Which muscle is responsible for flexing the elbow?

The muscle responsible for flexing the elbow is primarily the brachialis. This muscle lies underneath the biceps brachii and is the main mover when the elbow is flexed in both pronated and neutral positions. It is specifically designed for flexion at the elbow joint, making it highly effective regardless of the position of the forearm.

While the biceps brachii also assists in elbow flexion, it is more specifically engaged when the forearm is supinated. The triceps brachii is mainly responsible for extending the elbow, and the flexor carpi radialis plays a role in wrist flexion rather than elbow flexion. This underscores the unique function of the brachialis as the primary muscle for elbow flexion.