Briefly, what happens to my brain when I'm hit?

In most brain injuries, the brain ricochets or is "squished" against the skull during the impact of an accident. The nerve endings connected the skull to the brain are torn from one another or separated from the brain. Blood vessels may tear and leak blood into the brain. With localized damage, the brain bounces against the skull. When the brain is tossed back and forth against the skull (such as when you hit the car's steering wheel), the doctors know the injury as a contracoup injury.

Physical, behavioral, or mental changes that may result from brain trauma depend on the areas of the brain that are injured. Most injuries cause focal brain damage, damage confined to a small area of the brain. The focal damage is most often at the point where the head hits an object or where an object, such as a bullet, enters the skull.