As you can see in the diagram, the stellate ganglion is a little bundle of nerves in your neck adjacent to the vertebrae. It's part of a system of nerves running along your entire spine that function to regulate heart rate, blood pressure, perspiration, digestive activities, and more. It's widely known as the "fight or flight" system. When you feel a cold chill go up your spine, or your heartbeat quickens in response to fright, that's your sympathetic chain in action.

Here is what we see when we put an ultrasound transducer on a patient's neck in preparation for a stellate block. You're looking down from the skin into the body. The green arrow shows the needle path toward the yellow line, which identifies the soft tissue layer where the medication must go. It's adjacent to your C6 vertebral bone, and next to the carotid artery (CA), and jugular vein (IJV).