Definition of sinoatrial node in US English:

sinoatrial node


  • A small body of specialized muscle tissue in the wall of the right atrium of the heart that acts as a pacemaker by producing a contractile signal at regular intervals.

    • ‘This activity arises not from excitatory nerve fibres, but spontaneously within the heart itself from a small clump of pacemaker cells near the point where the vena cava joins the right atrium: the sino-atrial node.’
    • ‘The classical concept of the source of cardiac rhythm is that it originates from the sino-atrial node.’
    • ‘Procoralan exclusively reduces heart rate by a specific action on the sino-atrial node.’


Early 20th century: from sinus + atrial (see atrium).


sinoatrial node

/ˌsīnōˌātrēəl ˈnōd/