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Mandibular Movements. Anatomy and Physiology of the Temporomandibular Joint. A close up view of the joint. Basic mandibular movements. The basic condylar movements are: Rotation
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Basic mandibular movements The basic condylar movements are: • Rotation in the lower compartment between the head of the condyle and the disk (without changing the position) • Translation in the upper compartment between the head and the condyle as one unit and the glenoidfossa
Terminal hinge axis Axis of rotation (tansverse, sagital ,vertical ) Terminal hinge axis • It is an imaginary line between the mandibularcondyle around which the condyle rotate during the early openning and late closing (centric relation)can be located arbitary,or by max face bow)
They are usually classified according to the main direction of movement. The starting position is the habitual intercuspal position, from this point the mandible can move into: Possible Mandibular Movements Opening and Closing Movement Lateral Movement Forward & Backward Movement
Opening and closing movement • the opening movement is carried on by 2 types of movements: • a) A hinge (rotary) movement between the heads of the condyles and the discs. • b) A gliding (sliding) movement between the discs and the condylar heads moving as one unit on the articular eminence. • N.B IN FIRST 4 TO 8 MM IS PURE ROTATION WHILE IN FURTHER OPENNING ROTATION AND TRANSLATION
Protrusion and Retrusion The mandible is carried horizontally forward as in moving the lower anterior teeth in front of the upper. This movement takes place principally in the upper joint. CONDYLE MOVE DOWNWARD AND FORWARD
Lateral movement In this movement one condyle ( working) mainly rotates, while the other condyle ( balancing) moves mainly downwards, forwards and medially. The mandible is capable to move as one unit from one side to the other. This bodily shift is called Bennett Movement
Bennett Movement B A L A N C I N G W O R K I N G
The inclination of the condylarpath Types : A- Sagittalcondylar path angle B- Lateral condylar path angle
Incisal Path It is the path traveled by the incisal point during the forward glide of the mandible from the intercuspal position towards the maximum forward positionon.
Incisal Angle It is the angle of inclination of a line extending through the incisal edge of upper and lower anterior teeth, to the horizontal plane.
The Incisal Path . The Incisal Path Angle . Vertical Overlap (overbite) Horizontal overlap The greater the amount of vertical overlap The greater the incisal angle The greater the amount of horizontal overlap The lesser the incisal angle
Envelope of motion • Posselt s figure
These are positions within the boundaries of border positions. The intra-border Positions