Which type of muscle controls the actions of the internal urethral sphincter?

The internal urethral sphincter is primarily controlled by involuntary muscle, specifically composed of smooth muscle fibers. This type of muscle is regulated by the autonomic nervous system and is not under conscious control, which is essential for maintaining the proper involuntary functions of bodily processes such as urination.

Involuntary muscle, which includes smooth muscle, plays a vital role in controlling the internal urethral sphincter, allowing it to contract and relax without conscious thought. This control is crucial for maintaining continence and coordinating micturition.

Skeletal muscle, which is under voluntary control, does not play a role in this sphincter's function. Cardiac muscle, while also involuntary, is specifically associated with heart function and has no involvement in the urethra. Striated muscle generally refers to both skeletal and cardiac muscle, but since the internal urethral sphincter does not involve striated muscle, this would also be an incorrect characterization.

Thus, recognizing that the internal urethral sphincter is managed by involuntary smooth muscle highlights the importance of autonomic control in the regulation of internal bodily mechanisms.