Figure 1.

Peripheral tissues including skin, stomach, pancreas and prostate are innervated by sensory neurons of the dorsal root ganglia (DRG; solid black lines). Thoracic and abdominal organs also receive sensory input from primary afferents whose cells bodies are located in the nodose ganglion (NG; solid red lines) and travel in the vagus nerve (VN). Sensory innervation from DRG to the stomach and pancreas travels with sympathetic preganglionic axons (right side of diagram) in the greater splanchnic nerve (SN) and pass through the celiac ganglion (CG) before reaching their target organ. The VN also contains parasympathetic preganglionic axons (dashed red lines) whose cell bodies are located in the brainstem. These axons synapse on parasympathetic postganglionic neurons (not shown) in the organ wall. Sympathetic innervation arises from sympathetic preganglionic neurons (blue dashed lines, right side of diagram) whose cell bodies are in the spinal cord at T1-L2 vertebral levels. Axons from these neurons innervate sympathetic postganglionic neurons in paravertebral ganglia (PG) located alongside the vertebral column or prevertebral ganglia found near the organ. Prevertebral ganglia include the CG, that innervates the stomach and pancreas, and the inferior mesenteric ganglion (IMG) that innervates the prostate. Preganglionic parasympathetic axons innervating the prostate (dashed red lines) arise from neurons located at sacral spinal cord levels and travel via pelvic SN to synapse on postganglionic parasympathetic neurons near the base of the bladder (not shown). Skin receives both sensory and sympathetic postganglionic input from appropriate spinal levels, but no parasympathetic input.