Sacral Nerves

Abstract

The posterior femoral cutaneous nerve is also referred to as the lesser sciatic nerve. It originates from the S1 to S3 roots. It exits from the pelvis by passing anterior to the piriformis muscle and posteromedial to the sciatic nerve, innervating the perineum and inferior gluteal skin. Its course is then in the muscular groove between the medial and lateral hamstring muscles. It passes distally through the popliteal fossa, innervating the posterior thigh, and extends distally, innervating the posterior calf with the lateral sural and saphenous nerves. The sacral region is difficult to evaluate. In the male, the dorsal nerve of the penis is the terminal branch of the pudendal nerve and serves as the sensory supply for most of the penis. It is also the afferent arc of the bulbocavernosus reflex entering through the S1 through S3 roots. These studies are useful in evaluating patients with abnormalities of sexual, bowel, or bladder function.