A fist is the shape of a hand when the fingers are bent inward against the palm and held there tightly. To make or clench a fist is to fold the fingers tightly into the center of the palm and then to clamp the thumb over the middle phalanges; in contrast to this "closed" fist, one keeps the fist "open" by holding the thumb against the side of the index finger. One uses the closed fist to punch the lower phalanges against a surface, or to pound with the little-finger side of the hand's heel; one uses the open fist to knock with the middle knuckle of the middle finger.
Making a fist is virtually unknown among other primates. This is because while "most primate hands are long of palm and finger [and] short of thumb", the proportions are the opposite for humans.
At least one study has claimed that the clenching of one's fist can be used to recall information.
Some studies have shown that making fists can help humans to cope with stress or anxiety because the mind gets preoccupied with the tightening of the muscle to focus on the issue at hand.
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In this gallery "Fist" we have 18 free PNG images with transparent background.