Physiology of stomatognathic system

PHYSIOLOGY OFPHYSIOLOGY OF
STOMATOGNATHICSTOMATOGNATHIC
SYSTEMSYSTEM
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INTRODUCTION OFINTRODUCTION OF
PHYSIOLOGY OF STOMATOGNATHIC SYSTEMPHYSIOLOGY OF STOMATOGNATHIC SYSTEM
STOMA - MOUTHSTOMA - MOUTH
GNATHIA - JAWSGNATHIA - JAWS
THE STRUCTURES OF THE MOUTH AND JAWS,THE STRUCTURES OF THE MOUTH AND JAWS,
CONSIDERED COLLECTIVELY AS THEY SUBSERVECONSIDERED COLLECTIVELY AS THEY SUBSERVE
THE FUNCTIONS OF MASTICATION, DEGLUTITION,THE FUNCTIONS OF MASTICATION, DEGLUTITION,
RESPIRATION AND SPEECH IS CALLED ASRESPIRATION AND SPEECH IS CALLED AS
STOMATOGNATHIC SYSTEMSTOMATOGNATHIC SYSTEM
(( DORLAND MEDICAL DICTIONARYDORLAND MEDICAL DICTIONARY ))

CONTENTSCONTENTS
OSTEOLOGY
FUNCTIONAL OSTEOLOGYFUNCTIONAL OSTEOLOGY
MYOLOGYMYOLOGY
MUSCLES OF FACE , TONGUE,MUSCLES OF FACE , TONGUE,
MASTICATIONMASTICATION
TEMPOROMANDIBULAR JOINTTEMPOROMANDIBULAR JOINT
ANATOMY OF TMJANATOMY OF TMJ
MOVEMENTS OF MANDIBLEMOVEMENTS OF MANDIBLE
FUNCTIONS OF STOMATOGNATHICFUNCTIONS OF STOMATOGNATHIC
SYSTEMSYSTEMwww.indiandentalacademy.comwww.indiandentalacademy.com

BONEBONE
INTRODUCTIONINTRODUCTION
WHAT IS BONEWHAT IS BONE
FUNCTIONSFUNCTIONS
CLASSIFICATION OF BONECLASSIFICATION OF BONE
BONE MORPHOLOGYBONE MORPHOLOGY

MICROSCOPIC STRUCTUREMICROSCOPIC STRUCTURE
PHASES OF BONEPHASES OF BONE
BONE MINERALBONE MINERAL
MECHANICAL PROPERTIES OF BONEMECHANICAL PROPERTIES OF BONE

INTRODUCTION OF BONEINTRODUCTION OF BONE

WHAT IS BONE ?WHAT IS BONE ?
SPECIALISED FORM OF CONNECTIVE TISSUESPECIALISED FORM OF CONNECTIVE TISSUE
EXTRACELLULAR MATRIX –EXTRACELLULAR MATRIX –
COLLAGEN , PROTEINS,COLLAGEN , PROTEINS,
PROTEOGLYCANS , MINERALPROTEOGLYCANS , MINERAL

FUNCTIONS OF BONEFUNCTIONS OF BONE
PROTECTIONPROTECTION
SITE OF MUSCLE ORIGIN AND INSERTIONSITE OF MUSCLE ORIGIN AND INSERTION
RIGIDITYRIGIDITY
HAEMOPOIESISHAEMOPOIESIS
LABILE MINERAL POOLLABILE MINERAL POOL

BONE MORPHOLOGYBONE MORPHOLOGY
CATEGORISATION:CATEGORISATION:
TUBULARTUBULAR -- FEMUR-- FEMUR
CUBOIDALCUBOIDAL -- CARPUS-- CARPUS
FLATFLAT -- FRONTAL BONE-- FRONTAL BONE
IRREGULARIRREGULAR -- VERTEBRAE-- VERTEBRAE

ACCORDING TO DEVELOPMENTALACCORDING TO DEVELOPMENTAL ORIGINORIGIN
ENDOCHONDRAL BONEENDOCHONDRAL BONE
INTRAMEMBRANOUS BONEINTRAMEMBRANOUS BONE

ENDOCHONDRAL BONE FORMATIONENDOCHONDRAL BONE FORMATION
 BONE FORMATION IS PRECEDED BY FORMATIONBONE FORMATION IS PRECEDED BY FORMATION
OF CARTILAGENOUS MODEL – REPLACED BY BONEOF CARTILAGENOUS MODEL – REPLACED BY BONE
 MESENCHYMAL CELLS - CONDENSED –MESENCHYMAL CELLS - CONDENSED –
CHONDROBLASTS -- HYALINE CARTILAGECHONDROBLASTS -- HYALINE CARTILAGE
((PERICHONDRIUM, VASCULAR AND OSTEOGENIC CELLS)PERICHONDRIUM, VASCULAR AND OSTEOGENIC CELLS)
– INTERCELLULAR – CALCIFIED BY ENZYME ALKALINEINTERCELLULAR – CALCIFIED BY ENZYME ALKALINE
PHOSPHATASE SECRETED BY CARTILAGE CELLSPHOSPHATASE SECRETED BY CARTILAGE CELLS
– EMPTY SPACES ---PRIMARY AREOLAE ---SECONDARYEMPTY SPACES ---PRIMARY AREOLAE ---SECONDARY
AREOLAEAREOLAE
– OSTEOGENIC CELLS – OSTEOBLASTS – OSTEOID –OSTEOGENIC CELLS – OSTEOBLASTS – OSTEOID –
CALCIFIED - LAMELLA OF BONECALCIFIED - LAMELLA OF BONE

INTRAMEMBRANOUS BONEINTRAMEMBRANOUS BONE
 BONE LAID DOWN DIRECTLY IN FIBROUS MEMBRANEBONE LAID DOWN DIRECTLY IN FIBROUS MEMBRANE
 MESENCHYMAL CELLS – BUNDLES OF COLLAGEN FIBRESMESENCHYMAL CELLS – BUNDLES OF COLLAGEN FIBRES
 ALSO ENLARGE – BASOPHILIC CYTOPLASM –ALSO ENLARGE – BASOPHILIC CYTOPLASM –
OSTEOBLASTS – GELATINOUS MATRIX(OSTEOID) –BONEOSTEOBLASTS – GELATINOUS MATRIX(OSTEOID) –BONE
LAMELLAE – OSTEOBLASTS MOVE AWAY – OSTEOID –LAMELLAE – OSTEOBLASTS MOVE AWAY – OSTEOID –
CALCIFIED – BONECALCIFIED – BONE
 OSTEOBLASTS TRAPPED BETWEEN TWO LAMELLAE k/aOSTEOBLASTS TRAPPED BETWEEN TWO LAMELLAE k/a
OSTEOCYTES.OSTEOCYTES.

CLASSIFICATION OF BONE TISSUECLASSIFICATION OF BONE TISSUE
 WOVEN BONEWOVEN BONE
 LAMELLAR BONELAMELLAR BONE
 COMPOSITE BONECOMPOSITE BONE
 BUNDLE BONEBUNDLE BONE

WOVEN BONEWOVEN BONE
 WEAK, DISORGANIZED, POORLY MINERALIZEDWEAK, DISORGANIZED, POORLY MINERALIZED
 SERVES WOUND HEALING BY :SERVES WOUND HEALING BY :
 RAPIDLY FILLING OSSEOUS DEFECTSRAPIDLY FILLING OSSEOUS DEFECTS
 INITIAL CONTINUITY FOR FRACTURES AND OSTEOTOMYINITIAL CONTINUITY FOR FRACTURES AND OSTEOTOMY
SEGMENTSSEGMENTS
 STRENGTHENING BONE WEAKENED BY SURGERY ORSTRENGTHENING BONE WEAKENED BY SURGERY OR
TRAUMATRAUMA
 FIRST FORMED BONE TO ORTHODONTICFIRST FORMED BONE TO ORTHODONTIC
LOADINGLOADING

 NOT FOUND IN ADULT SKELETONNOT FOUND IN ADULT SKELETON
 FUNCTIONAL LIMITATIONS :FUNCTIONAL LIMITATIONS :
IMP. ASPECTS OF ORTHODONTIC RETENTIONIMP. ASPECTS OF ORTHODONTIC RETENTION
HEALING PERIOD FOLL. ORTHOGNATHC SURGERYHEALING PERIOD FOLL. ORTHOGNATHC SURGERY

LAMELLAR BONELAMELLAR BONE
 STRONG,HIGHLY ORGANISED, WELL MINERALIZEDSTRONG,HIGHLY ORGANISED, WELL MINERALIZED
 99% ADULT SKELETON99% ADULT SKELETON
 STRENGTH OF BONE DIRECTLY RELATED TO MINERALSTRENGTH OF BONE DIRECTLY RELATED TO MINERAL
COMPONENTCOMPONENT
WOVEN BONE < NEW LAMELLAR BONE < MATURE LAMELLARWOVEN BONE < NEW LAMELLAR BONE < MATURE LAMELLAR
BONEBONE

COMPOSITE BONECOMPOSITE BONE
 LAMELLAR BONE WITH IN WOVEN BONE LATTICELAMELLAR BONE WITH IN WOVEN BONE LATTICE
 PRODUCES STRONG BONEPRODUCES STRONG BONE
 PRIMARY OSTEONSPRIMARY OSTEONS
 SECONDARY OSTEONSSECONDARY OSTEONS

BUNDLE BONEBUNDLE BONE
 FUNCTIONAL ADAPTATIONFUNCTIONAL ADAPTATION
 ATTACHMENTS OF TENDONS , LIGAMENTSATTACHMENTS OF TENDONS , LIGAMENTS
 SHARPEY’S FIBRESSHARPEY’S FIBRES

MICROSCOPIC STRUCTUREMICROSCOPIC STRUCTURE
CANCELLOUS BONE (SPONGY BONE) ----CANCELLOUS BONE (SPONGY BONE) ----
TRABECULAE ----OSTEOCYTES ----TRABECULAE ----OSTEOCYTES ----
LACUNAELACUNAE
CORTICAL BONE ( COMPACT BONE) –CORTICAL BONE ( COMPACT BONE) –
BASIC STRUCTURE – HAVERSIAN SYSTEMBASIC STRUCTURE – HAVERSIAN SYSTEM

HAVERSIAN
SYSTEM
CENTRAL VASCULARCENTRAL VASCULAR
CANALCANAL
8 -10 CONCENTRIC8 -10 CONCENTRIC
LAMELLAELAMELLAE
CEMENT LINESCEMENT LINES
VOLKMAN’S CANALVOLKMAN’S CANAL

PHASES OF BONEPHASES OF BONE
OSSEOUS MATRIX ---- ORGANIC,INORGANICOSSEOUS MATRIX ---- ORGANIC,INORGANIC
COMPONENTSCOMPONENTS
CELLULAR COMPONENTS ----CELLULAR COMPONENTS ----
OSTEOBLASTS,OSTEOCYTES,OSTEOCLASTSOSTEOBLASTS,OSTEOCYTES,OSTEOCLASTS

BONE MINERAL
RESEMBLES PRECIPITATED HYDROXYAPATITES.RESEMBLES PRECIPITATED HYDROXYAPATITES.
DISTINCTIVE FEATURES OF BONE APATITE :DISTINCTIVE FEATURES OF BONE APATITE :
SMALL CRYSTAL SIZESMALL CRYSTAL SIZE
LACK OF CHEMICAL PERFECTIONLACK OF CHEMICAL PERFECTION
INTERNAL CHEMICAL DISORDERINTERNAL CHEMICAL DISORDER

MECHANICAL PROPERTIES OF
BONE
TENSILE STRENGTHTENSILE STRENGTH::
DEPENDS ON ORIENTATION AND NUMBER OFDEPENDS ON ORIENTATION AND NUMBER OF
COMPONENT COLLAGEN FIBRES.COMPONENT COLLAGEN FIBRES.
SUPERIOR WHEN COLLAGEN FIBRES ARE PARALLEL TOSUPERIOR WHEN COLLAGEN FIBRES ARE PARALLEL TO
LONG AXIS OF TENSION.LONG AXIS OF TENSION.
HAVERSIAN SYSTEMS WITH HIGH LEVEL OFHAVERSIAN SYSTEMS WITH HIGH LEVEL OF
CALCIFICATION ARE STIFFER.CALCIFICATION ARE STIFFER.

COMPRESSIVE PROPERTIES
DEPENDS ON ARRANGEMENT OF COMPONENT COLLAGENDEPENDS ON ARRANGEMENT OF COMPONENT COLLAGEN
FIBRESFIBRES
CIRCUMFERENTIAL COLLAGENOUS FIBRES -------CIRCUMFERENTIAL COLLAGENOUS FIBRES -------
SUPERIOR COMPRESSIVE STRENGTH,SUPERIOR COMPRESSIVE STRENGTH,
INFERIOR TENSILE PROPERTIESINFERIOR TENSILE PROPERTIES
LONGITUDINAL COLLAGEN FIBRES --------LONGITUDINAL COLLAGEN FIBRES --------
SUPERIOR TENSILE ,SUPERIOR TENSILE ,
INFERIOR COMPRESSIVE PROPERTIESINFERIOR COMPRESSIVE PROPERTIES

FUNCTIONAL OSTEOLOGYFUNCTIONAL OSTEOLOGY

TRAJECTORIAL THEORY OF BONE
FORMATION
MEYER (1867) , CULMANNMEYER (1867) , CULMANN
TRAJECTORIAL THEORY OF BONE
FORMATION
BENNINGHOFFBENNINGHOFF ----
(STRESS TRAJECTORIES)(STRESS TRAJECTORIES)
JULIUS WOLF (1870)
(LAW OF ORTHOGONALITY)
ROUX
(LAW OF TRANSFORMATION OF BONE)(LAW OF TRANSFORMATION OF BONE)

 VANDERKLAUVANDERKLAU
(FUNCTIONAL CRANIAL COMPONENT)(FUNCTIONAL CRANIAL COMPONENT)
 MELVIN MOSSMELVIN MOSS
(FUNCTIONAL MATRIX HYPOTHESIS)(FUNCTIONAL MATRIX HYPOTHESIS)

MECHANISMS OF BONE GROWTHMECHANISMS OF BONE GROWTH

BONE DEPOSITION AND RESORPTIONBONE DEPOSITION AND RESORPTION
BONE DEPOSITIONBONE DEPOSITION
BONE RESORPTIONBONE RESORPTION
BONE REMODELINGBONE REMODELING

MODELING AND REMODELINGMODELING AND REMODELING
SKELETAL ADAPTATION :SKELETAL ADAPTATION :
 ALTERATION IN MASSALTERATION IN MASS
 GEOMETRIC DISTRIBUTIONGEOMETRIC DISTRIBUTION
 MATRIX ORGANISATIONMATRIX ORGANISATION
 COLLAGEN ORIENTATION OF LAMELLAECOLLAGEN ORIENTATION OF LAMELLAE

BONEBONE MODELINGMODELING
INDEPENDENT SITES , CHANGE THE
FORM OF BONE
SPECIFIC, REPLACES PREVIOUSLY
EXISTING BONE

INTERNAL REMODELING VIA AXIALLY ORIENTEDINTERNAL REMODELING VIA AXIALLY ORIENTED
CUTTING /FILLING CONESCUTTING /FILLING CONES

MODELING CHANGESMODELING CHANGES -- CEPHALOMETRIC TRACINGS-- CEPHALOMETRIC TRACINGS
REMODELING CHANGESREMODELING CHANGES -- MICROSCOPIC LEVEL-- MICROSCOPIC LEVEL
TRUE REMODELINGTRUE REMODELING -- NOT IMAGED ON CLINICAL-- NOT IMAGED ON CLINICAL
RADIOGRAPHSRADIOGRAPHS
CONSTANT REMODELING –- COUPLING FACTORSCONSTANT REMODELING –- COUPLING FACTORS
( INTERNAL TURNOVER)( INTERNAL TURNOVER)

ORTHODONTIC BONE MODELINGORTHODONTIC BONE MODELING

 REGIONAL ACCELERATORY PHENOMENONREGIONAL ACCELERATORY PHENOMENON
 CLINICAL IMPORTANCE :CLINICAL IMPORTANCE :
 ORTHOPEDICALLY POSITION MAXILLAORTHOPEDICALLY POSITION MAXILLA
 RAPID ORTHODONTIC ALIGNMENT OF TEETH FOLL.RAPID ORTHODONTIC ALIGNMENT OF TEETH FOLL.
ORTHOGNATHIC SURGERYORTHOGNATHIC SURGERY

CONTROLLED BY :CONTROLLED BY :
METABOLIC AND MECHANICAL SIGNALSMETABOLIC AND MECHANICAL SIGNALS
 MODELING :MODELING : CONTROLLED BY :CONTROLLED BY :
 FUNCTIONAL APPLIED LOADSFUNCTIONAL APPLIED LOADS
 HORMONESHORMONES
 METABOLIC AGENTSMETABOLIC AGENTS
 PARACRINE AND AUTOCRINE MECHANISMSPARACRINE AND AUTOCRINE MECHANISMS
( LOCAL GROWTH FACTORS , PROSTAGLANDINS )( LOCAL GROWTH FACTORS , PROSTAGLANDINS )

 REMODELING :REMODELING :
METABOLIC DISORDERSMETABOLIC DISORDERS
( PARATHYROID HORMONES AND ESTROGENS )( PARATHYROID HORMONES AND ESTROGENS )

BOIMECHANICSBOIMECHANICS
 GRAVITYGRAVITY
 MECHANICAL LOADINGMECHANICAL LOADING

 FROST’S MECHANOSTAT THEORYFROST’S MECHANOSTAT THEORY
 MARTIN AND BURRMARTIN AND BURR
 DISUSE ATROPHY -- < 200DISUSE ATROPHY -- < 200 µEµE

PHYSIOLOGICAL LOADINGPHYSIOLOGICAL LOADING -- 200 - 2500µE-- 200 - 2500µE

HYPERTROPHIC INCREASE -- 2500 - 4000HYPERTROPHIC INCREASE -- 2500 - 4000µEµE

PATHOLOGIC OVERLOAD -- > 4000PATHOLOGIC OVERLOAD -- > 4000µEµE

 CLINICAL REFERENCECLINICAL REFERENCE
BIOMECHANICAL RESPONSES TO APPLIEDBIOMECHANICAL RESPONSES TO APPLIED
LOADSLOADS

IMP. OBJECTIVES OF ORTHODONTIC TREATMENTIMP. OBJECTIVES OF ORTHODONTIC TREATMENT
 AVOIDING OCCLUSAL PREMATURITIESAVOIDING OCCLUSAL PREMATURITIES
 GUARDING EXCESSIVE TOOTH MOBILITYGUARDING EXCESSIVE TOOTH MOBILITY
 OPTIMAL DISTRIBUTION OF OCCLUSAL LOADSOPTIMAL DISTRIBUTION OF OCCLUSAL LOADS

DISTRACTION OSTEOGENESISDISTRACTION OSTEOGENESIS
 BONES CAN BE INDUCED TO GROW ATBONES CAN BE INDUCED TO GROW AT
SURGICALLY – CREATED SITES.SURGICALLY – CREATED SITES.
 A PROCESS OF NEW BONE FORMATION BETWEENA PROCESS OF NEW BONE FORMATION BETWEEN
SURFACES OF BONE SEGMENTS SEPARATED BYSURFACES OF BONE SEGMENTS SEPARATED BY
INCREMENTAL TRACTION (COPE -- 1999)INCREMENTAL TRACTION (COPE -- 1999)

ALIZAROVALIZAROV
(1950)(1950)

GROWTH OF MAXILLA :GROWTH OF MAXILLA :
 AT SUTURESAT SUTURES
 DIRECT REMODELINGDIRECT REMODELING
 TRANSLATED DOWNWARDS AND FORWARDSTRANSLATED DOWNWARDS AND FORWARDS
GROWTH OF MANDIBLE :GROWTH OF MANDIBLE :
 ENDOCHONDRAL PROLIFERATION AT THE CONDYLEENDOCHONDRAL PROLIFERATION AT THE CONDYLE
 APPOSTION AND RESORPTION OF BONEAPPOSTION AND RESORPTION OF BONE

Steps involved :Steps involved :
 Corticotomy/OsteotomyCorticotomy/Osteotomy
 Latency periodLatency period
 Distraction phaseDistraction phase
 Consolidation phaseConsolidation phase

TENSION STRESS EFFECTTENSION STRESS EFFECT

CURRENT SCOPECURRENT SCOPE ::
 Correction of Maxillo-Mandibular deformitiesCorrection of Maxillo-Mandibular deformities
Maxillary lengtheningMaxillary lengthening
Mandibular lengtheningMandibular lengthening
Maxillary and Mandibular wideningMaxillary and Mandibular widening
Lengthening of the Hard palateLengthening of the Hard palate
Distraction in other cranio-facial areasDistraction in other cranio-facial areas

 Alveolar ridge augmentationAlveolar ridge augmentation
 Transport disc and TransformationTransport disc and Transformation
osteogenesis.osteogenesis.
 Dental Distraction.Dental Distraction.

TISSUE CHANGES FOLLOWING DOTISSUE CHANGES FOLLOWING DO
HISTOLOGIC CHANGES :HISTOLOGIC CHANGES :
 During latency phase – formation of aDuring latency phase – formation of a
fibrous bridge.fibrous bridge.
 During distraction phase – distinct zonesDuring distraction phase – distinct zones
seenseen

FACTORS AFFECTING DOFACTORS AFFECTING DO
Biologic :Biologic :
 AGEAGE
 SITE OF SURGERYSITE OF SURGERY
 LATENCY PERIODLATENCY PERIOD
 RATE AND RHYTHMRATE AND RHYTHM

BIOMECHANICAL FACTORS :BIOMECHANICAL FACTORS :
 Planning the distraction vectorPlanning the distraction vector
 Device fixityDevice fixity
 Need for ‘ Bone moulding’Need for ‘ Bone moulding’

Mandibular DistractionMandibular Distraction
INDICATIONS:INDICATIONS:
Hemifacial MicrosomiaHemifacial Microsomia
Treacher Collin Syndrome etc.Treacher Collin Syndrome etc.
TMJ ankylosis and condylar fracturesTMJ ankylosis and condylar fractures
Transverse deficiency of the mandibleTransverse deficiency of the mandible

BIOMECHANICAL EFFECTS OF DISTRACTONBIOMECHANICAL EFFECTS OF DISTRACTON
VECTORVECTOR

THE SKULLTHE SKULL
INTRODUCTIONINTRODUCTION

SKULLSKULL
CALVARIA
(BRAIN BOX)
FACIAL SKELETON

 BONES OF THE SKULL : 22 BONESBONES OF THE SKULL : 22 BONES
CALVARIA OR BRAIN CASE: 8 bonesCALVARIA OR BRAIN CASE: 8 bones
PAIREDPAIRED UNPAIREDUNPAIRED
PARIETALPARIETAL FRONTALFRONTAL
TEMPORALTEMPORAL OCCIPITALOCCIPITAL
SPHENOIDSPHENOID
ETHMOIDETHMOID

FACIAL SKELETON : 14 bonesFACIAL SKELETON : 14 bones
PAIREDPAIRED UNPAIREDUNPAIRED
MAXILLAMAXILLA MANDIBLEMANDIBLE
ZYGOMATICZYGOMATIC VOMERVOMER
NASALNASAL
LACRIMALLACRIMAL
PALATINEPALATINE
INFERIOR NASAL CONCHAINFERIOR NASAL CONCHA

MANDIBLE
LARGEST,STRONGEST BONELARGEST,STRONGEST BONE
FIRST PHARYNGEAL ARCHFIRST PHARYNGEAL ARCH
HORSE SHOE SHAPED BODYHORSE SHOE SHAPED BODY
PAIR OF RAMIPAIR OF RAMI

BODY OF MANDIBLEBODY OF MANDIBLE
SURFACES:SURFACES:
OUTER SURFACEOUTER SURFACE
INNER SURFACEINNER SURFACE
BORDERS:BORDERS:
UPPER BORDERUPPER BORDER
LOWER BORDERLOWER BORDER

OSSIFICATIONOSSIFICATION
Greater part ossifies in membraneGreater part ossifies in membrane
Parts ossifying in cartilage –Parts ossifying in cartilage –
incisive, coronoid, condyloid, upper halfincisive, coronoid, condyloid, upper half
of ramus.of ramus.
Each half ossifies from only one centre – 6Each half ossifies from only one centre – 6thth
week of intra uterine life -- in mesenchymalweek of intra uterine life -- in mesenchymal
sheath of meckel’s cartilage – mentalsheath of meckel’s cartilage – mental foramen.foramen.
Symphysis mentiSymphysis menti

AGE CHANGES IN THE MANDIBLEAGE CHANGES IN THE MANDIBLE
IN INFANTS AND CHILDREN:IN INFANTS AND CHILDREN:
Two halves fuse -- first year of lifeTwo halves fuse -- first year of life
At birth – mental foramen opens below the socketsAt birth – mental foramen opens below the sockets
Angle is obtuse -- 140 degrees or moreAngle is obtuse -- 140 degrees or more

IN ADULTSIN ADULTS
Mental foramen opens mid-wayMental foramen opens mid-way
Angle reduces – 110 or 120 degreesAngle reduces – 110 or 120 degrees

IN OLD AGEIN OLD AGE
Alveolar bone resorbed.Alveolar bone resorbed.
Mental foramen and mandibular canal – close toMental foramen and mandibular canal – close to
alveolar border.alveolar border.
Angle again – obtuse– 140 degrees.Angle again – obtuse– 140 degrees.

MAXILLAMAXILLA
---- second largest bone of the face, first beingsecond largest bone of the face, first being
mandiblemandible
FEATURES:FEATURES:
BODY.BODY.
FOUR PROCESSES:FOUR PROCESSES:
Frontal, zygomatic,Frontal, zygomatic,
alveolar, palatine.alveolar, palatine.

BODY:BODY:
pyramidal in shape , base directed medially,pyramidal in shape , base directed medially,
apexapex laterally.laterally.
four surfacesfour surfaces
encloses maxillary sinus.encloses maxillary sinus.

OSSIFICATIONOSSIFICATION
OSSIFIES IN MEMBRANEOSSIFIES IN MEMBRANE
FROM THREE CENTRES :FROM THREE CENTRES :
ONE FOR MAXILLA PROPERONE FOR MAXILLA PROPER
TWO FOR OS INCISIVUM OR PREMAXILLATWO FOR OS INCISIVUM OR PREMAXILLA

MAXILLA PROPERMAXILLA PROPER
CENTRE:CENTRE:
ABOVE CANINE FOSSA,ABOVE CANINE FOSSA,
66THTH
WEEK OF INTRAUTERINE LIFEWEEK OF INTRAUTERINE LIFE

PREMAXILLAPREMAXILLA
MAIN CENTRE:MAIN CENTRE:
ABOVE INCISIVE FOSSAABOVE INCISIVE FOSSA
77THTH
WEEK OF INTRAUTERINE LIFEWEEK OF INTRAUTERINE LIFE
SECOND CENTRE (PARASEPTAL / PREVOMERINE):SECOND CENTRE (PARASEPTAL / PREVOMERINE):
VENTRAL MARGIN OF NASAL SEPTUMVENTRAL MARGIN OF NASAL SEPTUM
1010THTH
WEEKWEEK
FUSES WITH PALATAL PROCESSFUSES WITH PALATAL PROCESS

AGE CHANGESAGE CHANGES
AT BIRTH:
TRANSVERSE AND AP DIAMETER MORE THANTRANSVERSE AND AP DIAMETER MORE THAN
VERTICAL.VERTICAL.
FRONTAL PROCESSES WELL MARKED.FRONTAL PROCESSES WELL MARKED.
BODY LITTLE MORE THAN ALVEOLAR PROCESSESBODY LITTLE MORE THAN ALVEOLAR PROCESSES
TOOTH SOCKETS REACHING FLOOR OF ORBITTOOTH SOCKETS REACHING FLOOR OF ORBIT
MAXILLARY SINUS MERE FURROW ON LATERAL WALLMAXILLARY SINUS MERE FURROW ON LATERAL WALL
OF NOSE.OF NOSE.

ADULT:
VERTICAL DIAMETER GREATESTVERTICAL DIAMETER GREATEST
OLD:
REVERTS TO INFANTILE CONDITION
HEIGHT REDUCEDHEIGHT REDUCED

 Sutures of maxillaSutures of maxilla
– Frontomaxillary sutureFrontomaxillary suture
– LacrimomaxillaryLacrimomaxillary
– ZygomaticomaxillaryZygomaticomaxillary
– EthmoidomaxillaryEthmoidomaxillary
– PalatomaxillaryPalatomaxillary
– NasomaxillaryNasomaxillary
– SphenomaxillarySphenomaxillary
– IntermaxillaryIntermaxillary

MYOLOGYMYOLOGY
STUDY OF MUSCLES,MUSCULAR SYSTEMSTUDY OF MUSCLES,MUSCULAR SYSTEM
AND THEIR FUNCTIONS AND DISORDERSAND THEIR FUNCTIONS AND DISORDERS..
MUSCLE:MUSCLE:
Physical properties: kinetic activityPhysical properties: kinetic activity
1: Elasticity.1: Elasticity.
2: Contractility.2: Contractility.

Elasticity:Elasticity:
a) length.a) length.
b) cross- section.b) cross- section.
c) force exerted.c) force exerted.
d) constant coefficient.d) constant coefficient.
RATIO IN UNIAXIAL CASE :RATIO IN UNIAXIAL CASE :
FFΔ = AELΔ = AEL

Hooke’s law :Hooke’s law :
Muscle returns to exact original shape after beingMuscle returns to exact original shape after being
stretched.stretched.
The linear elastic range is dependent upon theThe linear elastic range is dependent upon the
nature of material involved.nature of material involved.
Valid and linear only at initial stage.Valid and linear only at initial stage.

CONTRACTILITY:CONTRACTILITY:
The ability of a muscle to shorten it’s length underThe ability of a muscle to shorten it’s length under
innervational impulseinnervational impulse

SHERRINGTONSHERRINGTON :: ALL OR NONE LAWALL OR NONE LAW
The intensity of contraction of any fibre isThe intensity of contraction of any fibre is
independent of the strength of the excitingindependent of the strength of the exciting
stimulus, provided the stimulus is adequate.stimulus, provided the stimulus is adequate.
The strength of muscle contraction depends on :The strength of muscle contraction depends on :
The frequency of stimuli.The frequency of stimuli.
No. of fibres involved.No. of fibres involved.
Applies only when muscle is in physiologic reactingApplies only when muscle is in physiologic reacting
statestate

ISOMETRIC CONTRACTION :ISOMETRIC CONTRACTION :
Occurs when a muscle is simply resisting anOccurs when a muscle is simply resisting an
external force without any actual shortening.external force without any actual shortening.
ISOTONIC CONTRACTION :ISOTONIC CONTRACTION :
there is actual shortening. Eg.flexing thethere is actual shortening. Eg.flexing the
biceps.biceps.

PRINCIPLES OF MUSCLEPRINCIPLES OF MUSCLE
PHYSIOLOGYPHYSIOLOGY
Visualisation by Electromyogram.Visualisation by Electromyogram.
EINTHOVENEINTHOVEN (1918).(1918).
(Action current)(Action current)
ADVANTAGE :ADVANTAGE :
Relatively accurate picture of muscle activityRelatively accurate picture of muscle activity
under diverse functional conditions.under diverse functional conditions.

 Muscle Tonus:Muscle Tonus:
is a state of slight constant tension .is a state of slight constant tension .
Serves to obviate the muscle.Serves to obviate the muscle.
Basis of reflex posture.Basis of reflex posture.
Maintenance of various positionsMaintenance of various positions..
 Resting Length:Resting Length:
Permits maintenance of postural relations andPermits maintenance of postural relations and
dynamic equilibrium -- contraction of minimaldynamic equilibrium -- contraction of minimal
no. of fibres.no. of fibres.

 Stretch or Myotactic reflexes:Stretch or Myotactic reflexes:
The reflex contraction of a healthy muscle whichThe reflex contraction of a healthy muscle which
results from a pull on its tendon.results from a pull on its tendon.
(Achilles Tendon Reflex)(Achilles Tendon Reflex)
 Reciprocal Innervation and Inhibition:Reciprocal Innervation and Inhibition:
Given by Sherrington.Given by Sherrington.
Brought about by excitation of its antagonistBrought about by excitation of its antagonist..

THE FACETHE FACE
MUSCLES OF THE FACEMUSCLES OF THE FACE

 FACIAL MUSCLESFACIAL MUSCLES
SUBCUTANEOUS MUSCLESSUBCUTANEOUS MUSCLES
EMBRYOLOGICALLY:EMBRYOLOGICALLY:
Mesoderm of second branchial archMesoderm of second branchial arch
supplied by facial nervesupplied by facial nerve
MORPHOLOGICALLY:MORPHOLOGICALLY:
remnants of panniculus carnosusremnants of panniculus carnosus

 TOPOGRAPHICALLYTOPOGRAPHICALLY::
SIX HEADS;SIX HEADS;
MUSCLES OF THE SCALPMUSCLES OF THE SCALP
MUSCLES OF AURICLEMUSCLES OF AURICLE
MUSCLES OF EYELIDSMUSCLES OF EYELIDS
MUSCLES OF THE NOSEMUSCLES OF THE NOSE
MUSCLES AROUND MOUTHMUSCLES AROUND MOUTH
MUSCLES OF THE NECKMUSCLES OF THE NECK

ORBICULARIS ORISORBICULARIS ORIS
Composed of eight segments, eachComposed of eight segments, each
segment resembles a fan wth its stem atsegment resembles a fan wth its stem at
the modiolus.the modiolus.
Each fan is open in peripheral segmentsEach fan is open in peripheral segments
and closed in marginal segments.and closed in marginal segments.
ORIGIN AND INSERTIONORIGIN AND INSERTION ::
Intrinsic part :Intrinsic part :
superior incisivus from maxilla and inferiorsuperior incisivus from maxilla and inferior
from mandible –inserting into the angle offrom mandible –inserting into the angle of
mouth.mouth.

 Extrinsic part :Extrinsic part :
– middle strata from buccinator and superficialmiddle strata from buccinator and superficial
from lips and inserts into lips and angle offrom lips and inserts into lips and angle of
mouth.mouth.
ACTIONS :ACTIONS :
Closing the mouth.Closing the mouth.
whistling.whistling.

BUCCINATORBUCCINATOR
Thin , quadrilateral muscle between maxillaThin , quadrilateral muscle between maxilla
and mandible.and mandible.

ORIGIN AND INSERTION :ORIGIN AND INSERTION :
Upper fibres – opposite maxillary molars –Upper fibres – opposite maxillary molars –
insert in upper lip.insert in upper lip.
Middle fibres – pterygomandibular raphe –Middle fibres – pterygomandibular raphe –
decussate.decussate.

 Lower fibres -- opposite mandibular molarsLower fibres -- opposite mandibular molars
– insert in lower lip.– insert in lower lip.
ACTIONS :ACTIONS :
Compresses the cheeks against teeth,Compresses the cheeks against teeth,
passsing food inbetween them inpasssing food inbetween them in
mastication.mastication.
Expelling air when the cheeks are distended.Expelling air when the cheeks are distended.

THE BUCCINATOR MECHANISMTHE BUCCINATOR MECHANISM
 FACTORS IN ENVIRONMENTAL BALANCE :FACTORS IN ENVIRONMENTAL BALANCE :
MUSCULATURE :MUSCULATURE :
A RESTING MUSCLE IS STILL PERFORMING A FUNCTION –A RESTING MUSCLE IS STILL PERFORMING A FUNCTION –
ENVIRONMENTAL FACTORS :ENVIRONMENTAL FACTORS :
CONTACT RELATIONSHIP AND RESISTANCECONTACT RELATIONSHIP AND RESISTANCE
OFFERED BY :OFFERED BY :
Buttressing effect of contiguous teeth.Buttressing effect of contiguous teeth.
Occlusal interdigitationOcclusal interdigitation
Bone building resorption balanceBone building resorption balance
Actual size and shape of roots of teethActual size and shape of roots of teeth
Total amount of periodontal fibresTotal amount of periodontal fibres

 STABILITY DEPENDS ON :STABILITY DEPENDS ON :
 GENETICGENETIC
 EPIGENETICEPIGENETIC
 ENVIONMENTALENVIONMENTAL
 MORPHOLOGICMORPHOLOGIC
 PHYSIOLOGIC FACTORSPHYSIOLOGIC FACTORS

Winders:Winders:
During mastication and deglutition, tongueDuring mastication and deglutition, tongue
may exertmay exert two or three times much force ontwo or three times much force on
the dentition as lipsthe dentition as lips and cheeks at any oneand cheeks at any one
time.time.

 Lear and Moorrees:Lear and Moorrees:
Substantiate the imbalance of buccolingualSubstantiate the imbalance of buccolingual
forces,forces,
Limitations –Limitations –
measuring equipmentmeasuring equipment
hydraulic nature of responsehydraulic nature of response
size of samplesize of sample
geometry of dental archgeometry of dental arch

 Proffit:Proffit:
Labial pressures are easier to measure thanLabial pressures are easier to measure than
lingual pressures.lingual pressures.
Fry (1960)Fry (1960)
Data for lingual pressure must be recordedData for lingual pressure must be recorded
with some suspicion.with some suspicion.

BUCCINATOR MECHANISMBUCCINATOR MECHANISM

TONGUETONGUE
 Muscular organ situated in the floor of the mouth.Muscular organ situated in the floor of the mouth.
 Associated with functions of taste, speech,Associated with functions of taste, speech,
Mastication and deglutition.Mastication and deglutition.

 Has two parts :Has two parts :
Oral part - lies in the mouth.Oral part - lies in the mouth.
Pharyngeal part -- lies in the pharynx.Pharyngeal part -- lies in the pharynx.
 These parts are separated by V –shaped sulcusThese parts are separated by V –shaped sulcus
k/a sulcus terminalis.k/a sulcus terminalis.
 External features:External features:
ROOT .ROOT .
TIP.TIP.
BODY.BODY.

ROOT ;ROOT ;
attached to mandible and soft palate aboveattached to mandible and soft palate above
hyoid bone below.hyoid bone below.
BODY –BODY –
upper surface – curved k/a dorsumupper surface – curved k/a dorsum..
Dorsum : divided into :Dorsum : divided into :
oral partoral part
pharyngeal partpharyngeal part
Inferior surface –Inferior surface – confined to oral partconfined to oral part..

PAPILLAE OF TONGUE :PAPILLAE OF TONGUE :
CIRCUMVALLATE PAPILLAECIRCUMVALLATE PAPILLAE
FUNGIFORM PAPILLAEFUNGIFORM PAPILLAE
FILIFORM / CONICAL PAPILLAEFILIFORM / CONICAL PAPILLAE

MUSCLES OF TONGUEMUSCLES OF TONGUE
INTRINSIC MUSCLESINTRINSIC MUSCLES
SUPERIOR LONGITUDINALSUPERIOR LONGITUDINAL
INFERIOR LONGITUDINALINFERIOR LONGITUDINAL
TRANSVERSETRANSVERSE
VERTICALVERTICAL

EXTRINSIC MUSCLES :EXTRINSIC MUSCLES :
GENIOGLOSSUSGENIOGLOSSUS
HYOGLOSSUSHYOGLOSSUS
STYLOGLOSSUSSTYLOGLOSSUS
PALATOGLOSSUSPALATOGLOSSUS

ARTERIAL SUPPLY :ARTERIAL SUPPLY :
LINGUAL ARTERY –LINGUAL ARTERY – EXTERNAL CAROTID ARTERYEXTERNAL CAROTID ARTERY
ROOT OF TONGUE –ROOT OF TONGUE – TONSILLAR AND ASCENDINGTONSILLAR AND ASCENDING
PHARYNGEAL ARTERIES.PHARYNGEAL ARTERIES.
VENOUS DRAIN :VENOUS DRAIN :
DEEP LINGUAL VEINDEEP LINGUAL VEIN

LYMPHATIC DRAINAGE :LYMPHATIC DRAINAGE :
TIP OF TONGUE –TIP OF TONGUE – bilaterally into submental nodes.bilaterally into submental nodes.
RIGHT AND LEFT HALVES –RIGHT AND LEFT HALVES – submandibular nodes.submandibular nodes.
POSTERIOR ONE- THIRD –POSTERIOR ONE- THIRD – jugulo-omohyoid nodes.jugulo-omohyoid nodes.

NERVE SUPPLY :NERVE SUPPLY :
MOTOR NERVEMOTOR NERVE ::
HYPOGLOSSAL NERVE --HYPOGLOSSAL NERVE -- ALL INTRINSIC ANDALL INTRINSIC AND
EXTRINSIC MUSCLES EXCEPTEXTRINSIC MUSCLES EXCEPT
PALATOGLOSSUSPALATOGLOSSUS
PALATOGLOSSUS –PALATOGLOSSUS – CRANIAL ROOT OF ACCESSORYCRANIAL ROOT OF ACCESSORY
NERVE THROUGHNERVE THROUGH
PHARNGEAL PLEXUSPHARNGEAL PLEXUS
SENSORY NERVESENSORY NERVE ::
LINGUAL NERVE –LINGUAL NERVE – NERVE OF GENERAL SENSATIONNERVE OF GENERAL SENSATION
CHORDA TYMPANI –CHORDA TYMPANI – NERVE OF TASTENERVE OF TASTE

DEVELOPMENT OF TONGUEDEVELOPMENT OF TONGUE
EPITHELIUM :EPITHELIUM :
ANTERIOR TWO-THIRDS –ANTERIOR TWO-THIRDS –
two lingual swellings , one tuberculum impar.two lingual swellings , one tuberculum impar.
arise from first branchial arch.arise from first branchial arch.
supplied by lingual nervesupplied by lingual nerve..
POSTERIOR ONE –THIRD –POSTERIOR ONE –THIRD –
cranial part of hypobranchial eminence.cranial part of hypobranchial eminence.
arise from third arch.arise from third arch.
supplied by glossopharyngeal nerve.supplied by glossopharyngeal nerve.

MUSCLES :MUSCLES :
OCCIPITAL MYOTOMES –OCCIPITAL MYOTOMES – hypoglossal nervehypoglossal nerve
CONNECTIVE TISSUE :CONNECTIVE TISSUE :
local mesenchyme.local mesenchyme.

MUSCLES OF MASTICATIONMUSCLES OF MASTICATION
MASSETERMASSETER
TEMPORALISTEMPORALIS
LATERAL PTERYGOIDLATERAL PTERYGOID
MEDIAL PTERYGOIDMEDIAL PTERYGOID

MASSETERMASSETER

LATERAL PTERYGOIDLATERAL PTERYGOID

 MUSCLES PRODUCING MOVEMENTSMUSCLES PRODUCING MOVEMENTS
DEPRESSIONDEPRESSION ::
LATERAL PTERYGOID,DIGASTRIC,LATERAL PTERYGOID,DIGASTRIC,
GENIOHYOID, MYLOHYOIDGENIOHYOID, MYLOHYOID
– ELEVATIONELEVATION::
MASSETER, TEMPORALIS,MASSETER, TEMPORALIS,
– PROTUSIONPROTUSION ::
LATERAL ,MEDIAL PTERYGOIDLATERAL ,MEDIAL PTERYGOID
– RETRACTIONRETRACTION ::
POSTERIOR FIBRES OF TEMPORALISPOSTERIOR FIBRES OF TEMPORALIS
– LATERAL OR SIDE MOVEMENTSLATERAL OR SIDE MOVEMENTS ::
LEFT LATERAL PTERYGOID AND RIGHT MEDIALLEFT LATERAL PTERYGOID AND RIGHT MEDIAL
PTERYGOIDPTERYGOID

TEMPOROMANDIBULAR JOINTTEMPOROMANDIBULAR JOINT
IS A SYNOVIAL JOINT OF CONDYLAR VARIETY.IS A SYNOVIAL JOINT OF CONDYLAR VARIETY.

ARTICULAR SURFACES:ARTICULAR SURFACES:
UPPER ARTICULAR SURFACE :UPPER ARTICULAR SURFACE :
ARTICULAR EMINENCEARTICULAR EMINENCE
ANTERIOR PART OF MANDIBULAR FOSSAANTERIOR PART OF MANDIBULAR FOSSA
LOWER ARTICULAR SURFACE :LOWER ARTICULAR SURFACE :
HEAD OF MANDIBLEHEAD OF MANDIBLE

LIGAMENTS:LIGAMENTS:
FIBROUS CAPSULEFIBROUS CAPSULE
LATERAL LIGAMENTLATERAL LIGAMENT
SPHENOMANDIBULAR LIGAMENTSPHENOMANDIBULAR LIGAMENT
STYLOMANDIBULAR LIGAMENTSTYLOMANDIBULAR LIGAMENT

 FIBROUS CAPSULEFIBROUS CAPSULE
 ATTACHED ABOVE :ATTACHED ABOVE :
Articular tubercleArticular tubercle
Circumference of mandibular fossaCircumference of mandibular fossa
Squamotympanic fissureSquamotympanic fissure
BELOW ;BELOW ;
Neck of condyle.Neck of condyle.

 LATERAL/TEMPOROMANDIBULARLATERAL/TEMPOROMANDIBULAR
LIGAMENT :LIGAMENT :
Reinforces and strengthens lateral part .Reinforces and strengthens lateral part .
 Fibres directed downwards and backwards.Fibres directed downwards and backwards.
 Attached above :Attached above :
articular tuberclearticular tubercle
Below :Below :
posterolateral aspect of neck of condyleposterolateral aspect of neck of condyle

SPHENOMANDIBULAR LIGAMENTSPHENOMANDIBULAR LIGAMENT
 Accessory ligament.Accessory ligament.
 Lies on deep plane awayLies on deep plane away
fromfibrous capsule.fromfibrous capsule.
 ATTACHED SUPERIORLY :ATTACHED SUPERIORLY :
 Spine of sphenoid.Spine of sphenoid.
 INFERIORLY ;INFERIORLY ;
 Lingula of mandibular foramen.Lingula of mandibular foramen.

STYLOMANDIBULAR LIGAMENTSTYLOMANDIBULAR LIGAMENT
 ACCESSORY LIGAMENT.ACCESSORY LIGAMENT.
 ATTACHED ABOVE :ATTACHED ABOVE :
Lateral surface of styloid processLateral surface of styloid process
 BELOW :BELOW :
Angle and posterior border of ramus of mandible.Angle and posterior border of ramus of mandible.

 ARTICULAR DISCARTICULAR DISC
OVAL FIBROUS PLATEOVAL FIBROUS PLATE
DIVIDES JOINT INTO:DIVIDES JOINT INTO:
UPPER COMPARTMENTUPPER COMPARTMENT
PERMITS GLIDINGPERMITS GLIDING
MOVEMENTSMOVEMENTS
LOWER COMPARTMENTLOWER COMPARTMENT
ROTATORY AND GLIDINGROTATORY AND GLIDING
MOVEMENTSMOVEMENTS

ARTERIAL SUPPLYARTERIAL SUPPLY
SUPERFICIAL TEMPORAL ARTERYSUPERFICIAL TEMPORAL ARTERY
MAXILLARY ARTERYMAXILLARY ARTERY
NERVE SUPPLYNERVE SUPPLY
AURICULOTEMPORAL NERVEAURICULOTEMPORAL NERVE
MASSETERIC NERVEMASSETERIC NERVE

 MOVEMENTS OF TMJMOVEMENTS OF TMJ
BETWEEN UPPER ARTICULAR SURFACEBETWEEN UPPER ARTICULAR SURFACE
AND ARTICULAR DISCAND ARTICULAR DISC
(MENISCOTEMPORAL COMPARTMENT)(MENISCOTEMPORAL COMPARTMENT)
BETWEEN DISC AND HEAD OF MANDIBLEBETWEEN DISC AND HEAD OF MANDIBLE

 PROTRACTION OF MANDIBLEPROTRACTION OF MANDIBLE
– Articular disc glides forwards over upperArticular disc glides forwards over upper
articular surface, head of mandible movingarticular surface, head of mandible moving
with it.with it.
– Reversal of this movement is c/a retraction.Reversal of this movement is c/a retraction.

SLIGHT OPENING OF THE MANDIBLESLIGHT OPENING OF THE MANDIBLE
 Head of the mandible moves on the undersurfaceHead of the mandible moves on the undersurface
of the disc like a hinge.of the disc like a hinge.

WIDE OPENING OF MANDIBLEWIDE OPENING OF MANDIBLE
 Hinge like movement is followed by gliding of theHinge like movement is followed by gliding of the
disc and head of the mandible as in protraction.disc and head of the mandible as in protraction.
 At the end of this movement, head comes to lieAt the end of this movement, head comes to lie
under articular tubercle.under articular tubercle.

CHEWING MOVEMENTSCHEWING MOVEMENTS
 Involve side to side movements of mandible.Involve side to side movements of mandible.
 Head of right side glides forward along the disc asHead of right side glides forward along the disc as
in protraction,in protraction,
 Head of the left side rotates on vertical axis.Head of the left side rotates on vertical axis.
 As a result chin moves forwards and to left sideAs a result chin moves forwards and to left side

 MUSCLES PRODUCING MOVEMENTSMUSCLES PRODUCING MOVEMENTS
DEPRESSION : LATERAL PTERYGOID , DIGASTRICDEPRESSION : LATERAL PTERYGOID , DIGASTRIC
GENIOHYOID,MYLOHYOIDGENIOHYOID,MYLOHYOID
ELEVATION: MASSETER, TEMPORALIS,MEDIALELEVATION: MASSETER, TEMPORALIS,MEDIAL
PTERYGOIDPTERYGOID
PROTUSION : LATERAL ,MEDIAL PTERYGOIDPROTUSION : LATERAL ,MEDIAL PTERYGOID
RETRACTION : POSTERIOR FIBRES OOFRETRACTION : POSTERIOR FIBRES OOF
LATERAL OR SIDE MOVEMENTS ; LEFT LATERALLATERAL OR SIDE MOVEMENTS ; LEFT LATERAL
PTERYGOID AND RIGHT MEDIAL PTERRYGOIDPTERYGOID AND RIGHT MEDIAL PTERRYGOID

FUNCTIONAL MOVEMENTSFUNCTIONAL MOVEMENTS
The mandible is the only movable boneThe mandible is the only movable bone
in the head and face and can onlyin the head and face and can only
be moved in certain directionsbe moved in certain directions
because of limitations of morphologybecause of limitations of morphology
And structure of temporomandibularAnd structure of temporomandibular
articulation.articulation.

OPENING MOVEMENT OF THE MANDIBLEOPENING MOVEMENT OF THE MANDIBLE
Condyle brought downward and forward as chinCondyle brought downward and forward as chin
drops downward and backward.drops downward and backward.
Gravity and primary contraction of lateral pterygoidGravity and primary contraction of lateral pterygoid
muscles.muscles.
Stabilizing and adjusting activity seen inStabilizing and adjusting activity seen in
suprahyoid ,infrahyoid groups ,in the geniohyoid ,suprahyoid ,infrahyoid groups ,in the geniohyoid ,
mylohyoid, and digastric muscles.mylohyoid, and digastric muscles.
Stylohyoid muscle changes in length.Stylohyoid muscle changes in length.

Hyoid bone moves downward and backwards.Hyoid bone moves downward and backwards.
Temporal , masseter and medial pterygoid musclesTemporal , masseter and medial pterygoid muscles
show relaxation – opening movement smooth.show relaxation – opening movement smooth.
(paralysis of these makes opening movement jerky(paralysis of these makes opening movement jerky
and uncontrolled).and uncontrolled).
Articular disc brought forward by lateral pterygoidArticular disc brought forward by lateral pterygoid
muscle and capsular ligaments as condyle rotatesmuscle and capsular ligaments as condyle rotates
against inferior surface of the disk.against inferior surface of the disk.

CLOSING MOVEMENT OF THE MANDIBLECLOSING MOVEMENT OF THE MANDIBLE
More power is elicited on mandibular closure.More power is elicited on mandibular closure.
Hyoid bone moves upward and forward .Hyoid bone moves upward and forward .
Controlled relaxation of lateral pterygoid musclesControlled relaxation of lateral pterygoid muscles
helps in smooth closure of mandible.helps in smooth closure of mandible.

PROTUSION OF THE MANDIBLEPROTUSION OF THE MANDIBLE
Brought about when medial and lateral pterygoidBrought about when medial and lateral pterygoid
muscles contract in unison, in conjunction withmuscles contract in unison, in conjunction with
controlled stabilizing relaxation of opening muscles.controlled stabilizing relaxation of opening muscles.

RETRUDING ACTION OF MANDIBLERETRUDING ACTION OF MANDIBLE
By contraction of posterior fibres of temporalisBy contraction of posterior fibres of temporalis
muscles with some assistance from geniohyoid ,muscles with some assistance from geniohyoid ,
digastric and mylohyoid muscles.digastric and mylohyoid muscles.
Hyoid bone moves posteriorly.Hyoid bone moves posteriorly.
Electromyographic research indicates that deepElectromyographic research indicates that deep
fibres of masster muscle assist in retrusion of thefibres of masster muscle assist in retrusion of the
mandible.mandible.

WORKING BITEWORKING BITE
To establish a working bite , the mandible must beTo establish a working bite , the mandible must be
moved to the right or left.moved to the right or left.
This lateral movement is initiated by the contractionThis lateral movement is initiated by the contraction
of lateral pterygoid muscles on one side andof lateral pterygoid muscles on one side and
relaxation on the opposite side.relaxation on the opposite side.

As the teeth are brought closure to an end to endAs the teeth are brought closure to an end to end
relationship, masseter contracts on left side,relationship, masseter contracts on left side,
assisting in ipsilateral activity.assisting in ipsilateral activity.
As the teeth are brought together , strong activity isAs the teeth are brought together , strong activity is
elicited in both masseter and temporalis muscleselicited in both masseter and temporalis muscles
on both sides.on both sides.

BENNETT MOVEMENTBENNETT MOVEMENT
In the lateral shift of the mandible, the articular diskIn the lateral shift of the mandible, the articular disk
moves toward the side of the working bite.moves toward the side of the working bite.
The condyle movesThe condyle moves
slightly laterallyslightly laterally
and rotates on theand rotates on the
working side.working side.

Primary contraction in the middle and posterior fibresPrimary contraction in the middle and posterior fibres
of temporalis muscle and in the posterior fibres ofof temporalis muscle and in the posterior fibres of
masseter and some increased activity in hyoidmasseter and some increased activity in hyoid
group.group.
BALANCING SIDE :BALANCING SIDE :
Condyle and disc moves downward and forward onCondyle and disc moves downward and forward on
the articular eminencethe articular eminence
Muscle activity consists largely of lateral pterygoidMuscle activity consists largely of lateral pterygoid
contraction and controlled relaxation of masseter ,contraction and controlled relaxation of masseter ,
temporalis and suprahyoid group.temporalis and suprahyoid group.

POSITIONS OF THE MANDIBLEPOSITIONS OF THE MANDIBLE

Posselt recorded graphically various positions andPosselt recorded graphically various positions and
movement area in sagittal planemovement area in sagittal plane

POSTURAL RESTING POSITIONPOSTURAL RESTING POSITION
In infants ,muscles associated with suckling orIn infants ,muscles associated with suckling or
intake of food are well developed from theintake of food are well developed from the
beginning.beginning.
When child is not engaged in taking food,mandibleWhen child is not engaged in taking food,mandible
assumes position of rest whether the teeth areassumes position of rest whether the teeth are
present or not.present or not.

Mandibular resting position is one of the earliestMandibular resting position is one of the earliest
positions to be developed.positions to be developed.
Mandible is suspended fromMandible is suspended from
cranial base bycranial base by
cradling musculature.cradling musculature.

Posselt observes that “Posselt observes that “ Postural position can bePostural position can be
altered by conditions in masticatory system as wellaltered by conditions in masticatory system as well
as by systemic factors.”as by systemic factors.”
Factors influencing postural position :Factors influencing postural position :
Body and head position.Body and head position.
SleepSleep
Psychic factors influencing muscle tonusPsychic factors influencing muscle tonus
AgeAge
Proprioception from the dentition and muscles.Proprioception from the dentition and muscles.
Occlusal changes.Occlusal changes.
Pain.Pain.
Psychic factors.Psychic factors.
Temporomandibular joint disease.Temporomandibular joint disease.

CENTRIC RELATIONCENTRIC RELATION
Refers to the position ofRefers to the position of
the mandibular condylethe mandibular condyle
in the articular fossa.in the articular fossa.
Defined as:Defined as:
unstrained ,neutral position of the mandible inunstrained ,neutral position of the mandible in
which the antero- superior surfaces of thewhich the antero- superior surfaces of the
mandibular condylesmandibular condyles are in contact with theare in contact with the
concavities of articular discs as they approximateconcavities of articular discs as they approximate
the postero- inferior third of their respectivethe postero- inferior third of their respective
articular eminentia.articular eminentia.

Can be the same as postural resting position, initialCan be the same as postural resting position, initial
occlusal contact and centric occlusion.occlusal contact and centric occlusion.
Centric occlusion requires contact of teeth inCentric occlusion requires contact of teeth in
addition to unstrained position whereas centricaddition to unstrained position whereas centric
relation does not require occlusal contact.relation does not require occlusal contact.

INITIAL CONTACTINITIAL CONTACT
In normal occlusion :In normal occlusion :
It maintains centric relation position as far asIt maintains centric relation position as far as
articular fossae are concerned.articular fossae are concerned.
movement in TMJ is almost completely rotation ofmovement in TMJ is almost completely rotation of
condyle.condyle.
the point of initial contact produces no change inthe point of initial contact produces no change in
function of TMJ.function of TMJ.

Initial contact in the idealInitial contact in the ideal
individual is usuallyindividual is usually
synonymoussynonymous
with centric occlusion.with centric occlusion.
In malocclusion or premature contact, initial contactIn malocclusion or premature contact, initial contact
is no longer the same as centric occlusion.is no longer the same as centric occlusion.

CENTRIC OCCLUSIONCENTRIC OCCLUSION
Implies a state of balance .Implies a state of balance .
must be harmoniousmust be harmonious
with centric relationwith centric relation

Premature contacts , loss of teeth ,overeruption ofPremature contacts , loss of teeth ,overeruption of
teeth , overextension of artificial restorations ,teeth , overextension of artificial restorations ,
Malpositions of individual teeth -- mitigateMalpositions of individual teeth -- mitigate
against centric occlusion.against centric occlusion.

MOST RETRUDED POSTIONMOST RETRUDED POSTION
(TERMINAL HINGE POSITION(TERMINAL HINGE POSITION))
To establish mandibularTo establish mandibular
and maxillaryand maxillary
casts in their propercasts in their proper
positions on the articulatorpositions on the articulator..

starting point in occlusal analysis andstarting point in occlusal analysis and
rehabilitation.rehabilitation.
Many dentists believe that by forcing theMany dentists believe that by forcing the
mandible into its most posterior position , it ismandible into its most posterior position , it is
easier to eliminate occlusal prematurities thateasier to eliminate occlusal prematurities that
exists.exists.

MOST PROTRUDED POSITIONMOST PROTRUDED POSITION
More variable from individualMore variable from individual
to individual.to individual.
Condyle drawn anterior toCondyle drawn anterior to
lowest point of articular eminence.lowest point of articular eminence.

HABITUAL RESTING POSITIONHABITUAL RESTING POSITION
May not be the same as postural resting position.May not be the same as postural resting position.
Pathologic conditions that interfere in establishmentPathologic conditions that interfere in establishment
of normal postural position of the mandible are :of normal postural position of the mandible are :
Abnormal atmospheric pressure.Abnormal atmospheric pressure.
Paralysis induced by poliomyelitisParalysis induced by poliomyelitis
Enlarged adenoidsEnlarged adenoids
PainPain
TMJ pathologyTMJ pathology
TraumaTrauma
Mouth breathingMouth breathing

HABITUAL OCCLUSAL RELATIONHABITUAL OCCLUSAL RELATION
In normal occlusion, centric occlusion and habitualIn normal occlusion, centric occlusion and habitual
occlusion should be the same.occlusion should be the same.
Occlusal relationship is much more susceptible :Occlusal relationship is much more susceptible :
Environmental assaultsEnvironmental assaults
Functional aberrationsFunctional aberrations
improper restoration of carious teethimproper restoration of carious teeth
Tooth lossTooth loss
Malposition of individual teethMalposition of individual teeth
Premature contacts.Premature contacts.

FUNCTIONS OFFUNCTIONS OF
STOMATOGNATIC SYSTEMSTOMATOGNATIC SYSTEM

MASTICATIONMASTICATION::
Mastication in infantsMastication in infants

MASTICATION IN ADULTSMASTICATION IN ADULTS
FLETCHER – masticatory stroke in adult using
six phases ; outlined by MURPHY.
PHASES:
PREPARATORY PHASE
FOOD CONTACT
CRUSHING PHASE
TOOTH CONTACT
GRINDING PHASE
CENTRIC OCCLUSION

DEGLUTITIONDEGLUTITION

FLETCHER --FLETCHER -- divided deglutitional cycle into :divided deglutitional cycle into :
Preparatory swallow.
Oral phase of swallowing.
Pharyngeal phase of swallowing.
Esophageal phase of swallowing.

PREPARATORY SWALLOWPREPARATORY SWALLOW ::

ORAL PHASE :ORAL PHASE :

PHARYNGEAL PHASE :PHARYNGEAL PHASE :

ESOPHAGEAL PHASE :ESOPHAGEAL PHASE :

TONGUE THRUSTTONGUE THRUST
Condition in which tongue makes contact with any teethCondition in which tongue makes contact with any teeth
anterior to the molars during swallowing.anterior to the molars during swallowing.

Factors :Factors :
Genetic .Genetic .
Learned behaviour (habit).Learned behaviour (habit).
Maturational.Maturational.
Mechanical restrictions.Mechanical restrictions.
Neurological disturbance.Neurological disturbance.
Psychogenic factors.Psychogenic factors.

OTHER TITLES FOR TONGUE THRUSTINGOTHER TITLES FOR TONGUE THRUSTING ::
PERVERTED OR DEVIATE SWALLOW.PERVERTED OR DEVIATE SWALLOW.
REVERSE SWALLOW.REVERSE SWALLOW.
RETAINED INFANTILE SWALLOW.RETAINED INFANTILE SWALLOW.
TOOTH APART SWALLOW.TOOTH APART SWALLOW.

CLASSIFICATION OF TONGUE THRUSTINGCLASSIFICATION OF TONGUE THRUSTING
BY JAMES S. BRANER AND HOLT :BY JAMES S. BRANER AND HOLT :
TYPE I : Non – deforming tongue thrust.TYPE I : Non – deforming tongue thrust.
TYPE II : Deforming anterior tongue thrust.TYPE II : Deforming anterior tongue thrust.
subgroup 1 : Anterior openbite.subgroup 1 : Anterior openbite.
subgroup 2 : Anterior proclination.subgroup 2 : Anterior proclination.
subgroup 3 : Posterior crossbite.subgroup 3 : Posterior crossbite.

TYPE III : Deforming lateral tongue thrust.TYPE III : Deforming lateral tongue thrust.
subgroup 1 : Posterior openbite.subgroup 1 : Posterior openbite.
subgroup 2 : Posterior crossbite.subgroup 2 : Posterior crossbite.
subgroup 3 : Deep overbite.subgroup 3 : Deep overbite.
TYPE IV : Deforming anterior and lateral tongue thrust.TYPE IV : Deforming anterior and lateral tongue thrust.
subgroup 1 : Anterior and posterior open bite.subgroup 1 : Anterior and posterior open bite.
subgroup 2 : Proclination of anterior teeth.subgroup 2 : Proclination of anterior teeth.
subgroup 3 : Posterior cross bite.subgroup 3 : Posterior cross bite.

Also classified as :Also classified as :
SIMPLE TONGUE THRUSTSIMPLE TONGUE THRUST
COMPLEX TONGUE THRUSTCOMPLEX TONGUE THRUST

RESPIRATIONRESPIRATION

Mouth breathingMouth breathing
classified as :classified as :
Obstructive .Obstructive .
Habitual .Habitual .
Anatomic .Anatomic .

Clinical featuresClinical features ::
Adenoid faces.Adenoid faces.

ManagementManagement ::
Removal of nasal and pharyngealRemoval of nasal and pharyngeal
obstruction.obstruction.
Interception of habit.Interception of habit.
Rapid maxillary expansion.Rapid maxillary expansion.

SPEECHSPEECH
defined as ordered utterance of a language.defined as ordered utterance of a language.

Vowels : a e I o uVowels : a e I o u
Consonants :p,g,m,b,s,t,r,z.Consonants :p,g,m,b,s,t,r,z.
Bilabial sounds :Bilabial sounds :
b, p, m.b, p, m.
Labiodental sounds :Labiodental sounds :
f , v.f , v.

Linguodental sounds :Linguodental sounds :
th.th.
Linguoalveolar sounds :Linguoalveolar sounds :
t,d,s,z,v,l.t,d,s,z,v,l.
sibilants : s ,z ,ch ,sh.sibilants : s ,z ,ch ,sh.
Linguopalatal and linguovelar sounds :Linguopalatal and linguovelar sounds :
year, she, vision, onion.year, she, vision, onion.
k ,g , ng.k ,g , ng.

LINGUOALVEOLAR SOUNDSLINGUOALVEOLAR SOUNDS

Classification of consonants :Classification of consonants :
Plosive or stop plosives :Plosive or stop plosives :
/p/,/b/,t/,/d/,/k/,/g/./p/,/b/,t/,/d/,/k/,/g/.
Fricatives :Fricatives :
/f/,/v/,/th/,/s/,/z/,/sh/./f/,/v/,/th/,/s/,/z/,/sh/.
Affricatives :Affricatives :
/ch/,/dz//ch/,/dz/
Glides :Glides :
/l/,/w/,/r/,/j/./l/,/w/,/r/,/j/.
Nasals :Nasals :
/n/,/m/,/ng/./n/,/m/,/ng/.

Speech mechanisms acts on breath stream in no. ofSpeech mechanisms acts on breath stream in no. of
ways :ways :
Controlling the air mechanism.Controlling the air mechanism.
Air direction.Air direction.
Air flow.Air flow.
Air release.Air release.
Air pressure.Air pressure.
General air path andGeneral air path and
Lingual airpath.Lingual airpath.

REFERENCESREFERENCES
 T.M GRABER-T.M GRABER- ORTHODONTICS:PRINCIPLES AND PRACTICEORTHODONTICS:PRINCIPLES AND PRACTICE
III Ed.III Ed.
 BONE BIODYNAMICS IN ORTHODONTIC AND ORTHOPAEDICBONE BIODYNAMICS IN ORTHODONTIC AND ORTHOPAEDIC
TREATMENTTREATMENTVOL 27 CRANIOFACIAL GROWTH SERIESVOL 27 CRANIOFACIAL GROWTH SERIES
 PROFFIT-PROFFIT- CONTEMPORARY ORTHODONTICS III Ed.CONTEMPORARY ORTHODONTICS III Ed.
 STRANG-STRANG- TEXTBOOK OF ORTHODONTIATEXTBOOK OF ORTHODONTIA
 MICHAEL.H.ROSS, EDWARD.J.REITH-MICHAEL.H.ROSS, EDWARD.J.REITH-HISTOLOGY, A TEXTHISTOLOGY, A TEXT
AND ATLASAND ATLAS

 WILLIAM.F.GANONGWILLIAM.F.GANONG-REVIEW OF MEDICAL-REVIEW OF MEDICAL
PHYSIOLOGY 20PHYSIOLOGY 20THTH
Ed.Ed.
 GRANT’SGRANT’S ANATOMY- ATLASANATOMY- ATLAS
 GRAY’SGRAY’S ANATOMYANATOMY
 SALZMANN-SALZMANN-ORTHODONTICS IN DAILY PRACTICEORTHODONTICS IN DAILY PRACTICE
 HOUSTON,STEPHAN,TULLEY-HOUSTON,STEPHAN,TULLEY-TEXTBOOK OFTEXTBOOK OF
ORTHODONTICSORTHODONTICS
 ANGLE ORTHODONTIST(1994)-ANGLE ORTHODONTIST(1994)-WOLFF’S LAWWOLFF’S LAW

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