Development of Orofacial Structures Flashcards
which bones in the neurocranium form by endochondral ossification?
occipital bone–> body of sphenoid bone—> ethmoid bone, and the petrous and mastoid parts of the temporal bone
which bones in the neurocranium form by intramembranous ossification?
frontal bone and the parietal bones
which bones in the viscerocranium form by endochondral ossification?
malleus and incus (PA1), stapes, styloid process of temporal bone, and lesser horn of hyoid bone (PA2), greater horns of hyoid bone (PA3), laryngeal cartilages (PA4)
which bones of the viscercranium form by intramembranous ossification?
squamous temporal bones, maxillary, zygomatic bones, and the mandible
what is the term for premature fusion of the sutures?
craniosynostosis
which suture is prematurely closed in scaphocephaly?
sagittal suture
how does the cranium look with cases of scaphocephaly?
long, narrow, and wedge shaped
which suture is prematurely closed in brachycephaly?
coronal suture
how does the cranium look in cases of brachycephaly?
high, tower-like, dome-shaped
which suture is prematurely closed in plagiocephaly?
coronal or lambdoidal suture on ONE SIDE
how does the cranium look in cases of plagiocephaly?
twisted and asymmetric
which suture is prematurely closed in trigonocephaly?
frontal (metopic) suture
how does the cranium look in cases of trigonocephaly?
malformation of the frontal and orbital bones
what are the facial primordia?
1 frontonasal prominence, 2 maxillary prominences, and 2 mandibular prominences
what is the term for the primitive mouth?
stomodeum
when does the oropharyngeal membrane rupture?
day 26
what happens when the oropharyngeal membrane ruptures?
facial development begins
what is the first part of the face to form?
lower jaw/lower lip
when do nasal placodes form on the inferolateral parts of the FNP?
end of the 4th week
what happens when the nasal placode edges proliferate?
it produces a medial and lateral nasal prominence
what do the nasal pits eventually form?
nostrils and nasal cavities
what do the lateral nasal prominences form?
alae (sides) and the nose
what structure in the pharyngeal apparatus forms the external auditory meatus?
1st groove
how does the medial nasal prominence move toward the midline?
with the maxillary prominences growing toward midline
when the maxillary prominences make contact with the lateral nasal prominences, what does it form?
nasolacrimal groove
when will the nasolacrimal groove begin to fill in?
by the end of the 6th week
what is the lateral nasal prominence and the maxillary prominence separated by?
the nasolacrimal groove
When does facial development occur?
between the 4th and 8th weeks
Which pharyngeal arch does the maxillary prominence and mandibular prominence come from?
PA 1
Where do the MNP and LNP leave and go sit?
nasal pit
what are nasal placodes derived from?
surface ectoderm
when do medial nasal prominences merge with maxillary and lateral nasal prominences?
between the 7th-10th weeks
as the medial nasal prominences merge, what forms?
the intermaxillary segment
what is considered the premaxillary part of the maxilla?
the intermaxillary segment
what is considered the core of the philtrum of the upper lip derived from?
the intermaxillary segment
the surface of the upper lip is derived from what?
the maxillary prominence
most of the upper lip, maxilla, and secondary palate forms from what?
maxillary prominences
what are the primordial nasal sacs separated from the oral cavity by?
oronasal membrane
when does the oralnasal membrane rupture?
end of the 6th week
when does palatogenesis begin?
6th week of development
when does palatogenesis end?
by 12th week
what is considered the critical period of palatogenesis?
end of 6th week–> beginning of 9th week
what is another name for the intermaxillary segment?
the median palatine process
when does development of the secondary palate occur?
early in the 6th week
what does the secondary palate develop from?
the lateral palatine processes aka the palatine shelves
what does the lateral palatine processes/ palatine shelves arise from?
mesenchyme of the maxillary prominences
what is the first step in development of the secondary palate?
the palatine processes will extend inferiorly on each side of the tongue
what happens in the face that moves the tongue out of the way when the secondary palate is growing?
the mandible elongates, which pulls the tongue forward and down
what is the final step of the formation of the secondary palate?
the palatine processes will “flip” horizontally to be above the tongue
when is secondary palate formation complete?
7-8th weeks of development
how is the hard palate formed?
when bone extends from the maxillae and palatine bones into the lateral palatine processes
what indicates the line of fusion in the palate?
the palatine raphe
in cases of cleft lip, what is there a lack of fusion of?
lack of fusion between the maxillary prominences and median nasal prominences
in cases of cleft palate, what is there a lack of fusion between?
lack of fusion between either the lateral palatine processes with the nasal septum or the lateral palatine process with the median palatine process
what is the nasal septum?
down growth from internal parts of merged medial nasal prominences
when does fusion of nasal septum and the palatine process begin?
9th week
when is fusion of the nasal septum and the palatine process completed?
by the 12th week
what is the first indication of tongue development?
the median lingual swelling
where is the median lingual swelling located?
in the floor of the primordial pharynx
when does the median lingual swelling appear?
at the end of the 4th week
what is located on each side of the median lingual swelling?
lateral lingual swellings
all tongue buds result from what?
proliferation of mesenchyme in the ventromedial parts of PA1
what happens to the lateral lingual swellings?
they rapidly proliferate, merge, and overgrow the median lingual swelling
what do the merged lateral lingual swellings form?
the oral part, anterior 2/3 of the tongue
when the ventromedial parts of PA2 fuse, what do they form?
the copula
what do the ventromedial parts of PA3 and PA4 develop?
the hypopharyngeal eminence
what happens to the hypopharyngeal eminence?
it overgrows the copula, forming the posterior 1/3 of the tongue
tongue musculature is derived from what?
myoblasts of the occipital myotomes
what is incomplete fusion of the lateral lingual swelling/ bifed tongue?
glossoschissis
what is it called when the frenulum is short and extends to the tip of the tongue?
ankyloglossia
