part_of part of part of has part has part has_part surrounded by pericardial cavity serous pericardium fibrous pericardium pericardial sac RETIRED_EHDAA2:0001443 FMA:9868 pericardium SCTID:361326002 UBERON:0002406 A double-walled sac containing the heart and the roots of the great vessels. pericardium thoracic segment organ serous sac