Which muscle is characterized by having three bellies?

The triceps brachii is characterized by having three distinct muscle bellies, which is reflected in its name. The term "triceps" literally means "three heads," and in this muscle, there are three origins: the long head, the lateral head, and the medial head. Each of these heads contributes to the muscle's overall function of extending the elbow joint, allowing for movements like pushing and straightening the arm.

The muscle’s structure is significant because it allows for greater force production due to the combined action of the three heads during contraction. Understanding this anatomical feature is essential for comprehending how the muscle operates in various movements and activities. The other muscles mentioned do not have three distinct bellies; they may have different functions and origins, but only the triceps brachii is specifically identified by its three-headed structure.