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Case 21 > Anatomy of the Eye and Retina > Flashcards

Anatomy of the Eye and Retina Flashcards

1
Q

what is the site of attachment for the muscles of the eye?

A

the common tendinous ring (annulus of Zinn)

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2
Q

what are the muscles of the eyelid?

A

orbicularis oculi
levator palpebrae superioris
superior tarsal muscle

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3
Q

what are the layers of the eyeball?

A

outer fibrous layer- cornea, sclera, limbus
middle vascular layer- iris, cilliary body, choroid
inner coat- retinal pigment epithelium, retina

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4
Q

where does regeneration of the cornea occur from?

A

the limbus

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5
Q

what is the function and innervation of the colliery muscle?

A

innervation- parasympathetic CNIII

function- contracts to pulls cilliary process forward causing the lens to flatten (important for near vision)

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6
Q

what is the function and innervation of the sphincter pupil and dilator pupilae?

A

sphincter pupillae- contracts pupil, parasympathetic CNIII

dilator pupillae- dilates pupil, sympathetic CNIII

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7
Q

what is the innervation and action of the rectus muscles?

A

medial- oculomotor CNIII, adduction
lateral- abducens CNVI, abduction
superior- occulomotor CNIII, elevation, adduction and intorsion (of adducted eye)
inferior- occulomotor CNIII, depression, abduction and exotorsion (of adducted eye)

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8
Q

what is the innervation and action of the oblique muscles of the eye?

A

superior- trochlear CNIV, depression, abduction and intorsion
inferior- oculomotor CNIII, elevation, adduction and extorsion

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9
Q

what is the ophthalmic artery a branch of?

A

the internal carotid

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10
Q

where does the opthalmic artery enter the orbit?

A

the optic canal

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11
Q

what does the central retinal artery supply?

A

central retinal artery- supplies inner retina

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12
Q

which nerve supplies sensation over the cornea?

A

ophthalmic branch of CNV

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13
Q

where does the lacrimal lake drain?

A

upper and lower puncta which form openings into the lacrimal canaliculi which lead to the lacrimal sac

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14
Q

where does the lacrimal sac drain?

A

the lacrimal sac drains into the nasolacrimal duct which drains into the nasal cavity via the inferior nasal meatus

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15
Q

what controls lacrimation?

A

parasympathetic nervous system

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16
Q

where is aqueous humour produced?

A

ciliary body

17
Q

where is aqueous humour found?

A

the anterior chamber between the lens and the cornea

18
Q

where does aqueous humour drain?

A

through the trabecular meshwork into the canal of schlemm

19
Q

what is open and closed angle glaucoma?

A

open- outflow of aqueous humour through the trabecular framework is reduced
closed- the iris is forced against the trabecular meshwork preventing any drainage

20
Q

what does glaucoma cause?

A

disruption of drainage of aqueous humour leads to increased intraocular pressure which causes damage to the optic nerve

21
Q

what are the layers of the retina from superficial too deep?

A 
internal limiting membrane 
nerve fibre layer 
granular layer 
inner plexiform layer 
inner nuclear layer 
outer plexiform layer 
photoreceptor layer
pigmented epithelium
22
Q

what is the function of the retinal pigmented epithelium?

A

contains a high concentration of melanin and it very dark to prevent the reflection of light back into the eye. also provides photoreceptors with vitamin A (essential for phototransduction)

23
Q

when are on centre off surround retinal ganglion cells activated/inhibited?

A

the RGC is activated when light hits the centre and inhibited when light hits the surround

24
Q

what is the function of amacrine cells?

A

they generate the inhibitory surrounds for the RGCs

25
Q

what is the function of bipolar cells?

A

transmit the signal from photoreceptors to RGCs or ACs

26
Q

what is the function of horizontal cells?

A

receive input from multiple cone photoreceptors and provide negative feedback to photoreceptors.
they generate inhibitory surrounds for bipolar cells to modulate dark adaption and increase image clarity

27
Q

what is the function of rod photoreceptors?

A

function in scotopic conditions (night/dim) and so are very sensitive

28
Q

what photopigment do rod photoreceptors have in their membranous discs?

A

rhodopsin- grey tones

29
Q

what is the function of cone photoreceptors?

A

function in photooptic conditions (bright) and have low sensitivity

30
Q

where are rods and cones concentrated?

A

rods- peripheral retina

cones- fovea/ macula

31
Q

which photopigments do cone photoreceptors have in their membranous discs?

A

one of three types of photopsin- blue green or red (provide colour vision)

32
Q

what is the resting membrane potential of photoreceptors?

A

-40mV

33
Q

what happens to the membrane potential of photoreceptors when stimulated by light?

A

they are hyperpolarised (-70mV)

34
Q

what do on centre bipolar cells do to the signals from photoreceptors?

A

on centre bipolar cells reverse the signal from photoreceptors and so are depolarised by light

35
Q

why are males more likely to have colour blindness?

A

as the genes for red and green photopsin are on the X chromosome and males only have 1 X chromosome so if there is a fault in those genes they will have colour blindness

36
Q

what is deuteranopia?

A

colour blindness caused by the absence of the gene for green photopsin

37
Q

what is protanomaly?

A

colour blindness caused by an altered gene for red photopsin

38
Q

how will a vitreous haemorrhage or a pre-retinal haemorrhage look on fundoscopy?

A

you will not be able to visualise the blood vessels as the bleed is in front of the retina

39
Q

how does an intraretinal haemorrhage appear on fundoscopy?

A

flame haemorrhage- in the nerve fibre layer

dot/blot haemorrhage- inner nuclear layer

Case 21 (4 decks)

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