Anatomy and Physiology of the Ear

Question 1

Parts of the ear

Answer 1

External
Middle
Inner

Question 2

What makes up the external ear?

Answer 2

Pinna / auricle

External auditory canal

Question 3

What epithelium is on the pinna?

Answer 3

Stratified keratinised epithelium - skin

Question 4

What is the pinna made up from?

Answer 4

Elastic cartilage

Question 5

How long is the external ear canal in adults?

Answer 5

4cm

Question 6

What is the later 1/3rd of the external ear canal made up from?

Answer 6

Skin and cartilage

Question 7

What does the skin of the external ear canal contain? What is the function of this?

Answer 7

Cerminous and sebaceous gland. They produce wax

Thick hairs on the outside, becoming thinner on the inside

Question 8

Function of the external ear canal

Answer 8

Protective barrier

Disinfectant

Question 9

What is the medial 1/3rd of the ear made up from?

Answer 9

Skin and bone

Question 10

Does the medial 1/3rd of the ear produce wax?

Answer 10

No

Question 11

Does the medial 1/3rd of the ear have hairs or cilia?

Answer 11

No

Question 12

What is a feature of the growth of the skin of the external ear canal?

Answer 12

Constantly being shed and renewed
Grows from the umbo of the tympanic membrane outwards
Shed in the lateral 1/3rd of ear canal and trapped in wax as part of a cleaning mechanism

Question 13

Is the human pinna good at sound localisation?

Answer 13

No

Question 14

What are the 3 layers of the tympanic membrane?

Answer 14

Outer layer
- continuous with skin of EAC
Middle fibrous layer
Inner layer of respiratory epithelium

Question 15

What is the inner layer of respiratory epithelium?

Answer 15

Ciliated columnar epithelium with goblet cells

Question 16

What is the diameter of the tympanic membrane?

Answer 16

1cm

Question 17

How thick is the tympanic membrane?

Answer 17

1/10th of a millimetre

Question 18

Function of the ossicles

Answer 18

Conduct sound waves from the tympanic membrane to the inner ear

Question 19

What can cause disruption to the sound conduction via the ossicles?

Answer 19

Trauma

Bony sclerosis

Question 20

What is the middle ear lined with?

Answer 20

Continous respiratory epithelium that forms the inner layer of the tympanic membrane

Question 21

Can the middle ear produce mucus? What is the clinical relevance of this?

Answer 21

Yes

Glue ear

Question 22

How does the middle ear connect to the mastoid system?

Answer 22

Aditus

Question 23

How does the middle ear connect to the nasopharynx?

Answer 23

Eustachian tube

Question 24

What are the order of the ossicles from tympanic membrane to the oval window, and what is a pneumonic to remember this?

Answer 24

Malleus
Incus
Stapes

MIS

Question 25

What nerve is found in the middle ear?

Answer 25

Chorda tympani (facial nerve)

Question 26

What are the most important relations of the middle ear?

Answer 26

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

Question 27

What are the 6 segments of the facial nerve?

Answer 27

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

Question 28

What cranial nerve is the facial nerve?

Answer 28

CN VII

Question 29

Definition of otitis media

Answer 29

Infection of the middle ear that causes inflammation and a build up of fluid behind the eardrum

Question 30

Definition of cholesteatoma

Answer 30

An uncommon abnormal condition of keratinised squamous epithelium in the wrong place - can grow and become destructive

Question 31

What makes up the inner ear?

Answer 31

Bony and membranous labyrinths Chochlea Peripheral vestibular apparatus Vestibulocochlear nerve

Question 32

What do the membranous labrinths of the inner ear contain?

Answer 32

Fluid - perilymph - endolymph

Question 33

What is the cochlea?

Answer 33

The organ of hearing

Question 34

What are the peripheral vestibular apparatus?

Answer 34

Utricle Saccule Semi-circular canals

Question 35

What cranial nerve is the vestibulocochlear nerve?

Answer 35

CN VIII

Question 36

Function of the middle ear

Answer 36

Transduce vibration into nervous impulses

Question 37

What vibrates into the oval window?

Answer 37

Stapes

Question 38

What are responsible for detecting head rotation?

Answer 38

Semi circular canals

Question 39

What is the vestibulo-ocular reflex?

Answer 39

Able to fix your vision on an object even when your head is moving

Question 40

What does the saccule detect?

Answer 40

Linear acceleration in a vertical plane

Question 41

What does the utricle detect?

Answer 41

Linear acceleration in a horizontal plane

Question 42

What provides sensory innervation to the middle ear?

Answer 42

Tympanic branch of glossopharyngeal nerve

Question 43

What provides sensation to the posterior half of the external ear canal?

Answer 43

Auricular branch of vagus nerve

Question 44

What provides sensation to the anterior half of external auditory canal?

Answer 44

Facial nerve

Question 45

What provides sensation to the pinna?

Answer 45

Mandibular branch of trigeminal nerve

Question 46

What symptom is worrying in the absence of obvious ear cause?

Answer 46

Otalgia

Question 47

Definition of otalgia

Answer 47

Ear ache

Question 48

What makes up the external ear?

Answer 48

Pinna | External auditory canal

Question 49

What makes up the middle ear?

Answer 49

Tympanic membrane | Ossicles

Question 50

Parts of the tympanic membrane

Answer 50

Crus of the incus Light cone Manubrium of the malleolus Umbo of the malleolus

Question 51

What drugs taken in high doses can cause tinnitus?

Answer 51

Aspirin | NSAIDs