Clinical Anatomy of Thorax 2 – Coronary Arteries & Great Vessels
1. Arteries: right & left coronary arteries; branches & variation of
patterns, distribution (esp LAD); ascending aorta, arch of aorta,
descending thoracic aorta; pulmonary trunk, pulmonary arte ries.
2. Veins: coronary sinus, tributaries, anterior cardiac veins, venae cordis
minimae, SVC; IVC; pulmonary veins.
A = anterior view
B = posterior view
The first branches from the ascending aorta are the right and left coronary arteries, they branch off
just beyond the aortic semilunar valves.
Artery/Branch
Origin
Course
Distribution
Anastomoses
Right Coronary
Right aortic
sinus
Follows
coronary (AV)
groove between
the atria and
ventricles
Right atrium, SA
and AV nodes,
posterior part of
IV septum
Circumflex and
anterior IV
branches of left
coronary artery
SA Nodal
Right coronary
artery near its
origin
Ascends to SA
node
Pulmonary trunk
and SA node
Right marginal
Right coronary
artery
Passes to
inferior margin
of heart and
apex
Right ventricle
and apex of
heart
Posterior IV
Right coronary
artery
Runs from
posterior IV
groove to apex
of heart
Right and left
Circumflex and
ventricles and IV anterior IV
septum
branches of left
coronary artery
AV nodal
Right coronary
artery near
Passes to AV
AV node
IV branches
origin of
posterior IV
artery
node
Left Coronary
Left aortic sinus
Runs in AV
groove and
gives off anterior
interventricular
and circumflex
branches
Most of left
atrium and
ventricle, IV
septum and AV
bundles; may
supply AV node
SA nodal
Circumflex
branch
Ascends on
posterior
surface of left
atrium to SA
node
Left atrium and
SA node
Anterior
interventricular
(LAD, left
anterior
descending)
Left coronary
artery
Passes along
anterior IV
groove to apex
of heart
Right and left
ventricular and
IV septum
Posterior IV
branch of right
coronary artery
Circumflex
Left coronary
artery
Passes to left in
AV groove and
runs to posterior
surface of heart
Left atrium and
left ventricle
Right coronary
artery
Left marginal
Circumflex
branch
Follows left
border of heart
Left ventricle
IV branches
Right coronary
artery
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Variations of pattern of coronary arteries
Most people (80%) are RCA dominant, 10% are LCA dominant and 10% have codominance.
Some people have only a single coronary artery (rare), in some people, the circumflex
branch arises from the right aortic sinus and rarely some people have an accessory coronary
artery.
Aorta
The ascending aorta (approx 2.5cm in diameter) begins at the aortic orifice. The aortic valve,
obliquely placed is located posterior to the left side of the sternum at the level of the 3rd
intercostals space.
The arch of the aorta begins posterior to the 2nd right sternocostal joint at the level of the
sterna angle, it arches superoposteriorly and to the left. It ascends anterior to the right
pulmonary artery and the bifurcation of the trachea and reaches its apex at the left side of
the trachea and oesophagus as it passes over the root of the left lung. The arch descends
on the left side of the body of T4 veterbra.
The arch becomes the thoracic aorta posterior to the 2nd left sternocostal joint.
Pulmonary Trunk
This is approximately 5cm long and 3cm wide, it’s the arterial continuation of the right
ventricle and divides into left and right pulmonary arteries. The pulmonary arteries take
deoxygenated blood to the lungs for oxygenation.
Venous drainage of the heart
The coronary sinus is the main vein of the heart. It is wide and runs from left to right in the
posterior part of the coronary groove.
The coronary sinus receives the anterior interventricular vein (great cardiac vein) at its left
end, the posterior interventricular or middle cardiac vein and small cardiac veins to its right.
The left posterior ventricular vein and left marginal vein also open into the coronary sinus.
The great cardiac vein (anterior interventricular) is the main tributary of the coronary sinus, it
begins near the apex of the heart and ascends with the LAD of the LCA. It drains the areas
of the heart supplied by the left coronary artery. The middle and small cardiac veins drain
most of the areas supplied by the RCA.
Several smaller anterior cardiac veins begin over the anterior surface of the right ventricle,
cross over the coronary groove and usually end directly in the right atrium, sometimes
entering the small cardiac vein.
The venae cordis minimae (smallest cardiac veins) are minute vessels that begin in the
capillary beds of the myocardium and open directly into the chambers of the heart, chiefly
the atria. They are valveless communications with the capillary beds of the myocardium and
may carry blood from the heart chambers to the myocardium. They may also provide
collateral circulation for parts of the heart musculature.
The SVC and IVC enters the heart through the oblique pericardial sinus.
The pulmonary veins return oxygenated blood to the left atrium.