serratus posterior vs serratus

serratus posterior and serratus both are nouns.

Word	Noun	Adjective	Verb	Adverb
serratus posterior	Yes	No	No	No
serratus	Yes	No	No	No

As nouns, serratus is a hypernym of serratus posterior; that is, serratus is a word with a broader meaning than serratus posterior:

serratus posterior: skeletal muscle that draws the rib cage backward and downward
serratus: any of several muscles of the trunk

Other hypernyms of serratus posterior include serratus muscles.

serratus posterior (noun)	serratus (noun)
skeletal muscle that draws the rib cage backward and downward	any of several muscles of the trunk