epimyocardium
noun
epi·myo·car·di·um
| \ ˌep-ə-ˌmī-ə-ˈkärd-ē-əm
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plural epimyocardia\ -ē-ə
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Medical Definition of epimyocardium
: the undifferentiated splanchnic mesodermal layer of the embryonic heart that subsequently differentiates into myocardium and epicardium