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Physiology of the
Stomatognathic System
INDIAN DENTAL ACADEMY
Leader in continuing Dental
Education
www.indiandentalacademy.com
CONTENTS
 MANDIBULAR MOVEMENTS
 ENVELOPE OF MOTION
 OCCLUSAL CONTACTS DURING MOVEMENTS
 CENTRIC RELATION & CENTRIC OCCLUSION
 FUNCTIONAL OCCLUSION
 NEUROMUSCULAR SYSTEM
 PHYSIOLOGY OF PAIN
 MUSCLES
 BIOMECHANICS OF TMJ
 MASTICATION
 DEGLUTITION
 SPEECH
 APPLIED PHYSIOLOGY
 BIBLIOGRAPHY www.indiandentalacademy.com
Introduction
It is mandatory to appreciate the
concept of dynamic appreciation since
function can influence the overall pattern
and relationship of the parts, the very
foundations of the stomatognathic system.
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STOMATOGNATHIC SYSTEM
The structures involved in speech & in
receiving, chewing & swallowing food
including the oral cavity, teeth, jaws,
pharynx & related structures.
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Gnathology
Gnathology - Term given by: McCOLLUM (mid
1920s’)
Science that deals with biology of masticatory
system
• Science dedicated to the study of oral cavity as a
functional unit, in direct relationship to its
morphology, histology, physiology & therapy
including its vital relation with the rest of the body.
Gnathostatic model - A cast of the teeth; trimmed
so that the occlusal plane is in its normal position
in the oral cavity when the cast is set on a plane
surface. Such casts are used in the gnathostatic
technique of orthodontic diagnosiswww.indiandentalacademy.com
MANDIBULAR MOVEMENTS
TYPES OF MOVEMENT :
Two types of movements:-
 Rotational
 Translational
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Rotational movement
 The process of turning around an axis:
movement of a body about its axis.(Dorland’s
illustrated medical dictionary)
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Horizontal Axis of Rotation:-
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Frontal axis of rotation
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Sagittal axis of rotation
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TRANSLATION MOVEMENT
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Single-Plane Border Movements
When the mandible moves through the outer range of
motion, reproducible describable limits result, which are
called border movement.
These occur in three different planes:-
Sagittal plane
Horizontal plane
Frontal plane
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SAGITTAL PLANE BORDER
AND- FUNCTIONAL MOVEMENTS
Mandibular motion in the sagittal plane have four distinct
movement:-
1. Posterior opening border
2. Anterior opening border
3. Superior contact border
4. Functional
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Posterior Opening Border Movements:-
20- 25 mm
40-60 mmwww.indiandentalacademy.com
ANTERIOR OPENING BORDER MOVEMENTS
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SUPERIOR CONTACT BORDER MOVEMENT

The superior contact border movement is determined by
the characteristics of the occluding surfaces of the
teeth:-
1. The amount of variation between CR and
maximum intercuspation
2. The steepness of the cuspal inclines of the
posterior teeth
3. The amount of vertical and horizontal overlap of
the anterior teeth
4.The lingual morphology of the maxillary anterior
teeth
5. The general interarch relationships of the teeth.
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Centric occlusion vs. centric relation
 Centric relation: it is the maxillo-mandibular relationship in which
the condyles articulate with the thinnest avascular portion of their
respective disks with the complex in the anterior superior position
against the shapes of the articular eminences, the position is
independent of the tooth contact. (GPT-5)
 Also called ligamentous positon or terminal hinge position
 If Centric occlusion coincides with the centric relation they appear to
be the same.
 Centric relation is bone to bone relation while centric occlusion is
tooth to tooth relation.
 Centric occlusion does not coincide with the centric relation in most
of the people with natural teeth.
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 Centric occlusion: it is
the occlusion of opposing
teeth when mandible is in
centric relation.Also
known as maximal
intercuspal position (ICP)
or habitual occlusion.
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 Centric relation
 Centric occlusion
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Functional occlusion
It is defined as an arrangement of teeth
which will provide the highest efficiency
during all excursive movements of
mandible which are necessary during
function
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The slide from CR to intercuspal position is present in approx 90% of
Population & the average distance is 1.25+_ 1 mm according to Sears VH
in 1925
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SUPERIOR CONTACT BORDER MOVEMENT
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FUNCTIONAL MOVEMENTS
 Most functional activities begin at and below the
intercuspal position.
When the mandible is 2 to 4 mm below the intercuspal
position it is at rest.
 This is called the clinical rest position. (Young & Meyer)
 At this position the muscles have not their least
amount of activity.
 The muscles are at their lowest level of activity when the
mandible is 8 mm inferior and 3 mm anterior to the
intercuspal position according to Stallard & Stuart in
1963
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FUNCTIONAL MOVEMENTS
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Postural effects on functional movements
 Final closing stroke as related to
head position.
 A
the head upright- the teeth are
elevated directly into maximum
intercuspation from the postural
position
B
With the head raised 45
degrees- the postural position of
the mandible becomes more
posterior. When the teeth
occlude, tooth contacts occur
posterior to the intercuspal
position.
C
With the head angled downward
30 degrees- the postural
position of the mandible
becomes more anterior, When
the teeth occlude, tooth contacts
occur anterior to maximum
intercuspation.
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HORIZONTAL PLANE BORDER
AND FUNCTIONAL MOVEMENTS
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When mandibular
movements are viewed in
the horizontal plane, a
rhomboid-shaped pattern
can be seen
This movement has 4
components:-
1. Left lateral border
2. Continued left lateral
border with protrusion
3. Right lateral border
4. Continued right lateral
border with protrusion
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Left Lateral Border
Movement:
 Continued Left
Lateral Border
Movements with
Protrusion:
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 The opposing or the balancing condyle moves down, forward and
inward and makes an angle with the median plane when projected
perpendicularly on the horizontal plane
 The lateral shift of the mandible called bennett movement is
measured by the distance of the condyle on working side.
 According to Posselt this movement is 1.5 to 3 mm
 This angle is called the bennett angle
 The lateral movement may have a retrusive or protrusive
component or move straight laterally
 The movement may end at any point in 60 degree triangle
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Right Lateral
Border
Movements:-
Continued Right
Lateral Border
Movements with
Protrusion:
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Functional movements:
During chewing the range of jaw movements begins some
distance from the maximum Intercuspal position but as the food
is broken down into smaller particle sizes the jaw action comes
closer to the ICP .
Centric relation
Intercuspal position
Area used just before swallowing
Area used in early stage of mastication
End to end position of anterior teeth
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FRONTAL (VERTICAL) BORDER
AND FUNCTIONAL MOVEMENTS
 In the frontal plane, a shield-
shaped pattern is seen in four
distinct movement components
:-
1. Left lateral superior
border
2. Left lateral opening
border
3. Right lateral superior
border
4. Right lateral opening
border
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Left Lateral
Superior Border
Movements:-
Left Lateral
Opening Border
Movements:-
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Right Lateral
Superior Border
Movements:-
Right Lateral
Opening Border
Movements:-
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Functional Movements:-
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Envelope of motion in 3D
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Occlusal contacts during mandibular
movements
 Eccentric movement:
 protrusive
 laterotrusive
 retrusive
 Protrusive mandibular movement:-
 Occurs when the mandible moves forward from the ICP.
 In normal occlusion protrusive contacts occur on the
anterior teeth between the incisal edges and the labial
edges of the mandibular incisors and against the lingual
fossa areas and incisal edges of the maxillary incisors.
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 Contacts occur between the
distal inclines of the
maxillary teeth and mesial
inclines of the opposing
fossae & marginal ridges
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 In anterior teeth canines contact and therefore have laterotrusive
contacts, occurs between the labial surfaces and incisal edges of
mandibular canines and lingual fossa and incisal edges of maxillary
canines.
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 Retrusive
mandibular
movement:-
 Occurs when the
mandible moves
posteriorly from the ICP.
 Mandibular buccal cusps
move distally across the
opposing maxillary cusps
 Contacts occur between
the distal inclines of the
mandibular teeth and the
mesial inclines of the
maxillary teeth.
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Neuromuscular system
Neuromuscular: neuron +musculus
It’s a Greek word which pertains to the
nerves and muscles
A highly refined neurological control system
which regulates and coordinates the activity of
the entire muscular system
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ANATOMY AND FUNCTIONS OF
NEUROMUSCULAR SYSTEM

Neurological structures:-
Nerve cell bodies in
spinal cord are found in
gray substance of CNS
& outside are grouped
together as ganglia
Neuron
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Depending on their location & function neurons are
designated by different terms:
1)Afferent neurons
 2) Efferent neuron
 3) Interneuron
Nervous impulses are transmitted from one
neuron to another only at a synaptic junction or
synapse.
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Graphic depiction of the peripheral nerve input
into the spinal cord
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SENSORY RECEPTORS :-
Located in all body tissue and provides
information to the CNS by way of the afferent
neurons.
Some receptors are specific for discomfort and
pain these are called nociceptors.
Receptors that provide information regarding the
position and movement of the mandible and
associated oral structures are called
proprioceptors.
Receptors that carry information regarding the
status of the internal organs are referred to as
interoceptors. www.indiandentalacademy.com
 The masticatory system uses 4 major types of
sensory receptors:-
1. Muscle spindle
2. Golgi tendon organs
3. Pacinian corpuscles
4. Nociceptors
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Muscle spindle
I a, or A alpha-
primary endings or
Annulospiral endings
II, or A beta-
secondary endings or
flower spray endings
Length monitoring
system
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2) Golgi tendon organs:
• They protect the muscle from excessive
or damaging tension
• Tension on the tendons stimulates the
receptors in the golgi tendon organ
therefore the contraction of the muscle
also stimulates the organ.
• Primarily monitor tension
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3)Pacinian corpuscles: -
• Large oval organs made of concentric
lamellae of connective tissue
• These are the structures that serves for the
perception of the movement and firm
pressure.
• These corpuscles are found in the tendons,
joint, priosteum, tendinous insertion, fascia,
and subcutaneous tissue.
• Pressure applied to such tissues deforms
the organ and stimulates the nerve fiber.www.indiandentalacademy.com
4)Nociceptor:
• These are sensory receptors that are stimulated
by injury, and transmit injury information to CNS.
• Nociceptors function to monitor the condition,
position, and movement of the tissues in the
masticatory system.
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Reflex action:-
It is a response resulting from a stimulus that
passes as an impulse along the afferent neuron
to a posterior nerve root or its cranial equivalent,
where it is then transmitted to an efferent neuron
leading back to the skeletal muscle
 A reflex action may be monosynaptic or
polysynaptic.
 monosynaptic reflex
 polysynaptic reflexwww.indiandentalacademy.com
Two general reflex actions are important in
the masticatory system:-
(1) myotatic reflex
(2) nociceptive reflex.
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1)Myotatic reflex or stretch reflex
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2) Nociceptive reflex or flexor reflex
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Clasp knife reflex or autogenic inhibition
Functional significance- protect the overload by preventing damaging
contraction
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Mechanism of Orofacial Pain
Pain is the physical sensation associated with
injury or disease
Nociception – noxious stimulus originating from
sensory receptor.
Pain – unpleasant sensation perceived in the
cortex, usually as a result of incoming
nociceptive input
Suffering- how the human reacts to the
perception of pain
Pain behaviour- individuals audible & visible
actions that communicate suffering to others
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Types of pain
 Differentiate between site & source
1. Primary pain
2. Heterotopic pain
a. Central pain eg brain tumors
b. Projected pain eg. Entrapment of cervical nerve
c. Referred pain eg myocardial infarction
 3 clinical rules
 Passing from one branch to another in a laminated
manner okeson 1995
 Sometimes outside the nerve – moves cephalad not
caudal
 In head neck region never crosses the midline
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2) MUSCLES
To propel human skeleton there are 639
muscles,6 billion muscle fibers.
Each fiber has 1000 fibrils…so at 1 time
or another there are 6000 billion fibrils at
work.
Two important physical properties-
Elasticity – F = AE
D L
Contraction
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MUSCLE FUNCTION:-
The entire muscle has three potential functions:-
Isotonic contraction (e.g)-The masseter
contracts to elevate the mandible forcing the teeth
through a bolus of food
Isometric contraction- When a number of motor
unit contract opposing a given force the function of
muscle is to stabilize the jaw. This contraction
without shortening is called Isometric contraction
(e.g occurs in the masseter when an object is held
between the teeth (pen).
Controlled relaxation-When stimulation of the
motor unit is discontinued, the fibers of the motor
unit relax & return to their normal length. (e.g).In
the masseter when the mouth opens to accept the
new bolus of food during masticationwww.indiandentalacademy.com
Eccentric contraction – at the precise
moment of motor vehicle accident, the
cervical muscles contract to support the
head & resist movement. If the impact is
great sudden changes in inertia of head
causes it to move while the muscles contract
trying to support it. The result is sudden
lengthening of muscles while they are
contracting
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Fig. 5. Lateral cephalometric tracings of mandible in open-mouth (1)
and postural resting (2) positions, occlusion (3), and overclosure (4).
Positional influence of mandible on strength of muscle contraction is
shown by the fact that between 2 and 3 the greatest force is created.
Magnitude falls off rapidly between 3 and 4.
Resting length
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Muscle strength
Maximum force of muscle when all its
fibers are stimulated to ‘fire’
Summation of contractions= 4 x ‘single
contraction’
Muscle strength is directly proportional to
cross sectional area i.e 3 to 10 kg per
square centimeter of cross section
(Ganong in 1971)
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Principles of muscle physiology
Best way to visualize innervaion of muscle is by use of
an electromyogram.
1. All or none law- Sherrington in 1947 pointed out that
individual fibers have no variable contraction status, but
are either relaxed or going into maximum contraction by
virtue of adequate stimulus.
Strength of muscle will depend on- frequency of stimuli &
no. of fibers involved
Not present during muscle fatigue (Merton in 1956)
2. Muscle tonus
3. Resting length
4. Myotatic reflex
5. Reciprocal innervation & inhibition- Sherrington in 1947www.indiandentalacademy.com
Reciprocal Innervation:
For the mandible to be elevated by the temporal, medial
pterygoid, or masseter muscles must contract while the
suprahyoid muscles must relax and lengthen.
The neurologic controlling mechanism for the antagonistic
groups is known as reciprocal innervation.
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• MOTOR UNIT:
 When the neuron are activated the motor end
plate is stimulated to release small amounts of
acetylcholine.
 This initiates depolarization of the muscle fibres
and causes the muscle fibers to shorten or
contract.
 A single motor neuron may innervate only few
muscle fibers or more (e.g):inferior lateral
pterygoid & masseter
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Antagonistic mechanism of muscles:-
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Biomechanics of TMJ
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A small change in the TMJ may cause Pathology
PVD & OVD disharmony- Effect on temporalis & masseter
Overclosure with excessive retrusive activity of posterior
temporalis fibers along with masseter
Pterygoid muscle under constant tension causes repeated
stretch reflex & spasms(Graber TM 1969)
This holds the disc anteriorly while condyles push it posteriorly
& upwards. So a click while condyle rides over the posterior
periphery of disc followed by impingement of postauricular
connective tissue
This condition may be mistaken for arthritis.
Shore feels that clicking or popping in TMJ is because of
jumping forward of condyle a fraction of second ahead of disc
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Major functions of masticatory system
1. Mastication
2. Swallowing
3. speech
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Mastication
Fletcher summarizes his work on masticatory stroke in the adult, using the
six phases outlined by Murphy.
a) The preparatory phase
In which food ingested and positioned by the tongue with in the oral cavity
and the mandible is moved towards chewing side.
b) Food contact
It is characterized by a momentary hesitation in movement. This Fletcher
interpreted to be a pause triggered by sensory receptors concerning the
apparent viscosity of the food and probable trans-articulator pressures
incident to chewing.
c) The crushing phase
If starts with high velocity then slows as the food is crushed and packed.
d) Tooth contact
Accomplished by a slight change in direction but not delay. According to
Murphy all reflex adjustments of the musculature for tooth contact are
completed in the crushing phase before actual contact is made.This was
supported by Moller in 1966
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e) The grinding phase
 Which coincides with transgression of the
mandibular molars across there maxillary
counterparts and is therefore highly constant from
cycle to cycle. Messerman in 1963 termed this
phase the terminal functional orbit.
 Ahelgren noted that during this phase the
bilateral musculature discharge becomes unequal
and asynchronous indicating that the person is
chewing unilaterally.
f) Centric occlusion
 When movement of the teeth comes to a definite
and distinct stop at a single terminal point from which
the preparatory phase of next stroke begins.
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Mastication
Chewing stroke-
Frontal view
16-18 mm
5-6mm
3mm vertical
3-4 mm lateral
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Although mastication occurs bilaterally, about
78% of observed subjects have a preferred side
where the majority of chewing occurs (pond & Barghi)
This normally is the side with the greatest
number of tooth contacts during lateral glide
Chewing on one side leads to unequal loading of
TMJ
Average length of time for tooth contact during
mastication is 194 msec (Suit,Gibbs & Benz)
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Tooth contacts during mastication
 Two types-
1. Gliding
2. Single contact
 Mean percentage of gliding contacts
during chewing- 60% during grinding
phase & 50 % during opening phase
(Suit,Gibbs & Benz)
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When the posterior teeth contact in undesirable
lateral movement, the malocclusion produces an
irregular & less repeatable chewing stroke (Suit,Gibbs & Benz)
Marked difference between chewing strokes of
normal persons & TMJ patients (Mongini, Tempia- Valenta
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Andersen 1956- relation of chewing stroke with different
food consistency
According to Gibbs harder the food the more lateral the
closure strokes become
The harder the food the more chewing strokes needed
(Horio & kawamura )
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Forces of mastication
Males
Female’s max biting load range- 79- 99 pounds( 35.8-
44.9 kg)
Male’s- 118-142 pounds(53.6- 64.4 kg) by Berkhaus in
1941
The greatest maximum biting force reported is 975
pounds(443 kg) by Gibbs et al in 1985
Molars- 91-198npounds(41.3- 89.8 kg)
Central incisors- 13.2- 23.1 kg) by Howell & Manly in
1948
 With age up adolescence (Garner, Kotwal, Worner, Andersen 1944,
1973)
Can be increased with practice & exercise
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In a study done by Gibbs et al in 1981 reported
grinding phase of closure stroke averaged 58.7
pounds on posterior teeth- about 36.2 %
subjects maximum biting force
Bakke & mischler in 1991- tooth pain reduces
amount of force used during chewing
According to a study done by Ramjford in 1961
when teeth contact evenly & simultaneously in
the retruded position, the muscles of mastication
have decreased activities & more harmonious
during mastication
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Role of tongue in mastication
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Deglutition
It is a series of coordinated muscle
contractions that moves a bolus of food
from the oral cavity through the
esophagus to the stomach
It consists of voluntary, involuntary &
reflex muscular activities
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Stabilization of mandible is an important part of
swallowing
Somatic swallow- teeth for mandibular stability
The average tooth contact during swallowing lasts
about 683 msec 3x longer than mastication (Suit,Gibbs &
Benz 1975)
Force applied = 66.5 pounds- 9.8 pounds more than
mastication (Suit,Gibbs & Benz 1975)
Infantile or visceral swallow- mandible is braced by
placing tongue forward & between dental arches or
gum pads
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Phases of deglutition by Fletcher
Preparatory phase
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Oral stage
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Pharyngeal stage & Velopharyngeal
mechanism
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• ACTION OF THE VELOPHARYNGEAL VALVE
• ETIOLOGY
o absence of structure (e.g., cleft palate),
o disproportion of structure (e.g.. short palate, deep
nasopharynx, short functional palate).
o neurologic defects (e.g., muscle or central nervous
system)
VELOPHARYNGEAL INCOMPETENCE
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Esophageal stage
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Fig. 14. Bar graph illustrating comparative muscle pressures during the
normal swallowing act. Only lateral and medial pterygoid, middle
temporalis, and anterior and posterior masseter fibers show moderate
activity. The remainder demonstrate slight activity.
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Fig. 15. Bar graph illustrating comparative muscle pressures
associated with abnormal swallowing. Note heavy mentalis and lip
activity, dominance of posterior temporalis and masseter fibers, and
increased hyoid muscle action. (See Fig. 14.)
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Frequency of swallowing
Flanagan et al in 1963 demonstrated
swallowing cycle occurs 590 times during
24 hr period :
146 cycles during eating
394 cycles between meals while awake
50 cycles during sleep
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Speech:
Speech is an expression of thoughts by production
of articulate sound, bearing a definite meaning.
It is very sophisticated, autonomous, & unconscious
activity
Its production involves neural, muscular,
mechanical, aerodynamic, acoustic, & auditory
factors
It is one of the highest functions of brain
It is brought about by the coordinated activity of
different parts of brain, particularly the motor &
sensory www.indiandentalacademy.com
It occurs when a volume of air is forced from the
lungs by diaphragm through the larynx & the oral
cavity
Vocal cords create sounds with desired pitch &
then precise form assumed by mouth
determines the resonance & exact articulation of
sound
Expiration & inspiration
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Mechanism of speech:
Speech depends upon the coordinated activities
of central & peripheral speech apparatus
The central speech apparatus consists of higher
centres- the cortical & subcortical centres
The peripheral speech apparatus includes
larynx, pharynx, mouth, nasal cavities, tongue, &
lips
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Speech production; structural & functional
demands:
Controlling airstream that is initiated in the
lungs & passes through the larynx & vocal
cords produces all speech sounds
Adjustments in the airflow contribute to
variations of pitch & intensity of the voice
The structural controls for the speech sounds
are the various articulations or valves made in
pharynx & the oral & the nasal cavities
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Each sound is affected by the length, diameter
& elasticity of the vocal tract & by the locations
of constrictors along its length
Because nearly all speech sounds are emitted
from the mouth, the nasopharynx is closed off
from the oropharynx during speech
Closure is performed by an upward lift of the
soft palate
Intimacy of the pharyngeal wall contact, as well
as magnitude of movement by the soft palate,
varies with the nature & sequence of the
speech sounds
www.indiandentalacademy.com
As the outgoing air passes through the mouth,
tongue, lips, & mandibular oscillations modify
it.
The tongue has a critical impact on speech
production & needs optimal mobility to lift,
protrude, flatten, forms a groove & contact
adjacent tissues freely.
Jaw and tooth relationship enable the tongue
to articulate against the maxillary teeth or
alveolus.
www.indiandentalacademy.com
The 1st
speech sounds are the bilabial sounds
‘m, p & b’
Somewhat later the tongue tip consonants like
‘t’ & ‘d’ appear
The sibilant ‘s’ and ‘z’ sounds which require
that the tongue tip be placed close to but not
against the palate, come later still & the last
speech sound ‘r’ which requires precise
positioning of the posterior tongue, often is not
acquired until age 4-5
Tongue & palate for ‘d’
Articulations of sound
www.indiandentalacademy.com
www.indiandentalacademy.com
Speech difficulties related to
malocclusion:
s,z (sibilants) - Ant. Open bite, large gap
between incisors
t,d (Linguoalveolar stops) - Irregular
incisors
f,v (Labiodental fricatives) - Skeletal
class III
th,sh,ch (linguodental fricatives) - Anterior
open bite
www.indiandentalacademy.com
Lisping
This speech defect involves change of sound of letters and
wards.
Etiology
Main cause is continuity of infantile mode of speech.
If the tongue is moved forward without mandible and lies on
top of lower incisors lisping may result.
Certain malocclusions like openbite, maxillary protrusion,
mandibular retrusion and malaligned tooth also cause lisping.
Stammering
In stammering the child fails to produce any sound for
sometime. These create emotional tension and difficulty in
social adjustment.
Etiology
Hereditary
Due to emotional tension
Lack of balance among two hemispheres of the brain.
Auditory amnesia www.indiandentalacademy.com
APPLIED PHYSIOLOGY
www.indiandentalacademy.com
www.indiandentalacademy.com
Buccinator mechanism
www.indiandentalacademy.com
BUCCINATOR MECHANISMBUCCINATOR MECHANISM
Winders has shown that during mastication & deglutition tongue exerts
2-3 times as much force on dentition as lips & cheeks at 1 time
Sphincter like
Purse string effect
www.indiandentalacademy.com
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
Absence of buccinator mechanism
www.indiandentalacademy.com
www.indiandentalacademy.com
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
Leads to development of malocclusion like
maxillary anterior protrusion, open bite and
narrowing of maxillary arch.
www.indiandentalacademy.com
Mature tongue posture:
During mandibular posture, the dorsum touches
the palate slightly and the tongue tip normally is
at rest in the lingual fossa or at the crevices of
the mandibular incisors.
www.indiandentalacademy.com
Abnormal tongue posture:
 Retracted tongue posture
 Protracted tongue posture( Retained infantile
tongue posture)
www.indiandentalacademy.com
Fig. 1. Normal
structural relationship.
Note proximity of
tongue and palate;
gentle, un-strained lip
contact; normal
overbite and overjet.
Fig. 20. Sagittal section illustrating Class
II, Division 1 relationship.Note lowered
tongue posture, narrowed buccal dental
segments in maxillary arch, and lower lip
cushioning to lingual aspect of maxillary
incisors during rest and active function. Lip
and tongue team up to accentuate
deformity.www.indiandentalacademy.com
Fig. 26. Tongue and lip adaptation to Class III malocclusion. Relatively
functionless lower lip in marked contrast to excessive activity
associated with Class II, Division 1 malocclusion. Lower tongue
position is similar, but with no anterior thrust on deglutition. Greater
upper lip activity is in evidence in the attempt to "close off" during
swallowing.
www.indiandentalacademy.com
FRANKEL PHILOSOPHY
Frankel believes that active muscle & tissue mass
has a potential restraining effect on the outward
development of the dental arches
Abnormal perioral musculature exerts a deforming
action that prevents full accomplishment of the
optimal growth & development pattern
Frankel visualizes his vestibular constructions as
“ought to be” matrix that allows the muscles to
exercise & adapt.
www.indiandentalacademy.com
CPG & MUSCLE ENGRAM
Within the brainstem is a pool of neurons
that controls rhythmic muscle activities.
This pool of neurons is collectively known
as central pattern generator (CPG)
For precise timing of activity
With the feedback information that allows
CPG to determine the most appropriate &
efficient chewing stroke
It becomes a learned pattern & is
repeated. This learned pattern is muscle
engram
www.indiandentalacademy.com
SUMMARY AND CONCLUSION
Before the orthodontist appreciates abnormal
functions of the oro-facial muscles he must have
a knowledge of their normal development and
maturation.
A malocclusion is dynamic balance at that
particular time.
In Orthodontics whenever a patient comes his
teeth will be in the most stable position with the
contiguous structures
As form is related to function, the function
should be corrected for achieving the best form
& stability in the long runwww.indiandentalacademy.com
BIBLIOGRAPHY
Jeffrey P.Okeson management of temporomandibular
disorders and occlusion,5th
edition, 29-44,93-107.
Major M. Ash, Sigurd Ramfjord; Occlusion; 4th
edition;164-168.
 Aurthr C Gyton, John E Hall; text book of medical
physiology; 9th
edition; W.B. Saunders; pg 803-805,
1048-1050
Robert E Moyers; Handbook of orthodontics; 4th
edition;year book medical publishers; pg 84-85, 173-
174, 203-205, 209-212),
GraberVolume The "three M's": Muscles, Malformation
and Malocclusion,1963 Jun (418 - 450):
www.indiandentalacademy.com
 T.M.Graber; Thomas Rakosi; Alexander Petrovic;
Dentofacial orthopedic with functional appliance;2nd
edition,
mosby; pg 143-145, 126-130.
 T.M.Graber; Bedrich Neumann; Removable orthodontic
appliances; 2nd
edition; W.B.saunders company; pg 145-
154, 167-169.
 Chien-Lun Peng, DDS, PhD,a Paul-Georg Jost-Brinkmann,
Priv Doz, Dr med dent,b Noriaki Yoshida, DDS,PhD,c Hsin-
Hua Chou, DDS, PhD,d and Che-Ton Lin, DDS,
PhDe,Comparison of tongue functions between mature and
tongue-thrust swallowing—an ultrasound investigation,
American Journal of Orthodontics and Dentofacial
Orthopedics,Volume 125, Number 5
 William R Profitt; contemporary orthodontics; 4th
edition;
mosby Elsevier publication; pg 84-86.
 K Sembulingam, Prema Sembulingam; essentials of
medical physiology; 4th
edition; jaypee brothers; pg 244-
246, 847-848.
 George A Zarb, Charles L Bolender; prosthodontic
treatment for edentulous patients;12th
edition; Mosby
Elsevier publication; pg 379-385.www.indiandentalacademy.com
Thank you
www.indiandentalacademy.com

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Physiology of stomatognathic system ppt

  • 1. Physiology of the Stomatognathic System INDIAN DENTAL ACADEMY Leader in continuing Dental Education www.indiandentalacademy.com
  • 2. CONTENTS  MANDIBULAR MOVEMENTS  ENVELOPE OF MOTION  OCCLUSAL CONTACTS DURING MOVEMENTS  CENTRIC RELATION & CENTRIC OCCLUSION  FUNCTIONAL OCCLUSION  NEUROMUSCULAR SYSTEM  PHYSIOLOGY OF PAIN  MUSCLES  BIOMECHANICS OF TMJ  MASTICATION  DEGLUTITION  SPEECH  APPLIED PHYSIOLOGY  BIBLIOGRAPHY www.indiandentalacademy.com
  • 3. Introduction It is mandatory to appreciate the concept of dynamic appreciation since function can influence the overall pattern and relationship of the parts, the very foundations of the stomatognathic system. www.indiandentalacademy.com
  • 4. STOMATOGNATHIC SYSTEM The structures involved in speech & in receiving, chewing & swallowing food including the oral cavity, teeth, jaws, pharynx & related structures. www.indiandentalacademy.com
  • 5. Gnathology Gnathology - Term given by: McCOLLUM (mid 1920s’) Science that deals with biology of masticatory system • Science dedicated to the study of oral cavity as a functional unit, in direct relationship to its morphology, histology, physiology & therapy including its vital relation with the rest of the body. Gnathostatic model - A cast of the teeth; trimmed so that the occlusal plane is in its normal position in the oral cavity when the cast is set on a plane surface. Such casts are used in the gnathostatic technique of orthodontic diagnosiswww.indiandentalacademy.com
  • 6. MANDIBULAR MOVEMENTS TYPES OF MOVEMENT : Two types of movements:-  Rotational  Translational www.indiandentalacademy.com
  • 7. Rotational movement  The process of turning around an axis: movement of a body about its axis.(Dorland’s illustrated medical dictionary) www.indiandentalacademy.com
  • 8. Horizontal Axis of Rotation:- www.indiandentalacademy.com
  • 9. Frontal axis of rotation www.indiandentalacademy.com
  • 10. Sagittal axis of rotation www.indiandentalacademy.com
  • 12. Single-Plane Border Movements When the mandible moves through the outer range of motion, reproducible describable limits result, which are called border movement. These occur in three different planes:- Sagittal plane Horizontal plane Frontal plane www.indiandentalacademy.com
  • 13. SAGITTAL PLANE BORDER AND- FUNCTIONAL MOVEMENTS Mandibular motion in the sagittal plane have four distinct movement:- 1. Posterior opening border 2. Anterior opening border 3. Superior contact border 4. Functional www.indiandentalacademy.com
  • 14. Posterior Opening Border Movements:- 20- 25 mm 40-60 mmwww.indiandentalacademy.com
  • 15. ANTERIOR OPENING BORDER MOVEMENTS www.indiandentalacademy.com
  • 16. SUPERIOR CONTACT BORDER MOVEMENT  The superior contact border movement is determined by the characteristics of the occluding surfaces of the teeth:- 1. The amount of variation between CR and maximum intercuspation 2. The steepness of the cuspal inclines of the posterior teeth 3. The amount of vertical and horizontal overlap of the anterior teeth 4.The lingual morphology of the maxillary anterior teeth 5. The general interarch relationships of the teeth. www.indiandentalacademy.com
  • 17. Centric occlusion vs. centric relation  Centric relation: it is the maxillo-mandibular relationship in which the condyles articulate with the thinnest avascular portion of their respective disks with the complex in the anterior superior position against the shapes of the articular eminences, the position is independent of the tooth contact. (GPT-5)  Also called ligamentous positon or terminal hinge position  If Centric occlusion coincides with the centric relation they appear to be the same.  Centric relation is bone to bone relation while centric occlusion is tooth to tooth relation.  Centric occlusion does not coincide with the centric relation in most of the people with natural teeth. www.indiandentalacademy.com
  • 18.  Centric occlusion: it is the occlusion of opposing teeth when mandible is in centric relation.Also known as maximal intercuspal position (ICP) or habitual occlusion. www.indiandentalacademy.com
  • 19.  Centric relation  Centric occlusion www.indiandentalacademy.com
  • 20. Functional occlusion It is defined as an arrangement of teeth which will provide the highest efficiency during all excursive movements of mandible which are necessary during function www.indiandentalacademy.com
  • 21. The slide from CR to intercuspal position is present in approx 90% of Population & the average distance is 1.25+_ 1 mm according to Sears VH in 1925 www.indiandentalacademy.com
  • 22. SUPERIOR CONTACT BORDER MOVEMENT www.indiandentalacademy.com
  • 25. FUNCTIONAL MOVEMENTS  Most functional activities begin at and below the intercuspal position. When the mandible is 2 to 4 mm below the intercuspal position it is at rest.  This is called the clinical rest position. (Young & Meyer)  At this position the muscles have not their least amount of activity.  The muscles are at their lowest level of activity when the mandible is 8 mm inferior and 3 mm anterior to the intercuspal position according to Stallard & Stuart in 1963 www.indiandentalacademy.com
  • 28. Postural effects on functional movements  Final closing stroke as related to head position.  A the head upright- the teeth are elevated directly into maximum intercuspation from the postural position B With the head raised 45 degrees- the postural position of the mandible becomes more posterior. When the teeth occlude, tooth contacts occur posterior to the intercuspal position. C With the head angled downward 30 degrees- the postural position of the mandible becomes more anterior, When the teeth occlude, tooth contacts occur anterior to maximum intercuspation. www.indiandentalacademy.com
  • 29. HORIZONTAL PLANE BORDER AND FUNCTIONAL MOVEMENTS www.indiandentalacademy.com
  • 30. When mandibular movements are viewed in the horizontal plane, a rhomboid-shaped pattern can be seen This movement has 4 components:- 1. Left lateral border 2. Continued left lateral border with protrusion 3. Right lateral border 4. Continued right lateral border with protrusion www.indiandentalacademy.com
  • 31. Left Lateral Border Movement:  Continued Left Lateral Border Movements with Protrusion: www.indiandentalacademy.com
  • 32.  The opposing or the balancing condyle moves down, forward and inward and makes an angle with the median plane when projected perpendicularly on the horizontal plane  The lateral shift of the mandible called bennett movement is measured by the distance of the condyle on working side.  According to Posselt this movement is 1.5 to 3 mm  This angle is called the bennett angle  The lateral movement may have a retrusive or protrusive component or move straight laterally  The movement may end at any point in 60 degree triangle www.indiandentalacademy.com
  • 33. Right Lateral Border Movements:- Continued Right Lateral Border Movements with Protrusion: www.indiandentalacademy.com
  • 35. Functional movements: During chewing the range of jaw movements begins some distance from the maximum Intercuspal position but as the food is broken down into smaller particle sizes the jaw action comes closer to the ICP . Centric relation Intercuspal position Area used just before swallowing Area used in early stage of mastication End to end position of anterior teeth www.indiandentalacademy.com
  • 36. FRONTAL (VERTICAL) BORDER AND FUNCTIONAL MOVEMENTS  In the frontal plane, a shield- shaped pattern is seen in four distinct movement components :- 1. Left lateral superior border 2. Left lateral opening border 3. Right lateral superior border 4. Right lateral opening border www.indiandentalacademy.com
  • 37. Left Lateral Superior Border Movements:- Left Lateral Opening Border Movements:- www.indiandentalacademy.com
  • 38. Right Lateral Superior Border Movements:- Right Lateral Opening Border Movements:- www.indiandentalacademy.com
  • 40. Envelope of motion in 3D www.indiandentalacademy.com
  • 41. Occlusal contacts during mandibular movements  Eccentric movement:  protrusive  laterotrusive  retrusive  Protrusive mandibular movement:-  Occurs when the mandible moves forward from the ICP.  In normal occlusion protrusive contacts occur on the anterior teeth between the incisal edges and the labial edges of the mandibular incisors and against the lingual fossa areas and incisal edges of the maxillary incisors. www.indiandentalacademy.com
  • 42.  Contacts occur between the distal inclines of the maxillary teeth and mesial inclines of the opposing fossae & marginal ridges www.indiandentalacademy.com
  • 43.  In anterior teeth canines contact and therefore have laterotrusive contacts, occurs between the labial surfaces and incisal edges of mandibular canines and lingual fossa and incisal edges of maxillary canines. www.indiandentalacademy.com
  • 44.  Retrusive mandibular movement:-  Occurs when the mandible moves posteriorly from the ICP.  Mandibular buccal cusps move distally across the opposing maxillary cusps  Contacts occur between the distal inclines of the mandibular teeth and the mesial inclines of the maxillary teeth. www.indiandentalacademy.com
  • 45. Neuromuscular system Neuromuscular: neuron +musculus It’s a Greek word which pertains to the nerves and muscles A highly refined neurological control system which regulates and coordinates the activity of the entire muscular system www.indiandentalacademy.com
  • 46. ANATOMY AND FUNCTIONS OF NEUROMUSCULAR SYSTEM  Neurological structures:- Nerve cell bodies in spinal cord are found in gray substance of CNS & outside are grouped together as ganglia Neuron www.indiandentalacademy.com
  • 47. Depending on their location & function neurons are designated by different terms: 1)Afferent neurons  2) Efferent neuron  3) Interneuron Nervous impulses are transmitted from one neuron to another only at a synaptic junction or synapse. www.indiandentalacademy.com
  • 48. Graphic depiction of the peripheral nerve input into the spinal cord www.indiandentalacademy.com
  • 49. SENSORY RECEPTORS :- Located in all body tissue and provides information to the CNS by way of the afferent neurons. Some receptors are specific for discomfort and pain these are called nociceptors. Receptors that provide information regarding the position and movement of the mandible and associated oral structures are called proprioceptors. Receptors that carry information regarding the status of the internal organs are referred to as interoceptors. www.indiandentalacademy.com
  • 50.  The masticatory system uses 4 major types of sensory receptors:- 1. Muscle spindle 2. Golgi tendon organs 3. Pacinian corpuscles 4. Nociceptors www.indiandentalacademy.com
  • 51. Muscle spindle I a, or A alpha- primary endings or Annulospiral endings II, or A beta- secondary endings or flower spray endings Length monitoring system www.indiandentalacademy.com
  • 52. 2) Golgi tendon organs: • They protect the muscle from excessive or damaging tension • Tension on the tendons stimulates the receptors in the golgi tendon organ therefore the contraction of the muscle also stimulates the organ. • Primarily monitor tension www.indiandentalacademy.com
  • 53. 3)Pacinian corpuscles: - • Large oval organs made of concentric lamellae of connective tissue • These are the structures that serves for the perception of the movement and firm pressure. • These corpuscles are found in the tendons, joint, priosteum, tendinous insertion, fascia, and subcutaneous tissue. • Pressure applied to such tissues deforms the organ and stimulates the nerve fiber.www.indiandentalacademy.com
  • 54. 4)Nociceptor: • These are sensory receptors that are stimulated by injury, and transmit injury information to CNS. • Nociceptors function to monitor the condition, position, and movement of the tissues in the masticatory system. www.indiandentalacademy.com
  • 55. Reflex action:- It is a response resulting from a stimulus that passes as an impulse along the afferent neuron to a posterior nerve root or its cranial equivalent, where it is then transmitted to an efferent neuron leading back to the skeletal muscle  A reflex action may be monosynaptic or polysynaptic.  monosynaptic reflex  polysynaptic reflexwww.indiandentalacademy.com
  • 56. Two general reflex actions are important in the masticatory system:- (1) myotatic reflex (2) nociceptive reflex. www.indiandentalacademy.com
  • 57. 1)Myotatic reflex or stretch reflex www.indiandentalacademy.com
  • 58. 2) Nociceptive reflex or flexor reflex www.indiandentalacademy.com
  • 59. Clasp knife reflex or autogenic inhibition Functional significance- protect the overload by preventing damaging contraction www.indiandentalacademy.com
  • 60. Mechanism of Orofacial Pain Pain is the physical sensation associated with injury or disease Nociception – noxious stimulus originating from sensory receptor. Pain – unpleasant sensation perceived in the cortex, usually as a result of incoming nociceptive input Suffering- how the human reacts to the perception of pain Pain behaviour- individuals audible & visible actions that communicate suffering to others www.indiandentalacademy.com
  • 61. Types of pain  Differentiate between site & source 1. Primary pain 2. Heterotopic pain a. Central pain eg brain tumors b. Projected pain eg. Entrapment of cervical nerve c. Referred pain eg myocardial infarction  3 clinical rules  Passing from one branch to another in a laminated manner okeson 1995  Sometimes outside the nerve – moves cephalad not caudal  In head neck region never crosses the midline www.indiandentalacademy.com
  • 63. 2) MUSCLES To propel human skeleton there are 639 muscles,6 billion muscle fibers. Each fiber has 1000 fibrils…so at 1 time or another there are 6000 billion fibrils at work. Two important physical properties- Elasticity – F = AE D L Contraction www.indiandentalacademy.com
  • 64. MUSCLE FUNCTION:- The entire muscle has three potential functions:- Isotonic contraction (e.g)-The masseter contracts to elevate the mandible forcing the teeth through a bolus of food Isometric contraction- When a number of motor unit contract opposing a given force the function of muscle is to stabilize the jaw. This contraction without shortening is called Isometric contraction (e.g occurs in the masseter when an object is held between the teeth (pen). Controlled relaxation-When stimulation of the motor unit is discontinued, the fibers of the motor unit relax & return to their normal length. (e.g).In the masseter when the mouth opens to accept the new bolus of food during masticationwww.indiandentalacademy.com
  • 65. Eccentric contraction – at the precise moment of motor vehicle accident, the cervical muscles contract to support the head & resist movement. If the impact is great sudden changes in inertia of head causes it to move while the muscles contract trying to support it. The result is sudden lengthening of muscles while they are contracting www.indiandentalacademy.com
  • 66. Fig. 5. Lateral cephalometric tracings of mandible in open-mouth (1) and postural resting (2) positions, occlusion (3), and overclosure (4). Positional influence of mandible on strength of muscle contraction is shown by the fact that between 2 and 3 the greatest force is created. Magnitude falls off rapidly between 3 and 4. Resting length www.indiandentalacademy.com
  • 67. Muscle strength Maximum force of muscle when all its fibers are stimulated to ‘fire’ Summation of contractions= 4 x ‘single contraction’ Muscle strength is directly proportional to cross sectional area i.e 3 to 10 kg per square centimeter of cross section (Ganong in 1971) www.indiandentalacademy.com
  • 68. Principles of muscle physiology Best way to visualize innervaion of muscle is by use of an electromyogram. 1. All or none law- Sherrington in 1947 pointed out that individual fibers have no variable contraction status, but are either relaxed or going into maximum contraction by virtue of adequate stimulus. Strength of muscle will depend on- frequency of stimuli & no. of fibers involved Not present during muscle fatigue (Merton in 1956) 2. Muscle tonus 3. Resting length 4. Myotatic reflex 5. Reciprocal innervation & inhibition- Sherrington in 1947www.indiandentalacademy.com
  • 69. Reciprocal Innervation: For the mandible to be elevated by the temporal, medial pterygoid, or masseter muscles must contract while the suprahyoid muscles must relax and lengthen. The neurologic controlling mechanism for the antagonistic groups is known as reciprocal innervation. www.indiandentalacademy.com
  • 70. • MOTOR UNIT:  When the neuron are activated the motor end plate is stimulated to release small amounts of acetylcholine.  This initiates depolarization of the muscle fibres and causes the muscle fibers to shorten or contract.  A single motor neuron may innervate only few muscle fibers or more (e.g):inferior lateral pterygoid & masseter www.indiandentalacademy.com
  • 72. Antagonistic mechanism of muscles:- www.indiandentalacademy.com
  • 74. A small change in the TMJ may cause Pathology PVD & OVD disharmony- Effect on temporalis & masseter Overclosure with excessive retrusive activity of posterior temporalis fibers along with masseter Pterygoid muscle under constant tension causes repeated stretch reflex & spasms(Graber TM 1969) This holds the disc anteriorly while condyles push it posteriorly & upwards. So a click while condyle rides over the posterior periphery of disc followed by impingement of postauricular connective tissue This condition may be mistaken for arthritis. Shore feels that clicking or popping in TMJ is because of jumping forward of condyle a fraction of second ahead of disc www.indiandentalacademy.com
  • 75. Major functions of masticatory system 1. Mastication 2. Swallowing 3. speech www.indiandentalacademy.com
  • 76. Mastication Fletcher summarizes his work on masticatory stroke in the adult, using the six phases outlined by Murphy. a) The preparatory phase In which food ingested and positioned by the tongue with in the oral cavity and the mandible is moved towards chewing side. b) Food contact It is characterized by a momentary hesitation in movement. This Fletcher interpreted to be a pause triggered by sensory receptors concerning the apparent viscosity of the food and probable trans-articulator pressures incident to chewing. c) The crushing phase If starts with high velocity then slows as the food is crushed and packed. d) Tooth contact Accomplished by a slight change in direction but not delay. According to Murphy all reflex adjustments of the musculature for tooth contact are completed in the crushing phase before actual contact is made.This was supported by Moller in 1966 www.indiandentalacademy.com
  • 77. e) The grinding phase  Which coincides with transgression of the mandibular molars across there maxillary counterparts and is therefore highly constant from cycle to cycle. Messerman in 1963 termed this phase the terminal functional orbit.  Ahelgren noted that during this phase the bilateral musculature discharge becomes unequal and asynchronous indicating that the person is chewing unilaterally. f) Centric occlusion  When movement of the teeth comes to a definite and distinct stop at a single terminal point from which the preparatory phase of next stroke begins. www.indiandentalacademy.com
  • 78. Mastication Chewing stroke- Frontal view 16-18 mm 5-6mm 3mm vertical 3-4 mm lateral www.indiandentalacademy.com
  • 79. Although mastication occurs bilaterally, about 78% of observed subjects have a preferred side where the majority of chewing occurs (pond & Barghi) This normally is the side with the greatest number of tooth contacts during lateral glide Chewing on one side leads to unequal loading of TMJ Average length of time for tooth contact during mastication is 194 msec (Suit,Gibbs & Benz) www.indiandentalacademy.com
  • 80. Tooth contacts during mastication  Two types- 1. Gliding 2. Single contact  Mean percentage of gliding contacts during chewing- 60% during grinding phase & 50 % during opening phase (Suit,Gibbs & Benz) www.indiandentalacademy.com
  • 83. When the posterior teeth contact in undesirable lateral movement, the malocclusion produces an irregular & less repeatable chewing stroke (Suit,Gibbs & Benz) Marked difference between chewing strokes of normal persons & TMJ patients (Mongini, Tempia- Valenta www.indiandentalacademy.com
  • 84. Andersen 1956- relation of chewing stroke with different food consistency According to Gibbs harder the food the more lateral the closure strokes become The harder the food the more chewing strokes needed (Horio & kawamura ) www.indiandentalacademy.com
  • 86. Forces of mastication Males Female’s max biting load range- 79- 99 pounds( 35.8- 44.9 kg) Male’s- 118-142 pounds(53.6- 64.4 kg) by Berkhaus in 1941 The greatest maximum biting force reported is 975 pounds(443 kg) by Gibbs et al in 1985 Molars- 91-198npounds(41.3- 89.8 kg) Central incisors- 13.2- 23.1 kg) by Howell & Manly in 1948  With age up adolescence (Garner, Kotwal, Worner, Andersen 1944, 1973) Can be increased with practice & exercise www.indiandentalacademy.com
  • 87. In a study done by Gibbs et al in 1981 reported grinding phase of closure stroke averaged 58.7 pounds on posterior teeth- about 36.2 % subjects maximum biting force Bakke & mischler in 1991- tooth pain reduces amount of force used during chewing According to a study done by Ramjford in 1961 when teeth contact evenly & simultaneously in the retruded position, the muscles of mastication have decreased activities & more harmonious during mastication www.indiandentalacademy.com
  • 88. Role of tongue in mastication www.indiandentalacademy.com
  • 89. Deglutition It is a series of coordinated muscle contractions that moves a bolus of food from the oral cavity through the esophagus to the stomach It consists of voluntary, involuntary & reflex muscular activities www.indiandentalacademy.com
  • 90. Stabilization of mandible is an important part of swallowing Somatic swallow- teeth for mandibular stability The average tooth contact during swallowing lasts about 683 msec 3x longer than mastication (Suit,Gibbs & Benz 1975) Force applied = 66.5 pounds- 9.8 pounds more than mastication (Suit,Gibbs & Benz 1975) Infantile or visceral swallow- mandible is braced by placing tongue forward & between dental arches or gum pads www.indiandentalacademy.com
  • 91. Phases of deglutition by Fletcher Preparatory phase www.indiandentalacademy.com
  • 93. Pharyngeal stage & Velopharyngeal mechanism www.indiandentalacademy.com
  • 94. • ACTION OF THE VELOPHARYNGEAL VALVE • ETIOLOGY o absence of structure (e.g., cleft palate), o disproportion of structure (e.g.. short palate, deep nasopharynx, short functional palate). o neurologic defects (e.g., muscle or central nervous system) VELOPHARYNGEAL INCOMPETENCE www.indiandentalacademy.com
  • 98. Fig. 14. Bar graph illustrating comparative muscle pressures during the normal swallowing act. Only lateral and medial pterygoid, middle temporalis, and anterior and posterior masseter fibers show moderate activity. The remainder demonstrate slight activity. www.indiandentalacademy.com
  • 99. Fig. 15. Bar graph illustrating comparative muscle pressures associated with abnormal swallowing. Note heavy mentalis and lip activity, dominance of posterior temporalis and masseter fibers, and increased hyoid muscle action. (See Fig. 14.) www.indiandentalacademy.com
  • 100. Frequency of swallowing Flanagan et al in 1963 demonstrated swallowing cycle occurs 590 times during 24 hr period : 146 cycles during eating 394 cycles between meals while awake 50 cycles during sleep www.indiandentalacademy.com
  • 101. Speech: Speech is an expression of thoughts by production of articulate sound, bearing a definite meaning. It is very sophisticated, autonomous, & unconscious activity Its production involves neural, muscular, mechanical, aerodynamic, acoustic, & auditory factors It is one of the highest functions of brain It is brought about by the coordinated activity of different parts of brain, particularly the motor & sensory www.indiandentalacademy.com
  • 102. It occurs when a volume of air is forced from the lungs by diaphragm through the larynx & the oral cavity Vocal cords create sounds with desired pitch & then precise form assumed by mouth determines the resonance & exact articulation of sound Expiration & inspiration www.indiandentalacademy.com
  • 103. Mechanism of speech: Speech depends upon the coordinated activities of central & peripheral speech apparatus The central speech apparatus consists of higher centres- the cortical & subcortical centres The peripheral speech apparatus includes larynx, pharynx, mouth, nasal cavities, tongue, & lips www.indiandentalacademy.com
  • 104. Speech production; structural & functional demands: Controlling airstream that is initiated in the lungs & passes through the larynx & vocal cords produces all speech sounds Adjustments in the airflow contribute to variations of pitch & intensity of the voice The structural controls for the speech sounds are the various articulations or valves made in pharynx & the oral & the nasal cavities www.indiandentalacademy.com
  • 105. Each sound is affected by the length, diameter & elasticity of the vocal tract & by the locations of constrictors along its length Because nearly all speech sounds are emitted from the mouth, the nasopharynx is closed off from the oropharynx during speech Closure is performed by an upward lift of the soft palate Intimacy of the pharyngeal wall contact, as well as magnitude of movement by the soft palate, varies with the nature & sequence of the speech sounds www.indiandentalacademy.com
  • 106. As the outgoing air passes through the mouth, tongue, lips, & mandibular oscillations modify it. The tongue has a critical impact on speech production & needs optimal mobility to lift, protrude, flatten, forms a groove & contact adjacent tissues freely. Jaw and tooth relationship enable the tongue to articulate against the maxillary teeth or alveolus. www.indiandentalacademy.com
  • 107. The 1st speech sounds are the bilabial sounds ‘m, p & b’ Somewhat later the tongue tip consonants like ‘t’ & ‘d’ appear The sibilant ‘s’ and ‘z’ sounds which require that the tongue tip be placed close to but not against the palate, come later still & the last speech sound ‘r’ which requires precise positioning of the posterior tongue, often is not acquired until age 4-5 Tongue & palate for ‘d’ Articulations of sound www.indiandentalacademy.com
  • 109. Speech difficulties related to malocclusion: s,z (sibilants) - Ant. Open bite, large gap between incisors t,d (Linguoalveolar stops) - Irregular incisors f,v (Labiodental fricatives) - Skeletal class III th,sh,ch (linguodental fricatives) - Anterior open bite www.indiandentalacademy.com
  • 110. Lisping This speech defect involves change of sound of letters and wards. Etiology Main cause is continuity of infantile mode of speech. If the tongue is moved forward without mandible and lies on top of lower incisors lisping may result. Certain malocclusions like openbite, maxillary protrusion, mandibular retrusion and malaligned tooth also cause lisping. Stammering In stammering the child fails to produce any sound for sometime. These create emotional tension and difficulty in social adjustment. Etiology Hereditary Due to emotional tension Lack of balance among two hemispheres of the brain. Auditory amnesia www.indiandentalacademy.com
  • 114. BUCCINATOR MECHANISMBUCCINATOR MECHANISM Winders has shown that during mastication & deglutition tongue exerts 2-3 times as much force on dentition as lips & cheeks at 1 time Sphincter like Purse string effect www.indiandentalacademy.com
  • 115. 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
  • 116. Absence of buccinator mechanism www.indiandentalacademy.com
  • 118. 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 Leads to development of malocclusion like maxillary anterior protrusion, open bite and narrowing of maxillary arch. www.indiandentalacademy.com
  • 119. Mature tongue posture: During mandibular posture, the dorsum touches the palate slightly and the tongue tip normally is at rest in the lingual fossa or at the crevices of the mandibular incisors. www.indiandentalacademy.com
  • 120. Abnormal tongue posture:  Retracted tongue posture  Protracted tongue posture( Retained infantile tongue posture) www.indiandentalacademy.com
  • 121. Fig. 1. Normal structural relationship. Note proximity of tongue and palate; gentle, un-strained lip contact; normal overbite and overjet. Fig. 20. Sagittal section illustrating Class II, Division 1 relationship.Note lowered tongue posture, narrowed buccal dental segments in maxillary arch, and lower lip cushioning to lingual aspect of maxillary incisors during rest and active function. Lip and tongue team up to accentuate deformity.www.indiandentalacademy.com
  • 122. Fig. 26. Tongue and lip adaptation to Class III malocclusion. Relatively functionless lower lip in marked contrast to excessive activity associated with Class II, Division 1 malocclusion. Lower tongue position is similar, but with no anterior thrust on deglutition. Greater upper lip activity is in evidence in the attempt to "close off" during swallowing. www.indiandentalacademy.com
  • 123. FRANKEL PHILOSOPHY Frankel believes that active muscle & tissue mass has a potential restraining effect on the outward development of the dental arches Abnormal perioral musculature exerts a deforming action that prevents full accomplishment of the optimal growth & development pattern Frankel visualizes his vestibular constructions as “ought to be” matrix that allows the muscles to exercise & adapt. www.indiandentalacademy.com
  • 124. CPG & MUSCLE ENGRAM Within the brainstem is a pool of neurons that controls rhythmic muscle activities. This pool of neurons is collectively known as central pattern generator (CPG) For precise timing of activity With the feedback information that allows CPG to determine the most appropriate & efficient chewing stroke It becomes a learned pattern & is repeated. This learned pattern is muscle engram www.indiandentalacademy.com
  • 125. SUMMARY AND CONCLUSION Before the orthodontist appreciates abnormal functions of the oro-facial muscles he must have a knowledge of their normal development and maturation. A malocclusion is dynamic balance at that particular time. In Orthodontics whenever a patient comes his teeth will be in the most stable position with the contiguous structures As form is related to function, the function should be corrected for achieving the best form & stability in the long runwww.indiandentalacademy.com
  • 126. BIBLIOGRAPHY Jeffrey P.Okeson management of temporomandibular disorders and occlusion,5th edition, 29-44,93-107. Major M. Ash, Sigurd Ramfjord; Occlusion; 4th edition;164-168.  Aurthr C Gyton, John E Hall; text book of medical physiology; 9th edition; W.B. Saunders; pg 803-805, 1048-1050 Robert E Moyers; Handbook of orthodontics; 4th edition;year book medical publishers; pg 84-85, 173- 174, 203-205, 209-212), GraberVolume The "three M's": Muscles, Malformation and Malocclusion,1963 Jun (418 - 450): www.indiandentalacademy.com
  • 127.  T.M.Graber; Thomas Rakosi; Alexander Petrovic; Dentofacial orthopedic with functional appliance;2nd edition, mosby; pg 143-145, 126-130.  T.M.Graber; Bedrich Neumann; Removable orthodontic appliances; 2nd edition; W.B.saunders company; pg 145- 154, 167-169.  Chien-Lun Peng, DDS, PhD,a Paul-Georg Jost-Brinkmann, Priv Doz, Dr med dent,b Noriaki Yoshida, DDS,PhD,c Hsin- Hua Chou, DDS, PhD,d and Che-Ton Lin, DDS, PhDe,Comparison of tongue functions between mature and tongue-thrust swallowing—an ultrasound investigation, American Journal of Orthodontics and Dentofacial Orthopedics,Volume 125, Number 5  William R Profitt; contemporary orthodontics; 4th edition; mosby Elsevier publication; pg 84-86.  K Sembulingam, Prema Sembulingam; essentials of medical physiology; 4th edition; jaypee brothers; pg 244- 246, 847-848.  George A Zarb, Charles L Bolender; prosthodontic treatment for edentulous patients;12th edition; Mosby Elsevier publication; pg 379-385.www.indiandentalacademy.com