Anatomy And Histology Of The Ear Flashcards

1
Q

What does the external ear consist of?

A

Auricle to the tympanic membrane

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2
Q

What are the functions of the external ear?

A

Catches sound waves and directs them to EAM

EAM transmits sound waves to tympanic membrane

Spot to check an indiv. Temp.

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3
Q

What is the gold standard for checking an individual’s temperature and what is secondary to ti?

A

Rectal; external ear

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4
Q

What does the middle ear consist of?

A

Tympanic membrane to oval window

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5
Q

What are the functions of the middle ear?

A

Take sound waves from ext. and turn them into physical movement

Pressure equalization by pharyngotympanic tube

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6
Q

How do sound waves move in the middle ear?

A

Ext ear to physical movement; moving tympanic membrane to malleus to incus to stapes which then pushes on oval window

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7
Q

What changes the pressure of the middle ear?

A

Volume of the middle ear

Tympanic membrane can bulge out
Tensor tympani contracts o relaxes
Fluids go in and out

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8
Q

What does the inner ear consist of?

A

Oval window to internal acoustic meatus

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9
Q

What is the function of the inner ear?

A

Balance

Takes external sound waves and transforms them into usable info for the brain

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10
Q

What are the efferent and afferent nerve fibers during the cough reflex?

A

Efferent: vagus n. And phrenic n.

Afferent: glossopharyngeal n.

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11
Q

what innervated the superior portion of the EAM?

A

CN 7

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12
Q

What innervates the posterior portion of the EAM?

A

Great auricular n. (C3, 4)

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13
Q

What innervates the anterior portion of the EAM?

A

CN V3- Auriculotemporal n.

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14
Q

What innervates the inferior portion of the EAM?

A

CN X (Arnold N.)

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15
Q

How long is the canal leading to the tympanic membrane?

How is it shaped?

A

2-3 cm

Lateral 1/3 = s-shaped

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16
Q

Where and what are the glands of the ear?

A

Ceremonious glands = make wax
Sebaceous glands

In Integument

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17
Q

What comprises the outer 2/3s of the EAM?

A

Soft connective tissue and cartilage

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18
Q

What comprises the inner 1/3 of EAM?

What is the CT of this portion? Why is this clinically relevant?

A

Skin and bone

**Only place in the body where skin, periosteum and bone exist directly on top of each other

NO CT = bleeds easily

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19
Q

What bone is the middle ear located in?

A

Petrous portion of temporal bone

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20
Q

What are the two parts to the middle ear?

A

Tympanic cavity proper (aka mesotympanum)

Epitympanic recess

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21
Q

What are the boundaries of the middle ear?

A

Roof: tegmental wall

floor: jugular wall

Lateral wall: membranous wall

Medial wall: labyrinthine wall

Posterior wall: mastoid

Anterior wall: carotid wall

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22
Q

What are the 3 special features we can see in the middle ear?

A

Lateral semicircular canal
Facial n.
Labyrinth wall

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23
Q

What innervates the helix and depression of the external ear?

A

Facial N.

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24
Q

What innervates the lobule of the external ear and right behind the lobule?

A

Lesser occiptal n.

Greater auricular n.

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25
Q

What innervates the skin of the face anterior to the external ear?

A

Auriculotemporal (V3)

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26
Q

What innervates the concha of the external ear?

A

Vagus n. And Glossopharyngeal n.

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27
Q

What innervates the mastoid process and back of ear lobe?

A

Facial n.

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28
Q

What is the tympanic membrane?

A

Semi-transparent membrane ~1 cm in diameter

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29
Q

Histologically, what is the outer layer and what is the inner layer?

A

Outer: stratified squamous epithelium

Inner: simple cuboidal epithelium

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30
Q

What is the umbo?

A

Concavity in the tympanic membrane, creating a cone shaped projection oriented toward the EAM

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31
Q

What is the function of the tympanic membrane?

A

Moves with sound and transmits it to the ossicles

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32
Q

What is the external innervation of the tympanic membrane?

A

Auriculotemporal -V3

Also CN 6, 10

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33
Q

What is the internal innervation of the tympanic membrane?

A

CN V3

CN 10, 9

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34
Q

What are the auditory ossicles?

A

Malleus, incus, stapes

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35
Q

What is the function of the ossicles?

A

They bridge the tympanic membrane w/ the oval window of the cochlea

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36
Q

What is the short process of the incus connected to?

A

Posterior wall

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37
Q

What does the base of the stapes vibrate?

A

The oval window

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38
Q

What is the O, I, A and N of the Tensor Tympani M. ?

A

O: pharyngotympanic tube, greater sphenoid wing, petrous part of temporal bone

I: handle of malleolus

N: CN V3

A: pulls on handle of malleolus to tense membrane and reduce amplitude

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39
Q

What is the O, I, A and N of the Stapedius M.?

A

O: within pyramidal eminence

I: stapes

N: CN 7

A: pulls stapes posteriorly, tightening annular L attaching it to the oval window; reduces oscillatory tangle and prevents excess movement of stapes thereby dampening loud sounds

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40
Q

What is the blood supply to the external ear?

A

Posterior auricular a.
Superficial temporal a.

Anterior auricular As.

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41
Q

Where is the Pharyngotympanic tube?

A

In the middle ear connecting the tympanic cavity with the nasopharynx

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42
Q

What makes up the distal 2/3 of the Pharyngotympanic tube?

Proximal 1/3?

A

2/3: Boney
1/3 : Cartilage

(Distal 2/3 EAM- cartilage)
(Proximal 1/3 EAM - boney)

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43
Q

What is the function of the pharyngotympanic tube?

What sensation do we often associate with the PT Tube?

A

Equalize pressure

Ear popping sensation

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44
Q

What are the muscles that expand the PT Tube?

A

Levator Veli M.

Tensor Veli Palatini.

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45
Q

How does Levator Veli palatini interact with the PT Tube?

A

Contracts longitudinally which pushes against one wall of the PT Tube

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46
Q

How does the Tensor Veli Palatini M. Interact with the PT Tube?

A

Pulls on other wall of PT Tube

levator pushes the other

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47
Q

What is the bony labyrinth?

What is it lined with?

A

Cavity within the petrous region of the temporal bone

Lined with endosteum

48
Q

What separates the bony labyrinth front he membranous labyrinth?

A

Perilymph

49
Q

What i the membranous labyrinth?

What is it enclosed with?

A

Small sacs and tubes within the bony labyrinth

Enclosed with epithelium, making a continuous space

50
Q

What are the two sections of the membranous labyrinth?

A

Cochlear duct

Utricle, saccule, semicircular ducts

51
Q

Which labyrinth contains sensory cells?

A

membranous labyrinth

52
Q

What fills the membranous labyrinth?

A

Endolymph

53
Q

Differentiate where ducts vs. canals are.

A

Ducts: membranous labyrinth

Canals: bony labyrinths

54
Q

How do sound waves move thru the cochlea?

A

Scalia vestibule —> Scalia Media —> Scalia Tympani

55
Q

What fluid fills the Scalia media, tympani and vestibule?

A

Vestibule: perilymph

Media: Endolymph

Tympani: Perilymph

56
Q

What is the cochlear canal?

A

Spiral space within bone containing the cochlear duct

57
Q

What does the cochlear duct do?

A

Divides the cochlear canal into 3 paral soft tissue lined compartments

Scalia vestibuli, media, tympani

58
Q

What is the Stria Vascularis/

A

Lateral wall of Scalia media

Source of endolymph

59
Q

What is the scandal vestibuli next to?

A

By stapes at the oval window

Thus allows its perilymph to move

60
Q

What is the Scalia tympani connected to?

A

Round window

61
Q

Where is the organ of corti?

A

On the floor of scala media resting on basilar membrane

62
Q

What is the outer spiral lamina?

A

Inner spiraling bony shelf serving as a support for tectorial membrane and spiral ganglia

Between scala vestibuli and scala tympani

63
Q

How does sound move thru the cochlea?

A

Stapes —> oval window —>
fluid pressure wave in perilymph of scala vestibuli
—> distortion of vestibular membrane
—> pressure wave in Endolymph of scala media
—> basilar membrane distorting stereocilia of hair cells in tectorial membrane
—> pressure wave in perilymph of scala tympani
—> exits via round window

64
Q

What is the organ of corti composed of?

A

Hair cells
Inner and outer phalangeal cells (support for hair cells)

Pillar cells (support b/w b.m. And tympanic lip)

65
Q

How many rows of outer and inner hair cells are there in the organ of corti?

A

Outer rows: 3

Inner rows: 1

66
Q

Where are the hair cell stereocilia?

A

Embedding in overlying tectorial membrane extending from spiral lamina

67
Q

What happens when the basilar membrane is vibrated with sound?

A

Causes deflection of stereocilia attached to tectorial membrane opening K+ channels in hair cells

68
Q

How many semicircular canals are there?
what are they filled with?
What do they connect to?

A

3
Endolymph

Connected to utricle

69
Q

What are at the ends of the canals of the semicircular canals?

A

Ampulla with gelatinous like cap called a copula

70
Q

Where are hair cells attached to?

A

Innervated hair cells with stereocilia are attached to the cupulla

71
Q

What displaces the cupulla?

A

By fluid motion within the canal

72
Q

What do semicircular canals sense?

A

Sensors of roatational velocity

73
Q

What are the axes of the 3 canals of the semicircular canal?

A

Anterior: sagittal plane

Horizontal: transverse plane

Posterior: coronal plane

74
Q

What does the vestibular system of the inner ear contain?

A

Saccule and utricle

75
Q

What is a macula? Where is it found?

Function?

A

Found in both saccule and utricle

Comprised of cluster of hair cells with stereocilia w/ overlying gelatinous material called otolithic membrane

Sensor for gravity and linear acceleration

76
Q

Where is the otolithic membrane and what is it covered with?

A

Overlies macula’s cluster of hair cells with stereocilia

Covered with calcium carbonate/protein crystals called otoconia

77
Q

What does the Utricle sense?

How does the head tilt?

A

Linear acceleration

Head tilts horizontally

“U trip forward”

78
Q

What does the Saccule sense?

How does the head move?

A

Linear acceleration

Head tilts in vertical plane

“Suck up”

79
Q

Are there otoliths in the semicircular ducts?

A

No

Rather thick gel moves the hair cells

80
Q

What do semicircular canals have at their ampullae?

A

Hair cells

81
Q

Where are otoliths found?

A

In utricle and saccule

82
Q

What does the surface of the hair cells contain?

A

Rows of stereocilia called sensory hairs that increase in height in a particular direction

83
Q

What is the one true cilia in the vestibular system called?

Where is it located?

A

Kinocilium

Located behind tallest stereocilia

84
Q

What kind of channels are within the stereocilia?

A

Mechanoelectric gated ion channels that open or close K channels depending on how they are deflected

85
Q

Innervation by efferent nerves modulate what?

A

Sensitivity (hot and cold)

86
Q

where does the afferent nerve terminal go?

A

Brain

87
Q

How do you treat ototoxicity effects?

A

Antibiotics

88
Q

Where is the perilymphatic space located?

A

Between bony and membranous labyrinth?

89
Q

What is the composition of perilymph ?

A

Similar to CSF

Low k and proteins, high Ca, Na, H

90
Q

How does the perilymph drain?

A

Via perilymphatic duct (cochlear aqueduct) into subarachnoid space

91
Q

Where does perilymphatic originate from?

A

Periosteum

92
Q

Where is endolymphatic space?

A

Within membranous labyrinth

93
Q

What is the composition of endolymph?

A

High K, low Na

94
Q

Where does endolymph originate from?

A

Stria vascularis

95
Q

How does endolymph drain?

A

Via endolymphatic duct into venous sinuses of dura mater

96
Q

Where is the corticolymphatic space?

A

Within organ of corti

97
Q

How does damage to tympanic membrane occur?

How do you treat ruptured ear drum?

A

Fluid or barotrauma influence middle ear pressure

External trauma

Most heal on own; can treat with Abs

98
Q

What antibiotic should you not treat a ruptured ear drum with? Why?

A

Gentamicin

Bc it has risk of damaging hair cells

99
Q

What is mastoiditis?

Where can it spread?

How do you treat?

A

Infection of mastoid cells

Spread into cranial fossa via petrosquamous cranial suture

Treat w/ Abs

100
Q

What is otitis media?

Presents with?

If left untreated what occurs?

A

Ear ache with possible fluid or pus in middle ear due to inflammation or infection

Tympanic membrane - red and bulged
Fluid may be visible thru membrane

Impaired hearing and scarring of auditory ossicles

101
Q

What is the number one reason for hospital visits?

A

Otitis media

102
Q

What is Meniere’s syndrome?

A

Affects vestibular system- patients experience dizziness, vertigo, high pitched rushing or roaring sound (tinitis) w/ fluctuating hearing loss

103
Q

What is Meniere’s syndrome associated with?

How do you treat?

A

Increased endolymph volume leading to abnormal signaling in membranous labyrinth

Medication; severe cases require surgical ablation

104
Q

What is viral labyrinth it is?

A

Similar symptoms to Meniere’s (dizziness, vertigo, tinnitus, hearing loss)

But resolve within a week

105
Q

What is Conductive hearing loss?

A

Effects outer and middle ear

Fluid build up in middle ear due to otitis, excessive wax or otoscleosis

106
Q

What is sensorineural hearing loss?

A

Reduction in sound level and/or fidelity

Due to damage in inner ear or auditory n.

Age related and noise induced

(Can affect hearing at different frequencies and intensities)

107
Q

What is central hearing loss?

A

Problem in CNS

108
Q

What is the most common cause of hearing loss?

A

Aging

1 of 3 people age 65-74 has some level of hearing loss

109
Q

What are illnesses that can contribute to hearing loss?

A

Heart disease
High BP
Diabetes

110
Q

What are some medications that can impair hearing or balance? What are these called?

A

NSAIDS and lots of others

“Ototoxic”

111
Q

What are the two kinds of deafness that can be caused by genetics?

A

Syndrome deafness

Nonsyndromic deafness

112
Q

what can happen if you neglect an ear infection for too long?

A

Hearing loss

113
Q

What can excessive drinking or tobacco use cause in terms of hearing?

A

Damage to auditory cortex, affecting the way the brain processes sound

High levels of alcohol create a toxic environment which damage the delicate hair cells in the cochlear

114
Q

What is a common external ear pathology seen from wrestling?

How does this manifest?

A

Cauliflower ear

Auricle is made of elastic cartilage which is supplied by perichondrium
If injured, perichondrium will initiate chondrogenesis and cause new cartilage growth

115
Q

Why do 8/10 children suffer form otitis media before 10 years of age?

A

Angle of the Pharyngotympanic tube is more shallow in children

Allows for less drainage and pressure equalization of the inner ear

Heightens risk of infection and can cause pain or ear ache

116
Q

Patient is experiencing tensor tympani myoclonus(over active tensor tympani m.) and is therefore experienced muffled sounds.

What assoc. condition would you expec them to have?

A

Severe facial pain

Tensor tympani innerv. By CN V

Damage to CN V = trigeminal neuralgia

117
Q

A young child has ruptured the tympanic membrane with a pipe cleaner and has disrupted the middle ear?

What are you most concerned about in regard to the patient prognosis?

A

Loss of taste due to damage to Chorda tympani via facial n.

Damage is likely and irreparable