The pectoralis major is a muscle divided into two parts: the clavicular and the sternal. Both sections add horizontally and medially rotate the humerus. That is, these muscles are in the region of the thorax which is the part of the body located between the neck and the diaphragm muscle and which houses the main organs of breathing and circulation. The thorax is the chest region, in other words. For this reason, we can say that if Abbie went to the hospital complaining of chest pain, the areas she is referring to are the pectoral and the sternal.
