The sino atrial or sinus node is a spindle-shaped structure located in the posterior wall of the right atrium at its junction with the superior vena cava. It is often referred to as the SA node. 1.2.1 1.2.2 1.2.3 1.2.4 1.2.5 1.2.6 1.2.7 Book traversal links for 1.2.0 SA Node & Pacemakers 1.1.3 Up 1.2.1