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Neuro Exam 3 > Ear anatomy and embryology > Flashcards

Ear anatomy and embryology Flashcards

1
Q

what is the function of the auricle?

A

collect airwaves and funnel them into external acoustic meatus.

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2
Q

what is the auricle made up of (structure)

A

cartilages
depressions (concha and schaphoid)
lobule –> composed of fibroelastic tissue

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3
Q

what is the blood supply to the auricle

A

posterior auricle artery and vein

superficial temporal artery and vein

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4
Q

what is the innervation to the auricle

A

greater auricular (C2, C3) and lesser occipital

auriculotemporal
facial n
vagus n.

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5
Q

what is the lymphatic drainage of the auricle

A

mastoid, parotid lymph nodes –> deep cervical

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6
Q

what is the external acoustic meatus

what bone is it in
what is it lined with
what is the lateral 1/3 and the medial 2/3 made up of

A
  1. Canal traveling through tympanic portion of temporal bone to tympanic membrane.
  2. Canal traveling through tympanic portion of temporal bone to tympanic membrane.
  3. Lined by stratified squamous epithelium containing numerous ceruminous glands.
  4. Lateral 1/3 is cartilaginous; medial 2/3 is bony
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7
Q

what is the blood supply to the external acoustic meatus (3)

A

a. Posterior auricular a. and v.
b. Superficial temporal a. and v.
c. Deep auricular a

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8
Q

what is the innervation of the external acoustic meatus

A

auricular temporal nerve (V3)

vagus n.

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9
Q

what is the lymphatic drainage of the external acoustic meatus

A

deep cervical lymph nodes

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10
Q

what is otitis external

A

inflammation of the external ear

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11
Q

what is the tympanic membrane attached to

A

handle of malleus

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12
Q

what is the function of the tympanic membrane

A

convert sound waves into vibrations of middle ear ossicles.

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13
Q

what does the tympanic membrane separate?
what is it covered with externally
and what covers it internally
which direction is the TM directed

A

a. Semitransparent, fibroelastic membrane
b. Separates external and middle ear.
c. Covered by epidermis externally; mucus membrane internally.
d. The membrane is directed anteriorly and inferiorly.

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14
Q

what is the umbo

A

central concavity of the TM

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15
Q

what is the pars flaccida and pars tensa

A

b. Pars flaccida – superior, thin-walled portion

c. Pars tensa – inferior, thick-walled portion

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16
Q

what is the blood supply to external TM

what is the innervation to the external TM

A

blood–> deep auricular branch of maxillary

GSA –> auriculotemporal nerve
Vagus n.

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17
Q

what is the blood supply to the internal TM?

what is the innervation to the internal TM

A

blood_–> anterior tympanic off maxillary

innervation–> GVA tympanic branch of glossopharyngeal

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18
Q

why is the TM a source of the cough reflex?

A

b/c of CN V being touched on the external surface of the TM

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19
Q

what arches is the auricle derived from

A

first and second pharyngeal arches.

6 auricular hillocks will later fuse to form the definitive auricle

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20
Q

defects of the auricle are commonly associated with what else?

A

chromosomal syndromes

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21
Q

what is the external auditory meatus formed from

what is the meatal plug and what is its fate

what is a clinical correlation of the meatal plug

A

first pharyngeal cleft

b. Meatal plug forms from proliferation of epithelial cells; by 7th month degenerates.
c. CLINICAL CORRELATION: Persistence of meatal plug can cause deafness.

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22
Q

external epithelium of tympanic membrane is derived from what

A

ectoderm of first pharyngeal cleft

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23
Q

middle CT of TM is derived from what

A

mesoderm of first pharyngeal arch

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24
Q

internal epithelium of TM is derived from what

A

endoderm of the first pharyngeal POUCH

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25
Q

what is in the middle ear

A

tympanic cavity–> mucous membrane-lined space within portion of the temporal bone and auditory ossicles

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26
Q

what is the function of the middle ear

A
  1. Transfer of sound waves from gas to liquid medium (from external to internal ear).
  2. Amplification of sound waves via vibration of bony ossicles.
  3. Protective response to loud sounds (via tensor tympani & stapedius mm).
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27
Q

what is the roof of the tympanic cavity

what does it separate

A

tegmen tympani –> separates epitympanic recess from middle cranial fossa

28
Q

floor of tympanic cavity

what does it separate

A

segment of temporal bone separating middle ear from internal jugular vein

29
Q

what is the lateral wall of the tympanic cavity

A

tympanic membrane

30
Q

what is the medial wall of the tympanic cavity

what are the components

A

bony wall separating middle from internal ear

promontory
oval window
round window

31
Q

what is the promontory

A

mound of bone created by cochlea

32
Q

what is the oval window

A

fenestra vestibule
superior to the round window

opens to vestibule of internal ear
contacted by the stapes
transmits motion of stapes to fluid of internal ear

33
Q

what is the round window (fenestra cochlea)

A

opens to scala tympani
covered with a thin membrane

acts as a pressure release valve for fluids of the internal ear

34
Q

what is the aditus ad antrum

A

entrance to the mastoid antrum

35
Q

what is the posterior wall of the tympanic cavity

A

temporal bone

aditus ad antrum
facial canal

36
Q

what is mastoiditis

and why is it clincally significant

A

middle ear infections can sometimes spread to the mastoid air cells via the aditus ad antrum (opening to these air cells)

37
Q

what is the anterior wall of the tympanic cavity

what openings are in it

A

segment of temporal bone separating middle ear from carotid canal

opening for pharyngotympanic tube (aka auditory tube) and semi-canal (passage of tensor tympani).

38
Q

what is the pharyngotympanic tube

what is it lined by
what does it connect
what is its function
posterolateral third is made by what
anteromedial 2/3s

what muscle can open this tube and what is its innervation

A

auditory tube

  1. Mucous-membrane lined tube connecting middle ear and nasopharynx.
  2. Function – balances pressure on external and internal sides of tympanic membrane.
  3. Posterolateral third is bony; anteromedial 2/3 is cartilaginous.
  4. Tensor veli palatini muscle can open the membranous tube (CN V3
39
Q

what are the auditory ossicles

A

malleus

incus
stapes

40
Q

malleus

A

contacts TM
creates umbo
vibrates in response to movment of the TM

41
Q

incus

A

body articulates with head of malleus

long limb articulates with stapes

42
Q

stapes

A

base–> contacts oval window

vibration of stapes induces motion of the fluid within the cochlear duct

43
Q

what are the 2 muscles of the middle ear

A

stapedius

tensory tympani

44
Q

stapedius
attachments
function
innervation

A

a. Origin – posterior wall of tympanic cavity (pyramidal eminence)
b. Insertion – stapes
c. Function – dampens movements of ossicles
d. Innervation – facial nerve (CN VII; SVE)

45
Q

tensor tympani
attachments
function
innervation

A

a. Origin – cartilaginous part of pharyngotympanic tube
b. Insertion – malleus
c. Function – dampens movements of ossicles
d. Innervation – trigeminal nerve (V3; SVE)

contracts when we are chewing or speaking

46
Q

what is the cause of hyperacusis

A

paralysis of middle ear muscles can can this

excessive hearing acuteness due to loss of dampening

47
Q

what is the blood supply to the middle ear? *5

veins?

A
  1. Inferior tympanic a (from ascending pharyngeal a)
  2. Anterior tympanic a ( 2nd branch from maxillary a)
  3. Posterior tympanic a (from stylomastoid a.)
  4. Superior tympanic (from middle meningeal a.)
  5. Artery of pterygoid canal (tubal branches to pharyngotympanic tube).
  6. Venous drainage to ptergyoid plexus
48
Q

what type of joints are the ossicles?

A

synovial

as we age they can undergo oto sclerosis and these can fuse! so we have shit hearing

49
Q

what are the two nerves of the middle ear?

A

CN IX

CN VII

50
Q

what are the three branches given off by CN VII

A 
nerve to stapedius (SVE)
greater petrosal (GVE-P )
chorda tympani (SVA and GVE-P)
51
Q

what are the branches given off by CN IX in the middle ear?

A

tympanic branch (GVA, GVE-P)

turns into lesser petrosal –> parotid gland

52
Q

otitis media

A

inflammation of the middle ear–> often due to spread of infection from pharynx via pharyngo tympanic tube

53
Q

what are the tympanic cavity and the auditory derived from

A

first pharyngeal pouch

54
Q

malleus, incus and tensor tympani are derived from what

A

first pharyngeal arch

55
Q

stapes and stapedius muscle are derived from wha

A

2nd pharyngeal arch

56
Q

what is clinically significant about the stapes and its connection to the oval window

A

if it becomes congenitally ossified then deafness will ensue

conductive hearing loss

57
Q

where is the internal ear?

what does it contain

A

housed in the petrous portion of the temporal bone

internal ear contains the vestibulocochlear organ involved in balance and hearing

58
Q

what is inside the bony labyrinth

A

perilymph
cochlea
vestibule
semicircular canals

59
Q

what is inside the membranous labyrinth

A

endolymph

all portions innervated by CN VIII

60
Q

what is the endolymphatic duct

A

maintains the volume and composition of endolymphatic fluid

must have high K concentration

61
Q

what is the cochlear duct

A

organ of hearing

vestibular membrane- roof
basilar membrane - floor
spiral organ of corti - hair cells

62
Q

what are the two components of the vestibulocochlear nerve (CNVIII)

A
  1. Vestibular portion innervates semicircular ducts, utricle, and saccule to carry proprioceptive information (movements of the head) to the brain.
  2. Cochlear portion innervates cochlear duct to carry information about sound to the brainstem (spiral organ)
63
Q

what is the membranous labyrinth derived form

A

otic placode –> otic sac–> otic vesicle

64
Q

what is the path of production of sound

A
  1. Airways travel down external acoustic meatus causing vibration of tympanic membrane.
  2. Motion of the tympanic membrane causes vibration of the three middle ear ossicles.
  3. Footplate of stapes contacts oval window and causes movement of the fluid in the inner ear.
  4. Movement of fluid in the cochlear duct causes bending of the hair cells imbedded within the spiral organ.
  5. Bending of these hair cells initiates signaling events which ultimately lead to propagation of a nerve impulse along the cochlear portion of CN VIII.
65
Q

what is bony labyrinth derived from?

A

surrounding mesenchyme (vestibule, semicirucular canals, cochlea)

Neuro Exam 3 (12 decks)

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