Extensive networks of nerve fibres are found in the muscle and mucosa in the
intestine. Most of these fibres arise from ganglion cells in the myenteric or
submucous plexuses, whereas a relatively small proportion arise from extrinsic
ganglia. Although considerable attention has been paid to the innervation
of the external musculature and the control of motility, until the past few
years comparatively little interest has been shown in the distribution and roles
of nerve fibres in the mucosa. A variety of functions may be subserved by
these nerve fibres. Sensory nerve fibres in the mucosa are responsible for
detecting chemical, osmotic and mechanical stimuli, while motor functions
potentially regulated by mucosal nerves include contraction of the muscularis
mucosae, secretions from endocrine and goblet cells, vascular tone, and movement
of water, ions and nutrients across the epithelium. It is also possible that
some nerve fibres have atrophic function.