More often than not, it emanates from a repeated movement or forceful use within your finger or thumb. Tendons are fibrous cords that attach muscle to bone. Each and every tendon is surrounded by a protecting sheath.  You should submit your inquiry in English or Mandarin utilizing the sort below. https://www.theorthopaedicandpainpractice.com/why-cant-i-straighten-the-tip-of-my-finger/