Flexor digitorum superficialis (flexor digitorum sublimis) is an extrinsic flexor muscle of the fingers which lies in anterior compartment of forearm and causes flexion at the proximal interphalangeal joints.
The muscle originates from two heads the humeroulnar and radial. Between these two heads median nerve and ulnar artery pass.
Near wrist, it divides into four tendons which travel through the carpal tunnel formed by the flexor retinaculum. These tendons, along with those of flexor digitorum profundus, are enclosed by a common flexor sheath. The tendons attach to the anterior margins on the bases of the middle phalanges of the four fingers.
The tendons have a split (Camper’s Chiasm) at the end of them through which the tendons of flexor digitorum profundus pass.
The primary function of flexor digitorum superficialis is flexion of the middle phalanges of the fingers at the proximal interphalangeal joints, however under continued action it also flexes the metacarpophalangeal joints and wrist joint.