Final answer:
Shoulder horizontal abduction is performed by the posterior deltoid, infraspinatus, and teres minor muscles, part of the stabilization system of the shoulder.
Step-by-step explanation:
The muscles that perform shoulder horizontal abduction are primarily the posterior deltoid, the infraspinatus, and the teres minor. The posterior deltoid is responsible for lateral rotation and extension of the arm, while the infraspinatus and teres minor muscles are part of the rotator cuff, which is a group of muscles and their tendons that act to stabilize the shoulder. These muscles work in concert to abduct the arm at the shoulder joint when the arm is moved horizontally away from the body's midline.
Other muscles that perform shoulder horizontal abduction include the supraspinatus, infraspinatus, teres major, and teres minor.