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RB Y2 Ophthamology > Anatomy: The Orbit and the Eye > Flashcards

Anatomy: The Orbit and the Eye Flashcards

1
Q
A
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2
Q

where is the optic canal

A
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3
Q

how many bones make up the orbit

A

6

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4
Q

what is the thinnest bone of the optic canal

A

ethmoid - medial wall

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5
Q

where is the apex of the bony orbit located

A

nasal side

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6
Q

what bones form the orbital margins

A
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7
Q

what forms the orbital rim

A

combiend orbital margins

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8
Q

what function does the orbital rim have in respect to orbital trauma

A

nothing wider than diameter of orbital rim can hit the eye

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9
Q

describe the angle of the orbital rim

A
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10
Q

orbital blowout fracture

A

force on orbital rim damages medial wall (ethmoid) and orbital floor (maxilla) which are extremely thin

can damage the infraorbital NVB resulting in general sensory deficit of facial skin

typically entraps the inferior rectus - patients will complain of pain on upward gaze

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11
Q

which direction does a fractured zygoma tend to rotate, and what can this result in clinically

A

medially towards orbit floor

as the suspensory ligament of the eye attaches to the zygoma laterally, the eye may be lowered towards the orbital floor

results in diploplia (double vision)

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12
Q

what is the difference between notch and foramen

A

notch is an incomplete circle

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13
Q

outer eyelid:

name the 2 parts of the orbicularis oculi

A
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14
Q

describe the functions of the orbital and paplebral parts of the orbicularis oculi

A

orbital part closes the eye tightly

palpebral part is involved in normal blinking

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15
Q

what is the orbicularis oculi innervated by

A

CNVII

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16
Q

what is another name for the superior tarsal muscle (connective tissue?)

A

Muller’s muscle

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17
Q

medial eyelid layer:

A
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18
Q

what is the orbital septum made of and what is its function

A

sheet of fascia

helps to prevent spread of infection from superficial to deep

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19
Q

inner eyelid layer:

tarsal glands

A

also called Meibomian glands

glands embedded in the tarsal muscles, responsible for lipid secretion

they secrete a layer of oil on top of tears to stop them from evaporating

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20
Q
A
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21
Q

tears:

  • antibacterial properties
  • pH
A

antibacterial properties due to action of lysozyme

pH of around 7.6

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22
Q

describe the conjunctiva - 2 types and where they meet

A

the inner surface of the eyelid is lined by palpebral conjunctiva

the eyeball is lined by bulbar conjunctiva

meet at the fornix

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23
Q

conjunctival fornix

A

connects the conjunctiva lining the inside of the eyelid with that covering the eyeball

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24
Q

describe the features of the palpebral conjunctiva

A

has follicles and papillae

contains goblet cells which secrete part of the tear film

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25
Q

which conjunctiva is more vascular

A

palpebral

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26
Q

describe the movement the eyelid makes when shutting

A

sweeping action - lateral to medial

this helps to wash debris towards the lacrimal sac

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27
Q

what is the iris covered by

A

cornea

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28
Q

what is the sclera covered by and what is it’s function

A

conjunctiva

  • forms a defensive barrier to foreign bodies penetrating deep to the orbit
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29
Q
A
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30
Q

describe the lacrimal apparatus

A

lacrimal gland produces lacrimal fluid (parasympathetic CNVII)

  • this washes medially over eye toward medial angle
  • drains through lacimral puncta (openings in lacrimal papillae)
  • goes through canaliculi to lacrimal sac
  • and then nasolacrimal duct to reach inferior meatus in nose
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31
Q

what is the parasympathetic innervation of the lacrimal gland

A

CNVII

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32
Q
A
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33
Q

what can corneal light reflections be used for clinically

A

clinically to track the symmetry of bilateral eye positions/movements

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34
Q

what forms the outer layer of the eye

A

sclera and cornea

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35
Q

what holds 2/3 of the eye’s refractive (focusing) power

A

the cornea

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36
Q

describe the layers of the cornea

A
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37
Q

how is the transparency of the cornea maintained

A

the endothelium maintains transparency by pumping fluid out of the stroma

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38
Q

where is the cornea thickest

A

peripherally

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39
Q

what is the stroma of the cornea formed by

A

reguarly spaced collagen fibres

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40
Q

what are the outer and inner parts of the lens known as

A

cortex and nucleus

41
Q

what forms the middle (uvea - vascular layer) of the eye

A

the uveal tract structures are continuous with eachother and pigmented

42
Q

function of iris

A

controls pupil diameter

43
Q

function of ciliary body

A

controls iris, shape of lens (ciliary muscle) and secretion of aqueous humour (ciliary epithelium)

44
Q

function of choroid

A
  • nutrition and gas exchange
  • supplies the outer retina
45
Q

what forms the inner layer of the eye

A

retina - photosensitive layer

46
Q

describe the chambers of the anterior segment of the eye

A

anterior chamber between cornea and iris contains aqueous humour

posterior chamber between iris and suspensory ligaments contains aqueous humour

47
Q

how much of the eye does the posterior segment occupy

A

2/3rds

48
Q

what does the posterior segment of the eye contain

A

vitreous body/humour

  • clear gel
49
Q

what is a common location for floaters in the eye

A

vitreous body in posterior segment

50
Q

cataract

A

clouding of the lens

51
Q
A
52
Q

define limbus

A

border of cornea and sclera

53
Q

describe the circulation of aqueous

A
54
Q

how does the composition of aqueous fluid allow for optical clarity

A

low protein content

55
Q

what angle is being referred to in ‘open’ and ‘closed’ glaucoma

A

the iridocorneal angle

56
Q

what does raised intraocular pressure cause

A

ischaemia of the retina and glaucoma

57
Q

what is in the cavernous system

A

cavernous sinus

internal carotid artery

CNIII, IV, V1, V2, VI

58
Q
A
59
Q
A
60
Q

Kiesselbach’s area

A
61
Q

what type of artery is the central artery of the retina

A

end artery - insufficient anastomoses to maintain viability of the tissue supplied if arterial occlusion occurs

62
Q

what are the central artery and vein of the retina contained in

A

optic nerve (CNII)

63
Q

what is the ophthalmic artery a branch of

A

internal carotid artery

64
Q

what supplies the outer layers of the retina

A

the choroid

65
Q
A
66
Q

where does the inferior ophthalmic vein drain into

A

superior ophthalmic vein

  • to cavernous sinus
67
Q

where does the superior ophthalmic vein leave the eye

A

via the superior orbital fissure

68
Q

which cranial nerves exit the cranial cavity via the superior orbital fissure

A

CNIII, IV, V1 and VI

69
Q

danger triangle

A

infection from here can spread to brain via cavernous sinus

eg from popping spot

(unlikely though)

70
Q

fundus

A

interior surface of the eye

includes retina, fovea, macula and optic disc

can be visualised with fundoscopy

71
Q

optic disc

A

point of CNII formation - the only point of entry and exit for blood vessels and CNII axons

72
Q

where is one’s blind spot

A

optic disc - there are no photoreceptors

15 degrees temporally in the visual field

73
Q

where is the greatest density of cones

A

macula

74
Q

where is the fovea

A

centre of macula

it is a small depression in the macula which provides the most acute vision

75
Q

describe the layers of the retina

A
76
Q

what is the optic nerve formed from

A

the axons of the ganglion cells

77
Q

how does monocular blindness occur

A

complete interruption of flow of central artery (end artery) or vein

78
Q

how does loss of an area of visual field occur

A

complete interruption of flow in a retinal artery branch/retinal vein

79
Q
A

Right eye:

80
Q

which optic nerves cross at the optic chiasma

A

nasal retina nerves

81
Q

where is light from objects in the right visual field processed by

A

left primary visual cortex

82
Q

where do the rectus muscles originate from and insert onto

A

originate from common tendinous ring

insert onto sclera

83
Q

name the extraocular muscles

A
84
Q

where do the oblique muscles insert

A

onto sclera

85
Q

what does the levator palpebrae superioris do

A

lift the upper eye lid

86
Q

describe the somatic innervation of the EO muscles

A
87
Q

which EO muscles dont have secondary movements

A

medial and lateral rectus

88
Q

what is the primary position of the eye

A

gaze directed forward

89
Q

which EO muscle passes through the trochlea

A

superior oblique (supplied by CNIV)

90
Q

lateral rectus movement and clinical testing

A

can only abduct (CNVI)

  • bring line of gaze into that of sup and inf rectus
91
Q

superior rectus movement and clinical testing

A

when in abduction, can only elevate

(CNIII)

92
Q

inferior rectus movement and clinical testing

A

when in abduction, can only depress

(CNIII)

93
Q

medial rectus movement and clinical testing

A

can only adduct the eyeball

brings line of gaze into that of sup and inf oblique

94
Q

inferior oblique movement and clinical testing

A

when in adduction, can only elevate

(CNIII)

95
Q

superior oblique movement and clinical testing

A

when in adduction, can only depress

(CNIV)

96
Q

which muscles produce the movement of pure elevation

A

superior rectus and inferior oblique

  • SR adduction and IO abduction cancel each other out
97
Q

which muscles produce the movement of pure depression

A

superior oblique (abduction) and inferior rectus (adduction)

98
Q

what is the strongest eye muscle

A

medial rectus - maybe due to the ammount of accomodation performed

RB Y2 Ophthamology (20 decks)

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