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 is 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)
FDP & FDS
Palmar view showing FDP, FDS, Chiasma of Camper, Volar plate, and two major pulleys A1 and A2.
Palmar dissection at PIP joint level with flexion sheath removed. Note FDP and FDS tendons and the Chiasma of Camper.
Note the vinculum brevis attaching to the dorsal distal FDP.

Key Points

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 8.
The flexors also get nutrients from synovial fluid as well as their vincula blood supply.
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.
The vincula vessels attach to the dorsal surfaces of the FDP and FDS tendons. The distal vincula brevis goes from the neck of the middle phalanx and its transverse vascular arch to the dorsal surface of the FDP.