Which type of muscle makes up the external urethral sphincter?

The external urethral sphincter is composed of skeletal muscle. This muscle type is under voluntary control, allowing individuals to consciously tighten or relax the sphincter to manage the flow of urine. This voluntary control is crucial for functions such as continence, enabling a person to maintain urinary retention and decide when to void.

Skeletal muscle fibers are striated and enable rapid and forceful contractions, which is essential for the sphincter's function during activities that might increase abdominal pressure or when a person needs to hold urine. The presence of skeletal muscle in the external urethral sphincter differentiates it from the internal urethral sphincter, which consists of smooth muscle that operates involuntarily.

Both smooth muscle and cardiac muscle serve different functions in the body but do not contribute to the external urethral sphincter's structure or function. Connective tissue provides supporting structures and does not have the active contraction capability necessary for manipulation of urine flow.