Make a model of your hand that really works!

House of science experiment - see how fingers and thumbs move. Photo/supplied

Make a model hand to learn about muscles and tendons We're finding out all about the fantastic human body at the House of Science this term, and today we're going to make a model hand to understand how our fingers and thumbs work.

Fingers and thumbs (also known as digits) are always busy, helping us to hold, grip, touch, grasp, stretch, enclose, squeeze and feel. Like all actions performed by the body, it's our muscles that do the hard work, yet our fingers and thumbs don't have any muscles inside them at all.

Why? The muscles which power all those hand actions are located in our forearms and palms and they are connected to our finger bones by strings, known as tendons.

What you need:
* A piece of flexible card about the size of your hand
* A pen or pencil
* Scissors
* String and stapler

What to do:
1.Take the piece of card and trace the outline of your hand with a pen or pencil.
2. Cut outthe shape of your hand with scissors.
3. Cut the string into 5 pieces that are about the length of your hand.
4.Tie a piece of string to the tip of each finger and thumb and stretch itto the base ofthe palm. Staple the string to the card at the same points where you have joints in your fingers and thumb. The strings should be able to pull through the staples.
5.Try pulling the strings from the base of the palm. What happens?

What's happening?
Our muscular system powers every movement we make, from a simple smile to lifting a heavy box. In the case of our fingers and thumbs, there are two main sets of muscles which connect to our digits via tendons. Flexor muscles - on the underside of the forearm - pull on the tendons to bend our fingers and thumb, and extensors - connected to the top of the forearm - release the tendons to straighten the fingers and thumb.

When you pull on the strings in your model, you can see how the fingers and thumb can move and curl.That's just what's happening with your real hand when the tendons pull he finger bones.

House of science experiment - creating this model hand can help explain how muscles and tendons work. Photo/supplied

Did you know?
* Each of our hands is made up of 27 bones.
* Each hand has 34 muscles, which move the fingers and thumb - 17 in the palm and 18 in the forearm; nine individual muscles control the thumb.
* The palm has unique fingerprints, has no hair and doesn't tan.
* Estimates suggest around 12.6 per cent of men and 9.9 per cent of women are left- anded.

Thanks to Science Kids for this activity, www.sciencekids.co.nz

* The House of Science Tauranga is a charitable trust which exists to connect and resource the local science community in order to celebrate the power and potential of Science. Contact Chris Duggan on 027 337 9342 or see www.houseofscience.org.nz for more information.