URETHRA. 733 



or caput yallinaginis, formed by an elevation of the mucous membrane and its. 

 subjacent tissue. It is eight or nine lines in length, and a line and a half in 

 height, and contains, according to Kobelt, muscular and erectile tissues. When 

 distended, it may serve to prevent the passage of the semen backwards into the 

 bladder. On each side of the veru montanum is a slightly depressed fossa, the 

 prostatic sinus, the floor of which is perforated by numerous apertures, the orifices 

 of the prostatic ducts, the ducts of the middle lobe opening behind the crest. At 

 the fore part of the veru montanum, in the middle line, is a depression, the sinus 

 pocularis or vesicula prostalica; and upon or within its margins are the slit-like 

 openings of the ejaculatory ducts. The sinus pocularis forms a cul-de-sac about 

 a quarter of an inch in length, which runs upwards and backwards in the sub- 

 stance of the prostate, beneath the middle lobe ; its prominent upper wall partly 

 forms the veru montanum. Its walls are composed of fibrous tissue, muscular 

 fibres, and mucous membrane ; and numerous small glands open on its inner sur- 

 face. It has been called by Weber, who discovered it, the uterus masculinus, 

 from its supposed homology with the female organ. 



The Membranous portion of the urethra extends between the apex of the pros- 

 tate, and the bulb of the corpus spongiosum. It is the narrowest part of the canal 

 (excepting the orifice), and measures three-quarters of an inch along its upper, 

 and half an inch along its lower surface, in consequence of the bulb projecting 

 backwards beneath it below. Its upper concave surface is placed about an inch 

 beneath the pubic arch, from which it is separated by the dorsal vessels and nerves 

 of the penis, and some muscular fibres. Its lower convex surface is separated 

 from the rectum by a triangular space, which constitutes the perineum. The 

 membranous portion of the urethra perforates the deep perineal fascia ; and two 

 layers from this membrane are prolonged round it, the one forwards, the other 

 backwards ; it is also surrounded by the Compressor urethra muscle. Its cover- 

 ings are mucous membrane, elastic fibrous tissue, a thin layer of erectile tissue, 

 muscular fibres, and a prolongation from the deep perineal fascia. 



The Spongy portion is the longest part of the urethra, and is contained in the 

 corpus spongiosum. It is about six inches in length, and extends from the termi- 

 nation of the membranous portion to the meatus urinarius. Commencing below 

 the symphysis pubis, it ascends for a short distance, and then curves downwards. 

 It is narrow, and of uniform size in the body of the penis, measuring about a 

 quarter of an inch in diameter ; being dilated behind, within the bulb, where it 

 forms the bulbous portion, and again anteriorly, within the glans penis, forming 

 the fossa navicularis. A cross section of this canal in the body has its diameter 

 transverse, but in the glans the diameter is directed vertically. 



The meatus urinarius is the most contracted part of the urethra ; it is a vertical 

 slit, about three lines in length, bounded on each side by two small labia. The 

 inner surface of the lining membrane of the urethra, especially on the floor of the 

 spongy portion, presents the orifices of numerous mucous glands and follicles, 

 situated in the submucous tissue, and named the glands of Littre. They vary in 

 size, and their orifices are directed forwards, so that they may easily intercept the 

 point of a catheter in its passage along the canal. One of these lacuna, larger 

 than the rest, is situated on the upper surface of the fossa navicularis, about an 

 inch and a half from the orifice ; it is called the lacuna mayna. Into the bulbous 

 portion are found opening the ducts of Cowper's glands. 



Structure. The urethra is composed of three coats : a mucous, muscular, and 

 erectile. 



The mucous coat forms part of the genito-urinary mucous membrane. It is 

 continuous with the mucous membrane of the bladder, ureters, and kidneys, 

 externally, with the integument covering the glans penis ; and is prolonged into 

 the ducts of the numerous glands which open into the urethra, viz., Cowper's 

 glands, and the prostate gland ; and, through the ejaculatory ducts, is continued into 

 the vasa deferentia and vesiculas seminales. In the spongy and membranous 

 portions, the mucous membrane is arranged in longitudinal folds when the organ 



