Femoral Nerve: The femoral nerve is one of the major peripheral nerves 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 segment of the lumbar plexus and originates from the dorsal divisions of the ventral rami of the second, third, and fourth lumbar nerves (L2-L4).
Sensory: Supplies cutaneous branches to the anteromedial thigh (anterior cutaneous branches of femoral nerve) furthermore the medial side of the leg and foot (saphenous nerve).
Motor: Supplies the anterior thigh muscles that flex the hip joint (iliacus, pectineus, Sartorius) and extend the knee (quadriceps femoris muscles).
Anatomical Course of the Femoral Nerve
It penetrates into the fibers of the psoas major, emerging from the muscle at the lower part of its lateral border, and crosses down within it and the iliacus muscle, behind the iliac fascia; it later runs beneath the inguinal ligament, within the thigh, and divides into an anterior and a posterior division. It crosses within the femoral triangle lateral to the femoral vessels and gives off articular branches to the hip and knee joints.The terminal cutaneous branch of the femoral nerve is the saphenous nerve that continues, with the femoral artery and vein, within the adductor canal.
Under the inguinal ligament, it is separated from the femoral artery by a portion of the psoas major muscle.
Functions of the Femoral Nerve
The femoral nerve supplies some of the muscles of the anterior thigh
Pectineus Muscle – adducts and flexes the thigh, assists with medial rotation of the thigh.
Iliacus Muscle – acts with psoas major and psoas minor (forming iliopsoas) to flex the thigh at the hip joint and stabilize the hip joint.
Sartorius Muscle – flexes, abducts and laterally rotates the thigh at the hip joint. Flexes the leg at the knee joint.(Knee Extensors)
Quadriceps femoris Muscles ( vastus lateralis, vastus intermedius, rectus femoris,) – extends the leg at the knee joint. Rectus femoris also steadies the hip joint and supports iliopsoas in flexing the thigh.
The first cutaneous sections of the femoral nerve are the anterior cutaneous that appear in the femoral triangle. They supply the skin on the anteromedial of the thigh.
The other cutaneous branch is the saphenous nerve that supplies the skin on the medial side of the leg and the foot.