The purpose of this study is to obtain the more accurate and quantitative knowledge as to how the normal hand works.
The author took 8mm motion picture of about 90 kinds of activities of daily living.
Each hand work is composed of series of minimal unit of hand action. This minimal unit is considered as a certain interrelationship between the hand and object. The author graded this interrelationship from the simplest to the most complicated, which are Detach, Touch, Push, Hook, Constrain, Fixation (Pinch and Grip), dynamic patterns and combined patterns.
From the motion film, the author investigated firstly, the frequency of each pattern of hand use, secondly, the importance of each finger joint and thirdly, the used part of hand.
It was evident that dominant hand was involved in more complicated patterns such as pinch, grip or dynamic patterns and that metacarpophalangeal and proximal interphalangeal joint of radial three fingers were outstandingly important.
On the other hand, in the non-dominant hand, simpler patterns such as push had relatively more frequency than in dominant hand and the more radial and the more proximal finger joints had the more importance.
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