Origin Anterior surface of lateral process of sacrum and gluteal surface of ilium at the margin of the greater sciatic notch Insertion Superior border of greater trochanter Action Lateral rotator of the hip joint; also helps abduct the hip if it is flexed Innervation Piriformis nerve (L5, S1, S2) (L5, S1, S2) Arterial Supply Superior and inferior gluteal and internal pudendal arteries