THE PNEUMOGASTRIC NERVE. 559 



which it derives from the reception of filaments from the 

 sympathetic, accessory, and cervical nerves, and, probably, 

 the glosso-pharyngeal and facial. 



The most probable account of the particular functions 

 which the branches of the pneumogastric nerve discharge 

 in the several parts to which they are distributed, may be 

 drawn from Dr. John Reid's experiments on dogs. They 

 show that, I. The pharyngeal branch is the principal, if 

 not the sole motor nerve of the pharynx and soft palate, 

 and is most probably wholly motor ; a part of its motor 

 fibres being derived from the internal branch of the acces- 

 sory nerve. 2. The inferior 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 gives rise to no action in any 

 of the muscles attached to the arytenoid cartilages, but 

 merely to contractions of the crico- thyroid muscle. 3. The 

 superior laryngeal nerve is chiefly sensitive ; the inferior, 

 for the most part, motor; for division of the recurrent 

 nerves puts an end to the motions of the glottis, but 

 without lessening the sensibility of the mucous membrane ; 

 and division of the superior laryngeal nerves leaves the 

 movements of the glottis unaffected, but deprives it of its 

 sensibility. 4. The motions of the oesophagus are depen- 

 dent on motor fibres of the pneumogastric, and are pro- 

 bably excited by impressions made upon sensitive fibres of 

 the same ; for irritation of its trunk excites motions of the 

 cesophagus, which extend over the cardiac portions of the 

 stomach ; and division of the trunk paralyzes the oeso- 

 phagus, which : then becomes distended with the food. 

 5. The cardiac branches of the pneumogastric nerve are 

 one, but not the sole channel through which the influence 

 of the central organs and of mental emotions is transmitted 

 to the heart. 6. The pulmonary branches form the prin- 

 cipal, but not the sole channel by which the impressions 

 on the mucous surface of the lungs that excite respiration, 



