The distribution of spinal and vagal sensory neurons that innervate the esophagus of the cat.

The distribution of spinal and vagal neurons that convey sensory information from the distal smooth muscle esophagus is poorly documented. Therefore, sensory cell bodies were retrogradely labeled by injecting fast blue into the striated and smooth muscle of the esophageal body and into the lower esophageal sphincter of the cat. The maximum distribution of spinal sensory neuron labeling was found in the following dorsal root ganglia: C1-T8 (striated muscle); C5-L2 (smooth muscle), and T1-L3 (lower esophageal sphincter). Vagal sensory neurons in the nodose ganglion were found to have a crude topographic layout. The total number of vagal sensory neurons labeled by injection into the three esophageal areas was greater than the number of spinal neurons labeled (809.7 +/- 166.1 vs. 328.9 +/- 53.4; mean +/- SEM; n = 12; P less than 0.005). It is concluded that spinal sensory neurons of the esophagus are segmentally arranged. Accordingly, each level of the esophagus has a distinct but overlapping sensory projection to the spinal cord, and afferents from all parts of the esophagus overlap the known spinal distribution of cardiac afferents.