Lecture 13: Development of Orofacial Structures Flashcards
What does the viscerocranium become?
What is its embryological origin?
Facial skeleton
Mesenchyme
What does the neurocranium become?
What is its embryological origin?
Bones that enclose the brain
Mesenchyme
What bones form from the cartilagenous neurocranium?
- Occipital Bone
- Body of Sphenoid Bone
- Ethmoid Bone
- Petrous and mastoid parts of Temporal Bone
What bones arise from the membranous neurocranium?
Frontal and Parietal Bones
What bone initially begins as part of the viscerocranium and then migrates to become part of neurocranium?
Frontal Bone
Male newborn patient presents with a long, narrow, wedge-shaped head.
What is the most likely diagnosis? This most likely results from premature closure of what suture?
Scaphocephaly
Sagittal suture
Male infant that has a high, tower-like head may have what disorder? From premature closure of what suture?
Brachycephaly
Coronal suture
An infant presenting with a twisted, asymmetric head may have what disorder? Due to premature closure of what suture?
Plagiocephaly
Coronal suture
A premature closure of the frontal (metopic) suture may result in what disorder? What bones does this affect?
Trigonocephaly
Frontal and Orbital bones
What is the facial primordia?
What makes up the facial primordia?
Tissue that surrounds stromodeum (primitive mouth)
- 2 Maxillary Prominences
- 2 Mandibular Prominences
- 1 Frontonasal Prominence
What separates the the facial primordia from the pharyngeal pharynx?
Oropharyngeal Membane
In what weeks does facial development occur?
Weeks 4-8
How does the mandibular prominece fold?
What can incomplete fusion result in?
- Oropharyngeal membrane disintegrates
- Medial ends of both prominences merge
Incomplete fusion can lead to chin dimple
What does the maxillary prominences give rise to?
Upper Lip
Maxilla
Secondary Palate
What pharyngeal arch do the muscles of facial expression come from?
What do they invade into?
2nd Pharyngeal Arch
Invade primordial lips and cheeks to give facial expression muscles
What does the frontonasal prominence give rise to?
Forehead
Caudal boundary of stomodeum and nose
At the end of the 4th week, what forms on the inferolateral parts of the frontal nasal prominence?
Nasal placodes
What is the direct embryonic origin of the philtrum?
Fusion of Median Nasal Prominence
What seapartes lateral nasal prominence from maxillary prominence?
When do they fuse?
Nasolacrimal Groove
Fuses by Week 6
How does the auricle develop?
Six hillocks surround Pharyngeal Arch 1 and is pushed from the neck to side of the head when the mandible develops
What pharyngeal arch do the muscles of mastication arise from?
1st Pharyngeal Arch
What is the critical period for palatogenesis?
Weeks 6-9 (finishes development at 12)
What gives rise to the intermaxillary segment?
Medial Nasal Prominence
What part of the palate does the intermaxillary segment give rise to?
Primary palate
What is the embryonic origin of the secondary palate?
Lateral palatine processes (shelves) from the maxillary prominences
How do nasal cavities form?
- Nasal Placodes (thickened ectoderm) depress and form nasal pits (eventual nostrils)
- Primitve oronasal membrane is formed and disintegrates giving nasal sacs
What embryonic structures failed to fuse in cleft lip?
Maxillary prominences and median nasal prominences
What structures failed to fuse in a cleft palate?
Lateral palatine process w/ nasal septum and/or medial palatine process
When is the period of development of the nasal septum?
Weeks 9-12
Merged lateral lingual swellings form what part of the tongue?
Anterior 2/3
What pharyngeal arch does the anterior tongue arise from?
1st Pharyngeal Arch
What are the contributions of PAs 2,3, and 4 to form the posterior 1/3 of the tongue?
PA2 (ventromedial) - Copula
PA 3/4 (ventromedial) - hypopharyngeal eminence
Hypopharyngeal eminence overgrows copula to form posterior 1/3 of tongue
What embryological structures do tongue muscles arise from?
Myoblasts of occipital myotomes
NOT NCC
What is glossoschissis?
Bifid tongue (abnormal fusion of lateral lingual swellings)
What is ankyloglossia?
Attachment between tongue and floor of oral cavity is too long and anchors tongue down, limiting movement
What is the order of tooth bud formation? In what week?
Anterior mandibular => anterior maxillary => posterior
Week 6
What cells produce dentin?
Odontoblasts from dental papilla cells
What cells produce enamel?
Ameloblasts from inner enamel epithelium
What stage of odontogenesis are inner enamel and outer enamel epithelium formed?
Cap stage
What stage of odontogenesis are dentin and enamel formed?
Bell stage
What forms from fusino of the IEE and OEE?
Epithelial root sheath => dental root/dental sac
What forms the collagen ligament that anchors tooth to bone?
Outer cells of the dental sac
What cells are responsible for degenerating roots of baby teeth to make room for permanent teeth?
Osteoclasts
