UROGENITAL SYSTEM. 



root of the mesentery. It then descends on the pelvic wall in 

 front of the internal iliac artery to the level of the ischial spine, 

 crossing the obturator vessels and nerve and the obliterated 

 hypogastric artery. Then bending inward under the vas def- 

 erens, it passes in front of the upper end of the seminal vesi- 

 cles, reaching the bladder in front of the vas, two inches from 

 the other ureter, and piercing the wall obliquely. In the female 

 it accompanies the uterine artery along the outer side of the 

 cen'x and upper part of the vagina. [1141] 



Bladder. This lies in front of the pelvis, its size and shape 

 depending on its distention. The lower portion rests on the 

 pelvic floor and is but slightly movable. At its lowest part, 

 in an apparently constricted neck or cervix, is the internal 

 urethral orifice, which lies about two inches behind and slightly 

 below the upper border of the symphysis in the male, some- 

 what lower in the female. The base, or postero-interior surface, 

 is a triangular area looking downward and backward, and ly- 

 ing behind the urethral orifice. The rest of the under aspect 

 of the lower portion consists of two more triangular areas 

 (infer o-lateral) , which are directed downward and outward but 

 meet in the midline in front of the urethral orifice. These three 

 areas are separated by three rounded borders, one extending 

 from the urethral orifice to the bladder apex, and two to the 

 points where the ureters reach the bladder. The apex, or sum- 

 mit, is the part of the empty, or slightly filled, bladder lying 

 nearest the upper border of the symphysis; a fibrous cord 

 (urachus) runs from it to the umbilicus. The part between the 

 apex and base is the body of the bladder. [1144] 



When empty the bladder has the shape of an inverted tetra- 

 hedron, its apex lying at the urethral orifice, and its base being 

 formed by the superior surface, which is triangular and looks 

 upward. The basal angles correspond to the apex of the blad- 

 der and the lateral angles, or points where the ureters join it; 

 the posterior border connects the lateral angles; the lateral 

 borders extend from the bladder apex to the lateral angles. 



[233] 



