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Year 2 - Ophthalmology (DP) > Anatomy > Flashcards

Flashcards in Anatomy Deck (133):
1

Which of the following form the superior wall (roof) of the bony orbit:
- Orbital part of frontal bone
- Ethmoid
- Front process of the zygomatic bone
- Maxilla
- Zygomatic and palatine bones
- Lesser wing of sphenoid
- Great wing of sphenoid
- Optic canal
- Inferior, medial and later orbital margins

Orbital part of frontal bone
AND
Lesser wing of sphenoid

2

Which of the following form the medial wall of the bony orbit:
- Orbital part of frontal bone
- Ethmoid
- Front process of the zygomatic bone
- Maxilla
- Zygomatic and palatine bones
- Lesser wing of sphenoid
- Great wing of sphenoid
- Optic canal
- Inferior, medial and later orbital margins

Ethmoid bone

3

Which of the following form the lateral wall of the bony orbit:
- Orbital part of frontal bone
- Ethmoid
- Front process of the zygomatic bone
- Maxilla
- Zygomatic and palatine bones
- Lesser wing of sphenoid
- Great wing of sphenoid
- Optic canal
- Inferior, medial and later orbital margins

Frontal process of zygomatic bone
AND
Greater wing of sphenoud

4

Which of the following form the inferior wall (floor) of the bony orbit:
- Orbital part of frontal bone
- Ethmoid
- Front process of the zygomatic bone
- Maxilla
- Zygomatic and palatine bones
- Lesser wing of sphenoid
- Great wing of sphenoid
- Optic canal
- Inferior, medial and later orbital margins

Maxilla
Zygomatic and palatine bones

5

Which of the following forms the apex of the bony orbit:
- Orbital part of frontal bone
- Ethmoid
- Front process of the zygomatic bone
- Maxilla
- Zygomatic and palatine bones
- Lesser wing of sphenoid
- Great wing of sphenoid
- Optic canal
- Inferior, medial and later orbital margins

Optic canal

6

Which of the following form the base of the bony orbit:
- Orbital part of frontal bone
- Ethmoid
- Front process of the zygomatic bone
- Maxilla
- Zygomatic and palatine bones
- Lesser wing of sphenoid
- Great wing of sphenoid
- Optic canal
- Inferior, medial and later orbital margins

Inferior, medial and lateral orbital margins

7

What protects the eye from direct blows?

Prominence of superior orbital margin

8

What parts of the bony orbit are commonly affected by an orbital blowout fracture and why?

Medial wall and floor:
- Very thin

9

What NVB can be damaged in optical trauma?

Infraorbital

10

What forms the external layer of the eyelids?

Orbicularis oculi
Orbital and palpebral parts

11

What forms the orbital septum?

Sheet of fascia

12

What do the tarsal glands secrete?

Lipids

13

What nerve causes lacrimal fluid to be produced?

CN VII (PNS)

14

What is the path of lacrimal fluid once it leaves the lacrimal gland?

Pushed towards medial angle
Drains through lacrinal puncta
Reaches inferior meatus

15

What is the approximate diameter of the eyeball?

25mm

16

What comprises the fibrous outer layer of the eye? What are their functions?

Sclera -> Muscle attachment
Cornea -> 2/3 of refractive power

17

What is the uvea? What forms the uvea? What are their functions?

Vascular middle layer
Iris -> pupillary diameter
Ciliary body:
- Controls iris
- Shape of lens
- Secretion of aqueous humour
Choroid -> Nutrition and gas exchange

18

What is the retina?

Photosensitive inner layer

19

Where is the anterior segment of the eye?

In front of the lens

20

What is the anterior segment of the eye composed of? Where are they located?

Anterior chamber -> Between cornea and iris
Posterior chamber -> Between iris and suspensory ligaments

21

Where is the posterior segment of the eye? How much of the eye does it make up and what does it contain?

Behind the lens
2/3 of eye
Contains vitreous body -> Vitreous humour

22

When aqueous humour is in the posterior chamber, what does it nourish?

Lens

23

When aqueous humour is the anterior chamber, what does it nourish?

Cornea

24

Through what does the aqueous humour pass to reach the anterior chamber?

Pupil

25

Where is the aqueous humour reabsorbed?

At iridocorneal angle (glaucoma):
-> Into scleral venous sinus
-> Canal of Schlemm

26

Where is the macula located in relation to the optic disc on fundoscopy?

Laterally

27

What is the macula?

Highest concentration of cones

28

What is the diameter of the fovea?

1.5mm

29

What is the optic disc?

Point of CN II formation
Point of entry/exit of vessels and CN II

30

What visual loss is expected in a retinal artery branch of retinal vein interruption?

Loss in an area of the visual filed

31

What visual loss is expected in an interruption of flow through a central artery or vein?

Monocular blindness

32

What are the layers of the retina (from posterior to anterior)?

Photoreceptors
Ganglion cells
Axons of ganglion cells

33

Where do the retinal arteries and veins lie in relation to the retina?

Anteriorly

34

Where is light from the right visual field processed?

Left primary visual cortex

35

Where is light from objects in the lower visual field processed?

Upper part of primary visual cortex

36

Where does the retinal arterial supply derive from?

Ophthalmic artery (from internal carotid artery)

37

What are the important branches of the ophthalmic artery in the eye?

Central artery of the retina (end-artery)
Ciliary arteries

38

What are the 4 rectus muscles?

Superior (SR)
Inferior (IR)
Medial (MR)
Lateral (LR)

39

Where do the 4 rectus muscles originate and insert?

Origin -> Common tendinous ring
Insertion -> Sclera

40

What are the two oblique muscles and where do they insert?

Superior (SO)
Inferior (IO)
Insert on to sclera

41

What muscle lifts the upper eyelid?

Levator palpebrae superioris

42

What is the somatic motor innervation of the 7 extraocular skeletal muscles?

LR6 SO4 AO3
Lateral rectus -> CN VI
Superior oblique -> CN IV
All others -> CN III

43

Why is CN VI prone to damage?

Has a very long course from brainstem to eye so is vulnerable to trauma

44

What eye movements does the vertical axis allow?

Abduction and adduction

45

What eye movements does the transverse axis allow?

Elevation and depression

46

What eye movements does the AP axis allow?

Intorsion and extorsion

47

What two axes are important in the direction of gaze?

Vertical axis and Transverse axis

48

Where is the apex of orbit located?

Medially

49

What two extraocular muscles do not have secondary movements?

Medial and lateral rectus

50

What function does the lateral rectus have?

Abducts eye

51

When the eye is in abduction, what is the only movement the superior rectus can carry out?

Elevation

52

When the eye is in abduction, what is the only movement the inferior rectus can carry out?

Depression

53

What function does the medial rectus have?

Adducts eye

54

What line of gaze does the lateral rectus bring the eye into?

Superior rectus
Inferior rectus

55

What line of gaze does the medial rectus bring the eye into?

Superior oblique
Inferior oblique

56

When the eye is in adduction, what is the only movement the inferior oblique can carry out?

Elevation

57

When the eye is in abduction, what is the only movement the superior oblique can carry out?

Depression

58

What muscles are required for pure eye elevation? How do they work in doing so?

Superior rectus and inferior oblique:
- Synergistic elevation
- Antagonise the rotation of each other

59

What muscles are required for pure eye depression? How do they work in doing so?

Superior oblique and Inferior rectus:
- Synergistic depression
- Antagonise abduction and abduction
- Antagonise intorsion and extorsion

60

What direction does the fractured zygoma tend to rotate?

Medially towards floor of orbit

61

Where does the supensory ligament attach to the zygoma?

Laterally

62

What can result in fractures to the zygoma?

The eye can lower -> Diplopia

63

What happens if the infraorbital NVB is damaged?

Sensory defect of the skin

64

Which of the following does CN V1 not supply:
- Upper eyelid
- Cornea
- All of conjunctiva
- Lower eyelid
- Skin of nose root/bridge/tip

Lower eyelid

65

Which of the following does CN V2 not supply:
- Lower eyelid
- Skin over maxilla
- Nose tip
- Skin of ala
- Skin/mucosa of upper lip

Nose tip

66

Which of the following does CN V3 not supply:
- Skin over mandible
- Skin over TMJ
- Angle of mandible

Angle of mandible:
- Supplied by C2 and C3

67

What is the afferent (sensory) pathway of the blink/corneal reflex?

CN V1 -> Trigeminal ganglion -> CN V -> Pons

68

What is the efferent (motor) pathway of the blink/corneal reflex?

CN VII -> Eyelid part of orbicularis oculi

69

Put the following steps of the presynaptic axon route from the CNS (in the SNS):
- Ascend in sympathetic trunk
- Exit in T1 spinal nerve
- Descend in spinal cord
- Synapse in superior cervical ganglion

1. Descend in spinal cord
2. Exit in T1 spinal nerve
3. Ascend in sympathetic trunk
4. Synapse in superior cervical ganglion

70

What two nerves do the postsynaptic SNS axons enter?

Internal and External carotid nerves

71

What do the postsynaptic SNS axons run along?

Internal and External carotid arteries

72

Along what artery are the postsynaptic SNS fibres caried into the orbit?

Ophthalmic artery (intracranial branch of internal carotid artery)

73

What ganglia fuse to form the stellate ganglion?

Inferior cervical
1st thoracic

74

What does the PSN outflow of CN III supply?

Eye

75

What does the PSN outflow of CN VII supply?

Lacrimal gland
Submandibular and sublingual glands

76

What does the PSN outflow of CN IX supply?

Parotid gland

77

What does the PSN outflow of CN X supply?

Neck
Chest
Abdomen (up to midgut)

78

What muscles does CN III supply?

SR, MR, IR and IO
Levator palpebrae superioris

79

What ganglion do the PNS fibres in CN III go to?

Ciliary ganglion

80

Where does CN III connect to the CNS?

Near the midline:
- At junction of midbrain and pons

81

What muscles does the superior branch of CN III supply?

SR
LPS

82

What muscles does the inferior branch of CN III supply?

MR
IR
IO
Ciliary ganglion

83

What fibres are contained in the long ciliary nerve and what does it form?

SNS and sensory
1st part of afferent limb of blink reflex

84

What fibres are contained in the short ciliary nerve?

Sensory
PNS
SNS

85

What are the six autonomic reflexs of the eye?

Maximal eyelid elevation (during fight or flight)
Pupillary light reflex
Accommodation reflex
Lacrimation
Vestibulo-ocular reflex
Oculocardiac reflex

86

What pressures on the eye cause bradycardia?

Tension on extraocular muscles
Pressure on globe

87

What CNS connections control the vestibulo-ocular reflex?

CN VIII and CNs III, IV + VI

88

What CNS connections control the oculocardiac reflex?

CN V1 and CN X

89

What are the sympathetic functions on the eye?

Opens eye wider
Gets more light into eyes
Focus on far objects
Emotional lacrimation

90

What are the parasympathetic function on the eye?

Allow orbicularis oculi to work
Get less light into eye
Focus on near objects
Reflex lacrimation

91

What is a mydriatic pupil?

Non-physiologically enlarged pupil

92

What drugs can induce mydriasis?

Tropicamide
Phenylephrine

93

What muscles control pupil dilation?

Dilator pupillae

94

How are the muscles controlling pupil dilation arranged? What are their origins and insertions?

Radially
Origin:
- Fixed
- Around external iris circumference
Insertion:
- Mobile
- Around internal iris circumference

95

What is a miotic pupil

A non-physiologically consticted pupil

96

How is Horner's syndrome tested?

Cocaine eye drops

97

What can cause a fixed 'pin-point' pupil?

Opiate drug abuse

98

What can cause a 'fixed-dilated' ('blown') pupil?

CN III pathology:
- Inhibition of pupillary constriction action of PSN

99

Where are the sphincter pupillae fibres arranged around?

Internal iris circumference

100

In the pupillary light reflex, on what side is the special sensory afferent limb?

Ipsilateral side (of light source) (CN II)

101

In the pupillary light reflex, on what side is the special motor efferent limb?

Bilateral (CN III)

102

What are the first neurons in the pupillary light reflex? What is their route?

Retinal ganglion cells:
- Pass via ipsilateral CN II
- Decussate in optic chiasm
- Synapse in pretectal nucleus in midbrain

103

What is the route of the second neurons in the pupillary light reflex?

Located totally in midbrain
Connect pretectal nucleus to the synpase in the Edinger Westphal nucelus:
- Location of CN III PSN cell bodies

104

What is the route of the third neurons in the pupillary light reflex?

Pass from EW nucleus:
- Via CN III
- Inferior branch -> Synapses in ciliary ganglion

105

What is the route of the fourth neurons in the pupillary light reflex?

Course in the short ciliary nerves
-> Sphincter pupillae muscles

106

What happens when looking at a far object?

Ciliary muscle relaxes (No PSN stimulation)
Ligaments tighten
Lens flattens

107

What happens when looking at a near object?

CIliary muscle contracts (PSN stimulation)
Ligaments relax
Lens becomes more spherical

108

What are the three components of the accommodation reflex? What nerves do these functions test?

1. Bilateal pupillary constriction (CN III)
2. Bilateral convergence (CN III):
- Medial rotation of both eyes
3. Bilateral relaxation of lens (CN III):
- Ciliary muscle contraction

109

What enzyme is contained in basal tears?

Lysozyme:
- Hydrolyses bacterial cell walls

110

What is the afferent and efferent limbs of reflex lacrimation?

Afferent -> CN V1
Efferent -> CN VII

111

What is the indirect pupillary reflex?

When light is shone on one eye the contralateral pupil constricts

112

If the contralateral pupil does not constrict (as part of indirect pupillary reflex), what does this indicate?

Defect in efferent pathway of contralateral pupil

113

What does the swinging light test test for?

Relative afferent pupillary defect

114

Explain how the swinging light test works?

1. Shine light into affected eye (one with a prechiasmal lesion) -> Both pupils constrict (to ~4mm)
2. Shine light into normal eye -> More constriction (to ~2mm)
3. Shine light into affected eye -> Relative dilation (back to ~4mm)

115

What contributes to the ICP?

Brain
Blood
CSF

116

What is the Monro-Kellie Hypothesis?

The cranial compartment is incompressible and has a fixed volume.
Its contents create a volume equilibrium.
Therefore an increase in the volume of one cranial constituent must result in a decrease in another.

117

What visual problems can result due to raised ICP?

Transient blurred vision
Diplopia
Loss of vision
Papilloedema
Pupillary changes

118

What are the meninges (from external to internal)?

Dura
Arachnoid
Pia

119

What is the sensory supply to the dura mater?

CN V

120

What does the dura mater enclose?

Dural venous sinuses

121

What does the arachnoid mater contain?

Arachnoid granulations

122

What is in the subarachnoid space?

Circulation CSF and blood vessels

123

What does the pia adhere to?

Brain
Vessels and nerves entering/leaving cranium

124

Where can we access the subarachnoid space?

L3/4 or L4/5

125

Where does the subarachnoid space end?

Inferiorly at S2

126

Put the following steps in the circulation of CSF in order:
- Passes into left and right ventricles
- Into venous sinuses
- Secreted by choroid plexus
- Then via the cerebral aqueduct into...
- Reabsorbed from subarachnoid space via arachnoid granulation
- Into midline 3rd ventricle
- Mainly into subarachnoid space (some into central canal)
- The 4th ventricle then...

1. Secreted by choroid plexus
2. Passes into left and right ventricles
3. Into midline 3rd ventricle
4. Then via the cerebral aqueduct into...
5. The 4th ventricle then...
6. Mainly into subarachnoid space (some into central canal)
7. Reabsorbed from subarachnoid space via arachnoid granulation...
8. Into venous sinuses

127

How does raised ICP affect the eye?

Transmitted along subarachnoid space in optic nerve sheath

128

What effects does raised ICP have on the eye?

Compresses the optic nerve
Compresses central artery and vein of retine
Can lead to bulging/swollen optic discs

129

What are signs of a CN III injury?

Loss/slowness of pupillar light reflex
DIlated pupil
Ptosis
Eye turned inferolaterally:
- Unopposed action of LR and SO

130

What do the folds of dura mater create and what do they do?

Septa:
- Divide cranial cavity
-> Falx cerebri
-> Tentorium cerebelli
-> Falx cerebelli
-> Diaphragm sellae

131

How can raised ICP compress/stretch CN III?

Medial temporal lobe herniates through tentorial notch

132

In a CN IV injury, how does the eye appear and why?

SO paralysis
Inferior oblique in unopposed:
- Eye cannot move inferomedially
-> Diplopia when looking down

133

in a CN VI injury, how does the eye appear and why?

LR paralysis
Eye cannot move laterally in horizontal plane:
- Horizontal diplopia
-> Worse on looking to affected side