Fig. 14-3. Oblique vertical section (see inset) to show relations in the gluteal region. Note that (A) a nerve and artery leave the greater sciatic notch superior to the piriformis, (B) seven nerves (the nerve to the quadratus femoris is not shown) and two arteries emerge inferior to the piriformis (see the list in the legend of fig. 14-2), and (C) two nerves and an artery regain the pelvis through the lesser sciatic foramen. The sciatic nerve lies successively on the ischium, gemelli and obturator internus, and quadratus femoris. (Modified from Castaing and Soutoul) Click for high resolution image.