732 



URINARY ORGANS. 



Fig. 370. The Bladder and Urethra laid open. 

 Seen from above. 



of which is directed forwards; this is the trigonum vesicse or trig one vesicale. It 

 .s paler in color than the rest of the mucous membrane, and never presents any 

 rugae, even in the collapsed condition of the organ, owing to its intimate adhesion 

 to the subjacent tissues. It is bounded on each side by two slight ridges, which 

 pass backwards and outwards to the orifices of the ureters, and 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 corresponds with the 



interval at the base of the bladder, 

 bounded by the prostate in front, and 

 the vesiculoa 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 vesicse. It is formed by a 

 thickening 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 veins. 



The lymphatics accompany 

 bloodvessels, passing through 

 glands surrounding them. 



The nerves are derived from the 

 typggastric and sacral plexuses; the 

 former supplying the upper part of 

 the organ, the latter its base and 

 neck. 



MALE URETHRA. 



The Urethra extends from the neck 

 of the bladder to the meatus urinarius. 

 It is curved in its course, so as to 

 resemble, in its flaccid state, the Italic 

 letter /; but in the erect state it forms 

 only a single curve, the concavity of 

 which is directed upwards. Its length 

 varies from eight to nine inches ; and 

 it is divided into three portions, the 

 prostatic, membranous, and spongy, 

 the structure and relations of which 

 are essentially 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, and 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 veru montanum 



