Severe hyperhidrosis: clinical features and current thoracoscopic surgical management  Fritz J Baumgartner, MD, Youn Toh, MD  The Annals of Thoracic Surgery  Volume 76, Issue 6, Pages 1878-1883 (December 2003) DOI: 10.1016/S0003-4975(03)01069-5

Fig 1 (A) Anatomic relationships between spinal and sympathetic nerves (n.). The sympathetic ganglion communicates with its corresponding spinal nerve through the white (preganglionic) ramus communicans and gray (postganglionic) ramus communicans. Both somatic and sympathetic nervous systems exit and enter the spinal cord via the dorsal (a) and ventral (b) spinal nerve roots. (B) Nerve connections between the central nervous system (CNS) and sympathetic ganglia at the level of T2. Preganglionic, myelinated sympathetic nerves (red) arise in the CNS, enter the ventral spinal nerve and then the white ramus communicans to enter the sympathetic ganglion. The preganglionic nerve may then (a) synapse with postganglionic (efferent, nonmyelinated) sympathetic nerves to reach their effector organs (eg, sweat glands, blood vessels) through ventral and dorsal spinal rami, (b) synapse with postganglionic fibers which pass directly to target viscera (eg, heart), or (c) ascend (or descend) before synapsing. The preganglionic fibers of T2 may ascend higher than T1 and enter the cervical ganglia. Note that one preganglionic fiber (red) may synapse with many postganglionic fibers (black). The sympathetic afferent fibers (blue) enter the CNS via the dorsal spinal nerve root. (C) Schematic view of sympathetic efferent pathways from CNS origin to ganglia to effector organs. Preganglionic fibers (red) may synapse and give off direct postganglionic fibers to target organs (solid black line) or postganglionic fibers reentering spinal nerves (interrupted black lines) via gray ramus communicans and thence to target organs (such as sweat glands). At any given thoracic level, the preganglionic fibers may ascend to higher level(s). The Annals of Thoracic Surgery 2003 76, 1878-1883DOI: (10.1016/S0003-4975(03)01069-5)