Which structure is the remnant of the fetal foramen ovale on the interatrial septum?

Which structure is the remnant of the fetal foramen ovale on the interatrial septum?

• A. Left Pulmonary Artery
• B. Left Common Carotid Artery
• C. Fossa Ovalis
• D. Aortic Semilunar Valve

Answer: (C)

The structure that marks the remnant of the fetal foramen ovale on the interatrial septum is the fossa ovalis. In fetal life, the foramen ovale lets blood flow from the right atrium to the left atrium, bypassing the nonfunctioning fetal lungs. After birth, the pressure change with lung expansion pushes the septa together and the hole functionally closes; over time the tissue fuses to form a fibrous depression called the fossa ovalis in the interatrial septum. Its location is the smooth, shallow oval impression on the septum that you can feel as the fossa ovalis, with a surrounding rim known as the limbus. The other structures listed are not located on the interatrial septum or related to the foramen ovale remnant: the left pulmonary artery is part of the pulmonary circulation, the left common carotid artery branches from the aortic arch, and the aortic semilunar valve sits between the left ventricle and the aorta.

The structure that marks the remnant of the fetal foramen ovale on the interatrial septum is the fossa ovalis. In fetal life, the foramen ovale lets blood flow from the right atrium to the left atrium, bypassing the nonfunctioning fetal lungs. After birth, the pressure change with lung expansion pushes the septa together and the hole functionally closes; over time the tissue fuses to form a fibrous depression called the fossa ovalis in the interatrial septum. Its location is the smooth, shallow oval impression on the septum that you can feel as the fossa ovalis, with a surrounding rim known as the limbus. The other structures listed are not located on the interatrial septum or related to the foramen ovale remnant: the left pulmonary artery is part of the pulmonary circulation, the left common carotid artery branches from the aortic arch, and the aortic semilunar valve sits between the left ventricle and the aorta.