What are the different types of muscles?

• A. Skeletal, Cardiac, Smooth
• B. Prime Mover
• C. Synergist
• D. Prime Mover, Synergist, Antagonist

Answer: (D)

Muscles can be understood by the role they play in a movement. The primary driver of a movement is the prime mover (agonist), the muscle that generates the main force to produce the action. Nearby or assisting muscles are called synergists; they help by adding extra force, controlling the movement, and stabilizing the joint so the action is smooth. The muscle that opposes the prime mover is the antagonist; it provides a braking action that slows or reverses the movement and helps control the motion.

For example, during elbow flexion, the biceps brachii typically acts as the prime mover, the brachialis and other nearby muscles serve as synergists to enhance flexion, and the triceps brachii acts as the antagonist to oppose the bending action. Keep in mind that a single muscle can switch roles depending on the movement and the joint being acted upon, but these three categories capture the common functional roles muscles assume during actions.