Lecture 10

Question 1

The two major functions of the ear are?

Answer 1

Balance and Hearing

Question 2

Two membranes in the ear are?

Answer 2

1. tympanic membrane

2. vestibular membrane

Question 3

What is the main function of the external ear?

Answer 3

funnel sound into external meatus to get to inner ear.

Question 4

the tympanic membrane has which of the three ossicles pushing on it creating a pressure filled space (name this space)?

Answer 4

malleus, creates pars tensa

Question 5

What is the elbow of the malleus called? this is continuous with what space?

Answer 5

umbo 
pars flaccida (not tight no pressure compared to pars tensa).

Question 6

What is the cone of light a reflection of?

Answer 6

tympanic membrane. if infected it wont be shiny and we wont see reflection.

Question 7

Which CN passes through the superior portion of the tympanic membrane?

Answer 7

CN7

Question 8

Middle and internal ear located in what part of temporal bone?

Answer 8

petrous

Question 9

Which two nerves are located in the middle ear? they are branches of?

Answer 9

tympanic nerve (branch of CN9, breaks into tympanic plexus and lesser petrosal both run through ear) and chorda tympani nerve (branch of CN7).

Question 10

What are the two cavities in the middle ear?

Answer 10

tympanic cavity (lower) and epitympanic recess (upper).

Question 11

Base of stapes presses against what?

Answer 11

oval window.

Question 12

Head of malleus articulates with? tail of incus articulates with?

Answer 12

body of incus.

head of stapes.

Question 13

Order of ossicles outer to inner? function of ossicles?

Answer 13

MIS

transmit and amplify sounds.

Question 14

Chorda tympani nerve runs over what structure in the ear? because of this where should surgeons cut into ear to prevent hitting any nerves?

Answer 14

top of tympanic membrane. surgeons should cut from bottom up.

Question 15

Tensor tympani muscles of ear innervated by which nerve? function?

Answer 15

CNV3.

located on tympanic membrane, when contracted it dampens amplification of sound.

Question 16

Stapedius muscles innervated by which nerve? function and location?

Answer 16

innervated by CN7. located on stapes and when contracted it reduces transmission of sound to inner ear. i.e. if a sound is too loud, stapedius will contract and dampen sound.

Question 17

Auditory tube connects what to what? main function? how does it do this?

Answer 17

tympanic cavity to nasopharynx.
equalizes pressure. it can be done by two ways 1. lift auditory tube up by contracting levator veli palatini. 2. open tube by contracting tensor veli palatini.

Question 18

What are the three main structures of the inner ear? what are all three structures located in?

Answer 18

vestibule, cochlea and semicircular canals. 
otic capsule (dense bone in petrous temporal bone).

Question 19

What is the bony labriynth?

Answer 19

fluid filled space inside the otic capsule.

Question 20

What are membranous labyrinth?

Answer 20

communicating sacs and ducts suspended in bony labyrinth. inner tube filled with endolymph and these bath in perilymph. continous with three structures of inner ear.

Question 21

cochlear aqueduct is an opening into what?

Answer 21

subarachnoid space in brain

Question 22

cochlea does how many turns before it reaches dead end (this is called?)?

Answer 22

2 and a half turns until it hits apex helicotrema (channels communicate here) and then it goes back.

Question 23

Once sound waves hit round window (from stapes) where are vibrations transmitted too? vibrations are transmitted IN to the cochlea by? transmitted OUT of cochlea by? once they hit the round window what happens to the waves?

Answer 23

perilymph..
scala tympani
scala vestibuli
dissipate.

Question 24

the round window is closed by what?

Answer 24

secondary tympanic membrane.

Question 25

Vestibule is made up of what structures?

Answer 25

1. Utricle
2. Oval Window
3. Saccule
4. Aqueduct of vestibule (continuous with posterior cranial fossa)

Question 26

Semi circular canals made up of how many canals?

Answer 26

3, all are at 90 degrees to one another (occupies three planes in space)

Question 27

What is the function of the ampulla?

Answer 27

hair movement detection, this lets the brain know what movements are taking place. there is swelling at one end of each ampulla.

Question 28

Semi circular canals open into? which communicates with what?
saccule is continuous with what?

Answer 28

utricle.
utricle communicates with saccule.
saccule continuous with cochlear duct.

Question 29

What is the maculae? innervated by what nerve?

Answer 29

specialized areas in utricle and saccule.

CN8