Development and Growth Flashcards
growth vs development
Growth- most relevant to the increased size of anatomy of increase in number of anatomic parts (quantity)
Development- refers more to the greater complexity or specialization of functions (qualitative)
a pattern where early on in life, growth tends to occur faster in parts that are closer to the cranium while parts further away from the cranium experience growth later in life
cephalocaudal growth gradient
Which matures earlier? maxilla or mandible
maxilla (remember cephalocaudal growth gradient)
The human growth curve: distance vs velocity
Distance- person’s height
Velocity- person’s rate of change in height
male vs female peak growth
Male = 14 yo
Female = 12 yo
growth curve that describes the growth of variable body regions in terms of years and percentage of total adult body size
Scammon’s growth curve
- brain and neural tissue grow rapidly after birth and reach near adult size by 6-7 years
- lymphoid tissues grows rapidly to twice its adult size by 10 years and then decreases until adulthood
- maxilla more similar to neural growth curve
- mandible more similar to general growth curve
not a good indicator of maturity due to variability
chronological age
age based on markers of maturation, BEST indicators of growth and maturity (menstruation, secondary sex characteristics)
biologic age
age based on maturity of cervical vertebrae or maturity of hand and wrist bones, better indicator of maturity
skeletal age
age based on teeth that have exfoliated/erupted, generally NOT a good indicator of maturity
dental age
sites vs centers
Sites- parts of the body where the growth is actually occurring
Centers- sites of the body that are able to control its own growth
the main growth centers for craniofacial structures
synchondroses
intramembranous vs endochondral growth
Intramembranous growth
- growth from the outside of bone from fibrous CT (increased DIAMETER of bone)
- controlled more by environmental factors
- found in sutures and cranial vault surface
Endochondral growth
- growth that occurs within cartilage that is eventually replaced by bone, 5 zones
- results in increased bone LENGTH
- controlled more by genetics
- found in the following sites: epiphyseal plates (long bones), synchondrosis of cranial base, condylar cartilage of the mandible
5 zones of endochondral ossification
1) Zone of resting cartilage
2) Zone of proliferation
3) Zone of hypertrophy
4) Zone of calcification
5) Zone of ossification
3 theories of growth
Cartilage theory- epigenetic control of growth where cartilage is the growth center, holds some validity
Suture theory- now known to be mostly false, genetics determine bone growth, sutures act as growth centers (but now we know they are growth sites)
Functional matrix theory- environment (speaking, chewing, function) control growth, causes nasal and oral cavities to grow bigger, primary determinant of growth in maxilla and mandible
