Ophthalmology Flashcards

1
Q

What are the 7 bones that make up the orbital wall

A

Orbital plate of frontal
Orbital plate of ethmoid
Orbital plate of maxilla
Palatine bone
Sphenoid bone
Zygomatic bone
Lacrimal bone

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2
Q

What are the orbital walls

A

Roof - orbital plate of frontal bone and lesser wing of sphenoid
Floor - orbital plate of maxilla and palatine
Medial - orbital plate of ethmoid, lacrimal and maxilla
Lateral - zygomatic and greater wing of sphenoid

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3
Q

What are the structures in the orbital walls that allow exit/entry of structures

A

Optic canal
Superior orbital fissure
Infraorbital foramen
Supraorbital notch

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4
Q

Name A-J

A

A- greater wing of sphenoid bone
B- superior orbital fissure
C- lesser wing of sphenoid bone
D- frontal bone
E- optic canal
F- ethmoid bone
G- Lacrimal bone
H- palatine bone
I- Maxilla
J- zygomatic bone

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5
Q

Name A-L

A

A- orbital plate of frontal bone
B- Optic canal
C- Superior orbital fissure
D- Infraorbital foramen
E- Orbital plate of ethmoid
F - Supraorbital notch
G- Frontal bone
H- Zygomatic bone
I- Maxilla bone
J- Sphenoid bone
K- Ethmoid bone
L- Lacrimal bone

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6
Q

Name A-D

A

A- supraorbital notch
B- Optic canal
C- Superior orbital fissure
D- Infraorbital foramen

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7
Q

What structure does optic canal transmit

A

Optic nerve
Ophthalmic artery

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8
Q

What structure does Superior orbital fissure transmit

A

Oculomotor nerve CN III
Trochlear nerve CN IV
Abducens nerve CN VI
Superior ophthalmic vein
Frontal nerve (branch of trigeminal)
Lacrimal nerve (branch of trigeminal)

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9
Q

Frontal nerve is a branch of

A

Ophthalmic division of trigeminal nerve CNV1

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10
Q

Lacrimal nerve is a branch of

A

Ophthalmic division of trigeminal nerve CNV1

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11
Q

Infraorbital foramen allows the passage of

A

Infraorbital nerve
infraorbital neurovascular bundle

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12
Q

Infraorbital nerve is a branch of

A

Maxillary division of trigeminal nerve CN V2

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13
Q

Supraorbital notch allows the passage of

A

Supraorbital nerve
Supraorbital neurovascular bundle

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14
Q

Supraorbital nerve is a branch of

A

ophthalmic division of trigeminal nerve

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15
Q

Which part of the orbital wall is the weakest

A

Inferior wall

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16
Q

Which orbital wall may also be damaged when the inferior orbital wall is damaged

A

Medial wall

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17
Q

Why do blowout fractures occur

A

Because the orbital rim is tough whereas the orbital wall is weaker hence pressure is transferred to the orbital walls and cause a fracture there instead

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18
Q

Which wall is most susceptible to blowout fractures

A

Inferior orbital wall

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19
Q

What can happen due to blowout fractures

A

Orbital fat herniates into maxillary sinus
Trap structures
- inferior rectus muscle -> unable to depress the eye
- infraorbital nerve -> parasthesia of face

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20
Q

Where does infraorbital nerve innervate

A

Sensory innervation to the skin of lower eyelid, side of nose, anterior cheek, upper lip

Hence blowout fractures affecting infraorbital nerve can cause parasthesia in those areas

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21
Q

What is the most superficial muscle of the eyelid

A

Orbicularis oculi muscle

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22
Q

What are the 2 parts of orbicularis oculi muscle

A

Orbital part
Palpebral part

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23
Q

Function of the parts of orbicularis oculi

A

Orbital - TIGHTLY closes the eyelid
Palpebral - GENTLY closes the eyelid

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24
Q

Innervation of orbicularis oculi

A

Facial nerve CN VII (it is a muscle of facial expression)

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25
Q

What are the structures deep to orbicularis oculi

A

Superior and Inferior tarsal plates
Medial and lateral palpebral ligaments
Levator palpebrae superioris
Orbital septum

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26
Q

Name A-F

A

A- lateral palpebral ligament
B- tendon of Levator palpebrae superioris
C- superior tarsal plate
D- medial palpebral ligament
E- inferior tarsal plate
F- orbital septum

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27
Q

What structures are in the tarsal plates

A

Meibomian glands

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28
Q

Function of meibomian glands

A

Secrete meibum to
- prevent evaporation of tear film
- prevent eyes sticking together when closed

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29
Q

Function of the orbital septum

A

Prevent spread of infection between superficial and deep parts of the orbit

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30
Q

Where does levator palpebrae superioris attach to

A

From sphenoid bone -> superior tarsal plate

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31
Q

What are the 2 components of levator palpebrae superioris

A

LPS and superior tarsal muscle (Smooth muscle)

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32
Q

Name A-D

A

A- levator palpebrae superioris
B- orbicularis oculi muscle
C- meibomian gland
D- superior tarsal muscle

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33
Q

Function of LPS

A

LPS- elevates upper eyelid
Superior tarsal muscle - widening eyes

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34
Q

Innervation of LPS

A

LPS - oculomotor nerve
Superior tarsal muscle - sympathetic nervous system

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35
Q

Where is the lacrimal gland located

A

Superolaterally at upper eyelid

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36
Q

Innervation of lacrimal gland

A

Secretomotor: Parasympathetic axons from CN VII
Sensory: lacrimal nerve from ophthalmic division of trigeminal nerve

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37
Q

Describe how does lacrimal fluid move

A
  1. Produced in lacrimal gland and washes over the eye
  2. Pushed over to the medial angle every time we blink
  3. Drains through the lacrimal puncta
  4. Than to the canaliculi -> lacrimal sac -> nasolacrimal duct
  5. Nasolacrimal duct drain into the inferior meatus in nasal cavity
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38
Q

Where does the nasolacrimal duct drain into

A

Inferior meatus of nasal cavity

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39
Q

Name A-E

A

A- Lacrimal gland
B- Canaliculi
C- Lacrimal sac
D- Lacrimal puncta
E- Nasolacrimal duct

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40
Q

What does the conjunctiva cover

A

The sclera and the inside of eyelids

It does not cover the cornea

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41
Q

The conjunctiva is avascular/vascular

A

Vascular

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42
Q

Name A-F

A

A- iris covered by cornea
B- conjunctival vessel
C- lower eyelid lined by conjunctiva
D and E- white sclera covered by conjunctiva
F- corneoscleral junction

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43
Q

Name A-C

A

A- Iris
B- Pupil
C- Cornea

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44
Q

What is the outermost layer of the eye

A

Fibrous layer consisting
- sclera (posterior 5/6)
- cornea (anterior 1/6)

45
Q

What are the features of the cornea

A

It is densely innervated
It provides 2/3 of refractive power
It is completely avascular

46
Q

Since the cornea is completely avascular, what structures supplies its nutrition

A

Aqueous humour in anterior chamber

47
Q

Which nerve innervates the cornea

A

Ophthalmic division of Trigeminal CNV1

48
Q

Function of sclera

A

Provides attachment for extra ocular muscles

49
Q

The sclera is avascular/vascular

A

Vascular but less vascularised than conjunctiva

50
Q

What is the 2nd layer of the eye

A

Uvea - consisting of iris, ciliary body and choroid

51
Q

What are the 3 parts of uvea

A

Iris
Ciliary body
Choroid

52
Q

The uvea is avascular/vascular

A

Vascular

53
Q

Function of the iris

A

Pigmented membrane with a central opening (pupil) which can be adjusted in size in response to light

54
Q

What muscles control the size of the iris

A

Dilator pupillae muscle
Sphincter pupillae muscle

Theses are within the iris

55
Q

How does the pupil dilate (mydriasis)

A

When the dilator pupilllae muscle contract

56
Q

Innervation of the dilator/sphincter pupillae muscle

A

Dilator - sympathetic
Sphincter - parasympathetic

57
Q

Function of the ciliary muscle

A

Control shape of lens for accomodation
Produce aqueous humour

58
Q

What are the 2 parts of ciliary body

A

Ciliary muscle - consist of smooth muscles
Ciliary processes

59
Q

Function of the choroid

A

Highly vascularised to provide nutrition and gas exchange to outer layers of the retina

60
Q

What are the 2 segments of the eye

A

Anterior
Posterior

61
Q

Where is the anterior segment located at

A

In front of the lens

62
Q

What are the 2 parts of anterior segment

A

Anterior chamber
Posterior chamber

63
Q

Describe the location of anterior and posterior chambers of the anterior segment

A

Anterior chamber - between cornea and iris
Posterior chamber- between iris and suspensory ligaments

64
Q

What is contained in the anterior segment of the eye

A

Aqueous humour produced by ciliary muscles

65
Q

What is contained in the posterior segment of the eye

A

Vitreous body containing vitreous humour

66
Q

Describe the circulation of aqueous humour

A
  1. Ciliary body and process secretes the aqueous humour
  2. The aqueous humour circulates within the posterior chamber and nourishes the lens
  3. The aqueous then passes through pupil into anterior chamber to nourish the cornea from the posterior aspect
  4. Aqueous reabsorbed into scleral venous sinus at iridocorneal angle -> drained into systemic venous system
67
Q

Where is the scleral venous sinus located at

A

Iridocorneal angle

68
Q

What holds the canal of schlemm (scleral venous sinus) open

A

Trabecular meshwork

69
Q

What happens when the trabecular meshwork is blocked

A

Acute angle closure glaucoma

70
Q

What is the interior (posterior) surface of the eye called

A

fundus

71
Q

What structures does the fundus consist of

A

Retina
Optic disc
Macula
Fovea

72
Q

What are the 4 layers of the retina, from deepest to most superficial

A

Retinal pigment epithelium
Photoreceptors
Bipolar neurons
Ganglion neurons

73
Q

Since the photoreceptors of the retina is at the deep layer of retina, it means that

A

Light needs to pass through the layers of neurons and capillaries before it reaches the photoreceptors

74
Q

The axons of the ganglion neurons come together to form the

A

Optic disc

75
Q

Why is the optic disc called the blind spot

A

Because there are no photoreceptors there

76
Q

Optic disc is the only point of

A

entry/exit for blood vessels and axons
the axons exit the optic disc to form the optic nerve

77
Q

What is the macula

A

Center of the retina which has the greatest density of cones

78
Q

Rods vs cones

A

Cones
- can provide coloured vision,
- activated at high levels of light (due to less pigments) ,
- for high visual acuity

79
Q

Function of the macula

A

Central high acuity coloured vision

80
Q

What is the fovea

A

Depression at the center of macula for high acuity vision

81
Q

Name A-L

A

A- Anterior chamber
B- Cornea
C- corneoscleral junction
D- ciliary body and muscle
E- Ciliary process
F- Optic nerve
G- Central retinal vein and artery
H- Fovea
I- sclera
J- Choroid
K- Retina
L- posterior chamber

82
Q

What is the main blood supply to the eye

A

Ophthalmic artery

83
Q

Ophthalmic artery is a branch of

A

Internal carotid artery

84
Q

What are the main branches of the ophthalmic artery

A

Central retinal artery
Posterior ciliary arteries
Anterior and posterior ethmoidal arteries

85
Q

What structure is supplied by the central retinal artery

A

Retina

86
Q

What structure is supplied by the posterior ciliary arteries

A

Optic nerve head

87
Q

What is the clinical significance of anterior and posterior ethmoidal arteries

A

They form the Kiesselbach’s plexus
If anterior nosebleed, it is likely to be due to anterior and posterior ethmoidal arteries

88
Q

What veins are responsible for most venous drainage of the eye

A

Superior and inferior ophthalmic vein

89
Q

The inferior ophthalmic vein drains into

A

Superior ophthalmic vein

90
Q

The superior ophthalmic vein drains into

A

Cavernous sinus

91
Q

How does cavernous sinus exit the skull

A

through superior orbital fissure

92
Q

What’s the vein that drains the retina

A

central retinal vein

93
Q

Name A-F

A

A- anterior and posterior ethmoidal arteryes
B- ciliary arteries
C- Ophthalmic artery
D- internal carotid artery
E- central retinal artery
F- central retinal vein

94
Q

Name A-E

A

A- Maxillary sinus
B- Inferior ophthalmic vein
C- Cavernous sinus
D- Superior ophthalmic vein
E- facial vein

95
Q

Describe the course of sympathetic innervation of the body

A
  1. passes down the spinal cord
  2. exits the spinal cord with T1-L2 spinal nerves and enter the sympathetic chains
  3. travel along the sympathetic chain to reach the desired level
  4. pass into anterior and posterior rami
  5. then pass into splanchnic nerves to reach the organs
96
Q

How do sympathetic innervations reach the head and neck

A
  1. the nerve fibres exit in T1 and ascend within the sympathetic chain
  2. Synapses at superior cervical ganglion
  3. post synaptic axons pass onto the surface of internal and external carotid arteries
  4. so that these axons follow the arteries up to the organs of the head
97
Q

Where do the sympathetic axons for head and neck synapse

A

Superior cervical ganglion

98
Q

Which artery does sympathetic axons follow in order to supply the eye

A

ophthalmic artery

99
Q

How do parasympathetic axons leave the CNS

A

via
- CN III oculomotor
- CN VII facial
- CN IX glossopharyngeal
- CN X vagus
- spinal nerves

100
Q

Parasympathetic fibres to the orbit synapses at

A

Ciliary ganglion

101
Q

What other axon fibres travel through the ciliary ganglion. Do they synapse there

A

General sensory
Sympathetic
No, they do not synapse there

101
Q

Which nerve supplies the parasympathetic fibres to the orbit

A

CN III

102
Q

Where is the ciliary ganglion located at

A

Between the optic nerve and lateral rectus muscle

103
Q

Describe the sensory innervation of the face

A

By CN V trigeminal nerve
CN V1
- upper eyelid and above
- cornea
- conjunctiva
CN V2
- lower eyelid to upper lips
CN V3
- lower lips to chin

104
Q

Describe the nerves involved in the blink reflex

A
  1. sensory action potentials produced by the cornea sent to CN V1
  2. CN V1 travels to the trigeminal ganglion then along the trigeminal nerve to CNS
  3. CNS connects CN V1 with CN VII (which innervates the orbicularis oculi muscle)
  4. Impulse sent to CN VII to stimulate contraction of orbicularis oculi muscle
105
Q

Describe the pupillary light reflex

A
  1. light is shine on one eye
  2. this generates action potential that is sent to both pretectal nuclei in the brain
  3. which stimulates another 2 nuclei (oculomotor nuclei)
  4. those 2 nuclei then send action potentials along the CN III (parasympathetic) to the sphincter papillae muscle to constrict both pupils = consensual light reflex
106
Q

Describe the lacrimation reflex

A
  1. sensory stimuli triggers action potentials to be sent along CN V1 lacrimal nerve
  2. action potentials travel to the CNS then sent to parasympathetic fibres originating from CN VII to trigger lacrimation
107
Q

Describe the lens accommodation reflex

A

To focus on far objects
- suspensory ligaments tighten to flatten the lens

To focus on near objects
- parasympathetic
- suspensory ligaments relax to curve the lens

108
Q

What is the vestibule-ocular reflex

A

Reflex that turns the eyes in the opposite direction to a head movement to stabilise gaze on an object during head movement