Lumbrical muscles of the hand

Last revised by Dr Daniel J Bell on 21 Aug 2019

The lumbrical muscles of the hand are intrinsic muscles of the hand associated with the flexor digitorum profundus (FDP) tendon.

The four lumbricals arise from the tendons of the flexor digitorum profundus (FDP). The first and second lumbricals arise from the radial side of the FDP tendons of the index and middle fingers. The third lumbrical arises from the adjacent tendons of the middle and ring finger while the fourth arises from the adjacent tendons of the ring and little finger.

Each lumbrical travels on the radial side of its corresponding finger and attaches to the lateral edge of the extensor expansion complex on the dorsum of each finger.

Variation in the muscles bellies and attachments of the lumbricals are common with any being possibly unipennate or bipennate. Accessory lumbrical slips have been described as also attaching to the tendons of the flexor digitorum superficialis.

The name comes from the Latin 'lumbricus' meaning 'worm' 5 describing the gross appearance of the muscle.

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Cases and figures

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