A head injury may be the only injury (such as a single blow to the head from a blunt instrument) or it may be combined with other injuries (such as head and body injuries caused by an explosion).

A head injury may consist of a cut of the scalp, a concussion, a contusion, a fracture of the skull with injury to the brain, or a combination of these injuries.

If the skin has been broken, it is called an open head injury. If the skin has not been broken, it is a closed head injury. Both open and closed head injuries can be severe and life threatening.