What is the primary role of the pectoralis major muscle?

The primary role of the pectoralis major muscle is to adduct and internally rotate the shoulder. This muscle, which is located in the chest, is integral to shoulder movements due to its anatomical position and structure. When the pectoralis major contracts, it pulls the humerus towards the body, facilitating adduction. Additionally, it plays a crucial role in internal rotation of the shoulder, allowing the arm to rotate towards the centerline of the body.

Understanding the muscle’s actions is vital for evaluating shoulder mechanics in various activities, such as pushing movements or lifting, where the pectoralis major contributes significantly. This knowledge also aids in rehabilitation and strength training, emphasizing exercises that target the adduction and internal rotation functions of the muscle.