Perineal Nerve

Origin

The perineal nerve is one of three terminal branches of the pudendal nerve inside the perineum.

Course

The pudendal nerve travels along the lateral wall of the ischioanal fossa in the pudendal canal to reach the anal triangular region of the perineum. Inside the perineum (in the anal triangle), the pudendal nerve gives off a perineal nerve. The perineal nerve passes into the urogenital triangle and gives rise to motor and sensory cutaneous branches.

Branches

The perineal nerve gives muscular branches to muscles in the superficial and deep perineal pouches, sensory branches for skin of urogenital triangle, including the posterior scrotal nerve (males) or posterior labial nerve (females). In rare cases, the perineal nerve innervates the external anal sphincter. It first enters a plexus inside the ischiorectal fossa (along with the inferior rectal nerve) (Antolak et al., 2002).

Supplied Structures

The perineal nerve supplies motor innervation to skeletal muscles in the superficial and deep perineal pouches (ischiocavernosus, bulbospongiosus, superficial transverse perineal muscle, deep transverse perineal muscle, external urethral sphincter, and compressor urethrae). Often the perineal nerve innervates the external anal sphincter.

The perineal nerve supplies sensory innervation to the skin of urogenital triangle. The largest sensory branch is the posterior scrotal (males) or posterior labial (females).

References

Antolak, S. J., Hough, D. M., Pawlina, W. and Spinner, R. J. (2002) 'Anatomical basis of chronic pelvic pain syndrome: the ischial spine and pudendal nerve entrapment', Med Hypotheses, 59(3), pp. 349-53.