ABSTRACT
Electromyographic studies conducted over the past 45 years have revealed much about the function of the craniomandibular muscles. The application of intramuscular electrodes in multiple muscles has provided insight into the function of each of the jaw-closing and jaw opening muscles, with surface electromyography primarily providing an analysis of the two superficial muscles, the temporalis and masseter. The primary mode of assessing cranio mandibular muscle function with electromyography has been in the presence and amplitude of the muscle activity so that the greater the EMG activity, the more the muscle is inferred to be recruited. The EMG activity does not usually indicate the force developed by the muscle, as the mechanical advantage and direction of force vectors will be additional parameters de termining the level and timing of muscle activity. However, the EMG activity indicates which muscle is most activated by the central nervous system, and the levels of EMG activity suggest, indirectly, that the muscle has a direct role in a particular function.
