Tendons are components of skeletal muscle, consisting of dense connective tissue, and generally have no contractile capacity. Skeletal muscle including tendon and muscle belly two parts, tendon for the muscle end of the connective tissue fiber cord, tendon is tougher than the muscle and the volume is small, because it is mainly composed of parallel bundles of collagen fibers, so there is no contractile ability, the surface is covered with connective tissue membrane. The muscle belly is made up of muscle fibers, red in color and soft in texture, and has the ability to contract. Tendons can be damaged to varying degrees due to aging, commonly rotator cuff injuries, and repair is not as good as it used to be. There are four main sources of blood flow in tendons, namely, the tendon-muscle belly migration, tendon attachment adjacent to bone tissue or periosteal blood vessels, peritendinous tissue and synovial sheaths wrapped around the site of the tendon ligament, and so on.