Heart Anatomy Quiz

Heart Anatomy

• The heart is a four-chambered muscular pump
• It consists of the right atrium, left atrium, right ventricle, and left ventricle
• Both atria receive venous blood.
• The right ventricle pumps blood to the lungs, the left ventricle pumps blood to the systemic circulation.

Heart Position and Borders

• The heart lies obliquely in the thoracic cavity, with its long axis pointing downwards and to the left to the apex.
• Right border: right atrium
• Inferior border: mostly right ventricle and a small portion of the left ventricle.
• The apex is formed at the junction of the inferior and left borders.
• Left border: mostly left ventricle
• Anterior surface: mostly right ventricle, with right atrium on its right.
• Posterior surface is the base: made up of the left atrium with the four pulmonary veins.

The Right Atrium

• An elongated chamber lying between the superior and inferior vena cava (SVC and IVC)
• Forms the right border of the heart.
• Its lower end is formed by the orifice of the inferior vena cava.
• The upper end is prolonged as the right auricle, which overlies the commencement of the aorta.
• The myocardium forms pectinate muscles—a series of horizontal ridges in the right atrium.
• The interatrial septum forms the posterior wall of the right atrium and contains the fossa ovalis.
• The coronary sinus opens into the right atrium.

The Right Ventricle

• Projects to the left side of the right atrium.
• Separated from the right atrium by the atrioventricular groove, in which the right coronary artery runs.
• The walls contain a series of muscular ridges—the trabeculae carneae.
• Papillary muscles connect the ventricular wall to the cusps of the tricuspid valve.

The Tricuspid Valve

• Guards the right atrioventricular opening.
• Has three cusps: anterior, posterior, and septal.
• Cusps are attached by chordae tendineae to the papillary muscles, which prevent the cusps from inverting during ventricular contraction.

The Pulmonary Valve

• Separates the pulmonary conus from the pulmonary trunk.
• Includes three semilunar cusps.

The Left Atrium

• Forms the posterior surface or base of the heart, behind the right atrium.
• The cavity of the left atrium is smooth-walled, except for the auricle, which contains muscular ridges—musculi pectinati.
• Four pulmonary veins enter the left atrium symmetrically, one above the other on each side, without valves.

The Mitral Valve

• A bicuspid valve (with two cusps), allowing blood flow from the left atrium into the left ventricle during diastole.
• Named anterior and posterior.
• Chordae tendineae and papillary muscles are connected to the mitral valve.

The Left Ventricle

• Forms the apex of the heart; its walls are three times thicker than those of the right ventricle.
• Well-developed trabeculae carneae
• Has two papillary muscles (anterior and posterior), each connected to the chordae tendineae.

The Aortic Valve

• Guards the aortic orifice at the entrance to the ascending aorta.
• Has three semilunar cusps labeled right, left, and posterior.
• The closure of this valve contributes the A₂ component of the second heart sound (S₂).
• During ventricular systole, pressure rises in the left ventricle. When the pressure in the left ventricle exceeds the pressure in the aorta, the aortic valve opens.

The Ascending Aorta

• Immediately above the aortic orifice, the wall of the ascending aorta bulges to form the aortic sinuses of Valsalva.
• Three aortic sinuses exist: left, right, and posterior.
• The left aortic sinuses give rise to the left coronary artery.
• The right aortic sinuses give rise to the right coronary artery.
• No arteries arise from the posterior aortic sinus (non-coronary sinus).

The Conducting System

• Comprised of the sinoatrial node (SAN), atrioventricular node (AVN), atrioventricular bundle of His, right and left bundle branches, and Purkinje fibers (subendocardial).
• These structures are responsible for coordinating the electrical activity of the heart, leading to its rhythmic contractions.

The Inter-ventricular Septum

• The septum bulges into the right ventricle, leading to a circular shape of the LV lumen and a crescent shape for the RV lumen in cross-section.
• The upper part (membranous part) is thin and fibrous, while the lower part (muscular part) is thick and muscular.

Test your knowledge on the anatomy and position of the heart. This quiz covers the four chambers of the heart, their functions, and the heart's placement within the thoracic cavity. Assess your understanding of cardiac structures and their significance to systemic and pulmonary circulation.