Which term describes the prime mover, the muscle that shortens to create movement?

Which term describes the prime mover, the muscle that shortens to create movement?

• A. Antagonist
• B. Agonist
• C. Synergist
• D. Isometric

Answer: (B)

The term describes the muscle that shortens to create movement is the agonist. This muscle is the primary conductor of the action, often called the prime mover, because its concentric shortening provides the main force driving the joint through its range of motion. For example, during elbow flexion, the biceps brachii contracts and shortens, acting as the agonist that produces the movement. The opposing muscle, which lengthens to allow that motion, is the antagonist. Other muscles around the joint can assist or stabilize; these are synergists. And if a muscle contracts without changing length, that’s an isometric contraction.

The term describes the muscle that shortens to create movement is the agonist. This muscle is the primary conductor of the action, often called the prime mover, because its concentric shortening provides the main force driving the joint through its range of motion. For example, during elbow flexion, the biceps brachii contracts and shortens, acting as the agonist that produces the movement. The opposing muscle, which lengthens to allow that motion, is the antagonist. Other muscles around the joint can assist or stabilize; these are synergists. And if a muscle contracts without changing length, that’s an isometric contraction.