Chapter 6 Vagal afferent innervation of the gastrointestinal tract

Abstract

This chapter describes the thoracic and abdominal distribution of the vagi that are available for a number of species. Several points arise from the observations of the gross anatomy of the vagus. First, apart from the stomach and liver, the remaining abdominal viscera (e.g., pancreas) do not receive macroscopically identifiable discrete branches. This means that their afferent innervation can only be studied, by either using tracer techniques or recording afferent activity at a distant site, where the vagus is “contaminated,” by afferents from the other organs. Even in areas of the gut (e.g., small intestine), where discrete nerve bundles can be identified and activity recorded relatively easily, the question of whether they are vagal remains, as the vagal and the splanchnic nerves often share the same terminal course.