tentorial sinus vs sinus rectus

tentorial sinus and sinus rectus both are nouns.

Word	Noun	Adjective	Verb	Adverb
tentorial sinus	Yes	No	No	No
sinus rectus	Yes	No	No	No

As nouns, tentorial sinus and sinus rectus are synonyms defined as:

Other synonyms of tentorial sinus include straight sinus.

tentorial sinus (noun)	sinus rectus (noun)
an unpaired sinus of the dura mater	an unpaired sinus of the dura mater