The Tuck Sign helps the examiner to distinguish between a dorsal ganglion and dorsal extensor tendon tenosynovitis. Tenosynovium is attached to the extensor tendons. When the patient extends the fingers the tenosynovial tissue moves proximally with the tendons. In combined maximal finger and wrist extension the abnormal tenosynovium and dorsal skin "tuck" under the extensor retinaculam of the wrist. The Tuck sign distinguishes hypertrophic synovium from a dorsal ganglion which does not move with the tendons.