QUOTE (ptatc @ May 31, 2009 -> 12:42 PM)
The traps do go up the back of the neck. They are the thick muscles you feel when you put your hand on the back of your neck. They do not help the sides of the neck, these are primarily the scalenes. The only way to strengthen those is by sudebending your head. This really isn't advisable unless you are a bodybuilder as the exercises put a great deal of stress on the discs in your neck.
Since we're on the subject, I have the problem of occasionally pulling muscles in those areas, side of my neck, etc. Happens randomly, last time I was sitting around basically doing nothing when my neck started to hurt. Goes away after a day or two, but I keep wondering why I'm doing it or if there's anything that can be done to avoid it.