Sciatic nerve consists of L4, 5 and S1, 2, 3 nerve roots. Most of the injuries are caused by firearm injuries to the femur or buttock, and sometimes hip dislocation and pelvic fracture can be combined with sciatic nerve injury. Causes of paralysis of the muscles below the thigh or knee Drug injection injury, especially penicillin injection, is the most common cause of sciatic nerve injury, also known as medical sciatic nerve injury, which occurs in children, the cause of the injury and the injection site of the inappropriate direct injury or too large a dose of drugs to stimulate the sciatic nerve; sharp force injury, acetabular fracture, pelvic fracture and hip dislocation, especially the posterior dislocation is also a common cause of sciatic nerve injury. Sciatic nerve injury is also a common cause. 1, sports: if the injury site in the sciatic foramen magnum or above the sciatic tuberosity, then the posterior femoral muscle group, calf anterior, external and posterior muscle groups and foot muscles are all paralyzed. If the injury occurs in the middle and lower part of the femur, the muscles below the knee will be paralyzed because the branch of the naevus muscle has been issued in large part. If the branch is injured, the muscles in the innervation area of the common peroneal nerve and tibial nerve are paralyzed. Sensation: Except for the saphenous nerve innervation area at the medial side of the calf and the inner ankle, sensation is lost in the area below the knee.