The wrist extensors are a group of nine individual muscles on the back of the forearm that act on the wrist and fingers and help carry out complex movements of the hands such as wrist extension, or moving the top of the hands backward toward the wrists. (fitnessandpower.com)
Sit on a flat bench and hold a barbell in both hands over the end of the bench with the backs of your forearms flat down. (fitnessandpower.com)
Just think the muscles on the front of the forearm bend the wrist and fingers, and the muscles on the back of the forearm straighten the wrist and fingers. (all-about-arm-exercises.com)