Anatomical Structure and Location of the Piriformis Muscle

Description

Arising from the anterior (pelvic) surface of the sacrum, the right piriformis courses laterally and anteriorly to exit the pelvis through the greater sciatic foramen, then tapers toward its insertion on the superior border of the greater trochanter of the femur. The sacrum and coccyx sit medial to the muscle’s origin, while the ilium and acetabular region lie lateral and superior, framing the posterior hip. Proximally, the piriformis is anchored to the sacral segments; distally, it approaches the femur just posterior to the hip joint capsule. Deep gluteal anatomy, simplified to emphasize the piriformis line of pull. This relationship matters because the piriformis is the key landmark of the greater sciatic foramen and the usual divider of neurovascular traffic in the deep gluteal region, with the sciatic nerve typically emerging inferior to it. Small changes in piriformis tone, hypertrophy, or anatomic variation (such as a split piriformis or a sciatic nerve division passing through the muscle belly) can reproduce buttock pain and sciatica-like symptoms, a common source of diagnostic confusion with lumbar radiculopathy. The depicted trajectory also explains why hip flexion and adduction can alter piriformis function, shifting from external rotation to abduction depending on hip position. Use this plate for gross anatomy lab teaching on the pelvis and hip, for PM and R anatomy lectures on deep gluteal pain syndromes, or as a clean reference figure in manuscripts discussing piriformis syndrome, image-guided injections, or posterior approaches to the hip. It also suits patient-facing education when explaining why posterior pelvic muscles can irritate the sciatic nerve. Anatomical accuracy verified by SciePro's Medical Advisory Board.