This is the large rough surface on the posterior aspect of the ischium. Its wider upper half provides attachment for the muscles of the posterior thigh, the semimembranosus, semitendinosus, and the long head biceps femoris. The tapering inferior half is rough and serves as an attachment site laterally for fibers of the adductor magnus and medially for the sacrotuberous ligament. Near its upper medial border is the attachment site of the inferior gemellus muscle.

Tuberosity is derived from the Latin term tuber meaning a lump. The -osity ending denotes many or to be full of something. This term then literally translates as having lots of lumps.

Tuber ischiadicum

Tubérosité ischiatique