Temporalis Anterior Muscle and Mandibular Positioning

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Question:
JFV asks:
But I’m a bit concerned by the temporalis. As it’s a fan-shaped muscle, there are several groups of fibers. And depending on which group of fibers “fires” it could mean different things about the mandibular position? Isn’t there a risk of having the jaw too much forward without an objective way to notice it (posterior temporalis fibers firing)?

Answer:
Yes, I agree. Without objectively measuring and observing a patient’s physiologic mandibular positioning relative to their habitual opening and closing path it would be possible to either record a bite registration either too far forward or too far back.

This is a deep and profoundly insightful question that few dentists in this profession would even acknowledge since most do not measure, quantify or even concern themselves with when recording a bite. We know that temporalis muscle fibers assist in elevating the mandible, closing the jaws. We also know that the posterior fibers retrudes the mandible after protrusion. We know that the temporalis muscles is an antero-posterior positioning muscle of the mandible. We know that strained temporalis muscles retract or retrude the mandible posteriorly and often in this posterior position TMD patients experience temporal headaches and pain.

It becomes obvious that temporal headaches, pain and tender temporal muscles would indicate something is wrong – pathologic and even more the mandible is functioning (open and closing of the jaw) in a habitual or accommodated retrusive manner that causes tight strained muscles. If the muscles are striaining like this it should be intuitive for any clinician to realize that recording a bite registration for the lab to accurately and precisely fabricate an intra oral occlusal appliance would require that the dentist help the patient relax these spastic posturing muscles first in order to avoid capturing a retracted mandibular to maxillary bite relationship.

If the dentist relaxes the muscles the mandible will not retract posterior, but in fact would shift anterior just enough so that it would open and close along an isotonic path of jaw closure. This isotonic path can be identified, located and recorded best when the doctor uses measuring devices that allows one to accurately and precisely see and document  these fine millimeter changes from a posterior position to a more normalized isotonic position…not a strained anteriorized (forced forward or forced backward) position.

In my experience low frequency involuntary TENS pulse allows the strained temporalis muscles to relax, thus releasing the retracting fibers,  allowing the mandible to relax naturally forward toward its isotonic position (obvserved using computerized mandibular scanning (CMS – jaw tracking) in real time combined with the TENS pulse).

With the involuntary TENS pulse one is also able to see the quality…. yes the “quality” and pattern of that pulse pattern (like an EKG heart monitor) to distinguish whether that pulse pattern truly represents an isotonic path of mandibular closure, or a too far forward position or a retracted retruded mandibular position. The involuntary TENs pulse can be recorded and monitored with K7 jaw tracking instrumentation precisely and accurately allowing the dentist to identify the most optimal mandibular position.

This is how we train our OC doctors to recognize whether their patients bite registrations are optimized in the correct position or not. Guessing is not acceptable when tenths of millimeters matter with mandibular positioning and temporal muscle fibers.

Small things matter!

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Temporalis Anterior Muscle and Mandibular Positioning