The anatomy of the deep transverse metacarpal ligament was examined in
cadaveric dissections. Previously unreported findings were transverse
muscular slips from abductor digiti minimi that inserted into the med
ial border of the ligament and, in 1 case, an extension from the media
l half of the tendon of extensor carpi ulnaris that inserted into the
medial aspect of the ligament. Applied anatomy in relation to the dyna
mics of the transverse metacarpal arch is reviewed.