Nerve supply of the human leg

The nerve supply of the human leg is a complex network that provides motor and sensory innervation to the lower limb. This network is primarily derived from the lumbar plexus and the sacral plexus.

Lumbar Plexus

The lumbar plexus is formed by the anterior rami of the spinal nerves L1 to L4. It is located in the psoas major muscle and gives rise to several important nerves:

• The femoral nerve (L2-L4) innervates the anterior compartment of the thigh, providing motor function to the quadriceps femoris and sensory innervation to the anterior thigh and medial leg.
• The obturator nerve (L2-L4) supplies the medial compartment of the thigh, innervating the adductor muscles and providing sensory input to the medial thigh.

Sacral Plexus

The sacral plexus is formed by the anterior rami of the spinal nerves L4 to S4. It is located on the posterior pelvic wall and gives rise to several key nerves:

• The sciatic nerve (L4-S3) is the largest nerve in the body and innervates the posterior compartment of the thigh, the entire leg, and the foot. It divides into the tibial nerve and the common fibular nerve.
• The tibial nerve (L4-S3) innervates the posterior compartment of the leg and the sole of the foot.
• The common fibular nerve (L4-S2) divides into the superficial fibular nerve and the deep fibular nerve, which innervate the lateral and anterior compartments of the leg, respectively.

Clinical Relevance

Damage to the nerves supplying the leg can result in various clinical conditions:

• Sciatica is characterized by pain radiating along the path of the sciatic nerve.
• Femoral nerve dysfunction can lead to weakness in the quadriceps and loss of knee-jerk reflex.
• Common fibular nerve injury can cause foot drop, a condition where the patient is unable to dorsiflex the foot.

See Also

• Peripheral neuropathy
• Nerve injury
• Lower limb anatomy

External Links

• Lower limb anatomy on WikiMD