Development of face Flashcards
What is the face of the embryo made up of early in development?
Frontonasal prominence
1st pharyngeal arch
- maxillary prominence
- mandibular mandibular prominence
Stomatodeum
What is the stomatodeum?
Buccopharyngeal membrane
What happens to the buccopharyngeal membrane? Why?
Breaks down
because it is avascular, lacks blood supply
Where are the eyes located on the face of the embryo early in development?
Sides of the frontonasal prominence
What does the frontonasal prominence develop into?
Forehead
Bridge of nose, nose
Philtrum
What is the philtrum?
Ridge above the upper lip in the middle
What do the maxillary prominences develop into?
Cheeks
Lateral upper lip
Lateral upper jaw
What do the mandibular prominences develop into?
Lower lip
Jaw
What structures contribute to the development of the nose?
Nasal placodes, pits
Medial nasal prominence
Lateral nasal prominence
What is a placode?
Ectodermal thickening
differentiates to give rise to sensory tissue
What happens to the nasal placodes?
Sinks to form pits called the nasal pits
Where are the nasal placodes and pit located?
Frontonasal prominence
What is the medial nasal prominence?
Prominence medial to the nasal pit
What is the lateral nasal prominence?
Prominence lateral to the nasal pit
How does the nose develop?
Maxillary prominences grow towards each other
push the medial and lateral nasal prominences with them
medial nasal prominences fuse in midline
medial nasal prominence fuses with maxillary prominence
What does fusion of the medial nasal prominences form?
Intermaxillary segment
What is the intermaxillary segment made up of?
Philtrum
Upper jaw
Primary palate
How are the nasal and oral cavities initially related to each other during development?
Are continuous with each other
What happens to the initial relationship between the nasal and oral cavities during development?
They are completely separated
by the secondary palate
How does the secondary palate form?
Maxillary prominence gives off two palatal shelves
these grow vertically downwards on each side of tongue
tongue drops
the palatal shelves then grow towards each other
fuse in midline
Why does the tongue drop during development?
Mandible grows larger
increases space in oral cavity
What happens to the nasal cavity during development?
Separates into right and left nasal cavities
How is the nasal cavity separated into right and left nasal cavities during development?
Nasal septum in midline
grows downwards
fuses with palatal shelves
What is a cleft lip?
Opening in upper lip that may extend into nose
How does a cleft lip form?
Failure of fusion of medial nasal prominence and maxillary prominence
What is a cleft palate?
Opening in palate into the nose
How does a cleft lip and palate form?
Failure of fusion of medial nasal prominence and maxillary prominence
failure of fusion of palatal shelves
Where are the ears of the embryo initially located early in development?
Neck
What causes the ears to migrate from the embryonic neck to their normal position?
Growth of mandible
What is foetal alcohol syndrome?
Group of conditions that occur in person whose mother consumed significant amounts of alcohol during pregnancy
Why does alcohol affect the developing embryo/foetus?
Freely crosses placenta
affects migration of neural crest cells
development of brain
How does foetal alcohol syndrome affect the developing face? Why?
Affects the facial skeleton
because this is derived from neural crest cells migrating into the pharyngeal arches
What are the characteristic facial features of somebody with foetal alcohol syndrome have?
Small head
Flat midface
Smooth philtrum
Underdeveloped Jae
