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Flashcards in Unit II Deck (107)
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1

Cranial Nerve 0

chemoreceptors

2

Cranial Nerve I olfactory

one of oldest, by passes thalamus and goes to olfactory cortex first then thalamus

3

Where is CN 0 and CN I in the brain?

Telencephalon

4

Where is CN II in the brain?

Diencephalon

5

Where is CN III-XII except XI in the brain?

Middy
pons
medulla

rule of 4

6

Cranial nuggets (4 of them)

axons form CN nerve
all CN motor nerve=LMN
corticobular directly innervate CN V, VII, XI, XII
all CN have bilateral innervation except VII, XII

7

All cranial nerves have .. .?

2 nuclei
2 nerves

ipsilateral innervation except trochlear nerve (contralateral)

8

Nucleus of origin vs destination

cell body of fibers that make nerve

2nd order neuron for incoming sensory info

9

Brain stem lesion, ipsilateral vs contralateral

ipsilateral: cerebellar and cranial nerves
contralateral: corticospinal and dorsal column

10

Vision in general

only sensory system that provides accurate spatial info from a far

taste/touch=accurate but no distance
smell/hearing=distance but not accurate

11

Electromag spectrum

vision only encompasses small part of it

light is unidimentional, straight, and travels far=good for accurate distant sensory

12

LIght interaction with medium

refraction- light is bent and slowed
diffraction- light bounces around the object
absorption

13

Wavelength and frequency

inversely related

long wavelength, short frequency= decreased energy
short wavelength, inc frequency= increased energy

14

What determines saturation, brightness, color/hue

Wavelength= color/hue

amp= brightness

purity=saturation

15

eye anatomy

Outer: sclera/cornea

Intermediate:
ant chamber: behind cornea, front of iris/ciliary body
post chamber: behind iris/ciliary body, front of lens

inner: retina

16

Optical disk

blind spot, BV=no receptor there

17

Formation of image

flipped upside down and backward

18

Cells of retina

ganglion cell layer
bipolar layer
photoreceptor
amacrine/horizontal layer (lateral interneurons)

19

Lateral interneuron cells

inhibitory in the periphery

on ganglion cells vs off ganglion cells

20

Rods vs Cones

rods:
respond to all wavelengths of light
max sensitivity at 500nM
1 photoreceptor (rhodopsin)
light sensitive
for night vision in low light setting
less photon needed to elicit response thus daytime bleaches rods

cones:
responds to only certain wavelengths
blue, green, red, respond to 420,530,650 nM
3 photo receptors (iodopsin)
not light sensitive
for daytime vision (no cones=legally blind)
needs >100 photon to elicit response

21

Retinal conversion

only 1 million ganglion cells, over 94 rods/cones

rods:
high convergence=undetail
1 ganglion receives input from many rods
inc light gathering during night low light condition
inhibit spatial resolution (large receptive field)
no rods in fovea

cones:
low convergence=detailed
1:1 ganglion:cone
for acuity
spatial resolution (small receptive field)
almost all cones in fovea, few cones scattered too

22

Rods/Cones firing AP?

they don't fire AP

fire graded potentials (decay in time/space), (don't have enough sodium channels)

23

Ganglion cells in general

first cell in vision pathway to fire AP
axons of ganglion cell form optic nerve

projects to: LGN of thalamus, superior colliculus (retinofugal pathway), brainstem nuclei, suprachiasm nucleus of hypothalamus

24

Parasol vs Midget Cells

Parasol cells:
monochromatic
large cell bodies/receptive field
gross movement of stimulus
large fibers to LGN magnocellular layer (4cA)

Midget cells:
numerous
small cell bodies/receptive fields
fine detailed/color
small fibers to LGN parvocellular layer (4cB)

25

Normal path for visual perception

retina eye to LGN of thalamus to Visual cortex

info is divided at chiasm

shared at splenium

26

2 streams of info of vision

dorsal: tells us where
ventral: tells us what

27

Visual field affected by lesion

Optic nerve
Optic chiasm
Optic tract
Lower bank/meyer's loop
Upper bank/optic radiation

28

Most common eye symptom

double vision

other eye movement controlled by tectum

29

Intrinsic eye movement

iris spincter (parasymp of CN III)
pupillary dilator (ascending cervical sympth)
ciliary body (parasymp of CN III)

Vision of near object: ciliary body relaxes
Vision of far object : ciliary body contracts (bends lens to converge the divering light rays)

Dim light: pupillary dilator contract, iris sphinctor relax
Bright light: pupillary dilator relax, iris sphinctor contract

30

Extrinsic eye movement

Superior oblique- introsion- CN IV
Inferior oblique- extorsion- CN III
Superior/Inf/Medial rectus- CN III
Lateral rectus- CN VI