Local palpable muscle belly and tendon junction slightly missing and subsidence is mostly seen in muscle strain, tendon by collagen fibers, does not have the ability to contract, its role is to transfer the muscle contraction force to the bone tissue. Tendon fibers are corrugated at rest, and when stretched, the corrugation disappears. When overstretched, collagen fibers can show micro-injury, and even tendon rupture occurs. What are the causes of muscle strain? Muscle strain is an injury caused by sharp contraction or excessive pulling of the muscle during exercise. This tends to happen during long jumps, pull-ups and sit-up exercises. After a muscle strain, the strained area is in severe pain, the hand can feel the muscle tension forming a cord-like hard lump, tenderness is obvious, localized swelling or subcutaneous bleeding, and the activity is obviously limited. Muscle strains, to immediately carry out cold treatment – with cold water local or with a towel wrapped in ice decision cold compresses, and then use a bandage appropriate force wrapped around the injury site, to prevent swelling. In the relaxation of the injured part of the muscle and elevate the injured limb at the same time, can take some pain, stop bleeding drugs. 24 hours to 48 hours after the removal of bandages. According to the condition of the injury, you can apply the paste to activate blood circulation and reduce swelling, and you can apply hot compresses or massage the injured part with light techniques. For serious muscle strains, such as pulling the muscle belly or tendon off, you should go to the hospital for surgical suture as soon as possible. The body’s response to a muscle strain is immediately inflammatory, with more edema than bleeding. Severe muscle tears produce hemorrhage and sometimes subcutaneous hemorrhage and bleeding, and CT examination shows that the main response is edema and inflammation. The main reaction is edema and inflammation on CT scan. Bleeding often occurs from the muscle into the fascial space or into the subcutis. Clinical examination reveals that muscle strains often occur in the distal part of the muscle (except for the Tsukiguni rope muscle, which is strained proximally and laterally, mainly in the biceps femoris muscle group). Surgical exploration confirms that most of the ruptures of the muscle fibers are close to the muscle-tendon junction.