Myology related to prosthodontics/certified fixed orthodontic courses by Indian dental academy

MYOLOGY -
RELATED TO
PROSTHODONTIC
S
INDIAN DENTAL ACADEMY
Leader in continuing Dental
Education
www.indiandentalacademy.comwww.indiandentalacademy.com

OriginOrigin: Lateral surface of the skull: Lateral surface of the skull
InsertionInsertion: Coronoid process and anterior: Coronoid process and anterior
border of the ramusborder of the ramus
FunctionFunction : Elevates and retracts jaw: Elevates and retracts jaw
Assists in rotationAssists in rotation
Active in clenchingActive in clenching

OriginOrigin : Zygomatic Arch: Zygomatic Arch
InsertionInsertion : Angle of mandible: Angle of mandible
FunctionFunction : Elevates and protracts: Elevates and protracts
jawjaw
Assists in lateralAssists in lateral
movementsmovements
Active in clenchingActive in clenching

OriginOrigin :: Pterygoid fossa andPterygoid fossa and
mesialmesial surface of lateralsurface of lateral
pterygoidpterygoid plateplate
InsertionInsertion:: Medial surface of angle ofMedial surface of angle of
mandiblemandible
Function:Function: Elevates jaw, causesElevates jaw, causes
laterallateral movement andmovement and
protrusionprotrusion

OriginOrigin : Infra temporal surface of: Infra temporal surface of
greatergreater wing of sphenoidwing of sphenoid
InsertionInsertion: Articular capsule and: Articular capsule and
disc ,neckdisc ,neck of the condyleof the condyle
Function:Function: Position disc in closingPosition disc in closing
SUPERIOR LATERAL PTERYGOIDSUPERIOR LATERAL PTERYGOID

Origin :Origin : Lateral surface of lateralLateral surface of lateral
pterygoid platepterygoid plate
Insertion :Insertion : Neck of the condyleNeck of the condyle
Function:Function: Protrudes and depressesProtrudes and depresses
jawjaw causes lateralcauses lateral
movementsmovements

Origin :Origin : Inner surface of theInner surface of the
mandiblemandible
Insertion:Insertion: Hyoid and mylohyoidHyoid and mylohyoid
rapheraphe
Function :Function : Elevates and stabilizesElevates and stabilizes
hyoidhyoid

GENIOHYOIDGENIOHYOID
Origin :Origin : Genial tubercleGenial tubercle
Insertion:Insertion: HyoidHyoid
Function :Function : Elevates and draws hyoidElevates and draws hyoid
forwardforward

Origin :Origin : Tendon linked to hyoidTendon linked to hyoid
Insertion:Insertion: Digastric fossaDigastric fossa
Function:Function: Elevates hyoid,Elevates hyoid,
depressesdepresses jawjaw

MOVEMENTMOVEMENT MUSCLESMUSCLES
Elevation of chinElevation of chin
(closing)(closing)
MasseterMasseter
Medial pterygoidMedial pterygoid
Anterior part ofAnterior part of
temporalistemporalis
Depression of chinDepression of chin
(opening)(opening)
Lateral pterygoidLateral pterygoid
DigastricDigastric
Geniohyoid andGeniohyoid and
mylohyoid withmylohyoid with
infra hyoid musclesinfra hyoid muscles

MOVEMENTMOVEMENT MUSCLESMUSCLES
ProtractionProtraction Lateral pterygoidLateral pterygoid
Medial pterygoidMedial pterygoid
MasseterMasseter
RetractionRetraction TemporalisTemporalis
DigastricDigastric
ChewingChewing Medial and llateralMedial and llateral
pterygoidpterygoid
MasseterMasseter
TemporalisTemporaliswww.indiandentalacademy.comwww.indiandentalacademy.com

The muscles that hold move orThe muscles that hold move or
stabilize the mandible do sostabilize the mandible do so
because they receive impulsesbecause they receive impulses
from the central nervous system.from the central nervous system.
Mandibular motion at consciousMandibular motion at conscious
level results in voluntarylevel results in voluntary
movement where as atmovement where as at
subconscious level due tosubconscious level due to
stimulation of oral or musclestimulation of oral or muscle
receptors cause involuntaryreceptors cause involuntary
movement.movement. www.indiandentalacademy.comwww.indiandentalacademy.com

Receptors in the oral mucousReceptors in the oral mucous
membrane are stimulated bymembrane are stimulated by
touch pain thermal changes ortouch pain thermal changes or
pain and pressure where aspain and pressure where as
other receptors are principallyother receptors are principally
located in the periodontallocated in the periodontal
ligaments, mandibular musclesligaments, mandibular muscles
and ligaments provideand ligaments provide
information as to the location ofinformation as to the location of
mandible in space and thusmandible in space and thus

 Impulses form oral receptorsImpulses form oral receptors
Trigeminal nucleiTrigeminal nuclei
 From proprioceptorsFrom proprioceptors
Mesencephalic nuclei of the brainMesencephalic nuclei of the brain
From these 2 receptorsFrom these 2 receptors
Cerebral cortexCerebral cortex

 From the cerebral cortexFrom the cerebral cortex
It comes though three waysIt comes though three ways
Via the thalamus to the sensoriomotorVia the thalamus to the sensoriomotor
cortex (conscious level) to producecortex (conscious level) to produce
voluntary change in the position of thevoluntary change in the position of the
mandiblemandible
By way of a reflex arc to the motorBy way of a reflex arc to the motor
nuclei of the Trigeminal nerve to causenuclei of the Trigeminal nerve to cause
involuntary movementinvoluntary movement
By combination of the these two waysBy combination of the these two ways
through the subcortical areas as thethrough the subcortical areas as the
hypothalamus, basal ganglion.hypothalamus, basal ganglion.

 In edentulous patients the periodontalIn edentulous patients the periodontal
ligament are lost thus the source ofligament are lost thus the source of
control in the positioning of thecontrol in the positioning of the
mandible are lost thus to compensatemandible are lost thus to compensate
this centric occlusion must be inthis centric occlusion must be in
harmony with the centric relation andharmony with the centric relation and
meet evenly in the normal range ofmeet evenly in the normal range of
functional activity and these impulsesfunctional activity and these impulses
can be generated by voluntary thoughtcan be generated by voluntary thought
which are transmitted through thewhich are transmitted through the
motor nuclei and from there to themotor nuclei and from there to the
muscle of mastication so the mandiblemuscle of mastication so the mandible
performs the desired activityperforms the desired activitywww.indiandentalacademy.comwww.indiandentalacademy.com

Mastication is a programmedMastication is a programmed
event residing in a chewingevent residing in a chewing
centre located in the brain stemcentre located in the brain stem
(in the reticular formation of the(in the reticular formation of the
pons )pons )
The cyclic nature of masticationThe cyclic nature of mastication
(jaw opening and closure(jaw opening and closure
,tongue protrusion and,tongue protrusion and
retrusion) is aretrusion) is a resultresult of ofof of
action of this central patternaction of this central patternwww.indiandentalacademy.comwww.indiandentalacademy.com

The alteration of the chewingThe alteration of the chewing
pattern or character (rate,pattern or character (rate,
force, duration)are related toforce, duration)are related to
the consistency of the bolus ofthe consistency of the bolus of
the food.the food.
The relatively continuous flowThe relatively continuous flow
of impulses through theof impulses through the
specific pathway form thespecific pathway form the
receptors to the CNS and backreceptors to the CNS and back
to the musculature establishesto the musculature establishes
a memory pattern fora memory pattern for
mandibular movements.mandibular movements.www.indiandentalacademy.comwww.indiandentalacademy.com

Thus when natural teethThus when natural teeth areare
present a individual subpresent a individual sub
consciously develops theseconsciously develops these
memory patternsmemory patterns
But these patterns are disturbedBut these patterns are disturbed
when the teeth are lost or a newwhen the teeth are lost or a new
restoration is placed with anrestoration is placed with an
occlusion which is not inocclusion which is not in
harmony with mandibularharmony with mandibular
movement leads to painmovement leads to pain
,pathosis and mental stresswww.indiandentalacademy.comwww.indiandentalacademy.com

Myology related to prosthodontics/certified fixed orthodontic courses by Indian dental academy

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Myology related to prosthodontics/certified fixed orthodontic courses by Indian dental academy