development of the face and palate

Question 1

mid 4th week

Answer 1

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

Question 2

end of 4th week

Answer 2

1) medial and lateral nasal process
- horseshoe shape beginning of the nose
2) flat part called nasal placode

Question 3

early 5th week

Answer 3

1) nasal placode grows inward to make nasal pit
2) FP, MNP, LNP, Mx, Mnd

Question 4

later 5th week

Answer 4

1) 36 day embryo
2) maxillary process fuses with the mesial nasal process on each side to complete the formation of the upper lip

Question 5

early 6th week

Answer 5

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

Question 6

later 6th week

Answer 6

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

Question 7

adult face

Answer 7

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

Question 8

development of the palate

Answer 8

1) primary palate
medial nasal processes fuse and form intermaxillary segment
2) secondary palate

Question 9

primary palate formation

Answer 9

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)

Question 10

the completed primary palate

Answer 10

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

Question 11

primary palate

Answer 11

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

Question 12

formation of the secondary palate

Answer 12

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

Question 13

secondary palate formation

Answer 13

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
–
during palate formation, there is a fusion of palatal processes, involving the breakdown of surface epithelium

Question 14

closure of the secondary palate

Answer 14

1) fusion of palatal shelves at midline epithelial seam

Question 15

cleft palate

Answer 15

1) 6/10,000 births for cleft palate
- a little more for cleft lip