THORAX ABDOMEN AND PELVIS

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: -Controlling the outflow of urine are two valves, or sphincters, located in the bladder neck and earliest portion of the urethra. The bladder neck sphincter is under involuntary (autonomic) control while the urethral sphincter has both voluntary and involuntary components.

Detailed explanation-3: -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-4: -The bladder sphincter is made up of two muscles, the internal and external sphincter muscles. The internal sphincter muscle is located at the opening of the bladder to the urethra. It is a smooth, involuntary muscle. Because of its location, it is also primary muscle prohibiting the release of urine.