Anatomy, Thorax, Mediastinum

The thoracic mediastinum is the compartment that runs the length of the thoracic cavity between the pleural sacs of the lungs. This compartment extends longitudinally from the thoracic inlet to the superior surface of the diaphragm. Although there are no physical barriers between compartments other than the pericardium, the mediastinum is typically discussed based on subdivisions. The four-compartment model divides the mediastinum into the superior, anterior, middle, and posterior portions. The mediastinum houses many vital structures including the heart, great vessels, trachea, and essential nerves. It also functions as a protected pathway for structures traversing from the neck, superiorly, and into the abdomen, inferiorly. The mediastinum is also clinically significant due to the variety of physical anomalies and pathologies that can occur in this region.