The causes of pain inside the left rib cage: 1, consider the pain caused by rib problems, such as soft tissue injuries, trauma, fractures of the rib cage, and intercostal neuralgia leading to pain. 2, the left rib cage belongs to the lung disease, consider the inflammation of the lung, tumors, abscesses, pleural effusion, etc., leading to pain in the left rib cage. 3, the left rib cage is the heart part, consider the emergence of coronary heart disease, angina pectoris The pain occurs due to coronary heart disease, angina pectoris, myocardial infarction, etc. Be sure to identify the cause and make a specific diagnosis.