Muqarna 为阿拉伯文音译，英文称为 squinch(es)，中文一般译为「突角拱」或「角拱」或「交角券」。「突角拱」的称法比较平常。

When you stand beneath one of the domes and look up, you will see how the myriad little arches, called "squinches" (Arabic, muqarna), effect the transition from the square base to the round dome above. This symbolizes the transition from the world below to the heavens above. So, even Islam, like the Christian cathedrals mentioned above, has its vertical dimension.
http://www.nmhschool.org/tthornton/mehistorydatabase/mosque_...

http://www.civil.fcu.edu.tw/ce.dictionary/search.asp?key=&pa...

http://www.xwhodesign.com/bbs/dispbbs.asp?boardID=11&RootID=...