external urinary sphincter
Quick Summary
The external urinary sphincter is a ring of striated muscle that surrounds the opening of the urethra and is under voluntary control. This sphincter plays a crucial role in the process of urination, allowing individuals to consciously control the release of urine from the bladder.12
The bladder itself is a hollow, muscular organ that stores urine. Its wall contains a powerful detrusor muscle responsible for emptying the bladder. At the base of the bladder, the internal opening of the urethra is surrounded by the internal sphincter, which is involuntary. The external sphincter, located below the internal sphincter, is composed of striated muscle and provides voluntary control over urination.2
The coordinated action of these sphincters, along with the detrusor muscle and nervous system signals, ensures continence and allows for controlled voiding of urine.234
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