The sympathetic nervous system is a series of nerves that spread from your spine to your body. These nerves help control several body functions that you have no control over, called involuntary body functions. Blood flow, digestion, and sweating are some of these functions. Sympathetic blocks can target a range of nerves, including the Stellate Ganglion (in front of the 6th-7th cervical vertebrae), Celiac Plexus (abdomen), Lumbar Sympathetic Chain, Superior Hypogastric Plexus, and Ganglion Impar.