What is the term for the primary muscle responsible for causing a movement?

The term for the primary muscle responsible for causing a movement is known as the agonist. Agonists are the muscles that contract to produce specific movements, making them crucial in any action or activity that involves muscle use. For instance, when performing a bicep curl, the biceps brachii acts as the agonist because it is the muscle primarily responsible for flexing the elbow.

Understanding the role of the agonist is important in sports medicine, as it helps in designing effective training and rehabilitation programs by identifying which muscles should be targeted for strengthening or conditioning. The agonist's function is complemented by other types of muscles such as antagonists, synergists, and stabilizers, but the agonist is distinctly recognized as the primary mover in a given action.