Rocketflip. The Shoulder has an amazing range of motion. This is the result of a complex design of both skeletal, and muscular structures. The primary components of the skeletal design of the Shoulder include, the Humerus (the bone of the upper arm) which orients itself proximally, to the Acromium Process, which is part of the Scapula (Shoulder Blades). The Clavicle (Collar Bone) is attached laterally to the Scapula, and medially to the Sternum (Breast Bone). The Scapula has a vast landscape that extends broadly along the posterior, thoracic region, and is rich with convoluted surfaces, and numerous, focused surface areas that serve as the points of attachments for the ligaments of its' muscular system. The Shoulder has a vast and complex array of muscles that serve to give the Shoulder its' tremendous Range of Motion (lateral, medial, upward/downward, as well as radial, in addition to anterior/posterior rotational motion). Some of the primary muscle groups responsible for the Shoulders movement are the Pectoralis Major/Minor, the Deltoid, the Biceps/Triceps, Latissumus dorsi, Teres minor, and posterior, the Trapezius, among other Muscle Groups of the Scapula, Neck and Costal Area (Ribs).