Development of the Ear and Eye

Question 1

What is a placode?

Answer 1

Thickened ectodermal patches on the developing head

Question 2

What are the pharyngeal apparatus?

Answer 2

Series of external ridges and furrows with corresponding internal pouches

Question 3

What is the function of the internal ear?

Answer 3

Converts sound into electrical impulses

Question 4

Which nerve innervates the inner ear apparatus?

Answer 4

Vestibulocochlear

Question 5

Which 2 structures make up the inner ear?

Answer 5

Cochlear and Semicircular canals

Question 6

How does ear development start?

Answer 6

Otic placodes form

Question 7

What happens to the otic placodes as they develop?

Answer 7

Invaginate into the developing head to form the otic vesicles

Question 8

What does the ventral portion of the otic vesicle become?

Answer 8

Saccule and cochlear duct

Question 9

What does the dorsal portion of the otic vesicle become?

Answer 9

Utricle, semicircular canals and endolymphatic duct

Question 10

What 2 things make up the Organ of Corti?

Answer 10

Sensory hair cells

Tectorial membrane

Question 11

What is the function of the middle ear?

Answer 11

Conduct sound from the external acoustic meatus to the inner ear

Question 12

What area is the middle ear derived from?

Answer 12

1st pharyngeal pouch

1st and 2nd pharyngeal cartilage

Question 13

Which pharyngeal cartilage develops into the malleus and incus?

Answer 13

1st pharyngeal cartilage

Meckel’s cartilage

Question 14

Which pharyngeal cartilage develops into the stapes?

Answer 14

2nd pharyngeal cartilage

Reichert’s cartilage

Question 15

What structure is created by the narrowing of the 1st pharyngeal pouch proximally?

Answer 15

Eustachian tube

Question 16

What does the external ear develop from?

Answer 16

Dorsal portion of the 1st pharyngeal cleft

Question 17

What are the 3 layers of the tympanic membrane?

Answer 17

Ectoderm, mesoderm and endoderm layers

Question 18

Where do the external ears initially develop?

Answer 18

Neck

Question 19

In what week does the eye start developing?

Answer 19

4th week

Question 20

Describe the initial process of eye formation?

Answer 20

Outpocketings of the forebrain called the optic vesicles grow to make contact with the overlying ectoderm to form the optic placode.

Question 21

Decreibe the appearance of the optic cup

Answer 21

Inner and outer layer separated by a lumen creating the intraretinal space

Question 22

What does the inferior surface of the optic cup become and what is its function?

Answer 22

Choroid fissure- carries hyaloid artery

Question 23

What is the outer layer of the optic cup also known as?

Answer 23

Pigmented layer

Question 24

What do the cells in the inner layer of the optic cup differentiate into?

Answer 24

Cons
Rods
Optic nerve
Neurones

Question 25

What does the hyaloid artery become?

Answer 25

Central artery of the retina

Question 26

What does the rim of the optic cup differentiate into?

Answer 26

Iris

Ciliary body

Question 27

What does the loose mesenchyme surrounding the eye develop into?

Answer 27

Choroid

Sclera

Question 28

What do the extraocular muscles develop from in the eye?

Answer 28

Preotic myotomes

Question 29

What is coloboma?

Answer 29

Failure of the choroid fissure to fuse