The fibrous skeleton of the heart functions in all of these ways except in the fibrous skeleton of the heart functions in all of these ways except in acting as the point of insertion for bundles of cardiac muscle in the atria and ventricles anchoring the valve cusps causing direct spread of electrical impulses from the atria to the ventricles lining the heart chambers, covering the heart valves, and forming the ridge of the crista terminalis preventing overdilation of the valve openings