AXIAL MUSCLES ANATOMYThe main muscle which is attributed to keeping the humerus attached to the pelvic girdle is the large muscle known as the pectoralis major. This fan shaped muscle is the key flexor muscle located within the pectoral girdle.
The latissimus dorsi is the large muscle, shaped very much like a triangle and relatively flat in appearance, which seems to blanket the inferior section of the thoracic area of the back.
Often referred to as the “swimmer’s muscle” given its significant impact on the shoulder joint and its overwhelming power when compared to other muscles of the same joint, the latissimus dorsi is the opposing antagonistic muscle to the pectoralis major muscle.
The extension that this muscle exerts on the shoulder joint is in essence “backwards,” drawing the shoulder joint to a increased angle through retraction.
AXIAL MUSCLES DIAGRAM
Image: Axial Muscles