The Ear

Question 1

List the structures sound waves pass through before reaching auditory receptors

Answer 1

0) Pina captures sound and funnels it into auditory canal
1) Auditory canal
2) Tympanic membrane
3) Ossicles
4) Oval window
5) Cochlear duct
6) Spiral organ

Question 2

What is the function of the tympanic membrane?

Answer 2

• Transmit sound from air to ossicles in middle ear/oval window.
• Vibrates in response to percussion from compressed sound waves

Question 3

What is the function of the ossicles?

Answer 3

• Vibrations translated into fluid waves

- Transmit & amplify vibrations of the tympanum across middle ear

Question 4

What is the function of the oval & round window?

Answer 4

O=Connects ossicles to cochlear

R= Moves out allowing fluid movement within the cochlear

Question 5

What is the function of the auditory tube? (also known as?)

Answer 5

• Eustachian tube
• Connects middle ear with nasopharynx
• Aerates middle ear system
• Clears mucus from middle ear into nasopharynx

Question 6

What is wax made up of and what produces it?

Answer 6

• External auditory canal lined by skin cells

- Sebum, sloughed off skin & secretions from cerumenous glands

Question 7

What is the function of the chords tympani & what nerve is it a branch of?

Answer 7

• Facial nerve (CN7)

- Taste innervation to anterior 2/3 of tongue

Question 8

How is the nasopharynx connected to the middle ear?

Answer 8

Antero-inferiorly by pharyngotympanic tube

Question 9

What does the tympanic membrane form the lateral wall of? What does this contain?

Answer 9

Air filled chamber- middle ear containing the ossicles

Question 10

Why is the middle ear liable to upper respiratory tract infections?

Answer 10

Lined with respiratory epithelium

Question 11

What & how is the middle ear connected posteriorly?

Answer 11

• Connected to mastoid air cells

- Through mastoid antrum/aditus of mastoid antrum

Question 12

What is the nerve supply & function of tensor tympani?

Answer 12

Located in middle ear
N= Branch of mandibular nerve (V3)
F= Contraction pulls handle of malleus medially

Question 13

What is the nerve supply & function of stapedius muscle?

Answer 13

Located in middle ear
N= Branch of facial nerve
F= Contraction

Question 14

What fills the external & middle ear?

Answer 14

Air

Question 15

What happens to sound in the external, middle and inner ear?

Answer 15

E= Sound waves enter ear
M= Sound converted to mechanical movement
I= Mechanical converted to electrical impusle

Question 16

Why is the middle ear a high risk space?

Answer 16

• Connected to nasopharynx: Prone to infection
• Connected to mastoid air cells: Infection passed to middle cranial fossa
• Internal Jugular inferior: Thrombus risk
• Carotid anterior: Pulsatile tinnitus
• Traversed by cochlea & facial nerve: Spread infection

Question 17

Describe the auditory pathway

Answer 17

• Bilateral: Compares 2 inputs of timing & loudness

- Polysynaptic