right atrium (anatomy)

Last reviewed 01/2018

The right atrium is the first heart chamber on the right side of the heart. It is an obliquely-formed quadrangle in shape. It forms the majority of the right border of the heart. It receives blood from the:

  • superior vena cava
  • inferior vena cava
  • coronary sinus
  • venae cordis minimae
  • anterior cardiac veins
  • right marginal vein

The right atrium is slightly elongated; the superior part is marked by the orifice of the superior vena cava. The inferior end of the chamber has the tricuspid - atrioventricular - orifice.

It pumps blood into the right ventricle through the tricuspid valve. Anatomically, it can be divided into two areas with different embryological origins:

  • anterior part
  • posterior part

The two are separated by the crista terminalis.