Brainstem control of deglutition: Brainstem neural circuits and mediators regulating swallowing

Abstract

Swallowing requires coordination of several paired muscle groups in the head and neck including the diaphragm. Thus, motoneurons of the Vth, VIIth, IX through XIIth cranial, cervical spinal, and phrenic nerves are sequentially activated by a swallowing pattern generator (SPG) located in the lower brainstem for executing the oral, pharyngeal, and esophageal stages of swallowing. Independence of these stages from each other indicates distinct subcircuits, their coupling pointing to flexible links between them. Although intrinsically autonomous, the SPG depends on peripheral and suprabulbar afferents for proper functioning. Pivotal to both, integrating afferents and coordinating stage-specific subcircuits, are the nucleus tractus solitarii (NTS) with some of its subnuclei and their reciprocal interconnections with the brainstem reticular formation. This chapter provides a survey of the anatomical and functional organization of the SPG.