A TBI, or traumatic brain injury, is a type of injury that occurs when an external force causes internal damage to the brain, according to Wikipedia. It is also known as an intra-cranial injury.
TBIs are a significant cause of death and disability worldwide, according to Wikipedia. They can be mild to severe, and they can negatively affect an individual's speech, hearing, motor functions, breathing, emotions and behaviors. When the head comes in contact with a hard object, the skull's job is to protect the spongy, nerve-filled matter of the brain. Even if the skull is not fractured by the force of trauma to the head, the brain may bounce around within the bony structure of the cranium, scraping along the walls of the skull or knocking against them. This action alone, apart from a greater injury, can cause internal swelling, bleeding and loss of brain cells. In the worst case scenario, the medulla oblongata, or brain stem, which connects the entire brain to the spinal cord, can be severed from the spinal chord, causing severe paralysis or brain death.