Cranial Nerves

Question 1

CN IX

Answer 1

(Glossopharyngeal Nerve)
Nuclei:
-solitary nucleus (taste, visceral afferents)
-nucleus ambiguus (motor and parasympathetic)
-inferior salivatory nucleus (parasympathetic)
Function:
-taste from posterior 1/3 of tongue
-sensory to tympanic cavity, auditory tubes, upper pharynx,soft palate, posterior 1/3 of tongue
-visceral sensory from carotid sinus and body
-motor to stylopharyngeus muscle
-parasympathetic to parotid salivary gland
Lesion:
-loss of sensation (or intense pain) of upper pharynx
-reduced or absent gag reflex
-hypertension/hypotension

Question 2

CN X

Answer 2

(Vegas Nerve)
Nuclei:
-dorsal motor nucleus of the vagus (parasympathetic)
-nucleus ambiguus (motor)
-solitary nucleus (taste, visceral afferents)
Function:
-parasympathetic to thoracic and abdominal viscera (e.g.,
lungs, heart, GI tract)
-motor to pharyngeal constrictors, intrinsic laryngeal, palatalmuscles for phonation and swallowing
-taste from larynx and epiglottis
-sensory to larynx, a small portion of the external ear,
meninges in posterior cranial fossa and foramen magnum
Lesion:
-loss of parasympathetics to thorax and abdomen
-dysphonia, dysphagia

Question 3

CN XI

Answer 3

(Accessory Nerve)
Nuclei:
-nucleus ambiguus (motor)
-disperse cell bodies in medulla and cervical spinal cord
Function:
-cranial: motor to pharyngeal, laryngeal, and palatal mm (runs with the Vagus nerve)
-spinal: motor to trapezius and sternocleidomastoid mm.
Lesion:
-cranial: dysphagia, dysphonia
-spinal: paralysis of ipsilateral trapezius andsternocleidomastoid muscles

Question 4

CN XII

Answer 4

(Hypoglossal Nerve)
Nuclei:
-hypoglossal nucleus
Function:
-motor to muscles of tongue (except palatoglossus)
Lesion:
-ipsilateral tongue paralysis and atrophy

Question 5

CN V

Answer 5

(Trigeminal Nerve)
Origin/Level:
1. nucleus of the spinal tract of trigeminal [pain and
temperature] /midpons- C5
2. chief sensory nucleus [touch] /midpons
3. mesencephalic nucleus [proprioception] /midpons-midbrain
4. motor nucleus [muscles of mastication] /midpons
Exit:
-midpons
Peripheral branches:
-V1 ophthalmic (sensory)
-V2 maxillary (sensory)
-V3 mandibular (mixed)
Function:
-Sensory to the face, scalp, teeth, most of the
tongue, oral and nasal mucosa, dura mater and
cerebral blood vessels.
-Motor to the muscles of mastication (masseter,
temporalis, medial and lateral pterygoid muscles.
Examination: touch by cotton swab; pain by pinprick;temperature; corneal reflex; jaw reflex; masticatory
movements.
Lesion: trigeminal neuralgia (tic douloureux), facial
anesthesia or numbness, inability or difficulty to bite
down with jaw deviation to the same side.

Question 6

CN VI

Answer 6

(Abducens Nerve)
Origin: 
-abducent nucleus
Level: 
-lower pons at the level of the facial 
colliculus
Exit: 
-pontomedullary junction between basilar 
pons and pyramid
Function: 
-extraocular movements [lateral rectus muscle]
Examination: 
-lateral eye movements
Lesion: 
-diplopia, medial strabismus

Question 7

CN VII

Answer 7

(Facial Nerve)
Origin/ Level:
-facial nucleus [motor] / lower pons at the level of
the facial colliculus
-nucleus of solitary tract [taste and
parasympathetic]
-superior salivatory nucleus [parasympathetic]
Exit:
-cerebellopontine angle
Peripheral branches:
-temporal, zygomatic, buccal,marginal mandibular, cervical
Function:
-motor to the muscles of facial expression
-taste from the anterior 2/3 of the tongue via the chorda
tympani
-parasympathetic to the lacrimal and serous and mucous
glands of the nasopharynx, and the submandibular and
sublingual salivary glands (also via the chorda tympani).
Examination:
-facial expression movements and taste
Lesion:
-Bell’s palsy; lower motor neuron type of facial
paralysis [hyperacousis, unilateral facial paralysis with
inability to wrinkle the forehead, raise the eyebrow, shut
the eye, smile; tear flow over sagging lower eyelid, and
loss of taste from the anterior 2/3 of the tongue]
**An upper motor neuron type of facial paralysis involves thecontralateral lower half of the face.

Question 8

CN IV

Answer 8

(Trochlear Nerve)
Nucleus:
-anterior part of the periaqueductal gray at the level of the inferior colliculus.
Exit:
-inferior to the inferior colliculi after the nerve fibers decussate in the superior medullary velum
Function:
-innervation of the superior oblique muscle which turns the eyeball into a down and in position.
Lesion:
-inability to look down and in

Question 9

CN III

Answer 9

(Oculomotor Nerve)
Nuclei: anterior portion of the periaqueductal grayat the level of the superior colliculus
-Motor
-Edinger-Westphal (parasympathetic)
Exit:
-Interpeduncular fossa
Function:
-Motor to all extraocular muscles except lateral rectus
and superior oblique (medial rectus, superior rectus,
inferior rectus, inferior oblique and levator palpebrae
superioris)
-Parasympathetics to sphincter pupillae (constriction)
and ciliaris (accomodation)
Lesion:
-ptosis, lateral strabismus, mydriasis
(enlarged, unresponsive to light pupil), cycloplegia (enlarged, unresponsive to accomodation pupil)

Question 10

CN I

Answer 10

(Olfactory Nerve)
Function:
-Smell (sensory)
Lesion:
-Loss of smell (sensory)

Question 11

CN II

Answer 11

(Optic Nerve)
Function:
-Sight
Lesion:
-Loss of sight

Question 12

CN VIII

Answer 12

(Vestibulocochlear Nerve)
Nuclei: 
-vestibular nuclei (medulla & pons) 
-cochlear nuclei (medulla)
Function:
-balance and equilibrium
-hearing
Lesion:   
-vertigo, nystagmus, vomiting
-loss of hearing