No, the Muslim religion doesn't address that, but "law" is different from "custom." In a polygamous culture, a woman's closest ties are with her full brothers (same father AND mother). This is illustrated as far back as the Old Testament.
The status of a wife may be legally very constricted, but if her brothers are sensitive to the way their sister is treated, they may take drastic action against an abusive husband from outside the immediate family. Obviously there's a lot of socio-political subtext here!
Under Islamic law, a woman who's divorced is entitled to the refund of her dowry, and eligible for future marriage. It doesn't always work out that way in practice, though.
In a way, it's similar to Orthodox Jewish practice ... a woman can't initiate a divorce, but she has important rights, including financial rights, if she can GET a divorce.
Thanks for the information.