Expansion
Trachea and heart in front, vertebral column and aorta behind, arch and azygos to the sides
Expansion
Anteriorly, from above down:
- Trachea, then the left main bronchus
- Right pulmonary artery
- Pericardium and the left atrium
- Diaphragm
Posteriorly
- Vertebral column, then the thoracic duct and azygos vein
- Descending thoracic aorta in the lower part, as the oesophagus crosses in front of it
To the left - aortic arch, left subclavian artery, thoracic duct, left pleura
To the right - azygos vein arching forwards, right pleura
Two consequences follow. A grossly enlarged left atrium displaces the oesophagus posteriorly, visible on a barium swallow. And because only pleura separates the oesophagus from the lung, perforation rapidly produces mediastinitis and a pleural effusion.