In Plain English
The mid chest is the central portion of your chest, spanning from the sternum to the upper arm. It’s part of the larger pectoralis major and helps bring your arm across your body and inward while contributing most of the overall thickness and width of the chest.
Technical Definition
The mid chest refers to the sternocostal head of the pectoralis major, originating primarily from the sternum and upper costal cartilages and inserting onto the lateral lip of the intertubercular groove of the humerus. Its fiber orientation gives it a strong mechanical advantage during shoulder horizontal adduction, shoulder adduction, and shoulder internal rotation.




















