Final answer:
Trigger finger is caused by inflammation and swelling within the carpal tunnel. Overuse of the muscle tendons or wrist injury can compress the nerve, leading to trigger finger.
Step-by-step explanation:
Trigger finger is caused by inflammation and swelling within the carpal tunnel, a passageway formed by the carpal bones and flexor retinaculum.
The tendons of nine muscles in the forearm and a major nerve pass through this narrow tunnel.
Overuse of the muscle tendons or wrist injury can lead to compression of the nerve, resulting in trigger finger.