Lecture 1a, CVS Anatomy and Coronary Circulation.md

CVS Anatomy and Coronary Circulation ==================================== **Date:** 05 Jun, 2023 ------------------------------------------------------------------------ Introduction ------------ This covers the core content of cardiovascular (CVS) anatomy, with a focus on the structure and func...

CVS Anatomy and Coronary Circulation ==================================== **Date:** 05 Jun, 2023 ------------------------------------------------------------------------ Introduction ------------ This covers the core content of cardiovascular (CVS) anatomy, with a focus on the structure and function of the heart, major blood vessels, pericardium, and coronary circulation. We will discuss the anatomy of the heart, its position, external features, and the course of blood flow into and out of the heart. This will also explore the pericardium, its relationship to the phrenic nerves, and problems associated with fluid accumulation in the pericardial sac. Finally, we will delve into the main vessels comprising the coronary circulation and the venous drainage of the heart. ------------------------------------------------------------------------ Main Points ----------- ### Structure and Relations of the Heart and Major Blood Vessels: - Anatomy of the heart and its position in situ: - The heart is a muscular organ located in the mediastinum, slightly left of the midline. - It is surrounded by the pericardium, a protective sac that anchors the heart and limits its motion. - External features of the heart: - The heart has four chambers: two atria (right and left) and two ventricles (right and left). - The coronary sulcus separates the atria from the ventricles. - The anterior interventricular sulcus and the posterior interventricular sulcus divide the right and left ventricles. - Course of blood flow into and out of the heart through major vessels: - Deoxygenated blood returns to the right atrium through the superior and inferior vena cava. - Blood passes from the right atrium to the right ventricle through the tricuspid valve. - The right ventricle pumps blood to the lungs via the pulmonary artery for oxygenation. - Oxygenated blood returns to the left atrium through the pulmonary veins. - Blood passes from the left atrium to the left ventricle through the bicuspid (mitral) valve. - The left ventricle pumps oxygenated blood to the rest of the body through the aorta. ### Structure and Function of the Pericardium: - Fixation and limitation of heart motion: - The pericardium holds the heart in place within the thoracic cavity. - It prevents excessive movement and displacement of the heart during physical activity. - Prevention of heart overfilling: - The pericardium acts as a protective barrier against excess fluid accumulation in the heart. - It helps maintain optimal cardiac filling and function. - Lubrication and protection from infection: - The pericardial cavity contains a small amount of fluid that lubricates the heart's movement, reducing friction. - It also provides a protective barrier against infections that may affect the heart. - Relationship to the phrenic nerves: - The pericardium is closely related to the phrenic nerves, which innervate the diaphragm. - Irritation of the pericardium can cause referred pain to the shoulder or upper abdomen. - Problems associated with fluid accumulation in the pericardial sac: - Excessive fluid accumulation (pericardial effusion) can compress the heart, leading to cardiac tamponade. - Cardiac tamponade is a life-threatening condition that impairs cardiac function and requires urgent intervention. ### Coronary Circulation: - Supply of blood to the myocardium: - The coronary circulation provides oxygen and nutrients to the heart muscle (myocardium). - Without adequate blood supply, the heart's function is compromised. - Coronary arteries and their distribution: - The right coronary artery (RCA) supplies the right atrium and right ventricle. - It also gives rise to the SA nodal artery and the posterior descending artery (PDA). - The left coronary artery (LCA) supplies the left atrium and left ventricle. - It branches into the left anterior descending artery (LAD) or anterior interventricular artery and the left circumflex artery (LCX). - Coronary dominance: - Coronary dominance refers to the artery that gives rise to the PDA. - Right dominance occurs when the RCA supplies the PDA. - Left dominance occurs when the LCX supplies the PDA. - Co-dominance is when both the RCA and LCX contribute to the PDA's blood supply. - Role of cardiac veins: - Cardiac veins drain deoxygenated blood from the myocardium. - The great cardiac vein, middle cardiac vein, and small cardiac vein are important cardiac veins. - They collect blood and drain it into the coronary sinus, which then empties into the right atrium. Key Concepts ------------ 1. Pericardium: - The pericardium is a protective sac that surrounds and supports the heart. - It limits the heart's motion and prevents overfilling. - The pericardial cavity contains a small amount of fluid for lubrication and protection from infection. - It is closely related to the phrenic nerves, and problems with the pericardium can cause referred pain. - Fluid accumulation in the pericardial sac can lead to cardiac tamponade, a serious condition requiring immediate attention. 2. Coronary Circulation: - The coronary circulation supplies the heart muscle (myocardium) with oxygen and nutrients. - The right coronary artery (RCA) supplies the right atrium and ventricle, SA nodal artery, and PDA. - The left coronary artery (LCA) supplies the left atrium and ventricle, LAD, and LCX. - Coronary dominance refers to the artery that supplies the PDA, which can be right, left, or co-dominant. - Cardiac veins collect deoxygenated blood from the myocardium and drain it into the coronary sinus and then the right atrium. ---------------------------------------------------------------------------------------------------------------------------- Additional Resources -------------------- ### Coronary Circulation ------------------------------------------------------------------------ Recap and Conclusion -------------------- In this lecture, we covered the core content of cardiovascular (CVS) anatomy, focusing on the structure and function of the heart, major blood vessels, pericardium, and coronary circulation. We discussed the anatomy of the heart, its position, external features, and the course of blood flow into and out of the heart. We also explored the pericardium, its functions, relationship to the phrenic nerves, and problems associated with fluid accumulation. Furthermore, we learned about the main vessels comprising the coronary circulation, including the coronary arteries and their branches. Lastly, we discussed coronary dominance and the role of cardiac veins in venous drainage of the heart. \#complete