160 THE ABDOMEN. 



pelvic cavity, but before describing the pelvis itself it 

 will be well to complete the account of the urinary or- 

 gans by considering the bladder and urethra. The 

 bladder is the reservoir for the urine and has muscular 

 walls lined with mucous membrane. A peritoneal coat 

 covers the upper surface and is reflected to the walls of 

 the abdomen and pelvis. It is situated back of the os 

 pubis, the front bone of the pelvis, with its base or 

 fundus directed downward and backward. Normally it 

 is in the pelvis, but when much distended it mounds up 

 into the abdominal cavity, where it can be felt in front 

 as a tumor. It rests on the rectum in the male and on 

 the cervix in the female and is held in place by numer- 

 ous ligaments. When empty it may be Y-shaped, but 

 it becomes oval when distended. Its capacity is about 

 one pint. 



The lower abdominal wall and the anterior wall of 

 the bladder may be wanting congenitally. In paralysis 

 of the sphincter at the neck of the bladder distention 

 results. Stones may be found in the bladder. 



From the neck of the bladder the urine passes out of 

 the body through the urethra. This in the male passes 

 down through the. penis and is about ten inches long. 

 Except when urine is passing it is a transverse slit with 

 the upper and under surfaces in contact, while at the 

 end of the penis the slit of the meatus urinarius is vertical. 

 When the penis is flaccid, the urethra describes a sharp 

 curve before its entrance into the bladder, but it be- 

 comes approximately straight when the penis is raised 

 at right angles to the body an important point to re- 

 member in catheterization. 



In the female the urethra is straight and much shorter, 

 being only about one and a half inches long. The 

 meatus urinarius is in the anterior vaginal wall about 

 one inch behind the clitoris. 



Sometimes the urethra is ruptured in a fall. Strict- 

 ure of the urethra occurs sometimes after gonorrhoea, 

 owing to the formation of scar tissue following ulcer. 



