Podcast
Questions and Answers
What type of mandibular movement is referred to as a hinge movement?
What type of mandibular movement is referred to as a hinge movement?
Which axis corresponds to the horizontal plane in mandibular movements?
Which axis corresponds to the horizontal plane in mandibular movements?
What occurs during the initial phase of the opening motion of the mandible?
What occurs during the initial phase of the opening motion of the mandible?
How far can the mandible move through pure rotational movements before gliding occurs?
How far can the mandible move through pure rotational movements before gliding occurs?
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What type of mandibular movement is described as moving forwards?
What type of mandibular movement is described as moving forwards?
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Which plane is also known as a side view?
Which plane is also known as a side view?
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Which of the following describes the main motion of the mandible during opening?
Which of the following describes the main motion of the mandible during opening?
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In which direction does the condyles move during protrusive movement?
In which direction does the condyles move during protrusive movement?
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Which axis is best described by facing the patient?
Which axis is best described by facing the patient?
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What is a result of simultaneous rotation and translation of the mandible?
What is a result of simultaneous rotation and translation of the mandible?
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What muscles are responsible for protrusive movements of the mandible?
What muscles are responsible for protrusive movements of the mandible?
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What is the incisal guidance in mandibular movements?
What is the incisal guidance in mandibular movements?
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What is the range of the protrusive condylar path in degrees?
What is the range of the protrusive condylar path in degrees?
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Which muscles are involved in the reverse direction of protrusive movements?
Which muscles are involved in the reverse direction of protrusive movements?
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In lateral movements, which side is referred to as the working side?
In lateral movements, which side is referred to as the working side?
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What is the function of the non-working (orbiting) condyle during lateral movement?
What is the function of the non-working (orbiting) condyle during lateral movement?
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What is the importance of studying mandibular movements?
What is the importance of studying mandibular movements?
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What angle is associated with the lateral condylar movement?
What angle is associated with the lateral condylar movement?
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Which of the following best describes the Bennett shift during mandibular lateral movement?
Which of the following best describes the Bennett shift during mandibular lateral movement?
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Which of the following is NOT a purpose of understanding mandibular movements?
Which of the following is NOT a purpose of understanding mandibular movements?
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Study Notes
Mandibular Movements - Part 2
- Mandibular movements are complex, involving both rotation and translation.
- Simultaneous rotation and translation around multiple axes result in intricate movements.
Mandibular Movement Types
- Protrusion: Assisted by lateral and medial pterygoid muscles.
- Retraction: Posterior temporalis fibers, deep masseter, geniohyoid, and digastric muscles.
- Elevation: Temporalis, masseter, and medial pterygoid.
- Depression: Gravity, digastric, geniohyoid, and mylohyoid muscles.
Reference Planes
- Sagittal plane: Side view
- Frontal plane: Facing the patient
- Horizontal plane: Parallel to the occlusal plane or floor
Axes of Rotation/Centers of Rotation
- Axes are imaginary lines, around which rotations occur.
- Movement around the horizontal axis is hinge motion (opening and closing).
- Movements around the frontal and sagittal axes are rotational.
Basic Mandibular Movements
- Classified by direction: opening/closing, forwards/protrusive, backwards/retrusive, sideways/lateral.
1- Opening and Closing (Depression and Elevation)
- Starts at rest, moves to maximum opening.
- Initial movement is rotation in the lower TMJ compartment.
- Pure rotation (10-20mm) followed by a gliding movement in the upper compartment.
- Reverse movement brings the mandible back to rest.
2- Forward (Protrusive Movement)
- Condyles move downward and forward.
- This movement follows the glenoid fossa and articular eminence.
- Protrusion involves contraction of external pterygoid muscles on both sides.
- Christensen Phenomenon: Posterior teeth separate as the mandibular moves forward.
- Incisal guidance is the path performed by the incisal point from the intercuspal position to edge positions.
2- Forward (Protrusive Movement) - Condylar Path
- Sagittal condylar path varies (30-40 degrees) between individuals.
3- Backward (Retrusive Movement)
- Reverse direction of protrusive movement.
- Temporalis muscles contract, moving mandible upward and backward.
4- Lateral Movement (Sideways)
- Right and left lateral movements are asymmetric.
- The working side condyle rotates, with slight bodily lateral translation.
- The non-working side condyle moves forward, downward, and medially.
- The Bennett angle (about 15°) is the angle of the non-working side condyle's medial movement.
Importance of Studying Mandibular Movements
- Designing, selecting, and adjusting articulators.
- Developing tooth forms for dental restorations.
- Diagnosing and treating TMJ disorders.
- Understanding the fundamental principles of occlusion.
- Properly selecting teeth.
- Arranging artificial teeth.
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Description
Explore the complexities of mandibular movements involving rotation and translation. This quiz delves into types of movements like protrusion and retraction, as well as reference planes and axes of rotation. Test your understanding of the intricate motions involved in jaw function.
