QUIZ 1 Development of the Craniofacial Skeleton Flashcards Preview

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Flashcards in QUIZ 1 Development of the Craniofacial Skeleton Deck (59)
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describe the general composition of bone

  • hydroxyapatite formed on a collagenous matrix
  • non-collagenous proteins


name and describe the two types of bone growth processes

  • endochondral ossification
    • bone that is formed on a cartilage template
      • long bones
  • intramembranous ossification
    • bone that is formed from a condensation of mesenchyme
      • most of the mandible, skull plates


what is initiation?

start of ossification, whether conversion of cartilage to bone, or condensation and ossification of mesenchyme/neural crest


what is growth?

addition of more bony matrix to a pre-existing bone; thickening, elongation, etc.


what is primary displacement?

  • movement of a bone due to its own growth
  • can occur in either direction, depending on the ratio of resorption to deposition and other structures
  • bones often move in the opposite direction from which they are depositing matrix, as is often the case in articular surfaces and joints


what is secondary displacement?

  • movement of a bone due to the growth of other bones


what is remodeling?

  • growth involving simultaneous deposition and resorption on all peri- and endosteal surfaces
  • changes size, shape, proportion, relationship with adjacent structures


what is drift?

remodeling that results in movement of a bone towards the deposition surface


what is functional matrix?

a tissue that guides a bone's growth by exerting a force upon the bone


describe directional bone growth 

  • can occur by the deposition of bone on a surface, with concomitant resorption on another
    • typically asymmetric growth so as to maintain some proportion
    • some surfaces grow more than others, and some undergo resorption more than others
    • deposition and resorption rates at a surface can change over time and even switch
  • can occur at the endosteal or periosteal surfaces


describe an example of bone growth as a result of a combination of primary and secondary displacement

distal phalanges grow directionally (primary displacement), but most of the movement is due to growth of long bones of the arm (secondary displacement)


directional bone growth

what is a growth field?

where matrix can be laid down or resorbed


directional bone growth

what are growth sites?

fields of significance to growth of a bone (ex. mandibular condyle, maxillary tuberosity)


directional bone growth

 what are growth centers?

special growth sites, control overall growth of bone (epiphyseal plates of long bones)


what is the neurocranium?

  • the bones encasing the brain
  • consists of the calvaira and cranial base


describe the calvaria

  • "skull cap"
  • intramembranous bone
  • both paraxial mesoderm and neural crest in origin
  • also called the desmocranium


describe the cranial base

  • base of the skull
  • derived from special sense organ capsular tissues
  • endochondral bone, primarily neural crest
  • early form called chondrocranium


what is the viscerocranium?

  • derived from pharyngeal arches
  • consists of what is considered the face (anterior, lower skull)


how many bones make up the facial skeleton? what are they?

  • 14
  • 2 nasal bones
  • 2 lacrimal bones
  • 2 inferior nasal conchae
  • 2 maxillae
  • 2 palatine bones
  • 2 zygomatic bones
  • 1 vomer
  • 1 mandible


describe postnatal growth of the skull

  • the skull does not grow equally in all directions or regions
  • this is of interest to the dentist
    • the viscerocranium grows much more postnatally than the desmocramium


what bones make up the calvaria/desmocranium?

frontal, parietal, parts of the occipital, temporal, and sphenoid bones


what type of ossification is the desmocranium/calvaria formed?

intramembranous ossification


the calvaria/desmocranium

condensed ___ forms a bilayer membrane that encapsulates the developing ___

  • mesenchyme
  • brain


describe the bilayer membrane formed by condensed mesenchyme

  • inner layer (endomeninx)
    • neural crest, gives rise to the pia mater and arachnoid mater
  • outer layer (ectomeninx)
    • neural crest and paraxial mesoderm, gives rise to dura mater and calvaria/bone


what ossifies to form the frontal bones and parietal bones?

superficial ectomeninx in the cranial vault


which layer remains unossified and forms the dura mater?



the various bones of the skull are initially held together by ___



what are sutures?

mesenchymal gaps between bones of the calvaria


what are fontanelles?

unossified sutures between 2 or more skull bones


___ and ___ allow for growth of the skull to make room for more brain

sutures and fontanelles