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URINARY ORGANS. 



Fig. 437. The bladder and Urethra 

 laid open. "Seen from above. 



correspond with the muscles of these tubes ; and at each posterior angle, by the 

 orifices of the ureters, which are placed nearly two inches from each other, and 

 about an inch and a. half behind the orifice of the urethra. The trigone cor- 

 responds with the interval at the base of the bladder, bounded by the^prostate 



in front, and the vesiculae and vasa deferentia 

 on the sides. Projecting from the lower and 

 anterior part of the bladder, into the orifice of 

 the urethra, is a slight elevation of mucous 

 membrane, called the uvula vesicae. It is formed 

 by a thicken'ing of the prostate. 



The arteries supplying the bladder are the 

 superior, middle, and inferior vesical, in the 

 male, with additional branches from the uterine, 

 in the female. They are all derived from the 

 anterior trunk of the internal iliac. 



The veins form a complicated plexus round 

 the neck, sides, and base of the bladder, and 

 terminate in the internal iliac vein. 



The lymphatics accompany the bloodvessels, 

 passing through the glands surrounding them. 



The nerves are derived from the hypogastric 

 and sacral plexuses; the former supplying the 

 upper part of the organ, the latter its base and 

 neck. 



MALE UKETHRA. 



The Urethra extends from the neck of the 

 bladder to the meatus urinarius. It presents a 

 double curve in the flaccid state of the penis, 

 but in the erect state it forms only a single 

 curve, the concavity of which is directed up- 

 wards (Fig. 436). Its length varies from eight 

 to nine inches ; and it is divided into three por- 

 tions, the prostatic, membranous, and spongy 

 the structure and relations of which are essen 

 tially different. 



The prostatic portion is the widest and most 

 dilatable part of the canal. It passes through 

 the prostate gland, from its base to its apex, 

 lying nearer its upper than its lower surface. 

 It is about an inch and a quarter in length ; 

 the form of the canal is spindle-shaped, being 



wider in the middle than at either extremity, and narrowest in front, where 

 it joins the membranous portion. A transverse section of the canal in this 

 situation is triangular, the apex directed downwards. 



Upon the floor of the canal is a narrow longitudinal ridge, the verumontanuin, 

 or caput gallinayinis, 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 th 

 bladder. On each side of the verumontanum is a slightly depressed fossa, th 

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

 orifices of the prostatic ducts, the ducts of the middle lobe opening behind th 

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

 sion, the sinus pocular is (vesicula prostatica}; and upon or within its margins are 

 the slit-like openings of the ejaculatory ducts. The sinus pocularis forms a 



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