15 - Head + Neck - Development (Face + Midline structures) Flashcards
Define placode:
An area of ectoderm in the embryonic head which begins to thicken and differentiate itself from the surrounding tissue
Ex: lens, nasal and otic placodes of the developing face
What are the main complications of a cleft lip + palate?
- Inability to suckle/feed
- Impaired speech development
A cleft lip is the failure of fusion of which structures?
- Median nasal prominence
- Maxillary prominence
A cleft palate is the failure of fusion of which structures?
Secondary palatal shelves (maxillary prominences)
Why does alcohol have such a profound effect on the developing head and neck of an embryo?
It kills neural crest cells and affects their migration and subsequent brain development
What are the symptoms of Foetal Alcohol Syndrome?
- Microcephaly
- Epicanthal folds
- Small eye openings
- Short nose
- Smooth philtrum
- Underdeveloped jaw
What happens to the pharyngeal clefts in the developing embryo?
2nd pharyngeal arch grows down and obliterates the clefts below, such that only the 1st cleft remains (= EAM)
Where do branchial cysts occur?
Anterior border of SCM
How does a branchial cyst develop?
Formed if the 2nd pharyngeal cleft is not obliterated completely by the 2nd pharyngeal arch during development
How many deciduous and permanent teeth are there, and when do they begin to erupt?
20 deciduous teeth ~ 6-30 months
28 permanent teeth (+ wisdom = 32) ~ 6-13 yrs
What is Rathke’s pouch?
Invagination of ectoderm which forms the anterior pituitary
What tissue does the anterior pituitary derive from?
Ectoderm
What tissue does the posterior pituitary derive from?
Neuro-ectoderm
What causes Rathke’s pouch to be pinched off from the ectoderm?
Ossification of the sphenoid bone
How is the tongue attached to the floor of the mouth?
via the Lingual frenulum
