Biceps Femoris Trigger Points

Introduction

The biceps femoris is one of the three hamstring muscles located at the back of the thigh. It plays a crucial role in knee flexion, hip extension, and lateral leg stability. When trigger points develop in this muscle, they can cause pain in the back of the thigh, knee, and even the lower leg. These trigger points can mimic sciatica, making accurate diagnosis and treatment essential.

Name and Area

  • Name: Biceps Femoris

  • Area: Posterior thigh, running from the ischial tuberosity and femur to the fibular head.

Indications

Biceps femoris trigger points may contribute to:

  • Pain in the Back of the Thigh (often deep and aching)

  • Outer Knee Pain

  • Pain That Radiates to the Calf (Mimicking Sciatica)

  • Tightness in the Hamstrings (Especially in the Lateral Side)

  • Discomfort When Walking or Running

Pain is often worse when sitting for long periods or after intense lower-body workouts.

Muscle Action

  • Knee Flexion: Bends the knee.

  • Hip Extension (Long Head): Moves the thigh backward.

  • Lateral Rotation of the Tibia (When Knee is Flexed): Helps control leg movement.

The biceps femoris works alongside the other hamstring muscles (semitendinosus and semimembranosus) but differs in its ability to externally rotate the lower leg.

Signs and Symptoms

Individuals with biceps femoris trigger points often report:

  • Deep, Aching Pain in the Back of the Thigh

  • Sharp Pain on the Outer Knee (Lateral Side)

  • Radiating Pain Down to the Calf (Often Mistaken for Sciatica)

  • Tightness or Restricted Knee Flexion

  • Pain That Worsens with Sprinting, Cycling, or Squatting

Perpetuating Factors

Common causes of biceps femoris trigger points include:

  • Overuse from Running or Cycling (Particularly Sprinting or Hill Running)

  • Sudden Hamstring Strain or Tear (Common in Sports Like Soccer and Basketball)

  • Sitting with the Knee Bent for Prolonged Periods

  • Weak Glute Muscles Leading to Overuse of the Hamstrings

  • Tight Quadriceps or Hip Flexors, Forcing the Hamstrings to Work Harder

Trigger Point Referral Pattern

Trigger points in the biceps femoris typically refer pain to:

  • The posterior thigh

  • The lateral knee

  • The outer calf, sometimes extending to the ankle

Pain from these trigger points can sometimes be mistaken for sciatic nerve compression.

Differential Diagnosis

Because biceps femoris trigger points can cause thigh, knee, and calf pain, they may be mistaken for:

  • Sciatica (Lumbar Nerve Root Compression)

  • IT Band Syndrome (Lateral Knee Pain)

  • Popliteus Dysfunction (Pain Behind the Knee)

  • Lateral Meniscus Injury

  • Hamstring Tendinopathy or Partial Tear

A careful examination can help differentiate between nerve, joint, and muscle-related conditions.

Associated Trigger Points

Biceps femoris trigger points often co-exist with:

  • Gluteus Maximus (Hip Extension Dysfunction)

  • Piriformis (Can Cause Sciatic-Like Symptoms)

  • Vastus Lateralis (Outer Thigh and Knee Pain)

  • Gastrocnemius (Calf Tightness and Pain)

Anatomy and Innervation

  • Origin:

    • Long Head: Ischial tuberosity

    • Short Head: Linea aspera of the femur

  • Insertion: Fibular head and lateral condyle of the tibia

  • Innervation:

    • Long Head: Tibial portion of the sciatic nerve (L5–S2)

    • Short Head: Common peroneal nerve (L5–S2)

This dual innervation makes biceps femoris unique among the hamstring muscles, as the short head is controlled by the common peroneal nerve instead of the tibial nerve.

Patient Examination

A thorough examination should include:

  • Palpation: Identify tender nodules along the posterior thigh and near the fibular head.

  • Knee Flexion Strength Tests: Assess hamstring activation and pain response.

  • Stretching Response: Evaluate tightness when attempting a hamstring stretch.

  • Gait Analysis: Check for compensatory movement patterns.

Corrective Actions

Manual Therapy

  • Trigger Point Release: Apply sustained pressure over active trigger points.

  • Soft Tissue Mobilization: Reduce fascial restrictions along the posterior thigh.

Stretching

  • Seated Hamstring Stretch: Extend the leg and reach forward, keeping the knee straight.

  • Standing Forward Bend: Slowly bend forward at the hips while keeping the knees slightly bent.

Strengthening Exercises

  • Nordic Hamstring Curls: Strengthens eccentric hamstring control.

  • Glute Bridges: Improves posterior chain activation to reduce hamstring overuse.

  • Single-Leg Romanian Deadlifts: Builds hamstring strength while enhancing flexibility.

Postural and Biomechanical Adjustments

  • Improve Hip Mobility: Reduces compensatory strain on the hamstrings.

  • Strengthen the Glutes: Balances posterior chain function.

  • Correct Running Form: Prevents overuse injuries.

Field Details
Name & Area Biceps Femoris; Posterior thigh, spanning ischium to fibula
Indications Posterior thigh pain, lateral knee pain, outer calf discomfort
Muscle Action Knee flexion, hip extension (long head), lateral tibial rotation
Signs & Symptoms Tight hamstrings, pain when running or sitting, sciatica-like symptoms
Perpetuating Factors Sprinting, cycling, prolonged sitting, weak glutes, tight quads
Trigger Point Referral Posterior thigh, lateral knee, outer calf
Differential Diagnosis Sciatica, IT band syndrome, popliteus dysfunction, meniscus injury
Associated TrPs Gluteus maximus, piriformis, vastus lateralis, gastrocnemius
Anatomy & Innervation Sciatic nerve (L5–S2); tibial and common peroneal divisions
Corrective Actions Manual therapy, stretching, strengthening, gait correction

Summary Table: Biceps Femoris 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.