MEDICAL >CH<S>(DL 
 
 -DR. SJ.S. ROGERS 
 
MANUAL 
 
 DISSECTION OF THE HUMAN BODY 
 
HOLDEN'S MANUAL 
 
 EDITED BY 
 
 LUTHER (HOLDEN 
 
 PRESIDENT OK THE ROYAL COLLEGE OP SURGEONS OF ENGLAND : MEMBER OF THE COUUT OF EXAMINERS 
 SENIOR SURGEON TO ST BARTHOLOMEW'S AND THZ FOUNDLING HOSPITALS 
 
 . JOHN LANGKTON, F.K.C.S. 
 
 ASSISTANT-SURGEON AND LECTURER ON ANATOMY AT ST BARTHOLOMEW'S HOSPITAf. 
 
 ILLUSTRATED WITH NUMEROUS WOOD ENGRA VINOS 
 
 FOURTH EDITION 
 
H 
 
 TO 
 
 THE STUDENTS 
 
 OF 
 
 ST BARTHOLOMEW'S HOSPITAL 
 
 IN THE HOPK THAT IT MAY ASSIST THEM 'IN THEI1J 
 ANATOMICAL STUDIES 
 
 $fns Usfmtual is iptbualtfr 
 
 BT THKIU FAITHFUL VHIENI) AND \VEI.L-WISHER 
 
 THE AUTHOR 
 
 47<i 
 
PEE FACE 
 
 TO 
 
 THE FOURTH EDITION. 
 
 IN THIS EDITION the Editors have most carefully revised the 
 entire work. The order of dissection has been here and there 
 altered ; and further illustrations and additional matter intro- 
 duced, especially concerning the Anatomy of the Nervous System 
 and the Senses. 
 
 The object 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 diffi- 
 culties. 
 
 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. 
 
 Our best thanks are due to the Demonstrators of Anatomy 
 at St. Bartholomew's Hospital for valuable suggestions. 
 
 65 GOWEK STREET : 
 October 1879. 
 
CONTENTS. 
 
 PAGE 
 
 DISSECTION OF THE SCALP 1 
 
 DISSECTION OP THE NECK . . .. ,~ .--.... . . 17 
 
 COURSE AND RELATIONS OF THE SUBCLAVIAN ARTERIES . --.< . . 60 
 
 DISSECTION OF THE FACE v ... 73 
 
 MUSCLES OF MASTICATION. TEMPORAL AND PTERYGO-MAXILLARY REGIONS 94 
 
 BRANCHES OF THE INTERNAL MAXILLARY ARTERY IN THE THREE STAGES 
 OF ITS COURSE ; .. .... 100 
 
 BRANCHES OF THE INFERIOR MAXILLARY NERVE 104 
 
 DISSECTION OF THE HEART . . . . . . . . . 155 
 
 FCETAL CIRCULATION . . . . . . . . . . . 168 
 
 STRUCTURE OF THE LUNGS . * , , r . -. . .... 169 
 
 DISSECTION OF THE PHARYNX . . _. v . . . . . . 177 
 
 DISSECTION OF THE LARYNX . . . .... . . . . 189 
 
 DISSECTION OF THE TONGUE 201 
 
 DISSECTION OF THE ORBIT . . . 206 
 
 DISSECTION OF THE SUPERIOR MAXILLARY NERVE . . . . . 218 
 
 DISSECTION OF THE EIGHTH PAIR OF NERVES AT THE BASE OF THE 
 SKULL 224 
 
 DISSECTION OF THE NOSE . 228 
 
X CONTENTS. 
 
 PAOK 
 
 DISSECTION OF THE MUSCLES OF THE BACK 234 
 
 LIGAMENTS OF THE SPINE . . . 240 
 
 DISSECTION OF THE UPPER EXTREMITY 255 
 
 DISSECTION OF THE AXILLA . . . . . . . . . 261 
 
 DISSECTION OF THE UPPER ARM . . 271 
 
 DISSECTION OF THE FRONT OF THE FOREARM . . . , * . . . 285 
 
 DISSECTION OF THE PALM OF THE HAND 297 
 
 MUSCLES OF THE BACK CONNECTED WITH THE ARM 310 
 
 DISSECTION OF THE MUSCLES OF THE SHOULDER 317 
 
 DISSECTION OF THE BACK OF THE FOREARM 325 
 
 DISSECTION OF THE LIGAMENTS , 338 
 
 DISSECTION OF THE ABDOMEN . . '"' 353 
 
 DISSECTION OF THE PARTS CONCERNED IN INGUINAL HERNIA . . 364 
 
 PLAN OF THE BRANCHES OF THE CCELIAC Axis 386 
 
 DISSECTION OF THE PELVIC VISCERA . . . . . .411 
 
 DISSECTION OF THE MALE PERINEUM 414 
 
 ANATOMY OF THE SIDE VIEW OF THE PELVIC VISCERA .... 428 
 STRUCTURE OF THE BLADDER, PROSTATE, URETHRA, AND PENIS . . 446 
 
 DISSECTION OF THE FEMALE PERINEUM 459 
 
 DISSECTION OF THE FEMALE PELVIC VISCERA 463 
 
 DISSECTION OF THE ABDOMINAL VISCERA . . . ... . 475 
 
 DISSECTION OF THE LOWER EXTREMITY 496 
 
 ANATOMY OF THE PARTS CONCERNED IN FEMORAL HERNIA . . . 503 
 
 DISSECTION OF THE FRONT OF THE LEG 525 
 
 DISSECTION OF THE GLUTEAL REGION . . .'''". . . . 533 
 
 DISSECTION OF THE BACK OF THE THIGH . . . . . . . 544 
 
 DISSECTION OF THE SOLE OF THE FOOT 557 
 
CONTENTS. xi 
 
 PAGI? 
 
 DISSECTION OF THE LIGAMENTS 564 
 
 DISSECTION OP THE BRAIN 578 
 
 DISSECTION OF THE SPINAL CORD 617 
 
 DISSECTION OF THE EYE ...."..... . 631 
 
 DISSECTION OF THE ORGAN OF HEARING 648 
 
 DISSECTION OF THE MAMMARY GLAND 663 
 
 DISSECTION OF THE SCROTUM AND TESTIS 665 
 
 INDEX . 673 
 
DISSECTION OF THE HUMAN BODY. 
 
 DISSECTION OF THE SCALP. 
 
 AN INCISION should be made from the root of the 
 DISSECTION. 
 
 nose along the mesial line of the vertex to the 
 
 external protuberance of the occipital bone ; another, horizontally 
 round each half of the head, to join at right angles the two ends 
 of the first incision. These incisions must not divide more than 
 the skin, so that the subcutaneous vessels and nerves be not in- 
 jured. It is well to dissect on one side of the head the muscles 
 only, reserving the other side for the dissection of the vessels and 
 nerves. 
 
 STRATA COMPOS- The several strata of tissues covering the skull- 
 ING THE SCALP. cap are 1, the skin ; 2, a thin layer of adipose 
 tissue which 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 aponeurosis of the occipito-frontalis muscle 
 (apoueurosis of the scalp) ; 4, an abundance of loose connective 
 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 with the aponeurosis of the 
 scalp. It forms a bed for the bulbs of the hair and for the rami- 
 fications of the cutaneous arteries. The toughness of this tissue, 
 
 B 
 
2 DISSECTION OP THE SCALP. 
 
 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. 
 
 This cutaneous muscle is closely connected to the 
 
 OCCIPITO-FRON- 
 
 TALIS MUSCLE scalp. It consists of two fleshy portions, one on the 
 
 AND EPICRANIAL occiput, the other on the forehead, connected by a 
 APONEUROSIS. broad aponeurosis. The occipital portion of the 
 
 muscle takes origin from the outer two-thirds of the upper curved 
 line of the occipital bone, and the adjoining part of the mastoid 
 process. The fibres ascend over the back of the head, and terminate 
 in the epicranial aponeurosis. The frontal portion, commencing in 
 an arched form from the epicranial aponeurosis near the coronal 
 suture, descends over the forehead, and terminates partly in the skin 
 of the brow, partly in the orbicularis oculi and corrugator super- 
 cilii and in the internal angular process of the frontal bone. 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 con- 
 nective tissue. This muscle enables us to move the scalp back- 
 wards and forwards. But its chief action is as a muscle of expres- 
 sion. It elevates the brows, and occasions the transverse wrinkles 
 in the expression of surprise. It is supplied by the posterior 
 auricular and temporal branches of the facial nerve. 
 
 MUSCLES OF There are several small muscles to move the 
 
 THE EAR. cartilage of the ear. In man they are thin and 
 
 pale ; but 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 direction of the sound. 
 
 M. ATTOLLENS To indicate the position of this muscle the 
 
 AUBEM. student should draw 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 epicranial aponeurosis, and 
 is inserted into the cranial aspect of the upper part of the concha. 
 
 M. ATTRAHENS This muscle is smaller than the preceding, 
 
 AUREM. and its situation is indicated by the prominence 
 
ARTEKIES OP THE SCALP. 3 
 
 of skin produced by drawing backwards the front part of the helix. 
 It arises from the aponeurosis of the occipito-frontalis, and is in- 
 serted into the front of the helix. 
 
 M. HETRAHENS This muscle is exposed by reflecting the skin 
 
 AUEEM. from the 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 posterior auricular branch of the facial nerve ; 
 the attrahens, by an offset from the temporal branch of the same 
 nerve. 
 
 ARTERIES OF The arteries of the scalp are derived, in front, 
 
 SCALP. from the supra-orbital and frontal arteries, 
 
 branches of the ophthalmic artery which is a branch of the internal 
 carotid ; on the sides, from the temporal ; behind, from the occi- 
 pital and posterior auricular, all branches of the external carotid. 
 
 The Jrontal emerges from the orbit at its inner angle ; it runs up- 
 wards for a short distance and inosculates with the following artery. 
 
 The supra-orbital passes through the supra-orbital notch and dis- 
 tributes branches, some of which ascend towards the top of the head and 
 communicate with the temporal artery. 
 
 The temporal, about an inch and a half above the zygoma, divides into 
 two branches an anterior and a posterior. The anterior runs forwards 
 in a tortuous course and anastomoses with the supra-orbital artery ; the 
 posterior (usually the larger) arches backwards over the ear, and its 
 branches communicate with the corresponding branch of the opposite 
 side and with the occipital and posterior auricular arteries. 
 
 The posterior auricular is a small vessel seen in the cleft between the 
 ear and the mastoid process : it ascends, and divides into two branches : 
 one, which passes backwards and inosculates with the occipital, the other, 
 which runs forwards above the ear and communicates with the temporal 
 artery. 
 
 The occipital may be noticed piercing the trapezius near to the 
 external occipital protuberance ; ascending over the back of the head, it 
 divides into numerous branches which, inosculate with the preceding 
 arteries. 
 
 The veins of the scalp accompany their respective arteries. 
 
 B 2 
 
NEBVES OF THE SCALP. 
 
 NERVES OF THE 
 SCALP. 
 
 The sensory nerves of the scalp are supplied 
 from each of the three divisions, namely the 
 ophthalmic, the superior maxillary and inferior maxillary, of the 
 fifth pair ; also from the second cervical nerve. The nerves to the 
 muscles of the scalp and ear come from the portio dura or seventh 
 pair (fig. 1 ). 
 
 Fia. 1. 
 
 DIAGBAM OF THE NERVES OF THE SCALP. 
 
 1. Supra- trochlear. 
 
 2. Supra-orbital. 
 
 3. Temporal br. of the superior maxillary. 
 
 4. Auriculo-temporal br. of the inferior maxillary. 
 
 5. Facial represented by dotted lines. 
 
 6. Posterior auricular. 
 
 7. Small occipital. 
 
 8. Great occipital. 
 
 The supra-trochlear nerve is derived from the frontal branch of 
 the ophthalmic division of the fifth. It appears at the inner angle 
 of the orbit, and supplies the skin of the forehead, and the upper eyelid. 
 
 The supra-orbital nerve is a continuation of the frontal branch of the 
 fifth. It emerges from the orbit through the notch in 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 subcu- 
 taneous, and terminate in two branches an inner, which ascends, to 
 
NEEVES OF THE SCALP. 5 
 
 supply the structures as high as the parietal bone ; and an outer and 
 larger, which may be traced over the vertex as far as the occipital bone. 
 
 The temporal branch of the superior maxillary nerve pierces the 
 temporal aponeurosis about an inch above the zygoma, and is distributed 
 to the skin of the temple, communicating with the facial nerve and occa- 
 sionally with the following. 
 
 The auriculo-temporal nerve, a branch of the inferior maxillary nerve, 
 after sending a small filament to the upper part of the pinna, divides into 
 two branches which accompany the divisions of the superficial temporal 
 artery ; of these the posterior is the smaller. 
 
 The temporal branches of the facial nerve lie superficial to the tem- 
 poral aponeurosis, and supply the attrahens aurem, the orbicularis 
 oculi, the occpito-frontalis, and the corrugator supercilii. 
 
 The posterior auricular nerve is a branch of the facial, and divides 
 like its accompanying artery behind the pinna of the ear, into a posterior 
 or occipital branch, which supplies the posterior belly of the occipito- 
 frontalis, and into an anterior or auricular branch, which ends in the 
 auricle, the retrahens aurem and the attollens aurem. 
 
 The great occipital nerve is the posterior branch of the second cervical 
 nerve. After piercing the complexus it appears on the occiput with the 
 occipital artery, and divides into wide-spreading branches which supply 
 the skin. It communicates with the posterior auricular, the small occi- 
 pital, and the third cervical nerves. 
 
 The small occipital nerve, a branch of the anterior division of the 
 second cervical (p. 21), runs along the posterior border of the sterno- 
 irastoid and supplies the scalp. 
 
 Occasionally, though rarely, a cutaneous branch of the suboccipital 
 nerve is distributed to the back of the head. 
 
 POINTS OF SUR- Raise the aponeurosis of the scalp, and observe 
 OICAL INTEBEST. the quantity of loose connective tissue which 
 intervenes between it and the pericranium. This tissue never 
 contains fat. There are some points of surgical interest con- 
 cerning it: 1. Its looseness accounts for the extensive effusions 
 of blood which one often sees after injuries of the head. 2. It 
 admits of large flaps of the scalp being detached from the skull- 
 cap ; but these flaps rarely slough, unless severely damaged, 
 because they carry their blood-vessels with them. 3. In phleg- 
 monous erysipelas of the scalp, the connective tissue becomes 
 
6 DUBA MATER. 
 
 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. 
 
 LYMPHATICS OF The lymphatics of the scalp run for the most part 
 THE SCALP. backwards towards the occiput ; a few run towards 
 
 the root of the zygoma, where they enter the lymphatic glands in 
 those situations, respectively. Here, therefore, one finds glandular 
 enlargements when the scalp is diseased. 
 
 To examine the brain and its membranes, the 
 
 DISSECTION. . *i 
 
 skull-cap must be removed about halt 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. 
 
 The meningeal arteries ramify between the skull and the dura 
 mater. We cannot, however, with the brain in situ, trace their 
 course, at present, throughout ; so their consideration must be 
 deferred until the brain has been removed. 
 
 This membrane is so called because it was 
 DUBA MATER. 
 
 thought to give rise to all the other fibrous mem- 
 branes in the body. It is a dense white fibrous membrane, rough 
 on its outer aspect, where it is more or less adherent to the inner 
 surface of the skull, forming its internal periosteum. On its inner 
 surface it is smooth and shining, being lined by the parietal layer 
 of the arachnoid membrane, which most anatomists now describe 
 as constituting a part of the dura mater. In consequence, the 
 term ' subdural space ' is now substituted for the old one ' the 
 cavity of the arachnoid.' The dura mater differs in its adhesion 
 to the subjacent bones : its adhesion is firmest at the sutures, 
 the petrous portion of the temporal bone, the basilar process, the 
 body of the sphenoid, the cribriform plate of the ethmoid bone, 
 
DUKA MATER. 7 
 
 the depressions for the Pacchionian bodies, and at the margin of 
 the foramen magnum. 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, and 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 support of 
 the lobes of the brain, two are vertical, and separate, respectively, 
 the two hemispheres of the cerebrum, and those of the cerebellum ; 
 the third slopes backwards, and supports the posterior lobes of the 
 cerebrum. 
 
 This partition is named, from its resemblance to 
 the blade of a sickle, falx cerebri. It is received 
 into the longitudinal fissure, and separates the two cerebral hemi- 
 spheres. It begins in a point attached to the crista galli, and 
 gradually becomes broader 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 lower margin is concave and 
 free, and runs along the upper aspect of the corpus callosum. 
 From its base or broadest part proceeds the sloping partition 
 
 TENTORIUM named tentorium cerebelli. This forms an arch 
 
 CEREBELLI. f or the support of the posterior lobes of the 
 
 cerebrum, so that they may not press upon the cerebellum beneath. 
 Observe that the tentorium is attached to the transverse ridge of the 
 occipital bone, to the superior border of the petrous portion of the 
 temporal bone, and to the posterior and anterior clinoid processes 
 of the sphenoid. The small median partition which separates the 
 
 FALX CERE- lobes of the cerebellum is called the falx cerebelli. 
 BELLI - It is placed vertically in the same plane with the falx 
 
 cerebri, and its point is downwards towards the foramen magnum. 
 The dura mater is supplied with nerves by the recurrent branch 
 of the fourth nerve, by the fifth and eighth cranial nerves. Fila- 
 ments have likewise been traced into it from the sympathetic 
 system and from the Orasserian ganglion. 
 
8 SINUSES OF THE DUEA MATER. 
 
 SINUSES OF THE It is one of the peculiarities of the cerebral cir- 
 DUBA MATKB, dilation, that the blood is returned through canals 
 
 or sinuses formed by the dura mater. These canals are produced 
 FTG. 2. by a splitting of the dura mater into two 
 
 " layers as shown in fig. 2, where 1 represents 
 a vertical section through the superior longi- 
 tudinal sinus. They are lined by the same 
 smooth membrane as the rest of the venous 
 2/1 system. Since their walls consist of un- 
 
 TO SHOW FORMA- yielding structure, and are always on the 
 TION OF A SINUS. stretch, it is obvious that they are admir- 
 
 ably adapted to resist the pressure of the brain. There are fifteen 
 of these sinuses ; five are pairs, and five are single, as follows : 
 
 The five pairs of sinuses are The five single sinuses are 
 
 The lateral. The superior longitudinal. 
 
 The superior petrosal. The inferior longitudinal. 
 
 The inferior petrosnl. The circular. 
 
 The cavernous. The transverse. 
 
 The occipital. The straight. 
 
 The blood from all these sinuses is eventually discharged 
 through the internal jugular veins. 
 
 SUPERIOR LON- This runs along the upper edge of the falx cere- 
 GITUDINAL SINUS. bri (fig. 3). It begins very small at the crista 
 ' galli, gradually increases in size 
 
 in its course backwards, and op- 
 posite the internal protuberance 
 of the occipital bone divides into 
 the right and left lateral sinuses, 
 the right being generally the larger. 
 Besides numerous veins from the 
 __ cancellous texture of the skull-cap, 
 
 the superior longitudinal sinus re- 
 
 1. superior longitudinal sinus. ceives large veins from each hemi- 
 
 2. Inferior longitudinal sinus. 
 
 3. straight sinus. sphere of the cerebrum. It is 
 
 interesting to observe that these 
 veins run (as a rule) from behind forwards, contrary to the current 
 
SUPERIOE LONGITUDINAL SINUS. 9 
 
 of blood in the sinus, and that they pass through the wall of the 
 sinus very obliquely, like the ureter into the bladder. The probable 
 object of this oblique entrance is to prevent regurgitation 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 chordae Willisii.* 
 Their precise use is not understood. 
 
 GLANDULE In the neighbourhood of the superior longitu- 
 
 PACCHIONT. dinal sinus, we meet with small white elevated 
 
 granulations, sometimes arranged singly, sometimes in clusters, 
 which are received into the depressions on the inner aspect of the 
 skull-cap. They are termed glandulce PacchioniJ and are found 
 in four 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. 4. On the posterior and antero- 
 inferior parts of the posterior lobe of the cerebrum. 
 
 They are due to an increased growth of the villi, which are nor- 
 mally found in the arachnoid membrane, and make their way, 
 through the dura mater or the pia mater, to the different situations 
 in which they are found. The greatest growth takes place from 
 the visceral layer, as may be seen in the dissection of the brain. 
 These bodies are not found at birth, but usually commence their 
 growth about the third year, and are always found at the seventh 
 year, after which they gradually increase as life advances. 
 
 The brain should now be removed, and preserved in spirit for 
 future examination. Its anatomy, with that of its remaining mem- 
 branes, will be described in a subsequent part of this work. 
 
 The other sinuses should now be examined. 
 
 LATEBAL These are the two great sinuses through which 
 
 SINUSES. all the blood from the brain is returned to the 
 
 jugular veins. Their course is well marked in the dry skull. The 
 
 * So called after Willis, who first described them in his work, 'De Cerebri 
 Anatome,' 1664. 
 
 t After the Italian anatomist who first described them, in 1705. 
 
10 SINUSES OF THE DUEA MATER. 
 
 right is usually the larger. Each commences at the internal 
 occipital protuberance, and proceeds at first horizontally outwards, 
 enclosed between the layers of the tentorium, along a groove in 
 the occipital bone and the posterior inferior angle of the parietal ; 
 it then descends along the mastoid portion of the temporal bone, 
 and again indenting the occipital bone, turns forwards to the 
 foramen lacerum posterius, and terminates in the internal jugular 
 vein.* 
 
 INFERIOR LON- This is of small size. It runs in the inferior 
 
 OITUDINAL SINUS. f ree border of the falx cerebri, and terminates in 
 the straight sinus at the anterior margin of the tentorium 
 (fig. 3). 
 
 This may be considered as the continuation of 
 
 STRAIGHT SINUS. ~ 
 
 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 
 vence Galeni (fig. 3), which return the blood from the lateral 
 ventricles of the brain. 
 
 CAYERNOUS This is so called because its interior is inter- 
 
 SINUS. sected by numerous cords. 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 sphenoidal fissure ; and it communicates 
 with the circular sinus which surrounds the pituitary gland 
 
 (fig- 4). 
 
 This surrounds the pituitary body (P in the 
 CIRCULAR SINUS. *\ j - u * *!. 
 
 diagram 4), and communicates on each side with 
 the cavernous sinus. 
 
 PETROSAL These lead from the cavernous to the lateral 
 
 SINUSES. sinuses. There are two on each side. The supe- 
 
 rior runs along the upper border of the pars petrosa, in the attached 
 border of the tentorium cerebelli ; the inferior, the larger of the 
 two, runs along the suture between the pars petrosa and the occi- 
 
 * It has, in some subjects, another outlet, through the foramen raastoideum, or else 
 through the posterior condyloid foramen. 
 
SINUSES OF THE DUEA MATER. 
 
 pital bone, and ends in the lateral sinus just before this termi- 
 nates in the internal jugular vein. 
 
 TRANSVERSE This extends from one inferior petrosal to the 
 
 other, across the basilar process of the occipital 
 
 SINUS. 
 
 bone. 
 
 FIG. 4. 
 
 Third nerve .... 
 Fourth nerve . . . 
 Sixth nerve . . . 
 First branch of the 
 fifth . . 
 
 Superior petrosal sinus 
 Inferior petrosal sinus 
 
 Ophthalmic vein. 
 
 Carotid artery. 
 Cavernous sinus. 
 
 DIAGRAM OF THE VENOUS SINUSES AT THE BASE OF THE SKULL. 
 
 OCCIPITAL 
 
 SINUSES. 
 
 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 junction of the several siimses opposite the spine of the occipital bone is 
 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 
 
12 MENINGEAL AKTEEIES. 
 
 MENINGEAL These arteries ramify between the skull and the 
 
 ARTERIES. dura, mater. Their course may be traced by the 
 
 grooves which they make in the bones. They are termed anterior, 
 middle, and posterior, from the fossae in which they ramify. 
 
 The anterior meningeal are derived from the ethmoidal branches of 
 the ophthalmic artery, and supply the dura mater in the neighbourhood 
 of the ethmoid bone. 
 
 The middle meningeal are three in number : the most important is 
 the arteria meningea media, a branch of the internal maxillary artery. 
 It enters the skull through tbe foramen spinosum, and divides into two 
 principal branches ; one runs in a groove near the anterior border of the 
 parietal bone, the other curves backwards over the temporal bone, and 
 subsequently ramifies on tbe parietal bone. This artery gives off a small 
 branch the petrosal, which enters the hiatus Fallopii and anastomoses 
 with the stylo-mastoid artery in the aqueeductus Fallopii ; and one or 
 more anastomosing branches which enter the orbit through the sphenoidal 
 fissure to communicate with the ophthalmic artery. It is accompanied 
 by two veins which empty themselves into the internal maxillary vein. 
 The arteria meningea parva, which enters the skull through the foramen 
 ovale, and a meningeal branch from the ascending pharyngeal artery, 
 which comes up through the foramen lacerum medium, also supply the 
 dura mater and bones of the middle fossa. 
 
 The posterior meningeal come from the occipital and the vertebral 
 arteries ; these enter the skull through the foramen jugulare and the 
 foramen 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. 
 
 The student should now examine the cranial 
 DISSECTION. -, ,, ? 
 
 nerves as they pass out through the toramina in 
 
 the base of the skull, and then dissect the cavernous sinus. 
 
 EXIT OF THE The cranial nerves proceed in pairs through the 
 
 CRANIAL NERVES. foramina at the base of the skull ; they are named 
 
 occipital, and that of the straight sinus. The term torcular is an incorrect version of 
 the original word <ra-\V (a canal or gutter), employed by Herophilus. 
 
EXIT OP THE CRANIAL NERVES. 13 
 
 first, second, third, fourth, &c., pairs, according to the order of 
 succession from before backwards. 
 
 The first is the olfactory nerve. This cannot be seen, be- 
 cause the olfactory bulb has been removed with the brain. From 
 the bulb proceed about twenty branches, which pass through the 
 foramina in the cribriform plate of the ethmoid bone, and are 
 arranged in three sets inner, middle, and outer. The inner pass 
 to the septum nasi ; the middle to the roof of the nose ; and the 
 outer to the outer wall of the nose as low as the middle turbinated 
 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, traverses the outer wall of the 
 cavernous sinus, and enters the orbit through the sphenoidal fissure. 
 Before passing through the fissure, it divides into two branches, 
 an upper and a lower. 
 
 The fourth (patheticus\ a small nerve, passes through the 
 dura mater a little behind the posterior clinoid process. Like 
 the preceding nerve, it passes through the outer wall of the cavern- 
 ous sinus, and then runs forward through the sphenoidal fissure. 
 Here, it lies above the third nerve, and is finally distributed to 
 the superior oblique muscle. 
 
 The fifth (trifacial 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. It is formed of two 
 parts a larger or sensory root, and a smaller or motor. Upon its 
 larger or sensory root is developed a large ganglion, the Gasserian 
 ganglion. From this ganglion proceed the three primary divi- 
 sions of the nerve the ophthalmic, which passes through the 
 outer wall of the cavernous sinus, and subsequently enters the 
 orbit through the sphenoidal fissure ; * the superior maxillary, 
 
 * While the nerve is in the cavernous sinus it receives filaments of communication 
 from the cavernous plexus, and also sends back a branch to supply the tentorium 
 cerebelli (Arnold). The ophthalmic nerve is frequently very intimately connected 
 with a branch from the fourth nerve. 
 
14 
 
 EXIT OF THE CRANIAL NERVES. 
 
 which passes through the foramen rotundum ; and the inferior 
 maxillary , which passes through the foramen ovale. The smaller 
 root of the fifth lies beneath the ganglion, with which it has no 
 
 Olfactory bulb . . 
 
 Optic nerve . . 
 
 Third nerve . . 
 
 Fourth nerve . . 
 
 Fifth nerve . . 
 
 Sixth nerve . . 
 Seventh nerve 
 
 Ninth nerve . . 
 
 Eighth nerve . . 
 
 FIG. 5. 
 
 DIAGRAM OF THE EXIT OF THE CRANIAL KEBVES. 
 
 communication, and then joins the inferior maxillary division to 
 supply the muscles of mastication with motor power. 
 
CAVERNOUS SINUS. 15 
 
 The sixth (abducens) pierces the dura mater behind the body 
 of the sphenoid bone, which it grooves. It then passes along 
 the inner wall of the cavernous sinus, external to the carotid 
 artery, and enters the orbit through the sphenoidal fissure, to 
 supply the external rectus. It is connected with the cavernous 
 plexus as it passes along the inner wall of the sinus. 
 
 The seventh, consisting of ihe facial and auditory nerves, passes 
 (with the auditory artery) through the meatus auditorius internus, 
 where the two are connected with each other by small offsets. At 
 first the facial nerve lies internal to and above the auditory ; but 
 at the bottom of the auditory meatus, the facial nerve leaves it to 
 traverse a tortuous bony canal, the ' aquseductus Fallopii ; ' the 
 auditory being distributed to the internal ear. 
 
 The eighth, consisting of the glosso-pharyngeal, pneumo- 
 gastric and spinal accessory nerves, passes through the anterior 
 part of the foramen lacerum posterius. These three divisions do 
 not all pass through the same tube of the 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 
 DISSECTIOH. ,, , . , , . ,. ., 
 
 the nerves which course along its walls to the 
 
 orbit namely, the third, the fourth, the ophthalmic division of 
 the fifth and the sixth nerves. 
 
 CAYEKNOUS This sinus (fig. 4) lies by the side of the body 
 
 SINUS. of the sphenoid bone. In front it receives the 
 
 ophthalmic vein, which passes backwards through the sphenoidal 
 fissure ; while posteriorly it divides into the superior and inferior 
 petrosal sinuses, which have been already described ; on the inner 
 side it communicates with the circular sinus, which surrounds the 
 pituitary body (P in the diagram 4). The interior of the sinus 
 is remarkable for the numerous fine bands of tissue which inter- 
 lace in all directions. 
 
 In the outer wall of the cavernous sinus we trace, from above 
 
16 CAVERNOUS SINUS. 
 
 downwards, the third nerve, the fourth, and the ophthalmic divi- 
 sion of the fifth, in their course to the orbit. On its inner wall, 
 are situated the internal carotid artery with the sixth nerve below 
 and to its outer side. These structures are not actually within 
 the sinus so as to be bathed by the blood, for they are separated 
 from it by the lining membrane of the sinus. 
 
 KEIATIVE Posi- These nerves should be traced from the cavernous 
 TIONS OF NEBVES sinus, forwards, so as to see how they alter their 
 IN SPHENOIDAL relative positions before entering the sphenoidal fissure, 
 FISSUEE. a,nd, again, in their passage through it. 
 
 Just before entering the sphenoidal fissure, the fourth nerve (on its 
 way to the orbital surface of the superior oblique) gets above the third, 
 which here divides into an upper and a lower branch (both proceeding 
 to the ocular surface of the muscles they supply) ; lower still, we have 
 the frontal, lacrymal, and nasal divisions of the ophthalmic lowest of 
 all is the sixth nerve on its way to the external rectus. 
 
 In their passage through the sphenoidal fissure, we find that the 
 fourth nerve, the frontal and lacrymal branches of the ophthalmic, lie at 
 the top, on the same level, and in the above order from within outwards : 
 thus they enter the orbit above the muscles. Lower, and in the follow- 
 ing order from above downwards, come the upper division of the third, 
 the nasal branch of the ophthalmic, the lower division of the third, and 
 the sixth ; all of which (with the ophthalmic vein) enter the orbit 
 between the two origins of the rectus externus. 
 
 The dissector will better remember the varying relations of these 
 nerves, when he has learnt their respective destinations. 
 
 CUEVES OF THE After the removal of the cavernous sinus, a 
 CAEOTID AETEET. good view is obtained of the curves, like the 
 letter S, made by the carotid artery on the side of the pituitary 
 fossa. 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 pro- 
 cess and the optic nerve, where it gives off the ophthalmic artery. 
 Within the cavernous sinus, small branches, arterice receptaculi, 
 arise from the carotid and supply the pituitary body, and the 
 walls of the sinus. 
 
 A careful dissection would show a plexus of sympathetic nerves 
 
DISSECTION OF THE NECK. 17 
 
 on the carotid artery, as it lies by the side of the body of the 
 sphenoid. This is the CAROTID PLEXUS. It is connected by numerous 
 filaments with the sixth nerve and the Grasserian ganglion. Those 
 filaments of the sympathetic seen on the artery in the upper 
 part of the cavernous sinus, constitute the CAVERNOUS PLEXUS, 
 which is in communication with the third, the fourth, and the 
 ophthalmic division of the fifth nerves. 
 
 THE DISSECTION OF THE NECK. 
 
 Make a vertical incision through the skin, down 
 the middle of the neck from the symphysis of the 
 lower 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. Keflect 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. 
 
 PIATTSMA The platysma myoides is the thin cutaneous 
 
 MYOIDES. muscle of the neck. It arises from the sub- 
 
 cutaneous tissue over the pectoralis major and deltoid muscles;* 
 thence proceeding obliquely 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, im- 
 mediately 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.f 
 
 * Some anatomists describe it as having a slender origin from the clavicle and the 
 acromion. 
 
 t Some of the uppermost fibres of this part of the platysma take the name of 
 musculus risorius : this will be described among the muscles of the face. 
 
 C 
 
18 EXTERNAL JUGULAR VEIN. 
 
 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 
 
 D I S*> F CTION 
 
 turn it upwards. Beneath it lies the general in- 
 vestment of the neck, called the 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 The external jugular vein is formed within the 
 
 JUGULAR VEIN. substance 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. 6), to its posterior border, nearly as low down as the 
 clavicle, where it passes through the deep cervical fascia and ter- 
 minates 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, and fre- 
 quently is very small. 
 
 * 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 fare, 
 and there is a little one (2)almaris 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 
 ' panniculus camosus' on the sides of herbivorous quadrupeds, which enables them to 
 twitch their skins, and thus rid themselves of insects. In birds, too, these 
 cutaneous muscles are extremely numerous, each feather having appropriate muscles 
 to move it. 
 
ANTEBIOR JUGULAR VEIN. 
 
 19 
 
 Near the angle of the jaw the external jugular vein communi- 
 cates by a large branch with the internal jugular. 
 
 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. 6. 
 
 Cervical branch of 
 facial n. . . . 
 
 Superficial cervical 
 nerve .... 
 
 External jugu- 
 lar v 
 
 Anterior jugu- 
 lar v. ... 
 
 Small occipital n. 
 
 Auriculo-paro- 
 tidean n, 
 
 Nervus acces- 
 soriu?. 
 
 Descending 
 branch of cer- 
 vical plexus. 
 
 DIAGRAM OF THE SUPERFICIAL NEItTES AND TKIXS OF THE NECK. 
 
 ANTERIOB 
 JUGULAR VEIN. 
 
 The anterior jugular vein is situated more in 
 the middle of the neck, and is much smaller than 
 the external 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. 
 
 c 2 
 
20 CUTANEOUS NERVES OF THE NECK. 
 
 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 
 jugular becomes an important supplemental vein, and attains con- 
 siderable size. It is not uncommon to find it a quarter of an inch 
 in diameter, and we Jiave seen it nearly half an inch. These 
 varieties should be remembered in tracheotomy. 
 
 Superficial lymphatic 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. 
 
 CUTANEOUS ^ke cu taneous nerves of the neck are the super- 
 
 NERVES OF THE ficial branches of the cervical plexus : the plexus 
 NECK. 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 from beneath the posterior 
 border of the sterno-mastoid, and take different directions. They 
 are named thus (fig. 6) : 
 
 'Ascending branches. . j Auriculo-parotideaii. 
 
 ( Small occipital. 
 
 Cutaneous branches of . Transverse branch .... Superficial cervical, 
 the cervical plexus. ] /Sternal. 
 
 Descending branches . . . J Clavicular. 
 I lAcrominl. 
 
 The auriculo-parotidean n. comes 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 or facial branch 
 is distributed to the skin over the parotid gland, and the side of the 
 cheek ; the posterior, after ascending a short distance, gives off an auri- 
 cular branch, which ramifies mainly upon the cranial aspect of the 
 cartilage of the ear; and a smaller branch, the mastoid, which supplies 
 the skin over the mastoid process. Other filaments of this nerve commu- 
 nicate in the substance of the parotid gland with branches of the facial 
 
CEEVICAL FASCIA. 21 
 
 The small occipital n. 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, and communicates with the great 
 occipital and the posterior auricular nerves. It also sends off a branch, 
 which is distributed to the skin of the temporal region. Beneath the 
 sterno-mastoid this nerve commonly forms a loop, which embraces the 
 nervus accessorius, and sends a branch to it. 
 
 The transverse branch, called the superficial cervical n., 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 cervical branch of the facial nerve ; 
 other filaments descend and supply the skin in front of the neck as low 
 as the sternum. 
 
 The descetiding branches are derived from the third and fourth cervi- 
 cal 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. 
 
 Reviewing 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. 
 
 CEEVICAL Look for this branch beneath the fascia near 
 
 BBANCH OF THE the angle of the jaw (p. 92). It leaves the 
 FACIAL NERVE. parotid gland, 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. 
 
 DEEP CERVICAL Now turn your attention to the membranous 
 FASCIA. investment called the deep cervical fascia, which 
 
 encloses the several structures of the neck. In some subjects the 
 fascia is very thin ; in others, with strong muscles, it is pro- 
 portionally dense and resisting. It is always stronger in par- 
 ticular situations, for the more effective protection of the parts 
 
22 CERVICAL FASCIA. 
 
 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 sheaths for the muscles, vessels, and glands. It isolates 
 them, and keeps them in their proper relative position. A length- 
 ened 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 nuchas and to the spinous and trans- 
 verse processes of the cervical vertebrae. From these attachments 
 it passes forwards over the posterior triangle of the neck to the 
 posterior border of the sterno-mastoid, where it splits into two 
 layers, which invest that muscle and reunite 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, and passes over the parotid gland, 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, containing more or less fat, and one or two small 
 lymphatic 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 pneumogastric nerve, which lie behind 
 this muscle ; it is continued behind the pharynx (constituting 
 the pr<xvertebral fascia} to join the fascia of the opposite side. 
 
CEEVICAL FASCIA. 23 
 
 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 in the chest with the pericardium. It 
 may, also, be traced under the clavicle 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 travel through the loose tissue by the side of 
 the pharynx, and make its way into the chest, where it may 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 
 destruction 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 
 
 * ' Surgical A natomy of the Head and Neck.' 
 
24 STERNO-CLEIDO-MASTOIDEUS. 
 
 when divided they gape. They are, as the French express it, 
 * canaliseesj 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 
 great veins makes them more liable to the entrance of air when 
 wounded. Instances of death have been recorded, resulting from 
 the sudden entrance of air into the veins during operations about 
 the neck, or even the axilla. 
 
 STERNOCLEIDO- The sterno-cleido-mastoideus arises by a rounded 
 MA.STOIDEUS. tendon from the upper part of the sternum, and 
 
 by fleshy fibres, from the sternal third of the clavicle. It is 
 inserted by a thick tendon into the mastoid process, and by a 
 thin aponeurosis into 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 OF When both sterno-mastoids act simultaneously 
 
 STERKO-MASTOID. they draw the head and neck forwards, and are 
 therefore 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 splenius 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 by three nutrient arteries an 
 
 * 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, Itst, 
 after having divided the sterno-mastoid, we should be disappointed in removing the 
 deformity. 
 
TRIANGLES OF THE NECK. 25 
 
 upper, a middle, and a lower. The upper sterno-mastoid artery, a 
 branch of the occipital, enters the muscle with the n. accessorius, 
 close to the mastoid process of the temporal bone ; the middle 
 mastoid is a branch of the superior thyroid, and enters the under 
 surface of the muscle, crossing over the common carotid on a 
 level with the thyroid cartilage ; the lower mastoid is a branch 
 of the supra-scapular, and supplies the clavicular portion of the 
 muscle, close to its origin. 
 
 The sterno-mastoid is supplied with nerves by the n. acces- 
 sorius, and by branches from the deep cervical plexus ; these 
 branches come from the second and sometimes the third cervical 
 nerves. 
 
 TRIANGLES OF Anatomists avail themselves of the oblique 
 
 THE NECK. direction of the sterno-mastoid muscle to divide 
 
 the neck on each side into two great triangles, an anterior and a 
 posterior (fig. 7). 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 posterior has the clavicle for the base, while 
 the sides are defined by the hind border of the sterno-mastoid, and 
 the front border of the trapezius. 
 
 The omo-hyoid muscle, which crosses the neck under the 
 sterno-mastoid, subdivides these primary triangles into four smaller 
 ones (fig. 7), of unequal size : an anterior superior, an anterior 
 inferior, a posterior superior, and a posterior inferior. The 
 direction of the omo-hyoid muscle renders their boundaries at once 
 obvious. 
 
 CONTENTS OF The fat and connective tissue must now be care- 
 
 POSTERIOR fully removed from the posterior triangle. The 
 
 TRIANGLE. following muscles will be seen forming its floor, 
 
 viz., beginning from above, the splenius capitis, the levator anguli 
 scapulae, the scalenus medius and posticus, and a small portion of 
 the serratus magnus. This triangle is subdivided into two unequal 
 parts by the posterior belly of the omo-hyoid an upper or occi- 
 pital and a lower or clavicular. In the occipital triangle, besides 
 the muscles just mentioned (with the exception of the serratus 
 magnus), are found the superficial branches of the cervical plexus, 
 
26 
 
 NEEVUS ACCESSOKIUS* 
 
 and, passing obliquely downwards from beneath the stern o-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 
 posterior border of the sterno-mastoid. 
 
 . 7. 
 
 N. acccssorius . . 
 
 Digastricus . . . 
 
 Os hyoides . . . 
 
 Omo-hyoideus . . 
 
 Sterno-mastoid 
 muscle drawn a side. 
 
 Splenius capitis. 
 
 Levator anguli sca- 
 pulse. 
 
 Scalenus medius. 
 
 Scalenus auticus. 
 
 DIAGRAM OF TBI ANGLES OF THE NECK. 
 
 The upper part of the sterno-mastoid is traversed 
 ACCESSOEIUS. obliquely by a large nerve called the spinal acces- 
 
 sory or n. accessorius. This nerve, one of the three composing 
 the eighth pair of cerebral nerves, arises from the side of the 
 medulla oblongata below the pneumogastric nerve, and from the 
 cervical portion of the spinal cord by a series of filaments from the 
 lateral tract as low down as the sixth cervical vertebra. It ascends 
 between the ligamentum denticulatum and the posterior roots of 
 the spinal nerves, through the foramen magnum into the skull. 
 
SUPRA-CLAVICULAR TRIANGLE. 27 
 
 It consists of two portions, a medullary and a spinal, and leaves 
 the skull through the foramen jugulare. Here the medullary 
 or accessory portion is connected with the ganglion of the root 
 of the pneumogastric by several filaments ; and lower down it 
 again joins the pneumogastric at the ganglion of the trunk, 
 below which the two nerves become blended. The medullary and 
 spinal portions communicate in the foramen jugulare. Below the 
 foramen the spinal part runs behind the internal jugular vein, 
 then pierces obliquely the upper third of the sterno-mastoid, and 
 crosses the posterior triangle of the neck to the under surface of 
 the trapezius, to which it is distributed. The nervus accessorius 
 supplies also the sterno-mastoid, and, after leaving the muscle, is 
 joined by branches from the second and third cervical nerves. 
 Beneath the trapezius it forms a plexus with the third and fourth 
 cervical nerves. The upper mastoid artery, a branch of the occi- 
 pital, enters the sterno-mastoid with the nerve. 
 
 SUPHA-CIAVICU- The supra-clavicular triangle is bounded below 
 LAB TBIANGLE. by the clavicle, in front by the outer border of 
 the sterno-mastoid. 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 and trapezius are attached to 
 the clavicle. 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 lymphatic glands continuous with those in the axilla. It will 
 be easily understood how a collection of pus, originating in the 
 axilla, may ascend in front of the vessels and point above the 
 
28 ANTERIOR TRIANGLE. 
 
 clavicle, or, vice versa, how 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 there is in this situation a confluence of veins, 
 which, when large or distended, are exceedingly embarrassing. 
 
 The fascia and the glands should be removed, 
 DISSECTION" 
 
 and the following 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 transversalis colli, or posterior scapular (com- 
 monly 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 descends from the transverse processes of the 
 cervical vertebrae to the first rib : running down longitudinally 
 upon it is seen the phrenic nerve. The subclavian vein lies upon 
 the first rib in front of the insertion of the anterior scalene muscle. 
 The subclavian artery, which appears a little higher than the vein 
 behind the outer border of the scalenus anticus, must be fairly 
 exposed, care being taken to preserve the small branch which pro- 
 ceeds 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 subcla- 
 vian artery, and on a plane posterior to that vessel. 
 
 DISSECTION The anterior triangle must now be dissected. 
 
 OF THE ANTERIOR In doing so, notice, before the deep cervical fascia 
 TRIANGLE. j g removec i ? the arching forwards of the anterior 
 
 border of the sterno-mastoid muscle, which is connected to the 
 lower jaw by the fascia, so that the common carotid artery is con- 
 cealed from view before the parts are disturbed. Then examine the 
 flat muscles in front of the neck, which pull down the larynx and 
 
DEPRESSORS OP THE OS HTOIDES. 29 
 
 os hyoides ; namely, the sterno-hyoid, sterno-thyroid, omo-hyoid, and 
 thyro-hyoid.* Kemove 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 
 STERNO-HYOID. ., , . , . , .. 
 
 the sternum and posterior sterno-ciavicular liga- 
 ment, and occasionally from the clavicle and cartilage of the first 
 rib, 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 
 laryngotomy. 
 
 ST.KRNO- The sterno-thyroid arises from the back part of 
 
 THTEOID. the sternum, below and internal to 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. 
 
 The two sterno-hyoid muscles converge as they ascend to their 
 insertions, and 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, but are in 
 contact below, the result of which is that the trachea is completely 
 covered in front by muscular fibres. 
 
 The omo-hyoid arises from the upper border 
 
 of the scapula, and from the ligament over the 
 notch, and is inserted into the lower border of the body of the 
 os hyoides near the great cornu. This muscle consists of two 
 fleshy portions connected by a tendon. From the scapula it 
 comes nearly horizontally 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. 
 
 * The sterno-hyoid and sterno-thyroid muscles often present slight transverse 
 tendinous lines. These tendinous intersections are quite rudimentary in man ; but in 
 eome animals with long necks, e.g. the giraffe, they are so developed that each de- 
 pressor muscle is composed of alternations of muscle and tendon. 
 
DEPEESSOES OF THE OS HYOIDES. 
 
 Thus the muscle does not proceed straight from origin to insertion, 
 but forms an obtuse angle beneath the sterno-mastoid muscle. 
 The intermediate tendon is situated at the angle, and is bound 
 
 Occipital a. . 
 
 Hyroglossal n. 
 Descendens 
 noni n. . . 
 
 2nd cervical n. 
 
 Superior thy- 
 roid a. . 
 
 3rd cervical n. . 
 Communicans 
 noni n. . . . 
 
 Crico- thyroid m. 
 
 Internal jugu- 
 lar v. ." . . 
 
 Common caro- 
 tid a. . . . 
 
 Digastricus. 
 
 Junction of my- 
 lo-hyoidei. 
 
 N. accessorius. 
 
 Pomum Adami. 
 
 Cricoid cartilage. 
 
 Isthmus of thy- 
 roid gland. 
 
 Trachea. 
 
 Middle thy- 
 roid v. 
 
 CENTRAL LIVE OF NECK. COURSE AND RELATIONS OF COMMON CAROTID ARTERY. 
 
 down to the first rib and the sternum 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 
 
DEPRESSORS OP THE OS HYOIDES. 31 
 
 which covers the apex of the lung, and thus to resist atmospheric 
 pressure. 
 
 ACTION OF THE The sterno-hyoid, sterno-thyroid, and omo- 
 
 DEPRESSOR hyoid muscles, co-operate in fixing the larynx and 
 
 MUSCLES. os hyoides, e. g. in sucking, or they depress the 
 
 larynx after it has been raised in deglutition. Again, they depress 
 it in the utterance of low notes. That the larynx is raised or 
 depressed according to the height of the note may be ascertained 
 by placing the ringer upon it while singing through an octave. 
 
 These depressor muscles are all supplied with nerves (fig. 8, 
 p. 30) by the descendens noni (a branch of the ninth or hypo- 
 glossal), and by the communicantes noni (branches of the second 
 and third cervical nerves). The descendens noni sends a separate 
 branch to each belly of the omo-hyoid. They are supplied with 
 blood by the superior and inferior thyroid arteries. 
 
 The thyro-hyoid arises from the oblique line 
 THYRO-HYOID. * J 
 
 on the ala of the 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 stern o-mastoid muscle must now be cut 
 DISSECTION. 
 
 transversely through the middle, and the two ends 
 
 turned upwards and downwards, so that they may be replaced if 
 necessary. This done, notice the strong layer of fascia which lies 
 under the muscle and forms part of its sheath. It is attached to 
 the angle of the jaw, thence descends over the large vessels of the 
 neck, and is firmly connected to the clavicle and first rib. This 
 fascia prevents matter coming 'to the surface, when suppuration 
 takes place by the side of the pharynx. 
 
 Remove the fascia, and clean the various structures beneath 
 the sterno-mastoid, taking care not to cut away the descendens 
 noni and communicantes noni nerves, which cross the sheath of 
 the common carotid. Dissect out the lymphatic glands which lie 
 along the sheath of the large vessels. 
 
32 COMMON CAROTID ARTERY. 
 
 PAETS EXPOSED The objects exposed to view, when the muscle is 
 BENEATH THE reflected, are very numerous. Among these the more 
 
 STEBKO-MASTOID. i mport ant are : the splenius capitis and colli, the 
 posterior belly of the digastricus, the levator anguli scapulae, sca- 
 lenus medius and anticus, omo-hyoid, sterno-hyoid, and sterno- 
 thyroid muscles ; the occipital artery, the common carotid artery 
 and its division, the internal jugular vein, the subclavian artery 
 and the branches of the first part of its course, the cervical plexus, 
 and the lower cervical nerves which form the brachial plexus; 
 the phrenic, pneumogastric, hypoglossal, and spinal accessory 
 nerves, the descendens and communicantes noni nerves ; the sub- 
 clavian vein and its tributaries ; and lastly, a small part of the 
 parotid gland, and the three sterno-mastoid arteries. On the 
 left side, in addition, we find the thoracic duct. 
 
 COURSE AND The common carotid arises on the right side 
 
 EELATIONS OF THE from the arteria innominata behind the upper 
 COMMON CAROTID. p ar ^ o f ft\e right sterno-clavicular articulation ; 
 on the left, from the arch of the aorta. It ascends in front of the 
 bodies of the cervical vertebrae, 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 the deep 
 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 are the sympathetic 
 nerve, the inferior thyroid artery, and the recurrent laryngeal nerve. 
 Lastly, along the vertebral column the sheath lies successively 
 upon the longus colli and the rectus capitis anticus major muscles. 
 Owing to the increasing breadth of the larynx, the two common 
 carotid arteries, which at their origin lie near together, are 
 separated by a wide interval at their point of division. 
 
 At the lower part of the neck the carotid artery is deeply 
 seated ; it is covered by the superficial fascia, platysma myoides, 
 
COMMON CAEOTID AETEEY. 33 
 
 deep fascia, the sternal portion of the sterno-mastoid, the sterno- 
 hyoid, and thyroid muscles, and, on a level with the cricoid carti- 
 lage, it is crossed by the omo-hyoid. Above this point the artery 
 becomes more superficial, and is covered by the platysma, the cer- 
 vical fascia, the middle sterno-mastoid artery, and only slightly 
 overlapped by the sterno-mastoid. Lying vipon 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 inferior* thyroid veins, which empty them- 
 selves 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. To the inner side of the artery we find the trachea, the 
 thyroid body, the recurrent laryngeal nerve, the inferior thyroid 
 artery, the external laryngeal nerve, and the inferior constrictor 
 of the pharynx. 
 
 It is evidently easier to tie the common carotid above the 
 omo-hyoid than below it. In the higher operation we make an 
 incision (two and a half inches long) along the inner border of the 
 sterno-mastoid, the centre of the incision being opposite the cricoid 
 cartilage ; we cut through the platysma and cervical fascia, draw 
 aside the overlapping edge of the sterno-mastoid, and expose the 
 sheath of the vessel. A small opening is then made on the inner 
 side of the sheath large enough to admit the aneurysmal needle, 
 and the vessel is tied, care being taken not to include the pneumo- 
 gastric or descendens noni nerves in the ligature. 
 
 In the first part of its course the left carotid 
 
 J.N WHAT HE- * 
 
 SPBCTS THE LEFT differs from the right in the following parti- 
 
 CAKOTID DIFFERS culars : 
 
 FEOM THE EIGHT. lt j t arigeg from the ar(jh of the aorta? ig there . 
 
 fore 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. 
 
 * The term 'inferior thyroid' vein is restricted in this manual to the vein which 
 corresponds to the inferior thyroid artery. 
 
 D 
 
34 INTEBNAL JUGULAR VEIN. 
 
 3. It is in close relation with the oesophagus and the 
 trachea. 
 
 4. It is in close relation with the left recurrent nerve. 
 
 5. It is in close relation posteriorly with the thoracic duct. 
 
 6. It is covered by the thymus gland in early life. 
 
 The common carotid as a rule gives off no branch in its course ; 
 but, occasionally, the middle sterno-mastoid, or even the superior 
 thyroid, arises from it prior to its division. At its bifurcation it 
 usually presents a slight bulbous enlargement. This dilatation is 
 sometimes so marked, that it might be mistaken for an incipient 
 aneurysm. It is necessary to know that the carotid sometimes 
 divides as low as the level of the cricoid cartilage, and that not 
 unfrequently the division takes place as high as the hyoid bone.* 
 
 INTEBNAL The internal jugular vein is the continuation of 
 
 JUGULAR VEIN. the lateral sinus, and returns the blood from the 
 brain. Leaving the skull through the foramen jugulare, where it 
 presents a slight enlargement, the vein descends 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 or in- 
 ' nominate vein. In its course down the neck it receives the 
 pharyngeal, occipital, lingual, facial, superior, and inferior thyroid 
 veins. 
 
 Previous to their terminations the internal jugular veins incline 
 somewhat to the right side to meet the corresponding subclavian 
 veins ; thus, on the right side, there is a triangular interval 
 between the artery and vein in which is seen the pneumogastric 
 nerve and vertebral artery ; on the left side the vein slightly 
 overlaps the artery, thus rendering ligature of the left carotid 
 more difficult than of the right. The internal jugular veins more- 
 
 * It is important that we should be aware that the common carotids differ occa- 
 sionally in their origin. Thus the right may arise in common with the left carotid, 
 or the right may arise separately from the arch of the aorta, in which case the right 
 subclayian is usually transposed. The left may be given off from the innominate 
 artery of the right side, or it may arise in common with the left (-ubclavian, and thus 
 form a left innominate. In transposition of the aorta there is a left innominate, 
 which is given off first, the right carotid and the right subclavian arising as separate 
 branches from the arch. 
 
DESCENDINS NONI NERVE. 35 
 
 over advance slightly to meet the subclavian veins, so that they lie 
 on a plane a little anterior to their accompanying arteries. A 
 little before their termination the internal jugulars have a double 
 valve. 
 
 DESCENDENS The descendens noni (p. 30), a branch of the 
 
 NONI AND COM- hypoglossal, runs down obliquely over the sheath 
 MUNICANTES NONI o f foe carotid to supply the depressor muscles of 
 the os hyoides. Trace the nerve upwards to see 
 that it leaves the hypoglossal where this nerve curves round the 
 occipital 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 over 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 com- 
 municating branches descend on the outer side of the internal 
 jugular vein, and form generally two loops in front of the carotid 
 sheath, constituting a triangular plexus called the ' ansa hypo- 
 glossi.' From these loops the nerves proceed to the anterior and 
 posterior bellies of the omo-hyoid, to the sterno-hyoid. and sterno- 
 thyroid muscles. A small branch may sometimes be traced pro- 
 ceeding from the descendens noni into the chest to join the cardiac 
 and phrenic nerves. 
 
 In some subjects the descendens noni seems to be wanting, 
 in which case it will probably be concealed within, the carotid 
 sheath : when this happens the reinforcing loops from the cervical 
 nerves will be found behind the internal jugular vein.* 
 
 The thyroid body should now be examined. 
 DISSECTION. * * 
 
 To expose it, reflect the sterno-hyoid and thyroid 
 muscles from their insertions, so that they can be replaced if 
 necessary. Next observe the lymphatic glands of the neck, and 
 
 * By many anatomists the descendens noni is regarded as the combination of 
 filaments from the hypoglossal and pneumogastric nerves; by some, it is looked upon 
 as a branch of the pneumogasfric; and lastly, which is most probable, it is considered 
 by others to be mainly derived from a branch which is sent to the hypoglossal from 
 the first and second cervical nerves. 
 
 D 2 
 
36 THYROID BODY. 
 
 lastly survey the objects in the central line of the neck, from 
 the jaw to the sternum. 
 
 This very vascular gland-like body lies over the 
 front and sides of the upper part of the trachea, 
 and extends upwards on each side of the larynx. It consists of 
 two lateral lobes, connected a little below the cricoid cartilage by 
 a tranverse portion called the isthmus. Each lobe is conical, 
 about two inches in length, with the base opposite the fifth or 
 sixth ring of the trachea, and the apex by the side of the thy- 
 roid cartilage. Its anterior surface is covered by the sterno-hyoid, 
 sterno-thyroid, and omo-hyoid muscles ; its deep surface embraces 
 the sides of the trachea and larynx, and usually extends so far back- 
 wards 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.* Grenerally, the vertical measure- 
 ment is about half an inch. Between its upper border and the 
 cricoid cartilage is a space about one-third of an inch 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, so that it has 
 been seen covering the trachea almost down to the sternum.f 
 
 * Concerning the development of the lateral halves and central portion of the 
 thyroid body, see a paper by Callender in the Proceedings of the Royal 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 attached 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 glandula thyroidece (see preparation in 
 Museum of St. Earth. Hosp., Patholog. Series, No. 14) of some anatomists. There 
 
THYROID BODY. 37 
 
 The thyroid body is closely connected, by areolar tissue, to the 
 sides of the trachea, to the cricoid and thyroid cartilages. Hence 
 it rises and falls with the larynx in deglutition. 
 
 The thyroid varies in size in different individuals and at differ- 
 ent periods of life. It is relatively larger in the child than the 
 adult, in the female than the male. In old age it diminishes in 
 size, becomes firmer, and occasionally contains earthy matter. 
 
 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. 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 (thyroidea ima), is observed in some subjects ; it is given 
 off 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 inferior thyroid veins cross the common carotid, and 
 open into the internal jugular. The middle 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 middle 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. 
 
 STRUCTURE OF The thyroid body weighs from one to two ounces, 
 
 THE THYROID and belongs to the class of ductless glands, since 
 
 BODT - no excretory duct has been discovered. It is 
 
 invested by a thin covering of dense connective tissue which 
 
 are instances in which the pyramid is double; and, lastly, we 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 rest, and occasion a 
 bronchocele. 
 
38 DEEP CERVICAL LYMPHATIC GLANDS. 
 
 penetrates 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, from -g^- inch to that of a pin's head, and do 
 not communicate with each other. In hypertrophy of the gland 
 we sometimes see them as large as a horsebean, or even larger. 
 The cells are oval and are lined by a single layer of endothelial 
 cells resting upon a basement membrane, and contain a glairy 
 transparent fluid, in which are found a large number of nuclei and 
 nucleated cells. The arteries ramify most minutely upon their 
 walls. Of its functions nothing is definitely known, but probably 
 it is concerned in the elaboration '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 Allan 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 lymphatic 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. 
 
 DEEP CERVICAL I n the connective tissue which surrounds the 
 LYMPHATIC great vessels of the neck, we meet with a series 
 
 GLANDS. o f lymphatic glands, called the deep cervical. 
 
 * The thyroid body is, primarily, developed as a pouch from the anterior wall of 
 the pharynx; the lateral lobes are first formed, and are subsequently united by the 
 isthmus. W. Muller, ' Jenaisch. Zeitsch.' 1871. 
 
OENTEAL LINE OP THE NECK. 39 
 
 They form an uninterrupted chain (whence their name glandules 
 concatenate), 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 
 belly of the digastricus. The lymphatics 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 aneurysm. A 
 careful examination, however, will distinguish between an inher- 
 ent 'and a communicated pulsation. By grasping the tumour we 
 become sensible that the pulsation does not depend upon any 
 variation 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. 
 
 SURVEY OF THE The parts in the central line of the neck should 
 CENTRAL LINE OF now be well studied (fig. 8, p. 30). Beginning 
 THE NECK. a j. {.j,j e c hi n) we observe the insertions of the 
 
 digastric muscles. Below these is the junction, or raphe, of the 
 mylo-hyoid muscles. Then comes the os hyoides. Below the 
 os hyoides is the thyro-hyoid membrane, attached above to the 
 upper border of the hyoid bone, and below to the thyroid cartilage. 
 Next is the pomum Adami, or projection of the thyroid cartilage, 
 which is apparent between the contiguous borders of the sterno- 
 hyoidei. Below the thyroid cartilage is the cricoid. These two 
 
40 CENTRAL LINE OF THE NECK. 
 
 cartilages are connected by the crico-thyroid membrane, across 
 which runs the crico-thyroid artery to join its fellow. Below the 
 cricoid cartilage is the trachea. This is crossed by the isthmus 
 of the thyroid body, and lower down it recedes from the surface, 
 covered by the middle thyroid veins. 
 
 Now the chief surgical interest lies just above, and just below, 
 the cricoid cartilage. This cartilage can be felt 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 
 membrane. If more room be required, the cricoid cartilage should 
 be divided longitudinally. 
 
 In tracheotomy, the trachea may be opened by a perpendicular 
 incision, 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 tube, 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 middle 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 : 
 
SUBMAXILLARY EEGION. 41 
 
 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. 
 
 Whoever pays attention to this subject in the dissecting-room 
 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, thus showing the necessity of cutting cautiously 
 down to, and fairly exposing the air tube, before we venture to 
 open it.* 
 
 DISSECTION OF "When the platysma and the cervical fascia have 
 
 THE StrBMAxiL- ^^ remove( j f rom fo^y. attachment to the jaw, 
 LAKY KEQION, OR . . i i 
 
 THE DIGASTRIC the mos t conspicuous object is the submaxillary 
 
 TRIANGLE. gland. Observe that the fascia forms for it a 
 
 complete capsule. Beneath the jaw are several lymphatic glands, 
 from six to ten in number, of which some lie superficial to the 
 salivary gland, others beneath it. These glands receive the 
 lymphatics of the face, the tonsils, and the tongue. 
 
 A little dissection will expose a muscle called the 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, passes obliquely down- 
 wards and forwards, and then ascends to be 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 
 
 * It is preferable, after making the first incision through the skin, to lay aside the 
 sharp knife and to use a blunt one, so that the tissues may be torn rather than cut ; 
 by this proceeding the liability to hsemorrhage is materially lessened. 
 
42 
 
 SUBMAXILLART EEGION. 
 
 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. 
 
 FIG. 9. 
 
 Occipital a. 
 
 Facial a. 
 Mylo-hyoid n. 
 
 Snbmental a. 
 
 Descendens noni n. . . 
 Lingual a 
 
 Internal jugular v. . . 
 Superior thyroid a. . . 
 
 Common carotid a . 
 
 DIGASTRIC TRIANGLE AND CONTENTS. 
 
 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). 
 
SUBMAXILLARY REGION. 43 
 
 STYLO- The stylo-hyoideus arises from the middle of 
 
 HYOIDEUS. the styloid process of the temporal bone, and is 
 
 inserted into the body of the os hyoides. This muscle runs close 
 along, but above, the posterior belly of the digastricus. Most 
 frequently the digastric tendon runs through the substance of it. 
 Its nerve is derived from the facial close to its exit from the 
 stylo-mastoid foramen, in common with the branch to the posterior 
 belly of the digastricus. Its action is to raise and draw back the 
 os hyoides. 
 
 The digastric triangle is bounded above by the horizontal 
 ramus 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 the anterior belly. The objects to be examined in 
 this triangle are twelve in number, as follow : 
 
 1. Submaxillary salivary 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 lymphatic glands. 12. Part of the hyo-glossus muscle. 
 
 SUBMAXILLARY In the ordinary position of the head, the sub- 
 
 SALIVAEY GLAND, maxillary gland is partially concealed by the jaw, 
 but when the head falls back the gland is more exposed. 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, being covered only by the skin and platysma, 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 
 deeper surface and subsequently upon 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 
 
44 SUBMAXILLARY REGION. 
 
 they are of importance, as will be presently explained, in tying 
 the lingual artery. 
 
 The duct of the gland, W. harton'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 fraenum linguae. Its length is about two inches ; its dimen- 
 sions are not equal throughout ; 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 
 narrow orifice, in consequence of the sudden contraction of the 
 neighbouring muscles. 
 
 In the floor of the mouth there occasionally exists a cystic 
 tumour, called a ranula, with semi-transparent walls, perceptible 
 beneath the tongue. By some of the older writers it was looked 
 upon as an abnormal dilatation of the submaxillary duct. There 
 is, however, no reason for believing this swelling (except very 
 rarely) to be connected with the duct. It is rather a cyst formed 
 in the loose areolar tissue under the tongue, or is an enlargement of 
 one of the small bursse which normally exist in this situation. 
 The character of the saliva presents no agreement with the fluid 
 contained in these cysts, which is thickly glairy, like the white 
 of an egg.f 
 
 The facial vein does not accompany the facial 
 
 FACIAL VEIN. , . . , 
 
 artery, but runs nearly a straight course. It 
 leaves the face at the anterior edge of the masseter m., then runs 
 over the submaxillary gland, the digastricus 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. 
 
 * Thorn. Wharton, ' Adenographia, seu glandularum totius corporis descriptio.' 
 12mo. Amstel., 1659. 
 
 t These sublingual bursse were first described by Fleischmann, 'De novis sub 
 lingua bursis,' Nuremberg, 1841. 
 
SUBMAXILLAET REGION. 45 
 
 The facial artery is the third branch of the 
 external carotid. It runs tortuously under the 
 hypoglossal nerve, the posterior belly of the digastricus and stylo- 
 hyoideus, and beneath 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 m. to the pharynx, to which 
 and the neighbouring parts it gives branches. Ascending as far as 
 the levator palati, it divides into two branches ; one courses along 
 the tensor palati to supply the soft palate, the other enters the tonsil, 
 and anastomoses with the descending palatine and the tonsillar branches 
 of the ascending pharyngeal. 
 
 2. The tonsillar runs up between the internal pteiygoid and the 
 stylo-glossus m., then, perforating the superior constrictor, it supplies the 
 tonsil and root of the tongue. 
 
 3. Glandular branches to the submaxillary gland and side of tongue. 
 
 4. The submental arises from the facial behind the submaxillary 
 gland, and runs forwards upon the mylo-hyoideus, beneath the inferior 
 maxilla, distributing branches in its course to the gland and the adjacent 
 muscles. It then curves over the bone and divides into two branches : 
 a superficial one, which supplies the skin and lip ; and a deep one, which 
 runs between the muscles and the bone, and inosculates with the mental 
 and inferior labial arteries. Beneath the inferior maxilla it usually 
 inosculates with the sublingual artery. 
 
 MYLO-HYOIDEAN Look for the mylo-hyoidean nerve near the 
 NERVE. submental artery. The nerve comes from the 
 
 inferior dental (before its entrance into the dental foramen), 
 and running along a groove on the inner side of the inferior 
 maxilla, advances between the bone and the internal pterygoid 
 m., to supply the mylo-hyoideus and the anterior belly of the 
 digastricus. 
 
 SUBMAXILLARY ^ ne submaxillary lymphatic glands receive the 
 
 LYMPHATIC lymphatics of the face and the tongue. They are 
 
 GLANDS. often enlarged in cancerous diseases of the tongue 
 
46 SUBMAXILLART REGION. 
 
 or the lower lip. It should be remembered also that there are 
 lymphatic glands in the mesial line below the chin. 
 
 MYLO- The mylo-hyoideus arises from the mylo-hyoid 
 
 HTOIDEUS. ridge of the lower jaw, as far back as the last 
 
 molar tooth. Its posterior fibres are inserted into the body of 
 the os hyoides, the anterior being attached to a median tendinous 
 line, termed the 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 inferior dental ; with 
 blood by the submental a. The muscles of opposite sides con- 
 jointly elevate the os hyoides and the floor of the mouth as in 
 deglutition. 
 
 STTLO-MAXIL- This is a layer of the deep cervical fascia, 
 
 LAKY LIGAMENT. extending from the angle of the jaw to the styloid 
 process. It is a broad sheet of fascia, and separates the submaxil- 
 lary 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 surface. 
 
 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 
 to a piece of surgical anatomy, which will enable you readily to 
 find and tie the lingual artery. It is this : 
 
 A curved incision about two inches in length being made from 
 the lesser cornu along the upper border of the great cornu of the 
 os hyoides, through the skin, the platysma, and the cervical fascia, 
 you will come upon the lower edge of the submaxillary gland. 
 Lift up the gland, which is 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 hyo-glossus : under them is 
 the lingual artery, lying on the middle constrictor. The first time 
 you perform this operation on the dead subject, you will not 
 
SUBMAXILLARY REGION. 47 
 
 unlikely miss the artery and cut through the middle constrictor 
 into the pharynx. 
 
 The facial vessels must now be divided imme- 
 diately below the jaw. Keflect the anterior belly 
 of the digastricus from its insertion ; 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 
 one side of the symphysis, and the bone drawn upwards by hooks. 
 The tongue should then 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, by carefully cleaning away the fat and connective tissue, 
 the following objects represented in fig. 10, p. 48 : 
 
 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. 
 
 GBNIO- The genio-hyoideus arises from the inferior 
 
 HTOIDEUS. tubercle behind the symphysis of the jaw, and is 
 
 inserted into the front of the body 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 
 upwards ; and if the hyoidbone be fixed, it depresses the lower jaw. 
 
 The hyo-glossus arises from the body, the 
 HYO-GLOSSUS. , , ,, , , ., , . 
 
 greater and lesser cornua ot the os hyoides, and is 
 
 inserted into the posterior two-thirds of the side of the tongue, its 
 fibres blending with the stylo-glossus and palato-glossus. 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. Its action (with that of its 
 
 * Some anatomists ascribe the following names to the different origins of this 
 muscle : that from the body of the hyoid bone is termed the basio-glossus, that from 
 the greater cornu the cerato-glossus, and that from the lesser cornu the chondro-ylossus. 
 
48 
 
 SUBMAXILLARY REGION. 
 
 fellow) is to depress the tongue. Observe the several objects which 
 lie upon the hyo-glossus ; namely, the hypoglossal and gustatory 
 nerves (which at the anterior border form one or more loops of 
 communication), the submaxillary ganglion, the duct of the sub- 
 maxillary gland, and the sublingual gland. Beneath the hyo- 
 glossus muscle lie the lingual artery, part of the middle constrictor 
 
 FIG. 10. 
 
 Styloid process . . - 
 
 Glosso-pharyngeal n. 
 
 Hypoglossal n. 
 Occipital a. . 
 
 Submaxillary gan- 
 glion 
 
 Duct of submaxillary 
 gland. 
 
 Middle constrictor m. 
 
 Liugual a 
 
 Descendens noni n. . 
 
 . Chorda tyinpani n. 
 -Gustatory n. 
 
 MUSCLES, VESSELS, AKD NERVES OF THE TONGUE. 
 
 of the pharynx, part of the genio-hyo-glossus, the lingualis muscle, 
 and the glosso-pharyngeal nerve. 
 
 GENIO- The genio-hyo-glossus arises by a tendon from 
 
 HYO-GLOSSUS. the upper tubercle behind the symphysis of the 
 
 lower jaw, and is inserted as follows : the lower fibres into the 
 body of the os hyoides ; the upper fibres into 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 
 
SUBMAXILLART REGION. 49 
 
 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 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, and blends with the fibres of this muscle, as well as with 
 the palato-glossus. Its nerve comes from the hypoglossal. Its 
 action is to retract the tongue. 
 
 HYPOGLOSSAL The hypoglossal, or ninth cranial nerve, is the 
 
 NERVE. motor 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 (by two fasciculi which 
 subsequently blend), it lies beneath the internal jugular vein and 
 internal carotid artery, where it is intimately connected with the 
 lower ganglion of the pneumogastric nerve; it then comes up 
 between the artery and vein, and, immediately below the posterior 
 belly of the digastricus, curves forwards over the occipital, the 
 internal and external carotid and facial, arteries. Next it crosses 
 the hyo-glossus muscle, and passing beneath the mylo-hyoid, 
 divides into branches which supply the following muscles ; 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. 30). It also sends a nerve to the thyro-hyoideus, which proceeds 
 from it where it crosses over the external carotid, accompanied by 
 the hyoid branch of the lingual artery. Near the anterior border 
 
50 SUBMAXILLARY REGION. 
 
 of the hyo-glossus, it communicates by one or more loops with the 
 gustatory nerve. (Fig. 10.) 
 
 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 physio- 
 logically for two reasons : 1 . They account for the hypoglossal 
 nerve containing sensory fibres. 2. They contribute the greater 
 part of the filaments of the descendens noni. It is also connected 
 by small branches with the pneumogastric nerve and the superior 
 cervical ganglion of the sympathetic at the base of the skull. 
 
 SUBLINGUAL The subliugual gland lies immediately beneath 
 
 GLAND. the mucous membrane of the floor of the mouth. 
 
 Its shape is oblong, with 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 the ridge 
 felt upon the floor of the mouth. The ducts of some of the lobes 
 terminate 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. 
 
 LINGUAL OB This nerve is a branch of the inferior maxillary 
 
 GUSTATORY or third division of the fifth pair of cranial nerves. 
 
 NERVE. Emerging beneath the external pterygoid m., it 
 
 descends between the ramus of the jaw and the internal ptery- 
 goid muscle, and 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. (Fig. 10.) 
 Having reached the under part of the tongue, the nerve divides into 
 filaments which supply the papillae on its anterior three-fourths. 
 Beneath the external pterygoid it is joined at an acute angle by 
 the chorda tympani, and in its course it gives off some com- 
 
 * Aug. Quirin. Rivinus, ' de Dyspepsia.' Lips. 1678. 
 
STJBMAXILLARY REGION. 51 
 
 municating branches to the hypoglossal nerve near the anterior 
 border of the hyo-glossus. It supplies also the mucous membrane 
 of the mouth, gums, and the sublingual gland, and at the apex of 
 the tongue the terminal branches of this nerve and the hypo- 
 glossal are connected. 
 
 SUBMAXILLARY At the lower border of the gustatory nerve 
 GANGLION. before it crosses the submaxillary duct, you will 
 
 find a small ganglion, about the size of a pin's head. Like the 
 other ganglia in connection with the branches of the fifth pair, it 
 receives filaments of three different kinds viz. motor, sensory, 
 and sympathetic. Its motor root is the chorda tympani, which, 
 apparently a branch of the gustatory, is derived from the facial 
 nerve. Its sensory roots proceed from the gustatory; and its 
 connection with the sympathetic system is established by a branch 
 which comes from the nervi molles round the facial artery. The 
 ganglion supplies five or six branches to the submaxillary gland 
 and its duct. It also supplies the mucous membrane of the floor 
 of the mouth.* 
 
 LINGUAL The lingual artery is generally the second 
 
 ARTERY. branch of the external carotid. Curving slightly 
 
 upwards from its origin, the artery soon runs forwards beneath 
 the posterior belly of the digastricus, and stylo-hyoideus, and 
 then passes beneath the hyo-glossus m., 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. Under the hyo-glossus, 
 the artery lies upon the middle constrictor of the pharynx, and 
 the genio-hyo-glossus ; in the substance of the tongue, it lies 
 between the genio-hyo-glossus and the inferior lingualis. The 
 curves made by the artery are for the purpose of allowing the 
 elongation of the tongue. Its branches are : 
 
 1. The hyoid, a small artery which runs along the upper border of 
 the hyoid bone, supplying the muscles and anastomosing with its fellow. 
 
 * Meckel describes a small branch of the ganglion which sometimes passes for- 
 wards to join a branch of the hypoglossal, on the hyoglossus m., and ends in the 
 genio-hyo-glossus. 
 
 E 2 
 
52 EXTERNAL CAROTID ARTERY. 
 
 The nerve to the thyro-hyoid muscle, which is derived from the hypo- 
 glossal, accompanies this artery. 
 
 2. The dor sales linguae, two or more, 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 generally gives off the little artery 
 of the frsenum 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 branches to the tongue, and at the tip inosculates 
 slightly with its fellow. 
 
 The lingual or ranine vein commencing at the tip of the 
 tongue, runs along its under surface over the hyo-glossus, and 
 terminates in the internal jugular vein. 
 
 The best place for finding and tying the lingual artery has 
 been mentioned (p. 46). The rule laid down is trustworthy only 
 when the artery runs its normal course. We 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 
 submaxillary gland, and then passed through the mylo-hyoideus 
 to reach the tongue. 
 
 The course and relations of the external carotid artery, and its 
 branches in the neck, should now be made out. In preparing a 
 view of them, observe that nearly all the veins lie in front of their 
 corresponding arteries. In removing the connective tissue and 
 lymphatic glands, the student must take care of the nerves and 
 other structures which are liable to be injured. 
 
 COURSE AND '^^ ie ex ^ erna l carotid arises from the common 
 
 RELATIONS OF THE carotid about the level of the upper border of the 
 EXTEENAL thyroid cartilage. It ascends to the interval 
 
 CABOTID ABTEBY. between the ear and the jaw, and, at first, lies 
 beneath the sterno-mastoid, the cervical fascia, the platysma 
 myoides, and some branches of the superficial nerves. It is next 
 
BRANCHES OP THE EXTERNAL CAEOTID. 53 
 
 crossed by the hypoglossal nerve, the facial and lingual veins, the 
 posterior belly of the digastricus and stylo-hyoideus ; it then 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. 
 
 The external carotid is separated from the internal, by the 
 stylo-glossus and stylo-pharyngeus, the giosso-pharyngeal nerve 
 and the stylo-hyoid ligament. The superior laryngeal nerve lies 
 under both vessels. 
 
 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. It soon, however, 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 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. 
 
 SUPERIOR The superior thyroid, the first branch of the 
 
 THYROID ARTERY, external carotid, arises just below the great cornu 
 of the os hyoides. It lies in the superior carotid triangle, and 
 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 hyoid, a small muscular branch, runs horizontally inwards 
 below the greater cornu of the os hyoides, and anastomoses with its 
 fellow. 
 
 2. The superior laryngeal branch, accompanied by the superior laryn- 
 geal nerve, runs beneath the thyro-hyoid muscle, pierces the thyro-hyoid 
 membrane (sometimes the thyroid cartilage), and supplies the muscles 
 and the mucous membrane of the larynx. 
 
54 BRANCHES OP THE EXTERNAL CAROTID. 
 
 3. The middle 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 commu- 
 nicates with a corresponding branch on the opposite side. (Fig. 8, p. 30.) 
 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 even a perpendicular direction in front of the mem- 
 brane, and finally distributed to one of the lobes of the thyroid body. 
 We have seen several instances in which the membrane 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 it has been fairly exposed. 
 
 Among the many arterial inosculations about the thyroid body 
 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 arteries of the same side. 
 
 The superior thyroid vein crosses transversely the sheath of the 
 common carotid, and joins the internal jugular. 
 SUPERIOR *^ ne superior laryngeal nerve, mentioned as 
 
 LARYNGEAL accompanying the superior laryngeal artery, is 
 
 NEBVE. given off from the inferior ganglion of the pneumo- 
 
 gastric. It descends by the side of the pharynx, behind both 
 carotid arteries, and divides into two branches, the internal and 
 external laryngeal nerves. The internal branch enters the larynx 
 through the thyro-hyoid membrane accompanied by the superior 
 laryngeal artery, and supplies the mucous membrane of the 
 larynx with its exquisite sensibility. Some of its branches may be 
 traced upwards in the ary-epiglottidean fold to supply the epiglot- 
 tis and base of the tongue ; others descend to the rima glottidis ; 
 a large branch passes down behind the ala of the thyroid cartilage 
 
BRANCHES OF THE EXTERNAL CAROTID. 55 
 
 to join the recurrent laryngeal nerve ; and a small branch pierces 
 the arytenoideus to supply the mucous membrane beneath it. The 
 external branch accompanies the crico-thyroid artery, and after 
 distributing filaments to the pharyngeal plexus, supplies the inferior 
 constrictor and the crico-thyroid muscles. 
 
 LINGUAL The lingual artery and its branches have been 
 
 ABTEET. described (p. 51). 
 
 The facial artery and its branches below the 
 jaw have also been described (p. 45). 
 
 OCCIPITAL The occipital artery arises from the posterior 
 
 ARTERY. part o f fa e external carotid, usually opposite the 
 
 facial artery and 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 sterno- 
 mastoid, the splenius capitis, the trachelo-mastoid, and the digas- 
 tric. Arrived at the back of the head, the artery runs superficial 
 to the superior oblique, the rectus capitis posticus major and the 
 complexus, and divides into wide-spreading branches for the supply 
 of the scalp. In the first part of its course, the occipital artery 
 crosses over the internal carotid artery, the internal jugular vein, 
 the pneumo gastric and the spinal accessory nerves, and is itself 
 crossed by the hypoglossal nerve. It sends off the six following 
 branches : 
 
 1. The superior sterno-mastoid, which enters the muscle with the 
 nervus accessorius. 
 
 2. The auricular ramifies on the cranial aspect of the concha. 
 
 3. The posterior meningeal ascends with the internal jugular vein, 
 and enters the cranium through the foramen jugulare to supply the dura 
 mater of the posterior fossa. 
 
 4. The princeps cervicis, which we shall see better hereafter, is a short 
 trunk which runs down the back of the neck, and divides into two branches 
 a superficial, lying beneath the splenius, and supplying also the trapezius, 
 and a deep branch lying under the complexus, and anastomosing with 
 the deep cervical artery between this muscle and the semi-spinalis colli. 
 
 5. The mastoid enters the foramen in the mastoid process, and 
 supplies the dura mater. 
 
 6. The cranial branches supply the scalp on its posterior aspect. 
 
56 BRANCHES OP THE EXTERNAL CAROTID. 
 
 The occipital vein usually terminates in the internal jugular, 
 occasionally in the external jugular vein. 
 
 POSTERIOR Au- The posterior auricular artery, the fifth branch, 
 JUCULAB AETEET. j s given off from the posterior part of the external 
 carotid. It arises above the digastricus, lies on the styloid process, 
 and under cover of the parotid gland reaches the furrow between 
 the cartilage of the ear and the mastoid process. Before it reaches 
 the furrow, it is crossed by the facial nerve, and just beneath it is 
 the spinal accessory. Above the mastoid process it divides into 
 two branches, a posterior inosculating with the occipital, and an 
 anterior communicating with the temporal. It supplies the back 
 of the scalp and the cartilage of the ear. It gives off 
 
 1. Small branches to the digastricus, stylo-hyoid, and the parotid 
 gland. 
 
 2. The stylo-mastoid, a very constant little artery, which runs through 
 the stylo mastoid foramen to supply the mastoid cells, the vestibule, and 
 the membrana tympani, inosculating with the tympanic branch of the 
 internal maxillary. 
 
 3. The auricular branches, which supply both surfaces of the auricle. 
 
 POSTEBIOE Au- The posterior auricular nerve lies close to the 
 KICULAB NEEVE. artery of the same name. It is the first branch of 
 the seventh or facial nerve after its exit from the stylo-mastoid 
 foramen. It runs behind the ear and divides into an auricular 
 branch to the retrahens and the attollens aurem, and an occipital 
 branch to the posterior belly of the occipito-frontalis. The nerve 
 is connected with the auriculo-parotidean branch of the cervical 
 plexus, and with the auricular branch of the pneumogastric nerve. 
 
 ASCENDING This long and straight branch arises about half 
 
 PHAEYNGEAL an inch above the division of the common carotid. 
 
 ARTEET. n asc ends 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 numerous branches ; among 
 them are : 
 
 1. Small branches which pass outwards to supply the anterior recti 
 muscles, the superior cervical ganglion, the pneumogastric and hypo- 
 glossal nerves. 
 
CEEVICAL PLEXUS. 57 
 
 2. Pharyngeal branches, which pass to the pharyngeal muscles ; one, 
 the largest of all, enters the pharynx above the superior constrictor, 
 and terminates in the soft palate, the Eustachian tube, and the tonsils. 
 
 3. A meningeal branch, which passes through the foramen lacerum 
 posticum, and is distributed to the dura mater of the occipital fossa. 
 
 The examination of the two remaining branches of the external 
 carotid, the internal maxillary and temporal, must for the present 
 be postponed. Meanwhile the student should make out the deep 
 cervical plexus and its branches. 
 
 CERVICAL This plexus is formed by the anterior branches 
 
 PLEXUS OF of the four upper cervical nerves. It consists 
 
 NERVES. o f a ser i es o f loop-like communications, between 
 
 these nerves, close to the transverse processes of the four upper 
 cervical vertebrae : each nerve dividing into an ascending and a 
 descending branch, with the exception of the first. The plexus 
 is situated behind the sterno-mastoid m. 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. 20). 
 
 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. (For further course see p. 59.) 
 
 2. The communicantes noni come from the second and third cervical 
 nerves, wind round the internal jugular vein, and join the descendens 
 noni in front of the carotid sheath, forming the ' ansa hypoglossi.' They 
 supply the depressor muscles of the os hyoides and larynx. 
 
 3. Muscular branches to the recti antici, the rectus lateralis, and 
 longus colli muscles. 
 
 4. Branches which communicate with the pneumogastric, hypoglossal, 
 and sympathetic nerves, and one to join the fifth cervical. 
 
 EXTERNAL SERIES. 1. One or more branches to the nervus accesso- 
 rius : firstly in the sterno-mastoid, then in the occipital triangle, and 
 lastly beneath the trapezius. 
 
58 SCALENE MUSCLES. 
 
 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 care- 
 fully dissected. While this is being done, the student must be 
 careful not to injure the branches of the subclavian artery, the 
 lymphatic duct on the right, and the thoracic duct on the left 
 side, the nerve to the subclavius m , the phrenic nerve, the cervical 
 and the brachial plexuses of nerves, and their small branches. 
 SCALENE The scalene muscles, so called from their resem- 
 
 MUSCLES. blance to a scalene triangle, extend from the trans- 
 
 verse processes of the cervical vertebrae to the first and second ribs. 
 They may be considered as intercostal muscles, since the trans- 
 verse 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 The scalenus anticus arises from the anterior 
 
 ANTICUS. tubercles of 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 in 
 front of the groove for the subclavian artery. 
 
 SCALENUS The scalenus medius arises from the posterior 
 
 MEDIUS. tubercles of the transverse processes of all the 
 
 cervical vertebrae except the first, and is inserted into the first 
 rib behind the scalenus anticus, extending, from the tubercle, 
 -forwards for an inch and a half. 
 
 SCALENUS The scalenus posticus arises from the posterior 
 
 POSTICUS. tubercles of the transverse processes of the two or 
 
 three lowest cervical vertebrae, and is inserted into the second rib 
 between its tubercle and angle, anterior to the levator costaa. 
 
SCALENE MUSCLES. 59 
 
 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 the front of it are, the clavicle, the subclavius, the 
 clavicular origin of the sterno-mastoid, the omo-hyoid, the phrenic 
 nerve, the subclavian vein, the supra-scapular and posterior scapular 
 arteries. Behind it are the subclavian artery, the five nerves 
 which form the brachial plexus, and the pleura ; to its inner side 
 is the internal jugular vein. 
 
 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 guide to the subclavian artery, for it enables you to find the 
 outer edge of the scalenus anticus, where you must look for the 
 vessel. Is the scalenus anticus entirely concealed from view by 
 the sterno-mastoid or not ? This will depend upon the breadth of 
 the clavicular attachment of the sterno-mastoid. As a general rule, 
 it may be said that the scalene muscle is concealed by the sterno-mas- 
 toid, and that consequently, in tying the subclavian artery, it may 
 be necessary to divide partially the clavicular origin of the muscle. 
 The phrenic nerve runs down in front of the 
 scalenus anticus, 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 mam- 
 mary artery, and continues 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.* 
 
 * The phrenic nerve is joined by a filament from the sympathetic, and frequently 
 
60 SUBCLAVIAN ARTERY. 
 
 COURSE AND KELATIONS 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 the left. 
 
 EIGHT SUBCLA- The right subclavian artery is one of the two 
 VIAN ARTERY. great branches into which the arteria innominata 
 
 divides behind the sterno-clavicular joint. It runs outwards be- 
 hind the scalenus anticus, then inclines downwards over the first 
 rib, at the outer border of which it takes the name of axillary. 
 The artery describes a curve, of which the greatest convexity is 
 between the scalene muscles. The height to which the arch 
 ascends varies. Grenerally, 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 outer 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 sterno-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 
 
 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 seem- 
 ingly insignificant filament is a branch of considerable size, and forms the greater 
 portion of the phrenic itself. We have met with many instances in which this acces- 
 sory 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 
 tliis accessory branch of the phrenic in tying the subclavian artery. The patient had 
 incessant spasm of the diaphragm till he died. 
 
SUBCLAVIAN AETEEY. 
 
 61 
 
 the internal jugular and vertebral veins, by the pneumogastric 
 and phrenic nerves, and by some cardiac filaments of the sym- 
 pathetic. Inferiorly it rests upon the pleura. Behind the artery 
 are the recurrent branch of the pneumogastric, the sympathetic 
 
 FIG. 11. 
 
 3rd cervical n. 
 
 4th cervical n. 
 Pneumogas- 
 tric n. . . 
 
 5tli cervical n. 
 
 Brachial plexus 
 
 Phrenic n. . . 
 
 Line of reflec- 
 tion of peri- 
 cardium. 
 
 Cervicalis ascender s a. 
 Scalenus anticus. 
 Inferior thyroid a. 
 
 Snperflcialis 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. 
 
 nerve, the longus colli, the transverse process of the seventh 
 cervical vertebra and the apex of the lung covered with the pleura. 
 Three branches arise from this portion of the subclavian viz. the 
 vertebral, internal mammary, and thyroid axis. 
 
62 SUBCLAVIAN ARTERY. 
 
 In the second (the highest) 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 scalenus anticus and phrenic 
 nerve which separate it from the subclavian vein. Behind the 
 artery is the scalenus medius ; above it is the brachial plexus ; 
 below it is the pleura. 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 in the supra-clavicular triangle 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 subclavius muscle, with its nerve ; 
 and, what is of much more consequence, it is here crossed by the 
 external jugular and (often) the supra and posterior scapular veins ; 
 so that there is here a confluence of large veins in front of the 
 artery. The subclavian vein is situated below the artery, but on 
 a plane anterior to it. Below it is the first rib, and behind it the 
 scalenus medius. Above the artery and to its outer side, are the 
 trunk nerves of the brachial plexus and the omo-hyoid m. One of 
 these nerves (the conjoined fifth and 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. We have heard a hospital surgeon of great experience 
 say, that he had seen this mistake committed on three separate occa- 
 sions. 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-scapular. 
 
 LEFT SUBCLA- The left subclavian is the last of the three 
 
 TIAN ARTERY. great branches which arise from the arch of the 
 
 aorta. It ascends nearly vertically out of the chest, and then 
 arches in front of 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 
 
SUBCLAVIAN ARTERY. 63 
 
 pleura ; on its right side are the thoracic duct, the oesophagus and 
 the trachea ; in front are the pneumogastric and phrenic nerves, 
 the cardiac branches of the sympathetic, the left common carotid, 
 and the left lung covered with its pleura ; the left brachio-cephalic 
 vein crosses in front of it. Behind it is the longus colli muscle, 
 and the inferior cervical ganglion. 
 
 At the level of the upper part of the chest, the left sub- 
 clavian 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 the scalenus anticus, and on the surface of the first rib, 
 the relations of the left subclavian are similar to those of the right 
 (p. 62). 
 
 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. 
 
 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 
 sympathetic 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 laryn- 
 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 arching behind the internal jugular 
 vein as high as the seventh cervical vertebra, it curves downwards 
 and forwards to terminate 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 
 subclavian vein near its junction with the jugular, and searching 
 
64 SUBCLAVIAN ARTERY. 
 
 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, between the scalene muscles, 
 the artery is more accessible, although it is rarely ligatured in 
 this situation. 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 Dupuytren in the year 1819. 
 More recently it has been 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. Kemember the tubercle on the inner edge 
 of the rib which indicates the insertion of the scalenus : this 
 
 * 'Med. Chirurg. Trans.,' vol. xxix. p. 25. 
 
BEANCHES OP THE SUBCLAVIAN AETEEY. 65 
 
 tubercle is the best guide to the artery. It is necessary to divide 
 a layer of fascia which immediately covers the vessel before 
 the needle can be introduced around it. Mr. Eamsden, of St. 
 Bartholomew's Hospital, was the first who tied the subclavian in 
 the third part of its course, in the year 1 809 ; since that time the 
 operation has been repeatedly performed, with very 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 aneurysmal 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 
 distinguished anatomists have committed mistakes. Sir Astley 
 Cooper * 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.f We were present at 
 an operation in which the large nerve (a branch of the brachial 
 plexus) which runs parallel with and on a plane anterior to the 
 artery was mistaken for it and tied ; the surgeon being deceived 
 by the pulsation communicated to the nerve. 
 
 BRANCHES OF ^ e Branches of the subclavian extend so widely, 
 
 THE SUBCLAVIAN that in the present dissection we can trace them only 
 ARTERY. for a short distance. They are four in number : 
 
 1 . The vertebral. 
 
 2. The thyroid axis, a short thick trunk which gives off the 
 inferior thyroid, supra-scapular, and posterior scapular. 
 
 3. The internal mammary. 
 
 4. The superior intercostal, which gives off the deep cervical. 
 As a rule, the vertebral, the thyroid axis, and the internal 
 
 mammary are given off -from the subclavian in the first part of 
 
 * ' London Medical Review,' vol. ii. p. 300. 
 j- 'Edinburgh Med. and Surg. Journal,' vol. xvi. 1820. 
 F 
 
66 BRANCHES OP THE SUBCLAVIAN ARTERY. 
 
 its course, and the superior intercostal in the second part. 
 The most frequent deviation is, that the posterior scapular (trans- 
 versalis colli) arises from the subclavian in the third part of its 
 course.* 
 
 VEBTKBEAL This, the first and largest branch, arises from 
 
 AHTEEY. the upper 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 vertebrae. 
 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-atlantoid ligament and the dura mater, then enters the 
 skull through the foramen magnum, and unites with its fellow 
 near the lower border of the ' pons Varolii ' to form the basilar 
 artery. 
 
 Directly after the artery is given off from the subclavian, it lies 
 behind the internal jugular vein, and, on the left side, behind the 
 thoracic duct. As it lies upon the groove on the neural arch of 
 the atlas it is separated from it by the suboccipital nerve, and is 
 situated within the suboccipital triangle. 
 
 The vertebral artery is accompanied by slender nerves from 
 the inferior cervical ganglion of the sympathetic. These nerves 
 communicate 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, lateral spinal branches to the spinal cord and 
 its membranes which pass through the intervertebral foramina. 
 
 * With reference to the origin of the posterior scapular (transversalis colli) artery, 
 we made special observations during the winter session of 1858-59. We found that 
 this artery was given off most frequently, not by the thyroid axis, but by the sub- 
 clavian in the third part of its course. Under these circumstances the superficialis 
 colli a. generally came from the thyroid axis. 
 
BRANCHES OP THE SUBCLAVIAN ARTERY. 67 
 
 The cranial branches of the vertebral artery are mentioned at 
 length in the description of the arteries of the brain. 
 
 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 emerging 
 through the transverse process of the sixth, joins the brachic- 
 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 
 THYHOID Axis. 
 
 near the inner edge of the scalenus anticus, and 
 after a course of a quarter of an inch divides into three branches, 
 which take different directions ; namely, the inferior thyroid, the 
 supra-scapular, and the posterior scapular. 
 
 1. 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. Besides small branches to the trachea, the 
 oesophagus, and the larynx, it gives off 
 
 (a) the ascending cervical artery which runs up 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. 
 
 2. The supra-scapular artery (transversalis humeri) runs outwards over 
 the scalenus anticus, then directly beneath and parallel with the clavicle : 
 crossing over the third part of the subclavian artery, it passes beneath 
 the posterior belly of the omo-hyoid to the superior border of the scapula. 
 Here it is covered by the trapezius, goes above the transverse 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 
 
 F 2 
 
68 BRANCHES OP THE SUBCLAVIAN ARTERY. 
 
 subscapular, and with the posterior scapular artery. Near the notch, it 
 is joined by the supra-scapular nerve, which runs through it. The 
 branches of this artery are numerous but small, and are as follow : the 
 inferior sterno-mastoid (p. 25) ; the supra-acromial, which anastomoses 
 with the acromio-thoracic artery; articular branches to the shoulder 
 joint ; the infra-spinous, which ramifies in the infra-spinous fossa ; and 
 the subscapular, which ramifies in the substance of the subscapularis 
 muscle. 
 
 3. 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 superior angle 
 of the scapula. It then runs beneath the rhomboid muscles, which it 
 supplies, down to the inferior angle of the scapula, anastomosing freely 
 with the terminations of the supra- and sub-scapular arteries. In the 
 space between the sterno-mastoid 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, 
 to which, with the levator anguli scapulae, it is principally distributed. 
 
 The superficialis colli often comes direct from the thyroid axis. 
 
 The veins corresponding to the supra -scapular and posterior 
 scapular arteries terminate in the external jugular, sometimes in 
 the subclavian. The inferior thyroid vein crosses in front of the 
 common carotid artery, and joins the internal jugular. 
 
 INTERNAL This artery arises from the subclavian opposite 
 
 MAMMARY. to the thyroid axis. It enters the chest behind 
 
 tbe subclavian vein, and descends behind the cartilages of the ribs, 
 about half an inch from the sternum. Its further progress will be 
 examined in the dissection of the chest (p. 121). The corresponding 
 vein most frequently terminates in the brachio-cephalic. 
 
 SUPERIOR This artery is given off by the subclavian behind 
 
 INTERCOSTAL. the scalenus anticus on the right side, and to its 
 
 inner side on the left, so that you must divide the muscle to see it. 
 It enters the chest behind the pleura, to the outer side of the first 
 
BRANCHES OF THE SUBCLAVIAN ARTERY. 
 
 69 
 
 dorsal ganglion of the sympathetic. It runs over the necks of the 
 first and second ribs, and furnishes the arteries of the two upper 
 intercostal spaces, and a posterior branch which is distributed to 
 the muscles of the back and the spinal cord. It usually inoscu- 
 lates with the first inter- F JG . 12. 
 costal branch of the aorta. 
 The corresponding vein 
 terminates on the right 
 side in the vena azygos ; 
 on the left in the brachio- 
 cephalic. 
 
 DEEP CERVICAL This artery 
 ARTERY. arises from 
 
 the superior intercostal, 
 seldom direct from the 
 subclavian. It goes to the 
 back of the neck between 
 the first rib and the trans- 
 verse process of the last 
 cervical vertebra, and 
 ascends between the corn- 
 plexus and the semi-spinalis 
 colli, both of which it sup- 
 plies. It sometimes inos- 
 culates with the princeps 
 cervicis, a branch of the 
 occipital (p. 55). 
 
 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 first part of its course before it gives off any 
 branches, how would the arm be supplied with blood : The 
 answer is, by six collateral channels, as follow : 1 . By the com- 
 munications between the superior and inferior thyroid : 2. Between 
 
 DIAGRAM TO SHOW THE INOSCULATIONS OF THE 
 SUBCLAYIAN ARTERY. 
 
70 BEACHIAL PLEXUS OF NERVES. 
 
 the two vertebral : 3. Between the internal mammary and the 
 intercostals and the epigastric : 4. Between the thoracic branches 
 of the axillary, and the intercostal branches of the aorta : 
 
 5. Between the superior intercostal and the aortic intercostals. 
 
 6. Between the princeps cervicis and the deep cervical. Most 
 of these inosculations are shown in the diagram, p. 69. 
 
 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 the dorsalis scapulae, a branch 
 of the subscapular : 2. Between the supra-acromial branch of the 
 supra-scapular and the acromio-thoracic : 3. Between the posterior 
 scapular and the subscapular and dorsalis scapulae : 4. Between the 
 internal mammary, the aortic intercostals and superior intercostal 
 on the one hand, and the long and short thoracic branches of the 
 axillary, on the other. 
 
 SUBCLAVIAN The subclavian vein does not form an arch like 
 
 VEJ N. the 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 pneumogastric nerves. It has 
 a pair of valves just before its junction with the internal jugu- 
 lar. It receives the anterior jugular, the vertebral, the external 
 jugular, and through it, the supra-scapular and posterior scapular 
 veins. 
 
 BRACHIAL The l ar g e nerves forming the plexus which sup- 
 
 PLEXUS OF plies the upper extremity are the anterior divisions 
 
 NERVES. o f h e four lower cervical and the first dorsal, with 
 
 a small fasciculus derived from the fourth cervical nerve. Emer- 
 ging from the intervertebral 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 
 
BEACHIAL PLEXUS OF NEEVES. 
 
 71 
 
 axilla, completely surround the artery: one cord lying to the 
 outer side, a second lying to the inner side, and a third behind 
 the vessel. 
 
 The plexus is crossed superficially by the omo-hyoid muscle, 
 and by the supra-scapular and posterior scapular arteries. 
 
 The arrangement of the nerves in the formation of the plexus 
 
 FIG. 13. 
 
 DIAGRAM OF THE FORMATION OF THE BRACHIAL PLEXUS AND ITS BRANCHES. 
 
 c 4-8. Anterior trunks of the cervical nerves. 
 D 1. Anterior trunk of the first dorsal n. 
 9. N. to the rhomboid m. 
 
 10. Supra scapular. 
 
 11. N. to snbclavius m. 
 12-13. Anterior thoracic. 
 
 14,15,16. Subscapular n. 
 
 17. Lesser int. cutaneous. 
 
 18. Musculo-cutaneous . 
 
 19. Circumflex. 
 
 20. Median. 
 
 21. Musculo-spiral. 
 
 22. TJlnar. 
 
 23. Int. cutaneous. 
 
 24. Ext. respiratory of Bell. 
 
 is very variable, and often not alike on both sides. The most 
 usual arrangement is, that at the outer border of the scalenus 
 anticus, the fifth and sixth cervical n. unite to form an upper 
 trunk ; the eighth and the first dorsal n. form a lower trunk ; the 
 
72 BKANCHES OP THE BRACHIAL PLEXUS. 
 
 seventh cervical runs for some distance alone, and forms a middle 
 trunk. Now each of these five primary nerves divides into an 
 anterior and a posterior branch : the anterior branches given off 
 from the fifth, sixth, and seventh form the outer cord of the plexus ; 
 the anterior branches given off from the eighth cervical and first 
 dorsal form the inner cord: while the posterior branches of all 
 the nerves (namely, the fifth, sixth, seventh, eighth cervical and 
 first dorsal) unite to form the posterior cord.* 
 
 The branches arising from the plexus are best arranged into 
 those given off above the clavicle, and those given off below it. 
 The following are those given off above the clavicle. 
 
 a. The branch forming one of the roots of the phrenic arises 
 from the fifth cervical. (Not in the diagram.) 
 
 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 scaleni 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 
 cervical nerve, passes through the scalenus medius, and accom- 
 panies the posterior scapular artery, beneath the levator anguli 
 scapulae, which, as well as the rhomboid muscles, it supplies. 
 
 e. The supra-scapular nerve arises from the cord formed by 
 the fifth and sixth 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 posterior thoracic nerve (called external respiratory 
 by Sir C. Bell) to the serratus magnus arises from the fifth and 
 sixth cervical, in the substance of the scalenus medius. It passes 
 through this muscle and subsequently emerges below the rhomboid 
 
 * For a description of the arrangement of the nerves constituting the plexus, see 
 a paper by Lucas, 'Guy's Hospital Reports,' 1875; also Turner in the 'Journal of 
 Anatomy,' 1872. 
 
DISSECTION OF THE FACE. 73 
 
 nerve-; it then descends behind the plexus and the subclavian 
 vessels to the outer surface of the serratus magnus, to the several 
 digitations of which it is exclusively distributed. 
 
 g. An articular branch is distributed to the shoulder joint; 
 besides some filaments to the constituent bones. 
 
 It only remains to be observed that the upper cord of the 
 brachial plexus receives a branch from the lower cord of the cer- 
 vical, and that each of its component nerves communicates by 
 slender filaments with the sympathetic. 
 
 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) : all of which will be described more fully in the dissec- 
 tion of the arm. 
 
 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 
 largely supplied with motor and sensory 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 horse-hair, 
 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, to be properly cleaned, should 
 be stretched by hooks. 
 
74 MUSCLES OF THE FACE. 
 
 The student is recommended to make out the muscles and 
 arteries on the one side, leaving the other side for the display of 
 the nerves. 
 
 The motor nerve which supplies all the muscles of expression in 
 the face is the 'partio dura,' or facial division of the seventh cranial 
 nerve. It emerges from the stylo-mastoid foramen, and divides 
 into branches, which pass through the parotid gland, forming a 
 plexus termed the l pes anserinus.' 
 
 The sensory nerves of the face are chiefly derived from the three 
 divisions of the fifth cranial nerve ; namely, the supra-orbital, 
 the infra-orbital, and the mental. The only other nerves which 
 confer sensation upon the face are, the auriculo-parotidean branch 
 of the cervical plexus (p. 20), which supplies the skin covering the 
 parotid gland and part of the cheek ; and the naso-lobular. which 
 supplies the ala and tip of the nose. 
 
 It is convenient to arrange the muscles of the face under three 
 groups ; 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, sphincters, &c., 
 according to their respective action. 
 
 MUSCULUS Riso- This muscle arises from the fascia over the mas- 
 Kius (SANTOHINI). seter m., and passes horizontally forwards to be 
 inserted into the angle of the mouth, where it intermingles with 
 the orbicularis oris and other muscles in this situation. It produces 
 the smile, not of good humour, but of derision. This muscle is 
 usually considered as a part of the platysma myoides (p. 17). 
 
 OKBICULABIS This muscle, nearly an inch in breadth, sur- 
 
 KI8 - rounds the mouth, forming a kind of sphincter. 
 
 Its size and thickness in different individuals produce the variety 
 in the prominence of the lips. Observe that its fibres, except the 
 most internal, do not surround the mouth in one unbroken series, 
 but that those of the upper and lower lip decussate at the angles 
 of the mouth, and intermingle with the fibres of the buccinator and 
 
MUSCLES OP THE FACE. 75 
 
 other muscles which converge from different parts of the face.* 
 The cutaneous surface of the muscle is intimately connected with 
 the lips and the surrounding skin ; the deep surface is separated 
 from the mucous membrane by the labial glands and the coronary 
 vessels. . 
 
 The orbicularis is the antagonist of all the muscles which move 
 the lips. Upon a nice balance of their opposite actions depends 
 the play and infinitely varied expression of the mouth.f 
 
 DEPRESSOR This muscle arises broadly from the oblique 
 
 ANGUH ORIS. line of the lower jaw behind the foramen mentale, 
 
 and is inserted narrowly into the angle of the mouth, interming- 
 ling with the zygomatic muscles. It is an important muscle 
 in the expression of sorrowful emotions. We see its action when 
 children cry. 
 
 DE This muscle arises from the oblique line of the 
 
 LABU INFERIORS, lower jaw below the foramen mentale, and is in- 
 OR QUADRATUS swted into the lower lip. It covers the vessels 
 
 and nerves which emerge from the foramen. 
 This muscle arises from the lower jaw, from the fossa below the 
 
 LEVATORMENTI incisor teeth, and, passing down, is inserted into 
 OR LEVATOR LABU the skin of the chin. To see it, evert the lower 
 INFERIORIS. \{p anc [ remove the mucous membrane on either 
 
 side of the frsenum. There are two of them, one for each side. 
 Their action is well seen when we shave the chin, or protrude the 
 lower lip. 
 
 * The orbicularis consists of two parts, an inner or labial part, and an outer or 
 facial ; the difference in appearance of the fibres being very marked. The labial part 
 consists of pale thin fibres, forming more or less of the inner part of the orbicularis, 
 and has no attachment to bone ; the facial part is thinner but broader, and besides 
 being connected with other muscles, is attached to bone thus: in the upper lip by two 
 fasciculi on each side, one to the septum nasi, the other to the alveolar border oppo- 
 site the incisor teeth ; in the lower lip by a single fasciculus to the lower jaw on 
 each side opposite the canine tooth. 
 
 f 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. 
 
76 MUSCLES OP THE FACE. 
 
 ZTGOMATICUS The Z. major arises from the outer surface of 
 
 MAJOR AND the malar bone close to its suture with the zygoma, 
 
 MINOB - passes obliquely downwards and inwards, 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 outer 
 border of the levator labii superioris near the corner of the mouth. 
 The zygomaticus minor is often absent. The zygomaticus major 
 is the muscle of laughing : the minor expresses sadness. 
 
 Before examining the orbicularis palpebarum, notice the tendo 
 oculi. To make the tendon more apparent, the tarsal cartilages 
 should be drawn outwards. 
 
 TENDO OCULI This tendon is a thin cord about two lines * in 
 
 OR PALPEBRARUM. length, and is readily felt at the inner angle of the 
 eye by drawing the eyelids outwards. It is fixed to the nasal 
 process of the superior maxillary bone, in front of the lachrymal 
 groove, passes horizontally outwards, and divides into two diver- 
 ging 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 
 which contains it. To see this expansion we must reflect that 
 portion of the orbicularis palpebrarum 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 palpebrarum. The 
 angular artery and vein are situated on the inner side of the 
 incision. 
 
 ORBICULARIS This thin broad muscle surrounds the margin 
 
 PALPEBRARUM. of the orbit and the eyelids, forming a sphincter. 
 It is attached on the inner side to the tendo palpebrarum, to the 
 nasal process of the superior maxillary bone, to the internal angular 
 process of the frontal bone, and to the lower margin of the orbit. 
 
 * A line is the twelfth part of an inch. 
 
MUSCLES OP THE FACE. 77 
 
 From this attachment the fibres form a series of oval curves, taking 
 a wide sweep, and pass uninterruptedly round the eyelids and orbit. 
 
 The fibres which belong to the eyelids (orbicularis palpebrarum) 
 are thin and pale, and form, over each eyelid, a series of elliptical 
 curves which meet at the external canthus of the lids, and are 
 loosely attached to the external tarsal ligament. 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 ciliarisj The 
 fibres which spread over the orbital margins are thicker and redder, 
 and mingle, on the forehead, with the occipito-frontalis and corru 
 gator supercilii, on the cheek, with the elevators of the upper lip 
 and nose and the zygomaticus minor. 
 
 No fat is found on the eyelids ; nothing intervenes between 
 the skin and the muscle but loose connective tissue, that there may 
 be no impediment to the free play of the lids. 
 
 The orbicular muscle not only closes the eyelids but protects 
 the eye. When the eye is threatened, 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 it. 
 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, and notice that the lids are 
 drawn slightly inwards as well as closed. The object of this in- 
 ward motion is to direct the tears towards the inner angle of the 
 eyelids, where they are absorbed by the puncta lachrymalia. 
 
 Since the orbicular muscle is supplied by the facial nerve, it is 
 affected in facial palsy, and the patient cannot close the lids. 
 
 CORRUGATOR This arises from the inner end of the super- 
 
 SUPERCIUI. ciliary ridge of the frontal bone, and is inserted 
 
 into the under surface of the orbicularis palpebrarum and occipito- 
 
 * ' Anthropologia,' lib. v. cap. 1 0. 
 
 f Strictly speaking, the musculus ciliaris 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. 
 
78 STRUCTURE OF THE EYELIDS. 
 
 frontalis. It lies concealed beneath these two muscles, and is the 
 proper muscle of frowning. Its nerve comes from the facial. 
 
 The present being a good opportunity to examine the structure 
 and appendages of the eyelids, postpone for the present the dissec- 
 tion of the remaining muscles of the face. 
 
 The eyelids are two elliptical movable folds, consisting of 
 strata of different tissues. The upper lid is the larger, and more 
 movable, so that when the eye is closed, it is mainly by this fold. 
 The interval between the two lids is called the 'fissura palpe- 
 brarumj which terminates on the inner and outer sides, in two 
 angles, the canthi. The lids are thickest at their borders, are 
 somewhat curved, and near the inner canthus each presents a slight 
 elevation, the papilla lachrymalis, at the top of which is a small 
 opening, punctum lachrymale, to receive the tears. 
 
 CAHUNCULA The conjunctiva lines the inner surface of the 
 
 LACHBYMALIS. lids, and at the inner canthus is raised into a red 
 
 rounded eminence, called the caruncula lachrymalis. This is com- 
 posed of an aggregation of sebaceous glands covered with mucous 
 membrane. On the surface of it are minute hairs. Its use is, 
 probably, to support the inner junction of the lids. When the 
 caruncle is diminished in size by disease, the puncta lachrymalia 
 become displaced, and the tears run down the cheek. 
 
 External to the caruncula lachrymalis is a slight vertical fold 
 of conjunctiva, plica semilunaris, which is by some considered to 
 be a rudimentary membrana nictitans (the 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 num- 
 ber of minute papillse, which, when enlarged and aggregated by 
 inflammation, give rise to the disease called ' granular lids.' 
 
 The eyelashes (cilia) are placed in two or more rows along the 
 edges 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 present an 
 opposite curve. The bulbs of the lashes are situated between the 
 
STRUCTURE OF THE EYELIDS. 79 
 
 tarsal cartilage and the fibres of the orbicularis palpebrarum. 
 They are supplied with blood by the palpebral branches of the 
 ophthalmic artery which run parallel and close to the free borders 
 of the lids beneath the orbicular muscle. 
 
 STRUCTURE OF The eyelids are composed of different tissues, ar- 
 
 THE EYELIDS. ranged in successive strata one beneath the other. 
 
 They are 1. The skin : 2. The orbicularis palpebrarum : 3. The 
 tarsal cartilage, and the palpebral ligament which extends from 
 the margin of the orbit to the outer surface of the cartilage : 
 4. The expanded tendon of the levator palpebrse (in the upper lid 
 only) : 5. Meibomian glands : 6. Mucous membrane. These 
 structures are severally connected by areolar tissue, which never 
 contains fat. 
 
 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 forethought, because the sight is 
 delicate, to guard it with eyelids as with shutters, which open 
 when we want to see. and shut during sleep ; and, that even winds 
 may not hurt them, to make eyelashes in the lids for a sieve ; 
 and to furnish the parts over the eyes with eyebrows, as with 
 eaves, so that even the sweat from off the head may do them no 
 mischief? ' * 
 
 The skin of the eyelids is remarkably smooth and delicate. It 
 is abundantly supplied with sensory 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. 76). 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 
 
 * Xenophon's Memorabilia, b. 1. c. iv. 6 : ov SoKe? ao\. Kal r6$e trpovoias fpyovtoucf- 
 vai, 76, 4vf\ affBev^is fnev IGTIV j] otyts, f)\e<f>dpoi$ avTrjv OvpHtrai, fi, 8-rav fj.(v avrfj %pricrai 
 n 57, a>a.ircT<ii>i>vra.i, 4v Se Ttf virvtf <rvyK\eifTai ; &s 8' av jurjSe favepoi $X6.irT<a<riv, rj 
 /3\e<fiapt5as t/j.Qvffai 6<f>pvfft re airoytiffuffat ra inrtp rwv o^ndraiv, is MlS' ^ fit 
 Kf(pa\ris IS 
 
80 STKUCTURE OP THE EYELIDS. 
 
 unites with the broad tarsal ligament, and is lost on the upper 
 surface of the superior tarsal cartilage. 
 
 TAKSAL CAETI- These are plates of dense fibre-cartilage which 
 LAGES AND LioA- support and give shape to the eyelids. There is 
 MENTS - one for each lid, and they are connected at the 
 
 angles (commissures or canthi) of the lids through the me- 
 dium of fibrous tissue. They can be best examined 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 main- 
 tained in position by the tendo palpebrarum (p. 76), 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, and are denser at the outer part of the orbit. There 
 are two of them, termed upper and lower, and proceeding to each 
 cartilage respectively. When an abscess forms in the connective 
 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 
 bevelled 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 lachrymalia. According to 
 our observation, this channel does not exist ; for when the lids are 
 closed, their margins are in such accurate apposition, that not the 
 slightest interspace can be discovered between them. 
 
 PUNCTA The puncta lachrymalia are two pin-hole aper- 
 
 LACHBTMALIA. tures, easily discovered 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. 
 The upper canaliculus, the longer and narrower of the two, ascends 
 
STRUCTURE OP THE EYELIDS. 81 
 
 for a short distance nearly vertically, and then dilating into a small 
 pouch makes a sharp bend inwards for about a quarter of an inch 
 to join the lachrymal sac ; the lower canal descends perpendicularly, 
 and, like the upper, makes a sharp bend, after which it pursues a 
 direction upwards and inwards to the sac. The two canals open 
 separately into the sac (sometimes by FlG 14 
 
 a commoD orifice). 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 con- 
 tracted puncta, or of slitting up the 
 lachrymal ducts, it is necessary to 
 know the exact direction of these 
 canals. (See diagram.) When from 
 any cause the tears are secreted in 
 greater quantity than usual, they overflow and trickle down the cheek 
 MEIBOMIAN These compound sebaceous glands, so called 
 
 GLANDS. after the anatomist* who first described them, 
 
 are situated on the under surface of each of the tarsal carti- 
 lages. In the upper lid there are between twenty and thirty ; 
 not quite so many in the lower. On everting the lid, they are 
 seen running in longitudinal rows in grooves of the cartilage. 
 Under the microscope, they are seen to consist of a straight central 
 tube, round the sides of which are a number of openings leading 
 to short caecal dilatations. The orifices of these glands are situated 
 on the free margin of the lids behind the lashes. They are lined 
 with flattened epithelial cells which, in the csecal dilatations, 
 become cubical. Their function is to secrete a sebaceous material, 
 which prevents the lids from sticking together. 
 
 Let us now examine the muscles in connection with the nose : 
 namely the pyramidalis nasi, the compressor naris or alse nasi, 
 and the depressor al nasi. All are supplied by the facial nerve. 
 
 * H. Meibom, 'De yasis palpebrarum novis.' Helmstedt, 1666. 
 G 
 
82 MUSCLES OF THE FACE. 
 
 PTRAMIDAMS This is situated on the bridge of the nose, one 
 
 NASI - on each side of the mesial line, and is usually 
 
 regarded as a continuation of the occipito-frontalis (p. 2). The two 
 muscles diverge as they descend, and their fibres blend with those 
 of the compressor naris. Their action produces transverse wrinkles 
 of the skin at the root of the nose, as in the expression of an 
 aggressive feeling. 
 
 COMPBESSOR This muscle is triangular, and arises by its 
 
 NAHIS. apex from the canine fossa of the superior max- 
 
 illa, and is attached to a broad thin aponeurosis which spreads 
 over the dorsum of the nose, and joins its fellow. The origin of 
 this muscle is concealed by the levator labii superioris alseque 
 nasi. 
 
 When the preceding muscle is reflected from its junction with 
 its fellow, a small nerve is seen running down towards the tip of 
 the nose. This nerve is the superficial branch of the nasal nerve 
 (called also naso-lobular). It becomes subcutaneous between 
 the nasal bone and the cartilage, and supplies the tip and lobule 
 of the nose. It is joined by a branch of the facial nerve at its 
 termination. 
 
 DEPRESSOR AIM This arises from the superior maxilla, above 
 NASI - the second incisor tooth, and is inserted into the 
 
 septum and ala of the nose. It is situated between the mucous 
 membrane and the muscular structure of the upper lip ; so that, 
 to expose it, the upper lip must be everted, and the mucous mem- 
 brane removed. 
 
 Besides the muscles above described, we find in connection 
 with the cartilages of the alee of the nose, pale muscular fibres which 
 have no very definite arrangement and require a lens for their 
 detection. Some anatomists describe a ' dilatator naris posterior' 
 as arising from the nasal process of the superior maxilla and the 
 sesamoid cartilages, and inserted into the skin of the margin of 
 the nostril ; also a dilatator naris anterior, which descends verti- 
 cally from the cartilage of the aperture to its free margin. The 
 action of these diminutive muscles is to raise and evert the ala of 
 the nose, and to counteract its tendency to be closed by atmo- 
 
MUSCLES OF THE FACE. 83 
 
 spheric pressure. In dyspnoea, and in certain mental emotions, 
 they contract with great energy. 
 
 LETATOH LABU This arises from the nasal process of the su- 
 SUPERIORIS perior maxillary bone near its orbital margin, and 
 
 AL^EQUE NASI. passing downwards divides into two portions : au 
 inner, inserted into the side of the ala of the nose ; an outer, into 
 the upper lip, where its fibres blend with the orbicularis oris and 
 levator labii superioris. It acts chiefly in expressing the smile of 
 derision. Its habitual use occasions the deep furrow which, in most 
 faces, runs from the ala of the nose towards the corner of the mouth. 
 
 LEVATOR LABU This arises from the lower margin of the orbit, 
 SUPERIORIS i.e. from the superior maxilla and malar bone, 
 
 above the infra-orbital foramen, and is inserted 
 into the upper lip, where its fibres blend with the orbicularis oris. 
 It is nearly an inch in breadth at its origin, which covers the 
 infra-orbital vessels and nerves, and is itself overlapped by the 
 orbicularis palpebrarum. 
 
 LEVATOR This muscle, which is covered by the levator 
 
 ANGULI ORIS. labii 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 the orbicularis oris, the zygomatici, and 
 the depressor anguli oris. 
 
 The buccinator arises from the outer surface of 
 the alveolar borders of the upper and lower jaws, 
 corresponding to the molar teeth, and from the ptery go-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, while the upper fibres pass to the upper lip, and 
 the lower fibres pass to the lower lip. The muscle is covered on 
 its inner aspect by the mucous membrane of the cheek, and on its 
 outer by a thin fascia which passes backwards, and is continuous 
 with that covering the pharynx. 
 
 The buccinator is the principal 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- 
 
 G 2 
 
84 
 
 MUSCLES OF THE FACE. 
 
 tion between the buccinator and the superior constrictor is the 
 ptery go-maxillary ligament. Now this ligament (see diagram) 
 extends from the Iwnular process vertically to the posterior 
 extremity of the mylo-hyoid ridge of the lower jaw near the last 
 
 FIG. 15. 
 
 Tensor palati. 
 Levator palati. 
 
 Orbieularis oris . 
 
 Pterygo-maxillary 
 
 ligament . . - 
 
 Mylo-hyoideue . 
 
 Os-hyoides . . . 
 Thyro-hyoid liga- 
 ment . . . . 
 
 Pomum Adami 
 
 Cricoid cartilage 
 Trachea . .. . 
 
 Gloeso-pharyngeal n. 
 Stylo-pharyngeus. 
 
 Superior laryngeal 
 n. and a. 
 
 External laryngeal n. 
 Crico-thyroideus. 
 
 Inferior laryngeal n. 
 (Esophagus. 
 
 MUSCLES OF THE PHARYNX. 
 
 molar tooth. 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 molar tooth of the 
 upper jaw. 
 
ARTEEIE8 OF THE FACE. 85 
 
 The chief use of the buccinator is to keep the food between the 
 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 
 supplied by the facial nerve, and is, therefore, affected in facial 
 paralysis. 
 
 The buccinator muscle is covered by a thin 
 BUCCAL FASCIA. . 
 
 layer of fascia, which adheres closely to its surface, 
 
 and is attached to the alveolar border of the upper and lower 
 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 density of this fascia, abscesses do not readily 
 burst into the mouth or the pharynx. 
 
 BUCCAL AND The buccal glands, in structure compound race- 
 
 MOLAR GLANDS. mose like the salivary, are situated between the 
 buccinator and the mucous membrane. They resemble the labial 
 glands found beneath the mucous membrane of the lips, though 
 somewhat smaller. Three or four other glands, about the size 
 of a little split pea, should be made out, as they lie between the 
 masseter and buccinator; these are the molar glands. Their 
 secretion, said to be mucous, 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 helps to fill up the zygomatic fossa, 
 and being soft and elastic, presents no 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 branch of the external carotid. It runs 
 
 tortuously beneath the hypoglossal nerve, the posterior belly of the 
 
 digastricus and the stylo-hyoideus, next through or under the 
 
 substance of the submaxillary gland, and mounts over the base of 
 
86 ARTERIES OF THE FACE. 
 
 the jaw at the anterior edge of the masseter muscle. Up to this 
 point we traced it in the dissection of the neck (page 45). 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 on the 
 face, the 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 : 
 
 a. The inferior labial artery passes inwards under the depressor 
 anguli oris and inosculates with the mental branch of the inferior dental, 
 tlie inferior coronary, and the submental arteries. 
 
 b. The inferior coronary artery comes off near the angle of the mouth, 
 either directly from the facial, or in common with the superior coronary. 
 It runs tortuously along the lower lip, beneath the depressor anguli oris ; 
 it then pierces the orbicularis, running between this muscle and the 
 mucous membrane of the lip. It inosculates largely with its fellow, the 
 inferior labial and the mental arteries. 
 
 c. The superior coronary proceeds along the upper lip close to the 
 mucous membrane, and inosculates with its fellow ; thus is formed 
 round the mouth a complete arterial circle, which can be felt pulsa- 
 ting on the inner side of the lip, near the free border. From this 
 circle numerous branches pass off to the papillae of the lips, and the 
 labial glands. The superior coronary gives off a branch, the artery of 
 the septum, which ascends along the septum to the apex of the nose ; 
 also a small one to the ala nasi. 
 
 d. The lateral artery of the nose, a branch of considerable size, arises 
 opposite the ala nasi beneath the levator labii superioris alseque nasi, 
 ramifies upon the external surface of the nose, and inosculates with the 
 nasal branch of the ophthalmic artery, the infra-orbital, and the artery of 
 the septum. 
 
 e. The angular artery, which may be regarded as the termination of 
 the facial, inosculates on the inner side of the tendo palpebrarum with 
 the nasal branch of the ophthalmic artery. 
 
ARTERIES OF THE PACE. 87 
 
 The facial artery supplies numerous branches to the muscles of 
 the face, and inosculates with the transversalis faciei, infra-orbital, 
 the mental, the sublingual branch of the lingual, the nasal 
 branches of the internal maxillary, the buccal, and the ophthalmic 
 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.* 
 
 The facial vein does not run with the artery, but takes a 
 straight course from the inner angle of the eye to the anterior 
 border of the masseter. In this course it descends upon the 
 levator labii superioris, then passes beneath the zygomatic 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 increased in size 
 by a communicating branch from the infra-orbital vein, and by a 
 large vein which conies from a venous plexus pterygoid plexus 
 deeply seated behind the superior maxillary bone. The other 
 veins which empty themselves into the facial correspond with the 
 branches given off from the facial artery. 
 
 AKTEEIA This artery arises from the temporal or the 
 
 TRANSVERSALIS external carotid in the substance of the parotid 
 FACIEI. gland. It runs forwards across the masseter 
 
 * MM. Bernard and Brown-S^quard 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. 
 
88 PAROTID GLAND. 
 
 between the parotid duct and the zygoma, 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. 
 
 The parotid gland is now to be examined. Its boundaries, its 
 deep relations, the course of its duct, and the objects contained 
 within the gland, must be carefully observed. 
 
 PABOTID The parotid, the largest of the salivary glands, 
 
 GLAND - occupies 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 externus and the mastoid process ; in front, it 
 lies over the ascending ramus of the jaw, and is prolonged for some 
 distance over the masseter. It is separated from the subinaxillary 
 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 
 strong layer of fascia, a continuation of the cervical. It not only 
 surrounds the gland, but sends down numerous partitions which 
 form a framework for its lobes. The density of this sheath explains 
 the pain caused by inflammation of the gland, the tardiness 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 be 
 in contact with the internal jugular vein. 
 
 That portion of the gland which lies on the masseter muscle is 
 called glandula socia 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. 
 
PAEOTID GLAND. 89 
 
 The duct of the parotid gland (ductus Stenonis*), about 
 two inches long, is very thick and strong. In this respect it 
 differs from the duct of the submaxillary gland, which is less 
 exposed to injury. It runs transversely forwards over the mas- 
 seter, about an inch below the zygoma, through the fat of the 
 cheek, then 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. 
 
 The direction of the parotid duct corresponds with a line drawn 
 from the middle of the lobule of the ear to a point midway between 
 the nose and the mouth. 
 
 On carefully removing the substance of the parotid gland, the 
 following structures are seen in its interior, proceeding in the order 
 of their depth from the surface : 
 
 1. Two or more small lymphatic glands. 
 
 2. The pes anserinus, or primary branches of the facial 
 nerve. 
 
 3. Branches from the auriculo-parotidean and temporo-auri- 
 cular nerves which communicate in its substance with the facial 
 nerve. 
 
 4. The external jugular vein formed by the junction of the 
 internal maxillary and temporal veins. 
 
 5. The external carotid artery, which, after distributing many 
 branches to the gland, divides, opposite the neck of the jaw, into 
 the internal maxillary and temporal ; the latter giving off in the 
 gland the auricular and transverse facial arteries.f 
 
 * Nic. Steno, 'De glandulis oris,' etc. Ludg. Bat. 1661. 
 
 j- Reviewing the intimate and deep connections of the parotid gland, one cannot 
 but conclude that it is almost 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 
 
90 NEBVES OF THE PACE. 
 
 The lymphatic glands about the parotid deserve notice, since 
 they are liable to become enlarged, and simulate disease of the 
 parotid itself. A lymphatic 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. 
 
 The parotid belongs to the compound racemose form of glands. 
 Tracing its main duct into the substance of the gland, we find that it 
 divides into smaller ones, which again subdivide into the small ra- 
 muscules which terminate in caecal dilatations or saccules. Each, saccule 
 about -j-^Viy f an i nc h ^ n diameter is filled with flattened, spheroidal 
 epithelium, inclosing a nucleus, some of them having an outstanding 
 process from the base of the cell. The saccule bas a more or less de- 
 veloped basement membrane upon which tbe flattened cells rest. An 
 aggregation of these saccules forms a small lobule, from which a small 
 excretory duct proceeds ; the lobules are united by intervening connective 
 tissue, wbicb is a continuation inwards of tbe dense fascia covering the 
 gland. Tbe small ramuscules bave only a basement membrane witb 
 flattened cells, which rapidly change in the smaller ducts to a columnar 
 form, while in tbe larger ducts tbe epithelium assumes tbe squamous 
 variety. 
 
 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. 
 
 PORTIO DURA, This is one of the divisions of the seventh pair 
 
 OR FACIAL NERVE, of cranial nerves, and is the motor nerve of the 
 face. It supplies all 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 
 
 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 ('Principles of Surgery,' 
 vol. iii. p. 262). Other surgeons, too, of more modern date, have attempted the same 
 thing. It is not unlikely that they have mistaken a tumour in the substance of the 
 parotid for disease of the parotid itself. 
 
NERVES OP THE FACE. 91 
 
 petrous portion of the temporal bone, and leaves the skull at the 
 stylo-mastoid foramen. Its course and connections in the temporal 
 bone will be studied 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 artery and the external jugular vein, and form, by their 
 communications within the substance of the parotid, the plexus 
 called pes anserinus, from its fancied resemblance to the skeleton 
 of a goose's foot. (Diagram, p. 4.) 
 
 Close to the stylo-mastoid foramen, the facial nerve gives off 
 its posterior auricular branch (p. 4), which ascends behind the 
 ear and divides into two, an auricular and an occipital ; the former 
 supplies the retrahens and attollens aurem, the latter the posterior 
 belly of the occipito-frontalis. This branch communicates with the 
 great auricular n. and with the auricular branch of the pneumo- 
 gastric. Its two next branches supply the posterior belly of the 
 digastricus and the stylo-hyoideus. The digastric nerve enters the 
 muscles by many filaments ; the nerve to the stylo-hyoid is long 
 and enters the muscle about the middle. The digastric branch 
 communicates with the glosso-pharyngeal near the base of the 
 skull : the stylo-hyoid branch with the sympathetic on the external 
 carotid a. These two muscular nerves are frequently given off 
 from a common branch. 
 
 The temporo-facial division, the larger of the two, crosses 
 the external carotid and the neck of the jaw, receives two or 
 more communications from the auriculo-temporal (branch of the 
 fifth) and subdivides into temporal, malar, and infra-orbital 
 branches. 
 
 The temporal branches ascend over the zygoma, supply the frontalis, 
 the attrahens aurem, the orbicularis palpebrarum, the corrugator super- 
 cilii, and tensor tarsi, and communicate with filaments of the supra-orbital 
 nerve, with the temporal branch of the superior maxillary n., and with 
 the auriculo-temporal n. 
 
92 NERVES OP THE FACE. 
 
 The malar branches cross the malar bone, supply the orbicular 
 muscle, and communicate with filaments of the lachrymal, the supra- 
 orbital, the superior maxillary, and the malar branch of the superior 
 maxillary. 
 
 The infra- orbital branches are the largest, and proceed transversely 
 forwards beneath the zygomatici over the masseter, to supply the orbicu- 
 laris oris, the elevators of the upper lip, and the muscles of the nose. Be- 
 neath the levator labii superioris there is a free communication with the 
 infra-orbital branches of the superior maxillary nerve, forming the infra- 
 orbital plexus. Along the side of the nose the terminal filaments join 
 the nasal and infra-trochlear branches of the ophthalmic. 
 
 The cervico-facial division, joined in the parotid gland by 
 filaments from the auriculo-parotidean (branch of the 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 communicate with the 
 buccal branch of the inferior maxillary nerve (third 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 inferior dental nerve. 
 
 The infra-maxillary or cervical branches, one or more in number, 
 were dissected with the neck (p. 21). They arch forwards below the jaw 
 covered by the platysma, as low as the hyoid bone, and communicate 
 with the superficial cervical (branch of the cervical plexus). 
 
 Respecting the function of the facial nerve, it is, at its 
 origin, purely a motor nerve ; but after leaving the stylo-mastoid 
 foramen it becomes a compound nerve, in consequence of the 
 filaments which it receives from the auriculo-temporal branch 
 of the fifth, and from the auriculo-parotidean branch of the 
 cervical plexus. These communications explain the pain which 
 is often felt in facial paralysis along the track of the facial 
 nerves. 
 
NERVES OF THE FACE. 93 
 
 SENSOBT These are the supra-orbital, the supra- and infra- 
 
 NEBVES OF THE trochlear, the naso-lobula,r, the temporo-malar, 
 FACE> the infra-orbital, and the mental, all branches of 
 
 the fifth pair. 
 
 The supra-orbited nerve is a branch of the first division 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, 
 which supply the skin of the forehead, upper eyelid, and scalp. It 
 communicates with the facial nerve on the forehead. The supra- 
 orbital artery is a branch of the ophthalmic. 
 
 The supra-trochlear n., or internal frontal, appears at the 
 inner angle of the orbit, and sends down, in front of the pulley of 
 the obliquus superior oculi, a loop to communicate with the infra- 
 trochlear. Its further course has been described (p. 4). 
 
 The infra-trochlear n. issues from the orbit below the pulley, 
 and supplies branches to the eyelids, the mucous membrane, 
 lachrymal sac, and the side of the nose. 
 
 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 (naso-lobular) of the first division of the fifth ; 
 the labial, by far the most numerous, descend into the upper lip, 
 and eventually terminate in lashes of filaments, which endow the 
 papillae of the lip with exquisite sensibility. Close to the infra- 
 orbital foramen is the infra-orbital plexus, before alluded to (p. 92). 
 The infra-orbital artery is the terminal branch of the internal 
 maxillary ; it supplies the muscles, the skin, and the front teeth 
 of the upper jaw, and inosculates with the transverse facial, buccal, 
 facial, and coronary arteries. 
 
 The naso-lobular nerve is distributed to the tip and lobule of 
 the nose, and is joined by filaments from the facial nerve. 
 
94 TEMPORAL REGION. 
 
 The temporo-mala/r nerve, one or more (branch of the supe- 
 rior maxillary), issues through the canal in the malar bone and 
 supplies the cheek and side of the temple. 
 
 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. It 
 communicates with the facial nerve. 
 
 The mental artery is a branch of the inferior dental. It sup- 
 plies the gums and the chin, and inosculates with the sub-mental, 
 the inferior labial, and inferior coronary arteries. 
 
 MUSCLES OF MASTICATION. TEMPORAL AND PTERYGO-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. 
 
 Eeflect the skin of the temple from below upwards. Beneath 
 the skin you come upon a layer of tough connective 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. 
 
 TEMPORAL This is the smaller of the two terminal branches 
 
 ARTERY. of the external carotid. Arising in the sub- 
 
 stance of the parotid gland near the neck of the jaw, it passes 
 over the root of the zygoma, close to the meatus auditorius, 
 ascends for about 1^ inches on 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 
 
TEMPORAL REGION. 95 
 
 aurem ; here it is accompanied by the auriculo-temporal branch 
 of the inferior division of the fifth nerve. It gives off the follow- 
 ing branches : 
 
 a. Several small branches to the parotid gland, the temporo-maxillary 
 articulation, and the masseter. 
 
 b. The transversalis faciei (p. 87). 
 
 c. The anterior auricular branches, two in number, superior and 
 inferior, 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 temporal muscle, 
 anastomoses with the temporal branches of the internal maxillary. 
 
 Of the two branches into which the temporal divides, the anterior 
 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 occipital and posterior auricular. 
 The anterior branch, although the smaller, is usually selected for 
 arteriotorny, the posterior being covered by a strong and unyielding 
 fascia. 
 
 ATJHIOTLO-TEM- This nerve supplies the temple and side of the 
 POBAT, NBEVB. head with common sensation. It arises from the 
 third division of the fifth pair by two roots (between which the 
 middle meningeal artery runs). From its origin it proceeds out- 
 wards beneath the external pterygoid, between the neck of the jaw 
 and the internal lateral ligament. It then ascends beneath the 
 parotid, over the root of the zygoma, where it accompanies 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 auriculo-temporal nerve sends 
 round the external carotid artery communicating branches to the 
 upper division of the facial nerve, endowing it with common sen- 
 sibility. It here distributes branches to the parotid gland, the 
 meatus auditorius, the membrana tympani, and the articulation of 
 the jaw. Above the zygoma it gives off two filaments (auricular], 
 an upper and a lower ; the upper ramifies in the skin of the outer; 
 
96 TEMPOEAL REGION. 
 
 aspect of the ear, mainly on the tragus and upper half of the auricle ; 
 the lower supplies the lobule and lower part of the pinna. 
 
 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 palpebrarum, tensor tarsi, and 
 corrugator supercilii. 
 
 MASSETEE This muscle arises from the lower edge of the 
 
 MUSCLE. zygoma, and is inserted into the outer side of the 
 
 ramus and coronoid process of the jaw. The masse ter is com- 
 posed 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 tendinous 
 fibres which occupy the front border of the muscle, and send 
 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, mainly muscular (which are concealed by the 
 parotid gland), arise from the posterior third of the zygoma, incline 
 forwards, and are inserted into the upper half of the ramus a,nd 
 the coronoid process. Besides these, a few fibres, arising from the 
 inner surface of the zygoma, are inserted into the coronoid pro- 
 cess and the tendon of the temporal muscle. Its action is to 
 raise the jaw and help to masticate the food. 
 
 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. 
 
 Reflect the masseter from its origin and turn it 
 
 DISSECTION 
 
 downwards. Observe the direction of the super- 
 ficial and deep fibres, and the tendinous partitions which augment 
 the power of the muscle by increasing its extent of origin. The 
 masseteric nerve and artery enter the under surface of the muscle 
 near to its posterior border, through the sigmoid notch of the 
 jaw ; the artery comes from the internal maxillary, the nerve from 
 the motor division of the inferior maxillary. 
 
 TEMPORAL This strong shining membrane covers the tem- 
 
 APONEUEOSIS. poral muscle ; its chief use being to give additional 
 
PTERYGO-M AXILLARY KEGION. 97 
 
 origin to its fibres. 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 superior 
 maxillary nerve. The density of this aponeurosis explains why 
 abscesses in the temporal fossa rarely point outwards ; the pus 
 generally makes its way, beneath the zygoma, into the mouth. 
 
 Eeflect 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. 
 
 TEMPORAL This muscle arises from the whole of the tem- 
 
 MUSCLE. poral fossa (except the malar surface) and the tem- 
 
 poral aponeurosis. Its fibres converge to a strong tendon which is 
 inserted into the inner surface, the apex, and anterior border of 
 the coronoid process. 
 
 The fibres of the 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. Its nerves (two deep temporal) are branches 
 of the inferior maxillary (p. 104). 
 
 Between the posterior border of this muscle and the neck of 
 the inferior maxilla, the masseteric nerve and artery pass to their 
 destination : in front of the muscle, the buccal branch of the inferior 
 maxillary nerve descends to the buccinator with its companion 
 artery. 
 
 PTEHTGO-MAX- Divide the zygomatic arch on each side of the 
 ILLAKT REGION. masseter, and turn it down, to expose the coronoid 
 process of the jaw, the insertion of the temporal muscle, and the 
 loose fat which surrounds it. Next, saw through the 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. 
 
 H 
 
98 
 
 PTERYGO-MAXILLARY REGION. 
 
 DISSECTION. 
 
 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 Key'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, the inferior 
 maxillary nerve, and the internal lateral ligament of the lower jaw. 
 All these structures are imbedded in loose soft fat, which must be 
 cautiously removed without injuring them. 
 
 Anterior deep temporal n. and a. 
 
 FIG. 16. 
 
 External pterygoid m. 
 
 Posterior deep temporal n. and a. 
 Masse teric n. and a. 
 
 Infra-orbital a . , 
 
 Spheno-maxillary 
 
 fossa . . . . 
 
 Superior dental a . 
 Buccal a . . . . 
 
 Parotid duct . . 
 
 Buccal n . . . , 
 
 Pterygo-maxillary 
 
 ligament . . . 
 
 Inter-articular 
 fibro-cartilage. 
 
 Temporal artery 
 and auriculo- 
 temporal nerve. 
 
 Middle meningeal a. 
 
 Inferior dental a. 
 Inferior dental n. 
 Gustatory n. 
 Mylo-hyoid n. 
 Internal pterygoid m. 
 
 PTSRYGOID MUSCLES AND INTERNAL MAXILLARY ARTERY. 
 
 EXTERNAL 
 PTERYGOID. 
 
 This muscle arises by two heads, one, the upper, 
 from the great wing of the sphenoid and from the 
 ridge below it ; the lower, from the outer surface of the external 
 pterygoid plate, a few fibres taking origin from the outer side 
 
PTEEYGO-MAXILLAEY EEGION. 99 
 
 of the tuberosities of the palate and superior maxillary bones. It 
 is inserted into the neck of the jaw, and slightly into the border 
 of the inter-articular nbro-cartilage of the jaw. 
 
 The advantage of the insertion of some of its fibres into the 
 inter-articular cartilage is, that the cartilage follows the condyle 
 in all its movements. When the jaw is dislocated, it is chiefly by 
 the action of this muscle, which draws the condyle forwards into 
 the zygomatic fossa ; the inter-articular cartilage being dislocated 
 with the condyle. 
 
 INTERNAL This muscle arises from the inner surface of the 
 
 PTEBTOOID. . external pterygoid plate of the sphenoid bone, and 
 
 the tuberosity of the palate bone. It is inserted into the inner 
 side of the angle of the jaw, as high as the dental foramen. 
 
 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. The 
 internal pterygoid has tendinous septa like the masseter. Both 
 the pterygoids get their nerves from the motor division of the 
 inferior maxillary. 
 
 The pterygoid muscles 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. 
 
 Saw through the neck of the jaw, disarticulate 
 the condyle with its fibro-cartilage from the 
 glenoid cavity, and turn it forwards with the external pterygoid, 
 so that the condyle can be replaced if desirable. A little dissec- 
 tion will bring into view the internal lateral ligament, and the 
 internal maxillary artery. 
 
 INTERNAL MAX- This is the larger of the two terminal branches 
 ILLARY AHTERT. into which the 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 Bpheno-maxillary fossa between the two heads of the 
 
100 
 
 INTERNAL MAXILLARY ARTERY. 
 
 external pterygoid, and terminates by dividing into numerous 
 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. 
 
 BEANCHES OF THE INTERNAL MAXILLARY ARTERY IN THE THREE 
 STAGES OF ITS COURSE. 
 
 BRANCHES IN THE FIBST 
 STAGE. 
 
 a. Tympanic. 
 
 b. Meningea media. 
 
 c. Meningea parva. 
 
 d. Inferior dental. 
 
 BRANCHES IN THE SECOND 
 STAGE. 
 
 Six to the five muscles of 
 mastication, namely : 
 f. Masseteric. 
 
 f. Anterior and posterior 
 
 temporal. 
 
 g. External and internal 
 
 pterygoid. 
 h. Buceal. 
 
 BRANCHES IN THE THIRD 
 
 STAGE. 
 
 t. Superior dental. 
 j. Infra-orbital. 
 k. Descending palatine. 
 I. Vidian. 
 
 m. Ptery go-palatine. 
 n. Nasal or spheno-pala- 
 tine. 
 
 BRANCHES m a. The tympanic ascends behind the articulation of 
 
 THE FIRST PART. the jaw, and passes through the Glaserian fissure to the 
 tympanum. It supplies that cavity and the membrana tympani, and 
 anastomoses with the stylo-mastoid and "Vidian arteries. This artery 
 is not infrequently given off from a branch of the internal maxillary 
 artery. 
 
 b. The middle meningeal artery ascends between the two roots of 
 the auriculo-temporal nerve, behind the external pterygoid, and enters 
 through the foramen spinosum into the cranium, where it ramifies 
 between the dura mater and the bones. Its further course is described 
 at p. 12. 
 
 c. The meningea parva (not marked in the plan) 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 pro- 
 
INTERNAL MAXILLAET ARTERY. 
 
 101 
 
 ceeds 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 
 foramina in the fangs, and supply the pulp in their interior. Opposite 
 the foramen mentale arises the mental branch already described (p. 94). 
 Before entering the dental foramen the artery furnishes a small branch 
 mylo-hyoid which accompanies the nerve proceeding to the mylo-hyoid 
 muscle. 
 
 BEANCHES IN e. The masseteric branch passes through the sigmoid 
 
 THE SECOND PART, notch of the jaw to the under surface of the masseter, 
 with the masseteric nerve, and inosculates with the facial artery. 
 
 FIG. 17. 
 
 Third stage. Second stage. First stage. 
 
 PLAN OF INTERNAL MAXILLARY ARTERY. 
 
 f. The anterior and posterior temporal arteries ascend to supply the 
 temporal muscle, ramifying between the muscle and the bone, one near 
 the front, the other near the posterior border of the muscle. They com- 
 municate with the superficial and middle temporal arteries, and with the 
 terminal branches of the lachrymal a. 
 
 g. The pterygoid branches supply the internal and external pterygoid 
 muscles. 
 
 h. The buccal branch runs forward with the buccal nerve to the 
 buccinator, where it anastomoses with the facial artery. 
 
102 INTERNAL MAXILLARY ARTERY. 
 
 BEANCHES IN i. The superior dental branch runs along the tube- 
 
 fHE THIRD PAET. rosity 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, and the mucous membrane of 
 the antrum. 
 
 j. The infra-orbital branch ascends through the spheno-maxillary 
 fissure, then runs forward 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 incisor and canine teeth, and upwards into 
 the orbit to the inferior oblique and inferior rectus. After issuing from 
 the foramen it sends upward branches to the lachrymal sac, and descending 
 branches to the upper lip. The former anastomose with the nasal 
 branches of the ophthalmic and facial arteries; the latter with the 
 superior coronary, transverse facial, and buccal arteries. 
 
 k. The descending palatine, a branch of considerable size, runs down 
 the posterior palatine canal with the palatine nerve (a branch from 
 Meckel's ganglion), and then along the roof of the hard palate, towards 
 the anterior palatine canal, in which, much diminished in size, it inoscu- 
 lates 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. 
 
 I. The Vidian, an insignificant branch, runs backwards through the 
 Vidian canal with the Vidian nerve, and is distributed to the Eustachian 
 tube, the pharynx, and the tympanum. 
 
 TO. The ptery go-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. 
 
 n. 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, the 
 ethmoidal cells, and the antrum. One large branch, the artery of the 
 septum, runs along the septum nasi towards the anterior palatine canal, 
 where it joins the descending palatine a. 
 
 Observe that all the branches of the internal maxillary artery 
 in the first and third parts of its course traverse bony canals ; while 
 the branches in the second part go directly to muscles. 
 
 The internal maxillary vein is formed by the veins correspond- 
 
INFERIOR MAXILLARY NERVE. 103 
 
 ing to the branches of the artery. As the vein lies between the 
 PTERTGOID temporal and external pterygoid muscles it forms 
 
 PLEXUS OF VEINS. a plexus pterygoid plexus which communi- 
 cates, above, with the cavernous sinus by branches which come 
 through the foramina at the base of the skull ; in front it communi- 
 cates with the facial vein. It joins the temporal in the substance 
 of the parotid gland, and thus communicates with the external 
 jugular vein. 
 
 INFERIOR MAX- This great nerve is the largest of the three 
 ILLARY NERVE divisions of the fifth cerebral nerve. It differs 
 AND BRANCHES. from the other two divisions, i.e. the ophthalmic 
 and the superior maxillary, in that it contains motor as well as 
 sensory filaments ; the motor being furnished by the small non- 
 ganglionic root of the fifth nerve. It is necessary to remember this 
 point of its physiology, in order to understand its extensive dis- 
 tribution ; for the sensory portion supplies the parts to which it is 
 distributed with common sensation only, whilst the motor portion 
 supplies all the muscles concerned in mastication. 
 
 The nerve, then, composed of sensory 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 must be turned on one side to expose it. 
 Immediately after its exit from the skull, the nerve divides into 
 two parts, an anterior, or motor division, and a posterior or sen- 
 sory division. From the anterior portion (chiefly motor) are 
 derived branches distributed to the muscles of mastication. From 
 the posterior (mainly sensory) come the following branches : the 
 auriculo-temporal, gustatory, inferior dental and buccal ; there 
 are also motor branches to the mylo-hyoid and anterior belly 
 of the digastricus. This apparent anomaly will be presently 
 explained. 
 
104 INFERIOR MAXILLARY NERVE. 
 
 BRANCHES OF THE INFERIOR MAXILLARY NERVE. 
 
 SENSOET BRANCHES. MOTOK BRANCHES. 
 
 Auriculo-temporal. To temporal muscle. 
 
 Inferior dental. masseter. 
 
 Buccal. external pterygoid. 
 
 Gustatory or lingual. internal pterygoid. 
 
 mylo-hyoideus. 
 
 anterior belly of digastricus. 
 
 The branches to the temporal muscle, two in number, ante- 
 rior and posterior, pass 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, to the under 
 surface of the muscle. 
 
 The branch to the external pterygoid comes, apparently, from 
 the buccal nerve in its passage through this muscle. 
 
 The branch to the internal pterygoid muscle proceeds from 
 the inner side of the main trunk, close to the otic ganglion, and 
 descending between the internal pterygoid and the tensor palati, 
 enters the inner aspect of the muscle. 
 
 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 mainly 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 
 
INFERIOR MAXILLARY NERVE. 
 
 105 
 
 careful dissection, between it and the motor root of the third 
 division.* 
 
 The auriculo-temporal branch arises by two roots which em- 
 brace 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 
 
 FIG. 18. 
 
 PLAN OF THE BRANCHES OF THE INFERIOR MAXILLARY NERVE. 
 
 the condyle it sends filaments to the meatus auditorius, to the 
 gkin on the outer aspect of the ear, and to the articulation of the 
 jaw. It distributes also filaments to the parotid gland, and one 
 
 * Turner, ' On the Variation of the Buccal Nerve.' ' Journal of Anat. and Phys.,' 
 No. I. 1866. 
 
106 INFERIOB MAXILLAEY NERVE. 
 
 especially to the upper division of the facial, which endows it 
 with common sensibility : its branches have been described (p. 95). 
 The inferior dental branch emerges beneath the external ptery- 
 goid, and descends between the ramus and the internal 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 and furnishes filaments which ascend through the canals in 
 the fangs of the teeth to the pulp in their interior. Opposite the 
 foramen mentale it divides into two branches, the mental and 
 incisor. Observe that the same nerve which supplies the teeth 
 supplies the gums ; hence the sympathy between them. 
 
 a. 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 sheath of the inferior 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. 
 
 b. The dental branches pass upwards to the fangs of the molar and 
 bicuspid teeth. 
 
 c. The incisor branch is the continuation of the nerve, and passes to 
 the symphysis, supplying the canine and incisor teeth. 
 
 d. The mental branch (sometimes called labial) emerges through the 
 foramen mentale, and soon divides into numerous branches; some 
 ascend to the lower lip beneath the depressor labii inferioris, and com- 
 municate with the facial nerve ; others pass inwards to the skin of 
 the chin. 
 
 The gustatory or lingual nerve lies at first behind the external 
 pterygoid m., then descends obliquely forwards between the ramus 
 of the jaw and the internal pterygoid m., and subsequently for a 
 short distance between the jaw and the superior constrictor of the 
 pharynx. Here it lies close under the mucous membrane of the 
 mouth near the last molar tooth of the lower jaw. Division of 
 it in this situation has relieved pain in cancer of the tongue. The 
 gustatory n. then rests upon the stylo-glossus and the hyo-glossus 
 m., and after crossing Wharton's duct passes to the tip of the 
 tongue. 
 
INTERNAL LATERAL LIGAMENT. 107 
 
 The nerve at first lies in front of the inferior dental nerve 
 (with which it is frequently connected), and beneath the internal 
 maxillary a. Beneath the external pterygoid the gustatory n. is 
 joined at an acute angle by the chorda tympani (a branch of the 
 facial). This branch emerges through the Glaserian fissure, or 
 through a small canal by the side of it, and passing behind the 
 dental n., meets the gustatory, and runs along the lower border of 
 this nerve to join the submaxillary ganglion. It is eventually 
 distributed to the lingualis muscle. 
 
 The gustatory in its course gives off : 
 
 a. Communicating branches to the hypoglossal n., forming two or 
 more loops at the anterior border of the hyo-glossus. 
 
 b. Branches to the submaxillary ganglion. 
 
 c. Branches to the mucous membrane of the mouth, gums, and sub- 
 lingual gland. 
 
 d. Branches which pass to the papillae of the sides and tip of the 
 tongue : here also we find communications between this nerve and the 
 hypoglossal. 
 
 INTERNAL This so-called ligament (which is more like a 
 
 LATERAL LIGA- layer of fascia) passes from the spinous process 
 MKNTOFTHE o f the sphenoid bone to the inner side of the 
 
 foramen dentale. Between this ligament and the 
 neck of the jaw, we find the internal maxillary artery and vein, 
 the auriculo-temporal nerve, the middle meningeal artery, the 
 dental nerve and artery, and a portion of the parotid gland. 
 
 At this stage of the dissection you will be able to 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 carotids. 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 
 STYLO-GLOSSUS. j .-, , i MI T j 
 
 apex, 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 is a branch of the 
 hypoglossal. 
 
108 GLOSSO-PHARYNGEAL NERVE. 
 
 STYLO- This arises from the inner side of the styloid 
 
 PHABYNGEUS. process near the base, and is inserted into the 
 
 upper and posterior edges of the thyroid cartilage. It descends 
 along the side of the pharynx between the superior and the 
 middle constrictors. Curving round its lower border is seen the 
 glosso-pharyngeal nerve. Its nerve comes from the pharyngeal 
 plexus. Its action is to raise the 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 facial (p. 45), 
 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 
 forwards under the lower border of the stylo- 
 
 RYNGEAL NERVE. J 
 
 pharyngeus (p. 48). It is one of the divisions 
 of the eighth pair, arises by five or six filaments from the resti- 
 form tract of the medulla oblongata, leaves the skull through the 
 anterior part of the foramen jugulare in a separate sheath of 
 dura mater, in front of the remaining divisions of the eighth 
 pair, and descends between the internal jugular vein and the 
 internal carotid artery. It then crosses in front of the artery and 
 proceeds along the lower border of the stylo-pharyngeus. At this 
 point, it curves forwards over that muscle and the middle con- 
 strictor of the pharynx, and disappears beneath the hyo-glossus, 
 where it divides into its terminal branches, which supply the 
 mucous membrane of the pharynx, the back of the tongue, and the 
 tonsils. 
 
 The glosso-pharyngeal is regarded, at its origin, as purely a 
 sensory 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. 
 
INTERNAL CAROTID ARTERY. 109 
 
 composed of both sensory and motor filaments. At the base of 
 the skull it presents two ganglia the jugular and the petrous 
 (ganglion of Andersch). The branches given off by these ganglia 
 will be dissected hereafter ; at present the student can only 
 make out the branches which this nerve gives off in the neck, 
 namely : 
 
 Carotid branches, which surround the internal carotid artery, and 
 communicate with the pharyngeal branch of the pneumogastric and with 
 the sympathetic. 
 
 Pharyngeal branches, which form by the side of the middle constrictor 
 of the pharynx, a plexus, the pharyngeal plexus, supplemented by 
 filaments derived from the pneumogastric, the nervus accessorius, the 
 external laryngeal, and the sympathetic. Its branches supply the 
 constrictor muscles and the mucous membrane of the pharynx, the 
 back of the tongue, and the tonsils. 
 
 Muscular branches which enter the stylo-pharyngeus m. 
 
 Tonsillar branches which are given to the soft palate and the tonsils 
 forming a plexus (circulus tonsillaris). 
 
 Lingual branches, which are distributed to tbe base and lateral 
 aspects of tbe tongue. 
 
 The styloid process must now be cut through at its base, and 
 turned forwards with the muscles arising from it. The internal 
 carotid artery will thus be exposed in the cervical region, as far as 
 the carotid canal. The part of the artery contained within the 
 carotid canal will be described hereafter. 
 
 The internal carotid artery proceeds from the 
 CAEOTID AKTEBT. bifurcation of the common carotid at the upper 
 border of the thyroid cartilage, and ascends to the 
 base of the skull by the side of the pharynx, close to the trans- 
 verse processes of the three upper cervical vertebrae. It enters 
 the skull through the carotid canal in the temporal bone, runs 
 tortuously by the side of the body of the sphenoid, and terminates 
 in branches which supply the orbit and the brain. In the cervical 
 part of its course, it is situated immediately to the outer side of 
 the external carotid artery, behind the inner border of the sterno- 
 mastoid. It soon gets beneath the external carotid, and lies deeply 
 
110 PNEUMOGASTRIC NERVE. 
 
 seated by the side of the pharynx and tonsil. It lies upon the 
 rectus capitis anticus major, the superior laryngeal, sympathetic, 
 and pneumogastric nerves. It is crossed, successively, by the 
 hypoglossal nerve, the occipital artery, the digastricus and stylo- 
 hyoid muscles ; higher up it is crossed obliquely by the styloid 
 process, the stylo-glossus and stylo-pharyngeus muscles, by the 
 glosso-pharyngeal nerve, and the stylo-hyoid ligament, all of 
 which last-named structures intervene between it and the external 
 carotid. On the outer side of the artery is the internal jugular 
 vein ; and on the inner, the pharynx, the tonsil, and the ascending 
 pharyngeal artery. 
 
 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 
 tonsil. In opening an abscess, therefore, near the tonsil, 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 an undue deviation of the instrument in 
 an outward direction would injure the vessel. 
 
 ASCENDING This artery generally arises from the external 
 
 PHARYNGEAL carotid about half an inch above the angle of the 
 
 AETERY. common carotid. It ascends in a straight course 
 
 between the internal carotid artery and the side of the pharynx, 
 towards the base of the skull, resting upon the rectus capitis 
 anticus major. It gives off branches which supply the pharynx, 
 the tonsil, the Eustachian tube, and the muscles in front of the 
 spine. A very constant branch, the palatine, 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, another through the foramen jugulare 
 with the internal jugular vein. 
 
 PNHUMOGASTKIC The pneumogastric nerve is the largest and 
 
 NBRVB. longest of the three divisions of the eighth pair of 
 
PNEUMOGASTRIC NERVE. Ill 
 
 cerebral nerves. It arises from the medulla oblongata by a series 
 of roots, twelve to fifteen in number, along the restiform tract. 
 It passes out of the skull in a common sheath with the nervus 
 accessorius through the foramen jugulare. 
 
 Leaving the skull at the foramen jugulare, the nerve descends 
 in front of the cervical vertebra, 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 : 
 lower down, it lies 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 subcla- 
 vian vein, and then descending behind the right brachio-cephalic 
 vein 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 crosses in front 
 of the arch of the aorta, and behind the left bronchus to the 
 anterior part of the oesophagus. Both nerves subdivide on the 
 oesophagus into a plexus ; the right nerve forming the posterior 
 cesophageal plexus, the left the anterior. Each plexus again 
 collects its fibres together to form a single trunk : 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, the stomach, and the liver. 
 
 Within the foramen jugulare a small ganglion ganglion of 
 the root (Arnold's ganglion) is situated upon the pneumogastric 
 
 * The differences in the course and destination of the right and the left pneumo- 
 gastric nerves may be explained in the process of development. The student is 
 therefore referred to works which treat of this subject. 
 
112 PNEUMOGASTRIC NERVE. 
 
 nerve, and is joined by a branch from the nervus accessorius. 
 This ganglion will be described hereafter. About half an inch 
 below the preceding the pneumogastric nerve swells out, and forms 
 a second ganglion ganglion of the trunk (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 
 hypoglossal nerve, from which it receives filaments. It 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 connecting filaments 
 from these various branches, a compound nerve, and in all respects 
 analogous to a spinal nerve. 
 
 The branches of distribution of the pneumogastric are : 
 
 a. The auricular (Arnold), which cannot at present be seen, 
 will be made out in the dissection of the eighth pair at the base 
 of the skull. 
 
 6. The pharyngeal arises from the upper part of the ganglion 
 of the trunk, and descends either in front of or behind the inter- 
 nal carotid. The nerve, after passing the inner side of the internal 
 carotid, divides into branches, which with the other filaments 
 (described p. 109) upon the middle constrictor muscle form the 
 pharyngeal plexus. From this plexus branches are distributed 
 to the muscles and the mucous membrane of the pharynx. 
 
 c. The superior laryngeal, derived from the middle of the 
 ganglion of the trunk, descends behind the internal carotid, 
 and divides into two branches, the internal and the external 
 laryngeal. 
 
 The internal laryngeal passes to the interval between the os hyoides 
 and the thyroid cartilage, and enters the larynx (with the superior 
 laryngeal a.), through the thyro-hyoid membrane to be distributed to the 
 mucous membrane of the larynx and epiglottis. The external laryngeal, 
 the smaller, gives off some branches to the pharyngeal plexus and the 
 inferior constrictor, and then descends beneath the depressors of the os 
 hyoides to supply the crico-thyroid muscle. 
 
PNEUMOGASTRIC NERVE. 113 
 
 d. The cervical cardiac branches, upper and lower, descend 
 behind the sheath of the carotid artery to the cardiac plexus. The 
 upper branch is small and proceeds from the ganglion of the trunk ; 
 the lower comes from the trunk of the pneumogastric before it 
 enters the chest. Subsequently, the right lower cardiac nerve 
 descends with the innominate artery to join the deep cardiac plexus ; 
 the left passes over the arch of the aorta to join the superficial 
 cardiac plexus. 
 
 e. The inferior or recurrent laryngeal nerve turns, on the 
 right side, under the subclavian artery (p. 61), and ascends 
 obliquely inwards to the larynx behind the common carotid and 
 the inferior thyroid arteries : it lies subsequently behind the 
 trachea. On the left side, it tunas under the arch of the aorta, 
 just on the outer side of the remains of the 'ductus arteriosus;' 
 after which it runs up between the trachea and the oesophagus. On 
 both sides the nerves enter the larynx beneath the lower border 
 of the inferior constrictor, and supply all the intrinsic muscles 
 of the larynx, except the crico-thyroid. These nerves as they 
 turn under their respective vessels give off branches to the 
 deep cardiac plexus. 
 
 The remaining branches of the pneumogastric nerve to the 
 lungs, heart, oesophagus and stomach will be examined in the 
 dissection of the chest. 
 
 SPINAL ACCES- The spinal accessory nerve issues through the 
 SOKT NERVE. anterior part of the foramen jugulare, in a sheath 
 
 of dura mater common to it and the pneumogastric nerve. It 
 arises by numerous filaments from the medulla oblongata, below 
 the pneumogastric, and from the lateral column of the spinal 
 cord as low down as the sixth cervical vertebra. These roots con- 
 verge to the jugular foramen, where the nerve consists of two 
 portions : one of which, the internal or accessory, joins the 
 pneumogastric ; the other, the external or spinal, is distributed 
 to muscles. 
 
 The accessory part, within the foramen jugulare, sends one or 
 more filaments to the ganglion of the root of the pneumogastric. 
 It lies close to the pneumogastric nerve at the ganglion of the 
 
 i 
 
114 SYMPATHETIC NERVE IN THE NECK. 
 
 trunk, and is finally incorporated with the nerve below the 
 ganglion. 
 
 The spinal part separates from the accessory part below the 
 foramen jugulare. It then takes a curved course backwards and 
 outwards, lying in front of the transverse process of the atlas, 
 and, after supplying the sterno-mastoid muscle, is distributed to 
 the trapezius. 
 
 HYPOGLOSSAL This nerve passes through the anterior condy- 
 
 NERVE. i o j(j foramen in two fasciculi which join outside 
 
 the skull. The nerve comes forward between the internal jugu- 
 lar vein and the internal carotid artery, and then winds round 
 the occipital artery. Its further course has been described 
 (p. 49). 
 
 At the base of the skull it gives off several filaments which 
 connect it with the ganglion of the trunk of the pneumogastric 
 nerve. These two nerves are sometimes almost inseparably 
 united. It gives off also several delicate filaments to the superior 
 cervical ganglion of the sympathetic, and communicates with 
 the loop formed by the first two spinal nerves in front of the 
 atlas. 
 
 SYMPATHETIC Now examine the cervical ganglia of the sym- 
 
 NKHVE. pathetic system of nerves. This ' system ' consists 
 
 of a series of ganglia arranged on each side of the spine, from the 
 first cervical to tne last sacral vertebra. The successive ganglia 
 of the same side are connected by intermediate nerves, so as to form 
 a continuous 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 enters 
 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 impar, situated in the 
 mesial line, upon the coccyx. 
 
 * Here is situated the so-called ganglion of Ribes. 
 
SYMPATHETIC NERVE IN THE NECK. 115 
 
 The ganglia, as already stated, are connected with the spinal 
 nerves ; this connection takes place by two filaments one of 
 white nerve-fibre which passes from the spinal nerve to the 
 ganglion, the other, of grey, from the ganglion to the spinal 
 nerve. 
 
 The different portions of the sympathetic gangliated cord 
 receive, respectively, the distinguishing names of the cervical, 
 dorsal, lumbar, and sacral. At present we have only to consider 
 the cervical portion of it. 
 
 To expose the cervical portion of the sympathetic, the internal 
 carotid artery, the pneumogastric, glosso-pharyngeal, and hypo- 
 glossal nerves should be cut through near the base of the skull ; 
 then by careful dissection the superior cervical ganglion can be 
 traced out. 
 
 CERVICAL GAN- ^ n t ne cervical portion of the sympathetic are 
 GLIA OF SYMPA- three ganglia, named from their position, superior, 
 THETIC. middle, and inferior. 
 
 The superior cervical ganglion, the largest of the three, is 
 situated near the base of the skull, opposite the second and 
 third cervical vertebrae, and lies behind and on the inner side of 
 the internal carotid artery, upon the rectus capitis anticus major. 
 It is of a reddish-grey colour like the other ganglia, of an elongated 
 oval shape, varying in length from one to two inches. To facili- 
 tate 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. 
 
 b. With the hypoglossal, with both ganglia of the pneumogastric, and 
 with the glosso-pharyngeal. 
 
 c. Its important cranial branch runs with the internal carotid a. into 
 the carotid canal of the temporal bone, and there divides into two, an 
 outer and an inner. Now this outer branch accompanies the artery 
 through its bony canal, ramifies upon it by the side of the body of the 
 sphenoid, and so constitutes the ' CAROTID PLEXUS.' From this outer 
 branch a filament proceeds to the Gasserian ganglion, another to the sixth 
 
 i 2 
 
116 SYMPATHETIC NERVE IN THE NECK. 
 
 cranial nerve ; a third joins the great petrosal branch of the facial, and 
 forms the Vidian nerve. The inner branch, running on with the artery 
 to the cavernous sinus, there forms another plexus, called from its posi- 
 tion the ' CAVERNOUS PLEXUS.' Here the sympathetic is seen to com- 
 municate with the third, the fourth, and the ophthalmic branch of the 
 fifth cranial n. Lastly, from both these plexuses secondary plexuses 
 proceed, of which the minute filaments ramify on, and supply the coats 
 of, the terminal branches of the internal carotid. 
 
 d. With the several ganglia of the sympathetic system about the 
 head and neck ; namely, the ophthalmic, spheno-palatine, otic, and sub- 
 maxillary. 
 
 The branches which it distributes are 
 
 e. Nerves to the Heart. One or more (superior cardiac) descend 
 behind the sheath of the carotid in front of the inferior thyroid artery and 
 recurrent laryngeal nerve, and, entering the chest, join the superficial and 
 deep cardiac plexuses. 
 
 f. 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 slieath, 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, and join the external and recurrent laryngeal nerves. 
 
 b. Branch to the Heart. This (middle cardiac) nerve usually de- 
 scends, on the right side, in front of the subclavian artery into the chest, 
 where it lies on the trachea. It is joined by some cardiac filaments from 
 the recurrent laryngeal nerve, and joins the deep cardiac plexus. On 
 the left side, this cardiac nerve lies between the carotid and subclavian 
 arteries. 
 
 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. 
 
SYMPATHETIC NERVE IN THE NECK. 117 
 
 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 vertebra, form a plexus around the 
 vertebral artery. 
 
 The branches which it gives off are 
 
 a. Inferior Cardiac Nerve. This communicates with the recurrent 
 laryngeal and middle cardiac nerves, and joins the cardiac plexus beneath 
 the arch of the aorta. 
 
 b. Nerves to the Blood-vessels. These ramify around the vertebral 
 and subclavian arteries. 
 
118 
 
 DISSECTION OF THE THORAX. 
 
 BEFORE the several organs contained in the thorax are examined, 
 the student should have some knowledge of its framework. The 
 true ribs with their cartilages describe a series of arcs increasing 
 in length from above downwards, and form, with the dorsal ver- 
 tebrae behind, and the sternum in front, a barrel of a conical shape, 
 broader in the lateral than in the antero-posterior diameter. The 
 base is closed in the recent state by a muscle, the diaphragm, 
 which forms a muscular partition between the chest and the 
 abdomen. This partition is arched upwards, so that it constitutes a 
 vaulted floor for the chest, and by its capability of alternately falling 
 and rising, it increases and diminishes the capacity of the thorax. 
 The spaces between the ribs are occupied 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. 
 
 Such, in outline, is the framework of the thorax, which con- 
 tains the heart with its large vessels and the lungs. Its walls are 
 composed of different structures bone, cartilage, muscles and 
 ligaments, which fulfil two important conditions : 1st, by their 
 solidity and elasticity they protect the important organs contained 
 in the thorax ; 2ndly, by their alternate expansion and contraction 
 they act as mechanical powers of respiration. For they can in- 
 crease the capacity of the chest in three directions : in height, by 
 the descent of the diaphragm ; in width, by the rotation of the 
 ribs ; and in depth, by the elevation of the sternum. 
 
 BOUNDARIES OF The upper opening of the osseous thorax is 
 THE THORAX. bounded posteriorly by the body of the first dorsal 
 
DISSECTION OF THE THORAX. 119 
 
 vertebra, laterally by the first ribs, and in front by the upper 
 border of the manubrium sterni. The aperture gives passage to 
 the trachea, the oesophagus, the large vessels of the head and neck 
 and upper extremities, viz., the innominate, the left carotid and 
 subclavian arteries, with the left innominate and right subclavian 
 and internal jugular veins, the superior intercostal and internal 
 mammary arteries, the middle thyroid veins, the sterno-hyoid, 
 sterno-thyroid and longus colli muscles, the pneumogastric, the 
 left recurrent laryngeal, the phrenic and the sympathetic nerves ; 
 the cardiac branches of the sympathetic, and the cardiac branches 
 of the pneumogastric ; also to the first dorsal nerve as it passes 
 up to join the brachial plexus, the thoracic duct, the thymus gland 
 (in early life), and lastly to the apices of the lungs, which, with 
 their pleural coverings, rise up on each side into the neck for about 
 one inch and a half above the first rib ; the interspaces between 
 these various structures being occupied by a dense fibro-cellular 
 tissue. 
 
 The base of the thorax, formed by the diaphragm, descends in 
 front (in the dead subject) on the right side as low as the upper 
 border of the fifth rib ; on the left as low as the upper border of the 
 sixth rib.* 
 
 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 moveable, and therefore permit a greater 
 
 * That the student may have some knowledge of the diameters of the chest at dif- 
 ferent situations, the following measurements have been taken from a well-articulated 
 male skeleton of the average height: The antero-posterior diameter at the upper 
 opening of the thorax is 2 inches, at the articulation of the manubrium with the 
 gladiolus it is 4^ inches, and at the junction of the gladiolus with the ensiform carti- 
 lage it has increased to 5| inches. The transverse diameter of the upper opening 
 was found to be 4f inches; between the second ribs, 7 inches; between the third, 
 8 inches; the diameter increases in regular proportion as far as the ninth rib, where it 
 attains a measurement of I0f inches; below this it gradually decreases. The articula- 
 tion of the manubrium and the gladiolus is on a level with the fourth dorsal vertebra ; 
 the junction of the ensiform cartilage with the gladiolus is on a level with the border of 
 the ninth or tenth dorsal vertebra; and, lastly, the upper border of the manubrium, 
 corresponds to the second dorsal vertebra. 
 
120 DISSECTION OP THE THORAX. 
 
 enlargement of the chest at its upper part, in adaptation to the 
 condition of the abdomen during pregnancy. 
 
 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 side the 
 internal mammary artery should be dissected ; on the other, re- 
 moved. 
 
 In the dissection of the chest let us take the parts in the 
 following order : 
 
 1. Trmngularis sterni, with the internal mammary artery. 
 
 2. Mediastina, anterior, middle, and posterior. 
 
 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. 
 l'4. Nerves of the heart ; cardiac plexuses. 
 
 TBIANGUIAKIS On the under surface of the sternum and carti- 
 
 STEKNI. lages of the ribs is a thin flat muscle, named the 
 
 triangularis sterni. It arises from the ensiform cartilage, the 
 lower part of the sternum, and the cartilages of one or t'wo lower 
 true ribs, and is inserted by digitations into the cartilages of the 
 true ribs from the sixth to the second : its fibres ascend outwards 
 to their insertion. This muscle is evidently a continuation up- 
 wards of the anterior portion of the transversalis abdominis. Its 
 
 * Those who are more proficient in dissection should not remove the whole of the 
 sternum, but leave a quarter of an inch of its upper part with the first rib attached to 
 it. This portion serves as a valuable landmark, although it obstructs, to a certain ex- 
 tent, the view of the subjacent vessels. 
 
DISSECTION OP THE THOEAX. 121 
 
 action is to depress the costal cartilages, and thus, on emergency, it 
 acts in expiration. Its nerves come from the intercostal nerves, 
 its arteries from the internal mammary. 
 
 INTERNAL MAM- This artery is given off from the subclavian in 
 MARY ARTERY. the first part of its course. On entering the chest 
 it lies between the cartilage of the first rib and the pleura and is 
 crossed by the phrenic nerve. It then descends perpendicularly, 
 about half an inch from the sternum, between the cartilages 
 of the ribs and the triangularis sterni, as far as the seventh 
 costal cartilage, where it divides into two branches, the inusculo- 
 phrenic and the superior epigastric. The latter branch then 
 enters the wall of the abdomen behind the rectus abdominis, 
 and finally inosculates with the epigastric (a branch of the 
 external iliac). The branches of the internal mammary are as 
 follows : 
 
 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 thymic. These branches supply the cellular 
 tissue of the anterior mediastinum, the pericardium, and the triangularis 
 sterni. The thymic are only visible in childhood, and disappear with the 
 thymus gland. 
 
 c. Anterior intercostal. Two for each intercostal 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, to 
 supply the mammary gland. 
 
 e. The mvsculo-phrenic branch runs outwards behind the cartilages 
 of the false ribs, and terminates near the last intercostal space. It sup- 
 plies small branches to the diaphragm, to the sixth, seventh, and 
 sometimes the eighth intercostal spaces. 
 
 Two venae comites accompany the artery, and form a single 
 
122 
 
 DISSECTION OF THE THORAX. 
 
 trunk at the upper part of the chest, which terminates in the 
 brachio-cephalic vein of its own side. 
 
 LYMPHATIC There are several lymphatic glands in the 
 
 GLANDS. neighbourhood of the internal mammary artery. 
 
 They receive the lymphatics from the inner portion of the mam- 
 mary gland, from the diaphragm, and the upper part of the abdo- 
 minal wall. In disease of the inner portion of the mamma, these 
 glands may enlarge without any enlargement of those in the 
 axilla. 
 
 If a transverse section were made through the chest (see fig. 
 20), you would observe that as the pleurae nowhere come into 
 actual contact, a space is left between them extending from the 
 sternum to the spine, and which is larger in the middle than in 
 front or behind. This interval is called by anatomists the 
 interpleural space, and for convenience sake is subdivided into 
 an anterior, middle, and posterior mediastinum. 
 
 MEDIASTINA, The mvdiastina are the spaces which the two 
 
 ANTEEIOE, MIDDLE pleural sacs leave between them in the antero- 
 AND POSTERIOR. posterior plane of the chest. There is an anterior, 
 a middle, and a posterior mediastinum. To put these spaces in 
 the simplest light, let us imagine the heart and lungs to be re- 
 moved from the chest, and the two pleura! sacs to be left in it by 
 themselves. The two sacs, if inflated, would then appear like two 
 FIG. 19. bladders, in contact only in the 
 
 middle, as shown by the dotted 
 outlines in the annexed scheme 
 (fig. 19). The interval marked a, 
 behind the sternum, would repre- 
 sent the anterior mediastinum ; 
 th interval 6, the posterior medi- 
 astinum. Now let us introduce 
 the heart again, between the 
 two pleural sacs : these must 
 give way to make room for it, 
 so that the two sacs are largely 
 separated in the middle line of the chest; and the space thus 
 
DISSECTION OF THE THOEAX. 
 
 123 
 
 occupied by the heart and large vessels takes the name of the 
 middle mediastinum. 
 
 Looking at the chest in front, the anterior mediastinum ap- 
 pears as shown in the diagram (p. 125). It is not precisely ver- 
 tical in its direction, for it 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. Poste- 
 riorly it is limited by the pericardium covering the heart, aorta 
 and its branches, and the pulmonary artery. 
 
 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) 
 a few lymphatic glands, and the left internal mammary artery and. 
 veins. 
 
 I'IG. 20. 
 
 Internal mam- 
 mary a. 
 
 Phrenic n. 
 
 Internal mam- 
 mary a. 
 
 Phrenic n. 
 
 (Esophagus with 
 pneumogastric n. 
 i Aorta. 
 
 _ Thoracic duct. 
 _ Vena azygos. 
 
 DIAGRAM OF THE REFLECTIONS OF THE PLEtJRAL SACS IN DOTTED LINES. 
 
 The posterior mediastinum (fig. 20) contains the oesophagus, 
 the two pneumogastric nerves, the aorta, the thoracic duct, the 
 vena azygos, the trachea, and some lymphatic glands. 
 
124 DISSECTION OF THE THORAX. 
 
 The middle mediastinum is the largest of the mediastina, and 
 contains the heart with its large vessels and the phrenic nerves. 
 
 Before passing to the dissection of the contents of the thorax, 
 the student should carefully trace the outline of the free borders 
 of the pleurae as seen in the front of the chest. As the margins of 
 the lungs for all practical purposes correspond with the borders of 
 the pleurae, we shall confine our description to the more important 
 of the two structures, viz. the lungs. The value of this investiga- 
 tion is, that we are enabled to trace upon a living chest the 
 outlines of the lungs, and know what parts are naturally resonant 
 on percussion. 
 
 Commencing from above (fig. 21, p. 125) we find that the apex 
 of the lung extends into the neck, from an inch to an inch and a 
 half above the clavicle. This part of the lung ascends behind the 
 subclavian artery and the scalenus anticus 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 middle line, where their borders nearly 
 meet opposite the junction of the second rib. There is thus little 
 or no lung behind the manubrium sterni. 
 
 From the level of the second costal cartilage to the level of the 
 fourth, the inner margins of each lung run nearly parallel and 
 almost in contact behind the middle of the sternum ; consequently 
 they overlap 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 follows nearly 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 like a little 
 tongue. The riyht 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. Hypertrophy of the heart, or effusion into the peri- 
 cardium, will not only raise the point where the lungs diverge 
 above the ordinary level, but also increase their divergence ; hence 
 the greater dulness on percussion. 
 
POSITION OF THE HEAET. 125 
 
 The prcecordial region is the outline of the* 
 EEGION. heart traced upon the front wall of the chest. It 
 
 is important for auscultatory purposes that we should know how 
 much of the heart is covered and separated from the wall of the 
 chest by intervening lung (fig. 21). The following will give a fair 
 
 FIG. 21. 
 
 FORM OF THE LUNGS, AND THE EXTENT TO WHICH THEY OVERLAP THE HEART AND 
 
 ITS VALVES. 
 
 indication. ' Let the middle of the fifth costal cartilage be the 
 centre of a circle two inches in diameter ; this circle will define, for 
 all practical purposes, that part of the praecordial region which is 
 naturally less resonant to percussion ; here the heart is uncovered 
 except by pericardium and loose cellular tissue, and lies close 
 
126 BRACHIO-CEPHALIC VEINS. 
 
 behind the thoracic wall. In the rest of the praecordial region 
 the heart is covered and separated from the chest wall by inter- 
 vening lung.' 
 
 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. 21, p. 125). They are all covered by a thin portion of lung; 
 for this reason we ask a patient to stop breathing while we listen to 
 his heart. 
 
 Before we can display the brachio-cephalic veins, the layer of 
 the deep cervical fascia must be removed which descends over 
 them from the neck and is lost upon the pericardium. Their 
 coats are intimately connected with this fascia; and one of its 
 functions appears to be to keep the veins permanently open for 
 the free return of blood to the heart. 
 
 BRACHIO- The right and left brachio-cephalic (innomi- 
 
 CEPHALIC VEINS. nate) veins are formed, near the sternal end of 
 the clavicle, by the confluence of the internal jugular and subclavian 
 veins. They differ in their course and relations, and must, there- 
 fore, be described separately. 
 
 The left brachio-cephalic vein passes obliquely behind the 
 first bone of the sternum, the sterno-hyoid and thyroid muscles, 
 towards the right side, to assist in forming the vena cava superior 
 (fig. 22). It is about two and a half inches in length, and its direc- 
 tion 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 aneurysm of these vessels 
 for what happens ? The vein becomes compressed between the 
 aneurysm and the sternum ; hence the swelling and venous con- 
 gestion of the parts from which it returns its blood ; namely, of 
 the left arm, and the left side of the neck. The upper border of 
 the vein is not far from the upper border of the sternum : in some 
 cases it lies even higher, and we have seen it crossing in front of 
 the trachea fully an inch above the sternum. This occasional 
 
VENA CAVA SUPERIOR. 
 
 127 
 
 deviation should be borne in mind in the performance of tra- 
 cheotomy. 
 
 The right brachio-cephalic vein descends nearly vertically to 
 join the superior vena cava, opposite the first right intercostal 
 space. It is about an inch and a half 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 generally empty themselves into the 
 right and left brachio-cephalic are as follows : 
 
 The EIGHT B. C. Vein receives : 
 
 The vertebral. 
 
 The deep cervical (not drawn). 
 
 The internal mammary. 
 
 The middle thyroid (sometimes). 
 
 The LEFT B. C. Vein receives :- 
 
 The vertebral. 
 
 The deep cervical (not drawn). 
 
 The internal mammary. 
 
 The middle thyroid. 
 
 The superior intercostal. 
 
 The pericardiac. 
 
 FIG. 22. 
 
 Vena azygos 
 
 Superior intercostal 
 Internal mammary . . 
 
 Inferior thyroid. 
 
 Internal jugular. 
 External jugular. 
 --Vertebral. 
 
 ~ Supra-scapular. 
 ' Posterior scapular. 
 |- Subclavian. 
 
 Internal mammary. 
 Pericardiac. 
 
 Superior inter- 
 costal. 
 
 SUPERIOR VENA CAVA AND ITS TRIBUTARIES. 
 
 This is the great vein through which the im- 
 pure blood from the head, upper extremities, and 
 chest, returns into the right auricle. It is formed by the junction 
 
 VKNA CAVA 
 SUPKRIOR. 
 
128 ARCH OF THE AORTA. 
 
 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. The vena cava descends 
 vertically, with a slight inclination backwards, to the upper 
 and anterior 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 how 
 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 ves- 
 sels ; and that it is overlapped by the ascending aorta, which 
 lies to its left side. 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 opens into it after hooking over 
 the right bronchus. 
 
 The aorta is the great trunk from which all 
 COURSE AND & 
 
 RELATIONS or THE the arteries of the body carrying arterial blood are 
 ARCH OF THE derived. It arises from the upper and back part 
 
 AORTA. o f ^ e i e ft ventricle of the heart. Its origin is 
 
 situated behind the pulmonary artery and on the left side of the 
 sternum, about the level of the lower border of the third costal 
 cartilage. It ascends forwards and to the right as high as the 
 lower border of 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 at the lower border of the fourth vertebra. 
 The direction of the arch, therefore, is from the sternum to the 
 spine, and rather obliquely from right to left. 
 
 The arch of the aorta presents partial dilatations in certain 
 situations. One of these, called the great sinus 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 
 
AECH OF THE AOETA. 129 
 
 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 enclosed 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, 
 where it lies almost in contact with the sternum. Its commence- 
 ment is covered by the pulmonary artery, and overlapped by the 
 appendix of the right auricle. On its right side, 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 right 
 auricle, the right pulmonary artery and vein and the right bron- 
 chus. 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, the left pneumogastric, 
 the superficial cardiac nerves, and the pericardiac veins. 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 arte- 
 riosus. The artery rests upon the trachea (a little above its bifur- 
 cation), the deep cardiac plexus, the oesophagus, the thoracic duct, 
 and the left recurrent laryngeal nerve. From the transverse part 
 of the arch arise the arteria innominata, the left carotid, and the 
 left subclavian arteries. 
 
 Descending portion. This part of the arch lies upon the left 
 side of the body of the third dorsal vertebra, and at the lower 
 border of the body of the fourth dorsal it takes the name of the 
 
 K 
 
130 BRACHIO-CEPHALIC ARTERY. 
 
 descending thoracic aorta. On its right side are the ossophagus 
 and thoracic duct ; on its left is the pleura ; in front is the root of 
 the left lung. 
 
 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 superficial 
 cardiac plexus of nerves. 
 
 RELATIONS OF These relations vary according to the size of the 
 
 THE AHCH OF THE heart, the obliquity of the ribs, and the general 
 AOETA TO THE development of the chest. In a well-formed adult 
 STERNUM. ^ ascen( ji n g aorta is, at the most prominent part 
 
 of its bulge, about half 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.* 
 
 From the upper part of the arch arise three large arteries for 
 the head, neck, and upper limbs ; namely, the brachio-cephalic or 
 innominate artery, the left carotid, and the left subclavian. 
 
 BEACHIO-CEPHA- This, the largest of the three, arises from the 
 LIC OK INNOMINATE commencement of the transverse part of the arch. 
 AKTEBY. j^ asc ends obliquely towards the right, and after a 
 
 course of about one inch and a half to two inches divides behind 
 the right sterno-clavicular joint into two arteries of nearly equal 
 size the right subclavian and the right carotid. 
 
 The relations of the b. c. artery are as follow. It lies behind 
 the first bone (manubrium) of the sternum and the right sterno- 
 clavicular joint. It ascends obliquely (towards the right) in front 
 of and close to the trachea. On its right side, and close to it, is 
 the right b. c. vein. On its left is the left carotid a. In front of 
 it are the left b. c. vein, the sterno-hyoid and sterno-thyroid m. 
 
 * 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, we 
 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 
 second costal articulation. The highest part of the arch was on a level with the upper 
 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. 
 
LEFT CAEOTID AETEEY. 131 
 
 Parallel with, and close to, the artery are the slender cardiac 
 nerves.* 
 
 With the anatomy of the parts before you, you can under- 
 stand that an aneurysm of the innominate artery might be distin- 
 guished from an aneurysm of the aorta 1. 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 
 aneurysmal thrill being confined to the right arm.f 
 
 LEFT CAEOTID This artery arises from the arch of the aorta 
 
 ABTEBY. close to, and to the left of, the arteria innominata. 
 
 It ascends obliquely behind the first bone of the sternum, and the 
 sterno-hyoid and thyroid muscles, 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 
 ossophagus and thoracic duct. It is crossed by the left brachio- 
 cephalic vein ; on its left side are the left subclavian artery and 
 pneumogastric nerve ; on the right side is the arteria innomi- 
 nata. In the rest of its course it resembles the right carotid 
 (p. 32). 
 
 LiFrSuBCLA- This is the third branch of the arch. It 
 
 TIAN ABTEBY. ascends nearly vertically out of the chest to the 
 
 inner border of the first rib, and then curves outwards behind the 
 scalenus anticus. In the first part of its course it is deeply seated, 
 and is covered on its left side by the pleura. Close to its right 
 side are ,the left carotid, the trachea and oesophagus ; between the 
 
 * 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. 37), which ascends in 
 fronfc of the trachea to the thyroid body, and is therefore directly in the way in 
 tracheotomy. 
 
 f If the innominate artery be ligatured, the circulation would be maintained by the 
 following collateral branches: 1. Between the branches of the two external carotids, 
 which anastomose across the middle line. 2. Between the aortic intercostal and the 
 superior intercostal. 3. Between the aortic intercostals and the internal mammarj, 
 long thoracic, alar thoracic, and subscapular arteries. 4. Between the internal 
 mammary and deep epigastric. 5. Between the inferior thyroid arteries. 6. Between 
 the two vertebrals. 7- Between the two internal carotid arteries. 
 
 x 2 
 
132 PHRENIC NERVES. 
 
 artery and the oesophagus is 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. Anterior to the artery also are the pneumo- 
 gastric, the phrenic, and the cardiac nerves. 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. 62). 
 
 COUBSE OF THE The phrenic nerve comes from the third, fourth 
 PHRENIC NEBVES and fifth cervical nerves. It descends over the 
 THROUGH THK scalenus anticus, and enters the chest between 
 
 the subclavian vein and artery. It then crosses 
 over the internal mammary artery and runs in front of the root of 
 the lung between the pleura and the pericardium to the diaphragm 
 (fig. 23), to the under surface of which it is distributed.* 
 
 The phrenic nerve is joined on the scalenus anticus by an 
 offset from the fifth cervical branch of the brachial plexus ; by 
 another filament from the sympathetic nerve ; and very frequently 
 by a small loop from the nerve to the subclavius muscle ; occa- 
 sionally also by a branch from the descendens noni. 
 
 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, since it curves over 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 symptoms are likely to be produced by an aneurysm of the 
 arch of the aorta, or any of the primary branches. A glance at the 
 important parts in the neighbourhood helps to answer the question. 
 The effects will vary according to the part of the artery which 
 
 * In the Museum of the College of Surgeons there is a dissection showing that the 
 right phrenic nerve enters the diaphragm close to the right side of the vena cava 
 inferior, while the left phrenic enters the left muscle of the diaphragm. 
 
PHRENIC NERVES. 
 
 133 
 
 is the seat of the aneurysm, and according to the size, the form, 
 and the position of the tumour. One can understand that com- 
 pression of the vena cava superior, or either of the brachio-cephalic 
 
 FIG. 23. 
 
 3rd cervical n. 
 
 4th cervical n. 
 Pncumogas- 
 tric n. . . 
 
 5th cervical n. 
 
 
 Brachial plexus 
 
 Phrenic n. . . 
 
 Line of reflec- 
 tion of peri- 
 cardium. 
 
 Cervicalis ascendens a. 
 Scalenus anticus. 
 Inferior thyroid a. 
 
 Snperficinlis 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. 
 
 veins, would occasion congestion and cedema of the parts from 
 which they return the blood ; that compression of the trachea 
 or one of the bronchi might occasion dyspnoea, and thus simulate 
 
134 POSITION OF THE HEAET. 
 
 disease of the larynx ; * that compression of the cesophagus would 
 give rise to symptoms of obstruction. Nor must we forget the 
 immediate 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 ? 
 
 Thus you can understand how aneurysms of the aorta may 
 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 aneurysm 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. If an aneurysm 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, the heart is prevented from acting. 
 
 POSITION AND The heart is situated obliquely in the chest, 
 
 FORM or THE between the lungs. Its base, i.e. the part by 
 
 HEART. which it is attached, 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 cartilages. It is supported, towards the abdomen, by the 
 tendinous centre of the diaphragm. It is maintained in its posi- 
 tion by a membranous bag termed the pericardium, which is lined 
 by a serous membrane to facilitate its movements. The pericar- 
 dium must first claim our attention. 
 
 The pericardium is the membranous bag which 
 
 encloses the heart and the large vessels at its base. 
 
 It is broadest below, where it is attached to the tendinous centre 
 
 of the diaphragm, and to the muscular part in connection with 
 
 * 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. Gaz.,' Dec. 22nd, 1843. A case in which loss of voice was produced 
 by the pressure of an aneurysmal tumour upon the left recurrent nerve. 
 
POSITION OP THE HEART. 135 
 
 the tendon ; above, it is prolonged over the great vessels of the 
 heart, and is connected with the deep cervical fascia. On each side, 
 
 FIG. 24. 
 
 EELATIVB 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 wtlws 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 is in contact with the pleura ; the phrenic nerve running down 
 between them. In front of it, is the anterior mediastinum ; behind 
 
136 PERICARDIUM. 
 
 it, is the posterior. Of the objects in the posterior mediastinum, 
 that which is nearest to the pericardium is the oesophagus. It 
 should be remembered that the oesophagus is in close contact with 
 the back of the pericardium and left auricle for nearly two inches ; 
 this fact accounts for what is sometimes observed in cases of 
 pericarditis where there is much effusion ; namely, pain and 
 difficulty in swallowing. 
 
 The pericardium is a fibro-serous membrane. Its fibrous layer, 
 which constitutes its chief strength, is external. This layer is 
 attached, below, to the central tendon and the adjoining muscular 
 part of the diaphragm. Above, it forms eight sheaths for the great 
 vessels at the base of the heart ; namely, one for the vena cava 
 superior, four for the pulmonary veins, two for the pulmonary 
 arteries, and one for the aorta. The serous layer forms a shut sac. 
 It lines the fibrous layer to which it is intimately attached, 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 front of the vena cava superior. 
 
 The serous layer of the pericardium covers the large vessels to 
 an extent greater than is generally imagined ; though the extent is 
 not precisely similar in all bodies. The aorta and pulmonary artery 
 are enclosed 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, through 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 the auricles, is covered by the serous pericardium. 
 The superior cava is covered all round, except behind, where it 
 crosses the right pulmonary artery. The inferior cava within the 
 pericardium is partly covered in front. 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 
 
PR^ECORDIAL REGION. 137 
 
 connected to the left bronchus. The object of these serous reflec- 
 tions is to facilitate the free action of the heart and the great 
 vessels at its base. 
 
 In the healthy state, the capacity of the pericardium 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 pericardium is 
 not extensile. When an aneurysm bursts into it, death 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 oesophageal arteries. 
 
 On separating the left pulmonary artery and pulmonary vein, 
 you will notice a fold of serous membrane about three-quarters of 
 an inch long and about one inch in depth : this is the vestigial 
 fold of the pericardium, described by Marshall.* It passes 
 from the side of the left auricle to the left superior intercostal 
 vein. It is a vestige of the left v. c. superior which exists in 
 foetal life. 
 
 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. 
 
 POSITIOK OF The heart then, placed behind the lower half 
 
 THB HEART of the sternum, occupies more of the left than the 
 
 CONTINUED. right half of the chest, and rests upon the ten- 
 
 dinous centre of the diaphragm, which is a little below 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 
 * 'Philosoph. Transactions,' 1850. 
 
138 PR^ECORDIAL REGION. 
 
 and sixth ribs, about two inches below the nipple and an inch to 
 its sternal side. Speaking broadly, the base corresponds with a 
 line drawn across the sternum along the upper borders of the third 
 costal cartilages. The right border of the heart is formed almost 
 entirely by the free margin of the right auricle, and, when dis- 
 tended, bulges nearly an inch to the right of the sternum. The 
 left border of the heart is formed by the round border of the left 
 ventricle, and reaches from a point, commencing at the second 
 left intercostal space, to a point placed two inches below the 
 nipple and an inch to its sternal side. The horizontal border is 
 formed by the sharp margin of the right ventricle, and extends 
 from the sternal attachment of the fifth right costal cartilage, to 
 meet the lowest point of the left margin. 
 
 The normal position which the cardiac valves hold to the 
 thoracic walls is difficult to define with precision, and this probably 
 accounts for the discrepancies noticed in anatomical works on 
 this subject. The following relations are the results of care- 
 fully made observations in the * post-mortem ' room : The right 
 auricula-ventricular valves are situated behind the sternum about 
 the level of the fourth costal cartilage : the left auriculo-ventri- 
 cular valves are opposite the third intercostal space, about one 
 inch to the left of the sternum ; the cusps of these valves extend 
 as low as the fifth costal cartilage. The pulmonary valves lie 
 immediately behind the junction of the third left costal cartilage 
 with the sternum ; the aortic valves are behind the upper 
 border of the third intercostal space just at the left side of the 
 sternum. 
 
 The position of the heart varies a little with the position of the 
 body. Of this anyone may convince himself by leaning alter- 
 nately forwards and backwards, by lying on this side and on that, 
 placing at the same time his hand upon the prsecordial region. 
 He will find that he can, in a slight degree, alter the place and the 
 extent 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. 
 
PLEURA. 139 
 
 As the lungs are continually gliding to and fro, 
 
 PLEURA 
 
 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, like all other serous sacs, has a parietal 
 and a visceral layer ; that is, one part of the sac lines the contain- 
 ing 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 
 covers the lung, pleura pulmonalis. Unlike the peritoneum, the 
 pleura forms no folds except a small one called ligamentum 
 latum pulmonis, which extends from the root of the lung to the 
 diaphragm. 
 
 The pleural sac (fig. 20, p. 123) lines the ribs and part of the 
 sternum ; from the sternum it is reflected backwards over the peri- 
 cardium ; 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 and the diaphragm. 
 
 The thickness of the pleura differs ; on the lung it is thin, 
 semi-transparent, and firmly adherent ; on the ribs and diaphragm 
 it is thick, and may be easily separated from its osseous and 
 muscular connections. 
 
 The spaces called anterior and posterior mediastina, formed 
 by the separation of the pleura?, have been already described, 
 p. 123. 
 
 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 ; when by air, pneumo-thorax ; when by 
 blood, haemo-thorax. 
 
 * The pleura costalis is covered with flattened epithelial cells ; the pleura pul- 
 monalis with polyhedral granular cells. (Klein.) 
 
140 THE LUNGS. 
 
 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 
 lower border of the last rib. Supposing a ball to lodge in the 
 pleural sac, it might 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 The lungs are situated in the chest, one on each 
 
 FOKM OF THE side of the heart. Each fits accurately into the 
 
 LUNGS, cavity which contains it. Each, therefore, is co- 
 
 nical in form ; the base rests on the diaphragm ; the apex projects 
 into the root of 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. 
 The best way to see the shape of the lungs is to inject them through 
 the trachea with wax, which is tantamount to taking a cast of each 
 thoracic cavity. In such a preparation, besides the general con- 
 vexities 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 and forwards to the junc- 
 tion of the 6th rib with its cartilage (fig. 21). Speaking broadly, 
 nearly the whole of the anterior portion of the lung is formed by 
 the upper lobe ; nearly 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 marks off, 
 from its lower part, a triangular portion called its 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 
 
CONTENTS OF POSTERIOE MEDIASTINUM. 141 
 
 by the liver. On an average, the right lung weighs 24 ounces ; 
 the left 21 ounces. 
 
 POSTERIOR The posterior mediastinum (p. 123) is formed 
 
 MEDIASTINUM AND by the reflection of the pleural sac on each side, 
 ITS CONTENTS. from the root of the limg to the sideg of the bodieg 
 
 of the dorsal vertebrse. 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 descending thoracic 
 aorta ; in front of the aorta, the cesopha,gus, with the pneumogas- 
 tric nerves ; on the right of the aorta is the vena azygos ; between 
 this vein and the aorta is the thoracic duct ; superiorly is the 
 trachea ; inferiorly are the splanchnic nerves and some lymphatic 
 glands. To expose these last, we must remove the pleura, and a 
 layer of dense fascia which lines the chest outside it. 
 
 DESCENDING We have already traced the arch of the aorta to 
 
 THORACIC AORTA, the lower border of the body of the fourth dorsal 
 vertebra (p. 129). From this point, the aorta descends on the left 
 side of the spine, gradually approaching towards the middle line. 
 The artery, moreover, following the dorsal spinal curve is not 
 vertical, but concave forwards. Opposite 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, the oesophagus, and thoracic duct ; in front 
 of it are, the root of the left lung, and the pericardium. 
 Lower down the oasophagus is in front of the artery, and subse- 
 quently lies a little to its left side. Its branches will be described 
 presently. 
 
 VENA AZYGOS This vein commences in the abdomen by small 
 
 MAJOR AND branches from one of the lumbar veins of the right 
 
 MlNOB - side, 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 
 
142 
 
 THOEACIC DUCT. 
 
 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 covered by 
 pericardium. In its course it receives all the right intercostal 
 veins, the spinal veins, the oesophageal and commonly the right 
 FIG. 25. bronchial vein. Opposite the 
 
 sixth or seventh 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 from 
 one of the lumbar veins of 
 the left side, or from the left 
 renal. It then ascends on the 
 left side of the aorta, through 
 the aortic opening in the dia- 
 phragm. On a level wth the 
 sixth or seventh dorsal vertebra, 
 it passes beneath the aorta and 
 thoracic duct to join the azygos 
 major. Before^ passing beneath 
 the aorta it usually communicates 
 with the left superior intercostal 
 vein. It generally receives six 
 or seven of the lower intercostal 
 veins of the left side. These 
 azygos veins are provided with 
 imperfect valves, and are supple- 
 mental to the inferior vena cava. 
 
 THOKACIC DUCT The thoracic 
 
 AND EECEPTA- duct (figure 25) 
 CULUM CHYLI, j s a cana l about 
 
 eighteen inches long, through 
 which the contents of the lacteal 
 vessels from the intestines and the lymphatics from the lower limbs 
 
 DIAGRAM TO SHOW THE COURSE OF THE 
 VENA AZYGOS AND THE THORACIC DUCT. 
 
(ESOPHAGUS. 143 
 
 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 dilatation, the 
 duct ascends at first behind the aorta. Then getting to its right 
 side, it passes through the aortic opening of the diaphragm into 
 the chest, and runs up the posterior mediastinum, still along the 
 right side of the aorta, between this vessel and the vena azygos 
 major. Near the third dorsal vertebra, it passes behind the arch 
 of the aorta and the oesophagus, 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 con- 
 vexity upwards, and opens in front of the scalenus anticus into the 
 back part of the confluence of the left internal jugular and sub- 
 clavian 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 diameter of the duct varies in different 
 parts of its course ; at its commencement it is about three lines in 
 diameter, at the sixth dorsal it is about two lines, and it enlarges 
 again towards the termination. It receives the lymphatics from 
 the lower extremities, and from all the abdominal viscera (except 
 the convex surface of the liver and the abdominal walls), above 
 these it receives the lymphatics from the left side of the thorax, 
 the left lung, the heart, the left upper extremity, and the left side 
 of the head and neck. 
 
 The oesophagus is that part of the alimentary 
 
 (ESOPHAGUS. \ F J 
 
 canal which conveys the food from the pharynx 
 
 to the stomach. It commences at the lower border of the fifth 
 cervical vertebra, at the back of the cricoid cartilage ; runs down 
 
 * It is right to state that the thoracic duct varies in size in different individuals. 
 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 (Fleischmann ; 'Leichen- 
 offnungen,' 1815; also Morrison, 'Journal of Anat.,' vol. vi. p. 427). It has been seen 
 to terminate in the vena azygos (Miiller's 'Archiv,' 1834). 
 
144 (ESOPHAGUS. 
 
 first to the right side of the transverse portion of the arch of the 
 aorta, then through the posterior mediastinum in front of the 
 descending aorta, and passes through the oesophageal opening in 
 the diaphragm to the stomach. It is from nine to ten inches 
 long. Its course is not exactly straight ; in the neck, it lies 
 behind and a little 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 passes through the diaphragm. It has moreover an antero- 
 posterior curve corresponding to the curve of the spine. 
 
 The oesophagus, in the first part of its course, rests upon the 
 longus colli muscle, then upon the thoracic duct and the third, 
 fourth, and fifth intercostal vessels of the right side, and, lastly, it 
 lies in front, and slightly to the left side, of the aorta. In front 
 of it is the trachea and the left bronchus. Before it passes through 
 the diaphragm it lies in close contact with the pericardium (behind 
 the left auricle) for nearly two inches ; this accounts for the pain 
 which is sometimes experienced in cases of pericarditis, during 
 the passage of food. 
 
 In the neck, the oesophagus is in connection, laterally, with the 
 thyroid body, the common carotid and inferior thyroid arteries, and 
 the recurrent laryngeal nerves ; to the left of it is the thoracic duct. 
 In the thorax the aorta is to the left, and the vena azygos major 
 to the right, of the tube. As it passes down in the inter-pleural 
 space, it is in connection with both pleurae. The oesophagus is 
 surrounded by a plexus of nerves, formed by the pneumogastric 
 nerves, the left being in front, the right behind it. 
 
 The oesophagus is supplied with blood by the inferior thyroid, 
 the oesophageal branches of the aorta, the coronaria ventriculi, and 
 the left phrenic artery. It is supplied with nerves by the pneumo- 
 gastric and the sympathetic, which ramify between the two 
 muscular layers. The oesophagus is composed of three coats, an 
 external or muscular, a middle or areolar, and an internal or 
 mucous. The muscular coat consists of an outer longitudinal and 
 an inner circular layer of fibres. The longitudinal layer is parti- 
 cularly strong, and arranged in the upper part mainly in three 
 
PNEUMOGASTEIC IN THE CHEST. 145 
 
 bundles, an anterior and two lateral ; these, lower down, spread 
 out and form a continuous layer round the oesophagus and support 
 the circular fibres. Under the microscope the muscular fibres 
 composing the upper part are seen to consist entirely of the striped 
 variety ; at the lower part, almost exclusively of the non-striped 
 variety. The middle coat is composed of areolar tissue, and con- 
 nects 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 within the tube which lies flattened in front of the spine. 
 On the surface of the mucous membrane there are numerous 
 minute papillae placed obliquely. It is lined by a very thick layer 
 of scaly epithelium. In the submucous tissue are many small 
 compound racemose glands oesophageal glands especially to- 
 wards the lower end of the oesophagus. 
 
 COURSE AND ^ e right pneumogastric nerve enters the chest 
 
 BRANCHES OF THE between the subclavian artery and vein, descends 
 PNEUMOGASTRIC "by the side of the trachea, then passes behind the 
 n58 ' root of the right lung to the posterior surface of 
 
 the oesophagus, upon which it divides into branches, which form a 
 plexus (posterior oesophageal) upon that tube. The plexus then 
 reunites into a single trunk, which passes into the abdomen 
 through the oesophageal 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 ossophagus, 
 upon which it also forms a plexus (anterior oesophageal). The 
 branches of the pneumogastric nerve in the chest are as 
 follows : 
 
 a. The inferior laryngeal or recurrent. This nerve on the right 
 side turns under the subclavian and the common carotid arteries (p. 61) ; 
 on the left, under the arch of the aorta, below the ductus anteriosus, and 
 ascends to the larynx. It passes beneath the inferior thyroid artery, and 
 lying in the groove between the trachea and oesophagus, it enters the 
 larynx beneath the lower border of the inferior constrictor of the 
 
 L 
 
146 PXEUMOGASTRIC IN THE CHEST. 
 
 pharynx. It supplies with motor nerves all the muscles which act upon 
 the rima glottidis, except the crico-thyroid (supplied by the external 
 laryngeal nerve). As they turn beneath their respective arteries, they give 
 off branches to the deep cardiac plexus. 
 
 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. On both sides these branches pass to the deep 
 cardiac plexus. 
 
 c. Pulmonary branches. These accompany the bronchial tubes. 
 The greater number run behind the root of the lung, and constitute 
 the posterior pulmonary plexus. A few, forming the anterior pul- 
 monary plexus, supply the front part of the root of the lung. Both these 
 plexuses are joined by filaments from the sympathetic system. The 
 nerves of the lungs are, however, very small, and cannot be traced far 
 into their substance.* 
 
 d. (Esophageal plexus. Below the root of the lung each pneumo- 
 gastric 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 one, the continuation of the left pneumo- 
 gastric nerve lying in front of the oesophagus ; the other, that of the right, 
 lying behind it. Both nerves pass through the cesophageal opening in 
 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 should 
 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 under it ; also the first part of the left 
 subclavian, covered externally by the pleura. The pneumo- 
 gastric nerve must be traced behind the root of the left lung to 
 the oesophagus, and the cesophageal plexus of this side dissected. 
 Lastly, notice the lesser vena azygos which crosses under the aorta 
 aVout the sixth or seventh dorsal vertebra to join the vena azygos 
 major. 
 
 * Upon this subject, see the beautiful plates of Scarpa. 
 
SYMPATHETIC IN THE CHEST. 
 
 U7 
 
 THORACIC 
 PORTION OF THE 
 SYMPATHETIC. 
 
 Fig. 26. 
 
 This portion of the sympathetic system is gene- 
 rally composed of twelve ganglia covered by the 
 pleura ; one ganglion being found over the head of 
 
 each rib. Often there are only ten ganglia, in consequence of two 
 
 of them uniting here and there. The 
 
 first thoracic ganglion is the largest. 
 Each ganglion is connected by two 
 
 branches with the corresponding inter- 
 costal 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 four upper 
 
 ganglia are small and are distributed 
 
 as follows (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 
 pulmonai^y plexus. 
 
 The branches arising from the six 
 lower ganglia unite to form three nerves 
 the great splanchnic, the lesser, and 
 the smallest splanchnic nerves. 
 
 a. The great splanchnic nerve is 
 generally formed by branches from the 
 fifth or sixth to the tenth ganglion. 
 They descend obliquely along the sides 
 of the bodies of the dorsal vertebrae, 
 and unite into a single nerve, which 
 passes through the corresponding crus 
 of the diaphragm, and joins the semilunar ganglion of the abdo- 
 men, sending also branches to the renal and supra-renal plexuses. 
 
 b. The lesser splanchnic nerve is commonly formed by branches 
 from the eleventh and twelfth ganglia. It passes through the 
 
 x 2 
 
 DIAGRAM OF THE THORACIC PORTIOX 
 OF THE SYMPATHETIC. 
 
148 INTERCOSTAL VESSELS. 
 
 crus of the diaphragm to the coeliac plexus, and occasionally to 
 the renal plexus.* 
 
 c. The smallest splanchnic nerve (when present) comes from 
 the twelfth ganglion, passes through the crus of the diaphragm, and 
 terminates in the renal and coeliac plexuses. (This is not repre- 
 sented in the diagram.) 
 
 INTERCOSTAL The intercostal muscles occupy the intervals 
 
 MUSCLES. between the ribs. In each interval there are two 
 
 layers of muscles which cross like the letter X. The external 
 intercostals run obliquely from behind forwards, like the ex- 
 ternal oblique muscle of the abdomen. The internal run from 
 before backwards, like the internal oblique. Observe that a few 
 fibres of the inner layer pass over one or even two ribs, chiefly 
 near the angles, and more especially of the lower ribs, and 
 terminate upon a rib lower down.f 
 
 Neither of these layers of intercostal muscles extends all the 
 way between the sternum and the spine : the outer layer, begin- 
 ning 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 an intermixture of tendinous 
 and fleshy fibres ; and they are covered inside and outside the chest 
 by a glistening fascia, to give gi eater protection to the intercostal 
 spaces. 
 
 The external intercostal muscles elevate the ribs, and are 
 therefore muscles of inspiration. The internal intercostal muscles 
 depress the ribs, and are therefore muscles of expiration. 
 
 INTERCOSTAL There are twelve intercostal arteries on each side, 
 
 ARTERIES, which lie between the internal and external inter- 
 
 costal muscles, the last excepted. The two upper arteries are sup- 
 plied 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 upper intercostal arteries from the aorta ascend 
 
 * In a few instances we have traced a minute filament from one of the ganglia 
 into the body of a vertebra. According to Cruveilhier each vertebra receives one. 
 f These irregular muscular bundles are called the subcostal muscles. 
 
INTERCOSTAL VESSELS. 149 
 
 obliquely to reach their intercostal spaces ; the lower run more trans- 
 versely. As they pass outwards, they are covered by the pleura and 
 the sympathetic nerves ; the right, in addition, pass behind the oeso- 
 phagus, 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 runs along 
 the middle of the intercostal space, lying upon the external inter- 
 costal muscle, and 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 small branch, 
 the collateral intercostal, which runs for some distance along the 
 upper border of the rib below. After supplying the muscles, the 
 main trunk anastomoses with the anterior intercostal branch of the 
 internal mammary artery. In some cases this branch is 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 inter- 
 costal nerve. The continued trunk, gradually decreasing in size, 
 becomes 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 or dorsal branch passes backwards between the 
 transverse processes of the vertebrae, on the inner side of the 
 anterior costo-trans verse ligament, and is distributed to the muscles 
 and skin of the back. Each sends an artery through the inter- 
 vertebral foramen to the spinal cord and its membranes. 
 
 On the right side the intercostal veins terminate in the vena 
 
150 
 
 INTERCOSTAL NERVES. 
 
 FIG. 27. 
 
 azygos major ; on the left, the seven or eight lower terminate in the 
 vena azygos minor, the remainder in the left superior intercostal vein. 
 The usual relation which the intercostal vessels and nerve 
 bear to each other in the intercostal space, is, that the vein lies 
 uppermost, the nerve lowest, and the artery between them. 
 
 INTERCOSTAL These are twelve in number, and are the anterior 
 
 NERVES. 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 sensory. The sen- 
 sory root has a ganglion upon it. The two roots unite in the 
 intervertebral foramen and form a compound nerve. After passing 
 
 through the foramen, it is connec- 
 ted by two filaments with the sym- 
 pathetic nerve, and then divides into 
 an anterior and a posterior branch. 
 The posterior branches pass back- 
 wards between the transverse pro- 
 cesses of the dorsal vertebrae, and 
 supply the muscles of the back. 
 The anterior branches (the proper 
 intercostal nerves) proceed between 
 the intercostal muscles in company 
 with, and immediately below, their 
 corresponding arteries. In the an- 
 terior part of the intercostal space 
 the nerves lie in the substance of 
 the internal intercostal muscles, and 
 at the costal cartilages run through the muscles, passing in front 
 of the triangularis sterni and the internal mammary artery. Midway 
 between the spine and the sternum, they give off lateral cutaneous 
 branches, which supply the skin over the scapula and the thorax. 
 The intercostal nerves terminate in front in the anterior cutaneous 
 nerves ; the six upper, 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- 
 
 DIAGRAM OF A SPINAL NERVK. 
 
PULMONARY ARTERY. 151 
 
 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 lymphatic 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 their efferent vessels go 
 into the thoracic duct. We have seen these intercostal glands en- 
 larged and diseased in phthisis. 
 
 BBONCHIAL AND Small bronchial arteries, arising on the right 
 (ESOPHAGEAL side most frequently from the first aortic intercos- 
 
 ARTERIES. tal (3rd intercostal) artery, and on the left from 
 
 the thoracic aorta, accompany the bronchial tube on its posterior 
 aspect into the substance of the lung.* Their distribution and 
 office will be considered with, the anatomy of the lung. (Esopha- 
 geal arteries four or five in number proceed from the front of the 
 thoracic aorta to ramify on the oesophagus, where they inoscu- 
 late above with the cesophageal branches of the inferior thyroid, 
 and below with the coronaria ventriculi and phrenic arteries. 
 Small posterior mediastinal arteries axe given off from the 
 posterior part of the aorta r and supply the lymphatic glands and 
 tissues of the posterior mediastinum. 
 
 Having finished the posterior mediastinum, replace the lung, 
 and turn your attention once more to the great vessels at the root 
 of the heart. 
 
 PULMONARY This vessel is about two inches in length, and 
 
 ARTERY. conveys the venous blood from the heart to the 
 
 lungs. It proceeds from the upper part of the right ventricle, and 
 passes upwards and backwards along the left side of the aorta to 
 the concavity of the arch of the aorta, where it divides into 
 two branches, a right and a left,' one for each "lung. At its origin 
 it has on each side an auricular appendix and a coronary artery, 
 and lies in front of the root of the aorta. The pulmonary artery 
 and the aorta are surrounded for two inches by a common sheath of 
 
 * On the left side there are usually two bronchial arteries a superior, arising 
 from the highest part of the thoracic aorta, and an inferior, arising about an inch 
 lower down. 
 
152 NEEVES OF THE HEART. 
 
 pericardium. The right branch, the larger and longer, passed 
 below the arch of the aorta to the lung ; the left is easily followed 
 to its lung by removing the layer of pericardium investing it. 
 
 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 fcetal 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 and aorta are seen in 
 front of, and nearly at right angles to, the right pulmonary artery. 
 The vena azygos is seen arching over the right bronchus and ter- 
 minating in the vena cava superior. Notice, especially, a number 
 of lymphatic 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. 
 
 NERVES OF THE The nerves of the heart come from the pneumo- 
 HEABT AND OAK- gastric and its recurrent branch, and the three 
 MAC PLEXUSES. cervical ganglia of the sympathetic. The pneumo- 
 gastric gives off (generally) two or more filaments (cardiac) which 
 proceed from the main trunk in the neck, or from its recurrent 
 branch. The sympathetic sends three (cardiac) filaments ; one 
 from the upper cervical ganglion, a second from the middle, and 
 a th'ird from the lower ; and they are called, lespectively, the upper, 
 middle, and lower cardiac nerves of the sympathetic. 
 
 The minute and delicate nerves from these several sources on 
 each side, pass downwards to the base of the heart. They vary very 
 much in their precise relations to the great vessels upon which 
 they run ; but speaking generally, it may be said that the nerves 
 on the right side run chiefly behind the arch of the aorta, those 
 on the left, in front of it. Eventually they form, by their mutual 
 
NERVES OF THE HEART. 153 
 
 Subdivisions and interlacement, an intricate network of nerves, 
 termed, according to their position, the deep and the superficial 
 cardiac plexus. 
 
 The deep and larger cardiac plexus is situated behind the 
 arch of the aorta in front of the bifurcation of the trachea, and 
 immediately above the right pulmonary artery. To see it, the 
 pericardial covering of the aorta must be carefully removed, and 
 the vessel hooked forwards and to the left. 
 
 The superficial and smaller cardiac plexus lies in the con- 
 cavity of the arch of the aorta in front of the right pulmonary 
 artery. It is closely connected with the deep plexus ; and (gene- 
 rally) receives the upper cardiac branch of the left sympathetic, 
 and the lower cardiac branch from the left pneumogastric. 
 
 From the cardiac plexuses, as a common centre, the nerves pass 
 off to the heart, forming plexuses around the coronary arteries. 
 Thus, the anterior coronary plexus (derived chiefly from the 
 superficial cardiac) accompanies the anterior coronary artery. The 
 posterior coronary plexus (derived chiefly from the left side of 
 the deep cardiac) runs with the posterior coronary artery. The 
 two plexuses communicate at the apex of the heart, and in the 
 ventricular septum. 
 
 It is not an easy matter to trace the nerves into the substance 
 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 
 present 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; 
 
 OF THE ROOT OF divide the superior vena cava above the vena 
 EACH LUNG. azygos, and turn 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 pulmonary 
 plexuses, and some lymphatics. The following is the disposition of 
 the large vessels forming the root of the lung. In front are the 
 
154 
 
 CONSTITUENTS OP THE ROOT OF EACH LUNG. 
 
 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 
 
 FIG. 28. 
 
 DIAGRAM SHOWING THE CONSTITUENTS OF THE BOOT OF EACH LUNG, AND THEIR 
 RELATIYE POSITION '. ALSO THE POSITION OF THE TALTES OF THE HEART. THE 
 ARROWS INDICATE THE DIRECTIONS IN WHICH AORTIC AND MITRAL MURMURS ARE 
 PROPAGATED. 
 
 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 fig. 28. 
 
DISSECTION OF THE HEART. 155 
 
 DISSECTION OF THE HEART. 
 
 The heart is conical in form, and more or less convex on its 
 external aspect, with the exception of that portion lying on the 
 tendinous centre of the diaphragm, which is flattened. It is 
 situated obliquely in the thorax, and is completely surrounded by 
 the pericardium. It extends from the fourth to the eighth dorsal 
 vertebra, with its base directed upwards and to the right, its apex 
 downwards and to the left. The position which the heart bears 
 to the thoracic walls has been already described (pp. 134-137) ; it 
 varies however in different subjects, and as a rule is higher in the 
 dead body than during life, owing to the shrinking of the lungs. 
 
 Notice the two longitudinal grooves (sulci} on the front and 
 back surfaces of the heart, indicating the septum between the two 
 ventricles ; the anterior groove lies nearer to the left side, the 
 posterior, to the right side of the heart. 
 
 A circular groove, nearer the base, marks the separation between 
 the auricles and the ventricles. In the circular and longitudinal 
 furrows, surrounded by more or less fat, run the coronary vessels, 
 the nerves and the lymphatics. 
 
 SIZE AND The size of the heart is dependent upon so 
 
 WEIGHT. many conditions, that the following measurements 
 
 must be received with more or less limitation. An average heart will 
 measure in its transverse direction at the base, three and a half 
 inches ; in its length, about five inches ; in its thickness, two and a 
 half inches. The weight 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 generally. As a rule, the heart 
 gradually increases in length, breadth, and thickness from child- 
 hood to old age.* 
 
 The heart is a double hollow muscular organ ; that is, it is 
 composed of two hearts, a right and a left, separated by a septum, 
 and not communicating with each other except during uterine, 
 and rarely in adult, life. Each half consists of two cavities, an 
 auricle and a ventricle, which communicate by a wide orifice, 
 
 * Bizot, 'Mem. de la Soc. Med. d'Observ. de Paris,' torn. i. 1836. 
 
156 DISSECTION OP THE HEAET. 
 
 the auriculo-ventricular opening. The right half of the heart 
 propels venous blood to the lungs, and is called the pulmonary; 
 the left propels arterial blood from the lungs throughout 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 synchronous, 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 heart, and forms a quadrangular cavity, the 
 atrium or sinus venosus, between the two venae cavse, 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. 
 
 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. The interior is lined by a polished mem- 
 brane called the ' endocardium,' and 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 auricle to the edge 
 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 and a little to the left of the inferior, that 
 the streams of blood may not meet. 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 circular muscular fibres continuous with those of the auricle. 
 
DISSECTION OF THE HEART. 157 
 
 The posterior wall of the auricle is formed by the partition 
 between the auricles, the ' septum auricular um.' Upon this 
 septum, above and to the left of the orifice of the vena cava 
 inferior, is an oval depression (fossa ovalis), bounded by a pro- 
 minent border (annulus ovalis). This depression indicates the 
 remains of the opening (foramen ovale] 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 ' cyanosis.'' A valvular communica- 
 
 FIG. 29. 
 
 Auriculo-ventricular orifice . . 
 
 Fossa ovalis 
 
 Opening of the coronary vein . 
 Line of Eustachian valve. . . 
 
 DIAGRAM OF THE INTERIOR OF THE RIGHT AURICLE. 
 
 tion, however, not infrequently exists between the auricles in 
 this situation which is not attended with indications of this 
 disease. 
 
 A more or less noticeable fold of the lining membrane may be 
 seen projecting from the front margin of the v. c. inferior to 
 the front border of the fossa ovalis. It is the remnant of the 
 ' Eustachian* valvej which was of considerable size in foetal life, 
 and served to direct the current of blood from the v. c. inferior, 
 through the foramen ovale, into the left auricle. 
 
 * Eustachius, 'Libell. de vena sine pari.' 
 
158 DISSECTION OF THE HEART. 
 
 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 guarded 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 : ' 
 some being the orifices of small veins returning blood from the 
 substance of the heart ; others being simple depressions in the 
 muscular tissue. To the left, and rather in front of the orifice of 
 the vena cava inferior, is the auriculo-ventricular opening guarded 
 by the tricuspid valve. It is oval in form, and will admit the 
 passage of three fingers. Lastly, between the orifices of the supe- 
 rior and inferior venae cavae is a rounded elevation, the tubercle of 
 Lower (not seen in the diagram), which is supposed to direct the 
 current of blood in foetal life, from the superior cava to the auri- 
 culo-ventricular opening. 
 
 EIGHT YEN- This forms the right border and about two- 
 
 TRICLE. thirds of the front surface of the heart. To 
 
 examine its interior, 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, ' columnce carnecej of various 
 length and thickness, which cross each other in every direction ; 
 this muscular network is generally filled with coagulated blood. 
 Of these columnae carneae there are three kinds : one, stands out in 
 relief from the ventricle ; another is attached to the ventricle by 
 its extremities only, the intermediate portion being free ; a 
 third, and by far the most important set, called ' musculi papil- 
 laresj is fixed by one extremity to the wall of the ventricle, while 
 the other extremity gives attachment to the fine tendinous cords, 
 ' cordos tendinecej which regulate the action of the tricuspid valve. 
 The number of these musculi papillares is equal to the number of 
 the chief segments of the valve ; consequently there are three in 
 
DISSECTION OP THE HEA'IT. 159 
 
 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-wentricular, through which the blood passes from the 
 auricle, is oval in form and placed at the base of the ventricle. 
 It is surrounded by a ring of fibrous tissue, to which is attached 
 the tricuspid valve. From the upper and front part of the ven- 
 tricle, a smooth passage, ' infundibulum ' or ' conus arteriosusj 
 leads to the opening of the pulmonary artery. It is situated to the 
 left and in front of the auriculo- ventricular opening, and about 
 three-fourths of an inch higher. 
 
 TRICUSPID This is situated at the right auriculo-ventri- 
 
 VALVE. cular 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 a few muscular fibres may be demon- 
 strated. The bases of the valves are continuous with one another, 
 so that they form a membranous ring between the auricle and 
 ventricle, while the segments project into the cavity of the right 
 ventricle. Of its three principal flaps, the largest or anterior is 
 so placed, that, when not in action, it partially covers the orifice 
 of the pulmonary artery ; another, the internal, corresponds with the 
 inferior wall of the ventricle ; the third, or posterior, 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 
 proceeding from a given papillary muscle are attached to the 
 adjacent halves of two of the larger flaps, and to a smaller inter- 
 mediate 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 
 
160 DISSECTION OP THE HEART. 
 
 attached to the base of the valve ; those of the second, from four 
 to six, proceed to the middle of its ventricular surface ; those of 
 the third, which are the smallest and most numerous, are attached 
 to its free margin.* 
 
 PULMONARY OB These are three membranous folds, like watch- 
 SEMILUNAB pockets, situated at the orifice of the pulmonary 
 
 VALVES. artery. They are attached to the fibrous ring at 
 
 the root of the artery ; their free edges look upwards, and present 
 a festooned border, in the centre of which is a small cartilagi- 
 nous body called the nodulus or corpus Arantii.] The use 
 of these bodies is plain. 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 no- 
 dules, so that the closure becomes complete. 
 
 The valves are composed of folds of the endocardium, or 
 lining membrane of the heart. Between the folds is a thin layer 
 of fibrous tissue, which is prolonged from the fibrous 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 
 which is thinner than the rest, and consists of the endocardial mem- 
 brane. This crescent-shaped portion, called the lunula, is not wholly 
 
 * 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-vontricular 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 distension and figure requisite to block up the aperture 
 into the auricle. It is obvious that the tendinous cords will prevent the valve from 
 flapping 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. 
 
 f So called after Arantius, an Italian anatomist, who lived towards the close of 
 the sixteenth century. 
 
DISSECTION OP THE HEART. 161 
 
 without fibrous tissue ; a thin tendinous cord runs along its free 
 edge, to give it additional strength to resist the pressure of the 
 blood. Behind each of the valves the artery bulges and forms 
 three slight dilatations called the sinuses of Valsalva.* These, 
 we shall presently see, are more marked at the orifice of the aorta. 
 The action of these valves is plain. 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 regurgitating 
 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). The valves are 
 capable of sustaining a weight of sixty-three pounds before they 
 give way.f 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 pulmonary veins, two on either side, which return the 
 oxygenated blood from the lungs. From its upper and left side, the 
 auricular appendage 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, the 
 atrium, is smooth and flat, excepting in the appendix, which 
 contains the musculi pectinati. Notice the openings of the four 
 * An Italian anatomist, b. 1666, d. 1723. t Haller. 
 
 M 
 
162 DISSECTION OF THE HEAET. 
 
 pulmonary veins. Upon the septum between the auricles is a 
 semilunar depression indicating the remains of the foramen ovale. 
 At the lower and front part of the auricle is the auriculo-ventri- 
 cular opening. It is oval, with its long axis nearly transverse, 
 and in the adult will admit the passage of two fingers. 
 
 LEFT VEN- This occupies the left border, and forms the 
 
 TEICLE. apex of the heart. One third of it only is seen 
 
 on the anterior surface, the rest being on the posterior. To 
 examine the interior, raise a triangular flap, with the apex below, 
 from its front wall. Observe that its wall 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 chordae, tendinece 
 stronger than those of the right ventricle, but their arrangement 
 is precisely similar. From the upper and back part of the ven- 
 tricle, a smooth passage leads to the orifice of the aorta. This 
 orifice is placed in the groove between the two auricles, and some- 
 what in front and to the right side of the left auriculo-ventricular 
 opening. 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. 
 
 The circumferences of the four orifices are 
 
 oIZE OF THE 
 
 AUBICULO-VENTEI- as follows i that of the tricuspid orifice, 4*74 inches ; 
 CULAB AND ABIE- that of the mitral 4 inches ; that of the pulmonary, 
 EIAL OPENINGS. ^^ incheg . and thftt of the aortic? 3^4 i nc h es .* 
 
 * Dr. Peacock, ' Croonian Lectures,' 1865. 
 
DISSECTION OP THE HEART. 163 
 
 COBONABY The heart is supplied with blood by the two 
 
 AETEEIES. coronary arteries, a right or posterior, and a left or 
 
 anterior. They are about the size of a crow's quill. Both arise 
 from the aorta just above the free margins of the two anterior 
 semilunar valves, and thus always allow the passage of blood ; 
 both run in the furrows on the surface of the heart ; both are 
 accompanied by the cardiac nerves and by lymphatics. 
 
 The anterior or left coronary artery, the smaller of the two, 
 arises from the left side of the aorta. It appears between the 
 pulmonary artery and the appendix of the left auricle, and then 
 divides into two branches : one which seems the continuation of 
 the main trunk and runs down the inter-ventricular furrow on 
 the anterior surface of the heart to the apex; the other passes 
 transversely to the left, in the left auriculo-ventricular groove to 
 the back of the heart. 
 
 The posterior or right coronary artery arises from the right 
 side of the aorta, and descends obliquely between the pulmonary 
 artery and the appendix of the right auricle. It then turns to the 
 right in the groove between the right ventricle and auricle to the 
 back of the heart, where it divides into two branches; one of 
 which descends in the posterior inter-ventricular furrow towards 
 the apex of the heart ; the other, which appears to be the 
 continuation of the main trunk, runs in the left auriculo-ven- 
 tricular groove. Besides these branches, the right coronary gives 
 off a large branch which runs along the free border of the right 
 ventricle. 
 
 Thus, the leading trunks of the coronary arteries run in the 
 furrows of the heart, usually surrounded by fat. Their numerous 
 branches supply the walls of the auricles and ventricles, and their 
 terminations communicate slightly with each other. 
 
 COEONABT The vein which corresponds with the anterior 
 
 VEINS AND SINUS, coronary artery ascends in the inter-ventricular 
 sulcus, and then curves round the left side of the heart in the 
 auriculo-ventricular groove, where it takes the name of the great 
 cardiac vein. This vein soon dilates into a large trunk, the 
 coronary sinus, which opens into the back of the right auricle. 
 
 M 2 
 
164 
 
 DISSECTION OF THE HEART. 
 
 Other veins, known as the posterior cardiac, three or four in 
 number, ascend along the posterior surface of the heart, to open 
 by valved orifices into the coronary sinus ; while others, the anterior 
 cardiac veins, are seen running up on the anterior surface of 
 the right ventricle to terminate directly in the right auricle. 
 The coronary sinus is about an inch in length, and its orifice 
 in the right auricle is guarded by a valve (valve of Thebesius} to 
 prevent regurgitation of the blood. It is covered and more or 
 less supported in its course by muscular fibres passing from one 
 auricle to the other. 
 
 FIG. 30. 
 
 DIAGRAM OF THE RELATIVE POSITION OF THK VALVES OF THE HEART, 
 SEEN FROM ABOVE. 
 
 A is placed on the triangular interval where the fibrous skeleton is the thickest. 
 
 FIBROUS ZONES 
 OR SKELETON OF 
 THE HEART. 
 
 What may be termed the fibrous skeleton of 
 the heart, consists of four rings which surround, 
 respectively, the four orifices at its base : namely, 
 the two auriculo-ventricular, the aortic, and the pulmonary. These 
 rings give attachment by their external circumference to the 
 muscular fibres of the heart, and from their internal circumference 
 send fibrous prolongations to form the framework of the several 
 valves. The skeleton is strongest just in the triangular interspace 
 
DISSECTION" OP THE HEAET. 165 
 
 between the aortic and the two auriculo-ventricular orifices (letter A 
 in fig. 30). In some animals, as in the ox and the elephant, there 
 is here an irregularly triangular bone, known as the ' os cordis.' 
 
 The relative position of these rings is best seen by removing 
 the auricles and the great vessels at the base of the heart leaving 
 the several valves, and looking at them from above, as shown in 
 the diagram. The pulmonary ring is on the highest level, and 
 nearest to the sternum ; below it, is the aortic ring lying between 
 and in front of the auriculo-ventricular rings, which are on the 
 lowest level. 
 
 ATTACHMENT OF ^^ e n ^rous rings at the arterial orifices present 
 THE LAKGE AETE- three festoons with their concavities directed up- 
 RIES TO THE wards. These give attachment, above, to the middle 
 
 coat of the artery ; below, to the muscular fibres 
 of the heart ; and, internally, to the fibrous tissue of the valves. 
 The vessels are also connected to the heart by the serous layer of 
 the pericardium, and by a continuation of the lining membrane of 
 the ventricle. 
 
 This smooth membrane lining the cavities of 
 
 ENDOCABDIUM. ... 
 
 the heart resembles the visceral layer of the peri- 
 cardium, and is continuous with the lining membrane of the 
 blood-vessels. It may be easily stripped off, and is thin and 
 semi-transparent, thicker in the left than in the right cavities, 
 thickest of all in the left auricle. It consists of three layers : 
 1, a layer of flattened polygonal cells, resting upon, 2, some elastic 
 fibres resembling the fenestrated coat of an artery, and, 3, a thin 
 layer of connective tissue. 
 
 ARRANGEMENT The muscular fibres of the heart are of the 
 
 OF THE MUSCULAR striped variety, but differ from ordinary striped 
 FIBRES OF THE muscular tissue, in being smaller, destitute of sarco- 
 lemma, branched, nucleated, and involuntary. 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 transversely 
 across the auricles, and are most marked on the anterior surface ; 
 some pass into the septum. Of the deeper fibres, some are annu- 
 
166 DISSECTION OP THE HEART. 
 
 lar and surround the auricular appendages and the entrance of 
 the great veins, upon which a few may be traced for a short dis- 
 tance ; others, looped, run over the auricles, and are attached in 
 front and behind to the auriculo-ventricular rings. 
 
 ARRANGEMENT Speaking generally, it may be said that the 
 OF THE MUSCULAR right and left ventricles of the heart are two 
 FIBRES OF THE conical muscular sacs, enclosed in a third, which 
 
 UTRICLES. no on j v enve i p es them, but is reflected into the 
 
 interior of both, at their apices, so as to line their cavities. All 
 the muscular fibres are attached by one end to the fibrous rings of 
 the orifices, and, by the other end, after a more or less spiral 
 course, they reach the rings again, either directly or through the 
 medium of the chordae tendinese and valves. 
 
 Let us first take the arrangement of the superficial fibres, 
 those, namely, of the sac which envelopes both ventricles. The 
 fibres covering the anterior surface of the heart start from the 
 right auriculo-ventricular and pulmonary rings, and run more or 
 less spirally from right to left towards the apex of the heart : those 
 covering the posterior part of the heart start from the auriculo- 
 ventricular rings, and run more or less spirally from left to right 
 to reach the apex. At the apex what becomes of the fibres ? They 
 form a whorl, are reflected upon themselves, and enter the interior 
 of the ventricles so as to form their innermost muscular lining in 
 other words, the fleshy columns of their cavities. 
 
 VEHTRICULAR Each sac consists of muscular fibres, arranged 
 
 SACS. more or less transversely, which arise from some 
 
 part of the ring, run round the ventricle, and are fixed to another 
 part of the ring. Thus each sac forms a hollow conical barrel, 
 open at both ends ; the broad end representing the orifice of the 
 ring, the narrow end representing the orifice through which the 
 fibres of the common sac enter the ventricles.* 
 
 THICKNESS OF The average thickness of the right auricle is 
 
 THE CAVITIES. about one line ; that of the left, one and a half. 
 
 * For further information on this subject, consult Pettigrew, 'Philosoph. Trans- 
 actions,' 1861; Dr. Sibson, 'Medical Anatomy,' 1869; Winckler, ' Miiller's Archiv,' 
 1865; Quain's ' Anatomy,' vol. ii. p. 257, 1876. 
 
PECULIARITIES OF FCETAL HEART. 
 
 167 
 
 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. 
 
 FIG. 31. 
 
 SUP" v. c 
 
 FORAMEN OVALE 
 
 PLAC ENTA 
 
 SCHEME OF THE FCETAL CIRCULATION. 
 
 PECULIARITIES The heart of the foetus differs from that of the 
 
 i)F FCETAL HEART. a dult in the following points : 1 . The Eustachian 
 valve is well developed in order to guide the current of blood from 
 
168 F(ETAL CIRCULATION. 
 
 the vena cava inferior into the foramen ovale. 2. The foramen 
 ovale is widely open. 3. The right and left pulmonary arteries 
 are very small and ill developed, so as to admit very little blood 
 to the lungs. 4. The ductus arteriosus (from the pulmonary 
 artery to the aorta) is widely open. 5. The right and left ventricles 
 are of equal thickness because they have equal work to perform. 
 
 F(ETAL CIRCULATION. 
 
 CIRCULATION OF The umbilical vein (fig. 31), bringing pure blood 
 THE BLOOD IN THE from the placenta, enters at the umbilicus, and 
 passes to the 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 portae, 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 foramen ovale into the left auricle. From the 
 left auricle it runs into the left ventricle, and thence through the 
 aorta (only a small quantity passing into the descending thoracic 
 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 ductus arteriosus, into the end 
 of the arch of the aorta ; only a very small quantity of it goinp; 
 to the lungs. From the aorta, part of the blood is distribute- ' 
 to the pelvis and lower extremities ; part is conveyed through the 
 umbilical arteries to the placenta, where it becomes oxygenated. 
 
 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. 
 
STRUCTURE OF THE LUNGS. 169 
 
 2. The ductus venosus also becomes closed about the same 
 period. 
 
 3. The foramen ovate and ductus arteriosus become com- 
 pletely closed from the sixth to the tenth day. 
 
 4. The pulmonary arteries enlarge and convey venous blood 
 to the lungs. These organs during foetal life receive only a small 
 quantity of blood from these arteries. 
 
 5. The hypogastric arteries become obliterated on the fourth 
 or fifth day after birth. 
 
 STEUCTUKE OF THE LUNGS. 
 
 The lungs are very vascular spongy organs in which the blood 
 is .oxygenated by exposure to atmospheric air. Their situation and 
 shape have been briefly described (p. 140). We must now examine 
 the trachea, the common air-passage to both lungs, and then 
 trace this tube downwards to its bifurcation into the two bronchi, 
 which, with their minute subdivisions, form the main structure 
 of the lungs. 
 
 This is a partly membranous, partly cartila- 
 ginous tube, and is situated in the middle line. 
 It extends from the cricoid cartilage, i.e. opposite the upper 
 border of the sixth cervical vertebra, to the third dorsal ver- 
 tebra, where it divides into two tubes, the right and left 
 bronchus : one for each lung. Its length is from four to four 
 and a half inches, and its width from eight to ten lines ; but these 
 measurements vary according to the age of the patient and the 
 capacity of the lungs. The trachea is surrounded by a quantity 
 of loose connective tissue, so as to allow of its free mobility. It 
 is kept permanently open by a series of incomplete 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 a fibro- 
 muscular membrane. This deficiency allows the trachea to enlarge 
 or diminish its calibre ; and for this purpose the membranous part 
 
170 STEUCTUEE OF THE LUNGS. 
 
 of the tube is provided with unstriped muscular fibres which can 
 approximate the ends of the rings. 
 
 The relations of the trachea to the surrounding parts should 
 be considered, first, in the neck, and then within the thorax. 
 
 In the neck, it has in front of it the isthmus of the thyroid 
 body, the sterno-hyoid and sterno-thyroid muscles, the middle 
 thyroid veins, two layers of the deep cervical fascia, the arteria thy- 
 roidea ima, if present, and (at the root of the neck) the innomi- 
 nate and left common carotid arteries. Laterally, it is in relation 
 with the lobes of the thyroid body, the common carotid arteries, the 
 recurrent laryngeal nerves, and the inferior thyroid arteries. 
 Behind it, is the oesophagus, inclining slightly to the left. 
 
 In the chest, in front of the trachea are the origins of the 
 sterno-hyoid and thyroid muscles, the left brachio-cephalic vein, 
 the first parts of the innominate and left common carotid arteries, 
 the transverse portion of the arch of the aorta, and the deep cardiac 
 plexus. On the right side are the pleura and right pneumogastric 
 nerve ; on the left, the pleura, the left carotid, the left pneumo- 
 gastric, cardiac, and recurrent laryngeal nerves. 
 
 BRONCHI, RIGHT The two bronchi differ in length, direction, and 
 AND LEFT. diameter. The right is shorter than the left, 
 
 about an inch long, and passes more horizontally to the root of its 
 lung, on a level with the fourth dorsal vertebra. It is larger in all 
 its diameters than the left ; hence, foreign bodies which have acci- 
 dentally dropped into the trachea are more likely to be carried 
 into the right bronchus by the current of the air. The left is 
 about two inches in length, and, descending more obliquely to its 
 lung than the right, enters it on a level with the fifth dorsal 
 vertebra. 
 
 The vena azygos major arches over the right bronchus, to 
 terminate in the superior v.c. The left bronchus passes under 
 the arch of the aorta in front of the CESophagus, and subsequently 
 crosses in front of the descending aorta. 
 
 The cartilages of the trachea vary in number from sixteen to 
 twenty, of the right bronchus from six to eight, and of the left 
 from nine to twelve. Those of the trachea form about two-thirds 
 
STRUCTUEE OP THE LUNGS. 171 
 
 of a circle, somewhat like a horseshoe in shape, and about one-sixth 
 of an inch in their vertical direction. The first cartilage is the 
 broadest, and that 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 connective and 
 elastic tissues. This membrane is attached above to the circum- 
 ference of the cricoid cartilage, and is continued through the 
 whole extent of the trachea and bronchial tubes. Posteriorly, 
 where the cartilages are deficient it maintains the integrity of the 
 tube. In this tissue, which is of a pale reddish colour, is a layer 
 of unstriped muscular fibres, arranged in a transverse and a longi- 
 tudinal direction. 
 
 MUSCUIAB This thin stratum of unstriped muscular fibres 
 
 TISSUE, is exposed when the fibrous membrane and tracheal 
 
 glands have been removed. Some of the fibres extend transversely 
 between the posterior free ends of the cartilages, while some are 
 arranged in longitudinal bundles. By their contraction they 
 approximate the ends of the cartilages, and diminish the calibre 
 of the trachea. 
 
 This is chiefly found in the membranous part of 
 
 ELASTIC TISSUE. .../., . .,.,,. 
 
 the tube, and its fibres run in a longitudinal direc- 
 tion. It is this tissue which raises the mucous membrane into 
 folds, and its elasticity admits of the elongation and the recoil of 
 the tube. 
 
 TKACHEAL Between the fibrous and muscular layers of the 
 
 GLANDS. trachea are a number of small mucous glands, 
 
 most numerous on the posterior part of .the tube. They are 
 compound racemose glands, lined with columnar epithelium, and 
 in health their secretion is clear, and just sufficient to lubricate 
 the air-passages. In bronchitis they are the sources of the abun- 
 dant viscid expectoration. 
 
 Mucous MEM- The mucous membrane lining the air-passages 
 
 BEANE - is a continuation of that of the larynx. Its colour 
 
 in the natural state is nearly white, but in catarrhal affections it 
 
172 STEUCTUEE OP THE LUNGS. 
 
 becomes bright red, in consequence of the accumulation of blood 
 in the capillary vessels. It is continued into the ultimate air- 
 cells, where it becomes thinner and more transparent. In its 
 deeper layer is found a considerable amount of elastic tissue ; in 
 its superficial layer a quantity of lymphoid tissue. Its surface is 
 lined with a layer of columnar ciliated epithelial cells. The 
 vibratile movement of the cilia is directed in such a way as to 
 favour the expectoration of the mucus. The ciliated epithe- 
 lium 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 of the lung. 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 ; hence, when a bronchial tube is obstructed, all supply of 
 air is cut off from those cells to which it leads. 
 
 The several tissues, cartilaginous, fibrous, muscular, mucous, 
 and glandular, which 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 car- 
 tilaginous rings necessary to keep the larger tubes permanently 
 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 when the tube is reduced to one- 
 fortieth of an inch in diameter. The smallest air-passages are 
 entirely membranous, being formed of fibrous, elastic, and muscular 
 tissues. 
 
 The lungs are composed of cartilaginous and 
 THE LUNGS. & / . 6 . 
 
 membranous tubes, of which the successive sub- 
 divisions 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 concerned in their nutrition ; of 
 lymphatics and nerves. These component parts are united by 
 
STRUCTURE OF THE LUNGS. 173 
 
 connective tissue, and covered externally by pleura. The part 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 com- 
 pressed by effusion into the chest, or rendered solid by inflam- 
 mation. 
 
 CONTKACTIBI- When an opening is made into the chest, the 
 
 LITY OF THE lung, which was in contact with the ribs, imme- 
 
 NG> diately recedes from them, and, provided there be 
 
 no adhesions, gradually contracts. If the lungs be artificially 
 inflated, either in or out of the chest, we observe that they 
 spontaneously expel a part of the air. This disposition to 
 contract, in the living and the dead lung, is due 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 -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 amount 
 of blood, and is always 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 
 
 * In some animals, the seal especially, the elasticity of this tissue is very strongly 
 marked. 
 
174 STRUCTURE OP THE LUNGS. 
 
 * 
 
 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. 
 
 In the male the average weight of the right 
 lung is 24 oz., that of the left, 21 oz. ; in the female 
 the average is about 17 oz. on the right, and 15 oz. on the left side. 
 The total capacity of the lungs in an adult male of ordinary 
 height is 282 cubic inches ; and the amount of air still contained 
 in the lungs after a forced expiration has been estimated at 57 cubic 
 inches. The difference between these volumes indicates the amount 
 of air which can be inhaled, from the deepest expiration to the fullest 
 inspiration, and has been termed the vital capacity of the lungs.* 
 LOBULES OF THE The surface of the healthy lung is marked by 
 LuNG - faint 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 
 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 is called ' inter lobular emphy- 
 sema.' When infiltrated with serum it constitutes e oedema ' of 
 the lung. 
 
 Each lobule receives a small bronchial tube, lobular bronchial 
 tube, which subdivides into smaller branches. Thus reduced in 
 size, the walls of the tubes 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.f Each 
 tube finally leads into an irregular passage, lobular passage, from 
 which proceed on all sides numerous dilatations : these are the 
 
 * Hutchinson, ' Med. Ghir. Trans.,' vol. xxix. 1846. 
 
 t In phthisis the expectoration contains some of the debris of this elastic frame- 
 work of the air-vesicles; it can be seen under the microscope, and is a test of the 
 character of the sputa. 
 
STEUCTUEE OP THE LUNGS. 
 
 175 
 
 FIG. 32. 
 
 air-cells or alveoli, which vary from ^ to -^ of an inch in 
 diameter (fig. 32). The air-cells themselves present a number 
 of shallow depressions, separated by somewhat prominent parti- 
 tions, so that their interior has a honey- 
 combed appearance, as shown in fig. 32. 
 The purpose of these 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 structure of the air-cells differs 
 in some important features from that 
 of the small bronchial tubes ; the 
 muscular tissue disappears, the elastic 
 tissue is no longer arranged in bundles, 
 but becomes frayed out and inter- 
 mingled with the connective tissue, 
 and the ciliated epithelium is replaced U ATE AIB-CELLS OF THE 
 
 , .1, ,. . , , (FROM KOLLIXER). MAGNIFIED 
 
 by a single layer of squamous epithe- TWENTY . FITE TIMES . 
 
 Hum. 
 
 PULMONARY The branches of the pulmonary artery subdivide 
 
 VESSELS. with the bronchial tubes. Their ultimate ramifica- 
 
 tions spread out in such profusion beneath the epithelium of the 
 air-cells, that a well-injected lung appears a mass of the finest 
 network of capillaries. This network is single and is so close that 
 the interstices are even narrower than the vessels, which are on an 
 average about 30 1 00 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 vessels, 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 
 
17(3 STRUCTURE OF THE LUNGS. 
 
 vessels are exposed to the action of the air. The blood, circulating 
 in steady streams through this capillary plexus, returns through 
 the pulmonary veins. These, at first extremely minute, gradually 
 coalesce into larger and larger branches which anastomose very 
 freely, and accompany the arteries. They finally emerge from the 
 root of the lung by two large trunks which carry the oxygenated 
 blood to the left auricle of the heart. The pulmonary veins are 
 not provided with valves. 
 
 BRONCHIAL These are small arteries, two or more in number 
 
 AHTEBIES. for each lung. The right arises either from the 
 
 first aortic intercostal, or, conjointly with the left bronchial, from 
 the thoracic aorta. The left comes from the thoracic aorta. They 
 enter the lung behind the divisions of the bronchi, which they 
 accompany. They are the proper nutritive vessels of the organ. 
 The bronchial vessels are distributed in various ways : some of 
 their branches supply the coats of the air-passages, the large blood- 
 vessels and the lymphatic glands ; others the interlobular tissue : 
 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 intercostal vein. 
 
 The nerves of the lung are derived from the pneumogastric and 
 the sympathetic. They enter with the bronchial tubes, forming a 
 plexus in front and behind them, anterior and posterior pulmo- 
 nary plexus, in which are found minute ganglia. 
 
 The lymphatics of the lungs commence in the lymphatic 
 capillaries in the interlobular tissue, and thence pass to the surface 
 forming a network which communicates with the subpleural 
 lymphatic plexus : others take their origin in the mucous mem- 
 brane of the bronchial tubes, and all eventually enter the 
 bronchial glands. Of these, the larger are situated about the 
 bronchi near the root of the lung, particularly under the bifurcation 
 of the trachea. 
 
DISSECTION OF THE PHARYNX. 177 
 
 DISSECTION OF THE PHAEYNX. 
 
 To obtain a view of the pharynx, cut through 
 the trachea, the oesophagus and the large vessels of 
 the neck, and then separate them from the bodies of the cervical 
 vertebrae, with which they are loosely connected. The base of the 
 skull should be sawn through transversely between the vertebral 
 column and the styloid processes of the temporal bone, so as to 
 leave the pharynx and the larynx attached to the anterior half of 
 the section. Horsehair should then be introduced through the 
 mouth and oesophagus to distend the walls of the pharynx. 
 
 PHAETNX: GENE- The term pharynx is applied to that part of the 
 HAL DESCRIPTION. alimentary 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 broadest portion is situated opposite the os hyoides. 
 Its upper part is attached to the basilar process of the occipital 
 bone and the petrous portions of the temporal bones ; thence it 
 extends to the lower border of the cricoid cartilage, where the 
 continuation of it takes the name of oesophagus. The bag is 
 connected, in front, to the sides of the posterior nares, the 
 tongue, the hyoid bone and the larynx; and, behind, to the 
 bodies of the cervical vertebrae by loose connective tissue which 
 never contains fat. In abscesses at the back of the pharynx, 
 the pus is seated in this tissue. Parallel ivith, and close to its 
 sides, run the internal carotid arteries, the internal jugular 
 veins, the eighth, ninth and sympathetic nerves. Its dimensions 
 are not equal throughout. Its breadth at the upper part is equal 
 to that of the posterior openings of the nose ; here it is only 
 required to convey air : but it becomes much wider in the situa- 
 tion 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. 
 
178 DISSECTION OP THE PHARYNX. 
 
 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 thin fascia, termed the pharyngeal fascia. 
 It is the layer of deep cervical fascia behind the pharynx, and 
 must not be confounded with the proper pharyngeal aponeurosis, 
 which intervenes between its muscular and mucous walls. 
 
 At the back of the pharynx, near the base of the skull, are a 
 few lymphatic glands. They sometimes enlarge, and form a per- 
 ceptible tumour in the pharynx. 
 
 In removing the fascia from the pharyngeal muscles notice 
 that a number of veins ramify and communicate in all directions. 
 They constitute the pharyngeal venous plexus, and terminate in 
 the internal jugular veins. 
 
 CONSTRICTOR They are three in number, and arranged so that 
 
 MUSCLES OF THE they overlap each other i.e. the inferior overlaps 
 PHARYNX. tne m iddle, and the middle the superior (fig. 33). 
 
 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 longitu- 
 dinal line called the raphe. 
 
 The inferior constrictor arises from the side of the cricoid 
 cartilage, from the oblique ridge and the upper and lower borders 
 of the thyroid cartilage. Its fibres expand over the lower part 
 of the pharynx. The superior fibres ascend ; the middle run 
 
 * 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. 
 
DISSECTION OF THE PHARYNX. 
 
 179 
 
 transversely ; the inferior descend, and are identified with the 
 oesophagus. Beneath its lower border the recurrent laryngeal 
 nerve enters the larynx. Its nervous supply is from the pharyn- 
 geal plexus. 
 
 FIG. 33. 
 
 j\J Tensor palati. 
 
 Levator palati. 
 
 Orbiciilaris oris . _ 
 
 Pterygo-maxill ary 
 
 ligament . . 
 
 Mylo-hyoideus . 
 
 Os hyoides . . . 
 Thyro-hyoid liga- 
 ment . . . . 
 
 Pom urn Adami 
 
 Cricoid cartilage 
 
 Trachea . . . 
 
 Glosso-pharyngeal n. 
 Stylo-pharyngeus. 
 
 Superior laryngeal 
 nerve and artery. 
 
 External laryngeal u. 
 Crico-thyroid. 
 
 Inferior laryngeal n. 
 (Esophagus. 
 
 MUSCLES OF THE PHARYNX. 
 
 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 
 
 N 2 
 
180 DISSECTION OF THE PHARYNX. 
 
 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. Its nerve comes from the pharyngeal plexus. 
 
 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 back part of 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. Its nerve comes from the pharyngeal plexus. 
 
 The upper border of the superior constrictor presents, on either 
 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. 33). 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. 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 con- 
 strictors so as to be able to lift up the pharynx in deglutition ; but 
 most of them are inserted into the superior and posterior margins 
 of the thyroid cartilage. 
 
 PHARYNGEAL The pharyngeal aponeurosis intervenes between 
 
 MEMBRANE OR the muscles and the mucous membrane of the 
 APONEUROSIS. pharynx. It is attached to the basilar 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 
 
DISSECTION OF THE PHARYNX. 
 
 181 
 
 deficient ; but it gradually diminishes in thickness as it descends, 
 and is finally lost on the oesophagus. Notice the number of 
 
 Fto. 34. 
 
 Eustachian tube. 
 Levator palati m. 
 
 Tensor palati in. 
 Hamular process. 
 
 Posterior palatine arch. 
 Tonsil. 
 
 Anterior palatine arch. 
 
 Epiglottis. 
 Aryteno-epiglottidean fold. 
 
 Opening into the larynx. 
 
 Opening into theresopliagus. 
 
 DIAGRAMMATIC VIEW OF THE PHARTNX LAID OPEN FHOM BEHIND. 
 
 mucous glands upon this aponeurosis, especially near the base of 
 the skull and the Eustachian tube. These glands sometimes 
 enlarge and occasion deafness from the pressure on the tube. 
 
182 DISSECTION OF THE PHARYNX. 
 
 OPENINGS INTO Lay open the pharynx by a longitudinal incision, 
 THE PHARYNX. a nd observe the seven openings leading into it 
 (fig. 34): 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.* 
 
 Mucous These structures are lined by mucous membrane 
 
 MEMBRANE. common to the entire tract of the respiratory 
 
 passages and the alimentary canal. But this membrane presents 
 varieties in the different 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 delicate in its texture, and lined by columnar 
 ciliated epithelium like the rest of the air-passages. But opposite 
 the fauces, the mucous membrane 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 secretion from the numerous 
 mucous glands which are situated in the submucous tissue through- 
 out the whole extent of the pharynx, particularly in the neighbour- 
 hood of the Eustachian tubes. 
 
 POSTHRIOE These are two oval openings, each of which is 
 
 OPENINGS OF THE about an inch in the long, and half an inch in the 
 NASAL Fossa. sllor t diameter. They ate bounded above by the 
 
 * On reflecting the mucous membrane at the pharyngeal termination of the 
 Eustaclrian tube, a thin pale muscle, the salpingo-pharyngeus, can be made out. It 
 arises by a thin tendon from the Eustachian tube, and joins the palato-pharyngeus. 
 It is lost among the fibres of the constrictor muscles. 
 
SOFT PALATE. 183 
 
 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. 
 
 On removing 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. 
 
 ISTHMUS This name is given to the opening by which the 
 
 FAUCIUM. 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 border of the hard 
 palate, and laterally to the side of the pharynx. Posteriorly it has 
 a free edge, and a pendulous projection in the centre, 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 or raphe, indicating its original formation by 
 two lateral halves. The soft palate, when at rest, hangs obliquely 
 downwards and backwards ; but in swallowing, it is raised to the 
 horizontal position by the levatores palati, comes into apposition 
 with the back of the pharynx, and thus prevents the food from 
 passing through the nose. 
 
 On making a perpendicular section through the soft palate, 
 you see that the great bulk of it is made up of muciparous glands, 
 which lie thick on its under surface to lubricate the passage of 
 the food. Above these glands is the palato-glossus, then the 
 aponeurosis of the palate ; still higher, are the two portions of the 
 palato-pharyngeus (separated by the fibres of the levator palati), 
 the azygos uvulae, and, lastly, the nasal mucous membrane. The 
 soft palate is supplied with blood by the descending palatine 
 branch of the internal maxillary, and the ascending palatine branch 
 of the facial. Its nerves are derived from the palatine branches of 
 
184 60FT PALATE. 
 
 the second (superior maxillary) 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 muciparous glands, and 
 a small muscle, the azygos uvulce. Its length varies 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. 
 
 ARCHES OF THE The soft palate is connected with the tongue 
 PALATE. an( j pharynx 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 deglutition. The anterior, enclosing the palato-glossi 
 muscles, contract so as to prevent the food from coming back 
 into the mouth : the posterior, enclosing the palato-pharyngei, 
 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. 
 
 MUSCLES OF THE The muscles of the soft palate lie immediately 
 SOFT PALATE. beneath the mucous membrane. There are 
 
 five pairs namely, the levatores palatj, 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. 
 
SOFT PALATE. 185 
 
 IRYATOB This muscle arises from the apex of the petrous 
 
 PALATI. portion of the temporal bone and from the under 
 
 part of 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. 34). Its 
 action is to raise the soft palate, so as to make it horizontal in 
 deglutition. It is supplied by a nerve from the spheno-palatine 
 ganglion. 
 
 This muscle is situated between the internal 
 pterygoid m. and the internal pterygoid plate of 
 the sphenoid bone. It arises from the scaphoid fossa of the 
 sphenoid bone, and from the outer side of the cartilage of the 
 Eustachian tube. Thence it descends 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. Its nerve is derived from the 
 otic ganglion, and enters the muscle on its inner aspect. 
 
 AZTGOS OR This consists of two thin bundles of muscular 
 
 LETATOB UVULJK. fibres situated one on each side of the middle line. 
 It arises from the aponeurosis of the palate and descends along 
 the uvula nearly down to its extremity. It receives its nerve from 
 the spheno-palatine ganglion. 
 
 PALATO-GLOSSCS These muscles are contained within the arches 
 AND PAIATO- of the soft palate. The palato-glossus, within 
 
 PHAKYNGEUS. foe anterior arch, proceeds from the anterior 
 
 surface of the soft palate to the side of the tongue, and is lost in 
 the stylo-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. As it descends its 
 fibres spread out and, passing along the side of the pharynx, blend 
 .with the fibres of the inferior constrictor and the stylo-pharyngeus. 
 
186 TONSILS. EUSTACHIAN TUBE. 
 
 Both these muscles are supplied by the descending palatine branches 
 of the spheno- palatine ganglion. 
 
 The tonsils are situated at the entrance of the 
 fauces, between the arches of the soft palate. 
 Their use is to lubricate the fauces during tbe passage of the food. 
 On their inner surface are visible from twelve to fifteen orifices 
 leading into crypts which make the tonsil appear 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 fluid secreted by these cells is viscid and transparent, in the 
 healthy state : but it 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. 
 
 The tonsil 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 instrument should never be directed outwards, 
 but inwards towards the mesial line.* The tonsil is supplied 
 with blood by the tonsillar and palatine branches of the facial, 
 and by the descending palatine branch of the internal maxillary. 
 Nerves are furnished to it from the glosso-pharyngeal. 
 
 EUSTACHIAN This canal conveys air from the pharynx to the 
 
 TuBE - tympanum of the ear. Its orifice is situated 
 
 opposite the back part of the inferior spongy bone. The direc- 
 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 
 
 * Cases are related by Portal and B^clard, in which the carotid artery was 
 punctured in opening an abscess in the tonsil. The result was immediately fatal 
 haemorrhage. 
 
HARD PALATE. 187* 
 
 composed of fibro-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- 
 cartilage bounds it only on the inner and the upper part of the 
 circumference ; the integrity of the canal below 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. 
 That which lines the cartilaginous portion of the tube is thick 
 and vascular, and gradually becomes thinner towards the tympanum. 
 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, and are similar 
 in nature and function to the glands beneath the mucous mem- 
 brane of the mouth, the palate, and the pharynx. 
 
 The hard palate, formed by the superior maxil- 
 HARD PALATE 
 
 lary and palate bones, is a resisting surface for the 
 
 tongue in tasting, in mastication, in deglutition, and in the arti- 
 culation 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 per- 
 forated in syphilitic disease. 
 
 A thick layer of glands (glandulce palatines] 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 
 visible to the naked eye. The mucous membrane has a very 
 thick epithelial coat, which gives the white colour to the palate;. 
 
188 MECHANISM OF DEGLUTITION. 
 
 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 OF With the anatomy of the parts fresh in your 
 
 DEGLUTITION. mind, consider for a moment the mechanism of 
 
 deglutition. 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 (by the 
 stylo-pharyngei on each side).* The food, having reached the 
 pharynx, is prevented from ascending into the nasal passages by 
 the approximation of the posterior palatine arches, and the eleva- 
 tion 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 compressed by the con- 
 strictors of the pharynx, the food passes into the oesophagus, 
 through which it is conveyed into the stomach by the undulatory 
 contraction of that tube. 
 
 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, as the air-tube must be closed 
 while the food passes over it, and 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 distension of the pharynx. 
 
 t 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 mechanism, 
 
DISSECTION OP THE LARYNX. 189 
 
 DISSECTION OF THE LAKYNX. 
 
 SITUATION AND The larynx is the upper part of the air-passage, 
 
 RELATIONS. jn which vocalisation takes place. It is a com- 
 
 plicated apparatus consisting of numerous cartilages articulated 
 together to form an open tube. 
 
 It forms a prominence in the middle line of the neck, covered 
 in front by the integument and cervical fascia, the sterno-hyoid, 
 sterno-thyroid, and thyro-hyoid muscles and the thyroid body. 
 It has the great vessels of the neck on each side. Above, it is 
 attached to the hyoid bone ; below, it is continuous with the 
 trachea ; behind it, is the pharynx, into which it opens. 
 
 Before commencing the dissection of the larynx, the student 
 should make himself acquainted with the cartilages which compose 
 it, and the ligaments which connect them, as seen in a dry pre- 
 paration. 
 
 This bone, named from its resemblance to the 
 Greek 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 consists of 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 attachments 
 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 
 fibre-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 with synovial membrane, which admits of free 
 motion. They are of the size of a barley-corn, and give attachment 
 to the stylo-hyoid ligaments. 
 
190 DISSECTION OF THE LAEYNX. 
 
 The os hyoides is connected with the thyroid 
 cartilage by several ligaments, which contain a 
 quantity of elastic tissue. There is : 1. The thyro-hyoid mem- 
 brane, which proceeds from the superior border of the thyroid 
 cartilage to the upper and posterior part of the hyoid bone. In 
 front of this membrane there is 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, and is 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 
 extend between the extremities of the greater cornua of the 
 os hyoides, and the ascending cornua of the" thyroid cartilage. 
 They often contain a small nodule of cartilage, cartilago triticea. 
 
 CARTILAGES OF The framework of the larynx is composed of 
 
 THE LABTNX. n i ne cartilages viz., the thyroid, the cricoid, the 
 
 two arytenoid, the two cornicula laryngis, the two cuneiform 
 cartilages and the epiglottis. These are connected by joints and 
 elastic ligaments, so that they can be moved upon each other by 
 their respective muscles ; the object of this motion being to act 
 upon two elastic ligaments called the vocal cords, upon the vibra- 
 tion of which phonation depends. 
 
 THTEOID CAR- This cartilage, so called because it shields the 
 
 TILAGE - mechanism behind it,* consists of two lateral 
 
 halves, alee, united at an acute angle in front, which forms the 
 prominence termed the 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. Each 
 ala is somewhat quadrilateral in form, and presents for examina- 
 tion two surfaces and four borders. The outer surface of each ala 
 is marked by an oblique line passing downwards and forwards from 
 the upper cornu, which gives attachment to the sterno-thyroid and 
 thyro-hyoid muscles. The smooth surface behind the ridge, gives 
 attachment to the inferior constrictor. The inferior border is 
 slightly arched in the middle, and on either side presents a convex 
 
 * Qvpebs, a shield. 
 
DISSECTION OF THE LARYNX. 191 
 
 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. 
 
 CRICOID CAR- This cartilage, named from its resemblance to 
 
 TILAGE. a ring,* is 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 an inch in vertical depth, and occupies part of the interval 
 left between the alse of the thyroid. In the middle of 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 : to the lower part of the vertical ridge are attached some 
 of the longitudinal fibres of the oesophagus. 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 outer surface, external to the depression for the crico- 
 arytenoideus posticus, is an elevated facet which articulates with 
 the inferior cornu of the thyroid cartilage. In front of this 
 articular surface it gives attachment to the inferior constrictor of 
 the pharynx. The lower border is connected by elastic membrane 
 to the first ring of the trachea. The inner surface is smooth, and 
 the upper border is elliptical ; its lower being nearly circular. 
 
 The thyroid cartilage is connected to the cricoid 
 by a membrane the crico-thyroid. It consists of 
 a median triangular portion composed mainly of elastic tissue, with 
 its base directed upwards. The lateral portions are thin and 
 membranous, extending as far backwards as the articular facets 
 for the thyroid cartilage, and are intimately connected with the 
 inferior vocal cords. Between the inferior cornu of the thyroid 
 
 * Kpi/cos, a ring. 
 
192 DISSECTION OF THE LARYNX. 
 
 cartilage and the cricoid there is a distinct joint, having a synovial 
 membrane, and strengthened by a capsular ligament. The articu- 
 lation allows of a movement revolving upon its own axis, and, 
 consequently, permits the approximation of the two cartilages. 
 
 ARYTENOID These cartilages are situated, one on each side, 
 
 CARTILAGES. a t the back of the cricoid cartilage. In the 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, and is about 
 five or six lines in height, and three lines in diameter at its base. 
 The posterior' surface of each is triangular and concave, and gives 
 attachment to the arytenoideus muscle : the anterior surface is 
 irregular and convex, affording attachment to the thyro-arytenoi- 
 deus, and to the superior or false vocal cord : the internal surface, 
 the narrowest and nearly flat, faces the corresponding surface of 
 the opposite cartilage, and is covered with mucous membrane. 
 The base is broad, and presents a smooth somewhat triangular 
 surface which articulates with the cricoid cartilage : in front of the 
 base is the pointed anterior angle, 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 the 
 external angle, into which certain muscles moving the cartilage 
 are inserted : viz. the crico-arytenoideus posticus and crico-aryte- 
 noideus lateralis. The base is articulated with the cricoid by a 
 joint which has a loose capsular ligament and a synovial mem- 
 brane, permitting motion in all directions, like the first joint of 
 the thumb. The apex is truncated and points backwards and 
 inwards. It is surmounted by a cartilaginous nodule, called the 
 corniculum laryngis. 
 
 CUNEIFORM These cartilages, sometimes calleTl the cartilages 
 
 CARTILAGKS. o f Wrisberg, are conical in form, and somewhat 
 
 curved, with their broader part directed upwards and forwards. 
 They are contained in the aryteno-epiglottidean fold. 
 
 This piece of yellow fibro-cartilage is situated in 
 the middle line, and projects over the larynx like 
 
 * Apvraiva, & ewer. 
 
DISSECTION OF THE LARYNX. 193 
 
 a valve. It is like a leaf with its stalk directed downwards. Its 
 ordinary position is perpendicular, leaving the upper opening of 
 the larynx free for respiration; but during the elevation of the 
 larynx in deglutition it becomes horizontal, falls downwards and 
 backwards over the larynx, and prevents the entrance of food into 
 it. This descent 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 at- 
 tached by the thyro-epiglottic ligament to the angle of the thyroid 
 cartilage; it is also connected by an elastic ligament, hyo-epi- 
 glottic, to the os hyoides. Laterally its borders are rather turned 
 backwards, and to them are attached two folds of mucous mem- 
 brane which pass to the arytenoid cartilages, called the aryteno- 
 epiglottic folds. Its anterior surface is only free at its base, 
 where it is connected with the base of the tongue by the three glosso- 
 epiglottic folds. Its posterior or laryngeal surface is concavo- 
 convex and free, and looks towards the larynx. The surface of the 
 epiglottis is closely invested by mucous membrane ; this being re- 
 moved, the yellow cartilage of the epiglottis is seen pitted and 
 often perforated by the small muciparous glands. 
 
 The cartilages of the larynx resemble those of the ribs in struc- 
 ture. In the young they are dense and elastic, but some 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, cornicula laryngis 
 and cuneiform cartilages are rarely ossified, on account of their, 
 composition, which resembles that of the ear and the nose. 
 
 The larynx must now be examined in its perfect condition. 
 Mucous MEM- Except on the true vocal cords and the epiglottis, 
 
 BRANB OF THE the mucous membrane of the larynx presents a 
 
 LARYNX. wrinkled appearance, and is loosely connected to the 
 
 subjacent structures by an abundance of fibre-cellular tissue, which 
 admits of its being elevated 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 
 
 
 
194 DISSECTION OF THE LARYNX. 
 
 symptoms of suffocation. From the root of the tongue to the 
 anterior surface of the epiglottis, the membrane forms three folds, 
 glosso-epiglottw, one median, and two lateral, containing elastic 
 tissue. From the epiglottis, to which it is intimately adherent, it 
 is continued backwards on either side to the apices of the ary- 
 tenoid cartilages, forming the aryteno-epiglottic 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 upper opening of 
 the larynx during the passage of the food over it. The larynx is 
 closed during the act of deglutition; but if, during this process, 
 anyone attempt to speak or laugh, the epiglottis is raised, and 
 allows the food to pass, 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-epiglottic fold, 
 and they are particularly numerous about the ventricles of thelarynx. 
 The surface of the epiglottis towards the tongue is abundantly pro- 
 vided with them. Their ducts pass through the epiglottis, and 
 may be recognised as minute openings on its laryngeal aspect. 
 
 SUPERIOR This is the opening through which the larynx 
 
 OPENING OF THE communicates with the pharynx. Its outline is 
 LARYNX. triangular, with its base directed forwards, and it 
 
 slopes from before backwards. Anteriorly it is bounded by the 
 epiglottis, laterally by the aryteno-epiglottic folds and cuneiform 
 cartilages, posteriorly by the arytenoid cartilages and the corni- 
 cula laryngis. The apex presents the funnel-shape appearance 
 from which the arytenoid cartilages derive their name. 
 
 INFERIOR Look down into the larynx and observe the 
 
 OPENING OF THE triangular horizontal opening in the middle line ; 
 LARYNX, OR EIMA this is the rima glottidis or glottis. Its apex is 
 GLOTTIDIS. directed forwards, its base backwards. The an- 
 
 terior two-thirds of this opening is bounded by the inferior or true 
 
DISSECTION OF THE LARYNX. 195 
 
 vocal cords, the posterior third by the arytenoid 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, leading into a pouch 
 called the sacculus laryngis, which ascends for a short distance 
 and terminates in a cul-de-sac by the side of the thyroid cartilage. 
 In the middle line below the base of the epiglottis is seen a 
 round elevation covered with mucous membrane of a bright red 
 colour : this is termed the cushion of the epiglottis. The length 
 of the rima glottidis in the male is eleven lines ; its width at rest 
 from three to four lines ; in the female its length is eight lines, 
 its width two lines. 
 
 STTPEBIOB OR These are the prominent crescentic folds which 
 
 FALSE VOCAL form the upper boundaries of the ventricles. 
 
 COEDS. 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. 
 
 INFERIOR OB These two cords, composed of elastic tissue, and 
 
 TBUE VOCAL covered with very thin and closely adherent mu- 
 
 CoBDS - cous membrane, extend horizontally from the 
 
 angle of the thyroid cartilage- to Fio g . 
 
 the base of each of the arytenoid. 
 
 They diverge as they pass back- //ii^\\ Thyroid cartilage. 
 
 wards ; the space between them is // \\ Tmc yocai cord. 
 
 called the rima glottidis. We 
 shall presently see that, by the 
 muscles which act upon the ary- 
 tenoid cartilages, these cords can /I V "^~ Arytenoid cartilage ' 
 be approximated or separated (^J^ ^~^ Elastic ll sment - 
 from each other; in other words, 
 the rima glottidis can be closed SHAPE OF THE GLOTTIS 
 
 J-1 L J A*71_ C .LI WHEN AT EZST - 
 
 or dilated. When sufficiently 
 
 tightened, and brought parallel by means of certain muscles, the 
 cords are made to vibrate by the current of the expired air, and 
 thus is produced the voice. 
 
 o 2 
 
196 DISSECTION OP THE LARYNX. 
 
 In the adult male the true vocal cords measure about seven 
 lines ; in the female about five lines. In boys they are shorter ; 
 hence their peculiar voice. At puberty, the cords lengthen, 
 and the voice breaks. The free edges of the true vocal cords 
 are thin and sharp, and look somewhat upwards; this may be 
 demonstrated by making a vertical transverse section through 
 them. 
 
 The glottis admits of being dilated, contracted, and even com- 
 pletely closed by its appropriate muscles. When at rest, its shape 
 is triangular, as shown in fig. 35, 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. 37). 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. 35, 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 
 speaking or singing, the glottis assumes what is called the vocal- 
 ising position that ;is, the opening becomes narrower and its 
 edges nearly parallel. 
 
 VENTRICLES OF These are the hollows between the upper and 
 THE LARYNX. lower vocal cords, and each leads to a small pouch, 
 
 the sacculus laryngis. Each ascends for about half an inch as 
 high as the upper border of the thyroid cartilage, which bounds it 
 on its outer side, while on the inner side is the upper vocal cord. 
 It contains from sixty to seven ty^muciparous glands. Over its 
 inner and upper part is a layer of muscular tissue, compressor 
 sacculi laryngis of Hilton, which connects it with the aryteno- 
 epiglottic fold. 
 
 INTRINSIC There are eleven muscles which act upon the 
 
 MUSCLES OF THH larynx : five on each side and one in the middle. 
 LARYNX. f^g fi ve p a i rs are the crico-thyroidei, the crico- 
 
 arytenoidei postici, the crico-arytenoidei laterales, the thyro-ary- 
 tenoidei, and the aryteno-epiglottidei. The single one is the 
 arytenoideus. 
 
DISSECTION OP THE LAKYNX. 
 
 197 
 
 M. CHICO- This muscle is situated on the front of the 
 
 THTEOIDEUS. larynx. It arises from the side of the cricoid 
 
 cartilage, ascends obliquely outwards, and is inserted into the 
 inferior border and lower cornu of the thyroid. Its action is to 
 tigthen the vocal cords. It does this by depressing the thyroid 
 cartilage : since this cartilage cannot be depressed without length- 
 ening these cords, as shown by the dotted line, fig. 36. Its nerve 
 is the external laryngeal branch of the superior laryngeal. Be- 
 tween the anterior borders of the two muscles is seen the crico- 
 thyroid membrane, which is divided in Laryngotomy. 
 
 FIG. 36. 
 
 Arytenoid cartilage . 
 Crico-arytenoid joint 
 
 Crico-thyroid joint . 
 
 Thyroid cartilage. 
 
 Thyroid cartilage depressed. 
 
 True vocal cord. 
 
 True vocal cord stretched. 
 
 Crico-thyroid muscle. 
 Cricoid cartilage. 
 
 DlAGBAM SHOWING THE ACTION OF THE CHICO-THYBOID MUSCLE. 
 
 M. CEICO- 
 
 AEYTENOIDEUS 
 POSTICUS. 
 
 This muscle arises from the posterior part of 
 the cricoid cartilage r its fibres converge and 
 pass outwards and upwards, to be inserted into, 
 the outer angle of the arytenoid. Its- action is to dilate the 
 glottis. It does this by drawing the posterior tubercle of the 
 arytenoid cartilage towards the mesial line, and therefore the 
 anterior angle (to which the vocal cord is attached) from the 
 mesial line (fig. 37). 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 
 
198 
 
 DISSECTION OF THE LARYNX. 
 
 and the weight. This muscle dilates the glottis at each inspira- 
 tion. Its nerve comes from the inferior laryngeal. 
 
 M. AKYTE- This single muscle is situated immediately at 
 
 NOIDEUS. the back of the arytenoid cartiiages. The fibres 
 
 pass across from one cartilage to the other running in a transverse 
 direction. Action. By approximating the arytenoid cartilages, 
 they assist in contracting the glottis. It is supplied by the inferior 
 laryngeal nerve. 
 
 M. ABYTENO- This muscle ari-ses from the outer angle of the 
 
 EPIGLOTTIDEUS. arytenoid cartilage and, crossing its fellow like 
 
 FIG. 37. 
 
 Vocal cord .... 
 Thyroid cartilage . 
 Cricoid cartilage . . 
 
 Arytenoid cartilage . . 
 
 Elastic ligament (crico- 
 
 arytenoid) . . . . 
 
 Thyro-arytenoideu. . 
 
 Crico-arytenoideus la- 
 teralis. 
 
 Ideal pivot. 
 
 Crico-arytenoideus pos- 
 ticus. 
 
 GLOTTIS DILATED. MUSCLES DILATING IT BEPBESENTED WAVY. 
 
 the letter X, is inserted, partly into the apex of the opposite 
 arytenoid cartilage, and partly into the aryteno-epiglottidean fold. 
 M. Gmco- To expose this muscle, cut away the ala of the 
 
 ABYTENOIDEU3 thyroid cartilage. It arises from the upper 
 LATEKALIS. border of the side of the cricoid cartilage, and is 
 
 inserted into the external angle of the base of the arytenoid in 
 front of the erieo-arytenoideus posticus. Action. By drawing 
 the arytenoid cartilages inwards, the muscles of opposite sides 
 contract the glottis (fig. 38). Its nerve comes from the inferior 
 laryngeal. 
 
DISSECTION OP THE LAETNX. 
 
 199 
 
 M. THTKO- This muscle arises from the angle of the 
 
 ABYTENOIDEUS. thyroid cartilage and the crico-thyroid membrane, 
 runs horizontally 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. Its 
 nerve comes 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 margins of the glottis are parallel, and the chink is reduced to 
 the breadth of a shilling. 
 
 FIG. 38. 
 
 Vocal cord 
 
 Arytenoid cartilage 
 Elastic ligament . 
 
 Thyro-arytenoideus. 
 
 Crico-arytenoidens la- 
 teralis. 
 
 Crico-arytenoideus pos- 
 ticus. 
 
 GLOTTIS CLOSED. MUSCLES CLOSING IT BKPEESENTED WATT. 
 
 The following table shows the action of the several muscles 
 which act upon the glottis : 
 
 Crico-thyroidei . 
 Thyro-arytenoidei ; 
 
 Crico-arytenoidei postici 
 Crico-arytenoidei laterales 
 
 Arytenoideus 
 Aryteno-epiglottidei 
 
 Stretch the vocal cords. 
 
 Relax the vocal cords, and place them in the 
 
 vocalising position. 
 Dilate the glottis. 
 Draw together the arytenoid \ , , 
 
 cartilages [ , ... 
 
 glottis. 
 Ditto ditto ditto ) 
 
 Contract the upper opening of the larynx. 
 
 The blood-vessels of the larynx are derived from the superior 
 
200 MSSECTION OF THE LARYNX. 
 
 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 little artery passes through the crico-thyroid mem- 
 brane. - 
 
 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 inferior 
 laryngeal. Its external laryngeal branch supplies the crico-thyroid 
 muscle. 
 
 The inferior (or 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 
 moving the glottis become paralysed, but its sensibility remains 
 unimpaired. When the nerve is compressed by a tumour for 
 instance, an aneurysm of the arch of the aorta the voice is 
 changed to a whisper,* or even lost. 
 
 DIFFERENCE BE- Until the approach of puberty, there is no great 
 
 TM'EEN THE MALE difference in the relative size of the male and 
 
 AND THE FEMALE female larynx. The larynx of the male, within 
 
 two years after this time, becomes nearly doubled 
 
 in size ; that of the female grows, 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 
 * ' Medical Gazette,' Dec. 1843. 
 
DISSECTION OP THE TONGUE. 201 
 
 the male ; hence the greater projection of the ' pomum Adami,' 
 and the greater length of the vocal cords, in the male. 
 
 i ^1 f^ ^ 3 j.\. (Male . , 7 lines. 
 
 The average length of the vocal cords is in the J 
 
 (Female . 5 lines. 
 
 The average length of the glottis is in the . J a e ' ' . . 
 
 {Female . 8 lines. 
 
 The size of the larynx does not necessarily follow the propor- 
 tions 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. 
 
 CEICO-THTKOID This joint is provided with a capsule and synovial 
 AETICULATION. membrane. There are, besides, two strong liga- 
 ments. Both proceed from the cornu of the thyroid cartilage ; 
 the one upwards and backwards, the other downwards and forwards 
 to the cricoid. Remember 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. Its upper surface 
 is convex and free, as is also its anterior part or tip which lies 
 behind the lower incisor teeth ; its posterior and inferior part is 
 connected to the os hyoides by the hyo-glossi, to the styloid process 
 of the temporal bone by the stylo-glossi, and to the symphysis of 
 the lower jaw by the genio -hyo-glossi muscles. 
 
 Its upper surface, or dorsum, is convex, and slopes on all sides 
 from the centre : running along the middle is a median groove 
 raphe which terminates posteriorly in a depression, the foramen 
 ccecum, into which open several mucous glands. 
 
 The surface of the tongue is covered with mucous membrane, 
 which is composed of structures similar to those of the skin 
 generally : that is to say, it consists of a ' cutis vera,' with nume- 
 rous elevations called papillae, and of a thick layer of squamous 
 
202 DISSECTION OP THE TONGUE. 
 
 epithelium. The cutis is much thinner than that of the skin of the 
 body, and affords insertion to some muscular fibres of the tongue. 
 
 The mucous membrane on the under aspect of the tongue is 
 smooth and comparatively thin, and, in the middle line in front, 
 forms a fold the frcenum linguce which connects it to the 
 mucous membrane of the floor of the mouth. Laterally the 
 mucous membrane is reflected from the under part of the tongue 
 to the lower jaw, and forms the floor of the mouth. 
 
 From the posterior part of the tongue the mucous membrane 
 passes to the soft palate on each side, forming the folds termed the 
 anterior palatine arches, which enclose the palato-glossi ; there are 
 also three folds to the epiglottis, termed the glosso-epiglottic : two 
 lateral and one median, the latter enclosing a layer of elastic tissue, 
 called the glosso-epiglottic ligament. This ligament raises the 
 epiglottis when the tongue is protruded from the mouth ; hence the 
 rule of never pulling the tongue forwards when passing a tube 
 into the oesophagus, otherwise the tube might pass into the 
 larynx. 
 
 PAPILLA OF The anterior two-thirds of the tongue are 
 
 THE TONGUE. studded with numerous small eminences, called 
 
 papillce ; these, according to their size and form, are distinguished 
 into three kinds viz. papillce circumvallatce, papillce fungi- 
 formce, and papillce filiformce (fig. 39). 
 
 The papillce circumvallatce vary in number from eight to twelve, 
 and 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 foramen caecum. Each of these papillae is circular, 
 from the -^th to -^th of an inch wide, and slightly broader above 
 than below. Each is surrounded by a circular fossa, which itself 
 is bounded by an elevated ring. The papillae are covered with a 
 thick stratum of scaly epithelium, beneath which are numerous 
 secondary papillae. Buried in the epithelium on the side (but not 
 on the upper surface) of these papillae, numerous flask-shaped 
 bodies, called the taste buds, have been discovered. Their bases 
 rest upon the deeper structures, and their apices open upon the 
 surface. According to recent authorities they are in close con- 
 
DISSECTION OF THE TONGUE. 
 
 203 
 
 nection with the ultimate distribution of the glosso-pharyngeal 
 nerve.* 
 
 The papilla; fungiformce, smaller and more numerous than 
 the drcumvallatce, are scattered chiefly over the sides and tip of 
 the tongue, and sparingly over its upper FIG. 39. 
 
 surface. They vary in shape, some being 
 cylindrical, others having rounded heads like 
 mushrooms; whence their name. Near the 
 apex of the tongue they may be distin- 
 guished during life from the other papillae 
 by their redder colour. In scarlatina, and 
 some exanthematous fevers, these papillae 
 become elongated, and of a bright red colour : 
 as the fever subsides, their points acquire a 
 brownish 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 
 
 UPPER SURFACE OF THE 
 
 smooth if the finger be passed over it from TONGUE ' WITH THE FAUCES 
 
 AND TONSILS. 
 
 1. Papillae circumvallataa. 
 
 2. Papillae fungiformae. 
 
 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 hairlike 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 
 
 * For further information about these bodies the student is referred to Engelman- 
 Stracker's ' Handbook.' 
 
204 DISSECTION OF THE TONGUE. 
 
 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. 
 
 The papillae are covered with one or more layers of squamous 
 epithelium. That which covers the filiform is superimposed so 
 thickly as to give it sometimes the appearance of a brush when 
 seen under the microscope. The various kinds of fur on the 
 tongue consist of thick and sodden epithelium. 
 
 Respecting the use of the papillae, it i& probable that they 
 enable the tongue to detect impressions with greater delicacy. 
 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 papillae 
 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 racemose 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. 
 
 GLANDS BE- O n the under surface of the apex of the tongue 
 
 NEATH THE APEX is placed, on either side, a group of glands pre- 
 OF THE TONGUE. sumed to be 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 
 * See Bowman and Todd's ' Physiological Anatomy.' 
 
DISSECTION OP THE TONGUE. 205 
 
 fibres of the stylo-glossus. Four or five ducts proceed from each 
 group, and terminate by separate orifices on the under surface of 
 the tongue. 
 
 MUSCULAR The substance of the torrgue is composed of 
 
 FIBRES OF THE muscular fibres and of a small quantity of fat. 
 TONGUE. "j^g extrinsic muscles of the tongue have been 
 
 described in the dissection of the submaxillary region (p. 47). 
 We have now to examine its intrinsic muscles. For this purpose 
 the mucous membrane must be removed from the dorsum 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 linguales muscles. 
 
 The superior lingualis runs longitudinally beneath the mucous 
 membrane of the dorsum; its fibres are attached posteriorly to 
 the hyoid bone and run forwards to the front and margin of 
 the tongue. Posteriorly the muscle is thin and is covered by the 
 fibres of the palato-glossus and hyo-glossus. 
 
 The inferior lingualis is larger than the preceding, and is 
 situated on the under aspect of the tongue between the genio-hyo- 
 glossus and the hyo-glossus. It may be readily exposed by dis- 
 secting the under surface of the tongue immediately on the outer 
 aspect of the genio-hyo-glossus. It arises posteriorly from the 
 hyoid bone and the substance of the tongue, and its fibres pass 
 forwards to the tip of the tongue after being reinforced by fibres 
 from the stylo-glossus. 
 
 The transverse fibres form a considerable part of the thickness 
 of the tongue and arise from the fibrous septum. They pass out- 
 wards between the superior and inferior linguales, ascending as 
 they near the sides of the tongue where the fibres become con- 
 tinuous with those of the palato-glossus. A considerable amount 
 of fat is found among these fibres. 
 
 The vertical fibres run in a curved direction, descending from 
 the dorsum to the under aspect of the tongue, with the concavity 
 outwards. They interlace with the transverse fibres and with the 
 genio-hyo-glossus . 
 
 On tracing the genio-hyo-glossi into the tongue, we find that 
 
206 DISSECTION OP THE ORBIT. 
 
 some of their fibres ascend directly to the surface; others cross 
 in the middle line, intersect the longitudinal fibres and finally ter- 
 minate upon the sides of the tongue. Lastly, the fibres of the 
 stylo-glossi should be traced along the side of the tongue to the 
 apex. 
 
 FIBROUS SEPTUM The fibrous septum of the tongue is a vertical 
 OF THE TONGUE. plane of fibrous tissue which extends, in the 
 mesial line, from the base to the apex. It is connected behind with 
 the hyoid bone, and lost in front between the muscles. In it is some- 
 times found a piece of fibro- cartilage, called nucleus fibrosus 
 linguae, a representative of the lingual bone in some of the lower 
 animals. 
 
 The arteries supplying the tongue are the dorsal and ranine 
 branches of the lingual artery (p. 52). 
 
 The nerves to the tongue should now be followed to their 
 termination. The hypoglossal supplies with motor power all the 
 muscles. The gustatory or lingual branch of the inferior division 
 of the fifth is distributed to the mucous membrane and papillae of 
 the apex and sides of the tongue, supplying the anterior two- 
 thirds with common sensation. 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 the sides of the tongue, and the papilte circum- 
 vallatse. Under the microscope small ganglia may be distinguished 
 on the terminal fibres of this nerve. 
 
 DISSECTION OF THE OKBIT. 
 
 To expose the contents of the orbit, remove that portion of the 
 orbital plate which forms the roof of the orbit as far back as the 
 optic foramen, making one section on the outer side, 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 turned forwards and downwards, 
 
DISSECTION OF THE ORBIT. 
 
 207 
 
 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. 
 
 PEEIOSTEUM OF The roof being removed, we expose the fibrous 
 THE ORBIT. membrane, which lines the walls of the orbit. It 
 
 is a continuation 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 ligament which fixes 
 the tarsal cartilage. 
 
 FIG. 40. 
 
 DIAGRAM OF THE NERVES OF THE ORBIT. 
 
 FASCIA OF The fascia of the orbit serves the same purpose 
 
 THE ORBIT. 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, where it passes from one rectus muscle to the 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, and the optic nerve, and separates the eye from the fat 
 at the bottom of the orbit. 
 
208 DISSECTION OP THE CEBIT. 
 
 CONTENTS OF There are six muscles to move the eye ; four of 
 
 THE OBBIT. which, running in a straight direction, are called 
 
 the 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. 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 first or ophthalmic division 
 of the fifth divides into a frontal, lachrymal, and nasal branch. 
 The orbit contains, also, a quantity of fat, which forms a soft 
 bed for the eye and prevents it from being retracted too far by 
 its muscles. Upon the quantity of this fat depends, in some 
 measure, the prominence of the eyes. Its absorption in disease 
 or old age occasions the sinking of the eyeballs. The eye is 
 separated from the fat by a fold of the orbital fascia, which, like 
 a tunica vaginalis, enables the globe to move with 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 should be carefully traced. In the middle 
 are seen the frontal nerve and artery, lying upon the, levator 
 palpebrse ; on the inner side is the fourth nerve lying on and 
 supplying the superior oblique ; on the outer side, the lachrymal 
 nerve and artery pass forwards to the lachrymal gland, which lies 
 under cover of the external angular process. 
 
 The ophthalmic or first division, of the fifth nerve, after giving 
 off from its inner side, while within the cavernous sinus, the nasal 
 nerve, divides into the lachrymal and frontal nerves, of which the 
 FRONTAL latter is the larger. The frontal nerve runs for- 
 
 NERVE. wards upon the upper surface of the levator 
 
 palpebrse, on which, about midway in the orbit, it divides into two 
 branches, the supra-trochlear and the supra-orbital. 
 
 a. The supra-trochlear runs obliquely inwards above the pulley of 
 
LACHRYMAL GLAND. 209 
 
 the superior oblique to the inner angle of the orbit. Here it gives off 
 a small communication to the infra-trochlear branch of the nasal, and 
 then divides, after passing between the bone and the orbicularis palpe- 
 brarum, into filaments which supply the skin of the upper eyelid, forehead, 
 and nose. One or two small filaments may be traced through the bone 
 to the mucous membrane of the frontal sinuses.* 
 
 b. The supra-orbital is the continuation of the frontal nerve, and 
 runs forwards to the supra-orbital notch, through which it ascends to 
 supply the skin of the upper eyelid, forehead, and scalp. Its cutaneous 
 branches, an inner and an outer, which run upwards beneath the 
 occipito-frontalis, have been described in the dissection of the scalp 
 (p. 4). 
 
 LACHRYMAL This is the smallest of the three branches of the 
 
 NEBVE. ophthalmic nerve. It runs along the outer side 
 
 of the orbit with the lachrymal artery, through the lachrymal gland, 
 which it supplies as well as the upper eyelid. Its branches within 
 the orbit are : 1, a branch which passes down behind the lachry- 
 mal gland to communicate with the orbital branch of the superior 
 maxillary nerve ; 2, filaments to the lachrymal gland. It then 
 pierces the palpebral ligament to supply the skin of the upper 
 eyelid. 
 
 FOURTH CEA- This nerve enters the orbit through the sphe- 
 
 NIAL NERVE. noidal fissure above the other nerves. It runs 
 
 along the inner side of the frontal nerve, and enters the 
 orbital surface of the superior oblique, to which it is solely dis- 
 tributed.f 
 
 LACHRYMAL This gland is situated below the external 
 
 GLAND. angular process 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 separated from the rest, close to the back part of the 
 upper eyelid, and is covered by the conjunctiva. The whole 
 
 * These filaments have been described by Blumenbach ' De sinibus Frontal.' 
 f This nerve is joined in the outer wall of the cavernous sinus by filaments from 
 
 the sympathetic. Here also it sends backwards two or more filaments to supply the 
 
 tentorium cerebelli. 
 
210 
 
 LACHETMAL GLAND. 
 
 FIG. 41. 
 
 gland is invested by a capsule * formed by the fascia of the 
 orbit. 
 
 The lachrymal gland consists of an aggregation of small lobes 
 composed of smaller lobules, connected by fibre-cellular tissue, 
 
 and resembles the structure of the 
 salivary glands. 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. 41). 
 They are not easily discovered in 
 the human eye ; 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 saps 
 forwards, like ribands, to their insertions. 
 
 LEVATOB This muscle arises from the roof of the orbit, 
 
 PALPEBRJE. above and in front of the optic foramen. It 
 
 gradually 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 
 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 or 
 ocular aspect. . 
 
 * This capsule, being a little stronger on the under surface of the gland, is de- 
 scribed and figured by Scemmerring as a distinct ligament, ' Icones Oculi Humani,' 
 tab. vii. 
 
MUSCLES IN THE ORBIT. 211 
 
 OBLIQUUS This muscle arises from the inner side of the 
 
 SCPEHIOB. foramen opticum. It runs along the inner side 
 
 of the orbit, and terminates in a round tendon, which passes through 
 a cartilaginous pulley trochlea 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 sclerotic coat, 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 will be considered with 
 that of the inferior oblique (p. 217). It is supplied by the fourth 
 nerve, which enters the back part of its upper surface. 
 
 The frontal nerve and levator palpebrae should now be cut 
 through the middle and reflected, to expose the superior rectus 
 muscle. 
 
 FOUB RECTI These four muscles have a tendinous origin 
 
 MUSCLES. round the foramen opticum, so that, collectively, 
 
 they embrace the optic nerve. They diverge from each other, one 
 above, one below, and one on each side of the optic nerve ; and 
 are named, accordingly, rvctus superior, inferior, externus, and 
 internus. Their broad thin tendons are inserted into the sclerotic 
 coat of the eye, about a quarter of an inch from the margin of 
 the cornea (fig. 42). 
 
 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. 
 
 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. 
 
 p 2 
 
212 
 
 MUSCLES IN THE ORBIT. 
 
 Fig. 42. 
 
 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 capsule of Tenon 
 over the back of the eye. This 
 tunic consists of two layers with 
 an intermediate space, lined with 
 flat cells, thus allowing free mo- 
 bility of the globe. It is this 
 fascia which resists the passage of 
 INSERTION OF THE RECTI MUSCLES WITH the hook in the operation for the 
 
 THE ANTEEIOE CILIAET ARTERIES. f ... -,-, /., ,, 
 
 cure oi squinting. Even alter the 
 
 complete division of the tendon, the eye may still be held in its 
 faulty position, if this tissue, instead of possessing its proper 
 softness and pliancy, happen to have become contracted and un- 
 yielding. 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 
 in the background than the rest. The tendon of the internal 
 rectus is nearer to the cornea than either of the others. 
 
NASAL NERVE. 213 
 
 The superior rectus should now be reflected : in doing so, ob- 
 serve 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 obliquely over the optic nerve from without inwards ; 
 3, the inferior division 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 with its ciliary 
 branches; 5, the sixth nerve entering, the ocular aspect of the 
 rectus externus. 
 
 This is one of the three divisions of the oph- 
 thalmic branch of the fifth pair (fig. 40, p. 207). 
 It enters the orbit through the sphenoidal fissure between the two 
 origins of the external rectus, and then crosses obliquely over the 
 optic nerve, beneath the levator palpebrse and the superior rectus, 
 towards the inner wall of the orbit. After giving off the infra- 
 trochlear branch, the nerve passes out of the orbit between the 
 superior oblique and internal rectus, through the anterior ethmoidal 
 foramen, into the cranium, where it lies beneath the dura mater, 
 upon the cribriform plate of the ethmoid bone. It soon leaves the 
 cranium through the nasal 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 con- 
 tinuation of the nerve runs behind the nasal bone, becomes super- 
 ficial 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 (p. 74). 
 
 The nasal nerve gives off the following branches in the orbit : - 
 
 a. One slender filament to the lenticular ganglion (forming its upper 
 or long root) is given off from the nasal nerve as it passes between the 
 heads of the external rectus. It is about half an inch long, and enters 
 the posterior-superior angle of the ganglion. 
 
 b. Two or three long ciliary nerves. They run along the inner side 
 of the optic nerve to the back of the globe of the eye. They are joined 
 
214 OPHTHALMIC AKTEKT. 
 
 by filaments from the lenticular ganglion, 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 branch of the 
 frontal nerve. It then divides into filaments, which supply the skin of 
 the eyelids, the lachrymal sac, the caruncle, and the side of the nose. 
 
 This nerve, having passed through the optic 
 foramen, 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 surrounded by the tendinous origins of the recti; in the rest 
 of its course, by loose fat and by the ciliary nerves and arteries. 
 It is pierced in its course through the orbit by the arteria cen- 
 tralis retina? which runs in the middle of the nerve to the eyeball. 
 OPHTHALMIC This artery arises from the internal carotid. It 
 
 AKTEKT. enters the orbit through the optic foramen, out- 
 
 side the optic nerve; occasionally through the sphenoidal fissure. 
 Its course in the orbit 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 in- 
 ternal angular artery (the terminal branch of the facial). Its 
 branches arise in the following order: 
 
 a. Lachrymal artery, This branch proceeds along the outer wall of 
 the orbit to the lachrymal gland. After supplying the gland, it termi- 
 nates in the upper eyelid. It anastomoses with the deep temporal arte- 
 ries, and with a branch from the arteria meningea media. 
 
 b. Supra-orbital artery. This branch runs forwards with the frontal 
 nerve under the roof of the orbit, and emerges on the forehead threugh 
 the supra-orbital notch. It inosculates chiefly with the superficial tem- 
 poral artery. 
 
 c. Arteria centralis retinae. This small branch enters the optic nerve 
 on the outer aspect, 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 twelve to fifteen in number, and 
 perforate the sclerotic coat at the back of the eye, to supply the choroid 
 
OPHTHALMIC GANGLION. 215 
 
 coat and the iris. They are sometimes called short ciliary, to distin- 
 guish them from the long ciliary, two in number, which run on each 
 side of the optic nerve, enter the sclerotic, and extend horizontally for- 
 wards, one on each side of the globe, between the sclerotic and charoid 
 coats, to the ciliary muscle and iris. The anterior ciliary are branches 
 of the muscular arteries, and proceed with the tendons of the recti, and 
 enter the front part of the sclerotic coat. In inflammation of the iris 
 the vascular zone round the cornea arises from enlargement and conges- 
 tion of the anterior ciliary arteries. 
 
 e. Ethmoidal arteries, Of these arteries, two in number, the anterior 
 and larger passes through the anterior ethmoidal foramen with the nasal 
 nerve ; the posterior enters the posterior ethmoidal foramen. Both give 
 off anterior meningeal branches to the dura mater, and supply the mucous 
 membrane of the nose, and of the ethmoidal cells. 
 
 f. Muscular arteries. These are uncertain in their origin, and give 
 off the anterior ciliary branches. 
 
 g. Palpebral arteries. These branches, a superior and an inferior 
 proceed from the lachrymal, nasal, and supra-orbital arteries, and are dis- 
 tributed to their respective eyelids, forming arches near the margin of the 
 lids between the tarsal cartilages and the orbicularis palpebrarum. 
 
 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 above the tendon of the orbicularis, and inosculates with the angular 
 artery (termination 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 oph- 
 thalmic. It emerges at the inner angle of the eye, ascends, and inoscu- 
 lates with the supra-orbital artery. 
 
 OPHTHALMIC This commences at the inner angle of the eye, 
 
 VEIN ' by a communication with the frontal and angular 
 
 veins. It runs backwards above the optic nerve in a straighter 
 course than the artery, receives corresponding branches, and finally 
 passes between the two heads of the external rectus, to terminate 
 in the cavernous sinus. 
 
 OPHTHALMIC Tm ' s sma11 ganglion (o, fig. 40, p. 207 ), of reddish 
 
 OR LENTICULAR colour, and about the size of a pin's head, is 
 GANGLION. situated at the back part of the orbit, between the 
 
 optic nerve and the external rectus. It receives a sensory branch 
 
216 OPHTHALMIC GANGLION. 
 
 from the nasal nerve, which joins its posterior superior angle; a 
 motor branch (from the lower division of the third), which enters 
 its posterior, inferior angle; and it receives a filament from the 
 sympathetic plexus round the internal carotid artery. The gang- 
 lion thus furnished with motor, sensory, and sympathetic roots, gives 
 off the short ciliary nerves. They run forward very tortuously 
 with the optic nerve, pass through the back of the sclerotic coat, 
 where they are joined by the long ciliary (from the nasal), and are 
 distributed to the iris and the ciliary muscle. Since the ciliary 
 nerves derive their motor influence from the third nerve, the iris 
 must lose its power of contraction when this nerve is paralysed. 
 
 THIRD NERYE, The third nerve, just before it enters the sphe- 
 
 MOTOR OCULI. noidal fissure, 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 palpebrse. 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 (fig. 40). 
 
 What is the result of paralysis of the third nerve? Falling of 
 the upper eyelid (ptosis), external squint, dilatation and immo- 
 bility of the pupil. 
 
 SIXTH NERVE, This nerve enters the orbit between the origins 
 
 MOTOR EXTEBNUS. of the external rectus above the ophthalmic vein, 
 and terminates in fine filaments, which are exclusively distributed 
 to the ocular surface of this muscle. 
 
 Respecting the motor nerves in the orbit, observe that they all 
 enter the ocular surface of the muscles, with the exception of the 
 fourth which enters the orbital surface of the superior oblique. 
 
 INFERIOR This muscle arises by a flat tendon from the 
 
 OBLIQUE. orbital plate of the superior maxilla on the outer 
 
 side of the lachrymal groove. It runs outwards and backwards be- 
 tween the orbit and the inferior rectus, then curves upwards be- 
 tween the globe and the external rectus, and is inserted by a broad 
 thin tendon into the outer and back part of the sclerotic, close to 
 the tendon of the superior oblique. It is supplied by the lower 
 division of the third nerve. 
 
TENSOR TARSI. 217 
 
 ACTION OF THE The action of the oblique muscles of the eye 
 OBLIQUE MUSCLES will be understood if a mark in the iris be watched 
 OF THE EYE. while the head is rotated from side to side on its 
 
 antero-posterior axis. It will be thus seen that the eye does not 
 rotate on its antero-posterior axis, as might have been expected. 
 This is due to the oblique muscles (the right superior acting with 
 the left inferior, and vice versa) which prevent the rotation of the 
 eye on its antero-posterior axis during the movements of the head. 
 In other words, they keep the vertical meridian of the eye always 
 vertical. 
 
 This muscle is onlv a deeper part of the orbi- 
 TENSOR TARSI. 
 
 cularis palpebrarurn. To expose it, cut perpen- 
 dicularly through the middle of the upper and lower lids, and 
 evert the inner halves toward the nose. After removing the 
 mucous membrane, the muscle will be seen arising from the 
 ridge of the lachrymal bone. It passes nearly horizontally out- 
 wards 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 receive 
 the tears at the inner angle of the eye. It is supplied by a small 
 branch from the facial nerve. 
 
 ORBITAL ^^ s * s a ^ wa y s verv sma ll> an d is sometimes 
 
 BRANCH OF THE absent. It comes from the trunk of the superior 
 SUPERIOR MAXIL- maxillary in the spheno-maxillary fossa (fig. 43), 
 LARY NERVE. enters the orbit through the spheno-maxillary fis- 
 
 sure, and divides into two branches. Of these, one, the temporal, lies 
 in a groove in the outer wall of the orbit, and after sending a small 
 branch 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 frequently with the auriculo- 
 temporal branch of the inferior maxillary. The other branch, the 
 malar, passes along the outer part of the floor of the orbit, em- 
 bedded in fat, and makes its exit through a foramen in the malar 
 bone, to supply the skin of the cheek (p. 94). 
 
218 
 
 SUPERIOR MAXILLARY NERVE. 
 
 DISSECTION OF THE SUPERIOR MAXILLARY NERVE. 
 
 To trace this nerve and its branches we must remove the outer 
 wall of the orbit as far as the foramen rotundum, so as to expose 
 the spheno-maxillary fossa. 
 
 The superior maxillary nerve is the second division of the fifth 
 cranial nerve. Proceeding from the Gasserian ganglion (fig. 43), 
 
 FIG. 43. 
 
 Trunk of the 
 fifth nerve . 
 
 Gasserian gan- 
 glion . . . 
 
 Submaxillary 
 ganglion 
 
 Frontal, lachry- 
 mal and nasal 
 nn. 
 
 Orbital branch. 
 
 Infra-orbital n. 
 
 interior dental 
 
 n. 
 
 Naso-palatine n. 
 Palatine n. 
 
 Gustatory n. 
 
 DIAGRAM OF THE StJPEBIOB MAXILLABT NEBVE. 
 1. Spheno-palatine ganglion. 2. Otic ganglion. 
 
 it leaves the skull through the foramen rotundum, and passes hori- 
 zontally forwards across the spheno-maxillary fossa. It then passes 
 into the orbit through the spheno-maxillary fissure, 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. 217). 
 
 b. Two branches, which descend to the spheno-palatine ganglion 
 (Meckel's), situated in the spheno-maxillary fossa (p. 220). 
 
SUPERIOR MAXILLARY NERVE. 
 
 219 
 
 c. Posterior dental branches, two in number. They descend along 
 the back part of the superior maxillary bone. One lies between the 
 periosteum and the bone, and supplies the gums and mucous membrane ; 
 the other passes through a foramen in company with a small artery, and 
 running in an osseous canal supplies the molar teeth and the antrum ; it 
 gives off also a small branch which communicates with the anterior den- 
 tal nerve. 
 
 d. Anterior dental branch. This is given off just before the nerve 
 emerges from the infra-orbital foramen. It descends in a special canal 
 
 FIG. 44. 
 
 DEEP VIEW OF THE SPHEXOPALATINE GANGLION, AND ITS CONNECTION WITH OTHER 
 
 NEBVES. (After Hirschfeld.) 
 
 Superior marillary n. 
 
 Spheno-palatine ganglion, from the lower part 
 
 of which are seen proceeding the palatine 
 
 nerves. 
 
 Posterior superior dental brs. 
 Sixth n. receiving two filaments from the 
 
 carotid plexus of the sympathetic n. 
 The carotid br. of the Vidian. 
 The great petrosal br. of the Vidian. 
 Lesser petrosal nerve. 
 External deep petrosal n., uniting with lesser 
 
 petrosal n. 
 
 9. The internal deep petrosal nerve joining the 
 great petrosal nerve. 
 
 10. Filament to f enestra ovalis. 
 
 11. Filament to Eustachian tube. 
 
 12. Filament to fenestra rotunda, 
 
 13. Chorda tympaui. 
 
 14. Infra- orbital nerve. 
 
 15. Anterior dental n. 
 
 16. Junction of posterior and anterior dental 
 
 filaments. 
 
 17. Grlosso-pharyngeal n. giving off tympanic 
 
 branch. 
 
 in the anterior wall of the upper jaw, and divides into branches, which 
 distribute, filaments to the incisor, canine, and bicuspid teeth, the mu- 
 cous membrane of the antrum and the gums. 
 
220 SPHENO-PALATINE GANGLION. 
 
 e. The terminal branch, the infra-orbital, was dissected with the 
 face (p. 93). 
 
 At this stage of the dissection, make a vertical 
 
 DISSECTION. ... ,. . , . ,. .,,, ,. , 
 
 incision rather on one side of the middle line ot 
 
 the skull, to expose the cavity of the nose. Thus, by searching for 
 the spheno-palatine foramen, we are enabled to expose the spheno- 
 palatine ganglion. This may be readily made out by tracing the 
 terminal branch of the internal maxillary artery which comes 
 through the foramen into the nose. The student should next cut 
 away the thin plate of bone which forms the inner boundary of the 
 palatine canal. Then, by tracing upwards the branches contained 
 within the canal, he will find the ganglion. 
 
 SPHENO-PALA- This ganglion is called, after its discoverer, 
 
 TINE GANGLION. MeckeUs ganglion. It is about the fifth of an inch 
 in diameter. It is situated in the spheno-m axillary fossa, imme- 
 diately on the outer side of the spheno-palatine foramen. Like 
 other ganglia, it has three roots, a sensory, from the superior 
 maxillary ; a motor, from the great petrosal branch of the facial ; 
 and a sympathetic, from the carotid plexus. 
 
 Its branches pass upwards to the orbit ; downwards to the 
 palate ; inwards to the nose ; and backwards to the pharynx, as 
 follows : 
 
 a. Ascending branches. These are very small, and run through 
 the spheno-maxillary fissure to be distributed to the periosteum of the 
 orbit.* 
 
 b. Descending branches. 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 
 their accompanying arteries. They descend through the palatine canals, 
 and are three in number. The anterior palatine nerve, the largest, de- 
 scends through the posterior palatine canal to the roof of the mouth, and 
 then divides into branches, which run in grooves in the hard palate 
 nearly to the gums of the incisor teeth, where it communicates with the 
 
 * Anatomists describe several branches ascending from the ganglion, one to join 
 the sixth nerve, another to join the ophthalmic ganglion, and, lastly, some to join the 
 optic nerve through the ciliary branches, 
 
SPHENO-PALATINE GANGLION. 221 
 
 naso -palatine nerve. Within its canal it sends two nasal branches which 
 supply the membrane on the middle and lower spongy bones. The 
 smaller palatine descends in the same canal with the anterior, or in a 
 smaller one of its own, and supplies the mucous membrane of the soft 
 palate, the tonsil, and (according to Meckel) the levator palati muscle.* 
 The external palatine may be traced in a special canal down to the soft 
 palate, where it terminates in branches to the uvula, the palate, and tonsil. 
 
 c. Internal 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 in dilute nitric 
 acid ; afterwards, when well washed, these minute filaments may be 
 recognised beneath the mucous membrane covering the spongy bones. 
 The upper nasal branches pass inwards, and are distributed on the two 
 upper spongy bones, the upper and back part of the septum and the 
 posterior ethmoidal cells. The naso-palatine traverses the roof of the 
 nose, distributes branches to the back part of the septum narium, and 
 then proceeds obliquely forwards, along the septum, to the foramen in- 
 cisivum, through which it passes, and finally terminates in the palate 
 behind the incisor teeth communicating here with the anterior palatine 
 nerve. 
 
 d. Posterior branches. The pharyngeal nerve, very small, comes off 
 from the back of the ganglion, and, after passing through the pterygo- 
 palatine canal with its corresponding artery, supplies the mucous membrane 
 of the back of the pharynx and the Eustachian tube. The Vidian nerve 
 is the principal branch. It proceeds backwards from the posterior part 
 of the ganglion, through the Vidian canal. It then traverses the fibro- 
 cartilage of the foramen lacerum medium, and divides into two branches. 
 Of these two branches, one the carotid joins the sympathetic plexus 
 on the outer side of the internal carotid artery ; the other, the great 
 petrosal, enters the cranium, and runs beneath the Gasserian ganglion 
 and the dura mater in a small groove on the anterior surface of the petrous 
 bone : it then enters the hiatus Fallopii, and joins the facial nerve in the 
 aquseductus Fallopii. 
 
 * According to Longet (' Anat. et Physiol. du Systeme Nerveux,' Paris, 1842), 
 the posterior palatine nerve supplies the levator palati and the azygos uvulae with 
 motor power. In this view of the subject the nerve is considered to be the continua- 
 tion 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. 
 
222 OTIC GANGLION. 
 
 It would seem to be more in accordance with modern views to regard 
 the Vidian nerve, not as dividing to form the carotid and great superficial 
 petrosal branches, but rather as formed by the junction of these branches. 
 In this view, the Vidian runs, not from, but to the spheno-palatine 
 ganglion. 
 
 The otic ganglion is situated on the inner side 
 of the inferior maxillary division of the fifth nerve, 
 immediately below its exit through the foramen ovale (fig. 44). 
 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 small.* 
 
 This ganglion has branches of connection with other nerves : 
 namely, a sensory from the auriculo-temporal nerve ; a motor 
 from the branch of the inferior maxillary which goes to the 
 internal pterygoid muscle ; and a sympathetic from the plexus 
 around the arteria meningea media. It communicates also with 
 the facial and the glosso-pharyngeal nerves by the lesser petrosal 
 nerve. This branch passes backwards either through the foramen 
 ovale or the foramen spinosum, or through a small hole between 
 them, and runs beneath the dura mater in a minute groove on 
 the petrous bone, external to that for the great petrosal nerve. 
 Here it divides into two filaments, one of which joins the facial 
 nerve in the aquaeductus Fallopii, the other joins the tympanic 
 branch of the glosso-pharyngeal. These nerves are difficult to trace, 
 not only on account of their minuteness, but because they frequently 
 run in canals in the temporal bone. 
 
 The otic ganglion sends a branch forwards to the tensor palati, 
 and one backwards to the tensor tympani. 
 
 * J. Arnold. ' Diss. inaug. med.,' &c. Heidelbergse, 1826. 
 
DIAGRAM OF NERVE-COMMUNICATIONS. 
 
 223 
 
 FIG. 45. 
 
 N. to great petrosal . . 
 N. to lesser petrosal . . 
 
 N. to Eustachian tube. 
 N s. to carotid plexus . 
 
 Chorda tympani . . . 
 N. to stylo-hyoid . . 
 
 N. to digastricus . . . 
 Petrous ganglion . . . 
 
 Carotid plexus , . . 
 
 Branch to pharyngeal 
 plexus 
 
 Lingual branch . . . 
 Ganglion of the trunk . 
 
 Pharyngeal n. . 
 
 Superior laryngeal 
 
 Gangliform enlarge- 
 ment. 
 
 . tofenestra ovalis. 
 N. to fenestra ro- 
 tunda. 
 
 Tympanic n. 
 
 Auricular n. 
 
 Glosso-pharyngeal 
 
 n. 
 Jugular ganglion of 
 
 do. 
 
 Pneumogastric. 
 Ganglion of root. 
 
 Spinal accessory. 
 
 Hypoglossal. 
 
 Supr. cervical gan- 
 glion. 
 1st cervical n. 
 
 Br. to ganglion of 
 
 trunk. 
 2nd cervical n. 
 
 DIAGRAM OF THE COMMUNICATIONS OF THE FACIAL, GLOSSO-PHARYNGEAL, PNEUMO- 
 GASTEIC, SPINAL ACCESSORY, HTPOGLOSSAL, SYMPATHETIC, AND THE TWO tJPPEB 
 CBEVICAL NERVES. 
 
 1 . Great petrosal nerve. 
 
 2. Lesser do. 
 
 3. External do. 
 
 4. Nerve to Stapedius muscle. 
 
 5. Spheno-palatine ganglion. 
 
 6. Ocic ganglion. 
 
224 GANGLIA OP THE GLOSSO-PHARYNGEAL. 
 
 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 
 course. These are difficult to trace, and cannot be followed unless 
 the nerves have been previously hardened by spirit, and the bones 
 softened in acid. The next thing to be done is to remove the outer 
 wall of the jugular fossa. 
 
 GLOSSO-PHA- This nerve emerges from the cranium through a 
 
 BYNGEAL NEHVE. separate tube of dura mater, in front of that for 
 the other two nerves of the eighth pair. Looking at it from the 
 interior of the skull, we notice that it is situated in front and 
 rather to the inner side of the jugular fossa, where it lies in a 
 groove. 
 
 In its passage through the foramen, the nerve presents two 
 enlargements, termed the jugular and the petrous ganglia. 
 
 The jugular ganglion* is found upon the nerve immediately 
 after its entrance into the canal of the dura mater, and averages 
 about tK :^- of an inch in length and breadth. It is situated on 
 the outer side of the nerve, and does not implicate all its fibres. 
 According to our observation, this ganglion is not infrequently 
 absent. 
 
 The petrous ganglion^ is situated upon the glosso-pharyngeal 
 nerve, near the lower part of the jugular fossa. It is oval, about 
 ^ of an inch long, and involves all the filaments of the nerve. 
 It is connected by filaments with the pneumogastric and sym- 
 pathetic nerves, and it gives off the tympanic nerve. J The 
 branches which connect this ganglion with the pneumogastric are, 
 one to its auricular branch, and a second to the ganglion of the 
 root. It is also connected with the sympathetic by a small fila- 
 
 * Miiller, ' Medicin. Zeitung,' Berlin, 1833. No. 52. 
 f Andersch, 'Fragm. Descript. Nerv. Cardiac.' 1791. 
 | This nerve, though commonly called Jacobson's, was fully described by Andersch. 
 
PNEUMOGASTRIC NERVE AT THE BASE OP THE SKULL. 225 
 
 ment from the superior cervical ganglion. The tympanic nerve 
 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, where it terminates in six small filaments. Of these three 
 are branches of distribution, and three of connection with other 
 nerves. The branches of distribution are, one each to the fenestra 
 rotunda and the fenestra ovalis, and one to the Eustachian tube. 
 The connecting branches are two small filaments, which traverse 
 a bony canal to join the plexus on the outer side of the carotid 
 artery: the second ascends in front of the fenestra ovalis and 
 joins the great petrosal nerve in the hiatus Fallopii ; the third 
 takes nearly a similar course, and under the name of the lesser 
 petrosal nerve proceeds along the front surface of the pars petrosa 
 to the otic ganglion. Thus this tympanic branch is distributed 
 to the mucous membrane of the tympanum and the Eustachian 
 tube, and communicates with the spheno-palatine ganglion through 
 the great petrosal nerve, and with the otic ganglion through the 
 lesser petrosal. 
 
 PNEUMOGASTRIC This nerve leaves the cranium with the nervus 
 NEKVE. accessorius through a common 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 
 which are soon collected into a single trunk. In the jugular 
 foramen, the nerve presents a ganglionic enlargement, called the 
 ganglion of the root of the pneumogastric. This ganglion* 
 is about \ of an inch in length. It is connected by filaments 
 with the sympathetic through the superior cervical ganglion, with 
 the petrous ganglion of the glosso-pharyngeal, with the facial, and 
 with the spinal accessory by one or two branches. It gives off the 
 auricular branch^ which is distributed to the pinna of the ear. 
 This branch shortly after its origin is joined by a branch from 
 the glosso-pharyngeal, and enters a minute foramen in the jugular 
 fossa near the sty loid process. It then proceeds through a canal 
 in the bone, crosses the aqugeductus Fallopii, and passes to the 
 
 * Arnold, ' Der Kopftheil des Veget. Nerveu Systems.' Heidelberg, 1831. 
 f Arnold's nerve. 
 
 Q 
 
226 
 
 FACIAL NERVE IN THE TEMPORAL BONE. 
 
 outside of the head through the fissure between the mastoid 
 process and the meatus auditorius externus. It is distributed to 
 the skin of the auricle and communicates with the posterior 
 auricular branch of the facial nerve. 
 
 The facial nerve is contained within the meatus 
 auditorius internus, together with the auditory 
 nerve. At the bottom of the meatus the two 
 nerves are connected by one or more filaments. The facial nerve 
 then enters the aquseductus Fallopii. This is a tortuous canal 
 in the substance of the temporal bone, and terminates at the 
 
 Fra. 46. 
 
 FACIAL NERVE 
 
 IN THE 
 
 TEMPORAL BONE, 
 
 1 . The chorda tynipani. 
 
 2. The geniculate ganglion 
 
 of the facial nerve. 
 
 3. The great petrosal nerve. 
 
 4. The lesser petrosal nerve 
 
 lying oyer the tensor 
 tympani. 
 
 5. The external petrosal 
 nerve communicating 
 with the sympathetic 
 plexus on the arteria 
 meningea media (6). 
 
 7. The Gasserian ganglion. 
 
 THE GENICULATE GANGLION OF THE FACIAL NEEVE, AND ITS CONNECTIONS "WITH THE 
 
 OTHER N.ERVES. (From Bidder.) 
 
 stylo-mastoid foramen. The nerve proceeds from the meatus in- 
 ternus for a short distance outwards, where it presents a ganglionic 
 enlargement ; it then makes a sudden bend backwards along the 
 inner wall of the tympanum above the fenestra ovalis, and lastly, 
 curving downwards along the back of the tympanum, it leaves 
 the skull through the stylo-mastoid foramen. Its branches in 
 the temporal bone are : 
 
 a. Communicating filaments with the auditory nerve, in the meatus 
 auditorius internus. 
 
 b. The great petrosal nerve, which runs to the spheno-palatine gang- 
 lion. (Fig. 46. 3.) 
 
INTERNAL CAEOTID AT THE BASE OP THE SKULL. 227 
 
 c. The lesser petrosal nerve, which runs to the otic ganglion. 
 (Fig. 46. 4.) 
 
 d. The external petrosal, which connects the facial nerve with the 
 sympathetic plexus around the middle meningeal artery. (Fig. 46. 5.) 
 
 e. The nerve to the Stapedius muscle, which runs in the pyramid.' 
 (Fig. 45. 4.) 
 
 f. The chorda tympani, which joins the submaxillary ganglion. 
 
 The chorda tympani is given off from the facial nerve before 
 its exit from the stylo-mastoid foramen. It ascends a short 
 distance in a bony canal at the back of the tympanum, and enters 
 that cavity below the pyramid, close to the membrana tympani. 
 It runs forward, ensheathed in mucous membrane, through the 
 tympanum, between the handle of the malleus and the long process 
 of the incus, to the anterior part of that cavity. It then traverses 
 a special bony canal,* and emerges from the tympanum external 
 to the fissura Glaseri. It subsequently joins the lower border of 
 the gustatory nerve at an acute angle, and proceeds to the sub- 
 maxillary ganglion. It is said to supply the laxator tympani 
 muscle. f 
 
 COUESE OF IN- ^k e internal carotid takes a very tortuous 
 TEENAL CAEOTID course through the base of the skull before it 
 THBOUGH BASE OF reaches the brain. It makes no less than four 
 curves. It first curves forwards and inwards 
 through the carotid canal of the temporal bone; it makes a second 
 curve upwards through the cartilage in the foramen lacerum 
 medium ; it then makes a third curve forwards on the side of the 
 body of the sphenoid ; and, lastly, a fourth curve upwards on the 
 inner side of the anterior clinoid process, after which it enters the 
 cranial cavity, gives off the ophthalmic, and divides into the an- 
 terior cerebral, the middle cerebral, and the posterior communi- 
 cating arteries. 
 
 The internal carotid is accompanied in the carotid canal by 
 the cranial branch of the superior cervical ganglion of the sympa- 
 thetic, described p. 115. Its position on the inner wall of the 
 
 * Canal of Huguier. . 
 
 f This is probably not muscular, but ligamentous in structure. 
 Q 2 
 
228 CARTILAGES OF THE NOSE. 
 
 cavernous sinus, and the nervous plexuses upon it are described at 
 p. 16. 
 
 In the carotid canal the artery gives off a small branch to the mastoid 
 cells and the tympanum. 
 
 At this stage of the dissection we may conveniently trace the 
 anterior divisions of the two upper cervical nerves. 
 
 SUBOCCIPITAL The anterior division of the first cervical or 
 
 NERVE, suboccipital nerve descends in front of the trans- 
 
 verse process of the atlas to form a loop with the second cervical 
 nerve. It lies beneath the vertebral artery, on the inner side of 
 the rectus capitis lateralis to which it gives a branch ; and from 
 its loop of communication with the second nerve, it gives branches 
 to the recti antici muscles. This nerve is connected by filaments 
 with the superior cervical ganglion of the sympathetic, with the 
 hypoglossal and the pneumogastric nerves. 
 
 SECOND CERVI- The anterior division of this nerve emerges be- 
 CAL NEBVB. tween the arches of the atlas and axis, and passes 
 
 between the vertebral artery and the intertrans verse muscle, in 
 front of which it sub-divides into an ascending branch which joins 
 the first cervical nerve, and a descending, which joins the third 
 cervical nerve. 
 
 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, 4. The 
 distribution of the olfactory nerves. 
 
 CARTILAGES OF The framework of the external nose is formed, 
 
 THE NOSE. on each side, by two lateral cartilages; and by 
 
 one in the centre, which completes the septum between the nasal 
 fossae. 
 
 The lateral cartilages are termed, respectively, upper and 
 lower. The upper, triangular in shape, is connected, superiorly, to 
 
CAETILAGES OF THE NOSE. 229 
 
 the margin of the nasal and superior maxillary bones ; anteriorly to 
 the cartilage of the septum, and, inferiorly, to the lower cartilage 
 by means of a tough fibrous membrane. The loiver is elongated, 
 and curved upon itself in such a way as to form not only half the 
 apex but the lateral boundary of the external opening of the nostrils. 
 Superiorly, it is connected by fibrous membrane to the upper 
 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 -sesamoidece. By their 
 elasticity these several cartilages 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. 82). 
 
 INTERIOR OF . A vertical section should be made through the 
 THE NOSE. right nasal cavity, a little on the same side of the 
 
 middle 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 ; from this point the depth 
 gradually lessens towards the anterior and the posterior openings 
 of the nose. Laterally, each fossa is very narrow in consequence 
 of the projection of the spongy bones towards the septum : this 
 
230 MEATUSES OP THE NOSE. 
 
 narrowness in the transverse direction explains the rapidity with 
 which swelling of the lining membrane from a simple cold 
 obstructs the passage of air. 
 
 BOUNDARIES The nasal fossae are bounded by the following 
 
 OF NASAL FOSSJE. bones : superiorly, 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 perpendicular plate of the ethmoid, the 
 ridge formed by the two nasal bones, the vomer, the septal car- 
 tilage, 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 superior maxillary, the lachrymal, 
 the ethmoid, the palate, the inferior turbinated bone, and the 
 internal pterygoid plate of the sphenoid. 
 
 MEATUSES OF The outer wall of each nasal cavity is divided 
 
 THE NOSK. by the turbinated bones into three compartments 
 
 meatuses of unequal size ; and in these are orifices leading to 
 air-cells sinuses in the sphenoid, ethmoid, frontal, and superior 
 maxillary bones. 'Each of 'these compartments should be separately 
 examined. 
 
 a. 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 it. The 
 spheno-palatine foramen is covered by the mucous membrane. 
 
 6. The middle meatus is larger than the superior. At its an- 
 terior part a long narrow passage (infundibulum), nearly hidden 
 by a fold of membrane, leads upwards to the frontal and the 
 anterior ethmoidal cells. About the middle a small opening leads 
 into the antrum of the superior maxilla : this opening in the dry 
 bone is. large and irregular, 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 away easily into the nose. 
 
MEATUSES OF THE NOSE. 231 
 
 But this is not the case with the maxillary cells, to empty which 
 the head must be inclined on one side. To see all these openings 
 the respective turbinated bones must be raised. * 
 
 c. The inferior meatus extends nearly along the whole length of 
 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 can now be con- 
 veniently examined. 
 
 LACHBTMALSAC The lachrymal sac and nasal duct constitute 
 AND NASAL DUCT, the passage through which the tears are conveyed 
 from the lachrymal ducts into the nose (p. 81). The lachrymal 
 sac occupies the groove on the nasal side of the orbit. The upper 
 end is round and closed ; the lower gradually contracts into the 
 nasal duct, and opens into the inferior meatus. The sac is com- 
 posed of a strong fibrous and elastic tissue, 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 proceeding 
 from it. 
 
 The nasal duct is from half to three-quarters of an inch in 
 length, and is directed downwards, backwards, and a little out- 
 wards. Its termination is guarded by a valvular fold of mucous 
 membrane ; consequently, 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 epithelium, and the canaliculi with the squamous variety. 
 
 Behind the inferior turbinated bone is the opening of the 
 Eustachian tube (p. 186). Into this, as well as into the nasal duct, 
 we ought to practise 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 OB This membrane lines the cavities of the nose 
 
 SCHNEIDERIAN and the air-cells communicating with it, and 
 
 MEMBRANE.* adheres very firmly to the periosteum. Its con- 
 
 * Schneider, ' De catarrhis.' Wittenberg, 1660. 
 
232 MUCOUS MEMBRANE OF THE NOSE. 
 
 tinuity may be traced into the pharynx, into the various sinuses, 
 into the orbits through the iiasal ducts, and into the tympana and 
 mastoid cells through the Eustachian tubes. At the lower border 
 of the turbinated bones it is disposed in thick and loose folds. 
 The membrane varies in thickness and vascularity in different 
 parts of the nasal cavities. Upon the lower half of the septum 
 and the inferior turbinated bones, it is much thicker than elsewhere, 
 owing to a fine plexus of arteries and veins in the submucous 
 tissue. In the sinuses the mucous membrane is thinner, less 
 vascular, and closely adherent to the periosteum. 
 
 The great vascularity of the mucous membrane raises the 
 temperature of the inspired air, and pours out a copious secretion 
 which prevents the membrane from becoming too dry. 
 
 The mucous membrane of the nasal cavities is not lined 
 throughout by the same kind of epithelium. Near the nostrils 
 the mucous membrane is furnished with papillae, with a squamous 
 epithelium like the skin, and a few small hairs (vibrissce). In 
 the lower part of the nose namely, along the respiratory tract and 
 in the sinuses the epithelium is columnar and ciliated ; but in 
 the true olfactory region that is, upon the superior and middle 
 turbinated bones and the upper half of the septum the epithe- 
 lium is columnar, but not ciliated. In this region the mucous 
 membrane is extremely vascular, thick, and studded with simple 
 mucous glands. The columnar epithelial cells taper off at their 
 deep ends into fine processes. Lying between these processes are 
 fusiform cells, with central well-defined nuclei, to which the name 
 of olfactory cells has been given ; and it is probable that the 
 attenuated processes which pass inwards from these cells are in 
 direct connection with the terminal fibrils of the olfactory 
 nerves. 
 
 The arteries of the nasal cavities are derived from the an- 
 terior and posterior ethmoidal branches of the opththalmic, and 
 from the nasal branch of the internal maxillary, which enters 
 the nose through the spheno-palatine foramen. The external nose 
 is supplied by the nasal branch of the ophthalmic (p. 215), the 
 arteria lateralis nasi, the angular, and the artery of the septum. 
 
MUCOUS MEMBRANE OP THE NOSE. 233 
 
 The veins of the nose correspond with the arteries. They 
 communicate with the veins within the cranium through the 
 foramina in the cribriform plate of the ethmoid bone ; also 
 through the ophthalmic vein and the cavernous sinus. These com- 
 munications explain the relief frequently afforded by haemorrhage 
 from the nose in cases of cerebral congestion. 
 
 The mucous membrane of the nose is supplied with sensory 
 nerves by the fifth pair. Thus, its roof is supplied with filaments 
 from the external branch of the nasal nerve, and from the Vidian ; 
 its outer wall, by filaments from the superior nasal branches of 
 the spheno-palatine ganglion, from the nasal, from the inner branch 
 of the anterior dental, and from the inferior nasal branches of the 
 large palatine nerve ; its septum, by the septal branch of the 
 nasal nerve, by the nasal branches of the spheno-palatine ganglion, 
 by the naso-palatine, and by the Vidian : its floor, by the naso- 
 palatine, and the inferior nasal branches of the large palatine nerve. 
 OLFACTORY The olfactory nerves, proceeding from each 
 
 NERVES. olfactory bulb, in number about twenty on each 
 
 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 arranged into an inner, 
 a middle, and an outer set. The inner, which are the largest, 
 traverse the grooves in the upper third of the septum. The 
 middle ramify on the roof of the nose. The outer pass through 
 grooves in the upper and middle turbinated bones and the os 
 planum of the ethmoid. 
 
 The nerves descend between the mucous membrane and the 
 periosteum, and break up into filaments which communicate freely 
 with one another, and form minute plexuses with small elongated 
 intervals. Microscopically, the filaments differ from the other 
 cerebral nerves, in containing no white substance of Schwann, and 
 in being pale, finely granular, and nucleated. 
 
234 MUSCLES OP THE BACK. 
 
 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, which extend from the spine to the ribs. 
 
 SERRATUS Pos- This muscle is situated beneath the rhomboidei. 
 
 TICUS SUPERIOR. it i s a thin flat muscle and arises from the 
 lower part of the ligamentum nuchog,* from the spines of the last 
 cervical, and two or three upper dorsal vertebrae, by a sheet-like 
 aponeurosis which makes up nearly half the muscle : the fibres run 
 obliquely downwards and outwards, and are inserted by four fleshy 
 slips into the second, third, fourth, and fifth ribs beyond their 
 angles. Its action is to raise these ribs, and therefore to assist in 
 inspiration. 
 
 SERRATUS Pos- This muscle is situated beneath the latissimus 
 
 TICUS INFERIOR. dorsi. It arises from the spines of the two last 
 dorsal and two upper lumbar vertebrae by means of the lumbar 
 aponeurosis. It ascends obliquely outwards, and is inserted by 
 four fleshy slips into the four lower ribs, external to their angles. 
 Its action is to pull down these ribs, and therefore to assist in 
 expiration The posterior serrati muscles are supplied by the 
 posterior divisions of the spinal nerves. 
 
 VERTEBRAL The thin aponeurosis which separates the 
 
 APONEUROSIS. muscles of the upper extremity from those of the 
 
 back is called vertebral aponeurosis. Superiorly, it is continued 
 beneath the serratus posticus superior ; inferiorly, it binds down 
 the muscles contained in the vertebral groove, by stretching 
 
 * The ligamentum nuchse is a rudiment of the great elastic ligament of quadru- 
 peds (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 ; 
 otherwise it would interfere with the free rotation of the head. 
 
MUSCLES OF THE BACK. 235 
 
 across from the spinous processes to the angles of the ribs : it is 
 also connected below with the aponeurosis of the latissimus dorsi 
 and the serratus inferior. 
 
 This aponeurosis consists of three layers, of 
 LUMBAR FASCIA. , . , . , . , , , 
 
 which only the posterior layer can now be seen ; 
 
 the other two being demonstrated in the dissection of the abdominal 
 muscles. The posterior or superficial layer is attached to the crest 
 of the ilium, to the spinous processes of all the lower dorsal, 
 lumbar, and sacral vertebrae ; it forms a sheath for the erector 
 spinse, and serves for the attachment of the latissimus dorsi, and 
 the serratus posticus inferior. 
 
 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 dorsal and the last cervical vertebra, and 
 
 from the lower half of the ligamentum nuchse. 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 into the outer part of the superior curved line 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 upper three 
 cervical vertebrae. The splenius is supplied by the posterior 
 divisions of the spinal nerves. 
 
 The action of the splenius, taken as a whole, is to draw the 
 head and the upper cervical vertebras towards its own side : so far, 
 it eo -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 ap- 
 pearance of the distortion is alike in either case. 
 
 The splenius and serratus posticus inferior are 
 to be detached from their origins. After reflect- 
 
236 MUSCLES OF THE BACK. 
 
 ing the lumbar fascia from its internal attachment, the erector 
 spinse is exposed. 
 
 EEKCTOB The mass of muscle which occupies the vertebral 
 
 SPIN*:. groove on either side of the spine, is, collectively, 
 
 called erector spince, 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 lower part and back of the sacrum, and 
 the spines of the lumbar vertebrae. 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 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. 
 
 SACRO- Tracing the sacro-lumbalis upwards, we find 
 
 LUMBALIS. that it terminates in a series of tendons which are 
 
 {inserted into the angles of the six lower ribs. 
 
 MUSCULUS By turning outwards the sacro-lumbalis, we 
 
 ACCESSOBIUS. observe that it is continued upwards under the 
 
 name of musculus accesswius ad sacro-lumbalem. This arises 
 by a series of tendons from the angles of the seven or eight lower 
 ribs, internal to the preceding, and is inserted into the angles of 
 the five or six upper ribs. 
 
 CEKYICALIS This is the cervical continuation of the mus- 
 
 ASCENDENS. culus accessorius. It arises by tendinous slips 
 
 from the four or five upper ribs, and is inserted into the transverse 
 processes of the fourth, fifth and sixth cervical vertebrae. 
 
 LONGISSIMUS The longissimus dorsi (the inner portion of the 
 
 Doasi. erector spinae) terminates in tendons which are 
 
 inserted, internally, into the tubercles * at the root of the transverse 
 * Called ' anapophyses' by Professor Owen. 
 
MUSCLES OP THE BACK. 237 
 
 processes of the lumbar vertebrae, also into the transverse processes 
 of all the dorsal vertebrae, and, externally, into the greater number 
 of the ribs (varying from eight to eleven) between their tubercles 
 and angles, and, lower down, into the lumbar fascia, and into the 
 transverse processes of -the lumbar vertebrae. 
 
 TRANSVERSALS This is the cervical continuation of the longissi- 
 COLIJ. mus 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 vertebras 
 except the last. 
 
 TRACHELO- This muscle, situated on the inner side of the 
 
 MASTOID. -preceding, is the internal continuation of the 
 
 longissimus dorsi to the cranium. It arises from the transverse 
 processes of the three or four upper dorsal, and the articular pro- 
 cesses 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.* 
 
 * 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 diapophy&is 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 
 lougissimus dorsi. 
 
 ' 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 
 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 pleur- 
 apophysial 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 
 verttbra. 
 
238 MUSCLES OP THE BACK. 
 
 This is a long narrow muscle, situated close to 
 SPINALIS DOESI. , . 
 
 the spines of the dorsal vertebrae, and apparently 
 
 a part of the longissimus dorsi ; it is by some considered the inner- 
 most column of the erector spinae. 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 vertebra?. 
 
 The muscles of the spine hitherto examined are all longitudinal 
 in their direction. We now come to a series which run obliquely 
 from the transverse to the spinous processes of the vertebrae. And 
 first of the complexes. 
 
 This powerful muscle arises- from the transverse 
 
 COMPLEXUS. , 1 1 J AT. 
 
 processes ot the six or seven upper dorsal and the 
 last cervical vertebrae, also from the articular processes of four or 
 five 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 a tendinous intersection. The muscle is 
 perforated by the posterior branches of the second (the great occi- 
 pital), third, and fourth cervical nerves. It is chiefly supplied by 
 the great occipital nerve. Its action is to maintain the head 
 erect. 
 
 Cut transversely through the middle of the complexus, and 
 reflect it to see the arteria cervicalis profunda (p. 69), and the 
 posterior branches of the cervical nerves. 
 
 TRANSVEESO This is the mass of muscle which lies in the 
 
 SPINALIS. vertebral groove after the reflection of the com- 
 
 plexus and the erector spinae. It consists of a series of fibres 
 which extend from the transverse and articular processes to the 
 
 ' 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 Skelc ton,' by H. Coote, p. 7& 
 
MUSCLES OF THE BACK. 239 
 
 spinous processes of the dorsal and cervical vertebrae, and is for 
 convenience divided into the semispinalis dor si and semispinalis 
 colli. 
 
 a. The semispinalis dorsi arises from the transverse processes 
 of the dorsal vertebrge, from the sixth to the tenth, and is inserted 
 into the spines of the four upper dorsal and the two or three lower 
 cervical vertebrae. 
 
 6. The semispinalis colli lies beneath the complexus and arises 
 from the transverse processes of the five or six upper dorsal ver- 
 tebrge, and the articular processes of the four lower cervical, and 
 is inserted into the spines of the axis and the three or four 
 succeeding vertebrae, that into the axis being the most fleshy 
 fasciculus. 
 
 Now reflect part of the semispinalis dorsi in order to expose 
 the multifidus spince. This may be considered a part of the 
 preceding 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 vertebras 
 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 laminae 
 of all the vertebras excepting the atlas. It should be observed 
 that their fibres are not of uniform length j some extend only from 
 vertebra to vertebra, while others extend between one, two, or 
 even three vertebrae. 
 
 Beneath the multifidus spinaa, in the dorsal region of the spine 
 only r are eleven flat muscles, called rotatores spinee. They arise 
 from the upper part of the transverse processes, and are inserted 
 into the lower border of the laminae of the vertebra above. These 
 muscles form but a part of the multifidus spinas. 
 
 The action of the preceding muscles is, not only to assist in 
 maintaining the trunk erect, but to incline and rotate the spine 
 to one or the other side. They are all supplied by the posterior 
 branches of the spinal nerves. 
 
240 MUSCLES OP THE BACK. 
 
 LEVATORES These small muscles arise from the apices of the 
 
 COSTAKUM. transverse processes of the seventh cervical and 
 
 the eleven upper dorsal vertebrae, and are inserted into the rib 
 below. The direction of their fibres corresponds with that of the 
 outer layer of the intercostal muscles. They are muscles of in- 
 spiration. 
 
 These muscles extend between the spines of 
 INTEESPINALES. . . , , _,, , . 
 
 contiguous vertebrae. They are arranged in pairs, 
 
 and only exist in those parts of the vertebral column which are the 
 most movable. 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. They are also 
 found more or less distinctly between the spines of the lumbar 
 vertebrae. 
 
 INTERTRANS- These muscles extend between the transverse 
 
 VERSALES. processes 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 
 lumbar region they are four in number, and are arranged also in 
 pairs. 
 
 We have next to examine the muscles concerned in the move- 
 ments of the head upon the first and second cervical vertebrae. 
 (Fig. 47.) 
 
 KECTUS CAPITIS This is a largely developed interspinal muscle. 
 POSTICUS MAJOK. It arises by a small tendon from the well-marked 
 spine of the second cervical vertebra, and, expanding considerably, 
 is inserted below the superior curved ridge of the occipital bone. 
 These recti muscles, as they ascend, one on each side, to their in- 
 sertions, diverge and leave an interval between them in which are 
 found the recti capitis postici minores. 
 
 KECTUS CAPITIS This is also an interspinal muscle, but smaller 
 POSTICUS MINOR. than the preceding. Arising from the posterior 
 tubercle of the first vertebra, it expands as it ascends, and is in- 
 serted into the occipital bone between the inferior curved ridge 
 and the foramen magnum. The action of the two preceding 
 
SUB-OCCIPITAL TRIANGLE. 
 
 241 
 
 muscles is to raise the head. They are supplied with nerves from 
 the posterior branch of the sub-occipital. 
 
 OBLIQUUS This arises from the spine of the second cer- 
 
 INFERIOR. vical vertebra, and is inserted into 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 to the 
 same side. It is supplied with a nerve by the great occipital 
 
 FIG. 47. 
 
 DRAWING FROM NATURE OF THE SUBOCCIPITAL TRIANGLE. 
 
 1 and 7. Complexus. 2. Kectus cap. posticus minor. 3. Rectus cap. posticns major. 4. Obliquus 
 inferior. 5. Sterno-mastotd. 6. Semispinalis colli. 8. Obliquus superior. 10. Splenins. 
 11. Trachelo-mastoid. 12. Great occipital nerve. 13. Occipital artery giving off its descending 
 branch the princeps cervicis. 14. Suboccipital nerve. 15. Third cervical nerve (posterior 
 branch). 
 
 (posterior division of the second cervical) which curves up under 
 its lower border. 
 
 OBLIQUUS This muscle arises from the transverse process 
 
 SUPERIOR. o f the atlas, and, ascending obliquely inwards, is 
 
 inserted in the interval between the curved ridges of the occipital 
 bone. Its action is to draw the occiput towards the spine. 
 
 
 
242 NERVES OP THE BACK. 
 
 STOOCCIPITAL Observe that the obliqui (superior and inferior) 
 
 TRIANGLE. an( j the rectus capitis posticus major form what 
 
 is called the suboccipital triangle. The outer side is formed 
 by the obliquus superior; the inner, by the rectus capitis pos- 
 ticus major ; the lower, by the obliquus inferior. Within this 
 triangle may be seen the arch of the atlas, and the vertebral artery 
 lying in a groove on its upper surface. Between the artery and 
 the bone appears the posterior division of the suboccipital nerve, 
 which here sends branches to the recti postici, the obliqui, and the 
 complexus : that is to say, it supplies the muscles which form the 
 triangle, and the complexus that covers it. 
 
 EECTUS CAPITIS This small muscle extends between the trans- 
 LATEKALTS. verse process of the first vertebra and the eminen- 
 
 tia jugularis of the occiput ; but, since this eminence is the trans- 
 verse process of the occipital vertebra, the muscle should be 
 considered as an intertransverse one. Its nerve comes from the 
 anterior division of the sub-occipital. 
 
 NERVES OF THE The posterior branches of the spinal nerves 
 BACK. supply 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 peculi- 
 arities deserving of notice in particular situations, we must examine 
 each region separately. 
 
 CERVICAL The posterior division of the first cervical nerve 
 
 EEGION. (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. It also sends downwards a loop to communicate with 
 the second cervical nerve. 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 
 
NEEVES OP THE BACK. 243 
 
 oblique muscle, passes through the complexus, and runs with the 
 occipital artery to the back of the scalp. 
 
 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 
 spinse viz., the trachelo-mastoid, 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 skin ; those of- the 
 sixth, seventh, and eighth lie between the semispinalis and the 
 multifidus spinse, to which they are distributed. 
 
 DORSAL The posterior divisions of the spinal nerves in 
 
 REGION. this region come out between the transverse pro- 
 
 cesses 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 down- 
 wards. 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. 
 
 LUMBAR The general arrangement of the nerves in this 
 
 EEGION. region resembles that of the dorsal. Their exter- 
 
 nal branches, after supplying the erector spinse, 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 
 SACKAL REGION. . 
 
 this region are small. With the exception of the 
 
 * 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. 
 
 K 2 
 
244 PE^EVEETEBEAL MUSCLES. 
 
 last, they come out of the spinal canal through the foramina in 
 the back of the sacrum. The upper two or three divide into 
 external and internal branches. The internal terminate in the 
 multifidus spinae ; 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.* 
 
 ARTERIES OF The arteries which supply the back are: 1. 
 
 THE BACK. Small branches from the occipital; 2. Small 
 
 branches from the vertebral ; 3. The deep cervical ; 4. The pos- 
 terior branches of the intercostal and lumbar arteries. 
 
 The occipital artery furnishes several small branches to the 
 muscles at tbe back of the neck ; one, larger than the rest, the 
 arteria princeps cerv ids, descends beneath 'the complexus, and 
 generally inosculates with the. deep- cervical -artery, and with small 
 branches from the vertebral. 
 
 The vertebral artery runs along the groove in the arch of the 
 atlas, and, before perforating the posterior occipito-atlantoid liga- 
 ment to enter the skull, distributes small branches to the adjacent 
 muscles. 
 
 The deep cervical artery is the posterior branch of the first 
 intercostal artery (from the subclavian). 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, and anastomoses with the princeps cervicis. 
 
 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 (intraspinal), and small branches to the vertebra. 
 
 The veins correspond to the arteries. 
 
 PR;E-VERTEBHAL We have, lastly, to examine three muscles 
 MUSCLES. situated in front of the spine : namely, the longus 
 
 colli, the rectus capitis anticus major, and the rectus capitis 
 
 * The branching of the posterior divisions of the several spinal nerves has been 
 accurately described by Ellis, 'Med. Gazette,' Feb. 10, 1813. 
 
PE^EVEETEBBAL MUSCLES. 245 
 
 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. 
 
 This muscle 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 sets of fibres, of which one extends longitudinally from 
 the body of one vertebra to that of another ; the two others extend 
 obliquely between the transverse processes and the bodies of the 
 vertebrae. 
 
 The longitudinal portion of the muscle arises from the bodies 
 of the two or three upper dorsal and ^ the three lower cervical 
 vertebras, and is inserted into the bodies of the second*, third and 
 fourth cervical vertebras. 
 
 The superior oblique portion, arising from the anterior 
 tubercles of the transverse processes of the third, fourth, and 
 fifth cervical vertebra?, ascends inwards, and is inserted into 
 the front part or body of the first cervical vertebra. The in- 
 ferior oblique portion proceeds from the bodies of the three 
 upper dorsal vertebras, and is inserted into the transverse pro- 
 cesses 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 cervical and brachial 
 plexuses. 
 
 EECTUS CAPITIS This muscle arises from the anterior tubercles 
 ANTICUS MAJOH. o f the transverse processes of the third, fourth, 
 fifth, and sixth cervical vertebras, and is inserted into the 
 basilar process of the occipital bone, in front of the foramen 
 magnum. 
 
 EECTUS CAPITIS This muscle arises* from the root of the trans- 
 ANTICUS MINOB. verse process 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 anterior division of the sub- 
 occipital. 
 
246 LIGAMENTS OP THE SPINE. 
 
 LIGAMENTS OF THE SPINE. 
 
 The vertebrae are connected by their intervertebral fibro-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 synovia! 
 membranes. 
 
 ANTERIOR COM- This is a strong band of longitudinal fibres 
 MON LIGAMENT. which extends along the front of the bodies of the 
 vertebrae from the axis to the 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 
 preceed 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. 
 
 POSTEEIOR COM- This extends longitudinally, in a similar manner 
 MON LIGAMENT. to the anterior common ligament, along the 
 posterior surface of the bodies of the vertebrae, from the axis to 
 the sacrum, and sends up a prolongation to the anterior border 
 of the foramen magnum continuous with the apparatus liga- 
 mentosus. 
 
 INTERSPINOTTS These bands of ligamentous fibres fill up the 
 
 LIGAMENTS. intervals between the spines of the dorsal and 
 
 lumbar vertebrae. 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. 
 
 LIGAMENTS These are called, on account of their colour, 
 
 BETWEEN THE Ugamenta sub/lava. To obtain a good view 
 
 ARCHES OF THE o f them, the arches of the vertebrae should be 
 
 removed with a saw. They pass between the 
 
LIGAMENTS OP THE SPINE. 247 
 
 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, the 
 fibres being arranged vertically, 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 Ugamentum nuchae in animals. 
 
 INTKEVERTE- This substance, placed between the bodies of 
 
 BRAL FIBEO- the vertebrae, is by far the strongest bond of con- 
 
 nection between them, and fulfils most important 
 purposes in 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 it. It is firm and 
 resisting 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 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 
 an elastic cushion 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 v-ertebrae, 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 
 
248 LIGAMENTS OF THE SPINE. 
 
 fact that a man becomes shorter after standing for some hours ; and that 
 he regains his usual height after rest. The difference between the morn- 
 ing 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 late- 
 ral curvature depends more frequently upon some alteration in the struc- 
 ture 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 inver- 
 tebral substances, these being, on the concave side of the curve, almost 
 absorbed, and, on the convex side, preternaturally developed. As might 
 be expected in these cases, the muscles on the convex side become 
 lengthened, and degenerate in structure.* 
 
 LIGIAMENTUM This ligament is a thin fibrous septum inter- 
 
 NUCHJE. mingled with elastic tissue, which extends from 
 
 the spinous processes of the six lower cervical vertebrae to the 
 external occipital protuberance. It forms an intermuscular septum 
 down the back of the neck, and may be regarded as the continua- 
 tion upwards of the supra-spinous ligament. 
 
 CAPSULAB Each joint between the articular processes has 
 
 LIGAMENTS. a capsular ligament and a synovial membrane. 
 
 The surfaces of the bones are crusted with cartilage. 
 
 INTEBTBANS- These are thin bands of fibres which pass be- 
 
 VERSE LIGAMENTS, tween the transverse processes of the vertebrae. 
 They are rudimentary in the cervical region, and are sometimes 
 absent. 
 
 MOVEMENTS OF Though but little movement is permitted be- 
 THE SPINE. tween any two vertebrae (the atlas and axis ex- 
 
 cepted), 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 intervertebral cartilages and the ligamenta subflava, it 
 returns spontaneously to its natural curve of rest like an elastic 
 bow. Its mobility is greatest in the cervical region, on account of 
 
 * On this subject see ' Hildebrandt's Anatomic,' B. ii. s. 155. 
 
LIGAMENTS OF THE SPINE. 249 
 
 the thickness of the fibro-cartilages, the small size of the vertebrae, 
 the oblique direction of their articulations, and, above all, trhe 
 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. 
 
 LIGAMENTS BB- ^ ne cc iput is connected to the atlas by an 
 TWEBN THE Occi- anterior occipito-atlantoid ligament which passes 
 PITAL BONE AND from the foramen magnum to the front arch of 
 
 IE TLAS. ^ e a i ag< rpj^ thickest part of this is in the 
 
 middle. A posterior occipito-atlantoid ligament extends in a 
 similar manner from the posterior border of the foramen magnum 
 to the posterior arch of the atlas. It is thin and, superiorly, be- 
 comes blended with the dura mater, and is pierced by the vertebral 
 artery and the suboccipital nerve. Between the condyles of the 
 occipital bone and the atlas, there is on each side a capsular 
 ligament. 
 
 The movements which take place between the occipital bone 
 and the atlas are flexion and extension, as in nodding forwards 
 and backwards ; and lateral movement, as in inclining the head 
 sideways. 
 
 LIGAMENTS These are the most important ; and to see them, 
 
 BETWEEN THE the spinal canal must be exposed by removing the 
 
 OCCIPITAL BONE arches of the upper cervical vertebrae, and the 
 posterior common ligament, which is here very 
 thick and strong. It descends from the basilar process of the 
 occipital bone over the odontoid and transverse ligaments, and is 
 called the occipito-axoid ligament or the apparatus liga- 
 mentosus colli. 
 
 ODONTOID ou The odontoid or check ligaments (fig. 48) are 
 
 CHECK LIGAMENTS, two very strong ligaments which proceed from 
 the sides of the odontoid process to the tubercles on the inner 
 sides of the condyles of the occiput. Their use is to limit the 
 
250 
 
 LIGAMENTS OP THE SPINE. 
 
 rotation of the head. A third or middle odontoid ligament passes 
 from the apex of the odontoid process to the margin of the 
 foramen magnum. It is sometimes called the ligamentum sus- 
 pensorium. 
 
 The odontoid process of the axis forms a pivot 
 upon which the head and atlas rotate. The most 
 important ligament is the transverse (fig. 48). It 
 passes behind the odontoid process, and is attached 
 to the tubercles on the inner sides of the articular processes of the 
 
 - FIG. 48. 
 
 ARTICULATION 
 BETWEEN THE 
 ATLAS AND THE 
 Axis. 
 
 POST? COMMON LICT 
 
 DIAGRAM OF THE ODONTOID AND TRANSVERSE' LIGAMENTS. 
 
 atlas. From the cerftre of this ligament a few fibres pass upwards, 
 to be attached to the basilar process, and some downwards to the 
 body of the axis, 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 odon- 
 toid process is covered with cartilage in front and behind, and is 
 provided with two synovial membranes. 
 
 The anterior arch of the atlas is connected to the body of the 
 axis by the anterior atlanto-axoid ligament ; posteriorly, the two 
 arches are connected by the posterior atlanto-axoid ligament. 
 
LIGAMENTS OF THE RIBS. 251 
 
 ARTICULATION- All the ribs, with the exception of the first and 
 
 OF THE EIBS. the two last, are articulated with the bodies of two 
 
 vertebrae, and with -the transverse processes (fig. 49). 
 
 The headof each rib presents two articular surfaces, correspond- 
 ing- to the bodies of two vertebrae. 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 vertebras, .and with the intervening fibro-cartilage : 
 this, on account of the divergence of . its fibres, is called the stel- 
 late ligament (fig. 50). 2. ., An intern-articular, ..which proceeds 
 from the head of the rib to the intervertebral cartilage. 
 
 FIG. 49. 
 
 DIAGRAM SHOWING THE LIGAMENTS CONNECTING THE RIB WITH THE VERTEBRA. 
 
 1. The anterior costo-central ligament. 3. The posterior costo-transverse ligament. 
 
 2. The interosseous, or middle costo-transverse . 4. The synovial membrane between the rib and 
 
 ligament. the body of the vertebra. 
 
 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 
 summit of the tubercle of the rib. 2. The middle costo-trans- 
 verse connects the neck of the rib to the front surface of the 
 transverse process. 3. The superior costo-transverse ascends from 
 the neck of the rib to the lower border of the transverse process 
 above it (fig. 50). 
 
252 ARTICULATION OP THE LOWER JAW. 
 
 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 
 CONNECTION 
 
 BETWEEN THE in ^o slight concavities on the side of the sternum, 
 
 CARTILAGES OF aiad are secured by anterior^ posterior, upper and 
 THE RIBS AND THE i ower ligaments. There is a synovial membrane 
 between the cartilage of each rib and the sternum, 
 except that of the first, and usually at each articulation the synovial 
 membrane is separated into two by an inter-articular ligament. 
 
 m. ^fS^&rn ^BW"* n imfff 
 I. 1. 1. Superior costo- %*=* 5 *^ W_^ w- t ', / 2. 2. 2. Anterior costo-cen- 
 
 transverse ligaments. ^^-X'lvSr M BH "^JOA * ra ^ or stellate ligaments. 
 
 COSTO-VERTEBEAT, LIGAMENTS. 
 
 The cosiai cartilages from the sixth to the tenth are connected 
 by ligamentous fibres. 
 
 ARTICULATION ^ ne con dyle of the lower jaw articulates with 
 
 or THE LOWER the glenoid cavity of the temporal bone. The 
 JAW - joint is provided with an inter-articular fibro- 
 
 cartilage, with external and internal lateral ligaments, and two 
 synovial membranes (fig. 51). 
 
 The external lateral ligament extends from the zygoma and its 
 tubercle ; its fibres pass 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 
 
ARTICULATION OP THE LOWER JAW. 
 
 253 
 
 the joint : the articulation of one side performs the office of inter- 
 nal lateral ligament to the other. 
 
 The inter-articular fibro-vartilage is a thin plate 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 muscle are in- 
 serted into it. 
 
 FIG. -51. 
 
 Section through the gtenoid cavity 
 Inter- articular fibro- 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 STNOVIAL 
 MEMBRANES. 
 
 There are two synovial membranes, an upper and a lower, for 
 the joint. The larger and looser of the two is situated between 
 the glenoid cavity and the fibre-cartilage. The lower is interposed 
 between the fibro- cartilage and the condyle of the jaw. They 
 sometimes communicate through a small aperture in the centre of 
 the fibro-cartilage. 
 
 The form of the articulation of the lower jaw admits of move- 
 ment, upwards and downwards, forwards, backwards, and from side 
 
254 ABTICULATION OP THE LOWER JAW. 
 
 to side. A combination of these movements takes place in masti- 
 cation : during this act the condyles of the jaw describe an oblique 
 rotatory movement in the glenoid cavity. The purposes served by 
 the nbro-cartilage in this joint are : first, it follows the condyle, 
 and interposes a convenient socket for all its movements : second, 
 being elastic, it breaks shocks ; for shocks here would be almost 
 fatal, considering what a thin plate of bone the glenoid cavity is, 
 and that just above it is the brain. 
 
255 
 
 DISSECTION OF THE UPPER EXTREMITY. 
 
 THE arm being placed at right angles with the 
 trunk, and slightly rotated outwards, make three 
 incisions through the skin : the first, along the middle of the 
 sternum ; the second, along the lower border of the clavicle and 
 down the front of the upper arm for about four inches ; the third, 
 from the ensiform cartilage, backwards, to the posterior border of 
 the axilla. 
 
 The skin should be carefully dissected from the subjacent layer 
 of subcutaneous fascia and fat. In doing so notice the thin fibres 
 of the broad subcutaneous muscle of the neck, t platysma myoides' 
 (p. 17). 
 
 CUTAKEOUS The numerous nerves which run through the 
 
 NEBVES. subcutaneous tissue to the skin and mammary 
 
 gland must be carefully dissected out. 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, 
 each with a small artery ; a third series, also branches of the inter- 
 costal 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. 19). 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. 
 
256 PECTORALIS MAJOR. 
 
 Near the sternum are found the anterior cutaneous branches 
 or terminal filaments of the intercostal nerves. After piercing 
 the pectoralis major, each nerve sends an inner filament to the 
 skin over the sternum, and an outer larger one, which supplies the 
 skin over the pectoral muscle. That of the 3d and 4th inter- 
 costal supplies also the mammary gland. 
 
 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. They are occasionally as large as the radial at the 
 wrist. 
 
 The lateral cutaneous branches of the intercostal nerves come 
 out between the digitations of the serratus magnus on the side of 
 the chest, and divide into anterior and posterior branches. The 
 anterior branches curve round the free border of the pectoralis 
 major and then supply the skin over that muscle and the mamma. 
 The posterior branches supply the skin of the back of the chest. 
 
 Dissect off the superficial fascia and fat with 
 the mammary gland. Thus you will expose the 
 strong deep fascia which is closely attached to the pectoralis major 
 and deltoid muscles. It is continuous, above, with the fascia of 
 the neck ; below, with that of the arm. At the axilla it becomes 
 denser, where it passes from the pectoral to the latissimus dorsi 
 muscles. 
 
 Reflect this fascia from the pectoralis major by dissecting 
 parallel with the course of its fibres. The muscle having been 
 fully exposed, observe its shape, the course of its fibres, their origin 
 and insertion.* 
 
 PECTORALS The pectoralis major is the large triangular 
 
 MAJOB. muscle in the front of the chest. It arises from 
 
 the sternal half of the clavicle, from the front of the sternum, 
 from the cartilages of all the true ribs except the first and the last, 
 
 * Sometimes we find a thin little muscle running perpendicularly in front of the 
 inner part of the pectoralis major. This is the rectus sternalis or sternalis brutorum. 
 It arises inferiorly by a tendinous expansion from the rectus abdominis, and is con- 
 nected above to the tendon of the sterno-mastoid. 
 
PECTOEALIS MAJOE. 257 
 
 and from the aponeurosis of the external oblique muscle of the 
 abdomen. The fibres converge 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. 
 The arrangement of its fibres, as well as the structure of its 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 ; 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. Con- 
 sequently 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 a fibrous prolongation, 
 which binds down the long head of the biceps, and is attached to 
 the great tuberosity of the humerus : another tendinous expansion 
 is prolonged backwards to the tendon of the deltoid muscle ; and 
 a third passes downwards to be 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. Thus too, on emergency, it can act as an auxiliary 
 muscle of inspiration. 
 
 Between the pectoralis major and the deltoid, the great muscle 
 covering the shoulder, is an interval varying in extent in different 
 subjects, 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. 
 
 8 
 
258 INFRA-CLAVICULAR REGION. 
 
 The pectoralis major is supplied with nerves by the anterior 
 thoracic branches of the brachial plexus ; with blood, by the long 
 and short thoracic branches of the axillary artery. 
 
 DISSECTION Eeflect the clavicular part of the pectoralis 
 
 ANATOMY OF THE major, and in doing so, notice a small nerve, the 
 INFBA-CLAVICULAR external anterior thoracic, which enters the under 
 surface of this part of the muscle. Beneath the 
 portion thus reflected, part of the pectoralis minor will be exposed. 
 In this triangle, bounded, above, by the clavicle, below, by the 
 upper border of the sternal origin of the pectoralis major, and, on 
 the outer side, by the deltoid, is an important space in which the 
 relative position of the following objects must be carefully ex- 
 amined : 
 
 COSTO-CORACOID a. A strong ligamentous expansion, called the 
 MEMBRANE. costo-coracoid membrane extends from the car- 
 
 tilage of the first rib to the coracoid process. Between these 
 points it is attached to the clavicle, and forms a complete invest- 
 ment for the subclavius muscle. Its crescent-shaped edge arches 
 over, and protects the axillary vessels and nerves; from this edge 
 is prolonged a funnel-shaped fascia, which covers the axillary 
 vessels, forming the anterior portion of their sheath ; the pos- 
 terior being formed by a prolongation of the deep cervical fascia. 
 The front portion of this sheath is perforated by the -cephalic vein, 
 the thoracica acromialis artery, and the anterior thoracic nerves. 
 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, and 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 first rib by a short 
 
 round tendon at the junction of the bone and cartilage, and is 
 
INFRA-CLAVICULAR REGION. 259 
 
 inserted into a groove on the under surface of the clavicle. Its 
 nerve comes from the fifth and sixth cervical nerves. Its 
 action is to depress the clavicle, and prevent its too great 
 elevation. 
 
 KELATIVE rosi- I n the infra-clavicular space before us are the 
 TION OF THE AXIL- great vessels and nerves of the axilla in the first 
 LAET VESSELS AND p ar ^ o f their course. They lie at a great depth 
 from the surface. They are surrounded by a 
 sheath of fascia, which descends with them beneath the clavicle. 
 Their relations with regard to each other are as follows : The 
 axillary vein lies in front of the artery, and rather to its thoracic 
 side. The brachial plexus of nerves is situated above the artery, 
 and on a posterior plane. The plexus consists of two, or sometimes 
 three, large cords, which result from the union of the anterior 
 branches of the four lower cervical, and the first dorsal, nerves. 
 The course and relations of the axillary artery will be examined 
 subsequently. 
 
 THORACIC Axis This is the first branch of the axillary artery. 
 AND BEANCHES. It 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 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 posterior circum- 
 flex, a branch of the axillary, and the supra-scapular, a branch of 
 the subclavian. A constant though small branch, the clavicular, 
 given off from this axis, runs along the anterior aspect of the sub- 
 clavius. All these arteries are accompanied by veins, which most 
 frequently empty themselves into the cephalic, but occasionally 
 into the axillary vein. 
 
 The cephalic vein is one of the principal cuta- 
 CEPHALIC VEIN. . . ~ ,, ~ . 
 
 neous veins of the arm. Commencing OD the 
 
 s 2 
 
260 INFRA- CLAVICULAR REGION. 
 
 back of the thumb and forefinger, it runs up the radial side 6f the 
 forearm, in front of the elbow-joint ; thence ascending along the 
 outer edge of the biceps, it runs up the interval between the pec- 
 toralis major and deltoid, pierces the costo-coracoid membrane, 
 and finally empties itself into the axillary vein.* 
 
 ANTEEIOR THO- These nerves come from the brachial plexus be- 
 RACIC NERVES. low the clavicle to supply the pectoral muscles. 
 There are generally two an external and an internal one for each 
 pectoral muscle. The external, the more superficial, arises from 
 the outer cord of the brachial plexus, passes over the axillary artery, 
 and supplies the pectoralis major ; the internal comes from the 
 internal cord, and runs between the axillary artery and vein, to the 
 under surface of the pectoralis minor. 
 
 ^ From this view of the relations of the axillary 
 
 DIFFICULTY OF _ J 
 
 TYING THE FIBS! artery in the first part of its course, some idea 
 PABT OF THE AXIL- may be formed of the difficulty of passing a ligature 
 LAEY ABTEBY. round it in this situation. In addition to its great 
 depth from the surface, varieties sometimes occur in the position 
 of the nerves and veins, which renders 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 con- 
 course of veins would be met with in front of the artery. Again, 
 it is by no means uncommon to find a deep-seated vein, the supra- 
 scapular, crossing over the artery to join the axillary vein. 
 
 * The cephalic vein, in some cases, runs over the clavicle to join the external 
 jugular; or there maybe a communication (termed jugulo-cephalic) between these 
 veins. 
 
AXILLAET FASCIA. 261 
 
 DISSECTION OF THE AXILLA. 
 
 SEBACEOUS On the under surface of the skin of the axilla, 
 
 GLANDS. near the roots of the hairs, are numerous sebaceous 
 
 glands. They are of a reddish-brown colour, and rather larger 
 than a pin's head. 
 
 AXILLARY FAS- This dense fascia, which lies immediately be- 
 CIA - 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. Externalty, it is strengthened by 
 fibres from the tendons of the pectoralis major and latissimus 
 dorsi, 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, is often 
 found 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. It is not a named branch, but should be remembered, 
 as it would occasion much haemorrhage if wounded in opening an 
 abscess. 
 
 DISSECTION AND Reflect the axillary fascia, to display the 
 CONTENTS OF THE boundaries and the contents of the axilla. The 
 AXILLA. dissection of this space is difficult, and must be 
 
 done cautiously. Bear in mind that the trunk blood-vessels and 
 nerves run through the upper and outer part of the axilla ; that 
 the long thoracic artery runs along the anterior border, and the 
 subscapular artery along the posterior. Commence dissecting, 
 therefore, in the middle ; break down with the handle of the 
 scalpel the loose connective tissue, fat, and lymphatic glands, which 
 occupy the cavity. You will soon discover some cutaneous nerves 
 
262 BOUNDARIES OF AXILLA. 
 
 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 digita- 
 tions 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 the mammary gland. The -posterior pass 
 backwards over the latissimus dorsi, and are distributed to the skin 
 covering this muscle and the scapula. 
 
 INTERCOSTO-HU- The posterior lateral branch of the second inter- 
 MEEAL NERVES. costal nerve requires a special description ; it is 
 larger than the others, and is called the intercosto-humeral 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 corresponding branch of the third inter- 
 costal is also an intercosto-humeral nerve. It receives a branch 
 from the second, and runs a similar course. The distribution of 
 these nerves accounts for the pain down the arm which is sometimes 
 experienced in pleurisy. 
 
 BOUNDARIES OF The axilla is a conical space, of which the 
 THE AXILLA. summit is beneath the clavicle, and the base be- 
 
 tween the pectoralis major and the latissimus dorsi. Obviously it 
 varies in capacity according to the position of the arm. On the 
 inner side, it is bounded by the four upper ribs, covered by the 
 serratus magnus ; on the outer, 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 subscapu- 
 laris. 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, bear in mind that pus may 
 burrow under the pectoral muscles, or under the scapula, or that it 
 may run up beneath the clavicle and point in the neck, if the 
 abscess be allowed to remain unopened. 
 
AXILLARY ARTERY. 263 
 
 AXILLARY LTM- The axillary glands form a continuous chain, 
 PHATIO GLANDS. beneath the clavicle,, with the cervical glands. 
 They are from ten- to twelve in number, of a reddish-brown colour, 
 and variable size. Most of them lie near some large blood-vessel ; 
 others are embedded in the loose tissue of the axilla ; sometimes 
 one or two small ones are observed along the lower border of the 
 pectoralis major. They are supplied with blood by a branch 
 thoradca alaris of the axillary artery,, and/ by branches -from the 
 thoracic and subscapular arteries. 
 
 These glands receive the lymphatics from the arm, from the 
 front and side of the chest, and from the outer half of the mam- 
 mary gland. From these glands the efferent lymphatics pass along 
 with the subclavian artery and terminate, on the. right side, in the 
 right lymphatic duct, and on the left side$ in the thoracic duct. 
 
 DISSECTION. Now reflect the pectoralis major from-, its torigin, 
 
 to expose the pectoralis minor, and the ramifications of the short 
 and long thoracic arteries. Preserve the arteries, as far as possible, 
 in connection with the main trunks. 
 
 PECTORALIS This muscle arises from the third, fourth, and 
 
 MINOR. fifth ribs, near the costal cartilages, and from the 
 
 thick fascia over the intercostal spaces. The fibres run obliquely 
 upwards 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 and biceps 
 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 .for-wards. Its nerve is derived from 
 the internal anterior thoracic; 
 
 DISSECTION. Having examined the muscles which form the 
 anterior boundary of the axilla, we pass now to the course and 
 relations of the axillary artery and its branches. To have a clear 
 view, reflect the subclavius from its insertion, and the pectoralis 
 minor from its origin. 
 
 AXILLARY AR- This artery, the continuation of the subclavian, 
 TERY, ITS COURSE takes the name of axillary at the outer border of 
 AND RELATIONS. the fj rs fc j-fa jt then passes downwards and out- 
 
264 BRANCHES OF AXILLAET ARTFRY. 
 
 wards, through the upper part of the axilla, beneath the two pec- 
 toral muscles, and along the inner border of the coraco-brachialis, 
 as far as the lower border of the tendon of the teres major, beyond 
 which it is continued under the name of the brachial. Its course 
 is divided for convenience of description into three parts : the first 
 lies above the pectoralis minor ; the second behind that muscle ; 
 and the third below it. 
 
 In the first part of its course, the artery is covered by the 
 pectoralis major and the costo-coracoid membrane, and is crossed 
 by the cephalic and acromio-thoracic veins. On its inner side, 
 and slightly in front, is the axillary vein ; on its outer side is the 
 brachial plexus of nerves ; behind it are the first intercostal space, 
 the second digitation of the serratus magnus, and the posterior 
 thoracic nerve (external respiratory of Bell). 
 
 In the second part of its course, it lies behind the pectoralis 
 major and minor ; on its inner side is the axillary vein, still 
 slightly anterior, but separated from the artery by the inner cord 
 of the brachial plexus ; on its outer side is the outer cord of the 
 brachial plexus ; and behind it is a quantity of loose connective 
 tissue which separates it from the subscapularis muscle. The 
 inner head of the median nerve is often in front of the artery in 
 this part of its course. 
 
 In the third part, in front of the artery, are the pectoralis 
 major, the two roots of the median nerve, converging like the 
 letter V, and lower down is the fascia of the arm ; on the outer 
 side are the coraco-brachialis, the musculo-cutaneous and median 
 nerves ; on the inner side are the axillary vein, the ulnar, and 
 the two internal cutaneous nerves ; behind it are in succession the 
 subscapularis, the latissimus dorsi, the teres major, and the mus- 
 culo-spiral and circumflex nerves. 
 
 BRANCHES OF The number and origin of these branches often 
 
 THK AXILLABY vary, but their general course is in most cases 
 ARTERY. similar, and they usually arise in the following 
 
 order : 
 
 a. The thoracic axis arises above the pectoralis minor, and divides 
 into branches, which have been already described (p. 259) 
 
BRANCHES OF AXILLARY ARTERY. 265 
 
 b. The alar thoracic, variable in its origin, supplies the lymphatic 
 glands and the connective tissue of the axilla. 
 
 c. The inferior or long thoracic artery (external 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. 
 
 d . 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. 
 
 The anterior branch runs along the anterior edge of the subscapu- 
 laris towards the lower angle of the scapula. Its numerous branches 
 
 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. $. Posterior circumflex. 
 5. Long thoracic. 
 
 supply the subscapularis, latissimus dorsi, serratus magnus, and teres 
 major, and anastomose with the intercostal and thoracic arteries, and the 
 posterior scapular (a branch of the siibclavian). 
 
 The posterior branch (dorsalis scapulae) runs to the back of the 
 scapula, through a triangular space, bounded in front by the long ^head 
 of the triceps ; below, by the teres major ; and above, by the subscapu- 
 lar and teres miner (diagram, p. 266). On the back of the scapula, it 
 divides into '^branches, which ramify close to the bone, supplying the infra- 
 spinatus and teres minor, and anastomose with the supra-scapular and 
 posterior scapular arteries (diagram, p. 69). The subscapular vein empties 
 itself into -the axillary vein. 
 
266 
 
 BRANCHES OF AXILLARY ARTERY. 
 
 CIRCUMFLEX 
 ARTERIES, ANTE- 
 RIOR AND POS- 
 TERIOR. 
 
 There are two circumflex arteries an anterior 
 and a posterior, so called from the manner in 
 which they encircle the neck of the humerus. 
 The posterior circumflex 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 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 
 53). It then winds round the back of the neck of the 
 
 FIG. -53. 
 
 1. Subscapularis. . 
 
 2. Teres major. 
 
 3. Long head of triceps. 
 
 4. Square space for cir- 
 
 cumflex a. and n. 
 
 5. Triangular space for dor- 
 
 salis scapulae a. 
 
 6. Space for musculo-spiral 
 
 n., and superior pro- 
 funda a. 
 
 DIAGRAM OF THE ORIGINS OF THE TRICEPS. 
 
 humerus, and is chiefly distributed to the under surface of the 
 deltoid. 
 
 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. Should you not 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. 
 
AXILLAET PLEXUS OF NERVES. 267 
 
 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, 
 and terminates in the under surface of the deltoid, where it inoscu- 
 lates with the posterior circumflex. 
 
 The anterior circumflex artery sends a small branch 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 VEIN. The axillary vein- is formed by the junction of 
 the vena3 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 venre 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. 
 
 AXILLARY OB This plexus is formed by the anterior trunks of 
 
 BRACHIAL PLEXUS the four lower cervical and first dorsal nerves, and 
 OF NEBVES. receives also a small communicating branch from 
 
 the 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 cervical nerves in the formation of the 
 plexus is variable, often not alike on both sides. The most fre- 
 quent disposition is this the fifth and sixth cervical unite to form 
 a single cord ; the eighth and the first dorsal form another cord ; 
 
 * If the axillary were tied below the pectoralis minor, the collateral circulation 
 would be established by the supra-scapular and its branches anastomosing with the 
 subscapular, the dorsalis scapulae, and the posterior circumflex : the posterior scapular 
 with the dorsalis scapulas and subscapular. 
 
268 
 
 AXILLARY PLEXUS OF NERVES. 
 
 the seventh cervical runs alone for a short distance. Each of these 
 nerves divides into an anterior and a posterior branch ; the anterior 
 branches given off from the fifth, sixth, and seventh cervical form 
 the outer cord of the plexus ; the anterior branches given off from 
 the eighth cervical and the first dorsal form the inner cord; while 
 
 Fio. 54. 
 
 THE BRACHIAL PLEXUS OF NEEVES. 
 
 c 4-8. The five lower cervical nerves. 
 D 1. The first dorsal nerve. 
 9. The rhomboid nerve to rhomboidei 
 major and minor. 
 
 10. The supra-scapular nerve to supra 
 
 and infra spinati. 
 
 11. The nerve to the subclavius. 
 
 12. Outer anterior thoracic nerve to 
 
 pectoralis major 
 
 13. Inner anterior thoracic nerve to 
 
 pectoralis minor. 
 
 14, 15, 16. The gubscapular nerves to subscapu- 
 laris, latissimus dorsi,and teres major. 
 
 17. Lesser internal cutaneous nerve. 
 
 18. Musculo-cutaneous nerve . 
 
 19. Musculo-spiral nerve or radial. 
 
 20. Median nerve. 
 
 21. Circumflex nerve to deltoid and teres 
 
 minor. 
 
 22. Ulnar nerve. 
 
 23. Internal cutaneous nerve. 
 
 24. External respiratory nerve of Bell, or 
 
 posterior thoracic. 
 
 the posterior branches of all the nerves viz., the fifth, sixth, 
 seventh, eighth cervical and the first dorsal unite to form the 
 posterior cord. 
 
BBANCHES OP AXILLAET PLEXUS. 269 
 
 The axillary plexus gives off some branches above the clavicle, 
 which were dissected with the neck (p. 72). Below the clavicle, 
 it gives off the following : 
 
 From the outer cord proceed an anterior thoracic branch, the 
 musculo-cutaneous, and the outer head of the median ; from the 
 inner cord proceed the inner anterior thoracic nerve, the inner 
 head of the median, the ulnar, the internal cutaneous, and the lesser 
 internal cutaneous ; from the posterior cord proceed the three sub- 
 scapular nerves, the circumflex and the musculo-spiral. 
 
 The anterior thoracic nerves have been described (p. 260). 
 SUBSCAPULAR The three subscapular nerves are found on the 
 
 NERVES. surface of the subscapular is. 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 (long subscapular nerve) runs with the an- 
 terior branch of the subscapular artery to the lower border of the 
 muscle. 
 
 The nerve for the teres major is either a branch of the pre- 
 ceding, or comes separately from the posterior cord. It lies nearer 
 to the humerus than the long subscapular. 
 
 The nerve of the subscapularis arises from the posterior cord 
 higher than the others, and enters the muscle not far from its 
 upper border in company with a small artery. 
 
 CIRCUMFLEX The circumflex nerve accompanies the posterior 
 
 NERVE. circumflex artery. This large nerve comes from 
 
 the posterior cord, and, after giving a small filament to the shoulder- 
 joint, passes, with its companion artery, through the quadrilateral 
 space (p. 266) to the under surface of the deltoid. Here the nerve 
 divides into an upper and a lower branch. The upper supplies 
 the anterior part of the deltoid and the skin over it ; the lower 
 supplies the back part of the deltoid, and gives the nerve to the 
 teres minor,* upon which nerve sometimes a little gangliform swell- 
 ing can be seen. After furnishing these muscular branches, the 
 nerve turns round the posterior border of the deltoid, and diverges 
 
 * This branch to the teres minor is said to be constant in all mammalia that have 
 been examined in reference to this point. 
 
270 POSTERIOR BOUNDARIES OF AXILLA. 
 
 in filaments which supply the skin over the back of this muscle 
 and over the long head of the triceps. 
 
 LATISSIMUS This muscle forms the posterior margin of the 
 
 DORSI. axilla. 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 vertebrae, and by digitations from the three lower ribs, 
 corresponding with those of the external oblique ; in some cases, 
 as it passes over the inferior angle of the scapula, it has an addi- 
 tional origin from the angle. 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. Its nerve is the long sub- 
 scapular branch of the brachial plexus. 
 
 This muscle lies behind the latissimus dorsi, is 
 TERES MAJOB. , , . , .. , . . , . , . f 
 
 closely connected with it, and assists in torming 
 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 diminish 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. Its nerve is the middle sub- 
 scapular. 
 
 This muscle arises from the internal surface of 
 the scapula, with the exception of the angles and 
 neck, and from intermuscular septa attached to the bony ridges. 
 Its fibres terminate on 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 cap- 
 sular 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. Its 
 nerve comes from the posterior cord of the brachial plexus. 
 
 SERBATUS This muscle covers the side of the chest like a 
 
 MAGNUS. girth. It arises from the eight upper ribs by 
 
 nine slips or digitations, the second rib having two. Its fibres 
 
DISSECTION OF THE UPPER ARM. 271 
 
 converge and are inserted into the posterior border of the scapula 
 in the following manner : the first two digitations are attached 
 into the upper angle of the scapular ; the third and fourth digita- 
 tions along nearly the whole length of the posterior border ; the 
 remainder are inserted into the inferior angle. Its action is to 
 draw the scapula forwards ; but of this more hereafter. It is sup 
 plied by the following nerve, which is seen on its outer surface. 
 
 This nerve supplies the serratus magnus only. 
 POSTERIOR THO- J 
 
 KACIC OK EXTER- It comes from the fifth and sixth cervical nerves ; 
 NAL RESPIRATORY and, after passing through the scalenus medius, 
 NERVE OF BELL. mng b e h m( } the axillary vessels, along the outer 
 surface of the serratus magnus, each digitation receiving a sepa- 
 rate filament.* 
 
 DISSECTION OF THE UPPER ARM. 
 
 Continue the incision down the inner side of 
 the arm as far as two inches below the elbow. 
 Keflect the skin, and trace out the cutaneous nerves, and the 
 numerous veins in front of the elbow. 
 
 CUTANEOUS On the inner side of the arm are the intercosto- 
 
 NERVES. humeral, the internal cutaneous branch of the 
 
 musculo-spiral, the internal cutaneous and the lesser internal 
 cutaneous (nerve of Wrisberg) nerves ; on the outer side are the 
 cutaneous branches of the circumflex, the external cutaneous 
 branches of the musculo-spiral, and lower down is the musculo- 
 cutaneous nerve. 
 
 The filaments of the intercosto-humeral nerves (p. 262) descend along 
 the inner and posterior part of the arm as far as the olecranon. 
 
 The branches of the internal cutaneous nerve perforate the fascia 
 about the middle of the arm, and divide into an anterior and a posterior 
 branch ; the anterior passes down in front of the arm (as a rule beneath 
 the median basilic vein), and supplies the skin as far as the wrist ; the 
 
 * It may be asked why this nerve is called the external respiratory. It was so 
 named by Sir 0. Bell, who considered the serratus magnus as the external respiratory 
 muscle, co-operating with the diaphragm or internal respiratory muscle. 
 
272 
 
 CUTANEOUS NERVES OF THE ARM. 
 
 posterior winds round to the back of the forearm behind the internal 
 condyle, and communicates with the nerve of Wrisberg and the ulnar 
 nerve. 
 
 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 the olecranon. This nerve, as it lies close to the 
 
 FIG. 55. 
 
 1. Acromial \ of the su- 
 
 branches [ perflcialcer- 
 
 2. Clavicular N^P^us. 
 
 branches / 
 
 3. Cutaneous branches of 
 
 the circumflex nerve. 
 
 4. Branches of the internal 
 cutaneous nerve. 
 
 5. External cutaneous 
 
 branch of the mus- 
 culo-spiral nerve. 
 
 6. Internalcutaneousnerve. 
 
 7. Its posterior cutaneous 
 
 branch. 
 
 8. The cutaneous branch of 
 
 the musculo-cutaneous 
 nerve. 
 
 DISTRIBUTION OF CUTANEOUS NERVES TO THE FEONT OF THE SHOULDER 
 AND ARM. 
 
 axillary vein, communicates with the first or second intercosto- humeral 
 nerve. 
 
 The internal cutaneous branch of the musculo-spiral nerve pierces the 
 fascia, and supplies the skin of the inner side of the middle of the arm. 
 
 The cutaneous branches of the circumflex nerve pierce the fascia over 
 the insertion of the deltoid, and supply the skin of the upper half of the 
 arm on its outer side. 
 
VEINS AT THE ELBOW. 
 
 273 
 
 The external cutaneous branches of the musculo-spiral nervs are two 
 in number : the upper and smaller accompanies the cephalic vein in the 
 lower half of the arm ; the lower may be traced down the outer and 
 back part of the forearm nearly as far as the wrist, where it joins the 
 musculo-cutaneous nerve. 
 
 On the outer side of the tendon of the biceps, the cutaneous branch 
 of the musculo-cutaneous nerve perforates the fascia, and divides into 
 many filaments, which supply the skin of the outer part of the fore- 
 arm. 
 
 FIG. 56. 
 
 Basilic vein ... 
 
 Median basilic vein . . 
 
 Deep median vein . . 
 
 Cephalic vein. 
 
 Median cephalic vein. 
 
 Median vein. 
 
 SUPERFICIAL VEINS AND NERVES AT THE BEND OF THE LEFT ELBOW. 
 
 DISPOSITION OF 
 VEINS IN FRONT OF 
 THE ELBOW. 
 
 Attention should now be directed to the dis- 
 position of the veins in front of the elbow. In 
 cleaning these veins, take care not to divide the 
 branches of the internal and external cutaneous nerves which pass 
 over and under them. 
 
 The following is the ordinary arrangement of the superficial 
 
 T 
 
274 VEINS AT THE ELBOW. 
 
 veins at the bend of the elbow (fig. 56). On the outer side is the 
 radial ; on the inner side is the ulnar vein, formed by the junction 
 of the anterior and posterior ulnar cutaneous veins ; 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 bifur- 
 cation, 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 
 border of the biceps to the groove between the pectoralis major and 
 the deltoid, where it terminates in the axillary vein. 
 
 The basilic vein ascends along the inner side of the arm with 
 the internal cutaneous nerve. Near the upper third of the arm, 
 it perforates the fascia, and empties itself either into the in- 
 ternal vena comes of the brachial artery or into the axillary 
 vein. 
 
 The principal branches of the cutaneous nerves 
 KELATION OF r 
 
 THE CUTANEOUS P ass beneath the veins : that is to say, as a rule, 
 NERVES AND VEINS the internal cutaneous passes behind the median 
 AT THE ELBOW. basilic vein, and the external cutaneous behind 
 the median cephalic : but it should be remembered that many 
 small filaments cross in front which are exposed to injury in 
 venesection. 
 
 Since the median basilic vein is larger than the 
 KELATION OF 
 
 MBDIAN BASILIC median cephalic, and, on account of the strong 
 VEIN TO BEA- fascia beneath, more easily compressible, it is 
 CHIAL AKTEEY. usually chosen for venesection ; its position, there- 
 fore, in reference to the brachial artery, becomes important. 
 The vein is only separated from the artery by the semilunar fascia, 
 derived from the tendon of the biceps. This fascia is in some 
 subjects remarkably thin. Sometimes the artery lies above the 
 fascia, in 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 
 
FASCIA OP THE ARM. 275 
 
 from the median basilic above the situation where it crosses the 
 brachial artery. 
 
 LYMPHATIC Immediately above the internal condyle, in the 
 
 GLANDS. neighbourhood of the basilic vein, we find one or 
 
 two small lymphatic glands. Others may be higher up along the 
 inner side of the arm. A gland is occasionally met with at the 
 bend of the elbow ; but never below this joint. These little glands 
 are the first which are liable to become tender and enlarged after 
 a poisoned wound of the hand. 
 
 MUSCULAB ^ ne f asc i a which invests the muscles of the 
 
 FASCIA AND ITS upper arm is a continuation of the fascia of the 
 CONNECTIONS. 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. 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 humerus 
 and to the condyles. The internal intermuscular 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 intermuscular 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 extensor behind. 
 
 At the lower part of the upper arm, the fascia is remarkably 
 strong, especially where it covers the brachialis anticus, and the 
 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. 
 
 T 2 
 
276 MUSCLES OF THE ARM. 
 
 Now remove the fascia in order to see the 
 
 Dl* SECTION 
 
 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 
 BICEPS ' 
 
 heads a long and a short. The short head 
 
 arises from the point of the coracoid process of the scapula, by 
 a thick, flat tendon in common with a slender muscle on its 
 inner side, called the coraco-brachialis. The long head arises 
 from the upper border of the glenoid fossa of the scapula and 
 the glenoid ligament, by a long, rounded tendon, which, tra- 
 versing the shoulder-joint, 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 synovial 
 membrane of the joint is reflected round the tendon, and accom- 
 panies it for about two inches down the groove, thus forming a 
 synovial fold. The object of this is to facilitate the play of the 
 tendon, and to carry little arteries (from the anterior circum- 
 flex) for its supply. The two heads unite about the middle of the 
 arm, and form a single muscle, which terminates on a strong flat 
 tendon of considerable length ; this dips down 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 bursa intervenes to diminish 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 
 forearm. 2. It is a powerful supinator of the forearm, in conse- 
 quence of its insertion into the posterior part of the tubercle of 
 the radius. Its power of supination is greatest when the forearm 
 
MUSCLES OF THE ARM. 277 
 
 is half 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 dislocated 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 a branch from the brachial, 
 which runs into the middle of its inner side and divides into 
 ascending and descending branches. Its nerve comes from the 
 musculo-cutaneous. 
 
 COBACO-BBA- This thin muscle is situated at the upper part 
 
 CHIAIIS. of the arm, and 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 on 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. It is supplied by a branch from the musculo-cuta- 
 neous nerve which passes through it. 
 
 Concerning the coraco-brachialis remember, 1 . That the mus- 
 culo-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. 
 
 * See a preparation in the Museum of St. Bartholomew's Hospital, ser. v. 9. 
 
278 BRACHIAL ARTERY. 
 
 BRACHIALIS This muscle is situated upon the lower half of 
 
 ANTICUS. the humerus, and is partially concealed by the 
 
 biceps. Between the two muscles is the musculo-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 lower half of the front sur- 
 face of the bone, and from the intermuscular septa. The muscle, 
 becoming thicker and broader, covers the front of the capsule of the 
 elbow-joint to which it is more or less attached, and terminates 
 on a tendon, which is inserted in a pointed manner into the coro- 
 noid process of the ulna. Its action is to bend the forearm. Its 
 nerves come from the musculo-cutaneous. Sometimes the brachialis 
 anticus receives in addition a small branch from the musculo- 
 spiral. 
 
 Now examine the course and relations of the brachial vessels 
 and nerves. 
 
 COURSE AND BE- The brachial artery the continuation of the 
 LATIOXS OF THE axillary takes its name at the lower border of 
 BRACHIAL ARTERY. ^] ie teres major. It runs down the inner side of 
 the arm, along the inner border of the coraco-brachialis and 
 biceps, to about an inch below 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 
 deepest part of the axilla to the middle 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. 
 
BEACHIAL AETEEY. 279 
 
 The ulnar nerve runs along the inner side of the artery as far 
 as the middle of the arm. Below this point, the nerve leaves the 
 artery, and passes through the interamscular septum to get behind 
 the internal condyle. 
 
 Superficial to the artery, are the internal cutaneous nerve and 
 the basilic vein. 
 
 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 ; the inner borders of these muscles, in their respective 
 situations, being 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, provided the 
 pressure be made in the proper direction namely, outwards ; here, 
 too, it is crossed by the median nerve. 
 
 At the bend of the elbow the artery is crossed by the semi- 
 lunar fascia from 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. To compress 
 the artery here, pressure should be made directly backwards. 
 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 
 contact with the brachial artery, and communicate at frequent 
 intervals by transrerse branches. Near the axilla they join and 
 form the axillary vein. 
 
 BEANCHES OF The brachial artery gives off three branches, 
 
 BRACHIAL AETEET. all from its inner side : namely, the superior 
 profunda, the inferior profunda, and the anastomotica magna. 
 It also distributes muscular branches (to the coraco-brachialis 
 and biceps), which are given off from its outer side. 
 
 a. The profunda superior arises from the brachial artery, immedi- 
 ately below the tendon of the teres major.* It winds round the hack of 
 * If the profunda be not in its usual plao'e, look for it above the tendon of the 
 
280 
 
 BEACHIAL ARTEKY. 
 
 the humerus, between the outer and inner heads of the triceps, accom- 
 panied by the musculo-spiral nerve, 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 
 
 FIG. 57. 
 
 Eaperior profunda . . . . 
 
 Interosseous recurrent . . 
 
 Hadial recurrent 
 
 Posterior interosseous . . . 
 
 Inferior profnnda. 
 
 Anastomotica magna. 
 
 Anterior ulnar recurrent. 
 Posterior ulnar recurrent. 
 
 Common interosseous. 
 Anterior interosseous. 
 
 PLAN OF THE CHIEF BRANCHES OF THE BRACHIAL AETEHY AND THE ABTEEIAL 
 INOSCULATIONS ABOUT THE BIGHT ELBOW-JOINT. 
 
 triceps muscle, with the nerve to the anconeus, as far as the olecranon, 
 and anastomoses with the posterior ulnar recurrent, the interosseous re- 
 current, and anastomotica magna arteries : the other branch accompanies 
 
 latissimus dor*i, where it will probably be given off from a common trunk -with the 
 posterior circumflex. 
 
BEACHIAL ARTERY. 281 
 
 the mus3ulo-spiral nerve to the outer side of the arm, where it perforates 
 the external inter muscular septum. It then 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, others behind it, to inosculate with the radial and inter- 
 osseous recurrent arteries. 
 
 Before its division, the superior profunda sends several branches to 
 the triceps, some of which inosculate with the circumflex. These assist 
 in establishing a collateral circulation when the brachial artery is ligatured 
 above the origin of the profunda. 
 
 b. The profunda inferior arises from the brachial, opposite to the in- 
 sertion 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), passes through the internal inter- 
 muscular septum, and then descends to the interval between the internal 
 condyle and the olecranon, inosculating with the posterior ulnar recurrent 
 and anastomotica magna arteries. 
 
 The nutrient artery of the humerus arises sometimes from the brachial, 
 sometimes from the interior profunda. It pierces the tendon of the 
 coraco-brachialis, runs obliquely downwards through the bone, and in the 
 medullary canal divides into ascending and descending branches, which 
 anastomose with the nutrient vessels of the bone derived from the peri- 
 osteum. 
 
 c. The anastomotica magna arises from the inner side of the brachial, 
 about two inches above the elbow, runs tortuously inwards across the 
 brachialis anticus, and divides into branches, some of which pass in front 
 of the internal condyle, anastomosing with the anterior ulnar recurrent 
 artery; others pass behind the internal condyle and anastomose with the 
 inferior profunda and posterior ulnar recurrent arteries; and one branch 
 forms an arch, above the olecranon fossa, with the superior profunda. 
 
 d. Numerous muscular branches arise from the outer side of the 
 brachial artery ; one of these, the bicipital, 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. 
 
 The two veins which accompany the brachial 
 
 artery are continuations of the deep radial and 
 
 ulnar veins. The internal is usually the larger, and generally 
 
 receives the veins corresponding to the principa branches of the 
 
282 NEEVES OF THE UPPEE AEM. 
 
 artery. In their course they are connected at intervals by trans- 
 verse 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 comes internet,, which then 
 takes the name of axillary. 
 
 Now trace the great nerves of the upper arm, which proceed 
 from the brachial plexus near the tendon of the subscapularis : 
 namely, the median, the musculo-cutaneous, the ulnar, and the 
 musculo-spiral or radial. 
 
 The median nerve arises by two roots, which 
 
 MEDIAN NERVE. - - , M1 / <?,i\ 
 
 converge in tront ot the axillary artery (p. 2b4). 
 
 The external root is derived from a trunk in common with the 
 musculo-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 (in some cases under) the 
 vessel, 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.* 
 
 * I hare 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 situa- 
 ted 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: 
 
NERVES OF THE UPPER ARM. 283 
 
 As a summary of the distribution of the median nerve, we may 
 say that it supplies the two pronators and all the flexors of the 
 forearm (except the flexor carpi ulnaris and the ulnar half of the 
 flexor profundus digitorum) ; the muscles of the ball of the thumb, 
 the two radial lumbricales, both sides of the thumb, fore and 
 middle fingers, and the radial side of the ring finger. 
 
 MUSCUT.O-CUTA- This nerve (often called the external cutaneous) 
 NEOUS NERVE, arises in common with the external root of the 
 median from the external cord of the brachial plexus behind the 
 pectoralis minor, and is situated on the outer side of the axillary 
 artery. It perforates the coraco-brachialis obliquely, 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, pass- 
 ing under the median cephalic vein, divides into branches, for the 
 supply of the integuments of the forearm. 
 
 The musculo-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 small filaments to supply the elbow-joint. 
 
 This nerve arises from the inner cord of the 
 
 brachial 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 
 
 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. 
 
 * In some instances the musculo-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 musculo-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 ) y the median, which is larger than usual. Such 
 anomalies are easily explained by the fact of the two nerves having a common origin. 
 
284 NERVES OF THE UPPEE ARM. 
 
 coraco-brachialis. The nerve then diverges from the artery, per- 
 forates the internal intermuscular septum, and runs with the in- 
 ferior profunda artery, behind the internal condyle. 
 
 The distribution of the nerve is to the flexor carpi ulnaris, to 
 half the flexor profundus digitorum, to all the interosseous muscles 
 of the hand, to both sides of the little finger, to the ulnar side of 
 the ring finger, to the muscles of the ball of the little finger, to 
 the two ulnar lumbricales, and, lastly, to the adductor pollicis, 
 and the inner head of the flexor brevis pollicis. 
 
 Previous to the examination of the musculo-spiral nerve, we 
 should examine the great muscle which occupies the whole of the 
 posterior part of the humerus viz. the triceps extensor cubiti. 
 
 TRICEPS EXTEN- This muscle has three distinct origins, named 
 SOE CuBin. from their position, the external, the internal, and 
 
 the middle or long heads (p. 266). 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, 
 beginning in a pointed form immediately below the insertion of 
 the teres minor, and extending as low down as the musculo-spiral 
 groove. The internal head arises from the humerus below the 
 insertion of the teres major, from the posterior surface of the bone 
 below the musculo-spiral groove, and from the internal inter- 
 muscular septum. 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. Each head is supplied by a 
 separate branch from the musculo-spiral nerve. 
 
 MUSCULO-SPI- This, the largest of the brachial nerves, arises, 
 
 EAL NEETE. in common with the circumflex, from the posterior 
 
 cord of the axillary plexus (p. 268). 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 perforates the 
 external intermuscular septum, and then runs deeply embedded 
 between the brachialis anticus and the supinator radii longus. 
 
DISSECTION OF THE FOREARM. 285 
 
 The nerve gives off branches on the inner side of the humerus, 
 to the inner and long heads of the triceps ; on the back of the 
 humerus, to the external head of the triceps and the anconeus ; on 
 the outer side of the humerus, to the supinator radii longus, the 
 extensor carpi radialis longior, and the brachialis anticus (some- 
 times) ; lastly, after perforating the septum, it gives off the upper 
 and lower external cutaneous branches. 
 
 A little above the elbow-joint the nerve divides into its two 
 principal branches the radial, which accompanies the radial 
 artery along the forearm and the posterior interosseous, which 
 perforates the supinator brevis, and supplies the muscles on the 
 back of the forearm. 
 
 To sum up the muscular distribution of this great nerve, we 
 may say that it supplies all the extensors of the forearm, wrist, 
 thumb, and fingers ; and all the supinators except one namely, 
 the biceps (supplied by the musculo-cutaneous nerve). 
 
 DISSECTION OF THE FKONT OF THE FOREARM. 
 
 Prolong the incision down to the wrist, and, at 
 its termination, make another transversely. Ee- 
 flect the skin, and dissect the subcutaneous veins and nerves. 
 
 CUTANEOUS O n the inner side is the anterior ulnar vein, 
 
 VEINS. which commences on the front of the 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. 273). 
 
 The veins on the back of the hand commence at the extremi- 
 ties of the fingers, run up betiveen the knuckles, and unite on the 
 back of the hand, forming an arch, with its concavity upwards. 
 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, 
 
286 FASCIA OP THE FOREAEM. 
 
 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. 
 
 Running up in front of the middle of the forearm is the median 
 vein ; near the bend of the elbow it is joined by a deep branch 
 mediana pro/undo, 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 (fig. 56). 
 
 CUTANEOUS On the radial side of the forearm, as low down 
 
 NEKVES. as the wrist, are found the terminal filaments of 
 
 the anterior branch of the musculo-cutaneous nerve, which, about 
 the middle of the forearm, sends a branch backwards to supply the 
 posterior and lower part of the forearm as low as the wrist, commu- 
 nicating with the radial and external cutaneous branch of the 
 musculo-spiral. At the lower part of the forearm, one or more 
 of these filaments are situated over the radial artery. 
 
 In front of the upper part of the forearm are some filaments 
 of the external cutaneous branch of the musculo-spiral nerve ; on 
 the outer and back part of the forearm, near the elbow, the lower 
 external cutaneous branch of the musculo-spiral runs down as far 
 as the wrist to supply the skin. 
 
 At the lower third of the radial side of the forearm, the radial 
 nerve becomes superficial, and turns over the radius to supply the 
 back of the hand and fingers. 
 
 On the ulnar side the anterior division of the internal cuta- 
 neous nerve descends as far as the wrist ; its posterior branch 
 passing to the back of the forearm to supply it as far as the middle. 
 Near the styloid process of the ulna, the dorsal branch of the 
 ulnar nerve perforates the fascia to reach the back of the hand. 
 
 DEEP FASCIA OF The muscles of the forearm are enveloped by a 
 THE FOREARM. dense shining aponeurosis, continuous with that 
 of the arm. Its thickness increases towards the wrist, that 
 the tendons, in this situation, may be kept 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 
 
MUSCLES OF THE FOREARM. 287 
 
 back of the wrist, it forms the posterior annular ligament, and in 
 front, it 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 mus- 
 cular fibres in the upper part of the forearm, and furnishes septa 
 which separate the muscles, and form surfaces for their origin. 
 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. 
 
 TKIANGLE AT At the bend of the elbow is a triangular space, 
 
 THE ELBOW. with its base towards the humerus ; on the inner 
 
 side this space is bounded by the pronator teres ; on the outer, by 
 the supinator radii longus. In it are the following objects, which 
 must be carefully dissected : 1. In the centre is 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 side is the median nerve ; 4, the musculo- 
 spiral nerve is partly concealed by the supinator longus ; 5, the 
 radial recurrent artery ; 6, the anterior ulnar recurrent ; 7, the 
 common interosseous branch of the ulnar artery; 8, the vena 
 mediana profunda. 
 
 MUSCLES OF The muscles of the forearm are arranged in two 
 
 THE FOREARM. groups ; one, consisting of supinators and exten- 
 sors, 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 sublimis digitorum. 
 
288 MUSCLES OF THE FOREARM. 
 
 PBONATOR This muscle forms the inner boundary of the 
 
 EADH TEKES. triangular space at the elbow. It arises from the 
 
 anterior surface of the internal condyle, from the common tendon, 
 from the fascia of the forearm, and from the septum between it 
 and the flexor carpi radialis. It has also a small tendinous origin 
 from the inner border of 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. Its nerve comes from the median. 
 
 FLEXOR CARPI This muscle arises by the common tendon from 
 EADIALIS. the internal 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, bridged over by 
 fibrous tissue and lined by a synovial membrane, and is inserted 
 into the base of the second metacarpal bone. The outer border of 
 its tendon is the guide to the radial artery in the lower half of the 
 forearm. Its nerve comes from the median. 
 
 PALMARIS This slender muscle arises from the common 
 
 LONGUS. tendon at the internal condyle, from the inter- 
 
 muscular septa, and from the fascia of the forearm. About the 
 middle of the forearm it terminates in a flat tendon, which de- 
 scends along the middle of the forearm to the wrist, lying upon 
 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.* Its nerve comes from 
 the median. 
 
 FLEXOE CABPI This muscle arises by two heads : one from the 
 
 ULNARIS. internal condyle, the common tendon, and the 
 
 * The palmaris longus is absent in about one out of ten subjects. The situation 
 of its muscular portion is subject to variety ; sometimes occupying the middle, some- 
 times the lower third of the forearm. The tendon is in some instances wholly inserted 
 into the anterior annular ligament. 
 
MUSCLES OP THE FOEEAEM. 289 
 
 intermuscular septum ; the other 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 aponeurosis, 
 which is common to this muscle and the flexor profundus digi- 
 torum. 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 metacarpal bone. Its nerve comes from the 
 ulnar. 
 
 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. 
 
 FLEXOE SUBLI- This muscle is situated beneath those previously 
 MIS DIGITORUM. mentioned, and has two distinct origins. The 
 longer origin takes place from the internal condyle, from the in- 
 ternal lateral ligament, the common tendon, the iutermuscular 
 septa, and the coronoid process of the ulna ; the shorter origin 
 takes place by tendinous and fleshy fibres from an oblique ridge oil 
 the front of the radius, extending from the tubercle to about an 
 inch below the insertion of the pronator teres. This, called its 
 radial origin, is partly concealed 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 annular ligament, arranged in two 
 pairs ; the tendons of the middle and ring fingers being placed 
 over those of the fore and little fingers. The tendons pass through 
 the palm to the fingers, where they split to allow the passage of 
 the deep flexor tendons, and are inserted into the sides of the 
 second phalanges. Its action is, therefore, to bend the second 
 joint of the fingers. 
 
 The muscles described as arising from the internal condyle are 
 all supplied by the median nerve, except the flexor carpi ulnaris, 
 which is supplied by the ulnar. 
 
 u 
 
290 RADIAL AETEEY. 
 
 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 tracing the vessels and nerves of the 
 forearm. 
 
 SUPINATOR This muscle forms the external boundary of the 
 
 EADH 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, and from the external intermuscular septum. The mus- 
 cular fibres 'terminate about the middle of the forearm in a flat 
 tendon, which is inserted into the outer side of the base of the 
 styloid 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. It is supplied 
 by the musculo- spiral nerve. 
 
 The radial artery, the smaller division of the 
 brachial, 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 angle between the first and second metacarpal bones to 
 form the deep palmar arch. Thus, its course corresponds with a 
 line drawn from the middle of the bend of the elbow, to the front 
 of the styloid process of the radius. 
 
 In the upper third of the forearm, the artery lies deep 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 supi- 
 nator longus on the outer and the flexor carpi radialis on the inner 
 side. In its course, it lies successively on the following : first, 
 upon the tendon of the biceps ; secondly, upon the supinator radii 
 brevis ; thirdly, upon the insertion 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 
 the lower end of the radius. The artery then crosses the wrist joint, 
 lying upon the external lateral ligament ; next, it lies upon the 
 
RADIAL ARTERY. 291 
 
 trapezium ; and, lastly, passing between the two heads of the first 
 dorsal interosseous muscle, it enters the palm to form the deep 
 palmar arch. It is accompanied by two veins, which communicate 
 at frequent intervals, and join the venae comites of the brachial 
 artery at the bend of the elbow. 
 
 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 usually 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 lies 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. 
 
 a. The radial recurrent is given off just below the elbow ; it ascends 
 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 inoscula- 
 tion with the superior profunda (p. 280). 
 
 b. The arteria superficialis voice arises from the radial, about half an 
 inch, or more, above the lower end of the radius : it runs over the an- 
 terior 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.* 
 
 c. The anterior carpal artery is a small branch of the radial, which 
 runs beneath the tendons, and supplies the anterior surface of the synovial 
 membrane and bones of the carpus, anastomosing with the anterior inter- 
 osseous, the anterior carpal branch of the ulnar, and the recurrent carpal 
 branch of the deep palmar arch. 
 
 * There is great variety in the size and origin of the superficialis volae ; some- 
 times 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. 
 
 TJ 2 
 
292 ULNAE AETEEY. 
 
 d. The posterior carpal artery runs beneath the extensor tendons, and 
 joins the corresponding branch of the ulnar to form an arch ; it also 
 anastomoses with the anterior interosseous artery on the back of the wrist. 
 
 e. Small muscular branches are also given off by the radial artery in 
 its course down, the forearm. 
 
 The radial nerve, a branch of the musculo- 
 
 EADIAL NERVE. .',.-. ~ , ,11 i f .-, 
 
 spiral, is given on above the bend of the elbow, 
 
 deep between the supinator radii longus and brachialis anticus ; it 
 descends on 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, lying to its outer side ; 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 becomes subcutaneous. It then divides into two 
 branches ; an outer, which supplies the skin of the ball of the 
 thumb, and communicates with the musculo-cutaneous nerve ; and 
 an inner, which generally supplies both sides of the dorsal aspects 
 of the thumb, of the index and middle fingers, and of the radial 
 side of the ring finger. 
 
 This artery, the larger of the two divisions of 
 the 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 
 inosculating 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, namely, 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 comes nearer the surface, and descends 
 between the flexor sublimis 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 profundus digitorum. 
 
TJLNAR ARTERY. 293 
 
 The ulnar nerve is at first separated from the artery by a con- 
 siderable interval : 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 situa- 
 tion. 
 
 Observe that the ulnar artery, in the lower third of its course:, 
 lies under the radial border of the tendon of the flexor carpi 
 ulnaris, which is the surgical guide to the vessel. The artery is 
 accompanied by two veins, which join the venae comites of the 
 brachial. 
 
 The ulnar artery gives off the following branches in the fore- 
 arm : 
 
 a. The anterior and posterior ulnar recurrent arteries arise immediately 
 below the elbow-joint, sometimes by a common trunk. The anterior 
 passes upwards 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 pro- 
 fundus 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 inferior profunda, the anasto- 
 motica magna, and, above the olecranon, with the posterior interosseous 
 recurrent (p. 280). 
 
 b. The common interosseous artery is about half an inch long. It arises 
 from the ulnar, just below the tubercle of the radius, and soon divides into 
 the anterior and posterior interosseous, which we shall examine pre- 
 sently. 
 
 c. The carpal branches are given off j ust above the pisiform bone : 
 the posterior carpal runs beneath the extensor tendons, and forms, 
 with the corresponding branch of the radial artery, an arch, from 
 which are usually given off the second and third dorsal interosseous ar- 
 teries : these anastomose with the perforating arteries. The anterior 
 carpal runs in front of the carpus, supplies the synovial membrane and 
 the ligaments, and anastomoses with the anterior carpal from the radial. 
 
 d. Muscular branches are also distributed from the trunk of the ulnar 
 artery in its course. 
 
294 MEDIAN NERVE IN THE FOREARM. 
 
 This nerve runs behind the internal condvle, 
 ULNAR NERVE. . . f ,-, a . , . 
 
 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 digi- 
 torum. About the middle of the forearm, the nerve joins the 
 ulnar artery, and runs along its inner side over the anterior annular 
 ligament into the palm. 
 
 The uluar nerve, as it lies behind the elbow, gives off some 
 filaments to the joint. It supplies branches to the flexor carpi 
 ulnaris, and to the ulnar half of the flexor profundus digitorum. 
 It also gives off a small cutaneous branch, which accompanies the 
 ulnar artery to the palm. 
 
 About two inches above the styloid process of the ulna, the 
 nerve gives off, to the back of the hand, its dorsal cutaneous 
 branch, which is of considerable size. This 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 back of the little ringer, 
 and half the ring finger ; here also it sends a branch which com- 
 municates with the corresponding branch of the radial nerve. 
 
 This nerve, at the bend of the elbow, lies on the 
 
 MEDIAN NERVE. . . 
 
 inner side ot the brachial artery. It then passes 
 between the two origins of the pronator teres, and descends along 
 the middle of the forearm, between the flexor sublimis and the 
 flexor profundus digitorum. At the lower part of the forearm, it 
 becomes more superficial, lying about the middle of the wrist, be- 
 tween the outer tendon of the flexor sublimis, 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, 
 
 * 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. 
 
FLEXOR PROFUNDUS DIGITORUM. 295 
 
 except the flexor carpi ulnaris and the ulnar half of the flexor pro- 
 fundus, which are supplied by the ulnar nerve. The anterior 
 interosseous nerve, a branch of the median, runs with the anterior 
 interosseous artery, close to 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 cutaneous palmar branch, which passes over the 
 ligament, and divides into small filaments to supply the skin of the 
 palm and ball of the thumb, communicating with the cutaneous 
 palmar branches of the ulnar, the external cutaneous, and the radial. 
 
 Now reflect the superficial layer of muscles, to 
 DISSECTION. ,, i i j. j T> .L-U 
 
 see those more deeply seated. .Preserve the prin- 
 cipal 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. 
 
 FLEXOR PRO- This * s the thickest muscle of the forearm. It 
 
 FTJNDUS DIGITO- arises from the upper two-thirds of the anterior 
 EUM - surface of the ulna, from the same extent of its 
 
 internal surface, from the aponeurosis attached to the posterior 
 edge of the ulna, and from the inner two-thirds of the interosseous 
 membrane. 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 superficial 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. It derives its nerves from the interosseous 
 branch of the median and the ulnar. 
 
 FLEXOB. LONGUS This muscle is situated on the front surface of 
 POLLICIS. the radius, outside the preceding. It arises from 
 
 the front surface of the radius, between the tubercle and the pro- 
 nator quadratus, and from the interosseous membrane.* Its tendon 
 * Sometimes by a slip from the coronoid process. 
 
296 AXTEBIOB IXTEBOSSEOUS ARTEBY. 
 
 proceeds beneath the annular ligament to the base of the last 
 phalanx of the thumb. Its nerve comes from the interosseous 
 branch of the median. 
 
 PROXATOR This square muscle arises from the lower fourth 
 
 QVADRATTS. of the ulna ; its fibres pass some transversely, some 
 
 obliquely outwards, and are inserted into the lower fourth of the 
 radius. It pronates the radius on the ulna. Its nerve proceeds 
 from the interosseous branch of the median. 
 
 ANTERIOR CSTKR- Nearly on a level with the insertion of the 
 OSSBOCS ARTERY. biceps, the ulnar artery gives off from its outer 
 side the common interosse&us, which runs backwards for about 
 half an inch, and divides into the anterior and posterior inter- 
 osseous. 
 
 The anterior interosseous artery runs close to the interosseous 
 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 be- 
 hind 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 more important, perforates the inter- 
 osseous membrane, and helps to supply the muscles on the back of 
 the forearm. 
 
 A branch, the arteria comes nervi mediani, proceeds from the anterior 
 interosseous. It lies in close contact with the nerve, sometimes in its 
 very centre : though usually of small size, it may be as large as the ulnar 
 artery itself, and, in such cases, it passes under the annular ligament 
 with the nerve to join the palmar arch. This is interesting, 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 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 forearm, to supply the 
 medullary membrane. 
 
 ASTKRIOR ra- This nerve is a branch of the median ; it gene- 
 
 TEROSSBOCS rally runs close to the radial side of the artery, 
 
 and supplies the flexor longus pollicis, half the 
 flexor profundus digitorum, and the pronator quadratus. 
 
PALM OP THE HAND. 
 
 DISSECTION OF THE PALM OF THE HAND. 
 
 I)i 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 an 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, the palmar 
 branch of the ulnar, supplies the inner aspect of the hand. 
 
 PALMABIS This small cutaneous muscle is situated on the 
 
 BEEVIS. inner side of the palm. It arises from the inner 
 
 edge of the central palmar fascia, and is inserted into 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 inner edge of the palm and deepens the hollow of it, forming 
 the so-called 'cup of Diogenes.' It is supplied by the ulnar nerve. 
 This fascia has a silvery lustre, and, in the 
 
 PALMAR FASCIA. . J 
 
 centre of 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 
 
298 PALM OF THE HAND. 
 
 deep surface of the fascia two septa dip down, and 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 completely 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. 
 
 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. 
 
 B.eneath the interdigital folds of the skin, there are apo- 
 neurotic fibres to strengthen them, constituting what are called the 
 transverse ligaments of the fingers. They form a continuous liga- 
 ment 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, so as to expose the vessels, nerves, and tendons 
 
 in the palm. The vessels lie above the nerves, and the tendons 
 
PALM OF THE HAND. 
 
 299 
 
 still deeper. There is an abundance of loose connective tissue to 
 allow the free play of the tendons. When suppuration takes place 
 in the palm, it is seated in this tissue. Eeflect for a moment 
 what mischief is likely to ensue. The pus cannot come to the 
 
 FIG. 58. 
 
 Radial artery . 
 
 Supcrficialis vote 
 
 Arteria magna 
 pollicis . . 
 
 Radialis indicia . 
 
 Ulnar artery. 
 
 Ulnaris profumla. 
 
 DIAGRAM OF THE SUPERFICIAL AND DEEP PALMAR ARCHES. 
 
 1, 2,' 3, 4. Interosseous branches. 
 
 surface through the dense palmar fascia, or on the back of the 
 hand ; it will therefore run up into the carpal bursa under the 
 annular ligament, and make its way deep amongst the tendons of 
 the forearm. 
 
300 PALM OP THE HAND. 
 
 SUPERFICIAL The ulnar artery, having passed over the annular 
 
 PALMAR AHCH. ligament, 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 indicis, to form the superficial palmar arch. 
 The curve of the arch is directed towards the fingers, its greatest 
 convexity descending as low as a horizontal line drawn across the 
 junction of the upper with the middle third of the palm. 
 
 In its passage over the annular ligament, the artery lies in the 
 furrow, between the pisiform and unciform bones, and is protected 
 by an expansion from the tendon of the flexor carpi ulnaris to the 
 palmaris longus. The ulnar nerve lies close to the inner side of 
 the artery, both being covered by the palmaris brevis. 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 
 and the divisions of the ulnar and median nerves ; and is covered 
 by the palmar fascia. 
 
 BRANCHES OF Immediately below the pisiform bone, the ulnar 
 
 THE ULNAE AB- artery gives off the ulnaris profunda, which sinks 
 TEHY IN THE deeply into the palm, between the abductor and flexor 
 
 ALM ' brevis minimi digiti, to form the deep palmar arch, by 
 
 joining the terminal branch of the radial artery. It is accompanied by 
 the deep branch of the ulnar nerve. 
 
 From the concavity of the arch small recurrent branches ascend to 
 the carpus, and inosculate with the other carpal branches of the radial 
 and ulnar arteries. 
 
 Four digital arteries arise from the convexity of the arch. They 
 supply all the fingers, except the radial side of the index finger. 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 
 with 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 at the tip of the finger. 
 
PALM OF THE HAND. 801 
 
 In the palm of the hand the digital arteries, before they divide, 
 are joined by branches from the corresponding palmar interosseous 
 arteries (branches of the deep palmar arch) (fig. 58). 
 
 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 which supply the matrix of the 
 nail. 
 
 ULNAR NERYE The ulnar nerve passes over the annular liga- 
 IN THE PALM. ment into the palm, on the inner side of the 
 
 ulnar artery, and a little behind it. It lies in the groove between 
 the pisiform and unciform bones, so that it is perfectly secure from 
 pressure. Immediately below the pisiform bone, the nerve divides 
 into a superficial and a deep palmar branch. The deep branch 
 supplies the muscles forming the ball of the little finger, and 
 accompanies the ulnaris profunda artery into the palm, to supply 
 all the interosseous muscles, the two inner lumbricales, the adductor 
 pollicis, and the inner head of the flexor brevis pollicis. The super- 
 ficial branch sends filaments to the palmaris brevis, to the skin on 
 the inner side of the palm, and then divides into two digital nerves, 
 one for the supply of the ulnar side of the little finger, the other 
 for the contiguous sides of the little and ring fingers. This branch 
 also communicates with the median nerve behind the superficial 
 palmar arch. All the digital branches run along the sides of the 
 fingers to their extremities superficial to their corresponding 
 arteries. 
 
 ANTERIOR AN- This exceedingly strong and thick ligament con- 
 HULAR LIGAMENT fines the flexor tendons of the fingers and thumb, 
 OF THE CARPUS. an( j fastens together the bones of the carpus. It 
 is attached, externally, to the scaphoid and trapezium ; inter- 
 nally, to the pisiform and unciform. Its upper border is con- 
 tinuous with the aponeurosis in front of the wrist ; its lower is 
 connected with the palmar fascia ; its anterior surface receives the 
 expanded tendon of the palmaris longus, and gives origin to most 
 of the muscles of the ball of the thumb and little finger. 
 
302 PALM OP THE HAND. 
 
 Cut vertically through the ligament, and ob- 
 
 DlSSECTION. . ' - 
 
 serve 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 superficial 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 contained in a distinct sheath, lined by a 
 separate synovial membrane, formed, partly by the annular liga- 
 ment, and, partly, by the groove in the trapezium. 
 
 MEDIAN NERVE In its passage under the annular ligament, the 
 IN THE PALM. median nerve is enveloped in a fold of synovial 
 
 membrane, and lies upon the flexor tendons. Here it divides 
 into two nearly equal parts ; the external gives 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 
 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 digital branches which supply 
 the inner side of the forefinger, both sides of 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 outer one being connected with a 
 terminal filament of the radial. 
 
 . 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 between 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 lurabricales ; 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 
 
PALM OF THE HAND. 303 
 
 digital artery passes and bifurcates lower down ; therefore a vertical in- 
 cision 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- 
 tributed to the skin around and beneath the matrix of the nail. 
 Each digital nerve terminates in the cushion at the end of the 
 finger in a brush of filaments, with their points directed into the 
 papillae of the skin. 
 
 FLEXOH TEN- Immediately below the annular ligament the 
 
 DONS AND THEIB tendons separate from each other : near the meta- 
 SHEATHS. carpal joints they pass in pairs, through strong 
 
 fibrous rings (p. 298) formed by the divisions of the palmar fascia. 
 Below the metacarpal 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 par- 
 ticular 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 
 
 * UpoD the cutaneous nerves of the hand and feet are 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 fa 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. These bodies are found in many other situa- 
 tions, viz., in the solar plexus, the pudic nerves, the intercostal nerves, the cutaneous 
 nerves of the arm and neck, the infra-orbital nerve, the sacral plexus, and in nerves 
 supplying the periosteum. They can be best examined in the mesentery of the cat. 
 
304 PALM OP THE HAND. 
 
 stronger between the joints than over the joints themselves. 
 Through these sheaths, inflammation commencing in the integu- 
 ments of the ringer may readily extend to the synovial membrane 
 of the tendon. 
 
 In cases of whitlow, when pus 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 be- 
 comes stiff.* 
 
 But what protects the joints of the fingers where the flexor 
 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 fibro- 
 cartilaginous structure, called the '-palmar ' 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 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 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 
 
 * 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 annularia ' are situated immediately in front of the joints, and may be 
 considered as thin continuations of the ligamenta vaginalia. They consist of fibres, 
 which are attached on either side to the lateral ligaments of the joints, and pass 
 transversely over the tendons. 
 
PALM OP THE HAND. 305 
 
 below the deep tendon so as 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 superficial one, is inserted 
 into the base of the last phalanx.* 
 
 In what way are the tendons supplied with blood ? Kaise and 
 separate the tendons, and you will see that slender but very vas- 
 cular folds of synovial membrane (vincula teudinum) run up from 
 the phalanges and convey blood-vessels to the tendons. 
 
 The tendon of the flexor longuspollicis 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 the base 
 of the last phalanx. Its synovial sheath is prolonged from the large 
 bursaof the flexor ten dons beneath the annular ligament, and accom- 
 panies the tendon down to the last joint of the thumb ; conse- 
 quently the sheath is injured in amputation of the last phalanx. 
 
 BUBSAL SAC OF A large and loose synovial sac (bursa of the car- 
 THE CABPUS. p ns ) 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 understand that, when 
 the bursa is inflamed and distended by fluid, there will be a bulg- 
 ing above the annular ligament, and another in the palm, with 
 perceptible fluctuation between them ; the unyielding ligament 
 causing a constriction in the centre, f 
 
 * In the Museum of the College of Surgeons, a preparation is put up which shows 
 a beautiful piece of animal mechanics concerning 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 increases the leverage 
 in each case. 
 
 f In only one subject have we seen an instance in which this bursa communicated 
 
 X 
 
306 PALM OF THE HAND. 
 
 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 also 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 dorsal aspect 
 of the first phalanx 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 were called by 
 the old anatomists ' fidicinales.' 
 
 The two inner lumbricales are supplied by the deep branch of 
 the ulnar nerve; the two outer by the third and fourth digital 
 branches of the median. 
 
 Now proceed to the muscles composing the ball of the thumb 
 and the little finger. The dissection of them requires consider- 
 able care. 
 
 MUSCLES OF The g rea t strength of the muscles of the ball 
 
 THE BALL OF of the thumb (unde nomen pollicis), is one of the 
 
 THE THUMB. distinguishing 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 namely, an abductor, an opponens, 
 two flexors, three extensors, and an adductor. 
 
 ABDUCTOR This is the most superficial. It is a thin, flat 
 
 POLLICIS. muscle, and arises from the ridge of the os tra- 
 
 pezium and the annular ligament. It 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. Its nerve comes from 
 the median. Keflect it from its insertion to expose the follow- 
 ing : 
 
 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. For this reason, inflammation 
 of the theca of the thumb or little finger is more liable to be attended with serious 
 consequences than either of the others. 
 
PALM OP THE HAND. 307 
 
 OPPONENS POL- This muscle arises from the os trapezium be- 
 LICIS - neath the abductor, and from the annular ligament, 
 
 and is inserted into the whole length of the radial side of the meta- 
 carpal bone of the thumb. The action of this powerful muscle 
 is to oppose the thumb to all the fingers. Its nerve comes from 
 the median. Reflect it from its insertion, to expose the follow- 
 ing : 
 
 FLEXOR BREVIS This muscle has two origins ; one, the super- 
 POLLICIS. ficial, from the annular ligament and os trapezium ; 
 
 the other, the deep, from the os trapezoides, os magnum, and the 
 bases of the second and third metacarpal bones. It is inserted by 
 two strong tendons into the base of the first phalanx of the 
 thumb ; the superficial tendon being connected with 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. The superficial portion is supplied by the 
 median nerve ; the deep, by the ulnar. 
 
 ADDTJCTOB POL- This muscle arises from the palmar aspect of 
 LICIS. the shaft of the metacarpal bone of the middle 
 
 finger ; its fibres converge and are inserted, along with the deep 
 or 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 The muscles of the little finger correspond in 
 BALL OF THE some measure with those of the thumb. Thus 
 
 LITTLE FINGEB. there is an abductor, a flexor brevis, and an op- 
 ponens minimi digiti. All derive their nerves from the deep 
 branch of the ulnar. 
 
 ABDUCTOB This, the most superficial of the muscles of the 
 
 MINIMI DIGITI. little finger, arises from the pisiform bone, and 
 
 x 2 
 
308 PALM OP THE HAND. 
 
 from the tendinous expansion of the flexor carpi ulnaris : it is 
 inserted by a flat tendon into the inner side of the base of the first 
 phalanx of the little finger. Its action is to draw this finger 
 from the others. Its nerve comes from the deep branch of the 
 ulnar. 
 
 FLEXOR BREVIS This slender muscle may be considered as a 
 MINIMI DIGITI. portion of the 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. Nerve 
 from deep branch of ulnar. 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. 
 
 OPPONBNS The last two muscles must be reflected from 
 
 MINIMI DIGITI. their insertion, to expose the opponens minimi 
 digiti. It arises from the unciform process and the annular 
 ligament, and is inserted along the ulnar side of the shaft of the 
 metacarpal bone of the little finger. Its action is to draw this 
 bone, the most movable of all the metaearpal bones of the fingers, 
 towards the thumb. Thus it greatly strengthens the grasp of the 
 palm. Nerve from deep branch of ulnar. 
 
 Now cut through all the flexor tendons, and 
 DISSECTION. . 
 
 remove the deep fascia of the palm, to see the 
 
 deep arch of arteries and its branches. 
 
 B , The radial artery, sinking into the space be- 
 
 THE RADIAL AR- tween the first and second metacarpal bones, enters 
 TERT IN THE the palm between the inner head of the flexor 
 
 PALM - brevis and the adductor pollicis, and gives off 
 
 three branches the arteria princeps pollicis, the radialis indicis, 
 and the palmaris profunda, which unites with the ulnar to form 
 the deep arch. 
 
 The arteria princeps 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 digital branches, which proceed one on either 
 side of the thumb, and inosculate at the apex of the last phalanx. Their 
 
PALM OF THE HAND. 309 
 
 distribution and mode of termination are like 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 end, 
 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 may be considered as the continuation 
 of the radial artery. It enters the palm between the inner head of 
 the flexor brevis and the adductor pollicis, and, running upon the 
 bases of the metacarpal bones, 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 three or four small branches, called 
 palmar interosseous (fig. 58. p. 299), 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 consider- 
 able size, and take the place of one or more of the digital arteries, ordi- 
 narily derived from the superficial palmar arch. Three branches, called 
 perforating, 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. 
 
 DEEP BBANCH This nerve sinks into the palm with the ulnaris 
 
 OF THE ULNAR profunda artery, between the abductor and flexor 
 NKRVE. brevis minimi digiti. It then runs with the deep 
 
 palmar arch towards the radial side of the palm, and terminates 
 in the adductor pollicis, and the inner or deep 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 base of the second metacarpal 
 bone. 
 
310 SUPERFICIAL MUSCLES OP THE BACK. 
 
 The dissection of the remaining muscles of the palm, called, 
 from their position, interossei, 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 outwards 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 cutaneous nerves. 
 
 CUTANKOUS These are derived from the posterior divisions 
 
 NEBVES OF THE of the 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, are derived those which supply 
 the skin of the lower dorsal and lumbar regions. In the cervical 
 and upper dorsal region, the cutaneous nerves perforate the com- 
 plexus, 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 descend over the crest 
 of the ilium, and terminate in the skin of the buttock. 
 
 Among these cutaneous nerves, notice, at this stage of the dis- 
 section, the following : 
 
 1. The posterior branch of the second cervical nerve is called 
 the great occipital. It perforates the complexus, and ramifies on 
 the back of the scalp with the occipital artery. 
 
 2. The posterior branch of the third cervical nerve sometimes 
 sends a branch to the back of the scalp. 
 
SUPERFICIAL MUSCLES OF THE BACK. 311 
 
 3. The posterior branch of the second dorsal nerve is the largest 
 of all the dorsal cutaneous nerves. It runs outwards and ramifies 
 in the skin over the spine of the scapula. 
 
 4. The posterior branch of the second lumbar nerve comes 
 through the fascia lumborum near the posterior superior spine of 
 the ilium, and runs over the crest of that bone to supply the skin 
 of the buttock. 
 
 ^ The trapezius and latissimus dorsi, which form 
 
 DISSECTION. r 
 
 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 occi- 
 put ; from the ligamentum nuchae,* from the spines of the seventh 
 cervical, and all the dorsal vertebrae, and from their supra-spinous 
 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 acromion 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 
 muscles are connected by a thin aponeurosis over the spine and 
 acromion. If both the trapezius muscles be exposed, observe that, 
 between the sixth cervical and the third dorsal vertebras, their 
 origin presents an aponeurotic space of an elliptical form. 
 
 The structures covered by the trapezius are, the splenius, the 
 complexus, the levator anguli scapulas, the rhomboidei minor and 
 major, the supra-spinatus, a small part of the infra-spinatus, the 
 longissimus dorsi, the sacro-lumbalis, the spinal accessory nerve, 
 and the superficialis colli artery. 
 
 * 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 vertebrae, except the atlas ; otherwise it 
 would impede the free rotation of the head. In the giraffe this ligament is six feet 
 long, and ae thick as a man's forearm. Professor Quekett states that when divided it 
 shrinks at least two feet. 
 
312 SUPERFICIAL MUSCLES OF THE BACK. 
 
 The fixed point of the muscle being at the vertebral column, 
 all its fibres tend to raise the shoulder. The deltoid cannot raise 
 the humerus beyond an angle of ninety degrees : beyond this, the 
 elevation of the arm is principally effected by the rotatory move- 
 ment of the scapula. The trapezius 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 only acts, it draws the head to the same 
 side. It is supplied by the nervus accessorius and the cervical 
 plexus, and by the superficial! s colli artery. 
 
 LATISSIMUS This broad flat muscle occupies the lumbar and 
 
 DORSI. lower dorsal region, and thence extends to the 
 
 arm, 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 fleshy 
 slips, which interdigitate 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 and higher than that 
 of the teres major, from which it is separated by a large bursa.* 
 It is supplied mainly by the long subscapular nerve, also by the 
 posterior branches of the dorsal and lumbar nerves. 
 
 The latissimus dorsi draws the humerus inwards and back- 
 wards ; rotating it also inwards. It 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 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 
 
 * The latissimus dorsi frequently receives a distinct accessory slip from the inferior 
 angle of the scapula. 
 
SUPERFICIAL MUSCLES OF THE BACK. 813 
 
 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.* 
 
 The muscles lying beneath the latissimus dorsi are, a small 
 part of the rhomboideus major, of the infra-spinatus, and of the 
 teres major, the serratus posticus inferior, the spinalis dorsi, the 
 longissimus dorsi, the sacro-lumbalis, and the external intercostals. 
 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. Im- 
 mediately 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. 
 
 LUMBAB This dense shining aponeurosis of the back 
 
 APONEUBOSIS. (sometimes termed the aponeurosis of the latissi- 
 
 mus dorsi) forms the posterior part of the sheath of the erector 
 spinse. It is pointed above, where it is continuous with the deep 
 cervical fascia, broader and stronger below. It consists of ten- 
 dinous fibres, which are attached internally to the spines of the six 
 or seven lower dorsal, all the lumbar and sacral vertebrae ; exter- 
 nally, to the angles of the ribs ; and inferiorly it is blended with 
 the tendons of the serratus posticus inferior and latissimus dorsi. 
 When suppuration takes place in the loins, constituting a lumbar 
 abscess in connection with spinal disease, the pus is seated 
 beneath this aponeurosis, and is therefore tardy in coming to the 
 surface. 
 
 Reflect the trapezius from its insertion. On its 
 
 DISSECTION. 
 
 under surface see the ramifications of its nutrient 
 artery, the superficialis colli, a branch of the posterior scapular. 
 A large nerve, the spinal accessory, enters its under surface near 
 
 * We hare seen several instances of this displacement. There is great projection 
 of the inferior angle of the scapula, especially when the patient attempts to raise the 
 arm. He cannot raise the arm beyond a right angle, unless firm pressure is made 
 on the lower angle of the scapula, so as to supply the place of the muscular strap. 
 Whether the scapula can be replaced or not, a firm bandage should be applied round 
 the chest. 
 
314 SUPERFICIAL MUSCLES OF THE BACK. 
 
 the clavicle, and divides into filaments, which, reinforced by fila- 
 ments from the third and fourth cervical nerves, are distributed 
 to the muscle as far as its lower border. 
 
 SPINAL ACCES- This nerve is one of the three divisions of the 
 
 SORT NERVE. eighth 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. 19). 
 
 Beneath the trapezius we have to examine the second layer, 
 consisting of three muscles connected with the scapula ; namely, 
 the levator anguli scapulae, the rhomboideus major and minor. 
 The scapula should be adjusted so as to stretch their fibres. 
 
 LEVATOR AN- This muscle is situated at the side of the neck. 
 
 GULI SCAPULA. It 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 along 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 cervical. 
 
 EHOMBOIDEUS These flat muscles extend from the spinous pro- 
 
 MAJOR AND cesses of the vertebrae to the base of the scapula. 
 
 MINOR. They often appear like a single muscle. The 
 
 rhomboideus minor, the higher of the two, arises by a thin apo- 
 neurosis from the spinous processes of the last cervical and the first 
 dorsal vertebra, and is inserted into the base of the scapula oppo- 
 site 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 larger number of the fibres being 
 
SUPRA-SCAPULAR ARTERY. 315 
 
 inserted into a tendinous arch, which is chiefly attached to the 
 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 
 branch of the fifth cervical. It passes outwards beneath the lower 
 part of the levator anguli scapula, to which it sends a branch, and 
 is lost in the under surface of the rhomboidei. 
 
 This muscle extends from the scapula to the 
 
 OMO-HTOIDEUS. . . 
 
 os hyoides, and consists ot two long narrow mus- 
 cular portions, connected by an intermediate tendon beneath the 
 sterno-mastoid. The posterior portion only can be seen in the 
 present dissection. It arises from the upper border of the scapula, 
 close behind the notch, and from the ligament above the notch. 
 Thence the slender muscle passes forwards across the lower part of 
 the neck, beneath the sterno-mastoid, where it changes its direc- 
 tion and ascends nearly vertically, to be attached to the os hyoides 
 at the junction of the body with the greater cornu (p. 29). Thus 
 the two portions 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 (p. 30). 
 
 SUPKA-SCAPU- This artery (transversalis humerj), a branch of 
 
 LAB AETEET. the thyroid axis (p. 67), runs behind and parallel 
 
 with the clavicle, over the lower end of the acalenus 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 scapulae, a branch of the subscapular. It 
 sends off 
 
 a. The supra-acromial branch, which ramifies upon the acromion, 
 anastomosing with the other acromial arteries derived from branches of 
 the axillary ; b. a small subscapular branch to the fossa of the same 
 
316 SERRATUS MAGNUS. 
 
 name ; c. articular arteries to the shoulder joint ; and, lastly, d. the 
 infra-spinous branch, which anastomoses with the dorsalis scapulas. 
 The supra-scapular vein terminates either in the subclavian or in the 
 external jugular. 
 
 The supra-scapular nerve, a branch of the fifth, and some- 
 times the 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. 
 
 POSTERIOR This artery is one of the divisions of the trans- 
 
 SCAPULAR versalis colli, but comes very frequently from the 
 
 ARTERY. subclavian in the third part of its course (p. 67). 
 
 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 pursues 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 inser- 
 tion, and trace the artery to the inferior angle 
 of the scapula, where it terminates in the rhomboidei, serratus 
 inagnus, and latissimus dorsi. 
 
 Numerous muscular branches arise from the posterior scapular. 
 The superficialis colli (the other division of the transversalis colli) 
 is given off near the upper angle of the scapula for the supply of 
 the trape/ius. 
 
 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 inagnus, than was 
 seen in the axilla. The abundance of connective tissue in this 
 situation is necessary for the play of the scapula on the chest. 
 
 SERRATUS This broad flat muscle intervenes between the 
 
 MAGNUS. scapula and the ribs. It arises by nine fleshy 
 
 digitations from the eight upper ribs, each rib giving origin to one, 
 and the second to two. The four lower digitations correspond with 
 
MUSCLES OP THE SHOULDEK. 317 
 
 those of the external oblique muscle of the abdomen. All the 
 fibres pass backwards, and converge to be inserted along the inner 
 side of 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 
 anatomists ascribe to it the power of raising the ribs ; hence Sir 
 Charles Bell called it the external respiratory muscle, the in- 
 ternal respiratory muscle being the diaphragm. 
 
 The nerve which supplies it is a branch of the fifth and sixth 
 cervical nerve : it descends along its outer surface^ distributing a 
 filament to each digitation of the muscle (p. 271). 
 
 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 insertions of the preceding 
 muscles. 
 
 DISSECTION OF THE MUSCLES OF THE SHOULDEK. 
 
 Dissect first the cutaneous nerves of the 
 DISSECTION. 
 
 CUTANEOUS shoulder ; these are derived, partly from the 
 
 NERVES OF THE acromial branches of the cervical plexus which 
 SHOULDEK. descend over the acromion (fig. 59), 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 
 deltoid, which extends from the aponeurosis covering the muscles 
 
318 
 
 THE DELTOID. 
 
 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 large muscle which covers the shoulder- 
 joint is named deltoid, from its resemblance to the 
 Grreek A reversed. It arises from the external third of the 
 clavicle, from the acromion, and from the spine of the scapula 
 
 FIG. 59. 
 
 DELTOID. 
 
 1. Supra-acromial br. of the 
 
 cervical nerves. 
 
 2. Ascending and descend- 
 
 ing brs. of the circum- 
 flex n. 
 
 3. 4. Cutaneous brs. of the 
 
 musculo-cutaneous n. 
 
 5. Internal cutaneous br. of 
 musculo-spiral n. 
 
 6. Intercosto-humeral 
 
 brs. 
 
 7. Filaments of the lesser 
 
 internal cutaneous n. 
 
 8. Posterior cutaneous 
 
 br. of internal cuta- 
 neous n. 
 
 9. Branch of internal cu- 
 
 taneous n. 
 
 CUTANEOUS NERVES OF THE LEFT SHOULDER AND ARM. (POSTERIOR VIEW.) 
 
 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 aponeurosis. The muscular fibres descend, the .an- 
 terior backwards, the posterior forwards, the middle perpendicu- 
 larly ; all converge to a tendon which is inserted into a rough 
 
THE DELTOID. 
 
 319 
 
 surface on the outer side of 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 V-shaped form, the 
 origin of the brachialis anticus embracing it on either side. 
 Sometimes a few fibres of the pectoralis major are connected with 
 its front border. 
 
 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 arrangement better than any 
 description. The action of the muscle is not only concentrated 
 upon one point, but its power is also greatly increased by this 
 arrangement. 
 
 ACTION OF THE It raises the arm ; but it cannot do so beyond 
 DELTOID. an angle of ninety degrees. The elevation of the 
 
 arm beyond this angle is effected through the raising of the 
 shoulder by the trapezius and ser- 
 ratus magnus. Its anterior fibres 
 draw the arm forwards ; its pos- 
 terior, backwards. 
 
 This powerful muscle is supplied 
 with blood, by the anterior and 
 posterior circumflex, the thoracica 
 humeraria, the thoracica acromi- 
 alis, all from the axillary artery ; 
 also by the deltoid branch of the 
 brachial. Its nerve is the circumflex. 
 
 The rotundity of the shoulder is 
 due not so much to the deltoid as 
 to the upper end of the humerus. 
 When the head of the humerus is 
 dislocated into the axilla, the fibres 
 of the muscle run vertically to 
 their insertion; hence the flatten- 
 ing of the deltoid, and the greater prominence of the acromion. 
 
 FIG. 60. 
 
 ANALYSIS OF THE DELTOID. 
 
320 CIRCUMFLEX AETERT AND NERVE. 
 
 It is below the deltoid that an ununited fracture of the 
 humerus is most commonly met with, owing to the muscle dis- 
 placing the upper fragment. 
 
 Eeflect the deltoid from its origin, and turn it 
 downwards. Observe the ramifications of the 
 circumflex nerve and the anterior and posterior circumflex 
 arteries, on its under surface : notice also the large bursa between 
 it and the tendons inserted into the great tuberosity of the 
 humerus. The muscle covers the coraco-acromial ligament, the 
 head, neck, and upper part of the humerus, as well as the coraco- 
 brachialis and biceps, the pectoralis minor, the supra-spinatus, the 
 infra-spinatus, and teres minor, the subscapularis and the long 
 head of the triceps. 
 
 BURSA UNDUE The large bursa under the deltoid extends for 
 
 THE DELTOID, OR some distance beneath the acromion and the 
 SUB-ACROMIAL. coraco-acromial ligament, and covers the tendons 
 attached to the great tuberosity of the humerus. It communi- 
 cates, very rarely, with the shoulder-joint. Its use is to facilitate 
 the movements of the head of the bone under the acromial arch. 
 
 POSTERIOR This artery is given off from the axillary : it 
 
 CIRCUMFLEX runs behind the surgical neck of the humerus, 
 
 ARTERY. through a quadrilateral opening, 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 (p. 266). 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. 
 
 CIRCUMFLEX This nerve, a branch of the posterior cord of the 
 
 NERVE. axillary plexus, runs with the posterior circumflex 
 
 artery. It sends a branch to the teres minor, one or two to the 
 integuments of the shoulder, and terminates in the substance of 
 
MUSCLES OF THE SCAPULA. 321 
 
 the deltoid. The proximity of this nerve to the head of the 
 humerus explains the occasional paralysis of the deltoid, after dis- 
 location or fracture of the humerus. The nerve is liable to be 
 injured, if not actually lacerated, by the pressure of the bone. 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 completely 
 across.* 
 
 A strong aponeurosis covers the muscles of the dorsum of the 
 scapula, and is 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. 
 
 I NFRA . This muscle arises from the posterior two-thirds 
 
 SPINATUS. of the infra-spinous fossa, and from the aponeu- 
 
 rosis 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 
 middle depression on the greater tuberosity of the bumerus. Its 
 nerve comes from the supra-scapular. 
 
 This long narrow muscle is situated below the 
 TBEES MINOE. . ~ . , , , . ,. . , , ~ , , 
 
 mfra-spmatus, along the inferior border of the 
 
 scapula. It arises from the dorsum of the scapula, close to 
 the inferior border, and from the intermuscular septa between it 
 and the infra-spin atus above and the teres major below. The 
 fibres ascend parallel with those of the infra- spinatus, and termi- 
 nate 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-like enlargement upon it. 
 
 The action of the infra-spinatus and teres minor is to rotate 
 the humerus outwards. 
 
 * See preparation in Museum of St. Bartholomew's Hospital, series 3, No. 42. 
 
 Y 
 
MUSCLES OF THE SCAPULA. 
 
 This muscle is closely connected with the latis- 
 simus dorsi, and extends from the inferior angle 
 of the scapula to the immerus, 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, from its inferior border, 
 and the intermuscular septa, and terminates upon a flat tendon, 
 nearly two inches in breadth^ which is inserted into the inner 
 edge of the bicipital groove of the humerus, behind and a little 
 lower than the tendon of the latissimus dorsi. Its action is to 
 draw the humerus backwards. It is supplied by the middle sub- 
 scapular nerve. 
 
 A bursa is found in front of, and another behind the tendon of 
 the teres major; t-he former separates it from the latissimus dorsi, 
 the latter from the bone. 
 
 SUPRA- This muscle arises from the posterior two-thirds 
 
 SMNATUS. of the supra-spinous fossa, and-from its aponeurotic 
 
 covering. It passes under the acromion, over the shoulder-joint, 
 and is inserted by a strong tendon into the superior depression of 
 the greater tuberosity 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 stibscapular fossa. It 
 
 SUBSCAPULARIS. , , 
 
 arises from the posterior three-fourths ot the 
 fossa, and from three or four tendinous septa attached to the 
 oblique bony 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 in- 
 sertion is closely connected with the capsule of the shoulder-joint, 
 which it completely protects upon its inner side. Its action is to 
 rotate the humerus inwards. The nerves which supply it come 
 from the long and middle subscapular nerves. 
 
 The coracoid process, with the coraco-brachialis and short head 
 of the biceps, forms an arch, under which the tendon of the sub- 
 scapularis plays. There are several bursce about the tendon. 
 
TEICEPS EXTENSOR CUBITI. 323 
 
 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. 
 
 Now reflect the muscles from the surfaces of the 
 
 scapula, to trace the arteries which ramify upon it. 
 
 CONTINUATION This artery, a branch of the thyroid axis, runs 
 
 OF SDPRA-SCAPU- under and parallel with the clavicle, and passes 
 
 LAB ARTERY AND above the notch of the scapula, into the supra- 
 
 spinous fossa : it sends a branch to the supra- 
 
 spinatus, another to the shoulder-joint, and then descends behind 
 
 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, sup- 
 plies the supra-spinatus with two branches, and then enters the 
 infra-spinous fossa, to terminate in the infra-spinatus. 
 
 DORSALIS This artery, after passing through the triangular 
 
 SCAPULA ARTERY, space (p. 266), curves round the inferior border of 
 the scapula, which it grooves, to the infra-spinous fossa, where it 
 ascends close to the bone, and anastomoses with the supra and 
 posterior scapular arteries. 
 
 The several communications about the scapula between the 
 branches of the subclavian and axillary arteries, would furnish a 
 large collateral supply of blood to the arm, if the subclavian were 
 tied above the clavicle (p. 69). 
 
 TRICEPS EXTEN- This muscle, which arises by three heads, and 
 SOR CUBITI. was on iy partially seen in the dissection of the 
 
 upper arm (p. 284), should now be thoroughly 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 external head arises from the 
 posterior part of the humerus, below the insertion of the teres 
 
 Y 2 
 
324 TRICEPS EXTENSOR CUBITI. 
 
 minor, as far as the musculo-spiral groove. The internal head 
 arises from the posterior part of the humerus, below the teres 
 major and the musculo-spiral groove, as far as the olecranon fossa ; 
 it has an additional origin from the internal intermuscular septum, 
 and from a small portion of the external. The precise origin 
 of these heads from the humerus, may be ascertained by following 
 the superior profunda artery and musculo-spiral nerve, which 
 separate 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 con- 
 nected with the fascia on the back of the forearm. The effect of 
 this connection is that the same muscle which extends the fore- 
 arm tightens the fascia which gives origin to the extensors of the 
 wrist and fingers. The same holds good in the case of the biceps, 
 and its semi-lunar expansion in the fascia of the forearm. 
 
 Between the tendon and the 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 the 
 subcutaneous one, which is situated 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 por- 
 tion, it will be seen 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 sub-anconeus ; 
 their use is to draw up the capsule, so that it may not be injured 
 during extension of the arm. The sub-anconeus is in this respect 
 analogous to the sub-eruraeus 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 anasto- 
 motica magna (fig. 61, p. 334). 
 
 Trace the continuation of the superior profunda artery (p. 279) 
 and museulo-spiral nerve round the posterior part ef the humerus. 
 They lie in a slight groove on the bone,* between the external 
 
 * It is worth remembering that the nerve may be injured by a fracture of the 
 humerus in this situation, and even by too tight bandaging ; the result being para- 
 lysis of the extensor muscles of the forearm. 
 
DISSECTION OP THE BACK OF THE FOREARM. 325 
 
 and internal heads of the triceps, and are protected by an aponeu- 
 rotic arch, thrown over them by the external head of the triceps. 
 After supplying the muscles, the artery continues its course 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- 
 osseous and radial nerves. The small nerve must be made out 
 which runs down the substance of the triceps, accompanied by a 
 branch from the superior profunda artery, to supply the anconeus. 
 The cutaneous branches of the musculo-spiral nerve have been 
 already dissected (p. 272). 
 
 DISSECTION OF THE BACK OF THE FOREARM. 
 
 SUBCUTANEOUS Remove the skin from the back of the forearm, 
 
 BUES^E. hand, and fingers, and make out the subcutaneous 
 
 bursa over the olecranon. It is of considerable size, and, if dis- 
 tended, would appear nearly as large as a walnut. Another bursa 
 is sometimes found a little lower down upon the ulna. A sub- 
 cutaneous 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 some- 
 times 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. 273). 
 
 The cutaneous nerves of the back of the fore- 
 
 (JUTANEOUS 
 
 NEBVES OF THE arm, are derived from the external cutaneous 
 BACK OF THE branches of the musculo-spiral, from branches of 
 
 FOREABM. ^e i^nial cutaneous, and of the external cuta- 
 
 * The brachialis anticus usually receives a branch from the musculo.^piral nerve. 
 
326 DISSECTION OF THE BACK OF THE FOKEAEM. 
 
 neous. The greater number of these nerves may be traced down 
 to the back of the wrist. 
 
 The skin on the back of the hand is united to 
 NERVES ON THE 
 
 BACK OF THE the subjacent tendons by an abundance of loose 
 
 HAND AND connective tissue, in which are large veins, and 
 
 FINGERS, branches of the radial and ulnar nerves. The 
 
 dorsal branch of the ulnar nerve passes beneath the tendon of 
 the flexor carpi ulnaris, over the internal lateral ligament of the 
 wrist, and divides upon the back of the hand into filaments, 
 which supply both sides of 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 filaments, which supply both sides of the back 
 of the thumb and forefinger, and the radial side of the middle 
 finger.* 
 
 The radial nerve commonly gives off, on the back of the hand, 
 a branch which joins the nearest branch of the ulnar. 
 
 FASCIA ON BACK The fascia on the back of the forearm is com- 
 OF FOREARM. posed 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 ex- 
 pansion 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 divides 
 them by septa, to which their fibres are also attached. 
 
 POSTERIOR This ligament should be considered as a part of 
 
 ANNULAR LIGA- the fascia of the forearm, specially strengthened 
 MENT - by oblique aponeurotic fibres on the back of the 
 
 wrist, to confine the extensor tendons. These fibres are attached 
 
 * 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 com- 
 munications 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 
 ft branch from the palmar nerve. 
 
DISSECTION OP THE BACK OF THE FOREARM. 327 
 
 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. 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. - 
 
 SEPARATE From the deep surface of the posterior annular 
 
 SHEATHS FOE ligament, processes are attached to the ridges on the 
 
 EXTENSOR back of the radius so as to form six ^distinct -sheaths 
 
 for the passage of the extensor-tendons. Commenc- 
 ing 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 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. Occasionally, but 
 not often, one or more of them communicate with the; wrist- 
 joint. 
 
 The fascia of the metaearpus 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, 
 DISSECTION. >!- 1 i fi -, i 
 
 without injuring the muscular fibres which arise 
 
 from its under surface. Preserve the posterior annular ligament. 
 The following superficial muscles are now exposed, and should be 
 examined in the order in which they are placed, proceeding from 
 the radial to the ulnar side: 1. The supinator radii longus 
 SUPERFICIAL (already described, p. 290). 2. The extensor carpi 
 MUSCLES ON THE radialis longior. 3. The extensor carpi radialis 
 BACK OF THE brevior. 4. The extensor communis digitorum. 
 
 FOREARM. 5 ^ The extensor m i n i m i digiti. 6. The extensor 
 
 carpi ulnaris. 7. The anconeus. 
 
328 DISSECTION OF THE BACK OP THE FOREARM, 
 
 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 namely, the ex- 
 tensor 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. 
 
 EXTENSOR This muscle is partly covered by the supinator 
 
 CARPI BADIALIS radii longus. It arises from the lower third of 
 LONGIOR. {.jj e ridge leading to the external condyle of the 
 
 humerus, and from the intermuscular septum. It 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 
 
 CARPI RADIALIS by the tendon common to it and the other ex- 
 BRETIOR. tensors, from the inter-muscular septa, and 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 radralis longior, beneath the three 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 
 
DISSECTION OF THE BACK OF THE FOREARM. 329 
 
 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. 
 
 EXTENSOR DIGI- This muscle arises from the common tendon 
 TOKUM COMMUNIS. attached . to the external condy le, from the septa 
 between it and the contiguous 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 the tendons become broader and flatter, and 
 diverge from each other towards the metacarpal joints of the 
 ringers, where they become thicker and narroAver, 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 
 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 the 
 second phalanx, are inserted into the upper end of the third.* Its 
 nerve comes from the posterior interosseous. 
 
 The oblique aponeurotic slips which connect the tendons on 
 the back of the hand 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 finger usually receives a slip from 
 that of the ring. 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. Thus the ring finger 
 does not admit of independent extension. 
 
 * The extensor tendons are inserted into the periosteum ; but 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. It probably also 
 explains the great liability to necrosis which is so frequently observed in cases of 
 thecal abscess. 
 
330 DISSECTION OF THE BACK OP THE FOREARM. 
 
 The muscle is not only a general extensor of the fingers, but 
 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. 
 
 EXTENSOR This long slender muscle, situated on the inner 
 
 MINIMI DIGITI OB side of the common extensor, arises from the 
 AURICUIARIS. common tendon from the external condyle, and 
 
 from the septa between it and the contiguous muscles. Its slender 
 tendon runs separately beneath the annular ligament immediately 
 behind the joint between the radius and ulna, in a special sheath 
 lined by sy no vial 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, terminating in the 
 same manner as the extensor tendons of the other fingers. Its 
 nerve comes from the posterior interosseous. 
 
 EXTENSOR This muscle arises from the common tendon 
 
 CARPI ULNARIS. from the external condyle, from the septum be- 
 tween it and the extensor minimi digiti, and from the aponeurosis 
 of the forearm. The fibres terminate upon a strong broad tendon, 
 which traverses a distinct groove on the back of the ulna, close to 
 the styloid process, and is inserted into the posterior aspect of 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 ligament, over the back of the wrist, and is confined in a 
 very strong fibrous canal, which is attached to the back of the 
 cuneiform, pisiform, and unciform bones, and is lined by a continu- 
 ation from the synovia! 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 
 
DISSECTION OF THE BACK OF THE FOREARM. 331 
 
 by a strong layer of fascia, derived from the tendon of the triceps, 
 and appears like a continuation of that muscle. It arises by 
 a tendon 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 
 DISSECTION. ,, , , , , ,, 
 
 from the external condyle the extensor carpi 
 
 radialis brevior, the extensor communis digitorum, the extensor 
 minimi digiti, and the extensor carpi 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 dissected. The muscles exposed are : 
 
 1. The extensor, ossis metacarpi pollicis. 2. EX- 
 DEEP-SEATED . 11. r 
 MUSCLES ON THE tensor primi internodii pollicis. 3. Extensor se- 
 
 BACX OF THE cundi internodii pollicis. 4. Extensor indicis or 
 
 FOREARM. indicator. 5. The supinator radii brevis. They 
 
 are all supplied by branches fronv the posterior interosseous nerve. 
 
 EXTENSOR This musc l e arises from the posterior surface of 
 
 Ossis METACARPI the ulna below the supinator brevis, from the 
 POLLICIS. posterior surface of the radius, and from the inter- 
 
 osseous membrane. The muscle crosses the radial extensors of the 
 wrist about three inches above the carpus, and terminates in a 
 tendon, which passes along a common groove with the extensor 
 primi internodii pollicis, 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. 
 
 EXTENSOR This small muscle arises from the posterior 
 
 PBIMI INTERNODII surface of the radius, below the preceding, and 
 POLLICIS. from the interosseous membrane. It descends 
 
 obliquely in company with the preceding muscle, turns over the 
 radial extensors of the wrist, and terminates upon a tendon which 
 passes beneath the annular ligament, through the groove on the 
 
332 DISSECTION OF THE BACK OP THE FOREAKM. 
 
 outer part of the radius, and is inserted into the radial side of the 
 base of the first phalanx of the thumb. 
 
 EXTENSOR This muscle arises from the posterior surface 
 
 SECUNDI INTER- of the ulna, below the last muscle, and from the 
 NODII POLLICIS. interosseons membrane. The tendon receives 
 fleshy fibres as low as the wrist, passes beneath the annular liga- 
 ment, 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 in- 
 serted 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 muscle arises from the posterior surface 
 
 INDICTS OR INDI- of the ulna, below the extensor secundi inter- 
 CATOR. nodii pollicis. 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 the hand to the first phalanx of 
 the index finger, where it is united to the inner border of the com- 
 mon extensor tendon. By the action of this muscle the index 
 finger can be extended independently of the others. 
 
 Eeflect the extensor carpi radialis brevior and 
 the anconeus from their origins, to expose the fol- 
 lowing muscle. 
 
 SUPINATOR This muscle embraces the upper third of the 
 
 RADII BRBVIS. radius. It arises from the external lateral liga- 
 ment 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 
 
DISSECTION OF THE BACK OP THE FOEEAEM. 333 
 
 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 traversed 
 obliquely by the posterior interosseous nerve, which sends a branch 
 to it, 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. 
 
 POSTERIOE This artery comes from the ulnar by a common 
 
 INTEROSSEOUS trunk with the anterior interosseous (p. 296), and 
 
 ARTERY. supplies the muscles on the back of the forearm. 
 
 It passes between the oblique ligament and the interosseous mem- 
 brane, and appears, at the back, 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. 
 
 The largest branch of this artery is the interosseous recurrent. It 
 ascends beneath the anconeus 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, and with the 
 posterior ulnar recurrent artery. 
 
 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. 
 
 POSTERIOR The nerve which supplies the muscles on the 
 
 INTEROSSEOUS back of the forearm, is the posterior interosseous, 
 
 NERVE, one of the divisions of the musculo-spiral. 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 
 
334 
 
 DISSECTION OF THE BACK OF THE FOREARM. 
 
 the extensor 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 
 
 FIG. 61. 
 
 1. The superior profunda. 
 
 2. The anastomotica magna. 
 
 3. The posterior ulnar recur- 
 
 rent. 
 
 4. The posterior ) 5^ ascending 
 
 interosseous f^d descend- 
 I ing branches. 
 
 5. The termination of the an- 
 
 terior interosseons. 
 
 6. The posterior carpal arch. 
 
 DIAGRAM SHOWING THE ANASTOMOSES OF ARTERIES AT THE BACK OF THE ELBOW 
 AND WRIST JOINTS. 
 
 the common extensor tendons the nerve forms a gangliform enlarge- 
 ment from which filaments are sent to the carpal and metacarpal 
 joints. 
 
 DISSECTION. ^ ie ra dial artery is continued over the external 
 
 RADIAL ARTERY lateral ligament of the carpus, beneath the extensor 
 
 ON THE BACK OF tendons of the thumb, to the proximal part of the 
 
 interval between the first and second metacarpal 
 
DISSECTION OF THE BACK OF THE FOEEAEM. 335 
 
 bones, where it dips down 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 termina- 
 tion of the anterior interosseous artery, and forms an arch beneath the 
 extensor tendons, with a corresponding branch from the ulnar artery. 
 The carpal artery sends off small branches, called the dorsalinterosseous, 
 which descend along the third and fourth interosseous spaces from the 
 arch just mentioned, beneath the extensor tendons, and inosculate near 
 the carpal ends of the metacarpal bones with the perforating branches 
 from the deep palmar arch. 
 
 b. The first dorsal interosseous artery is generally larger than the 
 others. It passes towards the second interosseous space to the cleft be- 
 tween the index and middle fingers, communicating here with a perfora- 
 ting 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 metacarpal 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. 
 
 Remove the tendons from the back, and from 
 
 the palm, 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 continuous inferiorly with the 
 
336 
 
 INTEKOSSEOUS MUSCLES. 
 
 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 metacarpal bones. 
 
 TRANSVERSE This consists of strong bands of ligamentous 
 
 METACARPAL fibres, which pass transversely between the distal 
 
 LIGAMENT. extremities of the metacarpal bones. These bands 
 
 are intimately united to the fibre-cartilaginous ligament of the 
 metacarpal joints, and are of sufficient length to admit of a certain 
 degree of movement' between the ends of the metacarpal bones. 
 
 FIG. 62. 
 
 FIG, 63. 
 
 DIAGRAM OF THE FOUR DORSAL IN- 
 TEROSSEI, DRAWING FROM THE 
 MIDDLE LINE. 
 
 DIAGRAM OF THE THREE PALMAR 1NTEB- 
 OSSEI. AND THE ADDUCTOR POLLICIS, 
 DRAWING? TOWARDS THE MIDDLE LINE. 
 
 DISSECTION. 
 
 Remove the fascia which covers the interosseous 
 muscles, and separate the metacarpal bones by 
 dividing the transverse metacarpal ligament. A bursa is fre- 
 quently developed between their digital extremities. 
 
 INTEROSSEOUS These muscle&, so named from their position, 
 
 MUSCLES. 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 muscles, one of which 
 
INTEROSSEOUS MUSCLES. 337 
 
 is an abductor, the other an adductor, of a finger. Thus 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.* They are all supplied by the ulnar nerve. 
 
 DOKSAL Each dorsal interosseous muscle arises from the 
 
 INTEBOSSEI. opposite sides of two contiguous metacarpal bones 
 
 (fig. 62). From this double origin the fibres converge to a ten- 
 don, which passes between the metacarpal joints of the finger, and 
 is inserted into the side of the base of the first phalanx, and by a 
 broad expansion into the extensor tendon on the back of the same 
 finger. 
 
 The first dorsal interosseous muscle (abductor indicia] is larger 
 than the others, and occupies the interval between the thumb and 
 fore-finger. It arises from the proximal 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 
 metacarpal 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 a line be drawn longitudinally through the middle finger, 
 as represented by the dotted line in fig. 62, we find that all the 
 dorsal interosseous muscles are abductors from that line; conse- 
 quently, they separate the fingers from each other. 
 
 PALMAR INTER- It requires a careful examination to distinguish 
 OSSEOUS. this set 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 
 
 * If we consider the adductor pollicis as a palmar interosseous muscle, there would 
 be four palmar and four dorsal all supplied by the ulnar nerve. 
 
 Z 
 
338 STEKSO-CLAVICULAR JOINT. 
 
 the muscle is inserted (fig. 63). They terminate in small tendons, 
 which pass between the metacarpal joints of the fingers, and are 
 inserted, like those of 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 a line 
 drawn through the middle finger (fig. 63). They are, therefore, 
 the opponents of the dorsal interosseous, and move the fingers 
 towards each other. 
 
 The palmar and dorsal interossei are supplied by filaments 
 from the deep branch of the ulnar nerve. 
 
 DISSECTION OF THE LIGAMENTS. 
 
 STBKNO-CLAVI- The i nner en( l of the clavicle articulates with 
 
 CULAK JOINT. the comparatively small and shallow excavation 
 
 on the upper and outer part of the sternum. The security of the 
 joint depends upon the great strength of its ligaments. There are 
 two synovial membranes, and an intervening fibro-cartilage. 
 
 The anterior sterno-clavicular ligament (fig. 64) consists of a 
 strong broad band of ligamentous fibres, which pass obliquely 
 downwards and inwards over the front of the joint, from the inner 
 end of the clavicle to the anterior surface of the sternum. 
 
 The posterior sterno-clavicular ligament extends over the 
 back of the joint, from the back of the clavicle to the back of the 
 sternum in a similar manner to the anterior. 
 
 The inter-clavicular ligament connects the clavicles directly. 
 It extends transversely above the notch of the sternum, and has a 
 broad attachment to the upper border of each clavicle. Between 
 
STERNO-CLAV1CULAR JOINT. 
 
 339 
 
 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 for the joint a complete fibrous 
 capsule of such strength that dislocation of it is rare. 
 
 The costo-clavicular or rhomboid ligament connects the cla- 
 vicle to the cartilage of the first rib. It ascends obliquely out- 
 wards and backwards from the cartilage of the rib to a rough sur- 
 face 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. 
 
 FIG. 64. 
 
 DIAGRAM OF THE STJ3JJNO-CLAYICTLAB LIGAMENTS. 
 
 1. Inter-clavicular ligament. 
 
 2. Anterior sterno-clavicular ligament. 
 
 3. Costo-clavicular ligament. 
 
 4. Inter-articular fibro-cartilage. 
 
 Inter-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 anterior and posterior ligaments. 
 
 The joint is provided with two synovial membranes : one 
 between the articular surface of the sternum and the inner surface 
 
 z 2 
 
340 SCAPULO-CLAVICULAE JOINT, 
 
 of the fibro-cartilage ; the other between the articular surface of 
 the clavicle and the outer surface of the fibro-cartilage. 
 
 This inter-articular fibro-cartilage is a structure highly elastic, 
 without admitting of any stretching. It equalises pressure, breaks 
 shocks, and also acts as a ligament, tending to prevent 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 be moved upon the sternum in a 
 direction either vertical or horizontal : thus it admits of circum- 
 duction. These movements, though limited at the sternum, are 
 considerable at the apex of the shoulder. 
 
 SCAPULO- The outer end of the clavicle articulates with 
 
 CLAVICULAR the acromion, and is connected by strong liga- 
 
 JomT - ments to the coracoid process of the scapula. 
 
 The clavicle and the acromion articulate with each other by 
 two flat oval cartilaginous surfaces, of which the planes slant in- 
 wards, and the longer diameters are in the antero-posterior 
 direction. 
 
 The superior ligament, a broad band of ligamentous fibres, 
 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 inter-articular fibro-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, 
 should be considered as one. The trapezoid ligament is the more 
 
SHOULDER JOINT. 
 
 341 
 
 anterior and external. It arises from the back part of the coracoid 
 process, and ascends obliquely backwards and outwards to the 
 clavicle, near its outer end. The conoid ligament is fixed at its 
 apex to the root of the coracoid process, ascends nearly vertically, 
 and is attached by its base to the clavicle. When the clavicle is 
 fractured in the line of the attachment of the coraco-clavicular 
 ligament, there is little or no displacement of the fractured ends, 
 these being kept in place by the ligament. 
 
 LIGAMENTS OF These are two : the transverse ligament, at- 
 
 THE SCAPULA. tached to the margins of the supra-scapular notch ; 
 
 and the coraco-acromial or triangular ligament, attached by its 
 
 \ portions of 
 
 1. Trapezoid [the coraco- 
 
 2. Conoid | clavicular 
 
 ' ligament. 
 
 3. Supra-scapular or trans- 
 
 verse ligament. 
 
 4. Coraco-acromial liga- 
 
 meiit. 
 
 - 5. Tendon of biceps. 
 
 6. Capsular ligament of 
 
 the shoulder-joint. 
 ' 7. Coraco-humeral liga- 
 ment. 
 
 8. Foramen in the cap- 
 sulnr ligament for the 
 subscapularis tendon. 
 
 ANTERIOR TIEW OF THE SCAPULO-CLAVICULAR LIGAMENTS, AND OF THB 
 SHOULDER-JOINT. 
 
 apex to the acromion, and by its base to the outer border of the 
 coracoid process. It is separated from the upper part of the 
 capsule of the shoulder-joint by a large bursa. 
 
 SHOULDER- The articular surface of the head of the humerus, 
 
 JOINT - forming 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 and are in 
 timately connected with it. 
 
342 SHOULDER JOINT. 
 
 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 j oint ; 
 also in cases of paralysis of the deltoid. 
 
 The capsular ligament is attached above, round the circum- 
 ference of the glenoid cavity ; below, round the anatomical neck 
 of the humerus. It is strongest on its upper aspect, weakest and 
 longest on its lower. It is strengthened on its upper and pos- 
 terior part by the tendons of the supra-spinatus, infra-spinatus, 
 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. t 
 
 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 is first protruded in dis- 
 locations into the axilla. 
 
 At the upper and inner side of the joint, a small opening 
 (foramen ovale) is observable in the capsular ligament, through 
 which the tendon of the subscapularis passes, and comes in contact 
 with the synovial membrane. 
 
 The upper surface of the capsule is strengthened by a strong 
 band of ligamentous fibres, called the coraco-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 
 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 
 tuberosities, becomes slightly flattened, and passes over the head 
 
ELBOW JOINT. 343 
 
 of the hone to be attached to the upper border of the glenoid 
 cavity. It is loose and movable within the joint. It acts like a 
 strap, keeping down the head of the bone when the arm is raised 
 by the deltoid. 
 
 The tendon of the biceps, strictly speaking, does not perforate 
 the synovial membrane 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 fibrous 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 what mechanics call a universal 
 joint. It is capable of motion forwards and backwards, of adduc- 
 tion, abduction, circumduction, and rotation. 
 
 The elbow-ioint is a perfect hinge. The larger 
 ELBOW-JOINT. 
 
 sigmoid cavity of the ulna is adapted to the 
 
 trochlea upon the lower end of the humerus, admitting only of 
 flexion and extension ; while the shallow excavation upon the head 
 of the radius admits not only of flexion and extension, but of rota- 
 tion, upon the rounded articular eminence (capitellum) of the 
 
344 
 
 ELBOW JOINT. 
 
 humerus. 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. The head is simply sur- 
 rounded by a ligamentous collar, called the annular ligament, 
 within which it freely rolls in pronation and supination of the 
 hand. 
 
 Internal lateral ligament. This is triangular, and is divided 
 into two portions, an anterior and a posterior. Its anterior part 
 is attached to the front of the internal condyle of the humerus : 
 
 FIG. 66. 
 
 a. External lateral liga- 
 ment. 
 
 6. Orbicular or annular 
 ligament. 
 
 c. Part of internal la- 
 
 teral ligament. 
 
 d. Radius, removed from 
 
 the annular liga- 
 ment. 
 
 LIGAMENTS OF THE ELBOW JOINT. 
 
 from this point the fibres radiate, and are inserted along the inner 
 margin of the coronoid process of the ulna. The posterior part is 
 also triangular, and passes from the back part of the internal con- 
 dyle to the inner border of the olecranon. 
 
 A band of fibres extends transversely from the olecranon to 
 the coronoid process, across a notch observable on the inner side 
 of the sigmoid cavity : through this notch small vessels pass into 
 the joint. 
 
 External lateral ligament. This is attached to the external 
 condyle of the humerus, and is in intimate connection with the 
 
RADIO-ULNAE, JOINT. 345 
 
 common tendon of the extensors. The fibres spread out as they 
 descend, and are interwoven with the annular ligament, surround- 
 ing the head of the radius. 
 
 The anterior and posterior ligaments of the elbow-joint con- 
 sist 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 : the coronoid process 
 limits the one ; the olecranon the other. 
 
 The preceding ligaments, collectively, form a continuous cap- 
 sule for the joint. 
 
 SUPERIOR The orbicular or annular ligament of the 
 
 EADIO-ULNAR radius (fig. 66) does not of itself make a ring. 
 
 ABTICULATION. j^g en( j g are attached to the anterior and posterior 
 borders 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 ring is narrower 
 than the upper, the better to clasp the neck of the radius, and 
 maintain it more accurately in position. The external lateral 
 ligament is attached to its outer surface. 
 
 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 annular ligament. It is widest and 
 loosest under the tendon of the triceps. Where the membrane is 
 reflected from the bones upon the ligaments, there is more or less 
 adipose tissue, particularly in the fossse on the front and back part 
 of the lower end of the humerus. 
 
 INTEROSSEOUS This is an aponeurotic septum, stretched be- 
 
 LIGAMBNT OR tween the bones of the forearm, of which the chief 
 
 MEMBRANE. purpose is to afford an increase of 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 
 
346 RADIO-CARPAL JOINT. 
 
 band of 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 
 and the upper border of the interosseous membrane is a triangular 
 interval through which the posterior interosseous artery passes to 
 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. 
 
 BADIO-CARPAL This joint is formed by the lower end of the 
 
 OR WRIST-JOINT. radius, which articulates with the scaphoid and 
 semilunar bones of the carpus : the lower end of the ulna is ex- 
 cluded from the joint by a triangular fibro- cartilage, which articu- 
 lates with a small portion of the cuneiform bone. The joint is 
 secured by an anterior, a posterior, and two lateral ligaments. 
 
 The external lateral ligament extends from the styloid process 
 of the radius to the scaphoid bone, to the anterior annular ligament, 
 and to the trapezium. 
 
 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 annular 
 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 surface of the trian- 
 gular 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. 
 
 INFERIOR ^ e i nner surface of the lower end of the radius 
 
 BADIO-TILNAR presents a slight concavity, which rotates upon 
 
 ABTICUI.ATION. the convex head of the ulna : this mechanism is 
 
RADIO-CARPAL JOINT. 
 
 347 
 
 essential to the pronation and supination of the hand. These 
 corresponding surfaces are covered with a thin layer of cartilage, 
 and are provided with a very loose synovial membrane. The joint 
 is strengthened in front and behind by thin transverse ligamentous 
 fibres, which extend 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 me- 
 dium between the bones is the following strong fibro-cartilage : 
 
 Fia. 67. 
 
 1. External lateral liga- 
 
 ment 
 
 2. Internal lateral liga- 
 
 ment. 
 
 3. Interarticular fibro- 
 
 cartilage between 
 radius and ulna. 
 
 4. Interosseous liga- 
 
 ments. 
 
 5. Lateral ligaments 
 
 of the intercar- 
 pal joint. 
 
 DIAGRAM OF THE LIGAMENTS AND SYNOVIAL MEMBRANES OF THE WRIST- JOINT. 
 
 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- 
 tained of the fibro-cartilage which connects them (fig. 67). 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 ; its apex to 
 
348 CARPAL JOINTS. 
 
 a depression at the root of the styloid process of the ulna. It is 
 thin at the base and centre, thicker at the apex and sides. Its 
 upper surface is in contact with the ulna, and covered by the 
 synovial membrane of the radio-ulnar joint ; its lower surface, 
 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 an abnormal projection 
 of the lower end of the ulna. 
 
 The synovial membrane of this joint is distinct from that of 
 the wrist, except in the case of a perforation through the fibro- 
 cartilage. On account of its great looseness, necessary for the free 
 rotation of the radius, it is called membrana sacciformis. 
 
 The bones of the carpus are arranged in two 
 CARPAL JOINTS. j i j , j j. -L J.T- 
 
 rows, an upper and a lower, adapted to each other, 
 
 so as to form between them a joint, connected by anterior, posterior, 
 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 con- 
 tiguous surfaces (those of the pisiform and cuneiform excepted) 
 are covered by the reflections of one synovial membrane. 
 
 The first row is united by dorsal and palmar transverse liga- 
 ments proceeding from the scaphoid to the semilunar bone, and 
 from the semilunar to the cuneiform ; also by interosseous liga- 
 ments, proceeding from the semilunar to the bones on either side 
 of it (fig, 67). 
 
 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 second row of carpal bones is connected in the same way 
 as the upper. The dorsal and palmar ligaments pass transversely 
 
CAEPAL JOINTS. 349 
 
 from one to the other. There are usually two interosseous liga- 
 ments, one on either side of the os magnum ; sometimes there is a 
 third, between the trapezium and trapezoid bones ; they are thicker 
 and stronger than those of the upper row, and unite the bones 
 more firmly together. 
 
 INTEBCABPAL The upper row of carpal bones is arranged in the 
 
 JOINT. form of an arch, so as to receive the corresponding 
 
 convex surfaces of the os magnum and unciforme. External to 
 the os magnum, the trapezium and trapezoid bones present a 
 slightly concave surface, which articulates with the scaphoid. In 
 this way a joint admitting 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 ligaments consist of strong ligamentous fibres, 
 which pass obliquely from the bones of the upper to those of the 
 lower row. The posterior ligaments consist of oblique and trans- 
 verse 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 imciform bones. 
 
 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. 
 
 JOINT BETWEEN ^ ne trapezium presents a cartilaginous surface, 
 TBAPEZIUM AND convex in the transverse, and concave in the antero- 
 THE FIEST META- posterior direction (i.e. saddle-shaped), which arti- 
 NE< culates with the cartilaginous surface on the meta- 
 
 carpal 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, which is one 
 
CARPO-METACAEPAL JOINTS. 
 
 of the great characteristics of the human hand. The joint is sur- 
 rounded 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. 
 
 The metacarpal bones of the fingers are con- 
 
 CABPAL JOINTS nected to the second row of the carpal bones by 
 
 ligaments upon their palmar and dorsal surfaces. 
 
 The dorsal ligaments are" the stronger. The metacarpal bone 
 of the fore-finger has two : one from the trapezium, the other 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 
 trapezium, 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 consider- 
 able 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. 67). 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. 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 
 
JOINTS OF THE FINGERS. 351 
 
 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 
 by interosseous ligaments, which extend between the bones, 
 immediately below their contiguous cartilaginous surfaces. 
 
 The distal extremities of these bones are loosely connected on 
 their palmar aspect by the transverse metacarpal ligament. 
 
 SYNOVIAL MEM- There are six distinct synovial membranes, 
 BRANES OF THE proper to the lower end of the radius, and the 
 several bones of the carpus (see the diagram, p. 
 347) as follows : 
 
 a. One between the lower end of the radius and the ulna. 
 
 b. 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. 
 
 FIRST JOINT OF The first phalanx of the finger presents a shal- 
 THE FINGERS. low oval cavity, crusted with cartilage, with the 
 
 broad 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 ligaments, and 
 a palmar. 
 
 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. 
 
352 JOINTS OP THE FINGERS. 
 
 The palmar ligament is a thick, compact, fibrous struc- 
 ture, 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 either side it is in- 
 separably 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, for the play of the flexor 
 tendons ; its deep surface is adapted to cover the head of the meta- 
 carpal bone. Two sesamoid bones are found in the palmar liga- 
 ment belonging to the joint between the metacarpal bone and the 
 first phalanx of the thumb. 
 
 The palmar 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 may require much manipulation. 
 
 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. 
 
 SECOND AND The corresponding articular surfaces of the 
 
 LAST JOINT OF phalanges of the fingers and thumb are so shaped 
 THE FINGERS. as ^ o form a hinge-joint, and, therefore, in- 
 
 capable of lateral movement. The ligaments connecting them 
 are similar in every respect to those between the metacarpal bones 
 and the first phalanges. The palmar ligament of the last joint of 
 the thumb generally contains a sesamoid bone. 
 
353 
 
 DISSECTION OF THE ABDOMEN. 
 
 ARBITRARY 
 DIVISION INTO 
 REGIONS. 
 
 These lines form 
 FIG. 68. 
 
 The abdomen is divided into arbitrary regions, 
 that the situation of the viscera contained in it 
 may be more easily described. For this purpose 
 we draw the following lines : one horizontally across the abdomen 
 on a level with the cartilages of the ninth ribs ; another on a level 
 with the anterior superior spines of the ilia, 
 the boundaries of three spaces, each 
 of which is subdivided into three 
 regions by a vertical line drawn on 
 each side from the cartilage of the 
 eighth rib to the middle of Poupart's 
 ligament. Thus, there are a central 
 and two lateral regions in each space. 
 The central region of the upper space 
 is termed the epigastric ; 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 hypo- 
 chondriac, 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 
 blowpipe inserted into the abdominal cavity at the umbilicus. 
 
 _. An incision should be made from the sternum 
 
 DISSECTION. . 
 
 to the pubes, another from the anterior spine of the 
 
 A A 
 
354 
 
 SUPEEFICIAL VESSELS OF THE GEOIN. 
 
 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 angles of the ribs. The skin should then 
 be dissected from the subjacent adipose and connective tissue, 
 called the superficial fascia. 
 
 FIG. 69. 
 
 SUPERFICIAL VESSELS AND GLANDS OF THE GHOIN. 
 
 1. Saphenous opening of the fascia lata. 
 
 2. Saphena vein. 
 
 3. Superficial epigastric a. 
 
 4. Superficial circmnflexa ilii a. 
 
 5. Superficial pudic a. 
 
 6. External abdominal ring. 
 
 7. Fascia lata of the thigh. 
 
 SUPERFICIAL 
 FASCIA. 
 
 The subcutaneous tissue of the abdomen has 
 the same general characters as that of other 
 parts, and varies in thickness in different persons, according to 
 the amount of fat. At the lower part of the abdomen, it admits of 
 separation into two layers, between which are found the sub- 
 
SUPERFICIAL VESSELS OP THE GROIN. 355 
 
 cutaneous blood-vessels, the lymphatic glands, the ilio-inguinal 
 nerve, and the hypogastric branch of the ilio-hypogastric nerve. 
 
 Eespecting 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, extravasated 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. 
 
 Between the layers of the superficial fascia on 
 
 SUPERFICIAL . * r 
 
 BLOOD-VESSELS the groin and upper part of the thigh, are several 
 AND LYMPHATIC lymphatic glands and small blood-vessels (fig. 69). 
 GLANDS. ij^g gj an( jg are named, according to their situation, 
 
 inguinal or 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. 69). They receive the super- 
 ficial lymphatics from the lower part of the wall of the abdomen, 
 from the scrotum, penis, perineum, anus, and gluteal region, and 
 are therefore generally affected in venereal disease. The lymph- 
 atics 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 superficial epigastric, ascends over Poupart's 
 ligament and ramifies over the lower part of the abdomen, as high 
 as the umbilicus, inosculating with the deep epigastric artery ; 
 another, the superficial external pudic, crosses the spermatic 
 cord, and is distributed to the skin of the penis and scrotum ; a 
 third, the superficial circumflexa ilii, ramifies towards the spine 
 of the ilium. These subcutaneous arteries, the pudic especially, 
 often occasion a free hemorrhage in the operation for strangulated 
 hernia. 
 
 A A 2 
 
356 ABDOMINAL MUSCLES. 
 
 The corresponding veins join the saphena vein of the thigh. 
 Under ordinary circumstances they do not appear in the living 
 subject ; 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.* 
 
 CUTANEOUS The skin of the abdomen is supplied with nerves 
 
 NERVES. after the same plan as the chest : namely, by 
 
 lateral and anterior branches derived from the five or six lower 
 intercostal nerves, as follows : 
 
 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. The lateral branch of the twelfth 
 dorsal nerve is larger than the others, and passes over the crest 
 of the ilium to the skin of the buttock, without dividing like 
 the other nerves. 'The corresponding branch of the first lumbar 
 has a similar distribution. 
 
 6. The anterior cutaneous nerves emerge 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 in the 
 female. 
 
 A small nerve namely; the genital branch of the genito-crural 
 comes through the external ring. <Jt lies behind the cord close 
 to the outer pillar. 
 
 DISSECTION. The deep layer of the superficial fascia should 
 
 now be removed from the external oblique, by commencing at the 
 
 * A cast in illustration of this is preserved in the Museum of St. Bartholomew's 
 Hospital. 
 
ABDOMINAL MUSCLES. 357 
 
 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 latissimus dorsi must also be made outt 
 
 MUSCLES OF THE The abdominal muscles, three on each side, 
 ABDOMINAL are arranged in strata, named, after the direction 
 
 of their fibres, the external 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 rectus, which extends perpendicularly on each side the 
 linea alba from the sternum to the pubes. 
 
 EXTEENAL OB- This muscle arises from the eight or nine lower 
 UQUE. ribs, by as many pointed bundles, called digita- 
 
 tions. The upper five of these interdigitate with similar bundles 
 of the serratus magnus ; the three lower correspond in like manner 
 with the origin of the latissimus dorsi ; but they cannot be seen 
 unless the body be turned on the side. The upper part of this 
 muscle descends obliquely forwards, and terminates in the apo- 
 neurosis of the abdomen ; the lower proceeds almost perpendicu- 
 larly from the last ribs, and is inserted into the outer lip of 
 more than the anterior half 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 by their 
 decussation in the middle line the linea alba, which extends from 
 the ensiform cartilage to the pubes. 
 
 POTJPART'S Along the line of junction of the abdomen 
 
 LIGAMENT OK with, the thigh, the aponeurosis extends from the 
 
 CRTTRAL ARCH. . . ,. ,, .-., ,, 
 
 anterior superior spine ot the ilium to the spine 
 
 of the pubes, and forms an arch over the intermediate bony exca-. 
 vation (p. 358). This, which is termed the crural arch, or more 
 
 * From its position and the direction of its fibres, it is manifest that the ex- 
 ternal oblique represents, in the abdomen, the. external intercostal muscles of. the, 
 chest. 
 
358 
 
 ABDOMINAL MUSCLES. 
 
 commonly Poupart's ligament,* transmits the great vessels of 
 the thigh, with muscles and nerves. 
 
 This ligament, when not separated from its fascial connections, 
 does not run straight from the spine of the ilium to that of 
 the pubes, but is slightly curved, with its convexity towards the 
 thigh. Above, and somewhat to the outer side of the spine 
 of the pubes, is situated an opening in the aponeurosis, called 
 
 Fio. 70. 
 
 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. 
 
 DIA3RAM OF POUPART S LIGAMENT, OF THE APONEUBOSIS OF THE EXT EKNAL OBLIQUE, 
 AND OF THE EXTERNAL ABDOMINAL EING. 
 
 the external abdominal ring. In the male it is a triangular 
 opening about an inch long, with its base at the pubes, and will 
 admit the passage of a finger ; it transmits the spermatic cord. 
 In the female it is smaller and transmits the round ligament of 
 the uterus. It is bounded by the free margins of the aponeurosis 
 
 * This was first described by Fallopius, an Italian anatomist, in his ' Observa- 
 tiones Anatomicse,' published in 1561. It was subsequently described by Poupart 
 in 1705, in the 'M6m. de 1'Acad. de Paris,' and is now commonly called 'Poupart's 
 ligament.' 
 
ABDOMINAL MUSCLES. 859 
 
 which are termed its columns or pillars. The inner pillar (No. 4 
 in the diagram) is thin, and is attached to the front of the pubes, 
 decussating with its fellow of the opposite side in front of the 
 symphysis. The outer pillar is thicker and stronger, and has three 
 attachments ; one, into the spine of the pubes Poupart's ligament 
 (No. 3) ; another, for nearly an inch along the linea ilio-pectinea 
 Gimbernafs ligament (No. 2); the third or triangular ligament 
 consists of a few fibres which pass .obliquely 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 some 
 arched fibres called intercolumnar bands, which are strongest above 
 the external ring. Their use is to strengthen the opening and 
 prevent the ring from enlarging. 
 
 Attached to the pillars of the external ring is a thin fascia, 
 the intercolumnar or spermatic fascia, which is prolonged over 
 the spermatic cord and testis, and thus forms one of the coverings 
 of that organ. 
 
 The spermatic cord in its passage through the ring rests upon 
 the external pillar. 
 
 The external oblique should now be detached 
 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 direc- 
 tion of its fibres, which run upwards and inwards. 
 
 INTERNAL This muscle arises by fleshy fibres from the 
 
 OBLIQUE. outer half of Poupart's ligament, from the anterior 
 
 two-thirds of the middle lip of the crest of the ilium, and from 
 the fascia lumborum.* The fibres ascend obliquely and are 
 inserted as follows : the posterior, into the cartilages of the three 
 or four lower ribs ; the middle, into the abdominal aponeurosis ; 
 and the anterior (which arise from Poupart's ligament) arch in- 
 wards over the spermatic cord, and descend somewhat to be in- 
 
 * The internal oblique represents, in the abdomen, the internal intercostal muscles 
 of the thorax. 
 
360 
 
 ABDOMINAL MUSCLES. 
 
 serted, in common with the tendon of the transversalis muscle 
 into the pubes and for a short distance into the linea ilio-pectinea, 
 immediately behind the external ring. 
 
 The aponeurosis of the internal oblique is the broad expanded 
 tendinous tissue into which the muscle is anteriorly attached. It 
 extends from the chest to the pelvis, and its fibres run in the same 
 direction as the muscle. At the outer border of the rectus it splits 
 into two layers : an anterior, which passes in front of the rectus 
 in conjunction with the aponeurosis of the external oblique ; and 
 
 FIG. 71. 
 
 1. Conjoined tendon of 
 internal oblique and 
 transversalis. 
 
 2. Cremaster muscle 
 passing down in 
 loops orer the 
 cord. 
 
 DIAGRAM OF THE LOWER FIBRES OF THE INTERNAL OBLIQUE AND TRANSVERSALIS, 
 WITH THE CREMASTER MUSCLE. 
 
 a posterior, which, in common with the aponeurosis of the 
 transversalis, passes behind the rectus. The two layers thus 
 form a sheath for the rectus, which, except at the lower fourth 
 behind, is complete. Midway between the umbilicus and the pubes, 
 the aponeuroses of all the three muscles pass in front of the rectus, 
 so that posteriorly in this situation it has no sheath. The lower 
 free border of the posterior part of the sheath* marks the situation 
 where the deep epigastric artery enters the substance of the rectus. 
 * Sometimes called the ' semilunar fold of Douglas.' 
 
ABDOMINAL MUSCLES. 361 
 
 CREMASTER The cremaster is a thin pale muscle, or the 
 
 MUSCLE. reverse, according to the condition of the subject. 
 
 It is best to regard it as a detachment of the lowest fibres of 
 the internal oblique, which, proceeding from Poupart's ligament, 
 descend in front of the spermatic cord, and then arch up again 
 to the spine and crest of the pubes, forming loops of different 
 lengths ; some reaching only as low as the external ring, others 
 lower still, whilst the lowest spread out over the tunica vaginalis 
 of the testis. The muscular fibres are frayed out, being connected 
 by loose cellular tissue, and form a covering for the testis, called 
 the cremasteric fascia. This muscle is absent in the female. Its 
 nerve comes from the genital branch of the genito-crural, and its 
 artery (cremasteric) from the deep epigastric. 
 
 The internal oblique should now be detached 
 DISSECTION. n 
 
 from the ribs and the crest of the ilium, and turned 
 forwards, without disturbing that portion of it connected with the 
 crural arch. To avoid cutting away any part of the transversalis 
 in reflecting the internal oblique, dissect near the crest of the ilium, 
 and search for an artery which runs between these muscles and 
 may be followed as a guide. This artery, called the deep circum- 
 ftexa ilii, is a branch of the external iliac, and supplies the abdo- 
 minal muscles. Beneath the internal oblique the continuations of 
 the intercostal nerves and vessels are brought into view. These 
 should be preserved. 
 
 TRANSVERSALIS This muscle arises from the outer third of 
 ABDOMINIS. Poupart's ligament, from the anterior two-thirds 
 
 of the crest of the ilium, from a strong 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 digita- 
 tions which correspond with those of the diaphragm. From this 
 origin the fibres pass horizontally forwards and terminate an- 
 teriorly in a broad aponeurosis. Some of its fibres arch down- 
 wards, and are inserted with some fibres of the internal oblique by 
 means of a conjoined tendon into the pubes. 
 
 The aponeurosis into which the fibres are inserted is broader 
 below than above, and forms part of the posterior sheath of the 
 rectus, excepting in the lower fourth, where it passes entirely in front. 
 
362 
 
 ABDOMINAL MUSCLES. 
 
 KECTUS This long muscle is situated vertically in front 
 
 ABDOMINIS. o f ^ e abdomen, and is enclosed in a sheath formed 
 
 by the aponeuroses of the lateral muscles of the abdomen. To 
 expose it, therefore, slit up the middle of the sheath, and reflect 
 the two halves. It arises by two tendons, the inner and smaller 
 of which is attached to the symphysis, the outer to the crest of 
 the pubes. As the fibres pass up, the muscle becomes broader and 
 thinner, and is inserted into the fifth, sixth, and seventh costal 
 cartilao'es. Notice the tendinous intersections across the muscle 
 
 O 
 
 called linece transversce, which are 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 
 FlG 72. sheath in front, but not 
 
 behind ; consequently, 
 pus formed between the 
 front of the rectus and 
 its sheath would be con- 
 fined by two intersec- 
 tions; not so on the 
 back of the muscle, 
 where pus might travel 
 down the entire length 
 of it. 
 
 The sheath of the 
 rectus consists in front 
 of the aponeurosis of 
 the external oblique, 
 
 ERECTOR SP. 
 
 TRANSVERSE SECTION THEOUGH THE ABDOMINAL MUS- 
 CLES TO SHOW THE FORMATION OF THE SHEATH OF 
 THE RECTUS, THE QUADBATUS LUMBOHUM AXU THE and half the 
 ERECTOR 
 
 oblique ; while the back of the sheath comprises the aponeurosis 
 of the transversalis, and half that of the internal oblique (fig, 71). 
 This, however, applies only to the upper three-fourths of the 
 muscle ; the lower fourth has no sheath behind, since all the 
 aponeuroses pass in front of it. 
 
 * Some animals e.g. the crocodile have bony abdominal ribs. 
 
ABDOMINAL MUSCLES. 363 
 
 p^ 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 mid- 
 way between the pubes and the umbilicus. It is often absent on 
 one or even both sides. 
 
 Linea alba. The aponeuroses of the abdominal muscles decus- 
 sate along the middle line and form a white fibrous band, extending 
 from the ensiform cartilage to the pubes. This is the linea alba: 
 it is the fibrous continuation of the sternum and is broader above 
 than below. A little lower than the middle is the umbilicus. 
 
 The linea alba, being the thinnest part of the abdomen, and 
 free from large blood-vessels, is chosen as a safe line for tapping in 
 dropsy, for puncturing the bladder in retention of urine, and for 
 ovariotomy. 
 
 Linece semilunares. These are the two slightly curved lines, 
 on the front of the abdomen, corresponding with the outer margins 
 of the two recti muscles. They are formed by the junction of the 
 aponeuroses of the lateral muscles." 
 
 The abdominal muscles serve many important purposes : 
 FUNCTIONS OF l^- ^ n tranquil expiration they push the dia- 
 
 THE ABDOMINAL phragm upwards by gentle pressure on the abdo- 
 minal viscera. 
 
 In forcible expiration the same process takes place, but with 
 greater energy. This is variously exemplified in coughing, 
 sneezing, and laughing. 
 
 2nd. In vomiting, the diaphragm being fixed* by the closure 
 of the glottis, the abdominal muscles contract, and assist the sto- 
 mach to expel its contents. 
 
 3rd. In conjunction with the contracted diaphragm, they 
 assist the muscular walls of the bladder and rectum in the expul- 
 sion of urine and faeces, and the action of the uterus in partu- 
 rition. They exercise a gentle pressure and support on the 
 abdominal viscera, and shield them from injury by strongly con- 
 tracting when a blow is anticipated. 
 
 * By the term ' fixed,' it is meant that the diaphragm forms a resisting surface. 
 
364 PAETS CONCEENED IN INGUINAL HEENIA. 
 
 4th. They are movers of the trunk in various ways. For 
 example, the right external oblique acting with the left internal 
 oblique will rotate the chest towards the left side, as in mowing, 
 and vice versa. 
 
 The rectus is chiefly concerned in raising the body from the 
 horizontal position, as anyone may ascertain by placing his hand 
 on the abdomen while rising from the ground. 
 
 By dividing the rectus transversely near the 
 DISSECTION. . 
 
 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 absent behind the lower fourth 
 of the muscle. Eamifying in the substance of the muscle is a 
 large artery, called the deep epigastric, a branch of the external 
 iliac ; also the continuation of the internal mammary, which de- 
 scends from the subclavian. 
 
 NEBVES OF THE These nerves are the continuations of the six lower 
 ABDOMINAL WALL, intercostal nerves, and of the first lumbar. They 
 have the same general course and distribution. They run forwards 
 under the costal cartilages between. the internal oblique and trans- 
 versalis towards the rectus. They furnish branches to the ab- 
 dominal muscles, and each gives off its lateral and anterior cu- 
 taneous branches, described p. 150. 
 
 The transversalis muscle must now be reflected 
 with the rectus* by incisions similar to those for 
 the reflection of the aponeurosis of the external oblique. The 
 parts must be disturbed as little as possible, so that the bearing 
 of the transversalis fascia in reference to the anatomy of the parts 
 concerned in hernia may be thoroughly examined. 
 
 DISSECTION OF THE PARTS CONCERNED IN INGUINAL HERNIA. 
 
 FASCIA TKANS- This fascia is so called because it lies in contact 
 VERSALIS. with the posterior surface of the transversalis 
 
 muscle. It is comparatively thin, superiorly, where it is conti- 
 nuous with the fascia on the under surface of the diaphragm. 
 
PAETS CONCERNED IN INGUINAL HERNIA. 
 
 365 
 
 Inferiorly, it is attached to the crest of the ilium and to Poupart's 
 ligament, where it becomes continuous with the fascia covering the 
 iliacus internus (fascia iliaca). About the middle of Poupart's 
 ligament it sends a funnel-shaped prolongation downwards into 
 the thigh, forming the anterior part of the sheath of the femoral 
 vessels. Its inner border is connected with the margin of the 
 rectus, to the lower margin of the conjoined tendon, and also 
 to the pubes. This fascia is strongest just behind the external 
 
 FIG. 73. 
 
 1. Internal abdominal 
 
 ring. 
 
 2. Position of the ex- 
 
 ternal abdominal 
 ring in dotted out- 
 line. 
 
 3. Epigastric a. in 
 
 dotted outline. 
 
 4, 4. Sheath of the femo- 
 ral vessels, con- 
 tinued from the 
 fascia transver- 
 salis. 
 
 5. Femoral a. 
 
 6. Profunda a. 
 
 7. Saphena v. 
 
 8, 8. Fascia transyer- 
 salis. 
 
 DIAGRAM OF THE FASCIA TKANSVEESALIS SEEN FROM THE FRONT. 
 
 abdominal ring, and, but for it and the conjoined tendon, there 
 would be a direct opening into the abdominal cavity through 
 the external ring. The outer half of the fascia is very firmly 
 connected to Poupart's ligament and to the fascia iliaca; but 
 the inner half is loosely connected with the crural arch, and passes 
 down under it, as before stated, over the femoral vessels into the 
 thigh, and forms the front of what is termed the femoral sheath. 
 
 INTERNAL As- The opening in the fascia transversalis through 
 
 DOMINAL BING. which the spermatic cord passes is called the 
 
366 PARTS CONCERNED IN INGUINAL HERNIA. 
 
 internal abdominal ring (or the inner aperture of the inguinal 
 canal). It corresponds to a point midway between the anterior 
 superior spine of the ilium and the spine of the pubes, and about 
 two- thirds of an inch above the crural arch. It is oval with the 
 long diameter nearly vertical ; its margin is well defined on the 
 inner, but not on the outer side, and from its border is continued 
 forwards a funnel-shaped prolongation over the spermatic cord, 
 which passes through the ring. This covering, thin and delicate, 
 is termed the infundibuliform fascia. (This is not seen in the 
 diagram.) Close by the inner border of the internal ring, the deep 
 epigastric artery ascends 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 situ- 
 ated immediately behind it. The peritoneum at the inner ring 
 presents a well-marked depression, which varies, however, consi- 
 derably : 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 is found between the general 
 cavity of the peritoneum and the tunica vaginalis testis. 
 
 INGUINAL Having examined the several strata through 
 
 CANAL. which the spermatic cord passes, replace them in 
 
 their natural position, and examine the inguinal canal as a whole. 
 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, 
 and externally by a small portion of the internal 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, by the crural 
 arch. 
 
 p From a surgical point of view this is one of the 
 
 EELATIONS OF THE most important arteries in the body. It arises 
 DEEP EPIGASTRIC from the external iliac, just before this vessel 
 AETEEY. passes under the crural arch. It ascends inwards 
 
PARTS CONCERNED IN INGUINAL HERNIA. 367 
 
 between the fascia transversalis and the peritoneum, forms a gentle 
 curve on the inner side of the internal abdominal ring, and conse- 
 quently on the inner side of the spermatic cord, and then enters 
 the rectus muscle below the edge of the sheath. 
 
 The artery runs in the substance of the rectus parallel with the 
 linea alba, and is accompanied by two veins, of which the larger is 
 on its inner side. They terminate by a single trunk in the iliac 
 vein. 
 
 BRANCHES OF The pubic is the most important branch. It 
 
 THE DEEP EPI- runs inwards, behind the crural arch, towards the 
 GASTHIC. pubes, behind which it anastomoses with the pubic 
 
 branch of the obturator. Sometimes the obturator artery is absent, 
 in which case the pubic branch of the epigastric enlarges and takes 
 the place of the absent vessel. It derives its chief practical in- 
 terest from the fact that it is liable to be wounded in dividing the 
 stricture in femoral hernia.* But its size varies in different sub- 
 jects, and is sometimes so small as to escape observation. The 
 second branch is the cremasteric. It supplies the coverings of the 
 cord, but chiefly the cremaster muscle. After giving off other 
 unnamed muscular branches the main trunk terminates in the 
 rectus by inosculations with the internal mammary. 
 
 DEEpCmcuM- The deep circumflexa ilii artery is a branch of 
 
 FLEXA lui. the external iliac, just above the crural arch ; it 
 
 runs upwards and outwards parallel with Poupart's ligament, and 
 at the middle of the crest of the ilium pierces the transversalis 
 muscle, and, running in the same direction, lies between the 
 transversalis and internal oblique. It anastomoses with the ilio- 
 lumbar artery, and sends small muscular branches, which run 
 upwards, and communicate with the epigastric and the lumbar 
 arteries. 
 
 The circumflex iliac vein crosses the external iliac artery and 
 opens into the external iliac vein. 
 
 Such is an outline of the anatomy of the parts concerned in 
 
 * There is a preparation (No. 83, Ser. 17) in the Museum of St. Bartholomew's 
 Hospital quite to the point. The patient had profuse haemorrhage, which com- 
 menced five hours after the operation. He died from peritonitis. 
 
368 PARTS CONCERNED IN INGUINAL HERNIA. 
 
 inguinal hernia. The description applies equally to the female, 
 provided the round ligament be substituted for the spermatic 
 cord. The inguinal canal is proportionately smaller, and there 
 is no cremaster. 
 
 PRACTICAL The testis originally formed in the loins passes, 
 
 APPLICATION. about the eighty month of foetal life, from the 
 
 abdomen into the scrotum, through an oblique canal in the wall 
 of the abdomen, called the inguinal canal. A portion of peri- 
 toneum is pouched out before the descending testis, and consti- 
 tutes the tunica vaginalis testis, "The blood-vessels, nerves, and 
 vas deferens pass down with the testis, and constitute the sper- 
 matic cord. The inguinal canal runs obliquely through the abdo- 
 minal wall, that it may the better resist the protrusion of intestine. 
 
 The wall of the abdomen, as previously stated, is composed of 
 various strata, and the testis and cord in their passage through 
 each stratum derive from each a covering similar in structure to 
 the stratum itself. Of these strata there are three : the first, 
 proceeding from within outwards, is the fascial stratum derived 
 from the fascia transversalis ; the second is the muscular stratum 
 (cremasteric) from the internal oblique and transversalis muscles ; 
 the third is the aponeurotic stratum from the external oblique. 
 
 The passage of the testis through the lower part of the ab- 
 dominal parietes (inguinal canal) occasions, at this part of the 
 belly, a natural weakness which, associated with other conditions, 
 favours the protrusion of intestine in this situation. 
 
 A protrusion of intestine through any part of the inguinal canal 
 is called an inguinal hernia. 
 
 OBLIQUB The most common form of inguinal hernia is 
 
 INGUINAL HEENIA. that in which a portion of intestine protrudes 
 first through the internal ring, then, traversing the inguinal 
 canal, emerges through the external ring, and thence may descend 
 into the scrotum. This variety is called an oblique inguinal 
 hernia.* If the intestine stops within the inguinal canal, it 
 
 * A hernia is sometimes called external or internal, according to the relation 
 of the protrusion to the deep epigastric artery: thus, an oblique inguinal hernia which 
 first protrudes through the inner ring is called an external hernia, and vice -versa. 
 
ANATOMY OF PARTS CONCERNED IN HERNIA. 369 
 
 is called an incomplete inguinal hernia ; if, however, the pro- 
 trusion has emerged through the external ring, it is called a com- 
 plete inguinal hernia ; and, lastly, if it descends into the scrotum, 
 it is called a scrotal hernia. 
 
 DIRECT INGOT- The intestine, however, does not always escape 
 NAL HERNIA, through the internal ring. Sometimes it protrudes 
 
 internal to the deep epigastric artery through a triangular weak 
 place, bounded on the inner side by the rectus, on the outer side 
 by the deep epigastric artery, and below by Poupart's ligament. 
 This space* is relatively weak, having in front of it only the fascia 
 transversalis and the conjoined tendon of the internal oblique and 
 transversalis ; moreover, it is situated immediately behind the ex- 
 ternal abdominal ring. A portion of intestine protruding through 
 this triangle comes directly forwards through the external ring, and 
 the hernia is then called a direct inguinal hernia. 
 
 COVERINGS OF A complete oblique inguinal hernia, passing as 
 
 AN OBLIQUE IN- it does through the same structures as the testis 
 GUINAL HEBNIA. ^ j^ f^ai life., receives the same coverings as 
 that gland ; they are : 
 
 1. The skin and the superficial fascia. 
 
 2. The inter columnar fascia, derived from the external oblique. 
 
 3. The cremaster derived from the internal oblique and transversalis. f 
 
 4. The infundibuliform fascia, derived from the fascia transversalis. 
 
 5. The subperitoneal fat, and the peritoneum which constitutes the 
 sac. 
 
 An incomplete oblique inguinal hernia is covered by 
 
 1 . The skin and superficial fascia. 
 
 2. The aponeurosis of the external oblique. 
 
 3. The cremaster. 
 
 4. The infundibuliform fascia. 
 
 5. The sub peritoneal fat and the peritoneum. 
 
 COVERINGS OF A -A- direct inguinal hernia protrudes immediately 
 DIRECT INGUINAL on the inner side of the epigastric artery through 
 HERNIA. fa e ex t e rnal ring ; and its course forwards is mainly 
 
 * Sometimes called Hesselbach's triangle, 
 f The cremaeter muscle is absent in the female. 
 B 
 
370 ANATOMY OF PARTS CONCERNED IN HERNIA. 
 
 prevented by the resistance of the conjoined tendon.* This 
 hernia is covered by 
 
 1. The skin and superficial fascia. 
 
 2. The intereolumnar fascia. 
 
 3. The conjoined tendon of the internal oblique and transversalis. 
 
 4. The fascia transversalis. 
 
 5. The subperitoneal fat and the peritoneum. 
 
 In almost all cases, the immediate investment of the intestine 
 is the parietal layer of the peritoneum. This constitutes the sac 
 of the hernia, 'The opening of the sac, communicating with the 
 abdomen, is called its mouth ; then comes the narrow, con- 
 
 FIG. 74. 
 
 VARIETIES OF CONGENITAL INGUINAL HERNIA, CONSEQUENT UPON SOME DEFECT IN THE 
 DEVELOPMENT OF THE SPERMATIC PORTION OF THE TUNICA VAGINALIS, THE 
 ARROWS MARK THE PROTRUSION. 
 
 1. Hernia in the tunica vaginalis testis. 3. Infantile hernia. 
 
 2. Hernia in the funicular portion of the tunica 4. Encysted hernia. 
 
 stricted portion, or neck ; and lastly, the body, or expanded part 
 of the sac. 
 
 CONGENITAL Owing to the comparatively late descent of the 
 
 HERNUE. testis in foetal life, it frequently happens that 
 
 either no closure, or only a partial closure, takes place in the vaginal 
 portion of the tunica vaginalis. Under these conditions, when a 
 protrusion takes place, the intestine does not push forwards a sac 
 derived from the parietal layer of the peritoneum, but it lies in a 
 
 * In our experience the weakness of the conjoined tendon is, anatomically speak- 
 ing, the determining cause of this form of hernia. 
 
ANATOMY OF PARTS CONCERNED IN HERNIA. 371 
 
 sac formed by the tunica vaginalis, which still communicates with 
 the peritoneal cavity. These hernise are always oblique, and are 
 termed congenital.* There are four varieties, all of which are the 
 result of, or associated with, some congenital defect. They are as 
 follows : 
 
 1. Hernia in the tunica vaginalis testis. ^-This occurs when a protru- 
 sion of intestine takes place through the narrow canal which persists 
 between the general cavity of the peritoneum and the tunica vaginalis 
 testis, in consequence of the non-obliteration of the original communica- 
 tion between them. In this case, the intestine surrounds the testis, and 
 the sac is formed by the tunica vaginalis testis (fig. 74. 1.). 
 
 2. Hernia in thefunicular portion of the tunica vaginalis occurs when 
 an incomplete closure of the tunica vaginalis takes place immediately 
 above the testis ; the canal above it being still unclosed and communi- 
 cating with the peritoneal cavity. The sac is formed by the original 
 pouch of the peritoneum in the descent of the testis, although shut off 
 from the tunica vaginalis testis by a thin septum (fig. 2). 
 
 3. Infantile hernia is rare, and occurs when the original peritoneal 
 canal is occluded at the inner ring, so that the tunica vaginalis testis 
 reaches up as high as the canal, or even as far as the internal ring. The 
 intestine in this variety protrudes a sac through the inner ring, but behind 
 this abnormal extension of the tunica vaginalis ; so that in front of the 
 hernia there are three layers of peritoneum : two formed by the tunica 
 vaginalis, the third by the sac (fig. 3). 
 
 4. Encysted hernia is still rarer than the preceding, and may occur 
 in those cases in which the closing septum at the internal ring is so thin 
 that an advancing hernia pushes before it this thin stratum (which 
 forms its sac) as a diverticulum into an unclosed tunica vaginalis '(fig. 4). 
 
 POSITION OF The spermatic cord is generally situated behind 
 
 SPERMATIC COED. an ^ ^ o foe outer side of a hernial sac. In some 
 cases, however, the hernia separates the constituents of the cord, 
 so that one or other of these comes to lie in front of the protrusion. 
 
 SEAT OF The stricture may be seated either at the ex- 
 
 STBICTCBE. ternal ring, the internal ring, at any intermediate 
 
 * 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. 
 
 B B 2 
 
372 ANATOMY OP PARTS CONCERNED IN HERNIA. 
 
 part between these, or at the neck of the sac. Sometimes there 
 is a double stricture, one at the external ring, the other at the 
 internal. 
 
 As stated, the stricture may be caused by the neck of the sac, 
 independently of the parts outside it ; for the peritoneum may 
 become thickened and indurated, and sufficiently unyielding to 
 strangulate the protruded intestine. The strangulation in a con- 
 genital hernia is nearly always caused by the neck of the sac itself. 
 
 In dividing the stricture, the surgeon should, in all cases, 
 adhere to the golden rale laid down by Sir Astley Cooper namely, 
 to divide it directly upwards. In this direction, there is the least 
 likelihood of wounding the deep epigastric artery. 
 
 CHANGES PRO- Whoever has the opportunity of dissecting an 
 DUCED BY AN OLD old hernia, of some size, will observe that the 
 AND LARGE obliquity of the inguinal canal is destroyed. The 
 
 constant dragging of the protruded viscera upon 
 the inner margin of the internal ring gradually approximates 
 the internal ring 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 deep epigastric artery with 
 regard to the sac remains unaltered. It is still on the inner side 
 of the neck of the sac. 
 
 In hernise of long standing, all its coverings undergo a change. 
 They become thickened and hypertrophied, and so altered from 
 what they once were that they scarcely look like the same parts. 
 
 D Expose the contents of the abdomen, by an in- 
 
 cision 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. 
 
 TT Behind the linea alba, the peritoneum is raised 
 
 into a fold by a fibrous cord, passing from the 
 
POSITION OF ABDOMINAL VISCERA. 373 
 
 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 inclosing cords 
 which ascend obliquely towards the umbilicus : these are the im- 
 pervious remains of the hypogastric arteries. 
 
 Take now a survey of the viscera before they are disturbed from 
 their relative positions. 
 
 WHAT is SEEN In the right hypochondrmm the liver is seen 
 
 ON OPENING THE projecting more or less below the cartilages of the 
 ABOOMEN. rifeS) and the fundus of the gall-bladder below the 
 
 edge of the liver, near the end of the ninth costal cartilage. In the 
 left hypochondrium is seen more or less of the stomach according 
 to its distension. Across the umbilical region extends a broad fold 
 of the peritoneum containing fat, the great omentum, which 
 descends from the lower curvature of the stomach, forming 
 a curtain over the convolutions of the small intestine. The 
 breadth of this fold varies ; sometimes being so shrunk and 
 crumpled as to be scarcely visible. The lower part of the abdomen 
 and part of the pelvis are occupied by the small intestine. 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 descend- 
 ing part of it in the left, are not visible unless distended : they lie 
 contracted at the back of the abdomen. Such 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. 
 
 PABTICULAB The position of each viscus should now be ex- 
 
 POSITION OF amined separately, and first that of the stomach. 
 
 The stomach is irregularly conical in shape. Its 
 
 THE STOMACH. g re at 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. 
 
374 POSITION OF ABDOMINAL VISCERA. 
 
 The relative position and size of the stomach vary according to the 
 amount of distension ; 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 following peritoneal folds are attached to the stomach : 1. the 
 great omentum already described ; 2. the gastro-hepatic or lesser 
 omentum, which connects the lesser curve of the stomach with the 
 transverse fissure of the liver ; and 3. the gastro-splenic omentum, 
 which connects the great end of the stomach with the spleen. 
 
 -~ The first part of the intestinal canal is termed 
 
 intestinum duodenum, because it is about the 
 breadth of twelve fingers. Commencing at the pyloric end of the 
 stomach, the duodenum ascends as high as the neck of the gall- 
 bladder ; then turning downwards it passes 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 the duodenum describes 
 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 
 ascending, 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. 
 
 JEJUNUM AND Pursuing its course from the left side of the 
 
 ILEUM. second 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 con- 
 volutions, the upper two-fifths constitute the 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 sub- 
 stantial to the feel. 
 
POSITION OF ABDOMINAL VISCEKA. 
 
 375 
 
 COMMENCE- 
 MENT OF LAEGE 
 INTESTINE. 
 
 In the right iliac fossa, the small intestine 
 opens into the left side of the colon, which is 
 easily recognised * by its sacculated appearance : 
 here the large intestine begins : here is the ilio-cascal valve 
 (fig. 75). Immediately below the junction, the large intestine is 
 expanded into a blind pouch, called the ccecum or caput coli. 
 Into the back part of this pouch opens a little tube closed at the 
 other end, called the appendix vermiformis. This tube is gene- 
 rally three inches long, about as thick as a large earthworm, and 
 
 FIG. 75. 
 
 1. Heum. 
 
 2. Csecum or caput coll. 
 
 3. Appendix vermi- 
 form is. 
 
 SECTION THROUGH THE JUNCTION OP THE LABGE AND SMALL INTESTINE TO SHOW THE 
 ILIO-OZECAL VALVE AND APPENDIX VERMIFOBMIS. 
 
 is either coiled up behind the ca3cum, or connected to it by a 
 peritoneal fold, so as to hang loose in the pelvis. The commence 
 ment of the large intestine is generally confined by the peri- 
 toneum 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 as high as the under surface of the liver, where it 
 
 * But this is not invariably so. The bowel is, in some subjects, connected to the 
 fossa by a fold of peritoneum or a meso-ccecum. I have seen this fold sufficiently 
 loose to allow the caput coli to travel over to the left iliac fossa. 
 
376 
 
 POSITION OF ABDOMINAL VISCEEA. 
 
 makes a bend the hepatic flexure and crosses the umbilical 
 region towards the left side. Having reached the lower border 
 of the spleen, it makes another bend downwards, forming the sple- 
 nic flexure of the colon ;* thence it descends in front of the left 
 kidneyf through the left lumbar region into the left iliac fossa, 
 where it curves like the letter S. These successive portions of the 
 large intestine are termed, respectively, the ascending, transverse, 
 descending, 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 misapplied ; the canal runs anything but a straight course 
 through the pelvis, since it curves to adapt itself to the sacrum. 
 
 FIG. 76. 
 
 RELATIVE POSITION OF THE KIDNEYS AND THE LARGE INTESTINE SEEN 
 FEOM BEHIND. 
 
 L. K. Left kidney, crossed obliquely by the last 
 
 dorsal artery and nerve. 
 R. K. Bight kidney. 
 
 A. c. Ascending colon 
 D. c. Descending colon. 
 
 Looking at the entire course of the colon, observe that it forms 
 an arch, of which the concavity embraces the convolutions of the 
 small intestines. 
 
 * 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 kid- 
 ney respectively, explains the occasional bursting of renal abscesses into the intesti- 
 nal canal. 
 
POSITION OP ABDOMINAL VISCEEA. 377 
 
 LENGTH OF THE 1^ e small intestine, including the duodenum, 
 ALIMENTAET varies from sixteen to twenty-four feet in length, 
 
 CANAL. an d the large intestine 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, the 
 small and large intestines are from five to six times the length of 
 the body, 
 
 SITUATION OF The liver occupies the^ whole of- the right hypo- 
 
 THE LIVEB. chondrium, and extends over the epigastric region 
 
 more or less into the left. Unless the individual be very corpu- 
 lent, we can ascertain during life the extent to which the liver pro- 
 jects 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 upper surface ascends 
 as high as the fifth intercostal space ; its under surface overlies 
 part of the stomach, of the duodenum, of the right kidney, of the 
 transverse colon, and of the supra-renal 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 falciform ligament, 
 is situated a little to the right of the mesial line. The lower and 
 free edge of it contains the impervious remains of the umbilical 
 vein, called the round ligament. The suspensory ligament, traced 
 backwards, leads to another broad fold extending horizontally from 
 the diaphragm to the posterior border of the liver ; this Consti- 
 tutes the lateral ligament, right or left, according as we trace it on 
 one or the other side of the falciform ligament. 
 
 The junction -of the lateral and falciform ligaments is described 
 by some authors as the coronary ligament. 
 
 SITUATION OF THE The gall-bladder is the reservoir for the bile, 
 GALL-BLADDER. g^ j s c l ose ly confined by the peritoneum in a 
 slight depression on the under surface of the right lobe of the liver. 
 Its lower end or fundus projects beneath the cartilage of the ninth 
 rib. This is important practically. It sometimes happens that 
 
378 POSITION OF ABDOMINAL VISCEKA. 
 
 the gall-bladder, in consequence 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 duo- 
 denum and the transverse colon explains the occasional evacuation 
 of gall-stones by ulceration into the intestinal canal.f 
 
 SITUATION OF The spleen is deeply situated in the left hypo- 
 
 THE SPLEEN. chondrium, between the stomach and the ninth, 
 
 tenth, and eleventh ribs. It is- placed nearly vertically ; its 
 outer surface is smooth and convex, to correspond with the dia- 
 phragm 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 gastro-splenic omentum. Generally, 
 too, the spleen is connected by a small peritoneal fold, the suspen- 
 sory ligament, to the under surface of the diaphragm.^ Below, the 
 spleen is in contact with the kidney and the descending colon. 
 
 SITUATION OF This is the salivary gland of the abdomen. It 
 
 THE PANCREAS. ii es behind the. stomach, transversely across the 
 spine, about the level" of the first lumbar vertebra. Its right end 
 or head is contained 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 at this stage of the dissection 
 be satisfactorily seen. 
 
 SITUATION OF The kidneys are situated in the lumbar region, 
 
 THE KIDNEYS. nearly opposite the two lower dorsal and the two 
 
 upper lumbar vertebrae ; the right, owing to the size of the liver, 
 being a little lower;- than, the left. They lie embedded 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 Aodral,' Clin. Jied.' 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. 
 
PERITONEUM. 379 
 
 SITUATION OF This body is situated at the top of the kidney. 
 
 THE SUPBA-BENAL It lies upon the crus of the diaphragm. You will 
 CAPSULE. gee fae right supra-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 
 PEBITONEUM. . 3 . J 
 
 the abdominal viscera, they are provided with a 
 
 serous membrane, called the peritoneum. This membrane, like 
 other serous membranes, is a closed sao, one part of which lines the 
 containing 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 endothelium: the external 
 surface, the sub-peritoneal tissue, is composed of areolar tissue 
 which connects the internal layer to the invested viscus or ab- 
 dominal 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 supra-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. 
 
 COUBSEOFTHE Now trace the peritoneum as a continuous 
 PEBITONEUM. membrane. Since the peritoneum is a perfect sac, 
 
 it matters not where we begin : we must come back to the starting- 
 point. 
 
 If a longitudinal section be made through the viscera in the 
 middle of the body, one can trace the peritoneum thus beginning 
 at the diaphragm, and taking, for brevity's sake, two layers at a 
 time (fig. 77). 
 
380 
 
 PEEITONEUM. 
 
 From the diaphragm two layers of peritoneum proceed to the 
 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 
 FIG. .7.7. its greater curve, pass down like a 
 
 curtain over the small intestine 
 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-fr-ont 
 of the transverse colon, which they 
 inclose, and, after joining again at 
 the back of the colon, proceed to 
 the spine, forming the transverse 
 meso-coloru At this situation the 
 two layers diverge, 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 in- 
 testine, 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 
 
 DIAGRAM OF THE PERITONEUM. 
 
 * 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 fetus grows, 
 the great omentum becomes adherent to the arch of the colon. 
 
PEEITONEUM. 381 
 
 bladder, forming the recto-vesical pouch, and thence to the wall of 
 the abdomen, along which it can be traced up to the diaphragm. 
 In the female, it is reflected from the rectum on to the posterior 
 wall of the vagina half an inch from the uterine extremity, consti- 
 tuting 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 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: namely, the descending and transverse 
 portions of the duodenum, the caecum, the ascending and descend- 
 ing colon (with exceptional cases), and 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), the lesser cavity 
 becomes distended ; 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 transverse meso-colon ; above, by the liver. 
 
 FORAMEN OF This foramen is the narrow circular opening 
 
 WINSLOW. between the greater and 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. 
 
382 
 
 PEEITOISTEUM. 
 
 The several folds, formed by the reflections of the peritoneum, 
 which connect the viscera, either to each other or to the back of 
 the abdomen, have now to be examined. 
 
 FIG. 78. 
 
 O.P. Greater cavity of 
 the peritoneum. 
 
 L.P. Leaser cavity of 
 the peritoneum. 
 
 A. Aorta. 
 
 St. Stomach. 
 
 s. Spleen. 
 
 v. Inferior vena cava. 
 
 L. Liver. 
 
 DIAGRAM OF A TRANSVERSE SECTION THROUGH THE UPPER PART OF THE 
 ABDOMINAL CAVITY SEEN FROM ABOVE. 
 
 MESENTERY. 
 
 This is the fold which suspends the small in- 
 testine from the back of the abdomen. To see it, 
 raise the great omentum and the transverse arch of the colon. Its 
 
 FIG. 79. 
 
 o.o. The great omen 
 turn, with its ca- 
 vity. 
 
 i. Small intestine. 
 
 A. Aorta. 
 
 v. Inferior vena cava. 
 A.c. Ascending colon. 
 D.C. Descending colon. 
 K. Kidneys. 
 
 DIAGRAM OF A TRANSVERSE SECTION THROUGH THE LOWER PART OF THE 
 ABDOMINAL CAVITY. 
 
 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 is very broad, and curves like 
 
PERITONEUM. 383 
 
 a ruffle, inclosing the small intestine from the beginning of the 
 jejunum to the end of the ileum. We must trace between its two 
 layers, the mesenteric vessels, nerves, glands, and lymphatics. 
 
 TRANSVERSE This broad fold connects the transverse colon to 
 
 MESO-COLON. the back of the abdomen. It forms an imperfect 
 
 partition dividing the abdomen into an upper compartment, con- 
 taining 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 are, as a 
 general rule, bound down by the peritoneum in their respective 
 situations (fig. 79). The peritoneum covers only two-thirds or 
 thereabouts of their anterior surface; their posterior surface is con- 
 nected by loose cellular tissue to the back of the abdomen.* The 
 colon, ascending or descending, can therefore be opened in the 
 lumbar region, below the kidney, without injury to the peritoneum : 
 a fact upon which is founded the operation of colotomy for the 
 relief of stricture of the rectum. 
 
 GREAT This broad peritoneal fold is composed of four 
 
 OMENTUM. layers, and proceeds from the lower border of the 
 
 stomach, like a curtain over the convolutions of the small intestine. 
 Its thickness varies considerably ; in thin subjects it is often 
 translucent; in corpulent 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 
 extending low into the pelvis ; in others, small and crumpled. 
 
 GASTRO- This fold passes from the transverse fissure on 
 
 HEPATIC OR the under surface of the liver to the upper curve 
 
 LESSER OMENTUM. of the stomach> j t is composed of two layers, and 
 
 between them are the portal vein and hepatic artery with the nerves 
 going to the liver, and the hepatic duct and lymphatics coming from 
 it. The right border of this 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 
 
 * In some (rare) cases, the ascending and descending colon (more commonly the 
 latter) are completely surrounded by peritoneum, and connected to the lumbar regions, 
 respectively, by a right and left lumbar meso-colon. 
 
384 
 
 PERITONEUM. 
 
 them. If the finger be introduced behind the right border, it 
 passes through the foramen of Winslow into the lesser cavity of the 
 peritoneum. 
 
 GASTBO- ^his ^^ proceeds from the great end of the 
 
 SPLENIC OMEN- stomach to the spleen, and is continuous below 
 TUM. with the great omentum. It contains between its 
 
 layers the branches, vasa brevia, which proceed from the splenic 
 artery to the great end of the stomach. 
 
 FIG. 80. 
 
 1. Phrenic. 
 
 2. Cceliacaxis. 
 
 3. Superior mesenteric. 
 
 4. Supra-renal. 
 
 5. Renal. 
 
 6. Spermatic. 
 
 7. Inferior mesenteric. 
 
 8. Lumbar. 
 
 9. Sacra media. 
 
 BBANCHES OF THE ABDOMINAL AOETA. 
 
 The reflections of the peritoneum from the liver to the abdo- 
 minal walls, forming its ligaments, have been described in tracing 
 the connections of that organ (p. 377). 
 
 BEANCHES OF Our next object should be the examination of 
 
 THE ABDOMINAL the arteries which supply the viscera. The aorta 
 AoRTA - enters the abdomen between the pillars of the 
 
 diaphragm in front of the last dorsal vertebra, and then, descending 
 
BRANCHES OP THE ABDOMINAL AORTA. 385 
 
 a little to the left side of the spine, divides on the fourth lumbar 
 vertebra into the two common iliac arteries. In this course it 
 gives off its branches in the following order (fig. 80) : 
 
 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- 
 testine and the upper half of the large. 
 
 4. 5. The supra-renal and the renal arteries. 
 
 6. The spermatic, for the testicles ; the ovarian, for the ovaries. 
 
 7. The inferior mesenteric, for the supply of the lower half of 
 the large intestine. 
 
 8. The lumbar, four branches analogous to the intercostals, for 
 the supply of the back part of the abdomen. 
 
 9. The artena sacra media, which is given off at the bifurca- 
 tion of the aorta, supplies the fifth lumbar artery and, running 
 down in front of the sacrum, the lateral sacral arteries. 
 
 These branches are to be traced throughout in 
 the order most convenient. Take the coeliac axis 
 first. To dissect this artery and its branches, the liver must be 
 well raised, as in fig. 81, and the anterior layer of peritoneum 
 removed from the gastro-hepatic omentum. A close network 
 of very tough tissue surrounds the visceral branches of the 
 aorta. This tissue consists almost entirely of plexuses of nerves, 
 derived from the sympathetic system, each plexus taking the name 
 of the artery which it surrounds. Of these plexuses, the largest 
 surrounds the cceliac axis like a ring. This is the solar plexus, 
 and is formed by the junction of the two semi-lunar ganglia (see 
 dissection of thorax, p. 147). 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 plexuses receiving the names of 
 the arteries around which they twine. It requires a lean subject 
 and much patience to trace them. 
 
 C 
 
BRANCHES OF THE CCELIAO AXIS. 
 
 PLAN OF THE BEANOHES OF THE CCELIAC AXIS. 
 
 C Coronaria ventri- f" cesophageal. 
 culi. \ gastric. 
 
 CffiLIAC AXIS 
 
 i 
 
 I Hepatic 
 
 Splenic 
 
 pyloric. . [gastro-epiploica dextra. 
 
 gastro-duodenalis. -j pancreatico-duodenalis 
 cystic. I superior. 
 
 pancreatic branches, 
 gastro-epiploica sinistra. 
 vasa brevia to stomach. 
 
 C<ELIAC AXIS 
 AND ITS 
 
 BRANCHES. 
 
 The coeliac axis arises from the front of the 
 aorta, between the pillars of the diaphragm, im- 
 mediately above the upper border of the pancreas, 
 and to the left of the lobulus Spigelii. It is a very thick, short 
 trunk, which runs between the two layers of the lesser omentum, 
 and, after a course of about half an inch, divides into three 
 branches the coronaria ventriculi, the splenic, and the hepatic. 
 
 COBONABIA The coronaria ventriculi^ the smallest of the 
 
 VENTKICTLL three, ascends a little to the left towards the 
 
 cesophageal end of the stomach, where it gives off cesophageal 
 branches, which inosculate with the cesophageal branches of the 
 thoracic aorta. It then runs along the lesser curvature of the 
 stomach towards the pylorus, and anastomoses with the pyloric 
 branch of the hepatic artery. 
 
 HEPATIC The hepatic artery ascends to the right between 
 
 ABTEBT. t, ne 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 half 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. 
 
 b. The gastro-duodenalis, passing behind the ascending portion of the 
 
BLANCHES OF THE CCELIAC AXIS. 
 
 387 
 
 duodenum, divides into (a) the gastro-epiploica dextra, which runs along 
 the greater curve of the stomach, from right to left, and anastomoses 
 with the gastro-epiploica sinistra from the splenic ; and (/3) the pancrea- 
 tico-duodenalis superior, which runs down between the head of the pan- 
 creas and the descending portion of the duodenum, and anastomoses with 
 the pancreatico-duodenalis inferior, a branch of the superior mesenteric. 
 c. The cystic, commonly a branch of the right hepatic, divides into 
 two branches, one of which ramifies on the under surface of the gall- 
 
 Fio. 81. 
 
 _ Spleen. 
 
 Descending 
 duodenum . 
 
 Termination 
 of bile-duct. 
 
 Commencement of the intesti- 
 num jejunum. 
 
 DIAGEAM OF THE BRANCHES OF THE CO3UAC AXIS. 
 
 (Pancreas in dotted outline behind the stomach.) 
 
 1. Coronaria ventriculi. 
 
 2. Splenic a. 
 
 3. Hepatic a. 
 
 4. Pyloric a. 
 
 5. Gastro-duodenalis. 
 
 6. Gastro-epiploica sinistra. 
 
 7. Vasa brevia. 
 
 8. Superior mesenteric a. 
 
 bladder, the other passes between the liver and the upper surface of the 
 gall-bladder. 
 
 The splenic, the largest of the three, proceeds 
 tortuously towards the left side, above its corre- 
 c c- 2 
 
 SPLENIC 
 A BTBRT. 
 
388 
 
 VENA POETJE. 
 
 spending vein, along the upper border of the pancreas to the spleen, 
 which it enters by numerous branches. 
 
 It gives off: 1. Several small branches to the pancreas, pancreaticce 
 parvce. One, rather larger than the rest, which accompanies the pan- 
 creatic duct, is called pancreatica magna. 2. The gastro-epiploica 
 sinistra, which runs to the right along the great curve of the 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 ventriculi, and the gastro-epiploica sinistra. 4. The splenic 
 branches are five or six in number, and enter the fissure of the spleen. 
 
 Thus the stomach is 
 supplied with blood by four 
 channels, which by their 
 inosculations form a main 
 artery along its lesser 
 curve, another along its 
 greater ; from these, nu- 
 merous branches are fur- 
 nished to both surfaces of 
 the stomach. The artery 
 of the greater xwrve also 
 sends down numerous omen- 
 tal branches, which form a 
 network between the layers 
 of the great omentum. 
 
 VENA POBTJE : The veins 
 
 ITS PECULIAEITIES. which re- 
 
 turn the blood from the 
 abdominal portion of the 
 alimentary canal, the pan- 
 creas, and the spleen, do 
 not empty themselves into 
 the vena cava inferior, but 
 all unite into one large 
 vein, called the vena portce, which ramifies throughout the liver, 
 
 DIAGRAM OF THE VKNA POBT^K. 
 
 (The arrow is introduced behind the free 
 border of the lesser omentum.) 
 
VENA PORTSE. 389 
 
 and secretes the bile. The trunk of the vena portse itself is 
 about three inches long. Tracing it downwards you find that 
 it is formed behind the great end of the pancreas, by the con- 
 fluence of the splenic and superior mesenteric veins (fig. 82). 
 In its passage to the liver, the vena portse is accompanied by 
 the hepatic artery and the common bile-duct, lying behind and 
 between them. At the transverse fissure of the liver it divides 
 into two branches corresponding to the right and left lobes. 
 The vein ra-mifies in the substance of the liver like an artery, 
 and is surrounded, with the branches of the hepatic artery and 
 duct, in a sheath of areolar or fibrous tissue called 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 venae cavse hepaticae. 
 
 The veins which empty themselves into the vena portse have 
 no valves. Therefore, if any obstruction 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 hsemorrhoids, 
 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 the right lobe and the- other from the left : 
 it is soon joined by the cystic duct from the gall-bladder. The 
 common duct, ductus communis choledochus, thus formed, passes 
 between the two layers of the lesser omentum close to its right 
 border, then behind the first portion of the duodenum, and opens 
 obliquely into the back part of the second portion, near the junc- 
 tion with the third. The duct runs through the coats of the 
 bowel for nearly three-quarters of an inch (p. 387). As the common 
 bile-duct descends between the layers of the lesser omentum, it 
 lies in front of the vena portse, having the hepatic artery on its 
 left. The duct is about three inches long, and if distended would 
 be about the size of a crow-quill. 
 
390 
 
 MESENTERIC VESSELS. 
 
 DISSECTION. 
 
 The great omentum, with the arch of the colon, 
 must now be turned up over the chest, and the 
 small intestines pushed towards the left side. Then, by removing 
 the anterior layer of the peritoneum from the mesentery, we expose 
 the mode in which the superior mesenteric artery ramifies so as to 
 supply the small intestine. In making this dissection, the mesen- 
 teric glands immediately attract notice. They lie in great 
 numbers between the layers of the mesentery, and vary consider- 
 ably in size. The fine tubes, called lacteal vessels, which traverse 
 
 FIG. 83. 
 
 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 hsemorrhoidal 
 
 PLAN OF THE MESENTERIC AKTEEIES, AND THEIR COMMUNICATIONS. 
 
 the glands, are too thin and transparent 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 intestine.* After 
 traversing the glands, they all eventually empty their contents into 
 the receptaculum chyli (p. 142). 
 
 * The arrangement of the chyliferous vessels is well displayed in the plates of 
 Mascagai. 
 
MESENTERIC VESSELS. 391 
 
 SUPERIOR This large artery arises from the front of the 
 
 MESENTEBIC aorta, descends beneath the pancreas, in front of 
 
 ABTEBY AND the transverse part of the duodenum (p. 387), and 
 
 INCHES. then runs between the layers of the mesentery 
 
 towards the right iliac fossa, where it terminates in branches for 
 the supply of the caecum. Thus it describes a gentle curve from 
 left to right. It gives off the following branches : 
 
 1. The inferior pancreatico-duodenal branch, which runs tip, within 
 the concavity of the duodenum, to inosculate with the superior pancre- 
 atico-duodenal branch of the hepatic. 2. Vasa intestini tennis of the 
 small intestine, 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 for the supply 
 of the ileum, caecum, ascending, and transverse colon, respectively. 
 
 The student should now trace the branches to the small intes- 
 tine, in order to see the 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 csecum : 
 the right colic, which proceeds towards the ascending colon, and the 
 middle colic, which ascends between the layers of the meso-colon to the 
 arch. They are arranged after the same plan as those of the small in- 
 testine : that is, they inosculate and form a series of arches which suc- 
 cessively decrease in size and finally terminate in circles round the 
 bowel. 
 
 The superior mesenteric vein joins the splenic behind the pan- 
 creas, and forms the vena portse (p. 388), 
 
392 MESENTEEIC VESSELS. 
 
 To trace this artery, the small intestine must be 
 
 DISSECTION OF V 
 
 THE INFEBIOE drawn over towards the right side, and the peri- 
 MESENTERIC toneum covering the artery removed. It is given 
 
 ARTERY AND o ff f rom the front of the aorta, about two inches 
 
 above its bifurcation. Descending towards the 
 left iliac fossa, it crosses obliquely over the left common iliac 
 artery, passes between the layers of the meso-rectum, and, taking 
 the name of superior hcemorrhoidal, is finally distributed to the 
 upper part of the rectum. Its branches are : 
 
 1. The colica sinistra, which crosses behind the peritoneum, over the 
 left kidney, and supplies the descending colon. 
 
 2. The sigmoidea, which is distributed to the sigmoid flexure. 
 
 3. The superior hcemorrhoidal, which supplies the upper part of the 
 rectum, and will be dissected with the side view of the pelvis. 
 
 These branches of the inferior mesenteric inosculate in the form 
 of arches, like the colic branches of the superior mesenteric. 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. 83). 
 
 The inferior mesenteric vein ascends nearly vertically in front 
 of the left psoas, and 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. After the jejunum and the sigmoid flexure have been 
 divided between the ligatures respectively, the small and large 
 intestines can be removed. By turning up the stomach, we expose 
 the duodenum curving round the great end of the pancreas. 
 
 DUODENUM, The duodenum (p. 387) commences at the 
 
 EELATIONS OF. pyloric end of the stomach, and terminates on 
 the left side of the second lumbar vertebra, where the intestinum 
 jejunum begins. It is divided into three parts, an ascending, 
 descending, 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 
 
DUODENUM AND PANCEEAS. 393 
 
 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 of the second lumbar vertebra : here the intestine takes 
 the name of jejunum. Thus the duodenum describes a horse- 
 shoe curve, the concavity of which is directed towards the left 
 side, and embraces the head of the pancreas. 
 
 The first or ascending portion is about two inches long, and 
 is completely invested by peritoneum. It is comparatively free, 
 so that the movements of the stomach may not be restricted. 
 In front of it are the liver and gall-bladder. Behind it are the 
 bile-duct and the hepatic vessels. The second or descending por- 
 tion lies behind the transverse colon. Behind it are the common 
 bile-duct and the pancreatic duct, which empty themselves into 
 it either separately, or by a common opening. The descending 
 portion is covered with peritoneum only on its anterior surface. 
 The third or transverse portion is about four inches long, is 
 situated behind the transverse meso-colon, just above the mesen- 
 tery, and below the superior mesenteric artery and the pancreas. 
 It lies upon the aorta and inferior vena cava. This portion, like 
 the second, is only covered in front by peritoneum. Notice how 
 firmly the duodenum is braced up on the left side of the second 
 lumbar vertebra ; and how the jejunum begins here by an abrupt 
 downward bend. 
 
 PANCEEAS, This large gland is situated immediately be- 
 
 EELATIONS OF. m ' n d the stomach (p. 378.) It is of an elongated 
 form, and of pinkish-white colour. It is placed transversely across 
 the spine ; its larger end, or head, is embraced by the duodenum ; 
 its lesser end, or tail, is in contact with the spleen. The splenic 
 artery and vein run along the upper border of the gland, and 
 above it is the coeliac axis ; the lower border is in relation with 
 the transverse portion of the duodenum, from which it is sepa- 
 rated by the superior mesenteric vessels. Posteriorly, the pan- 
 creas rests upon the inferior vena cava, the left kidney, the left 
 supra-renal capsule, the commencement of the vena portse, the 
 aorta, the crura of the diaphragm, the superior mesenteric 
 vessels and the inferior mesenteric vein. Its duct runs from left 
 
394 KIDNEYS. 
 
 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 immediately beneath it, and others 
 from the gastro-duodenalis. 
 
 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 vense cavse hepaticse, and the branches of the coeliac 
 axis. These viscera, with the remainder 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 sympathetic nerve. 
 
 KIDNEYS AND The kidneys are situated in the lumbar region, 
 
 URETER, EELA- behind the peritoneum, one on each side of the 
 TIONS or. spine. They lie embedded in more or less fat, on 
 
 the quadratus lumborum, the psoas, and the crura of the diaphragm. 
 The right is somewhat the lower of the two. Surmounting each 
 is a small body, called the supra-renal capsule. The excretory 
 duct of the kidney, the 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. The right kidney is in 
 contact, above, with the under surface of the liver, and its upper 
 end reaches as high as the lower border of the eleventh rib ; the 
 left is in contact above with the spleen, and reaches to the level of 
 the upper border of the eleventh rib. 
 
 In front of the right kidney are the liver, the ascending colon, 
 the descending portion of the duodenum, and the colica dextra 
 artery ; in front of the left, the descending colon, part of the 
 spleen, the pancreas, and the colica sinistra artery. This explains 
 how it is that a renal abscess or calculus is sometimes evacuated by 
 the rectum. 
 
DIAPHRAGM. 
 
 395 
 
 The outer border of the kidney is convex, the inner concave, 
 and presents a notch, the hilus, for the entrance of the vessels 
 and duct, which have the following relations : anteriorly is the 
 renal vein, posteriorly is the ureter, the renal artery being between 
 them. 
 
 The kidneys and supra-renal capsules must be 
 removed and reserved for further examination. 
 
 The semilunar ganglia, two in number, are 
 situated one on each side of the creliac axis, in the 
 neighbourhood of the supra-renal bodies ; that on the right side 
 will be found lying under the vena cava inferior. Their filaments 
 
 FIG. 84. 
 
 DISSECTION. 
 
 SEMILTJNAB 
 GANGLIA.. 
 
 1. Aorta passing be- 
 
 tween the crura. 
 
 2. Opening for ceso- 
 
 phagus. 
 
 3. Opening for vena 
 
 cava. 
 
 4. Quadrat us lum- 
 
 borum. 
 
 5. Psoas magnua. 
 
 The dark arches 
 above the quad- 
 ratus and psoas 
 are the ' arcu- 
 ate ligaments.' 
 
 DIAPHRAGM. 
 
 DIAGRAM OF THE DIAPHBAGM, THE OPENINGS IN IT, AND THE PHRENIC ARTKRIE8. 
 
 are distributed to the supra-renal and renal plexuses, and to the 
 plexuses which surround the branches of the abdominal aorta. 
 Above, each ganglion receives the great splanchnic nerve (p. 147). 
 This is a partly muscular and partly tendinous 
 arch, so 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. On removing its peritoneal 
 covering, we observe a broad tendon in the centre, and that 
 muscular fibres converge to it from all sides (fig. 84). The dia- 
 phragm arises, 1. From the ensiform cartilage ; 2. From the inner 
 
396 DIAPHRAGM. 
 
 surfaces of the cartilages of the six lower ribs by as many 
 digitations, which correspond with those of the transversalis ; 
 3. From two thin tendinous arches, called, respectively, the liga- 
 menta 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) ; and 4. From the front of the bodies of the lumbar vertebrae 
 by two elongated bundles, called the crura of the diaphragm. 
 Both erura have tendinous origins ; the right crus is, however, a 
 little longer than the left ; the former arises from first, second, 
 and third lumbar vertebrae and their intervening cartilages, the 
 left does not descend so low by one vertebra. The inner fibres 
 of each crus decussate ; those of the right being the more anterior. 
 In their decussation the fibres separate the aortic from the oeso- 
 phageal openings. 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 white glistening surface, owing to the crossing of its 
 tendinous fibres ; and its shape may be 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, below 
 which it lies (p, 134), 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. 
 
 OPENINGS m There are three large openings in the diaphragm 
 
 THE DIAPHRAGM. f or h e transmission of the aorta, the oesophagus, 
 and the 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 observe 
 that the inner fibres of each cross each other in front of the aorta, 
 
DIAPHRAGM. 
 
 397 
 
 FIG. 85. 
 
 somewhat like the letter X.* Above the decussation, and a little 
 to the left of it, is the cesophageal opening ; this is oval and 
 entirely muscular, and transmits the oesophagus and the pneumo- 
 gastric nerves. The opening for the vena, cava (foramen 
 quadratuTn) is situated in 
 the highest part of the cen- 
 tral tendon, rather to the 
 right of the middle line. 
 Observe that the vein is 
 intimately connected to its 
 margin, and kept perma- 
 nently open. Lastly, there 
 pass through the crus, on 
 each side, the sympathetic 
 and the greater and lesser 
 splanchnic nerves. The 
 arch of the diaphragm, in 
 expiration, extends about 
 as high as the fifth rib on 
 
 the right side, and the sixth 
 
 ' (The dotted lines show the amount of descent 
 
 rib on the left. ^ contraction.) 
 
 The nerves of the dia- 
 phragm are the phrenic (p. 1 32), and the five or six lower inter- 
 costal nerves. The diaphragm also receives minute filaments 
 from the diaphragmatic plexus, which comes from the semilunar 
 ganglia. On its under surface on the right side, close to the 
 supra-renal capsule, the plexus joins some branches of the right 
 phrenic nerve, at which spot there is a small ganglion (ganglion 
 diaphragmaticum), from which filaments are given off to the 
 liver, vena cava and supra-renal capsule. It is absent on the left 
 side. Its blood-vessels are the two phrenic, derived from the 
 aorta, the internal mammary (p. 121), and the lower intercostal. 
 
 FUNCTION OF The diaphragm is the great muscle concerned 
 
 THE DIAPHRAGM. in inspiration. It may be said with Haller, that it 
 
 DIAPHRAGM FROM ITS UPPER SURFACE. 
 
 * This declaration is not always complete. But the right crus always crosses 
 more or less over the left, so that the crura are never strictly parallel. 
 
398 DIAPHKAGM. 
 
 is * musculus post cor nobilissimus.' During inspiration the mus- 
 cular sides of the diaphragm contract, and become less arched 
 (as shown by the dotted line in fig. 85) ; 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 sinking and 
 rising of the diaphragm constitutes a chief part of the mechanism 
 of breathing. But the diaphragm conduces to the performance of 
 many other functions. Acting in concert with the abdominal 
 muscles, it assists in the expulsion of the faeces and the urine, also 
 in parturition and in vomiting : for in all these operations we first 
 take in a deep breath, that the diaphragm may be in a state of 
 contraction, 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 
 concerned in laughing, sneezing, coughing, hiccough. 
 
 ^ The muscles and nerves at the back of the 
 
 DISSECTION. 
 
 abdomen must be carefully cleaned ; also, the 
 abdominal aorta, and vena cava inferior in front of the spine, with- 
 out injuring the sympathetic nerves, situated on each side of the 
 bodies of the vertebras. 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 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. 
 
 M This long muscle arises by five muscular fasciculi 
 
 from the transverse processes of all the lumbar 
 vertebrae, also from the bodies of the last dorsal, and all the 
 lumbar vertebrae and their intervening fibre-cartilages ; but only 
 from the projecting borders of the bodies, not from the cen- 
 tral grooved part : here the fibres arise from tendinous arches 
 
PSOAS AND ILIACUS. 399 
 
 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. In front, the psoas has in relation 
 with it the ligamentum arcuatum internum, the external iliac 
 artery, the kidney and the ureter, the spermatic vessels, the genito- 
 crural nerve and the vas deferens ; behind it, are the ilium, the 
 quadratus lumborum, the lumbar plexus of nerves, and the obturator 
 nerve which, lower down, runs along the inner border of the muscle. 
 Towards its insertion, the tendon of the psoas lies between the 
 iliacus and the pectineus. 
 
 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 
 more frequently in old ones, in consequence of wear and tear, 
 this bursa communicates with the hip-joint. The fact is im- 
 portant ; for it explains how a psoas abscess sometimes makes its 
 way into the hip-joint : a result frequently fatal. 
 
 PSOAS PAKVUS Once in about eight or ten subjects there is a 
 
 small muscle called the psoas parvus. It arises 
 from the bodies of the last dorsal and the first lumbar vertebrae, and 
 the intervening fibro-cartilage ; thence descending in front and to 
 the inner side of the psoas magnus, it ends in a long flat tendon, 
 which spreads out, and is inserted into the linea ilio-pectinea. 
 
 ILIACUS INTBRNUS This muscle occupies the iliac fossa, and is 
 AND ILIAC FASCIA, covered by the iliac fascia. This iliac fascia is 
 attached to the crest of the ilium, and indirectly to the brim of the 
 pelvis through its connection with the sheath of the psoas. Its 
 most important attachment is to the outer half of the crural arch ; 
 here it is directly continuous with the fascia transversalis (p. 365), 
 so that, together, they present an effectual barrier to the escape of 
 intestine beneath this part of the arch.* The external iliac artery 
 
 * The iliac fossae are liable to be the seat of suppuration, and the course which 
 the pus takes depends upon its position with regard to the iliac fascia. If the 
 pus be seated in the loose cellular tissue between the peritoneum and the fascia, it 
 
400 PSOAS AND ILIACUS. 
 
 and vein lie in front of the fascia, while the anterior crural nerve 
 is behind it. 
 
 The iliacus internus arises from the iliac fossa, from the ilio- 
 lumbar ligament,* and from the capsule of the hip-joint. The 
 fibres converge beneath the crural arch, and are inserted mainly 
 into the outer side of the tendon of the psoas, and partly into the 
 triangular surface of the femur, below and anterior to the lesser 
 trochanter. Thus the two muscles, so far as their action goes, 
 may be considered as one, and are sometimes called the ilio- 
 psoas. 
 
 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. If the fixed point be at the spine, then the 
 muscle flexes and rotates the femur outwards. It is this action 
 which often occasions so much displacement in fractures of the 
 upper third of the femur. 
 
 Q0ADBATus This musc l e extends from the crest of the ilium 
 
 LUMBORUM AND to the last rib, and is contained in a sheath formed 
 ITS SHEATH. f or it by the aponeurotic origin of the transver- 
 
 salis (p. 361). The anterior layer of its sheath is attached to the 
 roots of the transverse processes of the lumbar vertebrae, and the 
 posterior layer to their summits. The muscle, broader below than 
 above, arises from the ilio-lumbar ligament and from the crest of 
 the ilium for two inches external to it. It is inserted into the 
 last rib, and by tendinous slips into the transverse processes of 
 the upper four lumbar vertebrae. Besides the preceding, a few 
 fibres of the muscle arise from the transverse processes of the 
 third, fourth and fifth lumbar vertebrae, and, running up in front 
 of the others, are inserted in common with them. The principal 
 use of the muscle is to steady the spine ; it also steadies the last 
 
 usually advances just above the crest of the ilium, or towards the groin through 
 the inguinal canal ; but, if seated beneath the fascia, the matter usually makes its 
 way under the crural arch towards the upper and outer part of the thigh. 
 
 * This ligament extends from the transverse process of the last lumbar vertebra 
 to the ilium. 
 
ABDOMINAL AORTA. 401 
 
 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 pro- 
 cesses : 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 lymphatic glands extends along 
 the brim of the pelvis and the bodies of the lumbar vertebrae, 
 following 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 
 receptacuLum chyli, or beginning of the thoracic duct (p. 142). 
 This is usually found on the right of the aorta, close to the second 
 lumbar vertebra. 
 
 EELATIONS OF The aorta enters the abdomen between the 
 
 THE ABDOMINAL crura of the diaphragm in front of the last dorsal 
 AosTA< vertebra, and descends a little to the left side of 
 
 the front of the spine, as low as the middle of the fourth lumbar 
 vertebra, where it divides into the two common iliac arteries. The 
 division is about the level of the highest point of the crest of 
 the ilium, and just below the left side of the umbilicus. The 
 aorta is crossed in front by the splenic vein, the pancreas, the trans- 
 verse portion of the duodenum, the left renal vein, the mesentery ; 
 and it has also in front of it a chain of lymphatic glands. To the 
 right side of it lie the vena cava inferior, the thoracic duct, the 
 vena azygos, and the right eras of the diaphragm. To the left 
 side of it is the left crus, and on each side are the sympathetic 
 nerves. 
 
 * 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 between 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. 
 
 D D 
 
402 BRANCHES OF THE ABDOMINAL AORTA. 
 
 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. 384.) 
 
 PHRENIC These arteries supply the under surface of the 
 
 AKTERIES. diaphragm, and arise separately, or by a common 
 
 trunk, from the aorta after its passage under the pillars 
 (p. 396). The right phrenic passes outwards, behind the vena 
 cava, the left behind the oasophagus ; each ascends, lying on its 
 corresponding crus,as far as the central tendon, where each divides 
 into two branches : one-which passes transversely across the tendon 
 to the side of r the diaphragm ; the other, which seems to be the 
 continuation of the artery, runs forwards to the anterior part of 
 the muscle. Their first 'branches are to the supra-renal capsules ; 
 then the right gives off a small branch to the vena cava, the left, 
 one to the ossophagus. 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, if not in the vena cava. 
 SUPRA-RENAL The supra-renal or consular arteries are two 
 
 ARTERIES. very small branches, given >off from the aorta 
 
 opposite to the superior mesenteric artery; -each runs upon the 
 crus of the diaphragm, the right behind the inferior cava, and is 
 distributed to the supra-renal body, inosculating with branches 
 from the phrenic and renal arteries. The right capsular vein ter- 
 minates in the inferior vena cava, the left in the left renal. 
 
 KENAL ARTE- ''The renal arteries arise from the aorta at right 
 HIES AND VEINS. angles, and run transversely to the kidneys. Both 
 are covered by their corresponding veins. The right is longer and 
 rather lower 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 a single trunk, but by several branches, corre- 
 sponding to the original lobes of the organ. The renal veins 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 
 also receives the spermatic, capsular, and sometimes the phrenic 
 veins of its own side. 
 
BRANCHES OF THE ABDOMINAL AORTA. 403 
 
 SPERMATIC The spermatic arteries, two in number, arise 
 
 ARTERIES AND from the front of the aorta, a little below the 
 VEINS - renal. Each runs down upon the psoas, crossing 
 
 over the ureter and over the front of the external iliac artery im- 
 mediately above the crural arch. Each then passes through the 
 internal abdominal ring and inguinal canal, with the other con- 
 stituents of the spermatic cord to the testicle. Each artery is 
 accompanied by two very tortuous veins, which unite before they 
 empty themselves, on the right side into the vena cava, on the 
 left, into the renal vein. In the female, the ovarian arteries do 
 not leave the abdomen, but pass, between the layers of the broad 
 ligaments, to the ovaries. 
 
 LUMBAR There are five of these arteries on either side : 
 
 ARTERIES AND four arise from the aorta, the fifth comes from the 
 BRANCHES. arteria sacra media. They are analogous to the 
 
 intercostal arteries on a small scale. They proceed outwards over 
 the bodies of the vertebrae, beneath the arch formed by the psoas 
 muscle, towards the intervertebral foramina, and then, like the 
 intercostals, divide into dorsal and abdominal branches. The two 
 upper lumbar arteries pass beneath the crura of the diaphragm, 
 those on the right side being also behind the vena cava. 
 
 The dorsal branches pass between the transverse processes 
 of the vertebrae, accompanied by the posterior branches of the cor- 
 responding nerves, and are of a size proportionate to the large 
 development of the muscles of the back which they supply. They 
 also send spinal branches, which enter the spinal canal through 
 the intervertebral foramina; some of these are distributed to the 
 anterior part of the cauda equina, and others to the bodies of the 
 lumbar vertebrae, forming a series of arches behind them. 
 
 The abdominal branches all run outwards behind the quadra- 
 tus lumborum, except the last, which usually runs in front. After 
 supplying the quadratus and psoas, they pass forwards between the 
 abdominal muscles and supply the walls of the abdomen.* They 
 
 * Just as the thoracic intercostals, by communicating with the internal mammary, 
 form an arterial ring round the chest, so do the lumbar, by communicating with 
 the epigastric, form a similar, though less perfect, ring round the walls of the 
 abdomen. 
 
 D n 2 
 
404 VENA CAVA COMMON ILIAC AETEEIES. 
 
 anastomose, laterally, with the ilio-lumbar and circumflex iliac 
 arteries, and, in front, with the internal mammary and epigastric 
 arteries. 
 
 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. 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. In animals it is the artery of the 
 tail. 
 
 VENA CAVA The vena cava inferior is formed by the junction 
 
 INFERIOR. of the two common iliac veins, a little to the right 
 
 side of the fifth lumbar vertebra. 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 inclines a little to the 
 right, separated from the aorta by the right crus, 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, the 
 liver, and the right spermatic artery ; behind it are the right 
 renal artery, the right lumbar arteries, and 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. 
 
 COMMON ILIAC The aorta divides, in front of the fourth lumbar 
 
 ARTERIES AND vertebra, into two great branches, termed the com- 
 VEINS - mon iliac arteries. They diverge at an acute angle, 
 
 and, after a course of about two inches, each divides over the sacro- 
 iliac symphysis, into the external and internal iliac. They lie 
 upon the bodies of the fourth and fifth lumbar vertebrae. They 
 are covered by peritoneum, and crossed, at or near their division, by 
 the ureters. They are also crossed by branches of the sympathetic 
 on their way to the hypogastric plexus. So far, then, the relations 
 
EXTERNAL ILIAC ARTERY. 405 
 
 of both common iliac arteries are similar. But each has its special 
 relations as follows : 
 
 The special relations of the right common iliac are, that it lies, 
 at its commencement, close to the left of the inferior vena cava ; 
 and that it subsequently crosses over both the common iliac veins. 
 
 The special relations of the left common iliac are, that it has, 
 in front of it, the end of the sigmoid flexure of the colon and the 
 inferior mesenteric vessels ; and, to its right side, the common iliac 
 vein, which gradually gets more behind it towards the sacro-iliae 
 symphysis. 
 
 The relations of these arteries with regard to their corre- 
 sponding veins are, practically, important in reference to the ope- 
 ration of tying them. This operation is. obviously, easier on the 
 left side than the right.* 
 
 If the common iliac artery were ligatured, the collateral cir- 
 culation would be maintained through the following vessels-: by 
 the internal mammary anastomosing with the deep epigastric a. ; 
 by the lumbar arteries with the circumflex iliac and the ilio- 
 lumbar a. ; by the lumbar with the gluteal ; by the middle sacral 
 with the lateral sacral a. ; by the spermatic with the deferential, 
 cremasteric, external pudic and superficial perineal arteries ; by 
 the superior haemorrhoidai with the middle and inferior haemor- 
 rhoidal a. ; by the lower intercostals with the epigastric a. (super- 
 ficial and deep) ; and by the middle and the inferior haemorrhoidai, 
 the pudic and its branches, and the vesical arteries communica- 
 ting in the middle line with the corresponding branches of the 
 opposite side. 
 
 EXTERNAL The external iliac artery passes along the brim 
 
 ILIAC AKTERT. o f the pelvis, first on the inner side, and then in 
 
 * The length of the common iliac, artery is apt to vary in different persons. We 
 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, its length in any 
 given instance, as 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. 
 The left is usually described as rather longer than the right ; but, from the examina- 
 tion of 100 bodies, our conclusion is that their average length is the same. 
 
406 EXTERNAL ILIAC AETEET. 
 
 front of the psoas. Lower down it passes under the crural arch, 
 midway between the anterior superior spine of the ilium and the 
 symphysis pubis, and takes the name of femoral. The artery has 
 in front of it the peritoneum, and intestine ; and, just above 
 Poupart's ligament, the deep circumflexa ilii vein, the spermatic 
 vessels, and the vas deferens. On its inner side, and on a plane 
 somewhat posterior, is the corresponding vein. The iliac fascia 
 lies behind the vessels, but a thin layer of fascia derived from it 
 is continued over them. In front of the artery are a chain of 
 lymphatic glands. 
 
 The branches given off by this artery are : 
 The deep epigastric, already described (p. 366). 
 The deep circumflexa ilii, which arises from the outer side of 
 the artery, just above the crural arch, and running towards the 
 anterior superior spine of the ilium in a sheath formed by the 
 fascia iliaca, subsequently perforates the transversalis muscle.* In 
 the dissection of the abdominal muscles (p. 367), the continuation 
 of it was seen skirting the crest of the ilium between the internal 
 oblique and the transversalis, and sending a branch upwards be- 
 tween these muscles for their supply. The main trunk, much 
 reduced in size, inosculates with the ilio-lumbar derived from the 
 internal iliac. 
 
 LIGATUKE OF ^^ & best way of tying the external iliac is to 
 
 THE EXTERNAL make a curved incision at the lower part of the 
 ILIAC - abdomen, beginning a little above the middle of 
 
 the crural arch, and ending about an inch to the inner side of 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 with the spermatic vessels 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. Remember that the vein is closely 
 connected to its inner side,f that the genito-crural nerve is not 
 
 * The course of this artery should be borne in mind in opening iliac abscesses, 
 f This relative position of the vessels does not always exist. In old subjects, 
 less frequently in adults, it is sometimes found that the external iliac artery runs very 
 
SYMPATHETIC IN THE ABDOMEN. 
 
 far off, and that -the circumflex iliac vein crosses the artery just 
 above Poupart's ligament. 
 
 After ligature of the artery the collateral circulation would be 
 maintained by anastomoses between the internal mammary and the 
 deep-epigastric; between the lumbar arteries and, the circumflex 
 iliac; between the pubic branch of the obturator* and the branch 
 of the epigastric; between the gluteal.and the, internal .and 
 external circumflex; between the. sciatic and the first perforating 
 and the internal circumflex; between the obturator, and the in- 
 ternal circumflex; between the spermatic, the deferential, and the 
 cremasteric and the external pudic; between the lower intercostals 
 and the lumbar arteries and the epigastric artery. 
 
 SYMPATHETIC The general plan upon which the sympathetic 
 
 NERVE. nerve is arranged has been noticed in the dis- 
 
 section of -the neck' (p. ..1 14). 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 vertebrae, along the inner 
 border of the psoas. The nerve has an oval ganglion opposite each 
 lumbar vertebra, so that there are five on each side. These ganglia 
 are connected by small filaments, and each ganglion receives two 
 branches from the corresponding spinal nerve, as in the chest. 
 
 SOLAR PLEXUS The solar plexus is situated in front of the 
 AND THE SEMI- aorta and surrounds the coeliac axis in a dense 
 LUNAR GANGLIA. network of nerve-filaments, on which are several 
 
 tortuously, instead of nearly straight, along the brim of the pelvis. But the vein dees 
 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 
 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 tha 
 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.' 
 
408 LUMBAR PLEXUS. 
 
 ganglia. It receives the splanchnic nerves, and some branches 
 from the pneumogastric nerves ; and it gives off filaments which 
 surround the various branches of the abdominal aorta, the plexuses 
 thus formed taking the name of the arteries they accompany. 
 
 The semilunar ganglia are situated, one on each side of the 
 coeliac axis, and internal to the supra-renal capsules. These ganglia 
 have been described (p. 395). 
 
 The plexuses connected with these nervous centres are, the dia- 
 phragmatic, the superior mesenteric, the supra-renal, the renal, the 
 spermatic, the coronary hepatic and splenic, the aortic, and the inferior 
 mesenteric. 
 
 HYPOGASTRIC The hypogastric plexus is situated between the 
 
 PLEXUS. common iliac arteries, on the last lumbar vertebrae 
 
 and the sacrum. It consists of an intricate interlacement of 
 sympathetic filaments, which pass down into the pelvis, for the 
 supply of the pelvic viscera. Although this plexus is so in- 
 tricate, it presents no distinct ganglia. As it passes down it 
 receives branches from some of the spinal nerves, but mainly 
 from the third and fourth sacral nerves. From this large plexus 
 are derived secondary plexuses, which ramify around branches of 
 the internal iliac artery : thus there are, the inferior hsemorrhoidal 
 plexus, the vesical, the uterine, the ovarian, the prostatic, and 
 the vaginal ; all of which send filaments which accompany the 
 smallest branches of the arteries. 
 
 LUMBAR The lumbar plexus is formed by the union 
 
 PLEXUS OF of the anterior branches of the four upper lum- 
 
 NERVES. ^ nerves> ^he fifth does not enter into the 
 
 formation of this plexus, but joins the sacral plexus under the 
 name of the lumbo-sacral cord. The plexus lies over the transverse 
 processes of the corresponding vertebras, embedded in the substance 
 of the psoas, so that this muscle must be dissected away before the 
 plexus can be seen. Like : the brachial plexus, the nerves com- 
 posing it successively increase* in .size. from above. Its branches 
 are five in number, and arise imthe following order (fig. 86). 
 
 a. The first lumbar '\nerve generally divides into two branches ; 
 
LUMBAR PLEXUS. 
 
 409 
 
 the upper being 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 forwards 
 to the crest of the ilium, where it pierces the transversalis, and 
 divides into its two terminal branches the iliac branch, which 
 supplies the skin over the glutseal region, behind the last dorsal 
 nerve, and the hypogastric branch, which runs forward between the 
 transversalis and internal oblique, and then perforates the aponeu- 
 
 - a. Hio-bypogastric n. 
 6. Hio-inguinal n. 
 c.^External cutaneousn. 
 
 d. Anterior crural n. 
 
 e. Crural branch of genito- 
 
 crural n. 
 /. Obturator n. 
 y. Genital branch of genito- 
 
 cruraln. 
 h. Lumbo-sacral n. 
 
 1 . First lumbar n. 
 
 2. Second 
 
 3. Third 
 
 4. Fourth ,, 
 -5. Fifth 
 
 PLAN OF THE LUMBAR PLEXUS AND BRANCHES. 
 
 rosis of the external oblique to supply the skin. The ilio-inguinal, 
 the smaller, 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. 
 
 6. The genito-crural nerve is small, and 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 
 
410 LUMBAR PLEXUS. 
 
 arch divides into the genital branch ((7), which runs along 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. 
 
 c. 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 
 th e anterior crural, nearer the psoas muscle. 
 
 d. The anterior crural (d), the largest and most important 
 branch, is formed by the union x>f the third and fourth lumbar 
 nerves, sometimes receiving a small 'branch from the second. It 
 descends in a groove between the psoas and the iliacus behind the 
 fascia iliaca, supplies both these muscles, and then, passing under 
 the crural arch to the outer side of the femoral artery, is finally 
 distributed to the extensor muscles of the knee, to the sartorius 
 and pectineus, and the skin of the thigh and leg. 
 
 e. The obturator nerve (/) is next in size to the anterior crural. 
 It proceeds from the third and fourth lumbar nerves, descends 
 behind the psoas muscle, and then, getting to its inner border it 
 runs along the brim of tfofe pelvis to the obturator foramen, through 
 the upper part of which it passes to the adductor muscles of the 
 thigh. 
 
 /. The accessory obturator nerve, by no means a constant 
 branch, is derived from the third and fourth lumbar nerves. It 
 descends over the horizontal ramus of the pubes, supplies the pec- 
 tineus and gives off a small branch to the hip joint. 
 
 Postponing the minute anatomy of the abdominal viscera, 
 begin the examination of the contents of the pelvis. 
 
THE PELVIS AND ITS FUNCTIONS. 411 
 
 DISSECTION OF THE PELVIC VISCERA. 
 
 The functions 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 an 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 tbigh*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 alee of the iliac bones are more expanded. The 
 projection of the sacrum is less perceptible^ and consequently 
 the brim is more circular. 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 
 the pelvis corresponds with a line drawn from the anus to the 
 umbilicus.* 
 
 * 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 
 
412 RECTO- VESICAL POUCH. 
 
 CONTENTS OF The male pelvis contains the last part of the 
 
 THE MALE PELTIS. intestinal canal, named the rectum, the bladder 
 with the prostate gland at the neck, and the vesiculse seminales. 
 If the bladder be empty, some of the small intestine will be in 
 the pelvis ; not so if the bladder be distended. 
 
 COURSE OF The rectum enters the pelvis on the left side 
 
 THE EECTUM. of the sacrum, and, after describing a curve cor- 
 
 responding 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 meso- 
 rectum : between the layers of this fold, the superior hsemor- 
 rhoidal vessels, the continuation of the inferior mesenteric, with 
 nerves and lymphatics, runs to the bowel. 
 
 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 arrangement cannot be ascertained 
 during life, they should make us cautious in the introduction of 
 bougies.* 
 
 KECTO-VESICAL Whilst the parts are still undisturbed, intro- 
 POUCH. duce the finger into -the recto^vesicdl peri- 
 
 toneal pouch (fig. 8). 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, 
 the bottom of this pouch is about one inch distant from the base 
 of the prostate .gland :-f- 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 
 
 children, its capacity is small ; and the viscera, which subsequently belong to it, are 
 situated in the abdomen. 
 
 * In old age the rectum has sometimes a zigzag appearance immediately above 
 the anus. These lateral inclinations are probably produced by the enormous disten- 
 sions to which the bowel has been occasionally subjected. 
 
 f The bottom of the pouch is from three to four inches distant from the anus. 
 
KECTO-VESICAL POUCH. 
 
 413 
 
 years, been revived, and with great success.* It is easily done, 
 and not attended with risk, provided all the parts be in their 
 regular position. But this is not always the case. It sometimes 
 happens that the peritoneal 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 impossible to tap 
 the bladder from the rectum without going through the peri- 
 toneum. In children the peritoneum comes down lower than it 
 does in the adult, because the bladder in the child is not a pelvic 
 viscus. 
 
 FIG. 87. 
 
 Symphysis pubis 
 
 Corpus cavernosnm 
 penis 
 
 Peritoneum in dot- 
 ted outline. 
 
 Ureter. 
 
 Vas deferens. 
 Vesicula seminalis. 
 
 Glans penis . . . 
 
 Corpus spongiosum 
 urethras . . . . 
 
 Bulb of corp. spon- 
 giosum . . . . 
 
 Cowper's gland with 
 duct 
 
 Membranous part 
 of urethra sur- 
 rounded by com- 
 pressor muscle. 
 
 Prostate gland 
 
 DIAGEAM OF THE RELATIVE POSITION OF THE PELVIC VISCERA. 
 
 The recto- vesical pouch is permanent. But there is another 
 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. The 
 bladder soon fills the pelvis, and then, rising into the abdomen, 
 occasions the pouch between it and the abdominal wall. At 
 first, the pouch is shallow, but it gradually deepens as the bladder 
 
 * See a paper in the ' Med. Chir. Trans.' voL xxxv-by Mr. Cock. 
 
414 DISSECTION OP THE MALE PERINEUM. 
 
 rises. 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 symphysis pubis (fig. 87). Within this distance from the 
 symphysis, the bladder may be tapped in the linea alba, with- 
 out 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 ex- 
 amine the osseous and ligamentous boundaries of the lower aper- 
 ture of 1She pelvis. Looking at the male 
 pelvis (with the ligaments -preserved), 
 we observe 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 ; behind, by the coccyx and the 
 great saero-ischiatic ligaments. 
 
 This space, for convenience of de- 
 scription, is divided into two by a line 
 DIAGRAM OF THE FRAMEWORK drawn from one tuber ischii to the other. 
 OF THE PERINEUM. Tfae anterior f orms a Dearly equilateral 
 
 triangle, of wMch the sides are from three to three and a-half 
 inches long 4 and since it transmits the urethra, it is called the 
 urethral division of the perineum. The posterior, containing the 
 anus, is called the anal division (fig. 88, 2).* 
 
 The subject should 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. A 
 
 * The dimensions of the lower outlet of the pelvis are apt to vary in different 
 subjects, and the lithotomist must modify 'his incisions accordingly. 
 
DISSECTION OF THE MALE PEKINEUM. 415 
 
 central ridge, named the rapJie, 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, one on 
 each side, marking the ischio-rectal fossce, which are found imme- 
 diately beneath the skin, filled with more or less fat. In the lateral 
 operation of lithotomy, the incision should commence at a point 
 midway between the anus and the posterior fold of the scrotum, 
 close to the left side of the raphe ; it should be carried downwards 
 and outwards 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 
 delicate, 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 provided with numerous minute 
 glands,* 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 defsecation becomes very painful. 
 
 The skin should be reflected, by making 1 an 
 
 DISSECTION 
 
 incision along the raphe, round the margin of the 
 anus to the coccyx. Two others must be made on each side at 
 right 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 
 SUBCUTANEOUS outwards. In reflecting the skin, notice the .charac- 
 TISSUE. ters of the subcutaneous structure.! Its characters 
 
 * 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 anus, but also in the subcutaneous 
 tissue of the perineum, a fact for the demonstration of which we are indebted to 
 the late Professor Quekett. They are large enough to be seen with the naked eye. 
 
 t The probable thickness of this subcutaneous tissue is a point whieh 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 pus from the 
 ischio-rectal fossa. 
 
416 DISSECTION OP THE MALE PERINEUM. 
 
 alter in adaptation to the exigencies of each part. On the scro- 
 tum the fat constituent of the tissue is entirely absent ; while 
 the connective tissue element is most abundant, and during life 
 elastic and contractile. But, towards the deeper part of the anus, 
 
 FAT IN ISCHIO- the fat accumulates more and more, and on either 
 RECTAL FOSSJK. s {^ e o f the rectum it is found in the shape of large 
 masses, filling up what would otherwise be two deep hollows in this 
 situation namely, the ischio-rectal fossce. These fossse are tri- 
 angular, 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 much deeper posteriorly than 
 in front. This accumulation of fat on each side of the anus, 
 permits the easy distension and contraction of the lower end of 
 the bowel during and after the passage of the faeces. Over the 
 tuberosities of the ischia are 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 external sphincter ani must now be cleaned ; 
 care being taken not to remove any of its fibres ; 
 which are intimately connected with the skin. Posteriorly, the 
 lower border of the glutens maximus must be displayed, and the 
 vessels and nerves crossing the perineum, towards the anus, care- 
 fully dissected. 
 
 EXTERNAL The external sphincter of the anus is elliptical, 
 
 SPHINCTER ANI. an( j arises from the point of the coccyx, and 
 the ano-coccygeal ligament. The muscular fibres surround the 
 anus, and are inserted in a pointed manner in the tendinous centre 
 of the perineum (p. 419). It is called the external sphincter, to 
 
DISSECTION OP THE MALE PEEINEUM. 41 7 
 
 distinguish it from a deeper and more powerful band of muscular 
 fibres which s,urrounds the last inch or more of the rectum, and is 
 situated next to the mucous membrane. 
 
 CUTANEOUS ^he cutaneous vessels and nerves of the peri- 
 
 VESSELS AND neum come from the internal pudic artery and 
 
 NEBVES. nerve, and chiefly from that branch of it called the 
 
 superficialis perinei. This will be traced presently. 
 
 The external or inferior hcemorrhoidal arteries, cross trans- 
 versely through the ischio-rectal fossa, from the ramus of the 
 ischium towards the anus. They come from the pudic (which may 
 be felt on the inner side of the ischium), and running inwards, 
 divide into numerous branches, which 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. 
 
 The fourth sacral nerve emerges through the coccygeus close 
 to the tip of the coccyx, and supplies the skin of the perineum 
 between this bone and the anus. 
 
 The inferior pudendal nerve comes through the muscular 
 fascia of the thigh, a little above the tuber ischii, and ascends, 
 dividing into filaments, which supply the front and outer part of 
 the scrotum and perineum. It is a branch of the lesser ischiatic 
 nerve, and communicates in front with the posterior branch of the 
 superficial perineal nerve. 
 
 SUPERFICIAL The subcutaneous fascia of the perineum is 
 
 FASCIA OF THE composed of a superficial and a deep layer. The 
 PERINETJM. superficial layer contains more or less fat, and is 
 
 continuous with that of the scrotum, the thighs, and the posterior 
 part of the perineum. The deeper layer is best demonstrated by 
 blowing air beneath it with a blow-pipe ; its connections are as 
 follows : It is attached on each side to the anterior lip of the 
 ramus of the pubes and ischium ; traced forwards, it is directly 
 continuous with the tunica dartos of the scrotum ; traced back- 
 wards, at the base of the urethral triangle, it is reflected beneath 
 the transversus perinei muscle, and joins the deep perineal fascia 
 or triangular ligament. These connections explain why urine, 
 
 E E 
 
418 DISSECTION OF THE MALE PERINEUM. 
 
 effused into the perineum, does not make its way into the ischio- 
 rectal fossae, or down the thighs, but passes readily into the scrotum 
 and penis. 
 
 Remove the fascia to see the muscles which 
 
 DISSECTION* 
 
 cover the bulb of the urethra and the crura of the 
 
 penis. The bulb of the urethra lies in the middle of the peri- 
 neum, and is covered by a strong muscle, called accelerator urinae. 
 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 peri- 
 neum. 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 perineum. 
 
 Thus the muscles of the perineum describe on each side a 
 triangle, of which the sides are formed by the accelerator urinse 
 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 the inferior pudendal nerve, a branch of the 
 lesser ischiatic. 
 
 SUPERFICIAL The superficial perineal artery comes from 
 
 PERINEAL VESSELS the internal pudic as it runs up the inner side of 
 AND NERVES. foe tuber ischii. 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, passes up the perineal triangle, distributing branches to all 
 the muscles, and is finally lost on the scrotum. The only 
 named branch is called transversalis perinei (fig. 89). This 
 is given off near the base of the triangle, and runs with the 
 transversus perinei muscle towards the central point of the 
 perineum, where it anastomoses with its fellow. It is necessarily 
 divided in the first incision in lithotomy, and deserves attention, 
 because it is sometimes of considerable size. 
 
 The artery is accompanied by two veins, which are frequently 
 dilated and tortuous, especially in diseased conditions of the scrotum. 
 
DISSECTION OF THE MALE PERINEUM. 
 
 419 
 
 The nerves, two in number, are derived from the internal pudic, 
 follow the course of their corresponding arteries, and give off 
 similar branches. They not only supply the skin of the perineum 
 and scrotum, but each of the perineal muscles. 
 
 FIG, 89. 
 
 Triangular liga- 
 ment . . . 
 
 Tendinous centre 
 of the perineum 
 
 Transversus peri- 
 nei . 
 
 I?chio-rectal fossa 
 
 Inferior puden- 
 da! n. 
 
 Transversalis 
 perinei a. 
 
 Snperflcialis 
 
 perinei a. 
 External hee- 
 
 morrhoidal a. 
 
 MUSCLES, "WITH SUPERFICIAL VESSELS AND NBKVES, OF THE PERINEUM. 
 
 The inferior pudendal nerve, a branch of the lesser ischiatic, 
 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 front of the perineum and scrotum. 
 
 E K 2 
 
420 DISSECTION OP THE MALE PERINEUM. 
 
 ACCELERATOR This muscle embraces the bulb of the urethra. 
 
 UJUN^E. It arises from a fibrous median raphe beneath the 
 
 bulb, and from the tendinous centre of the perineum. Starting 
 from this origin, the fibres diverge, and are inserted as follows : 
 The upper ones proceed on either side round the corpus caver- 
 nosum penis, like the branches of the letter V, and are fixed on its 
 dorsal surface ; the middle completely embrace the bulb, like a 
 ring, and meet in an aponeurosis on the upper surface of the 
 urethra ; the lower are fixed to the anterior surface of the deep 
 perineal fascia, often called the triangular ligament (fig. 90).* 
 
 FIG. 90. 
 
 Corpus cavernosum . . . 
 Corpus spongiosum . . . 
 
 Upper fibres 
 
 Middle fibres 
 
 Lower fibres 
 
 Tendinous centre of peri 
 iieum 
 
 DIAGRAM TO SHOW THE ACCELERATOR URIN.ZE IN PROFILE. 
 
 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 
 turning back each half, its insertion, as above described, can be 
 clearly made out.f 
 
 EKECTOB This muscle is moulded upon the eras of the 
 
 PENIS, penis. It arises from the inner surface of the 
 
 tuber ischii ; the fibres ascend, completely covering the crus, and 
 
 * This muscle is called also the ejaculator urina or the bulbo-cavrenosus. 
 j- According to Hobelt, the dorsal insertion of the upper fibres throws a prolonga- 
 tion over the dorsal vessels of the penis. 
 
DISSECTION OF THE MALE PERINEUM. 
 
 421 
 
 terminate on a strong aponeurosis, which is inserted into the ex- 
 ternal and inferior aspect of the crus. The action of this muscle 
 is to compress the root of the penis, and so to contribute to the 
 erection of the organ.* 
 
 FIG. 91. 
 
 Crus penis 
 
 Crus penis with its ar- 
 tery cut through . . 
 
 Ramus of the ptibes 
 
 Artery of the bulb . 
 Cowper's gland . . 
 Pudic artery . . . 
 
 Tuber ischii . 
 
 DIAGRAM TO SHOW THE TRIANGULAR LIGAMENT OF THE URBTHBA 
 OR DEEP PER1NEAL FASCIA. 
 
 TRANSYERSCS 
 PERINEI. 
 
 This muscle is of insignificant size, and some- 
 times absent. It arises from the inner aspect of 
 the tuber ischii, and proceeds forwards and inwards towards the 
 * This muscle is sometimes called the ischio-cavmiosus. 
 
422 DISSECTION OF THE MALE PERINEUM. 
 
 central point of the perineum, where it is blended with the fibres 
 of the accelerator urinse. This muscle with its artery is divided 
 in lithotomy. 
 
 The deep transversus perinei is a small muscle occasionally 
 present ; it arises more deeply from the pubic arch than the super- 
 ficial muscle, and passes inwards behind the bulb, to the central 
 tendon. 
 
 The next stage of the dissection consists in reflecting and re- 
 moving the accelerator urinse from the bulb of the urethra, the 
 erectores penis with the crura 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. 
 
 TRIANGULAR Understand that the triangular ligament of the 
 
 LIGAMENT OF THE urethra and the deep perineal fascia are synony- 
 
 URETHRA. moUS terms. 
 
 The triangular ligament, shown in fig. 91, is a strong fibrous 
 membrane stretched across the pubic arch. It is about an inch 
 and a half long, with the base directed backwards. It consists 
 of two layers, an anterior and a posterior. The anterior 
 layer is firmly attached on each side 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 
 ligament ; inferiorly, it does not present a free border, but is 
 connected to the tendinous centre of the perineum, and is con- 
 tinuous with the deep layer of the superficial perineal fascia which 
 curves backwards under the transversus perinei muscle (p. 417). 
 
 The anterior layer of the triangular ligament is perforated 
 about one inch below the symphysis pubis, for the membranous 
 part of the urethra. The aperture through which the urethra 
 passes does not present a distinct edge, because the ligament is 
 prolonged forwards over .the bulb, and serves to keep it in 
 position. 
 
 The posterior layer cannot at present be seen. It belongs, 
 strictly speaking, to the pelvic fascia, and slopes somewhat back- 
 wards from the anterior layer so as to leave an interval between 
 them in which are found structures which will be presently described. 
 
DISSECTION OF THE MALE PERINEUM. 
 
 423 
 
 POINTS OF SUB- The triangular ligament is very important 
 GICAL INTEREST. surgically for these reasons : 
 
 1. Here we meet with difficulty in introducing a catheter, 
 unless we can hit off the right track through the ligament. The 
 
 FIG. 92. 
 
 Compressor urethras . . 
 
 Membranous part of the 
 urethra surrounded by 
 its compressor muscle. 
 
 Prostate gland .... 
 
 Anterior fibres of the le- 
 vatorani . 
 
 DIAGRAM OP THE PARTS BEHIND THE ANTERIOR LATER OF THE TRIANGULAR 
 LIGAMENT OF THE URETHRA. 
 
 (The anterior fibres of the levator ani are hooked down to show part of the prostate ; 
 the rest is tracked by a dotted line.) 
 
 soft and spongy tissue of the bulbous part of the urethra in front 
 of the ligament readily gives way, if force be used, and a false 
 passage results. 
 
424 DISSECTION OF THE MALE PERINEUM. 
 
 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 
 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 fossae : 
 nor can the urine make its way into the thighs. The only outlet 
 for it is into the connective tissue of the scrotum and penis. 
 
 4. When suppuration or extravasation of urine takes place 
 behind the ligament, the pus is pent up and should be speedily 
 let out ; if not, it may find its way into the connective tissue of 
 the pelvis, and may burst into the urethra or the rectum. 
 
 5. The ligament is partially cut through in lithotomy. 
 
 PARTS DIVIDED The parts divided in the lateral operation of 
 IN LATERAL lithotomy are : the skin, the superficial fascia, the 
 
 LITHOTOMY. transverse perineal muscle vessels and nerve, the 
 
 inferior haemorrhoidal vessels and nerves, the inferior fibres of the 
 accelerator urinse, the anterior fibres of the levator ani, the com- 
 pressor urethras, the triangular ligament (anterior layer), the 
 membranous and prostatic parts of the urethra, and a small portion 
 of the prostate. 
 
 PARTS TO BE The incision in lateral lithotomy should not be 
 
 AVOIDED. made too far forwards, for fear of wounding the 
 
 artery of the bulb ; nor too far inwards, for fear of injuring the 
 rectum ; nor too far outwards, for fear of cutting the pudic 
 artery. 
 
 c. The anterior layer of the triangular ligament 
 
 STRUCTURES J 
 
 BETWEEN THE must now be cut away to see what lies between its 
 
 LAYERS OF THE two layers. These parts are shown in fig. 92 ; 
 TRIANGULAR namely : 1, the membranous part of the urethra, 
 
 surrounded by, 2, the compressor urethrae 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 ; 5, the pudic nerve and its branches. 
 
 To obtain the best perineal view of the com- 
 pressor urethrae muscle, cut through the spongy 
 
DISSECTION OP THE MALE PERINEUM. 425 
 
 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. 93. 
 
 COMPBESSOB OB This muscle consists of transverse fibres which 
 CONSTRICTOR surround and support the urethra in its passage 
 
 URETHRJE. beneath the pubic arch. It arises from the ramus 
 
 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 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.* 
 
 COWPEK'S These small glands are situated, one on either 
 
 GLANDS. side, immediately behind the bulb between the 
 
 two layers of the triangular ligament, in the substance of the 
 compressor urethrse. Their size is about that of a pea, but it 
 varies in different individuals. They are compound racemose 
 glands, consisting of several lobules firmly connected together 
 by cellular and some muscular tissue. From each a slender 
 duct runs forwards, and, after a course of about one inch, 
 opens obliquely into the floor of the bulbous part of the urethra 
 (fig. 90). They furnish a secretion accessory to generation. 
 
 PUDIC AKTERY The pudic artery is a branch of the anterior 
 AND ITS division of the internal iliac. It leaves the pelvis 
 
 through the great ischiatic notch, above the ischiatic 
 artery, 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, between the layers of the obturator fascia, 
 up towards the pubic arch. About an inch and a half above the 
 
 * The compressor urethrse was first accurately described and delineated by Santo- 
 rini (septemdec. tabulae), and afterwards by Muller in his monograph (Ueber die organ, 
 Nerv. der manulich. G-eschlechtsorgane). 
 
426 
 
 DISSECTION OF THE MALE PEBINEUM. 
 
 tuber ischii, the trunk of the pudic artery can be felt ; but we can- 
 not see it, nor draw it out, for it is securely lodged in a fibrous 
 canal formed by the obturator fascia. In the present dissection 
 
 FIG. 93. 
 
 Catheter 
 
 Dorsal nerve of the penis _ 
 Dorsal artery of the penis . 
 Doraal vein of the penis . 
 
 Anterior layer of trian- 
 gular ligament .... 
 
 Ramns of pnbes cut throug' 
 Posterior layer of trian- 
 gular ligament : part of 
 the pelvic fascia . . . 
 
 DIAGRAM OF THE RELATIONS OF THE COMPRESSOR URETHEjE SEEN FROM ABOVE. 
 
 we find the artery between the two layers of the triangular liga- 
 ment, where it gives off its three chief branches, namely, the 
 artery of the bulb of the urethra, the artery of the cms penis, and 
 the dorsal artery of the penis (fig. 91). 
 
DISSECTION OF THE MALE PERINEUM. 427 
 
 Taken in order, the branches of the pudic artery are as 
 follows : 
 
 a. The external hcemorrhoidal, the superficial perineal, and the trans- 
 verse perineal branches have already heen described (pp. 417, 418). 
 
 b. 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, supposing the reverse, the vessel must be 
 divided. This deviation from the normal distribution is met with about 
 once in twenty subjects, and there is no possibility of ascertaining this 
 anomaly beforehand. 
 
 c. The artery of the crus penis, one of the terminal branches, 
 ascends for a short distance near the pubic arch and soon enters the 
 crus. 
 
 d. To see the dorsal artery of the penis, the penis should be dissected 
 from its attachment to the symphysis pubis. The artery can be traced 
 upon the dorsum of the penis down to the glans. It forms a complete 
 arterial circle with its fellow round the corona glandis, and gives 
 numerous ramifications to the papillae on the surface. 
 
 The veins corresponding to the branches of the pudic artery 
 terminate in the pudic vein, with the exception of the dorsal vein 
 of the penis. This runs along the middle of the dorsum of the 
 penis, and passing under the symphysis pubis opens into the 
 prostatic plexus. 
 
 The pudic nerve comes from the sacral plexus, 
 PUDIC NERYE. . r 
 
 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 (fig. 93). 
 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. 
 
428 SIDE VIEW OF THE PELVIC VISCERA. 
 
 ISCHIO-RECTAL This is the deep hollow, on each side, between 
 
 FOSSA, the anus and the 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 r , by the 
 rectum, levator ani and coccygeus ; posteriorly, by the gluteus 
 maximus ; anteriorly, by the transversus perinei. The fossa is 
 crossed by the external hsemorrhoidal vessels and nerves. 
 
 These deep spaces 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, and result in 
 a fistula. 
 
 ANATOMY OF THE SIDE VIEW OF THE PELVIC VISCERA. 
 
 To obtain a side view of the pelvic viscera, the 
 
 DISSECTION 
 
 left innominate bone should be removed thus : 
 Detach the peritoneum and the levator ani from the left side of 
 the pelvis, cut through the external iliac vessels, the obturator 
 vessels and nerve, and the nerves of the lumbar plexus ; then 
 saw through the pubes about two inches external to the sym- 
 physis, 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, and 
 a block placed under the sacrum. 
 
 The reflection of the peritoneum as it 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 
 
SIDE VIEW OP THE PELVIC VISCERA. 
 
 of the abdomen, has been already described. 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. 94. 
 FALSE LIGA- ^ ne peritoneal connections of the bladder are 
 
 called its false ligaments ; false in contradistinc- 
 tion to the true, which are formed by the fascia of 
 
 FIG. 94. 
 
 Peritoneum in dot- 
 ted outline . . 
 
 MENTS OF THE 
 BLADDER. 
 
 Bulb of the urethra 
 
 Cowper's gland 
 with duct . 
 
 Prostate . . . . 
 
 VERTICAL SECTION THROUGH THE PERINEUM AND PELVIC VISCERA. 
 
 (The arrows point out where the bladder can be tapped.) 
 
 the pelvis, and really do sustain 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 ; 
 the two lateral, by reflections of the peritoneum from the sides of 
 the pelvis to the sides of the bladder ; the superior is produced by 
 
430 
 
 SIDE VIEW OF THE PELVIC VISCEEA. 
 
 the passage of the peritoneum from the front of the bladder to the 
 abdominal wall. 
 
 To expose the pelvic fascia, the peritoneum 
 must be removed from that side of the pelvis 
 which has not been disturbed : in doing so, notice the abundance 
 of loose connective tissue interposed between the peritoneum and 
 
 PELVIC FASCIA. 
 
 FIG. 95. 
 
 Iliac fascia 
 covei-ing ilia- 
 cus internus. 
 
 Pelvic fascia 
 dividing. 
 
 Obturator fascia 
 covering obtu- 
 rator internus. 
 
 Becto-vesical 
 layer covering 
 levator ani. 
 
 Anal fascia 
 
 TRANSVERSE SECTION OF THE PELVIS, TO SHOW THE REFLECTIONS OF 
 
 THE PELVIC FASCIA. (After Gray.) 
 
 the fascia, to allow the bladder to distend with facility. When- 
 ever urine is extravasted into this loose tissue, it is sure to pro- 
 duce the most serious consequences ; therefore in all operations on 
 the perineum, it is of the utmost importance not to injure this 
 fascia. 
 
SIDE VIEW OP THE PELVIC VISCERA. 431 
 
 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. 95), the fascia is attached 
 superiorly to the body of the pubes,to the side of the pelvis just above 
 the obturator foramen, and to the greater ischiatic notch. Here 
 it becomes gradually thinner, covers the pyriformis muscle and the 
 sacral plexus, and is lost on the sacrum. From this attachment the 
 fascia descends as far as a line drawn from the 'spine of the ischium 
 to the symphysis pubis. Along this line, which corresponds with 
 the origin of a considerable portion 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, the outer layer of the pelvic fascia, 
 descends on the inner surface of the obturator internus, forming, 
 at the same time, a sheath for the pudic vessels and nerve, the 
 nerve being the lowest. It is attached to the arch of the pubes, 
 and to the tuberosities of the ischia. From this fascia is derived 
 the anal fascia.! which lines the under or permeal surface of the 
 levator ani, and is subsequently lost upon the side of the rectum. 
 
 The recto-vesical fascia is the continuation of the pelvic fascia, 
 and descends on the upper or internal surface 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 ligament incloses the vesicula 
 seminalis, and then passes between the bladder and the rectum, to 
 join its fellow from the opposite side. 
 
 GENERAL The pelvic viscera are so surrounded by veins 
 
 OSITIONOF TH an( j i ooge areo i ar tissue, that he who dissects them 
 
 IN THE MALE. f r the first time will find a difficulty in discovering 
 
432 SIDE VIEW OF THE PELVIC VISCERA. 
 
 their definite boundaries. The rectum runs at the back "of the 
 pelvis, and follows the anterior curve of the sacrum and coccyx. 
 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 surrounding the pros- 
 
 PLEXUS OF 
 
 VEINS ABOUT tate and the neck of the bladder are large and 
 
 PBOSTATK AND tortuous veins, which form the prostatic and the 
 NECK. OP vesical plexuses. They empty themselves into the 
 
 internal iliac. In early life they are not much 
 developed, but as puberty approaches they gradually increase in 
 size, and one not familiar with the anatomy of these parts would 
 hardly credit the size which they sometimes attain in old persons. 
 They communicate freely with the inferior hsemorrhoidal 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. 
 
 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. 
 
 KECTUM AND The intestinum rectum is about eight inches 
 
 ITS EELATIONS. long. It is a continuation of the sigmoid flexure 
 of the colon, enters the pelvis at the left sacro-iliac articulation, 
 describes a curve corresponding to the sacrum, and terminates 
 at the anus. Before its termination, the bowel turns downwards 
 so that the anal aperture is dependent. The rectum also inclines 
 from the left side to the middle line, and, although it loses the 
 sacculated appearance, 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 dila- 
 
SIDE VIEW OF THE PELVIC VISCEEA. 
 
 433 
 
 tation (fig. 94). This dilatation is not material in early life, but 
 it increases as age advances. 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 opera- 
 tion of lithotomy. 
 
 FIG. 96. 
 
 SIDE VIEW OF THE PELVIC VISCEBA. 
 
 (Taken from a Photograph.) 
 
 1. External sphincter. 
 
 2. Internal sphincter. 
 
 8. Levator ani cut through. 
 
 4. Accelerator urinse. 
 
 5. Membranous part of the urethra, sur- 
 
 rounded by compressor muscle. 
 
 6. Prostate gland. 
 
 7. Vesicula seminalis. 
 
 8. Ureter. 
 
 9. Vas deferens. 
 
 10. Crus penis divided. 
 
 11. Triangular ligament. 
 
 12. Superficial perineal fascia. 
 
 13. Kectum. 
 
 The upper part of the rectum (for about three inches and a 
 half) is connected to the sacrum by a fold of peritoneum termed 
 
 F F 
 
434 SIDE VIEW OF THE PELVIC VISCERA. 
 
 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 intestine is connected posteriorly to the 
 sacrum and coccyx by loose connective tissue, and is covered by 
 peritoneum in front, which forms the recto-vesical pouch. The 
 lower three inches and a-half are entirely destitute of peritoneum. 
 The rectum is supported by the levatores ani, the larger portions 
 of which are inserted into its side. 
 
 DIGITAL The relations of the front part of the rectum 
 
 EXAMINATION OF that, namely, included between the recto-vesical 
 THE RECTUM. pouch and the anus are most important. If the 
 
 forefinger be introduced into the anus, and a catheter into the 
 urethra, the first thing felt through the front wall of the bowel is 
 the membranous part of 'the urethra (fig. 94). 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 hardness ; by moving the finger from 
 side to side we recognise 1 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 distension of the bladder ; 
 the more distended the bladder, the better can the prostate be' 
 felt. These several relations are practically 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 comes from 
 the inferior mesenteric (p. 392) ; the middle and inferior from 
 the pudic artery. The superior and middle haemorrhoidal veins 
 join the inferior mesenteric, and consequently the portal system ; 
 the inferior haemorrhoidal veins join the internal pudic. They are 
 
SIDE VIEW OP THE PELVIC VISCEKA. 
 
 435 
 
 BLABBER. 
 
 very large and form loop-like plexuses 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 distension, may reach nearly up 
 
 FIG. 97. 
 
 1. Ureter. 
 
 2. Vas deferens. 
 
 3. Vesicula seminalis. 
 
 4. Trigone. 
 
 5. Prostate. 
 
 POSTERIOR VIEW OF THE BLABBER. 
 
 to the umbilicus.* Its outline can then be easily felt through the 
 walls of the abdomen. The form f of the distended bladder is 
 
 * "When the bladder is completely paralysed it becomes like an inorganic sac, and 
 there seems to be no limit, to its distension. 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. Ticiui, 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 anim.'ils 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. 
 
 F F 2 
 
436 SIDE VIEW OF THE PELVIC VISCERA. 
 
 oval, and its long axis, if produced, would pass superiorly through 
 the umbilicus, and inferiorly through the end of the coccyx. The 
 axis of a child's bladder is more vertical than that of 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. Much 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 
 bottom of the bladder gradually deepens so as to form a pouch 
 behind the prostate. In old subjects, particularly if the prostate 
 be enlarged, this pouch becomes deep, micturition becomes tedious, 
 and the bladder cannot completely empty its contents. It some- 
 times happens that a stone in the bladder is not 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 struck. 
 
 This tube is about seventeen inches long, and 
 conveys the urine from the kidney to the bladder. 
 In the dissection of the abdomen (p. 394), it was seen descending 
 along the psoas muscle, behind the spermatic vessels, and crossing 
 the common iliac artery into the pelvis. Tracing it downwards, 
 in the posterior false ligament of the bladder, we find that it runs 
 along the side of 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. 97). It per- 
 forates the bladder very obliquely, so that the aperture, being 
 valvular, allows the urine to flow into, but not out of it. The 
 narrowest part of the ureter is at the vesical orifice ; here, there- 
 fore, a calculus is more likely to be arrested in its progress than 
 at any other part of the canal. 
 
SIDE VIEW OF THE PELVIC VISCERA. 437 
 
 This tube, about twenty-four inches in length, 
 
 \ AS DEFEEKNS 
 
 conveys the seminal fluid from the testicle into 
 the prostatic part of the urethra. It ascends at the back part 
 of the spermatic cord through the inguinal canal into the abdo- 
 men ; then, leaving the cord at the inner ring, it curves round 
 the epigastric artery, then crosses over the external iliac vessels, 
 and descends into the pelvis on the side of the bladder, gradually 
 approaching 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. 97, p. 435). 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. 96). Each is 
 a tube, but so convoluted that it is like a little sacculated 
 bladder. When rolled up, the tube is about two and a half inches 
 long ; unrolled, it would be more than twice that length, and 
 about the size of a small writing quill. Several caecal prolonga- 
 tions proceed from the main tube, after the manner of a stag's 
 horn. The vesiculaB seminales do not run parallel, but diverge 
 from each other, posteriorly, as far as the reflection of the recto- 
 vesical peritoneal pouch, like the branches of the letter V ; and 
 each lies immediately on the outer side of the vas deferens, into 
 which it opens. The vesiculse seminales probably serve as reser- 
 voirs for the semen. 
 
 They contain a brownish-coloured fluid, presumed to be in 
 some way accessory to the function of generation, f 
 
 * The description in the text assumes the bladder to be distended. But when 
 the bladder is empty the vas deferens runs down upon the side 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. 
 
 t The vesiculae seminales are imperfectly developed till the age of puberty. In a 
 child of three years of age they can hardly be inflated with the blowpipe. 
 
438 SIDE VIEW OF THE PELVIC VISCEKA. 
 
 PEOSTATE The prostate gland is situated at the neck of 
 
 GLAND> the bladder, and surrounds the first part of the 
 
 urethra (fig. 96). In the healthy adult it is about the size and 
 shape of a chestnut. Its apex is directed forwards. It is sur- 
 rounded by a plexus of veins (p. 432), and is maintained in its 
 position by the pelvic fascia (p. 431). 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 are the membranous part of the urethra (sur- 
 rounded by its compressor muscle), and the triangular ligament ; 
 behind, are the neck of the bladder and the vesiculae 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 imperfectly de- 
 veloped : it gradually grows towards puberty, and generally in- 
 creases 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 readily within reach of the 
 finger. 
 
 The urethra is a canal about eight inches in 
 ANATOMY OF 
 
 THE UEETHEA length, and leads from the bladder to the end of 
 IN ITS PASSAGE the penis. It is divided into three portions the 
 prostatic, the membranous, and the spongy. At 
 present only the relations of the membranous 
 part, which comprises that part of the canal between the 
 prostate and the bulb, can be examined. The urethra in this 
 part is nearly one inch in length, but 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 compressor urethras, and below it are Cowper's 
 
SIDE VIEW OF THE PELVIC VISCERA. 439 
 
 glands. It traverses the two layers of the triangular ligament, 
 and is about an inch below the symphysis pubis, 1 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 coccy- 
 geus and compressor urethrae, forms a muscular floor for the 
 cavity of the pelvis. To see the muscle, the pelvic fascia must be 
 reflected from its' upper surface. It arises from the posterior 
 aspect of the pubes near the symphysis, from the spine of the 
 ischium, and, between these bones, from the tendinous line which 
 marks the division of the pelvic fascia into the obturator and 
 recto-vesical layers (p. 430). From this long origin the fibres 
 descend inwards, 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 (forming the ' so-called ' levator 
 prostatse) ; the middle are inserted into the side of the rectum, 
 while the posterior meet their fellow beneath the rectum. 
 
 The levator ani is supplied by the inferior rhsemorrhoidal, the 
 two lower sacral, and the coccygeal nerves, 
 
 The action 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 continu- 
 ation of the levator ani. It arises by its apex 
 from the spine of the ischium, gradually, spreads out, and is in- 
 
 * 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 
 sometimes called the recto-urethral triangle. 
 
440 SIDE VIEW OP THE PELVIC VISCERA. 
 
 serted into the side of the sacrum and the coccyx. This muscle 
 is supplied by the two lower sacral and the coccygeal nerves. 
 
 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. 
 
 INTERNAL From the division of the common iliac artery, 
 
 ILIAC ABTEEY the internal iliac descends into the pelvis, and, 
 AND BRANCHES. after a course of about an inch and a half, divides, 
 opposite the great sacro-ischiatic notch, into two large branches, 
 an anterior and a posterior (fig. 98). The artery lies upon the 
 
 FIG. 
 
 SAC LAT 
 PLAN OF THE BRANCHES OF THE INTERNAL ILIAC. 
 
 lumbo-sacral cord, the pyriformis muscle, the external and 
 internal iliac veins; the ureter, enclosed in the posterior false 
 ligament of the bladder, passing in front. 
 
 The posterior division gives off the ilio-lumbar; lateral sacral, 
 and giuteal arteries; the anterior gives off the superior vesical, 
 obturator, inferior vesical, middle h^morrhoidal, isehiatic and 
 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. 
 
 The branches of the posterior division are 
 
 . The ilio-lumbar is analogous to the lumbar branches of the 
 
SIDE VIEW OF THE PELVIC VISCERA. 
 
 441 
 
 aorta. It ascends 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 inoscu- 
 lates with the deep circumflexa ilii (fig. 98). 
 
 6. The lateral sacral, usually two in number, descend 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 cauda equina. 
 
 c. The gluteal is the largest branch. It passes immediately 
 out of the pelvis through the great ischiatic notch, above the pyri- 
 
 Fio. 99. 
 
 YIEW OF THE DIFFERENT DIRECTIONS WHICH AN ABNORMAL OBDURATOR ARTERY 
 
 MAT TAKE. (Seen from above.) 
 
 A. 1. Gimbernat's ligament. 
 
 2. Femoral ring. 
 
 3. Abnormal obturator artery. 
 
 4. External iliac vein. 
 
 5. 'External iliac artery. 
 
 6. Diminutive obturator artery arising 
 
 from its normal source. 
 
 B. 1. Gimbernat's ligament. 
 
 2. Abnormal obturator artery. 
 
 3. Femoral ring. 
 
 4. External iliac vein. 
 
 5. External iliac artery. 
 
 6. Diminutive obturator artery. 
 
 formis muscle, and then divides into branches for the supply of 
 the great muscles of the buttock. These will be dissected with 
 the thigh. 
 
 The anterior division gives off 
 
 a. The superior vesical artery comes off from the unobliterated 
 portion of the hypogastric, and supplies the upper part of the 
 
442 SIDE VIEW OF THE PELVIC VISCERA. 
 
 bladder. It gives off the middle vesical artery ; and a still smaller 
 one, the deferential, which accompanies the vas deferens. 
 
 6. The inferior vesical artery ramifies on the under surface of 
 the bladder, the vesiculse seminales and the prostate, and gives off 
 the middle hoemorrhoidal which supplies the rectum. 
 
 c. 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 lies between the peritoneum and the 
 pelvic fascia, and gives off a small branch^to the iliacus internus, 
 and another, the pubic., .whicb 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 
 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 neck of a femoral hernia, would 
 in such a case be surrounded by a large artery .-f- 
 
 d. The ischiatic artery is smaller than the gluteal. 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. 
 
 e. The pudic artery supplies the perineum, scrotum and penis. 
 In the pelvis it usually lies above the ischiatic, and rests upon the 
 
 * 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 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. 
 
 f The Museum of St. Bartholomew's Hospital contains two examples of double 
 femoral hernise 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.) 
 
SIDE VIEW OF THE PELVIC VISCERA. 443 
 
 pyriformis and sacral plexus, having the rectum to its inner side. 
 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 on the 
 inner side of the obturator muscle it is enclosed 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. 425). 
 
 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 proportionably small. Anatomists are 
 familiar with these varieties, and a winter session rarely passes 
 without meeting with one or two examples of them. It need 
 hardly be said that lithotomy, under such conditions, might be 
 followed by a large haemorrhage. 
 
 /. The middle sacral artery is a very diminutive prolongation 
 of the aorta down to the coccyx. It becomes gradually smaller, 
 and finally inosculates with the lateral sacral arteries. In 
 animals this is the artery of the tail. 
 
 Respecting 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. 432). 
 
 NEBVESOFTHE Those which proceed from the spinal cord 
 PELVIS. should be examined first, afterwards those de- 
 
 rived from the sympathetic system. 
 
 SACEAL Five sacral nerves proceed from the spinal cord 
 
 NERVES. through the anterior sacral foramina. The upper 
 
 four, from their large size, at once attract observation; but the 
 fifth is small : it perforates the coccygeus muscle, supplying it and 
 the skin over the coccyx. 
 
444 
 
 SIDE VIEW OF THE PELVIC VISCERA. 
 
 The lower part of the fourth sacral nerve does not form part 
 of the plexus ; it gives off branches to the pelvic organs, and 
 muscular twigs to the levator ani, coccygeus, and the external 
 sphincter. 
 
 The coccygeal nerve, not easily found, pierces the great sacro- 
 ischiatic ligament and coccygeus; it communicates with the fifth 
 
 Fro. 100. 
 
 12. N. of pyriformis. 
 
 13. N. of gemellus superior. 
 
 14. N. of gemellus inferior. 
 
 15. N. of quadratics femoris. 
 
 16. N. of glutens 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 gluteal n. 
 
 7. Great ischiatic n. 
 
 8. Lesser ischiatic n. 
 
 9. Pudic n. 
 
 10. N. of obturator internus. 
 
 11. N. of levator ani. 
 
 PLAN OF THE SACRAL PLEXUS AND BRANCHES. 
 
 sacral nerve, and supplies the same parts ; namely, the coccygeus 
 and the skin over the coccyx. 
 
 SACRAL The three upper sacral nerves, and part of the 
 
 PLEXUS. fourth, with the lumbo-sacral cord, form the 
 
 sacral plexus. The great nerves of the plexus lie on the pyri- 
 formis muscle, beneath the branches of the internal iliac artery, 
 and coalesce to form the great ischiatic nerve, which passes out at 
 
SIDE VIEW OF THE PELVIC VISCEEA. 445 
 
 the back of the pelvis, for the supply of the flexor muscles of the 
 inferior extremity. The other branches of the plexus are as 
 follows : 
 
 a. Muscular branches distributed to the levator ani, the coccy- 
 geus, the external 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. The branch to the inferior gemellus and quadratus fe- 
 moris passes beneath those muscles and enters their anterior 
 aspect. It also sends a filament to the hip-joint. 
 
 b. The superior gluteal nerve proceeds from the lumbo-sacral, 
 leaves the pelvis above the pyriformis with the gluteal artery, and 
 supplies the gluteus medius and minimus, and the tensor fasciae 
 femoris. 
 
 c. The lesser ischiatic supplies the gluteus maximus, the skin 
 of the buttock, the perineum, and the back of the thigh. 
 
 d. The pudic nerve runs with the pudic artery, and like it, 
 supplies 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. 
 
 SYMPATHETIC From the lumbar region the sympathetic nerve 
 
 NERVE. descends into the pelvis, along the inner side of 
 
 the sacral foramina. In this part of its course its ganglia vary in 
 number from three to five. The nerves of opposite sides unite 
 in front of the coccyx, where they form the ganglion impar. 
 
 The arrangement of the sympathetic nerves in the pelvis is 
 similar to that in the abdomen. Each ganglion receives 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 previously 
 hardened in spirit. They accompany the arteries supplying the 
 respective organs, and are called the vesical, prostatic, and 
 inferior hcemorrhoidal plexuses ; and in the female the uterine 
 and vaginal. 
 
446 BLADDEE, PROSTATE, UEETHEA, AND PENIS. 
 
 The vesical filaments of the sympathetic do not stop at the 
 prostate, but pass on beneath the pubic arch into the corpus caver- 
 nosum 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. 
 
 It is assumed that the parts have been collectively taken out 
 of the pelvis, and that the partial peritoneal covering of the 
 bladder has been removed. 
 
 The bladder, in a fairly dilated condition, measures about five 
 inches in length and three in breadth. 
 
 STRUCTURE OF The bladder is composed of a partial peri- 
 
 THE BLADDER. toneal coat, a muscular, and a mucous ; between 
 the last two there is -a layer of connective tissue, which the old 
 anatomists called the cellular coat. 
 
 The serous or peritoneal coat invests the posterior, lateral, 
 and superior surfaces of the bladder ; it is absent on the anterior 
 and inferior aspect. 
 
 The muscular coat is situated beneath the serous, and consists 
 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 
 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 thin layer of 
 circular fibres, especially developed near the neck, where they 
 form a sphincter sphincter vesicce. 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 
 
 * Miitler. 
 
BLADDER, PROSTATE, URETHRA, AND PENIS. 
 FIG. 101. 
 
 447 
 
 Prostate gland 
 
 Membranous part ot 
 the urethra . . . 
 
 Ureter. 
 
 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 lacuna. 
 
 Corpus cavernosnm 
 penis. 
 
 _ G lans penis, 
 
 BLADDER AND UHETHBA, LAID OPEN BY AN INCISION ALONG THE UPPER SURFACE. 
 
448 BLADDER, PROSTATE, UEETHRA, AND PENIS. 
 
 parts of the bladder, and more liable to the formation of pouches.* 
 The development and colour of the muscular fibres depend upon 
 how far the subject has suffered from irritation of the bladder, 
 or any obstruction to the expulsion of the urine. 
 
 The mucous coat is everywhere loosely connected to the 
 muscular, except at the trigone of the bladder, where they adhere 
 more firmly. 
 
 The bladder must be laid open by an incision along its front, 
 to examine its interior. In a recently contracted bladder, the 
 mucous membrane is disposed in irregular folds, which disappear 
 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 mucous follicles. These 
 follicles secrete the thick ropy mucus in inflammation of the 
 bladder. 
 
 The vesical orifice of the urethra is situated at the lower and 
 anterior part of the bladder, not at the most dependent part, which 
 forms the pouch behind the orifice, in which urine is apt to accu- 
 mulate in old persons. It appears small and contracted in the fresh 
 bladder, but if the little finger be introduced into it, it will dilate 
 considerably. Immediately behind the orifice there is, in some 
 bladders, a slight elevation, called the uvula. It is composed 
 of a portion of the mueous membrane raised up by an accumulation 
 of the submucous tissue, but is rarely of sufficient size to interfere 
 with the passage of the urine. This elevation must be dis- 
 tinguished from enlargement of the third or middle lobe of 4 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 
 
 * These pouches arise in the following manner : A portion of mucous membrane 
 is protruded through one 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 such 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 ensue. This explains our frequent inability to detect 
 its presence at each examination with the sound. 
 
TEIGONE OP THE BLADDER. 449 
 
 perforate the coats of the bladder obliquely, and slant towards 
 each other, standing out in relief under the mucous membrane.* 
 A slight ridge proceeds from the orifice of each ureter 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,f 
 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. 
 
 TEIGONE OF THE The ridges, converging from the ureters, form 
 
 BLADDER. with a horizontal line, drawn between their orifices, 
 
 a smooth triangular area, called^ by a French anatomist,! the trigone 
 vesicate. 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 provided 
 with blood-vessels and nerves than the rest of the bladder, and is 
 endowed with more acute sensibility. This is 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, middle, 
 and inferior vesical arteries. The superior comes from the un- 
 obliterated 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 veins of the bladder form large plexuses around its neck, 
 sides, and base, and empty themselves into the internal iliac veins. 
 The lymphatics follow the course of the veins. 
 
 * 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 lose their valvular direction, so that the urine, when the bladder 
 contracts, is partly forced back up the ureters ; the result is, that they become di- 
 lated, and the pelvis of the kidney also. 
 
 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.' 
 Lieutaud. 
 
450 PROSTATE GLAND. 
 
 Its nerves are derived from the hypogastric and sacral plexuses ; 
 the former is chiefly distributed to the top, the latter to the neck 
 and the bottom of the bladder. 
 
 Having already examined the form, size, and 
 PKOSTA.TB 
 
 relations of the prostate (p. 438), we have now 
 
 to make out its lobes. There are two lateral lobes, and a third 
 or middle lobe.* The middle one is pyriform in shape, unites the 
 lateral lobes, and is situated between them and the urethra. In 
 health, it does not appear like a separate lobe ; but when abnor- 
 mally enlarged, it projects toward 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. This canal runs rather nearer to 
 its upper than its lower surface, and is not of the same calibre 
 throughout.f 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 
 fading in front. This is called the crest of the urethra, and the 
 most prominent part of it is named the veru montanum, or caput 
 gallinaginis, from its supposed resemblance to the head of a wood- 
 cock. On each side of this prominence the seminal ducts open, 
 (p. 447). 
 
 Immediately in front of the caput gallinaginis, in the middle 
 line, is a small opening which will admit a probe. It leads back- 
 wards into a little cul-de-sac or pouch in the substance 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 
 
 * 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 pre- 
 paration prepared by Sir Everard in illustration is preserved in the Museum of the 
 Royal 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. 
 
 t This part of the urethra is about an inch and a quarter long, and about four 
 lines in diameter. 
 
PROSTATE GLAND. 45 I 
 
 shape, running backwards and upwards, with the narrowest part at 
 the orifice, and its length is about five or six lines. It ascends 
 between the lateral lobes of the prostate, and beneath the middle ; 
 its coats are comparatively thick with some muscular tissue 
 enclosed in them, and it is lined with squamous epithelium. 
 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 substance of the gland is permeated by the divisions and sub- 
 divisions of the ducts. They are not visible to the naked eye, but 
 if traced out with the microscope, they are seen to terminate in 
 blind sacculated extremities, upon which the capillaries ramify in 
 rich profusion.f 
 
 The prostate is composed of muscular as well as glandular 
 tissue. Nearly two-thirds of it is made up of plain muscular 
 fibres, arranged in a circular manner round the urethra, at its 
 vesical orifice, so as to form in conjunction with the vesical 
 muscular tissue, a sphincter. The anterior part of the prostate 
 is chiefly muscular, its fibres being continuous with those of the 
 membranous part of the urethra. 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 by the finger sufficiently to allow the extraction of even 
 large calculi. 
 
 Any change in the dimensions of the prostate affects the canal 
 which runs through it, and more or less obstructs the flow of urine. 
 If the entire gland be uniformly enlarged, the length of the pro- 
 
 * 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 considerable size, and distend the prostate into a sac, which 
 when examined by the rectum feels not unlike a bag of marbles. 
 
 f This was first demonstrated by the late Mr. Quekett. The same 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.' 
 
 a G 2 
 
452 VESICULJ3 SEMINALES. 
 
 static urethra is increased ; if the enlargement preponderate 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 
 eurve according to the part enlarged. When the middle lobe 
 becomes enlarged, there arises, at the neek 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 introduce a 
 catheter into the bladder, it sometimes happens that the end of 
 the instrument is pushed through this hypertrophied lobe.* 
 
 VESICUL.E The external appearance of these bodies has 
 
 SEMINALES. been already described (p. 437). Respecting their 
 
 structure, we find that they have an external coat derived from 
 the recto-vesical 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 honey-combed structure, 
 not unlike that of the gall-bladder. Unstriped muscular fibres 
 exist in the fibrous investment of the vesicula3 seminales, for 
 the purpose of expelling their contents, and are arranged partly 
 transversely, on their posterior part, and partly longitudinally, in 
 connection with the vesical muscular fibres. 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 ejacula- 
 tory duct (p. 435). The function of these bodies is twofold: they 
 act as reservoirs for the semen, and secrete a fluid accessory to 
 generation. 
 
 COWPEE'S The glands of Cowper have been examined in 
 
 GLANDS. 8 H U j n the dissection of the perineum (p. 425). 
 
 They are placed close to the urethra, one on either side, imme- 
 diately behind the bulb and between the two layers of the trian- 
 gular ligament. They consist of a number of lobules united 
 by firm connective tissue, and their collective size is somewhat 
 larger than a pea. Each pours its secretion by a minute duct 
 about an inch long into the bulbous part of the urethra. The 
 use of these glands is analogous to that of the vesiculae seminales 
 and the prostate : namely, to pour into the urethra a fluid acces- 
 
 * See the Museum of St. Bartholomew's Hospital, Prep. 8 and 21, Series xxix. 
 
URETHRA. 453 
 
 sory in some way to generation. They are found in all mam- 
 malia, and in some e.g. the mole they increase in size 
 periodically with the testicle. 
 
 The urethra is the canal which extends from 
 the bladder to the end of the penis, and serves 
 not only as the outlet for the urine, but to transmit 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. 433) ; the second inch, which passes under the 
 pubic arch, is surrounded by the compressor urethra? (p. 433); 
 the remainder of its course along the penis is surrounded by 
 erectile tissue, termed corpus spongk>sum. Hence it is divided 
 into the prostatic, the membranous, and the spongy- parts. 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 an abdominal 
 than a pelvic viscus, 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, A straight staff is 
 sometimes used in lithotomy. 
 
 In its contracted state, the sides of the urethra are in close 
 apposition; the appearance it presents on a transverse section 
 differs in the different parts of its course. Through the glans it 
 is flattened vertically; through the prostate it is crescentic, with 
 the convexity upwards, owing to the veru montanum. But 
 
 * 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. 
 
454 UBETHRA. 
 
 throughout the rest of its course the canal exhibits on section the 
 appearance of a transverse slit (fig, 102). 
 
 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 prostatic and the membranous parts have been de- 
 scribed (p. 438). 
 
 The spongy part of the urethra, so termed because it is sur- 
 rounded by the erectile tissue of the corpus spongiosum, is about 
 six inches long. That part of it running through the bulb is 
 
 FIG. 102. 
 
 A Ho 
 
 TBANSVEHSE SECTIONS OF THE TJKETHRA. 
 
 A. Through the prostate. B. Through the corpus spongiosum. 
 
 c. Through the glaus penis. 
 
 called the bulbous portion, and is the most dilatable part of the 
 canal except the prostatic. In the centre of the glans penis the 
 canal widens into a sinus, termed fossa navicularis. 
 
 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 three to four lines in diameter can 
 pass through it. 
 
 The common ejaculatory ducts open into the prostatic part of 
 the urethra, by the side of the veru montanum. The ducts of 
 Cowper's glands open into the bulbous part. Besides these glands, 
 a number of ducts open into the urethra, proceeding from small 
 glands situated in the submucous tissue. These ducts, called 
 lacunce, are large enough to admit a bristle, and run in the same 
 
UEETHRA. PENIS. 455 
 
 direction as the stream of the urine. Most of them are on the 
 lower surface of the urethra ; but one, called lacuna magna, is on 
 the upper surface, about one inch and a half down the canal. 
 
 Beneath the mucous membrane of the urethra is a layer of 
 areolar tissue, the submucous tissue, external to which is a layer 
 of vascular tissue of variable thickness ; outside this is a layer of 
 unstriped muscular fibres. 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 columnar stratified epithelium, except 
 near the glans, where there are papillae, covered with squamous 
 epithelium ; this, therefore, is the most sensitive part. 
 
 Lastly, the urethra is provided with a closely-set network of 
 lymphatic vessels, which has been demonstrated by quicksilver 
 injections.* They run from behind, forwards, and join the lym- 
 phatics of the glans penis. Eventually, their contents are trans- 
 mitted down the great trunks on the dorsum penis to the inguinal 
 glands. This explains the pathology of a bubo. 
 
 The skin of the penis is remarkably thin and 
 extensible, and connected to the body of the organ 
 by loose areolar 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 
 the glans to the prepuce is called frcenum preputii. The skin, 
 
 * Panizza, ' Osservazioni antropo-zootom.' &c , Pavia, 1830. This anatomist has 
 also displayed by injections an extremely fine network of lymphatics 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 inconveni- 
 ence 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 para- 
 phimosis. The neck of the glans becomes tightly girt ; great distension and in- 
 flammation are the consequences unless the foreskin be reduced. 
 
456 PENIS. 
 
 altered in character, is reflected over the glans, to which it is 
 intimately adherent, and at the orifice of the urethra is continuous 
 with the mucous membrane. 
 
 The surface of the glans is covered with minute vascular 
 papillae, 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 is 
 lodged a third cylindrical body, the corpus spongiosum, composed 
 of vascular spongy tissue, through which runs the urethra ; an ex- 
 pansion 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 (fig. 103). 
 
 The upper part of the penis is connected to the symphysis 
 pubis by an elastic triangular ligament, called ligamentum sus- 
 pensorium penis. 
 
 CORPORA The corpora cavernosa constitute more than 
 
 CAVEHNOSA. two-thirds of the bulk of the penis. Each com- 
 
 mences posteriorly by a gradually tapering portion, called the cms 
 penis, which is attached along a groove in the rami of the ischium 
 and pubes, where it is embraced by the erector penis (p. 420). 
 The two crura converge, come into apposition at the root of the 
 penis, and then run together side by side to form the body of the 
 organ. Anteriorly, each terminates in a rounded extremity, received 
 into a corresponding depression in the glans, to which it is con- 
 nected by fibrous tissue. 
 
 A section through the corpus cavernosum shows that its inte- 
 rior is composed of a delicate reticular structure, surrounded by 
 a white fibrous and elastic coat, from half a line to a line in 
 thickness. 
 
 The septum pectiniforme is a median vertical partition 
 
PENIS. 457 
 
 between the two corpora cavernosa ; it is only complete near the 
 root of the penis ; along the rest of the organ there are vertical slits 
 in it, giving it the appearance of a comb : hence its name. Through 
 the intervals in this partition the blood-vessels of the two corpora 
 cavernosa communicate freely with each other. 
 
 From the interior of the fibrous coat a number of delicate 
 septa, trabeculce, pass inwards into the corpus cavernosum, inter- 
 secting each other in all directions, and forming a multitude of 
 small spaces. The trabeculse consist of fibrous lamellae, with 
 elastic and some non-striated muscular tissue. The spaces com- 
 municate freely with each other, as may be readily ascertained by 
 blowing air into the penis ; they are smaller and their component 
 septa thicker at the circumference than in the centre of the corpora 
 
 FIG. 103. 
 
 1. Corpus cavernosum. /^^^prvjf^ *. ** Aeries. 
 
 2. Corpus spongiosum urethra. [j^|>.*^fJ/./.*;3] 5, 5. Dorsal nerve.. 
 
 3. Vena dorsalis. 
 
 TRANSVERSE SECTION THROUGH THE PENIS. 
 
 cavernosa, at the root than towards the glans. Each corpus 
 cavernosum thus consists of innumerable spaces mainly occupied 
 by dilated venous sinuses, from which the blood is conveyed by 
 the dorsal vein, the prostatic plexus, and the pudendal veins. 
 When the penis is flaccid, these spaces are empty ; when it is 
 erect, they are distended with blood. 
 
 The arteries of the corpora cavernosa come from the branches 
 of the pudic (p. 427), which 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 convey their blood 
 at once into the inter-trabecular spaces, others in tendril-like 
 prolongations with dilated extremities which project into the 
 
458 PENIS. 
 
 cavities of the veins. These arteries, called helicine, are ab- 
 sent near the glans, and are best marked at the root of the 
 penis. 
 
 The blood from the inter- trabecular spaces of the penis returns 
 partly through veins which pass out on the upper surface of the 
 penis into the 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. 
 
 CORPUS The corpus spongiosum is the erectile tissue 
 
 SPONGIOSUM. which surrounds the urethra as it runs along the 
 
 penis. It commences in the middle of the perineum, anterior to 
 the triangular ligament, in a bulb-Aike form the bulb and at 
 the end of the penis it expands to form the glans. It receives 
 posteriorly an expansion from the triangular ligament, and pre- 
 sents a median groove, marking its development from two lateral 
 halves. The urethra does not pass through the middle of the 
 spongy body, but runs nearer to its upper surface. The bulb 
 hangs more or less pendulous from the urethra, and is surrounded 
 by the accelerator urinae muscle (p. 420). In old persons it ex- 
 tends lower down than in children, and is, consequently, 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. 
 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, and its superficial 
 perineal branch. The largest branches run along the dorsum to 
 the surface of the glans : a few only enter the erectile tissue of the 
 organ. This, it has already been mentioned (p. 446), is supplied 
 
 * In the Museum of the Royal College of Surgeons there is a preparation in which 
 the glans penis is injected with quicksilver, clearly showing it to consist of a plexus 
 of reins. Physiol. Series, No. 2588 A. 
 
DISSECTION OP THE FEMALE PERINEUM. 450 
 
 by filaments of the sympathetic nerve proceeding from the hypo- 
 gastric plexus.* 
 
 The lymphatics proceeding from the glans and the integument 
 of the penis join the inguinal glands. The lymphatics 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. The deep lymphatics from the corpora cavernosa 
 and the corpus spongiosum join the lymphatics of the pelvis. 
 
 DISSECTION OF THE FEMALE PERINEUM. 
 
 The pudenda in the female consist of folds of the integument, 
 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 surmounted by an 
 
 accumulation of fat, called mons Veneris, which 
 is covered with hair. From this, two thick folds of skin descend, 
 one on either side, constituting the lakia majora, and gradually 
 diminish in thickness towards the perineum. Their junction, 
 about one inch above the anus, is called the posterior commissure, 
 or frcenulum 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 pus 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 observ- 
 able on the surface. 
 
 In form and structure the clitoris resembles the 
 
 penis on a diminutive scale, being about an inch 
 and a half long. It has, however, no corpus spongiosum, or 
 urethra. Like the penis, it is attached to the sides of the pubic 
 arch by two crura (fig. 104, p. 461), each of which is grasped by 
 its special erector clitoridis. The crura are continued forward 
 
 * Krause has described end-bulbs on the nerves, and Pacinian corpuscles have 
 likewise been discovered on the nerves of the glans. 
 
460 DISSECTION OP THE FEMALE PEEINEUM. 
 
 like the corpora cavernosa of the male, and unite to form the body 
 of the organ, which is surmounted by a small glans. The glans is 
 provided with extremely sensitive papillae, and covered by a little 
 prepuce. Its dorsal arteries and nerves are 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. 
 
 By separating the external labia, two small and 
 
 LABIA MINORA. .. . - fT \T^ * J 
 
 thin folds of integument are exposed, one on 
 either side, termed labia minora. These folds converge an- 
 teriorly, and form a covering for the clitoris, called preputium 
 clitoridis ; posteriorly they are gradually lost on the inside of the 
 labia majora. They, unlike the labia majora, do not contain fat, 
 but are composed of minute veins. Between the nymphse 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 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. 
 
 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, meatus 
 urinarius, is not a perpendicular fissure like that of the penis, 
 but rounded and puckered, and daring life has a peculiar 
 dimple-like feel, which assists us in finding it when we pass a 
 catheter. You should practise 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 forefinger 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. 464). The two canals are in such 
 close apposition that you can feel the urethra embedded in the 
 
DISSECTION OP THE FEMALE PERINEUM. 461 
 
 vagina like a thick cord. The urethra is slightly curved with the 
 concavity upwards ; but for all practical purposes it may be con- 
 sidered straight. Its direction, however, is not horizontal. In 
 the unimpregnated state 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 con- 
 sequence of their mutual connection ; therefore the urethra, in 
 the latter months of utero-gestation, acquires a much more per- 
 pendicular course. 
 
 The female urethra is provided with a compressor muscle, 
 similar, in origin and arrangement, to that which surrounds the 
 
 FIG. 104. 
 
 1. Meatus urinarius. / &jjf3tfe^&. \ 3 - Bulb of vagina. 
 
 2. Vagina. /~/M^iiL\ \ 4. Clitoris with its two crura. 
 
 4 
 
 2 / 
 
 BULB OF THE VAGINA.* 
 
 membranous part of the urethra in the male. It also passes 
 through the triangular ligament (fig. 105, p. 464). The prostate 
 gland is wanting, but there are minute glands scattered around 
 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. Ad- 
 vantage 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, and is lined by squamous epithelium, which changes to the 
 spheroidal variety near the bladder. Next to the mucous coat is 
 
 * Taken from an injected preparation in the Musee Orfila, at Paris. 
 
462 DISSECTION or THE FEMALE PERINEUM. 
 
 a layer of elastic and non striped muscular fibres intermixed. 
 Externally there 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 analogy to the bulb of the urethra 
 in the male. This vaginal bulb is about an inch long and extends 
 across the middle line between the meatus urinarius and the 
 clitoris, as shown in fig. 104. 
 
 The hymen is a thin fold of mucous membrane 
 which, in the virgin, extends across the lower 
 part of the entrance 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 perforated by several openings, hymen cmbriformis, 
 or by one only, hymen circularis. Again, there may be no open- 
 ing 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 
 
 When the hymen is ruptured, it shrivels into a few irregular 
 eminences, called carunculce myrtiformes. 
 
 The presence of the hymen is not necessarily a proof of vir- 
 ginity, nor does its absence imply the loss of it. Cases are re- 
 
 * Such a one may be seen in the Museum of the College, Phys. Series, No. 2843. 
 f See Burns' Midwifery. 
 
PELVIC VISCERA IN THE FEMALE. 463 
 
 lated by writers on midwifery in which a division of the hymen 
 was requisite to facilitate parturition. In Meckel's 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. 
 
 BAHTHOLIN'S Between the orifice of the vagina and the erector 
 
 OR DUVERNEY'S clitoridis is embedded in the loose tissue on either 
 GLANDS. s {^ e a sma il gland,* which corresponds to Cow- 
 
 per's gland in the male. Each is about half an inch in length. 
 Its long slender duct 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 
 and nerves, given in the dissection of the male perineum, applies, 
 mutatis mutandis, to the female, excepting that they are propor- 
 tionably 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 PELVIC VISCERA. 
 
 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. 
 
 ., The uterus is interposed between the bladder in 
 
 GENERAL r 
 
 POSITION OF THE front, and the rectum behind. From each side of 
 UTERUS AND ITS it a broad fold of peritoneum extends transversely 
 APPENDAGES. ^ o ^ e s ^ e o f ^he p e i v i s> dividing that cavity into 
 
 an anterior and a posterior part. These folds are called the broad 
 ligaments of the uterus (fig. 106, p. 473). On the posterior sur- 
 face 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 cord termed the ligament of the ovary. Along the upper 
 
 * See Tiedemann, ' Von den Duverneyschen Driisen desWeibs.' Heidelberg, 1840. 
 
464 
 
 PELVIC VISCERA IN THE FEMALE. 
 
 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 tentacles, grasp the ovum as soon 
 as it escapes from the ovary. One of these fimbrise is attached to 
 the ovary. Lastly, there run up to the ovary, between the layers 
 
 FIG. 105. 
 
 Urethra surround- 
 ed by its compres- 
 sor muscle . . . 
 
 Vagina . . . 
 
 Rectum . . . 
 
 Peritoneum in 
 dotted outline. 
 
 Uterus. 
 
 VERTICAL SECTION THROUGH THE FEMALE PELVIC VISCEHA. 
 
 of the broad ligament, the ovarian vessels, 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, on either side 
 between its layers, is the round ligament of the uterus. This 
 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 mons Veneris. Besides 
 
PELVIC VISCERA IN THE FEMALE. 465 
 
 one or two small blood-vessels, it contains muscular fibres analo- 
 gous to those of the uterus : these increase very much in preg- 
 nancy, so that, about the full term, the cord becomes nearly as 
 thick as the end of the little finger. In early life, the round liga- 
 ment receives a covering from the peritoneum which advances in a 
 tubular form into the inguinal canal. It corresponds to the pro- 
 cessus vaginalis of the peritoneum in the male. It is called the 
 canal of Nuck, and is generally obliterated in the adult. It may 
 be the seat of a hernia. 
 
 SIDE VIEW OF After the removal of the innominate bone, as 
 
 THE FEMALE described at p. 428, the vagina, rectum, and 
 
 PELVIC OBGANS. bladder should be moderately distended, and a 
 catheter passed into the urethra. This done, the reflections of the 
 peritoneum must be traced. 
 
 EEFLECTIONS From the front of the rectum the peritoneum 
 
 OF THE PEBI- is reflected on to a small part of the posterior wall 
 
 TONEUM. o f ^0 vagina, thus forming what is called the 
 
 recto-vaginal pouch. From the vagina the peritoneum is con- 
 tinued over the posterior surface, but only about half-way down 
 the front of the uterus ; thence it is reflected 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. 473). 
 
 In cases of ascites the fluid might distend the recto-vaginal 
 pouch, and bulge into the vagina, so that it would be practicable 
 to draw it off through this channel. 
 
 To the description of the fascia already given in 
 PELVIC FASCIA.. 
 
 the dissection of the male pelvis (p. 430) 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 the uterus in 
 its proper level in the pelvis. When, from any cause, the fascia 
 becomes relaxed, there is a liability to prolapsus uteri. 
 LEVATOB ANI. For the description of this muscle see p. 439. 
 
 The female bladder is broader transversely, 
 BLADDEB. 
 
 and, upon the whole, more capacious than the male. 
 
 H H 
 
466 PELVIC VISCERA IN THE FEMALE. 
 
 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. 
 
 VENOUS Though the veins round the neck of the bladder 
 
 PLEXUS ABOUT are comparatively small in the female, attention 
 THE VAGINA. should be directed to the plexus of large veins 
 
 which surround the vagina. They communicate freely with the 
 veins about the rectum, and empty themselves into the internal 
 iliac. Their congestion in pregnancy sufficiently accounts for the 
 dark colour of the vagina and the external organs, and the frequent 
 occurrence of hsemorrhoidal tumours.* These veins must be re- 
 moved, with the connective tissue in which they are embedded, 
 before a clear view of the parts can be obtained. 
 
 The urethra has already been described (p. 460). 
 
 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 
 a fistulous communication remains between them, through which 
 urine constantly dribbles. 
 
 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 dif- 
 ference 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 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 sixth 
 month, bled to death from the bursting of a large vein in the vagina. Other cases of 
 the kind are related by Siebold. 
 
PELVIC VISCEEA IN THE FEMALE. 467 
 
 during life, feel the neck of the uterus projecting at the top of it ; 
 higher up, or lower down, according to circumstances. For in- 
 stance, 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 
 upwards ; it corresponds with the axis of the outlet of the pelvis. 
 
 The width of the vagina is not uniform throughout. The 
 narrowest 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 
 speculum with the least amount of pain, the blades of the speculum 
 should be vertical when introduced into the orifice, and afterwards 
 turned horizontally. 
 
 The uterus is the hollow muscular organ which 
 UTEBUS. 
 
 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 de- 
 scribed (p. 463). 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 attained a certain size. 
 
 The uterus in the unimpregnated state is pyriform, or rather 
 triangular with the angles rounded, and is somewhat flattened 
 antero-posterioiiy. Its average si/e 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 preg- 
 nancies, and other causes. 
 
 For convenience of description, the uterus is divided into the 
 fundus, the body, and the cervix. The term fundus is applied to 
 the broadest part, which lies above the level of the Fallopian 
 tubes (p. 464). The body is the central part, while the cervix is 
 
 H H 2 
 
468 PELVIC VISCERA IN THE FEMALE. 
 
 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, os uteri, is at the apex of the neck. 
 
 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 corre- 
 
 VAGINAI, spond to the spermatic arteries in the male) given 
 
 ABTEEIES. . o ff f rom the abdominal aorta (p. 385), each inter- 
 
 nal iliac artery furnishes a branch to the uterus and another to the 
 vagina. 
 
 The uterine artery proceeds from the anterior division of the 
 internal iliac, towards the neck of the uterus, between the layers 
 of 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, and with a small branch from the ovarian 
 artery. 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 
 distributes branches to 1 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. 
 ' NERVES OF THE The nerves of the uterus are derived from the 
 UTERUS. third and fourth sacral nerves, from the hypo- 
 
 gastric and ovarian plexuses (p. 408). They accompany the blood- 
 vessels in the broad ligament to the neck of the uterus, and ascend 
 with them along its sides. 
 
 Some small filaments continue with the vessels, and form 
 around them plexuses, upon -which 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. 
 * Beck, 'Philosophical Transactions ' for 1846. 
 
PELVIC VISCERA IN THE FEMALE. 409 
 
 The nerves of the uterus enlarge during, pregnancy like the 
 arteries. Surgically speaking, the os uteri may be said to have no 
 nerves ; for it is insensible to the cautery and to the knife. 
 
 The lymphatics -of the uterus are small in its unimpregnated 
 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 arteries,, 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. 
 
 g The uterus, vagina, ovaries, and Fallopian tubes 
 
 THE VAGINA, should now be collectively removed from the pelvis 
 
 UTERUS, OVARIES, for the purpose of examining their internal struc- 
 AND FALLOPIAN ture 
 
 The vagina having already been laid open, 
 (p. 466), we observe that, it is lined by a mucous membrane of a 
 pale rose colour; and 'that it is rougtu-and < furrowed, especially 
 near the orifice. Two ridges, columnce ruganum, run one , along 
 its anterior, another along its posterior wall. From either side of 
 these proceed a series of transverse ridges rugce 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 themselves also possess 
 keen sensibility, being richly endowed with papillae. 
 
 The mucous membrane is provided with numerous papilla?, 
 conical and filiform, and covered with a thick lining of squamous 
 epithelium.. In the submucous tissue is an abundant supply of 
 muciparous glands, which increase in number and size towards 
 the uterus. 
 
 The chief strength of the vagina depends upon, a fibre-cellular 
 coat, about one-twelfth 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 
 
470 PELVIC VISCERA IN THE FEMALE. 
 
 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 vagince (p. 462). 
 Superiorly, the vagina is intimately attached to the neck of the 
 bladder, while to the rectum it is but loosely connected. 
 
 Before the uterus is laid open, examine the 
 UTERUS 
 
 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 posteriorly. 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 felt first in an examination per vaginam.* 
 The length, however, and the general appearance of the vaginal 
 part of the cervix vary according to the age ; it is also consider- 
 ably 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, f 
 
 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, slit up a long narrow 
 canal which leads up into it through the neck. This canal, which 
 
 * 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. Krause, Weber, 
 Busch, and others, say the anterior is the longer ; Mayer, Meckel, Quain, and others, 
 the posterior. 
 
 f 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 mouth, 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 shortly the lady became preg- 
 nant. (Hyrtl, ' Handbuch-der ^op. Anatoiri.') 
 
PELVIC VISCEEA IN THE FEMALE. 471 
 
 is about an inch in length, is not of the same dimensions through- 
 out : 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 cer- 
 vix. It remains unchanged in pregnancy for some time after the 
 cavity in the body has expanded, 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 
 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. In olden time it was called ' arbor vitce." 1 The rough- 
 ness produced by these ridges occasions an impression as though we 
 were touching cartilage when a sound is introduced 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 impregnation, the 
 secretion becomes so firm 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 oc- 
 casionally 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. ' De sterilitate mulierum.' Lips., 1707. 
 
472 PELVIC VISCERA IN THE FEMALE. 
 
 The mucous membrane of the uterus is more delicate and 
 softer 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 lower part of 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 
 (uterine glands) arranged at right angles to its surface. These 
 tubes pass outwards in a more or less spiral manner, some 
 of them appearing branched and dilated at their extremities. 
 They become greatly developed shortly after impregnation, and 
 take an important part in the formation of the membrana 
 decidua. 
 
 The greater part of the walls of the uterus consists of non- 
 striped or involuntary muscular fibres, which are chiefly aggre- 
 gated at the fundus, less so at the junction of the Fallopian tubes. 
 The texture of these fibres is so close and so interwoven that in 
 the unimpregnated uterus it is useless to attempt to trace them. 
 The fibres are arranged in three layers, an external, a middle, 
 and an internal. The external layer, placed immediately beneath 
 the peritoneum, is thin, and its fibres run transversely round the 
 uterus, some of them being continued in an oblique direction 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 and thickest 
 layer is composed mainly of concentric circles which surround the 
 orifices of the Fallopian tubes; at the cervix its fibres are ar- 
 ranged transversely, forming a 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 fcetus, the muscular 
 fibres perform another very important function: they close the 
 large venous sinuses consequent upon the great increase in the 
 amount of blood during pregnancy. Therefore, little haemorrhage 
 accompanies the expulsion of the placenta, provided it have been 
 
PELVIC VISCERA IN THE FEMALE. 
 
 473 
 
 attached to the fundus or the side of the uterus. But everyone 
 knows the danger of what is called placenta prcevia. Here, the 
 placenta, placed entirely or partly 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 
 checking, the bleeding. For the same reason, paralysis of the 
 muscular fibres in immediate connection with the placenta, be it 
 where it may, is likely to be a source of serious haemorrhage in 
 parturition. 
 
 FALLOPIAN The Fallopian tubes or oviducts are situated, 
 
 TUBES, one on each side, along the upper border of the 
 
 Fra. .106, 
 
 DIAOBAM OF THE UTEBTIS, ITS BEOAD LIGAMENTS, THE OVAHIES AND FALLOPIAN TUBES. 
 SEEN FfiOM . BEHIND. 
 
 1. Uterus. 
 
 2. Ovary, with its ligaments. 
 
 3. Fallopian tube. 
 
 4. Fimbriated extremity of Fallopian tube. 
 
 5. 5. Broad ligament. 
 
 6. Vagina. 
 
 broad ligament of the uterus, and convey the ovum from the 
 ovary to the uterus (fig. 106). They are about three or four 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- 
 lopian tube extends about an inch beyond the ovary ; and, by float- 
 ing it in water, one or two of the fimbriaB may be seen connected 
 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 
 
474 PELVIC VISCERA IN THE FEMALE. 
 
 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 pro- 
 vided with a columnar ciliated epithelium. The free end of the 
 tube communicates with the cavity of the peritoneum. This is 
 the only instance where a mucous membrane is directly con- 
 tinuous with a serous one. It explains how the embryo 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 non-striped muscular fibres : the outer layer being 
 arranged longitudinally; the inner, in circles. 
 
 The ovaries (called by Galen, testes muliebres) 
 are situated at the back of the broad ligament of 
 the uterus, between its two layers, but more or less suspended 
 by a short fold of peritoneum. Besides this, they are con- 
 nected on their inner side to the uterus by a thin cord, called the 
 ligament of the ovary. They are oblong, 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, which is covered with columnar 
 epithelium, and beneath it a proper fibrous coat, the tunica albu- 
 ginea. If a section be made through the ovary, you find that 
 it contains transparent vesicles, embedded in a soft fibro-nuclear 
 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 
 
STRUCTURE OF THE LIVER. 475 
 
 Graafian vesicles.* They vary in number from eight to thirty, 
 and in size from that of a pin's head to a pea.f The smallest are 
 near the centre; but as they advance towards maturity, they 
 gradually approach the surface, increasing at the same time in 
 size. Their proper tunic is very vascular and lined by several layers 
 of granular prismatic epithelium cells, called the tunica granulosa, 
 and 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,| surrounded by a layer of 
 granular cells called the discus proligerus. It is this ovum which, 
 escaping from the Graafian vesicle on the surface of the ovary, 
 is grasped by the fimbriated end of the Fallopian tube and con- 
 veyed into the uterus. The ruptured vesicle is converted soon 
 afterwards into a yellowish-looking mass called corpus luteum, 
 which persists for a while, and degenerates afterwards into a small 
 stellate 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. The 
 ovarian veins form, like the spermatic veins, near the ovary the 
 pampiniform plexus, and then terminate, the right in the inferior 
 vena cava, the left in the renal. 
 
 DISSECTION OF THE ABDOMINAL VISCERA. 
 
 The liver is the largest gland in the body, and 
 THE LIVER. . . & & , 
 
 in the adult weighs trom nity to sixty ounces. 
 
 Its surface is entirely covered by peritoneum, except a small part 
 behind, which is connected to the diaphragm and the upper part 
 of the right kidney by cellular tissue, and, again, in the hollow for 
 
 * So called after De Graaf, a Dutch anatomist, who discovered them in 1672, and 
 believed they were the true ova. 
 
 f From the y^tti to the ^th of an inch in diameter. 
 
 J This was first distinctly pointed out by Von Baer in 1827. 
 
476 STRUCTURE OF THE LIVER. 
 
 the gall-bladder. Behind, the liver, is thick and, round, but 
 towards the front it gradually slopes to a sharp, border.. The 
 upper surface is smooth and -convex, in adaptation to the dia- 
 phragm, and is marked by a white line which indicates its divi- 
 sion into a right and left lobe, the right being the larger. The 
 under surface is irregular and marked by five fissures which map 
 out the five lobes (fig. 107) : 1. The lonqitu- 
 
 FlSSUEES . 
 
 dinal fissure, dividing 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 pos- 
 terior border of the liver, contains the remains of what was, in 
 the foetus, .the ductus venosus r and is therefore called the fissure, 
 for the ductus venosus. 3.. The KolLow or fissure for the gall- 
 bladder. In the same line with this is, 4, the fissure for the 
 inferior vena cava, which passes obliquely inwards towards the 
 posterior border of the liver. 5. The transverse or portal 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 portay and between them the hepatic 
 artery. The relative position of these fissures (the liver being in 
 situ) may be best impressed on. the memory by comparing them 
 collectively 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 the under surface of the right lobe are two shallow fossce ; the 
 anterior is for the hepatic flexure, of the colon, the posterior for 
 the right 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 for the ductus venosus, and 
 the vena cava, and the transverse fissure ; and,, behind the trans- 
 verse fissure, it is connected to the right lobe by a ridge the 
 
STRUCTUBE OP THE LIVER. 
 
 477 
 
 lobulus caudatus. The lobulus quadratus is situated between 
 the gall-bladder, the longitudinal, and the transverse fissure. This 
 lobe is occasionally connected with the left lobe by a bridge of 
 hepatic substance (ports hepatis) which arches over the longi- 
 tudinal fissure. 
 
 The liver has five ligaments, of which the coronary, the right 
 and left lateral, and the falciform are reflections of the peritoneum ; 
 the fifth is the round ligament in the anterior free border of the 
 falciform ligament ; it consists of the remains of the umbilical 
 vein. The ligaments have been previously described (p. 377). 
 
 FIG. 107. 
 
 1. Longitudinal fis- 
 sure. 
 
 ?. Continuation of 
 the longitudi- 
 nal fissure (for 
 the ductus ve- 
 nosus). 
 
 3, Transverse fis- 
 sure. 
 
 4. Gall-bladder. 
 
 5. Venacavainits 
 
 groove. 
 
 6. Right lobe. 
 
 7. Left lobe. 
 
 8. Lobulus Spigelii. 
 
 9. Lobulus cauda- 
 
 tns. 
 
 10. Lobulus quad- 
 rat us. 
 
 DIAGRAM OF THE UNDEB SURFACE OF THE LITEH. 
 
 The liver is surrounded by a thin areolar coat or capsule, best 
 seen on those parts of it not covered with peritoneum. This coat 
 is connected to the 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 Glisson's capsule, 
 which surrounds the vessels as they enter that fissure, and in- 
 closes them in a common sheath in their ramifications through 
 the liver. 
 
 The inter-lobular areolar tissue is exceedingly delicate ; hence 
 
478 
 
 STRUCTURE OF THE LIVER. 
 
 LOBULES. 
 
 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 small 
 polyhedral masses called lobules, which range from 
 an inch in diameter. These lobules are marked 
 out by septa of areolar tissue, and in a transverse section have the 
 appearance of mosaic pavement (fig. 108) ; but in a perpendicular 
 section they somewhat resemble an oak-leaf (fig. 109). Each 
 lobule consists of a minute plexus of blood-vessels, ducts, and cells 
 
 To of 
 
 . Inter-lobular vein. 
 
 6. Intra-lobular or cen- 
 tral vein. 
 
 TRANSVERSE SECTIONS OF THREE LOBULES OF THE LITER, MAGNIFIED TO SHOW 
 THE POBTAL VENOUS PLEXUS. 
 
 (After Kiernan.) 
 
 hepatic cells which latter fill up the spaces between the rami- 
 fications 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 inclosed in a sheath of areolar tissue, 
 called Glissori's capsule ; 2, that the hepatic veins run alone from 
 first to last, and terminate in the inferior vena cava as it passes 
 under the liver. 
 
 The portal vein, on entering the substance of the liver, gives 
 off numerous small branches, which pass between the lobules and 
 
STRUCTURE OF THE LIVER. 
 
 479 
 
 LONGITUDINAL SECTIONS OF THB 
 LOBULES OF THE L1VEB. INTRA- 
 LOBULAB TEINS SEEN JOINING THE 
 STJB-LOBULAB. 
 
 form the inter-lobular or peripheric veins (fig. 108). The inter- 
 
 lobular veins give off a minute FIG. 109. 
 
 capillary network which penetrates 
 
 into the interior of the lobules and 
 
 freely communicates in the centre 
 
 with a single trunk called the intra- 
 
 lobular or central vein. This cen- 
 
 tral vein returns the blood from the 
 
 lobule, and opens immediately into 
 
 a sub-lobular vein, larger or smaller 
 
 as the case may be, upon which the 
 
 lobule is sessile (fig. 109).. 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 Centering the liver at the transverse fissure, 
 divides and subdivides with the portal vein and the biliary ducts, 
 and ramifies with them between the lobules. The artery distri- 
 butes branches which supply the coats of the hepatic vessels and 
 Grlisson's capsule vaginal branches and the capsule of the liver 
 capsular branches ; other branches pass into the lobules and 
 join the capillary network which leads to the radicles of the cen- 
 tral vein. 
 
 The minute capillary network which forms the basis of the 
 lobule radiates from the periphery to<the centre. The capillaries 
 average about -^ sVo ^ an 
 
 The biliary ducts form a close network round the circum- 
 ference of each lobule. From this network of biliary capillaries 
 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 vary- 
 ing from g-i-o- to j-oVo f an i ncn - They contain more or less 
 granular-matter, and in some cases fat-globules : when these 
 
480 STKTTCTUBE OF THE LIVEE. 
 
 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, to discharge their contents 
 into the hepatic ducts.* 
 
 The lymphatics of the liver, superficial and deep, commence 
 in the spaces in the interior of the lobule, accompany the inter- 
 lobular vessels, and pass out at the transverse fissure. The 
 superficial lymphatics are in connection with the areolar sheath 
 and the upper surface of the liver. 
 
 The nerves of the liver are derived from the pneumogastric, 
 chiefly the left ; and from the hepatic plexus which comes from 
 the cceliac plexus. These plexuses enter the liver at the trans- 
 verse fissure, surround the hepatic artery and the portal vein, and 
 accompany these vessels in their ramifications through it. The 
 ultimate termination of these nerves is not known. 
 
 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. 2. It forms a sub- 
 stance, glycogen, easily converted into sugar, which passes into the 
 hepatic veins, and being consumed, 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 lac- 
 teals. 4. The bile acts as a natural aperient. 5. The bile is an 
 antiseptic, and probably prevents the decomposition of the food 
 during its passage through the intestine. 
 
 The gall-bladder, or reservoir for the bile, is 
 
 GALL-BLADDER. . 
 
 confined by the peritoneum in a slight depression 
 
 on the under surface of the right lobe of the liver (p. 477). It is 
 pyriform in shape, is about four inches long, and capable of hold- 
 ing about 1 ^ oz. of fluid. Its narrow end, or neck, makes a bend 
 downwards, and terminates in a duct, called the cystic, which, 
 after a course of about an inch and a half, joins the hepatic duct 
 at an acute angle (fig. 81, p. 387). The common duct, ductus 
 communis choledochus, formed by their union, is about three or 
 
 * For further information on this subject see the original observations of Kiernan 
 in the ' Philosoph. Trans.' for 1833. 
 
STRUCTURE OF THE SPLEEN. 481 
 
 four inches long, and opens into the back of the descending part 
 of the duodenum, 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 connective tissue, contains 
 involuntary muscular fibres, which run mainly in the long axis of 
 the gall-bladder; the inner is the mucous coat. 
 
 It is supplied with blood from the cystic branch of the right 
 hepatic artery; its blood is returned by the cystic vein which 
 opens into the vena portse ; its nerves are derived from the cystic 
 branches of the hepatic plexus. 
 
 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-combed appearance. This appearance is 
 most marked in the middle of the gall-bladder: in the de- 
 pressions between the ridges may be seen, with a lens, numerous 
 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 
 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, 
 while digestion is not going on. The bile becomes during its 
 .sojourn in the gall-bladder very viscid and intensely bitter. 
 
 The spleen is a very vascular sponge-like organ, 
 and belongs 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. 
 It is of a reddish-blue colour. It is more or less elliptical in shape, 
 and in its natural position is placed with its long axis nearly 
 vertical. Its outer surface, which corresponds to the ninth, tenth, 
 and eleventh ribs, is adapted to the diaphragm and ribs, and is 
 smooth and convex; its inner, adapted to the great end of the 
 
 i i 
 
482 STRUCTURE OP THE SPLEEN. 
 
 stomach, is concave, and divided into an anterior and a posterior 
 portion by a vertical fissure the hilus at 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, tunica propria, 
 not only covers the spleen, but sends throughout its substance 
 fibrous cords (trabeculoe), which cross in various directions, and 
 thus form an intricate network of what are called trabecular spaces. 
 Besides this, the "trabeeulse form sheaths and supports for the splenic 
 vessels throughout their ramifications. The whole of this fibrous 
 framework is exceedingly elastic to admit of the varying size of the 
 spleen, and contains more or less non-striped muscular tissue. 
 
 The trabecular spaces, above described, are filled with what is 
 called the pulp ^)f the spleen. This pulp is a soft reddish-brown 
 substance, and, under the microscope, is found to consist of con- 
 nective-tissue corpuscles, which, with their communicating pro- 
 cesses, make up a fine retiform tissue, the interstices between which 
 are filled with red and white blood-corpuscles. Broadly speaking, 
 then, the spleen pulp is composed chiefly of cells. 
 
 The splenic artery enters at the hilus of the spleen, by several 
 branches, which ramify in its substance ensheathed and supported 
 by the fibrous framework* The smallest branches leave the 
 trabeculse, and, entering the splenic pulp, terminate in minute 
 vessels, arranged in pennicillate tufts. They open, and therefore 
 pour their blood directly, into the pulp tissue. The veins are said 
 to commence in the pulp tissue in the same way as the arteries 
 terminate in it, and to travel along the trabeculse like the arteries ; 
 but they communicate freely, and are so far unlike the arteries. 
 
 In the pulp of the spleen we also find what are called the 
 Malpighian corpuscles.-f They are about -^ of an inch in 
 
 * The ramifications of the splenic artery may be seen by washing away the pulp, 
 and floating the flocculeat-looking spleen in water. 
 
 { It is useless to lojk for them in the human spleen, unless the subject be ei- 
 
STRUCTURE OP THE KIDNEY. 483 
 
 diameter, visible to the naked eye, and look like white spots scat- 
 tered through the dark pulp. They are attached to the sides of 
 the arteries, and are said to be lymphoid expansions of the con- 
 nective tissue coat or outside coat of the arteries. These curious 
 spherical bodies are filled with lymph-corpuscles. They appear 
 not to have definite boundaries, but to communicate freely with 
 the reticular spaces of the pulp. 
 
 The lymphatics of the spleen run between the layers of the 
 gastro-splenic omentum to the lymphatic glands. 
 
 The function of the spleen is not yet accurately ascertained. 
 It appears to be, essentially, a great blood-gland ; and that it 
 consists of chambers filled with gland- cells of various size, 
 between which ramify minute arteries and veins. It is pre- 
 sumed 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, two in number, are situated in 
 -the lumbar region, embedded in fat. Their 
 colour is reddish-brown. Each is about 4 inches in length, and 
 2 inches in breadth, and weighs about 4^ ounces in the male, 
 rather less in the female. The left, usually situated higher 
 than the right, is generally longer and somewhat heavier. 
 The anterior surface of each is smooth and convex ; the posterior 
 rather flattened. The upper end of the kidney is larger and 
 thicker than the lower ; 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 is 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 
 
 ceedingly 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 J. 
 of an inch in diameter. 
 
 I i 2 
 
484 
 
 STRUCTURE OF THE KIDNEY. 
 
 FIG. 110. 
 
 capsule does not penetrate into the interior of the kidney, and 
 can be readily stripped off when healthy, 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. 110); the apices 
 of these, termed papillae, project 
 into one of the terminal divisions 
 of the excretory tube. The pyra- 
 mids are surrounded by the cor- 
 tical substance which dips down 
 between them ; they are composed 
 of minute straight tubes, which 
 proceed from the cortical portion 
 to end on the papillae. f 
 
 The cortical structure is deeper 
 in colour than the medullary, 
 forms the outer part of the kidney, and dips down between the 
 pyramids. It consists of convoluted tubes, which become dilated 
 at their extremities into what are called the Malpighian capsules. 
 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 
 
 * 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, 
 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. 
 
 SECTION OF THE KIDNEY. 
 
 1. Ureter. 
 
 2. Pelvis of the kidney. 
 
 3. 3, 3. Papulae. 
 
STRUCTURE OP THE KIDNEY. 
 
 485 
 
 from eight to twelve cup-like excavations, called the calyces. Into 
 each of these calyces one, sometimes two or more papillae project. 
 Between the calyces the branches of the renal artery ascend to 
 ramify in the kidney, lying embedded in fat. With a lens, the 
 papillae may be seen studded with minute apertures, which are 
 
 FIG. 111. 
 
 1. Malpighian capsule. 
 
 2. Convoluted tube. 
 
 3. Descending limb. 
 
 4. Ascending limb of 
 
 Henle's loop. 
 
 5. Junctional tube. 
 
 6, 7. Different portions of 
 
 straight tube. 
 8. Excretory tube. 
 
 a. Apex ol pyramid. 
 
 b. Base of pyramid. 
 C. Cortical portion. 
 
 DIAGRAM OF THE COURSE AND ARRANGEMENT OF THE URINIFEROUS TUBES. 
 
 (Ludwig.) 
 
 the terminations of the uriniferous tubes. These tubes as they 
 pass outwards run straight, bifurcate repeatedly at very acute 
 angles, and reach the sides and the bases of the pyramids. They 
 then enter the cortex in bundles of straight tubes, forming the 
 pyramids of Ferrein. They vary from the -^-^th to the -^ O th of 
 
486 
 
 STRUCTURE OF THE KIDNEY. 
 
 an inch in diameter, and are largest towards their termination. On 
 entering the cortex, the tubes become convoluted, and are sur- 
 rounded by minute plexuses of blood-vessels. The tubuli uriniferi, 
 the pelvis of the kidney, and the ureter, are lined by spheroidal 
 epithelium. Between the straight tubes in the Malpighian 
 pyramids, there have been discovered numerous smaller tubules, 
 named the looped tubes of Henle. These come off from the 
 straight tubes in the cortical portion, descend towards the apex of 
 the pyramid, where they form loops, and again ascend to terminate 
 in the Malpighian capsules. 
 
 The Malpighian capsules are situated in the cortical portion, 
 average about y^th of an inch in diameter, and are visible to the 
 naked eye as minute red points. 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, afferent vessel, which enters the 
 capsule opposite to the commencement of the 
 urinary tube. In the capsule the artery breaks 
 up into a coil of minute vessels, glomerulus, 
 and returns its blood by a vein (efferent vessel), 
 which emerges from the capsule close to where 
 the artery entered (fig. 112). Instead of leaving 
 ^ ne kidney, as in other organs, the vein forms a 
 c ' catsuit efferent vesse1 ' pl exus round the convolutions of the urinary 
 a. urinary tube. tube.f The purpose of this plexus appears to 
 
 be the secretion of the solid matter of the urine; while the Malpig- 
 hian body filters the watery part of the urine into the capsule, 
 and washes the mere solid part down the tube.| The coil of vessels 
 
 * ' Philosoph. Trans.' for 1842 ; part i. 
 
 f For a summary of the opinion held by various observers, respecting these Mal- 
 pighian corpuscles, consult a paper by E. Southej, M.D., ' St. Bartholomew's Hosp. 
 Reports,' vol. i. 1865. 
 
 J 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 portse, out of which the bile is elaborated in the liver ; 
 2. from the fact that in reptiles the urine is secreted from venous blood. 
 
 a Artery 
 
STRUCTURE OF THE SUPRA-RENAL CAPSULES. 487 
 
 in the capsule is surrounded by the epithelium lining the interior 
 of the capsule. 
 
 The renal artery enters the hilus between the pelvis -and the 
 renal vein. It shortly divides into four or five branches, which 
 pass outwards between the papillae, and then enter the cortical 
 portion between the pyramids. In this portion they ascend as far 
 as the bases of the pyramids, and then coursing- along their bases 
 they form arches between the cortical and medullary structure, 
 from which small vessels are given off, which pass to the Mal- 
 pighian capsules. 
 
 The nerves forming the renal plexus are derived from the 
 lesser splanchnic nerve and the solar plexus. The lymphatics, 
 consisting of a deep and a superficial set, pass to the lumbar 
 glands. 
 
 SUPBA-EENAL These bodies,'situated at the top of the kidneys, 
 
 CAPSULES. 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 a delicate fibrous stroma, in which 
 run parallel columns of cells 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 zone of cells arranged above and below them. The 
 columns are stated by some to be tubes having a distinct 
 lining membrane; by others, to be closed vesicles; by others, 
 to be cavities in the cortical portion. Small arteries are abun- 
 dantly 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 sometimes of a dark-brown colour, 
 
488 STEUCTURE OF THE STOMACH. 
 
 sometimes nearly white. It consists of a plexus of minute veins, 
 among which are numerous cells, some of which appear branched.* 
 The stroma is composed of areolar tissue, which forms a delicate 
 network throughout the central part. 
 
 The supra-renal capsules are well supplied with nerves derived 
 from the solar and renal plexuses of the sympathetic. Of late 
 years the minute structure and functions of the supra-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 discolouration 
 of the skin. Their precise function is still unknown. 
 
 STOMACH AND The alimentary canal is composed of four coats ; 
 
 INTESTINE. a serous, a muscular, a submucous, and a mucous. 
 
 First, is the serous or peritoneal coat, described at p. 379. 
 Secondly, under the serous is a muscular coat, upon which the 
 chief strength of the canal depends. It consists of two distinct 
 strata of plain muscular fibres ; the outer stratum is longitudinal, 
 the inner circular. 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 con- 
 tents to greater advantage. 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 in different parts, according to the functions 
 which it has to perform. 
 
 The stomach should be moderately distended 
 STOMACH. . 
 
 to see its size, which varies in different subjects 
 
 according to the habits of the individual. When distended, an 
 average stomach would be about ten or twelve inches in length 
 and four in width. The stomach forms a large bulge to the left 
 of the oesophagus, called the cardiac or splenic end : on the 
 right side, where the food passes out, it becomes small and con- 
 
 * Consult ' A Physiological Essay on the Thymus Gland,' by Simon : London, 
 1845. 
 
STRUCTURE OF THE STOMACH. 489 
 
 tracted, and is called the pyloric end. Just before the pylorus, 
 the stomach bulges into a pouch, called antrum pylori. Anato- 
 mists describe the stomach as having two borders and two sur- 
 faces. The upper border is concave, and called the lesser curve : 
 the lower border is convex, and called the greater curve. 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 internal 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. 
 The oblique fibres are scattered over the sides of the stomach, and 
 are most distinct at the entrance of the ossophagus, with the 
 well-marked circular fibres of which they are continuous. 
 
 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 mem- 
 brane is connected to the muscular layer by a distinct stratum of 
 areolar tissue, called the submucous coat. It permits the mus- 
 cular and mucous coats to move freely on each other, and serves 
 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 
 hexagonal pits or alveoli, giving it a honey-combed appearance. 
 The pits vary from the y^-g- to -^fa of an inch in 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 -^ of an inch long 
 and the -^-^ of an inch in diameter. In the cardiac end they are 
 
490 STEUCTUEE 0$ THE SMALL INTESTINE. 
 
 simple tubes, but, at the pyloric, 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 con- 
 tents, and disappear. Other glands pyloric are found near the 
 pyloric end of the stomach, and are probably mucous glands. There 
 are also glands more numerous than these, called peptic glands. 
 They are lined for a short distance with columnar epithelial cells, 
 which at the neck become spheroidal and granular, and are called 
 peptic cells ; towards the lower part or fundus of the gland the 
 cells are only found here and there, and cause a more or less bulging 
 of the basement membrane. 
 
 The mucous membrane of the stomach is lined by columnar 
 epithelium. 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. 
 
 SMALL The small intestine, consisting of the duodenum, 
 
 INTESTINE. jejunum, and ileum, forms a tube from sixteen to 
 
 twenty-six feet in length, according to the height of the individual. 
 The duodenum is about twelve fingers' breadth in length ; the 
 jejunum comprises two-fifths, the ileum three-fifths, of the remain- 
 ing part of the small intestine. As regards their external cha- 
 racter, the duodenum and jejunum are more vascular than the 
 ileum, and feel thicker in consequence of the peculiar arrangement 
 of their mucous membrane ; but there are no defined limits between 
 the different portions of the intestinal canal. Its peritoneal and 
 muscular coats are the same throughout. The muscular coat 
 consists of an outer longitudinal layer and an inner circular thicker 
 
STRUCTURE OP THE SMALL INTESTINE. 491 
 
 layer, which, however, becomes thinner towards the end of the ileum. 
 It is connected to the mucous membrane by the submucous coat. 
 Immediately beneath the mucous membrane there is a very thin 
 layer of non-striped muscular fibre, termed muscularis mucosce. 
 
 When the small intestine is cut open from the upper end, 
 we see that the mucous membrane is arranged in close transverse 
 folds, called valvulce conniventes. 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 distended. 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 opening of the biliary and pancreatic ducts, and are 
 most 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 intestine, 
 and 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 are 
 so numerous 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 
 a basement membrane. Each villus is furnished with an artery 
 which forms a network of inosculations in it, and then returns its 
 blood by a single vein. Down its middle runs a lacteal or absorb- 
 ing vessel, which commences in a closed end near the summit of 
 the villus, where it is surrounded by a layer of pale non-striped 
 muscular fibres proceeding from the muscularis mucosce. The 
 * Krause estimates the total number of villi at four millions. 
 
492 STRUCTURE OF THE SMALL INTESTINE. 
 
 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. 
 INTESTINAL There are four kinds of glands* in the small in- 
 
 GLANDS. testine, called the glands of Lieberkiihn, Brunner, 
 
 Peyer, and the solitary glands. The first and last are distributed 
 over the whole tract of the intestinal mucous membrane ; the other 
 two over particular parts. 
 
 The glands of LieberkuhnJ the most numerous of all, 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 -^ to -^ of a line, and about the J^ of 
 a line in diameter, and are lined with columnar epithelium. 
 
 The glands of Brunner \ are found only in the duodenum. 
 They are just visible to the naked eye, and may be seen by re- 
 moving the muscular coat. Their structure exactly resembles the 
 ' round compound glands of the mucous membrane of the mouth. 
 
 The glands of Peyer (glandulse agminatse) 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 mesen- 
 tery. 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, embedded in the sub-mucous 
 tissue. They are composed of masses of lymphoid tissue, of 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 
 
 * A satisfactory examination of the intestinal glands can be made only in speci- 
 mens quite recent, taken from young persons who have died suddenly, or from a 
 rapidly fatal disease. 
 
 f J. N. Lieberkiihn, 'Diss. de fabric, etactione villorum intestin. ten.,' 1782. 
 
 \ J. C. Brunner, ' Gland, duoden. seu pancreas secundarium,' 1715. 
 
 Peyer, ' De glandulis intestinorum,' 1682. These glands were first described by 
 Nehemiah Grew, in 1681. 
 
STRUCTURE OP THE LARGE INTESTINE. 493 
 
 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. They 
 diminish in number and size with old age. 
 
 The solitary glands are scattered over all parts of the small 
 and large intestines. They consist of the same lymphoid structure 
 as the glands of Peyer, and only differ from them in being solitary 
 instead of being aggregated into groups. 
 
 The lymphatics consist of two sets, those of the muscular 
 and those of the mucous coats; the latter receive those from the 
 villi, at the base of which they form a minute plexus, and, after 
 piercing the muscular coat, join with the former, which are 
 chiefly found between the longitudinal and the circular layers of 
 muscular fibres. 
 
 The nerves are derived from the superior mesenteric plexus, 
 and accompany the superior mesenteric artery and its branches, 
 between the layers of the mesentery ; after reaching the intestinal 
 walls the nerve-filaments separate from the arteries. They then 
 pierce the external longitudinal muscular fibres and form a very 
 minute gangliated plexus, Auerbach's plexus or plexus myen- 
 tericus, which distributes filaments to the muscular layer of the en- 
 tire intestinal canal. From this plexus numerous branches perforate 
 the internal circular muscular layer, and unite to form a largely 
 gangliated plexus, Meissner's plexus, in the submucous tissue. 
 The intermuscular plexus probably supplies the muscular coat and 
 regulates the peristaltic action of the bowel ; the submucous 
 plexus determines the calibre of the blood-vessels. 
 
 LABGE The principal external characters of the large 
 
 INTESTINE. intestine are that it is pouched or sacculated, and 
 
 that it has attached to it little pendulous portions of fat covered 
 by peritoneum, called appendices epiploicce. The pouches (sac- 
 culi) 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 circumference of the 
 bowel; another with the front part; a third with its concavity. If 
 
494 STEUCTUKE OF THE LAEGE INTESTINE. 
 
 at any. given part the three bands be divided, the pouches imme- 
 diately disappear. 
 
 In a colon moderately distended and dried, we observe that the 
 mucous membrane forms numerous ridges or incomplete septa 
 (see fig. 113): 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 
 
 FIG. 113. 
 
 1. Ileum. 
 
 2. Caecum or caput coli. 
 
 SECTION THROUGH THE JUNCTION OF THE LARGE AND SMALL INTESTINE, TO SHOW 
 THE ILIO-C.SCAL VALVE. 
 
 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 ani, 
 
 The mucous membrane of the large intestine differs consider- 
 ably from that of the small. There are neither valvulae conni- 
 
8TEUCTUBE OP THE LABGE INTESTINE. 495 
 
 ventes nor villi ; but the glands of Lieberkiihn and the lymphoid 
 follicles may be seen studding the mucous membrane. The 
 follicles 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 sur- 
 face as 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. 
 
 ILIO-CJECAL At the junction of the small with the large 
 
 VALVB. intestine the 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. The arrangement of the valve is best examined in a 
 dried preparation. The opening is a transverse fissure like a 
 button-hole ; and the two flaps are arranged like an upper and a 
 lower eyelid. The upper lid of the valve projects more than the 
 lower, so that the contents of the ileum drop naturally down into 
 the caput coli, where they are apt to collect and form hard lumps. 
 The flaps of the valve consist of mucous membrane and the cir- 
 cular fibres of the ileum. The longitudinal fibres of the ileum 
 are continued directly on to the caecum : if these be divided, the 
 ileum can be drawn out, and the valve disappears.* 
 
 FOLDS i THE In many subjects we observe that transverse or 
 
 RECTUM. oblique folds of the mucous membrane project 
 
 into 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.-f- 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 te occasion great pain and obstruction in defaecation. 
 
 * It is interesting to note that the surface of the valve, towards the ileum, 
 covered with villi ; not so the surface towards the large intestine. 
 
 t 'Dubli Hospital Reports,' yol. T. 
 
496 
 
 DISSECTION OF .THE LOWER EXTREMITY. 
 
 THE body having been placed on its back, the thigh should 
 be slightly flexed and abducted. An incision should be made 
 along the groin, from the anterior superior spine of the ilium 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. 
 
 SUPERFICIAL This fascia varies in thickness, according to 
 
 FASCIA. the condition of the body. Like other superficial 
 
 fasciae, 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, and is attached to Poupart's ligament. 
 
 The cutaneous vessels come from the femoral artery and are 
 three in number, the superficial epigastric, the su,perficial ex- 
 ternal pudic, and the superficial circumflexa ilii arteries : the first 
 ascends over Poupart's ligament to the abdomen (p. 355) ; the second 
 crosses inwards towards the pubes ; and the third passes outwards 
 to the ilium. 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. 
 
 SupEBFidAL These g^nds are easily recognised, by their 
 
 INGUINAL oval form and reddish-brown colour. There are 
 
 GLANDS. two sets : one set runs parallel to Poupart's liga- 
 
 ment, and receives the lymphatics from the penis, the scrotum, 
 the perineum, the anus, the buttock, the lower part of the ab- 
 
SUPERFICIAL VESSELS OF THE GROIN. 497 
 
 dominal wall, and the upper and outer aspect of the thigh ; the 
 other set lies along the saphena vein, and receives the lymphatics 
 from the foot, the leg, and the lower part of the thigh. This 
 explains why in cancer of the scrotum and syphilitic disease of 
 the penis the first set becomes enlarged ; and the second, in dis- 
 eases of the lower extremity. The lymphatic vessels which pass 
 to and from the glands are small, and may escape observation, 
 unless specially looked for. They all pass through the femoral 
 ring into the abdomen, and eventually empty themselves into the 
 receptaculum chyli. 
 
 The glands mentioned in the preceding paragraph are all 
 superficial. There are others, more deeply seated, close to the 
 great vessels of the thigh : these are much smaller, and sometimes 
 cannot be found. 
 
 SUPERFICIAL ^he superficial epigastric artery comes through 
 
 ARTERIES OF the fascia lata, half an inch below Poupart's 
 
 THE GROIN. ligament, supplies the inguinal glands, and anas- 
 
 .tomoses with the deep epigastric artery. Its further course is 
 described at p. 355. 
 
 The superficial circumfiexa ilii runs parallel to Poupart's' 
 ligament towards the crest of the ilium, and ends in the skin and 
 subcutaneous tissue. 
 
 The superficial external pudic comes through the saphenous 
 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 phimosis, since it runs along the penis to supply 
 the prepuce. Arising directly from so large an artery as the 
 femoral, it sometimes bleeds 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 branch.* There is 
 another pudic artery, called the deep or inferior external pudic : 
 
 * 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 deatfi of the patient, that 
 
 K K 
 
498 
 
 SUPERFICIAL VESSELS OF THE GROIN. 
 
 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 re- 
 flected, to expose the subcutaneous tissue over the whole of the 
 
 FIG. 114. 
 
 SUPERFICIAL VESSELS AND GLANDS OF THE GROIN. SAPHENOUS OPENING WITH THE 
 CBIBRIFORM FASCIA. 
 
 1\ Saphenous opening of the fascia lata. 
 
 2. Saphena vein. 
 
 3. Superficial epigastric artery. 
 
 4. Superficial circumflexa ilii artery. 
 
 5. Superficial pudic artery. 
 
 6. External abdominal ring. 
 
 7. Fascia lata of the thigh. 
 
 front of the thigh. In it will be found the cutaneous vessels and 
 nerves, which must be carefully dissected. 
 
 
 the ball had injured onJy 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. 
 
 .**. 
 
CUTANEOUS NERVES AND VEINS. 499 
 
 This is the chief subcutaneous vein of the lower 
 SAPHENA VEIN. ,.,,-, . . ,, ., ,. , , 
 
 limb. Its roots, arising on the inner side of the 
 
 foot, unite into a single trunk, which ascends in front of 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 open- 
 ing the saphenous opening in the fascia lata, to join the femoral 
 vein, immediately below the crural arch (fig. 114). 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 super- 
 ficial veins which accompany the arteries of the groin already 
 alluded to (p. 497). Like all subcutaneous veins, it is provided at 
 intervals with valves, chiefly where joined by other veins, to sup- 
 port the column of the blood. 
 
 CUTANEOUS The distribution of the cutaneous nerves- of the* 
 
 NEETES. thigh varies considerably, but they are- al-ways 
 
 found more abundantly - on the inner than on the outer aspect 
 of the thigh. The nerves are divided into external? middle, 
 and internal. All directly or indirectly proceed from the lumbar 
 plexus, and, perforating the fascia, divide 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 iliiirh. Here it divides 
 into two branches, an anterior and a posterior. The anterior 
 branch comes through the fascia lata about four inches below 
 Poupart's ligament and : can be traced down the outer side of the 
 thigh as far as the knee, giving off numerous branches. The 
 posterior branch, after coming through the fascia, divides into 
 filaments, which are distributed to the skin, over the nates and the 
 posterior part of the-thigh. : 
 
 b. The middle cutaneous nerves, one or two in number, are 
 given off by the anterior crural. They pass through the sartorius 
 about four inches below Poupart's ligament, - perforate the fascia 
 lata, and descend along the front and inner part of the thigh as 
 far as the knee, distributing branches on either side ; some of 
 which communicate with the long .saphenous nerve. In its course 
 
 K K 2 
 
500 FASCIA LATA. 
 
 along the front of the thigh it joins with the crural branch of the 
 genito crural and the internal cutaneous nerves. 
 
 c. The internal cutaneous nerve, also a branch of the anterior 
 crural, crosses obliquely over the femoral artery. It then divides 
 into branches which perforate the fascia Ma, and supply the skin 
 on the inner side of the thigh, over the patella, and the inner side 
 of the leg. Some- of these communicate with the middle cutaneous, 
 the long saphenous and the cutaneous branch of the obturator.* 
 
 d. The crural branch of the genito-crural nerve perforates the 
 fascia external to the femoral artery, immediately below Poupart's 
 ligament, 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. ' It 'also distributes a few filaments 
 to the femoral artery in its passage under the crural arch. 
 
 e. The ilio-inguinal nerve, after emerging from the external 
 abdominal ring, supplies the skin on the inner aspect of the thigh. 
 
 Remove the subcutaneous fat to examine the 
 I 1 AS CIA LATA. 
 
 fascia lata of the thigh. The use of this fascia is to 
 cover the muscles of- the thigh collectively, and to form separate 
 sheaths for each ; so that; -it not only keeps 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 according to the part in which it forms. 
 
 The fascia is not of equal strength all round the thigh. It is 
 comparatively thin on the inner side ; exceedingly thick and strong 
 down the outer side ; here, indeed, it has the appearance of a dense 
 expanded aponeurosis, strapping down the vastus externus muscle ; 
 and it certainly performs the office of a tendon, for it gives inser- 
 tion to two powerful muscles namely, the tensor fasciae femoris, 
 and the gluteus maximus (fig. 115). 
 
 The fascia lata is attached to the margin of the bones whicli 
 constitute the framework of the lower extremity. Beginning from 
 
 * It is important to note that one, or sometimes two, of these internal cutaneous 
 nerves cross the sheath of- the femoral arterj just where thesartorius begins to over- 
 lap it ; and therefore at the spot where it is usually tied. See diag., p. 511. 
 
SAPHENOUS OPENING. 
 
 501 
 
 FIG. 115. 
 
 above, its attachment can be traced from the posterior surface of 
 the sacrum and coccyx, along the crest of the ilium, thence along 
 the crural arch to the body of the pubes, and down the rami of the 
 pubes and ischium. Proceeding down the thigh, it penetrates, on 
 either side of the limb, to the linea aspera, forming what are called 
 the external and internal intermuscular septa, 
 which separate the extensor from the flexor 
 muscles. Below, it can be traced round the 
 knee-joint, and is particularly strong, especially 
 on the outer side, where it is attached to the 
 head of the tibia and fibula, and forms the inser- 
 tion of the tensor fascia? femoris. 
 
 There are numerous small , apertures in the 
 fascia, through' which the cutaneous nerves and 
 vessels are transmitted ; but the most important 
 one is the large opening the 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. 
 
 SAPHENOUS The saphenous opening is an 
 
 OPENING IN THE oval aperture in the fascia lata, 
 FASCIA LATA. immediately below the crural 
 
 arch, on the inner side of .the front of the thigh, 
 through which the saphena vein passes to join 
 the femoral. There is no definite border to the 
 saphenous opening until the fascia,- which covers FASCIA ON THE OUT- 
 the opening and blends with its margin, has been SIDB F T E THIGH. 
 removed. The term cribriform has been given i. Tensor fasciae femoris. 
 
 . .. 111 2- Glutens maximus. 
 
 to this tascia, because it is perforated with holes 3. Lower fibres of ditto. 
 
 4. Fascia lata. 
 
 tor the passage of the superficial vessels and 
 lymphatics. It is a thin covering over the saphenous opening, and 
 is prolonged from the outer edge of the opening over the sheath 
 CRIBRIFORM of the femoral vessels, and adheres on the inner 
 FASCIA. s j(j e to the fascia .lata, over the pectineus muscle. 
 
502 
 
 SAPHENOUS OPENING. 
 
 Some anatomists describe this fascia as a portion of the superficial 
 fascia ; others consider it as a thin prolongation of the fascia lata 
 itself across the opening. Its chief surgical importance is de- 
 rived 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 mil appear as represented in 
 fig. 116. 
 
 Keverting to the saphenous opening, we observe that it is 
 situated just below the crural arch, not far from the pubes ; that 
 it is oval with the long axis vertical, and about one inch and a half 
 
 1. Crural arch. 
 
 Saphenous opening of 
 the fascia lata. 
 
 Saphena vein. 
 4. Femoral *ein. 
 
 5. Gimbernat's ligament. 
 
 6. External abdominal 
 
 ring. 
 
 7. Position of the internal 
 
 ring in dotted out- 
 line. 
 
 DIAGRAM OF THE FEMORAL RING AN THE SAPHENOUS OPKNING. 
 
 (The arrow is introduced into the femoral ring.) 
 
 long and an inch broad. Its border on the inner side is not de- 
 fined ; for here the fascia lata ascends under the femoral vessels, 
 rand is continuous with the iliac fascia of the pelvis.* But the 
 outer or iliac border is clearly defined. 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 with a well- 
 defined border, and on being traced upwards becomes less well 
 
 * On the inner side of the femoral .vessels the pubic portion of the fascia is at- 
 .tached to the linea ilio-pectinea. 
 
PARTS CONCERNED IN FEMORAL HERNIA. 503 
 
 marked until it is gradually lost in the fascia on the inner side of 
 the opening. The upper horn, Hey's ligament,* arches over the 
 femoral vein, and then descending slightly is continued uninter- 
 ruptedly into Gimbernat's ligament Le. into that part of the crural 
 arch which is inserted into the lineailio-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 intro- 
 ducing the little ringer 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 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 limb ; 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 PARTS CONCERNED IN FEMORAL HERNIA. 
 
 The anatomy of the parts concerned in femoral hernia cannot 
 be thoroughly understood without the assistance of special dis- 
 sections. 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. 
 
 The different parts of the subject should be examined in the 
 following order : 
 
 a. The formation of the crural arch. 
 
 b. The arrangement of the parts as they pass under the arch. 
 
 c. The sheath of the femoral vessels. 
 
 * This upper horn is sometimes called ' Hey'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 at- 
 tached to it have received particular names, they are not, on that account, distinct and 
 separate ; but all are intimately connected, and portions merely of one continuous ex- 
 pansion. Thus all the parts are kept in a condition of mutual tension, which depends 
 very much on the position of the thigh. 
 
50 l< PARTS CONCERNED IN FEMORAL HERNIA. 
 
 d. The crural canal and ring. 
 
 e. The practical application of the subject. 
 
 POUPART'S The lower border of the aponeurosis of the 
 
 LIGAMENT OB external oblique muscle extends from the anterior 
 
 CRURAL ARCH. superior spine of the ilium to the spine of the 
 pubes, and forms, over the bony excavation beneath, the crural 
 arch or Pouparfs ligament. (It is marked by the dark line in 
 Sg. 116.) The direction of the arch is at first somewhat oblique, 
 but towards its inner half, becomes nearly horizontal. In conse- 
 quence of its intimate connection with the muscular fascia of the 
 thigh, the line of the arch describes a gentle curve with the con- 
 vexity downwards. The arch is attached to the spine of the pubes, 
 and also for some distance along the linea ilio-pectinea (fig. 116). 
 This additional attachment, called Gimbernatfs ligament,* is of 
 importance, for it is frequently the seat of stricture in femoral 
 hernia. 
 
 GIMBERNAT'S The best view of Gimbernat's ligament is ob- 
 
 LIOAMENT. tained from within the 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 through 
 Hej's ligament (fig. 116). Its length is from f of an inch to 1 
 inch ; but it is usually longer in the male than the female. 
 
 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. 
 
 ARRANGEMENT The crural arch transmits from the abdomen into 
 
 OF THE PARTS the thigh (proceeding in order from the outer 
 
 WHICH PASS UNDER s ide) the following objects, shown in fig. 117): 
 
 1. The external cutaneous nerve; 2. The iliacus 
 
 and psoas muscles, with the anterior crural nerve between them ; 
 
 "* 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. 
 
 505 
 
 3. The femoral artery and vein with the crural branch of the 
 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 space is left for the passage of the lymphatics : this 
 is called the crural or femoral ring. 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 separated from the 
 vein by a similar,. although a much weaker partition, and there is 
 
 FIG. 117. 
 
 External cutaneous n. . 
 
 Iliacus 
 
 Anterior crural n. . . . 
 
 Crural arch. 
 - External ring. 
 
 r Femoral ring. 
 
 Femoral vein and artery. 
 
 POSITION OF PARTS UNDER THE CRURAL ARCH (VERTICAL SECTIOS). 
 
 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 pro- 
 trusion between it and the muscles and vessels. This, coupled 
 with the close attachment of the fascia iliaca 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, on-become slock, then a rupture may de- 
 si-end in front of the vessels, or oven (though this is rare) on the outer side of the 
 artery. 
 
506 
 
 PARTS CONCERNED IN FEMORAL HERNIA. 
 
 SHEATH OF THE The femoral vessels descend beneath the crural 
 FEMORAL VESSELS, arch, enclosed in a funnel-shaped membranous 
 sheath. This sheath appears to be derived immediately 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 fascia iliaca to join the 
 fascia lata behind the femoral vessels, forms a funnel, with the 
 wide part uppermost, into which the femoral vessels enter. This 
 is the funnel-shaped sheath of the femoral vessels. 
 
 FIG. 118. 
 
 1, 1. Fascia transver- 
 salis. 
 
 2. Internal ring. 
 
 3. Crural arch re- 
 
 flee ted. 
 
 4. Sheath of the 
 
 moral vessels. 
 
 5. Saphena vein. 
 
 DIAGRAM OF THE 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 118. By this proceeding, 
 we expose the fascia transversalis descending 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 as low as the lower horn of the saphenous 
 opening, where it is gradually lost upon .the ordinary fibrous 
 investment of the femoral vessels. The outer part of the sheath 
 
PARTS CONCERNED IN FEMORAL HERNIA. 507 
 
 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 lymphatic vessels. 
 
 The sheath of the femoral vessels is divided into three com- 
 partments separated from each other by partitions : the outer 
 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 within it. 2. It constitutes, 
 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 inde- 
 pendent of it, as shown in fig. 118; 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 The hollow under the crural arch is completely 
 
 AND FEMORAL occupied by the structures before mentioned, ex- 
 RlNG - cept for a small space, called the crural canal, 
 
 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 Grimbernat'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 nng.* 
 
 The femoral ring is surrounded on all sides by unyielding 
 structures. This accounts for the little benefit afforded by the 
 warm bath in cases of strangulation. Sir W. Lawrence was in 
 
 * The femoral ring is naturally occupied by a little fat and cellular membrane, by 
 lymphatic vessels, and often by a small lymphatic gland, But we have never met with 
 anything deserving the name of a ' diaphragm ' or membranous septum, such as is 
 described by Cloquetas the ' septum crurale,' and is, surgically, of no importance. 
 
508 PARTS CONCERNED IN FEMORAL HERNIA. 
 
 the habit of saying that he never saw a strangulated femoral 
 hernia where the warm bath was of any avail. 
 
 PRACTICAL From what has been said, the student ought 
 
 APPLICATION ov now to understand 1, at what aperture a femoral 
 THE SUBJECT. hernia escapes from the abdomen ; 2, the course 
 
 which it takes, and its relations to the surrounding parts ; 3, the 
 proper mode of attempting 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 Gimbernat's ligament. Here is the mouth of 
 the hernial sac, or that part of it which communicates with the 
 abdomen. It descends for a short distance nearly perpendicu- 
 larly, 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 the 
 flexion of the thigh. Consequently, 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 The coverings of a femoral hernia are as fol- 
 
 A FEMORAL lows : It first protrudes before it the perito- 
 
 HERNIA. neum, technically called 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 
 
 * 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. 
 
TARTS CONCERNED IN FEMORAL HERNIA. 509 
 
 called the fascia propria. In front of this is the cribriform 
 fascia. Lastly, there is the subcutaneous tissue and skin. 
 
 SEAT OF The seat of stricture is usually at the femoral 
 
 STKICTURE. ring? and the position of the neighbouring blood- 
 
 vessels indicates that the proper direction in which to divide the 
 stricture is, either directly inwards, through Grimbernat's ligament, 
 as recommended by Sir W. Lawrence, or upwards through Key's 
 ligament, as recommended by Sir A. Cooper.* There is no risk 
 of wounding an artery, supposing the vessels to take their ordi- 
 nary course. But it occasionally happens (p. 441), that the obtu- 
 rator artery runs above (in the recumbent position) the femoral 
 ring ; in such a case, the neck of the sac would be encircled by 
 a large blood-vessel. t From the examination of two hundred 
 bodies, the chances are about seventy to one against this unfavour- 
 able 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 Grimbernat's ligament, 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 
 similar, 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 operate without the expectation of meeting 
 some peculiarity. 
 
 * 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. 
 
 f The museum of St. Bartholomew's Hospital contains two examples of double 
 femoral herniae in the male, with the obturator arising on each side from the epigas- 
 tric. 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 
 
510 SCAEPA'S TRIANGLE. 
 
 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, 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 ilium, 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 perpendicularly 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 connection with the fascia of the leg, which extends as low 
 as the internal malleolus. The broad insertion of this muscle 
 lies anterior to and covers the tendinous insertions of the gracilis 
 and semi-tendinosus, and between them is a bursa. A large bursa* 
 is interposed between the tendon and the internal lateral liga- 
 ment. The chief action of the muscle is to fix the pelvis steadily 
 on the thigh.f It crosses one leg over the other, as tailors sit 
 when at work. Its nerve comes from ,tke middle cutaneous branch 
 of the anterior cruraL 
 
 SCAEPA'S In consequence of the oblique direction of the 
 
 TBIANGLE. upper third 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 t-the triangle is called Scarpa's.^ 
 
 all these cases, however, the artery passed close by the bone, that is behind the sac, so 
 that it -would not have been injured in the operation for relief of strangulation. 
 
 * In persons, females especially, who are in the habit of riding, this bursa some- 
 times becomes enlarged. 
 
 f Hence the name given to it bySp'rgelius(De corporis hum. fabric.), 'Quern ego 
 sirtorium museulum vocare soleo, quod sartores eo maxime utuntur, dum crus cruri 
 inter consuendum imponunt.' 
 
 { So called in compliment to the Italian anatomist who first tied the femoral in it 
 for popliteal aneurysm. 
 
SCARPA 8 TRIANGLE. 
 
 511 
 
 The contents of this important space should be carefully dis- 
 played, 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 ilium ; the iliacus internus and psoas ; the 
 anterior crural nerve and its divisions, especially the long 
 saphenous nerve ; the common femoral artery with its two large 
 divisions, the superficial femoral and the profunda, which run 
 
 1. Sartorius. 
 
 2. Adductor longus. 
 
 3. External cutaneous 
 
 n. 
 
 4. Iliacus int:-rnus. 
 
 5. Anterior crural n. 
 
 6. Femoral artery. . 
 
 7. Femoral vein. 
 
 8. Pectineus. 
 
 9. Long saphenous n. 
 
 10. Internal cutaneous 
 n. 
 
 11. Nerve to vastus iu- 
 ternus. 
 
 12. Middle cutaneous n. 
 
 DIAGRAM OF SCARPA's TRIANGLE. 
 
 down nearly parallel to each other, the latter giving off the in- 
 ternal and external circumflex ; the femoral vein, joined by the 
 profunda vein and the internal saphena, and the pectineus muscle 
 with the deep external, pudic artery. 
 
 The triangle is important in a surgical^ point of view, since it 
 is in this space that the femoral artery is usually ligatured for 
 popliteal aneiirysm. Th 3 guide "to the artery is the inner border 
 of the sartorius. 'The situation at which this muscle crosses over 
 
512 ADDUCTOR MUSOTES. 
 
 the 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 beneath the 
 sartorius. The best way to find the inner border of the muscle 
 during life, is to make the patient put it in action. 
 
 ADDUCTOH A strong group of muscles, called the adductors, 
 
 MUSCLES. extends along the inner side of the thigh, from 
 
 the pelvis to the femur. Their two most important actions 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, at the same time rotating the 
 thigh externally. 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, ad- 
 ductor longus, pectineus, adductor l>revis, and adductor magnus. 
 The innermost is the gracilis ; to clean it properly, it should be 
 stretched by separating one thigh from the other. 
 
 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 round tendon which subsequently spreads 
 out, and is inserted into the inner side of the tibia below the 
 tubercle, immediately behind the sartorius and above the semi- 
 tendinous. The tendon plays over the internal lateral ligament 
 of the knee-joint, and there is a bursa to diminish friction. This 
 muscle assists in fixing the pelvis, and in adducting the thigh ; it 
 further helps to bend the knee. Its nerve comes from the anterior 
 division of the obturator. 
 
 ADDUCTOR This triangular muscle lies between the gracilis, 
 
 LONGUS. an d the pectineus, and arises by a round tendon 
 
 from the front of the body of the pubes below the crest. As it 
 descends, the muscle becomes broader, and is inserted into the 
 middle third of the inner margin of the linea aspera of the femur. 
 It forms with the sartorius the triangular space called Scarpa's 
 triangle, above described. It rests upon the adductor brevis and 
 
ADDUCTOR MUSCLES. 513 
 
 magnus, the profunda vessels and the obturator nerve. It is sup- 
 plied by the anterior division of the obturator nerve. 
 
 This muscle lies on the same plane, but external 
 to the adductor longus, from which it is separated 
 by a slight interval, in which may be seen the anterior division of 
 the obturator nerve. It arises from the triangular surface of the 
 pubes in front of the linea ilio-pectmea, and is inserted into the 
 upper part of the ridge leading from the lesser trochanter to the 
 linea aspera. It lies upon the adductor brevis, the obturator 
 vessels and nerve and the obturator externus. Its nerve comes 
 from the anterior craral, sometimes also from the obturator 
 (p. 410). 
 
 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 it, the pectineus and adductor longus must be 
 reflected from their origins. 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 and the pectineus ; the posterior runs 
 behind the adductor brevis, and supplies it as well as the obturator 
 externus, the adductor magnus, and the knee-joint. 
 
 ADDUCTOR This muscle arises from the front surface of the 
 
 BBEVIS< body of the pubes near the symphysis, and from 
 
 its descending ramus for about an inch ; it widens as it descends, 
 and is inserted behind the pectineus into the whole length of 
 the ridge leading from the lesser trochanter to the linea aspera. 
 Behind, it rests upon the posterior division of the obturator nerve, 
 and the adductor magnus. Its nerve is derived from the obtu- 
 rator. By reflecting it from its origin, the following muscle is 
 exposed.* 
 
 * 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. 
 
 L L 
 
514 ADDUCTOK MUSCLES. 
 
 ADDUCTOR This muscle arises from the lower part of the 
 
 MAGNUS. body of the pubes near the symphysis, from the 
 
 rami of the pubes and ischium, and from the tuberosity of 
 the ischium. Its fibres spread out, and are inserted, behind the 
 other adductors, into the lower part of the linea quadrati, into the 
 ridge leading from the great trochanter to the linea aspera, also 
 into the whole length of the linea aspera, and the ridge leading 
 from it to the inner condyle. The upper fibres pass transversely 
 outwards to their insertion, -while the lower fibres descend nearly 
 vertically. In front of the muscle are the adductor longus and 
 brevis, the vastus internus, the obturator nerve and artery and the 
 profunda artery ; above it are the internal circumflex artery, the 
 obturator externus, and the quadratus femoris ; behind it, the 
 biceps, semi-tendinous and semi-membranosus, the great ischiatic 
 nerve, and the -gluteus maximus. Its nerve comes from the 
 posterior division of the obturator. Observe that all the adductor 
 muscles are i inserted into the Jemur by flat tendons more or less 
 connected. 
 
 About the junction of the upper two-thirds with the lower 
 third of the thigh, the femoral artery passes through an oval, open- 
 ing in the tendon of the adductor magnus. 
 
 PSOAS MAGNUS These muscles have been fully described in the 
 
 AND ILIACUS dissection of the abdomen (p. 398). 
 
 INTERNUS. i"-i 
 
 TENSOR FASCIA This muscle is situated at the upper and outer 
 FEMORIS. part of the thigh. It arises from the external lip 
 
 of the crest of the ilium, close to the anterior superior spine. It 
 descends with a slight inclination backwards, and is inserted, at 
 the junction of the upper with the middle third of the thigh, 
 between two layers of the strong aponeurosis, generally described 
 as part of the fascia lata* (p. 500). Its chief use is to fix the pelvis 
 steadily on the thigh, and to rotate the thigh inwards ; in this last 
 action it co-operates with the anterior fibres of the gluteus medius, 
 with which it is almost inseparably connected. Anyone may con- 
 vince himself, of this by placing his hand on the hip, and rotating 
 
 * The deeper of these two layers runs up to be strongly connected with the ten- 
 don of the rectus and the front of the capsule of the hip-joint. 
 
EXTENSOR MUSCLES. 5J5 
 
 the thigh inwards. Both these muscles are supplied by the same 
 nerve the superior gluteal. 
 
 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 connective tissue.* With a little persever- 
 ance the aponeurosis can be traced to the linea aspera, the head of 
 the tibia, and the fibula, completely protecting the outer side of 
 the knee-joint. 
 
 EXTENSOR The powerful muscles occupying the front of the 
 
 MUSCLES OR thigh, and situated between the tensor fasciae on 
 
 QUADRICEPS the ou t e r side and the adductors on the inner, 
 
 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, re- 
 spectively, the crureus, the vastus intemus 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. 
 
 EECTUS This muscle arises from the pelvis by two strong 
 
 FEMORIS. tendons, which soon unite at an acute angle : one 
 
 round from the anterior inferior spine of the ilium, the other 
 flat from the rough surface of the ilium, just above the aceta- 
 bulum. The muscle descends along the front of the thigh, and is 
 inserted into the common extensor tendon, which will be pre- 
 sently examined. The structure of this muscle is remarkable. A 
 tendon runs down the centre, and the muscular fibres are inserted 
 on either side of it, like the vane on the shaft of a feather. Its 
 nerve comes from the anterior crural. 
 
 This mass of muscle invests like a cloak the 
 
 TliTCE!PS Ex~ 
 
 TENSOR. greater part of the front and sides of the shaft of 
 
 the femur; therefore the whole of it cannot be 
 
 * When this tissue becomes the seat of suppuration, the pus 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. 
 
 L L 2 
 
516 EXTENSOR MUSCLES. 
 
 seen without completely dissecting the thigh. It consists of an 
 outer, middle, and inner portion, called, respectively, the vastus 
 externus, the crureus, and the vastus internus. The vastus ex- 
 ternus arises by a 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 crureus and 
 the vastus internus arise (conjointly) from the upper three- 
 fourths of the front and inner surfaces of the shaft of the femur, 
 and from the entire length of the inner lip of the linea aspera. The 
 ultimate insertion of the several parts of the triceps is (through 
 the patella) into the common extensor tendon of the knee. 
 
 A few of the deeper fibres of the crureus 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- crureus. 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 connective tissue, there is nothing 
 to prevent the distension of the synovial membrane, in cases 
 of inflammation, to the extent of several inches above the patella. 
 COMMON Ex- The tendon of the rectus, gradually expanding, 
 
 TENSOR TENDON. becomes connected on its under surface with the 
 tendon of the crureus, 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 ligamentum 
 patellce, descends over the front of the knee-joint, and is inserted 
 into the rough part of 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 completely protected all round. The patella is a large sesamoid 
 bone, interposed to facilitate the play of the tendon over the con- 
 dyles 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 
 
EXTENSOR MUSCLES. 517 
 
 bursse. One is placed between the ligamentum patellae and the 
 smooth part of the tubercle of the tibia, the other between the 
 crureus and the lower part of the femur. This last is of consider- 
 able size. In early life it is, as a rule, distinct from the synovial 
 membrane of the knee-joint ; but after a few years a wide com- 
 munication frequently exists between them. 
 
 ACTION OF The extensor muscles of the thigh are among 
 
 THE EXTENSOE the most powerful in the body. Great power of 
 MUSCLES. extending the knee is one of the essential con- 
 
 ditions 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 contributes 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 power of the extensor 
 muscles than when the patella is broken by their sudden con- 
 traction ; an injury which sometimes happens when a man, 
 slipping backwards, makes a violent effort to recover his balance. 
 
 BTTBSA OVER The skin over the patella is exceedingly loose, 
 
 THE PATELLA. and in the 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 
 generally called the housemaid's bursa. The bursa is not seated 
 precisely over the patella, but extends some way down the liga- 
 mentum patellae; indeed, in some cases it is entirely confined to 
 this ligament. This corresponds with the position of the tumour 
 which the bursa occasions when enlarged. Generally speaking, 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 areolar tissue. 
 
518 COURSE AND RELATIONS OF FEMORAL ARTERY. 
 
 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. 
 
 c The femoral artery is a continuation of the 
 
 RELATIONS OF external iliac. Passing beneath the crural arch 
 THE FEMOKAL at a point midway between the spine of the ilium 
 
 and the symphysis pubis, it descends 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 
 indicated of the crural arch to the adductor tubercle on the internal 
 condyle corresponds with the course of the artery. Its distance 
 from the surface increases as it descends. Immediately 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 profunda vessels ; still 
 lower down it lies upon the adductor longus, and then upon the 
 adductor magnus. 
 
 That part of the artery which extends from the crural arch to 
 the giving off of the profunda, is called the common femoral 
 artery ; its continuation beyond the profunda is termed the super- 
 ficial femoral ; and it is the latter vessel which is ligatured for 
 aneurysm of the popliteal artery. 
 
 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, and the sheath of the femoral vessels. 
 About the middle third it is more deeply seated, and is covered 
 by the sartorius ; and lower down by a tendinous aponeurosis, 
 
HUNTER'S CANAL. 519 
 
 which stretches from the adductor longus and magnus over to the 
 vastus interims. This, which forms part of Hunter's canal, will be 
 examined presently. 
 
 At the crural arch the anterior crural nerve is placed on the 
 outer side of the artery (separated from it by a few fibres of the 
 psoas), and the femoral vein on the inner side : as the vein 
 descends, it gradually passes behind the artery. Artery and vein 
 lie close together, and are enclosed in a common sheath. 
 
 HUNTER'S In the middle third of the thigh, the femoral 
 
 CANAL. artery is contained in a tendinous canal* beneath 
 
 the sartorius, called Hunter's canal. This canal at its upper 
 part is rather indistinct ; but it gradually becomes stronger to- 
 wards the opening in the tendon of the ad- FIG. 120. 
 ductor 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 
 
 1 * SECTION THROUGH 
 
 an aponeurotic expansion thrown obliquely HUNTER'S CANAL. 
 across from the adductors to the vastus inter- * vastns internus. 
 
 2. Adductor longus. 
 
 nus, as shown in fig. 1 20. In a horizontal section 3. Aponeurosis thrown across 
 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 sides of the triangle always tight, and thereby prevent 
 any compression of the vessels. 
 
 Hunter's canal contains not only the femoral artery and vein, 
 but the internal saphenous nerve. The vein lies behind and to 
 the outer side ; the nerve crosses fcom the outer to the inner 
 side of the artery. 
 
 A ligature can be placed around the artery, in the upper third 
 of the thigh, with comparative facility; not so easily in the 
 middle third. The artery is tied .for an aneurysm of the popliteal, 
 
 * Called Hunter's canal, because it was -in this part of its course that John 
 Hunter first tied the femoral artery for aneurysm of the popliteal, in St. George's Hos- 
 pital, A.D. 1785. The particulars of this interesting caee-are published in the 'Trans, 
 for the Improvement of Med. and Chir. Knowledge.' 
 
520 PEOPUNDA FEMOEIS. 
 
 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 of the formation of a clot. An incision, 
 beginning about three inches, below the crural arch, should be 
 made about three inches long over the line of the artery. The 
 muscular fascia should be divided on a director to the same extent. 
 Then, by gently drawing aside the inner border of the sartorius, 
 the artery is seen enclosed in its sheath with the vein. An opening 
 should be made into the sheath, which must be carefully separated 
 from the artery to an extent sufficient to allow the passage of 
 the aneurysmal needle. The needle should be turned round the 
 artery from within outwards, great care being taken not to injure 
 the vein. The nerves to be avoided are the long saphenous, which 
 runs along the outer side of the artery, and the internal cuta- 
 neous which crosses obliquely over it. 
 
 Having already traced the superficial branches of the femoral 
 artery in the groin, namely, the superficial epigastric, the external 
 pudic, and the superficial circumflexa ilii (p. 497), we pass on- 
 now to the profunda. 
 
 PROFUNDA. The profunda^ the chief branch of the 
 
 ARTERY AND femoral, is the proper nutrient artery of the 
 
 BRANCHES. muscles of the thigh, and is by many considered 
 
 as a division, rather than a branch, of the common femoral 
 artery. It is given off from the outer and back part of the 
 femoral, from one and. a half to three 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 profuoda, for a short distance after its origin, lies 
 rather on "the -outer side of the femoral and on a deeper plane, 
 over the iliacus intern us : in this situation it might be mistaken 
 
 * 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 1 and 2 inches ;.in 9 this distance was exceeded; in 7 this distance was 
 
 . kss. 
 
BRANCHES OF PROFUNDA. 521 
 
 for the femoral itself indeed, such an error has occurred in 
 practice. It soon, however, gets behind the femoral, and lies 
 upon the pectineus, 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 and back 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 divides into 
 two branches : one the ascending supplies the muscles in its neighbour- 
 hood, namely, the pectineus, psoas, adductors, gracilis, and obturator ex- 
 ternus, anastomosing with the obturator artery ; the other tbe transverse 
 will be seen in the dissection of the back of the thigh, between the 
 adductor magnus and the quadratus femoris. This latter sometimes 
 gives off a small 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 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 the ilium, beneath the tensor fascise 
 and gluteus medius, supply these muscles, and inosculate with the termi- 
 nal branches of the gluteal artery. The transverse pass directly outwards 
 over the crureus, then enter the vastus externus, and get between the 
 muscle and the femur. They inosculate with the ischiatic, the internal 
 circumflex, the gluteal, and the perforating arteries. The descending, 
 one or more in number, of considerable size, run down between the 
 rectus and crureus, and supply both these muscles : one branch, larger 
 than the rest, runs down in the substance of the vastus externus, 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 four. The first passes through the adductor brevis and magnus, 
 and communicates with the internal circumflex and ischiatic arteries. 
 
522 
 
 ARTERIAL INOSCULATIONS. 
 
 The second, the largest, passes- through the tendons of the adductor brevis 
 and magnus, and usually furnishes the nutrient artery of the femur. The 
 third, passes through the tendon of the adductor magnus. The fourth, 
 or terminal branch, passes through the tendon of the adductor magnus, and 
 supplies the hamstring muscles, and inosculates with the perforating and 
 articular arteries. They not only supply the hamstring muscles namely, 
 
 FIG. 121. 
 
 1. Crural arch. 
 
 2. Internal iliac. 
 
 3. Superficial femoral. 
 
 4. Profunda. 
 
 5. Internal circumflex. 
 
 6. External circumflex. 
 
 7. First perforating. 
 
 8. Second ditto. 
 
 9. Third ditto. 
 
 10. Gluteal. 
 
 11. Obturator. 
 
 12. Ischiatic. 
 
 13. Anastomotica magna. 
 
 PLAN OF THE INOSCULATIONS OF THE CIRCUMFLEX ARTERIES. 
 
 the biceps, semitendinosus, and semimembranosus but, the vastus ex- 
 ternus and even the gluteus maximus. The perforating arteries inoscu- 
 late with one another, with the internal and external circumflex, and with 
 the ischiatic arteries. 
 
 ARTERIAL IN- 
 OSCULATIONS. 
 
 If the common femoral were tied above the 
 origin of the profunda, how would the circulation 
 
ANOJEEIOE CRURAL NERVE. 523 
 
 be carried on ? The ascending branch of the external circumflex 
 communicates with the gluteal and the circumflex iliac ; the in- 
 ternal circumflex communicates with the obturator and ischiatic 
 (see fig. 121). Again how is the circulation maintained when 
 the superficial femoral is tied beloiv the profunda ? The descend- 
 ing branch of the external circumflex and the perforating branches 
 of the profunda communicate with the articular branches of the 
 popliteal and the tibial recurrent.* 
 
 The anastomotica magna arises from the femoral artery just 
 before it leaves its tendinous canal. It emerges through the 
 canal, and runs in front of the tendon of" the adductor magnus, in 
 company with the long saphenous nerve to the inner side of the 
 knee. Here it divides into two branches : one, the superficial, 
 accompanies the saphenous nerve, and is subsequently distributed 
 to the skin ; the other, the external?, ramifies over the capsule and 
 communicates with the other articular arteries.f 
 
 ANTEHIOR The anterior crural nerve is the largest branch 
 
 CKUBAL NEKVE. o f the lumbar plexus (p. 409). It comes from the 
 third and fourth lumbar nerves, sometimes also from the second. 
 It passes beneath the crural arch, lying in the groove between 
 the iliacus interims 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 extensor 
 muscles of the thigh. The cutaneous branches, already described 
 (p. 499), 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 fe- 
 moral 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 
 
 * Read the account of the dissection of an aneurysmal limb by Sir A. Cooper, 
 ' Med. Chir. Trans.' vol. ii. 
 
 f In its course down the thigh the femoral artery gives off several small branches 
 to 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 network of vessels on the surface of that bone. 
 
524 OBTURATOR NERVE. 
 
 runs in company with the anastomotica 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 com- 
 municates beneath the fascia lata with the internal cutaneous and obtu- 
 rator 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. 
 
 The muscular branches are to be traced to the sartorius, rectus, crureus, 
 and subcrureus ; the branch to the vastus externus accompanies the de- 
 scending branch of the external circumflex artery, and sends a filament 
 to the knee-joint ; that to the vastus in ternus runs parallel with, but 
 external to, the long saphenous nerve, and supplies filaments to the 
 knee-joint. One branch passes under the femoral artery and vein to enter 
 the anterior surface of the pectineus. 
 
 The obturator nerve, also a branch of the lumbar plexus 
 (p. 409), supplies the adductor muscles. It enters the thigh 
 through the upper part of the obturator foramen above the corre- 
 sponding artery, and immediately divides into two branches, of 
 which one passes in front of, the other behind, the adductor brevis. 
 The anterior branch subdivides for the supply of the gracilis, the 
 adductor longus, and sometimes the adductor brevis and pecti- 
 neus ; it, moreover, sends a filament to the hip-joint, another to the 
 femoral artery ; and a third forms a plexiform communication at the 
 lower border of the adductor longus with the internal cutaneous 
 and long saphenous nerves. The posterior -branch supplies the 
 obturator externus, the adductor brevis and magnus. In some 
 bodies you can trace a filament of this 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, an internal and an external, which 
 form a circle round the obturator membrane. These supply 
 the external obturator and adductors of the thigh, and inosculate 
 
DISSECTION OF THE FRONT OF THE LEG. 525 
 
 with the internal circumflex artery (p. 522). The latter branch 
 sometimes gives off the small artery to the ligamentum teres of 
 the hip-joint. 
 
 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 bases of the toes. Eeflect the skin from the 
 front and sides of the leg and foot. 
 
 CUTANEOUS Having traced the internal saphena vein 
 
 VEIWSAND (p. 499) to the inner side of the knee, follow 
 
 NEEVES. it down the inner side of the leg, in front of the 
 
 inner ankle* to the dorsum of the foot. On the dorsum of the 
 foot notice that the principal veins form an arch, with the con- 
 vexity 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. 
 
 LONG SAPHE- The skin on the inner side of the leg is supplied 
 
 NOUS NERVE. by the long or internal saphenous nerve (p. 523). 
 
 It becomes subcutaneous on the inner side of the knee, between 
 the gracilis and sartorius. Here it meets the saphena vein, and 
 accompanies it down the leg, distributing its branches on either 
 side, till it is finally lost on the inner side of the foot and 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. 
 It pierces the sartorius close to the knee, and forms with 
 branches from the internal, middle, and external cutaneous nerves, 
 the plexus patellae. 
 
 * The French commonly bleed from the internal saphena vein as it crosses over 
 the inner ankle, this being a convenient and safe place for venesection. 
 
526 MUSCULAR FASCIA AND ANNULAR LIGAMENTS. 
 
 The internal cutaneous nerve supplies the skin of the upper 
 and inner aspect of the leg, and joins the internal saphenous 
 nerve. 
 
 The skin on the front and outer parts 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 its external cutaneous 
 branch as follows : 
 
 EXTERNAL Cu- This branch of the peroneal irerve comes 
 TANEOUS BRANCH through the fascia about the lower third of 
 OF THE PEEONEAL ^ e outer side of the leg; and descending over 
 the front of the ankle, divides into two. Trace 
 them, and you will find that the inner and smaller supplies the 
 inner side of the great toe, and the contiguous sides of the 
 second and third toes ; towards its termination it communicates 
 with the long saphenous and anterior tibial nerves. The outer 
 distributes branches to the outer side of the third toe, both sides 
 of the fourth, and the inner side of the fifth toe, and joins the 
 short (or external) saphenous nerve. 
 
 The outside of the little toe is supplied by the short saphe- 
 nous nerve, which runs behind the outer ankle with the corre- 
 sponding vein. 
 
 The contiguous sides of the great and second toes are supplied 
 by the termination of the anterior tibial nerve.* 
 
 -, This is remarkably thick and strong. Besides 
 
 FASCIA AND AN- its general purpose of forming sheaths for the 
 NUI.AK LIGA- muscles, and straps for the tendons, it gives origin, 
 
 MENTS. ag i n the forearm, to muscular fibres ; so that it 
 
 cannot be removed 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 
 
 * Such is the most common distribution of the nerves to the upper surface of the 
 toes. But deviations from this arrangement are frequent. 
 
MUSCLES ON THE FRONT OF THE LEG. 527 
 
 becomes stronger as it approaches the ankle, to form the liga- 
 ments which confine the tendons in this situation. Of these liga- 
 ments, called annular, there are three, as follows : 
 
 a. The anterior annular extends obliquely across the front of 
 the ankle-joint, and confines the extensor tendons of the ankle 
 and toes. It consists of two converging straps, which join, and are 
 continued on as a common band, like the letter H< placed trans- 
 versely. The common band is attached to the external malleolus, 
 cuboid and os calcis : it is continued horizontally inwards, and in 
 front of the ankle splits into two fasciculi ; the upper is attached 
 to the tibia ; the lower into the scaphoid and internal cunei- 
 form. It is the strain of this ligament which occasions the pain 
 in sprains of the ankle. You will see presently that it makes a 
 pulley for the extensor longus digitorum. 
 
 b. The external annular 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 annular is ill defined, and extends from the 
 inner malleolus to the os calcis, and binds down the flexor tendons 
 of the foot and toes. 
 
 Eemove the fascia, leaving enough of the annular ligaments to 
 retain the tendons in their places. 
 
 MUSCLES ON The muscles on the front of the leg are: 1, 
 
 THE FHONT OF the tibialis anticus ; 2, the extensor longus digi- 
 torum and peroneus tertius ; 3, the extensor 
 proprius pollicis. 
 
 TIBIALIS The tibialis anticus arises from the external 
 
 ANTICUS. tuberosity and the upper two-thirds of the outer 
 
 side of the tibia, from the interosseous membrane, from the 
 fascia which covers it, and from that which separates it from the 
 next muscle. About the lower third of the leg the fibres termi- 
 nate 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 
 synovial membrane, which lines the sheath of the tendon beneath 
 
528 MUSCLES ON THE FEONT OF THE LEG. 
 
 the anterior annular ligament, accompanies it to within an inch 
 of its insertion ; 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 anterior tibial. 
 
 EXTENSOR This muscle lies along the fibular side of the 
 
 LONGUS DIGI- preceding. It arises from the external tuberosity 
 TOEUM. ^ e tjkj a? f rom the upper three-fourths of the 
 
 inner surface of the fibula, from the interosseous membrane, from 
 the fascia and the intermuscular septa. 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 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 ex- 
 tensor 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. 329). Its nerve comes from the anterior tibial. 
 
 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 ten- 
 don is facilitated by a synovial membrane, which is prolonged for 
 a short distance along each of its four divisions. Besides its chief 
 action, this muscle extends the ankle-joint.f 
 
 PERONEUS This appears to be a portion of the preceding. 
 
 TEHTIUS. it s fibres arise from the lower part of the inner 
 
 surface of the shaft of the fibula, the interosseous membrane, and 
 the intermuscular septum, and terminate on their tendon-like barbs 
 
 * It is generally necessary to divide this tendon in distortion of the foot inwards, 
 called talipes varus. 
 
 f There is often a large Imrsa between the tendon of the extensor longus digi- 
 torum and the outer end of the astragalus. This bursa sometimes communicates 
 with the joint of the head of the astragalus. 
 
ANTERIOR TIBIAL ARTERY. 529 
 
 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 th use of these muscles are obliged 
 to drag the foot along the ground, or to swing the entire limb 
 outwards, in walking. 
 
 EXTENSOR This muscle lies partly concealed between the 
 
 PROPRITTS tibialis anticus and the extensor longus digitorum. 
 
 POLLICIS. j ar i ses from rather more than the middle third 
 
 of the inner surface of the fibula, and from the interosseous mem- 
 brane. The fibres terminate in a penniform manner on the tendon, 
 which runs over the ankle, between the tendons of the tibialis 
 anticus and the extensor communis 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 neces- 
 sary to separate them from each other : this is easily done by 
 proceeding from the ankle towards the knee. 
 
 COURSE AND '-Th 6 anterior tibial artery is one of the two 
 
 RELATIONS OF THE branches into which the popliteal divides at the 
 ANTERIOR TIBIAL lower border of the popliteus. It comes at first 
 horizontally forward about 1 inches below the 
 head of the fibula, above the interosseous membrane, 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 indicate its 
 
 M M 
 
530 ANTERIOR TIBIAL AETERY. 
 
 course. In the upper third of the leg it lies deeply between the 
 tibialis anticus and the. extensor longus digitorum ; in the lower two- 
 thirds, between the tibialis anticus and the extensor proprius pollicis. 
 In front of the ankle the artery is crossed by the extensor proprius 
 pollicis, and lies between the tendon of this muscle and the inner 
 tendon of the extensor longus digitorum. 
 
 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 each side, which 
 communicate at intervals by cross branches. 
 
 The branches of the anterior tibial are as follows : 
 
 a. The recurrent branch ascends close by the outer side of the head 
 of the tibia, through the tibialis anticus, to the front of the knee-joint, 
 where it inosculates with the other articula* arteries derived from the 
 popliteal. 
 
 b. Irregular muscular branches, in its course down the leg. 
 
 c. The malleolar branches, external and internal, ramify over the 
 ankle : the external, descending beneath the tendon of the extensor longas 
 digitorum, ramifies on the external malleolus, inosculating with the 
 anterior peroneal and the tarsal arteries ; the internal passes beneath 
 the tibialis anticus, and anastomoses with the posterior tibial. They 
 supply the joint, the articular ends of the bones, and the sheaths of the 
 tendons around them. 
 
 EXTENSOR This muscle is situated on the dorsum of the 
 
 BREVIS DIGI- foot, beneath the long extensor tendons of the toes. 
 
 It arises from the outer part of the os calcis, from 
 the ligament uniting this bone to the astragalus, and from the 
 anterior annular ligament. The fibres run obliquely over the 
 foot, and terminate in four tendons, which pass forwards to the 
 four inner toes. The inner one is inserted by an expanded 
 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 in- 
 serted with them into the second and ungual phalanges. 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. 
 
PEKONEI MUSCLES. 531 
 
 This artery, the continuation of the anterior 
 AETEEY OF THE tibial, runs over the instep to the interval between 
 the first and second metatarsal bones, where it 
 sinks into the sole and joins the deep plantar arch. On the 
 dorsum 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 bre vis digitorum towards the outside of the foot, supplies 
 the bones and joints of the tarsus ; and inosculates with the external 
 malleolar, the peroneal, the metatarsal,- and the external plantar arteries. 
 
 b. The metatarsal branch generally runs towards the outside of the 
 foot, beneath the short extensor tendons, near the bases of the metatarsal 
 bones, and gives off the three outer interosseous arteries. These pass 
 forwards over the corresponding interosseous muscle's, supply them, and 
 then subdivide to supply the contiguous sides of the upper surfaces of 
 the toes. They communicate by perforating branches with the plantar 
 arteries at each end of the interosseous spaces. 
 
 c. The dorsalis hallucis is, strictly speaking, the artery of the first 
 interosseous space. It comes from the dorsal artery of the foot just before 
 this sinks into the sole, and runs forwards to supply digital branches to 
 the sides of the great toe, and the inner side of the second toe. 
 
 PEEOKEI These muscles are situated on the outer side ot 
 
 MUSCLES. the fibula, and are named, respectively, peroneus 
 
 longus and brevis. 
 
 PEBONEUS This arises from the outer surface of the fibula 
 
 LONGUS. along its upper two-thirds, from the fascia and 
 
 the intermuscular septa. The fibres terminate in a penniform 
 manner upon a tendon, which runs through a groove behind the 
 external malleolus, 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 sole. It crosses the sole obliquely forwards and in- 
 wards, 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 
 
 W M 2 
 
532 PERONEI MUSCLES. 
 
 membrane. In removing the metatarsal bone of the great toe, if 
 possible, leave the insertion of this tendon. Its nerve comes from 
 the peroneal. 
 
 PERONEUS This muscle lies beneath the preceding. It 
 
 BKETIS - arises from about the middle third of the outer 
 
 surface of the fibula, internal to the preceding muscle, and from 
 the intermuscular septa. It terminates on a tendon which 
 runs behind the external malleolus, 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 peroneal. 
 
 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 A the body 
 from falling on the opposite side, as when we balance ourselves on 
 one leg. 
 
 PERONEAL Near the inner side of the tendon of the biceps 
 
 OR MUSCULO-CU- flexor of the leg, is a large nerve, the external popli- 
 TANEOUS NERVE. t eal or peroneal, a branch of the great ischiatic. By 
 reflecting the upper part of 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 follows : 
 1. 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 and 
 supplies the muscles between which it runs, namely the tibialis 
 anticus, extensor longus digitorum, extensor proprius pollicis and 
 peroneus tertius : also the extensor brevis digitorum ; 3. The exter- 
 nal-cutaneous (p. 526), which comes through the fascia between the 
 
 * 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 
 below the ridge. 
 
 f In distortion of the foot outwards, called talipes valgus, it is generally neces- 
 sary to divide the tendons of the peronei. 
 
GLUTEAL REGION. 533 
 
 peroneus longus and the extensor longus digitorum ; 4. Branches, 
 which supply the peronei (longus and brevis) muscles. 
 
 If, then, the peroneal nerve were divided in the popliteal space, 
 the result would be paralysis of the tibialis anticus, the extensors 
 of the toes long and short and all the peronei. 
 
 DISSECTION OF THE GLUTEAL KEGION. 
 
 The body having been placed on its face, the pelvis is to be 
 raised to such a height by blocks placed beneath it, that the lower 
 extremities hang down over the end of the table. Then 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 direction along the crest of the 
 ilium. 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. 
 A large bursa is often formed between the cushion and the bone. 
 
 CUTANEOUS These are derived from several sources. The 
 
 NERVES. posterior divisions of ihe first and second lumbar 
 
 nerves descend over the crest of the ilium, near the origin of the 
 erector spinse, to supply the skin over the gluteus maximus as far 
 as the great trochanter. Internal to these, are the posterior 
 branches of the three upper 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 
 posterior to it, the iliac branch of the ilio-hypogastric. Other 
 cutaneous nerves ascend from below ; they are branches of the 
 lesser ischiatic, and proceed from beneath the lower border of the 
 gluteus maximus. Lastly, some branches from the external 
 cutaneous nerve of the thigh are seen on the outer side of 
 this region. 
 
 GLUTEAL Three powerful muscles are situated in the 
 
 MUSCLES. region of the buttock, one above the other, named, 
 
 according to their size, the gluteus maximus, medius, and minimus. 
 
534 GLUTEAL REGION. 
 
 The fascia covering the gluteus maximus is comparatively thin, 
 posteriorly, where it is attached to the sacrum, coccyx, and ilium ; 
 but anteriorly it is very dense and glistening, and gives origin to 
 the fibres of the gluteus medius, and lower down becomes con- 
 tinuous with the fascia lata. 
 
 GLUTEUS This is the largest muscle of the body, and is 
 
 MAXIMUS. covered by a fascia, 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 ilium, and from the rough surface below it, 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 
 aponeurosis which plays over the great trochanter, and joins the 
 fascia lata on the outside of the thigh (p. 500); the remaining 
 third is inserted into the femur, along the ridge (gluteal) leading 
 from the linea aspera to the base of 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 
 propels the body in walking, running or leaping, and rotates the 
 thigh outwards. It is supplied with blood by the gluteal and 
 ischiatic arteries ; with nerves from the lesser ischiatic, and the 
 sacral plexus. 
 
 WHAT is SEEN ^^ e gluteus maximus should be reflected from 
 
 BENEATH. THE its origin. The best way is to begin at the front 
 
 GLUTEOS MAXI- border, which overlaps the gluteus medius. The 
 .dissection is difficult, and he who undertakes it for 
 thejffirst- time, is almost sure to injure the subjacent parts. The 
 numerous vessels which enter its under surface must be divided 
 before the muscle can be reflected. This having been accom- 
 plished, the following objects will be exposed : 
 
 The muscle covering the ilium is the gluteus medius. At the* 
 posterior border of this are the several objects which emerge from 
 the pelvis through the great ischiatic notch namely, the pyri- 
 
GLUTEAL REGION. 535 
 
 formis muscle, above which is the trunk of the gluteal vessels 
 and nerve, and, below which, are the greater and lesser ischiatic 
 nerves, the arteria comes nervi ischiatici, the long pudendal 
 nerve, the ischiatic vessels, the pudic vessels and nerve, and the 
 nerve to the obturator internus. Coming through the lesser 
 ischiatic notch, is the tendon of the obturator internus, and 
 attached to it are the gemelli muscles, one above, the other below 
 it. Extending from the tuber ischii transversely 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 semi- 
 membranosus, biceps, semitendinosus, and of the adductor 
 magnus, from the tuber ischii, are also seen ; as well as the great 
 sacro-ischiatic ligament, which passes upwards to the sacrum, and is 
 pierced by the coccygeal branch of the ischiatic artery. The great 
 trochanter is exposed, together with a small portion of the vastus 
 externus ; and where the tendon of the glutens maximus plays 
 over the trochanter major, there is a large bursa, simple or multi- 
 locular. Lastly, the side of the sacrum, the coccyx, part of the 
 crest of the ilium, the tuberosity of the ischium, and the coccygeus 
 muscle are brought into view. 
 
 GLUTEUS This muscle arises from the surface of the 
 
 MEDIUS. ilium, between 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. Between its insertion 
 and the bone is a bursa. 
 
 Keflect the gluteus medius to see the third gluteal muscle. 
 The line of separation between them is marked by a large branch 
 of the gluteal artery. 
 
 GLUTEUS This muscle arises from the surface of the 
 
 MINIMUS. ilium below the 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 tro- 
 chanter, a bursa being interposed. This muscle and the pre- 
 
536 GLUTEAL REGION. 
 
 ceding are supplied by the superior gluteal nerve, a branch of the 
 lumbo-sacral. 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 ilium, 
 they are abductors of the thigh. The anterior fibres of the glutens 
 medius co-operate with the tensor fasciae in rotating the thigh 
 inwards. 
 
 GLUTEAL The gluteal artery is the largest branch of the 
 
 VESSELS AND internal iliac (p. 441). Emerging from the 
 
 NEKTES. pelvis through the great ischiatic foramen be- 
 
 tween the pyriformis and the gluteus medius, it divides into large 
 branches for the supply of the gluteal muscles. Of these, the 
 more superficial proceed forwards between the gluteus maximus 
 and medius, both of which they supply, and eventually anastomose 
 with the posterior sacral and ischiatic arteries ; others, deeper, 
 run in curves between the gluteus medius and minimus, towards 
 the anterior part of the ilium. Many of them inosculate with 
 branches of the external circumflex, the deep circumflexa ilii, and 
 the ischiatic arteries. 
 
 The nerve which accompanies the gluteal artery is a branch of 
 the lumbo-sacral nerve (p. 445). It subdivides to supply the 
 gluteus medius and minimus, and the tensor fasciae ; in some 
 subjects it sends a branch to the gluteus maximus ; but this 
 muscle is chiefly supplied by the lesser ischiatic nerve. 
 
 A surgeon ought to be able to cut down and tie the gluteal 
 artery as it emerges from the pelvis. The following is the best 
 rule for finding it : * 
 
 Draw a line from the posterior superior spine of the ilium to 
 the trochanter major, rotated inwards. The junction of the upper 
 with the middle third of this line lies over the artery as it emerges 
 from the upper border of the great ischiatic notch. 
 
 Now examine the series of muscles which rotate the thigh 
 outwards namely, the pyriformis, the obturator internus, the 
 gemelli, the quadratus femoris, and the obturator externus. 
 
 * The operation of tying the gluteal artery was first performed by John Bell. See 
 h's 'Principles of Surgery,' vol. i. p. 421. 
 
GLUTEAL REGION. 537 
 
 This muscle lies immediately below and parallel 
 to the lower fibres of the gluteus medius. It 
 arises by three fleshy fasciculi from the second, third, and fourth 
 segments of the front surface of the sacrum between the foramina 
 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. 
 
 OBTURATOH This muscle, of which little more than the 
 
 INTERNUS. tendon can be seen at present, arises within the 
 
 pelvis, from the ischium between the great ischiatic notch and 
 the obturator foramen, and superiorly as high as the brim of 
 the pelvis, from the obturator membrane, and slightly also from 
 the obturator fascia. The fibres terminate on four tendons 
 which converge towards the lesser ischiatic notch, pass round it 
 as over a pulley, and then uniting into one, are inserted into 
 the top of the great trochanter, close to the digital fossa. Divide 
 the tendon about three inches from its insertion, to see the four 
 tendons which play over the smooth cartilaginous surface. There 
 is a large synovial bursa to diminish friction. The nerve of this 
 muscle comes from the sacral plexus ; sometimes from the pudic 
 nerve. 
 
 GEMELLI These muscles are accessory to the obturator 
 
 internus, 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 and back 
 part of the tuberosity. Their fibres are inserted into the tendon 
 of the obturator internus. Both muscles derive their nerves from 
 the sacral plexus. ; ,' 
 
 QUADRATUS This muscle ai4ses from the ridge on the outer 
 
 part of the tuber ischii. Its fibres run horizontally 
 outwards, and are inserted into the back of the great trochanter, 
 into the greater part of the linea quadrati. The lower border of 
 the quadratus femoris runs parallel with the upper edge of the 
 adductor magnus ; in fact, it lies on the same plane. Between 
 these muscles is generally seen a terminal branch of the internal 
 
538 
 
 GLDTEAL REGION. 
 
 circumflex artery. Its nerve comes from the sacral plexus, and 
 enters its deep surface. 
 
 OBTUHATOB To see this muscle reflect the quadratus femoris. 
 
 EXTERNUS. It arises from the outer surface of the os pubis, 
 
 from the front surface of the ramus of the pubes and ischium, and 
 from the obturator membrane. The fibres converge to a tendon 
 
 FIG. 122. 
 
 12. N. of pyrifomis. 
 
 13. N. of gemellus superior. 
 
 14. N. of gemellus inferior. 
 
 15. N. of quadratus femoiip. 
 
 16. N. of gluteus 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 gluteal n. 
 
 7. Great ischiatic n. 
 
 8. Lesser ischiatic n. 
 
 9. Pudic n. 
 
 10. N. of obturator internus. 
 
 11. N. of levatorani. 
 
 PLAN OF THB SACEAL PLEXUS AND BRANCHES. 
 
 which runs horizontally outwards over a groove in the ischium, 
 and i? inserted into the deepest part of the digital fossa below the 
 gemellus inferior. Its nerve is a branch of the posterior division 
 of the obturator (p. 524). 
 
 GREAT ISCHI- This large nerve is formed by the union of the 
 
 ATIC NERVE. l as t lumbar and four upper sacral nerves (fig. 122), 
 
 and supplies all the flexor muscles of the lower extremity, and the 
 extensors of the foot. 
 
GLUTEAL REGION. 
 
 539 
 
 Emerging from the pelvis through the great sacro-ischiatic 
 foramen below the pyriformis, it descends over the external rotator 
 muscles of the thigh, along the interval between the tuber ischii and 
 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 upon the adductor magnus, 
 parallel with the great sacro-ischiatic ligament, and below the 
 middle of the thigh divides into the internal popliteal and the 
 peroneal (or external popliteal). It is accompanied by a branch 
 
 FIG. 123. 
 
 1. Gluteus medius. 
 
 2. Pyriformis. 
 
 3. Lesser sciatic nerve. 
 
 4. Obturator interims, 
 
 with the two gemelli. 
 
 5. Coccygens. 
 
 6. Great sciatic nerve. 
 
 7. Quadratus femoris. 
 
 8. Gluteus maximus. 
 
 9. The semitendinosus 
 
 and biceps. 
 
 10. Adductor magnus. 
 
 DEEP MUSCLES OF THE GLUTEAL REGION. 
 
 of the ischiatic artery, called the comes nervi ischiatici.* The 
 nerve distributes branches to the hamstring muscles and the 
 adductor magnus, and sends a small branch to the hip-joint which 
 pierces the posterior part of the capsular ligament. 
 
 LESSER This comes from the lower part of the sacral 
 
 ISCHIATIC NEEVE. plexus. It leaves the pelvis with the greater 
 
 * 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 in the Museum 
 of the Royal College of Surgeons a preparation in which the femoral was tied by John 
 Hunter fifty years before the man's death. 
 
540 
 
 GLUTEAL REGION. 
 
 ischiatic nerve, but on the inner side of it, and in company with 
 the ischiatic artery. The muscular branches which it gives off 
 are one or more inferior gluteal which enter the under surface 
 of the gluteus maximus. All its other branches are cutaneous. 
 One external turns round the lower border of the gluteus maximus, 
 and supplies the skin of the buttock. Another, the inferior or long 
 pudendal (p. 419), turns inwards towards the perineum, to supply 
 the skin of that region and the scrotum. The continued trunk runs 
 
 FIG. 124. 
 
 1. Gluteal artery 
 
 and nerve. 
 
 2. Pndic artery and 
 
 nerve, and 
 nerve to obtu- 
 rator internus. 
 
 3. Great sacro- isch- 
 
 iatic nerve. 
 
 4. Ischiatic artery. 
 
 5. Internal circum- 
 
 flex artery. 
 
 6. The first perfor- 
 
 ating artery. 
 
 THE ARTERIES OF THE GLUTEAL REGION. 
 
 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, 
 and communicates with the short saphenous nerve. 
 
 ISCHIATIC This branch of the internal iliac leaves the 
 
 ARTERY. pelvis between the pyriformis and the gemellus 
 
 superior ; it then descends between the tuber ischii and the great 
 trochanter, along the inner side of the great ischiatic nerve. It 
 gives off: 
 
POPLITEAL REGION. 541 
 
 1, two or more considerable branches to the gluteus maxim us j 2, a 
 coccygeal branch, which runs through the great sacro-ischiatic ligament, 
 then ramifies in the gluteus 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. 522). 
 
 PUDIC AETEBY The course of this artery and nerve has been 
 AND NEEVB. f u iiy described (p. 425). 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 com- 
 press 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.* 
 
 POPLITEAL ^ * 8 advisable to examine the popliteal space 
 
 SPACE. ITS at this stage of the dissection, in order that the 
 
 BOUNDAEIKS. 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, 
 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 space to the back of 
 the leg. 
 
 The muscular fascia covering the space is very strong, and 
 strengthened by numerous transverse fibres. It is pierced by 
 the posterior saphena vein, which passes in to join the popliteal 
 vein. 
 
 The fascia having been reflected, the muscles and tendons con- 
 stituting 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- 
 
 * MJ. 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. 
 
542 POPLITEAL REGION. 
 
 verging heads of the gastrocnemiiis : its shape is therefore that 
 of a lozenge. It extends, above, as high as the lower third of the 
 femur, and, below, as far as the upper sixth of the tibia. Above, it 
 is bounded on the inner side by the semitendinosus, sernimem- 
 branobus, 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 the popliteal 
 vessels and nerves, in the following order : nearest to the surface 
 are the nerves ; the artery lies close to the bone, the vein being 
 superficial to the artery (fig. 125). 
 
 GREAT Along the outer border of the semimembranosus, 
 
 ISCHIATIC NERVE, and covered by the long head of the biceps, is the 
 great ischiatic 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 or external popliteal and the internal popliteal. 
 
 The peroneal nerve runs close by the inner side of the tendon 
 of the biceps,* and subsequently in the groove between this 
 muscle and the outer head of the gastrocnemius, towards the head 
 of the fibula. As it passes round the joint it gives off two arti- 
 cular branches to the knee, which accompany the articular 
 arteries, and a recurrent articular branch, which runs with the 
 recurrent tibial artery to the front of the knee. It supplies also 
 two or three cutaneous branches to the posterior and outer sur- 
 faces of the leg. 
 
 The communicans peronei (fig. 125) is a small branch given 
 off as the nerve passes over the gastrocnemius ; it joins the short 
 saphenous which runs down the back of the calf, and behind the 
 outer ankle, to supply the outer side of the foot and little toe. 
 
 Below the head of the fibula we have already traced the divi 
 
 * The nerve is, therefore, very liable to be injured in the operation of dividing the 
 outer hamstring. In the diagram, the nerve is not near enough to the tendon, their 
 connections having been severed. 
 
POPLITEAL KEG1ON. 
 
 543 
 
 sion of the peroneal into the anterior tibial, and the musculo- 
 cutaneous nerves (p. 532). 
 
 The internal popliteal nerve accompanies the popliteal artery, 
 and, at the lower border of the popliteus, is continued under the 
 name of the posterior tibial. The nerve in the popliteal space lies 
 
 . 125. 
 
 Semitendinosus. 
 
 Semimembranosus. 
 
 Gracili?. 
 
 Sartorius. 
 
 Inner head of gastrocne- 
 mius. 
 
 LEFT POPLITEAL SPACE. 
 
 superficial to and rather external to the artery, and gives off 
 'muscular branches which supply the gastrocnemius, the plantaris, 
 the soleus, and the popliteus ; three articular branches, two accom- 
 panying the articular arteries, the third piercing the back of the 
 capsule ; and the short saphenous, which descends in the groove 
 between the two heads of the gastrocnemius, about the middle of 
 
544 POPLITEAL REGION. 
 
 the leg, is joined by the communicans peronei, and then, running 
 down behind the outer malleolus in company with the short 
 saphena vein, is distributed to the outer side of the little toe. 
 The remainder of the nerve, as posterior tibial, supplies all the 
 flexor muscles on the back of the leg and the sole of the foot. 
 
 POPLITEAL By clearing out all the fat, we observe that the 
 
 VESSELS. popliteal vessels enter the ham through an aperture 
 
 in the adductor magnus, and 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. The popliteal artery lies upon the triangular 
 surface at the back of the lower third of the femur; then, upon the 
 ligamentum posticum Winslowii ; and, lastly, upon the popliteus, at 
 the lower border of which it divides into the anterior and posterior 
 tibial. Arising at right angles from the popliteal artery are the two 
 superior articular arteries ; lower down are two inferior articular 
 arteries ; also the sural, supplying the muscles of the calf, and the 
 azygos artery ; close to the vessel is the articular branch of the 
 obturator nerve which supplies the knee-joint. 
 
 The popliteal vein lies superficial to the artery, and rather to 
 its outer side. It receives the short saphena vein. Its coats are 
 remarkably thick, and on transverse section resemble those of an 
 artery of a similar size. 
 
 LYMPHATIC Two or more lymphatic glands are situated one 
 
 GLANDS. on each side of the artery. They deserve attention, 
 
 because, when enlarged, their close proximity to the artery may com- 
 municate a pulsation which might be mistaken for an aneurysm. 
 
 DISSECTION OF THE BACK OF THE THIGH. 
 
 The incision should be continued along the remainder of the 
 back of the thigh, and the skin reflected. 
 
 CUTANEOUS ^he s ^ m a ^ ^ ne ^ ac ^ ^ * ne thigh is supplied by 
 
 NEBVES AND the lesser ischiatic nerve, which runs down beneath 
 
 VEINS, the fascia, as low as the upper third of the calf, 
 
HAMSTRING MUSCLES. 545 
 
 distributing branches on either side. On the outer side are seen 
 a few cutaneous branches from the posterior division of the ex- 
 ternal cutaneous nerve. 
 
 The subcutaneous veins at the back of the thigh are very small : 
 here they would be liable to pressure. But near the popliteal 
 space there is a vein, called the short saphena. It comes up the 
 back of the calf, and joins the popliteal vein after perforating the 
 strong fascia covering the space. 
 
 MUSCULAR Respecting this, remark that its fibres run 
 
 FASCIA, chiefly in a transverse direction, that it becomes 
 
 stronger as it passes over the popliteal space, and that here it is 
 connected with the tendons on either side. Remove it, to examine 
 the powerful muscles which bend the leg, called the hamstrings. 
 
 HAMSTRING There are three of these, and all arise by strong 
 
 MUSCLES. tendons from the tuber ischii. One, the biceps, is 
 
 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 popliteal, which is occu- 
 pied by soft fat, the popliteal vessels, nerves, and lymphatic 
 glands. 
 
 -o This muscle has two origins, a long and a short. 
 
 The long head arises, by a strong tendon, from 
 the back part of the tuber ischii in common with the semi- 
 tendinosus ; the short head, by fleshy fibres, from the outer lip of 
 the linea aspera of the femur. This origin begins at the linea 
 aspera, just below the insertion of the gluteus maximus, and con- 
 tinues nearly down to the external condyle. It joins the long 
 head of the muscle, and both terminate on a common tendon, 
 which is inserted into the head of the fibula, by two portions 
 separated 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 the muscle which in chronic disease 
 
 N N 
 
546 HAMSTRING MUSCLES. 
 
 of the knee dislocates the leg outwards and backwards, and 
 at the same time rotates it outwards. Each head of the biceps is 
 supplied by the great ischiatic nerve. The short head is some- 
 times supplied by the peroneal. 
 
 SEMITEN- This arises, in common with the biceps, from 
 
 DINOSUS. the back part of the tuber ischii. The fibres ter- 
 
 minate upon a long round tendon, which rests upon the semi- 
 membranosus, and is inserted into the inner surface of the tibia 
 by an expanded tendon, 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. 
 Its nerve comes from the great ischiatic. 
 
 The semitendinosus sends off from the lower border of its ten don 
 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. 
 
 SEMIMEM- This muscle arises from the tuber ischii above 
 
 BRANOSUS. an( j external to the two preceding, by means of a 
 
 strong flat tendon, which extends nearly half-way down the thigh. 
 This tendon descends obliquely under the biceps and semi- 
 tendinosus, and terminates in a bulky muscle, which lies on a 
 deeper plane, and more internal, than the others, and is inserted 
 by a thick tendon into the posterior part of the head of the tibia. 
 In connection with the insertion of this tendon, notice, 1 , that it 
 is prolonged under the internal lateral ligament of the knee, and 
 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 portion of the ligamentum posticum 
 Winslowii, which covers the back of the knee-joint ; 3, that 
 a dense fascia proceeds from its lower border, and binds down the 
 popliteus ; 4, that it is intimately connected with the semilunar 
 cartilages of the joint, so as to keep them in place during its 
 movements. Its nerve comes from the great 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 
 
HAMSTRING MUSCLES. 
 
 547 
 
 FIG. 126. 
 
 half to two inches long. The chief point of interest concerning 
 it is, that it occasionally communicates with the synovial mem- 
 brane of the knee-joint, not directly, but 
 through the medium of another bursa 
 beneath the inner head of the gastro- 
 cnemius. From an examination of 150 
 bodies, it appears that this communication 
 exists about once in five times ; and it 
 need scarcely be said that the proportion 
 is large enough to make us cautious in 
 interfering with this bursa when it be- 
 comes enlarged.* 
 
 ACTION OF THE These muscles produce 
 HAMSTRING two different effects, ac- 
 
 MUSCLES. cording as their fixed 
 
 point is at the pelvis or the knee. With 
 the fixed point at the pelvis, they bend 
 the knee ; with the fixed point at the 
 knee, they take a very important part in 
 maintaining the body erect. For instance, 
 if, when standing, the body be bent at the 
 hip and the muscles in question be felt, it 
 
 will be found that they are in strong action, to prevent 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. 126 ; 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 
 
 * 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 bursae, when enlarged, are apt to become multilocular, and to burrow be- 
 tween the muscles where there is the least resistance. 
 
 v N 2 
 
548 HAMSTEING MUSCLES. 
 
 leg: the bones of the lower extremity represent a pillar which 
 supports the weight of the trunk on a ball-and-socket 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 gluteus 
 medius and minimus ; behind, the hamstrings and gluteus 
 maximus. 
 
 The semimembranosus can also rotate the knee inwards, thus 
 assisting the popliteus. 
 
 The hamstring muscles are supplied with blood by the perfo- 
 rating 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. 
 
 ISCHIATIC This nerve descends from the gluteal region 
 
 NERVE. upon the adductor 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. 542). 
 
 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. 
 
 SHORT OR ^ ne l ar g e ve i n seen m the middle of the back 
 
 POSTERIOR SA- of the leg is called the short or posterior saphena. 
 PHF.NA VEIN. it commences on the outer side of the foot, ascends 
 
 behind the outer ankle, where it has a communication with the 
 deep veins, and then runs up the calf between the two bellies of 
 the gastrocnemius, receiving numerous veins in its course. It 
 eventually passes through the muscular fascia, and joins the 
 popliteal vein. 
 
 The chief cutaneous nerve of the calf is the short or posterior 
 saphenous nerve ; some branches, however, from the long saphenous 
 and lesser ischiatic nerves are to be traced, ramifying in the sub- 
 cutaneous tissue of the inner and upper part of the leg. 
 
MUSCLES OF THE CALF. 549 
 
 SHORT OR ^ ne s ^ or ^ saphenous nerve * is derived from 
 
 POSTERIOR SA- the popliteal (fig. 125), and passes down between 
 PHENOUS NERVE. the two heads of the gastrocnemius to the middle 
 of the calf, where it pierces the fascia. Here it is joined by a 
 branch from the peroneal nerve (communicans peronei) ; it then 
 descends with the short saphena 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. 
 
 MUSCLES OF The great flexor muscle of the foot consists of 
 
 THE CALF. two portions : the superficial one, called the gas- 
 
 trocnemius, 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 os calcis. 
 
 GASTRO- This muscle arises by two strong tendinous 
 
 CNEMIUS. heads, one from the upper and back part of each 
 
 condyle of the femur (fig. 125). The inner head is the larger and 
 longer. The two parts of the muscle descend, distinct from each 
 other, and form the two bellies of the calf, of which the inner is 
 mther the lower. Both terminate, rather below the middle of the 
 leg, on the broad commencement 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 enter the mesial aspect of each head of the muscle. 
 To facilitate the play of the inner tendon over the condyle, there 
 is a bursa, which generally communicates with the knee-joint ; arid 
 in the substance of the outer tendon is commonly found a small 
 
 * This nerve is sometimes called the communicans poplitei, and does not take the 
 name of short saphenous till its junction with the communicans peronei. (P. 542.) 
 
550 MUSCLES OP THE CALF. 
 
 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 and 
 from the posterior ligament of the knee-joint. 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 can be 
 traced down the inner border of the tendo Achillis to the calca- 
 neum. Its nerve comes from the internal popliteal. 
 
 This muscle arises from the head and upper 
 SOLEUS, 
 
 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 aponeurotic 
 arch thrown over the posterior tibial vessels. The muscular fibres 
 bulge out beyond the gastrocnemius, and terminate on a broad 
 tendon, which, gradually contracting, forms a constituent part of the 
 tendo Achillis. The muscle lies upon the flexor longus digitorum, 
 the tibialis posticus, the flexor longus pollicis, and the posterior 
 tibial vessels and nerve. 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 internal 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 can reach the posterior tibial artery ; 2, by reflecting 
 its fibular origin we can 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 
 conveniently and safely divided for the relief of club-foot. There 
 
 * 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, it 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 
 describe as the two heads of the muscle. Between them descend the popliteal vessels, 
 protected by a tendinous arch. 
 
POPLITEAL VESSELS. 
 
 FIG. 127. 
 
 is no risk of injuring the deeper-seated parts, because they are 
 separated from the tendon by a quantity of fat. Its insertion 
 is into the under and back part of the tuberosity 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 Aveight 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 pointing the toes, acts upon a lever of 
 the first order. The fulcrum is at 
 the ankle-joint, F (fig. 127); the re- 
 sistance, w, at the toes ; the power at 
 the heel, F. 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 fulcrum. In raising the body on 
 tiptoe, the tendo Achillis acts on a 
 lever of the second order ; the fulcrum 
 being then at the ball of the great toe, and the weight of the body 
 at the ankle. 
 
 After passing through the opening in the tendon 
 of the adductor magnus, the femoral artery takes 
 the name of popliteal. It descends nearly per- 
 pendicularly 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 
 
 COUBSE AND 
 REI^TIOXS OF THE 
 POPLITEAL 
 AETEBY. 
 
552 POPLITEAL VESSELS. 
 
 lies upon the posterior ligament of the knee-joint, and, lastly, 
 upon the popliteus. At its lower part the artery is covered by the 
 gastrocnemius 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 
 internal popliteal nerve runs also in a similar direction with the 
 vein, but is still more superficial and to the outer side (fig. 125). 
 The vessels and the nerve are surrounded by fat, and one or two 
 lymphatic glands are generally found in the immediate neighbour- 
 hood of the artery, just 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 external and internal 
 run, one above each condyle, close to the bone ; the two inferior exter- 
 nal and internal run below the joint. 
 
 1. The superior external articular artery runs above the external 
 condyle, passes beneath the biceps, and through the intermuscular 
 septum : it then divides into a siiperficial and a deep branch the super- 
 ficial supplies the vastxis externus, and then forms part of the patellar 
 arterial plexus ; the deep branch keeps close to the femur and supplies 
 the joint. 
 
 2. The superior internal articular artery runs above the internal 
 condyle, under the tendon of the adductor magnus and vastus internus, 
 and divides into two branches, a superficial and a deep, which take a 
 corresponding course to those on the outer side. 
 
 3. The inferior external articular artery runs under the gastrocne- 
 mius, over the popliteus, then, passing beneath the external lateral 
 ligament and the tendon of the biceps, it reaches the patella, where it 
 breaks up into branches anastomosing with the other articular arteries. 
 
 4. The inferior internal articular artery runs between the tuberosity 
 of the tibia and the internal lateral ligament, and supplies the inner and 
 anterior part of the joint. 
 
 5. The azygos artery is given off from the deep aspect of the 
 popliteal, pierces the ligamentum posticum Winslowii, to supply the 
 crucial ligaments and the synovial membrane. 
 
 The several articular arteries form over the front and sides of tbe joint 
 a network of vessels which anastomose, superiorly, with the descending 
 
POPLITEAL VESSELS. 553 
 
 branch of the external circumflex and the anastomotica magna ; inferiorly, 
 with the anterior tibial recurrent ; and also among themselves. It is 
 mainly through these channels that the collateral circulation is established 
 in the leg after ligature of the superficial femoral. 
 
 The sural arteries proceed one to each head of the gastrocnemius, 
 and are proportionate in size to the muscle ; one or two branches are 
 distributed to the soleus. These arteries are accompanied by branches 
 of the internal popliteal nerve for the supply of the muscle. 
 
 Small superior muscular branches supply the vasti and hamstring 
 muscles, and inosculate with the perforating and articular arteries. 
 
 POPLITEAL This vein is formed by the junction of the 
 
 VEIN. vense comites of the anterior and posterior tibial 
 
 arteries, and is situated superficial to the artery. It crosses ob- 
 liquely from the inner to the outer side of the artery, and is con- 
 tinued upwards as the femoral. It receives in the popliteal space 
 the short saphena, the articular, and sural veins. 
 
 The insertion of the tendon of the semimembranosus into the 
 head of the tibia, and its several connections, described (p. 546), 
 should now be fully examined. 
 
 p This muscle arises within the capsule of the 
 
 knee-joint, from a depression on the outside of the 
 external condyle by a thick tendon, which runs beneath the ex- 
 ternal lateral ligament. The muscular fibres gradually spread out, 
 and are inserted into the triangular surface of the tibia above the 
 soleal ridge on the bone. It 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. The tendinous origin is in contact with the external semi- 
 lunar cartilage. 
 
 Keflect the soleus from 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, increases in strength towards the ankle, and 
 
554 DEEP MUSCLES AT THE BACK OF THE LEG. 
 
 forms a posterior annular ligament which confines the ' tendons 
 and the vessels and nerves in their passage into the sole of the foot. 
 
 DEEP MUSCLES There are three : the flexor longtis digitorum 
 ON THE BACK OF on the tibial side ; the flexor longus pollicis on 
 THE LEG. y^ fibula^ ; the tibialis posticus upon the inter- 
 
 osseous membrane, between and beneath them both. 
 
 FlJ5XOR This arises from the posterior surface of the 
 
 LONGUS DIGI- tibia, commencing below the popliteus, and ex- 
 
 TORTTM. tending to within four inches of the lower end of 
 
 the bone, also from the fascia over the tibialis posticus. The fibres 
 terminate on a tendon which runs through a groove behind the 
 inner ankle, and, entering the sole, divides into four tendons, which 
 are inserted into the ungual phalanges of the four outer toes. It 
 is supplied by the posterior tibial nerve. 
 
 FLEXOB This powerful muscle arises from the lower two- 
 
 LONGUS POLLICIS. thirds of the posterior surface of the fibula, from 
 the septum between it and the peronei, and from the aponeurosis 
 over the tibialis posticus. The fibres terminate on a tendon which 
 runs through a groove on the back of the astragalus ; thence it 
 passes under the sustentaculum tali, and is inserted into the 
 ungual phalanx of the great toe. The chief 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. 
 
 TIBIALIS This is so concealed between the two preceding 
 
 POSTICUS. muscles that it cannot be properly examined with- 
 
 out reflecting them. It arises from the interosseous membrane, 
 from the opposite surfaces of the tibia and fibula for about their 
 middle three-fifths, and from the aponeurosis covering it. 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, and by fibrous prolongations into 
 most of the tarsal and metatarsal bones. Its action is to bend 
 
POSTERIOR TIBIAL ARTERY. 555 
 
 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 the 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^ inches above the end of the internal malleolus, and is 
 consequently opened in the operation. 
 
 Attention should now be directed to the internal or posterior 
 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 ^elative 
 positions 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 ac- 
 companied by its venae comites ; the posterior tibial nerve ; and, 
 lastly, the tendon of the flexor longus pollicis. 
 
 COUBSE AND This artery is one of the branches into which 
 
 KELATIONS OF the popliteal divides at the lower border of the 
 THE POSTEBIOB popHtcus. It descends over the deep muscles at 
 TIBIAI. ABTEBT. thg back of the le g ^ ^ interval between the 
 
 internal malleolus and the os calcis, and, entering the sole, divides 
 beneath 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 compressed. 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 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 f of an inch 
 
556 POSTERIOR TIBIAL ARTERY. 
 
 distant. Here, being comparatively superficial, it may easily be 
 tied. Immediately bebind the internal malleolus, it lies between 
 tbe 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. The posterior tibial nerve which 
 accompanies the artery is at first on its inner side, then crosses 
 over it, and for the greater part of its course lies external to the 
 artery. Its branches are as follows : 
 
 a. Numerous muscular branches to the soleus and the deep muscles. 
 
 b. The peroneal is a branch of considerable size ; often as large as 
 the posterior tibial. Arising about an inch below the division 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 embedded among the muscles : being covered, first, 
 by tbe soleus, afterwards by the flexor longus pollicis. To both these 
 muscles, to tbe latter especially, 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 tbe under aspect of tbe 
 peroneus tertius, then runs in front of the tibio-fibular articulation, 
 and inosculates with the other malleolar and tarsal arteries. The 
 peroneal supplies tbe nutrient artery of the fibula, and, about an inch 
 above the os calcis, sends off a transverse communicating branch, which 
 inosculates with the posterior tibial artery under the tendon of the flexor 
 longus pollicis. 
 
 c. The nutrient artery of the tibia. 
 
 POSTERIOR This is the continuation of the popliteal. It 
 
 TIBIAL NERVE. descends close to its corresponding artery, and, 
 behind the inner ankle, divides into the external and internal 
 plantar nerves. In the first part of its course the nerve lies super- 
 ficial to the artery, and rather to its inner side ; but lower down 
 the nerve crosses the artery, and passes to its outer side. It sup- 
 plies branches to the three deep-seated muscles, and a cutaneous 
 branch calcaneo-plantar to the sole of the foot, 
 
557 
 
 DISSECTION OF THE SOLE OF THE FOOT. 
 
 Make a perpendicular incision down the middle 
 .DISSECTION 
 
 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 toes ; 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 toes, we often meet with bursae, simple or multilocular. 
 They are generally placed between the skin and the sesamoid bones, 
 and have remarkably thick walls. Frequently an artery an\i nerve 
 can be traced running directly through one of these sacs, wi ich 
 explains the acute pain produced by their inflammation. 
 
 CUTANEOUS The skin of the heel is supplied by the calcaneo- 
 
 NERVES. plantar 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. 
 
 PIANTAR This is a remarkably dense white and glistening 
 
 FASCIA. fascia. It extends from the under and back part 
 
 of the os calcis to the distal extremities of the metatarsal bones. 
 It is divided into a strong central and two lateral less dense por- 
 tions ; from which prolongations pass deeply inwards, separating 
 the lateral from the central muscles. The middle portion, cover- 
 ing the flexor brevis digitorum, is narrow behind, and, as it passes 
 forwards towards the toes, is spread out, and strengthened by trans- 
 verse fibrous bands. The inner portion is comparatively thin, and 
 surrounds the abductor pollicis, becoming continuous posteriorly 
 with the internal annular ligament. The outer portion is thicker 
 than the inner, especially as it passes forwards to be attached to 
 the proximal end of the fifth metatarsal bone. It covers the 
 abductor minimi digiti. 
 
 Near the distal ends of the metatarsal bones, the central part 
 
558 SOLE OF THE FOOT. 
 
 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 between the 
 toes are seen the digital vessels and nerves. This arrangement is 
 in all respects like that in the palm. 
 
 In the interdigital folds of the skin, there are also ligamentous 
 fibres, which run from one side of the foot to the other, and answer 
 the same purpose as those in the hand (p. 298). 
 
 The plantar fascia must be partially removed to examine the 
 muscles. Towards the os calcis its removal is not accomplished 
 without some difficulty, since the muscles arise from it. 
 
 SUPERFICIAL After the removal of the fascia three muscles 
 
 MUSCLES. a re exposed. All 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 abductor pollicis, 
 and the abductor minimi digiti. 
 
 ABDUCTOB This muscle arises from the inner and back part 
 
 POLLICIS. of the os calcis, from the plantar fascia, and from 
 
 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. 
 
 ABDUCTOB This muscle has a very strong origin from the 
 
 MINIMI DIGITI. under surface of the os calcis, from its external 
 tubercle, from the plantar fascia, and from the external inter- 
 muscular septum. 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. 
 
 * They are separated from each other by strong perpendicular partitions inter- 
 muscular septa which pass in from the plantar fascia. 
 
SOLE OF THE FOOT. 
 
 559 
 
 FLEXOR EHEVIS This muscle arises from the under surface of 
 DIGITORUM. the os calcis, 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 through ; then the two 
 slips, reuniting, are inserted into the sides of the second phalanx. 
 
 FIG. 128. 
 
 1. Abductor mi- 
 
 nimi digiti. 
 
 2. Flexor accesso- 
 
 rius. 
 
 3. Abductor pollicis 
 
 4. External plantar 
 
 artery aud 
 nerve. 
 
 5. Tendon of flexor 
 
 longus pollicis. 
 
 6. Internal plantar 
 
 artery and 
 nerve. 
 
 7. Flexor longus 
 
 digitorum. 
 
 8. Flexot- brevis 
 
 minirm tl'giti. 
 
 9. Lumbricald . 
 
 10.' Internal r7.an- 
 tar nerve. 
 
 11. Tendons of the 
 flexor brevis 
 digitorum bi- 
 furcating, for 
 the passage of 
 the tendons of 
 the flexor lon- 
 gus digitorum. 
 
 MUSCLES, VESSELS, AND NERVES OF THE SOLE OF THE RIGHT FOOT, AFTER 
 REFLECTION OF THE FLEXOR BREVIS DIGITORUM. 
 
 The same arrangement prevails in the fingers. It is supplied by 
 the internal plantar nerve. 
 
 The three superficial muscles should now be reflected, by saw- 
 ing off about half an inch of the os calcis, and then turning it 
 downwards with the 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. 
 
560 SOLE OF THE FOOT. 
 
 TENDON OF THE Tracing this tendon into the sole, you find that 
 
 FLEXOR Loxous an accessory muscle is attached to it. The flexor 
 
 DIGITORUM. accessorius arises by muscular fibres from the 
 
 MUSCULUS Ac- inner gide of the og ca i cis and k y tendinous fibres 
 
 CESSORIUS. ' 
 
 from the outer side in front of the external tuber- 
 cle. Its fibres run straight forwards, and are inserted into the 
 fibular side of the upper surface 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 their divisions, are inserted into the bases 
 of the ungual phalanges. Eespecting the manner in which the ten- 
 dons are confined by fibrous sheaths, and lubricated by a synovial lin- 
 ing, what was said of the fingers (p. 304) applies equally to the toes. 
 The flexor accessorius is supplied by the external plantar nerve. 
 
 These four little muscles are placed between 
 
 the long 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 first 
 phalanges of the toes. Concerning their use, refer to p. 306. The 
 two outer lumbricales are supplied by the external plantar nerve, 
 the two inner by the internal. 
 
 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 caicis, above, that is nearer to the bones than 
 the tendon of the flexor longus digitorum, and then straight to 
 the base of the last phalanx. It crosses the long flexor tendon of 
 the toes, and the two tendons are connected by an oblique slip ; 
 so that we cannot bend the other toes without the great toe. 
 
 PLANTAR The posterior tibial artery, having entered the 
 
 ARTERIES. sole between the origins of the abductor pollicis, 
 
 divides into the external and internal plantar arteries. 
 
SOLE OF THE FOOT. 
 
 561 
 
 FIG. 129. 
 
 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, and then is continued along the inner 
 side of that toe, where it terminates in small inosculations 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 (fig. 129). It 
 runs obliquely outwards across the sole to- 
 wards the base of the fifth metatarsal bone ; 
 then, sinking deeply, it bends inwards across 
 the bases of the metatarsal bones, and inos- 
 culates with the dorsalis pedis in the first 
 interosseous space. At first it lies between 
 the os calcis and the abductor pollicis ; it 
 then passes between the flexor brevis digi- 
 torum and the flexor accessorius ; and, lastly, 
 it lies deep beneath the flexor tendons, and 
 the adductor pollicis, close to the metatarsal 
 bones. Deeply seated as it appears to be, that 
 part of its curve near the fifth metatarsal 
 bone lies immediately beneath the fascia. 
 
 The external plantar sends a branch to 
 the skin of the heel, and another round the 
 outer edge of the foot ; but its chief branches 
 are the four digital arteries, which arise 
 in the deepest 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 second, being supplied by the dorsalis hallucis. Concerning 
 the ultimate distribution of the digital arteries, refer to the ac- 
 count given of these arteries in the hand (p. 300). 
 
 Besides the digital arteries, the arch gives off three small 
 branches the perforating which ascend between the three outer 
 interosseous spaces, and inosculate with the dorsal interosseous 
 arteries at each end of the spaces. 
 
 O 
 
 1. Internal plantar artery. 
 
 2. External do. 
 
562 SOLE OF THE FOOT. 
 
 PLANTAR The posterior tibial nerve divides, like the 
 
 NERVES, artery, into an external and internal plantar. The 
 
 internal plantar is the larger, and supplies nerves to the three 
 inner 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, 
 and 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 accompanies the plantar arch, and fur- 
 nishes nerves to the two outer lumbricales, the adductor pollicis, 
 the transversalis pedis, and all the interossei. 
 
 THIRD LAYEE Having traced the principal vessels and nerves, 
 
 OF MUSCLES. divide 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 transver- 
 salis pedis. 
 
 FLEXOB BREVIS This muscle arises by a flat tendon from the 
 POLLICIS. cuboid bone, and from the fibrous prolongation of 
 
 the tibialis posticus into the external cuneiform. 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 walk- 
 ing the tendon is not pressed upon. Its nerve comes from the 
 internal plantar. 
 
 ADDUCTOR This very powerful muscle arises from the 
 
 POLLICIS. bases of the third and fourth metatarsal bones, 
 
SOLE OF THE FOOT. 563 
 
 and from the sheath of the peroneus longus. Passing obliquely 
 forwards and inwards 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. 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. Its nerve is derived from 
 the external plantar. 
 
 FLEXOR BREVIS This little muscle arises from the base of the 
 MINIMI Diem. " fifth metatarsal bone and the sheath of the pero- 
 neus longus, proceeds forward along the bone, and is inserted into 
 the base of the first phalanx of the little toe. It is supplied by 
 the external plantar nerve. 
 
 TRANSVEBSAUS This slender muscle runs transversely across 
 PEDIS. the distal ends of the metatarsal bones. It arises 
 
 by little fleshy slips -from the bases of 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. Its nerve 
 comes from the external plantar. 
 
 The fourth layer of muscles consists of the interossei. 
 
 These muscles are arranged nearly like those in 
 the hand. They occupy the intervals between the 
 metatarsal bones, and are seven in number, four being on the 
 dorsal aspect of the foot, three on the plantar. The four dorsal 
 interossei arise each by two heads from the contiguous sides of 
 the metatarsal bones, and are inserted into the bases of the first 
 phalanges. The first is inserted into the inner side of the second 
 toe ; the remaining three into the outer sides of the second, third, 
 and fourth. The plantar interossei, three in number, arise from 
 the inner sides and under surfaces of the third, fourth, and fifth 
 metatarsal bones, and are inserted respectively into the inner 
 sides of the bases of the first phalanges of the third, fourth, and 
 fifth toes. 
 
 The use of the interosseous muscles is to draw the toes to or 
 from each other, and they do the one or the other according to the 
 side of the phalanx on which they act. Now, if we draw a lorgi- 
 
 o o 2 
 
564 LIGAMENTS OF THE PELVIS. 
 
 tudinal 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 
 of these muscles is given in the dissection of the hand (p. 336). 
 Between the tendons of the interossei, that is, between the distal 
 ends of the metatarsal bones, there are bursae which facilitate 
 movement. They sometimes become enlarged and occasion painful 
 swellings between the roots of the toes. The flexor brevis minimi 
 digiti, the tran-sversalis pedis, and all the interossei are supplied 
 by the external plantar nerve. 
 
 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. Prolongations are sent off to the cuneiform bones, to 
 the cuboid, to the sustentaculum tali, and to the bases of the 
 second, third, and fourth metatarsal 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. 
 
 DISSECTION OF THE LIGAMENTS. 
 
 LIGAMENTS OF The sacrum is united to the last lumbar ver- 
 
 THEPBLTIS. tebra in the 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. 246). 
 
 The innominate bones are connected to each other in front, 
 constituting the symphysis pubis ; posteriorly to the sacrum, con- 
 stituting the sacro-iliac symphysis. 
 
LIGAMENTS OP THE PELVIS. 
 
 565 
 
 PDBIC STM- This is secured by, 1, an anterior ligament, 
 
 PHYSIS. consisting of irregular superficial fibres which run 
 
 obliquely, and of deep fibres which pass transversely ; 2 r a pos- 
 terior ligament, less distinct ; 3, a sub-pubic ligament : 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 
 that its general structure resembles that between the bodies of the 
 vertebrae. In the upper and back part of this fibro-cartilage is a 
 
 FIG. 130. 
 
 Great sacro-ischiatic ligament 
 Lesser sacro-ischiatic ligiment 
 
 Ilio-femoral or accessory liga- 
 ment of the hip-joint. 
 
 smooth cavity lined with epithelium. The cartilage acts like a 
 buffer, and breaks the force of shocks passing through the pelvic 
 arch. 
 
 The ilium 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 
 ilium (fig. 131). 
 
 SACRO-ILIAC This is secured by, 1, an anterior ligament 
 
 SYMPHYSIS. w hi c h consists of ligamentous fibres passing in 
 
 front ; 2, a posterior ligament, composed of fibres much stronger 
 
566 LIGAMENTS OF THE HIP-JOINT. 
 
 and more marked, which pass behind the articulation. A well- 
 marked fasciculus of fibres passes from the posterior superior spine 
 to the third segment of the sacrum, and is called the oblique sacro- 
 iliac ligament. 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. 
 
 SACEO-ISCHIATIC These are two strong ligaments passing from 
 LIGAMENTS. the sacrum to the ischium. The great sacro- 
 
 ischiatic is triangular, and extends from the posterior inferior 
 spine of the ilium, 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, 
 where it narrows considerably. It lies anterior to the preceding 
 ligament. These two ligaments not only connect the bones, but 
 also, from their great breadth, contribute to diminish the lower 
 aperture of the pelvis. 
 
 LIGAMENTS OF This joint is secured by the form of the bones, 
 
 THE HIP-JOINT. and by the strength of the powerful muscles which 
 surround it. Although 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. 
 
 CAPSULAR The capsular ligament is attached above to 
 
 LIGAMENT. the circumference of the acetabulum, a little 
 
 external to the margin, and also to the transverse ligament ; 
 below, to the inter-trochanteric ridge of the femur in front, and to 
 the middle of the neck behind. The capsule is rendered exceed- 
 ingly thick and strong in front by a broad ligament, ilio-femoral, 
 which extends from the anterior inferior iliac spine, and then 
 divides like the two arms of the inverted. letter jr^, one, the inner, 
 passes to the lesser trochanter, the outer, to the upper part of the 
 anterior inter-trochanteric ridge. This ligament is very strong, 
 
LIGAMENTS OF THE HIP-JOINT. 
 
 567 
 
 serves as a strap to prevent the femur being extended beyond a 
 certain point, and limits rotation inwards and outwards. 
 Open the capsule to as- F IO _ 
 
 certain its great thickness in 
 front, and its strong attach- 
 ment to the bones. This 
 exposes the cotyloid liga- 
 ment, and the ligamentum 
 teres. 
 
 LlGAMENTUX Tll6 Hga- 
 
 TEHES. mentum teres 
 
 is exposed by drawing the head 
 of the femur out of the socket. 
 This ligament is somewhat 
 flat and triangular. Its base, / 
 which is bifid, is attached, be- \ 
 low, to the borders of the notch 
 in the acetabulum ; its apex, 
 to the fossa in the head of 
 the femur. To prevent pres- 
 sure 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 ligamentum teres is surrounded by the synovial mem- 
 brane. An 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. 131): it therefore prevents 
 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. 
 
 VERTICAL SECTION THROUGH THE HIP. 
 
568 LIGAMENTS OP THE KNEE-JOINT. 
 
 COTYLOID The cotyloid ligament is a piece of fibro-cartilage 
 
 LIGAMENT. - which is attached all round the margin of the ace- 
 
 tabulum. 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 transverse ligament. 
 
 The ligaments of the hip are so arranged that, when we stand 
 ' at ease,' the pelvis is spontaneously thrown into a position in which 
 its range of motion is the most restricted ; for the accessory liga- 
 ment (ilio-femoral) of the capsule prevents it from rolling back- 
 wards, 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 atmospheric pressure 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 bones 
 are no longer maintained in accurate contact ; and it sometimes 
 happens that the head of the femur escapes from its cavity, giving 
 rise to a spontaneous dislocation. 
 
 LIGAMENTS OF The knee is a hinge-joint, and, looking at the 
 
 THE KNEE-JOINT. skeleton, one would suppose that it was very 
 insecure. But this insecurity is only apparent ; the joint being 
 surrounded by powerful ligaments, and a thick capsule formed by 
 the tendons of the muscles which act upon it. 
 
 First examine the tendons concerned in the protection of 
 the knee-joint. In front is the ligamentum patellae; on either 
 side are the tendons of the vasti ; at the back of the joint are four 
 tendons 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 joint is near the tendon of the 
 popliteus : here, therefore, pus formed in the popliteal space may 
 make its way into the joint, or vice versa. 
 
LIGAMENTS OF THE KNEE-JOINT. 
 
 569 
 
 The proper ligaments of the joint are 1, the lateral', 2, the 
 crucial in the interior. 
 
 INTERNAL This is a broad flat band, which extends from 
 
 LATERAL LIGA- the inner condyle of the femur to the inner side 
 MENT - of the tibia, a little below its head (fig. 132). A 
 
 few of the deeper fibres are attached to the inner semi-lunar carti- 
 lage, and serve to keep it in place. The inferior internal articular 
 artery, and part of the tendon of the semimembranosus, pass under- 
 neath this ligament. In the several motions of the joint, there 
 F IG . 132. is a certain amount of friction between 
 
 the ligament and the head of the tibia, 
 and consequently a small bursa is in- 
 terposed. 
 
 EXTERNAL LA- This IS a strong 
 
 TERAL LIGAMENT. round band, which ex- 
 tends 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 shwt 
 external lateral ligament. 
 
 POSTERIOR This, which is gene- 
 
 LIGAMENT. rally called ' ligamen- 
 
 tumposticum WinslowiiJ consists of 
 expansions derived from the tendons at 
 the back of the joint, chiefly, however, 
 from the semimembranosus (p. 546). 
 It extends from the posterior part of the tuberosity of the tibia to 
 the outer condyle of the femur. 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.* It allows the free play of the bone over the lower part 
 
 * In performing operations near the knee, the joint should always be bent, in 
 order to draw the synovial fold as much as possible out of the way. 
 
 DIAGRAM OF THE SEMI-LUNAR 
 CARTILAGES AND LATERAL LI- 
 GAMENTS OF THE KNEE. 
 
 1. Internal lateral ligament. 
 
 2. External ditto. 
 
570 LIGAMENTS OF THE KNEE-JOINT. 
 
 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 sy no vial 
 
 SYNOVIAL MEM- membrane proceeds backwards to the space between 
 BRANE. the condyles, and is called the ligamentum mu- 
 
 cosum. Two similar horizontal folds are termed 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. 
 
 Outside the synovial membrane there is always fat ; especially 
 under the ligamentum patellae. Its use is to fill up vacuities, and 
 to mould itself to the several movements of the joint. 
 
 CRUCIAL The crucial ligaments, so named because they 
 
 LIGAMENTS. cross like the letter X, extend from the mesial 
 
 side of each condyle to the head of the tibia. The anterior or 
 external, the smaller, ascends from the inner part of the fossa in 
 front of the spine of the tibia, backwards and outwards to the 
 inner and back part of the external condyle. The posterior or 
 internal, best seen from behind, extends from the back of the 
 fossa behind the spine of the tibia forwards to the front of the 
 inner condyle. 
 
 Between the condvles and the articular surfaces 
 
 INTER-ARTI- < J 
 
 CULAR OR of the tibia are two incomplete rings of fibro- 
 
 SEMI-LUNAR cartilage, shaped like the letter C. They serve 
 
 CARTILAGES. ^ d ee p en the articular surfaces of the tibia ; their 
 
 mobility and flexibility enable them to adapt themselves to the 
 condyles in the several movements of the joint ; they distribute 
 pressure over a greater surface and break 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. 132. Their form is suited to 
 the condyles, the inner being oval, the outer circular, and the 
 synovial membrane covers both surfaces of the cartilages. 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 external one 
 
LIGAMENTS OP THE KNEE-JOINT. 571 
 
 lie within those of the internal which are attached further from the 
 spine. The cartilages are connected in front by a thin transverse 
 ligament ; and their circumference is attached round the head of 
 the tibia by fibrous tissue, called the coronary ligament (seen in 
 fig. 132), yet not so closely as to restrict their range of motion.* 
 
 ACTION OF THE Their respective points of attachment are such 
 LIGAMENTS. that, when the joint is 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 on its own 
 axis, but by rotation of the outer head round the inner. FlG> 133- 
 Rotation 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 eoronoid process and 
 the olecranon of the elbow. They make the tibia slide 
 properly forwards and backwards. In extension, the 
 anterior crucial ligament is tight ; in flexion, the posterior 
 ligament becomes tight and consequently limits flexion. CRUCIAL 
 They also conjointly limit excessive rotation. They not LIGAMENTS 
 only prevent dislocation in front or behind, but they OFTHB 
 prevent lateral displacement, since they cross each other 
 like braces, as shown in fig. 133. 
 
 SUPERIOR There is a joint between the tibia and fibula at 
 
 TIBIO-FIBULAR their upper and lower extremities. The upper 
 JOINT> joint is secured by an anterior and a posterior 
 
 tibio-fibular ligament; their fibres are very strong and run in 
 an oblique direction downwards and outwards, passing from the 
 external tuberosity of the tibia to the head of the fibula. The 
 
 * 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 external lateral ligament ; so far from 
 this, it is separated from it by the tendon of the popliteus, of which the play is facili- 
 tated by a bursa communicating freely with the joint. For this reason the external 
 cartilage is more liable to dislocation than the internal. 
 
572 LIGAMENTS OF THE ANKLE-JOINT. 
 
 contiguous surfaces of the bones are crusted with cartilage. In the 
 large majority of instances the synovial membrane is a separate 
 one, but it occasionally communicates with the synovial membrane 
 of the knee-joint. 
 
 INTEROSSEOUS The contiguous borders of the tibia and fibula 
 
 MEMBRANE. are connected by the interosseous membrane. The 
 
 purpose of it is to afford additional surface for the attachment 
 of muscles. Its fibres pass chiefly downwards and outwards from 
 the tibia to the fibula, but a few fibres cross like the letter X. 
 The anterior tibial artery comes forwards above the interosseous 
 membrane, through an oval space about an inch below the head 
 of the fibula. Lower down there is an aperture for the anterior 
 peroneal artery. It is moreover pierced here and there by small 
 blood-vessels. 
 
 INFERIOR The lower extremities of the tibia and fibula 
 
 TIBIOFIBVLAR are firmly connected, for it is essential to the 
 security of the ankle-joint that there should be 
 little or no movement between the two bones. The anterior 
 ligament is composed of oblique fibres which pass downwards from 
 the tibia to the fibula; the posterior ligament is stronger and 
 narrower than the anterior, and its fibres pass horizontally from 
 the outer malleolus to the posterior border of the tibia, above 
 the articular surface. The inferior interosseous ligament connects 
 the contiguous surfaces of the two bones. The synovial membrane 
 of this joint is an extension upwards of that of the ankle- 
 joint. 
 
 LIGAMENTS OF From the form of the bones, it is obvious 
 
 THE ANKLE-JOINT. ha,t the ankle is a hinge-joint ; consequently, 
 its security depends upon the great strength of its lateral liga- 
 ments. The hinge, however, is not so perfect but that it ad- 
 mits 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. 
 
 INTERNAL This ligament, sometimes called, from its shape, 
 
 LATERAL deltoid, is exceedingly thick and strong, and 
 
 LIGAMENT. compensates for the comparative shortness of the 
 
LIGAMENTS OP THE ANKLE-JOINT. 573 
 
 malleolus on this side (fig. 134). The great strength of it is proved 
 by the fact that, in dislocations of the ankle inwards, the summit 
 of the malleolus is more often broken off than the ligament 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, to the scaphoid bone, and to the 
 inferior calcaneo-scaphoid ligament, which it firmly braces up 
 (fig. 134). 
 
 EXTERNAL This ligament consists of three distinct fasciculi 
 
 LATERAL an anterior, a posterior, and a middle (fig. 1 35). 
 
 LIGAMENT. ^11 three arise from surfaces near the summit of 
 
 FIG. 134. 
 
 1. Plantar fascia. 
 
 2. Calcaneo-scaphoid ligament which supports the head of the astragalus. 
 
 3. Internal lateral ligament, called from its shape deltoid. 
 
 the external malleolus ; the first two are inserted into the front and 
 the back of the astragalus respectively ; the middle into the outer 
 surface of the os calcis. 
 
 ANTERIOR AND The closure of the joint is completed, in front 
 POSTERIOR and behind, by an anterior and a posterior liga- 
 
 LIGAMENTS. ment attached to the bones near their articular 
 
 surfaces, and sufficiently loose to permit the necessary range of 
 motion. 
 
 Besides flexion and extension, the ankle-joint admits of a 
 
574 
 
 LIGAMENTS OF THE TAKSAL JOINTS. 
 
 slight lateral movement, only permitted in the extended state, 
 FIG. 135. for the better direction of our steps. 
 
 In adaptation to this movement the 
 internal malleolus is 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 object 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. 
 
 LIGAMENTS The astragalus is the 
 
 CONNECTING THE key-stone of the arch of 
 BONES OF THE the foot, and supports 
 FooT - the whole weight of the 
 
 body. It articulates with the os calcis 
 and the os scaphoides in such a manner as to permit the abduction 
 and adduction of the foot, so useful in the direction of our steps. 
 
 ASTRAGALO- The astragalus articulates with the os calcis, by 
 
 CALCANEAL LiGA- two distinct surfaces separated by the interosseous 
 MENTS - groove, of which the anterior is convex, the 
 
 posterior slightly concave. The interosseous ligament descends 
 vertically in the interosseous canal, and is the principal bond 
 of union between the two bones. The posterior ligament is a 
 short oblique band, which passes from the posterior border of the 
 astragalus to the upper border of the os calcis. The external 
 ligament passes vertically from the astragalus to the os calcis. 
 
 ASTEAGALO- The anterior surface of the astragalus is broadly 
 
 SCAPHOID LIQA- convex, fitting into the concave surface of the 
 MENT> scaphoid. Superiorly, the surfaces of the two 
 
 bones are connected by a broad ligament, astragalo-scaphoid, 
 which blends with the external calcaneo-scaphoid. 
 
 DIAGRAM OF THE EXTERNAL 
 LATERAL LIGAMENT. 
 
 1. Anterior part. 
 
 2. Posterior part. 
 
 3. Middle part. 
 
 4. Interosseous ligament between 
 
 the astragalus and os calcis. 
 
LIGAMENTS OP THE TARSAL JOINTS. 
 
 575 
 
 CALCANEO- 
 SCAPHOID LIGA- 
 MENT. 
 
 FIG. 136. 
 
 In the skeleton the head of the astragalus 
 articulates in front with the scaphoid, but the 
 lower part of it is unsupported. This interval is 
 bridged over by a very strong and slightly elastic ligament, which 
 extends from the os calcis to the scaphoid (fig. 1 34). These bones, 
 together with the 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 ligament being slightly 
 elastic, allows the keystone of the arch (the astragalus) a play, 
 which is of great service in preventing concussion of the body. 
 Whenever this ligament yields, the head of the astragalus falls, 
 and the individual becomes gradually flat-footed. 
 
 The ligament is thick and strong, and passes horizontally for- 
 wards from the sustentaculum tali to the plantar surface of the 
 scaphoid, where it is connected with the tendon 
 of the tibialis posticus, and, superiorly, with 
 the astragalo-scaphoid ligament. The external 
 calcaneo-scaphoid ligament is short, lying in 
 the hollow between the astragalus and os calcis, 
 and passes from the ridge on the anterior part of 
 the os calcis to the outer side of the scaphoid. 
 CALCANEO- The os calcis articulates with 
 
 CUBOID JOINT. the os cuboides nearly on a 
 
 line with the joint between the astragalus and 
 the scaphoid. The bones are firmly connected 
 by the inferior calcaneo- cuboid ligament, of 
 which the superficial portion, the ligamentum 
 longum plantce, is attached to the os calcis as 
 far as the tubercle, and passes forwards to the 
 plantar aspect of the cuboid ; some of its fibres 
 extend to the second, third, and fourth meta- 
 tarsal bones, and complete the canal for the 
 tendon of the peroneus longus. The ligamen- 
 tum breve plantce is very broad, and passes 
 from the os calcis to the inner side of the cuboid bone. 
 
 The dorsal ligament connects the upper surfaces of the bones. 
 
 1. Calcaneo-scaphoid 
 
 ligament. 
 
 2. Calcaneo-cuboid 
 
 ligament. 
 
576 
 
 TARSO-METATAKSAL JOINTS. 
 
 The remaining bones of the tarsus are connected and main- 
 tained in position by dorsal and plantar ligaments, and strong 
 interosseous bands which pass between their contiguous surfaces. 
 137. 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 
 ous ligament distributed, and consequently there is a firmer 
 the wedge bones. ^ as j s f or the SU pp 0r t of the body. Being com- 
 posed, moreover, of several pieces, each of which possesses a certain 
 
 FIG. 138. 
 
 DIAGRAM OF THE ARTICULATIONS OF THE TABSUS AND THE TARSO-METATARSUS. 
 
 5. Common scapho-cuneiforin, intercuneifomi, 
 
 and metatarso- cuneiform synovial ca- 
 vity. 
 
 6. Cubo-metatarsal synovial cavity. 
 
 1. Posterior calcaneo-astragaloid synovial cavity. 
 
 2. Calcaneo-scaphoid synovial cavity. 
 
 3. Calcaneo-cuboid synovial cavity. 
 
 4. Synovial cavity between metatarsal bone of 
 
 great toe, and internal cuneiform bone. 
 
 elasticity, the foot gains a general springiness and strength which 
 could not have resulted from a single bone. 
 
 TARSO-META- The tarsus articulates with the metatarsus in 
 
 TARSAL JOINTS. an oblique line which inclines backwards on its 
 outer side. This line is interrupted at the joint of the middle 
 cuneiform bone and the second metatarsal bone. Here there is a 
 deep recess, so that the base of this metatarsal bone is wedged in 
 between the internal and external cuneiform bones. 
 
SYNOVIAL MEMBRANES OF THE TARSUS. 577 
 
 These joints are maintained in position, above, by dorsal tarso- 
 metatarsal ligaments, and, below, by plantar ligaments. Inter- 
 osseous ligaments also pass between the wedge bones, keeping 
 them in their respective places (fig. 137). 
 
 The metatarsal bones are connected to those at their proximal 
 and distal ends by dorsal and plantar ligaments : those at the 
 proximal extremities are very strong, and are supplemented by 
 interosseous fibres, as in the metacarpus, p. 350. 
 
 The distal extremities of the metatarsal bones are united by 
 the transverse metatarsal ligament ; this extends from the great 
 to the little toe on their plantar surfaces. 
 
 SYNOVIAL MEM- Exclusive of the ankle-joint and the phalanges 
 BRANES OF THE of the toes, the bones of the foot are provided with 
 TARSUS. g j x distinct synovial membranes ; namely 
 
 1. Between the posterior articular surface of the os calcis and 
 that of the astragalus. - 
 
 2. Between the head of the astragalus and the scaphoid, and 
 between the anterior articular surface of the astragalus and os 
 calcis. 
 
 3. Between the os calcis and the os- cuboides. . 
 
 4. Between the inner cuneiform bone and the metatarsal bone 
 of the great toe. 
 
 5. Between the scaphoid and the three cuneiform bones, and 
 between these and the adjoining bones (the great toe excepted). 
 
 6. Between the os cuboides and the fourth and fifth metatarsal 
 bones. 
 
 The joints formed between the distal ends of the metatarsal 
 bones and the phalanges of the toes, and the several inter- 
 phalangeal joints, are connected in all respects like those of the 
 fingers. See the description given in the dissection of the hand 
 (p. 351). 
 
 FP 
 
578 
 
 DISSECTION OF THE BRAIN. 
 
 MEMBRANES OF PREVIOUS to the examination of $\e brain itself, 
 THEBfiAiN. we should study the structure and uses of the 
 
 three membranes by which it is surrounded. 
 
 The first, the dura mater, has been described (p. 6). The 
 second is a serous membrane, termed the arachnoid ; the third is 
 a vascular one, termed the pia mater. 
 
 ARACHNOID This second investment forms the smooth, 
 
 MEMBRANE. polished surface of the brain, exposed after the 
 
 removal of the dura mater. It is named arachnoid, from the 
 resemblance of its texture to a spider's web. It is a serous mem- 
 brane, 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. 
 
 The opposed surfaces of this membrane are polished, and 
 lubricated by a serous fluid which diminishes friction ; since the 
 brain is moved 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 can be demonstrated as a distinct layer only in 
 a few places ; it consists of little more than a layer of squamous 
 epithelium, lining the inner aspect of the dura mater. The 
 visceral layer is colourless and transparent ; it is spread uniformly 
 over the surface of the brain, and does not dip into the furrows 
 between the convolutions. 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 places, especially at 
 the base of the brain, termed subarachnoid spaces, where the 
 arachnoid membrane can be seen distinct from the subjacent 
 pia mater. 
 
DISSECTION OF THE BRAIN. 579 
 
 STJBABACHNOID Wherever the arachnoid membrane is separated 
 SPACES AND FLUID, from the pia rnater a serous fluid (cerebro-spinal} 
 intervenes, contained in the meshes of a very delicate areolar 
 tissue. The spaces between them are termed subarachnoid. 
 They are very manifest in some places. For instance, there is 
 one well-marked space in the longitudinal fissure, where the 
 arachnoid does not descend to the bottom, but passes across the 
 edge of the falx cerebri, a little above the corpus callosum. At 
 the base of the brain, there are two of considerable size : one is 
 situated between the anterior border of the pons Varolii and the 
 commissure of the optic nerves ; the other between the cere- 
 bellum and the medulla oblongata. In the spinal cord, also, there 
 is a considerable interval occupied by fluid between the arachnoid 
 and the pia mater. The purpose of this fluid is, not only to fill 
 up space, as fat does in other parts, but mechanically to protect 
 the nervous centres from the violent shocks and vibrations to which 
 they would otherwise be liable. 
 
 The brain therefore may be said to be supported in a fluid, 
 which insinuates itself into all the inequalities of the surface, and 
 surrounds all the nerves as far as 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.* 
 This, the immediate investing membrane of the 
 brain, is extremely vascular, and composed of a 
 minute network of blood-vessels held together by delicate connec- 
 tive tissue. From its internal surface vessels pass off at right 
 angles into the interior of the brain. The pia 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 cerebro-spinal fluid varies in amount from two drachms to two ounces. It 
 is a clear, limpid fluid, slightly alkaline, containing 98'5 parts of water, and 1'5 
 parts of solid matter. The cerebro-spinal fluid of the encephalon and that of the 
 spinal cord communicate. 
 
 f The arachnoid is said to be supplied with filaments from the motor root of the 
 fifth, the facial and the spinal accessory nerves ; the pia mater by the third, sixth, 
 facial, pneumogastric, spinal accessory and sympathetic nerves. 
 
 p p 2 
 
580 
 
 DISSECTION OF THE BRAIN. 
 
 ARTERIES OP 
 THE BRAIN. 
 
 INTERNAL 
 CAROTID. 
 
 Bulb of olfactory nerve . 
 
 Second pair or optic 
 neiTe . . . 
 
 Locus perforatus anticus. 
 Tractus opticus .... 
 
 Crus cerebri 
 
 Third pair of nerves . . 
 Fourth pair of nerves . . 
 
 Fifth pair of nerves . . 
 Sixth pair of nerves . . 
 
 Pyramid 
 Olive 
 
 Vertebral artery 
 
 Anterior spinal a. 
 
 The brain is supplied with blood by the two 
 internal carotid and the two vertebral arteries. 
 
 This artery enters the skull through the carotid 
 canal in the temporal bone, and ascends very 
 
 Fro. 139. 
 
 Interior cerebral a. 
 
 Lamina cinerea. 
 Middle cerebral a. 
 Tuber cineremn. 
 Mammillary body. 
 Locus perforatus niedius. 
 Posterior cerebral a. 
 Superior cerebellar a. 
 Pons Varolii. 
 Inferior cerebellar a. 
 Seventh pair of nerves . 
 
 Eighth pair of nerves. 
 Ninth pair of nerves. 
 Cerebellum. 
 
 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 posterior com- 
 municating arteries. 
 
DISSECTION OP THE BRAIN. 581 
 
 a. The anterior cerebral artery passes forwards to reach the longi- 
 tudinal fissure between the hemispheres, curves round the front part of 
 the corpus callosum, then runs backwards along its upper surface (under 
 the name of the 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 anterior 
 communicating artery (fig. 139). 
 
 6. The middle cerebral artery, the largest branch of the internal 
 carotid, runs deeply within 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 small arteries, which pierce the locus per- 
 foratus anticus to supply the corpus striatum. 
 
 c. The posterior communicating artery proceeds directly backwards 
 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 carotid, 
 arises external to the posterior communicating artery. It runs back- 
 wards, and enters the fissure at the bottom of the middle horn of the 
 lateral ventricle, to terminate in the choroid plexus of that cavity. 
 
 VERTEBRAL This artery, a branch of the subclavian in the 
 
 ARTERY. fi r g p ar ^ o f j^ s course, winds backwards along the 
 
 arch of the atlas, and enters the skull through the foramen magnum 
 by perforating the posterior occipito-atlantoid ligament. It then 
 curves round the medulla oblongata between the hypoglossal nerve 
 and the anterior root of the first cervical. At the lower border 
 of the pons Varolii, the two arteries unite to form a single trunk 
 the ' basilar ' which is lodged in the groove along the middle 
 of the pons, and bifurcates at its upper border into the 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 run along the median 
 fissures of the front and back surfaces of the spinal cord. 
 
 c. The inferior cerebellar artery, sometimes a branch of the basilar, 
 but more frequently of the vertebral, passes backwards between the hypo- 
 
582 DISSECTION OF THE BEAIN. 
 
 glossal and pneumogastric nerves, and divides into two branches, which 
 are distributed to the inferior 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, 
 to be distributed to the internal ear. 
 
 b. The anterior cerebellar, which supplies the front part of the lower 
 surface of the cerebellum and anastomoses with the other cerebellar 
 arteries. 
 
 c. The superior cerebellar, which is distributed to the upper surface 
 of the cerebellum ; the valve of Vieussens and part of the velum inter- 
 positum. 
 
 d. The two posterior cerebral, the terminal branches into which the 
 basilar artery divides, run outwards and backwards, in front of the third 
 nerve. They wind round the crura cerebri and divide into numerous 
 branches which supply the under surface of the posterior cerebral lobes, 
 and ultimately inosculate with the other cerebral arteries. Each gives 
 off a small posterior choroid artery, distributed to the velum inter- 
 positum, and choroid plexus. 
 
 CIRCLE OF This important arterial inosculation (fig. 139) is 
 
 WILLIS. 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 serves to mitigate 
 the force of the heart's action ; and the circle of Willis provides a 
 free supply of blood from other vessels, in case any accidental cir- 
 cumstance should stop the flow of blood through any of the more 
 direct channels.* 
 
 * In many of the long-necked herbivorous quadrupeds a 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. Tho arteries, as they enter the skull, divide 
 into several branches, which again unite and form a remarkable network of 
 arteries, called by Galen, who first described it, the 'rete mirabil-e.' The object of this 
 evidently is to moderate the rapidity with which the blood would otherwise 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. 
 
DISSECTION OF THE BBAIN. 583 
 
 PECULIARITIES Besides the circle of Willis, there are other 
 
 OF THE CEREBRAL peculiarities relating to the circulation of the 
 CIRCULATION. blood in the brain : namely, the length and tor- 
 
 tuosity of the four great arteries as they enter the skull ; their 
 passage through tortuous bony canals ; the spreading of their rami- 
 fications in a very delicate membrane, the pia mater, before they 
 enter the substance of the brain ; the minuteness of the capillaries, 
 and the extreme thinness of their walls ; the formation of the venous 
 sinuses (p. 8), which do not accompany the arteries ; the chordae 
 Willisii in the superior longitudinal sinus ; the absence of valves in 
 the sinuses ; and the confluence of no less than six sinuses, forming 
 the torcular Herophyli, at the internal occipital protuberance. 
 
 GENERAL Di- The mass of nervous substance contained within 
 
 VISION OF THE the cranium, comprised under the common term 
 BEAIN - brain (encephalon), is divided into four parts : the 
 
 cerebrum, which occupies the whole of the upper part of the 
 cranial cavity ; the cerebellum, or smaller brain, which occupies 
 the space below the tentorium cerebelli ; the pons Varolii, or the 
 quadrilateral mass of white fibres which rests upon the basilar 
 process of the occipital bone ; and the medulla oblongata, situated 
 below the pons, and continuous with the spinal cord (fig. 142). 
 
 The weight of the entire encephalon bears a proportionate re- 
 lation to the intellectual power. The result of observations shows 
 that it averages in males about 50 ounces, and in females about 
 44 ounces. 
 
 MEDULLA OB- This term is applied to that part of the cerebro- 
 
 LONGATA. spinal axis which is placed below the pons Varolii, 
 
 and is continuous with the spinal cord on a level with the upper 
 border of the atlas. It is slightly pyramidal in shape, with the 
 broad part above. It lies on the basilar groove of the occipital 
 bone, and descends obliquely backwards through the foramen 
 magnum. Its posterior surface is received into the fossa (vallecula) 
 between the hemispheres of the cerebellum. It is about an inch 
 and a quarter in length, and nearly an inch thick at its broadest 
 part. 
 
 In front and behind, the medulla is marked by a median 
 
584 
 
 DISSECTION OP THE BRAIN. 
 
 fissure, the anterior and posterior median fissures, which are the 
 continuations of the median fissures of the spinal cord. The 
 anterior ends, below the pons Varolii, in a cul-de-sac, termed the 
 foramen cczcum, and is occupied by a process of pia mater. The 
 posterior runs along the floor of the fourth ventricle as a shallow 
 median groove. 
 
 The surface of the medulla is marked out on each side into 
 four longitudinal columns, which receive the following names 
 
 FIG. 140. 
 
 1. Gasserian ganglion. 
 
 2. Motor root of the 
 
 fifth n. 
 
 C. Crus cerebri. 
 P. V. Pons Varolii. 
 P. Anterior pyramid. 
 O. Olive. 
 
 B. Restiform tract or 
 body. 
 
 3. Third n. 
 
 4. Aroiform fibres. 
 
 5. Sensitive root of the 
 
 fifth n. 
 
 6. Sixth n. 
 
 7. Two divisions of the 
 
 seventh n. 
 
 8. Three divisions of 
 
 the eighth n. 
 
 9. Ninth or hypoglos- 
 
 sal n. 
 
 DIAGRAM OF THE FRONT SURFACE OF THE MBDULLA OBLONGATA. 
 
 from before backwards : the anterior pyramids, the olivary bodies, 
 the restiform bodies, and the posterior pyramids. 
 
 The anterior pyramids are two columns of white matter, 
 narrow below, but increasing gradually in breadth as they 
 ascend towards the pons. At this part they become constricted, 
 and may be traced through the pons into the crura cerebri. 
 The fibres of which they are in the main composed are derived 
 from the anterior columns of the spinal cord, and consist there- 
 fore of motor fibres. On separating the pyramids about an inch 
 
DISSECTION OP THE BRAIN. 
 
 585 
 
 below the pons, bundles of nerves are seen decussating across 
 the anterior fissure (fig. 140). This is the explanation of cross 
 paralysis i.e. when one side of the brain is injured, the loss 
 of motion is manifested on the opposite side of the body.* This 
 decussation, which consists of three or four bundles on each side, 
 involves only the inner fibres of the pyramid ; the outer fibres 
 ascend through the pons without crossing. The decussating 
 fibres are the continuations upwards of the deep fibres of the 
 
 FIG. 141. 
 
 DIAGRAM OF THE FOUETH VENTHICLE AND BESTIl'OEM BODIES. 
 
 1. Thalamus options. 
 
 2. Nates and testes. 
 
 3. Origin of fourth nerve. 
 
 4. Processns a cerebello ad testes. 
 
 5. Restiform bodies diverging. 
 
 6. Origins of seventh or auditory nerve. 
 
 lateral columns of the spinal cord, which here come forwards to 
 the surface, and push aside the anterior columns. 
 
 The olivary bodies are the two oval eminences situated on the 
 outer side of the anterior pyramids, from which they are separated 
 by a shallow depression. They do not ascend quite as high as the 
 pons. They consist externally of white matter ; and, when cut 
 
 * The phenomenon of cross paralysis of sensation is explained by the fact made 
 out by Brown-S6quard, that the paths of sensory impressions cross each other in the 
 grey matter of the cord. 
 
586 DISSECTION OP THE BEAIN. 
 
 into, their interior presents an undulating line of yellowish-brown 
 colour, called from its zigzag shape the corpus dentatum. This, 
 which is sometimes called the olivary nucleus, forms an interrupted 
 circle, incomplete at its upper and inner side, so that it nearly 
 isolates the white matter within. The small grey mass placed above 
 the corpus dentatum, and similarly composed of grey matter, is 
 called the accessory olivary nucleus. At the lower part of the 
 olivary body, some white fibres may be observed arching round 
 from the anterior median fissure, constituting the ardform, fibres 
 of Eolando. 
 
 The restiform bodies, situated to the outer side of and behind 
 the olivary bodies, are the continuations upwards of the posterior 
 columns of the spinal cord. As they ascend they diverge and 
 pass into the cerebellum, constituting its inferior peduncles 
 (fig. 141). Owing to this divergence, the grey matter of the 
 medulla is exposed, so that the floor of the fourth ventricle (of 
 which the restiform bodies assist in forming the lateral boundaries) 
 is mainly composed of grey matter. The restiform bodies consist 
 of white fibres derived from the posterior and lateral columns 
 of the spinal cord ; in its interior is some grey matter continuous 
 with that in the posterior part of the cord. 
 
 The posterior pyramids are the two slender white columns on 
 each side of the posterior median fissure. Ascending, they 
 diverge and thus form the apex of the fourth ventricle. At their 
 point of separation the posterior pyramids enlarge, and form the 
 processus clavatus ; after which they diminish in size, and run up 
 with the restiform bodies, which, however, they soon leave and are 
 continued upwards into the cerebrum along the floor of the fourth 
 ventricle. 
 
 Emerging from the anterior median fissure may be noticed 
 some superficial transverse white fibres which cross below the 
 lower extremity of the olivary bodies, and sometimes also the 
 anterior pyramids ; these are known as the ardform, fibres of 
 Rolando (fig. 140). They are probably connected with white 
 fibres which run horizontally, constituting an imperfect septum 
 between the two halves of the medulla, and may be seen when a 
 
DISSECTION OF THE BEAIN. 587 
 
 longitudinal section is carefully made through its middle. The 
 majority of these septal fibres enter the olivary bodies, and then 
 emerging through the grey matter of the corpus dentatum, 
 become continuous with the fibres of the restiform bodies and 
 lateral tracts ; others pass out from the posterior fissure and 
 wind round the restiform bodies. These latter fibres are the trans- 
 verse strice, seen on the floor of the fourth ventricle, some of which 
 form the roots of the auditory nerves. 
 
 PONS VAROLII This convex eminence of transverse white 
 
 OR GREAT COMMIS- fibres (p. 584) is situated at the base of the 
 SURE OF THE CE- brain, immediately above the medulla oblongata. 
 It rests upon the basilar groove of the occipital 
 bone, and in its antero-posterior diameter measures rather more 
 than an inch. The upper margin is convex, and arches over the 
 crura cerebri ; the lower is nearly straight, being separated from 
 the medulla by a transverse groove. On each side the pons 
 becomes narrower, in consequence of the transverse fibres being 
 more closely aggregated ; these enter the anterior part of the 
 cerebellum, constituting its middle crus. Along the middle 
 runs a shallow groove which lodges the basilar artery. If the 
 pia mater be removed, we observe how the superficial fibres 
 pass transversely, to connect the two hemispheres of the cere- 
 bellum. Throughout the mammalia the size of the pons bears a 
 direct ratio to the degree of development of the lateral lobes of 
 the cerebellum ; therefore it is larger in man than in any other 
 animal.* 
 
 When the superficial transverse fibres are dissected off, the 
 longitudinal fibres of the anterior pyramids are seen passing up 
 beneath them to enter the crura cerebri, like a river under a 
 bridge, hence its name of pons. These pyramidal fibres are 
 separated into yet smaller bundles by deeper transverse fibres, 
 which, like the superficial transverse ones, are continued into the 
 cerebellum. 
 
 Besides the transverse and longitudinal fibres just described, 
 
 * Birds, reptiles, and fishes have no pons, as there are no lateral lobes to the 
 cerebellum. 
 
588 DISSECTION OF THE BRAIN. 
 
 the pons contains a considerable amount of grey matter, which is 
 distributed between the transverse and longitudinal fibres. 
 
 The pons, like the medulla oblongata, has an imperfect 
 median septum, composed of horizontal fibres, some of which at its 
 anterior border surround the crura cerebri. 
 
 The cerebrum in man is so much more de- 
 
 CKRFBRUM 
 
 veloped than the other parts of the encephalon 
 that it completely overlies them, and forms by far the largest 
 portion. It is oval in form, and convex on its external aspect. It 
 is divided in the middle line into two symmetrical parts, termed 
 the right and left hemispheres, by the deep longitudinal fissure, 
 which is occupied by the falx cerebri (p. 7).* The cerebrum is 
 composed of numerous parts viz., of certain internal ganglionic 
 masses, the corpora striata, optic thalami, and corpora quadri- 
 FIG. 142. gemina; of commissural white fibres, 
 
 the fornix, corpus callosum, and the com- 
 missures of the third ventricle; of the 
 pineal arid pituitary bodies ; and, lastly, of 
 the two lateral hemispheres, which overlie 
 and conceal the parts previously men- 
 tioned. 
 
 The cerebrum rests upon the anterior 
 and middle fossae of the base of the skull, 
 and the tentorium cerebelli. There are 
 
 DIAGRAM OF THE GENERAL 
 
 DIVISIONS OF THE BBAiN. three surfaces to each hemisphere : an 
 i, 2, 3. Anterior, middle, and poste- external or convex i an inner or median : 
 
 rior lobes of the cerebrum. 
 
 4. cerebellum. and an inferior, interrupted by the fissure 
 
 5. Pons Varolii. ^ ' 
 
 6. Medulla oblongata. of Sylvius. 
 
 By widely separating the two hemispheres at the longitudinal 
 fissure (the brain being in its natural position), we discover that 
 they are connected in the middle by the transverse white com- 
 
 * Examples are occasionally met with, where the longitudinal fissure is not 
 exactly in the middle line, the consequence of which want of symmetry is, that one 
 hemisphere is larger than the other. Bichat (' Recherches physiologiques sur la \ r ie 
 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 proye the error of his theory. 
 
DISSECTION OF THE BRAIN. 
 
 589 
 
 missure, called the corpus callosum. In front of, and behind this 
 white mass, the fissure extends to the base of the brain. 
 
 The surface of each hemisphere is mapped out by tortuous 
 eminences termed convolutions (gyri), separated from each other 
 by deep furrows, sulci. Many of the furrows are occupied by 
 the large veins in their course to the sinuses ; others are filled 
 with subarachnoid fluid. The convolutions are folds of the brain, 
 for the purpose of increasing the extent of the surface for the 
 grey nerve-substance. They are not symmetrical on both sides, 
 although they follow a somewhat similar arrangement. Their 
 number, arrangement, and depth, vary somewhat in different 
 individuals, and, to a certain extent, may be considered an 
 index of the degree of intelligence-* 
 
 Since the grey matter forms a sort of bark round the white 
 substance, it is often called the cortical substance. The depth 
 of the sulci between the convolutions varies in different brains, 
 from an inch to half an inch ; hence it follows that two brains 
 of equal size may be very unequal in point of extent of surface 
 for the grey matter, and therefore in amount of intellectual 
 capacity. Under the microscope the cortical layer is seen to 
 consist of four layers, two grey alternating with two of white, 
 the external layer being always white.f 
 
 Some of the sulci, from their depth, regularity, and early 
 period of development, are termed the primary fissures, and map 
 out the surface of the cerebrum into its different lobes. Of these 
 there are three : the fissure of Sylvius, the fissure of Rolando 
 or central fissure, and the parieto-occipital fissure (fig. 143). 
 
 * 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 develop- 
 ment and arrangement into groups as we ascend to the higher classes, should 
 consult Leuret, 'Anatomie comparee duSysteme Nerreux considered dans ses Kapports 
 avec Tlntelligence,' Paris, 1839 ; alsoFoville, 'Traite de 1'Anat. du Systeme Nerveux,' 
 &c., Paris, 1844. The convolutions of the human brain have been described by 
 Ecker, 'On the Convolutions of the Human Brain,' 1873; and by Turner, 'The 
 Convolutions of the Human Brain, topographically considered,' Edin. 1866. 
 
 f Six layers may be demonstrated in some situations, chiefly near the corpus 
 callosum and the occipital lobe. For an account of these laminae see Lockhart 
 Claske, 'Proceed. Eoyal Society,' 1863. 
 
590 
 
 DISSECTION OP THE BRAIN. 
 
 The fissure of Sylvius is seen on the base of the cerebrum, 
 and receives the lesser wing of the sphenoid bone. It curves 
 outwards as a deep cleft, and divides into two rami ; an as- 
 cending or vertical, about an inch in length, and a posterior or 
 horizontal ramus, which passes backwards, and ends about the 
 middle of the hemisphere. 
 
 iio. 143. 
 
 YIEW OF THE CONVOLUTIONS AND FISSURES OF THE EXTERNAL SURFACE OF THE 
 BRAIN (LEFT SIDE). 
 
 A. Fissure of Rolando. 
 
 u. Fissure of Sylvius. 
 
 c. Inter-parietal fissure. 
 
 P.O. Parieto-occipital fissure. 
 
 c.m. Calloso-marginal fissure. 
 
 F. Frontal lobe. 
 
 p. Parietal lobe. 
 
 o. Occipital lobe. 
 
 T.S. Temporo-sphenoidal lobe. 
 
 A.F. Ascending frontal convolution. 
 
 A.P. Ascending parietal convolution. 
 
 /i,/2,/3. Superior, middle, and inferior frontal 
 
 convolutions, separated by the superior 
 and inferior frontal sulci. 
 
 pi, yl. Superior and inferior parietal convolu- 
 tions, separated by the inter-parietal 
 fissure. 
 
 of, o2, o3. Superior, middle, and inferior occi- 
 pital convolutions, separated by the occi- 
 pital fissures. 
 
 ti, t2, <3. Superior, middle, and inferior tem- 
 poro-sphenoidal convolutions, separated 
 by the superior and inferior temper o- 
 sphenoidal fissures. 
 
 The fissure of Rolando or central fissure runs obliquely over 
 the outer surface of the hemisphere. It commences close to the 
 
DISSECTION OP THE BEAIN. 591 
 
 longitudinal fissure about its middle, then runs downwards and 
 forwards, and terminates a little above the fork of the Sylvian 
 fissure. 
 
 The parieto-occipital fissure is seen on the median surface 
 of the hemisphere towards its posterior part. It begins on its 
 median surface about half an inch behind the corpus callosum, 
 then ascends nearly vertically, and ends on the external aspect 
 of the cerebrum about an inch from the longitudinal fissure.* 
 
 Other important fissures besides the primary just described 
 are seen on the cerebral surface. They are chiefly found on the 
 median aspect of the hemisphere, and are as follows (fig. 144) : 
 
 The calloso-marginal fissure runs nearly parallel with the 
 anterior two-thirds of the corpus callosum, then, changing its 
 direction, it ascends obliquely and terminates on the external 
 aspect of the hemisphere, where rt forms a deep notch immedi- 
 ately behind the fissure of Kolando. 
 
 The calcarine fissure, also seen on the median surface, begins 
 close to the posterior border of the cerebrum, and then, running 
 nearly horizontally forwards, terminates below the corpus callosum. 
 Midway in its course it is joined at an acute angle by the parieto- 
 occipital fissure. 
 
 The primary fissures form the boundaries of the various lobes 
 of which each hemisphere is composed. 
 
 Thus the frontal lobe is that part of the cerebrum anterior 
 to the fissure of Rolando on the external surface, and the calloso- 
 marginal fissure on the median. The parietal lobe is placed 
 between the fissure of Rolando and the external parieto-occipital 
 fissure. 
 
 The occipital lobe consists of the posterior part of the hemi- 
 sphere behind and below the parieto-occipital fissure. The tem- 
 poro-sphenoidal lobe is bounded above by the horizontal ramus 
 of the Sylvian fissure, and forms that part of the hemisphere 
 which occupies the middle cerebral fossa. 
 
 The island of Reil or the central lobe lies deep in the fissure 
 
 * The fissure of Rolando is first seen about the fifth month of foetal life ; the 
 parieto-occipital fissure, between the fourth and fifth month. 
 
592 
 
 DISSECTION OP THE BRAIN. 
 
 of Sylvius. It consists of a number of hidden convolutions 
 (gyri operti} connected; with those adjoining it, and corresponds 
 to the under surface of the corpus striatum. The frontal lobe 
 is on its external surface divided by two frontal fissures into a 
 superior, middle, and inferior frontal convolution (fig. 143). 
 
 The only fissure of the parietal lobe is the inter-parietal sulcus, 
 which separates the upper from the lower parietal convolution, 
 which latter is occasionally divided into the supra-marginal and 
 angular gyrus ; the one being above, the other behind the fissure of 
 
 Fie. 144. 
 
 PO 
 
 CONVOLUTIONS AND FISSURES OF THE MEDIAN' AND TENTOBIAL SURFACES OF RIGHT 
 
 HEMISPHERE. 
 
 c c. Corpus callosum. 
 
 A F. Ascending frontal convolution. 
 
 A p. Ascending parietal convolution. 
 
 p o. Parieto-occipital fissure. 
 
 p c. Praecuneus or quadrate lobe. 
 
 c Cuneus. 
 
 c Calcarine fissure. 
 
 Clf. Collateral fissure. 
 
 o.p. Gyrus foraicatns. 
 
 cm. Calloso-marginal fissure. 
 
 fi.- Supei ior frontal or marginal convolution. 
 
 O.T. Optic thalamus. 
 
 p. Pituitary body. 
 
 rfc. Dentate convolution. 
 
 to4. Gyrus occipito-temporalis lateralis. 
 
 to5. Gyrus occipito-temporalis medialis. 
 
 Sylvius. Behind the fissure of Eolando is the ascending parietal 
 convolution, which is usually continuous with the ascending frontal 
 convolution, above and below the fissure. 
 
 The occipital lobe is composed of a superior, middle, and in- 
 ferior occipital convolution, separated by ill-defined sulci, and 
 connected with some parietal and temporo-sphenoidal convolutions 
 
DISSECTION OF THE BRAIN. 593 
 
 by the annectant gyri. The temporo-sphenoidal lobe is traversed 
 by two parallel fissures, which divide it into a superior, middle, 
 and inferior temporo-sphenoidal convolution. In front of the 
 under aspect of this lobe, there is the undnate or hippocampal 
 convolution, which is continuous with the gyrus fornicatus. In this 
 situation also we find two fissures, the hippocampal and the col- 
 lateral, the former of which corresponds to the hippocampus major, 
 the latter to the eminentia collateralis. The remaining convolu- 
 tions are seen on the median surface of the hemisphere, and com- 
 prise the gyrus fornicatus, which coursesround the corpus callosum; 
 the cuneus, situated between the parieto-occipital and calcarine 
 fissures ; and the prcecuneus or quadrate lobe placed in front of the 
 parieto-occipital fissure. 
 
 NOMENCLATURE The several objects seen at the base of the brain 
 
 OF THE PAETS AT in the middle line should now be examined, pro- 
 
 THEBASE OF THE ceeding in order from the front (fig. 139, p. 580). 
 
 In this description the cerebral nerves are omitted. 
 
 These will be examined hereafter. 
 
 Tn the middle line, dividing the frontal lobes, is the longitudinal 
 fissure. By gently separating these lobes, we expose the corpus cal- 
 losum, 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, the peduncle of the corpus callosum. Extending from 
 the corpus callosum to the optic commissure is a thin grey layer, 
 the lamina cinerea. Between the frontal and temporo-sphenoidal 
 lobes is the fissure of Sylvius, which lodges the middle cerebral 
 artery. 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 is the locus perforatus* 
 anticus. Immediately behind the optic commissure is a slight 
 prominence of grey matter, the tuber cinereum; from this de- 
 scends a conical tube of reddish colour, the infundibulum, to the 
 apex of which is attached the pituitary body. Behind the tuber 
 
 * Called ' perforatus ' from its being perforated by a number of blood-vessels, for 
 the supply of the corpus striatum. 
 
 QQ 
 
594 DISSECTION OF THE BRAIN. 
 
 cinereum are two round white bodies, the corpora mammillaria. 
 Posterior to these is the locus perforatus posticus, which is bounded 
 behind by the pons, and laterally by the two diverging crura cere- 
 bri, two round cords of white substance, which emerge from the 
 anterior border of the pons. Winding round the outer side of each 
 crus is a soft white band, the optic tract. 
 
 Examine now in detail the various objects above enumerated, 
 most of which are shown in fig. 139. 
 
 The lamina cinerea is a thin layer of grey substance, which 
 connects the corpus callosum, and the optic commissure ; it passes 
 above this and becomes continuous with the tuber cinereum. If 
 the lamina be torn, which is very easily done, an aperture is made 
 into the third ventricle. 
 
 The Locus perforatus anticus, placed to the inner side of the 
 commencement of the fissure of Sylvius, is composed partly of 
 grey substance ; crossing it is seen a broad white band, the 
 peduncle of the corpus callosum. 
 
 The tuber cinereum is a prominence of grey matter immediately 
 behind the optic commissure, and from it a conical tube of reddish 
 colour, the infundibulum, descends to the pituitary body. This 
 body, which occupies the sella turcica, is of reddish-brown colour, 
 and consists of two lobes; the anterior, the larger, is concave 
 behind to receive the posterior lobe. It weighs from five to ten 
 grains, and on section resembles in structure the thyroid gland, 
 being composed of reticular tissue with numerous cavities filled 
 with nucleated cells and granular matter. 
 
 The corpora, albicantia or mammillaria are two round white 
 bodies, which are formed by the curl of the anterior crura of 
 the fornix. 
 
 The locus perforatus posticus,* is a depression of grey matter, 
 the surface of which is penetrated by small vessels which supply 
 the optic thalami. 
 
 ORIGIN OF THE The cerebral nerves are given off in pairs, named 
 CEREBRAL the first, second, third, &c., according to the order 
 
 NERVES. ' j n ^hich they appear, beginning from the front. 
 
 * POES Tarini. 
 
DISSECTION OF THE BKAIN. 
 
 595 
 
 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 larger root of the fifth, the glosso-pharyngeal, 
 and the pneumogastric ; others, again, are nerves of motion as 
 the third, the fourth, the smaller root of the fifth, the sixth, the 
 facial division of the seventh, the spinal accessory, and the hypo- 
 glossal. 
 
 FIG. 145. 
 
 1. Olfactory n. 
 
 2. Optic n. 
 
 3. Crus cerebri. 
 
 4. Section of cms to 
 
 show locus niger. 
 
 6. Corpus geniculatum 
 externum. 
 
 6. Corpus geniculatnm 
 
 internum. 
 
 7. Corpora quadri- 
 
 geinina. 
 
 8. Thalamus options. 
 
 9. Tractns options. 
 10. Corpus callosum. 
 
 DIAGRAM OF THE ORIGINS OF THE OLFACTORY AND OPTIC NERVES. 
 
 FIRST PAIR OR 
 OLFACTORY 
 NERVES. 
 
 The olfactory nerve is triangular on section, the 
 apex of the triangle being lodged in a furrow 
 {olfactory sulcus) between the convolutions. It 
 proceeds straight forwards under the frontal lobe, and terminates 
 in the olfactory bulb, which lies on the cribriform plate of the 
 ethmoid bone. 
 
 The olfactory lobe is oval, of a reddish-grey colour, and very soft 
 consistence, owing to the large amount of grey matter contained 
 in it. It gives off from its under surface about twenty branches, 
 
 Q Q 2 
 
596 DISSECTION OF THE BRAIN. 
 
 which pass through the foramina of the cribriform plate.* For 
 the description of these, see p. 233. 
 
 The nerve arises by three roots an outer and an inner, com- 
 posed of white matter, and a middle, composed of grey (p. 595). 
 
 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. Its deeper origin has been traced to the 
 optic thalamus and a nucleus in the anterior part of the temporo- 
 sphenoidal lobe. 
 
 The inner root arises from the posterior extremity of the in- 
 ternal convolution of the frontal lobe, and thence may be traced to 
 the gyrus fornicatus. 
 
 The middle, or grey root, arises from the grey matter of the 
 sulcus, in which the nerve is lodged, and from the grey matter 
 of the locus perforatus anticus; to see it, therefore, the nerve 
 should be turned backwards. It contains white fibres in its 
 interior, which have been traced to the corpus striatum. 
 
 SECOND PAIR The optic tracts arise from the corpora quadri- 
 
 OR OPTIC. gemina, the corpora geniculata, and the optic 
 
 thalami (p. 595). They wind round the crura cerebri, with which 
 they are connected by their anterior borders, and join in the 
 middle line to form the optic commissure. This commissure rests 
 upon the sphenoid bone in front of the sella turcica ; and from it 
 each optic nerve, invested by its 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 
 
 * 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 crus 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 development of the olfactory lobes. Again, in many animals, these lobes are 
 actually larger than the cerebral, and contain in their interior a cavity which com- 
 municates with the lateral ventricles. According to Tiedemann, this cavity exibts 
 even in the human foetus at an early period. 
 
DISSECTION OP THE BRAIN. 597 
 
 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. 600).* 
 
 THIRD PAIR OR ^ ne apparent origin of the third nerve is from 
 MOTORES Ocu- the inner side of the eras cerebri, immediately in 
 I.ORUM. front of the pons. Some of its roots, however, 
 
 pass through the locus niger and the tegmentum of the crus, 
 to reach a grey nucleus beneath the iter a tertio ad quartum 
 ventriculum and below the corpora quadrigemina (p. 595). It 
 passes through the sphenoidal fissure and supplies all the muscles 
 of the orbit, except the superior oblique and the rectus externus. 
 
 FOURTH PAIR The fourth nerve arises from the upper surface 
 
 ORTROCHLEAR of the valve of Vieussens (p. 612). Here it 
 divides into three sets of fibres : one, ascending, 
 passes to the roof of the aqueduct of Sylvius ; another, decussating, 
 passes over to the opposite side to join the ascending fibres ; and 
 a third, or descending, which rises from the floor of the fourth 
 ventricle close to the locus cseruleus. It runs obliquely outwards, 
 winds round the crus cerebri, enters the orbit through the sphe- 
 noidal fissure, and supplies the superior oblique. 
 
 FIFTH PAIR OR The fifth nerve consists of two roots, both of 
 which arise apparently from the outer side of the 
 
 pons Varolii (p. 584) ; but their real origin is 
 deeper. The smaller and anterior of the two roots, consisting of 
 motor fibres only, may be traced to the outer side of the fourth 
 ventricle, and to a grey nucleus at the lower part of the medulla ; 
 the posterior and larger root consisting of purely sensory fibres, 
 may be traced to a mass of nerve-cells in connection with the grey 
 tubercle of Eolando, and also to the middle of the floor of the 
 fourth ventricle. The nerve proceeds forwards over the apex of 
 the petrous portion of the temporal bone ; here is developed, upon 
 
 * This decussation was ingeniously supposed by Dr. Wollaston ('Philos. Trans, of 
 the Royal Society,' 1824) 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. 
 
598 DISSECTION OF THE BRAIN. 
 
 the sensitive root, the Grasserian ganglion. The root then divides 
 into three branches the ophthalmic, which passes through 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 sensation 
 upon the parts they supply, which comprises the entire face and 
 sides of the 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 The sixth nerve emerges from the groove be- 
 ABDUCENTES. tween the pons and the anterior pyramid (p. 584), 
 
 with both of which it is connected. Its deep origin has been 
 traced to a grey nucleus of nerve-cells in the floor of the fourth 
 ventricle. It leaves the skull through the sphenoidal fissure, and 
 supplies the rectus externus of the eye. 
 
 SEVENTH PAI ^ e seventh comprises two nerves the portio 
 
 dura, or motor nerve of the face, and the portio 
 mollis, or auditory nerve. The two nerves, of which the portio 
 dura is the more internal and anterior, arise apparently from the 
 lower border of the pons Varolii (p. 584). The deep origin of 
 the portio dura is stated to pass through the medulla to the grey 
 nucleus in the floor of the fourth ventricle near the origin of the 
 sixth nerve. The deep origin of the portio mollis is from the 
 internal auditory nucleus in the floor of the fourth ventricle. The 
 nerve then passes outwards, and enters the meatus auditorius 
 internus in company with the portio dura. For the further 
 description of the portio dura, see p. 90. The auditory nerve 
 divides at the bottom of the meatus auditorius internus into 
 cochlear and vestibular branches, which are distributed to the 
 internal ear. 
 
 EIGHTH PAIR ^is comprises three nerves the glosso- 
 
 phai*yngeal, the pneumogastric, and the nervus 
 
 accessorius (p. 580). The glosso-pharyngeal nerve arises by several 
 
 filaments from the restiform body of the medulla, through which 
 
 they may be traced to a grey nucleus in the outer part of 
 
DISSECTION OF THE BRAIN. 599 
 
 the floor of the fourth ventricle, close to the nucleus for the 
 vagus. 
 
 The pneumogastric nerve arises by numerous filaments which 
 pass to a grey nucleus in the floor of the fourth ventricle, close to 
 the middle line. 
 
 The nervus accessorius is composed of two parts an upper or 
 accessory portion, which arises from the medulla ; and a, lower or 
 spinal portion, which arises from the spinal cord. The accessory 
 fibres may be traced to the nucleus at the apex of the calamus 
 scriptorius. The spinal portion 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 behind the 
 ligamentum denticulatum, through the foramen magnum, into 
 the skull, and joins the accessory part. The nervus accessorius 
 then passes through the foramen j ugulare with the pneumogastric 
 and glosso-pharyngeal nerves. The glosso-pharyngeal is distri- 
 buted to the mucous membrane of the pharynx, and back of the 
 tongue (p. 224). The pneumogastric is distributed to the 
 pharynx, the larynx, the heart and lungs, the oesophagus, and 
 stomach. The nervus accessorius supplies the sterno-mastoid, and 
 the trapezius. For the further description of these nerves, see 
 pp. 225, 226. 
 
 NINTH PAIR OB This nerve arises by several filaments from the 
 HrroGLossAL. medulla, along the groove between the anterior 
 pyramid and the olive. Its fibres may be traced to a long grey 
 nucleus, which forms an eminence in the floor of the fourth ven- 
 tricle in front and to the inner side of the vagal nucleus. It 
 leaves the skull through the anterior condyloid foramen, and is 
 distributed to the muscles of the tongue and depressors of the os 
 hyoides and larynx. 
 
 DISSECTION OF The brain should now be laid on its base. By 
 
 gently separating 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. 
 
600 
 
 DISSECTION OP THE BRAIN. 
 
 Slice off the hemispheres down to the level of the corpus 
 callosum. The cut surface presents a mass of white substance 
 WHITE AND surrounded by a tortuous layer of grey matter, 
 GREY MATTER. about one-eighth of an inch in thickness. 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. 
 
 FIG. 146. 
 
 FIG. 147. 
 
 UPPER SURFACE OF COR- 
 PUS CALLOSUM. 
 
 1,1. Linese transversse. 
 
 2. Raphe. 
 
 3, 3. Anterior cerebral a. 
 
 DIAGRAM OF LAMINA CINEREA. 
 
 1, 1. Peduncles of corpus callosum. 
 
 2. Lamina cinerea. 
 
 3. Commissure of optic nerves. 
 
 CORPUS CALLO- 
 
 SUM. 
 
 This transverse portion of white substance is 
 the chief connecting medium between the two 
 hemispheres, and is called the great transverse commissure of the 
 cerebrum. It is about four inches long, and is rather nearer to 
 the front than to the back part of the brain. It is, moreover, 
 thicker at the ends than in the middle. Its surface is slightly 
 arched from before backwards. A shallow groove, called the 
 raphe, runs along the middle of its upper surface (fig. 146) ; in a 
 
DISSECTION OF THE BRAIN. 
 
 fresh brain, two longitudinal white tracts, named the nerves of 
 Landsi, run parallel to it ; and external to these again are two 
 other longitudinal fibres, stride longitudinales later ales. 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. 
 
 FIG. 148. 
 
 Foramen of Monro . 
 
 Middle commissure . 
 Anterior commissure. 
 Lamina cinerea . . 
 
 Optic nerve 
 
 Pituitary gland 
 
 Infundibulnm 
 Tuber cinereum 
 Corpus mammillare 
 Locus perforatus posticus 
 
 Tons Varolii 
 
 Velum interpositum. 
 Thalamus opticus. 
 Pineal gland. 
 Posterior commissure. 
 Nates. 
 
 Iter a tertio ad qnar- 
 
 tum ventriculum. 
 Valve of Vieussens. 
 
 Fourth ventricle. 
 
 Arachnoid membrane 
 (reflected;. 
 
 Medulla oblongata 
 VERTICAL SECTION THROUGH THE CORPUS CALLOSUM, AND PARTS BELOW. 
 
 The anterior part of the corpus callosum turns downwards 
 and backwards, forming a bend called its genu. The inferior 
 part of this bend rostrum becomes gradually thinner and 
 narrower, and terminates 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. 147). The posterior 
 part of the corpus callcsum terminates in a thick, round border 
 which is free, and beneath it the pia mater enters the interior of 
 
602 DISSECTION OP THE BRAIN. 
 
 the ventricles. A satisfactory view cannot be obtained of the arch 
 formed by the corpus callosum, 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 preceding figure.* 
 
 Connected with the under surface of the posterior part of the 
 corpus callosum is the fornix, which separates from it in front, 
 the two structures being connected by a vertical septum the 
 septum, lucidum. 
 
 LATERAL VEN- A longitudinal incision should be made on each 
 
 TRICIJSS. s i(] e through the corpus callosum about half an 
 
 inch from its median raphe. Care must be taken not to cut too 
 near the middle line, in order to preserve the delicate partition 
 which descends from the under surface of the corpus callosum, and 
 separates the ventricles from each other. Two cavities, called the 
 lateral ventricles, will thus be exposed, one in each cerebral hemi- 
 sphere, and they should afterwards be laid open throughout 
 their whole extent. Their general form should be first examined ; 
 then the several objects seen in them. 
 
 The lateral ventricles are two serous cavities, one in each 
 hemisphere of the brain. They are occasioned by the enlargement 
 and folding backward of the cerebral lobes over the other parts of 
 the central nervous axis. They contain a serous fluid, which, 
 even in a healthy brain, sometimes exists in considerable quan- 
 tity ; when greatly in excess it constitutes one form of the disease 
 termed hydrocephalus. The ventricles are lined with ciliated 
 epithelium, laid upon a layer of neuroglia ; a term which has been 
 applied to that peculiarly delicate connective tissue found through- 
 out the brain and spinal cord. 
 
 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 corpus callosum is more or less developed in all mammalia, but is absent 
 in birds, reptiles, and fish. It has been absent in the human subject without any 
 particular mental de6ciency. See cases recorded by Reil, ' Archiv fur die Phys.' t. xi., 
 and Wenzel, ' De plenitior. Struct. Cereb.' p. 302. 
 
DISSECTION OF THE BRAIN. 
 
 603 
 
 the middle of the hemisphere, is separated from its fellow by the 
 septum lucid urn. Its roof is formed by the corpus callosum. 
 On the floor, beginning from the front, are seen, the corpus 
 striatum, the tsenia semicircularis, the optic thalamus, the choroid 
 plexus, and the fornix. The anterior horn extends into the 
 frontal lobe, and as it passes forwards it diverges slightly from its 
 fellow of the opposite side. Its roof is formed by the corpus 
 callosum, and it curves round the anterior extremity of the corpus 
 striatum. The posterior horn may be traced into the occipital 
 lobe, where it passes at first backwards and outwards, and then 
 converges towards its fellow. In it are to be noticed an elevation 
 
 FIG. 149. 
 
 1. Corpus callosum. 
 
 2. Lateral ventricle. 
 
 3. Third ventricle. 
 
 4. Corpus striatum. 
 
 5. Thalamus opticus. 
 
 0. Corpus marunril- 
 lare. 
 
 7. Choroid plexus. 
 
 8. Fornix. 
 
 9. Pituitary gland. 
 
 TRANSVERSE VERTICAL SECTION THROUGH THE BBAIN. 
 
 of white substance, the hippocampus minor, also a triangular flat 
 surface external to it, called the pes accessorius or eminentia 
 collateralis* 
 
 The middle horn runs into the middle lobe, descends towards 
 the base of the brain, making a curve, at first backwards and 
 outwards, then downwards and forwards, and lastly inwards : the 
 
 * The posterior horns are not always equally developed in both hemispheres, and 
 sometimes they are absent in one or both. 
 
 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 humm foetus only at an early period. 
 
604 DISSECTION OF THE BKAIN. 
 
 initial letters of which make the memorial word ' bodfi.' By 
 cutting through the substance of the hemisphere, the windings of 
 this horn can be followed ; in it are the hippocampus major, a 
 large rounded white eminence which follows the -curve of the 
 cornu ; the pes hippocampi, the expanded paw-like extremity of 
 the former ; the posterior cms of the fornix, the choroid plexus, 
 and the back of the optic thalamus. 
 
 APPEARANCE If a vertical transverse section were made across 
 
 ON PERPEN- the middle of the brain, the lateral ventricles 
 
 DICULA.R SECTION. wou id appear as represented in fig. 149. Together 
 with the third or middle ventricle, their shape slightly resembles 
 the letter T. 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 temporo-sphenoidal 
 lobe. 
 
 The contents of the lateral ventricles should now be examined 
 more in detail ; also the thin septum (septum lucidum) by which 
 the two lateral ventricles are separated. 
 
 SEPTUM Luci- This is a thin and almost translucent partition 
 
 DUM - which descends vertically in the middle line from 
 
 the under surface of the corpus callosum, and separates the 
 anterior 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 fornix (fig. 148). It is not of equal 
 depth throughout. Its broadest part is in front and corresponds 
 with the knee of the corpus callosum. It becomes narrower 
 behind, tapering to a thin point, where the corpus callosum and 
 the fornix become continuous. The septum consists of two layers, 
 which enclose a space called the fifth ventricle or the ventricle of 
 the septum (fig. 151). Each layer consists of white substance 
 inside, and of grey outside ; the ventricle between them is closed 
 in the adult, and lined with a delicate serous membrane ; but in 
 foetal life it communicates with the third ventricle between the 
 pillars of the fornix.* 
 
 * The development of the septum lucidum commences about the fifth month of 
 
DISSECTION OF THE BEAIN. 
 
 605 
 
 Cut transversely through the corpus callosum and the septum 
 lucidum, and turn forwards the anterior half. In this way the 
 ventricle of the septum will appear, as in fig. 151. 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 nerve-substance 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 com- 
 missure, and lies over the velum interpositum (fig. 148, p. 601). 
 
 1,1. Corpora striata. 
 
 2, 2. Thalami optici. 
 
 3, 3. Anterior crnra 
 
 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, Ventricle of sep- 
 
 tum lucidum. 
 
 DIAGRAM OF THE FORNIX. 
 
 (The arrow is passed through the foramen of Monro.) 
 
 Viewed from its upper surface, it is triangular, with the base 
 behind, as shown in fig. 150. The broad part or body is con- 
 nected with 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 through a mass of grey matter, towards the base of the 
 brain, where, making a sudden bend, they form the corpora 
 mammillaria, from which they may be traced backwards and 
 
 foetal life, and proceeds from before backwards, part passu with the corpus callosum 
 and fornix. 
 
606 DISSECTION OP THE BRAIN. 
 
 upwards, each to the optic thalamus of its own side. As they 
 descend the anterior crura are joined by the peduncles of the 
 pineal body and by the taenia semicircular is. Immediately behind 
 and below the anterior crura is a passage through which the 
 choroid plexuses of opposite sides are continuous with each other. 
 
 FORAMEN OF This aperture is called the foramen of Monro 
 MONBO. (fig. 150). Strictly speaking, it is not a foramen, 
 
 but only a communication between the two lateral and the third 
 ventricles. The posterior crura are continued downwards and 
 outwards from the body of the fornix as thin flat 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.* 
 
 The fornix should now be cut through, and its two portions 
 reflected. On the under surface of the posterior portion are seen 
 fibres, arranged transversely, belonging to the corpus callosum, 
 constituting what is termed the lyra. 
 
 Between the fornix and the upper surface of the cerebellum 
 is the transverse fissure, or fissure of Bichat, through which the 
 pia mater enters the ventricles. The fissure extends from -the 
 middle downwards on each side to the base of the brain, as far as 
 the end of the descending horn. It is of a horse-shoe shape, with 
 the concavity directed forwards. The upper boundary of that 
 part of the transverse fissure which extends into the middle horn 
 is sometimes called the free margin of the hemisphere. 
 
 CORPUS STRIA- This body is so called because, when cut into, 
 TUM. it presents alternate layers of white and grey 
 
 matter.t It is a much larger mass of grey substance than it 
 
 * The fornix and septum lucidum are absent in fish ; they are merely rudimen- 
 tary in reptiles and birds: but all mammalia have them in greater or less perfection, 
 according to the degree of development of the cerebral hemispheres. 
 
 f 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 
 hemisphere. 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. 
 On a transverse section it is triangular, with its base directed outwards. At this part 
 it is divided by two clear linss into three zones. Outside is a grey layer called the 
 claustrum. 
 
DISSECTION OF THE BEAIN. 607 
 
 appears to be ; that which is seen projecting on the floor of the 
 lateral ventricle being only a part of it. The intra-ventricular 
 portion is pear-shaped, broad in front, and when traced backwards 
 is found to taper gradually to a point on the outside of the optic 
 thalamus (p. 605). The under part extra-ventricular portion of 
 the corpus striatum lies embedded in the white substance of the 
 hemisphere, and corresponds with the island of Eeil. 
 
 TJENIA SEMI- This is a narrow semi-transparent band of 
 
 CIRCULARIS. longitudinal white fibres, which lies in the groove 
 
 between the corpus striatum and the optic thalamus (fig. 151). 
 In front, it is connected with the anterior crus of the fornix and 
 descends with it to the corpus mammillare ; behind, it is lost in 
 the white substance of the middle horn of the lateral ventricle. 
 A vein, one or more from the corpus striatum, passes underneath 
 the taenia semi-circularis to join the vena Galeni. 
 
 HIPPOCAMPUS This is an elongated eminence of grey matter, 
 
 MAJQE. covered with white, and is situated in the pos- 
 
 terior 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. 
 
 HIPPOCAMPUS This eminence, smaller than the preceding, is 
 
 MINOR. situated in the posterior horn. It consists of 
 
 white matter externally, and corresponds to the calcarine fissure. 
 Between the hippocampus major and minor, is a triangular smooth 
 surface, called the pes accessorius or eminentia collateralis. This 
 corresponds to the posterior ramus of the fissure of Sylvius. 
 
 VELUM INTER- The velum interpositum, which supports the 
 
 POSITUM AND fornix, should now be examined. This is a layer 
 
 CHOHOID PLEXUS. o f pj a ma ter, which penetrates into the ven- 
 tricles through the transverse fissure, beneath the posterior border 
 of the corpus callosum, as shown in fig. 150. The shape of this 
 vascular membrane is like that of the fornix, and its borders 
 project beneath that body and form the red convoluted fringes 
 called the choroid plexuses. These plexuses consist almost 
 
608 DISSECTION OF THE BRAIN. 
 
 entirely of tortuous ramifications of minute blood-vessels, and 
 are covered with vascular villi. The villi themselves are covered 
 with large spheroidal epithelial cells. In front, the plexuses com- 
 municate with each other through the foramen of Monro ; behind, 
 they descend into the middle horns of the lateral ventricles, and 
 become continuous with the pia mater at the base of the brain. 
 From the under surface of the velum two small vascular processes 
 are prolonged into the third ventricle, forming the choroid plexuses 
 of that cavity. Along the centre of the velum 
 
 VENJK (TALENT 
 
 run two large veins, called vence Galeni, which 
 return the blood from the ventricles into the straight sinus. 
 
 The velum interpositum, with the choroid plexuses, must now 
 be removed to expose the following structures shown in diagram 
 (p. 610): 1. A full view of the optic thalamus. 2. Between the 
 optic thalami is the third ventricle, a deep vertical fissure, situ- 
 ated in the middle line. 3. Behind the fissure is the pineal 
 body, a vascular structure, about the size of a pea. From this 
 body may be traced forwards two slender white cords, called its 
 peduncles one along the inner side of each optic thalamus. 
 4. Passing transversely across the third ventricle are three com- 
 missures anterior, middle, and posterior, connecting the oppo- 
 site sides of the brain. 5. Immediately behind the pineal body 
 are four elevations, two on each side, called the corpora quad- 
 rigemina, or nates and testes. 6. These bodies are connected 
 with the cerebellum by two bands, one on each side, termed the 
 processus a cerebello ad cerebrum. 7. Between these cords 
 extends a thin layer of grey substance, called the value of 
 Vieussens, beneath which lies the fourth ventricle. 
 
 THALAMUS This, called also the posterior cerebral ganglion, 
 
 OPTICUS. is the oval elevation seen on the floor of the 
 
 lateral ventricle, immediately behind the corpus striatum and 
 tsenia semicircularis. The under surface rests upon its correspond- 
 ing crus cerebri, and forms the roof of the middle horn of the 
 lateral ventricle. Though white on the surface, its interior con- 
 sists of alternate layers of white and grey matter. Beneath the 
 posterior part of the thalamus are two small eminences, termed the 
 
DISSECTION OP THE BRAIN. 609 
 
 corpora, geniculata, intemum and externum. These consist of 
 small accumulations of grey matter, beneath the white ; one being 
 situated to the outer, the other to the inner side of the optic tract, 
 fig. 145. A narrow band of white substance connects the external 
 one with the nates, and a similar band connects the internal one 
 with the testes.* 
 
 THIRD YEN- This is the narrow fissure between the optic 
 
 TRICLE. thalami, and reaches down to the base of the brain. 
 
 Its roof is formed by the velum interpositum and fornix ; the floor, 
 which increases in depth in front, is formed by certain parts at the 
 base of the brain, found within the interpeduncular space viz., 
 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. 601. In front, it is bounded by 
 the anterior crura of the fornix, and the anterior commissure; 
 laterally, by the optic thalami and the peduncles of the pineal 
 body ; behind, it communicates with the fourth ventricle through 
 the Her a tertio ad quartum ventriculum, which is a long canal 
 beneath the corpora quadrigemina. 
 
 Passing across the third ventricle are seen three 
 
 COMMISSURES. . . 
 
 commissures, the anterior, middle, and posterior. 
 The middle commissure may be seen by gently separating the 
 
 optic thalami, and is about half an inch in breadth. 
 
 This is composed entirely of grey substance, and 
 in most brains, owing to its softness, is generally torn before it 
 can be examined. f The anterior commissure is a round white 
 
 cord, which lies immediately in front of the 
 
 anterior crura of the fornix, and connects the 
 corpora striata. This commissure may be traced on each side, 
 through the corpora striata, extending backwards far into the 
 
 * These bands are faintly marked in man, but are more apparent in the lower 
 animals. 
 
 f 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 in- 
 stances, according to our observations, is never developed. Wenzel states that it is 
 absent in about one out of seven subjects (' De plenitiori Struct. Cerebri Horn, et 
 Brut.' Tubingen, 1812). 
 
 B R 
 
610 
 
 DISSECTION OF THE BEAUT. 
 
 temporo-sphenoidal lobes. Situated immediately in front of and 
 rather below the pineal body is another thin round 
 
 POSTERIOB. . 
 
 white cord called the posterior commissure. Its 
 fibres pass into the substance of the hemisphere and connect the 
 optic thalami. 
 
 The third ventricle communicates with the lateral ventricles 
 
 Corpus callosum cut through . . 
 
 Ventricle of the septum lucidum . 
 
 Corpus striatum 
 
 Anterior crura of the fornix . . 
 
 Anterior commissure 
 
 Tsenia semicircularis 
 
 Middle commissure 
 
 Thalamns opticus 
 
 Crura of pineal gland 
 
 Posterior commissure , 
 Pineal gland . . . 
 Nates 
 
 Testes 
 
 Valve of Vieussens 
 
 Processus a cersbello ad cerebrum 
 
 through the foramen of Monro, and with the fourth ventricle 
 through the iter a tertio ad quartum ventriculum. 
 
 PINEAL BODY, This vei 7 vascular oval body is situated immedi- 
 
 OE GLANP. ately in front of the corpora quadrigemina (fig. 151). 
 
 It is firmly connected with the under surface of the velum, and is 
 apt to be separated from its normal position when that membrane is 
 
DISSECTION OF THE BRAIN. 611 
 
 reflected. It is about the size of a cherry-stone, and has two white 
 peduncles or crura, which extend forwards, one on the inner side 
 of each optic thalamus, and terminate by joining the anterior 
 crura of the fornix. These crura are connected together behind, 
 and with the front of the posterior commissure. In its interior it 
 contains, besides some viscid fluid, more or less gritty matter, 
 consisting of phosphate and carbonate of lime. 
 
 Although the pineal body is found in all mammalia, birds, 
 and reptiles, in the same typical position, its functions are entirely 
 unknown. 
 
 COEPOBA QUAD- These are four eminences, situated, two on each 
 RIGEMINA. side, behind the pineal body, and are separated 
 
 from each other by a crucial depression. Laterally, they are con- 
 nected with the optic thalami and crura cerebri, and are placed 
 above the iter a tertio ad quartum ventriculum. Though white 
 on the surface, they contain grey matter in the interior for the 
 purpose of giving origin to the optic tract. A more appropriate 
 term for them would be the ' optic lobes,' instead of ' nates and 
 testes,' handed down from the old anatomists. The nates, the 
 more anterior, are rather darker and larger than the testes : and 
 from both proceed outwards two flat white cords, the anterior and 
 posterior brachia. The anterior proceeds to the optic tract, optic 
 thalamus and corpus geniculatum externum, the posterior to the 
 crus cerebri and corpus geniculatum internum.* 
 
 PROCESSUS A CE- By gently drawing back the overlapping cere- 
 RKBEIXO AD CERE- bellum, two broad white cords are seen, which 
 pass backwards, diverging from each other, from 
 the corpora quadrigemina to the cerebellum (fig. 151). These 
 are the processus a cerebello ad cerebrum, or superior peduncles 
 of the cerebellum. They connect the cerebrum and cerebellum, 
 
 * Eminences homologous to the corpora quadrigemina are found in all vertebrate 
 animals ; they are the meso-cephalic lobea ; they always give origin to the optic 
 nerves, and their size bears a direct relation to the power of sight. They are rela- 
 tively 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. 
 
 RR2 
 
612 DISSECTION OF THE BRAIN. 
 
 and rest upon the crura cerebri. 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 Vieussens, is narrow 
 in front, and broad posteriorly, where it is connected with the cen- 
 tral portion of the cerebellum. 
 
 The third ventricle is connected" with the 
 AD QUARTUM VKN- fourth .by a canal large enough to admit a 
 TBICUIUM OK probe, which runs backwards beneath the pos- 
 
 AQUEDUCT OF terior commissure and the corpora quadrigemina 
 
 (p. 601). This passage, together with the third 
 and fourth ventricles, are persistent parts of the central canal 
 which in early foetal life- extended down the middle of the cerebro- 
 spinal axis. It subsequently becomes much encroached upon by 
 the large increase of grey substance, and in its floor are seen the 
 nuclei common to the third and fourth nerves of each side. 
 
 FOURTH VBN- This space is situated between the cerebellum 
 
 TRICLE. and the 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 diagram 
 (p. 601). It appears triangular, and its boundaries are as follows : 
 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 vermiform 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 cerebrum, 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.* 
 
 The anterior wall of the fourth ventricle is lozenge-shaped, 
 and on it are the following objects, which should be separately 
 
 * Tiedemann proposed to call the fourth ventricle the first : because in the foetus, 
 it 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. 
 
DISSECTION OF THE BRAIN. 613 
 
 examined (p. 585): 1. A median groove, the remains of the 
 primitive axis canal ; running parallel to it on each side is a 
 round elevation, the fasciculus teres. 2. From the lower part of 
 the furrow two white cords (the restiform bodies or inferior 
 crura cerebelli) pass off from the medulla oblongata, diverging 
 like the branches of the letter V. and enter the lateral hemi- 
 spheres of the cerebellum. The divergence of these cords, with 
 the median furrow, was called by the old anatomists the calamus 
 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 the restiform bodies ; one slight accumula- 
 tion, external to the fasciculus teres, has received the name of locus 
 cceruleus. 4. On the floor are seen a number of transverse white 
 lines striae medullares emerging from the median groove, 
 some of which form part of the origin of the auditory nerves. 
 c 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 ellipsoidal, with the long axis transverse. When the arachnoid 
 membrane and the pia mater are removed, it is noticed that its 
 surface is darker, and not arranged in convolutions like those of 
 the cerebrum. It consists of a multitude of thin plates, folia, 
 disposed in a series of concentric curves, with the concavity 
 forwards. By a little dissection, it is easy to separate some of 
 the laminae from each other, and to see that the intervening 
 fissures increase in depth from the centre towards the circum- 
 ference. 
 
 The cerebellum consists of two lateral hemispheres united by 
 an intermediate portion, the vermiform process, the upper aspect 
 of which takes the name of the superior vermiform process, the 
 inferior that of the inferior vermiform process. Comparative 
 anatomy proves that this is the fundamental part of the cere- 
 bellum, the lateral masses not being developed in the vertebrate 
 series until after the birds. In man they form by far the largest 
 part of the cerebellum. 
 
 The upper surface is divided from the lower by a deep fissure, 
 
614 DISSECTION OP THE BEAIN. 
 
 named the great horizontal, which extends along the free border 
 of each hemisphere. 
 
 UPPER SUB- The upper surface of the cerebellum slopes on 
 
 FACB - each side, having a ridge along the middle line, 
 
 called the superior vermiform process. This process presents 
 three eminences, an anterior, middle, and posterior, which are 
 named respectively, the lobulus centralis, the monticulus cere- 
 belli, and the commissura simplex. The hemispheres are sepa- 
 rated posteriorly by a deep notch, the incisura cerebelli posterior, 
 which receives the falx cerebelli. On this surface of the cerebel- 
 lum are two lobes, one of which, the quadrate, is situated on its 
 
 FIG. 152. 
 
 pi 
 
 SUPERIOR SURFACE OF THE CEREBELLUM. 
 
 ics. Insisura cerebelli anterior. p i. The posterior inferior lobe. 
 
 ic p. Incisura cerebelli posterior. hf. The great horizontal fissure. 
 
 a s or lq. The anterior superior or quadrate I c. The lobulus centralis. 
 
 lobe. m c. Monticulus cerebelli. 
 
 p s. The posterior superior lobe. c s. Commissura simplex. 
 
 external and anterior aspect, the other, the posterior, is placed 
 along its posterior border. 
 
 UNDER SUB- Q the under surface of the cerebellum, its 
 
 FACE. division into two hemispheres is clearly per- 
 
 ceptible. The deep furrow between them is called the vallecula. 
 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 hemispheres separated from each other. Along the 
 middle line of the vallecula is the inferior vei^miform process. 
 
DISSECTION OP THE BRAIN. 615 
 
 which is the under surface of the fundamental part of the cere- 
 bellum. Traced forwards, this process terminates in the nodule ; 
 traced backwards, it ends 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 different names have been applied (fig. 153). 
 That portion which immediately overlies the side of the vallecula 
 is called the tonsil (amygdala) ; this is connected with the 
 uvula by an indented layer of grey matter, called the furrowed 
 
 FIG. 153. 
 
 INFERIOR SURFACE OF THE CEREBELLUM. 
 
 A. The amygdala. / I. The flocculus. 
 
 Bi. The biventral lobe. n. The nodule \ 
 
 G. The slender lobe. . The uvula I situated in the vallecula. 
 
 H. Th posterior inferior lobe. p. The pyramid ) 
 
 hf. The great horizontal fissure. 
 
 band. At the anterior part of each hemisphere, near the middle 
 line, is a little lobe named the flocculus or subpeduncular lobe. 
 
 From either side of the uvula may be traced a thin valve-like 
 fold of white substance, which proceeds in a semicircular direc- 
 tion to the flocculi. These folds form the posterior medullary 
 velum* To see this satisfactorily, the tonsils must be carefully 
 separated from each other. 
 
 * These are sometimes called the valves of Tarini. 
 
616 DISSECTION OF THE BRAIN. 
 
 In addition to the amygdalae 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 
 posterior inferior lobes. 
 
 PEDUNCLES OF The cerebellum is connected with the cerebro- 
 
 THK CEREBELLUM, spinal axis by three peduncles or crura a superior, 
 middle, and 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 peduncles ; with the 
 cerebrum it is connected by means of the processus e cerebello ad 
 cerebrum ; these are called its superior peduncles. The lateral 
 portions of the pons constitute its middle peduncles. 
 
 INTERNAL To examine the internal structure of the cere- 
 
 STRUCTURK, bellum, a longitudinal section must be made 
 
 through the thickest part of one of its hemispheres. There is 
 then seen in the centre a large nucleus of white substance, from 
 which branches radiate into the grey substance in all directions. 
 Each of these branches corresponds to one of the folia of the 
 cerebellum, and from it other smaller branches proceed and again 
 subdivide. This racemose arrangement 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 arbor 
 vitce. 
 
 CORPUS DEN- In the centre of the white substance of each 
 
 TATUM - hemisphere is a nucleus of grey matter, the corpus 
 
 dentatum., consisting of a zigzag line of yellowish-grey colour, in- 
 complete at its upper and inner part, and enclosing within it some 
 white substance. From its centre white fibres may be traced to 
 the superior cerebellar peduncles and the valve of Vieussens. It 
 is displayed either by a vertical or by a horizontal section. 
 
 Kespecting the function of the cerebellum, the 
 FUNCTIONS. i , j r . 
 
 deductions derived irom comparative anatomy 
 
 and physiological experiments render it probable that it is the 
 co-ordinator of muscular movements e.g.^ in walking, flying, and 
 swimming. 
 
617 
 
 DISSECTION OF THE SPINAL CORD. 
 
 To examine, in situ, the spinal cord covered with its mem- 
 branes, the arches of the vertebrae must be sawn through, and 
 removed. It is then noticed that the cord does not occupy the 
 whole cavity 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 inter- 
 venes, which is filled with a soft reddish-looking fat, with watery 
 cellular tissue, and the ramifications of a plexus of veins. 
 
 FIG. 154. 
 
 1. Anterior external 4lOr.ii 1 '' "' '^liByl \ 3 - Posterior longitudinal 
 
 veins. JK~!iillLM II spinal vein,. 
 
 2. Posterior external (]F' : '''..' ATO^A^KVv.BB 4- Anterior longitudinal 
 
 veins. m^' :: ^MU^^^ii spinal veins. 
 
 * 3 
 DIAGRAM OF THE SPINAL VEINS. (Vertical section.) 
 
 SPINAL SYSTEM The spine is remarkable for the number of large 
 OF VEINS. an d tortuous veins which ramify about it, inside 
 
 and outside the vertebral canal (fig. 154).* There are 1. The 
 posterior external veins which form a tortuous plexus outside 
 the arches and spinous processes of the vertebrae ; they send off 
 branches, which pass through the ligamenta subflava, and end 
 in the plexus inside the vertebral canal. 2. The veins of 
 the bodies of the vertebrce emerge from the backs of the bodies, 
 and empty themselves into 3. the anterior longitudinal 
 spinal veins ; these, two in number, one on each side, are the 
 
 * Vide Breschet, 'Essai sur les Veines du Rachis,' 4to. ; ' Traite Anatomique sur 
 le Systeme Veineux, fol. avec planches,' 1829; also Cloquet, 'Traite d'Anatomie 
 descriptive.' 
 
618 
 
 DISSECTION OF THE SPINAL CORD. 
 
 large tortuous veins which extend down the spinal canal, behind 
 the bodies of the vertebrae. 4. The posterior longitudinal 
 spinal veins, like the anterior, run along the whole length 
 of the spinal canal. They form a tortuous venous plexus, 
 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 lie within the dura mater. 
 They form a fine plexiform arrangement of veins over both sur- 
 faces of the cord, and can with difficulty be injected from the 
 other spinal veins. This complicated system of veins dis- 
 charges itself through the intervertebral foramina in the several 
 
 FIG. 155. 
 
 1. Anterior external 
 
 veins. 
 
 2. Posterior external 
 
 veins. 
 
 3. Posterior longitudinal 
 
 spinal veins. 
 
 4. Anterior longitudinal 
 
 spinal veins. 
 
 5. Internal veins of the 
 
 body of the vertebra. 
 
 6. Lateral veins. 
 
 DIAGRAM OF THE SPINAL VEINS. (Transverse section.) 
 
 regions of the spine, as follows : In the cervical, into the vertebral 
 veins ; in the dorsal, into the intercostal 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. 
 
 The membranes of the spinal cord, though continuous with 
 those of the brain, differ from them in certain respects, 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, being separated from them by fat, loose 
 areolar tissue, and the plexus of veins described above. Moreover, 
 such adhesion would impede the free movement of the vertebrae 
 
 DURA MATER. 
 
DISSECTION OP THE SPINAL CORD. 619 
 
 upon each other. It is attached firmly above to the margin of the 
 foramen magnum, and may be traced downwards as a sheath as far 
 as the second bone of the sacrum, from which it is prolonged as a 
 cord to the coccyx, where it becomes continuous with the peri- 
 osteum. It forms a complete canal or bag, which surrounds loosely 
 the spinal cord, and sends off a prolongation over the trunk of 
 each spinal nerve. 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. 
 
 ARACHNOID The arachnoid membrane of the cord is a con- 
 
 MEMBHANE. tinuation from that of the brain, and, like it, 
 
 consists of a visceral layer, which surrounds the cord, and a 
 parietal, which lines the inner surface of the dura mater. The 
 visceral layer is not in immediate contact with the pia mater 
 beneath it, but is separated from it by a transparent watery fluid 
 contained in the meshes of the subarachnoid tissue (p. 579.) 
 
 CEREBRO- This cerebro-spinal fluid cannot be demon- 
 
 SPINAL FLUID. strated unless the cord be examined very soon after 
 death, and before the removal of the brain.* The nerves proceed- 
 
 * 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, 'Kecherches 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. It can be made to flow from the brain into the cord, or vice versd. 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 Mith 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 
 
620 DISSECTION OF THE SPINAL CORD. 
 
 ing from the cord are loosely surrounded by a sheath of the arach*? 
 noid ; 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 
 very different in structure from that of the brain, since it does 
 not constitute a membrane 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. It sends down thin folds 
 into the anterior and posterior median ns"sures of the cord, and is 
 prolonged upon the spinal nerves, forming their investing mem- 
 brane or ' neurilemma.' 
 
 Over the anterior median fissure may be traced a well-marked 
 fibrous band, formed by the pia mater, which has been named the 
 linea splendens. 
 
 Below the level of the second lumbar vertebra, the pia mater 
 is continued as a slender filament, called the filum terminate, or 
 central ligament, which runs down in the middle of the bundle 
 of nerves into which the spinal cord breaks up. About the level 
 of the third sacral vertebra it becomes continuous with the dura 
 mater of the cord, and is then prolonged as far as the base of 
 the coccyx. The spine of the third sacral vertebra marks the level 
 to which the cerebro-spinal fluid descends in the vertebral canal. 
 
 LIQAMENTUM From each side of the cord along its whole 
 
 DENTICULATUM. length there runs a fibrous band, lig ' amentum 
 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. 156). There are from eighteen to twenty-two of them on 
 each side, and they lie between the anterior and posterior roots of 
 the spinal nerves. The first process passes between the vertebral 
 artery and the hypoglossal nerve ; the last is found at the ter- 
 mination of the cord. It is composed of fibrous tissue, and is 
 
 nervous axis generally. See some remarks very much to the point, by Sir George 
 Burrows, ' On Diseases of the Cerebral Circulation,' p. 50, 1846. 
 
DISSECTION OP THE SPINAL COED. 
 
 621 
 
 SPINAL CORD. 
 
 FIG. 156. 
 
 DIAGRAM OF THE LIGAMENTUM 
 DENTICTTLATUM. 
 
 enticuiatum. 
 
 covered with nucleated cells continuous with the arachnoid mem- 
 brane.* 
 
 The spinal cord is that 
 part of the cerebro-spinal 
 axis contained in the vertebral canal. 
 It is the continuation of the medulla 
 oblongata, and extends from the fora- 
 men magnum down to the upper border 
 of the second lumbar vertebra, where 
 it terminates in a conical point, conus 
 medullaris, after having given off the 
 large bundle of nerves termed cauda 
 
 equina, for the Supply 
 CAUDA EQUINA. * rr 
 
 oi the lower limbs, r rom 
 
 the conus medullaris there is continued 
 downwards a slender cord, the/Hum terminale, which passes within 
 the sheath to the coccyx. f The length of the cord is from fifteen 
 to eighteen inches, and its general form is ' cylindrical, slightly 
 flattened in front and behind. It is not of uniform dimensions 
 throughout. It presents a considerable enlargement in the lower 
 part of the cervical region ; another in' the lower part of the 
 dorsal, from which proceed the large nerves to the upper and 
 lower limbs, respectively. The upper or cervical enlargement, 
 which is the larger, extends from the third cervical to the 
 first dorsal vertebra ; the lower, or lumbar, is situated opposite 
 to the last dorsal vertebra. J 
 
 The cord is divided into two symmetrical halves 
 by a median longitudinal fissure in front and 
 behind (fig. 157). The anterior fissure is the more distinct, and 
 
 Dura mater . 
 2, 2. 
 
 FISSURES. 
 
 * Vide Axel, Key, and Eetzius; Max Schultze's 'Archives,' 1873. 
 
 t 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 from the cord, in accordance with the more 
 active development of the lower limbs. See Tiedemann, ' Anatomie und Bildungs- 
 geschichte des Gehirns im Foetus des Menschen,' &c.; Nuremberg, 1816. 
 
 J In very early foetal life these enlargements do not exist, and only make their 
 appearance with the development of the extremities. 
 
622 
 
 DISSECTION OP THE SPINAL COED. 
 
 penetrates about one-third of the substance of the cord. It con- 
 tains a fold of pia mater, with many blood-vessels for the supply 
 of its interior. At the bottom of this fissure is a transverse 
 layer of white substance, named the anterior white commissure, 
 connecting the two anterior halves of the cord. The posterior 
 fissure is so much less apparent than the anterior, that some 
 anatomists deny its existence ; but by careful preparation it can 
 be demonstrated, although it does not contain a fold of pia mater. 
 Indeed, it can be traced to a greater depth than the anterior, 
 and reaches down as far as the posterior grey commissure 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 
 
 FIG. 157. 
 
 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 
 
 spiual nerve. 
 
 7. Anterior branch of 
 
 spinal nerve. 
 
 COLUMNS. 
 
 DIAGRAM OF A THANSVERSE SECTION THROUGH THE SPINAL CORD 
 AND ITS MEMBRANES. 
 
 are the anterior and posterior lateral fissures (fig. 157). 
 The posterior leads down to the posterior horn of the grey 
 matter in the interior of the cord; the anterior is simply 
 the groove from which the anterior roots emerge. By these 
 lateral fissures each half of the cord is divided into 
 three longitudinal columns an anterior, a pos- 
 terior, and a lateral. On each side of the posterior median 
 fissure is a slender column, called the posterior median column, 
 which is separated from the posterior column by a shallow furrow. 
 INTERNAL A transverse section through the cord (fig. 157) 
 
 STRUCTUBE. shows that, externally, it is composed of white 
 
 nerve-substance, and that its interior contains grey matter, 
 arranged in the form of two crescents, with their backs to each 
 
DISSECTION OF THE SPINAL CORD. 628 
 
 other. Each crescent is placed in the corresponding half of the 
 cord, and is connected with its fellow across the centre by a 
 portion called the posterior or grey commissure.* The posterior 
 horns 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 attachment of the anterior roots of the nerves, 
 but do not reach the surface. Separating the grey commissure 
 from the anterior median fissure is the anterior or white com- 
 missure. 
 
 On making transverse sections through different regions of the 
 spinal cord the grey substance is seen to vary in shape : in the 
 cervical region the anterior cornua are thick and short, the pos- 
 terior are long and slender ; in the dorsal, the anterior and 
 posterior cornua are both thin ; in the lumbar, the anterior and 
 posterior cornua are large and broad ; in the lower part of the cord 
 the grey matter is arranged in a central mass. Eunning along the 
 CENTRAL centre of the cord in its whole length is a minute 
 
 CANAL, canal, just visible to the naked eye. It is lined 
 
 with cylindrical ciliated epithelium, and opens superiorly into the 
 fourth ventricle. The central canal is interesting, as- it is the 
 remains of the cavity formed by the spinal cord at the earliest 
 period of its development.-f- 
 
 Thirty-one pairs of nerves arise from the spinal 
 
 SPINAL NERVES. . , . , . . . , 
 
 cord, namely, eight in the cervical region, twelve 
 in the dorsal, five in the lumbar, five in the sacral, and one in the 
 coccygeal. Each nerve is formed by the junction of two series of 
 roots, one from the front, the other from the back of the cord. 
 Two BOOTS, Sir Charles Bell first discovered the fact, that 
 
 SENSITIVE AND the anterior roots consist exclusively of motor 
 MOTOR. filaments, and the posterior exclusively of sensory. 
 
 * The different appearances of the arrangement of the grey matter in the cord 
 have been accurately described and figured by Rolando, 'Eicherche Anatomiche sulla 
 Struttura del Midollo Spinale, con Figure, art. tratto dal Dizionario Periodico di Me- 
 diana;' Torino, 1824, 8vo. p. 55. 
 
 f The central canal is well seen in fishes, birds, and reptiles. 
 
624 DISSECTION or THE SPINAL CORD. 
 
 All converge in the corresponding invertebral foramen to form a 
 single nerve, composed of motor and sensory filaments. 
 
 The filaments of the posterior or sensory roots are thicker and 
 more numerous than the anterior. They proceed from the pos- 
 terior lateral fissure, and previous to their union with the anterior 
 roots are collected together and pass through a ganglion. 
 The ganglion is of an oval form, and lies in the intervertebral 
 foramen. The fibres composing these roots enter the cord, and 
 may be traced to the posterior cornu, through which they pass in 
 various directions. The anterior roots arise from the fissure 
 between the anterior and lateral columns of the cord. The fibres 
 of the anterior root may be traced through the antero-lateral fissure 
 into the anterior cornu.* , 
 
 The compound nerve formed by the junction of the two roots 
 (after the formation of the ganglion of the posterior) divides, out- 
 side the intervertebral foramen, into an anterior and a posterior 
 branch. See diagram, p. 622. 
 
 VAHIATION IN The direction and length of the roots of the 
 
 THE LENGTH OF nerves vary in the different regions of the spine, 
 THE ROOTS. owing to the respective parts of the cord from 
 
 which they arise not being opposite to the foramina through which 
 the nerves leave the spinal canal. In the upper part of the cer- 
 vical 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. Lower down, however, the obliquity and 
 length of the roots gradually increase, so that the roots of the 
 lower dorsal nerves are at least a vertebra higher than the fora- 
 mina through which they emerge. Again, since the cord itself 
 terminates at the upper border of the second lumbar vertebra, 
 
 * The researches of Blandin, 'Anat. descript.,' t. ii., p. 648, 1838, have led him to 
 establish the following relation between the respective size of the anterior and 
 posterior roots of the nerves in the several regions of the spine : 
 
 The posterior roots are to the anterior in the cervical region 
 ,, ,, dorsal 
 
 lumbar and sacral 
 
 1 
 
 This relation quite accords with the greater delicacy of the sense of touch in the 
 upper extremity. 
 
DISSECTION OF THE SPINAL COED. 625 
 
 the lumbar and sacral nerves must descend from it almost per- 
 pendicularly through the lower part of the spinal canal. To 
 
 CAUDA this bundle of nerves the old anatomists have 
 
 EQUINA. given the name of cauda equina, from its resem- 
 
 blance to a horse's tail. 
 
 To sum up briefly, it appears that the spinal cord consists of 
 two 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 white nerve-fibres an anterior, a lateral, and a 
 posterior 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 constitutes the posterior 
 commissure. 
 
 BLOOD-VESSELS The cord is supplied with blood by 1. The 
 OF THE COED. anterior spinal artery, which commences at the 
 medulla oblongata by a branch from the vertebral of each side, 
 and then runs down the middle of the front of the cord. Other 
 branches are derived from the vertebral, ascending cervical, inter- 
 costal, and lumbar arteries, which pass through the intervertebral 
 foramina, and assist in keeping up the size of this anterior artery. 
 2. The posterior spinal arteries, which proceed also from the 
 vertebral, intercostal, and lumbar arteries, and ramify somewhat 
 irregularly on the back of the cord. 
 
 On the posterior part of the bodies of the vertebrae, 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 spinal cord performs, at least, three func- 
 
 THE SPINAL CORD, tions: 1. It is the general conductor of impres- 
 sions to, and from, the brain. 2. It transfers impressions. 3, It 
 is a centre of reflex action. Sensory impressions are conducted by 
 
 8 S 
 
626 DISSECTION OF THE SPINAL CORD. 
 
 the posterior roots of the spinal nerves to the cord, and are thence 
 transmitted to the brain through the posterior columns and the 
 grey matter of the cord. These impressions do not run up on the 
 same side, for the fibres, immediately on entering the grey matter, 
 cross over to the opposite side to reach the brain ; so that if the 
 posterior column of the right side be divided, the left leg, and not 
 the right, would be deprived of sensation. Motor impulses are 
 conveyed along the antero-lateral columns and the grey matter in 
 them, and carry the commands of the will from the brain to the 
 muscles. The crossing of the motor fibres takes place in the 
 medulla oblongata, at the decussation of the anterior pyramids, so 
 that they run in the corresponding half of the cord as far as their 
 point of decussation. Division, therefore, of one half of the cord 
 below this point, causes paralysis of motion on the same side of 
 the body. .The: cord is, .moreover, concerned in the conduction 
 of impressions to and from the vaso-rtwtor centre of the medulla 
 oblongata, which determines the varying conditions of the blood- 
 vessels. The cord also transfers impressions ; this is more manifest 
 in disease than in health ; a well-marked example of transference is, 
 that pain is felt at .the -knee in cases of disease of the hip-joint. 
 The spinal cord has probably no power of originating impressions, 
 in other words, it is not automatic. 
 MINUTE STRUC- These are among the most complicated parts of 
 
 TUBE OF THE ME- ^ cen t ra l nervous system. They contain white 
 DCJI/LA OBLONGATA , . , . , m i , ., 
 
 T, and grey nerve-matter intermixed. I he white 
 
 AND .TONS & J 
 
 VAEOLH. matter consists, in part, of the continuation up- 
 
 wards of the longitudinal fibres of the cord; in part, of horizontal 
 
 fibres. 
 
 ANTERIOR The anterior columns of the cord (fig. 158), 
 
 PYRAMIDS. having reached the lower part of the medulla 
 
 oblongata, are not continued straight through it, but diverge 
 from each other, being pushed aside by the deep fibres of the 
 lateral columns, which here cross each other, and form the de- 
 cussation of the anterior pyramids. In their further progress the 
 fibres of the anterior columns are arranged thus : some of them run 
 up, and form the outer portion of their own pyramid : some ascend 
 
DISSECTION OP THE SPINAL COED. 
 
 627 
 
 beneath the olive to join the restiform body; a third set pass 
 upwards and, after embracing the olive, reunite, to form a single 
 bundle ; this, joined by fibres (olivary fasciculus) from the olive 
 ascends under the name of the fillet of Reil, over the superior crus 
 of the cerebellum to the corpora quadrigemina and the cerebral 
 hemispheres (fig. 159). 
 
 The lateral columns on reaching the medulla oblongata are 
 disposed off in three ways, as follows : some of its fibres come 
 forward between the diverging anterior columns, decussate in the 
 middle line and form part of the pyramid of the opposite side ; 
 
 Fio. 158. 
 
 1. Anterior column. 
 
 2. Lateral column. 
 
 3. Posterior column. 
 
 4. Posterior median column 
 
 of the spinal cord. 
 
 5. Anterior pyramid. 
 
 6. Eestiform body. 
 
 7. Posterior pyramid. 
 
 8. Fasciculus teres. 
 
 9. Inferior crus of the cere- 
 
 bellum. 
 
 10. To the corpora quadri- 
 gemina. 
 
 11. Crus cerebri. 
 
 DIAGRAM OF THE COURSE OF THE FIBRES THROUGH THE MEDULLA OBLONGATA. 
 
 others ascend with the restiform body (or tract) into the cere- 
 bellum ; a third set ascends along the floor of the fourth ventricle 
 (concealed by its superficial grey matter) as the fasciculus teres, 
 and is continued along the upper part of the crus cerebri into 
 the cerebrum. 
 
 RESTIFORM The posterior columns ascend (under the name 
 
 BODY, of the restiform bodies), at the back of the medulla, 
 
 diverge from each other, and are continued partly into the cere- 
 bellum, forming its inferior crura, and partly as the fasciculi 
 teretes along the floor of the fourth ventricle into the cerebrum. 
 
 s s 2 
 
DISSECTION OF THE SPINAL COED. 
 
 POSTEEIOK These are the continuations upwards of the 
 
 PYRAMIDS. posterior median columns of the cord ; and, like the 
 
 restifonn body, each divides into two fasciculi, one of which ascends 
 and helps to form the inferior crus of the cerebellum, the other 
 runs up with the fasciculus teres. 
 
 HORIZONTAL The horizontal fibres in the medulla oblongata 
 
 FIBRES, and the pons were first accurately described by 
 
 Stilling and subsequently by Kolando. Some of them form a 
 septum, and divide the medulla oblongata and pons into sym- 
 metrical halves ; others, arising apparently from the septum, 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 arciform fibres of Rolando 
 (p. 584.) Stilling * and K611iker,f who have studied the subject, 
 are of opinion that they originate in the restiform bodies, and 
 thence arch forwards some on the surface, others through the 
 substance of the medulla, and that they eventually join the fibres 
 of the septum, 
 
 INTERNAL The pons consists of transverse and longitudinal 
 
 STEUCTURE OF THE white fibres, with a considerable quantity of grey 
 PONS VAROLH. matter in its interior. The superficial layer of 
 fibres is obviously transverse, and connects the two hemispheres of 
 the cerebellum. After removing the first layer, we expose the 
 longitudinal fibres of the pyramids in their course to the crura 
 cerebri ; these longitudinal fibres, however, are intersected by 
 the deep transverse fibres of the pons, which, like the superficial, 
 are continued into the cerebellum. The deepest layer of the pons 
 consists entirely of longitudinal fibres, derived partly from the 
 lateral columns, partly from the restiform bodies of the medulla. 
 CRURA These are composed of longitudinal fibres, de- 
 
 CEREBBI. rived from the pyramids, from part of the lateral 
 
 * 'Ueber die Medulla Oblongata,' Erlangen, 1843. 
 f 'Mikroskopische Anatomic,' p. 454. 
 
DISSECTION OP THE SPINAL COED. 
 
 629 
 
 and restiform columns of the cord, and from the grey matter 
 in the pons Varolii. If one of the crura be divided longitudinally, 
 there is found in the middle of it a layer of dark-coloured nerve- 
 substance, called locus niger, which separates the crus into an 
 upper and lower stratum of fibres. The lower stratum is tough 
 and coarse, and consists of the continuation of the fibres pro- 
 
 FIG. 159. 
 
 Corpus striatum. 
 
 Thalamus opticus. 
 
 Crus cerebri. 
 
 Locus niger. 
 
 Pons Varolii, denoted by 
 
 transverse lines. 
 Pyramid. 
 Olive. 
 
 Anterior columns. 
 Lateral columns. 
 Posterior columns. 
 Corpora quadrigemina. 
 Fillet of Eeil. 
 Superior crus of the 
 
 cerebellum. 
 Cerebellum. 
 
 DIAGRAM OF THE COURSE OF THE FIBRES THROUGH THE MEDULLA AND POKS. 
 
 ceeding from the pyramid and the pons. The upper stratum is 
 much softer and finer in texture, and has received the name of 
 tegmentum: it is composed of the fibres proceeding from the 
 lateral and restiform columns ; also from the superior crus of 
 the cerebellum. Tracing the fibres of the crus cerebri into the 
 
630 DISSECTION OF THE SPINAL CORD. 
 
 cerebral hemisphere, we find that its lower fibres ascend chiefly 
 through the corpora striata, its upper fibres through the thalami 
 optici. In passing through these ganglia, the crus receives a 
 large addition to its fibres: these branch out widely towards 
 all parts of the hemisphere, in order to reach the cortical sub- 
 stance on the surface. 
 
631 
 
 DISSECTION OF THE EYE. 
 
 SINCE the eye in the human subject cannot be obtained suf- 
 ficiently fresh for anatomical purposes, the student should examine 
 the eye of the sheep, bullock, or pig. The conjunctiva membrana 
 should be removed, together with the loose connective tissue which 
 unites it to the sclerotica. 
 
 CONJUNCTIVA ^ e conjunctiva is the mucous membrane which 
 
 covers the ocular surface of the eyelids and the 
 anterior part of the globe, and is lined with columnar epithelium. 
 It is loosely attached to the sclerotic coat, so as not to impede 
 the movements of the globe. The palpebral portion of it is 
 very vascular, and provided with fine papillae abundantly sup- 
 plied with nerves.* It is continued into the Meibomian glands, 
 the puncta lachrymalia, and the ducts of the lachrymal gland. 
 The sclerotic portion is thinner and has no papillae. It is trans- 
 parent and nearly colourless, except when inflamed ; it then 
 becomes intensely vascular, and of a bright" 'scarlet colour. An 
 abundant supply of nerves is distributed to the membrane ; their 
 arrangement is stated to be the same as that of the skin, but many 
 of them have been described as terminating in end-bulbs. 
 
 The corneal conjunctiva is composed chiefly of epithelium, 
 arranged in layers. This portion of the conjunctiva cannot be 
 separated 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 often involve the cornea 
 and render its texture thick and opaque.f Blood-vessels ramify 
 
 * These papillae were first described by Eble, .,' Ueber den Bau und di&Krank- 
 heiten der Bindehaut des Auges,' 
 
 f The facts of comparative anatomy confirm this vievr. In the serpent tribe, 
 
632 DISSECTION OF THE EYE. 
 
 round the margin of the cornea, forming a network arranged in 
 loops. Lymphatics exist abundantly in the palpebral and sclerotic 
 conjunctiva, and communicate, after becoming much reduced in 
 size, with the irregular cell-spaces of the cornea. 
 
 The human eye is nearly spherical, the antero-posterior and 
 vertical diameters being equal, the transverse exceeding these by 
 less than half a line. The convexity of the cornea 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 He- The globe is composed of three coats, arranged 
 MOUHS OF THE one within the other, which enclose certain 
 EYE - transparent structures. The external coat, con- 
 
 sisting of the sclerotic and cornea, is fibrous, thick, and strong. 
 The second coat, consisting of the choroid, the iris, and the ciliary 
 processes,is composed of blood- vessels, muscular tissue, and pigment- 
 cell?, 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 the waves of light. The bulk of the interior is filled 
 with a transparent humour, called the vitreous body. Embedded 
 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 moveable curtain, called the iris, to 
 regulate the amount of .'light .*which shall be admitted through a 
 central aperture, the pupil, to the fundus of the eye. The space 
 in which the iris is suspended is filled with a fluid, termed the 
 aqueous humour. 
 
 SCLEEOTIC The sclerotic is the tough protecting coat of the 
 
 COAT. eye, and consists of white fibres interlacing in all 
 
 directions.* It covers about five-sixths of the globe, the remaining 
 
 which annually shed the. 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. 
 
 * The sclerotic coat of the eye in fishes is of extraordinary thickness and density ; 
 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 paiticularly in the fossil ichthyosauri 
 and plesiosauri. 
 
DISSECTION OF THE EYE. 633 
 
 one-sixth being completed by the cornea. The thickest part of 
 
 the sclerotic coat is at the back of the globe (fig. 161):; the thinnest 
 
 is a short distance behind the cornea.* The back of the sclerotic 
 
 is perforated by the optic nerve, which enters it about one-tenth of 
 
 an inch on the nasal side of the axis 5 1G 160 
 
 of vision. The optic nerve at its 
 
 entrance into the sclerotic is mudh 
 
 constricted, and instead of passing 
 
 through a single aperture in this 
 
 coat, enters it through a porous 
 
 network of fibrous tissue, called the 
 
 lamina cribrosa.] The sheath of 
 
 the optic nerve becomes continuous 
 
 with the sclerotic where it perforates 
 
 this coat. Around the optic nerve 
 
 the sclerotic is perforated by the 
 
 ciliary arteries, veins, and nerves, INSEETION OF THK EECTI MUSCT,ES WITH 
 
 ~ ,, - ,, , . , ANTERIOR CILIARY ARTERIES. 
 
 tor the supply 01 tne choroid and 
 
 iris. About a quarter of an inch from the cornea the sclerotic 
 receives the insertion of the recti muscles ; here also it transmits 
 the anterior ciliary arteries, which run forward along the tendons 
 of these muscles, and form a vascular ring around the margin of 
 the cornea (fig. 160). 
 
 The sclerotic is ^composed of connective tissue arranged in 
 bundles, which run, some longitudinally, some transversely. The 
 longitudinal fibres are the most -external and abundant. Under 
 the microscope numerous connective-tissue corpuscles may be seen 
 filling cell-spaces, similar to those found in the cornea, but not so 
 abundant, and containing pigment-granules. Between these may 
 be demonstrated fine elastic fibres. The inner surface of the 
 sclerotic is coated with a thin layer of connective tissue, lamina 
 fusca, in which are found some pigment-cells. 
 
 To examine the cornea, it should be removed with the sclerotic 
 
 * The greatest thickness posteriorly is about the ^gth ^ an inch; its least thick- 
 ness in front is about ^th of an inch. 
 
 t In the centre of the lamina cribrosa is an opening larger than the rest, which 
 transmits the arteria centralis retinse. 
 
634 
 
 DISSECTION OF THE EYE. 
 
 coat. This should be done under water, by making a circular cut 
 with scissors, about a quarter of an inch from the margin of the 
 cornea. With a little care it will be easy to remove the outer coat 
 of the eye without injuring the dark choroid coat, the ciliary 
 muscle, or the iris. In the loose brown-coloured connective tissue 
 between the sclerotic and the choroid are the ciliary nerves passing 
 forwards to the iris; their white colour makes them very con- 
 spicuous on the dark ground. 
 
 The cornea is the brilliant translucent coat which 
 forms about the anterior one-sixth of the globe. It 
 
 FIG. 161. 
 
 Hyaloid membrane 
 
 Retina (dotted line) 
 
 Choroid coat (black 
 
 line 
 
 Sclerotic coat . 
 
 Cornea. 
 
 Iris. 
 
 Ciliary processes. 
 
 Canal of Schlemm 
 
 or Fontana. 
 Ciliary ligament. 
 
 1. Anterior chamber filled with aqueous humour. 
 
 2. Posterior chamber. 3. Canal of Petit. 
 
 DIAGRAM OF A VERTICAL SECTION OF THE EYE. 
 
 is nearly circular in shape, its diameter being nearly half an inch, 
 and its thickness about -^ of an inch. The curve of the cornea 
 forms part of a smaller circle than that of the sclerotic, so that it 
 projects further forwards, varying in this respect in different eyes, 
 and at different ages of life. It is firmly connected at its margin 
 to the sclerotic, with the fibres of which it is continuous. The 
 margin of the sclerotic is bevelled on the inside ; that of the cornea 
 on the outside, so that the former overlaps the latter (fig. 161). 
 
DISSECTION OP THE EYE. 635 
 
 The cornea consists of five layers, which are not 
 all composed of the same kind of tissue. The 
 most superficial layer is the conjunctival. This consists of several 
 strata of epithelial cells ; the deeper ones, the more numerous, are 
 columnar and placed vertically, the superficial ones are flattened 
 scaly epithelium cells, with well-marked nuclei. The second 
 layer is about the TSTRT of an inch thick, and consists of a perfectly 
 structureless lamina, which, when peeled off, has a remarkable 
 tendency to curl. Boiling, or the action of acids, does not render 
 it opaque, like the other layers of the cornea. The third layer 
 (cornea proper} consists of translucent, connective tissue, upon 
 which the thickness and strength of the cornea mainly depend. 
 The fibres are arranged in layers, about sixty in number. Between 
 the laminae are irregularly branched spaces, called the cell-spaces of 
 the cornea. In these spaces are lodged the corneal corpuscles, 
 with outstanding processes, which communicate freely with each 
 other, and correspond in shape to the spaces within which they lie. 
 In inflammation of the cornea these corpuscles undergo consider- 
 able changes.* The fourth layer is translucent, elastic and 
 brittle, and may be easily separated from the preceding laminse. 
 Like the second layer, it is unaffected by boiling or by the action 
 of acids or alkalies, but is somewhat thinner, being from 20 ' 00 to 
 -3 Vo~ of an inch in thickness. It is termed the membrane 
 of Descemet. In the sclerotic coat, close to its junction with the 
 cornea, is-situated-'a smalb aval canal, lined with epithelium, 
 termed the sinus circularis iridis, or canal of Schlemm (fig. 
 161). It is probably a venous sinus, for it can always be 
 injected from the arteries. The Jifth layer consists of a single 
 layer of polygonal epithelial cells-, resembling those which line 
 serous membranes.f In its healthy state the cornea contains no 
 
 * If fluid be injected very gently into the cornea proper, there may be demon- 
 strated a system of canals, called Kecklinghausen 's canals, which are the communica- 
 tions between the corneal corpuscles ; but if the fluid be injected more forcibly, it 
 passes in the course of the fibres composing the various laminae of the cornea, which 
 gives the appearance of a number of varicose and enlarged tubes crossing each other 
 at right angles: these are termed Bowman's corneal tubes. 
 
 f For a detailed description of the structure see Todd and Bowman, 'Physio- 
 logical Anatomy.' 
 
636 DISSECTION OP THE EYE. 
 
 blood-vessels, except at its circumference, where they form loops. 
 Its nerves, which are numerous, forty to forty-five in number, may 
 be traced forwards in the transparent tissue as a fine plexus ; this 
 gives off minute fasciculi, which ramify beneath the epithelium, 
 constituting the sub-epithelial plexus. From this very minute 
 filaments run between the epithelium cells, forming the intra- 
 epithelial plexus. 
 
 After the removal of the sclerotic and cornea, 
 we expose the choroid coat,* and its continuation 
 formerly known as the ciliary processes. In connection also with 
 this tunic is a white ring, the ciliary muscle. 
 
 The choroid is the soft and flocculent tunic of the eye, recog- 
 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 passes beneath the ciliary muscle with 
 which it is connected, and then extends forwards, terminating 
 in a series of plaited folds, called the ciliary processes. It is 
 connected with the sclerotic by delicate connective tissue, the 
 lamina fusca, through which the ciliary vessels and nerves pass 
 forwards. 
 
 CILIARY PRO- The ciliary processes are the folds formed by 
 
 CESSES. the anterior part of the choroid, and may be best 
 
 seen when the globe has been divided by a vertical section into an 
 anterior and a posterior half, the ^vitreous humour being left un- 
 disturbed. They are black, and consist of from sixty to seventy 
 radiating folds, arranged in a circle about three lines broad. These 
 processes consist of longer and shorter folds, the former being the 
 more numerous. The longer fold is about a line in length ; the 
 smaller about half a line. One of the longer ones is seen in 
 the diagram, p. 634. The processes fit into corresponding folds 
 of the suspensory ligament of the lens, and their free ends 
 project for a short distance into the posterior chamber. The 
 vascular supply of the ciliary processes is most abundant, and 
 resembles in the main that of the choroid. The ^arteries come 
 
 * So called because its outer flocculent surface somewhat resembles the choriou, 
 or external investment of the ovum. 
 
DISSECTION OF THE EYE. .637 
 
 chiefly from the anterior ciliary, and from the front vessels of the 
 choroid ; and after breaking up into a fine plexus, they form loops 
 which arch backwards to end in the smaller veins. Their dark 
 colour arises from pigmented cells, which disappear, however, at 
 the free ends of the processes. 
 
 Under the microscope the choroid is seen to consist of two layers, 
 both composed of blood-vessels held together by fine connective 
 tissue, in which are found large ramified pigment-cells. The outer 
 layer consists of the larger branches of the blood-vessels ; the 
 
 Fm. 162. 
 
 ^t 
 
 Sclerotic coat . . 
 
 Veins of the choroid. JffiSI BS^ Ciliary body. 
 
 ___ Iris. 
 
 Ciliary nerves . 
 
 Veins of the choroid . 
 
 SCLEROTIC COAT BEHOVED TO SHOW THE CHOEOID, CILIARY LIGAMENT, AND NERVES. 
 
 arteries (short ciliary) being chiefly on the inner, the veins on the 
 outer, surface. The veins are arranged with, great regularity in 
 drooping branches (vasa vorticosa\. like a weeping-willow (fig. 
 162), and converge to four or five nearly equidistant trunks, which, 
 after running backwards for a short distance, perforate the sclerotic 
 not far from the entrance of the optic nerve, and empty themselves 
 into the ophthalmic vein. The inner layer is formed by the 
 capillaries of the ciliary arteries, and is called, after the Dutch 
 anatomist Ruysch, ' tunica Ruysckiana? It consists of the most 
 delicate vascular network found in any tissue y and extends forwards 
 to the ciliary processes, with the capillaries of which it freely 
 communicates. 
 
638 DISSECTION OP THE EYE. 
 
 Between the choroid membrane and the lamina fusca of the 
 sclerotic is a layer of connective tissue, the lamina supra cho- 
 roidea, which serves to connect the two tunics. 
 
 CILIARY This muscle consists of unstriped fibres, and 
 
 MUSCLE. arises by a thin tendon from the sclerotic close to 
 
 its junction with the cornea. Thence its fibres radiate backwards, 
 and are lost in the choroid behind the ciliary processes. Some 
 of these fibres form a circular muscle around the outer circum- 
 ference of the iris, constituting the circular -ciliary muscle, which 
 was formerly described as the ciliary ligament. Its action is to 
 accommodate the eye to objects at various distances, by rendering 
 the lens more or less convex.* 
 
 The iris is the contractile curtain suspended in 
 the clear fluid, which fills the space between the 
 cornea and the lens. The iris divides this space into two un- 
 equal parts, called the anterior and posterior chambers (fig. 161); 
 these 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 immoveably 
 connected with the ciliary muscle, 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 taking the 
 name of uvea from its grape-like colour. Pigmented cells are 
 also found in the substance of the iris. 
 
 When the iris is laid under water, and viewed with a low mag- 
 nifying power, it is seen to be composed of fine fibres converging 
 from all sides towards the pupil ; many of them unite and form 
 
 * Sir Philip Crampton has noticed that this muscle is well developed in birds. 
 In them its fibres are of the striped variety, just as the circular fibres of the iris are. 
 
 f The size and shape of the pupil vary in different animals. In the bullock, 
 sheep, horse, etc., it is oblong ; in carnivorous quadrupeds it is often a mere vertical 
 slit during the day, but dilates into a large circle at night. 
 
 J The diameter of the pupil in man varies from the ^th to the | of an inch. 
 
DISSECTION OP THE EYE. 639 
 
 arches, leaving elongated interspaces, which are most marked 
 towards the middle of the iris. 
 
 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 iridis} converge 
 towards the pupil, where they form arches and blend with the 
 circular fibres ; the .circular ($phincter\ well marked, are collected 
 on the posterior aspect of the pupillary margin, where they form 
 a ring about ^th of an inch in width.* 
 
 A considerable amount of connective tissue is present in the 
 iris, forming the stroma, and consists of circular and radiating 
 fibres; the circular are found at the circumference of the iris, the 
 radiating converge towards the pupil. In front of the iris is a 
 thin layer of epithelium, .which is continuous with that covering 
 the membrane of Descemet. 
 
 When minutely injected, the iris appears to be composed almost 
 entirely of blood-vessels ; they form, in the ciliary muscle at the 
 outer circumference of the iris, a vascular circle (the circulus 
 'major}, from which numerous small branches pass inwards, and 
 form another circle (circulus minor\ which terminates -in the 
 veins of the iris. 
 
 Its blood-vessels are derived from two sources the posterior 
 or long, and the anterior ciliary arteries. The long ciliary arteries, 
 two in number, perforate the sclerotica on < each side of the optic 
 nerve, and then run forwards upon the choroid to the ciliary muscle ; 
 here they divide into branches constituting the circulus major, 
 just described : the anterior, five or six -in number, are derived 
 from the muscular branches, and ramify on the tendons of the recti 
 muscles (p. 212), where they perforate the sclerotica behind the 
 margin of the cornea. These vessels supply -the ciliary processes 
 and iris, and it is from their enlargement that the red zone round 
 the cornea is produced in inflammation of the iris. 
 
 CILIARY The nerves of the iris, about fifteen in number, 
 
 NERVES. proceed from the lenticular ganglion, and from 
 
 * The circular fibres of the iris in the bird are of the striped variety, and discern- 
 ible without difficulty. 
 
640 DISSECTION OF THE EYE. 
 
 the nasal branch of the ophthalmic division of the fifth nerve 
 (p. 213). They perforate the back of the sclerotica like the 
 arteries, run along the choroid which they supply in their course, 
 and then break up into a fine non-medullated plexus, which 
 supplies the ciliary muscle and iris. 
 
 MEMBBANA Until the seventh or eighth month of foetal 
 
 PUPILLABIS. life, the pupil is closed by a delicate membrane, 
 
 the membrana pupillaris. Its vessels, derived from those of 
 the iris and capsule of the lens, are arranged in loops which 
 converge toward the centre of the membrane. Quekett has 
 described this membrane, which has always been regarded as 
 a distinct structure, as identical, with the anterior layer of the 
 capsule of the lens.* 
 
 To obtain a view of the retina, the choroid 
 coat must be carefully removed while the eye is 
 under water ; this should be done with the forceps and scissors 
 on a fresh eye. The optic nerve, having entered the interior of the 
 globe through the sclerotic and the choroid, expands into the deli- 
 cate nervous tunic called the retina. In- passing through the 
 coats of the eye the nerve becomes gradually constricted and 
 reduced to one-half of its diameter ;- here it presents a round 
 disk, called the porus -opticus, in the centre of which may be seen 
 the arteria centralis retina3. At this point, too, the nerve-sub- 
 stance projects slightly into the interior of the globe, forming a 
 little prominence, to which the term colliculus nervi optici has been 
 applied.-J- In front the retina terminates a little behind the poste- 
 rior margin of the ciliary processes in a thin serrated border (ora 
 serrata). 
 
 Precisely opposite the pupil, in the centre of the^ axis of 
 vision, there is an oval yellow spot, maeula lutea, in the retina, 
 about gVth of an inch in diameter, fading off gradually at the 
 edges, and having a black spot, .fovea centralis, in the centre. 
 
 * See a paper by John Quekett in the 'Transactions of the Microscopical Society 
 of London,' vol.'.iii. p. .9. 
 
 ft This- prominence is- remarkable in that it -is insensible to the rays of light. It is 
 termed the ' blind spot.' 
 
DISSECTION OP THE EYE. 
 
 641 
 
 Here vision is the most perfect ; so then it might be called the 
 "spot of sight." This central spot was believed by its discoverer, 
 Sommering, to be a perforation ; but it is now ascertained to be 
 due to the pigmentary layer of the retina showing through it. 
 These appearances are lost soon after death, and are replaced by a 
 
 FIG. 163. 
 
 8. Layer of pigment cells. 
 
 7. Layer of rods and cones. 
 (Membrana Jacobi.) 
 
 Membrana limitans ext. 
 
 6. Outer nuclear layer. 
 
 5. Outer molecular layer. 5 
 
 4. Inner nuclear layer. 
 
 3. Inner molecular layer. 
 
 2. Layer of nerve-cells. 
 1. Layer of nerve-fibres. 
 
 Membrana limitans interna. 
 
 DIAGRAM OF THE VARIOUS LAYERS OF THE RETINA. (After Quain.) 
 
 minute fold, into which the retina gathers itself, reaching from 
 the centre of the spot to the prominence of the optic nerve.* 
 
 * In birds the retina has throughout the yellowish colour seen only at one part in 
 the human eye. 
 
 T T 
 
642 DISSECTION OP THE EYE. 
 
 MIOTTE STEUC- Although to the naked eye the retina appears 
 TUBE OF THE a simple, soft, semi-transparent membrane, yet, 
 
 KETINA. when examined under the microscope, it is found 
 
 to be most minutely and elaborately organised. It varies in 
 thickness from the -yV to the ^tr of an inch, being thickest behind 
 and gradually diminishing towards the front. It consists of eight 
 layers, through which may be traced a considerable amount of 
 extremely delicate connective tissue (fibres of Miiller), which 
 constitutes a scaffolding for the various strata, and is said to form 
 for them two more or less continuous boundary lines termed 
 membrance limitantes, internet, and externa. The layers are as 
 follows, beginning from within : 
 
 1 . The layer of nerve-fibres is composed of the spreading out 
 of the optic nerve-fibres and of connective-tissue cells. The nerve- 
 fibres, consisting only of the axis-cylinders, run forwards as a con- 
 tinuous layer, and, in fact, become connected with the nerve-cells 
 of the next layer. The fibres are absent on the yellow spot. 
 
 2. The ganglionic layer is a single stratum of spheroidal 
 nerve-cells : from the deeper part of each cell there is given off 
 an elongated process, which passes obliquely into the nerve-fibre 
 layer, with which it becomes incorporated ; from the opposite side 
 of the cell two or more processes pass outwards and become lost in 
 layer No. 3. The ganglionic cells which, in the greater extent form 
 a single layer, are at the yellow spot arranged eight or ten deep. 
 
 3. The inner molecular layer is a granular stratum of con- 
 siderable thickness, with a structureless matrix. In it are found, 
 also, the processes of the cells of the preceding layer, and some 
 varicose filaments which pass inwards from the next stratum. 
 
 4. The inner nuclear layer is said to contain three or four 
 kinds of cells, some of which belong to the Mullerian or connect- 
 ing tissue fibres of the retina ; others, the more numerous, are 
 bipolar nerve-cells. It is hard to give an intelligible description 
 of this layer, so long as even experts make such different state- 
 ments concerning it. 
 
 5. The outer molecular or internuclear layer resembles in 
 most respects the inner molecular layer, but is much thinner. 
 
DISSECTION OP THE EYE. 643 
 
 6. The outer nuclear layer consists of a considerable thickness 
 of nucleated cells, with an outward and an inward filament, which 
 may be recognised as connected respectively with the rods and 
 cones of the next layer. The rod-granules are the most numerous, 
 and each has an enlargement which presents a well-marked trans- 
 verse striation ; from this enlargement one varicose filament 
 passes inwards and becomes connected with the outer molecular 
 layer ; the other becomes continuous with a rod. The cone- 
 granules are fewer and thicker, and, like the rod-granules, one end 
 terminates in the outer molecular layer, the other passes into the 
 base of a cone. 
 
 7. The rods and cones, bacillary layer, or Jacob's membrane, 
 is composed of minute cylindrical elements arranged at right 
 angles to the surface of the retina. The rods, the more nume- 
 rous, are tapering processes running through the whole thickness 
 of this layer, and externally are embedded to a greater or less 
 depth in the pigmental layer, so that when viewed from without 
 they have the appearance of mosaic pavement. Among the rods 
 are intermingled numerous shorter flask-shaped bodies, called 
 cones ; their outer extremities taper off towards the choroid, their 
 inner broad ends are connected with the fibres of Mu'ller and the 
 outer nuclear layer. The rods are absent at the yellow spot. 
 
 8. The pigmentary layer is usually described as forming part 
 of the choroid coat, but it should be included more properly as 
 one of the layers of the retina. It consists of a single layer of 
 hexagonal nucleated cells filled with pigment-granules, which are 
 most numerous towards the margins of the cells. The use of the 
 pigment is to absorb the rays of light which pass through the 
 retina, and thus prevent their being reflected. It serves the same 
 purpose as the black paint with which the inside of optical instru- 
 ments is darkened. Albinoes, in whom this layer has little or no 
 pigment, are, consequently, dazzled by daylight and see better in 
 the dusk.* 
 
 * 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 
 
 T T 2 
 
644 DISSECTION OF THE EYE. 
 
 The arteria centralis retince, after emerging through the 
 porus opticus, divides into two branches an upper and a lower 
 which then form a delicate network of blood-vessels throughout 
 the nerve-fibre layer, penetrating as far as the inner nuclear layer, 
 beyond which no capillaries can be traced. After maceration in 
 water, the nervous substance can be removed with a camel's 
 hair brush, and then in an injected eye the network formed by the 
 vessels can be distinctly seen. The arteries of the retina do not 
 communicate directly with the choroidal vessels. 
 
 c, The various layers of the retina are thinner at 
 
 STRUCTURE OF J 
 
 THE MACULA the fovea, except the cones, which are much elon- 
 
 LUTEA AND FOVEA gated. It is destitute of rods and of the nerve- 
 CENTRALIS. f^ Ye i aver At the margin of the fovea most of 
 
 the layers are thicker than elsewhere. 
 
 AQUEOUS The aqueous humour consists of a few drops of 
 
 HUMOUR. an alkaline clear watery fluid, which fills the space 
 
 between the cornea and the lens.* The iris lies 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 rests on the capsule of the lens, so that, strictly speaking, 
 there is no interval between the opposed surfaces, hence no such 
 space really exists. This accounts for the frequent adhesions which 
 take place during inflammation of the iris, between the iris and 
 the capsule of the crystalline lens.f A delicate layer of epithelium 
 covers the posterior surface of the cornea, but nothing like a con- 
 tinuous 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 reappearance of the aqueous humour after the extraction of 
 a cataract. 
 
 retina, it probably enables 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. 
 
 * The solid constituent is mainly composed of chloride of sodium. 
 
 f Some anatomists describe the anterior chamber as lined by a serous membrane 
 called the membrane of the aqueous humour. 
 
DISSECTION OF THE EYE. 645 
 
 THE VITBEOUS ^ e vitreous body i g a transparent, gelatinous- 
 BODT AND THE looking substance, which fills up nearly four-fifths 
 HYALOID MEH- o f the interior of the globe (p. 634). It can be 
 easily separated from the retina, except at the 
 optic disc; in front it presents a deep depression, in which 
 the crystalline lens is embedded. It is surrounded by a delicate 
 transparent membrane, the hyaloid membrane, which forms a 
 capsule for the vitreous body, and is sufficiently strong to keep it 
 in shape after the stronger tunics of the eye have been removed. 
 
 When the vitreous humour has been hardened in chromic 
 acid it is rendered somewhat opaque, and presents, especially at 
 its outer part, a lamellar appearance. It consists of a fluid con- 
 tained in the meshes of a cellular structure, which communicate 
 freely with each other ; for if any part of it be punctured, the 
 humour gradually drains away.* If examined carefully, the 
 lamellation is seen to be arranged concentrically, the layers, as 
 they approach the centre, becoming less firm in consistence. The 
 vitreous, moreover, on a transverse section shows a radial striation, 
 but whether this exists naturally, or is the result of post-mortem 
 changes, or from chemical reagents, is not known. Running 
 through the middle from before backwards is a small canal 
 canal of Stilling about a line in diameter, 
 which contains fluid, and is broader behind 
 than in front; this in the foetus lodges a 
 small branch of the retinal artery, which 
 ramifies on the back of the capsule of the lens. 
 
 Surrounding the hollow 
 ZONE OF ZINN. . . 
 
 in the vitreous which re- 
 
 ceives the crystalline lens is the zone of 
 
 Zinn.\ This zone is best exposed by remov- AETE * IES OF THE RETINA ' 
 
 ing the ciliary processes. It appears as a canai of Petit (inflated). 
 
 11 T ,- i- i if J.T- Zone of Zinn (exaggerated). 
 
 dark, radiating disk, and extends from the 
 
 front margin of the retina nearly to the capsule of the lens ; 
 
 * This is composed mainly of water, with albuminate of soda, and muciii. 
 f Zinn was Professor of Anatomy at Gb'ttingen about the middle of the eighteenth 
 century, and author of ' Descriptio Anat. Oculi Humani.' 
 
DISSECTION OF THE EYE. 
 
 its surface is marked by prominent ridges, which correspond with 
 the intervals between the ciliary processes (fig. 164). It assists 
 in maintaining the lens in its proper position, and is firmly 
 connected with its capsule. 
 
 CANAL OF If the transparent membrane between the zone 
 
 PETIT, of Zinn and the margin of the lens be carefully 
 
 punctured, and the point of a small blow-pipe gently introduced, 
 and air or fluid injected, we may succeed in inflating a canal which 
 encircles the lens : this is the canal of Petit, or ' canal godronne ' 
 (fig. 164). This canal is usually described as formed by the 
 separation of the hyaloid membrane into two layers ; the anterior 
 the zone of Zinn being continued forwards in front of the lens, 
 the posterior passing behind it. 
 
 CRYSTALLINE The crystalline lens (fig. 161) is a perfectly 
 
 LENS - translucent solid body, situated immediately be- 
 
 hind the pupil, and partly embedded in the vitreous body. It is 
 convex on both sides, but more so behind. 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 transverse 
 diameter is about one-third of an inch ; its antero-posterior, one- 
 fifth of an inch. 
 
 The lens is surrounded by a capsule equally translucent as 
 itself. The capsule is brittle, and is composed of a structure 
 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 its capsule.* The lens protrudes directly the capsule 
 is sufficiently opened. 
 
 MINUTE STKUO The minute structure of the lens can only be 
 
 TUBE OF THE made out after being hardened. It is soft, almost 
 
 gelatinous in consistence outside, but each suc- 
 
 * The vessel of the capsule of the lens is 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. This small artery passes 
 forwards through the canal of Stilling to the posterior part of the capsule of the 
 lens, on which it radiates into numerous small branches, communicating with branches 
 in the iris and pupillary membrane. 
 
DISSECTION OF THE EYE. 647 
 
 cessive layer becomes more dense, so that the central part is hard, 
 and constitutes the nucleus. It is seen to be 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 com- 
 posed of numerous concentric layers, arranged one within the 
 other, like the coats of an onion. If any single layer be examined 
 with the microscope, it is seen to be composed of fibres about 
 5 pip o th of an inch in thickness, running in a curved direction, 
 and connected together by finely serrated edges. On a transverse 
 section the lens fibres are found to be hexagonal prisms, with very 
 little connecting substance. Between the front of the lens and its 
 capsule is a layer of flattened cells with well-marked excentric 
 nuclei. The beautiful dove-tailing of the fibres of the lens was 
 first pointed out by Sir David Brewster ; and to see it in perfec- 
 tion, one ought to examine the lens of the cod-fish. 
 
 The function of the lens is to bring the rays of light to a focus 
 upon the retina.* 
 
 * The lens contains about 60 per cent, of water, and 30 per cent of albuminoids. 
 
648 
 
 DISSECTION OF THE ORGAN OF HEARING. 
 
 THE parts constituting the organ of hearing should be examined 
 in the following order: 1. 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 semi-circular canals. 
 
 The pinna or auricle is irregularly oval, and 
 presents on its external aspect numerous eminences 
 and hollows, which have received the following names : The cir- 
 cumferential folded border is called the helix ; the ridge within it, 
 the antihelix ; between these is a curved groove, called the fossa 
 of the helix. The antihelix bifurcates towards the front, and 
 encloses the fossa, of the antihelix. The conical eminence in front 
 of the meatus is termed the tragus, on which some hairs are 
 usually found. Behind the tragus, and separated from it by a 
 deep notch (incisura intertragica), is the antitragus. The lobule 
 is the soft pendulous part, and consists of fat and fibrous tissue. 
 The deep hollow, which collects the vibrations of sound, and con- 
 veys them into the external meatus, is termed the concha. The 
 pinna is composed of yellow fibre-cartilage, with a little fat and 
 cellular tissue. It is attached by an anterior ligament to the root 
 of the zygoma, and by a posterior to the mastoid process of the 
 temporal bone. When the skin of the pinna is removed, we find 
 that the cartilage has a tubular prolongation inwards, which forms 
 the external part of the meatus auditorius. It does not, however, 
 form any part of the lobule, and is incomplete behind the tragus, 
 the deficiency being filled up with fibrous tissue. The cartilage 
 further presents several fissures (fissures of Santorini) at the 
 anterior part of the tubular prolongation, which are completed by 
 firm fibrous tissue. 
 
DISSECTION OF THE ORGAN OF HEARING. 649 
 
 MUSCLES OF The muscles which move the cartilage of the 
 
 THE PINNA. ear as a wno le, have been described (p. 2). Other 
 small 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 four on the 
 front of the auricle and two behind it are usually described : 
 
 (a.) The musculus major helicis runs vertically along the 
 
 front margin of the helix. 
 (6) The musculus minor helicis lies over that part of the 
 
 helix which is connected with the concha. 
 
 (c) The musculus tragicus lies vertically over the outer surface 
 
 of the tragus. 
 
 (d) The 'musculus antitragicus passes transversely from the 
 
 antitragus to the lower part of the antihelix. 
 
 (e) The musculus transversus is on the cranial aspect of the 
 
 pinna ; it passes nearly transversely 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 
 auricular, and from the auricular branches of the temporal 
 and occipital. The veins empty themselves into the temporal 
 vein. The nerves are furnished by the auriculo-parotidean branch 
 of the superficial cervical plexus, the auriculo-temporal branch of 
 the inferior maxillary, the posterior auricular branch of the facial, 
 and the auricular branch of the pneumogastric. 
 
 MEATUS AUDI- This passage leads down to the membrana 
 TOEIUS EXTEBNUS. tympani, and conveys the vibrations of sound to 
 the tympanum. It is about an inch and a quarter in length ; its 
 external opening is longest in its vertical direction : its termina- 
 tion is broadest in its transverse. The canal inclines at first 
 upwards and forwards, and then curves a little downwards.* Its 
 
 * 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 be taken of it in 
 plaster-of-Paris. 
 
650 DISSECTION OF THE ORGAN OF HEARING. 
 
 floor, owing to the "oblique direction of the membrana tympani, is 
 a little longer than the roof. It is not of equal calibre throughout, 
 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 
 cartilage of the auricle, partly, by an osseous canal in the temporal 
 bone. The cartilaginous portion is about half an inch long and 
 is firmly connected with the osseous portion, which is about 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 membrana tympani. The outer portion is furnished with 
 hairs and ceruminous glands which secrete the cerumen or wax, 
 and are only found over the cartilaginous portion of the canal. Its 
 arteries are derived from the posterior auricular, internal maxillary 
 and temporal ; its nerve from the auriculo-temporal. 
 T The tympanum, or middle ear, is an irregular 
 
 cavity in the petrous part of the temporal bone, 
 and separated from the external auditory meatus by the membrana 
 tympani. It is lined with mucous membrane and filled with air, 
 which is freely admitted through the Eustachian tube ; so that 
 the atmospheric pressure is equal on both sides of the membrane. 
 A chain of small bones, retained in their position by ligaments 
 and acted upon by muscles, passes across it. The use of these 
 bones is to communicate the vibrations of the membrana tym- 
 pani to the labyrinth. For this purpose one end of the chain is 
 attached to the membrane, the other to the fenestra ovalis. The 
 antero- posterior diameter of the tympanum is rather less than half 
 an inch, its vertical and transverse diameters about a quarter of an 
 inch. The cavity is bounded by a roof, a floor, an outer, an inner, 
 an anterior, and a posterior wall. Its roof is formed by a thin 
 plate of bone corresponding with the anterior surface of the pars 
 petrosa ; its floor, by a thin plate, which forms the jugular fossa. 
 Its outer wall is formed by the membrana tympani, and partly by 
 bone ; the latter is pierced by the fissura Grlaseri (which gives passage 
 to the processus gracilis of the malleus and the laxator tympani), 
 and by the canal of Huguier for the exit of the chorda tympani 
 
DISSECTION OF THE OEGAN OP HEAEING. 651 
 
 nerve. The inner wall presents the following objects, beginning 
 from above : 1. A ridge, indicating the line of the aqueductus 
 Fallopii ; 2. The fenestra ovalis, which leads into the vestibule, 
 but is closed in the recent state by a membrane, to which is 
 attached the base of the stapes ; 3. 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 ; 4. Below and behind 
 this, is the fenestra rotunda ; it leads into the scala tympani of 
 the cochlea, but is closed in the recent state by membrane ; 
 5. Immediately behind the fenestra ovalis, is a small conical 
 eminence, named the pyramid, in the summit of which is a small 
 aperture, from which the tendon of the stapedius emerges. 
 
 The posterior wall presents three or four openings, which 
 lead into the mastoid cells, and convey air into them from the 
 tympanum ; also a small foramen, foramen chordce posterius, for 
 the passage of the chorda tympani nerve. 
 
 The anterior wall leads to the Eustachian tube, and (in the dry 
 bone) to the canal for the tensor tympani, which are separated 
 from each other by a bony septum, the processus cochleariformis. 
 
 Lastly, a nerve called the chorda tympani (a branch of the 
 portio dura) runs across the cavity, covered by mucous membrane. 
 MEMBRANA The membrana tympani is a thin semi- 
 
 TYMPANI. transparent disk which completely closes the 
 
 bottom of the meatus auditorius externus. 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 down- 
 wards, forming, with the floor of the meatus, an angle of 55. 
 It is slightly conical, the apex being directed inwards towards the 
 tympanum, and between its layers is inserted the handle of the 
 malleus. It is composed of three layers : an outer, formed by 
 an extremely thin layer of true skin ; an inner, by the mucous 
 membrane of the tympanum ; and a middle layer, consisting of 
 fibrous tissue ; some of the fibres radiate from the centre, others 
 are circular, forming a circumferential ring close to the osseous 
 
652 DISSECTION or THE ORGAN OP HEAKING. 
 
 groove. The membrane is supplied with blood from the tympanic 
 branch of the internal maxillary, the stylo-mastoid branch of the 
 posterior auricular, and the Vidian. 
 
 EUSTACHIAN For a complete account of the Eustachian tube 
 
 TUBE. (see p. 186). It proceeds from the anterior part 
 
 of the tympanum, downwards, forwards, and inwards, to the 
 pharynx. 
 
 OSSICULA The three small bones in the tympanum are 
 
 AUDITUS. named after their fancied resemblance to certain 
 
 implements, the malleus, incus, and stapes. They are articulated 
 FIG. 165. 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 within the vestibule. 
 But they have another use, which would be 
 THE OSSICLES OF THE EIGHT incompatible with a single bone namely, 
 TYMPANUM. to p erm it the tightening and relaxation of 
 
 A. Malleus. B. Incns. ,, , , ,, , , ., .,, 
 
 c. stapes, it lies horizontally the membrane, and thus adapt it either to 
 
 and forms a right angle with .in- if i > 
 
 the long process of the incus, resist the impulse of a very loud sound, or 
 to favour a more gentle one. 
 
 The malleus, or hammer bone, consists of an upper part or 
 head, which is suspended to the roof of the tympanum by the sus- 
 pensory ligament, and articulates posteriorly with the incus. From 
 it proceeds the handle, which is nearly vertical, and is attached 
 along its whole length to the upper half of the membrana tympani. 
 The long process (processus gracilis) projects at right angles from 
 the head of the malleus, runs into the Grlaserian fissure, and 
 receives the insertion of the laxator tympani. The processus 
 brevis, situated at the junction of the long process and the head, 
 looks towards the membrana tympani, and receives the insertion of 
 the tensor tympani. 
 
 The incus, or anvil bone, is shaped like a tooth with two unequal 
 widely separated fangs. Its broad part or body presents a concavo- 
 convex articulation for the head of the malleus ; its long process 
 
DISSECTION OF THE OEGAN OF HEABING. 653 
 
 runs nearly parallel with the handle of the malleus, and articulates 
 with the stapes through the intervention of a small bone, the os 
 orbiculare, which, in adult life, forms part of the long process, but 
 in foetal life is a separate bone ; its short process is directed back- 
 wards, and its point is fixed in a small hollow at the commence- 
 ment of the mastoid cells. 
 
 The stapes, or stirrup bone, lies horizontally. Its head articulates 
 with the long process of the incus. Two diverging crura pass 
 from the head to the base, which is attached to the membrane 
 covering the fenestra ovalis. The stapedius muscle is inserted 
 into the posterior part of its neck. 
 
 The tympanic bones are maintained in their positions by 
 various ligaments. The anterior ligament of the malleus passes 
 from the head of this bone to the anterior wall of the tympanum ; 
 the suspensory ligament descends from the roof of the tympanum 
 outwards to the head of the malleus, and the posterior ligament 
 of the incus passes from the short process to the posterior wall near 
 the mastoid cells. The ossicles are connected by an imperfect 
 capsular ligament, which passes from' the long process of the 
 incus to the head of the stapes ; and by another which passes 
 from the head of the malleus to the incus. The surfaces of the 
 bones forming these two little joints are covered with cartilage. 
 The joints have also synovial membranes. 
 
 The muscles, by moving the tympanic bones, tighten or relax 
 MUSCLES OF the membrana tympani. The tensor tympani 
 THE TYMPANUM. runs in a canal above and parallel to the Eustachian 
 tube, from the cartilaginous part of which it arises, as well as from 
 the apex of the petrous portion of the temporal bone. It passes 
 backwards, and terminates in a round tendon, which enters the 
 front wall 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 inwards the 
 head of the malleus, and thus render the membrane tense. The 
 laxator tympani arises from the spinous process of the sphenoid, 
 and the Eustachian tube, and is inserted into the neck of the 
 malleus close to the root of the processus gracilis. It is supplied 
 
654 DISSECTION OP THE ORGAN OF HEARING. 
 
 by a branch of the facial nerve.* Its action is to relax the mem- 
 brana tympani. The stapedius arises from the hollow of the 
 pyramid, and its tendon runs forwards to be inserted into the 
 neck of the stapes, f Its nerve is derived from the facial. By 
 its action it increases the tension upon the fluid in the vestibule. 
 
 The tympanum is lined with mucous membrane, which is 
 continuous with that of the pharynx. It covers the ossicles, and 
 is prolonged into the mastoid cells. The membrane is pale and 
 thin, and lined with columnar ciliated epithelium, except on the 
 promontory, the membrana tympani, and the ossicles, where there 
 is only a single layer of flattened cells. 
 
 CHORDA TTM- A branch (chorda tympani) of the facial nerve 
 
 PANI. enters the tympanum through a foramen at the 
 
 base of the pyramid (foramen chordae posterius) ; it then crosses 
 the tympanum between the handle of the malleus and the long 
 process of the incus, leaves the tympanum through a foramen 
 (foramen chordae anterius), and then traverses a canal (canal of 
 Huguier\vfhich runs close to the Grlaserian fissure. It eventually 
 joins the submaxillary ganglion (p. 51). 
 
 BLOOD-VESSELS The tympanum is supplied with blood 1, by 
 OF THE TYM- the tympanic branch of the internal maxillary, 
 
 PANTJM. which enters through the fissura Grlaseri ; 2, by 
 
 the stylo-mastoid branch of the posterior auricular ; 3, by small 
 branches from the ascending pharyngeal, 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. 
 
 The mucous membrane is supplied with branches from the 
 tympanic plexus, which is formed by filaments from the tympanic 
 branch of the glosso-pharyngeal nerve, from the carotid sympathetic 
 plexus, and from the large and small superficial petrosal nerves. 
 
 This, in consequence of its complexity, is called 
 
 INTERNAL EAR. 7 , . , 1. r " 
 
 the Labyrinth. It consists 01 cavities excavated 
 
 * This is usually regarded as a muscle, and is described here as such ; no mus- 
 cular fibres, however, can be traced in it, so that it is probably only ligamentous in 
 structure a fact borne out in the lower animals. 
 
 f There is a little sheath, lined with synovial membrane, to facilitate the play of 
 the tendon in the pyramid. 
 
DISSECTION OF THE ORGAN OF HEARING. 
 
 655 
 
 in the most compact part of the temporal bone. The cavities are 
 divided into three a middle one, called the vestibule, being a 
 centre in which all communicate ; an anterior, named from its 
 resemblance to a snail's shell, the cochlea ; and a posterior, con- 
 sisting of three semicircular 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, is an irregular 
 oblong cavity, about one-fifth of an inch in its 
 widest part. It communicates in front with the cochlea, through 
 
 FIG. 166. 
 
 VESTIBULE. 
 
 1. The superior semicir- 
 
 cular canal. 
 
 2. The posterior semicir- 
 
 cular canal. 
 
 3. The external semicir- 
 
 cular canal. 
 
 4. Common opening of the 
 
 superior and posterior 
 semicircular canals. 
 
 5. Aqueductus vestibuli. 
 
 6. Aqueductus cochleae. 
 
 7. Fovea hemi-elliptica. 
 
 8. Fovea hemispherica. 
 
 9. Scala tympani. 
 10. Scala vestibuli. 
 
 OSSEOUS LABYRINTH OF THE EIGHT SIDK 
 
 the scala vestibuli ; behind, with the five openings of the semi- 
 circular canals ; on the outside with the tympanum, through the 
 fenestra ovalis ; on the inside is a shallow depression, the fovea 
 hemispherica, through which are transmitted the branches of the 
 auditory nerve. Posteriorly, this depression is bounded by a ridge, 
 the crista vestibuli, and in some subjects there is behind this 
 eminence the opening of a small canal, called the aqueductus 
 vestibuli. It leads to the posterior surface of the temporal bone, 
 and transmits a small vein. In the roof is an oval depression, the 
 fovea hemi-elliptica, which lodges the utricle. 
 
 SEMICIRCULAR The semicircular canals, three in number, are 
 
 CANALS. situated above, and rather behind the vestibule. 
 
656 DISSECTION OF THE ORGAN OF HEARING. 
 
 Each canal forms about two-thirds of a circle, and is about one- 
 twentieth of an inch in diameter. 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 extremities of two canals. The canals are not of equal 
 diameter throughout ; each presents at one end a dilatation termed 
 the ampulla, about one-tenth of an inch in diameter. This dila- 
 tation 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 extremity. Its non-ampullated extremity 
 
 FIG. 167. 
 
 1. Scala tympani. B^^iMiH^^ 3. Lamina spiralis 
 
 ~L-^4^KhEJ3 Hn ossea. 
 
 2. Scala vestibuli. ^3S.H Bp * 
 
 4. Modiolus, or central 
 pillar. 
 
 THE OSSEOUS COCHLEA. 
 
 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 consequently, 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. 
 
 The cochlea is the most anterior part of the 
 internal ear : it very closely resembles a common 
 snail's 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. Its base is about a quarter of 
 an inch in diameter. It consists of the spiral convolutions of two 
 parallel and gradually tapering tubes, which wind round a central 
 pillar, called the modiolua. The partition by which the tubes, 
 
DISSECTION OF THE ORGAN OF HEARING. 657 
 
 scalce, are separated is termed the lamina spiralis. In the dry 
 bones this partition is only partial ; but in the recent state it 
 is completed by a membrane. The spiral canal is about the T ^ of 
 an inch in diameter, and is about one inch and a half long, and, 
 after making two turns and a half, terminates at the apex of the 
 cochlea in a rounded dome, the cupola. Here the partition dis- 
 appears, and is called the helicotrema, so that the two scalae com- 
 municate with each other in this situation. These tubes are 
 called the scales of the cochlea, and are filled with fluid. The 
 upper one, the scala vestibuli, opens into the vestibule ; the 
 lower one, rather the larger of the two, is called the scala tym- 
 pani, and leads to the membrane which closes the foramen ro- 
 tundum of the tympanum. At its commencement there is the 
 opening of the aqueductus cochleae, which transmits a small 
 branch to the jugular vein. 
 
 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, 
 which transmit small vessels and nerves to the lamina spiralis. 
 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 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, 
 (lamina spiralis ossea} ; on the outer half, of membrane, which, 
 as will be presently described, consists of two layers. The lamina 
 spiralis ossea ends at the cupola in a hook-line process, the hamulus. 
 On a vertical section it is seen to be composed of two plates, 
 between which the structure is spongy, and presents a number of 
 small canals for the passage of the small filaments of the cochlear 
 division of the auditory nerve in their course to the membranous 
 part of the lamina. Winding round the modiolus, close to the 
 attachment of the lamina spiralis ossea, is a small canal, called the 
 canalis spiralis modioli. 
 
 MEMBRANOUS If the bony labyrinth just described be properly 
 
 LABYEINTH. understood, there will not be much difficulty in 
 
 u u 
 
658 DISSECTION OP THE ORGAN OF HEARING. 
 
 comprehending the shape of the membranous labyrinth in its 
 interior, a structure supporting the ultimate ramifications of the 
 auditory nerve. The membranous labyrinth floats in a fluid 
 called the peri-lymph or liquor Cotunnii, which is secreted by the 
 delicate serous membrane lining the osseous labyrinth. 
 
 The membranous labyrinth is a sac, contained partly in the 
 vestibule and 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 sac in the vestibule is so constructed as to form two sacs 
 of unequal size, which indirectly communicate with each other.* 
 The larger of the two, called the utricle or common sinus, is 
 oval, and communicates with the five openings of the membranous 
 semicircular canals. It is lodged in the fovea hemielliptica, and 
 its wall is thickest close to the crista vestibuli, where branches from 
 the auditory nerve enter it. The smaller, called the saccule, is 
 globular and flattened, and lies in the fovea hemispherica, in front 
 of the utricle. It is connected with the membranous canal of the 
 cochlea by a small short duct, termed ihe~canalis reuniens. 
 
 The utricle and the saccule contain on their inner wall a minute 
 mass of calcareous matter in connection with nerve ends, called 
 by Breschet the otoliths or otoconia. They are crystals of car- 
 bonate of lime, and are present in the labyrinth of all mammalia. 
 From their greater hardness and size in aquatic animals, there is 
 reason to believe that they perform the office of rendering the 
 vibrations of sound sharper and more distinct.f 
 
 MEMBRANOUS The membranous semicircular canals present 
 
 SEMICIRCULAR the same dilatations or ampullas as the bony ones, 
 
 at one end, and at this part they nearly fill their 
 
 * From the utricle there proceeds a small canal, -which lies in the aqueductus 
 vestibuli ; this is joined close to its commencement by a similar canal from the 
 saccule ; thus forming the indirect communication above alluded to. 
 
 t For a detailed description of the relation of the otoliths with the hair-like 
 processes of the nerve-filaments, the student is referred to an article by Dr. Urban 
 Pritchard in the 'Quarterly Journal of Microscopic Science,' October, 1876, entitled 
 'The Termination of the Nerves in the Vestibule, and Semicircular Canals of 
 Mammals.' 
 
DISSECTION OF THE OUGAN OP HEARING. 659 
 
 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. 
 At the ampullated extremity the sac is connected on its outer 
 aspect by blood-vessels and nerves to the periosteum, forming, on 
 section, a septum, called the septum transversum. 
 
 The membranous labyrinth is protected, inside and out, by 
 fluid. The fluid in the interior is termed the endolymph, and 
 the thin layer between it and the bone, the perilymph or liquor 
 Cotunnii', thus the delicate nervous membrane is placed between 
 two layers of fluid. 
 
 DISTRIBUTION The auditory nerve or portio mollis of the 
 
 OF THE AUDITORY seventh pair, passes down the jneatus auditorius 
 internus, and at the bottom of it, divides into an 
 anterior and posterior branch, which, after breaking up into 
 numerous fasciculi, are distributed to the cochlea and to the 
 vestibule. 
 
 The vestibular nerve divides into five branches, which pro- 
 ceed to the utricle, the saccule, and the three ampullae of the 
 semicircular canals, respectively : those for the utricle, and the 
 superior and external semicircular canals enter the vestibule along 
 the crista vestibuli ; that for the saccule enters through the fovea 
 hemispherica, and that for the posterior semicircular canal is con- 
 tinued along a bony canal to its termination. The nerves to the 
 semicircular canals enter the ampullae by a forked swelling which 
 corresponds to each septum transversum. 
 
 The membranous semicircular canals consist of three layers, 
 an outer or fibrous layer, which is connected with the periosteum 
 by blood-vessels, and contains irregular pigment-cells ; a middle or 
 tunica propria, clear and structureless ; and an inner or epithelial 
 layer, which lines the inner space of the tunica propria. At the 
 ampullse the epithelial layer is composed of the columnar variety, 
 upon which are arranged cells of a spindle shape, having delicate 
 ciliated processes (auditory hairs} projecting into the endolymph. 
 
 It has been stated that in the bony cochlea there is a partial 
 septum, dividing the spiral tube into two incomplete scalae. In the 
 recent condition, however, the osseous lamina spiralis is continued 
 
 ru 2 
 
660 DISSECTION OF THE ORGAN OF HEARING. 
 
 outwards by a thick membrane, the basilar membrane (fig. 168) ; 
 thus dividing the tube into an upper canal, the scala vestibuli, 
 and a lower, the scala tympani. The upper scale is subdivided by 
 an oblique membrane membrane of Reissner into two canals, 
 an inner, the scala vestibuli) and an outer, the ductus cochlearis. 
 The ductus cochlearis or scala media terminates at the helicotrema 
 in a cul-de-sac ; inferiorly it is connected with the cavity of the 
 saccule by a long, narrow duct, called the canalis reuniens. 
 
 On examining the membranous continuation of the lamina 
 spiralis, it is seen, not far from its attachment to the osseous zone, 
 
 FIG. 168. 
 
 DIAGRAMMATIC SECTION OF A COIL OF THE COCHLEA. 
 
 (From Quain.) 
 
 s v. Scala vestibuli. r c. Rods of Corti. 
 
 D c. Ductus cochlearis. m b. Membrana basilaris. 
 
 S T. Scala tympani. Is p. Ligamentum spirale. 
 
 m H. Membrane of Beissner. s s. Sulcus spiralis. 
 
 Us. Limbus laminae spiralis. g s. Ganglion spirale. 
 m T. Membrana tectoria. 
 
 to be thickened into an elongated crest, the limbus, which over- 
 hangs a groove, called the sulcus spiralis. The structure of the 
 limbus consists of firm connective tissue, on the under part of which 
 are found numerous cells. The basilar membrane forms, at the 
 base of the cochlea, but a small breadth of the septum, the broadest 
 part being formed of bone, but it gradually increases in breadth 
 towards the cupola, where it constitutes nearly the entire septum. 
 
DISSECTION OF THE ORGAN OP HEARING. 661 
 
 It consists of a firm, fibrillated tissue, which is probably formed, at 
 any rate on its upper surface, of a structure closely resembling 
 the organ of Corti. 
 
 The membrane which separates the scala vestibuli and the 
 ductus cochlearis is a delicate almost structureless layer, the mem- 
 brane of Reissner. It appears to be composed of connective tissue, 
 lined on its vestibular surface with flattened connective -tissue 
 cells, and on its cochlear surface with squarnous epithelium. 
 
 At the point of attachment of the basilar membrane with the 
 outer wall of the cochlea may be seen a triangular projection, which, 
 formerly described as a muscle, (cochlearis musvle), is now generally 
 believed to be a collection of connective-tissue cells, and called 
 the ligamentum spirale. 
 
 OHGAK OF The organ of Corti is a highly complex structure, 
 
 COBTI - placed on the upper surface of the basilar mem- 
 
 brane, and the floor of the ductus cochlearis. The central part of 
 the organ of Corti is formed by two sets of slanting rods inner 
 and outer rods of Corti* which rest against each other at their 
 upper extremities, thus forming a triangular tunnel beneath them, 
 filled in the recent state with endolymph. 
 
 On the inner side of the inner rods is a single row of cells 
 tipped with ciliated processes, called the inner hair-cells ; and on 
 the outer side of the outer rods are three rows of similar cells, 
 termed the outer hair-cells. 
 
 The only remaining membrane to be described is the tectorial 
 membrane) which lies above and parallel to the basilar membrane, 
 but does not extend much more than half-way over it. It is con- 
 nected on its inner side with the limbus spiralis, and is then con- 
 tinued outwards, overlying and resting upon the rods of Corti, 
 and ends in a free extremity. It is a strong, elastic membrane, 
 distinctly fibrous, especially upon its inner and thicker part. 
 
 The cochlear division of the auditory nerve (the vestibular has 
 already been described, p. 659) is a short, thick branch, which breaks 
 up into numerous filaments at the bottom of the meatus auditorius 
 
 * The inner rods are stated to be more numerous than the outer, in the proportion 
 of 6,000 of the inner to 4,500 of the outer rods. 
 
662 
 
 interims. These enter the canals in the base of the modiolus, and 
 then arch outwards between the plates of the lamina ossea. In 
 their course outwards between the plates, they pass through the 
 spirally arranged ganglionic cells, beyond which they form a wide 
 plexus. They are collected together close to the free border of the 
 osseous zone, forming a very minute nerve-plexus, whose filaments 
 interlace freely ; they then enter the membranous zone to be con- 
 nected with the inner hair-cells of the organ of Corti.* 
 
 The vessels which supply the cochlea are from ten to twelve in 
 number, and are derived from the auditory artery ; they, like the 
 nerves, enter the bony canals of the modiolus, and then turn out- 
 wards to ramify upon the osseous zone, supplying its periosteum. 
 The plexus formed by these branches communicates with a vessel 
 known as the vas spirale, which runs longitudinally in the liga- 
 mentum spirale to the outer attachment of the membrana basil- 
 aris. The veins from the cochlea terminate in the superior 
 petrosal sinus, having previously joined those of the vestibule and 
 semicircular canals. 
 
 * Some anatomists describe filaments as passing between the rods of Corti to end 
 in the outer hair-cells^ 
 
663 
 
 DISSECTION OF THE MAMMARY GLAND. 
 
 THE form, size, position, and other external characters of the 
 mammary gland vary more or less in different persons. The 
 longest diameter of the gland is in a direction upwards and out- 
 wards towards the axilla ; its thickest part is at the centre ; and 
 the fulness and roundness of the gland depend upon the amount 
 of fat about it. Its deep surface is flattened in adaptation to 
 the pectoral muscle, to which it is firmly connected by an abund- 
 ance of areolar tissue. In its vertical direction the breast corre- 
 sponds to the space between the third and sixth or seventh ribs ; 
 in its lateral direction, to the space between the side of the 
 sternum and the axilla, while the nipple corresponds to the fourth 
 rib, or a little below it. 
 
 It is enclosed 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 abundantly provided with 
 papillae, and with subcutaneous sebaceous glands, to lubricate 
 the surface during lactation ; the areola as well as the nipple is 
 destitute of fat. 
 
 The gland itself consists of distinct lobes held 
 
 together by firm connective tissue, and provided 
 
 with separate lactiferous ducts. Each lobe divides and subdivides 
 
664 DISSECTION OF THE MAMMARY GLAND. 
 
 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 minutely upon 
 these cells ; altogether, then, a single lobe might be compared to 
 a bunch of grapes, of which the stalk represents the main duct. 
 The main ducts (galactophorus ducts} from the several lobes, 
 from fifteen to twenty in number, converge towards the nipple, 
 and, just before they reach it, become dilated into small sacs or 
 ampullce, two or three lines wide ; after this they run up to the 
 apex of the nipple, and, running parallel, terminate in separate 
 orifices. 
 
 The vesicles and the galactophorus ducts are lined with 
 columnar epithelium, except at their orifices, where it becomes 
 squamous. 
 
 The arteries of the gland are derived from the long thoracic, 
 the internal mammary, and the intercostals ; the nerves come 
 from the anterior and lateral cutaneous branches of the intercostal 
 nerves and from the descending branches of the cervical plexus. 
 The veins diverge from the nipple, and terminate in the axillary 
 and internal mammary veins. 
 
 The lymphatics run chiefly to the axillary glands. 
 
 * It is observed, in some cases, that one or more lobules run off to a consider- 
 able distance from the main body of the gland, and lie embedded in the subcutaneous 
 tissue. This should be remembered when it is necessary to remove the entire 
 gland. 
 
665 
 
 DISSECTION OF THE SCROTUM AND TESTIS. 
 
 STRUCTURE OF THE scrotum is a pouch of skin for the lodgment 
 THE SCROTUM. of the testes, and presents in the middle line a ridge, 
 the raphe, on each side of which it is corrugated into rugae. It 
 is composed of six tunics: 1. The skin; 2. The tunica dartos ; 
 3. A layer of connective tissue ; 4. The spermatic fascia ; 5. The 
 cremaster or suspensory muscle ; 6. The infundibuliform fascia, 
 derived from the fascia transversalis. 
 
 Each of these coverings cannot be demonstrated under ordi- 
 nary circumstances, because they are so blended together ; but they 
 can be shown when hypertrophied in the case of old and large 
 herniae. 
 
 The dartos is a thin layer, consisting of mus- 
 Z)AETOS 
 
 cular fibres of the involuntary kind, like those of 
 
 the bladder and intestines. It serves to corrugate the loose and 
 extensible skin of the scrotum, and in a measure to support and 
 brace the testicles. It is more abundant in the anterior than the 
 posterior part of the scrotum. 
 
 LAYER OF CON- Beneath the dartos is a large quantity of loose 
 NECTIVE TISSUE. connective tissue, remarkable for the total absence 
 of fat. Together with the dartos, it forms a vertical partition 
 between the testicles, termed the septum scroti. It is not a com- 
 plete 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 the infundibuli- 
 form fascia have been described (pp. 359, 361, 366). 
 
666 
 
 DISSECTION OF THE TESTIS. 
 
 TESTIS. 
 
 The testicle is a gland of an oval shape with 
 flattened sides, suspended obliquely, so that the 
 upper end is directed forwards and outwards, the lower end in the 
 reverse direction. The left is generally a little the lower of the 
 two. Each testis is about an inch and a half in length, and one 
 in breadth, and weighs about six drachms ; but few organs present 
 greater variations in size and weight, even in men of the same 
 age ; generally speaking, the left is the larger. The front and 
 sides of the testes are smooth, and covered with the visceral layer 
 of the tunica vaginalis ; but along the posterior part of the gland 
 
 FIG. 169. 
 
 1. Mediastinum testis, con- 
 
 taining the rete testis. 
 
 2, 2. Trabeculse. 
 
 3. One of the lobules. 
 
 4, 4. Vasa recta. 
 
 5. Coni vasculosi, forming the 
 
 ' globus major' of the epi- 
 didymis. 
 
 6. Globus minor, or lower end 
 
 of epididymis. 
 
 7. Vas deferens. 
 
 DIAGEAM OF A VERTICAL SECTION THROUGH THE TESTICLE. 
 
 EPIDIDYMIS. 
 
 is placed a long narrow body, termed the epididy- 
 mis ; 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 with the testicle by the efferent ducts ; the lower end, 
 globus minor, is only connected with the testicle by fibrous 
 tissue ; that part of the epididymis between these two portions is 
 called the body. A considerable quantity of unstriped muscular 
 fibre exists at the posterior part of the epididymis and testig 
 beneath the infundibuliform fascia, and has been described by 
 Kolliker as the inner muscular tunic. 
 
DISSECTION OP THE TESTIS. 66? 
 
 PROPER Co- The coverings of the testicle are 1. A serous 
 
 VERINOS OF THE membrane, called the tunica viginalis, to facili- 
 TESTICLE. ^ate its movements ; 2. A strong fibrous mem- 
 
 brane, called the tunica albuginea, to support the glandular 
 structure within ; 3. A delicate stratum of minute blood-vessels, 
 which some anatomists have described as a distinct coat, under 
 the name of tunica vasculosa. 
 
 TUNICA The tunica vaginalis is a closed serous sac, one 
 
 VAGINALIS. part of which (tunica vaginalis propria) adheres 
 
 closely to the testis ; the other (tunica vaginalis reflexa) is re- 
 flected loosely around it. On opening the sac, it will be seen that 
 the visceral layer completely covers the testicle, except behind, 
 where the vessels and duct are situated (fig. 170); and that it 
 covers the outer part of the epididymis in front and behind, form- 
 ing here a pouch called the digital fossa. The parietal layer 
 extends upwards for a variable distance upon the cord. 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 ' hydrocele.' 
 
 The tunica vaginalis was originally derived from the perito- 
 neum. In some subjects it still communicates with that cavity 
 by a narrow canal, and is therefore liable to become the sac of a 
 hernia (see diagram, p. 370). Such hernise are called congenital 
 a bad term, since they do not necessarily take place at birth, 
 but may occur at any period of life, even in very old age.* Some- 
 times the communication continues through a very contracted 
 canal, open to the passage of fluid alone ; 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 
 with fluid, gives rise to hydrocele of the cord. 
 
 TUNICA This tunic is a dense, inelastic membrane, com- 
 
 ALBUGLNEA. posed of fibrous tissue, interlacing in every direc- 
 
 tion ; analogous to the sclerotic coat of the eye. It completely 
 
 * It "would be a better term to call this lesion, a hernia in the tunica vaginalis, 
 denoting thereby its anatomical position ; at the same time implying a congenital 
 arrest in development, and without limiting its occurrence to any age of life. 
 
668 DISSECTION OF THE TESTIS. 
 
 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 
 anatomist who first discovered it, corpus Highmorianum, and 
 subsequently by Sir A. Cooper, mediastinum testis (fig. 170). 
 This septum transmits the blood-vessels of the organ, and contains 
 also the network of seminal ducts, called the rete testis, shown in 
 diagram (fig. 169). 
 
 From the mediastinum testis are given off, in all directions, a 
 number of diverging slender fibrous cords, which traverse the 
 interior of the gland, and are attached to the inside of the tunica 
 
 4. Epididymis. 
 
 1. Spermatic artery. C Iffi^MSBSBSV '. 5. Mediastinum testis. 
 
 2. Vas deferens. h ifmjllWBSSL 6, 6. Cavity of tunica 
 
 3. Deferential artery. V 1^111X181 F * vaginalis. 
 
 TRANSVERSE SECTION THROUGH THE TESTICLE (diagrammatic). 
 
 (The dots show the reflections of the tunica vaginalis.) 
 
 albuginea. They serve to maintain the general shape of the testi- 
 cle, to support the numerous lobules of which its glandular sub- 
 stance is composed, and to convey the blood-vessels into it. These 
 septa (trabeculae testis) as well as the mediastinum from which 
 they proceed, are readily seen on making a transverse section through 
 the gland (fig. 170).* 
 
 TUNICA Kespecting the so-called tunica vasculosa 
 
 VASCULOSA. nothing more need be said than that it consists of a 
 multitude of minute blood-vessels, formed by the ramifications of 
 
 * Kolliker has demonstrated unstriped muscular fibres upon the septa as well as 
 the mediastinum. 
 
DISSECTION OF THE. TESTIS. 669 
 
 the spermatic artery, and held together by delicate areolar tissue. 
 It covers the inner surface of the tunica albug^iea, and gives off 
 branches, which run with the fibrous septa into the interior of the 
 gland. 
 
 MINUTE When the testis is cut into, its interior looks 
 
 STRUCTURE. so ft an d pulpy and of a reddish-grey colour. 
 
 It consists of a multitude of minute convoluted tubes tubuli 
 seminiferi which have each a length of about two feet and a 
 quarter, and a diameter averaging y^-g- of an inch. For economy 
 of space they are arranged in lobules, between three and five 
 hundred * in number, of various sizes, and contained in the 
 compartments formed by the fibrous septa proceeding from the 
 mediastinum testis. A few only of these lobules are shown in the 
 diagram. Though disposed in lobules, still they communicate 
 with each other, and thus form one large network of tubes. The 
 tubuli are lined with flattened cells of several strata in thickness, 
 resting upon a basement membrane. They commence either 
 by anastomosing loops, or by blind dilated extremities, and 
 after pursuing a convoluted course, unite into from thirty to 
 fifty straight vessels (vasa recta], which penetrate the medias- 
 tinum testis, and there form a plexus of seminal tubes, termed 
 the rete testis. This lies along the back of the gland. From the 
 upper part of the rete, the secretion is conveyed to the upper 
 part of the epididymis by twelve to fifteen tubes, termed vasa 
 efferentia, which perforate the tunica albuginea in their course to 
 the globus major. These, after forming a number of coils, termed 
 coni vasculosi,^ collectively constitute the globus major of the 
 epididymis. 
 
 At the globus major the smaller tubes terminate in a single 
 duct the canal of the epididymis, which in its descent describes 
 an extremely tortuous coil, constituting the body and globus minor 
 of the epididymis. The length of the canal of the epididymis is, 
 in its natural condition, about three inches, but when unravelled 
 
 * The larger estimate is that by Krause; the smaller that by Berres. 
 f The coni vasculosi are about ^ of an inch in diameter, and about six to eight 
 lines long ; when unravelled they attain a length of six to eight inches. 
 
670 DISSECTION OF THE TESTIS. 
 
 it is nearly twenty feet in length. The diameter of the canal at its 
 commencement is about -fo of an inch ; at the globus minor about 
 JL of an inch, after which it again increases in diameter. It is 
 lined with columnar ciliated epithelium. 
 
 The vas defer ens begins at the lower part of the 
 
 VAS DEFERENS 
 
 globus minor ; at first it is somewhat convoluted, 
 but as it ascends behind the epididymis, it becomes subsequently 
 straight, and joins the other component parts of the cord. After 
 passing through the inguinal canal, it enters the abdomen through 
 the internal ring. It then winds round the outer side of the 
 epigastric artery, and, after crossing over the external iliac artery 
 and vein, it enters the pelvis, curves round the side and lower 
 part of the bladder, and empties itself into the prostatic part of 
 the urethra, after running a course of about two feet. 
 
 In connection with the anterior aspect of the cord, just above 
 the epididymis, are two or three small masses of convoluted tubes, 
 which are known as the organ of Giraldes, or the parepididy- 
 mis. They are lined with squamous epithelium, and are probably 
 the remains of part of the Woolffian body. 
 
 The hydatids of Morgagni are one or two small pedun ciliated 
 bodies, situated between the globus major and the body of the 
 testis. They are formed by pouchings of the tunica vaginalis, 
 and are filled with blood-vessels bound together by connective 
 tissue.* 
 
 The vas aberrans is a small convoluted tubule, with a caecal 
 extremity, found between the epididymis and the cord, and com- 
 municating usually with the canal of the epididymis. It is about 
 an inch in length, but when frayed out varies from two to twelve 
 inches in length. It, like the organ of Giraldes, is connected with 
 a foetal structure, the Woolffian body. 
 
 SPERMATIC The spermatic cord is composed of the spermatic 
 
 CORD, vessels, nerves, and lymphatics ; of the vas 
 
 deferens, with the deferential artery (a branch of the superior 
 vesical) ; of the cremaster muscle, and the cremasteric artery, a 
 
 * The largest, which lies upon the top of the testis, is stated to be the vestige of 
 ]\Iiiller's duct. 
 
DISSECTION OF THE TESTIS. 671 
 
 branch of the deep epigastric. It begins at the internal ring, 
 traverses the inguinal canal, and extends to the testis, where its 
 component parts pass to their respective destinations. The 
 coverings of the cord have been described with the anatomy of the 
 parts of hernia (p. 369). 
 
 The course of the spermatic arteries and veins has been 
 described in the dissection of the abdomen/(p. 403). The artery 
 is remarkably tortuous as it descends along the cord ; it enters the 
 back part of the testicle, and breaks up into a number of fine 
 ramifications, which spread out on the inner surface of the tunica 
 albuginea. The spermatic veins leave the testis 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 varicocele. It is, however, 
 certain that the larger veins do contain valves. 
 
 The lymphatics of the testis pass through the lumbar glands ; 
 hence these glands, and not the inguinal, become affected in malig- 
 nant disease of the testis. 
 
 The nerves of the testicle are derived from the sympathetic. 
 They descend from the abdomen with the spermatic arteries, and 
 come from the aortic plexus, with a few filaments from the hypo- 
 gastric plexus, which surround the deferential artery (p. 442). 
 This accounts for the ready sympathy of the stomach and intestine 
 with the testicle, and for the constitutional effects of an injury to 
 it. 
 
 DESCENT OF The testicle is originally developed in the lumbar 
 
 THE TESTIS. region, immediately below the kidney, and 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 a fibrous cord, termed the gubernaculum testis * 
 proceeds to the bottom of the scrotum. There is no evidence to 
 
 * 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. 
 
672 DISSECTION OF THE TESTIS. 
 
 warrant the assumption that the gradual contraction of the 
 gubernaculum effects the descent of the testis. The organ begins 
 to descend from the lumbar region about the fifth month of foetal 
 life, reaches the internal 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 abdomen, and in the lower animals continues to do so 
 throughout life.* But in the human subject the canal of com- 
 munication soon begins to close. It closes at the upper extremity 
 first,-f- and the closure is generally complete in a child born at its 
 full time4 This provides against the occurrence of ruptures, to 
 which man, owing to his erect position, is more exposed than 
 animals. At the end of the first month after birth, the canal is 
 entirely obliterated from the internal ring to the testis. Some- 
 times, however, this obliteration fails, or is only partial ; hence 
 may arise congenital hernia, or hydrocele. The possible existence 
 of a communication between the tunica vaginalis and the peritoneal 
 cavity of the abdomen, is one reason among many why caution 
 should be observed in treating hydroceles in children with stimu- 
 lating injections. 
 
 * According to Professor Owen, the African orang outang (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 liga- 
 mentum teres in the hip-joint. 
 
 f The frequency of hernia in the funicular portion of the vaginal process of the 
 peritoneum hardly bears this out. 
 
 \ Camper has shown, that the canal on the right side is nearly always open at 
 birth, whereas that on the left is usually closed. This explains the greater frequency 
 of hernia on the right side in children under one year old. Thus out of 3,014 cases 
 of inguinal hernia seen at the City of London Truss Society under one year, 2,269 
 occurred on the right side, and 745 on the left; or in the proportion of 3 to 1. 
 
INDEX. 
 
 ABD 
 
 Abdomen, parts exposed on opening, 373 
 
 Abdominal aorta, relations of, 401 
 
 Achillis tendo, 550 
 
 Alimentary canal, length of, 377 
 
 Anser hypoglossi, 35 
 
 Antrum pylori, 489 
 
 Aorta, abdominal, 384, 401 
 
 arch of, 128 
 
 branches of, 385 
 
 descending thoracic, 141 
 
 parts within arch, 13d 
 
 relations of arch to sternum, 130 
 Aponeurosis, lumbar, 234, 313 
 
 of scalp, 2 
 
 temporal, 96 
 
 vertebral, 234 
 
 Apparatus ligamentosus colli, 249 
 Appendices epiploicae, 493 
 Appendix vermiformis, 375 
 Aqueduct of Sylvius, 612 
 Aqueductus cochleae, 657 
 
 fallopii, 15 
 
 Aqueous humour, 644 
 Arachnoid membrane of brain, 678 
 Arbor vitse, 616 
 
 of uterus, 471 
 Arch, crural, 357, 504 
 deep, 507 
 
 palmar, superficial, 300 
 Arches, palatine anterior, 202 
 Arciform fibres of medulla, 586 
 
 fibres of Eolando, 628 
 Arteria sacra media, 385, 404 
 ABTEEIBS 
 
 alar thoracic, 263 
 
 anastomotica magna of thigh, 523 
 of arm, 281 
 
 angular, 86 
 
 anterior auricular, 95 
 
 AET 
 
 AETHEIES (continued) 
 
 anterior peroneal, 558 
 
 tibial, 529 
 
 arteria sigmoidea, 390 
 articular of popliteal, 544, 552 
 auditory, 582 
 auricular anterior, 95 
 
 branch of occipital, 55 
 posterior, 3, 56 
 axillary, 263 
 axis, thoracic, 259 
 azygos, 552, 544 
 of the back, 244 
 basilar, 581, 582 
 bieipital, 267 
 
 brachial, course and relations, 278 
 brachio-cephalic, 130 
 bronchial, 151, 176 
 buccal, 101 
 
 of the bulb of urethra, 427 
 carotid, common, course of, 32 
 internal, 177, 580 
 
 at base of skull, 
 
 227 
 
 course of, 109 
 curves of, 16 
 left, common, 131 
 carpal of radial, anterior, 291 
 
 posterior, 292, 335 
 of ulnar, anterior, 293 
 posterior, 293 
 centralis modioli, 657 
 
 retinae, 214, 644 
 cerebellar, anterior, 582 
 inferior, 581 
 superior, 582 
 cerebral, anterior, 581 
 middle, 581 
 posterior, 581, 582 
 
 X X 
 
INDEX. 
 
 ART 
 
 ART 
 
 ARTERIES (continued) 
 
 cervical, ascending, 67 
 
 deep, 69 
 choroid, anterior, 581 
 
 posterior, 582 
 ciliary, 214 
 
 anterior, 215, 639 
 long, 215, 639 
 short, 215 
 
 circumflex anterior of arm, 267 
 posterior of arm, 266 
 circumflexa ilii, deep, 361, 367, 406 
 coccygeal, 541 
 coeliac axis, 385, 386 
 colic, middle, 391 
 
 right, 391 
 colica dextra, 390 
 media, 390 
 sinistra, 390, 392 
 comes nervi ischiatici, 539, 641 
 mediani, 296 
 phrenici, 121 
 
 common iliac, relations of, 404 
 communicating, anterior, 581 
 
 posterior, 581 
 coronaria ventriculi, 386 
 coronary, 163 
 
 inferior, 86 
 superior, 86 
 of corpus callosum, 581 
 cremasteric, 367 
 crico-thyroid, 54 
 cystic, 386 
 
 of the cms penis, 427 
 deep cervical, 244 
 deferential, 442 
 descending palatine, 102 
 digital of foot, 561 
 
 of great toe, 531 
 of hand, 300 
 
 dorsal of index finger, 335 
 of thumb, 335 
 of penis, 427 
 dorsalis hallucis, 531 
 linguae, 52 
 pedis, 531 
 scapulae, 265, 323 
 epigastric, 355 
 epigastric deep, 366 
 
 pubic branch of, 367 
 ethmoidal, anterior, 215 
 posterior, 215 
 
 external carotid, course of, 52 
 circumflex, 521 
 
 ARTERIES (continued?) 
 
 external iliac, relations of, 405 
 mammary, 265 
 pudic, 355 
 pudic, deep, 497 
 facial, 45, 85 
 femoral, 518 
 frontal, 3, 215 
 gastric, 386 
 gastro-duodenalis, 386 
 gastro-epiploica dextra, 386 
 
 sinistra, 386 
 gluteal, 441, 536 
 hsemorrhoidal, external, 417 
 inferior, 417 
 superior, 392 
 helicine of penis, 458 
 hepatic, 386 
 hyoid, inferior, 53 
 superior, 51 
 iliac, 440 
 iliac internal, 440 
 ileo-eolic, 391 
 ilio-lumbar, 440 
 inferior dental, 100 
 
 external articular, 552 
 internal articular, 552 
 infra-orbital, 93, 102 
 spinous, 68, 316 
 innominate, 130 
 intercostal, 148 
 
 anterior, 121, 149 
 collateral, 149 
 posterior, 149 
 superior, 68 
 internal circumflex, 521 
 
 mammary, 65, 68, 121 
 maxillary, 99 
 interosseous, anterior, 296 
 common, 293 
 dorsal of hand, 325 
 metatarsal, 531 
 palmar, 309 
 perforating of, 309 
 posterior, 333 
 recurrent, 333 
 intra-spinal, 244 
 ischiatic, 441, 540 
 labial inferior, 86 
 lachrymal, 214 
 laryngeal, superior, 53 
 lateral sacral, 441 
 lateralis nasi, 86 
 of ligamentum teres, 521, 525 
 
INDEX. 
 
 675 
 
 ART 
 
 ART 
 
 AETBKIES (continued) 
 lingual, 51 
 
 rule for finding, 52 
 lumbar, 385, 403 
 
 abdominal br. of, 403 
 dorsal branch of, 403 
 spinal branch of, 403 
 malleolar, 530 
 masseteric, 101 
 mastoid, 55 
 mediastinal, 121 
 
 posterior, 151 
 meningea media, 12 
 
 parva, 12, 100 
 meningeal anterior, 12 
 
 middle, 12, 100 
 posterior, 12, 55, 57, 581 
 mental, 94 
 
 mesenteric, inferior, 385, 390, 392 
 superior, 385, 390, 391 
 metatarsal, 531 
 middle haemorrhoidal, 442 
 meningeal, 100 
 sacral, 443 
 temporal, 95 
 vesical, 442 
 musculo-phrenic, 121 
 mylo-hyoid, 101 
 nasal, 102 
 
 branch of ophthalmic, 215 
 nutrient of femur, 522 
 of fibula, 556 
 of humerus 281 
 of tibia, 656 
 obturator, 442, 524 
 occipital, 3, 55, 244 
 
 auricular branch of, 55 
 cesophageal, 151 
 omentel, 388 
 ophthalmic, 214 
 ovarian, 475 
 palatine, ascending, 45, 108 
 
 of ascendi ng pharyngeal, 110 
 inferior, 45 
 
 palmar arch, deep, 309 
 palmaris profunda, 309 
 palpebral, inferior, 215 
 superior, 215 
 pancreatic, 386 
 pancreatica magna, 388 
 pancreatico-duodenal, inferior, 391 
 superior, 386, 
 
 391 
 pancreaticse parvse, 388 
 
 AETEEIES (contimicd) 
 
 perforating of intercostal, 121 
 plantar, 561 
 profunda, 521 
 peroneal, 556 
 
 pharyngeal, ascending, 56, 110 
 phrenic, 385, 402 
 plantar, external, 561 
 internal, 561 
 popliteal, 544, 551 
 posterior circumflex, 320 
 scapular, 316 
 tibial, 555 
 princeps cervicis, 55, 244 
 
 pollicis, 308 
 profunda femoris, 520 
 inferior, 281 
 superior, 279 
 pterygo-palatlne, 102 
 pterygoid, 101 
 pudic, 425, 442, 541 
 pulmonary, 151 
 pyloric, 386 
 radial, 290 
 
 recurrent, 291 
 in palm, 308 
 radialis indicis, 309 
 recurrent tibial, 530 
 renal, 385, 402 
 sacra media, 443, 385 
 scapular, posterior, 68 
 of septum, 102 
 sigmoidea, 392 
 spermatic, 385, 403 
 spheno-palatine, 102 
 spinal, anterior, 581, 625 
 lateral, 66 
 posterior, 581, 625 
 splenic, 386, 387 
 sterno-mastoid, inferior, 68 
 middle, 54 
 superior, 55 
 stylo-mastoid, 56, 652 
 subclavian, branches of, 65 
 course of, 60 
 left, 62, 131 
 
 sublingual, course of, 52 
 submental, 45 
 subscapular, 265 
 superficial circumflexa ilii, 496 
 epigastric, 496 
 external pudic, 496 
 perineal, 418 
 superficialis colli, 68, 313, 316 
 
 x x 2 
 
676 
 
 INDEX. 
 
 ART 
 
 BUR 
 
 ARTERIES (continued) 
 
 superficialis volse. 291 
 superior dental, 102 
 
 epigastric, 121 
 external articular, 552 
 hsemorrhoidal, 390 
 intercostal, 65 
 internal articular, 552 
 profunda, 324 
 thyroid, 58 
 vesical, 441 
 
 supra-aoromial, 68, 315 
 orbital, 3, 214 
 renal, 385, 402 
 scapular, 67, 315, 323 
 sural, 544, 553 
 tarsal, 631 
 
 temporal anterior, 95 
 deep, 101 
 
 anterior, 101 
 posterior, 95, 101 
 superficial, 8, 94 
 thoracica acromialis, 259 
 alaris, 263 
 humeraria, 259 
 inferior or long, 265 
 superior or short, 259 
 thymic, 121 
 thyroid axis, 65, 67 
 inferior, 67 
 tonsillar, 45 
 transversalis colli, 68 
 
 faciei, 87. 95 
 humeri, 67, 315 
 
 transverse communicating of ankle, 
 556 
 
 perineal, 418 
 tympanic of internal carotid, 228 
 
 maxillary, 100 
 ulnar, 292 
 
 palmar recurrent of, 300 
 recurrent anterior, 293 
 posterior, 293 
 ulnaris profunda, 300 
 uterine, 468 
 vaginal, 468 
 vasa brevia, 384, 386 
 
 intestini tenuis, 391 
 vertebral, 65, 66, 581 
 vesical, inferior, 442 
 middle, 442 
 superior, 441 
 vidian, 102 
 Aryteno-epiglottic folds, 193 
 
 Arytenoid cartilages, 192 
 Auricle, left, 161 
 
 right, 156 
 Auriculo ventricular opening, left, 162 
 
 right, 159 
 Axilla, boundaries of, 262 
 
 contents of, 261 
 
 dissection of, 261 
 
 fascia of, 261 
 
 glands of, 263 
 
 BACK 
 
 cutaneous nerves of, 310 
 
 muscles of, 234, 310 
 Bile-duct, 889 
 Bladder, female, 465 
 
 gall, 480 
 
 ligaments, false, of, 429 
 
 lymphatics of, 449 
 
 peritoneal covering of, 412 
 
 positions of, 413 
 
 urinary, blood-vessels of, 449 
 
 urinary, position of, 435 
 structure of, 446 
 uvula of, 448 
 Bodies, olivary, 585 
 
 restiform, 586, 627 
 Body, vitreous, 644 
 BRAIN 
 
 arteries of, 380 
 
 convolutions of, 592 
 
 dissection of, 578 
 
 fissures of, 589 
 
 general description of, 583 
 
 membranes of, 578 
 
 peculiarities of circulation in, 583 
 Bronchus, left, 170 
 
 right, 170 
 
 Burn's falciform, process of, 502 
 Bursse, biceps, near tendon of, 346, 276 
 
 of carpus, 305 
 
 over knuckles, 325 
 
 over olecranon, 325 
 
 over patella, 517 
 
 under coraco-acromial ligament, 
 341 
 
 under coraco-brachialis, 277 
 
 under deltoid, 320 
 
 under gastrocnemius, 649 
 
 under gluteus maximus, 535 
 medius, 535 
 
 under gracilis, 512 
 
 under latissimus dorsi, 312 
 
INDEX. 
 
 677 
 
 BUB 
 
 Bursse, under ligamentum patellae, 51 7 
 under obturator internus, 537 
 under popliteus, 553 
 under Sartorius, 510 
 under semi-membranosus, 546 
 under subseapularis, 322 
 under teres major, 322 
 under triceps, 324 
 under tuberosity of Ischium, 533 
 
 Caecum, 375 
 
 meso-caecum, 375 
 Canal of Bowman, 635 
 
 crural, 507 
 
 of epididymis, 669 
 
 of Huguier, 227, 650 
 
 of Hunter, 519 
 
 inguinal, 366 
 
 of Petit, 646 
 
 of Recklinhausen, 635 
 
 of Schlemm, 635 
 
 of Stilling, 645 
 
 for tensor tympani, 651 
 Canaliculus of eyelid, 80 
 Canals of cervix uteri, 471 
 
 reunions, 658 
 
 semicircular, 655 
 
 spiralis modioli, 657 
 Capsule, Glisson's, 477 
 Caput coli, 375 
 
 gallinaginis, 450 
 Cartilages, tarsal, 80 
 Caruncula lachrymalis, 78 
 Carunculse myrtiformes, 462 
 Cauda equina, 621, 625 
 Central canal of spinal cord, 623 
 
 tendon of Perineum, 418 
 Cerebellum, 613 
 
 amygdalae of, 615 
 
 fissure of, great horizontal, 613 
 
 flocculus of, 615 
 
 lateral hemispheres of, 613 
 
 lobes of, 614, 616 
 
 peduncles of inferior, 616 
 middle, 616 
 superior, 611, 616 
 
 vermiform process of, 613 
 
 uvula of, 615 
 Cerebrum, 588 
 
 Chambers of eye, anterior, 638 
 posterior, 638 
 Chordae Willisii, 9 
 Chordae tendineae, 158 
 
 COR 
 
 Choroid coat of the eye, 636 
 
 plexus, 607 
 
 of the fourth ventricle, 612 
 
 plexuses, 579 
 Cilia, 78 
 Ciliary muscle, 636, 638 
 
 processes, 636 
 Circle of Willis, 582 
 Clitoris, 459 
 Cochlea, 656 
 Cceliac axis, 386 
 Colon, ascending, 375, 383 
 
 commencement of, 375 
 
 descending, 375, 383 
 
 hepatic flexure of, 375 
 
 sigmoid flexure of, 376 
 
 splenic flexure of, 376 
 
 transverse, 375, 383 
 
 transverse meso-eolon, 380, 383 
 Columnae corneae, 158 
 Columns, anterior of medulla, 626 
 
 lateral of medulla, 627 
 Commissure, great transverse, 600 
 
 anterior, 609 
 
 middle, 609 
 
 optic, 596 
 
 posterior, 610 
 
 of spinal cord, 622 
 Coni vasculosi testis, 669 
 Conjunctiva oculi, 631 
 Convolution, frontal, 592 
 
 occipital, 592 
 
 parietal, 592 
 
 temporo-sphenoidal, 592 
 
 uncinate or hippocampal, 593 
 Cord spermatic, 670 
 Cornea, 634 
 
 Corneal tubes of Bowman, 635 
 Cornicula laryngis, 190 
 Corniculum laryngis, 192 
 Corpora albicantia, 594 
 
 mammellaria, 594 
 
 quadrigemina, 611 
 Corpus Arantii, 160 
 
 callosum, 589, 600 
 
 cavernosum penis, 456 
 
 dentatum, 586, 616 
 
 fimbriatum, 606 
 
 geniculatum externum, 609 
 internum, 609 
 
 Highmorianum, 668 
 
 luteum, 475 
 
 spongiosum penis, 456 
 
 striatum, 606 
 
678 
 
 INDEX. 
 
 COR 
 
 Corti, organ of, 661 
 
 rods of, 661 
 
 Cotunnii liquor or peri-lymph, 658 
 Cowper's glands, 425, 452 
 Cricoid cartilage, 191 
 Cricothyroid membrane, 191 
 Crista vestibuli, 655 
 Crura cerebri, structure of, 628 
 Crural arch, 504 
 canal, 507 
 Cms clitoridis, 459 
 
 penis, 456 
 
 Crystalline lens, 646 
 Cuneiform cartilages, 192 
 Cnneus, 593 
 Cupola, 657 
 
 Dartos scroti, 665 
 
 tunica, 417 
 
 Deglutition, mechanism of, 188 
 Descemet, membrane of, 635 
 DIAPHRAGM, 395 
 
 aortic opening of, 396 
 
 central tendon of, 396 
 
 functions of, 397 
 
 nerves of, 397 
 
 cesophageal opening of, 397 
 
 openings of, 396 
 
 vena cava, opening of, 397 
 Diogenes, cup of, 297 
 Discus proligerus, 475 
 DISSECTION 
 
 of the eye, 631 
 
 of male perineum, 414 
 
 of the organ of hearing, 648 
 
 of spinal cord, 617 
 
 of upper arm, 27 1 
 Duct, nasal, 231 
 
 thoracic, 142 
 DUCTS, 
 
 bile, 389 
 
 cystic, 480 
 
 galactophorus, 664 
 
 of parotid gla ;d, 89 
 
 of prostate, 451 
 
 of Rivinus, 50 
 
 of sublingual gland, 50 
 
 of submaxillary gland, 44 
 
 Wharton's, 44 
 
 DtJCTUS 
 
 anteriosus, 152, 168 
 
 cochlearis, 660 
 
 communis choledochus, 389, 480 
 
 FAS 
 
 DUCTUS (continued) 
 
 communis ejaculatorius, 437 
 
 venosus, 168, 169 
 Duodenum, course of, 374 
 
 relations of, 392 
 Dura mater, 6 
 
 sinuses of, 8 
 
 Ear, muscles of, 2 
 Elbow, triangle at bend of, 287 
 Endocardium, 165 
 Endolymph, 659 
 EPIDIDYMIS, 666 
 
 globus major, 666 
 minor, 666 
 Epiglottis, 192 
 
 cushion of, 195 
 Eustachian tube, 186 
 Eyelids, structure of, 79 
 
 Face, dissection of, 73 
 
 Fallopian tube, 464 
 tubes, 473 
 
 fimbrise of, 473 
 
 Falx cerebri, 7 
 cerebelli, 7 
 
 FASCIA 
 
 cervical, deep, 21 
 iliaca, 399 
 of the leg, 526 
 lumbar, 235 
 perineal deep, 417 
 superficial, 417 
 plantar, 557 
 praevertebral, 22 
 propria of hernia, 507 
 
 FASCIAE 
 
 anal, 431 
 of the arm, 275 
 of the fore-arm, 286 
 on back of forearm, 286 
 buccal, 85 
 cremasteric, 361 
 cribriform, 496, 501 
 falciform of Burns, 502 
 infundibuliform, 366 
 intercolumnar, 359 
 lata of thigh, 500 
 of metacarpus, 327 
 obturator, 431 
 palmar, 297 
 pelvic, 430 
 
INDEX. 
 
 679 
 
 FAS 
 
 FASCIA (continued) 
 
 pelvic, in female, 465 
 
 recto-vesical, 431 
 
 semi-lunar of biceps, 276 
 
 spermatic, 359 
 
 superficial of abdomen, 354 
 thigh, 496 
 
 transversalis, 364 
 Fasciculi teretes, 627 
 Faucium isthmus, 183 
 Fenestra ovalis, 651 
 
 rotunda, 651 
 
 Ferrein, pyramids of, 485 
 Fibro-cartilages, between radius and ulna, 
 347 
 
 interarticular of jaw, 253 
 
 of clavicle, 339 
 
 inter-vertebral, 247 
 Fimbriae of the ovary, 464 
 Fissura palpebrarum, 78 
 Fissures, calcarine of brain, 591 
 
 calloso-marginal of brain, 591 
 
 of Bichat, 606 
 
 central of brain, 589, 590 
 
 great transverse, 606 
 
 longitudinal of brain, 588 
 
 nerves in sphenoidal, 16 
 
 parieto-occipital of brain, 589, 591 
 
 primary of brain, 589 
 
 of Sylvius, 588, 590 
 Flexor tendons in palm, sheaths of, 303 
 Foetal circulation, 168 
 Folds, aryteno- epiglottic, 193 
 
 glosso-epiglottic, 193, 194 
 Foramen chordae anterius, 654 
 posterius, 654 
 
 caecum of medulla, 584 
 
 of Monro, 606 
 
 quadratum, 397 
 
 of Winslow, 381 
 Foramina, ovale of heart, 157, 162 
 
 of Thebesius, 158 
 Fornix, 605 
 
 Fossa uavicularis of urethra, 454 
 Fossae, ischio- rectal, 415, 428 
 Fovea hemispherica, 655 
 
 hemi-elliptica, 655 
 
 centralis, 640 
 Frsenum preputii, 455 
 
 Galen, rete mirabile of, 532 
 
 veins of, 608 
 Gall bladder, 480 
 
 GLA 
 
 Gall bladder, situation of, 377 
 Ganglia, abdominal of sympathetic, 407 
 
 cervical, inferior, 117 
 middle, 116 
 superior, 115 
 
 semi-lunar, 385, 395, 407 
 
 of spinal nerves, 624 
 
 sympathetic of neck, 115 
 
 thoracic of sympathetic, 147 
 Ganglion diaphragmaticum, 397 
 
 Gasserian. 13 
 
 impar, 114, 445 
 
 jugular, 224 
 
 of glosso-pharyngeal, 109 
 
 lenticular, 215 
 
 ophthalmic, 215 
 
 otic, 222 
 
 petrous, 224 
 
 of glosso-pharyngeal, 109 
 
 of pneumogastric of root, 111 
 of trunk, 112 
 
 of Eibes, 114 
 
 of root of pneumogastric, 225 
 
 spheno-palatine, 220 
 
 submaxillary, 51, 107 
 Gimbernat's ligament, 50* 
 GLANDS anal, 415 
 
 agminate, 492 
 
 axill iry, 263 
 
 of Bartholin, 463 
 
 of Brunner, 492 
 
 buccal, 85 
 
 Cowper's, 425-, 452 
 
 deep cervical lymphatic, 38 
 
 of Duverney, 463 
 
 lachrymal, 209 
 
 of Lieberkiihn, 492 
 
 lymphatic, of elbow, 275 
 
 superficial of neck, 20 
 inguinal, 355 
 
 Meibomian, 81 
 
 mesenteric, 390 
 
 molar, 85 
 
 oasophageal, 145 
 
 of Pacchioni, 9 
 
 palatine, 187 
 
 parotid, relations of, 88 
 
 peptic, 490 
 
 of Peyer, 492 
 
 popliteal, 544 
 
 prostate, 438 
 
 pyloric, 490 
 
 salivary sublingual, 50 
 
 solitary, 493 
 
680 
 
 INDEX. 
 
 GLA 
 
 GLANDS (continued) 
 
 submaxillary, 43 
 
 lymphatic, 45 
 
 superficial inguinal, 496 
 
 tracheal, 171 
 
 Glandula socia parotidis, 88 
 Glandulse concatenate, 39 
 
 Pacchioni, 9 
 Glans clitoridis, 460 
 Glisson's capsule, 389, 477 
 Glosso-epiglottic folds, 193 
 
 pharyngeal nerre, 598 
 Glottidis rima, 194 
 Graafian resides, 475 
 Gubernaculum testis, 671 
 Gyrus fornicatus, 593 
 
 Hamstring muscles, 545 
 Hamulus of cochlea, 657 
 Heart, attachment of large arteries to, 1 65 
 
 dissection of, 155 
 
 fibrous skeleton of, 164 
 
 form and position of, 134, 137 
 
 nerves of, 152 
 
 peculiarities of feetal, 167 
 
 position and form of, 134 
 
 thickness of its cavities, 166 
 Heart valves, position of, 138 
 Helicotrema, 657 
 
 Henle, looped tubes of, in kidney, 486 
 Hernia, congenital, 370 
 
 direct inguinal, 369 
 
 encysted, 371 
 
 funicular, 371 
 
 femoral, anatomy of parts concerned, 
 503 
 
 coverings of, 508 
 
 seat of stricture in, 509 
 
 division of stricture in, 509 
 
 infantile, 371 
 
 inguinal, direct, 369 
 
 oblique inguinal, 368 
 
 position of spermatic cord in, 371 
 
 seat of stricture in, 371 
 Herophili torcular, 11 
 Hessel bach's triangle, 369 
 Hey's ligament, 503 
 Hippocampus major, 604, 607 
 minor, 603, 607 
 Houston, valves of, 495 
 Huguier, canal of, 650 
 Humour, aqueous, 644 
 vitreous, 644 
 
 J01 
 
 Hunter's canal, 519 
 Hyaloid membrane, 644 
 Hydatids of Morgagni, 671 
 Hymen, 462 
 Hypoglossal nerve, 599 
 
 Ileo-csecal valve, 495 
 
 Ileum, 374 
 
 Incus, 652 
 
 Infundibulnm of right ventricle, 159 
 
 Interarticular fibro-cartilage of knee, 570 
 
 Internal ear, 654 
 
 Intestine, large, 375 
 
 external characters of, 493 
 small, 374 
 
 glands of, 492 
 lymphatics of, 493 
 nerves of, 493 
 structure of, 490 
 Iris, 638 
 
 arteries of, 639 
 muscular fibres of, 639 
 nerves of, 639 
 Ischio- rectal fossa, 428 
 Iter a tertio ad quartum ventriculam, 
 609, 612 
 
 Jacob's membrane, 643 
 Jejunum, 374 
 Joints, ankle, 572 r 
 
 between atlas and axis, 250 
 
 of carpns, 348 
 
 costo-sternal, 252 
 
 crico-arytenoid, 192 
 thyroid, 201 
 
 elbow, 343 
 
 of the fingers, 351 
 
 of the foot, 574 
 
 hip, 566 
 
 intr-rcarpal, 349 
 
 knee, 568 
 
 carpo-metacarpal, 350 
 
 lower jaw, 252 
 
 occipito-atlantoid, 249 
 
 radio-carpal of wrist, 346 
 
 radio-ulnar, inferior, 346 
 superior, 345 
 ribs of the, 251 
 
 scapulo-clavicular, 340 
 
 shoulder, 341 
 
 sterno-clavieular, 338 
 
 tarsal, 5H 
 
INDEX. 
 
 681 
 
 JOI 
 
 Joints, tarso-metatarsal, 576 
 of the thumb, 349 
 tibio-fibular, superior, 572 
 inferior, 572 
 of the toes, 577 
 wrist, synovial membrane of, 351 
 
 Kidneys, relations of, 394 
 situation of, 378 
 structure of, 483 
 
 Labia majora, 459 
 
 minora, 459, 460 
 Labyrinth of internal ear, 654 
 Lachrymal gland, 209 
 
 sac, 231 
 
 Lacunae of urethra, 454 
 Lamina cinerea, 594 
 cribrosa, 633 
 fusca, 633 
 
 spiralis of cochlea, 657 
 Lancisi, nerves of, 601 
 Laryngotomy, 40 
 Larynx, cartilages of, 189 
 dissection of, 189 
 mucous membrane of, 193 
 muscles of, 197 
 nerves of, 200 
 opening of inferior, 194 
 superior, 194 
 sacculus of, 195, 196 
 ventricle of, 195, 196 
 vessels of, 199 
 
 Lawrence, on femoral hernia, 507 
 Lens, crystalline, 646 
 LIGAMENTS, alaria, 570 
 of ankle anterior, 573 
 posterior, 573 
 
 annular anterior of ankle, 527 
 external do., 527 
 internal do., 527 
 of carpus anterior, 301 
 of radius, 345 
 posterior of wrist, 326 
 anterior of carpus, 348 
 elbow, 345 
 wrist, 346 
 
 astragalo-calcaneal, 574 
 scaphoid, 574 
 
 atlanto-axoid anterior, 250 
 posterior, 250 
 broad tarsal, 80 
 
 LIG 
 
 LIGAMENTS (continued?) 
 broad of uterus, 463 
 calcaneo-cuboid inferior, 575 
 superior, 575 
 scaphoid, 575 
 
 of carpus lateral external, 348 
 internal, 348 
 interosseous, 348 
 conoid, 340 
 coraco-acromial, 341 
 clavicular, 340 
 humeral or accessory, 342 
 coronary of knee, 571 
 costo-clavicular or rhomboid, 339 
 sternal, 252 
 transverse anterior, 251 
 middle, 251 
 posterior, 251 
 vertebral or stellate, 251 
 cotyloid, 568 
 crico-thyroid, 191 
 crucial, 570 
 denticulate, 620 
 external, 575 
 
 lateral of elbow, 344 
 of jaw, 252 
 of wrist, 346 
 tarsal, 80 
 
 glenoid of shoulder, 343 
 glosso-epiglottic, 202 
 great sacro-ischiatic, 566 
 Gimbernat's, 359, 504 
 Hey's, 503 
 of hip joint, 566 
 hyo-epiglottic, 193 
 ilio-femoral, 568 
 lumbar, 565 
 
 interarticular of rib, 251 
 intercarpal, 349 
 inter-clavicular, 338 
 internal lateral of elbow, 344 
 annular of ankle, 555 
 lateral of jaw, 252 
 of wrist, 346 
 
 interosseous of fore-arm, 345 
 of leg, 572 
 of metacarpus, 350 
 of tarsus, 576 
 interspinous, 246 
 of jaw, internal lateral, 107 
 of knee joint, 568 
 lateral of ankle, external, 572 
 internal, 572 
 external of knee, 569 
 
682 
 
 INDEX. 
 
 LIG 
 
 LIGAMENTS (continued) 
 
 lateral internal of knee, 569 
 latum pulmonis, 139 
 lesser sacro-ischiatic, 566 
 of the liver, 377, 477 
 mucosum of knee, 570 
 nuchae, 234, 248, 311 
 occipito-atlantoid anterior, 249 
 
 posterior, 249 
 axoid, 249 
 
 oblique of radius, 345 
 odontoid or check, 249 
 orbicular of radius, 345 
 of the ovary, 463, 474 
 pa 1 mar of fingers, 304, 352 
 palpebral, 80 
 of patella, 516 
 of the pelvis, 564 
 plantse breve, 575 
 
 longum, 575 
 
 posticum Winslowii, 546, 569 
 posterior of carpus, 348 
 of elbow, 345 
 of wrist, 346 
 Poupart's, 357, 504 
 pterygo-maxillary, 84, 180 
 pubic anterior, 365 
 posterior, 365 
 round of uterus, 464 
 sacro-iliac, anterior, 565 
 
 interosseous, 566 
 oblique, 566 
 posterior, 565 
 ischiatic, great, 566 
 
 less, 566 
 spinal anterior common, 246 
 
 posterior common, 246 
 of the spine, 246 
 stellate, 251 
 
 sterno-clavicular anterior, 338 
 posterior, 338 
 stylo-hyoid, 108 
 stylomaxillary, 23, 46 
 snbflava, 246 
 sub-pubic, 365 
 supra-spinous, 246 
 suspensorium penis, 456 
 teres, 567 
 
 of liver, 372 
 thyro-epiglottic, 193 
 
 hyoid anterior, 1 90 
 
 lateral, 190 
 
 tibio-fibular anterior, 571 
 posterior, 571 
 
 LYM 
 
 LIGAMENTS (continued) 
 
 transverse of atlas, 250 
 fingers, 298 
 knee, 571 
 metacarpal, 336 
 metatarsal, 577 
 
 trapezoid, 340 
 
 triangular of urethra, 417, 422, 424 
 
 of tympanic bones, 653 
 
 Winslowii posticum, 569 
 
 LlGAMENTUM 
 
 arcuritum extern um, 396 
 internum, 396 
 
 spirale, 661 
 
 suspensorium, 250 
 
 Ligature of external iliac artery, 406 
 LINEA 
 
 alba, 357, 363 
 
 semi-lunaris, 363 
 
 splendens, 620 
 
 transversa, 362 
 
 Listen, ligature of external iliac, 497 
 Lithotomy, 415 
 
 parts divided in, 424 
 LIVEB 
 
 description of, 475 
 
 fissures of, 476 
 
 functions of, 480 
 
 ligaments of, 377, 477 
 
 lobes of, 476 
 
 lobules of, 478 
 
 lymphatics of, 480 
 
 nerves of, 480 
 
 position, 377 
 
 Lobes of brain, central, 591 
 frontal, 591 
 parietal, 591 
 occipital, 591 
 temporo-sphenoidal, 591 
 Lobulus Spigelii, 476 
 Locus niger, 629 
 
 perforatus anticus, 594 
 posticus, 594 
 Lower, tubercle of, 158 
 Lung, constituents of root, 153 
 Lungs, lobules of, 174 
 
 lymphatics of, 176 
 
 nerves of, 176 
 
 position of, 124 
 
 position and form of, 140 
 
 structure of, 169, 172 
 Lymphatic glands, bronchial, 152 
 
 intercostal, 151 
 Lymphatics in lumbar region, 401 
 
INDEX. 
 
 683 
 
 LTM 
 
 Lymphatics of small intestine, 493 
 
 oftestis, 671 
 Lyra, 6C6 
 
 Macula lutea, 640 
 
 Malleus, 652 
 
 Malpighi, capsules of, 484 
 
 pyramids of, 484 
 Malpighian, corpuscles of spleen, 
 
 482 
 Mammary gland, 663 
 
 arteries of, 664 
 
 lymphatics of, 664 
 
 structure of, 663 
 Mammilla, 664 
 Masticntion, muscles of, 94 
 Meatus auditorius externus, 649 
 
 urinarius, female, 460 
 MEDIASTINUM 
 
 anterior, 122 
 
 middle, 122 
 
 posterior, 122, 141 
 
 testis, 668 
 Medulla oblongata, 583 
 
 minute structure of, 626 
 Membrana pupillaris, 640 
 
 tectoria, 661 
 
 tympani, 651 
 
 arteries of, 652 
 Membrane, basilar, 660 
 
 costo-coracoid, 258 
 
 hyaloid, 644 
 
 of Reissner, 660 
 Membraneous labyrinth, 657 
 
 semicircular canals, 658 
 Mesentery, 382 
 Mesorchium, 672 
 Modiolus of cochlea, 657 
 Monro, foramen of, 606 
 Morgagni, hydatids of, 671 
 
 sinus of, 180 
 
 Miiller, fibres of, 642 
 MUSCLES 
 
 abdominal, functions of, 363 
 nerves of, 364 
 
 abductor indicis, 337 
 
 minimi digit! manus, 307 
 
 pedis, 558 
 pollicis manus, 306 
 pedis, 585 
 
 accelerator urinse, 420 
 
 accessorius ad sacro-lumbalem, 236 
 flexor, 560 
 
 MUS 
 
 MUSCLES (continued) 
 
 adductor brevis femoris, 513 
 longus, 512 
 
 magnus, 514 
 pollicis manus, 307 
 
 pedis, 562 
 anconeus, 330 
 aryteno-epiglottideus, 198 
 arytenoideus, 198 
 attoilens aurem, 2 
 attrahens aurem, 2 
 azygos uvulae, 184, 185 
 biceps of arm, 276 
 brachialis anticus, 278 
 buccinator, 83 
 cervicalis ascendens, 236 
 ciliaris, 77 
 ciliary, 636, 638 
 coccygeus, 439 
 cochlearis, 661 
 complexus, 238 
 compressor naris, 82 
 
 sacculi laryngis, 196 
 urethrae, 425 
 
 in the female, 461 
 coraco- brachialis, 277 
 corrugator supercilii, 77 
 creenaster, 361 
 
 crico-arytenoideus lateralis, 198 
 posticus; 197 
 crico-thyroideus, 197 
 crurseus, 516 
 deltoid, 318 
 depressor alse nasi, 82 
 
 anguli oris, 75 
 labii inferioris, 75 
 digastricus, 41 
 dilatator iridis, 639 
 
 naris anterior, 82 
 posterior. 82 
 ejaculator urinae 42 ) 
 erector clitoridis, 459 
 penis, 420 
 spinae, 236 
 
 external sphincter ani, 416 
 extensor brevis digitorum, 530 
 
 carpi radialis brevior, 328 
 longior, 328 
 carpi ulnaris, 330 
 communis digitorum, 329 
 indicis, 332 
 longus digitorum, 628 
 minimi digiti, 330 
 ossis met. pollicis, 331 
 
684 
 
 INDEX. 
 
 MUS 
 
 MUSCXKS (continued) 
 
 extensor primi internodiipollicis,331 
 secundi internodii pollicis, 
 
 332 
 
 proprius pollicis, 529 
 flexor accessorius, 560 
 
 brevis digitorum, 559 
 
 minimi digiti manus,308 
 pedis, 563 
 pollicis manus, 307 
 
 pedis, 562 
 carpi radialis, 288 
 ulnaris, 288 
 flexor cruris, 545 
 
 longus digitorum, 554 
 pollicia, 554 
 
 manus, 295,305 
 profundus digitorum, 295 
 gastrocnemius, 549 
 gemellus inferior, 537 
 superior, 537 
 genio-hyoglossus, "48 
 
 hyoideus, 47 
 gluteus maximus, 534 
 medius, 535 
 minimus, 535 
 gracilis, 512 
 hyoglossus, 47 
 iliacus, 399 
 
 inferior constrictor of pharynx, 178 
 infra-spinatus, 321 
 intercostal, 148 
 interosseous of foot, 563 
 
 of hand, 336 
 interspinales, 240 
 intertransversales, 240 
 ischio-cavernous, 421 
 latissimus dorsi, 270, 312 
 laxator tympani, 653 
 levator anguli oris, 83 
 
 scapulae, 314 
 ani, 439 
 
 female, 465 
 labii inferioris, 75 
 
 superioris alaeque nasi, 
 83 
 
 proprius, 83 
 menti, 75 
 palati, 185 
 palpebrse, 79, 210 
 prostatse, 439 
 levatores costarum, 240 
 linguales, inferior, 205 
 superior, 205 
 
 MUS 
 
 MUSCLES (continued) 
 
 longissimus dorsi, 236 
 longus colli, 245 
 lumbricales, manus, 306 
 
 pedis, 560 
 masseter, 96 
 of mastication, 94 
 
 middle constrictor of pharynx, 179 
 mucosse, 491 
 multifidus spinse, 239 
 muscularis mucosse, 491 
 mylo-hyoideus, 46 
 obliquus externus abdominis, 357 
 inferior, 216 
 
 capitis, 241 
 
 internus abdominis, 359 
 superior, 211 
 
 capitis, 241 
 
 obturator externus, 538 
 internus, 537 
 occipito-frontalis, 2 
 opgonens digiti minoris, 308 
 
 pollicis, 307 
 orbicularis oris, 74 
 
 palpebrarum, 76 
 omo-hyoid, 29, 315 
 palato-glossus, 184, 185 
 pharyngeus, 185 
 palmaris brevis, 297 
 pectineus, 513 
 pectoralis major, 256 
 minor, 263 
 perineus brevis, 532 
 
 longus, 531, 564 
 tertius, 528 
 plantaris, 550 
 platysma myoides, 17 
 palmaris longus, 288 
 popliteus, 553 
 prsevertebral, 244 
 pronator quadratus, 296 
 radii teres, 288 
 psoas magnus, 398 
 parvus, 399 
 
 pterygoidtus externus, 98 
 internus, 99 
 pyramidalis, 363 
 
 nasi, 2, 82 
 pyriformis, 537 
 quadratus femoris, 537 
 
 lumborum, 400 
 quadriceps femoris, 515 
 recti of the eye, 211 
 rectus abdominis, 362 
 
INDEX. 
 
 685 
 
 MUS 
 
 MUSCLES (continued) 
 
 rectus capitis anticus major, 245 
 minor, 245 
 lateralis, 242 
 posticus major, 240 
 minor, 240 
 externus oculi, 211 
 femoris, 515 
 internus oculi, 211 
 inferior oculi, 211 
 superior oculi, 211 
 retrahens aurem, 3 
 risorius, 17, 74 
 rotatores spinae, 239 
 rhomboideus major, 314 
 minor, 314 
 sacro-lumbalis, 236 
 Sartorius, 510 
 scalenus anticus, 58 
 medius, 58 
 posticus, 58 
 semi-membranosus, 546 
 semi-spinalis colli, 239 
 dorsi, 239 
 
 semi-tendinosus, 546 
 Berratus magnus, 270, 316 
 
 posticus inferior, 234 
 superior, 234 
 soleus, 550 
 
 sphincter ani internus, 494 
 iridis, 639 
 vaginae, 462 
 vesicae, 446 
 spinalis dorsi, 238 
 splenius capitis, 235 
 
 colli, 235 
 stapedius, 654 
 sterno-cleido-mastoideus, '24 
 hyoid, 29 
 thyroid, 29 
 stylo-glossus, 49, 107 
 hyoideus, 43 
 pharyngeus, 108 
 eubanconeus, 324 
 subclavius, 258 
 subcrurseus, 516 
 Bublimis digitorum, 289 
 subscapularis, 270, 322 
 superior constrictor of pharynx, 180 
 supinator radii brevis, 332 
 longus, 29 
 supra-spinatus, 322 
 temporal, 97 
 tensor fasciae femoris, 514 
 
 NER 
 
 MUSCLES (continued) 
 tensor palati, 185 
 tarsi, 217 
 tympani, 653 
 teres major, 270, 322 
 
 minor, 321 
 thyro-arytenoideus, 199 
 
 hyoid, 31 
 tibialis anticus, 527 
 
 posticus, 554, 564 
 trachelo-mastoid, 237 
 trans versalis abdominis, 361 
 colli, 237 
 pedis, 563 
 
 transverso-spinalis, 238 
 transversus perinei, 421 
 
 deep, 422 
 trapezius, 311 
 triangularis sterni, 120 
 triceps extensor cubiti, 284, 323 
 
 femorie, 515 
 of ureters, 449 
 vastus externus, 516 
 internus, 516 
 zygomaticus major, 76 
 minor, 76 
 
 Musculi papillares, 158 
 pectinati, 156, 161 
 
 Nabothi ovula, 471 
 
 Nasal fossae, posterior openings, 182 
 
 Neck, central line of, 39 
 
 dissection of, 17 
 NEBVES 
 
 abducens oculi, 15 
 accessory obturator, 410 
 anterior crural, 410, 523 
 
 cutaneous of abdomen, 356 
 tibial, 532 
 auditory, 15 
 auriculo-parotidean, 20 
 
 temporal, 5, 95, 165 
 auricular branch of pneumogastric, 
 112, 225 
 
 posterior, 56 
 axillary, plexus of, 267 
 back, cutaneous of, 310 
 buccal branch of facial, 92 
 
 of inferior maxillary, 104 
 calcaneo-plantar, 557 
 cardiac branch of pneumogastric, 113, 
 146 
 
 inferior, 117 
 
686 
 
 INDEX. 
 
 NER 
 
 NERVES (continued) 
 
 cardiac middle, 116 
 superior, 116 
 
 carotid of glosso-pharyngeal, 109 
 cervical, acromial branch of, 21 
 clavicular, branch of, 21 
 first, 228 
 second, 228 
 sternal, branch of, 21 
 superficial, 21 
 cervico-facial, 91 
 chorda tympani, 107, 227, 654 
 ciliary, 640 
 
 long, 213 
 
 circumflex, 269, 320 
 coccygeal, 244, 444 
 communicans Peronei, 542 
 commnnicans noni, 35, 57 
 cranial, exit of, 1 2 
 
 at base of skull, 224 
 crural branch of genito-crural, 
 
 410, 500 
 
 cutaneous of neck, 20 
 thigh, 499 
 
 external, 4 
 internal, 499 
 middle, 49 
 dental, anterior, 219 
 posterior, 219 
 descendens noni, 35 
 dorsal branch of ulnar, 326 
 eighth pair, 15 
 
 origin of, 598 
 external cutaneous of leg, 532 
 
 of musculo-spiral, 
 
 272 
 
 of peroneal, 526 
 of thigh, 410 
 laryngeal, 200 
 respiratory, 72 
 
 of Bell, 271 
 facial, 15, 90 
 
 cervical branch of, 21 
 in temporal bone, 226 
 fifth pair, 13 
 
 origin of, 579 
 first pair, 13 
 
 lumbar, 408 
 fourth cranial, 209 
 
 pair, origin of, 597 
 (patheticus), 13 
 frontal, 208 
 
 genital branch of genito-crural, 410 
 genito-crural, 356, 409, 500 
 
 KEE 
 
 NEBYES (continued') 
 
 gluteal, external, 540 
 inferior, 540 
 superior, 445, 536 
 glosso-pharyngeal, 15, 108, 206 
 great ischiatic, 538 
 
 occipital, 5, 310 
 gustatory. 50, 106 
 hypoglossal, 15, 49, 114 
 ilio-hypogastric, 356, 409 
 
 inguinal, 356, 409, 500 
 incisor, 106 
 inferior dental, 106 
 
 laryngeal or recurrent, 145 
 maxillary, 103 
 infra-maxillary of facial, 92 
 orbital of facial, 92 
 
 of superior maxillary, 93 
 trochlear, 93, 214 
 intercostal, 150 
 
 cutaneous branches, 150, 
 
 256 
 
 humeral, 262 
 lateral cutaneous of, 262 
 internal cutaneous of arm, 271 
 interosseous anterior, 295, 296 
 
 posterior, 285, 325, 333 
 ischiatic, 548 
 
 great, 538, 542 
 lesser, 445, 544 
 
 Jacobson's or tympanic, 224, 225 
 lachrymal 209 
 laryngeal, external, 55, 112 
 inferior, 113 
 
 inferior or recurrent, 200 
 internal, 112 
 recurrent, 113 
 superior, 54, 112, 200 
 lateral cutaneous of abdomen, 356 
 lesser cutaneous of arm. 272 
 ischiatic, 445, 539 
 musculo-spiral, 272 
 lingual, 50 
 
 of glosso-pharyngeal, 109 
 long or inferior pudendal, 540 
 long saphenous, 523 
 lumbar, plexus of, 408 
 
 sympathetic, 407 
 lumbo-sacral, 444 
 
 tympanic, 224, 225 
 malar branch of superior maxillary, 
 
 217 
 
 malar of facial, 92 
 median, 282, 294 
 
INDEX. 
 
 687 
 
 NEE 
 
 NER 
 
 NKEVES (continued) 
 
 median in the palm, 302 
 mental, 94, 106 
 masseteric, 104 
 motor oculi, 597 
 motores oculi, 13 
 musculo-cutaneous, 283 
 
 spiral, 284 
 mylo-hyoid, 106 
 
 hyoidean, 45 
 obturator, 410, 524 
 ccsipital, small, 21 
 olfactory, 13, 233, 596 
 optic, 13, 214 
 
 origin of, 596 
 orbital branch of superior maxillary, 
 
 217 
 
 nasal, 213 
 naso-lobular, 82, 93 
 nervi molles, 87 
 nervus accessorius, 26 
 ninth pair, 15 
 
 origin of, 599 
 palatine anterior, 221 
 external, 221 
 nasal branches of, 221 
 smaller, 221 
 naso, 221 
 palmar branch of median, 297 
 
 of ulna, 297 
 
 cutaneous of median, 295 
 peroneal, 539, 542, 
 
 superficial, 419 
 pes anserinus, 91 
 petrosal, external, 227 
 great, 221, 226 
 lesser, 222 
 pharyngeal, 221 
 
 of pneumo-gastric, 112 
 phrenic, 57, 59 
 
 in chest, 132 
 plantar, external, 562 
 internal, 562 
 pneumo-gastric, 15, 225 
 
 in the chest, 145 
 course of, 110 
 popliteal, internal, 543 
 portio dura, 90 
 posterior auricular, 5, 91 
 
 branches of spinal, 242 
 tibial, 556 
 thoracic, 72, 271 
 
 pudendal, inferior or long, 417, 
 419 
 
 NEBVES (continued) 
 pndic, 427, 445 
 pulmonary branches of pneumo-gaa- 
 
 tric, 146 
 
 radial, 285, 292, 325 
 recurrent or inferior laryngeal, 145 
 rhomboid, 315 
 sacral, 443 
 
 fourth, 417 
 saphenous, long, 523, 525 
 
 short, 549 
 second pair, 13 
 
 origin of, 596 
 seventh pair, 15 
 
 origin of, 598 
 short saphenous, 543, 549 
 shoulder, cutaneous of, 317 
 sixth cranial, 216 
 pair, 15 
 origin of, 598 
 small occipital, 5 
 in sphenoidal fissure, 16 
 spinal, 623 
 
 accessory, 15, 113, 314 
 origin of, 623 
 posterior branches of, 242 
 splanchnic, great, 147 
 lesser, 147 
 smallest, 147 
 suboccipital, 228 
 subscapular, 269 
 superior gluteal, 445 
 
 maxillary, 218 
 supra-clavicular, 255 
 
 maxillary branch of facial, 92 
 orbital, 4, 93, 209 
 scapular, 72, 316, 323 
 trochlear, 4, 93, 208 
 sympathetic, cervical, 114 
 
 in the chest, 147 
 in the pelvis, 445 
 
 temporal branch of superior max- 
 illary, 5, 217 
 deep, 104 
 
 anterior, 104 
 posterior, 104 
 temporo-facial, 5, 91 
 
 malar, 94 
 third cranial, 216 
 nerve, 13 
 
 pair, origin of, 597 
 thoracic anterior, 260 
 tonsillar of glosso-pharyngeal, 1 09 
 trifacial, 13 
 
688 
 
 INDEX. 
 
 NEB 
 
 NEBVES (continued) 
 
 trigeminal, origin of, 597 
 
 trochlear, 597 
 
 ulnar, 283, 294 
 
 deep palmar branch of, 309 
 dorsal, cutaneous of, 294 
 in the palm, 301 
 
 vestibular, 659 
 
 vidian, 221, 222 
 
 Nervi molles, 87, 116 
 
 Nervus accessorius, 599 
 NOSE 
 
 arteries of, 232 
 
 cartilages of, 228 
 
 dissection of, 228 
 
 infundibulum of, 230 
 
 interior of, 229 
 
 meatus of, 230 
 
 mucous membrane of, 231 
 
 nerves of, 233 
 
 septum of, 229 
 
 reins of, 233 
 
 (Esophagus, 143 
 
 Olfactory nerve, origin of, 596 
 
 sulcus, 595 
 Olivary bodies, 585 
 
 nucleus, 586 
 Omentum 
 
 gastro-hepatic, 380, 383 
 splenic, 378, 384 
 
 great, 380 
 
 lesser, 383 
 Optic nerve, 596 
 OBBIT 
 
 contents of, 208 
 
 dissection of, 206 
 
 fascia of, 207 
 
 periosteum of, 207 
 Organ of Corti, 661 
 
 of Giraldes, 671 
 
 of hearing, dissection of, 648 
 Os cordis, 165 
 hyoides, 189 
 orbiculare, 653 
 uteri, 468 
 
 Ossicula auditus, 652 
 Otoconia or otoliths, 658 
 Ovaries, situation of, 474 
 Oviducts, 473 
 
 Pacini, corpuscles of, 303, 459 
 
 PIN 
 PAZ.ATB 
 
 arches of, 184 
 hard, 187 
 soft, 183 
 muscles of, 184 
 
 Palm of the hand, dissection of, 297 
 Pancreas, relations of, 393 
 
 situation of, 878 
 Pauniculus carnosus, 18 
 Papilla lachrymalis, 78 
 Parotid gland, 88 
 
 structures within, 89 
 Patella, ligament of, 516 
 Pelvic fascia in female, 465 
 
 viscera, general position of in male. 
 431 
 
 side view of, 429 
 PELVIS 
 
 contents of male, 412 
 dissection of, 411 
 functions of, 411 
 male and female, 411 
 side view of female, 465 
 PENIS 
 
 glans, 455 
 lymphatics of, 459 
 structure of, 455 
 Peptic cells, 490 
 glands, 490 
 Pericardium, 134 
 
 vestigial fold of, 137 
 Peri-lymph, or liquor Cotunnii, 658 
 PERINEUM 
 
 anal division, 414 
 central tendon of, 418 
 in the female, 459 
 male, 414 
 
 urethral division, 414 
 Peritoneum, course of, 379 
 greater cavity of, 381 
 lesser cavity of, 381 
 Pes accessorius, 603 
 anserinus, 74 
 hippocampi, 604 
 Petit, canal of, 646 
 PHARYNX, 
 
 aponeurosis of, 178, 180 
 dissection of, 177 
 fascia of, 178 
 muscles of, 178 
 openings into, 182 
 Pia mater of brain, 579 
 Pineal body, 610 
 Pinna of the ear, 648 
 
INDEX. 
 
 689 
 
 PIN 
 
 Pinna of the ear, arteries of, 649 
 
 cartilage of, 648 
 
 ligaments of, 648 
 
 muscles of, 648 
 
 nerves of, 649 
 
 Pituitary body or gland, 594 
 Platysma, 17 
 Pleura, 139 
 PLEXUS OF NERVES 
 
 Auerbach's, 493 
 
 cervical, 57 
 
 inferior haemorrhoidal, 445 
 
 Meissner's, 493 
 
 mesenteric, or Auerbaeh's, 493 
 
 cesophageal, 146 
 
 patellar, 525 
 
 prostatic, 445 
 
 renal, 487 
 
 sacral, 444 
 
 superior mesenteric, 493 
 uterine, 445, 468 
 vaginal, 445, 466, 468 
 PLEXUSES 
 
 axillary, 267 
 
 brachial, 70, 267 
 
 'anterior, 111 
 
 cardiac, 153 
 
 carotid, 115 
 
 cavernous, 116 
 
 coronary, 153 
 
 hypogastric, 408 
 
 infraorbital, 92 
 
 lumbar, 408 
 
 posterior, 111 
 
 pharyngeal, 109 
 
 pterygoid of veins, 87 
 
 pulmonary anterior, 146 
 posterior, 146 
 
 solar, 385, 407 
 
 of veins, pterygoid, 103 
 Plica semilunaris, 78 
 Pomuni Adami, 190 
 Pons hepatis, 477 
 
 varolii, 587 
 
 minute structure of, 62 13 
 Popliteal space, boundaries of, 541 
 Portio dura, 598 
 
 mollis, 598 
 Porus opticus, 640 
 Poupart's ligament, 504 
 Preputium clitoridis, 460 
 Process, vermiform inferior, 613 
 
 superior, 613 
 Processes, ciliary, 636 
 
 SAC 
 
 Processus a cerebello ad cerebrum, 611 
 
 clavatus, 586 
 Prsecuneus, 593 
 Prostate, 450 
 
 calculi of, 451 
 ducts of, 451 
 gland, position of, 438 
 relations of, 438 
 Promontory of tympanum, 651 
 Pubic symphysis, 565 
 Puncta lachrymalia, 80 
 j Punctum lachrymale, 78 
 Pylorus, glands of, 490 
 
 sphincter of, 489 
 
 Pyramids, anterior of medulla, 58t 
 posterior, 628 
 
 of medulla, 586 
 of tympanum, 651 
 
 Ranula, 44 
 
 Keceptaculum chyli, 142, 39 J 
 
 Rectum, 376 
 
 Rectum, arteries of, 434 
 
 course of, 412 
 
 digital, examination of, 434 
 
 folds of mucous membrane in, 49.) 
 
 relations of, 432 
 
 structure of, 494 
 Reil, fillet of, 627 
 
 island of, 591 
 Recto-vaginal pouch, 465 
 
 vesical pouch, 412 
 Region, infra-clavicular, 258 
 
 prsecordial, 125, 137 
 
 pterygo-raaxillary, 94 
 
 submaxillary, 41 
 
 temporal, 94 
 
 Renal capsules, situation of, 379 
 Respiration, 397 
 Rete mirabile of Galen, 582 
 
 testis, 668 
 Retina, 640 
 
 arteries of, 644 
 
 minute structure of, 642 
 Rima glottidis, 194 
 Ring, crural or femoral, 505, 507 
 
 external abdominal, 358 
 
 internal abdominal, 365 
 Rolando, arciform fibres of, 586 
 Ruysch, tunic of, 637 
 
 Saccule of labyrinth, 658 
 
 Y Y 
 
(590 
 
 INDEX. 
 
 SAC 
 
 TON 
 
 Sacro-iliac symphysis, 565 
 
 baphenous, opening of fascia lata, 499, 501 
 
 Scala tympani, 657 
 
 vestibuli, 657 
 Scalp, arteries of, 3 
 
 dissection of, 1 
 
 lymphatics of, 6 
 
 nerves of, 4 
 strata composing, 1 
 
 surgical interest of, 5 
 
 veins of, 3 
 
 Scarpa's triangle, 510 
 Sclerotic coat of eye, 632 
 Scrotum, dissection of, 665 
 Semi-lunar cartilages of knee, 570 
 Septa, external intermuscular of arm, 275 
 
 internal intermuscular of arm, 275 
 Septum, intermuscular of thigh, 501 
 
 lucidum, 604 
 
 scroti, 665 
 
 pectintforme, 456 
 
 Sheath, for extensor tendons of wrist, 
 327 
 
 of femoral vessels, 506 
 Sheaths, of the rectus abdominis, 362 
 Sigmoid flexure of colon, 376 
 SINUSES 
 
 cavernous, 10, 15 
 
 circular, 10 
 
 coronary, 163 
 
 inferior longitudinal, 10 
 petrosal, 10 
 
 lateral, 9 
 
 of Morgagni, 180 
 
 occipital, 11 
 
 of prostate, 450 
 
 straight, 10 
 
 superior longitudinal, 8 
 petrosal, 10 
 
 transverse, 11 
 
 of Valsalva, 129, 161, 162 
 Solar plexus, 407 
 Sole of the foot, 557 
 Spaces, interpleural, 122 
 Spermatic cord, 670 
 Spigelii lobulus, 476 
 SPINAX CORD 
 
 arachnoid of, 619 
 
 arteries of, 625 
 
 central canal of, 623 
 
 cerebro-spinal fluid of, 618 
 
 commissures of, 622 
 
 columns of, 622 
 
 dissection of, 617 
 
 SPINAL CORD (continued') 
 
 dura mater of, 618 
 
 filum terminate of, 620 
 
 fissures of, 621 
 
 functions of, 62G 
 
 ligamentum denticulatum of. 620 
 
 membranes of, 618 
 
 pia mater of, 6'-'0 
 
 veins of, 618 
 
 Spine, movements of the, 248 
 Spleen, situation of, 378 
 
 suspensory ligament of, 378 
 
 structure of, 48 1 
 Stapes, 653 
 Steno's duct, 89 
 Stomach, position of, 373 
 
 structure of. 488 
 Sub -arachnoid fluid, 579 
 Subdural space, 6 
 
 Supra-renal capsules, structure of. 487 
 Sylvius, fissure of, 588 
 Sympathetic, in the penis, 446 
 Symphysis, pubic, 565 
 
 sacro-iliac, 565 
 
 T<enia Hippocampi, 606 
 
 semi-circularis, 607 
 Tarsal cartilages, 80 
 Tegmentum, 629 
 Tendo Achillis, 550 
 
 oculi, 76 
 
 palpebrarum, 76 
 
 Tendon, central of diaphragm. 396 
 Testis, dissection of, 667 
 
 descent of, 672 
 
 gubernaculum of, 672 
 Tentorium cerebelli, 7 
 Thalamus opticus, 608 
 Thebesii valvula, 158, 164 
 
 foramina, 158 
 
 Theca of flexor tendons in palm, 303 
 Thoracic duct, 1 42 
 Thorax, boundaries of. 118 
 
 dissection of, 118 
 Thyroid body, 36 
 
 structure of, 37 
 
 cartilage, 190 
 TONGUE, arteries of, 206 
 
 dissection of, 201 
 
 fibrous septum of, 206 
 
 frsenum of, 20'2 
 
 glands of, 204 
 
 mucous membrane of, 202 
 
INDEX. 
 
 691 
 
 TON 
 
 VEi 
 
 TONGUE (continued) 
 
 muscular fibres of, 205 
 
 nerves of, 206 
 
 papillae of, 202 
 
 taste buds of, 202 
 Tonsils, 186 
 Torcular Herophili, 11 
 Trabeculae testis, 668 
 Trachea, 169 
 Tracheotomy, 40 
 Transverse meso-colon, 383 
 TRIANGLES, anterior of neck, 28 
 
 digastric, 41 
 
 of Hesselbach, 369 
 
 posterior of neck, 25 
 
 of Scarpa, 510 
 
 sub-occipital, 242 
 
 supra-clavicular, 27 
 Trigone of bladder, 449 
 Triticea cartilage, 190 
 Trochlea of superior oblique muscle, 211 
 Tube, Eustachian, 178, 181 
 
 Fallopian, 464, 473 
 Tuber cinereum, 594 
 Tubuli seminiferi, 670 
 Tunica albuginea of the ovary, 474 
 testis, 667 
 
 vaginalis, 667 
 
 vasculosa, 667, 668 
 Tympanum, 650 
 
 boundaries of, 650 
 
 bones of the, 652 
 
 blood-vessels of, 654 
 
 Uraehus, 372 
 
 Ureter, 436 
 
 Ureters, relations of, 394 
 
 URETHRA, bulb of, 458 
 
 female, 460 
 
 side view of, 466 
 
 lacuna of, 454 
 
 lymphatics of, 465 . 
 
 in the male, 438 
 
 anatomy of, 453 
 UTKKVS, 467 
 
 arteries of, 466 
 
 cervix of, 467 
 
 general position of, 463 
 
 interior of, 470 
 
 ligaments of, 465 
 
 lymphatics of, 469 
 
 mouth of, 468 
 
 mucous membrane of, 472 
 
 UTERUS (continued) 
 
 muscular fibres of, 472 
 
 nerves of, 468 
 Utricle of labyrinth, 658 
 Utriculus of prostate, 450 
 Uvea, 638 
 Uvula, 184 
 
 of bladder, 418 
 
 Vagina. 462 
 
 bulb of, 462 
 
 side view of, 466 
 
 structure of, 469 
 
 sphincter of, $70 
 Vullecula of cerebellum, 614 
 Vilsalva, sinuses of, 129, 161, 162 
 VALVES 
 
 auriculo-ventricular, left, 162 
 right, 159 
 
 Eustachian, 157 
 
 of Houston, 495 
 
 ileo-csecal, 375, 495 
 
 mitral or bicuspid, 162 
 
 pulmonary or semilunar, 160 
 
 tricuspid, 159 
 
 of Vieussens, 612 
 
 of Thebesius, 158, 164 
 Valvulse conniventes, 491 
 Vas aberrans, 671 
 
 deferens, 437, 671 
 
 spirale, 663 
 Vasa efferentia testis, 670 
 
 rscta, 670 
 VEINS 
 
 angular, 87 
 
 anterior jugular, 19 
 
 axillary, 267 
 
 basilic, 274, 286 
 
 brachial, 279 
 
 brachio-cephalic, 126 
 left, 126 
 right, 126 
 
 cardiac anterior, 163 
 great, 163 
 posterior, 163 
 
 cephalic, 259, 274, 286 
 
 circumflexa ilii, deep, 367 
 
 superficial, 356 
 
 comites of brachial artery, 281 
 
 common iliac, relations of, 404 
 
 coronary, 158, 163 
 
 epigastric, 356 
 
 external jugular, 18 
 
092 
 
 INDEX. 
 
 VE1 
 
 VEINS (continued) 
 
 external, pudic, 356 
 
 or short saphena, 525 
 facial, 44, 87 
 frontal, 87 
 of Galen, 10, 608 
 hcemorrhoidal, inferior, 434 
 middle, 434 
 superior, 434 
 plexus, 435 
 intercostal, 149 
 
 superior, 69 
 internal jugular, 34 
 
 mammary, 68, 121 
 
 maxillary, 102 
 
 or long saphena, 525 
 lingual, 52 
 lumbar, 404 
 median, 274, 286 
 
 basilic, 274 
 
 cephalic, 274 
 
 mediana profunda, 274, 286 
 mesenteric inferior, 392 
 superior, 391 
 occipital, 56 
 ophthalmic, 215 
 ovarian, 475 
 pampiniform, 671 
 pharyngeal plexus of, 178 
 popliteal, 544, 553 
 prostatic plexus of, 432 
 pterygoid plexus of, 87, 103 
 pudic, 427 
 radial, 285 
 ranine, 52 
 renal, 402 
 salvatella, 285 
 saphena, internal, 499 
 
 long or internal, 525 
 short or external, 525 
 short or posterior, 545, 548 
 scapular posterior, 68 
 spermatic, 403 
 spinal system of, 617 
 subclavian, 70 
 supra-scapular, 68 
 
 ZIN 
 
 YKINS (continued) 
 
 thyroid inferior, 68 
 superior, 54 
 
 ulnar anterior, 285 
 posterior, 285 
 
 uterine, 468 
 
 vaginal plexus of, 466 
 
 vena portse, 388 
 
 vertebral, 67 
 
 vorticosse, 637 
 VELUM 
 
 interpositum, 579, 607 
 
 posterior medullary, 615 
 Veneris mons, 459 
 Vena cava, inferior, 404 
 
 relations of, 404 
 
 superior, 127 
 Vena azygos major, 141, 170 
 
 minor, 141 
 Venesection, veins and nerves, concerned. 
 
 in, 274 
 Ventricles, fifth, 604 
 
 fourth, 612 
 
 lateral, 602 
 
 left, 162 
 
 right, 158 
 
 septum of, 604 
 
 third, 609 
 
 Veru montanum, 450 
 Vesicles, graafian, 474 
 Vesiculse seminales, 437, 452 
 Vestibule in female pudenda, 460 
 
 of internal ear, 655 
 Villi, structure of, 491 
 Vocal cords, false or superior, 195 
 
 true or inferior, 195 
 
 Willis, circle of, 582 
 Winslow, foramen of, 381 
 
 posterior ligament of, 546 
 Wrisberg, nerve of, 262 
 
 Zinn, zone of, 645 
 
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 BY SAME AUTHOR. 
 
 THE TREATMENT OF PULMONARY CONSUMPTION BY 
 HYGIENE, CLIMATE, AND MEDICINE. With an Appendix on 
 the Sanitaria of the United States, Switzerland, and the Balearic Isl- 
 ands. The Third Edition, much Enlarged. Octavo. Price . $2.50 
 
 
 
 BUCKNILL(joHN CHARLES), M.D., & TUKE (DANIEL H.),M.D. 
 
 A MANUAL OF PSYCHOLOGICAL MEDICINE: containing the 
 Lunacy Laws, the Nosology, CEtiology, Statistics, Description, Diagno- 
 sis, Pathology (including Morbid Histology), and Treatment of Insanity. 
 Fourth Edition, much enlarged, with Twelve Lithographic Plates, and 
 numerous Illustrations. Octavo. Price . . . . $8.00 
 
 This edition will contain a number of pages of additional matter, and, in consequence of 
 recent advances in Psychological Medicine, several chapters will be rewritten, bringing the 
 Classification, Pathology, and Treatment of Insanity up to the present time. 
 
 BURNETT (CHARLES H.), M. D., 
 
 Aurist to {he Presbyterian Hospital, &c. 
 
 HEARING, AND HOW TO KEEP IT. (Vol. I., American Health 
 Primers.) With Illustrations. Cloth. Price . . . $0.50 
 
 BIDDLE OOHN~B.), M. D., 
 
 Professor of Materia Medicaand Therapeutics in the Jefferson Medical College, Philadelphia, &o. 
 
 MATERIA MEDICA, FOR THE USE OF STUDENTS. With 
 Illustrations. Eighth Edition, Revised and Enlarged. Price $4.00 
 
 This new and thoroughly revised edition of Professor Biddle's work has incorporated in 
 it all the improvements as adopted by the New United States Phamiacopoeia just issued. It 
 is designed to present the leading facts and principles usually comprised under this head as 
 set forth by the standard authorities, and to fill a vacuum which seems to exist in the want 
 of an elementary work on the subject. The larger works usually recommended as text-books 
 in our Medical schools are too voluminous for convenient use. This will be found to contain, 
 in a condensed form, all that is most valuable, and will supply students with a reliable guide 
 to the course of lectures on Materia Medica as delivered at the various Medical schools in 
 the United States. 
 
 BALFOUR^cTw.), M. D., 
 
 Physician to the Royal Infirmary, Edinburgh) Lecturer on Clinical Medicine, &c. 
 
 CLINICAL LECTURES ON DISEASES OF THE HEART AND 
 AORTA. With Illustrations. Octavo. Price . . . $4.00 
 
 BYFORD (\v~~rT), A.M., M.D., 
 
 Professor of Obstetrics and Diseases of Women and Children in the Chicago Medical College, &c. 
 
 PRACTICE OF MEDICINE AND SURGERY. Applied to the 
 Diseases and Accidents incident to Women. Second Edition, Revised 
 and Enlarged. Octavo. Price 
 
 SAME AUTHOR. 
 
 ON THE CHRONIC INFLAMMATION AND DISPLACEMENT 
 
 OF THE UNIMPREGNATED UTERUS. A New, Enlarged, and 
 
 Thoroughly Revised Edition, with Numerous Illustrations. 8vo. $2.50 
 
 Dr. Byford writes the exact present state of medical knowledge on the subjects presented; 
 
 and does this so clearly, so concisely, so truthfully, and so completely, that his book on the 
 
 uterus will always meet the approval of the profession, and be everywhere regarded as a 
 
 popular standard work. Buffalo Medical and Surgical Journal. 
 
10 
 BLACK (D. CAMPBELL), M. D., 
 
 L. R. C. S. Edinburgh, Member of the General Council of the University of Glasgow, &c., &c. 
 
 THE FUNCTIONAL DISEASES OF THE RENAL, URINARY, 
 
 and Reproductive Organs, with a General View of Urinary Pathology. 
 
 Price $2.00 
 
 The style of the author is clear, easy, and agreeable, . . . his work is a valuable contri- 
 bution to medical science, and being penned in that disposition of unprejudiced philosophical 
 inquiry which should always guide a true physician, admirably embodies the spirit of its 
 opening quotation from Professor Huxley. Philada. Med. Times. 
 
 BY SAME AUTHOR. 
 LECTURES ON BRIGHT'S DISEASE OF THE KIDNEYS. 
 
 Delivered at the Royal Infirmary of Glasgow. With 20 Illustrations, 
 engraved on Wood. One volume, octavo, in Cloth. Price . $1.50 
 
 BENTLEY AND TRIMEN'S 
 
 MEDICINAL PLANTS. A New Illustrated Work, now Publish- 
 ing in Monthly Parts. Thirty-seven Parts now ready. Eight Colored 
 Plates in each Part. Price, each, ...... $2.00 
 
 This work includes full botanical descriptions, and an account of the properties and uses 
 of the principal plants employed in medicine, especial attention being paid to those which 
 are officinal in the British and United States Pharmacopoaias. The plants which supply 
 food and substances required by the sick and convalescent will be also included. Each spe- 
 cies will be illustrated oy a colored plate drawn from nature. 
 
 BEASLEY (HENRY). 
 
 THE BOOK OF PRESCRIPTIONS. Containing over 3000 
 Prescriptions, collected from the Practice of the most Eminent Physi- 
 cians and Surgeons English, French, and American; comprising also 
 a Compendious History of the Materia Medica, Lists of the Doses of all 
 Officinal and Established Preparations, and an Index of Diseases and 
 their Remedies. Fifth Edition, Revised and Enlarged. Price $2.25 
 
 BY SAME AUTHOR. 
 
 THE POCKET FORMULARY: A Synopsis of the British and 
 Foreign Pharmacopoeias. Tenth Revised Edition. Price . $2.25 
 
 THE DRUGGIST'S GENERAL RECEIPT BOOK AND VETERI- 
 NARY FORMULARY. Eighth Edition. Just Ready. Price, $2.25 
 
 BIRCH (s. B.), M. D., 
 
 Member of the Royal College of Physicians, &c. 
 
 CONSTIPATED BOWELS ; the Various Causes and the Different 
 Means of Cure. Third Edition. Price . . . . $1.00 
 
 BRAUNE BELLAMY. 
 
 AN ATLAS OF TOPOGRAPHICAL ANATOMY. After Plane 
 Sections of Frozen Bodies, containing Thirty-four Full-page Photo- 
 graphic Plates and numerous other Illustrations on Wood. By WILHELM 
 BRAUNE, Professor of Anatomy in the University of Leipzig. Trans- 
 lated and Edited by EDWARD BELLAMY, F. R. C. S., Senior Assistant Sur- 
 geon to, and Lecturer on Anatomy and Teacher of Operative Surgery 
 at, the Charing Cross Hospital, London. A large quarto volume. 
 Price in cloth, $12.00 ; half morocco, ..... $14.00 
 
11 
 
 COHEN (i. SOLIS), M.D. 
 
 Lecturer on Laryngoscopy and Diseases of the Throat and Chest in Jefferson Medical College. 
 
 ON INHALATION. ITS THERAPEUTICS AND PRACTICE 
 
 Including a Description of the Apparatus employed, &c. With Cases 
 and Illustrations. A New Enlarged Edition. Price . . $2.50 
 
 SAME AUTHOR. 
 CROUP. In its Relations to Tracheotomy. Price . . $1.00 
 
 CARSON (JOSEPH), M.D., 
 
 Professor of Materia Medica and Pharmacy in the University. 
 
 A HISTORY OF THE MEDICAL DEPARTMENT OF THE 
 UNIVERSITY OF PENNSYLVANIA, from its Foundation in 1765: 
 with Sketches of Deceased Professors, &c. .... $2.00 
 
 ^ f / 
 
 CHARTERIS (MATHEW), M. D., 
 
 Member of Hospital Staff and Professor in University of Glasgow. 
 
 STUDENTS' HAND-BOOK OF THE PRACTICE OF MEDI- 
 CINE. With Microscopic and other Illustrations. Price . $2.00 
 
 Tli is book forms one volume of the Students' Guide Series, or Text-Books, now in course 
 of publication- 
 
 CARPENTER (w. B.), M.D., F.R.S. 
 
 THE MICROSCOPE AND ITS REVELATIONS. The Fifth 
 
 London Edition, Revised and Enlarged, with more than 500 Illustra- 
 tions. . . . . . . . . . . $5-oo 
 
 CORR (L. H.), M.D. 
 
 OBSTETRIC CATECHISM, or Obstetrics reduced to Questions 
 
 and Answers. With Numerous Illustrations. Price . . 2.00 
 
 CHAVASSE (P. HENRY), F.R.C.S., 
 
 Author of Advice to a Wife, Advice to a Mother, &c. 
 
 APHORISMS ON THE MENTAL CULTURE AND TRAIN- 
 ING OF A CHILD, and on various other subjects relating to Health 
 and Happiness. Addressed to Parents. Price . . . $1.00 
 Dr. Cliayasse's works have been very favorably received and had a large circulation, the 
 value of his advice to WIVES and MOTHERS having thus been very generally recognized. 
 This book is a sequel or companion to them, and it will be found both valuable and important 
 to all who have the care of families, and who want to bring up their children to become useful 
 men and women. It is full of fresh thoughts and graceful illustrations. 
 
 CLARKE (W.FAIKLIE), M.D., 
 
 Assistant Surgeon to Charing Cross Hospital, 
 
 CLARKE'S TREATISE ON DISEASES OF THE TONGUE. 
 
 With Lithographic and Wood-cut Illustrations. Octavo. Price $4.50 
 It contains The Anatomy and Physiology of the Tongue, Importance of its Minute Exam- 
 ination, Its Congenital Defects, Atrophy, Hypertrophy, Parasitic Diseases, Inflammation, 
 Syphilis and its effects, Various Tumors to which it is subject, Accidents, Injuries, &c., &c. 
 
 COOPER (s.). 
 
 A DICTIONARY OF PRACTICAL SURGERY AND ENCY- 
 CLOPEDIA OF SURGICAL SCIENCE. New Edition, brought 
 down to the present time. By SAMUEL A. LANE, F.R.C.S., assisted by 
 other eminent Surgeons. In two vols., of over 1000 pages each. $12.00 
 
12 
 CLAY (CHARLES), M. D. 
 
 Fellow of the London Obstetrical Society, &d 
 
 THE COMPLETE HAND-BOOK OF OBSTETRIC SURGERY, 
 
 or, Short Rules of Practice in Every Emergency, from the Simplest to 
 the most Formidable Operations in the Practice of Surgery. First 
 American from the Third London Edition. With numerous Illustra- 
 tions. In one volume. $2.00 
 
 CHAMBERS (THOMAS K.), M. D., 
 
 LECTUR'ES, CHIEFLY CLINICAL. Illustrative of a^ Restorative 
 
 System of Medicine. 
 
 CORMACK (SIR JOHN ^SE),^ B., F. R. S. E., M. D. 
 
 Edinburgh and Paris, Fellow Royal College of Physicians, Physician to \he Hertford British Hospital, Paris, &c. 
 
 CLINICAL STUDIES, Illustrated by Cases observed in Hospital and 
 Private Practice. With Illustrative Plates. 2 Volumes. Octavo. $5.00 
 
 COBBOLD (T. SPENCER), M. D., F. R. S. 
 
 PARASITES : A Treatise on the Entozoa of Man and Animals ; 
 including some Account of the Ectozoa. With 85 Engravings. Oc- 
 tavo. Price . . . . . . . . . $5.00 
 
 CLEAVELAND (c. H.), M.D., 
 
 Member of the American Medical Association, &c. 
 
 A PRONOUNCING MEDICAL LEXICON. Containing the Cor- 
 rect Pronunciation and Definition of Terms used in Medicine and the 
 Collateral Sciences. Improved Edition, Cloth, $1.00; Tucks, $1.25 
 This work is not only a Lexicon of all the words in common use in Medicine, but it is 
 also a Pronouncing Dictionary, a feature of great value to Medical Students. To the Dis- 
 penser it will prove an excellent aid, and also to the Pharmaceutical Student. It has received 
 strong commendation both from the Medical Press and from the profession. 
 
 COLES (OAKLEY), D.D.S. 
 
 Dental Surgeon to the Hospital for Diseases of the Throat, Sic. 
 
 A MANUAL OF DENTAL MECHANICS. Containing much 
 information of a Practical Nature for Practitioners and Students. 
 
 INCLUDING 
 
 The Preparation of the Mouth for Artificial Teeth, on Taking Impressions, Various 
 Modes of Applying Heat in the Laboratory, Casting in Plaster of Paris and Metal, 
 Precious Metals used in Dentistry, Making Gold Plates, Various Forms of Porcelain 
 used in Mechanical Dentistry, Pivot Teeth, Choosing and Adjusting Mineral Teeth, the 
 Vulcanite Base, the Celluloid Base, Treatment of Deformities of the Mouth, Receipts 
 for Making Gold Plate and Solder, etc., etc. 
 With 140 Illustrations. Price . . $2.00 
 
 SAME AUTHOR. 
 
 ON DEFORMITIES OF THE MOUTH, CONGENITAL AND 
 ACQUIRED, with their Mechanical Treatment. Second Edition, Re- 
 vised and Enlarged. With Illustrations. Price, . 
 
 DOMVILLE (EDWARD j.), M. D. 
 
 A MANUAL FOR HOSPITAL NURSES and Others engaged in 
 Attending the Sick. i2mo. Price . . . . . gi.oo 
 
13 
 CLARK (F. LE GROS), F. R. S., 
 
 Senior Surgeon to St. Thomas's Hospital. 
 
 OUTLINES OF SURGERY AND SURGICAL PATHOLOGY, 
 
 including the Diagnosis and Treatment 'of Obscure and Urgent Cases, 
 and the Surgical Anatomy of some Important Structures and Regions. 
 Assisted by W. W. WAGSTAFFE, F. R. C. S., Resident Assistant-Surgeon 
 of, and Joint Lecturer on Anatomy at, St. Thomas's Hospital. Second 
 Edition, Revised and Enlarged. Price . . . . $2.00 
 
 COTTLE (E. WYNDHAM), M. A... F. R. C. S., &c. 
 
 THE HAIR IN HEALTH AND DISEASE. Partly from Notes 
 by the late GEORGE NAYLER, F. R. C. S., Surgeon to the Hospital for 
 Diseases of the Skin, &c. i8mo. Cloth. Price . . $0.75 
 
 CURLING (T. B.), F. R. S., 
 
 Consulting Surgeon to the London Hospital, &c. 
 
 A PRACTICAL TREATISE ON THE DISEASES OF THE 
 TESTIS AND OF THE SPERMATIC CORD AND SCROTUM. 
 
 Fourth Revised and Enlarged Edition. Octavo. Price. . $5.50 
 
 BY SAME AUTHOR. 
 
 OBSERVATIONS ON DISEASES OF THE RECTUM. With 
 
 Illustrations. Fourth Edition, Revised and Enlarged. Octavo. Cloth. 
 
 Price ........... $2.75 
 
 CAZEAUX (P.), M. D., 
 
 Adjunct Professor of the Faculty of Medicine, Paris, etc. 
 
 A THEORETICAL AND PRACTICAL TREATISE ON MIDWIFERY, 
 including the Diseases of Pregnancy and Parturition. Translated from 
 the Seventh French Edition, Revised, Greatly Enlarged, and Improved, 
 by S. TARNIER, Clinical Chief of the Lying-in Hospital, Paris, etc., 
 with numerous Lithographic and other Illustrations. Price, in Cloth, 
 $6.00; in Leather ........ $7-oo 
 
 M. Cazeaux's Great Work on Obstetrics has become classical in its character, and almost 
 an Encyclopaedia in its fulness. Written expressly for the use of students of medicine, its 
 teachings are plain and explicit, presenting a condensed summary of the leading principles 
 established by the masters of the obstetric art, and such clear, practical directions for the 
 management of the pregnant, parturient, and puerperal states, as have been sanctioned by 
 the most authoritative practitioners, and confirmed by the author's own experience. 
 
 DOBELL (HORACE), M. D., 
 
 Senior Physician to the Hospital. 
 
 WINTER COUGH (CATARRH, BRONCHITIS, EMPHYSEMA, 
 
 ASTHMA). Lectures Delivered at the Royal Hospital for Diseases of 
 the Chest. The Third Enlarged Edition, with Colored Plates. Octavo. 
 Price . $3.50 
 
 BY SAME AUTHOR. 
 
 ON LOSS OF WEIGHT, BLOOD-SPITTING, AND LUNG 
 DISEASE. With a Colored Frontispiece of the Lung, a Tabular Map, 
 &c., &c. Octavo. Cloth. Price $3-25 
 
14 
 DIXON (JAMES), F. R. C. S. 
 
 Surgeon to the Royal London Ophthalmic Hospital, &c. 
 
 A GUIDE TO THE PRACTICAL STUDY OF DISEASES OF 
 THE EYE, with an Outline of their Medical and Operative Treatment, 
 with Test Types and Illustrations. Third Edition, thoroughly Revised, 
 and a great portion Rewritten. Price . . . . . $2.00 
 
 Mr. Dixon's book is essentially a practical one, written by an observant author, who brings 
 to his special subject a sound knowledge of general Medicine and Surgery. Dublin Quarte fly 
 
 DILLNBERGER (DR. EMIL). 
 
 A HANDY-BOOK OF THE TREATMENT OF WOMEN AND 
 CHILDREN'S DISEASES, according to the Vienna Medical School 
 Part I. The Diseases of Women. Part II. The Diseases of Children. 
 Translated from the Second German Edition, by P. NICOL, M. D. 
 Price $i-5 
 
 Many practitioners will be glad to possess this little manual, which gives a large mas* 
 of practical hints on the treatment of diseases which probably make up the larger half oi 
 everv-day practice. The translation is well made, and explanations of reference to German 
 medicinal preparations are given with proper fulness. The Practitioner. 
 
 DUNGLISON (RICHARD j.), M. D. 
 
 THE PRACTITIONER'S REFERENCE BOOK. Containing 
 Therapeutic and Practical Hints, Dietetic Rules and Precepts, and 
 other General Information Useful to the Physician, Pharmacist, and 
 Student. Octavo. Cloth. Price . . . . $3-5 
 
 DUCHENNE (DR. G. B.). 
 
 LOCALIZED ELECTRIZATION AND ITS APPLICATION 
 TO PATHOLOGY AND THERAPEUTICS. Translated by HER- 
 BERT TIBBITS, M.D. With Ninety-two Illustrations. Price . $3.00 
 Duchenne's great work is not only a well-nigh exhaustive treatise on the medical uses of 
 Electricity, but it is also an elaborate exposition of the different diseases in which Electric- 
 ity has proved to be of value as a therapeutic and diagnostic agent. 
 
 PART II., illustrated by chromo-l'thographs and numerous wood-cuts, is preparing. 
 
 DURKEE (SILAS), M.D., 
 
 Fellow of the Massachusetts Medical Society, &.c, 
 
 GONORRHCEA AND SYPHILIS. The Sixth Edition, Revised 
 and Enlarged, with Portraits and Eight Colored Illustrations. Octavo. 
 
 Price . $3.50 
 
 Dr. Durkee's work impresses the reader in favor of the author by its general tone, the 
 thorough honesty everywhere evinced, the skill with which the book is arranged, the man- 
 ner in which the facts are cited, the clever way in which the author's experience is brought 
 in, the lucidity of the reasoning, and the care with which the therapeutics of venereal coin 
 plaints are treated. Lancet. 
 
 DRUITT (ROBERT), F.R.C.S. 
 
 THE SURGEON'S VADE-MECUM. A Manual of Modern Sur- 
 gery. The Eleventh Revised and Enlarged Edition, with 369 Illus- 
 trations. Price . SS-oo 
 
15 
 DALBY (w. B.), F.R. C.S., 
 
 Aural Surgeon to St. George's Hospital. 
 
 LECTURES ON THE DISEASES AND INJURIES OF THE 
 EAR. Delivered at St. George's Hospital. With Illustrations. 
 Price $1.50 
 
 We cordially recommend this admirable volume by Mr. Dalby as a trustworthy guide in 
 the treatment of the affections of the ear. The book is moderate in price, beautifully illus- 
 trated by wood-cuts, and got up in the best style. Glasgow Medical Journal. 
 
 DAY (WILLIAM HENRY), M. D., 
 
 Physician to the Samaritan Hospital for Women and Children, &c. 
 
 HEADACHES, THEIR NATURE, CAUSES, AND TREAT- 
 MENT. Second Edition. 121110. Cloth. Price . . $2.00 
 
 DUNGLISON (ROBLEY), M. D., 
 
 Late Professor of Institutes of Medicine, &c., in the Jefferson Medical College. 
 
 A HISTORY OF MEDICINE, from the Earliest Ages to the Com- 
 mencement of the Nineteenth Century. Edited by his son, RICHARD 
 J. DUNGLISON, M. D. . . . . . . . $2.50 
 
 ELLIS (EDWARD), M. D., 
 
 Physician to the Victoria Hospital for Sick Children, &c. 
 
 A PRACTICAL MANUAL OF THE DISEASES OF CHIL- 
 DREN, with a Formulary. Third Enlarged Edition, Revised and 
 Improved. One volume. . . . . . . . 2.00 
 
 The AUTHOR, in issuing this new edition of his book, says : "I have very carefully revised 
 each chapter, adding several new sections, and making considerable additions where tht 
 subjects seemed to require fuller treatment, without, however, sacrificing conciseness ot 
 inutiily increasing the bulk of the volume." 
 
 FOTHERGILL (j. MILNER), M. D., 
 
 Assistant Physician to City of London Hospital for Diseases of the Chest, &c. 
 
 THE HEART, ITS DISEASES AND THEIR TREATMENT, 
 
 including the Gouty Heart. Second Edition, Entirely Rewritten and 
 Enlarged, with Two Full-Page Lithographic Plates and Forty other 
 Illustrations. Octavo. Price ...... $3.50 
 
 " Dr. Fothergill's remarks on rest, on proper blood nutrition in Heart Disease, in the 
 treatment of Sequelae of it, and on the action of special medicines, all indicate that in study- 
 ing the pathology of Heart Disease, he has earnestly kept in view the best means of mitigat- 
 ing suffering and of prolonging life." Lancet. 
 
 FOX (CORNELIUS B.), M. D. 
 
 SANITARY EXAMINATIONS of Water, Air, and Food. 94 En- 
 gravings. 8vo. Price $4.00 
 
 FOX (TILBURY), M. D., F. R. C. P. 
 
 Physician to the Department for Skin Diseases in University College Hospital. 
 
 ATLAS OF SKIN DISEASES. Consisting of a Series of Colored 
 Illustrations, in Monthly Parts, together with Descriptive Text and 
 Notes upon Treatment ; each Part containing Four Plates, reproduced by 
 Chromo-Lithography from the work of Willan & Bateman, or taken from 
 Original Sources. Now Complete in 18 Parts. Price, per Part, $2.00 ; 
 or in one large Folio volume, bound in cloth. Price . . $30.00 
 
16 
 
 FENNER (c. s.), M. D., &c. 
 
 VISION: ITS OPTICAL DEFECTS, and the Adaptation of Spec- 
 tacles ; embracing Physical Optics, Physiological Optics, Errors of Re- 
 fraction and Defects of Accommodation, or Optical Defects of the Eye. 
 With 74 Illustrations. Selections from the Test Types of Jaeger and 
 Snellen, etc. Octavo. Price $3-5 
 
 FOSTER (BALTHAZAR), M.D., 
 
 Professor of Medicine in Queen's College. 
 
 LECTURES AND ESSAYS ON CLINICAL MEDICINE. Re- 
 vised and Enlarged by the Author. With Engravings. Octavo. 
 Price $3- 
 
 FRANKLAND (E.), M. D., F. R. S., &c. 
 
 HOW TO TEACH CHEMISTRY, being the substance of Six 
 Lectures to Science Teachers. Reported, with the Author's sanction, 
 by G. George Chaloner, F. C. S., &c. With Illustrations . $1.25 
 
 FULTON (;.), M. D., 
 
 Professor of Physiology, Trinity Medical College, Toronto, 
 
 A TEXT-BOOK OF PHYSIOLOGY. Second Edition, Revised 
 and Enlarged. With numerous Illustrations. Octavo. Price $4.00 
 
 FLINT (AUSTIN), M.D., 
 
 Professor of the Principles and Practice of Medicine, &.C., Bellevue Hospital College, New York. 
 
 CLINICAL REPORTS ON CONTINUED FEVER. Based on 
 an Analysis of One Hundred and Sixty-four Cases, with Remarks on 
 the Management of Continued Fever; the Identity of Typhus and 
 Typhoid Fever; Diagnosis, &c., &c. Octavo. Price . . $2.00 
 
 GANT (FREDERICK j.), F. R. C. S., 
 
 Assisted by Drs. Morrell Mackenzie, Barnes, Erasmus Wilson, and other Specialists. 
 
 THE SCIENCE AND PRACTICE OF SURGERY. Second 
 Edition. 1700 Pages. 1000 Illustrations. 2 Vols. Price, cloth, $11.00 ; 
 sheep ........... $13.00 
 
 DISEASES OF THE BLADDER, PROSTATE GLAND, AND 
 
 URETHRA, including a Practical View of Urinary Diseases, Deposits, 
 and Calculi. Fourth Edition, Revised and Enlarged. With New Il- 
 lustrations. Now Ready. Price . . . . . $3- 50 
 
 GODLEE (R. j.), M. D., 
 
 Assistant-Surgeon University College Hospital. 
 
 AN ATLAS OF HUMAN ANATOMY. Illustrating the Anatomy 
 of the Human Body, in a Series of Dissections. Accompanied by 
 References and an Explanatory Text. To be completed in Twelve or 
 Thirteen Bi-monthly Parts, Folio Size, each Part containing Four large 
 Colored Plates, or Eight Figures. Seven Parts Now Ready. Price per 
 Part $2.50 
 
/ 
 
 GROSS (SAMUEL D.), M. D., 
 
 Professor of Surgery in the Jefferson Medical College, Philadelphia, etc. 
 
 /AMERICAN MEDICAL BIOGRAPHY OF THE NINETEENTH 
 CENTURY. With a Portrait of BENJAMIN RUSH, M.D. Octavo. $3.50 
 
 GREENHOW (E. HEADLAM). M. D., 
 
 Fellow of the Royal Collegi of Physicians, etc. 
 
 ON CHRONIC BRONCHITIS, Especially as Connected with Gout, 
 Emphysema, and Diseases of the Heart. Price . . . $1.50 
 
 ADDISON'S DISEASE. Illustrated by numerous Cases and 5 
 
 full page Colored Engravings. Price ..... $3.00 
 
 GOWERS (w. R.), M. D., F. R. C. P., 
 
 Assistant Professor of Clinical Medicine in University College, 
 
 A MANUAL AND ATLAS OF MEDICAL OPHTHALMO- 
 SCOPY. With 16 Colored, Autotype, and Lithographic Plates, and 
 26 Woodcuts, comprising 112 original Illustrations of the Changes in 
 the Eye in Diseases of the Brain, Kidneys, etc. Octavo. . . $6.00 
 
 GALLABIN (ALFRED LEWIS), M. D., 
 
 Assistant Obstetric Physician and Joint Lecturer on Midwifery, Guy's Hospital, &c. 
 
 THE STUDENT'S GUIDE TO THE DISEASES OF WOMEN". 
 With Numerous Illustrations. i2mo. Cloth. Price . . $2.00 
 
 HIGGINS (CHAMPS), F. R. C. S., 
 
 Ophthalmic Surgeon, Guy's Hospital, die, 
 
 HINTS ON OPHTHALMIC OUT-PATIENT PRACTICE. Sec- 
 ond Edition. i6mo. Cloth. Price .... 60 cts. 
 
 HUNTER (CHARLES). 
 
 MECHANICAL DENTISTRY. A Practical Treatise on the Con- 
 struction of the Various Kinds of Artificial Dentures, with Formulae, 
 Receipts, &c. 100 Illustrations. Price .... $2.25 
 
 HEATH (CHRISTOPHER), F. R. C. S., 
 
 Surgeon to University Colege Hospital and Holme Professor of Clinical Surgery in Univers *y College. 
 
 OPERATIVE SURGERY. Elegantly Illustrated by 20 Large Col- 
 ored Plates, Imperial Quarto Size, each Plate containing several Fig- 
 ures, drawn from Nature by M. Leveille, of Paris, and Colored by hand 
 under his direction. Complete in Five Quarterly Parts. Price, per Part, 
 $2 50 ; or in one volume, handsomely bound in cloth. Price $14.00 
 
 HEWITT (GRAIIY), M. D., 
 
 Physician to the British Lying-in Hospital, and Lecturer on Diseases of Women and Children, &c. 
 
 THE DIAGNOSIS, PATHOLOGY, AND TREATMENT OF 
 DISEASES OF WOMEN, including the Diagnosis of Pregnancy. 
 Founded on a Course of Lectures delivered at St. Mary's Hospital 
 Medical School. The Third Edition, Revised and Enlarged, with 
 new Illustrations. Octavo. Price in Cloth ... . ^4.00 
 
 " Leather . . . 5.00 
 
 This new edition of Dr. Hewitt's book has been so much modified, that it may be considered 
 substantially a new book ; very much of the matter has been entirely rewritten "and the whole 
 work has been rearranged in such a manner as to present a most decided improvement over 
 previous editions. Dr. Hewitt is the leading clinical teacher on Diseases of "Women in London, 
 and the characteristic attention paid to Diagnosis by him has given h b work great popularity. 
 
18 
 HILLIER (THOMAS), M. D., 
 
 Physician to the Hospital for Sick Children, &c 
 
 A CLINICAL TREATISE ON THE DISEASES OF CHILDREN. 
 Octavo. Price ......... $2.00 
 
 HANDY'S TEXT-BOOK OF ANATOMY and Guide to Dissec- 
 tions for the Use of Students. 312 Illustrations. Octavo . $3.00 
 
 HOLDEN (LUTHER), RR.C.S. 
 HUMAN OSTEOLOGY, comprising a Description of the Bones 
 
 with Delineations of the Attachments of the Muscles, &c. With 
 
 numerous Illustrations. Fifth Edition, carefully Revised. Price, $5.50 
 HOLDEN'S MANUAL OF DISSECTIONS OF THE HUMAN 
 
 BODY. Fourth London Edition. With Illustrations. Price 
 LANDMARKS, MEDICAL AND SURGICAL. Second Edition, 
 
 Revised and Enlarged. Price . . . . . . $1.00 
 
 HARRIS (CHAPIN A.), M. D., D. D. S. 
 
 Late President of and Professor of the Principles and Practice of Dental Surgery in the Baltimore College, &c, 
 
 THE PRINCIPLES AND PRACTICE OF DENTISTRY. Tenth 
 
 Revised Edition. . In great part rewritten, rearranged, and with many 
 new and important Illustrations. Including i. Dental Anatomy and 
 Physiology. 2. Dental Pathology and Therapeutics. 3. Dental Sur- 
 gery. 4. Dental Mechanics. Edited by P. H. AUSTEN, M.D., Pro- 
 fessor of Dental Science and Mechanism in the Baltimore College of 
 Dental Surgery. With nearly 400 Illustrations, including many new 
 ones made especially for this edition. Royal octavo. Price, in cloth, 
 $6.50; in leather ........ $7.50 
 
 This new edition of Dr. Harris's work has been thoroughly revised in all its parts more 
 so than any previous edition. So great have been the advances in many branches of dentistry, 
 that it was found necessary to rewrite the articles or subjects, and this has befcn done in the 
 most efficient manner by Professor Austen, for many years an associate and friend of Dr. 
 Ptarris. assisted by Professor Gorgas and Thomas S. Latimer, M.D. The publishers feel 
 assured that it will nosv be found the most complete text-book for the student and guide lor 
 the practitioner in the English language. 
 
 SAME AUTHOR. 
 
 A DICTIONARY OF MEDICAL TERMINOLOGY, DENTAL 
 SURGERY, AND THE COLLATERAL SCIENCES. Fourth Edition, 
 .Carefully Revised and Enlarged, by FERDINAND J. S. GORGAS, M. D., 
 D.D.S., Professor of Dental Surgery in the Baltimore College, &c., &c. 
 Royal octavo. Price, in cloth, $6.50; in leather . . $7-5 
 The many advances in Dental Science rendered it necessary that this edition should be 
 thoroughly revised, which has been done in the most satisfactory manner by Professor Gorgas, 
 Dr. Harris's successor in the Baltimore Dental College, he having added nearly three thou- 
 sand new words, besides making many additions and corrections. The doses of the more 
 prominent medicinal agents have also been added, and in every way the book lias been greatly 
 improved, and its value enhanced as a work of reference. 
 
 HABERSHON (s. o.), M. D., F. R. C. P., 
 
 Senior Physician, Guy's Hospital. 
 
 ON DISEASES OF THE ABDOMEN, STOMACH, and Other 
 Parts of the Alimentary Canal. Third London Edition. Price, $5.00 
 
 ON DISEASES OF THE STOMACH : The Varieties of Dyspepsia, 
 their Diagnosis and Treatment. Third Edition. Octavo . $1.75 
 
19 
 
 HARDWICH AND DAWSON. 
 
 HARDWICH'S MANUAL OF PHOTOGRAPHIC CHEMISTRY. 
 
 With Engravings. Eighth Edition. Edited and Rearranged by G. 
 DAWSON, Lecturer on Photography, &c., &c. 121110 . . $2.00 
 
 HARLAN (GEORGE c.), M. D., 
 
 Surgeon to Wills' Eye Hospital, &c. 
 
 EYESIGHT, AND HOW TO CARE FOR IT. (Vol. IV., Amer- 
 ican Health Primers.) Cloth. Price . . . . $0.50 
 
 HEADLAND (F. w.), M. D., 
 
 Fellow of the Royal College of Physicians, S.C., &c. 
 
 ON THE ACTION OF MEDICINES IN THE SYSTEM. Sixth 
 American from the Fourth London Edition. Revised and Enlarged. 
 Octavo. Price ......... $3.00 
 
 Dr. Headland's work gives the only scientific and satisfactory view of the action of medi- 
 cine; and this not in the way of idle speculation, but by demonstration and experiments, 
 and inferences almost as indisputable as demonstrations. It is truly a great scientific work 
 in a small compass, and deserves to be the hand-book of every lover of the Profession. It 
 has received the approbation of the Medical Press, both in this country and in Europe, and 
 is pronounced by them to be the most original and practically useful work that has been 
 issued for many yeara. 
 
 HOFF (o.), M. D. 
 
 ON H^EMATURIA as a Symptom of Diseases of the Genito-Uri- 
 
 nary Organs. Illustrated. 121110. Cloth. .... $0.75 
 
 HEATH (CHRISTOPHER), F.R.C.S., 
 
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 INJURIES AND DISEASES OF THE JAWS. The Jacksonian 
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 ond Edition, Revised, with over 150 Illustrations. Octavo. Price, 
 
 $4-25 
 
 SAME AUTHOR. 
 
 A MANUAL OF MINOR SURGERY AND BANDAGING, for 
 the Use of House Surgeons, Dressers, and Junior Practitioners. With 
 a Formulae and Numerous Illustrations. i6mo. Price . $2.00 
 
 A GUIDE TO SURGICAL DIAGNOSIS, for Practitioners and 
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 THE DISEASES OF THE HEART AND AORTA. With 81 
 Illustrations. In two volumes, Octavo, of over 1200 pages. Price, $6.00 
 
 HUFELAND (c. w.), M.D. 
 
 THE ART OF PROLONGING LIFE. Edited by ERASMUS WiL- f 
 SON, M. D., F. R. S., &c. i2mo. Cloth $1.00' 
 
 HAY (THOMAS), M. D., 
 
 HISTORY OF A CASE OF RECURRING SARCOMATOUS 
 TUMOUR OF THE ORBIT IN A CHILD. With Three Full Page 
 Illustrations, representing the Tumour in its Various Stages. Price, $0.50 
 
20 
 HEWSON (ADDINELL,) M. D. 
 
 Attending Surgeon Pennsylvania Hospital, &c. 
 
 EARTH AS A TOPICAL APPLICATION IN SURGERY. 
 Being a full Exposition of its use in all the Cases requiring Topical 
 Applications admitted in the Surgical Wards of the Pennsylvania Hospi- 
 tal during a period of Six Months. With Illustrations. Price $2.50 
 
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 ILLUSTRATIONS OF CLINICAL SURGERY. Consisting of 
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 Diseases, Symptoms and Accidents, also Operations and other Methods 
 of Treatment. With Descriptive Letter-press. 10 Parts Bound, com- 
 plete in itself. Price, $25.00. Parts 1 1 and 1 2 now ready. Price, $2.50 
 ^rospectuses furnished upon application. 
 
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 HODGE ON FCETICIDE, OR CRIMINAL ABORTION. 
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 THE SPHYGMOGRAPH. Its Physiological and Pathological In- 
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 HOOD (PETER), M. D., 
 
 President West Hart's Medic..! Association, &c. 
 
 A TREATISE ON GOUT, RHEUMATISM, AND THE ALLIED 
 
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 Second Edition, Revised and Enlarged. With sorre Considerations 
 on Longevity. Octavo. Price . . . . . $3-5 
 
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 A PRACTICAL TREATISE ON AURAL SURGERY. Illus- 
 trated. i2mo. Price . . . . . . . . $1.50 
 
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 DEFECTS OF SIGHT AND HEARING. Their Nature, Causes, 
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 EDWARD H. SIEVEKING, M.D. , F.R.C.P., Physician to St. Mary's Hos- 
 pital. A New and Enlarged Edition. Edited by J. F. PAYNE, M.B., 
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21 
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 SORE THROAT: Its Nature.Varieties, and Treatment, and its Con- 
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 Price $2.00 
 
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 Being a Series of Colored Plates, containing 62 Figures. With appro- 
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 M.D., Surgeon to the Cork Ophthalmic and Aural Hospital. 4to. 
 Cloth. Price ......... $6.00 
 
 KIDD (jo.sEPH)JVrD., M. R. C. S. 
 
 THE LAWS OF THERAPEUTICS, or The Science and Art of 
 Medicine. i2mo. Cloth. Price . . . . . $1.25 
 
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 use in Medicine and the Collateral Sciences. The Pronunciation being 
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 241110. Cloth. Price, $1.00; in Leather, with Tucks and Pocket, $1.25 
 
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 24mo pages, very carefully prepared by the author, who has had much experience in the 
 preparation of similar works, assisted by the Professors of Chemistry and of Botany in one 
 of our leading Medical Colleges. It contains all medical terms in common use, with their 
 pronunciation and definition, without being encumbered, with obsolete or useless words. 
 It is essentially new in many of its features, and fully brought up to the present state of 
 medical science. 
 
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 Surgeon to the Royal London Ophthalmic Hospital. 
 
 DISEASES AND INJURIES OF THE EYE, THEIR MEDICAL 
 AND SURGICAL TREATMENT. Containing a Formulary, Test 
 Types, and Numerous Illustrations. Price .... $2.00 
 
 LEBER & ROTTENSTEIN (DRS.). 
 
 DENTAL CARIES AND ITS CAUSES. An Investigation into 
 the Influence of Fungi in the destruction of the Teeth, translated by 
 THOMAS H. CHANDLER, D.M.D , Professor of Mechanical Dentistry in 
 the Dental School of Harvard University. With Illustrations. Octavo. 
 Price . ^.25 
 
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 IMPERFECT DIGESTION: ITS CAUSES AND TREATMENT. 
 
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 Professor of Materia Medica and Therapeutics, Montreal College. 
 
 CHEMIA COARTATA ; or, The Key to Modern Chemistry. With 
 Numerous Tables, Tests, &c., &c. Price, .... $2.25 
 
22 
 LEWIN (DR. GEORGE). 
 
 Professor at the Fr.-Wilh. University) and Surgeon-in-Chief of the Syphilitic Wards and Skin Diseases of 
 
 the Charity Hospital, Berlin. 
 
 THE TREATMENT OF SYPHILIS by Subcutaneous Sublimate 
 Injections. With a Lithographic Plate illustrating the Mode and Proper 
 Place of administering the Injections, and of the Syringe used for the 
 purpose. Translated by CARL PRCEGLER, M.D., late Surgeon in the 
 Prussian Service, and E. H. GALE, M.D., late Surgeon in the United 
 States Army. Price . . . . . . . . $1.50' 
 
 MASON (FRANCIS), F. R. C. S., 
 
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 THE SURGERY OF THE FACE. With 100 Illustrations, En- 
 graved on Wood, of Various Operations Performed. Octavo. Cloth. 
 
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 MORRIS "(HENRY), F. R. C. S. 
 
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 Surgeon to the Ophthalmic Hospital, and Professor of Ophthalmic Medicine in the Medical College, Calcutta. 
 
 MANUAL OF THE DISEASES OF THE EYE. The Third 
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 Plates, Diagrams of the Eye, many Illustrations on Wood, Snellen's 
 Test Types, &c., &c. Price . . . . . . $4.00 
 
 MARSH (SYLVESTER). 
 
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 Physician to the Hospital for Diseases of the Throat, &c. 
 
 GROWTHS IN THE LARYNX. Their History, Causes, Symp- 
 toms, &c. With Reports and Analysis of One Hundred Cases. With 
 Colored and other Illustrations. Price ..... $2.00 
 
 OTHER WORKS BY THE SAME AUTHOR. 
 
 THE LARYNGOSCOPE IN THROAT DISEASES. With an 
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 lustrations. Price ........ 
 
 THE DISEASES OF THE THROAT AND NOSE. Including 
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 DIPHTHERIA. Its Nature, Varieties, and Treatment. Price, $o 75 
 
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 THE THROAT. With One Hundred and Fjiiy Formulae for Gar- 
 gles, &c., &c. Fourth Edition. Preparing. 
 
23 
 
 MEIGS AND PEPPER. 
 
 A PRACTICAL TREATISE ON THE DISEASES OF CHIL- 
 DREN. By J. FORSYTH MEIGS, M.D., Fellow of the College of Physi- 
 cians of Philadelphia, &c., &c., and WILLIAM PEPPER, M.D., Physician 
 to the Philadelphia Hospital, &c. Sixth Edition, thoroughly Revised 
 and greatly Enlarged, forming a Royal Octavo Volume of over 1000 
 pages. Price, bound in cloth, $6.00; leather . . . $7.00 
 It is the most complete work on the subject in our language. It contains at once the re- 
 sults of personal, and the experience of others. Its quotations from the most recent author- 
 ities, at home and abroad, are ample, and we think the authors deserve congratulations for 
 having produced a book unequalled for the use of the student and indispensable as a work 
 of reference for the practitioner. American Medical Journal. 
 
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 PRACTICAL SURGERY : Including Surgical Dressings, Bandag- 
 ing, Amputation, &c., &c. 227 Illustrations. For the use of Students. 
 
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 Professor of Obstetrics in the Medical College of Ohio, &.c. 
 
 MEDICAL STUDENT'S VADE MECUM. A Compendium of 
 Anatomy, Physiology, Chemistry, the Practice of Medicine, Surgery, 
 Obstetrics, Diseases of the Skin, Materia Medica, Pharmacy, Poisons, 
 &c., &c. Eleventh Edition, Revised and Enlarged, with 224 Illustra- 
 tions. In cloth ......... $2.00 
 
 MAXSON (EDWIN R.), M.D., 
 
 Formerly Lecturer on the Practice of Medicine in the Geneva Medical College, &c. 
 
 THE PRACTICE OF MEDICINE. ... . $3.00 
 
 MARSHALL (JOHN), F.R.S., 
 
 Professor of Surgery, University College, London. 
 
 PHYSIOLOGICAL DIAGRAMS. Life-size, and Beautifully Col- 
 ored. An Entirely New Edition, Revised and Improved, illustrating 
 the whole Human Body, each Map printed on a single sheet of paper, 
 seven feet long and three feet nine inches broad. 
 
 No. 1. The Skeleton and Ligaments. 
 
 No. 2. The Muscles, Joints, and Animal Me- 
 
 chanics. 
 
 No. 3. The Viscera in Position. The Struc- 
 ture of the Lungs. 
 
 No. 4. The Organs of Circulation. 
 
 No. 5. The Lymphatics or Absorbents. 
 
 No. 6. The Digestive Organs. 
 
 No. 7. The Brain and Nerves. 
 
 No. 8. The Organs of the Senses and Organs 
 
 of the- Voice. Plate 1. 
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 No. 10. The Microscopic Structure of the 
 
 Textures. Plate 1. 
 No. 11. The Microscopic Structure of the 
 
 Textures. Plate 2. 
 
 Price of the Set, Eleven Maps, in Sheets, ..... $50.00 
 " " " " handsomely Mounted on 
 
 Canvas, with Rollers, and varnished, ..... $80.00 
 
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 MADDEN ( T . M.), M. D. 
 
 Author of " Climatology and the Use of Mineral Waters." 
 
 THE HEALTH RESORTS OF EUROPE AND AFRICA for the 
 Treatment of Chronic Diseases. A Hand -Book the result of the 
 Author's own Observations during several years of Health-Travel in 
 many Lands, containing; also, the substance of the Author's former 
 Work on CLIMATOLOGY AND THE USE OF MINERAL WATERS. Octavo. 
 
 Price , . . S?.CQ 
 
24 
 MAUNDER (c. F.), F.R.C.S. 
 
 Surgeon to the London Hospital) formerly Demonstrator of Anatomy at Guy's Hospital. 
 
 OPERATIVE SURGERY. Second Edition, with One Hundred 
 and Sixty-four Engravings on Wood. Price . . . $2.25 
 
 BY SAME AUTHOR. 
 
 SURGERY OF THE ARTERIES, including Aneurisms. Wounds, 
 Haemorrhages, Twenty-seven Cases of Ligatures, Antiseptic, etc. With 
 18 Illustrations. Price ........ $1.50 
 
 MAYNE (R. G.), M. D., AND MAYNE (j.), M. D. 
 
 MEDICAL VOCABULARY: An Explanation of all Names, 
 Synonyms, Terms, and Phrases used in Medicine and the Relative 
 Branches of Medical Science. 4th Edition. 450 pages. Price, $3.00 
 
 MAYS (THOMAS ;.), M. D. 
 
 ON THE THERAPEUTIC FORCES. An Effort to Consider the 
 Action of Medicines in the Light of the Doctrine of Conservation of 
 Force. I2mo. Cloth. Price . . . . . . $1.25 
 
 MARTIN (JOHNH.). 
 
 Author of Microscopic Objects, &c. 
 
 A MANUAL OF MICROSCOPIC MOUNTING. With Notes on 
 the Collection and Examination of Objects, and upwards of One Hun- 
 dred and Fifty Illustrations. Second Edition, Enlarged. Price, $2.75 
 
 MEADOWS (ALFRED), M. D. 
 
 Physician to the Hospital for Women, and to the General Lying-in Hospital, &c. 
 
 MANUAL OF MIDWIFERY. A New Text-Book. Including- the 
 Signs and Symptoms of Pregnancy, Obstetric Operations, Diseases of 
 the Puerperal State, &c., &c. Second American from the Third Lon- 
 don Edition. Revised and Enlarged. With 145 Illustrations. $3-o 
 
 This book is especially valuable to the Student as containing in a condensed form a large 
 amount of valuable information on flle subject which it treats. It is also clear and methodi- 
 cal in its arrangement, and therefore useful as a work of reference for the practitioner. The 
 Illustrations are numerous and well executed. 
 
 MILLER (JAMES), F. R. C. S. 
 
 Professor of Surgery University of Edinburgh. 
 
 ALCOHOL, ITS PLACE AND POWER. From the Nineteenth 
 Glasgow Edition. 121110. Cloth flexible. Price . . . $0.50 
 
 This work was prepared by Professor Miller at the special request of the Scottish Temper- 
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 MILLER AND LIZARS. 
 
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 AND ABUSE OF TOBACCO. By JOHN LIZARS, late Professor to the 
 Royal College of Surgeons., &c. The Two Essays in One Volume. 
 I2mo. .... gi.oo 
 
25 
 
 MARSDEN (ALEXANDER), M.D. 
 
 A NEW AND SUCCESSFUL MODE OF TREATING CERTAIN 
 FORMS OF CANCER. Second Edition, Colored Plates. . $3.00 
 
 MACDONALD (j. D.), M. D., 
 
 Deputy Inspector-General of Hospitals, Assistant Professor of Hygiene, Army Medical School, &c. 
 
 A GUIDE TO THE MICROSCOPICAL EXAMINATION OF 
 DRINKING WATER. With Twenty Full-page Lithographic Plates, 
 References, Tables, etc., etc. Octavo. Price . . . $2.75 
 
 NORRIS (GEORGE w.), M. D., 
 
 Late Surgeon to the Pennsylvania Hospital, &c, 
 
 CONTRIBUTIONS TO PRACTICAL SURGERY, including 
 numerous Clinical Histories, Drawn from a Hospital Service of Thirty 
 Years. In one Volume, Octavo. Price . . . $4-oo 
 
 OTT (ISAAC), M. D., 
 
 Late Demonstrator of Experimental Physiology in the University of Pennsylvania! 
 
 THE ACTION OK MEDICINES. With Twenty-two Illustrations. 
 Octavo. Cloth. Price ....... $2.00 
 
 OGSTON (FRANCIS AND FRANCIS, JR.), M.D. 
 
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 PHYSICIAN'S VISITING LIST, PUBLISHED ANNUALLY. 
 
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 For 25 Patients weekly. Tucks, pockets, and pencil, . . . $1.00 
 
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 This Visiting List, now in its twenty-ninth year, contains the Metric or French Decimal 
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 POWER, HOLMES, ANSTIE, AND BARNES. 
 REPORTS ON THE PROGRESS OF MEDICINE AND SUR- 
 GERY, PHYSIOLOGY, OPHTHALMIC MEDICINE, MID- 
 WIFERY, DISEASES OF WOMEN AND- CHILDREN, MATERIA 
 MEDICA, &c. Edited for the Sydenham Society of London. Octavo. 
 Price "... $2.00 
 
26 
 PARKES (EDWARD A.), M. D., 
 
 Professor of Military Hygiene in the Army Medical School, &c, 
 
 A MANUAL OF PRACTICAL HYGIENE. The Eifth Revised 
 and Enlarged Edition, for Medical Officers of the Army, Civil Medical 
 Officers, Boards of Health, &c., &c. With many Illustrations. One 
 Volume Octavo. Price ....... $6.00 
 
 This work, previously unrivalled as a text-book for medical officers of the army, is now 
 equally unrivalled as a text-book for civil medical officers. The first book treats in succes- 
 sive chapters of water, air, ventilation, examination of air, food, quality, choice, and cooking 
 of tbod, beverages, and condiments ; soil, habitations, removal of excreta, warming of houses, 
 exercise, clothing, climate, meteorology, individual hygienic management, disposal of the 
 dead, the prevention of some common diseases, disinfection, and statistics. The second 
 book is devoted to the service of the soldier, but is hardly less instructive to the civil officer 
 of health. It is, in short, a comprehensive and trustworthy text-book of hygiene for the 
 scientific or general reader. London Lancet. 
 
 OSGOOD (HAMILTON), M. D., 
 
 Editorial Staff Boston M dical and Surgical J urnaL 
 
 WINTER AND ITS DANGERS. (Vol. V., American Health 
 Primers.) Cloth. Price ....... $0.50 
 
 PENNSYLVANIA HOSPITAL REPORTS. 
 
 EDITED BY A COMMITTEE OF THE HOSPITAL STAFF. 
 
 J. M. DA COSTA, M. D., and WILLIAM HUNT, M. D. Vols. i and 2 ; each 
 volume containing upwards of Twenty Original Articles, by former 
 and present Members of the Staff, now eminent in the Profession, with 
 Lithographic and other Illustrations. Price per volume . $2.00 
 
 The first Reports were so favorably received, on both sides of the Atlantic, that it is hardly 
 necessary to speak for them the universal welcome of which they are deserving. The papers 
 are all valuable contributions to the literature of medicine, reflecting great credit upon their 
 authors. The work is one of which the Pennsylvania Hospital may well be proud. It will 
 do much towards elevating the profession of this country. American Journal of Obstetrics. 
 
 PAGET (JAMES), F R. S., 
 
 Surgeon to St. Bartholomew's Hospital, &c. 
 
 SURGICAL PATHOLOGY. Lectures delivered at the Royal Col- 
 lege of Surgeons of England. Third London Edition, Edited and 
 Revised by WILLIAM TURNER, M. D. With Numerous Illustrations. 
 Price, in cloth, $7.00; in leather . . . . . $8.00 
 
 A new and revised edition of Mr. Paget's Classical Lectures needs no introduction to our 
 readers. Commends: tion would be as superfluous as criticism out of place. Every page bears 
 evidence that this edition has been " carefully revised." American Medical Journal. 
 
 PEREIRA (JONATHAN), M. D., F. R. S., &c. 
 PHYSICIAN'S PRESCRIPTION BOOK. Containing Lists of 
 
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 with Explanatory Notes, the Grammatical Constructions of Prescrip- 
 tions, Rules for the Pronunciation of Pharmaceutical Terms, a Proso- 
 diacal Vocabulary of the Names of Drugs, &c., and a Series of Abbre- 
 viated Prescriptions illustrating the use of the preceding terms, &c. ; to 
 which is added a Key, containing the Prescriptions in an unabbreviated 
 Form, with a Literal Translation, intended for the use of Medical and 
 Pharmaceutical Students. From the Fifteenth London Edition. Price, 
 in cloth, * i.oo ; in leather, with Tucks and Pocket, . . $1.25 
 
27 
 PARSONS (CHARLES), M. D., 
 
 Honorary Surgeon to the Dover Convalescent Homes, &c,, &c. 
 
 SEA-AIR AND SEA-BATHING. Their Influence on Health a 
 Practical Guide for the Use of Visitors at the Seaside. i8mo. $0.60 
 
 PARKER (LANGSTON), F. R. C. S. L. 
 
 THE MODERN TREATMENT OF SYPHILITIC DISEASES. 
 
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 with numerous Cases, Formulae, &c.,&c. Fifth Edition, Enlarged. $4.25 
 
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 PLASTIC AND ORTHOPEDIC SURGERY. Containing i. A 
 Report on the Condition of, and Advances made in, Plastic and Ortho- 
 pedic Surgery up to the Year 1871. 2. A New Classification and Brief 
 Exposition of Plastic Surgery. With numerous Illustrations. 3. Ortho- 
 pedics: A Systematic Work upon the Prevention and Cure of Deformities. 
 With numerous Illustrations. Octavo. Price $4. co 
 
 7r" T^ ^ 
 
 This is a good book upon an important practical subject; carefully written and abun- 
 dantly illustrated. It goes over the whole ground of deformities from cleft-palate and 
 club-foot to spinal curvatures and ununited fractures. It appears, moreover, to be an original 
 book. Medical and Surgical Reporter. 
 
 SAME AUTHOR. 
 GALVANO-THERAPEUTICS. A Revised reprint of A Report 
 
 made to the Illinois State Medical Society. With Illustrations. Price, 
 
 $1-25 
 
 PIESSE (G. w. SEPTIMUS), 
 
 Analytical Chemist. 
 
 WHOLE ART OF PERFUMERY. And the Methods of Obtaining 
 
 the Odors of Plants ; the Manufacture of Perfumes for the Handkerchief, 
 Scented Powders, Odorous Vinegars, Dentifrices, Pomatums, Cosmet- 
 ics, Perfumed Soaps, &c. ; the Preparation of Artificial Fruit Essences, 
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 trations. .......... 
 
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 COPPER MINING AND COPPER ORE. Containing a full Descrip- 
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28 
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 11 
 
29 
 
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30 
 
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31 
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32 
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33 
 
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34 
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35 
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37 
 
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AMERICAN HEALTH PRIMERS, 
 
 Edited by W. W. KEEN, M.D., 
 
 Fellow of the College Physicians, Philadelphia, Surgeon to St. Mary's Hospital, &c. 
 
 It is one of the chief merits of the Medical Profession in modern times that its members 
 are in the fore-front of every movement to prevent disease. It is due to them that the 
 Science of what has been happily called " Preventive Medicine " has its existence. Not only 
 in large cities, but in every town and hamlet, the Doctor leads in every effort to eradicate the 
 sources of disease. These efforts have been ably seconded by intelligent and public-spirited 
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 Association, with their manifold and most useful influences, are organizations which have 
 sprung from, and still further extend and reinforce, the efforts to improve the public health. 
 
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 they do, are ignorant of the facts of Anatomy, Physiology, and Hygiene, and of their prac- 
 tical application to the betterment of their health and the prevention of disease. Such 
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 laborious research and the highest skill. Accordingly, it is the object of this series of 
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 a knowledge of the elementary facts of Preventive Medicine, and the bearings and appli- 
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 They are not intended (save incidentally) to assist in curing disease, but to teach people 
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 The series is written from the American standpoint, and with especial reference to our 
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 materially from other nations. Sanitary Legislation especially, which in England has made 
 such notable progress, has barely begun with us, and it is hoped that the American Health 
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 especially in our large cities. 
 
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 that the text may be clearly and readily understood by any one heretofore entirely ignorant 
 of the structure and functions of the body. The authors have been selected with great 
 care, and on account of special fitness, each for his subject, by reason of its previous careful 
 study, either privately or as public teachers. 
 
 Dr. W. W. Keen has undertaken the supervision of the series as Editor, but it will be un- 
 derstood that he is not responsible for the statements or opinions of the individual authors. 
 
 Six VOLUMES are NOW READY, others are in Press 
 
 (By CHAS. H. BURNETT, M.D., of Philada., 
 
 turgeon in charge of Phila. Disp. for Diseases of 
 the Ear, Aurist to Presbyterian Hospital, etc. 
 
 II I nnn Lifp and How tn Rparh It / B yJ- G. RICHARDSON, M.D., of Philada., 
 
 II. LOng LITe, ana nOW TO neacn IT. j Prof, of Hygiene in University of Penna., etc. 
 
 mC A! r>nrl Co Br.4-1, : n ,i f By JOHN H. PACKARD, M.D., of Philada., 
 
 . Sea Air and Sea Bathing. { y si,- gt on to the Epical Hospital, etc. 
 
 (By JAMES C. WILSON, M.D., of Philada., 
 
 IV. The Summer and itS DiSeaSeS. \ Lecturer on Physical Diagnosis in Jefferson 
 
 ( Medical College, etc. 
 
 V Fvp^inht anH How tn Parp fnr It {By GEORGE c. HARLAN, M.D., of Phila., 
 v . tyesigni, ana now 10 uare Tor it. \ surgeon to the mils (Eye} Hospital. 
 
 f By J. SOLIS COHEN, M.D., of Philada., 
 VI. The ThPOat and the VOICe. \ Lecturer on Diseases of the Throat in Jefferson 
 
 * ( Medical College. 
 
 VII. The Winter and its Dangers. FSSFSSl. 2&$Sa 
 VIII. The Mouth and the Teeth. {^SSCSgf&S* 1 -' f PhUada " 
 
 IY flnt. Hnmoc /By HENRY HARTSHORNE, M.D., of Phila., 
 
 I A. UUP nuilieb. | Formerly Prof, of Hygiene in Univer. of Pcnna. 
 
 (By L. D. BULKLEY, M.D., of New York., 
 X. The Skin in Health and Disease.-^ Physician to the Skin Department of the DemiU 
 
 ( Dispensary and of the New York Hospital. 
 
 ( By H. C. WOOD, Jr., M.D., of Philada., 
 XI. Brain WOPk and Overwork. \ Clinical Professor of Nervous Diseases in the 
 
 (^ University of Pennsylvania, etc. 
 
 Other volumes are in preparation, including the following subjects: "Preventable 
 Diseases," " Accidents and Emergencies," " The Towns we Live In," " Diet 
 in Health and Disease," "The Art of Nursing," "School and Industrial 
 Hygiene," etc., etc. They will be l6mo in size, neatly printed on tinted paper, and 
 handsomely bound in embossed cloth. Price, 50 cents. 
 
 Mailed free upon receipt of price. 
 
 LINDSAY & BLAKISTON, Publishers, Philadelphia. 
 
 . Jy CHAS. H. BURNETT, M.D., of Philada., 
 I. Hearing, and HOW tO Keep It. \ Surgeon in charge of PhUa.Disp. for Diseases of 
 
Of