metacarpus (n.)youdaoicibaDictYouDict[metacarpus 词源字典]
1650s, Modern Latin, from Greek metakarpion, from meta- (see meta-) + karpos "wrist" (see carpus). Related: Metacarpal.[metacarpus etymology, metacarpus origin, 英语词源]
opponens pollicisyoudaoicibaDictYouDict
"A muscle of the hand, originating from the trapezium and flexor retinaculum and inserting into the first metacarpal, which serves to cup the palm and assist in the opposing of the thumb to the other fingers", Mid 18th cent. From scientific Latin opponens pollicis from classical Latin oppōnēns, + pollicis, genitive singular of pollex thumb.