Figure 5 - Diagram of the oropharyngeal and esophageal circuits.

The oropharyngeal circuit includes two main groups of brainstem neurons: a dorsal swallowing group (DSG) located within the NTS, and a ventral swallowing group (VSG) located in the ventrolateral medulla. The DSG contains the generator neurons involved in triggering, shaping, and timing the sequential or rhythmic swallowing pattern. The VSG contains the switching neurons, which distribute the swallowing drive to the various pools of motoneurons involved in swallowing. The esophageal circuit may involve a DSG, a VSG, and the motor or preganglionic nuclei. However, the circuit may be simpler, with a direct connection between the DSG and motor nuclei. Both circuits may receive information from the periphery, from the cerebral cortex, and from various supramedullary structures. DMX, dorsal motor nucleus of the vagus, NA, nucleus ambiguus.