6.1 The Ear

Question 1

What makes up the external ear?

Answer 1

Pinna
External auditory canal
Tympanic membrane

Question 2

What makes up the middle ear?

Answer 2

Ossicles
Muscles
Eustachian tube
Mastoid air cells
Facial nerve (chorda tympani)

Question 3

What makes up the inner ear?

Answer 3

Cochlear

Vestibular compartment

Question 4

What is a pinna haematoma?

Answer 4

Haematoma between the cartilage and the perichondrium which prevents oxygenation of tissue resulting in avascular necrosis

Question 5

What is cauliflower ear?

Answer 5

Ear collapses in and structure is lost after repeated injuries (eg rugby injuries)

Question 6

Which glands form ear wax?

Answer 6

Serumium glands

Question 7

What is the function of ear wax?

Answer 7

Cleans the ear

Question 8

What is the tympanic membrane also known as?

Answer 8

Ear drum

Question 9

Which way does the cone of light point on the tympanic membrane?

Answer 9

Inferiorly and anteriorly

Question 10

Give 2 causes of tympanic membrane rupture

Answer 10

Trauma

Infection

Question 11

Name the 3 bones of the middle ear

Answer 11

Malleus
Incus
Stapes

Question 12

What type of joint joins the bones of the middle ear?

Answer 12

Synovial joint

Question 13

What is the function of the eustachian tube?

Answer 13

Equalises the pressure between the ear and the GI tract

Question 14

What is the function of the mastoid air cells?

Answer 14

Aerate the middle ear

Question 15

Name the 2 muscles in the middle ear

Answer 15

Tensor tympani and the stapedius

Question 16

What nerve innervates the tensor tympani?

Answer 16

CN V2 branch

Question 17

What nerve innervates the stapedius muscle?

Answer 17

Facial nerve

Question 18

Why are children more at risk of eustachian tube dysfunction?

Answer 18

Tube is shorter and wider and so more at risk of infections travelling up from the mouth

Question 19

What is otitis media?

Answer 19

Inflammation of the middle ear leading to retraction of the ear drum.

Question 20

What is glue ear?

Answer 20

Accumulation of thick effusions behind the ear drum

Question 21

What is mastoiditis?

Answer 21

Inflammation of the mastoid air cells. Pus forms and increases the pressure in the ear

Question 22

What is cholesteatoma?

Answer 22

Negative ear pressure causes retraction of the tympanic membrane. Dead cells accumulate as a necrotic mass (cholestoma). Lytic enzymes are released and erodes the middle ear

Question 23

What bone surrounds the inner ear?

Answer 23

Temporal bone

Question 24

Which part of the inner ear allows hearing?

Answer 24

Cochlear

Question 25

How does the cochlear work?

Answer 25

Radial structure with sensory cells. The sensory cells have a given frequency at which they will resonate. This produces an electrical signal which the brain recognises as sound

Question 26

Which part of the ear controls balance?

Answer 26

Vestibular compartment- utricle, saccule, 3 semi-circular canals

Question 27

How does the vestibular compartment control balance?

Answer 27

Fluid in the semicircular canals and the saccule moves and hits the collagenous matrix. Depending on which area of the vestibular can detect the fluid, the brain can work out its orientation

Question 28

What is BPPV?

Answer 28

Benign Positional Paroxysmal Vertigo
Extra sediment in the inner ear fluid moves slower than the fluid. Eg. When the head turns the fluid moves so the brain recognises the movement. However the sediment still moves even when the body has stopped. Person feels as if they are still moving even when they are not

Question 29

What is Meniere’s disease?

Answer 29

Too much fluid in the inner ear so everything is overstimulated