has part has part Abnormality of thumb phalanx Duplication of thumb phalanx 2009-05-15T12:51:02Z Complete/partial duplication of phalanges of the thumb Duplicated thumbs HP:0009661 Duplicated thumb Complete or partial duplication of the phalanges of the thumb. Depending on the severity, the appearance on x-ray can vary from a notched phalanx (the duplicated bone is almost completely fused with the phalanx), a partially fused appearance of the two bones (bifid), two separate bones appearing side to side, or completely duplicated phalanges (proximal and distal phalanx of the thumb and/or 1st metacarpal). In contrast to the phalanges of the digits 2-5 (proximal, middle and distal), 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. Duplication of phalanx of thumb UMLS:C4021370 HP:0009942 Complete duplication of thumb phalanx Partial duplication of thumb phalanx Duplication of phalanx of hand