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Anatomy (Fach) / Cardiac system (Lektion)
- External anatomy and Pericardium 1. External anatomy - heart is cone shaped: apex of the cone lies anteriorly to the left, the base lies posteriorly to the right a) Chambers - Right atrium --> superior and inferior vena cava, anterior cardiac veins, coronary sinus - Left atrium --> left and right pulmonary veins - Right ventricle --> pulmonary artery - Left ventricle --> Aorta b) Sulci - Coronary sulcus/coronary groove/atrioventricular groove (seperates atrium from ventricle) - Anterior and posterior interventricular groove (seperates ventricles) --> interventricular septum c) Auricular appendices (auricles) - the left and right atria have appendages projecting forward on either side of the great arteries 2. Pericardium - tough sac enclosing the heart, consists of 2 layers: a) Fibrous pericardium - outermost layer, attached to te great vessels, posterior surface of sternum and central tendon of diaphragm b) Serous pericardium - lines the fibrous pericardium and consist of the visceral layer and the parietal layer --> in between lies the pericardial cavity filled with pericardial fluid (lubricant) --> both layers are continuous with each other around the roots of the great vessels --> visceral layer is also called epicardium (part of the heart wall)
- Cardiac chambers (Atria + ventricles + Muscles) 1. Atria - right and left atria seperated by interatrial septum (fossa ovalis --> remnant of the foramen ovale) a) Right atrium - Sulcus terminalis (external groove) and crista terminalis (internal vertical ridge) seperating the rough and smooth parts --> superior to inferior vena cava - thin wall (receives blood from vena cava) - Superior and inferior vena cava and the coronary sinus drain inside it - Atrioventricular valve (tricuspid valve) b) Left atrium - rough part (auricle) and smooth part (incorporation of the 4 pulmonary veins) - 4 pulmoanry veins drain inside it - Mitral valve (bicuspid valve) 2. Ventricles - have thick muscular walls and enlarged muscular ridges (papillary muscles) to which the chordae are attached --> place tension on them - seperated by the interventricular septum a) Right ventricle - Rough inflow portion (muscular ridges) and smooth outflow portion (opening of pulmonary trunk) - Pulmonary artery - pulmonary valve (three semilunar cusps) b) Left ventricle - thicker wall - Aortic opening, aortic sinuses (left and right coronary arteries) - Aortic valve (three semilunar cusps) 3. Muscles - left and right pectinate muscles in left and right atrium --> can stretch and improve atrial volume - Atrial musculature - Ventricular musculature
- Microanatomy of the heart 1. Myocardium - 2 layers: a) Cardiac muscle - contain intercalated discs: connect individual cardiomyocytes to work as a synactium --> contain cell junctions (desmosomes, gap junctions, fascia adherens) b) Purkinje fibres - specialised conducting fibres composed of electrically excitable cells larger than cardiomyocytes --> carry AP from SAN --> bundle of His --> bundle branches --> Purkinje fibres --> myocardium --> CT fibres (collagen) in between (contains capillaries)
- Microanatomy: Layers of the heart 1. Epicardium/Visceral pericardium - tunica adventitia - fibroelastic CT, blood vessels, lymphatics, adipose tissue - simple squamous epithelium (mesothelium) 2. Myocardium - tunica media - cardiac muscle fibres, loose endomysial CT, capillaries 3. Endocardium - tunica intima - lines atria, ventricles and covers heart valves
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