What are between the heart and the spine?
Answer:
Vagus nerves as they pass posterior to the roots of the lungs
Esophagus throughout its length inside the chest.
Branches of the descending thoracic aorta.
Azygos system of veins.
Thoracic duct, Sympathetic trunks and their branches.
Are the contents of postrior mediastinum lying posterior to heart and anterior to spine .
Hi. Lungs mostly.
lungs
If you denote anatomically, there is abundantly there. First of adjectives, there are the lungs, which are surrounded by pleural membranes, next there are the pulmonary arteries and vein, and the mediastinal lymphatic nodes, which are scattered throughout the thoracic cavity. Also the trachea and the esophagus. The vena cava, and the descending aorta are also posterior to the heart.
lungs and i reason the back of the ribs
Look up "posterior mediastinum" surrounded by Wiki or better. It'll keep you busy a while.
Lungs and muscle