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INTERATRIAL SEPTUM

Interatrial septum
Interior of right side of heart. (labeled at right, as 'atrial septum')
Interior of dorsal half of heart of human embryo of about thirty-five days.
Gray's subject #138 530
MeSH A07.541.459

The interatrial septum is the wall of tissue that separates the right and left atria of the heart.

Contents

Development

The interatrial septum forms during the first and second months of fetal development. This occurs in several stages.

The first stage is the formation of the septum primum.

The septum primum walls off a crescent-shaped portion of the hole between the right and left atria.

The part that remains open is called the foramen primum (also called the ostium primum).

The remaining part of the opening between the right and left atria is closed by the septum secundum. These two tissue layers overlap like a flap and allow blood flow to continue during fetal life.

However, with the changes in circulation that occur at birth, this flap will close permanently.

Disorders

  • Atrial septal defect is a relatively common heart malformation that occurs when the interatrial septum fails to develop properly.

References

  • Gray's Anatomy: The Anatomical Basis of Clinical Practice, 39th ed. (2005). ISBN 0-443-07168-3
  • "Septum, interatrial." Stedman's Medical Dictionary, 27th ed. (2000). ISBN 0-683-40007-X

External links

Cardiovascular system - Heart - edit
atria (interatrial septum) | ventricles (interventricular septum) | valves (chordae tendinaepapillary muscle)

right heart(vena cavaecoronary sinus) → right atrium (fossa ovalis) → tricuspid valve → right ventricle → pulmonic valve 
(pulmonary artery and pulmonary circulation)

left heart: (pulmonary veins)left atriummitral valveleft ventricleaortic valve
(aortaaortic sinus and systemic circulation)

pericardium | epicardium | endocardium | myocardium

conduction systemcardiac pacemaker | Purkinje fibers | bundle of His | SA node | AV node