Perforating cutaneous nerve

The perforating cutaneous nerve is a cutaneous nerve that arises from the S2 and S3 nerve roots of the sacral plexus. The nerve exits the pelvis by piercing the sacrotuberous ligament to eventually supply the lower medial part of the buttock.

Gross anatomy

Origin

The perforating cutaneous nerve arises from the posterior aspect of the anterior rami of S2 and S3 nerve roots.

Course

Unlike the majority of the nerves of the sacral plexus that exit the pelvic cavity through the greater sciatic foramen, the perforating cutaneous nerve pierces the sacrotuberous ligament and is briefly at the posterior edge of the ischioanal fossa. The nerve then passes over the lower border of the gluteus maximus muscle and continues to supply the skin over inferior aspects of the buttocks (also described as the area at which the two buttocks are losing contact).

Relations

The perforating cutaneous nerve briefly runs within the sacrotuberous ligament; a flat, triangular, broad based ligament. The ligament also houses the coccygeal branch of the inferior gluteal artery.

The sacrotuberous ligament along with the gluteus maximus muscle forms the posterior boundary of the ischioanal (ischiorectal) fossa a fat filled fossa of the perineum. The ischioanal fossa contains the pudenal canal which in turn contains the pudendal nerve and internal pudendal vessels.

Variant anatomy

The perforating cutaneous nerve may be absent in which its place may be taken by a branch from the posterior cutaneous nerve of the thigh, a branch from the pudendal nerve or by a small nerve arising from the third and fourth or fourth and fifth sacral nerves.