Piriformis
Musculus piriformis
MuscularDeep musclesPelvisLeft and right
View left in 3D View right in 3D
- What it is
- Pear-shaped muscle arising from the front (pelvic) surface of the sacrum; it leaves the pelvis through the greater sciatic foramen and inserts on the upper border of the greater trochanter.
- Function
- Laterally rotates the extended hip, abducts the flexed hip and helps hold the femoral head in the acetabulum.
- Size
- About 12 cm long, 3-4 cm wide at its origin.
- Clinical note
- Landmark of the buttock: vessels and nerves are described as above or below it. The sciatic nerve passes beneath it (or through it in ~10-15 % of people) - the anatomical basis of "piriformis syndrome".