splenius vs splenius muscle

splenius and splenius muscle both are nouns.

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

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

splenius and splenius muscle: 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 (noun)	splenius muscle (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