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Neuroscience & Mental Health Y2 > Neurology of the Visual System > Flashcards

Neurology of the Visual System Flashcards

1
Q

7 landmarks of the visual pathway?

A
  • Eye
  • Optic nerve- Ganglion nerve fibres
  • Optic chiasm- Half of the nerve fibres cross here
  • Optic tract- Ganglion nerve fibres exit as the optic tract
  • Lateral Geniculate Nucleus- Ganglion nerve fibres synapse here
  • Optic Radiation- 4th order neuron
  • Primary Visual Cortex or Striate Cortex- within the occipital lobe
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2
Q

1st order neurons of the retina?

A

rod and cone photoreceptors

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3
Q

2nd order neurons of the retina?

A

retinal bipolar cells

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4
Q

3rd order neurons of the retina?

A

retinal ganglion cells

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5
Q

afferent innervation of the retina is via the …

A

optic nerve

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6
Q

Partial decussation of the optic nerve occurs in the …

A

optic chasm

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7
Q

Destination of the optic nerve/

A

Lateral geniculate nucleus

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8
Q

What is the receptive field of a neuron

A

a retinal space within which incoming light can alter the firing pattern of a neuron

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9
Q

In a retinal ganglion cell there is a convergence of XX from YY

A

receptive fields

neighbouring photoreceptors

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10
Q

Cone system divergence is [more/less] than rod system convergence

A

Less

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11
Q
  • Central retina convergence is [more/less] than peripheral retina convergence
A

Less

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12
Q

Low convergence:
receptive field size?
Visual acuity level?
Light sensitivity?

A

Small receptive field, fine visual acuity, low light sensitivity

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13
Q

High convergence:
receptive field size?
Visual acuity level?
Light sensitivity?

A

Large receptive field, coarse visual acuity, high light sensitivity

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14
Q

What cell is between the rod/cone photoreceptor and the retinal ganglion cell

A

retinal Bipolar cells

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15
Q

ON-centre ganglions are stimulated by and inhibited by light where?

A
  • Stimulated by light at the centre of the receptive field

- Inhibited by light on the edge of the receptive field

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16
Q

OFF-centre ganglions are stimulated by and inhibited by light where?

A
  • Inhibited by light at the centre of the receptive field

- Stimulated by light on the edge of the receptive field

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17
Q

What are on and off centre ganglion cells important for

A

contrast sensitivity and enhanced edge detection

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18
Q

Fibres that cross in the optic chiasm originate in the X retina and correspond to the Y visual field

A

nasal

temporal

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19
Q

LESION AT OPTIC CHIASMA causes…

A

BITEMPORAL HEMIANOPIA

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20
Q

LESION posterior to the OPTIC CHIASMA causes…

A
  • Right sided lesion- left homonymous hemianopia in both eyes
  • Left sided lesion- right homonymous hemianopia in both eyes
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21
Q

7 types of visual field defects

A 
monocular blindness
bitemporal hemianopia
right/left nasal hemianopia
right/left homonymous hemianopia
TR/TL/BR/BL quadrant-anoxia
Macular sparing homonymous hemianopia
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22
Q

Cause of bitemporal hemianopia

A

pituitary gland tumour

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23
Q

Cause of bitemporal hemianopia

A

stroke

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24
Q

Primary visual cortex is located along the …

A

calcarine sulcus within occipital lobe

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25
Q

Primary visual cortex is characterised by….

A

a distinct stripe derived from the myelinated fibre of optic radiation projecting onto the visual cortex

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26
Q

Where are the superior/inferior/right/left visual fields found

A
  • Superior visual field projects to below Calcarine fissure
  • Inferior visual field projects to above Calcarine fissure
  • Right hemifield from both eyes projects to left primary visual cortex
  • Left hemifield from both eyes projects to right primary visual cortex
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27
Q

How is the primary visual cortex organised and what are they sensitive to

A
  • Organised as columns with unique sensitivity to visual stimulus of a particular orientation
  • Right and left eye dominant columns alternate
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28
Q

what causes MACULAR SPARING HOMONYMOUS HEMIANOPIA

A

Damage to primary visual cortex:

- Often due to stroke

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29
Q

MACULAR SPARING HOMONYMOUS HEMIANOPIA leads to…

A

contralateral homonymous hemianopia with macula sparing

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30
Q

Why is the macula spared in MACULAR SPARING HOMONYMOUS HEMIANOPIA

A
  • Area representing macula in the primary visual cortex receives dual blood supply from posterior cerebral arteries from both sides so it is spared
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31
Q

Where is the EXTRASTRIATE CORTEX

A

around primary visual cortex within occipital lobe

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32
Q

What does the EXTRASTRIATE CORTEX do

A

Converts basic info, orientation and position into complex information

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33
Q

2 pathways of the extra striate cortex?

A

DORSAL pathway

VENTRAL pathway

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34
Q

What is the dorsal pathway of the extra striate cortex

A
  • Primary visual cortex -> Posterior parietal visual cortex
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35
Q

What is the ventral pathway of the extra striate cortex

A
  • Primary visual cortex -> Inferiotemporal visual cortex
36
Q

What is the ventral pathway of the extra striate cortex responsible for (2)

A
  • Motion detection

- Visually-guided action

37
Q

Visual cortex is also known as the…

A

striate cortex

38
Q

What is the ventral pathway of the extra striate cortex responsible for (4)

A
  • Object representation
    face recognition
  • Detailed fine central vision
    colour vision
39
Q

Damage to the dorsal visual pathway results in…

A

motion blindness

40
Q

Damage to the ventral visual pathway results in…

A

Cerebral achromatopsia

41
Q

What nerve mediates pupil constriction

A

Optic

42
Q

Pupil constriction - [increases/decreases] depth of field

A

Increases

43
Q

Afferent pathway of the pupillary reflex? (4)

A
  • Rod and cone receptors synapsing on bipolar cells which synapse on retinal ganglion cells
  • Pupil-specific ganglion cell exits at posterior third of optic tract before entering LGN
  • Synapses at brainstem (pretectal nucleus)
  • Afferent pathway from each eye synapses on EDINGER-WESTPHAL nuclei on both sides of the brainstem
44
Q

Efferent pathway of the pupillary reflex? (4)

A
  • Edinger-westphal nucleus  Oculomotor nerve efferent
  • Synapses at ciliary ganglion
  • Short posterior ciliary nerve  Pupillary sphincter
45
Q

DIRECT light reflex is…

A

Constriction of pupil of the light-stimulated eye

46
Q

CONSENSUAL light reflex is…

A

Constriction of pupil of the fellow (other) eye

47
Q

Neurological basis of consensual light reflex?

A

afferent pathway on either side alone will stimulate efferent pathway on both sides

48
Q

What is the result of a torch test on an eye with:

RIGHT AFFERENT defect

A

e.g. damage to optic nerve)- no pupil constriction on both eyes when right eye is stimulated with light but normal pupil constriction of both pupils when left eye is stimulated with light

49
Q

What is the result of a torch test on an eye with:

RIGHT EFFERENT defect

A

(e.g. damage to right 3rd nerve)- no right pupil constriction whether right or left eye stimulated with light but left pupil constricts whether right or left eye stimulated with light

50
Q

What is the result of a torch test on an eye with:

UNILATERAL AFFERENT defect

A

Difference in response depending on which eye is stimulated

51
Q

What is the result of a torch test on an eye with:

UNILATERAL EFFERENT defect

A

Same unequal response between left and right eye irrespective of which eye is stimulated

52
Q

How many extraocular muscles

A

6

53
Q

DUCTION means?

A

Movement in one eye

54
Q

VERSION means?

A

Simultaneous movement of both eyes in same direction

55
Q

VERGENCE means?

A

Simultaneous movement of both eyes in the opposite direction

56
Q

CONVERGENCE means?

A

Simultaneous adduction (inwards) movement in both eyes when viewing a near object

57
Q

What is SACCADE movement

A

Short fast burst (up to 900/sec)

58
Q

What is smooth pursuit movement

A

Sustained slow movement (up to 60/s)

- Driven by motion of a moving target across the retina

59
Q

6 muscles of the eye names?

A 
SUPERIOR RECTUS
INFERIOR RECTUS
LATERAL RECTUS
MEDIAL RECTUS
SUPERIOR OBLIQUE
INFERIOR OBLIQUE
60
Q

Attachment and movement of the eye of the superior rectus?

A

Attached to the eye at 12 o’clock- moves the eye up

61
Q

Attachment and movement of the eye of the inferior rectus?

A

Attached to the eye at 6 o’clock- moves the eye down

62
Q

Attachment and movement of the eye of the lateral rectus?

A

Also called the external rectus, it attaches to the temporal side of the eye and moves the eye outward of the head (toward the temple)

63
Q

Attachment and movement of the eye of the medial rectus?

A

Also called the internal rectus, it attaches to the nasal side of the eye and moves the eye towards the middle of the head (toward the nose

64
Q

Attachment and movement of the eye of the inferior oblique?

A

Attaches high on the temporal side of the eye, passes under the superior rectus and travels through the trochlea- it moves the eye in a diagonal pattern down and in

65
Q

Attachment and movement of the eye of the superior oblique?

A

Attaches low on the nasal side, passes under the inferior rectus and move the eye in a diagonal pattern up and out

66
Q

Innervation of the superior rectus?

A

superior branch of the oculomotor

67
Q

Innervation of the inferior rectus?

A

Inferior branch of the oculomotor

68
Q

Innervation of the medial rectus?

A

Inferior branch of the oculomotor

69
Q

Innervation of the lateral rectus?

A

Abducens

70
Q

Innervation of the superior oblique?

A

Trochlear

71
Q

Innervation of the inferior oblique?

A

Inferior branch of the oculomotor

72
Q

Innervation of the lid elevator?

A

superior branch of the oculomotor

73
Q

Innervation of pupil constriction?

A

Inferior parasympathetic branch of the oculomotor nerve

74
Q

What does the oculomotor nerve innervate? (6)

A 
-	superior branch
Superior rectus
Lid elevator
-	inferior branch
Inferior rectus
Medial rectus
Inferior oblique
Parasympathetic nerve- constricts pupil
75
Q

What does the superior branch of the oculomotor nerve innervate? (2)

A

Superior rectus

Lid elevator

76
Q

What does the inferior branch of the oculomotor nerve innervate? (4)

A

Inferior rectus
Medial rectus
Inferior oblique
Parasympathetic nerve- constricts pupil

77
Q

What does the trochlear nerve innervate? (6)

A

Superior oblique

78
Q

What does the abducens nerve innervate? (6)

A

Lateral rectus

79
Q

What muscle abducts

A

Lateral rectus

80
Q

Difference between -duction and -version

A
  • duction is one eye

- version is two eyes

81
Q

What muscle adducts

A

MEDIAL RECTUS

82
Q

What is 3rd nerve palsy characterised by and what muscles cause the direction. Is there double vision

A
  • Affected eye down and out
  • Droopy eyelid
  • Unopposed superior oblique innervated by 4th nerve (down)
  • Unopposed lateral rectus action innervated by 6th nerve (out)
  • No double vision
83
Q

What is 6th nerve palsy characterised by and what muscles cause the direction. Is there double vision

A
  • Affected eye unable to abduct and deviates inwards

- Double vision worsens when gazing to the side of the affected eye

84
Q
  • Optokinetic nystagmus is…
A

smooth pursuit and fast phase reset saccade

85
Q
  • Presence of ON in response to moving grating signifies that the subject has XXXXXXXX
A

sufficient visual acuity to perceive the grating pattern

Neuroscience & Mental Health Y2 (18 decks)

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