Which chamber houses the crista terminalis?

Which chamber houses the crista terminalis?

• A. Right atrium
• B. Left atrium
• C. Right ventricle
• D. Left ventricle

Answer: (A)

The crista terminalis is a prominent fibromuscular ridge inside the right atrium that marks the boundary between the smooth-walled posterior wall (sinus venarum) and the rough, pectinate-muscle–lined anterior wall. It extends from the entrance of the superior vena cava down toward the inferior vena cava, serving as a natural divider within the right atrium. Because this structure resides specifically in the right atrium, that chamber houses the crista terminalis. The left atrium and the ventricles do not contain this ridge (they have their own smooth or trabeculated walls, but not this boundary).

The crista terminalis is a prominent fibromuscular ridge inside the right atrium that marks the boundary between the smooth-walled posterior wall (sinus venarum) and the rough, pectinate-muscle–lined anterior wall. It extends from the entrance of the superior vena cava down toward the inferior vena cava, serving as a natural divider within the right atrium. Because this structure resides specifically in the right atrium, that chamber houses the crista terminalis. The left atrium and the ventricles do not contain this ridge (they have their own smooth or trabeculated walls, but not this boundary).