ANATOMY
The sciatic nerve is the largest nerve in the human body, originating from the lumbosacral plexus (L4-5 and S1-3) and providing sensory and motor innervation to the lower extremity. The sciatic nerve exits the pelvis via the greater sciatic foramen below the piriformis muscle. In the gluteal region, the sciatic nerve courses between muscle layers. The nerve is deep (anterior) to the gluteus maximus muscle and is superficial (posterior) to the inner muscle layers (superior and inferior gemellus muscles, obturator internus muscle, quadratus femoris muscle).
It courses down the midline of the posterior thigh and branches into the tibial and common peroneal nerves usually in the popliteal fossa. Sciatic nerve block is most commonly performed for foot or ankle surgery
