Injury to which part of the brachial plexus is responsible for Klumpke's palsy, and which root(s) are involved?
- A Upper trunk (C5, C6) — causes waiter's tip position
- B Lower trunk (C8, T1) — causes claw hand and Horner syndrome if T1 rami communicantes are involved ✓
- C Posterior cord (C5–C8) — causes wrist drop and deltoid weakness
- D Medial cord (C8, T1) only — causes isolated thenar wasting
Correct answer: B. Lower trunk (C8, T1) — causes claw hand and Horner syndrome if T1 rami communicantes are involved
Explanation
Klumpke's palsy results from traction injury to the lower trunk (C8, T1) of the brachial plexus, typically from excessive arm abduction or breech delivery. It causes intrinsic hand muscle paralysis (interossei, hypothenar, medial lumbricals) producing claw hand, and sensory loss over the medial forearm and hand. If the T1 white rami communicantes are damaged, Horner syndrome (ptosis, miosis, anhidrosis) occurs ipsilaterally. Upper trunk (C5, C6) injury causes Erb's palsy (waiter's tip deformity).
Reference: BD Chaurasia's Human Anatomy, 8th ed.
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Written and medically reviewed by the StethoPrep medical team.