What is created when the foramen ovale closes?

When the foramen ovale closes, it results in the formation of a fossa ovalis. This is a small depression in the interatrial septum of the heart, which is the wall that separates the left and right atria.

During fetal development, the foramen ovale serves as an important pathway, allowing blood to bypass the non-functioning fetal lungs and flow directly from the right atrium to the left atrium. After birth, when the baby's lungs become functional and the pressure in the left atrium increases, the foramen ovale typically closes. Over time, the tissue of the heart where this opening was located becomes scar tissue, leading to the development of the fossa ovalis.

The presence of this depression indicates that the opening has successfully closed, and it typically does not have any functional significance in adults. Understanding this anatomical change is essential for grasping how the circulatory system transitions from fetal to postnatal life.