The entire arm rests on the ribcage
the shoulder girdle is only attached to the sternum
Your two arms are more attached to each other than they are to the rest of the body.This is either a terrifying or very liberating thought.
Your arms were designed to work in concert with your rib cage…
I like the term concert because sometimes the ribs and thoracic units have the same melody and purpose. Sometimes one takes the high note and the other takes the low note and harmonize, sometimes one is supposed to just take a rest and let the others carry the movement… and if a small instrument lets say a piccolo (or muscle) is too tight, too loud, off key, sharp and piercing is disruptive to the whole movement, well that’s a concert I don’t want to listen to.
In strange shoulders (4) I will explain why I dislike the term rib cage and prefer the term rib slinky, but the image lets you see how unattached the shoulder blade is to the body. it is capable anatomically of many motions, many angles, many resting positions based on gravity and posture and usage. Any one of those three corners can go up, down, inside, outside, rotate, be adhered to the tissues that connect to the rib cage underneath them, Resting position can be affected by the fit and style of bra a woman choses to wear, how heavy items are that are routinely carried, by bulking up of muscles anywhere around the joint.
Going back to Wolfe, Davis, and Starling , the bones, connective tissue and blood supply to the entire area are affected by usage, and by default, non usage. A shoulder can have just as much pain or dysfunction caused by a weak, poorly initiated muscle as it has from a muscle in spasm so strong that it has shut off its own blood supply…..and all the time, it, they rest on the ribs whose movement or lack thereof affects the function of the shoulder.
Want to try a new shoulder exercise? close your eyes and breathe…. feel the connection. Breathe deep sitting, standing, in a recliner, in your bed, lying on your stomach…. discover the magic of how breathing can change your shoulders.