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 is carried out by the extensor muscles on the back of the forearm, with the primary finger extensor being the extensor digitorum. Its tendons reach the fingers and spread to extend the metacarpophalangeal joints (and assist the finger joints further). Because this muscle crosses the wrist, it can also contribute to wrist extension when it contracts. The other options are more specialized: extending the wrist alone is mainly done by the extensor carpi ulnaris (and related extensors), flexor digitorum superficialis flexes the fingers rather than extends them, and flexor pollicis longus flexes the thumb. So the muscle that best fits extending both the fingers and the wrist is extensor digitorum.