Head And Neck Session 6 Flashcards

1
Q

In which part of the temporal bone are the cochlear and vestibular organs located?

A

Petrous part (Otic canal)

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2
Q

What provides venous drainage of the inner ear?

A

Labyrinthine vein into the sigmoid or inferior petrosal sinuses

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3
Q

What provides arterial supply to the bony labyrinth of the inner ear?

A

Anterior tympanic branch of the maxillary artery, petrosal branch of MMA and stylomastoid branch of the posterior auricular artery

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4
Q

What provides arterial supply to the membranous labyrinth of the inner ear?

A

Labyrinthine artery, a branch of the inferior cerebellar artery that divides into one cochlear branch and 2 vestibular branches

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5
Q

What are the components of the inner ear?

A

Cochlear and vestibular organs

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6
Q

What is the membranous labyrinth?

A

Series of communicating sacs and ducts that contain endolymph

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7
Q

What fluid is endolymph similar to?

A

ICF

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8
Q

Describe the structure of the utricles.

A

Contains 5 openings of semicircular ducts and communicates with the saccule via the utriculosaccular duct

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9
Q

Where is the macula of the utricle found?

A

In the floor, parallel to the base of the cranium

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10
Q

What covers the surface of the macula of the utricle and saccule?

A

Sensory epithelium with hair cells

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11
Q

What innervates the macula of the utricle and saccule?

A

Vestibular branch of CNVIII

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12
Q

What do hair cells of the macula of utricle and saccule and hair cells of the crest in the semicircular ducts stimulate?

A

Primary sensory neurons in the vestibular ganglion of the IAM

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13
Q

What makes the saccule continuous with the cochlear duct?

A

Ductus reuniens

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14
Q

Where is the macula of saccule located?

A

Vertically on medial wall

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15
Q

What is the function of the ampullary crest in the semicircular ducts?

A

Sense movement of endolymph

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16
Q

How is the cochlear duct secured in the inner ear?

A

Spiral ligament and osseous spiral lamina of modiolus

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17
Q

What is the spiral ligament?

A

Spiral thickening of the periosteal lining of the cochlear canal

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18
Q

What are the two canals formed by the triangular shape of the cochlear duct?

A

Scala vestibuli and scala tympani

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19
Q

Describe the passage of excess endolymph from the utricle to its storage reservoir.

A

Capillaries in membranous labyrinth –> utricle –> endolymphatic duct –> vestibular aqueduct –> endolymphatic sac

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20
Q

Where is the endolymphatic sac located?

A

Under dura mater on posterior petrous part of the temporal bone

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21
Q

What is Ménière’s disease?

A

Vertigo, low pitched tinnitus and hearing loss due to excess of endolymph causing progressive distension of ducts in inner ear

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22
Q

What forms the lateral wall of the cochlear duct?

A

Spiral ligament

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23
Q

What forms the roof of the cochlear duct?

A

Reissener’s membrane (vestibular membrane) between the cochlear duct and scala vestibuli

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24
Q

What forms the floor of the cochlear duct?

A

Basilar membrane

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25
Q

Where is the spiral organ of Corti (receptor of auditory stimuli) located?

A

In basilar membrane overlaid by gelatinous tectorial membrane

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26
Q

Describe the passage of a wave of hydraulic pressure through the inner ear.

A

Scala vestibuli –> helicotrema –> scala tympani –> secondary tympanic membrane –> tympanic cavity –> deformation of cochlear duct –> disrupted hair cells

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27
Q

What is the internal acoustic meatus?

A

~1 cm long canal in petrous part of temporal bone, opening in the posteromedial part of the bone in line with the EAM

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28
Q

What closes the IAM laterally?

A

Thin, perforated plate of bone

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29
Q

What enters the IAM via its lateral end?

A

CNVII, CNVIII and BV

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30
Q

What happens to CNVIII at the lateral end of the IAM?

A

Divides into cochlear and vestibular branches

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31
Q

Which fluid is found in the bony labyrinth of the middle ear?

A

Perilymph

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32
Q

Which fluid is similar to perilymph?

A

ECF

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33
Q

What is the bony labyrinth of the inner ear?

A

Fluid-filled space surrounded by Otic capsules

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34
Q

How does the bony labyrinth hold the membranous labyrinth?

A

Delicate filaments (like arachnoid mater) and spiral ligament

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35
Q

Describe the structure of the cochlea.

A

Starts at vestibule, makes 2.5 turns around the bony mediolus core to form and anterolateral cone shape

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36
Q

What is found at the base of the modiolus?

A

BV and branches of the cochlear nerve

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37
Q

What type of bone is the modiolus made up of?

A

Spongy

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38
Q

What does the cochlea have that is closed by the secondary tympanic membrane?

A

Round window

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39
Q

What is the vestibule of the inner ear?

A

Small oval chamber containing utricle, saccule and vestibular labyrinth

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40
Q

How is the vestibule of the inner ear continuous with the posterior cranial fossa?

A

Via vestibular aqueduct

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41
Q

How does the vestibule of the inner ear open posterolateral to the IAM in the posterior petrous part of the temporal bone?

A

Via vestibular aqueduct

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42
Q

What does the vestibule of the inner ear transmit?

A

Endolymphatic duct and 2 small BV

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43
Q

Describe the arrangement of the semicircular canals.

A

Anterior, posterior and lateral lie posterosuperior to the vestibule and at right angles to each other with bony swellings (ampulla) at one end

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44
Q

Why are there only 5 openings into the vestibule of the inner ear when there are three semicircular canals?

A

Anterior and posterior canals have one common limb

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45
Q

What are lodged within the semicircular canals to facilitate balance?

A

Semicircular ducts

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46
Q

What are the components of the middle ear?

A

Ossicles, muscles, eustaschian tube, mastoid air cells and CNVII

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47
Q

What happens in cholesteatoma?

A

Persistent -ve pressure causes formation of retraction pockets where dead cells accumulate and form a necrotic cell mass (cholesteatoma) that releases lyric enzymes that erode surrounding tissues

48
Q

How does the tympanic cavity connect anteromedially to the nasopharynx?

A

Via pharyngotympanic tube

49
Q

How does the tympanic cavity connect with the mastoid air cells?

A

Through mastoid antrum

50
Q

What lines the tympanic cavity?

A

Mucous membrane that is continuous with the lining of the pharyngotympanic tube, mastoid cells and mastoid antrum

51
Q

What is the function of tensor tympani?

A

To reduce the amplitude of sound waves

52
Q

What gives innervation to tensor tympani?

A

CNV3

53
Q

Which part of stapes does stapedius attach to?

A

Neck

54
Q

Which part of stapes hits the oval window?

A

Base

55
Q

What is the function of stapedius?

A

Reduce oscillatory range to prevent excessive movement

56
Q

What gives innervation to stapedius?

A

CNVII

57
Q

What do you suspect has happened if you find O/E a child is missing the crease on the back of their ear?

A

Acute suppuration with back pressure into the tympanic cavity causing pus to accumulate in the mastoid air cells (mastoiditis)

58
Q

What forms the roof of the tympanic cavity?

A

Tegmen tympani below the dura mater of the middle cranial fossa

59
Q

What forms the posterior wall of the tympanic cavity?

A

Aditus to mastoid antrum

60
Q

What forms the medial wall of the tympanic cavity?

A

Initial part of cochlear plus oval and round windows

61
Q

What forms the floor of the tympanic cavity?

A

Layer of bone between cavity and superior bulb of IJV

62
Q

What forms the lateral wall of the tympanic cavity?

A

Tympanic membrane

63
Q

Why can damage to the lateral wall of the tympanic cavity result in loss of taste in the anterior 2/3 of tongue?

A

Chorda tympani is in close proximity so may be damaged

64
Q

Which important structure has a groove running close to the posterior wall of the tympanic cavity?

A

Facial nerve

65
Q

What forms the anterior wall of the tympanic cavity?

A

Superiorly the opening of the pharyngotympanic tube and canal for tensor tympani

66
Q

What is tegmen tympani?

A

Thin plate of bone separating middle cranial fossa and mastoid antrum

67
Q

Where is the mastoid antrum located?

A

Mastoid process of temporal bone

68
Q

How do mastoid air cells communicate with the antrum?

A

Via aditus

69
Q

What is the function of the mastoid air cells?

A

Act as a buffer system by releasing air into the tympanic cavity in low pressure

70
Q

Where are the mastoid air cells located in relation to the epitympanic recess?

A

Posterior to

71
Q

What are the consequence of pneumococcus/Haemophilus/strep infection in acute otitis media?

A

Inflammation causes a bulging eardrum leading to perforation, CNVII palsy, mastoiditis, meningitis. Can cause secondary prolonged negative pressure and thick effusions to form behind the ear drum leading to conductive hearing loss

72
Q

Describe the position of the pharyngotympanic tube.

A

From tympanic cavity posterior to inferior nasal meatus in nasopharynx

73
Q

How does the pharyngotympanic tube differ in children compared to adults?

A

Smaller, shorter and narrower in children

74
Q

Which portion of the eustaschian tube is bony?

A

Posterolateral 1/3

75
Q

What is the function of the pharyngotympanic tube?

A

Equalise pressure in middle ear by allowing air in and out of the tympanic cavity

76
Q

What happens if there is dysfunction of the equalisation of pressure by the pharyngotympanic tube?

A

Negative pressure in middle ear cavity leading to retraction of the eardrum

77
Q

Which muscles open the pharyngotympanic tube?

A

Levator veli palatini longitudinally and tensor veli palatini pulling opposite wall

78
Q

Why do your ears ‘pop’ when yawning or swallowing?

A

Muscles opening eustaschian tube are associated with the soft palate

79
Q

What gives arterial supply to the pharyngotympanic tubes?

A

Ascending pharyngeal artery from the ECA, MMA and artery of pterygoid canal

80
Q

Where do the veins of the pharyngotympanic tubes empty?

A

Pterygoid venous plexus

81
Q

What gives innervation to the pharyngotympanic tubes?

A

CNIX via the tympanic plexus and pterygopalatine ganglion

82
Q

Where does lymph from the pharyngotympanic tubes drain?

A

Deep cervical nodes

83
Q

Describe the structure of the auditory ossicles.

A

Exceptionally dense bone covered in tympanic cavity mucous membrane but no periosteum

84
Q

Describe the position of the malleus.

A

Head attaches to tympanic membrane and lies in epitympanic recess. Neck lies on pars flacidda. Handle in tympanic membrane with tip at umbo

85
Q

In which direction does tensor tympani pull malleus?

A

Medially

86
Q

Describe the position of the incus.

A

Large body in epitympanic recess parallel to the handle of malleus. Lenticular process articulates medially with stapes. Short limb is connected by a ligament to the posterior wall of the tympanic cavity

87
Q

What is the advantage of the base of stapes being smaller than the tympanic membrane?

A

Decreases amplitude of vibratory force

88
Q

What are the components of the external ear?

A

Auricle (pinna), external acoustic meatus (ear canal) and tympanic membrane

89
Q

How should the auricle be manipulated to examine the ear in adults compared to children?

A

Up, out and back for adults. Down and back for children

90
Q

What is the auricle?

A

Irregularly shaped plate of elastic cartilage covered by thin skin to capture and transmit sound to the EAM

91
Q

What gives arterial supply to the auricle?

A

Mainly posterior auricular and superficial temporal

92
Q

What gives venous drainage to the auricle?

A

Occipital veins

93
Q

What gives innervation to the auricle?

A

Cranial aspect, helix, anti helix and lobule = greater auricular nerve. Skin anterior to EAM = auriculotemporal nerve (CNV3)

94
Q

Where doe lymph drain to from the auricle of the ear?

A

Laterosuperior position –> superficial parotid lymph nodes. Cranial surface of superior half –> mastoid and deep cervical. Everything else –> superficial cervical

95
Q

What is the EAM?

A

Space between tympanic part of temporal bone and tympanic membrane (~2-3 cm in adults)

96
Q

Compare the structure of the lateral 1/3 and medial 2/3s of the EAM.

A

Lateral 1/3 = S-shaped and cartilaginous, lined with auricular skin. Medial 2/3s = bony with thin tympanic membrane skin

97
Q

What forms cerumen in the cartilaginous portion of the EAM?

A

Ceruminous and sebaceous glands

98
Q

What is the tympanic membrane?

A

1 cm diameter, thin, oval, semitransparent membrane oriented at 45 degrees to vertical

99
Q

How does the internal and external components of the tympanic membrane compare?

A

Thin skin externally and mucous membrane internally

100
Q

Why is infection risk increased further in tympanic membrane perforation when using detergents in the shower?

A

Water tension is lost

101
Q

What provides innervation to the tympanic membrane?

A

External surface = auriculotemporal and auricular branch of vagus. Internal surface = glossopharyngeal

102
Q

How are the collagen fibres arranged in the pars flacidda of the tympanic membrane?

A

Randomly

103
Q

How are the fibres of collagen arranged in the pars tensa of the tympanic membrane?

A

Radially

104
Q

What can be used on the tympanic membrane to orientate it?

A

Umbo points to bum. Cone of light points to toes

105
Q

Why does a patient with lobular/conceal remnant microtia/anotia have some hearing?

A

Neural portion develops separately

106
Q

What is a pre-auricular pit?

A

Squamous epithelium-lined tract near tragus

107
Q

What is a pre-auricular tag?

A

Epithelial mound/pedunculated skin near tragus

108
Q

What is cauliflower ear?

A

Consequence of pinna haematoma if it collapses

109
Q

What is otitis externa?

A

Where obstruction/absence of cerumen, trauma or altered EAM pH allow pseudomonas or staph colonisation

110
Q

What are the S/S of otitis externa?

A

Otalgia, hearing loss, tinnitus, discharge

111
Q

What is the Tx for otitis externa?

A

Analgesia, remove debris, Abx

112
Q

How does tympanic perforation arise?

A

Infection or trauma causes ischaemia

113
Q

What are the S/S of tympanic perforation?

A

Whistling in sneezing, reduced hearing

114
Q

What is pinna haematoma?

A

Trauma associated with the ear causes formation of a haematoma between cartilage and perichondrium leading to AVN of the cartilage

115
Q

What is the Tx for pinna haematoma?

A

Aspirate blood and stitch to prevent recurrence