A construction worker sustains an injury with hyperabduction of the arm over a prolonged period. He presents with weak shoulder abduction and elbow flexion but preserved forearm and hand movements. Sensory loss is over the lateral forearm. Which nerve roots and trunk are injured?

• A C5, C6 — upper trunk (Erb-Duchenne) ✓
• B C8, T1 — lower trunk (Klumpke's)
• C C7 — middle trunk
• D C5, C6, C7 — all three trunks

Explanation

This describes an upper trunk brachial plexus injury (Erb-Duchenne palsy) involving C5 and C6 roots. The classic posture is 'waiter's tip' — shoulder adducted, internally rotated; elbow extended; forearm pronated. Weakness of deltoid (C5), supraspinatus/infraspinatus, biceps (C5, C6), and brachioradialis occurs. Sensory loss is over the lateral arm and forearm (C5, C6 distribution). Klumpke's palsy involves C8-T1, causing intrinsic hand muscle weakness and claw hand.

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

High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP

Written and medically reviewed by the StethoPrep medical team.