oral histo week 1

• Sperm and ovum (fertilization), zygote (fertilized egg), morula (ball of cells), and blastocyst are the stages in the development of the oral facial region.
• Gastrula has two cavities divided by an embryonic disk and has three distinct cell layers: ectoderm (inner cavity) lined with ectodermal cells, endoderm (outer cavity) lined with endodermal cells, and mesoderm (outer cavity) lined with mesodermal cells.
• Facial malformations such as cleft lip and cleft palate may develop as a result of failure in fusion or closure of specific processes during face and palate development.
• Upper lips fuse (philtrum) during the 7th week of development.
• Left and right palatine processes grow medially as tongue grows downward during palatal development.
• Face appears more human during the 7th week of development.
• Palatal Development begins during the 7th to 9th week of development.
• Palate separates the oral cavity from the nasal cavity and has two parts: a primary palate located at the median nasal process and a maxilla proper located at the two lateral palatine processes.
• Orbicularis oris grows around the oral pit.
• Eyes are in front of the face and are in the same horizontal plane with the nostrils during the 7th week of development.
• Median nasal process is located median to the nasal pits.
• Median nasal process and maxillary process develop during the 7th to 9th week of development.
• Lateral nasal process is located lateral to the nasal pits.
• The 3rd pouch is the inferior parathyroids and thymus.
• Embryonic disk consists of mesodermal/mesenchymal cells which form the muscles, skeleton and blood cells.
• The oropharynx is the primitive oral cavity and pharynx.
• The heart is pushed beneath the brain creating a pit called the stomodeum or primitive oral cavity.
• During the 6th week, there is broadening of the face due to lateral growth of the brain, the eyes and maxillary process begin to come into the front of the face, the mouth slits widens, and the median nasal process and maxillary process fuse to form the upper lip.
• The 2nd pouch is the palatine tonsils.
• Pharyngeal arches or branchial arches are formed and they appear as bars of tissues at the side of the pharynx.
• The 5th pouch is the ultimobranchial body.
• The oral pit deepens to form the oral cavity, with the deepest extent known as the oropharyngeal membrane or buccopharyngeal membrane, which ruptures at the 5th week opening the oral cavity to the tubular gut.
• Pharyngeal pouches or branchial pouches are grooves that separate the arches within the pharynx.
• The face and the palate develop during the 4th week when the frontal processes of the maxillary arch bulge forward and laterally, the maxillary process develops as swellings of tissue from the mandibular arch below it, the mandibular arch appears divided or constricted, and the heart pumps blood throughout the body.
• At the 4th week of development, the human embryo appears like a flat disk and the brain expands and enlarges.
• The 5th week sees the nasal placodes thicken and develop into nostrils, the nasal pits open into the oral pit thus the frontonasal process is formed, the eyes become prominent at each sides of the head, and the mandibular arch loses constriction.
• The 1st branchial groove is the external auditory canal.
• The 4th pouch is the superior parathyroids.
• The 1st pouch is the middle ear and eustachian tube.