DEVELOPMENT OF THE EAR

Question 1

The ear is divided into 3 parts:

Answer 1

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

Question 2

The inner ear Consists of

1. bony labyrinth- _______, ______, _______
2. membranous labyrinth- _____. _______, ______

Answer 2

1. cochlea, vestibule, and semicircular canals

2. utricle, saccule and semicircular ducts

Question 3

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

Answer 3

1. cochlea, vestibule, and semicircular canals

2. utricle, saccule and semicircular ducts

Question 4

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

Answer 4

1. nerve

2. equilibrium

Question 5

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

Answer 5

22 Days (4 weeks),

Question 6

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

Answer 6

ectoderm

Question 7

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).

Answer 7

otic placodes,

Question 8

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)

Answer 8

1. Ventral

2. Dorsal

Question 9

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

Answer 9

labyrinth

Question 10

Ventral Component

forms sa__ule and co__lear duct

Answer 10

saccule and cochlear duct

Question 11

Dorsal Component forms Utr_cle, Se__circular canals and en__lymphatic ducts

Answer 11

Utricle, Semicircular canals and endolymphatic ducts

Question 12

In the development of the internal ear

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

Answer 12

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)

Question 13

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

Answer 13

6

Question 14

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

Answer 14

8

Question 15

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

Answer 15

ductus reuniens

Question 16

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

Answer 16

spiral ligament, modiolus

Question 17

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)

Answer 17

10

Question 18

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

The vestibular membrane separates:

1. the c_chlear duct

from

2. the scala v_stibule

Answer 18

1. cochlear duct

2. scala vestibule

Question 19

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

The basilar membrane separates:

1. the c_chlear duct

from

2. the scala ty_pani

Answer 19

1. cochlear duct

2. scala tympani

Question 20

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)

Answer 20

fetal period

Question 21

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)

Answer 21

20-22 weeks

Question 22

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.

Answer 22

inner ridge, outer ridge.

Question 23

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

Answer 23

sensory hair cells, outer ridge

Question 24

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

Answer 24

tectorial membrane

Question 25

Key things to NOTE on the Ventral saccular part of the otic vessicle: The sensory cells and tectorial membrane together constitute the organ of ___

Answer 25

Corti

Question 26

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

Answer 26

vestibulocochlear nerve

Question 27

In the development of the internal ear Key things to NOTE on the Dorsal utricular part of otic vesicle:

Answer 27

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

Question 28

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

Answer 28

6, flattened outpocketings

Question 29

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

Answer 29

semicircular canals

Question 30

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

Answer 30

dilate, five, crista ampullaris, maculae utriculi and sacculi diverticulum growth

Question 31

crista a__ullaris which contains sensory cells for maintenance of equilibrium.

Answer 31

crista ampullaris

Question 32

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

Answer 32

maculae acusticae

Question 33

Development of the Middle ear Consists of : 1. Ty__panic cavity 2. Au__ory tube 3. O__icles

Answer 33

1. Tympanic cavity 2. Auditory tube 3. Ossicles

Question 34

Development of the Middle ear Consists of :

Answer 34

1. Tympanic cavity 2. Auditory tube 3. Ossicles

Question 35

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)

Answer 35

1. first pharyngeal pouch 2. first pharyngeal cleft 3. tubotympanic recess 4. Auditory Tube

Question 36

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

Answer 36

endoderm

Question 37

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

Answer 37

pharyngeal

Question 38

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

Answer 38

tympanic

Question 39

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

Answer 39

auditory tube

Question 40

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

Answer 40

first

Question 41

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

Answer 41

8th

Question 42

The __________ epithelium connects the ossicles and the tympanic cavity The supporting ligaments of the ossicles develop later within these mesenteries

Answer 42

endodermal epithelium

Question 43

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

Answer 43

malleus and incus

Question 44

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

Answer 44

tensor tympani

Question 45

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

Answer 45

mandibular

Question 46

The _______ -derived from second pharyngeal arch

Answer 46

stapes

Question 47

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

Answer 47

stapedius

Question 48

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

Answer 48

facial

Question 49

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

Answer 49

tympanic/mastoid antrum

Question 50

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

Answer 50

mastoid

Question 51

External ear Consists of:

Answer 51

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

Question 52

_______________ 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

Answer 52

Congenital hearing loss

Question 53

Congenital hearing loss ________________________________________________________________________________________

Answer 53

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

Question 54

____________ 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.

Answer 54

Preauricular appendages and pits

Question 55

Preauricular appendages and pits are ___________________________________________________________ ________________________________________

Answer 55

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.

Question 56

___________ 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

Answer 56

Anotia

Question 57

what is Anotia?

Answer 57

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

Question 58

__________ 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.

Answer 58

Microtia

Question 59

Microtia is a ?

Answer 59

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.

Question 60

______________ 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

Answer 60

Absence of the External Acoustic Meatus

Question 61

Absence of the External Acoustic Meatus

Answer 61

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

Question 62

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

Answer 62

pharyngeal cleft or groove

Question 63

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

Answer 63

solid epithelial plate (meatal plug)

Question 64

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)

Answer 64

dissolves

Question 65

Development of the External Auditory Meatus Congenital deafness occurs if the ____________ persists until birth

Answer 65

meatal plug

Question 66

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

Answer 66

1. Ectoderm 2. tubotympanic recess 3. pharyngeal arches

Question 67

Tympanic Membrane consists of

Answer 67

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

Question 68

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: __________________________ __________________

Answer 68

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)

Question 69

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 (_______)

Answer 69

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

Question 70

________ is commonly associated with the first pharyngeal arch syndrome it results from failure of mesenchymal proliferation

Answer 70

Anotia