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Flashcards in Session 3 Deck (54):
1

Define Neural crest

A specialised population of cells that
originates within the neurectoderm

2

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

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

3

What are the major features of the face?

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

4

Where do the Pharyngeal arches develop?

In the neck region around the Aortic arches

5

What does each Pharyngeal arch have?

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

6

What forms the facial skeleton?

Neural crest of 1st Pharyngeal arch

7

What forms the muscles of mastication?

Mesoderm of 1st Pharyngeal arch

8

What forms the muscles of facial expression?

Mesoderm of 2nd Pharyngeal arch (First prominence)

9

What is the facial primordia made of?

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

10

Why is the Frontonasal prominence large?

Because it surrounds the ventro-lateral part of the forebrain

11

What drives development of the face?

Expansion of the cranial neural tube

12

What is the Stomatodeum?

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

13

What does the 1st Pharyngeal arch develop into?

Maxillary prominence
Mandibular prominence

14

What are the derivatives of the Frontonasal prominence?

Forehead
Bridge of nose
Nose
Philtrum

15

What are the derivatives of the Maxillary prominence?

Cheeks
Lateral upper lip
Lateral upper jaw

16

What are the derivatives of the Mandibular prominence?

Low lip
Jaw

17

What is a placode?

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

18

Where do the nasal placodes appear?

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

19

In what direction does the Maxillary prominence grow?

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

20

What does the nasal prominences fuse with?

Each other in the midline
The Maxillary prominences

21

What does the Inter-maxillary segment give rise to?

The Primary palate

22

What are the components of the Inter-maxillary segment?

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

23

How is the Inter-maxillary segment created?

Fusion of the medial nasal prominences

24

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

The secondary palate

25

What is the secondary palate derived from?

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

26

How do the Palatal shelves grow?

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

27

Where does the nasal septum (vomer) fuse?

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

28

What is the dual origin of the lip and palate?

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

29

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

Lateral cleft lip

30

What is a Lateral cleft lip?

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

31

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

A cleft lip and cleft palate

32

What is a Cleft lip and cleft palate?

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

33

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

Cannot feed properly
Issues with speech development

34

What does the Frontonasal prominence become?

Forehead
Bridge of nose
Medial nasal prominence
Lateral nasal prominence

35

What does the Medial nasal prominence become?

Philtrum
Primary palate
Mid upper jaw

36

What does the Later nasal prominence become?

Sides of the nose

37

What does the Maxillary prominence become?

Cheeks
Lateral upper lip
Secondary palate
Lateral upper jaw

38

What does the Mandibular prominence become?

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

39

What is the primordia of the eyes?

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

40

How do the Optic vesicles develop?

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

41

What develops to make the lens of the eye?

Optic placodes

42

What happens when the Optic vesicles meet the Optic placodes?

It invaginates and pinches off

43

What are the Retinas derived from?

Optic vesicles

44

Where are the eye primoridia originally placed?

At the side of the head

45

Why do the eye primordia move?

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

46

What is the placode that aids auditory developed called?

The otic placode

47

What does the external auditory meatus develop from?

The 1st Pharyngeal cleft

48

What do the Auditory hillocks develop from?

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

49

Where do the ears initially develop?

Side of the neck

50

How do the ears move to their normal position?

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

51

What is Fetal alcohol syndrome?

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

52

What are the signs of Fetal alcohol syndrome?

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

53

How does the inner ear develop?

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

54

Where does the tongue develop?

Between the palatal shelves