The extensor digitorum is located in the back of the forearm. It contributes to pain in the back of the hand and middle finger which sometimes radiates up into the back of the wrist and the back of the forearm. Pain is occasionally felt in the front of the wrist, just below the palm.
The flexor digitorum profundus muscle is found in the front of the forearm. It can contribute to pain and twitching in the four fingers. It can affect one or any combination of the fingers. It can also cause trigger finger, where a finger will lock in a bent position.
The flexor digitorum superficialis is located in the front of the forearm. It contributes to pain in the four fingers, the palm, and occasionally the wrist. The muscle is a major contributor to trigger finger.