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Neuro > Vestibular Function > Flashcards

Vestibular Function Flashcards

1
Q

What is the vestibular system?

A

A sensory system essential in control of posture and balance

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2
Q

Describe the vestibular apparatus

A

3 Semi-circular canals, the utricle, the saccule

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3
Q

The ampulla, utricle and saccule contain what?

A

Hair cells

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4
Q

What makes up the otolith organs?

A

The utricle and saccule

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5
Q

What do otolith organs detect?

A

Linear accelaration and encode info about position of head in space

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6
Q

What do SCC’s detect?

A

Rotational acceleration

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7
Q

Where are sensory cells of semi-circular canals embedded?

A

The ampulla

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8
Q

What responds to movement of endolymph?

A

The cupula

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9
Q

Where are the cupula found?

A

Within the cristae which are within the ampulla

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10
Q

What lies within the cupula?

A

The cilia of hair cells which synapse directly onto CNVIII

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11
Q

What happens when the skull is rotated left or right from rest?

A

Endolymph does not move at first, due to its inertia yet the ampulla moves instantly. Inertia of endolymph produces drag which bends the cupula and its cilia in the opposite direction.

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12
Q

If the head is rotated at constant direction, what occurs?

A

Endolymph catches up and rotates at same speed, removing the shearing forces

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13
Q

What occurs if there is a sudden stop in head rotation?

A

Endolymph will continue to move due to momentum creating a sense of movement and dizziness

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14
Q

Name the two types of cilia within the ear?

A

Kinocilium and stereocilia

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15
Q

What happens if cillia is distorted towards the kinocillium?

A

Depolarisation and increased AP’s in vestibular nerve

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16
Q

What happens if cillia is distorted away from the kinocillium?

A

Hyper-polarisation and decreased discharge of APs in vestibular nerve

17
Q

Why are all cupula angled differently ?

A

The pattern of firing and inhibition received to each cupula allows the brain to determine the body’s position in time and space

18
Q

What is the sensory apparatus of the utricle and saccule ?

A

Maculae

19
Q

On which plane do macula lie in the utricle?

A

Horizontal place

20
Q

On which plane do macula lie in the saccule?

A

Vertical plane

21
Q

How is cilia arranged within the maculae?

A

One kinocillium and a series of sternocilium which protrude into the otolith membrane

22
Q

What is embedded within the otolith membrane?

A

Otoliths, CaCO3 crystals

23
Q

Where do projections from vestibular nuclei on one side project?

A

Ipsilaterally, bilatterally and contralaterally to descending motor pathways

24
Q

Where do vestibular nuclei receive input from?

A

Proprioceptors signalling limb and body position and from neck/eye muscles

25
Q

Kinaethesia is achieved by what?

A

Vestibular nuclei projecting via the thalamus to the cerebral cortex which results in perception of movement and body position

26
Q

What are tonic labyrinthe reflexes?

A

A primitive reflex which keeps the axis of the head in a constant relationship with the rest of the body

27
Q

What are dynamic righting reflexes?

A

A reflex which corrects the orientation of the body when it is taken out of the normal upright position. Stops you falling when you trip

28
Q

What is the static reflex?

A

When you tilt your head, eyes extort/intort to compensate so the image will stay the right way up

29
Q

Describe dynamic vestibular nystagmus

A

A series of saccadic eye movements that rotate eye against direction of rotation of head and body so direction is gaze is preserved

30
Q

When are you most likely to get symptoms of motion sickness?

A

When visual and vestibular inputs to the cerebellum are in conflict

31
Q

What happens when there is acute interference with normal vestibular function as a result of infection?

A

Vertigo

32
Q

What is menieres disease?

A

Vertigo, nausea, nystagmus and tinnitus due to over production of endolymph

Neuro (16 decks)

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