Head And Neck: Anatomy Of The Ear

Question 1

What makes up the external, middle and internal ear?

Answer 1

External ear: the pinna, external acoustic meatus (ear canal) and the tympanic membrane

Middle ear: tympanic cavity, ossicles and opening to the eustachian tube

Inner ear: the bony labyrinth which contains the vestibule, semicircular ducts, canals, cochlea and spiral organ of corti

Question 2

What are the folds of cartilage called on the pinna?

Answer 2

Helix, antihelix, tragus and anti-tragus

Question 3

What is the external auditory meatus made of?

Answer 3

A cartilaginous tube laterally and a bony tube medially (temporal bone)

Question 4

How is the ear wax formed?

Answer 4

Formed from cerumen (modified sebum) along with discarded skin cells

Question 5

How can otitis media cause mastoiditis?

Why is this serious?

Answer 5

The middle ear is connected to the mastoid bone by mastoid air cells

The bone itself can be infected
The infection can spread to the meninges or the brain

Question 6

Through what structure does equalisation of air pressure occur?

Answer 6

The Eustachian tube allows equalisation of air pressure between the middle ear and the atmosphere

This is necessary for efficient transfer of sound energy to the internal ear

Question 7

Describe the 3 ossicles

Answer 7

The malleus - the handle is attached to the tympanic membrane and the body articulates with the incus

The incus - articulates with stapes

The stapes - articulates with the bony labyrinth of the internal ear via the oval window

Question 8

What types of joints are between the ossicles?

Why is this of clinical significance?

Answer 8

They are synovial joints and therefore can get osteoarthritis which causes reduced hearing

Question 9

Why can otitis media cause lesion of the facial nerve?

Answer 9

The facial nerve is only separated from the middle ear by a thin bony partition

Question 10

What is another name for the inner ear?

Answer 10

The labyrinth

Question 11

What are the 2 different regions of the inner ear?

Answer 11

The bony labyrinth surrounding the membranous labyrinth (they are separated by a fluid called perilymph)

Question 12

What is a pinna haematoma?

Answer 12

An accumulation of blood between the cartilage and perichondrium (overlying CT that is a source of blood to the avascular cartilage).

This deprives the cartilage of blood supply therefore needs prompt drainage to prevent necrosis

Question 13

What condition occurs if pinna haematoma is not treated promptly?

Answer 13

There is fibrosis and asymmetrical cartilage development - called cauliflower ear

Question 14

Why is it necessary to pull the ear up and back when examining with an otoscope?

Answer 14

To straighten the ear canal - it is usually sigmoid shape

Question 15

What is otitis externa?

Answer 15

Infection and inflammation of the ear canal - known as swimmers ear due to moisture in the ear canal predisposing to infection.
Very painful, may get a discharge from the ear. Treated with antibiotic drops +/- steroid drops

Question 16

What features of the tympanic membrane are visible using an otoscope?

Answer 16

The long process of incus and handle of malleus

A cone of light reflecting from the otoscope

The pars tensa (taught area) and the pars flaccida (less taught)

Question 17

What causes a bulging red tympanic membrane?

Answer 17

Middle ear infection

Question 18

What is the oval window?

Answer 18

The area where the stapes connects to the inner ear

Question 19

What is otitis media with effusion?

Answer 19

Also known as glue ear - not an actual infection

The eustachian tube gets blocked resulting in a build up of fluid and a negative pressure in the middle ear.
(Tympanic membrane is retracted and straw coloured)
There is decreased mobility of the tympanic membrane and ossicles so there is reduced hearing

May need grommets

Question 20

What is otitis media?

Answer 20

A middle ear infection - more common in infants

Causes pain and possible fever
The tympanic membrane is red and bulging and there is loss of normal landmarks

Question 21

Why are middle ear infections more common in infants?

Answer 21

The Eustachian tube is shorter and more horizontal therefore:

• there is easier passage of infection from the nasopharynx
• tube can bock more easily which increases risk of infection

Question 22

What are the complications of otitis media?

Answer 22

• tympanic membrane perforation
• facial nerve involvement
• mastoiditis
• meningitis
• brain abscess

Question 23

What are symptoms of mastoiditis?

What is the treatment?

Answer 23

The area of the mastoid appears red and swollen - this can push the ear forward

Will need IV antibiotics and possible surgery

Question 24

What is cholesteatoma?

Answer 24

Rare but cant be missed.

There is painless discharge
Usually due to recurrent ear infections - draws the tympanic membrane inwards and can form a small pocket

Skin cells get trapped and can grow in this pocket - slowly expands and can droid into the ossicles, mastoid, cochlea

Question 25

How does the cochlear cause hearing?

Answer 25

The cochlear is a fluid filled tube - movements at the oval window create waves of fluid which cause movement of special sensory cells (spiral organ of corti) within the cochlear duct which fire action potentials in CN8

Question 26

If there is conductive hearing loss - what will the results be of Rinne’s and Webber’s tests?

Answer 26

Webbers test: the sound will be louder on that side

Rinnes test: the sound will be louder through the mastoid bone

Question 27

If there is sensorineural hearing loss - what will the results be of Rinne’s and Webber’s tests?

Answer 27

Webbers test: the sound will be louder in the opposite ear

Rinne’s test: the sound will be louder through air

Question 28

What are the normal results of Rinne’s and Webber’s tests?

Answer 28

Rinnes: the sound should be louder through air

Webbers: the sound should be central and not louder in one ear