A patient undergoes left axillary lymph node dissection for breast carcinoma and subsequently develops winging of the left scapula that is WORSENED by pushing against a wall. The injured nerve and its origin are:

• A Spinal accessory nerve (CN XI) — injury to trapezius
• B Dorsal scapular nerve (C5) — injury to rhomboids
• C Thoracodorsal nerve (C6, C7, C8) — injury to latissimus dorsi
• D Long thoracic nerve (C5, C6, C7) — injury to serratus anterior ✓

Explanation

The long thoracic nerve (nerve of Bell, C5–C7) runs superficially along the lateral chest wall and is vulnerable during axillary dissection. It supplies serratus anterior, which holds the medial border of the scapula against the thoracic cage; its denervation produces medial winging that is exaggerated by forward pushing (protracting the arm against resistance). Trapezius winging (CN XI injury) is lateral and worsened by arm elevation, not forward pushing. Rhomboid or latissimus dorsi loss does not produce classic wall-push winging.

Reference: BD Chaurasia's Human Anatomy, 8th ed.

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Written and medically reviewed by the StethoPrep medical team.