This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Heart: Rhythmical Excitation of the Heart, Subject name: Physiology
Which of the following is the order of activation after stimulation of Purkinji fibrs is : 
Select and explain. 
A. Septum -> Endocardium -> Epicardium, B. Endocrdium -> Septum -> Epicardium, C. Epicardium -> Septum -> Endocardium, D. Septum -> Epicardium -> Endocardium
A: Septum -> Endocardium -> Epicardium
Answer: A: Septum -> Endocardium -> Epicardium 
Explanation: Ans. is 'a' is Septum - Endocardium - Epicardium Order of spread of cardiac excitationSA node - AV node - Bundle of HIS* - Purkinje system* - Ventricular muscle.SA node - AV node - Bundle of HIS* - Purkinje system* - Ventricular muscle.Order of activation of ventricular muscle.Depolarization starts of the left side of the interventricular septum* - Moves first to the right across the mid portion of the septum* - Activation of anteroseptal region of the ventricular myocardium (Apex).- Activation of the major portion of ventricular myocardium from the endocardium to the epicardium.Last parts of the heart to be depolarized ar? the postero basal portion of the left ventricle *The pulmonary conus *Upper most portion of the septum*