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Neuro Endocrine > Anatomy and histology of the ear > Flashcards

Anatomy and histology of the ear Flashcards

1
Q

in an otoscope view what does the sensory for the: Anterior portion

A

CN V3, Auriculotemporal Nerve

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2
Q

in an otoscope view what does the sensory for the: posterior portion

A

C3 Great auricular nerve

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3
Q

in an otoscope view what does the sensory for the: superior portion

A

CN VII

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4
Q

in an otoscope view what does the sensory for the: inferior portion

A

CN X Arnold nerve

can cause the arnold cough reflex by touching this

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5
Q

In the cough reflex what is the efferent nerve and what is the afferent nerve

A

efferent: Vagus and phrenic nerve
afferent: vagus Nerve

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6
Q

what produces wax in the external auditory ear canal (external acoustic meatus)

A

ceruminous glands

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7
Q

How is the External acoustic meatus broken down

A

outer 2/3 soft connective tissue and cartilage

inner 1/3 is skin on bone

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

no connective tissue

therefore bleeds easily

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8
Q

what is the tympanic membrane made up

A

semitransparent membrane

outside layer lined with stratified squamous epithelium

inside layer lined with simple cuboidal epithelium

has concavity

moves with sound and transmits to ossicles

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9
Q

Parts of the tympanic membrane

A 
Handle of malleus
Umbo
Pars flaccida
anterior and posterior malleolar fold
cone of light
annulus
Pars tensa
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10
Q

what quadrant is the cone of light found in

A

2nd quadrant where the innervation is done by Vagus Nerve

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11
Q

What are the walls of the tympanic cavity

A 
roof (superior): Tegmental wall
floor (inferior): jugular wall
Laterally: membranous wall
Medially: Labyrinthine wall
Posteriorly: mastoid wall
anterior: carotid wall
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12
Q

what are the two parts of the tympanic cavity

A

Tympanic cavity proper

Epitympanic recess

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13
Q

What are the three ossicles in the tympanic cavity and how are they attached

A

Malleus which is attached to the tympanic membrane
Incus in the middle
stapes that attaches to the oval window

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14
Q

What nerves travel through the tympanic cavity

A 
Tympanic nerve (CN IX)
Tympanic plexus
Lesser petrosal nerve
Facial nerve (runs next to in the labyrinthine wall)
chorda tympani
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15
Q

what makes up the pharyngotympanic tube and what is its function

A

Connects the tympanic cavity (middle ear) with the nasopharynx

distal 2/3 boney
proximal 1/3 catilage

functions to equalize the pressures
-creates that ear popping sensation

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16
Q

What muscles expand the pharyngotympanic tube

A

Levator veli palatine: contracts longitudinally which pushes against one wall

TEnsor veli palatine: pulls on the other wall

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17
Q

how much does the ossicles amplify the force on the tympanic membrane

A

10x

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18
Q

Action and innervation of the tensor tympani muscle

A

Pulls on handle of the malleolus to tense membrane and reduce amplitude

inn: CN V

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19
Q

Action and innervation for the stapedius muscle

A

Pulls stapes posteriorly tightening annular ligament attaching it to the window

reduces oscillatory range and prevents excessive movement of stapes

inn: CN VII

20
Q

What does it mean if the tympanic membrane is tight

A

Need more energy to make vibration (reduces amplitude)

21
Q

What is the bony labyrinth

A

This is the cavity within the petrous region of the temporal bone

it is lined with endosteum and is seperated from the membranous labyrinth by perilymph

is considered the canals

22
Q

what is the membranous labyrinth and its two functions

A

made of small sacs and tubes within bony labyrinth

forms a continuous space enclosed with epithelium

2 sections with two different jobs

  • cochlear duct
  • utricle, saccule, semicircular ducts

is considered the ducts

23
Q

what are the three soft tissue canals that make up the cochlear duct

A

scala media : middle compartment that contains endolymph
-borders vestibular membrane, tectorial membrane, basilar membrane and the stria vascularis (makes endolymph)

Scala vestibuli: contains perilymph
moved by stapes at the oval window and is continuous with the scala tympani

scala tympani: connected to the round
full of perilymph

24
Q

where is the organ of corti located

A

found on the floor of the scala media resting on the basilar membrane

25
Q

WHat does the outer spiral lamina do

A

inner spiraling bony shelf that serves to support the tectorial membrane and the spiral ganglia

26
Q

What is the organ of corti and how does it work

A

composed of haircells,
inner and outer phalangeal cells (support cessl)
and pillar cells (support cells)

one row of inner hair cells
3 rows of outer hair cells

when the basilar membrane vibrates with sound it causes the stereocila attached to the tectorial membrane to move opening or closing K+ channels

27
Q

What is the function of the external ear

A

catches sound waves and directs them to the external auditory meatus and then to the tympanic membrane

can also check an individuals temperature here

28
Q

What is the function of the middle ear

A

THe middle ear takes sound waves and turns it into physical movement

also is important in changing the volume of the ear by tensing or relaxing the tympanic membrane

also important in equalizing the pressure in the ear and nasal cavity

29
Q

What is the inner ears function

A

The inner ear is responsible for balance

also is important for taking external sound waves and transforming them into usable information fro the brain

30
Q

The path of the sound wave when it enters the cochlea

A

1) stapes moves the oval window causing fluid pressure wave formation in the perilymph of the scala vestibuli
2) wave distorts the vestibular membrane causing pressure wave within the endolymph of the scala media
3) this displaces the basilar membrane and distorts sterocila of hair cells
4) pressure in the perilymph is transfered to scala tympani and exits via the round window

31
Q

How do the semicircular canals and ampulla work

A

there are three canals in three different axis
-Ant-sagital
-post- Coronal
transverse- horizontal

endolymph is filled and it is connected to the utricle

at the end of the canals they have aampulla which has a gelatinous like cap called a cupulla

there are innervated hair cells with sterocilla that are attached to the cupulla so that if the cupulla moves it moves the haircells

serve as sensors for rotational velocity

32
Q

What is found in a utricle and a saccue

A

Vestibule contains a saccule and utricle

each contain a macula
-this is comprised of a cluster of hair cells with stereocilia with overlying gelatinous membrane called the otolithic membrane

the otolithic membrane is then covered with calcium carbonate/protein crystals called otoconia

33
Q

What is the purpose of the utricle

A

linear acceleration and head tilts in horizontal plane

-U trip forward

34
Q

What is the purpose of the saccule

A

Linear acceleration and the head tilts in vertical plane

suck up

35
Q

what happens if the stereocilia move towards the kinocilium

A

there is a depolarization because of the opening of the K+ channels

36
Q

What happens if the stereocilia move away from the kinocilium

A

there is hyperpolarization because of the closing of the K + channels

37
Q

What drug causes ototoxicity to these hair cells

A

some types of antibiotics

38
Q

Charachteristics of Perilymph

A

Composition similar to CSD, High in Na+ and low in K+ and protein

drains via the perilymphatic duct into the subarachnoid space

originates from periosteum

between Bony and membranous labytinths

39
Q

Characteristics of endolymph

A

High in K+ and protein but low in Na+

originates from stria vascularis

Drains via endolymphatic duct into venous sinuses

found within membranous labyrinth

and in the corticolymphatic space

40
Q

What happens if the perichondrium is sheared off the elastic cartilage in the external ear

A

get hematoma and necrotic cartilage

then you gen cartilage growth via chondrogenesis

presents as cauliflower ear

41
Q

Damage to tympanic membrane

A

often due to:
medial ear pressure because of fluid or barotrauma

most heal but need follow up perhaps with antibiotics

42
Q

Mastoiditis

A

Infection of mastoid cells

can spread into cranial fossa via petrosquamous cranial suture

treated with antibiotics

43
Q

Otitis media

A

Ear infection

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

tympanic membrane appears red and bulged

fluid maybe visible through membrane

untreated can impair hearing and scarring of auditory ossicles

44
Q

Menieres syndrome

A

experience dizziness, vertigo, high pitched rushing or roaring sound (tinnitus) and fluctuating hearing loss

associate with increase endolymph volume leading to abnormal signaling

treat with medication

or surgical ablation

similar symptoms to viral labyrinths but are resolved within a week

45
Q

hearing loss

A

lots of causes

conductive hearing loss in outer or inner ear:
fluid build up, otits, excessive wax, otoscleosis

sensorineural hearing loss: reduction in sound level and/ or fidelity due to damage to inner ear or auditory nerve
affects hearing at different frequencies and intensities
-age related
-noise induced

Central hearing loss: problem in CNS

Neuro Endocrine (20 decks)

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