Cardiac Structure - Right Atrium

Lateral view of the atrial septum. The opening of the superior vena cava (SVC) into the atrium is shown. The small arrowheads delineate the limbus of the fossa ovalis. A large eustachian valve (EV) is seen at the opening of the inferior vena cava. In this case the eustachian valve has many fenestrations. When it is heavily fenestratated it looks like a net and it is called the Chiari network. The thebesian valve is also distinct as the valve at the opening of the coronary sinus (CS). The insertion border of the septal leaflet of the tricuspid valve is seen in the caudal end of the atrial septum.

Coronal sectioning of the atrial septum can show several distinctive features such as the limbus of the fossa ovalis, the fosa, and the septum primum and secundum components of the fossa.

The structure of the tricuspid valve can be seen here.