The Heart PDF

the heart Prepared By Prof. Amjad Al-Shatarat Department of Biomedical Sciences Faculty of Medicine Aqaba Medical sciences university 2024 1  The normal heart contracts rhythmically at about 70 to 90 beats per minut...

the heart Prepared By Prof. Amjad Al-Shatarat Department of Biomedical Sciences Faculty of Medicine Aqaba Medical sciences university 2024 1  The normal heart contracts rhythmically at about 70 to 90 beats per minute in the resting adult.  MEDIASTINUM The mediastinum is a broad central partition that separates the two laterally placed pleural cavities. The mediastinum extends: from the sternum to the bodies of the vertebrae; and from the superior thoracic aperture to the diaphragm  The Pericardium The pericardium is a fibroserous sac surrounding the heart and the roots of the great vessels 1-The fibrous pericardium is a tough connective tissue outer layer 2- The serous pericardium is thin and consists of two parts: A-The parietal layer B- The visceral layer (epicardium) The narrow space created between the two layers of serous pericardium, containing a small amount of fluid, is the pericardial cavity Pericarditis Pericarditis is an inflammatory condition of the pericardium  Heart The heart is a hollow muscular organ that is somewhat pyramid MYOCARDIUM shaped lies within the pericardium in the mediastinum. The walls of the heart are composed of : ENDOCARDIUM 1-cardiac muscle, the MYOCARDIUM WHICH is covered externally with serous pericardium, the EPICARDIUM and lined internally with a layer of endothelium, the ENDOCARDIUM EPICARDIUM  Surfaces of the Heart The heart has three surfaces: 1- Sternocostal (anterior) 2-Diaphragmatic (inferior) 3- A base (posterior) The base of the heart, or the posterior surface, is formed mainly by the left atrium, The apex of the heart, formed by the left ventricle, is directed downward, forward, and to the left It lies at the level of the fifth left intercostal space, 3.5 in. (9 cm) from the midline. important  Grooves on its (heart) external surfaces The anterior interventricular sulcus is on the anterior surface of the heart Anterior view  Posterior view The coronary sulcus circles the heart, separating the atria from the ventricles The posterior interventricular sulcus is on the diaphragmatic surface of the heart Chambers of the Heart The heart is divided by vertical septa into four chambers: 1-the right and left atria 2- the right and left ventricles.  1-Right Atrium The right atrium consists of a main cavity and a small outpouching, the auricle Openings into the Right Atrium 1-The superior vena cava : 2-The inferior vena cava 3-The coronary sinus 4- The right atrioventricular orifice is guarded by the tricuspid valve 2-Right Ventricle The right ventricle communicates with 1- The right atrium through the atrioventricular orifice 2-The pulmonary trunk through the pulmonary orifice As the cavity approaches the pulmonary orifice it becomes funnel shaped, at which point it is referred to as the infundibulum. Its internal structure shows several internal projecting ridges formed of muscle bundles known as trabeculae carneae. An example of trabeculae carneae is the papillary muscles, It is attached by their bases to the ventricular wall while their apices are connected by fibrous chords (the chordae tendineae) to the cusps of the tricuspid valve  3-Left Atrium consists of a main cavity and a left auricle. the fibrous pericardium separates it from the esophagus Openings into the Left Atrium 1-The four pulmonary veins (two from each lung, 2-The left atrioventricular orifice is guarded by THE MITRAL VALVE 4-Left Ventricle The left ventricle communicates with 1- The left atrium through the atrioventricular orifice 2- The aorta through the aortic orifice The walls of the left ventricle are three times thicker than those of the right ventricle. The pulmonary valve guards the pulmonary orifice and consists of The aortic valve guards the aortic orifice three semilunar cusps.  The mitral valve guards the left atrioventricular orifice It consists of two cusps. The tricuspid valve  guards the right atrioventricular orifice  consists of three cusps The left coronary artery  Most !blood from the heart wall drains into the right atrium through THE CORONARY SINUS tributaries of the coronary sinus. GREAT CARDIAC VEIN SMALL CARDIAC VEINS MIDDLE CARDIAC VEINS  Nerve Supply of the Heart The heart is innervated by sympathetic and parasympathetic fibers of the autonomic nervous system via the cardiac plexuses arteries. Activation of sympathetic nerves results in cardiac acceleration, increased force of contraction of the cardiac muscle, and dilatation of the coronary arteries. Activation of the parasympathetic nerves results in a reduction in the rate and force of contraction of the heart and a constriction of the coronary