QS Study

Interior of Right Atrium –

It is the right upper chamber of the heart. It is one of the four hollow chambers of the interior of the heart. It is located in the upper right corner of the heart superior to the right ventricle. The main function is receiving chambers for blood entering the heart.

Shape: Quadrilateral.

Contribution to the heart

  1. A sternocostal surface of the heart.
  2. The right border of the heart.
  3. The right portion of the base of the heart.


The right atrium receives venous blood from the whole body through superior & inferior venae cavae and through the coronary sinus and pumps it to the right ventricle.


Above: superior vena cava at the level of right 3rd costal cartilage.

Bellow: Inferior vena cava at the level of right 6th costal cartilage.’

Fig: Interior of Right Atrium

Internal features

It has three parts –

1) Smooth posterior surface.

2) Rough anterior surface.

3) Septal wall.

(1) Smooth posterior surface (sinus venarum): Most of the tributaries open into it:

  • Superior vena cava.
  • Inferior vena cava.
  • Coronary sinus.
  • Venae Cordis minimae.
  • Sometimes right marginal vein.

(2) Rough anterior part (pectinate part):

  1. Musculi pectinate: A series of transverse muscular ridges directing downwards and forwards arises from crista tenninalis giving the appearance of the teeth of a comb.
  2. In the auricle, the muscle fibers are arranged in a reticular manner.

(3) Septal wall:

(a) Fossa ovalis: An oval depression in lower pan of the septum. It represents the embryonic septum primunt,

(b) Limbus fossa ovalis: This is the prominent edge of the fossa ovalis. It represents the embryonic septum secundum.

(c) Sometimes a foramen ovate presents above the fossa ovalis in some individuals.


Smooth part: From absorbed right horn of sinus venosus.

Rough part: From primitive atrium (right part).

Developmental anomalies are –

  1. Defects of osteum secundum.
  2. Persistence of osteum primum.
  3. Defects dorsal to the fossa ovalis.
  4. Persistence of common atrioventricular orifice.
  5. Defects in the adjacent septa.
  6. Drainage of pulmonary veins into the right atrium.
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