Orofacial

• How long after conception does folding of the embryo begin?

  After 3 weeks of intrauterine life
• In which directions does the embryo fold?

  Along the rostrocaudal and lateral axis
• What is critical for the formation of the stomatodeum?

  The head fold
• What is the stomatodeum?

  A depression between the brain and cardiac bulge
• What does the stomatodeum become?

  The precursor of the mouth
• What are the prominences involved in facial development around the stomatodeum?

  • Frontonasal prominence
  • Maxillary prominences (2)
  • Mandibular prominences (2)
• When does face development begin?

  At approximately 3rd to 4th weeks
• What forms the frontonasal prominence?

  A slightly rounded elevation cranial to the stomodeum
• When does the frontonasal prominence appear?

  Day 24
• When do the maxillary prominences appear?

  Day 26
• What do the maxillary and mandibular prominences derive from?

  First pharyngeal arch
• What does the frontonasal prominence derive from?

  Developing forebrain
• What develops from the frontonasal prominence?

  Medial and lateral nasal prominences
• When do the nasal/olfactory placodes appear?

  Day 27
• What forms the alae of the nose?

  Lateral nasal prominences
• What do the medial nasal prominences fuse to form?

  Middle of the nose and philtrum
• What do the maxillary prominences form?

  Upper cheek regions and upper lip
• What do the mandibular prominences form?

  Chin, lower lip, and lower cheek regions
• What happens to the maxillary prominences during development?

  They increase in size and grow medially
• What occurs between the medial nasal prominence and the maxillary prominence?

  The cleft is lost and they fuse
• What unusual fusion occurs between the maxillary and lateral nasal processes?

  Formation of the nasolacrimal duct
• What does the nasolacrimal duct connect?

  Medial corner of the eye to nasal cavity
• When does the face develop during gestation?

  Between 24 and 38 days
• What is the primary palate formed by?

  Fusion of two medial nasal processes
• What is the secondary palate formed by?

  Fusion of two palatal shelves from maxillary processes
• What is the final palate formed by?

  Fusion of all processes
• What happens to the lateral palatine processes during tongue development?

  They ascend to a horizontal position
• What is the main factor in the closure of the secondary palate?

  Displacement of the tongue from palatine shelves
• When does fusion with the nasal septum begin?

  During the 9th week
• What happens to epithelial cells during fusion of the secondary palate?

  They transform into mesenchymal cells
• What forms the hard palate?

  Bone develops in the anterior part
• What happens to the nasal pit during development?

  It deepens due to growth of nasal prominences
• What separates the nasal pits from the primitive oral cavity initially?

  The oronasal membrane
• What forms the definite choanae?

  Breakdown of the oronasal membrane
• What is the primary function of the tongue?

  Manipulates food for mastication
• What covers the upper surface of the tongue?

  Taste buds housed in lingual papillae
• What is a major function of the tongue in humans?

  Enabling speech
• From which arch does the anterior two-thirds of the tongue develop?

  First pharyngeal arch
• What are the three swellings that form the anterior two-thirds of the tongue?

  Two lingual swellings and one tuberculum impar
• What is the role of the tongue in the digestive system?

  It helps in the act of swallowing