Femoral Nerve: Anatomy, Function, & Lesions

Femoral Nerve Anatomy

• Originates from the lumbar plexus (L2-L4).
• Travels through the psoas major, behind the inguinal ligament, and through the femoral triangle.
• Branches into articular branches for the hip and knee, motor branches for the anterior thigh, and sensory branches for the thigh and leg.

Femoral Nerve Motor Function

• Innervates the iliacus, pectineus, sartorius, rectus femoris, vastus medialis, vastus lateralis, and vastus intermedialis muscles.

Femoral Nerve Sensory Function

• The lateral cutaneous nerve supplies the anterolateral thigh.
• The saphenous nerve supplies the anteromedial thigh and leg.

Causes of Femoral Nerve Lesions

• Can be neuropraxia, axonotmesis, or neurotemesis.
• Femur or pelvic bone fractures can cause lesions.
• Surgeries can cause lesions.
• Compression from the iliopsoas or inguinal ligament can cause lesions.
• Space-occupying lesions can cause compression.

Femoral Nerve Lesion Signs & Symptoms

• Presents as quadriceps weakness, loss of patellar deep tendon reflex (DTR) (L4), loss of coordination in walking/running, loss of knee extension and some hip flexion, and muscle wasting.
• Sensory symptoms manifest as altered sensation in the anteromedial thigh, medial lower leg, and foot.
• Pain is usually at the inguinal ligament.

Femoral Nerve Assessment

• Includes patellar DTR assessment and manual muscle testing (MMT) of quadriceps, pectineus, sartorius, and iliacus.
• Sensory assessment should be performed in affected areas.
• The prone knee bending test biases the femoral nerve.
• The prone knee extension test biases the saphenous nerve.
• Side-lying passive knee flexion and hip extension describe the femoral nerve traction test.

Meralgia Paresthetica

• Compression of the lateral femoral cutaneous nerve (posterior division of ventral rami L2-L3).
• Compressed usually at the inguinal ligament.
• Trauma, pregnancy/birth with hips in flexion, tight clothing, heavy equipment belts, and inguinal hernia repair are causes.

Meralgia Paresthetica Signs & Symptoms

• Presents with no motor deficits.
• Manifests as sensory symptoms in the upper, lateral thigh: numbness, paresthesia, and burning pain.
• Usually unilateral.
• Aggravated by walking, standing, relieved by sitting/slackening tissue around the inguinal ligament.
• Trigger points may be present in the vastus lateralis, vastus intermedius, TFL, and gluteus medius.

Meralgia Paresthetica Differential Diagnosis

• Includes L2 radiculopathy and lumbar cutaneous nerve injury.

Meralgia Paresthetica Precautions

• Avoid further irritation to the nerve.
• Avoid increasing symptoms.
• Do not mobilize an axonotmesis or neurotmesis, where there are persistent, severe symptoms.

Meralgia Paresthetica Assessment

• Sensory assessment in nerve distribution is required.
• Tinel's test involves tapping at the inguinal ligament, medial to ASIS, to elicit tingling.
• The pelvic compression test involves deep palpation over the inguinal ligament.
• Hip extension may exacerbate symptoms.

Meralgia Paresthetica Treatment

• Aims to focus on decompression in a relaxation context.
• Inguinal ligament release.
• Myofascial Release (MFR).
• Techniques targeting the quads, sartorius, and iliacus.
• Pillow legs into hip flexion may be used.
• Includes sensory stimulation and ADL modifications.
• Posterior pelvic tilt aims to slacken the inguinal ligament.

Restless Leg Syndrome

• Characterized by noxious sensation in the leg, absent of external stimuli.
• Neurological disorder that causes burning, creeping, or tugging sensations.
• An irresistible impulse to move or shift for relief.
• Often worse in the evening or at night, or during long periods of rest.

Restless Leg Syndrome Etiology

• Idiopathic, but may have a genetic component with 50% of cases having a familial connection.
• Women are more affected than men.
• Usually affects older adults.
• Possible associations include iron, vitamin B12, and folic acid deficiency, kidney failure, diabetes, Parkinson's, peripheral neuropathy, and pregnancy.
• May be aggravated by stimulants such as coffee, alcohol, and tobacco.

Restless Leg Syndrome Treatment

• Massage focused on relaxation.
• Decreased stimulant consumption.
• See MD to assess nutritional deficiencies.
• Maintaining good sleep hygiene.
• Regular exercise performed not too close to bedtime.
• Warm or cool hydrotherapy, avoiding extreme temperatures.

Lateral Femoral Cutaneous Nerve Anatomy

• Comes from the lumbar plexus (L2-L3).
• It is a sensory nerve without motor fibers.
• Located between the ASIS and femoral nerve.
• More lateral and close to the ASIS; the femoral nerve is typically in the middle of the ASIS and the pubis, just lateral to the femoral artery.

Lateral Femoral Cutaneous Nerve Function

• Sensory provides sensation to the skin over the lateral thigh.

Meralgia Paresthetica (Lateral Femoral Cutaneous Nerve Compression Condition)

• A compressive mononeuropathy presenting as burning pain in the anterolateral thigh.
• Typically an entrapment at the inguinal ligament.
• Alleviating compression is key to treatment, often below the inguinal ligament as the nerve travels through a fibrous tunnel to emerge from the pelvis, or from tight clothes/belts/equipment.
• Treatment includes surgical decompression, injections (steroid or nerve block), conservative management such as weight loss, physiotherapy, and massage therapy.

Meralgia Paresthetica Grades of Injury

• Can be any grade of nerve injury.
• Neuropraxia normally results from internal compression from soft tissue or external compression from clothes/belts/equipment.
• Axonotmesis or neurotmesis normally results from iatrogenic MOI, such as post-surgery/injections, or due to the presence of pathology such as diabetes or other metabolic pathologies.

Meralgia Paresthetica Etiology

• Most common cause is entrapment at the inguinal ligament.
• Trauma from a Seat belt in MVA.
• Pregnancy; delivery is a cause with hips in flexion.
• Tight clothing can lead to this condition.
• Surgery like hernia repair.
• Incidence is much higher in people with diabetes.

Meralgia Paresthetica Signs and Symptoms

• Symptoms occur in the upper lateral thigh: numbness, paresthesia, burning pain.
• Aggravated by walking & standing. Sitting relieves symptoms.
• Usually unilateral.

Meralgia Paresthetica Differential Diagnosis

• Trigger points in the vastus lateralis, vastus intermedius, gluteus minimus, and TFL.
• Radiculopathy (L2 dermatome).
• Lumbar cutaneous nerves (iliohypogastric, subcostal) will have associated low back pain wrapping around obliques and be more proximal than the LFC distribution.

Meralgia Paresthetica Precautions

• Working in the area may exacerbate symptoms if it is very badly irritated, without causing damage or delaying recovery.
• Avoid applying pressure in the area of the nerve that increases symptoms
• Do not attempt to mobilize the nerve if recreate/produce symptoms which persist when remove pressure, stop trying direct decompression

Meralgia Paresthetica Treatment Techniques

• Techniques should be modified to suit stage of healing and severity of condition/presentation. The more acute or severe, the less direct attempts to decompress/mobilize tissue
• Skin rolling the entire lateral thigh is beneficial.
• Cross-hands around ilium / inguinal ligament and abdomen.
• Address active TrP which refer into area.
• Bow inguinal ligament.
• Thigh 3D wringing either supine or supine with flexion.
• Side-lying lift skin and mobilize nerve (hip flex-ext).
• Supine lift skin and mobilize nerve (knee flex-ext).

Meralgia Paresthetica Homecare

• Modify ADLs to address external compression sources (clothes, belts, equipment).
• Encourage posterior tilt of pelvis to slacken the inguinal ligament.
• Lift skin and flex hip standing.