Clinical Anatomy of the Ear Flashcards

1
Q

what nerves are contained within the temporal bone?

A
CN 7 (facial)
CN 8 (vestibulocochlear)
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2
Q

what is the pterion?

A

an H shaped suture (thinnest part of the skull)

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3
Q

what bones join to create the pterion?

A

temporal
parietal
sphenoid
frontal

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4
Q

what happens if the pterion is damaged?

A

the middle meningeal artery can perforate causing an epidural haematoma

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5
Q

where is the petrous part of the temporal bone?

A

between sphenoid and occipital bone at the base of the skull

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6
Q

what foramen is located on the petrous part of the temporal bone?

A

stylomastoid froamen

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7
Q

why is the stylomastoid foramen called such?

A

its located between the styloid and mastoid processes

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8
Q

what bones make up the anterior cranial fossa?

A

frontal
ethmoid
sphenoid

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9
Q

what bones make up the middle cranial fossa?

A

sphenoid

temporal

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10
Q

what bones make up the posterior cranial fossa?

A

temporal

occipital

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11
Q

what part of the cranial fossa does the petrous part of the cranial fossa make up?

A

most of middle

some of posterior

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12
Q

name the nerves that exit the cranial fossa at the superior orbital fissure?

A
CNs:
2
3
4
5
6
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13
Q

what nerve exits through the foramen rotundum?

A

CNV2

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14
Q

what nerve exits through the foramen ovale?

A

CNV3

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15
Q

through which foramen does the internal carotid go through to get to the brain?

A

intracranial opening of carotid canal

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16
Q

what nerves go through the internal acoustic meatus?

A

acoustic = hearing so CN 7 + 8

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17
Q

what structures go through the jugular foramen?

A

jugular vein
CN9
CN10
CN11

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18
Q

what structure does CNXII go through?

A

hypoglossal canal

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19
Q

another word for the tympanic membrane?

A

eardrum

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20
Q

where does the external ear start and end

A

auricle to tympanic membrane

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21
Q

main function of the external ear?

A

collect and convey sound waves to tympanic membrane

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22
Q

where does the middle ear start and end?

A

tympanic membrane to oval window

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23
Q

the eustachian tube is in what compartment of the ear?

A

middle

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24
Q

what does the middle ear do?

A

amplifies and conducts sound waves to the internal ear

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25
Q

where does the internal ear start and end?

A

oval window to internal acoustic meatus

26
Q

what does the internal ear do?

A

converts special sensory information to fluid waves then APs then conducts them to brain

27
Q

what cartilage covers the external ear?

A

elastic

28
Q

what proportion of the ear canal is bony/cartilaginous?

A

1/3 cartilage

2/3 bony

29
Q

name the structures that make earwax

A

ceruminous glands

30
Q

what sensory nerve supplies the helix and outer portion of the external ear?

A

C2, 3 spinal nerves

31
Q

what sensory nerve supplies most of the tympanic membrane?

A

CNV3

32
Q

what parts of the ear does the vagus nerve supply?

A

inferior part of external acoustic meatus

small part of tympanic membrane

33
Q

where does lymph from the ears drain to?

A

deep cervical lymph nodes in carotid sheath

34
Q

is the EAM short and straight in adults or children?

A

children

35
Q

how should you pull the auricle to examine a child?

A

posteroinferiorly

36
Q

sensory nerve supply to the external TM?

A

CNV3

37
Q

sensory nerve supply to the internal TM?

A

CNIX

38
Q

what does the eustachian tube connect?

A

TM to lateral wall of nasopharynx

39
Q

why can tonsillitis mimic earache?

A

both supplied by CNIX

eustachian tube connects the two regions

40
Q

where is the epitympanic recess located in the middle ear cavity?

A

superior to the TM

41
Q

name the auditory ossicles of the middle ear from the 1st bone to connect to the TM

A

malleus
incus
stapes

42
Q

how do the auditory ossicles help to transmit sound?

A

when TM moves with sound waves it causes each ossicle to vibrate 1 by 1 until the stapes hits the oval window

43
Q

where is the tympanic cavity in the middle ear?

A

posterior to the TM

44
Q

mastoiditis can be caused by infection where in the ear?

A

middle ear

45
Q

smallest skeletal muscle in the body?

A

stapedius

46
Q

what 2 foraminae are connected by the facial canal

A

IAM

stylomastoid foramen

47
Q

what nerve does the chorda tympani come off of?

A

facial nerve cn7

48
Q

nerve functions of the facial nerve?

A

special sensory
sensory
motor
parasympathetic

49
Q

what does the chorda tympani supply?

A

taste buds of anterior 2/3rds of tongue

submandibular and sublingual salivary glands (parasymp)

50
Q

what does the stapedius muscle do?

A

reduces stapes movement to prevent internal ear from excessive noise

51
Q

how does the chorda tympani get to the tongue?

A

“hitches a ride” with CNV3

52
Q

where do the muscles of facial expression originate and insert?

A

originate on bone

insert on superficial fascia

53
Q

name the 2 parts of the vestibulocochlear nerve and their functions

A

vestibular nerve- balance

cochlear nerve- hearing

54
Q

where is the otic capsule of the inner ear located?

A

temporal bone

55
Q

what part of the otic capsule contrains perilymph?

A

bony labyrinth

56
Q

where are the sacs and ducts of the otic capsule located?

A

within the membranous labyrinth

57
Q

what is the “snail-like” part of the otic capsule called?

A

cochlea

58
Q

what are the 3 ring shaped parts of the otic capsule called?

A

semicircular canal

59
Q

what parts of the otic capsule control
1. hearing
2. balance
and why

A
  1. cochlea (connect to cochlear nerve)

2. semicircular canals (connects to vestibular nerve)

60
Q

what happens once the vibrations of the ossicles have hit the oval window?

A

creates pressure waves in perilymph
hair cells in cochlea move
APs released to cochlear nerve
pressure waves become vibrations and are dampened

61
Q

where do the vestibular and cochlear nerves connect?

A

IAM

62
Q

what happens from a pathology at the IAM?

A

loss of facial epression, taste, dry mouth, reduced auricle sensation- cn7
ipsilateral loss of hearing and balance- cn 8