The pelvic cavity is a body cavity that is bounded by the bones of the pelvis and which primarily contains reproductive organs, the urinary bladder, and the rectum. The pelvis is a marvel of physiology and is deceptively complex. It contains the lower urinary tract, reproductive system, lower digestive tract, major arteries and veins, muscle systems, nerve systems and bone systems. They all have to work together in a little crowded "house". It can be affected by many different diseases and by many drugs in many different ways. One part may impact upon another, for example constipation may overload the rectum and compress the urinary bladder, or childbirth might damage the pudendal nerves and later lead to anal weakness.