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Head and Neck > 8) Anatomy of Orbit and Eyeball > Flashcards

8) Anatomy of Orbit and Eyeball Flashcards

1
Q

What is contained in the orbit?

A

Eyeball, its muscles, nerves, vessels and lacrimal apparatus

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2
Q

What bones form the superior orbit?

A

Frontal and sphenoid

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3
Q

What bones form the lateral orbit?

A

Zygomatic and sphenoid

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4
Q

What bones form the medial orbit?

A

Ethmoid, maxillary, lacrimal and sphenoid

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5
Q

What bones form the inferior orbit?

A

Maxillary and zygomatic

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6
Q

What are the entrances to the orbit and through which bone?

A

Optic canal, superior orbital fissure and inferior orbital fissure
Sphenoid bone

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7
Q

What are the vulnerable points of the orbit?

A

Inferior and medial walls are thin

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8
Q

What are the 3 layers of the eyeball?

A

Outer fibrous
Middle vascular
Inner

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9
Q

What does the outer fibrous layer consist of?

A

Sclera and cornea

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10
Q

What does the middle vascular layer consist of?

A

Choroid, ciliary body and iris

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11
Q

What forms the inner layer of the eyeball?

A

Retina

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12
Q

What features can be seen in fundoscopy?

A

Optic disc - where optic nerve enters eye

Vessels, macula with fovea at centre

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13
Q

How can you tell which eye is being examined by the fundus?

A

Optic disc is on nasal side

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14
Q

What are the consequences of retinal detachment?

A

If left too long, cells of retina will die leading to partial blindness

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15
Q

How can meningitis affect the eye and why?

A

Optic nerve is surrounded by meninges so inflammation can cause photophobia - discomfort or pain of light exposure

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16
Q

What are the three chambers of the eye?

A

Anterior: cornea to iris
Posterior: iris to lens
Vitreous: filled with vitreous humour

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17
Q

How does the aqueous humour drain?

A

Irido-corneal angle into canal of Schlemm via trabecular meshwork then into venous circulation

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18
Q

What is glaucoma?

A

Obstruction in drainage of aqueous humour so intra-ocular pressure increases

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19
Q

What are the consequences of untreated glaucoma?

A

Damage to optic nerve = vision impairment and blindness

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20
Q

What is the cause of open angle glaucoma?

A

Blockage in trabecular meshwork, causing rise in intra-ocular pressure, cupping of optic disc and/or visual field loss

21
Q

What is the treatment for open angle glaucoma?

A

Reduction in production of aq. humour or surgery

22
Q

What is the cause of closed angle glaucoma?

A

Irido-corneal angle narrowed as access to trabecular meshwork is blocked off. Rapid rise in intra-ocular pressure

23
Q

How does closed angle glaucoma present?

A

Painful red eye, blurred vision, oval shaped pupil, hard eye

24
Q

What is the treatment for closed angle glaucoma?

A

Muscarinic eye drops, analgesia and drugs to reduce intra-ocular pressure

25
Q

Describe the iris:

A

Coloured and have sphincter and dilator pupillae muscles

26
Q

What structure are involved in changing lens shape?

A

Ciliary muscle fibres, suspensory ligaments and autonomic nerves

27
Q

What causes cataracts?

A

Degradation of proteins in lens

28
Q

What is the accommodation reflex?

A

Automatic contraction of pupil and convergence of eyes when suddenly focusing on a near object after a distant object

29
Q

What is presbyopia?

A

Impaired ability to accommodate

30
Q

What is the mechanism of the accommodation reflex?

A

Contraction of ciliary muscles causes loosening of suspensory ligament and lens becomes rounder

31
Q

What are the functions of the eyelids and lacrimal glands?

A

Preventing injury, foreign bodies, excessive light and dryness

32
Q

What gives eyelids their shape?

A

Tarsal plates (dense bands of CT)

33
Q

What is the difference between a Meibomian cyst and a stye?

A

Cyst - tarsal gland inflamm

Stye - pus in ciliary glands

34
Q

What muscles cause opening of eyelid?

A 
Levator palpabrae superioris (CN III)
Superior tarsal (sympathetic) (minor)
35
Q

How would an oculomotor lesion and Horner’s syndrome differ in presentation (eyelid)?

A

Complete ptosis in CN III lesion

Partial in Horner’s

36
Q

Describe the drainage of tears:

A

Lacrimal lake at medial angle of eye, then in lacrimal sac via lacrimal canal. Into nasal cavity by nasolacrimal duct

37
Q

What is the conjunctiva and its clinical relevance?

A

Film on top of cornea

Inflamed in conjunctivitis causing redness

38
Q

Describe the arterial supply to the eye:

A

ICA -> ophthalmic artery -> central retina artery

39
Q

Describe the venous drainage of the eye:

A

Central retinal vein -> superior ophthalmic vein -> cavernous sinus

40
Q

What is the innervation of the extra-ocular muscles?

A

LR6 SO4 R3

41
Q

Where do the recti muscles originate?

A

Common tendinous ring around optic canal

42
Q

Where do the oblique muscles arise?

A

Bony walls of orbit

43
Q

What does superior oblique travel through?

A

Trochlea (ligament sling)

44
Q

What is the movement of superior oblique?

A

Down and in

45
Q

What is the movement of inferior oblique?

A

Up and in

46
Q

What is the movement of superior rectus?

A

Up and out

47
Q

How would you test the eye muscles in isolation?

A

Line up gaze with line of attachment of muscle e.g. SR - look out then ask to move eye up

48
Q

How does a blow out fracture of the orbit present?

A

Blood in maxillary sinus
Inferior rectus moves down so eye can’t move upwards (tethered)
Loss of sensation under eye, damage to infra-orbital nerve

Head and Neck (17 decks)

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