Ear

Question 1

What occurs in the external ear?

Answer 1

Receives sound waves

Question 2

What occurs in the middle ear?

Answer 2

Transmits sound waves from air to bone
Amplifies by bone to bone
Transmits sound to inner ear

Question 3

What occurs in the inner ear?

Answer 3

Sound waves converted to nerve impulses (transmitted to CNS via acoustic nerve)
Contains vestibular organs

Question 4

What type of epithelium is found on the PINNA?

Answer 4

Stratified keratinised epithelium

Question 5

What type of cartilage is found on the PINNA?

Answer 5

Elastic - blood supply from overlying dense connective tissue/perichondrium

Question 6

What type of glands are found in the skin of the lateral 1/3 of the external ear canal and what do they secrete?

Answer 6

Curuminous and sebaceous glands

Modified sweat glands that produce wax

Question 7

What happens to the hairs as you move medially into the external ear canal?

Answer 7

Hair is thick on the outside and becomes finer

Question 8

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

Answer 8

Skin and cartilage

Question 9

What is the medial 2/3 of the external ear canal made of?

Answer 9

Skin and bone
No hairs/cilia
No wax

Question 10

How does the skin grow in the external ear canal?

Answer 10

Grows from umbo of tympanic membrane outwards

Question 11

How is skin maintained in the external ear canal?

Answer 11

Constantly shed and renewed

Shed in lateral 1/3 of canal and trapped in wax as part of cleaning mechanism

Question 12

Why is the ear canal prone to infections?

Answer 12

Warm, wet. blinded ended

Can be bacterial or fungal

Question 13

What is bacterial otitis externa caused by?

Answer 13

Pseudomonas or staph aureus

Question 14

What are the 3 layers of the tympanic membrane?

Answer 14

Outer - continuous with skin of EAC
Middle fibrous layer
Cuboidal epithelium

Question 15

What are the contents of the middle ear?

Answer 15

Ossicular chain
Oval window
Round window
Facial nerve (chorda tympani)
Eustachian tube opening
Mastoid air cells

Question 16

What are the 3 parts of the ossicles?

Answer 16

Malleus (hammer)
Incus (anvil)
Stapes (stirrup)

Question 17

What is the function of the ossicles?

Answer 17

Conduct sound waves from tympanic membrane to inner ear via oval window
Amplification of sound
Very important in sound conduction

Question 18

What can disruption of sound conduction in the ossicles be caused by?

Answer 18

Trauma 
Bony sclerosis (otosclerosis)

Question 19

What is the process of hearing?

Answer 19

Direct sound into canal
Tympanic membrane vibrates
Ossicular chain vibrates
Transmitted to oval window of cochlea
Detected by hair cells in organ of corti
Converted to nerve impulses
Transmitted to brainstem via CN VIII

Question 20

What is the eustachian tube?

Answer 20

Tube that connects middle ear to nasopharynx

Question 21

What are the functions of the eustachian tube?

Answer 21

Pressure equalisation (gas exchange occurs, vacuum formed in middle ear, vacuum released when eustachian tube opened)
Mucus drainage

Question 22

What is acute otitis media?

Answer 22

Infection of the lining of the middle ear

Can be bacterial or viral

Question 23

What are the signs of acute otitis media?

Answer 23

Bulging red tympanic membrane
Pus in middle ear
Pain - improves with perforation of TM and pus discharge from ear

Question 24

What are complications of pus in acute otitis media?

Answer 24

Pus can also be present in the mastoid air cells which leads to mastoiditis

Question 25

What happens in otitis media with effusion?

Answer 25

Eustachian tube isn't opening = negative pressure which causes fluid being drawn in middle ear which limits mobility of ossicular chain resulting in hearing loss Occurs easily in children due to narrow eustachian tube, large adenoids at opening

Question 26

Why is otitis media with effusion an issue in children?

Answer 26

Needs to be treated because it is an important time for language learning 90% improves in 3 months If after 3 months a GROMMET may be inserted

Question 27

What is cholesteatoma?

Answer 27

Negative pressure which sucks in tympanic membrane forms retraction pocket Retraction pocket enlarges over time which results in skin no longer being able to move out = ball of keratin stuck in middle ear which slowly destroys and invades structures Can be congenital

Question 28

What are the complications of otitis media and cholesteatoma?

Answer 28

``` Problems involving: Meninges Middle cranial fossa Facial nerve Mastoid cavity Inner ear Sigmoid sinus/IJV ```

Question 29

What are the 6 segments of the facial nerve?

Answer 29

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

Question 30

What muscles of facial expression does the facial nerve give motor supply?

Answer 30

Stapedius Posterior belly of digastric Stylohyoid

Question 31

What are the 5 branches of the facial nerve?

Answer 31

``` Temporal Zygomatic Buccal Marginal mandibular Cervical ```

Question 32

What is the cochlear?

Answer 32

Organ of corti - involved in hearing Bony and membranous labyrinth Membranous labyrinth contains perilymph and endolymph

Question 33

What makes up the peripheral vestibular apparatus?

Answer 33

Utricle Saccule Semicircular canals

Question 34

What nerve supplies the inner ear?

Answer 34

Vestibulocochlear nerve (CN VIII)

Question 35

What is the role of the semicircular canals in balance?

Answer 35

Detect head rotation

Question 36

What is the role of the saccule in balance?

Answer 36

Detects linear acceleration in vertical plane

Question 37

What is the role of the utricle in balance?

Answer 37

Detects linear acceleration in horizontal plane

Question 38

What nerve supplies sensation to the middle ear?

Answer 38

Tympanic branch of glossopharyngeal nerve | = Jacobson's nerve

Question 39

What nerve supplies sensation to the posterior half of the external auditory canal?

Answer 39

Auricular branch of vagus nerve | = Arnold's nerve

Question 40

What nerve supplies the anterior half of the external auditory canal?

Answer 40

Facial nerve

Question 41

What nerve supplies the pinna?

Answer 41

Mandibular branch of trigeminal nerve