Muscle of Gluteal Region: Abductor and Rotator of Thigh

The pear-shaped piriformis (Latin pirum, a pear) is located partly on the posterior wall of the lesser pelvis, and partly posterior to the hip joint. The piriformis leaves the pelvis through the greater sciatic foramen, almost filling it, to reach its attachment to the superior border of the greater trochanter.

Because of its key position in the buttocks, the piriformis is the landmark of the gluteal region. The piriformis provides the key to understanding relationships in the gluteal region because it determines the names of the blood vessels and nerves:

• The superior gluteal vessels and nerve emerge superior to it.

• The inferior gluteal vessels and nerve emerge inferior to it.

Muscle: Piriformis

Proximal Attachment: Anterior surface of sacrum; sacrotuberous ligament

Distal Attachment: Superior border of greater trochanter of femur

Innervation: Branches of anterior rami of S₁, S₂

Main Action(s): Laterally rotates extended thigh and abducts flexed thigh; steadies femoral head in acetabulum