Final Answer:
The biceps brachii, the brachialis, and the brachioradialis all contribute to some of the same movements. These muscles would be d) Synergists
Step-by-step explanation:
The biceps brachii, brachialis, and brachioradialis are synergists. Synergistic muscles work together to perform a specific movement or action. In this case, these muscles assist in elbow flexion, where they collaborate to execute the bending of the forearm at the elbow joint.
Synergists are muscles that complement the action of the prime mover or agonist muscles. While the prime mover primarily performs a specific movement, synergistic muscles aid in refining the action, providing additional support, stability, or control to ensure smooth and coordinated motion.
The biceps brachii is a prime mover for elbow flexion but requires support from synergistic muscles like the brachialis and brachioradialis to optimize the movement. These synergistic muscles assist the biceps brachii in executing elbow flexion but don't act as the primary muscle initiating the movement.
Therefore, option D is the right answer.