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Neuroanatomy and Physiology > Lecture 9a- Cranial Nerves 1,2,3,4,6 > Flashcards

Lecture 9a- Cranial Nerves 1,2,3,4,6 Flashcards

1
Q

OLFACTION (SMELL)

A

OLFACTION (SMELL)

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2
Q

Olfaction is a _________ interaction between molecules in air with ________ receptors on the membranes olfactory receptor cells (neurons) in the nasal cavity.

A
  • chemical

- chemo

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3
Q
  • What makes up the roof of the nasal cavity?

- It has 10-100 million olfaction receptor cells (_______) located in a sensory organ called the __________________.

A
  • ethmoid
  • hair cells
  • olfactory epithelium
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4
Q

The olfactory epithelium is a sensory organ composed of what 4 main parts?

A
  • olfactory sensory/receptor cells (hair cells)
  • supporting cells
  • basal stem cells
  • olfactory glands
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5
Q

-Olfactory sensory cells (hair cells) are bipolar _______ with what on the end of the dendrite?

A
  • neurons

- cilia (olfactory hairs)

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6
Q

What is different about the hair cells of the olfactory system and the hair cells of the cochlea and vestibular system?

A

The hair cells of the olfactory system are neurons while the ones for cochlear and vestibular function are not neurons

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7
Q

The supporting cells are _________ since the olfactory cells are neurons. The supporting cells function is to do what?

A
  • neuroglia
  • The supporting cells are the mucous membrane lining of the nasal cavity that support, nourish, insulate, and detoxify olfactory receptor cells.
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8
Q
  • The basal stem cells of the olfactory epithelium are constantly undergoing what?
  • What is the life span of a olfactory receptor cell?
A
  • constantly undergoing replication to replace olfactory receptor cells
  • 1 month
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9
Q

What is the function of the olfactory glands?

A

-dissolve odor molecules so transduction can occur, odor molecules must be dissolved before they can interact with olfactory receptor cells

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10
Q

A relatively small number of olfactory receptors recognize ________ different scents by stimulating unique ________ of receptors.

A
  • 10,000

- combinations

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11
Q
  • What is adaptation in regards to the olfactory system?

- When does 50% of adaptation occur?

A
  • process by which we decrease our sensitivity to continuous exposure to a particular odor
  • first second of exposure
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12
Q

What are the 9 steps in the olfactory pathway?

A
  1. ) odor = molecule in the air
  2. ) odor molecule dissolves in mucous of nasal surface
  3. ) odor molecule binds a combination of olfactory receptor proteins
  4. ) chemical interaction with olfactory receptor opens chemical gated channels (Ca and Cl)
  5. ) graded potential on dendrite/soma in olfactory epithelium = CN1
  6. ) AP on axon of the olfactory receptor cell = CN1
  7. ) CN1 axon goes through cribriform plate to olfactory bulb
  8. ) signals from olfactory receptor cell activate multiple cells in olfactory bulb which is layered for PROCESSING SIGNALS
  9. ) olfactory tract carries new pattern of signals from olfactory bulb to ipsi and contralateral limbic structures for the REFLEX RESPONSE TO ODOR, also goes to temporal cortex for odor discrimination
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13
Q

What is the function of the olfactory bulb?

A

Layered for:

  • processing signals
  • topographically representative of the olfactory epithelium for discriminating signals
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14
Q

The olfactory tract carries signals from the olfactory bulb to what structures?

A

Ipsi and Contralateral Limbic Structures

  • amygdala, hippocampus, prefrontal cortex
  • insula for emotional response to odors = reflex response to odor

Temporal Cortex
-either directly or via thalamus for odor discrimination

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15
Q

ACCESSORY STRUCTURES OF THE EYE

A

ACCESSORY STRUCTURES OF THE EYE

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16
Q

What are the 5 accessory structures of the eye?

A
  • eye lid
  • eye brow
  • eye lashes
  • muscles
  • lacrimal apparatus
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17
Q

What is the function of the eye lid?

A

protection of the eye

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18
Q

What are the two parts of the orbicularis oculi that function to close the lid? What nerve innervates them?

A
  • palpebral (soft) and orbital (hard)

- CN7

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19
Q

What muscle functions to open the upper eye lid? What nerve innervates it?

A
  • levator palpebral superioris

- CN3

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20
Q

What is the inner lining of the eye lid called?

A

palpebral conjuctiva

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21
Q
  • What is the function of the lacrimal gland?

- Why do we get the sniffles when crying?

A
  • produces lacrimal fluid (tears)

- lacrimal fluid runs from superior/lateral to inferior/medial lacrimal canals which empty into the nasal cavity

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22
Q

What are the extrinsic eye muscles?

A
  • superior and inferior rectus
  • lateral and medial rectus
  • superior and inferior oblique
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23
Q

ANATOMY OF THE EYE

A

ANATOMY OF THE EYE

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24
Q

What are the 3 main layers of the eye?

A
  • fibrous outer layer
  • vascular middle layer (uveal tract)
  • inner layer (retina)
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25
Q

What are the 2 parts of the fibrous outer layer of the eye?

A
  • sclera

- cornea

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26
Q

The sclera is continuous with the ______ and forms an avascular “_____” connective tissue covering of the eye.

A
  • cornea

- white

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27
Q
  • The sclera forms an attachment between the eye and what 3 structures?
  • What is the function of these 3 structures together?
A

Structures

  • palpebral conjuctiva of eye lid to close off eye socket
  • dural sheath of CN2
  • tendons of extraoccular muscles

-These 3 structures effectively hold the eye in place

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28
Q

The cornea is an _________ area that covers the ________ surface of the eye ball.

A
  • avascular

- anterior

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29
Q

What are the 2 main parts of the middle layer of the eye?

A
  • choroid

- ciliary body

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30
Q

The choroid is the layer that contains ___________ providing oxygen and nourishment to the outer layer of the retina.

A

blood vessels

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31
Q

What are the 3 parts of the ciliary body?

A
  • ciliary processes
  • ciliary muscle
  • iris
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32
Q

What are the functions of the ciliary processes?

A
  • produce aqueous humor

- attach to suspensory ligaments which connect to lens

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33
Q
  • The ciliary muscle have CN3 ________ and possible _______ roles.
  • The ciliary muscle is a circular smooth muscle at the base of ciliary processes that changes the shape of the lens by pulling on _____________. This provides visual accommodation for what?
A
  • parasympathetic
  • sympathetic
  • suspensory ligaments
  • near and far vision
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34
Q
  • Contraction of the ciliary muscles causes a ________ tension on the lense resulting in a _________ surface for ______ vision.
  • Relaxation of the ciliary muscles causes a ________ tension on the lense resulting in a _________ surface for ______ vision.
A
  • decreased
  • convex (spherical)
  • near
  • increased
  • flattened
  • far
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35
Q

The iris is the area of eye ______. It contains _______ muscle fibers that change size of opening (______) through which light enters the eye ball.

A
  • color
  • smooth
  • pupil
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36
Q

What are the 2 muscles of the iris and what is their function?

A
  • circular m.- constrict pupil; parasympathetic (CN3)

- radial m.- dilate pupil; sympathetic (carotid plexus/ sup cervical plexus)

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37
Q

What is the inner layer of the eye called?

A

Retina

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38
Q

The retina contains ________ sensor receptor cells and is the beginning of the _____________.

A
  • neuron

- visual pathway

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39
Q

What are the 7 main layers of the retina from outside to inside?

A
  • pigment epithelium
  • photoreceptor layer (rods and cones)
  • outer nuclear layer
  • outer synaptic layer (outer plexiform layer)
  • inner nuclear layer
  • inner synaptic layer
  • ganglion cell layer
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40
Q

The pigment epithelium is the outer layer of the retina next to the ________. It is composed of __________ pigmented epithelial cells.

A
  • choroid

- non-neuronal

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41
Q

The photoreceptor layer of the retina contains both _____ and ______. What are their functions?

A
  • rods- dim light vision produces gray images

- cones- bright light vision produces color images

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42
Q

Are there more rods or cones in the photoreceptor layer?

A

rods= 100m/retina

cones=5m/retina

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43
Q

What is the outer nucleur layer of the retina?

A

soma of the rods and cones

44
Q

The inner nuclear layer is important for what reason?

A

it is the bipolar layer for initial image processing

45
Q
  • The ganglian cell layer has what type of neuronal structure?
  • What forms the optic nerve fibers?
A
  • multipolar, NOT pseudounipolar

- axons of the ganglia cells

46
Q
  • Light travels past inner optic nerve cell layer to _____________/____________.
  • Nerve impulses travel from outer photoreceptor layer to ________________.
A
  • outer pigment epithelium/ photoreceptor layer

- inner optic nerve fiber layer

47
Q

What are 3 specialized areas of the retina?

A
  • optic disc
  • macula lutea
  • ora serrata
48
Q

What is the optic disc?

A
  • blind spot; no rods/cones

- area where nerve fibers and blood vessels enter/exit the eye

49
Q

The macula lutea is the ______=________ and contains the _____________ which is an area of only cones and serves as the area of highest visual resolution.

A
  • visual axis=focal point

- central fovea

50
Q

The ora serrata is the _______ margin of the neural (photoreceptor) retina.

A

-anterior

51
Q
  • The lens is connected by ______________ to the ciliary ______/__________.
  • What is the function of the lens?
A
  • suspensory ligaments
  • processes/muscles

-bend light to focus image on retina

52
Q

The vitreous body (humor) is located between what structures and has what function? It also contains phagocytes which do what?

A
  • between lens and retina
  • holds retina in place
  • remove floating debris
53
Q

The anterior cavity (chamber) is located between the _______ and ______. It also contains __________ which is filtered blood plasma secreted by the __________ and drained by the canal of __________ into the venous system in the anterior chamber.

A
  • cornea and lens
  • aqueous humor
  • ciliary body
  • Schlemn
54
Q

LIGHT TRANSDUCTION TO NERVE IMPULSE

A

LIGHT TRANSDUCTION TO NERVE IMPULSE

55
Q

What are the 3 main processes in light transduction?

A
  • Refraction
  • Accomodation
  • Convergence
56
Q

In light refraction, the _______ and ______ bend light rays to focus them on the retina; images are inverted _________ and reversed _______. The ________ lobe corrects retinal images.

A
  • cornea and lens
  • upside down, right to left
  • occipital
57
Q

What is accommodation?

A

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

58
Q
  • In accommodation, for near objects the curvature becomes ______ and ciliary muscles __________ (CN3 parasympathetic stim).
  • In accommodation, for far objects the curvature becomes ______ and ciliary muscles __________ (mostly CN3 parasympathetic inhib).
A
  • greater, contract

- flattened, relax

59
Q

What are 3 dysfunctions in accomodation?

A
  • myopia (nearsightedness)
  • hypermetropia (farsightedness)
  • presbyopia
60
Q

With myopia, the distant objects cannot be seen clearly because the image is focused ________ the retina.

A

in front of

61
Q

With hypermetropia, the near objects cannot be seen clearly because the image is focused _________ the retina.

A

behind

62
Q

What is presbyopia?

A

Lens becomes less elastic with age and therefore less convex moving the focal point for near vision further away from the eyes.

63
Q

What is convergence?

A

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

64
Q

Convergence is necessary to maintain proper overlap in the visual fields of both eyes for _______________ which allows depth perception and three dimensional perception.

A

-binocular vision

65
Q

What are the 8 steps for the light pathway?

A
  1. ) Light
  2. ) Object
  3. ) Reflected light
  4. ) Cornea
  5. ) Aqueous humor
  6. ) Lens
  7. ) Vitrous body
  8. ) Retina
    • pigment cells absorb light
    • photoreceptor cells transduce light to nerve impulses
66
Q

Change pattern of depolarization/hyperpolarization=excitation/inhibition of neuron layers within the retina to change pattern of signals on ______________/CN2.

A

ganglion cell axons

67
Q

VISUAL PATHWAY

A

VISUAL PATHWAY

68
Q

Excitatory and inhibitory impulses generated in ___________ cells move through neurons of other retinal cell layers, where the signal is processed and modified by convergence and divergence, and APs are generated in ____________.

A
  • photoreceptor

- ganglion cells

69
Q

APs exit the eye by what structure?

A

Optic nerve/CN2

70
Q

The optic nerve goes to what structure?

A

-optic chiasm

71
Q
  • At the optic chiasm, impulses from the _____ half of the retina cross over to the opposite side of the brain.
  • At the optic chiasm, impulses from the ________ half of the retina stay on the same side of the brain (ipsilateral)
A
  • nasal

- temporal

72
Q

When are optic tracts formed?

A

after the optic chiasma

73
Q
  • Right visual field=_____ temporal and _____ nasal retina go to the left brain via ____ optic tract
  • Left visual field=_____ temporal and ____ nasal retina go to the right brain via _____optic tract
A
  • left, right, left

- right, left, right

74
Q

The optic tracts send signals to what 3 areas?

A
  • pretectal area- pupillary reflex
  • superior colliculus- tracing eye movements and head turning
  • lateral geniculate nucleus of thalamus
75
Q

Spacial relationships of the visual/retinal fields are maintained in the ________________.

A

lateral geniculate nucleus

76
Q

From the thalamus impulses move on the _______________ to the visual cotex locates in the _________ lobes.

A
  • optic radiations

- medial occipital lobes

77
Q

EXTERNAL EYE MUSCLES

A

EXTERNAL EYE MUSCLES

78
Q

The external eye muscles originate on the _________ bone and insert on the ________.

A
  • orbital

- sclera

79
Q

What are the 8 external eye muscles and what nerve innervates them?

A
  • Levator palpebrae superioris (CN3)
  • Orbicularis oculi (CN7)
  • Superior oblique (CN4)
  • Inferior oblique (CN3)
  • Superior rectus (CN3)
  • Inferior rectus (CN3)
  • Medial rectus (CN3)
  • Lateral rectus (CN6)
80
Q

What is the function of the Levator palpebrae superioris?

A

elevate eye lid=open

81
Q

What is the function of the Orbicularis oculi ?

A

depress eye lid=close

82
Q

What is the function of the Superior oblique?

A
  • from near focus (eyes adducted) will further adduct=clinically relevant
  • from far focus (eyes abducted) will further abduct=anatomically relevant
  • will also depress & medially rotate
83
Q

What is the function of the Inferior oblique?

A
  • from near focus (eyes adducted) will further adduct=clinically relevant
  • from far focus (eyes abducted) will further abduct=anatomically relevant
  • will also elevate and laterally rotate
84
Q

What is the function of the Superior rectus?

A

elevate (slight adduct and med. rotate)

85
Q

What is the function of the Inferior rectus?

A

depress (slight adduct and lat. rotate)

86
Q

What is the function of the Medial rectus?

A

adduct

87
Q

What is the function of the Lateral rectus?

A

abduct

88
Q

PATHWAYS OF CN3,4,6 AND SYMPATHETICS

A

PATHWAYS OF CN3,4,6 AND SYMPATHETICS

89
Q

CN3 is what nerve?

A

occulomotor

90
Q

CN3 (occulomotor) has both ______motor and _______motor neurons.

A
  • somato

- viscero

91
Q

What is the general pathway of CN3?

A
  • nuclei (somatomotor nuc= occulomotor nuc; parasympathetic nuc= Edinger Westphal nucleus)
  • cranial cavity foramen= superior orbital fissure
  • superior or inferior division to ipsilateral=uncrossed
92
Q
  • The nuclei of CN3 are locates at the level of the _________.
  • What are the 2 nuclei involved in the pathway?
A

-brainstem

  • somatomotor nucleus= occulomotor nucleus
  • parasympathetic nucleus= Edinger-Westphal nucleus
93
Q

The cranial cavity foramen is also known as what?

A

superior orbital fissure

94
Q

The superior division goes to the _______ side and contains what muscles?

A

-ipsilateral

  • superior rectus
  • levator palpebrae
95
Q

The inferior division goes to the ________ side and contains what muscles?

A

-ipsilateral

  • inferior rectus
  • medial rectus
  • inferior oblique
  • ciliary ganglion including ciliary body/muscles and circular muscles of iris
96
Q

CN4 is what nerve?

A

trochlear

97
Q

CN4 neurons are _________ to eye muscles as well as ___________ proprioception.

A
  • somatomotor

- somatosensory

98
Q

What is the pathway of CN4?

A
  • nucleus at midbrain
  • cross pre-tectum
  • cranial foramen= superior orbital fissure
  • contralateral superior oblique muscle
99
Q

CN6 is what nerve?

A

abducent

100
Q

CN6 neurons are ________ to lateral rectus muscle?

A

-somatomotor

101
Q

What is the pathway of CN6?

A
  • nucleus at open medulla
  • superior orbital fissure
  • ipsilateral lateral rectus muscle
102
Q

What is the pathway of sympathetic neurons?

A
  • preganglionic neuron lateral horn T1
  • postganglionic neuron in superior cervical ganglia of paravertebral chain ganglia
  • carotid/sympathetic plexus of nerves
  • head structures: iris, glands
103
Q

REFLEXES

A

REFLEXES

104
Q

What is the pathway of pupillary light reflex?

A
  • light
  • ganglion cells
  • optic n/ optic tract
  • pre-tectal area
  • Edinger-Westphal nucleus on both sides (bilateral projection via posterior commissure)
  • parasympathetic preganglionic
  • ciliary ganglia
  • parasympathetic postganglionic
  • contract circular m. of iris
  • pupil constricts (direct pupillary light reflex, consensual pupillary light reflex)
105
Q

What is the difference between direct and consensual pupillary light reflex?

A
  • direct pupillary reflex is pupillary response to light that enters the ipsilateral (same) eye
  • consensual pupillary reflex is response of a pupil to light that enters the contralateral (opposite) eye
106
Q

What is the accomodation reflex pathway?

A
  • changes from far to near objects
    1. )motor cortex→CN3→medial rectus muscles both sides→adduct to facilitate convergence of visual field
    2. )papillary constriction reflex→pupillary constriction
    3. )activate Edinger-Westphal→ciliary ganglia→ciliary m. contract→↑curvature lens→near vision

Neuroanatomy and Physiology (19 decks)

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