central nervous system vs medulla spinalis

central nervous system and medulla spinalis both are nouns.

Word	Noun	Adjective	Verb	Adverb
central nervous system	Yes	No	No	No
medulla spinalis	Yes	No	No	No

central nervous system (noun)	medulla spinalis (noun)
the portion of the vertebrate nervous system consisting of the brain and spinal cord	a major part of the central nervous system which conducts sensory and motor nerve impulses to and from the brain; a long tubelike structure extending from the base of the brain through the vertebral canal to the upper lumbar region