Anatomy of the Heart PDF - MD2011

Anatomy of the Heart MD2011 A/Prof. Monika Zimanyi Department of Anatomy and Pathology School of Medicine and Dentistry James Cook University [email protected] Learning Objectives After attending this lecture, students will be able to: Describe the arrangement of the fibrous and serous layer...

Anatomy of the Heart MD2011 A/Prof. Monika Zimanyi Department of Anatomy and Pathology School of Medicine and Dentistry James Cook University [email protected] Learning Objectives After attending this lecture, students will be able to: Describe the arrangement of the fibrous and serous layers of the pericardium. Describe the surface markings of the heart based on its location and orientation in the thoracic cavity. Identify the major anatomical features of each chamber of the heart and explain their functional significance. Describe the structure and position of the atrioventricular and semilunar valves and describe their function in the prevention of reflux of blood during the cardiac cycle. Describe the structure and function of the fibrous skeleton of the heart. Describe the anatomical course of the spread of electrical excitation through the chambers of the heart. Describe the origin, course, and relationships of the great vessels. Name their major branches/tributaries and the structures they supply/drain. Apply your knowledge of the structure of the heart to the pathway of blood through the heart and into the pulmonary and systemic circulations. Mediastinum (pl. mediastina) The space between the two pleural spaces Contains all the structures in the thorax except the lungs and pleurae Extends from the superior thoracic aperture to the diaphragm (inferior thoracic aperture) Divided into superior and inferior mediastina by the sternal angle The pericardium divides the inferior mediastinum into 3 further subdivisions: anterior, middle & posterior pleural spaces occured by the lungs. boundaries, sternum and vetebral column. Middle Mediastinum Pericardium & heart Great vessels associated with the heart Superior and inferior vena cavae Pulmonary trunk (& arteries) Pulmonary vein outside pericaridum but included in Aorta the middle medistinum The R & L phrenic nerves Roots of the lungs Location of the Heart 2nd rib to 5th intercostal space Anterior to vertebral column Posterior to sternum Between the two pleural spaces Pericardium thick outtermost layer of the heart. The fibrous pericardium is a tough outer sac, which protects the heart against sudden over filling It is attached to the great vessels The base is fused to the central tendon stuck to the central tendon of the diaphragm Pericardium epicardium- on the viscera means on an organ (heart in thi case) The serous pericardium (parietal and visceral) produces serous fluid that enables the heart to beat in a relatively friction free environment fluid layer to help lubricate the heart Layers of the Heart Wall Epicardium = visceral pericardium! Myocardium = heart muscle Endocardium – continuous with endothelium of vessels myocardium endocaridum Layers of the Heart Wall Anderson, Smerup, Sanchez-Quintana, Loukas and Lunkenheimer (2009) The Three-Dimensional Arrangement of the Myocytes in the Ventricular Walls, Clinical Anatomy 22:64–76. Orientation of the Heart Apex = left ventricle Base = left and right atria Right border = right atrium Left border = left ventricle Anterior border = right ventricle Aortic arch SVC Pulmonary artery can see only because there is blood inside RA IVC LV RV penetrates diaphragm and into the heart apex Function of the Heart Delivery of deoxygenated blood to lungs = pulmonary circuit collects blood from all over the body Delivery of oxygenated blood to tissues and cells = systemic circuit Right Atrium (RA) Atrial appendage (auricle) - embryonic remnant of right atrium Fossa ovalis, formerly a foramen b/w two atria, to bypass pulmonary circuit during development Caval valve directs blood from RA to LA is used for embyronic development Coronary sinus – opening where venous blood from the heart enters the RA an opening in the atrium where thevenous blood comes to the heart from the heart Tricuspid valve – lies between RA and RV Pectinate muscles – muscles of the atrial wall Thin walls no point blood going to the lungs during development so the right atrium is going straight into the left atrium due to a foarmen, not fossa ovalis. Right Ventricle (RV) in the wall known as trabeculae carnae Trabeculae carnae – muscle of the ventricular wall Tricuspid valve Cusps (x3) Cordae tendinae tendon like structure, distally attach to capillaary muscles. Papillary muscles Moderator band = septomarginal trabecula (contain Purkinje fibers) Pulmonary valve – b/w RV and pulmonary trunk Medium thickness walls purkinje fibers which creates an action potential to the muscle it is attached to. Left Atrium (LA) Entrance of pulmonary veins (x4) Atrial appendage = auricle Bicuspid valve – lies between LA and LV Thin walls mitral valve Left Ventricle (LV) Mitral (bicuspid) valve Cusps (x2) Cordae tendinae Pappilary muscles Trabeculae carnae Aortic valve - b/w LV and aorta Thick, muscular walls cord like structure which anchors the valve to the papillary The Heart – Blood Flow SVC – superior vena cava brings deoxy blood from upper body IVC - inferior vena cava brings deoxy blood from lower body RA and LA are collecting chambers RV and LV are ejecting chambers so thicker wall than atria, but RV thinner than LV due to pressure differences PA – pulmonary arteries, which divide from the pulmonary trunk and go to lungs Aorta – largest artery, takes oxy blood to all of the body Heart Valves Function of ALL valves – allow one way flow of blood function by making sure blood flows in the right direction 4 valves: 2 x atrioventricular Tricuspid Bicuspid 2 x semilunar Pulmonary Aortic Atrioventricular Valves Atrioventricular valves (tricuspid and bicuspid): Have flaps/cusps/leaflets Have chordae tendinae – attach cusps to papillary muscles Have papillary muscles (muscular contraction prevents prolapse) Are active (use energy) AV Valve Function Valve opens during atrial contraction Ventricle fills with blood Ventricle contracts, blood is forced against AV valve cusps Papillary muscles contract, chordae tendinae tightened and prevent flaps from prolapsing into atria = AV valve is closed Semilunar Valves Semilunar valves (pulmonary, aortic) Have flaps/cusps/leaflets Have sinuses Are passive (closed by backflow of blood, no energy used) Semilunar Valve Function As ventricles contract, blood forcefully opens the semilunar valves As ventricles relax, blood flows back from the great vessels, fills the cusps, which forces them to shut As ventricles contract blood opens the semilunar valves, when the ventricle relaxxes the cusps shut. Fibrous Skeleton of the Heart Functions: Four rings of connective tissue to support valves Septum to divide two sides (incl. electrically) Allows for muscular attachment Support valves Divide septrum Nodes Muscle attachment Valves of the Heart in Diastole and Systole Anterior Left Right Ventricles contract ventricles relaxed causing greatvessels to flow back to stop blood flow. Posterior Conducting System of the Heart SA-> Located at base of SVC Sinoatrial (SA) node impulses to cause atria to contract Lies at base of SVC Generates impulses that will travel through the atria Ineratrial septum, above the tricuspid valve Atrioventricular (AV) node bundle of HIS. Right bundle surrounds RV Left Surrounds Lies in interatrial septum, above the contraction of both atria, then AV noves contract the tricuspid valve Leads to AV bundle (bundle of His) AV bundle divides and each branch will further divide to surround the ventricles Announcement Please wait for the announcement, it won’t take long.