The innervation of the intestines is very complex, and it comes from the intrinsic and extrinsic neurons forming intrinsic and extrinsic nervous systems, respectively. The intrinsic nervous system is located and formed within the intestines. It is interwoven in the wall of the intestines and includes the enteric nervous system consisting of two nerve plexuses that provide local, autonomous functions. However, the intrinsic system also receives input from the extrinsic nervous system.