Читать книгу The Esophagus - Группа авторов - Страница 114

The structure of the SPG consists of sensory input into a programming circuitry of neurons and a group of appropriate motor neurons [7]. There are two groups of neurons with specific functions in the programming circuitry (Figure 5.1): (i) the dorsal swallowing group (DSG), located in the nucleus of the solitary tract (NTS) and adjacent dorsal medullary reticular formation, responsible for generation and timing of swallow related events; and (ii) a ventral swallowing group (VSG), a collection of interneurons within the ventral reticular formation dorsomedial to the nucleus ambiguus, which function as a switching station for signals from the DSG to motor neurons of cranial nerves innervating muscles in the swallowing pathway [2]. Input from higher centers such as the cortex feed into each stage of the SPG. Bilateral connectivity occurs at the level of the NTS; additionally, the DSG and VSG are connected either directly or through interneurons. Sensory feedback from the periphery modulates the activity of the programming circuitry.

Figure 5.1 Central control of the oropharynx and esophagus. The oropharyngeal circuitry is shown on the left and the esophageal on the right. Both have a dorsal swallowing group (DSG) in the solitary tract nucleus for programming and organizing the sequential events in their respective locations. The oropharyngeal DSG leads the esophageal DSG. The oropharyngeal mechanism has a ventral swallowing group (VSG) in the ventral lateral medulla where “switching” of the DSG signaling distributes excitation to the appropriate cranial nerves for the mouth, pharynx, and larynx. The esophageal circuit likely has a VSG but may be simpler, with a direct connection from the DSG to the motor nuclei. Both circuits can receive inputs from the periphery, the cerebral cortex, and various supramedullary structures. DMX, dorsal motor nucleus of the vagus; NA, nucleus ambiguus.

Source: Jean [7] with permissions of Springer Nature.