THE URETHRA 379 



urethrae (corpus spongiosum). This part of the tube is fixed 

 in position, but the cavernous (spongy) part of the urethra, 

 situated within the body of the penis, is freely movable. It 

 is in the most dependent part of the urethra that organisms 

 tend to settle down, and consequently gonorrhoeal stricture 

 commonly occurs within the bulb of the penis. 



The prostatic portion of the urethra (Fig. 127) is the 

 most dilatable part of the canal. A longitudinal elevation, 

 termed the urethral crest^ is present on its dorsal wall (or 

 floor) and the groove on each side of it receives the openings 

 of the prostatic ducts. Gonorrhoeal inflammation may pass 

 backwards into the prostatic urethra, and, if it affects the 

 prostatic duct, a troublesome chronic gleet will supervene. 

 At the anterior end of the urethral crest, there is a small 

 opening in the floor of the urethra. It leads into a short, 

 blind diverticulum, termed the prostatic utricle (sinus pocularis\ 

 which is all that exists in the male as the homologue of the 

 uterus and vagina (Fig. 131). At or near the orifice of the 

 prostatic utricle, the ejaculatory ducts open into the prostatic 

 urethra. They may be infected in posterior urethritis and lead 

 to inflammation of the seminal vesicles or of the epididymis. 



The membranous part of the urethra lies between the two 

 layers of fascia of the urogenital diaphragm (the two layers of 

 the triangular ligament). It is only half an inch long (Fig. 

 127), but it is of importance because a false passage may be 

 made with a bougie, in endeavouring to pass the instrument 

 from the cavernous (spongy) part into the membranous 

 urethra. 



The cavernous (spongy) portion of the urethra is 6 to 8 

 inches long. It is narrowest at the external orifice on the 

 surface of the glans and is widest within the substance of the 

 glans. A vesical calculus may be passed along the urethra 

 and be unable to pass through its external orifice. 



The deep surface of the prepuce consists of modified skin 

 and the surface of the glans possesses a similar covering. 

 Normally, after the development of the prepuce is complete, 



