The Human Body is an amazing mechanism! And the human hand is an extremely versatile tool, capable of delicate manipulations as well as powerful gripping actions. The arrangement of its 27 small bones, moved by 37 skeletal muscles that are connected to the bones by tendons, allows a wide range of movements and differentiates us from other primates! In particular, it is our ability to bring the tips of our thumbs and fingers together (known as a pincer grip), that gives human hand its unique dexterity.
Eyewitness Visual Dictionaries: The Visual Dictionary of the Human Body
To learn about the hand tendons and how they work, we made this super fun human hand DIY.
First, I outlined Adrian's hand and traced it on a piece of paper, so that I can measure the length of his fingers to cut the straws accordingly.
I then offered Adrian to insert the pipe-cleaner through each straw.
We also knotted a red bead at the end of each pipe cleaner so that the pipe cleaner would not slide through once pulled on.
A fun experiment: try raising your ring finger with your hand in a position shown on the above picture. The ring finger is stuck because it is joined to the same tendon as the middle finger. First Human Body Encyclopedia (DK First Reference).
Tendons are tissues that connect forearm muscles, which move fingers and thumbs, to the bone. Long tendons extend from these muscles through the wrist and attach to the small bones of the fingers and thumbs. The flexor tendons are located on the palm-side of the fingers and attach the flexor muscles to the finger bones, enabling the finger to be flexed into the palm for grasping and gripping. The extensor tendons (the DIY we made) are on the top side of fingers and help the digits to straighten, grasp and let go of objects. I have seen many videos on Instagram and Youtube of extensor tendons flexing fingers upwards (moving them towards the wrist), which is an unnatural movement since tendons on the top of the hand straighten the fingers, not flex them!
The flexor tendons, on the other hand, are located on the palm-side of the fingers, and allow you to bend your fingers. When muscles contract, tendons pull on bones. This causes parts of the body (such as a finger) to move. Each finger may flex and extend, abduct and adduct, and so also circumduct. Flexion is by far the strongest movement. To make flexor tendons DIY, simply tape the straws under the white paper cut out.
Adrian had a lot of fun learning about the human body and how the hand and tendons work. Books, visual DIYs and the process of learning and figuring out how to make hands-on models had proven the most efficient way of absorbing the information for us! Which way does your child learn best? Leave a comment! I love hearing from you!
For more anatomy inspired activities, see here our entire 💉Human BODY Anatomy Unit Study.