The atria are electrically isolated from the ventricles by the fibrous rings which form the aortic, mitral, and tricuspid valves, and by the central fibrous body. These structures together form the fibrous skeleton of the heart. 1.4.1 1.4.2 1.4.3 1.4.4 1.4.5 1.4.6 1.4.7 1.4.8 1.4.9 1.4.10 1.4.11 1.4.12 Book traversal links for 1.4.0 Atrio Ventricular Conduction 1.3.1 Up 1.4.1