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Description
Flashcards by Evian Chai, updated more than 1 year ago
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Created by Evian Chai
about 4 years ago
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| Question | Answer |
| What are the 3 regions of the craniofacial complex? | 1. cranial vault 2. lower jaw 3. upper jaw |
| In a baby's head, how many fontanelles are there? What is the ratio of the cranial vault:face? | 6 fontanelles 8:1 |
| Rank the following in terms of growth rate from fastest to slowest: 1. Skull, eyes, inner/middle ear, brain 2. Face, body 3. Cranial base | Skull, eyes, inner/middle ear, brain>Cranial base (NEURAL rate first then somatic)>Face, body |
| What endochondral bones are present in the skull? | Cranial base Pharyngeal arch cartilage Octic/nasal capsule |
| What is the difference between endochondral and membrane bone in terms of formation and function? | Endochondral bones form in cartiledge first then ossify; are STRUCTURAL Membrane bone comes straight from cells going into osteoblasts; forms secondary cartilage in response to TENSION/STRESS |
| Where is membrane bone located in the skull? | Clavicle outside of head |
| What cells give rise to the face? | Cranial neural crest cells |
| What cells give rise to the cranial vault/base? | Mesoderm cells under neural crest |
| What three types of primary cartilage growth occurs post natally in terms of 1. Basi-occipital/basi-sphenoid and nasal septum 2. Growth plates 3. Remodelling | 1. Synchrondosis between basi-occipital/basi-sphenoid and nasal septum 2. Growth plates undergoing interstitial (at ends) growth 3. Remodelling with appositional (width) growth |
| What three types of membrane bone growth occurs in the facial/cranial vault? | 1. Growth of sutures 2. Surface deposition/remodelling by osteoblast/clasts 3. Secondary cartilage growth eg. Condylar cartilage |
| What are the steps of cranial vault development? | 1. Mesenchymal cells become osteoblasts that produce matrix 2. Bones grow/ossify, meet at sutures 3. Sutural cells ossify and grow 4. Displacement, brain pushes sutures apart 5. At the same time, remodelling as bones flatten to accommodate brain |
| What causes Microcephaly (brain defect)? | Zika virus |
| What do the prechordal, hypophyseal and parachordal cartilaginous precursors fuse to become? | The occipital, sphenoid and ethmoid bone |
| What are the 2 mechanisms of cranial base growth? | Cartilaginous growth at growth plates - Intersphenoid synchondrosis (birth) - Speno-ethmoidal synchondrosis (3-5 yrs) - Spheno-occipital synchondrosis (12-16 yrs) Remodelling that moves cranial base and face anteriorly and inferiorly |
| What form of growth is present in the sphenooccipital synchondrosis? What are the 4 zones? What cell is responsible? | Bidirectional endochondral growth with progenitor zone, proliferative zone, hypertrophic zone, and replacement bone Chrondocytes |
| What are 3 consequences of cranial base defects? | 1. No space for 3rd molars 2. Underdevelopment (eg. achondroplasia, Down's syndrome) 3. Class 3 occlusion |
| What type of cartiledge is Meckel's Cartilage, and what does it do? | Transient endochondral cartilage Supports the downward growth of the lower jaw |
| What are the steps of mandible development? | 1. Meckle's cartilage forms 2. Membrane bone ossifies around M. cartilage 3. M. cartilage disintegrates 4. Secondary cartilage forms in periosteum of membrane bone 5. Remodelling moves condylar/coronoid process back, lengthens mandible |
| What does Meckle's cartilage give rise to? | Malleus/Incus bone Perichondrium of sphenomandibular/sphenomalleolar ligaments |
| What 3 types of secondary cartilage are present? | 1. Condylar cartilage 2. Coronoid (disappear by birth) 3. Symphysial (unites mandible) |
| What are unique features of secondary cartiladge? | 1. Much more disorganised 2. Growth is quicker 3. Prechondrocytes not surrounded in matrix 4. fibrocartilage VS. hyaline |
| What are the 5 layers at the secondary cartilage growth plate? | 1. Periosteum (undifferentiated) 2. Prechondroblastic 3. Chondroblastic 4. Hypertrophic 5. Zone of bone formation |
| What are the 4 mechanisms of mandible growth? | Remodelling at anterior border of ramus Growth of secondary cartilage - Condylar cartilage - Symphysial cartilage - Coronoid cartilage Size difference between deciduous molars and their successors - premolar Forward movement of teeth through alveolar bone |
| What is the only endochondral bone in the upper jaw? | The Nasal septum |
| What are the 4 mechanisms of growth in the Maxilla bone? | Sutural growth and remodelling of maxilla and development of maxilla sinus Endochondral growth of septal cartilage (nasal septum/ethmoid) Addition of bone at tuberosity that makes room for permanent molars - Develops in alveolar bulbs at back of maxilla Teeth move forward as deposition on outer surface and resorption on inner surface increases size of maxilla bone |
| Is the cranial base endochondral or membrane bone? | Endochondral Bone |
| Is the cranial vault endochondral or membrane bone? | Membrane Bone |
| What are the 2 mechanisms of cranial vault growth? | Suture Growth and remodelling |
| What are 2 limitations in growth of the upper face? | 1. At year 1, metopic suture unites+great wings/body of sphenoid ossifies limiting width 2. At year 3 Cribiform plate of ethmoid unites |
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