Ralph W. Stacy

Electromyographic analysis of jaw movements

P REVIOUS ARTICLES have reported the frequency response requirements encountered in dental electromyography and have outlined a practical means of obtaining electromyograms of jaw muscle activity under optimal conditions. The influence and inadequacy of a single electrode reference on electromyograms was demonstrated and the necessity for using the multielectrode or standard generalized reference was established.l*2 The impetus of electromyography has reached beyond the determination of simple muscle function or dysfunction into the areas of orthodontics, periodontics, prosthodontics, and oral surgery. The electromyographer must be cognizant of the limitations of his instrumentation, and the dental profession likewise must realize the limit of its usefulness. The objectives of this study were (1) to determine the range of variability of muscular activity in jaw movements for a group of patients, (2) to determine the range of variability in a series of electromyograms of one patient, (3) to provide electromyographic data obtained with high-fidelity techniques for future reference, and (4) to provide an analysis of the role played by the external pterygoid muscles in trained (learned) jaw movements. In order to accomplish these objectives, statistical techniques were employed to analyze data derived from the electromyograms.

Electromyographic studies of mandibular muscles in basic jaw movements

Abstract The muscular activity for various jaw movements has been measured and the total electrical activity of the different muscles compared on a time basis. Based on observed electrical activity and anatomic considerations, it has been concluded that the external pterygoid and suprahyoid muscles were primarily responsible for the uncontrolled opening movement. The masseter and temporal muscles, of those listed, were responsible for the closing movement. The internal pterygoid muscles were not tested. The left external pterygoid muscle was mainly responsible for the movement of the mandible to the right and the right external pterygoid muscle for the opposite movement. Both external pterygoid muscles were responsible for the protrusion of the mandible. The analysis and discussion of the material covering the different sets of dentures will be presented at a later time.

A mathematical analysis of carbon dioxide respiration in man

By means of physico-mathematical models, formulas are obtained for the purpose of making analyses of external carbon dioxide respiration in man under conditions of metabolic equilibrium. The methods evolved are flexible, permitting study of a wide variety of physiological assumptions. Sample calculations relate various factors in the process of external respiration, and show good agreement with experimental data. A quantitative description of the effects of various factors on rate of carbon dioxide output and alveolar tension is given. In particular, this theory gives a quantitative prediction of the fluctuation in alveolar carbon dioxide tension over the period of a single respiratory cycle.

A Mass Spectrometer for Continuous Gas Analysis

An instrument for recording continuously the relative abundance of gases in a three component mixture is described. High accuracy of analysis has been sacrificed in favor of high speed response since the instrument was designed primarily for use in the investigation of respiratory problems. An instantaneous change in gas composition will appear on the record with a lag of less than 0.2 second and will require approximately 0.1 second to settle on this new value.

Computer Analysis of Arterial Properties

Use of an analog computer for determination of mechanical properties of the arterial bed is described. This approach involves mathematical operations on a recorded central pulse to produce a computed peripheral pulse and computer parameters varied until matching is accomplished. Values for arterial elasticity, etc. are calculated from the computer settings.

A mathematical analysis of oxygen respiration in man

By means of physicomathematical models similar to those used by A. B. Chilton and R. W. Stacy (1952) formulas are obtained for the purpose of analyzing oxygen respiration in man under conditions of metabolic equilibrium. The formulas are applied to conditions involving a variety of physiological assumptions. Calculated quantities are shown to be in agreement with experimental values. A quantitative prediction is made of the fluctuation in alveolar oxygen tension over a single respiratory cycle. Finally, calculations are completed for all alveolar gases; and the over-all results are shown to be self-consistent to the degree expected in view of the simplifying approximations made.

Harmonic Analysis of Aortic Pressure Pulses in the Dog

Aortic pulse waves were recorded in dogs at the junctions of the left renal artery and the inferior mescntcric artery with the aorta, under normal conditions, after administration of norepincphriue and acetylcholine, and after manual blocking of the femoral arteries. These pulses (343) were subjected to Fourier analysis, and apparent phase velocities and foot-of-the-wave velocities were calculated. The results strongly indicate the presence of reflected waves, and it is shown that foot-of-the- wave velocities provide erroneous information. The arterial system is such that in the arteries per se, the reflected wave is a discrete and definable quantity; its origin can be shown to be an apparent site of reflection located in the peripheral one-third of the thighs of the dog.

DYNAMICS OF PRESSURE PULSE TRANSMISSION IN THE AORTA

Physical analysis of the arterial system has always been of primary interest to cardiovascular physiologists and clinicians. Ultimately, one would hope to be able to determine all significant physical parameters of this system; such efforts have been constrained by the lack of adequate approaches to detailed analysis of the systems. The delaying factors in detailed analysis have been the complexity of the system, the nonlinear nature of its components, and the lack of methods which reveal dynamic parameters. I t is important that the distributed system analysis of arterial dynamics be pursued, for in such analysis one finds true understanding of the relation between arterial wall stiffness and pulse wave velocity, of the relation of stroke volume to pulse pressure, and so on. These are factors of great significance in medicine; they are the factors which may be derived through the approaches described herein. The study described herein is based on the groundwork done by a number of researchers.’-’’ This paper describes the theoretical basis of a numerical analysis resulting in values for reflection coefficients and “true” phase velocities in the aorta, as well as experiments in which such analysis has been applied in the anesthetized dog.

Role of Abdominal Aortic Branches in Pulse Wave Contour Genesis

Central and peripheral pulse wave contours were recorded in dogs before and after occlusion of the major visceral arteries. Comparison of the pulse wave contours indicates that occlusion of the visceral branches produces very little effect upon the wave form of the central and peripheral pulse. The major changes noted were slight shifts in the timing of reflected components, and it would appear that the timing changes can be explained on the basis of the increase in pulse wave velocity attendant with a rise in the arterial blood pressure. Both the importance of these findings in the understanding of pulse wave contour genesis and the basic assumptions of the standing wave hypothesis are discussed.

Alveolar carbon dioxide equilibria in breath-holding experiments

An investigation was made of the equilibria approached by alveolar CO2 tension in normal human subjects during breath holding. A major objective of this work was to test the hypothesis that the approached equilibrium was with deoxygenated venous rather than with oxygenated venous blood. The study included determination of CO2 tension of expired air by continuous recording before and after breath holding for various time periods, with simultaneous airflow recordings. Pulmonary blood flows were calculated from these data, and were compared with those obtained by an independent rebreathing technique. The findings indicate that the equilibrium approached in the alveolar spaces during breath holding is between the alveolar air and the blood as it enters the pulmonary capillary. This would indicate that CO2 dumping by passive transfer must precede the uptake of oxygen. Effective pulmonary flows calculated from these data were reproducible and in agreement with those obtained by the rebreathing technique. human pulmonary blood flows; alveolar CO2 transport properties; CO2 rebreathing in humans Submitted on July 22, 1963