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Opthalmology > Anatomy > Flashcards

Anatomy Flashcards

1
Q

What is the white sclera covered by?

A

conjunctiva

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2
Q

What is it the iris covered by?

A

cornea

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3
Q

what is the limbus?

A

the corneoscleral junction

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4
Q

where is the lacrimal gland found in relation to the eye?

ii. why is this important?

A

the superolateral - found in the fossa for the lacrimal gland

ii. So the lacrimal fluid washes over the eye to the lacrimal lake

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5
Q

what is the dark circle of the eye called?

A

pupil

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6
Q

the pupils and iris of both eyes should be the same size true or false?

A

true

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7
Q

What is the orbit?

A

the bony cavity which houses the eye

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8
Q

How many bones make up the orbit?

A

7

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9
Q

Names the bones which make up the orbit.

A

Superficial bones:

Frontal bone (superior)

Zygomatic bone (lateral)

Maxilla bone ( inferior medial)

Deeper bones:

Sphenoid bone

Ethmoid bone

Lacrimal bone

Palatine bone

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10
Q

where are the orbital plates found?

A

Frontal bone

Ethmoid bone - more susceptible to fractures as they are thin walled plates

Maxilla bone - more susceptible to fractures as they are thin walled plates

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11
Q

Where is the optic canal?

A

Postero medially in the optic

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12
Q

what is the role of the optic canal?

A

Gap to allow the optic nerve and opthalmic artery to enter the orbit

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13
Q

Where is the superior orbital fissure located?

ii. what is its role?

A

between the greater and lesser wings of the sphenoid bones

ii. where cranial nerve 3,4 and 6 pass into the orbit

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14
Q

where is the supraorbital notch/foramen found?

ii. what is its role?

A

frontal bone

ii. allows supraorbital neurovascular bundle to enter the orbit

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15
Q

where is the infraorbital foramen found?

ii. what is its role?

A

maxilla bone

ii. allows infraorbital neurovascular bundle to enter the orbit

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16
Q

what cranial nerve is the supraorbital nerve a branch of?

A

The ophthalmic division of the trigeminal nerve

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17
Q

What cranial nerve is the infraorbital nerve a branch of?

A

Maxillary division of the trigeminal nerve

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18
Q

What is the shape of the orbit?

A

pyramidal shape

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19
Q

where is the apex of the orbit located?

A

posteriorly at the optic canal

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20
Q

where is the base of the orbit located?

A

anteriorly (superiorly)

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21
Q

what does the base of the orbit consist of?

A

The orbital rim:

lateral margin

inferior margin

medial margin

superior margin

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22
Q

compare the axis of the eyeball and orbit

A

eyeball axis - anterior

Orbit axis - anterolateral

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23
Q

what does a blowout fracture refer to?

A

medial wall and orbital floor fracture

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24
Q

where are the sutures in the orbit found?

A

frontal and zygomatic bone

zygomatic bone and maxilla bone

frontal bone and maxilla bone

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25
Q

what is the most external structure of the eye lid?

A

orbicularis oculi muscle

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26
Q

what type of muscle is the orbicularis oculi?

A

sphincter muscle

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27
Q

what are the two parts of the orbicularis oculi?

A

Orbital part - responsible for tight squeezing shut of eyes

palpebral part - inner part lies directly on the eye. Responsible for gentle closing of eyes

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28
Q

Which nerve innervates the orbicularis oculi muscle?

A

CN VII

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29
Q

what do the deeper structures of the eye lid consist of?

A

Tarsus - eye lid’s fibroskeleton

There is a inferior and superior tarsus

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30
Q

what are the ligaments found in the eye lid?

A

lateral palpebral

medial palpebral

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31
Q

what is the orbital septum

A

tough layer of connective tissue that holds the orbit components in place

separates superficial and deep parts of orbit. Thereby preventing spread of infection

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32
Q

where is the tendon of LPS?

A

found superiorly on the deeper layer of the eyelid

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33
Q

What is the LPS?

A

Levator palpebrae Superioris muscle

it attaches to the superior tarsus and skin of the eye lid via the tendon of LPS

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34
Q

what is the role of the LPS?

A

it pulls up the upper eye lid

it is a skeletal muscle

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35
Q

what is the smooth muscle of the LPS called?

ii. how does it carry out its role?

A

superior tarsus muscle (mueller’s muscle) - helps open eyes really wide when required

ii. It is a smooth muscle so has sympathetic innervation

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36
Q

Where is the tarsal gland found?

A

tarsus

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37
Q

what is the role of the tarsal glands?

A

secretes lipids which line the eye lid preventing overflow of tears or lacrimal fluid

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38
Q

which nerve innervates the lacrimal gland to produce lacrimal fluid?

A

CN VII

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39
Q

what happens to lacrimal fluid as you blink?

A

pushes lacrimal fluid to medial angle

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40
Q

where does the lacrimal fluid end up in the medial angle?

A

lacrimal lake

then it is needs to pass into the canaliculi

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41
Q

How does the lacrimal fluid enter the two canaliculi

A

via the two lacrimal puncta ( one in the upper and one in the lower eyelids)

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42
Q

Where does the lacrimal fluid move to once its entered the canaliculi?

A

the lacrimal sac - this is this the first part of the nasolacrimal duct

passes down the nasolacrimal duct

eventually ends up at the inferior meatus

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43
Q

what are the 7 extraocular muscles?

A

4 rectus muscles -all originate from common tendinous ring. all then insert onto sclera

  1. superior rectus
  2. Inferior rectus
  3. Medial rectus
  4. Lateral rectus

2 oblique muscles: both insert onto sclera

  1. Superior oblique - passes through the trochlea
  2. Inferior oblique
  3. Levator palpebrae superioris
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44
Q

Where does the superior oblique originate from?

A

sphenoid bone

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45
Q

where does the inferior oblique originate from?

A

orbital plate of maxilla

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46
Q

Where does the LPS originate from ?

A

lesser wing of sphenoid

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47
Q

where does the LPS attach to?

A

skin and tarsus of superior eyelid

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48
Q

What is the innervation of the Extraocular muscles?

A

THINK: LR6 SO4 AO3

LR6:

Lateral rectus - CN VI (abducent nerve)

SO4:

Superior oblique - CN IV ( trochlear nerve)

AO3:

All others - CN III (oculomotor nerve)

49
Q

what is the cornea?

A

clear part of the anterior eye

it is continuous with the sclera. However it is more convex

50
Q

The cornea is avascular true or false?

A

true

51
Q

what are the three layers of the eye?

A
  1. Outer - fibrous layer- has 2 parts

the sclera - muscle attachment

Cornea - 2/3 of refractive power

  1. middle layer - Uvea (vascular layer) - has 3 parts

iris - pupil diameter

Ciliary body - controls iris, shape of lens and secretion of aqueous humour

Choroid - nutrition and gas exchange. Darky reddy brown layer which makes up most of the vascular layer

  1. Inner layer - retina (photosensitive) - many parts
  2. main layers of retina:
  3. Photoreceptors - most posterior section
  4. Ganglion - where there is a synapse between photoreceptors and axons of the ganglion cells
  5. Axons of the ganglion cells - most anterior section
52
Q

What does the anterior segment of the eye consist of?

A

Everything in front of the lens

It is divided into:

Anterior chamber - between cornea and iris

and

Posterior chamber - between iris and suspensory ligaments

53
Q

What does the posterior segment of the eye consist of?

A

Behind lens - makes up 2/3 of the eye

Contains the vitreous body;

vitreous humour

vitreous body common location for floaters

54
Q

what is the iridocorneal angle?

A

angle between the iris and cornea

this is the angle which is referred to in “open angle” and closed angle” glaucoma

55
Q

Discuss the circulation of the aqueous humour

A
  1. Ciliary body consists of smooth muscle and blood vessels. It is here where the ciliary processes secrete aqueous
  2. Aqueous circulates within the posterior chamber and nourishes the lens
  3. The Aqueous then passes through the pupil into the anterior chamber and nourishes the cornea.
  4. The Aqueous reabsorbed into scleral venous sinus (canal of schlemm) at the iridocorneal angle
56
Q

What is the arterial supply of the eye?

A

ophthalmic artery - branch of the internal carotid - supplies most of the anatomical structures in the eye

Infraorbital artery - branch of the external carotid - supplies some structures in the floor of the orbit

57
Q

How does the internal carotid artery enter the cranial cavity?

A

passes through the cranial canal

it is here where it ophthalmic artery branches off

58
Q

How does the ophthalmic artery enter the orbital cavity?

A

via the optic canal

59
Q

what are the branches of ophthalmic artery?

A

ciliary arteries - long and short

central artery of the retina

60
Q

what do ciliary arteries supply blood to?

A

main supply to choroid

61
Q

what does the central artery of the retina supply blood to

A

pierces through the optic sheath and travels with optic nerve to reach retina

Only arterial supply for retina - it is an end artery

62
Q

What is an end artery?

A

An artery with insufficient anastomoses to maintain viability of the tissue supplied if arterial occlusion occurs.

63
Q

what is the name of the only vein which drains the retina?

A

central vein of the retina

64
Q

what are the main veins of the eye?

A

superior ophthalmic vein

Inferior ophthalmic vein - drains mainly into superior ophthalmic vein. Does drain into pterygoid plexus too

Facial vein - orbit also drains anteriorly into it

65
Q

where does the superior ophthalmic vein end up at?

A

Cavernous sinus via the superior orbital fissure

66
Q

what is the route of the central vein of the retina?

A

it either directly enters cavernous sinus or the superior ophthalmic nerve and then the cavernous sinus

67
Q

What does the danger triangle of the face refer to?

A

corners of the mouth to the bridge of the nose, including the nose and maxilla

many links of Superficial veins means spread of infection can be deadly

68
Q

what is the conjunctival fornix?

A

loose soft tissue lying at the junction between the palpebral conjunctiva (covering the inner surface of the eyelid) and the bulbar conjunctiva (covering the globe)

69
Q

Discuss how light is picked up in the retina.

A

Light hits the axons of the ganglion cells

passes through the axons and then the ganglion cells themselves

Light picked up by photoreceptors

70
Q

Discuss the structures of the Retina.

A

Fundus - posterior area where light is focused

it includes:

Optic disc - point of CN II formation.

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

called the blind spot - no photoreceptors at the optic disc

Macula

small oval type part of retina which has the greatest density of cones

Lateral to optic disc

Fovea

it is a depression which is the Centre of the macula

area of most acute vision

71
Q

What parts of the retina does light from the left visual field hit?

A

Nasal retina (inner side) of the Left eye

Temporal retina ( outer side) of the right eye

basically the right side of both eyes

72
Q

what parts of the retina does the light from the right visual field hit?

A

Temporal retina ( outer side) of the left eye

Nasal retina ( inner side) of the right eye

Basically the left side of both eyes

73
Q

which nerve receives information from the retina?

A

optic nerve (CN II)

74
Q

what occurs a the optic chiasma?

A

There is a crossover in information

All light from right visual field (temporal retina of the left eye and nasal retina of the right eye) meet and then are processed together at the LEFT primary visual cortex

All light from left visual field (temporal retina of the right eye and nasal retina of the left eye) meet and then are processed together at the RIGHT primary visual cortex

Think:

Light from temporal side stays on same side e.g. temporal retina of right eye has information processed at right primary visual cortex

75
Q

where is the light from objects in the lower visual field processed by?

A

upper part of the primary visual cortex

76
Q

Where is the light from objects in the upper visual field processed by?

A

Lower part of the primary visual cortex

77
Q

What is the lateral geniculate nucleus (LGN)

A

a relay centre in the thalamus for the visual pathway

78
Q

what are the axis of the eye?

A
  1. Vertical axis:

Abduction/adduction

  1. Transverse axis:

elevation/depression

  1. Anteroposterior axis:

Intorsion/extorsion

79
Q

Which extraocular muscles do not have secondary movements?

A

Medial rectus

Lateral rectus

80
Q

what are the primary movements of the extraocular muscles?

A

Superior rectus - contraction = elevation

Inferior rectus - contraction = depression

Superior oblique - contraction = depression

Inferior oblique - contraction = elevation

Lateral rectus - contraction = abduction

Medial rectus - contraction = adduction

81
Q

How do you test movements of individual muscles of the eye?

A

Line up the gaze to plane of muscles being tested

this isolates muscle movement

82
Q

when the eye has abducted what is the only movement the eye can do when the superior rectus contracts?

A

elevate

Innervated by CN III

83
Q

when the eye has abducted what is the only movement the eye can do when the inferior rectus contracts?

A

depress

innervated by CN III

84
Q

when the eye has adducted what is the only movement the eye can do when the superior oblique contracts?

A

Depress

Innervated by CN III

85
Q

when the eye has adducted what is the only movement the eye can do when the inferior oblique contracts?

A

Elevate

innervated by CN IV

86
Q

What does Pure elevation refer to?

A

both Superior rectus and inferior oblique contract to elevate eyes

However they are antagonists as rotators - they cancel each other out so only elevation occurs

87
Q

What does pure depression refer to?

A

Superior oblique and inferior rectus contract to depress eyes

However they are antagonists as adductors/abductors- they cancel each other out so only depression occurs

88
Q

What are the yoke muscles?

A

contralaterally paired extraocular muscles that work synergistically to direct the gaze in a given direction. For example, in directing the gaze to the right, the right lateral rectus and left medial rectus operate together as yoke muscles

89
Q

Give examples of organs in the head and neck which have autonomic innervation.

A
  1. Skin - sympathetic innervation of arterioles, sweat glands and arrector muscles
  2. Eyes - smooth muscle of iris (pupil diameter
    smooth muscle of ciliary body associated with
    the lens
  3. Lacrimal glands - lacrimal fluid production
  4. Salivary glands - saliva production
90
Q

what is the sympathetic innervation route for orbit and eyeball?

A

presynaptic

  1. originates from autonomic centres in the brain
  2. Passes down spinal cord
  3. Exits spinal cord with T1 spinal nerve
  4. Travel up within the sympathetic chain where it synapses in superior cervical sympathetic ganglion

postsynaptic

  1. Enters internal and external carotid nerves
  2. Pass onto surface of the internal and external carotid arteries
  3. Carried to the organs of the had of the surface of the branches of these arteries
  4. Ophthalmic artery carries sympathetic axons into the orbit
91
Q

what is the common sympathetic innervation route for all organs?

A
  1. originates from autonomic centres in the brain
  2. Passes down spinal cord
  3. Exits spinal cord with T1- L2 spinal nerves
  4. travel to sympathetic chains running the length of vertebral column
  5. Pass into all spinal nerves (anterior and posterior rami)
  6. Pass into splanchnic nerves to eventually supply organs
92
Q

what is the common parasympathetic innervation route for all organs?

A
  1. All parasympathetic axons leave the CNS via cranial nerves III, VII, IX and X and via sacral spinal nerves
  2. Craniosacral outflow
  3. Internal organs, not body wall:
    i. Parasympathetic ganglia in head - to eye, lacrimal gland salivary glands
    ii. Vagus nerve supplies rgans of the neck, chest and abdomen as far as the
    iii. Sacral spinal nerves supply parasympathetic axons to the hindgut, pelvis and perineum
93
Q

where is the ciliary ganglion found?

A

in the bony orbit

94
Q

what is the ciliary ganglion?

A

parasympathetic ganglion - carries fibres from CN III

95
Q

what is the parasympathetic route of CNIII to the eye?

A
  1. connects with CNS at junction of midbrain and pons
  2. Passes through cavernous sinus
  3. exits via superior orbital fissure
  4. Somatic motor to majority of extraocular muscles
  5. Presynaptic parasympathetic axons to the ciliary ganglion
  6. splits into 2 divisions: superior and inferior
96
Q

what is the meninges?

A

protective coverings of the brain and spinal cord?

97
Q

What are the three layers of the meninges?

A
  1. Dura mater - sensory supply from CN V
    encloses dural venous sinuses via its two layers

the two layers:

i. Periosteum layer
ii. Meningeal layer
2. Arachnoid mater - contains arachnoid granulations

subarachnoid space - contains CSF and blood vessels

  1. Pia mater - adheres to brain ( follows the grooves of the brain)
98
Q

where is the subarachnoid space?

A

between the arachnoid mater and pia mater

99
Q

how do you access the CSF?

A

lumbar puncture at L3/4 disc level

or

Lumbar puncture at L4/5 IV disc levels

100
Q

When does the subarachnoid space end?

A

inferiorly at vertebral space level S2

101
Q

How many ventricles in the brain are there?

A

4

Left lateral ventricle

right lateral ventricle

Midline 3rd ventricle

midline 4th ventricle

102
Q

what is the circulation of CSF?

A
  1. secreted by the choroid plexus
  2. the CFS passes into the right and left lateral ventricles
  3. and then passes down into the 3rd ventricle
  4. then through the cerebral aqueduct it enters the 4th ventricle
  5. The CSF passes mainly into the subarachnoid space but some passes into the central canal of the spinal cord
  6. It is then reabsorbed into the dural venous sinuses via the arachnoid granulations
103
Q

what is the choroid plexus?

A

epithelium/ modified pia located in the lateral and third ventricles where CSF is produced

104
Q

in which ganglion do sympathetic fibres traveling to the head and neck synapse?

A

superior cervical ganglion

105
Q

postsynaptic sympathetic fibres reach the orbit by travelling on the surface of which artery?

A

ophthalmic

106
Q

which parasympathetic ganglia are associated with the orbit?

A

Ciliary - more associated with the eyeball

pterygopalatine - more associated with the lacrimal gland

107
Q

which parts of the face does the CN V1 innervate? (ophthalmic)

ii. which type of innervation is this?

A

upper eyelid

cornea

conjunctiva

ii. sensory

108
Q

Which parts of the face does CN V2 innervate?
(maxillary)

ii. which type of innervation is this?

A

Skin of the lower eyelid

skin over the maxilla

ii. Sensory

109
Q

which parts of the face does CN V3 innervate? (mandibular)

ii. which type of innervation is this?

A

skin over the mandible and TMJ - except for the angle of mandible

ii. mainly sensory but some motor - motor mainly for muscles involved in mastication

110
Q

Discuss the corneal reflex (blink)

A

sensory (afferent) limb:

action potentials conducted from cornea via CN V1 branches to the trigeminal nerve then along the CN V to the pons

Central:

Central CNS connections between CNV and CNVII act as synapse

motor (efferent) limb:

Action potentials conducted via CN VII to the eyelid part of the orbicularis oculi

111
Q

what are the 6 main autonomic reflexes of the eye?

A

Wide eye opening of fight or flight

Pupillary light reflex

Accommodation reflex

Lacrimation reflex

vestibulo-ocular reflex

Oculocardiac reflex

112
Q

What is the vestibulo-ocular reflex?

A

Turns the eyes in the opposite direction to a head movement

this stabilises gaze on an object while the head moves

113
Q

what CNS connections are involved in the vestibulo-ocular reflex?

A

connections occur between:

CN III

CN IV

CN VI

CN VIII

114
Q

What is the oculocardiac reflex?

A

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

115
Q

what CNS connections are involved in the oculocardiac reflex?

A

connections occur between:

CN V1

CN X

116
Q

Give example of Sympathetic autonomic reflexes.

A

Eyes open wider

Get more light into eyes

focus on far objects

more emotional - more lacrimation

117
Q

Give example of parasympathetic autonomic reflexes.

A

Get less light into eye - when asleep

focus on near objects

reflex lacrimation - if foreign body is on eye

118
Q

what is Mueller’s muscle?

A

it is the superior tarsal muscle which is a part of the LPS

it is a smooth muscle which innervated by the sympathetic pathway

it helps elevate the eyelid by 2mm - it is involve in the autonomic reflex to open the eyelid

Opthalmology (3 decks)

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