cranial nerves

The cranial nerves are the 12 paired sets of nerves that arise from the cerebrum or brainstem and leave the central nervous system through cranial foramina rather than through the spine. The cranial nerves are numbered one to twelve, always using the Roman numerals, I to XII. Most have cranial nerve nuclei located in the brainstem.

Cerebrum

The first and second cranial nerves derive from the telencephalon and diencephalon respectively and are considered extensions of the central nervous system:

Midbrain

The third and fourth cranial nerves originate from the midbrain:

Pons

The middle four cranial nerves originate from the pons:

Medulla oblongata

The final four cranial nerves originate from the medulla oblongata:

In adults, the brainstem nuclei are located within the tegmentum, the posterior section of the brainstem (except in the midbrain where the quadrigeminal plate is most posterior).

See mnemonic for cranial nerves.

History and etymology

Thomas Willis (1621–1675) was responsible for the original numbering of the cranial nerves, as well as his famous anatomical circle in the brain.