Tendons connect muscles to bones. They are tough bands of dense connective tissue that transmit the force of a contracting muscle to the skeleton, allowing joints and limbs to move.
Most tendons are rich in collagen fibers arranged to withstand pulling forces. When a muscle shortens, its tendon transfers that tension across a joint, causing the attached bone to move. Tendons can also help stabilize joints and store a small amount of elastic energy during activities such as running and jumping.
A tendon is often confused with a ligament because both contain collagen and support the musculoskeletal system. The distinction is simple: tendons connect muscle to bone, whereas ligaments connect bone to bone. Cartilage is a different type of connective tissue that cushions joints and helps shape structures such as the nose and ear.
The Achilles tendon is a familiar example. It connects the calf muscles to the heel bone and helps produce powerful movements such as walking, running, and jumping. Repetitive strain or sudden overload can cause tendinitis or a partial or complete tendon tear.