Depolarization of the ventricular muscles starts at

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.