The innervation of the liver

According to recent studies, the innervation of the gastrointestinal organs, including the large digestive glands, appears to be organized in a rather hierarchical system1,2 of which, however, not many details are well known. Similarly, the liver exhibits a so-called intrinsic nervous system, which is built up by neurones located within the hilus region of this organ. These neurones of the liver are found associated with the hepatic nerve plexus at the hilus surrounding the entering blood vessels, mainly the hepatic arteries. The hepatic nerves of sympathetic or parasympathetic origin may modulate the activity of the intrinsic liver nerves, and, probably, important local circuits may be formed by the intrinsic ganglia and their intraparenchymatous fibres. The nerves within the liver may also stem directly from sympathetic or vagal connections3–8, then constituting the so-called extrinsic liver innervation. They belong to the primary liver nerves running with the vagus nerve or the thoracic sympathetic branches: these nerves are mainly afferent and possibly efferent in nature. This concept of liver innervation can be postulated from a number of review publications9-11.