In Plain English
The chest is the broad muscle group covering the front of your upper torso, extending from the collarbone, sternum, and ribs to the upper arm. It consists primarily of the pectoralis major and helps move your arm forward, across your body, downward, and inward while giving the chest its size, shape, and thickness.
Technical Definition
The chest refers primarily to the pectoralis major, a large fan-shaped muscle composed of clavicular and sternocostal fibers. It originates from the medial clavicle, sternum, costal cartilages, and external oblique aponeurosis before inserting onto the lateral lip of the intertubercular groove of the humerus. Its fiber orientation enables shoulder flexion, shoulder adduction, shoulder internal rotation, and horizontal adduction, with different regions contributing more strongly depending on arm position and movement direction.





















