The phenomenon of pain with tendons under the breast includes the following: 1. It may be a disease of the breast itself, common mastopexy, ductal dilatation of the breast will appear painful, and sometimes you can feel the rope-like structure, tenderness is very obvious, more obvious in the course of the menstrual cycle, with the end of the period may gradually reduce the pain. 2. It may be due to inflammation of the breast, including lactation. The actual pain is usually a result of the fact that the pain is not only in the breast, but also in the organs other than the breast, including the rib neuritis and the rib chondritis.