Ischium

The "ramus" of the ischium is the thin, flattened part of the ischium (lowest part of the coxal bone), which ascends from the lower part of the body and joins the inferior ramus of the pubis - the junction being indicated in the adult by a raised line. The combined rami are sometimes called the "ischiopubic ramus." The ischium is the posterior inferior compart of the pelvis. Posteriorly, bony prominences form the ischial tuberosity or each side of the inner pelvis and support the body's weight in a sitting position. The large opening called the obturator foramen is formed by both the rami of the ischium together with the pubis and creates the opening that allows for the passage of major blood vessels and nerves to the legs and feet.