1206 



SURGICAL ANATOMY OF THE PERINEUM. 



accompanied by a branch of the pudic nerve (page 861). If the posterior layer of 

 the deep perineal fascia is removed and the crus penis of one side detached from 

 the bone, the under or perineal surface of the Levator ani is brought fully into 

 view. This muscle, with the triangular ligament in front and the Coccygeus and 

 Pyriformis behind, closes the outlet of the pelvis. 



The Levator ani and Coccygeus muscles have already been described (page 459). 



Position of the Viscera at the Outlet of the Pelvis. Divide the central tendinous point 

 of the perinseum, separate the rectum from its connections by dividing the fibres of the Levator 

 ani, which descend upon the sides of the prostate gland, and draw the gut backward toward the 

 coccyx, when the under surface of the prostate gland, the neck and base of the bladder, the 

 vesiculse seminales, and the vasa deferentia will be exposed. 



The Prostate Gland is a pale, firm, glandular body which is placed immediately 

 in front of the neck of the bladder around the commencement of the urethra. It is 



Artery of corpus cavernosum 

 Dorsal artery of penis 



Artery of bulb. 

 Internal pudic artery. 



Cowper's gland. 



FIG. 770. A view of the position of the viscera at the outlet of the pelvis. 



placed in the pelvic cavity, behind and below the symphysis pubis, posterior to the 

 deep perineal fascia, and rests upon the rectum, through which it may be distinctly 

 felt, especially when enlarged. In shape and size it resembles a chestnut. Its 

 base is directed backward toward the neck of the bladder. Its apex is directed 

 forward to the deep perineal fascia, which it touches. 



Its posterior surface is smooth, marked by a slight longitudinal furrow, and rests 

 on the rectum, to which it is connected by areolar tissue. Its anterior surface is 

 flattened, marked by a slight longitudinal furrow, and placed about three-quarters 

 of an inch below the pubic symphysis. It measures about an inch and a half in 

 its transverse diameter at the base, an inch in its antero-posterior diameter, and 

 three-quarters of an inch in depth. Hence the greatest extent of incision that can 

 be made in it without dividing its substance completely across is obliquely back- 

 ward and outward. This is the direction in which the incision is made in it in 

 the lateral operation of lithotomy. 



Behind the prostate is the posterior surface of the neck and base of the bladder, 

 a small triangular portion of the bladder being seen, bounded, in front, by the 

 prostate gland ; behind, by the recto-vesical fold of the peritoneum ; on each side, 

 by the vesicula seminalis and the vas deferens. It is separated from direct contact 



