eli5 Why does the hand automatically rest in a „claw“ position

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If I’m resting somewhere and my hand is laying on its back the hands automatically form a claw if not manually corrected to lying flat. Why is this? Why isn’t it automatically flat?

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4 Answers

Anonymous 0 Comments

Because the default state of muscles is relaxed. To open your hand you have to contract the muscles in your hand and arm. The default position of your hand is “the claw” because that’s the state your hand is in with the muscles relaxed.

It’s the same reason a persons eyes will open when they die. You have to exert muscles to close your eyes.

Anonymous 0 Comments

“Flat” is with the muscles that straighten the fingers at maximum contraction, not their rest state.

Since the “make a fist” grip muscles are vastly stronger they tend to dominate when neither one is asked to do any work and pull you into that claw.

Anonymous 0 Comments

There are two states of muscle contraction, flexion and extension. There are tendons that connect your muscles to your bones and joints that pull on them to make this happen. Your bones and joints are constantly being pulled on both sides from the muscles and tendons. The default position that forms from this comes from the balance that forms where one side and the other are being pulled the same amount.

The muscles that make a fist are stronger than the muscles that make your hand flat, so your hand is pulled more that way until it balances out.

Anonymous 0 Comments

Your muscles are not just like cables. They are more like rubber bands! They are in constant tension and then cause you to move when they contract. Do this little experiment on yourself:

Put your elbow on a table with your arm in the air. Allow your hand to relax, let your hand fall down, palm toward your forearm. Now, let it fall the other way, back of your hand towards your forearm. Did your fingers naturally contract a little when you did this? Did the “claw” get tighter? You’re changing the length of the muscles in resting tension!

You can use this test to determine if someone has a tendon injury, like from a puncture in their palm. If the finger doesn’t contract when brought from palm down to palm up like the rest of them, the tendon is probably severed!

Source: am orthopaedic surgeon.