General Composition of Blood
Introduction to the Cardiac Arteries:
The heart receives nutrients and gases from it’s own set of arteries, veins, and capillaries. Blood enters the coronary circulatory system through the left coronary artery and the right coronary artery, which exit the aorta just above the cusps of the semilunar valves.
Anterior Cardiac Arteries:
- After running a short distance between the pulmonary trunk artery and the left auricle, the left coronary artery (= LCA; left main coronary artery) emerges onto the anterior surface of the heart.
- Near this point, it branches into the anterior interventricular artery (= left anterior descending artery or branch; LAD) and the left circumflex artery (= LCX; branch of the left coronary artery).
- The anterior interventricular artery lies in the anterior interventricular sulcus and gives off branches that supply blood to the anterior ventricles and anterior interventricular septum.
- The left circumflex artery runs along the coronary sulcus (= between the left atrium and ventricle) to the posterior side of the heart, where it usually ends in an anastomosis with the right coronary artery.
- One or more left marginal arteries (= obtuse marginal arteries (OM) or left marginal branches) typically branch from the left circumflex artery as it travels around the heart.
- The left circumflex artery and its branches supply blood to the left atrium and posterior portions of the left ventricle.
- The right coronary artery travels along the coronary sulcus (between the right atrium and ventricle), where it typically gives off smaller branches to the right atrium, AV node (80% of people), and SA node (55% – 60% of people).
- Larger right marginal arteries (= right marginal branches) also diverge from the right coronary artery as it continues around the heart.
- The right marginal arteries supply blood to the lateral wall of the right ventricle.
Posterior Cardiac Arteries:
- On the posterior side of the heart, the right coronary artery typically (80% – 85% of people) gives rise to the posterior interventricular artery (PIV) or posterior descending artery (PDA), which runs along the posterior interventricular sulcus and supplies blood to both ventricles and the posterior interventricular septum.