What is the primary function of the biceps brachii?

The primary function of the biceps brachii is elbow flexion. This muscle is located in the upper arm and plays a significant role in bending the elbow joint. When the biceps brachii contracts, it pulls the forearm closer to the upper arm, effectively flexing the elbow. This action is crucial in various movements, including lifting items, performing curls, and other activities that require bending the arm.

While the biceps brachii can assist in other actions, such as shoulder flexion due to its anatomical position, its most direct and primary role remains elbow flexion. Other options refer to functions primarily associated with different muscles in the upper arm and shoulder region, which do not align with the key function of the biceps brachii.