I only just noticed today, but one of my back muscles is significantly smaller than the other. I thought maybe it was because I was turning my head to look into the mirror, but my girlfriend confirmed it too. I'm not talking a slight difference, in comparision it looks as though I have no muscle at all on my left side.
I looked it up, and as far as I can tell it is my lower trapezius, this one here;
Is there anyway I can even them out? Seems like such an odd muscle to lack on one side and not the other.