Femoral Nerve

Femoral Nerve Location

The femoral nerve is located in the leg near the groin. The femoral nerve forms the largest branch of lumbar plexus and is associated both with motor and sensory function. The femoral nerve supplies out two muscular branches to the Psoas and Iliacus muscles.

Femoral Nerve Origin

The femoral nerve arises from the L2, L3 and L4 posterior divisions of the ventral rami in the lumbar region of the lower abdomen.

Femoral Nerve Function

1. Motor function: The femoral nerve provides motor innervation to the anterior compartment thigh muscles. The femoral nerve helps in hip muscle movement and straightening of the legs and this forms the motor function. The femoral nerve innervates the muscles which allow for the flexion of the hip and extension of the knee.
2. Sensory function: It provides sensory innervation to the skin of the anterior thigh. The sensory function of the femoral nerve is that it provides sensation to the front part of the thigh and lower part of the leg below the knee.

What is the course of the femoral nerve?

• The femoral nerve starts from the lumbar plexus in the abdomen and descends through the psoas major muscle.
• From here the femoral nerve passes deep into the inguinal ligament and then enters the thigh through the femoral triangle. In the femoral triangle, this nerve is laterally situated to the femoral artery.
• Placed distant and back from the inguinal ligament and under the Sartorius muscle, now the femoral nerve divides into branches where it gets terminated.
• The division of branches is into sensory and motor. The motor branches are Sartorius, quadriceps, and pectineus. The sensory branches are intermediate femoral cutaneous nerve, medial femoral cutaneous nerve, and the saphenous nerve.

Which branch of the femoral nerve is responsible for the sensory and motor innervation?

1. Sensory innervation: The area of sensory innervation is due to the medial femoral cutaneous nerve and the intermediate femoral cutaneous nerve. Also, the infrapatellar branch of the saphenous nerve and the saphenous nerve form the areas of innervation. The obturator nerve sensory innervation is not part of the femoral nerve innervation.
2. Motor innervation: The hip flexors formed by the iliacus, psoas, sartorius, and pectineus form the motor function of the femoral nerve.

Femoral Nerve Pictures

How is the femoral nerve injured?

1. The injury is usually caused by trauma which is the direct injury.
2. Another reason is when there is a prolonged pressure on the nerve.
3. When the femoral nerve gets compressed or trapped by structures such as a tumor in its nearby places, then there are possibilities of the nerve getting damaged.
4. Even when there is damage to the lumbar spine or the pelvis, it may result in the trauma of the femoral nerve.
5. The quadriceps tendon may get ruptured due to which there is a pain in the quadriceps muscle.
6. When there is hematoma of the pelvis, the saphenous nerve of the femoral nerve will be affected.
7. The iliopsoas region consists of the iliacus, psoas major and the psoas minor muscles. Here the hemorrhage in the pelvis and iliopsoas region may be caused by severe trauma, anticoagulation therapy, and hemophilia or any other diseases of the blood.
8. Some other causes for the femoral nerve damage are diabetes and damage to the nearby bones.

What are the symptoms of femoral nerve injury?

1. Loss of knee extension
2. Loss of hip flexion
3. Loss of sensation in areas where the sensory branches of the femoral nerve are located.

What is the femoral nerve stretch test?

The femoral nerve stretch test or the prone knee bending test is done for testing the motor function of the femoral nerve and to stress the lumbar (L2-L4) nerve roots. This is one of the most reliable techniques for assessment of the mid-lumbar (L2, L3, and L4) nerve root impingement.

The methodology performed is as follows:

1. The patient is made to lie down symmetrically on the bed.
2. The examiner places one hand on the patient’s pelvis so that there is no movement of the pelvis during the examination. This is done to stabilize the anterior pelvic rotation.
3. The other hand of the examiner is used to flex the involved knee as much as possible and maintain that position for about 45 seconds.

If the pain is found in the lumbar region, anterior or the posterior thigh, groin or the buttocks then the test is positive.

Results of the femoral stretch test

If the test is positive it indicates that the L2, L3, and L4 nerve roots are involved. When there are disc herniations it affects the L5- S1 nerve roots.

What is the importance of the femoral nerve stretch test?

The femoral nerve passes through the anterior side of the lower extremities in the leg. The stretch test knee position puts tension on the femoral nerve and its nerve roots. So when the test is positive it indicates injury to the L2-L4 nerve roots. But one important point to note here is that the femoral nerve stretch test solely will not be enough to prove the femoral nerve impingement. A combination of other tests is necessary for diagnosis.

What is the mode of treatment for femoral nerve injury?

1. Healing naturally: As doctors do not promote unnecessary surgical intervention, they leave it to heal by itself where there are possibilities. After the patient recovers, some exercises to improve mobility may be undertaken.
2. Surgical intervention: When surgical interventions are necessary like in case of removal of tumors or other growths which is pressing the femoral nerve, then it is advisable to go in for such removal techniques.
3. Medications: Medications may be administered either to reduce the inflammation and swelling or to reduce the pain.
4. Therapy: The other common treatment technique is the physical therapy and use of support structures where mobility is an issue.

Some common questions related to the femoral nerve:

Q1. What are the problems faced when there is a femoral nerve injury?

Answer: One of the main problems is the difficulty in climbing up or down the stairs. It hurts more when getting down the stairs. Added to the motor problem is the muscle weakness which may result in falls and injuries to the leg. The other problem is the numbness in the thigh, knee or the lower leg. There may be burning sensation or tingling in the leg. In case of loss of sensation, any injuries or wounds in that area may go unnoticed, so people with diabetes need to be extra cautious.

Q2. What are the tests that may be conducted other than the nerve stretch test?

Answer: The other tests include Electromyography (EMG), nerve conduction tests (NCV) and MRI to rule out tumors.

Q3. Will the patient recover completely after proper diagnosis and treatment for femoral trauma?

Answer: When there is a femoral injury, the main course of action would be proper diagnosis and its subsequent treatment after which a patient recovers successfully. But sometimes the conditions may be such that a full recovery is not possible. Then the patient may have partial loss of movement or loss of sensation.