The pectoralis muscle is located at the front of your chest. It comprises:
- The pectoralis major – the larger of the two muscles which helps to move the arms in front of the body
- The pectoralis minor – a thin, flat muscle immediately underneath the pectoralis major which lifts the rib cage and moves the shoulder blade forwards
Both the pectoralis major muscle and its tendon (which attaches to the upper arm bone) can become torn. This is a fairly uncommon injury that mostly affects men aged between 20 and 50, particularly those who use steroids as they strengthen the muscle disproportionately to the tendon.