• cavity
  • The mediastinum is the cavity that separates the lungs from the rest of the chest. (humpath.com)
  • The mediastinum (from Medieval Latin mediastinus, "midway") is the central compartment of the thoracic cavity surrounded by loose connective tissue, as an undelineated region that contains a group of structures within the thorax. (wikipedia.org)
  • fibrous
  • superior and inferior sternopericardial ligaments Middle mediastinum Bounded: pericardial sac - It contains the vital organs and is classified into the serous and fibrous pericardium. (wikipedia.org)