Which wall separates the two superior chambers of the heart?

The interatrial septum is the wall that separates the two upper chambers of the heart, known as the atria—specifically, the right atrium and the left atrium. This thin muscular structure plays a crucial role in preventing the mixing of oxygen-rich blood from the left atrium and oxygen-poor blood from the right atrium, ensuring efficient circulation and oxygenation of the body.

The interatrial septum also includes an important feature called the foramen ovale, which is present in the fetal heart and allows blood to bypass the non-functioning fetal lungs. After birth, this foramen typically closes, forming the fossa ovalis.

Understanding the structure and function of the interatrial septum helps in recognizing its significance in both normal cardiac anatomy and potential congenital heart defects where this wall may be involved, such as atrial septal defects.