The cranial nerves are 12 paired nerves that arise from the brain and travel through foramina and fissures in the cranium to innervate various structures, primarily in the head and neck.

Just like spinal nerves, which originate from the spinal cord, cranial nerves originate from the brain, but unlike spinal nerves which are pretty similar to each other - with all of them being mixed nerves - the cranial nerves are a mix and match of motor, sensory and autonomic functions.

Simply put, some cranial nerves are motor nerves, some are sensory nerves, some are mixed and some carry parasympathetic fibers as well.

Funnily enough, some of them aren’t even nerves at all.

The first and second cranial nerves, which are the olfactory and optic nerves, are actually brain projections that belong to the olfactory and optic tracts, but everyone likes to call them cranial nerves so we will too!

Let’s start by naming the 12 pairs of cranial nerves in order from rostral, or front of the brain, to the caudal, or back of the brain, on an image of the ventral surface of the brain: 1st Olfactory, 2nd Optic, 3rd Oculomotor, 4th Trochlear, 5th Trigeminal, 6th Abducens, 7th Facial, 8th Vestibulocochlear, 9th Glossopharyngeal, 10th Vagus, 11th Accessory, and 12th Hypoglossal.

There are many mnemonics out there to help you remember these so choose one that best fits you, but here at Osmosis we like to remember these nerves by saying:

Oh Oh Oh To Touch And Feel Very Green Vegetables A H!

Now, these nerves don’t all originate from the same place and they enter or exit at different parts of the brain.

Cranial nerves one and two enter the cerebrum, but most of the cranial nerves enter or exit at various levels of the brainstem.