Greater sciatic notch Greater sciatic notch The greater sciatic notch is a notch in the ilium, one of the bones that make up the human pelvis. It lies between the posterior inferior iliac spine (above), and the ischial spine (below). The sacrospinous ligament changes this notch into an opening, the greater sciatic foramen. The notch holds the piriformis, the superior gluteal vein and artery, and the superior gluteal nerve; the inferior gluteal vein and artery and the inferior gluteal nerve; the sciatic and posterior femoral cutaneous nerves; the internal pudendal artery and veins, and the nerves to the internal obturator and quadratus femoris
Hip bone pubic symphysis is present only in the ostrich, and the two hip bones are usually widely separated, making it easier to lay large eggs. In therapsids, the hip bone came to rotate counter-clockwise, relatives to its position in reptiles, so that the ilium moved forward, and the pubis and ischium moved to the rear. The same pattern is seen in all modern mammals, and the thyroid fenestra and obturator foramen have merged to form a single space. The ilium is typically narrow and triangular in mammals, but is much larger in ungulates and humans, in which it anchors powerful gluteal