**Core Concept:** The pudendal nerve is a peripheral nerve that arises from the sacral plexus, specifically from S2, S3, and S4 spinal nerves. It supplies sensory and motor innervation to the perineum, external genitalia, and anal sphincters.

**Why the Correct Answer is Right:** The correct answer is derived from understanding the origin and distribution of the pudendal nerve. The pudendal nerve is formed from contributions from S2, S3, and S4 spinal nerves, which are part of the sacral plexus. The pudendal nerve provides sensory innervation to the perineum, external genitalia, and motor innervation to the external anal sphincter.

**Why Each Wrong Option is Incorrect:**

A. The pudendal nerve does not arise from L4, L5, or S1 spinal nerves. It is solely formed from contributions of S2, S3, and S4 spinal nerves.

B. Although the pudendal nerve supplies the external anal sphincter, it arises from the sacral plexus rather than the lumbar plexus.

C. The pudendal nerve does not exclusively innervate the pubococcygeus muscle, as it also innervates other structures like the perineum and external anal sphincter.

D. The L5 spinal nerve is part of the lumbar plexus, not the sacral plexus, where the pudendal nerve originates.

**Clinical Pearl:** The pudendal nerve serves as a key landmark in identifying the correct sacral segment during spinal surgery, as it innervates sensitive structures in the perineum and external anal sphincter, making its preservation essential during sacral interventions.