development of the face and palate Flashcards
mid 4th week
1) beginning elements of the facial development and boundaries of the stomatodeum are apparent
2) buccopharyngeal membrane will rupture by end of 4th week
- frontonasal process
- mandibular process (from branchial arch I)
- maxillary process (from branchial arch I)
3) odontogenic epithelium of mandibular process
- will differentiate into teeth
end of 4th week
1) medial and lateral nasal process
- horseshoe shape beginning of the nose
2) flat part called nasal placode
early 5th week
1) nasal placode grows inward to make nasal pit
2) FP, MNP, LNP, Mx, Mnd
later 5th week
1) 36 day embryo
2) maxillary process fuses with the mesial nasal process on each side to complete the formation of the upper lip
early 6th week
1) 38 days or 6 weeks
2) it has to be fused and complete upper lip is present
3) two mesial nasal processes merge to form the intermaxillary segment
- center of the upper lip, philtrum, alveolar process for the incisors and the primary palate
4) lower lip formed by the merging of the two streams of ectomesenchyme of the mandibular process
later 6th week
1) formation of the nasolacrimal duct
- formed from floor of naso-optic groove
- then the LNP and Mx process will merge, and the naso-optic groove disappears
2) eye, LNP, IMS, Mx, Mnd, external ear
3) bucconasal groove
- connects max process with medial nasal process
4) naso-optic groove
- connects lateral nasal process with the Mx
adult face
1) medial nasal process
- median cleft lip
2) lateral nasal process
- oblique facial cleft
3) maxillary process
- bilateral cleft lip
4) mandibular process
failure of fusion leads to these conditions
development of the palate
1) primary palate
medial nasal processes fuse and form intermaxillary segment
2) secondary palate
primary palate formation
1) from the medial nasal processes of both sides together (intermaxillary segment) with the frontonasal process
=> primary palate
2) breakdown of the thin layer of the base of nasal pit and oral cavity
=> anterior nares
3) at the back of the anterior nares
=> oronasal membrane (primary choanae)
the completed primary palate
1) anterior nares
- oronasal membrane will rupture
2) primary choanae
- the communicating opening between the stomodeum and the nose
3) primary palate
- anterior part of the hard palate
primary palate
1) intermaxillary segment gives rise to…
2) primary palate which becomes the hard palate anterior to the incisive foramen and the alveolus containing tooth buds for central and lateral incisors
formation of the secondary palate
1) palatal shelves originate as downgrowths from the maxillary processes in the 7th and the 8th weeks
2) vertical growth continues and completes around 3rd month of gestation
secondary palate formation
1) 7th week
- nasal septum forms
- tongue moves down
2) 8th week
- palatal shelf elevation
3) 9-12th weeks
- more advancement, the palatal shelves will meet in midline
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during palate formation, there is a fusion of palatal processes, involving the breakdown of surface epithelium
closure of the secondary palate
1) fusion of palatal shelves at midline epithelial seam
cleft palate
1) 6/10,000 births for cleft palate
- a little more for cleft lip