This is a really nice little model that demonstrates how tendons make our fingers move. Did you know that it’s the muscles in your forearm that move your fingers, via long tendons?

Instructions

To make the hand you will need:

• 5 drinking straws
• string or cotton
• sellotape
• A4 paper
• Scissors

Place your hand on the card, fingers spread out, and draw around it.

Take one drinking straw and cut three small pieces of the end. Roughly 1-2cm long depending on the length of your fingers. Lay these out on one of the fingers of the paper hand.

Line the straws up along the middle of the finger with a small gap in between them. Stick each one down with a small piece of sellotape.

Take the long piece of straw, line it up with the other pieces and stick it down in the palm of the hand. Cut the end at the wrist.

Carefully thread the string or cotton down the straws, from the top of the finger down to the wrist. Tie a knot at the top so that it doesn’t slide down the straw.

Leave the string long at the wrist end

Repeat for the other 4 fingers.

How Does It Work?

The muscles inside your forearm have long tendons running up through wrist to your fingers. These muscles allow you to flex your fingers, bending the tips towards your palm. When you pull the strings, you mimic the shortening of these tendons, and the fingers curl.

Look at your wrist and wriggle your fingers. You’ll see the tendons in your wrist move.

Add some tech

If you want to make a cooler, arduino-driven robot hand, then these lesson plans from Microsoft are well worth a look!