The femoral nerve is a branch of the lumbar plexus, composed by L1, L2, L3, and L4 spinal roots. The femoral nerve runs along the margin of the greater psoas muscle up to the inguinal ligament and underneath it through the muscular lacuna to the front of the thigh. The nerve trunk divides below the inguinal ligament into several branches, namely, a mostly sensory group, the anterior cutaneous branches, a lateral and medial group of motor branches for the extensor muscles of the thigh, and the saphenous nerve. The saphenous nerve extends to the adductor canal and enters into it. It penetrates the vastoadductor membrane and runs along the medial side of the knee joint and the lower leg together with the great saphenous vein down to the medial ankle. In the small pelvis, the femoral nerve gives off fine branches to the greater psoas muscle and to the iliac muscle. Below the inguinal ligament, a branch extends to the pectineal muscle. The anterior cutaneous branches originate slightly more distally, with the strongest one continuing along the middle of the thigh down to the knee. They supply sensory fibers to the skin of the anterior and medial aspects of the thigh.