Wed fitz ear prerecorded lecture

Question 1

4 nerves that innervate pinna

Answer 1

great auricular
auricular branch of vagus
auriculotemporal branch of V3
lesser occipital

Question 2

special glands in the ear canal. how do they work

function of what they make?

Answer 2

ceruminous glands

combine sebaceous fluid with aqueous fluid to make cerumen.

thought to be antimicrobial

Question 3

how does conductive hearing loss come about

Answer 3

when the tympanic membrane doesn’t work

e.g. you pushed wax up against it.

Question 4

lowest point of concavity of the tympanic membrane

Answer 4

umbo

Question 5

two primary components of middle ear

Answer 5

ossicles - bones that connect the tympanic membrane to the oval window of the middle ear. physical connection that allows the transmission of sound from the tympanic membrane to the cochlea.

z

Question 6

3 main parts of the ossicle bones

Answer 6

malleus, incus, stapes.

stapes attaches to the oval window of the middle ear

Question 7

two muscles that connect to ossicle bones

what do they do

innervation?

Answer 7

tensor tympani - connects to malleus. innervated by V3

Stapedius - facial nerve

makes ossicle bones tense, harder to vibrate.

involved in the sound reflex: they effect middle ear transmission, may be involved in protection

Question 8

auditory tube

Answer 8

connects to pharynx, keeps air pressure equal between external autidory canal and the middle earspace

Question 9

Main function of the middle ear

3 mechanisms of this

Answer 9

AMPLIFIES VIA IMPEDENCE MATCHING

(minimize loss of energy that occurs at and air to water interface. (cochlea is full of fluid) normally water reflects 99.9% of sound that hits it (40-55dB))

40-55 Db is the loss in hearing of someone with conductive hearing loss.

1 - tympanic membrane&raquo_space;> oval window, all the forces applied to the tympanic membrane is transferred to a smaller window amplifying the sound

2 - malleus lever arm&raquo_space;> incus

3 - tympanic membrane buckles, force concentrated at umbo

Question 10

what physical characteristics of the middle ear determine the mass and stiffness of it?

Answer 10

mass - bones (mass transmits low pitch, inhibits high pitch)

stiffness - volume of air space (transmits high pitch, inhibits low pitch)

Question 11

two labyrinths of the inner ear and what they contain

Answer 11

bony labyrinth - contains Na rich perilymph

membranous labyrinth (inner labyrinth) - contains unique K rich endolymph. hair cell apical surface is in the endolymph. Doesn’t open out into anything - is completely enclosed.

Question 12

cochlear aquduct

Answer 12

connects perilymph to the csf, mechanism for communication of menengitis to move from the inner ear to the CSF and vice-versa

Question 13

scala media

Answer 13

where the cochlear duct is in the membranous labyrinth

Question 14

where do the semicircular canals come off of?

Answer 14

the utricle

Question 15

the 6 receptive areas in the inner ear and where are they found

Which deals with hearing, which with balance

Answer 15

3 cristae ampularis - semicircular canals
balance

2 maculae - one in saccule and one in utricle
balance

1 organ of corti - cochlea
hearing

Question 16

vestibulocohclear nerve

functions

branches?

Answer 16

sensory afferents to brainstem to hair cells (esp type 1)

motor efferents from brainstem to hair cells (type 2)

1 - auditory (cochlea)
2 - superior vestibulo (utricles, anterior and lateral semicircular canals)
3 inferior vest. (sacule)
4 - posterior vest. (posterior SC canal)

Question 17

where do efferent signals of type 1 hair cells go?

Answer 17

to the dendrites.

Question 18

function of the adaptation motor in the inner ear

Answer 18

keeps tension in the ear so that you can hear really quiet stuff (keeps hyperpolarization possible)

Question 19

Where are hair cells found in the semicircular canal?

Answer 19

in the ampula, coming off the ampulary crest, which is a bony protrusion. the cupula is above them

Question 20

in what types of hair cells are kinocilium located?

Answer 20

vestibular hair cells

Question 21

what types of hair cells have a calyx and what does it do?

Answer 21

type 1, it is the nerve endings of the primary afferent nerves. provides a secure route of info transfer

Question 22

how does the vestibular system in the ear detect acceleration?

Answer 22

when the hair cells and the cupula are at different positions, that is when you head is accelerating (hair cells more faster than the cupula, but the cupula eventually catches up when you reach a constant velocity.)

Question 23

what are the otolith organs and what do they do?

What is the middle of the organs called? orientation of things on both sides of this

Answer 23

utricle and saccule - respond to gravity, tells where you head is in space

saccule: steriocilia are orientated horizontally, they can tell if you are right side up or upside down.

Utricles are oriented downwards, they can tell if you tilt your head

middle is called the striola - in the saccule the steriocilla are orientated away from it. in the utricle they are orientate towards it

Question 24

function of otoconia

Answer 24

pull on the steriocilia in the otolith due to gravity pulling on them. made of calcium carbonate.

Question 25

what are the “threads” of the cochlea called and what are the components of it? what fluid do they contain?

Answer 25

spiral lamina, 3 components

scalae vestibulae (this is nearest to the "tip of the screw") pressure waves go up here
scalae tympani pressure waves go back down here
have perilymph

scalae media
has endolymph

Question 26

membranes that separate the scalae in the cochlea

Answer 26

Basilar - scalae tympani and media

vestibular - scalae vestibulae and media

Question 27

Where do the nerves in the cochlea run and where do they terminate

Answer 27

run up the center of modiolus to get to the hair cells in the basilar membrane

Question 28

What membrane in the cochlia vibrates when a sound is heard?

in what organ is this membrane located?

membrane on the top of hair cells in the cochlea?

What vibrates and what doesn’t?

Answer 28

basilar - vibrates

organ of corti

tectorial membrane - doesn’t vibrate

Question 29

what structure of cells produces endolymph?

Answer 29

stria vascularis

Question 30

dieter cell

Answer 30

underneath the outer hair cell, contributes a process to the reticular lamina