Session 7: Functional Anatomy And Disorders Of The Ear

Question 1

Why might otalgia be referred pain?

Answer 1

The ear has a diverse sensory innervation so may share similar innervation to other local structures

Question 2

Which bone of the skull is the ear found on?

Answer 2

Petrous part of the temporal bone

Question 3

What does the external ear consist of?

Answer 3

Pinna, external auditory meatus, lateral surface of the tympanic membrane

Question 4

What does the external ear do?

Answer 4

Collects, transmits and focuses sound waves onto the tympanic membrane

Question 5

What is the pinna made of?

Answer 5

Cartilage, skin and fatty tissue

Question 6

What causes Ramsey Hunt syndrome?

Answer 6

Shingles of the facial nerve (reactivation within the geniculate ganglion)

Question 7

What is a pinna haematoma?

Answer 7

Accumulation of blood between cartilage and perichondrium of the pinna

Question 8

What is the treatment of a pinna haematoma?

Answer 8

Prompt drainage and re-apposition of the two layers

Question 9

What is the cauliflower deformity of the ear?

Answer 9

An untreated pinna haematoma leading to fibrosis and asymmetrical cartilage development of the pinna

Question 10

What is the shape of the external acoustic meatus?

Answer 10

Sigmoidal

Question 11

Why does the ear canal have hairs and wax?

Answer 11

Prevents entry of objects and also aids desquamation

Question 12

How long is the external acoustic meatus?

Answer 12

2.5cm

Question 13

How is a perforated tympanic membrane treated?

Answer 13

It will resolve itself over time

Question 14

What is the middle ear?

Answer 14

An air filled cavity with the 3 ossicles

Question 15

What do the ossicles do?

Answer 15

Amplify vibrations from the tympanic membrane to the oval window of the cochlea

Question 16

What are the 3 ossicles?

Answer 16

Malleus, incus and stapes

Question 17

How does stapedius affect hearing?

Answer 17

Contracts if there is a potentially excessive vibration from a loud noise

Question 18

What nerve supplies stapedius?

Answer 18

Nerve to stapedius (branch of CN VII)

Question 19

What is hyperacusis?

Answer 19

Damage to nerve to stapedius causing loss of the protective acoustic reflex

Question 20

What is otosclerosis?

Answer 20

Fusion of ossicles at the articulating points

Question 21

Where is the most common site for otosclerosis?

Answer 21

Between the base plates of stapes and the oval window

Question 22

How does otosclerosis cause hearing loss?

Answer 22

The sound vibrations cannot be transmitted to the fluid

Question 23

Why is there negative pressure within the middle ear?

Answer 23

It’s mucous membrane is continuously reabsorbing air

Question 24

What structure allows for equilibration of pressure of the middle ear with atmospheric pressure?

Answer 24

Pharyngotympanic (or eustachian) tube

Question 25

What roles other than pressure equilibrium does the pharyngotympanic tube have?

Answer 25

Ventilation and drainage of mucus from the middle ear

Question 26

What is glue ear?

Answer 26

Build up of fluid and negative pressure in the middle ear

Question 27

What causes glue ear?

Answer 27

Dysfunction of the Eustachian tube

Question 28

How do you treat glue ear?

Answer 28

If doesn’t resolve spontaneously in 2-3months then use a grommet yo ventilate the middle ear

Question 29

Why are infants more likely to suffer from acute otitis media?

Answer 29

Have a shorter and more horizontal Eustachian tube (easier to block + pass infection from nasopharynx to ear)

Question 30

What are mastoid air cells?

Answer 30

Air filled cavities allowing for communication between the middle ear cavity and the mastoid antrum

Question 31

What nerve is closely associated with the middle ear?

Answer 31

The facial nerve and its branch, the chorda tympani

Question 32

What is a cholesteatoma?

Answer 32

An abnormal skin growth growing into the middle ear, behind the tympanic membrane

Question 33

What is a long term problem of cholesteatoma?

Answer 33

Erosion of structures (eg. Ossicles, mastoid, cochlea) as it grows and expands

Question 34

What are the common symptoms of cholesteatoma?

Answer 34

Painless but can get smelly otorrhea

Question 35

What causes cholesteatoma?

Answer 35

Secondary to Eustachian tube dysfunction or chronic/recurring ear infections

Question 36

What is in the inner ear?

Answer 36

Vestibular apparatus and the cochlea

Question 37

What is the vestibular apparatus responsible for?

Answer 37

Maintaining our sense of position and balance

Question 38

What does the cochlea do?

Answer 38

Converts vibrations into an action potential to be perceived as sound

Question 39

How is a action potential generated in the cochlea?

Answer 39

Sterocilia are moved by movements of fluid within the cochlea (set up by movements at the oval window)

Question 40

What is the location of the sterocilia of the cochlea called?

Answer 40

The spiral organ of corti

Question 41

What is the vestibular apparatus made up of?

Answer 41

Semicircular ducts, the saccule and urtricle

Question 42

What causes vertigo?

Answer 42

Inappropriate movement of fluid in the vestibular apparatus causing movement of the hair cells

Question 43

How do the semicircular canals help perceive balance and position?

Answer 43

They are arranged in three planes so can give the orientation of the head

Question 44

Where is the tuning fork held in Rinne’s test?

Answer 44

In front of the ear and then held against the mastoid bone

Question 45

Where is the tuning fork held in Weber’s test?

Answer 45

In the midline on the top of the head

Question 46

What results will be found in sensorineural hearing loss for Rinne’s test?

Answer 46

Air will give better conduction than bone

Question 47

What results are found for conductive hearing loss in Rinne’s test?

Answer 47

Bone will conduct sound better than air

Question 48

What result is found for conductive hearing loss in Weber’s test?

Answer 48

You can hear louder in the affected ear

Question 49

What result is found in Weber’s test for sensorineural hearing loss?

Answer 49

You can hear the sound better in the unaffected ear

Question 50

What regions of the ears are affected in conductive hearing loss?

Answer 50

External or middle ear

Question 51

What regions of the ear are affected in sensorineural hearing loss?

Answer 51

Inner ear structures or CN VIII