Muscle physiolgy/ oral surgery courses

MuscleMuscle
physiologyphysiology
INDIAN DENTAL ACADEMY
Leader in continuing Dental Education
www.indiandentalacademy.com

TO GODTO GOD
 ………….THE ARCHITECT OF OUR MUSCULO.THE ARCHITECT OF OUR MUSCULO
SKELETAL SYSTEM.THE MORE WESKELETAL SYSTEM.THE MORE WE
UNDERSTAND THE LOGIC BEHIND ITSUNDERSTAND THE LOGIC BEHIND ITS
BEUTIFULLY INTEGRATED DESIGN,THEBEUTIFULLY INTEGRATED DESIGN,THE
MORE WE REALIZE ITS EVERY ELEMENT WASMORE WE REALIZE ITS EVERY ELEMENT WAS
PLANNED BY A LOVING CREATOR.PLANNED BY A LOVING CREATOR.
 THE WORDS OF AFFECTION WE SPEAK,THETHE WORDS OF AFFECTION WE SPEAK,THE
SMILES WE SHARE, THE SONGS WE SING ARESMILES WE SHARE, THE SONGS WE SING ARE
POSSIBLE ONLY BECAUSE AN ELEMENT OFPOSSIBLE ONLY BECAUSE AN ELEMENT OF
LOVE WAS INTEGRATED INTO THIS DESIGNLOVE WAS INTEGRATED INTO THIS DESIGN

CONTENTS OF THE SEMINAR:
 Introduction.
 Classification of
muscles.
 Structure of skeletal
muscle.
 Microscopic study of
skeletal muscle.
 Sarcomere.
 Contractile elements of
muscle.
 Sarcotubular system.
 Composition of muscle.
 Properties of skeletal
muscles.
 Changes during
muscular contraction.
 Neuromuscular
junction.
 Electromyogram and
disorders of muscles.
 References from
journals.
 Bibliography.

IntroductionIntroduction
 Muscle is an organ specializing in theMuscle is an organ specializing in the
transformation of chemical energy intotransformation of chemical energy into
movement. Movement is essential to life, andmovement. Movement is essential to life, and
takes many forms, from cytoplasmic streamingtakes many forms, from cytoplasmic streaming
to the growth of neurones at the cellular level &to the growth of neurones at the cellular level &
to the long distance flight of the albatross or theto the long distance flight of the albatross or the
explosive performance of a sprinter.explosive performance of a sprinter.

Definition of muscleDefinition of muscle
 Muscle can be defined as an organ or tissue thatMuscle can be defined as an organ or tissue that
by contraction produces movement of an animalby contraction produces movement of an animal
oror
 A tissue composed of contractile cells or fibersA tissue composed of contractile cells or fibers
that affect the movement of an organ or part ofthat affect the movement of an organ or part of
the bodythe body

Classification of musclesClassification of muscles
 Basis of classification-Basis of classification-
11 Depending upon striations.Depending upon striations.
a) striated b)non-striateda) striated b)non-striated
22 Depending upon control.Depending upon control.
a) voluntary b)involuntary muscles.a) voluntary b)involuntary muscles.
33 Depending upon the function.Depending upon the function.
a) skeletal muscle b)cardiac muscle c)smootha) skeletal muscle b)cardiac muscle c)smooth
muscle.muscle.

COMPOSITION OF MUSCLECOMPOSITION OF MUSCLE
THE SKELETAL MUSCLE IS MAINLY MADE UP OF 75%THE SKELETAL MUSCLE IS MAINLY MADE UP OF 75%
WATER,20%PROTEINS AND 5% OF ORGANICWATER,20%PROTEINS AND 5% OF ORGANIC
SUBSTANCES.SUBSTANCES.
PROTEINS PRESENT IN THE MUSCLE AREPROTEINS PRESENT IN THE MUSCLE ARE
1.1. MYOSINMYOSIN
2.2. ACTINACTIN
3.3. TROPOMYOSINTROPOMYOSIN
4.4. TROPONINTROPONIN
5.5. MYOGENMYOGEN
6.6. MYOGLOBINMYOGLOBIN

ORAGANIC SUBSTANCESORAGANIC SUBSTANCES
 CARBOHYDRATESCARBOHYDRATES-GLYCOGEN AND-GLYCOGEN AND
HEXOPHOSPHATE.HEXOPHOSPHATE.
 LIPIDSLIPIDS-NEUTRAL-NEUTRAL
FATS,CHOLESTEROL,STEROIDS.FATS,CHOLESTEROL,STEROIDS.
 NITROGENOUS SUBSTANCESNITROGENOUS SUBSTANCES LIKELIKE
ATP,CREATINE,UREA,URIC ACID.ATP,CREATINE,UREA,URIC ACID.

INORGANIC SUBSTANCESINORGANIC SUBSTANCES
 CATIONSCATIONS--POTASSIUM IS THE PRINCIPLE MINERALPOTASSIUM IS THE PRINCIPLE MINERAL
OF THE MUSCLE.THE OTHER CATIONS PRESENT AREOF THE MUSCLE.THE OTHER CATIONS PRESENT ARE
SODIUM,CALCIUM,AND MAGNESIUMSODIUM,CALCIUM,AND MAGNESIUM..
 ANIONSANIONS--CHLORIDES,PHOSPHATES ANDCHLORIDES,PHOSPHATES AND
SULFATES.SULFATES.

Functions of the muscle.Functions of the muscle.
 Through sustained contraction & relaxation theThrough sustained contraction & relaxation the
muscle has three key functionsmuscle has three key functions..
 MotionMotion-these movements rely on integrated functioning of-these movements rely on integrated functioning of
bones, joints and skeletal muscles.bones, joints and skeletal muscles.
 Stabilizing the body positions & regulating theStabilizing the body positions & regulating the
organ volumeorgan volume -- Besides producing movements skeletalBesides producing movements skeletal
muscles contract to maintain the body in stable positions likemuscles contract to maintain the body in stable positions like
standing or sitting.standing or sitting.
 Thermogeneis or generation heatThermogeneis or generation heat-- as skeletal musclesas skeletal muscles
contract to perform work & the byproduct is heat which is usedcontract to perform work & the byproduct is heat which is used
to maintain the body temperature. Muscle contractions generateto maintain the body temperature. Muscle contractions generate
as much as 85% of all the body heat.as much as 85% of all the body heat.

STRUCTURE OF THE SKELETAL MUSCLE

Microscopic Structure of the muscleMicroscopic Structure of the muscle
fibers.fibers.

Types of muscle fibersTypes of muscle fibers
 Muscle fibers that have high content of myoglobinMuscle fibers that have high content of myoglobin
are termed asare termed as red muscle fibersred muscle fibers and those whichand those which
have low content of myoglobin are termed ashave low content of myoglobin are termed as whitewhite
muscle fibersmuscle fibers..
 Slow oxidative type I fibersSlow oxidative type I fibers--
 these fibers also called as slow twitch orthese fibers also called as slow twitch or
fatigue resistant fibers contain large amountsfatigue resistant fibers contain large amounts
of myoglobin & have a high capacity toof myoglobin & have a high capacity to
generategenerate ATP by aerobic system, these fibersby aerobic system, these fibers
are very resistant to fatigue.are very resistant to fatigue.

Fast oxidative type IIA fibersFast oxidative type IIA fibers--
These fibers are called as fast twitch fibersThese fibers are called as fast twitch fibers
or fatigue resistant fibers have a low myoglobin contentor fatigue resistant fibers have a low myoglobin content
and are red having a high capacity for generating ATP byand are red having a high capacity for generating ATP by
oxidative process, these are resistant to fatigue but notoxidative process, these are resistant to fatigue but not
as type I fibers.as type I fibers.
Fast glycolytic type IIB fibersFast glycolytic type IIB fibers--
These fibers also called as fast twitch orThese fibers also called as fast twitch or
fatigable fibers have low myoglobin content and containfatigable fibers have low myoglobin content and contain
large amounts of glycogen & generatelarge amounts of glycogen & generate ATPATP by anaerobicby anaerobic
pathway which is not sufficient for the skeletal fibers &pathway which is not sufficient for the skeletal fibers &
these get fatigued easilythese get fatigued easily..

Muscle spindlesMuscle spindles
 Muscle spindle is anMuscle spindle is an
encapsulatedencapsulated
proprioceptor whichproprioceptor which
detects changes in lengthdetects changes in length
of the muscle.of the muscle.
 The muscle spindlesThe muscle spindles
accomplish theaccomplish the
coordinated movements ofcoordinated movements of
the jaw& the muscles ofthe jaw& the muscles of
mastication by relayingmastication by relaying
constant feedback of theconstant feedback of the
mandibular position to themandibular position to the
trigeminal nuclei of thetrigeminal nuclei of the
brain stem.brain stem. www.indiandentalacademy.com

CHARECTERISTICS OF MUSCLE TISSUE
THE MUSCLE TISSUE HAS FOUR PRINCIPLE CHARETERISTICS THAT
ENABLE IT TO CARRY OUT ITS FUNCTIONS.
1.EXCITABILITY-IS THE ABILITY TO RESPOND TO CERTAIN STIMULI BY
PRODUCING ELECTRICAL SIGNALS CALLED AS ACTION POTENTIALS.
2.CONTRACTILTIY-IS THE ABILITY OF MUSCLE TISSUE TO SHORTEN
AND THICKEN THUS GENERATING FORCE TO DO WORK.MUSCLE
CONTRACTS IN RESPONSE TO ONE OR MORE ACTION POTENTIALS.
3.EXTENSIBILITY-MEANS THAT THE MUSCLE CAN BE STRETCHED
WITHOUT DAMAGING THE TISSUE.
4.ELASTICITY-MEANS THAT THE MUSCLE TISSUE TENDS TO RETURN
BACK TO ITS ORIGINAL SHAPE AFTER CONTRACTION OR EXTENSION.

Sarcotubular systemSarcotubular system
 The myofibrilsThe myofibrils
embedded in theembedded in the
sarcoplasm of the musclesarcoplasm of the muscle
are surrounded by someare surrounded by some
important structuresimportant structures
which appear as vesicleswhich appear as vesicles
& tubules in electron& tubules in electron
microscope ,thesemicroscope ,these
structures are togetherstructures are together
called as sarcotubularcalled as sarcotubular
system.system.

Functions of sarcotubular systemFunctions of sarcotubular system
 TheThe T-tubulesT-tubules are responsible for rapidare responsible for rapid
transmission of impulse in the form of actiontransmission of impulse in the form of action
potential from sarcolemma to the myofibrils.potential from sarcolemma to the myofibrils.
 TheThe L-tubulesL-tubules store a large quantity of calciumstore a large quantity of calcium
ions ,when the action potential reaches theions ,when the action potential reaches the
L-tubule .These calcium ions are immediatelyL-tubule .These calcium ions are immediately
released into the sarcoplasm and these ionsreleased into the sarcoplasm and these ions
trigger the processes involved in the contractiontrigger the processes involved in the contraction
of the muscle.of the muscle.

SarcomereSarcomere
 Sarcomere is the structural &Sarcomere is the structural &
functional unit of the skeletalfunctional unit of the skeletal
system.system.
 Each sarcomere extendsEach sarcomere extends
between two Z-lines. Thusbetween two Z-lines. Thus
each myofibril contains manyeach myofibril contains many
sarcomeres arranged in seriessarcomeres arranged in series
throughout the length of thethroughout the length of the
myofibril.myofibril.
 Each myofibril consists ofEach myofibril consists of
alternate A-band & I-band.alternate A-band & I-band.
 In the relaxed state theIn the relaxed state the
average length of eachaverage length of each
sarcomere is 2-3 microns.sarcomere is 2-3 microns.

Electronic microscopic study of sarcomereElectronic microscopic study of sarcomere
 The sarcomere consists ofThe sarcomere consists of
many thread like proteinmany thread like protein
filaments, these are called asfilaments, these are called as
myofilaments & are of 3myofilaments & are of 3
typestypes
1.1. Actin filamentsActin filaments
2.2. Myosin filaments.Myosin filaments.
3.3. Titin filamentsTitin filaments
 Actin filaments are thinActin filaments are thin
filaments & are 20Afilaments & are 20Aoo
thick &thick &
1micron in length.1micron in length.
 Myosin filaments are thickMyosin filaments are thick
filaments which are 115Afilaments which are 115AOO
thick & 1.5micron in length.thick & 1.5micron in length.

PROPERTIES OF SKELETALPROPERTIES OF SKELETAL
MUSCLEMUSCLE
1.Excitability-1.Excitability- The reaction or response of a tissue to irritation orThe reaction or response of a tissue to irritation or
stimulus.stimulus.
2.Stimulus-2.Stimulus-
a)a) Minimal stimulusMinimal stimulus-the stimulus which is sufficient to excite the tissue is-the stimulus which is sufficient to excite the tissue is
called minimal stimulus.called minimal stimulus.
b)b) Sub minimal stimulus-Sub minimal stimulus-the stimulus which cannot excite the tissue isthe stimulus which cannot excite the tissue is
called sub minimal stimulus.called sub minimal stimulus.
3.Chronaxie3.Chronaxie-is the minimum time, at which a stimulus with double the-is the minimum time, at which a stimulus with double the
rheobasic strength can excite the tissue.rheobasic strength can excite the tissue.
4.Types of contraction-4.Types of contraction-
a)a) Isotonic contractionIsotonic contraction-results in over all shortening of the muscle under-results in over all shortening of the muscle under
constant load.constant load.
Eg-isotonic contraction occurs in the masseter when the mandible isEg-isotonic contraction occurs in the masseter when the mandible is
elevated forcing the teeth trough a bolus of food.elevated forcing the teeth trough a bolus of food.
b)b) Isometric contractionIsometric contraction-is contraction of the muscle without shortening,-is contraction of the muscle without shortening,
seen in the masseter when an object is held between the teeth.seen in the masseter when an object is held between the teeth.

CHANGES DURING MUSCULAR
CONTRACTION
 Resting membrane potentialResting membrane potential -is the potential difference-is the potential difference
between the inside & outside of the cell under restingbetween the inside & outside of the cell under resting
conditions.conditions.
 Action potential -Action potential - when the muscle is stimulated a series ofwhen the muscle is stimulated a series of
changes occur in the muscle fiber which is called as actionchanges occur in the muscle fiber which is called as action
potential & occurs in two phasespotential & occurs in two phases
1.1. DepolarizationDepolarization - when the impulse reaches the muscle the- when the impulse reaches the muscle the
polarized condition( - 90mv) is altered i.e. the membranepolarized condition( - 90mv) is altered i.e. the membrane
potential is abolished. The interior of the muscle becomespotential is abolished. The interior of the muscle becomes
+ve & outside –ve leading to depolarization.+ve & outside –ve leading to depolarization.
2.2. Repolarization -Repolarization - within short time the muscle regains thewithin short time the muscle regains the
resting membrane potential by the process of repolarization.resting membrane potential by the process of repolarization.

Ionic basis of muscular contractionIonic basis of muscular contraction
 THE IONIC IMBALANCETHE IONIC IMBALANCE
IS PRODUCED MAINLYIS PRODUCED MAINLY
BY TWO TRANSPORTBY TWO TRANSPORT
MECHANISMS IN THEMECHANISMS IN THE
CELL MEMBRANECELL MEMBRANE
 1.SODIUM POTASSIUM1.SODIUM POTASSIUM
PUMPPUMP
 2.SELECTIVE2.SELECTIVE
PERMEABILITY OF THEPERMEABILITY OF THE
CELL MEMBRANE.CELL MEMBRANE.

Ionic basis of muscular contractionIonic basis of muscular contraction
 Sodium potassium pumpSodium potassium pump
 There is active transport ofThere is active transport of
sodium & potassium acrosssodium & potassium across
the cell membrane by meansthe cell membrane by means
of Sodium potassium pump.of Sodium potassium pump.
 It moves 3 Na ions out of theIt moves 3 Na ions out of the
cell and 2 Kcell and 2 K++
ions inside theions inside the
cell by using energy fromcell by using energy from
ATP.ATP.
 Since more +ve ions areSince more +ve ions are
pumped outside the cell thanpumped outside the cell than
inside ,a net deficit of +veinside ,a net deficit of +ve
ions occurs inside the cell.ions occurs inside the cell.
 Selective permeability ofSelective permeability of
cell.cell.
 It occurs through theIt occurs through the
transport channels for thetransport channels for the
movement of specific ions.movement of specific ions.
 These are NaThese are Na++
,Cl,Cl--
and Kand K++
ions.ions.
 The NaThe Na++
,and Cl,and Cl--
are moreare more
outside and Koutside and K++
ions are moreions are more
inside the cell membrane.inside the cell membrane.

Changes in actomyosin complexChanges in actomyosin complex
 In the relaxed state the thinIn the relaxed state the thin
filaments from the oppositefilaments from the opposite
sides of the sarcomere aresides of the sarcomere are
away from each other leavingaway from each other leaving
a broad H-band.a broad H-band.
 During contraction of theDuring contraction of the
muscle the actin filamentsmuscle the actin filaments
glide over the myosinglide over the myosin
filaments formingfilaments forming
actomyosin complex..actomyosin complex..
 When the muscle shortensWhen the muscle shortens
further the opposite ends offurther the opposite ends of
the sarcomere approach eachthe sarcomere approach each
other so the H-zone becomesother so the H-zone becomes
narrow and the two Z-linesnarrow and the two Z-lines
come closer together withcome closer together with
reduction the length of thereduction the length of the
sarcomere.sarcomere. www.indiandentalacademy.com

ACTOMYOSIN COMPLEX INACTOMYOSIN COMPLEX IN
CONTRACTION PHASECONTRACTION PHASE

MOTOR UNITMOTOR UNIT
 THE SINGLE MOTORTHE SINGLE MOTOR
NEURON ITS AXONNEURON ITS AXON
TERMINALS AND THETERMINALS AND THE
MUSCLE FIBERSMUSCLE FIBERS
INNERVATED BY IT AREINNERVATED BY IT ARE
TOGETHER ARETOGETHER ARE
CALLED AS MOTORCALLED AS MOTOR
UNITUNIT
 THE NUMBER OFTHE NUMBER OF
MUSCLE FIBERS INMUSCLE FIBERS IN
EACH MOTOR UNITEACH MOTOR UNIT
VARIES ACCORDING TOVARIES ACCORDING TO
THE FUNCTION OF THETHE FUNCTION OF THE
MUSCLE.MUSCLE.

Neuromuscular junctionNeuromuscular junction The junction between theThe junction between the
terminal branch of the nerveterminal branch of the nerve
fiber & the muscle fiber isfiber & the muscle fiber is
called as the neuromuscularcalled as the neuromuscular
junction.junction.
 Each terminal branch of theEach terminal branch of the
nerve fiber is called as axonnerve fiber is called as axon
terminal.terminal.
 The membrane of the nerveThe membrane of the nerve
ending is called asending is called as
presynaptic membrane & thepresynaptic membrane & the
membrane of the fiber ismembrane of the fiber is
called as postsynapticcalled as postsynaptic
membrane.membrane.
 The space between the two isThe space between the two is
called as synaptic cleft whichcalled as synaptic cleft which
contains vesicles of Ach.contains vesicles of Ach.

Release of acetyl cholineRelease of acetyl choline
 Action potentialAction potential
 Axon terminalAxon terminal
 Opening of voltage gatedOpening of voltage gated
Ca+ channelsCa+ channels
 Entry of Ca+ ionsEntry of Ca+ ions
 Opening of vesicles &Opening of vesicles &
 Release of achRelease of ach

FATE OF ACETYL CHOLINEFATE OF ACETYL CHOLINE
 WITHIN ONE MILISECOND AFTER THEWITHIN ONE MILISECOND AFTER THE
RELEASE OF ACH INTO THE SYNAPTIC CLEFTRELEASE OF ACH INTO THE SYNAPTIC CLEFT
IT IS DESTROYED BY THE ENZYMEIT IS DESTROYED BY THE ENZYME
ACETYLCHOLINESTERASE.ACETYLCHOLINESTERASE.
 HOWEVER ACH IS SO POTENT THAT EVENHOWEVER ACH IS SO POTENT THAT EVEN
THIS SHORT DURATION OF 1 MILLISECOND ISTHIS SHORT DURATION OF 1 MILLISECOND IS
SUFFICIENT TO EXCITE THE FIBER.SUFFICIENT TO EXCITE THE FIBER.
 THE RAPID DESTRUCTION OF ACH HAS GOTTHE RAPID DESTRUCTION OF ACH HAS GOT
SOME IMPORTANT FUNCTIONALSOME IMPORTANT FUNCTIONAL
SIGNIFICANCE AS IT PREVENTS THESIGNIFICANCE AS IT PREVENTS THE
REPEATED EXCITATION OF THE MUCLEREPEATED EXCITATION OF THE MUCLE
FIBER .FIBER .

Relaxation of muscleRelaxation of muscle
 The relaxation of the muscle occurs when theThe relaxation of the muscle occurs when the
calcium ions are pumped back into thecalcium ions are pumped back into the
sarcoplasmic reticulum.sarcoplasmic reticulum.
 Hence the calcium ions enter the sarcoplasmicHence the calcium ions enter the sarcoplasmic
reticulum & the calcium content in thereticulum & the calcium content in the
sarcoplasm decreases leading to detachment ofsarcoplasm decreases leading to detachment of
calcium ions from the troponin.This causes thecalcium ions from the troponin.This causes the
release of myosin from actin and the musclerelease of myosin from actin and the muscle
relaxes.relaxes.

ElectromyogramElectromyogram
 The changes occurring in the electrical activityThe changes occurring in the electrical activity
of the muscle during voluntary movement canof the muscle during voluntary movement can
be recorded by using surface electrodes orbe recorded by using surface electrodes or
needle electrodes which are connected to anneedle electrodes which are connected to an
oscilloscope.oscilloscope.
 The procedure of recording the muscle actionThe procedure of recording the muscle action
potentials is called as electromyography.potentials is called as electromyography.

Disorders of muscles.Disorders of muscles.
Hypo tonicityHypo tonicity-Is decreased tone of the muscle and-Is decreased tone of the muscle and
the muscle offers little resistance to stretchthe muscle offers little resistance to stretch
which is called a flaccidity.which is called a flaccidity.
Hyper tonicityHyper tonicity-Occurs in cases of upper motor-Occurs in cases of upper motor
neuron lesion & there is exaggerated release ofneuron lesion & there is exaggerated release of
action potentials and the tone of the muscle isaction potentials and the tone of the muscle is
increased. The muscle offers high resistance toincreased. The muscle offers high resistance to
stretch and this is called as spasticity.stretch and this is called as spasticity.
 FibrillationFibrillation-Fine irregular contractions of-Fine irregular contractions of
individual muscle fibers .individual muscle fibers .

 Denervation hypersensitivityDenervation hypersensitivity-Abnormal-Abnormal
excitability of the muscle & increase inexcitability of the muscle & increase in
sensitivity to the circulating A-ch molecules.sensitivity to the circulating A-ch molecules.
 Myasthenia gravisMyasthenia gravis-This is due to the inability of-This is due to the inability of
neuromuscular junction to transmit impulsesneuromuscular junction to transmit impulses
from nerve endings to the muscle.from nerve endings to the muscle.
 Lambert Eaton syndromeLambert Eaton syndrome-In this condition-In this condition
muscle weakness is caused by antibodies againstmuscle weakness is caused by antibodies against
one of the Caone of the Ca++
channels in the nerve endings atchannels in the nerve endings at
the NMJ.This decreases the normal Cathe NMJ.This decreases the normal Ca++
influxinflux
that causes A-ch release.that causes A-ch release.

Local muscle disordersLocal muscle disorders
 Muscle splintingMuscle splinting - occurs due to protective co- occurs due to protective co
-contraction produced by CNS in response to injury or-contraction produced by CNS in response to injury or
threat of injury.threat of injury.
 Non inflammatory myalgiaNon inflammatory myalgia -is a local primary non-is a local primary non
inflammatory myogenous pain disorder in response toinflammatory myogenous pain disorder in response to
prolonged co - contraction.prolonged co - contraction.
 Trigger point myalgiaTrigger point myalgia -- myofascial pain in the regionalmyofascial pain in the regional
areas characterized by local areas of firm, hypersensitiveareas characterized by local areas of firm, hypersensitive
bands of muscle tissue known as trigger pointsbands of muscle tissue known as trigger points..
 Myositis or inflammatory myalgiaMyositis or inflammatory myalgia --inflammatoryinflammatory
condition within the muscle tissue.condition within the muscle tissue.

Age related changes in muscle.Age related changes in muscle.
 Beginning at about 30 years of age there isBeginning at about 30 years of age there is
progressive loss of skeletal mass that is largelyprogressive loss of skeletal mass that is largely
replaced by fat.replaced by fat.
 Accompanying the loss of muscle tissue there isAccompanying the loss of muscle tissue there is
a decrease in strength and slowing of musclea decrease in strength and slowing of muscle
reflexes.reflexes.

Muscle relaxation therapiesMuscle relaxation therapies
 Physical therapyPhysical therapy
modalities-modalities-
1.1. ThermotherapyThermotherapy
2.2. Coolant therapyCoolant therapy
3.3. Ultrasound therapyUltrasound therapy
4.4. IontophoresisIontophoresis
5.5. Electro galvanicElectro galvanic
stimulation therapystimulation therapy
66 Transcutaneous nerveTranscutaneous nerve
stimulationstimulation
77 AcupunctureAcupuncture
88 Cold laserCold laser
Manual techniques-Manual techniques-
1.1. Soft tissue mobilizationSoft tissue mobilization
2.2. Muscle conditioningMuscle conditioning
 Restricted useRestricted use
 Relaxation therapyRelaxation therapy
 Passive muscle stretchingPassive muscle stretching
 Resistance exercisesResistance exercises
 Clenching exercisesClenching exercises
 Postural exercisesPostural exercises
 Joint distractionJoint distraction

Muscle relaxation splintsMuscle relaxation splints
 Because of the intense natureBecause of the intense nature
of some types of muscleof some types of muscle
spasms it is extremelyspasms it is extremely
difficult to determine thedifficult to determine the
effect of muscle-effect of muscle-
incoordination.Thus the useincoordination.Thus the use
of occlusal splints forof occlusal splints for
deprogramming muscledeprogramming muscle
hyperactivity often has greathyperactivity often has great
advantage for diagnosticadvantage for diagnostic
purpose.purpose.
 The best and the most easilyThe best and the most easily
fabricated musclefabricated muscle
deprogrammer is the anteriordeprogrammer is the anterior
bite plane because itbite plane because it
discludes all the posteriordiscludes all the posterior
teeth.teeth. www.indiandentalacademy.com

Prosthodontic considerationsProsthodontic considerations
 The most common cause of medial pterygoid muscularThe most common cause of medial pterygoid muscular
spasm is repeated inferior alveolar nerve blocks.spasm is repeated inferior alveolar nerve blocks.
 The replacement of the mandibular posterior teethThe replacement of the mandibular posterior teeth
should be such that the long axis of the teeth should beshould be such that the long axis of the teeth should be
parallel to the medial pterygoid muscle for optimumparallel to the medial pterygoid muscle for optimum
functioning of the muscle & to prevent soreness of thefunctioning of the muscle & to prevent soreness of the
muscle.muscle.
 In cases of palatopharyngeal incompetancy seen inIn cases of palatopharyngeal incompetancy seen in
patients withpatients with myasthenia gravismyasthenia gravis a palatal lift prosthesisa palatal lift prosthesis
is given to seal the palatopharyngeal and oropharyngealis given to seal the palatopharyngeal and oropharyngeal
regionsregions

Pain in relation to muscles ofPain in relation to muscles of
masticationmastication
 Pain in the masseter may be due to occlusalPain in the masseter may be due to occlusal
disharmony, decreased vertical dimension ofdisharmony, decreased vertical dimension of
occlusion due to attrited posterior teeth, wornocclusion due to attrited posterior teeth, worn
out denture and resorption of the alveolar bone.out denture and resorption of the alveolar bone.
 The masseter muscle is the first to contract inThe masseter muscle is the first to contract in
persons who are in a state of intense emotionalpersons who are in a state of intense emotional
sress,intense determination or desperation.sress,intense determination or desperation.

 Pain in thePain in the temporalistemporalis muscle may be due tomuscle may be due to
premature contact & too large increase inpremature contact & too large increase in
vertical dimension causes overload ofvertical dimension causes overload of
temporalis, masseter and medial pterygoidtemporalis, masseter and medial pterygoid
muscles.muscles.
 Soreness in relation to medial pterygoid & lateralSoreness in relation to medial pterygoid & lateral
pterygoid may be due to occlusal disharmony,pterygoid may be due to occlusal disharmony,
excessive gum chewing & bruxism.excessive gum chewing & bruxism.

References from journalsReferences from journals
 Passive control in mandibular rest positionPassive control in mandibular rest position
 J.P.D:1969:22;31-36J.P.D:1969:22;31-36
 The results suggests that the mandibular rest position isThe results suggests that the mandibular rest position is
largely governed by equilibration of muscle elasticlargely governed by equilibration of muscle elastic
forces when the subject is fully relaxed.forces when the subject is fully relaxed.
 The influence of other factors, such as gravity, bodyThe influence of other factors, such as gravity, body
posture,intra oral pressure & environment inducedposture,intra oral pressure & environment induced
muscle activity may affect the equilibrium position ofmuscle activity may affect the equilibrium position of
the mandible at any time in an individual.the mandible at any time in an individual.

Continuous observations ofContinuous observations of
mandibular positions by telemetrymandibular positions by telemetry..
J.P.D:1972:28;485 - 490J.P.D:1972:28;485 - 490
 The results of this study indicated that the mandibularThe results of this study indicated that the mandibular
positions were quite stable when the subject was seatedpositions were quite stable when the subject was seated
in an upright position.in an upright position.
 Mandibular vibrations were observed at all times inMandibular vibrations were observed at all times in
every mandibular position even at rest.every mandibular position even at rest.
 Rest position of mandible clinically measured hasRest position of mandible clinically measured has
revealed that there are continuously changingrevealed that there are continuously changing
mandibular positions. For this reason it is essential tomandibular positions. For this reason it is essential to
record mandibular positions continuously.record mandibular positions continuously.

Mandibular position sense in manMandibular position sense in man
Frontiers of oral physiolgy:1983:4:80-101Frontiers of oral physiolgy:1983:4:80-101
 In this study the mandibular position sense wasIn this study the mandibular position sense was
studied before & after injection of 1% Xylocainestudied before & after injection of 1% Xylocaine
solution into the unilateral joint capsule.solution into the unilateral joint capsule.
 The results indicated that the mean range ofThe results indicated that the mean range of
mandibular position before anesthesia wasmandibular position before anesthesia was
3.2mm & increased upto 9.4mm after anesthesia.3.2mm & increased upto 9.4mm after anesthesia.
 The results suggest that the position sense ofThe results suggest that the position sense of
mandible is mainly observed by the jointmandible is mainly observed by the joint
receptors but not by the muscle receptors.receptors but not by the muscle receptors.

ConclusionConclusion
 Since there is no effective way to achieve maintainableSince there is no effective way to achieve maintainable
oral health without harmony of all the parts of theoral health without harmony of all the parts of the
masticatory system ,what effects one part of the systemmasticatory system ,what effects one part of the system
will eventually affect the other parts .will eventually affect the other parts .
 So as prosthodontists we should understand theSo as prosthodontists we should understand the
interrelated form and functions of theinterrelated form and functions of the
teeth,muscles,joints,bones & ligaments before we treatteeth,muscles,joints,bones & ligaments before we treat
the stomatognathic system, so that the masticatorythe stomatognathic system, so that the masticatory
ability is improved rather than worsened by dentalability is improved rather than worsened by dental
treatment.treatment.

BibliographyBibliography
1.1. Text book of anatomy & physiology-TortoraText book of anatomy & physiology-Tortora
& Grabowski.& Grabowski.
2.2. Essentials of Medical physiology-Essentials of Medical physiology-
ShembhulingamShembhulingam
3.3. Frontiers of Oral physiology-Frontiers of Oral physiology- KargerKarger
4.4. Essentials of Oral physiology-Essentials of Oral physiology- BradleyBradley
5.5. Review of medical physiology-Review of medical physiology- GanongGanong
6.6. Myofascial pain and trigger points manual-Myofascial pain and trigger points manual-
Travel and Simon’sTravel and Simon’s
7.7. Oral cells & tissues-Oral cells & tissues- P.R.GrantP.R.Grant
8.8. Management of TMD & occlusion-Management of TMD & occlusion-
Jeffrey.P.okesonJeffrey.P.okeson
9.9. Evaluation ,diagnosis & treatment of occlusalEvaluation ,diagnosis & treatment of occlusal
problems-problems- Peter.E.DawsonPeter.E.Dawsonwww.indiandentalacademy.com

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