sinoatrial node: Meaning and Definition of

si'no•a'tri•al node'

Pronunciation: (sī'nō-ā'trē-ul, sī"-), [key]
— Anat. Anat.
  1. a small mass of tissue in the right atrium functioning as pacemaker of the heart by giving rise to the electric impulses that initiate heart contractions. Also called
Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease.