The coeliac ganglion is a paired ganglion of the sympathetic nervous system and is located anterior to the spine at the level of the twelfth thoracic vertebra at the branch of the coeliac trunk from the aorta, the main body artery. Beyond the efferent sympathetic nerve fibers, the ganglion is also interconnected with afferent visceral fibers so that it receives feedback from the intestine and other organs of the abdominal cavity. The coeliac ganglion functions as the first control center for the digestive system.
What is the coeliac ganglion?
The paired ganglia coeliaca, also known as the abdominal coeliac ganglia, are among the prevertebral ganglia located in the abdominal cavity anterior to the spine. They form the largest collection of nerve ganglia within the prevertebral sympathetic ganglia and lie on either side of the branch of the main abdominal artery from the descending aorta. The branch from the aorta is called the truncus coeliacus. Secondary neurons of the ganglia coeliaca surround the truncus coeliacus in a braided fashion and together form the coeliac plexus. Together with the ganglion mesentericum superius, which is also composed of sympathetic fibers, the solar plexus is formed, also known as the solar plexus or solar plexus. The sympathetic nerve fibers that travel to the coeliac sinistra ganglion and the dextra ganglion are composed primarily of axons from cell bodies of the spinal cord at the level of the lower thoracic and upper lumbar vertebrae. These are mainly two presynaptic or preganglionic sympathetic nerve cords, the splanchnic nerve major and the splanchnic nerve minor. Preganglionic nerve fibers conduct primary neuronal signals, which have not yet undergone any amplification, attenuation, or other processing by ganglia or synapses, to the ganglia. Only here is there initial “processing” of the signals and switching to secondary or postganglionic neurons, which leave the ganglia as efferents and conduct the processed signals to target organs or to further processing centers in the PNS or CNS.
Anatomy and structure
The two ganglia coeliaca are part of the enteric nervous system (ENS), also known as the visceral nervous system or abdominal brain, which has gained enormous popularity and attention in recent years. Since the ganglia are also part of the sympathetic nervous system, mainly efferent sympathetic nerve cords enter the ganglia coeliaca via the two nervi splanchnici. The cell bodies of the nervi planchnici are located in the spinal cord, and their preganglionic axons are surrounded by medullary sheaths. The postganglionic efferent nerve fibers originating from both ganglia coeliaca are marrowless and conduct information or action potentials to target organs or target tissues. However, the ganglia coeliaca also require status messages from the target organs to do their work, so afferent nerve fibers also travel to the ganglia. Through afferent fibers, the ganglia receive real-time information from target tissues and target organs. In addition, parasympathetic fibers also draw into the ganglia coeliaca. Numerous postganglionic branches and connections to abdominal organs arise from the ganglia, which are supplied and controlled by the coeliac plexus and other subordinate plexuses.
Function and Tasks
As part of the autonomic nervous system, the paired ganglia coeliaca, which together form the coeliac plexus, perform important functions in the autonomic control of certain abdominal organs. In detail, these are the stomach, liver, spleen, pancreas and kidneys as well as the intestinal section from the stomach up to and including the transverse part of the large intestine (colon) and testes or ovaries. The abdominal ganglia or coeliac plexus are supported by numerous downstream nerve plexuses with which they are directly interconnected. Direct connections exist, for example, to the renal plexus, gastric plexus, hepatic plexus, pancreatic plexus and several others. The vegetative control of the organs, which is usually not consciously perceived, takes place via visceromotor fibers belonging to the sympathetic nervous system. Action potentials control the release of secretions from the corresponding organs and their movement, such as peristalsis of the intestine or contractions of the pancreas or gallbladder.The smooth muscles in the walls of certain arterial vessels are also vegetatively adjusted in tone to meet requirements. During acute stress phases, the tiny muscles in the vessel walls are stimulated to contract, so that the cross-section of the vessels narrows and blood pressure rises. Because autonomic control of some organs depends on feedback from the organs, sensitive afferents from the organs also come into direct contact with the ganglia coeliaca.
Diseases
To carry out autonomic control of the abdominal organs without interference, the ganglia coeliaca require feedback or status messages from the organs and information about the level of sympathetic tone, the state of excitation of the sympathetic nervous system. In cases of dysfunction of the abdominal ganglia, the causes may lie in the nerve ganglia themselves or in the afferent sensory nerve fibers originating from the organs. Similarly, axons of higher-level centers in the CNS, which pass through the nervi splanchnici into the ganglia coeliaca, may be disrupted. The complexity of the circuitry of superior and inferior nerve nodes make it possible that dysfunction in the abdominal ganglia can be partially compensated by other nerve nodes. The effects of a complete failure of the ganglia coeliaca can be gauged from the blockade of the abdominal ganglia artificially produced for therapeutic purposes. Such a blockade is mainly used for pain reduction in palliative medicine, for example to relieve pain in pancreatic cancer. The action potentials of the pain receptors (nociceptors) of the abdominal organs then remain ineffective. Side effects of blockade of the ganglia coeliaca may include diarrhea, neuritis, and a drop in blood pressure.
