What is the main function of the pectoralis major?

The main function of the pectoralis major is to adduct and medially rotate the humerus. This large muscle, located in the upper chest, plays a crucial role in movements of the arm. When engaged, it pulls the arm closer to the body (adduction) and turns the arm inward (medial rotation).

While the pectoralis major may assist with other movements, such as flexion of the arm at the shoulder joint, its primary and most distinct actions are adduction and medial rotation. Understanding the specific functions of muscles helps in applying appropriate techniques in massage therapy and kinesiology, making it easier to evaluate and treat various conditions related to shoulder and arm movement.