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Flashcards in Embryology 2 Deck (24)
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1

What are neural crest cells

Specialised cells from lateral neurectoderm which migrate to enter the mesoderm

2

What is the facial skeleton derived from

Neural crest cells of the 1st pharyngeal arch

3

What is the facial primordia derived from

1st pharyngeal arch
Frontonasal prominence

4

What is the stomatodeum

Depression in embryonic face with buccopharyngeal membrane at centre
It is between the FNP and maxillary and mandibular prominences

5

What is a placode

Ectodermal thickening that gives rise to an organ of special sense

6

Describe nose development

Nasal placodes on FNP invaginate to form nasal pits with medial and lateral nasal prominences
Maxillary prominence growth pushes nasal prominences towards midline
Maxillary prominences fuse with medial nasal prominences
Medial nasal prominences fuse with each other a the midline
This forms the intermaxillary segment

7

What is the intermaxillary segment composed of

Labial - philtrum
Upper jaw - incisors
Palate - primary palate

8

Describe formation of the definitive palate

Palatine shelves grow down from maxillary prominences on each side of the developing tongue
Mandible grows so tongue drops
Palatine shelves grow towards each other and fuse at the midline
Nasal septum grows down to fuse with the palatine shelves

9

What is a lateral cleft lip

Failure of fusion of medial nasal prominence and maxillary prominence

10

What is a cleft palate

Failure of fusion of palatine shelves

11

Fate of FNP

Forehead
Bridge of nose
Medial and lateral nasal prominences

12

Fate of medial nasal prominence

Philtrum
Primary palate
Mid upper jaw

13

Fate of lateral nasal prominence

Sides of nose

14

Fate of maxillary prominence

Cheeks
Lateral upper lip and jaw
Secondary palate

15

Fate of mandibular prominence

Lower jaw and lip

16

Describe eye development

Optic vesicles (from forebrain - diencephalon) grow and contact optic placodes
Optic placodes invaginate and pinch off
Placode becomes lens and vesicle becomes retina

17

Where do eye primordia initially form
Why does this need to change

Initially on side of head
Growth of facial prominences push eyes to front to give binocular vision

18

What is binocular vision

Overlapping fields of view

19

What is the EAM derived from

1st pharyngeal cleft

20

What are the auricles derived from

Proliferation of 1st and 2nd pharyngeal arches surrounding the EAM

21

Describe internal ear development

Invagination of otic placodes creates auditory vesicles
These vesicles develop into the membranous labyrinth (cochlea and canal system) to give hearing and balance sense

22

Describe external ear development

Initially in neck
Growth of mandible causes ascent of ears to the side of the head in line with the eyes

23

What can alcohol cause if it crosses the placenta and why

Fetal alcohol syndrome
Alcohol related neurodevelopment delay

Alcohol affects neural crest migration and brain development

24

Features of FAS

Thin upper lip
Short nose
Smooth philtrum
Small head
Low nasal bridge
Small eye openings
Underdeveloped jaw
Flat midface