Proximal Attachment
Piriformis arises as three digitations from the anterior surface of S2 to S4 between and lateral to the ventral sacral foramina, the gluteal surface of the posterior inferior iliac spine, the adjacent sacro-iliac joint capsule and the upper part of the pelvic surface of the sacrotuberous ligament.

Distal Attachment
The muscle emerges from the pelvis through the greater sciatic foramen with the fibers continuing to pass inferiorly, laterally and anteriorly narrowing into a tendon.  Its rounded tendon is attached to the medial side of the upper border and medial aspect of the greater trochanter of the femur, close to the insertion of the obturator internus and the gemelli, with which it may be partially merged.  It may also merge with the gluteus medius.