3. CN VII/VIII Flashcards by J L

CN VII and CN VIII emerge from the brainstem at the ____, in line with the ____ of the medulla

CN VII - Facial Nerve
CN VIII - Vestibulocochlear Nerve

The nerves lie in the angle between the lateral pons and the inferior aspect of the cerebellum -
____

inferior pontine sulcus
postolivary sulcus
cerebellopontine angle

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POSTERIOR CRANIAL FOSSA

Internal acoustic meatus transmits CN ____ and CN ____

VII

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Early anatomists grouped CN ____ and ____ together given their similar courses

Facial nerve
Vestibulocochlear nerve

VII

VIII

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Both CN VII & VIII are vulnerable to impingement by benign ____
aka ____
as they enter the meatus
These benign neoplasms, encapsulated by the ____:
• Compromise ____ perception
• Cause ____
• May lead to ____ muscle weakness

acoustic neuromas
vestibular schwannomas
perineurium
acoustic
dizziness
facial muscle

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CN VII consists of two primary roots

The smaller division, or
nervus intermedius
Contains:
	• \_\_\_\_
	• Special sensory fibers (SVA - taste)
	• \_\_\_\_

The larger division, or motor root carries ____

preganglionic parasympathetics (GVE)
general sensory fibers (GSA)

brachial motor fibers (SVE)

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CN VII fibers either arise from, or project to, a number of ____

pontine nuclei

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The MOTOR NUCLEUS of the facial nerve
Gives rise to the ____ fibers, innervating ____ pharyngeal arch muscles, that constitute the ____ part of the nerve

Axons of the ____ exiting the nucleus wrap around the ____, forming the ____ of facial nerve

branchial efferent (SVE)
second
largest

lower motor neurons
abducent nucleus
internal genu

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SVA & GSA
The afferent fibers arise from primary cell bodies in the ____
within the temporal bone

Taste fibers terminate in
the rostral end of the ____

General sensory fibers terminate in the ____

GVE
Preganglionic parasympathetic fibers in the nervus intermedius arise from the ____

geniculate ganglion
nucleus solitarius (the gustatory nucleus)
spinal nucleus of CN V
superior salivatory nucleus

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CN VII transits the sub-arachnoid space and enters the temporal bone through the
____

Cochlear N.
Vestibular N.
Nervus intermedius

internal acoustic meatus

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Recall that CN VII courses through the
____
within the petrous portion of the temporal bone

facial canal

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Recall too that afferents in the ____ are central projections of ____
located in the geniculate ganglion

nervus intermedius

primary sensory neurons

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CN VII branches extensively within the
____

Geniculate ganglion
Nerve to stapedius
Chorda tympani
Greater petrosal nerve

facial canal

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The
GREATER PETROSAL NERVE
exits the temporal bone through the ____
into the middle cranial fossa

hiatus of the greater petrosal nerve

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GREATER PETROSAL NERVE

After exiting the fossa through ____, the nerve passes through the ____ to reach the Pterygopalatine ganglion

foramen lacerum

pterygoid (vidian) canal

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The ____ innervates the STAPEDIUS muscle

stapedial nerve

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The CHORDA TYMPANI is so named because it passes along the ____ wall of the ____

lateral

tympanic cavity

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Chorda tympani exits the cranium through the ____ at the medial end of the ____ to enter the infratemporal fossa

iter chordae anterius

petrotympanic fissure

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Recall that the ____ lies in the floor of the ____ of the temporomandibular joint

petrotympanic fissure

mandibular fossa

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Following the origin of these branches, the

FACIAL NERVE TRUNK exits the cranial base via the ____

stylomastoid foramen

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Fibers in the trunk of the facial nerve are primarily concerned with innervating the
MUSCLES OF ____… …as well as both:
- ____
- ____

facial expression
stylohyoid
posterior digastric

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TO SUMMARIZE…
Five distinct segments of CN VII may be defined within the facial canal

____
passes above the labyrinth housing the vestibular system

____
includes the geniculate ganglion

____ - travels posteriorly and laterally along the medial wall of the middle ear cavity

labyrinthe
external genu
tympanic

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TYMPANIC

Mastoid
gives rise to the nerve to ____ and the ____

stapedius

chorda tympani

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SVE fibers innervate ____ ARCH DERIVATIVES

Muscles of ____
____ & Posterior Digastric
____

second
facial expression
stylohyoid
stapedius

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Most SVE fibers in the trunk of the facial nerve ramify within the
____

parotid gland

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``` But don’t overlook the POSTERIOR AURICULAR nerve • ____ • ____ ```

occipitalis | auriculares

(PAINFULLY) TWO ZEBRAS BIT MY COCK

YA!

The PAROTID PLEXUS has five major sets of branches: TEMPORAL Ask patient to Raise ____ ZYGOMATIC Ask patient to Shut ____ tight ``` BUCCAL Ask patient to • Pucker ____ • Bare ____ teeth • Blow out or ____ ``` (MARGINAL) MANDIBULAR Ask patient to Bare ____ teeth CERVICAL Ask patient to Flare ____ skin

``` eyebrow eye lips upper whistle lower cervical ```

Tumors of the parotid gland may compress or destroy ____ nerve fibers Extension back toward the ____ and ____ should be carefully sought for any parotid mass

facial stylomastoid foramen facial canal

The GREATER PETROSAL NERVE conveys secretomotor fibers which, after synapsing in the ____, innervate the ____ gland, ____ and ____ mucosa and ____ glands.

``` pterygopalatine ganglion lacrimal nasal paranasal palatine ```

CHORDA TYMPANI conveys secretomotor fibers that synapse in the ____ and innervate ____ and ____ salivary glands.

submandibular ganglion submandibular sublingual

CN VII CHAIN FILL THIS OUT!

Entering the pterygoid canal, the greater petrosal nerve is joined by the ____ to form the ____

deep petrosal nerve | nerve of the pterygoid canal (vidian nerve)

Where do postganglionic parasympathetics arising from the pterygopalatine ganglion go? DEEP PETROSAL NERVE carries ____ fibers derived from the ____

postganglionic sympathetic | internal carotid plexus

LACRIMAL GLAND | The gland is innervated by postganglionic autonomic fibers which accompany the ____ branch of ____

zygomatic | V2

NASAL MUCOSA Nasal mucosa is innervated by postganglionic autonomic fibers which accompany ____ and ____ branches of V2

posterior lateral nasal | nasaopalatine

PALATINE GLANDS | These minor salivary glands are innervated by ____ autonomic fibers which accompany the ____ and _____ branches of V2

postganglionic greater lesser

The TASTE BUDS are microscopic specialized cellular arrangements around the gustatory nerve endings of CN _____, _____ and _____ They detect primarily _____- soluble molecules called _____ ``` TASTE BUDS are scattered widely over • The entire lingual _____ and sides of the tongue • _____ • Lingual aspect of soft palate • _____ ```

``` VII IX X water tastants dorsum epiglottis posterior oropharynx ```

Most taste buds are found in the troughs surrounding the _____, anterior and parallel to the _____ Some are found on the _____ and _____ as well FILIFORM PAPILLAE of the _____ contain _____ nerve endings only

``` circumvallate papillae sulcus terminalis fungiform foliate papillae anterior 2/3 general sensory ```

In seeking to understand sensory innervation of the tongue, we must distinguish between _____ and _____ modalities

``` taste (SVA) general sensory (GSA) ```

GUSTATORY RECEPTORS on the anterior 2/3 of the tongue convey information via the _____ to the geniculate ganglion and on to the _____ GENERAL SENSORY input from the filiform papillae of the anterior 2/3 of the tongue is conveyed via the _____

chorda tympani nucleus solitarius lingual nerve (V3)

Some sources claim that the _____ also carries some taste fibers from the mucosa of the soft palate – Other sources suggest the _____ conveys these fibers as well

greater petrosal nerve | chorda tympani

In addition to innervation of the occipitalis and some auricular musculature, the _____ also contributes to the complex _____ of the external ear

posterior auricular nerve | cutaneous innervation

The skin of the _____ (the hollow funnel leading to the EAM) A small patch of skin behind the ear... ...and a portion of the superficial aspect of the _____ (ear drum)

concha | tympanic membrane

We’ve discussed | BELL’S PALSY, resulting from a peripheral (infranuclear) lesion of _____ near, or distal to, the _____...

CN VII | stylomastoid foramen

Acute _____ paresis or paralysis of the facial muscles resulting from inflammation of the facial nerve and edema with compression Produced by viral infection (neuronitis) or vasospasm All actions of the ipsilateral facial muscles are affected, whether motivated by _____, reflex or _____ input Symptoms Include: Facial asymmetry with gravitational sagging of face and scalp due to loss of tonus of _____ Inability to wrinkle forehead on command due to paralysis of _____ Failure to retain tears and saliva in orbit and mouth respectively due to paralysis of _____ and _____ Retention of food in oral vestibule due to paralysis of _____

``` unilateral voluntary emotional facial muscles frontalis orbicularis oculi orbicularis oris buccinator ```

``` But the symptoms of either a _____ or _____ of CN VII may be more extensive depending upon the exact location of the lesion between the _____ and the _____ Other symptoms may include: • Reduced _____ • Hyperacusis • _____ • Diminished salivation ```

``` lower motor neuron infranuclear lesion pons stylomastoid foramen lacrimation dysgeusia ```

CN VIII – Vestibulocochlear Nerve Special Somatic Afferents (SSA) convey sensory input concerning sound from the _____ and equillibrium from the _____ of the vestibular system

cochlea | semi-circular canals

Recall that the organs of hearing and balance are embedded within the _____ PART of the TEMPORAL BONE or _____

petrous | petrous pyramid

Cartilaginous components laterally are continuous with the _____ and lead to the bony _____ - Ext auditory canal - Tympanic membrane - Tympanic cavity - Semicircular canals/vestibule of inner ear - Cochlea of inner ear

auricle | external auditory meatus

``` The MEMBRANOUS LABYRINTH consists of a series of communicating sacs and ducts suspended in the _____ within the _____ of the petrous temporal bone ``` The membranous labyrinth is separated from the surrounding bony labyrinth by _____ a CSF-like fluid

bony labyrinth otic capsule perilymph

``` The membranous labyrinth itself contains _____ and is divided into: • _____ • Saccule • _____ • Cochlear duct ```

endolymph utricle semicircular canals

CN VIII has distinct _____ and _____ portions

vestibular | cochlear

COCHLEAR (auditory) NERVE • Carries the _____ fibers for hearing • Composed of the central processes of neurons in the _____

SSA | spiral ganglion

Sound waves induce vibration of the _____ and _____ in the tympanic cavity ``` The baseplate of the stapes moves in and out of the _____ generating pressure waves within the _____ of the cochlea ```

tympanic membrane ossicles oval window perilymph

The cochlea consists of _____, side-by-side, concentrically coiled tubes which make 2.5 turns around the MODIOLUS Two of the tubes are continuous at the _____

three | helicotrema

The fluid wave travels through the fluids within the cochlea and distorts the basilar membrane of the _____, stimulating the _____ The hair cells transmit action potentials to bipolar neurons whose cell bodies are in the _____ of the cochlear n.

organ of corti hair cells spiral ganglion

_____ stimulation of hair cells in different areas along the basilar membrane results from different frequencies of sound

place principle

Central projections form the auditory portion of CN VIII to _____ located in the _____

cochlear nuclei | caudal pons

The cochlear nuclei are _____ organized Anterior cochlear nucleus - _____ frequency Posterior cochlear nucleus - _____ frequency

tonotopically low high

Acoustic inputs project to cortex in the _____ along the lateral sulcus, but the processing of bilateral acoustic inputs begins in the brainstem Time of _____ and _____ differences between left and right ears are analyzed to permit localization of sound sources

temporal lobe arrival intensity

Though CN VIII is generally described as containg special _____ only, it does in fact have an_____ component inhibiting _____ output produced by hair cell stimulation

afferent efferent afferent

____ contracts reflexively in response to loud sounds as well as just before we begin to speak STAPEDIUS is innervated by the ____ A relatively ____ intracranial lesion of CN VII leads to paresis or paralysis of stapedius producing ____

stapedius facial nerve proximal hyperacusis

VESTIBULAR NERVE • Responsible for controlling ____, balance and ____ • Composed of the central processes of bipolar neurons in the ____

posture equilibiru vestibular ganglion

The ____ enables perception of position and motion in relation to gravity, as well as the spatial orientation of both head and body in relation to vertical Peripheral processes of bipolar neurons in the vestibular ganglion covey inputs: 1) From the ____ of the ____ and saccule, ____, which detect linear acceleration and motion due to gravity and translational movement 2) From the ampullae of the ____- which detect changes in angular ____ and rotary acceleration of the head in any direction relative to the vertical during quiet stance

``` vestibular system maculae utricle otolithic organs semicircular canals motion ```

Because the vestibular system primarily provides sensory inputs about the head on the body, the CNS also relies on other ____ to determine overall body position and movement... ____ inputs convey information about movement with respect to the environment and the direction of vertical ____- coordinates eye movements to compensate for movements of the head so that ____ upon a chosen object may be maintained even as the head moves

sensory modalites visual VOR visual fixation

Because the vestibular system primarily provides sensory inputs about the head on the body, the CNS also relies on other sensory modalities to determine overall body position and movement... ____ convey inputs about ____ and ____, providing information concerning the relative alignment of body segments to each other and the support surface via innervation of the ____ of the posterior neck, back and lower limb to support the body against the pull of gravity

proprioceptors joint position muscle stretch extensors

"motion sickness"

CN VIII Lesions - Causes: - - ____ - - Meniere's disease (imbalance of endolymph) - ____ (benign tumor of schwann cells) - Symptoms: - - ____ - - tinnitus (ringing, whistling or booming) - - ____ - - vertigo (the illusory perception of motion) - - ____ - - nystagmus (rhythmic oscillation of the eyeballs) producing oscillopsia (jumping of visual environment)

viral labyrinthitis acoustic neuroma sensorineural deafness dizziness nausea/vomiting