SECRETION. 433 



and allows of the passage of the vessels, nerves, and ureter to and 

 from the substance of the kidney. Just within the hilus is a dilated 

 fossa known as the sinus^ which contains the renal artery, the vein, 

 and the pelvis of the kidney. The relation of the structures passing 

 in and out of the hilus from before backward are: vein in front, 

 artery in the middle, and the duct, or ureter, behind and toward the 

 lower part. By keeping in mind, these relations one will be able to 

 distinguish the right from the left kidney after their removal from 

 the body. 



In the funnel-shaped cavity of the renal pelvis is the ureter. 

 From the kidney it passes over the psoas muscle, converging toward 

 that of the opposite side to cross the external iliac artery and vein. 

 It opens obliquely into the base of the urinary bladder. In females 

 the ureter embraces the neck of the uterus. The ureters have an 

 average length of eighteen inches and a lumen which averages that of 

 a goose-quill. Just before piercing the bladder-wall the lumen of 

 the ureter becomes appreciably smaller. 



The urinary bladder, situated between the symphysis pubis and 

 the rectum in man, between the symphysis and the uterus in woman, 

 is held in position by the urachus and lateral ligaments. Its base 

 rests upon the perineum and anterior wall of the rectum in man, 

 upon the anterior wall of the vagina in woman. From the base of 

 the bladder the urethra takes its origin. 



The opening for the latter bears such a relation to the entrance 

 into the bladder of the two ureters that there is formed the vesical 

 triangle. The openings for the ureters are about sixty millimeters 

 apart. 



The capacity of the bladder varies with its extensibility, so that 

 it is possible for the viscus to be so distended that its upper border 

 may reach the umbilicus or even the epigastric region. Ordinarily 

 the capacity in both sexes is about a pint. 



The bladder receives its blood-supply from the branches of the 

 anterior trunk of the internal iliac. The lymphatic vessels communi- 

 cate with the lumbar ganglia. The nerves are derived from the sym- 

 pathetic, sacral, and probably some fibers from the pneumogastric 

 also. 



General Structure of the Kidney, Beneath the perirenal fat lies 

 the proper tunic, or covering, of the kidney, commonly called the 

 capsule. In health it is a smooth, thin, but tough, fibrous covering, 

 closely adherent to the organ, but from which it can be readily 

 stripped. By reason of this separation, however, fine connective- 



