Anatomy of Motion on Instagram: "The scapula has two main factors that determine its range of available movement. Firstly, regardless of the type of movement, the acromion must remain close to the clavicle because the AC joint tightly connects them. This also means that, in many cases, the AC joint serves as a center for scapular rotational movements. Secondly, the flat inner surface of the scapula must slide along the rib cage, which means it cannot move into it or too far away from it. These c