The External and Middle Ear Flashcards

1
Q

Innervation of the auricle?

A

Cutaneous innervation

-greater auricular, lesser occipital and branches of facial and vagus nerves

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2
Q

Why can cleaning your ears sometimes cause you to cough?

A

Can stimulate the auricular branch of the vagus nerve

Vagus nerve is responsible for the cough reflex.

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3
Q

Vasculature of the auricle?

A

Posterior auricular, superficial temporal, occipital arteries and veins

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4
Q

What is the external acoustic meatus?

A

Sigmoid shaped tube extending from the deep part of the concha to the tympanic membrane

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5
Q

What gives the external acoustic meatus structure?

A

Cartilage from the auricle

Bony support from the temporal bone

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6
Q

Innervation of the external acoustic meatus?

A

Sensory innervation

-branches of the mandibular and vagus nerve

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7
Q

Describe the direction that the external acoustic meatus travels

A

Initially superioanterior
Then superioposterior
Then inferioanterior

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8
Q

What are the two layers of the tympanic membrane?

A

Skin on the outside
Mucous membrane on the inside
Core of connective tissue

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9
Q

What is the tympanic membrane connected to?

A

Surrounding temporal bone by a fibrocartilaginous ring

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10
Q

How is the malleus attached to the tympanic membrane?

A

The handle of malleus attaches at the umbro

Continues superiorly and it has a lateral process of malleus at its highest point

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11
Q

What are the parts of the membrane moving away from the tympanic membrane called?

A

Anterior and posterior malleolar folds

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12
Q

What is an auricular haematoma?

A

When blood collects between cartilage and overlying perichondrium usually as a exult of trauma

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13
Q

What can an auricular haematoma lead to and how?

A

Accumulation of blood disrupts the vascular blood supply to the cartilage of the pinna so if not drained quickly, can get a cauliflower ear

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14
Q

What can perforate the tympanic membrane?

A

Trauma or infection
Otitis media causes pus and fluid to build up causing an increase in pressure so that is eventually ruptures
Membrane normally heals itself, but may require surgery

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15
Q

Function of the auricle?

A

Captures and transmits sound to the external acoustic meatus

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16
Q

Which bone does the middle ear lie within?

A

The temporal bone

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17
Q

Where does the middle ear extend from and to?

A

From the tympanic membrane to the lateral wall of the internal ear

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18
Q

Purpose of the middle ear?

A

Transmit vibrations from the tympanic membrane to the inner ear via three bones

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19
Q

Sections of the middle ear?

A

Tympanic cavity - medial to the tympanic membrane which contains the majority of bones of the middle ear
Epitympanic recess - superiorly, near mastoid air cells

20
Q

Borders of the middle ear?

A

Visualised as a rectangular box

Roof: thin bone from petrous part of temporal bone.

Floor: ‘jugular wall’. Thin layer of bone separates it from internal jugular

Lateral: tympanic membrane and epitympanic recess

Medial: lateral wall of inner ear

Anterior: thin bony plate with two openings for the auditory tube and tensor tympani muscle. Separates mid ear from internal carotid

Posterior: aka mastoid wall. A bony partition between the tympanic cavity and mastoid air cells. Hole in the partition superiorly allowing communication called the aditus to the mastoid antrum

21
Q

What does the roof separate the middle ear from?

A

Middle cranial fossa

22
Q

What makes a bulge in the medial wall of the inner ear?

A

Facial nerve

23
Q

Names of the auditory ossicles?

A

Malleus
Incus
Stapes

24
Q

What do they connect?

A

Tympanic membrane to the oval window of the internal ear

25
Q

Where does the head of the malleus lie?

A

Epitympanic recess where it articulates with the incus

26
Q

What does the incus consist of and what does it articulate with?

A

Body and two limbs
Body articulates with malleus
Short limb attaches to posterior wall
Long limb to the stapes

27
Q

Shape of the stapes? Articulations?

A

Stirrup shaped - head, two limbs and a base
Head with incus
Base to oval window

28
Q

What are the muscles called in the middle ear?

A

Tensor tympani and stapedius

29
Q

Function of the muscles of the middle ear?

A

Contract in response to loud noise, inhibiting vibrations of the bones
Reduces transmission of sound to the inner ear
Called the acoustic reflex

30
Q

Attachments of the muscles?

A

Tensor tympani: from auditory tube to handle of malleus, pulls it medially
Stapedius: attaches to stapes

31
Q

Innervation of the muscles?

A

Tensor tympani - branch of mandibular nerve

Stapedius - facial nerve

32
Q

Where are the mastoid air cells located? What are they?

A

Posterior to the epitympanic recess
Collection of air-filled spaces in the mastoid process of the temporal bone
Contained within a cavity called the mastoid antrum

33
Q

Function of the mastoid air cells?

A

Act as a buffer system - release air into the tympanic cavity when pressure is too low

34
Q

How do the mastoid air cells communicate with the middle ear?

A

Aditus to middle antrum

35
Q

What two things does the Eustachian tube connect?

A

Middle ear to the nasopharynx

36
Q

Function of the Eustachian tube?

A

Equalises pressure of middle ear to that of the external auditory meatus

37
Q

What is cholesteatoma?

A

Growth of stratified squamous epithelium in the middle ear

Can be congenital or acquired

38
Q

What problems can cholesteatoma cause?

A

Damage bones of middle ear due to increase pressure
Releases osteolytic enzymes
Patients present with hearing loss and sometimes facial nerve palsy

39
Q

How to treat cholesteatoma?

A

Surgery to remove it

40
Q

What is mastoiditis?

A

Otitis media can spread to the mastoid air cells, as its a good site for pathogenic replication

41
Q

Complications of mastoiditis?

A

Mastoid process gets infected and can spread to middle cranial fossa causing meningitis

42
Q

How is mastoiditis treated?

A

Pus is drained from air cells, careful of nearby facial nerve

43
Q

What is glue ear?

A

Otitis media with effusion

44
Q

How does otitis media with effusion arise?

A

Arises from persistent dysfunction of auditory tube
If tube is unable to equalise middle ear pressure (blockage, inflammation, genetic mutation), a negative pressure develops inside the middle ear which draws out transudate from the mucosa of the middle ear
Creates an environment suitable for pathogens to replicate and cause infection

45
Q

How does the ear drum appear in glue ear?

A

Inverted, fluid visible

46
Q

Why are children more prone to infection?

A

Eustachian tube is shorter and more horizontal