part_of part of part of has part has part has_part develops_from develops from develops from heart chambered heart vertebrate heart cardium branchial heart A myogenic muscular circulatory organ found in the vertebrate cardiovascular system composed of chambers of cardiac muscle. It is the primary circulatory organ. mesoderm-derived structure heart tube cardiac chamber thoracic segment organ primary circulatory organ structure with developmental contribution from neural crest heart plus pericardium