Matríz funcional

The primary role of functional

matrices in facial growth
Melvin
1. Moss,
New York, N. P.

D.D.S.,

Ph.D.,

and

Letty

Salentijn,

D.D.S.

D

uring the past decade the method of functional
cranial analysis
has been developed in our laboratory. The basic postulates and the experimental
and clinical supporting data have been published extensively elsewhere.4-“Y Theorthodontic specialty recently became aware of this analytical technique, with
particular interest being expressed in the derivat,i\-e concept of the Jurrctionul
matrix. In view of the current reappraisal of the theories of cranial bone growth
by many workers (Scott3” and EnlowZA), it is appropriate
to indicate the
contribution
which the analytical
method makes toward the resolution of
thisproblem. The present review first defines the two basic types of functional
matrices (periosteal and capsular) and then demonstrat.es their differing and
yet complementary
roles as the primary morphogenetic
agencies in skeletal
tissue growth.
Functional

cranial

analysis

A brief review of basic postulates is necessary. Operationally,
the head is a
region within which certain functionsoccur. Every function
is completely
carried out by a functional cranial conaponed. Each such component, in turn,
is composed of two parts: (1) a functional matrix which actually carries out the
function and (2) a skeletal unit whose biomechanical role it is to protect, and/or
support its specific functional
matrix. Abundant
data demonstrate
that all
growth changes in the size, shape, andspatial position and, indeed, the very
maintenance in being, of all skeletal units are always secondary to temporally
primary changes in their specific functional matrices. To clarify this seemingly
sweeping statement, it is necessary to define t,he terms skeletal unit and functional matrix
in greater detail.
From
the
Department

Division
of
of Anatomy,

This study
was aided,Institute
of Neurological

566

Oral Biology,
College
of

School
Physicians

of

Dental
and
and Surgeons,

in part,
by a research
grant
Diseases,
National
Institutes

(NB-00965)
of Health.

Oral
Surgery,
and
Columbia
University.
from

the

National

the

Punctiomd

V olume
55
Nunz her 6

matrices in facial growth

567

Skeletal units may be composedvariably of bone, cartilage, or tendinous
tissues. They are not the equivalents of the “bones” of formal, classic osteology.
When such a “bone” consists of a number of skeletal units, we call them microskeletal units; that is, both the maxilla and the mandible arc formed of a number
of such contiguous microskeletal units. When adjoining portions of a number
of neighboring “bones” are united tofunction as a single cranial component,
we term this a macroskeletal unit; the cndocranial surface of the calvaria is an
example.
In the mandible we distinguish easily a coronoid microskclctal unit related
to the functional demands of the temporalis muscle; an angular microskelet,al
unit related to the activity of both the masseter and medial pterygoid muscles;
an alveolar unit related to thepresence and position of teeth; and a basal microskeletal unit related to the inferior alveolar neurovascular triad matrix Thcrc
are other mandibular microskeletal units which have been detailed elsewhcre?~ I4
To a variable extent, contiguous microskeletal units are independent
of each
other. This implies that changes in the size, shape, or position of the coronoid
process as a result ofprimary changes in temporalis muscle are relatively
independent of such changes in other mandibular microskeletal units.
The term functionaZ ma,t,rix is by no means equivalent to what is commonly
understood as “soft tissues,” this is, muscles, glands, nerves, vessels, fat, etc.,
although all of these are obviously included within the concept. Teeth are also
a functional matrix, as the...