The femoral nerve is a nerve in the thigh that supplies skin on the upper thigh and inner leg, and the muscles that extend the knee. The femoral nerve is the largest branch of the lumbar plexus. It is derived from the anterior rami of nerve roots L2, L3 and L4. The femoral nerve is the largest branch of the lumbar plexus. The nerve descends from the lumbar plexus in the abdomen, travelling down through the fibres of psoas major. The nerve exits psoas major at the lower part of its lateral border, passing behind the iliac fossa to approximately the mid-point of the inguinal ligament. It then traverse below the inguinal ligament of about 4 cm into the thigh and splits into an anterior and posterior division.The lateral circumflex femoral artery is straddled by both sections. The nerve enters the femoral triangle by passing beneath the inguinal ligament, just lateral to the femoral artery. In the thigh, it lies outside the femoral sheath , gives off articular branches to the hip and knee joints. The terminal cutaneous branch of the femoral nerve is the saphenous nerve  which continues, with the femoral artery and vein, through the adductor canal.