Definition:
Urinary Incontinence - the involuntary and unplanned leakage of urine due to loss of bladder control.
Physiologic Anatomy:
The urinary bladder is a smooth muscled organ composed of two parts: (a) the body – the major part of the bladder where the urine collects, and (b) the neck – which is a funnel-shaped extension of the body, passing inferiorly to the urethra.
The smooth muscle of the bladder is known as the detrusor muscle. Its muscle fibers extend in all directions and, when contracted, it can increase the pressure in the bladder to sometimes as high as 40-60 mmHg.
On the posterior wall of the bladder, immediately above the bladder neck, two ureters enter the bladder. Where each ureter enters the bladder, it courses obliquely through the detrusor muscle and then pass underneath the bladder mucosa before emptying into the bladder.
Another name for the bladder neck muscle is internal sphincter. Its natural tone keeps the bladder neck and posterior urethra empty of urine and therefore prevents emptying of the bladder until the pressure in the body of the bladder rises above a critical threshold.
Beyond the posterior urethra, the urethra passes through the urogenital diaphragm, which contains a layer of muscle called the external sphincter of the bladder. This muscle is a voluntary skeletal muscle, in contrast to the muscle of the bladder body and bladder neck, which is entirely smooth muscle. This external muscle is under voluntary control of the nervous system and can be used to prevent urination, even when the involuntary controls are attempting to empty the bladder.
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Tags: bed wetting, Bladder Weakness, Types of Incontinence, uncontrolled urination, Urinary Incontinence, urinary system
