Bauhaus-Universität Weimar

522 
PROPERTIES OF THE VAGUS NERVE. 
Dr. Reid found that when the external branch of the spinal acces¬ 
sory was strongly compressed between the blades of the forceps, or 
firmly included in a ligature, the animal gave very decided evidence 
of suffering pain; but he does not pretend to determine whether the 
sensitive filaments on which this result depends belong originally to 
the nerve, or whether it derives them from other nerves at the base of 
the cranium. 
The vagus affords sensitive influence to all the parts to which it 
is distributed; namely, to the organs of voice and respiration, the 
pharynx, oesophagus, and stomach; moreover, it gives a sensitive 
branch, which penetrates the petrous portion of the temporal bone, 
to the external ear,—the ramus auricularis; and the facial nerve 
probably derives its sensitive endowment from its connection with 
this branch of the vagus within the temporal bone. 
The branches of the vagus, which are motor as well as sensitive, 
are the pharyngeal and laryngeal. Division of the inferior laryngeal 
nerve, or of the vagus in the neck on both sides, paralyses incom¬ 
pletely the small muscles of the larynx; the voice is lost, but is re¬ 
gained in a few days, from the superior laryngeal nerve continuing 
to exert its influence. The assertion of Magendie, that the superior 
laryngeal nerve is distributed solely to the contractors of the glottis, 
and the inferior to the dilators, was not confirmed by Schlemm’s 
dissections. The vagus has no motor influence on the stomach; 
neither by galvanism, nor by mechanical irritation applied to the 
nerve in the neck, can motions of the stomach be excited: this results 
from the experiments of Magendie, Mayo, and myself. 
With respect to the motor and sensitive properties of the individual 
branches of the vagus, we learn from the experiments of Dr. Reid: 
1. That the pharyngeal branch in the dog is the principal, if not the 
sole motor nerve of the pharynx and soft palate, and that it is most 
probably wholly motor; a part of its motor fibres being derived from 
the internal branch of the spinal accessory nerve. 2. That the in¬ 
ferior laryngeal nerve is the motor nerve of the larynx, irritation of 
it producing vigorous movements of the arytenoid cartilages; while 
irritation of the superior laryngeal nerve (by galvanism) gave rise to 
no action in any of the muscles attached to the arytenoid cartilages, 
but merely to contractions of the crico-thyroid muscle. Experiments 
on living dogs showed also that division of the recurrent nerves put 
an end to the motions of the glottis, but that the sensibility of the 
mucous membrane remained; that division of the superior laryngeal 
nerves left the movements of the glottis unaffected, but deprived it 
of its sensibility. These results agree with the anatomy of the 
nerves. The superior laryngeal nerve, therefore, is chiefly sensitive; 
the inferior, for the most part, motor. 3. (Esophageal branches. 
Dr. Reid found, as had been done by previous observers, that irrita¬ 
tion of the trunk of the vagus excited motions of the oesophagus, 
which extended over the cardiac portion of the stomach; and that 
division of the vagus paralysed the movements of the oesophagus, 
which became distended with the food which was afterwards taken. 
The motions of the oesophagus, therefore, are dependent on motor
        

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