1) Heart.

2) Pericardium.

3) Arteries:

4) Veins:

5) Nerves:

  • Phrenic nerves.
  • Deep cardiac plexus.

6) Lymph nodes: Tracheobronchial lymph nodes.

7) Tubes:

  • Bifurcation of trachea.
  • Left and right principal bronchi.

The main contents of middle mediastinum are pericardium and its contents (example, the heart and roots of its great vessels).