Wall between the lower chambers of the heart is called the interventricularBetween the two ventricles (lower chambers of the heart) septumWall separating two chambers of the heart, which separates the right ventricleThe lower thick walled chambers of the heart (left and right) which receive blood from the atriumUpper thin walled chambers of the heart (left and right). They receive the blood returning to the heart and pump out into the body from the left ventricleThe lower thick walled chambers of the heart (left and right) which receive blood from the atriumUpper thin walled chambers of the heart (left and right). They receive the blood returning to the heart and pump out into the body.