UCSF Growth and Development Flashcards
Describe difference between growth control Sites vs Centers
Site: Location at which growth occurs
Center: Location at which independent (genetically controlled) growth occurs
**All centers are sites, but not all sites are centers
T/F, Sutures and Synchondroses are growth centers
False, the sutural theory was disproven.
- Sutures transplanted to another site do not continue to grow
- Sutures respond to outside influences
Are sutures growth sites or growth centers or both
They are growth sites only
T/F, Condylar cartilage does not have innate growth potential and nasal septum cartilage has some innate growth potential.
True
Growth at the condyle is similar to sutures of maxilla, growth is reactive
What is the functional matrix theory of growth described by Moss?
Functional needs lead to enlargement of structures and cavities.
Name the two methods of bone formation
Intramembranous ossification
Endochondral ossification
Intramembranous ossification mainly occurs in what bones?
flat bones of the skull
bone is formed from mesenchyme tissue
Endochondral ossification occurs in what bones?
Long bones such as limbs
Bone is formed from cartilage
Primary ossification centers are responsible for the formation of what?
Diaphyses of long bones, short bones, and certain parts of irregular bones
Secondary ossification centers are responsible for the formation of what?
Epiphyses of long bones and extremities of irregular and flat bones
What separates the diaphyses and epiphyses?
Growing zone of cartilage called the eiphyseal plate.
These are fused together when a child reaches skeletal maturity and cartilage is replaced by bone
Where are osteoclasts derived from?
Bone Marrow (hematopoetic)
Where are Fibroblasts and Osteoblasts derived from?
Mesenchymal cells
By what method of bone formation are the bones in the cranial vault formed?
Intramembranous
By what method of bone formation is the mandible formed?
Both Intramembranous and Endochondral
Condyle is endochondral
By what method of bone formation is the maxilla formed?
Intramembranous
By what method of bone formation is the Cranial base formed?
Endochondral
Growth at synchondrosis, formed initially in cartilage and then endochondral ossificataion
Which develops from secondary cartilage?
a. midpalatal suture
b. vomer
c. condylar head
d. cornu of hyoid bone
Condylar head
Which bones of the skull are formed by intramembranous ossification?
Frontal and Parietal bones
Temporal is formed partially by endochondral and partially by intramembranous
What has sutural growth, endochondral growth, and remodeling?
Neurocranium and midface
No mandible, no sutural?
Describe Meckel’s cartilage in relation to ossification of the mandible
Lateral to the mandible intramembranous ossification
How does the maxilla grow?
By intramembranous ossification entirely.
Apposition at sutures that connect maxilla to the cranium and cranial base
By surface remodeling
Define undermining resorption
Occurs when capillary pressure is exceeded and results in hyalinization (pressure necrosis, sterile necrosis, avascular area of PDL)
Four types of Bone
Woven
Lamellar
Composite
Bundle
Define Woven bone
Newly formed bone (embryonic skeleton; orthodontics, etc.)
**It is first bone formed in response to orthodontic movement
Eventually it is compacted into either composite or remodeled to lamellar
Describe Lamellar bone
Strong and highly orgnaized
Describe Composite bone
a mixture of lamellar bone and woven bone
Describe Bundle bone
Functional adaptation of lamellar bone for attachment of tendons and ligaments
How to cartilage and bone growth differ?
Cartilage can grow by both appositional and interstitial growth
Bone can only grow through appositional growth
What anatomical structures in the head can grow through interstitial growth?
Mandibular condyle
nasal septum
sphenooccipital synchondrosis
What is interstitial growth?
Chondrocytes divide within the cartilage
T/F, Cartilage tissue is avascular
True
T/F, at birth, the right and left side of the maxilla are not fused
True
What is Enamelin?
Major organic component of mature enamel
What components are present in a matrix of developing enamel?
Amelogenin
Enamelin
Tuft protein
When nasal septum is deviated, where is the normal location?
Inferior 1/3
The external human face develops between what weeks during embryonic development?
4-6 weeks
What processes come together to form the external face?
- Frontonasal process (medial nasal and lateral nasal processes)
- Tissues of first (or mandibular) pharyngeal arch
The primary palate is formed by what processes?
Medial Nasal and Maxillary processes
The secondary palate is formed by what processes?
fusion between palatal processes growing from the oral surfaces of the maxillary processes
What occurs at day 17 in embryonic development?
Germ layer formation and initial organization of structures
*Fetal Alcohol syndrome - midline structures affected
What occurs during day 18-23 in embryonic development?
Neural tube formation
What occurs during day 19-28 in embryonic development
Origin and migration of the cell populations
*Treacher collins, Hemifacial microsomia
What occurs during day 28-28 (4-6 weeks) in embryonic development
Primary palate formation
*Cleft lip/palate
What occurs during day 42-55 (6-8 weeks) in embryonic development
Secondary palate formation
Final differentiation of tissues occurs at what date?
Day 50 - birth
This is when synostosis syndromes occur caused by early fusion of sutures.
A typical branchial arch contains what 4 things?
- Aortic arch
- Cartilaginous rod
- Muscular component
- Nerve
At what day mark do pharyngeal arches form?
22 days
What nerve is associated with the first branchial arch?
Trigeminal
What nerve is associated with the second branchial arch?
Facial
What nerve is associated with the third branchial arch?
Glossopharyngeal
According to scammon’s growth curves, neural tissues are completed by what age?
Age 7
At what age is a child’s head 90% it’s adult size?
At age 6
From ages 6-12, the boyd’s lymph tissue is what percentage of it’s normal adult mass?
200%
Peak velocity height occurs at what ages for boys and girls?
Girls: 12-13
Boys: 14-16
Late maturing girls PVH can be identified by asking about what?
Menarche
PVH occurs 6-11 months before menarche
T/F, a short upper lip and lip incompentency in mixed dentition is not normal and should be evaluated for early treatent
False, it is normal, lip growth trails behind growth of jaws so it seems short but will lengthen during adolescence
At what point in life does the lip thickness reach its maximum
During adolescence. It decreases in adulthood
Tongue reaches full size at what age?
8 years
T/F, nose never stops growing in males?
True
The thyroid develops from what feature?
Foramen cecum
What is velopharyngeal insufficiency?
Inability of velum to elevate during speech leading to hypernasal speech and snoring
Flat bones of the cranial vault form through what type of ossification?
Intramembranous
At what age does the spheno-occipital synchondrosis close?
12-15y
At what age does the spheno-ethmoidal synchondrosis close?
3-5y
At what age is the inter-sphenoidal syncondrosis fused?
At birth
Name the synchondroses of the cranial base?
Spheno-occipital
Spheno-ethmoidal
Inter-sphenoidal
What is a synchondroses?
a small un-ossified band of cartilage found between bones undergoing endochondral ossification
**Sutures related with intramembranous ossification and do not have cartilage
Growth of synchondroses lengthens the cranial base until what age?
7 y
What is the chondrocranium?
it is the combination of ethmoid, sphenoid and basi-occipital bones
How does growth of the maxilla occur?
Apposition of bone at sutures
Surface remodeling
Describe the areas of surface remodeling in the maxilla
- Anterior surface is resorptive (except ANS)
- Posterior surface is depository
- Roof of mouth is depository
- Nasal side is resorptive
What are the areas of resorption in maxillary growth
superior and anterior
What are the areas of deposition of maxillary growth?
Posterior and inferior
Where does the maxilla not have bone deposition?
Superior and Anterior
What is the most stable surface of the midface?
Zygomatic process between orbital rim and key ridge
How does growth of the mandible occur?
Endochondral ossification and surface remodeling. Condensation of mesenchyme lateral to Meckel’s cartilage is formed by intramembranous bone formation.
- Condyle - cartilage replacement (EO)
- all other mandibular growth is by direct surface apposition and resorption
Meckel’s cartilage gives rise to what?
Incus
Malleus
Sphenomandibular ligament
Describe the areas of resorption and apposition in the mandible
- Anterior surface of ramus is resorptive
- Posterior surface of ramus is depository
- Creates a upward and backward direction of growth causing the mandible to move downward and forward
Name the stable mandibular structures
- Anterior contour of chin
- Inner cortical structures at inferior border of symphysis
- trabecular structures in symphysis
- trabecular structures related md canal
- Lower contour of molar germ from time mineralization of crown is visible until root not formed.
Name the 7 signs of growth rotation
- inclination of condylar head
- curvature of the mandibular canal
- Shape of mandibular lower border. Thick cortical layer in area of symphysis and concavity at angle present for vertical growers
- Symphysis inclination
- Interincisal angle, will be more retroclined in vertical growers
- interpremolar and intermolar angles
- anterior lower face height is more elongated in vertical growers
What structure is smallest at birth compared to its size in adulthood?
Mandible
Which growth ends first, mandibular or maxillary?
Maxillary
Condylar growth occurs by what type of growth?
Endochondral/proliferation of cartilage
Growth in body of the mandible occurs by what type of growth?
Initially intramembranous but appositional is major form
Late mandibular growth in a patient with tight anterior occlusion may cause what things?
- Distal displacement of mandible
- Flaring of maxillary incisors
- Crowding of mandibular incisors
Rotational growth of the mandible is shown by what indicators?
- Bending of mandibular canal
2. Condylar neck angle
Mandibular growth rate in females is greater in what direction?
Vertical is greater than AP
How does the body of the mandible lengthen
by remodeling of anterior ramus
- resorption at anterior border of ramus allos for increase in mandibular corpus length
Name the mandibular growth sites
- condylar process
- posterior border of ramus
- dentoalveolar process
After age 6, greatest increase in size of the mandible occurs where?
Distal to the first molars
Sesamoid ossification indicates what?
2-3 years of growth spurt remaining after first appearance.
About 60-70% of growth remaining
- The sesamoid ossifies 1 year prior to the pubertal maximum growth spurt
what does SMI = 7 indicate?
MP5 capping
75% of growth completed
With hand-wrist x-rays, what is an important indicator of skeletal maturity?
Fusion of epiphysis and diaphysis of distal phalanx of 3rd finger
- This indicates that growth spurt is over
The peak in mandibular growth will occur within one year of observing this CVMS stage
CVMS III
So CVMS II/III represents the ideal stage to begin functional jaw orthopedics
When does Menarche occur in relation to Peak Height Velocity?
1.2 to 1.3 years after PHV
