<prompt> True about SA node is all exceptSupplied by nodal aeryPrimary pacemakerSupplied by left vagus nerveMade up of nodal cells and connective tissue  <response>: Sinoatrial Node SA node It is known as the pacemaker of the hea.It generates an impulse at the rate of about 70min and initiates the heabeat.It is horseshoe-shaped and is situated at the atriocaval junction in the upper pa of the sulcus terminalis.The impulse travels through the atrialwall to reach the AV node. Except for a pa of the left branch of the AV bundle supplied by the left coronary aery the whole of the conducting system is usually supplied by the right coronary aery. 