In muscle actions, what is the primary function of a synergist muscle during a movement?

• A. It provides the main force responsible for producing the movement
• B. It directly opposes the agonist to slow or stop the movement
• C. It maintains posture by contracting continuously without producing joint movement
• D. It assists the agonist by adding force and/or reducing undesirable movements at a joint

Answer: (D)

Verified step by step guidance

1. Step 1: Understand the roles of different muscle types during movement. The agonist (or prime mover) is the muscle primarily responsible for generating a specific movement.
2. Step 2: Define the synergist muscle. A synergist assists the agonist by either adding extra force to the movement or by stabilizing the joint to prevent unwanted motions.
3. Step 3: Differentiate the synergist from other muscle types: the antagonist opposes the agonist to slow or stop movement, and fixators stabilize the origin of the agonist to enhance its effectiveness.
4. Step 4: Recognize that the synergist does not produce the main force but supports the agonist, making the movement smoother and more efficient.
5. Step 5: Conclude that the primary function of a synergist muscle during movement is to assist the agonist by adding force and/or reducing undesirable movements at a joint.