Origin: Upper 3/4 of the anterior and medial surface of the ulna, interosseous membrane and deep fascia of the forearm. 

Insertion: 4 tendons (1 to each finger) to palmar surface of base of distal phalanx, after passing through tendon of flexor digitorum superficialis.

Isolated function: Assists in concentric acceleration of flexion of proximal interphalangeal and metacarpophalangeal joints.

Integrated function:
-Assists in eccentric deceleration of extension of proximal interphalangeal and metacarpophalangeal joints.
-Assists in dynamic stabilization of the lateral 4 phalanges.

Nerve Supply: Nerve to portion of muscle which correlates with index and middle fingers, anterior interosseous branch of the median, C8, T1; nerve to portion of muscle which correlates with ring and little fingers, ulnar, C8, T1.