How the bladder functionsThe bladder is a muscle. You may think of it as a small balloon. The bladder holds the urine produced by the kidneys. It expands to fill, and contracts to empty. However, the bladder must work together with the sphincter muscle, which helps to hold the urine in the bladder.

When urine is stored, the bladder is relaxed and the sphincter contracts to keep the urine inside the bladder. The system is controlled through the spinal cord and brain. When the bladder is full, the brain receives a message of discomfort.The brain, in turn, signals the bladder when there is an appropriate time to urinate, or void.

Voiding occurs by relaxing the sphincter muscle and contracting the bladder muscle. The urethra, a tube to the outside of the body, conducts the urine from the bladder.

When any part of the system such as the bladder, spinal cord, or brain is not working properly, there may be leakage of urine.

Simply defined, incontinence means the involuntary release of urine at the wrong time and/or place.