Anatomy of Cardiovascular System.docx

Heart Within the pericardium In the “middle mediastinum” Central, between the pleural cavities Heart sits on the diaphragm and apex of heart lying displaced to the left Apex = found in the 5th intercostal space in mid-clavicular line Orientation Tipped pyramid Diaphragmatic surface Most of this...

Heart Within the pericardium In the “middle mediastinum” Central, between the pleural cavities Heart sits on the diaphragm and apex of heart lying displaced to the left Apex = found in the 5th intercostal space in mid-clavicular line Orientation Tipped pyramid Diaphragmatic surface Most of this surface is the LV Anterior Surface = RV Pulmonary Surfaces (facing the lungs) On the right = RA On the left = LA and LV ( a bit of both) Pericardium Structure Heart is surrounded by pericardium Serous Pericardium Parietal Visceral (epicardium) The other layer of heart itself Fibrous pericardium External to the parietal pericardium Very strong fibrous layer of connective tissue Firmly attached to diaphragmatic over the region of central tendon Also, attaches to sternum Continuous with tunica adventitia of great vessels Functions Anchors – maintains position of heart Prevent over-filling – done by inflexible fibrous pericardium Lubrication Protection Blood flow through the heart Double pump Oxygenated (left) Deoxygenated (right) RA – deoxygenated blood comes in from superior and inferior vena cava and coronary sinus Blood moves through the RA valve (tricuspid) into RV Blood moves through pulmonary valve into pulmonary trunk, which splits into left and right pulmonary arteries – off to the lungs Oxygenated blood returns via pulmonary veins into LA Blood flows through LA valve (bicuspid) into the LV LV contracts and blood flows through aortic valve and out into aorta for distribution around body Valves to prevent back-flow Right atrioventricular valve (tricuspid) Pulmonary valve Left atrioventricular valve (bicuspid/mitral) Aortic valve Aortic and pulmonary valves = semilunar Firmly closed when ventricles relax and end up catching the blood that would pool, stopping it from flowing back into ventricle But it is pushed open by blood leaving the ventricle during systole or during ventricular contraction Atrioventricular valves = flexible leaflets 3 on the right = tricuspid 2 on the right = bicuspid These are anchored to the walls of the ventricles by these chordae tendineae that attach to these papillary muscles When ventricle contracts, the valve blocks blood from flowing back towards the atrium The papillary muscles hold strong, stopping the valve from pro-lapsing towards the atrium Heart Valves = Heart Sounds Lub-dub sounds = closing heart valves Heart Orientation and Heart Sounds Purple dot (apex of heart = 5th intercostal space in mid-clavicular line) Mitral valve/left atrioventricular valve sounds Green dot (along same line as purple, but closer to sternum) Listen to sound of right atrioventricular valve (tricuspid) Blue and orange 2nd intercostal space on either side of sternum Listen to aortic (orange, right) and pulmonary valves (blue, left) Right Atrium Auricle/appendage Pectinate muscles Contribute to atrial contraction Fossa Ovalis Oval shaped depression Caval openings Coronary sinus opening Right Ventricle AV orifice Opening of atrium and ventricle AV valve (tricuspid) IV (intraventricular) septum Wall between LV and RV Chordae tendineae Strings that attach leaflet of valves to papillary muscles in the walls of ventricles Papillary muscles Trabecular carnae Ridges of muscles in walls of ventricles Pulmonary valve Smooth path at the outlet for blood that is leaving via pulmonary trunk Left Atrium Auricle/appendage (label 1) Pectinate muscles Fossa Ovalis (label 5) During foetal development it is open for a shortcut for blood to go between RA + LA Left Ventricle Chordae tendineae Papillary muscles Trabeculae carnae (label 8 in above diagram) Aortic valve Thicker wall than RV Heart features – Embryonic Remnants Foramen Ovale Fossa ovalis When fossa ovalis is open during foetal development – its called foramen Ovale Ductus arteriosis Ligamentum arteriosum Another shortcut in foetal development that blood can take is between pulmonary trunk and arch of aorta In adult, its closed (shown by big red arrow below) and its called ligamentum arteriosum But when opened in foetal life it’s called ductus arteriosis Coronary Arteries Blood supply to the heart Arise from the aortic sinuses, just superior to the aortic valve They fill when valve is closed, and blood is pooling in the valve They are not filling during the time of ventricular systole when blood is rushing by Arrangement highly variable Functional end arteries Nodal branch – supplies the sinoatrial (SA) node Another nodal branch near the posterior intraventricular branches Diagram below is the depth we need to learn Need to know! For the right coronary artery 2 nodal branches Marginal branch Usually gives rise to posterior interventricular branch Left coronary artery Anterior interventricular branch This is very often called left anterior descending artery Marginal branch Circumflex branch Which runs around the posterior/diaphragmatic surface and can contribute to giving blood supply to LV Venous drainage of the heart Venous drainage parallels the main arteries Small cardiac veins Medium (in the middle of the heart) cardiac veins In parallel to posterior interventricular artery Great cardiac veins Runs in parallel with left anterior descending artery (anterior interventricular branch of left coronary artery) All 3 of these cardiac veins drain into a big one across the back called coronary sinus Coronary Sinus – large vessel that runs posterior turning diaphragmatic surface between atria and ventricles It ultimately opens up into RA Cardiac Skeleton Heart is not all muscle, there’s an important connective tissue = fibrous skeleton Functions of this is : Anchors the valve cusps Prevents over-dilation of the valve openings Point of insertion of bundles of heart muscle Electrical insulation Conducting system SA node = natural pacemaker Releases electrical stimuli at a regular rate SA node is a group of cells located in RA close to opening of superior vena cava Releases stimuli which are transmitted to LA and RA This propagates through atria to AV node (in RA) in interatrial septum near opening of coronary sinus AV node transmits impulse to ventricles with a delay because of fibrous skeleton Path is via bundle of his Bundle branches right and left in interventricular septum Purkinje fibres fan out and triggers ventricular contraction strategically from the bottom moving blood upwards towards the outflow tracts SA – AV node – delay – AV – bundle of his – Purkinje fibres Autonomic regulation of heart Heart rate regulated by ANS Parasympathetic Slows heart rate, it’s from the vagus nerve Sympathetic Increases heart rate contractility Courses of Vagus and Phrenic nerves Left vagus nerve arrives at arch of aorta Forms networks or plexuses to regulate heart and lung functioning Phrenic nerve runs in front of root of lung in close relationships with fibrous pericardium running down to diaphragm Vagus nerve is running behind root of lung It has a branch called left recurrent laryngeal (scooping underneath arch or aorta) Rest of vagus nerve carries on ultimately hugging the oesophagus contributing the “rest + digest” Sympathetic Chain/trunk Ganglionated cord Paravertebral ganglia Effects on heart = increase rate and contractility Effects on lung (airway and vasculature) = vasoconstrict and bronchodilate Short pre-ganglionic From lateral horn of T1-L2 into the chain) Long post-ganglionic From chain to the organ The Great Vessels Relationship with trachea, oesophagus, nerves … Branches of the arch of the aorta Brachiocephalic trunk Right common carotid and right subclavian Left common carotid Left subclavian Blood return to the heart Deoxygenated blood from heart, neck, upper limb and thoracic wall returns to heart via superior vena cava Which is formed by the joining of subclavian vein and internal jugular vein – these come together to form the brachiocephalic vein Brachiocephalic vein on left and right come together to form superior vena cava Azygous vein draining the posterior intercostal veins also travels up over the root of lung and joins the superior vena cava before it opens up into RA of heart Inferior vena cava Coronary sinus Blood flow to and from heart Inferior vena cava Returning blood from abdomen and lower limbs Coronary sinus Biggest vein in coronary system Lies in groove between the atria and ventricles on posterior turned diaphragmatic surface of the heart The Cardiovascular System Distribution to the body Cardiovascular system – encompasses the heart, capillaries, arteries and veins Circulatory system – encompasses all of the cardiovascular system AND LYMPHATICS Arteries Thicker Hold their structure Veins Thinner relative to the lumen size Therefore, it can end up collapsing often in our specimens Blueish colour Large elastic conducting arteries (e.g. aorta) Strong wall but can be compromised due to aneurism Medium muscular distributing arteries Small arteries (arterioles) > capillaries Small veins (venules) Veins Pulmonary system – low pressure Pulmonary arteries Don’t have same muscular walls relative to pulmonary veins that you would see in systemic circulation