Sandbox: Ifeoma

Embryology

• At week 4 of pregnancy, the septum primum and septum secundum forms to divide the primordial single atrium into right and left.
• The crescent-shaped septum primum grows from primordial atrial roof towards the endocardial cushion. This partially divides the common atrium into left and right halves.
• The formation of the endocardial cushions occurs on the ventral and dorsal walls of the atrioventricular canal. The fusion divides the atrioventricular canal into right and left sides. This leads to the formation of the foramen primum which permits the flow of oxygenated blood from the right atrium to left atrium.