Flexor Digitorum Profundus & Superficialis: A Detailed Guide

The flexor digitorum profundus helps flex the fingers. The muscle begins in the upper piece of the ulna bone. It embeds at the distal phalanges in the tips of the fingers. The muscle’s paunch locates in the lower arm. Nonetheless, it views as a hand muscle since it utilizes for hand usefulness. The muscle’s long ligaments stretch out over the wrist and the metacarpals of the hand.

Alongside the flexor pollicis longus and the pronator quadratus, the muscle assists load up with trip the lower arm. For oxygenated blood, the flexor digitorum profundus muscle depends on the foremost interosseous course. The muscle innervates by the foremost interosseous and the ulnar nerves. In the event that either the nerves or the muscle itself endure injury, the fingers would lose their finesse.

Flexor Digitorum Profundus and Flexor Digitorum Superficialis

Grasp strength produces through extraneous flexor tendon and intrinsic muscle activation. In the investigation revealed here, we examined the hold-producing properties of the flexor digitorum profundus (FDP) and flexor digitorum superficialis (FDS) ligaments during grasp strength age.

flexor digitorum profundus

Source: wikimedia.org

Flexor Digitorum Profundus: Functions and Structure

  • It is the head holding muscle. It acts best when the wrist broaden. 
  • Flexor digitorum profundus is the sole flexors of Distal Interphalangeal (DIP) Joint of digit second to fifth. 
  • It likewise goes about as a flexor of the midcarpal (wrist), metacarpophalangeal, and proximal interphalangeal( PIP) joints of the file, center, ring, and little fingers alongside Flexor digitorum superficialis.
  • Since the lumbricals emerge from the flexor digitorum profundus ligaments and supplement the dorsal extensor developments of the proximal phalanges. Flexor digitorum profundus muscle helps the lumbricals in completely expanding the fingers at the interphalangeal joints and flexing the fingers at the metacarpophalangeal joints.


The upper appendage musculature gets from the dorsolateral cells of somites. It move into the appendage around the fourth week to frame muscles. With stretching of the appendage buds, the muscle tissue parts into flexor and extensor segments dictated by connective tissue got from the horizontal plate mesoderm.

The zone of polarizing action at the back fringe of the upper appendage secretes a sonic hedgehog to control front back patterning. Once the appendage bud shapes, the ventral essential rami enters into the mesenchyme. The middle and ulnar nerves frame by the ventral branch to at last stock the flexor digitorum profundus.

flexor digitorum profundus

Source: ytimg.com

Blood Supply and Lymphatic

The flexor digitorum profundus is provided by the front interosseous vein, which is a part of the normal interosseous course. The front interosseous supply route is joined by the palmar interosseous part of the middle nerve. And emits solid branches to the flexor digitorum profundus and flexor pollicis longus muscles.

The flexor digitorum profundus lymphatic waste is important for the upper appendage lymph framework, comprising shallow and profound vessels. The shallow vessels around the basilic vein go to the cubital lymph hubs. Which are proximal to the average epicondyle of the humerus.

Vessels around the cephalic vein go to the axillary lymph hubs. The profound lymphatic vessels likewise channel lymph from the flexor digitorum profundus and follow the significant profound veins, at the end ending in the humeral axillary lymph hubs.


Flexor digitorum profundus lies in the average piece of the lower arm flexor compartment. It is found profound to the flexor digitorum superficialis muscle along its whole course. In the lower arm, the middle nerve crosses the parallel piece of the foremost surface of the muscle. 

The ligaments of flexor digitorum profundus additionally lie profound to those of flexor digitorum superficialis. On their way towards the distal phalanges of the digits. Every one of the four ligaments goes through the stretch limited by the terminal slips of the flexor digitorum superficialis. The lumbrical muscles of the hand connect to the profound surfaces of the flexor digitorum profundus ligaments.

flexor digitorum profundus

Source: nfa5.com


It is the half breed muscle provided by two unique nerves: 

  • The average half (relates with ring and little fingers) innervates by the ulnar nerve
  • Parallel half (related with center and forefingers) by the front interosseous nerve (C8, T1)- engine part of the middle nerve. 

The horizontal piece of the flexor digitorum profundus muscle (relates with the list and center fingers) innervates by the front interosseous part of the middle nerve. The average piece of the muscle (relates to the ring and little fingers) innervates by the ulnar nerve (C8, T1). The flexor digitorum profundus is the lone flexor muscle that does not solely innervate by the middle nerve.

The middle nerve plunges between the flexor digitorum superficialis and the flexor digitorum profundus proximally. The foremost interosseous nerve branches from the middle nerve mostly down the lower arm and from the dorsal sidelong part of the middle nerve. The front interosseous nerve has just the engine working.


Close by the flexor pollicis longus and pronator quadratus. The flexor digitorum profundus muscle outlines the significant layer of the ventral lower arm muscles. The decussation of the flexor digitorum profundus tendons and the flexor digitorum superficialis (FDS) tendons occurs at the Camper chiasm.

Physiologic Variations 

The flexor digitorum profundus physiologic variations are reasons for unconstrained flexor ligament cracks as depicted in the writing. The two ulnar flexor digitorum profundus ligaments for the most part begin from a similar muscle stomach and separate in the lower arm or carpal passage.

Be that as it may, a few case reports have depicted a variation of the flexor digitorum profundus little finger ligament. And, the ligaments of the little and ring finger combine at the mid palmar level. This anatomic peculiarity inclines to flexor digitorum profundus ligament burst as the little finger ligament.  It is the most fragile point against shearing powers from the pulling pressure.

flexor digitorum profundus

Source: pinimg.com

Surgical Contemplations  For Flexor Digitorum Profundus

The volar way to deal with the flexor ligaments is significant for the most ideal presentation of the flexor ligaments inside their sinewy sheaths. This methodology is utilized for investigation and fix of the flexor digitorum profundus ligaments, fix of computerized nerves and vessels, and introduction of the sinewy flexor sheaths for seepage of discharge. 

Usable treatment for separation injury of the flexor digitorum profundus (shirt finger) incorporates direct ligament fix, ligament reinsertion with a dorsal catch, open decrease inside obsession of the break section, two-stage flexor ligament joining, and distal interphalangeal arthrodesis.

Direct ligament fix and ligament reinsertion with a dorsal catch is done in an intense injury setting (more noteworthy than three weeks) and forestalls the danger of distal interphalangeal (Plunge) flexion contracture or quadriga if more prominent than 1 cm progression of the flexor digitorum profundus ligament does not remedy.

Open decrease inside obsession of the broken part is accomplished for huge separation cracks with the related withdrawal of the ligament either to the Dunk joint or into the palm. Two-stage flexor ligament uniting of the flexor digitorum profundus is shown for persistent injury (more prominent than 3 months) with a full aloof scope of movement of the Plunge joint. Plunge arthrodesis is a rescue methodology in ongoing injury with constant firmness.

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Clinical Pertinence Of Flexor Digitorum Profundus

Lumbrical in addition to finger: When injury to the flexor digitorum profundus ligament distal to the lumbrical starting point happens by break or removal. It shows as a confusing augmentation of the interphalangeal joints when endeavoring to flex the finger. 

  • Quadriga: Since the flexor digitorum profundus tendons to the 5th,4th and third fingers have a common muscle stomach. The tendon is not able to move openly if that they interconnect with the different ligaments of the forefinger. This may prompt the patient not to have the option to make a full clenched hand and a related frail handle. This condition is known as quadriga. This may happen following attachment or scarring of FDP after crack and fix. 
  • Jersey finger: The condition in which crack of the flexor digitorum profundus ligament from the distal connection addition at the base of the distal phalanx driving no dynamic flexion of the distal interphalangeal joint known as Jersey’s finger.  Jersey’s finger is a zone 1 flexor ligament injury that includes the ring finger in 75% of cases. Which is a result of the way that FDP muscle midsection is in maximal constriction during strong distal interphalangeal joint expansion. 

Other Pertinence Of Flexor Digitorum Profundus

  • Anterior interosseous nerve (AIN) injury: AIN supplies three muscles in the lower arm: flexor pollicis longus (FPL), pronator quadratus (PQ), and the parallel portion of flexor digitorum profundus (FDP). The patient will be not able to play out an “alright” sign with the thumb or a positive Squeeze Hold test (Froment’s sign) because of loss of motion of the flexor pollicis longus and the flexor digitorum profundus muscles to flex the Plunge joint. 
  • Compartment disorder of lower arm: Compartment condition following supracondylar, ulnar, or range cracks deliveries through the technique named Fasciotomy.  Where both the shallow and profound volar compartments should deliver.
  • Ulnar hook hand distortion: Injury to the ulnar nerve at the distal district at the wrist level with the indications of hyperextension of MCP joints and flexion of IP joints of the ring and little finger.

Other Issues Of Flexor Digitorum Profundus

In instances of flexor digitorum profundus disorder seen in supracondylar, ulnar, or range cracks. The volar compartment of the lower arm delivers. The volar compartment condition presents as agony with inactive augmentation of the fingers and wrist. Fasciotomy of the lower arm perform, and both the shallow and profound volar compartments should deliver.

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