Embryology of the Ear

Question 1

cristae ampullaris

Answer 1

in the ampulla of each semicircular canal

Question 2

macula

Answer 2

one in the utricle and one in the saccule

Question 3

cochlear

Answer 3

numerous along the cochlear duct

Question 4

what is the thickening of ectoderm called during the fourth week of development

Answer 4

ecotderm

Question 5

the otic placode forms __________ and then _______

Answer 5

otic placode and vesicle

Question 6

_________gives rise to the membranous labyrinth

Answer 6

otic vesicle

Question 7

the otic vesicle forms what two structures

Answer 7

utricle and saccule

Question 8

the utricle forms

Answer 8

endolymphatic duct, utricle and semicircular canals

Question 9

the saccule forms

Answer 9

the saccule and cochlear duct

Question 10

the _____________ is related to the cochlear duct and is involved in hearing

Answer 10

spiral ganglion

Question 11

the ____________is involved in detection of movement of the head

Answer 11

vestibular ganglion

Question 12

the ganglia form from

Answer 12

neural crest cells

Question 13

the otic capsule helps also form what skull bone

Answer 13

petrous part of the temporal bone

Question 14

what is the space called within the otic capsule

Answer 14

perilymphatic space

Question 15

what is the fluid within the perilymphatic space called

Answer 15

perilymph

Question 16

_________can cause malformation of the cochlea and deafness

Answer 16

rubella infection

Question 17

what is the significance of the perilymphatic space and the cochlear duct

Answer 17

it is related to it twice (once above and once below)

Question 18

What are the two space of the perilymphatic space called

Answer 18

scala tympani and scala vestbuli

Question 19

what helps form the tympanic membrane

Answer 19

the first pharyngeal groove

Question 20

what is the pouch lined with

Answer 20

endoderm

Question 21

what is the groove lined with

Answer 21

ectoderm and mesenchyme

Question 22

what germ layers is the tynmpanic membrane derived from

Answer 22

ecto, endo, meso (all three!)

Question 23

the 1st pharyngeal pouch helps form

Answer 23

the middle ear which is continuous with the mastoid antrum and nasopharynx ia pharyngotympanic tube (auditory tube)

Question 24

what are the three middle ear ossicles

Answer 24

malleus, incus, and stapes

Question 25

malleus and incus are derived from

Answer 25

1st pharyngeal arch

Question 26

stapes is derived from

Answer 26

cartilage of the second arch

Question 27

tensor tympani m is attached to ________and is derived from ________arch

Answer 27

malleus; mesenchyme of first arch

Question 28

the tensor tympani is innervated by

Answer 28

CN V

Question 29

stapedius is innervated by

Answer 29

facial nerve

Question 30

external ear develps at the crossroads of

Answer 30

1st and 2nd pharyngeal arches

Question 31

what is anotonia

Answer 31

absence of an ear

Question 32

what is microtia

Answer 32

small ear

Question 33

auricular appendages

Answer 33

persistence of auricular hillocks

Question 34

what dis microtia result from

Answer 34

absence of auricular hillocks and is characterized by the absence of the auricle; this defect is associatied with other defects

Question 35

___________-are small depressions located anterior to the auricle

Answer 35

preauricular sinuses

Question 36

preauricular sinuses are the result from

Answer 36

abnormal closure of the first pharyngeal groove

Question 37

what happens when the plug of cells in front of the tynpanic membrane fail to regress

Answer 37

atresia of external auditory meatus occurs

Question 38

__________is when epidermoid tissue is within the tympanic membrane

Answer 38

congenital cholesteatome

Question 39

congenital fixation of the stapes

Answer 39

Complete absence of the annular ligament of the stapes without evidence of otosclerotic bone growth may be congenital stapes fixation.