Lateral Cutaneous Nerve of the Thigh

Nerves of the Lower Limb

• The lumbar plexus is formed by the ventral rami of L1-L4 and gives rise to six branches.
• The sacral plexus is formed by the ventral rami of S1-S4 and the lumbosacral trunk, and gives rise to seven branches.

Lumbar Plexus

• Ilio-Hypogastric Nerve (L1): motor and sensory innervation to the abdominal wall.
• Ilio-Inguinal Nerve (L1): sensory innervation to the scrotal region.
• Genitofemoral Nerve (L1,2): motor innervation to the cremaster muscle, sensory innervation to the scrotal region.
• Lateral Cutaneous Nerve of the Thigh (L2,3): sensory innervation to the anterolateral side of the thigh.
• Femoral Nerve (L2,3,4):
  • Motor innervation to the iliacus, pectineus, quadriceps, and sartorius muscles.
  • Sensory innervation to the anterior and medial aspects of the thigh, and the medial side of the leg and foot up to the ball of the big toe.
  • Articular innervation to the hip and knee joints.
• Obturator Nerve (L2,3,4):
  • Motor innervation to the obturator externus and adductors of the thigh.
  • Sensory innervation to the medial side of the thigh.
  • Articular innervation to the hip and knee joints.

Sacral Plexus

• Sciatic Nerve (L4-S3):
  • The thickest nerve in the body.
  • Forms from the lumbosacral trunk and exits the pelvis through the greater sciatic foramen.
  • Divides into the tibial nerve and common peroneal nerve in the popliteal fossa.
• Superior Gluteal Nerve:
  • Exits the pelvis through the greater sciatic foramen superior to the piriformis muscle.
  • Innervates the gluteus medius, gluteus minimus, and tensor fasciae latae.
• Inferior Gluteal Nerve:
  • Exits the pelvis through the greater sciatic foramen inferior to the piriformis muscle.
  • Innervates the gluteus maximus.
• Common Peroneal Nerve:
  • One of the two terminal branches of the sciatic nerve.
  • Divides into the superficial peroneal nerve and deep peroneal nerve.
• Deep Peroneal Nerve:
  • Supplies the muscles of the front of the leg and dorsum of the foot.
  • Sensory innervation to the adjacent sides of the big and 2nd toes.
  • Articular innervation to the ankle and foot joints.
• Superficial Peroneal Nerve:
  • Supplies the peroneus longus and brevis muscles.
  • Sensory innervation to the lower part of the anterolateral side of the leg and the dorsum of the foot.
• Tibial Nerve:
  • The larger of the two terminal branches of the sciatic nerve.
  • Runs vertically from the upper angle to the lower angle of the popliteal fossa.
  • Enters the sole of the foot by passing through the tarsal tunnel and divides into the medial and lateral plantar nerves.

Nerve Injuries

• Femoral Nerve Injury:
  • Causes: stab wounds, gunshot wounds.
  • Motor loss: weakness of knee extension and hip movements.
  • Sensory loss: anterior and medial aspects of the thigh.
• Obturator Nerve Injury:
  • Causes: stab wounds, anterior dislocation of the hip joint.
  • Motor loss: weak hip adduction.
  • Sensory loss: medial side of the thigh.
• Lateral Cutaneous Nerve Entrapment:
  • Causes: tight clothing, obesity, pregnancy, and diabetes.
  • Sensory loss: numbness and burning pain on the anterolateral side of the thigh.
• Superior Gluteal Nerve Injury:
  • Causes: penetrating trauma or surgery.
  • Motor loss: paralysis of hip abductors, positive Trendelenburg's sign.
• Inferior Gluteal Nerve Injury:
  • Causes: penetrating trauma or surgery.
  • Motor loss: weakness of hip extension and lateral rotation.
• Sciatic Nerve Injury:
  • Causes: wrong intramuscular injection in the gluteal region, posterior hip dislocation.
  • Motor loss: paralysis of hamstring muscles, weakness of knee flexion, and all muscles below the knee.
  • Sensory loss: below the knee downward (except the area supplied by the saphenous nerve).
• Common Peroneal Nerve Injury:
  • Causes: fracture of the neck of the fibula, pressure from casts or splints.
  • Motor loss: paralysis of muscles in the anterior and lateral compartments of the leg.
  • Sensory loss: anterolateral side of the leg (upper part) and the dorsum of the foot and toes (except the areas supplied by the sural and saphenous nerves).
• Tibial Nerve Injury at the Knee Joint:
  • Causes: posterior dislocation of the knee, fractures of the tibia and fibula, entrapment in soleus arch.
  • Motor loss: paralysis of muscles in the back of the leg and the sole of the foot.
  • Sensory loss: sole of the foot; trophic ulcers may develop.