The femoral nerve originates from the lumbar plexus and is composed of the anterior and posterior branches of the lumbar 2, 3, and 4 nerves. It passes through the outer edge of the psoas major muscle, runs obliquely downward on the deep surface of the iliac fascia, reaches the femoral fascial sheath between the psoas major and the iliacus muscles, and sends out iliac and psoas muscle branches in the iliac fossa. The main trunk passes through the deep surface of the inguinal ligament and the surface of the iliopsoas muscle, enters the femoral triangle through the intermuscular space, and is located on the outside of the femoral artery. The femoral nerve passes through the posterior 2 to 3 cm of the groin and divides into anterior and posterior branches. The anterior branch is further divided into the medial femoral cutaneous nerve and the intermediate femoral cutaneous nerve, which innervate the skin of the anterior medial thigh and send out motor branches to innervate the sartorius muscle and the pectineus muscle; the posterior branch first divides into muscle branches to the quadriceps femoris, and then divides into a cutaneous nerve, namely the saphenous nerve. The saphenous nerve enters the adductor canal from the femoral triangle along with the femoral artery and vein, passes through the fascia at the lower end of the canal, is located behind the sartorius muscle at the knee, and then runs subcutaneously and accompanies the great saphenous vein to the medial malleolus.