Long thoracic nerve injury

1. Where do the long thoracic nerve fibers originate?
2. What muscle does the long thoracic nerve innervate?
3. What is the difference between scapular winging caused by long thoracic nerve vs. spinal accessory nerve injury?
4. What are common causes of long thoracic nerve injury?

Answers:
1. C5, C6, C7 roots.
2. Serratus anterior.
3. Long thoracic nerve injury causes serratus anterior weakness, resulting in winging that brings the scapula more medial, and winging is decreased by abduction. Spinal accessory nerve injury causes trapezius weakness, resulting in winging that brings the scapula away from the midline, and is increased by abduction.
4. Fall, MVA, sports injury, shoulder bags.