Heart: Right atrium (English)

Interior of the right atrium with its anterior wall is reflected. The internal surface of the anterior wall has a roughened appearance due to the presence of the pectinate muscles. These are folds of muscle arranged in a comb-like fashion around the region of the right auricle which function to act as a volume reservoir, increasing the capacity of the right atrium during times of dilatation. The remaining walls of the right atrium are smooth and offer the appreciation of several anatomical landmarks: the fossa ovalis, valves of the inferior vena cava and coronary sinus, as well as the right atrioventricular orifice.