The Oxford Thesaurus An A-Z Dictionary of Synonyms - spine n.

1) backbone, spinal column, vertebrae: He can't stand up straight - he has curvature of the spine. 2) thorn, needle, barb, spike, spur, prong, quill, ray, barbel, bristle, prickle, Technical barbule, spicule or spiculum or spicula: The surface of the sea urchin is covered with needle-like spines.