The sciatic nerve is composed of L4, 5 and S1-3 nerve roots. It is the thickest nerve in the body, with a diameter of about 15mm at the beginning. It passes through the greater sciatic foramen and out of the pelvis. The sciatic nerve generally passes through the inferior foramen of the piriformis muscle to the buttocks. In a few cases (36.21%), the sciatic nerve is divided into two strands, one passing through the piriformis muscle and the other exiting the inferior foramen of the piriformis muscle; there are also cases where the sciatic nerve is divided into multiple strands and exits the pelvis. After entering the buttocks, it is located on the surface of the obturator internus, upper and lower gemelli and quadratus femoris muscles, and is covered by the gluteus maximus. This is the most superficial part of the sciatic nerve in the buttocks. This section has no thicker branches, the surrounding tissue is loose, and it is close to the hip joint. Intramuscular injection, hip dislocation, pelvic fracture, etc. are all prone to cause sciatic nerve damage at this location. In its loose connective tissue sheath, the tibial nerve is located on the inner and posterior side, and the common peroneal nerve is located on the anterolateral side. The tibial nerve is thicker than the common peroneal nerve. The sciatic nerve runs outward and downward in an arc shape, descending at the intersection of the inner 1/3 of the line connecting the sciatic tuberosity and the greater trochanter. This point is often used in clinical practice to check the tenderness of the sciatic nerve. The sciatic nerve goes down vertically and divides into two tibial and peroneal branches at the lower 1/3 of the femur. The branching point of the sciatic nerve varies greatly. Some are divided into two branches by the sacral plexus, while others are divided into two branches at the lower part of the thigh.