Flexor Digitorum Superficialis Anatomy Section 7

Flexor Digitorum Sublimis (FDS)

Origin: Humeral-ulnar head: Humerus (medial epicondyle via the common flexor tendon), ulnar collateral ligament (UCL) of the elbow joint, ulna (coronoid process, medial side), and intermuscular septa. Radial Head: Radius (oblique line on anterior surface).
Insertion: Four tendons arranged in two pairs: Superficial pair: Long and ring fingers, and deep Pair: Index and little fingers with inserting into the appropriate middle phalanx.
Innervation: Cervical root(s): C8–T1; Nerve: median nerve.
In the proximal forearm the median nerve is on the dorsal surface of the FDS.
The proximal flexor digitorum superficialis (FDS) has ulnar and radial heads.
Proximally FDS muscle gets blood supply from the radial and ulnar arteries.

Diagrams & Photos

Flexor Digitorum Superficialis (FDS) II - V
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 superficialis (FDS) is an extrinsic hand muscle that originates in the volar forearm.
FDS II, III, IV, & V are median nerve innervated.
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 one brevis going to the FDS.
At the Chiasma of Camper over the middle of the proximal phalanx the FDS splits into two slips which twist dorsally to reach their insertion sites at the base of the middle phalanx.
At the PIP joint the two slips of the FDS rest on the volar plate. The short vinculum of the FDS originates from the vessels between the two parts of “check rein ligaments” of the proximal volar plate.