MOVEMENTS OF THE ALIMENTARY CANAL DEGLUTITION. 131 



alous infant, in which the power of swallowing seems as vigorous as in 

 the perfect one. But if the "nervous" circle be destroyed, either by divi- 

 sion of the trunks, or by injury of any kind to the portion of the nervous 

 centres connected with them, the action can no longer be performed; and 

 thus we see that, when the effects of apoplexy are extending themselves 

 from the brain to the spinal cord, whilst the respiration becomes stertorous, 

 the power of Deglutition is lost, and then respiration also speedily ceases. 



89. Our knowledge of the nerves specially concerned in this action, is 

 principally due to the very careful and well-conducted experiments of Dr. J. 

 Reid, 1 which have been fully corroborated by the more recent observations 

 of MM. Vulpian' 2 and Jolyet. From a careful examination of the actions 

 of deglutition, and of the influence of various nerves upon them, Dr. Reid 

 drew the following conclusions: The excltor impressions are conveyed to the 

 Medulla Oblongata chiefly through the Glosso-pharyngeal, but also along 

 the branches of the Fifth pair distributed upon the fauces, and along the 

 superior laryngeal branches of the Pueumogastric distributed upon the 

 pharynx. The motor influence passes chiefly along the pharyngeal branches 

 of the Pneumogastric, which are probably originally derived from the 

 Spinal Accessory; along the branches of the Hypoglossal, distributed to the 

 muscles of the tongue, and to the sterno-hyoid, sterno-thyroid, and thyro- 

 hyoid muscles; along the motor filaments of the Recurrent laryugeals; 

 through some of the branches of the Fifth, supplying the elevator muscles 

 of the lower jaw ; along the branches of the Facial, ramifying upon the 

 digastric and stylo-hyoid muscles and upon those of the lower part of the 

 face; and probably along some of the branches of the Cervical plexus, which 

 unite themselves to the desceudens noni. It was further observed by Dr. 

 Reid, that the stylo-pharyugeus muscle is usually thrown into contraction, 

 when the roots of the Glosso-pharyugeal nerve are irritated; and as this 



'has been also noticed by Mayo, Volkmanu, and others, we are probably to 

 consider the Glosso-pharyngeal a motor nerve, in. so far as that muscle is 

 concerned. 3 



90. When the food has been propelled downwards by the Pharyugeal 

 muscles, so far as their action extends, its further progress through the 

 CExopJtayus is effected by a kind of peristaltic contraction of the muscular 

 coat of the tube; and Dr. J. Reid found, by repeated experiment, that the 

 continuity of the oesophageal branches of the Pueumogastric with the Me- 



1 Edin. Mecl. and Surg. Journ., vol. xlix; and Physiological, Anatomical, and 

 Pathological Researches, chap. iv. 



2 Ecvue de Cours Scientih'ques, 18'JO, t. iii, p. 754. 



3 Op. cit. , pp. 258-200. It seems not improbable that the discrepant results obtained 

 by different experimenters on this point, are partly to be explained by differences 

 in the distribution of the nerves in the several species of animals operated on. Thus 

 in the experiments of Prevost and Waller on the Rabbit (Brown-Sequard's Archives 

 de Physiologic, 1870, pp. 185 and 343), it appeared that in this animal the glosso- 

 pharyngeal nerve takes no part in the reflex phenomena of deglutition, the fifth being 

 the principal sensory nerve, and the superior laryngeal branch of the pneumogastric 

 contributing to the reflex movement by its sensory branches distributed to the mu- 

 cous membrane covering the epiglossus, the aryteno-epiglottidean folds, the superior 

 borders of the laryngeal orifice, and the cartilages of Santorini. In Chauveau's ex- 

 periments on the Home (Journal de la Physiologic, t. v, pp. 190 and 323), direct 

 irritation of the upper roots of the vagus caused contraction chiefly of the inferior 

 constrictor of the oesophagus; of the middle roots, contraction of the pharynx; and 

 of the lower roots, contraction of the upper constrictor and levator ; though all acted 

 to some extent upon the whole pharynx and oesophagus. The spinal accessory, glosso- 

 pharyngeal, facial, hypoglossal, and cervical sympathetic nerves, had little or no 

 action on the movements of the pharynx oesophagus, or stomach in this animal. 

 See also Goltz (Studien, etc., in Pfluger's Arehiy, 1872, vi, p. 616), for the move- 

 ments of the oesophagus in the Frog. 



