THE ABDOMEN 923 



marked depression, occapied by fat, is to be shown. To facilitate this dis- 

 section, the pelvic brim may be removed on one side. 



The prostate gland is now to be exposed, and the anterior fibres of the 

 levator ani shown on its side. Within its fascicd sheath wiU be found the 

 prostatic venous plexus, which receives the dorsal vein of the penis in two 

 divisions. If the subject is a female, a portion of the vagina is to be shown. 

 The ureter, vas deferens, and obliterated hypogastric artery are to be dis- 

 played, and their relations noted. The ureter will be found on the lateral wall 

 of the pelvis in front of the internal iliac arterj', and, as it curves inwards to the 

 lateral angle of the bladder, it will be seen to be crossed by the vas deferens. 

 In the female, before reaching the bladder, it should be shown to he on the side 

 of the extravaginal portion of the cervix uteri, and for a short distance on the 

 lateral waU of the vagina at its upper part. The obUterated hv-pogastric 

 artery wiU be found passing forwards from the anterior division of the internal 

 iliac artery over the lateral waU of the pelvis towards the apex of the bladder. 

 Thereafter the internal iliac artery and its branches are to be dissected, as 

 follows : from the anterior division, the pervious portion of the obUterated 

 hypogastric, giving off two or three superior vesical arteries ; inferior vesical, 

 usuaUj' gi\'ing off middle hemorrhoidal ; obturator ; internal pudic ; and 

 sciatic ; and, from the posterior division, the iUo-lumbar ; two or three 

 lateral sacral ; and gluteal. The special branches in the female are the 

 uterine and vaginal arteries. The arteries are accompanied by offshoots 

 from the pelvic sympathetic plexus. 



In dissecting the branches of the artery, care is to be taken of the nerves 

 which arise from the sacral plexus. By displacing the viscera, this plexus 

 and its branches are to be dissected, including the lumbo-sacral cord. In 

 dissecting the plexus, the nerves which form the lumbo-sacral cord, the 

 cord itself, and the first two sacral nerves are to be shown, by careful 

 dissection, in two divisions, ventral and dorsal, and the third sacral 

 (nervus bigeminus) is to be shown dividing into an upper and a lower branch. 

 The fourth sacral is a nervus furcaUs. The sciatic and pudic bands of the 

 plexus are to be displayed. The branches will be found to arise as follows : 

 superior gluteal, by three roots from the dorsal divisions of the descending 

 branch of the fourth lumbar, the fifth lumbar, and the first sacral ; inferior 

 gluteal, by three roots from the dorsal di\'isions of the fifth lumbar, and first 

 and second sacral ; muscular branches to the pyriformis, from the dorsal 

 divisions of the first and second sacral ; nerve to the obturator intemus and 

 gemellus superior, by three roots from the ventral divisions of the fifth lumbar, 

 and first and second sacral ; nerve to quadratus femoris and gemellus inferior, 

 from the ventral divisions of the descending branch of the fourth lumbar, fifth 

 lumbar, and first sacral ; visceral branches to the bladder, from the third and 

 part of the fourth sacral ; small sciatic, by three roots from the posterior aspect 

 of the first, second, and third sacral ; perforating cutaneous, by two roots 

 from the posterior aspect of the second and third sacral ; great sciatic, which 

 is the continuation of the upper or sciatic band of the plexus ; and pudic, 

 which is the continuation of the lower or pudic band. The sacro-coccygeal 

 plexus, formed by part of the fourth sacral, fifth sacral, and coccygeal nerves, 

 is to be dissected, and the pelvic sympathetic cord is to be displayed with 

 the ganglion impar on the first coccygeal vertebra. The middle and lateral 

 sacral arteries are to be followed out, and an effort should be made to show 

 the coccygeal gland of Luschka near the tip of the coccyx. Branches of the 

 middle sacral artery may help to guide the dissector to it. The pyriformis, 

 levator ani, and coccygeus muscles are to be dissected, and the relation of 

 the latter two to the pelvic floor is to be noted. The obturator intemus is 

 also to be studied. 



Viscera of the Pelvis. — The position of the rectum, and its relations to the 

 bladder and prostate gland in the male, and uterus and vagina in the female, 

 having been studied as far as possible in situ, the viscera are to be removed 

 en masse along with the superior hemorrhoidal vessels. The bladder, if empty, 

 should be partially inflated, and the rectum and anal canal slightly distended 

 with tow, as well as the vagina.if the subject is a female. The relations of the 



