Vestibular Systems (Incomplete!!)

Question 1

Where is the inner ear?

Answer 1

inside the temporal bone

-> well protected in the petrous part of the temporal bone

Question 2

Otholit

Answer 2

• carbonate cristals

- on

Question 3

What are the 4 vestibular nuclei?

Answer 3

superior
lateral
medial
inferior

=> receive vestibular, visual etc. inputs and generate reflexes (rewatch this part)

Question 4

What are the inputs and outputs of the vestibular system?

Answer 4

Input:

• visual
• vestibular (gravity and rotation)
• Pressure (e.g. stepping on something)

Output:

• ocular reflex
• postural control
• nausea

Question 5

What are semicircular canals filled with?

Answer 5

Endolymph

Question 6

What are the names of the semicircular canals?

Answer 6

• superior (or anterior)
• posterior
• lateral -> this is the one that lies horizontally

=> they are all in 90 degree angles to each other

Question 7

What are the otolithic organs?

Answer 7

• utricle
• saccule

=> help to detect linear acceleration and head positioning. Within these structures are crystals that are attached to hair cells in a viscous substance. In movement the crystals move in the substance because they are heavier than it is and they pull on the hair cells. This triggers an AP that carries information to the brain

Question 8

What do the semicircular canals detect and how?

Answer 8

• when we move, the endolymph in the canals moves as well

Question 9

Hair cell types

Answer 9

Type I:

• More in number
• Direct afferent, indirect efferent
• round shape

Type II:

• Direct afferents and efferents
• more efferents, less afferents
• shaped more like cones

=> they are all together, the distribution is not as special as in the cochlea.

Question 10

What is dizziness?

Answer 10

An illusion of self- and/or environmental motion

Question 11

What is vertigo?

Answer 11

• Illusory selfmotion which is spinning in nature

- a subset of dizziness

Question 12

What is oscillopsia?

Answer 12

Visual world motion

Question 13

How does oscillposia differ from vertigo?

Answer 13

Vertigo is present even with one’s eyes shut

Question 14

What are causes of acute vertigo and their frequencies?

Answer 14

• Very common – BPPV
• Common – migraine, postural hypotension Occasional–vestibular neuritis,cerebellar stroke or brainstem stroke o - Rare – Meniere’s disease
• Very rare – vestibular paroxysmia, vestibular epilepsy

Question 15

What are hardcore examinations in acute vertigo?

Answer 15

• Eyes – nystagmus, head impulse test, Hallpike test
  Ears – otoscopy (also hearing test?)
• Legs–gait ataxia

Question 16

What are red flags for acute vertigo?

Answer 16

Headache,gait ataxia, hyperacute onset,hearing loss

-> Stroke?

Question 17

Which cranial nerve is responsible for balance?

Answer 17

vestibulocochlear - splits in the area of the inner ear Ito.a vestibular nerve and cochlear nerve.

Question 18

What are the vestibular organs?

Answer 18

There are 5 in each ear:

• 2 otolith organs: utricle and saccule
• 3 semicircular canals: anterior/superior, posterior and lateral SCC

Question 19

Which vestibular organ is directly connected to the cochlea?

Answer 19

Sacculus

Question 20

How are the vestibular organs connected?

Answer 20

• SCCs are connected to the utricle
• the utricle is connected to the sacculus
• saccule is connected to the cochlea

=> everything is connected in the inner ear

Question 21

Is the fluid in the hearing and vestibular system the same?

Answer 21

yes because everything is connected.

Question 22

What are the fluids in the inner ear?

Answer 22

• endolymph - inside the structure

- perilymph - outside the structures, between organs and the bone.

Question 23

What is the structure of a semi circular canal?

Answer 23

• each canal has an ampulla -> each canal has to attachments to the utricle, one is the extreme with the ampulla, the other is without.

Question 24

How can you differentiate the semi circular canals?

Answer 24

• orientation
• there are 2 canals that attach together on the non-ampulla side: anterior/superior and posterior/inferior
• the other canal (lateral/horizontal) attaches on its own on its non-ampulla end.

Question 25

How are the semicircular canals oriented?

Answer 25

• anterior: they are 45 degrees to the front (imagine a line going from ear to ear - they are 45 degrees anterior); aligned vertically
• posterior: they are 45 degrees posterior to them; aligned vertically.
• horizontal/lateral: alligned horizontally (e.g. holding a plate next to your ear or making a circle with your arms)