The urinary bladder, colloquially simply called the “bladder”, collects and stores the urine constantly produced by the kidneys. The urine is then transported from the kidneys via the ureters into the bladder, which it enters in the area of the o-called ostia (ureteral orifices). When the bladder is full, the urge to urinate becomes noticeable and imperative. The urinary bladder enables adults to deliberately release urine via the urethra at certain intervals. The interaction between the bladder and a sophisticated sphincter system is responsible for the controlled release of urine.

Due to its elasticity, the urinary bladder changes its shape from spherical to ultimately pear-shaped as it fills up. The inner lining of the bladder is formed by a special mucous membrane, the so-called urothelium. The bladder is located and well protected in the lesser pelvis (pelvis minor). In women, the bladder is directly adjacent to the uterus at the back of the pelvis; in men, on the rectum. In both sexes, the bladder is located on the pelvic floor and the urethra passes through the pelvic floor. The two sphincter muscles of the bladder are also located in this area.

There is a large number of acquired and congenital diseases of the urinary bladder and the urethra. Women and men are equally affected.