Answer;
-Pectinate muscles
Explanation;
-Pectinate muscles are shaped a little like hair, and their function is maxium atrial contraction with minimal muscle mass.The pectinate muscles (musculi pectinati) are parallel ridges in the walls of the atria of the heart. They are so-called because of their resemblance to the teeth of a comb as in pecten.
-The pectinate muscles are ridge like elevations of muscle. They are parallel to each other and resemble teeth of a comb. They are easily observed inside the right atrium.
