Library · Anatomy
Heart atrium
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The heart has two atria, a right one and a left one. Blood returning to the heart reaches the right atrium through two large veins, the superior vena cava and the inferior vena cava.
Inside the right atrium, in its upper wall, sits the sinoatrial node, a cluster of cells that generates the electrical impulse for every heartbeat. The switch for every heartbeat lives inside the right atrium. That is the source of the signal that makes both atria contract before the ventricles, the lower chambers.
Between the two atria there is a wall, the interatrial septum, and it bears a mark: the fossa ovalis. It is what is left of the foramen ovale, an opening that let blood pass from the right atrium to the left before birth.
In brief
The heart has two atria; blood returning to the heart reaches the right atrium through the superior and inferior venae cavae.
The sinoatrial node sits in the upper wall of the right atrium, and from it comes the impulse that contracts the atria before the ventricles.
The switch for every heartbeat lives inside the right atrium.
The interatrial septum separates the two atria and bears the fossa ovalis, the remnant of the foramen ovale that in fetal life let blood pass from the right atrium to the left.
Sources (4)
- National Center for Biotechnology Information, StatPearls PublishingAnatomy, Thorax, StatPearlsPublished
- National Center for Biotechnology Information, StatPearls PublishingPhysiology, Sinoatrial Node, StatPearlsPublished
- National Center for Biotechnology Information, StatPearls PublishingPhysiology, Cardiac Cycle, StatPearlsPublished
- National Center for Biotechnology Information, StatPearls PublishingAnatomy, Thorax, Heart Fossa Ovalis, StatPearlsPublished
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