Concepts of Grown and Development pt 1

Question 1

what is the growth theory of bone?

Answer 1

primary determinant of its own growth and other tissues respond indirectly or epigenetically

Question 2

what is the growth theory of cartilage?

Answer 2

primary determinant of skeletal growth. Bone responds passively and secondarily

Question 3

what is the growth theory of soft tissue matrix?

Answer 3

primary determinant of growth is embedded in the skeletal elements .
both bone and cartilage are secondary
followers.

Question 4

what is the major difference in growth theories?

Answer 4

location where genetic control is expressed

*either periosteum, inside cartilage, or throughout the soft tissues

Question 5

growth is influenced by what 2 things?

Answer 5

genetics and environment

Question 6

what is the role of the genetic blue print model in regards to jaw growth

Answer 6

genetic preprogramming has been presumed by many to have a fundamental influence in establishing basic facial pattern.

Question 7

what is the current thinking regarding genetic tissues like the mandible size and/or skeletal malocclusion?

Answer 7

genetic tissues do not actually govern their own function, but are rather controlled by epigenetic (indirect) influences..

*from other tissue groups and developmental input signals

Question 8

If cartilage and cartilaginous growth were the primary influence in growth of the mandible, what would happen?

Answer 8

, the cartilage on the condyle of the mandible could be considered as a pacemaker for growth.

Question 9

are the mandibular condyles growth sites or growth centers?

Answer 9

growth sites

Question 10

why do bioelectric signals occur?

Answer 10

distortions of the crystals in bone

**cause minute deformation of bone matrix due to mechanical strain

Question 11

where are bioelectric charges generated?

Answer 11

area of deformation

Question 12

Altered electrical potentials appear to relate, directly or indirectly, and trigger what?

Answer 12

Osteoblasts and clasts

Question 13

what is Wolff’s law?

Answer 13

bone in a healthy person or animal will adapt to the loads under which it is placed

*theory developed in late 1800s

Question 14

what is the mechanostat theory??

Answer 14

• bone growth and bone loss is stimulated by the local mechanical elastic deformation of bone.
• bone adapts its mechanical properties according to the needed mechanical function – bone mass, bone geometry and hence bone is adapted according to the every-day usage / needs.

Question 15

T/F mechanostat theory is linear

Answer 15

true

Question 16

what make mechanostat theory so important?

Answer 16

especially for bone loss situations like in osteoporosis because forces on bone from muscle can stimulate bone growth and minimize/prevent bone loss

Question 17

what 3 areas support the theory that master growth centers control development?

Answer 17

Sutures, Condyles, and Synchondroses

**this was proven untrue. “It is clear now that sutures, and the periosteal tissues more generally, are not primary determinants of craniofacial growth”

Question 18

Why is the master growth center theory incorrect?

Answer 18

because growth at the sutures would occur largely independently of the environment

Question 19

what growth process relies on production of new bone cells to be recruited into bone fronts, while ensuring the cells within a suture remain undifferentiated?

Answer 19

growth at sutures

Question 20

how is sutural growth different than endochondral growth?

Answer 20

endochondral growth has chondrocyte hypertrophy, sutures do NOT have intrinsic growth potential

**sutures produce new bone at the sutural edges of the bone fronts in response to external stimuli

Question 21

what is unique about synchondrosal growth?

Answer 21

independent growth potential and are comparable to epiphyseal plates

Question 22

why is synchondroses being genetically coded important?

Answer 22

it dictates craniofacial growth and that it will develop even in the absence of functional activity

Question 23

what is a growth site?

Answer 23

simply a location where growth occurs

Question 24

what is a growth center?

Answer 24

a location where independent growth occurs regardless of what adjacent structures do

**genetically controlled

Question 25

what 2 growth sites are in the craniofacial complex?

Answer 25

1-sutures | 2-condyles

Question 26

what growth center is part of the craniofacial complex?

Answer 26

synchondroses

Question 27

T/F Primary and secondary cartilages differ in embryonic origin and in histological organization, and are generally considered to have a different mode of growth

Answer 27

True

Question 28

what does primary cartilage react to?

Answer 28

systemic growth stimuli such as hormones

Question 29

what does secondary cartilage react to?

Answer 29

follows overall stimuli after additional modulation by local growth factors

Question 30

growth centers contain what type of cartilage?

Answer 30

primary

Question 31

growth sites contain waht type of cartilage?

Answer 31

secondary

Question 32

is the nasal septum a growth center or growth site?

Answer 32

center

Question 33

What significant role does the nasal septum play in craniofacial growth and development?

Answer 33

displaces the maxilla downward and forward

Question 34

growth can refer to both size and?

Answer 34

any general change

Question 35

what word means an increasing degree of organization, complexity or specialization?

Answer 35

development

Question 36

the concept of pattern refers to what 2 things?

Answer 36

1- a set of proportional relationships at a point in time | 2-change of these proportional relationships over time

Question 37

in the third month in utero, the head takes up how much body length?

Answer 37

50%

Question 38

what part of the body shows the most growth during post natal development?

Answer 38

lower limbs followed by upper *reflects cephalocaudal gradient growth

Question 39

based on cephalocaudal growth (growing at the top down) what part of the face develops last?

Answer 39

mandible tends to grow more later in life

Question 40

why are growth charts showing percentiles better than classifying someone with normal or abnormal growth?

Answer 40

people and body parts grow and develop in a range of times

Question 41

what is the average peak growth for girls and boys?

Answer 41

girls 12 | boys 14

Question 42

general rule for growth spurt and height?

Answer 42

the earlier the growth spurt the shorter the duration of growth will be

Question 43

Hypertrophy

Answer 43

– Is an increase in the size of individual cells

Question 44

Hyperplasia

Answer 44

Is an increase in the number of cells. *prominent feature of all forms of growth

Question 45

Cells Secrete extracellular material

Answer 45

contribution to an increase in size independent of the number or size of the cells themselves

Question 46

by what method does soft tissues grow?

Answer 46

hyperplasia and hypertrophy ***interstitial growth***

Question 47

what is interstitial growth?

Answer 47

growth can occur at all points

Question 48

how does appositional growth occur?

Answer 48

by the recruitment of fresh cells and adds new matrix to the surface **cartilage does this

Question 49

is interstitial growth possible when mineralization takes place for hard tissue to be formed?

Answer 49

no

Question 50

in mineralized tissues, where can hyperplasia, hypertrophy and secretion of extracellular material occur?

Answer 50

only at the surface

Question 51

Why is interstitial growth a prominent aspect of overall skeletal growth?

Answer 51

because a major portion of the skeletal system is originally modeled in cartilage

Question 52

T/F Cartilage is a nearly avascular tissue whose internal cells are supplied by diffusion through the outer layers.

Answer 52

True

Question 53

the chondrocranium develops from what three pairs of cartilaginous precursors?

Answer 53

1-The Ethmoid prechordal cartilages) 2-The Sphenoid hypophyseal cartilages 3-The Occipital parachordal cartilages

Question 54

T/F bone is sometimes formed as a primary tissue

Answer 54

False- Never

Question 55

The bones of the chondrocranium are preformed in cartilage and ossify . this is called?

Answer 55

endochondral ossification

Question 56

what what month does the chondrocranium require a blood supply?

Answer 56

month 4

Question 57

what are the areas in the chondrocranium with an in growth of blood vascular elements called?

Answer 57

they become centers of ossification **this is when/where cartilage is transformed into bone

Question 58

endochondral ossification uses what kind of cartilage to ossify?

Answer 58

Hyaline cartilage **cartilage cells are replaced with bone

Question 59

what 3 bones are formed by endochondral ossification?

Answer 59

1-long bones 2- short bones 3- cranial base (ethmoid, sphenoid, and occipital bone)

Question 60

what is the shaft of a long bone called?

Answer 60

diaphysis

Question 61

what is the cap or end of a long bone called?

Answer 61

epiphysis

Question 62

what is between the diaphysis and epiphysis?

Answer 62

Epiphyseal cartilage **AKA growth plate that is uncalcified

Question 63

when does the Epiphyseal plate disappear?

Answer 63

When the rate of maturating cartilage cells exceeds their proliferation *when proliferation rate is higher, there is growth

Question 64

what part of the long bone continues to change after the epiphyseal plate has disappeared?

Answer 64

the periosteum

Question 65

the embryonic development of flat bones from an embryonic tissue called the mesenchyme is known as what?

Answer 65

Intramembranous ossification

Question 66

what two things does mesenchym differentiate into?

Answer 66

fibrous membrane | cartilage

Question 67

Intramembranous ossification is also responsible or what 2 things?

Answer 67

1-natural healing of bone fractures | 2- bone formation within the periosteum

Question 68

where does intramembranous ossification take place?

Answer 68

in membranes of connective tissue

Question 69

in intramembranous ossification what undergoes ossification?

Answer 69

collagen (NOT cartilage)

Question 70

in intramembranous ossification when osteoid is continually laid around blood vessels trabeculae are formed around them. what does this form?

Answer 70

spongy bone

Question 71

in intramembranous ossification how is compact bone formed?

Answer 71

Trabeculae thickens and continues to lay osteoid

Question 72

what 5 ares use intramembranous ossification?

Answer 72

``` 1-maxilla 2-cranial vault 3- zygomatic 4-temporal 5- most of the mandible ```

Question 73

what type of growth must intramembranous bone use?

Answer 73

appositional at the free surfaces

Question 74

What are the only two ways intramembranous bone can change its shape?

Answer 74

resorption and apposition

Question 75

when does the most cranial growth occur?

Answer 75

before age 5

Question 76

the bones that cover the upper and outer surface of the brain is considered?

Answer 76

the cranial vault

Question 77

, the bony floor under the brain, which also is the dividing line between the cranium and the face is considered?

Answer 77

the cranial base

Question 78

____________ is made up of the nose, maxilla, and associated small bones

Answer 78

the nasomaxillary complex

Question 79

the cranial vault grows by what means?

Answer 79

appositional growth and resorption of the periosteum **intramembranous ossification

Question 80

T/F there is cartilage on the surface of the bones in the cranial vault?

Answer 80

False

Question 81

what are the major sites of bone expansion in the cranial vault?

Answer 81

the sutures

Question 82

are the cranial sutures growth sites or centers?

Answer 82

sites *unossified state, and allow new bone to be formed at the edges of the approximating bone fronts.

Question 83

what are the "soft spots" called on cranium?

Answer 83

fontanelles

Question 84

how does the formation of the cranial base differ from the vault?

Answer 84

the cranial base are formed initially in cartilage and are later transformed by endochondral ossification into bone.

Question 85

what region of the skull is the first to reach adult size?

Answer 85

The cranial base

Question 86

the cranial base has synchondroses that act as growth centers or sites?

Answer 86

centers

Question 87

what makes synchondroses like a double sided growth plate?

Answer 87

the center facilitates hyperplasia and the maturing cartilage extends in both directions **growth on either side is NOT symmetrical

Question 88

the maxilla develops using what type of ossification?

Answer 88

intramembranous **no primary cartiage

Question 89

where is the center for ossification in the maxilla?

Answer 89

the angle between the anterosuperior alveolar nerve and the inferior orbital nerve

Question 90

because of the center of ossification, the maxilla grows in what directions?

Answer 90

Posteriorly, anteriorly, superiorly

Question 91

in the cranial vault surface remodeling is ___________, and in the maxilla it is ____________

Answer 91

minimal, dramatic

Question 92

the growth pattern of the maxilla requires it grows mainly in what 2 directions?

Answer 92

down and forward **maxilla is attached to the anterior end of the cranial base and so lengthening of the cranial base pushes the maxilla forward

Question 93

what important aspect of maxillary growth occurs at around age 7?

Answer 93

cranial base growth stops, and then sutural growth is the only mechanism for bringing the maxilla forward, which is accomplished by growth of the soft tissue.

Question 94

the maxilla grows downward and forward by removing bone where?

Answer 94

on the anterior surface

Question 95

The palatal vault is carried downward and forward along with the rest of the maxilla but at the same time, bone is removed on the ___________ side and added on the ___________ side,

Answer 95

Nasal, oral

Question 96

the two halves of the maxilla are joined by what?

Answer 96

 intermaxillary suture **when growing it contains cartilage

Question 97

how do palate expanders work?

Answer 97

they separate the intermaxillary suture

Question 98

does the mandible replace meckel's cartilage?

Answer 98

NO! , the development of the mandible begins as a condensation of mesenchyme just lateral to Meckel’s cartilage *intramembranous bone formaton

Question 99

The mandibular symphysis is what?

Answer 99

where left and right sides of mandible meet. *as the bone plate lateral to meckel's cartilage extends toward the midline, eventually the halves meet.

Question 100

what produces the development of the alveolar process?

Answer 100

continued bone formation that surrounds the tooth germ

Question 101

what develops by a rapid spread of ossification posteriorly into the mesenchyme turning away from Meckel’s cartilage

Answer 101

the ramus of the mandible

Question 102

Remnants of disintegrated meckel's cartilage end up where?

Answer 102

middle ear

Question 103

is condylar cartilage completely replaced by bone?

Answer 103

No. the upper end purists through adulthood as a growth cartilage and then as articular cartilage

Question 104

when does condylar growth rate increase?

Answer 104

ages 12-14 *growth is done by 20

Question 105

what are the three secondary mandibular cartilages?

Answer 105

1- condylar cartilage-largest 2-coronoid disappears before birth 3-symphyseal cartilage- between ends of Meckle's cart.

Question 106

the symphyseal cartilage replaced early or late in life?

Answer 106

early. within year 1

Question 107

growth of the cranium occurs almost entirely in response to what?

Answer 107

the brain

Question 108

the growth of hte cranial base is primary a result of what?

Answer 108

endochondral growth and bony replacement at the synchondroses

Question 109

T/F Growth of the maxilla and its associated structures occurs from a combination of growth at sutures and through direct remodeling of the surfaces of the bone

Answer 109

True

Question 110

Growth of the mandible occurs by both __________ proliferation at the condyle and by apposition and resorption of bone at the ___________

Answer 110

endochondral, bony surfaces

Question 111

what two areas of the mandible have endochondral ossification?

Answer 111

1-Coronoid cartilage as it is incorporated into the expading intramembranous bone of ramus 2-condylar cartilage is it fuses with ramus