the mass of specialized cardiac muscle fibers that normally acts as the "pacemaker" of the cardiac conduction system; it lies under the epicardium at the upper end of the sulcus terminalis.
Synonym(s): nodus sinuatrialis [TA], atrionector, Flack node, Keith and Flack node, Keith node, Koch node, sinoatrial node, sinus node
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atrionector(ā″trē-ō-nek′tŏr, tor″) [ atrium + nectere, to connect]
An obsolete term for sinoatrial node.
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