Lecture 9. Cranial nerve - Part I Flashcards by Jessica Chambers

Where are the 1st, 2nd, and 3rd-order neurons for CN I to conduct the smell of the delicious food?

1st: olfactory receptor neuron
2nd: olfactory bulb, mitral cells
3rd: piriform and periamygdaloid cortex

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What is chemical sensation done by?

specialized chemoreceptors

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What detects internal chemical stimuli?

internal organ chemoreceptors

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What detects external chemical stimuli?

gustatory/taste receptors: oral cavity
olfactors receptor neurons: nasal cavity

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What CN has chemosensitive free nerve endings?

CNV - trigeminal nerve through somatosensory

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What kind of a neuron is an olfactory receptor neuron?

bipolar - 1 dendrite, 1 axon w cell body between

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How many olfactory receptor neurons are there?

3 MILLIONS

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How often do olfactory receptor neurons renew?

30-60 days (1-2 mo)

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Why can olfactory receptor neurons regnerate?

part of PNS

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Where is the olfactory nerve?

sphenoethmoid recess

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Where does the olfactory nerve course thorugh?

the cribiform plate to synapse with olfactory bulb (CNS)

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What type of cilia are in CN I?

immotile cilia - dont move

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What kind of axons does CNI have?

Smallest diameter axons, nonmyelinated (SLOW AP CONDUCTION, injured easily)

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Are transporters for olfactory nerve specific or non-specific?

Non-specific

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What receptor binds to odarants to transport them across the membrane?

odorant-binding protein

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Are receptors for Olfactorants specific or nonspecific?

SPECIFIC

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What are some receptors for different odorant?

G-protein
Odorant receptor

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What do the specific odorant receptors do?

conduct AP to CNS

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What do ~30 CN I axons form?

a filia

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What is a filia

for the same odorant

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What do filia synapse with?

a single mitral cell (same shape as pyramidal cells)

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What is a glomerulus?

small ball, where filia synapse with mitral cells

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Why are negative citcuits for the olfactory bulb important?

adaptation

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What are centrifugal fibers

efferent fibers that travel from higher brain centers to lower structures, in this case, from the brain to the olfactory bulb

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Can olfactory receptor neurons and periglomerular cells regenerate?

YES

What is the 1st order neuron in the olfactory projection pathway?

Olfactory receptor neuron

What is the 2nd order neuron in the olfactory projection pathway?

mitral cell in olfactory bulb

What are the 3rd order neurons in the olfactory projection pathway?

- piriform cortex (3): uncus, limbic lobe - periamygdaloid cortex (5)

Olfactory is the only sensation without what?

thalamic relay - for conscious proprioception

What important about the anterior commissure with the olfactory projection pathway?

axons from contralateral olfactory bulb form this

What is an uncus?

horn of temporal lobe

What is the (lateral) hypothalamus for?

drive (smell food -> salivate)

What is the hippocampus for?

memory

What is the insula for?

flavor, integrates taste and smell together

What are papillae?

gustatory organs of the tongue

How many types of papillae are there?

What is a circumvallate papillae?

for CN IX: chemical/somatosensory stimuli

Where are circumvallate papillae?

root of the tongue

How many circumvallate papillae do we have?

8~12 total

How many taste buds are in each circumvallate papillae?

~250 in each

The root of the tongue is what?

oral pharanx

The body of the tongue is what?

oral cavity

How many folate papillae do we have?

10 on each side of the tongue, lateral

How many taste buds are in each foliate papillae?

100-150

Where are foliate papillae?

half in body, half in the root of the tongue

What CN controls the foliate papillae?

- CN VII(body) / IX (root) for chemical stimuli - CN V (spicy foods!) / IX (root) for common somatosensory sensation

Where fungiform papillae?

mainly in body of tongue

How many fungiform papillae do we have?

200-300 in total

How many taste buds are in each fungiform papillae?

3-5 each

What stimuli do ffungiform papillae detect?

chemical

What CN control fungiform papilllae's chemical stimuli detection?

- CN VII for tongue and soft palate - CN X for epiglottis

How do fungiform papillae detect somatosensory stimuli?

CN V AND X

What CN detects spicy food for fungiform papillae?

CN V

What makes up a taste bud?

~100 taste receptor cells, not neurons

How long do taste buds last?

1-2 weeks

What are taste receptor cells?

apical microvilli

What kind of synapse do apical microvilli form?

- electric and chemical synapse * NOT WITH CN V

How many tastes are there?

technically 5

How many types of taste receptors are there?

Where are tastant receptors?

on the taste cells and in other internal organs

What conducts a salty taste?

leaking ion channels for sodium/potassium ions

What conducts a sour taste?

iontotropic channel with H+ depolarization

What detects a sweet/umami/ and bitter taste?

GPCR

What is "the 6th taste"

ammonium chloride, like salty or sour ion channels, allows us to avoid toxic food

Which peripherial nerve conducts the AP the slowest in our body, why?

CNI, smallest diameter non myelinated

What innervates the soft palate?

greater petrosal nerve

What are the ganglia of CN VII, IC and X?

1st order neurons

What is GG? What CN is it for?

Geniculate gangion for CN VII

What is IG? what CN is it for?

inferior ganglia for CN IX and X

Where is all signal conducted to? (2nd order neurons)

rostral solitary nucleus

Where is the CAUDAL solitary nucleus?

digestive tract

What innervates the tongue?

chorda tympani hikes on lignual n from posterior of mandibular fossa

What allow us to have an appetite and enjoy food?

hypothalamus

What allows us to detect unpleasant taste and vomit?

amygdala

What is the 2nd order neuron for the taste ipsilateral projection pathway?

solitary nucleus, reciprocal projections with other structures

What is the 3rd order neurons of the taste ipsilateral projection pathway?

VPM

Where does the signal go after the 3rd order neuron for taste?

projects to the insular lobe: primary gustatory cortex

Where is the primary gustatory cortex?

insular lobe

Where does CN V chemical sensation project to for taste?

S1 and reticular formation

Where is the nuclei of CN VII?

Lateral pontomedullary junction

What functional components does the facial nerve have (CN VII)?

All 4

Which CN have all 4 functional componenets?

CN VII, IX, X

What is the CNVII pathway?

exit internal acoustic meatus and terminal branches through the stylomastoid foramen

What is the order of the functional components from medial to lateral?

Sm, Vm, Vs, Ss

What is the smallest muscle in the body and its innervation?

stapedius, CN VII

What are the 6 terminal branches of CNVII?

- temporal - zygomatic - buccall - mandibular - cervical - posterior auricular

What is the component in charge of the terminal branches of CNVII?

What is the acronym for the terminal branches of CNVII?

Two Zebras Bite My Cookies

Where are fascial and scalp muscles?

superficial for facial expression

What CN VII facial muscle is deep?

buccinator, with parotid gland duct piercing though

How does UMN control the salp and face?

UMN has seperte control of scalp and face LMNS

What is the cingulate motor area in charge of?

level IV, dorsal motor nucleus of CNVII, bilateral scalp above eyebrow

What deep brain structures and level II help with fascial expression?

amygdala, basal nuclei, brainstem nuclei

What does LMN control with fascial muscles?

ipsilateral face and scalp

Is bells palsy UMN or LMN?

LMN - whole side of face flaccis

Which can still wrinkle the forehead - LMN or UMN?

UMN

What is intra- CN VII anastomosis?

a regional injury not affecting fascial expression

What is CNVII combining?

innervation of MOTOR UNITS (3-5 LMN innervations)

What is the inter CN V and CNVII anastomosis for?

proprioception of facial muscles

What fascial nerve anastomosis is shown in the pic he likes of the cadaver?

Infraorbital nerve and zygomatic branch

You drink hot coffee and burned your tongue with taste lost. How long will you gain the normal taste back?

1~2 weeks

A patient who is talking but his R-side face does not move, even above the eyebrows. What is your diagnosis? Why does the patient present such signs?

R Bell’s palsy LMN injury, both face and scalp droop