Development of Orofacial Strucutes

Question 1

What is neurocranium derived from? What does it give rise to?

Answer 1

Mesenchyme, cartilaginous and membranous components

Bones that enclose the brain: frontal, parietal, occipital, petrous part of temporal

Question 2

What is viscerocranium derived from? What does it give rise to?

Answer 2

Mesenchyme

Facial skeleton: nasal, lacrimal, zygomatic, maxilla, incisive, mandible, sphenoid, squamous part of temporal

Question 3

What do the cartilaginous parts of neurocranium give rise to? Membranous parts?

Answer 3

Occipital bone, body of sphenoid, ethmoid bone, petrous and mastoid parts of temporal bone

Calvaria= frontal and parietal bones

Question 4

What do the cartilaginous parts of viscerocranium give rise to? Membranous parts?

Answer 4

NCC –> bones and connective tissue

Maxillary prominence, squamous part of temporal, maxilla, zygomatic bone

Question 5

What is scaphocephaly?

Answer 5

Premature fusion of sagittal suture

Long narrow wedge shaped cranium

Question 6

What is brachycephaly?

Answer 6

Premature fusion of entire coronal suture

High tower like cranium

Question 7

What is plagiocephaly?

Answer 7

Premature fusion of one side of coronal suture

Twisted and asymmetric

Question 8

What is trigonocephaly?

Answer 8

premature fusion of frontal suture

Question 9

What is derived from the frontal nasal prominence?

Answer 9

Forehead
Dorsum/apex of nose
Rostal boundary of stomodeum

Question 10

What is derived from the lateral nasal prominence? What separates it from the maxillary prominence? When does it merge with the maxillary?

Answer 10

Alae of nose (nasal flaring)

nasolacrimal groove

End of week 6

Question 11

What is derived from the medial nasal prominence? What regulates its growth?

Answer 11

Nasal septum
Ethmoid bone
Cribiform plate

PDGFRA, shifted towards midline with medial growth of maxillary prominence

Question 12

What is derived from the maxillary prominence? What is the process?

Answer 12

Upper cheek
Upper Lip

Maxillary prominence grows medially and merges laterally with mandibular prominence

Invaded by mesenchyme from PA2 –> facial muscles

Question 13

What is derived from the mandibular prominence? What is the process? What happens if there is incomplete fusion?

Answer 13

Chin
Lower lip
Cheek

Caused when oropharnygeal membrane disintegrates and medial ends of mandibular prominence merge

chin dimple.

Question 14

When does the facial primordia appear? What is its structure?

Answer 14

week 4
Surrounds stomodeum= primitive oral cavity
Separated from primordial pharynx by oropharyngeal membrane which ruptures day 26

Question 15

How are the medial and lateral prominences formed?

Answer 15

Nasal placodes (thickened surface ectoderm) on inferolateral portion of the frontonasal prominence proliferate causing horse shoe shaped elevations –> medial and lateral nasal prominences –> primordial nasal snares

Question 16

How is the philtrum/intermaxillary segment formed?

Answer 16

Fusion of median nasal prominence and maxillary

Above midline of upper lip

Question 17

What signaling molecule responsible for development of mandibular process?

Answer 17

BMP

Question 18

How are nasal cavities formed?

Answer 18

Nasal placodes (ectoderm) depress and form nasal pits
Mesenchyme from medial and lateral proinences induce pits to become deeper --> primordial nasal sacs which grow dorsally and ventrally to forebrain, separated by oronasal membrane which ruptures end of week 6

Question 19

What is the primordial choanae?

Answer 19

Connection between nasopharynx and nasal cavity

Question 20

What is the nasal conchae?

Answer 20

Superior middle and inferior turbinate

Can become inflamed with allergies (rhinitis)

Question 21

What does olfactory epithelium become?

Answer 21

Olfactory n.

In Parkinson’s symptom is losing sense of smell prior to onset of normal symptoms

Question 22

What are the 2 stages of platogenesis? When do they occur? What is the critical period?

Answer 22

Primary= fusion of median nasal prominences forms median palatine process –> premaxillary part of mazilla

Secondary= develop from lateral palatine processes (palatal shelves) which are mesenchymal projections extending from internal aspects of maxillary prominence

Weeks 6-12
critical= end of week 6-beginning of week 9

Question 23

How do we get our final palate?

Answer 23

Bone extends from maxillae and palatine bones into lateral palatine processes to form hard palate
- posterior portions do not ossify –> soft palate and uvula

Question 24

What is the palatine raphe?

Answer 24

Line of fusion

Question 25

What is the incisive fossa?

Answer 25

Remnant of nasopalatine canal

Question 26

How do we get the nasal septum?

Answer 26

Downward growth of internal parts of merged medial nasal prominences Fuses with lateral palatine processes anterior to posterior

Question 27

What causes cleft lip and/or palate? What are risk factors?

Answer 27

Defects in fusion Genetics: SATB2, SHH, TGF-alpha, TGF-B3, IRF6 antiepileptic drugs, smoking binge drinking, folate deficiency, obesity

Question 28

What is choanal atresia? How does it present?

Answer 28

bony abnormalities of pterygoid plates and midfacial growth abnormalities? upper airway obstruction, noisy breathing, cyanosis that worsens during feeding and improves with crying Connected to Treacher-collins (arch 1) CHARGE, Kallman, or VACTERL syndromes

Question 29

How does the oral part (anterior 2/3) of the tongue develop?

Answer 29

Median tongue bud appears at end of 4th week and then two lateral swelling develop on either side Induced by PA 1

Question 30

How does the pharyngeal part (post 2/3) of tongue develop?

Answer 30

Copula= PA2 hypopharyngeal eminence= PA3 and 4, eventually overgrows copula and fusion at terminal sulcus of oral and pharyngeal parts

Question 31

What innervates the mucosa, taste, taste buds, and musculature of the anterior 2/3 of the tongue?

Answer 31

mucosa= Lingual branch of V3 taste= Chorda Tympani (CN VII) taste buds= CN IX musculature= CN XII

Question 32

What innervates the mucosa, taste, taste buds, and musculature of the posterior 1/3 of the tongue?

Answer 32

Mucosa and taste= CN IX Musculature= CN XII Sensation to pharynx= CN X Palatogglossus m.= CN X

Question 33

What is clossochissis?

Answer 33

Bifid tongue

Question 34

What is ankyloglossia?

Answer 34

``` Short frenulum (attaches inferior tongue to oral cavity Can present with problems breastfeeding and speaking ```

Question 35

What is macroglossia?

Answer 35

Big tongue | Associated with downs, beckwith-wiedemann, muscopolysaccharidoses

Question 36

What induces odontogenesis?

Answer 36

Communication between NCCs and oral epithelium (ectoderm)

Question 37

What is the cap stage of odontogenesis?

Answer 37

Tooth bud becomes cap shaped when invested by mesenchyme

Question 38

What does the tooth bud consist of?

Answer 38

Enamel organ= ectodermal cells from dental lamina --> enamel Dental papilla= internal part of tooth --> dentin and pulp Dental follicle/sac= mesenchyme surrounding papilla and enamel organ -- >cementum

Question 39

What is the bell stage of odontogenesis?

Answer 39

Enamel organ becomes bell shaped due to differentiation of enamel

Question 40

What do odontoblasts give rise to?

Answer 40

Predentin calcified to give dentin | Comes from dental papilla cells next to inner enamel epithelium

Question 41

What do ameoblasts give rise to?

Answer 41

Enamel | Inner enamel epithelium differentiates in response to dentin production

Question 42

How does the root of the tooth form?

Answer 42

Epithelial root sheath= fusion of outer and inner enamel Pulp= central dental papilla Cementum= inner cells of dental sac from cementoblasts Periodontal ligament= outer cells of dental sac

Question 43

What erupts through epithelium when your tooth erupts?

Answer 43

Root of tooth and crown Mandibular teeth erupt first Deciduous root resorbed by odontoclasts and crown and upper root are shed

Question 44

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

Answer 44

After birth | Why you have to get your wisdom teeth out

Question 45

When do deciduous permanent teeth appear?

Answer 45

10 weeks | extension of dental lamina, lingual to deciduous tooth buds

Question 46

What is the epithelium covering the posterior 1/3 of the tongue derive from?

Answer 46

Endoderm

Question 47

What is the hypobranchial eminence derived from?

Answer 47

PA 3 and 4

Question 48

What is derived from the dental lamina?

Answer 48

enamel organ

Question 49

What tissue gives rise to the dental sac?

Answer 49

Head mesenchyme

Question 50

What is the philtrum of the upper lip derived from?

Answer 50

medial nasal prominence