Cardiovascular System Lecture 2 PDF

Cardiovascular system lecture 2 Mo Anatomy CVS ANATOMY Internal features of the heart Internal features of the heart Right atrium Post...

Cardiovascular system lecture 2 Mo Anatomy CVS ANATOMY Internal features of the heart Internal features of the heart Right atrium Posterior  Receives the openings of the SVC, IVC, and coronary sinus. Smooth Wall  A vertical ridge extending from the SVC opening to the IVC opening. Crista  Corresponds to the sulcus terminalis on the outer surface. Terminalis  Separates the smooth posterior wall from the rough Internal anterior wall. features Anterior Rough  Characterized by musculi pectinati (parallel muscular ridges) Wall and the crista terminalis.  Fossa Ovalis: An oval depression on the lower part of the Septal Smooth interatrial septum. Wall  Annulus Ovalis (Limbus Ovalis): A crescentic margin above and on both sides of the fossa.  The posterior wall has the following openings:  SVC (Right 3rd costal cartilage, no valve). Opening  IVC (Right 6th costal cartilage, ill-defined valve).  Coronary Sinus (located between the IVC and tricuspid orifice, with a well- developed valve) DR. ME Page | 1 CVS ANATOMY Internal features of the heart  Openings for anterior cardiac veins.  Vena Cordis Minimi.  Tricuspid Orifice and Valve (right atrioventricular opening). Left atrium Internal  Smooth compared to right atrium features  Small musculi pectinati present only in the left auricle 1) Four pulmonary veins (open in the upper part of posterior wall, no valve) Opening 2) Vena cordis minmi (open in the cavity of left atrium) 3) Mitral orifice & valve (left atrioventricular orifice) Right ventricle  Semilunar in cross section.  Divided into parts by the supraventricular crest: Outflowing  smooth, above the crest part  called infundibulum  below the crest, rough due to: Internal a) Trabeculae carne (muscular projections) features b) Three papillary muscles (anterior, septal and posterior). Inflowing part NB: Each muscle has one end attached to ventricular wall and other one attached to the cusps of the tricuspid valve via chordae tendineae DR. ME Page | 2 CVS ANATOMY Internal features of the heart c) Moderator band:  Muscular band connects the interventricular septum with anterior papillary muscle.  Function: conveys the right branch of AV bundle & prevents over distention of right ventricle 1) Tricuspid orifice & valve Opening 2) Pulmonary orifice & valve left ventricle  Its wall 3 times thicker  Circular in cross section  Divided into 2 parts: Outflowing  It is the upper part of left ventricle below the aortic orifice. part  Smooth & called aortic vestibule  Lower part of the left ventricle from mitral orifice to apex. Internal  Rough due to presence of: features a) Trabeculae carnae (more numerous) b) Papillary muscles: two large & thick Inflowing  Anterior (arises from anterior wall), part  posterior (arises from posterior wall) NB: Each muscle has one end attached to ventricular wall and other one attached to the cusps of the mitral valve via chordae tendineae 1) Mitral orifice & valve Opening 2) Aortic orifice & valve DR. ME Page | 3  CVS ANATOMY Internal features of the heart Feature Right Ventricle Left Ventricle Type of Blood Non-oxygenated Oxygenated Wall Thinner Thicker Cross Section Semilunar Circular Outflowing Part Called infundibulum Called aortic vestibule Papillary Muscles 3 (anterior, posterior, septal) 2 (anterior, posterior) Moderator Band Present Not present Communication with Tricuspid valve Mitral valve Corresponding Atrium Atrioventricular valves Semilunar valves  it includes tricuspid valve & mitral valve  It includes aortic & pulmonary valves  Each valve has three semilunar cusps which are attached to vessel wall Feature Tricuspid Valve Mitral Valve Feature Pulmonary Valve Aortic Valve Between right atrium & right Between left atrium & left Between right ventricle & Between left ventricle & Site ventricle ventricle Site pulmonary trunk ascending aorta Size 3 fingers 2 fingers Size 3 cm 2.5 cm Shape Oval Circular Shape Oval Circular Cusps 3 (anterior, posterior, septal) 2 (anterior, posterior) Cusps 3 (anterior, right, left) 3 (posterior, right, left) At the midline of the Behind the left half of the Behind the left 3rd costal On the left margin of the Surface sternum opposite 4th sternum opposite 4th costal Surface cartilage at the junction sternum opposite the left Marking intercostal space cartilage Marking with the sternum 3rd intercostal space DR. ME Page | 4 CVS ANATOMY Internal features of the heart Interventricular septum Function  Separates the two ventricles.  Curved, being concave towards the left ventricle and convex towards Description the right ventricle.  The septum is composed of two parts: Muscular  Thick, muscular, and forms the majority of the septum Part  Separates the right and left ventricles. Structure  Thin, fibrous, and constitutes a small area at the upper Membranous posterior part of the septum. Part  Separates the right ventricle and right atrium from the aortic vestibule. Conducting System of the Heart Function  Responsible for the initiation and transmission of excitation waves. Description  Consists of modified cardiac muscle fibers. Sinoatrial Node (SA  Located at the upper part of the sulcus terminalis. Node  Acts as the pacemaker of the heart. Atrioventricular Node  Situated at the lower part of the interatrial septum. (AV Node) Components Atrioventricular Bundle  Divides into right and left branches. (Bundle of His) Purkinje Fibers  Specialized fibers that spread the impulse throughout the ventricles. DR. ME Page | 5 CVS ANATOMY Internal features of the heart Surface anatomy of the heart Apex of the Heart Located in the left 5th intercostal space, 9 cm from the midline. Represented by an oblique line extending from left 3rd costal cartilage to Coronary Groove right 6th costal cartilage. Borders of the Heart A A point on the lower border of the left 2nd costal cartilage, 1.5 cm from the sternum. B A point on the upper border of the right 3rd costal cartilage, 1.5 cm from the sternum. C A point on the right 6th costal cartilage, 2 cm from the sternum. D A point on the left 5th intercostal space, 9 cm from the midline (apex). Upper Border Formed by two atria (mainly left atrium), represented by a horizontal line from A to B. Right Border Formed by the right atrium only, represented by a slightly convex line from B to C. Lower Border Formed in its right 2/3 by the right ventricle and its left 1/3 by the left ventricle, represented by a horizontal line from C to D. Left Border Formed mainly by the left ventricle, represented by a line convex from D to A. Valves of the Heart Pulmonary Valve (P) Lies behind the left 3rd costal cartilage at its junction with the sternum. Aortic Valve (A) Lies behind the left margin of the sternum opposite the left 3rd intercostal space. Mitral Valve (M) Lies behind the left half of the sternum opposite the left 4th costal cartilage. Tricuspid Valve (T) Lies behind the midline of the sternum opposite the 4th intercostal space. DR. ME Page | 6 CVS ANATOMY Internal features of the heart DR. ME Page | 7