Which muscle is responsible for shoulder joint abduction?

The muscle responsible for shoulder joint abduction is the supraspinatus. This muscle is part of the rotator cuff group, located at the top of the shoulder. Its primary function is to initiate abduction of the arm, lifting it away from the body, particularly in the first 15 degrees of the movement. While other muscles contribute to shoulder abduction as the movement progresses, such as the deltoid, the supraspinatus is critical for starting the motion due to its anatomical position and function.

The pectoralis major is primarily involved in adduction and flexion of the shoulder, acting as a powerful chest muscle. The teres major plays a role in internal rotation and adduction but is not directly involved in abduction. The coracobrachialis assists in flexion and adduction of the arm but does not contribute significantly to the abduction movement of the shoulder joint. Understanding the functions of these muscles in relation to shoulder movement is essential in both anatomy and practical applications in exercises such as Pilates.