The pectoralis major muscle is a large muscle in the chest that originates from the sternum (breastbone) and the clavicle (collarbone) and inserts into the upper arm bone (humerus). It is a powerful muscle that is responsible for several important movements of the upper body, including adduction, flexion, and rotation of the arm.
The pectoralis major muscle is divided into two parts: the sternocostal head and the clavicular head. The sternocostal head originates from the sternum and the ribs and is responsible for adduction and flexion of the arm. The clavicular head originates from the clavicle and is responsible for flexion and internal rotation of the arm.
The pectoralis major muscle is important for activities such as pushing, pulling, and lifting. It is also involved in activities such as swimming and throwing a ball.
Injury to the pectoralis major muscle can occur from overuse or from sudden, high-force movements, such as those that occur during contact sports. Treatment may involve rest, ice, physical therapy, and in some cases, surgery.