Peroneus Tertius Trigger Points

Introduction

The peroneus tertius is a small but important lower leg muscle responsible for foot dorsiflexion and eversion. When trigger points develop in this muscle, they can cause outer ankle pain, foot instability, and difficulty lifting the foot, often mimicking shin splints, ankle sprains, or nerve compression.

Name and Area

  • Name: Peroneus Tertius (Fibularis Tertius)

  • Area: Located on the outer lower leg, running from the distal fibula to the base of the fifth metatarsal.

Indications

Peroneus tertius trigger points may contribute to:

  • Pain on the Outer Ankle and Foot (Mistaken for Ankle Sprains or Peroneal Tendinitis)

  • Pain That Extends to the Front of the Shin (Can Mimic Shin Splints or Tibial Stress Syndrome)

  • Weakness in Foot Dorsiflexion (Difficulty Lifting the Foot, Can Contribute to "Foot Drop")

  • Pain or Instability When Walking or Running, Especially on Uneven Surfaces

  • Increased Risk of Tripping Due to Weak Toe Clearance During Walking

  • Pain That Worsens with Running, Jumping, or Wearing Unsupportive Shoes

Pain from this muscle is often mistaken for shin splints, ankle instability, or nerve compression syndromes.

Muscle Action

  • Dorsiflexes the Foot: Helps lift the foot upward, essential for walking and running mechanics.

  • Everts the Foot: Moves the foot outward, assisting in balance and ankle stability.

The peroneus tertius is crucial for ankle control, foot clearance during walking, and preventing ankle rolling.

Signs and Symptoms

Individuals with peroneus tertius trigger points often report:

  • Pain Along the Outer Shin and Ankle That Feels Like a Dull Ache or Sharp Sensation

  • Pain That Radiates to the Outer Foot (Can Feel Like a "Tugging" Sensation Near the Ankle)

  • Weakness in Foot Dorsiflexion (Difficulty Lifting the Foot While Walking or Running)

  • Pain When Walking Downhill or Running on Uneven Terrain

  • Frequent Ankle Rolling or Feeling of Instability

  • Pain or Fatigue in the Foot and Ankle After Prolonged Standing or Walking

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

Perpetuating Factors

Common causes of peroneus tertius trigger points include:

  • Excessive Running or Sprinting Without Proper Warm-Up (Overloads the Lower Leg Muscles)

  • Frequent Ankle Rolling or Sprains (Forces the Peroneals to Overwork for Stability)

  • Walking or Running on Uneven Surfaces (Increases Strain on the Outer Shin and Foot)

  • Wearing Unsupportive Shoes (Minimalist Footwear or High Heels Can Increase Strain on the Peroneals)

  • Tight Calves or Weak Tibialis Anterior (Causes Overuse of the Peroneus Tertius for Foot Lifting and Balance)

Trigger Point Referral Pattern

Trigger points in the peroneus tertius refer pain to:

  • The outer shin and lower leg (Mistaken for Shin Splints or Tibial Stress Syndrome)

  • The outer ankle and lateral foot (Can Mimic Peroneal Tendinitis or Ankle Ligament Sprains)

  • The top of the foot and base of the fifth metatarsal (Mistaken for Stress Fractures or Cuboid Syndrome)

Pain from this muscle is often confused with ankle instability, tibial stress syndrome, or nerve irritation.

Differential Diagnosis

Peroneus tertius trigger points may be mistaken for:

  • Shin Splints (Pain in the Front of the Lower Leg, Worse with Running or Impact Activities)

  • Peroneal Tendinitis (Pain and Swelling Along the Outer Ankle and Foot, Common in Runners and Walkers)

  • Tibialis Anterior Strain (Pain in the Shin and Ankle, Can Affect Foot Dorsiflexion and Balance)

  • Ankle Ligament Sprain (Pain and Swelling After a Twisting Injury, Often Due to Ankle Rolling)

  • Foot Drop (Neurological Condition Causing Weakness in Foot Dorsiflexion, Can Lead to Tripping and Instability)

A thorough ankle, foot, and lower leg examination is necessary to rule out these conditions.

Associated Trigger Points

Peroneus tertius trigger points often co-exist with:

  • Peroneus Longus and Brevis (Outer Foot and Ankle Pain, Affects Lateral Foot Stability and Gait Mechanics)

  • Tibialis Anterior (Shin and Foot Pain, Affects Dorsiflexion and Walking Mechanics)

  • Gastrocnemius and Soleus (Calf Tightness and Ankle Instability, Can Contribute to Foot Fatigue and Heel Pain)

  • Quadratus Plantae (Arch and Heel Pain, Can Resemble Plantar Fasciitis or Foot Cramps)

Anatomy and Innervation

Muscle Origin Insertion Innervation
Peroneus Tertius Distal third of the fibula Base of the fifth metatarsal Deep fibular nerve (L5–S1)

The peroneus tertius is innervated by the deep fibular nerve, which also controls foot dorsiflexion and ankle stability.

Patient Examination

A comprehensive examination should include:

  • Palpation: Identify tender nodules along the outer lower leg and base of the fifth metatarsal.

  • Resisted Foot Dorsiflexion and Eversion Testing: Assess pain and weakness when lifting the foot upward and outward against resistance.

  • Gait Analysis: Look for foot drop, ankle instability, or difficulty lifting the toes while walking.

  • Ankle Stability Testing: Rule out ligament sprains, stress fractures, or nerve compression.

Corrective Actions

Dry Needling

  • Dry needling can release trigger points in the peroneus tertius, reducing ankle tightness and improving foot control.

Manual Therapy

  • Trigger Point Release: Apply deep sustained pressure to tight spots along the outer shin and foot arch.

  • Massage Therapy: Helps improve circulation and reduce muscle tension in the peroneals.

Stretching

  • Peroneal Stretch: Sit with the leg extended and gently pull the foot inward to stretch the outer shin and ankle.

  • Calf Stretch Against a Wall: Helps reduce tension in the peroneals and surrounding muscles.

Strengthening Exercises

  • Resistance Band Foot Eversion and Dorsiflexion: Strengthens the peroneus tertius and improves ankle stability.

  • Single-Leg Balance Drills: Enhances proprioception and reduces ankle instability.

  • Calf Raises on an Uneven Surface: Engages the peroneals for better lateral foot control.

Postural and Footwear Adjustments

  • Wear Shoes with Proper Arch Support (Prevents Excessive Pronation and Ankle Instability)

  • Use Custom Orthotics If Needed (Provides Better Lateral Foot Stability)

  • Gradually Increase Running or Activity Intensity (Prevents Sudden Overuse of the Peroneus Tertius)

Conclusion

The peroneus tertius plays a crucial role in foot dorsiflexion, ankle stability, and lateral foot support, but trigger points in this muscle can cause significant outer ankle, shin, and foot pain. By incorporating dry needling, manual therapy, stretching, and strengthening exercises, individuals can reduce pain, improve mobility, and prevent chronic ankle dysfunction.

➡️ Learn more about Trigger Points

➡️ Explore our Trigger Point Index

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.