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Opthalmology > Anatomy > Flashcards

Anatomy Flashcards

1
Q

What makes us the uvea

A

Iris
Ciliary body
Choroid

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2
Q

Describe the function of rod cells

A

They are sensitive to low levels of light

Used mainly in night vision and peripheral vision

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3
Q

Describe the function of cone cells

A

Used for detailed and colour vision

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4
Q

What is the macula

A

Area of the retina with the highest concentration of cones

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5
Q

In a retinal image the thicker vessels are arteries - true or false

A

FALSE - they are veins

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6
Q

Name the extraocular muscles

A

Superior. inferior, lateral and medial rectus

Superior and inferior oblique

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7
Q

Which cranial nerves help with control of the eye

A 
2 - optic 
3 - oculomotor 
4- trochlear 
5- trigeminal 
6- abducens 
7 - facial
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8
Q

Which cranial nerves are involved in the blink reflex

A

Trigeminal - efferent part

Facial - afferent part

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9
Q

What is emmetropia

A

Normal vision

no refractive error in eye

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10
Q

What is hypermetropia

A

Long sightedness
The eyes are smaller than average so light is focussed behind the retina
Will need positive lenses to bring the light forward to retina

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11
Q

What is myopia

A

Short sightedness
Larger than average eyes so light is focussed in front of retina
Needs negative lenses to move focus back

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12
Q

What is presbyopia

A

lens gradually stiffens with age (usually starts around 40)

Can’t change shape to adjust focus

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13
Q

List the bones of the bony orbit

A 
Frontal bone 
Sphenoid bone 
Orbital plate of the ethmoid bone 
Zygomatic bone 
Maxilla 
Lacrimal
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14
Q

What passes through the optic canal

A

The optic nerve

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15
Q

What forms the edge of the bony orbit

A

The orbital rim and margin

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16
Q

Which bones of the bony orbit are most likely to fracture

A

Medial wall and inferior wall
(ethmoid, lacrimal)
Thin bones

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17
Q

What is an orbital blowout

A

Fracture of bones in the bony orbit - thinnest ones (medial wall and floor)
usually caused by a blow to the face
Can damage the infraorbital neurovascular bundle
Eyeball can be extruded

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18
Q

What passes through the infraorbital foramen

A

Infraorbital artery and nerve

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19
Q

What is the function of the eyelid

A

Protects the eyes

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20
Q

What do the eyelids contain

A

Tarsal plate - keeps shape
Glands - secrete lipids
Orbicularis oculi
LPS muscle

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21
Q

What is the function of the levator palpabri superiorus

A

Muscle that elevates the upper eyelid

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22
Q

What is ptosis

A

Closed eye

Indicator of a third nerve palsy

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23
Q

What is the function of the orbicularis occuli

A

Circular muscle that closes the eye when it contracts

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24
Q

What is the function of the conjunctiva

A

A defensive barrier that covers the eye

Reflects back from eye to inner surface of eyelid

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25
Q

What is the cornea

A

The clear part of the eye that we look through

Responsible for refraction - lets light into the eye and focuses it onto the retina

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26
Q

What nerve supplies the lacrimal gland

A

CN VII - facial nerve

Parasympathetic supply

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27
Q

Describe how tears are formed

A

Produced in the lacrimal gland
Blinking washes tears over eye
They are pushed towards medial angle
Drain into the lacrimal puncta then the canaliculi
Will reach the lacrimal sac and eventually down the nasolacrimal duct and out the nose

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28
Q

What makes up the fibrous outer layer of the eye

A

sclera and cornea

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29
Q

What is the function of the iris

A

Controls diameter of pupil

It is a coloured muscle!

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30
Q

What is the function of the ciliary body

A

Controls iris, shape of lens and secretion of aqueous humour

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31
Q

What is the function of the choroid

A

Nutrition and gas exchange

Sits behind the retina

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32
Q

Where is the anterior segment

A

In front of the lens

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33
Q

Describe the divisions of the anterior segment

A

Anterior and posterior chamber
Anterior is found between cornea and iris
Posterior is found between iris and suspensory ligaments

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34
Q

What is contained in the anterior segment of the eye

A

Aqueous humour

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35
Q

Where is the posterior segment located

A

Behind the lens

2/3 of the eye

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36
Q

What is contained in the posterior segment of the eye

A

Vitreous humour

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37
Q

What can an excess in aqueous fluid lead to

A

Glaucoma

Raises intraocular pressure

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38
Q

What secretes aqueous humour

A

Ciliary processes in the ciliary body

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39
Q

Describe the path of aqueous humour through the eye

A

Secreted in ciliary body
Circulates in the posterior chamber to nourish lens
Then passes through pupil to nourish cornea It is then reabsorbed into scleral venous sinus at the iridocorneal angle

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40
Q

What is the arterial supply to the eye

A

The ophthalmic arteries
It is a branch of the internal carotid artery

It branches itself into the ciliary arteries and the central artery of the retina

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41
Q

List the venous drainage of the eye

A

Superior ophthalmic vein
Inferior ophthalmic
Drain into the cavernous sinus
Also drains anteriorly to the facial veins

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42
Q

What is the danger triangle

A

Area across the nose and upper lip

If there is an abscess here it can drain backwards into the cavernous sinus and lead to sinus thrombosis

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43
Q

What is the fovea

A

centre of the macula
small depression
area of most acute vision

44
Q

What is the optic disc

A

Point of optic nerve formation
Where blood vessels and nerve enter/exit
Also has the blind spot

45
Q

List the layers of the retina from posterior to anterior

A

Photoreceptors
Ganglion cells
Axons of the ganglion

46
Q

Why is the optic disc the blind spot

A

There are no photoreceptors in the optic disc

47
Q

Where is light from the right visual field processed

A

Left primary visual cortex

Opposite is true

48
Q

Where is light from the lower visual field processed

A

Upper part of the primary visual cortex

Opposite is true

49
Q

What does the superior orbital muscle pass through

A

A pulley

The trochlear

50
Q

List the action of the recti eye muscles

A

lateral rectus – pulls eyeball laterally
medial rectus – pulls eyeball medially
superior rectus – up and in
inferior rectus - down and in

51
Q

List the actions of the oblique eye muscles

A

superior oblique – down and out

inferior oblique - up and out

52
Q

List the innervation to the eye muscles

A

Lateral rectus - abducens nerve (CN6)
Superior oblique - trochlear nerve (CN4)
Rest of the muscles are CN3 (oculomotor)

53
Q

What areas does CNV1 give sensory supply to

A

Upper eyelid
Cornea
Conjunctiva
Skin of the root, bridge and tip of the nose

54
Q

What areas does CNV2 give sensory supply to

A

Skin of the lower eyelid
Skin over the maxilla
Skin of the ala of the nose
Skin/mucosa of the upper lip

55
Q

What areas does CNV3 give sensory supply to

A

Skin over the mandible (except the angle) and temporomandibular joint

56
Q

Describe the sensory limb of the blink reflex

A

Action potential conducted from cornea via CNV1
Then to the trigeminal ganglion along CNV
To pons

57
Q

Describe the motor limb of the blink reflex

A

Action potentials conducted CNVII

To eyelid part of orbicularis oculi

58
Q

Describe the route of sympathetic axons

A

Thoracolumbar outflow
Leaves brain and passes down spinal cord
Exits spinal cord with T1-L2
Travel to the sympathetic chains
Pass into the spinal nerves via anterior and posterior rami
Pass into the splanchnic nerves to supply organs

59
Q

Which nerves synapse in the superior cervical ganglion

A

Presynaptic sympathetic axons from the CNS
Exit at T1 level and ascend in the sympathetic trunk
Synapse in the ganglion

60
Q

Describe the path of the post-synaptic neurons as they level the superior cervical ganglion

A

Enter the internal and external carotid nerves
Pass onto surface of the internal and external carotid arteries
Carried to the organs of the head with arteries

61
Q

What carries sympathetic nerves into the orbit

A

The ophthalmic artery

Delivers fibres to the eye itself

62
Q

How do parasympathetic axons leave the CNS

A

Via cranial nerves III, VII, IX and X
And the sacral spinal nerves
(Craniosacral outflow)

63
Q

Which structures in the orbit are supplied by parasympathetic nerves

A

Eye

Lacrimal glands

64
Q

Which parasympathetic nerve is responsible for changing the shape of the iris and lens

A

Fibres from CNIII

Oculomotor

65
Q

Describe the path of the oculomotor nerve

A

Leaves brain between the midline and pons
Passes through the cavernous sinus
Exits via the superior orbital fissure
Divides into superior and inferior division

66
Q

What does the superior division of the oculomotor nerve supply

A

Somatic motor innervation to the superior rectus and levator palpebrae superioris

67
Q

What does the inferior division of the oculomotor nerve supply

A

Somatic motor innervation to the medial and inferior rectus, the inferior oblique
Parasympathetic axons to the ciliary ganglion

68
Q

What are the functions of the ciliary nerves

A

Supply autonomic axons to the eye
Controls diameter of iris and shape of lens
Long nerves are sympathetic and somatic sensory (responsible for part of blink)
Short ciliary nerves have both sympathetic and parasympathetic fibres

69
Q

What occurs in the ciliary ganglion

A

Synapse of pre and post parasympathetic nerves

70
Q

List the sympathetic effects on the eye

A

Open eyes wider
Dilate pupils - get more light in
Focus lens on far objects
Emotional lacrimation - crying

71
Q

What is the vestibulo-ocular reflex

A

Eyes move the opposite way to head movement

Stabilizes gaze during head movement

72
Q

What is the oculocardiac reflex

A

Reflex bradycardia in response to tension on extraocular muscles or pressure on eye

73
Q

List the effects of the parasympathetic nerves on the eye

A

Allows orbicularis oculi to work
Constricts pupil - less light
Focus on near objects
Reflex lacrimation - wash away foreign bodies

74
Q

Describe the levator palpebrae superioris

A

Contains smooth and skeletal muscle
Supplied by oculomotor and sympathetic nerves
Responsible for opening the eye

75
Q

Why do our eyes open wide in the fight or flight response

A

Sympathetic nerves supplying the LPS are stimulated and the muscle contracts, opening the eye

76
Q

What is a mydriatic pupil

A

One that is non-physiologically enlarged

Can be done with chemicals or drugs

77
Q

What controls the diameter of the pupil

A

Dilator papillae fibres
Arranged radially around the iris - dilate pupil

Sphincter pupillae fibres constrict the pupil

78
Q

What is a non-physiologically constricted pupil called

A

Miotic pupil

Seen in Horner’s

79
Q

What is a pinpoint pupil a sign of

A

Opiate drug use

Serious pathological sign

80
Q

What is a fixed, dilated pupil a sign of

A

Serious pathology

Pathology of CN3

81
Q

What is the direct light reflex

A

Constriction of pupil in the eye when light is shone into it

82
Q

What is the consensual light reflex

A

Constriction of pupil when light is shone into the opposite eye

83
Q

Which nerves are involved in the pupillary light reflex

A

Sensory info travels up the optic nerve
CNS connection in midbrain
Effector/motor part is by the oculomotor nerve

84
Q

In the brain, which nuclei are involved in the light reflex

A

Pretectal nucleus - optic nerve synapses here

Edinger Westphal nucleus - passes signal to CN3

85
Q

When the ciliary muscle is relaxed what happens

A

Used for far vision
No parasympathetic input
Suspensory ligaments tighten and lens flattens out

86
Q

When the ciliary muscle is contracted what happens

A

Suspensory ligaments relax and the lens goes back to a spherical shape
Allows near vision
Uses parasympathetics

87
Q

A rounded lens bends more light -true or false

A

TRUE

88
Q

What is the accommodation reflex

A

Change in focus from far to near vision

To do this, the pupils constrict, there is bilateral convergence of eyes (cross eyed) and the lens relaxes

89
Q

What are basal tears

A

The tears that clean, hydrate and nourish the cornea

Contain lysozyme - kills bacteria

90
Q

What are reflex tears

A

Extra tears in response to mechanical or chemical stimulation
Afferent limb is CN V1 from cornea/conjunctiva (sensory)
Efferent limb is parasympathetic axons originating from CN VII (motor)

91
Q

What are the functions of the eyelid

A

Protects the cornea

Spreads the tear film over the eye

92
Q

Which muscle keeps the eye open unconsciously

A

Muller’s muscle

collection of muscle fibres within levator palpibrae superiorus that has sympathetic innervation

93
Q

Where is the mucous layer of the tear film produced

A

conjunctiva

94
Q

What is the function of the mucous layer of the tear film

A

Keeps the other layers stuck to the eye

95
Q

Where is the lipid layer of the tear film produced

A

By glands in the eyelids

96
Q

What is the function of the lipid layer of the tear film

A

Stops the aqueous phase from evaporating too quickly

97
Q

Where is the aqueous layer of the tear film produced

A

Lacrimal glands

98
Q

Which part of the eye is responsible for refraction

A

Cornea

99
Q

The shape of the cornea determines what

A

whether you need glasses or not

100
Q

What is the function of the lens

A

Accommodation = changes shape to allow you to look near or far

101
Q

The lens naturally sits in what shape

A

Sphere

102
Q

What supports the lens of the eye

A

Zoonules (suspensory ligaments)

103
Q

What is ametropia

A

When there is a refractive error present

Light is focused either in front or behind retina

104
Q

What is anisometropia

A

When there is a significant difference in the refractive power of each eye
Different prescription L and R

105
Q

What is an astigmatism

A

This is when the eye has different refractive powers across it as the eye is more rugby ball shaped
Treated with cylindrical lenses

Opthalmology (9 decks)

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