Heart is established by the sinoatrial node, the heart's pacemaker. Here an electrical signal is created that travels through the heart, causing the heart muscle to contract. The sinoatrial node is found in the upper part of the right atrium near to the junction with the superior vena cava. The electrical signal generated by the sinoatrial node travels through the right atrium in a radial way that is not completely understood. It travels to the left atrium via Bachmann's bundle, such that the muscles of the left and right atria contract together. The signal then travels to the atrioventricular node. This
Heart development before the fusion of the endocardial tubes. The heartbeat begins in the region of the pacemaker which has a spontaneous depolarization time faster than the rest of myocardium. The primitive ventricle acts as initial pacemaker. But this pacemaker activity is actually made by a group of cells that derive from the sinoatrial right venous sinus. These cells form an ovoid sinoatrial node (SAN), on the left venous valve. After the development of the SAN, the superior endocardial cushions begin to form a pacemaker as known as the atrioventricular node. With the development of the SAN, a band of specialized conducting