The anterior mediastinum is a part of the inferior mediastinum that is located between the body of the sternum and the pericardial sac.

Its superior boundary is the transverse thoracic plane separating it from the superior mediastinum, while its inferior boundary is the diaphragm. Laterally, it is bounded by the mediastinal part of the parietal pleura on each side.

A major structure found in the anterior mediastinum is the inferior extension of the thymus. 

There are also other tissue and organs, such as fat, connective tissue, lymph nodes, mediastinal branches of the internal thoracic vessels, and sternopericardial ligaments.