On the Mechanical Work Done by the Movement of the Human Lower Jaw in Various Actions Except the Masticatory

Kimura, reported on the mechanical work done by the masticatory movement of the human lower jaw. But in daily life, besides the mastication the lower jaw performes various movements, for example talking, drinking, smoking and others. From the physiological viewpoint it is by no means meaningless to make clear the work value done, in these actions. Thus the present work was carried out to measure such work value. The method is almost the same as in Kimura's previous experiment. The principle is: Resolving the movement of the lower jaw into the three rectangular directions, the total sum of which is indicated on the scale of the apparatus, thus the work done during the movement being indicated as the product of the total distance on the scale and the sum of the two weights-one connected to the lower jaw and moved with its movement and the weight of the lowerr jaw itself. (ca. 100 g.) The persons used for the experiment are 11 men and 6 women, each of whom has normal bite. The measuring of the work was done by makingg the person to do a certain definite amount of the action — speaking, drinking, smoking and others. The experimental results are: (1) There were considerably large differences between the work values for the same kind of action according to the difference of the individual. (2) The mean values through all persons used for the experiment are 9.19 g-m.in pronuncing A, B, C, …, Z; 11.01g-m. in pronuncing i (_??_), ro (_??_), ha (_??_), …, n (_??_) ; 11.18g-m. in pronuncillg, a (_??_), i (_??_), u (_??_), e (_??_), o (_??_), …, n (_??_) ; 6.05g-m in singing a children's song; 127.59 g-m. in tasting a piece of candy; 8.81 g-m. in drinking a cup of tea; and 14.67 g-m. in smoking a whole piece of cigarette. (3) The total amount of these work performed during a day in ordinary life of a man, becomes as large as 4000 g-m. The amount of the work is considered by no means negligible as in the case of discussing the calorie expenditure of a man.