Sciatic nerve: a shape 76%, b shape 24% (Anson BJ classification); 2% has a branch going through piriformis muscle; 76% divides out gluteal region, 24% divides in gluteal region; 22% at internal third, 63% at medial third, 15% at external third of piriformis muscle; mean diameter 15.2 ± 2.4 mm, mean length 331 ± 24 mm, and has 5 ± 1 branches.