Where is the foramen ovale located?

• A. On the septal wall of the right atrium
• B. On the septal wall of the left atrium
• C. On the floor of the right ventricle
• D. On the lateral wall of the left ventricle

Answer: (A)

The foramen ovale is an opening in the interatrial septum that allows blood to pass from the right atrium to the left atrium in fetal life, bypassing the nonfunctional lungs. It is located in the septal wall of the right atrium. After birth, the increase in left atrial pressure and the decrease in right atrial pressure typically close this opening, forming the fossa ovalis. If it remains open (patent foramen ovale), it can persist into adulthood.