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MC - Neurologia, Neurocirurgia e Neurociência > EYES > Flashcards

EYES Flashcards

1
Q

EYEBALL AND OPTIC NERVE

Components in the eyeball

(light must pass through before reaching the retina)

A

cornea - aqueous humor - pupil - lens - vitreous humor

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2
Q

EYEBALL AND OPTIC NERVE

Components of the retina

(layers and cells)

A

Ganglion Layer

(axons = optic nerve)

Inner Nuclear Layer

(bipolar cells)

Outer Nuclear Layer

(nuclei of rods and cones)

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3
Q

EYEBALL AND OPTIC NERVE

How do rods and cones transduce light energy?

A

rods and cones absorb photons

→

conformational changes in the photopigments

→

sodium channels close

→

hyperpolarization

→

reduction of NT release

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4
Q

EYEBALL AND OPTIC NERVE

True or false: rods and cones release less NT in the light and more NT in the the dark

A

TRUE

photons stimulates the sodium channels to close, causing hyperpolarization. Thus, in the dark, there is despolarization process, determinating the release of NT

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5
Q

EYEBALL AND OPTIC NERVE

Vitamin A function

A

Vit A is necessary for retinal transduction

+

cannot be synthesized

=

deficiency causes night blindness

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6
Q

EYEBALL AND OPTIC NERVE

Impulse’s traject in the retina layers

A

rods and cones (outer nuclei layer)

→

bipolar cells (inner nuclei layer)

→

ganglion cells (axons = optic nerve)

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7
Q

EYEBALL AND OPTIC NERVE

Optic nerve traject

A

axons of ganglion cells converge at the optic disc

(myelination process from the oligodendrocytes)

→

optic nerve enters the cranial cavity

(optic foramen)

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8
Q

EYEBALL AND OPTIC NERVE

Glaucoma: concept

A

Increase of intraocular pressure

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9
Q

EYEBALL AND OPTIC NERVE

Glaucoma: open-angle

A

Chronic, painless and progressive condition

+

Decrease reabsorption of aqueous humor

+

visual loss and blindness

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10
Q

EYEBALL AND OPTIC NERVE

Glaucoma: narrow-angle

A

Acute (painful) or Chronic (genetic) condition

+

Blockade of Canal of Schlemm

+

Emergency treatment

(surgery + cholinomimetics, carbonic anhydrase inhibitors and/or mannitol)

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11
Q

EYEBALL AND OPTIC NERVE

Photoreceptor rods

(1 kind)

A

Achromatic

+

Low-light sensitive

+

Night vision

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12
Q

EYEBALL AND OPTIC NERVE

Photoreceptors cones

(3 kinds)

A

red + green + blue

chromatic

bright light sensitive

object recognition

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13
Q

VISUAL PATHWAY

The eye inverts images like a camera, so …

(nasal vs temporal)

A

Nasal retina receives information from temporal hemifield

+

Temporal retina receives information from nasal hemifield

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14
Q

VISUAL PATHWAY

At the optic chiasm, from which half do the fibers of retina cross and project into the colateral optic tract ?

(nasal or temporal)

A

NASAL

almost 60% of the fibers cross

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15
Q

VISUAL PATHWAY

Do the fibers from temporal retina cross ?

A

NO

only ipsilateral optic tract

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16
Q

VISUAL PATHWAY

components of optic nerve

vs

components of optic tract

A

OPTIC NERVE

nasal and temporal fibers from the ipsilateral retina

OPTIC TRACT

temporal fibers from ipsilateral retina

+

nasal fibers from contralateral retina

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17
Q

VISUAL PATHAWAY

Fibers from optic tract project to …

(4)

A

Lateral Geniculate Nucleus

(most fibers)

Superior Colliculi

(reflex gaze)

Pretectal Area

(light reflex)

Suprachiasmatic Nucleus

(circadian rhythms)

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18
Q

VISUAL PATHWAY

Most important pathway

(visual pathway)

A

optic tract

→

lateral geniculate body

→

primary visual cortex

(Brodmann area 17, in occiptal lobe, via optic radiations)

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19
Q

VISUAL PATHWAY

Components of visual cortex (striate cortex)

(3)

A

striate cortex is divided by calcarine sulcus

→

cuneus gyrus

(superior in cortex - receives medial fibers)

lingual gyrus

(inferior in cortex - receives lateral fibers)

20
Q

VISUAL PATHWAY

Axons from lateral geniculate body that project to visual cortex are known as …

A

optic radiations

or

visual radiations

or

geniculocalcarine tract

21
Q

VISUAL PATHWAY

Components of visual radiations

(lateral geniculate body → visual cortex)

(2)

A

LATERAL FIBERS

visual information from lower retina

(upper contralateral visual field)

→

temporal lobe (Meyer Loop) to lingual gyrus

MEDIAL FIBERS

visual information from upper retina

(lower contralateral visual field)

→

parietal lobe to cuneus gyrus

22
Q

VISUAL REFLEXES

Pupillary Light Reflex

A

impulse in optic nerve (stimulated by light)

→

pretectal area

→

Edinger-Westphal nucleus

(bilateral)

→

preganglionic parasympathetic fibers to ciliary ganglion

(by oculomotor nerve)

→

pupillary sphincter muscle (miosis)

→

direct light reflex (ipsilateral)

+

consensual light reflex (contralateral)

23
Q

VISUAL REFLEXES

Accommodation - Convergence Reaction

(components)

A

Focus on a nearby object

=

Accommodation

+

Convergence

+

Miosis

24
Q

VISUAL REFLEXES

Accommodation - Convergence Reaction

(accomodation)

A

Edinger-Westphal send preganglionic parasympathetic fibers by oculomotor nerve to ciliary ganglion

→

Ciliary ganglion send postganglionic parasympathetic fibers suply ciliary muscle

→

ciliary muscle contration = suspensory ligaments of the lens relaxation = increase of convexity = increase of refractive index

25
Q

VISUAL REFLEXES

Accommodation-Convergence Reaction

(convergence)

A

both medial rectus muscles contract

→

adducting both eyes

(oculomotor nerve)

26
Q

VISUAL REFLEXES

Accommodation-Convergence Reaction

(miosis)

A

Edinger-Westphal nucleus

→

preganglionic parasympathetic fibers to ciliary ganglion

(by oculomotor nerve)

→

pupillary sphincter muscle (miosis)

27
Q

CLINICAL CORRELATE

What is the predominant innervation in the eye (PANS or SANS)?

A

Parasympathetic Nervous System

→

muscarinic antagonists + ganglionic blockers

(large pharmacological effect)

28
Q

CLINICAL CORRELATE

Pupillary Sphincter Muscle (iris)

(predominant receptor + stimulation + blockade)

A

M3 receptor (PANS)

+

stimulation = miosis

+
blockade = mydriasis

29
Q

CLINICAL CORRELATE

Radial Dilator Muscle (iris)

(predominant receptor + stimulation + blockade)

A

Alpha receptor

(SANS)

+

stimulation = mydriasis

+

blockage = miosis

30
Q

CLINICAL CORRELATE

Ciliary Muscle

(predominant receptor + stimulation + blockade)

A

M3 receptor (PANS)

+

stimulation = accommodation

+

blockade = focus for far vision

31
Q

CLINICAL CORRELATE

Ciliary Body Epithelium

(predominant receptor + stimulation + blockade)

A

Beta receptor (SANS)

+

stimulation = increase of aqueous humor

+
blockade = decrease of aqueous humor

32
Q

CLINICAL CORRELATE

Pupillary Abnormalities

Argyll Robertson Pupil

A

NO light reflexes (direct and consensual)

NORMAL accommodation reflex

+

seen in neurosyphilis, diabetes

33
Q

CLINICAL CORRELATE

Pupillary Abnormalities

Horner Syndrome

A

Lesion in oculosympathetic pathway

+

PANS > SANS

→

miosis + ptosis + enophthalmos + hemianhidrosis

34
Q

CLINICAL CORRELATE

Pupillary Abnormalities

Relative Afferent Pupil

(Marcus Gunn)

A

Lesion in afferent fibers

→

pupil don’t constrict fully

+
when shine light immediately against affected eye, apparent dilation

+

seen in multiple sclerosis

35
Q

CLINICAL CORRELATE

Pupillary Abnormalities

Adie Pupil

A

ciliary ganglion lesion

+

accommodation reflex > light reflex

+

women, loss of knee jerk

36
Q

CLINICAL CORRELATE

Pupillary Abnormalities

Transtentorial (uncal) Herniation

A

“down-and-out” eye

+

dilated and fixed pupils

+

ptosis

+

increase of intracranial pressure = uncal herniation = compression of III cranial nerve

37
Q

CLINICAL CORRELATE

Lesions of the retina that includes macula destruction

(3)

A

macula is sensitive to trauma, intense light, aging and neurotoxins

+

central scotoma

+

common in Multiple Sclerosis

(auto-immune demyelination of the nerve)

38
Q

CLINICAL CORRELATE

Lesions in the optic nerve

(3)

A

blindness (anopia)

+

direct light reflex - NO

consensual light reflex - YES

+

optic neuritis and central retinal artery occlusion

39
Q

CLINICAL CORRELATE

Compression of optic chiasm

(2)

A

bitemporal heteronymous hemianopia

(peripherical vision)

+

pituitary tumor, meningioma

40
Q

CLINICAL CORRELATE

Internal carotid artery aneurysm

(2)

A

temporal retina fibers

+

ipsalteral nasal hemianopia

41
Q

CLINICAL CORRELATE

Lesions in the optic tract

(3)

A

vascular causes

+

homonymous hemianopia

+
always contralateral defects

42
Q

CLINICAL CORRELATE

Lesion of the visual radiations

(3)

A

contralateral homonymous quadrantanopia

+

Meyer Loop - Lateral fibers - Lower retina = superior quadrantanopia

(middle cerebral artery occlusion)

+

Via parietal lobe - medial fibers - superior retina - inferior quadrantanopia

(posterior cerebral artery occlusion)

43
Q

CLINICAL CORRELATE

Lesions of the primary visual cortex

A

contralateral homonymous hemianopia

(macular/central vision spared)

44
Q

CLINICAL CORRELATE

Lesions of the visual radiations are more common than lesions of optic tract?

A

TRUE

45
Q

CLINICAL CORRELATE

Lesions of the visual radiations and primary cortex: are pupillary reflexes present?

A

YES

cortical blindness

=

blindness

+

pupillary reflexes

MC - Neurologia, Neurocirurgia e Neurociência (13 decks)

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