In muscle actions, which term describes a muscle that opposes or reverses the movement produced by the prime mover (agonist)?

• A. Synergist
• B. Prime mover (agonist)
• C. Antagonist
• D. Fixator

Answer: (C)

Verified step by step guidance

1. Understand the role of the prime mover (agonist): it is the muscle primarily responsible for producing a specific movement at a joint.
2. Identify the muscle that opposes or reverses the action of the prime mover; this muscle works against the movement to provide control and balance.
3. Recall the terminology: the muscle that opposes the prime mover is called the 'antagonist'.
4. Differentiate from other terms: a 'synergist' assists the prime mover, and a 'fixator' stabilizes the origin of the prime mover.
5. Conclude that the correct term for the muscle opposing the prime mover is 'antagonist'.