2: Anatomy - orbit and eye Flashcards

1
Q

What is the bony orbit?

A

Hole in the skull which the eyeball (globe) sits in

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2
Q

Which cranial bones make up the bony orbit?

A

Frontal bone

Maxilla

Zygoma

Sphenoid bone

Ethmoid bone

Lacrimal (a new one)

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3
Q

What are two important features of the frontal bone related to the bony orbit?

A

Orbital plate - the part of the frontal bone on the inside of the orbit

Supraorbital notch - or foramen, if it’s closed

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4
Q

What is an important feature of the maxilla in relation to the bony orbit?

A

Infraorbital foramen

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5
Q

Which important structures travel through the supraorbital and infraorbital notches?

A

Neurovascular bundles

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6
Q

What is an important feature of the sphenoid bone which transmits the optic nerve and blood vessels of the bony orbit?

Which feature of the sphenoid bone transmits other nerves and is found close to this structure?

A

Optic canal

Superior orbital fissure

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7
Q

What space is found inferior and lateral to the optic canal?

Which bone are it and the optic canal found in?

A

Superior orbital fissure

Sphenoid bone

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8
Q

The edges of the bony orbit are called ___.

A

margins

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9
Q

What are the superior, inferior, medial and lateral margins of the bony orbit collectively called?

A

Orbital rim

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10
Q

Where is the apex of the bony orbit found?

A

Optic canal

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11
Q

The apex of the bony orbit is slightly (medial / lateral).

A

medial

or nasal

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12
Q

The superior, inferior, medial and lateral margins are collectively known as the ___ ___.

A

orbital rim

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13
Q

How does the orbital rim protect the eye?

A

Anything larger in diameter than the orbital rim cannot make contact with the eye

So it protects the eye from direct trauma

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14
Q

Which is more anterior:

superior orbital margin

inferior orbital margin?

A

superior orbital margin

where your eyebrows sit

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15
Q

The orbital rim is fairly (thick / thin).

A

thin

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16
Q

What name is given to fractures of the medial and inferior orbital margins?

A

Orbital blowout fracture

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17
Q

What can be compromised by an orbital blowout fracture?

A

Inferior neurovascular bundle

e.g infraorbital nerve, a branch of CN V2 (maxillary division of trigeminal nerve)

causing a sensory deficit to maxillary skin

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18
Q

What would happen if CN V2 was damaged by an orbital blowout fracture?

A

Loss of sensation to maxillary region of skin

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19
Q

Which structure holds the eye in place and can be damaged by a zygoma fracture?

A

Suspensory ligament

Eye drops towards floor of orbit, causing diplopia (double vision)

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20
Q

Which circular muscle surrounds the eye and is responsible for closing the eyelids?

A

Orbicularis oculi

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21
Q

What is the function of the orbicularis oculi muscle?

A

Closes the eyelids

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22
Q

What are the two parts of the orbicularis oculi muscle?

A

Orbital (outer)

Palpebral (inner)

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23
Q

Which sheet of fascia connects the orbital rim to the eyelids?

A

Orbital septum

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24
Q

Which bits of fascia hold the shape of the upper and lower eyelids?

A

Superior tarsus and inferior tarsus

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25
Q

The tendon of which muscle attaches to the superior tarsus and helps to lift the superior eyelid?

A

Levator palpebrae superioris

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26
Q

Which muscles are responsible for

a) opening the superior eyelid
b) closing both eyelids?

A

a) Levator palpebrae superioris

b) Orbicularis oculi

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27
Q

Which ligaments hold the shape of the eye?

A

Medial palpebral ligament

Lateral palpebral ligament

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28
Q

Name the following structures:

a) Hold the shape of the superior and inferior eyelids (2)
b) Hold the general shape of the eye (2)
c) Extends as a sheet from the orbital rim to the eyelids (1)
d) Attaches to the superior eyelid and helps open it (1)
e) Closes both eyelids

A

a) Superior and inferior tarsus

b) Medial and lateral palpebral ligaments

c) Orbital septum

d) Tendon of levator palpebrae superioris

e) Orbicularis oculi

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29
Q

Name the important connective tissue structures of the eyelids.

A

Orbital septum

Superior and inferior tarsus

Tendon of levator palpebrae superioris

Medial and lateral palpebral ligaments

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30
Q

Which glands secrete lipids into the eye?

A

Tarsal glands

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31
Q

What is the purpose of the fluid secreted by the tarsal glands?

A

Stops the eyelids from sticking together

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32
Q

Which structures cover the

a) iris and pupil
b) sclera?

A

a) Cornea

b) Conjunctiva

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33
Q

Which structures are covered by the:

a) conjunctiva
b) cornea?

A

a) Sclera

b) Iris and pupil

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34
Q

The lacrimal gland is found in the superior and lateral part of the eye.

Where does lacrimal fluid drain?

Where exactly is it found?

A

Inferior lacrimal papilla

Inferior and medial part of the eye

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35
Q

Through which structure in the inferior lacrimal papilla does lacrimal fluid drain?

A

Lacrimal punctum

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36
Q

Lacrimal fluid is secreted from the ___ ___ and drains through the ___ ___ ___ via a small ___.

A

lacrimal gland

inferior lacrimal papilla

punctum

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37
Q

Which cranial nerve supplies the lacrimal glands?

Is it sympathetic or parasympathetic?

A

CN VII (Facial nerve)

Parasympathetic

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38
Q

Once lacrimal fluid has drained through the punctum of the inferior lacrimal papillae, which structures does it pass through?

A

Canaliculi

Lacrimal sac

Nasolacrimal duct…

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39
Q

The lacrimal gland is supplied by (sympathetic / parasympathetic) fibres of CN ___.

A

parasympathetic fibres of CN VII (Facial nerve)

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40
Q

What is the rough diameter of the eyeball in cm?

A

2.5 cm

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41
Q

Which structure is found in the centre of the iris?

A

Pupil

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42
Q

What is another name for the eyeball?

A

Globe

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43
Q

Name the three layers of the eye from outer to inner.

A

Fibrous layer

Uvea / vascular layer

Retina

44
Q

The eye is made up fibrous, ___ and retinal layers.

A

vascular (uvea)

45
Q

Which structures are found in the fibrous layer of the eye?

A

Sclera

Cornea

46
Q

The cornea is responsible which percentage of the eye’s refractive power?

A

66%

47
Q

The uvea of the eye is highly ___.

A

vascular

48
Q

Which structure of the vascular layer controls the diameter of the pupil?

A

Iris

49
Q

Which structure of the vascular layer controls the iris, the shape of the lens and secretion of aqueous humour?

A

Ciliary body

50
Q

Which structures are responsible for

a) pupil diameter
b) secretion of aqueous humour
c) shape of lens
d) nutrition and gas exchange?

A

a) Iris

b) Ciliary body

c) Ciliary body

d) Choroid

51
Q

The ___ nourishes the eye.

A

choroid

52
Q

What are three important parts of the retina?

A

Optic disc

Macula

Fovea

53
Q

Apart from the three layers, the eye is further subdivided into ___ and ___.

A

segments

chambers

54
Q

Which segment of the eye has two chambers?

A

Anterior segment

55
Q

The anterior chamber of the anterior segment of the eye is the space between the ___ and iris.

A

cornea

56
Q

The posterior chamber of the anterior segment of the eye is the space between the iris and the ___ ___.

A

suspensory ligaments

57
Q

The anterior segment of the eye contains (aqueous / vitreous) humour.

A

aqueous humour

58
Q

The posterior segment of the eye is found behind the ___.

A

lens

59
Q

The posterior segment of the eye contains (aqueous / vitreous) humour.

A

vitreous humour

60
Q

What is the junction between the sclera and the cornea called?

A

Limbus

61
Q

Which angle is important in glaucoma and is found in the anterior chamber?

A

Iridocorneal angle

62
Q

What produces aqueous fluid in the posterior chamber?

A

Ciliary body

Remember this is part of the uvea (vascular layer of the eye)

63
Q

Aqueous fluid is produced by the ___ ___ and then moves from posterior to anterior before draining where?

A

ciliary body

iridocorneal angle

64
Q

Aqueous fluid drains into what at the iridocorneal angle?

A

Scleral venous sinus

65
Q

Aqueous fluid secretion and drainage affects what property of the eye?

A

Intra-ocular pressure

66
Q

Through which neck blood vessel does oxygenated blood reach the ophthalmic artery?

Which space within the cranial cavity does this blood vessel run in?

A

Internal carotid artery

Cavernous sinus

67
Q

What is the important end artery supplying the back of the eye?

A

Central artery of the retina

68
Q

The central artery of the retina passes within which important structure to supply the back of the eye?

A

Optic nerve (CN II)

69
Q

What is the only vein to drain the retina?

A

Central vein of the retina

70
Q

Which veins drain the bony orbit?

A

Superior and inferior ophthalmic veins

Which drain into the cavernous sinus eventually

71
Q

What is the danger triangle of the face?

A

Area comprising upper lip and nose

Facial veins here have NO VALVES, so if bacteria get into them they can travel through the veins of the bony orbit to the cavernous sinus and cause infections like meningitis

So don’t pop spots here

72
Q

With regards to the retina, what is the entire posterior area which absorbs light?

A

Fundus

73
Q

What are the three important structures found in the fundus of the retina?

A

Optic disc

Macula

Fovea

74
Q

Which part of the retina is a blind spot?

Why?

A

Optic disc

Where CN II forms and blood vessels enter and exit

75
Q

The macula has the greatest number of (rods / cones).

A

cones

Responsible for acute colour vision

76
Q

What area is found at the centre of the macula and is capable of the most acute vision?

Why?

A

Fovea

Has the greatest density of cones

77
Q

Describe the layers of the retina from posterior to anterior.

A

Posterior to anterior:

Photoreceptors (which absorb light)

Ganglion cells

Axons of ganglion cells

Then blood vessels

(Weird because you’d think photoreceptors would be closest to the light)

78
Q

Are there photoreceptors in the optic disc?

A

No, optic disc is where CN II and blood vessels are

“Blind spot”

79
Q

Which retinal vessels have to be occluded to cause

a) isolated areas of visual field loss
b) total visual field loss?

A

a) Retinal artery / vein

b) Central artery / vein of the retina

80
Q

Which terms describe vision

a) towards the nose
b) away from the nose?

A

a) Nasal

b) Temporal

81
Q

Light from objects in the right visual field are processed by the (right / left) visual cortex.

A

Right visual field > Left visual cortex

82
Q

Light from objects in the left visual field is processed by the (left / right) visual cortex.

A

Left visual field > Right visual cortex

83
Q

** In general, light coming FROM the left is processed on the right side and vice versa **

Same for up and down

A
84
Q

There are seven extra-ocular muscles. What are they called?

A

Rectus muscles - superior, inferior, medial and lateral

Oblique - superior and inferior

Levator palpebrae superioris

85
Q

What does the levator palpebrae superioris do?

A

Lifts upper eyelid

86
Q

What is the origin of the rectus muscles?

A

Common tendinous ring

87
Q

What is the insertion of all the extraocular muscles apart from levator palpebrae superioris?

A

Sclera

88
Q

What is the trick for remembering the innervation of the extraocular muscles?

A

LR6 SO4 AO3

LATERAL RECTUS - CN VI - ABDUCENT NERVE

SUPERIOR OBLIQUE - CN IV - TROCHLEAR NERVE

ALL OTHERS - CN III - OCULOMOTOR NERVE

89
Q

LR_ SO_ AO_

A

LR6 SO4 AO3

90
Q

__6 __4 __3

A

LR6 SO4 AO3

91
Q

Which cranial nerves supply

a) medial rectus
b) lateral rectus
c) inferior oblique
d) orbicularis oculi
e) superior oblique

A

a) CN III

b) CN VI

c) CN III

d) CN VII

e) CN IV

LR6 SO4 AO3

92
Q

What movements can the eye make on the vertical axis?

A

Abduction (temporally)

Adduction (nasally)

93
Q

What movements can the eye make on the transverse axis?

A

Elevation

Depression

94
Q

What movements can the eye make on the AP axis?

A

Intorsion (upper eye twists towards nose)

Extorsion (upper eye twists towards temple)

95
Q

The optic disc is ___.

The macula is ___.

(nasal , temporal)

A

Optic disc is NASAL

Macula is TEMPORAL

96
Q

Why is the axis of the orbit different from the optical axis (i.e the way the eyeballs face)?

A

Apex of orbit (marked by optic canal) is slightly nasal (medial)

97
Q

What is the action of the lateral rectus?

A

ABDUCTS eyeball

98
Q

What muscle needs to ABDUCT the eyeball to test the action of two other muscles?

What muscles are these?

A

Lateral rectus

Superior and inferior rectus

99
Q

What is the innervation of lateral rectus?

A

CN VI (Abducent nerve)

Remember LR6

100
Q

What is innervation of

a) superior rectus
b) inferior rectus?

What actions do they have when the eyeball is ABDUCTED by lateral rectus?

A

Both innervated by CN III (Oculomotor nerve)

a) Elevates eyeball

b) Depresses eyeball

WHEN ABDUCTED BY LATERAL RECTUS

101
Q

Which muscle’s action is required to test superior and inferior rectus?

A

Lateral rectus (abduction)

102
Q

What is the action of the medial rectus muscle?

Which nerve innervates it?

A

ADDUCTION of the eyeball

CN III (Oculomotor nerve)

103
Q

Which muscle’s action is required to test the superior and inferior oblique muscles?

A

Medial rectus (adduction)

104
Q

Which nerves innervate

a) superior oblique
b) inferior oblique?

What actions do these muscles have when the eyeball is adducted by medial rectus?

A

a) CN IV (Trochlear nerve)

b) CN III (Oculomotor nerve)

Superior oblique DEPRESSES the eyeball

Inferior oblique ELEVATES the eyeball

The opposite of what you learned before, for the craic

105
Q

With the eyes in the central position, which muscles act synergistically to

a) elevate
b) depress the eyes?

A

a) Inferior rectus and Superior oblique

b) Superior rectus and Inferior oblique