Last Updated: 10/10/18
Cranial Nerves: Basic Facts About
A cranial nerve (CN) is any of the twelve (12) paired nerves that arise from the lower surface of the
brain with one of each pair on each side and pass through openings in the skull to the periphery of the
The twelve cranial nerves include; 1) olfactory nerve, 2) optic nerve, 3) oculomotor nerve, 3) trochlear nerve,
4) trigeminal nerve, 5) abducens nerve, 6) facial nerve, 7) vestibulocochlear nerve, 8) glossopharyngeal
nerve, 9) vagus nerve, 10) spinal accessory nerve, 11) and hypoglossal nerve.
Cranial Nerves: And NF2
For individual's with neurofibromatosis type 2 (NF2), schwannoma tumors grow as a part of up to eight (8) of the
brains twelve (12) cranial nerves. Some individuals with NF2 only develop tumors on one pair of cranial nerves.
Variations of how and when tumors develop vary from person to person.
The hallmark location often used as part of the diagnosis criteria for individuals with NF2, are tumors along cranial
nerve 8 (CN8), the vestibulocochlear nerve. The functions of CN8 are hearing and balance. Growth of tumors
along CN8 can also damage CN7, the facial nerve. The function of CN7 is facial expression.
The complete list of cranial nerves individuals with NF2 commonly develop tumors on include:
- CN3: oculomotor
- CN4: trochlear
- CN5: trigeminal
- CN6: abducens
- CN7: facial
- CN8: vestibulocochlear
- CN9: glossopharyngeal
- CN10: vagal
- CN12: hypoglossal
- CN11: spinal accessory
Cranial Nerves: Functions
Each of the cranial nerves controls a specific function, sense, or sometimes both.
- CN I (Olfactory Nerve):
Meets brainstem at the Olfactory bulb for the sense of smell
CNI (Cranial Nerve 1), is the only Cranial Nerve that can regenerate completely if damaged.
- CN II (Optic Nerve):
Meets brainstem at the Lateral Geniculate nucleus for vision
CNII (Cranial Nerve 2), carries Vision to the brain. This nerve does not contain Schwann cells.
- CN III (Oculomotor Nerve):
Meets brainstem at the Oculomotor nucleus and Edinger-Westphal nucleus for the muscles of the eye
CN3, (Cranial Nerve 3) has two functions it controls:
CN IV (Trochlear Nerve):
Meets brainstem at the Trochlear nucleus, muscles for eye movement
- Levator Palpebrae Superioris Muscle: this muscle keeps the eyelids open
- Construction of the Pupils: adaption to changing light
CN IV (Cranial Nerve 4), controls eyeball movement, rotating, up, down, left and right.
CN V (Trigeminal Nerve), three (3) branches:
Meets brainstem at the Mesencephalic nucleus, Principal sensory nucleus, Spinal trigeminal nucleus, and Trigeminal motor nucleus.
CN VI (Abducens Nerve):
Meets brainstem at the Abducens nucleus for eye movement.
- Ophthalmic Nerve (V1): Muscles of the eyelids, eyebrow, forehead, and nose.
This branch affects the glands for tear production and mucous membrane of the nasal cavity.
- Maxillary Nerve (V2): Sensation from the maxillary, nasal cavity, sinuses and taste.
- Mandibular Nerve (V3): Face Sensations and Muscles for biting, chewing, and swallowing.
Lateral Rectus Muscle: lateral vision
CN VII (Facial Nerve):
Meets brainstem at the Facial motor nucleus, Superior salivatory nucleus, and Solitary nucleus.
CN VIII (Vestibulocochlear Nerve):
Meets brainstem at the Vestibular nuclei (w. subnuclei) and Cochlear nucleus (w. subnuclei).
- Muscle Control: Facial Expression
- Sensory Control: Taste sensations for the front 2/3 of the tongue; sensations of Sweet and Salty
CN IX (Glossopharyngeal Nerve):
Meets brainstem at the Solitary nucleus, the Spinal nucleus of the trigeminal nerve, lateral nucleus of vagal trigone,
Nucleus ambiguus, and Inferior salivatory nucleus for muscles of the tongue, tonsil, and pharynx.
- Cochlear Nerve: Hearing
- Vestibular Nerve: Balance
CN X (Vagus Nerve):
Meets brainstem at the Dorsal nucleus of vagus nerve, Nucleus ambiguus, Solitary nucleus, and Spinal trigeminal nucleus.
- Muscle Control: Control of the Stylopharyngeus Muscle, impairment of this muscles
can affect swallowing and speech.
- Sensory Control: Taste sensations from the back 1/3 of the tongue; sensations of Bitter and Sour
CN XI (Spinal Accessory Nerve):
Meets brainstem at the Spinal accessory nucleus, and Nucleus ambiguus for muscles used in neck and shoulder movement.
CN XII (Hypoglossal Nerve):
Meets brainstem at the Hypoglossal nucleus for muscles of the tongue.
- Muscle Control: Muscle control that controls heart rate, sweating, esophagus, and digestion, as well as many involuntary muscle movements
in the mouth, including speech, and breathing.
- Sensory Control: Feeling in the ear canal.
- Merriam-Webster Definitions. www.merriam-webster.com
Deora, Harsh, et al. "Rare cranial nerve schwannomas: A retrospective review of nontrigeminal, nonvestibular cranial nerve schwannomas."
Journal of Neurosciences in Rural Practice 9.2 (2018): 258