On Splanchnic Motor Responses of Stomach Movements Produced by Stimulation of the Medulla Oblongata and Spinal Cord.

It has already been reported by many authors that the motor center of the stomach is located in dorsal nucleus alae cinerea(the dorsal nucleus of the vagus nerve)in the medulla oblongata5), and that the motor pathways to the stomach from medulla are contained only in the vagus nerves6,10). However, as it was previously reported by one of the present authors, regarding the augmented motor reflexes of stomach movement from urinary bladder13), distal colon15 and ileum12), and regarding the motor effects of the central stimulation of the sciatic14) and vagus nerves17), the efferent pathways of these motor reflexes were demonstrated not only in the vagus nerves but also in the splanchnic nerves. These findings are also supported by the facts that the augmented motor responses of stomach movement were obtained by the stimulation of the peripheral end of the splanchnic nerves and thoracic sympathetic trunk under certain conditions16). Therefore, if the medulla is stimulated, it may be expected to demonstrate the splanchnic motor effect of the stomach movements, through the spinal cord to the splanchnic nerves, as well as to obtain the motor effect through the vagus nerves. The stimulation of the spinal cord will also produce the augmented motor effect of the stomach. The present study was undertaken in order to obtain the motor responses of stomach by the stimulation of the medulla oblongata and the cervical and thoracic regions of the spinal cord. The stimulated positions were examined histologically.