The piriformis muscle has its origin upon the front surface of the sacrum, and inserts onto the greater trochanter of the femur.

[1] The piriformis muscle originates from the anterior (front) surface of the sacrum[2][3] by three fleshy digitations attached to the second, third, and fourth sacral vertebra.

[1] It also arises from the superior margin of the greater sciatic notch,[4] the gluteal surface of the ilium (near the posterior inferior iliac spine), the sacroiliac joint capsule, and (sometimes) the sacrotuberous ligament (more specifically, the superior part of the pelvic surface of this ligament).

The anterior surface of the muscle is related to the rectum (especially on the left side of the body), and the sacral plexus.

[2] Several variations occur, one of which is the rarely found Beaton's type-b where the sciatic nerve divides between and below the piriformis.

[2] Abduction of the flexed thigh is important in the action of walking because it shifts the body weight to the opposite side of the foot being lifted, which prevents falling.

Findings suggest the possibility that Botulinum toxin type B may be of potential benefit in the treatment of pain attributed to piriformis syndrome.

As it travels through the greater sciatic foramen, it effectively divides it into an inferior and superior part.

[10] The piriformis muscle was first named by Adriaan van den Spiegel, a professor from the University of Padua in the 16th century.