The scapula, or shoulder blade, is attached to over a dozen muscles, including the middle trapezius, lower trapezius, and rhomboids, located in your upper back. If these muscles are weak, your shoulders will hunch forward and add strain to your thoracic spine. These muscles act to retract the scapula, thus bringing the shoulder blades together. This movement is called scapular adduction, or scapular retraction.

Scapular retraction is an integral component of good posture. Completing simple scapular retraction exercises by squeezing your shoulder blades together and pulling your shoulders back, can strengthen your muscles and improve your posture.