Superior-inferior classification

The mediastinum can be divided up arbitrarily into a number of compartments for the purposes of description of structures therein. One traditional way of doing this is to designate compartments according to a plane between the lower border of the fourth thoracic vertebra and the manubrium of the sternum. Within the mediastinum, the region above this plane and below the superior thoracic aperture is the superior mediastinum; the region below this plane is the inferior mediastinum.

The inferior mediastinum can be further divided up according to the position of the heart:

• anterior mediastinum: anterior to the fibrous pericardium within the mediastinal cavity
• middle mediastinum: the pericardial sac, its contents and lateral projections
• posterior mediastinum: posterior to the fibrous pericardium within the mediastinal cavity