The anterior cardiac veins (or anterior veins of right ventricle) are a variable number of small veins (usually 2-5) which drain blood from the anterior portion of the right ventricle into the right atrium. The right marginal vein frequently opens into the right atrium, and is therefore sometimes regarded as belonging to this group. Unlike most cardiac veins, the anterior cardiac veins do not end in the coronary sinus; instead, they drain directly into the anterior wall of the right atrium.