The left ventricle is slightly smaller and covered with thick walls. Its wall is three times as thick as the wall of the right ventricle. Fleshy columnar corni arise from the walls of the ventricles. It has a bicuspid lens on one side and a semilunar lens on the other. It carries O2-rich blood through the semilunar capillaries into the aorta or aorta. Between the two ventricles is the interventricular septum.