A tendon is a tough cord of fibrous tissue that connects muscles to bones. All muscles have origin and insertion points, where tendons attach the muscles to bones.
Tendons are composed of parallel collagen fibers that are non-elastic. When a muscle relaxes or contracts, the force is transmitted to a tendon. In turn, the tendon transmits that force to the connected bone, facilitating movement.
Pain may develop at a tendon from inflammation due to chronic overuse or injury. Due to their limited blood supply, injured tendons heal slowly.