Femoral Nerve

Origin

The femoral nerve is a branch of the lumbar plexus. It is formed by the union of the posterior divisions of anterior rami of the second to fourth lumbar nerves (Moore, Dalley and Agur, 2013), within the substance of the psoas major muscle (Note: The anterior divisions contribute to the obturator nerve).

Course

The femoral nerve descends through the substance of psoas major muscle, emerging from the lower lateral border of the muscle. Continuing its descent, the femoral nerve lies between psoas major and iliacus muscles. It travels over the anterior surface of iliacus, while lying deep to the iliacus fascia. It is situated lateral to the femoral artery as it passes underneath the inguinal ligament to enter the anterior compartment of the thigh (femoral triangle region) (Moore, Dalley and Agur, 2013).

Branches

The femoral nerve sends a motor branch to iliacus muscle (L2—L3) before passing underneath the inguinal ligament. Upon entering the anterior compartment of the thigh, it gives a motor branch to pectineus (L2—L3), subsequently the nerve gets separated into a superficial and deep division by the lateral circumflex femoral artery.

The branches of the superficial division include the motor nerve to the sartorius muscle (L2—L3) and anterior femoral cutaneous nerves (L2—L3), which are distributed along the skin of the anterior and medial surfaces of the thigh.

The deep division gives off motor branches to the quadriceps muscles (L3—L4), including rectus femoris, vastus intermedius, vastus medialis, and vastus lateralis muscles. The terminal branch of the deep division travels below sartorius inside the adductor canal. It reaches the apex of the femoral triangle (at the junction of sartorius and adductor longus) where it continues distally as the cutaneous saphenous nerve (L3—L4). This nerve provides sensory innervation to the skin on the medial surface of the leg and medial side of the ankle and the foot. In addition, sensory articular branches also innervate the hip and the knee joints.

Supplied Structures

Muscular branches of the femoral nerve supply iliacus, pectineus, sartorius, rectus femoris, vastus medialis, vastus intermedius, and vastus lateralis muscles.

The anterior cutaneous branches supply the skin on the anterior and medial surface of the thigh. The saphenous nerve supplies the skin on the medial surface of the leg, ankle, and foot. Finally, sensory articular innervation is supplied to the hip and knee joints.

List of Clinical Correlates

—Patellar tendon reflex

—Femoral nerve neuropathy

References

Moore, K. L., Dalley, A. F. and Agur, A. M. R. (2013) Clinically Oriented Anatomy. Clinically Oriented Anatomy 7th edn.: Wolters Kluwer Health/Lippincott Williams & Wilkins.