Hello, l am Bettina Heidecker. I'm a cardiologist at the University Hospital of Zurich. Thank you for joining this course about the anatomy of the heart. First, l would like to start with our learning objective. We will describe the location of the heart, the sternocostal relationships. Then we will talk about the double layer of the pericardial sac. And we would like you to understand the features, the main features of the right and left ventricle. First, I would like to start by locating the heart in the chest. The position of the heart is in the middle medial sternum within the pericardium. The heart is located behind the sternum and the second to sixth costal space, in front of the fifth to eighth thoracic vertebrae. The basic anatomy is best explained by describing the course of the blood flow through the heart. The deoxygenated blood returns through the superior vena cava into the inferior vena cava and into the right atrium where it then passes through the tricuspid valve into the right ventricle. From there, it gets ejected through the pulmonic valve into the pulmonary artery and into the pulmonary circulation. Then it returns oxygenated blood into the left atrium, through the mitral valve into the left ventricle, from where it gets ejected into the aorta and into the systemic circulation. The aorta contains the aortic valve. The outer structures of the heart are divided into the sternocostal surface and the diaphragmatic surface. The sternocostal surface consists of the right atrium and the right ventricle and to a small part it is constituted of the left atrium and the left ventricle. It is directed anteriorly and upwards. The diaphragmatic surface mostly consists of the left ventricles. It points downwards towards the diaphragm and posteriorly. The left ventricle forms the left ventricular apex which is an important mark, an atomic mark. For the physical exam, it's also called the point of maximum intensity. It's located in the midclavicular line and the fifth intercostal space. It's important for us to estimate the heart size by palpitating it. If it's laterally displaced, it's a sign for enlargement of the heart. If it's hyperdynamic, it points more towards a hypertrophy of the heart. The three borders of the heart are the right border created by the right atrium, the left border with the left ventricle and the inferior border with the right ventricle. The pericardium is a multilinear membrane that covers the heart. It consists of two main walls: the superficial fibrous pericardium and the deep serous pericardium. The serous pericardium is divided into two more layers: the parietal layer, lining the internal surface of the fibrous pericardium and the visceral layer of the epicardium, lining the surface of the heart. The two layers of the serous pericardium are separated by the fluid filled pericardial cavity. The functions of the pericardium are to anchor the heart, protect it in a friction free environment and prevent over filling of the heart with blood. The inner structures of the heart consist of the chambers separated by the valves and septal structures. The interatrial septum separates the right atrium from the left atrium. It contains the fosso valus, which allows blood flow during fetal life from the right atrium into the left atrium and then into the systemic circulation, because the blood in fetal life is already oxygenated by the placenta. After birth, this hole closes and what remains is the fossa ovalis, which is closed in the majority of the population, but in 25% approximately, it remains open. The interventricular septum is located between the right ventricle and the left ventricle. It has an upper membranous part and a lower muscular part. Moving on to the chambers of the heart, we will start with the right atrium. The right atrium collects, as mentioned, the venous blood through the vena cava superior and inferior. Here's a view from the right heart border, in the right atrium you can see the fossa ovalis. Right below the fossa ovalis, is the orifice of the coronary sinus. The coronary sinus collects the venous blood from the heart, so it's deoxygenated. It's basically the blood that the heart used for its own consumption. The pectonate muscles covered in the wall of the right atrium. The right ventricle receives blood through the right atrium and the tricuspid valve, and ejects it through the pulmonary artery with its pulmonic valve into the pulmonary circulation. The walls of the right ventricle contain elevated ridges and bridges of muscle called tribiculic carnea. Then we also have the papillary muscles which are joined to the leaflets of the tricuspid valve through thin tendonous threads which are called chordae tindineae. The left atrium collects the oxygenated blood returning from the pulmonary circulation via the pulmonary veins which also create most of the wall of the left atrium. Illustrated on this graph are the pulmonary veins on the right as well as on the left side. Also visualized is again the course of the coronary sinus between the left atrium and between the atrium and the ventricle. Both atrial have protruding auricles or atrial appendage. The left ventricle receives the oxygenated blood from the left atrium via the mitral valve and pumps it into the systemic circulation through the aorta and the aortic valve. Similar to the right ventricular walls, the walls of the left ventricle are lined with elevated regions and bridges of muscle called trabeculae carneae. The papillary muscles keep the mitral valve in place. Given that the left ventricle has to pump blood into the systemic circulation, which has much greater pressure than the pulmonary circulation, the walls of the left ventricle are about as three times as thick. The heart valves separate the atria from the ventricles or the ventricles from the great blood vessels, which would be the pulmonary artery or the aorta. The valves are pushed open by increasing blood pressure differences on both sides of the valves, steering the cardiac psyche. For the pulmonic and aortic valve, this pressure difference occurs during systole for the tricuspid and mitral valve during diastole. The heart valves ensure that the blood flow is guided in only one direction. We distinguish valves with leaflets, also called atrial ventricular valves, and valves with cusps, also called semiluna valves. Listed are the four main valves: the tricuspid, mitral valve, aortic and pulmonary valve. The semilunar valves, the pulmonic valve, and the aortic valve prevent backflow of the blood into the ventricles. The pulmonic valve is located between the right ventricle and the pulmonary trunk, and the aortic valve between the left ventricle and the aorta. The four main valves are situated within fibrous rings of the cardiac skeleton. They are covered by endocardium with a core of connective tissue. Also the coronary sinus and the inferior vena cava have small valves. So here again, a summary of what we just learned: We mentioned that the systemic blood, the deoxygenated blood, comes back through the superior and inferior vena cava into the right atrium, where it passes through the tricuspid valve into the right ventricle. From there, it gets ejected into the pulmonic artery with the pulmonic valve, where it gets oxygenated in the pulmonary circulation. And then it returns into the left atrium through the mitral valve into the left ventricle. And from there, it gets ejected through the aorta with its aortic valve into the systemic circulation. Thank you for your attention.
