What are the major nerves that innervate the lower limb?

The major nerves are derived from the lumbar (L1–L4) and sacral (L4–S4) plexuses. They include the femoral nerve for the anterior thigh, obturator nerve for the medial thigh, sciatic nerve for the posterior thigh and leg/foot, tibial nerve for the posterior leg and sole, and common peroneal nerve for the lateral and anterior leg.

What happens if the sciatic nerve is injured?

Sciatic nerve injury can cause foot drop and a flail foot, leading to difficulty walking. It also results in sensory loss in most of the leg and foot, except for the area supplied by the saphenous nerve.

How does a femoral nerve injury affect movement and sensation?

A femoral nerve injury weakens thigh flexion and causes loss of knee extension due to quadriceps involvement. Sensory loss occurs in the anterior and medial thigh, as well as the medial leg and foot.

What is the difference between dermatomes and peripheral nerve distributions in the lower limb?

Dermatomes are skin areas supplied by a single spinal nerve (e.g., L1–S3), used to diagnose spinal cord lesions. Peripheral nerve distributions involve specific named nerves (e.g., femoral or tibial) and show patchy sensory deficits when injured.

What muscles does the tibial nerve innervate?

The tibial nerve innervates all posterior leg muscles (like the calf muscles) and all intrinsic muscles of the sole. This allows for plantar flexion and toe flexion movements.

What are common clinical conditions related to lower limb nerve injuries?

Common conditions include foot drop from common peroneal nerve injury, tarsal tunnel syndrome from tibial nerve compression, Morton’s neuroma affecting digital nerves between toes, and paraplegia diagnosis using dermatomal testing.

Which spinal segments contribute to the innervation of the lower limb?

The lower limb is innervated by spinal segments from L1 to S4. Specifically, the lumbar plexus (L1–L4) and sacral plexus (L4–S4) give rise to the major nerves supplying motor, sensory, and articular functions.

Lower Limb Innervation – Major Nerves & Dermatomes

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