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Semester 4 - Head and Neck > Session 5 - Optic shizzle > Flashcards

Session 5 - Optic shizzle Flashcards

1
Q

What makes up the roof of the orbit?

A

The frontal and sphenoid bones

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2
Q

What makes up the floor of the orbit?

A

The maxilla, zygomatic and palatine bone

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3
Q

What makes up the medial side of the orbit?

A

The ethmoid, maxilla and lacrimal bones

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4
Q

What makes up the lateral side of the orbit

A

Zygomatic and sphenoid

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5
Q

Where do fractures of the orbit occur?

A

At sutures

Often in the medial and inferior walls

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6
Q

Why are the medial and inferior walls vulnerable to fracture?

A

Walls are thin

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7
Q

What do medial wall fractures involve?

A

Ethmoidal and sphenoidal sinus

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8
Q

What do inferior wall fractures involve?

A

Maxillary sinus

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9
Q

What is a blow-out fracture?

A

A fracture that displaces the orbital wall and contents

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10
Q

What are three of the main features of orbital fractures?

A

Muscle entrapment
Diplopia
Infection

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11
Q

What is enopthalmos?

A

Depression of the eye

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12
Q

Why would enopthalmos present with a pulsating, pushed out eye?

A

Infraorbital bleeding has that effect

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13
Q

What are the two main fissures and fossae of the orbit?

A

The optic canal and the superior orbital fissure

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14
Q

What is found in the optic canal

A

The optic nerve

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15
Q

What is found in the superior orbital fissure (7)

A

Large French Teenagers Sit Numb In Anticipation Of Sweets
Lacrima nerve
Frontal nerve
Trochlear Nerve (CN IV)
Superior branch of Oculomotor Nerve (CN III)
Nasociliary Nerve
Inferior Branch of the Oculomotor Nerve (CN III)
Abducens Nerve (CN VI)
Opthalmic Veins
Sympathetic Nerves

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16
Q

How many axons come from the retinal cells?

A

1.2 million

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17
Q

What are the three main coverings of the optic nerve?

A

The Pia, Arachnoid and the dura mater

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18
Q

How can infection of the orbit effect the brain?

A

Infection can track backwards along the optic nerve, to the menininges where it can cause meningitis

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19
Q

What two structures travel with the optic nerve?

A

Central artery and vein

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20
Q

Give a potential cause of papilloedema (swelling of the optic disc) to do with veins

A

Raised ICP can lead to venous engorgement, leading to papilloedeme

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21
Q

Name the seven extraocular muscles of the eye

A

Lateral, medial, superior and inferior recti
Superior and inferior obliques
Levator palpabrae superiorus

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22
Q

What does adduction of the eye do?

A

Causes it to look medial

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23
Q

What does abduction of the eye do?

A

Caues it took look laterally

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24
Q

What is the innervation of the extraocular muscles?

A 
o	Lateral Rectus
   	Cranial Nerve 6 
   	Abducens
o	Superior Oblique
   	Cranial Nerve 4
   	Trochlear
o	All the Rest
   	Cranial Nerve 3
   	Oculomotor
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25
Q

Give three nerve lesions of the eye

A

Abducent, Trochlear and oculomotor nerve palsy

26
Q

What occurs in an abducent nerve palsy?

A

o Loss of innervation to the Lateral Rectus
 Unable to move eye laterally (abduct pupil)
 Pupil is fully adducted due to unopposed pull of medial rectus
o Caused by fractures involving orbit or cavernous sinus

27
Q

What occurs in a trochlear nerve palsy?

A

o Loss of innervation to the Superior Oblique
 Unable to look eye down when eye is adducted
o Caused by orbital fractures or stretching of the nerve during its course around the brainstem

28
Q

What occurs in an oculomotor nerve palsy?

A

o Loss of innervation to ‘All the Rest’
 Superior eyelid droops
o Ptosis
o Loss of innervation to Levator Palpebrae Superioris
o Unopposed activity of Orbicularis Oculi (Facial nerve)
 Pupil is fully dilated and non reactive
o Loss of innervation to Sphincter Pupillae
o Unopposed action of Dilator Pupillae
 Eye has moved ‘Down and Out’
 Unopposed action of Lateral Rectus and Superior Oblique
o Caused by fractures involving the cavernous sinus or aneurysms

29
Q

What is the blod supply of the eye?

A

Opthalmic artery (branch of the internal carotid artery) and central artery of the retina (Opthalmic artery)

30
Q

What occurs if the central artery of the retina is blocked?

A

End artery, total blindness will occur

31
Q

Outline the venous drainage of the eye

A

Superior and inferior opthalmic veins

Central vein of the retina

32
Q

Where do the superiro and inferior opthalmic veins leave the orbit and what do they drain into?

A

o Exit via the Superior Orbital Fissure and drain into the Cavernous Sinus

33
Q

What does the central vein of the retina drain into?

A

Cavernous sinus, directly or via opthalmic vein

34
Q

What occurs in occlusion of the centrla vein of the retina?

A

Slow, painless loss of vision.

35
Q

What is the main purposeof the eyelids?

A

Protectsa the cornea and the eyeball from injury by keeping it most with lacrimal fluid

36
Q

What lines the inner surface of the eyelid?

A

Conjunctiva

37
Q

What do the eyes do when they become dry?

A

Blink, carrying a film of fluid over the cornea.

38
Q

What are the eyelids strengthened by?

A

Tarsal plates which contain tarsal glands, which produce secretions taht lubricate the edges of the eyelids

39
Q

What is lacrima fluid?

A

Contains lysozyme, and provides nutrients and dissolved oxygen to the cornea

40
Q

Where does the lacrimal gland lie?

A

In the fossa on the superolateral part of the orbit

41
Q

What do the lacrimal ducts do?

A

Conduct lacrimal fluid from the gland to the conjuctival sac

42
Q

What is the nasolacrimal duct?

A

Conveys lacrimal fluid to the inferior nasal meatus

43
Q

How are the eye lids opened (muscles AND nerves)

A 
o	Levator Palpebrae Superioris
	Innervated by Oculomotor Nerve (CN III)
o	Assisted by Superior Tarsal Muscles
	Sympathetic innervation
	Horner’s Syndrome
44
Q

How are the eyelids closed?

A

Obicularis oculi
 Innervated by Facial Nerve (CN VII)
 Bell’s Palsy

45
Q

What happens if there is facial nerve damage, preventing the eye lids from closing?

A

The cornea becomes dry and is left unprotected from dust and other particulate material. Irritation of the eyeball results in excessive tear formation.

46
Q

What are the three main layers of the eye?

A

Outer Protective layer
Middle vascular layer
Inner retina layer

47
Q

What are the two main parts of the outer protective layer of the eye?

A

Sclera and the cornea

48
Q

What are the three main parts of the middle vascular layer of the eye?

A

Choroid
Ciliary body
Iris

49
Q

What are the tw main parts of the inner retina layer?

A

Optic part

Non visual part

50
Q

Describe the sclera

A

 Fibrous and provides attachment for the Extraocular muscles
 White, relatively avascular

51
Q

Describe the cornea

A

 Transparent, avascular
 Nourishment from lacrimal glands and vascular beds
 Sensitive – CN V1

52
Q

Describe the choroid

A

Red of eye, continues anteriorly as the ciliary body

53
Q

Describe the ciliary body

A

 Ring like thickening which is muscular as well as vascular
 Attaches and focuses the lens
 Ciliary process secretes aqueous humor into the Anterior Chamber

54
Q

Describe the iris

A

 Thin diaphragm, aperture is pupil

55
Q

What is the innervation of the iris?

A

 PSNS contracts the Sphincter Pupillae

 SNS contracts the Dilator Pupillae

56
Q

How does the iris contract?

A

Circular muscles contract

57
Q

How does the iris dilate?

A

Radial muscles cotnract

58
Q

What are the three main parts of the retina?

A

Fundus
Macula
Optic disc

59
Q

What is the fundus?

A

Posterior of the eye

60
Q

What is the macula?

A

Contains high density of rods and cones in the fovea centralis

61
Q

What is the optic disc?

A

Blind spot of retina, point of convergence of sensory fivres

62
Q

What structures does light pass through to reach the retina?

A

Cornea -> Aqueous humour -> Lens -> Vitreous humour

Semester 4 - Head and Neck (27 decks)

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