The pectoralis major is often referred to simply as the pectorals or “pecs”, and is made up of two muscle heads; the clavicular and sternal head. The clavicular head is located to the upper region of the chest, spanning from the clavicle (collarbone) to the humerus (upper arm bone). The sternal head composes the middle and lower chest region.
Due to the clavicular muscle head originating from the clavicle, unlike the sternal head which originates from the sternum, it is possible to actively engage the head while the neighbouring sternal head remains muted. This fact is in contrast to the common myth, often regurgitated on online forums, which states it is impossible to target the upper or lower region of the chest.
Common chest exercises, such as the bench press and chest fly, which involve the transverse flexion of the shoulder joint, will effectively target the clavicular and sternal heads. The clavicular head is also targeted with the abduction and flexion of the shoulder, so traditional shoulder exercises such as the lateral and front raise will also engage the head.