part of part of contributes to morphology of conducting system of heart sinoatrial node BTO:0004358 EHDAA2:0004184 EMAPA:35772 FMA:9477 GAID:561 Koch's node MA:0000097 MESH:D012849 OpenCyc:Mx4rOhejDGMcEd2AAABQjYGu0g SA nodal muscle tissue SA node TAO:0005069 The part of the cardiac conduction system that controls the timing of heart muscle contraction. It relays electrical signals to the AV node[GO]. Subdivision of conducting system of heart at the junction of the right atrium and the superior vena cava, around the sinoatrial nodal branch of right coronary artery and is continuous with the internodal tract[FMA]. UBERON:0002351 UMLS:C0037189 WP:Heart states: "The SA node is found in all amniotes but not in more primitive vertebrates. In these animals, the muscles of the heart are relatively continuous and the sinus venosus coordinates the beat which passes in a wave through the remaining chambers. Indeed, since the sinus venosus is incorporated into the right atrium in amniotes, it is likely homologous with the SA node. In teleosts, with their vestigial sinus venosus, the main centre of coordination is, instead, in the atrium.". Note however that ZFA has SA node. ZFA:0005069 cardiac pacemaker node of Keith-Flack nodus sinuatrialis nodus sinuatrialis sinoatrial node sinu-atrial node sinuatrial nodal muscle tissue sinuatrial node sinus node sinus node of Keith and Flack uberon cardiac muscle tissue of myocardium conducting tissue of heart