Lecture 7- CN I-VI Flashcards by Caitlyn Griffin

where is the axons of the olfactory receptor neurons in the PNS

sphenoethmoid recess of nasal cavity

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how often do the olfactory neurons regenerate

every 30-60 days

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what is the function of CN V fibers in olfactory epithelia

detect pungency

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what olfactory receptors define chemical identity

odorant receptor, mainly GPCR, less

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what are the characteristic of AP speed in CN I

nonmyelinated and thinnest axon (.2 mm)
slowest transmission speed

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what is the olfactory filia

20-30 axons bundle together

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where do olfactory filia cross and the function

cross the cribiform plate and synapse with olfactory bulb

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how are AP conducted in the olfactory bulb

synapse with mitral cell dendrite (pyramidal cells, neocortex)
glutamate and carnosine are released EPSP
centrifugal fibers

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what are centrifugal fibers in conduction of AP in olfactory bulb

negative circuit regulating odarant detection
adaptation to odors

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how does the AP reflect intensity of the stimuli

represented by frequency of AP

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what are the first three order neurons of the olfactory pathway

1- olfactory receptor neuron
2- mitral cell (olfactory bulb)
3- only sensation, no thalamic relay for conscious perception

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what is the olfactory pathway after the 3rd order neuron

anterior olfactory nucleus in olfactory tract
olfactory tubercle
piriform cortex
amygdala
periamygadaloid cortex
anterior parahippocampal gyrus

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where does the anterior olfactory nucleus in the olfactory tract cross over

anterior commissure

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what makes uo the piriform cortex

uncus
limbic lobe

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what is the function of the amygdala in the olfactory pathway

emotional learning, aversion

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what is the function of the anterior parahippocampal gyrus in the olfactory pathway

memory

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what makes up the primary olfactory cortices

piriform cortex
periamygdaloid cortex

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what makes up the primary olfactory cortex

hypothalamus
amygdala
hippocampus
thalamus

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what is the function of the hypothalamus for the olfactory cortex

drive

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what is the function of the amygdala for the olfactory cortex

emotional learning

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what is the function of the hippocampus for the olfactory cortex

memory

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what is the function of the thalamus for the olfactory cortex

relay station and coordination center

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what does the thalamus project to to have perception of flavor function

to olfactory association cortex in insula near gustatory cortex

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what happens in the 4th week for eye development

protrusion of optic vesicle from diencephalon

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what happens in the 5th week for eye development

optic vesicle folds in to form double layer optic cup ectoderm forms lens vesicle

what happens in the 6th week for eye development

optic cup inner layer = retina optic cup external layer = retinal pigment epithelia both layers grow ant to form ciliary body and iris lens vesicle = form lens ectoderm = cornea

what are the anatomic landmarks around the eye

ora serrata limbus

what are the structures in external and internal layers of the eye

sclera and cornea- limbus choroid capillaries: blood supply, absorb stray light retina and ciliary bodies: ora serrata

what is the function of the ciliary body

lens accommodation and aqueous humor secretion

what is the function of the iris

adjust light pass through

where is the aqueous humor

anterior to the lens

what is aqueous humor

secreted by epithelia in ciliary body drain into scleral venous sinus and then to venous drainage of the eye

what structure is impacted by glaucoma

increased secretion or blocked circulation of aqueous humor

where is vitreous humor

posterior to lens

what is vitreous humor

glass like humor in the eyeball

what increases intraorbital pressure to maintain eyeball shape

aqueous and vitreous humor

what structures helps the eye focus

cornea and lens by refraction of light by transparent structures

what is the shape and function of the cornea

convex anteriorly maintain intraocular pressure gross adjustment

what is the shape and function of the lens

biconvex only anterior is adjusted fine adjustments

how does the eye adjust to near sight

ciliary m contract lens loosen zonular fibers

how does the eye adjust to far sight

ciliary m relax lens tighten zonular fibers

what nerve controls the ciliary m

parasympathetic motor of CN III

what structure is affected by cataracts

degeneration of lens results to blindness

which germ layer develops the lens

ectoderm

what eye structure helps adjustment of brightness and image quality

iris and retina

what makes up the iris

pupillary dilator/constrictor pinhole effects

what controls the pupillary sphincter/constrictor pupillae

CN III

what controls the pupillary dilator pupillae

sympathetic

what is the function of pupillary sphincter/constrictor pupillae

decrease iris diameter - less light into the eye

what is the function of pupillary dilator pupillae

radiating spokes increase iris diameter - more light into the eye

what is the retina

major role in visual sensitivity adjustment

how does the retina adjust light

absorbing strayed light by pigmented epithelia

what cells form the outer synaptic layer of the retina

rods/cones- photoreceptors bipolar neurons

where do bipolar neurons in the retina receive info

from converging with photoreceptors

what cells form the inner synaptic layer of the retina

interneurons ganglion cells

what form the optic nerve

axonal bundles of ganglion cells in the optic canal

how does a blind spot work

optic disk - no photoreceptors fills in

what is fovea

center of macula .35 mm concentrated cones highest visual acuity

what is the macula

center portion of retina 3mm

what is macula degeneration

lost visual acuity legally blind

if the visual system is hyperpolarized with light exposure, what happens with neurotransmitters between the external and internal segments of photoreceptors

no glutamate is released

if the visual system is depolarized without light exposure, what happens with neurotransmitters between the external and internal segments of photoreceptors

release glutamate

what is the receptive field

one area in space visualized by each receptor maintained all the way to VI (retinotopy)

in the visual system what happens if the bipolar cell is "on"

active in light inhibited by glutamate metabotropic receptor

in the visual system what happens if the bipolar cell is "off"

inactive in light activated by glutamate ionotropic receptor

where is the first order neuron in the visual system

bipolar cell to converge with photon receptor (cones)

where is the second order neuron in the visual system

ganglions

what is the function of X/P/beta ganglion cells and where do they converge from

color and finer details cones

what is the function of Y/M/alpha ganglion cells and where do they converge from

motion and coarse patterns rods

what is the function melanopsin and where do they converge from

circadian rhythm, W/K type no convergence from bipolar cells

where is the third order neuron of the visual system

LGN in the thalamus

how is vision projected

Macula projects to occipital lobe LGN plus the superior retina provide the inferior visual field Meyer loop plus inferior retina through temporal lobe project superior visual field

where does it come from where does it project to what is the function of the dorsal stream

Y/M/alpha ganglion to parietal lobe: where (R dominant, memory of shape, location, motion) to med temporal: navigation to frontal: how (plan action)

where does it come from where does it project to what is the function of the ventral stream

X/P/beta ganglion to inf temporal: what (name of object) cont to project to med temporal

In the primary visual cortex, which side of the brain is best to identify the whole object and parts of the object

R- whole object L- parts of the object

what forms the L visual hemifield

R temporal and L nasal retina

what forms the R visual hemifield

L temporal and R nasal retina

what forms the optic chiasm

contralateral nasal retina axons

a pt presents with bitemporal hemianopia, what is it called and what could be the problem

tunnel view d/t the pituitary tumor compressing optic chiasm

a pt presents with L homonymous hemianopia, what is the impact on the visual field

lost visual field

where is teh tectopulvinar pathway from and what are the functions

tectum and midbrain pretectal/superior colliculus: coordinate eye mvmt pupillary reflex visual association are- dorsal stream

what is blindsight/riddoch's phenomena

V1 lost function entirely when still but has vision when in motion

where do CN III, IV, and VI cross the cranium

superior orbital fissure in the sphenoid bone

what innervates and action of levator palpebrae superioris

CN III common tendinous ring in post orbital wall upper eyelid (open eye)

what innervates and action of superior rectus

CN III lateral and upward

what innervates and action of inferior rectus

CN III lateral and downward

what innervates and action of lateral rectus

CN VI lateral

what innervates and action of medial rectus

CN III medial

what innervates and action of superior oblique

CN IV medial and downward

what innervates and action of inferior oblique

maxilla, CN III medial and upward

what is esotropia

ADD eyeballs CN VI palsy

what is exotropia

ABD eyeballs medial rectus strain or CN III palsy

what is hypertropia

elevated eyeballs CN IV palsy

what is hypotropia

depressed eyeballs inferior oblique strain or CN III palsy

what nuclei controls Vm of CN III

edwinger westphal

what is the efferent and afferent of the pupiillary light relfex

afferent: CN II (ganglion cells) efferent: CN III

what is the name, function and location in the cranium of the 3 branches of CN V

V1- opthalamic, Ss, superior orbital fissure V2- maxillary, Ss, foramen rotundum V3- madibular, Ss and Sm, foramen ovale

what are the somatosensory function of CN V

facial sensory chemical sensation of taste and smell

what are the somato motor function of CN V

mastication hearing swallowing speaking

what m is innervated by CN V that does mastication

temporalis, massester, medial and lateral pterygoids

what m is innervated by CN V that does hearing

tensor tympani

what m is innervated by CN V that does swallowing

tensor veli palatini

what m is innervated by CN V that does swallowing and speaking

digastric ant belly and mylohyoid

what other CN's shuttle off CN V

CN III CN VII CN IX