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HNN > week 5 > Flashcards

week 5 Flashcards

1
Q

what is the presenting symptom in 70% of parkinsons disease?

A

Tremor
always starts in the fingers and hand and is unilateral initially , then spreading to leg on same side and then opposite arm. the tremor is present at rest and reduces or stops when hand is in motion.

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2
Q

histology of macula , order of cells from innermost to outer

A 
ganglion cells
bipolar cells
photoreceptors 
retinal pigment epithelium 
choroid
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3
Q

histology characteristics for macula

A

cone photoreceptors only
reading facial recognition and visual activity
no blood vessels - dependent on choroid for oxygen and metabolic support

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4
Q

age related diagnosis for macula degeneration

A

exudative - new blood vessels growing under retina from choroid - rapid metamorphopsia

atrophic - atrophy of outer retina - slow blurring

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5
Q

what is tested at a macular clinic

A

visual acuity
metamorphopsia
dilated fundus exam and other investigations

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6
Q

visual acuity

A

Recorded as the distance chart is read /

distance at which it should be read

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7
Q

what other investigations are there on the macula

A

fundus fluorescein Angiogram .
inject fluorescein intravenously
fluorescein bound to albumin - remains within normal capillaries beacuse of blood-retinal barrier .
use blue flash and yellow filter to see details of retinal circulation

Optical coherence tomography

  • low powered laser interferometry
  • generates detailed cross -sectional image of retina
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8
Q

what is the fovea

A

In the eye, a tiny pit located in the macula of Fovea centralis is a small depression in the centre of the macula
lutea that contains only cones
ƒ Layers of bipolar and ganglion cells do not cover the cones here
and are displaced to the periphery of the fovea centralis
ƒ Fovea centralis Æ area of highest visual acuity

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9
Q

how does age-related macula densa cause blindness

A

blood vessels and scar tissue grow under retina

leaking vessels cause retinal oedema

block transport of oxygen and nutrients from choroid

eventual scarring causes destrution of photoreceptos

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10
Q

what are photorecpetors

A

specialised cells that begin the process by which light rays are converted to nerve impulses

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11
Q

what are the two types of photoreceptor

A

rods - allow vision in dim light , do not provide colour vision , black and white and all shades of grey

cones - stimulated by brighter lights , produce colour vision, three types of cones blue, red and green , colour vision results from the stimulation of various combinations of these types of cones

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12
Q

why is the optic disc known as he blind spot

A

cause it has no rods or cones

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13
Q

characteristics of the cornea

A

ƒ Transparent coat that covers the iris
ƒ Curved -> helps focus light on the retina
ƒ Outer surface consists of nonkeratinsed stratified squamous
epithelium
ƒ Middle coat -> collagen fibres and fibroblasts
ƒ Inner coat -> simple squamous epithelium
ƒ Central part of cornea receives oxygen from the outside air ->
contacts must be permeable to permit oxygen through them

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14
Q

sclera characteristics

A

White of the eye
ƒ Layer of dense connective tissue
ƒ Composed mainly of collagen fibres and fibroblasts
ƒ Covers the entire eyeball except for the cornea
ƒ Gives shape to the eyeball
ƒ Protects the inner parts
ƒ Serves as a site for attachment for extrinsic eye muscles

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15
Q

what is the junction of the sclera and cornea

A

scleral venous sinus- aqueous humour drains into the sinus

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16
Q

what are the layers of the eyeball?

A

The eyeball has three concentric coverings : (1) an external, fibrous tunic comprising the cornea and sclera; (2) a middle, vascular tunic comprising the iris, ciliary body, and choroid; (uvea) and (3) an internal, nervous tunic, or retina

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17
Q

what is the vascular tunic composed of ?

A

choroid , ciliary body and iris

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18
Q

what is the choroid

A

Highly vascularised
ƒ Posterior portion of the vascular tunic
ƒ Lines most of the internal surface of the sclera
ƒ Numerous blood vessels supply the posterior surface of theretina
ƒ Also contains melanocytes that produce melanin which causes
this layer to appear dark brown in colour

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19
Q

what does melanin do to light?

A

ƒ Melanin absorbs stray light rays , so prevents reflection and
scattering of light within the eyeball
ƒ As a result, image cast on the retina by the cornea remains sharp
and clear

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20
Q

characteristics of ciliary body?

A

In the anterior portion of the vascular tunic, the choroid
becomes the ciliary body
ƒ Extends from the ora serrata, the jagged anterior margin of the
retina, to a point just posterior to the junction of the sclera and
cornea
ƒ Appears dark in colour because of melanin
ƒ Consists of ciliary processes and ciliary muscle

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21
Q

what are the suspensory ligaments

A

they attach to the tips of the ciliary processes and these ligaments hold the lens posterior to the iris.

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22
Q

what does contraction of the ciliary muscles do?

A

tightens the suspensory ligaments , causes the lens to flatten , thus accommodating for near distance objects.

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23
Q

what does the ciliary blood capillaries secrete?

A

aqueous humour

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24
Q

characteristics of the iris?

A

suspended between cornea and lens.
attached at outer margin to ciliary processes .
contains blood vessels , melanocytes and 2 layers of smooth muscle called pupillary muscles.

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25
Q

what causes constriction of eye pupil

A

bright light stimulates eye.
parasympathetic fibres of CN III stimulate the circular muscles or constrictor pupillae muscles of the iris to contract.

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26
Q

what is the dilation of the eye pupil caused by?

A

dim light stimulates eye.

sympathrtic neurons stimulate the radial muscles of the dilator pupillae of the iris to contract.

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27
Q

retina characteristics

A

lines the posterior 3/4 of the eyeball. surface of the retina is the only place in the body where the blood vessels can be viewed directly and examined for pathologies

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28
Q

what is the optic disc

A

where the optic nerve exits the eyeball

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29
Q

what is bundled together with the optic nerve

A

central retinal artery , a branch of the opthalmic artery and the central retinal vein.

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30
Q

retina consists of what layers

A

pigmented layer and neural layer

31
Q

what does the retinal pigmented epithelium do?

A

absorbs light that passes through the neural part , preventing light from bouncing back through the neural part and producing visual echos.
it also actively pushes water out , this flow of water keeps the retina attached to the choroid

32
Q

what is the pterion

A

is the region where the frontal, parietal, temporal, and sphenoid bones join together. It is located on the side of the skull, just behind the temple

33
Q

what is a muller cell

A

supporting glial cell

34
Q

what is the distribution of rods and cones in the retina

A

rods are found dispersed widely in the periphery of the retina. cones are abundant in the macula (macula contains no rods) the highest concentration of cones is seen in the fovea.

35
Q

horizontal and amacrine cells do what?

A

can facilitate or inhibit communication between photoreceptors and ganglion cells , thereby altering the sensitivity of the retina , these cells play an important role in the eyes adjustment to dim or brightly lit environments

36
Q

lens characteristics

A

made up of proteins called crystallins , arranged like layers of an onion which makes up refractive media of the lens.
enclosed by a clear connective tissue capsule , held in position by encirculing zonular fibres which attach to the ciliary processes.
helps focus image on retina.
divides the interior of the eyeball into the anterior chamber and posterior chamber

37
Q

what are the boundaries of the anterior chamber

A

lies between cornea and iris.

filled with aqueous humour

38
Q

what are the boundaries of the posterior chamber

A

lies between the iris and in from of the zonular fibres and the lens . filled with aqueous humour

39
Q

what is aqueous humour

A

transparent watery fluid that nourishes lens and cornea . it continually filters out of the blood capillaries in the processes of the ciliary body and enters post chamber. from the anterior chamber the humour drains into the scleral venous sinus and into blood.

40
Q

what is the vitreous chamber

A

lies between retina and lens .
within it is the jelly like substance which holds the retina against the choroid . consists mostly of water , collagen fibres and hyaluronic acid . contains phagocytic cells to remove debris

41
Q

what is the hyaloid canal

A

a narrow channel that is not clearly visible in adults , and runs through the vitreous body from the optic disc to the posterior aspect of lens

42
Q

what is pressure in the eye called

A

intraocular pressure. 16mmHg

43
Q

what is the visual pathway

A

photoreceptors in retina

  • > optic nerve
  • > optic chiasm
  • > optic tract
  • > lateral genticulate nucleus
  • > projection fibres (optic radiation)
  • > visual cortex of cerebral hemispheres
44
Q

WHAT is the relation of the cerebral blood vessels and the meninges

A

the vessels lie in the subarachnoid space - between pia and arachnoid

45
Q

what symptoms are likely to result from an infarction of the posterior limb of internal capsule

A

contralateral hemiparesis

46
Q

what do the three layers of meninges form in the optic nerve

A

the outer sheath
the intermediate sheath
the inner sheath

47
Q

what is the visible distortion of the optic disc?

A

papilloedema / optic neuritits

48
Q

what is seen in a opthamoscope images in papilloedema

A

moderate - there is a crescent of oedema surrounding the optic disc
severe- a halo of oedema surrounds the optic disc

49
Q

what can papilloedma result from

A

it is a clinical sign of increased intracranial pressure - could result from tumours , malignant hypertension, head injury, haemorrhage

50
Q

partial or complete loss of vision in ipsilateral eye could be caused by?

A

acute optic neuritis - MS
indirect traumatic optic neuropathy
optic atrophy

51
Q

loss of vision in temporal visual fields of both eyes causes>?

A

tumours- pituitary adenoma , meningioma
aneurysms
- term is bitemporal hemianopia

52
Q

lesions of optic tract exhibits what?

A

loss of vision in same visual field of both eyes - left or right.
termed homonymous hemianopia
- caused by tumours , trauma, aneurysm of post cerebral artery

53
Q

what lesions in the visual pathway can lead to homonymous hemianopia

A

optic radiation, visual cortex and optic tract

54
Q

do all optic nerve fibres project to the lateral geniculate nucleus ?

A

no, some fibres project to the superior colliculus or to the pretectal area of the midbrain

55
Q

what is the superior colliculus responsible for in the visual pathway

A

eye movements

56
Q

what function is the pretectal area responsible for in the visual pathway?

A

pupillary light reflex

57
Q

what is goldmann perimetry

A
  • Goldmann perimetry tests assess the extent of the visual field
  • A test light is used as the stimulus (kinetic or static)
  • Visual field can be mapped according to detection of the light
58
Q

what is pupillary light reflex

A

pupil constriction in response to light

59
Q

what is the accommodation reflex ?

A

pupil constriction and convergence of the eyes when looking from one distant object to a close one

60
Q

what can the swinging flashlight test detect

A

Relative afferent pupil defect

61
Q

exam of the pupils

A
  1. Inspect pupils, looking for any asymmetry or
    irregularity
    - a small difference in size (1-2 mm or less) can
    be normal
  2. Check the direct and consensual reactions to light
  3. Swinging Light Test for a RAPD
  4. Accommodation-Convergence Reflex
62
Q

accommodation convergence reflex

A

stimulus is a out of focus image

  • pupil constriction - constrictor pupillae
  • lens accommodation - ciliary muscles
  • convergence of eyes - contraction both medial rectus muscles

pathway is more comples as requires visual processing
afferent pathway - optic nerve
efferent - oculomotor

63
Q

what response may be elicited when a light is shone in one eye

A

Shining a light into the eye causes the consensual constriction of the pupil in
both eyes. This is called the light reflex. The nervous pathway involves
collateral fibres from the optic tract forming synapses within the superior
colliculus / pretectal nucleus and the accessory oculomotor (Edinger Westphal)
nucleus in the tectum of the midbrain.
The efferent, consensual parasympathetic fibres of the reflex arc travel in
the oculomotor nerve to synapse in the ciliary ganglion. Postganglionic
fibres leave the ciliary ganglion and pass to the sphincter muscle of the
pupil. Stimulation of these nerve fibres results in consensual constriction of
the pupil in both eyes.

64
Q

damage to pretectal nucleus within superior collicus would mean what for visual pathwyays ?

A

lack of pupillary light response when light shone at eye

65
Q

damage to the oculomotor would mean what for the visual pathways

A

failure of tracking of a moving object , dilated fixed pupil

66
Q

what is a landmark for the primary visual cortex

A

the calcarine sulcus. the primary visual cortex is within the superior and inferior calcarine gyri

67
Q

what is the blood supply to the primary visual cortex

A

the posterior cerebral artery

68
Q

what is the respiratory epithelium

A

PSEUDOSTRATIFIED ciliated columnar epithelium with goblet cells

69
Q

what cavities are in the nasal passages

A

cavity of sphenoidal air sinus
cavity of ethmoidal air sinuses

cavity of frontal air sinus

70
Q

what CNs go through the cavernous sinus

A

CN III
CN IV
CN VI

71
Q

what is a dendrite ?

A

afferent neuronal cell process

72
Q

what is the functional contact point between two neurons called?

A

a synapse

73
Q

gray type 2 synapses have Flattened synaptic vesicles , what do gray type 1 have

A

spherical synaptic vesicles

HNN (13 decks)

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