ABSTRACT
The gastrointestinal (GI) tract and accessory organs (e.g., liver and biliary tree) have a rich sensory innervation (1). Sensory afferents from the digestive tract project to the central nervous system (CNS) in the vagus and spinal sensory nerves. However, some enteric reflexes (e.g., mucosal stroking) are retained after connections to the CNS are severed indicating that the neural network of the enteric nervous system (ENS) contains the elements necessary for assimilation of information and coordinated motor output (2). These intrinsic sensory neurons in the enteric neural networks do not project to the CNS and therefore are not believed to contribute to gut sensations per se. This chapter will focus on extrinsic primary afferents because these tend to be more involved in visceral sensory processing and relay to the CNS.
