Mandibular electromyograph

Abstract

A system for measuring and displaying the coordination, duration of and interval between contractions of the masticatory muscles. Several electrodes, each associated with a masticatory muscle, generate signals responsive to muscle contraction. The electrode outputs are amplified, rectified and filtered, and then applied to several circuits, depending upon the operating mode selected. In a first mode, the filtered outputs are integrated during each muscle contraction and displayed by an electronic bar graph. The output is also applied to a threshold circuit which identifies the start and finish of the muscle contraction. The output of the threshold circuit is then processed by a timing circuit which determines and displays in digital form the duration of the muscle contraction and the interval between contractions. The system operates in a second mode in the same manner as in the first mode, except that an analog signal is derived from the digitized interval signal and applied to the bar graph in place of the integrated output. In a third mode, the filtered output is applied to a logarithmic amplifier which drives the bar graph so that the logarithm of the electrode voltage amplitude is displayed. The output of the threshold circuit is also processed by a second timing circuit which determines and displays in digital form the time lapse between the contraction of the first muscle to contract and the contraction of the remaining muscles, thereby providing an indication of muscle coordination.