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25 Cards in this Set
- Front
- Back
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Place the following events in order:
-Palatal shelf elevation -Fusion of the mandibular processes -Neural tube formation -Closure of the cranial sutures -Embryonic folding -Formation of the trilaminar embryo -Branchial arch formation |
1. Formation of the trilaminar embryo
2. Neural tube formation 3. Embryonic folding 4. Branchial arch formation 5. Fusion of mandibular processes 6. Palatal shelf elevation 7. Closure of cranial sutures |
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ID the germ layer of origin for the following structures:
-Ms. of mastication -Lining of gut -Enamel -Lining of ear canal -Oral mucosa |
-Ms. of mastication - mesoderm
-Lining of gut - endoderm -Enamel - ectoderm -Lining of ear canal - ectoderm -Oral mucosa - ectoderm |
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In which weeks does craniofacial development occur?
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4th thru 12th weeks
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Cleft lip caused by?
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Incomplete (true) fusion of maxillary process of mandibular arch with medial nasal processes
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Neural crest cells:
-Origin -Location at early 2nd/late 3rd week |
-Origin: neuroectoderm
-Location: mesoderm *failure can result in treacher-collins syndrome where mandible is very underdeveloped |
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Neural Tube:
-Formed by? -Forms? -Time frame of neurulation? |
-formed by folding in of ectoderm cells
-forms spinal cord/brain -occurs be end of 3rd week *failure of neural tube closing is associated with folic acid deficiency |
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Cleft palate caused by?
-Time frame? |
Incomplete (true) fusion of palatal shelves (often caused by tongue not moving out of the way).
Fusion of shelves occurs at week 9. |
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Define:
Teratogen |
Teratogen – agents that cause developmental defects (inc. x-rays, drugs, alcohol, infectious agents, nutritional deficiencies/ excesses)
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Define:
Notochord |
Notochord – a rod-shaped body that is composed of cells derived from the mesoderm; its function is to provide support for the embryo and to induce the overlying ectoderm to specialize and undergo neurulation (so that the neural tube can be formed)
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Define:
Stomodeum |
Stomodeum – depression in the embryo that is the precursor of the mouth
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Define:
Ectomesenchyme |
Ectomesenchyme – the embryonic connective tissue that is critical for craniofacial development; forms from the migration of neural cells from the ectoderm into the mesoderm
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Place the following events in order:
-Embryonic folding -Neural tube closure -Formation of the trilaminar disc -Fusion of the mandibular processes |
formation of trilaminar disc, neural tube closure, embryonic folding, fusion of mandibular processes
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Germ layer of origin for following:
-Dentin -Meckel's cartilage -Lining of oral cavity -Bone of mandible |
-dentin: neural crest cells
-Meckel's cartilage: neural crest cells -lining of oral cavity: ectoderm -mandible: neural crest cells |
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Origin of Mandibular Processes
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branchial arch 1 (maxillary processes and meckel's cartilage also from this arch)
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Function of Meckel's Cartilage
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it is a bar of cartilage that induces the formation of the mandible and serves as scaffolding for the formation of the mandible
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Craniofacial Development:
Week 7 |
-initiation of mandible formation: intramembranous ossification of body of mandible lateral to meckel's cartilage
-also, intramembranous ossification of facial bones begins |
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Craniofacial Development:
Week 10 |
palatal shelves have elevated and fused; apoptosis is occurring to eliminate the seam of epithelial tissue (ectomesenchyme) that needs to be replaced by bone at the midline
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Craniofacial Development:
Week 12 |
-appearance of condylar cartilage, which serves as a growth site for the mandibular condyle of TMJ - superior condylar process formed by replacement of cartilage with bone & inf. condylar proc. forbed thru intramembranous ossification
-also meckel's cartilage is shrinking |
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Craniofacial Development:
Week 13-14 |
formation of joint space at TMJ
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Craniofacial Development:
Week 16 |
functional jaw movements are possible
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Craniosynostosis caused by?
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premature fusion of cranial sutures
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Intramembranous Ossification:
-Define -Where does it occur in mandible devel.? |
-de novo initiation, production of matrix, & ossification w/in ectomesenchyme
-occurs in body of mandible lateral to meckel's cartilage, facial bones, inferior condylar process formation |
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Endochondral Ossification:
-Define -Where does it occur in mandible devel.? |
-replacement of cartilage by bone
-occurs in superior condylar process formation |
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TMJ:
-Articular surfaces? Covered with? |
condyle, disk, & temporal bone covered with fibrous connective tissue
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Differences b/w the TMJ and other Synovial joints
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-TMJ has fibrous connective tissue covering articular surfaces as opposed to hyaline cartilage
-TMJ has articular disc separating an upper and lower compartment -TMJ undergoes late embryogenesis -TMJ has a hinge-sliding fxn (translation of condyle on temporal bone when mouth opens wide) |
