506 DISSECTION OF THE PELVIS. 



bulb of the corpus spongiosum urethrae ; but as the gut recedes from the 

 urethra there is an angular interval left between them. The levatores ani 

 muscles descend on its sides, and unite beneath it, supporting it in a sling; 

 and the sphincter muscles surround the aperture. Sometimes the end of 

 the intestine within the anus is very much enlarged, especially in women 

 and old men ; and in that condition in the male it rises up on each side of 

 the prostate. 



The URINARY BLADDER (vesica urinaria) is situate in the fore part of 

 the pelvis (fig. 174, a), and is the receptacle for the fluid secreted by the 

 kidneys. 



When the bladder is contracted it is flattened, and of a triangular form, 

 and lies against the anterior wall of the pelvis ; but when distended it be- 

 comes of a conical shape, with the larger part towards the rectum, and 

 the apex to the abdominal wall. In distension during life it is slightly 

 curved over the anterior part of the pelvis, as it projects above the bone ; 

 and if a line through its centre were prolonged, it would touch anteriorly 

 the abdominal wall somewhere (according to the distension) between the 

 umbilicus and the pubes, and posteriorly the end of the sacrum or the 

 coccyx. 



The position and form of the bladder are not the same in early life as 

 in the adult. For in the child this viscus rises above the brim of the 

 pelvis into the hypogastric region of the abdomen, and the cervix is the 

 lowest part. But in the adult the bladder is contained within the space 

 inclosed by the pelvic bones, and the base projects inferiorly. 



The organ is maintained in position by the recto-vesical fascia and the 

 peritoneum, which form its ligaments (pp. 502 and 504). The connec- 

 tions of the bladder moderately full are the following : 



The summit or apex is rounded, and from its anterior part three liga- 

 mentous cords are prolonged to the umbilicus ; the central one of these is 

 the remains of the urachus; and the two lateral are formed by the oblite- 

 rated hypogastric arteries. If the bladder is distended the apex is above, 

 but otherwise below the pubes. All the surface behind fhe obliterated 

 vessels is covered by peritoneum. 



The base (fundus) is large, and rests on the middle piece of the rectum : 

 in the state of emptiness of the bladder the base is scarcely prominent, 

 but in distension of the viscus, it extends lower, and becomes widened. 

 Connected with the fundus are the vesiculae seminales and the vasa defe- 

 rentia; and between these is a triangular space, from which the perito- 

 neum is partly absent. 



Surfaces of the body. The front of the body is in contact with the 

 posterior surface of the symphysis pubis, and with the abdominal wall if it 

 is distended, and is altogether free from peritoneum ; whilst the posterior 

 surface is entirely covered by the serous membrane, and is touched often 

 by the small intestine. 



Extending along the upper part of each lateral region is the obliterated 

 hypogastric vessel ; and running down behind this is the vas deferens, 

 which passes internal to the ureter. Near the under part the ureter enters 

 the bladder. All the side of the bladder behind the hypogastric vessel is 

 covered by peritoneum, but the rest is uncovered. 



The neck (cervix) is the narrow anterior part of the bladder that joins 

 the urethra : in the state of contraction it is the lowest part of the viscus, 

 but in distension it is above the level of the fundus. It is surrounded by 

 the prostate gland. 



