The ureters are the two tubes which convey the urine from the kidneys to the urinary bladder.
Each commences within the sinus of the corresponding kidney as a number of short cup-shaped tubes, termed calyces, which encircle the renal papillæ. Since a single calyx may enclose more than one papilla the calyces are generally fewer in number than the pyramids—the former varying from seven to thirteen, the latter from eight to eighteen.
The calyces join to form two or three short tubes, and these unite to form a funnel-shaped dilatation, wide above and narrow below, named the renal pelvis, which is situated partly inside and partly outside the renal sinus. It is usually placed on a level with the spinous process of the first lumbar vertebra.
The Ureter Proper measures from 25 to 30 cm. in length, and is a thick-walled narrow cylindrical tube which is directly continuous near the lower end of the kidney with the tapering extremity of the renal pelvis. It runs downward and medialward in front of the Psoas major and, entering the pelvic cavity, finally opens into the fundus of the bladder.