540 A MANUAL OF ANATOMY. 



riorly, prostate, seminal vessels, urethra, rectovesical fascia, 

 venous plexuses. 



The External Trig-one. Fig. 84. This is a triangular sur- 

 face on the posterior wall of the bladder bounded at the apex 

 by the prostate, on the sides by the diverging seminal vesi- 

 cles and the vas deferens, and above by the reflection of the 

 peritoneum from the posterior wall of the bladder to the 

 front of the rectum. This fold is from one to one and one- 

 half inches from the prostate and three and one-half inches 

 from the anus. 



This surface of the bladder is in close relation to the 

 rectum and only separated from it by some rectovesical 

 fascia. Through this space a trocar might be introduced 

 from the rectum into the bladder, though it is not practiced 

 now. 



The Ureter. Figs. 103 to 107, 112. 



This is a small canal (one-sixteenth of an inch in diameter), 

 which extends from the kidney to the bladder, carrying the 

 urine from the former to the latter. Its average length is 

 twelve to sixteen inches. It lies behind the peritoneum and 

 is enclosed in the extraperitoneal tissue. 



After crossing the psoas muscle and the iliac vessels it 

 passes to the lateroposterior wall of the bladder, curves down- 

 ward and inward to enter the substance of the bladder in 

 front of the upper end of the seminal vessels ; after travers- 

 ing the bladder wall they open upon its inner surface about 

 three -fourths of an inch apart and the same distance pos- 

 terior to the internal opening of the urethra. In the male 

 the vas deferens passes between the ureter and bladder. In 

 the female, the ureter runs in front of the cervix uteri and 

 upper part of the vagina (between these and the bladder). 

 At the base of the bladder, where the ureters are entering 



