The second and third ribs are located in the thorax, the anterior end of the rib is connected to the corresponding rib notch of the sternum, and the posterior end of the rib head is connected to the transverse process of the second and third thoracic vertebrae, so that the second rib can be localized by the position of the sternal angle on the surface of the body, and the third rib is the third rib counting downward from the second rib in sequence. The second rib is counted downward from the second rib to the third rib. The sternal angle is flat on both sides of the second rib, so the second rib can be localized on the surface of the body by the sternal angle. The rectangular flat bone in the center of the anterior chest wall is the sternum, which can be divided into stalk, body and raphe from top to bottom, and the joint between the stalk and the body is the sternal angle, which is slightly protruding forward and can be touched on the surface of the body, and the ribs connected on both sides of the sternal angle are the second ribs. The third rib is located below the second rib. After locating the second rib through the sternal angle, the third rib is located downwards. If it is difficult to locate the third rib on the surface due to obesity, X-rays and other imaging tests can be used to assist in localization.