---
title: Coronary circulation
description: How the heart's coronary arteries and veins are arranged, which parts of the heart each artery supplies, and what happens when an artery narrows.
type: anatomy
aliases:
  - coronary arteries
  - coronary blood flow
  - blood supply of the heart
  - cardiac veins
sources:
  - tier: reference
    org: statpearls
    title: Anatomy, Thorax, Heart Arteries
    year: 2023
    url: https://www.ncbi.nlm.nih.gov/books/NBK470522/
  - tier: reference
    org: statpearls
    title: Anatomy, Thorax, Heart Veins
    year: 2023
    url: https://www.ncbi.nlm.nih.gov/books/NBK549786/
  - tier: textbook
    title: Anatomy and Physiology 2e (OpenStax), chapter 19.1 Heart Anatomy
    year: 2022
    isbn: 9781711494067
    url: https://openstax.org/books/anatomy-and-physiology-2e/pages/19-1-heart-anatomy
sources_checked: 2026-10-11
review: null
---

The heart pumps blood to the whole body, but its own muscle receives blood through separate vessels: the coronary arteries.<Cite n={3} /> They arise from the very first part of the aorta, just after it leaves the left ventricle.<Cite n={3} /> Blood from the heart muscle returns through the coronary veins and mostly collects in the coronary sinus, which drains into the right atrium.<Cite n={[2, 3]} />

<Diagram name="coronary-arteries">
  <p slot="scheme">The left coronary artery divides into the anterior interventricular and circumflex arteries; the right coronary artery runs in the right part of the coronary sulcus.<Cite n={1} /> In most people the posterior interventricular artery comes from the right coronary artery (right dominance).<Cite n={1} /></p>
</Diagram>

## How it is built

<Patient>

There are two coronary arteries: the left and the right.<Cite n={1} /> They arise from the base of the aorta.<Cite n={1} />

**<Structure id="left-main-coronary-artery">The left coronary artery</Structure>** supplies the left side of the heart: the left atrium, the left ventricle and the wall between the ventricles (the septum).<Cite n={3} /> It divides into two large branches.<Cite n={1} />

- **<Structure id="left-anterior-descending-artery">The anterior interventricular artery</Structure>** (often called the left anterior descending artery, or LAD) runs along the front of the heart between the ventricles.<Cite n={3} /> Its branches supply most of the septum between the ventricles.<Cite n={1} />
- **<Structure id="circumflex-artery">The circumflex artery</Structure>** runs to the left in the groove between the atria and the ventricles and supplies the back and side of the left ventricle.<Cite n={1} />

**<Structure id="right-coronary-artery">The right coronary artery</Structure>** runs in the right-hand groove between the atrium and the ventricle.<Cite n={1} /> It supplies the right atrium, parts of both ventricles and part of the heart's conduction system.<Cite n={3} /> It gives off a branch to the sinoatrial node and, near the end of its course, a branch to the atrioventricular node, the two main nodes of the conduction system.<Cite n={1} /> There is more about them in the article on the [conduction system](../conduction-system/).

**<Structure id="cardiac-veins">The large veins of the heart</Structure>** run alongside the arteries.<Cite n={[2, 3]} /> The great cardiac vein starts at the apex and runs alongside the anterior interventricular artery.<Cite n={2} /> The veins drain into the coronary sinus, a large vein on the back of the heart that opens into the right atrium.<Cite n={[2, 3]} /> The anterior cardiac veins bypass the sinus and drain straight into the right atrium.<Cite n={[2, 3]} />

</Patient>

<Student>

The coronary arteries arise from two of the three aortic sinuses, located just superior to the aortic valve.<Cite n={3} /> The left coronary artery (left main) extends along the coronary sulcus and divides into the circumflex artery and the anterior interventricular artery (left anterior descending, LAD).<Cite n={1} /> The LAD follows the anterior interventricular sulcus.<Cite n={3} />

- **The LAD** gives off septal and diagonal branches.<Cite n={1} /> The septal branches supply the anterior two-thirds of the interventricular septum and the bundle of His; the diagonal branch supplies the anterolateral papillary muscle.<Cite n={1} />
- **The circumflex artery** follows the coronary sulcus to the left; it and its branches supply the posterolateral wall of the left ventricle.<Cite n={1} />
- **The right coronary artery (RCA)** supplies the anterior and diaphragmatic surfaces of the right atrium and right ventricle.<Cite n={1} /> Its branches are the SA nodal artery, the right marginal artery along the acute margin of the heart, and the AV nodal branch, which arises at the diaphragmatic surface.<Cite n={1} /> The posterior interventricular (posterior descending) artery gives off septal branches.<Cite n={1} /> It runs towards the apex and supplies the septum and parts of both ventricles.<Cite n={3} />

**Coronary dominance** depends on which artery the posterior descending artery arises from.<Cite n={1} /> If it arises from the RCA, the circulation is right dominant, which occurs in at least 70% of cases; if from the left coronary artery, it is left dominant, in about 10%; in codominance both arteries supply it, in 20%.<Cite n={1} />

**Venous drainage.** The coronary sinus lies in the left posterior atrioventricular groove and opens into the right atrium through its own opening, the coronary sinus orifice.<Cite n={2} /> Its tributaries are:

- the great cardiac vein, which runs from the apex alongside the anterior interventricular artery;<Cite n={2} />
- the middle cardiac vein, alongside the posterior interventricular artery;<Cite n={2} />
- the small cardiac vein, alongside the right marginal branch of the RCA.<Cite n={2} />

The anterior cardiac veins drain the anterior wall of the right ventricle and empty directly into the right atrium, bypassing the coronary sinus.<Cite n={[2, 3]} /> The smallest (Thebesian) veins drain deoxygenated blood from the myocardium of all chambers.<Cite n={2} /> The system of large cardiac veins returns about three-quarters of the myocardial venous blood, and the system of smallest veins, mainly the Thebesian veins, about one-quarter.<Cite n={2} />

</Student>

<HeartModel highlight={['right-coronary-artery', 'left-main-coronary-artery', 'left-anterior-descending-artery', 'circumflex-artery', 'coronary-sinus', 'cardiac-veins']} />

## How it works

<Patient>

Blood flows through the coronary arteries most strongly when the heart muscle is relaxed, and the flow almost stops while it contracts.<Cite n={[1, 3]} /> There is more about the phases of contraction and relaxation in the article on the [cardiac cycle](../cardiac-cycle/).

The connections between branches of different coronary arteries are very small.<Cite n={3} /> So if one artery is blocked, the others can take over its work only to a small degree, and the area of muscle it supplies often dies.<Cite n={3} />

</Patient>

<Student>

Coronary blood flow is greatest during diastole, when the myocardium is relaxed, and least during systole, when the myocardium contracts.<Cite n={1} />

The coronary arteries are regarded as end arteries: each region of myocardium has a single source of blood supply.<Cite n={1} /> Anastomoses between branches do exist (circumflex branches join small branches of the RCA, and LAD branches interconnect with branches of the posterior interventricular artery), but they are very small.<Cite n={3} /> Therefore a coronary artery blockage often results in death of the myocardium that the vessel supplies.<Cite n={3} />

</Student>

## In disease

<Patient>

Narrowing and blockage of the coronary arteries are covered in the article on [coronary heart disease](../../disease/coronary-heart-disease/). It explains why this happens, how it presents and when to call an ambulance urgently.

</Patient>

<Student>

Coronary atherosclerosis, angina and myocardial infarction are covered in the article on [coronary heart disease](../../disease/coronary-heart-disease/), and the ECG as a method in the article on the [ECG](../../diagnostic/ecg/).

</Student>

<Quiz />