Development of the Craniofacial Skeleton Flashcards Preview

Oral Biology > Development of the Craniofacial Skeleton > Flashcards

Flashcards in Development of the Craniofacial Skeleton Deck (48):
1

what is bone made of?

hydroxyapatite formed on a collagenous matrix, with various attendant non-collagenous proteins

2

endochondral bone

bone that is formed on a cartilage template
eg: long bones

3

intramembranous bone

bone that is formed from a condensation of mesenchyme
eg: most of mandible, skull plates

4

initiation

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

5

growth

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

6

primary displacement

movement of a bone due to its own growth

7

secondary displacement

movement of done due to growth of other bones

8

remodeling

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

9

drift

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

10

functional martix

a tissue that guides a bones growth by exerting a force upon the bone

11

bone growth can occur in either direction, it just depends on what?

the ratio of resorption to deposition and other structures

12

growth fields

where matrix can be laid down or resorbed

13

growth sites

fields of significance to growth of a bone
eg: mandibular condyle, maxillary tuberosity

14

growth centers

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

15

what is considered the neuroncranium?

the brain pan( basically the bones encasing the brain)

16

neuroncranium: calvaria

skull cap
*intramembranous bone
*paraxial mesoderm and neural crest origin
also called the desmocranium

17

neurocranium: cranial base

the base of the skull
**endochondral bone, primarily neural crest
-early form called chondrocranium

18

what is the viscerocranium?

the facial skeleton

19

what is the viscerocranium derived from

pharyngeal arches

20

what part of the skull grows more postnatally?

viscerocranium more than the desmocranium

21

what bones make up the calvaria aka the desmocranium?

frontal, parietal, parts of occipital, temporal, sphenoid bones
**remember it is form intramembranously

22

what is the endomeninx?

the inner layer of the calvaria,
-made of neural crest, and gives rise to pia mater and arachnoid mater

23

what is the ectomeninx?

outer layer of the calvaria
-made from neural crest and paraxial mesoderm, and gives rise to the dura mater and the calvaria/bone

24

sutures

mesenchymal gaps between bones of calvaria

25

fontanelles

un-ossified suture between 2 or more skull bones

26

what marks the end of bone growth of the calvaria

ossification of sutures

27

what is anencephaly?

failure of rostral neural tube to close
*results in the loss of telencephalon

28

what is craniosynostosis

premature fusion of the cranial vault sutures

29

bones of the cranial base aka chondrocranium

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

30

why does the chondrocranium form via endochondrial ossification and not intramembranous ossification?

ectomeninx in floor of brain forms cartilage in response to notochord and other epithelial signals, becomes chondrocranium, later undergoes endochondral ossification

31

what is the embryological tissue that forms the nasal cavity?

nasal capsule

32

what part of the nasal capsule does not ossify?

the nasal septal cartilage, this plays a large role in the downward/ forward growth of midface

33

what happens as the chondrocranium grows?

it pushes the maxilla and the rest of the facial skeleton down and forward

34

maxilla proper

intramembranous ossification of mesenchyme, forms from maxillary prominence/process

35

premaxilla

intramembranous ossification of mesenchyme, forms from frontonasal process, forms primary palate, fuses with maxilla proper

36

secondary cartilages

zygomatic process, alveolar plate, hard palate between palatine processes-mostly fetal growth roles

37

the ossification center of the maxilla is associated with what cartilages?

nasal capsule
zygomatic or malar cartilage

38

the alveolar plates form from what?

the forming maxilla and the junction of the palatal process and houses the tooth germs

39

the maxilla forms and grows down and forward via?

primary and secondary displacement from the growth of the zygomatic and nasal septum cartilages

40

how does the mandible form in terms of bone growth

intramembranous ossification
**forms lateral to Meckel's cartilage (hyaline)

41

what is the direction of ossification spread of the mandible?

posteriorly to form the body and ramus
anteriorly Meckel's cartilage largely disappears and does not become the mandible proper

42

what are the secondary cartilages that form from Meckel's cartilage?

condylar, coronoid, and symphyseal

43

why is the condylar cartilage important?

it extends into a cone running along the ramus and ossifies through endochondral ossification.
*condylar cartilage remains at the articular ends on the head

44

T/F the mandible is both membranous and endochondral in nature?

true

45

the cartilage of the mandible is not primary (Meckel's) it is what kind?

secondary (derivatives)

46

coronoid cartilage

disappears before birth, contribute -transiently to growth and development of the surround tissues

47

symphyseal cartilages

disappear in the first year of birth
-transiently to growth and development of the surround tissues

48

Condyle cartilage

important growth center for the ramus
does intramembranous ossification and then ossifies itself through endochondral ossification
* functions both in articulation at TMJ and in growth