opisthionyoudaoicibaDictYouDict[opisthion 词源字典]
"The midpoint of the posterior border of the foramen magnum", Late 19th cent. From French opisthion from ancient Greek ὀπίσθιον hinder part, use as noun of neuter singular of ὀπισθίος belonging to the hinder parts from ὄπισθεν behind + -ιος, suffix forming adjectives.[opisthion etymology, opisthion origin, 英语词源]