A 40-year-old man notices drooping of the left shoulder contour and inability to shrug after a radical neck dissection for lymphoma. On examination there is wasting of the trapezius and lateral displacement of the scapula at rest. Which nerve was most likely injured?
- A Long thoracic nerve
- B Spinal accessory nerve ✓
- C Dorsal scapular nerve
- D Supraclavicular nerves
Correct answer: B. Spinal accessory nerve
Explanation
The spinal accessory nerve crosses the posterior triangle of the neck superficially, making it vulnerable during lymph node biopsy and neck dissection. Injury paralyses the trapezius, giving shoulder droop, inability to shrug, lateral scapular displacement, and difficulty in overhead abduction above 90 degrees. Long thoracic nerve injury produces winging on forward push rather than resting scapular displacement, and dorsal scapular injury affects rhomboids, causing mild medial winging without shoulder droop or shrug failure.
Reference: Bailey and Love's Short Practice of Surgery, 28th ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.