By Christy Cael
[Functional Anatomy]

Piriformis is one of six deep hip external rotators. This group of muscles is located deep to the gluteus maximus and gluteus medius in the posterior pelvis and functions similarly to the rotator cuff in the shoulder.

Coordinated activation of these muscles helps stabilize the hip joint and position the femoral head during movements of the lower extremity. The other deep external rotators include superior and inferior gemellus, obturator internus and externus, and the quadratus femoris.

Piriformis is the most superior of the deep six external rotators. Its fibers extend laterally between the anterior surface of the sacrum and the greater trochanter of the femur. It functions similarly to the supraspinatus by levering the head of the femur into optimal position while the larger pelvic muscles (gluteals, hip flexors, etc.) perform their actions.

Piriformis is unique in that it is strongly associated with the sciatic nerve. This large nerve extends from the sacral plexus through the greater sciatic notch of the pelvis and under or through the piriformis muscle before extending distally into the lower extremity. Tightness in piriformis may compress the sciatic nerve, causing radiating pain, weakness, and altered sensation in the lower extremity. This mimics the symptoms of nerve root compression associated with a protruding intervertebral disc or degenerative changes in the spine.

Piriformis tightness results from either excessive muscle contraction or excessive lengthening, so accurate postural assessment of the lower extremity is essential in planning treatment. In standing, excessive contraction of piriformis results in posterior pelvic tilt and external rotation of the hip. Excessive lengthening is associated with anterior pelvic tilt, hip adduction, and hip medial rotation.

Palpating Piriformis

Positioning: client prone

1. Standing at the client’s side facing the hip, locate the lateral edge of the sacrum with your fingertips.

2. Slide your fingertips laterally and distally toward the greater trochanter. (Caution: the sciatic nerve lies near the muscle belly of piriformis. To avoid compressing it, palpate following the oblique muscle fibers.)

3. Palpate and follow the muscle fibers as they converge and insert on the superior surface of the greater trochanter.

4. Gently resist external rotation of the hip to assure proper location.

  Christy Cael is a licensed massage therapist, certified athletic trainer, and certified strength and conditioning specialist. Her private practice focuses on injury treatment, biomechanical analysis, craniosacral therapy, and massage for clients with neurological issues. She is the author of Functional Anatomy: Kinesiology and Palpation for Manual Therapists (Lippincott Williams & Wilkins, 2009). Contact her at functionalbook@hotmail.com.