Alternative definition : CDISC: A muscle of the hand that extends from the capitate and bases of the second
and third metacarpals for the oblique head, and the anterior surface of body of the
third metacarpal for the transverse head, to the base of proximal phalanx and extensor
hood of the thumb; primary function is to draw the first metacarpal laterally to oppose
the thumb toward the center of palm and rotate it medially.;