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Head and Neck > Lecture 11 - Anatomy of the ear > Flashcards

Lecture 11 - Anatomy of the ear Flashcards

1
Q

Symptoms and signs of ear disease

A 
Otalgia - ear pain 
Tinnitus
Discharge
Vertigo 
Hearing loss
Facial nerve palsy
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2
Q

2 types of hearing loss

A

Conductive - external and middle ear

Sensorineural - inner ear

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3
Q

External ear structures

A

Pinna and auricle
External auditory meatus - skin lined ear canal
Lateral tympanic membrane

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4
Q

Middle ear structures

A

Air filled cavity lined with resporatory epithelium
Ossicles

  • The pharyngotympanic tube connects it to the oropharynx
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5
Q

Inner ear structures

A

Cochlear
Semicircular canals

  • Fluid filled
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6
Q

Mastoiditis

A

Mastoid process contains mastoid air cells that communicates with the middle ear cavity via the mastoid antrum.

Potential route of infection spread from the middle ear to the mastoid air cells

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7
Q

Auricle

A

Cartilaginous
Covered in skin
Includes ear lobe
Covered in ridges - direct sound waves and guard the external acoustic meatus

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8
Q

Helix

A

Outer rim of auricle

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9
Q

Tragus

A

Small flap of auricle

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10
Q

External acoustic meatus

A

Laterally: Cartilaginous
(1/3rd) Contains hair, cerumen and sebaceous glands

Medially: Bony canal formed by the tympanic plate (2/3rd)

Most medially: fibrous tympanic membrane - ear drum

Lined by skin secreting cerumen (modified sebum) for protection

Sigmoid shape

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11
Q

Ear wax

A

Discarded skin and cerumen

Self cleaning - desquamation and skin migration laterally off the TM out of the canal

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12
Q

Ossicles

A

Malleus
Stapes
Incus

Amplify and transmit vibrations to oval window of cochlear

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13
Q

Eustachian tube (pharyngotympanic)

A

Connects the middle ear to the oropharynx and equalises pressure with the atmosphere.

Ventilates and drains mucus from the middle ear.

Potential route for infection spread from the oropharynx to the middle ear

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14
Q

Eustachian tube innervation

A

Innervated by the Glosspharyngeal nerve - an feel general sensation and pain

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15
Q

Lining of the eustachian tube

A

Lined with pseudostratified columnar epithelium

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16
Q

How does the eustachian tube open

A

Usually closed but intermittently opened by pull of muscles when swallowing and yawning

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17
Q

Special sensory nerve for hearing and balance

A

CN VIII - vestibulocochlear

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18
Q

Innervation of the ear

A

Branches of:

C2/C3:
- Pinna

Vagus nerve:

  • Lateral tympanic membrane
  • External acoustic meatus
  • Concha

Trigeminal auriculotemporal nerve (Vc):

  • Lateral tympanic membrane
  • External acoustic meatus
  • Part of tragus

Glosspharyngeal nerve (tympanic nerve):

  • Mastoid air cells
  • Middle ear
  • Medial tympanic membrane

Facial nerve (nervus intermedius) :

  • Lateral TM
  • EAM
  • Concha
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19
Q

Why do you get ear pain in pharyngitis?

A

Referred pain due to glossopharyngeal nerve

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20
Q

Otalgia with normal ear examination

A

Can have a non- ontological cause e.g.

TMJ dysfunction - CN Vc
Oropharynx disease - CN IX
Larynx/pharynx disease - CN X

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21
Q

Function of the external ear

A

Collects, transmits and focuses sound waves onto the TM

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22
Q

Pinna abnormalities

A

Ramsey Hunt syndrome - Varicella Zoster with facial nerve palsy

Pinna haematoma

Perichondritis

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23
Q

Varicella zoster

A

Vesicular rash in ear - shingles

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24
Q

Pinna haematoma

A

Accumulaton of blood between the cartilage and overlying perichondrium secondary to blunt injury to pinna

  • deprives cartilage of blood supply thus necrosis can occur
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25
Q

How to treat a pinna haematoma

A

Tamponade eitehr side of the ear so layers are together quickly

Untreated can cause fibrosis and new assymetrical carilage formation

26
Q

Cauliflower deformity

A

Untreated pinna haematoma can cause fibrosis and new assymetrical cartilage formation

27
Q

Lining of the external acoustic meatus

A

Keratinisising stratified squamous epithelium continuous onto the lateral TM

28
Q

Common abnormalities of the external acoustic meatus

A

Wax/foreign body blockage

Otitis externa

29
Q

Malignant otitis externa

A

NOT cancer
Excruciating pain
Deep pain involving bone

In diabetics and immunocompromised

30
Q

Otits externa presentation

A

Pain
Discharge
Narrow EAM
Associated with asthma and infection

31
Q

Normal tympmanic membrane

A

Apex points medially

32
Q

Bacterial acute otitis media

A

Bulging of TM towards external ear

Due to high pressure
Puss and inner ear infection

33
Q

Otitis media with effusion

A

Retracted TM and evidence of fluid within middle ear cavity due to negative pressure
Bubbles

34
Q

Cholesteatoma

A

Tretraction of pars flaccida TM forms a sac

Traps stratified squamous epithelium and keratin

Proliferated forming a cholesteatoma

Usually secondary to chronic ET dysfunction which creates negative pressure

35
Q

Cholesteatoma presentation

A 
Painless
Crusting of pars flaccida
Smelly otorrhea
\+/- hearing loss 
NOT malignant
36
Q

Serious consequence of cholesteatoma

A

Ezymatic bony destruction of ossicles, mastoid, petrous bone and cochlear

37
Q

How are the ossicles connected

A

Via synovial joints

38
Q

What muscles tamper ossicle vibration

A

Stapedius

Tensor tympani

39
Q

Otosclerosis

A

Genetic and environmental cause
Idiopathic

Ossicles fuse at articulations due to abnormal bone growth (particularly between the stapes and oval window)

Vibrations cannot be properly transmitted to the cochlea

Gradual unilateral or bilateral conductive hearing loss

40
Q

What causes negative pressure in the middle ear?

A

Mucous membrane of the middle ear reabsorbs air

41
Q

Otitis media with effusion

A
  • glue ear
  • can predispose to infection
  • due to ET dysfunction
  • fluid and negative pressure in middle ear decreases mobility of TM and ossicles
42
Q

Complications of otitis media with effusion

A

Affects hearing but may resolve spontaneously in most children

If persists and impedes speech and language development, requires grommets to maintain equilibration of pressure

43
Q

Acute otitis media presentation

A

Middle ear infection
Common in infants

  • otalgia
  • temperature
  • red +/- bulging TM
44
Q

Causes of acute otitis media

A

Viral aetiology

bacterial:
- strep pneumoniae
- Haemophilus influenzae

45
Q

Why is acute otitis media seen in infants most commonly?

A

Infants have a shorter and more horizontal eustachian tube

  • easier passage of infection
  • tube can block more easily, compromising ventilation and drainage
46
Q

Complications of acute otitis media

A
  • TM perforation due to pressure
  • Facial nerve involvement due to nerve to stapedius and chorda tympani running through the middle ear cavity
  • Mastoiditis

Intracranial:

  • Meningitis
  • sigmoid sinus thrombosis
  • brain abscess
47
Q

Cochlea

A

Endolymph filled tubes with specialised hair cells that generate APs when moved

Converts fluid movement in the cochlear duct (due to stapes vibrations on the oval window) into action potential via CN VIII cochlear part. Perceived as sound.

Movement of special sensory steriocilia into APs

Scala vestibuli
Scala media
Scala tympani

Separated by membranes

48
Q

Vestibular apparatus

A

Semicircular canals
Saccule
Utricle
(contain steriocilia)

Semicircular canals convert fluid movement generated by position and rotation of head into action potentials in CN VIII by steriocilia movement perceived as position and balance

49
Q

Inner ear disease complications

A

Hearing loss
Tinnitus
Vertigo

50
Q

How do we hear>

A
  1. Auricle focuses and directs sound waves into the external auditory canal.
  2. The waves are transmitted to the typmanic membrane and it vibrates.
  3. The ossicles vibrate in the middle ear.
  4. The stapes transmits the vibrations to the oval window of the inner ear.
  5. The vibrations are transmitted to the cochlear duct where movement of fluid is converted to APs by the steriociliar cells in the spiral organ of Corti
  6. APS in the cochlear part of CN VIII are sent to the primary auditory cortex in the temporal lobe.
51
Q

Presbycusis

A

Sensorineural loss of hearing associated with old age (natural)

Bilateral and gradual

52
Q

Benign paroxysmal positional vertigo

A
  • Vertigo only
  • Short episodes (seconds)
  • Triggered by movement of head
53
Q

Dix - Hallpike manoeuvre

A

Diagnosis benign paroxysmal positional vertigo

When lowering a patients head suddenly, they get involuntary eye movements (nystagmus)

54
Q

Epley manoeuvres

A

Dix- Hallpike manoeuvre but turn 90 degress when lying down. Feel dizzy

55
Q

Meniere’s disease

A

Vertigo, tinnutis and hearing loss usually unilateral

  • Nausea and vomiting
  • Longer lasting symptoms (30mins - 24 hours)
  • Recurrent episodes
  • hearing may deteriorate over time
56
Q

Acute labrynthitis

A

History of upper resp tract infection
Caused by virus affecting the inner ear

  • all inner ear structures affected
  • associated with hearing loss, tinnitus, vertigo and vomiting
57
Q

Acute vestibular neuronitis

A

Usually don’t get hearing loss or tinnitus

Sudden onset vomiting and severe vertigo lasting days

58
Q

Causes of conductive hearing loss

A

Wax/ Foreign object
Acute otitis media
Otitis media with effusion
Otosclerosis

59
Q

Sensorineural hearing loss causes

A 
Presbyacusis
Noise- related hearing loss
Meniere's disease 
Ototoxic medications
Acoustic neuroma
60
Q

Weber’s test

A
  1. Place tune fork on top of head in midline
  2. Vibrations send sound through bone to the cochlea equally on both sides

External ambient noises mask fork input

If conductive - will hear sound louder on affected side

If sensorineural - Will hear sound louder on normal sound

61
Q

Rinne’s test

A

Sound conducted through air (external and middle ear) is louder than through bone

  1. Place fork on mastoid process therefore vibrations directly to inner ear
  2. Place fork in front of the external acoustic meatus (normal pathway of sound)
    - ve result - sound will be heard louder when at mastoid process due to conductive pathology
62
Q

High pitched loud sounds

A

High amplitude and frequency sounds waves

Head and Neck (15 decks)

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