A highly distensible organ for storing URINE. It consists of smooth muscle known as the detrusor muscle and is lined with urine-proof cells known as transitional cell epithelium.

The bladder lies in the anterior half of the PELVIS, bordered in front by the pubis bone and laterally by the side walls of the pelvis. Superiorly the bladder is covered by the peritoneal lining of the abdomen. The bottom or base of the bladder lies against the PROSTATE GLAND in the male and the UTERUS and VAGINA in the female.