Final answer:
The extensor digitorum is the muscle responsible for extending the wrist and digits in humans. It contrasts with flexor muscles that flex the fingers, and it plays a crucial role in hand dexterity and fine motor skills.
Step-by-step explanation:
The muscle that extends the wrist and digits in a human is the extensor digitorum. This muscle is responsible for extending the hand at the wrist as well as the phalanges, which are the bones in the fingers. The extensor digitorum works in concert with other muscles such as the extensor carpi radialis brevis, which also extends and abducts the hand at the wrist, and the extensor carpi ulnaris, which extends and adducts the hand at the wrist.
These muscles contrast with the flexor muscles such as the flexor digitorum superficialis and flexor digitorum profundus, which flex the fingers and the hand. When the extensor digitorum contracts, it increases the angle at the joints, allowing the fingers to straighten out from a flexed position. This action is essential for daily activities that require fine motor skills and hand dexterity.