When a doctor thought I was showing a winged scapular - they tested the Long Thoracic Nerve to make sure it wasn't damaged or impinged.

In my case, the nerve was fine and the doctor thought the winging was a result of muscle imbalances (post surgery) and had me do a number of 'scapular stabilization' exercises. If you google that term, alot of exercises should come up....

Hope that helps.