<prompt> Depolarization of the ventricular muscles starts atLeft side of the inventricular septumRight side of the septumApex of the heartAV groove  <response>: A. i.e. Left side of the interventricular septum 549- Ganong 22nd 492- Ganong 23rd In humans - depolarization of the ventricular muscle starts at the left side of the interventricular septum and moves first to the right across the midportion of the septum. The wave of depolarization then spreads down the septum to the apex of the heart Depolarization initiated in the SA node spreads radially through the atria then converges on the AV node. 