In which of the following compartments of temporomandibular joint do the rotatory movements of the jaw take place?
Joint space above the articular disc
Joint space below the articular disc
Both a and b
Types of Movements
- Two types of movements occur in the temporomandibular joint: rotational and translational.
- Dorland’s Medical Dictionary defines rotation as “the process of turning around an axis: movement of a body about its axis.”
- In the masticatory system, rotation occurs when the mouth opens and closes around a fixed point or axis within the condyles.
- In other words, the teeth can be separated and then occluded with no positional change of the condyles.
- In the TMJ, rotation occurs as movement within the inferior cavity of the joint.
- It is thus movement between the superior surface of the condyle and the inferior surface of the articular disc.
- Rotational movement of the mandible can occur in all three reference planes: horizontal, frontal (vertical), and sagittal. In each plane it occurs around a point called the axis.
- Translation can be defined as a movement in which every point of the moving object simultaneously has the same direction and velocity.
- In the masticatory system, it occurs when the mandible moves forward, as in protrusion.
- The teeth, condyles, and rami all move in the same direction and to the same degree.