Un­der the skin of the hands, you will find the body’s most so­phis­ti­cated net­work of bones and joints.

Science Illustrated - - CONTENTS -

Do colours in­flu­ence our mood and do all flies lay on their backs when they die?

A hand is a fine-tuned grip­ping de­vice and an im­por­tant sen­sory or­gan made up of a clever sys­tem of un­bro­ken bones, mus­cles, joints, lig­a­ments, ten­dons, nerves, and blood ves­sels. The bones and mus­cles co­op­er­ate to pro­vide the hand with strength, the joints en­sure mo­bil­ity, and the nerves are re­spon­si­ble for the sense of touch. The pow­er­ful fore­arm mus­cles bend fin­gers and wrists by pulling at the bones of the hand via long, slim ten­dons. The hand it­self con­tains a num­ber of small mus­cles, which in com­plex in­ter­ac­tion take care of the fin­gers’ ul­tra­fine pre­ci­sion mo­tions such as con­trol­ling the di­rec­tion of a pen or thread­ing a nee­dle.

The hand it­self con­sists of the car­pus, the metacar­pus, and the fin­gers. The car­pus is a mo­saic of eight bones lo­cated in two rows that are closely linked by tight lig­a­ments. One bone for ev­ery fin­ger make up the metacar­pus. The thumb's metacarpal bone is shorter than that of the four other fin­gers, but much more flex­i­ble in the ba­sic joint. This en­sures that the thumb can be moved in front of the palm of the hand, al­low­ing the hand to grip a tool, rope, etc.

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