Traumatic Brain Injury
Traumatic brain injury (TBI) is the
term used to describe the damage to the brain suffered
as a result of a 
sudden physical force.
The human brain consists of billions of microscopic fibers, suspended in cerebrospinal fluid. While the exterior skull is smooth, the inner surface contains ribbing and pronounced bony structures. Impact with these inner surfaces of the skull causes tearing and bruising that results in brain injury.