Septum primum

Septum primum
Interior of dorsal half of heart from a human embryo of about thirty days. (Septum primum labeled at center top.)
Details
Latin	Septum primum
Carnegie stage	13
Days	29
Gives rise to	atrial septum
Identifiers
TA
TH	{{#property:P1694}}
TE	{{#property:P1693}}
FMA	{{#property:P1402}}
Anatomical terminology [[[d:|edit on Wikidata]]]

During heart development of a human embryo, 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 (i.e. "the first opening"). 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 (i.e. "the second opening"). The septum primum will eventually form part of the fossa ovalis. Blood flow between atria will continue through the foramen ovale (heart).

References

This article incorporates text in the public domain from the 20th edition of Gray's Anatomy (1918)

External links

• Overview at um.edu.mt
• Diagram at lww.com
• MedEd at Loyola GrossAnatomy/thorax0/Heart_Development/Atria.html - "Atrial Partitioning"