7.1. Introducing the Mediastinum

Defining the Mediastinum

The mediastinum is the central region, or space, of the thoracic cavity. Essentially, the thoracic cavity can be divided into the two lungs (+ pleurae) and the mediastinum. So, the lungs lie lateral to the mediastinum. The mediastinum contains lots of important structures including the HEART, trachea and great vessels leaving/entering the heart. The location of the mediastinum is shown within the thoracic cavity in the accompanying image. Note that the diagram has been sketched in the transverse plane while being viewed from below. The contents of the subdivisions of the mediastinum are shown too - the lists look intimidating, but just remember that the heart and pericardium lie in the inferior middle mediastinum - if you know this, you can easily place the other thoracic structures in front, behind or above the heart!