What is the prime mover (agonist) for elbow flexion?

The prime mover, or agonist, for elbow flexion is primarily the biceps brachii. This muscle is responsible for the majority of the force exerted during this movement, allowing the elbow to bend. The biceps brachii engages and contracts to pull the forearm towards the shoulder, facilitating flexion at the elbow joint.

While the brachialis also contributes to elbow flexion, particularly with greater force during certain activities or positions, it is the biceps brachii that is more commonly recognized as the main muscle engaged in this action. The triceps brachii, on the other hand, acts as the antagonist by extending the elbow, and the rhomboideus is associated with scapular movements rather than actions at the elbow joint. Therefore, understanding the roles of these muscles helps clarify the mechanics of elbow flexion, highlighting the biceps brachii as the prime mover in this particular motion.