Development of Orofacial Structures

Question 1

What is the cranium divided into?

Answer 1

Neurocranium and viscerocranium

Question 2

What is the neurocranium?

Answer 2

Mesenchyme-derived

Gives rise to bones that enclose brain

Question 3

What is the viscerocranium?

Answer 3

Mesenchyme-derived

Gives rise to bones that comprise facial skeleton

Question 4

What are the cartilaginous and membranous parts of the nerocranium?

Answer 4

Cartilaginous - occipital, sphenoid, ethmoid, petrous/mastoid parts of temporal
Membranous - frontal, parietal

Question 5

What are the cartilaginous and membranous parts of the viscerocranium?

Answer 5

Cartilaginous - NCC-derived bones from pharyngeal arches (ex malleus, incus, stapes, etc) and CT
Membranous parts - maxilla, squamous part temporal, zygomatic

Question 6

What is craniosynostosis?

Answer 6

Premature fusion of cranial sutures

Question 7

What is scaphocephaly?

Answer 7

Premature fusion of saggital suture. Long, narrow, wedge-shaped cranium

Question 8

What is brachycephaly

Answer 8

Premature fusion of coronal suture. High, tower-like cranium

Question 9

What is plagiocephaly?

Answer 9

Premature fusion of one side of coronal suture. Twisted and asymmetric head.

Question 10

What is trigonocephaly?

Answer 10

Premature fusion of frontal suture

Question 11

What are the 5 facial primordia?

Answer 11

2 maxillary prominences
2 mandibular prominences
1 frontonasal prominence

Question 12

When do the facial primordia appear?

Answer 12

Week 4

Question 13

What do the mandibular prominences give rise to?

Answer 13

Lower jaw and lower lip, they fuse together medially

Question 14

What do the maxillary prominences give rise to?

Answer 14

Upper lip, maxilla, secondary palate. Grow medially and fuse together. Merge with mandibular prominences laterally. Invaded by mesenchyme from pharyngeal arch 2 to form facial muscles

Question 15

What does the frontonasal prominence give rise to?

Answer 15

Forehead, back part of mouth, nose

Question 16

How does the nose develop from the frontonasal prominence?

Answer 16

Nasal placodes (surface ectoderm) swell up. Nasal pit appears, divides lateral nasal prominence from mediallnasal prominence.

Question 17

What happens to the median nasal prominences?

Answer 17

They shift toward midline, results in philtrum

Question 18

What happens to the lateral nasal prominences?

Answer 18

Form ala of nose, merge with maxillary prominence by end of week 6

Question 19

What does development of the mandible do to the ears?

Answer 19

Pushes them from neck to side of head at eye level

Question 20

What induces the nasal pits to become deeper and grow into the face to make nostrils?

Answer 20

Mesenchyme from the medial and lateral prominences

Question 21

What are the nasal pits called when they become deeper?

Answer 21

Nasal sacs

Question 22

What separates the primordial nasal sacs and when does it degenerate?

Answer 22

Oronasal membrane, ruptures at end of week 6

Question 23

When does palatogenesis occur?

Answer 23

Between weeks 6-12

Question 24

What happens during primary palate stage?

Answer 24

Fusion of median nasal prominences to form median palatine process

Question 25

What happens during secondary palate stage?

Answer 25

Develops from lateral palatine processes/palatal shelves.

Question 26

What happens during final palate stage?

Answer 26

Bone extends from maxillae and palatine bones to form the hard palate

Question 27

How does the nasal septum arise?

Answer 27

Downward growth of internal parts of merged medial nasal prominences that fuse with lateral palatine processes

Question 28

What is choanal atresia?

Answer 28

Bony abnormalities of the pterygoid plates, presents as upper airway obstruction, noisy breathing, cyanosis

Question 29

How does the anterior 2/3 of the tongue develop?

Answer 29

2 lateral tongue swellings grow and overtake the median lingual swelling at the end of the 4th week. Mesenchyme from PA 1

Question 30

How does the posterior 1/3 of the tongue develop?

Answer 30

The hypopharyngeal eminence (PA 3/4) overgrows the copula (PA 2)

Question 31

What nerve supplies the tongue musculature?

Answer 31

CN XII

Question 32

What is glossoschissis?

Answer 32

Bifid tongue

Question 33

What is ankyloglossia?

Answer 33

Short frenulum

Question 34

What is macroglossia?

Answer 34

Enlarged tongue

Question 35

What is the dental lamina?

Answer 35

Bands of epithelium that follow curves of primitive jaws

Question 36

What are tooth buds?

Answer 36

Form out of dental lamina, consist of enamel organ, dental papilla, and dental follicle/sac

Question 37

What is enamel organ?

Answer 37

Produces enamel

Question 38

What is dental papilla?

Answer 38

Internal part of tooth (dentin and pulp)

Question 39

What is dental follicle/sac?

Answer 39

Gives rise to cementum that holds tooth in place

Question 40

What do odontoblasts do?

Answer 40

Produce dentin

Question 41

What do amelobalsts do?

Answer 41

Produce enamel

Question 42

What are baby teeth called?

Answer 42

Deciduous teeth

Question 43

When do the buds for the 2nd/3rd permanent molars develop?

Answer 43

After birth