164 ABDOMEN 



the dorsal artery of the penis, and the deep artery of the 

 penis. 



The bulb of the urethra causes the projecting rounded 

 eminence which occupies the median part of the superficial 

 perineal pouch. It is covered by the bulbo-cavernosus 

 muscle. Each crus penis lies along the corresponding lateral 

 margin of the superficial pouch, and it is covered by the ischio- 

 cavernosus muscle. The superficial transverse muscle passes 

 forwards and medially from the posterior end of the crus 

 penis to the central point of the perineum, which lies immedi- 

 ately behind the posterior end of the bulb of the urethra. 



Dissection. Divide the scrotal nerves and the accompanying 

 arteries near their terminal extremities and turn them aside ; 

 then, with the handle of the scalpel, enlarge the interval between 

 the bulb of the urethra, covered by the bulbo-cavernosu's, medially, 

 the crus of the penis, covered by the ischio-cavernosus, laterally, 

 and the superficial transverse muscle posteriorly. The membrane 

 which forms the deep boundary of the triangular area thus dis- 

 played is the inferior fascia of the urogenital diaphragm. 



Only the lower part of the diaphragm is obvious at this stage 

 of the dissection, but the dissector must consider the structure 

 and the general positions and relations of the diaphragm before 

 proceeding further with the dissection. 



Urogenital Diaphragm. Only the superficial surface of 

 the inferior fascia of the urogenital diaphragm is as yet 

 exposed, but it is necessary, before the dissection is carried 

 further and the diaphragm is partially destroyed, that the dis- 

 sectors should have a general knowledge of its various parts, 

 so that they may understand the relations of the diaphragm 

 to the other structures which lie in the anterior part of the 

 perineum. The urogenital diaphragm is a strong, triangular 

 partition which stretches across the pubic arch and separates 

 the anterior part of the perineum from the pelvis. It consists 

 of the deep transverse muscle of the perineum, and the 

 sphincter urethras membranaceae, enclosed between two layers 

 of fascia, an upper and a lower. The two layers of fascia are 

 blended together anteriorly and posteriorly. They are attached 

 laterally to the margins of the pubic arch, and they enclose 

 between them a space which contains not only the muscular 

 part of the diaphragm but also the membranous portion of 

 the urethra, the bulbo-urethral glands (O.T. Cowper's), the 

 terminal parts of the internal pudendal vessels and some of 

 their branches, and the dorsal nerves of the penis. The 

 blended anterior margins of the inferior fascia of the urogenital 



