Head & Neck Embryology Flashcards

1
Q

What are the components of the pharyngeal (brachial) apparatus?

A
  • Pharyngeal arch
  • Pharyngeal groove (clef)
  • Pharyngeal pouch
  • Pharyngeal membrane
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2
Q

What cells are found in pharyngeal arches?

A

Neural crest cells

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3
Q

Initially, pharyngeal arches are a core of ___ covered by ______

A

Initially, pharyngeal arches are a core of mesenchyme covered by ectoderm externally and endoderm internally

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4
Q

What are the components of each pharyngeal arch?

A
  • Artery
  • Bone (cartilaginous rod)
  • Muscle
  • Nerve
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5
Q

The artery of a pharyngeal arch is derived from…

A

truncus arteriosus

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6
Q

Do pharyngeal arches 1, 2, and 3 develop together or separately?

A

Separately

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7
Q

Cartilaginous portions of which pharyngeal arches will fuse?

A

Arches 4 and 6

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8
Q

Which pharyngeal arch regresses and has no derivatives?

A

Arch 5

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9
Q

What is included in the frontonasal prominence?

A
  • Optic vesicles
  • Forehead
  • Stomodeum (primordial mouth)
  • Nose (frontal and lateral nasal prominences)
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10
Q

The first pharyngeal arch is also known as…

A

mandibular arch

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11
Q

What is the bone/cartilage component of the first pharyngeal arch?

A

Meckel’s cartilage

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12
Q

first arch

The maxillary prominence and mandibular prominence are from mesoderm around…

A

Meckel’s cartilage

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13
Q

first arch

What will come of the maxillary prominence?

A
  • Maxilla
  • Zygomatic bone
  • Squamous part of temporal bone
  • Upper cheek regions and lip
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14
Q

first arch

What will come of the mandibular prominence?

A
  • Mandible
  • Chin, lower lip, cheek regions
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15
Q

first arch

What will come of the dorsal end?

A
  • Malleus
  • Incus
  • Sphenomandibular ligament
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16
Q

What are five muscular components of the first pharyngeal arch?

A
  • Muscles of mastication
  • Tensor veli palatini
  • Tensor tympani
  • Mylohyoid
  • Anterior belly of digastric
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17
Q

What is the nerve component of the first pharyngeal arch?

A

CN V trigeminal

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18
Q

The second pharyngeal arch is also known as…

A

hyoid arch

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19
Q

What is the bone/cartilage component of the second pharyngeal arch?

A

Reichert’s cartilage

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20
Q

second arch

What will come of Reichert’s cartilage?

A
  • Stapes
  • Styloid process
  • Stylohyoid ligament
  • Lesser cornu and upper part of body of hyoid
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21
Q

What are four muscular components of the second pharyngeal arch?

A
  • Muscles of facial expression
  • Stapedius
  • Stylohyoid
  • Posterior belly of digastric
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22
Q

What is the nerve component of the second pharyngeal arch?

A

CN VII facial

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23
Q

What would you call a persistent second pharyngeal groove or cervical sinus?

A

Branchial cyst

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24
Q

When is a branchial cyst apparent?

A

Beginning in late childhood or early adulthood

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25
Q

How does a branchial cyst appear?

A

Painless swollen mass slowly enlarging inferior to angle of mandible and anterior to SCM

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26
Q

Which pharyngeal arch does not develop into adult structures?

A

Arch 5

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27
Q

What are the bone/cartilage components of the third pharyngeal arch?

A
  • Thyroid cartilage
  • Hyoid bone (greater cornu and part of body)
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28
Q

What is the muscular component of the third pharyngeal arch?

A

Stylopharyngeus

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29
Q

What is the nerve component of the third pharyngeal arch?

A

CN IX glossopharyngeal

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30
Q

What is the bone/cartilage component of the fourth and sixth pharyngeal arches?

A

Laryngeal cartilages (except epiglottis)

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31
Q

The epiglottis develops from…

A

hypopharyngeal eminence

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32
Q

What is the muscular component of the fourth and sixth pharyngeal arches?

A

Pharyngeal and laryngeal muscles:

  • Cricothyroid
  • Levator veli palatini
  • Pharyngeal constrictor muscles
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33
Q

What is the nerve component of the fourth and sixth pharyngeal arches?

A

CN X vagus
4: superior laryngeal nerve
6: recurrent laryngeal nerve

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34
Q

The tympanic cavity, mastoid antrum, pharyngotympanic tube, and tympanic membrane are all derived from which pharyngeal apparatus pouch?

A

First pouch

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35
Q

The tonsillar fossa and palatine tonsils are derived from which pharyngeal apparatus pouch?

A

Second pouch

36
Q

The inferior parathyroid glands and thymus are derived from which pharyngeal apparatus pouch?

A

Third pouch

37
Q

The superior parathyroid glands and thyroid parafollicular cells are derived from which pharyngeal apparatus pouch?

A

Fourth pouch

38
Q

thyroid parafollicular cells

C-cells produce…

A

calcitonin

39
Q

What comes of the pharyngeal apparatus first groove?

A

External auditory meatus

40
Q

What comes of the pharyngeal apparatus grooves (besides the first)?

A

Lie in cervical sinus and are obliterated as neck develops or becomes branchial cyst

41
Q

What happens to the pharyngeal apparatus grooves if they are not obliterated as the neck develops?

A

Branchial cyst

42
Q

When is the tongue developed in utero?

A

End of week 4

43
Q

In the development of the tongue, the first pharyngeal arch gives rise to…

A

median and lateral lingual swellings

44
Q

The rostral tongue develops from…

A

hypopharyngeal eminence

45
Q

Hypopharyngeal eminence (thus rostral tongue) is derivative of…

A

fourth pharyngeal arch

46
Q

Rostral tongue is ___ to sulcus terminalis

A

posterior

47
Q

What is the innervation of the tongue during development?

A

CN XII hypoglossal

48
Q

When do taste buds develop in utero?

A

Weeks 11-13

49
Q

When is primary growth of the face in utero?

A

Weeks 4-8

50
Q

The frontonasal prominence includes…

A
  • optic vesicles
  • forehead
  • stomodeum
  • nose
51
Q

The maxillary prominences include…

A
  • lateral boundaries of stomodeum
  • upper cheek regions and lip
52
Q

The mandibular prominences include…

A
  • caudal boundary of stomodeum
  • chin, lower lip, and cheek regions
53
Q

Which pharyngeal arch will develop into muscles of facial expression?

A

Second pharyngeal arch

54
Q

When do primordial auricles begin developing in utero?

A

End of week 5: 3 bilateral pairs of auricular hillocks from near first pharyngeal groove

55
Q

How do the ears shift at the end of week 5 in utero?

A

Ears migrate up from neck region as mandible develops

56
Q

When do maxillary and lateral nasal prominences begin fusion at nasolacrimal duct in utero?

A

End of week 6

57
Q

When does oronasal membrane rupture in utero?

A

End of week 6

58
Q

When will conchae and olfactory epithelium develop in utero?

A

By week 12

59
Q

How do air sinuses of the face develop?

A
  • Maxillary sinuses: fetal development
  • Other air sinuses: after birth
60
Q

What is the cause of a chin dimple?

A

Incomplete fusion of left and right mandibular prominences

61
Q

The development of palate begins…

A

week 6 in utero

62
Q

What is the primary palate in development?

A

Premaxillary part of maxillae

63
Q

What is the secondary palate in development?

A

Lateral palatine processes (palatine shelf)

64
Q

How common is a cleft lip?
Who is more likely to have a cleft lip?

A

1 in 1000 births
males > females (60-80% males)

65
Q

How common is a cleft palate?
Who is more likely to have a cleft palate?

A

1 in 2500 births
females > males

66
Q

Optic vesicles project from…

A

forebrain

67
Q

Optic vesicles invaginate to form…

A

optic cups

68
Q

Optic cups develop into…

A

retina and ciliary body

69
Q

Surface ectoderm of the eye forms…

A

lens placode

70
Q

Lens placode develops into…

A

lens

71
Q

Surface ectoderm of the ear thickens into…

A

otic placode

72
Q

Otic placode invaginates to form…

A

otic pit

73
Q

The edges of the otic pit fuse to form…

A

otic vesicle which forms inner ear

74
Q

The middle ear (ossicles and auditory tube) develop from which parts of the pharyngeal apparatus?

A

First and second arches

75
Q

The external ear develops from which parts of the pharyngeal apparatus?

A

First and second arches, and first pharyngeal groove

76
Q

What is the first endocrine gland to develop?

A

Thyroid gland

77
Q

Thyroid primordium can be found…

A

on back of tongue/pharynx

78
Q

The thyroid primordium descends to neck through…

A

thyroglossal duct

79
Q

When will the thyroid primordium descend to the neck in utero?

A

24 days

80
Q

When will the thyroid gland assume adult shape and reach the final site in anterior midline of neck?

A

By week 7 in utero

81
Q

When will the thyroglossal duct degenerate in utero?

A

By week 7

82
Q

In an adult, proximal opening of thyroglossal duct persists as…

A

foramen cecum on tongue

83
Q

How does a persistent thyroglossal duct appear in an adult?

A

Round firm mass (swelling) in median plane of neck inferior to hyoid bone

84
Q

A patient is born without a thymus gland and inferior parathyroid glands
Which portion of the pharyngeal apparatus is involved in this defect?

A

Third pharyngeal pouch

85
Q

Treacher-Collins syndrome is characterized by malformed or absent ears, zygomatic and mandibular hypoplasia, and downward slanted eyes
This condition involves which pharyngeal arch?

A

First pharyngeal arch

86
Q

A patient notices asymmetry in her neck when she tenses the skin of her inferior face and neck; she is lacking a platysma on one side of her neck
This asymmetry involves which pharyngeal arch?

A

Fourth and sixth pharyngeal arches