1006 THE URINARY ORGANS. 



verumontanum. At the fore part of the verumontanum, in the middle line, is a 

 depression, the sinus pocularis (vesicula prostatica) ; and upon or within its mar- 

 gins 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 upward and back- 

 ward in the substance of the prostate behind the middle lobe ; its prominent ante- 

 rior wall partly forms the verumontanum. Its walls are composed of fibrous tissue, 

 muscular fibres, and mucous membrane, and numerous small glands open on its 

 inner surface. It has been called by Weber, who discovered it, the uterus mascu- 

 linus, from its being developed from the united lower ends of the atrophied 

 Miillerian ducts, and therefore homologous with the uterus and vagina in the 

 female. 



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 meatus), and measures three-quarters of an inch along its upper, 

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

 backward beneath it. Its anterior concave surface is placed about an inch below 

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

 nerves of the penis, and some muscular fibres. Its posterior convex surface is 

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

 The membranous portion of the urethra lies between the inferior and superior 

 layers of the triangular ligament. As it pierces the inferior layer, the fibres 

 around the opening are prolonged over the tube. It is also surrounded by the 

 Compressor urethras muscle. 



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 ter- 

 mination of the membranous portion of the meatus urinarius. Commencing just 

 below the triangular ligament, it inclines downward for a short distance; it next 

 ascends for about half its length, c.nd then, in the flaccid condition of the penis, 

 it bends suddenly downward. 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 ; and again anteriorly within the glans penis, where it forms the 

 fossa navicularis. 



The Bulbous portion is a name given, in some descriptions of the urethra, to 

 the posterior part of the spongy portion contained within the bulb. 



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 forward, so that they may easily intercept the 

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

 the rest, is situated in the upper surface of the fossa navicularis, about an inch and 

 a half from the orifice ; it is called the lacuna niagna. Into the bulbous portion 

 are found opening the ducts of Cowper's glands. 



Structure. The urethra is composed of a continuous mucous membrane, 

 supported by a submucous tissue which connects it with the various structures 

 through which it passes. 



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 glands which open into the urethra viz. Cowper's glands and the 

 prostate gland and into the vasa deferentia and vesiculae seminales through the 

 ejaculatory ducts. In the spongy and membranous portions the mucous membrane 

 is arranged in longitudinal folds when the tube is empty. Small papillae are found 

 upon it near the orifice, and its epithelial lining is of the columnar variety, except- 

 ing near the meatus, where it is squamous. 



The submucous tissue consists of a vascular erectile layer, outside which is a 





