By Edward Fink, M.D. Trigger thumb arises when the sheath surrounding the tendon controlling thumb flexion becomes constricted and does not allow the tendon to glide freely as the thumb flexes and extends. This condition may occur in any digit and can arise from repeated trauma to the base of the thumb, although most often there is no precipitating cause. The tendon … [Read more...] about Medical Advice Re: ‘Trigger’ and ‘Gamekeeper’s’ Thumb