Anterior BrainStem with Cranial Nerves

Ten of the twelve pairs of cranial nerves (CN) originate from the brainstem (midbrain, pons, and medulla oblongata). The two exceptions, CN I (olfactory) and CN II (optic), arise from the cerebrum/forebrain. Midbrain-pontine junction: The oculomotor nerve (CN III) emerges from the junction of the midbrain and pons. The trochlear nerve (CN IV) is unique as it emerges from the posterior (dorsal) side of the midbrain.

Pons

The trigeminal nerve (CN V) emerges from the lateral aspect of the mid-pons.

Pontomedullary junction

The abducens (CN VI), facial (CN VII), and vestibulocochlear (CN VIII) nerves emerge from the groove between the pons and medulla.

Medulla Oblongata:

Anterior to the olive

The hypoglossal nerve (CN XII).

Posterior to the olive

The glossopharyngeal (CN IX), vagus (CN X) and accessory (CN XI) nerves.