The Piriformis: Getting to the Bottom of It
Updated: May 26, 2022
The piriformis muscle is an important piece of the puzzle to rule out whenever assessing low back, hip, and/or lower extremity pain. When indicated, a correctly placed acupuncture needle into the piriformis can promote positive clinical outcomes. In many patients, palpation of this muscle can prove to be difficult. Precise needle depth is required to achieve the desired benefit when performing acupuncture locally to this muscle.
As a general rule, if you can palpate the piriformis clearly it is likely taut and hyperactive (1). Unfortunately, it is not always that simple. On occasion, body habitus can make efforts to isolate the piriformis seem trivial. There are many landmark techniques that have been reported in the literature which can be helpful in pinpointing this muscle correctly. A couple of examples have been listed below.
A) Draw a line from the PSIS to the greater trochanter of the femur. Reference points will lie at a distance of 1/3 and 2/3 along this line. Insertion points are located 1-3 cm below this reference line (2).
B) Follow the line connecting the PSIS and the superior aspect of the greater trochanter to locate the superior portion of the piriformis muscle belly. Divide the PSIS and sacral horn distance into thirds. The junction of the middle and lower thirds will be used to draw a line to the greater trochanter to locate the inferior portion of the piriformis muscle belly (3).