Did you know that your scapula only has one bony attachment to the rest of your skeleton - and that is your collar bone. Now if you think about the amount of weight, pressure and strength your arm can create - that collar bone just doesn't seem big enough to handle the job.
But this is where the muscles that surround the shoulder and shoulder blade come into play and create the ideal mix of strength and flexibility the shoulder needs.
But in some people the muscles of the shoulder get out of balance, perhaps they become short and tight, or weak and under-active - and all of a sudden your shoulder just isn't working the same.
One example of this is scapula winging - see pic above left - which is when you see one shoulder blade or both popping out from your back in certain arm positions or when loaded in a certain way. But remember - some winging of the shoulder blade can be perfectly normal and part of how we get our arm where it needs to be - but in other cases it highlights that something may not be working as it should.
So what are some of the causes?
Well they range from serious nerve injury through to just tight muscles - but lets look at two common ones:
A short Pec minor and a weak Serratus Anterior.
Now thats a mouthful - but its pretty simple when you try to think about what these muscles do.
Pec minor - lives in the front of the shoulder/chest. It attaches to a part of your shoulder blade that pokes from the back to the front - and when this muscle shortens it tips the shoulder blade forward and rounds your shoulders in.
For your shoulder blade to move normally down and around the rib cage - this muscle needs to let go - otherwise things have to move in a different way. Winging can be one of those ways.