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SYSTEMIC EMBRYOLOGY II > DEVELOPMENT OF THE EAR > Flashcards

DEVELOPMENT OF THE EAR Flashcards

1
Q

The ear is divided into 3 parts:

A
  1. Internal ear
  2. Middle ear
  3. External ear
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2
Q

The inner ear Consists of

  1. bony labyrinth- _______, ______, _______
  2. membranous labyrinth- _____. _______, ______
A
  1. cochlea, vestibule, and semicircular canals

2. utricle, saccule and semicircular ducts

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3
Q

The inner ear Consists of:

  1. bony labyrinth: c__hlea, ve_tibule, and sem_circular canals
  2. membranous labyrinth:
    u_ricle, sac_ule and sem_circular ducts
A
  1. cochlea, vestibule, and semicircular canals

2. utricle, saccule and semicircular ducts

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4
Q

The internal ear functions to convert sound waves into ___1___ impulses and registers changes in _________

A
  1. nerve

2. equilibrium

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5
Q

At about __ days (4 weeks) the ear begins developing as a thickening of the surface ectoderm on each side of the rhombencephalon (hind brain)

A

22 Days (4 weeks),

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6
Q

At about 22 days (4 weeks) the ear begins developing as a thickening of the surface ________ on each side of the rhombencephalon (hind brain)

A

ectoderm

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7
Q 
At about 22 days (4 weeks) the ear begins developing as a thickening of the surface ectoderm on each side of the rhombencephalon (hind brain) 
The thickenings (otic pla_odes), invaginate rapidly and form the otic or auditory vesicles (otocysts).
A

otic placodes,

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8
Q

The Otic or Auditory Vessicles divide into:

  1. V_ntral Component
    (forms saccule and cochlear duct)
  2. D_rsal Component (forms Utricle, Semicircular canals and endolymphatic ducts)
A
  1. Ventral

2. Dorsal

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9
Q

Together these epithelial structures (Ventral and Dorsal components) form the primordial membranous laby__nth

A

labyrinth

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10
Q

Ventral Component

forms sa__ule and co__lear duct

A

saccule and cochlear duct

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11
Q

Dorsal Component forms Utr_cle, Se__circular canals and en__lymphatic ducts

A

Utricle, Semicircular canals and endolymphatic ducts

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12
Q

In the development of the internal ear

Key things to NOTE on the Ventral saccular part of the otic vessicle:

A
  1. Week 6- cochlear duct grows as a tubular outpocketing from the lower pole of saccule
  2. Cochlear duct spirals in the mesenchyme to make a complete 2.5 turn at week 8
  3. The mesenchyme differentiates into cartilages
  4. Its remains connected to the saccule by a narrow pathway, the ductus reuniens
  5. The lateral wall of the cochlear duct remains attached to the surrounding cartilage by the spiral ligament and median angle is connected to and partly supported by the modiolus, the future axis of the bony cochlea.
  6. Week 10- cartilaginous shell undergoes vacuolization to form two perilymphatic spaces (scala vestibuli and scala tympani)
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13
Q

Key things to NOTE on the Ventral saccular part of the otic vessicle:

Week _ - cochlear duct grows as a tubular outpocketing from the lower pole of saccule

A

6

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14
Q

Key things to NOTE on the Ventral saccular part of the otic vessicle:

Week _ - Cochlear duct spirals in the mesenchyme to make a complete 2.5 turn

A

8

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15
Q

Key things to NOTE on the Ventral saccular part of the otic vessicle:

The mesenchyme differentiates into cartilages
Its remains connected to the saccule by a narrow pathway, the du_tus re_niens

A

ductus reuniens

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16
Q

Key things to NOTE on the Ventral saccular part of the otic vessicle:

The lateral wall of the cochlear duct remains attached to the surrounding cartilage by the spir_l ligament and median angle is connected to and partly supported by the mod_olus, the future axis of the bony cochlea

A

spiral ligament, modiolus

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17
Q

Key things to NOTE on the Ventral saccular part of the otic vessicle:

Week __- cartilaginous shell undergoes vacuolization to form two perilymphatic spaces (scala vestibuli and scala tympani)

A

10

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18
Q

Key things to NOTE on the Ventral saccular part of the otic vessicle:

The vestibular membrane separates:

  1. the c_chlear duct

from

  1. the scala v_stibule
A
  1. cochlear duct

2. scala vestibule

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19
Q

Key things to NOTE on the Ventral saccular part of the otic vessicle:

The basilar membrane separates:

  1. the c_chlear duct

from

  1. the scala ty_pani
A
  1. cochlear duct

2. scala tympani

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20
Q

Key things to NOTE on the Ventral saccular part of the otic vessicle:

The internal ear reaches its adult size and shape by the middle of the fe_al period (20-22 weeks)

A

fetal period

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21
Q

Key things to NOTE on the Ventral saccular part of the otic vessicle:

The internal ear reaches its adult size and shape by the middle of the fetal period (__ - __ weeks)

A

20-22 weeks

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22
Q

Key things to NOTE on the Ventral saccular part of the otic vessicle:

Cells of the cochlear duct become the in_er ridge and the ou_er ridge.

A

inner ridge, outer ridge.

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23
Q

Key things to NOTE on the Ventral saccular part of the otic vessicle:

1 inner row and 3-4 outer rows of aud__ory sensory hair cells are formed from the o_ter ridge

A

sensory hair cells, outer ridge

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24
Q

One inner row and 3-4 outer rows of auditory sensory hair cells are formed from the outer ridge

They are covered by the tec__rial membrane

A

tectorial membrane

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25
Q

Key things to NOTE on the Ventral saccular part of the otic vessicle:

The sensory cells and tectorial membrane together constitute the organ of ___

A

Corti

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26
Q

Key things to NOTE on the Ventral saccular part of the otic vessicle:

Spiral ganglion of cochlea is formed from migration of ganglion cells of the ve__ibulocochlear nerve along the coils of the membranous cochlea

A

vestibulocochlear nerve

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27
Q

In the development of the internal ear

Key things to NOTE on the Dorsal utricular part of otic vesicle:

A
  1. At week 6- semicircular canals appear as flattened outpocketings of the utricular part
  2. Central portions of the walls of these outpocketings disappear and give rise to three semicircular canals
  3. One end of each canal (crus ampullare) dilates and the other (crus nonampullare) does not.
  4. Two crus nonampullare fuse to give only five crura entering the utricle (three with an ampulla and two without).
  5. Cells in the ampullae form a crest (crista ampullaris) which contains sensory cells for maintenance of equilibrium.
  6. Similar sensory cells are present in the utricle and saccule as maculae acusticae (maculae utriculi
    and sacculi respectively)
  7. The endolymphatic duct and sac is formed as a diverticulum growth from the vesicle, which elongates when the otic vesicle loses its connection with the surface ectoderm
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28
Q

Key things to NOTE on the Dorsal utricular part of otic vesicle:

At week _ - semicircular canals appear as fla__ened outpocketings of the utricular part

A

6, flattened outpocketings

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29
Q

Key things to NOTE on the Dorsal utricular part of otic vesicle:

Central portions of the walls of these outpocketings disappear and give rise to three se_micircular canals

A

semicircular canals

30
Q

One end of each semicircular canal (crus ampullare) di__tes and the other two semicircular canal (crus nonampullare) does not dilate.

Next

Two crus nonampullare fuse to give only ____ crura entering the utricle (three with an ampulla and two without).

Cells in the ampullae form a crest (cr__ta ampullaris) which contains sensory cells for maintenance of equilibrium

Similar sensory cells are present in the utricle and saccule as maculae acusticae (maculae utr_uli and sa_culi respectively)

Next

The endolymphatic duct and sac is formed as a di__rticulum growth from the vesicle, which elongates when the otic vesicle loses its connection with the surface ectoderm

A

dilate,

five,

crista ampullaris,

maculae utriculi and sacculi

diverticulum growth

31
Q

crista a__ullaris which contains sensory cells for maintenance of equilibrium.

A

crista ampullaris

32
Q

sensory cells are present in the utricle and saccule as maculae acust__ae (maculae utriculi and sacculi respectively)

A

maculae acusticae

33
Q

Development of the Middle ear

Consists of :

  1. Ty__panic cavity
  2. Au__ory tube
  3. O__icles
A
  1. Tympanic cavity
  2. Auditory tube
  3. Ossicles
34
Q

Development of the Middle ear

Consists of :

A
  1. Tympanic cavity
  2. Auditory tube
  3. Ossicles
35
Q

Development of the Middle ear…

  1. Tympanic Cavity originates in the endoderm derived from the first pha__ngeal pouch
  2. The first pharyngeal pouch expands laterally to meet the floor of the first ph__ngeal cleft (groove).
  3. The distal part of the pouch (tuboty__anic recess) widens and gives rise to the primitive tympanic cavity
  4. The proximal part remains narrow and forms the au__ory tube (pharyngotympanic/eustachian tube)
A
  1. first pharyngeal pouch
  2. first pharyngeal cleft
  3. tubotympanic recess
  4. Auditory Tube
36
Q

Tympanic Cavity originates in the __________ derived from the first pharyngeal pouch

37
Q

The first pharyngeal pouch expands laterally to meet the floor of the first _______ cleft (groove).

A

pharyngeal

38
Q

The distal part of the pouch (tubotympanic recess) widens and gives rise to the primitive ________ cavity

39
Q

The proximal part remains narrow and forms the ________ ____(pharyngotympanic/eustachian tube)

A

auditory tube

40
Q

The Ossicles (Malleus, Incus, Stapes) appear during the ______ half of foetal life and remain embedded in mesenchyme until the 8th month before the surrounding tissue dissolves

41
Q

They appear during the first half of foetal life and remain embedded in mesenchyme until the _th month before the surrounding tissue dissolves

42
Q

The __________ epithelium connects the ossicles and the tympanic cavity

The supporting ligaments of the ossicles develop later within these mesenteries

A

endodermal epithelium

43
Q

The ______ and ______ are derived from cartilage of the first pharyngeal arch.

A

malleus and incus

44
Q

The ________ ______ muscle of the malleus is thus innervated by mandibular branch of trigeminal nerve

A

tensor tympani

45
Q

The tensor tympani muscle of the malleus is thus innervated by __________ branch of trigeminal nerve

A

mandibular

46
Q

The _______ -derived from second pharyngeal arch

47
Q

The ________ muscle of the stapes is innervated by the facial nerve.

48
Q

The stapedius muscle of the stapes is innervated by the ______ nerve.

49
Q

During late foetal life, ________ /mastoid antrum is formed by dorsal expansion of the tympanic cavity by vacuolization of surrounding tissue

A

tympanic/mastoid antrum

50
Q

After birth, the epithelium of the tympanic cavity invades the developing _________ process to form epithelium-lined air sacs

Later, most of the mastoid air sacs come in contact with the antrum and tympanic cavity

51
Q

External ear Consists of:

A
  1. The auricle
  2. Tympanic membrane
  3. External acoustic (auditory) meatus
52
Q

_______________ may be as a result of abnormal develop of the membranous and bony labyrinths
Or malformations of the auditory ossicles and ear drum

Tympanic cavity and external meatus are absent in extreme cases

A

Congenital hearing loss

53
Q

Congenital hearing loss ________________________________________________________________________________________

A

may be as a result of abnormal develop of the membranous and bony labyrinths
Or malformations of the auditory ossicles and ear drum

Tympanic cavity and external meatus are absent in extreme cases

54
Q

____________ Are skin tags and shallow depressions respectively anterior to the ear

Pits may indicate abnormal development of the auricular hillocks

Appendages (tags) may be due to accessory hillocks.

A

Preauricular appendages and pits

55
Q

Preauricular appendages and pits are ___________________________________________________________ ________________________________________

A

Are skin tags and shallow depressions respectively anterior to the ear

Pits may indicate abnormal development of the auricular hillocks

Appendages (tags) may be due to accessory hillocks.

56
Q

___________ is the absence of the auricle

It is rare but is commonly associated with the first pharyngeal arch syndrome

it results from failure of mesenchymal proliferation

57
Q

what is Anotia?

A

is the absence of the auricle

It is rare but is commonly associated with the first pharyngeal arch syndrome

it results from failure of mesenchymal proliferation

58
Q

__________ is a small or rudimentary auricle occurring as a result of suppressed mesenchymal proliferation

May be an indicator of associated anomalies, such as an atresia of the external acoustic meatus and middle ear anomalies.

59
Q

Microtia is a ?

A

a small or rudimentary auricle occurring as a result of suppressed mesenchymal proliferation

May be an indicator of associated anomalies, such as an atresia of the external acoustic meatus and middle ear anomalies.

60
Q

______________ is rare occurrence

usually the auricle is normal

Occurs as a result of failure of inward expansion of the first pharyngeal groove and failure of the meatal plug to disappear

A

Absence of the External Acoustic Meatus

61
Q

Absence of the External Acoustic Meatus

A

is rare occurrence

usually the auricle is normal

Occurs as a result of failure of inward expansion of the first pharyngeal groove and failure of the meatal plug to disappear

62
Q

Development of the External Auditory Meatus

External Auditory Meatus develops from the dorsal portion of the first ____________ cleft or groove

A

pharyngeal cleft or groove

63
Q

Development of the External Auditory Meatus

3rd month-proliferation of epithelial cells at the bottom of the meatus, forming a solid _______ plate (meatal plug)

A

solid epithelial plate (meatal plug)

64
Q

Development of the External Auditory Meatus

7th month- meatal plug _______ , epithelial lining of the floor of the meatus participates in formation of the definitive eardrum (tympanic membrane)

65
Q

Development of the External Auditory Meatus

Congenital deafness occurs if the ____________ persists until birth

A

meatal plug

66
Q

Tympanic Membrane consists of

  1. E__oderm of the first pharyngeal cleft or groove
  2. Endoderm of the t____ympanic recess, a derivative of the first pharyngeal pouch
  3. Mesenchyme of the first and second p__ryngeal arches
A
  1. Ectoderm
  2. tubotympanic recess
  3. pharyngeal arches
67
Q

Tympanic Membrane consists of

A
  1. Ectoderm of the first pharyngeal cleft or groove
  2. Endoderm of the tubotympanic recess, a derivative of the first pharyngeal pouch
  3. Mesenchyme of the first and second pharyngeal arches
68
Q
  1. Auricle: develops ___________________
  2. External audirory meatus : develops _____________________
  3. Middle ear cavity; auditory tube, mastoid air cells: develops _________________
  4. Cochlea and semicircular canals: develops ________________________
  5. Tympanic membrane: develops from ____________________________
  6. Ear Ossicles: __________________________

__________________

A
  1. Auricle: develops Mesenchyme of the 1st and 2nd pharyngeal groove
  2. External audirory meatus : develops from 1st pharyngeal groove (Ectoderm)
  3. Middle ear cavity; auditory tube, mastoid air cells: develops 1st pharyngeal pouch (Endoderm)
  4. Cochlea and semicircular canals: develops otic placodea/ otocyst
  5. Tympanic membrane: develops from 1st pharyngeal membrane ( ectoderm and endoderm) with intervening mesenchyme
  6. Ear Ossicles: 1st pharyngeal arch cartilage (incus and malleus)

2nd pharyngeal arch cartilage (stapes)

69
Q

Auricle: develops _______ of the 1st and 2nd pharyngeal groove

External audirory meatus : develops from 1st pharyngeal groove (_________)

Middle ear cavity; auditory tube, mastoid air cells: develops 1st pharyngeal pouch (_________)

Cochlea and semicircular canals: develops _______ _____/ _______

Tympanic membrane: develops from 1st pharyngeal membrane ( __________ and ________) with intervening mesenchyme

Ear Ossicles: 1st pharyngeal arch cartilage (______ and ______ )

2nd pharyngeal arch cartilage (_______)

A
  1. Mesenchyme
  2. Ectoderm
  3. Endoderm
  4. otic placode/ otocyst
  5. ectoderm and endoderm
  6. incus and malleus
  7. stapes
70
Q

________ is commonly associated with the first pharyngeal arch syndrome

it results from failure of mesenchymal proliferation

SYSTEMIC EMBRYOLOGY II (2 decks)

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