From: http://www.youtube.com/user/megaelectric1 My left sternocleidomastoid muscle is quite a bit larger than the one on the right side of my neck. I was in a car accident around 2 years ago but it has only grown bigger in the last year so I dismissed the idea that it was down to that. Last year I had been going to the gym so I decided that it is probably down to tension when lifting weights and whatnot as my left side is my dominant side i.e I'm left handed. Any doctor I've asked has either said they don't know or it's nothing to worry about but no one has actually offered any explanation nor solution. What is your opinion? What do u think I should do? I've never been for a massage, do you think that massage therapy would help?