Muscle
Piriformis
Key landmark of the gluteal region
High-yield
Divides the greater sciatic foramen; sciatic nerve usually exits below it. Lateral rotator of the extended hip.
Overview
A pear-shaped muscle exiting the greater sciatic foramen that laterally rotates the extended thigh and is the central landmark of the gluteal region.
Reference facts
- Origin
- Anterior (pelvic) surface of the sacrum
- Insertion
- Superior border of the greater trochanter of the femur
- Action
- Laterally rotates the extended thigh; abducts the flexed thigh; stabilises the hip
- Innervation
- Nerve to piriformis (anterior rami S1, S2)
- Blood supply
- Superior and inferior gluteal arteries
Frequently asked questions
What does the piriformis do?
The piriformis laterally rotates the extended thigh; abducts the flexed thigh; stabilises the hip.
What nerve innervates the piriformis?
The piriformis is innervated by the nerve to piriformis (anterior rami S1, S2).
Where does the piriformis attach?
The piriformis originates from the anterior (pelvic) surface of the sacrum and inserts on the superior border of the greater trochanter of the femur.
What is the blood supply of the piriformis?
The piriformis is supplied by the superior and inferior gluteal arteries.