Lumbricals of hand

The lumbrical muscles are four short, intrinsic muscles of the hand that lie in its central compartment. Along with the palmar and dorsal interossei, these muscles belong to the middle muscles of the hand. They have a thin, cylindrical appearance. In fact, they have a worm-like shape, which is why they were given this name (the name comes from the Latin word lumbricus, meaning “earthworm”). These muscles are unique in that they originate from the tendons of the flexor digitorum profundus and insert into the extensor expansions of the extensor digitorum muscle.