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Head and neck > Session 8- Functional Anatomy of the orbit, eye and ocular muscles > Flashcards

Session 8- Functional Anatomy of the orbit, eye and ocular muscles Flashcards

1
Q

what is the orbit

A

a bony pyramid housing the eyeball, its muscles, nerves vessels and most of the lacrimal apparatus

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2
Q

which are the weakest walls of the orbit

A

inferior and medial making them most vulnerable to fracture

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3
Q

what does fracture of the orbit lead to

A

a sudden increase in introrbital pressure and is often the floor that fractures

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4
Q

what makes the medial wall stronger than the inferior wall

A

although it is thinner than the inferior wall the presence of the walled air cells act as buttresses and convey an added strengh to the medial wall

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5
Q

what becomes infected in acute sinusitis

A

walled ethmoidal air cells

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6
Q

what travels through the inferior orbital fissure

A

infraorbital nerve- branch of Vb

inferior opthalmic vein

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7
Q

what series of holes are at the apex of the orbit

A

optic canal
superior orbital fissure
inferior orbital fissure

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8
Q

what is the transparant continuation of the sclera

A

cornea

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9
Q

what does the sclera provide in terms of attachemnt

A

extra-ocular muscles

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10
Q

what thin transparent layer of the cells cover the sclera

A

conjunctivae

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11
Q

treatment of conjuctivitis

A

reassurance
hygeine advice
short course of chloramphenicol eye drops

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12
Q

what is a cause of conjuctivitis in the neonatal period

A

an infective organism like chlamydia picked up from the mother’s vaginal mucosa during birth

treated with erythromycin

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13
Q

what causes subconjuctival haemorrhage

A

when one of the small conjuctival blood vessels rupture and the blood escapes under the transpareny conjunctival layer

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14
Q

what does the choroid continue as anteriorly

A

cilary body and iris

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15
Q

what does the cilary body consist of

A

cilary process and muscle

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16
Q

function of cilary body

A

connects choroid and iris

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17
Q

what alerts you with a red eye

A

if it is painful as this indicates a serious underlying cause
uveitis

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18
Q

what is uveitis

A

inflammation of the choroid layer

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19
Q

what is the uvea

A

collective term for choroid, cilary process and iris

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20
Q

what does the outer layer o the eyeball consist of

A

sclera

cornea

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21
Q

what does the middle layer of the eueball consist of

A

choroid
cilary body
iris

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22
Q

what does the innerlayer of the retina consist of

A

neurosensory cell layer

pigmented epithelial cell layer

23
Q

what layers are within the retina

A

neurosensory cell layer

pigmented epithelial cell layer

24
Q

where does the pigmented epithelial layer lie

A

betweem the choroid and neurosensory layer of the retina

25
Q

what is the role of the melanin in the pigmented epithelial cells

A

helps absorb scatterd light that has passed into the eye

26
Q

function of neurosensory layer

A

area of the retina that senses light and where photoreceptors are found

27
Q

what are the cones responsible for

A

high visual acuity and color vision

28
Q

where are the cones concentrated

A

macula

29
Q

how does the macula appear on fundoscopy

A

darker

lying lateral to optic disc

30
Q

what is the centre of the macula called

A

fovea

31
Q

what is present in the fovea

A

small area where the only photoreceptors are cones

32
Q

what causes colour blindness

A

absence of dysfunction of one of the red green or blue cone leads

33
Q

what is the function of rods

A

responsible for vision in low intensity ligjt and do not discern colours

34
Q

where are rods abundant

A

peripheral parts

35
Q

what is the optic disc

A

accumulation of retinal axons making it devoid of photoreceptors making it the blind spot

36
Q

what are the three chambers of the eyeball

A

anterior, posterior and virteous chamber most posteriorly

37
Q

what is the virteous chamber filled with

A

transparent, jelly like virteous humour

38
Q

what are the anterior and posterior chambers filled with

A

transpaarent liquid called aqeuos humour

39
Q

where is the anterior chamber

A

space between the cornea and iris

40
Q

where is the posterior chamber

A

space between the iris and lens where the cillary body and processes are found

41
Q

what is aqueous humour important for

A

supporting the shape of the eyeball by the pressure it exerys

provides nourishment to the lens and cornea

42
Q

where does aqueous humour drain

A

irido-corneal angle into the canal of schlemm via a trabecular meshwork and subsequently back into venous circulation

43
Q

what happens to the deainage of aqueous humor as we age

A

it can become obstructed which leads to a ris ein intra-ocular pressre leading to glaucoma

44
Q

what is glaucoma

A

irreversible damahe and death of optic nerve

45
Q

what is the most common type of glaucoma

A

open-angle glaucoma

46
Q

what causes open angle glaucoma

A

blockage within the trabecular meshwork

47
Q

why is open angle glaucoma hard to pick up

A

it develops painlessly and insidiously over time

48
Q

what is closed angle glaucoma

A

when the irido-corneal angle is narrowed by the peripheral edge of the iris

access to trabecular meshwork is blocked off

rise in intraocular presuure

49
Q

how does closed angle glaucoma present

A 
sudden onset of a painful red eye
blurred vision
fixed sluggish semi-dilated irregular oval shaped pupil
nausea
vomiting 
eye feels hard to palpate
50
Q

what muscles form the iris

A

spinchter and dilator pupillae which are under the control of the ANS

51
Q

what supplies nutrients to the lens

A

aqueous humour

52
Q

what is cataracts

A

degredation of the proteins in the lens causes it to become clouded and less transparent

53
Q

how is the shape of the lens altered

A

contraction of the ciliary muscle under the influence of the PNS alters the tension in the suspensory ligaments

54
Q

From what artery does the arteries in the optic disc arise from

A

Central retina,

Head and neck (19 decks)

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