Ropes that tie muscle to bone
A tendon is a tough cord at the end of a muscle. One end blends into the muscle. The other end is anchored tight to a bone.
Muscles do the pulling, and tendons pass that pull along to the bone. It's like the rope you use to pull a wagon: you pull the rope, and the rope pulls the wagon.
Some tendons are short and fat. Others are long and thin, like the ones that reach all the way from your forearm to your fingertips.
What tendons are made of
Tendons are made mostly of collagen (KOL-uh-jen), a tough, stringy material your body makes. Your skin has collagen in it too.
The collagen strands line up side by side, like lots of strings twisted into a rope. That makes tendons super strong for their size.
Tendons are a little springy, too. When you run, some of them stretch and snap back like rubber bands, helping you bounce along.
Muscles look red, but tendons look shiny white.
Find your tendons
Try it: lift your fingers up and look at the back of your hand. See the cords moving under the skin? Those are tendons.
Now make a fist and bend your wrist toward you. Look at the inside of your wrist. More tendons!
Last, pinch gently just above the back of your heel. That thick cord is your Achilles tendon.
The Achilles tendon
Your Achilles (uh-KILL-eez) tendon ties your calf muscles to your heel bone. It's the thickest and strongest tendon in your body.
It's named after Achilles, a hero in an old Greek story. In the story, his mother dipped him in a magic river to protect him, but she held him by the heel. So his heel was his one weak spot.
That's where the saying 'Achilles heel' comes from. But in real life, your Achilles tendon isn't weak at all. It handles huge pulls every time you run and jump.
Tendons and ligaments are different
Ligaments are tough bands too, but they do a different job. They hold bone to bone at your joints, like straps holding a gate to its post.
Here's a way to remember: Tendons Tie muscle to bone. Ligaments Link bone to bone.
Slow healers
Tendons get less blood than muscles do. That means when a tendon gets hurt, it heals slowly.
That's why warming up, building up slowly and resting when something hurts are so important.