..Starting node ..Aplasia/Hypoplasia of the proximal phalanx of the thumb (HP:0009629)
Term ID:
9629
Name:
Aplasia/Hypoplasia of the proximal phalanx of the thumb
Synonym:
Absent/small innermost thumb bone; Absent/underdeveloped innermost thumb bone
Definition:
This term applies if the proximal phalanx of the thumb is either small/hypoplastic or absent. 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.