The autonomic nervous system (ANS) regulates involuntary functions and is divided into the sympathetic and parasympathetic divisions. The sympathetic division, also called the thoracolumbar outflow, supplies smooth muscles, blood vessels, heart, lungs, glands, and gastrointestinal organs. It consists of preganglionic and postganglionic fibers and is arranged in three ganglia groups: paravertebral/sympathetic chain ganglia, prevertebral/collateral ganglia, and terminal/peripheral ganglia. The sympathetic chain ganglia are arranged segmentally along the vertebral column and are divided into cervical, thoracic, lumbar, and sacral ganglia. Preganglionic fibers originate in the