Lecture 7 - Orbit and Eye Flashcards

1
Q

what is the bony orbit?

A
  • bilateral, symetrical cavities containing the eyballs and associated structures
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2
Q

What bones/fractions of bones can be found in the bony orbit?

A
  • frontal bone
  • sphenoid bone
  • ethmoid bone
  • lacrimal bone
  • palatine bone
  • maxilla
  • zygomatic bone
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3
Q

What fissures/canals are in the bony orbit?

A
  • superior orbital fissure
  • inferior orbital fissure
  • optic canal
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4
Q

What nerves pass through the superior orbital fissure?

A
  • occulomtor nerve (CNIII)
  • trochlear nerve (CN IV)
  • ophthalmic divison of trigemincal nerve (CN V1)
  • abducens nerve (CN VI)
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5
Q

What nerve passes through the optic canal

A
  • optic canal (CN II)
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6
Q

What are the three layers of the eye? (from deep to superficial)

A
  • inner neural layer (retina)
  • middle vascular layer
  • outer fibrous layer
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7
Q

What structures are within the outer fibrous layer?

A
  • sclera
  • cornea
  • limbus
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8
Q

Cornea

A
  • first refraction of light entering eye
  • directs light to lens
  • avascular
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9
Q

Sclera

A
  • suppoetive outer white layer
  • attachment site for extraocular muscles
  • covered by mucous membranes (conjunctiva) to lubricate eye
  • vascular
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10
Q

Limbus

A
  • transition zone between cornea and sclera
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11
Q

What structures are within the middle vascular layer?

A

uvea:
- iris
- cilliary body
- choroid
- lens
- zonular fibers

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12
Q

Iris

A
  • contains pupillary dilator and sphincter muscles
  • controls pupil size depending on light and NS signals
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13
Q

Ciliary body

A
  • produces aqueous humour
  • contains ciliary muscles
  • helps focus lens using zonular fibers and ciliary muscles
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14
Q

lens

A
  • focuses light on retina
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15
Q

What are the three muscles in the middle vascular layer?

A
  • intraocular muscles
    -extraocular muscles
  • ciliary muscles
  • pupillary muscles
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16
Q

Intraocular vs extraocular muscles

A
  • intra = within the eye
  • extra = outside the eye
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17
Q

Ciliary muscles

A

contracts and relax to change lens so you can see close/far
- when looking far away, muscles contract

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18
Q

Pupillary muscles (3)

A
  • iris
  • sphincter pupillae
  • dilator pupillae
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19
Q

Sphincter pupillae

A
  • concentric muscle fibers
  • construct pupil when contracted
  • parasympathetic NS
20
Q

Dilator pupillae

A
  • muscle fibers run longitudinally towards margins of iris
  • enlarges pupils when contracted
  • sympathetic NS
21
Q

Pupil size when bright light or PSNS signals

22
Q

Pupil size when dim light or SNS signals

23
Q

Middle vascular layer - choroid

A
  • nourishes retina
  • maintains eye temp and volume
24
Q

Inner neural layer

25
Retina
- macula (fovea in centre) - optic disc - ora serrata - optic nerve
26
macula (fovea in centre)
- highest concentration of photoreceptor cells - rods and cones
27
optic disc
- where opti nerve exits the eye (optic nerve is made by retinal axons) - blind spot - no photoreceptors
28
ora serrata
anterior border of retina
29
optic nerve
accumulation of retinal axons
30
Myopia
- near-sightedness - lens or eyeball is too long - image is focused in front of fovea
31
Hyperopia
- far-sightedness - lens or eyeball is too short/flat - image is focused behind fovea
32
Chambers of the eye
- anterior chamber - posterior chamber - vitreous chamber
33
Which chambers are part of the anterior cavity?
- anterior chamber - posterior chamber
34
Which chambers are part of the posterior cavity?
- vitreous chamber
35
Anterior chamber
- between cornea and iris - filled with aqueous humor (maintains ocular pressure, replaced every 90 minutes)
36
Posterior chamber
- between iris and lens - important for production and circulation of aqueous humour
37
Vitreous chamber
- filled with gel-like vitreous humour
38
Vitreous humour
- maintains shape of eye - nourishes eye - attached to retina - makes up about 80% of eye volume - does not regenerate
39
Extraocular muscles (8)
- trochlea - superior oblique - superior rectus - medial rectus - lateral rectus - inferior rectus - inferior oblique - levator palebrae superioris
40
Movements of eye: superior oblique
down and out
41
Movements of eye: inferior oblique
up and out
42
What nerve innervates the extraocular muscles? With the exception of two of the muscles with are the...?
- the oculomotor nerve (CN III) - except for Superior Oblique and Lateral Rectus (SO-LAR)
43
What nerve innervates the superior oblique?
- trochlear nerve (CN IV) - trochleae = "pulley" = pulls eye
44
What nerve innervates the Lateral Rectus?
abducencs nerve (CN VI) - abducens abdcuts eye
45
What is the lacrimal apparatus?
system of glands and ducts - produces and drains lacrimal fluid (tears)
46
What do lacrimal fluid (tears) do?
- lubricate eye surface - removes debris from eye - about 1 mL produced each day
47
lacrimal apparatus components/structures
- lacrimal gland - excretory lacrimal ducts - superior and inferior puncta - superior and inferior lacrimal canaliculi - lacrimal sac - nasolacrimal duct