The seven liberal arts were divided into trivium and quadrivium. The easier half, trivium, gives rise to the adjective trivialis, which has connotations of simplicity and vulgarity. The adjective quadrivialis serves — in addition to referring to quadrivium — as an antonym to trivialis (or so I understood). The Latin word quadrivialis seems very rare, and so does the English counterpart "quadrivial".
When were these two adjectives, trivialis and quadrivialis introduced to Latin? Were they always opposite to each other (one meaning simple and the other meaning advanced), or did this contrast develop later? Was there a different established antonym for trivialis if quadrivialis was much rarer than trivialis? I would like to see these two adjectives and their histories compared. If a full account is available but too long to share here, I would much appreciate an outline and a link to further reading.
Searching for quadrivialis does produce some hits, but I was unable to track any discussion to reliable or more complete sources.