THE PERINEUM PROPER IN THE MALE. 



1067 



round the anterior free edge of this muscle with the recto-vesical layer covering 

 the prostate gland. The superior layer of the triangular ligament is perforated 

 by the urethra. Between the two layers of the triangular ligament are situated 

 the membranous part of the urethra, enveloped by the Compressor urethrae muscle ; 

 the ducts of Cowper's glands ; the arteries to the bulb; the pudic vessels and the 

 dorsal nerve of the penis. The membranous part of the urethra is about three- 

 quarters of an inch in length, and passes downward and forward behind the 

 symphysis pubis, from which it is distant about an inch. It is the narrowest part 

 of the tube, and is enveloped, as has already been stated, by the Compressor 

 urethrae muscle. 



The Compressor urethrse has already been described (page 374). In addition to 

 this muscle and immediately beneath it circular muscular fibres surround the mem- 

 branous portion of the urethra from the bulb in front to the prostate behind, and are 

 continuous with the muscular fibres of the bladder. These fibres are involuntary. 



Cowper's glands are situated immediately below the membranous portion of 

 the urethra, close behind the bulb, and below the artery of the bulb. 



Anterior layer of 



deep perineal fascia removed, 



showing 



^COMPRESSOR URETHR>E. 



Internal pudic artery. 

 Artery of the bulb. 

 Cowper's gland. 



FIG. 592. Deep perinea! fascia. On the left side the anterior layer has been removed. 



The pudic vessels and dorsal nerve of the penis are placed along the inner mar- 

 gin of the pubic arch (pages 565 and 793). 



The artery of the bulb passes transversely inward, from the internal pudic 

 along the base of the triangular ligament, between its two layers, accompanied by 

 a branch of the pudic nerve (page 567). If the deep layer of the triangular 

 ligament 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 369). 



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

 of the perinaenm, 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 

 vcsiculae seminales. and the vasa deferentia will be exposed. 



