Ear (stephens) Flashcards

1
Q

3 divisions of the ear

A

external ear
middle ear
internal ear

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2
Q

external ear structures and function

A

auricle (pinna) and external auditory meatus

-collect and conduct sound, and protect eardrum

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3
Q

blood supply to the auricle

A

superficial temporal and posterior auricular artery

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4
Q

sound conduction

A

sound vibrations are conveyed to the inner ear via vibrations of ossicles and fenestra vestibuli

  • air conduction and fenestra cochlea
  • bone conduction through petrous temporal bone
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5
Q

hearing receptors in inner ear are protected from trauma by 3 mechanisms

A

1) sudden, loud sounds cause footplate of stapes to rock side to side rather than depress directly into fenestra vestibuli
2) continuous loud sound cause contraction of stapedius and tensor tympani muscles and attenuation of vibrations
3) cochlear pathway in CNS is capable of filtering, focusing and attenuating sound

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6
Q

auricular hematoma

A

trauma to pinna may cause hemorrhaging in subcutaneous tissue
-if not evacuated and bandaged scar tissue may grossly deform auricle into cauliflower ear
(superficial temporal and posterior auricular arteries)

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7
Q

external auditory meatus shape and length

A

2.5 cm, curves slightly anteriorly as it ends blindly at tympanic membrane

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8
Q

how to examine external auditory meatus during otoscopic examine

A

pull upward, outward and backward on auricle

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9
Q

tympanic membrane location and size

A

located at medial end of external auditory meatus

  • 1 cm in diameter
  • tilted forward, lateral and downward in canal
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10
Q

3 layers of tympanic membrane

A

outer epidermis innervated by GSA fibers from trigeminal and vaugs nerves

middle fibrous layer forms pars tensa
-absence of this in antero-superior quadrant forms pars flaccida

inner mucous membrnae innervated by GVA fibers of IX near tympanic plexus

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11
Q

where does the chorda tympani nerve course through in tympanic membrane

A

through anterior and posteior mallear folds

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12
Q

what is superior-anterior to tympanic membrnae

A

auditory tube

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13
Q

what is superior-posterior to the tympanic membrane

A

long process of incus, stapes, fenestra vestibuli

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14
Q

what is inferio-posterior to tympanic membrane

-clinical sig

A

fenestra cochlea

-electronic ray for cochlear implants here

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15
Q

what is inferio-anterior to tympanic membrane

A

carotid canal

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16
Q

malleus articulates with ___ and what nerve crosses its neck

A

articulates with incus

-chorda tympani crosses its neck

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17
Q

incus articulates with what

A

between malleus and stapes

  • body articulates with malleus
  • long crus articulates with head of stapes
18
Q

stapes articulation

A

head articulates with long crus of incus

-anterior and posgterior crura connect the head to footplate which articulates with fenestra vestibuli

19
Q

tensor tympani muscle location and insertion

A

located in semicanal above auditory tube

-tendon inserts on handle of malleus

20
Q

innervation of tensor tympani muscle and function

A

mandibular nerve V3

-tightens tympanic membrane and attenuates its vibrations

21
Q

stapedius muscle location and insertion

A

located in pyramid on posterior wall of middle ear cavity

-tendon inserts on neck of stapes

22
Q

innervation of stapedius muscle

and function

A

facial nerve

-pulls stapes out of oval window (protection)

23
Q

facial nerve pathway leaving brainstem

A

facial nerve travels laterally in the internal auditory meatus then enters facial canal

  • geniculate ganglion located just above here at this is where the nerve turns shaprly posteriorly to form external genu
  • after 1.0 cm the nerve courses downward and sends a branch to the stapedius muscle and exits the stylomastoid foramen
24
Q

internal auditory meatus

location cochlear, facial and vestibular nerve

A

facial nerve
cochlear nerve——————–vestibular nerve

Anterior posterior

25
Q

what are the receptors of the inner ear

A
  • cochlear receptors for hearing
  • receptors in semicircular ducts: detect angular acceleration
  • receptors in sacculus and utricle: detect linear acceleration
26
Q

inner ear receptors are innervaed by what and what function

A

cochlear division of VIII: innervates organ of corti (auditory info)

vestibular division innervates semicircular ducts (static and dynamic postion-sense info for equilibrium)

27
Q

what artery innervates inner ear, and arteriorsclerosis of it may cause what

A

labyrinthine artery, branch of AICA

-vertigo, nausea

28
Q

what does the osseous labyrinth consists of

A

semicircular canals, vestibule, cochlea

29
Q

osseous labyrinth encloses the ___ space filled with ___

A

perilymphatic space filled with perilymph

30
Q

3 pairs of semicircular canals

A

anterior and posterior are oriented at a 90 degree angle in vertical plane
lateral canal tilted 30 degrees upward from horizontal plane

31
Q

vestibule houses what

A

utricle (elliptical cavity)

saccule (spherical cavity)

32
Q

cochlea bony core is called ____ and what nerve passes through

A

modiolus, cohclear nerve passes through

33
Q

what projects from the modiolus

A

spiral lamina, cochlear duct is attached to spiral lamina

34
Q

semicircular ducts are dilated at one end = ___

which contains a receptor organ called what and what is this function

A

ampulla, crista ampullaris

-detects angular acceleration

35
Q

utricle and saccule are located where and connect to form what

A

in vestibule, form endolymphatic duct

36
Q

the utricle communicates with what and contains what receptor organ and fnct of this

A

all 5 semicirular ducts, contains macula utricle, detects linear accelaration

37
Q

the saccule receptor organ and fnct

A

macula saccule, detects low frequency vibrations

38
Q

cochlear duct

A

continues with saccule contains organ of corti (spiral organ)
receptors for hearing

39
Q

tiny blood vessels in area of spiral ligament called ____ supply organ of corti

A

stria vascularis

40
Q

prolonged exposure to excessive amounts of noise and or music may lead to destruction of what

A

organ of corti