Within the buttock:

• A. the pudendal nerve emerges beneath piriformis, turns around the back of the sacrospinous ligament and passes between the sacrotuberous and sacrospinous ligaments
• B. the internal pudendal artery can be compressed against the base of the ischial tuberosity
• C. the sciatic nerve (L4, 5, S1) emerges from below piriformis muscle more laterally than the inferior gluteal and pudendal nerves and vessels
• D. the posterior femoral cutaneous nerve lies medially to the sciatic nerve
• E. the cruciate anastomosis provides the main source of blood for the supply of the head of femur