Final answer:
The prominent muscular ridges along the inner surface of the auricles and the anterior wall of the right atrium are called the pectinate muscles. These feature prominently on the right atrium and auricle but are only found in the auricle of the left atrium.
Step-by-step explanation:
The features described as prominent muscular ridges that extend along the inner surface of the auricles and the anterior wall of the right atrium are known as the pectinate muscles. These structures are unique to the right atrium and its extension, the right auricle, in the heart. The smooth walls of the right atrium contain the fossa ovalis medially, while the pectinate muscles form a series of parallel ridges on the anterior surface. Unlike the right atrium, the left atrium possesses pectinate muscles only within its auricle, not the main chamber.