A finger contusion, also known as a bruise, occurs when soft tissue in the finger is crushed, but the skin doesn't break. This can happen from a bump, twist, fall, or crush injury, such as a door crushing the finger or a heavy object falling on the nail bed. When this happens, small blood vessels near the skin's surface break and blood leaks into the tissues under the skin, causing a black-and-blue discoloration. As the bruise heals, the color may change to purplish black, reddish blue, or yellowish green