The Femoral Nerve

Author: Dr Krupa Samani

Last modified: May 17, 2014

The femoral nerve is one of the major nerves supplying the lower limb. In this article, we shall look at the anatomical course of the nerve, its motor and sensory functions, and any clinical relevance.

Once you have finished reading this article, try out our quick quiz at the bottom of the page to see how much you’ve learnt!


Overview

  • Nerve Roots: L2-L4
  • Motor: Innervates the anterior thigh muscles that flex the hip joint (pectineus, iliacus, sartorius) and extend the knee (quadriceps femoris: rectus femoris, vastus lateralis, vastus medialis and vastus intermedius)
  • Sensory: cutaneous branches to the anteromedial thigh (anterior cutaneous branches of the femoral nerve) and a terminal cutaneous branch supplies the medial side of the leg and foot (saphenous nerve)

Anatomical Course

Fig 1.0  - Course of the of the Femoral Nerve through the Femoral Triangle (In Red)

Fig 1.0 – Course of the of the Femoral Nerve through the Femoral Triangle (In Red)

The femoral nerve is the largest branch of the lumbar plexus. The nerve roots of the femoral nerve are L2 – L4.

The nerves descend from the lumbar plexus in the abdomen through the psoas major muscle. The nerve then travels through the pelvis to approximately the mid point of the inguinal ligament. It then traverses behind the inguinal ligament into the thigh and splits into an anterior and posterior division.

It passes through the femoral triangle lateral to the femoral vessels (enclosed within the femoral sheath) and gives off articular branches to the hip and knee joints.

The terminal cutaneous branch of the femoral nerve is the saphenous nerve which continues, with the femoral artery and vein, through the adductor canal.


Clinical Relevance: Arterial or Venous Sampling from the Femoral Vessels

If arterial or venous sampling is required from the femoral artery or vein respectively, it is essential to be aware of the order in which the structures lie.

Remembering ‘NAVY’ gives a reminder of the structures from LATERAL to MEDIAL

Lateral - Femoral NERVE - Femoral ARTERY - Femoral VEIN Medial


Motor Functions

The Femoral Nerve supplies some of the muscles of the anterior thigh 

Hip Flexors:

  • Pectineus. Actions: adducts and flexes the thigh, assists with medial rotation of the thigh
  • Iliacus. Actions: acts with psoas major and psoas minor (forming iliopsoas) to flex the thigh at the hip joint and stabilise the hip joint
  • Sartorius. Actions: flexes, abducts and laterally rotates the thigh at the hip joint. Flexes the leg at the knee joint

Knee Extensors:

  • Quadriceps Femoris: Rectus Femoris, Vastus Lateralis, Vastus Intermedius. Actions: extend the leg at the knee joint. Rectus femoris also steadies the hip joint and assists iliopsoas in flexing the thigh

Sensory Functions

The first cutaneous branches of the femoral nerve are the anterior cutaneous branches that arise in the femoral triangle. They supply the skin on the anteromedial thigh.

The last cutaneous branch of the femoral nerve is the saphenous nerve which supplies the skin on the medial side of the leg and the foot.

Fig 1.2 - Cutaneous branches of the Femoral Nerve

Fig 1.2 – Cutaneous branches of the Femoral Nerve


Clinical Relevance: Disorders of the Femoral Nerve

Stripping of the Saphenous Vein

The saphenous vein is often stripped in individuals with problematic varicose veins. The long saphenous vein is accompanied in it’s course by the saphenous nerve. Damage to the saphenous nerve during this procedure can lead to pain, paraesthesia or complete loss of sensation the medial side of the lower leg (please see Fig. 2 above for distribution)

Femoral Nerve Block

Femoral nerve block (in combination with a sciatic nerve block) may be indicated in patients requiring lower limb surgery who cannot tolerate a general anaesthetic. A femoral nerve block can also be used as peri and post operative analgesia for patients with a fractured neck of femur who cannot tolerate particular analgesics.


Anatomy of the Femoral Nerve Quiz

Once you have looked over the Anatomy of the Femoral Nerve article, this quiz allows you to test your knowledge and provides immediate feedback.