Extensor carpi ulnaris
On the ulnar side of the forearm lies the extensor carpi ulnaris muscle. This muscle allows the wrist, or carpus, to extend and bend. It begins on the outer side of the elbow on the lateral epicondyle of the humerus and crosses the forearm downward. It inserts at the base of the ‘pinky finger’, or the fifth metacarpal. The muscle is supplied with blood by the ulnar artery and innervated by the deep branch of the radial nerve. The extensor carpi ulnaris muscle works in conjunction with the flexor carpi ulnaris muscle during the adduction of the wrist, meaning when the wrist bends toward the body’s midline. However, the extensor carpi ulnaris muscle is the only muscle responsible for ulnar deviation. This refers to the movement of the hand sideways in the direction of the pinky. The extensor carpi ulnaris muscle is the primary muscle used when accelerating a motorcycle. It is often affected by tendonitis and tennis elbow. This muscle can be strengthened with a resistance band. A common exercise is to hold one end of the band in the hand, resting it on the thigh, and placing the other end under the foot. The wrist is then pulled back and slowly returned to its starting position.