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ANAT + PHYS (9610) > UNIT 7: External Ear and Middle Ear > Flashcards

UNIT 7: External Ear and Middle Ear Flashcards

1
Q

3 transduction/transmission parts of hearing

A

transduction of sound from acoustical energy to mechanical energy

transduction of mechanical energy into electrochemical energy

transmission and interpretation of electrochemically produced siganl

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2
Q

the ear is a structure that houses the….

A

vestibulocochlear organs for senses of equilibrium and hearing

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3
Q

3 divisions of ear

A

external ear
middle ear
inner ear

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4
Q

main function of the external/outer ear

A

gathering and conducting sound to tympanic membrane

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5
Q

external outer ear includes

A

auricle and concha
external auditory meatus

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6
Q

lower animals have an advantage w their external ear

A

can control position of auricles to capture sound using auricular muscles (innervated by CN VII)

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7
Q

Most visible part of hearing apparatus

A

auricle/pinna

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8
Q

auricle/pinna are made of…. and attached to the ….

A

flexible, thin elastic cartilage core = auricular cartilage

attached to skull around opening of external auditory meatus by muscles and ligaments

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9
Q

cartilaginous core of pinna is continuous w ______

A

cartilaginous portion of EA

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10
Q

structures of auricle/pinna are constant despite…

A

genetic variation in shape and size

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11
Q

auricle/pinna reaches adult size by

A

9-12 years

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12
Q

external auditory meatus is ____ in length, from ____ to _____, roughly ____ shaped in path

A

2.5 cm
concha to tympanic membrane
S shaped

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13
Q

external auditory meatus’s lateral 1/3 is _____ and medial 2/3 is ____

A

cartilaginous
bony

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14
Q

bony portion of EAM diameter is slightly ____ then cartilaginous portion, _____ end is sloped, EAM has its own _____ characteristics

A

less then cartilaginous portion

medial

resonant

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15
Q

EAM’s bony portion has a narrow concentric groove called

A

tympanic sulcus

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16
Q

tympanic membrane is a ____ and ____ membrane, ___mm in diameter - separates the ___ from _____

A

thin and oval
10 mm
external ear from tympanic cavity

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17
Q

differences in lengths of roof and floor of EAM put the TM in an _______

A

oblique position

angle formed bw TM and floor of the EAM is about 55’

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18
Q

under the light the tympanic membrane has a

A

glistening pearly grey appearance

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19
Q

bc of the TM’s concavity and oblique orientation the anterior/inferior quadrant…

A

glows brightly and is called the cone of light

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20
Q

TM is _____, w its center point called the ____

A

concave
umbo

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21
Q

TM is semitransparent - the outline of the _____

A

handle of malleus (attached to medial surface) can be seen extending upwards and forwards

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22
Q

two regions of the TM are

A

pars flaccida and pars tensa

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23
Q

malleolar fold in the TM is

A

created by ligament attaching lateral process of malleus to TM

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24
Q

the TM is attached to the tympanic sulcus of the EAM by

A

a fibrous ring = annular ligament - aka a circular ring of CT …. annular meaning it runs all the way around

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25
Q

annular ligament has ____ CT in the region of the pars flaccida and ____ CT in region of the pars tensa

A

sparse CT
fibrous CT

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26
Q

TM is a trilaminar membrane, its 3 layers are

A

lateral surface = continuous w skin of EAM

middle layer = core of fibrous CT

inner (medial) layer = continuous w mucosa of TM

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27
Q

the skin covering the auricle and lining the ear canal and lateral surface of the TM is …. what is found in this skin?

A

closely attaches to underlying cartilage and bone

hair follicles, sebaceous and ceruminous glands - cerumen (ear wax) formed from glandular secretions entraps foreign particles, protecting the hearing apparatus

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28
Q

concha and pinna are innervated by

A

facial nerve VII
Auricular branch of vagus X
glossopharyngeal IX

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29
Q

EAM and external TM innervated by

A

facial nerve VII
auricular branch of vagus X
auriculotemporal branch of mandibular nerve (V3)

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30
Q

why is the ear innervated by so many CNs?

A

its important
rly wanna be able to feel foreign particles

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31
Q

otitis externa is …. caused by …

A

inflammation of the skin of the external ear

swelling is v painful - inc tension on the epithelium that is tightly bound to underlying cartilage or bone

bacterial infection following trauma or abrasion

viral infection, including herpes zoster

trauma - destruction cartilaginous infrastructure

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32
Q

tympanic cavity is

A

the space w/i the petrous portion of the temporal bone

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33
Q

the tympanic cavity contains the ossicles which

A

transmit sound vibrations from TM to the inner ear mechanism

34
Q

Tympanic cavity is lined w … communicates with ….

A

mucous membrane

communicates w nasopharynx by eustachian tube

communicates w mastoid air cells by mastoid antrum

35
Q

tympanic cavity can be divided into 2 parts

A

tympanic cavity proper - lies opposite the tympanic membrane

epitympanic recess (attic) - part of the tympanic cavity above the limits of the TM - head of malleus and most of the incus are w/i the epitympanic recess

36
Q

size of the tympanic cavity - which dimension is smallest?

A

very small cavity approx 2 cm cubed

vertical 15mm
ant/post 15mm
transverse (lat/med) = 6mm superiorly, 2mm opposite umbo of TM

37
Q

tympanic cavity can be thought as a ___ sided ___

A

6 sided box

floor, roof, anterior wall, posterior wall, medial wall, lateral wall

38
Q

what are the walls of the tympanic cavity made of

A

all walls are bony except the lateral wall, which is the tympanic membrane

39
Q

floor of the tympanic cavity is the … and contains the …

A

jugular wall

thin plate of bone overlying the jugular fossa

contains the tympanic canaliculus - near the medial wall

40
Q

roof of the tympanic cavity is the …. also called the…. directly above the roof is the

A

tegmental wall

thin plate of bone called tegmen tympani

middle cranial fossa

41
Q

the anterior wall is relatively small because

A

the roof and floor slope toward each toher

42
Q

the upper most structure of the anterior wall is the

A

canal of the tensor tympani muscle

43
Q

tensor tympani m is enclosed in

A

a bony canal above the eustachian tube - separated by a thin shelf of bone called processes cochleariformis

44
Q

opening of the eustachian tube into the tympanic cavity is located

A

just below the tensor tympani m on anterior wall

45
Q

on the anterior wall is the _____ fissure, where ______ of CN VII exits the tympanic cavity

A

petrotympanic fissure
chorda tympani

46
Q

Tubes placed in ear if there is a faulty eustachian tube …. where is it placed and why?

A

middle ear is filled with air because of the eustachian tube, so if this tube is not functioning the air cannot be maintained, mucous may build up …. need another tube to equivalize pressure, so they put a tube through the pars tensa so that they can equalize this pressure and maintain air in the middle ear

skin of TM will grow around it and eventually tube will need to be replaced

47
Q

the posterior wall is _____ and its lower portion is made of _____

A

incomplete
bone

48
Q

upper portion of the posterior wall consists of

A

an opening called the aditus through which the tympanic cavity is in communication w the mastoid antrum and mastoid air cells

49
Q

mastoid air cells

A

series of communicating mucosa-lined air filled spaces located w/i the mastoid part of the temporal bone

assist in pressure equalization w/i the TC

50
Q

pyramidal eminence is ….and is located on ….

A

a conical projection of bone near the junction w the medial wall - on posterior wall tho

close to oval window

51
Q

stapedius m is enclosed in….

A

the pyramidal eminence - tendon passes from the pyramid to the neck of the stapes

52
Q

posterior canaliculus is on the …. what enters through it?

A

posterior wall - near supero-posterior edge of TM

chorda tympani of CN VII enters TC thru it

53
Q

what is the lateral wall

A

TM w attached handle of malleus

chorda tympani crosses the upper part of the TM along its course from the posterior wall to its exit on the anterior wall

54
Q

median wall is also called the _____ wall and forms the ____ surface of the inner ear

A

labyrinthine wall
lateral surface

55
Q

surface of the median wall is

A

furrowed and lodges the nerves of the tympanic plexus (CN IX fibres that provide sensory inn of middle ear)

56
Q

the promontory is … and is located on…

A

prominent buldge that is formed by the basal turn of the cochlea of the inner ear

on median wall

57
Q

fenestra vestibuli aka oval window is located ….. and leads to/is closed by

A

on median wall

above and behind promontory

leads to scala vestibuli of the inner ear

closed/covered by the base or footplate of the stapes

58
Q

fenestra cochleae aka the round window is located … and is closed by…

A

median wall
located below and posterior to promontory

end of scala tympani of inner ear

closed by the secondary tympanic membrane

59
Q

processes cochleariformis is located on … it is a … what tendon is involved

A

the median wall

thin curled ledge of bone that separates the canal for the tensor tympani muscle from the bony part of the eustachian tube

tendon of the tensor tympani m lies on this bony shelf prior to turning and inserting on the handle of the malleus

60
Q

how are the ossicles held in the TC?

A

suspended via 8 ligaments - the joints are synovial

61
Q

the ossicles are … and transmit…

A

3 bones that form a chain across the TC

malleus, incus, stapes

transmit sound vibrations

62
Q

malleus attaches to ____, incus articulates with ___ and _____, stapes attaches to _______

A

TM

Incus w/ malleus and stapes

stapes attaches to fenestra vestibuli

63
Q

since the malleus, incus, stapes are connected via synovial joints that means

A

they are subject to all probs associated w synovial joints like arthritis

64
Q

describe dev of ossicles

A

reach final size and are completely ossified at birth

65
Q

tensor tympani: O, I, A, Inn

A

O = cartilage of eustachian tube and adjoining greater wing of sphenoid
I = tendon inserts onto upper end of manubrium of the malleus
A = tenses the tympanic membrane by drawing the malleus medially
Inn = CN V

66
Q

stapedius: O, I, A, Inn

A

O = internal walls of pyramidal eminence on posterior wall of tympanic cavity
I = neck of stapes, via stapedius tendon
A = rotates stapes posteriorly (prevents excessive oscillations)
Inn = CN VII (stapedial branch)

67
Q

describe the acoustic reflex

A

stapedius muscle applies a force to footplate of stapes, reducing amplitude of footplate’s movement, reducing sound pressure level reaching cochlea

stimulation of either ear results in response in both ears

68
Q

the acoustic reflex is a basic protective mechanism for the cochlea as it

A

is triggered by loud sounds (>85 dB SPL)

attenuates intensity of own speech

most effective for low frequencies

69
Q

the eustachian tube provides…

A

communication bw TC and nasopharynx

70
Q

the eustachian tube is about ___ cm long, has a ____ and ____ part

A

3.5 cm
bony and cartilaginous

71
Q

the eustachian tube allows for…. describe opening/closing

A

allows for aeration of the middle ear sys and clears mucous from the ME into the nasopharynx

opening = equalizes pressure in the ME w atmospheric pressure, thereby permitting free movement of the TM

closing = protects ME from pressure fluctuations and loud sounds

72
Q

whats the bad part of having a eustachian tube…. how is this avoided?

A

inadvertently forms passageway for infections to travel from nasopharynx to middle ear

mucocilliary action drains mucous away from ME into NP, in attempts to prevent infection from travelling up into ME

73
Q

in infants the ET is ____ long, and is more _____

A

18 mm
more horizontal, less angulated

74
Q

in adults the ET is ____ long, direct ____ and _____ from ME

A

36 mm
directed downward and forward, medially

75
Q

as orientation of the ET changes during dev, it….

A

dec the likelihood for bacteria to pass from NP to ME

76
Q

lateral 1/3 of ET is ____ and medial 2/3 of ET is ____

A

bony
cartilaginous

77
Q

describe the bony part of the ET

A

arises from anterior wall of the TC

passes thru petrous portion of temporal bone

opens on the base of the skull bw the petrous bone and sphenoid bone

78
Q

describe the cartilaginous part of the ET

A

lateral end joins bony portion at petrous bone

lumen is roughly triangular in shape

wider medial end opens into the mucosa of the NP; end of cartilaginous tube raises the mucosa to form the tubal elevation aka torus tubaris

lined w resp epi (columnar ciliated cells, mucous glands)

79
Q

4 muscles originate from the ET

A

tensor veli palatinin
levator veli palatini
tensor tympani
salpinogopharyngeus m

80
Q

which muscles open the cartilaginous part of the ET

A

tensor veli palatini (does most of the work)
levator veli palatini
tensor tympani

81
Q

which muscle helps to close the ET

A

salpingopharyngeus m

82
Q

otitis media is….

A

any condition in which fluid accumulates in the middle ear

ET does not allow equalization of pressure bw ME and enviro

relative neg pressure can dev in ME

serous fluid is drawn into the ME from the blood of the ME tissues, and mucous secretion can also be stimulated from ME tissues

may need tube in TM

ANAT + PHYS (9610) (21 decks)

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