atrioventricular (AV) node

a·tri·o·ven·tric·u·lar (AV) node

(ā'trē-ō-ven-trik'yū-lăr nōd) [TA] A small node of modified cardiac muscle fibers located near the ostium of the coronary sinus; it gives rise to the AV bundle of the conduction system of the heart.