Activity Title: Make an articulated hand (with cool movable fingers)
Learn all about how tendons work in this simple science experiment!
How do we do it?
1. Trace each hand on a piece of craft foam and then cut out the shape.
2. Draw finger nails on the hand (to make it fun, you can add nail polish to the nails!)
3. Cut paper straws into small pieces, and stick them on the hand and fingers to represent the bones and the tendon sheaths that are attached to them. (Leave gaps between each piece, as this will allow the fingers to bend.)
4. Tie beads to five pieces of twine (or yarn). Thread each piece of yarn through the straws on the finger and thumb, into the corresponding straws in the hand.
5. To prevent the twine from falling out, tie a further five beads to the other ends of the twine.
6. Tape a chopstick to the palm to act as a handle - This makes it much easier to be able to hold and manipulate the hand.
7. Your artificial hand is ready – pull the strings to more the fingers up and down. Cool isn’t it?
What is the science behind it?
There are 3 bones in each finger while the thumb has 2 bones. These bones are called phalanges. The phalanges connect to 5 bones in the main part of your hand, called metacarpals. The muscles that move your fingers and thumb are in your forearm. Long flexor tendons extend from these forearm muscles through your wrist and palm to your fingers and thumb. The tendons slide though a snug tunnel, called the tendon sheath, which is attached to the little bones in your fingers and thumb and keep the tendons in place. When the muscles in the forearm contract, they pull on these tendons to move the bones.
The straws in the activity represent these tendon sheaths, and the twine represents the tendons.