From ꜣmꜥ(“perching bird”) + -t, so named because its attachment to the temporal bone was reminiscent of the claw of the ꜣmꜥ-bird grabbing something, as described in the Edwin Smith Papyrus 8.14–8.15.
Hannig, Rainer (1997) Großes Handwörterbuch Ägyptisch-Deutsch: die Sprache der Pharaonen (2800–950 v. Chr.) (Hannig-Lexica; 1), second edition, Mainz: Verlag Philipp von Zabern, →ISBN, page 9