extensor vs striated muscle

extensor and striated muscle both are nouns.

Word	Noun	Adjective	Verb	Adverb
extensor	Yes	No	No	No
striated muscle	Yes	No	No	No

As nouns, striated muscle is a hypernym of extensor; that is, striated muscle is a word with a broader meaning than extensor:

extensor: a skeletal muscle whose contraction extends or stretches a body part
striated muscle: a muscle that is connected at either or both ends to a bone and so move parts of the skeleton; a muscle that is characterized by transverse stripes

Other hypernyms of extensor include skeletal muscle.

extensor (noun)	striated muscle (noun)
a skeletal muscle whose contraction extends or stretches a body part	a muscle that is connected at either or both ends to a bone and so move parts of the skeleton; a muscle that is characterized by transverse stripes