570 DIGESTION. 



closed the glottis. M. Chaussier thinks, that the sterno-hyoidei muscles 

 now act, and aid in producing the descent of the parts. 1 The author 

 had an excellent opportunity for noticing the laryngeal phenomena of 

 deglutition in a man, who had cut his throat, and in whom a fistulous 

 opening remained, which permitted the inferior ligaments of the larynx 

 to be seen distinctly. The glottis was observed to be firmly closed. 2 

 M. Longet, 3 who has made experiments connected with this subject on 

 animals, is disposed to think, that the displacements of the base of the 

 tongue and epiglottis are the two most important conditions,' and that 

 the closed glottis is only the last obstacle set up against the passage 

 of food into the larynx; but he evidently assigns too much importance 

 to the epiglottis. 



The velum pendulum, then, protects the posterior nares and the 

 orifices of the Eustachian tube from the entrance of the food ; and the 

 epiglottis, the elevation of the larynx, with the contraction of the mus- 

 cles that close the glottis, are the great agents in preventing it from 

 passing into the larynx. The whole of this second stage consists of 

 rapid movements, of an entirely involuntary character, which, accord- 

 ing to Bellingeri, 4 are under the presidency of the palatine filaments of 

 the fifth pair; but these filaments are sensory; the motor filaments 

 being probably derived from the pneumogastric ; or, according to M. 

 Longet, from the spinal. 5 



3. In the third stage, the pharynx, by its contraction, forces the ali- 

 mentary bolus into the oesophagus, so as to somewhat dilate the upper 

 part of the organ. The upper circular fibres are thus excited to action, 

 and force the food onward. In this way, by the successive contraction 

 of the circular fibres, it reaches the stomach. In the upper part of the 

 oesophagus, the relaxation of the circular fibres speedily follows their 

 contraction; but this is not the case in the lowest third, the circular 

 fibres remaining contracted, for some time after the entrance of the 

 bolus into the stomach, probably to prevent its return into the oeso- 

 phagus. The passage of the bolus along the oesophagus is by no means 

 rapid. M. Magendie 6 affirms, that he was struck, in the prosecution of 

 his experiments, with the slowness of its progression. At times, it was 

 two or three minutes before reaching the stomach ; at others, it stopped 

 repeatedly, and for some time. Occasionally, it even ascended from 

 the inferior extremity of the oesophagus towards the neck, and subse- 

 quently descended again. When any obstacle existed to its entrance 

 into the stomach, this movement was repeated a number of times, before 

 the food was rejected. Every one must have felt the slowness of the 

 progression of the food through the oesophagus when a rather larger 

 morsel than usual has been swallowed. If it stops, we are in the habit 

 of aiding its progress by drinking some fluid, or by swallowing a piece 

 of bread. Occasionally, however, the probang is necessary to propel it. 

 The pain produced in these cases, according to M. Magendie, is owing 



-1 Adelon, op. citat., ii. 424. 



2 Dunglison's American Medical Intelligencer, Oct., 1841, p. 73. 



3 L'Examinateur Medical, 17 Oct., 1841 ; and Brit, and For. Med. Rev., Jan., 1842, p. 228. 

 * Dissert. Inaugural. Turin, 1823 ; noticed in Edinb. Med. and Surg. Journ. for July, 1834. 

 5 Traite de Physiologie, ii. 337, Paris, 1850. 6 Op. citat., ii. 69. 



