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Head and neck > 7 - Ear > Flashcards

7 - Ear Flashcards

1
Q

Which bone of the skull contains the parts of the ear?

A

Petrous part of temporal bone

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2
Q

What comprises the external ear?

A

Pinna
External auditory meatus
Lateral surface of tympanic membrane

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3
Q

What is the function of the external ear?

A

Collects, transmits and focuses soundwaves onto tympanic membrane

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4
Q

What causes abnormalities of the pinna?

A

Ramsey-Hunt syndrome: Shingles of facial nerve, sensory ganglia affected
Trauma: Cauliflower ear, cartilage destroyed

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5
Q

Describe the process that leads to cauliflower ear

A

Pinna haemotoma - accumulation of blood between cartilage and perichondrium, which deprives the cartilage of its blood supply - necrosis
Fibrosis and asymmetrical cartilage development - cauliflower ear

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6
Q

How is a pinna haematoma treated?

A

Prompt drainage
Prevent reaccumulation of blood
Re-apposition of cartilage and perichondrium

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7
Q

What needs to be done when examining tympanic membrane?

A

Pull ear up and back to straighten sigmoid shape of ear

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8
Q

Describe the structure of the external acoustic meatus

A

Cartilaginous outer 1/3 - full of hair and wax to prevent objects entering deeper and gets shed epithelial cells out of ear
Inner 2/3 - bony, no hairs

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9
Q

How long is the external acoustic meatus?

A

2.5 cm

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10
Q

What is otitis externa?

A

Inflammation of external acoustic meatus, can’t see tympanic membrane.
Caused by eczema or swimmers ear

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11
Q

What causes perforation of the tympanic membrane?

A

Pus accumulation on other side of membrane, increasing pressure
Middle ear pushing against membrane - bulging secondary to otitis media

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12
Q

What is the function of the middle ear?

A

Amplify vibration from tympanic membrane to cochlea via oval window - air to fluid medium

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13
Q

What comprises the middle ear?

A

Ossicles - malleus, incus and stapes
Pharyngotympanic tube
Oval window

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14
Q

How are the ossicles joined?

A

Synovial joints

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15
Q

What is the acoustic reflex?

A

Tensor tympani (V3) and stapedius (VII) muscles contract in response to excessive vibrations to prevent damage from loud noises

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16
Q

What is hyperacousis?

A

Acoustic reflex is lost due to loud noises

17
Q

What is otosclerosis?

A

Base of stapes and oval window become fused

No fluid moving in inner ear so vibrations not transmitted -deafness

18
Q

What is the function of the pharyngotympanic tube?

A

Equilibrate pressure of middle ear to atm pressure
Mucous membrane in middle ear continuously reabsorb air, causing negative pressure
Pharyngotypanic tube, via nasopharynx, allows drainage of air and mucus from middle ear

19
Q

Why are children more likely to develop a middle ear infection?

A

Pharyngotympanic tube shorter and more horizontal in children
Easier passage for infection from nasopharynx
Tube blocks easily, compromising drainage, increasing risk of middle ear infection

20
Q

What is otitis media with effusion/glue ear?

A

Build up of transudate and negative pressure in middle ear
Due to pharyngotympanic dysfunction
Tympanic membrane retracted and is straw coloured

21
Q

How is otitis media with effusion treated?

A

Most resolve spontaneously

Grommets to ventilate middle ear

22
Q

What is acute otitis media?

A

Acute middle ear infection, causes red bulging tympanic membrane

23
Q

What are the complications of acute otitis media?

A

Tympanic membrane perforation
Facial nerve/ chorda tympani damage as runs through middle ear cavity
Mastoiditis
Intracranial: Meningitis, sigmoid sinus thrombosis, brain abscess

24
Q

What is mastoiditis?

A

Mastoid swells up, turning ear foreward

Middle ear cavity communicates with mastoid antrum with mastoid air cells, route for infection

25
Q

What is cholesteatoma?

A

Sac/cyst of skin cells growing into middle ear, behind tympanic membrane
Secondary to chronic ear infections
Causes painless, smelly otorrhea (ear discharge)
Tympanic membrane retracted due to negative pressure caused by blockage of pharyngotympanic tube

26
Q

What is the function of the inner ear?

A

Cochlea converts vibration into electrical signals, interpreted as sound
Vestibular apparatus maintains sense of balance

27
Q

Describe how cochlea enables sound to be heard

A

Movements at oval window cause movement of the fluid in the cochlea
Fluid waves cause stereocilia cells to move within cochlear duct
Generates action potential in vestibulocochlear (VIII)

28
Q

If the cochlear is damaged, what kind of hearing loss develops?

A

Sensorineural hearing loss

29
Q

Describe the overall process of hearing

A

1 - Auricle and external auditory canal focus/funnel sound wave to tympanic membrane, which vibrates
2 - Vibration of the ossicles sets up movement in cochlear fluid
3 - Movement sensed by stereocilia in cochlear duct
4 - Movement of stereocilia trigger action potentials in vestibulocochlear (VIII)
5 - VIII sends signals to primary auditory cortex in temporal lobe

30
Q

What constitutes the vestibular apparatus?

A

Semicircular ducts
Saccule
Utricle

31
Q

What is the function of the vestibular apparatus?

A

To respond to position and rotation and maintain sense of balance

32
Q

What are the symptoms of vestibular apparatus disease?

A

Vertigo
Hearing loss
Tinatus
Nystagmus (involuntary eye movement)

33
Q

What disease affect the inner ear?

A

Meniere’s disease - fluid build up in labyrinth of inner ear
Benign paroxysmal positional vertigo - spinning feel when turning head, calcium carbonate moving round inner ear
Labyrinthitis - inflammation of inner ear, infection

34
Q

What causes conductive hearing loss?

A 
Pathology involving external or middle ear:
Wax
Otitis media
Glue ear 
Otosclerosis
35
Q

What causes sensorineural hearing loss?

A 
Pathology involving inner ear or vestibulocochlear (VIII) nerve 
Presbyacusis (age related hearing loss) 
Meniere's disease 
Acoustic neuroma 
Ototoxic meds

Head and neck (14 decks)

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