Flexor Digitorum Profundus Trigger Points

Introduction

The flexor digitorum profundus (FDP) is a key forearm muscle responsible for deep finger flexion and grip strength. When trigger points develop in this muscle, they can cause pain in the forearm, wrist, palm, and fingers, often mimicking carpal tunnel syndrome, arthritis, or nerve compression.

Name and Area

  • Name: Flexor Digitorum Profundus (FDP)

  • Area: Located on the deep anterior forearm, running from the ulna to the distal phalanges of digits 2–5.

Indications

Flexor digitorum profundus trigger points may contribute to:

  • Pain in the Palm, Wrist, and Fingers (Mistaken for Carpal Tunnel Syndrome or Arthritis)

  • Pain That Radiates to the Tips of the Fingers (Can Mimic Nerve Compression or Tendinitis)

  • Weakness in Grip Strength (Difficulty Holding Objects, Writing, or Typing)

  • Pain When Curling the Fingers or Making a Fist (Common in Office Workers, Musicians, and Rock Climbers)

  • Forearm Fatigue or Cramping with Repetitive Use (E.g., Knitting, Gardening, Playing an Instrument, Weightlifting)

  • Pain That Worsens with Gripping, Writing, or Typing for Extended Periods

Pain from this muscle is often mistaken for carpal tunnel syndrome, arthritis, or tendon injuries.

Muscle Action

  • Flexes the Fingers (Digits 2–5): Bends the fingers at the distal interphalangeal (DIP) joints.

  • Assists in Wrist Flexion: Helps stabilize the wrist while gripping objects.

The FDP is essential for grasping, fine motor tasks, and hand dexterity.

Signs and Symptoms

Individuals with flexor digitorum profundus trigger points often report:

  • Pain in the Palm, Wrist, and Fingertips

  • Weakness in Finger Flexion and Grip Strength

  • Pain That Worsens with Repetitive Hand Movements (Typing, Writing, Sewing, Playing Guitar, Using Hand Tools)

  • Forearm Tightness or Cramping (Particularly After Extended Use of the Hands)

  • Difficulty Fully Extending the Fingers After Gripping or Holding an Object for a Long Time

Pain worsens with repetitive gripping, finger flexion, or prolonged hand use.

Perpetuating Factors

Common causes of flexor digitorum profundus trigger points include:

  • Repetitive Finger and Wrist Movements (Typing, Gaming, Playing Instruments, Writing, Knitting, Weightlifting)

  • Frequent Use of a Computer Mouse or Touchscreen Devices (Sustained Finger Flexion Without Support)

  • Prolonged Hand Grip or Holding Objects for Extended Periods (Driving, Holding a Phone, Steering Wheel Grip, Cooking)

  • Overuse in Racquet Sports (Tennis, Badminton, Squash, or Rock Climbing)

  • Poor Ergonomics (Awkward Wrist Position While Using a Keyboard, Phone, or Mouse)

Trigger Point Referral Pattern

Trigger points in the flexor digitorum profundus refer pain to:

  • The palm and wrist (Mistaken for Carpal Tunnel Syndrome or Wrist Tendinitis)

  • The fingertips (Can Resemble Nerve Compression or Arthritis)

  • The forearm and elbow (Mistaken for Golfer’s Elbow or Ligament Sprains)

Pain from this muscle is often confused with wrist arthritis, carpal tunnel syndrome, or overuse injuries.

Differential Diagnosis

Flexor digitorum profundus trigger points may be mistaken for:

  • Carpal Tunnel Syndrome (Pain, Numbness, and Tingling in the Hand and Fingers, Particularly at Night)

  • Median Nerve Entrapment (Pain, Weakness, or Numbness in the Forearm and Hand)

  • Wrist Flexor Tendinitis (Pain and Stiffness in the Wrist and Forearm After Repetitive Use)

  • Golfer’s Elbow (Medial Epicondylitis – Inner Elbow Pain That Affects the Wrist and Hand)

  • Osteoarthritis or Rheumatoid Arthritis (Pain and Stiffness in the Finger Joints, Especially in the Morning)

A thorough hand, wrist, and forearm examination is necessary to rule out these conditions.

Associated Trigger Points

Flexor digitorum profundus trigger points often co-exist with:

  • Flexor Digitorum Superficialis (Pain in the Palm and Fingers, Weak Grip Strength)

  • Flexor Carpi Ulnaris (Pain on the Inner Wrist and Hand, Affects Grip Strength)

  • Pronator Teres (Pain in the Forearm and Wrist, Weakness in Forearm Rotation)

  • Extensor Digitorum (Pain in the Back of the Hand and Fingers, Affects Finger Extension)

Anatomy and Innervation

Muscle Origin Insertion Innervation
Flexor Digitorum Profundus Upper three-fourths of the ulna, interosseous membrane Distal phalanges of digits 2–5 Median nerve (digits 2 & 3, C8–T1); Ulnar nerve (digits 4 & 5, C8–T1)

The FDP is innervated by both the median and ulnar nerves, which also control finger flexion and grip strength.

Patient Examination

A comprehensive examination should include:

  • Palpation: Identify tender nodules along the forearm, near the wrist and palm.

  • Resisted Finger Flexion Testing: Assess pain and weakness when curling the fingers against resistance.

  • Grip Strength Testing: Determine if pain affects endurance when holding objects for long periods.

  • Median and Ulnar Nerve Compression Testing: Rule out nerve-related causes of wrist and hand pain.

Corrective Actions

Dry Needling

  • Dry needling can release trigger points in the flexor digitorum profundus, reducing muscle tightness and improving mobility.

Manual Therapy

  • Trigger Point Release: Apply direct pressure to tight spots along the forearm and wrist flexors.

  • Massage Therapy: Helps improve circulation and reduce forearm tension.

Stretching

  • Finger Flexor Stretch: Extend the arm with the palm facing upward, gently pull the fingers toward the body.

  • Forearm Rotation Stretch: Slowly rotate the wrist through supination and pronation to improve mobility.

Strengthening Exercises

  • Finger Flexion With Resistance Bands: Strengthens the flexor digitorum profundus and surrounding hand muscles.

  • Grip Strength Drills: Improves forearm endurance and function.

  • Eccentric Finger Flexion Exercises: Helps build strength while reducing tension.

Postural and Ergonomic Adjustments

  • Modify Keyboard and Mouse Positioning (Reduce Wrist and Finger Strain)

  • Use an Ergonomic Mouse or Wrist Support (Prevents Overuse Injuries)

  • Take Frequent Breaks During Repetitive Tasks (Allows Hand and Forearm Muscles to Recover)

Conclusion

The flexor digitorum profundus plays a crucial role in finger flexion and grip strength, but trigger points in this muscle can cause significant wrist, hand, and forearm pain. By incorporating dry needling, manual therapy, stretching, and strengthening exercises, individuals can reduce pain, improve mobility, and prevent future dysfunction.

➡️ Learn more about Trigger Points

Sources:

  • Travell, J. G., & Simons, D. G. (1983). Myofascial Pain and Dysfunction: The Trigger Point Manual (2nd ed.). Williams & Wilkins.

  • Simons, D., & Travell, J. (1999). The Trigger Point Manual, Volume 2: The Lower Extremities. Williams & Wilkins.