Why are the internal walls of the ventricles not smooth?

The internal walls of the ventricles are not smooth due to the presence of structures called trabeculae carneae, which are irregular muscular ridges. These projections increase the surface area of the ventricular walls and contribute to the efficiency of heart contractions. Additionally, the rough texture helps prevent the adhesion of the heart valves to the ventricular walls during systole, ensuring proper function during the cardiac cycle.