Collateral metatarsophalangeal ligaments

At a glance

English

Collateral metatarsophalangeal ligaments

Latin (TA2)

Ligamenta metatarsophalangea collateralia

System

Ligament

Region

Foot

Side

Paired, left and right

About the collateral metatarsophalangeal ligaments

The metatarsophalangeal joints are the knuckles of the foot, where the rounded head of each metatarsal fits into a shallow socket on the base of the first phalanx of a toe. They are ellipsoid joints that allow the toes to bend up and down and, to a small extent, to spread apart and come together. Each joint is surrounded by a thin capsule strengthened by a plantar ligament underneath and by a collateral ligament on each side.

The collateral ligaments are strong, rounded cords. Each starts from a small tubercle at the edge of the metatarsal head, set towards its upper and back part, and with a depression in front of it. It runs forwards and downwards to the side of the base of the proximal phalanx. A deeper fan of fibres, the accessory collateral ligament, spreads to the edges of the plantar ligament. Because the attachment on the metatarsal sits above the centre of the head, the ligaments are slack when the toe is straight and tighten as it bends down.

On the top of the joint there is no separate dorsal ligament; the long and short extensor tendons and their expansion lie directly on the capsule and do that job. The deep transverse metatarsal ligament joins the plantar ligaments of neighbouring joints.

The collateral ligaments keep the toe in line with its metatarsal and prevent it being pushed sideways. In hallux valgus the medial ligament and capsule of the big toe joint are gradually stretched as the toe drifts outwards. Forceful bending of the big toe upwards, common in field sports, can tear the plantar plate and collateral ligaments together, the injury called turf toe.

Attachments and function

Attaches from

The tubercle and depression on the side of each metatarsal head.

Attaches to

The side of the base of the corresponding proximal phalanx and the margin of the plantar ligament.

Function

Stabilise the metatarsophalangeal joints against sideways force, especially when the toes are flexed, while allowing flexion, extension and a little spreading.

Nerve supply

Branches of the medial and lateral plantar nerves, with dorsal branches from the deep and superficial fibular nerves.

Blood supply

The plantar and dorsal metatarsal arteries and their digital branches.