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It is hilarious that the shoulder is the most mobile part of the body, because it is so prone to chronic tightness. The irony is that the wild amount of mobility is a big part of what makes that area susceptible to immobility.

Allow me to explain…

The shoulder’s massive movement potential comes because it is actually made up of four different joints, all working in concert. The sternoclavicular, acromioclavicular, glenohumeral, and scapulothoracic joints all combine to allow for an arm bone that can wave around like a gas station tube man in a hurricane.

This number of options is lovely in theory, but it is also a lot to manage. All four joints have to work together to produce movement, which requires an intricate choreography of muscle engagement and coordination. If even one little muscle dancer is off their game it can throw off the entire production, causing a restriction. This can be hard to fix given the system’s complexity.

Understanding all four joints, their planes of motion, and which muscles help to move them is key to training shoulder strength and flexibility. This post on shoulder anatomy for aerialists and pole dancers breaks it all down.

In order to get all that mobility there is very little that firmly attaches the shoulder to the rib cage. There is only one skeletal connection between the arm and the torso at the sternoclavicular joint, where the collarbone meets the sternum. Everything else is just floating around over the ribcage, anchored only by muscles.

Adding to the mayhem, only two muscles actually join the arm bone to the torso: the pectorals and the latissimus dorsi. Granted, these are big beefy important muscles, but they are alone in anchoring the arm to the body. All of the other muscles that insert on the arm originate on the shoulder blade, which is itself extremely mobile. This makes the movement of the arm bone extremely dependent on the position of the shoulder blade.

And the shoulder blade itself is an issue, as we will see below.

All of these moving parts give the brain more to organize and manage. As discussed in my post on chronic tightness and muscle guarding, when the brain doesn’t feel confident that a joint is stable through its full range of motion, it will tighten up the muscles as a safety measure. This is much more likely with so little structural support.

We humans gain so much of our proprioceptive ability by using our eyes. If you have ever tried to balance on one foot or precisely touch one finger to a specific site on your body with your eyes closed, it is much harder.

This means that most of us are not so good at understanding the muscles and joints in our back. They are very difficult to see or to touch with our hands and most of the time we have no idea what’s going on back there and it never occurs to us to ask.

Shoulder blade positioning is vitally important to arm movement. If the shoulder blades aren’t rotating and adjusting we end up putting way too much pressure on the glenohumeral joint (the shoulder socket itself) and this leads to myriad common problems like pinched nerves, rotator cuff tendonitis and tears, and impingement.

Most folks don’t invest time in training shoulder blade control and awareness, but if you are interested in increasing shoulder mobility, especially with weight bearing, this is essential work.

In my shoulder-focused classes we do a lot of work to separate the work of the shoulder socket from the movement of the shoulder blade, allowing for more awareness and control. We will be doing that in Saturday’s Intro to Contortion livestream. We will be doing stuff like this:

Of course, if you are fiddling around with shoulder blade position we also need to talk about the rib cage and thoracic/cervical spine, since all of the shoulder blade muscles anchor there. That means that just as arm bone movement is dependent on shoulder blade position, so shoulder blade movement is dependent on rib cage/spine position.

I know, it’s exhausting to have a body.

Next week’s post is going to dive into the upper back and rib cage and how our breathing patterns affect spinal flexibility. I can’t wait either!

Happy Bendings,

Kristina

Further reading:

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