Crista terminalis

The teminal crest of the heart (Crista terminalis) is a prominent, C-shaped fibromuscular ridge located on the posterolateral wall of the right atrium. It serves as the internal counterpart to the external sulcus terminalis, demarcating the boundary between the smooth-walled venous inflow portion of the right atrium (derived from the sinus venosus) and the rough-walled right atrial appendage, which contains pectinate muscles.

The crista terminalis extends from the superior vena cava orifice superiorly to the inferior vena cava orifice inferiorly, and is an important anatomical landmark for localizing the sinus node, which is situated near its superior aspect at the SVC-atrial junction.

The structure varies in thickness and prominence among individuals, and pectinate muscles radiate from it into the right atrial appendage. The crista terminalis is clinically significant as it can be mistaken for a right atrial mass on imaging, and it is a common site of origin for focal right atrial tachycardias and other atrial arrhythmias due to its anisotropic conduction properties