ἀντίσχουσαν

This is a strong aorist fem acc participle. Why is the accent over the antepenult?

Thanks in advance.

Is this from present-tense ἀντίσχω, which is an alternative form of ἀντέχω?

http://www.perseus.tufts.edu/hopper/text?doc=Perseus%3Atext%3A1999.04.0057%3Aentry%3Da)nte%2Fxw

Right. I’m too trusting of Perseus. Thanks.