Physiology of Hearing and Balance

Question 1

what is the tympanic membrane to oval window ratio?

Answer 1

18:1

Question 2

what is the resting state of the eustachian tube closed by?

Answer 2

by tensor veli palatini and levator palatine musles

Question 3

what does dysfunction in the eustachian tube lead to?

Answer 3

middle ear negative pressure, can lead to fluid in the ear

Question 4

what are the 2 openings of the cochlear to the middle ear?

Answer 4

oval window and round window

Question 5

what is suspended between the scala tympani and the scala vestibuli (perilymph)?

Answer 5

scala media (endolymph)

Question 6

what is inside the scala media (endolymph)?

Answer 6

organ of corgi

Question 7

what does the organ of corgi contain?

Answer 7

hair cells

Question 8

what do the hair cells in the organ of corgi sit on?

Answer 8

the basilar membrane

Question 9

how are the hair cells in the basilar membrane arranged?

Answer 9

arranged in height order with tip links connecting them

Question 10

in which direction must the hair cells be moving if depolarisation is occuring?

Answer 10

deflecting towards the longest side of the arrangement of hair cells

Question 11

if there is hyperpolarisation of the hair cells, what way will they be moving?

Answer 11

deflecting away from the longest side

Question 12

what does the pneumonic ‘E.coli’ stand for in terms of the primary auditory cortex?

Answer 12

E- eight cranial nerve
C- cochlear nerve
O- superior Olivary complex
L- lateral lemniscus 
I- inferior colliculus

Question 13

what are the 5 key vestibular end-organs?

Answer 13

• maculae of the utricle
• maculae of the saccule
• ampullae of lateral, posterior and superior semicircular canals

Question 14

what are the utricle and saccule called collectively?

Answer 14

otolith organs

Question 15

the maculae of the otolith organs have stereocilia that project towards into what?

Answer 15

project upwards into a gelantinous matrix with otoconia

Question 16

what do the stereocilia of the otolith organs perceive?

Answer 16

movements when tilting the head or travelling in an elevator - linear motion

Question 17

when does the firing stop from the stereocilia of the otolith organs?

Answer 17

when movement stops

Question 18

what makes up the otoconia?

Answer 18

calcium carbonate crystals

Question 19

what is the orientation of the otolith organs?

Answer 19

360 orientation to detect all motion

Question 20

what is the orientation of the semi-circular canals?

Answer 20

orientated at 90 degrees to each other

Question 21

what semi-circular canal is on the same plane as the right anterior semi circular canal?

Answer 21

the left posterior

Question 22

where in the semi-circular canal does the cupula sit?

Answer 22

in the ampulla of the semi circular canals

Question 23

what does deflection cause in the semi-circular canals?

Answer 23

movement of perilymph

Question 24

what does bending cause the stereocilia to do?

Answer 24

deflect

Question 25

what plane does nystagmus happen in?

Answer 25

in the plane of the canal that is being stimulated

Question 26

what is a vestibular schwannoma?

Answer 26

tumour of the VIII nerve sheath (schwann) cells