1. AR Figure 78 – Myocardium: Conducting system of heart,
   1. Myocardium
      1. Myocardium: It is the heart's main component and serves as the contractile component. It is thinner in the atria and thicker in the ventricles. The left ventricle's myocardium is thicker than the right ventricle's. (2)
   2. Vortex of heart
      1. Vortex of the heart: The vortex of the heart is situated at the apex, where the two ventricles meet, the muscle fibers create a swirl. This intricate arrangement resembles a vortex, suggesting a dynamic and spiraling pattern within the heart. (1)
   3. Conducting system of heart
      1. Conducting system of the heart: It is specialized tissue on the inner aspect of the myocardium that conducts the heart's electrical impulses. (3)
2. Conducting system of heart
   1. AR Figure 79 – Myocardium: Conducting system of atria,
      1. Sinuatrial node
         1. Sinu-atrial node: The SA node is shaped like a tadpole and is situated in the right atrium near the superior vena cava, in the terminal groove. Multiple interdigitations arise from the SA node, serving for a better connection between the node and the myocardium. (1,3)
      2. Atrioventricular node
         1. Atrioventricular node: The AV node is a particular structure of cells located in the right atrium, somewhere near the center of the heart, in a landmark known as the Triangle of Koch. (1,3)
      3. Atrioventricular bundle
   2. Atrioventricular bundle
      1. Atrioventricular bundle is a bundle of fibres that penetrate the fibrous body, to conduct the electrical impulses from the AV node to the ventricles. (1,3)
      2. AR Figure 81 – Myocardium: Left bundle branch,
         1. Left bundle branch
            1. Left bundle branch: - located beneath the endocardium, is a segment of the bundle of His that extends toward the middle of the left ventricle. It divides into smaller bundles and spreads throughout the left ventricle. (6)
            2. Left anterior branch of atrioventricular bundle
            3. Left anterior branch of atrioventricular bundle: It courses in the subendocardium along the superior aspect of the left ventricle towards the anterolateral papillary muscle. It spreads over the anterolateral papillary muscle in every direction. (3,4,5)
            4. Left intermediate branch of atrioventricular bundle
            5. Left intermediate branch of atrioventricular bundle: It courses superficialy through the subendocardium along the septum of the left ventricle towards the the apex. (3,4)
            6. Left posterior branch of atrioventricular bundle
            7. Left posterior branch of atrioventricular bundle: It courses superficialy through the subendocardium along the inferior aspect of the left ventricle towards the posteromedial papillary muscle. It spreads over the posteromedial papillary muscle in every direction. (3,4,5)
      3. AR Figure 80 – Myocardium: Right bundle branch,
         1. Right bundle branch
            1. Right bundle branch: The RBB advances trough the subendocardial along the septal wall of the right ventricle. (1) As it runs down the right ventricle, it reaches a point where it crosses the ventricular cavity through the moderator band and branches out to reach the apex and the base of the right ventricle. (3)
   3. Subendocardial branches
      1. Subendocardial branches: The Purkinje fibers continue the bundle branches like a mesh that lines the subendocardium (inner part of the myocardium). The Purkinje fibers interface with the working cardiac muscle cells. (1,2,3,4)
         1. AR Figure 78 – Myocardium: Conducting system of heart,