Piriformis muscle

Piriformis muscle
Buttocks seen from behind (the piriformis and the rest of the lateral rotator group are visible)
Muscles of the gluteal and posterior femoral regions seen from the front.
Details
Origin	Sacrum
Insertion	Greater trochanter
Artery	Inferior gluteal , lateral sacral and superior gluteal artery,
Nerve	Nerve to the piriformis (L5, S1, and S2)
Actions	External rotator of the thigh
Identifiers
Latin	Musculus piriformis
TA	A04.7.02.011
FMA	19082
Anatomical terms of muscle []

The piriformis (from Latin piriformis = "pear shaped") is a muscle in the region of the lower limb. It is one of the six muscles in the lateral rotator group.

It was first named by Adriaan van den Spiegel, a professor from the University of Padua in the 16th century.

The piriformis muscle originates from the anterior (front) part of the sacrum, the part of the spine in the gluteal region, and from the superior margin of the greater sciatic notch (as well as the sacroiliac joint capsule and the sacrotuberous ligament). It exits the pelvis through the greater sciatic foramen to insert on the greater trochanter of the femur. Its tendon often joins with the tendons of the superior gemellus, inferior gemellus, and obturator internus muscles prior to insertion.

The piriformis is a flat muscle, pyramidal in shape, lying almost parallel with the posterior margin of the gluteus medius.

It is situated partly within the pelvis against its posterior wall, and partly at the back of the hip-joint.