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501 Neuro > Visual System > Flashcards

Visual System Flashcards

1
Q

What is the fovea?

A

Small depression in the eye socket where visual acuity is the highest

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2
Q

Why does the fovea have high visual acuity?

A

Contains mostly cones
The displacement of retinal layers in the middle allow for more light to reach the photoreceptors

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3
Q

Light travels from ____ to ____ through the retina

A

Anterior to posterior

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4
Q

The external nuclear layer of the retina contains

A

Cell bodies of photoreceptors

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5
Q

The internal nuclear layer of the retina contains

A

Cell bodies of bipolar neurons, horizontal cells, amacrine cells, Muller supporting cells

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6
Q

The third group of cells in the retina is called the …. and contains ….

A

Retinal ganglion neurons
Cell bodies of these ganglia

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7
Q

What are the 3 groups of cells in the retina going anterior to posterior?

A

Retinal ganglion neurons
Internal nuclear layer
External nuclear layer

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8
Q

Retinal detachment occurs between layers __ and ___

A

1 and 2

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9
Q

Rods are responsible for

A

Vision in light of low intensity
Predominate in periphery of retina
Responsible for sensing something in the dark

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10
Q

Cones are responsible for

A

Visual acuity and color vision
Concentrated at fovea
Move eyes so fovea gets input

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11
Q

What is phototransduction?

A

Conversion of light into electrical signals

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12
Q

The visual pathway consists of

A

Photoreceptors
Bipolar neurons
Retinal ganglion neurons
LGN (lateral geniculate nucleus) of the thalamus
Primary visual cortex

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13
Q

Where does more complicated visual processing occur?

A

Downstream of the primary visual cortex

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14
Q

The retrolenticular limb of the internal capsule contains axons from ___ that lead to _____

A

From LGN (lateral geniculate nucleus)
Leads to primary visual cortex

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15
Q

What is the optic radiation?

A

LGN neurons that project from thalamus to primary visual cortex
Neurons go through retrolenticualr limb of the internal capsule to become the optic radiation

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16
Q

The lateral inferior optic radiation is also referred to as … goes through …

A

Called Meyer’s loop
Goes through temporal lobe to inferior back of calcarine sulcus (lingual gyrus)

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17
Q

The medial super optic radiation goes through

A

Parietal lobes to superior bank of calcarine sulcus (cuneus gyrus)

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18
Q

Peripheral retina information goes to which part of the primary visual cortex?

A

Anterior

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19
Q

Fovea information goes to which part of the primary visual cortex?

A

Posterior

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20
Q

What is the cuneus?

A

Superior part of the occipital lobe

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21
Q

What is the lingual gyrus?

A

Inferior portion of the occipital lobe

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22
Q

What are other targets of retinal ganglion neurons?

A

Superior chiasmatic nucleus of hypothalamus for diurnal rhythms (day length)
Pretectal area: pupillary light reflex
Superior colliculus: eye movements

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23
Q

The retina and optic nerve are provided blood supply from

A

Opthalmic artery of internal carotid artery

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24
Q

The optic chiasm receives blood supply from?

A

ACA and anterior communicating artery

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25
Q

The optic tract receives blood supply from?

A

Anterior choroidal artery of internal carotid artery

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26
Q

The LGN (lateral geniculate nucleus) receives blood supply from?

A

Thalamogeniculate artery of PCA

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27
Q

The lateral inferior optic radiation (Meyer’s loop) receives blood supply from?

A

MCA

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28
Q

The medial superior optic radiation receives blood supply from?

A

PCA

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29
Q

The primary visual cortex receives blood supply from?

A

Calcarine artery of PCA

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30
Q

The dorsal stream of the visual association cortex provides information about

A

Where
Location of stimulus and movement direction

31
Q

The ventral stream of the visual association cortex provides information about

A

What
Form (shape) and color perception

32
Q

The dorsal stream primarily contains …. and sends information to ….

A

Contains rods
Sends information to anterior primary visual cortex and dorsal association visual cortices

33
Q

The ventral stream primarily contains ….. and sends information to …..

A

Contains cones
Sends information to posterior primary visual cortex and ventral association visual cortical areas

34
Q

What happens with damage to the dorsal stream?

A

Patient can still identify objects but cannot tell which is closest to each other

35
Q

The four quadrants of the visual field are made up of

A

Nasal (medial) and temporal (lateral) halves

36
Q

The visual field is ___ and ____ on retina

A

Reversed and inverted

37
Q

Retinal ganglion neurons from the nasal (medial) half of retina cross at the …
Those from temporal (lateral) half of the retina ….

A

Optic Chiasm
Do not cross

38
Q

Retinal ganglion neurons transmitting information about an object located in one half of the visual field ends up in ___ tract

A

Contralateral

39
Q

What is an anopia?

A

Visual field cut

40
Q

What is hemianopia?

A

Loss of one half of the visual field

41
Q

What is quadrantanopia?

A

Loss of one quarter of the visual field

42
Q

What does it mean if the anopia is homonymous?

A

Deficit in the same half or quadrant of the visual field for each eye

43
Q

What does it mean if the anopia is heteronymous?

A

Deficit is in the different half or quadrant of the visual field for each eye

44
Q

Ipsilateral blindness occurs when there is destruction to …

A

Optic nerve or retina
Blindness is paired with loss of pupillary light reflex

45
Q

Bitemporal (lateral) hemianopia occurs with

A

Destruction of crossing axons at the optic chiasm
Also called tunnel vision
Person cannot see laterally

46
Q

Right hemianopia (half) occurs with

A

Destruction of lateral aspect of optic chiasm (usually due to aneurysm of internal carotid artery)
Also called nasal hemianopia (medial)

47
Q

Right homonymous hemianopia occurs with

A

Destruction of optic tract, LGN, optic radiation, or primary visual cortex
Also called contralateral homonymous hemianopia
Lose visual field on the right in both eyes

48
Q

What is macular sparing?

A

Loss of right side of visual field as well as around the pupil
Occurs due to occlusion of calcarine artery

49
Q

What is left superior quadrantanopia?

A

Loss of left upper quadrant on both sides
Due to damage at Meyer’s loop
Also called contralateral superior quadrantanopia

50
Q

What happens with direct light reflex?

A

Pupil constricts in eye stimulated by light

51
Q

What happens with consensual light reflex?

A

Pupil constricts in contralateral eye

52
Q

What is the order of pupillary light reflex synapsing?

A

Retinal ganglion neurons > pretectal neurons (afferent lim) > Edinger-Westphal nuclei (parasympathetic) > ciliary ganglion (efferent limb) > pupillary sphincter muscle and causes contraction

53
Q

Pupillary dilation reflex: Hypothalamic neurons synapse at

A

T1 to T3 of spinal cord

54
Q

Pupillary dilation reflex: Sympathetic preganglionic neurons synapse in

A

Superior cervical region

55
Q

Pupillary dilation reflex: sympathetic postganglionic neurons synapse on

A

Pupillary dilator muscle and cause contraction

56
Q

What are the 3 ways that eyes accommodate and maintain a clear visual image as gaze shifts from distant to near point?

A
  1. 2 eyes converge to midline from contraction of medial rectus muscles
  2. constriction in pupil from pupillary sphincter muscles
  3. Lens thickens due to contraction of ciliary muscles from ciliary ganglia
57
Q

What are extraocular muscles and cranial nerves associated?

A

CN III: oculomotor nerve, superior rectus, inferior rectus, medial rectus, inferior oblique muscle
CN IV: trochlear nerve, superior oblique muscle
CN VI: abducens, lateral rectus muscle

58
Q

What muscles are involved in horizontal eye movements?

A

Lateral rectus (CN VI) abducts the eye
Medical rectus (CN III) adducts the eye

59
Q

What are conjugate eye movements?

A

Both eyes move in the same direction

60
Q

What are vergent eye movements?

A

Eyes move in opposite directions

61
Q

What is the horizontal gaze center?

A

PPRF, paramedian pontine reticular formation

62
Q

What is the frontal eye field center?

A

Frontal lobe

63
Q

There is an eye field in ___ lobes

A

All lobes

64
Q

What is the pathway for voluntary horizontal gaze to the right?

A

Activate left frontal eye field
Right PPRF excited
Righ abducens nucleus excited
Internuclear neurons (MLF)
Left oculomotor nucleus excited (MLF)

65
Q

What muscles contract with horizontal gaze to the right? This leads to ….

A

Right lateral rectus muscle
Medial rectus muscle
Both eye gazes right

66
Q

What eye fields are responsible for saccades?

A

Frontal eye fields
Shifting gaze from one stationary object to another

67
Q

What eye fields are responsible for smooth pursuit?

A

Multiple
Done to track a moving object

68
Q

The cerebral eye fields are supplied by the

A

MCA

69
Q

The midbrain structures are supplied by

A

PCA

70
Q

The pontine structures are supplied by

A

Basilar artery

71
Q

Lesion to the left frontal eye field leads to

A

Transient (temporary) paralysis of gaze to right
It is temporary due to redundant connections, bilateral cortical connections to brainstem gaze centers

72
Q

Lesion to right PPRF (paramedian pontine reticular formation) leads to

A

Paralysis of gaze to the right
Permanent loss due to no redudancy

73
Q

Lesion to left MLF (medial longitudinal fasciculus) leads to

A

Paralysis of gaze to right of left eye only
Right eye not affected because the pathway to the lateral rectus is intact
Also called left internuclear ophthalmoplegia

74
Q

Lesion to the right abducens nerve leads to

A

Paralysis of gaze to right of right eye only

501 Neuro (16 decks)

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