MICROANATOMY

Detailed explanation-1: -The internal urethral sphincter regulates involuntary control of urine flow from the bladder to the urethra, and the external urethral sphincter provides voluntary control of urine flow from the bladder to the urethra.

Detailed explanation-2: -Your urinary sphincter is a muscle that controls the flow of urine (pee) out of your bladder (see Figure 1). When your urinary sphincter is contracted (closed), it blocks the opening of your bladder so urine doesn’t leak out.

Detailed explanation-3: -The Two Urethral Sphincters Maintain Urinary Continence The internal sphincter is involuntary. It surrounds the opening of the bladder to the urethra and relaxes to allow urine to pass. The external sphincter is voluntary. It surrounds the urethra outside the bladder and must be relaxed for urination to occur.