Lateral plantar nerve

At a glance

English

Lateral plantar nerve

Latin (TA2)

Nervus plantaris lateralis

System

Nerve

Region

Lower limb

Side

Paired, left and right

About the lateral plantar nerve

The lateral plantar nerve is one of the two branches into which the tibial nerve divides under the flexor retinaculum behind the medial malleolus. Though smaller than the medial plantar nerve, it supplies far more muscles, and its pattern in the foot mirrors the ulnar nerve's pattern in the hand: most of the small deep muscles, and the skin of the lateral one and a half digits.

From its origin it runs obliquely forwards and laterally across the sole with the lateral plantar artery, passing deep to abductor hallucis and then between flexor digitorum brevis below and quadratus plantae above. On reaching the outer border of the foot, in the interval between flexor digitorum brevis and abductor digiti minimi near the base of the fifth metatarsal, it splits into superficial and deep branches. Before dividing, its trunk supplies abductor digiti minimi and quadratus plantae and gives cutaneous twigs to the lateral sole.

The superficial branch splits into a proper digital nerve for the lateral side of the little toe, which also supplies flexor digiti minimi brevis and the interossei of the fourth space, and a common digital nerve for the facing sides of the fourth and fifth toes, which links with the medial plantar nerve. The deep branch curves medially with the lateral plantar artery's deep arch, deep to the long flexor tendons and adductor hallucis, and supplies the second to fourth lumbricals, adductor hallucis and the remaining interossei.

Because it controls the interossei and adductor hallucis, damage weakens the fine adjustments of the toes that keep the foot stable in standing and push-off, and can contribute to clawing. The first branch of the nerve, to abductor digiti minimi, can be trapped between abductor hallucis and quadratus plantae and is a recognised cause of chronic heel pain (Baxter's nerve). It is also compressed with the tibial nerve in tarsal tunnel syndrome, and it is blocked behind the medial malleolus in an ankle block.

Course and supply

Arises from

The tibial nerve, dividing beneath the flexor retinaculum behind the medial malleolus.

Ends in

Divides near the base of the fifth metatarsal into a superficial branch, ending in digital nerves to the lateral one and a half toes, and a deep branch ending in the deep muscles of the sole.

Supplies

Motor to quadratus plantae, abductor and flexor digiti minimi, adductor hallucis, all interossei and the lateral three lumbricals; sensory to the lateral sole and the lateral one and a half toes.