Ear Development: External Ear

Question 1

External ear

Answer 1

1. Auricle
2. External auditory meatus
3. Tympanic membrane

Question 2

Auricle origin

Answer 2

Mesoderm

Question 3

Auricle development

Answer 3

1. Mesoderm proliferation at 1st pharyngeal cleft entrance
2. 6 mesodermal swellings fuse together forming auricle

Question 4

External auditory meatus development

Answer 4

1. From 1st pharyngeal cleft which grows inwards to end at tympanic membrane
2. At first, meatus bottom is filled proliferated epithelial cells forming meatal plugs which dissolve by 7th month

Question 5

Tympanic membrane

Answer 5

1. Outer layer
2. Inner layer
3. Intermediate layer

Question 6

Tympanic membrane: outer layer

Answer 6

1. Ectodermal
2. Belongs to 1st pharyngeal cleft

Question 7

Tympanic membrane: inner layer

Answer 7

1. Endodermal
2. Belongs to tubotympanic recess derived from 1st pharyngeal pouch

Question 8

Tympanic membrane: intermediate layer

Answer 8

1. Mesodermal
2. Derives from mesoderm interposed between 1st cleft and 1st pouch