Embryology Of The Face And Palate Flashcards
What are the three prominences that will transform into the face?
Frontonasal
Maxillary
Mandibular
What are the maxillary and mandibular prominences from?
The first pharyngeal (brachial) arch
What are placodes and what facial structures are derived from them?
A facial primordia
Ectodermal thickenings with neurological potential that appear in pairs on the developing head. Contribute components to the special senses
Three of them:
Lens
Otic (inner ear)
Nasal (nasal cavity and part of upper lip)
What are the facial prominences derived from?
Neural crest cells
Migrate into the pharyngeal arches
What is the frontonasal prominence?
Mesenchyme ventral to brain vesicles
Where is the maxillary prominence from?
Extension of the first pharyngeal arch
Where is the mandibular prominence from?
First pharyngeal arch mesenchyme
What is the stomodeum?
Depression in the ectoderm surrounded by five facial prominences. Future site of mouth
What does the surface ectoderm of the stomodeum form?
The floor of the oropharyngeal (buccopharyngeal) membrane
When does the oropharyngeal membrane break down and what does it form and where was it?
Day 24
Opens the primitive gut to the amniotic cavity
Membrane was located at the junction of the anterior 2/3 and posterior 1/3 of the tongue
Where do the facial primordia mostly migrate?
To the midline
What does the fromtonasal prominence form?
Midline structures of the face
- forehead, dorsal aspect of the nose
What do the medial and lateral nasal prominences form?
As elevations on the frontal nasal prominences around the developing nasal placodes/pits
Medial - migrate medially, fuse and form the inter maxillary segment, contributing to the midline of the nose and part of the nasal septum, philtrum of the upper lip, per maxillary part of the maxilla, and primary palate
Lateral - migrate to form the sides of the nose
What happens as the nasal pits deepen?
They move midline and fuse into the intermaxillary segment
What week does the nose obtain a more human shape?
8
What happens at the line of the maxillary and frontonasal prominence?
Surface ectoderm makes a cord in the nasolacrimal groove, undergoes apoptosis and becomes the lacrimal duct
What happens if the lacrimal duct does not open?
Chapped eyes
Infections
Will have to open
What is the progression of nasal placodes?
4.5 weeks nasal placodes - 6 weeks nasal pits - 7 weeks nasal sacs
What is the nasal sac?
Surface ectoderm
What is the oronasal membrane?
Separates the oral and nasal cavity
Breaks by apoptosis
What does the surface ectoderm of the nasal placodes form?
Diff into neural ectoderm and forms hair cells and nerves that go to the old
Factory bulb
What is choanal atresia?
Failure of the nasal cavity to open
What is the critical period of palate development?
Week 6 to the beginning of week 9
Where does the palate derive from?
Primary palate from the intermaxillary segment
Secondary palate from the palatine shelves of the maxillary prominences
Where does the incisive foramen mark?
Where the primary and secondary palates come together
What forms the palatine shelves?
He secondary palate
What are some anterior defects that are congenital abnormalities of the lip and palate?
Due to failure of fusion of the maxillary prominences with the fused medial nasal prominences
Cleft involving upper lip, alveolar part of the maxillar and primary palate
What are some causes of posterior defects of the palate?
Failure of the fusion of the palatine shelves with one another, nasal septum and with the posterior margin of the primary palate.
Involve hard and soft palate
What are facial features of fetal alcohol syndrome?
Indistinct philtrum
Flat mid face
Small jaws
Do you have sinuses at birth?
No. Maybe ethmodial
What helps jaw development?
Chewing
