304 A MANUAL OF PHYSIOLOGY 



nerve.* A feather has sometimes been swallowed involuntarily 

 by a reflex movement of deglutition set up while the soft palate 

 or pharynx was being tickled to produce vomiting. Artificial 

 stimulation of the central end of the superior laryngeal will 

 cause the movements of deglutition independently of the presence 

 of food or liquid ; but if the central end of the glosso-pharyngeal 

 nerve be stimulated at the same time, the movements do not 

 occur. The glosso-pharyngeal is therefore able to inhibit the 

 deglutition centre, and it is owing to the action of this nerve 

 that in a series of efforts at swallowing, repeated within less than 

 a certain short interval (about a second), only the last is success- 

 ful. It is also through the glosso-pharyngeal nerve that the 

 respiratory movements are inhibited during deglutition. When 

 the central end of this nerve is stimulated, respiration is stopped 

 for four or five seconds, and this cessation is distinguished from 

 that produced by any other afferent nerve by the circumstance 

 that it occurs not in expiration exclusively or in inspiration 

 exclusively, but with the respiratory muscles in the precise degree 

 of contraction in which they happened to be at the moment of 

 stimulation. The efferent nerves of the reflex act of deglutition 

 are the hypoglossal to the tongue and the thyro-hyoid and other 

 muscles concerned in raising the larynx ; the glosso-pharyngeal, 

 vagus, facial and fifth to the muscles of the palate, fauces, and 

 pharynx ; the fifth to the mylo-hyoid ; and the vagus to the 

 larynx and oesophagus. Section of the vagus interferes with 

 the passage of food along the oesophagus ; stimulation of its 

 peripheral end causes cesophageal movements. 



Movements of the Stomach and Intestines. The whole of 

 the stomach does not take part equally in the movements associ- 

 ated with digestion. We may divide the organ, both anatomically 

 and functionally, into two portions a pyloric portion, or antrum 

 pylori, comprising about a fifth of the stomach, and a larger 

 cardiac portion, or fundus.^ At the junction of the antrum 

 and the fundus the circular muscular coat is slightly thickened 

 into a ring called the ' transverse band,' or ' sphincter of the 

 antrum.' In the living stomach the region of the transverse 



* It appears that the most influential reflex paths may differ in different 

 animals. In the rabbit, e.g., the reflex is set up by excitation of the 

 trigeminal fibres which supply the mucous membrane anterior to the 

 tonsils, in the dog and cat by excitation of the glosso-pharyngeal fibres 

 in the posterior wall of the pharynx, and in monkeys by excitation of 

 the trigeminal branches distributed to the mucous membrane over the 

 tonsils (Kahn). 



f Here ' fundus ' is used in the sense in which it is generally employed 

 in speaking of the stomach of the dog or cat as signifying the whole of the 

 organ with the exception of the antrum pylori. By the fundus of the 

 human stomach most writers mean only the cul-de-sac at the cardiac end ; 

 the portion intervening between it and the antrum pylori is often termed 

 the body of the stomach. 



