NCIt definition : A muscle that originates on the distal border of the flexor retinaculum and the tubercles
of the scaphoid and trapezium, and inserts into the lateral aspect of the first metacarpal;
it is involved in the rotation and flexion of the thumb and is supplied by the recurrent
branch of the medial nerve and the superficial palmar branch of the radial artery.;
Alternative definition : CDISC: A muscle of the arm, in general extending from the distal border of the flexor
retinaculum and the tubercles of the scaphoid and trapezium, to the lateral aspect
of the first metacarpal; primary function is rotation and flexion of the thumb.;