This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: Anaesthesia of special situations, Subject name: Anaesthesia
In Phrenic nerve block, it is best to infiltrate near 
Select and explain. 
A. Scalenus anterior, B. Scalenus posterior, C. Posterior border of sternomastoid, D. Anterior border of sternomastoid
C: Posterior border of sternomastoid
Answer: C: Posterior border of sternomastoid 
Explanation: Phrenic nerve is blocked 3 cm above the clavicle at the posterior border of sternomastoid. Used for intractable hiccups