Development of the Face and Palate

Question 1

When during embryogenesis does the external face develop?

Answer 1

Week 4-6

Completed by week 6

Question 2

When does the palate begin to develop during embryogenesis?

Answer 2

Week 6-8

Completed by week 12

Question 3

How many pharyngeal arches does the embryo have?

Answer 3

6

Question 4

When do the pharyngeal arches appear during embryogenesis?

Answer 4

Week 4

Question 5

How do the pharyngeal arches develop?

Answer 5

Outpouching of mesoderm on either side of pharynx

Question 6

Which structures are associated with each pharyngeal arch?

Answer 6

Branch of aorta
Cranial nerve
Cartilage bar

Question 7

What are neural crest cells?

Answer 7

Specialised cell lineage originating from neuroectoderm

Question 8

What is the migratory path of neural crest cells?

Answer 8

Neural tube forms > cells from lateral border of neuroectoderm displaced into mesoderm
Migrate through mesoderm throughout body to form structures

Question 9

At week 3 of embryogenesis, which structure appears at the future site of the face?

Answer 9

Oropharyngeal membrane

Question 10

What germ cell layers comprise the orypharyngeal membrane?

Answer 10

Ectoderm externally

Endoderm internally

Question 11

During week 4 of embryogenesis, into what future structure does the oropharyngeal membrane start to form?

Answer 11

Oral cavity

Question 12

From what two sources are the structures of the external face derived?

Answer 12

Frontonasal prominence

Mandibular and maxillary prominences

Question 13

What forms the frontonasal prominence?

Answer 13

Proliferation of mesenchymal neural crest cells ventral to forebrain

Question 14

What forms the mandibular and maxillary prominences?

Answer 14

Parts of first pharyngeal arch

Question 15

What is the space between the maxillary prominences, and is covered by the oropharyngeal membrane?

Answer 15

Stomatodeum

Question 16

Of what is the stomatodeum a precursor?

Answer 16

Mouth

Pituitary gland

Question 17

What is the process of nasal development?

Answer 17

Nasal placodes = raised bumps, appear on both sides of frontonasal prominence
Nasal placodes invaginate to form nasal pits, with medial and lateral nasal prominences on either side
Maxillary prominences expands medially > nasal prominences pushed closer to midline
Maxillary prominences fuse with nasal prominences > fuse in midline to form continuous central structure

Question 18

What are the derivatives of the frontonasal prominence?

Answer 18

Forehead
Bridge of nose
Medial and lateral nasal prominences

Question 19

What are the derivatives of the medial nasal prominence?

Answer 19

Philtrum
Primary palate
Upper 4 incisors and associated jaw

Question 20

What are the derivatives of the lateral nasal prominence?

Answer 20

Sides of nose

Question 21

What are the derivatives of the maxillary prominence?

Answer 21

Cheeks
Lateral upper lip
Secondary palate
Lateral upper lip

Question 22

What are the derivatives of the mandibular prominence?

Answer 22

Lower lip

Lower jaw

Question 23

What forms the primary palate?

Answer 23

Intermaxillary segment, formed by the fusion of the two medial nasal prominences

Question 24

Into what does the primary palate develop?

Answer 24

Anterior 1/3 of definitive palate
Labial component of philtrum
Upper 4 incisors

Question 25

What forms the palatal shelves?

Answer 25

Maxillary prominences expanding medially

Question 26

Where in the mouth do the maxillary prominences fuse in the midline?

Answer 26

Superior to tongue

Question 27

How does the tongue drop out of the way of the growing palatal shelves?

Answer 27

Developing mandible expands > increases size of oral cavity

Question 28

What forms the secondary palate?

Answer 28

Palatal shelves fusing with each other in horizontal plane

Palatal shelves fusing with nasal septum in vertical plane