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AHNNS > 11. Functional Anatomy And Disorders Of The Ear > Flashcards

11. Functional Anatomy And Disorders Of The Ear Flashcards

1
Q

Within which bone of the skull are the parts of the ear found?

A

Petrous part of the temporal bone.

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2
Q

What are the 3 parts of the ear?

A

External, middle and inner ear.

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3
Q

What is the function of the external ear?

A

Collects, transmits and focuses sound waves onto the tympanic membrane.

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4
Q

What 3 structures comprise the external ear?

A

Pinna.
External auditory meatus.
Lateral surface of tympanic membrane.

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5
Q

What does the pinna comprise of?

A

Cartilage, skin and fatty tissue.

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6
Q

What is Ramsey-Hunt syndrome?

A

Shingles (reactivation of the varicella zoster virus) causing shingles of the pinna. Also causes a facial nerve palsy (weakness of one side of the face).

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7
Q

What happens in a pinna haematoma?

A

Accumulation of blood between the cartilage and pericardium of the pinnacle, secondary to blunt injury.

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8
Q

How should a pinna haemotoma be treated?

A

Prompt drainage, take measures to prevent re-accumulation and re-apposition of the two layers is necessary.

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9
Q

What deformity is can an untreated or poorly treated pinna haematoma cause?

A

Cauliflower deformity of the ear due to fibrosis and new asymmetrical cartilage development.

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10
Q

Why does the ear need to be pulled up and back to straighten when examining?

A

The external acoustic meatus is sigmoid shape.

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11
Q

In which portion of the external acoustic meatus are there hairs and is wax produced?

A

Cartilaginous (outer 1/3).

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12
Q

What is the purpose of the arrangement of hairs and production of wax in the external acoustic meatus?

A

Prevent objects entering the deep ear canal.

Aid in desquamation and skin migration out of the canal.

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13
Q

How long is the external acoustic meatus?

A

2.5 cm.

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14
Q

What is otitis externa?

A

Inflammation of the external acoustic meatus eg eczema and swimmers (water in ears, bacteria breed).

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15
Q

What 2 things can cause perforation of the tympanic membrane?

A

Perforation by an object.

Increase in pressure due to infection eg build up of pus and discharge.

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16
Q

What can be seen at the tympanic membrane secondary to otitis media (middle ear infection)?

A

Bulging.

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17
Q

What is the middle ear comprised of?

A

The ossicles and an air filled cavity.

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18
Q

What is the function of the middle ear?

A

Is an air filled cavity between the tympanic membrane and the inner ear, which contains 3 ossicles which amplify vibration from the tympanic membrane to the cochlea via the oval window.

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19
Q

What are the 3 ossicles?

A

Malleus, incus, stapes.

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20
Q

What is the acoustic reflex?

A

Tensor tympani and stapedius muscles contract in response to a potentially excessive vibration due to loud noise, decreasing the transmission of vibrational energy to the cochlea, where it is converted into electrical impulses to be processed by the brain.

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21
Q

What is otosclerosis?

A

Fusion of the ossicles at articulations, in particular between the base plate of the stapes and oval window. This means sound vibrations cannot be transmitted, causing deafness.

22
Q

What is the function of the pharyngotympanic tube (eustachian tube)?

A

Equilibrates pressure of the middle ear (mucous membrane of the middle ear continuously reabsorbs air in the middle ear, causing negative pressure).
Allows for ventilation of and drainage of mucus from the middle ear.

23
Q

What causes otitis media with effusion (glue ear) and how does this affect hearing?

A

Build up of fluid and negative pressure in the middle ear due to Eustachian tube dysfunction. (Is not an infection).
Decreases mobility of the tympanic membrane and ossicles affecting hearing.

24
Q

What is the treatment for otitis media with effusion (glue ear)?

A

Most resolve spontaneously in 2-3 months, it some may persist, and so require grommets to ventilate the middle ear.

25
Q

What can predispose the middle ear to infection?

A

East ACh Ian tube dysfunction.

26
Q

How does the tympanic membrane look in otitis media with effusion (glue ear)?

A

Retracted and tympanic membrane looks straw coloured.

27
Q

What causes acute otitis media?

A

An acute middle ear infection.

28
Q

Acute otitis media is more common in infants and children rather than in adults. Why is this anatomically?

A

The pharyngotympanic tube is shorter and more horizontal in infants, to it is easier to the passage of infection from the nasopharynx to the middle ear. And the tube can block more easily, compromising ventilation and drainage of the middle ear, increasing risk of middle ear infection.

29
Q

What symptoms does acute otitis media cause?

A

Otalgia (ear pain which may lead to infants pulling or tugging at the ear).
Other non-specific symptoms eg temperature.
Red, bulging tympanic membrane and loss of normal landmarks.

30
Q

Name 3 complication of acute otitis media.

A

Tympanic membrane perforation.
Facial nerve involvement.
Rarer but potentially life-threatening complications:
Mastoiditis.
Intracranial complications (meningitis, sigmoid sinus thrombosis, brain abscess).

31
Q

What is mastoiditis?

A

Infection spreading from the middle ear cavity into the mastoid air cells of the mastoid bone.

32
Q

How does the middle ear cavity communicate with the mastoid air cells?

A

Via the mastoid antrum

33
Q

What 2 signs are seen in mastoiditis?

A

Swollen area behind ear.

Ear pushed forward.

34
Q

What nerve may be involved in pathology involving the middle ear and why?

A

Facial nerve, as it and one of its branches, the chora tympani, runs through the middle ear cavity.

35
Q

What is a cholesteatoma?

A

Abnormal skin growth (sac or cyst of skin cells) growing into the middle ear, behind the tympanic membrane.

36
Q

What signs/symptoms does a cholesteatoma cause?

A

Painless, smell otorrhea (ear discharge), with or without hearing loss.
Can potentially cause more serious neurological complications.

37
Q

What is a cholesteatoma usually secondary to?

A

Chronic Eustachian tube dysfunction or chronic/recurring ear infections.

38
Q

What does the inner ear comprise of?

A

The vestibular apparatus and cochlea.

39
Q

What is the function of the inner ear?

A

The cochlear converts vibration into an electrical signal (action potential) which is perceived as sound. The vestibular apparatus is involved in maintaining our sense of position and balance.

40
Q

How does the cochlear generate action potentials in the CN VIII?

A

Movements at the oval window sets up movements of the fluid in the cochlear. The waves of fluid cause movement of special sensory cells within the cochlear duct which generate action potentials in the CN VIII.

41
Q

What is the name of the special sensory cells int eh cochlea duct?

A

Stereocilia.

42
Q

Where does the CN VIII carry signals from the cochlear to?

A

The primary auditory cortex.

43
Q

What structures is the vestibular apparatus made of? And what are they?

A

Semicircular ducts, the saccule and utricle.

Are a fluid filled series of channels and sacs that respond to position and rotation and maintain our sense of balance.

44
Q

Name 2 diseases of the inner ear caused by pathology involving the vestibular apparatus.

A

Ménière’s disease.
Benign paroxysmal positional vertigo.
Labrynthitis.

45
Q

Give 3 symptoms that can occur as a result of a disease involving the vestibular apparatus

A

Vertigo.
Hearing loss and tinnitus.
Nystagmus.

46
Q

Where is there pathology in conductive hearing loss and give 3 causes of conductive hearing loss.

A

External and middle ear.

Wax, otitis media, glue ear, otosclerosis.

47
Q

Where is the pathology in sensorineural hearing loss and give 3 causes of sensorineural hearing loss.

A

Inner ear structures or CN VIII.

Presbyacusis, Ménière’s disease, acoustic neuroma, ototoxic medication.

48
Q

How do you perform a Rinne’s test?

A

Ring tuning form over mastoid process and then in front of ear. Which is louder, bone or air conduction?

49
Q

How do you perform a Weber’s test?

A

Ring tuning fork and place in centre on top of head. Same or louder in one ear?

50
Q

In sensorineural hearing loss, when will a Rinne’s and Weber’s test be louder?

A

Rinne’s - louder in air than bone.

Weber’s - louder in normal ear.

51
Q

In conductive hearing loss, when will a Rinne’s and Weber’s test be louder?

A

Rinne’s - louder in bone than air.

Weber’ - louder in affected ear.

AHNNS (17 decks)

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