Ischium is a thick, rough-surfaced prominence below the lesser sciatic notch. This is the portion that supports weight while sitting (especially noticeable on a hard surface) and can be felt simply by sitting on the fingers. It serves as the origin for the inferior gemellus muscle and the hamstrings. The superior ramus is a partial origin for the internal obturator and the external obturator muscles. The inferior ramus serves partially as origin for part of the adductor magnus muscle and the gracilis muscle. The ischial ramus joins the inferior ramus of the pubis anteriorly and is the strongest of the hip
Mastoid part of the temporal bone the innermost of the mastoid cells by a very thin lamina of bone, and even this may be partly deficient. The "superior border" of the mastoid part is broad and serrated, for articulation with the mastoid angle of the parietal. The "posterior border", also serrated, articulates with the inferior border of the occipital between the lateral angle and jugular process. Anteriorly the mastoid portion is fused with the descending process of the squama above; below it enters into the formation of the ear canal and the tympanic cavity. A section of the mastoid process shows it to be hollowed out