives one or two filaments from a spinal nerve, and then gives off 
 its branches to the viscera. The visceral branches are exceedingly 
 delicate, and cannot be traced unless the parts have been previ- 
 ously hardened in spirit. They accompany the arteries supplying 
 the respective organs, and are called the * vesical,' e prostatic,' and 
 s inferior haemorrhoidal plexuses ; ' and in the female the ' uterine ' 
 and ' vaginal.' 
 
 According to the accurate dissections of Miiller, the vesical 
 filaments of the sympathetic do not stop at the prostate, but pass 
 on beneath the pubic arch into the corpus cavernosum penis. 
 Thus the erectile tissue of the intromittent organ is brought 
 directly within the influence of the sympathetic system. 
 
 STRUCTURE OF THE BLADDER, PROSTATE, URETHRA, AND PENIS. 
 
 The parts are presumed to have been collectively taken out from 
 the pelvis, and the partial peritoneal covering of the bladder to 
 have been removed. 
 
 The bladder is composed of a partial peritoneal coat, 
 a muscu l ar 5 an ^ a mucous ; these latter are connected by 
 an intermediate layer of cellular tissue, out of which 
 anatomists make a fourth coat, and call it the cellular. 
 
 The serous or peritoneal coat invests the posterior, lateral, and 
 superior surfaces of the bladder; being absent on the anterior arid 
 inferior aspect 
 
 The muscular is situated beneath the serous, and cou Hints of 
 unstriped or involuntary muscular fibres, which interlace with 
 each other in all directions. Their general arrangement is as 
 follows : An outer, or longitudinal, layer arises from the upper 
 half of the circumference of the prostate and the neck of the 
 
STRUCTURE OF THE BLADDER AND PROSTATE. 393 
 
 bladder, and thence its fibres spread out longitudinally over the 
 summit of the bladder, pass round its posterior aspect and base, to 
 be inserted into the prostate in the male, and the vagina in the 
 female. This layer is especially marked on the anterior and 
 posterior surfaces of the bladder. Under this is a layer of circular 
 Jibres, especially developed near the neck. Towards the sides of 
 the bladder the two sets of fibres have a less definite arrangement, 
 and form a kind of network: these, therefore^ are the weakest 
 parts of the bladder, and more liable to the formation of pouches.* 
 The development and colour of the muscular fibres depend upon 
 whether the subject has suffered from irritation of the bladder, or 
 any obstruction to the expulsion of the urine. 
 
 The cellular coat serves to connect the muscular to the mucous, 
 and is composed of ordinary connective tissue. The mucous coat 
 is everywhere loosely connected to the muscular, except opposite 
 the ( trigonej where they adhere more firmly. 
 
 The bladder must be hud open by an incision alon^ its front 
 surface, to examine its interior. In a recently contracted bladder, 
 the mucous membrane is disposed in irregular folds, which dis- 
 appear when the bladder is distended. In a healthy state, it is 
 pale; when inflamed it becomes of a bright red. Under the 
 microscope, its surface is seen to be studded with follicles. These 
 follicles secrete the thick ropy mucus in inflammation of the 
 bladder. 
 
 The epithelium lining the mucous membrane varies in different 
 parts of the bladder. Part is squamous ; part consists of a variety 
 transitional between sqnamons and eohnnnar. 
 
 The orifice of the urethra is situated at the lower and anterior 
 part of the bladder, not at the most dependent part, which forms 
 
 * These pouches arise in the following manner : A portion of mucous membrane is 
 protruded through ouo of the muscular interstices, so as to form a little sac. This is 
 small at first, but gradually increases in size, because, having no muscular coat, it has 
 no power of emptying itself; generally speaking, several sueh sacs are met with in the 
 same bladder ; and they sometimes contain calculi. If a calculus, originally loose in 
 the bladder, happen to become lodged in a pouch by the side of it, a sudden remission 
 of the symptoms may i>n<ue. This explains our inability to detect its presence by a 
 sound. 
 
394 STRUCTURE OF THE BLADDER AND PROSTATE. 
 
 Fig. 86. 
 
 Ureter. 
 
 Prostate gland 
 
 Membranous part of 
 the urethra . . . 
 
 Orifice of ureter. 
 
 - Uvula. 
 
 Caput gallinaginis. 
 
 Orifice of seminal 
 duct. 
 
 Cowper's gland. 
 Bulb of urethra. 
 Crus penis. 
 
 Orifice of the duct of 
 Cowper's gland. 
 
 One of the lacunae. 
 Corpus cavernosum. 
 
 Glans penis. 
 
 BLADDKR AND URETHRA LAID OPEN BY AN INCISION ALONG ITS UPPER SURFACE. 
 
STRUCTURE OF THE BLADDER AND PROSTATE. 395 
 
 the well behind the orifice, in which urine is apt to accumulate in 
 old persons. It appears small and contracted in the fresh bladder, 
 but if the little finger be introduced into it, we find that it will 
 dilate to a very considerable size. Immediately behind the orifice 
 is observed in some bladders a slight elevation, called the ( uvula.' 
 It is composed of a portion of the mucous membrane raised up by 
 an accumulation of the submucous tissue, and is rarely of sufficient 
 size to interfere with the passage of the urine. This elevation 
 must be distinguished from enlargement of the third or middle 
 lobe of the prostate. 
 
 The orifices of the ureters are situated about an inch and a half 
 behind the urethra, and about two inches apart. These tubes 
 perforate the coats of the bladder obliquely, and slant towards 
 each other, standing out in relief under the mucous membrane.* 
 A little ridge proceeds from the orifice of each ureter down to the 
 neck of the bladder, looking like a continuation of the ureter 
 itself. If the mucous membrane be removed from these ridges, 
 we find that they are produced by muscular fibres. Sir Charles 
 Bell,t who first drew attention to them, believed them to be of 
 use in regulating the orifices of the ureters, and named them ' the 
 muscles of the ureters.' 
 
 The ridges, converging from the ureters, together with an im- 
 aginary horizontal line, drawn between their orifices, include a 
 smooth triangular area, called, by the French anatomists, the 
 ' trig one vesicated The mucous membrane of this area is more 
 firmly adherent to the subjacent tissue than in other parts of the 
 bladder, and is therefore perfectly smooth. It is more richly 
 
 * This slanting of the ureters serves all the uses of a valve. The urine enters the 
 bladder, drop by drop, but cannot return, because the internal coat is pressed against 
 the other side of the orifice, so as to stop it. When the bladder becomes thickened, 
 in consequence of difficulty in passing the water, it sometimes happens that the ureters 
 loose their valvular direction, so that the urine, when the bladder contracts, is partly 
 forced back up the ureters ; the result is, that they become dilated, and so does the 
 pelvis of the kidney. 
 
 f Med. Chir. Trans, vol. iii. He says, ' These muscles guard the orifices of the 
 ureters by preserving the obliquity of the passage, and pulling down the extremities of 
 the ureters according to the degree of the contraction of the bladder generally.' 
 
396 STRUCTURE OF THE PROSTATE. 
 
 provided with blood vessels and nerves than the rest of the 
 bladder, and is endowed with more acute sensibility. This is the 
 reason why a stone is more painful when the bladder is empty ; 
 and in the erect, than in the recumbent position. 
 
 The bladder is supplied with blood by the ' superior,' f middle,' 
 and ' inferior ' vesical arteries. The superior comes from the 
 unobliterated portion of the umbilical the middle from the 
 superior vesical or the internal iliac ; the inferior from the anterior 
 division of the internal iliac or the pudic. 
 
 The vesical plexus of veins terminates in the internal iliac vein.* 
 
 The nerves of the bladder are derived from the hypogastric and 
 sacral plexuses. 
 
 Having already examined the form, size, and rela- 
 tions of the prostate (p. 385), you have now to make 
 out its two lateral symmetrical lobes. There is, also, a third or 
 middle lobe.f It unites the lateral lobes, and is situated above the 
 seminal ducts. In health, this does not appear like a separate 
 lobe ; but when abnormally enlarged, it projects towards the cavity 
 of the bladder, and acts like a bar at the mouth of the urethra. 
 
 Make a longitudinal incision through the upper surface of the 
 prostate to expose the urethra. The canal does not run exactly in 
 the centre of the gland, but rather nearer to its upper surface ; 
 nor is it of the same calibre throughout. It forms a ( sinus ' in 
 the interior of the prostate, described by anatomists as the ( sinus of 
 the prostate.'' Along the floor of the sinus is a longitudinal ridge, 
 about three quarters of an inch in length, broad and elevated 
 behind, but gradually lost forwards in a narrow point. This is 
 
 * The attention of the student should be directed to the very admirable injections 
 of the veins of the bladder by Pettigrew, in the Museum of the Eoyal College of 
 Surgeons. 
 
 t Attention was first attracted to this middle lobe, in England, by Sir Everard 
 Home, whose account of it is published in the Philos. Trans, for 1806. The prepara- 
 tion prepared by Sir Everard in illustration is preserved in the Museum of the Eoyal 
 College of Surgeons in London, Physiol. Series, No. 2583 A. But the anatomy and 
 effect of the enlargement of this part of the prostate gland is not a discovery of modern 
 times. It was accurately described by Santorini in 1739, and subsequently by Camper, 
 and is alluded to by Morgagni in the third book of his Epistles. 
 
STRUCTURE OF THE PROSTATE. 397 
 
 called the crest of the urethra, and the most prominent part of it 
 is named the ' veru montanum,' or f caput gallinaginis,' from its 
 supposed resemblance to the head of a woodcock. The seminal 
 ducts open close to each other, one on either side of this promi- 
 nence (p. 394). 
 
 Immediately in front of the caput gallinaginis, precisely in the 
 middle line, is a small opening which will admit a probe. It 
 leads backwards into a little ' cul-de-sac ' or pouch in the sub- 
 stance of the prostate. This pouch is described as the analogue of 
 the uterus, and called the ' utriculus ' or ' sinus pocularis.' It is 
 of a pyriform shape, with the narrowest part at the orifice, and its 
 length is about five or six lines. Practically it deserves attention, 
 because in some persons it is large enough to catch the end of a 
 small catheter. The minute orifices of the proper ducts of the 
 prostate, from fifteen to twenty in number, are seen opening into 
 the floor of the prostatic sinus.* The whole substance of the gland 
 is permeated by the divisions and subdivisions of the ducts. They 
 are not visible to the naked eye, but if traced out with the micro- 
 scope, they are seen to terminate in blind sacculated extremities, 
 upon which the capillaries ramify in rich profusion. f 
 
 Modern observations prove that the prostate is more of a muscular 
 than a glandular body. Nearly two-thirds of it is made up of 
 muscular fibre of the non-striped variety. The great mass of this 
 muscular fibre is arranged in a circular manner round the urethra, 
 so as to form a sphincter. The prostate is remarkable for its 
 dilatability. If a small incision be made through the anterior part 
 of the gland, the base being left entire, the gland may be dilated 
 
 * In the ducts of the prostate we often find small calculi, of a brown colour, con- 
 sisting of phosphate of lime. Cases are sometimes met with in which these calculi by 
 degrees attain a consi 'erable size, and distend the prostate into a kind of sac, which 
 when examined by the rectum feels not unlike a bag of marbles. 
 
 f This was first demonstrated by Mr. Quekett. The same distinguished anatomist 
 has also discovered that the secreting cells of the gland contain calculi of microscopic 
 minuteness. He finds them, almost without exception, in the prostate at every period 
 of life. For further detail concerning them consult the article 'Prostate' in Todd's 
 Cyclopaedia. 
 
398 STRUCTURE OF THE PROSTATE. 
 
 by the finger sufficiently to admit the extraction of even large 
 calculi. 
 
 Any change in the dimensions of the prostate must affect the 
 canal which runs through it, and more or less obstruct the flow of 
 urine. If the entire gland be uniformly enlarged, the length of 
 the prostatic urethra will be increased ; if the enlargement pre- 
 ponderate at one part more than another, then the canal will 
 deviate more or less from its natural track and assume a more 
 angular or a lateral curve according to the part enlarged. When 
 the middle lobe becomes enlarged, there arises, at the neck of the 
 bladder, a growth, which will, in proportion to its size, more or less 
 obstruct the passage of the urine. In the efforts made to intro- 
 duce a catheter into the bladder, it sometimes happens that the 
 end of the instrument is pushed through this hypertrophied lobe.* 
 The external appearance of these bodies has been 
 v ? 8JfU already described (p. 384). Eespecting their structure, 
 we find that they have an external coat derived from 
 the pelvic fascia ; a middle or fibrous, strong and somewhat elastic, 
 and an internal or mucous. The mucous membrane is lined by a 
 scaly epithelium, and presents a beautiful honey-comb structure, not 
 unlike that of the gall-bladder : the purpose of this is to increase 
 the extent of the secreting surface. According to some anatomists, 
 muscular fibres are present in the fibrous investment of the vesiculse 
 seminales, for the purpose of expelling their contents. The duct 
 emerges from the anterior part of the vesicula, and joins at an 
 acute angle the vas deferens behind the prostate, to form the 
 common ejaculatory duct (p. 361). The function of these bodies 
 is twofold : they act as reservoirs for the semen, and secrete a fluid 
 accessory to generation. 
 
 The glands, of Cowper have been examined in situ in 
 
 glands! S the dissection of the perineum (p. 374). We find them 
 
 close to the urethra, one on either side, immediately 
 
 behind the bulb and between the two layers of the triangular 
 
 ligament. They consist of an aggregation of smaller glands, of 
 
 * See the Museum of St. Bartholomew's, Prep. 8 and 21, Series xxix. 
 
URETHRA. 399 
 
 which the collective size is somewhat larger than a pea. Each 
 pours its secretion by a single and very minute duct about one 
 inch long into the bulbous part of the urethra. The use of these 
 glands appears to be like that of the vesiculse seminales and the 
 prostate ; namely, to pour into the urethra a fluid accessory in some 
 way to generation. They are found in all mammalia, and in some, 
 e.g. the mole, they increase in size periodically with the testicle. 
 
 Urethra ure ^ nra * s the tube which leads from the bladder 
 
 to the end of the penis, and serves not only as the ex- 
 cretory duet of the bladder, but transmits the secretion of the 
 testicles and the several glands accessory to generation. It is 
 surrounded by different structures in different parts of its course. 
 The first inch, or thereabouts, is surrounded by the prostate gland 
 (p. 361); the second inch, which passes under the pubic arch, is 
 surrounded by the compressor urethras (p. 372) ; the remainder of 
 its course along the penis is surrounded by erectile tissue, termed 
 ' corpus spongiosum.' Hence it is divided into the prostatic, the 
 muscular or membranous, and the spongy. The length of the 
 whole is about seven or eight inches, but this varies according to 
 the condition of the penis. 
 
 The direction of the urethra, when the penis hangs flaccid, is 
 like the letter S reversed ; but if the penis be held straight, the 
 canal forms only one curve through the pubic arch, with the con- 
 cavity upwards. The degree of this curvature varies at different 
 periods of life. In the child, the bladder being more in the 
 abdomen than in the pelvis, the curve forms part of a much smaller 
 circle than in the adult ; but it gradually widens as age increases, 
 and catheters are shaped accordingly.* However, the parts, when 
 in a sound state, will yield sufficiently to admit the introduction of 
 a straight instrument into the bladder. Aston Key always used a 
 straight staff in lithotomy. 
 
 In its contracted state, the sides of the urethra are in close appo- 
 
 * The sharper curve of the urethra in the child was well known to Camper. ' In 
 recenter natis, vesica basi sua elatius sita, pedetentim descendit, unde necessario se- 
 quitur curvaturam urethrse majorem esse in junioribus quam in adultis.' Demon, 
 Anat. Pathol. lib. ii. p. 13. 
 
400 URETHRA. 
 
 sition ; the appearance it presents on a transverse section differs in 
 the different parts of its course. Through the glans it is flattened 
 vertically, its two sides being in contact ; through the prostate, also, 
 it is nearly flat, except at the lower part, where its sides are kept 
 asunder by the verumontanum, which projects upwards, fitting accu- 
 rately between them.* But throughout the rest of its course the 
 lining membrane is disposed in longitudinal folds, which project 
 into and accurately close the canal, precisely on the same plan as 
 that by which nature closes the oesophagus (p. 124). These longi- 
 tudinal folds are plainly seen even when the urethra is slit open ; 
 indeed, they do not disappear unless the canal be forcibly stretched 
 contrary to their direction.! 
 
 The urethra must be laid open from end to end, to see that the 
 canal is not of uniform calibre throughout. The external orifice 
 is the narrowest, and the least dilatable part ; so that the urine 
 may be expelled in a jet. Therefore, any instrument which will 
 enter the meatus ought to pass into the bladder, if there be no 
 stricture. The junction of the membranous with the bulbous part 
 is almost as narrow. The centre of the prostatic and the bulbous 
 parts are the largest. In the centre of the glans penis, the canal 
 widens into a little sinus, termed ( fossa navicularisS 
 
 The most dilatable part of the urethra is the prostatic. Even 
 the narrowest parts of the canal must admit of considerable dila- 
 tation, since calculi of from 3 to 4 lines in diameter have been 
 known to pass through it. 
 
 The seminal ducts open into the prostatic part of the urethra, 
 by the side of the verumontanum. The ducts of Cowper's glands 
 open into the bulbous part. Besides these glands, a number of 
 ducts open into the urethra, proceeding from little glands situated 
 in the sub mucous tissue. These ducts, called ' lacunae J are large 
 enough to admit a bristle, and run in the same direction as the 
 
 * See the transverse sections made by Pettigrew through the prostatic part of the 
 urethra in the Museum of the Koyal College of Surgeons. 
 
 f In a well-injected urethra we observe that the ridges of the folds possess very few 
 blood vessels, while the furrows between them are exceedingly vascular. For the de- 
 monstration of this fact the author is indebted to Mr. Quekett. 
 
ANATOMY OF THE PENIS. 401 
 
 stream of the urine. Most of them are on the lower surface of 
 the urethra; but one called 'lacuna magna' is on the upper sur- 
 face about 1J inch down the canal. 
 
 The mucous membrane of the urethra is laid upon a substratum 
 of areolar tissue. Then comes a thin layer of elastic fibrous tissue, 
 of which the fibres are arranged in a longitudinal and a transverse 
 direction giving the parts that springiness of which we are 
 sensible in introducing the catheter. Outside this is a layer of 
 muscular fibre. It has been demonstrated that the urethra is 
 surrounded throughout its whole course by muscular fibres of the 
 involuntary kind. Therefore, the whole of the canal having a 
 muscular coat, similar to an intestine, any part of it is liable to 
 spasmodic contraction. 
 
 The urethra is lined by spheroidal epithelium, and near the glans is 
 provided with papillae : this, therefore, is the most sensitive part. 
 
 Lastly, the urethra is provided with a closely-set network of 
 absorbent vessels, a fact which has been demonstrated by the 
 beautiful quicksilver injections of Panizza.* They run from 
 behind, forwards, and join the absorbents of the glans penis. 
 Eventually, their contents are transmitted down the great trunks 
 on the dorsuin penis to the inguinal glands. This explains the 
 pathology of a bubo. 
 
 The skin of the penis is remarkably thin and ex- 
 f tensible, and connected to the body of the organ by 
 loose cellular tissue, destitute of fat. At the extremity, 
 the skin forms the prepuce, or foreskin, for the protection of the 
 glans ; f and the thin fold which passes from the under surface of 
 
 * Osservazioni antropo-zootom. &c., Pavia, 1830. This anatomist has also displayed 
 by injections an extremely fine network of absorbents which cover the glans penis. 
 The interstices of this network are smaller than the diameter of the tubes. 
 
 f When the foreskin is, from birth, so tight that the glans cannot be uncovered, such 
 a state is called a ' congenital phimosis.' This condition occasions no inconvenience in 
 childhood, but is apt, after puberty, to become troublesome and painful, so that it may 
 become necessary to slit up the prepuce and set the glans at liberty. In persons who 
 have a tight foreskin, it sometimes happens that, when the glans has been uncovered, 
 the prepuce cannot be again drawn over it : this is called a ' paraphymosis.' The neck 
 of the glans becomes tightly girt ; great distention and inflammation are the conse- 
 quences, and serious results may ensue, unless the foreskin be reduced. 
 
 I) D 
 
402 ANATOMY OF THE PENIS. 
 
 the glans to the prepuce is called ( frenum preputiiS The skin 
 is reflected over the glans, to which it adheres closely, and at the 
 orifice of the urethra is continuous with the mucous membrane. 
 
 The surface of the glans is covered, like the end of the finger, 
 by minute papillae, which are endowed with keen sensibility by 
 the dorsal nerves of the penis. Round its margin termed the 
 * corona glandis ' are a number of minute sebaceous glands, 
 which secrete a substance called 'smegma preputii.' 
 
 The bulk of the penis consists of two cylindrical bodies, of 
 erectile structure, named from the appearance of their interior 
 ' corpora cavernosa.' In a groove along their under surface runs 
 the urethra, which is itself surrounded by a vascular spongy tissue 
 called c corpus spongiosum : ' an expansion of this at the end of 
 the organ forms the glans. These structures, then the corpora 
 cavernosa and the corpus spongiosum together form the penis; 
 though the corpus spongiosum appears closely united to the 
 corpora cavernosa, yet it is quite distinct from them, as shown in 
 the transverse section (p. 403). 
 
 The corpora cavernosa constitute more than two-thirds of the 
 bulk of the penis. Each commences posteriorly by a gradually 
 tapering portion, called the ' crus penis,' which is attached along 
 a groove in the rami of the ischium and pubes. The crura 
 -converge, come into apposition at the root of the penis, and then 
 run on, side by side, to form the body of the organ. Anteriorly, 
 each terminates in a rounded end, received into a corresponding 
 depression in the glans, which fits on like a cap. 
 
 The upper part of the penis is connected to the symphysis ptibis 
 by an elastic triangular ligament, called ' ligamentum suspensorium 
 penis.' 
 
 In a longitudinal section through the corpus cavernosum, we 
 observe that its interior is composed of a delicate reticular 
 structure, surrounded by a thick fibrous coat. This coat is from 
 half a line to a line in thickness, and is composed of white fibrous 
 tissue intermingled with yellow elastic fibres. It forms a cylinder 
 of adequate strength to support the delicate structure within, and 
 sufficiently elastic to allow the distention of the penis. This coat, 
 
ANATOMY OF THE PENIS. 403 
 
 also, forms a median vertical partition between the two corpora 
 cavernosa. 
 
 The partition is only complete near the root of the penis ; along 
 the rest of the organ there are gaps in it, giving it the appearance 
 of a comb ; hence its name ( septum pectiniforme. 9 Through this 
 partition the blood vessels on one side communicate freely with 
 those on the other. 
 
 Fig. 87. 
 
 5 A 3 4 5 
 
 3. Vena dorsalis. W 5 ' 5 ' Dor8al nerV6S ' 
 
 TRANSVERSE SECTION THROUGH THE PENIS. 
 
 The interior of each cylinder is occupied by a number of delicate 
 elastic fibrous septa ( ( trabeculi '), which intersect each other in all 
 directions, and form a multitude of minute cells. These com- 
 municate freely with each other, as may be readily ascertained by 
 blowing air into the penis. They are not of equal size throughout 
 the penis ; they are smaller, and their component septa thicker at 
 the circumference than in the centre of the corpora cavernosa ; at 
 the root, than towards the glans. All the cells communicate 
 freely with the arteries. When the penis is flaccid, they are 
 empty ; when it is erect, they are distended with blood. 
 
 The arteries of the corpora cavernosa come from the pudic, 
 enter the inner side of each crus, and proceed forwards near the 
 septum, distributing numerous ramifications. These are supported 
 in the middle of the fibrous septa, and end, some in capillaries 
 which discharge their blood at once into the cells, others in 
 tendril-like prolongations with dilated extremities which project 
 into the cavities of the veins. These arteries (called ( helicine ' 
 by Miiller) are absent near the glans, and are best marked at the 
 root of the penis. 
 
404 ANATOMY OF THE PENIS. 
 
 The blood from the cells of the penis returns partly through 
 veins which pass out on the upper surface of the penis into the 
 great dorsal vein, which joins the prostatic plexus; partly through 
 the deep veins which leave the inner side of each crus, and the 
 bulb, to join the internal iliac. 
 
 The corpus spongiosum is the erectile tissue which 
 Corpus spon- g urroun( j s the urethra as it runs along the penis. It 
 
 giosum. L 
 
 commences in the middle of the perineum, in a bulb- 
 like form, and at the end of the penis it expands to form the 
 glans. This is proved by the fact, that if the spongy body be 
 injected, the glans is filled also ; not so, if we inject the cavernous 
 body. The urethra does not pass exactly through the middle of 
 the spongy body, but runs nearer to its upper surface. The bulb 
 hangs more or less pendulous from the urethra (p. 361). In old 
 persons it extends lower down than in children, and is, conse- 
 quently, more exposed to injury in lithotomy. 
 
 The corpus spongiosum has a much thinner external coat than 
 the corpus cavernosum, but resembles it very much in its internal 
 appearance. The reticular structure, however, is somewhat finer 
 and more delicate. Its interior is composed of a plexus of minute 
 tortuous veins. This is easily demonstrated by injecting the dorsal 
 vein of the penis with wax. In this way we not only fill the spongy 
 body, but also the glans and the large veins which form the plexus 
 round the corona glandis.* 
 
 The chief nerves of the penis are the pudic. The largest branches 
 run along the dorsum to the outside of the glans : a few only enter 
 the erectile tissue of the organ. This, it has already been men- 
 tioned (p. 392), is supplied by filaments of the sympathetic nerve 
 proceeding from the hypogastric plexus. 
 
 The absorbent vessels proceeding from the glans and the integ- 
 ument of the penis join the inguinal glands. The absorbents of the 
 glans communicate freely all round it : this explains why a venereal 
 sore on one side, sometimes affects the inguinal glands on the other. 
 
 * In the Museum of the Eoyal College of Surgeons there is a beautiful preparation 
 in which the glans penis is injected with quicksilver, clearly showing it to consist of a 
 plexus of veins. Physiol. Series, No. 2588 A. 
 
FEMALE PERINEUM. 405 
 
 THE DISSECTION OF THE FEMALE PEEINEUM. 
 
 The pudenda in the female consist of folds of the integu- 
 ment, called the labia. Between these is a longitudinal fissure 
 which leads to the orifices of the urinary and genital canals. 
 
 The pubic region is generally covered by an accumu- 
 majora lation of fat, called ' mons Veneris.' From this, two 
 
 thick folds of skin descend, one on either side, consti- 
 tuting the ' labia majora.' Their junction, about one inch above 
 the anus, is called the commissure, or ( frenulum labiorum: ' it is 
 generally torn in the first labour. The inner layer of the skin of 
 the labium is thinner, softer, and more like mucous membrane 
 than the outer : for this reason, whenever matter forms in the 
 labium, the abscess bursts on the inner side. Where the labia are 
 in contact, they are provided with small sebaceous glands, of which 
 the minute ducts are observable on the surface. These glands 
 sometimes inflame and secrete an acrid matter which creates great 
 irritation and pruritus of the mucous surface of the vulva, often 
 difficult to allay. 
 
 By separating the external labia, two small and thin 
 minora. folds of integument are exposed, one on either side, 
 termed ' labia minora,' or, by the old anatomists, 
 ' nymphce.' These folds converge anteriorly, and form a hood for 
 the clitoris, called 'preputium ditoridis ; ' posteriorly they are 
 gradually lost on the inside of the labia majora. They never 
 contain fat, like the labia inajora, but are composed of a minute 
 plexus of veins. Between the nymphaB and about the clitoris, are 
 a number of sebaceous glands. 
 
 Between the labia minora, and below the clitoris, is an angular 
 depression called the 'vestibule,' at the back of which is the orifice 
 of the urethra, or c meatus urinarius.' Immediately below this is 
 the vagina, of which the orifice is partially closed in the virgin by a 
 thin fold of mucous membrane called the ' hymen.' 
 
 In form and structure the clitoris resembles the 
 penis on a very diminutive scale ; but there is no 
 
408 FEMALE PERINEUM. 
 
 corpus spongiosum, or urethra. Like the penis, it is attached to 
 the sides of the pubic arch by two crura (fig. 88, p. 407), each of 
 which is grasped by its special erector clitoridis. The crura unite 
 to form the body of the organ, which is tipped by a small glans. 
 The glans is provided with extremely sensitive papillse, and covered 
 by a little prepuce. Its dorsal arteries and nerves are exceedingly 
 large in proportion to its size, and have precisely the same course 
 and distribution as in the penis. Its internal structure consists of 
 a plexus of blood vessels, which freely communicate with those of 
 the labia minora, for one cannot be injected without the other. 
 
 A smooth channel called the vestibule, three-quarters 
 of an inch in length, leads from the clitoris down to the 
 orifice of the urethra. This orifice is not a perpendicular fissure 
 like that of the penis, but rounded and puckered, and during life 
 it has a peculiar dimple-like feel, which assists us in finding it 
 when we pass a catheter. You should practice the introduction of 
 the catheter in the dead subject, for the operation is not so easy as 
 might at first be imagined, provided the parts are not exposed. 
 The point of the fore-finger of the left hand should be placed at 
 the entrance of the vagina, and the meatus felt for ; when the 
 catheter, guided by the finger, slips, after a little manoeuvring, 
 into the urethra. The canal is about one inch and a half in length, 
 and runs along the upper wall of the vagina (p. 410). The two 
 canals adhere so closely together that you can feel the urethra 
 through the vagina like a thick cord. The urethra is slightly 
 curved with the concavity upwards ; but for all practical purposes 
 it may be considered straight. Its direction, however, is not hori- 
 zontal. In the unimpregnated state of the parts it runs nearly in 
 the direction of the axis of the outlet of the pelvis ; so that a probe 
 pushed on in the course of the urethra would strike against the 
 promontory of the sacrum. But after impregnation, when the 
 uterus begins to rise out of the pelvis, the bladder is more 
 or less raised also in consequence of their mutual connection ; 
 therefore the urethra, in the latter months of utero-gestation, ac- 
 quires a much more perpendicular course. 
 
 The female urethra is provided with a ( compressor' muscle, 
 
FEMALE PERINEUM. 407 
 
 essentially similar, in origin and arrangement, to that which 
 surrounds the membranous part of the urethra in the male. It 
 also passes through the triangular ligament (fig. 89, p. 410). 
 Though the prostate gland is wanting, yet there are minute 
 glands scattered all round it, especially near the neck of the 
 bladder. In consequence of the wider span of the pubic arch, and 
 the more yielding nature of the surrounding structures, the female 
 urethra is much more dilatable than the male. By means of a 
 sponge tent, it may be safely dilated to admit the easy passage of 
 the fore-finger into the bladder. Advantage is taken of this great 
 dilatability in the extraction of calculi from the bladder. 
 
 The mucous coat of the urethra is arranged in longitudinal folds, 
 
 Fig. 88. 
 
 1. Meatus urinarius. / id^^&T^k \ 3. Bulb of vagina. 
 
 2. Vagina. fa fjijm^\ \ 4. Clitoris with its two crura. 
 
 BULB OF THE VAGINA, 
 
 and is lined by squamous epithelium, which changes to the sphe- 
 roidal variety near the bladder. Next to the mucous coat is a 
 layer of elastic and non-striped muscular fibres intermixed. Out- 
 side all is a plexus of veins bearing a strong resemblance to 
 erectile tissue. 
 
 The vagina is the canal which leads to the uterus ; 
 at present, only the orifice of it can be seen. It is 
 surrounded by a sphincter muscle, easily displayed by removing 
 the integument. The muscle is about three-fourths of an inch 
 broad, and connected with the cutaneous sphincter of the anus in 
 such a manner that they together form something like the figure 8. 
 On each side of the orifice of the vagina, between the 
 mucous membrane and the sphincter, is a plexus of 
 tortuous veins, termed the bulb of the vagina, from its 
 
408 FEMALE PERINEUM. 
 
 analogy to the bulb of the urethra in the male. This vaginal bulb 
 extends across the middle line between the meat us urinarius and 
 the clitoris, as shown in fig. 88, which was taken from an injected 
 preparation in the Musee Orfila at Paris. 
 
 The hymen is a thin fold of mucous membrane which, 
 in the virgin, extends across the lower part of the en- 
 trance of the vagina, about half an inch behind the fourchette. 
 In most instances its form is crescent-shaped, with the concavity 
 upwards. There are several varieties of hymen ; sometimes there 
 are two folds, one on either side, so as to make the entrance of the 
 vagina a mere vertical fissure ; * or there may be a septum perfo- 
 rated by several openings (Hymen cribriformis), or by one only 
 (Hymen circularis). Again, there may be no opening at all in it, 
 and then it is called Hymen imperforatus. Under this last 
 condition no inconvenience arises till puberty. The menstrual 
 discharge must then necessarily accumulate in the vagina : indeed, 
 the uterus itself may become distended by it to such an extent as 
 even to simulate pregnancy.f 
 
 The presence of the hymen is not necessarily a proof of 
 virginity, nor does its absence imply the loss of it. Cases are 
 related by writers on midwifery in which a division of the hymen 
 was requisite to facilitate parturition. In MeckePs Museum, at 
 Halle, are preserved the external organs of a female in whom the 
 hymen is perfect even after the birth of a seven-months' child. 
 Bartholin's or ^ *^ e l wer P ar t f the orifice of the vagina is 
 Duverney's imbedded, in the loose tissue on either side, a small 
 gland,| which corresponds to Cowper's gland in the 
 male. Each has a long slender duct, which runs forwards and 
 opens on the inner side of the nympha. In cases of virulent 
 gonorrhoea these glands are apt to become diseased, and give rise 
 to the formation of an abscess in the labium, very difficult to 
 heal. 
 
 The description of the perineal branches of the pudic vessels 
 
 * Such an one may be seen in the Museum of the College, Phys. Series, No. 2843. 
 
 f See Burns' Midwifery. 
 
 | See Tiedemann, Von den Duverneysehen Driisen des Weibs. Heidelberg, 1840. 
 
CONTENTS OF FEMALE PELVIS. 409 
 
 and nerves, given in the dissection of the male perineum, applies, 
 mutatis mutandis, to the female, excepting that they are propor- 
 tionally small, and that the artery which supplies the bulb of the 
 urethra in the male is distributed to the bulb of the vagina in the 
 female. 
 
 DISSECTION OF THE FEMALE PELVIS. 
 
 The internal organs of generation, viz., the vagina, uterus, and 
 its appendages, should now be examined. 
 
 Their relative position should first be noticed ; and afterwards, 
 their special anatomy. 
 
 General The uterus is interposed between the bladder in 
 
 position of front, and the rectum behind. From each side of it a 
 and its broad fold of peritoneum extends transversely to the 
 
 appendages. s [^ e o f the pelvis, dividing that cavity into an anterior 
 and a posterior part. These folds are called the broad ligaments of 
 the uterus (fig. 90, p. 419). On the posterior surface of the ligament 
 are the ovaries, one on each side. They are completely covered by 
 peritoneum, and suspended to the ligament by a small peritoneal 
 fold. Each ovary is attached to the uterus by a round cord 
 termed the ' ligament of the ovary.' Along the upper part of the 
 broad ligament we find between its layers a tube about four inches 
 long, called the Fallopian tube, which conveys the ovum from the 
 ovary into the uterus. For this purpose, one end of it terminates 
 in the uterus, while that nearer to the ovary expands into a wide 
 mouth, furnished with prehensile fringes 'fimbrice ' which, like 
 so many fingers, grasp the ovum as soon as it is ready to escape 
 from the ovary. One of these fimbrise is attached to the ovary 
 Lastly, there run up to the ovary, between the layers of the broad 
 ligament, the ovarian vessels and nerves, which arise from the 
 aorta in the lumbar region, like the spermatic arteries in the 
 male, because the ovaries are originally formed in the loins. 
 
 On the anterior surface of the broad ligament, you see, on either 
 side between its layers, the round ligament of the uterus. This 
 
410 
 
 CONTENTS OF FEMALE PELVIS. 
 
 cord proceeds from the fundus of the uterus, anterior to the 
 Fallopian tube, through the inguinal canal, like the spermatic 
 cord in the male, and terminates in the ' rnons Veneris.' Besides 
 one or two small blood vessels, it contains muscular fibres ana- 
 logous to those of the uterus : these increase very much in 
 pregnancy, so that, about the full term, the cord becomes nearly 
 as thick as the end of the little finger. 
 
 Side view of After the removal of the innominate bone, as de- 
 the female scribed at p. 376, the vagina, rectum, and bladder 
 should be moderately distended, and a catheter passed 
 
 Fig. 89. 
 
 pelvis. 
 
 Urethra surround- 
 ed by its compres- 
 sor muscle . . . 
 
 Vagina 
 
 Rectum .... 
 
 Peritoneum in 
 doited outline. 
 
 Uterus. 
 
 VERTICAL SECTION THROUGH THE FEMALE PELVIS. 
 
 into the urethra. This done, the reflections of the peritoneum 
 must be traced. 
 
 Reflections From the front of the rectum the peritoneum is 
 
 of the peri- reflected on to a small part of the vagina, thus forming 
 
 what is called the 'recto-vaginal pouch.' From the 
 
 vagina we trace the peritoneum over all the back, but only about 
 
CONTENTS OF FEMALE PELVIS. 411 
 
 half way down the front of the uterus ; thence it is at once re- 
 flected over the posterior surface of the bladder, on to the wall of 
 the abdomen. Laterally it is reflected from the uterus to the 
 sides of the pelvis, forming the broad ligaments (p. 419). 
 
 In cases of ascites the fluid might distend the recto-vaginal 
 pouch, and bulge into the vagina, so that it would be practicable, 
 in some cases, to draw it off through this channel.* 
 
 *To the description of the fascia already given in the 
 dissection of the male pelvis (p. 378), nothing need be 
 added except that from the side of the pelvis it is reflected over 
 the side of the vagina and the uterus as well as the bladder. 
 
 It is this fascia which in great measure supports and braces up 
 the uterus in its proper level in the pelvis. When, from any 
 cause, the fascia becomes relaxed, there is a liability to ( prolapsus 
 uteri.' 
 Levator ani. For the description of this muscle see p. 386. 
 
 The female bladder is broader transversely, and, upon 
 the whole, more capacious than the male. The vesical 
 plexus of veins is not so large, and there are no vasa deferentia or 
 prostate gland. The short urethra has a constrictor muscle, as in 
 the male, and is supported in a similar manner by the pelvic 
 fascia. 
 
 Though the veins round the neck of the bladder are 
 
 Venous 
 
 plexus about comparatively small in the female, attention should be 
 the vagma. di rec t e d to the plexus of large veins which surround 
 the vagina and the rectum. They communicate in front with the 
 vesical plexus, and behind with the haemorrhoidal. Their con- 
 gestion in pregnancy sufficiently accounts for the dark colour of 
 the vagina and the external organs, and the frequent occurrence 
 of haBmorrhoidal turn ours. f These veins must be removed, with 
 
 * In the Medical Communications, vol. i., a case is related in which four gallons of 
 fluid were drawn off by tapping through the vagina. The woman immediately after- 
 wards passed \irine, which she could not do before. See also a case in Med. and Phys. 
 Journal, vol. vii. p. 412. 
 
 f* During pregnancy, varicose tumours may form even in the vagina. In the Berlin 
 Med. Zeitung, 1840, No. 11, a case is related of a woman who, at the sixtli month, 
 bled to death from the bursting of a large vein in the vagina. Other cases of the kind 
 are related by Siebold. 
 
412 CONTENTS OF FEMALE PELVIS. 
 
 the cellular tissue in which they are imbedded, before a clear view 
 of the parts can be obtained. 
 
 The urethra has already been described (p. 406). But 
 in the side view of the parts, we have the opportunity of 
 observing how closely the bladder and urethra are connected to the 
 upper wall of the vagina ; and we can understand how, in cases of 
 protracted delivery, it sometimes happens that the contiguous coats 
 of the bladder and the vagina give way, and that there remains 
 a fistulous communication between them, which continues to be 
 a depending drain for the urine. 
 
 It is necessary to slit open the whole of the vagina 
 along the side, to obtain a clear idea of the manner in 
 which it embraces the lower end of the uterus, and of the extent to 
 which the neck of the uterus projects into it. 
 
 The length of the vagina, in the unimpregnated adult, is, on an 
 average, about 4^ inches. It may be more, or less ; the difference 
 in each case depending upon the depth of the pelvis, the stature 
 and age of the individual. Owing to the curved direction of the 
 vagina, the anterior wall is about an inch shorter than the posterior. 
 The vagina, however, is never so long, that we cannot, during life, 
 feel the neck of the uterus projecting at the top of it; higher up, 
 or lower down, according to circumstances. For instance, it is a 
 little lower down in the erect than in the recumbent position ; again, 
 in the early months of utero-gestation, the uterus descends a little 
 into the vagina, so that this canal becomes shorter : the reverse 
 holds good when the uterus begins to rise out of the pelvis. 
 
 The axis of the vagina is slightly curved with the concavity up- 
 wards ; it corresponds with the axis of the outlet of the pelvis ; 
 whereas, the axis of the uterus corresponds with that of the cavity 
 of the pelvis. 
 
 The width of the vagina is not uniform throughout. The narrow- 
 est part is at the orifice ; it is also a little constricted round the 
 neck of the uterus. The widest part is about the middle : here a 
 transverse section through it presents the appearance of a broad 
 horizontal fissure. If therefore you would insert the bivalve spec- 
 ulum with the least amount of pain, the blades of the speculum 
 
CONTENTS OF FEMALE PELVIS. 413 
 
 should be vertical when introduced into the orifice of the vagina, 
 and afterwards turned horizontally. 
 
 The uterus is the receptacle which receives the ovum, 
 retains it for nine months to bring it to maturity, and 
 then expels it by virtue of its muscular walls. Its situation and 
 peritoneal connections have been described (p. 409). We have now 
 to notice that its axis slants forwards, so that, upon the whole, the 
 axis of the vagina and uterus describes a curve nearly parallel to 
 the axis of the pelvis. The uterus, then, is so placed that it is ready 
 to rise out of the pelvis into the abdomen after the embryo has at- 
 tained a certain size. 
 
 The uterus in the unimpregnated state is pyriform, or rather tri- 
 angular with the angles rounded, and is somewhat flattened antero- 
 posteriorly. Its average size is about three inches long, two inches 
 broad, and one inch thick, at the upper part : but there is variety 
 in this respect, arising from age, the effect of pregnancies, and other 
 causes. 
 
 For convenience of description, the organ is divided into the 
 fnndus, the body, and the cervix. The term fundus is applied to 
 that part which lies above the level of the Fallopian tubes, and is 
 the broadest part of the viscus (p. 41 9). The body is the central part, 
 while the cervix is the narrow part which projects into the vagina. 
 The vagina is very closely attached round the neck of the uterus : 
 observe that it is attached higher up behind than in front. The 
 mouth of the uterus is at the apex of the neck. This is called the 
 ' os uteri, and by the old anatomists the ( os tinccej from its fancied 
 resemblance to the mouth of a tench. 
 
 Postponing for the present the examination of the interior of the 
 vagina and uterus, let us pass on to the vessels and nerves of these 
 organs. 
 
 Uterine and ^- n addition to the ovarian arteries (which correspond 
 vaginal to the spermatic arteries in the male) given off from the 
 abdominal aorta (p. 335), each internal iliac artery fur- 
 nishes a branch to the uterus and another to the vagina. 
 
 The uterine artery proceeds from the anterior division of the in- 
 ternal iliac, towards the neck of the uterus, between the layers of 
 
414 CONTENTS OF FEMALE PELVIS. 
 
 the broad ligament, and then ascends tortuously by the side of the 
 uterus, giving off numerous branches to it, which anastomose freely 
 with each other. The fundus of the uterus is mainly supplied with 
 branches from the ovarian arteries. 
 
 The vaginal artery ramifies along the side of the vagina, and 
 sends branches to the lower part of the bladder and the rectum. 
 
 The veins, corresponding with the arteries, form the uterine 
 and vaginal plexuses, which empty themselves into the internal 
 iliac. 
 
 The nerves of the uterus are derived from the third 
 Nerves of the an( j f ourtn sacra l nerves, and from the hypogastric 
 
 uterus. J L 
 
 plexus (p. 356). They accompany the blood vessels 1 in 
 the broad ligament to the neck of the uterus, and ascend with 
 them along the sides of the organ. 
 
 Some very small filaments continue with the vessels, and form 
 around them plexuses, upon which, according to the dissections of 
 Mr. Beck,* minute ganglia are found. But most of the nerves 
 soon leave the vessels, and, subdividing, sink into the substance of 
 the uterus, chiefly about its neck and the lower part of its body. 
 A branch may be traced passing up to the fundus of the uterus, 
 and another to the Fallopian tube. 
 
 Whether the nerves of the uterus enlarge during pregnancy, 
 like the arteries, is a question still undecided. Surgically speak- 
 ing, the os uteri may be said to have no nerves ; for it is insensible 
 to the cautery and to the knife. 
 
 The absorbent vessels of the uterus are small in its unim- 
 pregnated state, but greatly increase in size when it is gravid. 
 Those from the fundus and the ovaries proceed with the ovarian 
 vessels to the lumbar glands ; thus explaining the affection of 
 these glands in ovarian disease. Those from the body and the 
 lower part of the uterus accompany the uterine artery, and join 
 the glands in the pelvis; some, however, run with the round 
 ligament to the groin ; hence, in certain conditions of the uterus, 
 the inguinal glands may be affected. 
 
 * Philosophical Transactions for 1846. 
 
CONTENTS OF FEMALE PELVIS. 415 
 
 Structure of ^ ie uterus 5 vagina, ovaries, and Fallopian tubes 
 the vagina, should now be collectively removed from the pelvis 
 ovaries and ^ or *k e P ur P ose f examining their internal structure. 
 Fallopian The vagina having already been laid open (p. 412), we 
 
 observe that it is lined by a mucous membrane of a 
 pale rose colour; and that it is rough and furrowed, especially 
 near the orifice. A more or less prominent ridge runs along its 
 anterior ; another, along its posterior wall. From either side of 
 these, called ' columnce rugarum,' proceed a series of transverse 
 ridges with rough, jagged margins directed forwards. They are 
 well marked in virgins, but repeated parturition and increasing 
 age gradually smooth them down. The use of the vaginal rugae 
 is to excite the sensibility of the glans in coition. They them- 
 selves also possess keen sensibility, being richly endowed with 
 papillae. 
 
 The mucous membrane has a thick lining of squamous epithe- 
 lium, and in the submucous tissue is an abundant supply of mucipa- 
 rous glands, which increase in number and size towards the uterus. 
 The chief strength of the vagina depends upon a fibro-cellular 
 coat, about one-twelth of an inch in thickness. If this coat be 
 minutely injected, we find that it is composed mainly of the inos- 
 culations of blood vessels, so much so, that by some it is regarded 
 as erectile tissue. In this coat, muscular fibres, longitudinal and 
 circular, have been demonstrated. The orifice of the vagina is 
 surrounded by a circular muscle, called 'sphincter v'agince' (p. 407). 
 Before the uterus is laid open, examine the shape of 
 
 that portion of the neck which projects into the vagina. 
 The back part of the cervix appears to project into the vagina 
 more than the front; but this arises from the vagina being 
 attached higher up behind it. If the vagina were cut away from 
 the cervix, the anterior lip of the uterus would appear to project a 
 trifle more than the posterior. For this reason, as well as on 
 account of the natural slope forwards of the uterus, the front lip 
 is always felt first in an examination per vaginam.* The length, 
 
 * This is the only way to reconcile the discrepancies one meets with in anatomical 
 works, respecting the comparative length of the lips of the uterus. Kraus, Weber, 
 
116 CONTENTS OF FEMALE PELVIS. 
 
 however, and the general appearance of the vaginal part of the 
 cervix vary according to the age of the individual ; it is also con- 
 siderably altered by parturition. In the adult virgin it is smooth 
 and round, and projects about half an inch : its mouth is a small 
 transverse fissure. But after parturition, it loses "its plumpness, 
 the lips become flaccid and fissured, and the mouth larger than it 
 was before.* 
 
 The uterus must now be laid open by a longitudinal incision, to 
 examine its interior. In doing so, observe the thickness of its 
 walls, which is greatest towards the fundus. Before coming into 
 the proper cavity in the body of the uterus, you must slit up a 
 long narrow canal which leads up into it through the neck. This 
 canal is not of the same dimensions throughout: it is dilated in the 
 middle, and gradually narrows towards each end. The upper end, 
 which leads into the body of the uterus, is called ' os internum,' 
 the lower end, which leads into the vagina, ' os externum.' The 
 passage is called the ' canal of the cervix.' It remains unchanged 
 in pregnancy for some time after the cavity in the body has ex- 
 panded, but gradually disappears with the increasing size of the 
 embryo. 
 
 The shape of the cavity in the body of the uterus is triangular, 
 with the apex towards the cervix. In a virgin uterus the cavity is 
 very small, and its sides are convex ; but in a uterus which has 
 borne many children, the cavity has lost the convexity of its sides, 
 and has increased in capacity. Each angle at the base is some- 
 what prolonged, and leads to the minute opening of the Fallopian 
 tube. This prolongation of the angles is noticed more or less in 
 
 Busch, and others, say the anterior is the longer ; Mayer, Meckel, Quain, and others, 
 the posterior. 
 
 * Instances are recorded in which the neck of the uterus is preternaturally long. It 
 has been known to project even as much as an inch and a half into the vagina. In 
 such cases it gradually tapers, and terminates in a very narrow mouth. This is said 
 to be one cause of sterility, and it is recommended either to dilate the'Tnouth, or to 
 cut off a portion of the neck. In support of this opinion, it is stated that Dupuytren 
 was once consulted by a lady on account of barrenness ; finding the neck of the uterus 
 unusually elongated, he removed a portion of it, and in due time the lady became 
 pregnant. (Hyrtl, Handbuch der top. Anatom.) 
 
CONTENTS OF FEMALE PELVIS. 417 
 
 different females, and is the last indication of the two horns of the 
 uterus in some orders of mammalia. 
 
 The interior of the uterus is smooth at the fundus ; but the 
 reverse at the cervix. Here there is a central longitudinal ridge, 
 both in front and behind (as in the vagina) ; from these, other 
 closely set oblique ridges curve off laterally, like the branches of a 
 palm-tree. The old anatomists called it ' arbor vitce. 9 The 
 roughness produced by these ridges, occasions an impression as 
 though we were touching cartilage when a metallic sound is in- 
 troduced into the uterus. 
 
 The neck of the uterus is provided with small muciparous glands, 
 of which the minute ducts open in the furrows between the ridges 
 referred to. The secretion of these glands is glairy, albuminous, 
 and slightly alkaline. Soon after conception, the secretion dries up 
 so as to plug the mouth of the uterus, but shortly before and 
 during parturition it is poured out in great quantity, to facilitate 
 the passage of the child. It happens, occasionally that one or 
 more of the ducts of these glands become obstructed, and then 
 dilate into small transparent vesicles, which gradually rise to the 
 surface and burst. These were first described by Naboth,* and 
 supposed to be true ova : hence their name ' ovula Nabothi.' 
 
 The mucous membrane of the uterus is much more delicate than 
 that of the vagina, with which it is continuous, and is closely 
 united to the subjacent tissue. The greater part of it is lined by 
 a columnar ciliated epithelium, but that which lines the cervix is 
 squamous, like that of the vagina. Examined with a lens, the mucous 
 membrane lining the body of the uterus is seen to be covered with 
 minute follicles or tubes arranged at right angles to its surface. 
 These follicles consist of simple tubes which pass outwards in a 
 spirally coiled manner, some of them appearing branched and 
 dilated at their extremities. These tubes become greatly developed 
 shortly after impregnation, and are presumed to take an important 
 part in the formation of the ' membrana decidua.' 
 
 The greater portion of the walls of the uterus consists of muscular 
 fibres of the unstriped or involuntary kind, which are chiefly 
 
 * De sterilitate inulierum. Lips., 1707. 
 E E 
 
418 CONTENTS OF FEMALE PELVIS. 
 
 aggregated at the fundus, and less so at the junction of the Fallopian 
 tubes. The texture of these fibres is so close that in the unim- 
 pregnated uterus it is useless to attempt to make them out 
 satisfactorily. The muscular fibres are arranged in three layers, 
 external, middle, and internal. The external layer, placed imme- 
 diately beneath the peritoneum, is thin, and its fibres run trans- 
 versely round the uterus, some of them being continued into the 
 round and broad ligaments. A band of longitudinal fibres passes 
 from the anterior surface of the uterus round .the fundus to its 
 posterior aspect. The middle layer runs in all directions, and 
 chiefly surrounds the blood vessels. The internal layer is composed 
 mainly of concentric circles which surround the orifices of the 
 Fallopian tubes ; at the cervix its fibres are arranged transversely 
 round it, forming a kind of sphincter. Upon the whole their 
 collective disposition is such as to exert equal pressure on all 
 sides, when called into operation. 
 
 At the same time that they expel the foetus, the muscular fibres 
 perform another very important function : they close the large 
 venous sinuses developed for its nutrition. Therefore, little hae- 
 morrhage accompanies the expulsion of the placenta, provided it 
 have been attached to the fundus or the side of the uterus. But 
 every one knows the danger of what is called ( placenta prceviaS 
 Here, the placenta, placed over the orifice of the uterus, is attached 
 to a part of the organ which must of necessity expand during 
 labour ; and every uterine contraction increases, instead of check- 
 ing, the bleeding. For the same reason, paralysis of the mus- 
 cular fibres in immediate connection with the placenta, be it 
 where it may, is likely to be a source of serious hemorrhage in 
 parturition. 
 
 The Fallopian tubes or oviducts are situated, one on 
 each side, along the upper border of the broad liga- 
 ment of the uterus, and convey the ovum from the 
 ovary to the uterus (fig. 90). They are about four or five inches 
 in length. One end opens into the uterus ; the other terminates in 
 a wide funnel-shaped mouth, surrounded by fringe-like processes 
 called the ' fimbriated extremity.' This termination of the Fal- 
 
CONTENTS OF FEMALE PELVIS. 
 
 419 
 
 lopian tube extends about an inch beyond the ovary ; and, by 
 floating it in water, one or two of the fimbriae may be seen con- 
 nected with the outer end of the ovary. If the Fallopian tube be 
 opened from the expanded end, and a probe introduced into it, 
 you will find that the tube runs very tortuously at first, then 
 straight into the uterus, gradually contracting in size, so that the 
 uterine orifice scarcely admits a bristle. Its mucous lining is 
 gathered into longitudinal wavy folds, especially at the ovarian 
 end, and is provided with a columnar ciliated epithelium. The 
 free end of the tube communicates with the cavity of the peri- 
 toneum. This is the only instance where a mucous membrane is 
 
 DIAGRAM OF THE UTERUS, ITS BROAD LIGAMENTS, THE OVARIES, AND FALLOPIAN TUBES. 
 
 1. Uterus. 
 
 2. Ovary. 
 
 3. Fallopian tube. 
 
 4. Fimbriated extremity of Fallopian tube. 
 
 5. 5. Broad ligament. 
 
 6. Vagina. 
 
 directly continuous with a serous one. It explains how the em- 
 bryo may escape into the peritoneal cavity ; though this is an 
 extremely rare occurrence. It also explains what is said to have 
 occurred ; namely, the escape of the fluid in dropsy through the 
 Fallopian tubes. In a well-injected subject, the Fallopian tubes are 
 seen to be well supplied with blood from the ovarian arteries. 
 They are provided with unstriped muscular fibres ; the outer 
 layer being arranged longitudinally, the inner, in circles. 
 
 The ovaries (called by Gralen, ' testes muliebres ') 
 are suspended to the back of the broad ligament of the 
 
 E E 2 
 
 Ovaries. 
 
420 CONTENTS OF FEMALE PELVIS. 
 
 uterus by a short peritoneal fold, which transmits their proper 
 vessels and nerves : besides this, they are connected on their inner 
 side to the uterus by a thin cord, called the ligament of the ovary. 
 They are of an oblong form, with the long axis transverse, and a 
 little smaller than the testicles. In females who have not often 
 menstruated, their surface is smooth and even ; in after-life, they 
 become puckered and scarred by the repeated escape of the ova. 
 
 The ovary is about an inch and a half long, and weighs about 
 a drachm and a half. It has nearly the same coverings as the 
 testicle ; viz. a serous coat, and beneath it a proper fibrous coat, 
 the ( tunica atbuginea? If a section be made through the ovary, 
 you find that it contains transparent vesicles, embedded in a soft 
 fibrous-looking tissue, remarkably vascular when well injected, 
 called the ( stroma ' of the ovary. The outer part of the ovary is 
 chiefly occupied by these vesicles ; the central part, in which there 
 are very few, is composed almost entirely of the stroma. 
 
 The transparent vesicles just alluded to are the ovisacs or 
 * Graafian ' * vesicles. They vary in number from eight to thirty, 
 and in size from that of a pin's head to a pea. The smallest 
 are near the centre ; but as they advance towards maturity, they 
 gradually approach the surface, increasing at the same time in 
 size. They contain a transparent albuminous fluid. On examining 
 the contents of one of the larger vesicles under the microscope, you 
 find in it the ovum or germ,f surrounded by a layer of granular 
 cells called the ' disc as proligerus.' It is this ovum which, 
 escaping from the Graafian vesicle on the surface of the ovary, is 
 grasped by the Fallopian tube and conveyed into the uterus. The 
 ruptured vesicle is converted soon afterwards into a yellowish- 
 looking mass called ' corpus luteumj which persists for a while, 
 and degenerates afterwards into a small fibrous cicatrix. 
 
 The ramifications of the ovarian artery through the ovary are 
 remarkable for their convolutions : they run in parallel lines, as 
 in the testicle. Its nerves are derived from the ovarian plexus. 
 
 * So called after De Grraaf, a Dutch anatomist, who discovered them in 1672, and be- 
 lieved they were the true ova. 
 
 f This was first distinctly pointed out by Von Baer in 1827. 
 
ANATOMY OF THE LIVER. 421 
 
 The ovarian veins terminate, like the spermatic in the male ; the 
 right in the vena cava, the left in the renal. 
 
 DISSECTION OF THE ABDOMINAL VISCEEA. 
 
 The liver is the largest gland in the body, and in the 
 The liver. . ~? 
 
 adult weighs from three to four pounds. Its surface 
 
 is entirely covered by peritoneum, except a small part behind, 
 which is connected to the diaphragm by cellular tissue, and in the 
 hollow for the gall-bladder : behind, the liver is..thick and round, 
 but towards the front it gradually slopes to a thin border. The 
 upper surface of the liver is smooth and convex, in adaptation to 
 the diaphragm, and is marked by a white line which indicates its 
 division into a right and left lobe, the right being the larger. The 
 under surface is irregular and marked by five fissures and five 
 lobes : 1. The longitudinal fissure, which divides the 
 right from the left lobe, contains the round ligament 
 (the remains of the umbilical vein). 2. The continuation of the 
 longitudinal fissure to the posterior border of the liver, contains 
 the remains of what was, in the foetus, the ductus venosus, and is 
 therefore called the ' fissure of the ductus venosus' 3. The 
 hollow or * fissure for the gall-bladder.'' In the same line with 
 this is, 4, the s fissure of the inferior vena cavaj which passes 
 obliquely inwards towards the posterior border of the liver. 5. 
 The ' transverse fissure ' unites the other fissures, and transmits 
 the great vessels which enter the liver in the following order: in 
 front is the hepatic duct, behind is the vena porta, and between 
 them the hepatic artery. The relative position of these fissures 
 may be best impressed on the memory by comparing them col- 
 lectively to the letter H. The transverse fissure represents the 
 cross-bar of the letter ; the longitudinal fissure and the fissure of 
 the ductus venosus represent the left bar ; the fissures of the gall- 
 bladder and vena cava make the right bar. 
 
 The lobes of the liver, five in number, are also seen 
 on its under surface. The right lobe, much larger 
 than the left, is separated from it by the longitudinal fissure. On 
 
422 
 
 ANATOMY OF THE LIVEK. 
 
 the under surface of the right lobe are two shallow depressions ; 
 the anterior is for the colon, the posterior for the kidney. The 
 remaining lobes may be considered as forming parts of the right 
 lobe, and are, the lobulus Spigelii, the lobulus caudatus, and the 
 lobulus quadratus. The lobulus Spigelii is placed between the 
 fissures of the ductus venosus and vena cava; and behind the 
 transverse fissure it is connected to the right lobe by a ridge the 
 lobulus caudatus. The lobulus quadratus is situated between the 
 
 Fig. 91. 
 
 1 . Longitudinal fis- 
 
 sure. 
 
 2. Continuation of 
 
 the longitudi- 
 nal fissure (for 
 the ductus ve- 
 nosus) . 
 
 3. Transverse fis- 
 
 sure. 
 
 4. Gall-bladder. 
 
 5. Vena cava in its 
 
 groove. 
 
 6. Right lobe. 
 
 7. Left lobe. 
 
 8. Lobulus Spigelii. 
 
 9. Lobulus cauda- 
 
 tus. 
 
 10. Lobulus quad- 
 ratue. 
 
 DIAGRAM OF THE UNDER SURFACE OF THE LIVER. 
 
 gall-bladder and the longitudinal fissure. This lobe is occasionally 
 connected with the left lobe by a bridge of hepatic substance 
 (pons hepatis) which arches over the longitudinal fissure. 
 
 The liver has a thin areolar coat or capsule, best seen on those 
 parts of it not covered by peritoneum. This coat is connected to 
 the fine areolar tissue which surrounds the lobules, but does not 
 send down partitions to form a framework for the interior of the 
 gland. It is continuous, at the transverse fissure, with the sheath 
 of loose areolar tissue called ' Glissorts capsule? which surrounds 
 the vessels as they enter that fissure, and incloses them in a 
 common sheath in their ramifications through the liver. 
 
 The interlobular areolar tissue is exceedingly delicate: hence, 
 
ANATOMY OP THE LIVER. 
 
 423 
 
 the great liability of the liver to be lacerated by external violence, 
 or by the action of the abdominal muscles. 
 
 The liver consists of an aggregation of 'lobules*' 
 
 Lobules. -I i r- 
 
 which range from ^th to T Vth of an inch in diameter. 
 These lobules vary in shape according to the direction in which 
 they are cut ; in a transverse section, they have the appearance of 
 mosaic pavement (fig. 92) ; but in a perpendicular section they 
 somewhat resemble an oak leaf (fig. 93). Each lobule consists of a 
 
 Fig. 92. 
 
 a. Inter-lobular vein. 
 
 6. Intra-lobular vein. 
 
 TRANSVERSE SECTIONS OF THREE LOBULES OF THE LIVER, MAGNIFIED TO SHOW THE 
 PORTAL VENOUS PLEXUS. 
 
 (After Kiernan.) 
 
 minute plexus of blood vessels, ducts, and cells hepatic cells 
 which latter fill up the spaces between the ramifications of the 
 vessels. It will facilitate the understanding of the branchings of 
 the different hepatic vessels, if it be borne in mind, 1, that the 
 portal vein, hepatic artery, and hepatic duct, ramify together from 
 first to last they are inclosed in a sheath of areolar tissue called 
 6 Grlisson's capsule ; ' 2, that the hepatic veins run from first to 
 last by themselves, and terminate in the inferior vena cava as it 
 passes through the liver. 
 
 The portal vein on entering the substance of the liver gives off 
 numerous small branches which pass between the lobules and form 
 
424 ANATOMY OF THE L1VEK. 
 
 the ' inter-lobular veins ' (fig. 92). Some inter-lob ular veins are also 
 Fig. 93. derived from branches (vaginal 
 
 veins) of the portal vein, which 
 before passing between the lobules 
 ramify in Grlisson's capsule. A 
 minute capillary network arises 
 from the inter-lobular veins, and 
 penetrates into the interior of the 
 lobules, in the centre of which it 
 
 LONGITUDINAL SECTIONS OF THE collects into a single trunk called the 
 
 LOBULES OF THE LIVER. INTRA- . . . 777 mi 
 
 1 intra-lobular vein. This central 
 
 LOBULAR VEINS SEEN 
 
 THE SUB-LOBULAB. vein opens into a sub-lobular vein, 
 
 larger or smaller as the case may be, upon which the lobule is 
 sessile (fig. 93). The sub-lobular veins empty themselves into the 
 smaller hepatic veins ; these unite to form the main hepatic trunks 
 which open into the inferior vena cava. 
 
 The hepatic artery, entering the liver at the transverse fissure, 
 divides and subdivides with the portal vein, and ramifies with it 
 between the lobules. The artery distributes branches which supply 
 the coats of the hepatic vessels, Grlisson's capsule, and the capsule 
 of the liver ; other branches run between the lobules, pass into 
 their substance, and terminate in the capillary network. 
 
 The hepatic ducts form a close network round the circumference 
 of each lobule. From this network, branches proceed on all sides, 
 and accompany the portal vein. Doubt still exists as to the 
 commencement of the ducts. The prevalent opinion is that they 
 begin within the lobules by a minute plexus, surrounded by 
 hepatic cells. The interior of each lobule, that is, the space left 
 between the several vessels, is filled by the hepatic cells. They 
 are nucleated, and have a diameter varying from ^-^th to T oVo^ Q 
 of an inch. They contain more or less granular matter, and in 
 some cases fat globules : when these accumulate in large quantities, 
 they constitute what is called a ' fatty liver/ The office of these 
 cells is to separate the bile from the blood, and when filled with 
 bile, discharge their contents into the hepatic ducts.* 
 
 * For further information on this subject see the original observations of Kiernan 
 in the Philosoph. Trans, for 1833. 
 
GALL-BLADDER AND SPLEEN. 425 
 
 The functions of the liver may be thus briefly expressed: 1. 
 It renders the albuminous matter (albuminose) brought to it by 
 the portal vein capable of being assimilated by the blood. 2. It 
 forms a substance closely allied to sugar, which passes into the 
 hepatic veins, and being consumed in the process of respiration, 
 helps to maintain animal heat. 3. It secretes the bile, which 
 assists in converting the chyme into chyle, and reducing it into 
 a state fit to be absorbed by the lacteals. 4. The bile acts as a 
 natural aperient. 5. The bile is an antiseptic, and probably pre- 
 vents the food becoming decomposed during its passage through 
 the intestines. 
 
 The gall-bladder, a reservoir for the bile, is confined 
 
 Gall-bladder. , ,, ., '. ,. j . ., 
 
 by the peritoneum in a slight depression on the under 
 surface of the right lobe of the liver (p. 422). It is pyriform in 
 shape, and varies in size in different subjects; generally speaking, 
 it is about four inches long, and capable of holding about 1J oz. 
 of fluid. Its narrow end, or neck, makes a bend downwards, and 
 terminates in a duct, called the ( cystic J which, after a course of 
 about an inch and a half, joins the hepatic duct at an acute 
 angle (fig. 67, p. 338). The common duct, ' ductus communis 
 chotedochusj formed by their union, is about three or four inches 
 long, and opens into the back of the descending part of the duo- 
 denum, after running very obliquely through the coats of the 
 bowel. 
 
 Exclusive of its partial peritoneal covering, the gall-bladder has 
 two coats the outer, consisting of fibro-cellular tissue, contains 
 involuntary muscular fibres, which run mainly in the long axis of 
 the gall-bladder; the inner is the mucous coat. 
 
 The gall-bladder should now be laid open. Its mucous mem- 
 brane is generally tinged yellow by bile, and gathered into ridges 
 which give it a honey-comb appearance. This appearance is most 
 marked in the middle of the gall-bladder : in the depressions 
 between the ridges may be seen with a magnifying glass nume- 
 rous openings leading down to mucous follicles. It is covered by 
 columnar epithelium, which secretes an abundance of viscid 
 mucus. At the bend of the neck of the gall-bladder, both its 
 
426 SPLEEN. 
 
 coats project very much into the interior, making the opening 
 considerably narrower than it appears to be outside. In the cystic 
 duct, the mucous membrane presents a series of folds, so arranged, 
 one after the other, as to form a complete spiral valve. The pro- 
 bable use of this is to prevent the too rapid flow of the bile. 
 The gall-bladder appears to serve mainly as a reservoir for the 
 bile, during the cessation of digestion. The bile becomes during 
 its sojourn in the gall-bladder very viscid and intensely bitter. 
 
 The spleen is a very vascular spongy organ, and be- 
 longs to the class of ductless glands. It varies in size 
 according to the amount of blood in it, fluctuating in weight, 
 consistently with health, between five and ten ounces. Usually it is 
 of a reddish-blue colour, owing to the large amount of blood con- 
 tained in it. It is more or less elliptical in shape, and in its natural 
 position is placed with its long axis nearly vertical. Its outer 
 surface, adapted to the diaphragm and ribs, is smooth and convex ; 
 its inner, adapted to the great end of the stomach, is concave, and 
 divided into an anterior and a posterior portion by a vertical 
 fissure the hilus &t the bottom of which are large openings 
 through which the vessels enter and emerge from the spleen. 
 
 The spleen is invested with two coats, a peritoneal and a fibrous. 
 The peritoneal coat entirely covers the organ, except at the hilus, 
 from which it is reflected to the stomach, forming the gastro-splenic 
 omentum. Its fibrous capsule covers the spleen, and is elastic, 
 to accommodate itself to the varying size of the viscus. This 
 coat is intimately connected with the splenic substance, and in it 
 are said to be some involuntary muscular fibres. It sends down 
 into the interior numerous bands trabeculce which cross each 
 other in various directions, and form a network, dividing the spleen 
 into many chambers. Besides constituting the general framework 
 of the organ, the capsule at the hilus forms sheaths for the vessels, 
 and supports them throughout their ramifications in the interior. 
 
 The splenic chambers are filled with a soft, reddish-brown sub- 
 stance, called the 'pulp' of the spleen. Under the microscope it 
 is found to consist mainly of cells, of a pale red colour, somewhat 
 smaller than the red corpuscles of the blood. Interspersed among 
 
SPLEEN. 427 
 
 these are numerous other cells, some caudate, others nucleated, and 
 others altered blood-cells either free or contained within larger cells. 
 In the pulp are found numerous white spherical bodies, 'Malpighian 
 corpuscles -,' of about the -^th of an inch in diameter.* These cor- 
 puscles are not free like the smaller cells, but are attached by 
 slender pedicles to the walls of small arteries, from whose sheaths 
 the capsules of these bodies are derived. The artery ramifies over 
 the surface of the corpuscles, and then terminates in a brush of 
 capillaries, which spread out into the pulp. The interior of each 
 corpuscle is filled with a whitish fluid, containing numerous 
 small granular cells. 
 
 The splenic artery enters the spleen by several branches, which 
 ramify throughout the organ, supported by sheaths derived from the 
 capsule.| These branches subdivide in the trabecular tissue, and 
 the small ramifications spread out in a brush-like manner through 
 the pulp, and terminate in capillaries which open into the veins (and 
 also, according to Gray, into lacuriar spaces from which the veins 
 originate). The main branches of the artery do not communicate 
 with one another, for if injection be thrown separately into one 
 branch, it fills only that part of the spleen to which the artery is 
 distributed. 
 
 Thus it appears that the spleen is essentially a great blood 
 gland ; and that it consists of chambers filled with secreting gland 
 cells of various size, between which ramify minute arteries and 
 veins. It is presumed that the gland elaborates the albuminous 
 materials of food, and stores them up for a time before they pass 
 into the blood. It is considered to be a nursery for the production 
 of the white corpuscles of the blood ; and a grave-yard too, where 
 many of the worn-out red ones undergo disintegration. 
 
 The kidneys are situated in the lumbar region, im- 
 Kidneys. bedded in a large quantity of fat. Their colour is 
 
 * In the human spleen they vary from ^th to ^th of an inch in diameter. It is 
 useless to look for them unless the subject be exceedingly fresh, for they soon soften 
 and melt in the pulp. It is better, therefore, to examine them in the spleen of a sheep 
 or bullock, in which animals they are about ~th of an inch in diameter. 
 
 f" The ramifications of the splenic artery may be well seen by washing away the 
 pulp, and floating the flocculent-looking spleen in water. 
 
428 
 
 KIDNEY. 
 
 Fig. 94. 
 
 reddish-brown. Each weighs about five ounces in the male, rather 
 less in the female. The left is usually longer and somewhat 
 heavier than the right. The anterior surface of each is smooth 
 and convex ; the posterior rather flattened. The outer border is 
 rounded; the inner presents a deep notch the hilus for the 
 entrance and exit of the renal vessels and duct. These have the 
 following relations to one another : in front lies the renal vein ; 
 behind is the ureter ; between them the renal artery. 
 
 The kidney is surrounded by a 
 thin fibrous capsule, to which it is 
 loosely connected by areolar tissue 
 and minute vessels. The capsule 
 does not penetrate into the interior 
 of the kidney, and can, for this 
 reason, when healthy, be readily 
 stripped off, leaving the surface 
 perfectly smooth. 
 
 A longitudinal section should be 
 made through the kidney to ex- 
 amine its interior. This section 
 displays two distinct substances, an 
 outer or cortical, and an inner or 
 medullary. 
 
 The medullary structure is col- 
 lected into from ten to sixteen 
 pyramidal bundles (pyramids of 
 Malpighi,* fig. 94); the apices 
 of these, termed ( papillcej pro- 
 ject into one of the terminal di- 
 visions of the excretory tube. 
 These pyramids are composed of minute straight tubes, which 
 proceed from the cortical portion to end on the papillae, f 
 
 * So named after Malpighi, a celebrated Italian anatomist who lived during the 
 middle and latter part of the seventeenth century. 
 
 f Each pyramid represents what was, in the early stage of the kidney's growth, a 
 distinct and independent lobe. In the human subject the lobes gradually coalesce, 
 
 SECTION OF THE KIDNEY. 
 
 1. Ureter. 
 
 2. Pel vis of the kidney. 
 
 3. 3, 3. Papillae. 
 
KIDNEY. 429 
 
 The cortical structure, deeper in colour than the medullary, 
 forms the outer part of the kidney, and dips down between the 
 pyramids. It consists of convoluted tubes, and of small red bodies, 
 called Malpighian corpuscles. 
 
 At the ( hilus ' is the dilated commencement of the ureter, called 
 the pelvis of the kidney. It is funnel-shaped, and its broad part 
 divides into two principal channels, which again branch and form 
 from eight to twelve cup-like excavations, called the calices. Into 
 each of these calices one, sometimes two, papillae project. Between 
 the calices the branches of the renal artery ascend to ramify in 
 the kidney, lying imbedded in a quantity of fat. With a lens, 
 the papillae may be seen studded with minute apertures, which are 
 the terminations of the uriniferous tubes. These tubes as they 
 pass outwards run straight, bifurcate repeatedly, and enter the 
 cortex in bundles of straight tubes, forming the ( pyramids of 
 Ferrein.' They vary from the g-J^th to -g-J-Q-th of an inch in dia- 
 meter, and are largest towards their termination. On entering 
 the cortex, the tubes become convoluted, and are surrounded by 
 minute plexuses of blood vessels. The tubuli uriniferi, the pelvis 
 of the kidney, and the ureter, are lined by spheroidal epithe- 
 lium.* 
 
 The Malpighian corpuscles are situated in the cortical portion, 
 and average about -r^th of an -inch in diameter. According to 
 Bowman,! each is formed by the dilatation of the uriniferous 
 tube. It is composed of a homogeneous membrane, and is pierced 
 by a small artery, which enters the capsule opposite to the com- 
 mencement of the urinary tube. In the capsule the artery breaks 
 up into a coil of minute vessels (glomerulus), which returns its 
 blood by a vein (efferent vessel), which emerges from the capsule 
 
 and no trace of their primordial state remains, except the pyramidal arrangement of 
 the tubes. But in the kidneys of the lower mammalia, of birds and reptiles, the lobes 
 are permanently separate. 
 
 * Between the straight tubes in the Malpighian pyramids, there have recently been 
 discovered numerous smaller tubules, named the looped tubes of Henle. These are 
 said to come off from the straight tubes, to descend towards the apex of the pyramid, 
 where they form loops, and again ascend to terminate in the Malpighian corpuscles. 
 
 f Philosoph. Trans, for 1842. Part I. 
 
430 
 
 RENAL CAPSULES. 
 
 
 a. Artery. 
 
 d. urinary tube. 
 
 close to where the artery entered. Instead of leaving the kidney, 
 as in other organs, it forms a venous plexus round the convolutions 
 of the urinary tube.* The special purpose of 
 this plexus appears to be the secretion of the 
 solid matter of the urine ; while the Malpighian 
 body niters the watery part of the urine into the 
 capsule, and washes the more solid part down 
 the tube.f The coil of vessels in the capsule is 
 surrounded by the epithelium lining the interior 
 of the capsule. 
 
 The nerves forming the renal plexus are de- 
 rived from the smallest splanchnic nerves and 
 the solar plexus. The lymphatics pass to the 
 lumbar glands. 
 
 These bodies, situated at the top of 
 the kidneys, belong to the class of 
 ductless glands. The right resembles 
 a cocked hat, the left is more almond-shaped. 
 They measure about 1 inch in their long diameter, and weigh 
 from one to two drachms. They are surrounded by a thin fibrous 
 covering, which sends down partitions into the interior through 
 furrows upon their surface. 
 
 A perpendicular section shows that it consists of a firm exterior 
 or cortical part, and of an interior or medullary substance, soft and 
 pulpy. The cortical portion is of a yellow colour, and forms the 
 principal part of the organ. Examined under the microscope, it 
 appears to be composed of clusters of columns about y^-th of an 
 inch in diameter, arranged perpendicularly to the surface. These 
 columns do not run completely through the thickness of the 
 cortical portion, but have a layer of cells arranged above and below 
 
 * For a summary of the opinion held by various observers, respecting these Mal- 
 pighian corpuscles, consult a paper by K. Sou they, M.D., St. Bartholomew's Hosp. 
 Keports, vol. i. 1865. 
 
 f That the vessel leaving the Malpighian body is a vein, and that a constituent 
 part of the urine is secreted by venous blood, is inferred from two reasons : 1. From 
 the analogous case of the vena porta, out of which the bile is elaborated in the liver ; 
 2, from the fact that in reptiles the urine is secreted from venous blood. 
 
STRUCTURE OF THE STOMACH. 431 
 
 them.* The columns lie in the stroma of the cortex, which con- 
 tains oval nucleated cells, large fat globules, and a number of 
 minute yellowish granules. The columns are stated by some to 
 be tubes having a distinct lining membrane; by others, to be 
 closed vesicles ; and by others to be cavities in the cortical por- 
 tion. Small arteries are abundantly supplied to the cortex, and 
 dip down between the columns. The medullary part varies in 
 colour according to the amount of blood contained in it, being in 
 some of a dark brown colour, in others nearly white. It consists 
 of a plexus of minute veins, among which are numerous cells, some 
 of whch appear branched, f The stroma is composed of areolar 
 tissue, which forms a delicate network throughout the central 
 part. 
 
 Of late years the minute structure and functions of the renal 
 capsules have been much investigated, in consequence of the dis- 
 covery, made by Dr. Addison, of the close relation which exists 
 between certain diseases in these bodies and a brown discoloration 
 of the skin. Their precise function is still unknown. 
 
 The alimentary canal is composed of four coats ; a 
 intestines 811 serous ? a muscular, a sub mucous, and a mucous. First, 
 is the serous or peritoneal coat, described at p. 332. 
 Secondly, under the serous is a muscular coat, upon which the 
 chief strength of the canal depends. It consists of two distinct 
 strata of fibres ; the outer stratum is longitudinal, the inner cir- 
 cular. This arrangement not only makes the bowel stronger, 
 but regulates its peristaltic action ; for the longitudinal fibres, by 
 their contraction, tend to shorten and straighten the tube, while the 
 circular fibres contract upon and propel its contents to greater ad- 
 vantage. Connecting this coat and the mucous, is a layer of 
 areolar tissue called the submucous coat, in which the arteries break 
 up before entering the mucous membrane. The mucous is the 
 most complicated of all the coats, for it presents different characters 
 
 * See an article by D. Duckworth, M.D., on 'The Anatomy of the Supra-renal 
 Capsules,' in St. Bartholomew's Hosp. Reports, vol. i. 1865. 
 
 t Consult ' A Physiological Essay on the Thymus Gland,' by Simon, London, 1845. 
 
432 STRUCTURE OF THE STOMACH. 
 
 in different parts, according to the functions which it has to per- 
 form. 
 
 Stomach ^e s t macn should be moderately distended to see 
 
 its size, which varies in different subjects according to 
 the habits of the individual. In shape it has been compared to the 
 bag of a bag-pipe. When distended it is about twelve inches in 
 length and about four in width. The stomach forms a large bulge 
 to the left of the oesophagus, called the cardiac or ossophageal end : 
 on the right side, where the food passes out, it becomes small and 
 contracted, and is called the pyloric end. Just before the 
 pylorus, the stomach bulges into a pouch, called ' antrum pylori.'' 
 Anatomists describe the stomach as having two borders and two 
 surfaces. The upper border is concave, and called the lesser curve : 
 the lower border is convex and called the greater curve. The 
 surfaces, anterior and posterior, are convex. On removing the 
 serous investment of the stomach, the muscular coat is exposed. 
 The fibres are of the non-striped variety and arranged in three 
 layers, an external or longitudinal, a middle or circular, and an in- 
 ternal or oblique. 
 
 The longitudinal fibres are continuous with the longitudinal 
 fibres of the oesophagus, and spread out over the stomach : they are 
 most numerous along the curves of the stomach. The circular 
 fibres are well marked about the middle of the stomach, but are 
 most abundant at the pylorus, where they form a powerful sphincter 
 muscle. The oblique fibres are scattered over the sides of the 
 stomach, and are the most distinct at the entrance of the oesophagus. 
 
 When the stomach is laid open, the mucous membrane is seen 
 to be of a pale colour, and gathered into longitudinal folds (rugce\ 
 which disappear when the stomach is full. The mucous membrane 
 is connected to the muscular layer by a distinct stratum of areolar 
 tissue, called the s submucous coat .' Its use is to permit the mus- 
 cular and mucous coats to move freely on each other, and to serve 
 as a bed, in which the blood vessels ramify minutely before they 
 enter the mucous membrane. 
 
 If a portion of the mucous membrane be examined under a 
 microscope, its surface will be seen to be mapped out into small 
 
STRUCTURE OP THE SMALL INTESTINES. 433 
 
 hexagonal pits or alveoli, giving it a honey-comb appearance. The 
 pits vary from the T -^oth to -g^th ^ an ^ nc ^ ^ n diameter. At the 
 bottom of them are a number of minute pores, the orifices of the 
 gastric tubes. In a perpendicular section, the tubes are arranged 
 in parallel lines at right angles to the surface, and terminate in 
 blind sacculated ends set in the submucous tissue. The entire 
 thickness of the mucous membrane is made up of these tubular 
 glands. The tubules are on an average about -fatti of an inch long. 
 In the cardiac end they are simple tubes, but at the pyloric end 
 they are frequently branched. Their upper fourth is lined with 
 columnar epithelium, their lower three-fourths, with spheroidal or 
 glandular. It is presumed that these glandular cells contain the 
 gastric juice. As fast as formed, during digestion, they pass into 
 the stomach, discharge their contents, and disappear. Other 
 glands lenticular may be found near the pyloric end of the 
 stomach, and resemble Peyer's glands. 
 
 The mucous membrane of the stomach, and also of the upper 
 part of the interior of the tubes, is lined by a columnar epithe- 
 lium. It is exceedingly thin and delicate, and can only be seen 
 in the stomach of an animal recently killed. 
 
 The tubes of the stomach are richly supplied with blood. The 
 arteries form a stratum of minute inosculations in the submucous 
 tissue, in which the closed ends of the tubes are set ; from this 
 stratum the vessels run up between the tubes to the surface of the 
 stomach, where they again inosculate, and form the hexagonal 
 spaces before alluded to. 
 
 The stomach is supplied with nerves from the pneumogastric 
 and from the solar plexus. 
 
 The small intestines, consisting of the duodenum, 
 fntestines J e j unum * an( ^ ileum, form a tube from sixteen to twenty- 
 six feet in length, according to the height of the indivi- 
 dual. The duodenum is about twelve inches in length; the jeju- 
 num comprises two-fifths, the ileum three-fifths of the remaining 
 part of the small intestine. As regards their external character, 
 the duodenum and jejunum are more vascular than the ileurn, 
 and feel thicker in consequence of the peculiar arrangement of 
 
 F F 
 
434 STRUCTURE OF THE SMALL INTESTINES. 
 
 their mucous membrane. Their peritoneal and muscular coats 
 are the same throughout. The muscular coat consists of an outer 
 thin longitudinal layer and an inner circular thicker layer. It is 
 connected to the mucous membrane by the submucous coat. 
 
 When the small intestines are cut open from the upper end, we 
 observe that the mucous membrane is arranged in close transverse 
 folds or plaits, called ( valvulce conniventes. 1 These differ from 
 other folds in the alimentary canal, e.g. in the oesophagus and 
 stomach, in that they are not obliterated when the tube is dis- 
 tended. Each fold extends about one-half or two-thirds round 
 the intestine ; but they are not all of equal size. They commence 
 immediately below the openings of the biliary and pancreatic 
 ducts, and are most largely developed in the duodenum and 
 the upper part of the jejunum. Below this part of the tube they 
 gradually decrease in size, and become wider apart, till they finally 
 disappear near the middle of the ileum. The use of the valvulse 
 conniventes is, to increase the extent of surface for the absorption 
 of chyle ; to prevent the food passing too rapidly through the 
 intestines, and also for secretion. 
 
 If a portion of small intestine be washed and placed in water, 
 the surface of the mucous membrane appears like the soft fur or 
 pile upon velvet. This appearance is produced by small processes 
 called villi. These are extremely vascular projections of the 
 mucous membrane, about a fourth of a line in length, and so close 
 to each other that a square line contains from forty to ninety of 
 them. Their size, however, and their number, bear a direct ratio 
 to that of the valvulse conniventes. Under the microscope a villus 
 is seen to consist of an outstanding process of the mucous mem- 
 brane, covered by a layer of columnar epithelium, which rests upon 
 its proper basement membrane. Each villus is furnished with an 
 artery which forms a network of inosculations over it, and then 
 returns its blood by a single vein. In its interior it contains a 
 lacteal or absorbing vessel, which commences in a closed end near 
 the summit of the villus, where it is surrounded by a layer of pale 
 unstriped muscular fibres. The cylindrical cells which cover the 
 villi are believed to be the agents in the absorption of the chyle, 
 and to possess the power of selection. 
 
STRUCTURE OF THE SMALL INTESTINES. 435 
 
 There are four kinds of glands * in the small intes- 
 tine called > the gl an ds of Lieberkiihn, Brunn, Peyer, 
 and the solitary glands. The first and last are distri- 
 buted over the whole tract of the intestinal mucous membrane ; 
 the other two over particular parts. 
 
 The glands of Lieberkuhn f are minute tubes with blind ends, 
 very thickly distributed over the small and the large intestines. 
 Under the microscope, their orifices are seen between the villi, like 
 so many minute dots. These vary in depth from ^-th to -^th. of 
 a line, and are lined with columnar epithelium. 
 
 The glands of Brunn^. are found only in the duodenum. They 
 are just visible to the naked eye, and may be seen by removing 
 the muscular coat. Their structure exactly resembles the pan- 
 creas on a diminutive scale. 
 
 The glands of Peyer (glandulse agminatae) abound most in 
 the ileum, and are seen most distinctly in children. They are 
 arranged in groups, from twenty to forty in number, on that 
 part of the intestine most distant from the attachment of the 
 mesentery. These groups are from half an inch to three inches 
 long, of an oval form, and increase in size and number towards the 
 lower part of the ileum. If a group be examined by dissecting 
 away the muscular coat, you find that it is composed of a number 
 of small oval vesicles, like Florence flasks, imbedded in the sub- 
 mucous tissue. They are about three-fourths of a line in diameter, 
 and contain an opaque greyish fluid. No excretory ducts have 
 been traced from these vesicles, but they are supposed to discharge 
 their contents by rupture of their capsules. Between the vesicles 
 are found Lieberkiihn's follicles; and the surface of the patches 
 is covered with villi. These glands are liable to be ulcerated in 
 typhoid fever. 
 
 * A satisfactory examination of the intestinal glands can be made only in specimens 
 quite recent, taken from young persons who haye died suddenly, or from a rapidly 
 fatal disease. 
 
 t J. N. Lieberkiihn, Diss. de fabric, et actione villorum intestin. teuuium, 1782. 
 
 | J. C. Brunn, Gland, duoden. seu pancreas secundarium, 1715. 
 
 Peyer, De glandulis intestinorum, 1682. These glands were first described by 
 Nehemia Grew, in 1681. 
 
 F F 2 
 
436 STRUCTURE OF THE LARGE INTESTINES. 
 
 The solitary glands are scattered in all parts of the small and 
 large intestines. They resemble the glands of Peyer in structure, 
 and only differ from them in being solitary instead of being aggre- 
 gated into groups. 
 
 The principal external characters of the large intes- 
 are > ^ na ^ ^ * s P oucne d or sacculated, and that it 
 has, attached to it, little pendulous portions of fat 
 covered by peritoneum, called ' appendices epiploicce? The 
 pouches (sacculi) are produced by a shortening of the longitudinal 
 muscular fibres, and by their being collected into three bands, 
 about half an inch wide, nearly equidistant from each other. One 
 of these bands corresponds with the attached part of the circum- 
 ference of the bowel ; another with the front part ; a third with 
 its concavity. If at any given part the three bands be divided, 
 the pouches immediately disappear. 
 
 In a colon moderately distended and dried, we observe that the 
 mucous membrane forms numerous ridges or incomplete septa 
 (see fig. 96): they correspond to the grooves on the external 
 surface of the bowel, and disappear, like the sacculi, when the 
 longitudinal bands are divided. 
 
 The rectum differs from the rest of the large intestine in that 
 its longitudinal muscular fibres are not collected into bands, but 
 distributed equally over its whole circumference. Moreover, both 
 the longitudinal and circular fibres are of considerable strength, 
 like those of the oesophagus, as one might expect from the parti- 
 cular functions which these parts of the alimentary canal have to 
 perform. For an inch and a half, or thereabouts, above the 
 anus, the circular fibres are remarkably developed, and constitute 
 the internal ( sphincter aniS 
 
 The mucous membrane of the large intestine differs consider- 
 ably from that of the small. There are no valvulae conniventes or 
 villi ; but the glands of Lieberkiihn and the solitary glands may 
 be seen studding the mucous membrane. The solitary glands are 
 more abundant in the caecum and in the appendix vermiformis 
 than in any other part of the alimentary canal. The blood 
 vessels present the same hexagonal arrangement on the surface as 
 
STRUCTURE OF THE LARGE INTESTINES. 437 
 
 that of the stomach. That the mucous membrane of the large 
 intestine may be temporarily used as a substitute for the stomach, 
 is proved by the fact of persons having been nourished for many 
 weeks, solely by injections. The mucous membrane is lined 
 throughout with columnar epithelium. 
 
 At the junction of the small with the large intestine 
 ^ e mucous membrane is folded so as to form a valve : 
 but it is not a perfect one, as is proved by pouring water 
 into the large intestine, or by the occasional vomiting of injections. 
 
 Fig. 96. 
 
 1. Ileum. 
 
 2. Caecum or caput coli. 
 
 3. Appendix vertniformis 
 
 SECTION THROUGH THE JUNCTION OF THE LARGE AND SMALL INTESTINE TO SHOW THE 
 
 ILIO-CJECAL VALVE. 
 
 The arrangement of the valve is best examined in a dried prepara- 
 tion. The opening is a transverse fissure like a button-hole ; and 
 the two flaps are arranged like an upper and a lower eyelid. The 
 flaps of the valve consist of mucous membrane and the circular 
 fibres of the ileum. The longitudinal fibres of the ileum are con- 
 tinued directly on to the caecum : if these be divided, the ileum 
 can be drawn out, and the valve disappears. 
 
438 DISSECTION OF THE GROIN. 
 
 In many subjects we observe that transverse or 
 Si ds m the oblique folds of the mucous membrane project into 
 
 xGC L Uin. . . 
 
 the rectum. These cannot be seen to advantage unless 
 the bowel be hardened by alcohol in its natural position. Three, 
 more prominent than the rest, and half an inch, or thereabouts, 
 in width, were first pointed out by Mr. Houston.* One projects 
 from the upper part of the rectum, opposite the prostate 
 gland ; another is situated higher up, on the side of the bowel ; 
 while the third is still higher. When thickened or ulcerated, 
 these folds are apt to occasion great pain and obstruction in 
 defalcation. 
 
 THE DISSECTION OF THE THIGH. 
 
 An incision should be made along the groin, from the anterior 
 superior spine of the ileum to the spine of the pubes ; another, 
 from the middle of the first, down the thigh for about six inches. 
 The skin being reflected, the superficial fascia and vessels will be 
 exposed. 
 
 This fascia varies in thickness according to the con- 
 fascia C dition of the body. Like other superficial fascia it is 
 divisible into two layers, between which are situated 
 the inguinal glands, and the cutaneous vessels. The upper layer 
 is continuous with that of the abdomen ; the deeper layer is best 
 marked in the upper part of the thigh, especially where it 
 stretches across the saphenous opening to form the cribriform 
 fascia. 
 
 The cutaneous vessels come from the femoral artery and are 
 three in number, the superficial epigastric, the superficial pudic, 
 and the superficial circumflexa ilii arteries : the first ascends over 
 Poupart's ligament to the abdomen ; the second crosses inwards 
 towards the pubes ; and the third passes outwards to the ileum. 
 Each artery is accompanied by one, sometimes by two veins, 
 which empty themselves, either directly into the femoral, or into 
 the great cutaneous vein of the thigh, called the ' saphena.' 
 
 * Dublin Hospital Reports, vol. v. 
 
DISSECTION OF THE GROIN. 
 
 439 
 
 Su erficial These are easily recognised, by their oval form and 
 inguinal reddish-brown colour. They are divided into two 
 glands. getg . one ^ ^i^ runs parallel to Poupart's ligament, 
 
 and receives the lymphatics from the penis, scrotum, and peri- 
 neum ; the other, which lies along the saphena vein, and transmits 
 
 Fig. 97. 
 
 SUPERFICIAL VESSELS AND GLANDS OF THE GROIN. SAPHENOUS OPENING WITH THE 
 CRIBRIFORM FASCIA. 
 
 1 . Saphenous opening of the fascia lata. 
 
 2. Saphena vein. 
 
 3. Superficial epigastric a. 
 
 4. Superficial circumflexa ilii a. 
 
 5. Superficial pudic a. 
 
 6. External abdominal ring. 
 
 7. Fascia lata of the thigh. 
 
 the lymphatics from the foot and leg. This explains why, in 
 cancer of the scrotum and syphilitic disease of the penis, the first 
 set becomes enlarged ; and the second in diseases of the lower ex- 
 tremity. The absorbent vessels which pass to and from the glands 
 are small, and easily escape observation, unless specially sought. 
 
440 DISSECTION OF THE GROIN. 
 
 They all pass through the femoral ring into the abdomen, and 
 eventually empty themselves into the thoracic duct. 
 
 The glands mentioned in the preceding paragraph are all super- 
 ficial. There are others, more deeply seated, close to the great 
 vessels of the thigh : these are much smaller, and sometimes 
 cannot be found. 
 
 The superficial epigastric artery comes out through the fascia 
 lata, half an inch below Poupart's ligament, and supplies the 
 inguinal glands. Its further course is described at p. 309. 
 
 The superficial circumflexa ilii runs parallel to Poupart's liga- 
 ment towards the crest of the ileum, and ends in the skin arid 
 subcutaneous tissue. 
 
 The superficial external pudic comes out through the sa- 
 phenous opening, crosses over the spermatic cord, and supplies the 
 penis and scrotum in the male, and the labium in the female. 
 This artery is liable to be divided in the operation for femoral 
 hernia ; also in that for phirnosis, since it runs along the penis to 
 supply the prepuce. Arising, as they all do, directly from so large 
 an artery as the femoral, they sometimes bleed profusely ; for it is 
 an admitted fact, that when even a small branch, coming directly 
 from a principal artery, is divided near its origin, it will sometimes 
 pour out as much blood as if an opening were punched out of the 
 trunk as large as the area of the divided branches.* There is 
 another pudic artery, called the deep or inferior external pudic : 
 this runs between the fascia lata and the pectineus, supplying 
 that muscle, the scrotum in the male, and the labium in the 
 female. 
 
 The incision should be prolonged down the thigh, over the knee 
 to the tubercle of the tibia. The skin must then be reflected, to 
 expose the subcutaneous tissue over the whole of tbe front of the 
 thigh. In it will be found the cutaneous vessels and nerves, 
 which must be carefully dissected. 
 
 * Mr. Listen had occasion to tie the external iliac artery for a supposed injury (by 
 a pistol-ball) to the femoral. It was discovered, after the death of the patient, that 
 the ball had injured only one of the superficial branches of the femoral, about an inch 
 from its origin. See his paper in the Med.-Chir. Trans, vol. xxix. 1846. 
 
DISSECTION OF THE GROIN. 441 
 
 This is the chief subcutaneous vein of the lower 
 vein 6na limb. Its roots, arising on the inner side of the foot, 
 unite into a single trunk, which ascends over the inner 
 ankle, along the inner side of the leg behind the knee, along the 
 inner and front part of the thigh, where it passes through an 
 opening the ' saphenous opening 'in the fascia lata, to join the 
 femoral vein, immediately below the crural arch (fig. 97). In 
 this long course it receives several tributary veins, some of which 
 are often large; and, just before its termination, it is joined by 
 the superficial veins of the groin already alluded to. Like all 
 subcutaneous veins, it is provided at intervals with valves to 
 support the column of the blood. 
 
 The distribution of the cutaneous nerves of the thigh 
 var i es considerably ; so that a general description of 
 their usual arrangement is sufficient. The cutaneous 
 nerves are divided, according to their situation, into external, 
 middle, and internal. All directly or indirectly proceed from the 
 lumbar plexus, and are seen coming through the fascia, and 
 dividing in the subcutaneous tissue. 
 
 a. The external cutaneous nerve is a branch of the second 
 lumbar nerve. It enters the thigh beneath Poupart's ligament 
 close to the anterior superior spine of the ileum. Here it divides 
 into two branches, an anterior and a posterior. The anterior 
 division runs down at first in a sheath of the fascia lata : it then 
 comes through it, and can be traced down the outer side of the 
 thigh as far as the knee, giving off numerous cutaneous branches. 
 The posterior branch, after coming through the fascia, divides into 
 branches, which are distributed to the skin over the nates and the 
 posterior part of the thigh. 
 
 b. The middle cutaneous nerves, two or more in number, are 
 derived from the anterior crural, which itself is a branch of the 
 lumbar plexus. They pierce the sartorius four or five inches below 
 the crural arch, and descend along the front of the thigh to the 
 knee, distributing branches on either side (see diag., p. 453). 
 
 b. The internal cutaneous nerves, two or more, also branches 
 of the anterior crural, perforate the fascia lata, one about the 
 
442 DISSECTION OF THE GROIN. 
 
 middle,* another about the lower third of the thigh, and supply 
 the skin on the inner side. The last-named branch communicates 
 with branches from the obturator, and sometimes with the saphe- 
 nous, about the middle of the thigh, and again with the latter a 
 little above the knee. 
 
 d. The crural branch of the genito-crural nerve must be 
 sought for carefully below Poupart's ligament: it perforates the 
 fascia external to the femoral artery, and supplies the skin in front 
 of the thigh. About two or three inches below the crural arch 
 it usually communicates with the middle cutaneous nerve. 
 
 e. The ilio-inguinal nerve, after emerging from the external 
 abdominal ring, supplies the skin on the inner aspect of the 
 thigh. 
 
 Fascia lata Remove the subcutaneous structure to examine the 
 or muscular muscular fascia, or ' fascia lata ' of the thigh. The 
 fascia. purpose of this fascia is to cover the muscles of the 
 
 thigh collectively, and to form separate sheaths for each ; so that 
 it not only packs them together, but maintains each in its proper 
 position. A knowledge of these sheaths is important, because 
 they interfere with the progress of deep-seated matter towards 
 the surface, and cause it to burrow in this or that direction ac- 
 cording to the part in which it forms. 
 
 The fascia is not of equal strength all round the thigh. It is 
 comparatively thin and transparent on the inner side ; exceedingly 
 thick and strong down the outer side : here, indeed, it has the 
 appearance of a dense expanded tendon, strapping down the vastus 
 externus muscle ; and it certainly performs the office of a tendon, 
 for it gives insertion to two powerful muscles namely, the tensor 
 fasciae femoris, and the glutseus maximus (fig. 98). 
 
 The fascia lata is attached to the margin of the bones which 
 constitute the framework of the lower extremity. Beginning from 
 above, its attachment can be traced along the crest of the ileum, 
 thence along the crural arch to the body of the pubes, and down 
 
 * It is important to note that one, or sometimes two, of these internal cutaneous 
 nerves cross the sheath of the femoral artery just where the sartorius begins to over- 
 lap it ; and therefore at the spot where it is usually tied. See diag., p. 453. 
 
DISSECTION OF THE GROIN. 
 
 443 
 
 Fig. 98. 
 
 the rami of the pubes and ischiurn. Proceeding down the thigh, 
 
 it penetrates, on either side of the limb, to the linea aspera, 
 
 forming what are called the ' inter muscular 
 
 septa,' which separate the extensor from the 
 
 flexor muscles. Below, it can be traced all round 
 
 the knee-joint, and is particularly strong, es- 
 pecially on the outer side, where it is attached 
 
 to the head of the tibia and fibula. 
 
 There are numerous small apertures in the 
 
 fascia, through which the cutaneous nerves and 
 
 vessels are transmitted ; and one large opening 
 
 the f saphenous opening* through which the 
 
 saphena vein passes to join the femoral. That 
 
 part of the fascia lata situated external to the 
 
 saphenous opening is termed the iliac portion 
 
 of the fascia lata ; that internal to it, the pubic 
 
 portion. 
 
 The saphenous opening is an oval 
 aperture in the fascia lata, situated 
 immediately below the crural arch, on 
 the inner side of the front aspect of 
 
 the thigh. There is no definite edge to the 
 
 saphenous opening until the fascia, which covers 
 
 the opening and blends with its margin, has 
 
 been removed.* The term cribriform ' has been 
 
 given to this fascia, because it is riddled with ^ Tensor fascie femor ^ 
 
 holes for the passage of the superficial vessels |- S^rerfibre^dftto 
 
 and absorbents. It is a thin covering over the 4 - Fascia lata - 
 
 saphenous opening, and is prolonged from the outer edge of the 
 opening over the sheath of the femoral vessels, and 
 adheres on the inner side to the fascia lata, over the 
 pectineus muscle. Some anatomists describe this fascia 
 
 as a portion of the ' superficial fascia ; ' others consider it as a 
 
 Saphenous 
 opening in 
 the fascia 
 lata. 
 
 Cribriform 
 fascia. 
 
 * According to Mr. Callender, a natural saphenous opening does sometimes exist, in 
 consequence of the cribriform fascia becoming atrophied. On the Anatomy of the parts 
 concerned in Femoral Rupture, 1862. 
 
444 
 
 DISSECTION OF THE GROIN. 
 
 thin prolongation of the fascia lata itself across the opening. Its 
 chief surgical importance is derived from the fact that it forms 
 one of the coverings of a femoral hernia. 
 
 The cribriform fascia must now be removed so as to display the 
 saphenous opening, which will appear as represented in fig. 99. 
 
 Eeverting to the saphenous opening, we observe that it is situ- 
 ated just below the crural arch, not far from the pubes; that it is 
 
 Fig. 99. 
 
 1. Crural arch. 
 
 2. Saphenous opening of 
 
 the fascia lata. 
 
 3. Saphena vein. 
 
 4. Femoral vein. 
 
 5. Gimbernat's ligament. 
 
 6. External ring. 
 
 7. Position of the internal 
 
 ring. 
 
 DIAGRAM OF THE FEMORAL UINO. 
 
 (The arrow is introduced into the femoral ring.) 
 
 oval with the long axis vertical, and about one and a half or two 
 inches long. Its border on the inner or pubic side is not denned ; 
 for here the fascia lata ascends under the femoral vessels, and is 
 continuous with the iliac fascia of the pelvis.* But the outer or 
 iliac border is defined clearly enough. This lies in front of the 
 femoral vessels, is crescent-shaped, with the concavity towards the 
 pubes, and called the falciform process of ' Burns.' The lower 
 horn of the crescent curves under the saphena vein, and is lost in 
 the fascia on the inner side of the opening. The upper horn 
 
 * On the inner side of the femoral vessels the pubic portion of the fascia is attached 
 to the linea ilio-pectinea. 
 
PARTS CONCERNED IN FEMORAL HERNIA. 445 
 
 (Key's ligament)* arches over the femoral vein, and is continued 
 uninterruptedly into ' Grimbernat's ligament ' or into that part of 
 the crural arch which is inserted into the linea ilio-pectinea. The 
 upper horn deserves especial attention, because it forms the upper 
 boundary of the aperture through which a femoral hernia takes 
 place ; and, being chiefly concerned in the constriction of the 
 rupture, must be divided for its relief. This may be easily 
 ascertained by introducing the little finger under the crural arch, 
 on the inner side of the femoral vein in other words into the 
 femoral ring (see the arrow in the diagram). Feel how much 
 the upper horn of the crescent would girt the neck of a hernia, 
 and that its tension is greatly influenced by the position of the 
 lirnb ; for if the thigh be bent and brought over to the other 
 side, the tension of all the parts is materially lessened.f 
 
 ANATOMY OF THE PAETS CONCEKNED IN FEMORAL HERNIA. 
 
 The anatomy of the parts concerned in femoral hernia cannot be 
 thoroughly understood without the assistance of special dissec- 
 tions. The following demonstration, therefore, takes for granted 
 that the student has the opportunity of seeing the parts, not only 
 on their femoral, but also on their abdominal side. 
 
 We propose to treat the different parts of the subject in the 
 following order : 
 
 a. The formation of the crural arch. 
 
 6. The arrangement of the parts which pass under the arch. 
 
 c. The sheath of the femoral vessels. 
 
 d. The crural canal and ring. 
 
 e. The practical application of the subject. 
 
 * This upper horn is sometimes called ' Key's ligament,' after the surgeon who 
 first drew attention to it : Observations in Surgery, by "W. Hey, F.R.S. London, 
 1810. 
 
 f We must always bear in mind, that though the crural arch and the fascia attached 
 to it have received particular names, they are not, on that account, distinct and se- 
 parate ; but all are intimately connected, and portions merely of one continuous expan- 
 sion. Thus all the parts are kept in a condition of mutual tension, which depends 
 very much on the position of the thigh. 
 
446 PARTS CONCERNED IN FEMORAL HERNIA. 
 
 Crural arch ^ke l wer border of the aponeurosis of the external 
 orPoupart's oblique muscle extends from the anterior superior spine 
 ligament. Q f ^ Q i} eum to the spine of the pubes, and forms, over 
 the bony excavation beneath, what is called the ' crural arch ' or 
 * Poupart's ligament.' (It is marked by the dark line in fig. 100.) 
 The direction of the arch is at first somewhat oblique, but towards 
 its inner half, becomes nearly horizontal. In consequence of its 
 intimate connection with the muscular fascia of the thigh, the line 
 of the arch describes a gentle curve with the convexity downwards. 
 The arch is attached to the spine of the pubes, and also for some 
 distance along the linea ilio-pectinea (fig. 100). This additional 
 attachment, called, after its discoverer, GimbernaVs ligament* is 
 of importance, for it is most frequently the seat of stricture in 
 femoral hernia. 
 
 The best view of Gimbernat's ligament is obtained 
 from wittim tne abdomen, it being only necessary to 
 remove the peritoneum. It is placed nearly horizon- 
 tally, in the erect posture, and is triangular with its apex at the 
 pubes and its base directed outwards. In front, it is continuous 
 with the crural arch ; behind, it is inserted into the linea ilio- 
 pectinea ; externally, it is continuous with the fascia lata (fig. 99). 
 Its length is from |ths of an inch to 1 inch ; but it varies in different 
 subjects, and is usually longer in the male than the female : this is one 
 among many reasons why femoral hernia is less frequent in the male. 
 On putting your finger into the femoral ring, you feel the sharp 
 and wiry edge of this ligament : observe, too, that as the body lies 
 on the table, the plane of the ligament is perpendicular, and 
 therefore that it recedes from the surface. 
 
 The crural arch transmits from the abdomen into 
 oVthe^art? *^ e thigh (proceeding in order from the outer side) 
 which pass the following objects, shown in fig. 100: 1. The ex- 
 "rch 6rthe ternal cutaneous nerve; 2. The iliacus and psoas 
 muscles, with the anterior crural nerve between them ; 
 3. The femoral artery and vein with the crural branch of the 
 
 * Don Antonio de Gimbernat was a Spanish surgeon, who published, in 1793, A 
 new Method of Operating for the Femoral Hernia. Madrid. 
 
PARTS CONCERNED IN FEMORAL HERNIA. 447 
 
 genito- crural nerve. These muscles and vessels fill up the space 
 beneath the crural arch, except on the inner side of the femoral 
 vein, where a comparatively vacant space is left for the passage of 
 the absorbents : this is called the crural canal. The muscles are 
 separated from the vessels by a strong vertical fibrous partition 
 passing from the arch to the bone, which is nothing more than a 
 continuation of the sheath of the psoas. The artery, too, is sepa- 
 rated from the vein by a similar, although a much weaker parti- 
 
 Fig. 100 
 
 External cutaneous n 
 
 Crural arch. 
 
 Femoral ring. 
 
 Femoral vein and artery. 
 
 POSITION OF PARTS UNDER THE CRTJRAJL ARCH (VERTICAL SECTION 1 ). 
 
 tion, and there is a third close to the inner side of the vein. These 
 three partitions not only keep all the parts in their right place, but 
 confine the arch down to the bone, and prevent its being uplifted 
 by any protrusion between it and the muscles and vessels. This, 
 coupled with the close attachment of the iliac fascia to the crural 
 arch, explains why a femoral hernia rarely takes place in any other 
 situation than on the inner side of the femoral vein.* 
 
 * If the partitions from any cause yield, or become slack, then a rupture may de- 
 scend in front of the vessels, or even (though this is rare) on the outer side of the 
 artery. 
 
448 
 
 TARTS CONCERNED IN FEMORAL HERNIA. 
 
 Sheath of ^ emora ^ vessels do not descend uncovered beneath 
 
 the femoral the crural arch, but come down inclosed in a mem- 
 branous sheath. This sheath appears to be derived im- 
 mediately from the arch itself, but it is really formed, in front, by 
 a prolongation from the fascia transversalis of the abdomen. This 
 prolongation, uniting with the continuation from the iliac fascia 
 to join the fascia lata behind the femoral vessels, forms a funnel, 
 with the wide part uppermost, into which the femoral vessels enter. 
 
 Fig. 101. 
 
 1,1. Fascia transver- 
 salis. 
 
 2. Internal ring. 
 
 3. Crural arch re- 
 
 flected. 
 
 4. Sheath of the fe- 
 
 moral vessels. 
 
 5. Saphena vein. 
 
 DIAGRAM OF THE SHEATH OF THE FEMORAL VESSELS. 
 
 This is what is described as the funnel-shaped sheath of the femoral 
 vessels. 
 
 To examine this sheath satisfactorily, it is necessary to reflect, 
 from its attachment to the crural arch, the upper horn of the 
 saphenous opening, as shown in fig. 101. By this proceeding, you 
 expose the fascia transversalis coming down over the femoral vessels, 
 and forming the front part of their sheath. The hind part of the 
 sheath is formed by the fascia iliaca, which runs down behind the 
 vessels to join the pubic portion of the fascia lata. The sheath 
 descends about as low as the lower horn of the saphenous opening, 
 
PARTS CONCERNED IN FEMORAL HERNIA. 449 
 
 where it is gradually lost upon the proper investment of the femoral 
 vessels. The outer part of the sheath is perforated by the crural 
 branch of the genito-crural nerve, and the superficial arteries of the 
 groin ; the inner part by the saphena vein and some absorbent 
 vessels. 
 
 Within the sheath of the femoral vessels, are three compartments 
 separated from each other by partitions : the outer one is occupied 
 by the femoral artery ; the middle, by the femoral vein ; the 
 inner is the crural canal, into which the femoral hernia descends. 
 Practically, the sheath is important for many reasons : 
 1. A femoral hernia descends inside it. 2. It forms, therefore, 
 one of the coverings (fascia propria) of the hernia. 3. It contains 
 in its substance bands of fibres (deep crural arch) running in the 
 same direction as the crural arch, but quite independent of it, as 
 shown in fig. 101 ; these bands lie over the neck of the sac, and are 
 often the seat of the stricture ; it is therefore necessary to divide 
 them before the intestine can be returned. 
 
 Crural canal ^e ^^ ow un der the crural arch is completely occu- 
 and femoral pied except for a small space, called the crural canal, 
 nn * on the inner side of the vein. This canal is from a 
 
 quarter to half an inch in length. It commences, above, in the 
 femoral ring ; and ends, below, at the saphenous opening. The 
 femoral ring is the upper opening of the crural canal, and is 
 bounded, in front, by the crural arch ; behind, by the bone ; on 
 the outer side, by the femoral vein ; on the inner side, by the thin, 
 wiry edge of GKmbernat's ligament. In the undisturbed condition 
 of the parts there is no gap ; it is only a weak place, which, when 
 a hernia escapes through it, feels like a ring : hence the name of 
 ' femoral ring.'* 
 
 The femoral ring is surrounded on all sides by unyielding struc- 
 tures. This accounts for the little benefit afforded by the warm 
 bath in cases of strangulation. Mr. Lawrence was in the habit of 
 
 * The femoral ring is naturally occupied by a little fat and cellular membrane, by 
 absorbent vessels, and often by a small absorbent gland. But \ve have never met with 
 anything deserving the name of a 'diaphragm' or membranous septum, such as is 
 described by Cloquet as the ' septum crurale.' 
 
 G G 
 
450 PARTS CONCERNED IN FEMORAL HERNIA. 
 
 saying that he never saw a strangulated femoral hernia where the 
 warm bath was of any avail. 
 
 Practical ap- From what has been said, the student ought now to 
 plication of understand 1, at what point a femoral hernia escapes 
 the subject. from the a bdomen ; 2, the course which it takes, and 
 its relations to the surrounding parts ; 3, the proper mode of at- 
 tempting the reduction ; 4, the structure and arrangement of its 
 coverings ; and, lastly, the probable seat of stricture. 
 
 The hernia escapes from the abdomen through the femoral ring 
 that is, under the weak part of the crural arch, between the 
 femoral vein and Grimbernat's ligament. Here is the mouth of the 
 hernial sac, or that part of it which communicates with the abdo- 
 men. It descends for a short distance nearly perpendicularly, and 
 projects as a small tumour in front of the pectineus muscle. Its 
 progress downwards, however, is soon arrested, partly by the very 
 close adhesion of the subcutaneous structures to the lower margin 
 of the saphenous opening; partly by flexion of the thigh. Con- 
 sequently, if the hernia increase in size, it must rise over the crural 
 arch, where the subcutaneous tissue offers less resistance ; and the 
 bulk of the hernia extends outwards towards the ilium, assuming 
 more or less of an oblong form, with the long axis parallel to the 
 crural arch. Since, then, the body of the hernia forms a very acute 
 angle with the neck, the right mode of attempting its reduction is, 
 to draw it first down from the groin, and then to make pressure on 
 it backwards in the direction of the femoral ring. 
 Coverings of ^e Cover ^ n 9 s f a femoral hernia are as follow : 
 a femoral It first protrudes before it the peritoneum, technically 
 jcalled the hernial sac.* The sac is covered by more or 
 less fat, according to the condition of the patient, called the sub- 
 peritoneal fat. It next pushes before it the sheath of the femoral 
 vessels, which forms an investment called the ' fascia propria. 1 
 In front of this is the cribriform fascia. Lastly, there is the 
 subcutaneous tissue and skin. 
 
 The seat . of stricture is usually at the femoral ring, and the 
 
 * In some cases the fascia propria so much resembles the hernial sac, that it is not 
 easy to distinguish between them. Generally speaking they are separated by a small 
 quantity of fat. 
 
PARTS CONCERNED IN FEMORAL HERNIA. 451 
 
 position of the neighbouring blood vessels indicates that the proper 
 direction in which to divide the stricture is, either directly inwards, 
 through Gimbernat's ligament, as recommended by Mr. Lawrence, 
 or upwards through Hey's ligament, as recommended by Sir A. 
 Cooper.* There is no risk of wounding an artery, supposing the 
 vessels to take their ordinary course. But it occasionally happens 
 (as observed p. 388), that the obturator artery runs above (in the re- 
 cumbent position) the femoral ring ; in such a case, the neck of the 
 sac would be encircled by a large blood vessel. f From the exami- 
 nation of two hundred bodies, the chances are about seventy to one 
 against this unfavourable distribution. But the possibility of it 
 has given rise to this rule in practice not to cut deeply in any 
 one place through the stricture, but rather to notch it in several. 
 By this proceeding we are much less likely to wound the abnormal 
 artery, because it does not run at the base of Gimbernat's liga- 
 ment, but about a line and a half from the margin of it.J 
 
 Such is an outline of the anatomy of the parts concerned in a 
 femoral hernia, The normal anatomy in each case being nearly 
 the same, it might be supposed that all operations for the relief of 
 this kind of hernia would be straightforward and pretty much 
 alike ; but this is very far from being the case : indeed, surgeons 
 agree that they never take the knife in hand without the ex- 
 pectation of meeting some peculiarity. 
 
 The fascia must now be removed from the front of the thigh, 
 without disturbing the subjacent muscles from their relative 
 positions. The mass of muscles, on the inner side of the thigh, 
 
 * The operation recommended by Sir A. Cooper is that usually performed now ; 
 because, if Gimbernat's ligament be divided, its cut edges often retract to such an ex- 
 tent, that no truss can possibly retain the hernia when the patient assumes the erect 
 posture. 
 
 t The museum of St. Bartholomew's Hospital contains two examples of double fe- 
 moral hernia in the male, with the obturator arising on each side from the epigastric. 
 In three out of the four hernise the obturator runs on the inner side of the mouth of 
 the sac. See Prep. 55, 69, Series 17. 
 
 + During the session of 1867-68 more than half a dozen instances occurred where 
 the obturator artery was given off by a common origin with the epigastric artery. In 
 all these cases, however, the artery passed close by the bone, so that it would not have 
 been injured in the operation for relief of strangulation. 
 
 GG 2 
 
452 SCARPA'S TRIANGLE. 
 
 consists of the adductors ; that in the middle, of the extensors : 
 the long thin muscle crossing obliquely in front from the outer to 
 the inner side, is the sartorius. In the middle are seen the 
 femoral vessels, and the anterior crural nerve emerging beneath 
 the crural arch. 
 
 This muscle arises from the anterior superior spine 
 of the ileum, and from the ridge below to the extent of 
 an inch. It passes obliquely like a strap over the front of the 
 thigh towards the inner side ; and then descends almost perpen- 
 dicularly on the inner side of the thigh as far as the knee, where it 
 terminates in a flat tendon which expands, and is inserted into 
 the inner and front part of the tibia just below its tubercle. 
 The tendon appears all the wider on account of its broad con- 
 nection with the fascia of the leg. A large bursa * is interposed 
 between the tendon and the internal lateral ligament. The chief 
 action of the muscle is to fix the pelvis steadily on the thigh. It 
 also crosses one leg over the other, as tailors sit when at work.f 
 Its nerve comes from the middle cutaneous branch of the anterior 
 crural. 
 
 In consequence of the oblique direction of the 
 sartorius, a triangle is formed, which has this muscle 
 and the adductor longus for its two sides, and the 
 crural arch for its base : the triangle is called c Scarpa's.' J The 
 contents of this important space should be carefully displayed, and 
 their relative positions well studied. This triangle contains all the 
 parts which pass under the crural arch ; namely, from without 
 inwards ; the external cutaneous nerve, close to the anterior spine 
 of the ileum ; the iliacus internus and psoas ; the anterior crural 
 .nerve and its divisions, especially the long saphenous nerve ; the 
 femoral artery with its great branch ' the profunda,' which runs 
 
 * In persons, females especially, who are in the habit of riding, this bursa some- 
 times becomes enlarged. 
 
 f Hence the name given to it by Spigelius (De corporis hum. fabric.), ' Quern ego 
 sartorium musculum vocare soleo, quod sartores eo maxime utuntur, dum cms cruri 
 inter consuendum imponunt.' 
 
 J So called in compliment to the Italian anatomist who first tied the femoral in it 
 for popliteal aneurism. 
 
SCARPA'S TRIANGLE. 
 
 453 
 
 down behind it and gives off the ( internal' and ( external circum- 
 flex ;' the femoral vein, joined by the profunda vein and the 
 internal saphena ; and, lastly, the pectineus muscle. 
 
 The triangle is important in a surgical point of view, since it is 
 in this space that the femoral artery is usually ligatured for popli- 
 teal aneurism. The guide to the artery is the inner border of the 
 sartorius. The situation at which this muscle crosses over the 
 
 Fig. 102. 
 
 1. Sartorius. 
 
 2. Adductor longus. 
 
 3. External cutaneous 
 
 n. 
 
 4. Iliacus internus. 
 
 5. Anterior crural n. 
 
 6. Femoral artery. 
 
 7. Femoral vein. 
 
 8. Pectineus. 
 
 9. Long saphenous n. 
 
 10. Internal cutaneous 
 
 n. 
 
 11. Nerve to vastus in- 
 
 ternus. 
 
 12. Middle cutaneous n. 
 
 DIAGRAM OF SCARPA S TRIANGLE. 
 
 femoral artery, varies from one and a half to four and a half inches 
 below Poupart's ligament ; so that no rule can be laid down as to 
 the exact situation where the artery disappears under the sartorius. 
 The best way to find the inner border of the muscle daring life, is 
 to make the patient put it into action. 
 
 A strong group of muscles, called the ' adductors,' 
 
 muscles 01 extends along the inner side of the thigh, from the 
 
 pelvis to the femur. Their two most important actions 
 
454 FRONT OF THE THIGH. 
 
 are to co-operate in balancing the pelvis steadily on the thigh, as in 
 standing on one leg ; and (if the fixed point be reversed) to draw 
 together or adduct the thighs. They are five in number, and are 
 supplied, with one exception the pectineus by the same nerve 
 namely, the obturator. They are termed, respectively, the gracilis, 
 adductor longus, pectineus, adductor brevis, and adductor magnus. 
 The innermost is the gracilis ; to clean it properly, it should be 
 stretched by separating one thigh from the other. 
 Gra This long, flat muscle arises by a broad, ribbon-like 
 
 tendon from the pubes close to the symphysis, and from 
 the border of the pubic arch nearly as low as the tuber ischii. It 
 descends almost perpendicularly on the inner side of the thigh, 
 and terminates in a tendon which subsequently spreads out, and 
 is inserted into the inner side of the tibia below the tubercle, im- 
 mediately behind the sartorius. Both tendons play over the 
 internal lateral ligament of the knee-joint, and there is a bursa 
 common to both. This muscle assists in fixing the pelvis, and in 
 adducting the thigh ; it also helps to bend the knee. Its nerve 
 comes from the anterior division of the obturator. 
 
 This muscle lies external to the gracilis, and arises 
 Adductor ^ r0 und tendon from the front of the pubes below 
 
 longus. -3pS! J 
 
 c ' the crest. As it descends, it becomes broader, and is 
 inserted into the middle third of the linea aspera of the femur. It 
 forms with the sartorius a triangular space called Scarpa's triangle 
 (p. 452). It is supplied by the anterior division of the obturator 
 nerve. 
 
 This muscle lies on the same plane, but external to 
 ius< the adductor longus. It arises from the triangular 
 surface of the pubes in front of the linea ilio-pectinea, and is 
 inserted into the ridge leading from the lesser trochanter to the 
 linea aspera. Its nerve comes from the anterior crural, sometimes 
 also from the obturator (p. 358). 
 
 By separating the contiguous borders of the pectineus and the 
 adductor longus, the adductor brevis is exposed with the anterior 
 division of the obturator nerve lying upon it. To obtain a com- 
 plete view of them, the pectineus and adductor longus must be 
 
FRONT OF THE THIGH. 455 
 
 reflected from their origin. The obturator nerve supplies all the 
 adductors. It leaves the pelvis through the upper part of the 
 obturator foramen, and soon divides into an anterior and posterior 
 branch : the anterior runs in front of the adductor brevis, and 
 supplies the hip-joint, the adductor longus, the gracilis, and some- 
 times the adductor brevis ; the posterior runs behind the adductor 
 brevis, and supplies it as well as the obturator externus, the 
 adductor magnus, and the knee-joint. 
 
 This muscle arises from the front surface of the 
 P u ^ es near the symphysis, and from its ascending 
 ramus ; it widens as it descends, and is inserted into 
 the upper third of the linea aspera. Its nerve is derived from the 
 obturator. By reflecting it from its origin, the following muscle is 
 exposed.*" 
 
 This muscle arises from the lower two-thirds of the 
 P ll ki c arcn an d from the tuberosity of the ischium. Its 
 fibres spread out, and are inserted, behind the other 
 adductors, into the whole length of the linea aspera ; also into the 
 ridge leading from it to the inner condyle. Its nerve comes from 
 the posterior division of the obturator. Observe that all the ad- 
 ductor muscles are inserted into the femur by fiat tendons which 
 are more or less connected with each other. 
 
 About the junction of the upper two-thirds with the lower third 
 of the thigh, the femoral artery passes through an oval opening in 
 the tendon of the adductor magnus. 
 
 Psoas magnus and These muscles have been fully described in the 
 iliacus internus. dissection O f the abdomen (p. 348). 
 
 This muscle is situated at the upper and outer part 
 
 the thi S h ' Jt arises fromthe external lip of the 
 crest of the ileum, close to the anterior spine, descends 
 with a slight inclination backwards, and is inserted, at the junction 
 of the upper with the middle third, between two layers of the strong 
 aponeurosis, generally described as part of the fascia lata (p. 443). 
 
 * Beneath the adductor brevis, and running parallel with the upper border of the 
 adductor magnus, is seen the obturator externus. But the description of this muscle is 
 deferred till the dissection of the external rotators of the thigh. 
 
456 FRONT OF THE THIGH. 
 
 Its chief use is to fix the pelvis steadily on the thigh, and also to 
 rotate the thigh inwards ; in this last action it co-operates with the 
 anterior fibres of the glutseus medius, with which it is almost in- 
 separably connected. Any one may convince himself of this by 
 placing the hand on the hip, and rotating the thigh inwards. 
 Both these muscles are supplied by the same nerve the superior 
 glutseal. 
 
 To form an adequate idea of the strength, extent, and connec- 
 tions of the aponeurosis on the outer side of the thigh, it should be 
 separated from the vastus externus muscle upon which it lies. 
 There is no difficulty in doing so, for it is united to the muscle by 
 an abundance of loose cellular tissue.* With a little perseverance 
 the aponeurosis can be traced to the linea aspera, the head of the 
 tibia, and the fibula. See how completely it protects the outer side 
 of the knee-joint. 
 
 The powerful muscles situated between the tensor 
 fasciae on the outer and the adductors on the inner 
 side, are extensors of the leg. One of them the 
 * rectus ' arises from the pelvis ; the other the ' triceps ' arises 
 from the shaft of the thigh bone by three portions, called, respec- 
 tively, the cruraeus, the vastus internus and externus. All are 
 supplied by the anterior crural nerve. 
 
 To see the origins of the rectus femoris, dissect between the 
 origin of the sartorius and the tensor fasciae; in doing so, avoid 
 injuring the branches of the external circumflex artery. 
 
 This muscle arises from the pelvis by two strong 
 tendons, which soon unite at an acute angle : one from 
 the anterior inferior spine of the ileum, the other from the rough 
 surface of the ileum, just above the acetabulum. The muscle 
 descends perpendicularly down the front of the thigh, and is 
 inserted into the common extensor tendon. The structure of this 
 muscle is remarkable. A tendon runs down the centre, and the 
 muscular fibres are implanted on either side of it, like the vane on 
 the shaft of a feather. Its nerve comes from the anterior crural. 
 
 * When this tissue becomes the seat of suppuration, the matter is apt to extend all 
 down the outside of the thigh, not being able to make its way to the surface by reason 
 of the dense fascia. 
 
 
FRONT OF THE THIGH. 457 
 
 This mass of muscle surrounds the greater part of 
 ~ the shaft of the femur 5 therefore the whole extent of it 
 cannot be seen without completely dissecting the thigh. 
 It consists of an outer, middle, and inner portion, called, respec- 
 tively, the vastus externus, the crurseus, and the vastus internus. 
 The vastus externus arises by a very strong aponeurosis from the 
 outer side of the base of the great trochanter, and from the outer 
 lip of the linea aspera nearly down to the external condyle. The 
 crurceus arises from the upper three-fourths of the front surface of 
 the shaft. The vastus internus arises from the upper two-thirds 
 of the inner surface of the shaft, and also from the inner lip of the 
 linea aspera. They are all supplied by branches from the anterior 
 crural nerve. 
 
 Common ^ ie ten don of the rectus, gradually expanding, be- 
 
 extensor comes connected on its under surface with the tendon 
 of the cruneus,* and on either side with that of the 
 vasti, and is firmly fixed into the upper part and sides of the 
 patella. From this bone the common extensor tendon, the ( liga- 
 mentum patellce,' descends over the front of the knee-joint, and is 
 inserted into the tubercle of the tibia. Besides this, the lower 
 fibres of the vasti terminate on a sheet-like tendon, which runs 
 wide of the patella on either side, and is directly inserted into the 
 sides of the head of the tibia and fibula, so that the knee is com- 
 pletely protected all round. The patella is a great sesamoid bone, 
 interposed to facilitate the play of the tendon over the condyles of 
 the femur : it not only materially protects the joint, but adds to 
 the power of the extensor muscles, by increasing the angle at which 
 the tendon is inserted into the tibia. 
 
 To facilitate the play of the extensor tendon there are two bursas. 
 One is placed between the ligamentum patellae and the tubercle of 
 
 * A few of the deeper fibres of the crurseus are inserted into the fold of the synovial 
 membrane of the knee-joint which rises above the patella. These are described as a 
 distinct muscle, under the name of the ' sub-crur&us.' Their use is to raise the 
 synovial membrane, so that it may not be injured by the play of the patella. Since 
 the triceps is connected to the lower part of the shaft of the femur only by loose cel- 
 lular tissue, there is nothing to prevent the distention of the synovial membrane, in 
 cases of inflammation, to the extent of several inches above the patella. 
 
458 FRONT OF THE THIGH. 
 
 the tibia, the other between the crurseus and the lower part of the 
 femur. This last is of considerable size. In early life it is, as a 
 rule, distinct from the synovial membrane of the knee-joint; but 
 after a few years of friction a wide communication frequently exists 
 between them. 
 
 Action of ^^ e ex ^ ensor niuscles of the thigh are among the 
 
 the extensor most powerful in the body. Great power of extending 
 muscles. ^ Q knee is one of the essential conditions of the erect 
 attitude. Without it, how could we rise from the sitting position? 
 When erect, how could we walk, run, or spring ? The rectus, by 
 taking origin from the pelvis, gains a double advantage ; it acts 
 upon two joints simultaneously, bending the thigh while it extends 
 the knee, as when we advance the leg in walking : it also contri- 
 butes to balance the pelvis on the head of the thigh bone, and thus 
 prevents the body from falling backwards. We cannot have a 
 better proof of the collective power of the extensor muscles than 
 when the patella is broken by their contraction ; an inj ury which 
 sometimes happens when a man, slipping backwards, makes a 
 violent effort to recover his balance. 
 
 The skin over the patella is exceedingly loose, and 
 ^ n ^ ne subcutaneous tissue is a bursa of considerable 
 size. Since this bursa is apt to enlarge and inflame in 
 females who are in the habit of kneeling at their work, it is gene- 
 rally called 'the housemaid's bursa.' The bursa is not seated 
 exactly over the patella, but extends some way down the liga- 
 mentum patellas ; indeed, in some cases it is entirely confined 
 to this ligament. This corresponds with the position of the tu- 
 mour which the bursa occasions when enlarged. Generally speak- 
 ing, in subjects brought for dissection, the wall of the bursa is 
 more or less thickened, and its interior intersected by numerous 
 fibrous cords, remnants of the original cellular structure altered 
 by long-continued friction. Again, the wall of the bursa does 
 not always form a complete sac ; sometimes there is a wide 
 opening in it ; this explains the rapidity with which inflammation, 
 in some cases, extends from the bursa into the surrounding cellular 
 tissue. 
 
FRONT OF THE THIGH. 459 
 
 Below the bursa is a layer of fascia lata, and under this is a 
 network of arteries. The immediate covering of the bone, or 
 what may be called its periosteum, is a strong expansion derived 
 from the extensor tendon. This is interesting for the following 
 reason : in ordinary fractures of the patella from muscular action 
 the tendinous expansion over it is torn also ; the ends of the bone 
 gape widely, and never unite except by ligament. But in fractures 
 from direct mechanical violence, the tendinous expansion, being 
 entire, maintains the fragments in apposition, so that there is 
 commonly a bony union. 
 
 The femoral artery is a continuation of the external 
 RELATIONS OF iliac. Passing beneath the crural arch at a point about 
 THE FEMORAL uddway between the spine of the ileum and the sym- 
 physis pubis, it descends nearly perpendicularly along 
 the front and inner side of the thigh. At the junction of the 
 upper two-thirds with the lower third of the thigh, it passes 
 through an opening in the tendon of the adductor magnus, and 
 entering the ham, takes the name of ' popliteal.' A line drawn 
 from the point specified of the crural arch to the tubercle of the 
 internal condyle would pretty nearly indicate the course of the 
 artery. Its distance from the surface increases as it descends. Im- 
 mediately under, and for a short distance below the crural arch, it 
 is supported by the inner border of the psoas ; lower down it runs 
 in front of the pectineus, but separated from it by the profimda 
 vessels ; still lower down it lies upon the adductor longus, and ad- 
 ductor magnus. 
 
 In the upper third of the thigh, the artery is situated in Scarpa's 
 triangle, and is comparatively superficial, being covered only by 
 the muscular fascia. About the middle third it is more deeply 
 seated, and is covered by the sartorius : here, being placed among 
 powerful muscles, it is protected from pressure by a tendinous 
 canal, which will be presently examined. 
 
 At the crural arch the anterior crural nerve is placed on the 
 outer side of the artery, and the femoral vein on the inner side : 
 as the vein descends, it gradually passes behind the artery. Both 
 lie close together, and are inclosed in a common sheath. 
 
460 FHOXT OF THE THIGH. 
 
 In the middle third of the thigh, the femoral artery 
 is contained in a tendinous canal * under the sartorius, 
 called ' Hunter's canal.' This canal at its upper pa,rt is 
 rather indistinct ; but it gradually becomes stronger towards the 
 opening in the tendon of the adductor magnus. Its boundaries 
 are formed by the tendons of the muscles between which the 
 artery runs. On the inner side are the tendons of the adductor 
 longus and magnus ; on the outer side is the tendon of the vastus 
 internus ; in front the canal is completed by an aponeurotic ex- 
 pansion thrown obliquely across from the adductors to the vastus 
 internus, as shown in fig. 103. In a horizontal section the canal 
 appears triangular. The adaptation of this shape to the exigencies 
 of the case is manifest when we reflect that the muscles keep the 
 side of the triangle always tight, and thereby prevent any com- 
 pression of the vessels. 
 
 Hunter's canal contains not only the femoral artery and vein, 
 but also the internal saphenous nerve. The vein lies behind and 
 to the outer side ; the nerve to the inner side of the artery. 
 
 It is plain that a ligature can be placed around the artery, in 
 the upper third of the thigh, with comparative facility ; not so 
 pj 103 easily in the middle third. The artery is 
 
 tied for an aneurism of the popliteal, just 
 where the sartorius begins to overlap it, for 
 three reasons: 1, it is more accessible; 2, 
 the coats of the artery at this distance are 
 less likely to be diseased; 3, the origin of 
 the profunda is sufficiently far off to admit 
 
 SECTION THROUGH .... 
 
 HUNTER'S CANAL. of the formation of a coagulum. An incision, 
 i. vastus interims. beginning about three inches below the crural 
 
 I IponeurosSown across, arch, should be made about three inches 
 over the line of the artery. The muscular fascia should be 
 divided over a director to the same extent. Then, by gently 
 
 * Called 'Hunter's canal,' because it was in this part of its course that John 
 Hunter first tied the femoral artery for aneurism of the popliteal, in St. George's Hos- 
 pital, A.D. 1785. The particulars of this interesting case are published in the Trans, 
 for the Improvement of Med. and Chir. Knowledge. 
 
FKONT OF THE THIGH. 461 
 
 drawing aside the inner border of the sartorius, we discover the 
 artery inclosed in its sheath with the vein. An opening should 
 be made into the sheath sufficient to admit the passage of the 
 aneurismal needle, which should be turned round the artery 
 from within outwards. The nerves to be avoided are the long 
 saphenous, which runs along the outer side of the artery, and 
 the cutaneous nerves which cross obliquely over it. 
 
 Having already traced the superficial branches of the femoral 
 artery in the groin, namely, the superficial epigastric, pudic, and 
 circurnflexa ilii (p. 438), we pass on now to the profunda. 
 Profunda ^e profunda is the chief branch of the femoral, and 
 
 artery and is the proper nutrient artery of the thigh. It arises 
 ies ' from the outer and back part of the femoral, about one 
 and a half or two inches below the crural arch, and runs down 
 behind the femoral till it reaches the tendon of the adductor 
 longus ; here the profunda passes behind the adductor, and is 
 finally lost in the hamstring muscles. In most subjects, the 
 profunda, for a short distance after its origin, lies rather on the 
 outer side of the femoral and on a deeper plane, over the iliacus 
 muscle : in this situation it might be mistaken for the femoral 
 itself indeed, such an error has actually occurred in practice. It 
 soon, however, gets behind the femoral, and lies upon the adductor 
 brevis and magnus ; it is separated from the femoral artery at first, 
 by their corresponding veins ; lower down, by the adductor longus.* 
 
 The branches of the profunda generally arise in the following 
 order: 1, the internal circumflex; 2, the external circumflex ; 
 3, the perforating. 
 
 The internal circumflex is given off from the inner part of the 
 profunda, and then sinks deeply into the thigh, between the psoas 
 and pectineus. At the lower border of the obturator externus it 
 terminates in two divisions : one, which supplies the muscles in 
 its neighbourhood, namely, the pectineus, psoas, adductors, gracilis, 
 
 * The point at which the profunda is given off below the crural arch varies very 
 much even in the two limbs of the same body. We have measured it in 19 bodies, or 
 38 femoral arteries. It varied from to 3 inches. In 22 cases the profunda came off 
 between l and 2 inches ; in 9 this distance was exceeded ; in 7 this distance was less. 
 
462 
 
 FRONT OF THE THIGH. 
 
 and obturator externus ; the other will be seen in the dissection of 
 the back of the thigh, between the adductor magnus and the qua- 
 dratus femoris. This division gives off a small articular branch to 
 the hip-joint, which runs through the notch in the acetabulum to 
 the ligamentum teres : it afterwards inosculates with the ischiatic 
 and superior perforating arteries. 
 
 The external circumflex artery comes off from the outer side of 
 the profunda, runs transversely outwards beneath the sartorius and 
 
 Fig. 104. 
 
 1. Crural arch. 
 
 2. Internal iliac. 
 
 3. Femoral. 
 
 4. Profunda. 
 
 5. Internal circumflex. 
 
 6. External circumflex. 
 
 7. First perforating. 
 
 8. Second ditto. 
 
 9. Third ditto. 
 
 10. G-lutasal. 
 
 11. Obturator. 
 
 12. Ischiatic. 
 
 13. Anastomotica magna. 
 
 PLAN OF THE INOSCULATIONS OF THE CIRCUMFLEX ARTERIES. 
 
 rectus, between the branches of the anterior crural nerve, and then 
 subdivides into three sets of branches, 'ascending,' 'transverse,' 
 and 'descending.' The ascending run up to the outer side of 
 
FRONT OF THE THIGH. 463 
 
 the ileum, beneath the tensor fasciae and glutseus medius, supply 
 these muscles, and inosculate with the terminal branches of the glu- 
 tseal artery. The transverse are chiefly lost in the vastus externus, 
 and inosculate posteriorly with the ischiatic artery. The descending, 
 one or more in. number, of considerable size, run down between 
 the rectus and crurseus, and supply both these muscles : one branch, 
 larger than the rest, runs down in the substance of the vastus ex- 
 ternus, along with the nerve to that muscle, and inosculates with 
 the articular branches of the popliteal. 
 
 The perforating branches of the profunda are so named because 
 they pass through the adductors to supply the hamstring muscles. 
 There are generally three, but they vary both in number and size. 
 The first is the largest. It passes between the pectineus and ad- 
 ductor brevis, then through the tendon of the adductor magnus. 
 The second passes through the tendon of the adductor brevis and 
 magnus, and usually furnishes the nutrient artery of the femur. 
 The third, through the tendon of the adductor magnus. They not 
 only supply the hamstring muscles namely, the biceps, semi- 
 tendinosus, and semimembranosus but, also, the vastus externus 
 and glutseus maximus. The perforating arteries inosculate with 
 one another, with the internal circumflex, and with the ischiatic 
 arteries. 
 
 To test your knowledge of the arterial inosculations 
 osculations! about the upper part of the thigh, reflect on the answer 
 to the following questions. If the femoral were tied 
 above the origin of the profunda, how would the circulation be 
 carried on ? The ascending branch of the external circumflex 
 communicates with the glutasal ; the internal circumflex commu- 
 nicates with the obturator and ischiatic (see fig. 104). Again 
 how is the circulation maintained when the femoral is tied below 
 the profunda ? The descending branch, of the external circumflex 
 and the perforating branches of the profunda communicate with 
 the articular branches of the popliteal and the tibial recurrent.* 
 
 * Head the account of the dissection of an aneurismal limb by Sir A. Cooper, Med. 
 Chir. Trans, vol. ii. 
 
464 FRONT OF THE THIGH. 
 
 The continuation of the profimda (sometimes called the fourth 
 perforating), much reduced in size, passes through the tendon of 
 the adductor magnus, and is distributed to the short head of the 
 biceps, finally inosculating with the articular arteries. 
 
 The anastomotica magna arises from the femoral artery just 
 before it leaves its tendinous canal. It runs in front of the 
 tendon of the adductor magnus, in company with the long saphe- 
 nous nerve to the inner side of the knee. Here it divides into 
 two branches : one accompanies the saphenous nerve, and is sub- 
 sequently distributed to the skin ; the other ramifies over the 
 capsule and communicates with the other articular arteries.* 
 
 The anterior crural nerve is the largest branch of 
 . the lumbar plexus (p. 358). It comes from the third 
 and fourth lumbar nerves. It passes beneath the 
 crural arch, lying in the groove between the iliacus and psoas, 
 about a quarter of an inch to the outer side of the artery, and soon 
 divides into branches, some of which are cutaneous, but the greater 
 number supply the exterior muscles of the thigh. The cutaneous 
 branches, already described (p. 441), and the long saphenous 
 nerve, are given off from the superficial part of the trunk ; the 
 muscular from the deep part. 
 
 The long saphenous nerve descends close to the outer side of 
 the femoral artery, and enters the tendinous canal with it in the 
 middle third of the thigh. In the canal it crosses over the artery 
 to its inner side. The nerve leaves the artery just before it 
 becomes popliteal, and then runs in company with the anasto- 
 motica magna to the inner side of the knee, where it becomes 
 superficial, between the gracilis and the sartorius. In the middle 
 third of the thigh it gives off a small branch which communicates 
 with the internal cutaneous and obturator nerves ; and lower 
 down another branch is distributed to the skin over the patella. 
 Its further relations will be seen in the dissection of the leg and 
 foot. 
 
 * In its course down the thigh the femoral artery gives off several small branches 
 io the sartorius, and one of considerable size for the supply of the vastus internus. 
 We may trace this branch through the substance of the vastus down to the patella, 
 where it joins the beautiful network of vessels on the surface of that bone. 
 
FRONT OF THE THIGH. 465 
 
 Its muscular branches are to be traced to the sartorius, rectus, 
 cruraeus, and subcruraeus ; the branch to the vastus externus 
 accompanies the descending branch of the external circumflex 
 artery, and that to the vastus internus runs parallel with, but 
 external to, the long saphenous nerve: these two last-named 
 branches supply articular filaments to the knee-joint. One or 
 more branches pass under the femoral artery and vein to supply 
 the rjectineus. ^^ >w. AJ *tc /^^i^a^^ ia'A/- 
 
 The obturator nerve, also a branch of the lumbar plexus (p. 358), 
 supplies the adductor muscles. It enters the thigh through the 
 upper part of the obturator foramen with the corresponding 
 artery, and immediately divides into two branches, of which one 
 passes in front of, the other behind, the adductor brevis. The 
 front branch* subdivides for the supply of the gracilis, the ad- 
 ductor longus, and sometimes the adductor brevis ; the hind one 
 supplies the obturator externus and the adductor brevis and mag- 
 nus. In some bodies you can succeed in tracing a filament of the 
 obturator nerve through the notch of the acetabulum into the hip- 
 joint, and another, which runs near the popliteal artery into the 
 back part of the knee-joint. We have frequently seen cutaneous 
 branches from the obturator on the inner side of the thigh. This 
 is interesting practically, since it helps to explain the pain often 
 felt on the inner side of the knee in disease of the hip-joint. 
 
 The obturator artery, after passing through the foramen, divides 
 into two branches, which form a circle round the obturator mem- 
 brane. These supply the external obturator and adductors of the 
 thigh, and inosculate with the internal circumflex artery (p. 462). 
 It usually gives off the little artery to the ligamenturn teres of the 
 hip-joint. 
 
 * Near the lower border of the adductor longus, a filament from this branch com- 
 municates with an offset from the long saphenous nerve and with one from the internal 
 cutaneous branch of the anterior crural nerve. This communication takes place over 
 the femoral artery in Hunter's canal. 
 
 II H 
 
466 FRONT OF THE LEG. 
 
 DISSECTION OF THE FRONT OF THE LEG. 
 
 The foot should be turned inwards, and fixed in this position. 
 An incision must be made from the knee, down the front of the 
 leg, over the ankle, along the top of the foot to the great toe ; a 
 second, at right angles to the first, on either side of the ankle ; 
 a third, across the basis of the toes. Eeflect the skin from the 
 front and sides of the leg and foot. 
 
 Cutaneous Having traced the internal saphena vein (p. 441) to 
 
 veins and the inner side of the knee, follow it down the inner 
 side of the leg, in front of the inner ankle * to the top 
 of the foot. On the top of the foot notice that the principal veins 
 form an arch, with the convexity forwards, as on the back of the 
 hand. This arch receives the veins from the toes. From the 
 inner side of the arch the internal saphena originates ; from the 
 outer side, the external saphena. The latter vein runs behind the 
 external ankle, up the back of the calf of the leg to join the 
 popliteal vein. 
 
 The skin on the inner side of the leg is supplied by 
 nouf nervef" the long saphenous nerve (p. 464). It becomes sub- 
 cutaneous on the inner side of the knee, between the 
 gracilis and sartorius. Here it meets the saphena vein, and accom- 
 panies it down the leg, distributing its branches on either side, till 
 it is finally lost on the inner side of the foot and base of the great 
 toe. The largest branch curves round the inner side of the knee, 
 just below the patella,, to supply the skin in this situation. 
 
 The skin on the front and outer part of the upper half of the 
 leg is supplied by cutaneous branches from the external popliteal 
 or peroneal nerve ; the skin of the lower half, by the external 
 cutaneous. ? 
 
 * The French commonly bleed from the internal saphena vein as it crosses over the 
 inner ankle, this being a convenient and safe place for vensesection. 
 
... FRONT OF THE LEG. 467 
 
 External This * s a Branch ^ * ne peroneal nerve : it comes 
 
 cutaneous or throuh the fascia about the lower third of the outer 
 
 f the le ; and desc ^ ndin g over the front of the 
 
 ankle, divides into two branches. Trace its subdivi- 
 sions, and you will find the inner one supplies the inner side of 
 the great toe, and the contiguous sides of the second and third 
 toes ; the outer one distributes branches to the outer side of the 
 third toe, both sides of the fourth, and the inner side of the fifth 
 toe. 
 
 The outside of the little toe is supplied by the external saphe- 
 nous nerve, which runs behind the outer ankle with the correspond- 
 ing vein. 
 
 The contiguous sides of the great and second toes are supplied 
 by the termination of the anterior tibial nerve.* 
 Muscular This is remarkably thick and strong. Besides its 
 
 fascia and general purpose of forming sheaths for the muscles, 
 and s ^aps for the tendons, it gives origin, as in the 
 forearm, to muscular fibres ; so that it cannot be re- 
 moved near the knee, without leaving the muscles ragged. The 
 fascia is attached to the head of the tibia and the fibula : it is 
 identified on the inner side with the expanded tendons of the 
 sartorius, gracilis, and semi-tendinosus ; on the outer side with 
 that of the biceps : consequently, when these muscles act, it is 
 rendered tense. Following it down the leg, you find that it is 
 attached to the edge of the tibia, and that it becomes stronger as 
 it approaches the ankle, to form the ligaments which confine the 
 tendons in this situation. Of these ligaments, called * annular,' 
 there are three, as follow : 
 
 a. The anterior extends obliquely across the front of the ankle- 
 joint, and confines the extensor tendons of the ankle and toes. It 
 consists of two straps, which cross each other over the front of the 
 ankle like braces. One brace goes from the malleolus externus to 
 the scaphoid and internal cuneiform bones ; the other, runs from 
 the cuboid and os calcis upwards and inwards to the inner border 
 
 * Such is the most common distribution of the nerves to the upper surface of the 
 toes. But deviations from this arrangement are frequent. 
 
 H H 2 
 
468 FRONT OF THE LEG. 
 
 of the tibia : it is the strain of this ligament which occasions the 
 pain in sprains of the ankle. You will see presently that it makes 
 a beautiful pulley for the extensor longus digitorum. 
 
 b. The external extends from the outer malleolus to the os calcis, 
 and confines the tendons of the peronei muscles, which draw the 
 foot outwards. 
 
 c. The internal extends from the inner malleolus to the os calcis, 
 and binds down the flexor tendons of the foot and toes. 
 
 Kemove the fascia, leaving enough of the annular ligaments to 
 retain the tendons in their places. 
 
 Muscles on ^ e musc ^ es on the fr n t of the leg are: 1, the 
 the front of tibialis anticus ; 2, the extensor communis digitorum 
 and peroneus tertius ; 3, the extensor proprius pollicis. 
 The tibialis anticus arises from the external tuberosity 
 anc * tbe u PP er two-thirds of the outer side of the tibia, 
 from the interosseous membrane, and from the fascia 
 which covers it. About the lower third of the leg the fibres ter- 
 minate on a strong flat tendon, which descends obliquely over the 
 front of the ankle to the inner side of the foot ; here it becomes a 
 little broader, and is inserted into the internal cuneiform bone and 
 the tarsal end of the metatarsal bone of the great toe. The sy- 
 novial membrane, which lines the sheath of the tendon beneath 
 the annular ligament, accompanies it to within an inch of its in- 
 sertion ; consequently it is opened when the tendon is divided for 
 club-foot. The action of this muscle is to draw the foot upwards 
 and inwards.* When the foot is the fixed point, it assists in 
 balancing the body at the ankle. Its nerve comes from the 
 peroneal. 
 -,, , This muscle lies along the fibular side of the pre- 
 
 Extensor 
 
 ^omniums ceding. It arises from the head of the tibia, from the 
 digitorum. U pp er three-fourths of the fibula, from the interosseous 
 membrane, and the fascia. Its fibres terminate in a penniform 
 manner upon a long tendon, situated on the inner side of the 
 muscle: this tendon descends in front of the ankle and divides 
 
 ' * It is generally necessary to divide this tendon in distortion of the foot inwards, 
 called ' talipes varus.' 
 
FRONT OF THE LEG. 469 
 
 into four slips which pass to the four outer toes. They diverge 
 from each other, and are inserted into the toes thus : on the first 
 phalanx, each tendon (except that of the little toe) is joined on its 
 outer side by the corresponding tendon of the extensor brevis; 
 The united tendons then expand, and are inserted as on the 
 fingers ; that is, the middle part is inserted into the base of the 
 second phalanx ; the sides run on to the base of the third (p. 285). 
 Its nerve comes from the peroneal. 
 
 Immediately below the ankle the anterior annular ligament 
 forms a pulley through which the tendon of this muscle plays. 
 It is like a sling, of which the two ends are attached to the os 
 calcis, while the loop serves to confine the tendon. The play of 
 the tendon is facilitated by a synovial membrane, which is pro- 
 longed for a short distance along each of its four divisions. Be- 
 sides its chief action, this muscle extends the ankle-joint.* 
 
 This appears like a portion of the preceding. Its 
 
 rise fr m the i OW6r P arfc f tbe Shaft f the 
 
 fibula and the interosseous membrane, and terminate 
 on their tendon like barbs on a quill. The tendon passes through 
 the same pulley with the long extensor of the toes, and, expanding 
 considerably, is inserted into the tarsal end of the metatarsal bone of 
 the little toe. It is supplied by a branch of the anterior tibial nerve. 
 The peroneus tertius and the tibialis anticus are important 
 muscles in progression. They raise the toes and foot from the 
 ground. Those who have lost the use of these muscles are obliged 
 to drag the foot along the ground, or to swing the entire limb 
 outwards, in walking. 
 ,, . This muscle lies partly concealed between the tibialis 
 
 Extensor J 
 
 proprius anticus and the extensor longus digitorum. It arises 
 pollicis. from rather more than the middle third of the fibula, 
 and from the interosseous membrane. The fibres terminate in a 
 penniform manner on the tendon, which runs over the ankle, be- 
 tween the tendons of the tibialis anticus and the extensor communis 
 
 * There is often a large bursa between the tendon of the extensor longus digitorum 
 and the outer end of the astragalus. This bursa sometimes communicates with the 
 joint of the head of the astragalus. 
 
470 FRONT OF THE LEG. 
 
 digitorum, along the top of the foot, to the great toe, where it is 
 inserted into the base of the last phalanx. It has a special pulley 
 beneath the annular ligament, lined by a synovial membrane, which 
 accompanies it as far as the metatarsal bone of the great toe. It 
 is supplied by the anterior tibial, a branch of the peroneal nerve. 
 
 Now examine the course, relations, and branches of the anterior 
 tibial artery. Since it lies deeply between the muscles, it is 
 necessary to separate them from each other : this is easily done by 
 proceeding from the ankle towards the knee. 
 
 COURSE AND T ne anterior tibial artery is one of the two branches 
 RELATIONS OF into which the popliteal divides at the lower border of 
 on*TimAL the popliteus. It comes forward about 1 J inch below 
 ARTERY, the head of the fibula, above the interosseous mem- 
 brane, and then descends, lying in rather more than the first half 
 of its course upon the interosseous membrane, afterwards along 
 the front of the tibia. It runs beneath the annular ligament over 
 the front of the ankle, where it takes the name of the dorsal artery 
 of the foot. Thus, a line drawn from the head of the fibula to the 
 interval between the first and second metatarsal bones would nearly 
 coincide with its course. In the upper third of the leg it lies deep 
 J t# i VTJgetween the tibialis anticus and the extensor commnnis digitorum; 
 in the lower two-thirds, between the tibialis anticus and the ex- 
 tensor proprius pollicis. But in front of the ankle the artery is 
 crossed by the extensor proprius pollicis, and lies between the 
 tendon of this muscle and those of the extensor communis digi- 
 torum. 
 
 The artery is accompanied by the anterior tibial nerve (a branch 
 of the peroneal), which runs for some distance upon its fibular 
 side, then in front of it, and lower down is again situated on its 
 outer side. It is accompanied by two veins, one on either side, 
 which communicate at intervals by cross branches. 
 
 The branches of the anterior tibial are as follow: 
 
 a. The recurrent branch ascends close by the outer side of the 
 head of the tibia to the front of the knee-joint, where it inoscu- 
 lates with the other articular arteries derived from the popliteal. 
 
 6. Irregular muscular branches. 
 
FRONT OF THE LEG. 471 
 
 c. The malleolar branches, external and internal, ramify over 
 the ankle, and supply the joint, the articular ends of the bones, 
 and the sheaths of the tendons around them. 
 
 E This muscle is situated on the top of the foot, beneath 
 
 brevis digi- the long extensor tendons of the toes. It arises from 
 torum. ^ e ou er p ar O f f- ne og ca | c i s? an( } from the ligaments 
 
 uniting this bone to the astragalus. The fibres run obliquely over 
 the foot, and terminate on four tendons, which pass forwards to 
 the four inner toes. The innermost one is inserted by an ex- 
 panded tendon into the base of the first phalanx of the great toe ; 
 the others join the fibular side of the long extensor tendons to be 
 inserted into the ungual phalanx. The tendon to the great toe 
 crosses over the dorsal artery of the foot. It is supplied by a 
 branch of the anterior tibial nerve. 
 
 Dorsal ^ Q * s arter y? the continuation of the anterior tibial, 
 
 artery of runs over the instep to the interval between the first 
 D0t ' and second metatarsal bones, where it sinks into the 
 sole and joins the deep plantar arch. On the top of the foot it 
 runs along the outer side of the extensor proprius pollicis, and 
 before it dips down into the sole, is crossed by the short extensor 
 tendon of the great toe. The dorsal artery gives off the following 
 branches : 
 
 a. The tarsal branch arises near the scaphoid bone, passes 
 beneath the extensor brevis digitorum towards the outside of the 
 foot, supplies the bones and joints of the tarsus, and inosculates 
 with the arteries in the sole. 
 
 b. The metatarsal branch generally runs towards the outside of 
 the foot, near the bases of the metatarsal bones, and gives off the 
 three outer interosseous arteries. These pass forwards over the 
 corresponding interosseous muscles, supply them, and then sub- 
 divide to supply the opposite sides of the upper surface of the toes. 
 They communicate by perforating branches with the plantar arteries. 
 
 c. The dorsalis hallucis is, strictly speaking, the artery of the 
 first interosseous space. It comes from the dorsal artery just 
 before this sinks into the sole, and runs forwards to supply both 
 sides of the great toe and the inner side of the second toe. 
 
472 FRONT OF THE LEG. 
 
 These muscles are situated on the outer side of the 
 MuscLEs 1 fibula, and are named, respectively, peroneus longus 
 and brevis. 
 
 This arises from the outer surface of the fibula along 
 Peroneus -^ upper two-thirds. The fibres terminate in a penni- 
 
 longus. 
 
 form manner upon a tendon, which runs through a 
 groove behind the outer ankle, then along the outer side of the os 
 calcis, and, lastly, through a groove on the under surface of the os 
 cuboides deep into the sol It crosses the sole obliquely, and is 
 inserted into the tarsal end of the metatarsal bone of the great 
 toe. In its course through these several bony grooves the tendon 
 is confined by a fibrous sheath, lined by a synovial membrane. In 
 removing the metatarsal bone of the great toe, if possible, leave 
 the insertion of this tendon. Its nerve comes from the peroneal. 
 
 This muscle lies beneath the preceding. It arises from 
 Peroneus about the middle third of the outer surface of the fibula, 
 
 internal to the preceding muscle. It terminates on a 
 tendon which runs behind the outer ankle, through the same 
 sheath with the peroneus longus, then proceeds along the outside 
 of the foot, and is inserted into the tarsal end of the metatarsal bone 
 of the little toe.* Its nerve is from the anterior tibial. 
 
 The action of the peronei is to raise the outer side of the foot.f 
 This movement regulates the bearing of the foot in progression, so 
 as to throw the principal part of the weight on the ball of the great 
 toe. Its action is well exemplified in skating. Again, supposing 
 the fixed point to be at the foot, they tend to prevent the body 
 from falling on the opposite side, as when we balance ourselves on 
 
 one leg. 
 
 Near the inner side of the tendon of the biceps flexor 
 
 Peroneal. ^ ^ e ] e ^ a ] ar g e ne rve called the peroneal, a branch 
 
 of the great ischiatlc. By reflecting the upper part of 
 
 * On the outside of the os calcis there is a ridge which separates the tendons of the 
 peronei. Each has a distinct sheath. The short tendon runs above, the long one be- 
 low the ridge. 
 
 f In distortion of the foot outwards, called ' talipes valgus,' it is generally neces- 
 sary to divide the tendons of the peronei. 
 
GLUTJEAL KEGIOX. 473 
 
 the peroneus longus, you will find that this nerve runs round the 
 outer side of the fibula immediately below its head. Here it divides 
 into several branches, as follow: 1. Three articular branches to 
 the knee-joint, which pass in with the external articular arteries, 
 and the tibial recurrent artery; 2. The anterior tibial, which 
 accompanies the corresponding artery ; 3. The external cutaneous 
 (p. 467), which comes through the fascia between the peroneus 
 longus and the extensor longus digitorum; 4. Branches which 
 supply all the muscles in front of the leg, namely, the extensors of 
 the foot and the toes and the peronei. 
 
 DISSECTION OF THE GLUT^EAL KEGION. 
 
 The body having been placed on its face, rotate the thighs 
 inwards as much as possible, and cross them. 
 
 The incision through the skin should commence at the coccyx, 
 and be continued in a semicircular manner along the crest of the 
 ileum. Another incision should be made from the coccyx down- 
 wards and outwards for about six inches below the great trochanter. 
 In reflecting the skin, notice the thick cushion which the sub- 
 cutaneous adipose tissue forms over the tuberosity of the ischium. 
 
 I have often seen a large bursa between the cushion and the 
 bone. 
 
 These are derived from several sources. The pos- 
 Cutaneous terior divisions of the first and second lumbar nerves 
 
 1161; > CS 
 
 descend over the crest of the ileum, near the origin of 
 the erector spinse, to supply the skin over the glutaeus maximus. 
 Internal to these, are the posterior branches of the sacral nerves, 
 which are distributed to the integument over the sacrum and 
 coccyx. Over the middle of the crest come the lateral branches 
 of the twelfth dorsal, and internal to it, the iliac branch of the ilio- 
 hypogastric. Other cutaneous nerves come up from below ; they 
 are branches of the lesser ischiatic, and proceed from beneath the 
 lower border of the glutseus maximus. Lastly, some branches 
 
474 GLUT^EAL REGION. 
 
 from the external cutaneous nerve of the thigh are seen on the 
 outer side of this region. 
 
 Three powerful muscles are situated on the buttock, 
 muscles one a ^ ove ^ ne ther, named, according to their relative 
 size, the glutseus maximus, medius, and minimus. 
 
 This is the largest muscle of the body, and is covered- 
 ^J a stron g f asc i a > which sends prolongations inwards 
 
 between the muscular bundles. Its great size is cha- 
 racteristic of man, in reference to his erect position. Its texture 
 is thick and coarse. It arises from the posterior fifth of the crest 
 of the ileum, from the lower part of the sacrum, the coccyx, and 
 the great sacro-ischiatic ligament. The fibres descend obliquely 
 forwards, and are inserted thus : the anterior two-thirds terminate 
 on a strong broad tendon which plays over the great trochanter, 
 and joins the fascia lata on the outside of the thigh (p. 443) ; the 
 remaining third is inserted into the femur, along the ridge 
 leading from the linea aspera to the great trochanter. 
 
 This muscle extends the thigh bone upon the pelvis, and is 
 therefore one of those most concerned in raising the body from the 
 sitting to the erect position, and in maintaining it erect. It also 
 propels the body in walking, running, or leaping. It is supplied 
 with blood by the glutseal and ischiatic arteries ; with nerves by 
 the lesser ischiatic. 
 
 The glutseus maximus should be reflected from its 
 
 What is seen . . . . 
 
 beneath the origin. Ihe best way is to begin at the front border, 
 glutoeus maxi- w hich overlaps the glutasus medius. The dissection 
 is difficult, and he who undertakes it for the first time, 
 is almost sure to damage the subjacent parts. The numerous 
 vessels which enter its under surface must be divided before the 
 muscle can be reflected. This having been accomplished, the 
 following objects will be exposed : 
 
 The muscle covering the ileum is the glutoeus medius. At the 
 posterior border of this are the several objects which come out of 
 the pelvis through the great ischiatic notch namely, the py- 
 riformis muscle, above which is the trunk of the glutseal artery and 
 nerve, and below which are the greater and lesser ischiatic nerves, 
 
GLUT^EAL REGION. 475 
 
 the ischiatic artery, and the pudic artery and , nerve. Coming 
 through the lesser ischiatic notch, we see this" tendons' of the 
 obturator internus, and attached to it are the gemelli muscles, one 
 above, the other below it. Extending from the tuber ischii trans- 
 versely outward to the great trochanter is the quadratus femoris, 
 and below this is seen the upper part of the adductor magnus. 
 The origins of the semimembranosus, biceps, semitendinosus, and 
 of the adductor magnus, from the tuber ischii, are also seen ; as 
 well as the great sacro-ischiatic ligament passing upwards to the 
 sacrum. Lastly, the great trochanter is exposed, together with a 
 small portion of the vastus externus ; and where the tendon of the 
 glutseus maximus plays over the trochanter major, there is a large 
 btirsa, simple or multilocular. I have seen it in some subjects 
 sufficiently capacious to hold half a pint of fluid. 
 
 This muscle arises from the surface of the ileum, be- 
 medius S tween the crest and the upper curved line ; also from the 
 
 strong fascia which covers it towards the front. The 
 fibres converge to a tendon which is inserted into the upper and 
 outer surface of the great trochanter : some of the anterior fibres 
 in immediate connection with the tensor fasciae terminate on 
 the aponeurosis of the thigh. 
 
 Eeflect the glutseus medius to see the third glutseal muscle. 
 The line of separation between them is marked by a large branch 
 of the glutseal artery. 
 
 This muscle arises from the surface of the ileum below 
 ilnimus ^ e upper curved line. Its fibres pass over the capsule 
 
 of the hip-joint, and converge to a tendon which is 
 inserted into a depression on the front part of the great trochanter. 
 This muscle and the preceding are supplied by the glutseal nerve. 
 Between the tendon of the last two muscles and the great tro- 
 chanter are two small bursse. The chief action of this and the 
 preceding muscle is to assist in balancing the pelvis steadily on 
 the thigh, as when we are standing on one leg ; with the fixed 
 point at the ileum, it is an abductor of the thigh. The anterior 
 fibres of the glutseus medius co-operate with the tensor fascise in 
 rotating the thigh inwards. 
 
476 GLUT^EAL REGION. 
 
 artery is the largest branch of the iri- 
 vessels and ternal iliac (p. 387). Emerging from the pelvis through 
 ierves. ^ Q g rea j. i sc hi a ti c notch above the pyriformis, it divides 
 into large branches for the supply of the glutseal muscles. Of 
 these, some (superficial) proceed forwards between the glutseus 
 maximus and medius ; others (deep) run in curves between the 
 glutseus medius and minimus, towards the anterior part of the 
 ileum. Many of them inosculate with branches of the external 
 circumflex. 
 
 The nerve which accompanies the glutseal artery is a branch of 
 the lumbo-sacral nerve (p. 391). It subdivides to supply the 
 glutasus medius and minimus, and the tensor fasciae; in some 
 subjects it sends a branch to the glutseus maximus ; but this 
 muscle is chiefly supplied by the lesser ischiatic nerve. 
 
 A practical surgeon ought to be able to cut down and tie the 
 glutseal artery as it emerges from the pelvis. The following is the 
 best rule for finding it : the toes are supposed to be turned in- 
 wards. Draw a line from the posterior superior spine of the ileum 
 to the midspace between the tuber ischii and the great trochanter. 
 The artery emerges from the pelvis at the point where the superior 
 third joins the two inferior thirds of this line.* 
 
 Now examine the series of muscles which rotate the thigh out- 
 wards namely, the pyriformis, the obturator internus, the gemelli, 
 the quadratus femoris, and the obturator externus. 
 
 This muscle lies immediately below and parallel to 
 the lower fibres of the glutseus medius. It arises from 
 the front surface of the sacrum between the holes for the sacral 
 nerves, and from the margin of the great sacro -ischiatic notch. 
 The fibres converge to a tendon which is inserted into the upper 
 border of the trochanter major. Its nerve comes from the sacral 
 plexus. 
 
 This muscle, of which we can at present see little 
 
 internus r more than the tendon, arises within the pelvis, from the 
 
 ischium between the great ischiatic notch and the obtu- 
 
 * The operation of tying the glutseal artery was first performed by John Bell. See 
 his ' Principles of Surgery,' vol. i. p. 421. 
 
GLUT^AL REGION. 477 
 
 rator foramen ; also from the obturator membrane. The fibres 
 terminate on four tendons which converge towards the lesser ischi- 
 atic notch, pass round it as round a pulley, and then uniting into 
 one, are inserted into the top of the great trochanter. Divide the 
 tendon about three inches from its insertion, to see the four ten- 
 dons which play over the smooth cartilaginous pulley. There is a 
 large synovial bursa to prevent friction. The nerve of this muscle 
 comes from the sacral plexus ; sometimes from the pudic nerve. 
 
 These muscles are accessory to the obturator interims, 
 and are situated, one above, the other below it. The 
 gemellus superior arises from the spine of the ischium ; the gemellus 
 inferior from the upper part of the tuberosity. Their fibres are 
 inserted into the tendon of the obturator internus. Both muscles 
 derive their nerves from the sacral plexus. 
 
 This muscle arises from the ridge on the outer part of 
 the tuber iscDii - Its nbres run horizontally outwards, 
 and are inserted into the back of the great trochanter, in 
 a line with the linea aspera. Notice that the lower border of the 
 quadrat us femoris runs parallel with the upper edge of the ad- 
 ductor magnus ; in fact, it lies on the same plane. Between these 
 muscles is generally seen a terminal branch of the internal circum- 
 flex artery. Its nerve comes from the sacral plexus. 
 
 To see this muscle reflect the quadratus femoris. It 
 ar i ses from the front surface of the ramus of the pubes 
 and ischium, and from the obturator membrane. The 
 fibres converge to a tendon which runs horizontally outwards over 
 a groove in the ischium, and is inserted into the deepest part of 
 the pit of the great trochanter. Its nerve is a branch of the 
 obturator (p. 358). 
 
 Great This large nerve is formed by the union of the sacral 
 
 ischiatic nerves (fig. 105), and is destined to supply all the flexor 
 muscles of the lower extremity, and the extensors of the 
 foot. 
 
 Emerging from the pelvis through the great ischiatic foramen 
 below the pyriformis, it descends over the external rotator mus- 
 cles of the thigh, along the interval between the tuber ischii and 
 
478 
 
 GLUT^EAL REGION. 
 
 the great trochanter, but rather nearer to the former ; so that, in 
 the sitting position, the nerve is protected from pressure by this 
 bony prominence. The nerve does not descend quite perpendicu- 
 larly, but rather obliquely forwards, parallel with the great sacro- 
 
 Fig. 105. 
 
 LUMB* 
 
 12. N. of pyriformis. 
 
 13. N. of gemellus superior. 
 
 14. N. of gemellus inferior. 
 
 15. N. of quadratus femoris. 
 
 16. N. of glutseus maximus. 
 
 1 7. Long pudendal n. 
 
 18. Cutaneous n. of the but- 
 
 tock. 
 
 19. N. of the long head of 
 
 the biceps. 
 
 20. N. of semitendinosus. 
 
 21. N. of semimembrano- 
 
 sus. 
 
 22. N. of short head of the 
 
 biceps. 
 
 1, 2, 3, 4, 5. Sacral nn. 
 
 6. Superior glutaeal n. 
 
 7. Great ischiatic n. 
 
 8. Lesser ischiatic n. 
 
 9. Pudic n. 
 
 10. N. of obturator interims. 
 
 11. N. of levator ani. 
 
 PLAN OF THE SACEAL PLEXUS AND BRANCHES. 
 
 ischiatic ligament. It is accompanied by a branch of the ischiatic 
 
 artery, called the ' comes nervi ischiatici.^ * 
 
 r This comes from the lower part of the sacral plexus. 
 
 JLjCSSGl? 
 
 ischiatic It leaves the pelvis with the greater ischiatic nerve, 
 but on the inner side of it, and in company with the 
 
 * The arteria comes nervi ischiatici runs generally by the side of the nerve, but 
 sometimes in the centre of it. This artery becomes one of the chief channels by which 
 the blood reaches the lower limb after ligature of the femoral. See a preparation in 
 the Museum of St. Bartholomew's Hospital, where the femoral was tied by John 
 Hunter fifty years before the man's death. 
 
POPLITEAL SPACE. 479 
 
 ischiatic artery. The muscular branches which it gives off are, 
 one or more, which enter the under surface of the glutaeus maxi- 
 mus. All its other branches are cutaneous. One turns round the 
 lower border of the glutseus maximus, and supplies the skin of 
 the buttock. Another, the long pudendal (p. 367), turns inwards 
 towards the perineum, to supply the skin of that region and the 
 scrotum. The continued trunk runs down the back of the thigh 
 beneath the muscular fascia, as low as the upper part of the calf, 
 supplying the skin all the way down. 
 
 This branch of the internal iliac leaves the pelvis 
 artery/ below the pyriformis, and then descends between the 
 
 tuber ischii and the great trochanter, along the inner [\ CL 
 side of the great ischiatic nerve. It gives off 1, two or more '}' 
 considerable branches to the glutseus maximus ; 2, a coccygeal 
 branch, which runs through the great sacro-ischiatic ligament, 
 then ramifies in the glutaaus maximus, and on the back of the 
 coccyx ; 3, the comes nervi ischiatici ; 4, branches to the several 
 external rotator muscles ; lastly, branches which supply the upper 
 part of the hamstring muscles ; and others which inosculate with 
 the internal circumflex and obturator arteries (p. 462). 
 
 The course of this artery and nerve has been fully 
 and nerved described (p. 374). Observe now that they pass over 
 
 the spine of the ischium, accompanied by the nerve to 
 the obturator internus, and that in a thin subject it is possible to 
 compress the artery against the spine. The rule for finding it is 
 this : rotate the foot inwards, and draw a line from the top of the 
 great trochanter to the base of the coccyx; the junction of 
 the inner with the outer two-thirds gives the situation of the 
 artery.* 
 
 It is advisable to examine the popliteal space at this 
 
 stage of the dissection, in order that the various parts 
 
 may be carefully made out with as little disturbance 
 as possible of their mutual relations. 
 
 A vertical incision must be made along the middle of the ham, 
 
 * Mr. Travers succeeded in arresting haemorrhage from a sloughing ulcer of the 
 glans penis by pressing the pudic artery with a cork against the spine of the ischium. 
 
480 POPLITEAL SPACE. 
 
 extending from six inches above, to three inches below the knee : 
 transverse incisions should be made at each extremity of the 
 vertical, so that the skin may be conveniently reflected. In doing 
 so, care must be taken to preserve the cutaneous branch of the 
 lesser ischiatic nerve, which descends over the ham to the back of 
 the leg. 
 
 The muscular fascia covering the space is very strong, and 
 strengthened by numerous transverse fibres. It is traversed by 
 the posterior saphena vein, which passes to join the popliteal 
 vein. 
 
 The fascia having been reflected, the muscles and tendons 
 constituting the boundaries of the popliteal space are to be cleaned. 
 The space is formed, above, by the divergence of the hamstring 
 muscles to reach their respective insertions; below, by the con- 
 verging origins of the gastrocnemius : its shape is therefore that 
 of a lozenge. Above it is bounded on the inner side by the 
 semitendinosus, semimembranosus, gracilis, and sartorius ; on the, 
 outer side, by the biceps ; below, it is bounded on the inner side 
 by the internal head of the gastrocnemius, on the outer, by the 
 external head of this muscle and the plantaris. 
 
 The space is occupied by a quantity of fat, which permits the 
 easy flexion of the knee ; and in this fat are found imbedded the 
 popliteal vessels and nerves, in the following order : nearest to 
 the surface are the nerves ; the vessels lie close to the bone, the 
 vein being superficial to the artery (fig. 106). 
 
 Along the outer border of the semimembranosus is the great 
 iscbiatic nerve, which, after giving off branches to the three great 
 flexor muscles, divides, about the lower third of the thigh (higher 
 or lower in different subjects), into two large nerves the peroneal 
 and the popliteal. 
 
 The peroneal runs close by the inner side of the tendon of the 
 biceps* towards the head of the fibula, below which we have al- 
 ready traced its division into branches for the peronei, and all the 
 extensors of the foot and toes (p. 472). 
 
 * The nerve is, therefore, very liable to be injured in the operation of dividing the 
 outer hamstring. 
 
POPLITEAL SPACE. 
 
 481 
 
 The popliteal accompanies the popliteal artery, and is destined 
 to supply all the flexor muscles on the back of the leg and the 
 sole of the foot. 
 
 By clearing out all the fat, we observe that the popliteal vessels 
 enter the ham through an aperture in the adductor magnus, and 
 
 Fig. 106. 
 
 Semitendinosus 
 
 Semimembranosus. 
 Gracilis. 
 
 Sartoriua. 
 
 Inner head of gastrocne- 
 mius. 
 
 POPLITEAL SPACE. 
 
 descend close to the back part of the femur, and the back of the 
 knee-joint. At first they are partially overlapped (in muscular 
 subjects), by the Semimembranosus ; indeed the outer border of 
 this muscle is a good guide to the artery in the operation of tying 
 it. Arising at right angles from the popliteal artery, are the two 
 superior articular arteries: close to the vessel is the articular 
 branch of the obturator nerve which supplies the knee-joint. 
 
 i i 
 
482 BACK OF THE THIGH. 
 
 Two or more absorbent glands are situated one on 
 
 glands 6I eac -k s ^ e f t ne ar tery. They deserve attention, 
 because, when enlarged, their close proximity to the 
 artery may give them an apparent pulsation which might be mis- 
 taken for an aneurism. 
 
 DISSECTION OF THE BACK OF THE THIGH. 
 
 The incision should be continued along the back of the thigh, 
 and the skin reflected. 
 
 The skin at the back of the thigh is supplied by the 
 
 Cutaneous ......... . 
 
 nerves and lesser ischiatic nerve, which runs down beneath the 
 veins. fascia, as low as the upper third of the calf, distributing 
 
 branches on either side. 
 
 There are no subcutaneous veins of any size at the back of the 
 thigh : here they would be liable to pressure. But near the ham 
 we find a vein, called the * external saphena.' It comes up the 
 back of the calf, and joins the popliteal vein. 
 
 Respecting this, remark that its fibres run chiefly in 
 Muscular a t ransverse direction, that it becomes stronger as it 
 
 faSCla< T 1 J 
 
 passes over the popliteal space, and that here it is con- 
 nected with the tendons on either side. Remove it, to examine 
 the powerful muscles which bend the leg, called the ' hamstrings.' 
 There are three of these, and all arise by strong 
 Hamstring tendons from the tuber ischii. One, the biceps, is 
 
 muscles. m " 
 
 inserted into the head of the fibula ; the other two 
 namely, the semitendinosus and semimembranosus are inserted 
 into the tibia. The divergence of these muscles towards their 
 respective insertions occasions the space termed the ' ham,' which 
 is occupied by soft fat, and the popliteal vessels and nerves. 
 
 This muscle has two origins, a long and a short, 
 
 The long one takes place, by a strong tendon, from the 
 back part of the tuber ischii ; the short one, by fleshy fibres, from 
 the linea aspera of the femur. This origin begins at the linea 
 aspera, just below the insertion of the gltitseus maximus, and con- 
 
BACK OF THE THIGH. 483 
 
 tinues nearly down to the external condyle. It joins the longer 
 part of the muscle, and both terminate on a common tendon, 
 which is inserted into the head of the fibula, by two portions sepa- 
 rated by the external lateral ligament of the knee-joint. It also 
 gives off a strong expansion to the fascia of the leg. The tendon 
 covers part of the external lateral ligament of the knee-joint, and 
 a small bursa intervenes.* 
 
 The biceps is not only a flexor of the leg, but rotates the leg, 
 when bent, outwards. It is this muscle which dislocates the knee 
 outwards and backwards in chronic disease of the joint. Each 
 portion of the biceps is supplied by the great ischiatic nerve. The 
 short head is sometimes supplied by the peroneal. 
 
 This arises, in common with the biceps, also by mus- 
 cular fibres internal to the common origin, from the 
 back part of the tuber ischii. The fibres terminate 
 upon a long tendon, which spreads out below the knee-joint, and 
 is inserted into the inner surface of the tibia, below the tendon of 
 the gracilis, and behind that of the sartorius. Like them, it plays 
 over the internal lateral ligament of the knee, and is provided 
 with a bursa to prevent friction. Its nerve comes from the 
 ischiatic. 
 
 The semitendinosus sends off from the lower border of its tendon 
 a very strong fascia to cover the leg, which is attached along the 
 inner edge of the tibia. The middle of the muscle is intersected 
 by an oblique tendinous line. 
 
 This muscle arises from the tuber ischii above and 
 bra^osug 1 " external to the two preceding, by means of a strong 
 flat tendon, which extends nearly half way down the 
 thigh. This tendon descends obliquely behind the biceps and 
 semitendinosus, and terminates in a bulky muscle, which lies on a 
 deeper plane than the others, and is inserted by a thick tendon 
 into the posterior part of the head of the tibia. In connection 
 with this tendon, notice three additional points : 1, that it is 
 prolonged under the internal lateral ligament of the knee, and 
 
 * This tendon can be plainly felt as the outer hamstring in one's own person, just 
 above the head of the fibula. 
 
 ii 2 
 
484 
 
 BACK OF THE THIGH. 
 
 that a bursa intervenes between them ; 2, that it sends a strong 
 prolongation upwards and outwards to the external condyle of the 
 femur, forming the principal constituent of the s ligamentum 
 posticum Winslowii, which covers the back of the knee-joint ; 
 3, that a fascia proceeds from its lower border, and binds down the 
 popliteus. Its nerve comes from the ischiatic. 
 
 A large bursa is almost invariably found between the semi- 
 membranosus and the inner head of the gastrocnemius, where 
 they rub one against the other. It is generally from one and a 
 half to two inches long. The chief point of interest concerning it 
 is, that it occasionally communicates with the synovial membrane 
 of the knee-joint, not directly, but through 
 Fig. 107. the medium of another bursa beneath the 
 
 inner head of the gastrocnemius. From 
 an examination of 150 bodies, I infer that 
 this communication exists about once in 
 five instances ; and it need scarcely be said 
 that the proportion is large enough to 
 make us cautious in interfering too roughly 
 with this bursa when it becomes enlarged.* 
 
 Action of the These muscles produce two 
 hamstring different effects, according as 
 
 muscles. 
 
 or the knee. With the fixed point at the 
 pelvis, they bend the knee; with the fixed 
 point at the knee, they form a very im- 
 portant part of the machinery which keeps 
 the body erect. For instance, if, when 
 standing, you bend the body at the hip 
 and feel the muscles in question, you find 
 that they are in strong action, to prevent 
 
 * When the bursa in question becomes enlarged, it occasions a fluctuating swelling 
 of greater or less dimensions on the inner side of the popliteal space. The swelling 
 bulges out, and becomes tense and elastic when the knee is extended, and vice versa. 
 As to its shape, it is generally oblong ; but this is subject to variety, for we know that 
 the bursse, when enlarged, are apt to become multilocular, and to burrow between 
 the muscles where there is the least resistance. 
 
CALF OF THE LEG. 485 
 
 the trunk from falling forwards : they, too, are the chief agents 
 concerned in bringing the body back again to the erect position. 
 In doing this, they act upon a lever of the first order, as shown in 
 fig. 107 ; the acetabulum being the fulcrum F, the trunk w, the 
 weight to be moved, and the power p, at the tuber ischii. 
 
 To put the action of the muscles of the thigh on the pelvis in 
 the clearest point of view, let us suppose we are standing upon one 
 leg : the bones of the lower extremity represent a pillar which sup- 
 ports the weight of the trunk on a ball-and-sccket joint ; the weight 
 is nicely balanced on all sides, and prevented from falling by four 
 groups of muscles. In front, are the rectus and sartorius ; on the 
 inner side, the adductors ; on the outer side, the glutseus medius 
 and minimus ; behind, the hamstrings and glutasus maximus. 
 
 The semimembrariosus can also rotate the knee inwards, thus 
 assisting the popliteus. 
 
 The hamstring muscles are supplied with blood by the perfor- 
 ating branches of the profunda, which come through the tendon 
 of the adductor magnus close to the femur. Their nerves are 
 derived from the great ischiatic. 
 
 This nerve descends from the buttock upon the ad- 
 ductor , magnus, and, after being crossed by the long 
 head of the biceps, runs along the outer border of the 
 semimembranosus down the popliteal space. The further course 
 of this nerve has already been described (p. 480). 
 
 Deferring the course, relations, and branches of the popliteal 
 artery till this vessel is exposed throughout its whole course, pass 
 on now to the dissection of the calf. 
 
 Continue the incision down the centre of the calf to the heel, 
 and reflect the skin. 
 
 External or ^ ne l ar g e ve i n seen on the back of the leg is called the 
 posterior sa- f external or posterior saphena.' It commences on the 
 P ena vein. ou ^ er s ^ e O f ^ e f oo ^ rung b e hj nc i ^he outer ankle, and 
 
 then up the calf, receiving numerous veins in its course. It eventu- 
 ally passes through the muscular fascia, and joins the popliteal vein. 
 The chief cutaneous nerve of the calf is the external or posterior 
 
486 CALF OF THE LEG. 
 
 saphenous nerve ; some branches, however, from the long saphenous 
 and small ischiatic nerves, are to be traced, ramifying in the sub- 
 cutaneous tissue of the inner and upper part of the leg. 
 
 The external sapkenous nerve * is derived from the 
 posterior popliteal (fig. 106), and passes down between the two 
 saphenous heads of the gastrocnemius to the middle of the calf, 
 
 nerve 
 
 where it >comes through the fascia. Here it is joined 
 by a branch from the peroneal nerve (communicans peronei); it 
 then descends with the saphenous vein, and is finally distributed 
 to the outer side of the foot and the little toe. 
 
 To expose the muscles of the calf, reflect the muscular fascia 
 by incisions corresponding to those made through the skin. 
 
 The great flexor muscle of the foot consists of two 
 MUSCLES OF p 0r tj O ns : the superficial one, called the ( gastrocnemius,' 
 
 THE CAL.F. * 
 
 arises from the lower end of the femur ; the deep one, 
 called the ' soleus,' arises from the tibia and fibula. The force 
 of both is concentrated on one thick tendon, called the ' tendo 
 Achillis,' which is inserted into the heel. 
 
 This muscle arises by two strong tendinous heads. 
 
 Gastrocnemius. f ,-> ,11,1 r u Jif 
 
 one from the upper and back part 01 each condyle ot 
 the femur (fig. 106). The inner head is the larger. The two parts 
 of the muscle descend, distinct from each other, and form the two 
 bellies of the calf, of which the inner is rather the lower. Both 
 terminate, rather below the middle of the leg, on the broad com- 
 mencement of the tendo Achillis. 
 
 The gastrocnemius should be divided transversely near its 
 insertion, and reflected upwards from the subjacent soleus, as high 
 as its origin. By this proceeding you observe that the contiguous 
 surfaces of the muscles are covered by a glistening tendon, which 
 receives the insertion of their fibres, and transmits their collected 
 force to the tendo Achillis. 
 
 Observe also the large sural vessels and nerves (branches of the 
 popliteal ) which supply each head of the muscle. To facilitate the 
 play of the inner tendon over the condyle, there is a bursa, which 
 
 * This nerve is sometimes called the communicans poplitei, and does not take the 
 name of external saphenous till its junction with the communicans peronei. 
 
CALF OF THE LEG. 487 
 
 generally communicates with the knee-joint; and in the substance 
 of the outer tendon is commonly found a small piece of fibro- 
 cartilage. Lastly, between the gastrocnemius and soleus is the 
 tendon of the plantaris. 
 
 This small muscle* arises from the rough line just above 
 the outer condyle of the femur (^fig. 106). It descends 
 close to the inner side of the outer head of the gastrocnemius, and 
 terminates, a little below the knee, in a long tendon, which should 
 be traced down the inner side of the tendo Achillis to the calca- 
 neum. Its nerve comes from the popliteal. 
 
 This muscle arises from the head and upper third of 
 the posterior surface of the fibula, from the oblique 
 ridge on the back of the tibia, f from about the middle third of 
 the inner border of this bone, and from an arch thrown over the 
 posterior tibial vessels. The fibres swell out . beneath the gas- 
 trocnemius, and terminate on a broad tendon, which, gradually 
 contracting, forms a constituent part of the tendo Achillis. The 
 soleus is supplied with blood by several branches from the posterior 
 tibial ; also by a large branch from the peroneal. Its nerve comes 
 from the popliteal and enters the top of the muscle. This is an 
 important muscle in a surgical point of view, for two reasons 1, 
 by reflecting its tibial origin, we reach the posterior tibial artery ; 
 2, by reflecting its fibular origin we reach the peroneal. 
 
 The tendo Achillis begins about the middle of the leg, and is at 
 first of considerable breadth, but it gradually contracts and becomes 
 thicker as it descends. The narrowest part of it is about one inch 
 and a half above the heel ; here, therefore, it can be most con-- 
 veniently and safely divided for the relief of club-foot. There is 
 no risk of injuring the deeper-seated parts, because they are 
 separated from the tendon by a quantity of fat. Its precise inser- 
 
 * This is the representative of the palmaris longus of the forearm. In man it is 
 lost on the calcaneum, but in monkeys, who have prehensile feet, ife is the proper 
 tensor muscle of the plantar fascia. It is remarkably strong in bears and plantigrade 
 mammals. 
 
 f The tibial and fibular origins of the soleus constitute what some anatomists de- 
 scribe as the two heads of the muscle. Between them descend the popliteal vessels^ 
 protected by a tendinous arch. 
 
488 CALF OF THE LEG. 
 
 tion is into the under and back part of the os calcis. The tendon 
 previously expands a little : between it and the bone is a bursa of 
 considerable size. 
 
 The action of the gastrocnemius and soleus is to raise the body 
 on the toes. Since the gastrocnemius passes over two joints, it 
 has the power (like the rectus) of extending the one while it bends 
 the other, and it is, therefore, admirably adapted to the purpose of 
 walking. For instance, by first extending the foot it raises the 
 body, and then, by bending the knee, it transmits the weight from 
 one leg to the other. Supposing the fixed point to be at the heel, 
 the gastrocnemius is also concerned in keeping the body erect, for 
 it keeps the tibia and fibula perpendicular on the foot, and thus 
 counteracts the tendency of the body to fall forwards. 
 
 The tendo Achillis, in raising the body on tiptoe, acts with 
 Fig. 108. great power and under the best lever- 
 
 age ; for it acts upon a lever of the 
 first order. The fulcrum (a movable 
 one) is at the ankle-joint F, fig. 108; 
 the weight, w, at the toes ; the power 
 at the heel, p. All the conditions are 
 those of a lever of the first order. The 
 power and the weight act in the same 
 direction on opposite sides of the ful- 
 crum. The pressure upon the fulcrum 
 is equal to the sum of the pressures applied : i. e. p x F + w x F.* 
 
 After passing through the opening in the tendon of 
 
 COURSE AND r > L 
 
 RELATIONS OF PS adductor magnus, the femoral artery takes the 
 name of ( popliteal.' It descends nearly perpendicularly 
 behind the knee-joint, between the origins of the 
 gastrocnemius, as far as 'the lower border of the popliteus, where it 
 divides into the anterior and posterior tibial. In its descent it 
 lies, first, upon the lower part of the femur, and here it is slightly 
 overlapped by the semimembranosus ; next it lies upon the 
 posterior ligament of the knee-joint, and, lastly, upon the popliteus. 
 
 * It is fair to state that some regard the foot as a lever of the second order. There 
 is, therefore, room for two opinions on the question. 
 
 THE POPLITEAL 
 ARTERY. 
 
CALF OF THE LEG. 489 
 
 It is covered by the gastrocnemius and soleus, and is crossed by 
 the plantaris. The vein closely accompanies the artery, and is 
 situated superficially with regard to it, and rather to its outer side 
 in the first part of its course. The popliteal nerve runs also in a 
 similar direction with the vein, but is still more superficial and to 
 the outer side (fig. 106). The vessels and the nerve are surrounded 
 by fat, and one or two absorbent glands are generally found in the 
 immediate neighbourhood of the artery, jut above the joint. 
 
 The branches of the popliteal artery are the articular and the 
 sural. 
 
 There are five articular branches for the supply of the knee- 
 joint and the articular ends of the bone: the two superior- -ex- 
 ternal and internal run, one above each condyle, close to the. 
 bone, and are distributed partially to the vastus externus and 
 interDus, respectively ; the two inferior external and internal 
 run, one beneath each lateral ligament of the joint; and all four 
 proceed towards the front of the capsule. The fifth, called the 
 6 azygos,' enters the joint through the posterior ligament. These 
 articular arteries form, over the front and sides of the joint, a 
 beautiful network of vessels, which communicate, supe- 
 riorl y> witn the descending branch of the external cir- 
 cumflex and the anastomotica magna ; inferiorly, with 
 the anterior tibial recurrent. It is mainly through these channels 
 that the collateral circulation is established in the leg after ligature 
 of the femoral. 
 
 The sural arteries proceed one to each head of the gastrocne- 
 mius, and are proportionate in size to the muscle. One or two 
 branches are distributed to the soleus. These arteries are accom- 
 panied by branches of the popliteal nerve for the supply of the 
 muscles. 
 
 This vein is fcrmed by the junction of the venae 
 comites of the anterior and posterior tibial arteries, 
 and is situated superficial to the artery. It crosses 
 obliquely from the inner to the outer side of the artery, and is 
 continued upwards under the name of femoral. It receives in the 
 popliteal space the external saphena, the articular, and sural veins. 
 
490 CALF OF THE LEG. 
 
 The insertion of the semimembranosus into the head of the 
 tibia, alluded to p. 483, should now be more fully examined. 
 
 This muscle arises within the capsule of the knee- 
 op it ms. j om t, from a depression on the outside of the external 
 condyle by a thick tendon, which runs beneath the external lateral 
 ligament. The muscular fibres gradually spread out, and are in- 
 serted into the posterior surface of the tibia above the oblique 
 ridge on the bone. 1^. is supplied by a branch of the popliteal 
 nerve which enters its deep surface. Its action is to flex the leg, 
 and then to rotate the tibia inwards. The tendon plays over the 
 articulation between the tibia and fibula ; and a bursa intervenes, 
 which generally communicates by a wide opening with the knee- 
 joint. 
 
 Keflect the soleus with its origin, and remove it from the deep- 
 seated muscles, observing at the same time the numerous arteries 
 which enter its under surface. This done, notice the fascia which 
 binds down the deep muscles. It is attached to the margin of 
 the bones on either side, and increases in strength towards the 
 ankle, in order to form an annular ligament to confine the tendons 
 and the vessels and nerves in their passage into the sole of the 
 foot. 
 
 ^ There are three: 1, the flexor longus digitorum on 
 
 ON THE BACK the tibial side ; 2, the flexor longus pollicis on the 
 OF THE LEG. fib^j. . 3^ ^Q tibialis posticus upon the interosseous 
 membrane, between and beneath them both. 
 
 This arises from the posterior surface of the tibia, 
 commencing below the popliteus, and extending to 
 within about four inches of the lower end of the bone. 
 The fibres terminate on a tendon which runs through a groove 
 behind the inner ankle, and entering the sole, divides into four 
 tendons for the four outer toes. It is supplied by the posterior 
 tibial nerve. 
 
 This powerful muscle arises from the lower two-thirds 
 the posterior surface of the fibula. The fibres ter- 
 minate on a tendon which runs through a groove on 
 the back of the astragalus, and thence along the sole to the 
 
CALF OF THE LEG. 491 
 
 great toe. The action of this muscle is to raise the body on the 
 tip of the great toe. It is essential to the propulsion of the body 
 in walking. It is supplied by the posterior tibial nerve. 
 
 This is so concealed between the two preceding muscles, 
 it cannot be properly examined without reflecting 
 them. It arises from the interosseous membrane and 
 from the contiguous surfaces of the tibia and fibula. In the 
 lower part of the leg it passes between the tibia and the flexor 
 longus digitorum. Its muscular fibres terminate on a tendon 
 which comes into view a short distance above the inner ankle, and, 
 running through the same groove with the tendon of the flexor 
 longus digitorum, enters the sole, and is inserted into the scaphoid 
 and internal cuneiform bones. Its action is to bend and turn the 
 foot inwards. It is supplied by the posterior tibial nerve. The 
 precise situation of the tendon of the tibialis posticus is interesting, 
 surgically, because the tendon has to be divided for the relief of 
 talipes varus. It lies close to, and parallel with, the inner edge 
 of the tibia, so that this is a good guide to it. It is necessary to 
 relax the tendon, while the knife is introduced between the tendon 
 and the bone. Its synovial sheath commences about 1^ inch above 
 the end of the internal malleolus, and is consequently opened in 
 the operation. 
 
 Attention should now be directed to the internal annular 
 ligament, which binds down the tendons behind the inner 
 ankle. 
 
 It is attached to the internal malleolus and the inner border of 
 the os calcis. It is continuous above with the deep fascia, below 
 with the plantar fascia. Beneath it pass the tendons of the deep- 
 seated muscles of the leg into the sole of the foot. The relative 
 position of the structures passing under this ligament, proceeding 
 from within outwards, are the tendons of the tibialis posticus, and 
 the flexor longus digitorum; the posterior tibial artery accom- 
 panied by its venae comites ; the posterior tibial nerve ; and, lastly, 
 the tendon of the flexor longus pollicis. 
 
 Course and ^is artery is one of the branches into which the 
 relations of popliteal divides at the lower border of the popliteus. 
 
492 CALF OF THE LEG. 
 
 the posterior It descends over the deep muscles at the back of the 
 tibial artery. j e g J.Q ^he interval between the internal malleolus and 
 the os calcis, and, entering the sole, divides behind the abductor 
 pollicis into the external and internal plantar arteries. It lies, 
 first, for a short distance, upon the tibialis posticus, then, on the 
 flexor longus digitorum ; but behind the ankle it is in contact with 
 the tibia, so that here it can be felt beating, and effectually com- 
 pressed. In the upper part of its course, it runs nearly midway 
 between the bones, and is covered by the gastrocnemius and soleus : 
 to tie it, therefore, in this situation, is very difficult. But in the 
 lower part of its course, it gradually approaches the inner border 
 of the tibia, from which, generally speaking, it is not more than 
 ^ or fths of an inch distant. Here, being comparatively superficial, 
 it may easily be tied. Immediately behind the internal malleolus, 
 it lies between the tendons of the flexor longus digitorum, on the 
 inner side, and the flexor longus pollicis on the outer. It has two 
 venae comites, which communicate at intervals. Its branches are 
 as follow: 
 
 a. Numerous branches to the soleus and the deep muscles. 
 6. The peroneal is a branch of very considerable size ; often as 
 large as the posterior tibial. Arising about 1-J- inch below the divi- 
 sion of the popliteal, it descends close to the inner side of the fibula, 
 and then over the articulation between the tibia and fibula to the 
 outer part of the os calcis, where it inosculates with the malleolar 
 and plantar arteries. All down the leg it is imbedded among the 
 muscles : being covered, first, by the soleus, afterwards by the 
 flexor longus pollicis. To both these muscles, to the latter especi- 
 ally, it sends numerous branches, and just above the ankle it gives 
 off a constant one the anterior peroneal which passes through 
 the interosseous membrane, to the under aspect of the peroneus 
 
 n tertius, then runs in front of the tibio-fibular articulation, 
 - Q***^ " inosculates with the other malleolar arteries.yy It supplies the 
 
 ^'medullary artery of the fibula, and, about an inch above the os calcis, 
 sends off a transyersa-^ommunicating branch, which inosculates 
 with the posterior tibia] artery under the tendon of the flexor 
 longus pollicis. A&to ^ ^ 44 a. 
 
 0* 
 
 iff**- 
 
SOLE OF THE FOOT. 493 
 
 c. The medullary artery of the tibia.J^/~ ^&*o &*. d^y** 
 Posterior This is the continuation of the popliteal. It descends 
 
 tibial nerve, close to its corresponding artery, and, entering the sole of 
 the foot, divides into the external and internal plantar nerve. In 
 the first part of its course the nerve lies superficial to the artery, 
 and rather to its inner side ; but behind the ankle the nerve lies 
 on the outer side of the artery, and on the same plane.* It 
 supplies branches to the three deep-seated muscles, and a cutaneous 
 branch to the sole of the foot. 
 
 DISSECTION OF THE SOLE OF THE FOOT. 
 
 Make a perpendicular incision down the middle of the sole, and 
 reflect the skin. Notice the peculiar structure of the subcutaneous 
 tissue. It is composed of globular masses of fat, separated by 
 strong fibrous septa, and forms elastic pads, especially marked at the 
 heel, and at the ball of the great and the little toe ; these being the 
 points which form the tripod supporting the arch of the foot. 
 
 In removing the subcutaneous tissue from the ball of the great 
 and the little toe, we often meet with bursae, simple or multilocular. 
 They are generally placed between the skin and the sesamoid bones, 
 and have remarkably thick walls. Very frequently we trace an 
 artery and nerve running directly through one of these sacs, which 
 explains the acute pain produced by their inflammation. 
 
 The skin of the heel is supplied by a branch of the 
 posterior tibial nerve ; the remainder of the sole by 
 small branches of the plantar nerves which come through 
 the fascia, as in the palm of the hand. 
 
 This is remarkably dense and strong. It extends from 
 Plantar ^ under and back part of the os calcis to the distal 
 
 jascia. 
 
 ends of the metatarsal bones : it not only protects the 
 plantar vessels and nerves, but is one of the many structures which 
 support the arch of the foot. It acts like the string of a bow 
 
 * It sometimes happens that the nerve divides into its two plantar branches higher 
 than usual, and then we find that one lies on either side of the artery. 
 
494 SOLE OF THE FOOT. 
 
 (p. 508). This is exemplified in some cases of distortion, where 
 an unnatural contraction of the plantar fascia makes the arch of 
 the foot too convex ; and it is necessary to divide the fascia to 
 relieve the deformity. 
 
 The arrangement of the fascia is like that in the palm. The 
 central part, where there is the greatest strain, is very strong. The 
 external part, which is attached to the proximal end of the fifth 
 metatarsal bone, is also very strong. Near the distal ends of the 
 metatarsal bones, the central part divides into five portions ; each 
 of these subdivides into two slips, which embrace the corresponding 
 flexor tendons, and are attached to the metatarsal bones and their 
 connecting ligaments. Between the primary divisions of the 
 fascia that is, in a line_j)etwe_en the toes are seen the digital, 
 vessels and nerves.. 
 
 In the interdigital folds of the skin, there are also ligamentous 
 fibres, which ran from one side of the foot to the other, and answer 
 the same purpose as those in the hand (p. 257). 
 
 The plantar fascia must be partially removed to examine the 
 muscles. Towards the os calcis its removal is not accomplished 
 without some difficulty, because the muscles arise from it. 
 
 After the removal of the fascia three muscles are 
 
 MEs CIAL ex P sed - A11 arise from the os calcis and the fascia, 
 and proceed forwards to the toes.* The central one is 
 the flexor brevis digitorum, the two lateral are the ahduct-or 
 pollicis, and the abductor minimi digiti. 
 
 This muscle arises from the inner and back part of 
 ^ e og Ca i c j g? f r om the plantar fascia, and the internal 
 annular ligament. Its origin arches over the plantar 
 vessels and nerves in their passage to the sole. The fibres run 
 along the inner side of the sole, and terminate on a tendon which 
 is inserted into the inner side of the base of the first phalanx of 
 the great toe, through the medium of the internal sesamoid bone. 
 Its nerve comes from the internal plantar. 
 
 * They are separated from each other by strong perpendicular partitions intermus- 
 cular septa which pass in from the plantar fascia. 
 
SOLE OF THE FOOT, 49-5 
 
 Abductor *^ s mu scle has a very strong origin from the under 
 
 minimi surface of the os calcis, from its external tubercle and 
 
 digiti. ^ e pi an t ar fascia. Some of its fibres terminate on a 
 
 tendon which is inserted into the proximal end of the metatarsal 
 bone of the little toe ; but the greater part runs on to a tendon 
 which is inserted into the outer side of the first phalanx of the 
 little toe. It is supplied by the external plantar nerve. 
 
 This muscle arises from the under surface of the 
 digJtorum! os ca l ci * s > between the two preceding, from the plantar 
 fascia and the intermuscular septa. It passes forwards 
 and divides into four tendons, which run superficial to those of 
 the long flexor. Cut open the sheath which contains them ; follow 
 them on to the toes, to see that each bifurcates over the first 
 phalanx, to allow the long tendon to pass ; then the two slips, 
 reuniting, are inserted into the sides of the second phalanx. The 
 same arrangement prevails as in the fingers. It is supplied by the 
 internal plantar jneryfi. 
 
 The three superficial muscles should now be reflected, by sawiog 
 off about half an inch of the os calcis, and then turning it down- 
 wards with the preceding muscles attached to it. This done, we 
 bring into view the plantar vessels and nerves, the second layer of 
 muscles, i.e. the long flexor tendon of the great toe, that of the 
 other toes, and the flexor accessorius. 
 
 Tendon of the Tracing this tendon into the sole, you find that an 
 flexor longus accessory muscle is attached to it. The flexor acces- 
 
 digitorum. . . , . .,. , .'.. . i ,. 
 
 Musculus ac- sorius arises by muscular fibres trom the inner side of 
 cessorius. ^he os ca lcis, an d has often a second origin, tendinous, 
 from the outer side. Its fibres run straight forwards, and are 
 inserted into the fibular side of the tendon, so that their action is 
 not only to assist in bending the toes, but to make the common 
 tendon pull in a straight line towards the heel, which, from its 
 oblique direction, it could not do without the accessory muscle. 
 The common tendon then divides into four, one for each of the 
 four outer toes. These run in the same sheath with the short 
 tendons, and after passing through them are inserted into the 
 bases of the ungual phalanges. Respecting the manner in which 
 
496 SOLE OF THE FOOT. 
 
 the tendons are confined by fibrous sheaths, and lubricated by a 
 synovial lining, what was said of the fingers (p. 262) applies 
 equally to the toes. The flexor accessorius is supplied by the 
 external plantar nerve. 
 
 These four little muscles are placed between the long 
 Lumbricales. 
 
 flexor tendons. Each, excepting the most internal, 
 
 arises from the adjacent sides of two tendons, proceeds forwards, 
 and then sinking between the toes, terminates in an aponeurosis 
 which passes round the inner side of the four outer toes, and joins 
 the extensor tendon on the dorsum of the toes. Concerning their 
 use, refer to p. 264. The two outer lumbricales are supplied by 
 the externaLplaD.ta.r nerve, the two inner by the internal plantar. 
 
 Now trace the long flexor tendon of the great toe. From the 
 groove in the astragalus it runs along the groove in the lesser 
 tuberosity of the os calcis, above the tendon of the flexor longus 
 digitorum, and then straight to the base of the last phalanx. 
 Observe that it crosses the long flexor tendon of the toes, and that 
 the two tendons are connected by an oblique slip ; so that we can- 
 not bend the other toes without the great toe. 
 
 The posterior tibial artery, having entered the sole 
 ARTERIES between the origins of the abductor pollicis, divides 
 into the external and internal plantar arteries. 
 
 The internal plantar artery is very small : it passes forwards 
 between the abductor pollicis and the flexor brevis digitorum to 
 the base of the great toe, where it terminates in small inoscu- 
 lations with the digital arteries. Its chief use is to supply the 
 muscles between which it runs. 
 
 The external plantar is the principal artery of the sole, and 
 alone forms the plantar arch. It runs obliquely outwards across 
 the sole towards the base of the fifth metatarsal bone ; then, 
 sinking deep from the surface, it bends inwards across the bases of 
 the metatarsal bones, and inosculates with the anterior tibial in the 
 first interosseous space. In the first part of its course, it lies 
 between the flexor brevis digitorum and the flexor accessorius; in 
 the second it lies very deep beneath the flexor tendons, and the 
 adductor pollicis, close to the metatarsal bones. Deeply seated as 
 
SOLE OF THE FOOT.. 
 
 497 
 
 it appears to be, a part of its curve near the fifth metatarsal bone 
 lies immediately beneath the fascia. Here it might be more 
 easily tied than in any other part of its Fig. 109. 
 
 course. 
 
 Its chief branches are the four digital ar- 
 teries, which arise in the arched part of its 
 course. They supply both sides of the fifth, 
 fourth, third, and the outer side of the second 
 toe ; the great toe, and the inside of the se- 
 cond, being supplied by the dorsalis hallucis. 
 Concerning the distribution of the digital ar- 
 teries, refer to the account given of these 
 arteries in the hand ; they are in all respects 
 similar (p. 259). 
 
 Besides the digital arteries, the arch gives 
 off three small branches the perforating 
 which ascend between the three outer meta- 
 tarsal spaces, and inosculate with the dorsal 
 interosseous arteries. 
 
 The posterior tibial nerve di- 
 vides, like the artery, into an ex- , 
 
 _ J ' 1. Internal plantar. 
 
 ternal and internal plantar. The 2 - External do. 
 internal plantar is generally the larger, and supplies nerves to 
 three toes and a half, like the median in the palm. It also sup- 
 plies the muscles on the inner side of the sole, the abductor 
 pollicis, the flexor brevis pollicis, the flexor brevis digitorum, 
 the two inner lumbricales; also articular branches to the tarsus 
 and metatarsus. The external plantar nerve sends branches to 
 the flexor accessorius and the abductor minimi digiti, and then 
 divides into a superficial and deep branch. The superficial 
 branch supplies the fifth toe and the outer side of the fourth 
 toe (like the ulnar nerve in the palm), and the flexor brevis 
 minimi digiti. The deep branch furnishes nerves to the two 
 outer lumbricales, the adductor pollicis, the transversalis pedis, 
 and all the interossei. 
 
 K K 
 
 Plantar 
 nerves. 
 
498 SOLE OF THE FOOT. 
 
 Having traced the principal vessels and nerves, di- 
 f muscles./ v ^ e them with the flexor tendons near the os calcis, 
 
 and turn them down toward the toes, to expose the 
 deep muscles in the sole. These are, the flexor brevis and ad- 
 ductor pollicis, the flexor brevis minimi digiti, and the transversalis 
 pedis. 
 
 This muscle arises from the external cuneiform and 
 poUicis r 1S cu bid bones. It proceeds along the metatarsal bone 
 
 of the great toe, and divides into two portions, which 
 run one on each side of the long flexor tendon, and are inserted 
 by tendons into the sides of the first phalanx of the great toe. 
 The inner tendon is inseparably connected with the abductor 
 pollicis, the outer with the adductor pollicis. In each tendon 
 there is a sesamoid bone. These bones not only increase the 
 strength of the muscle, but both together form a pulley for the 
 free play of the long flexor tendon ; so that in walking the tendon 
 is not pressed upon. Its nerve comes from the internal plantar. 
 This very powerful muscle arises from the cuboid, 
 
 and the third and fourth metatarsal bones. Passing 
 
 obliquely across the foot, it is inserted through the 
 external sesamoid bone into the outer side of the base of the first 
 phalanx of the great toe together with the inner head of the 
 flexor brevis pollicis. This muscle greatly contributes to support 
 the arch of the foot. Like the adductor of the thumb it should be 
 considered as an interosseous muscle. 
 
 This little muscle arises from the base of the fifth 
 
 metatarsal ^one, P rocee ds forwards along it, and is 
 
 inserted into the base of the first phalanx of the little 
 toe. 
 
 This slender muscle runs transversely across the 
 Transversalis distal ends of the metatarsal bones. It arises by little 
 
 fleshy slips from the four outer toes, and is inserted 
 into the first phalanx of the great toe with the adductor pollicis, 
 of which it ought to be considered a part. 
 
 The fourth layer of muscles consists of the interossei. 
 
 vsx > 
 
SOLE OF THE FOOT. 499 
 
 These muscles are arranged nearly like those in the 
 palm. They occupy the intervals between the meta- 
 tarsal bones, and are seven irt number, four being on the dorsal 
 aspect of the foot, three on the plantar. They arise from the 
 sides of the metatarsal bones, and terminate in tendons which are 
 inserted, some into the inner, others into the outer side of the 
 first phalanges of the toes and their extensor tendons. Their use 
 is to draw the toes to or from each other, and they do this or that 
 according to the side of the phalanx on which they act. Now, if 
 we draw an imaginary longitudinal line through the second toe, 
 we find that all the dorsal muscles draw from that line, and 
 the plantar towards it. This is the key to the action of them all. 
 A more detailed account ef these muscles is given in the dissection 
 of the palm (p. 292). Between the tendons of the interossei, that 
 is, between the distal ends of the metatarsal bones, there are little 
 bursaB to facilitate movement. These bursae are not without 
 interest. They sometimes become enlarged and occasion painful 
 swellings between the roots of the toes. The flexor brevis minimi 
 digiti, the transversalis pedis, and all the interossei are supplied 
 by the external plantar fierve T 
 
 Now trace the tendons of the peroneus longus and tibialis 
 posticus. The tendon of the peroneus longus is the deepest in 
 the sole. It runs through a groove in the cuboid bone obliquely 
 across the sole towards its insertion into the outer side of the base 
 of the metatarsal bone of the great toe. It is confined in a strong 
 fibrous sheath, lined throughout by synovial membrane. 
 
 The tendon of the tibialis posticus may be traced over the 
 internal lateral ligament of the ankle, and thence under the 
 head of the astragalus to the scaphoid bone into which it is chiefly 
 inserted. One or two slips are sent off to the cuneiform bones. 
 Observe that the tendon contributes to support the head of the 
 astragalus, and that for this purpose it often contains a sesamoid 
 bone. This is one of the many provisions for the solidity of the 
 arch of the foot. 
 
500 
 
 LIGAMENTS OF THE PELVIS. 
 
 DISSECTION OF THE LIGAMENTS. 
 
 The sacrum is united to the last lumbar vertebra in 
 ^ e same manner as one vertebra is to another. The 
 same observation applies to the union between the 
 sacrum and the coccyx. The student should, therefore, refer to 
 the description of the ligaments of the spine (p. 210). 
 
 The innominate bones are connected to each other in front, 
 constituting the ' symphysis pubis ; ' posteriorly to the sacrum, 
 constituting the ( sacro-iliac symphysis. 9 
 
 Fig. 110. 
 
 Great sacro-ischiatic ligament. 
 Lesser Bacro-ischiatic ligament. 
 
 Ilio-femoral or accessory 
 ligament of the hip-joint. 
 
 This is secured by, 1, an anterior ligament, consisting 
 ^ su P ei *fi c i a l fibres which run obliquely, and of deep 
 fibres which pass transversely ; 2, a posterior ligament, 
 less distinct ; 3, a sub-pubic ligament, or ( ligamentum arcuatum : ' 
 it is very strong, and rounds off the point of the pubic arch ; 4, a 
 superior ligament which passes across the upper surface of the 
 pubic bones ; 5, an intermediate fibro-cartilage. A perpendicular 
 section through it shows that it consists of concentric layers, and 
 
LIGAMENTS OF THE HIP, 501 
 
 that its general structure resembles that between the bodies of the 
 vertebrae. In the upper part of this fibre-cartilage is a smooth 
 cavity lined with epithelium. The cartilage acts like a buffer, and 
 breaks the force of shocks passing through the pelvic arch. 
 
 The ileum is connected with the fifth lumbar vertebra by the 
 ilio-lumbar ligament. It is very strong, and extends from the 
 transverse process of the last lumbar vertebra to the crest of the 
 ileum (fig. 111). 
 
 This is secured by, 1, an anterior ligament which 
 s a mh sis consists of ligamentous fibres passing in front; 2, a 
 posterior ligament, composed of fibres much stronger 
 and more marked, which pass behind the articulation. The 
 anterior part of the bones forming this articulation is crusted with 
 articular cartilage, of which the shape is like that of the ear. 
 Behind this is the strong interosseous ligament, which contributes 
 powerfully to the security of the joint. 
 
 These are two strong ligaments passing from the 
 sacrum to tne ischium. The great sacro-ischiatic 
 extends from the posterior inferior spine of the ileum, 
 and the side of the sacrum and coccyx, to the tuberosity of 
 the ischium. The lesser sacro-ischiatic ligament passes from 
 the sacrum and coccyx to the spine of the ischium. These 
 two ligaments not only connect the bones, but also, from their 
 great breadth, contribute to block up the lower aperture of the 
 pelvis. 
 
 LIGAMENTS OF ^^ s joint is secured by the form of the bones, and 
 THE HIP- by the strength of the powerful muscles which surround 
 JOINT. Alth ough a perfect ball-and-socket joint, its motion 
 
 is somewhat limited : the disposition of its ligaments restricts its 
 range of motion to those directions only which are most consistent 
 with the maintenance of the erect attitude, and the requirements 
 of this part of the skeleton. 
 
 The capsular ligament is attached above to the 
 Capsular circumference of the acetabulum at a little distance 
 
 ligament. 
 
 external to the margin, and also to the transverse 
 ligament ; below to the inter-trochanteric ridge of the femur in front, 
 
502 
 
 LIGAMENTS OF THE HIP 
 
 and to the middle of the neck behind. The capsule is made 
 exceedingly thick and strong in front, by a broad ligament, ilio- 
 femoral, which extends from the anterior inferior iliac spine to the 
 anterior inter-trochanteric line. This ligament is very strong, and 
 serves as a strap to prevent the femur being extended beyond a 
 certain limit ; and to prevent the body from rolling backwards at 
 
 the hip. 
 
 Fig. 111. 
 Ilio-lumbar ligament 
 
 Interogseous ligament 
 
 Ligamen- 
 tum teres. 
 
 Open the capsule to as- 
 certain the enormous thick- 
 ness of it in front, and the 
 strong hold it has upon the 
 bones. This exposes the coty- 
 loid ligament, and the liga- 
 mentum teres. 
 
 Theligamentum 
 teres is exposed by 
 drawing the head 
 of the femur out of the socket. 
 This ligament is somewhat 
 Hat and triangular. Its base 
 is attached, below, to the 
 borders of the notch in the 
 acetabulum ; its apex to the 
 fossa in the head of the femur. 
 To prevent pressure on it, 
 and to allow free room for its 
 play, there is a gap at the 
 bottom of the acetabulum. This gap is not crusted with cartilage 
 like the rest of the socket, but is occupied by soft fat. The liga- 
 mentum teres is surrounded by the synovial membrane. A little 
 artery runs up with it to the head of the femur. It is a branch of 
 the obturator, and enters the acetabulum through the notch at the 
 lower part. 
 
 The chief use of the ligamentum teres is to assist in steadying 
 the pelvis on the thigh in the erect position. In this position, the 
 ligament is vertical, and quite tight (fig. Ill): it therefore prevents 
 
 VERTICAL SECTION THROUGH THE HIP. 
 
LIGAMENTS OF THE KNEE. 503 
 
 the pelvis from rolling towards the opposite side, or the thigh from 
 being adducted beyond a certain point. Another purpose served 
 by this ligament is to limit rotation of the thigh, both inwards and 
 outwards. 
 
 The cotyloid ligament is a piece of fibro-cartilage 
 ligament which is attached all round the margin of the aceta- 
 bulum. Its circumference is thicker than its free 
 margin which shelves off; thus it not only deepens the cavity, but 
 embraces the head of the femur like a sucker. It extends over 
 the notch at the lower part of the acetabulum, and in this situation 
 has received the name of the f transverse ' ligament. 
 
 The ligaments of the hip are so arranged, that when we f stand 
 at ease,' the pelvis is spontaneously thrown into a position in 
 which its range of motion is the most restricted ; for the accessory 
 ligament (ilio femoral) of the capsule prevents it from rolling 
 backwards, and the ligamentum teres prevents its rolling towards 
 the opposite side. This arrangement economises muscular force 
 in balancing the trunk. 
 
 The synovial membrane extends down to the base of the neck of 
 the femur in front, but only two-thirds down behind. It is laid 
 upon a thick periosteum. 
 
 The head of the thigh-bone is kept in the acetabulum by at- 
 mospheric pressure ; the amount of this is, of itself, sufficient to 
 keep the limb suspended from the pelvis, supposing all muscles 
 and ligaments to be divided. When fluid is effused into the hip- 
 joint, the influence of the atmospheric pressure is diminished in 
 proportion ; and the bones being no longer maintained in accurate 
 contact, it sometimes happens that the head of the femur escapes 
 from its cavity, giving rise to what is called a spontaneous dis- 
 location. 
 
 LIGAMENTS ^ ne knee-joint is a hinge-joint, and looking at the 
 OF THE skeleton, one would suppose that it was very insecure. 
 KNEE-JOINT. -g u j. na t- ure h as made up for this apparent insecurity 
 by powerful ligaments, and by surrounding the joint on all sides 
 with a thick capsule formed by the tendons of the muscles which 
 move it. 
 
504 
 
 LIGAMENTS OF THE KNEE. 
 
 First examine the tendons concerned in the con- 
 ligament struction of the capsular ligament. In front is the 
 ligamentum patellae ; on either side are the tendons of 
 the vasti; at the back of the joint four tendons contribute to 
 form the capsule namely, the tendons of the gastrocnemius, the 
 tendon of the semimembranosus, and of the popliteus. It 
 deserves to be noticed that the weakest part of the capsule is 
 near the tendon of the popliteus : here, therefore, matter formed in 
 the popliteal space may make its way into the joint, or vice versa. 
 Exclusive of the capsule, the proper ligaments of the joint are 
 I, the lateral ; 2, the crucial in the interior. 
 
 This is a broad flat band, which extends from the 
 inner cond J le of the femur to the inner side of the 
 tibia, a little below its head. A few of the deeper 
 fibres are attached to the inner semi-lunar cartilage, and serve to 
 keep it in place. The inferior internal articular artery, and part 
 of the tendon of the semimembranosus, pass underneath this 
 ligament. In the several motions of the joint, there is a certain 
 
 amount of friction between the liga- 
 ment and the head of the tibia, and con- 
 sequently a small bursa is interposed. 
 
 This is a strong round 
 band > which extends from 
 the outer condyle of the 
 femur to the head of the fibula. This 
 ligament separates the two divisions 
 of the tendinous insertion of the biceps. 
 Posterior to, and running parallel with, 
 the external lateral ligament is a 
 smaller band of fibres, called the short 
 external lateral ligament. 
 
 This, which is generally 
 lament. called ^ ligamentum posti- 
 cum Winslowii,' consists of 
 expansions derived from the tendons at 
 the back of the joint, chiefly, however, 
 
 Fig. 112. 
 
 1. Internal lateral ligament. 
 
 2. External ditto. 
 
LIGAMENTS OF THE KNEE. 
 
 505 
 
 Fig. 113. 
 
 from the semimembranosus. It not only closes and protects the 
 joint behind, but prevents its extension beyond the perpendicular. 
 The joint should be opened above the patella. Observe the 
 great extent of the fold which the synovial membrane forms above 
 this bone.* The use of it is to allow the free play of the bone 
 over the lower part of the femur. The fold extends higher above 
 the inner than the outer condyle, which accounts for the form of 
 the swelling produced by effusion into the joint. 
 Folds of Below the patella a slender band of the synovial 
 
 synovial membrane proceeds backwards to the space between 
 membrane. ^ cond yi es< j t i s ca n e( i the f ligamentum mu- 
 
 cosum : ' the edges of it are called the ' ligamenta alaria.' These 
 are not true ligaments, but merely remnants of 
 the partition, which, in the early stage of the 
 joint's growth, divided it into two halves. 
 
 Immediately outside the synovial membrane 
 there is always more or less fat ; especially under 
 the ligamentum patellae. Its use is to fill up 
 vacuities, and to mould itself to the several move- 
 ments of the joint. 
 
 The crucial ligaments, so named 
 ligaments because they cross like the letter X, 
 
 extend from the mesial side of each 
 condyle to the head of the tibia. The anterior, 
 a, b, the smaller, ascends from the fossa in front 
 of the spine of the tibia, backwards and outwards 
 to the external condyle. The posterior, c, d, best 
 seen from behind, extends from the fossa behind 
 the spine of the tibia forwards to the inner condyle. 
 
 Between the condyles and the articular surfaces of 
 cularor the tibia are two incomplete rings of fibro-cartilage, 
 semi-lunar shaped like the letter C. They serve to deepen the 
 
 articular surfaces of the tibia ; their mobility and elas- 
 ticity enable them to adapt themselves to the condyles in the 
 
 a, 6. Anterior crucial 
 
 ligament. 
 
 c, d. Posterior ditto. 
 e. Tibio-fibular. 
 
 * In performing operations near the knee, the joint should always be bent in order 
 to draw the pynovial fold as much as possible out of the way. 
 
506 LIGAMENTS OF THE KNEE. 
 
 several movements of the joint; they distribute pressure over a 
 greater surface ; they equalise pressure ,and prevent shocks. They 
 are thickest at the circumference, and gradually shelve off to a 
 thin margin : thus they fit in between the bones, and adapt a 
 convex surface to a flat one, as shown in fig. 112. Their form 
 is suited to the condyles ; the inner being oval, the outer circular. 
 The ends of each are firmly attached by ligaments to the pits in 
 front and behind the spine of the tibia ; but the ends of the in- 
 ternal one are attached further from the spine than the external. 
 The cartilages are connected in front by a thin e transverse ' liga- 
 ment ; and their circumference is attached round the head of the 
 tibia by fibrous tissue (called the ' coronary ' ligament), yet not so 
 closely as to restrict their range of motion.* 
 
 Their respective points of attachment are such, that 
 Hgamcnts! wnen tne j oint i g extended, all the ligaments are tight, 
 to prevent extension beyond the perpendicular; thus 
 muscular force is economised. But when the joint is bent the 
 ligaments are relaxed, enough to admit a slight rotatory movement 
 of the tibia. This movement is more free outwards than inwards ; 
 and is effected, not by rotation of the tibia op its own 
 Fig. 114. axis, but by rotation of the outer head round the inner. 
 Eotation outwards is produced by the biceps ; rotation 
 inwards by the popliteus and semimembranosus. 
 
 The crucial ligaments, though placed inside the joint, 
 answer the same purposes as the coronoid process and 
 the olecranon of the elbow. They make the tibia slide 
 properly forwards and backwards. The anterior espe- 
 cially limits extension ; the posterior, flexion. They 
 not only prevent dislocation in front or behind, but 
 they prevent lateral displacement, since they cross each other like 
 braces, as shown in fig. 114. 
 
 * Of the two cartilages the external has the greater freedom of motion, because in 
 rotation of the knee the outer side of the tibia moves more than the inner. Conse- 
 quently, it is not in any way connected to the lateral ligament ; so far from this, it is 
 separated from it by the tendon of the popliteus, of which the play is facilitated by a 
 bursa communicating freely with the joint. For this reason the external cartilage ia 
 more liable to dislocation. 
 
LIGAMENTS OF THE ANKLE. 507 
 
 There is a distinct joint between the upper ends of 
 CONNECTING the .tibia and fibula, although it admits of little move- 
 _THE TIBIA ment. It is firmly secured by oblique ligaments in 
 front and behind ; their fibres being directed down- 
 wards and outwards (p. 505). The contiguous surfaces of the 
 bones are crusted with cartilage. In the great majority of in- 
 stances its synovial membrane is independent ; but it occasionally 
 communicates with the synovial membrane of the knee. 
 
 The shafts of the bones are connected by the in- 
 terosseous membrane. The purpose of this is to afford 
 additional surface for the attachment of muscles. Its 
 fibres pass chiefly downwards and outwards from the tibia to the 
 fibula, but some cross like the letter X. The anterior tibial artery 
 comes forward above the interosseous membrane. It is perforated 
 here and there for the passage of blood vessels. 
 
 The lower ends of the tibia and fibula are most firmly 
 
 Inferior tibio- . . J 
 
 fibular liga- connected, for it is essential to the solidity of the ankle- 
 ments. joint that there be no motion between them. They are 
 
 secured by an oblique ligament in front and behind, and by strong 
 ligamentous fibres, interosseous, which connect their contiguous 
 surfaces, and answer the purpose of rivets. Besides the.se, a strong 
 fibro-cartilaginous ligament proceeds from the end of the fibula, 
 and is attached along the posterior border of the articular surface 
 of the tibia. The object of it is to deepen the excavation of the 
 tibia, and enable it to adapt itself more accurately to the articular 
 surface of the astragalus. 
 
 LIGAMENTS From the form of the bones, it is obvious that the 
 OF THE ankle is a hinge-joint ; consequently, its security de- 
 ANKZE- JOINT. p en j g U p 0n the g reat strength of its lateral ligaments. 
 The hinge, however, is not so perfect but that it admits of a slight 
 rotatory motion, of which the centre is on the fibular side, and 
 therefore the reverse of that in the case of the knee. 
 
 This ligament, sometimes called, from its shape, 
 lateral 1 ' deltoid,' is exceedingly thick and strong, and com- 
 pensates for the comparative shortness of the malleolus 
 on this side (fig. 115). The great strength of it is proved by the 
 
508 LIGAMENTS OF THE ANKLE. 
 
 fact, that in dislocations of the ankle inwards, the summit of the 
 malleolus is more likely to be broken off than the ligament to be 
 torn. It extends from a deep excavation at the apex of the 
 malleolus, radiates from this point, and is attached to the side of 
 the astragalus, also to the os calcis, and the scaphoid bone. 
 Besides this, some of its fibres are inserted into, and become 
 
 Fig. 115. 
 
 1. Plantar fascia. 
 
 2. Calcaneo-scaphoid or elastic ligament which supports the head of the astragalus. 
 
 3. Internal lateral ligament, called from its shape deltoid. 
 
 identified with, the inferior calcaneo-scaphoid ligament, so as to 
 brace it up internally (fig. 115). 
 
 This ligament consists of three distinct parts an 
 lateral. anterior, a posterior, and a middle (fig. 116). All three 
 arise from an excavation near the summit of the external 
 malleolus ; the first two are inserted into the front and the 
 back of the astragalus respectively ; the middle into the outer sur- 
 face of the os calcis. 
 
 Anterior and *^ ne c l sure f ^ ne joint is completed, in front and 
 posterior behind, by an anterior and a posterior ligament attached 
 igament, ^ ^ e ] 3oneg near their articular surfaces, and sufficiently 
 loose to permit the necessary range of motion. 
 
LIGAMENTS OF THE ANKLE. 
 
 509 
 
 Fig. 116. 
 
 Besides flexion and extension, the ankle-joint admits of a slight 
 lateral movement, only permitted in the extended state of the 
 joint. This is useful to us in the di- 
 rection of our steps. In adaptation to 
 this movement the internal malleolus is 
 made shorter than the outer ; it is not 
 so tightly confined by its ligaments, and 
 its articular surface is part of a cylinder. 
 
 Open the joint to see that the breadth 
 of the articular surfaces of the bones is 
 greater in front than behind. The ob- 
 ject of this is to render the astragalus 
 less liable to be dislocated backwards. 
 Whenever this happens, the astragalus 
 must of necessity become firmly locked 
 between the malleoli. 
 
 The astragalus is the 
 CONNECTING key-stone of the arch of the 
 THE BONES OF f oo t, and supports the whole 
 
 THE FOOT. . , , ,. . , , , T . 
 
 weight of the body. It arti- 
 culates with the os calcis and the os sca- 
 phoides in such a manner as to permit 
 the abduction and adduction of the 
 foot, so useful in the direction of our steps. 
 
 The astragalus articulates with the os calcis by two distinct 
 surfaces, respecting which remark, that the anterior is slightly 
 convex, and the posterior slightly concave. This adaptation of 
 itself contributes much to prevent the separation of the bones. 
 
 But their principal bond of union is a strong interosse- 
 
 ous lig amen t which occupies the interval between them 
 
 (fig. 116). 
 
 In the skeleton the head of the astragalus articulates in front 
 with the os scaphoides, but a part of it is unsupported below. In 
 Calcaneo ^ s interval it is supported by a very strong and elastic 
 scaphoid ligament, which extends from the os calcis to the os 
 ligament. sca phoides (fig. 117). These bones, together with the 
 
 DIAGRAM OF THE EXTERNAL LATE- 
 RAL LIGAMENT. 
 
 1. Anterior part. 
 
 2. Posterior part. 
 
 3. Middle part. 
 
 4. Interosseous ligament. 
 
510 
 
 LIGAMENTS OF THE SOLE OF THE FOOT. 
 
 Fig. 117. 
 
 ligament, form a complete socket for the head of the astragalus ; it 
 is this joint, chiefly, which permits the abduction and adduction 
 of the foot. The chief peculiarity about the 
 ligament is its elasticity. It acts in all re- 
 spects like a spring, and allows to the key- 
 stone of the arch a certain amount of play 
 which is of great service in preventing con- 
 cussion of the body. Whenever this ligament 
 loses its elastic property, as is often the case 
 with those who are in the habit of carrying 
 heavy burdens, the arch of the foot gradually 
 yields, and the individual becomes flat-footed. 
 The os calcis articulates with the os cuboides 
 nearly on a line with the articulation between 
 the astragalus and the os scaphoides. The 
 Calcaneo- bones are most firmly connected by 
 cuboid means of a powerful ligament in 
 
 the sole, called the calcaneo-cuboid, 
 or ' ligamentum longum plantae.' Some of its 
 fibres extend forwards as far as the second, third, 
 and fourth metatarsal bones. 
 It would be tedious to enumerate individually the several liga- 
 ments which connect the remaining bones of the tarsus and meta- 
 tarsus. Let it then suffice to say, that they are firmly braced 
 together by very strong ligaments, both on their dorsal and their 
 plantar surfaces, and by interosseous ligaments which extend be- 
 
 1. Calcaneo- scaphoid li- 
 
 gament. 
 
 2. Calcaneo-cuboid liga- 
 
 ment. 
 
 Fig. 118. 
 
 tween their contiguous surfaces, like rivets. 
 Though there is very little motion between 
 any two bones, the collective amount is such 
 that the foot is enabled to adapt itself accur- 
 ately to the ground ; pressure is more equally 
 distributed, and consequently there is a firmer 
 basis for the support of the body. Being composed, moreover, of 
 several pieces, each of which possesses a certain elasticity, the 
 foot gains a general springiness and solidity which could not have 
 resulted from a single bone. 
 
 the wedge bones. 
 
DISSECTION OF THE BRAIN. 511 
 
 S novial Exclusive of the ankle-joint and the phalanges of the 
 
 membranes toes, the bones of the foot are provided with six dis- 
 of the tarsus. ft nc t gynovial membranes ; namely 
 
 Of. Between the posterior articular surface of the astragalus and 
 os calcis. 
 
 6. Between the head of the astragalus and the scaphoid, and 
 between the anterior articular surface of the astragalus and os calcis. 
 
 c. Between the os calcis and the os cuboides. 
 
 d. Between the inner cuneiform bone and the metatarsal bone 
 of the great toe. 
 
 e. Between the scaphoid and the three cuneiform bones, and be- 
 tween these and the adjoining bones (the great toe excepted). 
 
 /. Between the os cuboides and the fourth and fifth metatarsal 
 bones. 
 
 The phalanges of the toes are connected in all respects like those 
 of the fingers. See the description given in the dissection of the 
 hand (p. 306). 
 
 DISSECTION OF THE BEAlN. 
 
 Membranes Previous to the examination of the brain itself, we 
 of the brain, should study the structure and uses of the three mem- 
 branes by which it is surrounded. 
 
 The first, the 'dura mater,' has been described (p. 5). The 
 second is a serous membrane, termed the ' arachnoid ; ' the third is 
 a very vascular one, termed the ( pia mater.' 
 
 Arachnoid This second investment forms the smooth, polished 
 membrane, surface of the brain, exposed after the removal of the 
 dura mater. It is named 'arachnoid ' from the delicacy of its 
 texture, like a spider's web. It is a serous membrane, and, like 
 all others of the kind, forms a closed sac, one part of which, 
 the ' parietal ' layer, lines the under surface of the dura mater ; 
 the other, the ' visceral, ' is reflected over the brain : this re- 
 flection takes place along the nerves which leave the base of the 
 skull. 
 
 The inner surface of this membrane is perfectly smooth,, and 
 
512 DISSECTION OF THE BRAIN. 
 
 lubricated by a serous fluid to prevent friction ; since the brain 
 rises and falls with a slight pulsation, caused in part by the action 
 of the heart, in part by respiration. The parietal layer is so thin 
 that it cannot be demonstrated as a distinct layer ; it consists of 
 little more than a layer of squamous epithelium, lining the inner 
 aspect of the dura mater. But the visceral layer is obvious : 
 colourless and transparent, it is spread uniformly over the surface 
 of the brain, and does not dip into the furrows between the con- 
 volutions. On account of its extreme tenuity, and its close adhesion 
 to the pia mater, it cannot be readily separated from this membrane ; 
 but there are parts at the base of the brain, termed ' sub-arachnoid ' 
 spaces, where the arachnoid membrane can be seen distinct from 
 the subjacent tissue. 
 
 Sub-arachnoid ^ ne aracnn i ( i membrane is separated in certain 
 spaces and situations from the pia mater by a serous fluid (cerebro- 
 spinal) contained in the meshes of very delicate areolar 
 tissue. Such spaces are called ' sub-arachnoid? There is one in 
 the longitudinal fissure of the cerebrum, where the arachnoid does 
 not descend to the bottom, but passes across below the edge of the 
 falx, a little above the corpus callosum. At the base of the brain 
 there are two of considerable size : one, the ' middle sub-arachnoid 
 space,' is situated between the pons Varolii and the commissure of 
 the optic nerves ; the other, the ' posterior,' is situated between the 
 cerebellum and the medulla oblongata. In the spinal cord, also, 
 there is a considerable interval between the arachnoid and the pia 
 mater occupied by fluid. The purpose of this fluid is, not only to 
 fill up space, like fat in other parts, but mechanically to protect the 
 nervous centres from the violent shocks and vibrations to which 
 they would otherwise be liable. 
 
 The base of the brain may, in truth, be said to be supported by 
 abed of fluid, which insinuates itself into all the inequalities of the 
 surface, and surrounds all the nerves down to the foramina, through 
 which they pass. This fluid sometimes escapes through the ear, 
 in cases of fracture through the base of the skull, involving the 
 meatus auditorius internus and the petrous portion of the temporal 
 bone. 
 
MEMBRANES OF THE BRAIN. 513 
 
 This, the immediate investing membrane of the 
 
 Pia mater. 
 
 brain, is extremely vascular ; and composed of a net- 
 work of blood vessels held together by the finest connective tissue. 
 From its internal surface, small branches pass off at right angles 
 into the interior of the brain. Thepia mater dips into the fissures 
 between the convolutions, and penetrates into the ventricles for 
 the supply of their interior, forming the ' velum interpositum ' 
 and the ' choroid plexuses.' 
 
 The brain is supplied with blood by the two internal 
 
 the te brain f carotid and the two vertebral arteries. 
 
 This artery enters the skull through the carotid canal 
 Internal j n the temporal bone, and mounts up very tortuously 
 by the side of the body of the sphenoid, along the inner 
 wall of the cavernous sinus. It appears on the inner side of the 
 anterior clinoid process, and, after giving off the ophthalmic, 
 divides into the anterior and middle cerebral, and the posterior 
 communicating arteries. 
 
 a. The anterior cerebral artery sinks into the longitudinal 
 fissure between the hemispheres, curves round the front part of 
 the corpus callosum, and then runs backwards along its upper 
 surface (under the name of artery of the corpus callosum), and 
 terminates in branches which anastomose with the posterior 
 cerebral. The anterior cerebral arteries of opposite sides run 
 close together; and at the base of the brain are connected by a 
 transverse branch, called the f anterior communicating artery ' 
 (fig. 119). 
 
 6. The middle cerebral artery, the largest branch of the internal 
 carotid, runs deep in the fissure of Sylvius, and divides into many 
 branches, distributed to the anterior and middle lobes. Near its 
 origin it gives off a multitude of little arteries, which pierce the 
 locus perforatus anticus to supply the corpus striatum. 
 
 c. The posterior communicating artery proceeds directly back- 
 wards to join the posterior cerebral; thus establishing at the base 
 of the brain the free arterial inosculation called the ' circle of 
 Willis.' 
 
 d. The anterior choroid artery, a small branch of the internal 
 
 L L 
 
514 
 
 DISSECTION OF THE BRAIN. 
 
 carotid, arises external to the posterior communicating artery. It 
 runs backwards, and terminates in the choroid plexus of the lateral 
 ventricle. 
 
 This artery, a branch of the subclavian, winds back- 
 wards along the arch of the atlas, and enters the skull 
 through the foramen magnum, curving round the 
 
 Fig. 119. 
 
 Vertebral 
 artery. 
 
 Bulb of olfactory nerve 
 
 Second pair or optic 
 nerve 
 
 Locus perf oratus anticus. 
 Tractus opticus .... 
 
 Cms cerebri 
 
 Third pair of nerves . . 
 Fourth pair of nerves 
 Fifth pair of nerves . . 
 Sixth pair of nerves . . 
 
 Pyramid 
 Olive . 
 
 Vertebral artery 
 Anterior spinal a. 
 
 Anterior cerebral a. 
 
 Lamina cinerea. 
 Middle cerebral a. 
 
 ber cinereum. 
 Mammillary body. 
 Locus perf oratus medii 
 Posterior cerebral a. 
 
 perior cerebellar a. 
 Pons Varolii. 
 Inferior cerebellar a. 
 enth pair of nerves 
 
 Eighth pair of nerves. 
 .Ninth pair of nerves. 
 
 Cerebellum. 
 
 medulla oblongata between the hypoglossal nerve, and the anterior 
 root of the first cervical. At the lower border of the pons, the 
 two arteries unite to form the f basilarj which proceeds along the 
 
CIRCLE OP WILLIS. 515 
 
 middle of the pons, and divides at its upper border into the two 
 posterior cerebral arteries. 
 
 Each vertebral artery before joining its fellow gives off 
 
 a. A posterior meningeal branch distributed to the posterior 
 fossa of the skull. 
 
 b. Anterior and posterior spinal arteries, which supply the 
 front and back surfaces of the spinal cord. 
 
 c. The inferior cerebellar artery, sometimes a branch of the 
 basil ar, but more frequently of the vertebral, passes backwards, and 
 supplies the lower surface of the cerebellum. 
 
 The basilar artery, formed by the junction of the two vertebral, 
 in its course along the pons gives off on each side 
 
 a. Transverse branches which pass outwards on the pons : one, 
 the auditory, enters the meatus auditorius internus with the 
 auditory nerve ; another, the anterior cerebellar, supplies the front 
 part of the lower surface of the cerebellum. 
 
 b. The superior cerebellar, which supplies the upper surface of 
 the cerebellum. 
 
 c. The posterior cerebral, the terminal branches, run outwards 
 and backwards, one on the under surface of each posterior cerebral 
 lobe, and divide into numerous branches, which ultimately inos- 
 culate with the outer cerebral arteries. Each gives off a small 
 posterior choroid artery distributed to the choroid plexus. 
 
 This important arterial inosculation (fig. 119) is 
 WTlis f formed, laterally, by the two anterior cerebral, the two 
 internal carotid, and the two posterior communicating 
 arteries : in front it is completed by the anterior communicating 
 artery ; behind, by the two posterior cerebral. The tortuosity of 
 the large arteries before they enter the brain is intended to miti- 
 gate the force of the heart's action; and the circle of Willis 
 provides a free supply of blood from other quarters, in case any 
 accidental circumstance should stop the flow of blood in any of the 
 more direct channels.* 
 
 * In many of the long-necked herbivorous quadrupeds a beautiful provision has 
 been made, in the disposition of the internal carotid arteries, for the purpose of 
 equalising the force of the blood supplied to the brain. The arteries, as they enter 
 
 L L 2 
 
516 DISSECTION OF THE BRAIN. 
 
 Besides the f circle of Willis,' there are other pecu- 
 of the cere- liarities in the circulation of the brain ; namely, the 
 bral circula- tortuosity of the four great vessels as they enter the 
 skull their passage through bony canals their 
 breaking up into minute arteries in the pia mater before they 
 enter the substance of the brain the formation of sinuses (p. 6) 
 the great minuteness of the capillaries, and the extreme thinness 
 of their walls ; a fact which accounts for the slowness with which 
 a congested brain recovers itself. 
 
 GENERAL DI- mass ^ nervous matter contained within the 
 
 VISION OF skull, designated under the common term brain, is 
 THE BRAIN, ^y^d j n ^ o three parts the ' cerebrum,, or intellectual 
 brain, which occupies the whole of the upper part of the cranial 
 cavity; the ' cerebellum,' or little brain, which occupies the lower 
 and back part beneath the tentorium; the 'pans VaroliiJ or 
 quadrilateral mass of white fibres, which rests upon the basilar 
 process ; and the ' medulla oblongataS situated beneath the cere- 
 bellum. This last part passes out of the skull through the foramen 
 magnum, and is continuous with the spinal cord. 
 
 The size of the brain varies in different subjects, but in an adult 
 male the average weight is about 48 ounces ; in an adult female, 
 about 43 ounces.* 
 
 This term is applied to that part of the cerebro- spinal 
 ax * s WD i c h * s situated immediately below the pons 
 Varolii, and is continuous below with the spinal cord. 
 Its form is pyramidal with the broadest part above; thence it 
 gradually tapers into the spinal cord. It is about an inch and a 
 quarter long, and nearly an inch in its thickest part. It lies on 
 the basilar groove of the occipital bone, and descends obliquely 
 
 the skull, divide into several branches, which again unite, so as to form a remarkable 
 network of arteries, called by Galen, who first described it, the ' rete mirabile.' The 
 object of this evidently is to moderate the rapidity with which the blood would other- 
 wise enter the cranium, in the different positions of the head, and thus preserve the 
 brain from those sudden influxions to which it would under other circumstances be 
 continually exposed. 
 
 * Dr. E. Boyd, Philos. Trans., 1860. 
 
MEDULLA OBLONGATA. 
 
 517 
 
 backwards through the foramen magnum to the upper border of 
 the atlas, where it is continuous with the spinal cord. Its posterior 
 surface is received into the fossa between the hemispheres of the 
 cerebellum. In front and behind, the medulla is marked by a 
 median fissure the anterior and posterior median fissures, which 
 are the continuations upwards of the median fissures of the spinal 
 cord. The anterior terminates below the pons Varolii in a cul-de- 
 
 Fig. 120. 
 
 1. Gasserian ganglion. 
 
 2. Motor root of the 
 
 fifth n. 
 
 3. Third n. 
 
 4. Arciform fibres. ; 
 
 5. Sensitive root of 
 
 the fifth n. 
 
 6. Sixth n. 
 
 P. V. Pons Varolii. 
 P. Anterior pyramid. 
 O. Olive. 
 
 R. Restiform tract 
 or body. 
 
 7. Two divisions of 
 
 the seventh n. 
 
 8. Three divisions of 
 
 the eighth n. 
 
 9. Ninth or hypoglos- 
 
 DIAGBAM OP THE FEONT SUEFACE OF THE MEDULLA OBLONGATA. 
 
 sac, named * foramen ccecum-,' it is occupied by a fold of pia 
 mater. On each half of the medulla, there stand out, in relief, 
 four longitudinal columns. Those nearest to the anterior fissure 
 are called the ' anterior pyramids. 1 External to these are the 
 * olivary bodies.' Still more external, and towards the posterior 
 part of the medulla, are the ' restiform bodies ; ' lastly, on each 
 side of the posterior median fissure, are the ( posterior pyramids.' 
 The anterior pyramids are narrow below, but gradually increase 
 in breadth as they ascend towards the pons, from which they are 
 separated by a transverse groove. Their component fibres are 
 
518 DISSECTION OF THE BRAIN. 
 
 continuous with the anterior columns of the spinal cord, and 
 consist therefore of motor fibres. They may be traced through 
 the pons into the lower part of the crura cerebri. By gently sepa- 
 rating the pyramids about an inch below the pons, you observe 
 that their fibres on each side decussate (fig. 120). This is the ex- 
 planation of ' cross paralysis ; ' i. e. when one side of the brain is 
 injured, the loss of motor power is manifested on the opposite side 
 of the body.* The decussation, consisting of three or four bundles 
 of fibres on each side, takes place only between the inner fibres of 
 the pyramid ; the outer fibres run straight on without crossing over. 
 These decussating fibres are prolongations of the deep fibres of the 
 lateral columns of the cord, which here come forward to the sur- 
 face, pushing aside the proper anterior columns. 
 
 The olivary bodies are two oval eminences situated on the outer 
 side of the anterior pyramids, and separated from the pons by a 
 deep groove. They consist, externally, of white substance ; when 
 cut into, their interior presents a zigzag line of grey matter, called, 
 from its shape, ( corpus dentatum.' This grey line forms a circuit, 
 interrupted only on the upper and inner side, so that it nearly 
 isolates the white matter in its centre. Arching round its lower 
 part some white fibres may be observed : these constitute the 
 arciform fibres of Rolando. 
 
 The restiform bodies are situated on the outer side of and 
 behind the olives. They are the continuations upwards of the 
 posterior columns of the cord, and as they ascend, diverge from 
 each other and pass into the cerebellum, constituting its inferior 
 crura (p. 519). In consequence of this divergence, the grey matter 
 in the interior of the medulla oblongata is exposed ; so that the 
 floor of the fourth ventricle (of which the restiform bodies assist in 
 forming the lateral boundaries) is grey. The restiform bodies 
 consist partly of longitudinal white fibres derived from the posterior 
 and lateral columns of the cord ; partly of grey matter contained 
 
 * The phenomenon of ' cross paralysis ' of sensation is explained by the fact made 
 out by Brown Sequard, that the paths of sensory impressions cross each other in the 
 grey matter of the cord. 
 
MEDULLA OBLONGATA. 
 
 519 
 
 in their interior, which is continuous with that in the posterior part 
 of the spinal cord. 
 
 The posterior pyramids are two slender white bundles placed 
 on each side of the posterior median fissure (fig. 121). They pass 
 upwards and then diverge from each other, forming the apex of 
 the fourth ventricle. They proceed with the restiform bodies for 
 some distance, leaving which, they are lost in the cerebrum. At 
 
 Fig. 121. 
 
 DIAGRAM OF THE FOURTH VENTRICLE AND RESTIFORM BODIES. 
 
 1. Thalamus options. 
 
 2. Nates and testes. 
 
 3. Origin of fourth nerve. 
 
 4. Processns a cerebello ad testes. 
 
 5. Restiform bodies diverging. 
 
 6. Origin of seventh or auditory nerve. 
 
 their point of divergence the posterior pyramids become slightly 
 enlarged, forming what is called the ( processus clavatus.' 
 
 When a longitudinal section is carefully made through the 
 middle of the medulla oblongata, a number of white fibres are seen 
 running in a horizontal direction, constituting a kind of septum 
 between the two halves. Some of these septal fibres issue from the 
 anterior median fissure, wind round the medulla, and constitute 
 what are termed the arciform fibres of Eolando (p. 517); others, 
 issuing from the posterior fissure, wind round in a similar manner, 
 
520 DISSECTION OF THE BRAIN. 
 
 and form some of the transverse fibres seen on the floor of the 
 fourth ventricle. 
 
 PonsVarolii *^ n * s convex eminence (p. 517) is situated at the 
 or tuber base of the brain, immediately above the medulla ob- 
 annulare. longata. It corresponds with the basilar groove of the 
 occipital bone. In its antero-posterior diameter it measures rather 
 more than an inch. Down the middle runs a slight groove which 
 lodges the basilar artery. If the pia mater be carefully removed, 
 we observe that its superficial fibres proceed transversely from one 
 
 hemisphere of the cerebellum to the other, forming the 
 commissure great commissure or middle peduncles of the cerebellar 
 of the cere- lobes. Throughout the mammalia its size bears a direct 
 
 ratio to the degree of development of these lobes ; there- 
 fore it is larger in man than in any other animal."* The super- 
 ficial fibres only are transverse ; if these be removed, we see that 
 the anterior fibres of the medulla run under them at right angles 
 into the crura cerebri, like a river under a bridge. 
 
 The pons, like the medulla oblongata, has an imperfect median 
 septum, composed of horizontal fibres, which come from the floor 
 of the fourth ventricle. 
 
 Besides the transverse and longitudinal fibres just described, 
 the pons contains grey matter, which probably gives origin to fresh 
 nerve fibres ; so that the pons may be considered a source, as well 
 as a conductor of power. 
 
 The cerebrum, in man, is so much more developed 
 
 than the other parts of the brain, that it completely 
 overlays them. It is of an oval form and convex on its external 
 aspect. It is divided in the middle line by the deep ( Longitudinal 
 fissure ' into two equal halves, termed the right and left hemi- 
 spheres, f The fissure is occupied by the falx cerebri (p. 5). The 
 t 
 
 * Birds, reptiles, and fishes have no pons, because there are no lateral lobes to the 
 cerebellum. 
 
 f Examples are now and then met with where the longitudinal fissure is not exactly 
 in the middle line ; the consequence of which want of symmetry is, that one hemi- 
 sphere is larger than the other. Bichat (Recherches Physiologiques sur la Vie et la 
 Mort, Paris, 1829) was of opinion that this anomaly exercised a deleterious influence 
 on the intellect. It is remarkable that the examination of his own brain after death, 
 went to prove the error of his own doctrine. 
 
MEDULLA OBLONGATA. 521 
 
 surface of each hemisphere is mapped out by tortuous eminences, 
 termed ' gyri' or 'convolutions,' separated from each other by 
 deep furrows (sulci). Many of these furrows are occupied by the 
 large veins in their course to the sinuses ; others are filled by sub- 
 arachnoid fluid. The convolutions themselves are merely folds 
 of the brain, for the purpose of increasing the extent of the 
 surface upon which may be laid grey or vesicular nerve substance, 
 now generally admitted to be the source of power. They are not 
 precisely alike on both sides. Their number, disposition, and 
 depth vary a little in different individuals, and, to a certain extent, 
 may be considered as an index of the degree of intelligence.* 
 Since this grey matter forms a sort of bark round the white brain 
 substance, it is often called the cortical substance.f The depth 
 of the sulci between the convolutions varies in different subjects ; 
 generally they penetrate to about an inch : hence it follows that 
 two brains of apparently equal size may be very unequal in point 
 of extent of surface for the grey matter, and therefore in amount of 
 intellectual capability. Under the microscope, the cortical layer is 
 seen to consist of four layers, two grey alternating with two of white; J 
 
 * Those who wish to investigate the cerebral convolutions in their simplest form in 
 the lower classes of mammalia, and to trace them through their successive complica- 
 tions and arrangement into groups as we ascend in the higher classes, should consult 
 M. Leuret, Anatomic Comparee du Systeme Nerveux considered dans ses Eapports 
 avec 1'Intelligence : Paris, 1839; also M. Foville, Traite de I'Anat.-du Systeme Ner- 
 veux, &c. : Paris, 1844. 
 
 f There are two kinds of nervous matter the grey or vesicular, and the white or 
 fibrous. The grey is exceedingly vascular, and contains the nerve vesicles, which are 
 generally allowed to be the source of power. The white consists of extremely delicate 
 nerve fibres, is scantily provided with blood vessels, and is probably the mere con- 
 ductor of power. 
 
 The intense vascularity of the grey matter has been demonstrated by Mr. Quekett 
 and Mr. Smee, who have had the kindness to allow the author to inspect their beau- 
 tiful preparations. Mr. Smee's injections were made by using a solution of carmine in 
 ammonia mixed with size. The minute arteries enter the surface of the grey matter, 
 and break up in it into a network of fine capillaries. These capillaries are peculiar in 
 being quite naked, and not supported, as in other parts, by cellular tissue. Hence it is 
 they are so liable to give way, and allow their contents to escape : hence it is, they 
 are fenced round by so many provisions calculated to break the force of the current of 
 the blood namely, the tortuosities of the arteries at the base of the brain, their sub- 
 divisions in the pia mater, and the peculiar arrangement of the sinuses. 
 
 | Six layers may be demonstrated in some situations, chiefly near the corpus cal- 
 
522 DISSECTION OF THE BRAIN. 
 
 the external layer being always white. Some of these convolutions 
 from their size and regularity have received special names. The 
 most important are as follow : 
 
 a. The gyrus fornicatus, or the convolution of the corpus callo- 
 sum, commences close to the optic commissure, and curving along 
 the free surface of the corpus callosum, winds round its posterior 
 extremity, and terminates in the middle lobe forming the hippo- 
 campus major. 
 
 b. The margined convolution, or the convolution of the longi- 
 tudinal fissure, begins in the posterior part of the anterior lobe, 
 courses along the margin of the fissure, and after a tortuous course 
 is lost on the under surface of the middle lobe. 
 
 c. The island of ReiL This may be seen by separating the 
 middle from the anterior lobe, deep in the fissure of Sylvius. It 
 is composed of a number of small convolutions connected with 
 those adjoining. It corresponds to the under surface of the corpus 
 striatum, and might, therefore, be called the lobe of that ganglion. 
 
 The under surface of each cerebral hemisphere is not only con- 
 voluted like the upper, but presents in addition three lobes 
 
 (fig. 122), an anterior, middle, and pos- 
 !% 122. terior, which fit into the base of the skull. 
 
 The anterior lobe, triangular in shape, 
 rests upon the roof of the orbit, and is 
 separated from the middle by a cleft 
 called the 'fissure of Sylvius, 1 which 
 receives the lesser wing of the sphenoid 
 bone. The middle lobe occupies the 
 middle fossa of the skull, formed by the 
 sphenoid and temporal bones. The pos- 
 i, 2, s. Anterior, middle, and poste- teriw lobe rests on the arch of the tento- 
 
 rior lobes of the cerebrum. . . 
 
 4. cerebellum. rium. Between this and the middle there 
 
 is no definite Boundary, so that some 
 anatomists enumerate only two lobes. 
 
 losum. For an account of these laminae, and the best mode of examining them, see 
 Baillarget, Kecherches sur la Structure de la Couche Corticale des Circonvolutions du 
 Cerveau, inse'rees dans les Memoires de 1'Academie de M&lecine, 1 840. 
 
NOMENCLATURE OP PARTS AT BASE OF BRAIN. 523 
 
 The several objects seen at the base of the brain in 
 of the part* t^ 6 middle line should now be examined, proceeding in 
 at the base order from the front (fief. 119, p. 514). In this de- 
 
 of the brain. . .. ,, , , x ../ , __, .,, 
 
 scription the cerebral nerves are omitted. These will 
 be examined hereafter. 
 
 In the middle line dividing the anterior lobes is the longitudinal 
 fissure. By gently separating the anterior lobes, we expose the 
 anterior extremity of the corpus callosum, or the great transverse 
 commissure which connects the two hemispheres of the cerebrum. 
 Continued backwards and outwards on each side from the corpus 
 callosum to the fissure of Sylvius, is a white band, called the 
 peduncle of the corpus callosum. Extending from the corpus 
 callosum to the optic commissure is a layer of grey matter, lamina 
 cinerea, which is continued backwards to the tuber cinereum. Be- 
 tween the anterior and middle lobes is a deep fissure, ( the fissure 
 of Sylvius J at the bottom of which are situated the middle cerebral 
 artery and the island of Eeil. The optic commissure, formed by 
 the union of the two optic tracts, is seen in the middle line behind 
 the lamina cinerea. At the root of the fissure of Sylvius, and in 
 front of the optic tract, is a space, the locus perforatus anticus, 
 the surface of which is perforated by small blood vessels, which 
 supply the corpus striatum. Immediately behind the optic com- 
 missure is a simple elevation of the surface, consisting of grey 
 matter, called the ' tuber cinereum. 9 From this a conical tube of 
 reddish colour, termed the ( infundibulum.j descends to the 
 ( pituitary body, which occupies the sella turcica of the sphenoid 
 bone. The pituitary body consists of two lobes, the anterior and 
 larger is of a reddish-brown colour, and concave behind to receive 
 the posterior lobe. On section, it is composed of a soft pulpy 
 mass of a yellowish-brown colour. Behind the tuber cinereum, 
 are two round white bodies, the ( corpora mammillaria or 
 albicantia? which are formed by the curling round of the anterior 
 horns of the fornix. Between the mammillary bodies and the 
 pons is a depression of grey matter called the locus perforatus 
 posticus or pons Tarini, the surface of which is pierced by small 
 vessels supplying the optic thalami. From the anterior border of 
 
524 
 
 DISSECTION OF THE BRAIN. 
 
 the pons, two round cords of white nervous matter, about half an 
 inch thick, diverge from each other, one towards each hemisphere 
 of the cerebrum. These are the crura cerebri. Winding round 
 the outer side of each crus is a soft white band, the 'tractus 
 options,' or root of the optic nerve. 
 
 Fig. 123. 
 
 1. Olfactory n. 
 
 2. Optic n. 
 
 3. Crus cerebri. 
 
 4. Section of crus to 
 
 show locus niger. 
 
 5. Corpus geniculatum 
 
 externum. 
 
 6. Corpus geniculatum 
 
 internum. 
 
 7. Corpora quadri- 
 
 gemina. 
 
 8. Thalamus opticua. 
 
 9. Tractus opticus. 
 10. Corpus callosum. 
 
 DIAGRAM OF THE ORIGINS OF THE OLFACTORY AND OPTIC NERVES. 
 
 ORIGIN OF The cere bral nerves are given off in pairs, named 
 
 THE CEREBRAL the first, second, third, &c., according to the order in 
 which they appear, beginning from the front. There 
 are nine pairs. Some are nerves of special sense as the olfactory, 
 the optic, the auditory ; others are nerves of common sensation 
 as the large root of the fifth, the glosso-pharyngeal, and the pneumo- 
 gastric; others, again, are nerves of motion as the third, the 
 fourth, the small root of the fifth, the sixth, the facial division of 
 the seventh, the spinal accessory, and the ninth. 
 First air or The lf ac t r y nerve is triangular, and fits into a 
 olfactory furrow between the convolutions. It proceeds straight 
 forwards under the anterior lobe, and terminates in 
 
ORIGIN OF THE CEREBRAL NERVES. 525 
 
 the olfactory ganglion, which lies on the cribriform plate of the 
 ethmoid bone. 
 
 The olfactory ganglion is olive-shaped, of a reddish-grey colour 
 and very soft consistence, due to a large amount of grey matter 
 contained in it. It gives off from its under surface the true ol- 
 factory nerves.* For the description of these, see p. 199. 
 
 This nerve arises by three roots an outer and an inner 
 composed of white matter, and a central composed of grey 
 (p. 524). 
 
 The outer root passes forwards as a thin white line from the 
 bottom of the fissure of Sylvius, and describes a curve with the 
 concavity outwards. 
 
 The inner root arises from the posterior extremity of the in- 
 ternal convolution of the anterior cerebral lobe. 
 
 The middle or grey root arises from the posterior extremity of 
 the furrow in which the olfactory nerve is lodged ; to see it, there- 
 fore, the nerve should be turned backwards. It contains white 
 fibres in its interior which have been traced to the corpus 
 striatum. 
 
 These nerves proceed from the optic commissure, 
 formed by the union of the two optic tracts. These 
 tracts arise from the corpora quadrigemina, the corpora 
 geniculata, and the optic thalami (p. 524 j. They wind round the 
 crura cerebri, to which they are connected by their anterior 
 borders, and join in the middle line to form the optic commissure. 
 This commissure rests on the sphenoid bone in front of the sella 
 turcica. From the commissure each optic nerve, invested by its 
 
 * Strictly speaking, the olfactory nerve and its ganglion are integral parts (the 
 prosencephalic lobe) of the brain. What in human anatomy is called the origin of 
 the nerve is, in point of fact, the cms of the olfactory lobe, and is in every way homo- 
 logous to the crus cerebri or cerebelli. In proof of this, look at the enormous size and 
 connections of the crus in animals which have very acute sense of smelL Throughout 
 the vertebrate kingdom there is a strict ratio between the sense of smell and the de- 
 velopment of the olfactory lobes. Again, in many animals, these lobes are actually 
 larger than the cerebral, and contain in their interior a cavity which communicates 
 with the lateral ventricles. According to Tiedemann, this cavity exists even in the 
 human foetus at an early period. 
 
526 DISSECTION OF THE BRAIN. 
 
 fibrous sheath, passes through the optic foramen into the orbit, 
 and terminates in the retina. 
 
 At the commissure some of the nerve fibres cross from one side 
 to the other. This decussation affects only the middle fibres of 
 the nerve ; the outer fibres pass from one optic tract to the optic 
 nerve of the same side ; the inner fibres pass from one optic tract 
 round to the optic tract of the opposite side ; while in front of 
 the commissure are fibres which pass from one optic nerve to its 
 fellow (p. 529). The purpose of this partial crossing is not 
 thoroughly understood. It was ingeniously supposed by Dr. 
 Wollaston* to account for single vision, since the right halves and 
 the left halves of the eyes would derive their nerve fibres from the 
 same optic nerve. 
 
 Third pair or ^ e apparent origin of the third nerve is from the 
 motores inner side of the crus cerebri, immediately in front of 
 
 the pons. Some of its fibres, however, penetrate into 
 the crus as far as the locus niger, and others to the corpora quadri- 
 gemina, and valve of Vieussens (p. 524). It passes through the 
 sphenoidal fissure, and supplies all the muscles of the orbit, ex- 
 cept the superior oblique and the rectus externus. 
 
 The fourth nerve arises from the upper surface of 
 cT. ^ e va ^ ve f Vieussens (p. 519). It runs transversely 
 
 outwards, winds round the crus cerebri, enters the 
 orbit through the sphenoidal fissure, and supplies the superior 
 oblique muscle of the eye. 
 
 Fifth pair ^" ne ^^ nerve consists of two roots, both of which 
 
 or trigeminal arise apparently from the outer side of the pons Varolii 
 
 (p. 517); but their real origin is deeper. The smaller 
 and anterior of the two roots, consisting of motor fibres only, may 
 be traced into the pyramidal tract in the pons ; the posterior and 
 larger, consisting of purely sensitive fibres, may be traced to the 
 floor of the fourth ventricle, between the restiform tract and the 
 fasciculus teres. The nerve proceeds forwards over the apex of 
 the petrous portion of the temporal bone : here is developed upon 
 the sensitive root the great Gasserian ganglion. This root then 
 divides into three branches : the ophthalmic, which passes through 
 
 * Philos. Trans, of the Royal Society, 1824. 
 
ORIGIN OF THE CEREBRAL NERVES. 527 
 
 the sphenoidal fissure ; the superior maxillary, which passes 
 through the foramen rotundum ; the inferior maxillary, which 
 passes through the foramen ovale. They all confer common 
 sensibility upon the parts they supply, which comprise nearly the 
 entire head. The small motor root passes beneath the ganglion, 
 with which it has no connection, and accompanies the inferior 
 maxillary division, to be distributed to the muscles of mastication. 
 Sixth pair or ^he sixth nerve emerges from the groove between the 
 abducentes. p ns and the medulla (p. 517), with both of which it is 
 connected. Its deep origin has been traced to the floor of the fourth 
 ventricle. It leaves the skull through the sphenoidal fissure, and 
 supplies the rectus externus of the eye. 
 
 The seventh consists of two nerves, the portio dura, 
 P air - or muscu l ar nerve of the face, and the portio mollis, or 
 proper auditory nerve. The two nerves, of which the portio dura 
 is the more internal, arise apparently from the lower part of the 
 pons Varolii (p. 517). The deep origin of the portio dura is 
 stated to come from the restiform and olivary fasciculi of the me- 
 dulla. The real origin of the portio mollis is from the floor of the 
 fourth ventricle by several transverse white filaments, which 
 emerge from the median groove. The seventh pair enters the 
 meatus auditorius internus, where they are connected by several 
 filaments. For the further description of the portio dura, see 
 p. 194. The auditory nerve divides at the bottom of the meatus 
 auditorius internus into cochlear and vestibular branches which are 
 distributed to the internal ear. 
 
 . This comprises three nerves, the glosso-pharyngeal, 
 the pneumogastric, and the nervus accessories (p. 5 1 7 ). 
 The first two arise by several filaments from the restiform tract of 
 the medulla close to the olive, through which their fibres may be 
 traced to the grey matter in the floor of the fourth ventricle. The 
 nervus accessorius is composed of two parts, an upper or accessory 
 portion, which arises from the side of the medulla oblongata, 
 and a lower or spinal portion, which arises by a series of slender 
 filaments from the lateral tract of the spinal cord as low down 
 as the fifth or sixth cervical vertebra. The spinal portion ascends 
 
528 DISSECTION OF THE BRAIX. 
 
 behind the ligaruentum denticulatum, into the skull through the 
 foramen magnum, and joins the accessory part. The nervus 
 accessorius then passes through the foramen jugulare, with the 
 pneumogastric and glosso-pharyngeal. The glosso-pharyngeal is 
 distributed to the mucous membrane of the pharynx and the back 
 of the tongue (p. 193). The pneumogastric is distributed to the 
 pharynx, the larynx, the heart and lungs, the oesophagus and the 
 stomach. The nervus accessorius supplies the sterno-mastoid and 
 the trapezius. For the further description of these nerves, see 
 pp. 21, 194. 
 
 This nerve arises by several roots from the medulla 
 oblongata, along the groove between the anterior 
 pyramid and the olive. Its fibres may be traced to the 
 grey matter in the floor of the fourth ventricle. It leaves the 
 skull through the anterior condyloid foramen, and is distributed 
 to the muscles of the tongue and the depressors of the os-hyoides 
 and larynx. 
 
 The brain should now be laid on its base. By gently 
 the^brain 1 se P ara -t m g the hemispheres, we expose at the bottom 
 
 of the longitudinal fissure a white band of nerve sub- 
 stance, which is the great transverse commissure of the cerebrum, 
 and termed the ' corpus callosum' 
 
 Slice off the hemispheres down to the level of the 
 
 cor P us callosum.* The cut surface presents a mass of 
 
 white substance surrounded by a tortuous layer of grey 
 matter, about one-eighth of an inch thick. This grey substance 
 consists of four layers two of grey alternating with two of white, 
 the most external layer being white. In some places, chiefly at 
 the base of the brain, six layers have been demonstrated. 
 
 This transverse portion of white substance is the chief 
 sum PUS Call " connec t m g medium between the two hemispheres, and 
 
 is called the great transverse commissure of the cere- 
 
 * The section of the brain at the level of the corpus callosum was called by the old 
 anatomists ' centrum ovale majus ; ' at a higher level, the section was called ' centrum 
 ovale minus.' 
 
CORPUS CALLOSUM. 
 
 529 
 
 brum.* It is about four inches long, and rather nearer to the 
 front than to the back part of the brain. Its surface is slightly 
 arched from before backwards. A shallow groove, called the 
 ' raphe? runs along the middle of its upper surface (fig. 124) ; in a 
 fresh brain, two white streaks, named the nerves of Lancisi, run 
 
 Fig. 124. 
 
 Fig. 125. 
 
 UPPER SURFACE OF COR- 
 PUS CALLOSUM. 
 
 1, 1. Lineae transversse. 
 
 2. Raphe. 
 
 3, 3. Anterior cerebral a. 
 
 DIAGRAM OF LAMINA CINEREA. 
 
 1,1. Peduncles of corpus caljosum. 
 
 2. Lamina cinerea. 
 
 3. Commissure of optic nerves. 
 
 parallel to it. The surface of the corpus callosum is marked by 
 transverse lines which indicate the course of its fibres: these are 
 the linece transversce of the old anatomists. The anterior cerebral 
 arteries proceed along the surface of the corpus callosum to the 
 back of the brain. 
 
 * In a brain properly hardened by spirit, the fibres may be traced congregating 
 towards the corpus callosum from both hemispheres : hence they were*called by Gall 
 the converging fibres of the brain. This anatomist applied the above name to all 
 commissural fibres. Those fibres, on the other hand, which ascended from the medulla 
 oblongata into the hemispheres, he named the diverging. Anat. et Physiol. du Sys- 
 teme Nerv. : Paris, 1810. 
 
 M M 
 
530 
 
 DISSECTION OF THE BRAIN. 
 
 The anterior part of the corpus callosum turns downwards and 
 backwards, forming a bend called its genu, or knee. The inferior 
 part (rostrum) of this bend becomes gradually thinner, and termi- 
 nates in two peduncles, which diverge from each other, and are 
 lost, one in each fissure of Sylvius. Between these crura is placed 
 the lamina cinerea (fig. 125). The posterior part of the corpus 
 callosum terminates in a thick, round border, beneath which the 
 
 Fig. 126. 
 
 Foramen of Monro 
 
 Middle commissure . 
 
 Anterior commissure. 
 Lamina cinerea . . 
 Optic nerve . . . 
 
 Pituitary gland 
 
 Infundibulum 
 Tuber cinerenm 
 
 Corpus mammillare 
 
 i 
 Locus perforatus posticus 
 
 Velum interpositurn. 
 Thalamus opticus. 
 Pineal gland. 
 Posterior commissure. 
 Nates. 
 
 Iter a tertio ad quar- 
 
 tum ventriculum. 
 Valve of Vieussentj. 
 
 Fourth ventricle. 
 
 Pons Varolii 
 
 Arachnoid membrane 
 (reflected). 
 
 Medulla oblongara 
 VERTICAL SECTION THROUGH THE CORPUS CALLOSUM, AND PARTS BELOW. 
 
 pia mater enters the interior of the ventricles. A satisfactory 
 view cannot be obtained of the arch formed by the corpus callo- 
 sum, of its terminations in front and behind, and of the relative 
 thickness of its different parts, without making a perpendicular 
 section through a fresh brain, as shown in the diagram.* 
 
 ^ * The corpus callosum is more or less developed in all mammalia, but is absent in 
 birds, reptiles, and fish. It is not absolutely essential to the exercise of the intellect, 
 
LATERAL VENTRICLES. 531 
 
 The two cavities called the ' lateral ventricles' are 
 ventricles situated, one in each hemisphere of the brain, beneath 
 the corpus callosum. A longitudinal incision should 
 be made on each side, about half an inch from the raphe of the 
 corpus callosum. Care must be taken not to cut too near the 
 middle line, in order to preserve the delicate partition which de- 
 scends from the under surface of the corpus callosum, and separates 
 the ventricles from each other. They should be laid open through- 
 out their whole extent. Their general form should be first ex- 
 amined ; afterwards the several objects contained in them. 
 
 The lateral ventricles are two cavities in the general mass of the 
 brain, occasioned by the enlargement and folding backward of the 
 cerebral lobes over the other parts of the central nervous axis. 
 They are lined with a ciliated spheroidal epithelium, and contain a 
 serous fluid, which, even in a healthy brain, sometimes exists in 
 considerable quantity : when greatly in excess, it constitutes one 
 form of the disease termed ' hydrocephalus.' 
 
 The ventricles are crescentic in shape, with their backs towards 
 each other. Each extends into the three lobes of the cerebral 
 hemisphere, and consists of a central part or body, and three horns, 
 or cornua, anterior, middle, and posterior. The body, situated in 
 the middle of the hemisphere, is separated from its fellow by the 
 septum lucidum. Its roof is formed by the corpus callosum ; and 
 on the floor, beginning from the front, are seen, the corpus striatum, 
 the taenia semicircularis, the optic thalamus, the choroid plexus, 
 and the fornix. The anterior horn extends into the anterior lobe, 
 and as it passes forwards, slightly diverges from its fellow on the 
 opposite side. The posterior horn may be traced into the posterior 
 lobe, where it passes at first backwards and outwards, and then 
 converges towards its fellow. In it take notice of an elevation of 
 white matter, the ' hippocampus minor ; ' also of a triangular flat 
 surface, called * pes accessorius ' or ' eminentia collateralis.'* The 
 
 for it has been found absent in the human subject without any particular intellectual 
 deficiency. See cases recorded by Eeil, Archiv. fur die Phys. t. xi. ; and Wenzel, de 
 plenitior Struct. Cereb. p. 302. 
 
 * The posterior horns are not always equally developed in both hemispheres, and 
 
 M M -2 
 
532 
 
 DISSECTION OF THE BRAIN. 
 
 middle horn runs into the middle lobe, descends towards the base 
 of the brain, making a very curious curve, like a ram's horn that 
 is, in a direction backwards, outwards, downwards, forwards, and 
 inwards ; the initial letters of which make the memorial word 
 ' bodfi.' By cutting through the substance of the middle lobe, the 
 windings of this horn can be followed ; in it are the hippocampus 
 major, the pes hippocampi, the posterior cms of the ibrnix, the 
 choroid plexus, and the thalamus opticus. 
 
 Fig. 127. 
 
 1. Corpus callosum. 
 
 2. Lateral ventricle. 
 
 3. Third ventricle. 
 
 4. Corpus striatum. 
 
 5. Thalamus opticus. 
 
 6. Corpus mammil- 
 
 lare. 
 
 7. Choroid plexus. 
 
 8. Fornix. 
 
 9. Pituitary gland. 
 
 TRANSVERSE PERPENDICULAR SECTION THROUGH THE BRAIN. 
 
 Appearance 
 on perpen- 
 dicular sec- 
 tion. 
 
 letter T. 
 
 If a perpendicular section were made across the 
 middle of the brain, the lateral ventricles would appear 
 as represented in fig. 127. Together with the third or 
 middle ventricle, their shape slightly resembles the 
 Such a section shows well the radiating fibres of the 
 corpus callosum, the fornix, and the velum interpositum beneath 
 it ; also the beginning of the transverse fissure at the base of the 
 brain, between the crus cerebri and the middle lobe. 
 
 sometimes they are absent in one or in both. They are only found in the brain of 
 man and the quadrumana. 
 
 - In the carnivora, ruminantia, solipeda, pachydermata, and rodentia, the lateral 
 ventricles are prolonged into the largely developed olfactory lobes. This is the case 
 in the human foetus only at an early period. 
 
LATERAL VENTRICLES. 533 
 
 The contents of the lateral ventricles should now be examined 
 more in detail ; also the transparent septum (septum lucidum) by 
 which the two lateral ventricles are separated. 
 
 This body is so called because, when cut into, it 
 striatum presents alternate layers of white and grey matter.* It 
 is a much larger mass of grey substance than it appears 
 to be, for only a portion of it is seen projecting on the floor of the 
 ventricle. The intra-ventricular portion is pear-shaped, with the 
 large end forwards ; and when traced backwards, is found to taper 
 gradually to a point on the outside of the optic thalamus (p. 539). 
 The under part (extra- ventricular portion) of the corpus striatum 
 corresponds with the convolution at the base of the brain, known 
 as the island of Reil, and also with the locus perforatus anticus a 
 spot at the root of the fissure of Sylvius, so called on account of 
 the number and size of the blood vessels which pass in there to 
 supply the mass of grey matter in question. 
 
 This is a narrow semi-transparent band of longi- 
 Tsema semi- tudinal white fibres, which skirts the posterior border 
 
 circularis. t * 
 
 of the corpus striatum (tig. 129). In front it is con- 
 nected with the anterior crus of the fornix ; behind, it is lost in 
 the middle horn of the lateral ventricle. A large vein from the 
 corpus striatum passes underneath the taenia semicircularis to 
 join the vena Graleni. 
 
 This is a thin and almost transparent partition, which 
 Septum descends vertically in the middle line from the under 
 
 surface of the corpus callosum, and separates the an- 
 terior part of the lateral ventricles from each other. It is attached, 
 above, to the corpus callosum ; below, to the reflected part of the 
 corpus callosum and the fornix (p. 530). It is not of equal depth 
 throughout. The broadest part is in front, and corresponds with 
 the knee of the corpus callosum. It becomes narrower behind, 
 
 * The white lines in the corpus striatum are produced by the fibres of the crus 
 cerebri, which traverse this mass of grey matter before they expand to form the hemi- 
 sphere. The grey matter itself is sometimes called the anterior cerebral ganglion. It 
 is found in all mammalia, in birds, and, to a certain extent, in reptiles. Its precise 
 function is still unknown. 
 
534 
 
 DISSECTION OF THE BRAIN. 
 
 and disappears where the corpus callosum and the fornix become 
 continuous. The septum consists of two layers, which inclose a 
 space called the 'fifth ventricle ' (fig. 128). Each layer is made up 
 of white substance inside, and of grey outside ; the ventricle be- 
 tween them is closed in the adult, and lined by a delicate serous 
 membrane, which secretes in it a minute quantity of fluid ; but 
 in foetal life it communicates with the third ventricle between the 
 pillars of the fornix.* 
 
 Cut transversely through the corpus callosum and the septum 
 lucidum, and turn forwards the anterior half. In this way the 
 
 1,1. Corpora striata. 
 
 2, 2. Thalami optici. 
 
 3,3. interior crura 
 of fornix bend- 
 ing down to join 
 the corpora 
 mammillaria. 
 
 4. 4. Posterior crura 
 of the fornix 
 joining the hip- 
 pocampi. 
 
 5. 5. Choroid plexus. 
 
 6. 6. Hippocampi 
 
 majores. 
 
 7. Corpus callosum 
 
 cut through. 
 
 8. Fifth ventricle. 
 
 DIAGBAM OF THE FOKNIX. 
 
 (The arrow is in the foramen of Monro.) 
 
 ventricle of the septum will appear as in fig. 128. By turning 
 back the posterior half of the corpus callosum, a view is obtained 
 of the fornix. This proceeding requires care, or the fornix will be 
 reflected also, since these two arches of nervous matter are here so 
 closely connected. 
 
 This is a layer of white matter extending in the form 
 of an arch from before backwards, beneath the corpus 
 callosum. It is the 'great longitudinal commissure,' and lies 
 
 Fornix. 
 
 * The development of the septum lucidum commences about the fifth month of foetal 
 life, and proceeds from before backwards pari passu with the corpus callosum and 
 fornix. 
 
LATERAL VENTRICLES. 535 
 
 over the velum interpositum (fig. 126, p. 530). Viewed from its 
 upper surface, it is triangular, with the base behind, as shown in 
 diagram 128. The broad part or body is connected to the corpus 
 callosum. From its anterior narrow part proceed two round white 
 cords, called its anterior crura, one on each side of the mesial line. 
 As they pass forwards, the crura descend towards the base of the 
 brain, where, making a bend upon themselves, they form part of 
 the corpora mammillaria, from which they may be traced, passing 
 backwards to the optic thalami. Immediately behind, and below 
 the anterior crura, is a passage through which the choroid plexuses 
 of opposite sides are continuous with each other. This aperture 
 is called the 'foramen ofMonro* (fig. 126).* Strictly 
 speaking, it is not a foramen, but only a communication 
 existing between the two lateral and the third ventricles. 
 The posterior crura are continued downwards and outwards from 
 the body of the fornix, as thin white bands, intimately connected 
 with the concave side of the hippocampus major as far down as the 
 pes hippocampi. Each band is called the tcenia hippocampi, or 
 the corpus fimbriatum.} 
 
 This is an elongated mass of grey matter covered 
 Hippocampus witll w }^ ey an( j j s situated in the posterior part of the 
 descending horn. It extends to the bottom of the 
 horn, where it becomes somewhat expanded, and indented on the 
 surface, so as to resemble the paw of an animal ; whence its name, 
 ( pes hippocampi.' Attached along the front border of the 
 hippocampus, is the posterior crus of the fornix. 
 
 This mass, smaller than the preceding, is situated in 
 Hippocampus foe posterior horn. It consists of white matter ex- 
 
 minor. 
 
 ternally, and corresponds to a deep convolution which 
 projects into the ventricles. Between the hippocampus major and 
 minor, is a triangular smooth surface, called the pes accessorius, 
 or eminentia collateralis. 
 
 * Monro, 'Microscopic Enqxiiries into the Nerves and Brain.' Edinburgh, 1780. 
 . f The fornix and septum lucidum are absent in fish ; they are merely rudimentary 
 in reptiles and birds : but all mammalia hare them in greater or less perfection, 
 according to the degree of development of the cerebral hemispheres. 
 
536 DISSECTION OF THE BRAIN. 
 
 The fornix should now be cut through, and its two portions 
 reflected. On the under surface of the posterior portion is seen a 
 number of fibres arranged transversely, constituting what is termed 
 the lyra. 
 
 Between the fornix and the upper surface of the cerebellum is 
 the * transverse fissure, or fissure of BichatJ through which the 
 pia mater enters the ventricles. The fissure extends downwards 
 on each side to the base of the brain, and terminates between the 
 crus cerebri and the middle lobe. It is of a horse- shoe shape, 
 with the concavity directed forwards. 
 
 The velum interpositum. which supports the fornix, 
 
 Velum inter- _ _ , 
 
 positum and should now be examined. This is a portion of the pia 
 choroid mater, which penetrates into the ventricles through the 
 
 fissure of Bichat, beneath the posterior border of the 
 corpus callosum, as shown at p. 530. The shape of this vascular 
 veil is like that of the fornix, and its borders are rolled up so as to 
 form the red fringe called the ' choroid plexus.' These plexuses 
 consist almost entirely of the tortuous ramifications of minute 
 arteries.* In front, they communicate with each other through 
 the foramen of Monro ; behind, they descend with the middle horns 
 of the lateral ventricles, and become continuous with the pia 
 mater at the base of the brain, between the middle lobe of the 
 cerebrum and the crus cerebri. From the under surface of the 
 velum, two small vascular processes are prolonged into the third 
 
 ventricle forming the choroid plexuses of that cavity. 
 Venae Along the centre of the veil run two large veins, called 
 
 ( vence GaleniJ which return the blood from the ventri- 
 cles into the straight sinus. 
 
 The velum interpositum, with the choroid plexus, must now be 
 reflected to expose the following parts shown in diagram 129: 
 1. A full view of the thalamus opticus. 2. Between the thalami 
 optici is the ' third ventricle of the brain,' a deep vertical fissure, 
 situated in the middle line. 3. Behind the fissure is the 'pineal 
 
 * In preparations where the choroid plexus is well injected, we see that they are 
 covered with beautiful vascular villi. The villi themselves are covered with epi- 
 thelium. 
 
THALAMUS OPTICUS. THIKD VENTRICLE. 537 
 
 gland? a vascular body, about the size of a pea. From the gland 
 may be traced forwards two slender white cords, called its ' pedun- 
 cles ' one along the inner side of each optic thalamus. 4. Passing 
 transversely across are three commissures anterior, middle, and 
 posterior, connecting the opposite sides of the brain. 5. Immedi- 
 ately behind the pineal gland are four elevations, two on each 
 side, called the e corpora quadrigemina? or ( nates and testes? 
 
 6. These bodies are connected to the cerebellum by two bands, 
 one on each side, termed the 'processus a cerebello ad testes.' 
 
 7. Between these bands extends a thin layer of grey substance, 
 called the 'valve of Vieussens? beneath which lies the fourth 
 ventricle. 
 
 This is the oval elevation seen on the floor of the 
 opticus! US lateral ventricle, immediately behind the corpus stri- 
 atum and tsenia semicircularis. Though white on the 
 surface, its interior consists of alternate layers of white and grey 
 matter, like the corpus striatum.* The under surface of the 
 thalamus rests upon its corresponding crus cerebri, and forms the 
 roof of the descending or middle horn of the lateral ventricle. 
 Beneath the posterior part of the thalamus are two small emi- 
 nences, termed the 'corpus geniculatum internum, and ex- 
 ternum. These eminences are produced by small accumulations 
 of grey matter beneath the surface. A narrow band of white 
 matter connects the external one with the nates, and a similar 
 band connects the internal one with the testes.f 
 
 This is the narrow fissure which exists between the 
 Th \ rc ( , optic thalami, and reaches down to the base of the 
 
 ventricle. ' 
 
 brain. Its roof is formed by the velum interpositum ; 
 the floor, which increases in depth in front, by certain parts at the 
 
 * The elevation called the optic thalamus is occasioned by the interposition of a 
 quantity of grey matter among the fibres of the crus cerebri. Gall termed it the 
 inferior ganglion of the cerebrum, in opposition to the corpus striatum, which he 
 termed the superior ganglion (Anat. et Phys. du Systeme Nerv. : Paris, 1810). The 
 epithet ' optic ' applied to the thalamus might lead us to suppose that it presides over 
 vision ; but that it exercises very little influence over sight is rendered probable by 
 comparative anatomy, by experimental physiology, and by pathology. 
 
 f These bands are faintly marked in man, but more apparent in the lower animals. 
 
538 DISSECTION OF THE BRAIN. 
 
 base of the brain namely, the locus perforatus posticus, corpora 
 mammillaria, tuber cinereum, infundibulum, and lamina cinerea : 
 all of which are best seen in a vertical section, as shown p. 530. In 
 front it is bounded by the anterior crura of the fornix, and the 
 anterior commissure ; behind, it communicates with the fourth 
 ventricle through the ' iter a tertio ad quartum ventriculum ; ' 
 a long canal beneath the corpora quadrigemina. 
 
 By gently separating the optic thalami in a fresh 
 
 brain, you see that they are connected by a transverse 
 
 layer of grey matter about half an inch in breadth. This is the 
 
 middle commissure, sometimes called the soft, on 
 
 account of its delicate consistence : in most brains it is 
 
 generally torn before it can be examined.* The optic thalami 
 
 are also connected by a round white cord, called the 
 
 Posterior. , . T , . ., , , . , . , -, 
 
 posterior commissure. It is situated immediately in 
 front of, and rather below the pineal gland. The corpora striata 
 are connected by a round white cord, called the anterior 
 commissure: it lies immediately in front of the anterior 
 crura of the fornix. This commissure may be traced extending 
 transversely through the corpus striatum of each side ; then arch- 
 ing backwards, its fibres are lost near the surface of the middle 
 cerebral lobe. 
 
 The third ventricle communicates with the lateral ventricles 
 through the foramen of Monro, and with the fourth ventricle 
 through the iter a tertio ad quartum ventriculum. 
 
 This very vascular heart-shaped body is situated 
 ' immediately in front of the corpora quadrigemina. It 
 is wrapped up in the velum. It has two white peduncles or crura } 
 which extend forwards, one on the inner side of each optic thala- 
 mus, and terminate by joining the crura of the fornix. In its 
 interior is some gritty matter, consisting of phosphate of lime. 
 
 * The soft commissure does not appear to be a very essential constituent part of 
 the brain. It is not found before the ninth month of foetal life ; and in some instances, 
 according to our observation, is never developed. The brothers Wenzel state that it 
 is absent about once in seven subjects (De plenitiori Struct. Cerebri Horn, et Brut. 
 Tubingen, 1812). 
 
TUBERCULA QUADRIGEMINA, 
 
 539 
 
 Although the pineal gland is found in all mammalia, birds, and 
 reptiles, in the same typical position, its functions are entirely 
 unknown. 
 
 Corpus callosum cut through . 
 
 Ventricle of the septum lucidnm 
 Corpus striatum 
 Anterior crura of the fornix 
 Anterior commissure . . . 
 
 Taenia semicircularis 
 Middle commissure 
 
 Thalamus opticus 
 Crura of pineal gland 
 
 Posterior commissure 
 Pineal gland 
 Nates 
 Testes 
 
 Valve of Vieussens 
 
 Processus a cerebello ad testes . 
 
 Tubercula 
 
 These are four eminences, situated, two on each side, 
 Tubercuia t behind the pineal gland. Though white on the sur- 
 
 quadrigemina. 
 
 face, they contain grey matter in the interior: this 
 grey matter is accumulated here for the purpose of giving origin 
 to the optic nerve. A more appropriate term for them would be 
 the ( optic lobes,' instead of ' nates and testes,' handed down from 
 the old anatomists.* 
 
 * Eminences homologous to the corpora quadrigemina are found in all vertebrate 
 animals: they are the mesc-cephalic lobes; they invariably give origin to the optic 
 
540 DISSECTION OF THE BRAIN. 
 
 Processus a ^ S en ^7 drawing- back the overlapping cerebellum, 
 cerebello two broad white cords are seen, which pass backwards, 
 
 diverging from each other, from the corpora quadrige- 
 mina to the cerebellum (fig. 129). These are the 'superior 
 crura of the cerebellum? They[connect the cerebrum and the cere- 
 bellum. The space between them is occupied by a thin layer of 
 grey matter, which covers the fourth ventricle. This layer is called 
 the ' valve of VieussensJ The fourth'nerve arises from it by several 
 filaments. Two white bands proceed on each side from the cor- 
 pora quadrigemina to join the optic thalamus and the optic tract. 
 The third ventricle is connected with the fourth by 
 a? qiwrtirm me ans of a canal large enough to admit a probe, which 
 ventriculum, runs backwards beneath the posterior commissure and 
 of Sylvius the corpora quadrigemina (p. 530). This passage, to- 
 
 gether with the third and fourth ventricles, are per- 
 sistent parts of the central canal which, in early foetal life, extended 
 down the middle of the spinal cord. 
 
 This cavity is situated between the cerebellum and 
 ventricle ^ e posterior part of the medulla oblongata and pons 
 Varolii. It is only a dilated portion of the primordial 
 canal alluded to in the last paragraph. To obtain a perfect view 
 of its boundaries, a vertical section should be made, as in dia- 
 gram (p. 530). It appears triangular, and its boundaries are as 
 follow : The front or base is formed by the medulla oblongata 
 and pons Varolii ; the upper wall, by the valve of Vieussens and 
 the aqueduct of Sylvius ; the posterior wall, by the inferior vermi- 
 form process of the cerebellum ; below, by the continuation of the 
 arachnoid membrane on to the spinal cord ; and, laterally, by the 
 processus a cerebello ad testes, posterior pyramids, and restiform 
 bodies. The pia mater, is prolonged for a short distance into the 
 lower part of the cavity, and forms the ' choroid plexus of the 
 fourth ventricle.* 
 
 nerves, and their size bears a direct relation to the power of sight. They are relatively 
 smaller in man than in any other animal. In birds there are only two eminences, 
 and these are very large, especially in those far-seeing birds which fly high, as the 
 eagle, falcon, vulture, &c., who require acute sight to discern their prey at a distance. 
 * Tiedemann proposes to call the fourth ventricle the first ; because, in the foetus, it 
 
CALAMUS SCRIPTORIUS. CEREBELLUM. 541 
 
 The anterior wall of the fourth ventricle is lozenge- 
 sna P e d, and on it are the following objects, which 
 should be separately examined (p. 519): 1. A median 
 furrow, the remains of the primitive axis canal ; running parallel 
 to it on each side is a slight elevation, the fasciculus teres. 2. 
 From the lower part of the furrow two white cords (the restiform 
 columns or inferior crura cerebelli) pass off from the medulla 
 oblongata, diverging like the branches of the letter V, and enter 
 the lateral lobes of the cerebellum. The divergence of these cords 
 with the median furrow was called by the old anatomists the * cala- 
 mus scriptorius.'' 3. The floor of the fourth ventricle is covered 
 by grey matter, which is the grey substance of the medulla exposed 
 by the divergence of its posterior or restiform columns : one mass, 
 placed external to the fasciculus teres, has received the name of 
 ' locus cceruleusS 4. On its anterior surface are seen a number of 
 transverse white lines, emerging from the median groove, some of 
 which form part of the origin of the auditory nerves. 
 
 This portion of the brain is situated in the occipital 
 ' fossa, beneath the posterior lobes of the cerebrum, from 
 which it is separated by the tentorium. Its form is elliptical, 
 with the broad diameter transverse. When the arachnoid mem- 
 brane and the pia mater are removed, you observe that its surface 
 is not arranged in convolutions like those of the cerebrum. It is 
 laid out upon a plan adapted to produce a much greater super- 
 ficial extent of grey matter. It consists of a multitude of thin 
 plates, disposed in a series of concentric curves, with the concavity 
 forwards. By a little careful dissection, it is easy to separate 
 some of the plates from each other, and to see that the intervening 
 fissures increase in depth from the centre towards the circum- 
 ference of the cerebellum. The fissure at the circumference itself 
 is the deepest of all, and nearly horizontal, so that it seems to 
 divide the cerebellum into an upper and a lower segment. 
 
 is formed sooner than any of the others ; because it exists in all vertebrated animals, 
 whereas the lateral ventricles are absent in all osseous fishes ; and because the ventricle 
 of the septum lucidum is absent in all fishes, in reptiles, and in birds. 
 
542 DISSECTION OF THE BRAIN. 
 
 The upper surface of the cerebellum slopes on each 
 
 surface s ^ e ' h av * n g a ridge along the middle line, called the 
 
 6 superior vermiform process*' Comparative anatomy 
 proves that this is really the fundamental part of the cerebellum. 
 The sides, called the ' hemispheres? are merely offsets or wings, 
 superadded for special purposes, and increase in size as we ascend 
 in the vertebrate series, till in man they form by far the largest 
 part of the organ. They are separated posteriorly by a perpen- 
 dicular fissure, which receives the ( falx cerebelli.' On the upper 
 surface of the cerebellum are two lobes, which have received 
 names, i.e. the quadrate lobe, situated on its external and anterior 
 aspect, and the posterior lobe, placed along its posterior border. 
 
 On the under surface of the cerebellum, its division 
 Under ' m ^ Q ^ wo hemispheres is clearly perceptible. The deep 
 
 furrow between them is called ' the valley.' The front 
 part of it is occupied by the medulla oblongata. To examine the 
 surface of the valley, the medulla must be raised, and the hemi- 
 spheres separated from each other. Along the middle line of the 
 valley, is the ' inferior vermiform process,' which is the under 
 surface of the fundamental part of the cerebellum. Traced for- 
 wards, this process terminates in the 'nodule-,' traced backwards, 
 it terminates in a small conical projection, called the 'pyramid : ' 
 between these, is a tongue-like body called the ' uvula.' 
 
 Each hemisphere presents on its under surface certain secondary 
 lobes, to which fanciful names have been applied. That portion 
 which immediately overlays the side of the medulla oblongata is 
 called the 'tonsil' (amygdala): at the anterior part of each 
 hemisphere, near the middle line, is a little lobe called the 'floc- 
 culus,' or pneumogastric lobe. 
 
 From either side of the uvula may be traced a thin valve-like 
 fold of white substance, which proceeds in a semicircular direction 
 to the nocculi. These folds form the posterior medullary velum.* 
 To see this satisfactorily, the tonsils should be carefully separated 
 from each other. 
 
 * These were first pointed out by Tarini, and are sometimes called the ' valves of 
 Tarini' (Advers. Anat. prima: Paris, 1750). 
 
PEDUNCLES OF THE CEREBELLUM. 543 
 
 In addition to the amygdala and flocculi already mentioned, 
 other lobes have been described on the under surface of the cere- 
 bellum. Thus, there is the digastric lobe, situated external to 
 the amygdala ; and behind this are successively the slender and 
 the inferior posterior lobes. 
 
 To examine the internal structure of the cerebellum, 
 Appearance 
 of the a longitudinal section should be made through the 
 
 interior. thickest part of one of the hemispheres. There is then 
 seen in the centre a large nucleus of white matter, from which 
 branches radiate into the grey substance in all directions. Each 
 of these branches corresponds to one of the plates of the cere- 
 bellum, and from it other smaller branches proceed and again 
 subdivide. This racemose appearance of the white matter in the 
 substance of the grey has been likened to the branches of a tree 
 deprived of its leaves, and is generally known as the f arbor vitce ; ' 
 it is a beautiful contrivance for bringing an extensive surface 
 of the two kinds of nervous matter into connection with each 
 other. 
 
 In the centre of the white nucleus of each hemi- 
 " s P nere * s an ova ^ s P ace > circumscribed by a zigzag line 
 of grey matter. To this the name ' corpus dentatum 
 or rhomboideum ' has been given. It is displayed both by a 
 vertical and by a horizontal section. 
 
 Peduncles of ^e cere ^ e ^ um i s connected with the cerebro-spinal 
 the cere- axis by three peduncles or crura superior, middle, and 
 belhim. inferior. With the medulla oblongata it is connected 
 by means of the restiform tracts these are called the processus a 
 cerebello ad medullam or its inferior crura ; with the cerebrum, by 
 means of the processus a cerebello ad testes these are called its 
 superior crura. The transverse fibres of the pons constitute the 
 middle crura. 
 
 Respecting the function of the cerebellum, the 
 Function. . 
 
 arguments lurmshed by comparative anatomy render 
 
 probable that it is a co-ordinator of muscular movements e.g. in 
 the action of walking, flying, swimming, &c. 
 
544 SPINAL CORD. 
 
 DISSECTION OF THE SPINAL COED. 
 
 To see the spinal cord covered by its membranes, the arches of 
 the vertebrae must be removed by the saw. The first thing to be 
 noticed is, that the cord does not occupy the whole area of the 
 spinal canal. The dura mater does not adhere to the vertebrae, and 
 does not form their internal periosteum, as in the skull. Between 
 the bones and this membrane, a space intervenes, which is filled 
 by a soft, reddish-looking fat, by watery cellular tissue, and by the 
 ramifications of a plexus of veins. 
 
 The spine is remarkable for the number of large and 
 
 Spmal system f or t. UO us veins which ramify about it, inside and outside 
 of veins. J 
 
 the vertebral canal.* They are 1. The dorsal veins, 
 which form a tortuous plexus outside the arches of the vertebrae. 
 They send off branches, which pass through the ligamenta sub- 
 flava, and end in the plexus inside the vertebral canal. 2. The 
 veins from the bodies of the vertebrce emerge from their posterior 
 surface, and empty themselves into, 3, the anterior longitudinal 
 spinal veins : these, two in number, extend all down the spinal 
 canal, behind the bodies of the vertebrae. 4. The posterior longi- 
 tudinal spinal veins, like the anterior, run along the whole length 
 of the spinal canal. They are situated inside the vertebral arches, 
 and communicate with the anterior longitudinal veins by cross 
 branches at frequent intervals. 5. The proper veins of the spinal 
 cord, which lie within the dura mater. This complicated system 
 of spinal veins discharges itself through the intervertebral fora- 
 mina, in the several regions of the spine, as follow : in the 
 cervical, into the vertebral veins ; in the dorsal, into the inter- 
 costal veins ; in the lumbar, into the lumbar veins. None are 
 provided with valves, hence they are liable to become congested in 
 diseases of the spine. 
 
 * An accurate description and representation of these veins has been given by 
 Breschet, Essai sur les Vemes du Rachis, 4to. ; Trait6 Anatomique snr le Systeme 
 Veineux, fol. avec planches. 
 
MEMBRANES OF THE SPINAL CORD. 545 
 
 Peculiar!- ^ ie mem ^ ranes f the spinal cord, though continuous 
 
 ties of the with those of the brain, differ from them in certain 
 oTthtTcord res P ec ts, and require separate notice. 
 
 The *dura mater' of the cord is a tough fibrous 
 membrane like that of the brain, but does not adhere 
 to the bones, because such adhesion would impede the free move- 
 ment of the vertebrae upon each other. It is attached above to 
 the margin of the foramen magnum, and may be traced down- 
 wards as a canal as far as the first bone of the sacrum, from which 
 it is prolonged as a cord to the coccyx, where it becomes continuous 
 with the periosteum. It forms a complete canal, which loosely 
 surrounds the spinal cord, and sends off prolongations over each 
 of the spinal nerves. These prolongations accompany the nerves 
 only as far as the intervertebral foramina, and are then blended 
 with the periosteum. 
 
 Cut through the nerves which proceed from the spinal cord on 
 each side, and remove the cord with the dura mater entire. Then 
 slit up the dura mater along the middle line, to examine the 
 arachnoid membrane. 
 
 The ' arachnoid membrane ' of the cord is a continu- 
 membrane ^ion from that of the brain, and, like it, consists of a vis- 
 ceral layer which surrounds the cord, and of a parietal, 
 which lines the inner surface of the dura mater. The visceral 
 layer is not in immediate contact with the pia mater underneath, 
 but is separated from it by a transparent watery fluid contained 
 in the meshes of the subarachnoid tissue (p. 548). This cerebro- 
 spinal fluid cannot be demonstrated unless the cord be 
 l ~ examined very soon after death, and before the removal 
 of the brain.* The nerves proceeding from the cord 
 
 * The existence and situation of the cerebro-spinal fluid were first discovered by 
 Haller (Element. Phys. vol. iv. p. 87), and subsequently more minutely investigated 
 by Magendie (Recherches Phys. et Cliniques sur le Liquide Cephalo-rachidien, in 4to. 
 avec atlas: Paris, 1842). This physiologist has shown that if, during life, the arches 
 of the vertebrae are removed in a horse, dog, or other animal, and the dura mater of 
 the cord punctured, there issue jets of a fluid which had previously made the sheath 
 tense. The fluid communicates, through the fourth ventricle, with that in the general 
 ventricular cavity. The collective amount of the fluid varies from 1-to 2 oz. or more. 
 
 X N 
 
546 SPINAL CORD. 
 
 are loosely surrounded by a sheath of the arachnoid ; but this only 
 accompanies them as far as the dura mater, and is then reflected 
 upon that membrane. 
 
 The pia mater of the cord is the protecting membrane 
 which immediately invests it. It is quite different 
 from that of the brain, since it does not form a bed in which the 
 arteries break up, but serves rather to support and strengthen the 
 cord : consequently it is much less vascular, more fibrous in its 
 structure, and more adherent to the substance of the cord. The 
 fibres of which it is composed are rendered very evident by im- 
 mersion for a time in water. It sends down thin folds into the 
 anterior and posterior fissures of the cord, and is prolonged upon 
 the spinal nerves, and forms their investing membrane, or ' neuri- 
 lemma.' 
 
 From the upper part of the second lumbar vertebra, the pia 
 mater is continued down as a slender filament, called the 'jilum 
 terminate? which runs in the middle of the bundle of nerves into 
 which the spinal cord breaks up. It is prolonged to the sacrum, 
 where it becomes continuous with the dura mater of the cord. In 
 its upper part may be traced some nerve matter, continued from 
 the spinal cord, and a small artery and vein. 
 
 The pia mater sends off from each side of the cord, 
 a j on g ft s whole length, a fibrous band, 6 ligamentum 
 denticulatum,' which gives off a series of processes to 
 steady and support the cord. They are triangular, their bases 
 being attached to the cord, and their points to the inside of the 
 dura mater (fig. 130). There are from eighteen to twenty-two of 
 them on each side, and they lie between the anterior and posterior 
 
 It can be made to flow from the brain into the cord, or vice versa. This is proved by 
 experiments on animals, and by that pathological condition of the spine in children 
 termed ' spina bifida.' In the latter instance, coughing and crying make the tumour 
 swell ; showing that fluid is forced into it from the ventricles. Again, if pressure be 
 made on the tumour with one hand, and the fontanelles of the child examined with 
 the other, in proportion as the spinal swelling decreases so is the brain felt to swell 
 up, accompanied by symptoms resulting from pressure on the nervous axis generally. 
 See also some remarks by Dr. Burrows, On Diseases of the Cerebral Circulation, 
 p. 50, 1846. 
 
SPINAL CORD. 
 
 047 
 
 SPINAL CORD. 
 
 Fig. 130. 
 
 Cauda 
 equina. 
 
 * DIAGRAM OF THE LIGAMENTUM 
 DENTICULATUM. 
 
 roots of the spinal nerves. The first process passes between the 
 vertebral artery and the hypoglossal nerve ; the last one is found 
 at the termination of the cord. 
 
 The spinal cord is that part 
 
 of the cerebro-spinal axis con- 
 tained in the vertebral canal. It is the 
 continuation of the medulla oblongata, 
 and extends from the foramen magnum 
 down to the upper border of the second 
 lumbar vertebra, where it terminates in 
 a pointed manner, after having given off 
 
 the great bundle of nerves 
 
 termed 'cauda equina,' for the 
 
 supply of the lower limbs.' 
 The length of the cord is about seven- 
 
 1. Dura mater. 
 
 teen or eighteen inches, and its general 2, 2, 2. Ligamentum denticuiatum. 
 form is cylindrical, slightly flattened in 
 
 front and behind. It is not of uniform dimensions throughout. 
 It presents a slight enlargement in the lower part of the cervical 
 region ; another in the lower part of the dorsal, where the great 
 nerves of the upper and lower limbs are given off. The upper 
 or cervical enlargement reaches from the third cervical to the 
 first dorsal vertebra ; the lower or lumbar is situated opposite to 
 the last dorsal vertebra. 
 
 The cord is divided into two symmetrical halves by 
 a fissure in front and behind (fig. 131). The anterior 
 fissure is the most distinct, and penetrates about one-third of the 
 substance of the cord ; it contains a fold of pia mater full of blood 
 vessels for the supply of the interior. At the bottom of this fissure 
 
 * Although the nerve substance of the cord itself terminates at the second lumbar 
 vertebra, yet the pia mater is continued as a slender filament, called 'filum terminate,' 
 down to the base of the coccyx. The explanation of this is, that, at an early period 
 of foetal life, the length of the cord corresponds with that of the vertebral canal ; but 
 after the third month, the lumbar and sacral vertebrae grow away, so to speak, from 
 the cord, in accordance with the more actiA'e development of the lower limbs. See 
 Tiedemann, Anatomie und Bildungsgeschichte des Gehirns im Foetus des Menschen, 
 &c.; Niiremberg, 1816. 
 
 NN'2 
 
 Fissures. 
 
548 
 
 SPINAL CORD. 
 
 is a transverse layer of white substance, named the anterior com- 
 missure, connecting the two anterior halves of the cord. The 
 posterior fissure is so much less apparent than the anterior, that 
 some anatomists altogether deny its existence ; but it can be 
 demonstrated by careful preparation, and, indeed, penetrates to a 
 greater depth than the anterior, so that it reaches down to the 
 grey matter in the centre of the cord. 
 
 Besides the anterior and posterior fissures, along each half of the 
 cord are two superficial grooves, from which the anterior and 
 posterior roots of the spinal nerves respectively emerge. These 
 are the anterior and posterior lateral grooves. The posterior 
 
 Fig. 131. 
 
 1 . Dura mater. 
 
 2. Arachnoid mem- 
 
 brane. 
 
 3. Ganglion on poste- 
 
 rior root of spinal 
 nerve. 
 
 4. Anterior root of 
 
 spinal nerve. 
 
 5,5. Seat of sub-arach- 
 noid fluid. 
 
 6. Posterior branch of 
 
 spinal nerve. 
 
 7. Anterior branch of 
 
 spinal nerve. 
 
 BIAGEAM OF A TRANSVERSE SECTION THROUGH THE SPINAL CORD 
 AND ITS MEMBRANES. 
 
 leads down to the posterior horn of the grey matter in the interior 
 
 of the cord ; the anterior is less distinct, and does not reach down 
 
 to the anterior horn of grey matter. By these lateral 
 
 ins * grooves each half of the cord is divided into three 
 
 longitudinal columns an anterior, a posterior, and a lateral. 
 
 The anterior are motor columns, the posterior sensitive, the lateral 
 
 probably contain both motor and sensitive filaments. 
 
 A transverse section through the cord (fig. 131) shows 
 that, externally, it is composed of white nerve sub- 
 stance, and that its interior contains grey matter, arranged in the 
 form of two crescents placed one in each half of it, and connected 
 across the centre by a portion called the 'grey commissure. 1 * 
 
 * The grey matter in the interior of the cord of man and animals presents some- 
 what different appearances in its different parts. These have been accurately de- 
 
SPINAL CORD. 549 
 
 The posterior horns of the crescents are long and narrow, and 
 extend to the posterior lateral fissure, where they are connected 
 with the posterior roots of the spinal nerves. The anterior horns 
 are short and thick, and come forwards towards the line of attach- 
 ment of the anterior roots of the nerves, but do not reach the 
 surface. 
 
 Thirty-one pair of nerves arise from the spinal cord 
 SPINAL namely, 8 in the cervical region, 1 2 in the dorsal, 5 
 
 NERVES* 
 
 in the lumbar, 5 in the sacral, and 1 in the coccygeal. 
 Each nerve comes off by two distinct series of roots one from 
 Two roots ^ e fr' 011 *' tae otner from the back of the cord. Sir 
 sensitive Charles Bell first noticed the fact that the anterior roots 
 an motor. cons i s t exclusively of motor filaments, the posterior 
 exclusively of sensitive. All converge and unite in the corre- 
 sponding intervertebral foramen to form a single nerve, composed 
 of both motor and sensitve filaments. 
 
 The posterior or sensitive roots proceed from the posterior 
 lateral groove of the cord, and are thicker and more numerous 
 than the anterior.* Previous to their union with the anterior 
 roots, they are collected together and pass through a ganglion. 
 This ganglion is of an oval form, and lies in the intervertebral 
 foramen, where the roots of the nerves pass through the dura 
 mater.f 
 
 The anterior root arises from the groove between the anterior 
 and lateral columns of the cord, and passes in front of the 
 
 scribed and figured by Rolando, Richerche Anatomiche sulla Struttura del Midollo 
 Spinale, con Figure, art. tratto dal Dizionario Periodico di Medicina, Torino, 1824, 
 8vo. p. 55. 
 
 * The researches of Blandin, Anat. closcript. t. ii., p. 648, 1838, hare led him to 
 establish the following relation between the respective size of the anterior and pos- 
 terior roots of the nerves in the several regions of the spine: 
 
 The posterior roots are to the anterior in the cervical region : : 2 1 
 
 ,, dorsal :: 1 
 
 lumbar and sacral 
 
 This relation quite accords with the greater delicacy of the sense of touch in fhe 
 upper extremity. 
 
 f The ganglia of the two last sacral nerves lie within the dura mater. 
 
550 SPINAL CORD. 
 
 ganglion on the posterior root, which it joins in the inter vertebral 
 foramen. 
 
 The compound nerve formed by the junction of the two roots 
 divides, outside the intervertebral foramen, into an anterior and 
 a posterior branch. See diagram, p. 548. 
 
 Variation in ^ Qe direction and length of the roots of the nerves 
 length of vary in the different regions of the spine, because the 
 the roots. respective parts of the cord from which they arise are 
 not opposite the foramina through which the nerves leave the 
 spinal canal. In the upper part of the cervical region, the origins 
 of the nerves and their point of exit are nearly on the same level : 
 therefore the roots proceed transversely, and are very short. But 
 as we descend from the neck, the obliquity and length of the 
 roots gradually increase, so that the roots of the lower dorsal 
 nerves are at least two vertebras higher than the foramina through 
 which they emerge. Again, since the cord itself terminates at 
 the second lumbar vertebra, the lumbar and sacral nerves must of 
 necessity pass down from it almost perpendicularly through the 
 lower part of the spinal canal. To this bundle of nerves the old 
 Caud e uina ana t m i s ts nave gi ven the name of < cauda equina,' 
 from its resemblance to a horse's tail. 
 
 In brief, then, it appears that the spinal cord consists of two 
 precisely symmetrical halves, separated in front and behind by a 
 deep median fissure ; that the two halves are connected at the 
 bottom of the anterior fissure by an anterior or white commissure 
 at the bottom of the posterior fissure by the posterior or grey 
 commissure; that each half of the cord is divided into three tracts 
 or columns of longitudinal nerve fibres an anterior, a posterior, 
 and a lateral the boundaries between them being the respective 
 lines of origin of the roots of the spinal nerves ; that the interior 
 of the cord contains grey matter disposed in the form of two 
 crescents placed with their convexities towards each other, and 
 connected by a transverse bar of grey matter, which is the posterior 
 commissure. 
 
 Bloodvessels The cor( ^ ^ s supplied with blood by 1, the anterior 
 of the cord, spinal artery, which commences at the medulla ob- 
 
SPINAL CORD. 551 
 
 longata by a branch from the vertebral of each side, and then 
 runs down the cord, receiving, through the intervertebral 
 foramina, numerous branches in its course from the vertebral, 
 ascending cervical, intercostal, and lumbar arteries ; 2, the 
 posterior spinal arteries, which proceed also from the vertebral, 
 intercostal, and lumbar arteries, and ramify very irregularly on 
 the back of the cord. 
 
 On the posterior part of the bodies of the vertebra, the spinal 
 arteries of opposite sides communicate by numerous transverse 
 branches along the entire length of the spine, thus resembling the 
 arrangement of its venous plexuses. 
 
 Functions of The anterior columns consist exclusively of motor 
 the columns fibres which originate from the grey matter of the brain 
 )r ' or that of the spinal cord, and carry the commands of 
 the will and the power of reflex movement to the muscles. 
 
 The posterior columns consist exclusively of sensitive fibres, 
 which carry sensations, not, as was formerly believed, direct to 
 the brain, but to the grey matter of the cord, through which alone, 
 according to the recent experiments of Brown Sequard,* they are 
 transmitted to the brain. The same experimentalist has also 
 proved another unexpected fact that sensations do not run up 
 on the same side, but on the opposite. They cross in the cord ; 
 for instance, if the posterior column on the right side were injured, 
 the left leg and not the right would be deprived of sensation. 
 
 In the interior of the grey matter of the upper part of the spinal 
 cord may be seen a central canal, the remains of the primordial 
 canal of foetal life, which extends through the whole length of the 
 cord. 
 
 MINUTE STRUCTURE These are among the most complicate parts of 
 
 OF THE MEDULLA. the central nervous system. They contain white 
 
 PONS N VAKOL^ D and g 1 ' 6 ^ matter,f intermixed. The white matter 
 
 consists in part of a continuation of the longi- 
 
 * See an able article on Brown Sequard's experiments in the British and Foreign 
 Medico-Chirurgical Review by Mr. Thomas Smith. 
 
 t The grey matter in the medulla oblongata is collected in three situations 1 . 
 In the olives ; 2. In the restiform tracts ; 3. On the floor of the fourth ventricle. 
 
552 
 
 SPINAL CORD. 
 
 tudinal fibres of the cord, in part of a new system of horizontal 
 fibres. We will endeavour to trace the longitudinal fibres first ; 
 then the horizontal. 
 
 Anterior T ^ e anterior columns (8), (fig. 132), having reached 
 
 columns of the lower part of the medulla oblongata, are not con- 
 tinued straight up through it, but diverge from each 
 other, so as to allow a part of the lateral columns (9) to come 
 
 Fig. 132. 
 
 1. Corpus striatum. 
 
 2. Thalamus options. 
 
 3. Crus cerebri. 
 
 4. Locus niger. 
 
 5. Pons Varolii. 
 
 6. Pyramid. 
 
 7. Olive. 
 
 8. Anterior columns. 
 
 9. Lateral columns. 
 
 10. Posterior columns. 
 
 11. Corpora quadrigemina. 
 
 12. Fillet of Reil. 
 
 13. Superior crus of cere- 
 
 bellum. 
 
 14. Cerebellum. 
 
 DIAGRAM OF THE COURSE OF THE FIBRES OF THE CORD. 
 
 forward, and after decussation to form the pyramids (6). In their 
 further progress the fibres of the anterior columns are disposed of 
 thus : a small number of them run up and contribute to form the 
 outer portion of their own pyramid ; all the rest, after embracing 
 the olive, pass up through the deep strata of the pons, and then 
 
SPINAL CORD. 553 
 
 divide into two bundles : one of these, called the fillet of Reil (12), 
 mounts over the superior crus of the cerebellum to the corpora 
 quadrigemina, beneath which it meets with the corresponding 
 fillet of the opposite side ; the other proceeds with the crus cerebri 
 to the cerebrum. 
 
 lateral ^ e ^ atera ^ columns (9), on reaching the medulla ob- 
 
 columns of longata, are disposed of in three ways, as follows Some 
 the cord. Q f ^ s fik res come forward between the diverging anterior 
 columns, decussate in the middle line, and contribute to form the 
 pyramid of the opposite side ; others ascend with the restiform 
 tract into the cerebellum ; a third set ascend along the floor of the 
 fourth ventricle * (concealed by its superficial grey matter), and 
 then along the upper part of the crus cerebri into the cerebrum. 
 
 The posterior columns (10) ascend under the name 
 eotamnTof of tne restiform tracts at the back of the medulla oblon- 
 the spinal gata, diverge from each other, and are, for the most part, 
 
 continued into the cerebellum, forming its inferior crura; 
 but some of their fibres run on along the floor of the fourth ven- 
 tricle (external to the fibres from the lateral columns), then along 
 the upper part of the crura cerebri into the cerebrum. 
 
 The horizontal fibres in the medulla oblongata and 
 JF b r ri g ntal the pons were first accurately described and delineated 
 
 by Stilling.f Some of them form a raphe, and divide 
 the medulla oblongata and pons into symmetrical halves ; others, 
 arising apparently from the raphe, pass outwards in an arched 
 manner through the lateral halves of the medulla ; so that, when 
 seen in a transverse section by transmitted light, they describe a 
 series of curves, with the convexity forwards, throughout the entire 
 thickness of the medulla. Some of these transverse fibres appear 
 on the surface over the pyramid and the olive ; these have received 
 the name of ' ardform fibres' (p. 517). It is difficult to deter- 
 mine the object of this system of transverse fibres, or what parts 
 
 * These fibres constitute what are sometimes called the 'round cords' of the 
 fourth ventricle. 
 
 f Ueber die Medulla Oblongata. Erlangen, 1843. 
 
554 SPINAL CORD. 
 
 they connect. Stilling and Kolliker,* who have deeply studied the 
 subject, are both of opinion that they originate in the restiform. 
 tracts, and thence arch forwards some on the surface, others 
 through the substance of the medulla, and that they eventually 
 join the fibres of the raphe. 
 
 The pons consists of transverse and longitudinal 
 
 Internal struc- r t ' 
 
 ture of pons white fibres, with a considerable quantity of grey 
 matter in its interior. The superficial layer of 
 fibres is obviously transverse, and connects the two wings of the 
 cerebellum. After removing this first layer, we come upon the 
 longitudinal fibres of the pyramids in their course to the crura 
 cerebri (p. 552) : these longitudinal fibres, however, are inter- 
 sected by the deep transverse fibres of the pons, which, like the 
 superficial, are continued into the cerebellum. The third and 
 deepest layer of the pons consists entirely of longitudinal fibres, 
 derived partly from the lateral, partly from the restiform tracts 
 of the medulla. 
 
 These are composed of longitudinal fibres, derived 
 from the pyramids, from part of the lateral and res- 
 tiform columns of the cord, and from the grey matter in the pons 
 Varolii. If one of the crura be divided longitudinally, we find in 
 the middle of it a layer of dark-coloured nervous matter, called 
 f locus niger ; ' it separates the crus into an upper and a lower- 
 stratum of fibres. The lower stratum is tough and coarse, and 
 consists of the continuation of the fibres proceeding from the 
 pyramid and the pons. The upper stratum is much softer and 
 finer in texture, and has received the name of the ' tegmentum : ' 
 it is composed of the fibres proceeding from the lateral and the 
 restiform columns ; also from the superior commissure or crus of 
 the cerebellum. 
 
 Tracing the fibres of the crus cerebri into the cerebral hemi- 
 sphere, we find that they diverge from each other, that its lower 
 fibres ascend chiefly through the corpora striata, its upper fibres 
 through the thalami optici. In passing through these great 
 
 * Mikroskopische Anatoraie, p. 454. 
 
DISSECTION OF THE EYE. 555 
 
 ganglia, the cms receives a very large addition to its fibres : these 
 then branch out widely towards all parts of the hemisphere, in 
 order to reach the cortical substance on the surface. 
 
 From what has been said, it appears that the crura or roots of 
 the cerebellum and the cerebrum contain part of the motor and 
 part of the sensitive tracts of the spinal cord. 
 
 DISSECTION OF THE EYE. 
 
 Since the human eye cannot be obtained sufficiently fresh for 
 anatomical purposes, the student should examine the eyes of 
 animals, of the sheep or pig. The first thing to be done is to 
 remove the conjunctiva! coat, and the loose connective tissue 
 which unites it to the scl erotica. 
 
 The conjunctiva is the mucous membrane which lines 
 Membrana the ocular surface of the eyelids and the front part of 
 the eyeball. It is attached by loose folds to the sclerotic 
 coat, so as not to impede the motions of the globe. The palpebral 
 portion of it is very vascular, and provided with fine papillae which 
 are abundantly supplied with nerves."* It is continued into the 
 Meibomian glands, the puncta lachrymalia, and the ducts of the 
 lachrymal gland. The ocular portion is thinner and has no papillae. 
 It is nearly colourless, except when inflamed ; it then becomes in- 
 tensely vascular and of a bright scarlet colour. An abundant 
 supply of nerves has been bestowed upon the membrane for the 
 purpose of giving it that degree of sensibility necessary to guard 
 the eye. ^ 
 
 The corneal portion is composed chiefly of epithelial cells, ar- 
 ranged in layers. This portion of the conjunctiva cannot be sepa- 
 rated by dissection in recent eyes, but it possesses the same acute 
 sensibility as the rest of the conjunctiva. Changes produced by 
 inflammation of the conjunctiva are often continued over the cornea, 
 
 * These papillae were first pointed out by Eble, Ueber den Ban \md die Krankheiten 
 des Bindehaut des Auges. 
 
556 DISSECTION OF THE EYE. 
 
 and cause the blood vessels on its surface to become injected, and 
 its texture thickened and opaque.* Blood vessels ramify round 
 the margin of the cornea, forming a network arranged in loops. 
 
 The human eye is very nearly spherical, and would be quite so, 
 but that the transparent part in front the cornea forms a seg- 
 ment of a smaller sphere than the rest. Consequently, the antero- 
 posterior diameter of the ball about one inch exceeds the trans- 
 verse by about one line. The convexity of the cornea, however, 
 varies in different persons, and at different periods of life ; this is 
 one cause of the several degrees of near-sight and far-sight. 
 COATS AND ^^ e gl ^ 6 is composed of three coats arranged one 
 HUMOURS OF within the other. The external coat, consisting of the 
 THE EYE. ( sc i ero t{ c an( j cornea,' is fibrous, thick, and strong. The 
 second coat, consisting of the ( choroid, the iris, and ciliary pro- 
 cesses^ is composed of blood vessels, muscular tissue, and pigment 
 cells, and is very dark in colour. The third coat, called the { retina,' 
 consists of the expansion of the optic nerve for the reception of 
 the impression of light. The bulk of the interior is filled with a 
 transparent humour called the 'vitreous.' Imbedded in the front 
 of this, and just behind the pupil, is the crystalline lens for the 
 purpose of concentrating the rays of light. In front of the lens is 
 placed a movable curtain, called the 'iris,' in order to regulate 
 the quantity of light which shall be admitted through the pupil. 
 The space in which the iris is suspended is filled with a fluid 
 termed the ( aqueous ' humour. 
 
 The sclerotic is the tough protecting coat of the eye, 
 
 Sclerotic an d consists of white glistening fibres interlacing in all 
 
 directions. f It covers about |-ths of the globe, the re- 
 
 * The facts of comparative anatomy confirm this view. In the serpent tribe, 
 which annually shed their skin, the front of the cornea comes off with the rest of the 
 external surface of the body. In the eel the surface of the cornea is often drawn off in 
 the process of skinning. In some species of rodents which burrow under the ground 
 like the mole, the eye is covered with hair like other parts. 
 
 f* The sclerotic coat of the eye in fishes is of extraordinary thickness and density, 
 for obvious reasons ; and in birds this coat is further strengthened by a circle of bony 
 plates, fourteen or fifteen in number, arranged in a series round the margin of the 
 cornea. Similar plates are found in some of the reptiles, and particularly in the fossil 
 iethyosauri and plesiosauri. 
 
DISSECTION OF THE EYE. 
 
 557 
 
 Fig. 133. 
 
 maining th being completed by the cornea. The thickest part of 
 the sclerotic coat is at the back of the globe (fig. 134), and thinnest 
 a short distance behind the cornea. 
 The back of the sclerotic is perfor- 
 ated by the optic nerve, which en- 
 ters it a little on the nasal side of 
 the axis of vision. The optic nerve 
 at its entrance into the sclerotic is 
 very much constricted, and instead 
 of passing through a single large 
 aperture in this coat, enters it 
 through a porous network of fibrous 
 tissue called the lamina cribrosa.* 
 Around the optic nerve the sclerotic 
 
 ,, , i -I ,1 ! INSERTION OF THE RECTI MUSCLES WITH 
 
 is perforated by the ciliary arteries, ANTERIOR CILIARY ARTERIES. 
 veins, and nerves, for the supply of 
 
 the choroid coat and the iris. Towards the front, the sclerotic 
 becomes much thinner, and about a quarter of an inch from the 
 cornea it receives the insertion of the recti muscles ; here also 
 it is perforated by the anterior ciliary arteries, which come for- 
 ward along the tendons of these muscles, and form a vascular ring 
 round the margin of the cornea. 
 
 The sclerotic is composed of fibro-cellular tissue arranged in 
 bundles which run, some longitudinally and some transversely. 
 The longitudinal fibres are the most external and abundant. 
 Under the microscope fusiform and stellate cells can be seen inter- 
 spersed among the fibres, between which fine elastic fibres may 
 also be demonstrated. The inner surface of the sclerotic is coated 
 by a thin layer of areolar tissue impregnated with dark pigment 
 cells. It is called ' lamina fusca. 9 At present it is believed that 
 no nerves exist in the sclerotic. 
 
 To examine the cornea, it should be removed with the sclerotic 
 coat. This should be done under water, by making a circular cut 
 
 * In the centre of the lamina cribrosa is an opening larger than the rest, which 
 serves for the transmission of the arteria centralis retinae. It is sometimes called the 
 porus opticus. 
 
$58 
 
 DISSECTION OF THE EYE." 
 
 with scissors about a quarter of an inch from the margin of the 
 cornea. With a little care, it is easy to remove the outer coat of 
 the eye without injuring the dark choroid coat, the ciliary liga- 
 ment, or the iris. In the loose dark-brown cellular tissue between 
 the sclerotic and the choroid are seen the ciliary nerves passing 
 
 Fig. 134. 
 
 
 Hyaloid membrane 
 
 Retina (dotted line) 
 
 Choroid coat (black 
 
 line) .... 
 
 Sclerotic coat . . 
 
 DIAGRAM OF A VERTICAL SECTION OF THE EYE. 
 
 1 . Anterior chamber filled with aqueous humour. 
 
 2. Posterior chamber. 3. Canal of Petit. 
 
 Iris. 
 
 Ciliary pro' esses. 
 
 Canal of Sclilemm 
 
 or Fontana. 
 Ciliary ligament. 
 
 Cornea. 
 
 forwards towards the iris; their white colour makes them very 
 conspicuous on tile dark ground. 
 
 The cornea is the brilliant and transparent coat 
 which occupies about the anterior fifth of the globe. 
 Although apparently delicate, yet it is quite as tough and thick as 
 any part of the sclerotica. It is nearly circular in diameter and 
 is about the J^-th of an inch in thickness. It is firmly connected 
 at its margin to the sclerotic, with the fibres of which it is con- 
 tinuous. The margin of the sclerotic is beveled on the inside ; 
 that of the cornea on the outside; so that the former overlaps the 
 latter (fig. 134). 
 
DISSECTION OF THE EYE. 5.30 
 
 The cornea consists of five layers, which are not all 
 composed of the same kind of tissue. The first layer 
 is the conjunctival. This consists of several strata of epithelial 
 cells, the superficial ones being flattened; the deeper ones, the 
 more numerous, being placed vertically. The second layer is 
 about the yyVoth of an inch thick, and consists of an extremely 
 elastic tissue. It is perfectly structureless, and, when peeled off, 
 has a remarkable tendency to curl up. Boiling, or the action of 
 acids, does not render it opaque like they do the other layers of the 
 cornea.* Very delicate fibres pass obliquely inwards from it, and 
 serve to connect it to the next layer. The third layer (cornea 
 proper} consists of transparent fibrous tissue, upon which the 
 thickness and strength of the cornea mainly depend. The fibres 
 are arranged in layers about sixty in number, between which are 
 branched fusiform cells, communicating freely with each other. 
 The fourth layer is again elastic, and resembles the second layer 
 in structure, except in being somewhat thinner. The fifth layer 
 consists of a layer of epithelial cells, resembling those which 
 line serous membranes. f In its healthy state, the cornea con- 
 tains no blood vessels ; they run back in loops as soon as they 
 reach its circumference. Its nerves, which are numerous, are de- 
 rived from the ciliary nerves, and ramify in the transparent fibrous 
 tissue. 
 
 After the removal of the sclerotic and cornea, we 
 " expose the choroid coat J a white ring, consisting of 
 the ciliary ligament and ciliary muscle, which bounds its anterior 
 parts ; also the iris and ciliary processes, of which the outer cir- 
 cumference is attached to this ring (fig. 134). 
 
 The choroid is the soft and flocculent tunic of the eye, recog- 
 
 * Dr. Jacob calls it ' the elastic cornea/ Med. Chir. Traus., vol. xii. p. 503. Its 
 use, according to Dr. Jacob, is probably to preserve the correct curve of the cornea 
 proper. 
 
 f For a detailed investigation of the structure of the cornea, see Todd and Bowman, 
 Physiological Anatomy. 
 
 J So called, because its outer flocculent surface somewhat resembles the chorion, or 
 external investment of the ovum. 
 
560 DISSECTION OF THE EYE. 
 
 nised by its dark-brown colour and great vascularity. Posteriorly 
 there is a circular aperture in it for the passage of the optic nerve. 
 In front, the choroid is attached to the ciliary ligament, under 
 which it extends forwards, round the circumference of the crystal- 
 line lens, in a series of plaited folds, called the f ciliary pro- 
 cesses? It is connected to the sclerotic by fine cellular tissue- 
 the lamina fusca through which the ciliary vessels and nerves 
 pass forwards. 
 
 Under the microscope the choroid is found to consist of three 
 layers an external, composed of arterial and venous ramifica- 
 tions; a middle, composed of capillaries, and an internal, com- 
 posed of pigment cells. The outer layer consists of the branches 
 of the blood vessels, the arteries being chiefly arranged on its 
 inner, the veins on its outer surface. The veins are arranged 
 with great regularity in drooping branches (vasa vorticosa), like 
 a weeping willow (fig. 135), and converge to four nearly equi- 
 distant trunks, which, after running backwards for a short dis- 
 tance, perforate the sclerotica not far from the entrance of the 
 optic nerve, and empty themselves into the ophthalmic vein. 
 
 The arteries which ramify on the inner side of the veins per- 
 forate the sclerotica near the optic nerve, and then divide and 
 subdivide into a very minute network. Between the vessels are 
 found a number of stellate pigment cells, which communicate 
 with each other. This middle layer, formed by the minute 
 subdivisions of the ciliary arteries, is termed, after the Dutch 
 anatomist Euysch, ' tunica Ruyschiana? It consists of a very 
 delicate capillary network, which extends forwards to the ciliary 
 processes. 
 
 The inner layer is the pigment-matter of the choroid. It is 
 merely adventitious, for,, if the choroid be washed in water or spirit, 
 the colour is entirely removed, leaving the membrane of a greyish 
 tint. In man this pigment is dark brown, but in most animals it 
 is jet black. Under the microscope, it is found to consist of 
 minute hexagonal nucleated cells, filled with pigment granules, 
 which are most numerous towards the margins of the cells. On 
 the choroid it exists only as a single layer, but on the iris and 
 
DISSECTION OF THE EYE. 561 
 
 ciliary processes several layers may be demonstrated.* The use 
 of the pigment is to absorb the rays of light which pass through 
 the retina, and prevent their being reflected. It serves the same 
 purpose as the black paint with which the inside of optical instru- 
 ments is darkened. Albinos, in whom the choroid has little or no 
 pigment, are, consequently, dazzled by daylight, and see better in 
 the dusk.f 
 
 Ciliar bod These structures are best seen when the globe has 
 and pro- been divided by a vertical section into an anterior and 
 cesses. a p OS ^ er i O r half, the vitreous humour being left undis- 
 
 turbed. They should be regarded as a continuation of the choroid, 
 and are arranged as a black circle, about three lines broad, sur- 
 rounding the lens. The posterior boundary of this ring is smooth 
 and flat, and denned by a dentated line. The anterior part presents 
 a number of longitudinal plaits or folds, from sixty to seventy in 
 number, alternately long and short, and arranged in a radiated 
 manner round the circumference of the lens. One of these is 
 seen in the diagram, p. 558. The entire ring is called the ciliary 
 body ; and the folds of it in front, the ciliary processes. The 
 processes are kept in place by being attached to the ciliary liga- 
 ment : they fit into corresponding depressions in the vitreous 
 humour, and their free ends project for a short distance into the 
 posterior chamber. They consist of convolutions of minute arte- 
 ries, and their dark colour arises from the pigment on their 
 surface. Their use is unknown. 
 
 Ciliary The ciliary ligament (fig. 135) is a whitish grey ring, 
 
 ligament. about the Jth of an inch broad, situated just beneath 
 
 * Dalrymple speaks of a very delicate membrane (membrane of Bruch) as lining 
 the inner surface of the choroid, for the purpose of keeping the dark pigment in its 
 place. A similar membrane may be detected on the posterior surface of the iris ; 
 otherwise the pigment there would be apt to be washed away by the aqueous humour. 
 
 f In many of the nocturnal carnivorous quadrupeds, the inner surface of the choroid 
 at the bottom of the eye presents a brilliant colour and metallic lustre. It is called 
 the tapetum. By reflecting the rays of light a second time through the retina, it 
 probably causes the animal to see better in the dusk. It is the cause of the well- 
 known glare of the eyes of cats and other animals ; and the great breadth of the 
 luminous appearance arises from the dilatation of the pupil. 
 
 
 
562 
 
 DISSECTION OF THE EYE. 
 
 the union of the sclerotica and the cornea. It serves as the con- 
 necting medium between several structures namely, the choroid, 
 the iris, the ciliary processes, and the sclerotica. 
 
 Between the sclerotic, the cornea, and the ciliary ligament, is 
 placed a minute circular canal, termed the sinus circularis iridis 
 or canal of Schlemm (fig. 134). It is probably a venous sinus, for 
 it can always be injected from the arteries. 
 
 Fig. 135. 
 
 Sclerotic coat . . . 
 Veins of the choroid . 
 
 Ciliary nerves . . . 
 
 Veins of the choroid . 
 
 - Ciliary ligament. 
 Iris. 
 
 SCLEROTIC COAT REMOVED TO SHOW THE CHOROID, CILIARY LIGAMENT, AND NERVES. 
 
 This muscle consists of unstriped fibres, and is 
 Ciliary attached to the line of junction of the sclerotic and 
 
 cornea; thence its fibres radiate backwards over the 
 ciliary ligament, and are lost in the choroid behind the ciliary 
 processes.* Its action is probably to accommodate the eye to ob- 
 jects at various distances, by rendering the lens more or less 
 convex. 
 
 The iris is a movable curtain suspended in the clear 
 
 fluid, which occupies the space between the cornea and 
 crystalline lens. The iris divides this space into two unequal 
 parts, called the anterior and. posterior chambers (fig. 134); these 
 
 IRIS. 
 
 * Sir Philip Crampton has noticed that this muscle is well developed in birds. 
 them its fibres are of the striped kind, just as the circular fibres of the iris are. 
 
 In 
 
DISSECTION OF THE EYE. 563 
 
 communicate with each other through a circular aperture in the 
 centre, called the pupil.* Its use is to regulate the amount of 
 light which shall be admitted into the eye : for this purpose its 
 inner circumference is capable of dilating and contracting accord- 
 ing to circumstances, while its outer circumference is immovably 
 connected to the ciliary ligament, the choroid, and the cornea. 
 
 The colour of the iris varies in different individuals, and gives 
 the peculiar tint and brilliancy to the eye. The colouring matter 
 or pigment is contained in minute cells (pigment cells} lining the 
 anterior and posterior surfaces of the iris. The posterior surface 
 of the iris, called the uvea^ is covered by a thick layer of black 
 pigment. 
 
 When the iris is laid under water, and viewed with a low mag- 
 nifying power, a number of fine fibres are seen converging from 
 all sides towards the pupil ; many of them unite and form arches. 
 When the pupil is contracted, these fibres are stretched, and vice 
 versa. Whether they co-operate in producing the dilatation of 
 the pupil is uncertain. 
 
 The contractile power of the iris depends upon muscular fibres 
 of the non-striped kind, arranged some in a radiating, others in a 
 circular manner. The radiating (dilatator) converge towards the 
 pupil, where they blend with the circular fibres; the circular 
 (sphincter) are aggregated on the posterior aspect of the pupillary 
 margin, where they form a ring about -j^th of an inch in width. J 
 
 A considerable amount of fibrous tissue is present in the iris, 
 and consists of circular and radiating fibres ; the circular are found 
 at the circumference of the iris, the radiating converge towards 
 the pupil. 
 
 When minutely injected, the iris appears to be composed almost 
 
 * The size and shape of the pupil vary in different animals. In the bullock, sheep, 
 horse, &c., it is oblong ; in carnivorous quadrupeds it is often a mere vertical slit 
 during the day, but dilates into a large circle at night. 
 
 f Strictly speaking, the term uvea was applied by the old anatomists to the choroid 
 and iris collectively, which they very properly considered as one coat, and called the 
 ' XiT&v payoeiSris,' because its dark colour made it like the berry of the grape. 
 
 | The circular fibres of the iris in the bird are of the striped variety, and dis- 
 cernible without difficulty. 
 
 o o 2 
 
564 DISSECTION OF THE EYE. 
 
 entirely of blood vessels ; * so much so that some anatomists con- 
 sider it to be a kind of erectile tissue, and that its power of con 
 tracting and expanding depends upon this property alone. Its blood 
 
 vessels are derived from two sources the posterior 
 vessels d or ^ on ' anc ^ ^he an terior or short ciliary arteries. The 
 
 posterior, 15 to 20 in number, perforate the sclerotica 
 round the optic nerve, and then run on upon the choroid to the 
 iris; the anterior proceed from the tendons of the recti (p. 182), 
 and perforate the sclerotica round the margin of the cornea. It 
 is from the enlargement of these latter vessels that the red zone 
 round the cornea is produced io inflammation of the iris. 
 
 The nerves of the iris, twelve or more in nlim- 
 
 ber, proceed from the lenticular ganglion, and from 
 the nasal branch of the ophthalmic division of the fifth pair 
 .(p. 178). They perforate the back of the sclerotica like the arte- 
 ries, and run along the choroid to the iris. 
 
 Until the seventh or eighth month of foetal life, the 
 pupillaris a P U P^ * s closed by a delicate membrane, termed ( mem-* 
 
 brana pupillaris.' Its vessels are arranged in loops, 
 which converge towards the centre of the pupil. It has been lately 
 discovered that this membrane, which has always been regarded 
 as a distinct structure, is identical with the anterior layer of the 
 capsule of the crystalline lens.f 
 
 To obtain a view r of the retina, the choroid coat must 
 
 be removed while the eye is under water ; this should 
 be done with the forceps and scissors. The optic nerve, having 
 entered the interior of the globe through the sclerotic and the 
 choroid, expands into the delicate nervous tunic called the retina. 
 In passing through the coats of the eye, the nerve becomes sud- 
 denly constricted, and reduced to one-third of its diameter; at 
 this point, too, it projects slightly into the interior of the globe, 
 
 * In well-injected preparations one may see that the chief blood vessels are dis- 
 posed in two circles on the front surface of the iris, one near the outer, and the other 
 near the inner circumference. 
 
 f See a paper by John Quekett in the Transactions of the Microscopic Society of 
 London, vol. iii. p. 9. 
 
DISSECTION OF THE EYE. 565 
 
 forming a little prominence to which the term 'papilla conica* 
 has been applied.* In front the retina ter- 
 minates in a thin serrated border (ora ser- Fi S- 136 - 
 rata\ which ends a short distance behind 
 the posterior margin of the ciliary processes. 
 
 Precisely opposite the pupil there is a 
 bright yellow spot, macula, lutea, in the 
 retina, about -^th of an inch in diameter, 
 fading off gradually at the edges, and having 
 a black spot,fovea centralis, in the centre. ARTEfiIBS OF THE 
 This central spot was believed by its dis- ^f^^. 
 coverer, Soemmering,f to be a perforation ; 
 
 but it is now ascertained to depend upon the absence of the yellow 
 colour in the centre : so that the dark pigment of the choroid 
 becomes conspicuous. These appearances are lost soon after 
 death, and are replaced ^by a minute fold, into which the retina 
 gathers itself, reaching from the centre of the spot to the promi- 
 nence of the optic nerve. The use of this yellow spot is not 
 understood.^ 
 
 Although to the naked eye the retina appears a 
 so ^? semi-transparent membrane, yet, when 
 examined with the microscope, it is found to be most 
 minutely and elaborately organised. It varies in thickness from 
 the -^-th to the -gLth of an inch, and consists of four layers, named 
 from without inwards, the columnar layer or membrana Jacobi, 
 the granular layer, the nervous layer, and the vascular layer. 
 
 The columnar layer or membrana Jacobi is composed of 
 minute cylindrical transparent rods arranged at right angles to the 
 surface of the retina. Their outer extremities are imbedded to a 
 greater or less depth in the dark pigment of the choroid, so that 
 
 * This prominence is remarkable, in that it is insensible to the rays of light. 
 
 f De foramine centrali, &c., retinae humanae; in Comment. Soc. Gotting. t. 13. 
 
 { In birds the retina has throughout the yellowish colour seen only at one part in 
 the human eye. 
 
 After its discoverer, Dr. Jacob of Dublin, who described it in the Philosophical 
 Transactions, 1819. 
 
566 DISSECTION OF THE EYE. 
 
 when viewed from without, the rods have the appearance of mosaic 
 pavement.* Among the rods are intermingled numerous flask- 
 shaped bodies, called cones: their outer extremities taper off 
 towards the choroid, with which they are in contact, their inner 
 broad ends join the fibres of Miiller. The rods are absent in the 
 macula lutea. 
 
 The granular layer consists of two horizontal collections of oval 
 cells, separated by a variable amount of granular material. 
 
 The nervous layer is composed of the terminations of the optic 
 nerve fibres, and of branched nerve cells. The fibres of the optic 
 nerve, consisting only of the axis cylinders, run forwards as a con- 
 tinuous layer, and terminate in the nerve cells. The fibres are 
 absent on the yellow spot.f 
 
 The vascular layer is formed by the ramifications of the ar- 
 teria centralis retinae, which form a close network of blood vessels 
 throughout the nervous substance for its nutrition. After a short 
 maceration in water, the nervous substance can be brushed off 
 with a camel's hair brush, and then, in an injected eye, the net- 
 work formed by the vessels can be distinctly seen. The larger 
 branches, however, are visible without injection ; one of them runs 
 round the free margin of the retina. 
 
 The retina is separated from the vitreous humour by a perfectly 
 transparent membrane, the membrana limitans. At the yellow 
 spot the retina has no rods, and over the fovea centralis it is desti- 
 tute of the granular layer and the nerve fibres. 
 
 The aqueous humour consists of a few drops of alka- 
 c ^ ear wa t er j fluid, which fills up the space between 
 the cornea and crystalline lens. The iris floats freely 
 in it, and divides the space into two chambers of unequal size 
 an anterior and a posterior. The posterior is much the smaller of 
 the two : indeed, the iris is so close to the lens that they are sepa- 
 rated by a mere film of fluid. This accounts for the frequent 
 
 # See Hannover, Recherches Microscop. sur le Systeme nerveux, 1844. 
 
 f* H. Miiller has described a number of radiating fibres, which are connected ex- 
 ternally with the rods and cones, and after passing through the whole thickness of the 
 retina, end in triangular expansions which rest on the membrana limitans. 
 
DISSECTION OF THE EYE. 567 
 
 adhesions which are apt to take place, during inflammation, between 
 the pupil and the capsule of the crystalline. Some anatomists 
 describe the anterior chamber as lined by a serous membrane, 
 which they call the membrane of the aqueous humour. A deli- 
 cate layer of epithelium exists on the posterior surface of the 
 cornea, but nothing like a continuous serous membrane can be 
 demonstrated on the iris or the capsule of the lens. The anterior 
 chamber is remarkable for the rapidity with which it absorbs and 
 secretes, as is proved, in the one case, by the speedy removal of 
 extravasated blood ; in the other, by the rapid re-appearance of the 
 aqueous humour after the extraction of a cataract. 
 
 The vitreous humour is a transparent, gelatinous- 
 
 "Vitreous 
 
 humour and looking substance, which fills up nearly four-fifths of 
 hyaloid ne interior of the globe (p. 558). It consists of a 
 watery fluid contained in the meshes of a cellular struc- 
 ture, called the 'hyaloid membrane,' from its perfect translu- 
 cency : the cells communicate freely with each other ; for, if any 
 part of it be punctured, the humour gradually drains off. The 
 membrane itself is so delicate, that it is difficult to obtain it sepa- 
 rately ; but it may be rendered slightly opaque by strong spirit or 
 diluted acids. It is of somewhat firmer consistence on the surface, 
 so that it answers the purpose of a capsule for the vitreous humour, 
 and is sufficiently strong to keep it in shape after the stronger 
 tunics of the eye have been removed.* 
 
 In the foetus, a branch of the retinal artery runs through the 
 centre of the vitreous humour, and ramifies on the back of the 
 capsule of the lens. It is lodged in a tubular canal in the hyaloid 
 membrane, termed the hyaloid canal ; but this entirely disappears 
 in the adult. 
 
 The vitreous humour presents in front a deep depression, in 
 
 * The cells of the vitreous humour may sometimes be demonstrated by freezing 
 the eye and then dividing it. The figure and size of the cells are shown by the por- 
 tions of ice which they contain. Again, by macerating the eye in chromic acid, it is 
 found that the vitreous humour is intersected by 180 delicate partitions, disposed 
 like those in the pulp of an orange with this difference, however, that the partitions 
 do not quite reach the centre, but leave a cylindrical space in the axis of the humour. 
 Up this space the central artery runs in the fcetus. 
 
568 DISSECTION OF THE EYE. 
 
 Zone of which the crystalline lens is imbedded ; around this 
 Zinn. depression is the c zone of Zinn.'* This zone is best 
 
 .exposed by removing the ciliary body. It then appears like a 
 dark disk, and extends from the front margin of the retina nearly 
 to the capsule of the lens : its surface is marked by prominent 
 ridges which correspond with the intervals between the ciliary 
 processes (fig. 136). It is supposed to form the suspensory liga- 
 ment for maintaining the lens in its proper position. 
 
 If the transparent membrane between the zone of 
 p*^* c Zinn and the margin of the lens be carefully punctured, 
 and the point of a small blow-pipe gently introduced, 
 we may succeed in inflating a canal which encircles the lens, and, 
 when inflated, resembles a circle of small glass beads : this is the 
 canal of Petit, or 'canal godronne' (fig. 136, p. 565). How this 
 canal is formed, whether by the separation of the hyaloid mem- 
 brane into two layers or not, and what is its use, are questions not 
 satisfactorily determined. 
 
 The crystalline lens (fig. 134) is a perfectly trans- 
 P aren t solid body, situated immediately behind the 
 pupil, and partly imbedded in the vitreous humour. 
 It is convex on both surfaces, but more so behind. Its shape and 
 consistence vary at different periods of life. In early life it is 
 nearly spherical and soft, but it becomes more flattened, firmer, 
 and amber-coloured with advancing age. In the adult, its trans- 
 verse diameter is about three-eighths of an inch; its antero- 
 posterior, one-fifth of an inch. 
 
 The lens is surrounded by a capsule equally transparent as it- 
 self. The capsule is composed of tissue exactly similar to the elastic 
 layer of the cornea. It is four times thicker in front than behind, 
 as might be expected, for the sake of more effective support. No 
 vascular connection whatever exists between the lens and itscapsule.j 
 
 * Zinn was Professor of Anatomy at Gottingen about the middle of the eighteenth 
 century, and author of ' Descriptio Anat. Oculi Humani.' 
 
 f The vessels of the capsule of the lens are derived from the arteria centralis retinae, 
 and, in mammalia, can only be injected in the foetal state. In the reptilia, however, 
 the posterior layer of the capsule is permanently vascular. According to Quekett, 
 
-DISSECTION OF THE EAR. 569 
 
 The lens protrudes directly the capsule is sufficiently opened. The 
 lens is nourished by means of an extremely delicate layer of nucle- 
 ated cells on its surface, which absorb nourishment from the cap- 
 sule. Some anatomists speak of a layer of fluid (liquor Morgagni) 
 as existing between the lens and its capsule ; but no such fluid can 
 be detected during life, and if there be any after death, it is, in 
 all probability, imbibed by the capsule from the aqueous humour. 
 The minute structure of the lens is very remarkable, 
 structure ^ * s g e l a ^ nous i n consistence outside, but grows gradu- 
 ally denser towards the centre. After immersion in 
 nitric acid, alcohol, or boiling water, it becomes hard and opaque. 
 It may then be seen that it is divided into three equal parts, by 
 three lines which radiate from the centre to within one-third of 
 the circumference. Each of these portions is composed of hun- 
 dreds of concentric layers, arranged one within the other, like the 
 coats of an onion. If any single layer be examined with the 
 microscope, we find that it is made up of fibres about - 1 O th of an 
 inch in thickness, and connected together by finely serrated edges. 
 This beautiful dovetailing of the fibres of the lens was first pointed 
 out by Sir David Brewster ; and, to see it in perfection, one ought 
 to take the lens of the common cod-fish. 
 
 The use of the lens is to bring the rays of light to a focus upon 
 the retina. 
 
 DISSECTION OF THE ORGAN OF HEARING. 
 
 The parts constituting the organ of hearing should be examined 
 in the following order:!. The outer cartilage or pinna; 2. The 
 meatus auditorius externus ; which leads to, 3. The tympanum or 
 middle ear ; and, 4. The labyrinth or internal ear, comprising the 
 vestibule, cochlea, and semicircular canals. 
 
 the membrana pupillaris of authors is nothing more than the anterior layer of the 
 capsule. In taking the eye to pieces, it is quite a matter of accident whether the 
 membrane adhere to the iris, or remain in its proper place in front of the lens. See 
 Quekett's paper in the ' Transactions of the Microscopic Society of London,' vol. iii. 
 
570 DISSECTION OF THE EAR. 
 
 The pinna is irregularly oval, and has on its external 
 aspect numerous eminences and hollows, which have 
 received the following names : The outer folded border is called 
 the helix ; the ridge within it, the anti-helix ; between these is a 
 curved groove called the fossa of the helix. The anti-helix bifur- 
 cates towards the front, and bounds the fossa of the anti-helix. 
 The conical eminence in front of the meatus is termed the tragus, 
 on which hair generally grows. Behind the tragus, and separated 
 from it by a deep notch, is the anti-tragus. The lobule is the 
 soft pendulous part, and consists of fat and fibrous tissue. The 
 deep hollow which collects the sonorous vibrations, and directs 
 them into the external meatus, is termed the concha. The pinna' is 
 formed of yellow fibro -cartilage, which is attached by an anterior 
 ligament to the root of the zygoma, and by a posterior to the 
 mastoid process. 
 
 The muscles which move the cartilage of the ear as 
 
 Muscles of w hole, have been described (p. 2). Other small 
 the pinna. - 
 
 muscles extend from one part of the cartilage to 
 
 another; but they are so indistinct, that, unless the subject be 
 very muscular, it is difficult to make them out. The following 
 six are usually described four on the front of the pinna, and two 
 behind it : 
 
 a. The musculus major helicis runs vertically along the front 
 margin of the pinna. 
 
 b. The musculus minor helicis lies over that part of the helix 
 which comes up from the bottom of the concha. 
 
 c. The musculus tragicus lies vertically over the outer surface 
 of the tragus. 
 
 d. The musculus anti-iragicus proceeds transversely from the 
 anti-tragus to the lower part of the anti-helix. 
 
 e. The musculus transversus is on the back of the pinna ; it 
 passes from the back of the concha to the helix. 
 
 /. The musculus obliquus extends vertically from the cranial 
 aspect of the concha to the convexity below it. 
 
 The arteries of the pinna are derived from the posterior auricu- 
 lar, and from the auricular branches of the temporal and occipital. 
 
DISSECTION OF THE EAR. 571 
 
 The nerves are furnished by the auriculo-parotidean branch of the 
 cervical plexus, the temporo- auricular branch of the inferior max- 
 illary, the posterior auricular branch of the facial, and Arnold's 
 nerve from the pneumogastric. 
 
 This passage leads down to the membrana tvmpani. 
 
 Meatus . . 
 
 auditorius or drum of the ear. It is about an inch and a quarter 
 extemus. * n i en gth ; its external opening is broadest in its verti- 
 cal direction ; its termination is broadest in its transverse. The 
 canal inclines at first upwards and forwards, and then curves a 
 little downwards.* 
 
 It is not throughout of the same calibre, the narrowest part 
 being about the middle ; hence the difficulty of extracting foreign 
 bodies which have passed to the bottom of the canal. It is formed 
 partly by a tubular continuation of the concha, partly by an 
 osseous canal in the temporal bone. The cartilaginous portion is 
 about half an inch long, and the osseous portion three-fourths of 
 an inch. The skin and the cuticle are continued down the passage, 
 and becoming gradually thinner, form a cul-de-sac over the mem- 
 brana tympani. The outer portion is furnished with hairs and 
 ceruminous glands, of which the peculiar bitter secretion is for 
 the purpose of keeping the passage moist, and preventing insects 
 from lodging in it. Its arteries are derived from the posterior 
 auricular, internal maxillary, and temporal; its nerve, from the 
 temporo- auricular. 
 
 The tympanum, or middle ear, is an irregular cavity 
 im< in the petrous part of the temporal bone, and lined by 
 mucous membrane. It is filled with air, which is freely admitted 
 through the Eustachian tube ; so that the atmospheric pressure is 
 equal on both sides of the membrana tympani. It contains a chain 
 of small bones, of which the use is to communicate the vibrations 
 of the membrana tympani to the internal parts of the ear. For 
 this purpose one end of the chain is attached to the membrana 
 tympani, the other to the fenestra ovalis. The antero-posterior 
 
 * To obtain a correct knowledge of the length and dimensions of the meatus, 
 sections should be made through it in different directions, or a cast of it taken in 
 common plaster. 
 
572 DISSECTION OF THE EAE. 
 
 diameter of the tympanum is rather less than half an inch, its 
 vertical and transverse diameter about a quarter of an inch. The 
 cavity is bounded by a roof, a floor, an external, an internal, an 
 anterior, and a posterior wall. Its roof and floor are formed by 
 thin plates of bone. Its external wall is formed by the membrana 
 tympani, and partly by bone ; the latter is pierced by the fissura 
 Grlasseri, and the canal for the exit of the chorda tympani nerve. 
 The internal wall presents the following objects, beginning from 
 above : Bridge indicating the line of the aqueductus Fallopii ; the 
 ( fenestra ovalis? which leads into the vestibule of the internal ear, 
 but is closed in the recent state by a membrane, to which is 
 attached the base of the stapes. Below the fenestra ovalis is a bony 
 prominence, the ( promontory ;' it is occasioned by the first turn 
 of the cochlea, and is marked by grooves, in which lie the 
 branches of the tympanic plexus of nerves. Still lower is the 
 6 fenestra rotunda ; ' it leads into the scala tympani of the cochlea, 
 but is closed in the recent state by membrane. Immediately 
 behind the fenestra ovalis, is a small conical eminence, named the 
 f pyramid -^ in the summit of which is a minute aperture, from 
 which the tendon of the stapedius emerges. 
 
 The posterior wall presents a large opening which leads into the 
 mastoid cells, and conveys air into them from the tympanum. 
 
 The anterior wall leads into the ' Eustachian tube, and the 
 6 canal for the tensor tympani,' which are separated from each 
 other by a bony septum, the ( processes cochleariformis.' Lastly, 
 a nerve called the chorda tympani (a branch of the portio dura) 
 runs across it. 
 
 The membrana tympani completely closes the bottom 
 ^ ^ e meatus auditorius. It is nearly circular, and its 
 circumference is set in a bony groove, so that it is 
 stretched somewhat like the parchment of a drum on the outer 
 wall of the tympanum. Its plane is not vertical, but slants from 
 above downwards, forming, with the lower part of the meatus, an 
 angle of 45 : it is slightly conical, the apex being directed inwards 
 towards the tympanum, and firmly united to the handle of the 
 small bone called the ' malleus.' The structure of the membrane 
 
DISSECTION OF THE EAK. 573 
 
 is essentially fibrous ; some of the fibres radiate from the centre, 
 others are circular. Its inner surface is lined by mucous mem- 
 brane ; its outer surface is covered by an extremely thin layer of 
 the true skin. This accounts for the great sensibility of the 
 membrane, and its vascularity when inflamed. 
 
 For a complete account of the JEustachian tube see 
 Eustachian p< 159> Ifc procee( is from the anterior part of the tym- 
 panum downwards and forwards to the pharynx. 
 
 The four small bones in the tympanum are named, 
 Tympanic a ft,er their fancied resemblance to certain implements, 
 the malleus, incus, os orbiculare, and stapes. They 
 are articulated to each other by perfect joints, and are so placed 
 that the chain somewhat resembles the letter Z. Their use is to 
 transmit the vibrations of the membrana tympani to the membrane 
 of the fenestra ovalis, and, through it, to the fluid contained in the 
 internal ear. But they have another use, which would be incom- 
 patible with a single bone namely, to permit the tightening and 
 relaxation of the membrana tympani, and thus adapt it either to 
 resist the impulse of a very loud sound, or to favour a more gentle 
 one. 
 
 The handle of the malleus is nearly vertical, and attached along 
 its whole length to the upper half of the membrana tympani. 
 The long process (processus gracilis) projects at right angles from 
 the body of the bone, runs into the Grlasserian fissure, and receives 
 the insertion of the laxator tympani. The short process receives 
 the insertion of the tensor tympani. 
 
 The incus, or anvil bone, is shaped like a bicuspid molar tooth 
 with unequal fangs. Its broad part articulates with the malleus ; 
 its long process articulates with the stapes, or stirrup bone, through 
 the os orbiculare ; its short process is directed backwards, and its 
 point is fixed in a small hollow at the commencement of the 
 mastoid cells. 
 
 The stapes is horizontal, and its base is attached to the membrane 
 covering the fenestra ovalis. The stapedius muscle is inserted 
 into its neck. 
 
 These muscles, by moving the tympanic bones, tighten or 
 
574 DISSECTION OF THE EAK. 
 
 MUSCLES OF re ^ a ' x the membrane of the tympanum. The f tensor 
 THE TYMPA- tympani ' runs in the canal above and parallel to the 
 Eustachian tube, from the cartilaginous part of which 
 it arises. It passes backwards, and terminates in a round tendon, 
 which enters the fore part of the tympanum through a special 
 bony canal, and is inserted into the root of the handle of the 
 malleus. Its nerve comes from the otic ganglion. Its action is 
 to draw the membrana tympani inwards, and thus render it tense. 
 The * laxator tympani ' arises from the spine of the sphenoid, and 
 is inserted into the long process of the malleus. It is supplied by 
 a branch from the facial nerve. Its action is to relax the mem- 
 brana tympani. The 'stapedius' arises from a tube in the 
 pyramid,* and its tendon is inserted into the neck of the stapes. 
 Its nerve is derived from the facial. Its precise use is not 
 thoroughly understood. 
 
 A branch of the portic dura (chorda tympani) enters 
 ^ e tympanum through a foramen at the base of the 
 pyramid ; it then crosses the tympanum between the 
 handle of the malleus and the long process of the incus (see p. 1 95), 
 and leaves the tympanum through a canal (canal of Huguier), 
 which runs close to the Glasserian fissure. 
 
 The tympanum is supplied with blood, 1, by the tympanic 
 branch of the internal maxillary, which runs in through the fissura 
 Grlasseri ; 2, by the stylo-mastoid branch of the posterior auricular ; 
 
 3, by small branches which enter with the Eustachian tube; 
 
 4, by branches from the internal carotid artery ; and, 5, by the 
 petrosal branch of the arteria meningea media. 
 
 This, in consequence of its complexity, is appropri- 
 INTERNAL a tely termed 'the labyrinth.' It consists of cavities 
 excavated in the most compact part of the temporal 
 bone. These cavities are divided into three a middle one, 
 called ' the vestibule,' as being a centre in which all communicate 
 with each other ; an anterior, named, from its resemblance to a 
 
 * There is a little sheath, lined by synovial membrane to facilitate the play of the 
 tendon in the pyramid. 
 
DISSECTION OP THE EAR. 575 
 
 snail's shell, the cochlea ; and a posterior, consisting of three semi- 
 circular canals. These cavities are filled with a clear fluid, called 
 the endo-lymph, and contain a membranous expansion (the 
 membranous labyrinth), upon which the filaments of the auditory 
 nerve are expanded. 
 
 The vestibule, or central chamber, communicates in 
 front with the cochlea, through the scala cochleae; 
 behind, with the semicircular canals; on the outside with the 
 tympanum, through the fenestra ovalis ; on the inside is a shallow 
 depression, the fovea hemi-spherica, through which are transmitted 
 the branches of the auditory nerve. In the roof is an oval depres- 
 sion the fovea hemi-elliptica. In some subjects there is the 
 opening of a small canal, termed the c aqueductus vestibuliS It 
 leads to the posterior surface of the temporal bone, and transmits 
 a small vein. 
 
 The semicircular canals, three in number, are situ- 
 
 ated above and rather beMnd the vestibule. Each 
 canal is about the -^th of an inch in diameter, and 
 forms |rds of a circle. They open at each extremity into the 
 vestibule : therefore, there should be six apertures for them ; but 
 there are only five, since one of the apertures is common to the 
 extremity of two canals. The canals are not precisely of equal 
 diameter throughout ; each presents at one end a dilatation 
 termed the ' ampulla.' This dilatation corresponds to a similar 
 dilatation of the membranous sac upon which the auditory nerve 
 expands. Each canal differs in its direction : they are named, 
 accordingly, superior, posterior, and external. The superior s. c. 
 is also the most anterior of the three : its direction is vertical, 
 and runs across the petrous bone : the ampulla is at the outer ex- 
 tremity. Its non-ampullated extremity opens by a common orifice 
 with the posterior s. c. The posterior s. c. is also vertical, runs 
 parallel to the posterior surface of the petrous bone, and, con- 
 sequently, at right angles to the preceding : the ampulla is at the 
 lower end. The external s. c. is horizontal in position with the 
 convexity of the arch directed backwards : the ampulla is at the 
 outer end. 
 
576 DISSECTION OF THE EAR. 
 
 The cochlea is the most anterior part of the internal 
 Cochlea. .. , , , , .,, , ,, 
 
 ear : it very closely resembles a common snails shell, 
 
 and is placed so that the base of the shell corresponds to the 
 bottom of the meatus auditorius internus, while the apex is 
 directed forwards and outwards. It consists of the spiral convolu- 
 tions of two parallel and gradually tapering tubes, which wind 
 round a central pillar, called the c modiolus.'' The partition by 
 which the tubes are separated is termed the ( lamina spiralis." 1 
 In the dry bones this partition is only partial; but, in the recent 
 state, it is completed by a membrane. At the apex of the cochlea 
 (helicotrema) the partition is altogether absent, so that here the 
 tubes communicate with each other. These tubes are called the 
 scales of the cochlea, and are filled with fluid. The upper one 
 opens into the vestibule, and is therefore called the vestibular 
 scale ; the lower one leads to the membrane which closes the fora- 
 men rotundum of the tympanum, and is termed the tympanic 
 scale. If unwound, they would be about 1^ inch long. Each 
 makes two turns and a half round the central pillar, from left to 
 right in the right ear, and vice versa in the left. 
 
 The central pillar of the cochlea is called the ' modiolus.' It is 
 of considerable thickness at the base, but gradually tapers towards 
 the apex. Its interior is traversed by numerous canals, for the 
 purpose of transmitting the filaments of the auditory nerve. One 
 of these canals, larger than the others, runs down the centre of 
 the modiolus nearly to the apex, and transmits a small artery, 
 the c arteria centralis modioli.' 
 
 The lamina spiralis the partition between the two tubes or 
 scales of the cochlea is made up, on the inner half, of bone, on 
 the outer half, of membrane. The bony part has a number of 
 minute canals in it, which come off at right angles from the modi- 
 olus. They are for the lodgment of the filaments of the auditory 
 nerve in their course to the membranous part, which is the most 
 important element of the cochlea, since it receives the undulations 
 of the fluid in the interior.* 
 
 * There is an extremely delicate little muscle, termed the ' cochlearis,' for the 
 purpose of tightening or relaxing, according to circumstances, the membranous part 
 
DISSECTION OF THE EAR. 577 
 
 The osseous labyrinth is lined throughout by a delicate fibro- 
 serous membrane, which secretes the fluid called the < peri-lymph,' 
 or ' liquor Cotunnii.' 
 
 If the bony labyrinth just now described be properly 
 understood, there is no difficulty in comprehending the 
 membranous labyrinth in its interior a structure in- 
 tended to support the ultimate ramifications of the auditory nerve, 
 and to expose them to the undulations of the fluid in the internal 
 ear. 
 
 The membranous labyrinth is a sac, situated partly in the 
 vestibule, partly in the semicircular canals that situated in the 
 vestibule is termed the vestibular portion ; that in the bony canals, 
 the membranous semicircular canals. The semicircular canals 
 present the same dilatations or ampullae at one end, and just at 
 this part they nearly fill their bony cases ; but in the rest of their 
 extent the diameter of the membranous canal is not more than 
 one-third that of the bony one. 
 
 The sac in the vestibule is constricted, so as to appear like two 
 sacs of unequal size. The larger of the two, generally called the 
 utricle., is lodged in the fovea hemi-elliptica, and communicates 
 with the semicircular canals. The smaller, called the saccule, lies 
 in the fovea hemi-spherica, and communicates with the vestibular 
 scale of the cochlea. Both sacs are filled with the endo-lymph, 
 besides which, each contains a minute quantity of calcareous 
 matter, called by Breschet the otoliths. These masses of cretace- 
 ous substance seem to be suspended in the fluid contained in the 
 sacs by the intermedium of a number of nerve filaments proceed- 
 ing from the auditory nerve.* 
 
 The membranous labyrinth is protected, inside and out, by fluid. 
 There is the proper fluid in the interior, termed the c endo-lymph,' 
 
 of the lamina spiralis. It is placed along the outer circumference of the membrane, 
 and, in fact, forms an integral part of it. Its fibres are of the non-striped kind, like, 
 the ciliary muscle of the eye. See Todd and Bowman, Phys. Anat. Part iii. p. 79. 
 
 * From the universal presence of these chalky bodies in the labyrinth of all 
 mammalia, and from their much greater hardness and size in aquatic animals, there 
 s little reason to doubt that they perform some office of great importance in the 
 physiology of hearing. 
 
 PP 
 
578 DISSECTION OF THE EAR. 
 
 and the thin layer of fluid, the ' peri-lymph,' between it and the 
 bone. 
 
 D' t 'b t' The au( litory nerve, or portio mollis of the seventh 
 
 of the audi- pair, passes down the meatus auditorius internus, and, 
 tory nerve. a j. ^ Bottom of it, divides into an anterior and a pos- 
 terior branch: a branch for the cochlea, and a branch for the 
 vestibule. These nerves then break up into numerous fasciculi, 
 which pass through the foramina at the bottom of the meatus into 
 the osseous labyrinth. Here the filaments are grouped into six 
 bundles, corresponding to the parts which they supply namely, 
 two for the vestibular sac, one for each of the ampullae of the 
 semicircular canals, and one for the cochlea. 
 
 The cochlear nerve divides into filaments, which run through 
 the canals of the modiolus, and then along those of the lamina 
 spiralis, in order to terminate upon the membranous part of this 
 lamina. The precise manner in which the filaments terminate is 
 still dubious : according to Breschet,* they communicate and form 
 a series of minute arches. 
 
 Kespecting the other nerves, little more need be said than that 
 their ultimate ramifications are lost upon the vestibular sac, and 
 upon the ampullae of the semicircular canals : some of them, how- 
 ever, pass into the sac, and come into contact with the otoconies, 
 or ear-dust, in its interior. 
 
 -o, , , The internal auditory artery a branch of the basilar 
 Blood vessels J J 
 
 of the laby- runs with the auditory nerve to the bottom of the 
 meatus, and divides into branches corresponding with 
 the divisions of the nerve. Its ultimate ramifications terminate, 
 in the form of a fine network, on the membranous labyrinth, and 
 on the spiral lamina of the cochlea. The auditory vein pours its 
 blood into the superior petrosal sinus. 
 
 * Recherches Anat. et Phys. sur 1'Organe de 1'Oui'e, &c, (Mem. de 1'Acad. de 
 Med. t. v. fasc. iii. 1836.) 
 
DISSECTION OF THE MAMMARY GLAND. 579 
 
 DISSECTION OF THE MAMMARY GLAND. 
 
 The form, size, position, and other external characters of the 
 mammary gland, are sufficiently obvious. The longest diameter 
 of the gland is in a direction upwards and outwards towards the 
 axilla ; its thickest part is at the centre ; and the fullness and 
 roundness of the gland depend upon the quantity of fat which is 
 situated about it and between its lobes. Its deep surface is 
 flattened in adaptation to the pectoral muscle, to which it is 
 loosely connected by an abundance of areolar tissue. 
 
 It is inclosed by a fascia which not only supports it as a whole, 
 but penetrates into its interior, so as to form a framework for its 
 several lobes ; hence it is that, in cases of mammary abscess, the 
 matter is apt to be circumscribed, not diffused. 
 
 The nipple (mammilla] projects a little below the centre; it is 
 surrounded by a coloured circle termed the ' areola : ' this circle 
 is of a rose-pink colour in virgins, but, in those who have borne 
 children, of a dark brown. It begins to enlarge and grow darker 
 about the second or third month of pregnancy, and these changes 
 continue till parturition. The areola is also abundantly provided 
 with papillae, and with subcutaneous sebaceous glands, for the 
 purpose of lubricating the surface during lactation. 
 
 The gland itself consists of distinct lobes held together 
 by firm connective tissue, and provided with separate 
 lactiferous ducts. Each lobe divides and subdivides into lobules, 
 and the duct branches out accordingly.* Traced to their origin, 
 we find that the ducts commence in clusters of minute cells, and 
 that the blood vessels ramify upon these cells in rich profusion; 
 altogether, then, a single lobe might be compared to a bunch of 
 grapes, of which the stalk represents the main duct. The main 
 ducts (galaclophorous ducts) from the several lobes, from fifteen 
 
 * It is observed, in some cases, that one or more lobules run off to a considerable 
 distance from the main body of the gland, and lie imbedded in the subcutaneous tissue. 
 One should remember this when it is necessary to remove the entire gland. 
 
 p p 2 
 
580 DISSECTION OF THE TESTIS. 
 
 to twenty in number, converge towards the nipple, and, just 
 before they reach ? it, become dilated into small sacs or reservoirs 
 two or three lines wide ; after this they run up to the apex of the 
 nipple, and terminate in separate orifices. 
 
 The arteries of the gland are derived from the long thoracic 
 and internal mammary : the nerves come from the antei' or and 
 lateral cutaneous branches of the intercostal nerves. 
 
 DISSECTION OF THE SCEOTUM AND TESTIS. 
 
 The scrotum is composed of six tunics: 1. The 
 skin; 2 ' The tunica dartos; 3. A layer of cellular 
 tissue; 4. The spermatic fascia derived from the ex- 
 ternal abdominal ring ; 5. The cremaster, or suspensory muscle ; 
 6. The infundibuliform fascia derived from the internal ring. 
 
 Each of these coverings cannot be demonstrated under ordinary 
 circumstances, because they are so blended together ; but they 
 can be shown in the case of old and large hernise when in a state 
 of hypertrophy. 
 
 The dartos is a thin layer consisting of muscular 
 
 fibres of the non-striped kind, like those of the bladder 
 
 and intestines. Its use is to corrugate the loose and extensible 
 
 skin of the scrotum, and in a measure to support and brace the 
 
 testicle. 
 
 La er of Beneath the dartos is a large quantity of loose eel- 
 
 cellular lular tissue, remarkable for the total absence of fat. 
 tissue. Together with the dartos, it forms a vertical partition 
 
 between the testicles, termed ( septum scroll? It is not a complete 
 partition, since air or fluid will pass from one side to the other. 
 The great abundance and looseness of this tissue explains the 
 enormous swelling of the scrotum in cases of anasarca, and in 
 cases where the urine is effused into it in consequence of rupture or 
 ulceration of the urethra. 
 
 The spermatic fascia, cremaster muscle, and infundibuliform 
 fascia have been described (pp. 318, 321). 
 
DISSECTION OF THE TESTIS. 
 
 581 
 
 TESTIS. 
 
 The testicle is a gland of an oval shape, with flattened 
 sides, suspended obliquely, so that the upper end points 
 forwards and outwards, the lower end in the reverse direction. 
 The left is generally a little the lower of the two. The ordinary 
 weight of each gland is about six drachms ; but few organs present 
 greater variations in size and weight, even in men of the same 
 
 Fig. 137. 
 
 1. Mediastinum testis contain- 
 
 ing the rete testis. 
 
 2, 2. Trabeculi. 
 
 3. One of the lobules. 
 
 4, 4. Vas recta. 
 
 5. Coni vasculosi forming the 
 
 ' globus major ' of the epi- 
 didymis. 
 
 6. Globus minor, or lower end 
 
 of epididymis. 
 
 7. Vas deferens. 
 
 DIAGRAM OF THE TESTICLE. 
 
 Epididymis. 
 
 age ; generally speaking, the left is the larger. Along the pos- 
 terior part of the gland is placed a long narrow body, 
 termed the s epididymis : ' this is not a part of the 
 testicle, but an appendage to it, formed by the convolutions of its 
 long excretory duct. Its upper larger end is called the ( globus 
 major,' and is connected to the testicle by the efferent ducts ; the 
 lower end, 'globus minor J is only connected to the testicle by 
 fibrous tissue. 
 
 Pro erco- ^ e cover i n g s of the testicle, are 1, a serous mem- 
 verings of bran e, called the ( tunica vaginalis,' to facilitate its 
 testic e. movements ; 2, a strong fibrous membrane, called the 
 ( tunica albuginea,' to support and form a case for the glandular 
 structure within ; 3, a delicate stratum of minute blood vessels, 
 
582 DISSECTION OP THE TESTIS. 
 
 which some anatomists have described as a distinct coat, under 
 the name of tunica vasculosa. 
 
 The tunica vaginalis is a serous sac, one part of 
 which (tunica vaginalis propria) adheres closely to the 
 testicle; the other (tunica vaginalis reflexa) is reflected 
 loosely around it. If the sac be laid open, you see that it com- 
 pletely covers the testicle, except behind, where the vessels and 
 duct are placed (fig. 138); and that it also covers part of the 
 outer side of the epididymis. The interior of the sac is smooth 
 and polished, like all other serous membranes, and lubricated by 
 a little fluid. An excess of this fluid gives rise to the disease 
 termed f hydrocele.' 
 
 The tunica vaginalis was originally derived from the perito- 
 neum. In some subjects it still communicates with that cavity 
 by a narrow neck, and is therefore liable to become the sac of a 
 hernia (see diagram, p. 324). Such hernise are termed congenital 
 a bad name, since they do not, as a matter of course, take place 
 at birth, but often in adult age. Sometimes the communication 
 continues through a very contracted canal, open to the passage of 
 fluid only ; or the communication may be only partially obliterated, 
 and then one or more isolated serous sacs are left along the cord. 
 Such an one, when distended by fluid, gives rise to hydrocele of 
 the cord. 
 
 This tunic is a dense, inelastic membrane, composed 
 altmlnea ^ fi^ rous tissue, interlacing in every direction, analo- 
 gous to the sclerotic coat of the eye. It completely 
 invests the testicle, but not the epididymis. At the posterior part 
 of the gland it penetrates into its substance for a short distance, 
 and forms an incomplete vertical septum, termed, after the anato- 
 mist who first described it, ' corpus Bighmori? and subsequently, 
 by Sir A. Cooper, the ' mediastinum testis ' (fig. 138). This sep- 
 tum transmits the blood vessels of the gland, and contains, also, 
 the network of seminal ducts, called the rete testis, shown in 
 diagram 137. 
 
 From the mediastinum testis are given off in all directions a 
 number of slender fibrous cords, which traverse the interior of 
 
DISSECTION OF THE TESTIS. 
 
 583 
 
 Fig. 138. 
 
 Tunica 
 vasculosa. 
 
 the gland, and are attached to the inside of the tunica albuginea. 
 They serve to maintain the general shape of the testicle, to support 
 the numerous lobules of which its glandular substance is composed, 
 and to convey the blood vessels into it. These tie-beams (trabeculce 
 testis), as well as the mediastinum from which they proceed, are 
 readily seen on making a transverse 
 section through the gland (fig. 138). 
 
 Respecting the so-called 
 
 tunica vasculosa, nothing 
 
 more need be said than that 
 it consists of a multitude of fine blood 
 vessels, formed by the ramifications of 
 the spermatic artery, and held together 
 by delicate cellular tissue. It lines the 
 inner surface of the tunica albuginea, 
 and gives off vessels which run with the 
 fibrous cords into the interior of the 
 gland. 
 
 When the testicle is cut 
 structure* ^o, its interior looks soft 
 
 and pulpy, and of a reddish- 
 grey colour. It consists of an innume- 
 rable multitude of minute convoluted 
 tubes (tubuli seminiferi). For eco- 
 nomy of space they are arranged in 
 lobules, between four and five hundred * 
 
 in number, of various sizes, and contained in the compartments 
 formed by the fibrous cords proceeding from the mediastinum 
 testis. Only a few of these lobules are shown in diagram 138. 
 Though disposed in lobules, still they communicate with each 
 other, and thus form one vast network of tubes. The secretion 
 from them is carried off by some forty or fifty straight vessels 
 (vasa recta), which penetrate the mediastinum testis, and there 
 form a plexus of seminal tubes, termed the ' rete testis.' This lies 
 
 TRANSVERSE SECTION THROUGH 
 THE TESTICLE. 
 
 (Diagrammatic.) 
 
 1. Spermatic artery. 
 
 2. Vasdeferens. 
 
 3. Deferential artery. 
 
 4. Epididymis. 
 
 5. Mediastinum testis. 
 
 6. 6. Cavity of tunica vaginalis. 
 (The dots show the reflections of the 
 
 tunica vaginalis.) 
 
 * This estimate is according to Krause, Miiller's Archiv, fur Anat. 1837- 
 
584 DISSECTION OF THE TESTIS. 
 
 along the back of the gland. From the upper part of the rete 
 the secretion is carried away to the large end of the epididymis 
 by fifteen or twenty tubes, termed, { vasa efferentiaS These, after 
 forming a vast number of coils, termed ' coni vascidosij which 
 collectively constitute the globus major of the epididymis, ulti- 
 mately terminate, one after the other, in a single duct, the com- 
 mencement of the vas deferens. 
 
 Commencing, then, in the globus major of the epididymis, the 
 vas deferens descends, making a series of extremely tortuous coils, 
 which alone form the globus minor.* From the lower part of the 
 globus minor the vas deferens ascends, joins the other component 
 parts of the spermatic cord, passes through the inguinal canal, 
 winds round the back part of the bladder, and empties itself into 
 the prostatic part of the urethra. The length of the vas deferens 
 was estimated by Monro at upwards of thirty feet. The same 
 anatomist calculated that the semen, before it arrived at the vas 
 deferens, had to traverse a tube forty-two feet in length. 
 
 The spermatic cord is composed of the spermatic 
 vessels, nerves, and absorbents, of the vas deferens, with 
 the little deferential artery (a branch of the superior 
 vesical), of the cremaster muscle and the cremasteric artery. Its 
 coverings have been described with the anatomy of the parts of 
 hernia, p. 323. 
 
 The course of the spermatic arteries and veins have been de- 
 scribed in the dissection of the Abdomen, p. 352. The artery is 
 remarkably tortuous as it descends along the cord ; it enters the 
 back part of the testicle, and breaks up into a multitude of fine 
 ramifications, which spread out on the inner surface of the tunica 
 albuginea. The spermatic veins leave the testicle at its back part, 
 and, as they ascend along the cord, become extremely tortuous, 
 and form a plexus termed ' pampiniform.' It is usually stated 
 that these veins are destitute of valves ; and this fact is adduced 
 as one of the reasons for the occurrence of ' variocele.' But it is 
 certain that the larger veins do contain valves. 
 
 * A little blind duct, called vasculum abcrrans, is sometimes connected either to 
 the epididymis or the vas deferens. 
 
DISSECTION OF THE TESTIS. 585 
 
 The absorbents of the testicle terminate in the lumbar glands ; 
 hence these glands become affected in malignant disease of the 
 testicles. 
 
 The nerves of the testicle are derived from the sympathetic. 
 They run down from the abdomen with the spermatic arteries 
 (p. 356). This accounts for the stomach and intestines sympa- 
 thising so readily with the testicle, and for the constitutional 
 effects of an injury to it. 
 
 The testicle is originally developed in the lumbar 
 region, immediately below the kidneys ; and it is loosely 
 attached to the back of the abdomen by a fold of 
 peritoneum, termed the ' mesorchium,' along which its vessels and 
 nerves run up to it, as to any other abdominal viscus. From the 
 lower end of the gland there proceeds to the bottom of the scrotum, 
 a contractile cord termed the * gubernaculum testisS* By the 
 gradual contraction of this, the organ is brought into the scrotum. 
 It begins to slide down from the loins about the fifth month, 
 reaches the ring about the seventh, and about the ninth has 
 entered the scrotum. Its original peritoneal coat is retained 
 throughout; but, as it enters the inguinal canal, the peritoneal 
 lining of the abdomen is pouched out before it, and eventually 
 becomes the tunica vaginalis reflexa. Immediately after the 
 descent of the testis, its serous bag communicates with the abdo- 
 men, and in the lower animals continues to do so through life.f 
 But in the human subject the canal of communication soon begins 
 to close. It begins to close at the top first, and the closure is 
 generally complete in a child born at its full time.J The final 
 
 * Mr. Curling considers the gubernaculum testis to be a muscular cord. See his 
 Observations on the Structure of the Gubernaculum, and on the Descent of the Testis 
 in the Foetus: Medical Gazette, April 10, 1841. 
 
 t According to Professor Owen, the African orang outan (Simia troglodytes) is the 
 only exception to this rule. In this animal it is interesting to observe that the lower 
 extremities are more fully developed as organs of support, and there is a ligamentum 
 teres in the hip-joint. 
 
 \ According to Camper, the canal on the right side is nearly always open at birth, 
 whereas that on the left is nearly always closed. This fact explains the greater 
 frequency of hernia on the right side in children under one year old. Thus out of 
 
586 DISSECTION OF THE TESTIS. 
 
 purpose of this is to provide against the occurrence of ruptures, to 
 which man, from his erect attitude, is so much more exposed than 
 animals. At the end of the first month after birth, the canal is 
 entirely obliterated from the abdominal ring to the testis. Some- 
 times, however, this obliteration fails to take place, or is only 
 partial; hence may arise congenital hernia, or hydrocele. The 
 possible existence of a communication between the tunica vagi- 
 nalis and the peritoneal cavity of the abdomen, is one of the 
 reasons why hydroceles in infants are not treated by stimulating 
 injections. 
 
 3,014 cases of right and left inguinal hernia, seen at the City of London Truss Society, 
 2,269 occurred on the right side, and 745 on the left ; or in the proportion of 3 to 1. 
 
587 
 
 INDEX. 
 
 ABD 
 
 Abdomen, dissection of, 308 
 
 parts exposed on opening, 325 
 Abdominal muscles, 311 
 
 viscera, position of, 326 
 ABSORBENT GLANDS 
 
 axillary, 224 
 
 bronchial, 130 
 
 cervical, deep, 32 
 
 superficial, 16 
 
 concatenate, 32 
 
 of elbow, 235 
 
 femoral, 439 
 
 inguinal, deep, 440 
 
 superficial, 439 
 
 intercostal, 129 
 
 lumbar, 350 
 
 mammary, 104 
 
 mediastinal, 104 
 
 pelvic, 350 
 
 pharyngeal, 154 
 
 popliteal, 482 
 
 submaxillary, 35 
 
 thyroid, 32 
 Achillis, tendo, 487 
 Albinos, no pigment in, 561 
 Ampullae of semicircular canals, 575 
 Annulus ovalis, 134 
 Antrum pylori, 432 
 Aorta, arch of, 108 
 
 abdominal, 351 
 
 thoracic, 121 
 APONEUROSES 
 
 of abdominal muscles, 311 
 
 pharyngeal, 164 
 
 temporal, 85 
 
 scalp, of, 2 
 
 vertebral, 201, 271 
 Appendices epiploicse, 436 
 Appendix vermiformis, 327 
 
 ART 
 Arachnoid membrane of brain, 511 
 
 of cord, 545 
 fluid, 512 
 spaces, 512 
 of cord, 545 
 Arbor vitae of uterus, 417 
 
 of cerebellum, 543 
 Arciform fibres of medulla, 519 
 Aqueductus Fallopii, 79 
 Sylvii, 540 
 vestibuli, 575 
 Arantii corpus, 137 
 Arch, crural, 212 
 
 deep crural, 449 
 Arm, dissection of, 217 
 ARTERIES 
 
 alar thoracic, 225 
 
 anastomotica magna, of arm, 241 
 
 femoris, 464 
 angular, 76 
 aorta, arch of, 108 
 abdominal, 351 
 thoracic, 121 
 
 articular, of popliteal, 489 
 ascending cervical, 58 
 palatine, 38 
 pharyngeal, 48 
 auditory, 578 
 auricular anterior, 83 
 posterior, 48 
 axillary, 226 
 axis, cseliac, 337 
 thoracic, 221 
 thyroid, 58 
 
 azygos of popliteal, 489 
 basilar, 514 
 brachial, 238 
 brachio-cephalic, 110 
 bronchial, 130, 150 
 
588 
 
 INDEX. 
 
 ART 
 
 ARTERIES (continued) 
 bicipital, 230 
 buccal, 89 
 
 of bulb of urethra, 374 
 capsular, 351 
 common carotid, 27 
 right, 27 
 left, 28 
 carotid, left, 110 
 
 external, 45 
 internal, 95 
 
 carpal, anterior, 250, 252 
 
 posterior, 250, 252 
 
 centralis retinae, 184, 566 
 
 modioli, 576 
 cerebellar, inferior, 515 
 superior, 515 
 anterior, 515 
 cerebral, anterior, 513 
 middle, 513 
 posterior, 515 
 cervicalis ascendens, 58 
 
 profunda, 60 
 ciliary, anterior, 184 
 
 rsterior, 184 
 Willis, 515 
 
 circumflex, anterior, 229 
 posterior, 228 
 internal, 461 
 external, 462 
 circumflexa ilii, deep, 354 
 
 superficial, 310 
 choroid, anterior, 513 
 posterior, 515 
 cseliac axis, 337 
 colic-ilio, 342 
 
 middle, 342 
 right, 342 
 left, 343 
 
 comes nervi ischiatici, 478 
 mediani, 254 
 phrenici, 103 
 
 communicating anterior, 513 
 posterior, 513 
 coronary of the heart, 140 
 inferior, 76 
 superior, 76 
 
 coronaria ventriculi, 337 
 cremasteric, 322 
 crico-thyroid, 46 
 of crus penis, 374 
 cystic, 338 
 deep cervical, 60 
 deferential, 388 
 
 ART 
 
 ARTERIES (continued) 
 dental, inferior, 89 
 superior, 89 
 descending palatine, 89 
 digital of hand, 259 
 
 foot, 497 
 
 dorsal of foot, 471 
 dorsalis hallucis, 471 
 dorsales linguae, 44 
 dorsal of penis, 375 
 dorsalis scapulae, 228, 280 
 ethmoidal, 185 
 epigastric, deep, 322 
 
 superficial, 309 
 external carotid, 45 
 
 haemorrhoidal, 365 
 mammary, 227 
 maxillary, 38, 75 
 circumflex, 462 
 iliac, 354 
 facial, 38, 75 
 femoral, 459 
 frontal, 185 
 gastro-epiploica dextra, 337 
 
 sinistra, 339 
 glutaeal, 388, 476 
 helicine, 403 
 
 haemorrhoidal, superior, 382 
 middle, 382 
 inferior, 365 
 external, 365 
 hepatic, 337 
 hyoid, 44, 46 
 iliac, common, 353 
 external, 354 
 internal, 387 
 ilio-lumbar, 388 
 inferior dental, 89 
 
 mesenteric, 342 
 palatine, 38 
 infra-orbital, 82, 89 
 innominate, 110 
 intercostal aortic, 127 
 
 anterior, 103 
 perforating of, 103 
 intercosto-phrenic, 103 
 intercostal, superior, 60 
 internal mammary, 59 
 maxillary. 87 
 carotid, 95 
 iliac, 387 
 circumflex, 461 
 pudic, 374, 389, 479 
 interosseous, common. 252 
 
INDEX. 
 
 589 
 
 ART 
 ARTERIES (continued) 
 
 interosseous, anterior, 254 
 
 dorsal, of carpus, 290 
 palmar, 267 
 posterior, 289 
 recurrent, 289 
 ischiatic, 389, 479 
 labial, inferior, 76 
 lachrymal, 184 
 lateral, of the nose, 76 
 lateral sacral, 388 
 lingual, 44 
 lumbar, 352 
 magna pollicis, 267 
 malleolar, 471 
 mammary, internal, 59, 103 
 
 external, 227 
 masseteric, 89 
 maxillary, internal, 87 
 
 external, 38, 75 
 mediastinal, 103 
 medullary, of femur, 463 
 
 of humerus, 241 
 of tibia, 493 
 meningeal, 4 
 meningea media, 88 
 parva, 89 
 
 meningeal, posterior, 515 
 mental, 82 
 
 mesenteric, inferior, 342 
 superior, 341 
 metatarsal, 471 
 middle sacral, 390 
 nasal, 185 
 
 nasal, from internal maxillary, 90 
 obturator, 388, 465 
 
 abnormal course, 451 
 occipital, 47 
 cesophageal, 130 
 ophthalmic, 184 
 ovarian, 352 
 palatine, ascending, 94 
 
 descending, 89 
 palmar arch, deep, 258 
 
 superficial, 257 
 interosseous, 267 
 palmar, perforating, 267 
 palmaris profunda, 267 
 palpebral, 185 
 pancreatico-duodenalis, 337 
 pancreaticse parvse, 339 
 magna, 339 
 
 perforating, of plantar, 497 
 profunda, 463 
 
 ART 
 
 ARTERIES (continued) 
 
 perforating, of hand, 367 
 peroneal, 492 
 
 pharyngeal, ascending, 48, 96 
 phrenic, 351 
 plantar, external, 496 
 internal, 496 
 pollicis magna, 267 
 popliteal, 488 
 posterior auricular, 48 
 
 circumflex, 277 
 interosseous, 289 
 scapular, 59, 274 
 tibial, 492 
 
 princeps cervicis, 48, 209 
 profunda femoris, 461 
 
 superior, 239, 281 
 inferior, 241 
 perforating, of, 463 
 pterygoid, 89 
 pterygo-palatine, 90 
 pubic branch of epigastric, 322 
 obturator, 388 
 pudic, 374, 389, 479 
 
 deep external, 440 
 superficial, 309 
 pulmonary, 130 
 pyloric, 337 
 radial, 249, 290 
 
 recurrent, 250 
 radialis indicis, 267 
 ranine, 44 
 renal, 352 
 sacra media, 353, 390 
 
 lateralis, 388 
 septum nasi, artery of, 76 
 scapular, posterior, 59 
 sigmoidea, 343 
 spermatic, 352 
 
 in female, 352 
 spinal, anterior, 515 
 posterior, 515 
 splenic, 338 
 spheno-palatine, 90 
 sterno-mastoid, 46, 47 
 stylo-mastoid, 48 
 subclavian, 51 
 
 right, 51 
 left, 54, 111 
 sublingual, 44 
 submental, 38 
 
 subscapular, anterior, branch, 227 
 posterior, branch, 228 
 superficialis colli, 59, 274 
 
590 
 
 INDEX. 
 
 ART 
 ABTEEIES (continued) 
 
 superficial, of axilla, 223 
 superficial epigastric, 440 
 superficialis perinei, 366 
 volse, 250 
 
 circumflexa ilii, 440 
 superior dental, 89 
 
 intercostal, 60 
 laryngeal, 40 
 mesenteric, 341 
 profunda, 281 
 thyroid, 46 
 supra orbital, 184 
 
 scapular, 58, 273, 280 
 sural, 489 
 tarsal, 471 
 temporal, deep, 89 
 middle, 83 
 superficial, 83 
 thoracic axis, 221 
 alaris, 225 
 
 superior or short, 221 
 inferior or long, 227 
 thoracica acromialis, 221 
 humeraria, 221 
 thumb, dorsal, of, 291 
 thymic, 103 
 thyroid axis, 58 
 
 inferior, 58 
 superior, 46 
 middle, 31 
 tibial, anterior, 470 
 posterior, 492 
 recurrent, 470 
 tonsillar, 38 
 
 transversalis colli, 59, 274 
 faciei, 77 
 humeri, 58, 273 
 perinei, 366 
 tympanic, 88 
 ulnar, 251 
 
 ulnaris profunda, 258 
 ulnar, recurrent anterior, 252 
 posterior, 252 
 uterine, 413 
 vaginal, 413 
 vasa brevia, 339 
 vertebral, 57, 514 
 vesical, inferior, 388 
 middle, 388 
 superior, 388 
 Vidian, 90 
 Willis, circle of, 515 
 Appendix vermiformis, 327 
 
 BUR 
 
 Appendices epiploicae, 436 
 Arytenoid cartilages, 164 
 Auditory nerve, 527, 578 
 Auricle, left, 138 
 
 right, 133 
 
 Axilla, dissection of, 222 
 Axis, cseliac, 337 
 
 thoracic, 221 
 
 thyroid, 58 
 
 BACK 
 
 muscles of, 201 
 
 nerves of, 207, 268 
 
 vessels of, 209 
 
 muscles of, connected with arm, 268 
 Bell's nerve, 63, 226 
 Bichat, fissure of, 536 
 Bile-duct, 340 
 Bladder, gall-, 329, 425 
 Bladder, urinary structure of, 392 
 
 trigone of, 393 
 
 uvula of, 395 
 
 nerves of, 396 
 
 blood vessels of, 396 
 
 female, 411 
 
 position of, 382 
 
 ligaments of, 376, 379 
 Brachial plexus, 61, 230 
 BBAIN 
 
 dissection of, 528 
 
 arteries of, 513 
 
 membranes of, 511 
 
 peculiarities of circulation in, 516 
 
 general division of, 516 
 
 sinuses of, 6 
 
 parts at base of, 523 
 Bronchus, right, 145 
 
 left, 146 
 
 Brown Sequard, researches of, 551 
 Bulb of urethra, 404 
 of vagina, 407 
 Burns, falciform process of, 444 
 
 of the biceps (arm), 236 
 under ball of great toe, 493 
 under the carpus, 264 
 under deltoid, 277 
 over the elbow, 282 
 between the fingers, 292 
 under glutsens maximus. 475 
 over knuckles, 282 
 under latissimus dorsi, 270 
 over patella, 458 
 
INDEX. 
 
 591 
 
 BUR 
 BUESJE (continued) 
 
 tinder ligamentum patellae, 457 
 
 over pomum Adami, 163 
 
 tinder sartorius, 452 
 
 tinder semimembranosus, 484 
 
 between toes, 499 
 
 tinder subscapularis, 279 
 
 under tendo Achillis, 488 
 
 Csecal (ilio) valve, 437 
 Caecum, 327 
 
 Calamus scriptorius, 541 
 Calf, dissection of the, 485 
 CANALS, alimentary, 326 
 
 crural, 449 
 
 inguinal, 321 
 
 of Huguier, 574 
 
 of Petit, 568 
 
 of Schlemm or Fontana, 562 
 
 semicircular, 575 
 Caput coli, 327 
 Caput gallinaginis, 397 
 Carpus, bursal sac of, 264 
 Caruncula lacrymalis, 71 
 Cauda equina, 547 
 Central line of neck, 33 
 Cerebellum, 541 
 
 crura or peduncles of, 543 
 
 lobes of, 542 
 
 Cerebral nerves, origin of, 524 
 Cerebro-spinal fluid, 512 
 
 of cord, 545 
 Cerebrum, 520 
 
 convolutions of, 522 
 
 nomenclature of parts at the base of, 
 
 523 
 
 Chambers of eye, 562 
 Chest, dissection of, 101 
 Chordae Willisii, 7 
 
 vocales, 167 
 
 false, 167 
 
 tendineae, 135 
 
 tympani, 93, 195 
 Choroid coat of the eye, 559 
 Choroid plexus, 536 
 
 of fourth ventricle, 540 
 Chyli receptaculum, 122 
 Ciliary arteries, 184 
 
 body, 561 
 
 ligament, 561 
 
 muscle, 562 
 
 processes, 561 
 Clitoris, 405 
 
 DUC 
 
 Cochlea, 576 
 Colon, 327 
 
 ascending, 327 
 
 descending, 328 
 
 sigmoid flexure of, 328 
 
 transverse, 328 
 
 structure of, 436 
 Columnae carnese, 135 
 Commissures of the cerebrum, 538 
 
 of the cerebellum, 543 
 Conjunctiva oculi, 555 
 Cord, spermatic, 584 
 
 spinal, 544 
 Cornea, 558 
 Cornicula laryngis, 165 
 Corpus Arantii, 137 
 
 callosum, 528 
 
 cavernosum penis, 402 
 
 geniculatum extern um, 537 
 intern um, 537 
 
 Highmori, 582 
 
 luteum, 420 
 
 rhomboideum, 543 
 
 spongiosum, 402, 404 
 
 striatum, 533 
 Cotunnii, liquor, 577 
 Cowper's glands, 400 
 
 in female, 408 
 Cricoid cartilage, 163 
 Crico-thyroid membrane, 164 
 Crura cerebri, structure of, 554 
 
 cerebelli, 543 
 Crural arch, 446 
 Crural arch, deep, 449 
 Crural canal, 449 
 Crystalline lens, 568 
 
 Dartos, tunica scroti, 580 
 Deglutition, mechanism of, 161 
 Digastric triangle, dissection of, 35 
 DUCTS 
 
 arteriosus, 130 
 
 communis choledochus, 340, 425 
 
 communis ejaculatorius, 368 
 
 Cowper's, 400 
 
 cystic, 425 
 
 galactopherous, 579 
 
 hepatic, 340 
 
 lachrymal, 70, 198 
 
 of lachrymal gland, 180 
 
 nasal, 198 
 
 pancreatic, 344 
 
 parotid, 78 
 
592 
 
 INDEX. 
 
 DUG 
 DUCTS (continued) 
 
 prostatic, 397 
 
 of Kivinus, 43 
 
 seminal, 384 
 
 Steno's, 78 
 
 sublingual, 43 
 
 submaxillary, 37 
 
 thoracic, 55, 122 
 
 ureter or renal, 345, 384 
 
 venosus, 143 
 
 Wharton's, 37 
 Duodenum, 326, 343 
 Dura mater of brain, 5 
 
 arteries of, 4 
 
 sinuses of, 6 
 
 uses of, 5 
 
 Dura mater of spinal cord, 545 
 Duverney's glands, 408 
 
 EAR, dissection of the, 569 
 
 muscles of the, 2, 570 
 
 internal, 574 
 Endocardium, 133 
 Endolymph, 577 
 Epididymis, 581 
 Epiglottis, 165 
 Eustachian tube, 154 
 Eustachian valve, 135 
 Eye, dissection of, 555 
 EYELIDS, structure of, 68 
 
 cartilages of, 69 
 
 ligaments of, 69 
 
 tendon of, 67 
 
 nerves of, 69 
 
 glands of, 71 
 
 caruncula of, 71 
 
 Face, dissection of, 64 
 Fallopian tubes, 419 
 Fallopii aquseductus, 194 
 Falx cerebri, 5 
 
 cerebelli, 6 
 FASCIA 
 
 axillary, 223 
 
 buccal, 74 
 
 bucco-pharyngeal, 75 
 
 cervical, 17 
 
 costo-coracoid, 220 
 
 cribriform, 443 
 
 of forearm, 246 
 
 forearm, back of, 283 
 
 iliac, 349 
 
 infundibuliform, 321 
 
 FASCIA (continued) 
 
 lata, 442 
 
 of the leg, 467 
 
 mammary, 579 
 
 of metacarpus, 284 
 
 obturator, 378 
 
 orbital, 177 
 
 palmar, 256 
 
 pelvic, 376 
 
 in female, 411 
 
 perineal, superficial, 365 
 deep, 366 
 
 pharyngeal, 151 
 
 plantar, 493 
 
 popliteal, 480 
 
 prsevertebral, 18 
 
 propria of hernia, 449 
 
 spermatic, 318 
 
 superficial, of abdomen, 308 
 perineum, 365 
 thigh, 438 
 
 temporal, 85 
 
 thoracic, 121 
 
 transversalis, 320 
 
 of upper arm, 235 
 
 FlBRO-CARTILAGES 
 
 of the ear, 570 
 
 eyelids, 69 
 intervertebral, 211 
 interarticular, of clavicle, 295 
 jaw, 217 
 knee, 505 
 pubes, 500 
 wrist, 302 
 of the nose, 195 
 
 trachea, 146 
 Filutn terminale, 546 
 Flexor tendons in the palm, 262 
 
 sheaths of the palm, 262 
 Foetal circulation, 143 
 Foot, dissection of sole of, 493 
 Foramina 
 
 ovale of heart, 134 
 of Monro, 535 
 
 Soemmerring, 565 
 Thebesius, 135 
 Winslow, 323 
 Forearm, dissection of, 245 
 
 back of, dissection of, 283 
 Fornix, 534 
 Fossa navicularis, 400 
 
 ischio-rectal, 364, 375 
 Frsenum linguse, 173 
 preputii, 402 
 
INDEX. 
 
 593 
 
 GAL 
 
 Galen, veins of, 536 
 Gall-bladder, 329, 425 
 
 duct of, 425 
 GANGLIA 
 
 of Andersch, 193 
 
 Arnold's, 194 
 
 cardiac, 131 
 
 cervical, of sympathetic, 99 
 
 thoracic, of sympathetic, 126 
 
 lumbar, of sympathetic, 356 
 
 pelvic, of sympathetic, 392 
 
 Cloquet's, 190 
 
 impar, 99 
 
 jugular, 193 
 
 lenticular, 185 
 
 Gasserian, 526 
 
 Meckel' s, 189 
 
 naso-palatine, 190 
 
 olfactory, 525 
 
 ophthalmic or lenticular, 185 
 
 otic or Arnold's, 192 
 
 petrous, 193 
 
 semilunar, 345 
 
 spheno-palatine, 189 
 
 of spinal nerves, 549 
 
 submaxillary, 43 
 
 of Kibes, 99 
 
 Gimbernat's ligament, 446 
 GLANDS, SECRETING 
 
 agminatse, 435 
 
 anal, 363 
 
 Bartholin's, 408 
 
 of Brunn, 435 
 
 Cowper's, 398, 374 
 
 in female, 408 
 
 Duverney's, 408 
 
 lachrymal, 180 
 
 of Lieberkiihn, 435 
 
 lingual, 175 
 
 mammary, 579 
 
 Meibomian, 71 
 
 mesenteric, 341 
 
 molar, 75 
 
 Naboth's, 417 
 
 oesophageal, 124 
 
 of Pacchioni, 7 
 
 palatine, 160 
 
 pancreas, 344 
 
 parotid, 77 
 
 socia parotidis, 78 
 
 Peyer's, 435 
 
 pineal, 538 
 
 pituitary, 523 
 
 prostate, 385 
 
 ILE 
 GLANDS, SECRETING (continued) 
 
 solitary, 436 
 
 sublingual, 43 
 
 submaxillary, 37 
 
 testis, 581 
 
 thyroid, 29 
 
 trachea!, 146 
 Glans penis, 402 
 Glisson's capsule, 340, 422 
 Glottis, 166 
 Glutseal region, 473 
 
 cutaneous nerves of, 473 
 Graafian vesicles, 420 
 Gubernaculum testis, 585 
 Gyrus fornicatus, 522 
 
 Hamstring muscles, 482 
 HEART 
 
 dissection of, 132 
 
 muscular fibres of, 141 
 
 peculiarities of foetal, 1 42 
 
 position and form of, 113, 116 
 
 rings of, 139 
 
 valves of, position of, 117 
 
 nerves of, 131 
 
 vessels of, how attached, 139 
 Helicotrema, 576 
 HERNIA 
 
 inguinal, dissection of parts concerned, 
 316 
 
 coverings of, 323 
 
 congenital, 323 
 
 changes produced by age, 325 
 
 infantile, 323 
 
 nomenclature of, 322 
 
 seat of stricture, 324 
 
 femoral, parts concerned in, 445 
 
 coverings of, 450 
 
 fascia propria of, 450 
 
 seat of stricture, 451 
 Herophyli, torcular, 10 
 Hey's ligament, 445 
 Hippocampus major, 535 
 minor, 535 
 Horner's muscle, 187 
 Housten's folds in rectum, 438 
 Humor, aqueous, 566 
 
 vitreous, 567 
 Hunter's canal, 460 
 Hyaloid membrane, 567 
 Hymen, 408 
 
 Ileum intestinum, 327 
 
 QQ 
 
594 
 
 INDEX. 
 
 ILE 
 
 L'eum, glands of, 435 
 Ileo-csecal valve, 437 
 Icfundibulum, 523 
 Inguinal canal, 321 
 
 boundaries of, 321 
 
 rings of, 317, 321 
 Intestinal canal, course of, 326 
 Intestines, structure of small, 435 
 
 glands of, 435 
 
 structure of large, 436 
 Iris, 562 
 
 Ischio-rectal fossa, 364, 375 
 Isthmus faucium, 156 
 Iter a tertio ad quartum ventriculum, 538 
 
 Jejunum, 327 
 
 glands of, 435 
 JOINTS 
 
 acromio- clavicular, 296 
 
 ankle, 507 
 
 carpal, 303 
 
 carpo-metacarpal, 305 
 
 crico-thyroid, 172 
 
 elbow, 298 
 
 of fingers, 306 
 
 of the foot, 509 
 
 hip, 501 
 
 intercarpal, 304 
 
 knee, 503 
 
 of lower jaw, 216 
 
 metacarpal, 305 
 
 metatarsal, 510 
 
 occipi to- spinal, 213 
 
 of pelvis, 500 
 
 of the ribs, 215 
 
 shoulder, 297 
 
 of the spine, 210 
 
 radio-carpal or wrist, 301 
 
 radio-ulnar, inferior, 301 
 
 sterno-clavicular, 294 
 
 tarsal, 509 
 
 tibio-fibular, 507 
 
 of the toes, 511 
 
 wrist, 301 
 
 Kidney, relations of, 344 
 situation of, 330 
 structure of, 427 
 
 labia majora, 405 
 
 LIG 
 
 Labia minora, 405 
 Labyrinth, membranous, 577 
 
 osseous, 574 
 Lachrymal sac, 198 
 
 duct, 198 
 
 Lacteal vessels, 122 
 Lac\;nse of urethra, 400 
 Lamina cinerea, 523 
 
 spiralis, 576 
 Lamina cribrosa oculi, 557 
 
 fusca, 557 
 
 Laryngotorny, observations on, 33 
 Larynx, dissection of, 162 
 blood vessels of, 171 
 muscles of, 168 
 nerves of, 171 
 
 sacculus of, 166 ," 
 
 ventricle of, 166 
 vocal cords of, 167 
 Leg, dissection of the front of, 466 
 Lens, crystalline, 568 
 
 capsule of, 568 
 Lenticular ganglion, 185 
 LIGAMENTS 
 
 accessory, of hip, or ilio-femoral, 502 
 
 humerus, 297 
 acromio-clavicular, 296 
 alaria, 505 
 
 annular, of the ankle, 467 
 anterior, 467 
 external, 468 
 internal, 468, 491 
 annular, anterior, of carpus, 260 
 posterior, of carpus, 283 
 annular, of radius, 300 
 arcuatum externum et internum, 346 
 of atlas and axis, 214 
 broad, of uterus, 409 
 calcaneo-cuboid, 510 
 
 scaphoid, 509 
 ciliary, 561 
 
 conoid and trapezoid, 296 
 coracoid, 296 
 coraco-acromial, 296 
 coraco-clavicular, 296 
 coraco-humeral (accessory), 297 
 coronary of liver, 329 
 coronary of knee, 506 
 costo-clavicular, 295 
 transverse, 215 
 cotyloid of hip, 503 
 crucial, 505 
 denticulatum, 546 
 external lateral, of ankle, 508 
 
INDEX. 
 
 595 
 
 LIG 
 LIGAMENTS (continued) 
 
 external lateral, of elbow, 299 
 jaw, 216 
 knee, 504 
 wrist, 301 
 falciform, 329 
 Gimbernat's, 446 
 glenoid, of fingers, 306 
 toes, 511 
 shoulder, 298 
 glosso-epiglottidean, 173 
 Key's, 445 
 
 hyo-epiglottidean, 165 
 ilio-femoral, 502 
 ilio-lumbar, 501 
 interclavicular, 294 
 internal lateral, of ankle, 507 
 elbow, 299 
 jaw, 93, 216 
 knee, 504 
 wrist, 301 
 
 interosseous, of leg, 507 
 arm, 300 
 carpus, 303 
 forearm, 300 
 foot, 510 
 metacarpus, 305 
 tarsus and metatarsus, 
 
 510 
 
 interspinous, 211 
 intertransverse, 213 
 lateral, of liver, 329 
 
 bladder, 379 
 latum pulmonis, 118 
 mucosum, 505 
 nuchse, 200, 269 
 oblique, of radius, 300 
 occiput, 213 
 odontoid or cheek, 214 
 orbicular, of radius, 300 
 of the ovary, 409 
 palpebral, 69 
 patellae, 457 
 of pelvis, 500 
 Poupart's, 312 
 posticum Winslowii, 504 
 pterygo -maxillary, 73 
 of pubes, 500 
 of the ribs, 215 
 round, of liver, 329 
 hip, 502 
 uterus, 409 
 
 sacro-iliac symphysis, 501 
 sacro-ischiatic, 501 
 
 MAS 
 
 LIGAMENTS (continued) 
 of spine, 210 
 stellate, 215 
 sterno-clavicular, 294 
 stylo-hyoid, 94 
 stylo-maxillary, 39 
 subflava, 211 
 sub-pubic, 500 
 suspensory, of head, 214 
 liver, 329 
 penis, 402 
 spleen, 330 
 sympyhsis pubis, 500 
 
 sacro-iliac, 501 
 of tarsal cartilages, 69 
 tarsal, 509 
 teres, of hip, 502 
 thyro-epiglottidean, 165 
 thyro-hyoid, anterior, 162 
 
 lateral, 162 
 tibio-fibular, 507 
 transverse, of atlas, 214 
 fingers, 257 
 hip, 503 
 knee, 506 
 metacarpal, 291 
 trapezoid and conoid, 296 
 triangular, of radius, 302 
 urethra, 369 
 Linea alba, 315 
 
 semilunaris, 314 
 Linese transversse, 314 
 Liquor Cotunnii, 577 
 
 Morgagni, 569 
 Liver, position of, 329 
 
 anatomy of, 421 
 Locus cseruleus, 541 
 niger, 554 
 
 perforatus antieus, 523 
 posficus, 523 
 LUNGS 
 
 constituents of root of, 132 
 lobules of, 147 
 nerves of, 125, 150 
 position and form of, 119 
 structure of, 144 
 Lunula of aortic valves, 137 
 
 Malpighian corpuscles, 429 
 of kidney, 429 
 spleen, 427 
 
 Mammary gland, dissection of, 579 
 Mastication, muscles of, 82 
 
 QQ 2 
 
596 
 
 INDEX. 
 
 MEA 
 
 Meatus auditorius externus, 571 
 Meatus urinarius, 406 
 MEDIASTINUM 
 anterior, 104 
 middle, 105 
 posterior, 105, 121 
 testis, 582 
 
 Medulla oblongata, 516 
 structure of, 551 
 arciform fibres of, 553 
 Meibomian glands, 71 
 Membrana Jacobi, 565 
 hyaloidea, 567 
 limitans, 566 
 pupillaris, 564 
 tympani, 572 
 
 Membranes of the brain, 511 
 cord, 545 
 
 Membranous labyrinth, 577 
 Meningeal arteries, anterior, 5 
 middle, 4 
 parva, 5 
 posterior, 5 
 Mesentery, 327, 334 
 Meso-csecum, 334 
 
 colon, transverse, 332 
 rectum, 360 
 Mesorchium, 585 
 Mitral valve, 139 
 Modiolus, 576 
 Monro, foramen of, 535 
 Mons Veneris, 405 
 Morgagni, sinus of, 154 
 
 liquor of, 569 
 MUSCLES 
 
 abductor minimi dig. manus, 266 
 pollicis manus, 265 
 
 ped., 494 
 min. dig., 495 
 accelerator urinse, 368 
 accessorius, 202 
 adductor pollicis manus, 265 
 
 ped., 498 
 
 adductors of thigh, 453 
 brevis, 455 
 longus, 454 
 magnus, 455 
 anconeus, 287 
 arytenoideus, 169 
 aryteno-epiglottideus, 170 
 attollens aurem, 2 
 attrahens aurem, 3 
 azygos uvulse, 157 
 biceps flexor cubiti, 236 
 
 MUS 
 
 MUSCLES (contn 
 
 biceps flexor cruris, 482 
 brachialis anticus, 238 
 buccinator, 73 
 cervicalis ascendens, 203 
 ciliary of the eye, 562 
 
 eyelid, 67 
 
 circumflexus or tensor palati, 158 
 coccygeus, 387 
 cochlearis, 576 
 complexus, 204 
 compressor nasi, 72 
 
 urethrse, 372 
 
 female, 406 
 
 constrictor superior, of pharynx, 153 
 middle, 153 
 inferior, 153 
 coraco-brachialis, 237 
 corrugator supercilii, 68 
 cremaster, 318 
 
 crico-arytenoideus lateralis, 170 
 posticus, 169 
 crico-thyroid, 168 
 cruraeus, 457 
 
 sub-, 457 
 deltoid, 275 
 depressor anguli oris, 66 
 
 labii inferioris, 66 
 superioris, 73 
 alee nasi, 73 
 septi narium, 66 
 diaphragm, 345 
 digastricus, 35 
 
 dilatator narium anterior, 73 
 posterior, 73 
 erector clitoridis, 406 
 penis, 369 
 spinse, 202 
 
 extensor communis dig. pedis, 468 
 carp. rad. long., 285 
 
 brevior, 285 
 communis digit., 285 
 digiti minimi, 286 
 carpi ulnaris, 286 
 indicis, 288 
 brevis dig. pedis, 471 
 proprius pollicis pedis, 468 
 ossis metac. pol., 288 
 primi interned, pol., 288 
 secundi interned., 288 
 extensors of thigh, 456 
 
 triceps, 457 
 external oblique, 312 
 flexor brevis min. dig. man., 266 
 
INDEX, 
 
 597 
 
 MUS 
 MUSCLES (continued) 
 
 flexor brevis min. dig. ped., 498 
 dig. ped., 495 
 pollicis manus, 265 
 pollicis ped., 498 
 carpi radialis, 247 
 ulnaris, 248 
 longus dig. pedis, 490 
 
 pollicis pedis, 490 
 pollicis, 254 
 
 ossis metacarpi pollicis, 265 
 profundus digitor., 253 
 sublimis digit., 248 
 gastrocnemius, 486 
 gemelli, 477 
 genio-hyoideus, 40 
 genio-hyo-glossus, 42 
 glutseus maximus, 474 
 medius, 475 
 minimus, 475 
 gracilis, 454 
 hamstring, 482 
 hyo-glossus, 41 
 iliacus internus, 349 
 indicator, 288 
 infra spinatus, 278 
 intercostal, 127 
 internal oblique, 313 
 interosseous, palmar, 293 
 
 of the foot, 499 
 interspinales, 206 
 intertransversales, 206 
 latissimus dorsi, 225, 270 
 laxator tympani, 574 
 levator ani, 386 
 leva tor anguli scapulae, 272 
 levatores costarum, 206 
 levator menti, 66 
 levator palpebrse, 69, 180 
 levator labii superioris alaeque nasi, 72 
 labii superioris, 72 
 anguli oris, 72 
 longissimus dorsi, 203 
 longus colli, 209 
 lumbricales, in palm, 264 
 lumbricales pedis, 496 
 masseter, 84 
 multifidus spinse, 205 
 mylo-hyoideus, 39 
 naso-labialis, 66 
 
 obliquus externus abdominis, 312 
 internus abdominis, 313 
 inferior capitis, 207 
 superior capitis, 207 
 
 MUS 
 MUSCLES (continued) 
 
 obliquus inferior oculi, 186 
 superior oculi, 181 
 occipito-frontalis, 2 
 obturator externus, 477 
 internus, 476 
 omo-hyoid, 24, 273 
 opponens digiti minimi, 266 
 opponens pollicis manus, 265 
 orbicularis oculi, 67 
 oris, 65 
 
 palpebrarum, 67 
 palato-glossus, 158 
 
 pharyngeus, 158 
 palmaris brevis, 256 
 longus, 247 
 papillares, 135, 139 
 pectinati, 133, 138 
 pectineus, 454 
 pectoralis major, 218 
 minor, 225 
 peroneus brevis, 472 
 longus, 472 
 tertius, 469 
 plantaris, 487 
 platysma myoides, 1 3 
 popliteus, 490 
 pronator quadratus, 254 
 prsevertebral, 209 
 pronator radii teres, 247 
 psoas magnus, 348 
 
 parvus, 349 
 pterygoid, external, 86 
 internal, 87 
 pyramidalis nasi, 68 
 pyriformis, 476 
 quadratus femoris, 477 
 quadratus lumborum, 350 
 quadratus menti, 66 
 rectus abdominis, 313 
 rectus capitis anticus major, 210 
 minor, 210 
 rectus capitis lateralis, 207 
 
 posticus major, 206 
 minor, 206 
 recti of the eye, 181 
 rectus femoris, 456 
 retrahens aurem, 3 
 risorius, 65 
 
 rhomboideus major, 272 
 minor, 272 
 rotatores spinse, 205 
 sacro-lumbalis, 202 
 Santorini's, 65 
 
598 
 
 INDEX. 
 
 MUS 
 
 MUSCLES (continued) 
 sartorius, 452 
 scalenus anticus, 50 
 medius, 50 
 posticus, 50 
 semimembranosus, 483 
 semispinalis colli, 205 
 dorsi, 205 
 
 semitendinosus, 483 
 serratus magnus, 226, 274 
 
 posticus inferior, 201 
 
 superior, 200 
 soleus, 487 
 sphincter ani, cutaneous, 365 
 
 internal, 436 
 sphincter vaginae, 407 
 spinalis dorsi, 204 
 splenius capitis, 201 
 
 colli, 201 
 stapedius, 574 
 sterno-cleido mastoideus, 20 
 sterno-hyoid, 24 
 
 thyroid, 24 
 stylo-glossus, 42 
 hyoideus, 36 
 glossus, 94 
 pharyngeus, 94 
 subanconeus, 281 
 subclavius, 220 
 subcruraeus, 457 
 subscapularis, 279 
 supinator radii brevis, 289 
 loiigus, 249 
 supra spinatus, 279 
 temporal, 85 
 
 tensor fasciae femoris, 455 
 tensor tarsi, 187 
 
 tympani, 574 
 palati, 158 
 teres major, 225, 278 
 
 minor, 278 
 
 thyro-arytenoideus, 170 
 thyro-hyoid, 26 
 tibialis anticus, 468 
 posticus, 491 
 trachelo-mastoid, 203 
 transversalis abdominal! s, 313 
 colli, 203 
 pedis, 498 
 
 trans versus perinei, 369 
 transverso-spinalis, 205 
 trapezius, 269 
 triangularis sterni, 103 
 triceps extensor cubiti, 244, 280 
 
 KER 
 MUSCLES (continued) 
 
 triceps extensor femoris, 457 
 vastus externus, 457 
 internus, 457 
 zygoma ticus major, 66 
 minor, 66 
 
 Naboth, glands of, 417 
 
 ovula, 417 
 Nasal duct, 198 
 Nates and testes, 539 
 Neck, dissection of, 13 
 NERVES 
 
 accessorius, 21 
 
 origin of, 527 
 
 accessory, of obturator, 358 
 anterior crural, 358, 464 
 dental, 188 
 thoracic, 222 
 auditory, 527, 578 
 auricular, 84 
 
 of Arnold, 194 
 auriculo-parotidean, 16 
 axillary plexus of, 230 
 Bell's, 63 
 
 brachial plexus of, 61, 230 
 buccal, inferior maxillary of, 91 
 buccal branches of facial, 8 1 
 cardiac, 100, 125 
 
 plexus, 131 
 of pneumogastric, 98 
 cerebral, origin of, 524 
 cervical branch of facial, 1 7 
 cervico-facial, 80 
 cervical plexus of, 49 
 chorda tympani, 93, 195 
 ciliary, long, 183 
 short, 185 
 coccygeal, 390 
 communicantes noni, 26, 49 
 circumflex, 232, 277 
 communicans peronei, 486 
 poplitei, 486 
 cranial, exit of, 10 
 descendens noni, 29 
 dental, anterior, 188 
 inferior, 92 
 posterior, 188 
 digital, of median, 260 
 
 of ulnar, 259 
 eighth pair of, 192, 527 
 external cutaneous, of arm, 243 
 leg, 467 
 
INDEX. 
 
 599 
 
 NER 
 
 NERVES (continued) 
 
 external cutaneous, of musculo-spiral, 
 
 233 
 
 thigh, 357 
 external laryngeal, 98 
 
 respiratory, 63, 226 
 
 saphenous, 486 
 facial, 79 
 
 facial, cervical branch of, 17 
 fifth pair of, 526 
 first pair of, 524 
 fourth or pathetic, 179, 526 
 frontal, 179 
 genito- crural, 311, 357 
 glosso-pharyngeal, 94, 527 
 glutseal superior, 390, 476 
 great ischiatic, 391, 477, 485 
 
 occipital, 3 
 
 petrosal, 190, 195 
 gustatory, 43, 93 
 hypo-glossal, 42, 528 
 ilio-hypogastric, 311, 356 
 
 inguinal, 311, 356 
 inferior laryngeal, 125, 98 
 inferior maxillary, 90 
 infra-orbital, 82 
 
 infra-orbital branches of facial, 80 
 infra trochlear, 183 
 intercostal, 129 
 
 intercostal, cutaneous branches of, 218 
 intercosto-humeral, 223 
 internal cutaneous, of arm, 233 
 lesser cutaneous, of arm, 233 
 internal cutaneous, of thigh, 441 
 interosseous, anterior, 254 
 posterior, 290 
 ischiatic, great, 477, 485 
 
 lesser, 391, 478 
 Jacobson's, 193 
 labial, 82 
 lachrymal, 170 
 of Lancisi, 529 
 laryngeal, inferior, 98, 125 
 
 recurrent, 98, 125 
 laryngeal, superior, 98 
 external, 98 
 
 lesser ischiatic, 391, 478 
 petrosal, 191, 195 
 long ciliary, 183 
 long pudendal, 366 
 long saphenous, 464, 466 
 lumbar plexus, 356 
 lum bo-sacral, 357 
 malar, 179 
 
 NER 
 NERVES (continued) 
 
 malar branches of facial, 80 
 
 masseteric, 91 
 
 median, 242, 253 
 
 mental, 82 
 
 middle cutaneous, of thigh, 441 
 
 molles, 76, 100 
 
 motores oculi, 526 
 
 musculo-cutaneous, of arm, 243 
 
 leg, 467 
 
 musculo-spiral or radial, 244 
 mylo-hyoidean, 39, 93 
 maxillary, inferior, 90 
 
 superior, 187 
 nasal, 82 
 
 nasal branch of ophthalmic, 183 
 nasal, from spheno-palatine ganglion, 
 
 190 
 
 naso-lobular, 65, 183 
 naso-palatine, 190 
 ninth pair or hypoglossal, 528 
 obturator, 358, 465 
 
 accessory, of, 358 
 occipital, great, 3 
 small, 4 
 
 olfactory, 199, 524 
 optic, 184, 525 
 
 ophthalmic branch of fifth, 178 
 orbital of superior maxillary, 1 87 
 palatine, 189 
 palmar, of median, 253 
 palpebral, 82 
 pes anserinus, 80 
 perforans Casserii, 243 
 peroneal, 472 
 petrosal, great, 190, 195 
 petrosal, lesser, 191, 195 
 phrenic, 51, 111 
 
 difference between right and 
 
 left, 111 
 plantar, external, 497 
 
 internal, 497 
 pneumogastric, 96, 527 
 in the chest, 124 
 at base of skull, 194 
 popliteal, 480 
 portio dura, 79, 194, 527 
 
 mollis, 527 
 
 posterior auricular, 80 
 posterior dental, 188 
 
 interosseous, 290 
 tibial, 493 
 saphenous, 486 
 posterior scapular, 272 
 
600 
 
 INDEX. 
 
 NER 
 
 NERVES (continued) 
 pterygoid, 91 
 pudic, 375, 391 
 pulmonary, plexus of, 125 
 radial, 250 
 
 below the elbow, 251 
 recurrent, laryngeal, 98, 125 
 rhomboid, 63 
 sacral plexus of, 390 
 saphenous, external, 486 
 
 long, 464 
 seventh, 527 
 sixth, 186, 527 
 spermatic plexus of, 356, 585 
 spinal, accessory, 272 
 origin of, 549 
 spheno-palatine, 190 
 splanchnic, great, 126 
 lesser, 127 
 smallest, 127 
 subcutaneous malse, 187 
 subscapular, 232 
 superficial s colli, 17 
 
 perinei, 366 
 superior laryngeal, 47 
 
 maxillary, 187 
 supra clavicular, 218 
 orbital, 179 
 trochlear, 179 
 scapular, 63 
 
 sympathetic, in the neck, 99 
 in chest, 126 
 lumbar portion, 353 
 pelvic portion, 391 
 in penis, 392 
 temporal, to muscle, 91 
 superficial, 83 
 temporo-auricular, 83, 92 
 
 facial, 80 
 
 thigh, cutaneous, of, 441 
 tibial, anterior, 470 
 posterior, 493 
 
 third or motor oculi, 186, 526 
 tympanic, 193 
 ulnar, 243 
 
 deep palmar branch of, 259, 267 
 Vidian, 190 
 of Wrisberg, 233 
 Nipple, 579 
 NOSE 
 
 dissection of, 195 
 blood vessels of, 199 
 boundaries of, 197 
 cartilages of, 195 
 
 PER 
 NOSE (continued) 
 
 interior of, 196 
 
 meatus of, 197 
 
 mucous membrane of, 198 
 
 posterior openings of, 156 
 
 veins of, 199 
 
 Nuchae, ligamentum, 200, 269 
 Nymphse, 404 
 
 (Esophagus, 123 
 
 Olivary bodies or olives, 518 
 
 OMENTUM 
 
 gastro-splenic, 330, 335 
 
 great, 334 
 
 gastro-hepatic, 334 
 
 lesser, 334 
 ORBIT 
 
 dissection of, 177 
 
 fascia, 177 
 
 periosteum, 177 
 Os-hyoides, 162 
 Os tincse, 413 
 uteri, 413 
 Otolithes, 577 
 Ovaries, 419 
 
 Pacchioni, glands of, 7 
 Pacini, corpuscles of, 261 
 PAIATE 
 
 arches of, 157 
 
 hard, 160 
 
 soft, 156 
 
 Palm, dissection of, 255 
 Pancreas, situation of, 330 
 relations of, 344 
 Parotid gland, 77 
 
 Patella, structures covering the, 458 
 Pelvic viscera, side view of male, 376 
 Pelvis, dissection of male, 359 
 
 female, 409 
 
 side view of female, 410 
 Penis, absorbents of, 404 
 
 anatomy of, 401 
 
 corpus cavernosum, 402 
 
 crus, 402 
 PENIS 
 
 corpus spongiosum, 402 
 
 glans, 402 
 
 nerves of, 404 
 Pericardium, 113 
 
 objects seen when laid open, 116 
 Peri-lymph of the internal ear, 577 
 
INDEX. 
 
 601 
 
 PER 
 
 Perineum, dissection of male, 362 
 female, 405 
 
 central tendon of, 366 
 Peritoneum, 331 
 
 lesser cavity of, 333 
 Peritoneum in female pelvis, 410 
 Pes anserinus, 80 
 Petit, canal of, 568 
 Peyer's glands, 435 
 Pharynx, dissection of, 150 
 
 aponeurosis of, 154 
 
 muscles of, 153 
 
 nerves of, 95 
 Pia mater, 513 
 
 of cord, 546 
 
 Pigmentum nigrum, 660 
 Pinseal gland, 538 
 Pinna of the ear, 570 
 Platysma myoides, 13 
 Pleura, 118 
 PLEXUS OF NERVES 
 
 axillary, 230 
 
 brachial, 61, 230 
 
 cardiac, 131 
 
 carotid, 13 
 
 cavernous, 13 
 
 cervical, 49 
 
 cervical superficial, 16 
 
 coronary, 132 
 
 guise, 125 
 
 hsemorrhoidal, 356 
 
 hypogastric, 356 
 
 lumbar, 356 
 
 oesophageal, anterior, 97 
 posterior, 97 
 
 cesophageal, 125 
 
 pharyngeal, 95 
 
 prostatic, 392 
 
 pulmonary, 125 
 
 sacral, 390 
 
 solar, 336 
 
 spermatic, 356 
 
 uterine, 392 
 
 vaginal, 392 
 
 vesical, 392 
 Pomum Adami, 163 
 Pons Varolii, 520 
 
 structure of, 554 
 Popliteal space, 479 
 
 boundaries of, 480 
 Portio dura, 79 
 Pouch, recto-vaginal, 410 
 
 rocto-vesical, 379 
 Poupart's ligament, 446 
 
 SCR 
 
 Prsecordial region, 116 
 Preputium, 401 
 
 clitoridis, 405 
 
 Processus a cerebello ad testes, 546 
 Promontory of tympanum, 572 
 Prostate, 396 
 
 structure of, 396 
 
 veins about, 385 
 Pterygo-maxillary region, 85 
 Puncta lachrymalia, 70 
 Pupil of eye, 563 
 Pylorus, 432 
 
 antrum of, 432 
 Pyramid in the ear, 574 
 Pyramids, anterior, 517 
 posterior, 519 
 
 Keceptaculum chyli, 122 
 Kecto-vesical pouch, 360 
 Rectum, 328, 360 
 
 relations of, 381 
 
 meso-rectum, 381 
 
 blood vessels of, 382 
 
 folds in, 438 
 Reil, island of, 522 
 
 fillet of, 553 
 Eenal capsule, situation of, 331 
 
 structure of, 430 
 Restiform bodies or tracts, 518 
 Kete testis, 583 
 
 mirabile of Gralen, 516 
 Retina, 564 
 Rima glottidis, 166 
 Rings, external abdominal, 317 
 
 internal abdominal, 321 
 
 femoral, 449 
 
 fibrous, of the heart, 139 
 Rolando, arciform fibres of, 519 
 
 Saccule of the labyrinth, 577 
 
 Sac, lachrymal, 198 
 
 Saphenous opening of fascia lata, 443 
 
 SCALP 
 
 aponeurosis of, 2 
 
 arteries of, 1 
 
 absorbents of, 4 
 
 dissection of, 1 
 
 nerves of, 3 
 Scarpa's triangle, 452 
 Schneiderian membrane, 198 
 Sclerotic coat of the eye, 556 
 Scrotum, structure of, 580 
 
 R R 
 
602 
 
 INDEX. 
 
 SCR 
 
 Scrotum, septum of, 580 
 Semicircular canals, 575 
 Septum lucichim, 533 
 
 pectiniforme, 403 
 SINUS 
 
 of aorta, 108 
 
 coronary, 140 
 
 of dura mater, 6 
 
 cavernous, 8, 12 
 
 circular, 9 
 
 inferior longitudinal, 8 
 
 lateral, 8 
 
 occipital, 9 
 
 petrosal, 9 
 
 straight, 8 
 
 superior longitudinal, 7 
 
 transverse, 9 
 
 circularis iridis, 562 
 
 of Morgagni (pharyngeal), 154 
 
 of Valsalva, 108 
 Sheath of femoral vessels, 448 
 Shoulder, dissection of, 275 
 Socrates, his description of the eyelids, 72 
 Soemmerring, foramen of, 565 
 Spermatic cord, 584 
 Spheno-maxillary region, 82 
 Spigelii lobulus, 422 
 Spinal cord, dissection of, 544 
 
 blood vessels of, 551 
 columns of, 548 
 fissures of, 547 
 fluid of, 545 
 membranes of, 545 
 veins of, 544 
 Spinal nerves, origin of, 549 
 
 ganglia of, 549 
 Spine, ligaments of, 210 
 Spleen, position of, 330 
 
 structure of, 426 
 Steno's duct, 78 
 Stomach, position of, 326 
 
 blood vessels of, 338 
 
 structure of, 433 
 Sublingual salivary gland, 43 
 Submaxillary region, 35 
 
 ganglion, 43 
 
 gland, 37 
 Sympathetic nerve, 99 
 
 in the neck, 99 
 chest, 126 
 abdomen, 353 
 pelvis, 391 
 Symphysis pubis, 500 
 
 sacro-iliac, 501 
 
 TYM 
 Tsenia hippocampi, 535 
 
 semicircularis, 533 
 Tarsal cartilages, 69 
 
 ligaments, 69 
 
 Temporal region, dissection of, 82 
 Tegmentum, 554 
 Tendo Achillis, 487 
 Tendo oculi, 67 
 Tentorium cerebelli, 6 
 Testicle, coverings of, 581 
 
 descent of, 585 
 
 structure of, 583 
 Thalamus opticus, 537 
 Thebesii valvula, 135 
 
 foramina, 135 
 Thigh, dissection of, 438 
 
 back of, dissection of, 482 
 Thoracic duct, 122 
 Thyroid body, 29 
 
 cartilage, 163 
 Tongue, dissection of, 172 
 Tonsils, 159 
 Torcular Herophili, 10 
 Trachea, 145 
 
 Tracheotomy, observations on, 34 
 Transverse meso- colon, 334 
 TRIANGLES 
 
 of neck, 21 
 
 anterior, 21 
 posterior, 21 
 
 digastric 35 
 
 of elbow, 246 
 perineum, 362 
 scarpa, 452 
 
 Submaxillary, 35 
 
 supra-clavicular, 22 
 Triangular ligament of urethra, 369 
 Triciispid valve, 136 
 Trigone of bladder, 395 
 Tube, Eustachian, 154 
 
 Fallopian, 409, 418 
 Tuber annulare, or Pons Varolii, 520 
 
 cinereum, 523 
 
 Tubercula quadrigemina, 539 
 Tunica Kuyschiana, 560 
 
 albuginea testis, 582 
 
 vaginalis scroti, 582 
 
 vasculosa scroti, 583 
 Tympanic arteries, 574 
 
 bones, 573 
 Tympanum of the ear. 571 
 
 membrane of, 572 
 
 muscles of. 574 
 
INDEX. 
 
 603 
 
 UMB 
 
 Umbilical artery, remains of. 325 
 Upper arm, dissection of, 232 
 Urachus, 325 
 Ureter, course of, 384 
 
 muscles of, 395 
 
 ligaments of, 409 
 Urethra, male, 385, 399 
 
 membranous part of, 386 
 Urethra, female, 406, 412 
 Uterus, appendages of, 411 
 
 arteries of, 413 
 
 absorbents of, 414 
 
 cervix "of, 415 
 
 description of, 413 
 
 ligaments of, 409 
 
 nerves of, 414 
 
 muscular fibres of, 417 
 
 position of, 409 
 Utriculus, 397 
 Uvea, 563 
 Uvula of bladder, 395 
 
 of palate, 157 
 
 of cerebellum, 542 
 
 Vagina, 407, 412 
 
 bulb of, 407 
 
 sphincter of, 407 
 
 structure of, 415 
 Vaginalis tunica scroti, 582 
 Valsalva, sinuses of, 139 
 VALVES 
 
 of coronary vein, 140 
 
 Eustachian, 135 
 
 ilio-csecal, 437 
 
 mitral, 139 
 
 pulmonary, 137 
 
 semi-lunar, of aorta, 137 
 
 of Thebesius, 135 
 
 of Tarini, 542 
 
 tricuspid, 136 
 
 of Vieussens, 540 
 Valvulse conniventes, 434 
 Vas deferens, 384, 584 
 Vasa efferentia testis, 584 
 
 recta testis, 583 
 VEINS 
 
 anterior jugular, 1 5 
 
 auditory, 578 
 
 axillary, 230 
 
 azygos, 121 
 
 minor, 122 
 
 basilic, 234 
 
 brachial, 239, 241 
 
 VEI 
 
 VEINS (continued) 
 
 brachio-cephalic, left, 106 
 
 right, 106 
 bronchial, 150 
 capsular, 351 
 cava, inferior, 353 
 superior, 107 
 cephalic, 221 
 choroid of eye, 560 
 coronary, 135, 140 
 common iliac, 353 
 dorsalis penis, 380, 404 
 external jugular, 14 
 
 saphena, 485 
 facial, 38, 77 
 femoral, 459 
 of G-alen, 536 
 hfemorrhoidal, 382 
 inferior mesenteric, 343 
 iliac, common, 353 
 external, 353 
 internal, 353 
 
 innominate or brachio-cephalic, 106 
 intercostal, 128 
 internal jugular, 28 
 
 maxillary, 90 
 jugular, anterior, 15 
 
 external, 14 
 
 internal, 28 
 jugulo-cephalic, 221 
 lingual, 45 
 lumbar, 353 
 mammary, internal, 90 
 maxillary, external, 38, 77 
 median, 233 
 
 basilic, 233 
 
 cephalic, 233 
 
 profunda, 233 
 nasal, 199 
 occipital, 48 
 ophthalmic, 185 
 ovarian, 421 
 
 pampiniform, plexus of, 581 
 pharyngeal, plexus of, 153 
 phrenic, 351 
 popliteal, 489 
 portse, 339 
 
 posterior scapular, 59 
 profunda femoris, 461 
 prostatic plexus of, 379 
 radial, 245 
 renal, 352 
 sacra media, 353 
 saphena, 441 
 
604 
 
 INDEX. 
 
 VEI 
 VEINS (continued) 
 
 saphena, external, 485 
 posterior, 485 
 spermatic, 352 
 spinal system of, 544 
 subclavian, 61 
 superior intercostal, 128 
 mesenteric, 342 
 supra- scapular, 59 
 thyroid, middle, 59 
 inferior, 31 
 superior, 47 
 tibial, anterior, 470 
 posterior, 492 
 ulnar, anterior. 245 
 posterior, 245 
 uterine, 414 
 vaginal plexus, 411 
 vena cava, inferior, 353 
 superior, 107 
 vertebral, 58 
 
 vesical plexus of, 379, 396 
 vorticosse oculi, 560 
 Velum interpositum, 536 
 Veneris, mons, 405 
 
 ZlN 
 
 VENTHICLES 
 
 lateral, of brain, 531 
 
 fifth, 534 
 
 third, 537 
 
 fourth, 540 
 
 of the larynx, 1 66 
 
 heart, left, 139 
 
 right, 135 
 Vermiform processes of cerebellum, 542 
 
 superior, 542 
 
 inferior, 542 
 
 Vermiformis, appendix, 327 
 Veru montanum, 397 
 Vesicles, Graafian, 420 
 Vesiculae seminales, 384, 398 
 Vestibule of the ear, 575 
 Villus, structure of a, 434 
 Vocal chords, 167 
 
 Wharton's duct. 37 
 Willis, circle of, 315 
 Winslow, foramen of, 323 
 Wrisberg, nerve of, 233 
 
 Zinn, zone of, 568 
 
 a 0. 
 
 
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