The mediastinum is the area in the chest that lies between the lungs and extends from the sternum to the vertebral column. It acts as a conduit for structures crossing the thorax on their way into the abdomen. It is an important region which includes the heart, the esophagus, the trachea, and large blood vessels as well as the lymph nodes.
The mediastinum is divided into two parts anatomically, superior and inferior, and into three areas for radiology: the Anterior; the Middle and the Posterior. For once, the correct names, medically, are easy to understand! Other good news is that mediastinal tumors are rare.