Functional properties of spinal visceral afferents supplying abdominal and pelvic organs, with special emphasis on visceral nociception

TLDR: The functional and the morphological properties of the spinal visceral afferent neurons, supplying the abdominal and pelvic organs, are discussed, including special emphasis has been placed on the visceral nociception and pain.

Abstract: Publisher Summary This chapter discusses the functional and the morphological properties of the spinal visceral afferent neurons, supplying the abdominal and pelvic organs. These neurons are involved in the regulation of the visceral functions, in sensations and in various spinal and supraspinal reflexes. Special emphasis has been placed on the visceral nociception and pain. The spatial resolution of the sensations that can be elicited from the viscera is relatively vague and can be fully explained, by the segmental width of the afferent inflow from each viscus. Most spinal visceral afferent units have various common functional properties: they are silent or display a low rate of ongoing activity; their axons are unmyelinated or thinly myelinated (conduction velocity below 2 m/second and mostly below 20 m/second, respectively); their receptive fields consist of from 1-9 mechanosensitive sites located in the mesenteries on the serosal surface or on the walls of the organs; local pressure in their receptive fields elicits slowly adapting responses; they respond to distensions and contractions of the viscera and to stretching of their mechanosensitive endings; they respond to various chemical stimuli applied in their receptive fields.