Cranial nerves are part of the central nervous system and emerge directly from the brain, in contrast to spinal nerves which emerge from segments of the spinal cord. The cranial nerves are comprised of twelve pairs.

The first and second pairs emerge from the cerebellum; the remaining ten pairs emerge from the brain stem.

Traumatic and non-traumatic brain injuries can cause injury to these nerves through the same mechanisms which cause damage to brain tissue.

Damage to them affects many important functions throughout the body including vision, eye movement, the senses of smell and taste, facial expression, and hearing.