Nerve · Pelvis

Sacral plexus

Plexus sacralis

The sacral plexus is the nerve network of the buttock and the whole leg below the knee, lying on the back wall of the pelvis in front of piriformis. It is fed by the lower lumbar and upper sacral nerves and gives rise to the largest nerve in the body, the sciatic, along with the gluteal nerves that power the hip. Nearly all of its output leaves the pelvis through the greater sciatic foramen, passing either above or below piriformis — a crowded gateway that makes the buttock an anatomically busy and clinically important place.