Another muscle that effects our posture are the Pectoral muscles, the muscles of your chest. Are you seeing a theme here? 😐
The Anatomy - The pectoralis major muscle is a large muscle in the upper chest, fanning across the chest from the upper arm, across the collar bone and onto the breastbone (see image above). The two pectoralis major muscles, commonly referred to as the "pecs," are the muscles that create the bulk of the chest. A developed pectoralis major is most evident in men, as the breasts of a female typically hide the pectoral muscles.
A second pectoral muscle, the pec minor, hides beneath the pec major. The pectorals are predominantly used to control the movement of the arm, with the contractions of the pec pulling the arm across the chest (horizontal add