splenius muscle vs splenius

splenius muscle and splenius both are nouns.

Word	Noun	Adjective	Verb	Adverb
splenius muscle	Yes	No	No	No
splenius	Yes	No	No	No

As nouns, splenius muscle and splenius are synonyms defined as:

splenius muscle and splenius: either of two flat muscles that extend from the upper vertebrae to the base of the skull and serve to rotate or flex or extend the head and neck

splenius muscle (noun)	splenius (noun)
either of two flat muscles that extend from the upper vertebrae to the base of the skull and serve to rotate or flex or extend the head and neck	either of two flat muscles that extend from the upper vertebrae to the base of the skull and serve to rotate or flex or extend the head and neck