Anatomy for Yoga: The Piriformis Muscle

The Piriformis Muscle

OVERVIEW

Location:
Posterior aspect of pelvis, deep to Gluteus Maximus and just inferior to Gluteus Medius

Word Origin:
Piriformis is Latin, meaning “pear-shaped”

Attachments:
Axial (origin): anterolateral sacrum
Appendicular (insertion): greater trochanter of the femur

Actions:
With thigh flexed less than 60 degrees...
* Lateral (external) rotation of the thigh at the hip joint 

With thigh flexed more than 60 degrees...
* Medial (internal) rotation of the thigh at the hip joint
* Horizontal abduction of the thigh at the hip joint

NOTES:

• The position of the thigh will determine whether the piriformis is a lateral or medial rotator of the thigh at the hip joint, as well as what actions must be created to stretch it (the thigh must be flexed to at least 60 degrees for the piriformis to become a medial rotator of the thigh) 
• If someone has a tight piriformis, when they sit cross-legged their knees will be really high (which is a reflection of the femurs not being able to laterally (externally) rotate to drop the knees toward the floor); they should avoid pigeon pose and anything lotus-related until they get a little more flexibility in the hips, as these postures can compress the medial meniscus if the femur doesn't laterally rotate enough (there would be a pain on the inner knee)
• The following yoga postures can safely stretch the piriformis (in all of them the thigh is flexed more than 60 degrees):  

1. Thread the Needle pose
2. Flying Crow prep pose
3. Cross-Legged pose (folding forward) 
4. Lizard pose (with the knee dropping out to the side) 

• The piriformis can protectively tighten when the sacroiliac joint is sprained or in distress 
• Piriformis syndrome is when a tight or inflamed piriformis muscle compresses the sciatic nerve (which exits nearby) and can mimic sciatica (traveling pain down the lateral buttocks and posterior thigh/leg) 

I'll be posting pics of the above postures on the Zenyasa and ASFYT facebook pages soon ;-)