Which muscles are involved in radial deviation of the wrist (bending toward the thumb)?

Which muscles are involved in radial deviation of the wrist (bending toward the thumb)?

• A. Extensor carpi radialis longus, extensor carpi radialis brevis, abductor pollicis longus, and extensor pollicis brevis
• B. Flexor carpi radialis
• C. Flexor pollicis longus
• D. Extensor carpi ulnaris

Answer: (A)

Radial deviation of the wrist means moving the hand toward the thumb side. The muscles that pull the wrist in that direction are on the radial (thumb) side of the forearm and cross the wrist joint, producing abduction of the hand. The flexor carpi radialis and the extensor carpi radialis longus and brevis are the primary wrist abductors on the radial side; they flexion or extend the wrist while pulling toward the radius. In addition, muscles that act on the thumb and cross the wrist—the abductor pollicis longus and the extensor pollicis brevis—also contribute to radial deviation because their pull lies toward the thumb side, helping to move the wrist in that direction and stabilize it during thumb movements. Together, these muscles create the radial deviation. The other muscles listed either pull the wrist toward the ulnar side or primarily act on the thumb itself without contributing to the wrist moving toward the thumb side.

Radial deviation of the wrist means moving the hand toward the thumb side. The muscles that pull the wrist in that direction are on the radial (thumb) side of the forearm and cross the wrist joint, producing abduction of the hand.

The flexor carpi radialis and the extensor carpi radialis longus and brevis are the primary wrist abductors on the radial side; they flexion or extend the wrist while pulling toward the radius. In addition, muscles that act on the thumb and cross the wrist—the abductor pollicis longus and the extensor pollicis brevis—also contribute to radial deviation because their pull lies toward the thumb side, helping to move the wrist in that direction and stabilize it during thumb movements.

Together, these muscles create the radial deviation. The other muscles listed either pull the wrist toward the ulnar side or primarily act on the thumb itself without contributing to the wrist moving toward the thumb side.