5 Signs of a Thumb Sprain
Source: Handcare
A sprained thumb is an injury to a ligament, which is a soft tissue that connects bones to each other at the joints to keep it stable, as opposed to a thumb fracture (break) which is an injury to the bone. The ulnar collateral ligament is the most injured ligament in the thumb. This particular ligament connects the thumb to the hand on the side closest to your index finger.
