Transcript JAW RELATIONS AND MANDIBULAR MOVEMENTS

MANDIBULAR
MOVEMENTS
TMJ has a capsule and articulating disc
 Two joints are mechanically coupled
 Is a synovial joints,,its bony components
covered with dense fibrous tissue NOT by
hyaline cartilage
 Glenoid fossa of temporal bone & condyle
of mandible = articulating surface
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Articular disc divides joints into upper & lower
components
Upper components show anterior posterior
gliding movement
Lower components show hinge movement
TMJ is capable of function and Para function
movements
Movements are similar in dentulous and
edentulous patients
Occlusion in complete denture should be in
harmony with these movements
***`Mandible moves to carry out functions of
Mastication
Swallowing
Speech
Expression
Para functional habits
WHAT MUST I STUDY?????
TMJ ARTICULATION
Bony structures
Fossa & condyles
Ligaments
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Articular disc (meniscus)
Muscles
*****Ligaments (to limit motion in the joint)
Capsular ligament
 Tempromandibular ligament
 Sphenomandibular ligament
 Stylomandibular ligament
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MUSCLES
Temporal muscle
Posterior part to retrude the mandible
Middle part elevates it in centric position
No biting force when mandible is in
protrusion, so it can be used to determine
whether the patient is closing in centric
relation.
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Medial pterygoid muscle
The action of the muscle is an elevator
Does not assist in the lateral or protrusive
movements
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Lateral petrygoid muscle
The principle action is the protrusion of one
or both condyles. It guides the mandible
into lateral or protrusive positions.
 Masseter
(elevation)
Remember : extension of buccal
flange (disto buccal)
MUSCLES OF DEPRESSION
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Suprahyoid
Geniohyoid
Mylohyoid
Stylohyoid
Platysma
Are the primary movers of the mandible
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Mylohyoid muscle
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Its principle action is to assist in
swallowing
Opposing teeth are in contact
Movements are controlled by
neuromuscular system as limited by the
condyles and the guide influences of the
contacting teeth
Opposing teeth are not in contact,
movements are controlled by musculature
as limited by condyles and ligaments.
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CLASSIFICATION OF JAW
RELATIONS
Orientation relation
Mandible can rotate in the sagittal plane
Vertical relations
Amount of jaw separation
Horizontal relation
Front to back and side to side
MANDIBULAR MOVEMENTS
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Rotation concentric circles around a
common axis
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Transolatory points of the body move in
the same velocity and direction
AXES OF ROTATION
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Saggital
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Vertical
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Transverse
Rotational Movement
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Around the sagittal axis
Rotational Movement
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Around the horizontal axis
Rotational Movement
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Around the frontal (vertical) axis
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Opening and closing movements
Lateral excursions
Protrusive movement
Bennett Movement & Angle
The angle formed by the
sagittal plane and the
path of the advancing
condyle during lateral
mandibular movements
as viewed in the
horizontal plane.
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