Cranial Nerves — Canine Brain

Roots of the twelve cranial nerves are colored red (except olfactory nerves are not colored). Cranial nerves arise from the brainstem, except olfactory nerves which join the olfactory bulb. The trochlear nerve (IV) exits from the dorsal surface of the brainstem. Although it is regarded as a cranial nerve, the optic nerve (II) is embryologically and histologically an extension of the brain.