Embryology of Eyes and Ears Flashcards Preview

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Flashcards in Embryology of Eyes and Ears Deck (21):
1

What do the Ossicles develop from?

Meckels Cartilage (PA 1) form Malleus and Incus
Reicharts Cartilage (PA 2) for the stapes

2

What does the middle ear develop from?

From the 1st pharyngeal pouch

3

What does the Auricle develop from?

Pharyngeal arch 1 and 2

4

What does the Inner Ear develop from?

It is the sensory part so... the otic placode

5

What does the EAM develop from?

The dorsal part of the 1st pharyngeal cleft

6

Describe the development of the middle ear

Comes from the 1st pharyngeal pouch
The pouch elongates laterally and touches the floor of the 1st cleft (External ear) a
The distal part becomes the ttubotympanic recess, widens and becomes the tympanic cavity

The proximal part becomes the Eustachian Tube

7

Describe the development of the ossicles

Comes from the Cartilage bars of PA 1 and 2
They are surrounded by tissue at the start of their development which degenerates

8

Describe the development of the ossicles

Comes from the Cartilage bars of PA 1 and 2
They are surrounded by mesenchyme until month 8 which degenerates

9

Describe the development of the auricle

The mesenchymal proliferations of arch 1 and 2 form swellings.
These swellings become the auricular hillocks which then fuse to become the auricle

10

What is the optic cup

A double layer of the optic vesicle
It has an intraretinal space which dissappears so the layers touch

11

What will the Optic Cup become?
The Rim...

It will become the pupil
The surrounding edge will become the iris and ciliary body

12

What will the Optic Cup become?
The internal part...

The Inner layer - retina
Outer layer - Choroid

13

What lies in the choroid fissure?

The hyaloid artery

14

What is on the inferior edge of the optic cup?

The Choroid Fissure

15

What happends to the contents of the Choroid Fissure?

The hyaloid artery degenerates slightly, and becomes the central retinal artery

16

When does the eye begin development?
What happens first?

Week 4
Two grooves appear on the sides of the forebrain (after the neural tube has closed). This is the optic stalk.

17

What do the optic stalks do?

They grow out towards the overlying ectoderm.
WHen they touch, the ectoderm thickens (the Optic Placode)

18

What does the Optic Placode do?

It invaginates and becomes the optic vesicle
The placode (thickened bit) will become the future retina

19

What will the optic vesicle become?

The optic cup

20

What happens to the optic cup?

The Choroid fissure fuses at week 7 and it becomes it's new parts of the eye

21

Where do extraoccular muscles come from?

They come from preotic myotomes which develop near the developing eye