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Neuromotor Function 1 > Lecture 14 - Special Sensory Systems > Flashcards

Lecture 14 - Special Sensory Systems Flashcards

1
Q

Describe how an image is formed on the retina.

A

Inverted and reversed

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2
Q

Describe the visual representation on the retina.

A

Temporal visual field is projected on to the nasal retinal area.
Nasal visual field is projected on to the temporal retinal area.

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3
Q

Define what it means by visual field.

A

It is the total amount of space that can be viewed by the retina when the eye is fixated straight ahead

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4
Q

T/F: When testing for visual field deficits you always test both eyes at the same time.

A

False (one eye at a time)

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5
Q

What are the 3 components of the retina.

A
  1. Photoreceptors
  2. Fovea
  3. Optic Disc
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6
Q

What are the 2 types of photoreceptors found on the retina?

A
  1. Cons

2. Rods

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7
Q

What is the significance of the fovea?

A

The place where the receptors are in the highest density and are very sensitive - also means that if the image falls on fovea it will be the sharpest.

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8
Q

What is the significance of the optic disc?

A

A part of the retina where there are no receptors - it’s a natural blind spot on retina.

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9
Q

Trace the path of light coming into the eye starting at the photoreceptors and ending at the optic nerve.

A

Light -> photoreceptors -> bipolar neurons -> ganglion cells -> optic nerve cells

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10
Q

What type of cells form the optic nerve?

A

ganglion cells

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11
Q

At what structure do the two optic nerves unite? Where on the midbrain is this?

A

optic chiasm

anterior midbrain

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12
Q

T/F: All the fibers of the optic nerve cross.

A

False

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13
Q

The fibers from the ______ half of each retina cross midline and enter optic tract of ____ side.

A

median (nasal);

opposite

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14
Q

The fibers from the _______ half of each retina pass posteriorly in optic tract of ____ side.

A

lateral (temporal);

same

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15
Q

The optic ____ wraps around the midbrain.

A

Tract

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16
Q

Where do fibers of the optic tract terminate.

A

lateral geniculate nucleus of the thalamus

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17
Q

How does visual info get from the thalamus to the primary visual cortex in the occipital lobe?

A

Axons project posteriorly from the thalamus in the form of optic radiations to the primary visual cortex.

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18
Q

Which 2 arteries supply the optic radiation.

A

deep branches of middle cerebral artery and posterior cerebral artery

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19
Q

How many times does the visual information cross?

A

1 - at the optic chiasm

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20
Q

The primary visual cortex is located on the border of which fissure?

A

superior and inferior borders of the calcarine fissure

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21
Q

How does visual info processing occur at the primary visual cortex?

A

First part of the processing occurs posteriorly in the cortex and the info moves anteriorly for additional processing

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22
Q

Interpretation of visual signals occurs where?

A

Visual association cortex

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23
Q

Differentiate between the WHERE and the WHAT pathway.

A

Where pathway: finds where the object is within the visual field
What pathway: analyzes what the visual image actually is

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24
Q

Name the two additional pathways taken by visual information.

A

Some pathways bypass the lateral geniculate nucleus and project onto:

  1. Superior colliculus
  2. Pretectal nucleus
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25
Q

What is the role of the superior colliculus in relation to vision?

A

Uses the tectospinal tract to coordinate head and eye movements

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26
Q

What does the pretectal nucleus do in terms of vision? Outline the pathway it uses.

A

Responsible for the pupilary light reflex.
Pretectal neucleus in midbrain -> parasympathetic neurons in occulomotor N nucleus -> parasympathetic fibers in occulomotor N -> for pupil constriction

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27
Q

T/F: The left visual field is processed by the left hemisphere.

A

False (right hemisphere)

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28
Q

How would vision be affected if the left optic nerve is severed?

A

total loss of vision from left eye

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29
Q

How would vision be affected if there was partial damage to the left optic nerve?

A

information from nasal visual field of left eye (temporal part of left retina) is lost

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30
Q

What kind of damage would lead to loss of the temporal portions of the visual field? What is this called?

A

Severing of crossing fibers of the nasal part of the retina (at the optic chiasm)
Bitemporal hemianopia

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31
Q

A lesion in left optic tract OR pathway from lateral geniculate nucleus to cortex OR optic radiation would result in what kind of vision loss? What is this called?

A

loss of vision of the right side from both eyes

Contralateral homonymous hemianopia

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32
Q

List the 5 types of eye movements.

A
  1. Saccadic eye movements
  2. Smooth pursuit eye movements
  3. Nystagmus
  4. Vergence eye movements
  5. Reflex eye movements
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33
Q

Describe saccadic eye movements.

A
  • rapid, ballistic movements of both eyes in the same direction
  • made spontaneously in response to a suddenly appearing (or jumping) object
  • produced while we scan a visual scene or read
34
Q

T/F: Saccadic eye movements are always voluntary.

A

False (can be involuntary too)

35
Q

Describe smooth pursuit eye movements.

A

slower eye movements to track or follow a moving object

•occur automatically in presence of moving target

36
Q

Describe nystagmus eye movements.

A

Involuntary eye movement characterized by alternating smooth pursuit in one direction and saccadic movement in the other direction.

37
Q

You would test ________ eye movements all the time, especially in people with cerebellar deficits.

A

nystagmus

38
Q

Describe vergence eye movements.

A

To maintain foveation/fixation by both eyes as targets move toward or away from viewer

39
Q

Describe reflex eye movements.

A
  • Stabilize the eyes relative to the external world

* Compensate for head movements

40
Q

The ____ -_____ reflex allows for reflex eye movements.

A

vestibulo-ocular

41
Q

What are the two ocular muscles allowing for horizontal control of the eye?

A

medial and lateral rectus muscles

42
Q

How does the medial longitudinal fasciculus allow for horizontal eye movement?

A

It coordinates the actions of the two cranial nerves that are responsible for the medial and lateral rectus muscles. It also forms a connection between the cranial nerve nuclei of eye muscles and superior vestibular nuclei.

43
Q

What is the function of the paramedian pontine reticular formation?

A

It provides input from the cortex and other pathways to the abducens nucleus. Especially important for lateral horizontal gaze.

44
Q

What is the term for a lesion at the medial longitudinal fasciculus?

A

Internuclear Ophthalmoplegia (INO)

45
Q

** Brain Break**

What did the policeman say to his belly button?

A

“You’re under a vest!”

46
Q

An INO interrupts input to the ____ rectus. The eye that is ______ to the lesion will not ____ fully when trying to look to the side.

A

medial
ipsilateral
adduct

47
Q

T/F: There are descending pathways from cerebral cortex travel to brainstem neuclei to control eye movements

A

True

48
Q

What are the 3 cortical areas controlling eye movements?

A

frontal eye fields
parieto-occipito-temporal cortex
primary visual cortex and visual association cortex

49
Q

The external auditory ear canal is called ______.

The ear drum is called ______.

A

meatus

tympanic membrane

50
Q

The 3 bones in the ear are called ______, ______, and _____ and are located in the ________ ear.

A

malleus, incus, stapes

middle

51
Q

What moves the fluid in the chamber of the cochlea?

A

The stapes vibrating against the oval window of the cochlea.

52
Q

T/F: The cochlea is located in the middle ear.

A

False (inner ear - labyrinth)

53
Q

List the 2 regions (and their functions) of the labyrinth.

A
  1. vestibular apparatus - equilibrium

2. cochlea - hearing

54
Q

The receptors for sound are hair cells, which are a form of ______receptor. The hair cells are in the ______ membrane in the _____ compartment of the cochlear duct.

A

mechano
basilar
middle

55
Q

What causes depolarization of the hair cells? Which nerve transmits this information?

A

bending of hair cells;

cochlear division of Vestibulocochlear cranial nerve

56
Q

T/F: Hair cells are deferentially sensitive to different frequencies.

A

True

57
Q

High frequency sounds are detected by hair cells near the ____ ____ while low frequency sounds are detected by hair cells farther down the length of the ____ duct.

A

oval window;

cochlear

58
Q

Trace the path that the auditory information takes starting with the depolarization of hair cells and ending at the primary auditory cortex.

A

depolarization of hair cells -> CN 8 (Vestibulocochlear nerve - cochlear division) -> cochlear nuclei in rostral medulla -> ascend bilaterally through lateral leminiscus -> inferior colliculi ->inferior brachium ->medial geniculate nuclei of thalamus -> primary auditory cortex.

59
Q

T/F: Auditory info ascends unilaterally from brainstem.

A

False (bilaterally)

60
Q

List the 3 main functions of the vestibular system.

A
  1. regulation of posture and muscle tone
  2. coordination of eye and head movements
  3. conscious perception of spatial orientation
61
Q

The vestibular system is part of the _____ ear.

A

inner

62
Q

What are the names of the two static labyrinth/otolith organs?

A

utricle and saccule

63
Q

What are the roles of the utricle and saccule?

A
  1. detect linear acceleration

2. head orientation in relation of gravity

64
Q

The specialized epithelial lining located within both saccule and utricle is called the _______.

A

macula

65
Q

What are the 3 components of the macula?

A
  1. calcified crystals – Otoconia
  2. gelatinous layer
  3. hair cells
66
Q

How do the hair cells in the macula get activated?

A

Changes in head position pull on the otoconia which in turn activates the hair cells.

67
Q

Once depolarization of the hair cells occur in the static labyrinth, it sends the info via CN 8 to the _____ nuclei. about _______ acceleration.

A

Vestibular;

linear

68
Q

What is Scarpa’s ganglia?

A

A collection of the cell bodies of the primary sensory neurons; located in the vestibular ganglia.

69
Q

Static labyrinth conveys info about _____ acceleration while kinetic labyrinth conveys info about ______ acceleration.

A

linear;

angular

70
Q

The kinetic labyrinth is composed of the semicircular canals which are ____ labyrinths in the _____ bone containing _______ fluid.

A

bony;
temporal;
perilymph

71
Q

The ________ labyrinth is in the bony labyrinth and contain ____ fluid.

A

membranous;

endolymph

72
Q

Define and ampulla.

A

The swelling on one end of each semicircular canal.

73
Q

What structure, which contains hair cells is found in the ampulla?

A

cupula

74
Q

What process lets you know that you’re moving your head?

A

Endolymph moves with head movement and as it flows it bends and excites the hair cells. (HINT: think seaweed)

75
Q

Describe how the information pathway between the static and kinetic labyrinths are similar.

A

For both kinetic and static:

  1. primary sensory neurons are excited (cell bodies in Scarpa’s ganglia)
  2. info travels from the semicircular canals -> CN 8 -> vestibular nuclei
76
Q

List and describe the two tracts found in the vestibular nuclei.

A 
Lateral vestibulospinal tract:
•descends through length of spinal cord
•facilitates activity of extensor muscles to maintain balance
Medial vestibulospinal tract:
•descends to cervical spinal cord
•for controlling neck and head position
77
Q

The ascending pathways from vestibular nuclei travel to what 3 areas of the brain?

A
  1. thalamus
  2. primary vestibular cortex
  3. posterior insula
78
Q

Why are connections (via some neurons in Scarpa’s ganglia) with the cerebellum important?

A

They regulate balance and eye movement

79
Q

Benign paroxysmal positional vertigo, the most common cause of vertigo, is caused by ______ in the semicircular canals, almost always in _____ canal

A 
loose debris (mainly otoconia);
posterior
80
Q

What are some symptoms and causes of benign paroxysmal positional vertigo.

A

Symptoms: room spinning (NOT head spinning)
Causes: sudden deceleration of the head (whiplash, sports collision, fall)

Neuromotor Function 1 (21 decks)

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