ANATOMY

Detailed explanation-1: -Two muscles as urethral sphincters are used to control the exit of urine in the urinary bladder through the urethra. The two muscles are the internal and EUS.

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: -The internal urethral sphincter is located at the junction of the urethra and the urinary bladder. It is made of smooth muscle, and is under autonomic or involuntary control. The more inferiorly located external urethral sphincter surrounds the membranous or intermediate part of the urethra.

Detailed explanation-4: -A ring-shaped muscle that relaxes or tightens to open or close a passage or opening in the body. Examples are the anal sphincter (around the opening of the anus) and the pyloric sphincter (at the lower opening of the stomach).

Detailed explanation-5: -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.