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Neuro (NSB) > Eyes- Myrna > Flashcards

Eyes- Myrna Flashcards

1
Q

give 6 functions of the eyelid

A
  1. protection
  2. exclude light
  3. sweep foreign body from anterior surface
  4. spread tear film
  5. lubricate edges of lids
  6. pump ocular tear film
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2
Q

what are the 5 muscles of the eyelid and what part of ANS innervates each?

A
  1. orbicularis oculi- parasympathetic, motor of CN VII; only muscle that contributes significantly to closure of lids
  2. retractor anguli oculi: parasympathetic; pulls eyelids from sides so eye not perfect circle
  3. levator anguli oculi: parasympathetic
  4. levator palpebrae superioris: parasympathetic, CIII; main muscle that elevates the upper lid
  5. muller’s muscle: sympathetic of CN V; sympathetic; keeps lids tonically retracted
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3
Q

what nerves are sensory to the eyelid?

A

branches of V (trigeminal)

maxillary division:
zygomaticotemporal nerve: lateral dorsal lid
zygomaticofacial: lateral ventral lid

ophthalmic division:
frontal (supraorbital) nerve: middle portion of upper lid
infratrochlear nerve: medial dorsal and ventral lid

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4
Q

what are the 4 parts of the nasolacrimal system?

A
  1. lacrimal gland
  2. gland of the 3rd eyelid
  3. precorneal tear film
    -lipid (meibum; prevents evaporation)
    -serous: watery
    -mucous: from conjunctival goblet cells
  4. drainage system for tears:
    -dorsal and ventral puncta, then to dorsal and ventral canaliculi, out through nasolacrimal sac
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5
Q

what is the function of the precorneal tear film? (4)

A
  1. maintain optically uniform surface
  2. remove foreign material and debris
  3. provide nourishment to cornea (cornea avascular)
  4. prevent infection
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6
Q

where is aqueous humor located?

A

anterior and posterior CHAMBERS!;
posterior chamber has anterior and posterior segments!!
posterior segment also called vitreous body/vitreous chamber

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7
Q

what is the function of the fibrous layer of the eye? (4)

A
  1. optical element
  2. protection
  3. determines shape of globe
  4. site of insertion of extraocular muscles
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8
Q

describe the relative hydration of the cornea and how this is problematic based on its structure

A

must be dehydrated to be transparent; but is essentially a sponge in a liquid sandwich, anteriorly covered by tears and posteriorly covered by aqueous humor; so is very easy to get water-logged and hazy and since it is so thin this condition can progress quickly to eye bursting

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9
Q

what are the 4 visible parts of the iris?

A
  1. peripheral ciliary zone (thickest outermost part)
  2. collarette: lighter ring; birth defects originate here
  3. central pupillary zone
  4. pupillary border: right around pupil
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10
Q

what is the main function of the ciliary body?

A

accomodation via movement of zonules to change shape of lens capsule and lens

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11
Q

what organ has the highest protein content in the body?

A

the lens of the eye!

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12
Q

how is the lens held in place?

A

by zonules/zonary fibers that attach to the lens capsule

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13
Q

what are the 3 functions of the vitreous body?

A
  1. transmit light
  2. maintain shape of eye
  3. maintain normal position of retina
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14
Q

what are the 3 functions of the retinal pigmented epithelium? (outermost layer of neuroepithelial tunic)

A
  1. location of the blood retinal barrier
  2. transportation of retinol
  3. phagocytosis and degradation of photoreceptor disc
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15
Q

what is in the inner and outer layer of the photoreceptor layer of the neuroepithelial tunic?

A

inner: mitochondria
outer: discs and photopigments

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16
Q

describe the intraocular portion of the optic nerve (3 portions)

A
  1. retinal: optic disc, papilla, nerve head; forms a physiologic cup
  2. choroidal
  3. scleral: contains lamina cribrosa
17
Q

describe the orbital part of the optic nerve (3)

A
  1. from the lamina cribrosa to the optic foramen
  2. covered by meningeal sheaths
  3. considered a nerve fiber tract
18
Q

describe the intracranial portion of the optic nerve

A
  1. from optic canal to optic chiasm
  2. most fibers cross or decussate
  3. percentage of crossing depends on the species
19
Q

describe optic tracts

A
  1. continuations of optic nerve as crossed and uncrossed fibers
  2. synapse in 3 places:
    -with lateral geniculate body to make up the optic radiation to the visual cortex
    -with rostral colliculus for orientation to visual stimuli; sensitive to horizontal stimulus movement
    -with pretectal nucleus as efferent parasympathetic occulomotor nuclei
20
Q

what is the ocular fundus? what is it composed of? (4)

A

the internal surface of the posterior aspect of the eye;
1. retina
2. retinal vessels
3. optic disc
4. parts of the choroid and sclera that may be seen through the retina

21
Q

compare and contrast a transilluminator and a direct ophthalmoscope

A

transilluminator is a bright diffused light source that is useful for PLRs and basic eval of adnexa (everything but eye and optic nerve) and globe

while a direct ophthalmoscope is a bright focused light source that can localize lesions within globe and is designed to evaluate the fundus

22
Q

what is tropicamide used for?

A

short acting mydriatic (dilating) agent for eye exam; parasympathetic

23
Q

what is proparicaine used for?

A

topical numbing agent for eye exam and diagnostic if patient too painful to examine; is epitheliotoxic so don’t send home for pain management

24
Q

describe the schirmer tear test

A

measures aqueous part of tear film, but must get logistics right

25
Q

how is fluorescein stain used in eye exam?

A

detecting corneal ulceration; attaches to hydrophilic stroma of cornea and will stick anywhere there is a gap

26
Q

describe tonometry/glaucoma test

A

measure intraocular pressure (glaucoma = elevated IOP, low IOP = uveitis)
can use pen with local anesthetic or tonovet without anesthetic

27
Q

what are the 5 reflexes/responses of the neuroophthalmic exam? describe

A
  1. PLR: stimulus is light, receptor in retina, afferent neuron is CN II, efferent is CN III, effector is iris sphincter muscle, response is pupil constriction
  2. dazzle: stimulis is bright light; receptor in retina; afferent CN II; efferent CN VII; effector is orbicularis oculi; response is blink or retraction
  3. menace: stimulus is hand motion, receptor in retina, afferent is CN II, efferent is CN VII; effector is orbicularis oculi, response is blink or retract
  4. palpebral blink: stimulus is touching eyelids, receptors in skin, afferent in CN V (either ophthalmic or maxillary branches), efferent is CN VII, effector is orbicularis oculi, response is blink
  5. corneal blink: stimulus is touching cornea, receptors in cornea, afferent is CN V (oph), efferent is CN VII, effector is orbicularis oculi, response is blink

Neuro (NSB) (19 decks)

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