The lumbricals are four small muscles in each hand and four in each foot. In the hand, they sit deep in the palm, starting from the tendons of the main finger-bending muscle and running to the back of the fingers. Their job is a bit unusual because they help you do two actions at once: they help bend the big knuckles where the fingers meet the hand, while also helping straighten the middle and end finger joints. That combination is essential for precise finger control, like typing, gripping a barbell smoothly, holding a dumbbell without your fingers “clawing,” and keeping your wrist and fingers aligned during pull-ups, rows, and deadlifts.
