Clinical Anatomy of the Ear Flashcards

1
Q

what bone houses the mechanisms for hearing and balance?

A

temporal

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2
Q

what are the two parts of the external ear?

A

pinna

external acoustic meatus

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3
Q

what marks the medial end of the external acoustic meatus?

A

the tympanic membrane

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4
Q

what forms the pinna?

A

elastic cartilage attached to the temporal bone, encased in skin

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5
Q

which part of the EAM is formed by cartilage?

A

the lateral third

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6
Q

what is the EAM lined with?

A

skin continuous with the pinna, containing ceruminous glands

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7
Q

what do ceruminous glands produce?

A

earwax

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8
Q

what are the two parts of the temporal bone?

A

squamous

petrous

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9
Q

what supplies the sensory nerve supply to the inferior part of the EAM and tympanic membrane?

A

CN X

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10
Q

what supplies the sensory nerve supply to the superior parts of the EAM and most of the tympanic membrane?

A

CN V3 via the auriculotemporal nerve

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11
Q

what supplies the sensory nerve supply to the superior portion of the helix?

A

C2 and C3 spinal nerves via the lesser occipital nerves

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12
Q

what supplies the sensory nerve supply to the earlobe?

A

C2 and C3 spinal nerves via greater auricular nerve

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13
Q

what is used to examine the EAM and tympanic membrane?

A

an otoscope

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14
Q

what is the thin part of the tympanic membrane called?

A

pars flaccida

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15
Q

what is the most inwardly depressed part of the tympanic membrane called?

A

the umbo

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16
Q

what is the thick part of the tympanic membrane called?

A

pars tensa

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17
Q

where is the cone of light normally directed in otoscopy?

A

anteroinferiorly

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18
Q

what are the first bones to fully ossify during development?

A

the ossicles

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19
Q

what is the function of the ossicles?

A

convey vibrations of the tympanic membrane due to sound and conduct them to the inner ear

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20
Q

from lateral to medial, what are the ossicles?

A

malleus
incus
stapes

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21
Q

what forms the connections between the ossicles and what does this allow?

A

small synovial joints

smooth movements between the bones

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22
Q

how are the ossicles suspended in the tympanic cavity?

A

by small ligaments and mucosal folds

these carry small vessels and nerves that supply the ossicles

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23
Q

what are the two muscles found in the tympanic cavity?

A

tensor tympani

stapedius

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24
Q

where does tensor tympani insert?

A

malleus

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25
Q

what innervates tensor tympani?

A

CN V3

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26
Q

where does stapedius insert?

A

stapes

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27
Q

what innervates stapedius?

A

CN VII

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28
Q

where is the tympanic cavity located and what does it contain?

A

the petrous portion of the temporal bone

contains the apparatus for the middle ear

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29
Q

what are the two parts of the tympanic cavity?

A

tympanic cavity proper

epitympanic recess

30
Q

what nerve supplies the mucosa of the middle ear?

A

glossopharyngeal nerve

CN IX

31
Q

where is the epitympanic recess found?

A

superior to the tympanic membrane

32
Q

what is the opening in the posterior wall of the epitympanic recess called?

A

the mastoid aditus

opens into the mastoid air cells

33
Q

what is the roof of the tympanic cavity called?

A

tegmen tympani

34
Q

what separates the tympanic cavity from the middle cranial fossa?

A

roof of the tympanic cavity

35
Q

what vessel is closely related to the floor of the tympanic cavity?

A

the internal jugular vein

36
Q

what are the four key features of the medial wall of the tympanic cavity?

A

oval window
round window
promontory
facial canal

37
Q

what does the oval window do?

A

receives the footplate of the stapes

38
Q

what does the round window do?

A

dissipates forces from the cochlear

39
Q

what is the promontory?

A

the bump from the basal (first) turn of the cochlear

40
Q

what does the facial canal contain?

A

the facial nerve (CN VII)

41
Q

what is the connection between the middle ear and the nasopharynx called?

A

the eustachian tube

42
Q

where is the opening for the eustachian tube found in the nasopharynx?

A

posterior to the inferior nasal concha

43
Q

what forms the eustachian tube?

A

posterior third = bone

rest = cartilage

44
Q

what is the role of the eustachian tube?

A

equalise air pressure between the middle ear and the nasopharynx

45
Q

what is the torus tubarius?

A

a feature of the nasopharynx caused by the cartilaginous opening of the eustachian tube

46
Q

what is the mucosa of the nasal cavity continuous with and how?

A

the mucosa of the middle ear

via the eustachian tube

47
Q

where can pain from inflammation of the tonsils/pharynx be referred to?

A

the ear, causing otalgia

48
Q

where is the inner ear located?

A

deep within the petrous portion of the temporal bone

49
Q

what are the two main structures of the inner ear?

A

bony labyrinth

membranous labyrinth

50
Q

what is the bony labyrinth?

A

a fluid filled network in the otic capsule

51
Q

what is the membranous labyrinth?

A

a series of communicating ducts and sacs suspended in the bony labyrinth

52
Q

what parts of the inner ear are involved in hearing?

A

cochlear

53
Q

what parts of the inner ear are involved in balance?

A

semi-circular canals
utricle
saccule

54
Q

what are the three parts of the bony labyrinth?

A

cochlear
vestibule
semi-circular canals

55
Q

what is the cochlear?

A

a shell shaped spiral cavity encircling a bony core

contains the round window

56
Q

what is the bony core of the cochlear called?

A

the modiolus

57
Q

what is the vestibule and what does it contain?

A

a small oval shaped chamber containing the utricle and saccule

contains the oval window

58
Q

what are the vestibular organs?

A

utricle and saccule

59
Q

what are the semi-circular canals?

A

three bony canals that communicate with the vestibule

are oriented at right angles to each other

60
Q

what suspends the membranous labyrinth in the bony labyrinth?

A

spiral ligament

delicate filaments

61
Q

which two semi-circular canals have a shared stalk?

A

posterior and anterior ducts

62
Q

what are the three semi-circular ducts?

A

anterior
lateral
posterior

63
Q

what achieves conversion of mechanical to neural stimuli in the inner ear?

A

specialised mechanoreceptors called hair cells

64
Q

where are the hair cells within the vestibular apparatus located?

A

maculae of the utricle and saccule

ampullae of the semi-circular ducts

65
Q

how do the neural stimuli generated by hair cells reach the CNS?

A

via the vestibular nerve

a division of CN VIII

66
Q

where are the cell bodies for the neurons of the vestibular nerve located?

A

within the vestibular ganglion

67
Q

what are the three fluid filled channels that make up the cochlear?

A

scala vestibuli
scala tympani
cochlear duct/scala media

68
Q

what is the apex of the cochlear called and what ducts meet here?

A

helicotrema

scala vestibuli and tympani

69
Q

where are hair cells located in the cochlear apparatus?

A

the organ of corti

70
Q

how do neural stimuli travel from hair cells of the cochlea to the CNS?

A

the cochlear nerve

71
Q

where are the cell bodies of the cochlear nerve located?

A

the spiral ganglion