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CNS > Lecture 5 - Retina And Central Visual Pathways > Flashcards

Lecture 5 - Retina And Central Visual Pathways Flashcards

1
Q

What is the outermost tough layer roof the eye?

A

Sclera

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2
Q

What are some components of the retina?

A

Pigmented layer
Photoreceptor cells
Bipolar cells
Horizontal cells

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3
Q

What is the function of the pigmented layer of the retina?

A

Helps absorb excessive light preventing overstimulation of the optic nerve

They anchor photoreceptors

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4
Q

What is an an example of a condition that has problems with the pigmented layer of the retina?

A

Albinism

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5
Q

What are the 2 types of photoreceptor cells?

A

Rods
Cones

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6
Q

What is the function of the rods?

A

Black and white night vision

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7
Q

What is the function of cones?

A

Colours and light

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8
Q

What is the function of horizontal cells in the retina?

A

Lateral inhibition of photoreceptors either side of the activated photoreceptor preventing excess signals being sent to the brain

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9
Q

What is the function of bipolar cells in the retina?

A

Connect photoreceptors to axons

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10
Q

What artery supplies the retina with blood?

What is this a branch of?

What is this a branch of?

A

Central retinal artery

Ophthalmic artery

Ophthalmic artery branches from the internal carotid artery

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11
Q

What disease can fundoscopy reveal?

A

Hypertensive retinopathy

Diabetic retinopathy

Macular degeneration

Potential meningitis so can see papilloedmea

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12
Q

What blood vessel is occluded if a patient describes a curtain coming down on their vision?

What is this sign called?

A

Central retinal artery

Amaurosis fugax

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13
Q

Go to the last slide and label the retina (1):

A

1 = fovea
2 = macula
3 = central retinal artery
4 = central retinal vein
5 = optic disc

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14
Q

What is the name of the specialist technique used to visualise the layers of the retina?

A

Optical coherence tomography (OCT)

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15
Q

What are the 2 types of visual field?

A

Temporal visual field
Nasal visual field

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16
Q

What are the 2 types of retinal fibres in the optic nerve?

A

Nasal retinal fibres
Temporal retinal fibres

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17
Q

What retinal fibres are responsible for the nasal visual field?

A

Temporal fibres (since eye is a pinhole and inorder for light from the nasal field to hit the retina it must hit temporal fibres)

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18
Q

What retinal fibres are responsible for the temporal visual field?

A

Nasal fibres (for light to be detected from the temporal field it must come in and hit the nasal fibres)

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19
Q

How do the nasal fibres and temporal fibres differ in the way that they travel once they reach the optic chiasm?

A

Nasal fibres decussate and cross sides
Temporal fibres stay on the same side

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20
Q

What part of the brain do the nasal and temporal retinal fibres travel to following the optic chiasm?

A

Lateral Geniculate nucleus in the thalamus

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21
Q

What is the name of the structure following the optic chiasm?

A

Optic tract

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22
Q

What fibres (specifically which sides do the fibres come from) are contained within an optic tract?

Right optic tract

A

Ipsilateral (right) superior and inferior temporal fibres

Contralateral (left) superior and inferior nasal fibres

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23
Q

What are optic radiations?

A

The temporal and nasal fibres travelling on from the lateral geniculate nucleus to the primary visual cortex

24
Q

What are the 2 different types of optic radiation?

A

Superior optic radiations

Inferior optic radiations

25
Q

What lobe of the brain do the superior optic radiations travel through to reach the primary motor cortex?

A

Parietal lobe

26
Q

What lobe of the brain do the inferior optic radiations travel through to reach the primary visual cortex?

A

Temporal lobe

27
Q

Go to the last slide and draw tthe retinal fibres and their pathways:

A
28
Q

How are visual field defects named?

A

Named after the part of the vision that has been lot not where the lesion is located

29
Q

What are the names of all the structures running from the retinal fibres to the end?

A

Nasal and retinal fibres
Optic nerve
Optic chiasm
Optic tract
Lateral geniculate nucleus
Optic radiations (superior and inferior)
Primary visual cortex

30
Q

What is a Scotoma?

A

Localised defect in retina causing a small patch of visual loss

31
Q

What type of vision do we have?
What is it good for?

A

Binocular vision

Good for depth perception

32
Q

What type of visual defect is caused by an optic nerve lesion?

A

Monocular blindness

33
Q

What fibres are affected in a left sided optic nerve lesion casuing monocular blindness?

A

Temporal and nasal fibres on the Ipsilateral side (left)

Leads to Ipsilateral loss of temporal and nasal visual fields

34
Q

What type of visual loss is caused by a lesion at the optic chiasm?

A

Bitemporal hemianopia

35
Q

What fibres are affected in an optic chiasm lesion leading to Bitemporal hemianopia?

A

The nasal fibres on both sides leading to both temporal visual fields being lost

36
Q

What condition often leads to Bitemporal hemianopia?

A

Pituitary adenoma

37
Q

What visual field defect occurs as a result of a lesion in the optic tract?

A

Homonomous hemianopia

38
Q

What is homonomous hemianopia (optic tract lesion)?
What fields are lost?
What fibres are affected?

A

When the visual fields on the same side of thh eye are lost (right optic tract lesion means right side of both eyes visual fields are lost)

Ipsilateral temporal fibres damaged
Contralateral nasal fibres damaged

So Ipsilateral nasal field gone
Contralateral temporal field gone

39
Q

What visual fields are lost with left sided homonomous hemianopia?

A

Left eyes temporal field and right eyes nasal field

Right optic tract must be damaged

40
Q

What must be damaged if a patient has visual loss in quadrants?

A

Optic radiations

41
Q

What is responsible for the superior visual field (quadrant)?

A

Inferior optic radiations

42
Q

What is responsible for the inferior visual field (quadrant)?

A

Superior optic raiations

43
Q

What condition would be caused by damage to the right superior optic radiation?

A

So damage to the superior right temporal fibre+ damage to superior Left nasal fibre

So loss of vision in the INFERIOR right Nasal visual field and INFERIOR temporal visual field on the left

Called Homonomous inferior quadrantanopia

44
Q

What part of the brain does the superior optic radiation travel through?

A

Parietal lobe

45
Q

What visual field defect is produced by a lesion in the inferior optic radiation?

A

Homonomous superior quadrantopia

Superior nasal field on Ipsilateral side lost

Superior temporal field lost on Contralateral side

46
Q

What conditions often lead to both superior and inferior radiations being damaged?

Which blood vessel?

A

Stroke

Middle cerebral artery

47
Q

What visual field defect is caused by a stroke due to a middle cerebral artery occlusion damaging both the superior and inferior radiations on the same side?

A

Homonomous hemianopia

48
Q

What does occlusion of the posterior cerbral artery cause to the vision?

A

Contralateral homonomous hemianopia with macular sparing

49
Q

Why does macular sparring occur if a stroke is caused by the posterior cerbral artery?

A

It has a dual blood supply since it still receives blood from the middle cerebral artery

50
Q

What is the accommodation reflex?

A

Where you are able to focus on nearby objects

51
Q

What is the afferent and efferent for the accommodation reflex?

A

Afferent = optic nerve

Efferent = occulmotor nerve

52
Q

What are the 3 Cs of the accomodation reflex?

A

Convergence of eyes
Constriction of pupils
Convexity of lens to inc refractive power

53
Q

What is responsible for convergin the eyes in the accomadtion reflex?

A

Medial Rectus

54
Q

What is responsible for constriction of the pupils in the accomodation reflex?

A

Constrictor papillae

55
Q

What is responsible for fattening the lens in the accomadtion reflex??

A

Ciliary muscle

56
Q

What part of the brain processes in the accomadtion reflex?

A

Visual cortex via the lateral geniculate neucles
Then to oculomotr and edinger Westphal nuclei

57
Q

What is the pathway for the light reflex?

A

Light
Optic nerve
Pre-tectal nucleus
Then to both edinger westphal nuclei (parasympathic ganglionics)
Then to occulmotor nerve (ciliary ganglion) then sphincter pupillae

CNS (21 decks)

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