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What cell lineage is responsbile for the branchial arches?
Neural crest cells
primary palate 5 weeks
secondary palate 7 weeks
When does branchial arch development appear?
What cells contribute to formation of the facial skeleton?
Neural crest cells
What are the arches?
- 1: V2 and V3
- 2: VII
- 3: IX
- 4: X, superior laryngeal
- 6: X, recurrent laryngeal
What do the pharyngeal pouches form?
Five mesenchymal prominences appear at week 4:
What forms the nasolacrimal duct?
Merging of maxillary prominence and the lateral nasal prominence
What forms the philtrum, premaxilla, and the incisors?
median nasal prominence, forms the intermaxillary segment
What forms the nasal septum?
The frontal prominence
What factors are involved in lip fusion?
SHH, MSX1 and MSX2, BMP and FGF
When and from what does the definitive palate form?
6 weeks, from the maxillary prominence (palatine shelves)
7 weeks, begin fusion with primary palate
The development of the skull is divided into?
- 1. Neurocranium: membranous and chondrocranium
- 2. Viscerocranium: skeleton of the skull
Intramembranous ossification of bone is completed by which bones?
Face, vault, mandible, clavicle, distal tips of phalanges
Endochorondal ossification is completed by which bones?
The rest of the skull
In endochondral ossification where is primary center and secondary center?
Secondary: proximal and distal epiphyses
What are the steps in endchondral ossification?
When does the frontal bone (metopic suture) close?
Begins 2 years, fused by 8-12 years
When does symphysis menti fuse?
When does the spheno-occipital synchondroses fuse?
When does the spheno-ethmoidal synchondroses fuse?
Which bones form from the neural crest cells (blue) and which from paraxial mesoderm (red)?
What are the layers of the membranous neurocranium?
1. Endomeninx (inner layer): neural crest origin and forms the pia and arachnoid mater
2. Ectomeninx (outer layer): neural crest and mesoderm and forms dura mater, calvaria, pericranium
Bony ossification centers and appearance during fetal development?
- 1) 2 months: frontal, parietal, occipital, sq. temporal
- 2) 3 months: tympanic ring
What are the four fontanels?
- a. Anterior (bregmatic): largest, persists til 2yrs of age
- b. Posterior (lambda): triangular, persists 2months
- c. Sphenoidal: smaller, persists 3 months
- d. Mastoidal: smaller, persists 2 years
What are the functions of the sutures?
1. sites of bone growth
2. articulations, minor movements for birthing
3. mechanical shock absorber
What is the life cycles of a suture?
1. Presumptive: undiff, wide
2. Definitive: well diff, narrow, interdigitated
3. Fusing: collagenous bundles then bony spicules, eventually obliterate
What signals to the sutures for them to progress through cycle?
- 1. Pericranium
- 2. Periosteum
- 3. Bone (osteogenic fronts)
- 4. Dura mater
What factors regulate the suture?
BMPs, FGFs, TGFBs, TWIST
How many arches comprise the tongue?
4 (1-4) appears 4 weeks in development
What arch forms the epiglottis?
In development how does the thyroid gland form?
Epithelial proliferation between tuberculum impar and the copula
Tooth development begins?
- Cap: ODE, IDE, Stellate recti, Dental papilla
- Bell: Dentin, Enamel form