Heart
Cardiac dissection
Coronary vessels

Author: R. Amita, M.D.(see Authors page)

Revised: 9 December 2015, last major update December 2015

Copyright: (c) 2015, PathologyOutlines.com, Inc.

PubMed Search: Coronary vessels [title] dissection
Cite this page: Coronary vessels. PathologyOutlines.com website. http://pathologyoutlines.com/topic/heartcoronary.html. Accessed July 27th, 2017.
Gross description
  • As the left and right coronary arteries run on the surface of the heart, they can be called epicardial coronary arteries
  • The coronary arteries that run deep within the myocardium are referred to as subendocardial
  • The coronary arteries are classified as "end circulation", since it is the only source of blood supply to the myocardium
  • Two coronary arteries originate from the left side of the heart at the aortic root; the left posterior aortic sinus and 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 vessel

  • Left coronary artery:
    • The left coronary artery distributes blood to the left side of the heart, the left atrium and ventricle, and the interventricular septum
    • The circumflex artery arises from the left coronary artery and fuses with the small branches of the right coronary artery
    • The larger anterior interventricular artery, also known as the left anterior descending artery (LAD), is the second major branch arising from the left coronary artery
      • It follows the anterior interventricular sulcus around the pulmonary trunk
      • Along the way it gives rise to numerous smaller branches that interconnect with the branches of the posterior interventricular artery, forming anastomoses

  • Right coronary artery:
    • The right coronary artery distributes blood to the right atrium, portions of both ventricles, and the heart conduction system
    • Normally, one or more marginal arteries arise from the right coronary artery inferior to the right atrium
    • The marginal arteries supply blood to the superficial portions of the right ventricle
    • On the posterior surface of the heart, the right coronary artery gives rise to the posterior interventricular artery, also known as the posterior descending artery
    • It runs along the posterior portion of the interventricular sulcus toward the apex of the heart, giving rise to branches that supply the interventricular septum and portions of both ventricles

  • Coronary artery dominance:
    • The artery that supplies the posterior descending artery or AV nodal artery determines the coronary dominance
    • If the posterior descending artery is supplied by the right coronary artery (RCA), then the coronary circulation can be classified as "right-dominant"
    • If the posterior descending artery is supplied by the circumflex artery (CX), a branch of the left artery, then the coronary circulation can be classified as "left-dominant"
    • If the posterior descending artery is supplied by both the right coronary artery and the circumflex artery, then the coronary circulation can be classified as "co-dominant"
    • Approximately 70% of the general population are right-dominant, 20% are co-dominant, and 10% are left-dominant
Diagrams / tables
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Anterior circulation

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Posterior circulation

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Coronary arteries

Microscopic (histologic) description
  • Blood vessels basically contain three layers, whose thickness varies greatly depending upon the size and type of vessel (from outer to inner):
    • Tunica adventitia: outermost collagen and elastin rich layer; also has small 'vasa vasorum' as the large arteries need their own blood supply
    • Tunica media is broad and elastic with concentric fenestrated sheets of elastin, and collagen and only relatively few smooth muscle fibers
    • Tunica intima is made up of an epithelium, which is a single layer of flattened epithelial cells, together with a supporting layer of elastin rich collagen; this layer also has fibroblasts and 'myointimal cells' that accumulate lipid with aging

  • Arteries are classified into three types according to their size:
    • Large or elastic arteries
    • Medium (or muscular or distributive) arteries
    • Small arteries or arterioles, which are less than 0.5 mm in diameter

  • Venules:
    • Have a clear tunica intima layer, without any elastic fibers, and a tunica media with one or two layers of muscle fibers
    • The tunica adventitia fuses with surrounding tissue

  • Vein:
    • Has a wall similar to arteries but with a thinner tunica media
    • Typically wall is much thinner than diameter of the lumen
    • With such relatively thin walls, veins tend to appear flattened or collapsed in cross section in postmortem histological preparations (in contrast to arteries, which tend to appear more round)
Microscopic (histologic) images
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Venule

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Various images

Electron microscopy images
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Small arteriole

Additional references