Session 7- Functional Anatomy and Disorders of the Ear

Question 1

what components is the temporal bone made up of

Answer 1

squamous part
petromastoid part
tympanic plate
styloid process

Question 2

where are the middle and inner ear located

Answer 2

petrous part of temporal bone

Question 3

what is the external ear made up of

Answer 3

pinna
external auditory meatus
skin lined

Question 4

what is the middle ear made up of

Answer 4

air filled cavity

ossicles

Question 5

what is the middle ear lined with

Answer 5

resp epithelium

Question 6

what is the inner ear made up of

Answer 6

cochlea

semicircular canals

Question 7

what fills the middle and inner cavity

Answer 7

middle- air

inner - fluid

Question 8

what carries general sensation from ear implications for referred pain from the middle and external ear

Answer 8

C2 C3
Vagus
Trigeminal
Glossopharyngeal

Question 9

non-otological causes of otalgia

Answer 9

TMJ dysfunction
diseases of oropharynx
disease of larynx and pharynx

Question 10

function of external ear

Answer 10

collects, transmits and focuses sound waves onto the tympanic membrane

Question 11

what is a pinna haemotoma

Answer 11

accumulation of blood between cartilage and its overlying perichondrium

Question 12

how do you get a pinna haemotoma

Answer 12

trauma

subperichondrial haemotoma reduces blood supply to cartilage and causes pressure necrosis of tissue

Question 13

what can an untreated pinna haematoma lead to

Answer 13

cauliflower deformity

fibrosis-> new asymmetrical carilage

Question 14

how long is the external auditory meatus

Answer 14

2.5cm

Question 15

what lines the external acoustic meatus

Answer 15

keratinising stratified squamous epithelium

hair, sebacous glands and ceruminous glands line cartilage except on the bony part

Question 16

how does the external acoustic meatus self clean

Answer 16

desquamation and skin migration laterally off tympanic membrane out of canal

Question 17

otitis externa

Answer 17

inflammation of external ear

Question 18

what is malignant otitis externa

Answer 18

rare serious life threatening

Question 19

how does otitis media affect the tympanic membrane

Answer 19

buldging

Question 20

how does otitis media with effusion affect the tympanic membrane

Answer 20

retracted and evidence of fluid in middle ear

Question 21

how does a cholesteatoma form

Answer 21

retraction of pars flaccida |(TM) forms a sac/ pocket

• traps stratified squamous epithelium and keratin
• proliferates forming cholesteatoma

Usually secondary to chronic eustachian tube dysfunction

Question 22

what causes a cholesteoma

Answer 22

chronic eustachian tube dysfunction

Question 23

dangers of a progressing cholesteatoma

Answer 23

enzymatic bone destruction

Question 24

function of ossicles

Answer 24

amplify and relay vibrations from the TM to the oval window of the cochlea
-transmitting vibration to waves in a fluid medium

Question 25

what tampers ossicle movement

Answer 25

tensor tympani and stapedius

-contract if excessive vibration due to loud noise

Question 26

what is otosclerosis

Answer 26

ossicles fused at articulations due to abnormal bone growth particular between base plate of stapes and oval window

Question 27

function of pharyngotympanic tube

Answer 27

equilibrates pressure of middle ear with atmospheric pressure

allows for ventilation of and drainage of mucous from the middle ear

Question 28

what causes otitis media with effusion

Answer 28

Eustachian tube dysfunction

• decreases motility of TM and ossicles -> affecting hearing
• the increase in pressure in outer ear drains fluid and tympanic membrane into middle ear

Question 29

consequences of otitis media with effusion

Answer 29

may persist and/or impede speech and lamguage development/ school performance

Question 30

how do you treat otitis media with effusion

Answer 30

require grommets - tympanostomy tube

acts to maintain equillibration of pressures

Question 31

acute otitis media

Answer 31

acute middle ear infection

Question 32

signs and symptoms of acute otitis media

Answer 32

otalgia
red +/- bulging TM and loss of normal landmarks
temperature

Question 33

bacterial causes of acute otitis media

Answer 33

streptococcus pneumoniae

Haemophilus influenzae

Question 34

how does the pharyngotympanic tube differ in infants and what are the consequences of this

Answer 34

shorter and more horizontal

• easier passage for infection from the nasopharynx to the middle ear
• tube can block more easily compromising ventiation and drainage of middle ear increasing risk of middle ear infection and glue ear

Question 35

complications of acute otitis media

Answer 35

tympanic membrane perforation
facial nerve involvement

rare and life threatening

• mastoiditis
• meningitis
• sigmoid sinus thrombosis
• brain abcess

Question 36

mastoiditis

Answer 36

middle ear cavity communicates via mastoid antrum with mastoid air cells

provides a potential route for infections to spread into mastoid bonw

Question 37

how does the cochlea alow heating

Answer 37

fluid movement at the footplate of the stapes leads to a wave of movement of fluid within the cochlea coverted to action potentials which are percieved as sound

Question 38

how is the vestibular apparatus involed in balance and sense

Answer 38

fluid movement converted into action potentials -> percievd as position sense and balance

Question 39

what is the cochlea

Answer 39

fluid-filled tube with speacialised hair cells that generate action potentials when moved

Question 40

how do we hear

Answer 40

auricle and external auditory meatus focuses and funnels sound waves towards tympanic membrane which vibrates

vibration of the ossicles sets up vibrations in cochlear fluid

sensed by stereocilia in the cochlear duct

movement of the stereocilia in organ of corti trigger action potentials in cochlear part of CN VIII

primary auditory cortex

Question 41

presbycussis

Answer 41

• sensorineural hearing loss associated with old age

- bilateral and graudal

Question 42

benign paroxysmal positional vertigo

Answer 42

vertigo only

short lived episodes triggered by movement of head

Question 43

Meniere’s disease

Answer 43

vertigo, hearing loss and tinnitus

hearing loss over time

symptoms longer lasting

Question 44

acute labrynthitis or acute vestibular neuronitis

Answer 44

history of URT infections

AL= involvement of all inner ear structures, associated with hearing loss/ tinnitus and vertigo

AVN= usually no hearing disturbances or tinnitus
-sudden onset of vomiting and severe vertigo

Question 45

conductive hearing loss

Answer 45

pathology involving the external and middle ear

• wax
• otitis media (with effusion)
• otosclerosis

Question 46

sensorineural hearing loss

Answer 46

pathology involving the inner ear structures

• presbycusis
• noise related hearing loss
• meniere’s disease
• otoxic medications
• acoustic neuroma

Question 47

what is the most likely causative agent in ototis externa

Answer 47

pseudomanas aerugenosa

Question 48

how does otitis externa present

Answer 48

otalgia
discharge
itching
inflamed narrow ear canal

Question 49

which nerves carry general somatic sensation from the external ear

Answer 49

c2

mandibular division of trigeminal

vagus

facial