THE MALE URETHRA 453 



fibers of both sides meet, they unite to form a septum. This 

 septum is thick and complete behind, but in front many vertical 

 slits allow of communication between the two bodies, and have 

 given to the septum the name septum pcctiniforme. From the 

 inner surface of this envelope numerous fibrous trabeculae 

 pass in all directions. These trabeculse support and enclose 

 the arterial branches, which form a capillary network opening 

 directly into the cavernous spaces, some of them forming 

 convoluted vessels, the helicine arteries, which project into 

 the trabecular spaces. The blood is returned by the dorsal 

 vein, prostatic plexus, and pudenda! veins. 



The corpus sponyiosum commences behind, between the 

 two crura, and in front of the deep perineal fascia, as the 

 bulb, and in front expands to form the glans. The bulb receives 

 an investment from the anterior layer of the deep perineal 

 fascia and is surrounded by the accelerator urinse muscles. 

 The urethra runs through the upper part of the corpus spongio- 

 sum, surrounded by a layer of erectile tissue, the part within 

 the bulb being called the bulbous portion of the urethra. The 

 fibrous envelope is white, thinner than that of the corpora 

 cavernosa, and encloses a similar trabecular structure. Just 

 beneath it, forming part of the outer coat, is a layer of muscular 

 fibers, and a second muscular layer lies beneath the urethral 

 mucous membrane. 



THE MALE URETHRA 



The male urethra extends from the neck of the bladder to 

 the end of the penis, is about 8 J inches long, and is lined through- 

 out by mucous membrane supported by a submucous tissue 

 and connected by it with the subjacent tissues in its three 

 parts, viz., the prostatic, membranous, and spongy. Part 

 of the submucous tissue is composed of a longitudinal muscular 

 layer internally and a circular externally. 



The prostatic portion is the widest part of the canal, and 

 traverses the prostate gland, being about If inches long, 

 widest at the middle, and lying above the middle lobe. It 

 is very dilatable. On its floor is a slight longitudinal elevation 

 at the back part, which passes back to the uvula vesicse, and 

 is placed in the median line, measuring f inch long and about 

 \ inch at its maximum height. This ridge has been variously 



