Human hands are delicate and efficient instruments. Each one contains 27 bones, one more than each human foot. Each also contains muscles and tendons which react to nerve stimuli. It is these reactions which enable people to clench and grasp. The thumbs are, perhaps, the most important part of each human hand. They are opposable, which gives them their unique movement. Besides humans, only apes have opposable thumbs. The ability to grasp is probably responsible for much of human progress.

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Human hands are delicate and efficient instruments. Each one contains 27 bones, one more than each human foot. Each also contains muscles and tendons which react to nerve stimuli. The thumbs are, perhaps, the most important part of each human hand. The ability to grasp is probably responsible for much of human progress.