A concussion is a type of traumatic brain injury, or TBI, caused by a bump, blow, or jolt to the head that can change the way your brain normally works. Concussions can also occur from a blow to the body that causes the head to move rapidly back and forth. They can occur in any sport or recreational activity and most occur without loss of consciousness. Most people with a concussion will recover quickly and fully, but for some, signs and symptoms of concussion can last for days, weeks, or longer.
The brain is an organ surrounded by fluid that floats inside the skull. The fluid acts as a shock absorber for minor impacts, but when the brain moves rapidly inside the skull, a concussion has technically occurred. In sports for instance, when a player is tackled and suffers whiplash, the hit causes the head to move faster and the brain to strike the inner skull wall. When the whiplash stops, the brain can also hit the opposite wall of the skull.