What Are the Functions of the Biceps?

Man flexing muscles, focus on hand

Of all the muscles in your body, the biceps are probably the most well known. Ask even a child to show you their muscles and, chances are, they will flex their arms. As well as having aesthetic appeal, the biceps are important muscles that are involved in numerous everyday activities.

The full name of your biceps is biceps brachii. This helps to differentiate it from the other biceps muscle, the biceps femoris, which is part of the hamstrings. Biceps brachii is located on the front of your upper arm and consists of two heads with two different proximal attachment points, called origins, and a single distal insertion point. It crosses two joints and is therefore described as being biaxial.

Function at the Shoulder

Because your biceps brachii crosses your shoulder joint, it is involved any time you raise your arm, a movement called shoulder flexion. The main muscles responsible for this action are your deltoids, or shoulder muscles, but your biceps act as assistance muscles. If you place one hand on your biceps and raise your arm forward, you will feel the tension in your biceps change, which indicates its involvement in this movement. The biceps are only weak shoulder flexors but are, nonetheless, involved in this movement.

Function at the Elbow

The most well known and common function of the biceps is bending your arm; properly called elbow flexion. The biceps do not work alone is this movement, but they are considered to be the primary muscle responsible for this action. The other arm flexors are the brachialis, brachioradialis and pronator teres. To work their biceps, most exercisers perform elbow flexion exercises such as barbell or dumbbell curls.

Function at the Forearm

Your forearm is made up of two bones, the radius and ulna. These bones form an articulation called the radioulnar joint. Your biceps brachii, along with your other supinator muscles, rotate your forearm so your palm is turned upward in a movement called supination. An easy way to remember the term supination is to associate it with facing the sun, because your palms are turned up to the sky when supinated. This action is important when performing tasks such as screwing in a light bulb or undoing the lid on a jar.