Inseion of needle at upper lateral quadrant of gluteal region doesn't injure nerves Needle inseion at lower medial quadrant damages sciatic and pudendal nerves Needle inseion at sacrospinous ligament damages pudendal nerves and vessels Needle inseion at the midway between ischial tuberosity and lesser trochanter damages sciatic nerve, posterior femoral cutaneous nerves. Ref: Gray's Anatomy The Anatomical Basics of Clinical Practice 41 e pg 1373.