The Middle Mediastinum

The pericardium:

Double walled fibroserous sac

Encloses:

• Heart
• Roots of pulmonary trunk and aorta
• Termination of pulmonary veins and vena cavae.
  
  Location:
  
  
• Middle mediastinum
• Posterior to the body of the sternum and th 2 nd to 6 th costal cartilages
• Anterior to T5-8 vertebrae.

Relations

Superior:Pierced by the

• Aorta,
• pulmonary trunk
• Superior vena cavae.
• In children it is related to the thymus

Inferiorly:

• Separated from the liver and fundus of the stomach by the central tendon of the diaphragm with which it fuses.

Anteriorly:

• Seperated from the body of sternum and 2 nd to 6 th costal cartilages by pleura with the lungs except at the cardiac notch.
  
  
• The internal thoracic vessels and parasternal nodes run along the lateral borders of the sternum.
  
  
• In the midline it is attached to the sternum by sternopericardial ligaments

Posteriorly:

• The contents of the posterior mediastinum

Laterally:

• The phrenic nerve
  
  
• Periocardiophrenic vessels
  
  
• Mediastinal surface of the lungs and their covering visceral pleura( what structures are found at the hilum of the lungs?)

Organization of the pericardium

Consists of two layers:

• The fibrous - tough aponeurosis-like outer indistensible jacket
• The serous - moist inner lining with two layers
  
  (+) Parietal layer lining the inside of the fibrous pericardium
  (+) Visceral pericardium intimately lining the heart surface.