Loss of sensation in the medial calf is one of the symptoms of a high level femoral nerve injury. Femoral nerve injury high injury manifests as loss of sensation in the anterior medial femur and medial calf. The following aspects can help the diagnosis of medial calf sensory loss: 1, motor factors: if the injury is above the iliac fossa, the iliopsoas muscle and quadriceps are paralyzed, showing the inability to flex the hip and knee extension, if the injury is below the iliopsoas branch, only showing the inability to extend the knee. 2, body sensation: high injury is manifested as the loss of sensation in the anterior medial femur and medial calf. Low-level injury, can be a simple saphenous nerve injury, performance of the medial calf sensory disorders. 3, external environmental factors: the medial calf is vulnerable to trauma, frostbite and burns. History of trauma, paralysis of iliopsoas muscle and quadriceps, inability to flex and extend the knee. Loss of sensation in the anterior femur, medial and medial calf, electromyography, helps to diagnose. The femoral nerve originates from the lumbar plexus and consists of the posterior femoral branch of the anterior branches of the lumbar 2, 3, and 4 nerves. It penetrates from the outer edge of the psoas major muscle, travels obliquely downward over the deep surface of the iliac fascia, reaches the femoral fascia sheath between the psoas major muscle and the iliacus muscle, and gives off the iliacus muscle branch and the psoas major branch in the iliac fossa. The trunk passes through the deep surface of the inguinal ligament, the surface of the iliopsoas muscle, and enters the femoral triangle by the muscle gap and lies lateral to the femoral artery. The femoral nerve crosses 2-3 cm behind the groin and divides into an anterior branch and a posterior branch. The anterior branch is divided into the medial femoral cutaneous nerve and the middle femoral cutaneous nerve, which innervate the anterior medial femoral skin and send out a motor branch to innervate the suture muscle and pubococcygeus muscle; the posterior branch first divides into a muscular branch to the quadriceps muscle, and then divides into a cutaneous nerve, the saphenous nerve, which accompanies the femoral artery and vein from the femoral triangle into the adductor canal, penetrates the fascia from the lower end of this canal, and lies in the knee The saphenous nerve accompanies the femoral artery and vein from the femoral triangle into the adductor canal, penetrates the fascia from the lower end of this canal, lies behind the suture muscle at the knee, and then travels subcutaneously with the saphenous vein to the medial ankle.