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The pear-shaped muscle
Last reviewed: 04.07.2025
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The piriformis muscle (m piriformis) originates on the pelvic surface of the sacrum (II-IV sacral vertebrae), lateral to the pelvic sacral openings, and exits the cavity of the lesser pelvis through the greater sciatic opening. Behind the neck of the femur, the muscle passes into a round tendon that attaches to the apex of the greater trochanter. Under this muscle is the synovial bursa of the piriformis muscle (bursa synovialis musculi piriformis).
Function of the piriformis muscle: rotates the thigh outward with slight abduction.
Innervation of the piriformis muscle: muscular branches of the sacral plexus (SI-SIII).
Blood supply of the piriformis muscle: inferior gluteal, obturator, internal pudendal artery.
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