Anterior root of posterior femoral cutaneous nerve

At a glance

English

Anterior root of posterior femoral cutaneous nerve

Latin (TA2)

Radix anterior nervi cutanei femoris posterioris

System

Nerve

Region

Lower limb

Side

Paired, left and right

About the anterior root of posterior femoral cutaneous nerve

The posterior femoral cutaneous nerve is a sensory branch of the sacral plexus, formed inside the pelvis from fibres of the first three sacral nerves. It has two roots. The anterior root is made of fibres from the anterior (ventral) divisions of the anterior rami of the second and third sacral nerves. The posterior root brings fibres from the posterior (dorsal) divisions of the first and second sacral nerves.

The sacral plexus lies on the front of piriformis, behind the parietal pelvic fascia. The two roots join on the front of this muscle, and the combined nerve leaves the pelvis through the greater sciatic foramen below piriformis, alongside the inferior gluteal nerve and vessels and close to the sciatic nerve.

The mixed origin of the nerve fits the area it serves, which includes the back of the thigh and the lower buttock as well as the perineum. The fibres of the anterior root are often described as passing into the perineal branches of the nerve, which supply the skin of the upper medial thigh and the perineum. Because this root is drawn from the second and third sacral nerves, lesions of these roots, as in compression of the cauda equina, can reduce sensation in the skin of the perineum and back of the thigh, part of the so-called saddle area.

Course and supply

Arises from

Anterior divisions of the anterior rami of the second and third sacral nerves, in the sacral plexus.

Ends in

Joins the posterior root on the front of piriformis to form the posterior femoral cutaneous nerve.

Supplies

Carries sensory fibres from S2 and S3 into the posterior femoral cutaneous nerve.