Greater sciatic notch

Above the ischial spine is a large notch, the greater sciatic notch, converted into a foramen by the sacrospinous ligament

It transmits the Piriformis, the superior and inferior gluteal vessels and nerves, the sciatic and posterior femoral cutaneous nerves, the internal pudendal vessels, and nerve, and the nerves to the Obturator internus and Quadratus femoris.

Of these, the superior gluteal vessels and nerve pass out above the Piriformis, the other structures below it.