What muscles can be affected by an inflamed dorsal scapular nerve?

Muscles Affected by an Inflamed Dorsal Scapular Nerve

An inflamed dorsal scapular nerve primarily affects the rhomboid major, rhomboid minor, and levator scapulae muscles. These muscles are responsible for scapular retraction, elevation, and stabilization of the medial border of the scapula.

Anatomical Considerations

The dorsal scapular nerve (DSN) typically:

• Originates from the C5 nerve root of the brachial plexus 1
• Takes one of two anatomical paths around the middle scalene muscle:
  • Piercing-type: passes through the middle scalene muscle (more common)
  • Anterior-type: runs in front of the middle scalene muscle 2
• Travels posteriorly to innervate the rhomboid muscles and levator scapulae

Specific Muscles Affected

1. Rhomboid Major

   • Function: Retracts and rotates the scapula
   • Location: Between T2-T5 vertebrae and medial border of scapula
   • Clinical impact: Weakness leads to lateral winging of the scapula

2. Rhomboid Minor

   • Function: Retracts and elevates the scapula
   • Location: Between C7-T1 vertebrae and medial border of scapula
   • Clinical impact: Weakness contributes to scapular instability

3. Levator Scapulae

   • Function: Elevates the scapula and rotates its inferior angle medially
   • Location: Between C1-C4 transverse processes and superior angle of scapula
   • Clinical impact: Weakness affects shoulder elevation and stability

Clinical Presentation of Dorsal Scapular Nerve Inflammation

When the dorsal scapular nerve is inflamed, patients typically present with:

• Winging of the medial border of the scapula with lateral rotation of its inferior angle 1
• Pain and discomfort in the neck, shoulder, and interscapular region 3
• Weakness in scapular retraction and elevation
• Difficulty with activities requiring arm elevation above 90° 1
• Potential neuropathic pain components 1

Common Causes of Dorsal Scapular Nerve Inflammation

1. Compression Sites:

   • Middle scalene muscle (traditional site) 3
   • Dynamic compression by the proximal part of the medial border of the scapula during arm elevation above 90° 1
   • Entrapment between muscle planes

2. Precipitating Factors:

   • Occupations involving heavy physical work
   • Sports requiring arm exertion (dancing, boxing, gymnastics) 1
   • Iatrogenic injury (e.g., trigger point injections) 4

Diagnostic Considerations

Diagnosis of dorsal scapular nerve inflammation is confirmed through:

• Electroneuromyographic testing showing denervation of rhomboid muscles 1
• Physical examination revealing reduced shoulder retractor muscle strength
• Nerve conduction studies showing low amplitude and delayed latency 4

Management Approaches

For an inflamed dorsal scapular nerve, treatment should focus on:

1. Physical Therapy:

   • Range of motion exercises to prevent further stiffness
   • Gentle stretching and mobilization techniques
   • Eccentric strengthening exercises to stimulate collagen production 5

2. Pain Management:

   • Topical NSAIDs for localized pain
   • Local application of heat before exercise sessions 5
   • Acetaminophen as first-line analgesic

3. Advanced Interventions:

   • Ultrasound-guided hydrodissection has been reported as successful in some cases 6
   • In severe cases, surgical decompression of the nerve may be considered 3

Prognosis

Complete recovery from dorsal scapular nerve inflammation can be challenging:

• Total correction of scapular winging is not always achieved 1
• Residual neuropathic pain may persist in some patients
• Specialized rehabilitation with a multidisciplinary approach offers the best outcomes 1

Clinical Pitfalls to Avoid

• Misdiagnosing as cervical radiculopathy or thoracic outlet syndrome
• Overlooking the possibility of dynamic compression during arm elevation
• Performing trigger point injections into the rhomboid muscles without considering the course of the dorsal scapular nerve 4
• Relying solely on pain medications without addressing the underlying nerve compression

Understanding the specific muscles affected by dorsal scapular nerve inflammation is crucial for proper diagnosis and targeted treatment to improve outcomes related to pain, function, and quality of life.