The pectoralis major is a large, fan-shaped muscle located in the upper chest. It plays a crucial role in the movement of the shoulder joint, allowing for actions such as pushing, lifting, and rotating the arm. This muscle is divided into two parts: the clavicular head, which originates from the collarbone, and the sternal head, which originates from the sternum. In addition to its functional importance, the pectoralis major is also significant in physical appearance, contributing to the overall shape and definition of the chest. Strengthening this muscle is common in fitness routines, often targeted through exercises like bench presses and push-ups.