Normal Cardiac Anatomy

Abstract

It is axiomatic that understanding of abnormal anatomy requires a thorough knowledge of normal findings. Nowadays, this knowledge should be based on the appreciation of the location of the heart within the chest, since the basic rule of anatomy is that all structures should be described relative to the anatomical position. The discrepancy between the planes of the heart and the planes of the body should not detract from the importance of abiding by this rule. Having understood the discrepancies between the axes, it is then important to appreciate that the so-called right chambers are anterior to their allegedly left-sided counterparts, with the left atrium being the most posterior of the cardiac chambers. The atriums possess venous components, appendages, and vestibules, being separated by the septum. The left atrium also has an obvious body. The ventricles are best assessed on the basis of possessing inlet, apical trabecular, and outlet components. The arterial trunks spiral as they extend from the base of the heart into the mediastinum. The cardiac valves are best considered in terms of atrioventricular and arterial complexes, with the leaflets being the working units of all the valves. The atrioventricular valves also have a well-formed tension apparatus, while the arterial valvar leaflets are supported by the valvar sinuses. There are atrial, atrioventricular, and ventricular septal structures. Accounts of the fibrous skeleton are markedly exaggerated, with the so-called central fibrous body being the best formed fibrous element within the heart. This part is perforated by the atrioventricular conduction axis, with the cardiac impulse being generated by the sinus node and slowed in the atrioventricular node. The major coronary arteries and veins occupy the atrioventricular and interventricular grooves, with two coronary arteries arising from the aortic root and most of the veins draining to the coronary sinus located within the left atrioventricular groove.