상완근, or the biceps brachii, is a prominent muscle located in the upper arm. It plays a crucial role in the movement of the elbow and shoulder joints, allowing for actions such as bending the arm and lifting objects. The muscle has two heads, the long head and the short head, which contribute to its shape and function. This muscle is often targeted in strength training exercises, such as bicep curls and pull-ups, to enhance arm strength and appearance. Proper training and stretching of the 상완근 can improve overall arm functionality and reduce the risk of injury during physical activities.