Session 3

Question 1

Define Neural crest

Answer 1

A specialised population of cells that

originates within the neurectoderm

Question 2

How do the Neural crest cells reach the area for Head & Neck development?

Answer 2

Begin at the lateral border of the neuroectoderm
Become displaced and enter the mesoderm
Migrate and contribute to Head & Neck

Question 3

What are the major features of the face?

Answer 3

Palpebral fissues (Opening to the eye)
Oral fissue
Nares (Nostrils)
Philtrum (Small vertical groove above the upper lip)

Question 4

Where do the Pharyngeal arches develop?

Answer 4

In the neck region around the Aortic arches

Question 5

What does each Pharyngeal arch have?

Answer 5

Aortic arch artery
Vein
Nerve (Cranial)
Mesenchyme filling (Will become cartilaginous bar)
Ectodermal covering
Endodermal lining

Question 6

What forms the facial skeleton?

Answer 6

Neural crest of 1st Pharyngeal arch

Question 7

What forms the muscles of mastication?

Answer 7

Mesoderm of 1st Pharyngeal arch

Question 8

What forms the muscles of facial expression?

Answer 8

Mesoderm of 2nd Pharyngeal arch (First prominence)

Question 9

What is the facial primordia made of?

Answer 9

The 1st Pharyngeal arch (Paired and has 2 prominences)
Frontonasal prominence (Unpaired. Primordia of eyes)

Question 10

Why is the Frontonasal prominence large?

Answer 10

Because it surrounds the ventro-lateral part of the forebrain

Question 11

What drives development of the face?

Answer 11

Expansion of the cranial neural tube

Question 12

What is the Stomatodeum?

Answer 12

An area of the embryonic head that contains the buccopharyngeal membrane(Avascular, will rupture to create the oral cavity opening)

Question 13

What does the 1st Pharyngeal arch develop into?

Answer 13

Maxillary prominence

Mandibular prominence

Question 14

What are the derivatives of the Frontonasal prominence?

Answer 14

Forehead
Bridge of nose
Nose
Philtrum

Question 15

What are the derivatives of the Maxillary prominence?

Answer 15

Cheeks
Lateral upper lip
Lateral upper jaw

Question 16

What are the derivatives of the Mandibular prominence?

Answer 16

Low lip

Jaw

Question 17

What is a placode?

Answer 17

A thickening of ectoderm which indicates it will go on to become a ‘special senses’

Question 18

Where do the nasal placodes appear?

Answer 18

On the frontonasal prominence. They then sink to become the nasal pits (With raised section around called prominence)

Question 19

In what direction does the Maxillary prominence grow?

Answer 19

Medially. This pushes the nasal prominences closer together in the midline

Question 20

What does the nasal prominences fuse with?

Answer 20

Each other in the midline

The Maxillary prominences

Question 21

What does the Inter-maxillary segment give rise to?

Answer 21

The Primary palate

Question 22

What are the components of the Inter-maxillary segment?

Answer 22

Labial component (Philtrum)
Upper jaw (4 incisors)
Primary palate

Question 23

How is the Inter-maxillary segment created?

Answer 23

Fusion of the medial nasal prominences

Question 24

What is the main part of the definitive palate made of?

Answer 24

The secondary palate

Question 25

What is the secondary palate derived from?

Answer 25

Palatal shelves derived from the Maxillary prominence (2 made from the prominence)

Question 26

How do the Palatal shelves grow?

Answer 26

Downwards into the oral cavity either side of the developing tongue (Which drops when the Mandible grows larger) Palatal shelves then grow towards one another and fuse in the midline

Question 27

Where does the nasal septum (vomer) fuse?

Answer 27

It develops as a midline, growns downwards and fuses with the palatal shelves

Question 28

What is the dual origin of the lip and palate?

Answer 28

``` Intermaxillary segment (Philtrum and Primary palate) Maxillary process (Fused palatal shelves, lateral part of lip) ```

Question 29

What is the least severe version of a cleft lip disorder?

Answer 29

Lateral cleft lip

Question 30

What is a Lateral cleft lip?

Answer 30

Failure of fusion of the medial nasal prominence and maxillary prominence (Can involve the Primary palate)

Question 31

What is the most severe version of a cleft lip disorder?

Answer 31

A cleft lip and cleft palate

Question 32

What is a Cleft lip and cleft palate?

Answer 32

Failure of fusion of the medial nasal prominence and maxillary prominence AND Failure of the palatal shelves to meet in the midline

Question 33

What are some of the signs of a Cleft lip and cleft palate?

Answer 33

Cannot feed properly | Issues with speech development

Question 34

What does the Frontonasal prominence become?

Answer 34

Forehead Bridge of nose Medial nasal prominence Lateral nasal prominence

Question 35

What does the Medial nasal prominence become?

Answer 35

Philtrum Primary palate Mid upper jaw

Question 36

What does the Later nasal prominence become?

Answer 36

Sides of the nose

Question 37

What does the Maxillary prominence become?

Answer 37

Cheeks Lateral upper lip Secondary palate Lateral upper jaw

Question 38

What does the Mandibular prominence become?

Answer 38

Lower jaw Lower lip (The prominence begins relatively small, but then enlarges a lot)

Question 39

What is the primordia of the eyes?

Answer 39

Outpocketings of the forebrain on the side of the head (Optic vesicles)

Question 40

How do the Optic vesicles develop?

Answer 40

They grow outwards and make contact with the overlying ectoderm. They then grow out towards the surface to make contact with the Optic placodes

Question 41

What develops to make the lens of the eye?

Answer 41

Optic placodes

Question 42

What happens when the Optic vesicles meet the Optic placodes?

Answer 42

It invaginates and pinches off

Question 43

What are the Retinas derived from?

Answer 43

Optic vesicles

Question 44

Where are the eye primoridia originally placed?

Answer 44

At the side of the head

Question 45

Why do the eye primordia move?

Answer 45

The facial prominences grow which causes the eye primordia to move to their position during life

Question 46

What is the placode that aids auditory developed called?

Answer 46

The otic placode

Question 47

What does the external auditory meatus develop from?

Answer 47

The 1st Pharyngeal cleft

Question 48

What do the Auditory hillocks develop from?

Answer 48

The 1st Pharyngeal cleft. They go on to make the pinna of the ear from auricles

Question 49

Where do the ears initially develop?

Answer 49

Side of the neck

Question 50

How do the ears move to their normal position?

Answer 50

As the mandible grows the ears ascend to the side of the head and lie in line with the eyes

Question 51

What is Fetal alcohol syndrome?

Answer 51

The neural crest cells and development of the brain are very sensitive to alcohol. Usually occurs in pregnancies that have a large alcohol intake

Question 52

What are the signs of Fetal alcohol syndrome?

Answer 52

``` Low nasal bridge & short nose Small head Smooth Philtrum Thin upper lip Epicanthal folds Small eye openings ```

Question 53

How does the inner ear develop?

Answer 53

Otic placodes invaginate to form Auditory vesicles. | Makes the Membranous Labyrinth which will go on to develop into the Cochlea and Semi lunar canal system

Question 54

Where does the tongue develop?

Answer 54

Between the palatal shelves