Functional matrix theory

Functional matrix
hypothesis
-Melvin moss 1960
www.indiandentalacademy.com

Initial formulation
Form and function are intimately related
1867 – Effect of function on bone – femur-
Anatomist Meyer & mathematician Culmann –
Theory of “Trajectory of bone formation”

Initial formulation
• 1870 – Julius Wolff – stated that the
external morphology & internal architecture
of bone is directly proportional to the
functional forces acting upon it
• Modern restatement – WILHELM HIS –
1874 – “physiology of the plastic”

Initial formulation
• Wilhelm Roux & Hans Driesch –
ENTWICKLUNGMECHANIK (developmental mechanism)
• Benninghoff showed that the stress trajectories
obeyed no individual bone limits but rather the
demands of the functional forces
• “Functional cranial component” – Vander
Klauuwwww.indiandentalacademy.com

Stress trajectories

Development of a concept
Dept of anatomy – university of columbia
(1948-51)
“problems of cranial growth in general and
the role of sutures in particular”
Books –
“The development of the vertebral skull – Gaven de beer
“on growth and form” - Thompson

Development of a concept
10 yrs – extensive study
1960 – 1st
paper – YOUNG – American journal of
physical anthropology
1962 – 2nd
major paper - orthodontic community

Point of view
• ‘If neither bone or cartilage were the
determinants for craniofacial growth , it
would appear that the control would have to
be in the adjacent soft tissues’

Classic statement – 1981
• The functional matrix hypothesis claims
that the origin , growth & maintenance of
all skeletal tissues and organs are always
secondary , compensatory and obligatory
responses to temporally and operationally
prior events or processes that occur in
specifically related non-skeletal tissues,
organs or functioning spaces

Basic concept of growth
• Transformation (remodelling)
-change in size and shape
-osseous deposition and resorption
• Translation (displacement)
-change in spatial position
-without osseous deposition and
resorption

Basic concept of growth

Functional cranial component
Skeletal unit Functional matrices
Macroskeletal
Eg-endocranial
surface Of calvaria
Microskeletal
Eg-coronoid,
angular
Periosteal
Eg-teeth and
muscles
Capsular
Eg-orofacial,
neurocranial
Components & concepts

Concepts and components
Head and neck region carry out number of
functions
-Respiration
-Olfaction
-Vision
-Hearing
-Balance
-Chewing
-Digestion
-Swallowing
-Speech
-Neural integration

Components & concepts
• Functional cranial component (FCC) – The
tissues, organs, spaces & skeletal parts necessary
to carry out a given function
• Functional matrix – non-skeletal tissues of a FCC
eg-muscles, glands, nerve ,vessels, teeth
• Skeletal unit – skeletal tissues which protect or
support the functional matrix eg-bone,cartilage &
tendinuous tissue

Skeletal unit
Microskeletal unit– bone composed of several
contiguous skeletal units
eg . Mandible – alveolar
angular
condylar
coronoid
basal

Skeletal unit
• Maxilla- nasal
orbital
pneumatic
basal
alveolar

Skeletal unit
• Macroskeletal unit - adjoining portions of
number of neighbouring bones carrying out
a single function
eg-endocranial surface of calvaria

Functional demands
• Coronoid --------------temporalis
• Angular---------------- masseter & medial
pterygoid
• Alveolar---------------presence of teeth
• Basal-------------------inferior alveolar
neuromuscular triad matrixwww.indiandentalacademy.com

Periosteal matrix
• These are non-skeletal functioning units
adjacent to the skeletal unit.
• Produce secondary – compensatory
transformation
• Best eg:- role of temporalis – coronoid
process

Periosteal matrix
• Removal,denervation –
postinfectively/post-traumatically - decrease
in the size or total disappearance
• Functional hypertrophy/hyperactivity-
increase in size and change in shape

Capsular matrix
• FCC (skeletal + functional matrices)
capsules
• Each capsule is a envelope sandwiching the
FCC in b/w its layers
• Arise , grow, exist , operate & maintained

Capsular matrix

Capsular matrix
4 such cranial capsules exist
Neurocranial capsule
Orofacial capsule
Orbital capsule
Otic capsule

Capsular matrix
• Capsular matrices exist in volumes
• volumetric capsular matrix –
expansion of capsule
• Translation of embedded bones

• Calvarial bones sandwiched b/w the skin & duramater

• Composition
--5 layers of the scalp
outer table
--bone inner table
diploic space
--2 layers of duramater

• Contents
--brain
--leptomeninges volume of NCC
--CSF

• Two important factors
volume of the neural mass
Total neural mass – morphologically significant –
than amount of brain tissue
Expansion of the neurocranial capsule
Primary event – expansion of capsular matrices –
compensatory expansion of capsule – translation of
FCC

• Hydrocephaly
-- passive , non – periosteal translative
growth produced by capsular matrices
--The expansion of the NCC is always
proportional to the increase in neural mass

Orofacial capsule
• Sandwiched b/w skin & mucosa
• Surrounds and protects oronasopharyngeal
functioning spaces
• These 3 spaces (oral,nasal & pharyngeal)are
unitary spaces

Orofacial capsule

Orofacial capsule
• Patency – functional unit
• Related to the general metabolic demands
of the body
• Respiratory functional space volume –
dominant cranial functioning space

Orofacial capsule
WORK OF BOSMA
Primary function – maintenance of patent
airway
Dynamic musculoskeletal postural balance –
“Airway Maintenance Mechanism”
Airway maintained throughout range of
motion of head & neck

Orofacial capsule
• Embryonic development
--originate by process of enclosure
--formation of palate – nasal & oral portions
--Volumetric growth of these spaces is the
primary morphogenetic event in facial skull
growth

Support for the hypothesis
 mandibular growth
--bilateral condylectomy – does not effect growth or spatial
movement of acondylar contiguous structures
Hydrocephaly
Microcephaly
Size of eye and orbit
Teeth and alveolar bonewww.indiandentalacademy.com

CLINICAL ASPECTS
• Etiology of m o due to deficient functioning
eg – mouth breathing,
tongue thrusting,
digit sucking
• Growth modulation is based upon this theory
• Appliances are used to either transmit, eliminate
or guide the natural forces of musculaturewww.indiandentalacademy.com

CLINICAL ASPECTS
• Palate splitting – adjustive and
compensatory reactions of sutural
connective tissue and the immediate
sensitive response of membranous bone to
tensional forces

Shortcomings
• No clear explanation of how functional
needs are transmitted to the tissues around
mouth and nose – Proffit
• Does not suggest unitary mechanism

Functional matrix theory

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