External Features of the Heart Lecture PDF

External features of the heart Prof. Dr. Abdelghany Hassan Abdelghany Professor of Anatomy and Embryology Faculty of Medicine, Alexandria University Heart Definition : A hollow muscular pump. Site : in the middle mediastinum. It lies opposite 2nd to 6th costal cartilages. It lies...

External features of the heart Prof. Dr. Abdelghany Hassan Abdelghany Professor of Anatomy and Embryology Faculty of Medicine, Alexandria University Heart Definition : A hollow muscular pump. Site : in the middle mediastinum. It lies opposite 2nd to 6th costal cartilages. It lies opposite T5 to T8. 1/3 of the heart lies to the right and 2/3 to the left of the median plane.  External features - It has 4 chambers : - 2 atria (right and left) separated by the interatrial septum. - 2 ventricles (right and left) separated by the interventricular septum.  External features - It is pyramidal. - The apex is formed completely by the left ventricle. It is directed downwards, forwards, to the left. - The base is formed mainly by the right atrium and slightly by the right atrium. It is directed backwards and to the right. External features - It has 3 surfaces : 1- sternocostal (anterior). 2- diaphragmatic (inferior). 3- posterior (base). - It has 4 borders : 1- right. 2- lower. 3- left. 4- upper.  Borders of the heart - Right border is formed by right atrium. - Left border is formed by the left ventricle and left auricle. - Lower border is formed by the right and left ventricles. - Upper border is formed by the 2 atria.  Sternocostal surface - It is related to body of the sternum, costal cartilage and anterior borders of lungs and pleura. - It is formed of : A. Atrial part : formed by the right atrium and left auricle. B. Ventricular part : 2/3 are formed by the right ventricle and 1/3 by the left ventricle.  Sternocostal surface - It shows 2 groves : 1- Anterior interventricular groove between the 2 ventricles. It gives passage to the anterior interventricular artery and great cardiac vein. 2- Atrio-ventricular or coronary grove (sulcus) between the atria and ventricles. It gives passage to coronary arteries.  Diaphragmatic surface - It rests on the diaphragm. It is formed by the 2 ventricles (2/3 by the left ventricle and 1/3 by the right ventricle). - It shows the posterior interventricular grove that gives passage to the posterior interventricular artery and middle cardiac vein.  Pericardium - It is the covering of the heart. - It is formed of : Outer fibrous pericardium. Inner serous pericardium : a. Parietal layer (lines the fibrous pericardium). b. Visceral layer (covers the heart). - The 2 layers are continuous around the great vessels of the heart. Pericardium - The layers of serous pericardium are separated by a fluid-filled cavity called the pericardial cavity. - Fibrous pericardium : - It covers serous pericardium. - 2 sterno-pericardial ligaments attach fibrous pericardium to the body of sternum. Pericardium - Functions : 1- protection of the heart. 2- prevents overfilling of the heart. 3- prevents friction between the heart and surroundings. Surface anatomy of the heart Point 1: left 2nd costal cartilage 1.5 inches from the middle line Point 2: right 3rd costal cartilage one inch from the middle line. Point 3: Right 6th costal cartilage ½ inch from the middle line. Point 4: Left 5th intercostal space 3.5 inches from the middle line.  Surface anatomy of the heart Point 1: left 2nd costal cartilage 1.5 inches from the middle line Point 2: right 3rd costal cartilage one inch from the middle line. Point 3: Right 6th costal cartilage ½ inch from the middle line. Point 4: Left 5th intercostal space 3.5 inches from the middle line.  Surface anatomy of the heart valves Pulmonary valve : left sternal margin opposite the 3rd costal cartilage. Aortic valve : left sternal margin opposite the 3rd intercostal space. Mitral valve : left sternal margin opposite the 4th costal cartilage Tricuspid valve : 4th intercostal space in the midline.  Test your self - True or false : 1. Apex of the heart is formed by both atria. F 2- Right border of the heart is formed by right atrium. T 3- Atrioventricular grove contains great cardiac vein. F 4- Pericardial cavity lies between the serous and fibrous pericardium. F  Test your self - What is the surface anatomy of mitral valve? A. 3rd costal cartilage at left sternal margin. B. 3rd intercostal space at left sternal margin. C. 4th costal cartilage at left sternal margin. D. 4th intercostal space in the midline. 4th costal cartilage at left sternal margin