Nerve supply to perineum

The nerve supply to the perineum originates from three main sources:

1. The Genito-femoral Nerve (L1,L2).

2. The pudendal nerve arises from the anterior rami of the second to fourth sacral roots. These form a trunk before leaving the pelvis via the greater sciatic foramen. It passes immediately behind the ischial spine and swings forward to enter the perineum via the lesser sciatic foramen. The nerve passes through the ischiorectal fossa where it gives off its terminal branches. The inferior rectal nerve innervates the external anal sphincter and the perianal skin. The perineal nerve innervates the sphincter urethrae and other muscles of the anterior compartment via a deep branch, and the skin of the perineum poterior to the clitoris via its superficial branch. The dorsal nerve of the clitoris supplies the skin surrounding this structure.

3. The perineal branch of the posterior femoral nerve.