The document summarizes the functional matrix hypothesis, which proposes that craniofacial bone growth is in response to mechanical stimuli from surrounding soft tissues. It revisits the hypothesis by incorporating recent understandings of mechanotransduction, the connected cellular network of bone cells, and the interplay between genetic and epigenetic factors. Specifically, it describes how mechanical loads are sensed by bone cells and transmitted through the cellular network to regulate gene expression and bone formation. It presents the original genomic thesis of bone development being controlled by genes alone, the epigenetic antithesis of multiple developmental processes, and a resolution synthesizing both genetic and epigenetic influences.

1. FUNCTIONAL MATRIX HYPOTHESIS- REVISITED
PRESENTED BY
SUSNA PAUL

2. CONTENTS
• FUNCTIONAL MATRIX THEORY- ORIGINAL
• FUNCTIONAL MATRIX HYPOTHESIS- REVISITED
 ROLE OF MECHANOTRANSDUCTION
 ROLE OF AN OSSEOUS CONNECTED CELLULAR NETWORK
 GENOMIC THESIS
 EPIGENETIC ANTITHESIS & RESOLVING SYNTHESIS
• REFERENCES

3. FUNCTIONAL MATRIX THEORY(1960s)
• The concept of this theory was introduced first by Vander Klaaw
(1948-52).
• Melvin L. Moss developed the functional matrix hypothesis.

4. The craniofacial skeleton develops initially and later grows in direct
response to the extrinsic epigenetic environment..
BONES DO NOT GROW ,THEY ARE GROWN

5. DEFINITION
The origin, form, position, growth and maintenance of all
skeletal tissues and organs are always secondary,
compensatory and necessary responses to chronologically
and morphologically prior events or processes that occur in
specifically related nonskeletal tissues, organs or
functioning spaces (functional matrices).

6. Explanation
The FMH considers the head, not the skull as a composite area of
individual encapsulate areas..
Totality of skeletal structure+ soft tissue+ functioning space
Functional Cranial Component

7. FUNCTIONAL CRANIAL COMPONENT
SKELETAL UNIT FUNCTIONAL MATRIX
MICRO MACRO
PERIOSTEAL CAPSULAR

8. SKELETAL UNIT
MICRO SKELETAL
• Skeletal units may be composed variably of bone, cartilage or
tendinous tissues.
• When a bone consists of a number of skeletal units, we call them
micro skeletal units..

9. MACRO SKELETAL
• When adjoining portions of a number of neighboring bones are
united to function as a single cranial component, we term this as a
macro-skeletal unit.
• eg: endocranial surface of the calvaria

10. THE FUNCTIONAL MATRIX
THE PERIOSTEAL MATRIX
This corresponds to the immediate local environment, which acts
directly..
Egs: muscles, blood vessels, nerves, glands, teeth..

11. • The periosteal matrices stimulation causes direct growth of the
microskeletal units.
• Effect on the size and/or shape of the skeletal unit by osseous deposition
and resorption.
TRANSFORMATION

12. THE CAPSULAR MATRIX
Defined as the organ and spaces that occupy a broader anatomical complex.
Each capsule is an envelope - contain a series of FCC - skeletal unit and the related
functional matrices..
Sandwiched between two covering layers

13. OROFACIAL CAPSULE
In this, the cover consists of skin and mucous membrane.
The orofacial capsule surrounds and protects the orofacial functional
matrix..

14. The volumetric expansion of the orophoryngeal functioning spaces
Increase in the size of the capsule
The whole of the included and enclosed functional components, are
translated to a new position in space.

15. NEUROCRANIAL CAPSULE
• In this, the cover consists of skin and duramater.
• The neuro-cranial capsule surrounds and protects the neurocranial functional
matrix..

16. The expansion of the enclosed capsular matrix volume.
The capsule enlarges
The whole of the included and enclosed functional components, are
carried outward in a totally passive manner.

17. • Thus the capsular matrices acts indirectly on the macroskeletal units and
are carried outward in a passive manner.
• The location in space of the skeletal unit is changed, not by osseous
deposition and resorption.
TRANSLATION

18. FUNCTIONAL CRANIAL
COMPLEX
GROWTH
TRANSLATION
TRANSFORMATION
CAPSULAR
MATRIX
PERIOSTEAL
MATRIX
MACROSKELETON
MICROSKELETON
SKELETAL UNITFUNCTIONAL
MATRIX

19. CONSTRAINTS OF THE FMH
1. Methodologic constraint:
Macroscopic measurements which use the techniques of point mechanics
and arbitrary reference frames.
Roentgenographic cephalometry permitted only method specific
descriptions that cannot be structurally detailed. This constraint was
removed..

20. 2. Hierarchical constraint:
This version’s descriptions did not extend “downward” to processes at
the cellular, subcellular or molecular structural domains or extend
“upwards” to the multicellular process by which bone tissues respond
to lower level signals.

21. 1.Mechanotransduction occurs in single bone cells.
2.Bone cells are computational elements that function multicellularly as a
connected cellular network.
.

22. MECHANO TRANSDUCTION
All vital cells are irritable and respond to alterations in their external
environment.
1. Mechanoreception
2. Mechanotransduction

23. Osseous Mechanotransduction

24. 1.Unlike other mechanosensory cells ,bone cell are not specialized for such
stimuli
2.These cells shows aneural transmission of signals.
3. Bone loading stimulus evoke three adaptational responses.
4. The changes brought about by stimuli are confined to a single bone to which
the signal is transduced.

25. Translates the information content of a periosteal functional matrix
stimulus into a skeletal unit cell signal

26. MECHANOTRANSDUCTION
Ionic / electrical
Mechanical

27. Stretch Activated channel
Activation of plasma membrane stretch activated ion channels
Intra cellular electric events

28. Electromechanical
Involves the osteocytic plasma membrane.
it contains voltage activated ion channels and transmembrane ion
flow..

29. Electrokinetic
Bound and unbound electrical charges, associated with the bone fluids.
Electrical effects in the fluid filled bone are electrokinetic i.e. streaming
potential.

30. MECHANICAL PROCESS
This is an alternate means by which functional matrix may regulate
the lower cell bone cell.

31. The physical continuity of the
transmembrane molecule integrin

32. MECHANORECEPTION
MECHANOTRANSDUCTION
IONIC MECHANICAL
STRETCH ACTIVATED CHANNELS INTEGRIN
ELECTRIC EVENTS
ELECTROMECHANICAL ELECTROKINETIC

33. CONNECTED CELLULAR NETWORK
All bone cells, expect osteoclasts are extensively interconnected by gap junctions.
Present laterally and vertically.
.
Superficial osteoblast Superficial osteoblast
Periosteal and endosteal
osteoblasts
Periosteal and endosteal
osteoblasts
Preosteoblastic cellPreosteoblastic cell
CONNECTED CELLULAR NETWORK

34. • Network theory
Initial layer cells –stimuli (loading)
summation
Intracellular signal (mechanotransduction)
Hidden layer cells (adj. Osteocytes)
Final layer cells (osteoblasts) output

35. The CCNs show oscillation, i.e. reciprocal signaling (feedback) between
layers.
Gap junctions are electrical synapses that permit bi-directional signal
traffic

36. ionic transport through the bone cell plasma membrane
intercellular transmission are computed by the operation of an
osseous connected cellular network
bone responses

38. • explanatory chain extending from the
epigenetic event of skeletal muscle contraction, hierarchically downward (through the
cellular and molecular levels to the bone cell genome and then)
upwards again through histologic levels to the event of gross bone form adaptational
changes.

39. The revised FMH consist of the presentation of, a thesis and an
anti-thesis and of a resolving synthesis.

40. GENOMIC THESIS
• The genomic thesis holds that the genome, from the moment of fertilization, contains
all the information necessary to regulate..

41. • Genomic thesis claims that prenatal cranio facial development is controlled
by two inter related processes:
1. Initial regulatory (Homeobox) gene activity.
2 Activity of the regulatory molecular groups: growth factor families and
steroid/thyroid family.

42. EPIGENETIC ANTITHESIS
The genomic thesis passes directly from molecules to morphogenesis:
directly from DNA molecules to adult morphology, ignoring the roles of the
many epigenetic processes and mechanism.

43. The epigenetic antithesis detailing the processes and mechanisms seeking
to clarify the casual chain between genome & phenotype.
• Process  Series of action or operation that had towards a particular
result.
• Mechanism  Fundamental physical or chemical process(es) involved in,
or responsible for an action, reaction or other nailed phenomenon

44. Epigenetics refers to the entire series of interactions among cells and cell
products, which leads to morphogenesis and differentiation..

45. A RESOLVING SYNTHESIS
• Morphogenesis is regulated (controlled, caused) by the activity of
both genomic and epigenetic processes and mechanisms.

46. REFERENCES
• The functional matrix revisited.1. The role of mechanotransduction. AJODO –1997
; 112 :8-11.
• The functional matrix revisted 2. The role of an osseous connected cellular network
AJODO -1997; 112:221-6
• The functional matrix revisited.3 .The genomic thesis AJODO-1997;112:338-42
• The functional matrix revisited.4 .The epigenetic antithesis AJODO-1997;112:410-7