THE URETERS — THE URINARY BLADDER 561 



THE URETERS 



The ureter is the narrow part of the excretory duct of the kidney. Each 

 begins at the renal pelvis and terminates at the bladder. It is about .^ 3 to ^ inch 

 (ca. 6 to 8 mm.) in diameter, and its average length is about 28 inches (ca. 70 cm.). 

 The abdominal part (Pars abdominalis) of each ureter emerges ventrally from the 

 hilus of the kidney, and curves backward and 'medially toward the lateral face of the 

 posterior vena cava (right side) or the aorta (left side). They then pass almost 

 straight backward in the subperitoneal tissue on the surface of the psoas minor, 

 cross the external iliac vessels, and enter the pelvic cavity. The pelvic part (Pars 

 pelvina) passes backward and a little ventrally on the lateral wall of the pelvic 

 cavity, turns medially, and pierces the dorsal wall of the bladder near the neck. 

 In the male the pelvic part enters the genital fold and crosses the ductus deferens. 

 In the female the ureter is situated in most of its course in the dorsal part of the 

 broad ligament of the uterus. 



The wall of the ureter is composed of three coats. The external fibrous coat 

 (Tunica adventitia) contains many elastic fibers. The muscular coat consists of 

 internal and external layers of longitudinal fibers, -with a stratum of circular fibers 

 between them. The mucous membrane is covered with transitional epithelium; 

 glands (Glandulse mucosae ureteris) resembling those of the renal pelvis occur in the 

 first three or four inches of the ureter. 



The blood-supply is derived from the renal and umbilical arteries. The nerves 

 come from the solar and pelvic plexuses; many minute ganglia are present. 



THE URINARY BLADDER 



The xurinary bladder (Vesica urinaria) (Figs. 366, 369, 370) differs in form, size, 

 and position according to the amount of its contents. When empty and contracted, 

 it is a dense, piriform mass, about the size of a fist, and lies on the ventral wall of 

 the pelvic cavity at a variable distance behind the inlet. When moderately filled, 

 it is ovoid in form, and extends a variable distance along the ventral abdominal wall. 

 Its physiological capacity varies greatly, but may be estimated approximately at 

 about three or four quarts. 



The anterior rounded blind end is termed the vertex ;i on its middle is a mass 

 of cicatricial tissue (Centrum verticis), a vestige of the urachus, which in the foetus 

 forms a tubular connection between the bladder and the allantois. The middle 

 part or body (Corpus vesicae) is rounded, and is somewhat flattened dorso-ventrally, 

 except when distended. It presents two surfaces, dorsal and ventral, the former 

 being the more strongly convex, especially in its posterior part in front of the en- 

 trance of the ureters.2 The posterior narrow extremity, the neck (CoUum vesica;), 

 joins the urethra. 



The relations of the bladder vary according to the degree of fulness of the 

 organ, and also differ in important respects in the two sexes. The ventral sttrface 

 (Facies ventralis) lies on the ventral wall of the pelvis, and extends forward on the 

 abdominal wall as the bladder fills. The dorsal surface (Facies dorsalis) in the male 

 is related to the rectum, the genital fold, the terminal parts of the ductus 

 deferentes, the vesiculaj seminales, and the prostate; in the female it is in contact 

 instead with the body of the uterus and the vagina. The vertex of the full bladder 

 has variable relations with coils of the small intestine and small colon, and the pelvic 

 flexure of the large colon. 



Fixation.— Displacement of the bladder is limited chiefly Ijy three peritoneal 



1 This is often termed the fundus by veterinarians, but is not the homologue of the fundus of 

 the human bladder. 



2 This would correspond to the fundus vesicas of man. 



36 



