Physio of stomatognathic system

The Physiology of the
Stomatognathic System
1.Functional Osteology
2.Myology
3.Functions of the Stomato-
gnathic System
4.TMJ
functions of the stomato
-gnathic system…
Respiration
Deglutition
Speech
Olfaction
Mastication
www.indiandentalacademy.com

INTRODUCTION
Mostly in the past orthodontic evaluations
were done in based on how the upper jaw
meet the lower jaw in occlusion which is
static analysis,but nowadays its mandatory
to appreciate the concept of dynamic
occlusion since function can influence the
overall pattern and relationship of the
parts,the very foundations of the
stomatognathic system.

FUNCTIONAL
OSTEOLOGY
Although bone is the hardest tissue
in the body,it is one of the most
responsive to change when there is an
alteration in the environmental
balance .as an orthodontist can establish
a perfect occlusion of teeth,but unless he
takes into consideration the effects of
the use of these teeth,unless he makes
allowances for the manifold
environmental functional influences,the
delicately responsive bony structures are
apt to change,and the tooth positions

There are various bones that make up
the skull,we will study these from the
orthodontic point of view as the cranial
component and the mandibular
component.Both these components are joined
by the Temporomandibular joint which is the
most often used joint.functionally all the various
bones act as a single unit.

Functional Osteology
Relationship of form and function

The functional matrix hypothesis
This theory describes the
relationship of form and
function.
It claims that the
origin,form,position,growth
and maintenance of all
skeletal tissues and organs
are always
secondary,compensatory
and necessary responses to
chronologically and
morphologicaly prior events
or processes that occur in
specifically related non-
skeletal tissues,organs or
functioning spaces.

Functional matrix hypothesis

Trajectorial theory of bone formation-
Meyer & Culmann
The alignment of the bony
trabeculae followed definite
engineering Principles.when lines
were drawn following discernible
columns of oriented bony
elements,these lines showed a
structure similar to the
trajectories seen in a crane.
Trajectories were seen to be
crossing at right angles to each
other.Enabling the bones to resist
the Functional stresses it is
subjected to.

Beninghoff’s trajectories of Force
Categorized the trajectories of forces for the maxilla and
the Mandible.trajectories are nothing but lines of
orientation of bony trabeculae.
These are the pathways of Maximal
pressure and tension And bone
trabeculae is Thicker in these regions
where Stresses are greater.
Maxillary trajectories are…
Vertical:
a) Canine
b) Zygomatic buttress
c) Pterygo-maxillary
Horizontal:
Hard palate, orbital floors

Trajectories of the mandible

trajectories for mandible
The trabecular columns radiate
from beneath the alveolar process and
join together in a common stress pillar
that terminates in the mandibular
condyle.The mandibular canal and
nerve are protected at the same time
by this concentration of trabaculae(this
demonstrates the unloaded nerve
concept)

Wolff’s Law and internal
architecture of Bone.
The size and the shape of bone is a direct representation of
the function it performs or carries out.according to this law
the trabecular alignment was due primarily to functional
forces.Bone elements once formed rearrange themselves in
the direction of the functional pressure and increase or
decrease their mass to Reflect their… “functional stress”.this
law is also known as the law of orthogonality.

The internal Architecture of bone.
Changes in the functional forces can produce a
remarkable change in the bony architecture..

Postural abnormalities and bony
changes
Kyphosis –or curvature of spine,in which
some vertebrae are stressed unevenly
Osteoporosis- lack of function leads to
reduced density of bone tissue ,Osteosclerosis-
increased function produces a greater density
of bone in a particular area.

Changes associated with hyper
functioning and hypo functioning
. Changes in size and shape.
. Alveolar bone density and
associated radiological
changes.
. Due to postural changes and
Increased stresses

Sexual and ethnic variations

Myology
In defining normal muscle
Functions…
Swallowing patterns
Neutral zone
Buccinator mechanism

Muscles of facial expression
The muscles of the face are….
Epicranium,orbicularis oris,zygomaticus
major,levator labii
superioris,buccinator,mentalis,platysma
,risorius,orbicularis occuli,corrugator
supercilii,levator palpebrae superioris.

Importance of the Buccinator
mechanism
Force exerted by the lip musculature
anteriorly and buccinator,and muscles of
the cheek posteriorly is counteracted by the
force exerted by the tongue.Thus balanced
force is transmitted to the teeth and
supporting bone

Buccinator mechanism
The major factor in environmental balance is the
muscle musculature.muscles are a potent
force,whether they are in active function or at
rest.As already seen even a resting muscle is
performing a function,that is maintaining posture and
a relationship of contiguous parts.The teeth and
supporting structures are constantly under the
influence of the contiguous musculature.The integrity
of the dental arches and the relations of the teeth to
each other within each arch and with opposing
members are the result of the morphogenic pattern,as
modified by the stabilizing and active functional
forces of the muscles.www.indiandentalacademy.com

An arch form is defined by
its encompassing soft-tissue
Drape.
What are the possible
Effects due to imbalances !
Passive muscle function / Neutral zone

TONGUE
The physiology of tongue is important for the orthodontist,when
swallowing,tongue thrust,open bite are taken into consideration .In infancy
the extrinsic muscles attach the tongue to various osseous structures and are
largely responsible for gross movements,mostly in the horizontal plane(suckle-
swallow).the genio glossus most involved in the plunger like suckle-
swallow.there are four intrinsic muscles,they are-superior longitudinal,inferior
longitudinal,vertical and transverse.
the tongue has amazingly versatile functional possibilities by the virtue of
the fact that it is anchored at only one end.this very freedom permits the
tongue to deform the dental arches when function is abnormal.when the
tongue activity is abnormal,irrespective of its cause which may be a
compensatory response to abnormal morphogenetic pattern or retained
infantile or visceral swallow,the balance between the outside and inside force
is disturbed which leads to development of malocclusion like maxillary
anterior protrusion,open bite and narrowing of maxillary arch.

tongue --contd
compensatory mentalis activity may follow
this and exert a strong retracting force on
mandibular incisors.malocclusion reprsents
natures attempt to establish balance
between all morphogenetic ,functional and
environmental components.A malocclusion is
dynamic balance at that particular
time.tongue plays a very important role in the
functions of stomatognathic system like
mastication,deglutition,respiration and
speech.most functions are a net result of
the activity or two or more muscles.

functional movements
The mandible is the only movable bone
in the body .The muscles bring about
the movements of mandible.the
muscles that bring about the functional
movements of mandible are-
temporalis,lateral pterygoid,
masseter,supra hyoid,infra hyoid.

Normal swallowing patterns -
Infantile swallow
. Gum pads (absence of teeth)
. Anterior Mouth seal
. Mandibular stabilization
Features of infantile swallow
Lip seal thro’ circumoral activity
and associated tongue posturing
in-between the gum pads.
Mandible stabilized against the tongue
Nerve involved is the …..????

Normal swallowing patterns
Adult swallow
… Teeth together swallow.
… Mandibular stabilization.
… Anterior lip seal.
Nerve involved….????

The Physiology of the
Stomatognathic System
Enumerating functions…
Respiration
Deglutition
Speech
Olfaction
Mastication
Maintenance of Head posture

Moyers characteristics of
swallowing
Characteristics of infantile swallow
Jaws are apart with the tongue between the gum pads
The mandible is stabilized by contraction of the muscles of the 7th
Cranial nerve and the interposed tongue
The swallow is guided and to a great extent controlled by sensory
Interchange between the lips and the tongue.
Characteristics of mature swallow
Teeth are together
Mandible is stabilized by the contraction of the mandibular elevators
5 th cranial nerve
The tongue tip is held against the palate above and behind the incisors
Minimal contractions of the lips during the mature swallowwww.indiandentalacademy.com

Comparison…?

Phases of deglutition
Fletcher’s division of the deglutition cycle
Preparatory phase
Oral phase
Pharyngeal phase
Esophageal phase
… Once a minute during meals
… Nine times during eating
… 2400 in a twenty four our period !!!www.indiandentalacademy.com

Tongue positions during
swallowing

Classification
of tongue
thrust
James S Braner and Holt
Deforming and Non-
Deforming
Also…
Simple tongue thrust
Complex tongue thrust

Speech
Labiodental - “f” and “v”
Bi-labial - “p, b--w, m”
Linguo-dental - “th”
Linguo-alveolar
“t”, “d”, “s”, “z” and
“n”
Linguo-palatal
“Ch”, “j” , “sh”.
Linguo-velar
…ng”
Linguo-velar-pharyngeal
“k” “g”

T M J - Essential Anatomy

Positions of the Mandible
To understand the variations from the normal the basic sagittal
Plane positions of the mandible with respect to the maxilla and
The cranium.
The Basic mandibular positions are…
1. Postural resting position-”Physiological rest position’
2. Centric relation
3. Initial contact
4. Terminal Hinge position-most retruded position
5. Most protruded position
6. Habitual rest position
7. Habitual occlusal positionwww.indiandentalacademy.com

Factors affecting Physiological
rest position
Factors are…
1. Body and posture
2. Sleep
3. Psychic factors influencing the muscle tonus
4. Age
5. Proprioception from the dentition and the muscles
6. Occlusal changes
7. Pain
8. Muscle disease and muscle spasm
9. Tmj disease

Conclusion

Physio of stomatognathic system

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