The front of the brain is most frequently affected in a traumatic brain injury. That's because the skull's frontal region is sharp and bony, resulting in contusion (bruising) and bleeding in this area.

Another major cause of damage is shearing – the stretching or tearing of the tiny nerve cells that comprise the brain. Shearing – which can occur throughout the brain, including the brainstem and cortex – results in decreased arousal and attention and slowed processing of information.