What term describes a muscle that assists another muscle in performing an action?

The term that describes a muscle that assists another muscle in performing an action is "synergist." Synergist muscles work in conjunction with agonist muscles, which are the primary movers responsible for the main action. For example, when performing a bicep curl, the biceps brachii act as the agonist, while the brachialis and brachioradialis serve as synergists to help facilitate the motion. By contracting alongside the agonist, synergists provide additional force and support, helping to stabilize the movement and enhance overall efficiency.

In contrast, an agonist is the primary muscle that produces a specific movement, while an antagonist serves to oppose or counteract the action of the agonist, allowing for controlled movement and balance. Stabilizers are muscles that help maintain posture or stabilize the body during movement, but they do not directly assist in the action of another muscle. Understanding these roles is crucial for comprehending muscle dynamics during physical activities and exercises.