cephalocaudal gradient

1. CEPHALOCAUDAL GRADIENT OF GROWTH
AND
TERMINOLOGIES IN GROWTH AND
DEVELOPMENT
BY RAJALAKSHMI.D

2. CEPHALOCAUDAL GRADIENT OF
GROWTH
 Cephalocaudal means head to toe
 Cephalo – describes things related to head and
brain
 Caudal – toe or tail ( like a tail )
 It means there is an axis of increased
growth extending from head towards the
feet
 Represents the changes in over all body
proportions during normal growth and
development

3. The process of cephalocaudal direction is from head down to the tail this
means that improvement in structure and function come first in the head
region, then in the trunk and last in the leg region
 Physical control comes in the order
HEAD >>>>>> ARMS >>>>>> LEGS

4.  At 3rd month of intra-uterine life head is 50% of the total body length
At birth head is 30% of total body length
At adult head is 12% of total body length

5. CHANGES IN PROPORTIONS OF THE
HEAD AND FACE DURING GROWTH
 Increased gradient of growth is evident even within the head and face
 At birth , the cranium is proportionally larger than the face, but Postnatally
the face grows larger than the cranium.

6. FUNDAMENTAL
TERMINOLOGIES OF
GROWTH AND
DEVELOPMENT

7. GROWTH
 Growth refers to increase in size – Todd 1931
 An increase in size and number – Proffit 1986
 Self multiplication of living substance –
J.S.Huxley
 The normal change in the amount of living
substance – Moyers 1988
 The change in any morphological parameter which
is measurable -Moss

8. DEVELOPMENT
 Development is progress towards maturity –
Todd 1931
 Increase in complexity – Proffit 1986
 A maturational process involving progressive
differentiation at the cellular and tissue level –
Enlow
 All naturally occurring progressive ,
unidirectional , sequential changes in life of an
individual from its existence as a single cell to its
elaboration as a multifunctional unit terminating
in death - Moyers

9. ENDOCHONDRAL OSSIFICATION
 Endo – within , Chondral – cartilage , Ossification – Bone
formation
 The bone formation is preceded by formation of a cartilaginous
model that is subsequently replaced by bone
 All the bones of the body , except for the flat bones of the skull
, mandible and clavicle , are formed through endochondral
ossification. Example : long bones.

10. STAGES OF ENDOCHONDRAL
OSSIFICATION
• Mesenchymal cells are condensed at the sight of bone formation
• It differentiates into chondroblast and lay down hyaline cartilage
• Cartilage is surround by the membrane called the prechondrium which is highly vascular
and contain osteogenic cells
• Intracellular subtances around the cartilage gets calcified due to the influences of
alkaline phosphate enzyme secreted by cartilage cells.
• The nutrition to the cells is cut off leading to their death
• Formation of empty spaces called primary ossification center and the blood vessels
and osteogenic cells of the perchondrium invade the calcified cartilaginous matrix
• Osteogenic cells from the perichondrium becomes osteoblast and lay down osteoid ,
which later gets calcified to form the lamellae of bone
• The same process takes place at the secondary ossification centre at the epiphysis and
the lamellae of bone is formed
• When the ossification of epiphyses gets completed , hyaline cartilage remains only in
the epiphyseal plate and articular cartilage.

12. INTRAMEMBRANOUS OSSIFICATION
 Bone is formed within a fibrous
membrane
 It is formed from the mesenchymal cells
present in the embryonic fibrous
connective tissue
 Bones formed are flat bone of skull ,
mandible and clavicle .

13. STAGES OF INTRAMEMBRANEOUS
OSSIFICATION
• Mesenchymal cells present in the embryonic fibrous connective tissue gets
aggregated at the site of bone formation
• Mesenchymal cells enlarges and acquire a basophilic cytoplasm and forms
osteoblasts
• Osteoblast secrete gelatinous matrix called osteoid around the collagen fibers
• They deposit calcium salts into the osteoid leading to the conversation of
osteoid into bone lamellae
• Now the osteoblast move away from the lamellae and a new layer of osteoid is
secreted which also gets calcified
• Some of the osteoblast gets entrapped within the lamellae , they are called
osteocyte.
• The formed by this method is spongy bone and later by remodelling it forms
the compact bone.

15. GROWTH SITES
 Baume proposed the term growth site
for regions of periosteal or sutural bone
formation and modelling resorption
adaptive to environmental influences
 a site of growth is merely a location at
which growth occurs
All the growth centers are sites but the
reverse is not true
Sites in mandible : condyle and ramus

16. GROWTH CENTER
Site of endochondral ossification
with tissue separating force,
contributing to the increase of
skeletal mass
 i.e location at which independent
(genetically controlled) growth
occurs

17. REMODELLING
 A process involving deposition and resorption
occurring on opposite ends is called remodelling
 Four types
• Biochemical remodelling
• Growth remodelling
• Haversian remodelling
• Pathological remodelling

18.  The changes that bone
deposition and resorption
cause are
• change in size
• change in shape
• change in proportion
• change in relationship of
the bone with adjacent
structures.

19. GROWTH MOVEMENTS
Cortical drift
 A combination of bone deposition and
resorption resulting in a growth movement
towards the depositing surface is called
cortical drift
 If the deposition and resorption are equal
on both the sides then shape remains
constant.
 If there is more deposition on one side and
less bone resorption on the other side then
thickness of the bone increases.

20. DISPLACEMENTS
It is the movement of the whole bone as a unit
 Two types
PRIMARY DISPLACEMENT
• The bone gets displaced as the result of its own growth
• Example :growth of maxilla at the tuberosity region resulting in pushing the maxilla
against the cranial base which results in the displacement of the maxilla in a forward

21. Secondary displacement
Bone gets displaced as a result of growth and enlargement of an
adjacent bone.
 Example : The growth of the cranial base causes the forward and downward
displacement of the maxilla