Monteggia fracture-dislocations comprise of a fracture of the ulna shaft and dislocation of the radial head. The ulna fracture is usually very obvious whereas the radial head dislocation can be overlooked, with potentially serious functional and medico-legal ramifications. http://radiopaedia.org/articles/monteggia-fracture-dislocation
I read lots of articles about punching and the jury still seems to be out on whether punching is advisable or not in a self defence situation. Generally speaking if you have not taken time to condition your hands to impact, perhaps on a heavy bag or some kind of strike pad, then punching is not your best option in a fight.