The term terminal filament .refers to a strand of connective tissue identified by dissection in vertebrates. Surrounded by the cauda equina, it extends from the end of the spinal cord to the lower end of the spinal canal. ( Carpenter-1983 ). Historically it was believed to be a nerve or an intertwined pair of nerves, hence the obsolete synonym 'unpaired nerve' ( Swanson-2014 ).