Most muscles are attached to bones by connecting tendons. Tendons are thick, tough cords of tissue that firmly attach to both the muscle and the bone, connecting the two. A few muscles attach directly to the bone without a connecting tendon.
Tendons grow directly out of muscle fiber and connect to the outer layer of the associated bone. Many bones have lumps or protrusions where the tendon connects. This provides extra surface area for a secure join. Tendons are strong enough to withstand tension when muscles contract to move the bone. Each muscle attaches to two bones, and the push and pull of the muscle moves the bones in relationship to each other.