Coronary sinus

At a glance

English

Coronary sinus

Latin (TA2)

Sinus coronarius

System

Vein

Region

Trunk

Side

Single, on the midline

About the coronary sinus

The coronary sinus is the main collecting vessel for blood that has passed through the heart muscle. It lies on the back of the heart, in the part of the coronary (atrioventricular) groove between the left atrium and left ventricle, and runs from left to right to open into the right atrium. It takes its name from corona, Latin for a crown, because the channel and its tributaries partly encircle the heart. It is a few centimetres long and noticeably wider than the veins feeding it, roughly the width of a fingertip near its end, and its wall contains some cardiac muscle.

The sinus begins where the great cardiac vein is joined by the small oblique atrial vein (of Marshall). A small valve, often described in two unequal parts and named after Vieussens, commonly marks this junction, which is also slightly narrowed. Along its course the sinus receives the posterior vein of the left ventricle, the left marginal vein (often via the great cardiac vein), the middle cardiac vein from the posterior interventricular groove, and the small cardiac vein from the right side of the groove. In practice it can be thought of as the widened final stretch of the great cardiac vein.

The opening into the right atrium lies between the opening of the inferior caval vein and the tricuspid orifice, just above the septal cusp of the tricuspid valve. A thin crescent of endocardium, the Thebesian valve, partly covers it. Not all cardiac venous blood takes this route: the anterior cardiac veins open straight into the right atrium, and tiny smallest cardiac veins open into all four chambers.

The coronary sinus is a practical gateway for cardiologists. Catheters and electrodes are passed through it to record electrical activity from the left side of the heart, and leads for cardiac resynchronisation pacing are threaded into its tributaries to stimulate the left ventricle.

Course and drainage

Begins at

Begins at the left end of the posterior coronary groove where the oblique atrial vein joins the great cardiac vein.

Drains into

Opens into the right atrium between the inferior vena caval opening and the tricuspid orifice, partly covered by the Thebesian valve.

Drains

Returns most of the venous blood of the heart wall to the right atrium, through the great, middle and small cardiac veins, the posterior left ventricular vein and the oblique atrial vein.