L18- Cardiovascular System.pdf

L18- Cardiovascular System Dr.Pugazhandhi Bakthavatchalam Assistant Professor of Anatomy and Physiology, AUACAS, AUA LEARNING OUTCOMES At the end of this session the student would be able to: Gross anatomy of the heart Valves of the heart Fibrous skeleton of the heart Fetal...

L18- Cardiovascular System Dr.Pugazhandhi Bakthavatchalam Assistant Professor of Anatomy and Physiology, AUACAS, AUA LEARNING OUTCOMES At the end of this session the student would be able to: Gross anatomy of the heart Valves of the heart Fibrous skeleton of the heart Fetal Circulation 17-Sep-24 2 LOCATION AND POSITION OF THE HEART Conical muscular organ situated in middle mediastinum within the pericardium  LOCATION Superior surface of diaphragm Left of the midline Anterior to the vertebral column, posterior to the sternum  WEIGHT- 300g in males, 250g in females  SIZE- Approximately the size of your fist 17-Sep-24 3  POSITION OF THE HEART  Heart is obliquely placed behind the body of the sternum and the adjoining parts of the costal cartilages  One third of the heart lies to the right and two thirds to the left of the median plane 17-Sep-24 4  SURFACE ANATOMY OF THE HEART  Upper border is marked by a straight line joining: i. A point at the lower border of second left costal cartilage about 1.3cm from the sternal angle to ii. A point at the upper border of third right costal cartilage 0.8cm from the sternal marigin  Lower border is marked by a straight line joining i. A point at the lower border of 6th right costal cartilage 2cm from the sternal margin to ii. A point at the apex of the heart in the left 5th intercostal space 9cm from the midsternal line 17-Sep-24 5  SURFACE ANATOMY OF THE HEART  Right border is marked by a line slightly convex to the right joining the right ends of the upper and lower border  Left border is marked by a line convex to the left joining the left ends of the upper and lower border 17-Sep-24 6  EXTERNAL FEATURES OF THE HEART  Heart has Chambers Grooves/ Sulci Surfaces Borders Apex Base  CHAMBERS OF THE HEART: 4 Chambers: Two atria (right atrium & left atrium) Two ventricles (right & left) The atria lie above and behind the ventricles 17-Sep-24 7  GROOVES/SULCI OF THE HEART 1. Atrioventricular groove/Coronary sulcus (right & left) - On the surface of the heart separate the atrium from the ventricles 2. Interventricular groove/Sulcus (anterior & posterior) - Separates the two ventricles from each other 3. Interatrial goorve/Sulcus: - Separates the two atria from each other 17-Sep-24 8  GROOVES/SULCI OF THE HEART 1. ATRIOVENTRICULAR GROOVE: a. Right atrioventricular groove: Overlapped anteriorly by the ascending aorta and pulmonary trunk Separates right atrium from right ventricle b. Left Atrioventricular groove (left coronary sulcus) Separates left atrium from left ventricle 17-Sep-24 9  GROOVES/SULCI OF THE HEART 2. INTERVENTRICULAR GROOVE: a. Anterior interventricular groove: - Nearer to the left margin of the heart - Lower end of the groove separates the apex from the rest of the inferior border of the heart b. Posterior interventricular groove: - Situated on the inferior (diaphragmatic) surface of the heart The two interventricular grooves meet at the inferior border of the heart near the apex 17-Sep-24 10  GROOVES/SULCI OF THE HEART 3. INTERATRIAL GROOVE: - Faintly visible posteriorly while hidden by the aorta and the pulmonary trunk anteriorly 17-Sep-24 11  APEX OF THE HEART  Formed entirely by the left ventricle  Directed downwards, forwards and to the left  Situated in the left 5th intercostal space 9cm lateral to the mid sternal line just medial to the midclavicular line 17-Sep-24 12  BASE OF THE HEART  Also called as the posterior surface  Formed mainly by the left atrium and a small part of right atrium  Left atrium shows the openings of four pulmonary veins  Right atrium receives the superior and inferior venacava 17-Sep-24 13  BORDERS OF THE HEART  Upper border  Lower border  Right border  Left border UPPER BORDER: - Slightly oblique and formed by the two atria - Chiefly by the left atrium RIGHT BORDER: - More or less vertical - Formed by the right atrium 17-Sep-24 14  BORDERS OF THE HEART LOWER BORDER: - Nearly horizontal - Formed mainly by the right ventricle - A small part near the apex by the left ventricle LEFT BORDER: - Oblique and curved - Formed mainly by the left ventricle - Partly by the left auricle 17-Sep-24 15  SURFACES OF THE HEART  Anterior/ sternocostal  Inferior/ diaphragmatic  Left surface  Posterior surface/ Base  ANTERIOR/ STERNOCOSTAL SURFACE: - Formed mainly by the right atrium and right ventricle - Partly by the left ventricle and left auricle  INFERIOR/DIAPHRAGMATIC SURFACE: - Rest on central tendon of the diaphragm - Formed by left ventricle on the left 2/3rd and right ventricle on the right 17-Sep-24 1/3rd 16  SURFACES OF THE HEART  LEFT SURFACE: - Formed mostly by the left ventricle - Partly on its upper end by the left auricle 17-Sep-24 17  RIGHT ATRIUM  The right upper chamber of the heart  Receives venous blood from the whole body through superior and inferior venacava  Pumps the venous blood into the right ventricle through right atrioventricular or tricuspid opening  EXTERNAL FEATURES: - Upper end is prolonged to form the right auricle - Sulcus terminalis: a shallow vertical groove along the right border, extends from SVC to IVC 17-Sep-24 18  RIGHT ATRIUM - Sulcus terminalis is produced by crista terminalis (a muscular ridge in the interior) - Upper part of sulcus terminalis contains SA (sinu atrial) node (pacemaker of heart) TRIBUTARIES/INLETS OF THE RIGHT ATRIUM: a. Superior venacava b. Inferior venacava c. Coronary sinus d. Anterior cardiac veins e. Venae cordis minimi (Thebesian veins) 17-Sep-24 19  INTERIOR OF RIGHT ATRIUM DIVIDED INTO THREE PARTS: a. Smooth posterior part (sinus venarum) b. Rough anterior part (pectinate part including the auricle c. Interatrial septum 17-Sep-24 20 Rough anterior part CRISTA TERMINALIS MUSCULI PECTINATI  Interior SMOOTH PART ROUGH PART INTERATRIAL SEPTUM Smooth posterior part SUPERIOR VENACAVA THEBASIAN VEIN OPENINGS CORONARY SINUS INFERIOR VENACAVA  SMOOTH POSTERIOR PART Shows the openings of: 1. Superior venacava at the upper end 2. Inferior venacava at the lower end - guarded by a valve of inferior venacava (Eustachian valve) - during embryonic life Eustachian valve guides the inferior veancaval blood to the left atrium through the foramen ovale 3. Coronary sinus - opens between the opening of inferior venacava and the right atrioventricular orifice - this opening is guarded by valve of coronary sinus 4. The venae cordis minimi are small veins that open into all the four chambers 17-Sep-24 24  ROUGH ANTERIOR PART : Has transverse muscular ridges- Musculi pectinati (appear as teeth of a comb) INTERATRIAL SEPTUM: Fossa ovalis: - shallow saucer shaped depression in the lower part - represents the site of embryonic septum primum Annulus fossa ovalis/ limbus fossa ovalis: - margin of the fossa ovalis - represents the free edge of septum secondum 17-Sep-24 25  Interatrial septum LIMBUS FOSSA OVALIS FOSSA OVALIS  RIGHT VENTRICLE Interior shows two parts: 1. Inflowing rough part (because of presence of muscular ridges called trabeculae carneae) 2. Outflowing smooth part/ Infundibulum - upper conical part of the right ventricle giving rise to pulmonary trunk These two parts are separated by a muscular ridge called as SUPRAVENTRICULAR CREST situated between the tricuspid (right atrioventricular orifice) and pulmonary orifice 17-Sep-24 27  Right ventricle Supraventricular crest Smooth part Rough part  Interior shows two orifices: a. Right atrioventricular orifice guarded by the tricuspid valve b. Pulmonary orifice guarded by the pulmonary valve Inflowing rough part has trabeculae carneae or muscular ridges of three types: a. Ridges (septomarginal trabeculae/ moderator band) b. Bridges c. Pillars (papillary muscles-3) 19.10.2015 29  Septal papillary muscle Chorda tendinae Moderator band Posterior Anterior Papillary muscle Papillary muscle Ridge Bridge  Pulmonary orifice Infundibulum Atrioventricular orifice  LEFT ATRIUM Receives oxygenated blood from the lungs through four pulmonary veins Pumps it to the left ventricle through left atrioventricular or bicuspid or mitral orifice guarded by the valve of the same name FEATURES: Septal wall shows fossa lunata Receives four pulmonary veins and few vena cordis minimi 32  LEFT VENTRICLE  FEATURES: The interior is divisible into two parts a. Lower rough part with trabeculae carneae b. Upper smooth part or aortic vestibule gives origin to ascending aorta  Interior shows two orifices: 1. Left atrioventricular/bicuspid/ mitral orifice guarded by bicuspid or mitral valve 2. Aortic orifice guarded by aortic valve  Has two well developed papillary muscles 17-Sep-24 33 INTERVENTRICULAR SEPTUM  Separates the right and left ventricle  Has upper thin membranous part and lower thick muscular part 17-Sep-24 34  VALVES OF THE HEART  Maintains the unidirectional flow of blood and prevents its regurgitation in the opposite direction  There are two pairs of valves in the heart a. A pair of atrioventricular valves b. A pair of semilunar valves - Right atrioventricular valve is known as tricuspid valve because it has 3 cusps - Left atrioventricular valve is known as bicuspid valve because it has two cusps - Semilunar valves include aortic and pulmonary valves both having 3 semilunar cusps Cusps are folds of endocardium strengthened by fibrous tissues 17-Sep-24 35 SURFACE MARKING OF THE CARDIAC VALVES 17-Sep-24 36 17-Sep-24 37 FETAL CIRCULATION  Circulation Before Birth FETAL CIRCULATION Before birth, blood from the placenta, about 80% saturated with oxygen, returns to the fetus by way of the umbilical vein On approaching the liver, most of this blood flows through the ductus venosus directly into the inferior vena cava, short-circuiting the liver A smaller amount enters the liver sinusoids and mixes with blood from the portal circulation After a short course in the inferior vena cava, where placental blood mixes with deoxygenated blood returning from the lower limbs, it enters the right atrium Here it is guided toward the oval foramen by the valve of the inferior vena cava, and most of the blood passes directly into the left atrium From the left atrium, where it mixes with a small amount of desaturated blood returning from the lungs, blood enters the left ventricle and ascending aorta.  Desaturated blood from the superior vena cava flows by way of the right ventricle into the pulmonary trunk. During fetal life, resistance in the pulmonary vessels is high, such that most of this blood passes directly through the ductus arteriosus into the descending aorta, where it mixes with blood from the proximal aorta. After coursing through the descending aorta, blood flows toward the placenta by way of the two umbilical arteries. The oxygen saturation in the umbilical arteries is approximately 58%. During its course from the placenta to the organs of the fetus, blood in the umbilical vein gradually loses its high oxygen content as it mixes with desaturated blood  REFERENCES Drake R.L., Gray’s Anatomy for Students, 2nd Edition, 2009, Churchill Livingstone Moore, Clinically Oriented Anatomy, 6th Edition, 2009, Lippincott Williams & Wilkins Standring, Gray’s Anatomy: The Anatomical Basis of Clinical Practice, 40thEdition, 2008 Johannes W Rohen, Color Atlas of Anatomy: A photographic study of the human body, 7th Edition, Lippincott Williams & Wilkins Kenneth S Saladin, Human Anatomy, 2nd Edition, 2008, McGraw-Hill Companies 17-Sep-24 41