The |pectoralis major| muscle is located at the front of the thoracic cage. It is a thick, fan-shaped muscle and is divided into two parts that begin at the armpit and cover most of the front of the chest. The upper, or clavicular, part is attached to the clavical (collar bone). The lower, or sternocostal, is attached mainly to the |sternum| (breast bone) and |costal cartilage|. This muscle is used when you bring your arms across the chest, raise and lower the arms and to rotate the arms. The clavicular portion will raise the arm, while the sternocostal portion will pull it down.
