What role does the pudendal nerve play in urinary function?

The pudendal nerve plays a significant role in controlling the external urethral sphincter, which is crucial for voluntary control of urination. By preventing external sphincter relaxation, the pudendal nerve helps maintain continence. When the bladder fills and stretch receptors are activated, the nervous system signals the bladder to contract; however, the ability to postpone urination is facilitated by this nerve's inhibition of sphincter relaxation, allowing conscious control over when to void.

In contrast, the roles described in the other options involve different nerves or mechanisms entirely. For example, bladder stretching and contracting forces are primarily regulated by the autonomic nervous system, particularly through the pelvic splanchnic nerves and other pathways. The detrusor muscle, responsible for bladder contractions, is influenced by parasympathetic activation, which is not directly mediated by the pudendal nerve.