Origin of sensation in the esophagus.

The sensory innervation of the esophagus is important both to physicians, for whom esophageal sensation can cause clinical confusion, and to physiologists, who wish to understand the regulation of esophageal motion. Sensory mechanisms in the gut in general are not well understood. Mechanoreceptive reflexes and their pathways, both parasympathetic and sympathetic, have been studied in the esophagus, and thermoreceptive reflex pathways that are parasympathetic have recently been described. The terminal sensory innervation of the esophagus contains several structures that may be receptors to such stimuli. Esophageal striated muscle contains muscle spindles like those of somatic muscle. Within the myenteric plexus, the bodies of certain ganglion cells themselves may be mechanoreceptive. Also, complex subcapsular laminar arborizations that arise from cells of the nodose ganglion have been described in ganglia of the esophageal myenteric plexus. Similar laminar arborizations have been found on vessels of the submucosa in the midesophagus. In the esophageal mucosa, the terminal innervation ends in structures of diverse form located both superficially and deep in the squamous epithelium. Thus, a variety of specific neural structures that seem to represent the terminals of sensory nerves exist in the esophagus and may serve the mechanoreceptive and thermoreceptive reflexes that modify esophageal motility.