The mediastinum is a non-delineated group of structures in the thorax (chest), surrounded by loose connective tissue.

Anatomy

It is surrounded by the chest wall anteriorly, the lungs laterally and the spine posteriorly. It is continuous with the loose connective tissue of the neck, and extends inferiorly onto the diaphragm.

Structures inside the mediastinum include the heart, aorta, vena cava, pulmonary artery, pulmonary vein, oesophagus, thymus, thoracic duct, the phrenic nerve and many smaller structures. Occasionally, the thyroid and parathyroids may extend into the mediastinum.

Role in disease

Mediastinitis is inflammation of the tissues in the mediastinum, usually bacterial and due to rupture of organs in the mediastinum. As the infection can progress very quickly, this is a serious condition.

Pneumomediastinum is the presence of air in the mediastinum, which can lead to pneumothorax, pneumoperitoneum , and pneumopericardium if left untreated in some cases, though that does not always happen and sometimes those conditions actually are the cause, not the result, of pneumomediastinum.

These two conditions frequently accompany Boerhaave's Syndrome, or spontaneous esophageal rupture.