mediastinum

The region in mammals between the pleural sacs, containing the heart and all of the thoracic viscera except the lungs.

In anatomy, a median septum or partition between two parts of an organ, or between two paired cavities of the body; especially, the membranous partition separating the right and left thoracic cavities, formed of the two inner pleural walls.

The region in mammals between the pleural sacs, containing the heart and all of the thoracic viscera except the lungs.

the part of the thoracic cavity between the lungs that contains the heart and aorta and esophagus and trachea and thymus