Development of face and palate

Face

5 processes formed by proliferation of neural crest cells (ectoderm)

These cells migrate from mesencephalon and rhombencephalon into arches

  • 1 frontonasal process – cranial to stomodeum
  • 2 maxillary processes – lateral, from 1st pharyngeal arch
  • 2 mandibular processes – caudal, from 1st pharyngeal arch

 

1 frontonasal process:

  • 2 nasal placodes develop
  • Each invaginated to form:
  1. Nasal pit – forms nasal cavities – open in pharynx posteriorly
  2. Lateral nasal fold – ala of nose
  3. Medial nasal fold – fuse together to form:
  • Surface: middle part of nose, filtrum of upper lip
  • Deep: anterior upper jaw with Incisor teeth, primary palate with incisive fossa

NB: Also forms nasal septum

2 maxillary processes:

  • Grow medially
  • Fuse with medial nasal fold – form upper lip
  • Fuse with lateral nasal fold – form nasolacrimal duct
  • Fuse with mandibular process – forms cheeks
  • Forms palatine shelves

2 mandibular processes:

  • Fuse with each other medially – form lower lip and chin
  • fuse with maxillary process – forms cheeks

NB: Degree of fusion of max. and mand. processes determine width of mouth

 

Image result for development of face


 

Palate

Origin: Neural crest cells (ectoderm)

  • Formed by primary and secondary palate
  • Primary palate formed from frontonasal process (fusion of medial nasal folds)
  • Secondary palate formed from 2 palatine shelves, which arise from maxillary process
  • 2 palatine shelves fuse with each other medially, and primary palate anteriorly
  • Nasal septum descends downwards and fuses with palate in midline
  • Anterior part of palate ossifies and posterior part remains fleshy to form hard and soft palate

 

Anomalies of face and palate:

  1. Inclusion dermoid – cystic swellings around lines of fusion of face
  2. Macrostomia – large mouth, incomplete fusion between max. and mand. processes
  3. Microstomia – small mouth, excessive fusion between max. and mand. processes
  4. Oblique facial cleft – failure of fusion between maxillary and frontonasal process
  5. Lateral cleft upper lip – unilateral or bilateral
  6. Cleft palate – unilateral, bilateral, only soft palate or cleft uvula

 

 

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