The Piriformis Muscle

January 16, 2014
The Piriformis Muscle

What does piriformis mean?

The Latin name for the piriformis muscle is musculus piriformis. Piriformis translates as “pear shaped” muscle. The word piriformis comes from the Latin words pirum meaning “pear” and forma meaning “form or shape.”

Where does the piriformis muscle attach?

  • The muscle attaches to the anterior sacrum which is on the inside of the pelvic bowl.
  • The other end of the muscle attaches to the very top of the femur, which is called the greater trochanter.

The Piriformis Muscle

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What are the actions of the piriformis muscle?

This muscle externally rotates the femur and assists in abduction of the femur at the hip joint. Although we don’t abduct our leg often in a way that activates this muscle, one example of this action occurs in single-legged balancing postures when the piriformis helps stabilize the pelvis.

Piriformis and the SI joint

In addition to doing abduction of the thigh at the hip, piriformis is also an important muscle for maintaining stability and balance in our body.  Specifically, it helps allow for or restrict movement at the SI (sacro-iliac) joint. You can read my post on nutation counter-nutation if you’re curious about the movements of the SI joint.

Because the piriformis attaches on the inside of the sacrum and runs forward to attach onto the big bump at the top of the femur (greater trochanter), it creates a tensional force on the sacrum at the sacroiliac joint. This force is the opposite of the force generated by the psoas muscle. The two, therefore, create a certain balance of forces at the SI joint. You can find more on the psoas on the psoas resource page.

So, if you’re experiencing SI joint pain, one thing to assess is the tensional relationship between the psoas and the piriformis. When I say assess, I mean you could either create situations that test the flexibility/tension of these tissues, or better still, directly palpate (touch) these muscles. This of course assumes you have the skill to do that. You could also experiment with stretching both the psoas and the piriformis. Stretching the psoas requires extending the hip joint. A lunge can do the trick if the other hip flexors of the same side aren’t overly tight as well.

Postures where this muscle contracts

piriformis muscle in utthita hasta padangusthasana

The piriformis muscle contracts on the right side in standing leg raise to stabilize the pelvis relative to the femur.

Postures where this muscle is lengthened

piriformis muscle in pigeon pose

Pigeon is a classic example. The closer the front leg is to parallel with the front line of the mat, the more pressure goes into the piriformis muscle.

Common problems and additional information

Among muscles, the piriformis muscle is especially popular. I wrote an article on it titled: Sciatica, Piriformis Syndrome, and Yoga. It’s also mentioned in two other articles: one on sit bone pain and the other discussing the gluteal and psoas relationship. Let’s give it the attention it deserves right here though. The muscle is a lightning rod. Anytime anyone has pain in their buttocks it must be the piriformis, right? It could be, but it’s not necessarily the source of the pain. There are plenty of other causes of pain in the buttocks as outlined in the articles I linked to above.

Piriformis syndrome

Piriformis syndrome is probably one of the most common reasons that everyone has heard of the piriformis muscle. It’s a syndrome that can be confused with sciatica. You can read more in my post on sciatica, piriformis syndrome, and yoga. While a tight piriformis compressing the sciatic nerve is part of the description of this syndrome, it’s actually more specific than that. In fact, one of the more common causes is repetitive contraction of the muscle. Sorry runners, you’re more likely to end up with piriformis syndrome. If you have a tight piriformis and want to stretch it out, great, just don’t overdo it. While stretching can help, too much stretching can inflame it more! Although there are multiple postures that stretch this muscle, I usually recommend pigeon and its variations for this purpose.

Trigger points

Piriformis Trigger Points