Which muscle flexes and adducts the wrist?

• A. Flexor Carpi Ulnaris
• B. Flexor Carpi Radialis
• C. Palmaris Longus
• D. Extensor Carpi Ulnaris

Answer: (A)

When you bend the wrist and bring the hand toward the pinky side, the muscle that does both actions best is the one on the ulnar side of the forearm. The flexor carpi ulnaris crosses the wrist on that side and, when it contracts, it flexes the wrist and pulls the hand toward the ulna (ulnar deviation). Its tendon attaches to the pisiform and the base of the fifth metacarpal, aligning its pull to produce both flexion and adduction. In contrast, the flexor carpi radialis flexes the wrist and moves the hand toward the thumb side (radial deviation), the palmaris longus mainly tenses the palmar fascia with flexion and has little effect on deviation, and the extensor carpi ulnaris extends the wrist and mainly contributes to ulnar deviation rather than flexion. So the flexor carpi ulnaris is the one that both flexes and adducts the wrist.