196 EQUINE PHYSIOLOGY. 



ball, the latter not taking place if the action is made behind the 

 ganglion, by leaving the sympathetic attachments intact. Stimu- 

 lation causes exquisite pain, as it is the most sensitive nerve in 

 the body. Section of the inferior maxillary branch causes paral- 

 ysis of the muscles of mastication on the same side, and loss of 

 sensation in one lateral half of the tongue. Stimulation causes a 

 spasm of the- same muscles. 



The Sixth or Abducens is purely motor, and, if cut, we have 

 an inability to carry the eye outward. 



The Seventh or Facial is motor, and also sends the chorda 

 tympani as a special nerve of taste to the anterior two-thirds of 

 the tongue. 



Section causes paralysis of the superficial muscles of the face, 

 stapedius, occipito-styloid, digastric, stylo-hyoid, subcutaneous 

 muscle of -the neck and soft palate through the great petrosal to 

 Meckel's ganglion. There is also loss of taste on the anterior 

 two-thirds of the tongue on the same side. 



Stimulation causes contraction of the same muscles. 



The Eighth or Auditory is a nerve of special sense purely. 

 Section produces deafness on the same side. 



The Ninth or Glosso-pharyngeal is a mixed nerve, being 

 one of general sensation to the pharynx and fauces, of special 

 sense of taste to the back part of the tongue, and of motion to 

 the pharyngeal muscles in part. It is concerned obviously in 

 deglutition. 



The Tenth or Pneumogastric. 



The auricular branch gives sensation to the external ear. 



The pharyngeal gives sensation to pharynx and to muscles con- 

 cerned in deglutition. 



If the superior laryngeal branch is stimulated, spasm of the 

 glottis and diaphragm results. 



If the inferior laryngeal is cut, an arrest of the respiratory 

 movements of the glottis takes place, at it supplies all the muscles 

 of the larynx except the crico-thyroid. 



Cardiac Branches. If the nerve is cut in the neck, its inhibit- 

 ory action on the heart is taken off and it is increased in fre- 

 quency. Galvanization of the peripheral end decreases its action 

 and stops it in diastole, if strong enough. 



