Mandibular Movement Flashcards
(31 cards)
What are the four anatomic determinants of mandibular movement?
- right TMJ
- left TMJ
- Teeth/occlusion
- Neuromusculature
Aspects of mandibular movement:
-complex
-Three-dimensional
-takes time and effort to understand
What are the two different types of movements within the TMJ?
- rotational movement (inferior joint compartment)
- translational movement (superior joint compartment)
Where does rotational movement within TMJ occur?
within the inferior joint compartment (on the articular disk)
–condyle rotates on the inferior aspect of the articular disk
Where does translational movement within TMJ occur?
(superior joint compartment)
What is rotation within the TMJ? When does it occur?
- process of turning about the axis
- mouth opens and closes around a fixed point or axis within the condyles
How far (mm) does rotation occur before translation begins?
20-25 mm of opening
What are the three reference planes that rotational movements of mandible may occur in?
sagittal plane - around horizontal axis
horizontal plane - around vertical axis
frontal plane - around 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
only rotational movement that can be isolated clinically
Rotation in the sagittal plane around a horizontal 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 (& forward) in the horizontal plane oribiting around this frontal axis
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 around the sagittal axis
What is the rotational center of the condyle?
where all three axes (horizontal, vertical, sagittal) meet
Defined as every point in an object
(mandible) simultaneously moving in the same direction with the same velocity
What is translation?
What movements cause translation?
- depression of the mandible (25mm+)
- 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
(Lateral movement of the mandible) Working side condyle mainly rotates around a _______ axis
vertical/frontal
(Lateral movement of the mandible) Non-working side condyle moves ________ ________ ________ through a series of rotations
downwards, forwards and medially
(moves over the steeper medial wall of the articular fossa)
