The total length of the ureter is in the range of 25-35cm, with the upper section being about 10cm. The ureters are a pair of muscular luminal organs whose physiologic function is to transport urine produced by the kidneys to the bladder and expel it. At the anatomical level, the ureter is divided into abdominal, pelvic and intramural segments, which are clinically referred to as the upper, middle and lower segments. The upper segment is the segment from the pyeloureteral junction to the upper edge of the sacroiliac joint, while the segment between the upper and lower edges of the sacroiliac joint is called the middle segment, and the lower segment is the ureter that runs from the lower edge of the sacroiliac joint to the bladder. There are three physiologic strictures in the anatomy of the ureter. The first narrowing is the junction of the renal pelvis and the ureter, the second narrowing is the portion of the ureter that crosses the iliac vessels, and the third narrowing is the medial segment. These three strictures are areas where stones tend to lodge and become embedded.