Is a concussion a brain injury?

A: According to WebMD, a concussion is a mild traumatic brain injury & can be defined as a short-lived loss of brain function due to head trauma that resolves spontaneously.  With concussion, function may be interrupted but there is no structural damage to the brain.

However, if there is sufficient force to cause the brain to bounce against the rigid bones of the skull, then there is potential for injury. It is the acceleration and deceleration of the brain against the inside of the skull that can cause the brain to be irritated and interrupt it's function. The acceleration can come from a direct blow to the head or face, or from other body trauma that causes the head to shake.  While temporary loss of consciousness due to injury means that a concussion has taken place, most concussions occur without the patient being knocked out.  Studies of football players find that the majority aren't aware that they had sustained a head injury.