Ischial spine

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Description:

The ischial spine is a pointed, triangular projection of variable length on the posterior margin of the ischium. Attaching to the apex of this projection is the sacrospinous ligament, which is the tendinous posterior edge of the ischiococcygeus muscle. The superior gemellus muscle attaches to its external surface and the levator ani and ischiococcygeus muscles attach to its internal surface. Its superior margin contributes to the greater sciatic notch, while its inferior margin contributes to the lesser sciatic notch.