THE URINARY BLADDER 449 



THE URINARY BLADDER (VESICA URINARIS) 



The bladder is situated in the pelvic cavity, but in infancy 

 and when distended in the adult, extends into the hypogastrium. 

 It measures when moderately distended 5 to 5j inches in 

 length, 4| in width, and 3 inches from before backward. It 

 holds a pint of urine without discomfort. The bladder presents 

 a superior, anteroinferior, and two lateral surfaces; a base or 

 fundus, and an apex, or summit. 



The interior of the bladder shows the mucous membrane 

 thrown into rugae, the orifices of the ureters, and the trigone. 

 The ureteral orifices are about 2 inches apart, when the bladder 

 is moderately distended. The trigone, or trigonum vesical, is a 

 smooth, triangular surface, paler than the rest of the mucous 

 membrane. It is bounded at the basal angles to the orifices 

 of the ureters, and the apex to the urethral orifice. The ureteral 

 folds are the prolongations extending beyond the ureteral 

 orifices, of the transverse ureteral fold containing muscle 

 fibers covered by the mucous membrane. The urethral open- 

 ings are surrounded by a circular fold of mucous membrane, 

 called the annulus urethralis. 



The ligaments of the bladder are true and false. The true 

 are the two anterior, two lateral, and the urachus. The false 

 are five, and consist of folds of peritoneum. 



The two anterior true or puboprostatic ligaments extend from 

 back of the pubic bone, one on each side of the symphysis, 

 to the front of the neck of the bladder, over the anterior 

 surface of the prostate gland. The two lateral true ligaments 

 arise from the pelvic wall, being formed by the pelvic fascia, 

 (rectovesical fascia), and are inserted into the sides of the 

 base of the bladder and the lateral surfaces of the prostate 

 gland. The urachus is the impervious remains of the allantois, 

 an embryological structure, which helped to form the bladder. 

 It is attached to the apex of the bladder and passes to the 

 umbilicus, between the transversalis fascia and peritoneum, 

 forming the plica umbilicalis media. The two posterior false 

 ligaments are folds of peritoneum, passing from the sides 

 of the rectum, in the male to the outer and posterior aspect 

 of the bladder (the rectovesical folds); in the female these 

 folds are called (the vesicouterine folds) and pass from the 

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