ANATOMY

Detailed explanation-1: -The shunt that bypasses the lungs is called the foramen ovale. This shunt moves blood from the right atrium of the heart to the left atrium.

Detailed explanation-2: -The interatrial septum is located between the right and left atria. In the fully formed heart, the interatrial septum has a central depression called the oval fossa (i.e., fossa ovalis), which is a remnant of the foramen ovale, a structure that connected the atria during fetal development.

Detailed explanation-3: -The hole between the top two heart chambers (right and left atrium) is called a patent foramen ovale (PFO). This hole allows the oxygen rich blood to go from the right atrium to left atrium and then to the left ventricle and out the aorta.

Detailed explanation-4: -The fossa ovalis is a depressed structure, of varying shapes, located in the inferior aspect of the right interatrial septum. [1] A remnant of an interatrial opening, the foramen ovale, which has a significant role in fetal circulation, the fossa ovalis forms by the fusion of the septum primum and septum secundum.