Which structures are in the immediate vicinity of the interatrial septum?

Which structures are in the immediate vicinity of the interatrial septum?

• A. LA, aorta, pericardium, CS os
• B. RA, SVC, LV, pulmonary veins
• C. RA, LA, right coronary artery, tricuspid annulus
• D. LA, RA, pulmonary artery, mitral valve

Answer: (A)

Think about what sits right next to the wall that divides the two atria. The left atrium lies directly against the interatrial septum, and the coronary sinus ostium opens into the right atrium near that same septal region, so it’s effectively at the boundary between the atria. The aorta also sits just anterior to this area as it emerges from the heart, so it’s in close proximity to the septum. The pericardium, the outer covering of the heart, surrounds this whole region as well, bringing it into near contact with the septal area. Other structures listed aren’t as closely related to the septum itself. The left ventricle and pulmonary veins are more distant from the septal wall, and while the right coronary artery or tricuspid annulus relate to the right-sided heart, they aren’t the structures you’d class as in the immediate vicinity of the interatrial septum.

Think about what sits right next to the wall that divides the two atria. The left atrium lies directly against the interatrial septum, and the coronary sinus ostium opens into the right atrium near that same septal region, so it’s effectively at the boundary between the atria. The aorta also sits just anterior to this area as it emerges from the heart, so it’s in close proximity to the septum. The pericardium, the outer covering of the heart, surrounds this whole region as well, bringing it into near contact with the septal area.

Other structures listed aren’t as closely related to the septum itself. The left ventricle and pulmonary veins are more distant from the septal wall, and while the right coronary artery or tricuspid annulus relate to the right-sided heart, they aren’t the structures you’d class as in the immediate vicinity of the interatrial septum.