The pain in the back under the lumbar bone may be caused by several reasons: first, it may be caused by soft tissue lesions, such as muscle spasm or aseptic inflammation of the deep fascia, which are more common in this area. These diseases are often caused by excessive use of the shoulder joint or cold conditions, which leads to muscle spasm and inflammation of the deep fascia, resulting in pain in this area. Second, due to injury to the scapula, such as direct violence to the scapula, or excessive movement of the shoulder joint, resulting in contusion or even fracture of the scapula, pain may occur. In addition, if the muscles and tendons here are strained, it may also cause pain here. Third, due to frozen shoulder, patients suffering from frozen shoulder will not only have pain inside the shoulder joint, but also in the upper and lower parts of the shoulder joint. Fourth, it is caused by the internal organ lesions in the chest cavity, for example, if there is a lesion in the heart, it may cause pain in the left scapula, and if there is pneumonia or pleural adhesions in the chest cavity, it may also cause pain here.