THE NERVOUS SYSTEM. 433 



which sensation is most important. All the organic or nutri- 

 tive functions proceed : nails grow, wounds heal, vesicatories 



that respiration will not take place without the portion of the chorda oblon- 

 gata connected with the pneumono-gastric. The pneumono-gastric are also 

 nerves of motion to the larynx and trachea ; and are distributed to the liver, 

 spleen, kidneys, and duodenum, probably to convey impressions to them from 

 the brain under emotion, and to give them sensibility enough for sensation under 

 causes of great irritation. 



The pneumono-gastric on each side gives off, 1 . The superior laryngeal, which 

 runs to the membrane of the glottis (see Mr. Swan, On the Nerves, plate xvi., 

 Expl. of Plates, p. xlviii.), and therefore gives it sensibility, and to the arytenoid 

 museles which close it, as well as the crico-thyroid muscle which raises the 

 cricoid cartilage. (Dr. Magendie, M.6m. sur V Usage de VEpiglotte dans la Deglu- 

 tition, #c.) 



2. Twigs to numerous parts in the neck, to the facial, lingual, and three upper 

 cervical nerves, to the cardiac plexuses, the pulmonary plexuses, and the sym- 

 pathetic nerve. 



3. The inferior laryngeal or recurrent nerves (see Mr. Swan, 1. c.), which 

 supply " the membrane of the trachea as high as the membrane covering the 

 posterior part of the cricoid cartilage," and the transverse fibres at the back of 

 the trachea, " and ultimately divide into branches which terminate in the lateral 

 crico-arytenoid and thyro-arytenoid muscles," (see papers by Dr. H. Ley, Lond. 

 Med. Gazette, June 20. 1835,) besides giving branches of communication with 

 many other nerves. On account of their supplying the membrane of the glottis^ 

 Dr. Brachet found that, after removing a portion of the pneumono-gastric nerves 

 from which they spring, a ball of orris-root or a few drops of muriatic or acetic 

 acid might be admitted into the trachea of a dog without uneasiness ; whereas, 

 while the nerves were entire, a drop of blood in the trachea induced cough, and 

 the balls and acids most violent cough, which instantly ceased on the division of 

 the nerve, and was succeeded by mucous rattle without expectoration, the mucus 

 no longer exciting sensation, nor the muscles possessing power for its expulsion > 

 and death ensued in less than an hour. (Reck. Exper. p 167.) As the recurrents 

 supply the opening muscles of the glottis, the division of those nerves causes the 

 death of young animals, since in them the rima glottidis is narrow ; in the older, 

 or in animals whose rima glottidis is of such a form that its sides cannot touch, 

 dyspnoea and a croaking sound of the voice instantly follow from their approxi- 

 mation.* 



* Dr. Le Gallois, Experiences sur le Principe de la Vie. 



Some think that filaments go from the recurrents to the closing muscles also ; 

 but Dr. H. Ley conjectures, with probability, "that these, together with the ana- 

 stomosing branches of the superior laryngeal and the recurrent, are intended for 

 those rapid and delicate associated actions connected with the voice by which 

 the chordae vocales are rendered more or less tense, and their vibrating portions 

 longer or shorter j whilst the main branches, described by Mr. Swan as termi- 



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