It extends almost to the breastbone

It extends almost to the breastbone

It extends almost to the breastbone

In examining the heart itself it is necessary to recall that it lies in the anterior portion of the chest slightly to the left of the median line and that it extends from the third to the sixth rib. It extends almost to the breastbone, and a little more than half of the distance between the breastbone and the backbone. In contracting, it rotates slightly on its axis, so that the point of the heart, which lies below, is pressed against the left chest wall at a place immediately above the point of the elbow. The heart has in it four chambers two in the left and two in the right side. The upper chamber of the left side (left auricle) receives the blood as it comes from the lungs, passes it to the lower chamber of the left side (left ventricle), and from here it is sent with great force (for this chamber has very strong, thick walls) through the aorta and its branches (the arteries) to all parts of the body. The blood returns through the veins to the upper chamber of the right side (right auricle), passes then to the lower chamber of the right side (right ventricle), and from this chamber is forced into the lungs to be oxidized. The openings between the chambers of each side and into the aorta are guarded by valves.