The pectinate muscles (musculi pectinati) are parallel muscular ridges in the walls of the atria of the heart.

[citation needed] In the left atrium, the pectinate muscles are confined to the inner surface of its atrial appendage.

[citation needed] Pectinate muscles of the atria are different from the trabeculae carneae, which are found on the inner walls of both ventricles.

[citation needed] The pectinate muscles are so-called because of their resemblance to the teeth of a comb, as in pecten.

[citation needed] This article incorporates text in the public domain from page 529 of the 20th edition of Gray's Anatomy (1918)