Is there any difference between the wall of atria and the wall of ventricles?
Atrial walls are thinner compared to the thickness of ventricular walls.
Moreover, embedded in the atrial wall is pace maker of heart.
Atria of heart are receiving chambers while ventricles pump the blood forcefully to all organs of body. Hence muscle mass around ventricles is thickened compared to that around atria.
Moreover, myocardium of both atria together form a functional syncytium and it remains completely separated from ventricular myocardial syncytium.