Atrial septum primum
Atrial septum primum
Definition
In the developing heart, the cavity of the primitive atrium becomes subdivided into right and left chambers by a septum, the septum primum, which grows downward into the cavity. The increasingly smaller gap below it (before it fuses with the endocardial cushion) is known as the ostium primum. The septum primum eventually fuses with the endocardial cushion, closing the ostium primum off completely. Meanwhile, perforations appear in the superior part of the septum primum, forming the ostium secundum. This will eventually form part of the fossa ovalis.
Also known as atrial septum primum, interatrial septum primum, septum primum — per UBERON
The Atrial septum primum is a part of the Cardiovascular.