Mandibular Movement Flashcards
What are the four anatomic determinants of mandibular movement?
- right TMJ
- left TMJ
- Teeth/occlusion
- Neuromusculature
What are the two different types of movements within the TMJ?
- rotational movement (inferior joint compartment)
- translational movement (superior joint compartment)
What is rotation within the TMJ?
- process of turning about the axis
- mouth opens and closes around a fixed point or axis within the condyles
Where does rotation occur?
within the inferior joint compartment (on the articular disk)
How far (mm) does rotation occur before translation begins?
20-25 mm of opening
What are the three reference planes that rotational movements of mandbile may occur in?
sagittal plane - horizontal axis
horizontal plane - vertical axis
frontal plane - sagittal axis
What is the horizontal axis that passes through both right and left condyles called?
terminal hinge axis
transverse hinge axis
horizontal hinge axis
What movement of the mandible only occurs when in CR?
rotation in the sagittal plane around a horizontal axis
What movement causes rotation in the horizontal plane around the frontal axis?
lateral movement
What does the working side and non working side do during rotation in the horizontal plane around the frontal axis?
working side - frontal axis is in it
nonworking side - medially in the horizontal plane
What movement causes rotation in the vertical plane around the sagittal axis?
lateral movement
What does the working side and non working side do during rotation in the vertical plane around the sagittal axis?
working side - sagittal axis is in it
nonworking side - inferiorly in the frontal plane
What is the rotational center of the condyle?
where all three axes (horizontal, vertical, sagittal) meet
What is translation?
Defined as every point in an object
(mandible) simultaneously moving in the same direction with the same velocity
What movements cause translation?
- depression of the mandible
- protrusion
- lateral movement
In lateral movement with translation what do the working and nonworking condyles do?
working - shift laterally (bennett movement)
nonworking - moves down, forward, and medial
What is the bennet movement?
the lateral movement of the working side condyle in translation movements
During a lateral movement, this is the condyle on the side towards which the mandible moves is the…
working side condyle
- rotating
During a lateral movement, this is the condyle on the side opposite to which the mandible moves…
non-working side condyle
- orbiting
Working side condyle mainly rotates around a _______ axis
vertical
Non-working side condyle moves ________ ________ ________ through a series of rotations
downwards, forwards and medially
What is the condylar angle?
Angle at which the condyle moves away from a horizontal reference plane
How can you measure the condylar angle?
recorded via protrusive movement or lateral movements
During PROTRUSIVE MOVEMENT, the angle is influenced by the…
posterior slope of the articular eminence
What is fischer’s angle?
The angle formed by the intersection of the protrusive and non-working condylar paths as viewed in the sagittal plane.
What is the difference between the condylar angle recorded with a protrusive and lateral recor?
fischer’s angle (5-10 degrees)
What is bennett angle?
The angle at which the NWS condyle moves medially away from a sagittal reference plane as viewed in the horizontal plane during a lateral movement