Midbrain
The CN X is the vagus also it is called pneumogastric nerve,the Wanderer or sometimes the Rambler
Cranial nerve 4 (IV) is the trochlear nerve.
Because somebody would ask why it wasn't cranial nerves instead of brainial nerves.
A cranial nerve is a nerve that passes through various foramina in the bones of the cranium and arise from the brain inside the cranial cavity.