Fig. 1. Illustration of the traditional pubic and the inguinal approach for obturator nerve block. In the pubic approach, the insertion point of the needle is 2 cm lateral and 2 cm inferior to the pubic tubercle. In the inguinal approach, the insertion point of the needle is at the midpoint of the line drawn between the femoral arterial pulse and the inner border of the adductor longus tendon. ( 1 ) Superior anterior iliac spine, ( 2 ) pubic tubercle, ( 3 ) inguinal ligament, ( 4 ) inguinal crease, ( 5 ) insertion point of needle in the pubic approach, ( 6 ) insertion point of the needle in the inguinal approach, ( 7 ) femoral pulse, ( 8 ) inner border of the adductor longus tendon .