Motor control of the stomach

The complex repertoire of gastric motor function is controlled and coordinated by reflexes that match gastric tone and peristaltic activity to the digestive needs of the individual. These reflexes operate both at the level of the enteric nervous system and through autonomic connections to the brain and spinal cord, with excitatory and inhibitory enteric motor neurones providing the final pathway for both intrinsic and extrinsic reflexes. The electrophysiological properties, neurochemical coding and projection patterns of these enteric neurones have been well characterised enabling the detailed circuit diagrams for contraction and relaxation of the corpus and antrum to be described. Extrinsic influences, from the vagus and splanchnic nerves, have a widespread action on enteric neural transmission, despite the relative paucity of extrinsic to intrinsic neurones. The stomach has a rich sensory innervation and the properties of vagal and spinal afferents have been well characterised. In contrast, the nature of the intrinsic primary afferent neurone has not been resolved despite abundant functional data for their existence. A concept for permissive control is presented, whereby autonomic inputs to enteric circuits set the “gain” for enteric reflexes. Plasticity in these circuits accounts for the adaptation of gastric function that occurs when the extrinsic innervations is compromised by surgery or disease.