In trigger finger, also known as stenosing tenosynovitis (stuh-NO-sing ten-o-sin-o-VIE-tis), one of your fingers or your thumb gets stuck in a bent position and then straightens with a snap — like a trigger being pulled and released. If trigger finger is severe, your finger may become locked in a bent position. Often painful, trigger finger is caused by a narrowing of the sheath that surrounds the tendon in the affected finger. People whose work or hobbies require repetitive gripping actions are more susceptible. Trigger finger is also more common in women and in anyone with diabetes. Treatment of trigger finger varies depending on the severity.