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Flashcards in Eye Deck (88):
1

Which bone makes up the roof of the orbit?

Orbital plate of the frontal bone

2

Which bone makes up the floor of the orbit?

The maxilla

3

Which structure is being indicated here?

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Supraorbital notch/foramen

4

Which structures are being indicated here?

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1. Optic canal

2. Superior orbital fissure

(Both part of sphenoid bone)

5

Which structures of which bone are indicated here?

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Infraorbital canal and foramen of maxilla

6

Which bone of the orbit is indicated in blue?

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Lacrimal

7

Which bone of the orbit is indicated in yellow?

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Orbital plate of ethmoid bone

8

Which structure protects the eye from a direct blow?

The orbital margins

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9

Which bones tend to fracture in an orbital blowout fracture and why?

Orbital plate of ethmoid bone (medial wall)

Maxilla (floor)

They are extremely thin - 0.5-1mm thick

 

10

How does a fractured zygoma tend to displace?

Tends to rotate medially to the floor of the orbit

11

Which structure is held within the infraorbital canal?

Infraorbital NVB

12

Which muscle makes up the 'sphincter' of the eye and what movement does it allow?

Obicularis oculi

Allows us to screw up the eyes

13

Which two ligaments attach the eyelid to the orbital rim?

Medial and lateral palpebral ligaments

14

Which structure is being indicated here and what is its function?

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Tendon of levator palpebrae superioris

Contains skeletal and smooth muscle to elevate the superior eyelid

15

Which structures are being indicated here?

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Superior and inferior tarsal plates

16

What is the orbital septum?

A sheet of fascia attaching to the peripery of the orbital rim

17

What does the orbital septum do?

Assists with preventing the spread of infection from superficial (periorbital cellulitis) to deep (orbital cellulitis)

18

What is the conjunctival fornix?

Where the conjunctiva is reflected off the sclera and onto the internal aspect of the eyelid

19

What is the name given to the orbital opening into the nasolacrimal duct?

Puncta

20

What is the name of the junction between the cornea and the sclera?

The limbus

21

What is the parasympathetic supply of the lacrimal gland?

CN VII

22

What is the name of the superior end of the nasolacrimal duct?

Lacrimal sac

23

Where should corneal reflections be seen normally?

Slightly medial i.e. nasal side of the pupil (as opposed to temporal side)

24

What are the two parts of the outer fibrous layer of the eye?

Sclera

Cornea

25

What is the function of the sclera?

Protects the eye

Provides attachment for the extraocular muscles

26

What is the function of the cornea?

Provides 2/3 of the eye's refractive power

27

What are the three parts of the uvea?

The iris

The ciliary body

The choroid

28

What is the vascular layer of the eye?

The uvea

29

What is the function of the ciliary body of the eye?

Control of the iris and the shape of the lens

Secretion of aqueous humour

30

What is the photosensitive layer of the eye?

The inner retina

31

What is the function of the choroid?

Nutrition and gaseous exchange for the other layers

32

Which is the 'vascular' layer of the eye?

Choroid

33

What is the vitreous body?

A structure in the posterior segment which holds a clear gel consisting of ~98% water that provides pressure to hold the retina in place

34

What is the anterior chamber?

The space containing aqueous humour between the cornea and the iris

35

What is the posterior chamber?

Contains the lens and aqueous (humour) and is located between the iris and the vitreous body

36

What is the function of the ciliary body?

Controls the refractive shape of the lens and the secretion of aqueous humour

37

What is the area of most acute vision in the eye?

The fovea centralis in the macula - contains the largest density of cones

38

What is the only vein that drains the retina?

Central vein of the retina

39

Which structures are being indicated here?

Q image thumb

A image thumb
40

How do the opthalmic veins drain the orbit?

Anteriorly: orbit drains into the facial vein

Posteriorly: inferior opthalmic vein drains mainly into superior opthalmic vein, and drains into the cavernous sinus

41

Through which structure does the superior opthalmic vein drain into the cavernous sinus?

Superior orbital fissure

42

What is the retinal blood supply provided by?

The central retinal artery

The central retinal vein

43

Which artery do the ciliary arteries branch from?

Opthalmic artery

44

What is the result of an occlusion of a retinal artery branch/branch retinal vein?

An area of visual loss corresponding to the area of ischaemia

45

What is the result of a complete interruption of flow to the central retinal artery or vein?

Monocular blindness

46

Which structure does the 'blind spot' of the visual field correspond to?

The optic disc

47

What are the three layers of the retina posterior - anterior?

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1. Photoreceptors

2. Ganglion cells

3. Axons of ganglion cells

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48

Where in the brain are the visual cortices?

In the occipital lobes

49

Where in the visual pathway does synapse occur?

Right and left sides of the thalamus

50

Does light picked up in the temporal retina cross over in the optic chiasm as the action potentials travel in the visual pathway?

No

51

Does light picked up in the nasal retina cross over at the optic chiasm as the action potential travels along the visual pathway?

Yes

52

Where do the rectus muscles of the eye all originate and insert?

They have a common origin - common tendinous ring attached to the bones surrounding the optic canal

All insert into the sclera just posterior to the cornea

53

What are the 7 extraocular muscles?

4 rectus - superior, inferior, lateral and medial

2 obliques - superior and inferior

Levator palpebrae superioris

54

What is the trochlea of the eye?

A fibrous structure used as a pulley by the superior oblique muscle of the eye

It attaches superomedially to the rim of the eye

55

What is the motor innervation to the extraocular muscles?

LR6  SO4  AO3

Lateral rectus - abducens

Superior oblique - trochlear

All others - oculomotor

56

Which muscle abducts the eye?

Lateral rectus

57

If a patient is asked to look to the left, which muscles in each eye are working?

Left eye - lateral rectus

Right eye - medial rectus

58

What movement of the eye does the inferior oblique provide?

Elevates from the aDDucted position

59

What movement of the eye does the superior oblique provide?

Depresses the eye from the aDDucted positon

60

Which muscles are working in each eye if the patient is asked to look left and upwards?

Left eye - lateral rectus and superior rectus

Right eye - medial rectus and inferior oblique

61

Which muscles are working if the patient is asked to look up?

Both eyes - superior rectus and inferior oblique

62

Which muscles are working if the patient is asked to look down?

Both eyes - inferior rectus and superior oblique

63

What is the general sensory nerve supply to the upper eyelid, the cornea, all the conjunctiva and the the skin of the root/bridge/tip of the nose?

Opthalmic nerve CN V1

64

What nerves are involved in the blink reflex?

Afferent: Cornea - V1 - V - pons

Efferent: VII - obicularis oculi

 

65

How does sympathetic innervation reach the orbit?

Sympathetic fibres exit the spinal cord at T1, and travel upwards to synapse in the superior cervical chain

Post synaptic fibres enter the external carotid nerve and internal carotid nerve, attached to the arteries

They are carried along the arteries to the orbit

66

What structures are being indicated here?

Q image thumb

A image thumb
67

What is the base of skull course of the oculomotor nerve?

Superior orbital fissure

68

Where does the oculomotor nerve connect with the CNS?

Junction between midbrain and pons

69

What is the function of the ciliary nerves?

Supply autonomic axons to the iris to alter diameter of pupil and to change refractive shape of lens

70

What structures are there in the ciliary ganglion?

Presynaptic fibes of CN III
Postsynaptic sympathetic fibres from the superior cervical ganglion

Postsynaptic fibres from the ciliary ganglion

General sensory fibres from the cornea and conjunctiva

71

What are the four autonomic relfexes of the eye?

Pupil dilation/constriction

Lacrimation

Maximal eyelid elevation

Focussing the lens

72

What is the vestibulo-ocular reflex?

Turns the eyes in the opposite direction to a head movement

73

What nerves are involved in the vestibulo-ocular reflex?

Vestibulocochlear VIII

Oculomotor III

 Trochlear IV
Abducens VI

74

What is the oculocardiac reflex?

Reflex bradycardia in response to pressure on the eye or tension on extra ocular muscles

75

Which nerves are involved in the oculocardiac reflex?

Opthalmic nerve V1

Vagus X

76

What changes to the eye does sympathetic innervation cause?

Open eyes wider

Pupil dilation

Focus on far objects

? emotional lacrimation

77

What changes to the eye does parasympathetic innervation cause?

Allow obicularis oculi to work

Allow less light into eye

Focus on near objects

Reflex lacrimation

78

What is a non-physiologically dilated pupil called?

A mydriatic pupil

79

Which muscle allows pupil dilation and what is its origin and insertion?

Dilator pupillae

Origin around the external circumference of the iris

Insertion around the internal circumference of the iris

 

80

Which muscle allows constriction of the pupil and where is it located?

Sphincter pupillae

Internal circumference of the iris

81

What is a non-physiologically constricted pupil known as?

A miotic pupil

82

What is the special sensory afferent limb of the light reflex?

Optic nerve CN II

83

What is the light reflex called in the stimulated eye and the other eye?

Stimulated - direct light reflex

Other - consensual light reflex

84

What is the motor limb of the light relfex?

Oculomotor CN VIII

85

Which structure connects the surface of the lens and the ciliary body?

Suspensory ligament of the lens

86

How does the ciliary body change the shape of the lens to allow the eye to focus on object in the distance?

Ciliary muscle relaxes

The suspensory ligament tightens, flattening the lens

No parasympathetic inneravation involved

87

How does the ciliary body change the refractory shape of the lens to allow focus on near objects?

Ciliary muscle contracts - parasympathetic innervation

Suspensory ligament relaxes and makes the lens spherical

88