Ureter

There are two uterine tubes that carry urine from the kidneys to the bladder. Each ureter is about ten to twelve inches long. Urine flows down partly by gravity, but mainly by waves of contractions which pass several times per minute through the muscle layers of the urethral walls. Each ureter enters the bladder through a tunnel in the bladder wall, which is angled to prevent the urine from running back into the ureter when the bladder contracts.