What is the main function of the pectoralis major muscle?

The pectoralis major is a large, fan-shaped muscle located in the upper chest, and its primary functions involve movement at the shoulder joint. The muscle is heavily involved in both flexion and adduction of the shoulder.

When we refer to shoulder flexion, it describes the action of raising the arm forward, which is facilitated by the clavicular head of the pectoralis major. Conversely, shoulder adduction refers to bringing the arm closer to the midline of the body, an action performed by both the clavicular and sternal heads of the pectoralis major. Together, these actions allow for a significant range of motion and positioning of the arm, playing a crucial role in various upper body movements and exercises.

Understanding the anatomical functions of muscles like the pectoralis major is essential for designing effective training programs that aim to enhance strength and functionality in the upper body. Therefore, recognizing that this muscle facilitates both shoulder flexion and adduction helps explain its importance in activities like pushing, lifting, and many compound movements.