Our bodies have different types of tissues that are used to connect all of our different parts. Bones are connected to other bones by special tissues called "ligaments." But when bones are connected to muscles, the special tissues are called "tendons."
Tendons are very strong. They are built from long strands of protein and they are not very stretchy. When a muscle pulls, they pull too and they can move our bones.
We have tendons in many parts of our bodies: wrists, elbows, thumbs, shoulders, knees, head, legs, and heels. Tendons almost always connect bone to muscle, but sometimes they connect muscle to other things, like an eyeball!