Embryology Development of Face, Skull, Palate

Question 1

what two embryological tissue types give rise to all of the skull

Answer 1

neural crest

sclerotome portion of somite

Question 2

neural crest disorder?

Answer 2

facial defects

Question 3

anterior portion of the skull forms from what

Answer 3

neural crest cells

Question 4

posterior portion of the skull forms from

Answer 4

paraxial mesoderm

Question 5

when do the anterolateral fontanelles close?

Answer 5

about 6 months

Question 6

when do the posterolateral fontanelles close?

Answer 6

about 6 months

Question 7

when does the anterior fontanelle close

Answer 7

18 months

Question 8

what are fontanelles

Answer 8

soft spots- large sheets of CT

allow for growth of skull postnatally

allow calvaria to undergo changes in shape (molding) during birthing

anterior, posterior, posterolateral, anterolateral

the flat bones grow together postnatally but the cranial sutures remain flexible throughout childhood

Question 9

what is craniosynostosis and what are the two types?

Answer 9

abnormal sutures (close to early, etc.)

scaphocephaly

Question 10

scaphocephaly

Answer 10

early fusion of SAGITTAL suture

skull is long A-P and narrow (transverse)

Question 11

brachycephaly

Answer 11

early fusion of coronal suture

skull is short (A-P) and wide transverse

Question 12

what does the face form from

Answer 12

three, paired prominences (from 1st arch) form most of the features of the face

Question 13

what does the frontonasal prominence form

Answer 13

a. Forehead
b. Bridge of nose and nasal septum
c. Medial nasal prominences – apex of nose, philtrum of upper lip
d. Lateral nasal prominences – ala of nose

Question 14

what does the maxillary prominences form

Answer 14

a. Upper cheek

b. Lateral portions of upper lip

Question 15

what does the mandibular prominences form

Answer 15

Chin, lower cheek region

b. Lower lip
c. Part of external ear

Question 16

what are nasal placodes?

Answer 16

thickening of surface ectoderm that forms on frontonasal prominence and the invaginates to form nasal pits

Question 17

what do medial and lateral nasal prominences form from

Answer 17

mesenchyme surrounding the margins of the nasal pits proliferates to form these two structures

Question 18

what is the development of medial nasal prominences

Answer 18

pushed towards midline and will fuse with one another (forming the intermaxillary segment)

Question 19

what is the upper lip formed from

Answer 19

intermaxillary segment fusing with adjacent maxillary prominence

Question 20

what else does the intermaxillary segment gives rise to besides part of the upper lip

Answer 20

philtrum and primary palate

Question 21

what does the nose develop from ?

Answer 21

frontonasal prominence, lateral nasal prominence and medial nasal prominence

Question 22

what does the upper lip develop from?

Answer 22

medial nasal prominence and maxillary prominence

Question 23

lower lip develops from what?

Answer 23

mandibular prominence

Question 24

how does the nasolacrimal duct form

Answer 24

1. The maxillary prominence fuses with the lateral nasal prominence along the nasolacrimal groove.
2. The nasolacrimal duct forms from the ectoderm of nasolacrimal groove.

Question 25

how do the nasal cavities and paranasal sinuses form?

Answer 25

nasal pits deepen and grow dorsally, produce nasal sacs

nasal sacs are separated from oral cavity by oronasal membrane

oronasal membrane ruptures by 6th week, replaced by palate

olfactory epithelium and CNI develop from nasal sac ectoderm

paranasal sinuses develop slowly through puberty

Question 26

what do the olfactory epithelium and CN I develop from

Answer 26

nasal sac ectoderm

Question 27

muscles of mastication are derived from which pharyngeal arch ?

Answer 27

1st pharyngeal arch (trigeminal)

Question 28

muscles of facial expression form from which pharyngeal arch?

Answer 28

2nd pharyngeal arch (facial n)

Question 29

what does the primary palate form from and what does it fuse with

Answer 29

1. The maxillary prominence fuses with the lateral nasal prominence along the nasolacrimal groove.
2. The nasolacrimal duct forms from the ectoderm of nasolacrimal groove.

Question 30

what do lateral palatine shelves form from

Answer 30

maxillary prominences

Question 31

how does the secondary palate form

Answer 31

3. During weeks 7-8, the palatine shelves migrate superiorly and fuse with one another, the primary palate, and in the midline with the nasal septum.
4. Ossification occurs in anterior 2/3rds of palate to form hard palate.
5. The incisive foramen is the landmark between primary and secondary palates.

Question 32

what does the incisive foramen demarcate ?

Answer 32

the landmark b/w primary and secondary palates

Question 33

what is the most common craniofacial anomaly

Answer 33

clefts of the lip and palate

Question 34

what is the cause of anterior clefts?

Answer 34

separates the primary from the secondary plate

caused by failure of maxillary prominence to fuse with mideal nasal prominence (intermaxillary segment)

Question 35

what is the cause of a median cleft of lip ?

Answer 35

failure of medial nasal prominences to merge (rare)

Question 36

what is the cause of a posterior cleft?

Answer 36

lack of fusion of lateral palatine plates

cleft palate and/or uvula

Question 37

what is the cause of an oblique facial cleft

Answer 37

failure of maxillary process to fuse with lateral nasal prominence

runs from mouth towards eye

results in nasolacrimal duct not being incorporated into the face

Question 38

what do craniofacial defects result from many times?

Answer 38

disruption of nasal crest cell migration or differentiation in the face

Examples include Treacher collin’s

DiGeorge anomaly

Question 39

DiGeorge

Answer 39

Chromosome 22
-Cardiac defects
-Abnormal facies
-Thymic aplasia
-Cleft palate
-Hypocalcemia 
    (parathyroid 
      deficiency)