The flexor digitorum superficialis is the single muscle which makes up the intermediate layer of the muscles of the anterior compartment of the forearm.

It has two heads:

  • humero-ulnar head
  • radial head

Origin
  • Humeroulnar head: medial epicondyle of humerus (primary origin), and coronoid process of ulna
  • Radial head: anterior oblique line of radius
Insertion
Margins of the base of the middle phalanges of the index, middle, ring and little fingers.
Innervation
Median Nerve
Blood Supply
Ulnar artery
Antagonist
Extensor digitorum
Action The flexor digitorum superficialis produces flexion at the following joints:
  • Proximal interphalangeal joints: flexes digits 2-5 (primary action due to insertion)
  • Metacarpophalangeal joints (2-5)
  • Wrist