The lumbrical muscles of the hand are delicate skeletal muscles on the palmar aspect of the metacarpal bones. There are four of these slender muscles in each hand.
Origin
The lumbrical muscles of the hand originate from the tendons of the flexor digitorum profundus muscle.
Insertion
The short tendons of the muscles each run toward the radial aspect of the corresponding finger and insert at the level of the metacarpophalangeal joint into the extensor expansions of the 2nd–5th fingers.
Innervation
The 1st and 2nd lumbrical muscles are supplied by the median nerve, whereas the deep branch of the ulnar nerve innervates the 3rd and 4th lumbrical muscles. The innervation of the muscles may vary.
Function
The lumbrical muscles of the hand produce flexion at the metacarpophalangeal joints of the fingers and extension at the proximal and distal interphalangeal joints.