Piriformis
Piriformis
Pronunciation: peer-ih-FOR-mis
For beginners
A small, deep muscle under your glutes that rotates your thigh outward — think of turning your toes out while standing.
Show the advanced explanation
The sciatic nerve passes very close to (and in some people through) the piriformis; irritation here is discussed as one possible contributor to sciatica-like symptoms, though true nerve root causes are far more common and must be distinguished by a professional.
Structure & function
- Location
- A small, deep muscle running from the inner surface of the sacrum to the top of the thigh bone, deep beneath the gluteus maximus.
- Origin
- Anterior (front) surface of the sacrum.
- Insertion
- Greater trochanter of the femur.
- Main action(s)
- Externally (laterally) rotates the thigh at the hip when the hip is extended; assists hip abduction when the hip is flexed to 90°.
- Joint(s) crossed
- Hip joint
- Movement plane
- transverse
- Innervation
- Nerve to piriformis (branches of S1–S2)
- In daily movement
- Turning the foot/leg outward, such as pivoting to change direction while walking.
- In exercise
- A stabilizer in single-leg standing and rotational movements; often targeted in hip-mobility and glute-activation warm-ups.
- Commonly confused with
- Buttock or posterior-hip pain is often assumed to be 'piriformis syndrome' by default, when low-back nerve involvement is a more common cause and needs proper assessment.
- Common misconceptions
- Stretching alone does not resolve all deep-glute pain — the underlying cause needs identifying, which is outside a trainer's scope.
Exercises that use this muscle
As a primary mover
⚠ Safety note
Pain radiating down the leg, numbness, or tingling should be referred to a healthcare professional rather than treated with stretching alone.
Sources
“The piriformis laterally rotates the extended thigh and abducts the flexed thigh at the hip joint.”
Anatomy and Physiology 2e — OpenStax, Rice University · Ch. 11.6 Appendicular Muscles of the Pelvic Girdle and Lower Limbs
Peer-reviewed textbook · License: CC BY-NC-SA 4.0 · Last checked 2026-07-19
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