Questions & Answers about Supercilium supra oculum est.
Because supercilium is the subject of the sentence: it is the thing being described.
In Supercilium supra oculum est, the basic structure is:
- supercilium = the eyebrow
- est = is
So supercilium is the thing that is somewhere, and subjects are normally put in the nominative case.
Also, supercilium is a neuter second-declension noun, and here it is nominative singular.
Because supra takes the accusative.
So in this sentence:
- supra = above
- oculum = eye, in the accusative singular
Even though English uses above the eye without showing any case ending, Latin marks the noun after supra with the accusative.
A learner might expect some kind of locative idea to use the ablative, but with supra, standard Latin uses the accusative.