Infraspinatus Trigger Points

Introduction

The infraspinatus is a key rotator cuff muscle responsible for shoulder external rotation and stabilization. When trigger points develop in this muscle, they can cause deep shoulder pain, limited mobility, and pain radiating down the arm, often mimicking rotator cuff tears, frozen shoulder, or cervical radiculopathy.

Name and Area

  • Name: Infraspinatus

  • Area: Located on the posterior scapula (shoulder blade), spanning from the infraspinous fossa to the greater tubercle of the humerus.

Indications

Infraspinatus trigger points may contribute to:

  • Pain deep in the shoulder joint (mistaken for rotator cuff tear or frozen shoulder)

  • Pain that radiates down the arm, sometimes to the wrist (can mimic nerve compression or biceps tendinitis)

  • Restricted shoulder mobility (difficulty reaching behind the back or combing hair)

  • Pain when lifting the arm overhead (common in overhead athletes and weightlifters)

  • Weakness in shoulder external rotation (affects throwing, racquet sports, and weightlifting)

  • Pain when sleeping on the affected shoulder (common in side sleepers)

Pain from this muscle is often mistaken for rotator cuff injuries, cervical nerve compression, or biceps tendinitis.

Muscle Action

  • Externally Rotates the Shoulder: Turns the humerus outward, essential for overhead movements and stabilizing the shoulder joint.

  • Stabilizes the Shoulder: Works with other rotator cuff muscles to prevent dislocations and ensure joint stability.

The infraspinatus is crucial for shoulder strength, mobility, and injury prevention.

Signs and Symptoms

Individuals with infraspinatus trigger points often report:

  • Deep, aching pain in the shoulder, especially in the back and outer shoulder

  • Pain that extends down the arm toward the wrist (can mimic nerve pain or thoracic outlet syndrome)

  • Weakness when rotating the arm outward (difficulty holding objects away from the body)

  • Pain when reaching behind the back (common complaint when fastening a bra or reaching for a seatbelt)

  • Sharp or aching shoulder pain that worsens with overhead activities

  • Pain that worsens with sleeping on the affected shoulder

Pain worsens with repetitive overhead motions, external rotation, or prolonged use of the shoulder.

Perpetuating Factors

Common causes of infraspinatus trigger points include:

  • Repetitive overhead activities (throwing, swimming, racquet sports, weightlifting)

  • Poor shoulder mechanics (compensating for weak rotator cuff muscles or poor scapular control)

  • Sleeping on the affected shoulder (can compress and irritate the infraspinatus)

  • Prolonged forward shoulder posture (common in desk workers, cyclists, and drivers)

  • Previous shoulder injuries (history of rotator cuff strains or shoulder impingement can increase tension in the infraspinatus)

Trigger Point Referral Pattern

Trigger points in the infraspinatus refer pain to:

  • The back of the shoulder and outer arm (can mimic rotator cuff tears or shoulder bursitis)

  • The lateral forearm and hand (mistaken for cervical radiculopathy or carpal tunnel syndrome)

  • The front of the shoulder (can resemble biceps tendinitis or shoulder impingement syndrome)

Pain from this muscle is often confused with nerve compression, rotator cuff tears, or frozen shoulder.

Differential Diagnosis

Infraspinatus trigger points may be mistaken for:

  • Rotator cuff tears (weakness and pain in shoulder movements, worsens with overhead lifting)

  • Frozen shoulder (severe shoulder stiffness and limited range of motion)

  • Cervical radiculopathy (neck pain with radiating symptoms into the shoulder and arm)

  • Thoracic outlet syndrome (compression of the brachial plexus, leading to arm and hand pain)

  • Shoulder impingement syndrome (pain and pinching sensation when raising the arm overhead)

A thorough shoulder, cervical spine, and postural assessment is necessary to rule out these conditions.

Associated Trigger Points

Infraspinatus trigger points often co-exist with:

  • Teres minor (deep shoulder pain and weakness in external rotation, often confused with rotator cuff tears)

  • Supraspinatus (pain in the top of the shoulder, common in shoulder impingement and overuse injuries)

  • Trapezius (upper back and neck pain, can affect shoulder mobility and posture)

Deltoid (pain in the outer shoulder, contributes to weakness in shoulder abduction)

Anatomy and Innervation

Muscle Origin Insertion Innervation
Infraspinatus Infraspinous fossa of scapula Greater tubercle of humerus Suprascapular nerve (C5–C6)

The infraspinatus is innervated by the suprascapular nerve, which also controls shoulder external rotation and stabilization.

Patient Examination

A comprehensive examination should include:

  • Palpation: Identify tender nodules along the posterior scapula and outer shoulder.

  • Resisted Shoulder External Rotation Testing: Assess pain and weakness when rotating the arm outward against resistance.

  • Overhead Arm Mobility Testing: Look for pain or limitations when lifting the arm overhead.

  • Postural and Scapular Control Assessment: Rule out shoulder instability or compensatory movement patterns.

Corrective Actions

Dry Needling

  • Dry needling can release trigger points in the infraspinatus, reducing muscle tightness and improving shoulder function.

Manual Therapy

  • Trigger Point Release: Apply direct pressure to tight spots in the posterior scapula and outer shoulder.

  • Myofascial Release: Helps improve circulation and reduce muscle tension.

Stretching

  • Cross-Body Shoulder Stretch: Reach one arm across the chest and hold with the opposite hand to stretch the infraspinatus.

  • Wall Shoulder Stretch: Place the arm on a wall and slowly rotate the torso away to stretch the rotator cuff muscles.

Strengthening Exercises

  • External Rotation With Resistance Bands: Strengthens the infraspinatus and other rotator cuff muscles.

  • Scapular Retraction Drills: Helps improve shoulder stability and prevent overuse injuries.

  • Face Pulls: Engages the posterior shoulder and upper back for better posture and scapular control.

Postural and Movement Adjustments

  • Avoid sleeping on the affected shoulder (use a support pillow to reduce shoulder compression).

  • Ensure proper form during weightlifting (avoid excessive shoulder internal rotation or overloading the rotator cuff).

  • Use ergonomic workstation setups (prevent forward shoulder posture and reduce shoulder stress).

Conclusion

The infraspinatus plays a crucial role in shoulder external rotation and joint stabilization, but trigger points in this muscle can cause significant shoulder, arm, and upper back 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.