Palmar interphalangeal ligaments

At a glance

English

Palmar interphalangeal ligaments

Latin (TA2)

Ligamenta interphalangea palmaria

System

Ligament

Region

Hand

Side

Paired, left and right

About the palmar interphalangeal ligaments

The palmar interphalangeal ligaments, usually called palmar or volar plates, form the front wall of each interphalangeal joint of the hand. Each is a thick fibrocartilaginous pad lying between the head of one phalanx and the base of the next. It is firmly fixed to the base of the more distal phalanx, while its proximal part is thinner and more pliable. At the proximal interphalangeal joint the proximal edge is anchored on each side to the shaft of the proximal phalanx by two narrow bands, the check-rein ligaments, which leave the centre of the edge free.

On each side the plate is joined by the collateral ligament and by the accessory collateral ligament, which runs from the proximal phalanx down to the plate and the side of the middle phalanx base. The plate forms the floor and the collaterals the walls of a mobile box that travels with the distal bone and keeps the joint stable through its whole range. On its palmar face lie the flexor tendons in their fibrous sheath. The sheath is fixed firmly to the shafts of the phalanges by the A2 and A4 annular pulleys, but at the proximal joint the A3 pulley and part of the first cruciform pulley attach it to the movable palmar plate instead. When the finger bends, the flexible proximal edge of the plate folds into a recess just behind the head of the proximal phalanx.

The plates prevent hyperextension; the check-rein ligaments make extension at the proximal joint especially limited. Because the plate lies close to the insertion of flexor digitorum superficialis and holds the tendons away from the joint, it also increases their leverage.

Forcing a finger backwards, as when it is struck by a ball, can tear the plate or pull off a small flake of bone from the middle phalanx base. This palmar plate injury needs early guided movement to avoid a stiff, bent joint.

Attachments and function

Attaches from

The neck and shaft of the more proximal phalanx, through a thin, flexible edge; at the proximal joint through the check-rein ligaments.

Attaches to

The palmar margin of the base of the more distal phalanx.

Function

Form the front wall of the finger joints, prevent hyperextension, carry the flexor tendon sheath and improve the leverage of the flexor tendons.

Nerve supply

Articular branches of the palmar digital nerves.

Blood supply

Branches of the palmar digital arteries.