Heart and its Chambers
View of the heart with its several chambers exposed and the vessels in connection with them. Labels: 1, the superior vena cava. 2, the inferior vena cava. 3. the chamber called the auricle. 4. the right ventricle. 5. the line marking the passage between the two chambers, and the points of attachment of one margin of the valve. 6. the septum between the two ventricles. 7. the pulmonary artery, arising from the right ventricle, and dividing at 8 into right and left, of the corresponding lungs. 9. the four pulmonary veins, bringing the blood from the lungs into 10, the left auricle. 11. the left ventricle. 12. the aorta, arising from the left ventricle, and passing down behind the heart, to distribute blood to every part of the system. Thus the blood moves in a double circle, one from the heart to the body, and from the body back to the heart, called the systemic circle; the other, from the heart to the lung, and from the lung back to the heart, called the pulmonic circle.