Terminal sulcus (heart)

The separation of the right atrial pectinate muscle from the sinus venarum is indicated externally by a groove, the terminal sulcus (sulcus terminalis), which extends from the front of the superior vena cava to the front of the inferior vena cava, and represents the line of union of the sinus venosus of the embryo with the primitive atrium. On the internal aspect of the right atrium, corresponding to the sulcus terminalis is the crista terminalis.

The superior border the sulcus terminalis designates the transverse plane in which the SA node resides. The inferior border designates the transverse plane in which the AV node resides.