(6.1) The Ears

Question 1

How can a doctor get a better look in to the ears?

Answer 1

Pull the auricle backward and downward due to the sigmoid shape of the acoustic canal.

Question 2

How does auricular haematoma cause complication?

Answer 2

Collection of blood in the auricle -> fibrosis -> deformity -> Boxer’s / Cauliflower ear

Question 3

What structure separates the outer and middle ears?

Answer 3

Tympanic membrane

Question 4

Describe the innervation of the tympanic membrane.

Answer 4

External surface: Auriculotemporal branch of Mandibular Nerve (CN Viii) + Auricular branch of Vagus Nerve (CN X) + Facial N via Auricular N
Internal surface: Tympanic plexus part of Glossopharyngeal Nerve

Question 5

What structures made up of the middle ear?

Answer 5

Ossicles: Malleus + Incus + Stapes (from external to internal)

Question 6

What does the middle ear open into anteriorly and posteriorly?

Answer 6

Anteriorly: Nasopharynx via Eustachian Tube
Posteriorly: Mastoid air cells via Mastoid Antrum

Question 7

Why do children get Otitis Media more easily?

Answer 7

Their acoustic canals are more horizontal and shorter.

Question 8

What are the complications of Mastoditis?

Answer 8

Spread to middle cranial fossa via Pterosquamous fissure

Question 9

Where in the ear does the facial nerve lie close to? Which branch does it give off to here?

Answer 9

Lies close to the middle ear.

Branches off Chorda Tympani Nerve in the Tympanic cavity.

Question 10

What is the function of Eustachian tube? What complication might it cause if it is obstructed?

Answer 10

Equalise pressure in the ear
Obstruction -> retracted Tympanic Membrane -> negative pressure in the middle ear -> fluid drawn out from the cells -> Glue Ear (otitis media with effusion) + bulged Tympanic Membrane

Question 11

What is another name given to the inner ear? What structures does it made up of? What are their functions?

Answer 11

Labyrinth
Cochlear: Hearing
Vestibule: Balancing

Question 12

What may be the problem if the vestibule becomes dysfunction?

Answer 12

Vertigo: dizziness

Question 13

What tests are used to distinguish conductive and sensorineural hearing loss?

Answer 13

Weber test: tuning fork on the forehead. Conductive loss hears louder in defected ear. Sensorineural loss hears louder in normal ear.
Rinne test: tuning fork in the air and mastoid bone. Normally hears louder in the air. Conductive loss hears louder on mastoid bone. Sensorineural loss can’t hear either.

Question 14

Which ossicle does the Tensor tympani attached to? What nerve innervates it?

Answer 14

Malleus

Mandibular branch of Trigenminal nerve.

Question 15

Which ossicle does the Stapedius attached to? What nerve innervates it?

Answer 15

Stapes

Facial Nerve

Question 16

In which bone is the middle ear located in?

Answer 16

Temporal bone - Petrous part

Question 17

What is the function of Mastoid air cells?

Answer 17

Release air into the ear when pressure is low

Question 18

What is Otosclerosis?

Answer 18

Overgrowth of bone, specifically the ossicles which can result in partial/complete hearing loss

Question 19

What ossicles are derived from Meckles’ cartilage?

Answer 19

Malleus and Incus

Question 20

What cartilage is stapes derived from?

Answer 20

Reichart’s cartilage

Question 21

What is Meniere’s disease? How could you treat it?

Answer 21

Hearing loss + tinnitus + vertigo caused by abnormal fluid and ion homeostasis in the inner ear
Treated with salt restricted diet + diuretics

Question 22

Where does the vestibulocochlear nerve divide into its consitituent nerves? Which other cranial nerve is also at this point?

Answer 22

Internal acoustic meatus

Also contains Facial nerve

Question 23

What nerves supply the outer ear?

Answer 23

Auriculotemporal (br. of CN Viii)
Auricular br of Vagus N
Branches of Cervical Plexus
Facial N via Auricular N

Question 24

What is it called if the Eustachian Tube becomes blocked?

Answer 24

Colesteatoma