The long thoracic nerve (nerve of Bell) arises from C5, C6, C7 roots and innervates serratus anterior. Injury to this nerve during radical mastectomy or thoracotomy produces:

• A Winging of scapula medially, accentuated when pushing against a wall ✓
• B Winging of scapula laterally, accentuated when lifting the arm
• C Loss of shoulder abduction above 90°
• D Loss of medial rotation and adduction of the shoulder

Explanation

Serratus anterior holds the medial border of the scapula against the thoracic wall and rotates the scapula upward during arm elevation. Long thoracic nerve palsy causes medial winging — the medial border of the scapula protrudes away from the thoracic wall, most evident when the patient pushes against a wall or performs a push-up (serratus anterior is most active during protraction of the scapula). Lateral winging (where the lower angle moves laterally) is caused by trapezius weakness (accessory nerve palsy), accentuated with arm elevation.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.