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He crack his fingers?
A long time science could not give a clear answer — why some people crunching fingers, and how it can be summoned. Thing, seemingly insignificant, but a snap of the fingers could not unravel medical scientists. Each of us, if he did not crunches, then at least observed it in others no time. Some people it's quite unnerving. Interestingly, in ancient times, the inhabitants of the middle East was made to crunch your fingers in a sign of mourning for the dead. However, those people who mourned for real, such as, for example, a widow could not do it and they had to hire mourners.
After a series of studies by British scientist still managed reason for the snap of the fingers. At first glance, seems to crackle there's absolutely nothing, because the joint inside is smooth. Therefore, researchers have developed a special device which pulled the finger at a certain speed and strength. For the experiment, invited volunteers, and during the stretching fingers of the experimental was carried out radiography of joints.
As it turned out, in the cavity with a special lubricating fluid during stretching of the joint is dramatically reduced pressure. Due to a drop in pressure is "boiling" of the liquid and there is formed the gas bubble. However, due to the tightness of the joint, the gas has nowhere to go after the end thrust gas immediately dissolves again in the liquid, and the bubble collapses with a characteristic loud sound. And the grieving widows of the ancient East could not crack because at the time of stress a person always observed an increased amount of fluid in the joint cavity, so that the pressure drop in it may not be so strong. The answer to the question, is harmful or, on the contrary, it is useful to scrunch with your fingers, is still there.
Source: /users/448
After a series of studies by British scientist still managed reason for the snap of the fingers. At first glance, seems to crackle there's absolutely nothing, because the joint inside is smooth. Therefore, researchers have developed a special device which pulled the finger at a certain speed and strength. For the experiment, invited volunteers, and during the stretching fingers of the experimental was carried out radiography of joints.
As it turned out, in the cavity with a special lubricating fluid during stretching of the joint is dramatically reduced pressure. Due to a drop in pressure is "boiling" of the liquid and there is formed the gas bubble. However, due to the tightness of the joint, the gas has nowhere to go after the end thrust gas immediately dissolves again in the liquid, and the bubble collapses with a characteristic loud sound. And the grieving widows of the ancient East could not crack because at the time of stress a person always observed an increased amount of fluid in the joint cavity, so that the pressure drop in it may not be so strong. The answer to the question, is harmful or, on the contrary, it is useful to scrunch with your fingers, is still there.
Source: /users/448