Sulcus terminalis of heart

The sulcus terminalis of heart (terminal sulcus of the heart) is an external groove of the surface of the heart that indicates separation of the auricula from the sinus venarum. It 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.

This groove corresponds to the internal crista terminalis, a C-shaped muscular ridge that separates the smooth posterior wall of the right atrium from the anterior wall, which is characterized by pectinate muscles.

The sinoatrial (SA) node is located subepicardially within the superior part of the terminal sulcus, near the junction of the superior vena cava and the right atrium, making this groove a key anatomical landmark for electrophysiological procedures and surgical interventions.