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NS-1 > Development of Orofacial Structures > Flashcards

Development of Orofacial Structures Flashcards

1
Q

What is intramembranous ossification?

A

mesenchyme condenses –> osteoblasts –> osteocytes

*no cartilage in btw

*flat bones

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2
Q

what is endochondral ossification?

A

bone formation occurs in preexisting cartilagious models

long bones

primary ossification in diaphysis

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3
Q

What is the neurocranium?

A

bony case that encloses the brain

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4
Q

What is the viscerocranium?

A

bones comprising the facial skeleton

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5
Q

What is the cartilaginous neurocranium and its development?

A

endochondral ossification: several cartilages fuse –> base of cranium

occipital bone –> body of sphenoid –> ethmoid

temporal bone (petrous and mastoid parts)

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6
Q

What are the membranous parts of the neurocranium?

A

calvaria = frontal and parietal bones

(intramembranous ossification)

interconnected via sutures

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7
Q

What forms the cartilage of the cartilaginous neurocranium?

A

NCCs from midbrain

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8
Q

What are the structures derived from cartilaginous viscerocranium?

A

PA structures –>

ossicles

styloid process of temporal b

horns of hyoid

laryngeal cartilages (except epiglottis

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9
Q

What germ layer forms the cartilaginous viscerocranium?

A

NC from hindbrain

*except base of stapes = mesoderm

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10
Q

What is distinct about the squamous part of the temporal bone?

A

initially part of membranous viscerocranium –> becomes part of the neurocranium

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11
Q

What are the parts of the membranous viscerocranium?

A

squamous temporal b

maxillary b

zygomatic b

mandible (from cells of mandibular prominence, but NOT meckel’s cartilage)

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12
Q

What is craniosynostosis in general?

A

premature fusion of cranial sutures, often assoc w/ other skeletal defects

cause unclear

more common in boys

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13
Q

What is scaphocephaly?

A

premature closure of sagittal suture –> cranium becomes long, narrow, and wedge shaped

50% of cases of craniosynostosis

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14
Q

What is brachycephaly?

A

premature closure of coronal suture –> high, tower-like cranium

30% of cases of CSS

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15
Q

What is plagiocephaly?

A

early closure of coronal suture on one side –> cranium is twisted and asymmetric

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16
Q

What is trigonocephaly?

A

premature closure of the frontal (metopic) suture

deformities of frontal and orbital bones in addn to other anomalies

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17
Q

What do the medial nasal prominences form?

A

nasal septum

ethmoid bone

cribriform plate

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18
Q

What occurs to the face early in 4th week?

A

5 facial primordia appear as prominences around the stomodeum

2 MXP

2 MDP

1 FNP

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19
Q

What is the stomodeum?

A

early mouth hole

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20
Q

What is the oropharyngeal membrane?

A

bilaminar membrane over stomodeum that separates facial primordia from primordial pharynx

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21
Q

When does facial dev occur?

A

4-8 weeks

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22
Q

What types of germ cells are the active growth centers in the FNP, MXP, and MDPs?

A

NCC

from forebrain and midbrain in FNP

from midbrain and hindbrain in MXP and MDP

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23
Q

What are the first parts of the face to form and how does this occur?

A

lower jaw and lower lip

oropharyngeal membrane disintigrates –> extension and fusion of mandibular prominences at midline

*mandibular arch first to fuse*

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24
Q

What has occured to the face by the end of the 4th week?

A

nasal placodes form on inferolateral parts of FNP = thickenings of surface ectoderm that will form nasal epithelium

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25
How do the NPs change during development?
placodal edges proliferate --\> medial and lateral nasal prominences --\> placodes turn into nasal pits
26
What is the nasolacrimal groove?
separates LNP from maxillary prominence by end of 6th week --\> MXP and LNP fuse est continuity btw side of nose and cheek
27
How does the intermaxillary segment form and what does it give rise to?
MNPs merge w/ MXP and FNP btw 7th and 10th weeks = medial palatine process/intermaxillary segment forms philtrum of upper lip premaxillary part of maxilla (1st 2 teeth) primary palate
28
What does the mesenchyme in PA2 form?
facial muscles innervated by facial n (7)
29
What does the mesenchyme in PA1 form?
muscles of mastication (and others) trigeminal N (V)
30
When does the mandible reach its characteristic form?
by 14 weeks
31
How do the orbits get a fwd-facing orientation?
as brain enlarges --\> cranial cavity expands bilaterally
32
What is the oronasal membrane and what happens to it?
**S ecto** that initially separates the oral cavity and nasal sac --\> ruptures at 6th week --\> makes oropharynx and nasopharynx continuous
33
What occurs to the epithelium lining the roof of nasal cavities during dev?
specializes --\> olfactory epithelium
34
When does palatogenesis occur?
2 stages 6th to 12th week critical period: 6-9
35
What forms the median palatine process and what is it?
merging of MNPs --\> median palatine process/primary palate mesenchyme btw MXPs forms premaxillary part of maxilla
36
When and how does the secondary palate form?
early in 6th week MXP has lateral palatal shelves = mesenchyme projections --\> move inferomedially and merge w/ primary palate --\> keep fusing in A-P pattern done at 7-8th week?
37
Why is tongue movement during development important?
Must move inferiorly and anteriorly to give the secondary palate space to grow and fuse if it doesn't move --\> cleft palate
38
What is the palatine raphe?
line of fusion of lateral palatine processes
39
What is the incisive fossa?
remnant of nasopalatine canal in normal adults in the medial plane of the palate
40
What is a cleft lip?
extends from upper lip often to nose and/or maxilla failure of MXP and MNP to fuse
41
What is a cleft palate?
cleft of secondary palate to incisive fossa failure of LPPs w/ nasal septum or LPP w/ medial palatine process
42
When does the nasal septum fuse w/ palatine processes?
begins anteriorly at 9th week --\> complete posteriorly week 12
43
What are the lingual swellings and what do they come from?
median lingual swelling = appears at end of 4th week; 1st part of tongue dev lateral lingual swellings = rapidly grow, merge and overgrow median both from PA1
44
What do all the tongue buds resulf from initially?
mesenchyme from PA1
45
what is the embryo origin of anterior 2/3 of tongue? Posterior 1/3?
PA1 PA3
46
What is the terminal sulcus?
line of fusion of anterior and posterior parts of tongue
47
What is the hypopharyngeal/hypobranchial eminence?
initial part of tongue from PA3 and Pa4 that overgrow copula form arch 2
48
What is the tongue musculature derived from?
myoblasts of occipital myotomes --\> CN 12 innervates them
49
What does the epiglottis form from?
fourth arch
50
What is glossoschissis?
bifid tongue
51
What is ankyloglossia?
tongue tied
52
What does innervation of vallate papilla in the ant 2/3 of tongue?
CN 9
53
What does the vagus n do in the tongue?
sensory of posterior tongue and pharynx tast to epiglottis motor to palatoglossus m
54
How do teeth develop initially?
from cell-cell interactions btw NC mesenchyme and overly ectoderm
55
What are dental laminae?
U-shaped bands of oral epithelium = 10 on top, 10 on bottom --\> form tooth buds, done by 6th week
56
What are the parts of the cap staged tooth?
enamel organ dental papilla = mesenchyme --\< dentin and pulp dental sac = mesenchyme surrounding all of it --\> PDL and cementum
57
What makes up the enamel organ?
ecotdermal cells outer layer = outer enamel epi inner layer = inner enamel epithelium
58
What do dental papilla cells next to IEE form in bell stage?
odontoblasts --\> predentin --\> dentin
59
What does the IEE form in the bell stage?
ameloblasts in response to dentin production --\> enamel
60
When does root dev occur?
after dentin and enamel formation IEE and OEE fuse --\> grows into mesenchyme and initiates root formation odontoblasts make root dentin
61
What do the different cells of the dental sac form?
inner cells --\> cementoblast --\> cementin around roots outer cells --\> PDL = collagen L that anchors tooth to bone
62
What allows deciduous teeth to fall out?
as permanent teeth grow --\> osteoclasts resorb deciduous root only crown and uppermost part of root are shed
63
What do permanent teeth develop from?
buds from posterior extensions of the dental laminae
64
What is the epithelium covering the post 1/3 of the tongue derived from?
endoderm

NS-1 (50 decks)

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