A tendon connects a muscle to a bone in the human body.
When a skeletal muscle contracts, its tendon transmits the resulting pulling force to a bone, producing movement at a joint. Tendons are made primarily of dense, regularly arranged collagen fibres, which give them high tensile strength. Their fibres are aligned along the direction of force rather than arranged randomly.
Tendons are often confused with ligaments. A ligament connects bone to bone and helps stabilize a joint, whereas a tendon connects muscle to bone. Cartilage is a different connective tissue that can provide smooth joint surfaces, structural support, or flexible shape.
Some tendons run through protective sheaths or glide beside small fluid-filled bursae that reduce friction. The Achilles tendon, which connects calf muscles to the heel bone, is one of the best-known tendons and is especially important for walking, running, and jumping.