Collateral interphalangeal ligaments of hand

At a glance

English

Collateral interphalangeal ligaments of hand

Latin (TA2)

Ligamenta interphalangea collateralia manus

System

Ligament

Region

Hand

Side

Paired, left and right

About the collateral interphalangeal ligaments of hand

The collateral interphalangeal ligaments are the side ligaments of the hinge joints of the fingers and thumb. Each finger has a proximal and a distal interphalangeal joint, and the thumb has a single one; every joint carries a radial and an ulnar collateral ligament. Each band is a strong cord that runs obliquely across the side of the joint. Its proximal end is set towards the back, in a small pit on the side of the head of the more proximal phalanx, and its distal end sits further forward, on the palmar part of the side of the base of the next phalanx.

Along each side, the main band is accompanied by a thinner fan, the accessory collateral ligament, which runs further forwards to the edges of the palmar plate on the front of the joint. Together the palmar plate and the two collateral ligaments form a three-sided box. The joint is therefore enclosed below and on both sides, with the extensor expansion covering it from behind.

Because the heads of the phalanges are pulley-shaped and the collateral ligaments are fixed close to the axis of movement, they are fairly tight through most of the range of bending and straightening. They prevent the finger from bending sideways or twisting at the joint, so that flexion and extension take place cleanly in one plane. The palmar plate stops the joint from bending backwards.

A sideways blow to a finger, common in ball sports, can sprain or tear one of these ligaments, most often the radial collateral of the proximal joint. The joint becomes swollen and painful and may feel unstable when stressed to the side. If the joint is splinted straight for a long time, the ligaments can shorten and leave it stiff, so the position of splinting matters.

Attachments and function

Attaches from

A small pit on each side of the head of the more proximal phalanx, towards its dorsal side.

Attaches to

The palmar part of the side of the base of the more distal phalanx; the accessory part reaches the palmar plate.

Function

Prevent sideways bending and rotation at the finger and thumb hinge joints, so that the joints move only in flexion and extension.

Nerve supply

Articular branches of the palmar and dorsal digital nerves.

Blood supply

Branches of the palmar digital arteries.