( Doctors ( often ( ( refer ( to ( ( the backbone ) ( as ( ( ( ( ( ( the spine ) , ) ( spinal column ) ) , ) or ) ( vertebral column ) ) ) ) ) ) . ) ) )
(ROOT (S (NP (NNS Doctors)) (ADVP (RB often)) (VP (VBP refer) (PP (TO to) (NP (NP (DT the) (NN backbone)) (PP (IN as) (NP (NP (DT the) (NN spine)) (, ,) (NP (JJ spinal) (NN column)) (, ,) (CC or) (NP (JJ vertebral) (NN column))))))) (. .)))
Doctors often refer to the backbone as the spine, spinal column, or vertebral column .
(ROOT (S (NP (NNP Backbone)) (VP (VBZ is) (NP (NP (DT another) (NN name)) (PP (IN for) (NP (DT the) (JJ vertebral) (NN column))))) (. .)))
Backbone is another name for the vertebral column.