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Anatomy > Neuro: eye > Flashcards

Neuro: eye Flashcards

1
Q

what produces the watery aqueous humour and where is it absorbed

A

ciliary body (produced)

reabsorbed = sinus venous (canal of schlemm)

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2
Q

how do you increase refractive power of the lens

A

Relaxation of suspensory ligaments

Lens becomes thicker

Increase in refractive power

Lens bends light more effectively - reducing focal length of the lens

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3
Q

normal intraocular pressure

A

12-22mmHg

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4
Q

What feature, seen on fundoscopy, would suggest raised intraocular pressure?

A

Papilledema - optic disc swelling

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5
Q

what is the limbus

A

Sclerocorneal junction

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6
Q

Why might a loss of sympathetic innervation cause mild drooping (ptosis) of the eyelid?

A

Inactivates superior tarsal muscle (muller’s muscle) which normally lifts the eyelids
(under the Levator palpebral superioris)

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7
Q

Why might more of the sclera be visible in anxiety states / hyperthryoidism?

A

usually only Small portion of sclera is often visible below the iris but not above

but then More of the upper sclera. during anxiety/hyperthyroidism

excaberation of sympathetic nervous system–> increased contraction of muller’s muscle(superior tarsal muscle) via sympathetic fibres = widen eyes

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8
Q

What is an orbital “blowout” fracture?

A

Blunt trauma to eye eg. Punch to eye

Inferior medial walls giveway

this can raise intraorbital pressure

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9
Q

3 layers/tunics of eye

A

Fibrous - sclera/cornea

Vascular

neural - retina/fovea

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10
Q

components of the vascular tunic

and what are they known as

A

Choroid
Ciliary body
Iris

these are known as the “uveal tract”

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11
Q

what corresponds to the physiological blind spot (On the retina)

A

optic disc

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12
Q

what branch is the central retinal artery and where does the vein drain into

A

CRA branch of ophthalmic artery

CRV drains into superior opthalmic vein

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13
Q

clinical term for inflammation within the vascular tunic of the eye

A

uveitis

uvea = iris/choroid/ciliary body of vascular tunic

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14
Q

what fibres make up the suspensory ligament

A

zonule

the tension in the fibres flattens the anterior surface of the lens

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15
Q

what structures provides the refractive power of the eye

A

curvature of transparent cornea = 2/3rds of the refractive power (~40diopters)

lens curvature = 1/3rd (20 diopters)

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16
Q

what fossa is the lens found in

A

hyaloid fossa

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17
Q

posterior/anterior chambers and segments

A

the chambers are within the anterior segment of the eye

So within anterior segment:
AC is the aqueous humor-filled space inside the eye between the iris and the cornea’s innermost surface, the endothelium

PC space behind the peripheral part of the iris, and in front of the suspensory ligament of the lens

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18
Q

myopia

A

short sightedness

eye grows too long (front to back) >24mm

long distance objects are blurred because light is focused in front of the retina

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19
Q

cranial nerves supplying the eye

+ what muscles do they supply + where do they emerge from

A

III: oculomotor between cerebral peduncles

  • Medial, inferior and superior rectus
  • Inferior oblique
  • Levator palpebrae superioris
  • Sphincter pupillae (parasympathetic)
  • Ciliaris muscle (parasympathetic)

IV: trochlear below inferior colliculi (exits brainstem posteriorly)
-superior oblique

VI: abducens from pontomedullary junction
- lateral rectus

20
Q

What is transtentorial herniation?

and what might be a warning sign

A

Medial temporal lobe (uncus/parahippocampal gyrus) –> tectorial hiatus (—>foramen magnum) —> compression of oculomotor

may occur due to hemispheric space occupying lesion eg. tumor/haematoma (swelling/oedema)

sudden dilation of one pupil = oculomotor on one side is damaged

21
Q

origin of the 6 extra ocular muscles

A

4 rectuses = common tendinous ring

inferior oblique = ring orbital surface of maxilla

superior oblique = from common tendinous–> trochlea(attached to sphenoid)–> posterior superior of eye

22
Q

2 muscles that intort the eye

A

superior oblique and medial rectus

23
Q

Weakness of which extraocular muscle might affect reading or walking downstairs?

A

superior oblique

24
Q

clinical features of complete 3rd nerve palsy

A

extropia - eyes outward
(because LR still working)

hypotonia - downward
(because SO still working)

ptosis - drooping eyelids
(no levator palpebrae superioris muscle)

mydriasis - pupil dilation (no ciliaris)

25
Q

part between tonsils in cerebellum

A

uvula

26
Q

What is the vesibulo-ocular reflex and which part of the cerebllum contributes to it?

A

Moving head to side/body is moving, eyes remain straight looking

vestibularcerebellum (Follicular nodular lobe)

27
Q

Which features of being drunk are due to impairment of cerebellar function?

A

Slurred speech
Gait
Dysmetria - lack of coordination of movement (type of ataxia)

28
Q

cerebellar peduncles

medial
inferior and superior

A

medial (largest)
-afferent neurones

inferior

  • afferent from medulla oblongata
  • gives spinal proprioceptive information for gait and balance

superior

  • projects upwards to mibrain
  • main efferent pathway from cerebellum(dentate nucleus)—> thalamus
29
Q

palpebral fissue

A

vertical space between medial and lateral canthi

30
Q

tough sclera of eye

A

fibrous layer of globe and continuous with dura mater surrounding optic nerve

31
Q

difference between the visual and anatomical axis

A

around 22.5

32
Q

During clinical testing of the superior and inferior rectus muscles, the eye would ideally be abducted by how many degrees, so that the visual and anatomical axes coincide?

A

Due to the direction of the medial and lateral walls there is a difference between the visual and anatomical axis. When the eyes are abducted by 22.5o, then the superior and inferior rectus muscles act as pure elevators and depressors of the eye. Contraction of the superior and inferior rectus muscles from the primary position would also cause rotation of the eye globe which is not suitable for differentiating between muscles in a clinical setting.

33
Q

what does outer/fibrous layer consist of (eye)

A

sclera
cornea
limbus

34
Q

what is the area called where the optic nerve arises from the sclera

A

lamina cribrosa

35
Q

what does the neural layer of eye consist of

A

macula lutea
retina
fovea centralis

36
Q

where does the neural retina end

A

at ora serata

37
Q

hyaloid canal

A

transparent canal running through vitreous body from optic nerve disc to lens

38
Q

equivalent of gyri and sulci in cerebellum

A

folia = gyri

fissures = sulci

39
Q

In advanced raised intracranial pressure the tonsils may herniate through the foramen magnum and cause death by compressing which part of the brain stem?

A

The medulla, which contains vital (cardiorespiratory) centres.

40
Q

dysmetria

A

problem in the ability in estimating distances during movements and placing limbs accurately when reaching for targets

hyper metria = overshooting/can’t reach

hypo metria = attempting to reach for something and end up knocking it over

41
Q

3 functional divisions of cerebellum

A

vestibulocerebellum
- flocculonodular lobe = balance/equilbrium

Spinocerebellum
- vermis + anterior lobe = gait/posture/tone

neocerebellum/cerebrocerebellum
- posterior lobe + tonsils = coordination/smooth accurate movements / speech articulation

42
Q

Q Which might Goliath not have seen David and his slingshot? (Clue: growth hormone)

A

As goliath may have had a growth-hormone-secreting (somatotroph) pituitary adenoma (acromegaly) which would explain his gigantism and may have lead to bitemporal hemianopia (tunnel vision)

43
Q

Why is the superior oblique sometimes called the tramp’s muscle?

A

because of the way it deflects the pupil: down and out.

44
Q

Use the method shown in the lecture to explain the action of superior oblique when the eye is in the primary (anatomical) position?

then use the same method to explain why the superior oblique acts as a pure depressor of the adducted eye [as in clinical testing]?

A

intortion

As it no longer rotates the eye, and is straightened out – allowing it to simply depress the eye

45
Q

Diplopia (double vision) on far lateral gaze is most likely to be caused by weakness of which muscle?

A

Lateral rectus (supplied by CN VI).

46
Q

what nerve is the constrictor papillae innervated by

A

PARASYMPATHETIC innervation by oculomotor

that arise from edinger-westphal nucleus

Anatomy (12 decks)

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