The TuneUp Program

Muscles that articulate the wrist

The muscles that articulate the wrist can be broadly grouped according to their action. The flexors originate on the medial epicondyle of the humerus, traverse the inside of the forearm and connect on the carpals of the wrist, the metacarpals of the hand or the phalanges of the fingers and thumb. The extensors originate on the lateral epicondyle of the humerus, run down the back of the forearm and again attach on the carpals, metacarpals or phalanges.

So while the flexors flex and the extensors extend these aren't the only movements available at the wrist. Lateral deviation toward the ulna (the little finger) is possible when both flexor and extensor on the ulnar side (flexor carpi ulnaris and extensor carpi ulnaris) contract together. Lateral deviation toward the radius involves both flexor and extensor on the radial side although extensor carpi radialis muscles do most of the work. Two muscles that control the thumb: abductor pollicis longus and extensor pollicis brevis are also active in radial deviation of the wrist but to a lesser degree.

The wrist muscles also act to stabilise the wrist when the hand is moving or grasping objects. Because the finger flexors for example cross the wrist their contraction should cause the wrist to flex as well. The reason that this doesn't automatically happen is that wrist extensors produce a force in the opposite direction cancelling out any movement of the wrist. This has implications for our playing given the amount of movement that the fingers have to do.