Last revised by Raymond Chieng on 10 Oct 2023

The pericardium is a conical, flask-like, fibroserous sac which contains the heart and the roots of the great vessels and defines the middle mediastinum

The pericardium is made of two sacs in one. The outer sac is the fibrous pericardium and the inner sac is the double-layered serous pericardium. Layers of serous pericardium are divided by the pericardial space, which only contains 15-50 mL of serous fluid 10. Each layer has quite different structure and functions (from external to internal):

  • fibrous pericardium: tough connective tissue continuous with and bound to the central tendon of the diaphragm (pericardiophrenic ligament), the roots of the great vessels, the pretracheal layer of the deep cervical fascia and the sternum via the superior (to manubrium) and inferior sternopericardial ligaments (to xiphoid process)

  • serous pericardium: composed of a single layer of flattened mesothelial cells reflected on itself at the root of the great vessels to form a closed sac. The two layers are:

    • parietal serous pericardium: lines the deep surface of the fibrous pericardium and is inseparable from it

    • visceral serous pericardium: covers heart and great vessels forming the epicardium. Some fat exists between the epicardium and myocardium and it increases with age. The amount of fat may become more extensive at the anterior and lateral cardiophrenic angles, where it is known as pericardial fat pad 10.

The serous pericardium is invaginated by the heart and great vessels forming two sinuses:

Adjacent to these sinuses, there may be one or several pericardial recesses:

  • aortic recesses - arise from the transverse sinus 

    • superior aortic recess: from its mouth located inferiorly, it ascends posterior to and then to the right of the ascending aorta and ends at the level of the sternal angle 

    • inferior aortic recess: diverticulum descending from the superiorly located mouth to run between the lower ascending part of the aorta and the right atrium 

  • pulmonic recesses - arise from transverse sinus 

  • postcaval recess: posterior to the superior vena cava, superior to the right superior pulmonary vein and inferior to the right pulmonary artery, with a mouth that opens superolaterally to the right

  • posterior pericardial recess: arises superiorly from oblique sinus, posterior to the right pulmonary artery and medial to the bronchus intermedius

  • pulmonary venous recesses - arise from the pericardial cavity proper

  • tracheobronchial nodes

  • prepericardial nodes 9

  • pericardium appears as a thin high-density line between the lower-density mediastinal and epicardial fat 10

  • low density pericardial recesses and sinuses between the great vessels should not be mistakened as lymph nodes 10

  • fibrous and serous pericardium cannot be delineated and the upper limits of normal for pericardial thickness is 2 mm 2

  • often not imaged over the left ventricle 3

  • T1 and T2: appears as a low signal rim between the higher-signal mediastinal and epicardial fat 2,3

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