This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Central Neuraxial Blockade, Subject name: Anaesthesia
The site of action of local anaesthetic in epidural anesthesia is 
Select and explain. 
A. Spinal nerve root, B. Spinal cord, C. Epidural neural tissue, D. Anterior root of spinal nerve
A: Spinal nerve root
Answer: A: Spinal nerve root 
Explanation: Local anaesthetic in maximal blockade is believed to act in spinal nerve root. Mechanism of action of central neuraxial blockade. The mechanisms of spinal and epidural are believed to be the nerve roots. Blockade of neural transmission in the posterior nerve root fibers interrupt somatic and visceral sensation, whereas blockade of anterior nerve root fibers prevent efferent motor & autonomic outflow.