Anatomy and Physiology of Hearing

Question 1

What are the 3 parts of the ear?

Answer 1

External
Middle
Inner

Question 2

What is the entire outer ear referred to as?

Answer 2

Pinna or auricle

Question 3

What type of tissue is present on the outer ear?

Answer 3

Stratified keratinised epithelium

Elastic cartilage

Question 4

What is the external ear canal comprised of?

Answer 4

Lateral 1/3 made of skin and cartilage

Medial 1/3 made of skin and bone

Question 5

What comprises the lateral 1/3 of the external ear canal?

Answer 5

Skin containing ceruminous and sebaceous glands

Thick hairs, becoming finer

Question 6

What is the role of the lateral 1/3 of the external ear canal?

Answer 6

Produces wax

Protective barrier and disinfectant

Question 7

What are the features of the medial 1/3 of the external ear canal?

Answer 7

No hairs or cilia

Doesn’t produce wax

Question 8

What can cause otitis media?

Answer 8

Staph aureus

Pseudomonis

Question 9

What groups are otitis externa more common in?

Answer 9

Swimmers

Those who use hearing aids

Question 10

Where does the skin of the external ear canal grow from?

Answer 10

Umbo of the tympanic membrane outwards

Question 11

What is pinna haematoma?

Answer 11

Blood clot pushes ear away from cartilage causing a knobbly appearance

Question 12

How is pinna haematoma treated?

Answer 12

Incision under local anaesthetic to the helix, drained and stitched up to close dead space

Question 13

What groups can malignant otitis media be more common in?

Answer 13

Elderly

Diabetics

Question 14

How is malignant otitis media treated

Answer 14

Admission for IV antibiotics

Question 15

What is the treatment for a living creature in the ear?

Answer 15

Drown in oil or water before extraction

Question 16

What is the top of the ear known as?

Answer 16

Attic

Question 17

What is the annulus?

Answer 17

Outside part of the middle ear

Question 18

What are the 3 layers of the tympanic membrane?

Answer 18

Outer layer continuous with skin of EAC
Middle fibrous layer
Inner layer of respiratory epithelium (ciliated columnar with goblet cells)

Question 19

What is the function of the ossicles?

Answer 19

Conduct sound waves from tympanic membrane to inner ear

Question 20

What can cause disruption of the ossicles?

Answer 20

Trauma 
Bony sclerosis (otosclerosis)

Question 21

What type of epithelium is found in the middle ear?

Answer 21

Ciliated columnar epithelium with goblet cells

Question 22

What does the middle ear connect to?

Answer 22

Mastoid system via aditus and nasopharynx via eustachian tube

Question 23

What does the middle ear contain?

Answer 23

Facial nerve (chords tympani)

Question 24

What are the important relations of the middle ear?

Answer 24

Middle cranial fossa
Internal carotid artery
Sigmoid sinus and internal jugular vein

Question 25

What are the 6 segments of the facial nerve?

Answer 25

``` Intracranial Meatal segment (internal auditory meatus) Labyrinthine segment Tympanic segment Mastoid segment Extratemporal segment ```

Question 26

What muscles does the facial nerve give motor supply to?

Answer 26

Stapedius Posterior belly of digastric Stylohyoid

Question 27

What does the facial nerve give taste sensation to?

Answer 27

Anteriror 2/3 of tongue from chord tympani

Question 28

What is otitis media

Answer 28

Infection of the middle ear

Question 29

What are the complications of otitis media and cholesteatoma?

Answer 29

``` Meninges Middle cranial fossa Facial nerve Mastoid cavity Inner ear Sigmoid sinus/internal jugular vein ```

Question 30

What is cholesteatoma?

Answer 30

Keratinised squamous epithelium in the wrong place

Question 31

What does the inner ear contain?

Answer 31

Bony and membranous labyrinth Conhlear Peripheral vestibular apparatus Vestibulocochlear nerve (CR N VIII)

Question 32

What does the membranous labyrinth contain?

Answer 32

Fluid (perilymph and endolymph)

Question 33

What comprises the peripheral vestibular apparatus?

Answer 33

Utricle Saccule Semicircular canals

Question 34

What is the process of hearing?

Answer 34

Foot of stapes vibrates in oval window Causes pressure wave though fluid in cochlear Detected by hair cells in organ of corti Transmitted to brainstem (junction of pons and medulla) by CR N VIII

Question 35

What is the process of balance?

Answer 35

Semicircular canals detect head rotation Saccule detects linear acceleration in vertical plane Utricle detects linear acceleration in horizontal plane

Question 36

What nerve provides sensation to the middle ear?

Answer 36

Tympanic branch of glossopharyngeal nerve (Jacobsons nerve)

Question 37

What nerve provides sensation to the posterior half of the EAC?

Answer 37

Auricular branch of the vagus nerve (Arnolds nerve)

Question 38

What nerve provides sensation to the anterior half of the EAC?

Answer 38

Facial nerve

Question 39

What nerve provides sensation to the pinna?

Answer 39

Mandibular branch of trigeminal nerve