That piriformis sure can be a real pain in the…
I love tackling the “buzz” word muscles and topics. Piriformis fits into a category of muscle names that I hear so commonly. Other muscles and topics include psoas, QL (quadratus lumborum), sciatica, and others. Piriformis is an important muscle, no doubt, and of course it is a “buzz” word for a reason. I think the most common reason people know about the piriformis muscle is because of its relationship to the sciatic nerve. It lies across and just superficial to this major nerve that feeds the back of each leg.
Where is the piriformis?
The piriformis is one of six muscles in a group known as the deep 6 lateral or external rotators of the hip joint. Very few people seem to know the names of the other muscles in this group. They are: gemellus superior, gemellus inferior, obturator internus, obturator externus, and quadratus femoris. These six along with the gluteus minimus are the deepest layer of tissues in the buttocks. In my last newsletter I posted a video on lotus prep, which stretches these very tissues, piriformis included. The piriformis attaches on the inside (anterior) surface of the sacrum. You can see it labeled below. It then heads outward and forward (laterally and anteriorly) to its other attachment on the top of the greater trochanter.
Piriformis and the SI joint
Piriformis pain is often associated with the sciatic nerve. However, there is another very important and interesting relationship at work. The relationship I’m referring to is this muscle’s relationship to movement or stability 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 of the piriformis attachment on the inside of the sacrum and its direction 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.
It’s for this reason that if one is experiencing SI joint pain, the tensional relationship between the psoas and the piriformis should be assessed. When I say assessed, I mean you could either create situations that test the flexibility/tension of these tissues, or better still, directly palpate (touch) these muscles. This unfortunately 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.
Piriformis syndrome and sciatica: Where does the buzz comes from?
“Piriformis syndrome” is the real reason why this muscle can be a real pain in the… In this syndrome, the piriformis muscle (for a variety of reasons) is so tight that it places pressure on the sciatic nerve, creating pain, tingling, or numbness in the buttocks and down the back of the leg. These are of course the same symptoms found in “sciatica”. However, in the case of sciatica, these symptoms are actually coming from the spine. It is therefore helpful if one can differentiate between the two. As it turns out there is a very simple way of doing this. The accuracy of the test is good, but please don’t confuse this simple test with being a doctor and producing a diagnosis. Use the results as information and continue to proceed with caution if you or a student wants to try and differentiate between the two.
The simple test to differentiate between sciatica coming from the spine, possibly disc compression, and the piriformis compressing the sciatic nerve, is this: Lie on your back. Lift the leg of the affected side. If the leg is able to lift higher than a foot off the ground there is a good chance that it is piriformis that is tight. If you were to lift your leg and within six inches have shooting pain down the back of the leg, it’s more likely to be coming from the nerve being compressed closer to the spine. I cover more on the potential reasons that piriformis could contribute to pain in the body on pages 117-118 of my book (1st ed.) Functional Anatomy of Yoga.
Why the difference?
Your nerves stretch along with your myofascia (muscles and connective tissues). The positioning and nature of the piriformis will allow the sciatic nerve to stretch more or less uninhibited. If the compression is from a disc or even vertebrae at the spine, it’s generally less forgiving. As the nerve is stretched while being compressed by either of these structures, it will send a shooting sensation down the back of the leg. Again, this is for information gathering rather than making a positive diagnosis of your own or someone else’s pain.
There’s another sneaky problem that can mirror a similar pain pattern. Trigger points in the gluteus minimus muscle can create a similar kind of pain pattern in the buttocks and down the leg. In this case, the pain is often described differently. The person will also have pain in the buttocks and down the back of the leg but it will generally be more like a dull achiness, or a weak feeling in the leg. Occasionally though it will be described as a shooting type of pain. Sitting for long periods of time also often aggravates trigger points in this muscle. I’ve even had a few students who complain about a hamstring tear and sit bone pain who found upon further inspection that it was a trigger point in the gluteus minimus muscle creating the pain. Even the piriformis itself can generate trigger points that can be misdiagnosed. See the image below.