Index, Long, Ring, & Little Flexor Digitorum Profundus Anatomy

Flexor Digitorum Profundus (FDP)

Origin: Ulna (proximal 3/4 of anterior and medial shaft; medial coronoid process), interosseous membrane (ulnar).
Insertion: Four tendons to digits 2–5 (distal phalanges, at base of palmar surface). Note index finger tendon is distinct in its course
Innervation: Cervical root(s): C8–T1; C8–T1; Nerve: median nerve, digits 2–3; ulnar nerve, digits 4–5.
The FDP tendon’s blood supply in forearm is from ulnar artery primarily and in the finger from the digital arteries.
To facilitate gliding (sliding), the FDP tendons are covered by internal and external synovial sheaths.
The synovial sheaths of the index, long, and ring fingers beginning at the level of the metacarpal neck and A1 pulley. The sheath of the thumb and little fingers connect to the radial and ulnar bursa respectively.

Diagrams & Photos

Flexor Digitorum Profundus (FDP II-V)
The yellow oval outlines the parts of the flexor digitorum profundi that are located in section 7.
In this dissection the tenosynovium and pulleys have been remove. The superficial FDS tendons and the more dorsal FDP tendons 2, 3, & 5 are seen. Note the 4th FDP tendon is dorsal to FDS 4 and not visible.

Key Points

The flexor digitorum profundus (FDP) is an extrinsic hand muscle that originates in the volar forearm.
FDP II & III (median nerve innervated) to FDP IV & V (ulnar nerve innervated)
The FDP tendons are the origin of the lumbrical muscles. The lumbrical origins are located in palmar Section 7 and 8.
The flexors also get nutrients from synovial fluid, local vessels, and in the finger from the vincula blood supply.
In the digit the FDP gets its blood supply from the vincula longus and brevis. The vincula vessels originate from the transverse branches of the digital arteries.
There are two vinculum longus and two vinculum brevis with one longus and brevis going to the FDS and two others to the FDP.