Ask Me Everything5

Why are your hands so handy?

Your hands can make morę complex movements than the paws, claws, or hands of any other animal. 2 This is because the opposable thumb can move | across (oppose) the palm to touch the tips of the Ę other fingers and allow the hands to form different I grips. This means that humans can perform an array | of tasks, from throwing a spear, to typing a text | message, or drawing a landscape.

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How to: pick up a pencil

01 ■ Useupperarm muscles (tńceps brach ii not shown) to extend your arm and, therefore, your hand toward the pencil.

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---Use your flexor

irpi radialis and flexor irpi ulnaris muscles to ind your wrist as you ove your hand.

03 ■ With your hand

in position over the pencil, instruct your fiexor digitorum superficialis muscles to bend your fingers so that your fingertips touch the pencil.

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The body’s framework

■ Skeleton

The bones of the skeleton make up a supportive but flexible framework for the body and protect delicate internal organs.

■ Joints

Joints are points of connections between bones in the body. Many of them allow movement.

■ Muscles

Cords of tough tissue called tendons connect skeletal muscles to bones. Your nervous system instructs muscles to contract to move the bones so you can perform a rangę of movement:

Get a grip

The hand has two basie grips:

Power

Fingers flex to form a clamp against the palm. This grip uses mainly strong muscles in the forearm.

Usethumb

muscles to move it toward your fingers and touch the other side of the pencil to the fingers, creating a precision grip.

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■ Precision

05 ■ Finally,

straighten the wrist and use your upper arm muscles to bend your arm. This will raise your hand and lift the pencil.

The item is held between the thumb and fingertips. This grip mainly uses special muscles in the hands that move the thumb and fingers.