If you’re a chiropractic student, even if you’re a first quarter or Tri 1, you probably will have heard of the 12 cranial nerves. Let’s do an overview of these special nerves and their functions!

Cranial nerves are a set of 12 paired nerves. Unlike other nerves which emerge from the spinal cord, cranial nerves differ because they directly arise from the brain, specifically the brainstem and the forebrain.

Something to keep in mind when studying cranial nerves, each pair has a number and they are denoted in roman numerals, one is I, two is II, three is III, etc. Each of the 12 cranial nerves also has a nickname, as you’ll see in the lists below.

Let’s cover some key points every chiropractic student should know, especially for their National Board of Chiropractic Examiners Board exams.

LOCATION OF ORIGIN

The brain and brainstem arise from different embryologically regions, called brain vesicles. These 5 vesicles (telencephalon, diencephalon, mesencephalon, metencephalon and myelencephalon) give rise to different neurological structures that the cranial nerves originate from. See below for which neurological structure each cranial nerve arises from.

1. Olfactory (I): Telencephalon (olfactory bulb)
2. Optic (II): Diencephalon (optic chiasm)
3. Oculomotor (III): Midbrain (mesencephalon)
4. Trochlear (IV): Midbrain (mesencephalon)
5. Trigeminal (V):
   • Ophthalmic division: Midbrain (mesencephalon)
   • Maxillary division: Pons
   • Mandibular division: Pons
6. Abducens (VI): Pons
7. Facial (VII): Pons
8. Vestibulocochlear (VIII): Pons
9. Glossopharyngeal (IX): Medulla oblongata
10. Vagus (X): Medulla oblongata
11. Accessory (XI):
    • Spinal accessory component: Spinal cord (spinal roots)
    • Cranial accessory component: Medulla oblongata
12. Hypoglossal (XII): Medulla oblongata

FORAMINA

Each cranial nerve exits out of a hole in the skull called a foramen. Below is a list of the foramina the 12 cranial nerves exit from.

1. Olfactory (I): None (extends directly from the olfactory bulb)
2. Optic (II): Optic canal
3. Oculomotor (III): Superior orbital fissure
4. Trochlear (IV): Superior orbital fissure
5. Trigeminal (V):
   • Ophthalmic division: Superior orbital fissure
   • Maxillary division: Foramen rotundum
   • Mandibular division: Foramen ovale
6. Abducens (VI): Superior orbital fissure
7. Facial (VII): Stylomastoid foramen
8. Vestibulocochlear (VIII): Internal acoustic meatus
9. Glossopharyngeal (IX): Jugular foramen
10. Vagus (X): Jugular foramen
11. Accessory (XI):
    • Spinal accessory component: Jugular foramen
    • Cranial accessory component: Foramen magnum
12. Hypoglossal (XII): Hypoglossal canal

FUNCTIONS

Here is an overview of each of the 12 cranial nerve functions.

1. Olfactory (I): Responsible for sense of smell
2. Optic (II): Responsible for vision
3. Oculomotor (III): Controls most eye movements and pupil constriction
4. Trochlear (IV): Controls movement of the superior oblique eye muscle
5. Trigeminal (V): Responsible for facial sensation and chewing
6. Abducens (VI): Controls the lateral rectus eye muscle
7. Facial (VII): Controls facial expressions, taste, and salivary glands
8. Vestibulocochlear (VIII): Responsible for hearing and balance
9. Glossopharyngeal (IX): Controls swallowing, taste, and salivary glands
10. Vagus (X): Involved in various autonomic functions, including heart rate and digestion
11. Accessory (XI): Controls neck and shoulder muscles
12. Hypoglossal (XII): Controls tongue movements

Learning and studying cranial nerves can be overwhelming. This is why our CAL board reviews have mnemonics, colorful drawings and charts to help you remember everything you need to know about our twelve cranial nerves. Want to check out our review courses? Go here!

We hope this blog post reminded you of some important facts about cranial nerves!

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