Medial plantar nerve

At a glance

English

Medial plantar nerve

Latin (TA2)

Nervus plantaris medialis

System

Nerve

Region

Lower limb

Side

Paired, left and right

About the medial plantar nerve

Beneath the flexor retinaculum, behind the medial malleolus, the tibial nerve ends by splitting into the medial and lateral plantar nerves. Of the two, the medial plantar nerve is the bigger, and it travels with the medial plantar artery, which lies on its inner side. Its layout in the sole closely mirrors the median nerve's layout in the palm: a few muscles on the great-toe side, and skin of the medial three and a half digits.

From its origin the nerve runs forwards deep to abductor hallucis, then surfaces in the groove between that muscle and flexor digitorum brevis. Near the bases of the metatarsals it gives off a proper digital nerve for the great toe's inner border and then breaks into three common plantar digital nerves. These pass forwards between the aponeurosis's digital slips, each then dividing in two: the first for the facing sides of toes one and two, the second for toes two and three, and the third for toes three and four. The third common nerve receives a communicating twig from the lateral plantar nerve.

Its motor branches reach flexor digitorum brevis and abductor hallucis, entering their deep surfaces close to where the nerve begins; flexor hallucis brevis, via the great toe's inner digital nerve; and the first lumbrical, via the first common digital nerve. Skin branches come through the plantar aponeurosis in the gap between abductor hallucis and the short toe flexor to supply the inner sole, and joint twigs go to the tarsal and metatarsal joints. Each proper digital nerve sends a dorsal branch near the tip of its toe to the nail bed and ends in the pulp.

The nerve can be compressed with the tibial nerve in the tarsal tunnel, or on its own where it passes under abductor hallucis near the navicular, which is sometimes called jogger's foot and causes burning pain along the medial arch and into the inner toes. A Morton's neuroma, a thickening of a common digital nerve, most often affects the branch to the third web space, where medial and lateral plantar fibres meet. Anaesthetists can block the nerve behind the medial malleolus as part of an ankle block.

Course and supply

Arises from

The tibial nerve, dividing under the flexor retinaculum near the origin of abductor hallucis.

Ends in

One proper digital nerve for the great toe's inner border and three common plantar digital nerves whose proper digital nerves reach toes one to four.

Supplies

Motor to abductor hallucis, flexor digitorum brevis, flexor hallucis brevis and lumbrical one; sensory to the inner sole and the plantar skin and nail beds of the medial three and a half toes.