The middle mediastinum is located centrally in the thoracic cavity and its borders are as follows:

• Anteriorly - anterior part of the perciardium;
• Posteriorly - posterior part of the pericardium;
• Laterally on each side - mediastinal part of the parietal pleura;
• Superiorly - transverse thoracic plane;
• Inferiorly - superior surface of the diaphragm.

Content

The middle mediastinum contains the following structures:

• Heart and pericardium
• Bifurcation of trachea (read more!), right and left main bronchi (read more!)
• Origins of the great vessels:
  • Ascending aorta
  • Pulmonary trunk
  • Superior vena cava (read more!) 
• Various nerves:
  • Right and left phrenic nerves
  • Cardiac plexus
• Lymphatics, including tracheobronchial lymph nodes