Development of Orofacial Structures Flashcards
What is the cranium divided into?
Neurocranium and viscerocranium
What is the neurocranium?
Mesenchyme-derived
Gives rise to bones that enclose brain
What is the viscerocranium?
Mesenchyme-derived
Gives rise to bones that comprise facial skeleton
What are the cartilaginous and membranous parts of the nerocranium?
Cartilaginous - occipital, sphenoid, ethmoid, petrous/mastoid parts of temporal
Membranous - frontal, parietal
What are the cartilaginous and membranous parts of the viscerocranium?
Cartilaginous - NCC-derived bones from pharyngeal arches (ex malleus, incus, stapes, etc) and CT
Membranous parts - maxilla, squamous part temporal, zygomatic
What is craniosynostosis?
Premature fusion of cranial sutures
What is scaphocephaly?
Premature fusion of saggital suture. Long, narrow, wedge-shaped cranium
What is brachycephaly
Premature fusion of coronal suture. High, tower-like cranium
What is plagiocephaly?
Premature fusion of one side of coronal suture. Twisted and asymmetric head.
What is trigonocephaly?
Premature fusion of frontal suture
What are the 5 facial primordia?
2 maxillary prominences
2 mandibular prominences
1 frontonasal prominence
When do the facial primordia appear?
Week 4
What do the mandibular prominences give rise to?
Lower jaw and lower lip, they fuse together medially
What do the maxillary prominences give rise to?
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
What does the frontonasal prominence give rise to?
Forehead, back part of mouth, nose
How does the nose develop from the frontonasal prominence?
Nasal placodes (surface ectoderm) swell up. Nasal pit appears, divides lateral nasal prominence from mediallnasal prominence.
What happens to the median nasal prominences?
They shift toward midline, results in philtrum
What happens to the lateral nasal prominences?
Form ala of nose, merge with maxillary prominence by end of week 6
What does development of the mandible do to the ears?
Pushes them from neck to side of head at eye level
What induces the nasal pits to become deeper and grow into the face to make nostrils?
Mesenchyme from the medial and lateral prominences
What are the nasal pits called when they become deeper?
Nasal sacs
What separates the primordial nasal sacs and when does it degenerate?
Oronasal membrane, ruptures at end of week 6
When does palatogenesis occur?
Between weeks 6-12
What happens during primary palate stage?
Fusion of median nasal prominences to form median palatine process
What happens during secondary palate stage?
Develops from lateral palatine processes/palatal shelves.
What happens during final palate stage?
Bone extends from maxillae and palatine bones to form the hard palate
How does the nasal septum arise?
Downward growth of internal parts of merged medial nasal prominences that fuse with lateral palatine processes
What is choanal atresia?
Bony abnormalities of the pterygoid plates, presents as upper airway obstruction, noisy breathing, cyanosis
How does the anterior 2/3 of the tongue develop?
2 lateral tongue swellings grow and overtake the median lingual swelling at the end of the 4th week. Mesenchyme from PA 1
How does the posterior 1/3 of the tongue develop?
The hypopharyngeal eminence (PA 3/4) overgrows the copula (PA 2)
What nerve supplies the tongue musculature?
CN XII
What is glossoschissis?
Bifid tongue
What is ankyloglossia?
Short frenulum
What is macroglossia?
Enlarged tongue
What is the dental lamina?
Bands of epithelium that follow curves of primitive jaws
What are tooth buds?
Form out of dental lamina, consist of enamel organ, dental papilla, and dental follicle/sac
What is enamel organ?
Produces enamel
What is dental papilla?
Internal part of tooth (dentin and pulp)
What is dental follicle/sac?
Gives rise to cementum that holds tooth in place
What do odontoblasts do?
Produce dentin
What do amelobalsts do?
Produce enamel
What are baby teeth called?
Deciduous teeth
When do the buds for the 2nd/3rd permanent molars develop?
After birth
