TEMPROMANDIBULAR JOINT AND MOVEMENTS MANDIBULAR [ T M J ]

TEMPROMANDIBULAR JOINT ANDMOVEMENTS MANDIBULAR[ T M J ]Is the articulation between the mandible and the cranium .It is a bilateral articulation .

AnatomyArticular fossa and eminence .Condylar head .Articular disc (meniscus). Articular capsule (capsular ligament) .TMJ ligament . Synovial membrane .

Muscles of masticationTemporalis .Masseter .Medial pterygoid .Lateral pterygoid .

TemporalisMasseter

THE BASIC MOVEMENTS OF THE MANDIELERotation Movement = hinge movement .Translation Movement(gliding movement.)

Hinge movement = rotationRotation movement = hinge movement.It is the rotation of the mandible around an imaginary hinge axis at the centers of the condyles.It occurs in the lower compartment of the joint

Gliding or translationIt is the body movement of the mandible.It occurs in the upper compartment.

Condyle in retroded .no movement positionCondyle performing rotation=hinge movementCondyle performing anterior translation=gliding.

intercusbal position from which hinge movement will start No TranslationSagittal view=lateral view

Translation

Protrosion movementIt is the forward movement of the mandible.The mandible does not move in pure forward movement.The mandible moves down ward and forward = Gliding = translation movement.It occurs when the mandible moves from retroded position to -edge to edge position- to- reverse over jet, of anterior teeth.

Excursive MovementsProtrusive No Posterior Contact The lower anterior teeth ride up the lingual of the maxillary anterior teeth as the jaw goes forward.

Incisal path

Condylar path

Condylar path inclination varies according to the amount of protrusion. a-b Sagittal condylar path inclination. Centric relation position of the condyle. 4-P. 4 mm protrusion.8P. 8 mm protrusion

No Translation

Translation

Posselts Figure

MPMOICPRCPHAMP = Maximal protrusionICP = Intercuspal positionRCP= Retruded Contact position HA = Hinge axisMO = Maximum opening EE=edge to edgePosselts FigureHabitual Arc of Closure

Edge to edge position.

Christensen Phenomena When the mandible moves to edge to edge position , separation occurs distally between the natural dentition or occlusion rims .Protrusive RecordThe protrusive relationship determines the angle of the horizontal condylar path

Anterior biting to reverse vertical overlap.

Lateral Movement .Working side = the side which the movement take placeLateral Movement . (non working side = the side which the mandible moves away from.Lateral movement of the mandible

The Condylar PathHorizontal Condylar Path .Lateral Condylar Path .The Condylar Path Angle .

2. Vertical relations.

Vertical Dimension of rest The vertical dimension of the face when the mandible is in rest position.

Vertical Dimension of occlusion The vertical dimension of the face when the teeth are in contact in centric occlusion.

Freeway space= V.D.R. V.D.O. = 2-4mm

The centric relationIt is the relation between the mandible and the maxilla when the mandible in the physiologic retroded position at the vertical dimension of occlusion.

Importance: it is the point from which all movemnt of the mandible will start and end must be recorded to arrange the teeth in this position

Thank you

*******An illustration of a protrusive excursion, with the mandible moving forward. The lower anterior teeth ride up the lingual of the maxillary anterior teeth as the jaw goes forward.*