Development of the Face Flashcards Preview

ESA 4 - Head and Neck > Development of the Face > Flashcards

Flashcards in Development of the Face Deck (70):
1

What is the first evidence of the development of the face? 

The appearance of the stomadaeum 

2

What is the stomadaeum? 

A depression in the ectoderm on the ventral aspect of the head

3

What is the stomadauem the site of? 

The future mouth 

4

How is the stomodeum seperated from the anterior end of the foregut? 

By the buccopharyngeal membrane

5

Describe the ectoderm, mesoderm, and endoderm arrangement at the buccopharyngeal membrane? 

No mesoderm between ectoderm/endoderm 

6

What form around the stomadauem? 

Five folds (prominences/processes)

7

What are the prominences/processes that form around the stomadauem?

  • Frontonasal prominence
  • Maxillary prominences (2)
  • Mandibular prominences (2)

 

8

Where does the frontonsal prominence form? 

Superiorly, in the midline 

9

What does the frontonasal prominence form? 

  • Forehead
  • Bridge of nose
  • Upper eyelids
  • Centre of upper lip 

 

10

Where are the maxillary prominences? 

Laterally 

11

What are the maxillary prominences derived from? 

The 1st pharyngeal arch 

12

What do the maxillary prominences form? 

  • Middle third of face
  • Upper jaw
  • Most of the lip
  • Sides of the nose

 

13

Where are the mandibular prominences? 

Inferolaterally 

14

What are the mandibular prominences derived from? 

The 1st pharyngeal arch 

15

What do the mandibular prominences form?

  • Lower 1/3 of the face
  • Lower jaw
  • Lip

 

16

What do the facial prominences consist of? 

Mesenchyme with a covering of ectoderm 

17

What will eventually happen to the facial prominences? 

They will fuse together to complete the face 

18

What results from the failure of fusion of the facial prominences?

Facial clefts and cleft lip

19

What is the first evidence of nose formation? 

The apperance of bilateral ectodermal thickenings, the nasal placodes

20

Where do the nasal placodes first appear? 

On the venterolateral aspect of the frontonasal prominence

21

What happens to the nasal placodes?

They invaginate to form the nasal pits 

22

What is the entrance of each nasal pit?

The nostril

23

What forms around the entrance to each nostril? 

A horse-shoe shaped ring 

24

What are the 'arms' of the horseshoe around the nostril? 

The medial and lateral nasal prominences 

25

Where do the deepening nasal pits lie? 

Dorsal to the stomodaeum 

26

What seperates the nasal pits? 

A thin sheet of cells, the oronasal membrane 

27

What happens to the oronasal membrane? 

It disappears, and the oral and nasal cavities become one continuous space 

28

In what direction does the maxillary prominence grow? 

Medially 

29

What happens when the maxillary prominences grow medially? 

They push the nasal prominences closer together in the midline 

30

What do the maxillary prominences fuse with? 

The medial nasal prominences 

31

Where do the medial nasal prominences fuse? 

In the midlien 

32

What does the seperation of the oral and nasal cavity require? 

The development of the palate 

33

What does the development of the palate involve? 

Both the maxillary and medial nasal prominences 

34

What happens when the medial nasal prominences fuse in the midline? 

It seperates the nostrils from the mouth

35

What does the seperation of the nostrils from the mouth by the fusion of the medial nasal prominences give rise to? 

  • Philtrum of the upper limb (groove)
  • Median part of the maxillary bone, with itrs four incisor teeth
  • Primary palate (or premaxillary portion)

 

36

What is the primary palate? 

A small midline component of the palate 

37

What grows from each maxillary prominence? 

A palatal shelf 

38

In what direction does the palatal shelf grow? 

Towards the midline 

39

What happens to the palatal shelves?

They fuse with each other, and with the primary palate 

40

What creates the secondary palate?

Fusion 

41

What does the secondary palate do? 

Seperates the nasal cavity from the oral cavity 

42

What does the mandible need to grow large enough to do? 

Allow the tongue to 'drop' out of the way, allowing the fusion of the palatal shelves

43

How does the nasal septum develop? 

As a midline down-growth 

44

What ultimately happens to the nasal septum? 

It fuses with the palatal shelves 

45

What does a cleft palate result from? 

Failure of one or both of the palatal shelves to reach the midline and fuse with its counterpart 

 

 

46

What does a lateral cleft lip result from? 

Failure of fusion of the medial nasal prominence and maxillary prominence

47

What is a cleft lip combined with in a cleft palate? 

Failure of platal shelves to meet in midline 

48

When does the development of the eyes begin? 

In the 4th week 

49

How does the development of the eyes begin? 

With out-pockets of the forebrain 

50

What happens to the out-pockets of the forebrain in development of the eyes? 

They grow to make contact with the overlying ectoderm,

51

What does the contact between the out-pockets of the brain and the overlying ectoderm cause? 

Changes in the ectoderm that form the optic placodes

52

What do the optic placodes become? 

The lens of the eyes 

53

What happens to the optic/lens placodes do after formation? 

Invaginate and pinch off

54

When do eyelids begin to develop?

At the end of the embryonic period (week 8)

55

Describe the developmental programme of the eyelids

They are fused together during the second trimester, and reopen in the third

56

Where are the primordia of the eyes positioned? 

On the side of the head 

57

What happens to the eyes as the facial prominences grow? 

The eyes move to the front of the face 

58

What does the external auditory meatus develop from? 

The 1st pharyngeal cleft 

59

What do the auricles develop from? 

Within and 1st and 2nd pharyngeal arch 

60

Which auricles develop from the 1st pharyngeal arch? 

  • Malleus
  • Incus

 

61

What develops from the 2nd pharyngeal arch? 

Stapes 

62

What are the otic placodes made from? 

Ectoderm that thickens before sinking 

63

What happens when the otic placodes invaginate? 

They form the auditory vesicles 

64

Where do the external ears intially develop?

In the neck

65

What happens to the ears as the mandible grows?

The ears ascend to the side of the head to lie in line with the eyes 

66

What common chromosomal abnormalities have associated external ear abnormalities? 

All 

67

What does alcohol during pregnany cause? 

Classic facial symptoms; 

  • Small eye/nose opening
  • Thin Philtrum
  • Under-developed jaw

 

68

What is the safe level of alcohol consumption during pregnancy?

No known safe level 

69

What organs development is known to be sensitive to alcohol? 

The brain 

70

What is pathology of the brain related to alcohol during pregnancy traced back to? 

Migration of neural crest cells