足踏の平衡生理

The aim of the present investigation is to obtain a better understanding on how the cervical and/or lumbar proprioceptors participate in a smooth performance of stepping. The investigation includes two series of examinations. Examination I: Ten normal subjects aged 18 to 39 were examined. To record movements of the head induced by stepping (Fukuda's method), we devised a new piece of equipment termed a drift meter. Using this equipment, movements of the head from side to side and/or back and forth can be recorded in terms of the angle of deviation of the head from the upright position of the head while standing on both feet.<br>Deviation of the head from side to side and/or back and forth is averaged using a computer. The averaged registrograms of deviation of the head thus obtained are analyzed in relation to the movements of the feet. The results obtained were as follows.<br>(1) There was a certain correlation between the movements of the head and those of the feet during stepping and, moreover, this correlation can be reasonably explained on the basis of the theory of the tonic neck reflex.<br>(2) A rebound phenomenon was elicited in the movements of the head during stepping. This phenomen is conductive to the reinforcement of the tonic neck reflex, through which a smooth performance of stepping can be realized.<br>(3) The results described in (1) and (2) were observed when the head deviated from side to side and/or back and forth.<br>Examination II: Ten normal subjects aged 26 to 39 were examined. The deviation of the head during stepping was measured after fixing the waist with a corset and the results thus obtained were compared with those of the deviation of the head without this corset. In addition, patterns of averaged resistrograms of movement of the head were compared under the following two conditions, i. e., stepping with a corset and that without this corset.<br>The recordings and the method of analysis of movements of the head and feet used herein were the same as those described in examination I.<br>The following results were obtained.<br>(1) The deviation of the head tended to increase when the subject's waist was fixed with a corset. This tendency was seen when the head deviated from side to side and/or back and forth. The above-mentioned phenomenon is considered to be a compensatory action of the cervical proprioceptors in response to the limitation of the activity of the lumbar proprioceptors.<br>(2) A similarity in patterns was found between the averaged registrograms of movements of the head in the above two conditions of stepping.<br>From the results of examinations I and II, we conclude the following:<br>(1) The cervical proprioceptors play a major role in the control of the muscle tone of the lower limbs during stepping and such control is realized through the tonic neck reflex.<br>(2) The lumbar proprioceptors are also responsible for smooth performance of stepping and the role of the lumbar proprioceptors in stepping is realized in close collaboration with the cervical proprioceptors.