

THE URINARY BLADDER 



distinct as far as the fundus of the bladder. On rare occasions they open 

 separately into the bladder cavity. 



Structure (Fig. 1134). The ureter is composed of three coats: fibrous, muscular, and mucous 

 coats. 



The fibrous coat (tunica adventitia) is continuous at one end with the fibrous tunic of the kidney 

 on the floor of the sinus; while at the other it is lost in the fibrous structure of the bladder. 



In the renal pelvis the muscular coat (tunica muscularis) consists of two layers, longitudinal 

 and circular: the longitudinal fibers become lost upon the sides of the papillae at the extremities 

 of the calyces; the circular fibers may be traced surrounding the medullary substance in the 

 same situation. In the ureter proper the muscular fibers are very distinct, and are arranged 

 in three layers: an external longitudinal, a middle circular, and an internal, less distinct than 

 the other two, but having a general longitudinal direction. According to Kolliker this internal 

 layer is found only in the neighborhood of the bladder. 



The mucous coat (tunica mucosa) is smooth, and presents a few longitudinal folds which 

 become effaced by distension. It is continuous with the mucous membrane of the bladder 

 below, while it is prolonged over the papillae of the kidney above. Its epithelium is of a tran- 

 sitional character, and resembles that found in the bladder (see Fig. 1141). It consists of sev- 

 eral layers of cells, of which the innermost that is to say, the cells in contact with the urine- 

 are somewhat flattened, with concavities on their deep surfaces into which the rounded ends 

 of the cells of the second layer fit. These, the intermediate cells, more or less resemble columnar 

 epithelium, and are pear-shaped, with rounded internal extremities which fit into the concavities 

 of the cells of the first layer, and narrow external extremities which are wedged in between the 

 cells of the third layer. The external or third layer consists of conical or oval cells varying in 

 number in different parts, and presenting processes which extend down into the basement 

 membrane. Beneath the epithelium, and separating it from the muscular coats, is a dense layer 

 of fibrous tissue containing many elastic fibers. 



Vessels and Nerves. The arteries supplying the ureter are branches from the renal, internal 

 spermatic, hypogastric, and inferior vesical. 



The nerves are derived from the inferior mesenteric, spermatic, and pelvic plexuses. 



Variations. The upper portion of the ureter is sometimes double; more rarely it is double the 

 greater part of its extent, or even completely so. In such cases there are two openings into the 

 bladder. Asymmetry in these variations is common. 



The Urinary Bladder (Vesica Urinaria; Bladder) (Fig. 1135). 



The urinary bladder is a musculomembranous sac which acts as a reservoir 

 for the urine; and as its size, position, and relations vary according to the amount 

 of fluid it contains, it is necessary to study it as it appears (a) when empty, and (6) 

 when distended. In both conditions the position of the bladder varies with the 

 condition of the rectum, being pushed upward and forward when the rectum is 

 distended. 



The Empty Bladder. When hardened in situ, the empty bladder has the 

 form of a flattened tetrahedron, with its vertex tilted forward. It presents a fundus, 

 a vertex, a superior and an inferior surface. The fundus (Fig. 1152) is triangular 

 in shape, and is directed downward and backward toward the rectum, from which 

 it is separated by the rectovesical fascia, the vesiculse seminales, and the terminal 

 portions of the ductus deferentes. The vertex is directed forward toward the upper 

 part of the symphysis pubis, and from it the middle umbilical ligament is continued 

 upward on the back of the anterior abdominal wall to the umbilicus. The peri- 

 toneum is carried by it from the vertex of the bladder on to the abdominal wall 

 to form the middle umbilical fold. The superior surface is triangular, bounded 

 on either side by a lateral border which separates it from the inferior surface, and 

 behind by a posterior border, represented by a line joining the two ureters, which 

 intervenes between it and the fundus. The lateral borders extend from the ureters 

 to the vertex, and from them the peritoneum is carried to the walls of the pelvis. 

 On either side of the bladder the peritoneum shows a depression, named the para- 

 vesical fossa (Fig. 1037) . The superior surface is directed upward, is covered by peri- 

 toneum, and is in relation with the sigmoid colon and some of the coils of the small 

 intestine. When the bladder is empty and firmly contracted, this surface is convex 





