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
Hip bone the seventh or eighth year, the inferior rami of the pubis and ischium are almost completely united by bone. About the thirteenth or fourteenth year, the three primary centers have extended their growth into the bottom of the acetabulum, and are there separated from each other by a Y-shaped portion of cartilage, which now presents traces of ossification, often by two or more centers. One of these, the os acetabuli, appears about the age of twelve, between the ilium and pubis, and fuses with them about the age of eighteen; it forms the pubic part of the acetabulum. The ilium