Flexor digitorum superficialis is an extrinsic flexor muscle of the fingers. The bulk of the muscle is in the anterior of the forearm.
Like most flexors of the arm, it is supplied by the median nerve. Its blood comes from the ulnar artery . The proximal attachment includes the median epicondyle of the humerus as well as parts of the radius and ulna.
Four long tendons come off this muscle, and travel through the carpal tunnel. They then attach to the base of the proximal phlanges on the four fingers. These tendons have a split, or a hole, at the end of them through which the tendons of flexor digitorum profundus will travel.