What is the name of the muscle that produces a movement as compared with the muscle that produces an opposite movement?

The muscle that produces a movement is called the "agonist," while the muscle that produces the opposite movement is known as the "antagonist." For example, during elbow flexion, the biceps brachii acts as the agonist, while the triceps brachii serves as the antagonist. This relationship allows for coordinated movement and control in the body.