What is the primary function of the biceps?

The primary function of the biceps brachii is to flex the elbow. This muscle is located in the upper arm and comprises two heads (the long head and the short head), which originate from different parts of the shoulder blade and converge to insert at the radius bone of the forearm. When the biceps contracts, it pulls on the radius, resulting in the bending of the elbow joint, which allows for movements such as bringing the forearm up toward the shoulder.

In addition to its role in elbow flexion, the biceps also assists in forearm supination (rotating the palm upward) and can help with shoulder flexion, but its most notable and primary action is flexing the elbow. Understanding this muscle's function is fundamental for exercises targeting the arm and for injury prevention or rehabilitation involving the upper limb.