A 25-year-old motorcyclist sustains a high-velocity road accident. He has loss of shoulder abduction, elbow flexion, and wrist extension but intact hand intrinsics and finger flexion. This pattern is consistent with injury to which roots of the brachial plexus?

• A C5–C6 roots (Upper trunk — Erb's palsy pattern) ✓
• B C7–C8–T1 roots (Lower trunk — Klumpke's palsy pattern)
• C C5–C6–C7 roots (Upper and middle trunk injury)
• D T1 root only

Explanation

C5–C6 root injury produces Erb's palsy: loss of shoulder abduction (deltoid, supraspinatus — C5), shoulder external rotation, elbow flexion (biceps — C5/6) and wrist extension (C6), with preservation of hand function (C8/T1 intact). The classic posture is the 'waiter's tip' position — arm adducted, internally rotated, elbow extended, forearm pronated. C7–C8–T1 injury (Klumpke's palsy) results in intrinsic hand weakness/claw hand. The question scenario is a pure upper trunk (C5–C6) injury without C7 involvement, so wrist extension is affected but finger extension (C7) should be tested; the preserved hand intrinsics confirm C8/T1 sparing.

Reference: Maheshwari Essential Orthopaedics, 6th ed.

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Written and medically reviewed by the StethoPrep medical team.