Pericardial SinusPronunciation/per-i-kar-dee-al SIN-us/CategoryAnatomySingularPericardial SinusPluralPericardial SinusesDefinitionA space around the heart, bordered below by the dorsal diaphragm.EtymologyFrom Latin 'peri-', meaning 'around', and 'cardi-' meaning 'heart'.ExampleThe pericardial sinus in insects is filled with hemolymph.Related TermsHeartDiaphragmHemolymph