96 HUMAN PHYSIOLOGY. 



maxillary ganglion, the parotid and sub-lingual glands, external auditory 

 meatus, mucous membrane of the month, anterior two-thirds of the tongue 

 (lingual branch), gums, arches of the palate, teeth of the lower jaw, 

 and integument of the lower part of the face, and t the muscles of 

 mastication. 



The small root passes forward beneath the ganglion of Gasser, through 

 the foramen ovale, and joins the inferior maxillary division of the large 

 root, which then divides into an anterior and posterior branch, the former 

 of which is distributed to the musdes of mastication, viz. : temporal, mas- 

 seter, internal and external pterygoid muscles. 



Properties. It is the most acutely sensitive nerve in the body, and 

 endows all the parts to which it is distributed with general sensibility. 



Irritation of the large root, or any of its branches, will give rise to 

 marked evidence of pain ; the various forms of neuralgia of the head and 

 face being occasioned by compression, disease, or exposure of some of its 

 terminal branches. 



Division of the large root within the cranium is followed at once by a 

 complete abolition of all sensibility in the head and face, but is not attended 

 by any loss of Hiotioa. The integument, mucous membranes and the eye 

 may be lacerated, cut or bruise d r without the animal exhibiting any evidence 

 of pain. At the same time the lachrymal secretion is diminished, the pupil 

 becomes contracted, the eyeball is protruded, and the sensibility of the 

 tongue is abolished. 



The reflex movements of deglutition are also somewhat impaired ; the 

 impression of the food being unable to reach and excite the nerve centre in 

 the medulla oblongata. 



Galvanization of the small root produces movements of the muscles of 

 mastication ; section of the root causes paralysis of these muscles, and the 

 jaw is drawn to the opposite side, by the action of the opposing muscles. 



Influence upon the Special Senses. After division of the large root 

 within the cranium, a disturbance in the nutrition of the special senses 

 sooner or later manifests itself. 



Sight. In the course of twenty-four hours the eye becomes very vascular 

 and inflamed, the cornea becomes opaque and ulcerates, the humors are dis- 

 charged, and the eye is totally destroyed. 



Smell. The nasal mucous membrane swells up, becomes fungous, and is 

 liable to bleed on the slightest irritation. The mucus is increased in 

 amount, so as to obstruct the nasal passages; the sense of smell is finally 

 abolished. 



