The hepatic plexus is a sympathetic and

parasympathetic The parasympathetic nervous system (PSNS) is one of the three divisions of the autonomic nervous system, the others being the sympathetic nervous system and the enteric nervous system. The autonomic nervous system is responsible for regulat ...

nerve plexus A nerve plexus is a plexus (branching network) of intersecting nerves. A nerve plexus is composed of afferent and efferent fibers that arise from the merging of the anterior rami of spinal nerves and blood vessels. There are five spinal nerve ple ...

that provides innervation to the

parenchyma upright=1.6, Lung parenchyma showing damage due to large subpleural bullae. Parenchyma () is the bulk of functional substance in an animal organ such as the brain or lungs, or a structure such as a tumour. In zoology, it is the tissue that ...

of the liver as well as contributing innervation to some other abdominal structures. Its sympathetic component is derived from the coeliac and superior mesenteric plexuses; its parasympathetic component is derived from the

anterior Standard anatomical terms of location are used to describe unambiguously the anatomy of humans and other animals. The terms, typically derived from Latin or Greek roots, describe something in its standard anatomical position. This position pro ...

and posterior vagal trunks.

Anatomy

Afferents

Sympathetic

The plexus receives post-ganglionic sympathetic afferents from the

celiac plexus The celiac plexus, also known as the solar plexus because of its radiating nerve fibers, is a nerve plexus, complex network of nerves located in the abdomen, near where the celiac trunk, superior mesenteric artery, and renal arteries branch fro ...

, and the

superior mesenteric plexus The superior mesenteric plexus is a continuation of the lower part of the celiac plexus, receiving a branch from the junction of the right vagus nerve with the plexus. It surrounds the superior mesenteric artery, accompanies it into the mesentery, ...

. The hepatic plexus is the largest derivative of the celiac plexus.

Parasympathetic

The plexus receives pre-ganglionic parasymathetic afferents primarily from the anterior vagal trunk, with a lesser contribution from the posterior vagal trunk. The anterior vagal trunk issues one or more hepatic branches of anterior vagal trunk that pass in the superior portion of the

lesser omentum The lesser omentum (small omentum or gastrohepatic omentum) is the double layer of peritoneum that extends from the liver to the lesser curvature of the stomach, and to the first part of the duodenum. The lesser omentum is usually divided into t ...

to reach the hepatic plexus.

Efferents and distribution

The plexus is the primary source of innervation for the

of the liver. Efferents of the plexus accompany the branches of the

portal triad In histology (microscopic anatomy), the lobules of liver, or hepatic lobules, are small divisions of the liver defined at the microscopic scale. The hepatic lobule is a building block of the liver tissue, consisting of portal triads, hepatocytes ...

through the

porta hepatis The porta hepatis or transverse fissure of the liver is a short but deep fissure, about 5 cm long, extending transversely beneath the left portion of the right lobe of the liver, nearer its posterior surface than its anterior border. It join ...

into the liver, ultimately reaching as far as the individual

hepatocytes A hepatocyte is a cell of the main parenchymal tissue of the liver. Hepatocytes make up 80% of the liver's mass. These cells are involved in: * Protein synthesis * Protein storage * Transformation of carbohydrates * Synthesis of cholesterol, bile ...

. Multiple fine branches arise from the plexus to be distributed to the

gallbladder In vertebrates, the gallbladder, also known as the cholecyst, is a small hollow Organ (anatomy), organ where bile is stored and concentrated before it is released into the small intestine. In humans, the pear-shaped gallbladder lies beneath t ...

, and the extrahepatic

bile ducts A bile duct is any of a number of long tube-like structures that carry bile, and is present in most vertebrates. The bile duct is separated into three main parts: the fundus (superior), the body (middle), and the neck (inferior). Bile is requ ...

. Some accompany the gastroomental artery to provide a minor contribution to the innervation of the stomach. Some efferents from the plexus accompany the

right gastric artery The right gastric artery usually arises from the proper hepatic artery. It descends to the pyloric end of the stomach The stomach is a muscular, hollow organ in the upper gastrointestinal tract of Human, humans and many other animals, includ ...

to reach and contribute to the innervation of the

pylorus The pylorus ( or ) connects the stomach to the duodenum. The pylorus is considered as having two parts, the ''pyloric antrum'' (opening to the body of the stomach) and the ''pyloric canal'' (opening to the duodenum). The ''pyloric canal'' ends a ...

. Some accompany the

gastroduodenal artery In anatomy, the gastroduodenal artery is a small blood vessel in the abdomen. It supplies blood directly to the pylorus (distal part of the stomach) and proximal part of the duodenum. It also indirectly supplies the pancreatic head (via the anterio ...

and its branches to reach the pylorus, proximal duodenum, and the pancreas.

Physiology

Hepatic

Other than their role in mediating

vasoconstriction Vasoconstriction is the narrowing of the blood vessels resulting from contraction of the muscular wall of the vessels, in particular the large arteries and small arterioles. The process is the opposite of vasodilation, the widening of blood vesse ...

, the function of the plexus' efferents is unclear. Efferents are apparently involved in regulating hepatic metabolism, and sinusoidal blood flow control. The plexus is however not functionally essential, as demonstrated by the continued functioning of transplanted livers where the efferents of the plexus are cut during the transplantation process. Efferents to the liver are involved in

cholinergic Cholinergic agents are compounds which mimic the action of acetylcholine and/or butyrylcholine. In general, the word " choline" describes the various quaternary ammonium salts containing the ''N'',''N'',''N''-trimethylethanolammonium cation ...

, aminergic,

peptidergic Peptides are short chains of amino acids linked by peptide bonds. A polypeptide is a longer, continuous, unbranched peptide chain. Polypeptides that have a molecular mass of 10,000 Da or more are called proteins. Chains of fewer than twenty ami ...

, and nitrergic

neurotransmission Neurotransmission (Latin: ''transmissio'' "passage, crossing" from ''transmittere'' "send, let through") is the process by which signaling molecules called neurotransmitters are released by the axon terminal of a neuron (the presynaptic neuron ...

Biliary

The parasympathetic component of the plexus' efferents to the gallbladder and extrahepatic bile duct is visceral motor and innervates the smooth muscle in the walls of the ducts and gallbladder.

References

External links

* {{Authority control Nerve plexus Nerves of the torso Vagus nerve