The coronary arteries derive their name from the crown-like configuration of the vessels around the anatomic base of the heart. They are usually two in number (see variations) and arise from the right and left coronary sinuses of Valsalva. The coronary sinuses are dilatations of the aortic root above the three leaflets of the aortic valve. The posterior sinus usually does not give rise to a coronary vessel.
The right coronary artery lies embedded in fat in the right coronary sulcus between the right atrium and right ventricle. Near its origin it usually gives rise to a small branch to the sinoatrial node. It gives off a sizable marginal branch which supplies the anterior and diaphragmatic surfaces of the right ventricle. It usually then turns into the posterior interventricular sulcus as the posterior interventricular artery. As it turns into the posterior interventricular sulcus it sends a branch to the atrioventricular (AV) node located adjacent to the tricusped valve. The posterior interventricular descends about two thirds of the way to the apex of the heart and supplies branches to the posterior third of the interventricular septum as well as the adjacent ventricular walls.
The left coronary artery passes beneath the pulmonary trunk and emerges beneath the left auricular appendage. There it splits into the left circumflex and anterior interventricular arteries. The circumflex lies in the left coronary sulcus between the left atrium and left ventricle. The anterior interventricular branch lies in the anterior interventricular sulcus and turns onto the diaphragmatic surface of the heart slightly to the right of the apex. The anterior interventricular (also called anterior descending) artery supplies penetrating branches to the anterior two thirds of the interventricular septum and the contained conducting fibers as well as the adjacent ventricular walls. The circumflex continues around toward the junction of the coronary and posterior interventricular sulcus but does not usually anastomose with the right coronary system.
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