 Articulated vertebrae from the holotype specimen possess blade like neural spines that are greatly enlarged, although not nearly to the extent that can be seen in more derived sphenacodontds such as "Dimetrodon" and "Secodontosaurus", in which they form a large sail.The pelvis is nearly identical to that of "Dimetrodon".As suggested in the original description of the genus, "Ctenorhachis" may represent a short-spined sexual dimorph, although the authors find this unlikely.