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Parafunctional Clenching Potential of the Temporalis |
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| Following the translation(s) of the condyle(s), the temporalis' role is to elevate the mandible, with the intent of grasping/biting the object/food that has been positioned between the teeth. The occluding of the teeth is the LPs signal to re-open the mandible. However, in the event the temporalis contraction(s) persist, re-opening may not be possible, depending on the intensity of the continuing temporalis activity.
The example to the right demonstrates the clenching of the teeth by the temporalis (which during sleep can exceed the patients waking voluntary maximum effort). Once the teeth are occluded, the inferior LPs contract with the intent of translating the condyles, and the digastric contracts with the intent of depression the mandible but have no effect, while the digastric contacts with up to 2/3's its maximum, also having no effect. The condyles are being stabilized by the posterior bilateral clenching/occluding activity. The isometric contractions of the digastric has a particular result.
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The chart below shows recordings of LP activity during various voluntarily held jaw positions. The only time the inferior head of the LP is truely "silent" is during intentional retrusion (which can only follow protrusion). During maximum clenching, ILPs isometrically may contract at up to 50% of their maximum capacity, but provide no condylar movement/advancement, due to the posterior "stabilizing" of the clenching activity.
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