Brain damage injury, or "traumatic brain injury", happens when any force acts on the brain to cause damage. Brain damage injury occurs when the brain is shaken, hit with force, or is penetrated by an object. The force of shaking the brain or the head being hit against an object may cause swelling of the brain, or bleeding within the skull, which can compress some areas and prevent them from functioning. Brain damage injury may lead to loss of consciousness, coma and death, and may result in permanent brain damage, with a loss of function of certain body functions such as motor skills or communication. Most brain damage injuries occur through physical violence, motor accidents, falls or sports, but any accident where the head hits a surface or is shaken may result in brain injury. Penetration as a result of gunshot wounds, explosions or other weapons is also a significant cause of brain damage injury in the U.S.