The two coronary arteries together supply the entire myocardium. Their territories are best understood by surface and septal distribution.
Right Coronary Artery — Area of Distribution
Region
Structures Supplied
Right atrium
Entire right atrium, including the SA node region
Right ventricle
Greater part of the right ventricle (except the narrow strip adjoining the anterior interventricular groove)
Left ventricle
Small part of the left ventricle adjoining the posterior interventricular groove
Interventricular septum
Posterior one-third of the interventricular septum (via posterior interventricular artery)
Conducting system
SA node (60%), AV node (almost always), AV bundle, right branch of AV bundle, most of left branch of AV bundle
Left Coronary Artery — Area of Distribution
Region
Structures Supplied
Left atrium
Entire left atrium
Left ventricle
Greater part of the left ventricle (except the strip adjoining the posterior interventricular groove)
Right ventricle
Small part of the right ventricle adjoining the anterior interventricular groove
Interventricular septum
Anterior two-thirds of the interventricular septum (via anterior interventricular artery / LAD)
Conducting system
SA node (40%), part of the left branch of the AV bundle
Summary Diagram
Anterior interventricular groove
↑
[LCA territory] [RCA territory]
Left ventricle (most) Right ventricle (most)
Ant. 2/3 septum Post. 1/3 septum
Left atrium Right atrium
↓
Posterior interventricular groove
Key Points
The anterior interventricular artery (LAD) is the single most important branch — it supplies the anterior wall of both ventricles and the anterosuperior septum, including the bundle branches.
The posterior interventricular artery (from the dominant artery) supplies the postero-inferior septum and the AV node.
On cross-section, a line through both interventricular grooves roughly divides the two coronary territories: the left/anterior two-thirds belongs to the LCA and the right/posterior one-third to the RCA.
The coronary arteries are the sole arterial supply to the heart. Functionally they behave as end-arteries despite anatomical anastomoses.
