Femoral nerve

Last revised by Craig Hacking on 18 Apr 2023

The femoral nerve is a large nerve arising from the lumbar plexus and one of two major nerves supplying the lower limb.

It arises from posterior divisions of L2-L4 roots of the lumbar plexus.

It emerges from the lateral border of the psoas muscle at its inferior aspect, before descending in between the lateral border of the psoas and medial border of iliacus muscles. It sends a motor branch to iliacus before passing under the inguinal ligament to enter the femoral triangle.

  • lies above iliacus, outside and lateral to the femoral sheath

  • gives off the nerve to pectineus, just after crossing the inguinal ligament

  • divides into anterior (superficial) and posterior (deep) divisions, separated by the lateral femoral circumflex artery

  • the terminal branch of the deep division reaches the apex of the femoral triangle to become the saphenous nerve

  • branches to iliacus muscle (prior to crossing inguinal ligament)

  • nerve to pectineus (immediately after crossing inguinal ligament)

Branches of the superficial division include:

  • nerve to sartorius

  • anterior femoral cutaneous nerves, which consist of:

    • medial femoral cutaneous nerve

    • intermedial femoral cutaneous nerve

  • sympathetic vasomotor supply to blood vessels

Branches of the deep division include:

The femoral nerve provides motor supply to the anterior compartment of the thigh and sensory supply to the hip, anterior and medial thigh, knee, and medial leg (as the saphenous nerve).

  • femoral nerve splits into two or three separate slips within the psoas muscle but unites to descend as a single bundle 2

  • accessory femoral nerve: fibers arise separately in lumbar plexus, passes anterior to femoral nerve, may terminate as saphenous nerve / cutaneous branch

  • femoral branch replacing lateral femoral cutaneous nerve which usually branches directly off lumbar plexus

  • saphenous nerve terminating  at knee with distribution replaced by branch of the tibial nerve

Femoral nerve is endangered by trauma. Injury results in weakness of knee extension and numbness overlying the anterior/medial thigh and medial leg.

The femoral nerve is responsible for the patellar tendon reflex (tests L3-L4 spinal component)

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Cases and figures

  • Figure 1: lumbar plexus labeled
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  • Figure 2: femoral nerve
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  • Figure 3: lumbar plexus (Gray's illustrations)
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  • Figure 4: lumbar plexus (Gray's illustrations)
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  • Figure 5: femoral triangle (diagram)
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