10: Orofacial Development Flashcards
Two ossification processes involved in cranium development and explain them
Intramembranous ossification: mesenchyme produces bone without cartilage
Endochondral ossification: bone formation occurs using a cartilagenous intermediate
Two pats of the cranium and explain them
Neurocranium: bony case that encloses brain
Viscerocranium: bones comprising facial skeleton
Five things formed by cartilagenous neurocranium
- Occipital bone
- Body of sphenoid
- Ethmoid bone (these three in order)
- Temporal bone: petrous and mastoid parts
What forms the membranous neurocranium
Head mesenchyme at the sides and top of brain
What does the membranous neurocranium form?
Calvaria (frontal and parietal bones)
Cartilagenous viscerocranium
NCCs form pharyngeal arches
Membranous viscerocranium: three things formed
- Squamous part of temporal bones
- Maxillary bone
- Zygomatic bones
What does the mandible form from?
Cells of the mandibular prominence
Craniosynostosis
Premature closing of certain sutures
Four types of craniosynostosis
- Scaphocephaly
- Brachiocephaly
- Plagiocephaly
- Trigonocephaly
Scaphocephaly
Sagittal suture closes -> cranium long, narrow, and wedge shaped (50% of cases)
Brachiocephaly
Coronal suture closes -> high, tower-like cranium (30%)
Two types of plagiocephaly and describe them
Posterior plagiocephaly: unilaterally impacts lambdoid suture
Anterior plagiocephaly: unilaterally impacts coronal suture
Trigonocephaly
Frontal suture closes -> metopic suture -> malformation of frontal and orbital bones
What is mesenchyme doing during 4-8th weeks of development
It contains active growth centers
Which portions of the brain NCCs are related to MXPs, MNPs, and the FNP?
MXPs and MNPs: midbrain, hindbrain NCCs
FNP: midbrain, forebrain NCCs
Oropharyngeal membrane
A bilaminar membrane that separates the facial primordia from cavity of primordial pharynx
When do nasal placodes form by?
End of 4th week
What is occurring simultaneously as the mid face is developing?
PA2 is forming facial muscles, PA1 is forming muscles of mastication
Critical period of palatogenesis
End of 6th week -> beginning of 9th week
Primary palate in palatogenesis
Wedge-shaped mass of mesenchyme, between maxillary prominences
What does the primary palate in palatogenesis form?
Pre-maxillary part of maxilla
What forms the secondary palate?
Mesenchyme of maxillary prominences
Incisive fossa is the persistence of what?
Nasopalatine canal
Palatine raphe indicates…?
Indicates line of fusion of the palate
What causes cleft lip?
Lack of fusion between MXPs + medial NPs
What causes cleft palate?
Lack of fusion between…
- Lateral palatine process + nasal septum
- Lateral palatine process + medial palatine process
When does the nasal septum fuse with palatine processes?
9th week -12th week
Other names for medial and lateral lingual swellings
Medial and lateral tongue buds
N to medial and lateral tongue buds / lingual swellings
Medial: lingual branch of V3
Lateral: chorda tympani of CN 7
What forms all tongue buds?**
Prolif of mesenchyme in ventromedial parts of PA1
sensory N to hypopharyngeal eminence
Branch of CN 12, superior laryngeal branch of CN 10
N to intrinsic tongue muscles + to palatoglossus muscle
Intrinsic: CN 12
Palatoglossus: pharyngeal plexus via CN 10
Glossoschissis
Incomplete fusion of lateral lingual swellings -> bifid tongue
Ankyloglossia
Frenulum is short + extends to top of tongue - tongue tied and trouble eating
Macroglossia
Excessively large tongue, often seen in infants with Down syndrome
Macroglossia
Abnormally small tongue, usually associated with micrognathia
