Ingy Iskander MD
Assistant Instructor 
UT Southwestern Medical Center and Children's Medical Center

You have been asked to perform a stellate ganglion block on a 17-year-old male with complex regional pain syndrome.  To avoid radiation exposure and in order to visualize the neurovascular anatomy you decide to perform the block under ultrasound guidance.  Below is the image you obtain:

Which letter represent the best location for local anesthetic deposition: