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Kaplan: Anatomy and Physiology Part III > Chapter 8: Visual Pathways > Flashcards

Chapter 8: Visual Pathways Flashcards

1
Q

Can vitamin A be synthesized by humans?

A

no

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2
Q

Describe the route traveled of the pupillary light reflex pathway of the afferent limb CN II?

A
  • Light stimulates ganglion retinal cells > impulses travel up CN II which projects bilaterally to the pretectal nuclei (midbrain)
  • pretectal nucleus projects bilaterally > Edinger- Westphal nuclei (CN III))
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3
Q

Describe the efferent limb of the pupillary light reflex pathway.

A

Edinger Westphal nucleus (preganglionic parasympathetic) > ciliary ganglion (postganglionic parasympathetic) > pupillary sphincter muscle > miosis

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4
Q

M3 activation of the ciliary muscle causes what actions?

A

contraction > accommodation for near vision

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5
Q

M3 blockade causing blockage of ciliary muscle activation leads to what actions?

A

relaxation > focus for near vision

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6
Q

What 3 events occur when an individual focuses on a nearby object

A
  1. accommodation
  2. convergence
  3. pupillary constriction (miosis)
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7
Q

Describe how convergence takes place?

A

parasympathetic fibers contract the ciliary muscle, which relaxes suspensory ligaments, allowing the lens to increase its convexity (becoming more round). This increases refractive index of lens thereby focusing nearby object

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8
Q

Describe how convergence takes place?

A

both medial rectus muscle contract adducting both eyes.

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9
Q

A term used in general to describe Argyll Robertson pupil?

A

pupillary light-near dissociationn

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10
Q

What are conditions in which Argyll Robertson pupil is seen?

A

neurosyphilis, diabetes

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11
Q

How is relative afferent pupil (Marcus Gunn) pupil caused? (Where is the lesion?)

A

lesion of the afferent limb of the pupillary light reflex

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12
Q

How do you diagnose Marcus Gunn pupil?

A

swinging light reflex diagnosis made with swinging flashlight

Shine light in Marcus Gunn pupil > pupils do not constrict fully

Shine light in normal eye > pupils constrict fully

Shine light immediately again in affected eye > apparent dilation of both pupils because stimulus carried through that CN II is weaker; seen in MS

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13
Q

Can enophthalmos be a feature of Horner’s syndrome? What is it?

A

yes; posterior displacement of the globe in an anteroposterior plane within the orbit.

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14
Q

What is Adie pupil caused by?

A

ciliary ganglion lesion

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15
Q

Symptoms of Adie pupil?

A

dilated pupil that reacts sluggishly to light, but better to accommodation; often seen in women and often associated with loss of knee jerks

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16
Q

What eye symptom does transtentorial uncal herniation lead to and what is the pathology?

A

increased intracranial pressure> leads to uncal herniation > CN III compression> fixed and dilated pupil, “down and out” eye, ptosis

17
Q

What type of light do rods respond to?

A
  • achromatic
  • low - light sensitive
  • night vision, motion
18
Q

What type of light do cones respond to?

A
  • red, green, blue
  • chromatic
  • bright light sensitive
  • object recognition
19
Q

Lesion of the left optic nerve?

A

anopia of left eye

20
Q

Lesion of lateral part of left optic nerve?

A

left nasal hemianopia

21
Q

A lesion of the optic chiasm?

A

bitemporal heteronymous hemianopia

22
Q

A lesion of the left optic tract?

A

right homonymous hemianopia

23
Q

Lesions damaging Meyer’s loop leading to the lingual gyrus on the left?

A

right homonymous superior quadrantanopia

24
Q

Lesions damaging the fibers going to the cuneus gyrus on the left side.

A

right homonymous inferior quadrantanopia

25
Q

If there was a lesion of the posterior cerebral artery of the left side what would the eye defect be?

A

right homonymous hemianopia with macular sparing

26
Q

What conditions can lead to lesions of the optic nerve?

A

optic neuritis, central retinal artery occlusion

27
Q

What conditions could lead to lateral occlusion of the optic nerve?

A

internal carotid artery aneurysm

28
Q

What can cause obstruction of the optic chiasm?

A
  • pituitary adenoma (begins as superior quadrantanopia )
  • craniopharyngioma (begins as inferior quandrantonopia
29
Q

Lesions past the optic chiasm produce ipsilateral or contralateral defects?

A

contralateral defects

30
Q

What are some lesions that can cause damage to the optic tract?

A

vascular

31
Q

What are some lesions that can cause damage to the Meyers loop tract?

A

posterior cerebral artery occlusion

32
Q

How does MS affect the optic nerve?

A

unilateral optic nerve lesions are seen in MS, where there is an immune related inflammatory demyelination of the nerve. Lesion typically presents with a central scotoma due to involvement of deep fibers in the nerve from the macula

Kaplan: Anatomy and Physiology Part III (13 decks)

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