Scapular Winging: Long Thoracic vs Spinal Accessory Nerve
Nerve Injuries · 6 min read · 2025-12-20
Introduction
Scapular winging — protrusion of the scapula from the posterior chest wall — has two primary neurogenic causes. The pattern of winging immediately identifies which nerve is affected, guiding further evaluation and management.
Medial Winging: Long Thoracic Nerve (Serratus Anterior)
The long thoracic nerve (C5–C7) innervates serratus anterior, which holds the medial border of the scapula against the thoracic wall and protracts the scapula.
Cause: Traction injuries, viral neuritis (Parsonage-Turner syndrome), surgical damage (axillary lymph node dissection, thoracotomy), repetitive overhead activity.
Clinical pattern:
- The medial border of the scapula wings posteriorly
- Winging is most prominent with forward flexion or pushing against a wall
- The scapula lifts off medially
- Weakness of protraction — difficulty punching forward
- Overhead reach is impaired because the scapula cannot rotate upward normally
Test: Wall push-up — medial border protrudes dramatically.
Lateral Winging: Spinal Accessory Nerve (Trapezius)
The spinal accessory nerve (CN XI) innervates trapezius (and SCM). Injury produces loss of the middle and lower trapezius function.
Cause: Surgical damage in the posterior triangle of the neck (lymph node biopsy — the most common iatrogenic nerve injury in the neck), trauma, tumors.
Clinical pattern:
- The scapula displaces laterally and downward
- Winging is most prominent with arm abduction (not forward flexion)
- Shoulder droop — the shoulder sits lower on the affected side
- Weakness of shoulder shrug (upper trapezius) and scapular retraction (middle trapezius)
Test: Ask the patient to abduct the arm to 90° — the scapula shifts laterally.
Quick Differentiation
Clinical Pearl
If you are unsure whether winging is present, observe the patient from behind while they slowly forward flex both arms and then abduct both arms. Compare the scapulae side to side. Subtle winging that is invisible at rest becomes obvious during these loaded movements.
Summary
Wall push-up reveals serratus anterior winging (medial border lifts). Arm abduction reveals trapezius winging (scapula shifts laterally). The direction of displacement and the provoking movement tell you the nerve — no further testing needed.