Which muscle is primarily responsible for flexing the elbow?

The biceps brachii is the primary muscle responsible for flexing the elbow due to its anatomical position and function. When the biceps contract, they pull the forearm towards the shoulder, decreasing the angle at the elbow joint. This flexion is facilitated by the biceps’ two heads (the long head and the short head), which originate from different points at the shoulder and insert on the radius in the forearm.

While other muscles are involved in elbow movement, the biceps is the most prominent and effective for this specific action of flexion. The triceps, on the other hand, serve as the primary extensor of the elbow, aiding in straightening the arm. The deltoids are primarily responsible for shoulder movements, and the forearm flexors assist with wrist flexion but do not play a direct role in elbow flexion. This makes the biceps the correct choice for the question regarding flexing the elbow.