sinus node

sinoatrial node   n.  A small mass of specialized cardiac muscle fibers located in the posterior wall of the right atrium of the heart that acts as a pacemaker by generating at regular intervals the electric impulses of the heartbeat. Also called sinoauricular node, sinus node.

Main Entry: sinoatrial node
Function: noun
: a small mass of tissue that is made up of Purkinje fibers, ganglion cells, and nerve fibers, that is embedded in themusculature of the right atrium of higher vertebrates, and that originates the impulses stimulating the heartbeat called also S-A node, sinus node

sinoatrial node n.
Abbr. SAN
A small mass of specialized cardiac muscle fibers located in the posterior wall of the right atrium of the heart that acts as a pacemaker of the cardiac conduction system by generating at regular intervals the electric impulses of the heartbeat. Also called sinoauricular node, sinus node.

sinoatrial node   (sī'nō-ā'trē-əl)  Pronunciation Key  A small mass of specialized cardiac muscle fibers that acts as a pacemaker by initiating and maintaining normal heartbeat and cardiac rhythm. It is located in the right atrium.