http://www.mayfieldclinic.com/PE-AnatSpine.htm#.VdoxI5f9O1s ref. http://www.mayfieldclinic.com/PE-AnatSpine.htm#.VZSTeUb9O1s spinal cord is about 18 inches long Spine Anatomy posterior intraspinal canal ligament, the ligamentum flavum. Anatomy of the Spine http://www.mayfieldclinic.com/PE-AnatSpine.htm#.VZSTeUb9O1s