Which muscle extends and abduc ts the wrist?

Which muscle extends and abduc ts the wrist?

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

Answer: (A)

Extending and abducting the wrist means lifting the back of the hand while moving it toward the thumb side (radial deviation). The Extensor Carpi Radialis Longus does both: it extends the wrist and pulls it toward the radial (thumb) side when it contracts. The other muscles either don’t extend and abduct together, or they abduct only without extending, or they extend but move the wrist toward the pinky side (ulnar deviation) or primarily focus on finger extension. For example, the Extensor Carpi Ulnaris extends the wrist but adducts (ulnar deviation), the Extensor Digitorum mainly extends the fingers and assists with wrist extension without producing radial deviation, and the Flexor Carpi Radialis flexes the wrist and abducts (radial deviation) but does not extend. So the one that both extends and abducts is the Extensor Carpi Radialis Longus.

Extending and abducting the wrist means lifting the back of the hand while moving it toward the thumb side (radial deviation). The Extensor Carpi Radialis Longus does both: it extends the wrist and pulls it toward the radial (thumb) side when it contracts. The other muscles either don’t extend and abduct together, or they abduct only without extending, or they extend but move the wrist toward the pinky side (ulnar deviation) or primarily focus on finger extension. For example, the Extensor Carpi Ulnaris extends the wrist but adducts (ulnar deviation), the Extensor Digitorum mainly extends the fingers and assists with wrist extension without producing radial deviation, and the Flexor Carpi Radialis flexes the wrist and abducts (radial deviation) but does not extend. So the one that both extends and abducts is the Extensor Carpi Radialis Longus.