13.0 Development of Orofacial Structures Flashcards
What are the cartilaginous parts of the neurocranium? What are the membranous parts?
Cartilaginous: occipital bone, body of sphenoid bone, ethmoid bone, petrous and mastoid parts of the temporal bone. Membranous: Calvaria (frontal and parietal bones)
What are the cartilaginous parts of the viscerocranium? What are the membranous parts?
Cartilaginous: Structures from pharyngeal arches (see image)
Membranous: Maxillary prominence, squamous part of temporal bone, maxilla, zygomatic bone
What is the most common form of craniosynostosis?
Scaphocephaly (sagittal suture). Long, narrow, wedge shaped suture.
Brachycephaly is a premature closue of what suture?
The entire coronal suture
Plagiocephalyis a premature closue of what suture?
One side of the coronal suture
Trigonocephalyis a premature closue of what suture?
Frontal (metopic) suture
What are the 5 facial primordia? When do they appear?
2 Maxillary prominences
2 Mandibular prominences
1 Frontonasal priminence
They appear around week 4.
What are the nasal placodes?
Bilateral oval thickenings of surface ectoderm on the inferolateral portion of the frontonasal priminence. Forms the medial and lateral nasal prominences, which then forms the primordial nares.
Describe the development of the auricular primordia.
6 auricular hillcocks form around 1st pharyngeal groove. Development of the mandible pushes ears from neck to side of head at the level of the eyes.
What separates the primordial nasal sacs? When does it rupture?
The oronasal membrane. Ruptures in week 6.
What forms the primary palate?
Fusion of the two median nasal prominences
What forms the secondary plate?
Develops from the lateral palatine processes (palatal shelves)
What forms the nasal spetum?
Downward growth of internal parts of merged medial nasal prominences. Fuses with lateral palatine processess.
What are some of the risk factos for celft lip and palate?
Genetics: SATB2, TGF-alpha, TGF-beta, IRF6
Environmental: antiepileptic drugs, smoking, binge drinking, folate deficiency, obesity
What is choanal atresia?
Bony abnormalities of the pterygoid plates and midfacial growth abnormalities that can cause airway obstruction, noisy breathing, and cyanosis.
What forms the oral (anterior 2/3) portion of the tongue?
Median lingual swelling (median tongue bud) and 2 lateral tongue swellings (distal tongue buds)
What forms the pharyngeal portion of the tongue?
The copula (from PA 2) and the hypopharyngeal eminence (from PA 1). Hypopharyngeal eminence eventually overgrows copula.
What is glossoschissis?
A bifid tongue
What is ankyloglossia?
Short lingual frenulum. Can present with problems breast feeding and speaking.
What are the dental laminae?
U-shaped bands of oral epithelium that follows the curves of the primitive jaws.
What are the 3 main components of a tooth bud?
Enamel organ
Dental papilla
Dental follicle/sac
What is the enamel organ made of?
Ectodermal cells from the dental lamina
What is the dental papilla?
The internal part of the tooth bud. Eventually makes dentin and pulp.
What is the dental follicle/sac?
Mesenchyme surrounding dental papilla and enamel organ. Eventually makes cementum.
What occurs during the bell stage of teeth development?
Odontoblasts invade and calcifies predentin to become dentin. Ameloblasts are activated in response to dentin production and produces enamel. Enamel organ becomes bell shaped due to differentiation of enamel.
What forms the periodontal ligaments?
Outer cells of the dental sac
