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Ophthalmology Week 1 > Anatomy of the Orbit and the Eye > Flashcards

Anatomy of the Orbit and the Eye Flashcards

1
Q

what bones are part of the bony orbit?

A

-frontal, zygomatic, maxilla, nasal, sphenoid, ethmoid, lacrimal

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2
Q

what are the 2 important notch/foramen in the bony orbit?

A

supraorbital notch/foramen and the infraorbital foramen

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3
Q

what is the difference between a notch and a foramen?

A

a foramen is a complete circle and a notch is more ‘C’ shaped

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4
Q

what is the apex if the bony orbit?

A

optic canal

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5
Q

what shape is the bony orbit?

A

pyramidal

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6
Q

what is the base of pyramid known as clinically?

A

orbital rim

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7
Q

what creates the orbital rim?

A

combined superior, inferior, medial and lateral orbital margins

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8
Q

what protects the eye from a direct blow?

A

the orbital rim

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9
Q

why do smaller objects cause a direct blow to the eye?

A

they are smaller than the orbital rim and orbital rim doesnt protect it

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10
Q

which part(s) of the orbit are commonly affected by blowout fractures?

A

medial wall and orbital floor

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11
Q

why are the medial wall and orbital floor more commonly affected by blowout fractures?

A

they are extremely thin

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12
Q

what can happen after a blow out fracture and what NVB can be damaged?

A

orbital contents can become trapped, infraorbital NVB can be damaged

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13
Q

what bone does the infraorbital NVB pass through before passing through the infraorbital foramen?

A

the maxillary

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14
Q

what is th outcome of the infraorbital NVB being damaged?

A

general sensory deficit of facial skin

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15
Q

what is the external layer of the eyelid?

A

orbicularis oculi muscle

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16
Q

what are the 2 parts of the orbicularis oculi?

A

orbital part and palpebral part

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17
Q

what is just deep the orbicularis oculi?

A

the orbital septum

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18
Q

what is the orbital septum?

A

a sheet of fascia

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19
Q

what does the orbital septum do?

A

helps prevent spread of infection from superficial to deep

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20
Q

how many tarsi is the around the eye?

A

2 - superior and inferior

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21
Q

what are the tarsi?

A

plates of fibrous connective tissue

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22
Q

why is the superior tarsus important?

A

gives shape and support to the eye and is an attachment point for muscles

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23
Q

what are embedded in the tarsi?

A

tarsal glands

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24
Q

what is the function of the tarsal glands?

A

secrete lipid substance

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25
Q

what is the function of the lipid secreted by the tarsal glands?

A

stops tears from overflowing and stops eyes sticking together when we blink

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26
Q

what is the limbus?

A

the junction between the cornea and the sclera

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27
Q

what is the sclera covered by?

A

conjunctiva

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28
Q

what is the coloured part of the eye called?

A

iris

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29
Q

in conjuctivitis, what is it that becomes dilated and inflamed?

A

conjuctival vessels

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30
Q

what is the tiny black dot on the inferior medial aspect of the lower lid known as?

A

inferior lacrimal papilla and punctum

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31
Q

what is the function of the inferior papilla and punctum?

A

it is an opening which tears go through to get into nasolacrimal duct

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32
Q

where is the location of the lacrimal gland?

A

superior lateral aspect of eyelid

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33
Q

what is located in the medial angle of the eye?

A

lacrimal lake

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34
Q

what CN gives the parasympathetic control to the lacrimal gland to produce tears?

A

CN VII

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35
Q

where does the nasolacrimal duct drain into?

A

inferior meatus

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36
Q

what is corneal reflections used to test?

A

the symetry of bilateral eye positions/movements

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37
Q

what are the 3 layers of the eye?

A

fibrous, uvue and retina

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38
Q

what is the outer layer of the eye?

A

fibrous layer

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39
Q

what are the 2 parts to the fibrous layer?

A

sclera and cornea

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40
Q

what is the sclera important for?

A

muscle attachment

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41
Q

what is meant by refractive power?

A

the ability to focus light

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42
Q

how much of the refractive power is the cornea responsible for?

A

2/3rd

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43
Q

what is the middle layer of the eye?

A

the uvea (vascular layer)

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44
Q

what are the 3 parts to the uvea?

A

the iris, the ciliary body and the choroid

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45
Q

what is the function of the iris?

A

control pupil diameter. moves to adjust amount of light coming through the cornea

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46
Q

what is the function(s) of the ciliary body?

A

help control iris, controls the shape of the lens, and secretes aqueous humour

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47
Q

what is the photosensitive layer of the eye?

A

the retina

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48
Q

what is the inner layer of the eye?

A

the retina

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49
Q

what are the segments of the eye?

A

anterior and posterior segments

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50
Q

what is classed as the anterior segment the eye?

A

infront of the lens

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51
Q

what chambers is the anterior eye divided in to?

A

anterior and posterior chamber

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52
Q

where is the anterior chamber of the anterior segment found?

A

between the cornea and the iris

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53
Q

what does the anterior segment contain?

A

aqueous humour

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54
Q

what is the posterior chamber of the anterior segment of the eye between?

A

between the iris and suspensory ligaments

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55
Q

what does the posterior chamber contain?

A

aqueous humour

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56
Q

what is the function of the aqueous humour?

A

to provide nutrition to the iris and cornea as they dont have a blood supply

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57
Q

where is the posterior segment of the eye?

A

everything posterior to the lens

58
Q

what does the posterior segment of the eye contain?

A

vitreous body

59
Q

what is within the vitreous body?

A

virtreous humour

60
Q

what is vitreous humour?

A

gel-like liquid

61
Q

where is a common location for ‘floaters’ in the eye and what causes them?

A

in the vitreous body, caused when the gel starts to solidify a bit and clump together with collagen fibres

62
Q

where does the circulation of the aqueous begin?

A

in the ciliary body

63
Q

what secretes the aqueous?

A

ciliary processes

64
Q

after the ciliary processes has secreted the aqueous, where does it circulate and why?

A

within the posterior lens, to nourish lens

65
Q

how does the aqueous pass into the anterior chamber?

A

through the pupil

66
Q

when the aqueous passes through the pupil, what does it nourish?

A

the cornea

67
Q

where is the aqueous reabsorbed?

A

into scleral venous sinus

68
Q

what else is the scleral venous sinus known as?

A

canal of Schlemm

69
Q

where abouts is the canal of schlemm?

A

at iridocorneal angle

70
Q

what are the 3 parts of the retina? (there is more but only need to learn these)

A

the optic disc, the macula and the fovea

71
Q

where is the point of formation of CN II?

A

optic disc

72
Q

what is the function of the optic disc?

A

point of formation of CN II, only point of exit/entry for blood vessels and axons of CN II

73
Q

why does the optic disc give rise to a blind spot?

A

there is no cones or rods, nothing to pick up light

74
Q

where in the retina has the greatest density of cones?

A

the macula

75
Q

what are cones and rods?

A

photoreceptors

76
Q

which type of photoreceptor is more active during daylight?

A

cones

77
Q

what photoreceptors do we use in dim light?

A

rods

78
Q

where is the fovea?

A

the centre of macula

79
Q

how deep is the depression in the macula that creates the fovea?

A

1.5mm depression

80
Q

what is important about the fovea?

A

area of most acute vision

81
Q

what is the arterial supply to the retina?

A

the central artery of the retina

82
Q

what is the clinical importance of the central artery of the retina?

A

it is an end artery so it it gets blocked the retina dies

83
Q

where do the retina artery and vein enter the retina?

A

through the optic disc

84
Q

what does light have to pass through in the retina before it reaches the retina?

A

the axons of the ganglion cells, the ganglian cells and also the blood vessels

85
Q

what is in the most posterior layer of the retina?

A

the photoreceptors

86
Q

what lies anterior to the photoreceptor cells in the retina?

A

the ganglion cells

87
Q

what lies anterior to the gnaglion cells in the retina?

A

the axons of the ganglion cells

88
Q

where do the retinal veins and arteries lie in relation to the retina?

A

anterior to the retina

89
Q

where is light from the right visual field processed?

A

left primary visual cortex

90
Q

where is light from the lower visual filed processed by?

A

by the superior part of the primary visual cortex

91
Q

where does light from the right visual field hit the retina?

A

the right nasal retina

92
Q

how does light recieved by the right nasal retina, move to be processed by the left primary visual cortex?

A

it crosses at the optic chiasm

93
Q

if light hits the temporal retina, does it cross at the optic chiasm or remain on the same side?

A

stay on same side

94
Q

arterial supply to the orbit?

A

ophthalmic artery

95
Q

what artery does the ophthalmic artery branch from?

A

the internal carotid artery

96
Q

what does the internal carotid pass through before giving off the ophthalmic artery?

A

passes through the carotid canal and through the cavernous sinus.

97
Q

what different branches does the ophthalmic artery give rise to?

A
  • nasal cavity branches
  • forehead (scalp) branches
  • ciliary arteries
  • the central artery of the retina
98
Q

where does the ciliary branches supply?

A

the middle layer of the eye- uvea

99
Q

what is the only vein that drains the retina?

A

the central vein of the retina

100
Q

what is the main venous drainage of the orbit?

A

the superior ophthalmic vein

101
Q

what will the superior ophthalmic vein eventually drain to?

A

cavernous sinus

102
Q

what does the superior ophthlamic vein go through to reach the cavernous sinus?

A

the superior orbital fissure

103
Q

where else can the orbit drain to anteriorly other than the superior ophthalmic vein?

A

facial vein

104
Q

where does the inferior ophthalmic artery mainly drain in to?

A

the superior ophthalmic vein

105
Q

where is the danger triangle on the face?

A

from the corners of the lips to the root of the nose

106
Q

why is the danger triangle considered dangerous?

A

it is thought that if a spot is squeezed here a vein can be easily squeezed which leaves it susceptible to bacteria getting into the vein and due to the facial veins having communications through the orbit and canvernous sinus, then infection could spread to here

107
Q

how many extraocular skeletal muscles are there?

A

7

108
Q

what are the 7 extraocular skeletal muscles?

A
  • superior, inferior, medial and lateral rectus
  • superior and inferior oblique
  • levator palpebrae superiosis
109
Q

where do the 4 rectus muscles all originate from?

A

the common tendinous ring

110
Q

where is the common tendinous ring?

A

around the optic canal

111
Q

where do all 4 rectus muscles insert onto?

A

the sclera

112
Q

where do the 2 oblique muscles attach onto?

A

the sclera

113
Q

what is the function of the levator palpebrae superiosis?

A

lifts the upper lid

114
Q

what does the superior oblique muscle pass through before attaching to the sclera?

A

the trochlear

115
Q

what does the trochlear do?

A

it is basically a pulley, makes a turn in the tendon of the superior oblique muscle so it attaches to sclera at an oblique angle.

116
Q

what nerve supplies the somatic motor innervation to the lateral rectus muscle?

A

CN VI - abducent nerve

117
Q

what nerve supplies the superior oblique muscle with somatic motor innervation?

A

CN IV - trochlear nerve

118
Q

exluding the lateral rectus and superior oblique, what is the motor innervation to all the other extraocular muscles?

A

CN III - oculomotor nerve

119
Q

what are the 3 different axis’ of the eyeball?

A

vertical axis, transverse axis, anteroposterior axis

120
Q

if the eye moves in the vertical axis, what movements can it be doing?

A

adduction and abduction

121
Q

which movements can the eye do if it is moving in the transverse axis?

A

elevation/depression

122
Q

where is the anteroposterior axis running through?

A

runs straight through the direction of the gaze

123
Q

what movements can the eye undertake if it is moving along the anteroposterior axis?

A

intorsion/extorsion

124
Q

what is meant by intorsion of the eyeball?

A

medial rotation

125
Q

what is meant by extorsion?

A

lateral rotation of the eyeball

126
Q

where is the apex of the orbit (optic canal) located relative to the rest of the orbit?

A

medially located

127
Q

what causes the difference in the orbital axis and the optical axis?

A

the orbital axis points out at an angle due to medially positioned apex of orbit

128
Q

most of the extrocular muscles have secondary movements on top of their primary movements, except which 2 muscles?

A

medial and lateral rectus

129
Q

what is meant by the primary position of the eyeball?

A

gaze directed forward

130
Q

to test the function of a particular muscle (and its nerve) what must you do?

A

line up gaze to the plane of muscles being tested and isolate muscle movement

131
Q

what is the only function of the lateral rectus?

A

abduct eyeball

132
Q

when the eyeball is abducted, it brings the line of gaze into the same plane as what?

A

superior and inferior rectus

133
Q

in what position should the eyeball be in to assess superior rectus and why?

A

in abduction as in abduction the superior rectus can only elevate

134
Q

why should the eyeball be abducted when assesing inferior rectus?

A

inferior rectus can only depress when eyeball is abducted so assessing its individual function

135
Q

what is the only function of the medial rectus?

A

adduct the eyeball

136
Q

when the eyeball is adducted, what planes is in now in line?

A

same plane as superior oblique and inferior oblique attachments

137
Q

in what posision should the eyeball be to test inferior oblique?

A

in adduction

138
Q

if the inferior oblique is working correctly, how will it move the eyeball in adduction?

A

it will elevate the eyeball

139
Q

when eyeball is in adduction, what is the only function of the superior oblique?

A

can only depress the eyeball

140
Q

what muscles are responsible for pure elevation?

A

superior rectus and inferior oblique

141
Q

what muscles are responsible for pure depression?

A

inferior rectus and superior oblique

142
Q

what is meant by yolk movement?

A

cant just move one eye at a time

Ophthalmology Week 1 (6 decks)

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