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Spokane, Washington  Est. May 19, 1883
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Ask Dr. K: No muscles, but our fingers work well

Anthony L. Komaroff Universal Uclick

DEAR DOCTOR K: A friend told me that we have no muscles in our fingers. Is that true? If so, then how do our fingers do all that they do?

DEAR READER: It is true, but our hands work wonderfully anyway. That’s because even though there are no muscles in the fingers, 34 muscles in the palms and forearms make the fingers work.

Each hand has 27 bones and a corresponding number of joints (the spaces where two bones meet). Together, the bones in our hands make up nearly a quarter of the total number of bones in our body.

Of course, the muscles in our palms and forearms make the fingers work only when the brain tells them to. So many subtle and important things are done by our hands that about one-fourth of the part of the brain that controls body movement is devoted to controlling our hands.

So how do we hold a pot, open a door or play the piano? It begins in the brain, which sends messages down the nerves that connect to the muscles in our palms and forearms. Those messages tell specific muscles to tighten and others to relax. Three major nerves control the movements of our hands.

The muscles are all connected to tendons. Those tendons connect each muscle to specific bones in our fingers. Tendons are strong, connective tissue fibers. They are the things that finally move your fingers the way you want them to move.

When a muscle contracts, it pulls on the tendon, which then pulls on the bone and moves it.

You may have heard that an opposable thumb is a key anatomical difference between humans and animals. An opposable thumb means that the thumb can oppose, or touch, the index finger. Actually, many animals – chimpanzees, koalas, even opossums – have opposable thumbs.

However, it actually is our unique ability to also oppose our other fingers to the thumb – and to thereby strongly grip and grasp objects – that makes us special.

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