This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Nerve Injuries - 1, Subject name: Orthopaedics
Brachial plexus injury with Horner's syndrome, nerve root level involved is : 
Select and explain. 
A. C5, B. C6, C. C7, D. T1
D: T1
Answer: D: T1 
Explanation: - Horner syndrome is due to involvement of white matter of spinal cord at T1 level." Klumpke's palsy: Occurs in lower trunk of brachial plexus (C8-T1) Claw hand is present due to the paralysis of intrinsic muscles of hand It is associated with Horner's syndrome Has poor prognosis