Innervation of the Stomach

Considerable attention has been directed toward the study of the motility of the stomach and its regulation by the extrinsic nerves, but in spite of many investigations, our knowledge is still very incomplete. This is probably due to the complicated nature of the peripheral nervous mechanism and, further, our ignorance of the physiology of plain muscle. Critisicm may be directed against many experiments, as investigators have not paid strict attention to the use of anesthetic and preparat,ion of the animal. It is not fully realized that the stomach is an organ extremely sensitive to shock, indeed, as Hughson (70) has pointed out, even simple laparotomy will cause inhibition of movements and loss of tone, which may last unless precautions are taken, for a considerable period. The introduction by Cannon (29) of the x-ray technique for the study of the position, size and movements of the stomach made it possible to make qualitative observations and to investigate the factors regulating motility. For quantitative records, however, recourse must still be made to direct methods and the use of decerebrate a#nd decapi-tate preparations allows experiments to be made without the use of anesthetics. These preparations, while offering considerable advantages, are not ideal, as tlhe actual operation causes considerable shock to the stomach. Further, the recent work of Beattie, Brow and Long (11) suggests that decerebrations made at certain levels may injure nuclei of the hypothalamus, thus interfering with the extrinsic nerve supply. While the use of isolated vagus and sympathetic smooth muscle preparations possesses obvious disadvantages, namely, loss of blood supply, anoxemia, etc., it nevertheless affords the only means of making a quantitative study of the effect of stimulating the vagus and sympa-thetic nerves and following accurately the response of the muscles to different strengths and frequencies of stimulation. The excellent monograph of Cannon (30) published in 1911 deals with the mechanical factors of digestion, while Alvarez (2) in his recent book