Coronary sinus
Sinus coronarius
CardiovascularOrgansThorax
- What it is
- A wide venous channel lying in the posterior atrioventricular groove between the left atrium and left ventricle, opening into the right atrium between the IVC opening and the tricuspid valve. Shown with its tributary the middle cardiac vein in the posterior interventricular groove.
- Function
- Collects most of the venous blood of the heart wall (great, middle and small cardiac veins) and returns it to the right atrium.
- Size
- About 3–5 cm long and ~1 cm wide at its opening.
- Clinical note
- Its opening is guarded by the thin Thebesian valve; the heart muscle extracts ~70% of the oxygen delivered, so coronary-sinus blood is the most deoxygenated in the body.