NCIt definition : The first and most medial of five miniature long bones located in the palm of the
hand, which articulates proximally with the trapezium of the carpus at the carpometacarpal
joint and distally with the thumb phalanx at the metacarpophalangeal joint.;
Alternative definition : CDISC: The first of the five long bones located in the palm of the hand, as counted
from the thenar side of the hand; it articulates proximally with the trapezium and
distally with the thenar phalanx (thumb).;