Hypoplastic (short) proximal phalanx of the thumb. 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.
Synonyms:
exact_synonym:
Hypoplastic/small proximal phalanx of the thumb; Short proximal phalanges of thumb; Short proximal thumb bone; Short proximal thumb phalanx