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Anatomy (Fach) / Anatomy (Cardiac system) (Lektion)
- External anatomy + Pericardium 1. External anatomy a) Grooves - anterior and posterior: coronary sulcus/groove/atrioventricular groove - anterior interventricular groove - posterior interventricular groove b) Great vessels and chambers - Right ventricle: pulmonary trunk/arteries - Left ventricle: Aorta - Right atrium: SVC, IVC, coronary sinus, anterior cardiac veins - Left atrium: left and right pulmonary veins 2. Pericardium a) Fibrous pericardium - attaches the heart to the adjacent structures to stabilise it: roots of the great vessels, central tendon of diaphragm, sternum b) Serous pericardium - lines the fibrous pericardium and consists of 2 layers: --> visceral layer - adherent to the surface of the heart --> partietal layer - lines the fibrous pericardium - in between the layers is the pericardial cavity filled with a fluid (lubricant for constantly moving heart) secreted by simple squamous epithelium
- Cardiac chambers + Valves 1. Valves a) Atrioventricular valvs - tricuspid valve (between right atrium and ventricle) - bicuspid valve/mitral valve (between left atrium and ventricle) b) Pulmonary valve - semilunar, in pulmonary trunk c) Aortic valve - semilunar, in aorta (only valve in arteries!) --> all valves are attached to papillary muscles via chordae tendinae which place tension on the valves to prevent regurgitation of blood 2. Chambers a) Right atrium - auricle overlapping the pulmonary trunk - rough and smooth part seperated by a shallow external groove (sulcus terminalis) and an internal ridge (crista terminalis) --> between SVC and IVC - fossa ovalis in interatrial septum (remnant of foramen ovale) - opening of SVC and IVC, opening of coronary sinus - atrioventricular valve (tricuspid) b) Left atrium - rought and smooth part: rough part corresponds to the auricle and smooth part formed by the incorporation of the 4 pulmonary veins - opening of 4 pulmonary veins - atrioventricular (mitral) valve c) Right ventricle - Interventricular septum bulging into the right ventricle - pulmonary valve (opening of pulmonary trunk) d) Left ventricle - circular and more muscular than RV - aortic valve - aorta and the 3 aortic sinuses
- Microanatomy of the heart 1. Epicardium (tunica adventitia) - also called visceral pericardium (inner layer of pericardium) - contains fibroelastic CT, blood vessels, lymphatics, adipose tissue 2. Myocardium (tunica media) - cardiac muscle, loose CT and capillaries a) Purkinje fibres - specialised conducting cells composed of electrically excitable cells larger than cardiomyocytes --> fewer myofibrils, more mitochondria, glycogen storage, fast AP conduction b) Intercalated discs - connect individual cardiomyocytes to work as a synctium using cell junctions 3. Endocardium (tunica intima) - covers atria, ventricles and lines heart valves
- Coronary vasculature 1. Arterial blood supply - two coronary arteries supply the heart, arising from the ascending aorta a) Right coronary artery - originates from anterior aortic sinus - right coronary artery --> right marginal branch and posterior interventricular branch --> supplies right atrium, right ventricle, bottom of left ventricle, back of septum b) Left coronary artery - arises from the left posterior aortic sinus - left coronary artery --> anterior interventricular branch, circumflex branches and left marginal artery --> supplies left atrium and ventricle, front of septum 2. Venous drainage - veins which accompany the coronary arteries which drain into the coronary sinus --> drains into the right atrium - small anterior cardiac veins (drain blood from the wall of the right ventricle) --> open in right atrium - venae cordis minimae which drain blood from the wall of the heart --> open in chambers of the heart
- Fibrous skeleton - dense collagen network around the junction between the atria and the ventricles and the great arterial openings 1. Functions - electrophysiological discontinuity between atrial and ventricular myocardium - mechanical attachment for ventricular myocardium - attachment for aortic and atrioventricular valves a) Tricuspid valve annulus (CT) b) Mitral valve annulus (CT)
- Innervation of the heart 1. Way of conduction - SAN (right atrium) --> AVN (interartrial septum) --> Atrioventricular bundle/Bundle of His (atrioventricular junction) --> bifurcation into left and right branches (interventricular septum) --> Purkinje fibres (myocardium) 2. Nerve supply a) Visceral affarents - Heart: pass through the cardiac plexus and enter the spinal cord at T1-4 --> stimulated by ischaemia - Aorta and great vessels: parasympathetic nerves pass within the vagus nerve --> stimulated by changes in blood pressure - Pericardium: affarent fibres from the serous pericardium carried in the phrenic nerve (C3-5)(somatic nerve), affarent fibres from the visceral pericardium carried in autonomous fibres b) Visceral Efferents - Sympathetic: Preganglionic fibres from T1-5 --> synapse in sympathetic chain --> postganglionic cardiac nerves --> cardiac plexus --> atria, ventricles, coronary arteries - Parasympathetic: Vagus nerve
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