4. Mechanics of Mandibular Movement (2024)

FAQs

What are the 4 movements of the mandible? ›

[6] There are primarily 6 types of mandibular movement, including opening, closing, rightward jaw translation, leftward jaw translation, protrusion, and retrusion. Variability in jaw movement allows for mastication of different textures and consistencies.

During biting and the powerstroke of mastication, a combination of sagittal bending, corpus rotation, and transverse bending occurs. The result is a complex pattern of stresses and strains (compressive, tensile, shear, torsional) in the mandible.

Movements. A variety of movements occur at the TMJ. These movements are mandibular depression, elevation, lateral deviation (which occurs to both the right and left sides), retrusion and protrusion.

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. The axis of rotation for each plane will be described and illustrated.

mandibular movements such as the gliding of the occlusal surfaces of the dental arches against each other, either just in contact or in full occlusion, possibly with interposition of a thin layer of food. In other words, these are movements which could be selectively performed as well laterally and sagit- tally.

The unilateral contraction of the lateral pterygoid muscle with the ipsilateral medial pterygoid muscle results in lateral mandibular movement to the contralateral side. This movement is observable during functional and parafunctional lateral excursive movements, i.e., during chewing stroke, masticating, and clenching.

The human temporomandibular joint, is a ginglymo-arthrodial joint. The articular disk serves as a fibrous, viscoelastic structure that allows force distribution and smooth movement of the joint in its normal arrangement during mandibular movements.

The TMJ, therefore, is called a ginglymoarthroidal joint. Mandibular opening is initiated by action of the suprahyoid muscles. Simple rotation of the mandibular condyle in the glenoid fossa accounts for the first 25 mm of interincisal opening.

During normal movements, rotation and translation occur simultaneously, as the mandible rotates in one or more axes, each of the axes is changing orientation in space [16]. The total movement of the mandible does not consist only of rotation and translation.

Mandibular opening and closing movements while maintaining a retruded mandibular position create simple rotation around an imaginary axis. This rotation axis is called the hinge axis. The sagittal mandibular movement pathway converges at a point around the condylar head and makes a simple curve.

What is the Bennett movement of the mandible? ›

The Bennett movement is part of this group of movements (^2–3). It is a complex lateral movement or lateral shift of the mandible resulting from the movements of the condyles along the lateral inclines of the mandibular fossae during lateral jaw movement.

Starting from the closed position, a typical motion of the mandible can be summarized as follows: Both condyles begin the opening immediately downward and forward. Early in the closing stroke, the entire mandible moves laterally.

Special Movements

Protraction is the anterior movement of a bone in the horizontal plane. Retraction occurs as a joint moves back into position after protraction. Protraction and retraction can be seen in the movement of the mandible as the jaw is thrust outwards and then back inwards.

Relaxed jaw exercise is one of the best exercises for pain relief for the temporomandibular joint (TMJ). This exercise involves gently and slowly opening and closing your mouth while keeping your teeth apart and tongue on the roof of your mouth, allowing the jaw to relax.