embryology of head and neck Flashcards

1
Q

when does the face form

A

weeks 4-14

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2
Q

when does the thyroid, thymus and parathyroid form

A

weeks 4-7

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3
Q

what are the bones around the brain called

A

the neurocranium (8 bones)

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4
Q

what are the facial bones called

A

the viscerocranium (15 bones)

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5
Q

what are the flat bones of the neurocranium and what is this group called

A

frontal and parietal bones
calvaria

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6
Q

what are the bones of neurocranium that make up the base of the skull

A

the chondrocranium

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7
Q

what is the cellular origin of the facial bones and frontal bone

A

neural crest cells from the dorsal part of neural tube

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8
Q

what is the cellular origin of the skull bones (minus the frontal)

A

the paraxial mesoderm, cells that are cranial to the somites
called: unsegmented, somitic, somitomeric or pre-otic

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9
Q

what is the cellular origin of the laryngeal bones

A

the lateral plate mesoderm

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10
Q

what is endochondral ossification

A

formation of a cartilage template and then formation of bone

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11
Q

what is intramembranous ossification

A

direct formation of bone

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12
Q

what skull bones form via endochondral ossification

A

occipital bone (chondrocranium)

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13
Q

what skull bones form via intramembranous ossification

A

the parietal and frontal bones

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14
Q

what are sutures important for

A

molding at birth

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15
Q

where do sutures arise from

A

sagital: neural crest
coronal: paraxial mesoderm

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16
Q

When do the anterior and mastoid fontanelles close?

A

around 2 years

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17
Q

when do the posterior and sphenoidal fontanelles close

A

after 6 months

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18
Q

what is craniosynostosis

A

premature fusion of sutures

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19
Q

scaphocephaly is what

A

a long AP skull due to early fusion of sagittal suture

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20
Q

bradycephaly is what

A

a short square shaped skull due to early coronal fusion

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21
Q

Crouzon syndrome

A

AD
FGFR2 gain of function mutation
craniosynostosis, ocular proptosis, mandibular prognathism, progressive hydrocephaly

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22
Q

Apert syndrome

A

AD
FGFR2 gain of function mutation
craniosynostosis, syndactyly of hands and feet, mental retardation

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23
Q

Pfeiffer syndrome

A

AD
FGFR2 gain of function mutation
craniosynostosis, syndactly of hands and feet

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24
Q

when do pharyngeal arches form

A

in the 4th week

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25
Q

what are pharyngeal pouches

A

evaginations of the endoderm between arches

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26
Q

what are pharyngeal clefts

A

invaginations of ectoderm between arches

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27
Q

how many arches, pouches and clefts

A

5 arches, 4 pouches and clefts

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28
Q

what does each arch contain

A

cartilage, muscles, artery and nerve

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29
Q

where does the muscle of pharyngeal arches come from

A

somitic mesoderm

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30
Q

where does the artery of pharyngeal arches come from

A

somitic mesoderm

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31
Q

where does the cartilage of pharyngeal arches come from

A

lateral plate neural crest cells

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32
Q

where does the nerve of pharyngeal arches come from

A

neural tube (ectoderm)

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33
Q

how does the mandible form

A

intramembranous ossification

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34
Q

what is and does meckels cartilage form

A

It is the first pharyngeal arch
the mandible, incus and malleus

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35
Q

what is and does Reicherts cartilage form

A

It is the 2nd pharyngeal arch
the lesser horn of hyoid, styloid process, stapes

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36
Q

what does the 3rd pharyngeal arch form

A

the greater horn of hyoid bone

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37
Q

what is the origin of the 1, 2 and 3rd pharyngeal arches

A

the neural crest cells

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38
Q

what is the origin of the IV and VI pharyngeal arches

A

lateral plate mesoderm

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39
Q

what do the 4th and 6th pharyngeal arches form

A

thyroid cartilage, cricoid cartilage and arytenoid cartilage

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40
Q

what nerve innervates the 1st arch

A

trigeminal nerve (CN V)

41
Q

what nerve innervates the 2nd arch

A

facial nerve (CN VII)

42
Q

What nerve innervates the 3rd arch

A

glossopharyngeal nerve (CN IX)

43
Q

what nerve innervates the 4th and 6th arch

A

the superior laryngeal branch and the recurrent branch of the vagus (CN X)

44
Q

what does cleft 1 form

A

the external auditory meatus and the external part of the tympanic membrane

45
Q

what forms the cervical sinus

A

cleft 2 migrates and 3 and 4 curl up

46
Q

what does pouch 1 form

A

the tubotympanic recess that becomes the Eustachian tubes

47
Q

what does pouch 4 form

A

the ultimobranchial body and superior paraythyroid

48
Q

what does pouch 2 form

A

the tonsil

49
Q

what does pouch 3 form

A

the inferior parathyroid and the thymus

50
Q

when is the thymus active

A

during perinatal period and childhood and then involutes after puberty

51
Q

what does PTH do

A

increases Ca2+ levels in the blood

52
Q

where is the thyroid gland derived from

A

not from a pouch
from the floor of pharynx between pouch 1 and 2 (endoderm)

53
Q

what are the hypoglossal ducts

A

they connect the foramen cecum to the thyroid gland

54
Q

when does thyroid function begin

A

week 10-12

55
Q

what does the ultimobranchial body do

A

fuses with thyroid gland and creates calcitonin producing ‘C’ cells

56
Q

what is the derivative of C cells

A

endoderm

57
Q

what does calcitonin do

A

reduces calcium levels in the blood

58
Q

first arch syndromes

A

insufficient migration of neural crest cells into pharyngeal arch 1
- treacher-collin syndrome
- Pierre robin syndrome

59
Q

treacher collins syndrome

A

AD
TCOF1 gene mutation, treacle protein mutation
causes: hypoplasia of mandible, external ear abnormalities

60
Q

Pierre robin syndrome

A

SOX9 gene associated
u shaped cleft palate, glossoptosis and airway obstruction

61
Q

DiGeorge syndrome cause

A

failure of pouches 3 and 4 to differentiate into thymus and parathyroid glands
- micro deletion of chromosome q22
- abnormal neural crest migration

62
Q

DiGeorge syndrome symptoms

A

facial anomalies
immunosuppression (thymus)
hypocalcemia (parathyroid)

63
Q

Pharyngeal fistula

A

persistence of pouch 2 or cleft 2
anterior border of SCM

64
Q

pharyngeal cyst

A

persistence of clefts 2, 3, 4
along angle of mandible
drainage in palatine tonsil

65
Q

thyroglossal cysts and sinuses

A

if the thyroglossal duct persists and forms a cyst
- located in midline near hyoid

66
Q

thyroglossal cyst under the tongue

A

lingual cyst

67
Q

derivative of frontal nasal prominance

A

forehead, dorsal and apex of nose

68
Q

derivative of lateral nasal prominance

A

alae (sides) of nose

69
Q

derivative of medial nasal prominance

A

nasal septum, ethmoid bone, cribriform plate

70
Q

derivative of intermaxillary segment

A

philtrum and primary plate

71
Q

derivative of maxillary prominance

A

upper cheek region and lip

72
Q

derivative of mandibular prominance

A

chin, lower lip and cheek

73
Q

derivative of fusion of Fr. nasal and max pr

A

nasolacrimal duct

74
Q

what is the name of the opening form the nasal cavity to the mouth

A

choana

75
Q

how does that hard palate form

A

intramembranous ossification

76
Q

what is in the soft palate

A

muscles
vagus and trigeminal nerves

77
Q

what is choanal atresia

A

cyclical period of cyanosis due to a closed choana

78
Q

the anterior 2/3 of the tongue is formed by what

A

the first arch

79
Q

the posterior 1/3 of the tongue is formed by the what

A

the third arch

80
Q

what forms the epiglottis

A

the 4th arch

81
Q

what is ankyloglossia

A

tongue tied

82
Q

innervation of anterior 2/3 of tongue

A

trigeminal ganglion

83
Q

innervation of taste buds

A

facial nerve

84
Q

innervation of posterior tongue and epiglottis

A

vagus nerve

85
Q

innervation of posterior 1/3 of tongue and vallate apillae

A

glossopharyngeal nerves

86
Q

tongue musculature innervation

A

hypoglossal nerve cranial nerve XII

87
Q

what is the dental papilla

A

a transient signalling structure that signals to form the enamel knot

88
Q

precursor of enamel

A

ameloblasts

89
Q

precursor of predentin

A

odontoblasts

90
Q

morphogen means

A

dose dependent signalling

91
Q

defect resulting in loss of Shh defects

A

severe midline defects

92
Q

low Shh activity

A

cyclopia

93
Q

very high Shh activity

A

facial duplications

94
Q

holoprosencephaly

A

cyclopia

95
Q

what is the cause of cleft lip

A

failure of maxillary prominance and medial nasal prominance joining

96
Q

cleft palate cause

A

failure of palatal shelves (primary and secondary) fusing together along midline

97
Q

cleft lip is where in relation to incisive foramen

A

anterior

98
Q

cleft palate is where in relation to incisive foramen

A

posterior

99
Q

clefts distribution among sexes

A

lip more common in men
palate more common in females