Neurons in the enteric system are derived from neural crest cells originally associated with occipitocervical and sacral regions. It regulates gastrointestinal motility, secretory activity, vascular activity, and inflammation. The first group is the myenteric plexus (also called Auerbach's plexus), which is located between the muscular layers that make up the gastrointestinal system, from the esophagus at the rostral end to the rectum at the caudal end. Additional projections to smaller ganglia are also associated with the pancreas and gallbladder. The submucosa plexus, also called Meissner's plexus, is largely confined to the submucosa of the gut and is most prominent within the small intestine, where it regulates secretory activity and innervates blood vessels. Ref: Waxman S.G. (2010). Chapter 20. The Autonomic Nervous System. In S.G. Waxman (Ed), Clinical Neuroanatomy, 26e.