H&N13 - Functional Anatomy & Disorders of the Ear

Question 1

6 signs and symptoms of ear disease

Answer 1

1. ) Otalgia - ear pain
2. ) Tinnitus - ringing in ears
3. ) Discharge - ottorhoea
4. ) Vertigo - loss of balance
5. ) Hearing Loss - conductive or sensorineural
6. ) Facial Nerve Palsy

Question 2

5 nerves carrying general sensation to the ear

Answer 2

1. ) Trigeminal (CN V) - auriculotemporal nerve from the mandibular branch (Vc)
   - lateral surface of tympanic membrane, external acoustic meatus
2. ) Facial (CN VII) - nervus intermedius
   - lateral surface of tympanic membrane, external acoustic meatus, concha
3. ) Glossopharyngeal (CN IX) - tympanic nerve
   - medial surface of tympanic membrane, middle ear cavity, mastoid air cells
4. ) Vagus Nerve (CN X)
   - lateral surface of tympanic membrane, external acoustic meatus, concha

5.) C2/C3 Spinal Nerves - lesser occipital nerve (superior pinna) and great auricular nerve (majority of pinna)

Question 3

Function of the external ear

3 structures of the external ear

Answer 3

Function - collects, transmits and focuses sound waves onto the tympanic membrane

1. ) Pinna - visible part of the ear (auricle)
   - made up of cartilage, skin, and fatty tissue
   - abnormalities can be congenital, inflammatory/infective (perichondritis) or traumatic (haematoma)
2. ) External Acoustic Meatus - sigmoid shaped pathway running from the pinna to the lateral surface of the tympanic membrane
3. ) Tympanic Membrane (eardrum) - transmits sound vibrations from outer air to the auditory ossicles

Question 4

5 features of a pinna haematoma

Definition
Cause 
Type of Haematoma
Complication/Deformity
Treatment

Answer 4

1.) Definition - accumulation of blood/serum between cartilage and its overlying perichondrium

2. ) Cause - secondary to blunt injury to pinna
   - common in contact sports
3. ) Type of Haematoma - subperichondrial haematoma
   - deprives cartilage of blood supply causing avascular necrosis of tissue
4. ) Complication - cauliflower deformity
   - untreated leads to fibrosis –> new asymmetrical cartilage development
5. ) Treatment - drainage and re-accumulation of 2 layers
   - aspirate, compression bandage
   - review in 24hrs, I and D if it reaccumulates

Question 5

3 features of the external acoustic meatus

Epithelium
Structure
Common Conditions

Answer 5

1. ) Epithelium - keratinised, stratified squamous
   - epithelial migration provides self-cleaning function
   - desquamation and skin migration laterally off tympanic membrane and out of canal
2. ) Structure - outer 1/3 is cartilaginous and contains:
   - hair, sebaceous and ceruminous glands (ear wax) to form barrier to foreign objects
   - inner 2/3 is bony and has no hair and glands
3. ) Common Conditions
   - wax/foreign bodies
   - otitis externa (inflammation)

Question 6

3 common abnormalities of the tympanic membrane

Answer 6

1.) Bulging - caused by bacterial acute otitis media

2. ) Retraction and Fluid Accumulation - fluid and -ve pressure in the middle ear decreases mobility of TM and ossicles which affects hearing
   - caused by otitis media w/ effusion

3.) Cholesteatoma - abnormal skin growth behind the tympanic membrane

Question 7

4 features of a cholesteatoma

Mechanism
Cause
Symptoms x3
Complication

Answer 7

1. ) Mechanism - retraction of pars flaccida of the TM forms a pocket, trapping epithelium and keratin
   - proliferation of this forms a cholesteatoma
2. ) Cause - often secondary to chronic ET dysfunction
   - TM is sucked inwards due to negative pressure caused by blockage of the eustachian tube (ET)
3. ) Symptoms
   - painless, smelly otorrhoea +/- hearing loss
4. ) Complications - not malignant but slowly expands
   - can destroy structures in the middle and inner ear
   - can erode into the nearby skull and into the brain

Question 8

Function of the middle ear

2 structures in the middle ear

Answer 8

Function - amplify and relay fibrations from the TM to the oval window of the cochlea (inner ear)
- it is an air-filled cavity between the TM and inner ear

1. ) Ossicles - 3 bones (malleus, incus, stapes) that help transmit sounds to the cochlea
   - movement is dampened by stapedius muscle and tensor tympani which contract to prevent excessive vibrations (acoustic reflex)
2. ) Pharyngotympanic (Eustachian) Tube - tube that links the middle ear to the nasopharynx
   - its equilibrates the pressure of middle ear with atmospheric pressure
   - mucous membrane continously reabsorbs air in the middle ear causing negative pressure
   - allows ventilation and drainage of mucus

Question 9

3 features of otosclerosis

What is it?
Aetiology
Complication

Answer 9

1.) What is It? - fusion of ossicles at articulations

2. ) Aetiology - abnormal bone growth, particularly between the base plate of stapes and oval window
   - sound vibrations not transmitted effectively to cochlea
   - exact cause of abnormal bone growth is unknown
   - family history common
3. ) Complication - causes conductive hearing loss
   - most common cause of hearing loss in young adults

Question 10

4 features of otitis media

Acute Otitis Media (AOM)
Signs and Symptoms of AOM x3
Otitis Media w/ Effusion (‘glue ear’)
Common Demographic

Answer 10

1.) Acute Otitis Media - acute middle ear infection
- often viral infections but can be bacterial
(S. pneumoniae, H. influenzae)

2.) Signs and Symptoms - otalgia, systemic symptoms, red +/- bulging tympanic membrane

3. ) Otitis Media w/ Effusion - collection of fluid within the middle ear without signs of inflammation
   - can predispose to ET dysfunction (-ve pressure) —> cholesteatoma
   - most resolve spontaneously in 2-3 months
   - management: grommets (tympanostomy tube) to maintain equilibration of pressures
4. ) Common in Infants - ET is shorter and horizontal
   - easier passage for infection from nasopharynx
   - tube is blocked easier, compromising ventilation and drainage of mucus, increasing risk of infection and glue ear

Question 11

4 complications of acute otitis media

Answer 11

1. ) Tympanic Membrane Perforation - can lead to hearing loss and increase susceptibiltiy to infections
2. ) Facial Nerve Lesions (rare) - chorda tympani and stapedius nerve runs through the middle ear cavity
3. ) Mastoiditis - middle ear infections can spread to the mastoid bone due to communication w/ mastoid air cells
   - communication via the mastoid antrum
4. ) Intracranial Complications - spreading of infection into the skull can lead to:
   - meningitis, sigmoid sinus thrombosis, brain abscess

Question 12

2 features/structures in the inner ear

Answer 12

1.) Cochlea - fluid-filled tube w/ specialised hair cells (stereocilia) that converts fluid movement into sound

2. ) Vestibular Apparatus - fluid-filled tubes w/ stereocilia converting fluid movement into position sense/balance
   - includes semicircular ducts, the saccule and utricle
   - fluid movement due to position and rotation of head moves stereocilia which generate APs via CN VIII
   - helps to perceive and maintain our sense of balance

Question 13

5 steps/structures in allowing us to hear

External Ear
Tympanic Membrane
Ossicles
Stereocilia
Primary Auditory Cortex

Answer 13

1. ) External Ear - auricle and external auditory meatus funnels sound waves towards the tympanic membrane
2. ) Tympanic Membrane - vibrations of the tympanic membrane spreads to the ossicles
3. ) Ossicles - vibrations occur in stapes at oval window
   - sets up vibrations in cochlear fluid in the cochlear duct
4. ) Stereocilia - detect movement in cochlear fluid
   - found in a part called the spiral organ of corti
   - movement of stereocilia triggers APs in cochelar part of the vestibulocochlear nerve (CN VIII)

5.) Primary Auditory Cortex - makes sense of the input from CN VIII

Question 14

5 conditions affecting the inner ear

Presbyacusis
Benign Paroxymal Postional Vertigo
Meniere's Disease
Acute Labrynthitis
Acute Vestibular Neuronitis

Answer 14

1. ) Presbycusis - bilateral and gradual sensorineural hearing loss associated with old age
2. ) Benign Paroxysmal Positional Vertigo - short episodes (seconds) of vertigo triggered by the movement of the head

3.) Meniere’s Disease - recurrent episodes of vertigo,
unilateral hearing loss, and tinnitus, +/- nausea/vomiting
- symptoms last 30 mins up to 24 hours
- hearing deteriorates over time

4. ) Acute Labrynthitis - history of URT infection w/ vertigo, hearing loss, tinnitus and vomiting
   - involvement of all inner ear structures
5. ) Acute Vestibular Neuronitis - history of URT infection w/ severe vertigo and sudden onset of vomiting
   - usually no hearing disturbance or tinnitus

Question 15

2 types of hearing loss (and causes)

Answer 15

1. ) Conductive - caused by pathology involving the external or middle ear
   - e.g. wax, otitis media (both types), otosclerosis
2. ) Sensorineural - caused by pathology involving the inner ear or CN VIII
   - e.g. presbyacusis, Meniere’s disease, acute labyrinthitis
   - acoustic neuroma, noise-related hearing loss, ototoxic medications

Question 16

7 non-otological causes of ear pain (otalgia)

structures sharing CN sensory innervation w/ the ear

Answer 16

1. ) Nose and Sinuses - maxillary branch of trigeminal (Vb)
2. ) Teeth and TMJ - mandibular branch of trigeminal (Vc)
3. ) Parotid Gland - mandibular branch of trigeminal (Vc)
   - also the facial nerve (VII) as it runs through it
4. ) Tongue and Oropharynx - Vc (lingual branch) and IX
5. ) Larynx and Laryngopharynx - vagus nerve (X)
6. ) Oesophagus - vagus nerve (X)
7. ) Cervical Spine - C2 and C3

Question 17

Rinne’s and Weber’s Test

Answer 17

Rinne’s - tests conductive hearing (place on mastoid process)

• positive test is normal (air > bone conduction)
• negative test is abnormal ( bone > air conduction)

Weber’s - tests sensorineural and conductive hearing (place on middle of forehead)

• negative test is normal (equally loud in both ears)
• conductive: louder in impaired ear
• sensorineural: louder in unimpaired ear