What causes "lock" or "trigger" finger?

Hi Anon,

Welcome to EmpowHER.  The cause of trigger finger is a narrowing of the sheath that surrounds the tendon in the affected finger. Tendons are fibrous cords that attach muscle to bone.  The tenosynovium releases lubricating fluid that allows the tendon to glide smoothly within its protective sheath as you bend and straighten your finger.  But if the tenosynovium becomes inflamed frequently or for long periods, the space within the tendon sheath can become narrow and constricting. The tendon can't glide through the sheath easily, at times catching the finger in a bent position before popping straight.

I've included a link that might be helpful

https://www.empowher.com/condition/trigger-finger

Best,

Daisy