Which muscle flexes the wrist?

Which muscle flexes the wrist?

• A. Palmaris longus
• B. Flexor carpi radialis
• C. Extensor carpi radialis longus
• D. Flexor digitorum superficialis

Answer: (A)

Wrist flexion comes from muscles that cross the wrist on the anterior (palm) side and shorten to bring the palm toward the forearm. The palmaris longus fits this role nicely: its tendon travels across the wrist and attaches to the palmar aponeurosis, so when it contracts it tightens the palm and helps bend the hand at the wrist. While other muscles in the mix can flex the wrist as well, the palmaris longus is the classic, straightforward example of a wrist flexor. The extensor carpi radialis longus acts on the opposite side and extends the wrist, not flexes it. The flexor digitorum superficialis mainly flexes the fingers (with only a secondary, less prominent contribution to wrist flexion), and the flexor carpi radialis does flex the wrist but also deviates the hand toward the thumb side. In this context, the palmaris longus best represents a wrist-flexing muscle.

Wrist flexion comes from muscles that cross the wrist on the anterior (palm) side and shorten to bring the palm toward the forearm. The palmaris longus fits this role nicely: its tendon travels across the wrist and attaches to the palmar aponeurosis, so when it contracts it tightens the palm and helps bend the hand at the wrist. While other muscles in the mix can flex the wrist as well, the palmaris longus is the classic, straightforward example of a wrist flexor. The extensor carpi radialis longus acts on the opposite side and extends the wrist, not flexes it. The flexor digitorum superficialis mainly flexes the fingers (with only a secondary, less prominent contribution to wrist flexion), and the flexor carpi radialis does flex the wrist but also deviates the hand toward the thumb side. In this context, the palmaris longus best represents a wrist-flexing muscle.