Finaltmj/certified fixed orthodontic courses by Indian dental academy

TEMPOROMANDIBULATEMPOROMANDIBULA
R JOINTR JOINT
INDIAN DENTAL ACADEMY
Leader in continuing Dental Education
www.indiandentalacademy.comwww.indiandentalacademy.com

CONTENTSCONTENTS
EVOLUTION
DEVELOPMENT
ANATOMY
PHYSIOLOGY
BIOMECHANICS

BICONDYLAR GINGLIMOARTHROIDAL COMPOUND JOINT

EVOLUTIONEVOLUTION OF TMJOF TMJ

THE LIVING VERTEBRATESTHE LIVING VERTEBRATES
CLASSCLASS EXAMPLEEXAMPLE
AgnathaAgnatha LampreysLampreys
CondrichthyesCondrichthyes SharksSharks
OsteichthyesOsteichthyes Bony fishesBony fishes
AmphibiaAmphibia Frogs, toadsFrogs, toads
ReptiliaReptilia Snakes, turtles, lizardsSnakes, turtles, lizards
AvesAves BirdsBirds

MAMMALIAMAMMALIA
ProtheriaProtheria PlatypusPlatypus
MetatheriaMetatheria MarsupialsMarsupials
EutheriaEutheria Placental mammalsPlacental mammals

SCHOOLS OF THOUGHTSCHOOLS OF THOUGHT
Morphological conceptMorphological concept
Suspension and suctionSuspension and suction
Support for ventilationSupport for ventilation
GeneticsGenetics

AGNATHAAGNATHA
Vertebrates without jawsVertebrates without jaws
Gill slits- Filtering and feedingGill slits- Filtering and feeding
Epiceratobranchial joint inEpiceratobranchial joint in
mordern sharksmordern sharks
Oral opening filtering

GNATHOSOMESGNATHOSOMES
Ist & IInd gilled arches- BrainIst & IInd gilled arches- Brain
IIIrd & IVth gilled arches- PrehensionIIIrd & IVth gilled arches- Prehension
CEPHALIZATIONCEPHALIZATION
Skin over the edges- TeethSkin over the edges- Teeth
Simple hinge joint- Quadrate-ArticularSimple hinge joint- Quadrate-Articular
Eudiarthroidial joint- True bony fishesEudiarthroidial joint- True bony fishes

JAW AND THE CRANIUMJAW AND THE CRANIUM
A . Gill SlitsA . Gill Slits
B. AutostylyB. Autostyly
D. Modified autostylyD. Modified autostyly
C. AmphistylyC. Amphistyly
E & F. HyostylyE & F. Hyostyly
G. HolostylyG. Holostyly

AMPHIBIAAMPHIBIA
Jaws – cartilagenous core withJaws – cartilagenous core with
blanket of dermal bonesblanket of dermal bones
Joints- Quadrate-ArticularJoints- Quadrate-Articular
eudiarthroidialeudiarthroidial

REPTILIAREPTILIA
Increase in the dentary boneIncrease in the dentary bone
in backward directionin backward direction
Increase in muscle size andIncrease in muscle size and
their mechanical advantagetheir mechanical advantage
Dentary-Squamosal joint replacesDentary-Squamosal joint replaces
Quadrate-Articular jointQuadrate-Articular joint
Temporalis- orgin & insertionTemporalis- orgin & insertion
Streptostylic suspensionStreptostylic suspension www.indiandentalacademy.comwww.indiandentalacademy.com

SEQUENCE OF CHANGESSEQUENCE OF CHANGES
Availability of particular diet
Variations in tooth form
Replacement of the old joint
Adaptation of the musculature
Response of the bone
Coordination activity of the joints

Why there was a need of formation ofWhy there was a need of formation of
new jointnew joint
Prey sizePrey size
Muscle force , mass and direction of muscle pullMuscle force , mass and direction of muscle pull
Complex pattern of muscle activityComplex pattern of muscle activity
Rigid lower jawRigid lower jaw
Greater range of movementsGreater range of movements

MAMMALIAMAMMALIA
EUTHERIA
CARNIVORE HERBIVORE RODENT HUMANS

PREHENSION
COMMUNITION
TEARING CRUSHING
CARNIVORE HERBIVORE
CUTTING
GNAWING GRINDING SLICING
FUNCTIONAL POWER STROKESFUNCTIONAL POWER STROKES

CARNIVORESCARNIVORES
Projecting jaws used for grabbingProjecting jaws used for grabbing
preyprey
Long lower jaws with no ramusLong lower jaws with no ramus
Large coronoid process andLarge coronoid process and
large temporalislarge temporalis
Horizontally expanded temporalHorizontally expanded temporal
fossafossa
Short zygomatic areaShort zygomatic area

CONDYLECONDYLE
Firmly fitted jointFirmly fitted joint

HERBIVORESHERBIVORES
Long jaws with long cheek teethLong jaws with long cheek teeth
and no caninesand no canines
Cheek teeth are set well posteriorCheek teeth are set well posterior
Jaw joint is fitted for wide, gliding andJaw joint is fitted for wide, gliding and
horizontal movementshorizontal movements
Small coronoid processSmall coronoid process
decreased temporal fossadecreased temporal fossa
Enormously lengthened masseterEnormously lengthened masseter
orginorgin www.indiandentalacademy.comwww.indiandentalacademy.com

Lateral movements of the jointLateral movements of the joint

RODENTSRODENTS
Large sharp edged chisel shapedLarge sharp edged chisel shaped
incisor teethincisor teeth
Long gap between incisors andLong gap between incisors and
cheek teethcheek teeth
Antero-posteriorly directed glenoidAntero-posteriorly directed glenoid
groovegroove
Less lateral movements of jointLess lateral movements of joint

HOMINIDSHOMINIDS
Upright postureUpright posture
Bipedal locomotion-IncreasedBipedal locomotion-Increased
manual dexteritymanual dexterity
Shrinkage and retraction of jawsShrinkage and retraction of jaws
Change of diet- OmnivoresChange of diet- Omnivores
Increase in brain sizeIncrease in brain size

TMJ IN PRIMATESTMJ IN PRIMATES
UnspecializedUnspecialized
SpecializedSpecialized
UniversalUniversal

inspiratoy
gills
expiratoy
LM
V
D
THE MUSCLESTHE MUSCLES

F
R
E
III ORDER LEVERIII ORDER LEVER

Reptile
Early mammal
Mammal

Shark
Lobe finned fish
Primitive amphibian

Primitive reptile
Primitive marsupial

Primitive primate
Chimpanzee
Man

CONDYLAR CARTILAGECONDYLAR CARTILAGE
Membranous bone with periosteumMembranous bone with periosteum
Pressure on the condylePressure on the condyle
Localized ischemic changesLocalized ischemic changes
Undifferentiated mesenchymal cellsUndifferentiated mesenchymal cells
Chondroblasts proliferationChondroblasts proliferation
Cartilage formationCartilage formation

INTERARTICULAR DISKINTERARTICULAR DISK
No separate cartilage
Enlargement of the dentary
Muscle from the pterygoid region
Attachment to the new joint

EVOLUTION & MOLECULAREVOLUTION & MOLECULAR
BIOLOGYBIOLOGY
Homeobox genes (HOX)Homeobox genes (HOX)
Neural crest cells – mid brainNeural crest cells – mid brain
Hox-free default in mandibular archHox-free default in mandibular arch
Myosin heavy chain (MYH)Myosin heavy chain (MYH)
Neural crest cells

DEVELOPMENT OF TMJDEVELOPMENT OF TMJ

MECKELS CARTILAGEMECKELS CARTILAGE
Cartilage of the first archCartilage of the first arch
Extent of the cartilageExtent of the cartilage

PRIMARY JOINTPRIMARY JOINT
66thth
week- formationweek- formation
88thth
week- supports the mandibleweek- supports the mandible
Dorsal end is continuous withDorsal end is continuous with
the developing ear ossiclesthe developing ear ossicles
1616thth
week- Ossicles undergoweek- Ossicles undergo
endochondral ossificationendochondral ossification
10 WEEKS

CONDYLECONDYLE
99thth
week- startweek- start
10-11 weeks- chondrifies10-11 weeks- chondrifies
1212thth
week- fuses with ramusweek- fuses with ramus
20 weeks- completion20 weeks- completion
9-10 WEEKSwww.indiandentalacademy.comwww.indiandentalacademy.com

11 WEEKS12 WEEKS12 WEEKS ONWARDS14 weeks

16 WEEKSAT BIRTH22 WEEKS

CARTILAGESCARTILAGES
PRIMARY SECONDARYwww.indiandentalacademy.comwww.indiandentalacademy.com

CHARACTERCHARACTER CONDYLARCONDYLAR
CARTILAGECARTILAGE
EPIPHYSEALEPIPHYSEAL
CARTILAGECARTILAGE
GROWTHGROWTH APPOSITIONALAPPOSITIONAL INTERSTITIALINTERSTITIAL
INTERMIDIATEINTERMIDIATE
LAYERLAYER
UNDIFFRENTIATEDUNDIFFRENTIATED CARTILAGE CELLSCARTILAGE CELLS
ORGANIZATION OFORGANIZATION OF
CELLSCELLS
RANDOMRANDOM LINEARLINEAR
MINERALIZATIONMINERALIZATION HYPERTROPHICHYPERTROPHIC
ZONEZONE
DEGENERATIVEDEGENERATIVE
ZONEZONE
INTRINSIC GROWTHINTRINSIC GROWTH
POTENTIALPOTENTIAL
ABSENTABSENT PRESENTPRESENT
RESPONSE TO MECH.RESPONSE TO MECH.
STIMULATIONSTIMULATION
MOREMORE LESSLESS
SPONGIOSASPONGIOSA ABSENTABSENT PRESENTPRESENT
Differences ….koski et al 1968

According to BAUME:According to BAUME:
Growth Center:Growth Center:
Is a site of endochondral ossification withIs a site of endochondral ossification with
tissue separating force,contributing to thetissue separating force,contributing to the
increase of skeletal mass.increase of skeletal mass.
Growth Site:Growth Site:
Regions of Periosteal or suture boneRegions of Periosteal or suture bone
formation and modeling resorption adaptiveformation and modeling resorption adaptive
to environmental influences.to environmental influences.

GROWTH OF THE CONDYLEGROWTH OF THE CONDYLE
Articular surface
Cartilage
Subchondral bone
Proliferative zone

ENDOCHONDRAL GROWTH OF CONDYLEENDOCHONDRAL GROWTH OF CONDYLE
Forces are compressive in natureForces are compressive in nature
Direction of growthDirection of growth
Periosteum adapts itself mainlyPeriosteum adapts itself mainly
to tensile forcesto tensile forces
Cartilage
Endochondral bone tissue
cortices

CLINICAL CONSIDERATIONSCLINICAL CONSIDERATIONS
7-11 weeks morphogenesis- teratogens7-11 weeks morphogenesis- teratogens
Regional adaptive growthRegional adaptive growth
Arrangement of the prechondroblast cellsArrangement of the prechondroblast cells

HENCE Condylar cartilage is –HENCE Condylar cartilage is –
SECONDARY IN EVOLUTIONSECONDARY IN EVOLUTION
SECONDARY IN DEVELOPMENTSECONDARY IN DEVELOPMENT
SECONDARY IN GROWTHSECONDARY IN GROWTH

GLENOID FOSSAGLENOID FOSSA
7-8 weeks - Develops earlier than the condyle7-8 weeks - Develops earlier than the condyle
1010thth
week- ossificationweek- ossification
22 weeks- medial and lateral walls22 weeks- medial and lateral walls
Shape of the fossaShape of the fossa

ARTICULAR CAPSULEARTICULAR CAPSULE
9-11 Weeks- first appearance9-11 Weeks- first appearance
1717thth
Week- differentiationWeek- differentiation
2626thth
Week- completionWeek- completion

ARTICULAR EMINENCEARTICULAR EMINENCE
77THTH
month- Formation of the trabeculaemonth- Formation of the trabeculae
8-9 months- Completion8-9 months- Completion

SUMMARY
TMJ is one of the last synovial joints to developTMJ is one of the last synovial joints to develop
Develops from two blastemaDevelops from two blastema
It has an fibro cartilage coveringIt has an fibro cartilage covering
Condyle is a primarily a growth siteCondyle is a primarily a growth site

TEMPOROMANDIBULAR JOINTTEMPOROMANDIBULAR JOINT

ANATOMY OF THE TMJANATOMY OF THE TMJ

JOINTSJOINTS
FIBROUS CARTILAGENOUS SYNOVIAL
SYNDESMOSES
GOMPHOSES
SYMPHYSES
SYNCHONDROSES
SYNARTHROSES

SYNOVIAL JOINTSYNOVIAL JOINT
Gross anatomyGross anatomy
Hyaline cartilageHyaline cartilage
Low frictionLow friction
Weeping lubricationWeeping lubrication

THE CONDYLETHE CONDYLE
Oval shaped structureOval shaped structure
15-20 mm M-L & 8-10 mm A-P15-20 mm M-L & 8-10 mm A-P
Poles of the condylePoles of the condyle
Long axisLong axis

GLENOID FOSSAGLENOID FOSSA
Squamous portion of the temporal boneSquamous portion of the temporal bone
23 mm M-L & 15 mm A-P23 mm M-L & 15 mm A-P
NOT a stress bearing portionNOT a stress bearing portion
RELATIONSRELATIONS

ARTICULAR EMINENTIAARTICULAR EMINENTIA
AnatomyAnatomy
Slopes- Anterior & PosteriorSlopes- Anterior & Posterior
Functional areaFunctional area

ARTICULAR DISKARTICULAR DISK
Zones of the diskZones of the disk
SurfacesSurfaces
Relations & attachmentsRelations & attachments
Significance of fibro cartilageSignificance of fibro cartilage
FunctionsFunctions

RETRODISCAL TISSUERETRODISCAL TISSUE
SUPERIOR
INFERIOR

FIBROUS CAPSULEFIBROUS CAPSULE
AttachmentsAttachments
Layers of the capsuleLayers of the capsule
FunctionsFunctions
capsule

CAPSULECAPSULE
fossa
capsule
condyle

LIGAMENTSLIGAMENTS
INTRINSIC EXTRINSIC
Temporomandibular lig
Collateral lig
Sphenomandibular lig
Stylomandibular lig
Pterygomandibular
raphe
Contra lateral TM
ligwww.indiandentalacademy.comwww.indiandentalacademy.com

TEMPOROMANDIBULARTEMPOROMANDIBULAR
LIGAMENTLIGAMENT
Two layersTwo layers
FunctionsFunctions

FUNCTION OF TM LIGAMENTFUNCTION OF TM LIGAMENT

COLLATERAL LIGAMENT
SPHENOMANDIBULAR LIGAMENT
ORGIN
INSERTION
RELATIONS
FUNCTIONS
STYLOMANDIBULAR LIGAMENT

BLOOD SUPPLYBLOOD SUPPLY

NERVE SUPPLYNERVE SUPPLY

HISTOLOGYHISTOLOGY
MACROSCOPICwww.indiandentalacademy.comwww.indiandentalacademy.com

ARTICULAR EMINENCE CONDYLE
MICROROSOPIC
GLENOID FOSSA

SYNOVIAL MEMBRANESYNOVIAL MEMBRANE
Vascular connective tissueVascular connective tissue
Retrodiscal tissuesRetrodiscal tissues
Type A cells- macrophagesType A cells- macrophages
Type-B cells- synovial fluid (80%)Type-B cells- synovial fluid (80%)
LUBRICATIONLUBRICATION
NUTRITIONNUTRITION

RADIOGRAPHIC ANATOMYRADIOGRAPHIC ANATOMY
TRANSCRANIALTRANSCRANIAL
PANORAMICPANORAMIC

ARTHROGRAPHYARTHROGRAPHY

CT IMAGINGCT IMAGING

MRI IMAGINGMRI IMAGING

PHYSIOLOGY OF TMJPHYSIOLOGY OF TMJ

NEUROANATOMYNEUROANATOMY
REFLEXES OF THE JOINTREFLEXES OF THE JOINT
PSYCHOLOGICAL ASPECTSPSYCHOLOGICAL ASPECTS

NEUROANATOMYNEUROANATOMY
SENSORY INERVATIONSENSORY INERVATION
Main nerve supply-Main nerve supply- Auriculotemporal nerve-Auriculotemporal nerve- Posterior & lateral partsPosterior & lateral parts
of the capsuleof the capsule
It has the richest innervationsIt has the richest innervations
Massetric & Deep temporalMassetric & Deep temporal –– medial parts of the capsulemedial parts of the capsule
Center of the disk and the articulating surfaces are not innervatedCenter of the disk and the articulating surfaces are not innervated

RECEPTOR INNERVATION OFRECEPTOR INNERVATION OF
TMJTMJ
FOUR TYPESFOUR TYPES
RUFFINIRUFFINI
GOLGI-TENDONGOLGI-TENDON
VATER PACINI CORPUSCLESVATER PACINI CORPUSCLES
FREE NERVE ENDINGSFREE NERVE ENDINGS

ANATOMICALANATOMICAL
DESIGNATIONDESIGNATION
FUNCTIONALFUNCTIONAL
DESIGNATIONDESIGNATION
REFLEX ROLEREFLEX ROLE LOCATIONLOCATION
RUFFINIRUFFINI
ENDINGENDING
StaticStatic
mechanoreceptormechanoreceptor
PosturePosture Post & posterioroPost & posterioro
-lateral aspects of-lateral aspects of
capsulecapsule
VATER-PACINIVATER-PACINI
CORPUSCLECORPUSCLE
DynamicDynamic
MovementMovement
acceleratoraccelerator
TM ligamentTM ligament
GOLGI TENDONGOLGI TENDON StaticStatic
Protection of theProtection of the
ligamentligament
TM ligamentTM ligament
FREE NERVEFREE NERVE
ENDINGENDING
Pain receptorPain receptor Protection of theProtection of the
jointjoint
DistributedDistributed
throughout thethroughout the
capsulecapsule

CENTRAL PROJECTIONCENTRAL PROJECTION

MOTOR INNERVATIONMOTOR INNERVATION
REFLEXES OF TMJ ORGINREFLEXES OF TMJ ORGIN
Inhibition in masserteric
discharge
Opening of
mandible
facilitation
Mandibular
closing
TONUS

JAW CLOSING REFLEXJAW CLOSING REFLEX
The stretch reflex of jaw closersThe stretch reflex of jaw closers
When the jaw is tapped muscle spindles of elevators are excitedWhen the jaw is tapped muscle spindles of elevators are excited
The A.P generated travel to the mesencephalic nucleusThe A.P generated travel to the mesencephalic nucleus
Travels to motor nucleusTravels to motor nucleus
Extra fusal fibers of the elevator muscleExtra fusal fibers of the elevator muscle

 FUNCTION- Maintenance of the jaw against gravity and theFUNCTION- Maintenance of the jaw against gravity and the
inertial loadinginertial loading
 MONOSYNAPTICMONOSYNAPTIC

JAW OPENING REFLEXJAW OPENING REFLEX
The flexor reflex of the jaw closersThe flexor reflex of the jaw closers
Reflex is activated biting into hard objectsReflex is activated biting into hard objects
A.P is carried to the spinal nucleusA.P is carried to the spinal nucleus
Interneurons synapse with motor nucleusInterneurons synapse with motor nucleus
Excitation of the depressorsExcitation of the depressors

FUNCTION- protection of the hard and soft tissuesFUNCTION- protection of the hard and soft tissues
POLYSYNAPTICPOLYSYNAPTIC

JAW UNLOADING REFLEXJAW UNLOADING REFLEX
Sudden breakage of the food itemSudden breakage of the food item
Sudden closing of the jawSudden closing of the jaw
Spindles are unloadedSpindles are unloaded
Elevators are inhibitedElevators are inhibited
Occlusion is preventedOcclusion is prevented

REFLEXES PROTECTING THE TMJREFLEXES PROTECTING THE TMJ
These reflexes ONLY operate to restrict EXTREME openingThese reflexes ONLY operate to restrict EXTREME opening
movementsmovements
Maximal opening could be increased with anesthesiaMaximal opening could be increased with anesthesia
Attenuation of discharge on the contralateral musclesAttenuation of discharge on the contralateral muscles
TMJ has no receptors that can monitor loading of the jointTMJ has no receptors that can monitor loading of the joint

REFLEXES PROTECTING THEREFLEXES PROTECTING THE
TEETHTEETH
Normal postion of the
mandible
Normal
closing
Balancing interference Mandibular deviation
Balancing interference
Position of the
mandible
Mandibular deviation
Position of the
mandible
Mandibular deviation

TMJ AND THE TONGUETMJ AND THE TONGUE
0 DEG- no change in genioglossus muscle0 DEG- no change in genioglossus muscle
21 < DEG- increased activity is seen21 < DEG- increased activity is seen
Infiltration of the anesthetic abolished the reflexInfiltration of the anesthetic abolished the reflex
Associated with the receptors monitoring the adequeacy of theAssociated with the receptors monitoring the adequeacy of the
ventilationventilation

PSYCHOLOGICAL ASPECTS OFPSYCHOLOGICAL ASPECTS OF
THE INERVATIONSTHE INERVATIONS
MANDIBULAR POSITION SENSEMANDIBULAR POSITION SENSE
Duplication of the mandibular movementDuplication of the mandibular movement
SIZE THRESHOLD- .01 MM of objectsSIZE THRESHOLD- .01 MM of objects

SUMMARYSUMMARY
Auriculotemporal nerve- lateral & posteriorlyAuriculotemporal nerve- lateral & posteriorly
Jaw muscle activity probably affects the sensitivity of receptorsJaw muscle activity probably affects the sensitivity of receptors
Its sensitivity is increased by inflammation and elevatedIts sensitivity is increased by inflammation and elevated
pressurespressures
Receptors cannot protect against excessive loadingReceptors cannot protect against excessive loading
Crucial massCrucial mass is more important thanis more important than Crucial mixCrucial mix

BIOMECHANICSBIOMECHANICS

MUSCLESMUSCLES
Microscopic featuresMicroscopic features
Arrangement of the muscle fibersArrangement of the muscle fibers

TYPES OF MUSCLE FIBERSTYPES OF MUSCLE FIBERS
SLOW MUSCLE FIBERS-SLOW MUSCLE FIBERS- TYPE ITYPE I
MASSETER & MEDIAL PTERYGOIDMASSETER & MEDIAL PTERYGOID
POST FIBERS OF THE TEMPORALISPOST FIBERS OF THE TEMPORALIS
LATERAL PTERYGOIDLATERAL PTERYGOID
FAST MUSCLE FIBERS-FAST MUSCLE FIBERS- TYPE IITYPE II
POST FIBERS OF MASSETER AND MEDIAL PTERYGOIDPOST FIBERS OF MASSETER AND MEDIAL PTERYGOID
TEMPORALIS SUPERFICIAL 50%TEMPORALIS SUPERFICIAL 50%
MUSCLES OF THE MASTICATIONMUSCLES OF THE MASTICATION
INTERMDIATE FIBERSINTERMDIATE FIBERS
TYPE II CTYPE II C

MUSCLES OF MASTICATIONMUSCLES OF MASTICATION

MASSETERMASSETER

FEATURESFEATURES SUPERFICIALSUPERFICIAL DEEPDEEP
ORGINORGIN Zygomatic processZygomatic process Anterior two thirds ofAnterior two thirds of
zygomatic archzygomatic arch
INSERTIONINSERTION Angle and lowerAngle and lower
portion of mandibleportion of mandible
Upper portion of theUpper portion of the
lateral aspect of ramuslateral aspect of ramus
ORIENTATIONORIENTATION Oblique downwardsOblique downwards Vertically downwardsVertically downwards
FUNCTIONSFUNCTIONS Protruding ofProtruding of
mandiblemandible
Stabilizing condyleStabilizing condyle
against the articularagainst the articular
eminenceeminence

TEMPORALISTEMPORALIS
Fan shaped muscleFan shaped muscle
ORIGIN- Temporal fossa & theORIGIN- Temporal fossa & the
lateral surface of the skulllateral surface of the skull
INSERTION- Forms a tendonINSERTION- Forms a tendon
inserts into coronoid process andinserts into coronoid process and
the anterior border of the ramusthe anterior border of the ramus

DIVISIONS-DIVISIONS-
ANTERIORANTERIOR - Directed vertically- Directed vertically
MIDDLEMIDDLE - Oblique orientation- Oblique orientation
POSTERIORPOSTERIOR - Horizontally- Horizontally
More concerned with moving and stabilizing the mandibleMore concerned with moving and stabilizing the mandible

MEDIAL PTERYGOIDMEDIAL PTERYGOID
ORIGIN- Medial portion of the lateral pterygoid plateORIGIN- Medial portion of the lateral pterygoid plate
- maxillary tuberosity- maxillary tuberosity
INSERTION- medial portion of the angle of mandibleINSERTION- medial portion of the angle of mandible
FUNCTIONS- Elevating and protrusion of the mandibleFUNCTIONS- Elevating and protrusion of the mandible
-Unilateral contraction mediotrusive movement-Unilateral contraction mediotrusive movement

LATERAL PTERYGOIDLATERAL PTERYGOID
Two divisions- INFERIOR LATERAL PTERYGOIDTwo divisions- INFERIOR LATERAL PTERYGOID
SUPERIOR LATERAL PTERYGOIDSUPERIOR LATERAL PTERYGOID
INFERIOR HEAD-INFERIOR HEAD-
ORIGIN- outer surface of the lateralORIGIN- outer surface of the lateral
pterygoid platepterygoid plate
INSERTION- neck of the condyleINSERTION- neck of the condyle
FUNCTIONS- Protrusion when contractsFUNCTIONS- Protrusion when contracts
simultaneouslysimultaneously
- Mediotrusive motion when- Mediotrusive motion when
contracts unilaterallycontracts unilaterally

SUPERIOR HEAD-SUPERIOR HEAD-
ORIGIN- Infratemporal surface of of theORIGIN- Infratemporal surface of of the
greater wing of the sphenoidgreater wing of the sphenoid
INSERTION- FOUR TYPESINSERTION- FOUR TYPES

I Insertion into the condyle by merging into the central tendonI Insertion into the condyle by merging into the central tendon
II Insert directly into pterygoid fovea(60 – 70 %)II Insert directly into pterygoid fovea(60 – 70 %)
III Blend with the fibers of the capsuleIII Blend with the fibers of the capsule
IV Insert directly into the medial portion of the disk (30 %)IV Insert directly into the medial portion of the disk (30 %)
FUNCTIONS-FUNCTIONS-
Active during the closing especially during theActive during the closing especially during the
power strokepower stroke

DIGASTRICSDIGASTRICS
POSTERIOR BELLY –POSTERIOR BELLY –
Origin- Mastoid notchOrigin- Mastoid notch
Fibers- Downwards forwards and inwardsFibers- Downwards forwards and inwards
Attachment- Hyoid boneAttachment- Hyoid bone
ANTERIOR BELLY-ANTERIOR BELLY-
Origin- Fossa of the lingual surface of theOrigin- Fossa of the lingual surface of the
mandiblemandible
Fibers- Downward and backwardFibers- Downward and backward
FUNCTION – Depression of the mandibleFUNCTION – Depression of the mandible

TYPES OF MOVEMENTTYPES OF MOVEMENT
ROTATIONAL MOVEMENTROTATIONAL MOVEMENT
HORIZONTAL AXISHORIZONTAL AXIS
FRONTAL AXISFRONTAL AXIS
SAGITTAL AXISSAGITTAL AXIS
TRANSLATIONAL MOVEMENTTRANSLATIONAL MOVEMENT
SINGLE PLANE BORDER MOVEMENTSSINGLE PLANE BORDER MOVEMENTS

HORIZONTAL AXISHORIZONTAL AXIS
HINGE AXIS

FRONTAL AXISFRONTAL AXIS

SAGITTAL AXISSAGITTAL AXIS

TRANSLATION MOVEMENTTRANSLATION MOVEMENT
DefinitionDefinition
Occurs in the superior jointOccurs in the superior joint
cavitycavity
Both hinge and the translationBoth hinge and the translation
occurs simultaneouslyoccurs simultaneously

SAGITTAL PLANE BORDERSAGITTAL PLANE BORDER
MOVEMENTSMOVEMENTS
FOUR COMPONENTSFOUR COMPONENTS
PosteriorPosterior
AnteriorAnterior
SuperiorSuperior
FunctionalFunctional

HORIZONTAL BORDERHORIZONTAL BORDER
MOVEMENTSMOVEMENTS
R L

FRONTAL BORDER MOVEMENTSFRONTAL BORDER MOVEMENTS

ENVELOPE OF MOTIONENVELOPE OF MOTION

BENNETT MOVEMENT & ANGLEBENNETT MOVEMENT & ANGLE

ARTICULAR DISK

SUMMARYSUMMARY
TEMPORALIS
MASSETER &
MEDIAL PTERYGOID
DIAGASTRIC
&
GENIOHYOID
LATERAL
PTERYGOID
ELEVATION
RETRACTION PROTRACTION
DEPRESSION

ARTHROSCOPY OF TMJARTHROSCOPY OF TMJ
Kenji Takagi Japan first introduced this techniqueKenji Takagi Japan first introduced this technique
Insertion of an rigid endoscope into the joint compartment forInsertion of an rigid endoscope into the joint compartment for
observation and therapeutic purposeobservation and therapeutic purpose
Arthrography is mandatory before this procedure- Joint spaceArthrography is mandatory before this procedure- Joint space

INSTRUMENTATIONINSTRUMENTATION
TV camera and videoTV camera and video
Scopes - 2.4, 1.9, 1.7 mmScopes - 2.4, 1.9, 1.7 mm
Sheath - 2.7, 2.4 , 2 mmSheath - 2.7, 2.4 , 2 mm
Light source – xenon arcLight source – xenon arc
illuminatorilluminator

TECHNIQUETECHNIQUE

NORMAL JOINTNORMAL JOINT

REFERENCESREFERENCES
LASKIN- Temporomandibular jointLASKIN- Temporomandibular joint
CARLSSON, SESSLE, MOHL,ZARB- Temporomandibular AndCARLSSON, SESSLE, MOHL,ZARB- Temporomandibular And
masticatory muscle disordersmasticatory muscle disorders
BERKOVITZ- Oral anatomyBERKOVITZ- Oral anatomy
J.P OKESON- Temporomandibular disordersJ.P OKESON- Temporomandibular disorders

IDE NAKAZAWA –Anatomical atlas of TMJIDE NAKAZAWA –Anatomical atlas of TMJ
TENCATE – Oral histogyTENCATE – Oral histogy
Koski et al , 1968 AJO-DOKoski et al , 1968 AJO-DO
MAJOR M ASH-Wheelers dental anatomy, Physiology andMAJOR M ASH-Wheelers dental anatomy, Physiology and
occlussionocclussion

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