Flexor Hallucis Longus Trigger Points

Introduction

The flexor hallucis longus (FHL) is a key lower leg muscle responsible for big toe flexion and foot stabilization. When trigger points develop in this muscle, they can cause pain in the arch, big toe, and ankle, often mimicking plantar fasciitis, tarsal tunnel syndrome, or neuropathy.

Name and Area

  • Name: Flexor Hallucis Longus (FHL)

  • Area: Located on the posterior lower leg, running from the fibula to the distal phalanx of the big toe.

Indications

Flexor hallucis longus trigger points may contribute to:

  • Pain in the Big Toe and Arch (Mistaken for Plantar Fasciitis or Bunions)

  • Pain That Radiates to the Heel or Ankle (Can Mimic Achilles Tendinitis or Heel Spurs)

  • Tightness or Cramping in the Big Toe (Especially with Walking or Running)

  • Weakness in Toe Flexion (Difficulty Pushing Off While Walking or Running)

  • Pain That Increases When Wearing Tight Shoes or Walking Barefoot on Hard Surfaces

  • Aching or Burning Sensation in the Foot and Lower Leg After Long Periods of Standing

Pain from this muscle is often mistaken for plantar fasciitis, nerve compression, or metatarsalgia.

Muscle Action

  • Flexes the Big Toe (Hallux): Bends the big toe at the distal phalanx.

  • Assists in Foot Plantarflexion: Helps point the foot downward.

  • Supports the Medial Arch: Works with the tibialis posterior to maintain foot stability.

The FHL is crucial for balance, toe-off mechanics, and proper foot function during walking and running.

Signs and Symptoms

Individuals with flexor hallucis longus trigger points often report:

  • Pain in the Big Toe, Arch, and Inner Ankle

  • Difficulty Flexing the Big Toe (Pain When Pushing Off While Walking or Running)

  • Burning or Tingling Sensation in the Foot (Mistaken for Nerve Pain or Neuropathy)

  • Pain That Feels Worse After Long Periods of Walking or Standing

  • Toe Stiffness or Weakness, Especially in the Morning or After Activity

Pain worsens with prolonged standing, walking, or wearing unsupportive footwear.

Perpetuating Factors

Common causes of flexor hallucis longus trigger points include:

  • Wearing Tight or Narrow Shoes (E.g., High Heels, Cleats, or Dress Shoes)

  • Overuse From Running, Sprinting, or Jumping

  • Foot Instability Due to High Arches or Flat Feet

  • Walking or Standing for Long Periods on Hard Surfaces (Retail Workers, Runners, Hikers)

  • Toe-Curling Movements or Foot Strain from Certain Sports (Dancing, Ballet, or Soccer)

Trigger Point Referral Pattern

Trigger points in the flexor hallucis longus refer pain to:

  • The big toe (Mistaken for Bunions or Gout)

  • The inner ankle (Can Mimic Tarsal Tunnel Syndrome or Achilles Tendinitis)

  • The arch of the foot (Mistaken for Plantar Fasciitis or Arch Pain)

Pain from this muscle is often confused with plantar fasciitis, bunions, or nerve compression.

Differential Diagnosis

Flexor hallucis longus trigger points may be mistaken for:

  • Plantar Fasciitis (Pain in the Arch and Heel, Especially in the Morning)

  • Tarsal Tunnel Syndrome (Burning Pain and Numbness in the Foot and Toes)

  • Hallux Rigidus (Stiffness and Pain in the Big Toe Joint, Worsens with Movement)

  • Morton’s Neuroma (Pain Between the Toes with a "Pebble in the Shoe" Sensation)

  • Stress Fractures in the Metatarsals (Pain That Worsens with Impact Activities)

A thorough foot examination is necessary to rule out these conditions.

Associated Trigger Points

Flexor hallucis longus trigger points often co-exist with:

  • Tibialis Posterior (Pain Along the Inner Ankle and Foot, Affects Arch Support and Stability)

  • Flexor Hallucis Brevis (Big Toe Pain and Weakness in Toe Push-Off During Running and Walking)

  • Flexor Digitorum Longus (Pain in the Foot and Toes, Affects Toe Control and Push-Off Strength)

  • Peroneus Longus and Brevis (Lateral Foot and Ankle Pain, Can Affect Balance and Gait)

Anatomy and Innervation

Muscle Origin Insertion Innervation
Flexor Hallucis Longus Posterior fibula, interosseous membrane Base of the distal phalanx of the big toe Tibial nerve (L5–S2)

The FHL is innervated by the tibial nerve, which also controls toe flexion and foot stability.

Patient Examination

A comprehensive examination should include:

  • Palpation: Identify tender nodules along the posterior lower leg and base of the big toe.

  • Big Toe Flexion Strength Testing: Assess pain and weakness when curling the big toe against resistance.

  • Gait Analysis: Look for abnormal foot movement patterns while walking or running.

  • Footwear Assessment: Determine if improper shoes are contributing to symptoms.

Corrective Actions

Dry Needling

  • Dry needling can release trigger points in the flexor hallucis longus, reducing muscle tightness and improving foot mobility.

Manual Therapy

  • Trigger Point Release: Apply direct pressure to tight spots in the calf, ankle, and base of the big toe.

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

Stretching

  • Big Toe Flexor Stretch: Pull the big toe backward gently while keeping the foot relaxed.

  • Calf and Foot Stretch: Roll a tennis ball or massage ball under the foot to loosen tight muscles.

Strengthening Exercises

  • Toe Gripping Exercises: Strengthens the flexor hallucis longus and foot stabilizers.

  • Resistance Band Toe Flexion: Improves big toe control and push-off strength.

  • Calf Raises: Helps activate the foot and ankle stabilizers.

Postural and Footwear Adjustments

  • Wear Supportive Shoes with Proper Arch Support

  • Use Custom Orthotics to Improve Foot Alignment

  • Avoid Excessive Barefoot Walking on Hard Surfaces

Conclusion

The flexor hallucis longus plays a crucial role in big toe flexion and foot stability, but trigger points in this muscle can cause significant big toe, arch, and ankle 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.