What is the Myenteric Plexus?

The myenteric plexus is a network of nerve fibers located within the layer of muscular tissue that lines the esophagus, stomach, and intestines. It is part of the enteric nervous system, a subdivision of the peripheral nervous system that is responsible for controlling the activities of the digestive tract. This particular structure mediates the contractions of the muscular layer, key to moving food through the body so that it can be processed by the metabolism.

This structure is sometimes regarded as part of the autonomic nervous system. It does act primarily below the level of consciousness, automatically sending signals to the gastrointestinal tract on the basis of trigger events. It acts autonomously and in concert with a number of other systems to enable the digestion and metabolism of food. However, the central nervous system can also be involved with conscious control of the myenteric plexus if it becomes necessary.

Also known as Auerbach's plexus after the first anatomist to describe it, the myenteric plexus innervates the mucosal lining of the digestive tract and is primarily responsible for intestinal motility. Motility disorders, where the gastrointestinal tract does not contract and relax normally, sometimes involve damage to the nerve fibers in the myenteric plexus. Achalasia is an example of a disorder that can involve this structure.

Within the network of nerve fibers that makes up the myenteric plexus, there are a number of outlying clusters of nerve ganglia that control individual areas of the intestine. Although they are sometimes taken to be in isolation, they are all part of an interconnected system and everyone has just one myenteric plexus, not many individual structures. Together, the nerve fibers and ganglia provide the primary source of innervation to the intestinal tract and there are more cells in this structure than there are in the spinal cord.

When patients develop motility disorders that interfere with eating, digestion, and metabolism, a number of screening tests including imaging studies can be performed to learn more about the origins of the disorders and to pinpoint the location or locations in the intestinal tract where the muscular lining is not moving as it should be. These tests can include an assessment to determine if nerve fibers or ganglia in the myenteric plexus have been damaged. These cells can be seen on biopsies of the lining of the intestinal tract taken during a surgical biopsy and reviewed by a pathologist.