The brain receives information from three distinct sources:

1. The endocrine axes.
2. The spinal nerves
3. The cranial nerves

This infographic explores the third source of information.

Loosely, cranial nerves exist because sensory information coming from the head doesn’t make much sense coming through the spinal cord.

Note that PSNS stands for Para-Sympathetic Nervous System (a branch of the autonomic nervous system).