ear embryology

Question 1

otic placodes come from:

Answer 1

thickening of surface ectoderm dorsal to 2nd pharyngeal cleft

Question 2

otic placode formation is induced by:

Answer 2

the neural tube in the region of the developing hindbrain

Question 3

otic placodes invaginate to form:

Answer 3

otic pits

Question 4

otic pits separate from surface ectoderm to form:

Answer 4

otic vesicles

Question 5

otic vesicles give rise to:

Answer 5

• membranous labyrinth of inner ear
• sensory receptors within labyrinth (hair cells)
• sensory ganglia (CN VIII)

Question 6

ectomesenchyme surrounding membranous labyrinth becomes:

Answer 6

bony labyrinth

Question 7

which cleft and pouch form the ear?

Answer 7

1st and 1st

Question 8

expanding pouch called:

Answer 8

tubotympanic recess

Question 9

distal part of tubotympanic recess becomes:

Answer 9

middle ear cavity

Question 10

proximal part of tubotympanic recess becomes:

Answer 10

eustachian tube

Question 11

malleus and incus come from which arch?

Answer 11

1st

Question 12

stapes comes from which arch?

Answer 12

2nd

Question 13

muscles associated with the ossicles come from:

Answer 13

somitomeres

Question 14

external acoustic meatus derived from:

Answer 14

1st cleft

Question 15

tympanic membrane forms from:

Answer 15

membrane between 1st pouch and 1st cleft

Question 16

which germ layers make up the tympanic membrane?

Answer 16

All three, ecto, meso, endo

Question 17

where does the auricle come from?

Answer 17

6 swellings of mesenchyme that surround the 1st cleft