Trigger finger is a form of Repetitive Strain Injury
It can be relatively mild with occasional snapping of the affected fingers, but can also be a severe dysfunction with locking of the finger.
As a result of improper use or occasionally linked to other conditions (arthritis for example) there have been changes (thickening or nodule development) to the tendon sheaths or the tendons themselves.
As with other forms of RSI, there is much we can offer to help you!
Link to RSI