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Neuroscience > Cranial Nerves Part 1 > Flashcards

Cranial Nerves Part 1 Flashcards

1, 2, 3, 4 and 6

1
Q

where are olfactory receptor cells located?

A

olfactory epithelium in the roof of the nasal cavity (ethomoid)

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2
Q

what is the olfactory epithelium composed of?

A
  1. olfactory sensory/receptor cells (hair cells)
  2. supporting cells
  3. basal stem cell
  4. olfactory glands
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3
Q

describe the structure of an olfactory sensory cell

A

bipolar neurons w/cilia (olfactory hairs) on the end of dendrite

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4
Q

T/F: the olfactory sensory/receptor cells are referred to as hair cells but are not neuron

A

FALSE
these ARE neurons

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5
Q

describe the supporting cells in the olfactory epithelium. What are they and what is their function?

A

mucous membrane lining of nasal cavity, neuroglia cells

function is to support, nourish, insulate, and detoxify olfactory receptor cells

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6
Q

what is unique about basal stem cells in the olfactory epithelium?

A

these are neuronal stem cells

olfactory receptor cells have a lifespan of 1 month and are then replaced

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7
Q

what is the function of the olfactory glands?

A

provide mucous to cover surface of olfactory epithelium to dissolve odor molecules so that they can interact with receptor cells

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8
Q

Describe the olfactory pathway up to the point that an AP is generated on CN 1

A
  1. odor molecule dissovles in mucous of nasal surface
  2. odor molecule binds to olfactory receptor protein (ligand binding)
  3. chemical interaction w/olfactory receptor opens chemical gated channels (Ca and Cl)
  4. graded potential on dendrite/soma in olfactory epithelium
  5. graded potenials sum at axon hillock to generate and AP on axon of olfactory receptor cell
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9
Q

describe the olfactory pathway from when an AP on CN 1 is generated to integration

A
  1. CN 1 axon goes through the cribiform plate to olfactory bulb
  2. signlas from olfactory receptor cell activate multiple cells in olfactory bulb for processing signals and discriminating signals
  3. olfactory bulb changes the pattern of signaling in response to a new odor
  4. olfactory tract carries new pattern to:
    1. ipsi and contralateral limbic structures
    2. temporal cortex
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10
Q

T/F: the olfactory bulb is always sending signals

A

TRUE

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11
Q

List the various ipsi and contralateral limbic structures

A
  1. Amygdale
  2. Entorhinal cortex
  3. hippocampus
  4. prefrontal cortex
  5. Insula
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12
Q

where is odor discrimination occuring?

A

temporal cortex

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13
Q

List the accessory structures of the eye

A
  1. eye lid
  2. eye brow
  3. eye lashes
  4. muscles
  5. lacrimal apparatus
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14
Q

what is the function of the eye lid?

A

protect the eye

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15
Q

what muscles and nerves are responsible for closing the eye lid?

A

obicularis occuli orbital and palpebral regions

CN VII

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16
Q

what muscles and nerves are responsible for opening the upper eyelid?

A

levator palpebrae superioris

CN 3

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17
Q

what is the inner lining of the eyelid called?

A

palpebral conjuctiva

it is continuous with the sclera

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18
Q

what is the function of the lacrimal apparatus?

what controls it?

A

produce lacrimal fluid (tears)

secreted superior/lateral and will flow diagonally to inferior/medial lacrimal canals which empty into nasal cavity

CN 7

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19
Q

List the extrinsic eye muscles

A
  1. Superior rectus
  2. inferior rectus
  3. lateral rectus
  4. medial rectus
  5. superior oblique
  6. inferior oblique
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20
Q

the eyeball can be divided into what 3 layers?

A
  1. fibrous outer layer
  2. Vascular middle layer
  3. retina-inner layer
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21
Q

what makes up the fibrous outer layer of the eyeball?

A

sclera (white CT covering the eye)

cornea

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22
Q

what is attached to the sclera?

A
  1. palpebral conjuctiva of eyelid
  2. dural sheath (epineurium) of CN 2
  3. tendons of extraoccular muscles
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23
Q

what is the cornea?

A

avascular area covering the anterior surface of the eyeball

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24
Q

what is another name for the vascular middle layer of the eyeball?

A

uveal tract

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25
Q

the uveal tract can be divided into what 2 layers?

A
  1. choroid
  2. ciliary body
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26
Q

what is the choroid layer of the uveal tract?

A

middle layer containing blood vessels for the eyeball

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27
Q

what is the ciliary body?

A

anterior modification of choroid containing 3 structures

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28
Q

what 3 structures are in the ciliary body?

A
  1. ciliary processes
  2. ciliary muscles
  3. Iris
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29
Q

what are ciliary processes?

A

a circular ridge attached to supspensory ligaments which connect to the lens

contain capillaries and produce aqueous humor

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30
Q

what are ciliary muscles?

A

circular smooth muscle at the base of ciliar process that changes the shape of the lens by pulling on suspensory ligaments

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31
Q

what happens to the lens to allow us to have near vision?

A

decreased tension on the lens resulting in a convex surface

made possible by contraction of ciliary muscles

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32
Q

what happens to the lens to allow us to have far vision?

A

increased tension on the lens resulting in a flat surface

made possible by relaxation of ciliary muscles

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33
Q

which is less tiring on the eyes? Near or Far vision?

A

Far vision, it is a passive process (ciliary muscles relax)

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34
Q

what is the Iris?

A

area of eye color

smooth muscle fibers that change size of pupil

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35
Q

what is the function of the pupil?

A

opening through which light enters eyeball

36
Q

what constricts the pupil?

A

circular muscles

parasympathetic (CN 3)

37
Q

what dilates the pupil?

A

radial muscles

sympathetic (carotid plexus)

38
Q

what is located at the retina inner layer of the eyeball?

A

neuron sensory receptor cells

*the beginning of the visual pathway

39
Q

list the structure/layers of the retina-inner layer

A
  1. pigment epithelium
  2. photoreceptor layer
    1. rods
    2. cones
  3. outer nuclear layer
  4. outer synaptic layer
  5. inner nuclear layer
  6. inner synpatic layer
  7. ganglion cell layer
40
Q

which portion of the retina has the sensory receptors in it?

A

photoreceptor layer:

rods = dim light, gray images

cones = bright light, color images

41
Q

where are the soma for the rods and cones located?

A

outer nuclear layer

42
Q

where does initial image processing occur?

A

inner nuclear layer of the retina

43
Q

there are several specialized areas of the retina, list them

A
  1. optic disc
  2. macula lutea
  3. ora serrata
44
Q

what is the optic disc?

A

blind spot

where optic nerve and blood vessels enter/exit the eyeball

**no sensory receptors here!

45
Q

what is the macula lutea?

A

visual axis/focal point

contains the central fovea

46
Q

why is the central fovea significant?

A

contains only cones

serves as area of highest visual resolution

47
Q

where is the lens and what is it’s function?

A

connected by suspensory ligaments to ciliary process/muscles

function = bend light to focus image on retina

48
Q

what is the virtreous body (humor) and what is it’s function?

A

located between lens and retina

holds retina in place

contains phagocytes that remove floating debris

49
Q

what is the anterior cavity of the eyeball?

A

area between cornea and lens

contains aqueous humor which nourishes the lens and cornea

50
Q

how is light directed to the retina?

A

through a refraction of light rays that can be altered via the processes of accomodation and convergence

51
Q

where is refraction of light rays occuring?

A

cornea and lens

52
Q

T/F: images are invereted upside down and reversed right to left during refraction?

A

TRUE

53
Q

what is accomodation?

A

the process by which the curvature of the lens is changed to focus light rays on the retina

54
Q

List and briefly describe several vision deficits that impact the refraction process

A
  1. myopia (nearsightedness) = distant object is unclear because image is focused in front of retina
  2. hypermetropia (farsightedness) = near object is unclear because image is focused behind retina
  3. presbyopia = lens becomes less elastic w/age and thus less convex, moving focal point further away from eyes
55
Q

what is the process of convergence?

A

process of moving eyes medially for near vision so that images of objects hit the equivalent spot in both retinas

necessary for maintaining proper overlap in visual fields of both eyes for binocular vision

56
Q

what does binocular vision allow for?

A

depth perception

3D perception

57
Q

Briefly describe the light pathway

A
  1. Light
  2. Object
  3. reflected light
  4. corena
  5. aqueous humor
  6. lens
  7. vitrous body
  8. retina
    1. pigment cells = absorb light
    2. photoreceptor cells = transduce light to nerve impulse
58
Q

Describe the inital route of the visual pathway leading up to the optic chiasm

A
  1. photoreceptor cells generate either excitatory or inhibitory impulse (graded potential)
  2. signal is processed and modified (via convergence and divergence) as it moves through neurons of other retinal cell layers
  3. AP is generated in ganglion cells
  4. AP exits eye by optic nerve
  5. optic nerve goes to optic chiasm
59
Q

impulses from which half of the retina cross to the opposite side of the brain at the optic chiasm?

A

from the Nasal half of retina

(temporal half stay ipislateral)

60
Q

after the optic chiasm, where does the AP travel next in the visual pathway?

A

optic tracts that head to:

  1. pretecal area → pupillary reflex
  2. superior colliculus → horizontal tracing eye movements and head turning
  3. lateral geniculate nucleus of thalamus
61
Q

the left optic tract is carrying visual info from which visual field?

A

Right visual field

(Left temporal and Right nasal retina)

62
Q

the right optic tract is carrying visual info from what visual field?

A

Left visual field

(Right temporal and Left nasal retina)

63
Q

where does the visual pathway head next after the lateral geniculate nucleus?

A

to visual cortex in the medial occipital lobes

via the optic radiations

64
Q

All external eyes muscles originate and insert where?

A

originate = orbital bone

insert = sclera

65
Q

what is the action and innervation of the

Levator palperae superioris?

A

action = elevate eye lid (open)

innervation = CN 3

66
Q

what is the action and innervation of the

Orbicularis occuli?

A

action = depress eye lid (close)

innervation = CN 7

67
Q

what is the action and innervation of the

Superior oblique?

A

actions:

  • when eyes are adducted (in near focus) = futher adduct
  • when eyes are abducted (far focus) = further abduct
  • depress and medially rotate eye

innervation = CN 4

68
Q

what is the action and innervation of the

Inferior Oblique?

A

action:

  • eyes adducted (from near focus) = further adduct
  • eyes abducted (from far focus) = further abducted
  • elevate and laterally rorate

innervation = CN 3

69
Q

what is the action and innervation of the

Superior rectus?

A

action: elevate (slight adduct and med rotate)

innervation = CN 3

70
Q

what is the action and innervation of the

Inferior rectus?

A

action = depress (slight adduct and lateral rotate)

innervation = CN 3

71
Q

what is the action and innervation of the

Medial rectus?

A

action = adduct

innervation = CN 3

72
Q

what is the action and innervation of the

Lateral rectus?

A

action = abduction

innervation = CN 6

73
Q

CN 3 innervates what eye muscles?

A
  1. Levator palpebrae superioris
  2. Inferior oblique
  3. Superior rectus
  4. Inferior rectus
  5. Medial rectus
74
Q

CN 3 is made up of what types of neurons?

A
  1. somatomotor → to skeletal muscle
  2. visceromotor (sympathetic) → to smooth muscle and glands
75
Q

where are the nuclei for CN 3 located?

A

Brain stem at the level of the midbrain

somatomotor = oculomotor nucleus

parasympathetic nucleus = Edinger-Westphal nucleus

76
Q

Briefly describe the pathway of the oculomotor nerve (CN 3)

A
  1. Nuclei in brainstem
  2. exits cranial cavity via superior oribital fissure
  3. divides into 2 branches
    1. superior division (uncrossed/ipsilateral)
    2. inferior division (uncrossed/ipsilateral)
77
Q

what does the superior division of the occulomotor nerve supply?

A

superior rectus

levator palpebrae

78
Q

what does the inverior division of the oculomotor nerve supply?

A

inferior rectus

medial rectus

inferior oblique

ciliary ganglion

79
Q

what is the ciliary ganglion?

A

parasympathetic gangia sending fibers to:

  1. ciliary body/ciliary muscles → accomodation
  2. circular muscles or iris → pupil constriction
80
Q

What types of neurons make up CN 4?

A

somatomotor → to eye muscles

somatosensory → proprioception

81
Q

Describe the pathway of CN 4

A
  1. Nucleus = brainstem at level of midbrain
  2. Crosses pre-tectum
  3. exits via cranial foramen (superior orbtal fissure)
  4. supplies contralateral superior oblique
82
Q

what types of neurons make up CN 6?

A

somatomotor to lateral rectus muscle

83
Q

Describe the pathway of CN 6

A
  1. brain stem nuclei at level of open medulla/pons
  2. exits via superior orbital fissure
  3. remains ipsilateral and innervates the lateral rectus muscle (abducts eye)
84
Q

Describe the pathway for the pupillary light reflex

A
  1. Light
  2. ganglion cells
  3. optic nerve/optic tract
  4. pre-tectal area
  5. Edinger-Westphal nucleus on both sides
  6. parasympathetic preganglionic
  7. ciliary ganglia
  8. parasympathetic postganglionic
  9. contracts circular muscle of iris
  10. Pupil constricts
85
Q

T/F: if you shine a light on the L pupil both pupils will constrict?

A

TRUE

via concensual pupillary light reflex (for R pupil)

(direct pupillary light reflex for the L pupil)

86
Q

What 3 pathways make up the accomodation reflex?

A
  1. Motor pathway resulting in convergence of visual field
  2. papillary constriction reflex
  3. Edinger-Westphal is activates resulting in an increased curved lens for near vision

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