Ventrolateral view, left atrium

Ventrolateral view, right atrium

The atria (left and right) are often described as the receiving chambers of the heart.  Blood enters the right atrium from the cranial and caudal vena cava and the coronary sinus and the left atrium from the four pulmonary veins.  The atria are found at the superior (cranial) end of the heart.  They are sometimes referred to as auricles.  They have thin walls compared to the ventricles.