The primary functions of the biceps brachii muscle at the elbow joint are to flex the forearm (bend the elbow) and supinate the forearm (rotate the palm upwards).
Detailed Explanation of Biceps Function at the Elbow
The biceps brachii, often simply referred to as the biceps, is a two-headed muscle located on the front of the upper arm. Its tendons attach to the radius bone in the forearm, crossing the elbow joint. This positioning allows the biceps to perform several key movements at the elbow:
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Flexion: The biceps is a powerful flexor of the forearm. This means it contracts to decrease the angle between the upper arm and the forearm, effectively bending the elbow. Think of lifting a weight or bringing your hand to your shoulder.
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Supination: The biceps is also a strong supinator of the forearm. Supination is the action of rotating the forearm so that the palm faces forward or upwards. This is the motion you use when turning a doorknob counter-clockwise or holding a bowl of soup. The biceps' supination strength is most pronounced when the elbow is flexed.
Importance of Supination
While other muscles contribute to elbow flexion (like the brachialis), the biceps is unique in its ability to strongly supinate the forearm. This supination function is crucial for many everyday activities.
Biceps Support at the Shoulder
It's also worth noting, as the provided reference points out, that the biceps also plays a role in stabilizing the shoulder joint, helping to keep the humeral head (top of the arm bone) properly positioned within the joint. While this isn't a function at the elbow, it is a function of the biceps.
