Piriformis Muscle

Authors
Affiliations

Nathaniel Yomogida, B.S., SPT

Doctor of Physical Therapy

B.S. in Kinesiology

Chloë Kerstein, B.S., SPT

Doctor of Physical Therapy

B.A. in Neuroscience

Muscle Origin Insertion Innervation Action
Piriformis Anterior Sacrum Apex of the Greater Trochanter Sacral Plexus Direct Br.
S1 - S2		 Hip (at <60° flexion): ER
Hip: Abduction, Extension, Stabilization
Hip (at ≥60° flexion): IR

Origin

Anterior surface of sacrum

Insertion

Apex of the greater trochanter of the femur

Innervation

Direct branches from sacral plexus S1 and S2

Action

According to Gilroy1, the piriformis functions in External rotation, abduction, extension and stabilization of the hip joint.

This is only partly true.

At ≥60° hip flexion, the piriformis produces an internal rotation torque2.

Anatomy

The Sciatic n. runs superficial to all of the deep external rotators except for the piriformis3. The sciatic nerve can either runs deep to the piriformis and can exit inferiorly, through the piriformis muscle belly, or superior to the piriformis. As a result, overactivation of the piriformis can lead to neurogenic pain and symptoms and is termed Piriformis syndrome

Palpation

  1. Place the patient in prone3.
  2. Palpate the: coccyx, PSIS, and greater trochanter3.
  3. The coccyx to the PSIS is the superior and inferior bounds of the piriformis origin and the greater trochanter is the insertion3.
  4. Bisect the coccyx and PSIS and place a finger there3.
  5. Place your fingers along the imaginary line from the bisection to the greater trochanter3.
  6. Work through the superficial gluteus maximus to palpate the slender piriformis muscle belly3.
  7. Strum across the piriformis muscle belly to palpate its location3.
Caution

The sciatic nerve runs through this area, so be mindful of this when palpating.

Active palpation

One can bend the patient’s knee and ask the patient to perform isometric contractions against gentle resistance to better palpate the piriformis3. The gluteus maximus may be recruited during this process, but the piriformis should be more evident3.

Pathologies

Piriformis tendinitis

“Tenderness to deep palpation near the hook of the greater trochanter. Pain reproduced by piriformis stretch”4

Active Release Technique (ART)

Active release technique for piriformis by Dr. Nick Perkins5

  • Patient in contralateral sidelying
  • STM to piriformis
  • move from hip IR/ABD/Ext into hip ER/Adduction/Flexion

References

1.
Gilroy AM, MacPherson BR, Wikenheiser JC, Voll MM, Wesker K, Schünke M, eds. Atlas of Anatomy. 4th ed. Thieme; 2020.
2.
Neumann DA, Kelly ER, Kiefer CL, Martens K, Grosz CM. Kinesiology of the Musculoskeletal System: Foundations for Rehabilitation. 3rd ed. Elsevier; 2017.
3.
Biel A. Trail Guide to the Body: A Hands-on Guide to Locating Muscles, Bones, and More. 6th ed. Books of Discovery; 2019.
4.
Dutton M. Dutton’s Orthopaedic Examination, Evaluation, and Intervention. 5th ed. McGraw Hill Education; 2020.
5.
Perkins N. Stretch Affect Clinical Internship. Published online 10-14-24.

Citation

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