In a Klumpke's palsy (C8, T1 avulsion), which specific deformity is seen and why?

• A Claw hand affecting all four fingers due to loss of all intrinsic hand muscles and unopposed long flexors ✓
• B Claw hand affecting only the ring and little fingers due to loss of ulnar intrinsics with intact median intrinsics
• C Wrist drop due to radial nerve involvement at C8 level
• D Ape thumb deformity due to selective thenar muscle paralysis

Explanation

Klumpke's palsy involves C8 and T1 roots. At these levels, both the ulnar nerve (C8, T1) and median nerve's intrinsic motor component (C8, T1 via anterior interosseous and recurrent motor branch) are affected, paralysing all intrinsic hand muscles including all lumbricals and interossei. With all intrinsics paralysed and long flexors intact, all four fingers develop clawing (hyperextension at MCPs, flexion at IPs). Additionally, if T1 root is avulsed, Horner's syndrome occurs due to damage to the sympathetic fibers traveling through T1. The classic Erb's palsy claw affects only ring and little fingers.

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

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Written and medically reviewed by the StethoPrep medical team.