Which muscle extends the fingers and wrist?

• A. Extensor Digitorum
• B. Extensor Carpi Ulnaris
• C. Flexor Digitorum Superficialis
• D. Flexor Pollicis Longus

Answer: (A)

Extending the fingers and the wrist is done by a muscle that runs along the back of the forearm and sends tendons to the fingers. Extensor Digitorum is the primary finger extensor, attaching to the extensor expansions of the index through little fingers. This arrangement allows it to straighten the metacarpophalangeal joints and assist with extending the finger joints, while its tendon crossing the wrist means it also contributes to lifting the hand at the wrist. The other muscles listed don’t accomplish both actions: Extensor Carpi Ulnaris mainly extends the wrist and can adduct the hand; Flexor Digitorum Superficialis flexes the fingers; Flexor Pollicis Longus flexes the thumb and tends toward wrist flexion rather than extension.