Lumbricals of the hand

Musculi lumbricales manus

MuscularDeep musclesArmLeft and right

View left in 3D View right in 3D

What it is

Four slender worm-like muscles arising from the flexor digitorum profundus tendons in the palm and inserting on the radial (thumb) side of the extensor expansions of the fingers.

Function

Flex the knuckles while straightening the finger joints (the "tabletop" position).

Size

Each 4–6 cm long and a few mm thick.

Clinical note

Unique in arising from tendons; the two lateral ones are supplied by the median nerve, the two medial ones by the ulnar nerve.