THE URETHRA 



247 



lower part is the base or fundus. There are three openings in the 

 bladder wall, two for the entrance of urine and one for expelling it. 



The urine enters through the two ureters (Fig. 162) or ducts 

 of the kidney, which, having reached the pelvis, proceed below 

 the broad ligaments (Fig. 138)) to run forward and enter the base 

 of the bladder, there discharging the urine. 



The opening for the escape of the urine is called the internal 



Bladder Uterus 



Urethra 



Vaginal 

 orifice 



Anus (rectum distended) 



FIG. 165. PELVIC ORGANS, FEMALE PELVIS. (Holden.) 

 Dotted lines indicate peritoneum. 



orifice. It leads into a canal called the urethra which ends at the 

 external orifice (or meatus), and through it the urine is expelled 

 from the body. The internal orifice is guarded by circular muscle 

 fibers forming a sphincter the sphincter vesica (sphincter of the 

 bladder). The part where the internal orifice is located is often 

 called the neck of the bladder. 



The openings of the ureters are about one inch from the internal 

 orifice, and the same distance apart, thus these three openings 

 mark the corners of a triangle at the base of the bladder, called 

 the trigone. 



The urethra is a fibro-muscular canal lined with mucous mem- 

 brane. It begins at the internal orifice of the bladder, ends at the 

 external orifice or meatus urinarius, and conducts the urine from 

 the body. 



