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Head and Neck > Anatomy and disorders of the ear > Flashcards

Anatomy and disorders of the ear Flashcards

1
Q

Anatomy of the external ear

A

Pinna/auricle - whole thing
Helix
Antihelix (anterior to helix)
Tragus (most anterior)
Lobule (ear piercing location)

External acoustic meatus
Lateral tympanic membrane

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2
Q

3 parts of ear

A

External
Middle
Inner

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3
Q

Symptoms/signs of ear disease

A

Otalgia (ear pain, but can be referred pain and not ear pathology)
Discharge (can be on pillows)
Hearing loss (conductive vs sensorineural)
Tinnitus (ringing)
Vertigo
Facial nerve palsy - facial nerve goes throigh petrous bone, close relationship to ear

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4
Q

Describe vertigo

A

Feeling of room spinning around you
Hallucination of movement

It is important to refine ‘dizziness’ when pts report to see if it is vertigo

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5
Q

What makes up external ear?

A

Pinna and external auditory (acoustic) meatus
(lateral part of tympanic membrane)

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6
Q

What is external ear lined with?

A

Skin - keratinised squamous epithelium

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7
Q

What makes up middle ear?

A

Air filled
Ossicles x3 - malleus, incus, stapes
Connected to nasopharynx via Eustachian (pharyngotympanic) tube

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8
Q

What lines middle ear?

A

Respiratory epithelium - pseudostratified columnar ciliated epithelium with goblet cells

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9
Q

What makes up inner ear?

A

Fluid-filled
Cochlea
Semi-circular canals - anterior, lateral and posterior

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10
Q

What nerve is connected to inner ear for hearing?

A

Vestibulocochlear nerve - CN VIII

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11
Q

What does tympanic membrane act as?

A

Barrier between external and middle ear
Lateral is external, medial is middle

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12
Q

Branches of nerves that carry general sensation from ear

A

Cervical spinal nerves (C2/C3)

Vagus

Trigeminal (auriculotemporal)

Glossopharyngeal (tympanic)

And Facial nerve (small contribution)

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13
Q

What can occur due to the large amount of nerves carring general sensation from ear?

A

Referred pain - brain perceives pain is coming from sensory area on skin instead of visceral (organ) pain as they are supplied by same branch of nerve

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14
Q

What nerve is responsible for special sense hearing and balance?

A

CN VIII - Vestibulocochlear

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15
Q

What does it mean if someone has otalgia with normal ear on examination?

A

Pathology elsewhere due to referred pain

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16
Q

Causes of non-otological otalgia

A

Temporomandibular joint - CN Vc (trigemincal madibular portion)

Diseases of oropharynx - CN IX (glossopharyngeal)

Diseases of larynx and pharynx eg cancers - CN IX and X (glossopharyngeal and vagus)

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17
Q

Function of the pinna, external auditory meatus and lateral tympanic membrane - the external ear

A

Collects, transmits and focuses soundwaves onto tympanic membrane

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18
Q

What materials make up the external ear?

A

Skin
Cartilage
Fatty tissue

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19
Q

Causes of pinna (auricle) abnormalities

A

Congenital - different shapes/positions
Inflammatory - Ramsay hunt syndrome (vesicles on ear and facial palsy)
Infective - Perichondritis
Traumatic - Pinna haematoma and cauliflower ears

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20
Q

What is perichondritis?

A

Infection of the connective tissue layer called the perichondrium which overlies the cartilage (similar concept to periosteum)

Causes painful, red and swollen ear
Abx needed

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21
Q

What is pinna haematoma?

A

Accumulation of blood between cartilage and perichondrium due to blunt trauma

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22
Q

Length of external acoustic meatus

A

2.5cm long - need to be carful with speculum

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23
Q

Where are pinna haematomas common?

A

Contact sports - eg rugby

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24
Q

What happens in pinna haematoma?

A

Subperichondrial haematoma deprives cartilage of blood supply (cartilage is avascular)
There is then pressure necrosis of cartilage tissue

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25
Q

Treatment for subperichondrial haematoma/pinna haematoma

A

Drainage
Prevent reaccumulation of blood by placing cotton roll either side of ear sandwhiching ear between

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26
Q

What happens if a pinna haematoma goes untreated?

A

Fibrosis of cartilage (as it has been starved of blood supply)
New asymmetrical cartilage development = cauliflower deformity (not reversible)

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27
Q

What happens in subperichondrial haematoma to layers?

A

Perichondrium is stripped off cartilage

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28
Q

Description of external acoustic meatus

A

Skin-lined cul de sac 2.5cm long
Lined with keratinising, stratified squamous epithelia (skin)
Outer is cartilaginous(1/3), inner is bony (2/3)
Sigmoid shape

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29
Q

What lines the cartilage part of the external acoustic meatus?

A

Hair, sebaceous and ceruminous glands acting as a barrier to foreign objects

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30
Q

What do ceruminous glands do?

A

Produce wax

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31
Q

What lines the bony part of external acoustic meatus?

A

NO glands or hair like the cartilage part

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32
Q

How to examine external acoustic meatus?

A

Pull auricle of ear out and up to straighten bony channel

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33
Q

How does the external acoustic meatus get clean?

A

Self cleaning:
Desquamation (skin cell removal) and skin migration occurs laterally off tympanic membrane and out of canal

AKA epithelial migration

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34
Q

Conditions that affect the external acoustic meatus

A

Wax/foreign bodies
Otitis externa

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35
Q

Normal tympanic membrane features

A

Pars flaccida (‘attic’, superior and loose part of membrane)
Incus
Umbo (central part of tympanic membrane)
Pars tensa (inferior and tense part of membrane)
Manubrium of malleus (long white section aka handle of malleus)
Cone of light (from otoscope)
Short process of malleus (edge of manubrium)

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36
Q

Rare complication of otitis externa

A

Malignant otitis externa - very rare but serious and potentially life threatening, infection of EAM and temporal bone

Immunocompromised inc diabetics more at risk

Psueodomonas aeruginosa causes usually

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37
Q

What is otitis externa?

A

Inflammation of the external auditory meatus caused by infection
Can cause pain, itchiness, discharge or even temporary hearing loss
Also known as swimmers ear - moist ears are ideal environment for bacteria to grow

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38
Q

Common abnormalities in tympanic membrane

A

White plaques - sclerosis indicating previous trauma

Bulging - secondary to bacterial acute otitis media (infection of middle ear)

Retracted (sucked in) and evidence of fluid in middle ear - otitis media with effusion

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39
Q

Reason for acute otitis media causing bulging

A

Pus and exudate accumulate in middle ear
Increased pressure in middle ear
Bulges laterally

40
Q

Reason for retracted tympanic membrane

A

Increased -ve pressure in middle ear sucking the pars flaccida in
Cause is NOT infection

41
Q

Normal tympanic membrane shape

A

Concave as you look at it
Points towards middle ear

Cone of light at 5pm for R and 7pm for left

42
Q

What is a cholesteatoma? Describe how it occurs

A

Usually formed secondary to eustachian tube dysfunction (= increased -ve pressure in middle ear)

-ve pressure pulls pars flaccida inwards forming sac/pocket
Stratified squamous epithelium and keratin get trapped (as cannot migrate laterally as normal)
This proliferates forming cholesteatoma

43
Q

Normal function of eustachian tube

A

Opens and closes intermittently to equilibrate pressure so that middle ear pressure matches atmospheric (as eustachian tube is connected to nasopharynx)

44
Q

Symptoms of cholesteatoma

A

Painless but often a smelly otorrhoea (ear discharge) +/- hearing loss

45
Q

Cholesteatoma if not treated?

A

Not malignant but slowly grows and expands

More serious consequence - Enzymatic bony destruction can occur which can lead to erosion of ossicles, mastoid/petrous bone or cochlea

46
Q

Description of the middle ear

A

Air filled cavity between tympanic membrane and inner ear containing ossicles

47
Q

How are ossicles connected?

A

Synovial joints

48
Q

Function of ossicles

A

Amplify and relay vibrations from the tympanic membrane to the oval window of the the cochlea (stapes hits oval window)

49
Q

What happens once stapes transmits vibrations to oval window?

A

Vibrations are converted to waves in fluid within cochlea

50
Q

Lateral to medial ossicles

A

Malleus
Incus
Stapes

51
Q

What is the acoustic reflex?

A

Ossicle movement is tampered by two muscles in the scenario of loud noise - stapedius and tensor tympani

52
Q

What is otosclerosis?

A

Ossicles fuse at articulations due to abnormal bone growth
Particularly between base plate of stapes and oval window
= sound vibrations not transmitted as effectively to cochlea

53
Q

Cause of otosclerosis

A

Genetic and environmental - not sure especially of cause (viral? hereditary?)
BUT it is one of the most common causes of hearing loss in young adults

54
Q

Why does the pharyngotympanic (eustachian) tube have to equilibrate the pressure of middle ear with atmospheric? What causes middle ear to be -ve pressure if this doesnt happen?

A

Mucous membranes in middle ear reabsorb air causing negative pressure
Tube opens and allows equilibration of pressure inside middle ear to atmospheric

Also allows for ventilation and drainage of mucus

55
Q

What is otitis media with effusion? AKA glue ear

A

Not actual infection but can predispose to it
Actually due to eustachian tube dysfunction
Negative pressure in ear draws fluid out of mucous membranes = fluid and pars flaccida sucked in

56
Q

Consequence of otitis media with effusion

A

Decreased motility of tympanic membrane and ossicles leading to decreased hearing ability

57
Q

Treatment for otitis media with effusion

A

May resolve spontaneously (2-3 months)
If impeded speech and language development or perists - grommets (tympanostomy tube)

58
Q

What does a grommet (tympanostomy tube) do?

A

Allows communication with middle ear and external acoustic meatus
Another communication with atmosphere allowing equilibration of pressures

59
Q

Sign of otitis media with effusion

A

Retracted tympanic membrane
Fluid line beneath or air bubbles (middle ear usually just filled with air and no fluid)

60
Q

Acute otitis media - what and who does it affect?

A

Acute middle ear infection
More common in infants/children than adults

61
Q

Signs and symptoms of acute otitis media

A

Otalgia - infant may pull/tug at ear
Non specific - eg temperature
Red +/- bulging tympanic membrane

62
Q

Cause of acute otitis media

A

Viral usually
Can be bacterial - streptococcus pneumoniae or haemophilus influenzae

63
Q

Why do children get acute otitis media and otitis media with effusion more than adults?

A

Eustachian (pharyngotympanic) tube is shorter and more horizontal than adults

= easier passage of infection from nasopharynx, the tube can also block more easily compromising drainage and equilibration of pressures

64
Q

What is present where nasopharynx and eustachian tube meet in infants?

A

Lots of lymphatic tissue - adenoids (pharyngeal) tonsils
These can also cause obstruction of eustachian tube

65
Q

Complications of acute otitis media

A

Tympanic membrane perforation (resolve on own)

Facial nerve involvement - close relationship to middle ear when in facial canal of petrous bone. Chorda tympani and n to stapedius go through middle ear cavity.

Mastoiditis

Intracranial complications - meningitis, sigmoid sinus thrombosis, brain abscess

66
Q

What causes mastoiditis?

A

Middle ear cavity communicates to mastoid air cells (cavities) via mastoid antrum

Middle ear infections can spread into mastoid bone via here

67
Q

Appearance of mastoiditis?

A

Redness around mastoid bone
May be swollen that it pushes ear forward

68
Q

How can sigmoid sinus thrombosis occur?

A

If invasion of infection erodes through petrous bone, sigmoid sinus is below middle ear and external auditory meatus
= thrombosis

69
Q

what traverses next to eustachian tube

A

Internal carotid artery

70
Q

What are the parts of the inner ear?

A

Vestibular apparatus
Cochlea

Both fluid filled - endolymph

71
Q

What is vestibular apparatus involved in?

A

Sense of position/balance

72
Q

What is cochlear involved in?

A

Special sense hearing

73
Q

What generates fluid movement in cochlea?

A

Footplate of stapes against oval window

74
Q

What generates fluid movement of endolymph in vestibular apparatus?

A

Position and rotation of head

75
Q

How is fluid movement converted into action potentials to travel via CN VIII vestibulocochlear?

A

By stereocilia (specialised hair cells) - these move as fluid moves and generate action potentials

76
Q

Inner ear pathology triad

A

Hearing loss - sensorineural
Tinnitus
Disturbances of balance and vertigo

77
Q

Where are stereocilia located?

A

Within inner ear - cochlear duct in the organ of corti

78
Q

Two windows present between cochlea and middle ear

A

Oval window - stapes vibrates against
Round window

79
Q

Summary of how we hear

A

Auricle and external acoustic meatus focus and funnels sound waves towards tympanic membrane

Vibration of ossicles - amplified and stapes vibrates at oval window causing movement in endolymph in cochlea

This movement is sensed by stereocilia in cochlea duct (organ of corti)

Movement of stereocilia in organ of corti = action potentials triggers in cochlear part of CN VIII

Primary auditory cortex in temporal lobe

80
Q

Where is endolymph?

A

Within vestibular apparatus and cochlear duct of cochlea

81
Q

What makes up the vestibular apparatus?

A

Semicircular ducts/canals (anterior, posterior lateral)
Saccule
Utricle

82
Q

What happens in teh vestibular apparatus?

A

Moving position or rotating head moves fluid within
This bends stereocilia
Generates AP to CNVIII to brain = perception of balance

83
Q

What do the sterrocilia in the utricle and saccule respond to?

A

Rotational acceleration and static pull of gravity

84
Q

What do the stereocilia in semicircular ducts respond to?

A

Rotational acceleration in 3 planes

85
Q

Conditions affecting cochlea

A

Presbycusis - Sensorineural hearing loss associated with old age, Bilateral and gradual

86
Q

Condtion affecting vestibular apparatus

A

Benign paroxysmal positional vertigo
Vertigo only
Short lived episodes - seconds triggered by movement of head

87
Q

Test and treatment for BPPV

A

Test - Dix-Hallpike manoeuvre
Treat - Epley manoeuvre

88
Q

Cause of BPPV

A

Crystals within vestibular apparatus dislodge and move fluid
This is perceived by brain as head movement as stereocilia is moved

89
Q

Conditions affecting cochlea and VA

A

Meniere’s
Acute labyrinthitis
Acute vestibular neuronitis

90
Q

What is meniere’s disease?

A

Vertigo, hearing loss and tinnitus (typically unilateral)
Aural fullness, nausea and vomitting (from vertigo)
Symptoms longer than BPPV - 30mins-24 hrs
Recovery between episodes but hearing may deteriorate over time

91
Q

Cause of menieres

A

Problems with endolymph - too much production or too little drainage

92
Q

Acute labyrinthitis vs acute vestibular neuronitis

A

Both involve history of upper resp tract infection
AL - involvement of all inner ear structures so associated with hearing loss, tinnitus, vomitting and vertigo

AVN - just VA so usually no hearing disturbances or tinnitus. Sudden onset vomiting and severe vertigo (for days)

93
Q

Examination for hearing loss presentation

A

Inspection and palpation of external ear

Otoscopy

Gross hearing assessment - whisper word and pt repeat back

Tuning fork test - Weber’s and Rinne’s (external/middle vs inner ear loss, good for unilateral loss)

94
Q

Conductive hearing loss caused by…

A

Pathology involving external or middle ear eg wax, acute otitis media, otitis media with effusion, otosclerosis

95
Q

Sensorineural hearing loss caused by///

A

Pathology involving inner ear (COCHLEA) or CN VIII eg presbycusis, noise-related, menieres, ototoxic medications (furosemide, vancomycin or gentamicin), acoustic neuroma

VA apparatus not involved as no hearing function

96
Q

What is acoustic neuroma?

A

Tumour on cochlea or CN VIII
Impairing function causing unilateral hearing loss

97
Q

Most common pathogen causing otitis externa

A

Pseudomonas aeruginosa and staphylococcus aureus

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