The Piriformis Muscle And Piriformis Syndrome
Piriformis syndrome is considered a somewhat controversial condition among the medical fraternity. The condition can mimic sciatica with origin from the lumbar discs and is sometimes also referred to as ‘pseudo sciatica’ or wallet sciatica.
The piriformis muscle is a flat small muscle located deep in the buttock lying under the cover of the gluteus maximus (the large muscle that gives the buttocks its shape). With piriformis syndrome it is believed that the piriformis muscle irritates or compresses the proximal sciatic nerve due to contracture and/or spasm of the piriformis causing neuritis (inflammation of the nerve). The result of this is the individual may experience pain, numbness and tingling along the back of the leg and into the foot, similar to that felt with true sciatic pain.
Anatomy Of The Piriformis Muscle
The piriformis muscle originates mostly from the sacrum which is the base of the spine connecting to the upper surface of the femur (thigh bone). Specifically going from the front of the S2-S4 vertebrae to insert on the greater trochanter of the femur.
The function of the muscle is to help in rotating the hip outwards known as external rotation and abducting the hip away from the body. With the exact action piriformis creates on the joint being dependent on the position of the hip. By having a roll in abduction and rotation at the hip, piriformis can be considered to be a stabilizer of the hip joint.
Piriformis And The Sciatic Nerve
The sciatic nerve runs vertically directly beneath piriformis, however variations in the anatomy between individuals exists. It is estimated that in approximately 20% of people, the muscle belly of piriformis is split and 1 or more parts of the sciatic nerve divide the muscle belly itself rather than passing beneath as per the norm.
These anatomical variations between the sciatic nerve in the pelvis and piriformis muscle have been observed but are not necessarily related to individuals being symptomatic. Meaning some people diagnosed with piriformis syndrome have been shown to have the anatomically more common path for the sciatic nerve where it passes below the muscle and conversely the presence of a piriformis muscle divided by the sciatic nerve is not a guarantee someone will experience the symptoms of piriformis syndrome. This is one of the reasons that piriformis syndrome is considered a controversial diagnosis of buttock pain and sciatica symptoms.
Disclaimer: Sydney Physio Clinic provides this information as an educational service and is not intended to serve as medical advice. Anyone seeking specific advice or assistance on What Is Piriformis Syndrome? should consult his or her general practitioner, physiotherapist, sports medicine specialist, orthopedic surgeon or otherwise appropriately skilled practitioner.