Which structure acts as an internal ridge in the right atrium?

The cristae terminalis serves as an internal ridge within the right atrium, playing a significant role in the anatomy and function of this chamber. This muscular ridge separates the smooth-walled part of the right atrium, which is derived from the embryonic sinus venosus, from the trabeculated portion that contains pectinate muscles. The cristae terminalis helps in directing blood flow within the atrium by acting as a boundary between the different anatomical regions, thus enabling efficient atrial contraction and aiding in the overall function of the heart.

In contrast, the chordae tendinae are fibrous cords that connect the papillary muscles to the atrioventricular valves, primarily contributing to the function of the valves rather than functioning as a structural component within the atrial interior. The interatrial septum is a wall that separates the right and left atria but does not serve as an internal ridge specific to the right atrium. The coronary sinus, which collects blood from the heart muscle itself, is located in the atrioventricular septum but is not an internal ridge within the right atrium. Therefore, the cristae terminalis is clearly identified as the correct structure acting as an internal ridge in the right