A motorcyclist suffers a forceful lateral flexion injury of the neck to the right. Examination shows loss of shoulder abduction, elbow flexion, and lateral forearm sensation on the right. The paralysed muscles are in a position of medial rotation and adduction — the 'waiter's tip' posture. Which roots are involved?

• A C5, C6 ✓
• B C8, T1
• C C6, C7
• D C5, C6, C7

Explanation

Erb-Duchenne palsy involves C5 and C6 roots (upper trunk of brachial plexus). Muscles affected include deltoid (C5,6 — shoulder abduction lost), biceps (C5,6 — elbow flexion lost), brachialis, brachioradialis, and supinator. The arm hangs medially rotated and adducted, producing the 'waiter's tip' or 'porter's tip' deformity. Lateral forearm skin (from lateral cutaneous nerve of forearm — musculocutaneous C5,6) is anaesthetic. C8-T1 involvement produces Klumpke palsy with 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.