Lower Limb Nerve Plexuses and Innervation: Lumbar, Sacral, and Peripheral Nerves

Lumbar plexus

T12-L4

Sacral plexus

L4-S4

Nerve plexuses supplying the lower limb

Lumbar plexus (T12-L4) and sacral plexus (L4-S4)

Femoral nerve

L2-L4

Muscles innervated by the femoral nerve

All anterior thigh muscles, iliacus, and half of pectineus

Structure through which the femoral nerve passes into the thigh

Deep to the inguinal ligament

Obturator nerve

L2-L4

Muscles innervated by the obturator nerve

All medial thigh muscles

Structure through which the obturator nerve enters the thigh

Obturator foramen

Superior gluteal nerve

L4-S1

Muscles innervated by the superior gluteal nerve

Gluteus medius, gluteus minimus, tensor fasciae latae

Inferior gluteal nerve

L5-S2

Muscle innervated by the inferior gluteal nerve

Gluteus maximus

Sciatic nerve

L4-S3

Exit point of the sciatic nerve from the pelvis

Through the greater sciatic foramen, inferior to piriformis

Major nerves into which the sciatic nerve bifurcates

Tibial nerve and common fibular nerve

Tibial nerve

L4-S3

Muscles innervated by the tibial nerve

All posterior thigh muscles (except short head of biceps femoris) and all posterior leg muscles

Nerves into which the tibial nerve branches at the foot

Medial plantar and lateral plantar nerves

Muscles innervated by the medial and lateral plantar nerves

All intrinsic muscles of the plantar foot (medial: abductor hallucis & flexor digitorum brevis; lateral: abductor digiti minimi)

Common fibular nerve

L4-S2

Muscle innervated by the common fibular nerve

Biceps femoris (short head)

Nerves into which the common fibular nerve bifurcates

Superficial fibular nerve and deep fibular nerve

Muscles innervated by the superficial fibular nerve

Fibularis longus and fibularis brevis (lateral leg)

Muscles innervated by the deep fibular nerve

All anterior leg muscles and both dorsal foot muscles

Sensory area supplied by the deep fibular nerve

The "flip-flop" area between the first and second toes

Clinical condition from injury to the common fibular nerve at the fibular neck

Foot drop (loss of dorsiflexion and toe extension, steppage gait)

Definition of a nerve plexus

Intermingling of ventral rami axons from different spinal cord levels, reorganized into peripheral nerves.

Movement lost if the femoral nerve is damaged

Knee extension (quadriceps paralysis)

Cutaneous area supplied by the femoral nerve

Anterior thigh and medial leg (via saphenous branch)

Movement lost if the obturator nerve is damaged

Thigh adduction

Cutaneous area supplied by the obturator nerve

Small area of medial thigh

Gait abnormality from damage to the superior gluteal nerve

Trendelenburg gait (pelvis drops on opposite side during walking)

Movement lost if the inferior gluteal nerve is damaged

Hip extension (gluteus maximus weakness)

Effects of sciatic nerve injury

Weakness/paralysis of hamstrings and all muscles below the knee (depending on location of injury)

Movements lost if the tibial nerve is injured

Plantarflexion and toe flexion

Cutaneous areas supplied by the tibial nerve

Sole of the foot (via medial & lateral plantar nerves)

Vulnerability of the common fibular nerve

Around the neck of the fibula

Movements lost in foot drop

Dorsiflexion and toe extension

Motor functions allowed by the deep fibular nerve

Dorsiflexion of the ankle, extension of toes

Sensory loss with deep fibular nerve injury

Loss of sensation in the web space between 1st and 2nd toes

Movement lost if the superficial fibular nerve is damaged

Eversion of the foot

Cutaneous area supplied by the superficial fibular nerve

Most of the dorsum of the foot