Craniofacial Growth I Flashcards
What are the 4 characteristics of growth?
- Quantitative
- Proportional
- Sprouts (or jumps)
- Decelerated
What is the definition of growth?
- Hypertrophy/hyperplasia
It is a change in size/weight resulting from an increase in number or size of cells
What is growth measured in?
Centimeters or Kilograms
Growth leads to? (2)
- Development (differentiation)
- Maturation (stabilization)
Define development/differentiation? (2)
- tissue differentiation to achieve somatic and functional characteristics
- changes in shape and structure from embryo to adult, from lower to higher stage
Define maturation (stabilizations)?
Stabilization of the
adult condition achieved thanks to the growth and development.
What are the growth influence factors? (4)
- cephalocaudal trend
- different growth rhythms in each type of tissue
- foreseeable nature
- individual variability
Growth factors: What is cephalocaudal trend? (3)
- Proximal growth before distal
- Medial growth before lateral
- Dorsal growth before ventral
Growth factors: What are the Different growth rhythms in each kind of tissue? (2)
• The reproductive organs are the last to develop.
• The brain and head are the ones that suffer
development the soonest
Growth factors: what is foreseeable nature?
There are events and changes that happen in a foreseeable order that cannot be altered
Growth factors: What is individual variability? (2)
•There exists a reasonable variation among the
normality. That is why growth charts have been
created.
•This growth charts define the child position in
relation to the group and enables to follow the
child´s growth through time.
What are the different types of growth? (2)
- Intramembranous ossification
- endochondral ossification
Intramembranous ossification and pressure?
Areas WITHOUT pressure
Endochondral ossification and pressire?
Areas WITH pressure
What is intramembranous ossification?
It forms directly from sheet-like layers of fibrous
connective tissue
What are the steps of intramembranous ossification? (3)
Step 1: Mesenchymal cells differentiate to osteoblasts
that secrete organic matrix bone.
Step 2: Bone forms between blood vessels randomly
forming a trabeculae.
Step 3: Trabeculae thickens at the periphery to form
plates of compact bone
All the bones in the skull and clavicle are formed in this way…?
Intramembranous ossification
What is endochondral ossification?
- Mesenchymal tissue transforms to cartilage in the same shape of bone.
- Cartilage is broken down, reorganized and mineralized to form bone
What are the steps of endochondral ossification? (3)
Step 1: Chondroblasts form hyaline cartilage. This is surrounded by perichondrium,
which becomes bone forming periosteum.
Step 2: Cartilage calcifies in the center of the diaphysis. Chondrocytes die due to
calcification. The ends of the bone still have healthy chondrocytes so the bone
model enlarges.
Step 3: Primary ossification bud expands. Blood vessels, osteoblasts and osteoclasts
reach the epiphysis.
The condyle and the nasal septum are formed this way…?
Endochondral ossification
What is involved with differential growth? (2)
- remodelling
- displacement
What is bone remodelling?
bone deposition and resorption
Bone remodelling responds to ____?
Functional demands
What changes does bone remodelling produce? (4)
- size
- shape
- proportion
- relationship of bone with adjacent structure
When does bone remodeling begin?
14th week
What is cortical drift?
A combination of remodelling that results in a growth movement towards the depositiing surface
What relationship between bone remodelling results in bone with the same thickness?
When deposition = resorption
What relationship between bone remodelling results in an increase of bone thickness?
When deposition is more than resorption
When there is a cortical drift towards the surface of deposit it creates…
Growth movement or displacement
What are reversal lines?
Lines that separate an alternation of areas of resorption and deposition in the same surface
Perisoteal surfaces are…
50% resorption and 50% deposition
Differential bone growth produces…
Huge changes on the internal bone surface provoking relocation of different parts
What is a growth site?
Parts of bone that have a more important role in growth
Bone remodelling areas characteristics? (2)
- They may be of deposition or reabsorption.
* The pattern of these areas stay constant
Bone remodelling areas: factors that may have an influence? (3)
- Size of area
- Rhythm and quantity of deposit / resorption
- Regulation of the time of growth activity
Bone remodelling functions? (5)
• Enlarge the bone.
• Relocate the different bone parts.
• Modify the bone so new functions may be performed.
• Change the bone relationship with adjacent bones and
soft tissues.
• Create continuous local structural adjustments.
What is the “V” principle? (3)
- V shaped pattern of remodellng growth
- Growth occurs towards the wide end of the V
Where can you find the V pattern of growth? (4)
- Palate
- Neck of condyle
- Coronoid apophysis
- Zygomatic arches
Growth occurs towards the wide end of the “V” as a result of: (3)
- Differential deposition
- Selective resorption of bone
- Simultaneous displacement towards the wide end
Displacement: During bone growth there are…
Independent movement
provoked by a physical force that separates the articulations
Moss´s functional matrix theory says …
the growth of the soft tissues provokes a “passive displacement” that
will induce bone growth
What is primary displacement?
- Due to the own enlargement of the bone
- Physical displacement combined with bone enlargement
Primary displacement: the displacement is equal to…?
The amount of bone growth
What is secondary displacement? Example?
- Displacement due to the action of other bones growth and the soft tissues
- ex. growth of the cranial base causes the forward and downward
displacement of the maxilla
Secondary displacement: the sense of displacement and sense are ___
opposite
