has part has part characteristic of inheres in has modifier Short phalanx of the thumb Aplasia/Hypoplasia of the 1st metacarpal Short 1st metacarpal 2009-05-27T04:24:50Z In contrast to the proximal phalanges of the digits 2-5, the proximal phalanx of the thumb is embryologically equivalent to the middle phalanges of the other digits, whereas the first metacarpal is embryologically of phalangeal origin and as such equivalent to the proximal phalanges of the other digits. Short first metacarpals Shortened 1st long bone of hand HP:0010034 HP:0001190 A developmental defect characterized by reduced length of the first metacarpal (long bone) of the hand. First metacarpals hypoplastic Hypoplastic 1st metacarpal HP:0006141 UMLS:C1849311 First metacarpal hypoplasia Short first metacarpal HP:0001499 HP:0005898 Short metacarpal abnormal decreased length metacarpal bone of digit 1