Development of the Head and Neck 1 Flashcards Preview

ESA 4 - Head and Neck > Development of the Head and Neck 1 > Flashcards

Flashcards in Development of the Head and Neck 1 Deck (115):
1

What does the fetal skull have, that the adult skull doesn't? 

Fontanelles

2

What are fontanelles? 

Membranous areas of unfused skull 

3

When will the fontanelles be closed? 

Within the first 2 years of life 

4

What is the function of fontanelles? 

  • Flexibility allows passage through the birth canal 
  • Allow for brain growth

 

5

What changes in the fontanelles can indicate pathology? 

  • Sunken
  • Bulging 
  • Enlarged

 

6

What do sunken fontanelles indicate? 

Dehydration 

7

What do bulging fontanelles indicate? 

Increased intracranial pressure 

8

When do enlarged fontanelles often occur? 

In prematurity 

9

What is the problem with enlarged fontanelles? 

They can squash the brain, causing brain damage

10

When does the neural tube form?

Week 3 

11

How is the neural tube formed? 

  • The notocord is formed at gastrulation 
  • The notocord sends signals causing the overlying ectoderm to thicken
  • Edges of the ectoderm elevate out of slipper-shaped neural plate, out of the plane of the disc
  • Edges curl towards one another, creating neural tube

12

What happens to the anterior end of the neural tube? 

It begins to form the brain 

13

Describe the anterior end of the neural tube when it's beginning to form brain? 

Initially in 3 vesicle stage, and vesicles quickly specialise 

14

What do the vesicles of the neural tube specialise to form? 

  • Prosencephalon - forebrain
  • Mesencephalon - midbrain
  • Rhombencephalon - hindbrain

 

15

What has happened to the embryo by the end of week 4? 

It has folded 

16

What helps to fold the embryo? 

The growth of the neural tube

17

What does folding of the embryo create? 

Primitive gut tube 

18

Does the primitive gut tube include the primitive pharynx? 

Yes 

19

What is the primitive gut tube lined with? 

Endoderm 

20

Describe the head and neck region of the embryo early in week 4? 

  • Face has no distinguishing external features
  • Head and neck represent half the length of the embryo
  • There is an open pore in the neural tube cranially and caudally, which is fusing from the middle upwards

 

21

Where does the pharynx extend in the adult? 

From the base of the skull to the inferior border of the cricoid cartilage of the larynx

22

What are the divisions of the pharynx? 

  • Nasal 
  • Oral 
  • Laryngeal 

 

23

Where is the nasopharynx? 

Superior to the soft palate

24

Where is the oropharynx? 

Between the soft palate and the larynx 

25

Where is the laryngopharynx? 

Posterior to the larynx 

26

What are the pharyngeal (or brachial) arches? 

A system of mesenchymal proliferations in the neck region of the embryo

27

Where do the pharyngeal arches form? 

In the lateral walls of the embryonic pharynx, towards the cranial end of the neural tube

28

What gives the bumps of the pharyngeal arches? 

Lots of cell division and plastic mesenchyme production 

29

What are the pharyngeal arches involved in? 

Formation of the head and neck 

30

What type of tissues do the pharyngeal arches give rise to?

  • Muscles
  • Cartilages
  • Nerves
  • Arteries 

 

31

What systems of the body do the pharyngeal arches notably involve? 

  • Brain
  • CVS
  • Special sensory organs

 

32

What is the pharyngeal apparatus very closely associated to? 

Primitive heart and neural tube 

33

When are the pharyngeal arches apparent from? 

About 4 weeks in the developing embryo 

34

What does each arch have? 

Regarding its core

A large mesenchyme core

35

What migrates in to the mesenchyme core of the phayngeal arches? 

Some neural crest cells 

36

What are the pharyngeal arches covered in on either external surface? 

Ectoderm 

37

What is found between each arch on its external surface? 

Pharyngeal groove, or cleft 

38

What happens to the phayngeal groove? 

They eventually disappear, except the first (between the first and second arches) 

39

What does the first pharyngeal cleft become? 

The external auditory meatus of the ear 

40

What forms around the entrance to the external auditory meatus? 

Swellings

41

What forms from the swellings of the entrance to the meatus? 

The external ear (auricle) 

42

How do the clefts disappear? 

The second cleft grows down to cover the others, obliterating all the other clefts 

43

What happens if the cervical sinus is not obliterated? 

Cysts or fistulae can occur

44

Where can cysts or fistulae resulting from failure of obliteration of cervical sinus occur? 

Anywhere along the anterior border of the sternocleidomastoid

45

What is the internal surface of the pharyngeal arch? 

The part facing into the primitive gut tube

46

What is the internal surface of each pharyngeal arch covered by? 

Endoderm 

47

What is formed by the internal surface of the pharyngeal arch? 

A similar pattern of grooves between each arch, known as pharyngeal pouches 

48

What arises from the pharyngeal pouches? 

  • Parathyroid
  • Thymus
  • Tonsils
  • Middle ear 

 

49

What are the pharyngeal arches, grooves, and pouches collectively known as? 

Pharyngeal apparatus 

50

How many pharyngeal arches are there? 

5, numbered 1-6 

The 5th arch doesn't form in humans 

51

Which pharyngeal arch is biggest? 

1st 

52

What happens to the size of the phayngeal arches? 

They get progessively smaller from 1 to 6, so the 4th and 6th arch are not as readily visible as the others

53

What is associated with each pharyngeal arch? 

  • Cartilage bar 
  • Nerve
  • Artery

 

54

What is the cartilage bar of each pharyngeal arch dervied from? 

Neural crest cells 

55

What will the cartilage bars subsequently become? 

Skeletal elements of head and neck 

56

Which cartilaginous bar is largest? 

Cartilage bar of 1st pharyngeal arch 

57

What does the cartilage bar of the first pharyngeal arch do? 

Divides into maxillary and mandibular prominences 

58

What is the mandibular prominence known as? 

Meckel's cartilage

59

What does Meckels cartilage give rise to? 

  • Malleus
  • Incus

 

60

How to the malleus and incus arise from the Meckel's cartilage? 

Remodelling 

61

What does the mandibular prominence provide? 

Template for mandible 

62

How does the mandible form from the mandibular prominence? 

Membranous ossification 

63

What is the cartilage bar of the 2nd arch known as? 

Reichert's 

64

What does the cartilage bar of the 4th and 6th arch give rise to? 

  • Thyroid
  • Arytenoids
  • Cricoids

 

65

What are the ossicles of the middle ear derived from? 

Cartilage bar 

66

How many pairs of cranial nerves are there? 

12

67

What happens to the cranial nerves during development? 

They loose their segemental arrangement 

68

How are the cranial nerves classified? 

Based on their function and their embryological origin 

69

What are the classifications of cranial nerves?

  • Somatic efferent
  • Special sensory
  • Nerves of pharyngeal arches 

 

70

What parts of the neural tube are the cranial nerves derived from? 

The mid- or hind-brain, except CN I and II 

71

What cranial nerves are associated with the pharyngeal arches?

V, VII, IX, and X

72

Where do the cranial nerves associated with the pharyngeal arches arise from? 

The lowest part of the brainstem

73

What do the cranial nerves associated with the pharyngeal arches innervate? 

They innervate the pharyngeal arch, and therefore the structural derivates of each pharyngeal arch is innervated by the particular cranial nerve associated with that arch 

74

What cranial nerve is associated with the first pharyngeal arch? 

Trigeminal (V)

 

75

What cranial nerve is associated with the second pharyngeal arch? 

Facial (VII)

76

What cranial nerve is associated with the 3rd pharyngeal arch? 

Glossopharyngeal (IX)

77

What cranial nerve is associated with the 4th pharyngeal arch? 

Vagus (X)

78

What cranial nerve is associated with the 6th pharyngeal arch? 

Vagus (X)

79

What cranial nerves have a relationship wtih the pharyngeal arch system? 

  • CN XI (cranial accessory)
  • CN XII 

 

80

Where does the aortic sac lie?

On the floor of the pharynx

81

What does each pharyngeal arch become associated with? 

Regarding blood vessels

An aortic arch of blood vessels 

82

What does each aortic arch blood vessel run through?

The mesenchyme of its respective pharyngeal arch

83

How does the arrangement of the aortic arch blood vessels initially appear? 

Very organised 

84

What happens to the arrangement of the aortic arch blood vessels? 

As the embryo develops, and structures start to derive from the pharyngeal arches, much of the order is lost 

85

What is the rearrangement of developing structures the reason for? 

The recurrent laryngeal nerve of the vagus becomes looped under the arch of the aorta on the left side, and the subclavian artery on the right side

86

What artery is derived from the first arch? 

Common, external, and internal carotid arteries and branches 

87

What artery is derived from the second arch? 

Common, external, and internal carotid arteries and branches

88

What artery is derived from the third arch? 

Common, external, and internal carotid arteries and branches 

89

What artery is derived from the forth arch? 

Aortic arch (on left) and subclavian artery (on right) 

90

What artery is derived from the sixth arch? 

Pulmonary arteries 

91

What are the muscular derivatives of the first arch? 

  • Muscles of mastication
  • Mylohyoid
  • Anterior belly of digastric
  • Tensor tympani
  • Tensor veli palatine

92

What are the muscular derivates of the second arch? 

  • Muscles of facial expression
  • Stapedius
  • Stylohyoid
  • Posterior belly of digastric

93

What are the muscular derivates of the third arch? 

Stylopharyngeus (muscle of the pharynx)

94

What are the muscular derivates of the fourth arch? 

  • Cricothyroid
  • Levator palatine
  • Constrictors of pharynx

95

What are the muscular derivates of the sixth arch? 

Intrinsic muscles of the larynx

96

What are the sensory derivatives of the first arch? 

Main sensory supply to the face and nasopharynx

97

What are the sensory derivatives of the 2nd arch? 

Special sensory (taste) to anterior 2/3 of tongue 

98

What are the sensory derivates of the 3rd arch? 

Sensory to posterior 1/3 of the tongue, and upper part of the pharynx

99

What are the sensory derivatives of the 4th and 6th arches? 

Sensory to linings of the lower pharynx and all larynx

100

What are the skeletal derivative of the first arch? 

  • Maxillae and zygomatic bones 
  • Meckel's cartilage
    • Malleus
    • Incus
  • Mandible 

 

101

What are the skeletal derivates of the second arch? 

Reichert's cartilage; 

  • Hyoid
    • Lesser cornu 
    • Upper body
  • Stapes
    • Part of middle ear
  • Styloid process
  • Stylohyoid ligament

 

102

What are the skeletal derivatives of the 3rd and 4th arch? 

Epiglottis

103

What are the skeletal derivatives of the 4th and 6th arches? 

Cartilages of larynx

104

What does the facial skeleton arise from? 

The frontonasal prominence and the first pharyngeal arch 

105

Why do the muscles of facial expression and the muscles of mastication have different cranial nerve innervation, despite being so topographically related

Due to them being derived from different pharyngeal arches 

106

What are the muscles of mastication derived from? 

The first pharyngeal arch 

107

What is the result of the muscles of mastication being derived from the first pharyngeal arch? 

They are innervated by the facial nerve (CN VII) 

108

What is CN VII the nerve of? 

The second arch 

109

What does CN VII pass through?

The stylomastoid foramen and parotid gland 

110

What happens in the second pharyngeal pounch? 

There is epithelial proliferation, followed by migration in and colonisation by lymphoid precursors 

111

What happens to the 3rd and 4th pharyngeal pouches? 

They divide into dorsal and ventral components 

112

What are the derivatives of the first pharyngeal pounch? 

  • Pharyngotympanic (Eustachian) tube
  • Middle ear cavity

 

113

What are the derivatives of the second phayngeal pouch? 

Palatine tonsil 

114

What are the derivatives of the third pharyngeal pouch? 

  • Inferior parathyroid (dorsal) 
  • Thymus (dorsal and ventral) 

 

115

What are the derivatives of the 4th pharyngeal pouch? 

  • Superior parathyroid
  • C cells of thyroid