This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Peripheral Nerve Injuries, Subject name: Orthopaedics
Brachial plexus injury with horners syndrome, nerve root level involved is - 
Select and explain. 
A. C5, B. C6, C. C7, D. T1
D: T1
Answer: D: T1 
Explanation: Ans. is 'd' i.e., T1 Horner's syndrome* It is seen in patients with brachial plexus injury with lesion at T1 root level.* In it T1 root is injured proximal to white ramus communicans to first thoracic sympathetic ganglion.* Patient presents with ptosis, miosis, anhydrosis, enophthalmos, and loss of ciliospinal reflex-may be associated.* Loss of ciliospinal reflex is seen as sympathetic fibres to the head and neck leave the spinal cord through nerve T1.