This general sensory and motor nerve originates in the lumbar plexus, L2-L4, and descends behind the inguinal ligament to the femoral triangle. Its branches are the saphenous nerve and the muscular and anterior cutaneous rami. It distributes to the skin of the thigh and leg, the muscles of the front of the thigh, and the hip and knee joints.
The femoral nerve, the largest branch of the lumbar plexus, arises from the dorsal divisions of the second, third, and fourth lumbar nerves. It descends through the fibers of the Psoas major, emerging from the muscle at the lower part of its lateral border, and passes down between it and the Iliacus, behind the iliac fascia; it then runs beneath the inguinal ligament, into the thigh, and splits into an anterior and a posterior division. Under the inguinal ligament, it is separated from the femoral artery by a portion of the Psoas major.