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Structure

Right atrium

Content last updated · 2 min read ·

This is the date the draft was written, not a medical review date.

The right atrium receives deoxygenated blood from the superior and inferior venae cavae and the coronary sinus and passes it through the tricuspid valve to the right ventricle. It also houses the sinoatrial node.

Terminologia Anatomica (Latin): Atrium dextrum · Open in the 3D atlas

Location

Forms the right border of the heart, behind the right side of the sternum. The right auricle overlaps the root of the aorta anteriorly.

Structure

A smooth-walled sinus venarum (where the venae cavae enter) is separated by the crista terminalis from the rough pectinate muscles of the atrium proper and auricle. The septum bears the fossa ovalis; the coronary sinus opens near the septal tricuspid leaflet, within the triangle of Koch that contains the AV node.

Blood supply

Supplied mainly by atrial branches of the right coronary artery, including the sinoatrial nodal artery in most people (about 55 to 70% in published series; the left circumflex supplies it in most of the rest).

Innervation

Autonomic fibres from the cardiac plexus (vagal and sympathetic), densest around the sinoatrial and AV nodes.

Function

Acts as a reservoir and conduit for systemic venous return, with an active contraction that adds the final fraction of ventricular filling. Its stretch receptors and natriuretic peptide secretion take part in volume regulation.

Clinical correlations

The fossa ovalis marks the closed foramen ovale; a patent foramen ovale persists in roughly a quarter of adults and secundum atrial septal defect arises here. Atrial flutter often uses the cavotricuspid isthmus, a common catheter ablation target. Central venous catheter tips are placed near the cavoatrial junction.

Common exam points

  • Crista terminalis separates the smooth sinus venarum from the pectinate part; the SA node lies at its upper end near the SVC opening.
  • Fossa ovalis is the remnant of the foramen ovale; the limbus is its raised rim.
  • Triangle of Koch: tendon of Todaro, septal tricuspid leaflet and coronary sinus ostium; the AV node lies within it.
  • Venous openings: SVC (no valve), IVC (Eustachian valve), coronary sinus (Thebesian valve).

References

  1. Drake RL, Vogl AW, Mitchell AWM. Gray's Anatomy for Students. Elsevier — Tier 3 (textbook)
  2. Moore KL, Dalley AF, Agur AMR. Clinically Oriented Anatomy. Wolters Kluwer, 8th edition (2018) — Tier 3 (textbook)
  3. Federative Committee on Anatomical Terminology (FCAT). Terminologia Anatomica: International Anatomical Terminology. Thieme (1998) — Tier 1 (standards / international bodies)

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