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Coronary Circulation Anatomy
Coronary Circulation Anatomy
The heart is an exceptionally active pump composed primarily of cardiac muscle cells (cardiomyocytes) that must function continuously throughout life. Like all living cells, cardiomyocytes require a constant supply of oxygen and nutrients and an efficient means of waste removal. To meet these demands, the heart possesses its own specialized and highly developed blood supply known as the coronary circulation.
Because the heart’s workload is constant and intense, its metabolic requirements are greater than those of most other tissues. As a result, the coronary circulation is extensive and finely regulated.
However, unlike blood flow to many other organs, coronary blood flow is not continuous.
Instead, it is closely linked to the cardiac cycle. Coronary circulation reaches its peak during ventricular relaxation (diastole), when the heart muscle is not contracting and the coronary vessels are open. During ventricular contraction (systole), the powerful contraction of the myocardium compresses the coronary vessels, significantly reducing blood flow to the heart muscle.
This cyclical pattern ensures that the heart receives adequate oxygen and nutrients despite its constant activity, and it highlights the critical dependence of cardiac function on efficient coronary perfusion.
“Coronary Circulation” by OpenStax College, from Anatomy & Physiology, Connexions Web site (http://cnx.org/content/col11496/1.6/, June 19, 2013), licensed under CC BY 3.0 (https://creativecommons.org/licenses/by/3.0/).
Changes made: Labels deleted and replaced, image cropped.
Coronary Arteries
Coronary Arteries
The coronary arteries supply oxygenated blood to the myocardium and other tissues of the heart. These vessels originate from the ascending aorta, immediately after it emerges from the left ventricle.
Just superior to the aortic semilunar valve are three small dilations in the aortic wall known as aortic sinuses. Two of these (the left posterior aortic sinus and the anterior aortic sinus) give rise to the left and right coronary arteries, respectively. The third sinus, the right posterior aortic sinus, typically does not give rise to a coronary vessel.
Coronary arteries that remain on the surface of the heart and travel within the sulci are referred to as epicardial coronary arteries.
The left coronary artery (LCA) supplies blood to the left side of the heart, including:
the left atrium
the left ventricle
much of the interventricular septum.
One major branch of the LCA is the circumflex artery, which travels within the coronary sulcus toward the left side of the heart. It eventually anastomoses with small branches of the right coronary artery.
The second major branch is the anterior interventricular artery, commonly known as the left anterior descending (LAD) artery. This vessel follows the anterior interventricular sulcus toward the apex of the heart and supplies much of the anterior ventricular walls and septum. Along its course, it gives rise to numerous smaller branches that interconnect with branches of the posterior interventricular artery, forming anastomoses.
“Coronary Circulation” by OpenStax College, from Anatomy & Physiology, Connexions Web site (http://cnx.org/content/col11496/1.6/, June 19, 2013), licensed under CC BY 3.0 (https://creativecommons.org/licenses/by/3.0/).
Changes made: Labels deleted and replaced, image cropped.
An anastomosis is a junction where blood vessels interconnect, providing alternate routes for blood flow if one vessel becomes partially obstructed. In the heart, however, these anastomoses are relatively small and often insufficient to fully compensate for a blocked coronary artery. As a result, obstruction of a coronary artery frequently leads to myocardial infarction, or death of cardiac muscle tissue supplied by that vessel.
The right coronary artery (RCA) travels along the coronary sulcus and supplies blood to:
the right atrium
portions of both ventricles
much of the cardiac conduction system
Inferior to the right atrium, one or more marginal arteries typically branch from the RCA and supply the superficial regions of the right ventricle. On the posterior surface of the heart, the RCA gives rise to the posterior interventricular artery, also known as the posterior descending artery (PDA). This artery runs along the posterior interventricular sulcus toward the apex of the heart and supplies branches to the interventricular septum and adjacent regions of both ventricles.
Coronary Veins
Coronary Veins
The coronary veins are responsible for draining deoxygenated blood from the myocardium and generally run parallel to the major coronary arteries on the surface of the heart. These veins collect blood from the heart muscle and return it to the right atrium.
The largest of these vessels is the great cardiac vein, which is initially visible on the anterior surface of the heart as it follows the anterior interventricular sulcus. It runs alongside the anterior interventricular artery and drains the regions supplied by that artery. As it continues, the great cardiac vein curves into the coronary sulcus and empties into the coronary sinus on the posterior surface of the heart.
Along its course, the great cardiac vein receives several major tributaries. These include:
the posterior cardiac vein, which parallels the marginal branch of the circumflex artery and drains the regions supplied by that vessel
the middle cardiac vein, which follows the posterior interventricular sulcus and drains areas supplied by the posterior interventricular artery.
The small cardiac vein runs alongside the right coronary artery and drains blood from the posterior surfaces of the right atrium and right ventricle.
The coronary sinus is a large, thin-walled venous structure located on the posterior surface of the heart within the atrioventricular (coronary) sulcus. It serves as the main venous collection point for the heart and empties directly into the right atrium.
In addition to these vessels, the anterior cardiac veins drain the anterior surface of the right ventricle. These veins typically parallel small cardiac arteries. Unlike most coronary veins, the anterior cardiac veins do not drain into the coronary sinus; instead, they empty directly into the right atrium.
Need a recap? Take a look at the Coronary Circulation anatomy notes here.
Need a recap? Take a look at the Coronary Circulation anatomy notes here.
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References
References
Gray, H. (1918). Anatomy of the human body (W. H. Lewis, Ed.; 20th ed.). Lea & Febiger.
J Gordon Betts, Desaix, P., Johnson, E., Johnson, J. E., Korol, O., Kruse, D., Poe, B., Wise, J., Womble, M. D., & Young, K. A. (2013). Anatomy & physiology. Openstax College, Rice University. https://openstax.org/details/books/anatomy-and-physiology
Based on OpenStax, Anatomy and Physiology (2013), licensed under CC BY 4.0.
Access for free at https://openstax.org/books/anatomy-and-physiology/pages/1-introduction.
Content paraphrased; adaptations were made.
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