A newborn has the right arm held in adduction, medial rotation, and pronation with loss of flexion at the elbow and absence of the Moro reflex on the right side. Grip reflex is present. This is Erb-Duchenne palsy. The avulsed roots are:

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

Explanation

Erb-Duchenne palsy results from traction injury to the C5 and C6 roots or the upper trunk of the brachial plexus (at Erb's point — the junction of C5 and C6 anterior to scalenus anterior). Paralysis of shoulder abductors (C5), external rotators, elbow flexors (C5, C6), and supinators produces the 'waiter's tip' posture (arm adducted, medially rotated, elbow extended, forearm pronated). Grip reflex (C8, T1) is preserved. C8–T1 injury causes Klumpke's palsy with intrinsic hand weakness and claw hand. C5–C7 palsy adds additional elbow and wrist flexion weakness.

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

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Written and medically reviewed by the StethoPrep medical team.