대흉근, or the pectoralis major, is a large muscle located in the chest. It plays a crucial role in the movement of the shoulder joint, allowing for actions such as pushing, lifting, and rotating the arm. This muscle is divided into two parts: the clavicular head and the sternal head, each contributing to different movements. Strengthening the 대흉근 is important for overall upper body strength and stability. Exercises like push-ups, bench presses, and chest flies specifically target this muscle. A well-developed pectoralis major can enhance athletic performance and improve posture, making it a key focus in fitness routines.