Head And Neck Session 3 Flashcards
What does the facial skeleton arise from?
Neural crest cell infiltration of the mesenchyme core of PA1
Where do the muscles of mastication originate from?
Mesoderm of PA1
Where do the muscles of facial expression arise from?
Mesoderm of PA2
What are neural crest cells?
Specialised population of cells that originate in the neuroectoderm upon induction by the neural tube (4th germ lineage)
What happens to neural crest cells at the lateral border after being induced by the neural tube?
Displace and ente mesoderm instead of becoming CNS. Then migrate throughout body to give rise to many structures
What are the external features that derive from the FNP?
Forehead, bridge of nose, nose and philtrum
What is located at the base of the stomatodeum?
Buccopharyngeal membrane
What is the external feature that derives from the stomatodeum?
Oral fissure
Where do the cheeks, lateral upper jaw and lip derive from?
Maxillary prominence of PA1
What arises from the mandibular prominence of PA1?
Lower lip and jaw
Describe the process of formation of the nose.
Nose placodes appear on FNP and sink to form nasal pits –> medial and lateral prominences on either side of pit are pushed together by maxillary prominence moving medially –> maxillary fuse with medial nasal –> medial prominences fuse in the midline
What does fusion of the medial nasal prominences create?
Intermaxillary segment consisting of labial component, philtrum, upper jaw, 4 incisors and primary palate
What is the main part of the definitive palate?
Secondary palate
Where is the secondary palate derived from?
Palatial shelves of maxillary prominences
How is the secondary palate formed?
Palatal shelves grow vertically downwards into oral cavity either side of tongue –> mandible enlarges –> tongue drops –> palatal shelves fuse in the midline
What initially separates the nasal pit and oral cavity but quickly degenerates?
Oronasal membrane
How does the nasal septum form?
Mid-line down growth that fuses with palatal shelves
What is the cause of lateral cleft lip?
Failure of fusion of medial nasal prominence and maxillary prominence
What is the cause of lateral cleft lip involving the primary palate?
Failure of fusion of medial nasal prominence and maxillary prominence
What is the cause of cleft lip and cleft palate?
Failure of fusion of medial nasal prominence and maximally prominence combined with failure of palatal shelves to meet in the midline
What are the consequences of cleft lip and left palate?
Difficulty suckling and with speech
What is the fate of the FNP?
Forehead, bridge of nose and medial and lateral nasal prominences
What is the fate of the medial nasal prominence?
Philtrum, primary palate and mid upper jaw
What is the fate of the lateral nasal prominence?
Sides of the nose