The trabeculae carneae are rounded or irregular muscular columns which project from the inner surface of the right and left ventricle of the heart. These are different from the pectinate muscles, which are present in the atria of the heart. In development, trabeculae carneae are among the first of the cardiac structures to develop in the embryonic cardiac tube. Throughout development some trabeculae carneae condense to form the myocardium, papillary muscles, chordae tendineae, and septum.