Last Updated: 04/4/18
For individual's with NF2, tumors are expected to grow on Cranial Nerve 8 (CN 8) - Vestibulocochlear Nerve; which controls hearing and balance. It is not
uncommon for tumors on CN 8, to also damage CN 7 the Facial Nerve. Tumors also commonly grow on the; Optic Nerve (CN 2), the Trigeminal
Nerve (CN 5), and Vagus Nerve (CN 10). It is possible for tumors to grow and damage any other cranial nerves as well. These nerves are sometimes
damaged as a result of Schwannoma, tumors that grow as a part of a nerve, but damage can also be the result of Meningioma, tumors that cause
damage as a result of intracranial pressure.
Many Cranial Nerves have more than one function, for example when a Schwannoma grows on the Vestibular Nerve; it results in loss of function of Hearing and Balance
since the Vestibular Nerve is very close to the Cochlear Nerve.
There are 12 pairs of nerves in the Central Nerve System, a left and a right nerve for each. Some control muscles and others control senses. The Cranial Nerves (CN) include:
- 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.