How does the eye see (anatomy) Flashcards

1
Q

What protects the eye from a direct blow from any object of diameter greater than that of the orbital rim?

A

The orbital margins

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2
Q

Which parts of the orbit are most often affected in an orbital blow out fracture?

A

The medial wall of the orbit and the orbital floor (extremely thin 0.5-1mm)

-orbital rim remains in tact

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3
Q

When might the infraorbital canal/infraorbital NVB be damaged and what does this mean?

A

When the fractured zygoma rotates medially

-this will result in a general sensory deficit of the facial skin

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4
Q

Sphincter of the eye

Fibres surround the eyelids used to “screw up the eyes”

A

Orbicularis oculi

-used in blinking

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5
Q

Orbicularis oculi

A

Screw up the eyes

-within the eyelids, used in blinking

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6
Q

What is the purpose of the orbital septum?

A

Helps prevent the spread of infection from superficial (periorbital cellulitis) to deep (orbital cellulitis)

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7
Q

Muscle which raised the eyelid?

A

Levator palpebrae superioris

-contains skeletal and smooth muscle

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8
Q

Function of the tarsal glands?

A

Lipid secretion

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9
Q

What is the conjunctival formix?

A

Where the conjunctiva is reflected off the sclera and onto the internal aspect of the eyelid

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10
Q

Sympathetic nerve supply to the lacrimal gland?

A

CN VII

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11
Q

This ducts carries tears to the inferior meatus of the nasal cavity

A

Nasolacrimal duct

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12
Q

The 2 corneal reflections and their significance

A

The nasal and temporal (used clinically to track the symmetry of bilateral eye position/movements)

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13
Q

The 2 layers of the fibrous layer of the eye

A

The sclera

Cornea

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14
Q

Protective/attachment for the extra-ocular muscles

A

The sclera

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15
Q

Provides 2/3rds of the eye’s refractive power

A

The cornea

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16
Q

Controls the iris, the shape of the lens and the secretion of aqueous humor

A

The ciliary body

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17
Q

What is the choroid responsible for?

A

Nutrition and gaseous exchange for the other layers

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18
Q

is the common location of “floaters” caused by areas of liquefaction of the gel & clumping of collagen fibres/cells

A

Vitreous body

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19
Q

What is the anterior chamber?

A

The space between the cornea and the iris: contains aqueous

20
Q

What is in the posterior chamber?

A

Contains the lens and aqueous humor

Located between the iris and the ciliary body

21
Q

What is in the posterior segment of the eye?

A

Sclera, choroid, retina, vitreous body

22
Q

The 3 layers of the retina

A

1) photoreceptors
2) ganglion cells (anterior to the photoreceptors)
3) The axons of the ganglion cells (lie anterior to photoreceptor cells and ganglion cells)

The retinal veins and retinal arteries lie anterior to the retina

23
Q

Where are the visual cortices?

A

In the occipital lobes

24
Q

Function of levator palpebrae superioris?

A

Lifts the upper eyelid

25
Q

Where do all of the rectus muscles originate from?

A

The common tendinous ring (attached to bones surrounding the optic canal)

26
Q

This muscle attaches to the anteromedial floor of the orbit

A

The inferior oblique

27
Q

LR6

A

Lateral Rectus

CNVI (abducent nerve)

28
Q

SO4

A

Superior oblique

CNIV (trochlear nerve)

29
Q

AO3

A

All others

CNIII (oculomoter nerve)

30
Q

Secretes aqueous

A

Ciliary body

31
Q

Route of aqueous

A

1) circulates around lens within posterior chamber
2) Then into pupil and anterior chamber
3) Then reabsorbed into the scleral venous sinus (Canal of Schlemm) at the iridocorneal angle

32
Q

Where is CNII formed from all of the axons leaving the retina?

A

Formed at the optic disc

33
Q

What is the fundus?

A

The retina + macula + fovea centralis + optic disc

34
Q

The opthalmic artery is a branch of which artery?

A

The internal carotid

35
Q

How to tell the difference between the internal and external carotid artery? e.g. if they gave you a prosection of just the neck and you couldn’t tell?

A

The internal carotid has no branches in the neck!

36
Q

The opthalmic artery travels in which canal?

A

The optic canal

37
Q

Nasal branches of which artery contribute to Kiesselbach’s area?

A

Nasal branches of the opthalmic artery

38
Q

The only vein draining the retina?

A

The central vein of the retina

39
Q

What is an end artery?

A

An artery with insufficient anastamoses to maintain viability of the tissue supplied if arterial occlusion occurs

40
Q

What is the danger triangle of the face?

A

The upper lip and the external nose

-here you can have retrograde spread of infection via superficial veins into the cranial cavity

41
Q

The inferior opthalmic vein drains into which vein?

A

Drains into the superior opthalmic vein

-this then drains posteriorly into the cavernous sinus (via the superior orbital fissure)

42
Q

Which arteries and veins are responsible for the “red eye” appearance in flash photography?

A

The ciliary arteries and veins of the uvea

43
Q

The blind spot of the visual field corresponds to this

A

The optic disc

44
Q

The only point of entry/exit from the retina for blood vessels and the axons of CNII?

A

The optic disc

45
Q

Retinal artery occlusion and retinal vein occlusion

A

complete interruption of flow in a retinal artery branch/”branch” retinal vein = loss of an area of visual field corresponding to the area of ischaemia
b) complete interruption of flow of the central artery (end artery) or vein = monocular blindness